ipvs: allow transmit of GRO aggregated skbs

Attempt at allowing LVS to transmit skbs of greater than MTU length that
have been aggregated by GRO and can thus be deaggregated by GSO.

Cc: Julian Anastasov <ja@ssi.bg>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NSimon Horman <horms@verge.net.au>

net/netfilter/ipvs/ip_vs_xmit.c

@@ -407,7 +407,8 @@ ip_vs_bypass_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 
 	/* MTU checking */
 	mtu = dst_mtu(&rt->dst);
-	if ((skb->len > mtu) && (iph->frag_off & htons(IP_DF))) {
+	if ((skb->len > mtu) && (iph->frag_off & htons(IP_DF)) &&
+	    !skb_is_gso(skb)) {
 		ip_rt_put(rt);
 		icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));
 		IP_VS_DBG_RL("%s(): frag needed\n", __func__);
@@ -460,7 +461,7 @@ ip_vs_bypass_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 
 	/* MTU checking */
 	mtu = dst_mtu(&rt->dst);
-	if (skb->len > mtu) {
+	if (skb->len > mtu && !skb_is_gso(skb)) {
 		if (!skb->dev) {
 			struct net *net = dev_net(skb_dst(skb)->dev);
 
@@ -560,7 +561,8 @@ ip_vs_nat_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 
 	/* MTU checking */
 	mtu = dst_mtu(&rt->dst);
-	if ((skb->len > mtu) && (iph->frag_off & htons(IP_DF))) {
+	if ((skb->len > mtu) && (iph->frag_off & htons(IP_DF)) &&
+	    !skb_is_gso(skb)) {
 		icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));
 		IP_VS_DBG_RL_PKT(0, AF_INET, pp, skb, 0,
 				 "ip_vs_nat_xmit(): frag needed for");
@@ -675,7 +677,7 @@ ip_vs_nat_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 
 	/* MTU checking */
 	mtu = dst_mtu(&rt->dst);
-	if (skb->len > mtu) {
+	if (skb->len > mtu && !skb_is_gso(skb)) {
 		if (!skb->dev) {
 			struct net *net = dev_net(skb_dst(skb)->dev);
 
@@ -790,8 +792,8 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 
 	df |= (old_iph->frag_off & htons(IP_DF));
 
-	if ((old_iph->frag_off & htons(IP_DF))
-	    && mtu < ntohs(old_iph->tot_len)) {
+	if ((old_iph->frag_off & htons(IP_DF) &&
+	    mtu < ntohs(old_iph->tot_len) && !skb_is_gso(skb))) {
 		icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));
 		IP_VS_DBG_RL("%s(): frag needed\n", __func__);
 		goto tx_error_put;
@@ -903,7 +905,8 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 	if (skb_dst(skb))
 		skb_dst(skb)->ops->update_pmtu(skb_dst(skb), mtu);
 
-	if (mtu < ntohs(old_iph->payload_len) + sizeof(struct ipv6hdr)) {
+	if (mtu < ntohs(old_iph->payload_len) + sizeof(struct ipv6hdr) &&
+	    !skb_is_gso(skb)) {
 		if (!skb->dev) {
 			struct net *net = dev_net(skb_dst(skb)->dev);
 
@@ -1008,7 +1011,8 @@ ip_vs_dr_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 
 	/* MTU checking */
 	mtu = dst_mtu(&rt->dst);
-	if ((iph->frag_off & htons(IP_DF)) && skb->len > mtu) {
+	if ((iph->frag_off & htons(IP_DF)) && skb->len > mtu &&
+	    !skb_is_gso(skb)) {
 		icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));
 		ip_rt_put(rt);
 		IP_VS_DBG_RL("%s(): frag needed\n", __func__);
@@ -1175,7 +1179,8 @@ ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 
 	/* MTU checking */
 	mtu = dst_mtu(&rt->dst);
-	if ((skb->len > mtu) && (ip_hdr(skb)->frag_off & htons(IP_DF))) {
+	if ((skb->len > mtu) && (ip_hdr(skb)->frag_off & htons(IP_DF)) &&
+	    !skb_is_gso(skb)) {
 		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
 		IP_VS_DBG_RL("%s(): frag needed\n", __func__);
 		goto tx_error_put;
@@ -1289,7 +1294,7 @@ ip_vs_icmp_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 
 	/* MTU checking */
 	mtu = dst_mtu(&rt->dst);
-	if (skb->len > mtu) {
+	if (skb->len > mtu && !skb_is_gso(skb)) {
 		if (!skb->dev) {
 			struct net *net = dev_net(skb_dst(skb)->dev);