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-rw-r--r--system_cmds/gcore.tproj/dyld.c314
1 files changed, 314 insertions, 0 deletions
diff --git a/system_cmds/gcore.tproj/dyld.c b/system_cmds/gcore.tproj/dyld.c
new file mode 100644
index 0000000..92aeac1
--- /dev/null
+++ b/system_cmds/gcore.tproj/dyld.c
@@ -0,0 +1,314 @@
+/*
+ * Copyright (c) 2016 Apple Inc. All rights reserved.
+ */
+
+#include "options.h"
+#include "dyld.h"
+#include "utils.h"
+#include "corefile.h"
+#include "vm.h"
+
+#include <mach-o/loader.h>
+#include <mach-o/fat.h>
+#include <mach-o/dyld_process_info.h>
+
+#include <mach/mach.h>
+#include <mach/task.h>
+#include <mach/mach_vm.h>
+#include <mach/shared_region.h>
+#include <sys/param.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <time.h>
+#include <libgen.h>
+#include <sys/stat.h>
+
+/*
+ * WARNING WARNING WARNING
+ *
+ * Do not trust any of the data from the target task.
+ *
+ * A broken program may have damaged it, or a malicious
+ * program may have deliberately constructed something to
+ * cause us harm.
+ */
+
+static const char warn_dyld_info[] = "dyld information is incomplete or damaged";
+
+dyld_process_info
+get_task_dyld_info(const task_t task)
+{
+ kern_return_t kret;
+ dyld_process_info dpi = _dyld_process_info_create(task, 0, &kret);
+ if (NULL == dpi) {
+ err_mach(kret, NULL, "_dlyd_process_info_create");
+ } else {
+ dyld_process_state_info stateInfo;
+
+ _dyld_process_info_get_state(dpi, &stateInfo);
+ switch (stateInfo.dyldState) {
+ case dyld_process_state_not_started:
+ warnx("%s: dyld state %d", warn_dyld_info, stateInfo.dyldState);
+ _dyld_process_info_release(dpi);
+ dpi = NULL;
+ break;
+ default:
+ break;
+ }
+ }
+ return dpi;
+}
+
+/*
+ * Get the shared cache UUID iff it's in use and is the system one
+ */
+bool
+get_sc_uuid(dyld_process_info dpi, uuid_t uu)
+{
+ dyld_process_cache_info cacheInfo;
+
+ _dyld_process_info_get_cache(dpi, &cacheInfo);
+ if (!cacheInfo.noCache && !cacheInfo.privateCache) {
+ uuid_copy(uu, cacheInfo.cacheUUID);
+ return true;
+ }
+ return false;
+}
+
+void
+free_task_dyld_info(dyld_process_info dpi)
+{
+ _dyld_process_info_release(dpi);
+}
+
+/*
+ * This routine collects both the Mach-O header and the commands
+ * "below" it, assuming they're in contiguous memory.
+ */
+static native_mach_header_t *
+copy_dyld_image_mh(task_t task, mach_vm_address_t targetmh, const char *path)
+{
+ vm_offset_t mhaddr = 0;
+ mach_msg_type_number_t mhlen = sizeof (native_mach_header_t);
+
+ for (int attempts = 0; attempts < 2; attempts++) {
+
+ const kern_return_t ret = mach_vm_read(task, targetmh, mhlen, &mhaddr, &mhlen);
+ if (KERN_SUCCESS != ret) {
+ err_mach(ret, NULL, "mach_vm_read() at 0x%llx for image %s\n", targetmh, path);
+ mhaddr = 0;
+ break;
+ }
+ const native_mach_header_t *mh = (void *)mhaddr;
+ if (mhlen < mh->sizeofcmds + sizeof (*mh)) {
+ const mach_msg_type_number_t newmhlen = sizeof (*mh) + mh->sizeofcmds;
+ mach_vm_deallocate(mach_task_self(), mhaddr, mhlen);
+ mhlen = newmhlen;
+ } else
+ break;
+ }
+
+ native_mach_header_t *result = NULL;
+
+ if (mhaddr) {
+ if (NULL != (result = malloc(mhlen)))
+ memcpy(result, (void *)mhaddr, mhlen);
+ mach_vm_deallocate(mach_task_self(), mhaddr, mhlen);
+ }
+ return result;
+}
+
+/*
+ * This table (list) describes libraries and the executable in the address space
+ */
+struct liblist {
+ STAILQ_ENTRY(liblist) ll_linkage;
+ unsigned long ll_namehash;
+ struct libent ll_entry;
+};
+static STAILQ_HEAD(, liblist) libhead = STAILQ_HEAD_INITIALIZER(libhead);
+
+static const struct libent *
+libent_lookup_bypathname_withhash(const char *nm, const unsigned long hash)
+{
+ struct liblist *ll;
+ STAILQ_FOREACH(ll, &libhead, ll_linkage) {
+ if (hash != ll->ll_namehash)
+ continue;
+ struct libent *le = &ll->ll_entry;
+ if (strcmp(nm, le->le_pathname) == 0)
+ return le;
+ }
+ return NULL;
+}
+
+const struct libent *
+libent_lookup_byuuid(const uuid_t uuid)
+{
+ struct liblist *ll;
+ STAILQ_FOREACH(ll, &libhead, ll_linkage) {
+ struct libent *le = &ll->ll_entry;
+ if (uuid_compare(uuid, le->le_uuid) == 0)
+ return le;
+ }
+ return NULL;
+}
+
+const struct libent *
+libent_lookup_first_bytype(uint32_t mhtype)
+{
+ struct liblist *ll;
+ STAILQ_FOREACH(ll, &libhead, ll_linkage) {
+ struct libent *le = &ll->ll_entry;
+ if (mhtype == le->le_mh->filetype)
+ return le;
+ }
+ return NULL;
+}
+
+const struct libent *
+libent_insert(const char *rawnm, const uuid_t uuid, uint64_t mhaddr, const native_mach_header_t *mh, const struct vm_range *vr, mach_vm_offset_t objoff)
+{
+ const struct libent *le = libent_lookup_byuuid(uuid);
+ if (NULL != le)
+ return le; // disallow multiple names for the same uuid
+
+ char *nm = realpath(rawnm, NULL);
+ if (NULL == nm)
+ nm = strdup(rawnm);
+ const unsigned long nmhash = simple_namehash(nm);
+ le = libent_lookup_bypathname_withhash(nm, nmhash);
+ if (NULL != le) {
+ free(nm);
+ return le;
+ }
+
+ if (OPTIONS_DEBUG(opt, 3)) {
+ uuid_string_t uustr;
+ uuid_unparse_lower(uuid, uustr);
+ printf("[adding <'%s', %s, 0x%llx, %p", nm, uustr, mhaddr, mh);
+ if (vr)
+ printf(" (%llx-%llx)", V_ADDR(vr), V_ENDADDR(vr));
+ printf(">]\n");
+ }
+ struct liblist *ll = malloc(sizeof (*ll));
+ ll->ll_namehash = nmhash;
+ ll->ll_entry.le_pathname = nm;
+ ll->ll_entry.le_filename = strrchr(ll->ll_entry.le_pathname, '/');
+ if (NULL == ll->ll_entry.le_filename)
+ ll->ll_entry.le_filename = ll->ll_entry.le_pathname;
+ else
+ ll->ll_entry.le_filename++;
+ uuid_copy(ll->ll_entry.le_uuid, uuid);
+ ll->ll_entry.le_mhaddr = mhaddr;
+ ll->ll_entry.le_mh = mh;
+ if (vr)
+ ll->ll_entry.le_vr = *vr;
+ else {
+ V_SETADDR(&ll->ll_entry.le_vr, MACH_VM_MAX_ADDRESS);
+ V_SETSIZE(&ll->ll_entry.le_vr, 0);
+ }
+ ll->ll_entry.le_objoff = objoff;
+ STAILQ_INSERT_HEAD(&libhead, ll, ll_linkage);
+
+ return &ll->ll_entry;
+}
+
+bool
+libent_build_nametable(task_t task, dyld_process_info dpi)
+{
+ __block bool valid = true;
+
+ _dyld_process_info_for_each_image(dpi, ^(uint64_t mhaddr, const uuid_t uuid, const char *path) {
+ if (valid) {
+ native_mach_header_t *mh = copy_dyld_image_mh(task, mhaddr, path);
+ if (mh) {
+ /*
+ * Validate the rest of the mach information in the header before attempting optimizations
+ */
+ const size_t mhlen = sizeof (*mh) + mh->sizeofcmds;
+ const struct load_command *lc = (const void *)(mh + 1);
+ struct vm_range vr = {
+ .addr = MACH_VM_MAX_ADDRESS,
+ .size = 0
+ };
+ mach_vm_offset_t objoff = MACH_VM_MAX_ADDRESS;
+
+ for (unsigned n = 0; n < mh->ncmds; n++) {
+ if (((uintptr_t)lc & 0x3) != 0 ||
+ (uintptr_t)lc < (uintptr_t)mh || (uintptr_t)lc > (uintptr_t)mh + mhlen) {
+ warnx("%s, %d", warn_dyld_info, __LINE__);
+ valid = false;
+ break;
+ }
+ switch (lc->cmd) {
+ case NATIVE_LC_SEGMENT: {
+ const native_segment_command_t *sc = (const void *)lc;
+
+ char scsegname[17];
+ strlcpy(scsegname, sc->segname, sizeof (scsegname));
+
+ if (0 == sc->vmaddr &&
+ strcmp(scsegname, SEG_PAGEZERO) == 0)
+ break;
+
+ /*
+ * -Depends- on finding a __TEXT segment first
+ * which implicitly maps the mach header too
+ */
+
+ if (MACH_VM_MAX_ADDRESS == objoff) {
+ if (strcmp(scsegname, SEG_TEXT) == 0) {
+ objoff = mhaddr - sc->vmaddr;
+ V_SETADDR(&vr, mhaddr);
+ V_SETSIZE(&vr, sc->vmsize);
+ } else {
+ printf("%s: expected %s segment, found %s\n", path, SEG_TEXT, scsegname);
+ valid = false;
+ break;
+ }
+ }
+
+ mach_vm_offset_t lo = sc->vmaddr + objoff;
+ mach_vm_offset_t hi = lo + sc->vmsize;
+
+ if (V_SIZE(&vr)) {
+ if (lo < V_ADDR(&vr)) {
+ mach_vm_offset_t newsize = V_SIZE(&vr) + (V_ADDR(&vr) - lo);
+ V_SETSIZE(&vr, newsize);
+ V_SETADDR(&vr, lo);
+ }
+ if (hi > V_ENDADDR(&vr)) {
+ V_SETSIZE(&vr, (hi - V_ADDR(&vr)));
+ }
+ } else {
+ V_SETADDR(&vr, lo);
+ V_SETSIZE(&vr, hi - lo);
+ }
+ assert(lo >= V_ADDR(&vr) && hi <= V_ENDADDR(&vr));
+ } break;
+#if defined(RDAR_28040018)
+ case LC_ID_DYLINKER:
+ if (MH_DYLINKER == mh->filetype) {
+ /* workaround: the API doesn't always return the right name */
+ const struct dylinker_command *dc = (const void *)lc;
+ path = dc->name.offset + (const char *)dc;
+ }
+ break;
+#endif
+ default:
+ break;
+ }
+ if (NULL == (lc = next_lc(lc)))
+ break;
+ }
+ if (valid)
+ (void) libent_insert(path, uuid, mhaddr, mh, &vr, objoff);
+ }
+ }
+ });
+ if (OPTIONS_DEBUG(opt, 3))
+ printf("nametable %sconstructed\n", valid ? "" : "NOT ");
+ return valid;
+}
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