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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 2D66CC433DF for ; Sat, 15 Aug 2020 21:54:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0EF182053B for ; Sat, 15 Aug 2020 21:54:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="bp6qJV4D" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729304AbgHOVyo (ORCPT ); Sat, 15 Aug 2020 17:54:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45612 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729108AbgHOVwd (ORCPT ); Sat, 15 Aug 2020 17:52:33 -0400 Received: from mail-pl1-x641.google.com (mail-pl1-x641.google.com [IPv6:2607:f8b0:4864:20::641]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 51CA8C0A88B5 for ; Sat, 15 Aug 2020 09:59:59 -0700 (PDT) Received: by mail-pl1-x641.google.com with SMTP id k13so5492846plk.13 for ; Sat, 15 Aug 2020 09:59:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=Rb/IMQYAMEFrYCtyEvFVd8k7Hv2cYtIwx71PE3QM1p8=; b=bp6qJV4DEhzLrf629/G+tL9EvTZVqc/ysLjd/vQMHp+0jiX1XZtLIgjqec6Lpt/AaN WTq7cZUtJPMxGLrYA4iDCx3FAGjWmYa10boN5IBn8zvQ0LJy4jLy97V0yeOktIX46fym j+NDd7YOcqJgHy11LHoejm8VJES3NQHihXr5g= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=Rb/IMQYAMEFrYCtyEvFVd8k7Hv2cYtIwx71PE3QM1p8=; b=XaPp4wIO8GUzD3GSNyyZw8Pbv5vMvwXN4/c8E3tjCh/FAYLEmIdGOik1wZu2sWzIqQ ZhSynJXHCZujgRkm5isUjJ03ljWB9J3r9jKX3CRi0KeEmm2qyffx165ay15+xCkNVwRf Jzj19dnHXFpPwjQBQhx1Nm0FFRWJKEdb24ZmQ/rQerizmpBenzR7LKxUI2Acrve9nwTL GLSCDRABsVi3BZLavLWVPkIv6mNzwjhYLM29FnwUZzwH+AEzxDMMzfaEQIPtL5KRq4rd mhiiMpvtTJOdRVF7mAnltqmflLJ6ta+0yMG5v/XJOgs99lwEMbcIfVlPr1xcSXWXWWq9 HRPw== X-Gm-Message-State: AOAM531dVhVQGoqQIrYpMziAqedsgrOB4V7a4aeVdMJCHgSC/cb0rEhb Y3rSJpsYSToxHMr2eB9jwZQhJQ== X-Google-Smtp-Source: ABdhPJzCrWUNRjB+5ydtKJX7u7Wr14mIRwWEOzQPie8wMcCnFEFODVqD0y9uyzTzDe5hmkp2qfJd5A== X-Received: by 2002:a17:90a:e986:: with SMTP id v6mr6862878pjy.88.1597510798065; Sat, 15 Aug 2020 09:59:58 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id d127sm12507740pfc.175.2020.08.15.09.59.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 15 Aug 2020 09:59:57 -0700 (PDT) Date: Sat, 15 Aug 2020 09:59:56 -0700 From: Kees Cook To: Alexander Popov Cc: Jann Horn , Will Deacon , Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Masahiro Yamada , Masami Hiramatsu , Steven Rostedt , Peter Zijlstra , Krzysztof Kozlowski , Patrick Bellasi , David Howells , Eric Biederman , Johannes Weiner , Laura Abbott , Arnd Bergmann , Greg Kroah-Hartman , kasan-dev@googlegroups.com, linux-mm@kvack.org, kernel-hardening@lists.openwall.com, linux-kernel@vger.kernel.org, notify@kernel.org Subject: Re: [PATCH RFC 2/2] lkdtm: Add heap spraying test Message-ID: <202008150952.E81C4A52F@keescook> References: <20200813151922.1093791-1-alex.popov@linux.com> <20200813151922.1093791-3-alex.popov@linux.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200813151922.1093791-3-alex.popov@linux.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 13, 2020 at 06:19:22PM +0300, Alexander Popov wrote: > Add a simple test for CONFIG_SLAB_QUARANTINE. > > It performs heap spraying that aims to reallocate the recently freed heap > object. This technique is used for exploiting use-after-free > vulnerabilities in the kernel code. > > This test shows that CONFIG_SLAB_QUARANTINE breaks heap spraying > exploitation technique. Yay tests! > > Signed-off-by: Alexander Popov > --- > drivers/misc/lkdtm/core.c | 1 + > drivers/misc/lkdtm/heap.c | 40 ++++++++++++++++++++++++++++++++++++++ > drivers/misc/lkdtm/lkdtm.h | 1 + > 3 files changed, 42 insertions(+) > > diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c > index a5e344df9166..78b7669c35eb 100644 > --- a/drivers/misc/lkdtm/core.c > +++ b/drivers/misc/lkdtm/core.c > @@ -126,6 +126,7 @@ static const struct crashtype crashtypes[] = { > CRASHTYPE(SLAB_FREE_DOUBLE), > CRASHTYPE(SLAB_FREE_CROSS), > CRASHTYPE(SLAB_FREE_PAGE), > + CRASHTYPE(HEAP_SPRAY), > CRASHTYPE(SOFTLOCKUP), > CRASHTYPE(HARDLOCKUP), > CRASHTYPE(SPINLOCKUP), > diff --git a/drivers/misc/lkdtm/heap.c b/drivers/misc/lkdtm/heap.c > index 1323bc16f113..a72a241e314a 100644 > --- a/drivers/misc/lkdtm/heap.c > +++ b/drivers/misc/lkdtm/heap.c > @@ -205,6 +205,46 @@ static void ctor_a(void *region) > static void ctor_b(void *region) > { } > > +#define HEAP_SPRAY_SIZE 128 > + > +void lkdtm_HEAP_SPRAY(void) > +{ > + int *addr; > + int *spray_addrs[HEAP_SPRAY_SIZE] = { 0 }; (the 0 isn't needed -- and it was left there, it should be NULL) > + unsigned long i = 0; > + > + addr = kmem_cache_alloc(a_cache, GFP_KERNEL); I would prefer this test add its own cache (e.g. spray_cache), to avoid misbehaviors between tests. (e.g. the a and b caches already run the risk of getting corrupted weirdly.) > + if (!addr) { > + pr_info("Unable to allocate memory in lkdtm-heap-a cache\n"); > + return; > + } > + > + *addr = 0x31337; > + kmem_cache_free(a_cache, addr); > + > + pr_info("Performing heap spraying...\n"); > + for (i = 0; i < HEAP_SPRAY_SIZE; i++) { > + spray_addrs[i] = kmem_cache_alloc(a_cache, GFP_KERNEL); > + *spray_addrs[i] = 0x31337; > + pr_info("attempt %lu: spray alloc addr %p vs freed addr %p\n", > + i, spray_addrs[i], addr); That's 128 lines spewed into dmesg... I would leave this out. > + if (spray_addrs[i] == addr) { > + pr_info("freed addr is reallocated!\n"); > + break; > + } > + } > + > + if (i < HEAP_SPRAY_SIZE) > + pr_info("FAIL! Heap spraying succeed :(\n"); I'd move this into the "if (spray_addrs[i] == addr)" test instead of the pr_info() that is there. > + else > + pr_info("OK! Heap spraying hasn't succeed :)\n"); And then make this an "if (i == HEAP_SPRAY_SIZE)" test > + > + for (i = 0; i < HEAP_SPRAY_SIZE; i++) { > + if (spray_addrs[i]) > + kmem_cache_free(a_cache, spray_addrs[i]); > + } > +} > + > void __init lkdtm_heap_init(void) > { > double_free_cache = kmem_cache_create("lkdtm-heap-double_free", > diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h > index 8878538b2c13..dfafb4ae6f3a 100644 > --- a/drivers/misc/lkdtm/lkdtm.h > +++ b/drivers/misc/lkdtm/lkdtm.h > @@ -45,6 +45,7 @@ void lkdtm_READ_BUDDY_AFTER_FREE(void); > void lkdtm_SLAB_FREE_DOUBLE(void); > void lkdtm_SLAB_FREE_CROSS(void); > void lkdtm_SLAB_FREE_PAGE(void); > +void lkdtm_HEAP_SPRAY(void); > > /* lkdtm_perms.c */ > void __init lkdtm_perms_init(void); > -- > 2.26.2 > I assume enabling the quarantine defense also ends up being seen in the SLAB_FREE_DOUBLE LKDTM test too, yes? -- Kees Cook