From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 52C37C433F5 for ; Wed, 5 Sep 2018 08:00:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F2D4C2073D for ; Wed, 5 Sep 2018 08:00:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="dlO6izT4" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F2D4C2073D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727763AbeIEM3d (ORCPT ); Wed, 5 Sep 2018 08:29:33 -0400 Received: from merlin.infradead.org ([205.233.59.134]:58004 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725865AbeIEM3d (ORCPT ); Wed, 5 Sep 2018 08:29:33 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=Bccg/sqRmHoYryjYvfS8XDjyIJWrKKmY7wopmwauC3M=; b=dlO6izT4Gi+2NiVHVie8fGGP2 fUxqSV/qj9zDBP9UJHwu5bHjPRJkruvFWfX0xleb9uAJAjEj2G5mz8MwUQeXBM3vAgsGNu6CIJPCU VPV/0NnRyKsiaQS5ba/f4IbjVkHrAj74CTQ+D02SX6XUIGcD5wp+6QlphYmtHNGOfjhitn/b+ahVA d5474rJT6xA4cJU/PhM3VJpWG8TVfKAUVwOiiHD8C0VUwNnAwp2UNHUAI+cq6kYBiU9moFHUGGk7x coyyQT1dw7oADON3XCUToyOURk6BMt5trGXK00PiMxk+S2TCz1A1b2v1YLWvzkKMH5zqN2GIPkLM2 Rcpv7oqYQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fxSji-0003ky-0t; Wed, 05 Sep 2018 08:00:26 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id D8D4C20191BFF; Wed, 5 Sep 2018 10:00:24 +0200 (CEST) Date: Wed, 5 Sep 2018 10:00:24 +0200 From: Peter Zijlstra To: Jiri Kosina Cc: Tim Chen , Thomas Gleixner , Ingo Molnar , Josh Poimboeuf , Andrea Arcangeli , "Woodhouse, David" , Oleg Nesterov , Casey Schaufler , linux-kernel@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH v3 1/3] ptrace: Provide ___ptrace_may_access() that can be applied on arbitrary tasks Message-ID: <20180905080024.GP24124@hirez.programming.kicks-ass.net> References: <31436186-88da-324e-88a0-8fdca7bf60ac@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 04, 2018 at 07:35:29PM +0200, Jiri Kosina wrote: > On Tue, 4 Sep 2018, Tim Chen wrote: > > > > Current ptrace_may_access() implementation assumes that the 'source' task is > > > always the caller (current). > > > > > > Expose ___ptrace_may_access() that can be used to apply the check on arbitrary > > > tasks. > > > > Casey recently has proposed putting the decision making of whether to > > do IBPB in the security module. > > > > https://lwn.net/ml/kernel-hardening/20180815235355.14908-4-casey.schaufler@intel.com/ > > > > That will have the advantage of giving the administrator a more flexibility > > of when to turn on IBPB. The policy is very similar to what you have proposed here > > but I think the security module is a more appropriate place for the security policy. > > Yeah, well, honestly, I have a bit hard time buying the "generic > sidechannel prevention security module" idea, given how completely > different in nature all the mitigations have been so far. I don't see that > trying to abstract this somehow provides more clarity. > > So if this should be done in LSM, it'd probably have to be written by > someone else than me :) who actually understands how the "sidechannel LSM" > idea works. Yeah, I'm not convinced on LSM either. Lets just do these here patches first and then Casey can try and convince us later.