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