freebsd-skq/sys/security/mac/mac_priv.c

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Add a new priv(9) kernel interface for checking the availability of privilege for threads and credentials. Unlike the existing suser(9) interface, priv(9) exposes a named privilege identifier to the privilege checking code, allowing more complex policies regarding the granting of privilege to be expressed. Two interfaces are provided, replacing the existing suser(9) interface: suser(td) -> priv_check(td, priv) suser_cred(cred, flags) -> priv_check_cred(cred, priv, flags) A comprehensive list of currently available kernel privileges may be found in priv.h. New privileges are easily added as required, but the comments on adding privileges found in priv.h and priv(9) should be read before doing so. The new privilege interface exposed sufficient information to the privilege checking routine that it will now be possible for jail to determine whether a particular privilege is granted in the check routine, rather than relying on hints from the calling context via the SUSER_ALLOWJAIL flag. For now, the flag is maintained, but a new jail check function, prison_priv_check(), is exposed from kern_jail.c and used by the privilege check routine to determine if the privilege is permitted in jail. As a result, a centralized list of privileges permitted in jail is now present in kern_jail.c. The MAC Framework is now also able to instrument privilege checks, both to deny privileges otherwise granted (mac_priv_check()), and to grant privileges otherwise denied (mac_priv_grant()), permitting MAC Policy modules to implement privilege models, as well as control a much broader range of system behavior in order to constrain processes running with root privilege. The suser() and suser_cred() functions remain implemented, now in terms of priv_check() and the PRIV_ROOT privilege, for use during the transition and possibly continuing use by third party kernel modules that have not been updated. The PRIV_DRIVER privilege exists to allow device drivers to check privilege without adopting a more specific privilege identifier. This change does not modify the actual security policy, rather, it modifies the interface for privilege checks so changes to the security policy become more feasible. Sponsored by: nCircle Network Security, Inc. Obtained from: TrustedBSD Project Discussed on: arch@ Reviewed (at least in part) by: mlaier, jmg, pjd, bde, ceri, Alex Lyashkov <umka at sevcity dot net>, Skip Ford <skip dot ford at verizon dot net>, Antoine Brodin <antoine dot brodin at laposte dot net>
2006-11-06 13:37:19 +00:00
/*-
* 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.
*
* $FreeBSD$
*/
/*
* MAC checks for system privileges.
*/
#include "opt_mac.h"
#include <sys/param.h>
#include <sys/priv.h>
#include <sys/module.h>
#include <security/mac/mac_framework.h>
#include <security/mac/mac_internal.h>
#include <security/mac/mac_policy.h>
Add a new priv(9) kernel interface for checking the availability of privilege for threads and credentials. Unlike the existing suser(9) interface, priv(9) exposes a named privilege identifier to the privilege checking code, allowing more complex policies regarding the granting of privilege to be expressed. Two interfaces are provided, replacing the existing suser(9) interface: suser(td) -> priv_check(td, priv) suser_cred(cred, flags) -> priv_check_cred(cred, priv, flags) A comprehensive list of currently available kernel privileges may be found in priv.h. New privileges are easily added as required, but the comments on adding privileges found in priv.h and priv(9) should be read before doing so. The new privilege interface exposed sufficient information to the privilege checking routine that it will now be possible for jail to determine whether a particular privilege is granted in the check routine, rather than relying on hints from the calling context via the SUSER_ALLOWJAIL flag. For now, the flag is maintained, but a new jail check function, prison_priv_check(), is exposed from kern_jail.c and used by the privilege check routine to determine if the privilege is permitted in jail. As a result, a centralized list of privileges permitted in jail is now present in kern_jail.c. The MAC Framework is now also able to instrument privilege checks, both to deny privileges otherwise granted (mac_priv_check()), and to grant privileges otherwise denied (mac_priv_grant()), permitting MAC Policy modules to implement privilege models, as well as control a much broader range of system behavior in order to constrain processes running with root privilege. The suser() and suser_cred() functions remain implemented, now in terms of priv_check() and the PRIV_ROOT privilege, for use during the transition and possibly continuing use by third party kernel modules that have not been updated. The PRIV_DRIVER privilege exists to allow device drivers to check privilege without adopting a more specific privilege identifier. This change does not modify the actual security policy, rather, it modifies the interface for privilege checks so changes to the security policy become more feasible. Sponsored by: nCircle Network Security, Inc. Obtained from: TrustedBSD Project Discussed on: arch@ Reviewed (at least in part) by: mlaier, jmg, pjd, bde, ceri, Alex Lyashkov <umka at sevcity dot net>, Skip Ford <skip dot ford at verizon dot net>, Antoine Brodin <antoine dot brodin at laposte dot net>
2006-11-06 13:37:19 +00:00
/*
* The MAC Framework interacts with kernel privilege checks in two ways: it
* may restrict the granting of privilege to a subject, and it may grant
* additional privileges to the subject. Policies may implement none, one,
* or both of these entry points. Restriction of privilege by any policy
* always overrides granting of privilege by any policy or other privilege
* mechanism. See kern_priv.c:priv_check_cred() for details of the
* composition.
*/
/*
* Restrict access to a privilege for a credential. Return failure if any
* policy denies access.
*/
Add a new priv(9) kernel interface for checking the availability of privilege for threads and credentials. Unlike the existing suser(9) interface, priv(9) exposes a named privilege identifier to the privilege checking code, allowing more complex policies regarding the granting of privilege to be expressed. Two interfaces are provided, replacing the existing suser(9) interface: suser(td) -> priv_check(td, priv) suser_cred(cred, flags) -> priv_check_cred(cred, priv, flags) A comprehensive list of currently available kernel privileges may be found in priv.h. New privileges are easily added as required, but the comments on adding privileges found in priv.h and priv(9) should be read before doing so. The new privilege interface exposed sufficient information to the privilege checking routine that it will now be possible for jail to determine whether a particular privilege is granted in the check routine, rather than relying on hints from the calling context via the SUSER_ALLOWJAIL flag. For now, the flag is maintained, but a new jail check function, prison_priv_check(), is exposed from kern_jail.c and used by the privilege check routine to determine if the privilege is permitted in jail. As a result, a centralized list of privileges permitted in jail is now present in kern_jail.c. The MAC Framework is now also able to instrument privilege checks, both to deny privileges otherwise granted (mac_priv_check()), and to grant privileges otherwise denied (mac_priv_grant()), permitting MAC Policy modules to implement privilege models, as well as control a much broader range of system behavior in order to constrain processes running with root privilege. The suser() and suser_cred() functions remain implemented, now in terms of priv_check() and the PRIV_ROOT privilege, for use during the transition and possibly continuing use by third party kernel modules that have not been updated. The PRIV_DRIVER privilege exists to allow device drivers to check privilege without adopting a more specific privilege identifier. This change does not modify the actual security policy, rather, it modifies the interface for privilege checks so changes to the security policy become more feasible. Sponsored by: nCircle Network Security, Inc. Obtained from: TrustedBSD Project Discussed on: arch@ Reviewed (at least in part) by: mlaier, jmg, pjd, bde, ceri, Alex Lyashkov <umka at sevcity dot net>, Skip Ford <skip dot ford at verizon dot net>, Antoine Brodin <antoine dot brodin at laposte dot net>
2006-11-06 13:37:19 +00:00
int
mac_priv_check(struct ucred *cred, int priv)
{
int error;
MAC_CHECK(priv_check, cred, priv);
return (error);
}
/*
* Grant access to a privilege for a credential. Return success if any
* policy grants access.
*/
Add a new priv(9) kernel interface for checking the availability of privilege for threads and credentials. Unlike the existing suser(9) interface, priv(9) exposes a named privilege identifier to the privilege checking code, allowing more complex policies regarding the granting of privilege to be expressed. Two interfaces are provided, replacing the existing suser(9) interface: suser(td) -> priv_check(td, priv) suser_cred(cred, flags) -> priv_check_cred(cred, priv, flags) A comprehensive list of currently available kernel privileges may be found in priv.h. New privileges are easily added as required, but the comments on adding privileges found in priv.h and priv(9) should be read before doing so. The new privilege interface exposed sufficient information to the privilege checking routine that it will now be possible for jail to determine whether a particular privilege is granted in the check routine, rather than relying on hints from the calling context via the SUSER_ALLOWJAIL flag. For now, the flag is maintained, but a new jail check function, prison_priv_check(), is exposed from kern_jail.c and used by the privilege check routine to determine if the privilege is permitted in jail. As a result, a centralized list of privileges permitted in jail is now present in kern_jail.c. The MAC Framework is now also able to instrument privilege checks, both to deny privileges otherwise granted (mac_priv_check()), and to grant privileges otherwise denied (mac_priv_grant()), permitting MAC Policy modules to implement privilege models, as well as control a much broader range of system behavior in order to constrain processes running with root privilege. The suser() and suser_cred() functions remain implemented, now in terms of priv_check() and the PRIV_ROOT privilege, for use during the transition and possibly continuing use by third party kernel modules that have not been updated. The PRIV_DRIVER privilege exists to allow device drivers to check privilege without adopting a more specific privilege identifier. This change does not modify the actual security policy, rather, it modifies the interface for privilege checks so changes to the security policy become more feasible. Sponsored by: nCircle Network Security, Inc. Obtained from: TrustedBSD Project Discussed on: arch@ Reviewed (at least in part) by: mlaier, jmg, pjd, bde, ceri, Alex Lyashkov <umka at sevcity dot net>, Skip Ford <skip dot ford at verizon dot net>, Antoine Brodin <antoine dot brodin at laposte dot net>
2006-11-06 13:37:19 +00:00
int
mac_priv_grant(struct ucred *cred, int priv)
{
int error;
MAC_GRANT(priv_grant, cred, priv);
return (error);
}