xfrm: Fix crash with ipv6 IPsec tunnel and NAT.
The ipv6 xfrm output path is not aware that packets can be
rerouted by NAT to not use IPsec. We crash in this case
because we expect to have a xfrm state at the dst_entry.
This crash happens if the ipv6 layer does IPsec and NAT
or if we have an interfamily IPsec tunnel with ipv4 NAT.
We fix this by checking for a NAT rerouted packet in each
address family and dst_output() to the new destination
in this case.
Reported-by: Martin Pelikan <martin.pelikan@gmail.com>
Tested-by: Martin Pelikan <martin.pelikan@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
diff --git a/net/ipv6/xfrm6_output.c b/net/ipv6/xfrm6_output.c
index 6cd625e..ba62433 100644
--- a/net/ipv6/xfrm6_output.c
+++ b/net/ipv6/xfrm6_output.c
@@ -114,12 +114,6 @@
if (err)
return err;
- memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
-#ifdef CONFIG_NETFILTER
- IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
-#endif
-
- skb->protocol = htons(ETH_P_IPV6);
skb->local_df = 1;
return x->outer_mode->output2(x, skb);
@@ -128,11 +122,13 @@
int xfrm6_output_finish(struct sk_buff *skb)
{
+ memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
+ skb->protocol = htons(ETH_P_IPV6);
+
#ifdef CONFIG_NETFILTER
IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
#endif
- skb->protocol = htons(ETH_P_IPV6);
return xfrm_output(skb);
}
@@ -142,6 +138,13 @@
struct xfrm_state *x = dst->xfrm;
int mtu;
+#ifdef CONFIG_NETFILTER
+ if (!x) {
+ IP6CB(skb)->flags |= IP6SKB_REROUTED;
+ return dst_output(skb);
+ }
+#endif
+
if (skb->protocol == htons(ETH_P_IPV6))
mtu = ip6_skb_dst_mtu(skb);
else
@@ -165,6 +168,7 @@
int xfrm6_output(struct sk_buff *skb)
{
- return NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING, skb, NULL,
- skb_dst(skb)->dev, __xfrm6_output);
+ return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING, skb,
+ NULL, skb_dst(skb)->dev, __xfrm6_output,
+ !(IP6CB(skb)->flags & IP6SKB_REROUTED));
}