[PATCH v3 03/10] arm64: standardize mmap_rnd() usage
From: Kees Cook <hidden>
Date: 2015-03-04 02:10:18
Also in:
linux-fsdevel, linux-mips, linuxppc-dev, lkml
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
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 <redacted> --- arch/arm64/include/asm/elf.h | 1 - arch/arm64/mm/mmap.c | 18 +++++++++++------- 2 files changed, 11 insertions(+), 8 deletions(-)
diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index 1f65be393139..f724db00b235 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h@@ -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) /*
diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
index 54922d1275b8..837626d0e142 100644
--- a/arch/arm64/mm/mmap.c
+++ b/arch/arm64/mm/mmap.c@@ -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 base) { 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 - base); } /*
@@ -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; } }
--
1.9.1