1/*-
2 * Copyright (c) 1999-2002, 2007 Robert N. M. Watson
3 * Copyright (c) 2001-2002 Networks Associates Technology, Inc.
4 * Copyright (c) 2006 SPARTA, Inc.
5 * All rights reserved.
6 *
7 * This software was developed by Robert Watson for the TrustedBSD Project.
8 *
9 * This software was developed for the FreeBSD Project in part by Network
10 * Associates Laboratories, the Security Research Division of Network
11 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
12 * as part of the DARPA CHATS research program.
13 *
14 * This software was enhanced by SPARTA ISSO under SPAWAR contract
15 * N66001-04-C-6019 ("SEFOS").
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
19 * are met:
20 * 1. Redistributions of source code must retain the above copyright
21 *    notice, this list of conditions and the following disclaimer.
22 * 2. Redistributions in binary form must reproduce the above copyright
23 *    notice, this list of conditions and the following disclaimer in the
24 *    documentation and/or other materials provided with the distribution.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * $FreeBSD$
39 */
40
41/*
42 * Developed by the TrustedBSD Project.
43 *
44 * Prevent processes owned by a particular uid from seeing various transient
45 * kernel objects associated with other uids.
46 */
47
48#include <sys/param.h>
49#include <sys/kernel.h>
50#include <sys/module.h>
51#include <sys/priv.h>
52#include <sys/proc.h>
53#include <sys/systm.h>
54#include <sys/socket.h>
55#include <sys/socketvar.h>
56#include <sys/sysctl.h>
57
58#include <net/route.h>
59#include <netinet/in.h>
60#include <netinet/in_pcb.h>
61
62#include <security/mac/mac_policy.h>
63
64SYSCTL_DECL(_security_mac);
65
66static SYSCTL_NODE(_security_mac, OID_AUTO, seeotheruids, CTLFLAG_RW, 0,
67    "TrustedBSD mac_seeotheruids policy controls");
68
69static int	seeotheruids_enabled = 1;
70SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, enabled, CTLFLAG_RW,
71    &seeotheruids_enabled, 0, "Enforce seeotheruids policy");
72
73/*
74 * Exception: allow credentials to be aware of other credentials with the
75 * same primary gid.
76 */
77static int	primarygroup_enabled = 0;
78SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, primarygroup_enabled,
79    CTLFLAG_RW, &primarygroup_enabled, 0, "Make an exception for credentials "
80    "with the same real primary group id");
81
82/*
83 * Exception: allow the root user to be aware of other credentials by virtue
84 * of privilege.
85 */
86static int	suser_privileged = 1;
87SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, suser_privileged,
88    CTLFLAG_RW, &suser_privileged, 0, "Make an exception for superuser");
89
90/*
91 * Exception: allow processes with a specific gid to be exempt from the
92 * policy.  One sysctl enables this functionality; the other sets the
93 * exempt gid.
94 */
95static int	specificgid_enabled = 0;
96SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, specificgid_enabled,
97    CTLFLAG_RW, &specificgid_enabled, 0, "Make an exception for credentials "
98    "with a specific gid as their real primary group id or group set");
99
100static gid_t	specificgid = 0;
101SYSCTL_UINT(_security_mac_seeotheruids, OID_AUTO, specificgid, CTLFLAG_RW,
102    &specificgid, 0, "Specific gid to be exempt from seeotheruids policy");
103
104static int
105seeotheruids_check(struct ucred *cr1, struct ucred *cr2)
106{
107
108	if (!seeotheruids_enabled)
109		return (0);
110
111	if (primarygroup_enabled) {
112		if (cr1->cr_rgid == cr2->cr_rgid)
113			return (0);
114	}
115
116	if (specificgid_enabled) {
117		if (cr1->cr_rgid == specificgid ||
118		    groupmember(specificgid, cr1))
119			return (0);
120	}
121
122	if (cr1->cr_ruid == cr2->cr_ruid)
123		return (0);
124
125	if (suser_privileged) {
126		if (priv_check_cred(cr1, PRIV_SEEOTHERUIDS, 0) == 0)
127			return (0);
128	}
129
130	return (ESRCH);
131}
132
133static int
134seeotheruids_proc_check_debug(struct ucred *cred, struct proc *p)
135{
136
137	return (seeotheruids_check(cred, p->p_ucred));
138}
139
140static int
141seeotheruids_proc_check_sched(struct ucred *cred, struct proc *p)
142{
143
144	return (seeotheruids_check(cred, p->p_ucred));
145}
146
147static int
148seeotheruids_proc_check_signal(struct ucred *cred, struct proc *p,
149    int signum)
150{
151
152	return (seeotheruids_check(cred, p->p_ucred));
153}
154
155static int
156seeotheruids_cred_check_visible(struct ucred *cr1, struct ucred *cr2)
157{
158
159	return (seeotheruids_check(cr1, cr2));
160}
161
162static int
163seeotheruids_inpcb_check_visible(struct ucred *cred, struct inpcb *inp,
164    struct label *inplabel)
165{
166
167	return (seeotheruids_check(cred, inp->inp_cred));
168}
169
170static int
171seeotheruids_socket_check_visible(struct ucred *cred, struct socket *so,
172    struct label *solabel)
173{
174
175	return (seeotheruids_check(cred, so->so_cred));
176}
177
178static struct mac_policy_ops seeotheruids_ops =
179{
180	.mpo_proc_check_debug = seeotheruids_proc_check_debug,
181	.mpo_proc_check_sched = seeotheruids_proc_check_sched,
182	.mpo_proc_check_signal = seeotheruids_proc_check_signal,
183	.mpo_cred_check_visible = seeotheruids_cred_check_visible,
184	.mpo_inpcb_check_visible = seeotheruids_inpcb_check_visible,
185	.mpo_socket_check_visible = seeotheruids_socket_check_visible,
186};
187
188MAC_POLICY_SET(&seeotheruids_ops, mac_seeotheruids,
189    "TrustedBSD MAC/seeotheruids", MPC_LOADTIME_FLAG_UNLOADOK, NULL);
190