[Devel,05/11] ms/mm: expose arch_mmap_rnd when available

Submitted by Dmitry Safonov on May 18, 2017, 6:39 p.m.


Message ID 20170518183950.4372-6-dsafonov@virtuozzo.com
State New
Series "x86: C/R for ia32 tasks"
Headers show

Commit Message

Dmitry Safonov May 18, 2017, 6:39 p.m.
From: Kees Cook <keescook@chromium.org>

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

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>

[ms commit 2b68f6caeac2
 ported only x86 part as other archs need special care..]
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
 arch/Kconfig                  |  7 +++++++
 arch/x86/Kconfig              |  1 +
 arch/x86/mm/mmap.c            |  4 ++--
 include/linux/elf-randomize.h | 10 ++++++++++
 4 files changed, 20 insertions(+), 2 deletions(-)
 create mode 100644 include/linux/elf-randomize.h

Patch hide | download patch | download mbox

diff --git a/arch/Kconfig b/arch/Kconfig
index b5a4cb176d36..2b3b7d550a46 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -466,6 +466,13 @@  config HAVE_STACK_VALIDATION
 	  Architecture supports the 'objtool check' host tool command, which
 	  performs compile-time stack metadata validation.
+	bool
+	help
+	  An architecture supports choosing randomized locations for
+	  stack, mmap, brk, and ET_DYN. Defined functions:
+	  - arch_mmap_rnd()
 # ABI hall of shame
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6ad29a57f171..29902c4630b4 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -86,6 +86,7 @@  config X86
 	select ARCH_HAS_KCOV			if X86_64
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 0e426764499a..cb7cd6e3e686 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -65,7 +65,7 @@  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;
@@ -114,7 +114,7 @@  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();
 	mm->mmap_legacy_base = mmap_legacy_base(random_factor);
diff --git a/include/linux/elf-randomize.h b/include/linux/elf-randomize.h
new file mode 100644
index 000000000000..7a4eda02d2b1
--- /dev/null
+++ b/include/linux/elf-randomize.h
@@ -0,0 +1,10 @@ 
+static inline unsigned long arch_mmap_rnd(void) { return 0; }
+extern unsigned long arch_mmap_rnd(void);