145 lines
4.4 KiB
C
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));
|
||
|
}
|