contrib/sendmail-8.14/test/t_setuid.c

   1 /*
   2  * Copyright (c) 2001 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 checks to see if your version of setuid works.
  13 **  Compile it, make it set-user-ID root, and run it as yourself (NOT as
  14 **  root).
  15 **
  16 **      NOTE:  This should work everywhere, but Linux has the ability
  17 **      to use the undocumented setcap() call to make this break.
  18 **
  19 **  Compilation is trivial -- just "cc t_setuid.c".  Make it set-user-ID,
  20 **  root and then execute it as a non-root user.
  21 */
  22
  23 #include <sys/types.h>
  24 #include <unistd.h>
  25 #include <stdio.h>
  26
  27 #ifndef lint
  28 static char id[] = "@(#)$Id: t_setuid.c,v 8.7 2001/09/23 03:35:41 ca Exp $";
  29 #endif /* ! lint */
  30
  31 static void
  32 printuids(str, r, e)
  33         char *str;
  34         uid_t r, e;
  35 {
  36         printf("%s (should be %d/%d): r/euid=%d/%d\n", str, (int) r, (int) e,
  37                (int) getuid(), (int) geteuid());
  38 }
  39
  40 int
  41 main(argc, argv)
  42         int argc;
  43         char **argv;
  44 {
  45         int fail = 0;
  46         uid_t realuid = getuid();
  47
  48         printuids("initial uids", realuid, 0);
  49
  50         if (geteuid() != 0)
  51         {
  52                 printf("SETUP ERROR: re-run set-user-ID root\n");
  53                 exit(1);
  54         }
  55
  56         if (getuid() == 0)
  57         {
  58                 printf("SETUP ERROR: must be run by a non-root user\n");
  59                 exit(1);
  60         }
  61
  62         if (setuid(1) < 0)
  63                 printf("setuid(1) failure\n");
  64         printuids("after setuid(1)", 1, 1);
  65
  66         if (geteuid() != 1)
  67         {
  68                 fail++;
  69                 printf("MAYDAY!  Wrong effective uid\n");
  70         }
  71
  72         if (getuid() != 1)
  73         {
  74                 fail++;
  75                 printf("MAYDAY!  Wrong real uid\n");
  76         }
  77
  78
  79         /* do activity here */
  80         if (setuid(0) == 0)
  81         {
  82                 fail++;
  83                 printf("MAYDAY!  setuid(0) succeeded (should have failed)\n");
  84         }
  85         else
  86         {
  87                 printf("setuid(0) failed (this is correct)\n");
  88         }
  89         printuids("after setuid(0)", 1, 1);
  90
  91         if (geteuid() != 1)
  92         {
  93                 fail++;
  94                 printf("MAYDAY!  Wrong effective uid\n");
  95         }
  96         if (getuid() != 1)
  97         {
  98                 fail++;
  99                 printf("MAYDAY!  Wrong real uid\n");
 100         }
 101         printf("\n");
 102
 103         if (fail)
 104         {
 105                 printf("\nThis system cannot use setuid (maybe use setreuid)\n");
 106                 exit(1);
 107         }
 108
 109         printf("\nIt is safe to use setuid on this system\n");
 110         exit(0);
 111 }