diff options
| author | Will Deacon <will.deacon@arm.com> | 2018-04-03 12:09:12 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-04-08 12:12:54 +0200 |
| commit | 531a0eb24fb70137714b33956cab71a26d408fcd (patch) | |
| tree | 9497cf85a2bfa1cc3f4400f451c3ad0f36594649 | |
| parent | f6af5324fbda14e56247c60f1fd7d6a50abe32cf (diff) | |
arm64: Kconfig: Add CONFIG_UNMAP_KERNEL_AT_EL0
commit 084eb77cd3a8 upstream.
Add a Kconfig entry to control use of the entry trampoline, which allows
us to unmap the kernel whilst running in userspace and improve the
robustness of KASLR.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Alex Shi <alex.shi@linaro.org> [v4.9 backport]
Signed-off-by: Mark Rutland <mark.rutland@arm.com> [v4.9 backport]
Tested-by: Will Deacon <will.deacon@arm.com>
Tested-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/arm64/Kconfig | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 7769c2e27788..6b6e9f89e40a 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -733,6 +733,19 @@ config FORCE_MAX_ZONEORDER However for 4K, we choose a higher default value, 11 as opposed to 10, giving us 4M allocations matching the default size used by generic code. +config UNMAP_KERNEL_AT_EL0 + bool "Unmap kernel when running in userspace (aka \"KAISER\")" + default y + help + Some attacks against KASLR make use of the timing difference between + a permission fault which could arise from a page table entry that is + present in the TLB, and a translation fault which always requires a + page table walk. This option defends against these attacks by unmapping + the kernel whilst running in userspace, therefore forcing translation + faults for all of kernel space. + + If unsure, say Y. + menuconfig ARMV8_DEPRECATED bool "Emulate deprecated/obsolete ARMv8 instructions" depends on COMPAT |