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s390: 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, and extracts the
checking of PF_RANDOMIZE.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.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 15:47:57 -07:00 committed by Linus Torvalds
parent ed6322746a
commit 8e89a356fe
1 changed files with 23 additions and 11 deletions
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34
arch/s390/mm/mmap.c
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@ -62,20 +62,18 @@ static inline int mmap_is_legacy(void)
static unsigned long mmap_rnd(void)
{
if (!(current->flags & PF_RANDOMIZE))
return 0;
if (is_32bit_task())
return (get_random_int() & 0x7ff) << PAGE_SHIFT;
else
return (get_random_int() & mmap_rnd_mask) << PAGE_SHIFT;
}
static unsigned long mmap_base_legacy(void)
static unsigned long mmap_base_legacy(unsigned long rnd)
{
return TASK_UNMAPPED_BASE + mmap_rnd();
return TASK_UNMAPPED_BASE + rnd;
}
static inline unsigned long mmap_base(void)
static inline unsigned long mmap_base(unsigned long rnd)
{
unsigned long gap = rlimit(RLIMIT_STACK);
@ -84,7 +82,7 @@ static inline unsigned long mmap_base(void)
else if (gap > MAX_GAP)
gap = MAX_GAP;
gap &= PAGE_MASK;
return STACK_TOP - stack_maxrandom_size() - mmap_rnd() - gap;
return STACK_TOP - stack_maxrandom_size() - rnd - gap;
}
unsigned long
@ -187,7 +185,11 @@ unsigned long randomize_et_dyn(void)
if (!is_32bit_task())
/* Align to 4GB */
base &= ~((1UL << 32) - 1);
return base + mmap_rnd();
if (current->flags & PF_RANDOMIZE)
base += mmap_rnd();
return base;
}
#ifndef CONFIG_64BIT
@ -198,15 +200,20 @@ unsigned long randomize_et_dyn(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 = mmap_base_legacy();
mm->mmap_base = mmap_base_legacy(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;
}
}
@ -273,15 +280,20 @@ s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
*/
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 = mmap_base_legacy();
mm->mmap_base = mmap_base_legacy(random_factor);
mm->get_unmapped_area = s390_get_unmapped_area;
} else {
mm->mmap_base = mmap_base();
mm->mmap_base = mmap_base(random_factor);
mm->get_unmapped_area = s390_get_unmapped_area_topdown;
}
}