linux-kernel - [PATCH 5.10 320/593] mptcp: generate subflow hmac after mptcp_finish

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Date:   Mon, 12 Jul 2021 08:08:00 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jianguo Wu <wujianguo@...natelecom.cn>,
        Mat Martineau <mathew.j.martineau@...ux.intel.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 320/593] mptcp: generate subflow hmac after mptcp_finish_join()

From: Jianguo Wu <wujianguo@...natelecom.cn>

[ Upstream commit 0a4d8e96e4fd687af92b961d5cdcea0fdbde05fe ]

For outgoing subflow join, when recv SYNACK, in subflow_finish_connect(),
the mptcp_finish_join() may return false in some cases, and send a RESET
to remote, and no local hmac is required.
So generate subflow hmac after mptcp_finish_join().

Fixes: ec3edaa7ca6c ("mptcp: Add handling of outgoing MP_JOIN requests")
Signed-off-by: Jianguo Wu <wujianguo@...natelecom.cn>
Signed-off-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/mptcp/subflow.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 851fb3d8c791..bba5696fee36 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -338,15 +338,15 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 			goto do_reset;
 		}
 
+		if (!mptcp_finish_join(sk))
+			goto do_reset;
+
 		subflow_generate_hmac(subflow->local_key, subflow->remote_key,
 				      subflow->local_nonce,
 				      subflow->remote_nonce,
 				      hmac);
 		memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN);
 
-		if (!mptcp_finish_join(sk))
-			goto do_reset;
-
 		subflow->mp_join = 1;
 		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
 	} else if (mptcp_check_fallback(sk)) {
-- 
2.30.2