1 /* $NetBSD: pam_exec.c,v 1.7 2013/12/29 22:54:58 christos 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 1.7 2013/12/29 22:54:58 christos 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 size_t envlen, i, nitems; 74 int pam_err, status; 75 char **envlist, **tmp; 76 volatile int childerr; 77 pid_t pid; 78 79 if (argc < 1) 80 return (PAM_SERVICE_ERR); 81 82 /* 83 * XXX For additional credit, divert child's stdin/stdout/stderr 84 * to the conversation function. 85 */ 86 87 /* 88 * Set up the child's environment list. It consists of the PAM 89 * environment, plus a few hand-picked PAM items. 90 */ 91 envlist = pam_getenvlist(pamh); 92 for (envlen = 0; envlist[envlen] != NULL; ++envlen) 93 /* nothing */ ; 94 nitems = sizeof(env_items) / sizeof(*env_items); 95 tmp = realloc(envlist, (envlen + nitems + 1) * sizeof(*envlist)); 96 if (tmp == NULL) { 97 openpam_free_envlist(envlist); 98 return (PAM_BUF_ERR); 99 } 100 envlist = tmp; 101 for (i = 0; i < nitems; ++i) { 102 const void *item; 103 char *envstr; 104 105 pam_err = pam_get_item(pamh, env_items[i].item, &item); 106 if (pam_err != PAM_SUCCESS || item == NULL) 107 continue; 108 asprintf(&envstr, "%s=%s", env_items[i].name, 109 (const char *)item); 110 if (envstr == NULL) { 111 openpam_free_envlist(envlist); 112 return (PAM_BUF_ERR); 113 } 114 envlist[envlen++] = envstr; 115 envlist[envlen] = NULL; 116 } 117 118 /* 119 * Fork and run the command. By using vfork() instead of fork(), 120 * we can distinguish between an execve() failure and a non-zero 121 * exit code from the command. 122 */ 123 childerr = 0; 124 if ((pid = vfork()) == 0) { 125 /*LINTED const cast*/ 126 execve(argv[0], (char **)__UNCONST(argv), envlist); 127 childerr = errno; 128 _exit(1); 129 } 130 openpam_free_envlist(envlist); 131 if (pid == -1) { 132 openpam_log(PAM_LOG_ERROR, "vfork(): %s", strerror(errno)); 133 return (PAM_SYSTEM_ERR); 134 } 135 if (waitpid(pid, &status, 0) == -1) { 136 openpam_log(PAM_LOG_ERROR, "waitpid(): %s", strerror(errno)); 137 return (PAM_SYSTEM_ERR); 138 } 139 if (childerr != 0) { 140 openpam_log(PAM_LOG_ERROR, "execve(): %s", strerror(errno)); 141 return (PAM_SYSTEM_ERR); 142 } 143 if (WIFSIGNALED(status)) { 144 openpam_log(PAM_LOG_ERROR, "%s caught signal %d%s", 145 argv[0], WTERMSIG(status), 146 WCOREDUMP(status) ? " (core dumped)" : ""); 147 return (PAM_SYSTEM_ERR); 148 } 149 if (!WIFEXITED(status)) { 150 openpam_log(PAM_LOG_ERROR, "unknown status 0x%x", status); 151 return (PAM_SYSTEM_ERR); 152 } 153 if (WEXITSTATUS(status) != 0) { 154 openpam_log(PAM_LOG_ERROR, "%s returned code %d", 155 argv[0], WEXITSTATUS(status)); 156 return (PAM_SYSTEM_ERR); 157 } 158 return (PAM_SUCCESS); 159 } 160 161 PAM_EXTERN int 162 pam_sm_authenticate(pam_handle_t *pamh, int flags, 163 int argc, const char *argv[]) 164 { 165 166 return (_pam_exec(pamh, flags, argc, argv)); 167 } 168 169 PAM_EXTERN int 170 pam_sm_setcred(pam_handle_t *pamh, int flags, 171 int argc, const char *argv[]) 172 { 173 174 return (_pam_exec(pamh, flags, argc, argv)); 175 } 176 177 PAM_EXTERN int 178 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags, 179 int argc, const char *argv[]) 180 { 181 182 return (_pam_exec(pamh, flags, argc, argv)); 183 } 184 185 PAM_EXTERN int 186 pam_sm_open_session(pam_handle_t *pamh, int flags, 187 int argc, const char *argv[]) 188 { 189 190 return (_pam_exec(pamh, flags, argc, argv)); 191 } 192 193 PAM_EXTERN int 194 pam_sm_close_session(pam_handle_t *pamh, int flags, 195 int argc, const char *argv[]) 196 { 197 198 return (_pam_exec(pamh, flags, argc, argv)); 199 } 200 201 PAM_EXTERN int 202 pam_sm_chauthtok(pam_handle_t *pamh, int flags, 203 int argc, const char *argv[]) 204 { 205 206 return (_pam_exec(pamh, flags, argc, argv)); 207 } 208 209 PAM_MODULE_ENTRY("pam_exec"); 210