From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.outflux.net (smtp.outflux.net [IPv6:2001:19d0:2:6:c0de:0:736d:7470]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 03D281A0A3E for ; Thu, 5 Mar 2015 08:15:08 +1100 (AEDT) From: Kees Cook To: akpm@linux-foundation.org Subject: [PATCH v4 05/10] powerpc: standardize mmap_rnd() usage Date: Wed, 4 Mar 2015 13:10:49 -0800 Message-Id: <1425503454-7531-6-git-send-email-keescook@chromium.org> In-Reply-To: <1425503454-7531-1-git-send-email-keescook@chromium.org> References: <1425503454-7531-1-git-send-email-keescook@chromium.org> Cc: linux-mips@linux-mips.org, Arun Chandran , Heiko Carstens , linux-kernel@vger.kernel.org, Min-Hua Chen , Paul Mackerras , Ismael Ripoll , Yann Droneaud , linux-s390@vger.kernel.org, Russell King , Andrey Ryabinin , x86@kernel.org, Hector Marco-Gisbert , Ingo Molnar , "David A. Long" , Catalin Marinas , Borislav Petkov , Ben Hutchings , Kees Cook , Will Deacon , linux-fsdevel@vger.kernel.org, Alexander Viro , Michael Holzheu , linux-arm-kernel@lists.infradead.org, Jeff Bailey , Paul Burton , Oleg Nesterov , Ralf Baechle , Andy Lutomirski , Vineeth Vijayan , Markos Chandras , =?UTF-8?q?Jan-Simon=20M=C3=B6ller?= , Martin Schwidefsky , linux390@de.ibm.com, linuxppc-dev@lists.ozlabs.org, Alex Smith List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , In preparation for splitting out ET_DYN ASLR, this refactors the use of mmap_rnd() to be used similarly to arm and x86. Signed-off-by: Kees Cook Acked-by: Michael Ellerman --- Can mmap ASLR be safely enabled in the legacy mmap case here? Other archs use "mm->mmap_base = TASK_UNMAPPED_BASE + random_factor". --- arch/powerpc/mm/mmap.c | 26 +++++++++++++++----------- 1 file changed, 15 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c index cb8bdbe4972f..1ad2299d795d 100644 --- a/arch/powerpc/mm/mmap.c +++ b/arch/powerpc/mm/mmap.c @@ -55,19 +55,18 @@ static inline int mmap_is_legacy(void) static unsigned long mmap_rnd(void) { - unsigned long rnd = 0; + unsigned long rnd; + + /* 8MB for 32bit, 1GB for 64bit */ + if (is_32bit_task()) + rnd = (unsigned long)get_random_int() % (1<<(23-PAGE_SHIFT)); + else + rnd = (unsigned long)get_random_int() % (1<<(30-PAGE_SHIFT)); - if (current->flags & PF_RANDOMIZE) { - /* 8MB for 32bit, 1GB for 64bit */ - if (is_32bit_task()) - rnd = (long)(get_random_int() % (1<<(23-PAGE_SHIFT))); - else - rnd = (long)(get_random_int() % (1<<(30-PAGE_SHIFT))); - } return rnd << PAGE_SHIFT; } -static inline unsigned long mmap_base(void) +static inline unsigned long mmap_base(unsigned long rnd) { unsigned long gap = rlimit(RLIMIT_STACK); @@ -76,7 +75,7 @@ static inline unsigned long mmap_base(void) else if (gap > MAX_GAP) gap = MAX_GAP; - return PAGE_ALIGN(TASK_SIZE - gap - mmap_rnd()); + return PAGE_ALIGN(TASK_SIZE - gap - rnd); } /* @@ -85,6 +84,11 @@ static inline 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: @@ -93,7 +97,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm) mm->mmap_base = TASK_UNMAPPED_BASE; 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