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 *
try_dlopen(const char * modfn,int * error)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 *
try_dlopen(const char * modfn)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 *
try_module(const char * modpath)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 *
openpam_dynamic(const char * modname)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