From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 171E0330B3E; Tue, 11 Nov 2025 10:35:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762857328; cv=none; b=DuPzpecl8i4m6l5aguOm17riHWsdhCTt40BI8pZ4koCK7+Rb8JCxAUY1jiswYDLpYwnOuDzWTDbAiN95KfLEXTFaGEKkSxb2KD8g+L2/feWF+2X+fEs5aC4016UXR+1Cn5d+I5tJlmqTZJWtBrpWI+aRrbYrs+tVZ4ZLb9rS3Do= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762857328; c=relaxed/simple; bh=6klGeljGlw68LqBwaAYWoYFCW3C+WtLq3LWOJjf2a4Q=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=g/QaOfDeTSQbcRKCn7zl+qt65lbGkGEG4ftHblVLMVoro5T8T6v3c8RkRUkJCcCVZ6rWJ049eVRt4uUZa76rxop2Lw2qhIAfJWAYRc0J5LjT5ZXB9KZRMjoYqmX5pKGIrwktmaZSyqwsTOhk7zHFLjNABTocWhxsJhmRfPXsu5c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cqea7ZSM; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="cqea7ZSM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E9B8C4CEF7; Tue, 11 Nov 2025 10:35:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762857327; bh=6klGeljGlw68LqBwaAYWoYFCW3C+WtLq3LWOJjf2a4Q=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=cqea7ZSMZa6ig3ryOSB46KU91Ta4nbJWfYP+VniuqlT89TOqxvaV6ELkrV7TSGZg3 Ru6GzTtp3kPxZTZ/j1EFDpesySr228Zm42Y6qh5KvWvJK/kj4h9WWQf7AwqXB0BVcu LFq1r//OPnZWpoyGwin1U/SgdYO5x5uFCWYR0oDUbvIO3DzkGDdGuvy3MTWrgOFLfE WdNibhCHo08qi7/Cf8k2vVqpYsp8q0SMp6vE5tp2QNSu7n/C6RSh6z3fvrgf+/2WWI EzC32epFrF0nOiaFvvcolYuhamZjIzQcsWNgDUYYTHYr/6oPrDt5vTdUvzHHFoA+j7 A53j9uQNhlTGA== Message-ID: Date: Tue, 11 Nov 2025 11:35:13 +0100 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH net v5 2/3] net,mptcp: fix proto fallback detection with BPF Content-Language: en-GB, fr-BE To: Jiayuan Chen , mptcp@lists.linux.dev Cc: stable@vger.kernel.org, Jakub Sitnicki , Mat Martineau , Geliang Tang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Shuah Khan , Peter Krystad , Florian Westphal , Christoph Paasch , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20251111060307.194196-1-jiayuan.chen@linux.dev> <20251111060307.194196-3-jiayuan.chen@linux.dev> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; keydata= xsFNBFXj+ekBEADxVr99p2guPcqHFeI/JcFxls6KibzyZD5TQTyfuYlzEp7C7A9swoK5iCvf YBNdx5Xl74NLSgx6y/1NiMQGuKeu+2BmtnkiGxBNanfXcnl4L4Lzz+iXBvvbtCbynnnqDDqU c7SPFMpMesgpcu1xFt0F6bcxE+0ojRtSCZ5HDElKlHJNYtD1uwY4UYVGWUGCF/+cY1YLmtfb WdNb/SFo+Mp0HItfBC12qtDIXYvbfNUGVnA5jXeWMEyYhSNktLnpDL2gBUCsdbkov5VjiOX7 CRTkX0UgNWRjyFZwThaZADEvAOo12M5uSBk7h07yJ97gqvBtcx45IsJwfUJE4hy8qZqsA62A nTRflBvp647IXAiCcwWsEgE5AXKwA3aL6dcpVR17JXJ6nwHHnslVi8WesiqzUI9sbO/hXeXw TDSB+YhErbNOxvHqCzZEnGAAFf6ges26fRVyuU119AzO40sjdLV0l6LE7GshddyazWZf0iac nEhX9NKxGnuhMu5SXmo2poIQttJuYAvTVUNwQVEx/0yY5xmiuyqvXa+XT7NKJkOZSiAPlNt6 VffjgOP62S7M9wDShUghN3F7CPOrrRsOHWO/l6I/qJdUMW+MHSFYPfYiFXoLUZyPvNVCYSgs 3oQaFhHapq1f345XBtfG3fOYp1K2wTXd4ThFraTLl8PHxCn4ywARAQABzSRNYXR0aGlldSBC YWVydHMgPG1hdHR0YmVAa2VybmVsLm9yZz7CwZEEEwEIADsCGwMFCwkIBwIGFQoJCAsCBBYC AwECHgECF4AWIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZUDpDAIZAQAKCRD2t4JPQmmgcz33 EACjROM3nj9FGclR5AlyPUbAq/txEX7E0EFQCDtdLPrjBcLAoaYJIQUV8IDCcPjZMJy2ADp7 /zSwYba2rE2C9vRgjXZJNt21mySvKnnkPbNQGkNRl3TZAinO1Ddq3fp2c/GmYaW1NWFSfOmw MvB5CJaN0UK5l0/drnaA6Hxsu62V5UnpvxWgexqDuo0wfpEeP1PEqMNzyiVPvJ8bJxgM8qoC cpXLp1Rq/jq7pbUycY8GeYw2j+FVZJHlhL0w0Zm9CFHThHxRAm1tsIPc+oTorx7haXP+nN0J iqBXVAxLK2KxrHtMygim50xk2QpUotWYfZpRRv8dMygEPIB3f1Vi5JMwP4M47NZNdpqVkHrm jvcNuLfDgf/vqUvuXs2eA2/BkIHcOuAAbsvreX1WX1rTHmx5ud3OhsWQQRVL2rt+0p1DpROI 3Ob8F78W5rKr4HYvjX2Inpy3WahAm7FzUY184OyfPO/2zadKCqg8n01mWA9PXxs84bFEV2mP VzC5j6K8U3RNA6cb9bpE5bzXut6T2gxj6j+7TsgMQFhbyH/tZgpDjWvAiPZHb3sV29t8XaOF BwzqiI2AEkiWMySiHwCCMsIH9WUH7r7vpwROko89Tk+InpEbiphPjd7qAkyJ+tNIEWd1+MlX ZPtOaFLVHhLQ3PLFLkrU3+Yi3tXqpvLE3gO3LM7BTQRV4/npARAA5+u/Sx1n9anIqcgHpA7l 5SUCP1e/qF7n5DK8LiM10gYglgY0XHOBi0S7vHppH8hrtpizx+7t5DBdPJgVtR6SilyK0/mp 9nWHDhc9rwU3KmHYgFFsnX58eEmZxz2qsIY8juFor5r7kpcM5dRR9aB+HjlOOJJgyDxcJTwM 1ey4L/79P72wuXRhMibN14SX6TZzf+/XIOrM6TsULVJEIv1+NdczQbs6pBTpEK/G2apME7vf mjTsZU26Ezn+LDMX16lHTmIJi7Hlh7eifCGGM+g/AlDV6aWKFS+sBbwy+YoS0Zc3Yz8zrdbi Kzn3kbKd+99//mysSVsHaekQYyVvO0KD2KPKBs1S/ImrBb6XecqxGy/y/3HWHdngGEY2v2IP Qox7mAPznyKyXEfG+0rrVseZSEssKmY01IsgwwbmN9ZcqUKYNhjv67WMX7tNwiVbSrGLZoqf Xlgw4aAdnIMQyTW8nE6hH/Iwqay4S2str4HZtWwyWLitk7N+e+vxuK5qto4AxtB7VdimvKUs x6kQO5F3YWcC3vCXCgPwyV8133+fIR2L81R1L1q3swaEuh95vWj6iskxeNWSTyFAVKYYVskG V+OTtB71P1XCnb6AJCW9cKpC25+zxQqD2Zy0dK3u2RuKErajKBa/YWzuSaKAOkneFxG3LJIv Hl7iqPF+JDCjB5sAEQEAAcLBXwQYAQIACQUCVeP56QIbDAAKCRD2t4JPQmmgc5VnD/9YgbCr HR1FbMbm7td54UrYvZV/i7m3dIQNXK2e+Cbv5PXf19ce3XluaE+wA8D+vnIW5mbAAiojt3Mb 6p0WJS3QzbObzHNgAp3zy/L4lXwc6WW5vnpWAzqXFHP8D9PTpqvBALbXqL06smP47JqbyQxj Xf7D2rrPeIqbYmVY9da1KzMOVf3gReazYa89zZSdVkMojfWsbq05zwYU+SCWS3NiyF6QghbW voxbFwX1i/0xRwJiX9NNbRj1huVKQuS4W7rbWA87TrVQPXUAdkyd7FRYICNW+0gddysIwPoa KrLfx3Ba6Rpx0JznbrVOtXlihjl4KV8mtOPjYDY9u+8x412xXnlGl6AC4HLu2F3ECkamY4G6 UxejX+E6vW6Xe4n7H+rEX5UFgPRdYkS1TA/X3nMen9bouxNsvIJv7C6adZmMHqu/2azX7S7I vrxxySzOw9GxjoVTuzWMKWpDGP8n71IFeOot8JuPZtJ8omz+DZel+WCNZMVdVNLPOd5frqOv mpz0VhFAlNTjU1Vy0CnuxX3AM51J8dpdNyG0S8rADh6C8AKCDOfUstpq28/6oTaQv7QZdge0 JY6dglzGKnCi/zsmp2+1w559frz4+IC7j/igvJGX4KDDKUs0mlld8J2u2sBXv7CGxdzQoHaz lzVbFe7fduHbABmYz9cefQpO7wDE/Q== Organization: NGI0 Core In-Reply-To: <20251111060307.194196-3-jiayuan.chen@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Jiayuan, On 11/11/2025 07:02, Jiayuan Chen wrote: > The sockmap feature allows bpf syscall from userspace, or based > on bpf sockops, replacing the sk_prot of sockets during protocol stack > processing with sockmap's custom read/write interfaces. > ''' > tcp_rcv_state_process() > syn_recv_sock()/subflow_syn_recv_sock() > tcp_init_transfer(BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB) > bpf_skops_established <== sockops > bpf_sock_map_update(sk) <== call bpf helper > tcp_bpf_update_proto() <== update sk_prot > ''' > > When the server has MPTCP enabled but the client sends a TCP SYN > without MPTCP, subflow_syn_recv_sock() performs a fallback on the > subflow, replacing the subflow sk's sk_prot with the native sk_prot. > ''' > subflow_syn_recv_sock() > subflow_ulp_fallback() > subflow_drop_ctx() > mptcp_subflow_ops_undo_override() > ''' > > Then, this subflow can be normally used by sockmap, which replaces the > native sk_prot with sockmap's custom sk_prot. The issue occurs when the > user executes accept::mptcp_stream_accept::mptcp_fallback_tcp_ops(). > Here, it uses sk->sk_prot to compare with the native sk_prot, but this > is incorrect when sockmap is used, as we may incorrectly set > sk->sk_socket->ops. > > This fix uses the more generic sk_family for the comparison instead. > > Additionally, this also prevents a WARNING from occurring: > > result from ./scripts/decode_stacktrace.sh: > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 337 at net/mptcp/protocol.c:68 mptcp_stream_accept \ > (net/mptcp/protocol.c:4005) > Modules linked in: > ... > > PKRU: 55555554 > Call Trace: > > do_accept (net/socket.c:1989) > __sys_accept4 (net/socket.c:2028 net/socket.c:2057) > __x64_sys_accept (net/socket.c:2067) > x64_sys_call (arch/x86/entry/syscall_64.c:41) > do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94) > entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) > RIP: 0033:0x7f87ac92b83d > > ---[ end trace 0000000000000000 ]--- > > Fixes: cec37a6e41aa ("mptcp: Handle MP_CAPABLE options for outgoing connections") The previous Fixes tag you used in the previous versions was correct for this second patch: Fixes: 0b4f33def7bb ("mptcp: fix tcp fallback crash") But well, in terms of backports, that will be the same. So I guess we don't need a new version just for that. Also, I guess you missed my comments from the two previous versions: > please remove the 'net,' prefix from the title. And maybe good > to mention 'sockmap', e.g. > > mptcp: fix proto fallback detection with sockmap But same here, fine like that. > Cc: > Signed-off-by: Jiayuan Chen > Reviewed-by: Jakub Sitnicki > Reviewed-by: Matthieu Baerts (NGI0) For next time: the Signed-off-by of the sender should be at the end. So here, your SoB should go to the end, after the already sent RvB tags. But again, I don't think we need a v6 for that, except if net maintainers prefer to. Cheers, Matt -- Sponsored by the NGI0 Core fund.