netfilter: nfnetlink_queue: avoid expensive gso segmentation and checksum fixup

Userspace can now indicate that it can cope with larger-than-mtu sized
packets and packets that have invalid ipv4/tcp checksums.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/uapi/linux/netfilter/nfnetlink_queue.h

@@ -97,7 +97,8 @@ enum nfqnl_attr_config {
 /* Flags for NFQA_CFG_FLAGS */
 #define NFQA_CFG_F_FAIL_OPEN			(1 << 0)
 #define NFQA_CFG_F_CONNTRACK			(1 << 1)
-#define NFQA_CFG_F_MAX				(1 << 2)
+#define NFQA_CFG_F_GSO				(1 << 2)
+#define NFQA_CFG_F_MAX				(1 << 3)
 
 /* flags for NFQA_SKB_INFO */
 /* packet appears to have wrong checksums, but they are ok */

net/netfilter/nfnetlink_queue_core.c

@@ -327,7 +327,8 @@ nfqnl_build_packet_message(struct nfqnl_instance *queue,
 		break;
 
 	case NFQNL_COPY_PACKET:
-		if (entskb->ip_summed == CHECKSUM_PARTIAL &&
+		if (!(queue->flags & NFQA_CFG_F_GSO) &&
+		    entskb->ip_summed == CHECKSUM_PARTIAL &&
 		    skb_checksum_help(entskb))
 			return NULL;
 
@@ -636,7 +637,7 @@ nfqnl_enqueue_packet(struct nf_queue_entry *entry, unsigned int queuenum)
 	if (queue->copy_mode == NFQNL_COPY_NONE)
 		return -EINVAL;
 
-	if (!skb_is_gso(entry->skb))
+	if ((queue->flags & NFQA_CFG_F_GSO) || !skb_is_gso(entry->skb))
 		return __nfqnl_enqueue_packet(net, queue, entry);
 
 	skb = entry->skb;