support/checkgid.c

   1 /* Licensed to the Apache Software Foundation (ASF) under one or more
   2  * contributor license agreements.  See the NOTICE file distributed with
   3  * this work for additional information regarding copyright ownership.
   4  * The ASF licenses this file to You under the Apache License, Version 2.0
   5  * (the "License"); you may not use this file except in compliance with
   6  * the License.  You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 /*
  18  * Given one or more group identifers on the command line (e.g.,
  19  * "httpd" or "#-1"), figure out whether they'll be valid for
  20  * the server to use at run-time.
  21  *
  22  * If a groupname isn't found, or we can't setgid() to it, return
  23  * -1.  If all groups are valid, return 0.
  24  *
  25  * This may need to be run as the superuser for the setgid() to
  26  * succeed; running it as any other user may result in a false
  27  * negative.
  28  */
  29
  30 #include "ap_config.h"
  31 #if APR_HAVE_STDIO_H
  32 #include <stdio.h>
  33 #endif
  34 #if APR_HAVE_STDLIB_H
  35 #include <stdlib.h>
  36 #endif
  37 #if APR_HAVE_SYS_TYPES_H
  38 #include <sys/types.h>
  39 #endif
  40 #if HAVE_GRP_H
  41 #include <grp.h>
  42 #endif
  43 #if APR_HAVE_UNISTD_H
  44 #include <unistd.h>
  45 #endif
  46
  47 int main(int argc, char *argv[])
  48 {
  49     int i;
  50     int result;
  51     gid_t gid;
  52     struct group *grent;
  53     struct group fake_grent;
  54
  55     /*
  56      * Assume success. :-)
  57      */
  58     result = 0;
  59     for (i = 1; i < argc; ++i) {
  60         char *arg;
  61         arg = argv[i];
  62
  63         /*
  64          * If it's from a 'Group #-1' statement, get the numeric value
  65          * and skip the group lookup stuff.
  66          */
  67         if (*arg == '#') {
  68             gid = atoi(&arg[1]);
  69             fake_grent.gr_gid = gid;
  70             grent = &fake_grent;
  71         }
  72         else {
  73             grent = getgrnam(arg);
  74         }
  75
  76         /*
  77          * A NULL return means no such group was found, so we're done
  78          * with this one.
  79          */
  80         if (grent == NULL) {
  81             fprintf(stderr, "%s: group '%s' not found\n", argv[0], arg);
  82             result = -1;
  83         }
  84         else {
  85             int check;
  86
  87             /*
  88              * See if we can switch to the numeric GID we have. If so,
  89              * all well and good; if not, well..
  90              */
  91             gid = grent->gr_gid;
  92             check = setgid(gid);
  93             if (check != 0) {
  94                 fprintf(stderr, "%s: invalid group '%s'\n", argv[0], arg);
  95                 perror(argv[0]);
  96                 result = -1;
  97             }
  98         }
  99     }
 100     /*
 101      * Worst-case return value.
 102      */
 103     return result;
 104 }
 105 /*
 106  * Local Variables:
 107  * mode: C
 108  * c-file-style: "bsd"
 109  * End:
 110  */