This is a note to let you know that I've just added the patch titled
[Variant 1/Spectre-v1] arm64: uaccess: Don't bother eliding access_ok checks in __{get, put}_user
to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-uaccess-don-t-bother-eliding-access_ok-checks-in-__-get-put-_user.patch
and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Tue Feb 13 17:25:10 CET 2018
From: Will Deacon <will.deacon@xxxxxxx>
Date: Mon, 5 Feb 2018 15:34:22 +0000
Subject: [Variant 1/Spectre-v1] arm64: uaccess: Don't bother eliding access_ok checks in __{get, put}_user
From: Will Deacon <will.deacon@xxxxxxx>
Commit 84624087dd7e upstream.
access_ok isn't an expensive operation once the addr_limit for the current
thread has been loaded into the cache. Given that the initial access_ok
check preceding a sequence of __{get,put}_user operations will take
the brunt of the miss, we can make the __* variants identical to the
full-fat versions, which brings with it the benefits of address masking.
The likely cost in these sequences will be from toggling PAN/UAO, which
we can address later by implementing the *_unsafe versions.
Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/include/asm/uaccess.h | 54 +++++++++++++++++++++++----------------
1 file changed, 32 insertions(+), 22 deletions(-)
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -294,28 +294,33 @@ do { \
(x) = (__force __typeof__(*(ptr)))__gu_val; \
} while (0)
-#define __get_user(x, ptr) \
+#define __get_user_check(x, ptr, err) \
({ \
- int __gu_err = 0; \
- __get_user_err((x), (ptr), __gu_err); \
- __gu_err; \
+ __typeof__(*(ptr)) __user *__p = (ptr); \
+ might_fault(); \
+ if (access_ok(VERIFY_READ, __p, sizeof(*__p))) { \
+ __p = uaccess_mask_ptr(__p); \
+ __get_user_err((x), __p, (err)); \
+ } else { \
+ (x) = 0; (err) = -EFAULT; \
+ } \
})
#define __get_user_error(x, ptr, err) \
({ \
- __get_user_err((x), (ptr), (err)); \
+ __get_user_check((x), (ptr), (err)); \
(void)0; \
})
-#define get_user(x, ptr) \
+#define __get_user(x, ptr) \
({ \
- __typeof__(*(ptr)) __user *__p = (ptr); \
- might_fault(); \
- access_ok(VERIFY_READ, __p, sizeof(*__p)) ? \
- __p = uaccess_mask_ptr(__p), __get_user((x), __p) : \
- ((x) = 0, -EFAULT); \
+ int __gu_err = 0; \
+ __get_user_check((x), (ptr), __gu_err); \
+ __gu_err; \
})
+#define get_user __get_user
+
#define __put_user_asm(instr, alt_instr, reg, x, addr, err, feature) \
asm volatile( \
"1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \
@@ -358,28 +363,33 @@ do { \
uaccess_disable_not_uao(); \
} while (0)
-#define __put_user(x, ptr) \
+#define __put_user_check(x, ptr, err) \
({ \
- int __pu_err = 0; \
- __put_user_err((x), (ptr), __pu_err); \
- __pu_err; \
+ __typeof__(*(ptr)) __user *__p = (ptr); \
+ might_fault(); \
+ if (access_ok(VERIFY_WRITE, __p, sizeof(*__p))) { \
+ __p = uaccess_mask_ptr(__p); \
+ __put_user_err((x), __p, (err)); \
+ } else { \
+ (err) = -EFAULT; \
+ } \
})
#define __put_user_error(x, ptr, err) \
({ \
- __put_user_err((x), (ptr), (err)); \
+ __put_user_check((x), (ptr), (err)); \
(void)0; \
})
-#define put_user(x, ptr) \
+#define __put_user(x, ptr) \
({ \
- __typeof__(*(ptr)) __user *__p = (ptr); \
- might_fault(); \
- access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ? \
- __p = uaccess_mask_ptr(__p), __put_user((x), __p) : \
- -EFAULT; \
+ int __pu_err = 0; \
+ __put_user_check((x), (ptr), __pu_err); \
+ __pu_err; \
})
+#define put_user __put_user
+
extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n);
#define raw_copy_from_user __arch_copy_from_user
extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n);
Patches currently in stable-queue which might be from will.deacon@xxxxxxx are
queue-4.15/arm64-make-user_ds-an-inclusive-limit.patch
queue-4.15/arm64-mm-remove-pre_ttbr0_update_workaround-for-falkor-erratum-e1003.patch
queue-4.15/arm64-uaccess-don-t-bother-eliding-access_ok-checks-in-__-get-put-_user.patch
queue-4.15/arm64-cpufeature-pass-capability-structure-to-enable-callback.patch
queue-4.15/arm64-uaccess-mask-__user-pointers-for-__arch_-clear-copy_-_user.patch
queue-4.15/arm64-mm-add-arm64_kernel_unmapped_at_el0-helper.patch
queue-4.15/arm64-entry-reword-comment-about-post_ttbr_update_workaround.patch
queue-4.15/arm64-kaslr-put-kernel-vectors-address-in-separate-data-page.patch
queue-4.15/arm-arm64-smccc-make-function-identifiers-an-unsigned-quantity.patch
queue-4.15/arm64-move-bp-hardening-to-check_and_switch_context.patch
queue-4.15/arm-arm64-kvm-advertise-smccc-v1.1.patch
queue-4.15/arm64-move-post_ttbr_update_workaround-to-c-code.patch
queue-4.15/arm64-turn-on-kpti-only-on-cpus-that-need-it.patch
queue-4.15/firmware-psci-expose-psci-conduit.patch
queue-4.15/arm64-force-kpti-to-be-disabled-on-cavium-thunderx.patch
queue-4.15/arm64-entry-apply-bp-hardening-for-high-priority-synchronous-exceptions.patch
queue-4.15/arm64-kpti-fix-the-interaction-between-asid-switching-and-software-pan.patch
queue-4.15/firmware-psci-expose-smccc-version-through-psci_ops.patch
queue-4.15/arm64-mm-permit-transitioning-from-global-to-non-global-without-bbm.patch
queue-4.15/arm64-mm-allocate-asids-in-pairs.patch
queue-4.15/arm64-tls-avoid-unconditional-zeroing-of-tpidrro_el0-for-native-tasks.patch
queue-4.15/arm64-use-ret-instruction-for-exiting-the-trampoline.patch
queue-4.15/arm64-futex-mask-__user-pointers-prior-to-dereference.patch
queue-4.15/arm64-entry-explicitly-pass-exception-level-to-kernel_ventry-macro.patch
queue-4.15/arm64-implement-branch-predictor-hardening-for-affected-cortex-a-cpus.patch
queue-4.15/arm64-kpti-make-use-of-ng-dependent-on-arm64_kernel_unmapped_at_el0.patch
queue-4.15/arm-arm64-kvm-add-psci_version-helper.patch
queue-4.15/arm64-kill-psci_get_version-as-a-variant-2-workaround.patch
queue-4.15/arm64-entry-ensure-branch-through-syscall-table-is-bounded-under-speculation.patch
queue-4.15/arm64-mm-use-non-global-mappings-for-kernel-space.patch
queue-4.15/arm64-entry-apply-bp-hardening-for-suspicious-interrupts-from-el0.patch
queue-4.15/arm64-capabilities-handle-duplicate-entries-for-a-capability.patch
queue-4.15/arm64-entry-hook-up-entry-trampoline-to-exception-vectors.patch
queue-4.15/arm64-branch-predictor-hardening-for-cavium-thunderx2.patch
queue-4.15/arm64-uaccess-prevent-speculative-use-of-the-current-addr_limit.patch
queue-4.15/arm64-use-pointer-masking-to-limit-uaccess-speculation.patch
queue-4.15/arm64-add-arm_smccc_arch_workaround_1-bp-hardening-support.patch
queue-4.15/arm64-erratum-work-around-falkor-erratum-e1003-in-trampoline-code.patch
queue-4.15/arm64-mm-fix-and-re-enable-arm64_sw_ttbr0_pan.patch
queue-4.15/arm64-mm-invalidate-both-kernel-and-user-asids-when-performing-tlbi.patch
queue-4.15/drivers-firmware-expose-psci_get_version-through-psci_ops-structure.patch
queue-4.15/arm64-mm-rename-post_ttbr0_update_workaround.patch
queue-4.15/arm64-mm-map-entry-trampoline-into-trampoline-and-kernel-page-tables.patch
queue-4.15/arm-arm64-kvm-turn-kvm_psci_version-into-a-static-inline.patch
queue-4.15/arm-arm64-kvm-implement-psci-1.0-support.patch
queue-4.15/arm64-kconfig-reword-unmap_kernel_at_el0-kconfig-entry.patch
queue-4.15/arm64-mm-move-asid-from-ttbr0-to-ttbr1.patch
queue-4.15/arm64-mm-introduce-ttbr_asid_mask-for-getting-at-the-asid-in-the-ttbr.patch
queue-4.15/arm64-kvm-add-smccc_arch_workaround_1-fast-handling.patch
queue-4.15/arm64-take-into-account-id_aa64pfr0_el1.csv3.patch
queue-4.15/arm64-cputype-add-missing-midr-values-for-cortex-a72-and-cortex-a75.patch
queue-4.15/arm64-kvm-report-smccc_arch_workaround_1-bp-hardening-support.patch
queue-4.15/arm64-barrier-add-csdb-macros-to-control-data-value-prediction.patch
queue-4.15/arm-arm64-smccc-implement-smccc-v1.1-inline-primitive.patch
queue-4.15/perf-arm_spe-fail-device-probe-when-arm64_kernel_unmapped_at_el0.patch
queue-4.15/arm64-implement-branch-predictor-hardening-for-falkor.patch
queue-4.15/arm64-kconfig-add-config_unmap_kernel_at_el0.patch
queue-4.15/arm64-idmap-use-awx-flags-for-.idmap.text-.pushsection-directives.patch
queue-4.15/arm64-run-enable-method-for-errata-work-arounds-on-late-cpus.patch
queue-4.15/arm64-mm-temporarily-disable-arm64_sw_ttbr0_pan.patch
queue-4.15/arm64-entry-add-exception-trampoline-page-for-exceptions-from-el0.patch
queue-4.15/arm64-kvm-make-psci_version-a-fast-path.patch
queue-4.15/arm64-cpufeature-__this_cpu_has_cap-shouldn-t-stop-early.patch
queue-4.15/arm64-implement-array_index_mask_nospec.patch
queue-4.15/arm64-kpti-add-enable-callback-to-remap-swapper-using-ng-mappings.patch
queue-4.15/arm-arm64-kvm-consolidate-the-psci-include-files.patch
queue-4.15/arm64-add-skeleton-to-harden-the-branch-predictor-against-aliasing-attacks.patch
queue-4.15/arm64-cpu_errata-add-kryo-to-falkor-1003-errata.patch
queue-4.15/arm-arm64-kvm-add-smccc-accessors-to-psci-code.patch
queue-4.15/arm64-entry-add-fake-cpu-feature-for-unmapping-the-kernel-at-el0.patch
queue-4.15/arm64-kvm-use-per-cpu-vector-when-bp-hardening-is-enabled.patch
queue-4.15/arm64-cputype-add-midr-values-for-cavium-thunderx2-cpus.patch
queue-4.15/arm64-kvm-increment-pc-after-handling-an-smc-trap.patch