libutil/_secure_path.c

   1 /*-
   2  * Based on code copyright (c) 1995,1997 by
   3  * Berkeley Software Design, Inc.
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, is permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice immediately at the beginning of the file, without modification,
  11  *    this list of conditions, and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. This work was done expressly for inclusion into FreeBSD.  Other use
  16  *    is permitted provided this notation is included.
  17  * 4. Absolutely no warranty of function or purpose is made by the authors.
  18  * 5. Modifications may be freely made to this file providing the above
  19  *    conditions are met.
  20  */
  21
  22 #include <sys/cdefs.h>
  23 __FBSDID("$FreeBSD$");
  24
  25 #include <sys/types.h>
  26 #include <sys/stat.h>
  27
  28 #include <errno.h>
  29 #include <libutil.h>
  30 #include <stddef.h>
  31 #include <syslog.h>
  32
  33 /*
  34  * Check for common security problems on a given path
  35  * It must be:
  36  * 1. A regular file, and exists
  37  * 2. Owned and writable only by root (or given owner)
  38  * 3. Group ownership is given group or is non-group writable
  39  *
  40  * Returns:     -2 if file does not exist,
  41  *              -1 if security test failure
  42  *              0  otherwise
  43  */
  44
  45 int
  46 _secure_path(const char *path, uid_t uid, gid_t gid)
  47 {
  48     int         r = -1;
  49     struct stat sb;
  50     const char  *msg = NULL;
  51
  52     if (lstat(path, &sb) < 0) {
  53         if (errno == ENOENT) /* special case */
  54             r = -2;  /* if it is just missing, skip the log entry */
  55         else
  56             msg = "%s: cannot stat %s: %m";
  57     }
  58     else if (!S_ISREG(sb.st_mode))
  59         msg = "%s: %s is not a regular file";
  60     else if (sb.st_mode & S_IWOTH)
  61         msg = "%s: %s is world writable";
  62     else if ((int)uid != -1 && sb.st_uid != uid && sb.st_uid != 0) {
  63         if (uid == 0)
  64                 msg = "%s: %s is not owned by root";
  65         else
  66                 msg = "%s: %s is not owned by uid %d";
  67     } else if ((int)gid != -1 && sb.st_gid != gid && (sb.st_mode & S_IWGRP))
  68         msg = "%s: %s is group writeable by non-authorised groups";
  69     else
  70         r = 0;
  71     if (msg != NULL)
  72         syslog(LOG_ERR, msg, "_secure_path", path, uid);
  73     return r;
  74 }