tcp: directly drop skb in cookie check for ipv4

Only move the skb drop from tcp_v4_do_rcv() to cookie_v4_check() itself,
no other changes made. It can help us refine the specific drop reasons
later.

Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index be88bf586ff9ffba2190a1fd60a1ed3ce5f73d06..38f331da6677f5cbb3f9f275ef539a535dfe5d42 100644 (file)
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -408,6 +408,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
        struct rtable *rt;
        __u8 rcv_wscale;
        int full_space;
+       SKB_DR(reason);
 
        if (!READ_ONCE(net->ipv4.sysctl_tcp_syncookies) ||
            !th->ack || th->rst)
@@ -477,10 +478,13 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
         */
        if (ret)
                inet_sk(ret)->cork.fl.u.ip4 = fl4;
+       else
+               goto out_drop;
 out:
        return ret;
 out_free:
        reqsk_free(req);
 out_drop:
+       kfree_skb_reason(skb, reason);
        return NULL;
 }

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 0c50c5a32b84a3b601510655ecaa39b46a8f0b34..0a944e1090886c86c3c0c47eed6110cb35759d80 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1915,7 +1915,7 @@ int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
                struct sock *nsk = tcp_v4_cookie_check(sk, skb);
 
                if (!nsk)
-                       goto discard;
+                       return 0;
                if (nsk != sk) {
                        if (tcp_child_process(sk, nsk, skb)) {
                                rsk = nsk;