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arm64: standardize mmap_rnd() usage

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In preparation for splitting out ET_DYN ASLR, this refactors the use of
mmap_rnd() to be used similarly to arm and x86.  This additionally
enables mmap ASLR on legacy mmap layouts, which appeared to be missing
on arm64, and was already supported on arm.  Additionally removes a
copy/pasted declaration of an unused function.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kees Cook 2015-04-14 15:47:48 -07:00 committed by Linus Torvalds
parent 82168140bc
commit dd04cff1dc
2 changed files with 11 additions and 8 deletions
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1
arch/arm64/include/asm/elf.h
View file

@ -125,7 +125,6 @@ typedef struct user_fpsimd_state elf_fpregset_t;
* 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.
*/
extern unsigned long randomize_et_dyn(unsigned long base);
#define ELF_ET_DYN_BASE (2 * TASK_SIZE_64 / 3)
/*

18
arch/arm64/mm/mmap.c
View file

@ -49,15 +49,14 @@ static int mmap_is_legacy(void)
static unsigned long mmap_rnd(void)
{
unsigned long rnd = 0;
unsigned long rnd;
if (current->flags & PF_RANDOMIZE)
rnd = (long)get_random_int() & STACK_RND_MASK;
rnd = (unsigned long)get_random_int() & STACK_RND_MASK;
return rnd << PAGE_SHIFT;
}
static unsigned long mmap_base(void)
static unsigned long mmap_base(unsigned long rnd)
{
unsigned long gap = rlimit(RLIMIT_STACK);
@ -66,7 +65,7 @@ static unsigned long mmap_base(void)
else if (gap > MAX_GAP)
gap = MAX_GAP;
return PAGE_ALIGN(STACK_TOP - gap - mmap_rnd());
return PAGE_ALIGN(STACK_TOP - gap - rnd);
}
/*
@ -75,15 +74,20 @@ static unsigned long mmap_base(void)
*/
void arch_pick_mmap_layout(struct mm_struct *mm)
{
unsigned long random_factor = 0UL;
if (current->flags & PF_RANDOMIZE)
random_factor = mmap_rnd();
/*
* Fall back to the standard layout if the personality bit is set, or
* if the expected stack growth is unlimited:
*/
if (mmap_is_legacy()) {
mm->mmap_base = TASK_UNMAPPED_BASE;
mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
mm->get_unmapped_area = arch_get_unmapped_area;
} else {
mm->mmap_base = mmap_base();
mm->mmap_base = mmap_base(random_factor);
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
}
}