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=-14.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 B5C7AC33CAA for ; Mon, 20 Jan 2020 16:39:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 828C42073D for ; Mon, 20 Jan 2020 16:39:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="tMSVAicR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729285AbgATQjw (ORCPT ); Mon, 20 Jan 2020 11:39:52 -0500 Received: from mail-qt1-f193.google.com ([209.85.160.193]:42005 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729080AbgATQjw (ORCPT ); Mon, 20 Jan 2020 11:39:52 -0500 Received: by mail-qt1-f193.google.com with SMTP id j5so227847qtq.9 for ; Mon, 20 Jan 2020 08:39:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=sZcsttqoOqoppbG6e/pqRXCvsc9U04ANxonvw6+R+xA=; b=tMSVAicRbicpyLXDMO4rYsQeKh3JeBuTMmH7INzePJGBSTEWRijFlmLaEkpBkE/S0/ pPZ9Eqs4i4wySskXaxwgqiQ+9HdlDXQnB+4UkY3WxOmryFKLHp5o3MN7r4jddjcftDpl qvV5jFTHJ8gFeE0b+4taMTnl6tSGniO9r0muDyy7osmytx0zBVJP2jQWz5vH+sIbeuiP wHAfN+vnfGbWnq6EfmIgO42Aaq4jNmX7q+JIGmkH68GLnk7Gl9JHnMzIlkYAtLt3ChFm WqhEQXtyD/4BhCT0YDEBWq96VQmK4fl27mQF0j6ySeBFBPmbWzRhzAU2GzrmBiUAN4Im DxKg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=sZcsttqoOqoppbG6e/pqRXCvsc9U04ANxonvw6+R+xA=; b=XKzij/xL9hSWYzFf6OmiJrISJBpMeVdeihthqldc4/FC7D13OI3hyhVd86rnOigcnL XHrMf00H1gfWUKoabXlNPnaO7Y/lbaJ4adwHWiqO9RMHiIR76Dgf53tcU83+kOBOsWrF u/cjDhvV62XPLiiveqP3+D7/lNM6iLtzL6zUBhMPvN3WWMG90dXOVO58cc9oXT5fyxy9 CjN3EhgUVVRiFagISw/wBvVI95vLB3+mKpaAwklJeVSms428lVUmMdcgBZ32bPp9HbYM zlUfHYciEJdfMRnVKWet3wSbKCd/2Cf9CM3aI1lIo5VvqvK+CSSR8ipxE3vJWfmvqQj1 /4PQ== X-Gm-Message-State: APjAAAUzHFMIMUlSrQ09Ce/MApPKCj9XcogXmjJpnSM5yYZ6DJLrzO9M 8P427NOVR6E0ugAyTZCVDEsT818YAofHLw4un4tyFg== X-Google-Smtp-Source: APXvYqzrYE50D8YKSrDPkL1mTaP9NxaA9IUrSzhA5houBQEElh77ireRGTeCqawKKA+jbFPqIc+JLCDWas3HZC0qEcA= X-Received: by 2002:aed:3b6e:: with SMTP id q43mr129761qte.57.1579538390395; Mon, 20 Jan 2020 08:39:50 -0800 (PST) MIME-Version: 1.0 References: <20200120141927.114373-1-elver@google.com> In-Reply-To: From: Dmitry Vyukov Date: Mon, 20 Jan 2020 17:39:39 +0100 Message-ID: Subject: Re: [PATCH 1/5] include/linux: Add instrumented.h infrastructure To: Marco Elver Cc: "Paul E. McKenney" , Andrey Konovalov , Alexander Potapenko , kasan-dev , LKML , Mark Rutland , Will Deacon , Peter Zijlstra , Boqun Feng , Arnd Bergmann , Al Viro , Christophe Leroy , Daniel Axtens , Michael Ellerman , Steven Rostedt , Masami Hiramatsu , Ingo Molnar , Christian Brauner , Daniel Borkmann , cyphar@cyphar.com, Kees Cook , linux-arch Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 20, 2020 at 5:25 PM Marco Elver wrote: > > > > > > > This adds instrumented.h, which provides generic wrappers for memory > > > > > > > access instrumentation that the compiler cannot emit for various > > > > > > > sanitizers. Currently this unifies KASAN and KCSAN instrumentation. In > > > > > > > future this will also include KMSAN instrumentation. > > > > > > > > > > > > > > Note that, copy_{to,from}_user require special instrumentation, > > > > > > > providing hooks before and after the access, since we may need to know > > > > > > > the actual bytes accessed (currently this is relevant for KCSAN, and is > > > > > > > also relevant in future for KMSAN). > > > > > > > > > > > > > > Suggested-by: Arnd Bergmann > > > > > > > Signed-off-by: Marco Elver > > > > > > > --- > > > > > > > include/linux/instrumented.h | 153 +++++++++++++++++++++++++++++++++++ > > > > > > > 1 file changed, 153 insertions(+) > > > > > > > create mode 100644 include/linux/instrumented.h > > > > > > > > > > > > > > diff --git a/include/linux/instrumented.h b/include/linux/instrumented.h > > > > > > > new file mode 100644 > > > > > > > index 000000000000..9f83c8520223 > > > > > > > --- /dev/null > > > > > > > +++ b/include/linux/instrumented.h > > > > > > > @@ -0,0 +1,153 @@ > > > > > > > +/* SPDX-License-Identifier: GPL-2.0 */ > > > > > > > + > > > > > > > +/* > > > > > > > + * This header provides generic wrappers for memory access instrumentation that > > > > > > > + * the compiler cannot emit for: KASAN, KCSAN. > > > > > > > + */ > > > > > > > +#ifndef _LINUX_INSTRUMENTED_H > > > > > > > +#define _LINUX_INSTRUMENTED_H > > > > > > > + > > > > > > > +#include > > > > > > > +#include > > > > > > > +#include > > > > > > > +#include > > > > > > > + > > > > > > > +/** > > > > > > > + * instrument_read - instrument regular read access > > > > > > > + * > > > > > > > + * Instrument a regular read access. The instrumentation should be inserted > > > > > > > + * before the actual read happens. > > > > > > > + * > > > > > > > + * @ptr address of access > > > > > > > + * @size size of access > > > > > > > + */ > > > > > > > > > > > > Based on offline discussion, that's what we add for KMSAN: > > > > > > > > > > > > > +static __always_inline void instrument_read(const volatile void *v, size_t size) > > > > > > > +{ > > > > > > > + kasan_check_read(v, size); > > > > > > > + kcsan_check_read(v, size); > > > > > > > > > > > > KMSAN: nothing > > > > > > > > > > KMSAN also has instrumentation in > > > > > copy_to_user_page/copy_from_user_page. Do we need to do anything for > > > > > KASAN/KCSAN for these functions? > > > > > > copy_to_user_page/copy_from_user_page can be instrumented with > > > instrument_copy_{to,from}_user_. I prefer keeping this series with no > > > functional change intended for KASAN at least. > > > > > > > There is also copy_user_highpage. > > > > > > > > And ioread/write8/16/32_rep: do we need any instrumentation there. It > > > > seems we want both KSAN and KCSAN too. One may argue that KCSAN > > > > instrumentation there is to super critical at this point, but KASAN > > > > instrumentation is important, if anything to prevent silent memory > > > > corruptions. How do we instrument there? I don't see how it maps to > > > > any of the existing instrumentation functions. > > > > > > These should be able to use the regular instrument_{read,write}. I > > > prefer keeping this series with no functional change intended for > > > KASAN at least. > > > > instrument_{read,write} will not contain any KMSAN instrumentation, > > which means we will effectively remove KMSAN instrumentation, which is > > weird because we instrumented these functions because of KMSAN in the > > first place... > > > > > > There is also kmsan_check_skb/kmsan_handle_dma/kmsan_handle_urb that > > > > does not seem to map to any of the instrumentation functions. > > > > > > For now, I would rather that there are some one-off special > > > instrumentation, like for KMSAN. Coming up with a unified interface > > > here that, without the use-cases even settled, seems hard to justify. > > > Once instrumentation for these have settled, unifying the interface > > > would have better justification. > > > > I would assume they may also require an annotation that checks the > > memory region under all 3 tools and we don't have such annotation > > (same as the previous case and effectively copy_to_user). I would > > expect such annotation will be used in more places once we start > > looking for more opportunities. > > Agreed, I'm certainly not against adding these. We may need to > introduce 'instrument_dma_' etc. However, would it be reasonable to do > this in a separate follow-up patch-series, to avoid stalling bitops > instrumentation? Assuming that the 8 hooks in instrumented.h right > now are reasonable, and such future changes add new hooks, I think > that would be the more pragmatic approach. I think it would be a wrong direction. Just like this change does not introduce all of instrument_test_and_set_bit, instrument___clear_bit_unlock, instrument_copyin, instrument_copyout_mcsafe, instrument_atomic_andnot, .... All of these can be grouped into a very small set of cases with respect to what type of memory access they do from the point of view of sanitizers. And we introduce instrumentation for these _types_ of accesses, rather than application functions (we don't care much if the access is for atomic operations, copy to/from user, usb, dma, skb or something else). It seems that our set of instrumentation annotations can't handle some very basic cases...