From patchwork Thu Aug 9 19:21:06 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Konovalov X-Patchwork-Id: 10561729 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 259171057 for ; Thu, 9 Aug 2018 19:21:43 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 158922B947 for ; Thu, 9 Aug 2018 19:21:43 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1319F2B94E; Thu, 9 Aug 2018 19:21:43 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.8 required=2.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2EBFE2B947 for ; Thu, 9 Aug 2018 19:21:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727698AbeHIVry (ORCPT ); Thu, 9 Aug 2018 17:47:54 -0400 Received: from mail-wr1-f66.google.com ([209.85.221.66]:45717 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727694AbeHIVrx (ORCPT ); Thu, 9 Aug 2018 17:47:53 -0400 Received: by mail-wr1-f66.google.com with SMTP id f12-v6so6052813wrv.12 for ; Thu, 09 Aug 2018 12:21:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=uJ6q8PjPYcBwwEzFrC4nHyiwSQq7tYGhjlgVJlHyoQY=; b=qu6lSut+Tppg+jb4FypHvldSjPebTikzUuxLhQxjJWN+Rzv5jjaLu+4sLWEumdtMuo HYYljfxmbqPexcU05ecpIHnxaKv1B+VmTXv1URG97dq4ac5aFWD0Ak3hZZ5T2S3k8oGK R5QjT+nNQpVZzj2a9pgnletyBN0Vp6jZrfpS6zR1/ZoNq9dptRMR0f7H7Gh9z8iDXTem vjmV9QVZ1OpZcafwI9f2N5sgTLginRccYjSno5Emsu5/XOzwkZ2FvLYXtXgb4yQW7XUl qNqSyYoykgM3sEZsRVCpfvpbYGNH5R7MO6nNfA/XVKLFOdXzwIkVZ1raXIzeH+x+KyIn ezLw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=uJ6q8PjPYcBwwEzFrC4nHyiwSQq7tYGhjlgVJlHyoQY=; b=jf2ZKvBxpHvYvEAFcCps/Ur6+rW5lRuJq+6eM8kWSN2KojZ+6YHL6l6lXtROpSNQOw ufw46d0prwYF0HqrUG+MoT4qyS9NJ6uczDBi+/458h3aUYY4eOvl7HIIfcuxf5xQUYQi 146ry8Kox/tYk18KIfomPr6o/k4t4xPTuB82G9/voRIMRTMqKdFsjUeUoXoBnJUBuLjp XJ0Jfl89dKlz8jYMN4kfQWoULpUHvQVeLQ5rxrFnnbDFaL/RsyPMa6T7Pm1T9xeqK/hy y3gp22drPPkEnpYn3VsZWBGJrePXlnn9lg8jisHqjh5lEYyx/1nqNLMu0zIQ1jZEuwxf 87Lg== X-Gm-Message-State: AOUpUlHd1Br19kR+aosoz2mabYVJPOHZEDp00LEcjrDdHuBHkTYB0NPp bTdd2K+T7iBrNjrPFqh4VHkrRg== X-Google-Smtp-Source: AA+uWPzhM4NLx/ciSlWc45Gb41TTLEfQblnVo/0/nPYFyHekUHUJCDN42hqwXxXnom/Kul8tfyXEvA== X-Received: by 2002:adf:fd12:: with SMTP id e18-v6mr2142157wrr.280.1533842497944; Thu, 09 Aug 2018 12:21:37 -0700 (PDT) Received: from andreyknvl0.muc.corp.google.com ([2a00:79e0:15:10:84be:a42a:826d:c530]) by smtp.gmail.com with ESMTPSA id o14-v6sm14738797wmd.35.2018.08.09.12.21.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 09 Aug 2018 12:21:37 -0700 (PDT) From: Andrey Konovalov To: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Catalin Marinas , Will Deacon , Christoph Lameter , Andrew Morton , Mark Rutland , Nick Desaulniers , Marc Zyngier , Dave Martin , Ard Biesheuvel , "Eric W . Biederman" , Ingo Molnar , Paul Lawrence , Geert Uytterhoeven , Arnd Bergmann , "Kirill A . Shutemov" , Greg Kroah-Hartman , Kate Stewart , Mike Rapoport , kasan-dev@googlegroups.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sparse@vger.kernel.org, linux-mm@kvack.org, linux-kbuild@vger.kernel.org Cc: Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Jann Horn , Mark Brand , Chintan Pandya , Vishwath Mohan , Andrey Konovalov Subject: [PATCH v5 14/18] khwasan: add hooks implementation Date: Thu, 9 Aug 2018 21:21:06 +0200 Message-Id: <80bdd0848efe56424cd70258d8f7c1b271ad2e22.1533842385.git.andreyknvl@google.com> X-Mailer: git-send-email 2.18.0.597.ga71716f1ad-goog In-Reply-To: References: MIME-Version: 1.0 Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This commit adds KHWASAN specific hooks implementation and adjusts common KASAN and KHWASAN ones. 1. When a new slab cache is created, KHWASAN rounds up the size of the objects in this cache to KASAN_SHADOW_SCALE_SIZE (== 16). 2. On each kmalloc KHWASAN generates a random tag, sets the shadow memory, that corresponds to this object to this tag, and embeds this tag value into the top byte of the returned pointer. 3. On each kfree KHWASAN poisons the shadow memory with a random tag to allow detection of use-after-free bugs. The rest of the logic of the hook implementation is very much similar to the one provided by KASAN. KHWASAN saves allocation and free stack metadata to the slab object the same was KASAN does this. Signed-off-by: Andrey Konovalov --- mm/kasan/common.c | 82 +++++++++++++++++++++++++++++++++++----------- mm/kasan/kasan.h | 8 +++++ mm/kasan/khwasan.c | 40 ++++++++++++++++++++++ 3 files changed, 111 insertions(+), 19 deletions(-) diff --git a/mm/kasan/common.c b/mm/kasan/common.c index bed8e13c6e1d..938229b26f3a 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -140,6 +140,9 @@ void kasan_poison_shadow(const void *address, size_t size, u8 value) { void *shadow_start, *shadow_end; + /* Perform shadow offset calculation based on untagged address */ + address = reset_tag(address); + shadow_start = kasan_mem_to_shadow(address); shadow_end = kasan_mem_to_shadow(address + size); @@ -148,11 +151,20 @@ void kasan_poison_shadow(const void *address, size_t size, u8 value) void kasan_unpoison_shadow(const void *address, size_t size) { - kasan_poison_shadow(address, size, 0); + u8 tag = get_tag(address); + + /* Perform shadow offset calculation based on untagged address */ + address = reset_tag(address); + + kasan_poison_shadow(address, size, tag); if (size & KASAN_SHADOW_MASK) { u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size); - *shadow = size & KASAN_SHADOW_MASK; + + if (IS_ENABLED(CONFIG_KASAN_HW)) + *shadow = tag; + else + *shadow = size & KASAN_SHADOW_MASK; } } @@ -200,8 +212,9 @@ void kasan_unpoison_stack_above_sp_to(const void *watermark) void kasan_alloc_pages(struct page *page, unsigned int order) { - if (likely(!PageHighMem(page))) - kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order); + if (unlikely(PageHighMem(page))) + return; + kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order); } void kasan_free_pages(struct page *page, unsigned int order) @@ -235,6 +248,7 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size, slab_flags_t *flags) { unsigned int orig_size = *size; + unsigned int redzone_size = 0; int redzone_adjust; /* Add alloc meta. */ @@ -242,20 +256,20 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size, *size += sizeof(struct kasan_alloc_meta); /* Add free meta. */ - if (cache->flags & SLAB_TYPESAFE_BY_RCU || cache->ctor || - cache->object_size < sizeof(struct kasan_free_meta)) { + if (IS_ENABLED(CONFIG_KASAN_GENERIC) && + (cache->flags & SLAB_TYPESAFE_BY_RCU || cache->ctor || + cache->object_size < sizeof(struct kasan_free_meta))) { cache->kasan_info.free_meta_offset = *size; *size += sizeof(struct kasan_free_meta); } - redzone_adjust = optimal_redzone(cache->object_size) - - (*size - cache->object_size); + redzone_size = optimal_redzone(cache->object_size); + redzone_adjust = redzone_size - (*size - cache->object_size); if (redzone_adjust > 0) *size += redzone_adjust; *size = min_t(unsigned int, KMALLOC_MAX_SIZE, - max(*size, cache->object_size + - optimal_redzone(cache->object_size))); + max(*size, cache->object_size + redzone_size)); /* * If the metadata doesn't fit, don't enable KASAN at all. @@ -268,6 +282,8 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size, return; } + cache->align = round_up(cache->align, KASAN_SHADOW_SCALE_SIZE); + *flags |= SLAB_KASAN; } @@ -328,15 +344,30 @@ void *kasan_slab_alloc(struct kmem_cache *cache, void *object, gfp_t flags) return kasan_kmalloc(cache, object, cache->object_size, flags); } +static inline bool shadow_invalid(u8 tag, s8 shadow_byte) +{ + if (IS_ENABLED(CONFIG_KASAN_GENERIC)) + return shadow_byte < 0 || + shadow_byte >= KASAN_SHADOW_SCALE_SIZE; + else + return tag != (u8)shadow_byte; +} + static bool __kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip, bool quarantine) { s8 shadow_byte; + u8 tag; + void *tagged_object; unsigned long rounded_up_size; + tag = get_tag(object); + tagged_object = object; + object = reset_tag(object); + if (unlikely(nearest_obj(cache, virt_to_head_page(object), object) != object)) { - kasan_report_invalid_free(object, ip); + kasan_report_invalid_free(tagged_object, ip); return true; } @@ -345,20 +376,22 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object, return false; shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object)); - if (shadow_byte < 0 || shadow_byte >= KASAN_SHADOW_SCALE_SIZE) { - kasan_report_invalid_free(object, ip); + if (shadow_invalid(tag, shadow_byte)) { + kasan_report_invalid_free(tagged_object, ip); return true; } rounded_up_size = round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE); kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE); - if (!quarantine || unlikely(!(cache->flags & SLAB_KASAN))) + if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine) || + unlikely(!(cache->flags & SLAB_KASAN))) return false; set_track(&get_alloc_info(cache, object)->free_track, GFP_NOWAIT); quarantine_put(get_free_info(cache, object), cache); - return true; + + return IS_ENABLED(CONFIG_KASAN_GENERIC); } bool kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip) @@ -371,6 +404,7 @@ void *kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size, { unsigned long redzone_start; unsigned long redzone_end; + u8 tag; if (gfpflags_allow_blocking(flags)) quarantine_reduce(); @@ -383,14 +417,24 @@ void *kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size, redzone_end = round_up((unsigned long)object + cache->object_size, KASAN_SHADOW_SCALE_SIZE); - kasan_unpoison_shadow(object, size); + /* + * Objects with contructors and objects from SLAB_TYPESAFE_BY_RCU slabs + * have tags preassigned and are already tagged. + */ + if (IS_ENABLED(CONFIG_KASAN_HW) && + (cache->ctor || cache->flags & SLAB_TYPESAFE_BY_RCU)) + tag = get_tag(object); + else + tag = random_tag(); + + kasan_unpoison_shadow(set_tag(object, tag), size); kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start, KASAN_KMALLOC_REDZONE); if (cache->flags & SLAB_KASAN) set_track(&get_alloc_info(cache, object)->alloc_track, flags); - return (void *)object; + return set_tag(object, tag); } EXPORT_SYMBOL(kasan_kmalloc); @@ -440,7 +484,7 @@ void kasan_poison_kfree(void *ptr, unsigned long ip) page = virt_to_head_page(ptr); if (unlikely(!PageSlab(page))) { - if (ptr != page_address(page)) { + if (reset_tag(ptr) != page_address(page)) { kasan_report_invalid_free(ptr, ip); return; } @@ -453,7 +497,7 @@ void kasan_poison_kfree(void *ptr, unsigned long ip) void kasan_kfree_large(void *ptr, unsigned long ip) { - if (ptr != page_address(virt_to_head_page(ptr))) + if (reset_tag(ptr) != page_address(virt_to_head_page(ptr))) kasan_report_invalid_free(ptr, ip); /* The object will be poisoned by page_alloc. */ } diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index d60859d26be7..6f4f2ebf5f57 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -12,10 +12,18 @@ #define KHWASAN_TAG_INVALID 0xFE /* inaccessible memory tag */ #define KHWASAN_TAG_MAX 0xFD /* maximum value for random tags */ +#ifdef CONFIG_KASAN_GENERIC #define KASAN_FREE_PAGE 0xFF /* page was freed */ #define KASAN_PAGE_REDZONE 0xFE /* redzone for kmalloc_large allocations */ #define KASAN_KMALLOC_REDZONE 0xFC /* redzone inside slub object */ #define KASAN_KMALLOC_FREE 0xFB /* object was freed (kmem_cache_free/kfree) */ +#else +#define KASAN_FREE_PAGE KHWASAN_TAG_INVALID +#define KASAN_PAGE_REDZONE KHWASAN_TAG_INVALID +#define KASAN_KMALLOC_REDZONE KHWASAN_TAG_INVALID +#define KASAN_KMALLOC_FREE KHWASAN_TAG_INVALID +#endif + #define KASAN_GLOBAL_REDZONE 0xFA /* redzone for global variable */ /* diff --git a/mm/kasan/khwasan.c b/mm/kasan/khwasan.c index 9d91bf3c8246..6b1309278e39 100644 --- a/mm/kasan/khwasan.c +++ b/mm/kasan/khwasan.c @@ -106,15 +106,52 @@ void *khwasan_preset_slab_tag(struct kmem_cache *cache, unsigned int idx, void check_memory_region(unsigned long addr, size_t size, bool write, unsigned long ret_ip) { + u8 tag; + u8 *shadow_first, *shadow_last, *shadow; + void *untagged_addr; + + tag = get_tag((const void *)addr); + + /* Ignore accesses for pointers tagged with 0xff (native kernel + * pointer tag) to suppress false positives caused by kmap. + * + * Some kernel code was written to account for archs that don't keep + * high memory mapped all the time, but rather map and unmap particular + * pages when needed. Instead of storing a pointer to the kernel memory, + * this code saves the address of the page structure and offset within + * that page for later use. Those pages are then mapped and unmapped + * with kmap/kunmap when necessary and virt_to_page is used to get the + * virtual address of the page. For arm64 (that keeps the high memory + * mapped all the time), kmap is turned into a page_address call. + + * The issue is that with use of the page_address + virt_to_page + * sequence the top byte value of the original pointer gets lost (gets + * set to KHWASAN_TAG_KERNEL (0xFF). + */ + if (tag == KHWASAN_TAG_KERNEL) + return; + + untagged_addr = reset_tag((const void *)addr); + shadow_first = kasan_mem_to_shadow(untagged_addr); + shadow_last = kasan_mem_to_shadow(untagged_addr + size - 1); + + for (shadow = shadow_first; shadow <= shadow_last; shadow++) { + if (*shadow != tag) { + kasan_report(addr, size, write, ret_ip); + return; + } + } } #define DEFINE_HWASAN_LOAD_STORE(size) \ void __hwasan_load##size##_noabort(unsigned long addr) \ { \ + check_memory_region(addr, size, false, _RET_IP_); \ } \ EXPORT_SYMBOL(__hwasan_load##size##_noabort); \ void __hwasan_store##size##_noabort(unsigned long addr) \ { \ + check_memory_region(addr, size, true, _RET_IP_); \ } \ EXPORT_SYMBOL(__hwasan_store##size##_noabort) @@ -126,15 +163,18 @@ DEFINE_HWASAN_LOAD_STORE(16); void __hwasan_loadN_noabort(unsigned long addr, unsigned long size) { + check_memory_region(addr, size, false, _RET_IP_); } EXPORT_SYMBOL(__hwasan_loadN_noabort); void __hwasan_storeN_noabort(unsigned long addr, unsigned long size) { + check_memory_region(addr, size, true, _RET_IP_); } EXPORT_SYMBOL(__hwasan_storeN_noabort); void __hwasan_tag_memory(unsigned long addr, u8 tag, unsigned long size) { + kasan_poison_shadow((void *)addr, size, tag); } EXPORT_SYMBOL(__hwasan_tag_memory);