From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A79751494DC for ; Tue, 25 Jun 2024 09:49:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719309000; cv=none; b=GCGUwkibfIxsFOXKgYBsNY4tMpdlcm06+mVMWK8aynoimccbKrULFGvLyJVIbvAfIRy9TVYZZ7zEJKKLAYAfY5aX2Y8oxmwgcfulxyxgUwckOY1Pq3ad2olCUdTaTdo6KO6AQE5RjFXodNAWZjOIvs4iOaD6bKaxR4JDZD/KCLQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719309000; c=relaxed/simple; bh=A03mgbNmGjbLch5TeEoOwpCQwRBej8p0QYPVVQHgDE4=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=OUzM7TLpH0aUGtMi599FzPZ+daNFJ+5xmx+3nOYtfyJ2GdGEAnOC3BzLYPj7OsqWEXQnALkMfnNXM5ZyNDdPBpSgDV+yWW+jW4xgODP7v+hrrrVXOJIvKRd1vVAWI89aplF7eNnN8LnWcYg5fhEXdArR0My/SgmsY7H1cg/RgpE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=gwDD+To7; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="gwDD+To7" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1719308997; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=psNMkpNTGDQzWk3QAta1KKRmCYENugFYCSyQR3BM+L8=; b=gwDD+To7Jvbj+xfkaXlmrAVKo37hS9MZr0Nu0vBJN+glXrrQMNu/cVpKYML+F7ISW7JpC5 jsmuY9oLjmyt+lwhNrwK5gE7tJ5BD+4HqsyefeMxGq5lNizf5QeZYI0MgV02V44wDzLctr kR9i8EOU2Z24By3BmckPi0v9v5ynpaQ= Received: from mail-lf1-f70.google.com (mail-lf1-f70.google.com [209.85.167.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-107-uSL6hwXHMmClnMX_nd0hdg-1; Tue, 25 Jun 2024 05:49:55 -0400 X-MC-Unique: uSL6hwXHMmClnMX_nd0hdg-1 Received: by mail-lf1-f70.google.com with SMTP id 2adb3069b0e04-52cd6d7a7fdso437805e87.3 for ; Tue, 25 Jun 2024 02:49:55 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1719308994; x=1719913794; h=mime-version:user-agent:content-transfer-encoding:autocrypt :references:in-reply-to:date:cc:to:from:subject:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=psNMkpNTGDQzWk3QAta1KKRmCYENugFYCSyQR3BM+L8=; b=OkQ9ikvYkRsZkanD8+8yjg3Jru4ot6SD0jpV4ru/8ech/39/d6INYoy/uhdqFDBe/a zbhTa7nGxcRbyng49po0bnQTutuKXgZw91CFNfshYDeEtsEaSjH+ndxR97018X9c8Egl tsmkTqRbmA1qoMdh+ajTm1+nY+HD6PFi2mY+RhfEaqzR1kxth4xF9TNfaO/Uk1oxGlSn 3/iNwnS2Xxhz4v3+acTqRZ1sP0GBss66vNDqcs1olxclX3TD0h3U7y4JbQKjv30ldoYC abCeQTkTwnP/sAySl6br5VLHxR5xo5Yb5YngA3AVU+oJ+Jy6bnNW5uYqcqEbKrZ87L2l WGKQ== X-Forwarded-Encrypted: i=1; AJvYcCX5zWYZGPu23hQdAgyJOGCcEtRV6KQ1e17lJw6oF+EQvDBiwIVfRhjbGCovws/6bFnv8H6R20hMa2iCjgYiiEc1jiMrcvyf X-Gm-Message-State: AOJu0YxqhwfvC+0BkvulHzC40yPqyH5gJVgx0JEZcqS0J0s1a6umEUrm o4/vrRrRmlPLXyX6YMRNIHdZA1RRn55/6Y37SRZ5MQQvGmyVQTvhgqOIURkXwvcvWDqpYqC7x1Z YRk1RcRWdTAddyqqljrZpT1C99o+fgQ95xr+VtZSH2fKFIBRBHsauow== X-Received: by 2002:a05:6512:3484:b0:52c:df28:de54 with SMTP id 2adb3069b0e04-52cdf28def2mr3963806e87.4.1719308993960; Tue, 25 Jun 2024 02:49:53 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFpr5j+DHVEDwph2UELN1gJ7+NW8BC0MPTSCjKHUvq7DvAMIqxUYK/rpfqmyzXv4fBz+CiemA== X-Received: by 2002:a05:6512:3484:b0:52c:df28:de54 with SMTP id 2adb3069b0e04-52cdf28def2mr3963781e87.4.1719308993538; Tue, 25 Jun 2024 02:49:53 -0700 (PDT) Received: from gerbillo.redhat.com ([2a0d:3341:b0ae:da10::f71]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4247d0b636bsm210282705e9.6.2024.06.25.02.49.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 25 Jun 2024 02:49:53 -0700 (PDT) Message-ID: <35f497afd90fe16ba1408f25ea1ff62af6a73a90.camel@redhat.com> Subject: Re: [PATCH net v4] Fix race for duplicate reqsk on identical SYN From: Paolo Abeni To: luoxuanqiang , kuniyu@amazon.com, edumazet@google.com, kuba@kernel.org, davem@davemloft.net Cc: dccp@vger.kernel.org, dsahern@kernel.org, fw@strlen.de, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, alexandre.ferrieux@orange.com Date: Tue, 25 Jun 2024 11:49:51 +0200 In-Reply-To: <20240621013929.1386815-1-luoxuanqiang@kylinos.cn> References: <20240621013929.1386815-1-luoxuanqiang@kylinos.cn> Autocrypt: addr=pabeni@redhat.com; prefer-encrypt=mutual; keydata=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 7ZxN9ZsDL38qVIuFkSpgMZCiUHdxBC11J8nbBSLlpnc924UAyr5XrGA99 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 iWjoCy8L35zPqR5TV+f5WR5hTVCqmLHSgm1jxwKhPg9L+GfuE4d0SWd84y 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 sD2W1U7eyLdm/jCgticGDsRtweytsgCSYfbz0gdgUuL3EBYN3JLbAU+UZpy 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.4 (3.50.4-1.fc39) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Fri, 2024-06-21 at 09:39 +0800, luoxuanqiang wrote: > When bonding is configured in BOND_MODE_BROADCAST mode, if two identical > SYN packets are received at the same time and processed on different CPUs= , > it can potentially create the same sk (sock) but two different reqsk > (request_sock) in tcp_conn_request(). >=20 > These two different reqsk will respond with two SYNACK packets, and since > the generation of the seq (ISN) incorporates a timestamp, the final two > SYNACK packets will have different seq values. >=20 > The consequence is that when the Client receives and replies with an ACK > to the earlier SYNACK packet, we will reset(RST) it. >=20 > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D >=20 > This behavior is consistently reproducible in my local setup, > which comprises: >=20 > | NETA1 ------ NETB1 | > PC_A --- bond --- | | --- bond --- PC_B > | NETA2 ------ NETB2 | >=20 > - PC_A is the Server and has two network cards, NETA1 and NETA2. I have > bonded these two cards using BOND_MODE_BROADCAST mode and configured > them to be handled by different CPU. >=20 > - PC_B is the Client, also equipped with two network cards, NETB1 and > NETB2, which are also bonded and configured in BOND_MODE_BROADCAST mode= . >=20 > If the client attempts a TCP connection to the server, it might encounter > a failure. Capturing packets from the server side reveals: >=20 > 10.10.10.10.45182 > localhost: Flags [S], seq 320236027, > 10.10.10.10.45182 > localhost: Flags [S], seq 320236027, > localhost > 10.10.10.10.45182: Flags [S.], seq 2967855116, > localhost > 10.10.10.10.45182: Flags [S.], seq 2967855123, <=3D=3D > 10.10.10.10.45182 > localhost: Flags [.], ack 4294967290, > 10.10.10.10.45182 > localhost: Flags [.], ack 4294967290, > localhost > 10.10.10.10.45182: Flags [R], seq 2967855117, <=3D=3D > localhost > 10.10.10.10.45182: Flags [R], seq 2967855117, >=20 > Two SYNACKs with different seq numbers are sent by localhost, > resulting in an anomaly. >=20 > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D >=20 > The attempted solution is as follows: > Add a return value to inet_csk_reqsk_queue_hash_add() to confirm if the > ehash insertion is successful (Up to now, the reason for unsuccessful > insertion is that a reqsk for the same connection has already been > inserted). If the insertion fails, release the reqsk. >=20 > Due to the refcnt, Kuniyuki suggests also adding a return value check > for the DCCP module; if ehash insertion fails, indicating a successful > insertion of the same connection, simply release the reqsk as well. >=20 > Simultaneously, In the reqsk_queue_hash_req(), the start of the > req->rsk_timer is adjusted to be after successful insertion. >=20 > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Just after applying the patch I wondered if the issue addressed here should be observable only after commit e994b2f0fb92 ("tcp: do not lock listener to process SYN packets")? In practice it should not matter as the latter commit it's older than the currently older LST, but I'm wondering if I read the things correctly? Thanks! Paolo