lib/pam_module/pam_exec/pam_exec.c

   1 /*-
   2  * Copyright (c) 2001,2003 Networks Associates Technology, Inc.
   3  * All rights reserved.
   4  *
   5  * This software was developed for the FreeBSD Project by ThinkSec AS and
   6  * NAI Labs, the Security Research Division of Network Associates, Inc.
   7  * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
   8  * DARPA CHATS research program.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. The name of the author may not be used to endorse or promote
  19  *    products derived from this software without specific prior written
  20  *    permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $FreeBSD: src/lib/libpam/modules/pam_exec/pam_exec.c,v 1.6 2006/11/10 23:33:25 des Exp $
  35  */
  36
  37 #include <sys/types.h>
  38 #include <sys/wait.h>
  39
  40 #include <errno.h>
  41 #include <stdlib.h>
  42 #include <stdio.h>
  43 #include <string.h>
  44 #include <unistd.h>
  45
  46 #include <security/pam_appl.h>
  47 #include <security/pam_modules.h>
  48 #include <security/openpam.h>
  49
  50 #define ENV_ITEM(n) { (n), #n }
  51 static struct {
  52         int item;
  53         const char *name;
  54 } env_items[] = {
  55         ENV_ITEM(PAM_SERVICE),
  56         ENV_ITEM(PAM_USER),
  57         ENV_ITEM(PAM_TTY),
  58         ENV_ITEM(PAM_RHOST),
  59         ENV_ITEM(PAM_RUSER),
  60 };
  61
  62 static int
  63 _pam_exec(pam_handle_t *pamh __unused, int flags __unused,
  64           int argc, const char *argv[])
  65 {
  66         int envlen, i, nitems, pam_err, status;
  67         char **envlist, **tmp;
  68         volatile int childerr;
  69         pid_t pid;
  70
  71         if (argc < 1)
  72                 return (PAM_SERVICE_ERR);
  73
  74         /*
  75          * XXX For additional credit, divert child's stdin/stdout/stderr
  76          * to the conversation function.
  77          */
  78
  79         /*
  80          * Set up the child's environment list.  It consists of the PAM
  81          * environment, plus a few hand-picked PAM items.
  82          */
  83         envlist = pam_getenvlist(pamh);
  84         for (envlen = 0; envlist[envlen] != NULL; ++envlen)
  85                 /* nothing */ ;
  86         nitems = sizeof(env_items) / sizeof(*env_items);
  87         tmp = realloc(envlist, (envlen + nitems + 1) * sizeof(*envlist));
  88         if (tmp == NULL) {
  89                 openpam_free_envlist(envlist);
  90                 return (PAM_BUF_ERR);
  91         }
  92         envlist = tmp;
  93         for (i = 0; i < nitems; ++i) {
  94                 const void *item;
  95                 char *envstr;
  96
  97                 pam_err = pam_get_item(pamh, env_items[i].item, &item);
  98                 if (pam_err != PAM_SUCCESS || item == NULL)
  99                         continue;
 100                 asprintf(&envstr, "%s=%s", env_items[i].name, item);
 101                 if (envstr == NULL) {
 102                         openpam_free_envlist(envlist);
 103                         return (PAM_BUF_ERR);
 104                 }
 105                 envlist[envlen++] = envstr;
 106                 envlist[envlen] = NULL;
 107         }
 108
 109         /*
 110          * Fork and run the command.  By using vfork() instead of fork(),
 111          * we can distinguish between an execve() failure and a non-zero
 112          * exit code from the command.
 113          */
 114         childerr = 0;
 115         if ((pid = vfork()) == 0) {
 116                 execve(argv[0], (char * const *)argv, (char * const *)envlist);
 117                 childerr = errno;
 118                 _exit(1);
 119         }
 120         openpam_free_envlist(envlist);
 121         if (pid == -1) {
 122                 openpam_log(PAM_LOG_ERROR, "vfork(): %m");
 123                 return (PAM_SYSTEM_ERR);
 124         }
 125         if (waitpid(pid, &status, 0) == -1) {
 126                 openpam_log(PAM_LOG_ERROR, "waitpid(): %m");
 127                 return (PAM_SYSTEM_ERR);
 128         }
 129         if (childerr != 0) {
 130                 openpam_log(PAM_LOG_ERROR, "execve(): %m");
 131                 return (PAM_SYSTEM_ERR);
 132         }
 133         if (WIFSIGNALED(status)) {
 134                 openpam_log(PAM_LOG_ERROR, "%s caught signal %d%s",
 135                     argv[0], WTERMSIG(status),
 136                     WCOREDUMP(status) ? " (core dumped)" : "");
 137                 return (PAM_SYSTEM_ERR);
 138         }
 139         if (!WIFEXITED(status)) {
 140                 openpam_log(PAM_LOG_ERROR, "unknown status 0x%x", status);
 141                 return (PAM_SYSTEM_ERR);
 142         }
 143         if (WEXITSTATUS(status) != 0) {
 144                 openpam_log(PAM_LOG_ERROR, "%s returned code %d",
 145                     argv[0], WEXITSTATUS(status));
 146                 return (PAM_SYSTEM_ERR);
 147         }
 148         return (PAM_SUCCESS);
 149 }
 150
 151 PAM_EXTERN int
 152 pam_sm_authenticate(pam_handle_t *pamh, int flags, int argc, const char *argv[])
 153 {
 154
 155         return (_pam_exec(pamh, flags, argc, argv));
 156 }
 157
 158 PAM_EXTERN int
 159 pam_sm_setcred(pam_handle_t *pamh, int flags, int argc, const char *argv[])
 160 {
 161
 162         return (_pam_exec(pamh, flags, argc, argv));
 163 }
 164
 165 PAM_EXTERN int
 166 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags, int argc, const char *argv[])
 167 {
 168
 169         return (_pam_exec(pamh, flags, argc, argv));
 170 }
 171
 172 PAM_EXTERN int
 173 pam_sm_open_session(pam_handle_t *pamh, int flags, int argc, const char *argv[])
 174 {
 175
 176         return (_pam_exec(pamh, flags, argc, argv));
 177 }
 178
 179 PAM_EXTERN int
 180 pam_sm_close_session(pam_handle_t *pamh, int flags,
 181                      int argc, const char *argv[])
 182 {
 183
 184         return (_pam_exec(pamh, flags, argc, argv));
 185 }
 186
 187 PAM_EXTERN int
 188 pam_sm_chauthtok(pam_handle_t *pamh, int flags, int argc, const char *argv[])
 189 {
 190
 191         return (_pam_exec(pamh, flags, argc, argv));
 192 }
 193
 194 PAM_MODULE_ENTRY("pam_exec");