lib/libpam/modules/pam_exec/pam_exec.c

   1 /*      $NetBSD: pam_exec.c,v 1.3 2005/02/26 16:03:58 thorpej Exp $     */
   2
   3 /*-
   4  * Copyright (c) 2001,2003 Networks Associates Technology, Inc.
   5  * All rights reserved.
   6  *
   7  * This software was developed for the FreeBSD Project by ThinkSec AS and
   8  * NAI Labs, the Security Research Division of Network Associates, Inc.
   9  * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
  10  * DARPA CHATS research program.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. The name of the author may not be used to endorse or promote
  21  *    products derived from this software without specific prior written
  22  *    permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #include <sys/cdefs.h>
  38 #ifdef __FreeBSD__
  39 __FBSDID("$FreeBSD: src/lib/libpam/modules/pam_exec/pam_exec.c,v 1.4 2005/02/01 10:37:07 des Exp $");
  40 #else
  41 __RCSID("$NetBSD: pam_exec.c,v 1.3 2005/02/26 16:03:58 thorpej Exp $");
  42 #endif
  43
  44 #include <sys/types.h>
  45 #include <sys/wait.h>
  46
  47 #include <errno.h>
  48 #include <stdlib.h>
  49 #include <stdio.h>
  50 #include <string.h>
  51 #include <unistd.h>
  52
  53 #include <security/pam_appl.h>
  54 #include <security/pam_modules.h>
  55 #include <security/openpam.h>
  56
  57 #define ENV_ITEM(n) { (n), #n }
  58 static struct {
  59         int item;
  60         const char *name;
  61 } env_items[] = {
  62         ENV_ITEM(PAM_SERVICE),
  63         ENV_ITEM(PAM_USER),
  64         ENV_ITEM(PAM_TTY),
  65         ENV_ITEM(PAM_RHOST),
  66         ENV_ITEM(PAM_RUSER),
  67 };
  68
  69 static int
  70 _pam_exec(pam_handle_t *pamh __unused, int flags __unused,
  71     int argc, const char *argv[])
  72 {
  73         int childerr, envlen, i, nitems, pam_err, status;
  74         char **envlist, **tmp;
  75         pid_t pid;
  76
  77         if (argc < 1)
  78                 return (PAM_SERVICE_ERR);
  79
  80         /*
  81          * XXX For additional credit, divert child's stdin/stdout/stderr
  82          * to the conversation function.
  83          */
  84
  85         /*
  86          * Set up the child's environment list.  It consists of the PAM
  87          * environment, plus a few hand-picked PAM items.
  88          */
  89         envlist = pam_getenvlist(pamh);
  90         for (envlen = 0; envlist[envlen] != NULL; ++envlen)
  91                 /* nothing */ ;
  92         nitems = sizeof(env_items) / sizeof(*env_items);
  93         tmp = realloc(envlist, (envlen + nitems + 1) * sizeof **envlist);
  94         if (tmp == NULL) {
  95                 openpam_free_envlist(envlist);
  96                 return (PAM_BUF_ERR);
  97         }
  98         envlist = tmp;
  99         for (i = 0; i < nitems; ++i) {
 100                 const void *item;
 101                 char *envstr;
 102
 103                 pam_err = pam_get_item(pamh, env_items[i].item, &item);
 104                 if (pam_err != PAM_SUCCESS || item == NULL)
 105                         continue;
 106                 asprintf(&envstr, "%s=%s", env_items[i].name,
 107                     (const char *)item);
 108                 if (envstr == NULL) {
 109                         openpam_free_envlist(envlist);
 110                         return (PAM_BUF_ERR);
 111                 }
 112                 envlist[envlen++] = envstr;
 113                 envlist[envlen] = NULL;
 114         }
 115
 116         /*
 117          * Fork and run the command.  By using vfork() instead of fork(),
 118          * we can distinguish between an execve() failure and a non-zero
 119          * exit code from the command.
 120          */
 121         childerr = 0;
 122         if ((pid = vfork()) == 0) {
 123                 /*LINTED const cast*/
 124                 execve(argv[0], (char **)__UNCONST(argv), envlist);
 125                 childerr = errno;
 126                 _exit(1);
 127         }
 128         openpam_free_envlist(envlist);
 129         if (pid == -1) {
 130                 openpam_log(PAM_LOG_ERROR, "vfork(): %m");
 131                 return (PAM_SYSTEM_ERR);
 132         }
 133         if (waitpid(pid, &status, 0) == -1) {
 134                 openpam_log(PAM_LOG_ERROR, "waitpid(): %m");
 135                 return (PAM_SYSTEM_ERR);
 136         }
 137         if (childerr != 0) {
 138                 openpam_log(PAM_LOG_ERROR, "execve(): %m");
 139                 return (PAM_SYSTEM_ERR);
 140         }
 141         if (WIFSIGNALED(status)) {
 142                 openpam_log(PAM_LOG_ERROR, "%s caught signal %d%s",
 143                     argv[0], WTERMSIG(status),
 144                     WCOREDUMP(status) ? " (core dumped)" : "");
 145                 return (PAM_SYSTEM_ERR);
 146         }
 147         if (!WIFEXITED(status)) {
 148                 openpam_log(PAM_LOG_ERROR, "unknown status 0x%x", status);
 149                 return (PAM_SYSTEM_ERR);
 150         }
 151         if (WEXITSTATUS(status) != 0) {
 152                 openpam_log(PAM_LOG_ERROR, "%s returned code %d",
 153                     argv[0], WEXITSTATUS(status));
 154                 return (PAM_SYSTEM_ERR);
 155         }
 156         return (PAM_SUCCESS);
 157 }
 158
 159 PAM_EXTERN int
 160 pam_sm_authenticate(pam_handle_t *pamh, int flags,
 161     int argc, const char *argv[])
 162 {
 163
 164         return (_pam_exec(pamh, flags, argc, argv));
 165 }
 166
 167 PAM_EXTERN int
 168 pam_sm_setcred(pam_handle_t *pamh, int flags,
 169     int argc, const char *argv[])
 170 {
 171
 172         return (_pam_exec(pamh, flags, argc, argv));
 173 }
 174
 175 PAM_EXTERN int
 176 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags,
 177     int argc, const char *argv[])
 178 {
 179
 180         return (_pam_exec(pamh, flags, argc, argv));
 181 }
 182
 183 PAM_EXTERN int
 184 pam_sm_open_session(pam_handle_t *pamh, int flags,
 185     int argc, const char *argv[])
 186 {
 187
 188         return (_pam_exec(pamh, flags, argc, argv));
 189 }
 190
 191 PAM_EXTERN int
 192 pam_sm_close_session(pam_handle_t *pamh, int flags,
 193     int argc, const char *argv[])
 194 {
 195
 196         return (_pam_exec(pamh, flags, argc, argv));
 197 }
 198
 199 PAM_EXTERN int
 200 pam_sm_chauthtok(pam_handle_t *pamh, int flags,
 201     int argc, const char *argv[])
 202 {
 203
 204         return (_pam_exec(pamh, flags, argc, argv));
 205 }
 206
 207 PAM_MODULE_ENTRY("pam_exec");