2 * Copyright (c) 2006 nCircle Network Security, Inc.
5 * This software was developed by Robert N. M. Watson for the TrustedBSD
6 * Project under contract to nCircle Network Security, Inc.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR, NCIRCLE NETWORK SECURITY,
21 * INC., OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
23 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
24 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
25 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
26 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
27 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 #include <sys/param.h>
36 #include <sys/kernel.h>
39 #include <sys/sysctl.h>
40 #include <sys/systm.h>
42 #include <security/mac/mac_framework.h>
45 * `suser_enabled' (which can be set by the security.bsd.suser_enabled
46 * sysctl) determines whether the system 'super-user' policy is in effect. If
47 * it is nonzero, an effective uid of 0 connotes special privilege,
48 * overriding many mandatory and discretionary protections. If it is zero,
49 * uid 0 is offered no special privilege in the kernel security policy.
50 * Setting it to zero may seriously impact the functionality of many existing
51 * userland programs, and should not be done without careful consideration of
54 int suser_enabled = 1;
55 SYSCTL_INT(_security_bsd, OID_AUTO, suser_enabled, CTLFLAG_RW,
56 &suser_enabled, 0, "processes with uid 0 have privilege");
57 TUNABLE_INT("security.bsd.suser_enabled", &suser_enabled);
60 * Check a credential for privilege. Lots of good reasons to deny privilege;
61 * only a few to grant it.
64 priv_check_cred(struct ucred *cred, int priv, int flags)
68 KASSERT(PRIV_VALID(priv), ("priv_check_cred: invalid privilege %d",
72 error = mac_priv_check(cred, priv);
78 * Jail policy will restrict certain privileges that may otherwise be
81 * While debugging the transition from SUSER_ALLOWJAIL to Jail being
82 * aware of specific privileges, perform run-time checking that the
83 * two versions of the policy align. This assertion will go away
84 * once the SUSER_ALLOWJAIL flag has gone away.
86 error = prison_priv_check(cred, priv);
88 KASSERT(!jailed(cred) || error == ((flags & SUSER_ALLOWJAIL) ? 0 :
89 EPERM), ("priv_check_cred: prison_priv_check %d but flags %s",
90 error, flags & SUSER_ALLOWJAIL ? "allowjail" : "!allowjail"));
96 * Having determined if privilege is restricted by various policies,
97 * now determine if privilege is granted. For now, we allow
98 * short-circuit boolean evaluation, so may not call all policies.
101 * Superuser policy grants privilege based on the effective (or in
102 * certain edge cases, real) uid being 0. We allow the policy to be
103 * globally disabled, although this is currently of limited utility.
106 if (flags & SUSER_RUID) {
107 if (cred->cr_ruid == 0)
110 if (cred->cr_uid == 0)
116 * Now check with MAC, if enabled, to see if a policy module grants
120 if (mac_priv_grant(cred, priv) == 0)
127 priv_check(struct thread *td, int priv)
130 KASSERT(td == curthread, ("priv_check: td != curthread"));
132 return (priv_check_cred(td->td_ucred, priv, 0));
136 * Historical suser() wrapper functions, which now simply request PRIV_ROOT.
137 * These will be removed in the near future, and exist solely because
138 * the kernel and modules are not yet fully adapted to the new model.
141 suser_cred(struct ucred *cred, int flags)
144 return (priv_check_cred(cred, PRIV_ROOT, flags));
148 suser(struct thread *td)
151 KASSERT(td == curthread, ("suser: td != curthread"));
153 return (suser_cred(td->td_ucred, 0));