The patch titled
Subject: arm64: mm: support ARCH_MMAP_RND_BITS
has been added to the -mm tree. Its filename is
arm64-mm-support-arch_mmap_rnd_bits.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/arm64-mm-support-arch_mmap_rnd_bits.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/arm64-mm-support-arch_mmap_rnd_bits.patch
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------------------------------------------------------
From: Daniel Cashman <dcashman@xxxxxxxxxx>
Subject: arm64: mm: support ARCH_MMAP_RND_BITS
arm64: arch_mmap_rnd() uses STACK_RND_MASK to generate the random offset
for the mmap base address. This value represents a compromise between
increased ASLR effectiveness and avoiding address-space fragmentation.
Replace it with a Kconfig option, which is sensibly bounded, so that
platform developers may choose where to place this compromise. Keep
default values as new minimums.
Signed-off-by: Daniel Cashman <dcashman@xxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Don Zickus <dzickus@xxxxxxxxxx>
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Heinrich Schuchardt <xypron.glpk@xxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Mark Salyzyn <salyzyn@xxxxxxxxxxx>
Cc: Jeff Vander Stoep <jeffv@xxxxxxxxxx>
Cc: Nick Kralevich <nnk@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Hector Marco-Gisbert <hecmargi@xxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc; Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc; Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm64/Kconfig | 23 +++++++++++++++++++++++
arch/arm64/mm/mmap.c | 6 ++++--
2 files changed, 27 insertions(+), 2 deletions(-)
diff -puN arch/arm64/Kconfig~arm64-mm-support-arch_mmap_rnd_bits arch/arm64/Kconfig
--- a/arch/arm64/Kconfig~arm64-mm-support-arch_mmap_rnd_bits
+++ a/arch/arm64/Kconfig
@@ -51,6 +51,8 @@ config ARM64
select HAVE_ARCH_JUMP_LABEL
select HAVE_ARCH_KASAN if SPARSEMEM_VMEMMAP
select HAVE_ARCH_KGDB
+ select HAVE_ARCH_MMAP_RND_BITS
+ select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_TRACEHOOK
select HAVE_BPF_JIT
@@ -104,6 +106,27 @@ config ARCH_PHYS_ADDR_T_64BIT
config MMU
def_bool y
+config ARCH_MMAP_RND_BITS_MIN
+ default 15 if ARM64_64K_PAGES
+ default 19
+
+config ARCH_MMAP_RND_BITS_MAX
+ default 20 if ARM64_64K_PAGES && ARCH_VA_BITS=39
+ default 24 if ARCH_VA_BITS=39
+ default 23 if ARM64_64K_PAGES && ARCH_VA_BITS=42
+ default 27 if ARCH_VA_BITS=42
+ default 29 if ARM64_64K_PAGES && ARCH_VA_BITS=48
+ default 33 if ARCH_VA_BITS=48
+ default 15 if ARM64_64K_PAGES
+ default 19
+
+config ARCH_MMAP_RND_COMPAT_BITS_MIN
+ default 7 if ARM64_64K_PAGES
+ default 11
+
+config ARCH_MMAP_RND_COMPAT_BITS_MAX
+ default 16
+
config NO_IOPORT_MAP
def_bool y if !PCI
diff -puN arch/arm64/mm/mmap.c~arm64-mm-support-arch_mmap_rnd_bits arch/arm64/mm/mmap.c
--- a/arch/arm64/mm/mmap.c~arm64-mm-support-arch_mmap_rnd_bits
+++ a/arch/arm64/mm/mmap.c
@@ -51,8 +51,10 @@ unsigned long arch_mmap_rnd(void)
{
unsigned long rnd;
- rnd = (unsigned long)get_random_int() & STACK_RND_MASK;
-
+ if (test_thread_flag(TIF_32BIT))
+ rnd = (unsigned long)get_random_int() % (1 << mmap_rnd_compat_bits);
+ else
+ rnd = (unsigned long)get_random_int() % (1 << mmap_rnd_bits);
return rnd << PAGE_SHIFT;
}
_
Patches currently in -mm which might be from dcashman@xxxxxxxxxx are
mm-mmap-add-new-proc-tunable-for-mmap_base-aslr.patch
arm-mm-support-arch_mmap_rnd_bits.patch
arm64-mm-support-arch_mmap_rnd_bits.patch
x86-mm-support-arch_mmap_rnd_bits.patch
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