The patch titled
Subject: mips: use generic mmap top-down layout and brk randomization
has been added to the -mm tree. Its filename is
mips-use-generic-mmap-top-down-layout-and-brk-randomization.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mips-use-generic-mmap-top-down-layout-and-brk-randomization.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mips-use-generic-mmap-top-down-layout-and-brk-randomization.patch
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------------------------------------------------------
From: Alexandre Ghiti <alex@xxxxxxxx>
Subject: mips: use generic mmap top-down layout and brk randomization
mips uses a top-down layout by default that exactly fits the generic
functions, so get rid of arch specific code and use the generic version by
selecting ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT.
As ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT selects ARCH_HAS_ELF_RANDOMIZE,
use the generic version of arch_randomize_brk since it also fits. Note
that this commit also removes the possibility for mips to have elf
randomization and no MMU: without MMU, the security added by randomization
is worth nothing.
Link: http://lkml.kernel.org/r/20190730055113.23635-14-alex@xxxxxxxx
Signed-off-by: Alexandre Ghiti <alex@xxxxxxxx>
Acked-by: Paul Burton <paul.burton@xxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Cc: Albert Ou <aou@xxxxxxxxxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: James Hogan <jhogan@xxxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/mips/Kconfig | 2
arch/mips/include/asm/processor.h | 5 -
arch/mips/mm/mmap.c | 96 ----------------------------
3 files changed, 1 insertion(+), 102 deletions(-)
--- a/arch/mips/include/asm/processor.h~mips-use-generic-mmap-top-down-layout-and-brk-randomization
+++ a/arch/mips/include/asm/processor.h
@@ -29,11 +29,6 @@
extern unsigned int vced_count, vcei_count;
-/*
- * MIPS does have an arch_pick_mmap_layout()
- */
-#define HAVE_ARCH_PICK_MMAP_LAYOUT 1
-
#ifdef CONFIG_32BIT
#ifdef CONFIG_KVM_GUEST
/* User space process size is limited to 1GB in KVM Guest Mode */
--- a/arch/mips/Kconfig~mips-use-generic-mmap-top-down-layout-and-brk-randomization
+++ a/arch/mips/Kconfig
@@ -5,7 +5,6 @@ config MIPS
select ARCH_32BIT_OFF_T if !64BIT
select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT
select ARCH_CLOCKSOURCE_DATA
- select ARCH_HAS_ELF_RANDOMIZE
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_HAS_UBSAN_SANITIZE_ALL
select ARCH_SUPPORTS_UPROBES
@@ -13,6 +12,7 @@ config MIPS
select ARCH_USE_CMPXCHG_LOCKREF if 64BIT
select ARCH_USE_QUEUED_RWLOCKS
select ARCH_USE_QUEUED_SPINLOCKS
+ select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
select ARCH_WANT_IPC_PARSE_VERSION
select BUILDTIME_EXTABLE_SORT
select CLONE_BACKWARDS
--- a/arch/mips/mm/mmap.c~mips-use-generic-mmap-top-down-layout-and-brk-randomization
+++ a/arch/mips/mm/mmap.c
@@ -16,49 +16,10 @@
#include <linux/random.h>
#include <linux/sched/signal.h>
#include <linux/sched/mm.h>
-#include <linux/sizes.h>
-#include <linux/compat.h>
unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */
EXPORT_SYMBOL(shm_align_mask);
-/* gap between mmap and stack */
-#define MIN_GAP (128*1024*1024UL)
-#define MAX_GAP ((STACK_TOP)/6*5)
-#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12))
-
-static int mmap_is_legacy(struct rlimit *rlim_stack)
-{
- if (current->personality & ADDR_COMPAT_LAYOUT)
- return 1;
-
- if (rlim_stack->rlim_cur == RLIM_INFINITY)
- return 1;
-
- return sysctl_legacy_va_layout;
-}
-
-static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
-{
- unsigned long gap = rlim_stack->rlim_cur;
- unsigned long pad = stack_guard_gap;
-
- /* Account for stack randomization if necessary */
- if (current->flags & PF_RANDOMIZE)
- pad += (STACK_RND_MASK << PAGE_SHIFT);
-
- /* Values close to RLIM_INFINITY can overflow. */
- if (gap + pad > gap)
- gap += pad;
-
- if (gap < MIN_GAP)
- gap = MIN_GAP;
- else if (gap > MAX_GAP)
- gap = MAX_GAP;
-
- return PAGE_ALIGN(STACK_TOP - gap - rnd);
-}
-
#define COLOUR_ALIGN(addr, pgoff) \
((((addr) + shm_align_mask) & ~shm_align_mask) + \
(((pgoff) << PAGE_SHIFT) & shm_align_mask))
@@ -156,63 +117,6 @@ unsigned long arch_get_unmapped_area_top
addr0, len, pgoff, flags, DOWN);
}
-unsigned long arch_mmap_rnd(void)
-{
- unsigned long rnd;
-
-#ifdef CONFIG_COMPAT
- if (TASK_IS_32BIT_ADDR)
- rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
- else
-#endif /* CONFIG_COMPAT */
- rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
-
- return rnd << PAGE_SHIFT;
-}
-
-void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
-{
- unsigned long random_factor = 0UL;
-
- if (current->flags & PF_RANDOMIZE)
- random_factor = arch_mmap_rnd();
-
- if (mmap_is_legacy(rlim_stack)) {
- mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
- mm->get_unmapped_area = arch_get_unmapped_area;
- } else {
- mm->mmap_base = mmap_base(random_factor, rlim_stack);
- mm->get_unmapped_area = arch_get_unmapped_area_topdown;
- }
-}
-
-static inline unsigned long brk_rnd(void)
-{
- unsigned long rnd = get_random_long();
-
- rnd = rnd << PAGE_SHIFT;
- /* 32MB for 32bit, 1GB for 64bit */
- if (!IS_ENABLED(CONFIG_64BIT) || is_compat_task())
- rnd = rnd & (SZ_32M - 1);
- else
- rnd = rnd & (SZ_1G - 1);
-
- return rnd;
-}
-
-unsigned long arch_randomize_brk(struct mm_struct *mm)
-{
- unsigned long base = mm->brk;
- unsigned long ret;
-
- ret = PAGE_ALIGN(base + brk_rnd());
-
- if (ret < mm->brk)
- return mm->brk;
-
- return ret;
-}
-
bool __virt_addr_valid(const volatile void *kaddr)
{
unsigned long vaddr = (unsigned long)kaddr;
_
Patches currently in -mm which might be from alex@xxxxxxxx are
mm-fs-move-randomize_stack_top-from-fs-to-mm.patch
arm64-make-use-of-is_compat_task-instead-of-hardcoding-this-test.patch
arm64-consider-stack-randomization-for-mmap-base-only-when-necessary.patch
arm64-mm-move-generic-mmap-layout-functions-to-mm.patch
arm64-mm-make-randomization-selected-by-generic-topdown-mmap-layout.patch
arm-properly-account-for-stack-randomization-and-stack-guard-gap.patch
arm-use-stack_top-when-computing-mmap-base-address.patch
arm-use-generic-mmap-top-down-layout-and-brk-randomization.patch
mips-properly-account-for-stack-randomization-and-stack-guard-gap.patch
mips-use-stack_top-when-computing-mmap-base-address.patch
mips-adjust-brk-randomization-offset-to-fit-generic-version.patch
mips-replace-arch-specific-way-to-determine-32bit-task-with-generic-version.patch
mips-use-generic-mmap-top-down-layout-and-brk-randomization.patch
riscv-make-mmap-allocation-top-down-by-default.patch
