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

1 files changed, 13 insertions, 0 deletions

diff --git a/sys/security/mac_ifoff/mac_ifoff.c b/sys/security/mac_ifoff/mac_ifoff.c
index 19bbc79..c3337d4 100644
--- a/sys/security/mac_ifoff/mac_ifoff.c
+++ b/sys/security/mac_ifoff/mac_ifoff.c
@@ -143,6 +143,18 @@ mac_ifoff_check_ifnet_transmit(struct ifnet *ifnet, struct label *ifnetlabel,
 }
 
 static int
+mac_ifoff_check_inpcb_deliver(struct inpcb *inp, struct label *inplabel,
+    struct mbuf *m, struct label *mlabel)
+{
+
+	M_ASSERTPKTHDR(m);
+	if (m->m_pkthdr.rcvif != NULL)
+		return (check_ifnet_incoming(m->m_pkthdr.rcvif, 0));
+
+	return (0);
+}
+
+static int
 mac_ifoff_check_socket_deliver(struct socket *so, struct label *socketlabel,
     struct mbuf *m, struct label *mbuflabel)
 {
@@ -158,6 +170,7 @@ static struct mac_policy_ops mac_ifoff_ops =
 {
 	.mpo_check_bpfdesc_receive = mac_ifoff_check_bpfdesc_receive,
 	.mpo_check_ifnet_transmit = mac_ifoff_check_ifnet_transmit,
+	.mpo_check_inpcb_deliver = mac_ifoff_check_inpcb_deliver,
 	.mpo_check_socket_deliver = mac_ifoff_check_socket_deliver,
 };