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.