Do invoke mac_ifnet_check_transmit() and mac_ifnet_create_mbuf() in the loopback and synthetic loopback code so that packets are access control checked and relabeled.  Previously, the MAC Framework enforced that packets sent over the loopback weren't relabeled, but this will allow policies to make explicit choices about how and whether to relabel packets on the loopback.  Also, for SIMPLEX devices, this produces more consistent behavior for looped back packets to the local MAC address by labeling those packets as coming from the interface.
Do invoke mac_ifnet_check_transmit() and mac_ifnet_create_mbuf()
in the loopback and synthetic loopback code so that packets are
access control checked and relabeled.  Previously, the MAC
Framework enforced that packets sent over the loopback weren't
relabeled, but this will allow policies to make explicit choices
about how and whether to relabel packets on the loopback.  Also,
for SIMPLEX devices, this produces more consistent behavior for
looped back packets to the local MAC address by labeling those
packets as coming from the interface.

Discussed with:	csjp
Obtained from:	TrustedBSD Project

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase