src/setuidgid.c

   1 /* setuidgid - run a command with the UID and GID of a specified user
   2    Copyright (C) 2003, 2004 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Written by Jim Meyering  */
  19
  20 #include <config.h>
  21 #include <stdio.h>
  22 #include <sys/types.h>
  23 #include <pwd.h>
  24 #include <grp.h>
  25
  26 #include "system.h"
  27
  28 #include "error.h"
  29 #include "long-options.h"
  30 #include "quote.h"
  31
  32 #define PROGRAM_NAME "setuidgid"
  33
  34 /* I wrote this program from scratch, based on the description of
  35    D.J. Bernstein's program: http://cr.yp.to/daemontools/setuidgid.html.  */
  36 #define AUTHORS "Jim Meyering"
  37
  38 #define SETUIDGID_FAILURE 111
  39
  40 char *program_name;
  41
  42 void
  43 usage (int status)
  44 {
  45   if (status != EXIT_SUCCESS)
  46     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  47              program_name);
  48   else
  49     {
  50       printf (_("\
  51 Usage: %s USERNAME COMMAND [ARGUMENT]...\n\
  52   or:  %s OPTION\n\
  53 "),
  54               program_name, program_name);
  55
  56       fputs (_("\
  57 Drop any supplemental groups, assume the user-ID and group-ID of\n\
  58 the specified USERNAME, and run COMMAND with any specified ARGUMENTs.\n\
  59 Exit with status 111 if unable to assume the required UID and GID.\n\
  60 Otherwise, exit with the exit status of COMMAND.\n\
  61 This program is useful only when run by root (UID=0).\n\
  62 \n\
  63 "), stdout);
  64       fputs (HELP_OPTION_DESCRIPTION, stdout);
  65       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  66       printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
  67     }
  68   exit (status);
  69 }
  70
  71 int
  72 main (int argc, char **argv)
  73 {
  74   char const *user_id;
  75   struct passwd *pwd;
  76
  77   initialize_main (&argc, &argv);
  78   program_name = argv[0];
  79   setlocale (LC_ALL, "");
  80   bindtextdomain (PACKAGE, LOCALEDIR);
  81   textdomain (PACKAGE);
  82
  83   initialize_exit_failure (SETUIDGID_FAILURE);
  84   atexit (close_stdout);
  85
  86   parse_long_options (argc, argv, PROGRAM_NAME, GNU_PACKAGE, VERSION,
  87                       usage, AUTHORS, (char const *) NULL);
  88
  89   /* The above handles --help and --version.
  90      Since there is no other invocation of getopt, handle `--' here.  */
  91   if (argc > 1 && STREQ (argv[1], "--"))
  92     {
  93       --argc;
  94       ++argv;
  95     }
  96
  97   if (argc <= 2)
  98     {
  99       error (0, 0, _("too few arguments"));
 100       usage (SETUIDGID_FAILURE);
 101     }
 102
 103   user_id = argv[1];
 104   pwd = getpwnam (user_id);
 105   if (pwd == NULL)
 106     error (SETUIDGID_FAILURE, errno,
 107            _("unknown user-ID: %s"), quote (user_id));
 108
 109   if (setgroups (1, &pwd->pw_gid))
 110     error (SETUIDGID_FAILURE, errno, _("cannot set supplemental group"));
 111
 112   if (setgid (pwd->pw_gid))
 113     error (SETUIDGID_FAILURE, errno,
 114            _("cannot set group-ID to %ld"), (long int) pwd->pw_gid);
 115
 116   if (setuid (pwd->pw_uid))
 117     error (SETUIDGID_FAILURE, errno,
 118            _("cannot set user-ID to %ld"), (long int) pwd->pw_uid);
 119
 120   {
 121     char **cmd = argv + 2;
 122     int exit_status;
 123     execvp (*cmd, cmd);
 124     exit_status = (errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE);
 125
 126     error (0, errno, _("cannot run command %s"), quote (*cmd));
 127     exit (exit_status);
 128   }
 129 }