src/src/lookups/lf_check_file.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) University of Cambridge 1995 - 2009 */
   6 /* See the file NOTICE for conditions of use and distribution. */
   7
   8
   9 #include "../exim.h"
  10 #include "lf_functions.h"
  11
  12
  13
  14 /*************************************************
  15 *         Check a file's credentials             *
  16 *************************************************/
  17
  18 /* fstat can normally be expected to work on an open file, but there are some
  19 NFS states where it may not.
  20
  21 Arguments:
  22   fd         an open file descriptor or -1
  23   filename   a file name if fd is -1
  24   s_type     type of file (S_IFREG or S_IFDIR)
  25   modemask   a mask specifying mode bits that must *not* be set
  26   owners     NULL or a list of of allowable uids, count in the first item
  27   owngroups  NULL or a list of allowable gids, count in the first item
  28   type       name of lookup type for putting in error message
  29   errmsg     where to put an error message
  30
  31 Returns:     -1 stat() or fstat() failed
  32               0 OK
  33              +1 something didn't match
  34
  35 Side effect: sets errno to ERRNO_BADUGID, ERRNO_NOTREGULAR or ERRNO_BADMODE for
  36              bad uid/gid, not a regular file, or bad mode; otherwise leaves it
  37              to what fstat set it to.
  38 */
  39
  40 int
  41 lf_check_file(int fd, uschar *filename, int s_type, int modemask, uid_t *owners,
  42   gid_t *owngroups, const char *type, uschar **errmsg)
  43 {
  44 struct stat statbuf;
  45
  46 if ((fd >= 0 && fstat(fd, &statbuf) != 0) ||
  47     (fd  < 0 && Ustat(filename, &statbuf) != 0))
  48   {
  49   int save_errno = errno;
  50   *errmsg = string_sprintf("%s: stat failed", filename);
  51   errno = save_errno;
  52   return -1;
  53   }
  54
  55 if ((statbuf.st_mode & S_IFMT) != s_type)
  56   {
  57   if (s_type == S_IFREG)
  58     {
  59     *errmsg = string_sprintf("%s is not a regular file (%s lookup)",
  60       filename, type);
  61     errno = ERRNO_NOTREGULAR;
  62     }
  63   else
  64     {
  65     *errmsg = string_sprintf("%s is not a directory (%s lookup)",
  66       filename, type);
  67     errno = ERRNO_NOTDIRECTORY;
  68     }
  69   return +1;
  70   }
  71
  72 if ((statbuf.st_mode & modemask) != 0)
  73   {
  74   *errmsg = string_sprintf("%s (%s lookup): file mode %.4o should not contain "
  75     "%.4o", filename, type,  statbuf.st_mode & 07777,
  76     statbuf.st_mode & modemask);
  77   errno = ERRNO_BADMODE;
  78   return +1;
  79   }
  80
  81 if (owners != NULL)
  82   {
  83   BOOL uid_ok = FALSE;
  84   for (int i = 1; i <= (int)owners[0]; i++)
  85     if (owners[i] == statbuf.st_uid) { uid_ok = TRUE; break; }
  86   if (!uid_ok)
  87     {
  88     *errmsg = string_sprintf("%s (%s lookup): file has wrong owner", filename,
  89       type);
  90     errno = ERRNO_BADUGID;
  91     return +1;
  92     }
  93   }
  94
  95 if (owngroups != NULL)
  96   {
  97   BOOL gid_ok = FALSE;
  98   for (int i = 1; i <= (int)owngroups[0]; i++)
  99     if (owngroups[i] == statbuf.st_gid) { gid_ok = TRUE; break; }
 100   if (!gid_ok)
 101     {
 102     *errmsg = string_sprintf("%s (%s lookup): file has wrong group", filename,
 103       type);
 104     errno = ERRNO_BADUGID;
 105     return +1;
 106     }
 107   }
 108
 109 return 0;
 110 }
 111
 112 /* End of lf_check_file.c */