contrib/sendmail/test/t_exclopen.c

   1 /*
   2  * Copyright (c) 1999 Sendmail, Inc. and its suppliers.
   3  *      All rights reserved.
   4  *
   5  * By using this file, you agree to the terms and conditions set
   6  * forth in the LICENSE file which can be found at the top level of
   7  * the sendmail distribution.
   8  *
   9  */
  10
  11 /*
  12 **  This program tests your system to see if you have the lovely
  13 **  security-defeating semantics that an open with O_CREAT|O_EXCL
  14 **  set will successfully open a file named by a symbolic link that
  15 **  points to a non-existent file.  Sadly, Posix is mute on what
  16 **  should happen in this situation.
  17 **
  18 **  Results to date:
  19 **      AIX 3.2         OK
  20 **      BSD family      OK
  21 **        BSD/OS 2.1    OK
  22 **        FreeBSD 2.1   OK
  23 **      DEC OSF/1 3.0   OK
  24 **      HP-UX 9.04      FAIL
  25 **      HP-UX 9.05      FAIL
  26 **      HP-UX 9.07      OK
  27 **      HP-UX 10.01     OK
  28 **      HP-UX 10.10     OK
  29 **      HP-UX 10.20     OK
  30 **      Irix 5.3        OK
  31 **      Irix 6.2        OK
  32 **      Irix 6.3        OK
  33 **      Irix 6.4        OK
  34 **      Linux           OK
  35 **      NeXT 2.1        OK
  36 **      Solaris 2.x     OK
  37 **      SunOS 4.x       OK
  38 **      Ultrix 4.3      OK
  39 */
  40
  41 #include <sys/types.h>
  42 #include <sys/stat.h>
  43 #include <errno.h>
  44 #include <fcntl.h>
  45 #include <stdio.h>
  46 #include <unistd.h>
  47
  48 #ifndef lint
  49 static char id[] = "@(#)$Id: t_exclopen.c,v 8.6 2001/09/23 03:35:41 ca Exp $";
  50 #endif /* ! lint */
  51
  52 static char Attacker[128];
  53 static char Attackee[128];
  54
  55 static void
  56 bail(status)
  57         int status;
  58 {
  59         (void) unlink(Attacker);
  60         (void) unlink(Attackee);
  61         exit(status);
  62 }
  63
  64 int
  65 main(argc, argv)
  66         int argc;
  67         char **argv;
  68 {
  69         struct stat st;
  70
  71         sprintf(Attacker, "/tmp/attacker.%d.%ld", getpid(), time(NULL));
  72         sprintf(Attackee, "/tmp/attackee.%d.%ld", getpid(), time(NULL));
  73
  74         if (symlink(Attackee, Attacker) < 0)
  75         {
  76                 printf("Could not create %s->%s symlink: %d\n",
  77                         Attacker, Attackee, errno);
  78                 bail(1);
  79         }
  80         (void) unlink(Attackee);
  81         if (stat(Attackee, &st) >= 0)
  82         {
  83                 printf("%s already exists -- remove and try again.\n",
  84                         Attackee);
  85                 bail(1);
  86         }
  87         if (open(Attacker, O_WRONLY|O_CREAT|O_EXCL, 0644) < 0)
  88         {
  89                 int save_errno = errno;
  90
  91                 if (stat(Attackee, &st) >= 0)
  92                 {
  93                         printf("Weird.  Open failed but %s was created anyhow (errno = %d)\n",
  94                                 Attackee, save_errno);
  95                         bail(1);
  96                 }
  97                 printf("Good show!  Exclusive open works properly with symbolic links (errno = %d).\n",
  98                         save_errno);
  99                 bail(0);
 100         }
 101         if (stat(Attackee, &st) < 0)
 102         {
 103                 printf("Weird.  Open succeeded but %s was not created\n",
 104                         Attackee);
 105                 bail(2);
 106         }
 107         printf("Bad news: you can do an exclusive open through a symbolic link\n");
 108         printf("\tBe sure you #define BOGUS_O_EXCL in conf.h\n");
 109         bail(1);
 110
 111         /* NOTREACHED */
 112         exit(0);
 113 }