Commit 7a682575 authored Sep 23, 2016 by KOVACS Krisztian Committed by Pablo Neira Ayuso Sep 25, 2016

netfilter: xt_socket: fix transparent match for IPv6 request sockets



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.

Based on the suggestion from Eric Dumazet, this change moves the code
initializing no_srccheck to tcp_conn_request(), rendering the above
scenario working again.

Fixes: a9407000 ("netfilter: xt_socket: prepare for TCP_NEW_SYN_RECV support")
Signed-off-by: Alex Badics <alex.badics@balabit.com>
Signed-off-by: KOVACS Krisztian <hidden@balabit.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

parent 58e207e4

net/ipv4/tcp_input.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -6269,6 +6269,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,

		tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
		tcp_openreq_init(req, &tmp_opt, skb, sk);
		inet_rsk(req)->no_srccheck = inet_sk(sk)->transparent;

		/* Note: tcp_v6_init_req() might override ir_iif for link locals */
		inet_rsk(req)->ir_iif = inet_request_bound_dev_if(sk, skb);

net/ipv4/tcp_ipv4.c

+0 −1

Original line number	Diff line number	Diff line
		@@ -1196,7 +1196,6 @@ static void tcp_v4_init_req(struct request_sock *req,

		sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr);
		sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr);
		ireq->no_srccheck = inet_sk(sk_listener)->transparent;
		ireq->opt = tcp_v4_save_options(skb);
		}