1 /*-
2 * Copyright (c) 1999-2002, 2007 Robert N. M. Watson
3 * Copyright (c) 2001-2002 Networks Associates Technology, Inc.
4 * All rights reserved.
5 *
6 * This software was developed by Robert Watson for the TrustedBSD Project.
7 *
8 * This software was developed for the FreeBSD Project in part by Network
9 * Associates Laboratories, the Security Research Division of Network
10 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
11 * 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 *
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * $FreeBSD$
35 */
36
37 /*
38 * Developed by the TrustedBSD Project.
39 *
40 * Prevent processes owned by a particular uid from seeing various transient
41 * kernel objects associated with other uids.
42 */
43
44 #include <sys/param.h>
45 #include <sys/kernel.h>
46 #include <sys/module.h>
47 #include <sys/priv.h>
48 #include <sys/proc.h>
49 #include <sys/systm.h>
50 #include <sys/socketvar.h>
51 #include <sys/sysctl.h>
52
53 #include <security/mac/mac_policy.h>
54
55 SYSCTL_DECL(_security_mac);
56
57 SYSCTL_NODE(_security_mac, OID_AUTO, seeotheruids, CTLFLAG_RW, 0,
58 "TrustedBSD mac_seeotheruids policy controls");
59
60 static int mac_seeotheruids_enabled = 1;
61 SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, enabled, CTLFLAG_RW,
62 &mac_seeotheruids_enabled, 0, "Enforce seeotheruids policy");
63
64 /*
65 * Exception: allow credentials to be aware of other credentials with the
66 * same primary gid.
67 */
68 static int primarygroup_enabled = 0;
69 SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, primarygroup_enabled,
70 CTLFLAG_RW, &primarygroup_enabled, 0, "Make an exception for credentials "
71 "with the same real primary group id");
72
73 /*
74 * Exception: allow the root user to be aware of other credentials by virtue
75 * of privilege.
76 */
77 static int suser_privileged = 1;
78 SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, suser_privileged,
79 CTLFLAG_RW, &suser_privileged, 0, "Make an exception for superuser");
80
81 /*
82 * Exception: allow processes with a specific gid to be exempt from the
83 * policy. One sysctl enables this functionality; the other sets the
84 * exempt gid.
85 */
86 static int specificgid_enabled = 0;
87 SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, specificgid_enabled,
88 CTLFLAG_RW, &specificgid_enabled, 0, "Make an exception for credentials "
89 "with a specific gid as their real primary group id or group set");
90
91 static gid_t specificgid = 0;
92 SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, specificgid, CTLFLAG_RW,
93 &specificgid, 0, "Specific gid to be exempt from seeotheruids policy");
94
95 static int
96 mac_seeotheruids_check(struct ucred *cr1, struct ucred *cr2)
97 {
98
99 if (!mac_seeotheruids_enabled)
100 return (0);
101
102 if (primarygroup_enabled) {
103 if (cr1->cr_rgid == cr2->cr_rgid)
104 return (0);
105 }
106
107 if (specificgid_enabled) {
108 if (cr1->cr_rgid == specificgid ||
109 groupmember(specificgid, cr1))
110 return (0);
111 }
112
113 if (cr1->cr_ruid == cr2->cr_ruid)
114 return (0);
115
116 if (suser_privileged) {
117 if (priv_check_cred(cr1, PRIV_SEEOTHERUIDS, 0) == 0)
118 return (0);
119 }
120
121 return (ESRCH);
122 }
123
124 static int
125 mac_seeotheruids_check_cred_visible(struct ucred *cr1, struct ucred *cr2)
126 {
127
128 return (mac_seeotheruids_check(cr1, cr2));
129 }
130
131 static int
132 mac_seeotheruids_check_proc_signal(struct ucred *cred, struct proc *p,
133 int signum)
134 {
135
136 return (mac_seeotheruids_check(cred, p->p_ucred));
137 }
138
139 static int
140 mac_seeotheruids_check_proc_sched(struct ucred *cred, struct proc *p)
141 {
142
143 return (mac_seeotheruids_check(cred, p->p_ucred));
144 }
145
146 static int
147 mac_seeotheruids_check_proc_debug(struct ucred *cred, struct proc *p)
148 {
149
150 return (mac_seeotheruids_check(cred, p->p_ucred));
151 }
152
153 static int
154 mac_seeotheruids_check_socket_visible(struct ucred *cred, struct socket *so,
155 struct label *solabel)
156 {
157
158 return (mac_seeotheruids_check(cred, so->so_cred));
159 }
160
161 static struct mac_policy_ops mac_seeotheruids_ops =
162 {
163 .mpo_check_cred_visible = mac_seeotheruids_check_cred_visible,
164 .mpo_check_proc_debug = mac_seeotheruids_check_proc_debug,
165 .mpo_check_proc_sched = mac_seeotheruids_check_proc_sched,
166 .mpo_check_proc_signal = mac_seeotheruids_check_proc_signal,
167 .mpo_check_socket_visible = mac_seeotheruids_check_socket_visible,
168 };
169
170 MAC_POLICY_SET(&mac_seeotheruids_ops, mac_seeotheruids,
171 "TrustedBSD MAC/seeotheruids", MPC_LOADTIME_FLAG_UNLOADOK, NULL);
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