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tile: support ASLR fully 

With this change, tile Linux now supports address-space layout
randomization for shared objects, stack, heap and vdso.

Acked-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Tony Lu <zlu@tilera.com>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
This commit is contained in:
Tony Lu 2013-08-09 15:45:24 -04:00 committed by Chris Metcalf
parent 9b5bbf729d
commit b2eca4274c
2 changed files with 26 additions and 2 deletions
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4
arch/tile/include/asm/elf.h
View File

@ -137,6 +137,10 @@ do { \
NEW_AUX_ENT(AT_SYSINFO_EHDR, VDSO_BASE); \
} while (0)
struct mm_struct;
extern unsigned long arch_randomize_brk(struct mm_struct *mm);
#define arch_randomize_brk arch_randomize_brk
#ifdef CONFIG_COMPAT
#define COMPAT_ELF_PLATFORM "tilegx-m32"

24
arch/tile/mm/mmap.c
View File

@ -58,16 +58,36 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
#else
int is_32bit = 0;
#endif
unsigned long random_factor = 0UL;
/*
* 8 bits of randomness in 32bit mmaps, 24 address space bits
* 12 bits of randomness in 64bit mmaps, 28 address space bits
*/
if (current->flags & PF_RANDOMIZE) {
if (is_32bit)
random_factor = get_random_int() % (1<<8);
else
random_factor = get_random_int() % (1<<12);
random_factor <<= PAGE_SHIFT;
}
/*
* Use standard layout if the expected stack growth is unlimited
* or we are running native 64 bits.
*/
if (!is_32bit || rlimit(RLIMIT_STACK) == RLIM_INFINITY) {
mm->mmap_base = TASK_UNMAPPED_BASE;
if (rlimit(RLIMIT_STACK) == RLIM_INFINITY) {
mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
mm->get_unmapped_area = arch_get_unmapped_area;
} else {
mm->mmap_base = mmap_base(mm);
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
}
}
unsigned long arch_randomize_brk(struct mm_struct *mm)
{
unsigned long range_end = mm->brk + 0x02000000;
return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
}