From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.buffet.re (mx1.buffet.re [51.83.41.69]) (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 8CA9A371890; Wed, 17 Jun 2026 18:05:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=51.83.41.69 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781719528; cv=none; b=Ik5v9yZ2IRI1kKeRyPlOntTMOPw7dX6BSlBVT/4Ow1eZvD/idc5FZI2o1otvaN1xNNSVubDONVQgc0UAyiVWKgyEubQTSYDvcWxrwl8GigBFE6Ldvy2dtvdxKPV0QkT1kbyc6v2AASjC2q2esvk/ZWkn5Oh1rbezQWFT+9m9J1A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781719528; c=relaxed/simple; bh=/FgkYP9syTYmexU5LLVTc9MZQDepe9QOqP1BEKT3OPI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=eSzLQrdziT6l2n78DKOiiFsTLjiM8lX5MZUDykOMKkYjMoPEuxF3NTopCAAZfOIIDFv28pwtZPoaxKSuF+Ljm0icPfbCTTd2PE0qpyXmobIsjNdFi/kK1VsYjXngmXJ7we+Ig10AAsPwIP56ndTxKWivnFE8ey4ErwaopKhiuQg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=buffet.re; spf=pass smtp.mailfrom=buffet.re; dkim=pass (2048-bit key) header.d=buffet.re header.i=@buffet.re header.b=aKj6d2ZE; arc=none smtp.client-ip=51.83.41.69 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=buffet.re Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=buffet.re Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=buffet.re header.i=@buffet.re header.b="aKj6d2ZE" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=buffet.re; s=mx1; t=1781719516; bh=/FgkYP9syTYmexU5LLVTc9MZQDepe9QOqP1BEKT3OPI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aKj6d2ZEg4bn7e5Um68yvmRh3hRcvUk+nYwcRhoGLyZP0D28hCrn7oAm/beri55yQ S36NdWeq0UEUpNC173NWEPc0uv7RRFrdFNyB6QF7HxIurGE8VoUYt2wMU+Qs5zF8jy pvogavh+aP7mEqxniUegBEXjPujlMepP0cHuDIdKSy+U5re07NpmyPo25GN1Z4OD5q AgBWi/DW7xd+epaOYZRL+11Kd02fEhYB3RJsQecpDIBgRul/DB06A+4JYg6wMFSEmH xyFKZ7b9Ad6VfcowIZfUJQF/Q77GtRpPPSihuzPsZLpv7g4N949SXSDUREXNL5/pbL 1UUVX99kKdRtQ== Received: from localhost.localdomain (unknown [10.0.1.3]) by mx1.buffet.re (Postfix) with ESMTPSA id 0F41F12593E; Wed, 17 Jun 2026 20:05:16 +0200 (CEST) From: Matthieu Buffet To: Bryam Vargas Cc: =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= , =?UTF-8?q?G=C3=BCnther=20Noack?= , linux-security-module@vger.kernel.org, Mikhail Ivanov , Paul Moore , Eric Dumazet , Neal Cardwell , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Matthieu Buffet Subject: Re: Landlock: LANDLOCK_ACCESS_NET_CONNECT_TCP bypass via TCP Fast Open Date: Wed, 17 Jun 2026 20:05:22 +0200 Message-ID: <20260617180526.15627-1-matthieu@buffet.re> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260617.eemahv8ui7Ee@digikod.net> References: <20260617.eemahv8ui7Ee@digikod.net> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi, On 6/17/2026 4:22 PM, Mickaël Salaün wrote: > Thanks for the report. This was previously identified by Mikhail and > Matthieu, see the related issue: > https://github.com/landlock-lsm/linux/issues/41 (I worked on a v0 patch for that issue after I first reported it to Mickaël, missing the fact that it was already documented as a github issue. Then tried a more generic approach that failed. Here's the v0, rebased on the beggining of -next to ease backporting, it might be a good start. For instance, someone with more performance/benchmarking background might want to add an unlikely() around the MSG_FASTOPEN condition in the hot code path?) Have a nice day! Matthieu Buffet (2): landlock: fix TCP Fast Open connection bypass selftests/landlock: Add test for TCP fast open security/landlock/net.c | 17 +++ tools/testing/selftests/landlock/net_test.c | 155 ++++++++++++++++++++ 2 files changed, 172 insertions(+) base-commit: 0ce4243509d1580349dd0d50624036d6b097e958 -- 2.47.3