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| author | Will Deacon | 2017-11-14 15:41:01 +0100 |
|---|---|---|
| committer | Will Deacon | 2017-12-11 14:41:10 +0100 |
| commit | 084eb77cd3a81134d02500977dc0ecc9277dc97d (patch) | |
| tree | 8732ef0b6502c51a5b3be805a7f532df2f5abeeb /arch/arm64/Kconfig | |
| parent | arm64: entry: Add fake CPU feature for unmapping the kernel at EL0 (diff) | |
| download | kernel-qcow2-linux-084eb77cd3a81134d02500977dc0ecc9277dc97d.tar.gz kernel-qcow2-linux-084eb77cd3a81134d02500977dc0ecc9277dc97d.tar.xz kernel-qcow2-linux-084eb77cd3a81134d02500977dc0ecc9277dc97d.zip | |
arm64: Kconfig: Add CONFIG_UNMAP_KERNEL_AT_EL0
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>
Diffstat (limited to 'arch/arm64/Kconfig')
| -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 fdcc7b9bb15d..3af1657fcac3 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -833,6 +833,19 @@ 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 |