Enhance the sk_assign logic to temporarily store the socket
receive destination, to save the route lookup later on. The dst
reference is kept alive by the caller's socket reference.
Suggested-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Signed-off-by: Joe Stringer <joe@xxxxxxxxxxx>
---
v2: Provide cookie to dst_check() for IPv6 case
v1: Initial version
---
net/core/filter.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/net/core/filter.c b/net/core/filter.c
index f7f9b6631f75..0fada7fe9b75 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5876,6 +5876,21 @@ BPF_CALL_3(bpf_sk_assign, struct sk_buff *, skb, struct sock *, sk, u64, flags)
skb_orphan(skb);
skb->sk = sk;
skb->destructor = sock_pfree;
+ if (sk_fullsock(sk)) {
+ struct dst_entry *dst = READ_ONCE(sk->sk_rx_dst);
+ u32 cookie = 0;
+
+#if IS_ENABLED(CONFIG_IPV6)
+ if (sk->sk_family == AF_INET6)
+ cookie = inet6_sk(sk)->rx_dst_cookie;
+#endif
+ if (dst)
+ dst = dst_check(dst, cookie);
+ if (dst) {
+ skb_dst_drop(skb);
+ skb_dst_set_noref(skb, dst);
+ }
+ }
return 0;
}
--
2.20.1
