From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753800AbdFWNw3 (ORCPT ); Fri, 23 Jun 2017 09:52:29 -0400 Received: from mail-it0-f49.google.com ([209.85.214.49]:36957 "EHLO mail-it0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753269AbdFWNw0 (ORCPT ); Fri, 23 Jun 2017 09:52:26 -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: Kees Cook Date: Fri, 23 Jun 2017 06:52:24 -0700 X-Google-Sender-Auth: 59abgYzm5xKvdTBVpFbTJk1-f_Y Message-ID: Subject: Re: [kernel-hardening] [PATCH 2/4] arm64: Reduce ELF_ET_DYN_BASE To: Ard Biesheuvel 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 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? -Kees > >> #ifndef __ASSEMBLY__ >> >> @@ -173,8 +174,6 @@ extern int arch_setup_additional_pages(struct linux_binprm *bprm, >> >> #ifdef CONFIG_COMPAT >> >> -#define COMPAT_ELF_ET_DYN_BASE (2 * TASK_SIZE_32 / 3) >> - >> /* AArch32 registers. */ >> #define COMPAT_ELF_NGREG 18 >> typedef unsigned int compat_elf_greg_t; >> -- >> 2.7.4 >> -- Kees Cook Pixel Security From mboxrd@z Thu Jan 1 00:00:00 1970 MIME-Version: 1.0 Sender: keescook@google.com In-Reply-To: References: <1498154792-49952-1-git-send-email-keescook@chromium.org> <1498154792-49952-3-git-send-email-keescook@chromium.org> From: Kees Cook Date: Fri, 23 Jun 2017 06:52:24 -0700 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: Ard Biesheuvel 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 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? -Kees > >> #ifndef __ASSEMBLY__ >> >> @@ -173,8 +174,6 @@ extern int arch_setup_additional_pages(struct linux_binprm *bprm, >> >> #ifdef CONFIG_COMPAT >> >> -#define COMPAT_ELF_ET_DYN_BASE (2 * TASK_SIZE_32 / 3) >> - >> /* AArch32 registers. */ >> #define COMPAT_ELF_NGREG 18 >> typedef unsigned int compat_elf_greg_t; >> -- >> 2.7.4 >> -- Kees Cook Pixel Security From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kees Cook Subject: Re: [kernel-hardening] [PATCH 2/4] arm64: Reduce ELF_ET_DYN_BASE Date: Fri, 23 Jun 2017 06:52:24 -0700 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-it0-f41.google.com ([209.85.214.41]:36958 "EHLO mail-it0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752927AbdFWNw0 (ORCPT ); Fri, 23 Jun 2017 09:52:26 -0400 Received: by mail-it0-f41.google.com with SMTP id m47so8531683iti.0 for ; Fri, 23 Jun 2017 06:52:25 -0700 (PDT) In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Ard Biesheuvel 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 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? -Kees > >> #ifndef __ASSEMBLY__ >> >> @@ -173,8 +174,6 @@ extern int arch_setup_additional_pages(struct linux_binprm *bprm, >> >> #ifdef CONFIG_COMPAT >> >> -#define COMPAT_ELF_ET_DYN_BASE (2 * TASK_SIZE_32 / 3) >> - >> /* AArch32 registers. */ >> #define COMPAT_ELF_NGREG 18 >> typedef unsigned int compat_elf_greg_t; >> -- >> 2.7.4 >> -- Kees Cook Pixel Security From mboxrd@z Thu Jan 1 00:00:00 1970 From: keescook@chromium.org (Kees Cook) Date: Fri, 23 Jun 2017 06:52:24 -0700 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 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? -Kees > >> #ifndef __ASSEMBLY__ >> >> @@ -173,8 +174,6 @@ extern int arch_setup_additional_pages(struct linux_binprm *bprm, >> >> #ifdef CONFIG_COMPAT >> >> -#define COMPAT_ELF_ET_DYN_BASE (2 * TASK_SIZE_32 / 3) >> - >> /* AArch32 registers. */ >> #define COMPAT_ELF_NGREG 18 >> typedef unsigned int compat_elf_greg_t; >> -- >> 2.7.4 >> -- Kees Cook Pixel Security