Commit ac24a02f authored Apr 14, 2015 by Kees Cook Committed by Trilok Soni Dec 01, 2015

mm: expose arch_mmap_rnd when available



When an architecture fully supports randomizing the ELF load location,
a per-arch mmap_rnd() function is used to find a randomized mmap base.
In preparation for randomizing the location of ET_DYN binaries
separately from mmap, this renames and exports these functions as
arch_mmap_rnd(). Additionally introduces CONFIG_ARCH_HAS_ELF_RANDOMIZE
for describing this feature on architectures that support it
(which is a superset of ARCH_BINFMT_ELF_RANDOMIZE_PIE, since s390
already supports a separated ET_DYN ASLR from mmap ASLR without the
ARCH_BINFMT_ELF_RANDOMIZE_PIE logic).

Change-Id: Iefab73a7499071e3984bf54814bdd047356f8c38
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Hector Marco-Gisbert <hecmargi@upv.es>
Cc: Russell King <linux@arm.linux.org.uk>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: "David A. Long" <dave.long@linaro.org>
Cc: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: Arun Chandran <achandran@mvista.com>
Cc: Yann Droneaud <ydroneaud@opteya.com>
Cc: Min-Hua Chen <orca.chen@gmail.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Alex Smith <alex@alex-smith.me.uk>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Vineeth Vijayan <vvijayan@mvista.com>
Cc: Jeff Bailey <jeffbailey@google.com>
Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Behan Webster <behanw@converseincode.com>
Cc: Ismael Ripoll <iripoll@upv.es>
Cc: Jan-Simon Mller <dl9pf@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Git-commit: 2b68f6caeac271620cd2f9362aeaed360e317df0
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


[sewango@codeaurora.org: resolve trivial merge conflicts]
Signed-off-by: Se Wang (Patrick) Oh <sewango@codeaurora.org>

parent 5ec78319

arch/Kconfig

+7 −0

Original line number	Diff line number	Diff line
		@@ -484,6 +484,13 @@ config HAVE_IRQ_EXIT_ON_IRQ_STACK
		This spares a stack switch and improves cache usage on softirq
		processing.

		config ARCH_HAS_ELF_RANDOMIZE
		bool
		help
		An architecture supports choosing randomized locations for
		stack, mmap, brk, and ET_DYN. Defined functions:
		- arch_mmap_rnd()

		#
		# ABI hall of shame
		#

arch/arm/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -3,6 +3,7 @@ config ARM
		default y
		select ARCH_BINFMT_ELF_RANDOMIZE_PIE
		select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
		select ARCH_HAS_ELF_RANDOMIZE
		select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
		select ARCH_HAVE_CUSTOM_GPIO_H
		select ARCH_MIGHT_HAVE_PC_PARPORT

arch/arm/mm/mmap.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -169,7 +169,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
		return addr;
		}

		static unsigned long mmap_rnd(void)
		unsigned long arch_mmap_rnd(void)
		{
		unsigned long rnd;

		@@ -184,7 +184,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
		unsigned long random_factor = 0UL;

		if (current->flags & PF_RANDOMIZE)
		random_factor = mmap_rnd();
		random_factor = arch_mmap_rnd();

		if (mmap_is_legacy()) {
		mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;

arch/arm64/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -2,6 +2,7 @@ config ARM64
		def_bool y
		select ARCH_BINFMT_ELF_RANDOMIZE_PIE
		select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
		select ARCH_HAS_ELF_RANDOMIZE
		select ARCH_HAS_SG_CHAIN
		select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
		select ARCH_USE_CMPXCHG_LOCKREF

arch/arm64/mm/mmap.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -47,7 +47,7 @@ static int mmap_is_legacy(void)
		return sysctl_legacy_va_layout;
		}

		static unsigned long mmap_rnd(void)
		unsigned long arch_mmap_rnd(void)
		{
		unsigned long rnd;

		@@ -77,7 +77,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
		unsigned long random_factor = 0UL;

		if (current->flags & PF_RANDOMIZE)
		random_factor = mmap_rnd();
		random_factor = arch_mmap_rnd();

		/*
		* Fall back to the standard layout if the personality bit is set, or