From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 D305B7D3F4 for ; Tue, 5 Nov 2024 15:41:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730821275; cv=none; b=KoH7TxSDI4mVjnUsD2Ql2KtWIg6mBWtbzH3CZTISySkUGh6vRsldWEhLWfiP7gso8JmaV0HTXqQgK+AYYWOpUlL8OhxN7KhByVRHoFFyLMmP5sv+h1pyuyHisH0DF0bnRLcYeGPpgtBEyp0Pz+Ou9r5+UdtzSKcHZZWbvjtT2uQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730821275; c=relaxed/simple; bh=X8Tn2kfEz/8sQ8qe6hl0sZCPND4hV+hzMBpsCFo6Lgo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=s+wXGhnqsu+oZ/YXDKzTPKiY0HUR07VGOsuBnKZXTo3+UwQOskd7ThSMYFXCBYu3i6+boD9ibbyk/k4OXhxKkZZLDmos3cGvHUuroVrw0yz/4ZZsbGlXcLuBZPsC9TRswRr1D45duTfwMK87DLG41F9qq2HT1jBK8ewLQnx+HK4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=REuFJmXL; arc=none smtp.client-ip=198.137.202.133 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=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="REuFJmXL" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; 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=UPHw2IiDaWM/l4GsTAEfiswduoyNvvNd/EA3DH7veLY=; b=REuFJmXLaI3NKZGwq5OEvAl7i9 /PID4INtijbyyGTEaEyHIdtyl25s8Ljb7QOj6YUmKeqaCTCrbYImnMGt/btruBs6ACrTTzvXRlhKr nplynN2h7BDOUGcnGZdgv+D/gx4tXMyf/no0VRs+1yXVYE4aqgLZNNl1EpZnoNQtrKh1cv+biD1Fk mhKXcgwkhXsdGp7sJ4IjlontecOqgzXcm4tFJT8zu4LCPMLUlA+lLO1RdHDfI6hOjf8PwbNx7tIWb R4p329LF5N3J44GbwktzJMV6Jl0f5hfNsa7P7sQvgBJIOPLPU7PkW7Ih7K12tqx9gGCYlPS5+czkb ymWIALkg==; Received: from hch by bombadil.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1t8Lg9-0000000HSOs-1XAv; Tue, 05 Nov 2024 15:41:13 +0000 Date: Tue, 5 Nov 2024 07:41:13 -0800 From: Christoph Hellwig To: Peter Zijlstra Cc: Christoph Hellwig , x86@kernel.org, linux-kernel@vger.kernel.org, alyssa.milburn@intel.com, scott.d.constable@intel.com, joao@overdrivepizza.com, andrew.cooper3@citrix.com, jpoimboe@kernel.org, alexei.starovoitov@gmail.com, ebiggers@kernel.org, samitolvanen@google.com, kees@kernel.org Subject: Re: [PATCH 1/8] x86,kcfi: Fix EXPORT_SYMBOL vs kCFI Message-ID: References: <20241105113901.348320374@infradead.org> <20241105114521.852053765@infradead.org> <20241105142720.GG10375@noisy.programming.kicks-ass.net> <20241105145842.GH10375@noisy.programming.kicks-ass.net> 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: <20241105145842.GH10375@noisy.programming.kicks-ass.net> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Tue, Nov 05, 2024 at 03:58:42PM +0100, Peter Zijlstra wrote: > > bounded number of functions that are used as either default methods > > or as ready made callbacks. Everything else has no business being > > called indirectly. While disallowing this might be a bit of work, > > I think it would be a great security improvement. > > Well, we don't disagree. But since most of the EXPORT'ed functions are > done in C, we need something that works there too. Yes, absolutely. In fact I doubt there are more than a handful of assembly exports that are valid targets for indirect calls.