[PATCH 1/5] arm: factor out mmap ASLR into mmap_rnd
From: Kees Cook <hidden>
Date: 2015-03-03 00:19:44
Also in:
linux-fsdevel, linux-mips, linuxppc-dev, lkml
Subsystem:
arm port, the rest · Maintainers:
Russell King, Linus Torvalds
In preparation for exporting per-arch mmap randomization functions, this moves the ASLR calculations for mmap on ARM into a separate routine. Signed-off-by: Kees Cook <redacted> --- arch/arm/mm/mmap.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index 5e85ed371364..0f8bc158f2c6 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c@@ -169,14 +169,21 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, return addr; } -void arch_pick_mmap_layout(struct mm_struct *mm) +static unsigned long mmap_rnd(void) { - unsigned long random_factor = 0UL; + unsigned long rnd = 0UL; /* 8 bits of randomness in 20 address space bits */ if ((current->flags & PF_RANDOMIZE) && !(current->personality & ADDR_NO_RANDOMIZE)) - random_factor = (get_random_int() % (1 << 8)) << PAGE_SHIFT; + rnd = (get_random_int() % (1 << 8)) << PAGE_SHIFT; + + return rnd; +} + +void arch_pick_mmap_layout(struct mm_struct *mm) +{ + unsigned long random_factor = mmap_rnd(); if (mmap_is_legacy()) { mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
--
1.9.1