[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/include/linux/netfilter.h b/include/linux/netfilter.h
index 4cf6088..3ca3d9e 100644
--- a/include/linux/netfilter.h
+++ b/include/linux/netfilter.h
@@ -184,8 +184,11 @@
struct sk_buff **pskb,
struct net_device *indev,
struct net_device *outdev,
- int (*okfn)(struct sk_buff *), int thresh)
+ int (*okfn)(struct sk_buff *), int thresh,
+ int cond)
{
+ if (!cond)
+ return 1;
#ifndef CONFIG_NETFILTER_DEBUG
if (list_empty(&nf_hooks[pf][hook]))
return 1;
@@ -197,7 +200,7 @@
struct net_device *indev, struct net_device *outdev,
int (*okfn)(struct sk_buff *))
{
- return nf_hook_thresh(pf, hook, pskb, indev, outdev, okfn, INT_MIN);
+ return nf_hook_thresh(pf, hook, pskb, indev, outdev, okfn, INT_MIN, 1);
}
/* Activate hook; either okfn or kfree_skb called, unless a hook
@@ -224,7 +227,13 @@
#define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh) \
({int __ret; \
-if ((__ret=nf_hook_thresh(pf, hook, &(skb), indev, outdev, okfn, thresh)) == 1)\
+if ((__ret=nf_hook_thresh(pf, hook, &(skb), indev, outdev, okfn, thresh, 1)) == 1)\
+ __ret = (okfn)(skb); \
+__ret;})
+
+#define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) \
+({int __ret; \
+if ((__ret=nf_hook_thresh(pf, hook, &(skb), indev, outdev, okfn, INT_MIN, cond)) == 1)\
__ret = (okfn)(skb); \
__ret;})
@@ -295,11 +304,13 @@
#else /* !CONFIG_NETFILTER */
#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
+#define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
static inline int nf_hook_thresh(int pf, unsigned int hook,
struct sk_buff **pskb,
struct net_device *indev,
struct net_device *outdev,
- int (*okfn)(struct sk_buff *), int thresh)
+ int (*okfn)(struct sk_buff *), int thresh,
+ int cond)
{
return okfn(*pskb);
}
diff --git a/include/net/ip.h b/include/net/ip.h
index 8de0697..fab3d5b 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -41,6 +41,7 @@
#define IPSKB_XFRM_TUNNEL_SIZE 2
#define IPSKB_XFRM_TRANSFORMED 4
#define IPSKB_FRAG_COMPLETE 8
+#define IPSKB_REROUTED 16
};
struct ipcm_cookie
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index d09ca0e..d6111a2 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -866,7 +866,6 @@
extern int xfrm_init_state(struct xfrm_state *x);
extern int xfrm4_rcv(struct sk_buff *skb);
extern int xfrm4_output(struct sk_buff *skb);
-extern int xfrm4_output_finish(struct sk_buff *skb);
extern int xfrm4_tunnel_register(struct xfrm_tunnel *handler);
extern int xfrm4_tunnel_deregister(struct xfrm_tunnel *handler);
extern int xfrm6_rcv_spi(struct sk_buff **pskb, u32 spi);
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));
}
