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
36 #ifdef HAVE_CONFIG_H
37 # include "config.h"
38 #endif
39
40 #include <sys/param.h>
41
42 #include <grp.h>
43 #include <limits.h>
44 #include <pwd.h>
45 #include <stdlib.h>
46 #include <unistd.h>
47
48 #include <security/pam_appl.h>
49
50 #include "openpam_impl.h"
51 #include "openpam_cred.h"
52
53 /*
54 * OpenPAM extension
55 *
56 * Temporarily borrow user credentials
57 */
58
59 int
openpam_borrow_cred(pam_handle_t * pamh,const struct passwd * pwd)60 openpam_borrow_cred(pam_handle_t *pamh,
61 const struct passwd *pwd)
62 {
63 struct pam_saved_cred *scred;
64 const void *scredp;
65 int r;
66
67 ENTERI(pwd->pw_uid);
68 r = pam_get_data(pamh, PAM_SAVED_CRED, &scredp);
69 if (r == PAM_SUCCESS && scredp != NULL) {
70 openpam_log(PAM_LOG_LIBDEBUG,
71 "already operating under borrowed credentials");
72 RETURNC(PAM_SYSTEM_ERR);
73 }
74 if (geteuid() != 0 && geteuid() != pwd->pw_uid) {
75 openpam_log(PAM_LOG_LIBDEBUG, "called with non-zero euid: %d",
76 (int)geteuid());
77 RETURNC(PAM_PERM_DENIED);
78 }
79 scred = calloc(1, sizeof *scred);
80 if (scred == NULL)
81 RETURNC(PAM_BUF_ERR);
82 scred->euid = geteuid();
83 scred->egid = getegid();
84 r = getgroups(NGROUPS_MAX, scred->groups);
85 if (r < 0) {
86 FREE(scred);
87 RETURNC(PAM_SYSTEM_ERR);
88 }
89 scred->ngroups = r;
90 r = pam_set_data(pamh, PAM_SAVED_CRED, scred, &openpam_free_data);
91 if (r != PAM_SUCCESS) {
92 FREE(scred);
93 RETURNC(r);
94 }
95 if (geteuid() == pwd->pw_uid)
96 RETURNC(PAM_SUCCESS);
97 if (initgroups(pwd->pw_name, pwd->pw_gid) < 0 ||
98 setegid(pwd->pw_gid) < 0 || seteuid(pwd->pw_uid) < 0) {
99 openpam_restore_cred(pamh);
100 RETURNC(PAM_SYSTEM_ERR);
101 }
102 RETURNC(PAM_SUCCESS);
103 }
104
105 /*
106 * Error codes:
107 *
108 * =pam_set_data
109 * PAM_SYSTEM_ERR
110 * PAM_BUF_ERR
111 * PAM_PERM_DENIED
112 */
113
114 /**
115 * The =openpam_borrow_cred function saves the current credentials and
116 * switches to those of the user specified by its =pwd argument.
117 * The affected credentials are the effective UID, the effective GID, and
118 * the group access list.
119 * The original credentials can be restored using =openpam_restore_cred.
120 *
121 * >setegid 2
122 * >seteuid 2
123 * >setgroups 2
124 */
125