All rights reserved.
This software was developed for the FreeBSD Project by Chris Costello
at Safeport Network Services and Network Associates 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.
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$FreeBSD: releng/11.0/share/man/man4/mac_portacl.4 213573 2010-10-08 12:40:16Z uqs $
.Dd December 9, 2004 .Dt MAC_PORTACL 4 .Os .Sh NAME .Nm mac_portacl .Nd "network port access control policy" .Sh SYNOPSIS To compile the port access control policy into your kernel, place the following lines in your kernel configuration file: d -ragged -offset indent .Cd "options MAC" .Cd "options MAC_PORTACL" .Ed
p Alternately, to load the port access control policy module at boot time, place the following line in your kernel configuration file: d -ragged -offset indent .Cd "options MAC" .Ed
p and in .Xr loader.conf 5 :
p .Dl "mac_portacl_load=""YES""" .Sh DESCRIPTION The .Nm policy allows administrators to administratively limit binding to local .Tn UDP and .Tn TCP ports via the .Xr sysctl 8 interface.
p In order to enable the .Nm policy, MAC policy must be enforced on sockets (see .Xr mac 4 ) , and the port(s) protected by .Nm must not be included in the range specified by the .Va net.inet.ip.portrange.reservedlow and .Va net.inet.ip.portrange.reservedhigh .Xr sysctl 8 MIBs.
p The .Nm policy only affects ports explicitly bound by a user process (either for a listen/outgoing .Tn TCP socket, or a send/receive .Tn UDP socket). This policy will not limit ports bound implicitly for outgoing connections where the process has not explicitly selected a port: these are automatically selected by the IP stack.
p When .Nm is enabled, it will control binding access to ports up to the port number set in the .Va security.mac.portacl.port_high .Xr sysctl 8 variable. By default, all attempts to bind to .Nm controlled ports will fail if not explicitly allowed by the port access control list, though binding by the superuser will be allowed, if the .Xr sysctl 8 variable .Va security.mac.portacl.suser_exempt is set to a non-zero value. .Ss Runtime Configuration The following .Xr sysctl 8 MIBs are available for fine-tuning the enforcement of this MAC policy. All .Xr sysctl 8 variables, except .Va security.mac.portacl.rules , can also be set as .Xr loader 8 tunables in .Xr loader.conf 5 . l -tag -width indent t Va security.mac.portacl.enabled Enforce the .Nm policy. (Default: 1). t Va security.mac.portacl.port_high The highest port number .Nm will enforce rules for. (Default: 1023). t Va security.mac.portacl.rules The port access control list is specified in the following format:
p .Sm off .D1 Ar idtype : id : protocol : port Op , Ar idtype : id : protocol : port , ... .Sm on l -tag -width ".Ar protocol" t Ar idtype Describes the type of subject match to be performed. Either .Li uid for user ID matching, or .Li gid for group ID matching. t Ar id The user or group ID (depending on .Ar idtype ) allowed to bind to the specified port. f -emphasis NOTE: User and group names are not valid; only the actual ID numbers may be used. .Ef t Ar protocol Describes which protocol this entry applies to. Either .Li tcp or .Li udp are supported. t Ar port Describes which port this entry applies to. f -emphasis NOTE: MAC security policies may not override other security system policies by allowing accesses that they may deny, such as .Va net.inet.ip.portrange.reservedlow / .Va net.inet.ip.portrange.reservedhigh . .Ef If the specified port falls within the range specified, the .Nm entry will not function (i.e., even the specified user/group may not be able to bind to the specified port). .El t Va security.mac.portacl.suser_exempt Allow superuser (i.e., root) to bind to all .Nm protected ports, even if the port access control list does not explicitly allow this. (Default: 1). t Va security.mac.portacl.autoport_exempt Allow applications to use automatic binding to port 0. Applications use port 0 as a request for automatic port allocation when binding an IP address to a socket. This tunable will exempt port 0 allocation from rule checking. (Default: 1). .El .Sh SEE ALSO .Xr mac 3 , .Xr ip 4 , .Xr mac_biba 4 , .Xr mac_bsdextended 4 , .Xr mac_ifoff 4 , .Xr mac_mls 4 , .Xr mac_none 4 , .Xr mac_partition 4 , .Xr mac_seeotheruids 4 , .Xr mac_test 4 , .Xr mac 9 .Sh HISTORY MAC first appeared in .Fx 5.0 and .Nm first appeared in .Fx 5.1 . .Sh AUTHORS This software was contributed to the .Fx Project by NAI Labs, the Security Research Division of Network Associates Inc. under DARPA/SPAWAR contract N66001-01-C-8035
q Dq CBOSS , as part of the DARPA CHATS research program.