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 12:47:26 +0100 [thread overview]
Message-ID: <7dfda5bb-665c-4068-acd4-795972da63e8@redhat.com> (raw)
In-Reply-To: <c10939d2-437e-47fb-81e9-05723442c935@redhat.com>
On 10/28/25 12:30 PM, Paolo Abeni wrote:
> 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?
Matttbe explained off-list the details of how that could happen. I think
the commit message here must be more verbose to explain clearly the
whys, even to those non proficient in sockmap like me.
Thanks,
Paolo
next prev parent reply other threads:[~2025-10-28 11:47 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
2025-10-28 11:47 ` Paolo Abeni [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=7dfda5bb-665c-4068-acd4-795972da63e8@redhat.com \
--to=pabeni@redhat.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=davem@davemloft.net \
--cc=eddyz87@gmail.com \
--cc=edumazet@google.com \
--cc=fw@strlen.de \
--cc=geliang@kernel.org \
--cc=haoluo@google.com \
--cc=horms@kernel.org \
--cc=jakub@cloudflare.com \
--cc=jiayuan.chen@linux.dev \
--cc=john.fastabend@gmail.com \
--cc=jolsa@kernel.org \
--cc=kpsingh@kernel.org \
--cc=kuba@kernel.org \
--cc=kuniyu@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=martin.lau@linux.dev \
--cc=martineau@kernel.org \
--cc=matttbe@kernel.org \
--cc=mptcp@lists.linux.dev \
--cc=netdev@vger.kernel.org \
--cc=sdf@fomichev.me \
--cc=shuah@kernel.org \
--cc=song@kernel.org \
--cc=stable@vger.kernel.org \
--cc=willemb@google.com \
--cc=yonghong.song@linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).