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Commit 92980405 authored by Arun Chandran's avatar Arun Chandran Committed by Catalin Marinas
Browse files

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: default avatarArun Chandran <achandran@mvista.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent e2b6b35e

arch/arm64/Kconfig

+1 −0
Original line number Original line Diff line number Diff line 
config ARM64

config ARM64

	def_bool y

	def_bool y

	select ARCH_BINFMT_ELF_RANDOMIZE_PIE

	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE

	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE

	select ARCH_HAS_SG_CHAIN

	select ARCH_HAS_SG_CHAIN

	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST

	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST

arch/arm64/include/asm/elf.h

+2 −2
Original line number Original line Diff line number Diff line
@@ -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.

 * that it will "exec", and that there is sufficient room for the brk.

 */

 */

extern unsigned long randomize_et_dyn(unsigned long base);

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

 * 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")

#define COMPAT_ELF_PLATFORM		("v8l")

#endif

#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. */

/* AArch32 registers. */

#define COMPAT_ELF_NGREG		18

#define COMPAT_ELF_NGREG		18

arch/arm64/kernel/process.c

+0 −5
Original line number Original line Diff line number Diff line
@@ -378,8 +378,3 @@ unsigned long arch_randomize_brk(struct mm_struct *mm) 
{

{

	return randomize_base(mm->brk);

	return randomize_base(mm->brk);

}
 
}
 


unsigned long randomize_et_dyn(unsigned long base)

{

	return randomize_base(base);

}