security.mac.portacl.autoport_exempt
This sysctl exempts to bind port '0' as long as IP_PORTRANGELOW hasn't
been set on the socket. This is quite useful as it allows applications
to use automatic binding without adding overly broad rules for the
binding of port 0. This sysctl defaults to enabled.
This is a slight variation on the patch submitted by the contributor.
MFC after: 2 weeks
Submitted by: Michal Mertl <mime at traveller dot cz>
the sx lock was used previously because we might sleep allocating
additional memory by using auto-extending sbufs. However, we no longer
do this, instead retaining the user-submitted rule string, so mutexes
can be used instead. Annotate the reason for not using the sbuf-related
rule-to-string code with a comment.
Switch to using TAILQ_CONCAT() instead of manual list copying, as it's
O(1), reducing the rule replacement step under the mutex from O(2N) to
O(2).
Remove now uneeded vnode-related includes.
MFC after: 2 weeks
permit users and groups to bind ports for TCP or UDP, and is intended
to be combined with the recently committed support for
net.inet.ip.portrange.reservedhigh. The policy is twiddled using
sysctl(8). To use this module, you will need to compile in MAC
support, and probably set reservedhigh to 0, then twiddle
security.mac.portacl.rules to set things as desired. This policy
module only restricts ports explicitly bound using bind(), not
implicitly bound ports where the port number is selected by the
IP stack. It appears to work properly in my local configuration,
but needs more broad testing.
A sample policy might be:
# sysctl security.mac.portacl.rules="uid:425:tcp:80,uid:425:tcp:79"
This permits uid 425 to bind TCP sockets to ports 79 and 80. Currently
no distinction is made for incoming vs. outgoing ports with TCP,
although that would probably be easy to add.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
