From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mslow1.mail.gandi.net (mslow1.mail.gandi.net [217.70.178.240]) (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 5F0E72F21 for ; Wed, 9 Feb 2022 05:26:41 +0000 (UTC) Received: from relay5-d.mail.gandi.net (unknown [IPv6:2001:4b98:dc4:8::225]) by mslow1.mail.gandi.net (Postfix) with ESMTP id 5AC8FC7ACE for ; Wed, 9 Feb 2022 05:18:54 +0000 (UTC) Received: (Authenticated sender: joao@overdrivepizza.com) by mail.gandi.net (Postfix) with ESMTPA id 5123B1C0002; Wed, 9 Feb 2022 05:18:44 +0000 (UTC) Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Tue, 08 Feb 2022 21:18:44 -0800 From: Joao Moreira To: Kees Cook Cc: Peter Zijlstra , x86@kernel.org, hjl.tools@gmail.com, jpoimboe@redhat.com, andrew.cooper3@citrix.com, linux-kernel@vger.kernel.org, ndesaulniers@google.com, samitolvanen@google.com, llvm@lists.linux.dev Subject: Re: [RFC][PATCH 6/6] objtool: Add IBT validation / fixups In-Reply-To: <202202082003.FA77867@keescook> References: <20211122170301.764232470@infradead.org> <20211122170805.338489412@infradead.org> <6ebb0ab131c522f20c094294d49091fc@overdrivepizza.com> <202202081541.900F9E1B@keescook> <202202082003.FA77867@keescook> Message-ID: <9ea50c51ee8db366430c9dc697a83923@overdrivepizza.com> X-Sender: joao@overdrivepizza.com Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit > Ah, excellent, thanks for the pointers. There's also this in the works: > https://reviews.llvm.org/D119296 (a new CFI mode, designed to play nice > to objtool, IBT, etc.) Oh, great! Thanks for pointing it out. I guess I saw something with a similar name before ;) https://www.blackhat.com/docs/asia-17/materials/asia-17-Moreira-Drop-The-Rop-Fine-Grained-Control-Flow-Integrity-For-The-Linux-Kernel.pdf Jokes aside (and perhaps questions more targeted to Sami), from a diagonal look it seems that this follows the good old tag approach proposed by PaX/grsecurity, right? If this is the case, should I assume it could also benefit from features like -mibt-seal? Also are you considering that perhaps we can use alternatives to flip different CFI instrumentation as suggested by PeterZ in another thread? Tks, Joao