From: Jesse Gross <jesse@kernel.org>
Date: Sat, 19 Mar 2016 16:32:01 +0000 (-0700)
Subject: tunnels: Don't apply GRO to multiple layers of encapsulation.
X-Git-Tag: v4.1.12-92~28^2~4
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=b9536a9dec7e739919a8ec4ed7fec3123762dbe2;p=users%2Fjedix%2Flinux-maple.git

tunnels: Don't apply GRO to multiple layers of encapsulation.

Orabug: 24842686
CVE: CVE-2016-8666

When drivers express support for TSO of encapsulated packets, they
only mean that they can do it for one layer of encapsulation.
Supporting additional levels would mean updating, at a minimum,
more IP length fields and they are unaware of this.

No encapsulation device expresses support for handling offloaded
encapsulated packets, so we won't generate these types of frames
in the transmit path. However, GRO doesn't have a check for
multiple levels of encapsulation and will attempt to build them.

UDP tunnel GRO actually does prevent this situation but it only
handles multiple UDP tunnels stacked on top of each other. This
generalizes that solution to prevent any kind of tunnel stacking
that would cause problems.

Fixes: bf5a755f ("net-gre-gro: Add GRE support to the GRO stack")
Signed-off-by: Jesse Gross <jesse@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit fac8e0f579695a3ecbc4d3cac369139d7f819971)
Signed-off-by: Brian Maly <brian.maly@oracle.com>

Conflicts:
	net/ipv4/af_inet.c
	net/ipv6/ip6_offload.c
---

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 05b9a694e2131..c5f7d5ff17c79 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1939,8 +1939,8 @@ struct napi_gro_cb {
 	/* This is non-zero if the packet may be of the same flow. */
 	u8	same_flow:1;
 
-	/* Used in udp_gro_receive */
-	u8	udp_mark:1;
+	/* Used in tunnel GRO receive */
+	u8	encap_mark:1;
 
 	/* GRO checksum is valid */
 	u8	csum_valid:1;
diff --git a/net/core/dev.c b/net/core/dev.c
index aa82f9ab6a36d..9ec0d9cd7f55c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4057,7 +4057,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
 		NAPI_GRO_CB(skb)->same_flow = 0;
 		NAPI_GRO_CB(skb)->flush = 0;
 		NAPI_GRO_CB(skb)->free = 0;
-		NAPI_GRO_CB(skb)->udp_mark = 0;
+		NAPI_GRO_CB(skb)->encap_mark = 0;
 		NAPI_GRO_CB(skb)->gro_remcsum_start = 0;
 
 		/* Setup for GRO checksum validation */
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 8b47a4d79d040..0ca3d6ccbc603 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1383,6 +1383,19 @@ out:
 	return pp;
 }
 
+static struct sk_buff **ipip_gro_receive(struct sk_buff **head,
+					 struct sk_buff *skb)
+{
+	if (NAPI_GRO_CB(skb)->encap_mark) {
+		NAPI_GRO_CB(skb)->flush = 1;
+		return NULL;
+	}
+
+	NAPI_GRO_CB(skb)->encap_mark = 1;
+
+	return inet_gro_receive(head, skb);
+}
+
 int inet_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
 {
 	if (sk->sk_family == AF_INET)
@@ -1641,7 +1654,7 @@ static struct packet_offload ip_packet_offload __read_mostly = {
 static const struct net_offload ipip_offload = {
 	.callbacks = {
 		.gso_segment	= inet_gso_segment,
-		.gro_receive	= inet_gro_receive,
+		.gro_receive	= ipip_gro_receive,
 		.gro_complete	= inet_gro_complete,
 	},
 };
diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c
index 5aa46d4b44efb..05d81b88222eb 100644
--- a/net/ipv4/gre_offload.c
+++ b/net/ipv4/gre_offload.c
@@ -127,6 +127,11 @@ static struct sk_buff **gre_gro_receive(struct sk_buff **head,
 	struct packet_offload *ptype;
 	__be16 type;
 
+	if (NAPI_GRO_CB(skb)->encap_mark)
+		goto out;
+
+	NAPI_GRO_CB(skb)->encap_mark = 1;
+
 	off = skb_gro_offset(skb);
 	hlen = off + sizeof(*greh);
 	greh = skb_gro_header_fast(skb, off);
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index f9386160cbee0..0e36e56dfd225 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -299,14 +299,14 @@ struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
 	unsigned int off = skb_gro_offset(skb);
 	int flush = 1;
 
-	if (NAPI_GRO_CB(skb)->udp_mark ||
+	if (NAPI_GRO_CB(skb)->encap_mark ||
 	    (skb->ip_summed != CHECKSUM_PARTIAL &&
 	     NAPI_GRO_CB(skb)->csum_cnt == 0 &&
 	     !NAPI_GRO_CB(skb)->csum_valid))
 		goto out;
 
-	/* mark that this skb passed once through the udp gro layer */
-	NAPI_GRO_CB(skb)->udp_mark = 1;
+	/* mark that this skb passed once through the tunnel gro layer */
+	NAPI_GRO_CB(skb)->encap_mark = 1;
 
 	rcu_read_lock();
 	uo_priv = rcu_dereference(udp_offload_base);