From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kees Cook Subject: [PATCH 1/5] arm: factor out mmap ASLR into mmap_rnd Date: Mon, 2 Mar 2015 16:19:44 -0800 Message-ID: <1425341988-1599-2-git-send-email-keescook@chromium.org> References: <1425341988-1599-1-git-send-email-keescook@chromium.org> Cc: Kees Cook , linux-kernel@vger.kernel.org, Russell King , Catalin Marinas , Will Deacon , Ralf Baechle , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Martin Schwidefsky , Heiko Carstens , linux390@de.ibm.com, x86@kernel.org, Alexander Viro , Oleg Nesterov , Andy Lutomirski , "David A. Long" , Andrey Ryabinin , Arun Chandran , Yann Droneaud , Min-Hua Che To: akpm@linux-foundation.org Return-path: In-Reply-To: <1425341988-1599-1-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 exporting per-arch mmap randomization functions, this moves the ASLR calculations for mmap on ARM into a separate routine. Signed-off-by: Kees Cook --- arch/arm/mm/mmap.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c index 5e85ed371364..0f8bc158f2c6 100644 --- a/arch/arm/mm/mmap.c +++ b/arch/arm/mm/mmap.c @@ -169,14 +169,21 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, return addr; } -void arch_pick_mmap_layout(struct mm_struct *mm) +static unsigned long mmap_rnd(void) { - unsigned long random_factor = 0UL; + unsigned long rnd = 0UL; /* 8 bits of randomness in 20 address space bits */ if ((current->flags & PF_RANDOMIZE) && !(current->personality & ADDR_NO_RANDOMIZE)) - random_factor = (get_random_int() % (1 << 8)) << PAGE_SHIFT; + rnd = (get_random_int() % (1 << 8)) << PAGE_SHIFT; + + return rnd; +} + +void arch_pick_mmap_layout(struct mm_struct *mm) +{ + unsigned long random_factor = mmap_rnd(); if (mmap_is_legacy()) { mm->mmap_base = TASK_UNMAPPED_BASE + random_factor; -- 1.9.1