From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E94A81E5714; Fri, 8 May 2026 21:47:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778276827; cv=none; b=rhiI/fFvHpaswfaZUNa2jAUFEWJaP2nBCbq9nla5fDzM9zvADaZrn5vhuYwz+jlBa3QT2N+Ui7l1WqQHQx3JjLNKjBV7EB9pUDVGena0R6N3oe3KUN/Yi4h+N6ObHvHDMONoTobjoRBIssMs+c4rD2hU8mX4dYLy2MWCkTNhut0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778276827; c=relaxed/simple; bh=fEmMe0Q34kTPBHLIu208stdayo1a6GHo8vxlUsm5ceE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=H6nQ6tChoKulXnStatQqUZZIRJjWADJCYMNdAmSLfQPV4rc1I99Fhe3XfBHja1RuzUM9A4S8IOnh3tfYPJzNgkQOyfx9ap5Ia7sgZgKjyssejRgkxARH2MZFvNQpTe369cpkpezzdl/TKQ8Aq64esXxtq7N9lt2B8YJoGeu7F6w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bl1A/JRu; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bl1A/JRu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 658AFC2BCB0; Fri, 8 May 2026 21:47:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778276826; bh=fEmMe0Q34kTPBHLIu208stdayo1a6GHo8vxlUsm5ceE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bl1A/JRuWLW/BQzfUkRIqZrKatEjwAQxtY627K2zimBOY0j8Xw81vH/o5uhdvOdsb NqG/jJq+Y/MGBeAsF3sCf3hvAvFnKInsQa3s2CXVmIZVlP+X6qW7eQhfiS2q3XrEeu NEqMsLj2j1Kouztefxl0VzT3ojDocvCeYu1qaFifVW6hjBxLdvu7zrELyuz9UGMGUp E8x/IY8Y5ohwOQSMiBXCAsRrD/2Cy90iv3FgcXL5uuixgJkXfqaVbSXP4e1E4obsRi 02Qxms5rOqjzvhFHHzB5JzcLL92Twhh8UipGavwbBTCtEJ9ElPfjNsZE3jl+aWQLnr n6abbKcW/j2cw== Date: Fri, 8 May 2026 17:47:04 -0400 From: Sasha Levin To: Andrew Morton Cc: corbet@lwn.net, skhan@linuxfoundation.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, gregkh@linuxfoundation.org Subject: Re: [PATCH] killswitch: add per-function short-circuit mitigation primitive Message-ID: References: <20260507070547.2268452-1-sashal@kernel.org> <20260508135630.a380e3c187b59e4c04e6f358@linux-foundation.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20260508135630.a380e3c187b59e4c04e6f358@linux-foundation.org> On Fri, May 08, 2026 at 01:56:30PM -0700, Andrew Morton wrote: >On Thu, 7 May 2026 03:05:45 -0400 Sasha Levin wrote: > >> When a (security) issue goes public, fleets stay exposed until a patched kernel >> is built, distributed, and rebooted into. >> >> For many such issues the simplest mitigation is to stop calling the buggy >> function. Killswitch provides that. An admin writes: >> >> echo "engage af_alg_sendmsg -1" \ >> > /sys/kernel/security/killswitch/control > >It certainly sounds useful, but what would I know. How do we hunt down >suitable operations people (aka "target audience") to find out how >useful this is to them? I'm not entierly sure here... If folks have suggestions on folks to loop in, that'll be great! >> 19 files changed, 1451 insertions(+), 1 deletion(-) > >wowzers. I'm looking at samples/livepatch/livepatch-sample.c wondering >"why"? Yup, a bit chunky, but over half of it is documentation and testing, and the actual functional code is largely the securityfs interface. -- Thanks, Sasha