SELinux: Only store the network interface's ifindex

Instead of storing the packet's network interface name store the ifindex.  This
allows us to defer the need to lookup the net_device structure until the audit
record is generated meaning that in the majority of cases we never need to
bother with this at all.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index be54433..1a1fa3f 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3928,7 +3928,7 @@
 		family = PF_INET;
 
 	AVC_AUDIT_DATA_INIT(&ad, NET);
-	ad.u.net.netif = skb->dev ? skb->dev->name : "[unknown]";
+	ad.u.net.netif = skb->iif;
 	ad.u.net.family = family;
 
 	err = selinux_parse_skb(skb, &ad, &addrp, &len, 1, NULL);
@@ -4259,7 +4259,7 @@
 	sksec = sk->sk_security;
 
 	AVC_AUDIT_DATA_INIT(&ad, NET);
-	ad.u.net.netif = dev->name;
+	ad.u.net.netif = dev->ifindex;
 	ad.u.net.family = family;
 
 	err = selinux_parse_skb(skb, &ad, &addrp, &len, 0, &proto);