Introduce a new entry point, mac_create_mbuf_from_firewall. This entry point

exists to allow the mandatory access control policy to properly initialize
mbufs generated by the firewall. An example where this might happen is keep
alive packets, or ICMP error packets in response to other packets.

This takes care of kernel panics associated with un-initialize mbuf labels
when the firewall generates packets.

[1] I modified this patch from it's original version, the initial patch
    introduced a number of entry points which were programmatically
    equivalent. So I introduced only one. Instead, we should leverage
    mac_create_mbuf_netlayer() which is used for similar situations,
    an example being icmp_error()

    This will minimize the impact associated with the MFC

Submitted by:	mlaier [1]
MFC after:	1 week

This is a RELENG_6 candidate

1 files changed, 12 insertions, 0 deletions

diff --git a/sys/security/mac_lomac/mac_lomac.c b/sys/security/mac_lomac/mac_lomac.c
index b68fd25..8ae03e0 100644
--- a/sys/security/mac_lomac/mac_lomac.c
+++ b/sys/security/mac_lomac/mac_lomac.c
@@ -1446,6 +1446,17 @@ mac_lomac_inpcb_sosetlabel(struct socket *so, struct label *solabel,
 	mac_lomac_copy_single(source, dest);
 }
 
+static void
+mac_lomac_create_mbuf_from_firewall(struct mbuf *m, struct label *label)
+{
+	struct mac_lomac *dest;
+
+	dest = SLOT(label);
+
+	/* XXX: where is the label for the firewall really comming from? */
+	mac_lomac_set_single(dest, MAC_LOMAC_TYPE_EQUAL, 0);
+}
+
 /*
  * Labeling event operations: processes.
  */
@@ -2685,6 +2696,7 @@ static struct mac_policy_ops mac_lomac_ops =
 	.mpo_check_vnode_setutimes = mac_lomac_check_vnode_setutimes,
 	.mpo_check_vnode_write = mac_lomac_check_vnode_write,
 	.mpo_thread_userret = mac_lomac_thread_userret,
+	.mpo_create_mbuf_from_firewall = mac_lomac_create_mbuf_from_firewall,
 };
 
 MAC_POLICY_SET(&mac_lomac_ops, mac_lomac, "TrustedBSD MAC/LOMAC",