1 /* $NetBSD: openpam_dynamic.c,v 1.3 2017/05/06 19:50:09 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2002-2003 Networks Associates Technology, Inc. 5 * Copyright (c) 2004-2011 Dag-Erling Smørgrav 6 * All rights reserved. 7 * 8 * This software was developed for the FreeBSD Project by ThinkSec AS and 9 * Network Associates Laboratories, the Security Research Division of 10 * Network Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 11 * ("CBOSS"), as part of the DARPA CHATS research program. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. The name of the author may not be used to endorse or promote 22 * products derived from this software without specific prior written 23 * permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * $OpenPAM: openpam_dynamic.c 938 2017-04-30 21:34:42Z des $ 38 */ 39 40 #ifdef HAVE_CONFIG_H 41 # include "config.h" 42 #endif 43 44 #include <sys/cdefs.h> 45 __RCSID("$NetBSD: openpam_dynamic.c,v 1.3 2017/05/06 19:50:09 christos Exp $"); 46 47 #include <sys/param.h> 48 49 #include <dlfcn.h> 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <stdio.h> 53 #include <stdlib.h> 54 #include <string.h> 55 #include <unistd.h> 56 57 #include <security/pam_appl.h> 58 59 #include "openpam_impl.h" 60 #include "openpam_asprintf.h" 61 #include "openpam_ctype.h" 62 #include "openpam_dlfunc.h" 63 64 #ifndef RTLD_NOW 65 #define RTLD_NOW RTLD_LAZY 66 #endif 67 68 /* 69 * OpenPAM internal 70 * 71 * Perform sanity checks and attempt to load a module 72 */ 73 74 #ifdef HAVE_FDLOPEN 75 static void * 76 try_dlopen(const char *modfn, int *error) 77 { 78 void *dlh; 79 int fd; 80 81 openpam_log(PAM_LOG_LIBDEBUG, "dlopen(%s)", modfn); 82 if ((fd = open(modfn, O_RDONLY)) < 0) { 83 if (errno != ENOENT) 84 openpam_log(PAM_LOG_ERROR, "%s: %m", modfn); 85 return (NULL); 86 } 87 if (OPENPAM_FEATURE(VERIFY_MODULE_FILE) && 88 openpam_check_desc_owner_perms(modfn, fd) != 0) { 89 close(fd); 90 return (NULL); 91 } 92 if ((dlh = fdlopen(fd, RTLD_NOW)) == NULL) { 93 openpam_log(PAM_LOG_ERROR, "%s: %s", modfn, dlerror()); 94 close(fd); 95 errno = 0; 96 return (NULL); 97 } 98 close(fd); 99 return (dlh); 100 } 101 #else 102 static void * 103 try_dlopen(const char *modfn) 104 { 105 int check_module_file; 106 void *dlh; 107 108 openpam_log(PAM_LOG_LIBDEBUG, "dlopen(%s)", modfn); 109 openpam_get_feature(OPENPAM_VERIFY_MODULE_FILE, 110 &check_module_file); 111 if (check_module_file && 112 openpam_check_path_owner_perms(modfn) != 0) 113 return (NULL); 114 if ((dlh = dlopen(modfn, RTLD_NOW)) == NULL) { 115 openpam_log(PAM_LOG_ERROR, "%s: %s", modfn, dlerror()); 116 errno = 0; 117 return (NULL); 118 } 119 return (dlh); 120 } 121 #endif 122 123 /* 124 * Try to load a module from the suggested location. 125 */ 126 static pam_module_t * 127 try_module(const char *modpath) 128 { 129 const pam_module_t *dlmodule; 130 pam_module_t *module; 131 int i, serrno; 132 133 if ((module = calloc(1, sizeof *module)) == NULL || 134 (module->path = strdup(modpath)) == NULL || 135 (module->dlh = try_dlopen(modpath)) == NULL) 136 goto err; 137 dlmodule = dlsym(module->dlh, "_pam_module"); 138 for (i = 0; i < PAM_NUM_PRIMITIVES; ++i) { 139 if (dlmodule) { 140 module->func[i] = dlmodule->func[i]; 141 } else { 142 module->func[i] = (pam_func_t)dlfunc(module->dlh, 143 pam_sm_func_name[i]); 144 /* 145 * This openpam_log() call is a major source of 146 * log spam, and the cases that matter are caught 147 * and logged in openpam_dispatch(). This would 148 * be less problematic if dlerror() returned an 149 * error code so we could log an error only when 150 * dlfunc() failed for a reason other than "no 151 * such symbol". 152 */ 153 #if 0 154 if (module->func[i] == NULL) 155 openpam_log(PAM_LOG_LIBDEBUG, "%s: %s(): %s", 156 modpath, pam_sm_func_name[i], dlerror()); 157 #endif 158 } 159 } 160 return (module); 161 err: 162 serrno = errno; 163 if (module != NULL) { 164 if (module->dlh != NULL) 165 dlclose(module->dlh); 166 if (module->path != NULL) 167 FREE(module->path); 168 FREE(module); 169 } 170 errno = serrno; 171 if (serrno != 0 && serrno != ENOENT) 172 openpam_log(PAM_LOG_ERROR, "%s: %m", modpath); 173 errno = serrno; 174 return (NULL); 175 } 176 177 /* 178 * OpenPAM internal 179 * 180 * Locate a dynamically linked module 181 */ 182 183 pam_module_t * 184 openpam_dynamic(const char *modname) 185 { 186 pam_module_t *module; 187 char modpath[PATH_MAX]; 188 const char **path, *p; 189 int has_so, has_ver; 190 int dot, len; 191 192 /* 193 * Simple case: module name contains path separator(s) 194 */ 195 if (strchr(modname, '/') != NULL) { 196 /* 197 * Absolute paths are not allowed if RESTRICT_MODULE_NAME 198 * is in effect (default off). Relative paths are never 199 * allowed. 200 */ 201 if (OPENPAM_FEATURE(RESTRICT_MODULE_NAME) || 202 modname[0] != '/') { 203 openpam_log(PAM_LOG_ERROR, 204 "invalid module name: %s", modname); 205 return (NULL); 206 } 207 return (try_module(modname)); 208 } 209 210 /* 211 * Check for .so and version sufixes 212 */ 213 p = strchr(modname, '\0'); 214 has_ver = has_so = 0; 215 while (is_digit(*p)) 216 --p; 217 if (*p == '.' && *++p != '\0') { 218 /* found a numeric suffix */ 219 has_ver = 1; 220 /* assume that .so is either present or unneeded */ 221 has_so = 1; 222 } else if (*p == '\0' && p >= modname + sizeof PAM_SOEXT && 223 strcmp(p - sizeof PAM_SOEXT + 1, PAM_SOEXT) == 0) { 224 /* found .so suffix */ 225 has_so = 1; 226 } 227 228 /* 229 * Complicated case: search for the module in the usual places. 230 */ 231 for (path = openpam_module_path; *path != NULL; ++path) { 232 /* 233 * Assemble the full path, including the version suffix. Take 234 * note of where the suffix begins so we can cut it off later. 235 */ 236 if (has_ver) 237 len = snprintf(modpath, sizeof modpath, "%s/%s%n", 238 *path, modname, &dot); 239 else if (has_so) 240 len = snprintf(modpath, sizeof modpath, "%s/%s%n.%d", 241 *path, modname, &dot, LIB_MAJ); 242 else 243 len = snprintf(modpath, sizeof modpath, "%s/%s%s%n.%d", 244 *path, modname, PAM_SOEXT, &dot, LIB_MAJ); 245 /* check for overflow */ 246 if (len < 0 || (unsigned int)len >= sizeof modpath) { 247 errno = ENOENT; 248 continue; 249 } 250 /* try the versioned path */ 251 if ((module = try_module(modpath)) != NULL) 252 return (module); 253 if (errno == ENOENT && modpath[dot] != '\0') { 254 /* no luck, try the unversioned path */ 255 modpath[dot] = '\0'; 256 if ((module = try_module(modpath)) != NULL) 257 return (module); 258 } 259 } 260 261 /* :( */ 262 return (NULL); 263 } 264 265 /* 266 * NOPARSE 267 */ 268