From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) (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 009D03271E0 for ; Wed, 18 Feb 2026 13:30:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=18.9.28.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771421432; cv=none; b=WXLjw+4YD0XHenyW8qTtRkwv3L9jKZc/cuPmyE6N+6jhSbUHPpK4231feb/4SbjBdXfvUyJP25Vxd8Fc+P0UW80SVuLXeLoayKDiTgPeflmCddQA9e84pLLi6vOrtm1d3bTB//kNL84gAteyl5dTAII/jQp1kgXVxqMzwtHsKgY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771421432; c=relaxed/simple; bh=BUcbqGXHuR1KNA7AOVUKexsQGN8FVHG6OgIdvHbwxhA=; h=Date:From:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=I5uNenomDnua72JKh+FtFKjphiC+xbvJ/O0kZAf7DflHs4CgaVmGaFYy/xNDcicFKQ+lmi8EPzf4OK7SxNEsLvtv72JP/94EDJy8Re+R5VYhIyeR1z0Ybcc0ZqGVBBtamzLTkgXnCwhFIxMSkZRon/tTPuNyICE5Jh4pFsd+aqI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=mit.edu; spf=pass smtp.mailfrom=mit.edu; dkim=pass (2048-bit key) header.d=mit.edu header.i=@mit.edu header.b=NXAsZZ6d; arc=none smtp.client-ip=18.9.28.11 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=mit.edu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mit.edu Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mit.edu header.i=@mit.edu header.b="NXAsZZ6d" Received: from macsyma.thunk.org (pool-173-48-113-47.bstnma.fios.verizon.net [173.48.113.47]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 61IDTtYH018341 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 18 Feb 2026 08:29:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mit.edu; s=outgoing; t=1771421397; bh=ttRrWrhPrzLzmBLq8cse1fRC/Cd5ZBOuRs3LOAaPw2g=; h=Date:From:Subject:Message-ID:MIME-Version:Content-Type; b=NXAsZZ6dfomZQDhQDoXUYVVnsdoELU1CMDZkwfnRjcDsXbYipDX9bUREA/wiAhhMw UO8G3+ipWoUbqG9v7pz9RwNVOXmUYTIKGlzLxcNnJfjLHKEsnlCIjMxjroY5W+0Ual jzrDv7Gkqc83fMCglCLkDerIiLxaAir0a+1AQo2cRVMkebTR48nTuUniaqGj6vgXIG YP88DgunCIw/z3B4nXCwyjOVmsq4byEd/tAEiorBiSQl7AdModYKnnNmN6UcppC8X6 xrVVCqf1y7R/wCs08VKsz6lNE4xhgnJBeoteMrm5t86MDluBjZ9CovO/eDZkPxbN3/ LP+0K9CBPef1g== Received: by macsyma.thunk.org (Postfix, from userid 15806) id 1A8CA58FE818; Wed, 18 Feb 2026 08:29:55 -0500 (EST) Date: Wed, 18 Feb 2026 08:29:54 -0500 From: "Theodore Tso" Cc: Jann Horn , Christian Brauner , Oleg Nesterov , Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH RFC v3 2/4] pidfd: add CLONE_PIDFD_AUTOKILL Message-ID: <20260218132954.GA45984@macsyma-wired.lan> References: <20260217-work-pidfs-autoreap-v3-0-33a403c20111@kernel.org> <20260217-work-pidfs-autoreap-v3-2-33a403c20111@kernel.org> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Feb 17, 2026 at 03:44:52PM -0800, Linus Torvalds wrote: > On Tue, 17 Feb 2026 at 15:38, Jann Horn wrote: > > > > You can already send SIGHUP to such binaries through things like job > > control, right? > > But at least those can be blocked, and people can disassociate > themselves from a tty if they care etc. Does CLONE_PIDFD_AUTOKILL need to send a SIGKILL? Could it be something that could be trapped/blocked, like SIGHUP or SIGTERM? Or maybe we could do the SIGHUP, wait 30 seconds (+/- a random delay), if it hasn't exited, send SIGTERM, wait another 30 seconds (+/- a random delay) if it hasn't exited send a SIGKILL. That's still a change in the security model, but it's less likely to cause problems if the goal is to try to catch a setuid program while it is in the middle of editing some critical file such as /etc/sudo.conf or /etc/passwd or some such. I bet we'll still see some zero days coming out of this, but we can at least mitigate likelihood of security breach. - Ted