NAME
mac_bsdextended - file system firewall policy
SYNOPSIS
To compile the file system firewall policy into your kernel, place the
following lines in your kernel configuration file:
options MAC
options MAC_BSDEXTENDED
Alternately, to load the file system firewall policy module at boot time,
place the following line in your kernel configuration file:
options MAC
and in loader.conf(5):
mac_bsdextended_load="YES"
DESCRIPTION
The mac_bsdextended security policy module provides an interface for the
system administrator to impose mandatory rules regarding users and some
system objects. Rules are uploaded to the module (typically using
ugidfw(8), or some other tool utilizing libugidfw(3)) where they are
stored internally and used to determine whether to allow or deny specific
accesses (see ugidfw(8)).
IMPLEMENTATION NOTES
While the traditional mac(9) entry points are implemented, policy labels
are not used; instead, access control decisions are made by iterating
through the internal list of rules until a rule which denies the
particular access is found, or the end of the list is reached. The
mac_bsdextended policy works similar to ipfw(8) or by using a first match
semantic. This means that not all rules are applied, only the first
matched rule; thus if Rule A allows access and Rule B blocks access, Rule
B will never be applied.
Sysctls
The following sysctls may be used to tweak the behavior of
mac_bsdextended:
security.mac.bsdextended.enabled
Set to zero or one to toggle the policy off or on.
security.mac.bsdextended.rule_count
List the number of defined rules, the maximum rule count is
current set at 256.
security.mac.bsdextended.rule_slots
List the number of rule slots currently being used.
security.mac.bsdextended.firstmatch_enabled
Toggle between the old all rules match functionality and the new
first rule matches functionality. This is enabled by default.
security.mac.bsdextended.logging
Log all access violations via the AUTHPRIV syslog(3) facility.
security.mac.bsdextended.rules
Currently does nothing interesting.
SEE ALSO
libugidfw(3), syslog(3), mac(4), mac_biba(4), mac_ifoff(4), mac_lomac(4),
mac_mls(4), mac_none(4), mac_partition(4), mac_portacl(4),
mac_seeotheruids(4), mac_test(4), ipfw(8), ugidfw(8), mac(9)
HISTORY
The mac_bsdextended policy module first appeared in FreeBSD 5.0 and was
developed by the TrustedBSD Project.
The "match first case" and logging capabilities were later added by Tom
Rhodes 〈trhodes@FreeBSD.org〉.
AUTHORS
This software was contributed to the FreeBSD Project by NAI Labs, the
Security Research Division of Network Associates Inc. under DARPA/SPAWAR
contract N66001-01-C-8035 (“CBOSS”), as part of the DARPA CHATS research
program.