Messages in this thread Patch in this message |  | | From | Arun Chandran <> | Subject | [PATCH v2] Arm64: ASLR: Don't randomise text when randomise_va_space == 0 | Date | Fri, 10 Oct 2014 17:01:24 +0530 |
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When user asks to turn off ASLR by writing "0" to /proc/sys/kernel/randomize_va_space there should not be any randomization to mmap base, stack, VDSO, libs, text and heap
Currently arm64 violates this behavior by randomising text. Fix this.
Signed-off-by: Arun Chandran <achandran@mvista.com> --- Changes since v1: removed randomize_et_dyn() ---
This can be tested using the code below
#include <stdio.h>
int main(int argc, char *argv) { printf("main = %p\n", main); return 0; }
* compile it possition independently aarch64-linux-gnu-gcc -fPIE -pie aslr.c -o aslr
* run it on the target
* Behavior before the patch
# for i in 1 2 3 4 5 ; do ./aslr ; done main = 0x557020a950 main = 0x5561e55950 main = 0x5563e3a950 main = 0x555af30950 main = 0x5592859950 # # echo 0 > /proc/sys/kernel/randomize_va_space # for i in 1 2 3 4 5 ; do ./aslr ; done main = 0x555927f950 main = 0x556829b950 main = 0x5566625950 main = 0x556b533950 main = 0x555c84d950
* Behavior after the patch
# for i in 1 2 3 4 5 ; do ./aslr ; done main = 0x7f91988950 main = 0x7fb17b6950 main = 0x7f7805a950 main = 0x7fa372e950 main = 0x7f9cc1e950 # # echo 0 > /proc/sys/kernel/randomize_va_space # for i in 1 2 3 4 5 ; do ./aslr ; done main = 0x5555555950 main = 0x5555555950 main = 0x5555555950 main = 0x5555555950 main = 0x5555555950 --- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/elf.h | 4 ++-- arch/arm64/kernel/process.c | 5 ----- 3 files changed, 3 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index fd4e81a..a2eefc9 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1,5 +1,6 @@ config ARM64 def_bool y + select ARCH_BINFMT_ELF_RANDOMIZE_PIE select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE select ARCH_HAS_SG_CHAIN select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h index 01d3aab..1f65be3 100644 --- a/arch/arm64/include/asm/elf.h +++ b/arch/arm64/include/asm/elf.h @@ -126,7 +126,7 @@ typedef struct user_fpsimd_state elf_fpregset_t; * that it will "exec", and that there is sufficient room for the brk. */ extern unsigned long randomize_et_dyn(unsigned long base); -#define ELF_ET_DYN_BASE (randomize_et_dyn(2 * TASK_SIZE_64 / 3)) +#define ELF_ET_DYN_BASE (2 * TASK_SIZE_64 / 3) /* * When the program starts, a1 contains a pointer to a function to be @@ -169,7 +169,7 @@ extern unsigned long arch_randomize_brk(struct mm_struct *mm); #define COMPAT_ELF_PLATFORM ("v8l") #endif -#define COMPAT_ELF_ET_DYN_BASE (randomize_et_dyn(2 * TASK_SIZE_32 / 3)) +#define COMPAT_ELF_ET_DYN_BASE (2 * TASK_SIZE_32 / 3) /* AArch32 registers. */ #define COMPAT_ELF_NGREG 18 diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 29d4869..d2edb12 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -403,8 +403,3 @@ unsigned long arch_randomize_brk(struct mm_struct *mm) { return randomize_base(mm->brk); } - -unsigned long randomize_et_dyn(unsigned long base) -{ - return randomize_base(base); -} -- 1.7.9.5
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