1 /* $NetBSD: openpam_dynamic.c,v 1.4 2023/06/30 21:46:20 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 38 #ifdef HAVE_CONFIG_H 39 # include "config.h" 40 #endif 41 42 #include <sys/cdefs.h> 43 __RCSID("$NetBSD: openpam_dynamic.c,v 1.4 2023/06/30 21:46:20 christos Exp $"); 44 45 #include <sys/param.h> 46 47 #include <dlfcn.h> 48 #include <errno.h> 49 #include <fcntl.h> 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include <string.h> 53 #include <unistd.h> 54 55 #include <security/pam_appl.h> 56 57 #include "openpam_impl.h" 58 #include "openpam_asprintf.h" 59 #include "openpam_ctype.h" 60 #include "openpam_dlfunc.h" 61 62 #ifndef RTLD_NOW 63 #define RTLD_NOW RTLD_LAZY 64 #endif 65 66 /* 67 * OpenPAM internal 68 * 69 * Perform sanity checks and attempt to load a module 70 */ 71 72 #ifdef HAVE_FDLOPEN 73 static void * 74 try_dlopen(const char *modfn, int *error) 75 { 76 void *dlh; 77 int fd; 78 79 openpam_log(PAM_LOG_LIBDEBUG, "dlopen(%s)", modfn); 80 if ((fd = open(modfn, O_RDONLY)) < 0) { 81 if (errno != ENOENT) 82 openpam_log(PAM_LOG_ERROR, "%s: %m", modfn); 83 return (NULL); 84 } 85 if (OPENPAM_FEATURE(VERIFY_MODULE_FILE) && 86 openpam_check_desc_owner_perms(modfn, fd) != 0) { 87 close(fd); 88 return (NULL); 89 } 90 if ((dlh = fdlopen(fd, RTLD_NOW)) == NULL) { 91 openpam_log(PAM_LOG_ERROR, "%s: %s", modfn, dlerror()); 92 close(fd); 93 errno = 0; 94 return (NULL); 95 } 96 close(fd); 97 return (dlh); 98 } 99 #else 100 static void * 101 try_dlopen(const char *modfn) 102 { 103 int check_module_file; 104 void *dlh; 105 106 openpam_log(PAM_LOG_LIBDEBUG, "dlopen(%s)", modfn); 107 openpam_get_feature(OPENPAM_VERIFY_MODULE_FILE, 108 &check_module_file); 109 if (check_module_file && 110 openpam_check_path_owner_perms(modfn) != 0) 111 return (NULL); 112 if ((dlh = dlopen(modfn, RTLD_NOW)) == NULL) { 113 openpam_log(PAM_LOG_ERROR, "%s: %s", modfn, dlerror()); 114 errno = 0; 115 return (NULL); 116 } 117 return (dlh); 118 } 119 #endif 120 121 /* 122 * Try to load a module from the suggested location. 123 */ 124 static pam_module_t * 125 try_module(const char *modpath) 126 { 127 const pam_module_t *dlmodule; 128 pam_module_t *module; 129 int i, serrno; 130 131 if ((module = calloc(1, sizeof *module)) == NULL || 132 (module->path = strdup(modpath)) == NULL || 133 (module->dlh = try_dlopen(modpath)) == NULL) 134 goto err; 135 dlmodule = dlsym(module->dlh, "_pam_module"); 136 for (i = 0; i < PAM_NUM_PRIMITIVES; ++i) { 137 if (dlmodule) { 138 module->func[i] = dlmodule->func[i]; 139 } else { 140 module->func[i] = (pam_func_t)dlfunc(module->dlh, 141 pam_sm_func_name[i]); 142 /* 143 * This openpam_log() call is a major source of 144 * log spam, and the cases that matter are caught 145 * and logged in openpam_dispatch(). This would 146 * be less problematic if dlerror() returned an 147 * error code so we could log an error only when 148 * dlfunc() failed for a reason other than "no 149 * such symbol". 150 */ 151 #if 0 152 if (module->func[i] == NULL) 153 openpam_log(PAM_LOG_LIBDEBUG, "%s: %s(): %s", 154 modpath, pam_sm_func_name[i], dlerror()); 155 #endif 156 } 157 } 158 return (module); 159 err: 160 serrno = errno; 161 if (module != NULL) { 162 if (module->dlh != NULL) 163 dlclose(module->dlh); 164 if (module->path != NULL) 165 FREE(module->path); 166 FREE(module); 167 } 168 errno = serrno; 169 if (serrno != 0 && serrno != ENOENT) 170 openpam_log(PAM_LOG_ERROR, "%s: %m", modpath); 171 errno = serrno; 172 return (NULL); 173 } 174 175 /* 176 * OpenPAM internal 177 * 178 * Locate a dynamically linked module 179 */ 180 181 pam_module_t * 182 openpam_dynamic(const char *modname) 183 { 184 pam_module_t *module; 185 char modpath[PATH_MAX]; 186 const char **path, *p; 187 int has_so, has_ver; 188 int dot, len; 189 190 /* 191 * Simple case: module name contains path separator(s) 192 */ 193 if (strchr(modname, '/') != NULL) { 194 /* 195 * Absolute paths are not allowed if RESTRICT_MODULE_NAME 196 * is in effect (default off). Relative paths are never 197 * allowed. 198 */ 199 if (OPENPAM_FEATURE(RESTRICT_MODULE_NAME) || 200 modname[0] != '/') { 201 openpam_log(PAM_LOG_ERROR, 202 "invalid module name: %s", modname); 203 return (NULL); 204 } 205 return (try_module(modname)); 206 } 207 208 /* 209 * Check for .so and version sufixes 210 */ 211 p = strchr(modname, '\0'); 212 has_ver = has_so = 0; 213 while (is_digit(*p)) 214 --p; 215 if (*p == '.' && *++p != '\0') { 216 /* found a numeric suffix */ 217 has_ver = 1; 218 /* assume that .so is either present or unneeded */ 219 has_so = 1; 220 } else if (*p == '\0' && p >= modname + sizeof PAM_SOEXT && 221 strcmp(p - sizeof PAM_SOEXT + 1, PAM_SOEXT) == 0) { 222 /* found .so suffix */ 223 has_so = 1; 224 } 225 226 /* 227 * Complicated case: search for the module in the usual places. 228 */ 229 for (path = openpam_module_path; *path != NULL; ++path) { 230 /* 231 * Assemble the full path, including the version suffix. Take 232 * note of where the suffix begins so we can cut it off later. 233 */ 234 if (has_ver) 235 len = snprintf(modpath, sizeof modpath, "%s/%s%n", 236 *path, modname, &dot); 237 else if (has_so) 238 len = snprintf(modpath, sizeof modpath, "%s/%s%n.%d", 239 *path, modname, &dot, LIB_MAJ); 240 else 241 len = snprintf(modpath, sizeof modpath, "%s/%s%s%n.%d", 242 *path, modname, PAM_SOEXT, &dot, LIB_MAJ); 243 /* check for overflow */ 244 if (len < 0 || (unsigned int)len >= sizeof modpath) { 245 errno = ENOENT; 246 continue; 247 } 248 /* try the versioned path */ 249 if ((module = try_module(modpath)) != NULL) 250 return (module); 251 if (errno == ENOENT && modpath[dot] != '\0') { 252 /* no luck, try the unversioned path */ 253 modpath[dot] = '\0'; 254 if ((module = try_module(modpath)) != NULL) 255 return (module); 256 } 257 } 258 259 /* :( */ 260 return (NULL); 261 } 262 263 /* 264 * NOPARSE 265 */ 266