1/*-
2 * Copyright (c) 2006 nCircle Network Security, Inc.
3 * Copyright (c) 2009 Robert N. M. Watson
4 * All rights reserved.
5 *
6 * This software was developed by Robert N. M. Watson for the TrustedBSD
7 * Project under contract to nCircle Network Security, Inc.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR, NCIRCLE NETWORK SECURITY,
22 * INC., OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
24 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
25 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
26 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
27 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
28 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#include "opt_kdtrace.h"
32
33#include <sys/cdefs.h>
| 1/*-
2 * Copyright (c) 2006 nCircle Network Security, Inc.
3 * Copyright (c) 2009 Robert N. M. Watson
4 * All rights reserved.
5 *
6 * This software was developed by Robert N. M. Watson for the TrustedBSD
7 * Project under contract to nCircle Network Security, Inc.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR, NCIRCLE NETWORK SECURITY,
22 * INC., OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
24 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
25 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
26 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
27 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
28 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#include "opt_kdtrace.h"
32
33#include <sys/cdefs.h>
|
34__FBSDID("$FreeBSD: stable/10/sys/kern/kern_priv.c 252855 2013-07-06 00:10:52Z jamie $");
| 34__FBSDID("$FreeBSD: stable/10/sys/kern/kern_priv.c 260817 2014-01-17 10:58:59Z avg $");
|
35
36#include <sys/param.h>
37#include <sys/jail.h>
38#include <sys/kernel.h>
39#include <sys/priv.h>
40#include <sys/proc.h>
41#include <sys/sdt.h>
42#include <sys/sysctl.h>
43#include <sys/systm.h>
44
45#include <security/mac/mac_framework.h>
46
47/*
48 * `suser_enabled' (which can be set by the security.bsd.suser_enabled
49 * sysctl) determines whether the system 'super-user' policy is in effect. If
50 * it is nonzero, an effective uid of 0 connotes special privilege,
51 * overriding many mandatory and discretionary protections. If it is zero,
52 * uid 0 is offered no special privilege in the kernel security policy.
53 * Setting it to zero may seriously impact the functionality of many existing
54 * userland programs, and should not be done without careful consideration of
55 * the consequences.
56 */
57static int suser_enabled = 1;
58SYSCTL_INT(_security_bsd, OID_AUTO, suser_enabled, CTLFLAG_RW,
59 &suser_enabled, 0, "processes with uid 0 have privilege");
60TUNABLE_INT("security.bsd.suser_enabled", &suser_enabled);
61
62static int unprivileged_mlock = 1;
63SYSCTL_INT(_security_bsd, OID_AUTO, unprivileged_mlock, CTLFLAG_RW|CTLFLAG_TUN,
64 &unprivileged_mlock, 0, "Allow non-root users to call mlock(2)");
65TUNABLE_INT("security.bsd.unprivileged_mlock", &unprivileged_mlock);
66
67SDT_PROVIDER_DEFINE(priv);
| 35
36#include <sys/param.h>
37#include <sys/jail.h>
38#include <sys/kernel.h>
39#include <sys/priv.h>
40#include <sys/proc.h>
41#include <sys/sdt.h>
42#include <sys/sysctl.h>
43#include <sys/systm.h>
44
45#include <security/mac/mac_framework.h>
46
47/*
48 * `suser_enabled' (which can be set by the security.bsd.suser_enabled
49 * sysctl) determines whether the system 'super-user' policy is in effect. If
50 * it is nonzero, an effective uid of 0 connotes special privilege,
51 * overriding many mandatory and discretionary protections. If it is zero,
52 * uid 0 is offered no special privilege in the kernel security policy.
53 * Setting it to zero may seriously impact the functionality of many existing
54 * userland programs, and should not be done without careful consideration of
55 * the consequences.
56 */
57static int suser_enabled = 1;
58SYSCTL_INT(_security_bsd, OID_AUTO, suser_enabled, CTLFLAG_RW,
59 &suser_enabled, 0, "processes with uid 0 have privilege");
60TUNABLE_INT("security.bsd.suser_enabled", &suser_enabled);
61
62static int unprivileged_mlock = 1;
63SYSCTL_INT(_security_bsd, OID_AUTO, unprivileged_mlock, CTLFLAG_RW|CTLFLAG_TUN,
64 &unprivileged_mlock, 0, "Allow non-root users to call mlock(2)");
65TUNABLE_INT("security.bsd.unprivileged_mlock", &unprivileged_mlock);
66
67SDT_PROVIDER_DEFINE(priv);
|
68SDT_PROBE_DEFINE1(priv, kernel, priv_check, priv_ok, priv-ok, "int");
69SDT_PROBE_DEFINE1(priv, kernel, priv_check, priv_err, priv-err, "int");
| 68SDT_PROBE_DEFINE1(priv, kernel, priv_check, priv__ok, "int");
69SDT_PROBE_DEFINE1(priv, kernel, priv_check, priv__err, "int");
|
70
71/*
72 * Check a credential for privilege. Lots of good reasons to deny privilege;
73 * only a few to grant it.
74 */
75int
76priv_check_cred(struct ucred *cred, int priv, int flags)
77{
78 int error;
79
80 KASSERT(PRIV_VALID(priv), ("priv_check_cred: invalid privilege %d",
81 priv));
82
83 /*
84 * We first evaluate policies that may deny the granting of
85 * privilege unilaterally.
86 */
87#ifdef MAC
88 error = mac_priv_check(cred, priv);
89 if (error)
90 goto out;
91#endif
92
93 /*
94 * Jail policy will restrict certain privileges that may otherwise be
95 * be granted.
96 */
97 error = prison_priv_check(cred, priv);
98 if (error)
99 goto out;
100
101 if (unprivileged_mlock) {
102 /*
103 * Allow unprivileged users to call mlock(2)/munlock(2) and
104 * mlockall(2)/munlockall(2).
105 */
106 switch (priv) {
107 case PRIV_VM_MLOCK:
108 case PRIV_VM_MUNLOCK:
109 error = 0;
110 goto out;
111 }
112 }
113
114 /*
115 * Having determined if privilege is restricted by various policies,
116 * now determine if privilege is granted. At this point, any policy
117 * may grant privilege. For now, we allow short-circuit boolean
118 * evaluation, so may not call all policies. Perhaps we should.
119 *
120 * Superuser policy grants privilege based on the effective (or in
121 * the case of specific privileges, real) uid being 0. We allow the
122 * superuser policy to be globally disabled, although this is
123 * currenty of limited utility.
124 */
125 if (suser_enabled) {
126 switch (priv) {
127 case PRIV_MAXFILES:
128 case PRIV_MAXPROC:
129 case PRIV_PROC_LIMIT:
130 if (cred->cr_ruid == 0) {
131 error = 0;
132 goto out;
133 }
134 break;
135 default:
136 if (cred->cr_uid == 0) {
137 error = 0;
138 goto out;
139 }
140 break;
141 }
142 }
143
144 /*
145 * Writes to kernel/physical memory are a typical root-only operation,
146 * but non-root users are expected to be able to read it (provided they
147 * have permission to access /dev/[k]mem).
148 */
149 if (priv == PRIV_KMEM_READ) {
150 error = 0;
151 goto out;
152 }
153
154 /*
155 * Now check with MAC, if enabled, to see if a policy module grants
156 * privilege.
157 */
158#ifdef MAC
159 if (mac_priv_grant(cred, priv) == 0) {
160 error = 0;
161 goto out;
162 }
163#endif
164
165 /*
166 * The default is deny, so if no policies have granted it, reject
167 * with a privilege error here.
168 */
169 error = EPERM;
170out:
171 if (error)
| 70
71/*
72 * Check a credential for privilege. Lots of good reasons to deny privilege;
73 * only a few to grant it.
74 */
75int
76priv_check_cred(struct ucred *cred, int priv, int flags)
77{
78 int error;
79
80 KASSERT(PRIV_VALID(priv), ("priv_check_cred: invalid privilege %d",
81 priv));
82
83 /*
84 * We first evaluate policies that may deny the granting of
85 * privilege unilaterally.
86 */
87#ifdef MAC
88 error = mac_priv_check(cred, priv);
89 if (error)
90 goto out;
91#endif
92
93 /*
94 * Jail policy will restrict certain privileges that may otherwise be
95 * be granted.
96 */
97 error = prison_priv_check(cred, priv);
98 if (error)
99 goto out;
100
101 if (unprivileged_mlock) {
102 /*
103 * Allow unprivileged users to call mlock(2)/munlock(2) and
104 * mlockall(2)/munlockall(2).
105 */
106 switch (priv) {
107 case PRIV_VM_MLOCK:
108 case PRIV_VM_MUNLOCK:
109 error = 0;
110 goto out;
111 }
112 }
113
114 /*
115 * Having determined if privilege is restricted by various policies,
116 * now determine if privilege is granted. At this point, any policy
117 * may grant privilege. For now, we allow short-circuit boolean
118 * evaluation, so may not call all policies. Perhaps we should.
119 *
120 * Superuser policy grants privilege based on the effective (or in
121 * the case of specific privileges, real) uid being 0. We allow the
122 * superuser policy to be globally disabled, although this is
123 * currenty of limited utility.
124 */
125 if (suser_enabled) {
126 switch (priv) {
127 case PRIV_MAXFILES:
128 case PRIV_MAXPROC:
129 case PRIV_PROC_LIMIT:
130 if (cred->cr_ruid == 0) {
131 error = 0;
132 goto out;
133 }
134 break;
135 default:
136 if (cred->cr_uid == 0) {
137 error = 0;
138 goto out;
139 }
140 break;
141 }
142 }
143
144 /*
145 * Writes to kernel/physical memory are a typical root-only operation,
146 * but non-root users are expected to be able to read it (provided they
147 * have permission to access /dev/[k]mem).
148 */
149 if (priv == PRIV_KMEM_READ) {
150 error = 0;
151 goto out;
152 }
153
154 /*
155 * Now check with MAC, if enabled, to see if a policy module grants
156 * privilege.
157 */
158#ifdef MAC
159 if (mac_priv_grant(cred, priv) == 0) {
160 error = 0;
161 goto out;
162 }
163#endif
164
165 /*
166 * The default is deny, so if no policies have granted it, reject
167 * with a privilege error here.
168 */
169 error = EPERM;
170out:
171 if (error)
|
172 SDT_PROBE1(priv, kernel, priv_check, priv_err, priv);
| 172 SDT_PROBE1(priv, kernel, priv_check, priv__err, priv);
|
173 else
| 173 else
|
174 SDT_PROBE1(priv, kernel, priv_check, priv_ok, priv);
| 174 SDT_PROBE1(priv, kernel, priv_check, priv__ok, priv);
|
175 return (error);
176}
177
178int
179priv_check(struct thread *td, int priv)
180{
181
182 KASSERT(td == curthread, ("priv_check: td != curthread"));
183
184 return (priv_check_cred(td->td_ucred, priv, 0));
185}
| 175 return (error);
176}
177
178int
179priv_check(struct thread *td, int priv)
180{
181
182 KASSERT(td == curthread, ("priv_check: td != curthread"));
183
184 return (priv_check_cred(td->td_ucred, priv, 0));
185}
|