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Diffstat (limited to 'lib/libpcap/libpcap/pcap-linux.c')
| -rw-r--r-- | lib/libpcap/libpcap/pcap-linux.c | 7534 |
1 files changed, 7534 insertions, 0 deletions
diff --git a/lib/libpcap/libpcap/pcap-linux.c b/lib/libpcap/libpcap/pcap-linux.c new file mode 100644 index 0000000..70334b3 --- /dev/null +++ b/lib/libpcap/libpcap/pcap-linux.c @@ -0,0 +1,7534 @@ +/* + * pcap-linux.c: Packet capture interface to the Linux kernel + * + * Copyright (c) 2000 Torsten Landschoff <torsten@debian.org> + * Sebastian Krahmer <krahmer@cs.uni-potsdam.de> + * + * License: BSD + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. The names of the authors may not be used to endorse or promote + * products derived from this software without specific prior + * written permission. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. + * + * Modifications: Added PACKET_MMAP support + * Paolo Abeni <paolo.abeni@email.it> + * Added TPACKET_V3 support + * Gabor Tatarka <gabor.tatarka@ericsson.com> + * + * based on previous works of: + * Simon Patarin <patarin@cs.unibo.it> + * Phil Wood <cpw@lanl.gov> + * + * Monitor-mode support for mac80211 includes code taken from the iw + * command; the copyright notice for that code is + * + * Copyright (c) 2007, 2008 Johannes Berg + * Copyright (c) 2007 Andy Lutomirski + * Copyright (c) 2007 Mike Kershaw + * Copyright (c) 2008 Gábor Stefanik + * + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +/* + * Known problems with 2.0[.x] kernels: + * + * - The loopback device gives every packet twice; on 2.2[.x] kernels, + * if we use PF_PACKET, we can filter out the transmitted version + * of the packet by using data in the "sockaddr_ll" returned by + * "recvfrom()", but, on 2.0[.x] kernels, we have to use + * PF_INET/SOCK_PACKET, which means "recvfrom()" supplies a + * "sockaddr_pkt" which doesn't give us enough information to let + * us do that. + * + * - We have to set the interface's IFF_PROMISC flag ourselves, if + * we're to run in promiscuous mode, which means we have to turn + * it off ourselves when we're done; the kernel doesn't keep track + * of how many sockets are listening promiscuously, which means + * it won't get turned off automatically when no sockets are + * listening promiscuously. We catch "pcap_close()" and, for + * interfaces we put into promiscuous mode, take them out of + * promiscuous mode - which isn't necessarily the right thing to + * do, if another socket also requested promiscuous mode between + * the time when we opened the socket and the time when we close + * the socket. + * + * - MSG_TRUNC isn't supported, so you can't specify that "recvfrom()" + * return the amount of data that you could have read, rather than + * the amount that was returned, so we can't just allocate a buffer + * whose size is the snapshot length and pass the snapshot length + * as the byte count, and also pass MSG_TRUNC, so that the return + * value tells us how long the packet was on the wire. + * + * This means that, if we want to get the actual size of the packet, + * so we can return it in the "len" field of the packet header, + * we have to read the entire packet, not just the part that fits + * within the snapshot length, and thus waste CPU time copying data + * from the kernel that our caller won't see. + * + * We have to get the actual size, and supply it in "len", because + * otherwise, the IP dissector in tcpdump, for example, will complain + * about "truncated-ip", as the packet will appear to have been + * shorter, on the wire, than the IP header said it should have been. + */ + + +#define _GNU_SOURCE + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif + +#include <errno.h> +#include <stdio.h> +#include <stdlib.h> +#include <ctype.h> +#include <unistd.h> +#include <fcntl.h> +#include <string.h> +#include <limits.h> +#include <sys/stat.h> +#include <sys/socket.h> +#include <sys/ioctl.h> +#include <sys/utsname.h> +#include <sys/mman.h> +#include <linux/if.h> +#include <linux/if_packet.h> +#include <linux/sockios.h> +#include <netinet/in.h> +#include <linux/if_ether.h> +#include <net/if_arp.h> +#include <poll.h> +#include <dirent.h> + +#include "pcap-int.h" +#include "pcap/sll.h" +#include "pcap/vlan.h" + +/* + * If PF_PACKET is defined, we can use {SOCK_RAW,SOCK_DGRAM}/PF_PACKET + * sockets rather than SOCK_PACKET sockets. + * + * To use them, we include <linux/if_packet.h> rather than + * <netpacket/packet.h>; we do so because + * + * some Linux distributions (e.g., Slackware 4.0) have 2.2 or + * later kernels and libc5, and don't provide a <netpacket/packet.h> + * file; + * + * not all versions of glibc2 have a <netpacket/packet.h> file + * that defines stuff needed for some of the 2.4-or-later-kernel + * features, so if the system has a 2.4 or later kernel, we + * still can't use those features. + * + * We're already including a number of other <linux/XXX.h> headers, and + * this code is Linux-specific (no other OS has PF_PACKET sockets as + * a raw packet capture mechanism), so it's not as if you gain any + * useful portability by using <netpacket/packet.h> + * + * XXX - should we just include <linux/if_packet.h> even if PF_PACKET + * isn't defined? It only defines one data structure in 2.0.x, so + * it shouldn't cause any problems. + */ +#ifdef PF_PACKET +# include <linux/if_packet.h> + + /* + * On at least some Linux distributions (for example, Red Hat 5.2), + * there's no <netpacket/packet.h> file, but PF_PACKET is defined if + * you include <sys/socket.h>, but <linux/if_packet.h> doesn't define + * any of the PF_PACKET stuff such as "struct sockaddr_ll" or any of + * the PACKET_xxx stuff. + * + * So we check whether PACKET_HOST is defined, and assume that we have + * PF_PACKET sockets only if it is defined. + */ +# ifdef PACKET_HOST +# define HAVE_PF_PACKET_SOCKETS +# ifdef PACKET_AUXDATA +# define HAVE_PACKET_AUXDATA +# endif /* PACKET_AUXDATA */ +# endif /* PACKET_HOST */ + + + /* check for memory mapped access avaibility. We assume every needed + * struct is defined if the macro TPACKET_HDRLEN is defined, because it + * uses many ring related structs and macros */ +# ifdef PCAP_SUPPORT_PACKET_RING +# ifdef TPACKET_HDRLEN +# define HAVE_PACKET_RING +# ifdef TPACKET3_HDRLEN +# define HAVE_TPACKET3 +# endif /* TPACKET3_HDRLEN */ +# ifdef TPACKET2_HDRLEN +# define HAVE_TPACKET2 +# else /* TPACKET2_HDRLEN */ +# define TPACKET_V1 0 /* Old kernel with only V1, so no TPACKET_Vn defined */ +# endif /* TPACKET2_HDRLEN */ +# endif /* TPACKET_HDRLEN */ +# endif /* PCAP_SUPPORT_PACKET_RING */ +#endif /* PF_PACKET */ + +#ifdef SO_ATTACH_FILTER +#include <linux/types.h> +#include <linux/filter.h> +#endif + +#ifdef HAVE_LINUX_NET_TSTAMP_H +#include <linux/net_tstamp.h> +#endif + +#ifdef HAVE_LINUX_SOCKIOS_H +#include <linux/sockios.h> +#endif + +#ifdef HAVE_LINUX_IF_BONDING_H +#include <linux/if_bonding.h> + +/* + * The ioctl code to use to check whether a device is a bonding device. + */ +#if defined(SIOCBONDINFOQUERY) + #define BOND_INFO_QUERY_IOCTL SIOCBONDINFOQUERY +#elif defined(BOND_INFO_QUERY_OLD) + #define BOND_INFO_QUERY_IOCTL BOND_INFO_QUERY_OLD +#endif +#endif /* HAVE_LINUX_IF_BONDING_H */ + +/* + * Got Wireless Extensions? + */ +#ifdef HAVE_LINUX_WIRELESS_H +#include <linux/wireless.h> +#endif /* HAVE_LINUX_WIRELESS_H */ + +/* + * Got libnl? + */ +#ifdef HAVE_LIBNL +#include <linux/nl80211.h> + +#include <netlink/genl/genl.h> +#include <netlink/genl/family.h> +#include <netlink/genl/ctrl.h> +#include <netlink/msg.h> +#include <netlink/attr.h> +#endif /* HAVE_LIBNL */ + +/* + * Got ethtool support? + */ +#ifdef HAVE_LINUX_ETHTOOL_H +#include <linux/ethtool.h> +#endif + +#ifndef HAVE_SOCKLEN_T +typedef int socklen_t; +#endif + +#ifndef MSG_TRUNC +/* + * This is being compiled on a system that lacks MSG_TRUNC; define it + * with the value it has in the 2.2 and later kernels, so that, on + * those kernels, when we pass it in the flags argument to "recvfrom()" + * we're passing the right value and thus get the MSG_TRUNC behavior + * we want. (We don't get that behavior on 2.0[.x] kernels, because + * they didn't support MSG_TRUNC.) + */ +#define MSG_TRUNC 0x20 +#endif + +#ifndef SOL_PACKET +/* + * This is being compiled on a system that lacks SOL_PACKET; define it + * with the value it has in the 2.2 and later kernels, so that we can + * set promiscuous mode in the good modern way rather than the old + * 2.0-kernel crappy way. + */ +#define SOL_PACKET 263 +#endif + +#define MAX_LINKHEADER_SIZE 256 + +/* + * When capturing on all interfaces we use this as the buffer size. + * Should be bigger then all MTUs that occur in real life. + * 64kB should be enough for now. + */ +#define BIGGER_THAN_ALL_MTUS (64*1024) + +/* + * Private data for capturing on Linux SOCK_PACKET or PF_PACKET sockets. + */ +struct pcap_linux { + u_int packets_read; /* count of packets read with recvfrom() */ + long proc_dropped; /* packets reported dropped by /proc/net/dev */ + struct pcap_stat stat; + + char *device; /* device name */ + int filter_in_userland; /* must filter in userland */ + int blocks_to_filter_in_userland; + int must_do_on_close; /* stuff we must do when we close */ + int timeout; /* timeout for buffering */ + int sock_packet; /* using Linux 2.0 compatible interface */ + int cooked; /* using SOCK_DGRAM rather than SOCK_RAW */ + int ifindex; /* interface index of device we're bound to */ + int lo_ifindex; /* interface index of the loopback device */ + bpf_u_int32 oldmode; /* mode to restore when turning monitor mode off */ + char *mondevice; /* mac80211 monitor device we created */ + u_char *mmapbuf; /* memory-mapped region pointer */ + size_t mmapbuflen; /* size of region */ + int vlan_offset; /* offset at which to insert vlan tags; if -1, don't insert */ + u_int tp_version; /* version of tpacket_hdr for mmaped ring */ + u_int tp_hdrlen; /* hdrlen of tpacket_hdr for mmaped ring */ + u_char *oneshot_buffer; /* buffer for copy of packet */ + int poll_timeout; /* timeout to use in poll() */ +#ifdef HAVE_TPACKET3 + unsigned char *current_packet; /* Current packet within the TPACKET_V3 block. Move to next block if NULL. */ + int packets_left; /* Unhandled packets left within the block from previous call to pcap_read_linux_mmap_v3 in case of TPACKET_V3. */ +#endif +}; + +/* + * Stuff to do when we close. + */ +#define MUST_CLEAR_PROMISC 0x00000001 /* clear promiscuous mode */ +#define MUST_CLEAR_RFMON 0x00000002 /* clear rfmon (monitor) mode */ +#define MUST_DELETE_MONIF 0x00000004 /* delete monitor-mode interface */ + +/* + * Prototypes for internal functions and methods. + */ +static int get_if_flags(const char *, bpf_u_int32 *, char *); +static int is_wifi(int, const char *); +static void map_arphrd_to_dlt(pcap_t *, int, int, const char *, int); +static int pcap_activate_linux(pcap_t *); +static int activate_old(pcap_t *); +static int activate_new(pcap_t *); +static int activate_mmap(pcap_t *, int *); +static int pcap_can_set_rfmon_linux(pcap_t *); +static int pcap_read_linux(pcap_t *, int, pcap_handler, u_char *); +static int pcap_read_packet(pcap_t *, pcap_handler, u_char *); +static int pcap_inject_linux(pcap_t *, const void *, size_t); +static int pcap_stats_linux(pcap_t *, struct pcap_stat *); +static int pcap_setfilter_linux(pcap_t *, struct bpf_program *); +static int pcap_setdirection_linux(pcap_t *, pcap_direction_t); +static int pcap_set_datalink_linux(pcap_t *, int); +static void pcap_cleanup_linux(pcap_t *); + +/* + * This is what the header structure looks like in a 64-bit kernel; + * we use this, rather than struct tpacket_hdr, if we're using + * TPACKET_V1 in 32-bit code running on a 64-bit kernel. + */ +struct tpacket_hdr_64 { + uint64_t tp_status; + unsigned int tp_len; + unsigned int tp_snaplen; + unsigned short tp_mac; + unsigned short tp_net; + unsigned int tp_sec; + unsigned int tp_usec; +}; + +/* + * We use this internally as the tpacket version for TPACKET_V1 in + * 32-bit code on a 64-bit kernel. + */ +#define TPACKET_V1_64 99 + +union thdr { + struct tpacket_hdr *h1; + struct tpacket_hdr_64 *h1_64; +#ifdef HAVE_TPACKET2 + struct tpacket2_hdr *h2; +#endif +#ifdef HAVE_TPACKET3 + struct tpacket_block_desc *h3; +#endif + void *raw; +}; + +#ifdef HAVE_PACKET_RING +#define RING_GET_FRAME_AT(h, offset) (((union thdr **)h->buffer)[(offset)]) +#define RING_GET_CURRENT_FRAME(h) RING_GET_FRAME_AT(h, h->offset) + +static void destroy_ring(pcap_t *handle); +static int create_ring(pcap_t *handle, int *status); +static int prepare_tpacket_socket(pcap_t *handle); +static void pcap_cleanup_linux_mmap(pcap_t *); +static int pcap_read_linux_mmap_v1(pcap_t *, int, pcap_handler , u_char *); +static int pcap_read_linux_mmap_v1_64(pcap_t *, int, pcap_handler , u_char *); +#ifdef HAVE_TPACKET2 +static int pcap_read_linux_mmap_v2(pcap_t *, int, pcap_handler , u_char *); +#endif +#ifdef HAVE_TPACKET3 +static int pcap_read_linux_mmap_v3(pcap_t *, int, pcap_handler , u_char *); +#endif +static int pcap_setfilter_linux_mmap(pcap_t *, struct bpf_program *); +static int pcap_setnonblock_mmap(pcap_t *p, int nonblock); +static int pcap_getnonblock_mmap(pcap_t *p); +static void pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h, + const u_char *bytes); +#endif + +/* + * In pre-3.0 kernels, the tp_vlan_tci field is set to whatever the + * vlan_tci field in the skbuff is. 0 can either mean "not on a VLAN" + * or "on VLAN 0". There is no flag set in the tp_status field to + * distinguish between them. + * + * In 3.0 and later kernels, if there's a VLAN tag present, the tp_vlan_tci + * field is set to the VLAN tag, and the TP_STATUS_VLAN_VALID flag is set + * in the tp_status field, otherwise the tp_vlan_tci field is set to 0 and + * the TP_STATUS_VLAN_VALID flag isn't set in the tp_status field. + * + * With a pre-3.0 kernel, we cannot distinguish between packets with no + * VLAN tag and packets on VLAN 0, so we will mishandle some packets, and + * there's nothing we can do about that. + * + * So, on those systems, which never set the TP_STATUS_VLAN_VALID flag, we + * continue the behavior of earlier libpcaps, wherein we treated packets + * with a VLAN tag of 0 as being packets without a VLAN tag rather than packets + * on VLAN 0. We do this by treating packets with a tp_vlan_tci of 0 and + * with the TP_STATUS_VLAN_VALID flag not set in tp_status as not having + * VLAN tags. This does the right thing on 3.0 and later kernels, and + * continues the old unfixably-imperfect behavior on pre-3.0 kernels. + * + * If TP_STATUS_VLAN_VALID isn't defined, we test it as the 0x10 bit; it + * has that value in 3.0 and later kernels. + */ +#ifdef TP_STATUS_VLAN_VALID + #define VLAN_VALID(hdr, hv) ((hv)->tp_vlan_tci != 0 || ((hdr)->tp_status & TP_STATUS_VLAN_VALID)) +#else + /* + * This is being compiled on a system that lacks TP_STATUS_VLAN_VALID, + * so we testwith the value it has in the 3.0 and later kernels, so + * we can test it if we're running on a system that has it. (If we're + * running on a system that doesn't have it, it won't be set in the + * tp_status field, so the tests of it will always fail; that means + * we behave the way we did before we introduced this macro.) + */ + #define VLAN_VALID(hdr, hv) ((hv)->tp_vlan_tci != 0 || ((hdr)->tp_status & 0x10)) +#endif + +#ifdef TP_STATUS_VLAN_TPID_VALID +# define VLAN_TPID(hdr, hv) (((hv)->tp_vlan_tpid || ((hdr)->tp_status & TP_STATUS_VLAN_TPID_VALID)) ? (hv)->tp_vlan_tpid : ETH_P_8021Q) +#else +# define VLAN_TPID(hdr, hv) ETH_P_8021Q +#endif + +/* + * Wrap some ioctl calls + */ +#ifdef HAVE_PF_PACKET_SOCKETS +static int iface_get_id(int fd, const char *device, char *ebuf); +#endif /* HAVE_PF_PACKET_SOCKETS */ +static int iface_get_mtu(int fd, const char *device, char *ebuf); +static int iface_get_arptype(int fd, const char *device, char *ebuf); +#ifdef HAVE_PF_PACKET_SOCKETS +static int iface_bind(int fd, int ifindex, char *ebuf, int protocol); +#ifdef IW_MODE_MONITOR +static int has_wext(int sock_fd, const char *device, char *ebuf); +#endif /* IW_MODE_MONITOR */ +static int enter_rfmon_mode(pcap_t *handle, int sock_fd, + const char *device); +#endif /* HAVE_PF_PACKET_SOCKETS */ +#if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) +static int iface_ethtool_get_ts_info(const char *device, pcap_t *handle, + char *ebuf); +#endif +#ifdef HAVE_PACKET_RING +static int iface_get_offload(pcap_t *handle); +#endif +static int iface_bind_old(int fd, const char *device, char *ebuf); + +#ifdef SO_ATTACH_FILTER +static int fix_program(pcap_t *handle, struct sock_fprog *fcode, + int is_mapped); +static int fix_offset(pcap_t *handle, struct bpf_insn *p); +static int set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode); +static int reset_kernel_filter(pcap_t *handle); + +static struct sock_filter total_insn + = BPF_STMT(BPF_RET | BPF_K, 0); +static struct sock_fprog total_fcode + = { 1, &total_insn }; +#endif /* SO_ATTACH_FILTER */ + +pcap_t * +pcap_create_interface(const char *device, char *ebuf) +{ + pcap_t *handle; + + handle = pcap_create_common(ebuf, sizeof (struct pcap_linux)); + if (handle == NULL) + return NULL; + + handle->activate_op = pcap_activate_linux; + handle->can_set_rfmon_op = pcap_can_set_rfmon_linux; + +#if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) + /* + * See what time stamp types we support. + */ + if (iface_ethtool_get_ts_info(device, handle, ebuf) == -1) { + pcap_close(handle); + return NULL; + } +#endif + +#if defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS) + /* + * We claim that we support microsecond and nanosecond time + * stamps. + * + * XXX - with adapter-supplied time stamps, can we choose + * microsecond or nanosecond time stamps on arbitrary + * adapters? + */ + handle->tstamp_precision_count = 2; + handle->tstamp_precision_list = malloc(2 * sizeof(u_int)); + if (handle->tstamp_precision_list == NULL) { + pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, + errno, "malloc"); + pcap_close(handle); + return NULL; + } + handle->tstamp_precision_list[0] = PCAP_TSTAMP_PRECISION_MICRO; + handle->tstamp_precision_list[1] = PCAP_TSTAMP_PRECISION_NANO; +#endif /* defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS) */ + + return handle; +} + +#ifdef HAVE_LIBNL +/* + * If interface {if} is a mac80211 driver, the file + * /sys/class/net/{if}/phy80211 is a symlink to + * /sys/class/ieee80211/{phydev}, for some {phydev}. + * + * On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at + * least, has a "wmaster0" device and a "wlan0" device; the + * latter is the one with the IP address. Both show up in + * "tcpdump -D" output. Capturing on the wmaster0 device + * captures with 802.11 headers. + * + * airmon-ng searches through /sys/class/net for devices named + * monN, starting with mon0; as soon as one *doesn't* exist, + * it chooses that as the monitor device name. If the "iw" + * command exists, it does "iw dev {if} interface add {monif} + * type monitor", where {monif} is the monitor device. It + * then (sigh) sleeps .1 second, and then configures the + * device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface + * is a file, it writes {mondev}, without a newline, to that file, + * and again (sigh) sleeps .1 second, and then iwconfig's that + * device into monitor mode and configures it up. Otherwise, + * you can't do monitor mode. + * + * All these devices are "glued" together by having the + * /sys/class/net/{device}/phy80211 links pointing to the same + * place, so, given a wmaster, wlan, or mon device, you can + * find the other devices by looking for devices with + * the same phy80211 link. + * + * To turn monitor mode off, delete the monitor interface, + * either with "iw dev {monif} interface del" or by sending + * {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface + * + * Note: if you try to create a monitor device named "monN", and + * there's already a "monN" device, it fails, as least with + * the netlink interface (which is what iw uses), with a return + * value of -ENFILE. (Return values are negative errnos.) We + * could probably use that to find an unused device. + * + * Yes, you can have multiple monitor devices for a given + * physical device. + */ + +/* + * Is this a mac80211 device? If so, fill in the physical device path and + * return 1; if not, return 0. On an error, fill in handle->errbuf and + * return PCAP_ERROR. + */ +static int +get_mac80211_phydev(pcap_t *handle, const char *device, char *phydev_path, + size_t phydev_max_pathlen) +{ + char *pathstr; + ssize_t bytes_read; + + /* + * Generate the path string for the symlink to the physical device. + */ + if (asprintf(&pathstr, "/sys/class/net/%s/phy80211", device) == -1) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: Can't generate path name string for /sys/class/net device", + device); + return PCAP_ERROR; + } + bytes_read = readlink(pathstr, phydev_path, phydev_max_pathlen); + if (bytes_read == -1) { + if (errno == ENOENT || errno == EINVAL) { + /* + * Doesn't exist, or not a symlink; assume that + * means it's not a mac80211 device. + */ + free(pathstr); + return 0; + } + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "%s: Can't readlink %s", device, pathstr); + free(pathstr); + return PCAP_ERROR; + } + free(pathstr); + phydev_path[bytes_read] = '\0'; + return 1; +} + +#ifdef HAVE_LIBNL_SOCKETS +#define get_nl_errmsg nl_geterror +#else +/* libnl 2.x compatibility code */ + +#define nl_sock nl_handle + +static inline struct nl_handle * +nl_socket_alloc(void) +{ + return nl_handle_alloc(); +} + +static inline void +nl_socket_free(struct nl_handle *h) +{ + nl_handle_destroy(h); +} + +#define get_nl_errmsg strerror + +static inline int +__genl_ctrl_alloc_cache(struct nl_handle *h, struct nl_cache **cache) +{ + struct nl_cache *tmp = genl_ctrl_alloc_cache(h); + if (!tmp) + return -ENOMEM; + *cache = tmp; + return 0; +} +#define genl_ctrl_alloc_cache __genl_ctrl_alloc_cache +#endif /* !HAVE_LIBNL_SOCKETS */ + +struct nl80211_state { + struct nl_sock *nl_sock; + struct nl_cache *nl_cache; + struct genl_family *nl80211; +}; + +static int +nl80211_init(pcap_t *handle, struct nl80211_state *state, const char *device) +{ + int err; + + state->nl_sock = nl_socket_alloc(); + if (!state->nl_sock) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: failed to allocate netlink handle", device); + return PCAP_ERROR; + } + + if (genl_connect(state->nl_sock)) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: failed to connect to generic netlink", device); + goto out_handle_destroy; + } + + err = genl_ctrl_alloc_cache(state->nl_sock, &state->nl_cache); + if (err < 0) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: failed to allocate generic netlink cache: %s", + device, get_nl_errmsg(-err)); + goto out_handle_destroy; + } + + state->nl80211 = genl_ctrl_search_by_name(state->nl_cache, "nl80211"); + if (!state->nl80211) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl80211 not found", device); + goto out_cache_free; + } + + return 0; + +out_cache_free: + nl_cache_free(state->nl_cache); +out_handle_destroy: + nl_socket_free(state->nl_sock); + return PCAP_ERROR; +} + +static void +nl80211_cleanup(struct nl80211_state *state) +{ + genl_family_put(state->nl80211); + nl_cache_free(state->nl_cache); + nl_socket_free(state->nl_sock); +} + +static int +del_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state, + const char *device, const char *mondevice); + +static int +add_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state, + const char *device, const char *mondevice) +{ + struct pcap_linux *handlep = handle->priv; + int ifindex; + struct nl_msg *msg; + int err; + + ifindex = iface_get_id(sock_fd, device, handle->errbuf); + if (ifindex == -1) + return PCAP_ERROR; + + msg = nlmsg_alloc(); + if (!msg) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: failed to allocate netlink msg", device); + return PCAP_ERROR; + } + + genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0, + 0, NL80211_CMD_NEW_INTERFACE, 0); + NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex); + NLA_PUT_STRING(msg, NL80211_ATTR_IFNAME, mondevice); + NLA_PUT_U32(msg, NL80211_ATTR_IFTYPE, NL80211_IFTYPE_MONITOR); + + err = nl_send_auto_complete(state->nl_sock, msg); + if (err < 0) { +#if defined HAVE_LIBNL_NLE + if (err == -NLE_FAILURE) { +#else + if (err == -ENFILE) { +#endif + /* + * Device not available; our caller should just + * keep trying. (libnl 2.x maps ENFILE to + * NLE_FAILURE; it can also map other errors + * to that, but there's not much we can do + * about that.) + */ + nlmsg_free(msg); + return 0; + } else { + /* + * Real failure, not just "that device is not + * available. + */ + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_send_auto_complete failed adding %s interface: %s", + device, mondevice, get_nl_errmsg(-err)); + nlmsg_free(msg); + return PCAP_ERROR; + } + } + err = nl_wait_for_ack(state->nl_sock); + if (err < 0) { +#if defined HAVE_LIBNL_NLE + if (err == -NLE_FAILURE) { +#else + if (err == -ENFILE) { +#endif + /* + * Device not available; our caller should just + * keep trying. (libnl 2.x maps ENFILE to + * NLE_FAILURE; it can also map other errors + * to that, but there's not much we can do + * about that.) + */ + nlmsg_free(msg); + return 0; + } else { + /* + * Real failure, not just "that device is not + * available. + */ + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_wait_for_ack failed adding %s interface: %s", + device, mondevice, get_nl_errmsg(-err)); + nlmsg_free(msg); + return PCAP_ERROR; + } + } + + /* + * Success. + */ + nlmsg_free(msg); + + /* + * Try to remember the monitor device. + */ + handlep->mondevice = strdup(mondevice); + if (handlep->mondevice == NULL) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "strdup"); + /* + * Get rid of the monitor device. + */ + del_mon_if(handle, sock_fd, state, device, mondevice); + return PCAP_ERROR; + } + return 1; + +nla_put_failure: + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_put failed adding %s interface", + device, mondevice); + nlmsg_free(msg); + return PCAP_ERROR; +} + +static int +del_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state, + const char *device, const char *mondevice) +{ + int ifindex; + struct nl_msg *msg; + int err; + + ifindex = iface_get_id(sock_fd, mondevice, handle->errbuf); + if (ifindex == -1) + return PCAP_ERROR; + + msg = nlmsg_alloc(); + if (!msg) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: failed to allocate netlink msg", device); + return PCAP_ERROR; + } + + genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0, + 0, NL80211_CMD_DEL_INTERFACE, 0); + NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex); + + err = nl_send_auto_complete(state->nl_sock, msg); + if (err < 0) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_send_auto_complete failed deleting %s interface: %s", + device, mondevice, get_nl_errmsg(-err)); + nlmsg_free(msg); + return PCAP_ERROR; + } + err = nl_wait_for_ack(state->nl_sock); + if (err < 0) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_wait_for_ack failed adding %s interface: %s", + device, mondevice, get_nl_errmsg(-err)); + nlmsg_free(msg); + return PCAP_ERROR; + } + + /* + * Success. + */ + nlmsg_free(msg); + return 1; + +nla_put_failure: + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_put failed deleting %s interface", + device, mondevice); + nlmsg_free(msg); + return PCAP_ERROR; +} + +static int +enter_rfmon_mode_mac80211(pcap_t *handle, int sock_fd, const char *device) +{ + struct pcap_linux *handlep = handle->priv; + int ret; + char phydev_path[PATH_MAX+1]; + struct nl80211_state nlstate; + struct ifreq ifr; + u_int n; + + /* + * Is this a mac80211 device? + */ + ret = get_mac80211_phydev(handle, device, phydev_path, PATH_MAX); + if (ret < 0) + return ret; /* error */ + if (ret == 0) + return 0; /* no error, but not mac80211 device */ + + /* + * XXX - is this already a monN device? + * If so, we're done. + * Is that determined by old Wireless Extensions ioctls? + */ + + /* + * OK, it's apparently a mac80211 device. + * Try to find an unused monN device for it. + */ + ret = nl80211_init(handle, &nlstate, device); + if (ret != 0) + return ret; + for (n = 0; n < UINT_MAX; n++) { + /* + * Try mon{n}. + */ + char mondevice[3+10+1]; /* mon{UINT_MAX}\0 */ + + pcap_snprintf(mondevice, sizeof mondevice, "mon%u", n); + ret = add_mon_if(handle, sock_fd, &nlstate, device, mondevice); + if (ret == 1) { + /* + * Success. We don't clean up the libnl state + * yet, as we'll be using it later. + */ + goto added; + } + if (ret < 0) { + /* + * Hard failure. Just return ret; handle->errbuf + * has already been set. + */ + nl80211_cleanup(&nlstate); + return ret; + } + } + + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: No free monN interfaces", device); + nl80211_cleanup(&nlstate); + return PCAP_ERROR; + +added: + +#if 0 + /* + * Sleep for .1 seconds. + */ + delay.tv_sec = 0; + delay.tv_nsec = 500000000; + nanosleep(&delay, NULL); +#endif + + /* + * If we haven't already done so, arrange to have + * "pcap_close_all()" called when we exit. + */ + if (!pcap_do_addexit(handle)) { + /* + * "atexit()" failed; don't put the interface + * in rfmon mode, just give up. + */ + del_mon_if(handle, sock_fd, &nlstate, device, + handlep->mondevice); + nl80211_cleanup(&nlstate); + return PCAP_ERROR; + } + + /* + * Now configure the monitor interface up. + */ + memset(&ifr, 0, sizeof(ifr)); + pcap_strlcpy(ifr.ifr_name, handlep->mondevice, sizeof(ifr.ifr_name)); + if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "%s: Can't get flags for %s", device, + handlep->mondevice); + del_mon_if(handle, sock_fd, &nlstate, device, + handlep->mondevice); + nl80211_cleanup(&nlstate); + return PCAP_ERROR; + } + ifr.ifr_flags |= IFF_UP|IFF_RUNNING; + if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "%s: Can't set flags for %s", device, + handlep->mondevice); + del_mon_if(handle, sock_fd, &nlstate, device, + handlep->mondevice); + nl80211_cleanup(&nlstate); + return PCAP_ERROR; + } + + /* + * Success. Clean up the libnl state. + */ + nl80211_cleanup(&nlstate); + + /* + * Note that we have to delete the monitor device when we close + * the handle. + */ + handlep->must_do_on_close |= MUST_DELETE_MONIF; + + /* + * Add this to the list of pcaps to close when we exit. + */ + pcap_add_to_pcaps_to_close(handle); + + return 1; +} +#endif /* HAVE_LIBNL */ + +#ifdef IW_MODE_MONITOR +/* + * Bonding devices mishandle unknown ioctls; they fail with ENODEV + * rather than ENOTSUP, EOPNOTSUPP, or ENOTTY, so Wireless Extensions + * will fail with ENODEV if we try to do them on a bonding device, + * making us return a "no such device" indication rather than just + * saying "no Wireless Extensions". + * + * So we check for bonding devices, if we can, before trying those + * ioctls, by trying a bonding device information query ioctl to see + * whether it succeeds. + */ +static int +is_bonding_device(int fd, const char *device) +{ +#ifdef BOND_INFO_QUERY_IOCTL + struct ifreq ifr; + ifbond ifb; + + memset(&ifr, 0, sizeof ifr); + pcap_strlcpy(ifr.ifr_name, device, sizeof ifr.ifr_name); + memset(&ifb, 0, sizeof ifb); + ifr.ifr_data = (caddr_t)&ifb; + if (ioctl(fd, BOND_INFO_QUERY_IOCTL, &ifr) == 0) + return 1; /* success, so it's a bonding device */ +#endif /* BOND_INFO_QUERY_IOCTL */ + + return 0; /* no, it's not a bonding device */ +} +#endif /* IW_MODE_MONITOR */ + +static int pcap_protocol(pcap_t *handle) +{ + int protocol; + + protocol = handle->opt.protocol; + if (protocol == 0) + protocol = ETH_P_ALL; + + return htons(protocol); +} + +static int +pcap_can_set_rfmon_linux(pcap_t *handle) +{ +#ifdef HAVE_LIBNL + char phydev_path[PATH_MAX+1]; + int ret; +#endif +#ifdef IW_MODE_MONITOR + int sock_fd; + struct iwreq ireq; +#endif + + if (strcmp(handle->opt.device, "any") == 0) { + /* + * Monitor mode makes no sense on the "any" device. + */ + return 0; + } + +#ifdef HAVE_LIBNL + /* + * Bleah. There doesn't seem to be a way to ask a mac80211 + * device, through libnl, whether it supports monitor mode; + * we'll just check whether the device appears to be a + * mac80211 device and, if so, assume the device supports + * monitor mode. + * + * wmaster devices don't appear to support the Wireless + * Extensions, but we can create a mon device for a + * wmaster device, so we don't bother checking whether + * a mac80211 device supports the Wireless Extensions. + */ + ret = get_mac80211_phydev(handle, handle->opt.device, phydev_path, + PATH_MAX); + if (ret < 0) + return ret; /* error */ + if (ret == 1) + return 1; /* mac80211 device */ +#endif + +#ifdef IW_MODE_MONITOR + /* + * Bleah. There doesn't appear to be an ioctl to use to ask + * whether a device supports monitor mode; we'll just do + * SIOCGIWMODE and, if it succeeds, assume the device supports + * monitor mode. + * + * Open a socket on which to attempt to get the mode. + * (We assume that if we have Wireless Extensions support + * we also have PF_PACKET support.) + */ + sock_fd = socket(PF_PACKET, SOCK_RAW, pcap_protocol(handle)); + if (sock_fd == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "socket"); + return PCAP_ERROR; + } + + if (is_bonding_device(sock_fd, handle->opt.device)) { + /* It's a bonding device, so don't even try. */ + close(sock_fd); + return 0; + } + + /* + * Attempt to get the current mode. + */ + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, handle->opt.device, + sizeof ireq.ifr_ifrn.ifrn_name); + if (ioctl(sock_fd, SIOCGIWMODE, &ireq) != -1) { + /* + * Well, we got the mode; assume we can set it. + */ + close(sock_fd); + return 1; + } + if (errno == ENODEV) { + /* The device doesn't even exist. */ + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "SIOCGIWMODE failed"); + close(sock_fd); + return PCAP_ERROR_NO_SUCH_DEVICE; + } + close(sock_fd); +#endif + return 0; +} + +/* + * Grabs the number of dropped packets by the interface from /proc/net/dev. + * + * XXX - what about /sys/class/net/{interface name}/rx_*? There are + * individual devices giving, in ASCII, various rx_ and tx_ statistics. + * + * Or can we get them in binary form from netlink? + */ +static long int +linux_if_drops(const char * if_name) +{ + char buffer[512]; + FILE *file; + char *bufptr, *nameptr, *colonptr; + int field_to_convert = 3; + long int dropped_pkts = 0; + + file = fopen("/proc/net/dev", "r"); + if (!file) + return 0; + + while (fgets(buffer, sizeof(buffer), file) != NULL) + { + /* search for 'bytes' -- if its in there, then + that means we need to grab the fourth field. otherwise + grab the third field. */ + if (field_to_convert != 4 && strstr(buffer, "bytes")) + { + field_to_convert = 4; + continue; + } + + /* + * See whether this line corresponds to this device. + * The line should have zero or more leading blanks, + * followed by a device name, followed by a colon, + * followed by the statistics. + */ + bufptr = buffer; + /* Skip leading blanks */ + while (*bufptr == ' ') + bufptr++; + nameptr = bufptr; + /* Look for the colon */ + colonptr = strchr(nameptr, ':'); + if (colonptr == NULL) + { + /* + * Not found; this could, for example, be the + * header line. + */ + continue; + } + /* Null-terminate the interface name. */ + *colonptr = '\0'; + if (strcmp(if_name, nameptr) == 0) + { + /* + * OK, this line has the statistics for the interface. + * Skip past the interface name. + */ + bufptr = colonptr + 1; + + /* grab the nth field from it */ + while (--field_to_convert && *bufptr != '\0') + { + /* + * This isn't the field we want. + * First, skip any leading blanks before + * the field. + */ + while (*bufptr == ' ') + bufptr++; + + /* + * Now skip the non-blank characters of + * the field. + */ + while (*bufptr != '\0' && *bufptr != ' ') + bufptr++; + } + + if (field_to_convert == 0) + { + /* + * We've found the field we want. + * Skip any leading blanks before it. + */ + while (*bufptr == ' ') + bufptr++; + + /* + * Now extract the value, if we have one. + */ + if (*bufptr != '\0') + dropped_pkts = strtol(bufptr, NULL, 10); + } + break; + } + } + + fclose(file); + return dropped_pkts; +} + + +/* + * With older kernels promiscuous mode is kind of interesting because we + * have to reset the interface before exiting. The problem can't really + * be solved without some daemon taking care of managing usage counts. + * If we put the interface into promiscuous mode, we set a flag indicating + * that we must take it out of that mode when the interface is closed, + * and, when closing the interface, if that flag is set we take it out + * of promiscuous mode. + * + * Even with newer kernels, we have the same issue with rfmon mode. + */ + +static void pcap_cleanup_linux( pcap_t *handle ) +{ + struct pcap_linux *handlep = handle->priv; + struct ifreq ifr; +#ifdef HAVE_LIBNL + struct nl80211_state nlstate; + int ret; +#endif /* HAVE_LIBNL */ +#ifdef IW_MODE_MONITOR + int oldflags; + struct iwreq ireq; +#endif /* IW_MODE_MONITOR */ + + if (handlep->must_do_on_close != 0) { + /* + * There's something we have to do when closing this + * pcap_t. + */ + if (handlep->must_do_on_close & MUST_CLEAR_PROMISC) { + /* + * We put the interface into promiscuous mode; + * take it out of promiscuous mode. + * + * XXX - if somebody else wants it in promiscuous + * mode, this code cannot know that, so it'll take + * it out of promiscuous mode. That's not fixable + * in 2.0[.x] kernels. + */ + memset(&ifr, 0, sizeof(ifr)); + pcap_strlcpy(ifr.ifr_name, handlep->device, + sizeof(ifr.ifr_name)); + if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) { + fprintf(stderr, + "Can't restore interface %s flags (SIOCGIFFLAGS failed: %s).\n" + "Please adjust manually.\n" + "Hint: This can't happen with Linux >= 2.2.0.\n", + handlep->device, strerror(errno)); + } else { + if (ifr.ifr_flags & IFF_PROMISC) { + /* + * Promiscuous mode is currently on; + * turn it off. + */ + ifr.ifr_flags &= ~IFF_PROMISC; + if (ioctl(handle->fd, SIOCSIFFLAGS, + &ifr) == -1) { + fprintf(stderr, + "Can't restore interface %s flags (SIOCSIFFLAGS failed: %s).\n" + "Please adjust manually.\n" + "Hint: This can't happen with Linux >= 2.2.0.\n", + handlep->device, + strerror(errno)); + } + } + } + } + +#ifdef HAVE_LIBNL + if (handlep->must_do_on_close & MUST_DELETE_MONIF) { + ret = nl80211_init(handle, &nlstate, handlep->device); + if (ret >= 0) { + ret = del_mon_if(handle, handle->fd, &nlstate, + handlep->device, handlep->mondevice); + nl80211_cleanup(&nlstate); + } + if (ret < 0) { + fprintf(stderr, + "Can't delete monitor interface %s (%s).\n" + "Please delete manually.\n", + handlep->mondevice, handle->errbuf); + } + } +#endif /* HAVE_LIBNL */ + +#ifdef IW_MODE_MONITOR + if (handlep->must_do_on_close & MUST_CLEAR_RFMON) { + /* + * We put the interface into rfmon mode; + * take it out of rfmon mode. + * + * XXX - if somebody else wants it in rfmon + * mode, this code cannot know that, so it'll take + * it out of rfmon mode. + */ + + /* + * First, take the interface down if it's up; + * otherwise, we might get EBUSY. + * If we get errors, just drive on and print + * a warning if we can't restore the mode. + */ + oldflags = 0; + memset(&ifr, 0, sizeof(ifr)); + pcap_strlcpy(ifr.ifr_name, handlep->device, + sizeof(ifr.ifr_name)); + if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) != -1) { + if (ifr.ifr_flags & IFF_UP) { + oldflags = ifr.ifr_flags; + ifr.ifr_flags &= ~IFF_UP; + if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) + oldflags = 0; /* didn't set, don't restore */ + } + } + + /* + * Now restore the mode. + */ + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, handlep->device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.u.mode = handlep->oldmode; + if (ioctl(handle->fd, SIOCSIWMODE, &ireq) == -1) { + /* + * Scientist, you've failed. + */ + fprintf(stderr, + "Can't restore interface %s wireless mode (SIOCSIWMODE failed: %s).\n" + "Please adjust manually.\n", + handlep->device, strerror(errno)); + } + + /* + * Now bring the interface back up if we brought + * it down. + */ + if (oldflags != 0) { + ifr.ifr_flags = oldflags; + if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) { + fprintf(stderr, + "Can't bring interface %s back up (SIOCSIFFLAGS failed: %s).\n" + "Please adjust manually.\n", + handlep->device, strerror(errno)); + } + } + } +#endif /* IW_MODE_MONITOR */ + + /* + * Take this pcap out of the list of pcaps for which we + * have to take the interface out of some mode. + */ + pcap_remove_from_pcaps_to_close(handle); + } + + if (handlep->mondevice != NULL) { + free(handlep->mondevice); + handlep->mondevice = NULL; + } + if (handlep->device != NULL) { + free(handlep->device); + handlep->device = NULL; + } + pcap_cleanup_live_common(handle); +} + +/* + * Set the timeout to be used in poll() with memory-mapped packet capture. + */ +static void +set_poll_timeout(struct pcap_linux *handlep) +{ +#ifdef HAVE_TPACKET3 + struct utsname utsname; + char *version_component, *endp; + int major, minor; + int broken_tpacket_v3 = 1; + + /* + * Some versions of TPACKET_V3 have annoying bugs/misfeatures + * around which we have to work. Determine if we have those + * problems or not. + */ + if (uname(&utsname) == 0) { + /* + * 3.19 is the first release with a fixed version of + * TPACKET_V3. We treat anything before that as + * not haveing a fixed version; that may really mean + * it has *no* version. + */ + version_component = utsname.release; + major = strtol(version_component, &endp, 10); + if (endp != version_component && *endp == '.') { + /* + * OK, that was a valid major version. + * Get the minor version. + */ + version_component = endp + 1; + minor = strtol(version_component, &endp, 10); + if (endp != version_component && + (*endp == '.' || *endp == '\0')) { + /* + * OK, that was a valid minor version. + * Is this 3.19 or newer? + */ + if (major >= 4 || (major == 3 && minor >= 19)) { + /* Yes. TPACKET_V3 works correctly. */ + broken_tpacket_v3 = 0; + } + } + } + } +#endif + if (handlep->timeout == 0) { +#ifdef HAVE_TPACKET3 + /* + * XXX - due to a set of (mis)features in the TPACKET_V3 + * kernel code prior to the 3.19 kernel, blocking forever + * with a TPACKET_V3 socket can, if few packets are + * arriving and passing the socket filter, cause most + * packets to be dropped. See libpcap issue #335 for the + * full painful story. + * + * The workaround is to have poll() time out very quickly, + * so we grab the frames handed to us, and return them to + * the kernel, ASAP. + */ + if (handlep->tp_version == TPACKET_V3 && broken_tpacket_v3) + handlep->poll_timeout = 1; /* don't block for very long */ + else +#endif + handlep->poll_timeout = -1; /* block forever */ + } else if (handlep->timeout > 0) { +#ifdef HAVE_TPACKET3 + /* + * For TPACKET_V3, the timeout is handled by the kernel, + * so block forever; that way, we don't get extra timeouts. + * Don't do that if we have a broken TPACKET_V3, though. + */ + if (handlep->tp_version == TPACKET_V3 && !broken_tpacket_v3) + handlep->poll_timeout = -1; /* block forever, let TPACKET_V3 wake us up */ + else +#endif + handlep->poll_timeout = handlep->timeout; /* block for that amount of time */ + } else { + /* + * Non-blocking mode; we call poll() to pick up error + * indications, but we don't want it to wait for + * anything. + */ + handlep->poll_timeout = 0; + } +} + +/* + * Get a handle for a live capture from the given device. You can + * pass NULL as device to get all packages (without link level + * information of course). If you pass 1 as promisc the interface + * will be set to promiscous mode (XXX: I think this usage should + * be deprecated and functions be added to select that later allow + * modification of that values -- Torsten). + */ +static int +pcap_activate_linux(pcap_t *handle) +{ + struct pcap_linux *handlep = handle->priv; + const char *device; + struct ifreq ifr; + int status = 0; + int ret; + + device = handle->opt.device; + + /* + * Make sure the name we were handed will fit into the ioctls we + * might perform on the device; if not, return a "No such device" + * indication, as the Linux kernel shouldn't support creating + * a device whose name won't fit into those ioctls. + * + * "Will fit" means "will fit, complete with a null terminator", + * so if the length, which does *not* include the null terminator, + * is greater than *or equal to* the size of the field into which + * we'll be copying it, that won't fit. + */ + if (strlen(device) >= sizeof(ifr.ifr_name)) { + status = PCAP_ERROR_NO_SUCH_DEVICE; + goto fail; + } + + /* + * Turn a negative snapshot value (invalid), a snapshot value of + * 0 (unspecified), or a value bigger than the normal maximum + * value, into the maximum allowed value. + * + * If some application really *needs* a bigger snapshot + * length, we should just increase MAXIMUM_SNAPLEN. + */ + if (handle->snapshot <= 0 || handle->snapshot > MAXIMUM_SNAPLEN) + handle->snapshot = MAXIMUM_SNAPLEN; + + handle->inject_op = pcap_inject_linux; + handle->setfilter_op = pcap_setfilter_linux; + handle->setdirection_op = pcap_setdirection_linux; + handle->set_datalink_op = pcap_set_datalink_linux; + handle->getnonblock_op = pcap_getnonblock_fd; + handle->setnonblock_op = pcap_setnonblock_fd; + handle->cleanup_op = pcap_cleanup_linux; + handle->read_op = pcap_read_linux; + handle->stats_op = pcap_stats_linux; + + /* + * The "any" device is a special device which causes us not + * to bind to a particular device and thus to look at all + * devices. + */ + if (strcmp(device, "any") == 0) { + if (handle->opt.promisc) { + handle->opt.promisc = 0; + /* Just a warning. */ + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "Promiscuous mode not supported on the \"any\" device"); + status = PCAP_WARNING_PROMISC_NOTSUP; + } + } + + handlep->device = strdup(device); + if (handlep->device == NULL) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "strdup"); + status = PCAP_ERROR; + goto fail; + } + + /* copy timeout value */ + handlep->timeout = handle->opt.timeout; + + /* + * If we're in promiscuous mode, then we probably want + * to see when the interface drops packets too, so get an + * initial count from /proc/net/dev + */ + if (handle->opt.promisc) + handlep->proc_dropped = linux_if_drops(handlep->device); + + /* + * Current Linux kernels use the protocol family PF_PACKET to + * allow direct access to all packets on the network while + * older kernels had a special socket type SOCK_PACKET to + * implement this feature. + * While this old implementation is kind of obsolete we need + * to be compatible with older kernels for a while so we are + * trying both methods with the newer method preferred. + */ + ret = activate_new(handle); + if (ret < 0) { + /* + * Fatal error with the new way; just fail. + * ret has the error return; if it's PCAP_ERROR, + * handle->errbuf has been set appropriately. + */ + status = ret; + goto fail; + } + if (ret == 1) { + /* + * Success. + * Try to use memory-mapped access. + */ + switch (activate_mmap(handle, &status)) { + + case 1: + /* + * We succeeded. status has been + * set to the status to return, + * which might be 0, or might be + * a PCAP_WARNING_ value. + * + * Set the timeout to use in poll() before + * returning. + */ + set_poll_timeout(handlep); + return status; + + case 0: + /* + * Kernel doesn't support it - just continue + * with non-memory-mapped access. + */ + break; + + case -1: + /* + * We failed to set up to use it, or the kernel + * supports it, but we failed to enable it. + * status has been set to the error status to + * return and, if it's PCAP_ERROR, handle->errbuf + * contains the error message. + */ + goto fail; + } + } + else if (ret == 0) { + /* Non-fatal error; try old way */ + if ((ret = activate_old(handle)) != 1) { + /* + * Both methods to open the packet socket failed. + * Tidy up and report our failure (handle->errbuf + * is expected to be set by the functions above). + */ + status = ret; + goto fail; + } + } + + /* + * We set up the socket, but not with memory-mapped access. + */ + if (handle->opt.buffer_size != 0) { + /* + * Set the socket buffer size to the specified value. + */ + if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, + &handle->opt.buffer_size, + sizeof(handle->opt.buffer_size)) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "SO_RCVBUF"); + status = PCAP_ERROR; + goto fail; + } + } + + /* Allocate the buffer */ + + handle->buffer = malloc(handle->bufsize + handle->offset); + if (!handle->buffer) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "malloc"); + status = PCAP_ERROR; + goto fail; + } + + /* + * "handle->fd" is a socket, so "select()" and "poll()" + * should work on it. + */ + handle->selectable_fd = handle->fd; + + return status; + +fail: + pcap_cleanup_linux(handle); + return status; +} + +/* + * Read at most max_packets from the capture stream and call the callback + * for each of them. Returns the number of packets handled or -1 if an + * error occured. + */ +static int +pcap_read_linux(pcap_t *handle, int max_packets _U_, pcap_handler callback, u_char *user) +{ + /* + * Currently, on Linux only one packet is delivered per read, + * so we don't loop. + */ + return pcap_read_packet(handle, callback, user); +} + +static int +pcap_set_datalink_linux(pcap_t *handle, int dlt) +{ + handle->linktype = dlt; + return 0; +} + +/* + * linux_check_direction() + * + * Do checks based on packet direction. + */ +static inline int +linux_check_direction(const pcap_t *handle, const struct sockaddr_ll *sll) +{ + struct pcap_linux *handlep = handle->priv; + + if (sll->sll_pkttype == PACKET_OUTGOING) { + /* + * Outgoing packet. + * If this is from the loopback device, reject it; + * we'll see the packet as an incoming packet as well, + * and we don't want to see it twice. + */ + if (sll->sll_ifindex == handlep->lo_ifindex) + return 0; + + /* + * If this is an outgoing CAN or CAN FD frame, and + * the user doesn't only want outgoing packets, + * reject it; CAN devices and drivers, and the CAN + * stack, always arrange to loop back transmitted + * packets, so they also appear as incoming packets. + * We don't want duplicate packets, and we can't + * easily distinguish packets looped back by the CAN + * layer than those received by the CAN layer, so we + * eliminate this packet instead. + */ + if ((sll->sll_protocol == LINUX_SLL_P_CAN || + sll->sll_protocol == LINUX_SLL_P_CANFD) && + handle->direction != PCAP_D_OUT) + return 0; + + /* + * If the user only wants incoming packets, reject it. + */ + if (handle->direction == PCAP_D_IN) + return 0; + } else { + /* + * Incoming packet. + * If the user only wants outgoing packets, reject it. + */ + if (handle->direction == PCAP_D_OUT) + return 0; + } + return 1; +} + +/* + * Read a packet from the socket calling the handler provided by + * the user. Returns the number of packets received or -1 if an + * error occured. + */ +static int +pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata) +{ + struct pcap_linux *handlep = handle->priv; + u_char *bp; + int offset; +#ifdef HAVE_PF_PACKET_SOCKETS + struct sockaddr_ll from; +#else + struct sockaddr from; +#endif +#if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_STRUCT_TPACKET_AUXDATA_TP_VLAN_TCI) + struct iovec iov; + struct msghdr msg; + struct cmsghdr *cmsg; + union { + struct cmsghdr cmsg; + char buf[CMSG_SPACE(sizeof(struct tpacket_auxdata))]; + } cmsg_buf; +#else /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_STRUCT_TPACKET_AUXDATA_TP_VLAN_TCI) */ + socklen_t fromlen; +#endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_STRUCT_TPACKET_AUXDATA_TP_VLAN_TCI) */ + int packet_len, caplen; + struct pcap_pkthdr pcap_header; + + struct bpf_aux_data aux_data; +#ifdef HAVE_PF_PACKET_SOCKETS + /* + * If this is a cooked device, leave extra room for a + * fake packet header. + */ + if (handlep->cooked) { + if (handle->linktype == DLT_LINUX_SLL2) + offset = SLL2_HDR_LEN; + else + offset = SLL_HDR_LEN; + } else + offset = 0; +#else + /* + * This system doesn't have PF_PACKET sockets, so it doesn't + * support cooked devices. + */ + offset = 0; +#endif + + /* + * Receive a single packet from the kernel. + * We ignore EINTR, as that might just be due to a signal + * being delivered - if the signal should interrupt the + * loop, the signal handler should call pcap_breakloop() + * to set handle->break_loop (we ignore it on other + * platforms as well). + * We also ignore ENETDOWN, so that we can continue to + * capture traffic if the interface goes down and comes + * back up again; comments in the kernel indicate that + * we'll just block waiting for packets if we try to + * receive from a socket that delivered ENETDOWN, and, + * if we're using a memory-mapped buffer, we won't even + * get notified of "network down" events. + */ + bp = (u_char *)handle->buffer + handle->offset; + +#if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_STRUCT_TPACKET_AUXDATA_TP_VLAN_TCI) + msg.msg_name = &from; + msg.msg_namelen = sizeof(from); + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = &cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + msg.msg_flags = 0; + + iov.iov_len = handle->bufsize - offset; + iov.iov_base = bp + offset; +#endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_STRUCT_TPACKET_AUXDATA_TP_VLAN_TCI) */ + + do { + /* + * Has "pcap_breakloop()" been called? + */ + if (handle->break_loop) { + /* + * Yes - clear the flag that indicates that it has, + * and return PCAP_ERROR_BREAK as an indication that + * we were told to break out of the loop. + */ + handle->break_loop = 0; + return PCAP_ERROR_BREAK; + } + +#if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_STRUCT_TPACKET_AUXDATA_TP_VLAN_TCI) + packet_len = recvmsg(handle->fd, &msg, MSG_TRUNC); +#else /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_STRUCT_TPACKET_AUXDATA_TP_VLAN_TCI) */ + fromlen = sizeof(from); + packet_len = recvfrom( + handle->fd, bp + offset, + handle->bufsize - offset, MSG_TRUNC, + (struct sockaddr *) &from, &fromlen); +#endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_STRUCT_TPACKET_AUXDATA_TP_VLAN_TCI) */ + } while (packet_len == -1 && errno == EINTR); + + /* Check if an error occured */ + + if (packet_len == -1) { + switch (errno) { + + case EAGAIN: + return 0; /* no packet there */ + + case ENETDOWN: + /* + * The device on which we're capturing went away. + * + * XXX - we should really return + * PCAP_ERROR_IFACE_NOT_UP, but pcap_dispatch() + * etc. aren't defined to return that. + */ + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "The interface went down"); + return PCAP_ERROR; + + default: + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "recvfrom"); + return PCAP_ERROR; + } + } + +#ifdef HAVE_PF_PACKET_SOCKETS + if (!handlep->sock_packet) { + /* + * Unfortunately, there is a window between socket() and + * bind() where the kernel may queue packets from any + * interface. If we're bound to a particular interface, + * discard packets not from that interface. + * + * (If socket filters are supported, we could do the + * same thing we do when changing the filter; however, + * that won't handle packet sockets without socket + * filter support, and it's a bit more complicated. + * It would save some instructions per packet, however.) + */ + if (handlep->ifindex != -1 && + from.sll_ifindex != handlep->ifindex) + return 0; + + /* + * Do checks based on packet direction. + * We can only do this if we're using PF_PACKET; the + * address returned for SOCK_PACKET is a "sockaddr_pkt" + * which lacks the relevant packet type information. + */ + if (!linux_check_direction(handle, &from)) + return 0; + } +#endif + +#ifdef HAVE_PF_PACKET_SOCKETS + /* + * If this is a cooked device, fill in the fake packet header. + */ + if (handlep->cooked) { + /* + * Add the length of the fake header to the length + * of packet data we read. + */ + if (handle->linktype == DLT_LINUX_SLL2) { + struct sll2_header *hdrp; + + packet_len += SLL2_HDR_LEN; + + hdrp = (struct sll2_header *)bp; + hdrp->sll2_protocol = from.sll_protocol; + hdrp->sll2_reserved_mbz = 0; + hdrp->sll2_if_index = htonl(from.sll_ifindex); + hdrp->sll2_hatype = htons(from.sll_hatype); + hdrp->sll2_pkttype = from.sll_pkttype; + hdrp->sll2_halen = from.sll_halen; + memcpy(hdrp->sll2_addr, from.sll_addr, + (from.sll_halen > SLL_ADDRLEN) ? + SLL_ADDRLEN : + from.sll_halen); + } else { + struct sll_header *hdrp; + + packet_len += SLL_HDR_LEN; + + hdrp = (struct sll_header *)bp; + hdrp->sll_pkttype = htons(from.sll_pkttype); + hdrp->sll_hatype = htons(from.sll_hatype); + hdrp->sll_halen = htons(from.sll_halen); + memcpy(hdrp->sll_addr, from.sll_addr, + (from.sll_halen > SLL_ADDRLEN) ? + SLL_ADDRLEN : + from.sll_halen); + hdrp->sll_protocol = from.sll_protocol; + } + } + + /* + * Start out with no VLAN information. + */ + aux_data.vlan_tag_present = 0; + aux_data.vlan_tag = 0; +#if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_STRUCT_TPACKET_AUXDATA_TP_VLAN_TCI) + if (handlep->vlan_offset != -1) { + for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) { + struct tpacket_auxdata *aux; + unsigned int len; + struct vlan_tag *tag; + + if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct tpacket_auxdata)) || + cmsg->cmsg_level != SOL_PACKET || + cmsg->cmsg_type != PACKET_AUXDATA) { + /* + * This isn't a PACKET_AUXDATA auxiliary + * data item. + */ + continue; + } + + aux = (struct tpacket_auxdata *)CMSG_DATA(cmsg); + if (!VLAN_VALID(aux, aux)) { + /* + * There is no VLAN information in the + * auxiliary data. + */ + continue; + } + + len = (u_int)packet_len > iov.iov_len ? iov.iov_len : (u_int)packet_len; + if (len < (u_int)handlep->vlan_offset) + break; + + /* + * Move everything in the header, except the + * type field, down VLAN_TAG_LEN bytes, to + * allow us to insert the VLAN tag between + * that stuff and the type field. + */ + bp -= VLAN_TAG_LEN; + memmove(bp, bp + VLAN_TAG_LEN, handlep->vlan_offset); + + /* + * Now insert the tag. + */ + tag = (struct vlan_tag *)(bp + handlep->vlan_offset); + tag->vlan_tpid = htons(VLAN_TPID(aux, aux)); + tag->vlan_tci = htons(aux->tp_vlan_tci); + + /* + * Save a flag indicating that we have a VLAN tag, + * and the VLAN TCI, to bpf_aux_data struct for + * use by the BPF filter if we're doing the + * filtering in userland. + */ + aux_data.vlan_tag_present = 1; + aux_data.vlan_tag = htons(aux->tp_vlan_tci) & 0x0fff; + + /* + * Add the tag to the packet lengths. + */ + packet_len += VLAN_TAG_LEN; + } + } +#endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_STRUCT_TPACKET_AUXDATA_TP_VLAN_TCI) */ +#endif /* HAVE_PF_PACKET_SOCKETS */ + + /* + * XXX: According to the kernel source we should get the real + * packet len if calling recvfrom with MSG_TRUNC set. It does + * not seem to work here :(, but it is supported by this code + * anyway. + * To be honest the code RELIES on that feature so this is really + * broken with 2.2.x kernels. + * I spend a day to figure out what's going on and I found out + * that the following is happening: + * + * The packet comes from a random interface and the packet_rcv + * hook is called with a clone of the packet. That code inserts + * the packet into the receive queue of the packet socket. + * If a filter is attached to that socket that filter is run + * first - and there lies the problem. The default filter always + * cuts the packet at the snaplen: + * + * # tcpdump -d + * (000) ret #68 + * + * So the packet filter cuts down the packet. The recvfrom call + * says "hey, it's only 68 bytes, it fits into the buffer" with + * the result that we don't get the real packet length. This + * is valid at least until kernel 2.2.17pre6. + * + * We currently handle this by making a copy of the filter + * program, fixing all "ret" instructions with non-zero + * operands to have an operand of MAXIMUM_SNAPLEN so that the + * filter doesn't truncate the packet, and supplying that modified + * filter to the kernel. + */ + + caplen = packet_len; + if (caplen > handle->snapshot) + caplen = handle->snapshot; + + /* Run the packet filter if not using kernel filter */ + if (handlep->filter_in_userland && handle->fcode.bf_insns) { + if (bpf_filter_with_aux_data(handle->fcode.bf_insns, bp, + packet_len, caplen, &aux_data) == 0) { + /* rejected by filter */ + return 0; + } + } + + /* Fill in our own header data */ + + /* get timestamp for this packet */ +#if defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS) + if (handle->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO) { + if (ioctl(handle->fd, SIOCGSTAMPNS, &pcap_header.ts) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "SIOCGSTAMPNS"); + return PCAP_ERROR; + } + } else +#endif + { + if (ioctl(handle->fd, SIOCGSTAMP, &pcap_header.ts) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "SIOCGSTAMP"); + return PCAP_ERROR; + } + } + + pcap_header.caplen = caplen; + pcap_header.len = packet_len; + + /* + * Count the packet. + * + * Arguably, we should count them before we check the filter, + * as on many other platforms "ps_recv" counts packets + * handed to the filter rather than packets that passed + * the filter, but if filtering is done in the kernel, we + * can't get a count of packets that passed the filter, + * and that would mean the meaning of "ps_recv" wouldn't + * be the same on all Linux systems. + * + * XXX - it's not the same on all systems in any case; + * ideally, we should have a "get the statistics" call + * that supplies more counts and indicates which of them + * it supplies, so that we supply a count of packets + * handed to the filter only on platforms where that + * information is available. + * + * We count them here even if we can get the packet count + * from the kernel, as we can only determine at run time + * whether we'll be able to get it from the kernel (if + * HAVE_STRUCT_TPACKET_STATS isn't defined, we can't get it from + * the kernel, but if it is defined, the library might + * have been built with a 2.4 or later kernel, but we + * might be running on a 2.2[.x] kernel without Alexey + * Kuznetzov's turbopacket patches, and thus the kernel + * might not be able to supply those statistics). We + * could, I guess, try, when opening the socket, to get + * the statistics, and if we can not increment the count + * here, but it's not clear that always incrementing + * the count is more expensive than always testing a flag + * in memory. + * + * We keep the count in "handlep->packets_read", and use that + * for "ps_recv" if we can't get the statistics from the kernel. + * We do that because, if we *can* get the statistics from + * the kernel, we use "handlep->stat.ps_recv" and + * "handlep->stat.ps_drop" as running counts, as reading the + * statistics from the kernel resets the kernel statistics, + * and if we directly increment "handlep->stat.ps_recv" here, + * that means it will count packets *twice* on systems where + * we can get kernel statistics - once here, and once in + * pcap_stats_linux(). + */ + handlep->packets_read++; + + /* Call the user supplied callback function */ + callback(userdata, &pcap_header, bp); + + return 1; +} + +static int +pcap_inject_linux(pcap_t *handle, const void *buf, size_t size) +{ + struct pcap_linux *handlep = handle->priv; + int ret; + +#ifdef HAVE_PF_PACKET_SOCKETS + if (!handlep->sock_packet) { + /* PF_PACKET socket */ + if (handlep->ifindex == -1) { + /* + * We don't support sending on the "any" device. + */ + pcap_strlcpy(handle->errbuf, + "Sending packets isn't supported on the \"any\" device", + PCAP_ERRBUF_SIZE); + return (-1); + } + + if (handlep->cooked) { + /* + * We don't support sending on cooked-mode sockets. + * + * XXX - how do you send on a bound cooked-mode + * socket? + * Is a "sendto()" required there? + */ + pcap_strlcpy(handle->errbuf, + "Sending packets isn't supported in cooked mode", + PCAP_ERRBUF_SIZE); + return (-1); + } + } +#endif + + ret = send(handle->fd, buf, size, 0); + if (ret == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "send"); + return (-1); + } + return (ret); +} + +/* + * Get the statistics for the given packet capture handle. + * Reports the number of dropped packets iff the kernel supports + * the PACKET_STATISTICS "getsockopt()" argument (2.4 and later + * kernels, and 2.2[.x] kernels with Alexey Kuznetzov's turbopacket + * patches); otherwise, that information isn't available, and we lie + * and report 0 as the count of dropped packets. + */ +static int +pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats) +{ + struct pcap_linux *handlep = handle->priv; +#ifdef HAVE_STRUCT_TPACKET_STATS +#ifdef HAVE_TPACKET3 + /* + * For sockets using TPACKET_V1 or TPACKET_V2, the extra + * stuff at the end of a struct tpacket_stats_v3 will not + * be filled in, and we don't look at it so this is OK even + * for those sockets. In addition, the PF_PACKET socket + * code in the kernel only uses the length parameter to + * compute how much data to copy out and to indicate how + * much data was copied out, so it's OK to base it on the + * size of a struct tpacket_stats. + * + * XXX - it's probably OK, in fact, to just use a + * struct tpacket_stats for V3 sockets, as we don't + * care about the tp_freeze_q_cnt stat. + */ + struct tpacket_stats_v3 kstats; +#else /* HAVE_TPACKET3 */ + struct tpacket_stats kstats; +#endif /* HAVE_TPACKET3 */ + socklen_t len = sizeof (struct tpacket_stats); +#endif /* HAVE_STRUCT_TPACKET_STATS */ + + long if_dropped = 0; + + /* + * To fill in ps_ifdrop, we parse /proc/net/dev for the number + */ + if (handle->opt.promisc) + { + if_dropped = handlep->proc_dropped; + handlep->proc_dropped = linux_if_drops(handlep->device); + handlep->stat.ps_ifdrop += (handlep->proc_dropped - if_dropped); + } + +#ifdef HAVE_STRUCT_TPACKET_STATS + /* + * Try to get the packet counts from the kernel. + */ + if (getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, + &kstats, &len) > -1) { + /* + * On systems where the PACKET_STATISTICS "getsockopt()" + * argument is supported on PF_PACKET sockets: + * + * "ps_recv" counts only packets that *passed* the + * filter, not packets that didn't pass the filter. + * This includes packets later dropped because we + * ran out of buffer space. + * + * "ps_drop" counts packets dropped because we ran + * out of buffer space. It doesn't count packets + * dropped by the interface driver. It counts only + * packets that passed the filter. + * + * See above for ps_ifdrop. + * + * Both statistics include packets not yet read from + * the kernel by libpcap, and thus not yet seen by + * the application. + * + * In "linux/net/packet/af_packet.c", at least in the + * 2.4.9 kernel, "tp_packets" is incremented for every + * packet that passes the packet filter *and* is + * successfully queued on the socket; "tp_drops" is + * incremented for every packet dropped because there's + * not enough free space in the socket buffer. + * + * When the statistics are returned for a PACKET_STATISTICS + * "getsockopt()" call, "tp_drops" is added to "tp_packets", + * so that "tp_packets" counts all packets handed to + * the PF_PACKET socket, including packets dropped because + * there wasn't room on the socket buffer - but not + * including packets that didn't pass the filter. + * + * In the BSD BPF, the count of received packets is + * incremented for every packet handed to BPF, regardless + * of whether it passed the filter. + * + * We can't make "pcap_stats()" work the same on both + * platforms, but the best approximation is to return + * "tp_packets" as the count of packets and "tp_drops" + * as the count of drops. + * + * Keep a running total because each call to + * getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, .... + * resets the counters to zero. + */ + handlep->stat.ps_recv += kstats.tp_packets; + handlep->stat.ps_drop += kstats.tp_drops; + *stats = handlep->stat; + return 0; + } + else + { + /* + * If the error was EOPNOTSUPP, fall through, so that + * if you build the library on a system with + * "struct tpacket_stats" and run it on a system + * that doesn't, it works as it does if the library + * is built on a system without "struct tpacket_stats". + */ + if (errno != EOPNOTSUPP) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "pcap_stats"); + return -1; + } + } +#endif + /* + * On systems where the PACKET_STATISTICS "getsockopt()" argument + * is not supported on PF_PACKET sockets: + * + * "ps_recv" counts only packets that *passed* the filter, + * not packets that didn't pass the filter. It does not + * count packets dropped because we ran out of buffer + * space. + * + * "ps_drop" is not supported. + * + * "ps_ifdrop" is supported. It will return the number + * of drops the interface reports in /proc/net/dev, + * if that is available. + * + * "ps_recv" doesn't include packets not yet read from + * the kernel by libpcap. + * + * We maintain the count of packets processed by libpcap in + * "handlep->packets_read", for reasons described in the comment + * at the end of pcap_read_packet(). We have no idea how many + * packets were dropped by the kernel buffers -- but we know + * how many the interface dropped, so we can return that. + */ + + stats->ps_recv = handlep->packets_read; + stats->ps_drop = 0; + stats->ps_ifdrop = handlep->stat.ps_ifdrop; + return 0; +} + +static int +add_linux_if(pcap_if_list_t *devlistp, const char *ifname, int fd, char *errbuf) +{ + const char *p; + char name[512]; /* XXX - pick a size */ + char *q, *saveq; + struct ifreq ifrflags; + + /* + * Get the interface name. + */ + p = ifname; + q = &name[0]; + while (*p != '\0' && isascii(*p) && !isspace(*p)) { + if (*p == ':') { + /* + * This could be the separator between a + * name and an alias number, or it could be + * the separator between a name with no + * alias number and the next field. + * + * If there's a colon after digits, it + * separates the name and the alias number, + * otherwise it separates the name and the + * next field. + */ + saveq = q; + while (isascii(*p) && isdigit(*p)) + *q++ = *p++; + if (*p != ':') { + /* + * That was the next field, + * not the alias number. + */ + q = saveq; + } + break; + } else + *q++ = *p++; + } + *q = '\0'; + + /* + * Get the flags for this interface. + */ + pcap_strlcpy(ifrflags.ifr_name, name, sizeof(ifrflags.ifr_name)); + if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) { + if (errno == ENXIO || errno == ENODEV) + return (0); /* device doesn't actually exist - ignore it */ + pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE, + errno, "SIOCGIFFLAGS: %.*s", + (int)sizeof(ifrflags.ifr_name), + ifrflags.ifr_name); + return (-1); + } + + /* + * Add an entry for this interface, with no addresses, if it's + * not already in the list. + */ + if (find_or_add_if(devlistp, name, ifrflags.ifr_flags, + get_if_flags, errbuf) == NULL) { + /* + * Failure. + */ + return (-1); + } + + return (0); +} + +/* + * Get from "/sys/class/net" all interfaces listed there; if they're + * already in the list of interfaces we have, that won't add another + * instance, but if they're not, that'll add them. + * + * We don't bother getting any addresses for them; it appears you can't + * use SIOCGIFADDR on Linux to get IPv6 addresses for interfaces, and, + * although some other types of addresses can be fetched with SIOCGIFADDR, + * we don't bother with them for now. + * + * We also don't fail if we couldn't open "/sys/class/net"; we just leave + * the list of interfaces as is, and return 0, so that we can try + * scanning /proc/net/dev. + * + * Otherwise, we return 1 if we don't get an error and -1 if we do. + */ +static int +scan_sys_class_net(pcap_if_list_t *devlistp, char *errbuf) +{ + DIR *sys_class_net_d; + int fd; + struct dirent *ent; + char subsystem_path[PATH_MAX+1]; + struct stat statb; + int ret = 1; + + sys_class_net_d = opendir("/sys/class/net"); + if (sys_class_net_d == NULL) { + /* + * Don't fail if it doesn't exist at all. + */ + if (errno == ENOENT) + return (0); + + /* + * Fail if we got some other error. + */ + pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE, + errno, "Can't open /sys/class/net"); + return (-1); + } + + /* + * Create a socket from which to fetch interface information. + */ + fd = socket(PF_UNIX, SOCK_RAW, 0); + if (fd < 0) { + pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE, + errno, "socket"); + (void)closedir(sys_class_net_d); + return (-1); + } + + for (;;) { + errno = 0; + ent = readdir(sys_class_net_d); + if (ent == NULL) { + /* + * Error or EOF; if errno != 0, it's an error. + */ + break; + } + + /* + * Ignore "." and "..". + */ + if (strcmp(ent->d_name, ".") == 0 || + strcmp(ent->d_name, "..") == 0) + continue; + + /* + * Ignore plain files; they do not have subdirectories + * and thus have no attributes. + */ + if (ent->d_type == DT_REG) + continue; + + /* + * Is there an "ifindex" file under that name? + * (We don't care whether it's a directory or + * a symlink; older kernels have directories + * for devices, newer kernels have symlinks to + * directories.) + */ + pcap_snprintf(subsystem_path, sizeof subsystem_path, + "/sys/class/net/%s/ifindex", ent->d_name); + if (lstat(subsystem_path, &statb) != 0) { + /* + * Stat failed. Either there was an error + * other than ENOENT, and we don't know if + * this is an interface, or it's ENOENT, + * and either some part of "/sys/class/net/{if}" + * disappeared, in which case it probably means + * the interface disappeared, or there's no + * "ifindex" file, which means it's not a + * network interface. + */ + continue; + } + + /* + * Attempt to add the interface. + */ + if (add_linux_if(devlistp, &ent->d_name[0], fd, errbuf) == -1) { + /* Fail. */ + ret = -1; + break; + } + } + if (ret != -1) { + /* + * Well, we didn't fail for any other reason; did we + * fail due to an error reading the directory? + */ + if (errno != 0) { + pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE, + errno, "Error reading /sys/class/net"); + ret = -1; + } + } + + (void)close(fd); + (void)closedir(sys_class_net_d); + return (ret); +} + +/* + * Get from "/proc/net/dev" all interfaces listed there; if they're + * already in the list of interfaces we have, that won't add another + * instance, but if they're not, that'll add them. + * + * See comments from scan_sys_class_net(). + */ +static int +scan_proc_net_dev(pcap_if_list_t *devlistp, char *errbuf) +{ + FILE *proc_net_f; + int fd; + char linebuf[512]; + int linenum; + char *p; + int ret = 0; + + proc_net_f = fopen("/proc/net/dev", "r"); + if (proc_net_f == NULL) { + /* + * Don't fail if it doesn't exist at all. + */ + if (errno == ENOENT) + return (0); + + /* + * Fail if we got some other error. + */ + pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE, + errno, "Can't open /proc/net/dev"); + return (-1); + } + + /* + * Create a socket from which to fetch interface information. + */ + fd = socket(PF_UNIX, SOCK_RAW, 0); + if (fd < 0) { + pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE, + errno, "socket"); + (void)fclose(proc_net_f); + return (-1); + } + + for (linenum = 1; + fgets(linebuf, sizeof linebuf, proc_net_f) != NULL; linenum++) { + /* + * Skip the first two lines - they're headers. + */ + if (linenum <= 2) + continue; + + p = &linebuf[0]; + + /* + * Skip leading white space. + */ + while (*p != '\0' && isascii(*p) && isspace(*p)) + p++; + if (*p == '\0' || *p == '\n') + continue; /* blank line */ + + /* + * Attempt to add the interface. + */ + if (add_linux_if(devlistp, p, fd, errbuf) == -1) { + /* Fail. */ + ret = -1; + break; + } + } + if (ret != -1) { + /* + * Well, we didn't fail for any other reason; did we + * fail due to an error reading the file? + */ + if (ferror(proc_net_f)) { + pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE, + errno, "Error reading /proc/net/dev"); + ret = -1; + } + } + + (void)close(fd); + (void)fclose(proc_net_f); + return (ret); +} + +/* + * Description string for the "any" device. + */ +static const char any_descr[] = "Pseudo-device that captures on all interfaces"; + +/* + * A SOCK_PACKET or PF_PACKET socket can be bound to any network interface. + */ +static int +can_be_bound(const char *name _U_) +{ + return (1); +} + +/* + * Get additional flags for a device, using SIOCGIFMEDIA. + */ +static int +get_if_flags(const char *name, bpf_u_int32 *flags, char *errbuf) +{ + int sock; + FILE *fh; + unsigned int arptype; + struct ifreq ifr; + struct ethtool_value info; + + if (*flags & PCAP_IF_LOOPBACK) { + /* + * Loopback devices aren't wireless, and "connected"/ + * "disconnected" doesn't apply to them. + */ + *flags |= PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE; + return 0; + } + + sock = socket(AF_INET, SOCK_DGRAM, 0); + if (sock == -1) { + pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE, errno, + "Can't create socket to get ethtool information for %s", + name); + return -1; + } + + /* + * OK, what type of network is this? + * In particular, is it wired or wireless? + */ + if (is_wifi(sock, name)) { + /* + * Wi-Fi, hence wireless. + */ + *flags |= PCAP_IF_WIRELESS; + } else { + /* + * OK, what does /sys/class/net/{if}/type contain? + * (We don't use that for Wi-Fi, as it'll report + * "Ethernet", i.e. ARPHRD_ETHER, for non-monitor- + * mode devices.) + */ + char *pathstr; + + if (asprintf(&pathstr, "/sys/class/net/%s/type", name) == -1) { + pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE, + "%s: Can't generate path name string for /sys/class/net device", + name); + close(sock); + return -1; + } + fh = fopen(pathstr, "r"); + if (fh != NULL) { + if (fscanf(fh, "%u", &arptype) == 1) { + /* + * OK, we got an ARPHRD_ type; what is it? + */ + switch (arptype) { + +#ifdef ARPHRD_LOOPBACK + case ARPHRD_LOOPBACK: + /* + * These are types to which + * "connected" and "disconnected" + * don't apply, so don't bother + * asking about it. + * + * XXX - add other types? + */ + close(sock); + fclose(fh); + free(pathstr); + return 0; +#endif + + case ARPHRD_IRDA: + case ARPHRD_IEEE80211: + case ARPHRD_IEEE80211_PRISM: + case ARPHRD_IEEE80211_RADIOTAP: +#ifdef ARPHRD_IEEE802154 + case ARPHRD_IEEE802154: +#endif +#ifdef ARPHRD_IEEE802154_MONITOR + case ARPHRD_IEEE802154_MONITOR: +#endif +#ifdef ARPHRD_6LOWPAN + case ARPHRD_6LOWPAN: +#endif + /* + * Various wireless types. + */ + *flags |= PCAP_IF_WIRELESS; + break; + } + } + fclose(fh); + free(pathstr); + } + } + +#ifdef ETHTOOL_GLINK + memset(&ifr, 0, sizeof(ifr)); + pcap_strlcpy(ifr.ifr_name, name, sizeof(ifr.ifr_name)); + info.cmd = ETHTOOL_GLINK; + ifr.ifr_data = (caddr_t)&info; + if (ioctl(sock, SIOCETHTOOL, &ifr) == -1) { + int save_errno = errno; + + switch (save_errno) { + + case EOPNOTSUPP: + case EINVAL: + /* + * OK, this OS version or driver doesn't support + * asking for this information. + * XXX - distinguish between "this doesn't + * support ethtool at all because it's not + * that type of device" vs. "this doesn't + * support ethtool even though it's that + * type of device", and return "unknown". + */ + *flags |= PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE; + close(sock); + return 0; + + case ENODEV: + /* + * OK, no such device. + * The user will find that out when they try to + * activate the device; just say "OK" and + * don't set anything. + */ + close(sock); + return 0; + + default: + /* + * Other error. + */ + pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE, + save_errno, + "%s: SIOCETHTOOL(ETHTOOL_GLINK) ioctl failed", + name); + close(sock); + return -1; + } + } + + /* + * Is it connected? + */ + if (info.data) { + /* + * It's connected. + */ + *flags |= PCAP_IF_CONNECTION_STATUS_CONNECTED; + } else { + /* + * It's disconnected. + */ + *flags |= PCAP_IF_CONNECTION_STATUS_DISCONNECTED; + } +#endif + + close(sock); + return 0; +} + +int +pcap_platform_finddevs(pcap_if_list_t *devlistp, char *errbuf) +{ + int ret; + + /* + * Get the list of regular interfaces first. + */ + if (pcap_findalldevs_interfaces(devlistp, errbuf, can_be_bound, + get_if_flags) == -1) + return (-1); /* failure */ + + /* + * Read "/sys/class/net", and add to the list of interfaces all + * interfaces listed there that we don't already have, because, + * on Linux, SIOCGIFCONF reports only interfaces with IPv4 addresses, + * and even getifaddrs() won't return information about + * interfaces with no addresses, so you need to read "/sys/class/net" + * to get the names of the rest of the interfaces. + */ + ret = scan_sys_class_net(devlistp, errbuf); + if (ret == -1) + return (-1); /* failed */ + if (ret == 0) { + /* + * No /sys/class/net; try reading /proc/net/dev instead. + */ + if (scan_proc_net_dev(devlistp, errbuf) == -1) + return (-1); + } + + /* + * Add the "any" device. + * As it refers to all network devices, not to any particular + * network device, the notion of "connected" vs. "disconnected" + * doesn't apply. + */ + if (add_dev(devlistp, "any", + PCAP_IF_UP|PCAP_IF_RUNNING|PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, + any_descr, errbuf) == NULL) + return (-1); + + return (0); +} + +/* + * Attach the given BPF code to the packet capture device. + */ +static int +pcap_setfilter_linux_common(pcap_t *handle, struct bpf_program *filter, + int is_mmapped) +{ + struct pcap_linux *handlep; +#ifdef SO_ATTACH_FILTER + struct sock_fprog fcode; + int can_filter_in_kernel; + int err = 0; +#endif + + if (!handle) + return -1; + if (!filter) { + pcap_strlcpy(handle->errbuf, "setfilter: No filter specified", + PCAP_ERRBUF_SIZE); + return -1; + } + + handlep = handle->priv; + + /* Make our private copy of the filter */ + + if (install_bpf_program(handle, filter) < 0) + /* install_bpf_program() filled in errbuf */ + return -1; + + /* + * Run user level packet filter by default. Will be overriden if + * installing a kernel filter succeeds. + */ + handlep->filter_in_userland = 1; + + /* Install kernel level filter if possible */ + +#ifdef SO_ATTACH_FILTER +#ifdef USHRT_MAX + if (handle->fcode.bf_len > USHRT_MAX) { + /* + * fcode.len is an unsigned short for current kernel. + * I have yet to see BPF-Code with that much + * instructions but still it is possible. So for the + * sake of correctness I added this check. + */ + fprintf(stderr, "Warning: Filter too complex for kernel\n"); + fcode.len = 0; + fcode.filter = NULL; + can_filter_in_kernel = 0; + } else +#endif /* USHRT_MAX */ + { + /* + * Oh joy, the Linux kernel uses struct sock_fprog instead + * of struct bpf_program and of course the length field is + * of different size. Pointed out by Sebastian + * + * Oh, and we also need to fix it up so that all "ret" + * instructions with non-zero operands have MAXIMUM_SNAPLEN + * as the operand if we're not capturing in memory-mapped + * mode, and so that, if we're in cooked mode, all memory- + * reference instructions use special magic offsets in + * references to the link-layer header and assume that the + * link-layer payload begins at 0; "fix_program()" will do + * that. + */ + switch (fix_program(handle, &fcode, is_mmapped)) { + + case -1: + default: + /* + * Fatal error; just quit. + * (The "default" case shouldn't happen; we + * return -1 for that reason.) + */ + return -1; + + case 0: + /* + * The program performed checks that we can't make + * work in the kernel. + */ + can_filter_in_kernel = 0; + break; + + case 1: + /* + * We have a filter that'll work in the kernel. + */ + can_filter_in_kernel = 1; + break; + } + } + + /* + * NOTE: at this point, we've set both the "len" and "filter" + * fields of "fcode". As of the 2.6.32.4 kernel, at least, + * those are the only members of the "sock_fprog" structure, + * so we initialize every member of that structure. + * + * If there is anything in "fcode" that is not initialized, + * it is either a field added in a later kernel, or it's + * padding. + * + * If a new field is added, this code needs to be updated + * to set it correctly. + * + * If there are no other fields, then: + * + * if the Linux kernel looks at the padding, it's + * buggy; + * + * if the Linux kernel doesn't look at the padding, + * then if some tool complains that we're passing + * uninitialized data to the kernel, then the tool + * is buggy and needs to understand that it's just + * padding. + */ + if (can_filter_in_kernel) { + if ((err = set_kernel_filter(handle, &fcode)) == 0) + { + /* + * Installation succeded - using kernel filter, + * so userland filtering not needed. + */ + handlep->filter_in_userland = 0; + } + else if (err == -1) /* Non-fatal error */ + { + /* + * Print a warning if we weren't able to install + * the filter for a reason other than "this kernel + * isn't configured to support socket filters. + */ + if (errno != ENOPROTOOPT && errno != EOPNOTSUPP) { + fprintf(stderr, + "Warning: Kernel filter failed: %s\n", + pcap_strerror(errno)); + } + } + } + + /* + * If we're not using the kernel filter, get rid of any kernel + * filter that might've been there before, e.g. because the + * previous filter could work in the kernel, or because some other + * code attached a filter to the socket by some means other than + * calling "pcap_setfilter()". Otherwise, the kernel filter may + * filter out packets that would pass the new userland filter. + */ + if (handlep->filter_in_userland) { + if (reset_kernel_filter(handle) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "can't remove kernel filter"); + err = -2; /* fatal error */ + } + } + + /* + * Free up the copy of the filter that was made by "fix_program()". + */ + if (fcode.filter != NULL) + free(fcode.filter); + + if (err == -2) + /* Fatal error */ + return -1; +#endif /* SO_ATTACH_FILTER */ + + return 0; +} + +static int +pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter) +{ + return pcap_setfilter_linux_common(handle, filter, 0); +} + + +/* + * Set direction flag: Which packets do we accept on a forwarding + * single device? IN, OUT or both? + */ +static int +pcap_setdirection_linux(pcap_t *handle, pcap_direction_t d) +{ +#ifdef HAVE_PF_PACKET_SOCKETS + struct pcap_linux *handlep = handle->priv; + + if (!handlep->sock_packet) { + handle->direction = d; + return 0; + } +#endif + /* + * We're not using PF_PACKET sockets, so we can't determine + * the direction of the packet. + */ + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "Setting direction is not supported on SOCK_PACKET sockets"); + return -1; +} + +static int +is_wifi(int sock_fd +#ifndef IW_MODE_MONITOR +_U_ +#endif +, const char *device) +{ + char *pathstr; + struct stat statb; +#ifdef IW_MODE_MONITOR + char errbuf[PCAP_ERRBUF_SIZE]; +#endif + + /* + * See if there's a sysfs wireless directory for it. + * If so, it's a wireless interface. + */ + if (asprintf(&pathstr, "/sys/class/net/%s/wireless", device) == -1) { + /* + * Just give up here. + */ + return 0; + } + if (stat(pathstr, &statb) == 0) { + free(pathstr); + return 1; + } + free(pathstr); + +#ifdef IW_MODE_MONITOR + /* + * OK, maybe it's not wireless, or maybe this kernel doesn't + * support sysfs. Try the wireless extensions. + */ + if (has_wext(sock_fd, device, errbuf) == 1) { + /* + * It supports the wireless extensions, so it's a Wi-Fi + * device. + */ + return 1; + } +#endif + return 0; +} + +/* + * Linux uses the ARP hardware type to identify the type of an + * interface. pcap uses the DLT_xxx constants for this. This + * function takes a pointer to a "pcap_t", and an ARPHRD_xxx + * constant, as arguments, and sets "handle->linktype" to the + * appropriate DLT_XXX constant and sets "handle->offset" to + * the appropriate value (to make "handle->offset" plus link-layer + * header length be a multiple of 4, so that the link-layer payload + * will be aligned on a 4-byte boundary when capturing packets). + * (If the offset isn't set here, it'll be 0; add code as appropriate + * for cases where it shouldn't be 0.) + * + * If "cooked_ok" is non-zero, we can use DLT_LINUX_SLL and capture + * in cooked mode; otherwise, we can't use cooked mode, so we have + * to pick some type that works in raw mode, or fail. + * + * Sets the link type to -1 if unable to map the type. + */ +static void map_arphrd_to_dlt(pcap_t *handle, int sock_fd, int arptype, + const char *device, int cooked_ok) +{ + static const char cdma_rmnet[] = "cdma_rmnet"; + + switch (arptype) { + + case ARPHRD_ETHER: + /* + * For various annoying reasons having to do with DHCP + * software, some versions of Android give the mobile- + * phone-network interface an ARPHRD_ value of + * ARPHRD_ETHER, even though the packets supplied by + * that interface have no link-layer header, and begin + * with an IP header, so that the ARPHRD_ value should + * be ARPHRD_NONE. + * + * Detect those devices by checking the device name, and + * use DLT_RAW for them. + */ + if (strncmp(device, cdma_rmnet, sizeof cdma_rmnet - 1) == 0) { + handle->linktype = DLT_RAW; + return; + } + + /* + * Is this a real Ethernet device? If so, give it a + * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so + * that an application can let you choose it, in case you're + * capturing DOCSIS traffic that a Cisco Cable Modem + * Termination System is putting out onto an Ethernet (it + * doesn't put an Ethernet header onto the wire, it puts raw + * DOCSIS frames out on the wire inside the low-level + * Ethernet framing). + * + * XXX - are there any other sorts of "fake Ethernet" that + * have ARPHRD_ETHER but that shouldn't offer DLT_DOCSIS as + * a Cisco CMTS won't put traffic onto it or get traffic + * bridged onto it? ISDN is handled in "activate_new()", + * as we fall back on cooked mode there, and we use + * is_wifi() to check for 802.11 devices; are there any + * others? + */ + if (!is_wifi(sock_fd, device)) { + /* + * It's not a Wi-Fi device; offer DOCSIS. + */ + handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2); + /* + * If that fails, just leave the list empty. + */ + if (handle->dlt_list != NULL) { + handle->dlt_list[0] = DLT_EN10MB; + handle->dlt_list[1] = DLT_DOCSIS; + handle->dlt_count = 2; + } + } + /* FALLTHROUGH */ + + case ARPHRD_METRICOM: + case ARPHRD_LOOPBACK: + handle->linktype = DLT_EN10MB; + handle->offset = 2; + break; + + case ARPHRD_EETHER: + handle->linktype = DLT_EN3MB; + break; + + case ARPHRD_AX25: + handle->linktype = DLT_AX25_KISS; + break; + + case ARPHRD_PRONET: + handle->linktype = DLT_PRONET; + break; + + case ARPHRD_CHAOS: + handle->linktype = DLT_CHAOS; + break; +#ifndef ARPHRD_CAN +#define ARPHRD_CAN 280 +#endif + case ARPHRD_CAN: + /* + * Map this to DLT_LINUX_SLL; that way, CAN frames will + * have ETH_P_CAN/LINUX_SLL_P_CAN as the protocol and + * CAN FD frames will have ETH_P_CANFD/LINUX_SLL_P_CANFD + * as the protocol, so they can be distinguished by the + * protocol in the SLL header. + */ + handle->linktype = DLT_LINUX_SLL; + break; + +#ifndef ARPHRD_IEEE802_TR +#define ARPHRD_IEEE802_TR 800 /* From Linux 2.4 */ +#endif + case ARPHRD_IEEE802_TR: + case ARPHRD_IEEE802: + handle->linktype = DLT_IEEE802; + handle->offset = 2; + break; + + case ARPHRD_ARCNET: + handle->linktype = DLT_ARCNET_LINUX; + break; + +#ifndef ARPHRD_FDDI /* From Linux 2.2.13 */ +#define ARPHRD_FDDI 774 +#endif + case ARPHRD_FDDI: + handle->linktype = DLT_FDDI; + handle->offset = 3; + break; + +#ifndef ARPHRD_ATM /* FIXME: How to #include this? */ +#define ARPHRD_ATM 19 +#endif + case ARPHRD_ATM: + /* + * The Classical IP implementation in ATM for Linux + * supports both what RFC 1483 calls "LLC Encapsulation", + * in which each packet has an LLC header, possibly + * with a SNAP header as well, prepended to it, and + * what RFC 1483 calls "VC Based Multiplexing", in which + * different virtual circuits carry different network + * layer protocols, and no header is prepended to packets. + * + * They both have an ARPHRD_ type of ARPHRD_ATM, so + * you can't use the ARPHRD_ type to find out whether + * captured packets will have an LLC header, and, + * while there's a socket ioctl to *set* the encapsulation + * type, there's no ioctl to *get* the encapsulation type. + * + * This means that + * + * programs that dissect Linux Classical IP frames + * would have to check for an LLC header and, + * depending on whether they see one or not, dissect + * the frame as LLC-encapsulated or as raw IP (I + * don't know whether there's any traffic other than + * IP that would show up on the socket, or whether + * there's any support for IPv6 in the Linux + * Classical IP code); + * + * filter expressions would have to compile into + * code that checks for an LLC header and does + * the right thing. + * + * Both of those are a nuisance - and, at least on systems + * that support PF_PACKET sockets, we don't have to put + * up with those nuisances; instead, we can just capture + * in cooked mode. That's what we'll do, if we can. + * Otherwise, we'll just fail. + */ + if (cooked_ok) + handle->linktype = DLT_LINUX_SLL; + else + handle->linktype = -1; + break; + +#ifndef ARPHRD_IEEE80211 /* From Linux 2.4.6 */ +#define ARPHRD_IEEE80211 801 +#endif + case ARPHRD_IEEE80211: + handle->linktype = DLT_IEEE802_11; + break; + +#ifndef ARPHRD_IEEE80211_PRISM /* From Linux 2.4.18 */ +#define ARPHRD_IEEE80211_PRISM 802 +#endif + case ARPHRD_IEEE80211_PRISM: + handle->linktype = DLT_PRISM_HEADER; + break; + +#ifndef ARPHRD_IEEE80211_RADIOTAP /* new */ +#define ARPHRD_IEEE80211_RADIOTAP 803 +#endif + case ARPHRD_IEEE80211_RADIOTAP: + handle->linktype = DLT_IEEE802_11_RADIO; + break; + + case ARPHRD_PPP: + /* + * Some PPP code in the kernel supplies no link-layer + * header whatsoever to PF_PACKET sockets; other PPP + * code supplies PPP link-layer headers ("syncppp.c"); + * some PPP code might supply random link-layer + * headers (PPP over ISDN - there's code in Ethereal, + * for example, to cope with PPP-over-ISDN captures + * with which the Ethereal developers have had to cope, + * heuristically trying to determine which of the + * oddball link-layer headers particular packets have). + * + * As such, we just punt, and run all PPP interfaces + * in cooked mode, if we can; otherwise, we just treat + * it as DLT_RAW, for now - if somebody needs to capture, + * on a 2.0[.x] kernel, on PPP devices that supply a + * link-layer header, they'll have to add code here to + * map to the appropriate DLT_ type (possibly adding a + * new DLT_ type, if necessary). + */ + if (cooked_ok) + handle->linktype = DLT_LINUX_SLL; + else { + /* + * XXX - handle ISDN types here? We can't fall + * back on cooked sockets, so we'd have to + * figure out from the device name what type of + * link-layer encapsulation it's using, and map + * that to an appropriate DLT_ value, meaning + * we'd map "isdnN" devices to DLT_RAW (they + * supply raw IP packets with no link-layer + * header) and "isdY" devices to a new DLT_I4L_IP + * type that has only an Ethernet packet type as + * a link-layer header. + * + * But sometimes we seem to get random crap + * in the link-layer header when capturing on + * ISDN devices.... + */ + handle->linktype = DLT_RAW; + } + break; + +#ifndef ARPHRD_CISCO +#define ARPHRD_CISCO 513 /* previously ARPHRD_HDLC */ +#endif + case ARPHRD_CISCO: + handle->linktype = DLT_C_HDLC; + break; + + /* Not sure if this is correct for all tunnels, but it + * works for CIPE */ + case ARPHRD_TUNNEL: +#ifndef ARPHRD_SIT +#define ARPHRD_SIT 776 /* From Linux 2.2.13 */ +#endif + case ARPHRD_SIT: + case ARPHRD_CSLIP: + case ARPHRD_SLIP6: + case ARPHRD_CSLIP6: + case ARPHRD_ADAPT: + case ARPHRD_SLIP: +#ifndef ARPHRD_RAWHDLC +#define ARPHRD_RAWHDLC 518 +#endif + case ARPHRD_RAWHDLC: +#ifndef ARPHRD_DLCI +#define ARPHRD_DLCI 15 +#endif + case ARPHRD_DLCI: + /* + * XXX - should some of those be mapped to DLT_LINUX_SLL + * instead? Should we just map all of them to DLT_LINUX_SLL? + */ + handle->linktype = DLT_RAW; + break; + +#ifndef ARPHRD_FRAD +#define ARPHRD_FRAD 770 +#endif + case ARPHRD_FRAD: + handle->linktype = DLT_FRELAY; + break; + + case ARPHRD_LOCALTLK: + handle->linktype = DLT_LTALK; + break; + + case 18: + /* + * RFC 4338 defines an encapsulation for IP and ARP + * packets that's compatible with the RFC 2625 + * encapsulation, but that uses a different ARP + * hardware type and hardware addresses. That + * ARP hardware type is 18; Linux doesn't define + * any ARPHRD_ value as 18, but if it ever officially + * supports RFC 4338-style IP-over-FC, it should define + * one. + * + * For now, we map it to DLT_IP_OVER_FC, in the hopes + * that this will encourage its use in the future, + * should Linux ever officially support RFC 4338-style + * IP-over-FC. + */ + handle->linktype = DLT_IP_OVER_FC; + break; + +#ifndef ARPHRD_FCPP +#define ARPHRD_FCPP 784 +#endif + case ARPHRD_FCPP: +#ifndef ARPHRD_FCAL +#define ARPHRD_FCAL 785 +#endif + case ARPHRD_FCAL: +#ifndef ARPHRD_FCPL +#define ARPHRD_FCPL 786 +#endif + case ARPHRD_FCPL: +#ifndef ARPHRD_FCFABRIC +#define ARPHRD_FCFABRIC 787 +#endif + case ARPHRD_FCFABRIC: + /* + * Back in 2002, Donald Lee at Cray wanted a DLT_ for + * IP-over-FC: + * + * http://www.mail-archive.com/tcpdump-workers@sandelman.ottawa.on.ca/msg01043.html + * + * and one was assigned. + * + * In a later private discussion (spun off from a message + * on the ethereal-users list) on how to get that DLT_ + * value in libpcap on Linux, I ended up deciding that + * the best thing to do would be to have him tweak the + * driver to set the ARPHRD_ value to some ARPHRD_FCxx + * type, and map all those types to DLT_IP_OVER_FC: + * + * I've checked into the libpcap and tcpdump CVS tree + * support for DLT_IP_OVER_FC. In order to use that, + * you'd have to modify your modified driver to return + * one of the ARPHRD_FCxxx types, in "fcLINUXfcp.c" - + * change it to set "dev->type" to ARPHRD_FCFABRIC, for + * example (the exact value doesn't matter, it can be + * any of ARPHRD_FCPP, ARPHRD_FCAL, ARPHRD_FCPL, or + * ARPHRD_FCFABRIC). + * + * 11 years later, Christian Svensson wanted to map + * various ARPHRD_ values to DLT_FC_2 and + * DLT_FC_2_WITH_FRAME_DELIMS for raw Fibre Channel + * frames: + * + * https://github.com/mcr/libpcap/pull/29 + * + * There doesn't seem to be any network drivers that uses + * any of the ARPHRD_FC* values for IP-over-FC, and + * it's not exactly clear what the "Dummy types for non + * ARP hardware" are supposed to mean (link-layer + * header type? Physical network type?), so it's + * not exactly clear why the ARPHRD_FC* types exist + * in the first place. + * + * For now, we map them to DLT_FC_2, and provide an + * option of DLT_FC_2_WITH_FRAME_DELIMS, as well as + * DLT_IP_OVER_FC just in case there's some old + * driver out there that uses one of those types for + * IP-over-FC on which somebody wants to capture + * packets. + */ + handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 3); + /* + * If that fails, just leave the list empty. + */ + if (handle->dlt_list != NULL) { + handle->dlt_list[0] = DLT_FC_2; + handle->dlt_list[1] = DLT_FC_2_WITH_FRAME_DELIMS; + handle->dlt_list[2] = DLT_IP_OVER_FC; + handle->dlt_count = 3; + } + handle->linktype = DLT_FC_2; + break; + +#ifndef ARPHRD_IRDA +#define ARPHRD_IRDA 783 +#endif + case ARPHRD_IRDA: + /* Don't expect IP packet out of this interfaces... */ + handle->linktype = DLT_LINUX_IRDA; + /* We need to save packet direction for IrDA decoding, + * so let's use "Linux-cooked" mode. Jean II + * + * XXX - this is handled in activate_new(). */ + /* handlep->cooked = 1; */ + break; + + /* ARPHRD_LAPD is unofficial and randomly allocated, if reallocation + * is needed, please report it to <daniele@orlandi.com> */ +#ifndef ARPHRD_LAPD +#define ARPHRD_LAPD 8445 +#endif + case ARPHRD_LAPD: + /* Don't expect IP packet out of this interfaces... */ + handle->linktype = DLT_LINUX_LAPD; + break; + +#ifndef ARPHRD_NONE +#define ARPHRD_NONE 0xFFFE +#endif + case ARPHRD_NONE: + /* + * No link-layer header; packets are just IP + * packets, so use DLT_RAW. + */ + handle->linktype = DLT_RAW; + break; + +#ifndef ARPHRD_IEEE802154 +#define ARPHRD_IEEE802154 804 +#endif + case ARPHRD_IEEE802154: + handle->linktype = DLT_IEEE802_15_4_NOFCS; + break; + +#ifndef ARPHRD_NETLINK +#define ARPHRD_NETLINK 824 +#endif + case ARPHRD_NETLINK: + handle->linktype = DLT_NETLINK; + /* + * We need to use cooked mode, so that in sll_protocol we + * pick up the netlink protocol type such as NETLINK_ROUTE, + * NETLINK_GENERIC, NETLINK_FIB_LOOKUP, etc. + * + * XXX - this is handled in activate_new(). + */ + /* handlep->cooked = 1; */ + break; + +#ifndef ARPHRD_VSOCKMON +#define ARPHRD_VSOCKMON 826 +#endif + case ARPHRD_VSOCKMON: + handle->linktype = DLT_VSOCK; + break; + + default: + handle->linktype = -1; + break; + } +} + +/* ===== Functions to interface to the newer kernels ================== */ + +#ifdef PACKET_RESERVE +static void +set_dlt_list_cooked(pcap_t *handle, int sock_fd) +{ + socklen_t len; + unsigned int tp_reserve; + + /* + * If we can't do PACKET_RESERVE, we can't reserve extra space + * for a DLL_LINUX_SLL2 header, so we can't support DLT_LINUX_SLL2. + */ + len = sizeof(tp_reserve); + if (getsockopt(sock_fd, SOL_PACKET, PACKET_RESERVE, &tp_reserve, + &len) == 0) { + /* + * Yes, we can do DLL_LINUX_SLL2. + */ + handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2); + /* + * If that fails, just leave the list empty. + */ + if (handle->dlt_list != NULL) { + handle->dlt_list[0] = DLT_LINUX_SLL; + handle->dlt_list[1] = DLT_LINUX_SLL2; + handle->dlt_count = 2; + } + } +} +#else +/* + * The build environment doesn't define PACKET_RESERVE, so we can't reserve + * extra space for a DLL_LINUX_SLL2 header, so we can't support DLT_LINUX_SLL2. + */ +static void +set_dlt_list_cooked(pcap_t *handle _U_, int sock_fd _U_) +{ +} +#endif + +/* + * Try to open a packet socket using the new kernel PF_PACKET interface. + * Returns 1 on success, 0 on an error that means the new interface isn't + * present (so the old SOCK_PACKET interface should be tried), and a + * PCAP_ERROR_ value on an error that means that the old mechanism won't + * work either (so it shouldn't be tried). + */ +static int +activate_new(pcap_t *handle) +{ +#ifdef HAVE_PF_PACKET_SOCKETS + struct pcap_linux *handlep = handle->priv; + const char *device = handle->opt.device; + int is_any_device = (strcmp(device, "any") == 0); + int protocol = pcap_protocol(handle); + int sock_fd = -1, arptype, ret; +#ifdef HAVE_PACKET_AUXDATA + int val; +#endif + int err = 0; + struct packet_mreq mr; +#if defined(SO_BPF_EXTENSIONS) && defined(SKF_AD_VLAN_TAG_PRESENT) + int bpf_extensions; + socklen_t len = sizeof(bpf_extensions); +#endif + + /* + * Open a socket with protocol family packet. If the + * "any" device was specified, we open a SOCK_DGRAM + * socket for the cooked interface, otherwise we first + * try a SOCK_RAW socket for the raw interface. + */ + sock_fd = is_any_device ? + socket(PF_PACKET, SOCK_DGRAM, protocol) : + socket(PF_PACKET, SOCK_RAW, protocol); + + if (sock_fd == -1) { + if (errno == EINVAL || errno == EAFNOSUPPORT) { + /* + * We don't support PF_PACKET/SOCK_whatever + * sockets; try the old mechanism. + */ + return 0; + } + if (errno == EPERM || errno == EACCES) { + /* + * You don't have permission to open the + * socket. + */ + ret = PCAP_ERROR_PERM_DENIED; + } else { + /* + * Other error. + */ + ret = PCAP_ERROR; + } + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "socket"); + return ret; + } + + /* It seems the kernel supports the new interface. */ + handlep->sock_packet = 0; + + /* + * Get the interface index of the loopback device. + * If the attempt fails, don't fail, just set the + * "handlep->lo_ifindex" to -1. + * + * XXX - can there be more than one device that loops + * packets back, i.e. devices other than "lo"? If so, + * we'd need to find them all, and have an array of + * indices for them, and check all of them in + * "pcap_read_packet()". + */ + handlep->lo_ifindex = iface_get_id(sock_fd, "lo", handle->errbuf); + + /* + * Default value for offset to align link-layer payload + * on a 4-byte boundary. + */ + handle->offset = 0; + + /* + * What kind of frames do we have to deal with? Fall back + * to cooked mode if we have an unknown interface type + * or a type we know doesn't work well in raw mode. + */ + if (!is_any_device) { + /* Assume for now we don't need cooked mode. */ + handlep->cooked = 0; + + if (handle->opt.rfmon) { + /* + * We were asked to turn on monitor mode. + * Do so before we get the link-layer type, + * because entering monitor mode could change + * the link-layer type. + */ + err = enter_rfmon_mode(handle, sock_fd, device); + if (err < 0) { + /* Hard failure */ + close(sock_fd); + return err; + } + if (err == 0) { + /* + * Nothing worked for turning monitor mode + * on. + */ + close(sock_fd); + return PCAP_ERROR_RFMON_NOTSUP; + } + + /* + * Either monitor mode has been turned on for + * the device, or we've been given a different + * device to open for monitor mode. If we've + * been given a different device, use it. + */ + if (handlep->mondevice != NULL) + device = handlep->mondevice; + } + arptype = iface_get_arptype(sock_fd, device, handle->errbuf); + if (arptype < 0) { + close(sock_fd); + return arptype; + } + map_arphrd_to_dlt(handle, sock_fd, arptype, device, 1); + if (handle->linktype == -1 || + handle->linktype == DLT_LINUX_SLL || + handle->linktype == DLT_LINUX_IRDA || + handle->linktype == DLT_LINUX_LAPD || + handle->linktype == DLT_NETLINK || + (handle->linktype == DLT_EN10MB && + (strncmp("isdn", device, 4) == 0 || + strncmp("isdY", device, 4) == 0))) { + /* + * Unknown interface type (-1), or a + * device we explicitly chose to run + * in cooked mode (e.g., PPP devices), + * or an ISDN device (whose link-layer + * type we can only determine by using + * APIs that may be different on different + * kernels) - reopen in cooked mode. + */ + if (close(sock_fd) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "close"); + return PCAP_ERROR; + } + sock_fd = socket(PF_PACKET, SOCK_DGRAM, protocol); + if (sock_fd == -1) { + if (errno == EPERM || errno == EACCES) { + /* + * You don't have permission to + * open the socket. + */ + ret = PCAP_ERROR_PERM_DENIED; + } else { + /* + * Other error. + */ + ret = PCAP_ERROR; + } + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "socket"); + return ret; + } + handlep->cooked = 1; + + /* + * Get rid of any link-layer type list + * we allocated - this only supports cooked + * capture. + */ + if (handle->dlt_list != NULL) { + free(handle->dlt_list); + handle->dlt_list = NULL; + handle->dlt_count = 0; + set_dlt_list_cooked(handle, sock_fd); + } + + if (handle->linktype == -1) { + /* + * Warn that we're falling back on + * cooked mode; we may want to + * update "map_arphrd_to_dlt()" + * to handle the new type. + */ + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "arptype %d not " + "supported by libpcap - " + "falling back to cooked " + "socket", + arptype); + } + + /* + * IrDA capture is not a real "cooked" capture, + * it's IrLAP frames, not IP packets. The + * same applies to LAPD capture. + */ + if (handle->linktype != DLT_LINUX_IRDA && + handle->linktype != DLT_LINUX_LAPD && + handle->linktype != DLT_NETLINK) + handle->linktype = DLT_LINUX_SLL; + } + + handlep->ifindex = iface_get_id(sock_fd, device, + handle->errbuf); + if (handlep->ifindex == -1) { + close(sock_fd); + return PCAP_ERROR; + } + + if ((err = iface_bind(sock_fd, handlep->ifindex, + handle->errbuf, protocol)) != 1) { + close(sock_fd); + if (err < 0) + return err; + else + return 0; /* try old mechanism */ + } + } else { + /* + * The "any" device. + */ + if (handle->opt.rfmon) { + /* + * It doesn't support monitor mode. + */ + close(sock_fd); + return PCAP_ERROR_RFMON_NOTSUP; + } + + /* + * It uses cooked mode. + */ + handlep->cooked = 1; + handle->linktype = DLT_LINUX_SLL; + handle->dlt_list = NULL; + handle->dlt_count = 0; + set_dlt_list_cooked(handle, sock_fd); + + /* + * We're not bound to a device. + * For now, we're using this as an indication + * that we can't transmit; stop doing that only + * if we figure out how to transmit in cooked + * mode. + */ + handlep->ifindex = -1; + } + + /* + * Select promiscuous mode on if "promisc" is set. + * + * Do not turn allmulti mode on if we don't select + * promiscuous mode - on some devices (e.g., Orinoco + * wireless interfaces), allmulti mode isn't supported + * and the driver implements it by turning promiscuous + * mode on, and that screws up the operation of the + * card as a normal networking interface, and on no + * other platform I know of does starting a non- + * promiscuous capture affect which multicast packets + * are received by the interface. + */ + + /* + * Hmm, how can we set promiscuous mode on all interfaces? + * I am not sure if that is possible at all. For now, we + * silently ignore attempts to turn promiscuous mode on + * for the "any" device (so you don't have to explicitly + * disable it in programs such as tcpdump). + */ + + if (!is_any_device && handle->opt.promisc) { + memset(&mr, 0, sizeof(mr)); + mr.mr_ifindex = handlep->ifindex; + mr.mr_type = PACKET_MR_PROMISC; + if (setsockopt(sock_fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, + &mr, sizeof(mr)) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "setsockopt (PACKET_ADD_MEMBERSHIP)"); + close(sock_fd); + return PCAP_ERROR; + } + } + + /* Enable auxillary data if supported and reserve room for + * reconstructing VLAN headers. */ +#ifdef HAVE_PACKET_AUXDATA + val = 1; + if (setsockopt(sock_fd, SOL_PACKET, PACKET_AUXDATA, &val, + sizeof(val)) == -1 && errno != ENOPROTOOPT) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "setsockopt (PACKET_AUXDATA)"); + close(sock_fd); + return PCAP_ERROR; + } + handle->offset += VLAN_TAG_LEN; +#endif /* HAVE_PACKET_AUXDATA */ + + /* + * This is a 2.2[.x] or later kernel (we know that + * because we're not using a SOCK_PACKET socket - + * PF_PACKET is supported only in 2.2 and later + * kernels). + * + * We can safely pass "recvfrom()" a byte count + * based on the snapshot length. + * + * If we're in cooked mode, make the snapshot length + * large enough to hold a "cooked mode" header plus + * 1 byte of packet data (so we don't pass a byte + * count of 0 to "recvfrom()"). + * XXX - we don't know whether this will be DLT_LINUX_SLL + * or DLT_LINUX_SLL2, so make sure it's big enough for + * a DLT_LINUX_SLL2 "cooked mode" header; a snapshot length + * that small is silly anyway. + */ + if (handlep->cooked) { + if (handle->snapshot < SLL2_HDR_LEN + 1) + handle->snapshot = SLL2_HDR_LEN + 1; + } + handle->bufsize = handle->snapshot; + + /* + * Set the offset at which to insert VLAN tags. + * That should be the offset of the type field. + */ + switch (handle->linktype) { + + case DLT_EN10MB: + /* + * The type field is after the destination and source + * MAC address. + */ + handlep->vlan_offset = 2 * ETH_ALEN; + break; + + case DLT_LINUX_SLL: + /* + * The type field is in the last 2 bytes of the + * DLT_LINUX_SLL header. + */ + handlep->vlan_offset = SLL_HDR_LEN - 2; + break; + + default: + handlep->vlan_offset = -1; /* unknown */ + break; + } + +#if defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS) + if (handle->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO) { + int nsec_tstamps = 1; + + if (setsockopt(sock_fd, SOL_SOCKET, SO_TIMESTAMPNS, &nsec_tstamps, sizeof(nsec_tstamps)) < 0) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "setsockopt: unable to set SO_TIMESTAMPNS"); + close(sock_fd); + return PCAP_ERROR; + } + } +#endif /* defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS) */ + + /* + * We've succeeded. Save the socket FD in the pcap structure. + */ + handle->fd = sock_fd; + +#if defined(SO_BPF_EXTENSIONS) && defined(SKF_AD_VLAN_TAG_PRESENT) + /* + * Can we generate special code for VLAN checks? + * (XXX - what if we need the special code but it's not supported + * by the OS? Is that possible?) + */ + if (getsockopt(sock_fd, SOL_SOCKET, SO_BPF_EXTENSIONS, + &bpf_extensions, &len) == 0) { + if (bpf_extensions >= SKF_AD_VLAN_TAG_PRESENT) { + /* + * Yes, we can. Request that we do so. + */ + handle->bpf_codegen_flags |= BPF_SPECIAL_VLAN_HANDLING; + } + } +#endif /* defined(SO_BPF_EXTENSIONS) && defined(SKF_AD_VLAN_TAG_PRESENT) */ + + return 1; +#else /* HAVE_PF_PACKET_SOCKETS */ + pcap_strlcpy(ebuf, + "New packet capturing interface not supported by build " + "environment", PCAP_ERRBUF_SIZE); + return 0; +#endif /* HAVE_PF_PACKET_SOCKETS */ +} + +#ifdef HAVE_PACKET_RING +/* + * Attempt to activate with memory-mapped access. + * + * On success, returns 1, and sets *status to 0 if there are no warnings + * or to a PCAP_WARNING_ code if there is a warning. + * + * On failure due to lack of support for memory-mapped capture, returns + * 0. + * + * On error, returns -1, and sets *status to the appropriate error code; + * if that is PCAP_ERROR, sets handle->errbuf to the appropriate message. + */ +static int +activate_mmap(pcap_t *handle, int *status) +{ + struct pcap_linux *handlep = handle->priv; + int ret; + + /* + * Attempt to allocate a buffer to hold the contents of one + * packet, for use by the oneshot callback. + */ + handlep->oneshot_buffer = malloc(handle->snapshot); + if (handlep->oneshot_buffer == NULL) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "can't allocate oneshot buffer"); + *status = PCAP_ERROR; + return -1; + } + + if (handle->opt.buffer_size == 0) { + /* by default request 2M for the ring buffer */ + handle->opt.buffer_size = 2*1024*1024; + } + ret = prepare_tpacket_socket(handle); + if (ret == -1) { + free(handlep->oneshot_buffer); + *status = PCAP_ERROR; + return ret; + } + ret = create_ring(handle, status); + if (ret == 0) { + /* + * We don't support memory-mapped capture; our caller + * will fall back on reading from the socket. + */ + free(handlep->oneshot_buffer); + return 0; + } + if (ret == -1) { + /* + * Error attempting to enable memory-mapped capture; + * fail. create_ring() has set *status. + */ + free(handlep->oneshot_buffer); + return -1; + } + + /* + * Success. *status has been set either to 0 if there are no + * warnings or to a PCAP_WARNING_ value if there is a warning. + * + * Override some defaults and inherit the other fields from + * activate_new. + * handle->offset is used to get the current position into the rx ring. + * handle->cc is used to store the ring size. + */ + + switch (handlep->tp_version) { + case TPACKET_V1: + handle->read_op = pcap_read_linux_mmap_v1; + break; + case TPACKET_V1_64: + handle->read_op = pcap_read_linux_mmap_v1_64; + break; +#ifdef HAVE_TPACKET2 + case TPACKET_V2: + handle->read_op = pcap_read_linux_mmap_v2; + break; +#endif +#ifdef HAVE_TPACKET3 + case TPACKET_V3: + handle->read_op = pcap_read_linux_mmap_v3; + break; +#endif + } + handle->cleanup_op = pcap_cleanup_linux_mmap; + handle->setfilter_op = pcap_setfilter_linux_mmap; + handle->setnonblock_op = pcap_setnonblock_mmap; + handle->getnonblock_op = pcap_getnonblock_mmap; + handle->oneshot_callback = pcap_oneshot_mmap; + handle->selectable_fd = handle->fd; + return 1; +} +#else /* HAVE_PACKET_RING */ +static int +activate_mmap(pcap_t *handle _U_, int *status _U_) +{ + return 0; +} +#endif /* HAVE_PACKET_RING */ + +#ifdef HAVE_PACKET_RING + +#if defined(HAVE_TPACKET2) || defined(HAVE_TPACKET3) +/* + * Attempt to set the socket to the specified version of the memory-mapped + * header. + * + * Return 0 if we succeed; return 1 if we fail because that version isn't + * supported; return -1 on any other error, and set handle->errbuf. + */ +static int +init_tpacket(pcap_t *handle, int version, const char *version_str) +{ + struct pcap_linux *handlep = handle->priv; + int val = version; + socklen_t len = sizeof(val); + + /* + * Probe whether kernel supports the specified TPACKET version; + * this also gets the length of the header for that version. + * + * This socket option was introduced in 2.6.27, which was + * also the first release with TPACKET_V2 support. + */ + if (getsockopt(handle->fd, SOL_PACKET, PACKET_HDRLEN, &val, &len) < 0) { + if (errno == ENOPROTOOPT || errno == EINVAL) { + /* + * ENOPROTOOPT means the kernel is too old to + * support PACKET_HDRLEN at all, which means + * it either doesn't support TPACKET at all + * or supports only TPACKET_V1. + */ + return 1; /* no */ + } + + /* Failed to even find out; this is a fatal error. */ + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "can't get %s header len on packet socket", + version_str); + return -1; + } + handlep->tp_hdrlen = val; + + val = version; + if (setsockopt(handle->fd, SOL_PACKET, PACKET_VERSION, &val, + sizeof(val)) < 0) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "can't activate %s on packet socket", version_str); + return -1; + } + handlep->tp_version = version; + + /* + * Reserve space for VLAN tag reconstruction. + * This option was also introduced in 2.6.27. + */ + val = VLAN_TAG_LEN; + if (setsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, &val, + sizeof(val)) < 0) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "can't set up reserve on packet socket"); + return -1; + } + + return 0; +} +#endif /* defined HAVE_TPACKET2 || defined HAVE_TPACKET3 */ + +/* + * If the instruction set for which we're compiling has both 32-bit + * and 64-bit versions, and Linux support for the 64-bit version + * predates TPACKET_V2, define ISA_64_BIT as the .machine value + * you get from uname() for the 64-bit version. Otherwise, leave + * it undefined. (This includes ARM, which has a 64-bit version, + * but Linux support for it appeared well after TPACKET_V2 support + * did, so there should never be a case where 32-bit ARM code is + * running o a 64-bit kernel that only supports TPACKET_V1.) + * + * If we've omitted your favorite such architecture, please contribute + * a patch. (No patch is needed for architectures that are 32-bit-only + * or for which Linux has no support for 32-bit userland - or for which, + * as noted, 64-bit support appeared in Linux after TPACKET_V2 support + * did.) + */ +#if defined(__i386__) +#define ISA_64_BIT "x86_64" +#elif defined(__ppc__) +#define ISA_64_BIT "ppc64" +#elif defined(__sparc__) +#define ISA_64_BIT "sparc64" +#elif defined(__s390__) +#define ISA_64_BIT "s390x" +#elif defined(__mips__) +#define ISA_64_BIT "mips64" +#elif defined(__hppa__) +#define ISA_64_BIT "parisc64" +#endif + +/* + * Attempt to set the socket to version 3 of the memory-mapped header and, + * if that fails because version 3 isn't supported, attempt to fall + * back to version 2. If version 2 isn't supported, just leave it at + * version 1. + * + * Return 1 if we succeed or if we fail because neither version 2 nor 3 is + * supported; return -1 on any other error, and set handle->errbuf. + */ +static int +prepare_tpacket_socket(pcap_t *handle) +{ + struct pcap_linux *handlep = handle->priv; +#if defined(HAVE_TPACKET2) || defined(HAVE_TPACKET3) + int ret; +#endif + +#ifdef HAVE_TPACKET3 + /* + * Try setting the version to TPACKET_V3. + * + * The only mode in which buffering is done on PF_PACKET + * sockets, so that packets might not be delivered + * immediately, is TPACKET_V3 mode. + * + * The buffering cannot be disabled in that mode, so + * if the user has requested immediate mode, we don't + * use TPACKET_V3. + */ + if (!handle->opt.immediate) { + ret = init_tpacket(handle, TPACKET_V3, "TPACKET_V3"); + if (ret == 0) { + /* + * Success. + */ + return 1; + } + if (ret == -1) { + /* + * We failed for some reason other than "the + * kernel doesn't support TPACKET_V3". + */ + return -1; + } + } +#endif /* HAVE_TPACKET3 */ + +#ifdef HAVE_TPACKET2 + /* + * Try setting the version to TPACKET_V2. + */ + ret = init_tpacket(handle, TPACKET_V2, "TPACKET_V2"); + if (ret == 0) { + /* + * Success. + */ + return 1; + } + if (ret == -1) { + /* + * We failed for some reason other than "the + * kernel doesn't support TPACKET_V2". + */ + return -1; + } +#endif /* HAVE_TPACKET2 */ + + /* + * OK, we're using TPACKET_V1, as either that's all the kernel + * supports or it doesn't support TPACKET at all. In the latter + * case, create_ring() will fail, and we'll fall back on non- + * memory-mapped capture. + */ + handlep->tp_version = TPACKET_V1; + handlep->tp_hdrlen = sizeof(struct tpacket_hdr); + +#ifdef ISA_64_BIT + /* + * 32-bit userspace + 64-bit kernel + TPACKET_V1 are not compatible with + * each other due to platform-dependent data type size differences. + * + * If we have a 32-bit userland and a 64-bit kernel, use an + * internally-defined TPACKET_V1_64, with which we use a 64-bit + * version of the data structures. + */ + if (sizeof(long) == 4) { + /* + * This is 32-bit code. + */ + struct utsname utsname; + + if (uname(&utsname) == -1) { + /* + * Failed. + */ + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "uname failed"); + return -1; + } + if (strcmp(utsname.machine, ISA_64_BIT) == 0) { + /* + * uname() tells us the machine is 64-bit, + * so we presumably have a 64-bit kernel. + * + * XXX - this presumes that uname() won't lie + * in 32-bit code and claim that the machine + * has the 32-bit version of the ISA. + */ + handlep->tp_version = TPACKET_V1_64; + handlep->tp_hdrlen = sizeof(struct tpacket_hdr_64); + } + } +#endif + + return 1; +} + +#define MAX(a,b) ((a)>(b)?(a):(b)) + +/* + * Attempt to set up memory-mapped access. + * + * On success, returns 1, and sets *status to 0 if there are no warnings + * or to a PCAP_WARNING_ code if there is a warning. + * + * On failure due to lack of support for memory-mapped capture, returns + * 0. + * + * On error, returns -1, and sets *status to the appropriate error code; + * if that is PCAP_ERROR, sets handle->errbuf to the appropriate message. + */ +static int +create_ring(pcap_t *handle, int *status) +{ + struct pcap_linux *handlep = handle->priv; + unsigned i, j, frames_per_block; +#ifdef HAVE_TPACKET3 + /* + * For sockets using TPACKET_V1 or TPACKET_V2, the extra + * stuff at the end of a struct tpacket_req3 will be + * ignored, so this is OK even for those sockets. + */ + struct tpacket_req3 req; +#else + struct tpacket_req req; +#endif + socklen_t len; + unsigned int sk_type, tp_reserve, maclen, tp_hdrlen, netoff, macoff; + unsigned int frame_size; + + /* + * Start out assuming no warnings or errors. + */ + *status = 0; + + switch (handlep->tp_version) { + + case TPACKET_V1: + case TPACKET_V1_64: +#ifdef HAVE_TPACKET2 + case TPACKET_V2: +#endif + /* Note that with large snapshot length (say 256K, which is + * the default for recent versions of tcpdump, Wireshark, + * TShark, dumpcap or 64K, the value that "-s 0" has given for + * a long time with tcpdump), if we use the snapshot + * length to calculate the frame length, only a few frames + * will be available in the ring even with pretty + * large ring size (and a lot of memory will be unused). + * + * Ideally, we should choose a frame length based on the + * minimum of the specified snapshot length and the maximum + * packet size. That's not as easy as it sounds; consider, + * for example, an 802.11 interface in monitor mode, where + * the frame would include a radiotap header, where the + * maximum radiotap header length is device-dependent. + * + * So, for now, we just do this for Ethernet devices, where + * there's no metadata header, and the link-layer header is + * fixed length. We can get the maximum packet size by + * adding 18, the Ethernet header length plus the CRC length + * (just in case we happen to get the CRC in the packet), to + * the MTU of the interface; we fetch the MTU in the hopes + * that it reflects support for jumbo frames. (Even if the + * interface is just being used for passive snooping, the + * driver might set the size of buffers in the receive ring + * based on the MTU, so that the MTU limits the maximum size + * of packets that we can receive.) + * + * If segmentation/fragmentation or receive offload are + * enabled, we can get reassembled/aggregated packets larger + * than MTU, but bounded to 65535 plus the Ethernet overhead, + * due to kernel and protocol constraints */ + frame_size = handle->snapshot; + if (handle->linktype == DLT_EN10MB) { + unsigned int max_frame_len; + int mtu; + int offload; + + mtu = iface_get_mtu(handle->fd, handle->opt.device, + handle->errbuf); + if (mtu == -1) { + *status = PCAP_ERROR; + return -1; + } + offload = iface_get_offload(handle); + if (offload == -1) { + *status = PCAP_ERROR; + return -1; + } + if (offload) + max_frame_len = MAX(mtu, 65535); + else + max_frame_len = mtu; + max_frame_len += 18; + + if (frame_size > max_frame_len) + frame_size = max_frame_len; + } + + /* NOTE: calculus matching those in tpacket_rcv() + * in linux-2.6/net/packet/af_packet.c + */ + len = sizeof(sk_type); + if (getsockopt(handle->fd, SOL_SOCKET, SO_TYPE, &sk_type, + &len) < 0) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "getsockopt (SO_TYPE)"); + *status = PCAP_ERROR; + return -1; + } +#ifdef PACKET_RESERVE + len = sizeof(tp_reserve); + if (getsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, + &tp_reserve, &len) < 0) { + if (errno != ENOPROTOOPT) { + /* + * ENOPROTOOPT means "kernel doesn't support + * PACKET_RESERVE", in which case we fall back + * as best we can. + */ + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "getsockopt (PACKET_RESERVE)"); + *status = PCAP_ERROR; + return -1; + } + /* + * Older kernel, so we can't use PACKET_RESERVE; + * this means we can't reserver extra space + * for a DLT_LINUX_SLL2 header. + */ + tp_reserve = 0; + } else { + /* + * We can reserve extra space for a DLT_LINUX_SLL2 + * header. Do so. + * + * XXX - we assume that the kernel is still adding + * 16 bytes of extra space; that happens to + * correspond to SLL_HDR_LEN (whether intentionally + * or not - the kernel code has a raw "16" in + * the expression), so we subtract SLL_HDR_LEN + * from SLL2_HDR_LEN to get the additional space + * needed. + * + * XXX - should we use TPACKET_ALIGN(SLL2_HDR_LEN - SLL_HDR_LEN)? + */ + tp_reserve += SLL2_HDR_LEN - SLL_HDR_LEN; + len = sizeof(tp_reserve); + if (setsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, + &tp_reserve, len) < 0) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "setsockopt (PACKET_RESERVE)"); + *status = PCAP_ERROR; + return -1; + } + } +#else + /* + * Build environment for an older kernel, so we can't + * use PACKET_RESERVE; this means we can't reserve + * extra space for a DLT_LINUX_SLL2 header. + */ + tp_reserve = 0; +#endif + maclen = (sk_type == SOCK_DGRAM) ? 0 : MAX_LINKHEADER_SIZE; + /* XXX: in the kernel maclen is calculated from + * LL_ALLOCATED_SPACE(dev) and vnet_hdr.hdr_len + * in: packet_snd() in linux-2.6/net/packet/af_packet.c + * then packet_alloc_skb() in linux-2.6/net/packet/af_packet.c + * then sock_alloc_send_pskb() in linux-2.6/net/core/sock.c + * but I see no way to get those sizes in userspace, + * like for instance with an ifreq ioctl(); + * the best thing I've found so far is MAX_HEADER in + * the kernel part of linux-2.6/include/linux/netdevice.h + * which goes up to 128+48=176; since pcap-linux.c + * defines a MAX_LINKHEADER_SIZE of 256 which is + * greater than that, let's use it.. maybe is it even + * large enough to directly replace macoff.. + */ + tp_hdrlen = TPACKET_ALIGN(handlep->tp_hdrlen) + sizeof(struct sockaddr_ll) ; + netoff = TPACKET_ALIGN(tp_hdrlen + (maclen < 16 ? 16 : maclen)) + tp_reserve; + /* NOTE: AFAICS tp_reserve may break the TPACKET_ALIGN + * of netoff, which contradicts + * linux-2.6/Documentation/networking/packet_mmap.txt + * documenting that: + * "- Gap, chosen so that packet data (Start+tp_net) + * aligns to TPACKET_ALIGNMENT=16" + */ + /* NOTE: in linux-2.6/include/linux/skbuff.h: + * "CPUs often take a performance hit + * when accessing unaligned memory locations" + */ + macoff = netoff - maclen; + req.tp_frame_size = TPACKET_ALIGN(macoff + frame_size); + /* + * Round the buffer size up to a multiple of the + * frame size (rather than rounding down, which + * would give a buffer smaller than our caller asked + * for, and possibly give zero frames if the requested + * buffer size is too small for one frame). + */ + req.tp_frame_nr = (handle->opt.buffer_size + req.tp_frame_size - 1)/req.tp_frame_size; + break; + +#ifdef HAVE_TPACKET3 + case TPACKET_V3: + /* + * If we have TPACKET_V3, we have PACKET_RESERVE. + */ + len = sizeof(tp_reserve); + if (getsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, + &tp_reserve, &len) < 0) { + /* + * Even ENOPROTOOPT is an error - we wouldn't + * be here if the kernel didn't support + * TPACKET_V3, which means it supports + * PACKET_RESERVE. + */ + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "getsockopt (PACKET_RESERVE)"); + *status = PCAP_ERROR; + return -1; + } + /* + * We can reserve extra space for a DLT_LINUX_SLL2 + * header. Do so. + * + * XXX - we assume that the kernel is still adding + * 16 bytes of extra space; that happens to + * correspond to SLL_HDR_LEN (whether intentionally + * or not - the kernel code has a raw "16" in + * the expression), so we subtract SLL_HDR_LEN + * from SLL2_HDR_LEN to get the additional space + * needed. + * + * XXX - should we use TPACKET_ALIGN(SLL2_HDR_LEN - SLL_HDR_LEN)? + */ + tp_reserve += SLL2_HDR_LEN - SLL_HDR_LEN; + len = sizeof(tp_reserve); + if (setsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, + &tp_reserve, len) < 0) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "setsockopt (PACKET_RESERVE)"); + *status = PCAP_ERROR; + return -1; + } + + /* The "frames" for this are actually buffers that + * contain multiple variable-sized frames. + * + * We pick a "frame" size of MAXIMUM_SNAPLEN to leave + * enough room for at least one reasonably-sized packet + * in the "frame". */ + req.tp_frame_size = MAXIMUM_SNAPLEN; + /* + * Round the buffer size up to a multiple of the + * "frame" size (rather than rounding down, which + * would give a buffer smaller than our caller asked + * for, and possibly give zero "frames" if the requested + * buffer size is too small for one "frame"). + */ + req.tp_frame_nr = (handle->opt.buffer_size + req.tp_frame_size - 1)/req.tp_frame_size; + break; +#endif + default: + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "Internal error: unknown TPACKET_ value %u", + handlep->tp_version); + *status = PCAP_ERROR; + return -1; + } + + /* compute the minumum block size that will handle this frame. + * The block has to be page size aligned. + * The max block size allowed by the kernel is arch-dependent and + * it's not explicitly checked here. */ + req.tp_block_size = getpagesize(); + while (req.tp_block_size < req.tp_frame_size) + req.tp_block_size <<= 1; + + frames_per_block = req.tp_block_size/req.tp_frame_size; + + /* + * PACKET_TIMESTAMP was added after linux/net_tstamp.h was, + * so we check for PACKET_TIMESTAMP. We check for + * linux/net_tstamp.h just in case a system somehow has + * PACKET_TIMESTAMP but not linux/net_tstamp.h; that might + * be unnecessary. + * + * SIOCSHWTSTAMP was introduced in the patch that introduced + * linux/net_tstamp.h, so we don't bother checking whether + * SIOCSHWTSTAMP is defined (if your Linux system has + * linux/net_tstamp.h but doesn't define SIOCSHWTSTAMP, your + * Linux system is badly broken). + */ +#if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) + /* + * If we were told to do so, ask the kernel and the driver + * to use hardware timestamps. + * + * Hardware timestamps are only supported with mmapped + * captures. + */ + if (handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER || + handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER_UNSYNCED) { + struct hwtstamp_config hwconfig; + struct ifreq ifr; + int timesource; + + /* + * Ask for hardware time stamps on all packets, + * including transmitted packets. + */ + memset(&hwconfig, 0, sizeof(hwconfig)); + hwconfig.tx_type = HWTSTAMP_TX_ON; + hwconfig.rx_filter = HWTSTAMP_FILTER_ALL; + + memset(&ifr, 0, sizeof(ifr)); + pcap_strlcpy(ifr.ifr_name, handle->opt.device, sizeof(ifr.ifr_name)); + ifr.ifr_data = (void *)&hwconfig; + + if (ioctl(handle->fd, SIOCSHWTSTAMP, &ifr) < 0) { + switch (errno) { + + case EPERM: + /* + * Treat this as an error, as the + * user should try to run this + * with the appropriate privileges - + * and, if they can't, shouldn't + * try requesting hardware time stamps. + */ + *status = PCAP_ERROR_PERM_DENIED; + return -1; + + case EOPNOTSUPP: + case ERANGE: + /* + * Treat this as a warning, as the + * only way to fix the warning is to + * get an adapter that supports hardware + * time stamps for *all* packets. + * (ERANGE means "we support hardware + * time stamps, but for packets matching + * that particular filter", so it means + * "we don't support hardware time stamps + * for all incoming packets" here.) + * + * We'll just fall back on the standard + * host time stamps. + */ + *status = PCAP_WARNING_TSTAMP_TYPE_NOTSUP; + break; + + default: + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "SIOCSHWTSTAMP failed"); + *status = PCAP_ERROR; + return -1; + } + } else { + /* + * Well, that worked. Now specify the type of + * hardware time stamp we want for this + * socket. + */ + if (handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER) { + /* + * Hardware timestamp, synchronized + * with the system clock. + */ + timesource = SOF_TIMESTAMPING_SYS_HARDWARE; + } else { + /* + * PCAP_TSTAMP_ADAPTER_UNSYNCED - hardware + * timestamp, not synchronized with the + * system clock. + */ + timesource = SOF_TIMESTAMPING_RAW_HARDWARE; + } + if (setsockopt(handle->fd, SOL_PACKET, PACKET_TIMESTAMP, + (void *)×ource, sizeof(timesource))) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "can't set PACKET_TIMESTAMP"); + *status = PCAP_ERROR; + return -1; + } + } + } +#endif /* HAVE_LINUX_NET_TSTAMP_H && PACKET_TIMESTAMP */ + + /* ask the kernel to create the ring */ +retry: + req.tp_block_nr = req.tp_frame_nr / frames_per_block; + + /* req.tp_frame_nr is requested to match frames_per_block*req.tp_block_nr */ + req.tp_frame_nr = req.tp_block_nr * frames_per_block; + +#ifdef HAVE_TPACKET3 + /* timeout value to retire block - use the configured buffering timeout, or default if <0. */ + if (handlep->timeout > 0) { + /* Use the user specified timeout as the block timeout */ + req.tp_retire_blk_tov = handlep->timeout; + } else if (handlep->timeout == 0) { + /* + * In pcap, this means "infinite timeout"; TPACKET_V3 + * doesn't support that, so just set it to UINT_MAX + * milliseconds. In the TPACKET_V3 loop, if the + * timeout is 0, and we haven't yet seen any packets, + * and we block and still don't have any packets, we + * keep blocking until we do. + */ + req.tp_retire_blk_tov = UINT_MAX; + } else { + /* + * XXX - this is not valid; use 0, meaning "have the + * kernel pick a default", for now. + */ + req.tp_retire_blk_tov = 0; + } + /* private data not used */ + req.tp_sizeof_priv = 0; + /* Rx ring - feature request bits - none (rxhash will not be filled) */ + req.tp_feature_req_word = 0; +#endif + + if (setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING, + (void *) &req, sizeof(req))) { + if ((errno == ENOMEM) && (req.tp_block_nr > 1)) { + /* + * Memory failure; try to reduce the requested ring + * size. + * + * We used to reduce this by half -- do 5% instead. + * That may result in more iterations and a longer + * startup, but the user will be much happier with + * the resulting buffer size. + */ + if (req.tp_frame_nr < 20) + req.tp_frame_nr -= 1; + else + req.tp_frame_nr -= req.tp_frame_nr/20; + goto retry; + } + if (errno == ENOPROTOOPT) { + /* + * We don't have ring buffer support in this kernel. + */ + return 0; + } + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "can't create rx ring on packet socket"); + *status = PCAP_ERROR; + return -1; + } + + /* memory map the rx ring */ + handlep->mmapbuflen = req.tp_block_nr * req.tp_block_size; + handlep->mmapbuf = mmap(0, handlep->mmapbuflen, + PROT_READ|PROT_WRITE, MAP_SHARED, handle->fd, 0); + if (handlep->mmapbuf == MAP_FAILED) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "can't mmap rx ring"); + + /* clear the allocated ring on error*/ + destroy_ring(handle); + *status = PCAP_ERROR; + return -1; + } + + /* allocate a ring for each frame header pointer*/ + handle->cc = req.tp_frame_nr; + handle->buffer = malloc(handle->cc * sizeof(union thdr *)); + if (!handle->buffer) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "can't allocate ring of frame headers"); + + destroy_ring(handle); + *status = PCAP_ERROR; + return -1; + } + + /* fill the header ring with proper frame ptr*/ + handle->offset = 0; + for (i=0; i<req.tp_block_nr; ++i) { + void *base = &handlep->mmapbuf[i*req.tp_block_size]; + for (j=0; j<frames_per_block; ++j, ++handle->offset) { + RING_GET_CURRENT_FRAME(handle) = base; + base += req.tp_frame_size; + } + } + + handle->bufsize = req.tp_frame_size; + handle->offset = 0; + return 1; +} + +/* free all ring related resources*/ +static void +destroy_ring(pcap_t *handle) +{ + struct pcap_linux *handlep = handle->priv; + + /* tell the kernel to destroy the ring*/ + struct tpacket_req req; + memset(&req, 0, sizeof(req)); + /* do not test for setsockopt failure, as we can't recover from any error */ + (void)setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING, + (void *) &req, sizeof(req)); + + /* if ring is mapped, unmap it*/ + if (handlep->mmapbuf) { + /* do not test for mmap failure, as we can't recover from any error */ + (void)munmap(handlep->mmapbuf, handlep->mmapbuflen); + handlep->mmapbuf = NULL; + } +} + +/* + * Special one-shot callback, used for pcap_next() and pcap_next_ex(), + * for Linux mmapped capture. + * + * The problem is that pcap_next() and pcap_next_ex() expect the packet + * data handed to the callback to be valid after the callback returns, + * but pcap_read_linux_mmap() has to release that packet as soon as + * the callback returns (otherwise, the kernel thinks there's still + * at least one unprocessed packet available in the ring, so a select() + * will immediately return indicating that there's data to process), so, + * in the callback, we have to make a copy of the packet. + * + * Yes, this means that, if the capture is using the ring buffer, using + * pcap_next() or pcap_next_ex() requires more copies than using + * pcap_loop() or pcap_dispatch(). If that bothers you, don't use + * pcap_next() or pcap_next_ex(). + */ +static void +pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h, + const u_char *bytes) +{ + struct oneshot_userdata *sp = (struct oneshot_userdata *)user; + pcap_t *handle = sp->pd; + struct pcap_linux *handlep = handle->priv; + + *sp->hdr = *h; + memcpy(handlep->oneshot_buffer, bytes, h->caplen); + *sp->pkt = handlep->oneshot_buffer; +} + +static void +pcap_cleanup_linux_mmap( pcap_t *handle ) +{ + struct pcap_linux *handlep = handle->priv; + + destroy_ring(handle); + if (handlep->oneshot_buffer != NULL) { + free(handlep->oneshot_buffer); + handlep->oneshot_buffer = NULL; + } + pcap_cleanup_linux(handle); +} + + +static int +pcap_getnonblock_mmap(pcap_t *handle) +{ + struct pcap_linux *handlep = handle->priv; + + /* use negative value of timeout to indicate non blocking ops */ + return (handlep->timeout<0); +} + +static int +pcap_setnonblock_mmap(pcap_t *handle, int nonblock) +{ + struct pcap_linux *handlep = handle->priv; + + /* + * Set the file descriptor to non-blocking mode, as we use + * it for sending packets. + */ + if (pcap_setnonblock_fd(handle, nonblock) == -1) + return -1; + + /* + * Map each value to their corresponding negation to + * preserve the timeout value provided with pcap_set_timeout. + */ + if (nonblock) { + if (handlep->timeout >= 0) { + /* + * Indicate that we're switching to + * non-blocking mode. + */ + handlep->timeout = ~handlep->timeout; + } + } else { + if (handlep->timeout < 0) { + handlep->timeout = ~handlep->timeout; + } + } + /* Update the timeout to use in poll(). */ + set_poll_timeout(handlep); + return 0; +} + +/* + * Get the status field of the ring buffer frame at a specified offset. + */ +static inline int +pcap_get_ring_frame_status(pcap_t *handle, int offset) +{ + struct pcap_linux *handlep = handle->priv; + union thdr h; + + h.raw = RING_GET_FRAME_AT(handle, offset); + switch (handlep->tp_version) { + case TPACKET_V1: + return (h.h1->tp_status); + break; + case TPACKET_V1_64: + return (h.h1_64->tp_status); + break; +#ifdef HAVE_TPACKET2 + case TPACKET_V2: + return (h.h2->tp_status); + break; +#endif +#ifdef HAVE_TPACKET3 + case TPACKET_V3: + return (h.h3->hdr.bh1.block_status); + break; +#endif + } + /* This should not happen. */ + return 0; +} + +#ifndef POLLRDHUP +#define POLLRDHUP 0 +#endif + +/* + * Block waiting for frames to be available. + */ +static int pcap_wait_for_frames_mmap(pcap_t *handle) +{ + struct pcap_linux *handlep = handle->priv; + char c; + struct pollfd pollinfo; + int ret; + + pollinfo.fd = handle->fd; + pollinfo.events = POLLIN; + + do { + /* + * Yes, we do this even in non-blocking mode, as it's + * the only way to get error indications from a + * tpacket socket. + * + * The timeout is 0 in non-blocking mode, so poll() + * returns immediately. + */ + ret = poll(&pollinfo, 1, handlep->poll_timeout); + if (ret < 0 && errno != EINTR) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "can't poll on packet socket"); + return PCAP_ERROR; + } else if (ret > 0 && + (pollinfo.revents & (POLLHUP|POLLRDHUP|POLLERR|POLLNVAL))) { + /* + * There's some indication other than + * "you can read on this descriptor" on + * the descriptor. + */ + if (pollinfo.revents & (POLLHUP | POLLRDHUP)) { + pcap_snprintf(handle->errbuf, + PCAP_ERRBUF_SIZE, + "Hangup on packet socket"); + return PCAP_ERROR; + } + if (pollinfo.revents & POLLERR) { + /* + * A recv() will give us the actual error code. + * + * XXX - make the socket non-blocking? + */ + if (recv(handle->fd, &c, sizeof c, + MSG_PEEK) != -1) + continue; /* what, no error? */ + if (errno == ENETDOWN) { + /* + * The device on which we're + * capturing went away. + * + * XXX - we should really return + * PCAP_ERROR_IFACE_NOT_UP, but + * pcap_dispatch() etc. aren't + * defined to return that. + */ + pcap_snprintf(handle->errbuf, + PCAP_ERRBUF_SIZE, + "The interface went down"); + } else { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "Error condition on packet socket"); + } + return PCAP_ERROR; + } + if (pollinfo.revents & POLLNVAL) { + pcap_snprintf(handle->errbuf, + PCAP_ERRBUF_SIZE, + "Invalid polling request on packet socket"); + return PCAP_ERROR; + } + } + /* check for break loop condition on interrupted syscall*/ + if (handle->break_loop) { + handle->break_loop = 0; + return PCAP_ERROR_BREAK; + } + } while (ret < 0); + return 0; +} + +/* handle a single memory mapped packet */ +static int pcap_handle_packet_mmap( + pcap_t *handle, + pcap_handler callback, + u_char *user, + unsigned char *frame, + unsigned int tp_len, + unsigned int tp_mac, + unsigned int tp_snaplen, + unsigned int tp_sec, + unsigned int tp_usec, + int tp_vlan_tci_valid, + __u16 tp_vlan_tci, + __u16 tp_vlan_tpid) +{ + struct pcap_linux *handlep = handle->priv; + unsigned char *bp; + struct sockaddr_ll *sll; + struct pcap_pkthdr pcaphdr; + unsigned int snaplen = tp_snaplen; + struct utsname utsname; + + /* perform sanity check on internal offset. */ + if (tp_mac + tp_snaplen > handle->bufsize) { + /* + * Report some system information as a debugging aid. + */ + if (uname(&utsname) != -1) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "corrupted frame on kernel ring mac " + "offset %u + caplen %u > frame len %d " + "(kernel %.32s version %s, machine %.16s)", + tp_mac, tp_snaplen, handle->bufsize, + utsname.release, utsname.version, + utsname.machine); + } else { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "corrupted frame on kernel ring mac " + "offset %u + caplen %u > frame len %d", + tp_mac, tp_snaplen, handle->bufsize); + } + return -1; + } + + /* run filter on received packet + * If the kernel filtering is enabled we need to run the + * filter until all the frames present into the ring + * at filter creation time are processed. + * In this case, blocks_to_filter_in_userland is used + * as a counter for the packet we need to filter. + * Note: alternatively it could be possible to stop applying + * the filter when the ring became empty, but it can possibly + * happen a lot later... */ + bp = frame + tp_mac; + + /* if required build in place the sll header*/ + sll = (void *)frame + TPACKET_ALIGN(handlep->tp_hdrlen); + if (handlep->cooked) { + if (handle->linktype == DLT_LINUX_SLL2) { + struct sll2_header *hdrp; + + /* + * The kernel should have left us with enough + * space for an sll header; back up the packet + * data pointer into that space, as that'll be + * the beginning of the packet we pass to the + * callback. + */ + bp -= SLL2_HDR_LEN; + + /* + * Let's make sure that's past the end of + * the tpacket header, i.e. >= + * ((u_char *)thdr + TPACKET_HDRLEN), so we + * don't step on the header when we construct + * the sll header. + */ + if (bp < (u_char *)frame + + TPACKET_ALIGN(handlep->tp_hdrlen) + + sizeof(struct sockaddr_ll)) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "cooked-mode frame doesn't have room for sll header"); + return -1; + } + + /* + * OK, that worked; construct the sll header. + */ + hdrp = (struct sll2_header *)bp; + hdrp->sll2_protocol = sll->sll_protocol; + hdrp->sll2_reserved_mbz = 0; + hdrp->sll2_if_index = htonl(sll->sll_ifindex); + hdrp->sll2_hatype = htons(sll->sll_hatype); + hdrp->sll2_pkttype = sll->sll_pkttype; + hdrp->sll2_halen = sll->sll_halen; + memcpy(hdrp->sll2_addr, sll->sll_addr, SLL_ADDRLEN); + + snaplen += sizeof(struct sll2_header); + } else { + struct sll_header *hdrp; + + /* + * The kernel should have left us with enough + * space for an sll header; back up the packet + * data pointer into that space, as that'll be + * the beginning of the packet we pass to the + * callback. + */ + bp -= SLL_HDR_LEN; + + /* + * Let's make sure that's past the end of + * the tpacket header, i.e. >= + * ((u_char *)thdr + TPACKET_HDRLEN), so we + * don't step on the header when we construct + * the sll header. + */ + if (bp < (u_char *)frame + + TPACKET_ALIGN(handlep->tp_hdrlen) + + sizeof(struct sockaddr_ll)) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "cooked-mode frame doesn't have room for sll header"); + return -1; + } + + /* + * OK, that worked; construct the sll header. + */ + hdrp = (struct sll_header *)bp; + hdrp->sll_pkttype = htons(sll->sll_pkttype); + hdrp->sll_hatype = htons(sll->sll_hatype); + hdrp->sll_halen = htons(sll->sll_halen); + memcpy(hdrp->sll_addr, sll->sll_addr, SLL_ADDRLEN); + hdrp->sll_protocol = sll->sll_protocol; + + snaplen += sizeof(struct sll_header); + } + } + + if (handlep->filter_in_userland && handle->fcode.bf_insns) { + struct bpf_aux_data aux_data; + + aux_data.vlan_tag_present = tp_vlan_tci_valid; + aux_data.vlan_tag = tp_vlan_tci & 0x0fff; + + if (bpf_filter_with_aux_data(handle->fcode.bf_insns, + bp, + tp_len, + snaplen, + &aux_data) == 0) + return 0; + } + + if (!linux_check_direction(handle, sll)) + return 0; + + /* get required packet info from ring header */ + pcaphdr.ts.tv_sec = tp_sec; + pcaphdr.ts.tv_usec = tp_usec; + pcaphdr.caplen = tp_snaplen; + pcaphdr.len = tp_len; + + /* if required build in place the sll header*/ + if (handlep->cooked) { + /* update packet len */ + if (handle->linktype == DLT_LINUX_SLL2) { + pcaphdr.caplen += SLL2_HDR_LEN; + pcaphdr.len += SLL2_HDR_LEN; + } else { + pcaphdr.caplen += SLL_HDR_LEN; + pcaphdr.len += SLL_HDR_LEN; + } + } + +#if defined(HAVE_TPACKET2) || defined(HAVE_TPACKET3) + if (tp_vlan_tci_valid && + handlep->vlan_offset != -1 && + tp_snaplen >= (unsigned int) handlep->vlan_offset) + { + struct vlan_tag *tag; + + /* + * Move everything in the header, except the type field, + * down VLAN_TAG_LEN bytes, to allow us to insert the + * VLAN tag between that stuff and the type field. + */ + bp -= VLAN_TAG_LEN; + memmove(bp, bp + VLAN_TAG_LEN, handlep->vlan_offset); + + /* + * Now insert the tag. + */ + tag = (struct vlan_tag *)(bp + handlep->vlan_offset); + tag->vlan_tpid = htons(tp_vlan_tpid); + tag->vlan_tci = htons(tp_vlan_tci); + + /* + * Add the tag to the packet lengths. + */ + pcaphdr.caplen += VLAN_TAG_LEN; + pcaphdr.len += VLAN_TAG_LEN; + } +#endif + + /* + * The only way to tell the kernel to cut off the + * packet at a snapshot length is with a filter program; + * if there's no filter program, the kernel won't cut + * the packet off. + * + * Trim the snapshot length to be no longer than the + * specified snapshot length. + */ + if (pcaphdr.caplen > (bpf_u_int32)handle->snapshot) + pcaphdr.caplen = handle->snapshot; + + /* pass the packet to the user */ + callback(user, &pcaphdr, bp); + + return 1; +} + +static int +pcap_read_linux_mmap_v1(pcap_t *handle, int max_packets, pcap_handler callback, + u_char *user) +{ + struct pcap_linux *handlep = handle->priv; + union thdr h; + int pkts = 0; + int ret; + + /* wait for frames availability.*/ + h.raw = RING_GET_CURRENT_FRAME(handle); + if (h.h1->tp_status == TP_STATUS_KERNEL) { + /* + * The current frame is owned by the kernel; wait for + * a frame to be handed to us. + */ + ret = pcap_wait_for_frames_mmap(handle); + if (ret) { + return ret; + } + } + + /* non-positive values of max_packets are used to require all + * packets currently available in the ring */ + while ((pkts < max_packets) || PACKET_COUNT_IS_UNLIMITED(max_packets)) { + /* + * Get the current ring buffer frame, and break if + * it's still owned by the kernel. + */ + h.raw = RING_GET_CURRENT_FRAME(handle); + if (h.h1->tp_status == TP_STATUS_KERNEL) + break; + + ret = pcap_handle_packet_mmap( + handle, + callback, + user, + h.raw, + h.h1->tp_len, + h.h1->tp_mac, + h.h1->tp_snaplen, + h.h1->tp_sec, + h.h1->tp_usec, + 0, + 0, + 0); + if (ret == 1) { + pkts++; + handlep->packets_read++; + } else if (ret < 0) { + return ret; + } + + /* + * Hand this block back to the kernel, and, if we're + * counting blocks that need to be filtered in userland + * after having been filtered by the kernel, count + * the one we've just processed. + */ + h.h1->tp_status = TP_STATUS_KERNEL; + if (handlep->blocks_to_filter_in_userland > 0) { + handlep->blocks_to_filter_in_userland--; + if (handlep->blocks_to_filter_in_userland == 0) { + /* + * No more blocks need to be filtered + * in userland. + */ + handlep->filter_in_userland = 0; + } + } + + /* next block */ + if (++handle->offset >= handle->cc) + handle->offset = 0; + + /* check for break loop condition*/ + if (handle->break_loop) { + handle->break_loop = 0; + return PCAP_ERROR_BREAK; + } + } + return pkts; +} + +static int +pcap_read_linux_mmap_v1_64(pcap_t *handle, int max_packets, pcap_handler callback, + u_char *user) +{ + struct pcap_linux *handlep = handle->priv; + union thdr h; + int pkts = 0; + int ret; + + /* wait for frames availability.*/ + h.raw = RING_GET_CURRENT_FRAME(handle); + if (h.h1_64->tp_status == TP_STATUS_KERNEL) { + /* + * The current frame is owned by the kernel; wait for + * a frame to be handed to us. + */ + ret = pcap_wait_for_frames_mmap(handle); + if (ret) { + return ret; + } + } + + /* non-positive values of max_packets are used to require all + * packets currently available in the ring */ + while ((pkts < max_packets) || PACKET_COUNT_IS_UNLIMITED(max_packets)) { + /* + * Get the current ring buffer frame, and break if + * it's still owned by the kernel. + */ + h.raw = RING_GET_CURRENT_FRAME(handle); + if (h.h1_64->tp_status == TP_STATUS_KERNEL) + break; + + ret = pcap_handle_packet_mmap( + handle, + callback, + user, + h.raw, + h.h1_64->tp_len, + h.h1_64->tp_mac, + h.h1_64->tp_snaplen, + h.h1_64->tp_sec, + h.h1_64->tp_usec, + 0, + 0, + 0); + if (ret == 1) { + pkts++; + handlep->packets_read++; + } else if (ret < 0) { + return ret; + } + + /* + * Hand this block back to the kernel, and, if we're + * counting blocks that need to be filtered in userland + * after having been filtered by the kernel, count + * the one we've just processed. + */ + h.h1_64->tp_status = TP_STATUS_KERNEL; + if (handlep->blocks_to_filter_in_userland > 0) { + handlep->blocks_to_filter_in_userland--; + if (handlep->blocks_to_filter_in_userland == 0) { + /* + * No more blocks need to be filtered + * in userland. + */ + handlep->filter_in_userland = 0; + } + } + + /* next block */ + if (++handle->offset >= handle->cc) + handle->offset = 0; + + /* check for break loop condition*/ + if (handle->break_loop) { + handle->break_loop = 0; + return PCAP_ERROR_BREAK; + } + } + return pkts; +} + +#ifdef HAVE_TPACKET2 +static int +pcap_read_linux_mmap_v2(pcap_t *handle, int max_packets, pcap_handler callback, + u_char *user) +{ + struct pcap_linux *handlep = handle->priv; + union thdr h; + int pkts = 0; + int ret; + + /* wait for frames availability.*/ + h.raw = RING_GET_CURRENT_FRAME(handle); + if (h.h2->tp_status == TP_STATUS_KERNEL) { + /* + * The current frame is owned by the kernel; wait for + * a frame to be handed to us. + */ + ret = pcap_wait_for_frames_mmap(handle); + if (ret) { + return ret; + } + } + + /* non-positive values of max_packets are used to require all + * packets currently available in the ring */ + while ((pkts < max_packets) || PACKET_COUNT_IS_UNLIMITED(max_packets)) { + /* + * Get the current ring buffer frame, and break if + * it's still owned by the kernel. + */ + h.raw = RING_GET_CURRENT_FRAME(handle); + if (h.h2->tp_status == TP_STATUS_KERNEL) + break; + + ret = pcap_handle_packet_mmap( + handle, + callback, + user, + h.raw, + h.h2->tp_len, + h.h2->tp_mac, + h.h2->tp_snaplen, + h.h2->tp_sec, + handle->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO ? h.h2->tp_nsec : h.h2->tp_nsec / 1000, + VLAN_VALID(h.h2, h.h2), + h.h2->tp_vlan_tci, + VLAN_TPID(h.h2, h.h2)); + if (ret == 1) { + pkts++; + handlep->packets_read++; + } else if (ret < 0) { + return ret; + } + + /* + * Hand this block back to the kernel, and, if we're + * counting blocks that need to be filtered in userland + * after having been filtered by the kernel, count + * the one we've just processed. + */ + h.h2->tp_status = TP_STATUS_KERNEL; + if (handlep->blocks_to_filter_in_userland > 0) { + handlep->blocks_to_filter_in_userland--; + if (handlep->blocks_to_filter_in_userland == 0) { + /* + * No more blocks need to be filtered + * in userland. + */ + handlep->filter_in_userland = 0; + } + } + + /* next block */ + if (++handle->offset >= handle->cc) + handle->offset = 0; + + /* check for break loop condition*/ + if (handle->break_loop) { + handle->break_loop = 0; + return PCAP_ERROR_BREAK; + } + } + return pkts; +} +#endif /* HAVE_TPACKET2 */ + +#ifdef HAVE_TPACKET3 +static int +pcap_read_linux_mmap_v3(pcap_t *handle, int max_packets, pcap_handler callback, + u_char *user) +{ + struct pcap_linux *handlep = handle->priv; + union thdr h; + int pkts = 0; + int ret; + +again: + if (handlep->current_packet == NULL) { + /* wait for frames availability.*/ + h.raw = RING_GET_CURRENT_FRAME(handle); + if (h.h3->hdr.bh1.block_status == TP_STATUS_KERNEL) { + /* + * The current frame is owned by the kernel; wait + * for a frame to be handed to us. + */ + ret = pcap_wait_for_frames_mmap(handle); + if (ret) { + return ret; + } + } + } + h.raw = RING_GET_CURRENT_FRAME(handle); + if (h.h3->hdr.bh1.block_status == TP_STATUS_KERNEL) { + if (pkts == 0 && handlep->timeout == 0) { + /* Block until we see a packet. */ + goto again; + } + return pkts; + } + + /* non-positive values of max_packets are used to require all + * packets currently available in the ring */ + while ((pkts < max_packets) || PACKET_COUNT_IS_UNLIMITED(max_packets)) { + int packets_to_read; + + if (handlep->current_packet == NULL) { + h.raw = RING_GET_CURRENT_FRAME(handle); + if (h.h3->hdr.bh1.block_status == TP_STATUS_KERNEL) + break; + + handlep->current_packet = h.raw + h.h3->hdr.bh1.offset_to_first_pkt; + handlep->packets_left = h.h3->hdr.bh1.num_pkts; + } + packets_to_read = handlep->packets_left; + + if (!PACKET_COUNT_IS_UNLIMITED(max_packets) && + packets_to_read > (max_packets - pkts)) { + /* + * We've been given a maximum number of packets + * to process, and there are more packets in + * this buffer than that. Only process enough + * of them to get us up to that maximum. + */ + packets_to_read = max_packets - pkts; + } + + while (packets_to_read-- && !handle->break_loop) { + struct tpacket3_hdr* tp3_hdr = (struct tpacket3_hdr*) handlep->current_packet; + ret = pcap_handle_packet_mmap( + handle, + callback, + user, + handlep->current_packet, + tp3_hdr->tp_len, + tp3_hdr->tp_mac, + tp3_hdr->tp_snaplen, + tp3_hdr->tp_sec, + handle->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO ? tp3_hdr->tp_nsec : tp3_hdr->tp_nsec / 1000, + VLAN_VALID(tp3_hdr, &tp3_hdr->hv1), + tp3_hdr->hv1.tp_vlan_tci, + VLAN_TPID(tp3_hdr, &tp3_hdr->hv1)); + if (ret == 1) { + pkts++; + handlep->packets_read++; + } else if (ret < 0) { + handlep->current_packet = NULL; + return ret; + } + handlep->current_packet += tp3_hdr->tp_next_offset; + handlep->packets_left--; + } + + if (handlep->packets_left <= 0) { + /* + * Hand this block back to the kernel, and, if + * we're counting blocks that need to be + * filtered in userland after having been + * filtered by the kernel, count the one we've + * just processed. + */ + h.h3->hdr.bh1.block_status = TP_STATUS_KERNEL; + if (handlep->blocks_to_filter_in_userland > 0) { + handlep->blocks_to_filter_in_userland--; + if (handlep->blocks_to_filter_in_userland == 0) { + /* + * No more blocks need to be filtered + * in userland. + */ + handlep->filter_in_userland = 0; + } + } + + /* next block */ + if (++handle->offset >= handle->cc) + handle->offset = 0; + + handlep->current_packet = NULL; + } + + /* check for break loop condition*/ + if (handle->break_loop) { + handle->break_loop = 0; + return PCAP_ERROR_BREAK; + } + } + if (pkts == 0 && handlep->timeout == 0) { + /* Block until we see a packet. */ + goto again; + } + return pkts; +} +#endif /* HAVE_TPACKET3 */ + +static int +pcap_setfilter_linux_mmap(pcap_t *handle, struct bpf_program *filter) +{ + struct pcap_linux *handlep = handle->priv; + int n, offset; + int ret; + + /* + * Don't rewrite "ret" instructions; we don't need to, as + * we're not reading packets with recvmsg(), and we don't + * want to, as, by not rewriting them, the kernel can avoid + * copying extra data. + */ + ret = pcap_setfilter_linux_common(handle, filter, 1); + if (ret < 0) + return ret; + + /* + * If we're filtering in userland, there's nothing to do; + * the new filter will be used for the next packet. + */ + if (handlep->filter_in_userland) + return ret; + + /* + * We're filtering in the kernel; the packets present in + * all blocks currently in the ring were already filtered + * by the old filter, and so will need to be filtered in + * userland by the new filter. + * + * Get an upper bound for the number of such blocks; first, + * walk the ring backward and count the free blocks. + */ + offset = handle->offset; + if (--offset < 0) + offset = handle->cc - 1; + for (n=0; n < handle->cc; ++n) { + if (--offset < 0) + offset = handle->cc - 1; + if (pcap_get_ring_frame_status(handle, offset) != TP_STATUS_KERNEL) + break; + } + + /* + * If we found free blocks, decrement the count of free + * blocks by 1, just in case we lost a race with another + * thread of control that was adding a packet while + * we were counting and that had run the filter before + * we changed it. + * + * XXX - could there be more than one block added in + * this fashion? + * + * XXX - is there a way to avoid that race, e.g. somehow + * wait for all packets that passed the old filter to + * be added to the ring? + */ + if (n != 0) + n--; + + /* + * Set the count of blocks worth of packets to filter + * in userland to the total number of blocks in the + * ring minus the number of free blocks we found, and + * turn on userland filtering. (The count of blocks + * worth of packets to filter in userland is guaranteed + * not to be zero - n, above, couldn't be set to a + * value > handle->cc, and if it were equal to + * handle->cc, it wouldn't be zero, and thus would + * be decremented to handle->cc - 1.) + */ + handlep->blocks_to_filter_in_userland = handle->cc - n; + handlep->filter_in_userland = 1; + return ret; +} + +#endif /* HAVE_PACKET_RING */ + + +#ifdef HAVE_PF_PACKET_SOCKETS +/* + * Return the index of the given device name. Fill ebuf and return + * -1 on failure. + */ +static int +iface_get_id(int fd, const char *device, char *ebuf) +{ + struct ifreq ifr; + + memset(&ifr, 0, sizeof(ifr)); + pcap_strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); + + if (ioctl(fd, SIOCGIFINDEX, &ifr) == -1) { + pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, + errno, "SIOCGIFINDEX"); + return -1; + } + + return ifr.ifr_ifindex; +} + +/* + * Bind the socket associated with FD to the given device. + * Return 1 on success, 0 if we should try a SOCK_PACKET socket, + * or a PCAP_ERROR_ value on a hard error. + */ +static int +iface_bind(int fd, int ifindex, char *ebuf, int protocol) +{ + struct sockaddr_ll sll; + int err; + socklen_t errlen = sizeof(err); + + memset(&sll, 0, sizeof(sll)); + sll.sll_family = AF_PACKET; + sll.sll_ifindex = ifindex; + sll.sll_protocol = protocol; + + if (bind(fd, (struct sockaddr *) &sll, sizeof(sll)) == -1) { + if (errno == ENETDOWN) { + /* + * Return a "network down" indication, so that + * the application can report that rather than + * saying we had a mysterious failure and + * suggest that they report a problem to the + * libpcap developers. + */ + return PCAP_ERROR_IFACE_NOT_UP; + } else { + pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, + errno, "bind"); + return PCAP_ERROR; + } + } + + /* Any pending errors, e.g., network is down? */ + + if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) { + pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, + errno, "getsockopt (SO_ERROR)"); + return 0; + } + + if (err == ENETDOWN) { + /* + * Return a "network down" indication, so that + * the application can report that rather than + * saying we had a mysterious failure and + * suggest that they report a problem to the + * libpcap developers. + */ + return PCAP_ERROR_IFACE_NOT_UP; + } else if (err > 0) { + pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, + err, "bind"); + return 0; + } + + return 1; +} + +#ifdef IW_MODE_MONITOR +/* + * Check whether the device supports the Wireless Extensions. + * Returns 1 if it does, 0 if it doesn't, PCAP_ERROR_NO_SUCH_DEVICE + * if the device doesn't even exist. + */ +static int +has_wext(int sock_fd, const char *device, char *ebuf) +{ + struct iwreq ireq; + int ret; + + if (is_bonding_device(sock_fd, device)) + return 0; /* bonding device, so don't even try */ + + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + if (ioctl(sock_fd, SIOCGIWNAME, &ireq) >= 0) + return 1; /* yes */ + if (errno == ENODEV) + ret = PCAP_ERROR_NO_SUCH_DEVICE; + else + ret = 0; + pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, errno, + "%s: SIOCGIWNAME", device); + return ret; +} + +/* + * Per me si va ne la citta dolente, + * Per me si va ne l'etterno dolore, + * ... + * Lasciate ogne speranza, voi ch'intrate. + * + * XXX - airmon-ng does special stuff with the Orinoco driver and the + * wlan-ng driver. + */ +typedef enum { + MONITOR_WEXT, + MONITOR_HOSTAP, + MONITOR_PRISM, + MONITOR_PRISM54, + MONITOR_ACX100, + MONITOR_RT2500, + MONITOR_RT2570, + MONITOR_RT73, + MONITOR_RTL8XXX +} monitor_type; + +/* + * Use the Wireless Extensions, if we have them, to try to turn monitor mode + * on if it's not already on. + * + * Returns 1 on success, 0 if we don't support the Wireless Extensions + * on this device, or a PCAP_ERROR_ value if we do support them but + * we weren't able to turn monitor mode on. + */ +static int +enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, const char *device) +{ + /* + * XXX - at least some adapters require non-Wireless Extensions + * mechanisms to turn monitor mode on. + * + * Atheros cards might require that a separate "monitor virtual access + * point" be created, with later versions of the madwifi driver. + * airmon-ng does "wlanconfig ath create wlandev {if} wlanmode + * monitor -bssid", which apparently spits out a line "athN" + * where "athN" is the monitor mode device. To leave monitor + * mode, it destroys the monitor mode device. + * + * Some Intel Centrino adapters might require private ioctls to get + * radio headers; the ipw2200 and ipw3945 drivers allow you to + * configure a separate "rtapN" interface to capture in monitor + * mode without preventing the adapter from operating normally. + * (airmon-ng doesn't appear to use that, though.) + * + * It would be Truly Wonderful if mac80211 and nl80211 cleaned this + * up, and if all drivers were converted to mac80211 drivers. + * + * If interface {if} is a mac80211 driver, the file + * /sys/class/net/{if}/phy80211 is a symlink to + * /sys/class/ieee80211/{phydev}, for some {phydev}. + * + * On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at + * least, has a "wmaster0" device and a "wlan0" device; the + * latter is the one with the IP address. Both show up in + * "tcpdump -D" output. Capturing on the wmaster0 device + * captures with 802.11 headers. + * + * airmon-ng searches through /sys/class/net for devices named + * monN, starting with mon0; as soon as one *doesn't* exist, + * it chooses that as the monitor device name. If the "iw" + * command exists, it does "iw dev {if} interface add {monif} + * type monitor", where {monif} is the monitor device. It + * then (sigh) sleeps .1 second, and then configures the + * device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface + * is a file, it writes {mondev}, without a newline, to that file, + * and again (sigh) sleeps .1 second, and then iwconfig's that + * device into monitor mode and configures it up. Otherwise, + * you can't do monitor mode. + * + * All these devices are "glued" together by having the + * /sys/class/net/{device}/phy80211 links pointing to the same + * place, so, given a wmaster, wlan, or mon device, you can + * find the other devices by looking for devices with + * the same phy80211 link. + * + * To turn monitor mode off, delete the monitor interface, + * either with "iw dev {monif} interface del" or by sending + * {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface + * + * Note: if you try to create a monitor device named "monN", and + * there's already a "monN" device, it fails, as least with + * the netlink interface (which is what iw uses), with a return + * value of -ENFILE. (Return values are negative errnos.) We + * could probably use that to find an unused device. + */ + struct pcap_linux *handlep = handle->priv; + int err; + struct iwreq ireq; + struct iw_priv_args *priv; + monitor_type montype; + int i; + __u32 cmd; + struct ifreq ifr; + int oldflags; + int args[2]; + int channel; + + /* + * Does this device *support* the Wireless Extensions? + */ + err = has_wext(sock_fd, device, handle->errbuf); + if (err <= 0) + return err; /* either it doesn't or the device doesn't even exist */ + /* + * Start out assuming we have no private extensions to control + * radio metadata. + */ + montype = MONITOR_WEXT; + cmd = 0; + + /* + * Try to get all the Wireless Extensions private ioctls + * supported by this device. + * + * First, get the size of the buffer we need, by supplying no + * buffer and a length of 0. If the device supports private + * ioctls, it should return E2BIG, with ireq.u.data.length set + * to the length we need. If it doesn't support them, it should + * return EOPNOTSUPP. + */ + memset(&ireq, 0, sizeof ireq); + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.u.data.pointer = (void *)args; + ireq.u.data.length = 0; + ireq.u.data.flags = 0; + if (ioctl(sock_fd, SIOCGIWPRIV, &ireq) != -1) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: SIOCGIWPRIV with a zero-length buffer didn't fail!", + device); + return PCAP_ERROR; + } + if (errno != EOPNOTSUPP) { + /* + * OK, it's not as if there are no private ioctls. + */ + if (errno != E2BIG) { + /* + * Failed. + */ + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "%s: SIOCGIWPRIV", device); + return PCAP_ERROR; + } + + /* + * OK, try to get the list of private ioctls. + */ + priv = malloc(ireq.u.data.length * sizeof (struct iw_priv_args)); + if (priv == NULL) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "malloc"); + return PCAP_ERROR; + } + ireq.u.data.pointer = (void *)priv; + if (ioctl(sock_fd, SIOCGIWPRIV, &ireq) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "%s: SIOCGIWPRIV", device); + free(priv); + return PCAP_ERROR; + } + + /* + * Look for private ioctls to turn monitor mode on or, if + * monitor mode is on, to set the header type. + */ + for (i = 0; i < ireq.u.data.length; i++) { + if (strcmp(priv[i].name, "monitor_type") == 0) { + /* + * Hostap driver, use this one. + * Set monitor mode first. + * You can set it to 0 to get DLT_IEEE80211, + * 1 to get DLT_PRISM, 2 to get + * DLT_IEEE80211_RADIO_AVS, and, with more + * recent versions of the driver, 3 to get + * DLT_IEEE80211_RADIO. + */ + if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) + break; + if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) + break; + if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) + break; + montype = MONITOR_HOSTAP; + cmd = priv[i].cmd; + break; + } + if (strcmp(priv[i].name, "set_prismhdr") == 0) { + /* + * Prism54 driver, use this one. + * Set monitor mode first. + * You can set it to 2 to get DLT_IEEE80211 + * or 3 or get DLT_PRISM. + */ + if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) + break; + if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) + break; + if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) + break; + montype = MONITOR_PRISM54; + cmd = priv[i].cmd; + break; + } + if (strcmp(priv[i].name, "forceprismheader") == 0) { + /* + * RT2570 driver, use this one. + * Do this after turning monitor mode on. + * You can set it to 1 to get DLT_PRISM or 2 + * to get DLT_IEEE80211. + */ + if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) + break; + if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) + break; + if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) + break; + montype = MONITOR_RT2570; + cmd = priv[i].cmd; + break; + } + if (strcmp(priv[i].name, "forceprism") == 0) { + /* + * RT73 driver, use this one. + * Do this after turning monitor mode on. + * Its argument is a *string*; you can + * set it to "1" to get DLT_PRISM or "2" + * to get DLT_IEEE80211. + */ + if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_CHAR) + break; + if (priv[i].set_args & IW_PRIV_SIZE_FIXED) + break; + montype = MONITOR_RT73; + cmd = priv[i].cmd; + break; + } + if (strcmp(priv[i].name, "prismhdr") == 0) { + /* + * One of the RTL8xxx drivers, use this one. + * It can only be done after monitor mode + * has been turned on. You can set it to 1 + * to get DLT_PRISM or 0 to get DLT_IEEE80211. + */ + if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) + break; + if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) + break; + if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) + break; + montype = MONITOR_RTL8XXX; + cmd = priv[i].cmd; + break; + } + if (strcmp(priv[i].name, "rfmontx") == 0) { + /* + * RT2500 or RT61 driver, use this one. + * It has one one-byte parameter; set + * u.data.length to 1 and u.data.pointer to + * point to the parameter. + * It doesn't itself turn monitor mode on. + * You can set it to 1 to allow transmitting + * in monitor mode(?) and get DLT_IEEE80211, + * or set it to 0 to disallow transmitting in + * monitor mode(?) and get DLT_PRISM. + */ + if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) + break; + if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 2) + break; + montype = MONITOR_RT2500; + cmd = priv[i].cmd; + break; + } + if (strcmp(priv[i].name, "monitor") == 0) { + /* + * Either ACX100 or hostap, use this one. + * It turns monitor mode on. + * If it takes two arguments, it's ACX100; + * the first argument is 1 for DLT_PRISM + * or 2 for DLT_IEEE80211, and the second + * argument is the channel on which to + * run. If it takes one argument, it's + * HostAP, and the argument is 2 for + * DLT_IEEE80211 and 3 for DLT_PRISM. + * + * If we see this, we don't quit, as this + * might be a version of the hostap driver + * that also supports "monitor_type". + */ + if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) + break; + if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) + break; + switch (priv[i].set_args & IW_PRIV_SIZE_MASK) { + + case 1: + montype = MONITOR_PRISM; + cmd = priv[i].cmd; + break; + + case 2: + montype = MONITOR_ACX100; + cmd = priv[i].cmd; + break; + + default: + break; + } + } + } + free(priv); + } + + /* + * XXX - ipw3945? islism? + */ + + /* + * Get the old mode. + */ + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + if (ioctl(sock_fd, SIOCGIWMODE, &ireq) == -1) { + /* + * We probably won't be able to set the mode, either. + */ + return PCAP_ERROR_RFMON_NOTSUP; + } + + /* + * Is it currently in monitor mode? + */ + if (ireq.u.mode == IW_MODE_MONITOR) { + /* + * Yes. Just leave things as they are. + * We don't offer multiple link-layer types, as + * changing the link-layer type out from under + * somebody else capturing in monitor mode would + * be considered rude. + */ + return 1; + } + /* + * No. We have to put the adapter into rfmon mode. + */ + + /* + * If we haven't already done so, arrange to have + * "pcap_close_all()" called when we exit. + */ + if (!pcap_do_addexit(handle)) { + /* + * "atexit()" failed; don't put the interface + * in rfmon mode, just give up. + */ + return PCAP_ERROR_RFMON_NOTSUP; + } + + /* + * Save the old mode. + */ + handlep->oldmode = ireq.u.mode; + + /* + * Put the adapter in rfmon mode. How we do this depends + * on whether we have a special private ioctl or not. + */ + if (montype == MONITOR_PRISM) { + /* + * We have the "monitor" private ioctl, but none of + * the other private ioctls. Use this, and select + * the Prism header. + * + * If it fails, just fall back on SIOCSIWMODE. + */ + memset(&ireq, 0, sizeof ireq); + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.u.data.length = 1; /* 1 argument */ + args[0] = 3; /* request Prism header */ + memcpy(ireq.u.name, args, sizeof (int)); + if (ioctl(sock_fd, cmd, &ireq) != -1) { + /* + * Success. + * Note that we have to put the old mode back + * when we close the device. + */ + handlep->must_do_on_close |= MUST_CLEAR_RFMON; + + /* + * Add this to the list of pcaps to close + * when we exit. + */ + pcap_add_to_pcaps_to_close(handle); + + return 1; + } + + /* + * Failure. Fall back on SIOCSIWMODE. + */ + } + + /* + * First, take the interface down if it's up; otherwise, we + * might get EBUSY. + */ + memset(&ifr, 0, sizeof(ifr)); + pcap_strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); + if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "%s: Can't get flags", device); + return PCAP_ERROR; + } + oldflags = 0; + if (ifr.ifr_flags & IFF_UP) { + oldflags = ifr.ifr_flags; + ifr.ifr_flags &= ~IFF_UP; + if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "%s: Can't set flags", + device); + return PCAP_ERROR; + } + } + + /* + * Then turn monitor mode on. + */ + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.u.mode = IW_MODE_MONITOR; + if (ioctl(sock_fd, SIOCSIWMODE, &ireq) == -1) { + /* + * Scientist, you've failed. + * Bring the interface back up if we shut it down. + */ + ifr.ifr_flags = oldflags; + if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "%s: Can't set flags", + device); + return PCAP_ERROR; + } + return PCAP_ERROR_RFMON_NOTSUP; + } + + /* + * XXX - airmon-ng does "iwconfig {if} key off" after setting + * monitor mode and setting the channel, and then does + * "iwconfig up". + */ + + /* + * Now select the appropriate radio header. + */ + switch (montype) { + + case MONITOR_WEXT: + /* + * We don't have any private ioctl to set the header. + */ + break; + + case MONITOR_HOSTAP: + /* + * Try to select the radiotap header. + */ + memset(&ireq, 0, sizeof ireq); + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + args[0] = 3; /* request radiotap header */ + memcpy(ireq.u.name, args, sizeof (int)); + if (ioctl(sock_fd, cmd, &ireq) != -1) + break; /* success */ + + /* + * That failed. Try to select the AVS header. + */ + memset(&ireq, 0, sizeof ireq); + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + args[0] = 2; /* request AVS header */ + memcpy(ireq.u.name, args, sizeof (int)); + if (ioctl(sock_fd, cmd, &ireq) != -1) + break; /* success */ + + /* + * That failed. Try to select the Prism header. + */ + memset(&ireq, 0, sizeof ireq); + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + args[0] = 1; /* request Prism header */ + memcpy(ireq.u.name, args, sizeof (int)); + ioctl(sock_fd, cmd, &ireq); + break; + + case MONITOR_PRISM: + /* + * The private ioctl failed. + */ + break; + + case MONITOR_PRISM54: + /* + * Select the Prism header. + */ + memset(&ireq, 0, sizeof ireq); + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + args[0] = 3; /* request Prism header */ + memcpy(ireq.u.name, args, sizeof (int)); + ioctl(sock_fd, cmd, &ireq); + break; + + case MONITOR_ACX100: + /* + * Get the current channel. + */ + memset(&ireq, 0, sizeof ireq); + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + if (ioctl(sock_fd, SIOCGIWFREQ, &ireq) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "%s: SIOCGIWFREQ", device); + return PCAP_ERROR; + } + channel = ireq.u.freq.m; + + /* + * Select the Prism header, and set the channel to the + * current value. + */ + memset(&ireq, 0, sizeof ireq); + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + args[0] = 1; /* request Prism header */ + args[1] = channel; /* set channel */ + memcpy(ireq.u.name, args, 2*sizeof (int)); + ioctl(sock_fd, cmd, &ireq); + break; + + case MONITOR_RT2500: + /* + * Disallow transmission - that turns on the + * Prism header. + */ + memset(&ireq, 0, sizeof ireq); + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + args[0] = 0; /* disallow transmitting */ + memcpy(ireq.u.name, args, sizeof (int)); + ioctl(sock_fd, cmd, &ireq); + break; + + case MONITOR_RT2570: + /* + * Force the Prism header. + */ + memset(&ireq, 0, sizeof ireq); + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + args[0] = 1; /* request Prism header */ + memcpy(ireq.u.name, args, sizeof (int)); + ioctl(sock_fd, cmd, &ireq); + break; + + case MONITOR_RT73: + /* + * Force the Prism header. + */ + memset(&ireq, 0, sizeof ireq); + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.u.data.length = 1; /* 1 argument */ + ireq.u.data.pointer = "1"; + ireq.u.data.flags = 0; + ioctl(sock_fd, cmd, &ireq); + break; + + case MONITOR_RTL8XXX: + /* + * Force the Prism header. + */ + memset(&ireq, 0, sizeof ireq); + pcap_strlcpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + args[0] = 1; /* request Prism header */ + memcpy(ireq.u.name, args, sizeof (int)); + ioctl(sock_fd, cmd, &ireq); + break; + } + + /* + * Now bring the interface back up if we brought it down. + */ + if (oldflags != 0) { + ifr.ifr_flags = oldflags; + if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "%s: Can't set flags", + device); + + /* + * At least try to restore the old mode on the + * interface. + */ + if (ioctl(handle->fd, SIOCSIWMODE, &ireq) == -1) { + /* + * Scientist, you've failed. + */ + fprintf(stderr, + "Can't restore interface wireless mode (SIOCSIWMODE failed: %s).\n" + "Please adjust manually.\n", + strerror(errno)); + } + return PCAP_ERROR; + } + } + + /* + * Note that we have to put the old mode back when we + * close the device. + */ + handlep->must_do_on_close |= MUST_CLEAR_RFMON; + + /* + * Add this to the list of pcaps to close when we exit. + */ + pcap_add_to_pcaps_to_close(handle); + + return 1; +} +#endif /* IW_MODE_MONITOR */ + +/* + * Try various mechanisms to enter monitor mode. + */ +static int +enter_rfmon_mode(pcap_t *handle, int sock_fd, const char *device) +{ +#if defined(HAVE_LIBNL) || defined(IW_MODE_MONITOR) + int ret; +#endif + +#ifdef HAVE_LIBNL + ret = enter_rfmon_mode_mac80211(handle, sock_fd, device); + if (ret < 0) + return ret; /* error attempting to do so */ + if (ret == 1) + return 1; /* success */ +#endif /* HAVE_LIBNL */ + +#ifdef IW_MODE_MONITOR + ret = enter_rfmon_mode_wext(handle, sock_fd, device); + if (ret < 0) + return ret; /* error attempting to do so */ + if (ret == 1) + return 1; /* success */ +#endif /* IW_MODE_MONITOR */ + + /* + * Either none of the mechanisms we know about work or none + * of those mechanisms are available, so we can't do monitor + * mode. + */ + return 0; +} + +#if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) +/* + * Map SOF_TIMESTAMPING_ values to PCAP_TSTAMP_ values. + */ +static const struct { + int soft_timestamping_val; + int pcap_tstamp_val; +} sof_ts_type_map[3] = { + { SOF_TIMESTAMPING_SOFTWARE, PCAP_TSTAMP_HOST }, + { SOF_TIMESTAMPING_SYS_HARDWARE, PCAP_TSTAMP_ADAPTER }, + { SOF_TIMESTAMPING_RAW_HARDWARE, PCAP_TSTAMP_ADAPTER_UNSYNCED } +}; +#define NUM_SOF_TIMESTAMPING_TYPES (sizeof sof_ts_type_map / sizeof sof_ts_type_map[0]) + +/* + * Set the list of time stamping types to include all types. + */ +static void +iface_set_all_ts_types(pcap_t *handle) +{ + u_int i; + + handle->tstamp_type_count = NUM_SOF_TIMESTAMPING_TYPES; + handle->tstamp_type_list = malloc(NUM_SOF_TIMESTAMPING_TYPES * sizeof(u_int)); + for (i = 0; i < NUM_SOF_TIMESTAMPING_TYPES; i++) + handle->tstamp_type_list[i] = sof_ts_type_map[i].pcap_tstamp_val; +} + +#ifdef ETHTOOL_GET_TS_INFO +/* + * Get a list of time stamping capabilities. + */ +static int +iface_ethtool_get_ts_info(const char *device, pcap_t *handle, char *ebuf) +{ + int fd; + struct ifreq ifr; + struct ethtool_ts_info info; + int num_ts_types; + u_int i, j; + + /* + * This doesn't apply to the "any" device; you can't say "turn on + * hardware time stamping for all devices that exist now and arrange + * that it be turned on for any device that appears in the future", + * and not all devices even necessarily *support* hardware time + * stamping, so don't report any time stamp types. + */ + if (strcmp(device, "any") == 0) { + handle->tstamp_type_list = NULL; + return 0; + } + + /* + * Create a socket from which to fetch time stamping capabilities. + */ + fd = socket(PF_UNIX, SOCK_RAW, 0); + if (fd < 0) { + pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, + errno, "socket for SIOCETHTOOL(ETHTOOL_GET_TS_INFO)"); + return -1; + } + + memset(&ifr, 0, sizeof(ifr)); + pcap_strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); + memset(&info, 0, sizeof(info)); + info.cmd = ETHTOOL_GET_TS_INFO; + ifr.ifr_data = (caddr_t)&info; + if (ioctl(fd, SIOCETHTOOL, &ifr) == -1) { + int save_errno = errno; + + close(fd); + switch (save_errno) { + + case EOPNOTSUPP: + case EINVAL: + /* + * OK, this OS version or driver doesn't support + * asking for the time stamping types, so let's + * just return all the possible types. + */ + iface_set_all_ts_types(handle); + return 0; + + case ENODEV: + /* + * OK, no such device. + * The user will find that out when they try to + * activate the device; just return an empty + * list of time stamp types. + */ + handle->tstamp_type_list = NULL; + return 0; + + default: + /* + * Other error. + */ + pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, + save_errno, + "%s: SIOCETHTOOL(ETHTOOL_GET_TS_INFO) ioctl failed", + device); + return -1; + } + } + close(fd); + + /* + * Do we support hardware time stamping of *all* packets? + */ + if (!(info.rx_filters & (1 << HWTSTAMP_FILTER_ALL))) { + /* + * No, so don't report any time stamp types. + * + * XXX - some devices either don't report + * HWTSTAMP_FILTER_ALL when they do support it, or + * report HWTSTAMP_FILTER_ALL but map it to only + * time stamping a few PTP packets. See + * http://marc.info/?l=linux-netdev&m=146318183529571&w=2 + */ + handle->tstamp_type_list = NULL; + return 0; + } + + num_ts_types = 0; + for (i = 0; i < NUM_SOF_TIMESTAMPING_TYPES; i++) { + if (info.so_timestamping & sof_ts_type_map[i].soft_timestamping_val) + num_ts_types++; + } + handle->tstamp_type_count = num_ts_types; + if (num_ts_types != 0) { + handle->tstamp_type_list = malloc(num_ts_types * sizeof(u_int)); + for (i = 0, j = 0; i < NUM_SOF_TIMESTAMPING_TYPES; i++) { + if (info.so_timestamping & sof_ts_type_map[i].soft_timestamping_val) { + handle->tstamp_type_list[j] = sof_ts_type_map[i].pcap_tstamp_val; + j++; + } + } + } else + handle->tstamp_type_list = NULL; + + return 0; +} +#else /* ETHTOOL_GET_TS_INFO */ +static int +iface_ethtool_get_ts_info(const char *device, pcap_t *handle, char *ebuf _U_) +{ + /* + * This doesn't apply to the "any" device; you can't say "turn on + * hardware time stamping for all devices that exist now and arrange + * that it be turned on for any device that appears in the future", + * and not all devices even necessarily *support* hardware time + * stamping, so don't report any time stamp types. + */ + if (strcmp(device, "any") == 0) { + handle->tstamp_type_list = NULL; + return 0; + } + + /* + * We don't have an ioctl to use to ask what's supported, + * so say we support everything. + */ + iface_set_all_ts_types(handle); + return 0; +} +#endif /* ETHTOOL_GET_TS_INFO */ + +#endif /* defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) */ + +#ifdef HAVE_PACKET_RING +/* + * Find out if we have any form of fragmentation/reassembly offloading. + * + * We do so using SIOCETHTOOL checking for various types of offloading; + * if SIOCETHTOOL isn't defined, or we don't have any #defines for any + * of the types of offloading, there's nothing we can do to check, so + * we just say "no, we don't". + * + * We treat EOPNOTSUPP, EINVAL and, if eperm_ok is true, EPERM as + * indications that the operation isn't supported. We do EPERM + * weirdly because the SIOCETHTOOL code in later kernels 1) doesn't + * support ETHTOOL_GUFO, 2) also doesn't include it in the list + * of ethtool operations that don't require CAP_NET_ADMIN privileges, + * and 3) does the "is this permitted" check before doing the "is + * this even supported" check, so it fails with "this is not permitted" + * rather than "this is not even supported". To work around this + * annoyance, we only treat EPERM as an error for the first feature, + * and assume that they all do the same permission checks, so if the + * first one is allowed all the others are allowed if supported. + */ +#if defined(SIOCETHTOOL) && (defined(ETHTOOL_GTSO) || defined(ETHTOOL_GUFO) || defined(ETHTOOL_GGSO) || defined(ETHTOOL_GFLAGS) || defined(ETHTOOL_GGRO)) +static int +iface_ethtool_flag_ioctl(pcap_t *handle, int cmd, const char *cmdname, + int eperm_ok) +{ + struct ifreq ifr; + struct ethtool_value eval; + + memset(&ifr, 0, sizeof(ifr)); + pcap_strlcpy(ifr.ifr_name, handle->opt.device, sizeof(ifr.ifr_name)); + eval.cmd = cmd; + eval.data = 0; + ifr.ifr_data = (caddr_t)&eval; + if (ioctl(handle->fd, SIOCETHTOOL, &ifr) == -1) { + if (errno == EOPNOTSUPP || errno == EINVAL || + (errno == EPERM && eperm_ok)) { + /* + * OK, let's just return 0, which, in our + * case, either means "no, what we're asking + * about is not enabled" or "all the flags + * are clear (i.e., nothing is enabled)". + */ + return 0; + } + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "%s: SIOCETHTOOL(%s) ioctl failed", + handle->opt.device, cmdname); + return -1; + } + return eval.data; +} + +/* + * XXX - it's annoying that we have to check for offloading at all, but, + * given that we have to, it's still annoying that we have to check for + * particular types of offloading, especially that shiny new types of + * offloading may be added - and, worse, may not be checkable with + * a particular ETHTOOL_ operation; ETHTOOL_GFEATURES would, in + * theory, give those to you, but the actual flags being used are + * opaque (defined in a non-uapi header), and there doesn't seem to + * be any obvious way to ask the kernel what all the offloading flags + * are - at best, you can ask for a set of strings(!) to get *names* + * for various flags. (That whole mechanism appears to have been + * designed for the sole purpose of letting ethtool report flags + * by name and set flags by name, with the names having no semantics + * ethtool understands.) + */ +static int +iface_get_offload(pcap_t *handle) +{ + int ret; + +#ifdef ETHTOOL_GTSO + ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GTSO, "ETHTOOL_GTSO", 0); + if (ret == -1) + return -1; + if (ret) + return 1; /* TCP segmentation offloading on */ +#endif + +#ifdef ETHTOOL_GGSO + /* + * XXX - will this cause large unsegmented packets to be + * handed to PF_PACKET sockets on transmission? If not, + * this need not be checked. + */ + ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GGSO, "ETHTOOL_GGSO", 0); + if (ret == -1) + return -1; + if (ret) + return 1; /* generic segmentation offloading on */ +#endif + +#ifdef ETHTOOL_GFLAGS + ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GFLAGS, "ETHTOOL_GFLAGS", 0); + if (ret == -1) + return -1; + if (ret & ETH_FLAG_LRO) + return 1; /* large receive offloading on */ +#endif + +#ifdef ETHTOOL_GGRO + /* + * XXX - will this cause large reassembled packets to be + * handed to PF_PACKET sockets on receipt? If not, + * this need not be checked. + */ + ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GGRO, "ETHTOOL_GGRO", 0); + if (ret == -1) + return -1; + if (ret) + return 1; /* generic (large) receive offloading on */ +#endif + +#ifdef ETHTOOL_GUFO + /* + * Do this one last, as support for it was removed in later + * kernels, and it fails with EPERM on those kernels rather + * than with EOPNOTSUPP (see explanation in comment for + * iface_ethtool_flag_ioctl()). + */ + ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GUFO, "ETHTOOL_GUFO", 1); + if (ret == -1) + return -1; + if (ret) + return 1; /* UDP fragmentation offloading on */ +#endif + + return 0; +} +#else /* SIOCETHTOOL */ +static int +iface_get_offload(pcap_t *handle _U_) +{ + /* + * XXX - do we need to get this information if we don't + * have the ethtool ioctls? If so, how do we do that? + */ + return 0; +} +#endif /* SIOCETHTOOL */ + +#endif /* HAVE_PACKET_RING */ + +#endif /* HAVE_PF_PACKET_SOCKETS */ + +/* ===== Functions to interface to the older kernels ================== */ + +/* + * Try to open a packet socket using the old kernel interface. + * Returns 1 on success and a PCAP_ERROR_ value on an error. + */ +static int +activate_old(pcap_t *handle) +{ + struct pcap_linux *handlep = handle->priv; + int err; + int arptype; + struct ifreq ifr; + const char *device = handle->opt.device; + struct utsname utsname; + int mtu; + + /* + * PF_INET/SOCK_PACKET sockets must be bound to a device, so we + * can't support the "any" device. + */ + if (strcmp(device, "any") == 0) { + pcap_strlcpy(handle->errbuf, "pcap_activate: The \"any\" device isn't supported on 2.0[.x]-kernel systems", + PCAP_ERRBUF_SIZE); + return PCAP_ERROR; + } + + /* Open the socket */ + handle->fd = socket(PF_INET, SOCK_PACKET, htons(ETH_P_ALL)); + if (handle->fd == -1) { + err = errno; + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + err, "socket"); + if (err == EPERM || err == EACCES) { + /* + * You don't have permission to open the + * socket. + */ + return PCAP_ERROR_PERM_DENIED; + } else { + /* + * Other error. + */ + return PCAP_ERROR; + } + } + + /* It worked - we are using the old interface */ + handlep->sock_packet = 1; + + /* ...which means we get the link-layer header. */ + handlep->cooked = 0; + + /* Bind to the given device */ + if (iface_bind_old(handle->fd, device, handle->errbuf) == -1) + return PCAP_ERROR; + + /* + * Try to get the link-layer type. + */ + arptype = iface_get_arptype(handle->fd, device, handle->errbuf); + if (arptype < 0) + return PCAP_ERROR; + + /* + * Try to find the DLT_ type corresponding to that + * link-layer type. + */ + map_arphrd_to_dlt(handle, handle->fd, arptype, device, 0); + if (handle->linktype == -1) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "unknown arptype %d", arptype); + return PCAP_ERROR; + } + + /* Go to promisc mode if requested */ + + if (handle->opt.promisc) { + memset(&ifr, 0, sizeof(ifr)); + pcap_strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); + if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "SIOCGIFFLAGS"); + return PCAP_ERROR; + } + if ((ifr.ifr_flags & IFF_PROMISC) == 0) { + /* + * Promiscuous mode isn't currently on, + * so turn it on, and remember that + * we should turn it off when the + * pcap_t is closed. + */ + + /* + * If we haven't already done so, arrange + * to have "pcap_close_all()" called when + * we exit. + */ + if (!pcap_do_addexit(handle)) { + /* + * "atexit()" failed; don't put + * the interface in promiscuous + * mode, just give up. + */ + return PCAP_ERROR; + } + + ifr.ifr_flags |= IFF_PROMISC; + if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "SIOCSIFFLAGS"); + return PCAP_ERROR; + } + handlep->must_do_on_close |= MUST_CLEAR_PROMISC; + + /* + * Add this to the list of pcaps + * to close when we exit. + */ + pcap_add_to_pcaps_to_close(handle); + } + } + + /* + * Compute the buffer size. + * + * We're using SOCK_PACKET, so this might be a 2.0[.x] + * kernel, and might require special handling - check. + */ + if (uname(&utsname) < 0 || + strncmp(utsname.release, "2.0", 3) == 0) { + /* + * Either we couldn't find out what kernel release + * this is, or it's a 2.0[.x] kernel. + * + * In the 2.0[.x] kernel, a "recvfrom()" on + * a SOCK_PACKET socket, with MSG_TRUNC set, will + * return the number of bytes read, so if we pass + * a length based on the snapshot length, it'll + * return the number of bytes from the packet + * copied to userland, not the actual length + * of the packet. + * + * This means that, for example, the IP dissector + * in tcpdump will get handed a packet length less + * than the length in the IP header, and will + * complain about "truncated-ip". + * + * So we don't bother trying to copy from the + * kernel only the bytes in which we're interested, + * but instead copy them all, just as the older + * versions of libpcap for Linux did. + * + * The buffer therefore needs to be big enough to + * hold the largest packet we can get from this + * device. Unfortunately, we can't get the MRU + * of the network; we can only get the MTU. The + * MTU may be too small, in which case a packet larger + * than the buffer size will be truncated *and* we + * won't get the actual packet size. + * + * However, if the snapshot length is larger than + * the buffer size based on the MTU, we use the + * snapshot length as the buffer size, instead; + * this means that with a sufficiently large snapshot + * length we won't artificially truncate packets + * to the MTU-based size. + * + * This mess just one of many problems with packet + * capture on 2.0[.x] kernels; you really want a + * 2.2[.x] or later kernel if you want packet capture + * to work well. + */ + mtu = iface_get_mtu(handle->fd, device, handle->errbuf); + if (mtu == -1) + return PCAP_ERROR; + handle->bufsize = MAX_LINKHEADER_SIZE + mtu; + if (handle->bufsize < (u_int)handle->snapshot) + handle->bufsize = (u_int)handle->snapshot; + } else { + /* + * This is a 2.2[.x] or later kernel. + * + * We can safely pass "recvfrom()" a byte count + * based on the snapshot length. + * + * XXX - this "should not happen", as 2.2[.x] + * kernels all have PF_PACKET sockets, and there's + * no configuration option to disable them without + * disabling SOCK_PACKET sockets, because + * SOCK_PACKET sockets are implemented in the same + * source file, net/packet/af_packet.c. There *is* + * an option to disable SOCK_PACKET sockets so that + * you only have PF_PACKET sockets, and the kernel + * will log warning messages for code that uses + * "obsolete (PF_INET,SOCK_PACKET)". + */ + handle->bufsize = (u_int)handle->snapshot; + } + + /* + * Default value for offset to align link-layer payload + * on a 4-byte boundary. + */ + handle->offset = 0; + + /* + * SOCK_PACKET sockets don't supply information from + * stripped VLAN tags. + */ + handlep->vlan_offset = -1; /* unknown */ + + return 1; +} + +/* + * Bind the socket associated with FD to the given device using the + * interface of the old kernels. + */ +static int +iface_bind_old(int fd, const char *device, char *ebuf) +{ + struct sockaddr saddr; + int err; + socklen_t errlen = sizeof(err); + + memset(&saddr, 0, sizeof(saddr)); + pcap_strlcpy(saddr.sa_data, device, sizeof(saddr.sa_data)); + if (bind(fd, &saddr, sizeof(saddr)) == -1) { + pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, + errno, "bind"); + return -1; + } + + /* Any pending errors, e.g., network is down? */ + + if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) { + pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, + errno, "getsockopt (SO_ERROR)"); + return -1; + } + + if (err > 0) { + pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, + err, "bind"); + return -1; + } + + return 0; +} + + +/* ===== System calls available on all supported kernels ============== */ + +/* + * Query the kernel for the MTU of the given interface. + */ +static int +iface_get_mtu(int fd, const char *device, char *ebuf) +{ + struct ifreq ifr; + + if (!device) + return BIGGER_THAN_ALL_MTUS; + + memset(&ifr, 0, sizeof(ifr)); + pcap_strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); + + if (ioctl(fd, SIOCGIFMTU, &ifr) == -1) { + pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, + errno, "SIOCGIFMTU"); + return -1; + } + + return ifr.ifr_mtu; +} + +/* + * Get the hardware type of the given interface as ARPHRD_xxx constant. + */ +static int +iface_get_arptype(int fd, const char *device, char *ebuf) +{ + struct ifreq ifr; + int ret; + + memset(&ifr, 0, sizeof(ifr)); + pcap_strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); + + if (ioctl(fd, SIOCGIFHWADDR, &ifr) == -1) { + if (errno == ENODEV) { + /* + * No such device. + */ + ret = PCAP_ERROR_NO_SUCH_DEVICE; + } else + ret = PCAP_ERROR; + pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, + errno, "SIOCGIFHWADDR"); + return ret; + } + + return ifr.ifr_hwaddr.sa_family; +} + +#ifdef SO_ATTACH_FILTER +static int +fix_program(pcap_t *handle, struct sock_fprog *fcode, int is_mmapped) +{ + struct pcap_linux *handlep = handle->priv; + size_t prog_size; + register int i; + register struct bpf_insn *p; + struct bpf_insn *f; + int len; + + /* + * Make a copy of the filter, and modify that copy if + * necessary. + */ + prog_size = sizeof(*handle->fcode.bf_insns) * handle->fcode.bf_len; + len = handle->fcode.bf_len; + f = (struct bpf_insn *)malloc(prog_size); + if (f == NULL) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "malloc"); + return -1; + } + memcpy(f, handle->fcode.bf_insns, prog_size); + fcode->len = len; + fcode->filter = (struct sock_filter *) f; + + for (i = 0; i < len; ++i) { + p = &f[i]; + /* + * What type of instruction is this? + */ + switch (BPF_CLASS(p->code)) { + + case BPF_RET: + /* + * It's a return instruction; are we capturing + * in memory-mapped mode? + */ + if (!is_mmapped) { + /* + * No; is the snapshot length a constant, + * rather than the contents of the + * accumulator? + */ + if (BPF_MODE(p->code) == BPF_K) { + /* + * Yes - if the value to be returned, + * i.e. the snapshot length, is + * anything other than 0, make it + * MAXIMUM_SNAPLEN, so that the packet + * is truncated by "recvfrom()", + * not by the filter. + * + * XXX - there's nothing we can + * easily do if it's getting the + * value from the accumulator; we'd + * have to insert code to force + * non-zero values to be + * MAXIMUM_SNAPLEN. + */ + if (p->k != 0) + p->k = MAXIMUM_SNAPLEN; + } + } + break; + + case BPF_LD: + case BPF_LDX: + /* + * It's a load instruction; is it loading + * from the packet? + */ + switch (BPF_MODE(p->code)) { + + case BPF_ABS: + case BPF_IND: + case BPF_MSH: + /* + * Yes; are we in cooked mode? + */ + if (handlep->cooked) { + /* + * Yes, so we need to fix this + * instruction. + */ + if (fix_offset(handle, p) < 0) { + /* + * We failed to do so. + * Return 0, so our caller + * knows to punt to userland. + */ + return 0; + } + } + break; + } + break; + } + } + return 1; /* we succeeded */ +} + +static int +fix_offset(pcap_t *handle, struct bpf_insn *p) +{ + /* + * Existing references to auxiliary data shouldn't be adjusted. + * + * Note that SKF_AD_OFF is negative, but p->k is unsigned, so + * we use >= and cast SKF_AD_OFF to unsigned. + */ + if (p->k >= (bpf_u_int32)SKF_AD_OFF) + return 0; + if (handle->linktype == DLT_LINUX_SLL2) { + /* + * What's the offset? + */ + if (p->k >= SLL2_HDR_LEN) { + /* + * It's within the link-layer payload; that starts + * at an offset of 0, as far as the kernel packet + * filter is concerned, so subtract the length of + * the link-layer header. + */ + p->k -= SLL2_HDR_LEN; + } else if (p->k == 0) { + /* + * It's the protocol field; map it to the + * special magic kernel offset for that field. + */ + p->k = SKF_AD_OFF + SKF_AD_PROTOCOL; + } else if (p->k == 10) { + /* + * It's the packet type field; map it to the + * special magic kernel offset for that field. + */ + p->k = SKF_AD_OFF + SKF_AD_PKTTYPE; + } else if ((bpf_int32)(p->k) > 0) { + /* + * It's within the header, but it's not one of + * those fields; we can't do that in the kernel, + * so punt to userland. + */ + return -1; + } + } else { + /* + * What's the offset? + */ + if (p->k >= SLL_HDR_LEN) { + /* + * It's within the link-layer payload; that starts + * at an offset of 0, as far as the kernel packet + * filter is concerned, so subtract the length of + * the link-layer header. + */ + p->k -= SLL_HDR_LEN; + } else if (p->k == 0) { + /* + * It's the packet type field; map it to the + * special magic kernel offset for that field. + */ + p->k = SKF_AD_OFF + SKF_AD_PKTTYPE; + } else if (p->k == 14) { + /* + * It's the protocol field; map it to the + * special magic kernel offset for that field. + */ + p->k = SKF_AD_OFF + SKF_AD_PROTOCOL; + } else if ((bpf_int32)(p->k) > 0) { + /* + * It's within the header, but it's not one of + * those fields; we can't do that in the kernel, + * so punt to userland. + */ + return -1; + } + } + return 0; +} + +static int +set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode) +{ + int total_filter_on = 0; + int save_mode; + int ret; + int save_errno; + + /* + * The socket filter code doesn't discard all packets queued + * up on the socket when the filter is changed; this means + * that packets that don't match the new filter may show up + * after the new filter is put onto the socket, if those + * packets haven't yet been read. + * + * This means, for example, that if you do a tcpdump capture + * with a filter, the first few packets in the capture might + * be packets that wouldn't have passed the filter. + * + * We therefore discard all packets queued up on the socket + * when setting a kernel filter. (This isn't an issue for + * userland filters, as the userland filtering is done after + * packets are queued up.) + * + * To flush those packets, we put the socket in read-only mode, + * and read packets from the socket until there are no more to + * read. + * + * In order to keep that from being an infinite loop - i.e., + * to keep more packets from arriving while we're draining + * the queue - we put the "total filter", which is a filter + * that rejects all packets, onto the socket before draining + * the queue. + * + * This code deliberately ignores any errors, so that you may + * get bogus packets if an error occurs, rather than having + * the filtering done in userland even if it could have been + * done in the kernel. + */ + if (setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER, + &total_fcode, sizeof(total_fcode)) == 0) { + char drain[1]; + + /* + * Note that we've put the total filter onto the socket. + */ + total_filter_on = 1; + + /* + * Save the socket's current mode, and put it in + * non-blocking mode; we drain it by reading packets + * until we get an error (which is normally a + * "nothing more to be read" error). + */ + save_mode = fcntl(handle->fd, F_GETFL, 0); + if (save_mode == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "can't get FD flags when changing filter"); + return -2; + } + if (fcntl(handle->fd, F_SETFL, save_mode | O_NONBLOCK) < 0) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "can't set nonblocking mode when changing filter"); + return -2; + } + while (recv(handle->fd, &drain, sizeof drain, MSG_TRUNC) >= 0) + ; + save_errno = errno; + if (save_errno != EAGAIN) { + /* + * Fatal error. + * + * If we can't restore the mode or reset the + * kernel filter, there's nothing we can do. + */ + (void)fcntl(handle->fd, F_SETFL, save_mode); + (void)reset_kernel_filter(handle); + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, save_errno, + "recv failed when changing filter"); + return -2; + } + if (fcntl(handle->fd, F_SETFL, save_mode) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "can't restore FD flags when changing filter"); + return -2; + } + } + + /* + * Now attach the new filter. + */ + ret = setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER, + fcode, sizeof(*fcode)); + if (ret == -1 && total_filter_on) { + /* + * Well, we couldn't set that filter on the socket, + * but we could set the total filter on the socket. + * + * This could, for example, mean that the filter was + * too big to put into the kernel, so we'll have to + * filter in userland; in any case, we'll be doing + * filtering in userland, so we need to remove the + * total filter so we see packets. + */ + save_errno = errno; + + /* + * If this fails, we're really screwed; we have the + * total filter on the socket, and it won't come off. + * Report it as a fatal error. + */ + if (reset_kernel_filter(handle) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "can't remove kernel total filter"); + return -2; /* fatal error */ + } + + errno = save_errno; + } + return ret; +} + +static int +reset_kernel_filter(pcap_t *handle) +{ + int ret; + /* + * setsockopt() barfs unless it get a dummy parameter. + * valgrind whines unless the value is initialized, + * as it has no idea that setsockopt() ignores its + * parameter. + */ + int dummy = 0; + + ret = setsockopt(handle->fd, SOL_SOCKET, SO_DETACH_FILTER, + &dummy, sizeof(dummy)); + /* + * Ignore ENOENT - it means "we don't have a filter", so there + * was no filter to remove, and there's still no filter. + * + * Also ignore ENONET, as a lot of kernel versions had a + * typo where ENONET, rather than ENOENT, was returned. + */ + if (ret == -1 && errno != ENOENT && errno != ENONET) + return -1; + return 0; +} +#endif + +int +pcap_set_protocol_linux(pcap_t *p, int protocol) +{ + if (pcap_check_activated(p)) + return (PCAP_ERROR_ACTIVATED); + p->opt.protocol = protocol; + return (0); +} + +/* + * Libpcap version string. + */ +const char * +pcap_lib_version(void) +{ +#ifdef HAVE_PACKET_RING + #if defined(HAVE_TPACKET3) + return (PCAP_VERSION_STRING " (with TPACKET_V3)"); + #elif defined(HAVE_TPACKET2) + return (PCAP_VERSION_STRING " (with TPACKET_V2)"); + #else + return (PCAP_VERSION_STRING " (with TPACKET_V1)"); + #endif +#else + return (PCAP_VERSION_STRING " (without TPACKET)"); +#endif +} |