src/setuidgid.c

   1 /* setuidgid - run a command with the UID and GID of a specified user
   2    Copyright (C) 2003-2007 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 3 of the License, or
   7    (at your option) 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, see <http://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Jim Meyering  */
  18
  19 #include <config.h>
  20 #include <getopt.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 "mgetgroups.h"
  31 #include "quote.h"
  32
  33 #define PROGRAM_NAME "setuidgid"
  34
  35 /* I wrote this program from scratch, based on the description of
  36    D.J. Bernstein's program: http://cr.yp.to/daemontools/setuidgid.html.  */
  37 #define AUTHORS "Jim Meyering"
  38
  39 #define SETUIDGID_FAILURE 111
  40
  41 char *program_name;
  42
  43 void
  44 usage (int status)
  45 {
  46   if (status != EXIT_SUCCESS)
  47     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  48              program_name);
  49   else
  50     {
  51       printf (_("\
  52 Usage: %s USERNAME COMMAND [ARGUMENT]...\n\
  53   or:  %s OPTION\n\
  54 "),
  55               program_name, program_name);
  56
  57       fputs (_("\
  58 Drop any supplemental groups, assume the user-ID and group-ID of\n\
  59 the specified USERNAME, and run COMMAND with any specified ARGUMENTs.\n\
  60 Exit with status 111 if unable to assume the required user and group ID.\n\
  61 Otherwise, exit with the exit status of COMMAND.\n\
  62 This program is useful only when run by root (user ID zero).\n\
  63 \n\
  64 "), stdout);
  65       fputs (HELP_OPTION_DESCRIPTION, stdout);
  66       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  67       emit_bug_reporting_address ();
  68     }
  69   exit (status);
  70 }
  71
  72 int
  73 main (int argc, char **argv)
  74 {
  75   char const *user_id;
  76   struct passwd *pwd;
  77
  78   initialize_main (&argc, &argv);
  79   program_name = argv[0];
  80   setlocale (LC_ALL, "");
  81   bindtextdomain (PACKAGE, LOCALEDIR);
  82   textdomain (PACKAGE);
  83
  84   initialize_exit_failure (SETUIDGID_FAILURE);
  85   atexit (close_stdout);
  86
  87   parse_long_options (argc, argv, PROGRAM_NAME, PACKAGE_NAME, VERSION,
  88                       usage, AUTHORS, (char const *) NULL);
  89   if (getopt_long (argc, argv, "+", NULL, NULL) != -1)
  90     usage (SETUIDGID_FAILURE);
  91
  92   if (argc <= optind + 1)
  93     {
  94       if (argc < optind + 1)
  95         error (0, 0, _("missing operand"));
  96       else
  97         error (0, 0, _("missing operand after %s"), quote (argv[optind]));
  98       usage (SETUIDGID_FAILURE);
  99     }
 100
 101   user_id = argv[optind];
 102   pwd = getpwnam (user_id);
 103   if (pwd == NULL)
 104     error (SETUIDGID_FAILURE, errno,
 105            _("unknown user-ID: %s"), quote (user_id));
 106
 107 #if HAVE_SETGROUPS
 108   {
 109     GETGROUPS_T *groups;
 110     int n_groups = mgetgroups (user_id, pwd->pw_gid, &groups);
 111     if (n_groups < 0)
 112       {
 113         n_groups = 1;
 114         groups = xmalloc (sizeof *groups);
 115         *groups = pwd->pw_gid;
 116       }
 117
 118     if (0 < n_groups && setgroups (n_groups, groups))
 119       error (SETUIDGID_FAILURE, errno, _("cannot set supplemental group(s)"));
 120
 121     free (groups);
 122   }
 123 #endif
 124
 125   if (setgid (pwd->pw_gid))
 126     error (SETUIDGID_FAILURE, errno,
 127            _("cannot set group-ID to %lu"), (unsigned long int) pwd->pw_gid);
 128
 129   if (setuid (pwd->pw_uid))
 130     error (SETUIDGID_FAILURE, errno,
 131            _("cannot set user-ID to %lu"), (unsigned long int) pwd->pw_uid);
 132
 133   {
 134     char **cmd = argv + optind + 1;
 135     int exit_status;
 136     execvp (*cmd, cmd);
 137     exit_status = (errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE);
 138
 139     error (0, errno, _("cannot run command %s"), quote (*cmd));
 140     exit (exit_status);
 141   }
 142 }