[XFRM]: Fix SNAT-related crash in xfrm4_output_finish
When a packet matching an IPsec policy is SNATed so it doesn't match any
policy anymore it looses its xfrm bundle, which makes xfrm4_output_finish
crash because of a NULL pointer dereference.
This patch directs these packets to the original output path instead. Since
the packets have already passed the POST_ROUTING hook, but need to start at
the beginning of the original output path which includes another
POST_ROUTING invocation, a flag is added to the IPCB to indicate that the
packet was rerouted and doesn't need to pass the POST_ROUTING hook again.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/xfrm4_output.c b/net/ipv4/xfrm4_output.c
index d4df0dd..32ad229 100644
--- a/net/ipv4/xfrm4_output.c
+++ b/net/ipv4/xfrm4_output.c
@@ -152,10 +152,16 @@
goto out_exit;
}
-int xfrm4_output_finish(struct sk_buff *skb)
+static int xfrm4_output_finish(struct sk_buff *skb)
{
int err;
+#ifdef CONFIG_NETFILTER
+ if (!skb->dst->xfrm) {
+ IPCB(skb)->flags |= IPSKB_REROUTED;
+ return dst_output(skb);
+ }
+#endif
while (likely((err = xfrm4_output_one(skb)) == 0)) {
nf_reset(skb);
@@ -178,6 +184,7 @@
int xfrm4_output(struct sk_buff *skb)
{
- return NF_HOOK(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dst->dev,
- xfrm4_output_finish);
+ return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dst->dev,
+ xfrm4_output_finish,
+ !(IPCB(skb)->flags & IPSKB_REROUTED));
}