From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754409AbdFWPEa (ORCPT ); Fri, 23 Jun 2017 11:04:30 -0400 Received: from mail-io0-f170.google.com ([209.85.223.170]:32873 "EHLO mail-io0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752606AbdFWPEZ (ORCPT ); Fri, 23 Jun 2017 11:04:25 -0400 MIME-Version: 1.0 In-Reply-To: References: <1498154792-49952-1-git-send-email-keescook@chromium.org> <1498154792-49952-3-git-send-email-keescook@chromium.org> From: Ard Biesheuvel Date: Fri, 23 Jun 2017 15:04:24 +0000 Message-ID: Subject: Re: [kernel-hardening] [PATCH 2/4] arm64: Reduce ELF_ET_DYN_BASE To: Kees Cook Cc: Andrew Morton , Russell King , Catalin Marinas , Will Deacon , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Martin Schwidefsky , Heiko Carstens , James Hogan , Pratyush Anand , Ingo Molnar , "linux-arm-kernel@lists.infradead.org" , linuxppc-dev , "linux-s390@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arch@vger.kernel.org" , "kernel-hardening@lists.openwall.com" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23 June 2017 at 14:02, Kees Cook wrote: > On Fri, Jun 23, 2017 at 6:52 AM, Kees Cook wrote: >> On Thu, Jun 22, 2017 at 11:57 PM, Ard Biesheuvel >> wrote: >>> Hi Kees, >>> >>> On 22 June 2017 at 18:06, Kees Cook wrote: >>>> Now that explicitly executed loaders are loaded in the mmap region, >>>> position PIE binaries lower in the address space to avoid possible >>>> collisions with mmap or stack regions. For 64-bit, align to 4GB to >>>> allow runtimes to use the entire 32-bit address space for 32-bit >>>> pointers. >>>> >>>> Signed-off-by: Kees Cook >>>> --- >>>> arch/arm64/include/asm/elf.h | 13 ++++++------- >>>> 1 file changed, 6 insertions(+), 7 deletions(-) >>>> >>>> diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h >>>> index 5d1700425efe..f742af8f7c42 100644 >>>> --- a/arch/arm64/include/asm/elf.h >>>> +++ b/arch/arm64/include/asm/elf.h >>>> @@ -113,12 +113,13 @@ >>>> #define ELF_EXEC_PAGESIZE PAGE_SIZE >>>> >>>> /* >>>> - * This is the location that an ET_DYN program is loaded if exec'ed. Typical >>>> - * use of this is to invoke "./ld.so someprog" to test out a new version of >>>> - * the loader. We need to make sure that it is out of the way of the program >>>> - * that it will "exec", and that there is sufficient room for the brk. >>>> + * This is the base location for PIE (ET_DYN with INTERP) loads. On >>>> + * 64-bit, this is raised to 4GB to leave the entire 32-bit address >>>> + * space open for things that want to use the area for 32-bit pointers. >>>> */ >>>> -#define ELF_ET_DYN_BASE (2 * TASK_SIZE_64 / 3) >>>> +#define ELF_ET_DYN_BASE (test_thread_flag(TIF_32BIT) ? \ >>>> + 0x000400000UL : \ >>>> + 0x100000000UL) >>>> >>> >>> Why are you merging this with the COMPAT definition? >> >> It seemed like the right thing to do since a single definition could >> handle both cases. Is there something I'm overlooking in the arm64 >> case? > > And like 5 minutes later there was a loud head-slapping noise in my > office. Durr, yeah, arm64 doesn't have to deal with a "native 32-bit" > mode, so the merge isn't needed. Yes yes, I will split it back up and > drop the thread flag test. > Oh, is that what I heard? From mboxrd@z Thu Jan 1 00:00:00 1970 MIME-Version: 1.0 In-Reply-To: References: <1498154792-49952-1-git-send-email-keescook@chromium.org> <1498154792-49952-3-git-send-email-keescook@chromium.org> From: Ard Biesheuvel Date: Fri, 23 Jun 2017 15:04:24 +0000 Message-ID: Content-Type: text/plain; charset="UTF-8" Subject: Re: [kernel-hardening] [PATCH 2/4] arm64: Reduce ELF_ET_DYN_BASE List-Archive: List-Post: To: Kees Cook Cc: Andrew Morton , Russell King , Catalin Marinas , Will Deacon , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Martin Schwidefsky , Heiko Carstens , James Hogan , Pratyush Anand , Ingo Molnar , "linux-arm-kernel@lists.infradead.org" , linuxppc-dev , "linux-s390@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arch@vger.kernel.org" , "kernel-hardening@lists.openwall.com" List-ID: On 23 June 2017 at 14:02, Kees Cook wrote: > On Fri, Jun 23, 2017 at 6:52 AM, Kees Cook wrote: >> On Thu, Jun 22, 2017 at 11:57 PM, Ard Biesheuvel >> wrote: >>> Hi Kees, >>> >>> On 22 June 2017 at 18:06, Kees Cook wrote: >>>> Now that explicitly executed loaders are loaded in the mmap region, >>>> position PIE binaries lower in the address space to avoid possible >>>> collisions with mmap or stack regions. For 64-bit, align to 4GB to >>>> allow runtimes to use the entire 32-bit address space for 32-bit >>>> pointers. >>>> >>>> Signed-off-by: Kees Cook >>>> --- >>>> arch/arm64/include/asm/elf.h | 13 ++++++------- >>>> 1 file changed, 6 insertions(+), 7 deletions(-) >>>> >>>> diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h >>>> index 5d1700425efe..f742af8f7c42 100644 >>>> --- a/arch/arm64/include/asm/elf.h >>>> +++ b/arch/arm64/include/asm/elf.h >>>> @@ -113,12 +113,13 @@ >>>> #define ELF_EXEC_PAGESIZE PAGE_SIZE >>>> >>>> /* >>>> - * This is the location that an ET_DYN program is loaded if exec'ed. Typical >>>> - * use of this is to invoke "./ld.so someprog" to test out a new version of >>>> - * the loader. We need to make sure that it is out of the way of the program >>>> - * that it will "exec", and that there is sufficient room for the brk. >>>> + * This is the base location for PIE (ET_DYN with INTERP) loads. On >>>> + * 64-bit, this is raised to 4GB to leave the entire 32-bit address >>>> + * space open for things that want to use the area for 32-bit pointers. >>>> */ >>>> -#define ELF_ET_DYN_BASE (2 * TASK_SIZE_64 / 3) >>>> +#define ELF_ET_DYN_BASE (test_thread_flag(TIF_32BIT) ? \ >>>> + 0x000400000UL : \ >>>> + 0x100000000UL) >>>> >>> >>> Why are you merging this with the COMPAT definition? >> >> It seemed like the right thing to do since a single definition could >> handle both cases. Is there something I'm overlooking in the arm64 >> case? > > And like 5 minutes later there was a loud head-slapping noise in my > office. Durr, yeah, arm64 doesn't have to deal with a "native 32-bit" > mode, so the merge isn't needed. Yes yes, I will split it back up and > drop the thread flag test. > Oh, is that what I heard? From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ard Biesheuvel Subject: Re: [kernel-hardening] [PATCH 2/4] arm64: Reduce ELF_ET_DYN_BASE Date: Fri, 23 Jun 2017 15:04:24 +0000 Message-ID: References: <1498154792-49952-1-git-send-email-keescook@chromium.org> <1498154792-49952-3-git-send-email-keescook@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: Received: from mail-io0-f170.google.com ([209.85.223.170]:34539 "EHLO mail-io0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753397AbdFWPEZ (ORCPT ); Fri, 23 Jun 2017 11:04:25 -0400 Received: by mail-io0-f170.google.com with SMTP id c201so42374962ioe.1 for ; Fri, 23 Jun 2017 08:04:25 -0700 (PDT) In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Kees Cook Cc: Andrew Morton , Russell King , Catalin Marinas , Will Deacon , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Martin Schwidefsky , Heiko Carstens , James Hogan , Pratyush Anand , Ingo Molnar , "linux-arm-kernel@lists.infradead.org" , linuxppc-dev , "linux-s390@vger.kernel.org" , "linux-kernel@vger.kernel.org" "linux-arch@vger.kernel.org" On 23 June 2017 at 14:02, Kees Cook wrote: > On Fri, Jun 23, 2017 at 6:52 AM, Kees Cook wrote: >> On Thu, Jun 22, 2017 at 11:57 PM, Ard Biesheuvel >> wrote: >>> Hi Kees, >>> >>> On 22 June 2017 at 18:06, Kees Cook wrote: >>>> Now that explicitly executed loaders are loaded in the mmap region, >>>> position PIE binaries lower in the address space to avoid possible >>>> collisions with mmap or stack regions. For 64-bit, align to 4GB to >>>> allow runtimes to use the entire 32-bit address space for 32-bit >>>> pointers. >>>> >>>> Signed-off-by: Kees Cook >>>> --- >>>> arch/arm64/include/asm/elf.h | 13 ++++++------- >>>> 1 file changed, 6 insertions(+), 7 deletions(-) >>>> >>>> diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h >>>> index 5d1700425efe..f742af8f7c42 100644 >>>> --- a/arch/arm64/include/asm/elf.h >>>> +++ b/arch/arm64/include/asm/elf.h >>>> @@ -113,12 +113,13 @@ >>>> #define ELF_EXEC_PAGESIZE PAGE_SIZE >>>> >>>> /* >>>> - * This is the location that an ET_DYN program is loaded if exec'ed. Typical >>>> - * use of this is to invoke "./ld.so someprog" to test out a new version of >>>> - * the loader. We need to make sure that it is out of the way of the program >>>> - * that it will "exec", and that there is sufficient room for the brk. >>>> + * This is the base location for PIE (ET_DYN with INTERP) loads. On >>>> + * 64-bit, this is raised to 4GB to leave the entire 32-bit address >>>> + * space open for things that want to use the area for 32-bit pointers. >>>> */ >>>> -#define ELF_ET_DYN_BASE (2 * TASK_SIZE_64 / 3) >>>> +#define ELF_ET_DYN_BASE (test_thread_flag(TIF_32BIT) ? \ >>>> + 0x000400000UL : \ >>>> + 0x100000000UL) >>>> >>> >>> Why are you merging this with the COMPAT definition? >> >> It seemed like the right thing to do since a single definition could >> handle both cases. Is there something I'm overlooking in the arm64 >> case? > > And like 5 minutes later there was a loud head-slapping noise in my > office. Durr, yeah, arm64 doesn't have to deal with a "native 32-bit" > mode, so the merge isn't needed. Yes yes, I will split it back up and > drop the thread flag test. > Oh, is that what I heard? From mboxrd@z Thu Jan 1 00:00:00 1970 From: ard.biesheuvel@linaro.org (Ard Biesheuvel) Date: Fri, 23 Jun 2017 15:04:24 +0000 Subject: [kernel-hardening] [PATCH 2/4] arm64: Reduce ELF_ET_DYN_BASE In-Reply-To: References: <1498154792-49952-1-git-send-email-keescook@chromium.org> <1498154792-49952-3-git-send-email-keescook@chromium.org> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 23 June 2017 at 14:02, Kees Cook wrote: > On Fri, Jun 23, 2017 at 6:52 AM, Kees Cook wrote: >> On Thu, Jun 22, 2017 at 11:57 PM, Ard Biesheuvel >> wrote: >>> Hi Kees, >>> >>> On 22 June 2017 at 18:06, Kees Cook wrote: >>>> Now that explicitly executed loaders are loaded in the mmap region, >>>> position PIE binaries lower in the address space to avoid possible >>>> collisions with mmap or stack regions. For 64-bit, align to 4GB to >>>> allow runtimes to use the entire 32-bit address space for 32-bit >>>> pointers. >>>> >>>> Signed-off-by: Kees Cook >>>> --- >>>> arch/arm64/include/asm/elf.h | 13 ++++++------- >>>> 1 file changed, 6 insertions(+), 7 deletions(-) >>>> >>>> diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h >>>> index 5d1700425efe..f742af8f7c42 100644 >>>> --- a/arch/arm64/include/asm/elf.h >>>> +++ b/arch/arm64/include/asm/elf.h >>>> @@ -113,12 +113,13 @@ >>>> #define ELF_EXEC_PAGESIZE PAGE_SIZE >>>> >>>> /* >>>> - * This is the location that an ET_DYN program is loaded if exec'ed. Typical >>>> - * use of this is to invoke "./ld.so someprog" to test out a new version of >>>> - * the loader. We need to make sure that it is out of the way of the program >>>> - * that it will "exec", and that there is sufficient room for the brk. >>>> + * This is the base location for PIE (ET_DYN with INTERP) loads. On >>>> + * 64-bit, this is raised to 4GB to leave the entire 32-bit address >>>> + * space open for things that want to use the area for 32-bit pointers. >>>> */ >>>> -#define ELF_ET_DYN_BASE (2 * TASK_SIZE_64 / 3) >>>> +#define ELF_ET_DYN_BASE (test_thread_flag(TIF_32BIT) ? \ >>>> + 0x000400000UL : \ >>>> + 0x100000000UL) >>>> >>> >>> Why are you merging this with the COMPAT definition? >> >> It seemed like the right thing to do since a single definition could >> handle both cases. Is there something I'm overlooking in the arm64 >> case? > > And like 5 minutes later there was a loud head-slapping noise in my > office. Durr, yeah, arm64 doesn't have to deal with a "native 32-bit" > mode, so the merge isn't needed. Yes yes, I will split it back up and > drop the thread flag test. > Oh, is that what I heard?