Re: [PATCH net-next 05/15] ipv6/gso: remove temporary HBH/jumbo header

On Thu, Feb 3, 2022 at 5:48 PM Eric Dumazet [off-list ref] wrote:

Well, this does not work at all.

quoted

 static inline bool ipv6_accept_ra(struct inet6_dev *idev)
 {
        /* If forwarding is enabled, RA are not accepted unless the special

diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
index d37a79a8554e92a1dcaa6fd023cafe2114841ece..7f65097c8f30fa19a8c9c265eb4f027e91848021

100644

--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c

@@ -87,6 +87,27 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
        bool gso_partial;

        skb_reset_network_header(skb);
+       if (ipv6_has_hopopt_jumbo(skb)) {
+               const int hophdr_len = sizeof(struct hop_jumbo_hdr);
+               int err;
+
+               err = skb_cow_head(skb, 0);
+               if (err < 0)
+                       return ERR_PTR(err);
+
+               /* remove the HBH header.
+                * Layout: [Ethernet header][IPv6 header][HBH][TCP header]
+                */
+               memmove(skb->data + hophdr_len,
+                       skb->data,

Oh, I must use skb_mac_header() instead of skb->data, sorry for the noise.

quoted

+                       ETH_HLEN + sizeof(struct ipv6hdr));
+               skb->data += hophdr_len;
+               skb->len -= hophdr_len;
+               skb->network_header += hophdr_len;
+               skb->mac_header += hophdr_len;
+               ipv6h = (struct ipv6hdr *)skb->data;
+               ipv6h->nexthdr = IPPROTO_TCP;
+       }
        nhoff = skb_network_header(skb) - skb_mac_header(skb);
        if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
                goto out;