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 D4A3F2FBDE9; Tue, 14 Oct 2025 15:27:47 +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=1760455667; cv=none; b=oZL2i22CowHsgSxrUmIU8GBizHYcKYAi2yqBAUmY/eZy5VJ8+7DQd1D1axrkt+sse3WmKsSyN8NuJ3C3JCnd3yrgCQYFttls4Gj+VPW22s03M//ej5V9mNJExtlId2KA6dks0nWU5lJByPLNDFEBVEkfjQwzKRqEVZa3BqWDAAk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760455667; c=relaxed/simple; bh=rcbQ/4zVKPt71QNu9FJMs9RnxpPz+SCqZaHgRW8i6xw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=nNwWdP38uuejwvEmHYAxwPBTph2BDpcrJnTBbjoa26HfqcYQGzdULa+oQmD6UWsaEAhmTtHUffgCKOtdp+WTcGDhocl4juRdbx6ntyidsMJgMjPuQLdnBuKgS3GV9JvyYwXE2j+XbixN3lKmUFDrhY4DBUYuKf3G7LqhDxf31GY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cNgSryB+; 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="cNgSryB+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9E376C4CEE7; Tue, 14 Oct 2025 15:27:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1760455667; bh=rcbQ/4zVKPt71QNu9FJMs9RnxpPz+SCqZaHgRW8i6xw=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=cNgSryB+BZuqNdIe8HWdP29pEuHcFy+pTb7q0EsxHOIKC1M6hctcZ3JfySAzPW7gv yq9ea8HY+WFyN9Oi98YXBp0KVGTZW6D+mUU6BHHnUobvgZp+3YlFNfukqendjM9A+m 4ZbR2e4Eu4INVDKLAj1Xg7BX4HuuWI0HwRdMAG+d9eQmvAFSg4SLUhKQDG0DgKuoAC BATlcMW2YW8xmJy5cBIfgN5irj6eWgttXzmvlyPnPa9fozv1ZVEHIoLFsFMVyFb0MN JAyWg9fSI09X8+pM7YNyPYqFPJ5FdKFW7yfNjdWxM7ZXppDypjc0IIYmYcKJGs5hMI wgDUlgv8hkx5Q== Message-ID: Date: Tue, 14 Oct 2025 17:27:41 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH net-next v1] mptcp: fix incorrect IPv4/IPv6 check Content-Language: en-GB, fr-BE To: Jiayuan Chen Cc: Mat Martineau , Geliang Tang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Davide Caratti , netdev@vger.kernel.org, mptcp@lists.linux.dev, linux-kernel@vger.kernel.org References: <20251014122619.316463-1-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: <20251014122619.316463-1-jiayuan.chen@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Jiayuan, Thank you for sharing this patch! On 14/10/2025 14:26, Jiayuan Chen wrote: > When MPTCP falls back to normal TCP, it needs to reset proto_ops. However, > for sockmap and TLS, they have their own custom proto_ops, so simply > checking sk->sk_prot is insufficient. > > For example, an IPv6 request might incorrectly follow the IPv4 code path, > leading to kernel panic. Did you experiment issues, or is it a supposition? If yes, do you have traces containing such panics (or just a WARN()?), and ideally the userspace code that was leading to this? What is unclear to me is how you got an MPTCP + TLS + sockmap socket. And if yes, can we set sk_socket->ops to inet(6)_stream_ops and nothing else without having any other issues? And do we maybe have to update some code in subflow.c also looking at sk->sk_prot? I guess no because there, the socket is created by MPTCP, and it should be set to tcp(v6)_prot. Except if there is some BPF code that can change that? > Note that Golang has enabled MPTCP by default [1] > > [1] https://go-review.googlesource.com/c/go/+/607715 > > Fixes: 8e2b8a9fa512 ("mptcp: don't overwrite sock_ops in mptcp_is_tcpsk()") If I understand the issue correctly, was it not present from the beginning, before the mentioned commit? > Signed-off-by: Jiayuan Chen > --- > net/mptcp/protocol.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c > index 0292162a14ee..efcdaeff91f8 100644 > --- a/net/mptcp/protocol.c > +++ b/net/mptcp/protocol.c > @@ -62,10 +62,10 @@ static u64 mptcp_wnd_end(const struct mptcp_sock *msk) > static const struct proto_ops *mptcp_fallback_tcp_ops(const struct sock *sk) > { > #if IS_ENABLED(CONFIG_MPTCP_IPV6) > - if (sk->sk_prot == &tcpv6_prot) > + if (sk->sk_family == AF_INET6) sk_prot was proving it was a TCP + IPv4/6 socket, and then that's OK to set inet(6)_stream_ops. I guess we could only check the family, but, can we always return inet(6)_stream_ops no matter what sk->sk_prot is? If the protocol has been modified, the stream one has maybe been modified too, no? > return &inet6_stream_ops; > #endif > - WARN_ON_ONCE(sk->sk_prot != &tcp_prot); > + WARN_ON(sk->sk_family != AF_INET); Please keep the WARN_ON_ONCE(). Maybe we should not return inet_stream_ops in case the previous condition was wrong, and not change sk_socket->ops. > return &inet_stream_ops; > } Note about the subject: if it is a fix for an older commit, it should target 'net', not 'net-next' (+ cc stable). Can you also have a clearer subject mentioning 'proto' and 'fallback' please? Cheers, Matt -- Sponsored by the NGI0 Core fund.