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=-7.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED 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 CF0D4C04AB6 for ; Fri, 31 May 2019 04:50:17 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9C225263D5 for ; Fri, 31 May 2019 04:50:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="V0IORqDy" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9C225263D5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ghiti.fr Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=jB5BUIRsm+mEVdfSLDOtx/wLgWhkQBWOtS1/ZvtJU04=; b=V0IORqDyiT9X6toIE5HI8uZEs Iv5y7UFegwp5qzmFHVdsIJtxB3+lhZoC8voaAbgEGlKC1AHRfUFCiDU57kltPvYRWwG31+cTIeFa0 kMCPasPxlhfMj/xUNrTWQ4bDjOpjHzeo9Vb434Z/crBJL3cYJr/JflpKhSaQ1ZHZfcZxx6YfXBiMB lPj1uD3rlwTKuoJt+17zWHFqFyjoQj2NLLSbccM8oh1909RNoD8kOZpiPKbafIQzQNyWgpPFOK2fC OcJXq9jlLRn4Qq4bw2CzaSKv1KVLyeWSQFd+HfZgtnTGzOSLbx0CtqtucAERyKVk40cZRtqhh7h0K FsVtKR6SA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hWZUd-0008M4-LN; Fri, 31 May 2019 04:50:15 +0000 Received: from relay11.mail.gandi.net ([217.70.178.231]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hWZUU-00075H-Rv; Fri, 31 May 2019 04:50:09 +0000 Received: from [192.168.0.12] (127.19.86.79.rev.sfr.net [79.86.19.127]) (Authenticated sender: alex@ghiti.fr) by relay11.mail.gandi.net (Postfix) with ESMTPSA id 18921100004; Fri, 31 May 2019 04:49:29 +0000 (UTC) Subject: Re: [PATCH v4 08/14] arm: Use generic mmap top-down layout and brk randomization To: Kees Cook References: <20190526134746.9315-1-alex@ghiti.fr> <20190526134746.9315-9-alex@ghiti.fr> <201905291222.595685C3F0@keescook> From: Alex Ghiti Message-ID: Date: Fri, 31 May 2019 00:49:29 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <201905291222.595685C3F0@keescook> Content-Language: sv-FI X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190530_215007_218508_995A0736 X-CRM114-Status: GOOD ( 18.52 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Albert Ou , Catalin Marinas , Palmer Dabbelt , Will Deacon , Russell King , Ralf Baechle , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Paul Burton , linux-riscv@lists.infradead.org, Alexander Viro , James Hogan , linux-fsdevel@vger.kernel.org, Andrew Morton , linux-mips@vger.kernel.org, Christoph Hellwig , linux-arm-kernel@lists.infradead.org, Luis Chamberlain Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-riscv" Errors-To: linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org On 5/29/19 3:26 PM, Kees Cook wrote: > On Sun, May 26, 2019 at 09:47:40AM -0400, Alexandre Ghiti wrote: >> arm uses a top-down mmap layout by default that exactly fits the generic >> functions, so get rid of arch specific code and use the generic version >> by selecting ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT. >> As ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT selects ARCH_HAS_ELF_RANDOMIZE, >> use the generic version of arch_randomize_brk since it also fits. >> Note that this commit also removes the possibility for arm to have elf >> randomization and no MMU: without MMU, the security added by randomization >> is worth nothing. >> >> Signed-off-by: Alexandre Ghiti > Acked-by: Kees Cook > > It may be worth noting that STACK_RND_MASK is safe to remove here > because it matches the default that now exists in mm/util.c. Yes, thanks for pointing that. Thanks, Alex > > -Kees > >> --- >> arch/arm/Kconfig | 2 +- >> arch/arm/include/asm/processor.h | 2 -- >> arch/arm/kernel/process.c | 5 --- >> arch/arm/mm/mmap.c | 62 -------------------------------- >> 4 files changed, 1 insertion(+), 70 deletions(-) >> >> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig >> index 8869742a85df..27687a8c9fb5 100644 >> --- a/arch/arm/Kconfig >> +++ b/arch/arm/Kconfig >> @@ -6,7 +6,6 @@ config ARM >> select ARCH_CLOCKSOURCE_DATA >> select ARCH_HAS_DEBUG_VIRTUAL if MMU >> select ARCH_HAS_DEVMEM_IS_ALLOWED >> - select ARCH_HAS_ELF_RANDOMIZE >> select ARCH_HAS_FORTIFY_SOURCE >> select ARCH_HAS_KEEPINITRD >> select ARCH_HAS_KCOV >> @@ -29,6 +28,7 @@ config ARM >> select ARCH_SUPPORTS_ATOMIC_RMW >> select ARCH_USE_BUILTIN_BSWAP >> select ARCH_USE_CMPXCHG_LOCKREF >> + select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU >> select ARCH_WANT_IPC_PARSE_VERSION >> select BUILDTIME_EXTABLE_SORT if MMU >> select CLONE_BACKWARDS >> diff --git a/arch/arm/include/asm/processor.h b/arch/arm/include/asm/processor.h >> index 5d06f75ffad4..95b7688341c5 100644 >> --- a/arch/arm/include/asm/processor.h >> +++ b/arch/arm/include/asm/processor.h >> @@ -143,8 +143,6 @@ static inline void prefetchw(const void *ptr) >> #endif >> #endif >> >> -#define HAVE_ARCH_PICK_MMAP_LAYOUT >> - >> #endif >> >> #endif /* __ASM_ARM_PROCESSOR_H */ >> diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c >> index 72cc0862a30e..19a765db5f7f 100644 >> --- a/arch/arm/kernel/process.c >> +++ b/arch/arm/kernel/process.c >> @@ -322,11 +322,6 @@ unsigned long get_wchan(struct task_struct *p) >> return 0; >> } >> >> -unsigned long arch_randomize_brk(struct mm_struct *mm) >> -{ >> - return randomize_page(mm->brk, 0x02000000); >> -} >> - >> #ifdef CONFIG_MMU >> #ifdef CONFIG_KUSER_HELPERS >> /* >> diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c >> index 0b94b674aa91..b8d912ac9e61 100644 >> --- a/arch/arm/mm/mmap.c >> +++ b/arch/arm/mm/mmap.c >> @@ -17,43 +17,6 @@ >> ((((addr)+SHMLBA-1)&~(SHMLBA-1)) + \ >> (((pgoff)<> >> -/* gap between mmap and stack */ >> -#define MIN_GAP (128*1024*1024UL) >> -#define MAX_GAP ((STACK_TOP)/6*5) >> -#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) >> - >> -static int mmap_is_legacy(struct rlimit *rlim_stack) >> -{ >> - if (current->personality & ADDR_COMPAT_LAYOUT) >> - return 1; >> - >> - if (rlim_stack->rlim_cur == RLIM_INFINITY) >> - return 1; >> - >> - return sysctl_legacy_va_layout; >> -} >> - >> -static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) >> -{ >> - unsigned long gap = rlim_stack->rlim_cur; >> - unsigned long pad = stack_guard_gap; >> - >> - /* Account for stack randomization if necessary */ >> - if (current->flags & PF_RANDOMIZE) >> - pad += (STACK_RND_MASK << PAGE_SHIFT); >> - >> - /* Values close to RLIM_INFINITY can overflow. */ >> - if (gap + pad > gap) >> - gap += pad; >> - >> - if (gap < MIN_GAP) >> - gap = MIN_GAP; >> - else if (gap > MAX_GAP) >> - gap = MAX_GAP; >> - >> - return PAGE_ALIGN(STACK_TOP - gap - rnd); >> -} >> - >> /* >> * We need to ensure that shared mappings are correctly aligned to >> * avoid aliasing issues with VIPT caches. We need to ensure that >> @@ -181,31 +144,6 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, >> return addr; >> } >> >> -unsigned long arch_mmap_rnd(void) >> -{ >> - unsigned long rnd; >> - >> - rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); >> - >> - return rnd << PAGE_SHIFT; >> -} >> - >> -void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack) >> -{ >> - unsigned long random_factor = 0UL; >> - >> - if (current->flags & PF_RANDOMIZE) >> - random_factor = arch_mmap_rnd(); >> - >> - if (mmap_is_legacy(rlim_stack)) { >> - mm->mmap_base = TASK_UNMAPPED_BASE + random_factor; >> - mm->get_unmapped_area = arch_get_unmapped_area; >> - } else { >> - mm->mmap_base = mmap_base(random_factor, rlim_stack); >> - mm->get_unmapped_area = arch_get_unmapped_area_topdown; >> - } >> -} >> - >> /* >> * You really shouldn't be using read() or write() on /dev/mem. This >> * might go away in the future. >> -- >> 2.20.1 >> _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv