gso: validate gso_type on ipip style tunnels

Commit 121d57a ("gso: validate gso_type in GSO handlers") added
gso_type validation to existing gso_segment callback functions, to
filter out illegal and potentially dangerous SKB_GSO_DODGY packets.

Convert tunnels that now call inet_gso_segment and ipv6_gso_segment
directly to have their own callbacks and extend validation to these.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/af_inet.c

@@ -1385,6 +1385,15 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
 }
 EXPORT_SYMBOL(inet_gso_segment);
 
+static struct sk_buff *ipip_gso_segment(struct sk_buff *skb,
+					netdev_features_t features)
+{
+	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_IPXIP4))
+		return ERR_PTR(-EINVAL);
+
+	return inet_gso_segment(skb, features);
+}
+
 INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp4_gro_receive(struct list_head *,
 							   struct sk_buff *));
 INDIRECT_CALLABLE_DECLARE(struct sk_buff *udp4_gro_receive(struct list_head *,
@@ -1861,7 +1870,7 @@ static struct packet_offload ip_packet_offload __read_mostly = {
 
 static const struct net_offload ipip_offload = {
 	.callbacks = {
-		.gso_segment	= inet_gso_segment,
+		.gso_segment	= ipip_gso_segment,
 		.gro_receive	= ipip_gro_receive,
 		.gro_complete	= ipip_gro_complete,
 	},

net/ipv6/ip6_offload.c

@@ -383,25 +383,52 @@ static struct packet_offload ipv6_packet_offload __read_mostly = {
 	},
 };
 
+static struct sk_buff *sit_gso_segment(struct sk_buff *skb,
+				       netdev_features_t features)
+{
+	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_IPXIP4))
+		return ERR_PTR(-EINVAL);
+
+	return ipv6_gso_segment(skb, features);
+}
+
+static struct sk_buff *ip4ip6_gso_segment(struct sk_buff *skb,
+					  netdev_features_t features)
+{
+	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_IPXIP6))
+		return ERR_PTR(-EINVAL);
+
+	return inet_gso_segment(skb, features);
+}
+
+static struct sk_buff *ip6ip6_gso_segment(struct sk_buff *skb,
+					  netdev_features_t features)
+{
+	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_IPXIP6))
+		return ERR_PTR(-EINVAL);
+
+	return ipv6_gso_segment(skb, features);
+}
+
 static const struct net_offload sit_offload = {
 	.callbacks = {
-		.gso_segment	= ipv6_gso_segment,
+		.gso_segment	= sit_gso_segment,
 		.gro_receive    = sit_ip6ip6_gro_receive,
 		.gro_complete   = sit_gro_complete,
 	},
 };
 
 static const struct net_offload ip4ip6_offload = {
 	.callbacks = {
-		.gso_segment	= inet_gso_segment,
+		.gso_segment	= ip4ip6_gso_segment,
 		.gro_receive    = ip4ip6_gro_receive,
 		.gro_complete   = ip4ip6_gro_complete,
 	},
 };
 
 static const struct net_offload ip6ip6_offload = {
 	.callbacks = {
-		.gso_segment	= ipv6_gso_segment,
+		.gso_segment	= ip6ip6_gso_segment,
 		.gro_receive    = sit_ip6ip6_gro_receive,
 		.gro_complete   = ip6ip6_gro_complete,
 	},