From patchwork Tue Sep 21 06:11:49 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stephen Kitt X-Patchwork-Id: 12507379 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=-21.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 E57D6C433EF for ; Tue, 21 Sep 2021 08:40:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C110E610E8 for ; Tue, 21 Sep 2021 08:40:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231200AbhIUIle (ORCPT ); Tue, 21 Sep 2021 04:41:34 -0400 Received: from 2.mo2.mail-out.ovh.net ([188.165.53.149]:35317 "EHLO 2.mo2.mail-out.ovh.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230497AbhIUIld (ORCPT ); Tue, 21 Sep 2021 04:41:33 -0400 X-Greylist: delayed 4201 seconds by postgrey-1.27 at vger.kernel.org; Tue, 21 Sep 2021 04:41:33 EDT Received: from player774.ha.ovh.net (unknown [10.110.115.173]) by mo2.mail-out.ovh.net (Postfix) with ESMTP id 29244219C10 for ; Tue, 21 Sep 2021 08:12:27 +0200 (CEST) Received: from sk2.org (82-65-25-201.subs.proxad.net [82.65.25.201]) (Authenticated sender: steve@sk2.org) by player774.ha.ovh.net (Postfix) with ESMTPSA id 0922A226BB72E; Tue, 21 Sep 2021 06:12:10 +0000 (UTC) Authentication-Results: garm.ovh; auth=pass (GARM-96R0016908d250-99cb-4482-a321-0c67d65b58e6, AD8BB38DA772752445877EBF36A4BA27E0A99954) smtp.auth=steve@sk2.org X-OVh-ClientIp: 82.65.25.201 From: Stephen Kitt To: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , James Morris , "Serge E . Hallyn" Cc: linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Kees Cook , Stephen Kitt Subject: [PATCH] mm: Remove HARDENED_USERCOPY_FALLBACK Date: Tue, 21 Sep 2021 08:11:49 +0200 Message-Id: <20210921061149.1091163-1-steve@sk2.org> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-Ovh-Tracer-Id: 8631993114208077446 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedvtddrudeifedguddtgecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfqggfjpdevjffgvefmvefgnecuuegrihhlohhuthemucehtddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefhvffufffkofgggfestdekredtredttdenucfhrhhomhepufhtvghphhgvnhcumfhithhtuceoshhtvghvvgesshhkvddrohhrgheqnecuggftrfgrthhtvghrnhepgeevtdekjeekudevudevfeekgfehgeekgfetudfhjedtkeeltdffgeefvdefhfetnecuffhomhgrihhnpehgihhthhhusgdrtghomhenucfkpheptddrtddrtddrtddpkedvrdeihedrvdehrddvtddunecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmohguvgepshhmthhpqdhouhhtpdhhvghlohepphhlrgihvghrjeejgedrhhgrrdhovhhhrdhnvghtpdhinhgvtheptddrtddrtddrtddpmhgrihhlfhhrohhmpehsthgvvhgvsehskhdvrdhorhhgpdhrtghpthhtoheplhhinhhugidqshgvtghurhhithihqdhmohguuhhlvgesvhhgvghrrdhkvghrnhgvlhdrohhrgh Precedence: bulk List-ID: This has served its purpose and is no longer used. All usercopy violations appear to have been handled by now, any remaining instances (or new bugs) will cause copies to be rejected. This isn't a direct revert of commit 2d891fbc3bb6 ("usercopy: Allow strict enforcement of whitelists"); since usercopy_fallback is effectively 0, the fallback handling is removed too. This also removes the usercopy_fallback module parameter on slab_common. Link: https://github.com/KSPP/linux/issues/153 Signed-off-by: Stephen Kitt Suggested-by: Kees Cook Acked-by: Kees Cook Reviewed-by: Joel Stanley Acked-by: David Rientjes --- arch/powerpc/configs/skiroot_defconfig | 1 - include/linux/slab.h | 2 -- mm/slab.c | 13 ------------- mm/slab_common.c | 8 -------- mm/slub.c | 14 -------------- security/Kconfig | 14 -------------- 6 files changed, 52 deletions(-) base-commit: 368094df48e680fa51cedb68537408cfa64b788e diff --git a/arch/powerpc/configs/skiroot_defconfig b/arch/powerpc/configs/skiroot_defconfig index b806a5d3a695..c3ba614c973d 100644 --- a/arch/powerpc/configs/skiroot_defconfig +++ b/arch/powerpc/configs/skiroot_defconfig @@ -275,7 +275,6 @@ CONFIG_NLS_UTF8=y CONFIG_ENCRYPTED_KEYS=y CONFIG_SECURITY=y CONFIG_HARDENED_USERCOPY=y -# CONFIG_HARDENED_USERCOPY_FALLBACK is not set CONFIG_HARDENED_USERCOPY_PAGESPAN=y CONFIG_FORTIFY_SOURCE=y CONFIG_SECURITY_LOCKDOWN_LSM=y diff --git a/include/linux/slab.h b/include/linux/slab.h index 0c97d788762c..5b21515afae0 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -142,8 +142,6 @@ struct mem_cgroup; void __init kmem_cache_init(void); bool slab_is_available(void); -extern bool usercopy_fallback; - struct kmem_cache *kmem_cache_create(const char *name, unsigned int size, unsigned int align, slab_flags_t flags, void (*ctor)(void *)); diff --git a/mm/slab.c b/mm/slab.c index d0f725637663..4d826394ffcb 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -4207,19 +4207,6 @@ void __check_heap_object(const void *ptr, unsigned long n, struct page *page, n <= cachep->useroffset - offset + cachep->usersize) return; - /* - * If the copy is still within the allocated object, produce - * a warning instead of rejecting the copy. This is intended - * to be a temporary method to find any missing usercopy - * whitelists. - */ - if (usercopy_fallback && - offset <= cachep->object_size && - n <= cachep->object_size - offset) { - usercopy_warn("SLAB object", cachep->name, to_user, offset, n); - return; - } - usercopy_abort("SLAB object", cachep->name, to_user, offset, n); } #endif /* CONFIG_HARDENED_USERCOPY */ diff --git a/mm/slab_common.c b/mm/slab_common.c index a4a571428c51..925b00c1d4e8 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -37,14 +37,6 @@ LIST_HEAD(slab_caches); DEFINE_MUTEX(slab_mutex); struct kmem_cache *kmem_cache; -#ifdef CONFIG_HARDENED_USERCOPY -bool usercopy_fallback __ro_after_init = - IS_ENABLED(CONFIG_HARDENED_USERCOPY_FALLBACK); -module_param(usercopy_fallback, bool, 0400); -MODULE_PARM_DESC(usercopy_fallback, - "WARN instead of reject usercopy whitelist violations"); -#endif - static LIST_HEAD(slab_caches_to_rcu_destroy); static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work); static DECLARE_WORK(slab_caches_to_rcu_destroy_work, diff --git a/mm/slub.c b/mm/slub.c index 3f96e099817a..77f53e76a3c3 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -4125,7 +4125,6 @@ void __check_heap_object(const void *ptr, unsigned long n, struct page *page, { struct kmem_cache *s; unsigned int offset; - size_t object_size; bool is_kfence = is_kfence_address(ptr); ptr = kasan_reset_tag(ptr); @@ -4158,19 +4157,6 @@ void __check_heap_object(const void *ptr, unsigned long n, struct page *page, n <= s->useroffset - offset + s->usersize) return; - /* - * If the copy is still within the allocated object, produce - * a warning instead of rejecting the copy. This is intended - * to be a temporary method to find any missing usercopy - * whitelists. - */ - object_size = slab_ksize(s); - if (usercopy_fallback && - offset <= object_size && n <= object_size - offset) { - usercopy_warn("SLUB object", s->name, to_user, offset, n); - return; - } - usercopy_abort("SLUB object", s->name, to_user, offset, n); } #endif /* CONFIG_HARDENED_USERCOPY */ diff --git a/security/Kconfig b/security/Kconfig index 0ced7fd33e4d..d9698900c9b7 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -163,20 +163,6 @@ config HARDENED_USERCOPY or are part of the kernel text. This kills entire classes of heap overflow exploits and similar kernel memory exposures. -config HARDENED_USERCOPY_FALLBACK - bool "Allow usercopy whitelist violations to fallback to object size" - depends on HARDENED_USERCOPY - default y - help - This is a temporary option that allows missing usercopy whitelists - to be discovered via a WARN() to the kernel log, instead of - rejecting the copy, falling back to non-whitelisted hardened - usercopy that checks the slab allocation size instead of the - whitelist size. This option will be removed once it seems like - all missing usercopy whitelists have been identified and fixed. - Booting with "slab_common.usercopy_fallback=Y/N" can change - this setting. - config HARDENED_USERCOPY_PAGESPAN bool "Refuse to copy allocations that span multiple pages" depends on HARDENED_USERCOPY