netfilter: Pass socket pointer down through okfn().

On the output paths in particular, we have to sometimes deal with two
socket contexts.  First, and usually skb->sk, is the local socket that
generated the frame.

And second, is potentially the socket used to control a tunneling
socket, such as one the encapsulates using UDP.

We do not want to disassociate skb->sk when encapsulating in order
to fix this, because that would break socket memory accounting.

The most extreme case where this can cause huge problems is an
AF_PACKET socket transmitting over a vxlan device.  We hit code
paths doing checks that assume they are dealing with an ipv4
socket, but are actually operating upon the AF_PACKET one.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 26 insertions, 19 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 26f6f7956168..5da4d15262fd 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -91,14 +91,19 @@ void ip_send_check(struct iphdr *iph)
 }
 EXPORT_SYMBOL(ip_send_check);
 
-int __ip_local_out(struct sk_buff *skb)
+int __ip_local_out_sk(struct sock *sk, struct sk_buff *skb)
 {
 	struct iphdr *iph = ip_hdr(skb);
 
 	iph->tot_len = htons(skb->len);
 	ip_send_check(iph);
-	return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL,
-		       skb_dst(skb)->dev, dst_output);
+	return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, sk, skb, NULL,
+		       skb_dst(skb)->dev, dst_output_sk);
+}
+
+int __ip_local_out(struct sk_buff *skb)
+{
+	return __ip_local_out_sk(skb->sk, skb);
 }
 
 int ip_local_out_sk(struct sock *sk, struct sk_buff *skb)
@@ -163,7 +168,7 @@ int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
 }
 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
 
-static inline int ip_finish_output2(struct sk_buff *skb)
+static inline int ip_finish_output2(struct sock *sk, struct sk_buff *skb)
 {
 	struct dst_entry *dst = skb_dst(skb);
 	struct rtable *rt = (struct rtable *)dst;
@@ -211,7 +216,7 @@ static inline int ip_finish_output2(struct sk_buff *skb)
 	return -EINVAL;
 }
 
-static int ip_finish_output_gso(struct sk_buff *skb)
+static int ip_finish_output_gso(struct sock *sk, struct sk_buff *skb)
 {
 	netdev_features_t features;
 	struct sk_buff *segs;
@@ -220,7 +225,7 @@ static int ip_finish_output_gso(struct sk_buff *skb)
 	/* common case: locally created skb or seglen is <= mtu */
 	if (((IPCB(skb)->flags & IPSKB_FORWARDED) == 0) ||
 	      skb_gso_network_seglen(skb) <= ip_skb_dst_mtu(skb))
-		return ip_finish_output2(skb);
+		return ip_finish_output2(sk, skb);
 
 	/* Slowpath -  GSO segment length is exceeding the dst MTU.
 	 *
@@ -243,7 +248,7 @@ static int ip_finish_output_gso(struct sk_buff *skb)
 		int err;
 
 		segs->next = NULL;
-		err = ip_fragment(segs, ip_finish_output2);
+		err = ip_fragment(sk, segs, ip_finish_output2);
 
 		if (err && ret == 0)
 			ret = err;
@@ -253,22 +258,22 @@ static int ip_finish_output_gso(struct sk_buff *skb)
 	return ret;
 }
 
-static int ip_finish_output(struct sk_buff *skb)
+static int ip_finish_output(struct sock *sk, struct sk_buff *skb)
 {
 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
 	/* Policy lookup after SNAT yielded a new policy */
 	if (skb_dst(skb)->xfrm) {
 		IPCB(skb)->flags |= IPSKB_REROUTED;
-		return dst_output(skb);
+		return dst_output_sk(sk, skb);
 	}
 #endif
 	if (skb_is_gso(skb))
-		return ip_finish_output_gso(skb);
+		return ip_finish_output_gso(sk, skb);
 
 	if (skb->len > ip_skb_dst_mtu(skb))
-		return ip_fragment(skb, ip_finish_output2);
+		return ip_fragment(sk, skb, ip_finish_output2);
 
-	return ip_finish_output2(skb);
+	return ip_finish_output2(sk, skb);
 }
 
 int ip_mc_output(struct sock *sk, struct sk_buff *skb)
@@ -307,7 +312,7 @@ int ip_mc_output(struct sock *sk, struct sk_buff *skb)
 			struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 			if (newskb)
 				NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
-					newskb, NULL, newskb->dev,
+					sk, newskb, NULL, newskb->dev,
 					dev_loopback_xmit);
 		}
 
@@ -322,11 +327,11 @@ int ip_mc_output(struct sock *sk, struct sk_buff *skb)
 	if (rt->rt_flags&RTCF_BROADCAST) {
 		struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 		if (newskb)
-			NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb,
+			NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, sk, newskb,
 				NULL, newskb->dev, dev_loopback_xmit);
 	}
 
-	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL,
+	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, sk, skb, NULL,
 			    skb->dev, ip_finish_output,
 			    !(IPCB(skb)->flags & IPSKB_REROUTED));
 }
@@ -340,7 +345,8 @@ int ip_output(struct sock *sk, struct sk_buff *skb)
 	skb->dev = dev;
 	skb->protocol = htons(ETH_P_IP);
 
-	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev,
+	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, sk, skb,
+			    NULL, dev,
 			    ip_finish_output,
 			    !(IPCB(skb)->flags & IPSKB_REROUTED));
 }
@@ -480,7 +486,8 @@ static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
  *	single device frame, and queue such a frame for sending.
  */
 
-int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
+int ip_fragment(struct sock *sk, struct sk_buff *skb,
+		int (*output)(struct sock *, struct sk_buff *))
 {
 	struct iphdr *iph;
 	int ptr;
@@ -593,7 +600,7 @@ int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
 				ip_send_check(iph);
 			}
 
-			err = output(skb);
+			err = output(sk, skb);
 
 			if (!err)
 				IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
@@ -730,7 +737,7 @@ slow_path:
 
 		ip_send_check(iph);
 
-		err = output(skb2);
+		err = output(sk, skb2);
 		if (err)
 			goto fail;