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arm64: ASLR: Don't randomise text when randomise_va_space == 0 

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 by defining a constant ELF_ET_DYN_BASE. The randomisation of
mm->mmap_base is done by setup_new_exec -> arch_pick_mmap_layout ->
mmap_base -> mmap_rnd.

Signed-off-by: Arun Chandran <achandran@mvista.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Arun Chandran 2014-10-10 12:31:24 +01:00 committed by Catalin Marinas
parent e2b6b35ee7
commit 92980405f3
3 changed files with 3 additions and 7 deletions
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1
arch/arm64/Kconfig
View File

@ -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

4
arch/arm64/include/asm/elf.h
View File

@ -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

5
arch/arm64/kernel/process.c
View File

@ -378,8 +378,3 @@ 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);
}