net: Discard and warn about LRO'd skbs received for forwarding

Add skb_warn_if_lro() to test whether an skb was received with LRO and warn if so. Change br_forward(), ip_forward() and ip6_forward() to call it) and discard the skb if it returns true. Signed-off-by: Ben Hutchings <bhutchings@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>

net: Discard and warn about LRO'd skbs received for forwarding
Add skb_warn_if_lro() to test whether an skb was received with LRO and warn if so. Change br_forward(), ip_forward() and ip6_forward() to call it) and discard the skb if it returns true. Signed-off-by: Ben Hutchings <bhutchings@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Ben Hutchings · David S. Miller
1 parent 0187bdfb05
Showing 5 changed files with 29 additions and 1 deletions Side-by-side Diff
include/linux/skbuff.h
net/bridge/br_forward.c
net/core/skbuff.c
net/ipv4/ip_forward.c
net/ipv6/ip6_output.c
@@ -1702,6 +1702,20 @@
 	return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
 }
  
+extern void __skb_warn_lro_forwarding(const struct sk_buff *skb);
+
+static inline bool skb_warn_if_lro(const struct sk_buff *skb)
+{
+	/* LRO sets gso_size but not gso_type, whereas if GSO is really
+	 * wanted then gso_type will be set. */
+	struct skb_shared_info *shinfo = skb_shinfo(skb);
+	if (shinfo->gso_size != 0 && unlikely(shinfo->gso_type == 0)) {
+		__skb_warn_lro_forwarding(skb);
+		return true;
+	}
+	return false;
+}
+
 static inline void skb_forward_csum(struct sk_buff *skb)
 {
 	/* Unfortunately we don't support this one.  Any brave souls? */
@@ -89,7 +89,7 @@
 /* called with rcu_read_lock */
 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
 {
-	if (should_deliver(to, skb)) {
+	if (!skb_warn_if_lro(skb) && should_deliver(to, skb)) {
 		__br_forward(to, skb);
 		return;
 	}
@@ -2583,6 +2583,13 @@
 	return true;
 }
  
+void __skb_warn_lro_forwarding(const struct sk_buff *skb)
+{
+	if (net_ratelimit())
+		pr_warning("%s: received packets cannot be forwarded"
+			   " while LRO is enabled\n", skb->dev->name);
+}
+
 EXPORT_SYMBOL(___pskb_trim);
 EXPORT_SYMBOL(__kfree_skb);
 EXPORT_SYMBOL(kfree_skb);
@@ -2616,6 +2623,7 @@
 EXPORT_SYMBOL(skb_abort_seq_read);
 EXPORT_SYMBOL(skb_find_text);
 EXPORT_SYMBOL(skb_append_datato_frags);
+EXPORT_SYMBOL(__skb_warn_lro_forwarding);
  
 EXPORT_SYMBOL_GPL(skb_to_sgvec);
 EXPORT_SYMBOL_GPL(skb_cow_data);
@@ -56,6 +56,9 @@
 	struct rtable *rt;	/* Route we use */
 	struct ip_options * opt	= &(IPCB(skb)->opt);
  
+	if (skb_warn_if_lro(skb))
+		goto drop;
+
 	if (!xfrm4_policy_check(NULL, XFRM_POLICY_FWD, skb))
 		goto drop;
  
@@ -407,6 +407,9 @@
 	if (ipv6_devconf.forwarding == 0)
 		goto error;
  
+	if (skb_warn_if_lro(skb))
+		goto drop;
+
 	if (!xfrm6_policy_check(NULL, XFRM_POLICY_FWD, skb)) {
 		IP6_INC_STATS(ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS);
 		goto drop;
...	...	@@ -1702,6 +1702,20 @@
1702	1702	return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
1703	1703	}
1704	1704
	1705	+extern void __skb_warn_lro_forwarding(const struct sk_buff *skb);
	1706	+
	1707	+static inline bool skb_warn_if_lro(const struct sk_buff *skb)
	1708	+{
	1709	+ /* LRO sets gso_size but not gso_type, whereas if GSO is really
	1710	+ * wanted then gso_type will be set. */
	1711	+ struct skb_shared_info *shinfo = skb_shinfo(skb);
	1712	+ if (shinfo->gso_size != 0 && unlikely(shinfo->gso_type == 0)) {
	1713	+ __skb_warn_lro_forwarding(skb);
	1714	+ return true;
	1715	+ }
	1716	+ return false;
	1717	+}
	1718	+
1705	1719	static inline void skb_forward_csum(struct sk_buff *skb)
1706	1720	{
1707	1721	/* Unfortunately we don't support this one. Any brave souls? */
...	...	@@ -89,7 +89,7 @@
89	89	/* called with rcu_read_lock */
90	90	void br_forward(const struct net_bridge_port to, struct sk_buff skb)
91	91	{
92		- if (should_deliver(to, skb)) {
	92	+ if (!skb_warn_if_lro(skb) && should_deliver(to, skb)) {
93	93	__br_forward(to, skb);
94	94	return;
95	95	}
...	...	@@ -2583,6 +2583,13 @@
2583	2583	return true;
2584	2584	}
2585	2585
	2586	+void __skb_warn_lro_forwarding(const struct sk_buff *skb)
	2587	+{
	2588	+ if (net_ratelimit())
	2589	+ pr_warning("%s: received packets cannot be forwarded"
	2590	+ " while LRO is enabled\n", skb->dev->name);
	2591	+}
	2592	+
2586	2593	EXPORT_SYMBOL(___pskb_trim);
2587	2594	EXPORT_SYMBOL(__kfree_skb);
2588	2595	EXPORT_SYMBOL(kfree_skb);
...	...	@@ -2616,6 +2623,7 @@
2616	2623	EXPORT_SYMBOL(skb_abort_seq_read);
2617	2624	EXPORT_SYMBOL(skb_find_text);
2618	2625	EXPORT_SYMBOL(skb_append_datato_frags);
	2626	+EXPORT_SYMBOL(__skb_warn_lro_forwarding);
2619	2627
2620	2628	EXPORT_SYMBOL_GPL(skb_to_sgvec);
2621	2629	EXPORT_SYMBOL_GPL(skb_cow_data);
...	...	@@ -56,6 +56,9 @@
56	56	struct rtable rt; / Route we use */
57	57	struct ip_options * opt = &(IPCB(skb)->opt);
58	58
	59	+ if (skb_warn_if_lro(skb))
	60	+ goto drop;
	61	+
59	62	if (!xfrm4_policy_check(NULL, XFRM_POLICY_FWD, skb))
60	63	goto drop;
61	64
...	...	@@ -407,6 +407,9 @@
407	407	if (ipv6_devconf.forwarding == 0)
408	408	goto error;
409	409
	410	+ if (skb_warn_if_lro(skb))
	411	+ goto drop;
	412	+
410	413	if (!xfrm6_policy_check(NULL, XFRM_POLICY_FWD, skb)) {
411	414	IP6_INC_STATS(ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS);
412	415	goto drop;