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 9C46711CAF; Sun, 30 Nov 2025 16:21:17 +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=1764519677; cv=none; b=EiKczZoQnq0M9Z3W00QyX8aHErWYavtff1m7hqVaEA69DKryO7NWCgJvAb5MaNcLbKp6BHsgN0XuyjxcbmrhHiO3m7CG6UaIr5A0biBafRyygIstDwBY/pI8wnB9psLG/rP6q2VZkud91sCpjqDz968b30KiXQ4p822JDoHVKC8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764519677; c=relaxed/simple; bh=QIGxXzOXgetKMboQBkk6r8HvQViU7hOvjX/Fh/C0908=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=qrDX3GRpRfV/HEQJ3RgThw/aS1RozaKPuu9c6pE6q4ubLicjQ7QRsAwR38HUDscrLmteEKEX15J0xk3FiQhwz3t9drMRS3wzGqYqp+fzyULrORDgiIUkpQ655DelndS/PAvpCb130th0rjCjQZr9bJb38iRhBbzbqrda170sw+k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=iaxI8nW3; 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="iaxI8nW3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9D61DC4CEF8; Sun, 30 Nov 2025 16:21:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764519676; bh=QIGxXzOXgetKMboQBkk6r8HvQViU7hOvjX/Fh/C0908=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=iaxI8nW3Djp1jtV77hWZrTXMreN1mD4Y9zujgroegOO5eQgyGoSvUI5YI6ZrF4lrn 8jc8qdEWsHfaEIg5i0Si6z7xDisNld5v/HSI3GYNMs6B3ebfxn6La1qWHE7gCcP3RR gu4TUahjcwk4ZSL2vGXeD3tfuLyTN8872Oh4+zXZjfdhEt1fIg4Q/QqTCFS5ChGVO7 228LesFc5lPIi8GXPM1jr7C/FVtsZ2mBd6f+XPieHeRZ7f5gdoICrfr69BUzBYmdtE wRGHQF4hGXWTBlXD9TjUDdpnSdz3qrvnRE3ZX/aO66xnEh8Ly4cVTXtyzeddBt8cjN yBoJOnoyXW1Xw== Message-ID: Date: Sun, 30 Nov 2025 17:21:13 +0100 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH 6.1.y v1 2/2] net,mptcp: fix proto fallback detection with BPF Content-Language: en-GB, fr-BE To: Jiayuan Chen , stable@vger.kernel.org, mptcp@lists.linux.dev, sashal@kernel.org, gregkh@linuxfoundation.org Cc: Jakub Sitnicki References: <20251130032303.324510-1-jiayuan.chen@linux.dev> <20251130032303.324510-3-jiayuan.chen@linux.dev> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Jiayuan, On 30/11/2025 04:23, 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. (...) > diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c > index 1dbc62537259..13e3510e6c8f 100644 > --- a/net/mptcp/protocol.c > +++ b/net/mptcp/protocol.c > @@ -79,8 +79,9 @@ static u64 mptcp_wnd_end(const struct mptcp_sock *msk) > static bool mptcp_is_tcpsk(struct sock *sk) > { > struct socket *sock = sk->sk_socket; > + unsigned short family = READ_ONCE(sk->sk_family); > > - if (unlikely(sk->sk_prot == &tcp_prot)) { > + if (unlikely(family == AF_INET)) { > /* we are being invoked after mptcp_accept() has > * accepted a non-mp-capable flow: sk is a tcp_sk, > * not an mptcp one. > @@ -91,7 +92,7 @@ static bool mptcp_is_tcpsk(struct sock *sk) > sock->ops = &inet_stream_ops; > return true; > #if IS_ENABLED(CONFIG_MPTCP_IPV6) > - } else if (unlikely(sk->sk_prot == &tcpv6_prot)) { > + } else if (unlikely(family == AF_INET6)) { These modifications here break MPTCP: this function (mptcp_is_tcpsk) is there to check if the socket is a "plain" TCP one (return "true") or an MPTCP one (return "false"). If it is not an MPTCP one, the sock ops is modified. Here, you are saying: any IPv4 or IPv6 socket is a "plain" TCP one, never an MPTCP socket then. I suggest adding ... if (sk->sk_protocol == IPPROTO_MPTCP) return false; ... at the beginning of this function. I'm planning to send a patch later on including this check. Once it is sent, do you mind checking it with sockmap if you have the setup available, please? Cheers, Matt -- Sponsored by the NGI0 Core fund.