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 D25FD2C0267 for ; Tue, 26 Aug 2025 12:34:47 +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=1756211689; cv=none; b=Kwy93bFRVSX1mvF2YPy7P/00Z83h1ibWm7xmNNP6OxbY/AVw/JSIZ5Z8Dr2qPtT2wcLt+KMcc3Bm+U8tfzCKL7BnlB+zSSHzND2KX9/usGAwJ5iwnLLVHA1OyDaYdjK8H5TC0SyuOf4m24JAgVNWQFjyAmIaNvXWsdhmHiYjjYM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756211689; c=relaxed/simple; bh=g+z3yZRdrZRLtObGahP3SKkF1sXUGzV9b4ohegycO9k=; h=Date:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To:From; b=Iuzx0CpEE5SQ1U+oE1hUjMaHaXYiYp7hYP852D0dsYpPJk+gDk9HT+y0t6dYbN4zTFnQWj8FJmmy64+9aH2eGcK+i+pv5avel1zQErl4cgLx7rsTFYxXPVh0bKZ7dWe8ZiSIxPnfAGcp6CInzVpGpTUma1Ni1WmpvnqxB1xARiQ= 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=b8GII4CJ; 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="b8GII4CJ" Received: from trampoline.thunk.org (pool-173-48-119-77.bstnma.fios.verizon.net [173.48.119.77]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 57QCUf2V005662 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 26 Aug 2025 08:30:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mit.edu; s=outgoing; t=1756211450; bh=gfBKabosxEFtok1jhLkwvxbr40tlm8siH8D4p2Cx5vc=; h=Date:Subject:Message-ID:MIME-Version:Content-Type:From; b=b8GII4CJJPfrDPxvB9Xkdi0sqO33xqyhjhyC9qdBJqJW/dCH804qFrwyFAxn2OZBY Hx/Gz6dSA7W9aVjxxpye9lOfRVq+7gssepbPckc+6tJjKM5KeOZQzwY+wTIqX10xlT zPaBEdKd/kyFu0yacX3gXr8Gitguh87mEfx6yREqi0uWNtZGKzQMYh0JQvKO0hhDTi vSyM573nYo5yqDMnBnY8yy6iD+vznX9EIEcSlWJZcS91rCIV6aSvMj0QmEAvxhPg7b qtKT3t8q4RGh99UggPBiE028v3jpn+rrQCTJPH9tGBzx+zJqqJpXlHQg1DdLH2fI+D IG3e2BChNa9AQ== Received: by trampoline.thunk.org (Postfix, from userid 15806) id 73FBB2E00D6; Tue, 26 Aug 2025 08:30:41 -0400 (EDT) Date: Tue, 26 Aug 2025 08:30:41 -0400 To: =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= Cc: Christian Brauner , Al Viro , Kees Cook , Paul Moore , Serge Hallyn , Andy Lutomirski , Arnd Bergmann , Christian Heimes , Dmitry Vyukov , Elliott Hughes , Fan Wu , Florian Weimer , Jann Horn , Jeff Xu , Jonathan Corbet , Jordan R Abrahams , Lakshmi Ramasubramanian , Luca Boccassi , Matt Bobrowski , Miklos Szeredi , Mimi Zohar , Nicolas Bouchinet , Robert Waite , Roberto Sassu , Scott Shell , Steve Dower , Steve Grubb , kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: Re: [RFC PATCH v1 0/2] Add O_DENY_WRITE (complement AT_EXECVE_CHECK) Message-ID: <20250826123041.GB1603531@mit.edu> References: <20250822170800.2116980-1-mic@digikod.net> <20250826-skorpion-magma-141496988fdc@brauner> <20250826.aig5aiShunga@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=us-ascii Content-Disposition: inline In-Reply-To: <20250826.aig5aiShunga@digikod.net> bFrom: Theodore Ts'o From: "Theodore Ts'o" Is there a single, unified design and requirements document that describes the threat model, and what you are trying to achieve with AT_EXECVE_CHECK and O_DENY_WRITE? I've been looking at the cover letters for AT_EXECVE_CHECK and O_DENY_WRITE, and the documentation that has landed for AT_EXECVE_CHECK and it really doesn't describe what *are* the checks that AT_EXECVE_CHECK is trying to achieve: "The AT_EXECVE_CHECK execveat(2) flag, and the SECBIT_EXEC_RESTRICT_FILE and SECBIT_EXEC_DENY_INTERACTIVE securebits are intended for script interpreters and dynamic linkers to enforce a consistent execution security policy handled by the kernel." Um, what security policy? What checks? What is a sample exploit which is blocked by AT_EXECVE_CHECK? And then on top of it, why can't you do these checks by modifying the script interpreters? Confused, - Ted