[3.19.y-ckt stable] Patch "mm: split ET_DYN ASLR from mmap ASLR" has been added to the 3.19.y-ckt tree
Kamal Mostafa
kamal at canonical.com
Wed May 4 15:34:22 UTC 2016
This is a note to let you know that I have just added a patch titled
mm: split ET_DYN ASLR from mmap ASLR
to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree
which can be found at:
https://git.launchpad.net/~canonical-kernel/linux/+git/linux-stable-ckt/log/?h=linux-3.19.y-queue
This patch is scheduled to be released in version 3.19.8-ckt21.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Kamal
---8<------------------------------------------------------------
>From 885e95c3809710d50439541f760d461b40af9dfb Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook at chromium.org>
Date: Tue, 14 Apr 2015 15:48:07 -0700
Subject: mm: split ET_DYN ASLR from mmap ASLR
commit d1fd836dcf00d2028c700c7e44d2c23404062c90 upstream.
This fixes the "offset2lib" weakness in ASLR for arm, arm64, mips,
powerpc, and x86. The problem is that if there is a leak of ASLR from
the executable (ET_DYN), it means a leak of shared library offset as
well (mmap), and vice versa. Further details and a PoC of this attack
is available here:
http://cybersecurity.upv.es/attacks/offset2lib/offset2lib.html
With this patch, a PIE linked executable (ET_DYN) has its own ASLR
region:
$ ./show_mmaps_pie
54859ccd6000-54859ccd7000 r-xp ... /tmp/show_mmaps_pie
54859ced6000-54859ced7000 r--p ... /tmp/show_mmaps_pie
54859ced7000-54859ced8000 rw-p ... /tmp/show_mmaps_pie
7f75be764000-7f75be91f000 r-xp ... /lib/x86_64-linux-gnu/libc.so.6
7f75be91f000-7f75beb1f000 ---p ... /lib/x86_64-linux-gnu/libc.so.6
7f75beb1f000-7f75beb23000 r--p ... /lib/x86_64-linux-gnu/libc.so.6
7f75beb23000-7f75beb25000 rw-p ... /lib/x86_64-linux-gnu/libc.so.6
7f75beb25000-7f75beb2a000 rw-p ...
7f75beb2a000-7f75beb4d000 r-xp ... /lib64/ld-linux-x86-64.so.2
7f75bed45000-7f75bed46000 rw-p ...
7f75bed46000-7f75bed47000 r-xp ...
7f75bed47000-7f75bed4c000 rw-p ...
7f75bed4c000-7f75bed4d000 r--p ... /lib64/ld-linux-x86-64.so.2
7f75bed4d000-7f75bed4e000 rw-p ... /lib64/ld-linux-x86-64.so.2
7f75bed4e000-7f75bed4f000 rw-p ...
7fffb3741000-7fffb3762000 rw-p ... [stack]
7fffb377b000-7fffb377d000 r--p ... [vvar]
7fffb377d000-7fffb377f000 r-xp ... [vdso]
The change is to add a call the newly created arch_mmap_rnd() into the
ELF loader for handling ET_DYN ASLR in a separate region from mmap ASLR,
as was already done on s390. Removes CONFIG_BINFMT_ELF_RANDOMIZE_PIE,
which is no longer needed.
Signed-off-by: Kees Cook <keescook at chromium.org>
Reported-by: Hector Marco-Gisbert <hecmargi at upv.es>
Cc: Russell King <linux at arm.linux.org.uk>
Reviewed-by: Ingo Molnar <mingo at kernel.org>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Will Deacon <will.deacon at arm.com>
Cc: Ralf Baechle <ralf at linux-mips.org>
Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Cc: Paul Mackerras <paulus at samba.org>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Martin Schwidefsky <schwidefsky at de.ibm.com>
Cc: Heiko Carstens <heiko.carstens at de.ibm.com>
Cc: Alexander Viro <viro at zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg at redhat.com>
Cc: Andy Lutomirski <luto at amacapital.net>
Cc: "David A. Long" <dave.long at linaro.org>
Cc: Andrey Ryabinin <a.ryabinin at samsung.com>
Cc: Arun Chandran <achandran at mvista.com>
Cc: Yann Droneaud <ydroneaud at opteya.com>
Cc: Min-Hua Chen <orca.chen at gmail.com>
Cc: Paul Burton <paul.burton at imgtec.com>
Cc: Alex Smith <alex at alex-smith.me.uk>
Cc: Markos Chandras <markos.chandras at imgtec.com>
Cc: Vineeth Vijayan <vvijayan at mvista.com>
Cc: Jeff Bailey <jeffbailey at google.com>
Cc: Michael Holzheu <holzheu at linux.vnet.ibm.com>
Cc: Ben Hutchings <ben at decadent.org.uk>
Cc: Behan Webster <behanw at converseincode.com>
Cc: Ismael Ripoll <iripoll at upv.es>
Cc: Jan-Simon Mller <dl9pf at gmx.de>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
arch/arm/Kconfig | 1 -
arch/arm64/Kconfig | 1 -
arch/mips/Kconfig | 1 -
arch/powerpc/Kconfig | 1 -
arch/s390/include/asm/elf.h | 5 ++---
arch/s390/mm/mmap.c | 8 --------
arch/x86/Kconfig | 1 -
fs/Kconfig.binfmt | 3 ---
fs/binfmt_elf.c | 18 ++++--------------
9 files changed, 6 insertions(+), 33 deletions(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 8239faa..aec3ea4 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1,7 +1,6 @@
config ARM
bool
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
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 15de145..962b43b 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1,6 +1,5 @@
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_GCOV_PROFILE_ALL
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index f50c77f..72fa7c6 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -23,7 +23,6 @@ config MIPS
select HAVE_KRETPROBES
select HAVE_DEBUG_KMEMLEAK
select HAVE_SYSCALL_TRACEPOINTS
- select ARCH_BINFMT_ELF_RANDOMIZE_PIE
select ARCH_HAS_ELF_RANDOMIZE
select HAVE_ARCH_TRANSPARENT_HUGEPAGE if CPU_SUPPORTS_HUGEPAGES && 64BIT
select RTC_LIB if !MACH_LOONGSON
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index e3cd949..3827296 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -88,7 +88,6 @@ config PPC
select ARCH_MIGHT_HAVE_PC_PARPORT
select ARCH_MIGHT_HAVE_PC_SERIO
select BINFMT_ELF
- select ARCH_BINFMT_ELF_RANDOMIZE_PIE
select ARCH_HAS_ELF_RANDOMIZE
select OF
select OF_EARLY_FLATTREE
diff --git a/arch/s390/include/asm/elf.h b/arch/s390/include/asm/elf.h
index 2e63de8..d0db9d9 100644
--- a/arch/s390/include/asm/elf.h
+++ b/arch/s390/include/asm/elf.h
@@ -163,10 +163,9 @@ extern unsigned int vdso_enabled;
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. 64-bit
tasks are aligned to 4GB. */
-extern unsigned long randomize_et_dyn(void);
-#define ELF_ET_DYN_BASE (randomize_et_dyn() + (is_32bit_task() ? \
+#define ELF_ET_DYN_BASE (is_32bit_task() ? \
(STACK_TOP / 3 * 2) : \
- (STACK_TOP / 3 * 2) & ~((1UL << 32) - 1)))
+ (STACK_TOP / 3 * 2) & ~((1UL << 32) - 1))
/* This yields a mask that user programs can use to figure out what
instruction set this CPU supports. */
diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index 8c11536..bb3367c 100644
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -177,14 +177,6 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
return addr;
}
-unsigned long randomize_et_dyn(void)
-{
- if (current->flags & PF_RANDOMIZE)
- return arch_mmap_rnd();
-
- return 0UL;
-}
-
#ifndef CONFIG_64BIT
/*
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ea88e5d..9f6b332 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -85,7 +85,6 @@ config X86
select HAVE_CMPXCHG_DOUBLE
select HAVE_ARCH_KMEMCHECK
select HAVE_USER_RETURN_NOTIFIER
- select ARCH_BINFMT_ELF_RANDOMIZE_PIE
select ARCH_HAS_ELF_RANDOMIZE
select HAVE_ARCH_JUMP_LABEL
select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
index c055d56..58d892d 100644
--- a/fs/Kconfig.binfmt
+++ b/fs/Kconfig.binfmt
@@ -27,9 +27,6 @@ config COMPAT_BINFMT_ELF
bool
depends on COMPAT && BINFMT_ELF
-config ARCH_BINFMT_ELF_RANDOMIZE_PIE
- bool
-
config ARCH_BINFMT_ELF_STATE
bool
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index cd0dea9..41bf972 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -31,6 +31,7 @@
#include <linux/security.h>
#include <linux/random.h>
#include <linux/elf.h>
+#include <linux/elf-randomize.h>
#include <linux/utsname.h>
#include <linux/coredump.h>
#include <linux/sched.h>
@@ -910,21 +911,10 @@ static int load_elf_binary(struct linux_binprm *bprm)
* default mmap base, as well as whatever program they
* might try to exec. This is because the brk will
* follow the loader, and is not movable. */
-#ifdef CONFIG_ARCH_BINFMT_ELF_RANDOMIZE_PIE
- /* Memory randomization might have been switched off
- * in runtime via sysctl or explicit setting of
- * personality flags.
- * If that is the case, retain the original non-zero
- * load_bias value in order to establish proper
- * non-randomized mappings.
- */
+ load_bias = ELF_ET_DYN_BASE - vaddr;
if (current->flags & PF_RANDOMIZE)
- load_bias = 0;
- else
- load_bias = ELF_PAGESTART(ELF_ET_DYN_BASE - vaddr);
-#else
- load_bias = ELF_PAGESTART(ELF_ET_DYN_BASE - vaddr);
-#endif
+ load_bias += arch_mmap_rnd();
+ load_bias = ELF_PAGESTART(load_bias);
total_size = total_mapping_size(elf_phdata,
loc->elf_ex.e_phnum);
if (!total_size) {
--
2.7.4
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