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/socket.h>
51 #include <sys/socketvar.h>
52 #include <sys/sysctl.h>
53
54 #include <net/route.h>
55 #include <netinet/in.h>
56 #include <netinet/in_pcb.h>
57
58 #include <security/mac/mac_policy.h>
59
60 SYSCTL_DECL(_security_mac);
61
62 SYSCTL_NODE(_security_mac, OID_AUTO, seeotheruids, CTLFLAG_RW, 0,
63 "TrustedBSD mac_seeotheruids policy controls");
64
65 static int seeotheruids_enabled = 1;
66 SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, enabled, CTLFLAG_RW,
67 &seeotheruids_enabled, 0, "Enforce seeotheruids policy");
68
69 /*
70 * Exception: allow credentials to be aware of other credentials with the
71 * same primary gid.
72 */
73 static int primarygroup_enabled = 0;
74 SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, primarygroup_enabled,
75 CTLFLAG_RW, &primarygroup_enabled, 0, "Make an exception for credentials "
76 "with the same real primary group id");
77
78 /*
79 * Exception: allow the root user to be aware of other credentials by virtue
80 * of privilege.
81 */
82 static int suser_privileged = 1;
83 SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, suser_privileged,
84 CTLFLAG_RW, &suser_privileged, 0, "Make an exception for superuser");
85
86 /*
87 * Exception: allow processes with a specific gid to be exempt from the
88 * policy. One sysctl enables this functionality; the other sets the
89 * exempt gid.
90 */
91 static int specificgid_enabled = 0;
92 SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, specificgid_enabled,
93 CTLFLAG_RW, &specificgid_enabled, 0, "Make an exception for credentials "
94 "with a specific gid as their real primary group id or group set");
95
96 static gid_t specificgid = 0;
97 SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, specificgid, CTLFLAG_RW,
98 &specificgid, 0, "Specific gid to be exempt from seeotheruids policy");
99
100 static int
101 seeotheruids_check(struct ucred *cr1, struct ucred *cr2)
102 {
103
104 if (!seeotheruids_enabled)
105 return (0);
106
107 if (primarygroup_enabled) {
108 if (cr1->cr_rgid == cr2->cr_rgid)
109 return (0);
110 }
111
112 if (specificgid_enabled) {
113 if (cr1->cr_rgid == specificgid ||
114 groupmember(specificgid, cr1))
115 return (0);
116 }
117
118 if (cr1->cr_ruid == cr2->cr_ruid)
119 return (0);
120
121 if (suser_privileged) {
122 if (priv_check_cred(cr1, PRIV_SEEOTHERUIDS, 0) == 0)
123 return (0);
124 }
125
126 return (ESRCH);
127 }
128
129 static int
130 seeotheruids_check_cred_visible(struct ucred *cr1, struct ucred *cr2)
131 {
132
133 return (seeotheruids_check(cr1, cr2));
134 }
135
136 static int
137 seeotheruids_check_inpcb_visible(struct ucred *cred, struct inpcb *inp,
138 struct label *inplabel)
139 {
140
141 return (seeotheruids_check(cred, inp->inp_cred));
142 }
143
144 static int
145 seeotheruids_check_proc_signal(struct ucred *cred, struct proc *p,
146 int signum)
147 {
148
149 return (seeotheruids_check(cred, p->p_ucred));
150 }
151
152 static int
153 seeotheruids_check_proc_sched(struct ucred *cred, struct proc *p)
154 {
155
156 return (seeotheruids_check(cred, p->p_ucred));
157 }
158
159 static int
160 seeotheruids_check_proc_debug(struct ucred *cred, struct proc *p)
161 {
162
163 return (seeotheruids_check(cred, p->p_ucred));
164 }
165
166 static int
167 seeotheruids_check_socket_visible(struct ucred *cred, struct socket *so,
168 struct label *solabel)
169 {
170
171 return (seeotheruids_check(cred, so->so_cred));
172 }
173
174 static struct mac_policy_ops seeotheruids_ops =
175 {
176 .mpo_check_cred_visible = seeotheruids_check_cred_visible,
177 .mpo_check_inpcb_visible = seeotheruids_check_inpcb_visible,
178 .mpo_check_proc_debug = seeotheruids_check_proc_debug,
179 .mpo_check_proc_sched = seeotheruids_check_proc_sched,
180 .mpo_check_proc_signal = seeotheruids_check_proc_signal,
181 .mpo_check_socket_visible = seeotheruids_check_socket_visible,
182 };
183
184 MAC_POLICY_SET(&seeotheruids_ops, mac_seeotheruids,
185 "TrustedBSD MAC/seeotheruids", MPC_LOADTIME_FLAG_UNLOADOK, NULL);
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