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| author | dcashman <dcashman@google.com> | 2015-12-29 14:24:39 -0800 |
|---|---|---|
| committer | Ziyan <jaraidaniel@gmail.com> | 2016-10-29 01:33:53 +0200 |
| commit | 56ec74e215e7eed1634e82cdc2bec5e28422808a (patch) | |
| tree | 7e88d04f15a37216bc7fc7ecc628d31acf29e6fe /arch | |
| parent | b37549b9638e3d702eb6cd28e83767cccb4d164a (diff) | |
| download | kernel_samsung_tuna-56ec74e215e7eed1634e82cdc2bec5e28422808a.zip kernel_samsung_tuna-56ec74e215e7eed1634e82cdc2bec5e28422808a.tar.gz kernel_samsung_tuna-56ec74e215e7eed1634e82cdc2bec5e28422808a.tar.bz2 | |
FROMLIST: mm: mmap: Add new /proc tunable for mmap_base ASLR.
(cherry picked from commit https://lkml.org/lkml/2015/12/21/337)
ASLR only uses as few as 8 bits to generate the random offset for the
mmap base address on 32 bit architectures. This value was chosen to
prevent a poorly chosen value from dividing the address space in such
a way as to prevent large allocations. This may not be an issue on all
platforms. Allow the specification of a minimum number of bits so that
platforms desiring greater ASLR protection may determine where to place
the trade-off.
Bug: 24047224
Signed-off-by: Daniel Cashman <dcashman@android.com>
Signed-off-by: Daniel Cashman <dcashman@google.com>
Change-Id: Ic74424e07710cd9ccb4a02871a829d14ef0cc4bc
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/Kconfig | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index 228d761..14f6f15 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -181,4 +181,72 @@ config HAVE_ARCH_MUTEX_CPU_RELAX config HAVE_RCU_TABLE_FREE bool +config HAVE_ARCH_MMAP_RND_BITS + bool + help + An arch should select this symbol if it supports setting a variable + number of bits for use in establishing the base address for mmap + allocations, has MMU enabled and provides values for both: + - ARCH_MMAP_RND_BITS_MIN + - ARCH_MMAP_RND_BITS_MAX + +config ARCH_MMAP_RND_BITS_MIN + int + +config ARCH_MMAP_RND_BITS_MAX + int + +config ARCH_MMAP_RND_BITS_DEFAULT + int + +config ARCH_MMAP_RND_BITS + int "Number of bits to use for ASLR of mmap base address" if EXPERT + range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX + default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT + default ARCH_MMAP_RND_BITS_MIN + depends on HAVE_ARCH_MMAP_RND_BITS + help + This value can be used to select the number of bits to use to + determine the random offset to the base address of vma regions + resulting from mmap allocations. This value will be bounded + by the architecture's minimum and maximum supported values. + + This value can be changed after boot using the + /proc/sys/vm/mmap_rnd_bits tunable + +config HAVE_ARCH_MMAP_RND_COMPAT_BITS + bool + help + An arch should select this symbol if it supports running applications + in compatibility mode, supports setting a variable number of bits for + use in establishing the base address for mmap allocations, has MMU + enabled and provides values for both: + - ARCH_MMAP_RND_COMPAT_BITS_MIN + - ARCH_MMAP_RND_COMPAT_BITS_MAX + +config ARCH_MMAP_RND_COMPAT_BITS_MIN + int + +config ARCH_MMAP_RND_COMPAT_BITS_MAX + int + +config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT + int + +config ARCH_MMAP_RND_COMPAT_BITS + int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT + range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX + default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT + default ARCH_MMAP_RND_COMPAT_BITS_MIN + depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS + help + This value can be used to select the number of bits to use to + determine the random offset to the base address of vma regions + resulting from mmap allocations for compatible applications This + value will be bounded by the architecture's minimum and maximum + supported values. + + This value can be changed after boot using the + /proc/sys/vm/mmap_rnd_compat_bits tunable + source "kernel/gcov/Kconfig" |