freebsd-nq/sys/kern/kern_priv.c
Robert Watson 32f9753cfb Eliminate now-unused SUSER_ALLOWJAIL arguments to priv_check_cred(); in
some cases, move to priv_check() if it was an operation on a thread and
no other flags were present.

Eliminate caller-side jail exception checking (also now-unused); jail
privilege exception code now goes solely in kern_jail.c.

We can't yet eliminate suser() due to some cases in the KAME code where
a privilege check is performed and then used in many different deferred
paths.  Do, however, move those prototypes to priv.h.

Reviewed by:	csjp
Obtained from:	TrustedBSD Project
2007-06-12 00:12:01 +00:00

145 lines
4.4 KiB
C

/*-
* Copyright (c) 2006 nCircle Network Security, Inc.
* All rights reserved.
*
* This software was developed by Robert N. M. Watson for the TrustedBSD
* Project under contract to nCircle Network Security, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR, NCIRCLE NETWORK SECURITY,
* INC., OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $FreeBSD$
*/
#include "opt_mac.h"
#include <sys/param.h>
#include <sys/jail.h>
#include <sys/kernel.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <security/mac/mac_framework.h>
/*
* `suser_enabled' (which can be set by the security.bsd.suser_enabled
* sysctl) determines whether the system 'super-user' policy is in effect. If
* it is nonzero, an effective uid of 0 connotes special privilege,
* overriding many mandatory and discretionary protections. If it is zero,
* uid 0 is offered no special privilege in the kernel security policy.
* Setting it to zero may seriously impact the functionality of many existing
* userland programs, and should not be done without careful consideration of
* the consequences.
*/
int suser_enabled = 1;
SYSCTL_INT(_security_bsd, OID_AUTO, suser_enabled, CTLFLAG_RW,
&suser_enabled, 0, "processes with uid 0 have privilege");
TUNABLE_INT("security.bsd.suser_enabled", &suser_enabled);
/*
* Check a credential for privilege. Lots of good reasons to deny privilege;
* only a few to grant it.
*/
int
priv_check_cred(struct ucred *cred, int priv, int flags)
{
int error;
KASSERT(PRIV_VALID(priv), ("priv_check_cred: invalid privilege %d",
priv));
#ifdef MAC
error = mac_priv_check(cred, priv);
if (error)
return (error);
#endif
/*
* Jail policy will restrict certain privileges that may otherwise be
* be granted.
*/
error = prison_priv_check(cred, priv);
if (error)
return (error);
/*
* Having determined if privilege is restricted by various policies,
* now determine if privilege is granted. For now, we allow
* short-circuit boolean evaluation, so may not call all policies.
* Perhaps we should.
*
* Superuser policy grants privilege based on the effective (or in
* certain edge cases, real) uid being 0. We allow the policy to be
* globally disabled, although this is currently of limited utility.
*/
if (suser_enabled) {
if (flags & SUSER_RUID) {
if (cred->cr_ruid == 0)
return (0);
} else {
if (cred->cr_uid == 0)
return (0);
}
}
/*
* Now check with MAC, if enabled, to see if a policy module grants
* privilege.
*/
#ifdef MAC
if (mac_priv_grant(cred, priv) == 0)
return (0);
#endif
return (EPERM);
}
int
priv_check(struct thread *td, int priv)
{
KASSERT(td == curthread, ("priv_check: td != curthread"));
return (priv_check_cred(td->td_ucred, priv, 0));
}
/*
* Historical suser() wrapper functions, which now simply request PRIV_ROOT.
* These will be removed in the near future, and exist solely because
* the kernel and modules are not yet fully adapted to the new model.
*/
int
suser_cred(struct ucred *cred, int flags)
{
return (priv_check_cred(cred, PRIV_ROOT, flags));
}
int
suser(struct thread *td)
{
KASSERT(td == curthread, ("suser: td != curthread"));
return (suser_cred(td->td_ucred, 0));
}