[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/ip_gre.c b/net/ipv4/ip_gre.c
index abe2392..9981dcd 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -830,7 +830,8 @@
skb->h.raw = skb->nh.raw;
skb->nh.raw = skb_push(skb, gre_hlen);
memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
- IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE|IPSKB_XFRM_TRANSFORMED);
+ IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
+ IPSKB_REROUTED);
dst_release(skb->dst);
skb->dst = &rt->u.dst;
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 3324fbf..57d290d 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -207,8 +207,10 @@
{
#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
/* Policy lookup after SNAT yielded a new policy */
- if (skb->dst->xfrm != NULL)
- return xfrm4_output_finish(skb);
+ if (skb->dst->xfrm != NULL) {
+ IPCB(skb)->flags |= IPSKB_REROUTED;
+ return dst_output(skb);
+ }
#endif
if (skb->len > dst_mtu(skb->dst) &&
!(skb_shinfo(skb)->ufo_size || skb_shinfo(skb)->tso_size))
@@ -271,8 +273,9 @@
newskb->dev, ip_dev_loopback_xmit);
}
- return NF_HOOK(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dev,
- ip_finish_output);
+ return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dev,
+ ip_finish_output,
+ !(IPCB(skb)->flags & IPSKB_REROUTED));
}
int ip_output(struct sk_buff *skb)
@@ -284,8 +287,9 @@
skb->dev = dev;
skb->protocol = htons(ETH_P_IP);
- return NF_HOOK(PF_INET, NF_IP_POST_ROUTING, skb, NULL, dev,
- ip_finish_output);
+ return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, dev,
+ ip_finish_output,
+ !(IPCB(skb)->flags & IPSKB_REROUTED));
}
int ip_queue_xmit(struct sk_buff *skb, int ipfragok)
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index e5cbe72..03d1374 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -622,7 +622,8 @@
skb->h.raw = skb->nh.raw;
skb->nh.raw = skb_push(skb, sizeof(struct iphdr));
memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
- IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE|IPSKB_XFRM_TRANSFORMED);
+ IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
+ IPSKB_REROUTED);
dst_release(skb->dst);
skb->dst = &rt->u.dst;
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));
}