From patchwork Thu May 23 14:08:42 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Potapenko X-Patchwork-Id: 10957745 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 BFFD115A6 for ; Thu, 23 May 2019 14:09:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A46D526E76 for ; Thu, 23 May 2019 14:09:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 986DC285FB; Thu, 23 May 2019 14:09:09 +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=-14.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,RCVD_IN_DNSWL_HI,USER_IN_DEF_DKIM_WL 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 82FBA26E76 for ; Thu, 23 May 2019 14:09:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730668AbfEWOJH (ORCPT ); Thu, 23 May 2019 10:09:07 -0400 Received: from mail-qt1-f201.google.com ([209.85.160.201]:56849 "EHLO mail-qt1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730323AbfEWOJG (ORCPT ); Thu, 23 May 2019 10:09:06 -0400 Received: by mail-qt1-f201.google.com with SMTP id 49so5383975qtn.23 for ; Thu, 23 May 2019 07:09:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=gdPkgObKlWOcdk8e46Oik49xVTWYBX7bQXMpu7mlMGs=; b=rXDxY0v/lcLDjFplx5Y7/QPVkoA04qniNWemRKZT0Zdqy5OBEhJjVJuUUaV29pBTB3 VS8jo8tOdan672tQQIhQnAGT3cmdY6wBeUeLQSj4sADPKAINNSV/21V8SWKqq1X5LzuV GYRwl821kh4NHSLftKaqcyzjagUgP5K4JXc3zu/LmfvjZjJOgxiAa/kawy+JXOpskcTt 20e6VYa67N/9/K9VQ6bw6sMXSFZnnstfWtGU6+zroCYSfBqwg1mbIDPo0NLzcEOQrpKS gZpnlYbcCfC/qKaxkL86vIe2Vp4whKOnpmGejWpxfWdlhsGdJm3j+LJy1WEmBUUulK5D Plkw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=gdPkgObKlWOcdk8e46Oik49xVTWYBX7bQXMpu7mlMGs=; b=WBs2XowFL5tbbeVcplctfe1LXC4JXWKJ1t4YE+gYSCMgw9dBFro0/DUnuNfngr/Hd0 8D8GG4CHh9DViWUwpeorklO85OgbSKEEYUOsFwNbXWRtedwaOpDjoZQ19Fi87fp5ntGb c1NeFonRiZqXIPYE4x/kioli3EFNC0DRoWwbu1E3tYAwEjSNrgvhfpwxHUH9GlHcc/tB iPeJZI+oxG01v97OXP0ClAop36bIVFu4FxTWBlNtRWt03cumeibWc68Xj7mic2abGdKj GXVMZpEqYj/it/vlqMRrVD5dcHUkjYAMQCXsXPX0AC2W17lNjWRrtoLihMhLWuVGZtGA qMOw== X-Gm-Message-State: APjAAAUX+Fht7NLaOIHbnGyyfE70YwduWv1t0NKrkub3UMFk8U2tj6S4 DuuYOAIa7Uk56U32eAPa0ixZr5yTXEk= X-Google-Smtp-Source: APXvYqwf2z6zZcNlfdnPdndyRBGBPUUEGL4p18pe71ljCZ4mCuadqwo7nQ1dTlYgVSfyU+Ol0TYu5b6w9rM= X-Received: by 2002:ac8:1b33:: with SMTP id y48mr80781800qtj.176.1558620545363; Thu, 23 May 2019 07:09:05 -0700 (PDT) Date: Thu, 23 May 2019 16:08:42 +0200 In-Reply-To: <20190523140844.132150-1-glider@google.com> Message-Id: <20190523140844.132150-2-glider@google.com> Mime-Version: 1.0 References: <20190523140844.132150-1-glider@google.com> X-Mailer: git-send-email 2.21.0.1020.gf2820cf01a-goog Subject: [PATCH v4 1/3] mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options From: Alexander Potapenko To: akpm@linux-foundation.org, cl@linux.com, keescook@chromium.org Cc: kernel-hardening@lists.openwall.com, linux-mm@kvack.org, linux-security-module@vger.kernel.org, Masahiro Yamada , Michal Hocko , James Morris , "Serge E. Hallyn" , Nick Desaulniers , Kostya Serebryany , Dmitry Vyukov , Sandeep Patil , Laura Abbott , Randy Dunlap , Jann Horn , Mark Rutland Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP The new options are needed to prevent possible information leaks and make control-flow bugs that depend on uninitialized values more deterministic. init_on_alloc=1 makes the kernel initialize newly allocated pages and heap objects with zeroes. Initialization is done at allocation time at the places where checks for __GFP_ZERO are performed. init_on_free=1 makes the kernel initialize freed pages and heap objects with zeroes upon their deletion. This helps to ensure sensitive data doesn't leak via use-after-free accesses. Both init_on_alloc=1 and init_on_free=1 guarantee that the allocator returns zeroed memory. The only exception is slab caches with constructors. Those are never zero-initialized to preserve their semantics. For SLOB allocator init_on_free=1 also implies init_on_alloc=1 behavior, i.e. objects are zeroed at both allocation and deallocation time. This is done because SLOB may otherwise return multiple freelist pointers in the allocated object. For SLAB and SLUB enabling either init_on_alloc or init_on_free leads to one-time initialization of the object. Both init_on_alloc and init_on_free default to zero, but those defaults can be overridden with CONFIG_INIT_ON_ALLOC_DEFAULT_ON and CONFIG_INIT_ON_FREE_DEFAULT_ON. Slowdown for the new features compared to init_on_free=0, init_on_alloc=0: hackbench, init_on_free=1: +7.62% sys time (st.err 0.74%) hackbench, init_on_alloc=1: +7.75% sys time (st.err 2.14%) Linux build with -j12, init_on_free=1: +8.38% wall time (st.err 0.39%) Linux build with -j12, init_on_free=1: +24.42% sys time (st.err 0.52%) Linux build with -j12, init_on_alloc=1: -0.13% wall time (st.err 0.42%) Linux build with -j12, init_on_alloc=1: +0.57% sys time (st.err 0.40%) The slowdown for init_on_free=0, init_on_alloc=0 compared to the baseline is within the standard error. The new features are also going to pave the way for hardware memory tagging (e.g. arm64's MTE), which will require both on_alloc and on_free hooks to set the tags for heap objects. With MTE, tagging will have the same cost as memory initialization. Although init_on_free is rather costly, there are paranoid use-cases where in-memory data lifetime is desired to be minimized. There are various arguments for/against the realism of the associated threat models, but given that we'll need the infrastructre for MTE anyway, and there are people who want wipe-on-free behavior no matter what the performance cost, it seems reasonable to include it in this series. Signed-off-by: Alexander Potapenko To: Andrew Morton To: Christoph Lameter To: Kees Cook Cc: Masahiro Yamada Cc: Michal Hocko Cc: James Morris Cc: "Serge E. Hallyn" Cc: Nick Desaulniers Cc: Kostya Serebryany Cc: Dmitry Vyukov Cc: Sandeep Patil Cc: Laura Abbott Cc: Randy Dunlap Cc: Jann Horn Cc: Mark Rutland Cc: linux-mm@kvack.org Cc: linux-security-module@vger.kernel.org Cc: kernel-hardening@lists.openwall.com --- v2: - unconditionally initialize pages in kernel_init_free_pages() - comment from Randy Dunlap: drop 'default false' lines from Kconfig.hardening v3: - don't call kernel_init_free_pages() from memblock_free_pages() - adopted some Kees' comments for the patch description v4: - use NULL instead of 0 in slab_alloc_node() (found by kbuild test robot) - don't write to NULL object in slab_alloc_node() (found by Android testing) --- .../admin-guide/kernel-parameters.txt | 8 +++ drivers/infiniband/core/uverbs_ioctl.c | 2 +- include/linux/mm.h | 22 +++++++ kernel/kexec_core.c | 2 +- mm/dmapool.c | 2 +- mm/page_alloc.c | 63 ++++++++++++++++--- mm/slab.c | 16 ++++- mm/slab.h | 16 +++++ mm/slob.c | 22 ++++++- mm/slub.c | 27 ++++++-- net/core/sock.c | 2 +- security/Kconfig.hardening | 14 +++++ 12 files changed, 175 insertions(+), 21 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 52e6fbb042cc..68fb6fa41cc1 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1673,6 +1673,14 @@ initrd= [BOOT] Specify the location of the initial ramdisk + init_on_alloc= [MM] Fill newly allocated pages and heap objects with + zeroes. + Format: 0 | 1 + Default set by CONFIG_INIT_ON_ALLOC_DEFAULT_ON. + init_on_free= [MM] Fill freed pages and heap objects with zeroes. + Format: 0 | 1 + Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON. + init_pkru= [x86] Specify the default memory protection keys rights register contents for all processes. 0x55555554 by default (disallow access to all but pkey 0). Can diff --git a/drivers/infiniband/core/uverbs_ioctl.c b/drivers/infiniband/core/uverbs_ioctl.c index 829b0c6944d8..61758201d9b2 100644 --- a/drivers/infiniband/core/uverbs_ioctl.c +++ b/drivers/infiniband/core/uverbs_ioctl.c @@ -127,7 +127,7 @@ __malloc void *_uverbs_alloc(struct uverbs_attr_bundle *bundle, size_t size, res = (void *)pbundle->internal_buffer + pbundle->internal_used; pbundle->internal_used = ALIGN(new_used, sizeof(*pbundle->internal_buffer)); - if (flags & __GFP_ZERO) + if (want_init_on_alloc(flags)) memset(res, 0, size); return res; } diff --git a/include/linux/mm.h b/include/linux/mm.h index 0e8834ac32b7..7733a341c0c4 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2685,6 +2685,28 @@ static inline void kernel_poison_pages(struct page *page, int numpages, int enable) { } #endif +#ifdef CONFIG_INIT_ON_ALLOC_DEFAULT_ON +DECLARE_STATIC_KEY_TRUE(init_on_alloc); +#else +DECLARE_STATIC_KEY_FALSE(init_on_alloc); +#endif +static inline bool want_init_on_alloc(gfp_t flags) +{ + if (static_branch_unlikely(&init_on_alloc)) + return true; + return flags & __GFP_ZERO; +} + +#ifdef CONFIG_INIT_ON_FREE_DEFAULT_ON +DECLARE_STATIC_KEY_TRUE(init_on_free); +#else +DECLARE_STATIC_KEY_FALSE(init_on_free); +#endif +static inline bool want_init_on_free(void) +{ + return static_branch_unlikely(&init_on_free); +} + extern bool _debug_pagealloc_enabled; static inline bool debug_pagealloc_enabled(void) diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index fd5c95ff9251..2f75dd0d0d81 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -315,7 +315,7 @@ static struct page *kimage_alloc_pages(gfp_t gfp_mask, unsigned int order) arch_kexec_post_alloc_pages(page_address(pages), count, gfp_mask); - if (gfp_mask & __GFP_ZERO) + if (want_init_on_alloc(gfp_mask)) for (i = 0; i < count; i++) clear_highpage(pages + i); } diff --git a/mm/dmapool.c b/mm/dmapool.c index 76a160083506..493d151067cb 100644 --- a/mm/dmapool.c +++ b/mm/dmapool.c @@ -381,7 +381,7 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags, #endif spin_unlock_irqrestore(&pool->lock, flags); - if (mem_flags & __GFP_ZERO) + if (want_init_on_alloc(mem_flags)) memset(retval, 0, pool->size); return retval; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 3b13d3914176..14ded6620aa0 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -135,6 +135,48 @@ unsigned long totalcma_pages __read_mostly; int percpu_pagelist_fraction; gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK; +#ifdef CONFIG_INIT_ON_ALLOC_DEFAULT_ON +DEFINE_STATIC_KEY_TRUE(init_on_alloc); +#else +DEFINE_STATIC_KEY_FALSE(init_on_alloc); +#endif +#ifdef CONFIG_INIT_ON_FREE_DEFAULT_ON +DEFINE_STATIC_KEY_TRUE(init_on_free); +#else +DEFINE_STATIC_KEY_FALSE(init_on_free); +#endif + +static int __init early_init_on_alloc(char *buf) +{ + int ret; + bool bool_result; + + if (!buf) + return -EINVAL; + ret = kstrtobool(buf, &bool_result); + if (bool_result) + static_branch_enable(&init_on_alloc); + else + static_branch_disable(&init_on_alloc); + return ret; +} +early_param("init_on_alloc", early_init_on_alloc); + +static int __init early_init_on_free(char *buf) +{ + int ret; + bool bool_result; + + if (!buf) + return -EINVAL; + ret = kstrtobool(buf, &bool_result); + if (bool_result) + static_branch_enable(&init_on_free); + else + static_branch_disable(&init_on_free); + return ret; +} +early_param("init_on_free", early_init_on_free); /* * A cached value of the page's pageblock's migratetype, used when the page is @@ -1089,6 +1131,14 @@ static int free_tail_pages_check(struct page *head_page, struct page *page) return ret; } +static void kernel_init_free_pages(struct page *page, int numpages) +{ + int i; + + for (i = 0; i < numpages; i++) + clear_highpage(page + i); +} + static __always_inline bool free_pages_prepare(struct page *page, unsigned int order, bool check_free) { @@ -1141,6 +1191,8 @@ static __always_inline bool free_pages_prepare(struct page *page, } arch_free_page(page, order); kernel_poison_pages(page, 1 << order, 0); + if (want_init_on_free()) + kernel_init_free_pages(page, 1 << order); if (debug_pagealloc_enabled()) kernel_map_pages(page, 1 << order, 0); @@ -2019,8 +2071,8 @@ static inline int check_new_page(struct page *page) static inline bool free_pages_prezeroed(void) { - return IS_ENABLED(CONFIG_PAGE_POISONING_ZERO) && - page_poisoning_enabled(); + return (IS_ENABLED(CONFIG_PAGE_POISONING_ZERO) && + page_poisoning_enabled()) || want_init_on_free(); } #ifdef CONFIG_DEBUG_VM @@ -2074,13 +2126,10 @@ inline void post_alloc_hook(struct page *page, unsigned int order, static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags, unsigned int alloc_flags) { - int i; - post_alloc_hook(page, order, gfp_flags); - if (!free_pages_prezeroed() && (gfp_flags & __GFP_ZERO)) - for (i = 0; i < (1 << order); i++) - clear_highpage(page + i); + if (!free_pages_prezeroed() && want_init_on_alloc(gfp_flags)) + kernel_init_free_pages(page, 1 << order); if (order && (gfp_flags & __GFP_COMP)) prep_compound_page(page, order); diff --git a/mm/slab.c b/mm/slab.c index 2915d912e89a..d42eb11f8f50 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -1853,6 +1853,14 @@ static bool set_objfreelist_slab_cache(struct kmem_cache *cachep, cachep->num = 0; + /* + * If slab auto-initialization on free is enabled, store the freelist + * off-slab, so that its contents don't end up in one of the allocated + * objects. + */ + if (unlikely(slab_want_init_on_free(cachep))) + return false; + if (cachep->ctor || flags & SLAB_TYPESAFE_BY_RCU) return false; @@ -3293,7 +3301,7 @@ slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid, local_irq_restore(save_flags); ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, caller); - if (unlikely(flags & __GFP_ZERO) && ptr) + if (unlikely(slab_want_init_on_alloc(flags, cachep)) && ptr) memset(ptr, 0, cachep->object_size); slab_post_alloc_hook(cachep, flags, 1, &ptr); @@ -3350,7 +3358,7 @@ slab_alloc(struct kmem_cache *cachep, gfp_t flags, unsigned long caller) objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller); prefetchw(objp); - if (unlikely(flags & __GFP_ZERO) && objp) + if (unlikely(slab_want_init_on_alloc(flags, cachep)) && objp) memset(objp, 0, cachep->object_size); slab_post_alloc_hook(cachep, flags, 1, &objp); @@ -3471,6 +3479,8 @@ void ___cache_free(struct kmem_cache *cachep, void *objp, struct array_cache *ac = cpu_cache_get(cachep); check_irq_off(); + if (unlikely(slab_want_init_on_free(cachep))) + memset(objp, 0, cachep->object_size); kmemleak_free_recursive(objp, cachep->flags); objp = cache_free_debugcheck(cachep, objp, caller); @@ -3558,7 +3568,7 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, cache_alloc_debugcheck_after_bulk(s, flags, size, p, _RET_IP_); /* Clear memory outside IRQ disabled section */ - if (unlikely(flags & __GFP_ZERO)) + if (unlikely(slab_want_init_on_alloc(flags, s))) for (i = 0; i < size; i++) memset(p[i], 0, s->object_size); diff --git a/mm/slab.h b/mm/slab.h index 43ac818b8592..24ae887359b8 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -524,4 +524,20 @@ static inline int cache_random_seq_create(struct kmem_cache *cachep, static inline void cache_random_seq_destroy(struct kmem_cache *cachep) { } #endif /* CONFIG_SLAB_FREELIST_RANDOM */ +static inline bool slab_want_init_on_alloc(gfp_t flags, struct kmem_cache *c) +{ + if (static_branch_unlikely(&init_on_alloc)) + return !(c->ctor); + else + return flags & __GFP_ZERO; +} + +static inline bool slab_want_init_on_free(struct kmem_cache *c) +{ + if (static_branch_unlikely(&init_on_free)) + return !(c->ctor); + else + return false; +} + #endif /* MM_SLAB_H */ diff --git a/mm/slob.c b/mm/slob.c index 84aefd9b91ee..1b565ee7f479 100644 --- a/mm/slob.c +++ b/mm/slob.c @@ -212,6 +212,19 @@ static void slob_free_pages(void *b, int order) free_pages((unsigned long)b, order); } +/* + * init_on_free=1 also implies initialization at allocation time. + * This is because newly allocated objects may contain freelist pointers + * somewhere in the middle. + */ +static inline bool slob_want_init_on_alloc(gfp_t flags, struct kmem_cache *c) +{ + if (static_branch_unlikely(&init_on_alloc) || + static_branch_unlikely(&init_on_free)) + return c ? (!c->ctor) : true; + return flags & __GFP_ZERO; +} + /* * slob_page_alloc() - Allocate a slob block within a given slob_page sp. * @sp: Page to look in. @@ -353,8 +366,6 @@ static void *slob_alloc(size_t size, gfp_t gfp, int align, int node) BUG_ON(!b); spin_unlock_irqrestore(&slob_lock, flags); } - if (unlikely(gfp & __GFP_ZERO)) - memset(b, 0, size); return b; } @@ -389,6 +400,9 @@ static void slob_free(void *block, int size) return; } + if (unlikely(want_init_on_free())) + memset(block, 0, size); + if (!slob_page_free(sp)) { /* This slob page is about to become partially free. Easy! */ sp->units = units; @@ -484,6 +498,8 @@ __do_kmalloc_node(size_t size, gfp_t gfp, int node, unsigned long caller) } kmemleak_alloc(ret, size, 1, gfp); + if (unlikely(slob_want_init_on_alloc(gfp, 0))) + memset(ret, 0, size); return ret; } @@ -582,6 +598,8 @@ static void *slob_alloc_node(struct kmem_cache *c, gfp_t flags, int node) WARN_ON_ONCE(flags & __GFP_ZERO); c->ctor(b); } + if (unlikely(slob_want_init_on_alloc(flags, c))) + memset(b, 0, c->size); kmemleak_alloc_recursive(b, c->size, 1, c->flags, flags); return b; diff --git a/mm/slub.c b/mm/slub.c index cd04dbd2b5d0..db8ed569a5cf 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1424,6 +1424,19 @@ static __always_inline bool slab_free_hook(struct kmem_cache *s, void *x) static inline bool slab_free_freelist_hook(struct kmem_cache *s, void **head, void **tail) { + + void *object; + void *next = *head; + void *old_tail = *tail ? *tail : *head; + + if (slab_want_init_on_free(s)) + do { + object = next; + next = get_freepointer(s, object); + memset(object, 0, s->size); + set_freepointer(s, object, next); + } while (object != old_tail); + /* * Compiler cannot detect this function can be removed if slab_free_hook() * evaluates to nothing. Thus, catch all relevant config debug options here. @@ -1433,9 +1446,7 @@ static inline bool slab_free_freelist_hook(struct kmem_cache *s, defined(CONFIG_DEBUG_OBJECTS_FREE) || \ defined(CONFIG_KASAN) - void *object; - void *next = *head; - void *old_tail = *tail ? *tail : *head; + next = *head; /* Head and tail of the reconstructed freelist */ *head = NULL; @@ -2741,8 +2752,14 @@ static __always_inline void *slab_alloc_node(struct kmem_cache *s, prefetch_freepointer(s, next_object); stat(s, ALLOC_FASTPATH); } + /* + * If the object has been wiped upon free, make sure it's fully + * initialized by zeroing out freelist pointer. + */ + if (unlikely(slab_want_init_on_free(s)) && object) + *(void **)object = NULL; - if (unlikely(gfpflags & __GFP_ZERO) && object) + if (unlikely(slab_want_init_on_alloc(gfpflags, s)) && object) memset(object, 0, s->object_size); slab_post_alloc_hook(s, gfpflags, 1, &object); @@ -3163,7 +3180,7 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, local_irq_enable(); /* Clear memory outside IRQ disabled fastpath loop */ - if (unlikely(flags & __GFP_ZERO)) { + if (unlikely(slab_want_init_on_alloc(flags, s))) { int j; for (j = 0; j < i; j++) diff --git a/net/core/sock.c b/net/core/sock.c index 75b1c950b49f..9ceb90c875bc 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1602,7 +1602,7 @@ static struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority, sk = kmem_cache_alloc(slab, priority & ~__GFP_ZERO); if (!sk) return sk; - if (priority & __GFP_ZERO) + if (want_init_on_alloc(priority)) sk_prot_clear_nulls(sk, prot->obj_size); } else sk = kmalloc(prot->obj_size, priority); diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening index 0a1d4ca314f4..87883e3e3c2a 100644 --- a/security/Kconfig.hardening +++ b/security/Kconfig.hardening @@ -159,6 +159,20 @@ config STACKLEAK_RUNTIME_DISABLE runtime to control kernel stack erasing for kernels built with CONFIG_GCC_PLUGIN_STACKLEAK. +config INIT_ON_ALLOC_DEFAULT_ON + bool "Set init_on_alloc=1 by default" + help + Enable init_on_alloc=1 by default, making the kernel initialize every + page and heap allocation with zeroes. + init_on_alloc can be overridden via command line. + +config INIT_ON_FREE_DEFAULT_ON + bool "Set init_on_free=1 by default" + help + Enable init_on_free=1 by default, making the kernel initialize freed + pages and slab memory with zeroes. + init_on_free can be overridden via command line. + endmenu endmenu From patchwork Thu May 23 14:08:43 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Potapenko X-Patchwork-Id: 10957749 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 DFBC116C1 for ; Thu, 23 May 2019 14:09:11 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C4AC728562 for ; Thu, 23 May 2019 14:09:11 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B9219285F2; Thu, 23 May 2019 14:09:11 +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=-14.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,RCVD_IN_DNSWL_HI,USER_IN_DEF_DKIM_WL 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 D177726E76 for ; 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Hallyn" , Souptick Joarder Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP Print the currently enabled stack and heap initialization modes. The possible options for stack are: - "all" for CONFIG_INIT_STACK_ALL; - "byref_all" for CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL; - "byref" for CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF; - "__user" for CONFIG_GCC_PLUGIN_STRUCTLEAK_USER; - "off" otherwise. Depending on the values of init_on_alloc and init_on_free boottime options we also report "heap alloc" and "heap free" as "on"/"off". In the init_on_free mode initializing pages at boot time may take some time, so print a notice about that as well. Signed-off-by: Alexander Potapenko Suggested-by: Kees Cook To: Andrew Morton To: Christoph Lameter Cc: Dmitry Vyukov Cc: James Morris Cc: Jann Horn Cc: Kostya Serebryany Cc: Laura Abbott Cc: Mark Rutland Cc: Masahiro Yamada Cc: Matthew Wilcox Cc: Nick Desaulniers Cc: Randy Dunlap Cc: Sandeep Patil Cc: "Serge E. Hallyn" Cc: Souptick Joarder Cc: kernel-hardening@lists.openwall.com Cc: linux-mm@kvack.org Cc: linux-security-module@vger.kernel.org --- init/main.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/init/main.c b/init/main.c index 5a2c69b4d7b3..90f721c58e61 100644 --- a/init/main.c +++ b/init/main.c @@ -519,6 +519,29 @@ static inline void initcall_debug_enable(void) } #endif +/* Report memory auto-initialization states for this boot. */ +void __init report_meminit(void) +{ + const char *stack; + + if (IS_ENABLED(CONFIG_INIT_STACK_ALL)) + stack = "all"; + else if (IS_ENABLED(CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL)) + stack = "byref_all"; + else if (IS_ENABLED(CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF)) + stack = "byref"; + else if (IS_ENABLED(CONFIG_GCC_PLUGIN_STRUCTLEAK_USER)) + stack = "__user"; + else + stack = "off"; + + pr_info("mem auto-init: stack:%s, heap alloc:%s, heap free:%s\n", + stack, want_init_on_alloc(GFP_KERNEL) ? "on" : "off", + want_init_on_free() ? "on" : "off"); + if (want_init_on_free()) + pr_info("Clearing system memory may take some time...\n"); +} + /* * Set up kernel memory allocators */ @@ -529,6 +552,7 @@ static void __init mm_init(void) * bigger than MAX_ORDER unless SPARSEMEM. */ page_ext_init_flatmem(); + report_meminit(); mem_init(); kmem_cache_init(); pgtable_init(); From patchwork Thu May 23 14:08:44 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Potapenko X-Patchwork-Id: 10957755 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 4B0E11395 for ; Thu, 23 May 2019 14:09:14 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3159E284B3 for ; Thu, 23 May 2019 14:09:14 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 257F7285EC; Thu, 23 May 2019 14:09:14 +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=-14.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,RCVD_IN_DNSWL_HI,USER_IN_DEF_DKIM_WL 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 6A2FF284B3 for ; Thu, 23 May 2019 14:09:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730495AbfEWOJN (ORCPT ); Thu, 23 May 2019 10:09:13 -0400 Received: from mail-qk1-f201.google.com ([209.85.222.201]:48560 "EHLO mail-qk1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730323AbfEWOJM (ORCPT ); Thu, 23 May 2019 10:09:12 -0400 Received: by mail-qk1-f201.google.com with SMTP id w184so5516778qka.15 for ; Thu, 23 May 2019 07:09:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=GrPd0Ehzkwgs8flG0McuJvkTnr/DIjfrIhDeOSvXnoY=; b=HxdHAURkSl4n27A0yrQIRU1ITTYPBWK1In1KGlmB43xzTe8tfXSa/dWul7q4I/3UzU zAXTkoEFSDGlQlwPxRKEPIsS4gx1GWROBjhSdaDe+osjq2IOHCxE8AK8vVLls9jsiCni Ah0o+mZ5lkt/KWNdF1YGyCq0Tn9kR2BizpDzBrgZFEG+PKOtey/cz+kMH+/+NJpItHf2 vzgiCe1wjnIMjaRo26wo/zwzLMMxV+51y6MNX1nzooG5KC1QggYgSZIVxhYV85G0/IFG eyM/9zRs+5DIGCsdt23RjOyg9gSR0BPyH9rKZ0GdAzhvalKjcPMUFbug9urWslsi51qX M31w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=GrPd0Ehzkwgs8flG0McuJvkTnr/DIjfrIhDeOSvXnoY=; b=gKPQMFkrXH7cCECXbP29FK/8TqR6plmJNaK4L2Rb0kGHjwNoERW3vh6fXi93yrx5Iz jjaVCdgZePVejt9W18+SJFNDCqIxXvmVbfSaWFDMF+hRb9EasBho2p3QuA3j/6oqn7zE 2D39yPqOUgyvP3g5kYDMgQVhhdX0d1hP8GO/7c6QXZ+AdAhmX6+MIegFm2UQWqYWBWYq GOt0TbStVlJ9BKqw263W7apMY/lYIQCL2kgKEP42eT2hzSI0GC7IKW3EwPtqMTPRqyG9 tCRkEye8kkV8uF26j43ui9clqS5Atqd6/VxQya9VP4JBZG+b0yHL+b4N2uz0NFTMH7Vn radA== X-Gm-Message-State: APjAAAUgp1pKz14PImi+gIY83IRK71xbPCTR2FDaKQ1HRIdI6Llk2s6r WzZ9xCv24jHbMMpaC5+VxqIamlU1KwA= X-Google-Smtp-Source: APXvYqwTc2z+TMaFN0UPPlnm9rius4RP7zoq7ED5Y5T2qgqHTis5h9UUibnhY+/7LWm7HuiK8P97MvS3qoo= X-Received: by 2002:a0c:95d5:: with SMTP id t21mr70859708qvt.215.1558620551451; Thu, 23 May 2019 07:09:11 -0700 (PDT) Date: Thu, 23 May 2019 16:08:44 +0200 In-Reply-To: <20190523140844.132150-1-glider@google.com> Message-Id: <20190523140844.132150-4-glider@google.com> Mime-Version: 1.0 References: <20190523140844.132150-1-glider@google.com> X-Mailer: git-send-email 2.21.0.1020.gf2820cf01a-goog Subject: [PATCH v4 3/3] lib: introduce test_meminit module From: Alexander Potapenko To: akpm@linux-foundation.org, cl@linux.com, keescook@chromium.org Cc: kernel-hardening@lists.openwall.com, linux-mm@kvack.org, linux-security-module@vger.kernel.org, Nick Desaulniers , Kostya Serebryany , Dmitry Vyukov , Sandeep Patil , Laura Abbott , Jann Horn Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP Add tests for heap and pagealloc initialization. These can be used to check init_on_alloc and init_on_free implementations as well as other approaches to initialization. Expected test output in the case the kernel provides heap initialization (e.g. when running with either init_on_alloc=1 or init_on_free=1): test_meminit: all 10 tests in test_pages passed test_meminit: all 40 tests in test_kvmalloc passed test_meminit: all 20 tests in test_kmemcache passed test_meminit: all 70 tests passed! Signed-off-by: Alexander Potapenko To: Kees Cook To: Andrew Morton To: Christoph Lameter Cc: Nick Desaulniers Cc: Kostya Serebryany Cc: Dmitry Vyukov Cc: Sandeep Patil Cc: Laura Abbott Cc: Jann Horn Cc: linux-mm@kvack.org Cc: linux-security-module@vger.kernel.org Cc: kernel-hardening@lists.openwall.com --- v3: - added example test output to the description - fixed a missing include spotted by kbuild test robot - added a missing MODULE_LICENSE - call do_kmem_cache_size() with size >= sizeof(void*) to unbreak debug builds --- lib/Kconfig.debug | 8 ++ lib/Makefile | 1 + lib/test_meminit.c | 208 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 217 insertions(+) create mode 100644 lib/test_meminit.c diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index fdfa173651eb..036e8ef03831 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -2043,6 +2043,14 @@ config TEST_STACKINIT If unsure, say N. +config TEST_MEMINIT + tristate "Test level of heap/page initialization" + help + Test if the kernel is zero-initializing heap and page allocations. + This can be useful to test init_on_alloc and init_on_free features. + + If unsure, say N. + endif # RUNTIME_TESTING_MENU config MEMTEST diff --git a/lib/Makefile b/lib/Makefile index fb7697031a79..05980c802500 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -91,6 +91,7 @@ obj-$(CONFIG_TEST_DEBUG_VIRTUAL) += test_debug_virtual.o obj-$(CONFIG_TEST_MEMCAT_P) += test_memcat_p.o obj-$(CONFIG_TEST_OBJAGG) += test_objagg.o obj-$(CONFIG_TEST_STACKINIT) += test_stackinit.o +obj-$(CONFIG_TEST_MEMINIT) += test_meminit.o obj-$(CONFIG_TEST_LIVEPATCH) += livepatch/ diff --git a/lib/test_meminit.c b/lib/test_meminit.c new file mode 100644 index 000000000000..d46e2b8c8e8e --- /dev/null +++ b/lib/test_meminit.c @@ -0,0 +1,208 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Test cases for SL[AOU]B/page initialization at alloc/free time. + */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include +#include +#include + +#define GARBAGE_INT (0x09A7BA9E) +#define GARBAGE_BYTE (0x9E) + +#define REPORT_FAILURES_IN_FN() \ + do { \ + if (failures) \ + pr_info("%s failed %d out of %d times\n", \ + __func__, failures, num_tests); \ + else \ + pr_info("all %d tests in %s passed\n", \ + num_tests, __func__); \ + } while (0) + +/* Calculate the number of uninitialized bytes in the buffer. */ +static int count_nonzero_bytes(void *ptr, size_t size) +{ + int i, ret = 0; + unsigned char *p = (unsigned char *)ptr; + + for (i = 0; i < size; i++) + if (p[i]) + ret++; + return ret; +} + +static void fill_with_garbage(void *ptr, size_t size) +{ + unsigned int *p = (unsigned int *)ptr; + int i = 0; + + while (size >= sizeof(*p)) { + p[i] = GARBAGE_INT; + i++; + size -= sizeof(*p); + } + if (size) + memset(&p[i], GARBAGE_BYTE, size); +} + +static int __init do_alloc_pages_order(int order, int *total_failures) +{ + struct page *page; + void *buf; + size_t size = PAGE_SIZE << order; + + page = alloc_pages(GFP_KERNEL, order); + buf = page_address(page); + fill_with_garbage(buf, size); + __free_pages(page, order); + + page = alloc_pages(GFP_KERNEL, order); + buf = page_address(page); + if (count_nonzero_bytes(buf, size)) + (*total_failures)++; + fill_with_garbage(buf, size); + __free_pages(page, order); + return 1; +} + +static int __init test_pages(int *total_failures) +{ + int failures = 0, num_tests = 0; + int i; + + for (i = 0; i < 10; i++) + num_tests += do_alloc_pages_order(i, &failures); + + REPORT_FAILURES_IN_FN(); + *total_failures += failures; + return num_tests; +} + +static int __init do_kmalloc_size(size_t size, int *total_failures) +{ + void *buf; + + buf = kmalloc(size, GFP_KERNEL); + fill_with_garbage(buf, size); + kfree(buf); + + buf = kmalloc(size, GFP_KERNEL); + if (count_nonzero_bytes(buf, size)) + (*total_failures)++; + fill_with_garbage(buf, size); + kfree(buf); + return 1; +} + +static int __init do_vmalloc_size(size_t size, int *total_failures) +{ + void *buf; + + buf = vmalloc(size); + fill_with_garbage(buf, size); + vfree(buf); + + buf = vmalloc(size); + if (count_nonzero_bytes(buf, size)) + (*total_failures)++; + fill_with_garbage(buf, size); + vfree(buf); + return 1; +} + +static int __init test_kvmalloc(int *total_failures) +{ + int failures = 0, num_tests = 0; + int i, size; + + for (i = 0; i < 20; i++) { + size = 1 << i; + num_tests += do_kmalloc_size(size, &failures); + num_tests += do_vmalloc_size(size, &failures); + } + + REPORT_FAILURES_IN_FN(); + *total_failures += failures; + return num_tests; +} + +#define CTOR_BYTES 4 +/* Initialize the first 4 bytes of the object. */ +void some_ctor(void *obj) +{ + memset(obj, 'A', CTOR_BYTES); +} + +static int __init do_kmem_cache_size(size_t size, bool want_ctor, + int *total_failures) +{ + struct kmem_cache *c; + void *buf; + int iter, bytes = 0; + int fail = 0; + + c = kmem_cache_create("test_cache", size, 1, 0, + want_ctor ? some_ctor : NULL); + for (iter = 0; iter < 10; iter++) { + buf = kmem_cache_alloc(c, GFP_KERNEL); + if (!want_ctor || iter == 0) + bytes = count_nonzero_bytes(buf, size); + if (want_ctor) { + /* + * Newly initialized memory must be initialized using + * the constructor. + */ + if (iter == 0 && bytes < CTOR_BYTES) + fail = 1; + } else { + if (bytes) + fail = 1; + } + fill_with_garbage(buf, size); + kmem_cache_free(c, buf); + } + kmem_cache_destroy(c); + + *total_failures += fail; + return 1; +} + +static int __init test_kmemcache(int *total_failures) +{ + int failures = 0, num_tests = 0; + int i, size; + + for (i = 0; i < 10; i++) { + size = 8 << i; + num_tests += do_kmem_cache_size(size, false, &failures); + num_tests += do_kmem_cache_size(size, true, &failures); + } + REPORT_FAILURES_IN_FN(); + *total_failures += failures; + return num_tests; +} + +static int __init test_meminit_init(void) +{ + int failures = 0, num_tests = 0; + + num_tests += test_pages(&failures); + num_tests += test_kvmalloc(&failures); + num_tests += test_kmemcache(&failures); + + if (failures == 0) + pr_info("all %d tests passed!\n", num_tests); + else + pr_info("failures: %d out of %d\n", failures, num_tests); + + return failures ? -EINVAL : 0; +} +module_init(test_meminit_init); + +MODULE_LICENSE("GPL");