net/ipv4: disable SMC TCP option with SYN Cookies (bc58a1ba) · Commits · 戴 / test

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: ("tcp: TCP experimental option for SMC") Signed-off-by:

Hans Wippel <hwippel@linux.vnet.ibm.com> Signed-off-by:

Ursula Braun <ubraun@linux.vnet.ibm.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

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.

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