The introduction of TCP_NEW_SYN_RECV state, and the addition of request
sockets to the ehash table seems to have broken the --transparent option
of the socket match for IPv6 (around commit a9407000).

Now that the socket lookup finds the TCP_NEW_SYN_RECV socket instead of the
listener, the --transparent option tries to match on the no_srccheck flag
of the request socket.

Unfortunately, that flag was only set for IPv4 sockets in tcp_v4_init_req()
by copying the transparent flag of the listener socket. This effectively
causes '-m socket --transparent' not match on the ACK packet sent by the
client in a TCP handshake.

This change adds the same code initializing no_srccheck to
tcp_v6_init_req(), rendering the above scenario working again.

Signed-off-by: Alex Badics <>
Signed-off-by: KOVACS Krisztian <>
 net/ipv6/tcp_ipv6.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 94f4f89..21f2e5c 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -690,6 +690,7 @@ static void tcp_v6_init_req(struct request_sock *req,
        ireq->ir_v6_rmt_addr = ipv6_hdr(skb)->saddr;
        ireq->ir_v6_loc_addr = ipv6_hdr(skb)->daddr;
+       ireq->no_srccheck = inet_sk(sk_listener)->transparent;
        /* So that link locals have meaning */
        if (!sk_listener->sk_bound_dev_if &&

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