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authorKees Cook <keescook@chromium.org>2015-04-14 15:48:07 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-04-14 16:49:05 -0700
commitd1fd836dcf00d2028c700c7e44d2c23404062c90 (patch)
treef31f4ef7362328899d906258ec7a003a98579b91 /arch/s390/include/asm/elf.h
parentc6f5b001e65cdac592b65a08c5d2dd179cfba568 (diff)
downloadlinux-linaro-stable-d1fd836dcf00d2028c700c7e44d2c23404062c90.tar.gz
mm: split ET_DYN ASLR from mmap ASLR
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@chromium.org> Reported-by: 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>
Diffstat (limited to 'arch/s390/include/asm/elf.h')
-rw-r--r--arch/s390/include/asm/elf.h5
1 files changed, 2 insertions, 3 deletions
diff --git a/arch/s390/include/asm/elf.h b/arch/s390/include/asm/elf.h
index f8db4781a4c2..ff662155b2c4 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. */