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_BSDEXTENDEDAlternately, to load the file system firewall policy module at boot time, place the following line in your kernel configuration file:
options MACand in loader.conf(5):
mac_bsdextended_load="YES"
DESCRIPTION
Themac_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
AUTHPRIVsyslog(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.