2 * Copyright (c) 2006 nCircle Network Security, Inc.
3 * Copyright (c) 2009 Robert N. M. Watson
6 * This software was developed by Robert N. M. Watson for the TrustedBSD
7 * Project under contract to nCircle Network Security, Inc.
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
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.
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.
31 #include "opt_kdtrace.h"
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
36 #include <sys/param.h>
38 #include <sys/kernel.h>
42 #include <sys/sysctl.h>
43 #include <sys/systm.h>
45 #include <security/mac/mac_framework.h>
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
57 static int suser_enabled = 1;
58 SYSCTL_INT(_security_bsd, OID_AUTO, suser_enabled, CTLFLAG_RW,
59 &suser_enabled, 0, "processes with uid 0 have privilege");
60 TUNABLE_INT("security.bsd.suser_enabled", &suser_enabled);
62 SDT_PROVIDER_DEFINE(priv);
63 SDT_PROBE_DEFINE1(priv, kernel, priv_check, priv_ok, priv-ok, "int");
64 SDT_PROBE_DEFINE1(priv, kernel, priv_check, priv_err, priv-err, "int");
67 * Check a credential for privilege. Lots of good reasons to deny privilege;
68 * only a few to grant it.
71 priv_check_cred(struct ucred *cred, int priv, int flags)
75 KASSERT(PRIV_VALID(priv), ("priv_check_cred: invalid privilege %d",
79 * We first evaluate policies that may deny the granting of
80 * privilege unilaterally.
83 error = mac_priv_check(cred, priv);
89 * Jail policy will restrict certain privileges that may otherwise be
92 error = prison_priv_check(cred, priv);
97 * Having determined if privilege is restricted by various policies,
98 * now determine if privilege is granted. At this point, any policy
99 * may grant privilege. For now, we allow short-circuit boolean
100 * evaluation, so may not call all policies. Perhaps we should.
102 * Superuser policy grants privilege based on the effective (or in
103 * the case of specific privileges, real) uid being 0. We allow the
104 * superuser policy to be globally disabled, although this is
105 * currenty of limited utility.
111 case PRIV_PROC_LIMIT:
112 if (cred->cr_ruid == 0) {
119 if (cred->cr_uid == 0) {
128 * Now check with MAC, if enabled, to see if a policy module grants
132 if (mac_priv_grant(cred, priv) == 0) {
139 * The default is deny, so if no policies have granted it, reject
140 * with a privilege error here.
145 SDT_PROBE(priv, kernel, priv_check, priv_err, priv, 0, 0, 0,
148 SDT_PROBE(priv, kernel, priv_check, priv_ok, priv, 0, 0, 0,
155 priv_check(struct thread *td, int priv)
158 KASSERT(td == curthread, ("priv_check: td != curthread"));
160 return (priv_check_cred(td->td_ucred, priv, 0));