Introduce a MAC label reference in 'struct inpcb', which caches

the   MAC label referenced from 'struct socket' in the IPv4 and
IPv6-based protocols.  This permits MAC labels to be checked during
network delivery operations without dereferencing inp->inp_socket
to get to so->so_label, which will eventually avoid our having to
grab the socket lock during delivery at the network layer.

This change introduces 'struct inpcb' as a labeled object to the
MAC Framework, along with the normal circus of entry points:
initialization, creation from socket, destruction, as well as a
delivery access control check.

For most policies, the inpcb label will simply be a cache of the
socket label, so a new protocol switch method is introduced,
pr_sosetlabel() to notify protocols that the socket layer label
has been updated so that the cache can be updated while holding
appropriate locks.  Most protocols implement this using
pru_sosetlabel_null(), but IPv4/IPv6 protocols using inpcbs use
the the worker function in_pcbsosetlabel(), which calls into the
MAC Framework to perform a cache update.

Biba, LOMAC, and MLS implement these entry points, as do the stub
policy, and test policy.

Reviewed by:	sam, bms
Obtained from:	TrustedBSD Project
Sponsored by:	DARPA, Network Associates Laboratories

2 files changed, 4 insertions, 2 deletions

diff --git a/sys/netatalk/ddp_pcb.c b/sys/netatalk/ddp_pcb.c
index 69b8958..1b91a05 100644
--- a/sys/netatalk/ddp_pcb.c
+++ b/sys/netatalk/ddp_pcb.c
@@ -590,5 +590,6 @@ struct pr_usrreqs ddp_usrreqs = {
 	at_setsockaddr,
 	sosend,
 	soreceive,
-	sopoll
+	sopoll,
+	pru_sosetlabel_null
 };
diff --git a/sys/netatalk/ddp_usrreq.c b/sys/netatalk/ddp_usrreq.c
index 69b8958..1b91a05 100644
--- a/sys/netatalk/ddp_usrreq.c
+++ b/sys/netatalk/ddp_usrreq.c
@@ -590,5 +590,6 @@ struct pr_usrreqs ddp_usrreqs = {
 	at_setsockaddr,
 	sosend,
 	soreceive,
-	sopoll
+	sopoll,
+	pru_sosetlabel_null
 };