From patchwork Mon Jul 25 19:16:24 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laura Abbott X-Patchwork-Id: 652390 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3ryrc3272jz9sdg for ; Tue, 26 Jul 2016 05:17:23 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753663AbcGYTRV (ORCPT ); Mon, 25 Jul 2016 15:17:21 -0400 Received: from mail-it0-f46.google.com ([209.85.214.46]:38463 "EHLO mail-it0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753239AbcGYTQb (ORCPT ); Mon, 25 Jul 2016 15:16:31 -0400 Received: by mail-it0-f46.google.com with SMTP id j124so115277196ith.1 for ; Mon, 25 Jul 2016 12:16:30 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:subject:to:references:cc:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding; bh=1alCQ/YBsVzJqQWPZrNwmdfhELVQ9bxw+LYCj445z2A=; b=g9gaWqVIhZLsxggaMB5AcVAHrvoNyf3YHaxttUKENhPfc8XPVBqGBWLUVw8n88POfT sf2W1H9qPfTBLq2Lh3V4Z2bjMea7GgSPEU+91h41gSRIZST+qK43LcOeDwGRh8AE1UbL laTzMqNkEMPMHD9ef7RbQoPNWkXzxHO6SPS6CMrm+u1n9D2ujUZnE7fnSz4rNv+mh/Yp Yrft8DLfXCa/ln/4x1vpSyEScH/uAhulMttUaAkVvC4zHdzTWHcenbwKCuc9I5tPEwGH Nx1aGmX37O24ZcUxZgk3u6cnEI2NhMfFv7sUsAaR/Sq5A1EVJkyYZeERz4I4mlhovdoy wa2A== X-Gm-Message-State: AEkooutrrAnsFXY9UDRLYd03GL/ir0856i/8PFA9iE17vlEteLFgL3m0qhzaZiLegUlpMDNx X-Received: by 10.36.208.71 with SMTP id m68mr22567397itg.63.1469474190133; Mon, 25 Jul 2016 12:16:30 -0700 (PDT) Received: from ?IPv6:2601:602:9800:177f::337f? ([2601:602:9800:177f::337f]) by smtp.gmail.com with ESMTPSA id z128sm12136642iof.4.2016.07.25.12.16.25 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 25 Jul 2016 12:16:28 -0700 (PDT) From: Laura Abbott Subject: Re: [PATCH v4 12/12] mm: SLUB hardened usercopy support To: Kees Cook , kernel-hardening@lists.openwall.com References: <1469046427-12696-1-git-send-email-keescook@chromium.org> <1469046427-12696-13-git-send-email-keescook@chromium.org> Cc: Laura Abbott , Balbir Singh , Daniel Micay , Josh Poimboeuf , Rik van Riel , Casey Schaufler , PaX Team , Brad Spengler , Russell King , Catalin Marinas , Will Deacon , Ard Biesheuvel , Benjamin Herrenschmidt , Michael Ellerman , Tony Luck , Fenghua Yu , "David S. Miller" , x86@kernel.org, Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Andy Lutomirski , Borislav Petkov , Mathias Krause , Jan Kara , Vitaly Wool , Andrea Arcangeli , Dmitry Vyukov , linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Message-ID: <0f980e84-b587-3d9e-3c26-ad57f947c08b@redhat.com> Date: Mon, 25 Jul 2016 12:16:24 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 MIME-Version: 1.0 In-Reply-To: <1469046427-12696-13-git-send-email-keescook@chromium.org> Sender: sparclinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: sparclinux@vger.kernel.org On 07/20/2016 01:27 PM, Kees Cook wrote: > Under CONFIG_HARDENED_USERCOPY, this adds object size checking to the > SLUB allocator to catch any copies that may span objects. Includes a > redzone handling fix discovered by Michael Ellerman. > > Based on code from PaX and grsecurity. > > Signed-off-by: Kees Cook > Tested-by: Michael Ellerman > --- > init/Kconfig | 1 + > mm/slub.c | 36 ++++++++++++++++++++++++++++++++++++ > 2 files changed, 37 insertions(+) > > diff --git a/init/Kconfig b/init/Kconfig > index 798c2020ee7c..1c4711819dfd 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -1765,6 +1765,7 @@ config SLAB > > config SLUB > bool "SLUB (Unqueued Allocator)" > + select HAVE_HARDENED_USERCOPY_ALLOCATOR > help > SLUB is a slab allocator that minimizes cache line usage > instead of managing queues of cached objects (SLAB approach). > diff --git a/mm/slub.c b/mm/slub.c > index 825ff4505336..7dee3d9a5843 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -3614,6 +3614,42 @@ void *__kmalloc_node(size_t size, gfp_t flags, int node) > EXPORT_SYMBOL(__kmalloc_node); > #endif > > +#ifdef CONFIG_HARDENED_USERCOPY > +/* > + * Rejects objects that are incorrectly sized. > + * > + * Returns NULL if check passes, otherwise const char * to name of cache > + * to indicate an error. > + */ > +const char *__check_heap_object(const void *ptr, unsigned long n, > + struct page *page) > +{ > + struct kmem_cache *s; > + unsigned long offset; > + size_t object_size; > + > + /* Find object and usable object size. */ > + s = page->slab_cache; > + object_size = slab_ksize(s); > + > + /* Find offset within object. */ > + offset = (ptr - page_address(page)) % s->size; > + > + /* Adjust for redzone and reject if within the redzone. */ > + if (kmem_cache_debug(s) && s->flags & SLAB_RED_ZONE) { > + if (offset < s->red_left_pad) > + return s->name; > + offset -= s->red_left_pad; > + } > + > + /* Allow address range falling entirely within object size. */ > + if (offset <= object_size && n <= object_size - offset) > + return NULL; > + > + return s->name; > +} > +#endif /* CONFIG_HARDENED_USERCOPY */ > + I compared this against what check_valid_pointer does for SLUB_DEBUG checking. I was hoping we could utilize that function to avoid duplication but a) __check_heap_object needs to allow accesses anywhere in the object, not just the beginning b) accessing page->objects is racy without the addition of locking in SLUB_DEBUG. Still, the ptr < page_address(page) check from __check_heap_object would be good to add to avoid generating garbage large offsets and trying to infer C math. With that, you can add Reviwed-by: Laura Abbott > static size_t __ksize(const void *object) > { > struct page *page; > Thanks, Laura --- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/mm/slub.c b/mm/slub.c index 7dee3d9..5370e4f 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3632,6 +3632,9 @@ const char *__check_heap_object(const void *ptr, unsigned long n, s = page->slab_cache; object_size = slab_ksize(s); + if (ptr < page_address(page)) + return s->name; + /* Find offset within object. */ offset = (ptr - page_address(page)) % s->size;