Commit dd04cff1 authored by Kees Cook's avatar Kees Cook Committed by Linus Torvalds
Browse files

arm64: standardize mmap_rnd() usage



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: default avatarKees Cook <keescook@chromium.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 82168140
......@@ -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)
/*
......
......@@ -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;
}
}
......
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