ipv6/gro: insert temporary HBH/jumbo header

Following patch will add GRO_IPV6_MAX_SIZE, allowing gro to build
BIG TCP ipv6 packets (bigger than 64K).

This patch changes ipv6_gro_complete() to insert a HBH/jumbo header
so that resulting packet can go through IPv6/TCP stacks.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Alexander Duyck <alexanderduyck@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
index a6a6c15..d12dba2 100644 (file)
--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -342,15 +342,43 @@ static struct sk_buff *ip4ip6_gro_receive(struct list_head *head,
 INDIRECT_CALLABLE_SCOPE int ipv6_gro_complete(struct sk_buff *skb, int nhoff)
 {
        const struct net_offload *ops;
-       struct ipv6hdr *iph = (struct ipv6hdr *)(skb->data + nhoff);
+       struct ipv6hdr *iph;
        int err = -ENOSYS;
+       u32 payload_len;
 
        if (skb->encapsulation) {
                skb_set_inner_protocol(skb, cpu_to_be16(ETH_P_IPV6));
                skb_set_inner_network_header(skb, nhoff);
        }
 
-       iph->payload_len = htons(skb->len - nhoff - sizeof(*iph));
+       payload_len = skb->len - nhoff - sizeof(*iph);
+       if (unlikely(payload_len > IPV6_MAXPLEN)) {
+               struct hop_jumbo_hdr *hop_jumbo;
+               int hoplen = sizeof(*hop_jumbo);
+
+               /* Move network header left */
+               memmove(skb_mac_header(skb) - hoplen, skb_mac_header(skb),
+                       skb->transport_header - skb->mac_header);
+               skb->data -= hoplen;
+               skb->len += hoplen;
+               skb->mac_header -= hoplen;
+               skb->network_header -= hoplen;
+               iph = (struct ipv6hdr *)(skb->data + nhoff);
+               hop_jumbo = (struct hop_jumbo_hdr *)(iph + 1);
+
+               /* Build hop-by-hop options */
+               hop_jumbo->nexthdr = iph->nexthdr;
+               hop_jumbo->hdrlen = 0;
+               hop_jumbo->tlv_type = IPV6_TLV_JUMBO;
+               hop_jumbo->tlv_len = 4;
+               hop_jumbo->jumbo_payload_len = htonl(payload_len + hoplen);
+
+               iph->nexthdr = NEXTHDR_HOP;
+               iph->payload_len = 0;
+       } else {
+               iph = (struct ipv6hdr *)(skb->data + nhoff);
+               iph->payload_len = htons(payload_len);
+       }
 
        nhoff += sizeof(*iph) + ipv6_exthdrs_len(iph, &ops);
        if (WARN_ON(!ops || !ops->callbacks.gro_complete))