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net/ipv4: disable SMC TCP option with SYN Cookies

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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: 60e2a77807 ("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>
This commit is contained in:
Hans Wippel 2018-03-23 11:05:45 +01:00 committed by David S. Miller
parent b9ee96b45f
commit bc58a1baf2
3 changed files with 7 additions and 0 deletions
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2
net/ipv4/syncookies.c
View File

@ -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);

3
net/ipv4/tcp_input.c
View File

@ -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;

2
net/ipv6/syncookies.c
View File

@ -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.