src/runas.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2000-2001 Silicon Graphics, Inc.
   4  * All Rights Reserved.
   5  */
   6
   7 /*
   8  * Run a command with a particular
   9  *    - effective user id
  10  *    - effective group id
  11  *    - supplementary group list
  12  */
  13
  14 #include "global.h"
  15 #include <grp.h>
  16
  17
  18
  19 char *prog;
  20
  21 void usage(void)
  22 {
  23     fprintf(stderr, "usage: %s [-u uid] [-g gid] [-s gid] cmd\n"
  24            "flags:\n"
  25            "    -u - effective user-id\n"
  26            "    -g - effective group-id\n"
  27            "    -s - supplementary group-id\n", prog);
  28
  29 }
  30
  31 #define SUP_MAX 20
  32
  33 int
  34 main(int argc, char **argv)
  35 {
  36         int c;
  37         uid_t uid = -1;
  38         gid_t gid = -1;
  39         char **cmd;
  40         gid_t sgids[SUP_MAX];
  41         int sup_cnt = 0;
  42         char *p;
  43
  44         prog = basename(argv[0]);
  45         for (p = prog; *p; p++) {
  46                 if (*p == '/') {
  47                         prog = p + 1;
  48                 }
  49         }
  50
  51
  52         while ((c = getopt(argc, argv, "u:g:s:")) != -1) {
  53                 switch (c) {
  54                 case 'u':
  55                         uid = atoi(optarg);
  56                         break;
  57                 case 'g':
  58                         gid = atoi(optarg);
  59                         break;
  60                 case 's':
  61                         if (sup_cnt+1 > SUP_MAX) {
  62                             fprintf(stderr, "%s: too many sup groups\n", prog);
  63                             exit(1);
  64                         }
  65                         sgids[sup_cnt++] = atoi(optarg);
  66                         break;
  67                 case '?':
  68                         usage();
  69                         exit(1);
  70                 }
  71         }
  72
  73         /* build up the cmd */
  74         if (optind == argc) {
  75             usage();
  76             exit(1);
  77         }
  78         else {
  79             char **p;
  80             p = cmd = (char **)malloc(sizeof(char *) * (argc - optind + 1));
  81             for ( ; optind < argc; optind++, p++) {
  82                 *p = strdup(argv[optind]);
  83             }
  84             *p = NULL;
  85         }
  86
  87         if (gid != -1) {
  88             if (setgid(gid) == -1) {
  89                 fprintf(stderr, "%s: setgid(%d) failed: %s\n",
  90                         prog, (int)gid, strerror(errno));
  91                 exit(1);
  92             }
  93         }
  94
  95         if (gid != -1 || sup_cnt != 0) {
  96             if (setgroups(sup_cnt, sgids) == -1) {
  97                 fprintf(stderr, "%s: setgroups() failed: %s\n",
  98                         prog, strerror(errno));
  99                 exit(1);
 100             }
 101         }
 102
 103         if (uid != -1) {
 104             if (setuid(uid) == -1) {
 105                 fprintf(stderr, "%s: setuid(%d) failed: %s\n",
 106                         prog, (int)uid, strerror(errno));
 107                 exit(1);
 108             }
 109         }
 110
 111         execvp(cmd[0], cmd);
 112         fprintf(stderr, "%s: %s\n", cmd[0], strerror(errno));
 113         exit(1);
 114 }