[PATCH net-next 2/3] net: gro: parse ipv6 ext headers without frag0

Richard Gobert
2023-12-21T18:58:25Z

This commit utilizes a new helper function, ipv6_gro_pull_exthdrs, which
is used in ipv6_gro_receive to pull ipv6 ext headers instead of
ipv6_gso_pull_exthdrs. To use ipv6_gso_pull_exthdr, pskb_pull and
__skb_push must be used, and frag0 must be invalidated. This commit
removes unnecessary code around the call to ipv6_gso_pull_exthdrs and
enables the frag0 fast path in IPv6 packets with ext headers.

Signed-off-by: Richard Gobert <richardbgobert@gmail.com>
---
net/ipv6/ip6_offload.c | 51 +++++++++++++++++++++++++++++++++---------
1 file changed, 41 insertions(+), 10 deletions(-)

diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
index 0e0b5fed0995..a3b8d9127dbb 100644
--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -37,6 +37,40 @@
INDIRECT_CALL_L4(cb, f2, f1, head, skb); \
})

+static int ipv6_gro_pull_exthdrs(struct sk_buff *skb, int off, int proto)
+{
+ const struct net_offload *ops = NULL;
+ struct ipv6_opt_hdr *opth;
+
+ for (;;) {
+ int len;
+
+ ops = rcu_dereference(inet6_offloads[proto]);
+
+ if (unlikely(!ops))
+ break;
+
+ if (!(ops->flags & INET6_PROTO_GSO_EXTHDR))
+ break;
+
+ opth = skb_gro_header(skb, off + 8, off);
+ if (unlikely(!opth))
+ break;
+
+ len = ipv6_optlen(opth);
+
+ opth = skb_gro_header(skb, off + len, off);
+ if (unlikely(!opth))
+ break;
+ proto = opth->nexthdr;
+
+ off += len;
+ }
+
+ skb_gro_pull(skb, off - skb_network_offset(skb));
+ return proto;
+}
+
static int ipv6_gso_pull_exthdrs(struct sk_buff *skb, int proto)
{
const struct net_offload *ops = NULL;
@@ -203,28 +237,25 @@ INDIRECT_CALLABLE_SCOPE struct sk_buff *ipv6_gro_receive(struct list_head *head,
goto out;

skb_set_network_header(skb, off);
- skb_gro_pull(skb, sizeof(*iph));
- skb_set_transport_header(skb, skb_gro_offset(skb));

- flush += ntohs(iph->payload_len) != skb_gro_len(skb);
+ flush += ntohs(iph->payload_len) != skb->len - hlen;

proto = iph->nexthdr;
ops = rcu_dereference(inet6_offloads[proto]);
if (!ops || !ops->callbacks.gro_receive) {
- pskb_pull(skb, skb_gro_offset(skb));
- skb_gro_frag0_invalidate(skb);
- proto = ipv6_gso_pull_exthdrs(skb, proto);
- skb_gro_pull(skb, -skb_transport_offset(skb));
- skb_reset_transport_header(skb);
- __skb_push(skb, skb_gro_offset(skb));
+ proto = ipv6_gro_pull_exthdrs(skb, hlen, proto);

ops = rcu_dereference(inet6_offloads[proto]);
if (!ops || !ops->callbacks.gro_receive)
goto out;

- iph = ipv6_hdr(skb);
+ iph = skb_gro_network_header(skb);
+ } else {
+ skb_gro_pull(skb, sizeof(*iph));
}

+ skb_set_transport_header(skb, skb_gro_offset(skb));
+
NAPI_GRO_CB(skb)->proto = proto;

flush--;
--
2.36.1