From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-42ab.mail.infomaniak.ch (smtp-42ab.mail.infomaniak.ch [84.16.66.171]) (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 695E0388E42 for ; Tue, 24 Mar 2026 15:11:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=84.16.66.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774365112; cv=none; b=do6AwaN5arHTOCJD6U/YOBCCmz0cegw11r6xet0oJMoDA26aqqf8N5QnFtk1iRVtKoS8tdhuWS+ngNA6YPn0Jf8L1vOICG4vkkDiaVEbBECoPwLWhefBIFxDNolGEpGpOLWgHV3rYnJMnKs/kFZQwp2dzSGDlpxWj2tULr/FmAo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774365112; c=relaxed/simple; bh=c2gb/FNBBagWrS1XVKZ3P96gfYZYYcvX2+2LtJPkQxk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=BcPU2zTy/B2SdTSy96mOziLkgfrmu5E5K5dX64XOrJDF4p8yC5ZdMuPXGDb/0HAMfDCPi39TwMkdWSlwgMdsCGr+7Auh6F5+vX7SaJd8KfE3T5VJyD7958ilXM12TvvadJgNyI37wrKx0Sn2b58xVsEPDykokYddp4pNy2wE0QE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=digikod.net; spf=pass smtp.mailfrom=digikod.net; dkim=pass (1024-bit key) header.d=digikod.net header.i=@digikod.net header.b=fYStLhUi; arc=none smtp.client-ip=84.16.66.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=digikod.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=digikod.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=digikod.net header.i=@digikod.net header.b="fYStLhUi" Received: from smtp-4-0000.mail.infomaniak.ch (smtp-4-0000.mail.infomaniak.ch [10.7.10.107]) by smtp-4-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4fgCzL4N8tz12Vc; Tue, 24 Mar 2026 16:06:06 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=digikod.net; s=20191114; t=1774364766; bh=Jmu6wWTlmezDVq+veZoOrDH/dJwq3wLCXrKIoQI3uxo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fYStLhUiScxTb6yLxOIdLcAzjcTJmG5YGmMFzQCEhVNeQCY+CsJJtrmpCHFosEMye 2nZff9Ve9VrT03IDW6gOHpyWN8AX1MMPz/eRkPkgaMlkxzdi+QBhZ7zKTdw3SYIpmp TcEaFVoJYPLkHN8jCRmrDO5LJfQbs2Lcb0enSoDc= Received: from unknown by smtp-4-0000.mail.infomaniak.ch (Postfix) with ESMTPA id 4fgCzK5C43zpXq; Tue, 24 Mar 2026 16:06:05 +0100 (CET) Date: Tue, 24 Mar 2026 16:06:01 +0100 From: =?utf-8?Q?Micka=C3=ABl_Sala=C3=BCn?= To: =?utf-8?Q?G=C3=BCnther?= Noack Cc: "Panagiotis \"Ivory\" Vasilopoulos" , Jonathan Corbet , Shuah Khan , linux-security-module@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Dan Cojocaru Subject: Re: [PATCH v4] landlock: Expand restrict flags example for ABI version 8 Message-ID: <20260324.aqu5Eic7Thee@digikod.net> References: <20260304-landlock-docs-add-tsync-example-v4-1-819a276f05c5@n0toose.net> <20260323.sheiHaR5uRoo@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-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Infomaniak-Routing: alpha On Tue, Mar 24, 2026 at 10:48:29AM +0100, Günther Noack wrote: > Hello! > > On Mon, Mar 23, 2026 at 07:56:21PM +0100, Mickaël Salaün wrote: > > Thanks! I pushed your patch in next with a minor fix. > > > > Günther, does it look good to you? > > > > On Wed, Mar 04, 2026 at 07:13:04PM +0100, Panagiotis "Ivory" Vasilopoulos wrote: > > > Add LANDLOCK_RESTRICT_SELF_TSYNC to the backwards compatibility example > > > for restrict flags. This introduces completeness, similar to that of > > > the ruleset attributes example. However, as the new example can impact > > > enforcement in certain cases, an appropriate warning is also included. > > > > > > Additionally, I modified the two comments of the example to make them > > > more consistent with the ruleset attributes example's. > > > > > > Signed-off-by: Panagiotis 'Ivory' Vasilopoulos > > > Co-developed-by: Dan Cojocaru > > > Signed-off-by: Dan Cojocaru > > > --- > > > Changes in v4: > > > - Make warning somewhat more terse, merge comments. > > > - Remove some sensationalization. ("Don't copy-paste this just yet!") > > > - Apply Günther's suggestion (v3 "recycled" some phrases, was long) > > > - ... but also retain some of the wording on ABI differences > > > - Provide a brief overview that contextualizes the example further: > > > - Clarify the difference behind ABI < 8 & ABI v8, to avoid > > > misunderstandings on which option is the default. > > > - Make "linear reading" easier. > > > - Based on Mickaël's feedback: Avoid cans of worms w.r.t. use cases > > > - Link to v3: https://lore.kernel.org/r/20260228-landlock-docs-add-tsync-example-v3-1-140ab50f0524@n0toose.net > > > > > > Changes in v3: > > > - Add __attribute__((fallthrough)) like in earlier example. > > > - Improve comment for LANDLOCK_RESTRICT_SELF_TSYNC (ABI < 8) example. > > > - Add relevant warning for ABI < 8 example based on Günther's feedback. > > > - Link to v2: https://lore.kernel.org/r/20260221-landlock-docs-add-tsync-example-v2-1-60990986bba5@n0toose.net > > > > > > Changes in v2: > > > - Fix formatting error. > > > - Link to v1: https://lore.kernel.org/r/20260221-landlock-docs-add-tsync-example-v1-1-f89383809eb4@n0toose.net > > > --- > > > Documentation/userspace-api/landlock.rst | 22 ++++++++++++++++++---- > > > 1 file changed, 18 insertions(+), 4 deletions(-) > > > > > > diff --git a/Documentation/userspace-api/landlock.rst b/Documentation/userspace-api/landlock.rst > > > index 13134bccdd39d78ddce3daf454f32dda162ce91b..64c7138a788d74f99da0a71428da392b3d873bf8 100644 > > > --- a/Documentation/userspace-api/landlock.rst > > > +++ b/Documentation/userspace-api/landlock.rst > > > @@ -196,13 +196,27 @@ similar backwards compatibility check is needed for the restrict flags > > > (see sys_landlock_restrict_self() documentation for available flags): > > > > > > .. code-block:: c > > > - > > > - __u32 restrict_flags = LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON; > > > - if (abi < 7) { > > > - /* Clear logging flags unsupported before ABI 7. */ > > > + __u32 restrict_flags = > > > + LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON | > > > + LANDLOCK_RESTRICT_SELF_TSYNC; > > > + switch (abi) { > > > + case 1 ... 6: > > > + /* Clear logging flags unsupported for ABI < 7 */ > > > restrict_flags &= ~(LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF | > > > LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON | > > > LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF); > > > + __attribute__((fallthrough)); > > > + case 7: > > > + /* > > > + * Removes multithreaded enforcement flag unsupported for ABI < 8 > > > + * > > > + * WARNING: Without this flag, calling landlock_restrict_self(2) is > > > + * only equivalent if the calling process is single-threaded. Below > > > + * ABI v8 (and as of ABI v8, when not using this flag), a Landlock > > > + * policy would only be enforced for the calling thread and its > > > + * children (and not for all threads, including parents and siblings). > > > + */ > > > + restrict_flags &= ~LANDLOCK_RESTRICT_SELF_TSYNC; > > > } > > > > > > The next step is to restrict the current thread from gaining more privileges > > > > > > --- > > > base-commit: ceb977bfe9e8715e6cd3a4785c7aab8ea5cd2b77 > > > change-id: 20260221-landlock-docs-add-tsync-example-e8fd5c64a366 > > > > > > Best regards, > > > -- > > > Panagiotis "Ivory" Vasilopoulos > > > > > > > > Apologies for the delay, this must have slipped through the cracks. > Thanks for bringing it up again. Yes, this looks good. > > Signed-off-by: Günther Noack Shouldn't it be a Reviewed-by?