From: Viresh Kumar <viresh.kumar@linaro.org>
To: linux-arm-kernel@lists.infradead.org,
Julien Thierry <Julien.Thierry@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
Marc Zyngier <marc.zyngier@arm.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Will Deacon <will.deacon@arm.com>,
stable@vger.kernel.org, mark.brown@arm.com,
Catalin Marinas <catalin.marinas@arm.com>,
Russell King <rmk+kernel@arm.linux.org.uk>
Subject: [PATCH v4.4 06/45] arm64: Use pointer masking to limit uaccess speculation
Date: Fri, 14 Jun 2019 08:37:49 +0530 [thread overview]
Message-ID: <33a351b8683ca17c3d6ed3711d2c6fe2ae1a36f3.1560480942.git.viresh.kumar@linaro.org> (raw)
In-Reply-To: <cover.1560480942.git.viresh.kumar@linaro.org>
From: Robin Murphy <robin.murphy@arm.com>
commit 4d8efc2d5ee4c9ccfeb29ee8afd47a8660d0c0ce upstream.
Similarly to x86, mitigate speculation past an access_ok() check by
masking the pointer against the address limit before use.
Even if we don't expect speculative writes per se, it is plausible that
a CPU may still speculate at least as far as fetching a cache line for
writing, hence we also harden put_user() and clear_user() for peace of
mind.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
arch/arm64/include/asm/uaccess.h | 26 +++++++++++++++++++++++---
1 file changed, 23 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index c625cc5531fc..75363d723262 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -121,6 +121,26 @@ static inline unsigned long __range_ok(unsigned long addr, unsigned long size)
#define access_ok(type, addr, size) __range_ok((unsigned long)(addr), size)
#define user_addr_max get_fs
+/*
+ * Sanitise a uaccess pointer such that it becomes NULL if above the
+ * current addr_limit.
+ */
+#define uaccess_mask_ptr(ptr) (__typeof__(ptr))__uaccess_mask_ptr(ptr)
+static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
+{
+ void __user *safe_ptr;
+
+ asm volatile(
+ " bics xzr, %1, %2\n"
+ " csel %0, %1, xzr, eq\n"
+ : "=&r" (safe_ptr)
+ : "r" (ptr), "r" (current_thread_info()->addr_limit)
+ : "cc");
+
+ csdb();
+ return safe_ptr;
+}
+
/*
* The "__xxx" versions of the user access functions do not verify the address
* space - it must have been done previously with a separate "access_ok()"
@@ -193,7 +213,7 @@ do { \
__typeof__(*(ptr)) __user *__p = (ptr); \
might_fault(); \
access_ok(VERIFY_READ, __p, sizeof(*__p)) ? \
- __get_user((x), __p) : \
+ __p = uaccess_mask_ptr(__p), __get_user((x), __p) : \
((x) = 0, -EFAULT); \
})
@@ -259,7 +279,7 @@ do { \
__typeof__(*(ptr)) __user *__p = (ptr); \
might_fault(); \
access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ? \
- __put_user((x), __p) : \
+ __p = uaccess_mask_ptr(__p), __put_user((x), __p) : \
-EFAULT; \
})
@@ -297,7 +317,7 @@ static inline unsigned long __must_check copy_in_user(void __user *to, const voi
static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
{
if (access_ok(VERIFY_WRITE, to, n))
- n = __clear_user(to, n);
+ n = __clear_user(__uaccess_mask_ptr(to), n);
return n;
}
--
2.21.0.rc0.269.g1a574e7a288b
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next prev parent reply other threads:[~2019-06-14 3:14 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-14 3:07 [PATCH v4.4 00/45] V4.4 backport of arm64 Spectre patches Viresh Kumar
2019-06-14 3:07 ` [PATCH v4.4 01/45] arm64: barrier: Add CSDB macros to control data-value prediction Viresh Kumar
2019-06-14 3:07 ` [PATCH v4.4 02/45] arm64: Implement array_index_mask_nospec() Viresh Kumar
2019-06-14 3:07 ` [PATCH v4.4 03/45] arm64: remove duplicate macro __KERNEL__ check Viresh Kumar
2019-06-14 3:07 ` [PATCH v4.4 04/45] arm64: move TASK_* definitions to <asm/processor.h> Viresh Kumar
2019-06-14 3:07 ` [PATCH v4.4 05/45] arm64: Make USER_DS an inclusive limit Viresh Kumar
2019-06-14 3:07 ` Viresh Kumar [this message]
2019-06-14 3:07 ` [PATCH v4.4 07/45] arm64: entry: Ensure branch through syscall table is bounded under speculation Viresh Kumar
2019-06-14 3:07 ` [PATCH v4.4 08/45] arm64: uaccess: Prevent speculative use of the current addr_limit Viresh Kumar
2019-06-14 3:07 ` [PATCH v4.4 09/45] arm64: uaccess: Don't bother eliding access_ok checks in __{get, put}_user Viresh Kumar
2019-06-14 3:07 ` [PATCH v4.4 10/45] mm/kasan: add API to check memory regions Viresh Kumar
2019-07-04 14:15 ` Julien Thierry
2019-07-05 3:13 ` Viresh Kumar
2019-06-14 3:07 ` [PATCH v4.4 11/45] arm64: kasan: instrument user memory access API Viresh Kumar
2019-06-14 3:07 ` [PATCH v4.4 12/45] arm64: uaccess: Mask __user pointers for __arch_{clear, copy_*}_user Viresh Kumar
2019-06-14 3:07 ` [PATCH v4.4 13/45] arm64: cpufeature: Pass capability structure to ->enable callback Viresh Kumar
2019-06-14 3:07 ` [PATCH v4.4 14/45] drivers/firmware: Expose psci_get_version through psci_ops structure Viresh Kumar
2019-06-14 3:07 ` [PATCH v4.4 15/45] arm64: Factor out TTBR0_EL1 post-update workaround into a specific asm macro Viresh Kumar
2019-06-14 3:07 ` [PATCH v4.4 16/45] arm64: Move post_ttbr_update_workaround to C code Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 17/45] arm64: cpufeature: Add scope for capability check Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 18/45] arm64: Add skeleton to harden the branch predictor against aliasing attacks Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 19/45] arm64: Move BP hardening to check_and_switch_context Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 20/45] mm: Introduce lm_alias Viresh Kumar
2019-06-17 12:33 ` Julien Thierry
2019-06-18 5:00 ` Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 21/45] arm64: entry: Apply BP hardening for high-priority synchronous exceptions Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 22/45] arm64: entry: Apply BP hardening for suspicious interrupts from EL0 Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 23/45] arm64: cputype: Add missing MIDR values for Cortex-A72 and Cortex-A75 Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 24/45] arm64: cpu_errata: Allow an erratum to be match for all revisions of a core Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 25/45] arm64: Implement branch predictor hardening for affected Cortex-A CPUs Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 26/45] arm64: cputype info for Broadcom Vulcan Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 27/45] arm64: cputype: Add MIDR values for Cavium ThunderX2 CPUs Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 28/45] arm64: Branch predictor hardening for Cavium ThunderX2 Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 29/45] arm64: KVM: Increment PC after handling an SMC trap Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 30/45] arm/arm64: KVM: Consolidate the PSCI include files Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 31/45] arm/arm64: KVM: Add PSCI_VERSION helper Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 32/45] arm/arm64: KVM: Add smccc accessors to PSCI code Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 33/45] ARM: 8478/2: arm/arm64: add arm-smccc Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 34/45] arm/arm64: KVM: Implement PSCI 1.0 support Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 35/45] arm/arm64: KVM: Advertise SMCCC v1.1 Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 36/45] arm/arm64: KVM: Turn kvm_psci_version into a static inline Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 37/45] arm64: KVM: Report SMCCC_ARCH_WORKAROUND_1 BP hardening support Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 38/45] arm64: KVM: Add SMCCC_ARCH_WORKAROUND_1 fast handling Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 39/45] firmware/psci: Expose PSCI conduit Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 40/45] firmware/psci: Expose SMCCC version through psci_ops Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 41/45] arm/arm64: smccc: Make function identifiers an unsigned quantity Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 42/45] arm/arm64: smccc: Implement SMCCC v1.1 inline primitive Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 43/45] arm64: Add ARM_SMCCC_ARCH_WORKAROUND_1 BP hardening support Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 44/45] arm64: Kill PSCI_GET_VERSION as a variant-2 workaround Viresh Kumar
2019-06-14 3:08 ` [PATCH v4.4 45/45] arm64: futex: Mask __user pointers prior to dereference Viresh Kumar
2019-06-17 12:10 ` [PATCH v4.4 00/45] V4.4 backport of arm64 Spectre patches Greg KH
2019-06-17 16:03 ` Julien Thierry
2019-06-18 10:21 ` Viresh Kumar
2019-06-19 11:03 ` Julien Thierry
2019-06-19 11:20 ` Viresh Kumar
2019-06-17 16:30 ` Julien Thierry
2019-07-11 13:57 ` Julien Thierry
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