Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec

Steffen Klassert says:

====================
This pull request fixes some issues that arise when 6in4 or 4in6 tunnels
are used in combination with IPsec, all from Hannes Frederic Sowa and a
null pointer dereference when queueing packets to the policy hold queue.

1) We might access the local error handler of the wrong address family if
   6in4 or 4in6 tunnel is protected by ipsec. Fix this by addind a pointer
   to the correct local_error to xfrm_state_afinet.

2) Add a helper function to always refer to the correct interpretation
   of skb->sk.

3) Call skb_reset_inner_headers to record the position of the inner headers
   when adding a new one in various ipv6 tunnels. This is needed to identify
   the addresses where to send back errors in the xfrm layer.

4) Dereference inner ipv6 header if encapsulated to always call the
   right error handler.

5) Choose protocol family by skb protocol to not call the wrong
   xfrm{4,6}_local_error handler in case an ipv6 sockets is used
   in ipv4 mode.

6) Partly revert "xfrm: introduce helper for safe determination of mtu"
   because this introduced pmtu discovery problems.

7) Set skb->protocol on tcp, raw and ip6_append_data genereated skbs.
   We need this to get the correct mtu informations in xfrm.

8) Fix null pointer dereference in xdst_queue_output.
====================

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

3 files changed, 12 insertions, 13 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 4bcabf3ab4c..9ee17e3d11c 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -211,14 +211,6 @@ static inline int ip_finish_output2(struct sk_buff *skb)
 	return -EINVAL;
 }
 
-static inline int ip_skb_dst_mtu(struct sk_buff *skb)
-{
-	struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL;
-
-	return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ?
-	       skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb));
-}
-
 static int ip_finish_output(struct sk_buff *skb)
 {
 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
diff --git a/net/ipv4/xfrm4_output.c b/net/ipv4/xfrm4_output.c
index 327a617d594..baa0f63731f 100644
--- a/net/ipv4/xfrm4_output.c
+++ b/net/ipv4/xfrm4_output.c
@@ -21,7 +21,6 @@
 static int xfrm4_tunnel_check_size(struct sk_buff *skb)
 {
 	int mtu, ret = 0;
-	struct dst_entry *dst;
 
 	if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
 		goto out;
@@ -29,12 +28,10 @@ static int xfrm4_tunnel_check_size(struct sk_buff *skb)
 	if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df)
 		goto out;
 
-	dst = skb_dst(skb);
-	mtu = dst_mtu(dst);
+	mtu = dst_mtu(skb_dst(skb));
 	if (skb->len > mtu) {
 		if (skb->sk)
-			ip_local_error(skb->sk, EMSGSIZE, ip_hdr(skb)->daddr,
-				       inet_sk(skb->sk)->inet_dport, mtu);
+			xfrm_local_error(skb, mtu);
 		else
 			icmp_send(skb, ICMP_DEST_UNREACH,
 				  ICMP_FRAG_NEEDED, htonl(mtu));
@@ -99,3 +96,12 @@ int xfrm4_output(struct sk_buff *skb)
 			    x->outer_mode->afinfo->output_finish,
 			    !(IPCB(skb)->flags & IPSKB_REROUTED));
 }
+
+void xfrm4_local_error(struct sk_buff *skb, u32 mtu)
+{
+	struct iphdr *hdr;
+
+	hdr = skb->encapsulation ? inner_ip_hdr(skb) : ip_hdr(skb);
+	ip_local_error(skb->sk, EMSGSIZE, hdr->daddr,
+		       inet_sk(skb->sk)->inet_dport, mtu);
+}
diff --git a/net/ipv4/xfrm4_state.c b/net/ipv4/xfrm4_state.c
index 9258e751bab..0b2a0641526 100644
--- a/net/ipv4/xfrm4_state.c
+++ b/net/ipv4/xfrm4_state.c
@@ -83,6 +83,7 @@ static struct xfrm_state_afinfo xfrm4_state_afinfo = {
 	.extract_input		= xfrm4_extract_input,
 	.extract_output		= xfrm4_extract_output,
 	.transport_finish	= xfrm4_transport_finish,
+	.local_error		= xfrm4_local_error,
 };
 
 void __init xfrm4_state_init(void)