[PATCH 2/2] ipvs: Extend MTU check to account for IPv6 NAT defrag changes

[Jesper Dangaard Brouer <brouer@xxxxxxxxxx>]

This patch is necessary, to make IPVS work, after Patrick McHardys
IPv6 NAT defragmentation changes.

Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
---

I would appriciate, if someone (e.g. Julian) double check the tunnel mode code.
--Jesper

 net/netfilter/ipvs/ip_vs_xmit.c |   16 +++++++++++++---
 1 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index e56f0df..20763de 100644
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -88,7 +88,14 @@ __ip_vs_dst_check(struct ip_vs_dest *dest, u32 rtos)
 static inline bool
 __mtu_check_toobig_v6(const struct sk_buff *skb, u32 mtu)
 {
-       if (skb->len > mtu && !skb_is_gso(skb)) {
+       if (IP6CB(skb)->frag_max_size) {
+               /* frag_max_size tell us that, this packet have been
+                * defragmented by netfilter IPv6 conntrack module.
+                */
+               if (IP6CB(skb)->frag_max_size > mtu)
+                       return true; /* largest fragment violate MTU */
+       }
+       else if (skb->len > mtu && !skb_is_gso(skb)) {
                return true; /* Packet size violate MTU size */
        }
        return false;
@@ -956,8 +963,11 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct 
ip_vs_conn *cp,
                skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);
 
        /* MTU checking: Special for tunnel mode */
-       if (mtu < ntohs(old_iph->payload_len) + sizeof(struct ipv6hdr) &&
-           !skb_is_gso(skb)) {
+       if ((!IP6CB(skb)->frag_max_size &&
+            (mtu < ntohs(old_iph->payload_len) + sizeof(struct ipv6hdr) &&
+             !skb_is_gso(skb)))
+           || IP6CB(skb)->frag_max_size + sizeof(struct ipv6hdr) > mtu) {
+
                if (!skb->dev) {
                        struct net *net = dev_net(skb_dst(skb)->dev);
 

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