source: openpam/trunk/lib/openpam_dynamic.c @ 594

Last change on this file since 594 was 594, checked in by Dag-Erling Smørgrav, 9 years ago

Add an experimental mechanism for enabling / disabling optional features.
Use it to control policy and module file checks. The default settings
correspond to the current behavior: disallow path separators in policy
names, but allow them in module names; verify ownership and permissions
for both policy files and modules.

  • Property svn:keywords set to Id
File size: 4.8 KB
Line 
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 * $Id: openpam_dynamic.c 594 2012-04-14 14:18:41Z des $
36 */
37
38#ifdef HAVE_CONFIG_H
39# include "config.h"
40#endif
41
42#include <dlfcn.h>
43#include <fcntl.h>
44#include <errno.h>
45#include <stdio.h>
46#include <stdlib.h>
47#include <string.h>
48#include <unistd.h>
49
50#include <security/pam_appl.h>
51
52#include "openpam_impl.h"
53
54#ifndef RTLD_NOW
55#define RTLD_NOW RTLD_LAZY
56#endif
57
58/*
59 * OpenPAM internal
60 *
61 * Perform sanity checks and attempt to load a module
62 */
63
64#ifdef HAVE_FDLOPEN
65static void *
66try_dlopen(const char *modfn)
67{
68        void *dlh;
69        int fd;
70
71        if ((fd = open(modfn, O_RDONLY)) < 0)
72                return (NULL);
73        if (OPENPAM_FEATURE(VERIFY_MODULE_FILE) &&
74            openpam_check_desc_owner_perms(modfn, fd) != 0) {
75                close(fd);
76                return (NULL);
77        }
78        if ((dlh = fdlopen(fd, RTLD_NOW)) == NULL) {
79                openpam_log(PAM_LOG_ERROR, "%s: %s", modfn, dlerror());
80                close(fd);
81                errno = 0;
82                return (NULL);
83        }
84        close(fd);
85        return (dlh);
86}
87#else
88static void *
89try_dlopen(const char *modfn)
90{
91        int check_module_file;
92        void *dlh;
93
94        openpam_get_feature(OPENPAM_FEATURE_CHECK_MODULE_FILE,
95            &check_module_file);
96        if (check_module_file &&
97            openpam_check_path_owner_perms(modfn) != 0)
98                return (NULL);
99        if ((dlh = dlopen(modfn, RTLD_NOW)) == NULL) {
100                openpam_log(PAM_LOG_ERROR, "%s: %s", modfn, dlerror());
101                errno = 0;
102                return (NULL);
103        }
104        return (dlh);
105}
106#endif
107
108/*
109 * OpenPAM internal
110 *
111 * Locate a dynamically linked module
112 */
113
114pam_module_t *
115openpam_dynamic(const char *path)
116{
117        const pam_module_t *dlmodule;
118        pam_module_t *module;
119        const char *prefix;
120        char *vpath;
121        void *dlh;
122        int i, serrno;
123
124        dlh = NULL;
125
126        /* Prepend the standard prefix if not an absolute pathname. */
127        if (path[0] != '/')
128                prefix = OPENPAM_MODULES_DIR;
129        else
130                prefix = "";
131
132        /* try versioned module first, then unversioned module */
133        if (asprintf(&vpath, "%s%s.%d", prefix, path, LIB_MAJ) < 0)
134                goto err;
135        if ((dlh = try_dlopen(vpath)) == NULL && errno == ENOENT) {
136                *strrchr(vpath, '.') = '\0';
137                dlh = try_dlopen(vpath);
138        }
139        if (dlh == NULL)
140                goto err;
141        if ((module = calloc(1, sizeof *module)) == NULL)
142                goto buf_err;
143        if ((module->path = strdup(path)) == NULL)
144                goto buf_err;
145        module->dlh = dlh;
146        dlmodule = dlsym(dlh, "_pam_module");
147        for (i = 0; i < PAM_NUM_PRIMITIVES; ++i) {
148                if (dlmodule) {
149                        module->func[i] = dlmodule->func[i];
150                } else {
151                        module->func[i] =
152                            (pam_func_t)dlsym(dlh, pam_sm_func_name[i]);
153                        /*
154                         * This openpam_log() call is a major source of
155                         * log spam, and the cases that matter are caught
156                         * and logged in openpam_dispatch().  This would
157                         * be less problematic if dlerror() returned an
158                         * error code so we could log an error only when
159                         * dlsym() failed for a reason other than "no such
160                         * symbol".
161                         */
162#if 0
163                        if (module->func[i] == NULL)
164                                openpam_log(PAM_LOG_DEBUG, "%s: %s(): %s",
165                                    path, pam_sm_func_name[i], dlerror());
166#endif
167                }
168        }
169        FREE(vpath);
170        return (module);
171buf_err:
172        serrno = errno;
173        if (dlh != NULL)
174                dlclose(dlh);
175        FREE(module);
176        errno = serrno;
177err:
178        serrno = errno;
179        if (errno != 0)
180                openpam_log(PAM_LOG_ERROR, "%s: %m", vpath);
181        FREE(vpath);
182        errno = serrno;
183        return (NULL);
184}
185
186/*
187 * NOPARSE
188 */
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