From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 2140B24166C; Fri, 14 Feb 2025 10:05:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739527550; cv=none; b=AIhrY7dqal/9A6qjiL3cCFRgzmXSpc5dD+94PcxtAcol72GBYyRkjPSD0wU2U7Prflm5mbGkgW6iMxUfcRdHnUfwCwhlNe+ar7QvdvtEAXfKF1qmLLFEfbmj+PFs1NQbkOKQd7K8ZlSp8G3TpZKsIDb0vOyO6Y5iChECv73sxFg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739527550; c=relaxed/simple; bh=hEXV7yfCSHFzsOP4HMvf4zh9MsM4ube2N74I3JPqssE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=tJT66GvdgAlpIpajINnqc5t4JGwudn+r6CvXakQ5FcjIitbpLNoD3F7msLRi9PIqZ2DIA+jNFsQv7YJ4BVE62tmX3cYwf20CAXP1dvephBguix9ZANUwU+qnZ9+9JQcPpyEMerPO5n1sZkQA0YM4IuO0TIF9qQ5UHbMAOJ5aqZU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=nMGjjVI1; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="nMGjjVI1" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=hEXV7yfCSHFzsOP4HMvf4zh9MsM4ube2N74I3JPqssE=; b=nMGjjVI1H2TwZJKNmdf35JE8Vv 000AmU9Jaq0zGxW6lDXMT/kvftMXTdEihJNgYiFiS43HDy1HpyHZU8FM4zT+9psLF/6KAIOw94dlX zzV+R+bxi3NkNjHgQh7NtmL6ea1TxSONeZQs5fMZw/V+SF1wfJnj4scOiHmpCfb+vKVq3Lx4zzJgS RqSlZq8F7NnSNWN3UtV1ZgNBLgT3lpf9QYZJBFH2PAMAYpYGVrk1s7R/YZ+UZAZTMuOIZ9VnrzqpU vD7sMfLBjprEHtOyUq80imHQvoGX8co9DYpDgXgsE9mEhfBbX7hr23e0PRsRIRCkcX0CvNVPgtM1I 8a8L9CLA==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tisZu-0000000AwUc-1RaT; Fri, 14 Feb 2025 10:05:46 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id E77E830050D; Fri, 14 Feb 2025 11:05:45 +0100 (CET) Date: Fri, 14 Feb 2025 11:05:45 +0100 From: Peter Zijlstra To: Andrew Cooper Cc: Kees Cook , jannh@google.com, jmill@asu.edu, joao@overdrivepizza.com, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, luto@kernel.org, samitolvanen@google.com Subject: Re: [RFC] Circumventing FineIBT Via Entrypoints Message-ID: <20250214100545.GG21726@noisy.programming.kicks-ass.net> References: <202502131224.D6F5A235@keescook> <6641d1e0-7151-4857-bb0e-db555d4cdf50@citrix.com> 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 Content-Disposition: inline In-Reply-To: <6641d1e0-7151-4857-bb0e-db555d4cdf50@citrix.com> On Thu, Feb 13, 2025 at 08:41:16PM +0000, Andrew Cooper wrote: > The problem is that SYSCALL entry/exit is a toxic operating mode, > because you only have to think about sneezing and another user->kernel > priv-esc appears. For a very brief moment I thought we could leave out the ENDBR there and eat the #CP, but 1) slow, and 2) then #CP needs to be an IST and ARGHH. So yeah, I didn't just suggest anything at all. I hate all this.