From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kees Cook Subject: [PATCH v4 03/10] arm64: standardize mmap_rnd() usage Date: Wed, 4 Mar 2015 13:10:47 -0800 Message-ID: <1425503454-7531-4-git-send-email-keescook@chromium.org> References: <1425503454-7531-1-git-send-email-keescook@chromium.org> Cc: Kees Cook , Ingo Molnar , Michael Ellerman , Hector Marco-Gisbert , Ismael Ripoll , Russell King , Catalin Marinas , Will Deacon , Ralf Baechle , Benjamin Herrenschmidt , Paul Mackerras , Martin Schwidefsky , Heiko Carstens , linux390@de.ibm.com, x86@kernel.org, Alexander Viro , Andy Lutomirski , Oleg Nesterov , "David A. Long" , Andrey Ryabinin , Arun Chandran To: akpm@linux-foundation.org Return-path: In-Reply-To: <1425503454-7531-1-git-send-email-keescook@chromium.org> Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-subscribe: List-owner: List-post: List-archive: List-Id: linux-fsdevel.vger.kernel.org In preparation for splitting out ET_DYN ASLR, this refactors the use of mmap_rnd() to be used similarly to arm and x86. This additionally enables mmap ASLR on legacy mmap layouts, which appeared to be missing on arm64, and was already supported on arm. Additionally removes a copy/pasted declaration of an unused function. Signed-off-by: Kees Cook --- arch/arm64/include/asm/elf.h | 1 - arch/arm64/mm/mmap.c | 18 +++++++++++------- 2 files changed, 11 insertions(+), 8 deletions(-) diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h index 1f65be393139..f724db00b235 100644 --- a/arch/arm64/include/asm/elf.h +++ b/arch/arm64/include/asm/elf.h @@ -125,7 +125,6 @@ typedef struct user_fpsimd_state elf_fpregset_t; * 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. */ -extern unsigned long randomize_et_dyn(unsigned long base); #define ELF_ET_DYN_BASE (2 * TASK_SIZE_64 / 3) /* diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c index 54922d1275b8..ba776c01b552 100644 --- a/arch/arm64/mm/mmap.c +++ b/arch/arm64/mm/mmap.c @@ -49,15 +49,14 @@ static int mmap_is_legacy(void) static unsigned long mmap_rnd(void) { - unsigned long rnd = 0; + unsigned long rnd; - if (current->flags & PF_RANDOMIZE) - rnd = (long)get_random_int() & STACK_RND_MASK; + rnd = (unsigned long)get_random_int() & STACK_RND_MASK; return rnd << PAGE_SHIFT; } -static unsigned long mmap_base(void) +static unsigned long mmap_base(unsigned long rnd) { unsigned long gap = rlimit(RLIMIT_STACK); @@ -66,7 +65,7 @@ static unsigned long mmap_base(void) else if (gap > MAX_GAP) gap = MAX_GAP; - return PAGE_ALIGN(STACK_TOP - gap - mmap_rnd()); + return PAGE_ALIGN(STACK_TOP - gap - rnd); } /* @@ -75,15 +74,20 @@ static unsigned long mmap_base(void) */ void arch_pick_mmap_layout(struct mm_struct *mm) { + unsigned long random_factor = 0UL; + + if (current->flags & PF_RANDOMIZE) + random_factor = mmap_rnd(); + /* * Fall back to the standard layout if the personality bit is set, or * if the expected stack growth is unlimited: */ if (mmap_is_legacy()) { - mm->mmap_base = TASK_UNMAPPED_BASE; + mm->mmap_base = TASK_UNMAPPED_BASE + random_factor; mm->get_unmapped_area = arch_get_unmapped_area; } else { - mm->mmap_base = mmap_base(); + mm->mmap_base = mmap_base(random_factor); mm->get_unmapped_area = arch_get_unmapped_area_topdown; } } -- 1.9.1