tools/wrapper.c

   1 /*
   2 ** Copyright (C) 2000 by Kevin L. Mitchell <klmitch@mit.edu>
   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 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, write to the Free Software
  16 ** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  17 **
  18 ** @(#)$Id: wrapper.c,v 1.3 2004/05/15 14:50:09 entrope Exp $
  19 */
  20 #include <string.h>
  21 #include <stdlib.h>
  22 #include <stdio.h>
  23 #include <pwd.h>
  24 #include <grp.h>
  25 #include <sys/time.h>
  26 #include <sys/types.h>
  27 #include <sys/resource.h>
  28 #include <unistd.h>
  29
  30 /*
  31  * Try and find the correct name to use with getrlimit() for setting the max.
  32  * number of files allowed to be open by this process.
  33  *
  34  * Shamelessly stolen from ircu...
  35  */
  36 #ifdef RLIMIT_FDMAX
  37 #define RLIMIT_FD_MAX RLIMIT_FDMAX
  38 #else
  39 #ifdef RLIMIT_NOFILE
  40 #define RLIMIT_FD_MAX RLIMIT_NOFILE
  41 #else
  42 #ifdef RLIMIT_OPEN_MAX
  43 #define RLIMIT_FD_MAX RLIMIT_OPEN_MAX
  44 #else
  45 #error Unable to find a valid RLIMIT_FD_MAX
  46 #endif
  47 #endif
  48 #endif
  49
  50 /*fix for change uid/gid with chroot #ubra 08/02/03*/
  51 int uid, gid;
  52
  53 /*
  54  * Set the hard and soft limits for maximum file descriptors.
  55  */
  56 int
  57 set_fdlimit(unsigned int max_descriptors)
  58 {
  59   struct rlimit limit;
  60
  61   limit.rlim_max = limit.rlim_cur = max_descriptors;
  62
  63   return setrlimit(RLIMIT_FD_MAX, &limit);
  64 }
  65
  66 /*
  67  * Change directories to the indicated root directory, then make it the
  68  * root directory.
  69  */
  70 int
  71 change_root(char *root)
  72 {
  73   if (chdir(root))
  74     return -1;
  75   if (chroot(root))
  76     return -1;
  77
  78   return 0;
  79 }
  80
  81 /*
  82  * Change the user and group ids--including supplementary groups!--as
  83  * appropriate.
  84  *
  85  * fix for change uid/gid with chroot #ubra 08/02/03
  86  * old change_user() got splited into get_user() and set_user()
  87  */
  88 int
  89 get_user(char *user, char *group)
  90 {
  91   struct passwd *pwd;
  92   struct group *grp;
  93   char *tmp;
  94
  95   /* Track down a struct passwd describing the desired user */
  96   uid = strtol(user, &tmp, 10); /* was the user given as a number? */
  97   if (*tmp) { /* strtol() failed to parse; look up as a user name */
  98     if (!(pwd = getpwnam(user)))
  99       return -1;
 100   } else if (!(pwd = getpwuid(uid))) /* look up uid */
 101       return -1;
 102
 103   uid = pwd->pw_uid; /* uid to change to */
 104   gid = pwd->pw_gid; /* default gid for user */
 105
 106   if (group) { /* a group was specified; track down struct group */
 107     gid = strtol(group, &tmp, 10); /* was the group given as a number? */
 108     if (*tmp) { /* strtol() failed to parse; look up as a group name */
 109       if (!(grp = getgrnam(group)))
 110         return -1;
 111     } else if (!(grp = getgrgid(gid))) /* look up gid */
 112       return -1;
 113
 114     gid = grp->gr_gid; /* set the gid */
 115   }
 116
 117   if (initgroups(pwd->pw_name, gid)) /* initialize supplementary groups */
 118     return -1;
 119   return 0; /* success! */
 120 }
 121
 122 int
 123 set_user(void) {
 124   if (setgid(gid)) /* change our current group */
 125     return -1;
 126   if (setuid(uid)) /* change our current user */
 127     return -1;
 128
 129   return 0; /* success! */
 130 }
 131
 132 /*
 133  * Explain how to use this program.
 134  */
 135 void
 136 usage(char *prog, int retval)
 137 {
 138   fprintf(stderr, "Usage: %s [-u <user>] [-g <group>] [-l <limit>] [-c <root>]"
 139           " -- \\\n\t\t<cmd> [<cmdargs>]\n", prog);
 140   fprintf(stderr, "       %s -h\n", prog);
 141
 142   exit(retval);
 143 }
 144
 145 int
 146 main(int argc, char **argv)
 147 {
 148   int c, limit = -1;
 149   char *prog, *user = 0, *group = 0, *root = 0;
 150
 151   /* determine program name for error reporting */
 152   if ((prog = strrchr(argv[0], '/')))
 153     prog++;
 154   else
 155     prog = argv[0];
 156
 157   /* process command line arguments */
 158   while ((c = getopt(argc, argv, "hu:g:l:c:")) > 0)
 159     switch (c) {
 160     case 'h': /* requested help */
 161       usage(prog, 0);
 162       break;
 163
 164     case 'u': /* suggested a user */
 165       user = optarg;
 166       break;
 167
 168     case 'g': /* suggested a group */
 169       group = optarg;
 170       break;
 171
 172     case 'l': /* file descriptor limit */
 173       limit = strtol(optarg, 0, 10);
 174       break;
 175
 176     case 'c': /* select a root directory */
 177       root = optarg;
 178       break;
 179
 180     default: /* unknown command line argument */
 181       usage(prog, 1);
 182       break;
 183     }
 184
 185   /* Not enough arguments; we must have a command to execute! */
 186   if (optind >= argc)
 187     usage(prog, 1);
 188
 189   if (limit > 0) /* set the requested fd limit */
 190     if (set_fdlimit(limit) < 0) {
 191       perror(prog);
 192       return 1;
 193     }
 194
 195   if(user) /* get the selected user account uid/gid*/
 196    if (get_user(user, group)) {
 197      perror(prog);
 198      return 1;
 199    }
 200
 201
 202   if (root) /* change root directories */
 203     if (change_root(root)) {
 204       perror(prog);
 205       return 1;
 206     }
 207
 208   if (user) /* change to selected user account */
 209     if (set_user()) {
 210       perror(prog);
 211       return 1;
 212     }
 213
 214   /* execute the requested command */
 215   execvp(argv[optind], argv + optind);
 216
 217   /* If we got here, execvp() failed; report the error */
 218   perror(prog);
 219   return 1;
 220 }