From: Paolo Abeni <pabeni@redhat.com>
To: Jiayuan Chen <jiayuan.chen@linux.dev>, mptcp@lists.linux.dev
Cc: stable@vger.kernel.org, Jakub Sitnicki <jakub@cloudflare.com>,
John Fastabend <john.fastabend@gmail.com>,
Eric Dumazet <edumazet@google.com>,
Kuniyuki Iwashima <kuniyu@google.com>,
Willem de Bruijn <willemb@google.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>, Simon Horman <horms@kernel.org>,
Matthieu Baerts <matttbe@kernel.org>,
Mat Martineau <martineau@kernel.org>,
Geliang Tang <geliang@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@fomichev.me>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>, Shuah Khan <shuah@kernel.org>,
Florian Westphal <fw@strlen.de>,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
bpf@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH net v3 1/3] net,mptcp: fix proto fallback detection with BPF sockmap
Date: Tue, 28 Oct 2025 12:30:27 +0100 [thread overview]
Message-ID: <c10939d2-437e-47fb-81e9-05723442c935@redhat.com> (raw)
In-Reply-To: <20251023125450.105859-2-jiayuan.chen@linux.dev>
On 10/23/25 2:54 PM, Jiayuan Chen wrote:
> When the server has MPTCP enabled but receives a non-MP-capable request
> from a client, it calls mptcp_fallback_tcp_ops().
>
> Since non-MPTCP connections are allowed to use sockmap, which replaces
> sk->sk_prot, using sk->sk_prot to determine the IP version in
> mptcp_fallback_tcp_ops() becomes unreliable. This can lead to assigning
> incorrect ops to sk->sk_socket->ops.
I don't see how sockmap could modify the to-be-accepted socket sk_prot
before mptcp_fallback_tcp_ops(), as such call happens before the fd is
installed, and AFAICS sockmap can only fetch sockets via fds.
Is this patch needed?
/P
next prev parent reply other threads:[~2025-10-28 11:30 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-23 12:54 [PATCH net v3 0/3] mptcp: Fix conflicts between MPTCP and sockmap Jiayuan Chen
2025-10-23 12:54 ` [PATCH net v3 1/3] net,mptcp: fix proto fallback detection with BPF sockmap Jiayuan Chen
2025-10-23 14:10 ` Matthieu Baerts
2025-10-23 14:38 ` Jiayuan Chen
2025-10-28 11:30 ` Paolo Abeni [this message]
2025-10-28 11:47 ` Paolo Abeni
2025-11-03 12:45 ` Jiayuan Chen
2025-11-03 12:44 ` Jiayuan Chen
2025-10-23 12:54 ` [PATCH net v3 2/3] bpf,sockmap: disallow MPTCP sockets from sockmap Jiayuan Chen
2025-10-28 12:03 ` Paolo Abeni
2025-11-03 12:52 ` Jiayuan Chen
2025-10-23 12:54 ` [PATCH net v3 3/3] selftests/bpf: Add mptcp test with sockmap Jiayuan Chen
2025-10-23 14:10 ` [PATCH net v3 0/3] mptcp: Fix conflicts between MPTCP and sockmap Matthieu Baerts
2025-10-24 4:13 ` Jiayuan Chen
2025-10-28 17:26 ` Matthieu Baerts
2025-11-03 12:34 ` Jiayuan Chen
2025-11-03 15:53 ` Matthieu Baerts
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