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Commit bc58a1ba authored by Hans Wippel's avatar Hans Wippel Committed by David S. Miller
Browse files

net/ipv4: disable SMC TCP option with SYN Cookies 



Currently, the SMC experimental TCP option in a SYN packet is lost on
the server side when SYN Cookies are active. However, the corresponding
SYNACK sent back to the client contains the SMC option. This causes an
inconsistent view of the SMC capabilities on the client and server.

This patch disables the SMC option in the SYNACK when SYN Cookies are
active to avoid this issue.

Fixes: 60e2a778 ("tcp: TCP experimental option for SMC")
Signed-off-by: default avatarHans Wippel <hwippel@linux.vnet.ibm.com>
Signed-off-by: default avatarUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b9ee96b4

net/ipv4/syncookies.c

+2 −0
Original line number Diff line number Diff line
@@ -349,6 +349,8 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb) 
	req->ts_recent		= tcp_opt.saw_tstamp ? tcp_opt.rcv_tsval : 0;

	treq->snt_synack	= 0;

	treq->tfo_listener	= false;

	if (IS_ENABLED(CONFIG_SMC))

		ireq->smc_ok = 0;



	ireq->ir_iif = inet_request_bound_dev_if(sk, skb);

net/ipv4/tcp_input.c

+3 −0
Original line number Diff line number Diff line
@@ -6256,6 +6256,9 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops, 
	if (want_cookie && !tmp_opt.saw_tstamp)

		tcp_clear_options(&tmp_opt);



	if (IS_ENABLED(CONFIG_SMC) && want_cookie)

		tmp_opt.smc_ok = 0;



	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;

net/ipv6/syncookies.c

+2 −0
Original line number Diff line number Diff line
@@ -217,6 +217,8 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb) 
	treq->snt_isn = cookie;

	treq->ts_off = 0;

	treq->txhash = net_tx_rndhash();

	if (IS_ENABLED(CONFIG_SMC))

		ireq->smc_ok = 0;



	/*

	 * We need to lookup the dst_entry to get the correct window size.