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From: Bryam Vargas <hexlabsecurity@proton.me>
To: Matthieu Buffet <matthieu@buffet.re>
Cc: "Mickaël Salaün" <mic@digikod.net>,
	"Günther Noack" <gnoack@google.com>,
	"Mikhail Ivanov" <ivanov.mikhail1@huawei-partners.com>,
	"Paul Moore" <paul@paul-moore.com>,
	"Eric Dumazet" <edumazet@google.com>,
	"Neal Cardwell" <ncardwell@google.com>,
	linux-security-module@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 1/2] landlock: fix TCP Fast Open connection bypass
Date: Fri, 19 Jun 2026 01:39:06 +0000	[thread overview]
Message-ID: <20260619013859.268003-1-hexlabsecurity@proton.me> (raw)
In-Reply-To: <e0c7b502-931e-481e-89b0-b47687d2b942@buffet.re>

Thanks, that settles it: MPTCP is out of scope by design, not a gap.

I read 854277e2cc8c ("landlock: Fix non-TCP sockets restriction"). It
changed the sock->type != SOCK_STREAM test to !sk_is_tcp(sock->sk),
dropping SMC/MPTCP/SCTP from the TCP rights on purpose, and 3d4033985ff5
pins that with a "MPTCP actions are not restricted" selftest. So my
"|| sk_protocol == IPPROTO_MPTCP" suggestion was wrong: it would revert
that decision and break the selftest. Please disregard it.

That leaves the series complete as-is on this axis. Keeping both the v0
guard and the 2/2 selftest sk_is_tcp()-only is correct, and the
Tested-by stands for the TCP and IPv6 fast-open path the patch fixes.

Bryam


  reply	other threads:[~2026-06-19  1:39 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-16 20:16 Landlock: LANDLOCK_ACCESS_NET_CONNECT_TCP bypass via TCP Fast Open Bryam Vargas
2026-06-17 14:22 ` Mickaël Salaün
2026-06-17 18:05   ` Matthieu Buffet
2026-06-17 18:05     ` [RFC PATCH 1/2] landlock: fix TCP Fast Open connection bypass Matthieu Buffet
2026-06-18  1:25       ` Bryam Vargas
2026-06-19  0:34         ` Matthieu Buffet
2026-06-19  1:39           ` Bryam Vargas [this message]
2026-06-17 18:05     ` [RFC PATCH 2/2] selftests/landlock: Add test for TCP fast open Matthieu Buffet

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