From: Viresh Kumar <viresh.kumar@linaro.org>
To: stable@vger.kernel.org, Julien Thierry <Julien.Thierry@arm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>,
linux-arm-kernel@lists.infradead.org,
Catalin Marinas <catalin.marinas@arm.com>,
Marc Zyngier <marc.zyngier@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Will Deacon <will.deacon@arm.com>,
Russell King <rmk+kernel@arm.linux.org.uk>,
Vincent Guittot <vincent.guittot@linaro.org>,
mark.brown@arm.com
Subject: [PATCH v4.4 V2 05/43] arm64: Use pointer masking to limit uaccess speculation
Date: Fri, 12 Jul 2019 10:57:53 +0530 [thread overview]
Message-ID: <99d86496bf2e822479ec7f26faa6a6d31d4e5524.1562908075.git.viresh.kumar@linaro.org> (raw)
In-Reply-To: <cover.1562908074.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
next prev parent reply other threads:[~2019-07-12 5:29 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-12 5:27 [PATCH v4.4 V2 00/43] V4.4 backport of arm64 Spectre patches Viresh Kumar
2019-07-12 5:27 ` [PATCH v4.4 V2 01/43] arm64: barrier: Add CSDB macros to control data-value prediction Viresh Kumar
2019-07-12 5:27 ` [PATCH v4.4 V2 02/43] arm64: Implement array_index_mask_nospec() Viresh Kumar
2019-07-12 5:27 ` [PATCH v4.4 V2 03/43] arm64: move TASK_* definitions to <asm/processor.h> Viresh Kumar
2019-07-12 5:27 ` [PATCH v4.4 V2 04/43] arm64: Make USER_DS an inclusive limit Viresh Kumar
2019-07-12 5:27 ` Viresh Kumar [this message]
2019-07-12 5:27 ` [PATCH v4.4 V2 06/43] arm64: entry: Ensure branch through syscall table is bounded under speculation Viresh Kumar
2019-07-12 5:27 ` [PATCH v4.4 V2 07/43] arm64: uaccess: Prevent speculative use of the current addr_limit Viresh Kumar
2019-07-12 5:27 ` [PATCH v4.4 V2 08/43] arm64: uaccess: Don't bother eliding access_ok checks in __{get, put}_user Viresh Kumar
2019-07-12 5:27 ` [PATCH v4.4 V2 09/43] mm/kasan: add API to check memory regions Viresh Kumar
2019-07-12 5:27 ` [PATCH v4.4 V2 10/43] arm64: kasan: instrument user memory access API Viresh Kumar
2019-07-12 5:27 ` [PATCH v4.4 V2 11/43] arm64: uaccess: Mask __user pointers for __arch_{clear, copy_*}_user Viresh Kumar
2019-07-31 12:37 ` Mark Rutland
2019-08-01 3:38 ` Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 12/43] arm64: cpufeature: Test 'matches' pointer to find the end of the list Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 13/43] arm64: cpufeature: Add scope for capability check Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 14/43] arm64: Introduce cpu_die_early Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 15/43] arm64: Move cpu_die_early to smp.c Viresh Kumar
2019-07-31 12:35 ` Mark Rutland
2019-08-01 3:35 ` Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 16/43] arm64: Verify CPU errata work arounds on hotplugged CPU Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 17/43] arm64: errata: Calling enable functions for CPU errata too Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 18/43] arm64: Rearrange CPU errata workaround checks Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 19/43] arm64: Run enable method for errata work arounds on late CPUs Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 20/43] arm64: cpufeature: Pass capability structure to ->enable callback Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 21/43] drivers/firmware: Expose psci_get_version through psci_ops structure Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 22/43] arm64: Factor out TTBR0_EL1 post-update workaround into a specific asm macro Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 23/43] arm64: Move post_ttbr_update_workaround to C code Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 24/43] arm64: Add skeleton to harden the branch predictor against aliasing attacks Viresh Kumar
2019-07-31 16:45 ` Mark Rutland
2019-08-01 5:20 ` Viresh Kumar
2019-08-06 12:18 ` Mark Rutland
2019-08-08 12:06 ` Viresh Kumar
2019-08-28 10:23 ` Viresh Kumar
2019-08-28 16:08 ` Mark Rutland
2019-07-12 5:28 ` [PATCH v4.4 V2 25/43] arm64: Move BP hardening to check_and_switch_context Viresh Kumar
2019-07-31 13:09 ` Julien Thierry
2019-08-01 5:09 ` Viresh Kumar
2019-08-01 6:30 ` Julien Thierry
2019-08-01 6:35 ` Viresh Kumar
2019-08-01 6:57 ` Greg KH
2019-08-01 7:05 ` Viresh Kumar
2019-08-01 7:34 ` Will Deacon
2019-08-01 7:41 ` Viresh Kumar
2019-08-01 8:43 ` Greg KH
2019-08-01 8:49 ` Julien Thierry
2019-07-12 5:28 ` [PATCH v4.4 V2 26/43] arm64: entry: Apply BP hardening for high-priority synchronous exceptions Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 27/43] arm64: entry: Apply BP hardening for suspicious interrupts from EL0 Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 28/43] arm64: cputype: Add missing MIDR values for Cortex-A72 and Cortex-A75 Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 29/43] arm64: cpu_errata: Allow an erratum to be match for all revisions of a core Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 30/43] arm64: Implement branch predictor hardening for affected Cortex-A CPUs Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 31/43] arm64: cputype info for Broadcom Vulcan Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 32/43] arm64: cputype: Add MIDR values for Cavium ThunderX2 CPUs Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 33/43] arm64: Branch predictor hardening for Cavium ThunderX2 Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 34/43] ARM: 8478/2: arm/arm64: add arm-smccc Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 35/43] arm/arm64: KVM: Advertise SMCCC v1.1 Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 36/43] arm64: KVM: Report SMCCC_ARCH_WORKAROUND_1 BP hardening support Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 37/43] firmware/psci: Expose PSCI conduit Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 38/43] firmware/psci: Expose SMCCC version through psci_ops Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 39/43] arm/arm64: smccc: Make function identifiers an unsigned quantity Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 40/43] arm/arm64: smccc: Implement SMCCC v1.1 inline primitive Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 41/43] arm64: Add ARM_SMCCC_ARCH_WORKAROUND_1 BP hardening support Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 42/43] arm64: Kill PSCI_GET_VERSION as a variant-2 workaround Viresh Kumar
2019-07-12 5:28 ` [PATCH v4.4 V2 43/43] arm64: futex: Mask __user pointers prior to dereference Viresh Kumar
2019-07-15 13:09 ` [PATCH v4.4 V2 00/43] V4.4 backport of arm64 Spectre patches Mark Rutland
2019-07-16 3:44 ` Viresh Kumar
2019-07-31 2:52 ` Viresh Kumar
2019-07-31 17:02 ` Mark Rutland
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