From patchwork Tue Jun 15 03:02:25 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jianguo Wu X-Patchwork-Id: 12320511 X-Patchwork-Delegate: mat@martineau.name Received: from m12-14.163.com (m12-14.163.com [220.181.12.14]) by smtp.subspace.kernel.org (Postfix) with ESMTP id CB4B86D0E for ; Tue, 15 Jun 2021 03:18:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-Id; bh=fc7DM/nfCFc+ak5COu 7ol9l9KbcCLFVkNjQTdR7mWSs=; b=hgp9U0pus60WtNdRvdQjkU0ua5CyOa2d5U iWkFVlNuJswaulY7D8Fo2sRohdTy1D4UwYTdQRO6CFZd6nLCdhixIApXwAIYxzgg t/9ztWx1Ul3jGcGodHBx4P8Swu0szLlzDalrQk0P2/PUbrerw1BJzWzUSVONG1i5 urS57+/RI= Received: from localhost.localdomain.localdomain (unknown [110.80.1.45]) by smtp10 (Coremail) with SMTP id DsCowAC3_2NMGMhgphfqOw--.24172S5; Tue, 15 Jun 2021 11:02:38 +0800 (CST) From: wujianguo106@163.com To: mptcp@lists.linux.dev Cc: pabeni@redhat.com, fw@strlen.de Subject: [PATCH v4 3/4] mptcp: fix syncookie process if mptcp can not_accept new subflow Date: Tue, 15 Jun 2021 11:02:25 +0800 Message-Id: <1623726146-5911-4-git-send-email-wujianguo106@163.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1623726146-5911-1-git-send-email-wujianguo106@163.com> References: <1623726146-5911-1-git-send-email-wujianguo106@163.com> X-CM-TRANSID: DsCowAC3_2NMGMhgphfqOw--.24172S5 X-Coremail-Antispam: 1Uf129KBjvJXoWxAryrJFW3Kr1rCFW5GF45Wrg_yoW5Ww43pr 4UXrWxtr1fJFy3GF4ftr4DZw1UWFZYyrZxJa15K347Awn8Zws3Kry8KF1xKryxCFs7GFy5 Xr4vq3WqvFnrCaDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jZfH8UUUUU= X-Originating-IP: [110.80.1.45] X-CM-SenderInfo: 5zxmxt5qjx0iiqw6il2tof0z/xtbB9w6ykF2MZQbyIAAAs7 X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: From: Jianguo Wu Lots of "TCP: tcp_fin: Impossible, sk->sk_state=7" in client side when doing stress testing. There are at least two cases may trigger this warning: 1.mptcp is in syncookie, and server recv MP_JOIN SYN request, in subflow_check_req(), the mptcp_can_accept_new_subflow() return false, so subflow_init_req_cookie_join_save() isn't called, i.e. not store the data present in the MP_JOIN syn request and the random nonce in hash table - join_entries[], but still send synack. When recv 3rd-ack, mptcp_token_join_cookie_init_state() will return false, and 3rd-ack is dropped, then if mptcp conn is closed by client, client will send a DATA_FIN and a MPTCP FIN, the DATA_FIN doesn't have MP_CAPABLE or MP_JOIN, so mptcp_subflow_init_cookie_req() will return 0, and pass the cookie check, MP_JOIN request is fallback to normal TCP. Server will send a TCP FIN if closed, in client side, when process TCP FIN, it will do reset, the code path is: tcp_data_queue()->mptcp_incoming_options() ->check_fully_established()->mptcp_subflow_reset(). mptcp_subflow_reset() will set sock state to TCP_CLOSE, so tcp_fin will hit TCP_CLOSE, and print the warning. 2.mptcp is in syncookie, and server recv 3rd-ack, in mptcp_subflow_init_cookie_req(), mptcp_can_accept_new_subflow() return false, and subflow_req->mp_join is not set to 1, so in subflow_syn_recv_sock() will not reset the MP_JOIN subflow, but fallback to normal TCP, and then the same thing happens when server will send a TCP FIN if closed. For case1, subflow_check_req() return -EPERM, then tcp_conn_request() will drop MP_JOIN SYN. For case2, let subflow_syn_recv_sock() call mptcp_can_accept_new_subflow(), and do fatal fallback, send reset. Fixes: 9466a1ccebbe("mptcp: enable JOIN requests even if cookies are in use") Signed-off-by: Jianguo Wu --- 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 75ed530706c0..6d98e19a20aa 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -224,6 +224,8 @@ static int subflow_check_req(struct request_sock *req, if (unlikely(req->syncookie)) { if (mptcp_can_accept_new_subflow(subflow_req->msk)) subflow_init_req_cookie_join_save(subflow_req, skb); + else + return -EPERM; } pr_debug("token=%u, remote_nonce=%u msk=%p", subflow_req->token, @@ -263,9 +265,7 @@ int mptcp_subflow_init_cookie_req(struct request_sock *req, if (!mptcp_token_join_cookie_init_state(subflow_req, skb)) return -EINVAL; - if (mptcp_can_accept_new_subflow(subflow_req->msk)) - subflow_req->mp_join = 1; - + subflow_req->mp_join = 1; subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1; }