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=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 DA089C28CC0 for ; Wed, 29 May 2019 19:26:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AA8A7240F6 for ; Wed, 29 May 2019 19:26:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="Buw3FXSp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726085AbfE2T0T (ORCPT ); Wed, 29 May 2019 15:26:19 -0400 Received: from mail-pf1-f193.google.com ([209.85.210.193]:45729 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725917AbfE2T0T (ORCPT ); Wed, 29 May 2019 15:26:19 -0400 Received: by mail-pf1-f193.google.com with SMTP id s11so2250573pfm.12 for ; Wed, 29 May 2019 12:26:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=MqvScE+mpTeungkeSlvv3Q/uzBYTV0O7Qr5Vox35/hw=; b=Buw3FXSp4ANIXhiVaYcFq7ueT4hHfJzssIhWbmrncc4YnHk0oVg8OvJ0WvauqQALhB sBghG+54cb3Hrx24CLKE7D0oxQLoKUXTBDFyYSm5aD1WKGg3/759D66vG6dvvqaZZSbX RMrPVBwObsIhqMoSQcIrTNLUVIJxzJvUk8a8g= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=MqvScE+mpTeungkeSlvv3Q/uzBYTV0O7Qr5Vox35/hw=; b=jDOz01cQZ39M6nhl+EHyijIXC1KnyDNDA4lHyXNQo2TdhgJWi6eoMUERPKx1DW/Ulm kFcVHM7QJlnIatWh8975ncqeksuAlGy+wx//PjG4DcAewBKKi7NgM0OH9SMPwAJzr7Eo qtiW8J3vXZhZ0XSnK4P8a0LgDJ3Ab/E8vSylmyhKwAzLuaLnIH5JJKQt2iHl2W061cgo +tDBQYouxIp+7XD17aZ5p+NZn1AsN84xmfNedEkTjF76ce4TN7YZFq8P5ln/4uk7GOl8 sGmo8mKQTpX74Srte5jtTNPpEVmVPA+9CqUhsvmF4wYGQIPXBCPBliIf8HQv3k0OmeEX xmfA== X-Gm-Message-State: APjAAAWUDEFwTw50F0iYAdPvYZ/rczIzHD1SvRE+aw2fJ83K18USW9QL jyXCiTo77ALRlxVsTYv3jN2Y/g== X-Google-Smtp-Source: APXvYqwq6lC0O0O/2wGuHUis8CaujTzg5ED6XBldzBsiAKxCW18NlPMCdk/8ggb/wiv8TlnrM8H9eg== X-Received: by 2002:a62:585:: with SMTP id 127mr130528149pff.231.1559157973778; Wed, 29 May 2019 12:26:13 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id q17sm480361pfq.74.2019.05.29.12.26.12 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 29 May 2019 12:26:12 -0700 (PDT) Date: Wed, 29 May 2019 12:26:11 -0700 From: Kees Cook To: Alexandre Ghiti Cc: Andrew Morton , Christoph Hellwig , Russell King , Catalin Marinas , Will Deacon , Ralf Baechle , Paul Burton , James Hogan , Palmer Dabbelt , Albert Ou , Alexander Viro , Luis Chamberlain , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v4 08/14] arm: Use generic mmap top-down layout and brk randomization Message-ID: <201905291222.595685C3F0@keescook> References: <20190526134746.9315-1-alex@ghiti.fr> <20190526134746.9315-9-alex@ghiti.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190526134746.9315-9-alex@ghiti.fr> Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org 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. -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 > -- Kees Cook 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 E07A2C28CC0 for ; Wed, 29 May 2019 19:26:24 +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 B85AB240F7 for ; Wed, 29 May 2019 19:26:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="ZhwT+u94"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="Buw3FXSp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B85AB240F7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org 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-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=uoPUbMpPS1AIJdja6k8VSOKrqnkbNoRvVFtNB+pYal4=; b=ZhwT+u94La4vaW D7O5JFlLT+d4m1K1TSwXZij885bf+0Kujf+oVGKDbqOvI5yj6g4hJNaYJ3DGmP7jUOtpwSr2V9MKP z5CCo+I1azt8jEB+Z5MrXSmgcfbNm6GtrD2zpxWJ36+f0d2vEiAk/+Hb93uQloNP8iKv51DHXHdPU f6BdVuIaL6zhFKfNJgL8pSOytVvg8KhHVcRUtkmgAQ5vV/K+05+3UzI9+6GV0gJUbiYTV7xKvu4L8 xUlFLjfBvkBss1hJrwL6ZuF8gQLcbW/bGoJClz39h1ObOM6X2gv6LpeW0WJCem6haxDupo++h20uq COw/JUE/MK8sw4OII8dA==; 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 1hW4DK-0001hk-7v; Wed, 29 May 2019 19:26:18 +0000 Received: from mail-pg1-x542.google.com ([2607:f8b0:4864:20::542]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hW4DH-0001h6-HX for linux-riscv@lists.infradead.org; Wed, 29 May 2019 19:26:17 +0000 Received: by mail-pg1-x542.google.com with SMTP id w34so452393pga.12 for ; Wed, 29 May 2019 12:26:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=MqvScE+mpTeungkeSlvv3Q/uzBYTV0O7Qr5Vox35/hw=; b=Buw3FXSp4ANIXhiVaYcFq7ueT4hHfJzssIhWbmrncc4YnHk0oVg8OvJ0WvauqQALhB sBghG+54cb3Hrx24CLKE7D0oxQLoKUXTBDFyYSm5aD1WKGg3/759D66vG6dvvqaZZSbX RMrPVBwObsIhqMoSQcIrTNLUVIJxzJvUk8a8g= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=MqvScE+mpTeungkeSlvv3Q/uzBYTV0O7Qr5Vox35/hw=; b=Cd0XTLNQNZ/t/ZDJheVIpdkVahFNkSWIv2avgS2ItwbcH/gqTpeLMzg4Ebpy7wqwss BKxwjrQ8fCYoSvsoWNfrRq/8t3TyHFUec+1+SABGLMZyZSTpp6k0pVpsKmB7D7iVd20U It62GlQAfezE/E/Mv6Jpm1+3zNjFONO5S9BqCLK0piTLi1cA6b5D33a+FHUdp+A+22Dm pDcI8h1t8RodKBedY/rwh985kwzEqhy5NfkPJjxIEnlOTvwuldR9U8qzhDf/1bCCYxym GEvq+e+h2XbU0Lzprt4pmpiWCrir6iO5H8UxubP/0nbn+rrQnI6gr1ZVVi5Kpao4e5vu 4Piw== X-Gm-Message-State: APjAAAWTGa3c6ZoUXEKew5HjEfqtQTHGPCotABdcF50Xvel29c7YU+KL q9C0/3vCnqjcqlLdhsKO2KpOfQ== X-Google-Smtp-Source: APXvYqwq6lC0O0O/2wGuHUis8CaujTzg5ED6XBldzBsiAKxCW18NlPMCdk/8ggb/wiv8TlnrM8H9eg== X-Received: by 2002:a62:585:: with SMTP id 127mr130528149pff.231.1559157973778; Wed, 29 May 2019 12:26:13 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id q17sm480361pfq.74.2019.05.29.12.26.12 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 29 May 2019 12:26:12 -0700 (PDT) Date: Wed, 29 May 2019 12:26:11 -0700 From: Kees Cook To: Alexandre Ghiti Subject: Re: [PATCH v4 08/14] arm: Use generic mmap top-down layout and brk randomization Message-ID: <201905291222.595685C3F0@keescook> References: <20190526134746.9315-1-alex@ghiti.fr> <20190526134746.9315-9-alex@ghiti.fr> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190526134746.9315-9-alex@ghiti.fr> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190529_122615_613490_8BC4BFD2 X-CRM114-Status: GOOD ( 23.02 ) 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-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org 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. -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 > -- Kees Cook _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv 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 39E62C28CC0 for ; Wed, 29 May 2019 19:26:26 +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 035E5240F7 for ; Wed, 29 May 2019 19:26:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="qAt6maAX"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="Buw3FXSp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 035E5240F7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=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-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=BUbE0reV2GilF1ijr7pMmI6Qp4ic0/P+5lhfK6z5T+Q=; b=qAt6maAXBceyAF 6JFaPc4oZlk8qexllRccb05WVqs+iXudiX+PnLtkE2CcqqG0Ix6uxfU5FT7EZBPNeQTHJEwHA7zOa lfgKayc8XalAdIjy+JZaDBcJDymQ/qBCDa87O9IQkrikV+byLLFEMawAzOtfwijsxz/gxuveAnO79 xrULVTuyJhvJX6vownRO6G/kvEsrUwDlumxq3KBcgdAhqmzG+Hdrt/6Cj3Eo5pNjmd8kbucHvEbpv /TcZ2m5RhT9gYLvnglQ4lF2mg8ydJLwHhXB3a+mbqiWwdzP51sM0pqonCasYDivwH18gQ7LZpe7JR XaJZZiRQToeHz08OcHrg==; 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 1hW4DO-0001k1-7B; Wed, 29 May 2019 19:26:22 +0000 Received: from mail-pg1-x542.google.com ([2607:f8b0:4864:20::542]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hW4DL-0001iP-3l for linux-arm-kernel@lists.infradead.org; Wed, 29 May 2019 19:26:20 +0000 Received: by mail-pg1-x542.google.com with SMTP id t1so483351pgc.2 for ; Wed, 29 May 2019 12:26:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=MqvScE+mpTeungkeSlvv3Q/uzBYTV0O7Qr5Vox35/hw=; b=Buw3FXSp4ANIXhiVaYcFq7ueT4hHfJzssIhWbmrncc4YnHk0oVg8OvJ0WvauqQALhB sBghG+54cb3Hrx24CLKE7D0oxQLoKUXTBDFyYSm5aD1WKGg3/759D66vG6dvvqaZZSbX RMrPVBwObsIhqMoSQcIrTNLUVIJxzJvUk8a8g= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=MqvScE+mpTeungkeSlvv3Q/uzBYTV0O7Qr5Vox35/hw=; b=QcFdjESvPuQ/2rXAr0Btc1AzJgifvz4Twf6y8FefJx0MVRcsVUJA/2bsufilBY47Vv bN5d1avOPAzDOW/lOoggASI1Vy3bgwwWAiha2Xf68YmmiJUCJa+8Z1b/490pf2aJbY1i QwBMSEOuC6Ek3IRp9gtg2zXBJtXCzieBCVqBqnBl88E765gP9yd4a0u1rSTPTTv2MlUy Q3r8NdWxPLEBgfTkG/NMyKckgBisaHykpWzdh0jAQWdvq4G5notWGB2fthRApCmNqX00 d4R9BH93/1IHVsr5Knccqan6mH7wOO47UUGYUqhxRjRI0Zg/986meOKRgbNZBCRnrBsE XOJw== X-Gm-Message-State: APjAAAX7/zS9KnjTJR1hrV6hp/W4Tp0S0mYQnvRPlT0J3akh2pqGjkyd us9h245oEsvhhTeIVxF/+PmLtw== X-Google-Smtp-Source: APXvYqwq6lC0O0O/2wGuHUis8CaujTzg5ED6XBldzBsiAKxCW18NlPMCdk/8ggb/wiv8TlnrM8H9eg== X-Received: by 2002:a62:585:: with SMTP id 127mr130528149pff.231.1559157973778; Wed, 29 May 2019 12:26:13 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id q17sm480361pfq.74.2019.05.29.12.26.12 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 29 May 2019 12:26:12 -0700 (PDT) Date: Wed, 29 May 2019 12:26:11 -0700 From: Kees Cook To: Alexandre Ghiti Subject: Re: [PATCH v4 08/14] arm: Use generic mmap top-down layout and brk randomization Message-ID: <201905291222.595685C3F0@keescook> References: <20190526134746.9315-1-alex@ghiti.fr> <20190526134746.9315-9-alex@ghiti.fr> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190526134746.9315-9-alex@ghiti.fr> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190529_122619_155646_74FB45E0 X-CRM114-Status: GOOD ( 24.46 ) X-BeenThere: linux-arm-kernel@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-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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. -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 > -- Kees Cook _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel