* [PATCH] arm64: uaccess: implement unsafe accessors
@ 2018-09-06 11:09 Julien Thierry
2018-09-06 14:01 ` Will Deacon
2018-09-10 15:44 ` Catalin Marinas
0 siblings, 2 replies; 3+ messages in thread
From: Julien Thierry @ 2018-09-06 11:09 UTC (permalink / raw)
To: linux-arm-kernel
Current implementation of get/put_user_unsafe default to get/put_user
which toggle PAN before each access, despite having been told by the caller
that multiple accesses to user memory were about to happen.
Provide implementations for user_access_begin/end to turn PAN off/on and
implement unsafe accessors that assume PAN was already turned off.
Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/include/asm/uaccess.h | 61 ++++++++++++++++++++++++++++++----------
1 file changed, 46 insertions(+), 15 deletions(-)
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index e66b0fc..c4528dd 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -277,11 +277,9 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
: "+r" (err), "=&r" (x) \
: "r" (addr), "i" (-EFAULT))
-#define __get_user_err(x, ptr, err) \
+#define __get_user_err_unsafe(x, ptr, err) \
do { \
unsigned long __gu_val; \
- __chk_user_ptr(ptr); \
- uaccess_enable_not_uao(); \
switch (sizeof(*(ptr))) { \
case 1: \
__get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr), \
@@ -302,17 +300,24 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
default: \
BUILD_BUG(); \
} \
- uaccess_disable_not_uao(); \
(x) = (__force __typeof__(*(ptr)))__gu_val; \
} while (0)
-#define __get_user_check(x, ptr, err) \
+#define __get_user_err_check(x, ptr, err) \
+do { \
+ __chk_user_ptr(ptr); \
+ uaccess_enable_not_uao(); \
+ __get_user_err_unsafe((x), (ptr), (err)); \
+ uaccess_disable_not_uao(); \
+} while (0)
+
+#define __get_user_err(x, ptr, err, accessor) \
({ \
__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)); \
+ accessor((x), __p, (err)); \
} else { \
(x) = 0; (err) = -EFAULT; \
} \
@@ -320,14 +325,14 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
#define __get_user_error(x, ptr, err) \
({ \
- __get_user_check((x), (ptr), (err)); \
+ __get_user_err((x), (ptr), (err), __get_user_err_check); \
(void)0; \
})
#define __get_user(x, ptr) \
({ \
int __gu_err = 0; \
- __get_user_check((x), (ptr), __gu_err); \
+ __get_user_err((x), (ptr), __gu_err, __get_user_err_check); \
__gu_err; \
})
@@ -347,11 +352,9 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
: "+r" (err) \
: "r" (x), "r" (addr), "i" (-EFAULT))
-#define __put_user_err(x, ptr, err) \
+#define __put_user_err_unsafe(x, ptr, err) \
do { \
__typeof__(*(ptr)) __pu_val = (x); \
- __chk_user_ptr(ptr); \
- uaccess_enable_not_uao(); \
switch (sizeof(*(ptr))) { \
case 1: \
__put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr), \
@@ -372,16 +375,24 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
default: \
BUILD_BUG(); \
} \
+} while (0)
+
+
+#define __put_user_err_check(x, ptr, err) \
+do { \
+ __chk_user_ptr(ptr); \
+ uaccess_enable_not_uao(); \
+ __put_user_err_unsafe((x), (ptr), (err)); \
uaccess_disable_not_uao(); \
} while (0)
-#define __put_user_check(x, ptr, err) \
+#define __put_user_err(x, ptr, err, accessor) \
({ \
__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)); \
+ accessor((x), __p, (err)); \
} else { \
(err) = -EFAULT; \
} \
@@ -389,19 +400,39 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
#define __put_user_error(x, ptr, err) \
({ \
- __put_user_check((x), (ptr), (err)); \
+ __put_user_err((x), (ptr), (err), __put_user_err_check); \
(void)0; \
})
#define __put_user(x, ptr) \
({ \
int __pu_err = 0; \
- __put_user_check((x), (ptr), __pu_err); \
+ __put_user_err((x), (ptr), __pu_err, __put_user_err_check); \
__pu_err; \
})
#define put_user __put_user
+
+#define user_access_begin() uaccess_enable_not_uao()
+#define user_access_end() uaccess_disable_not_uao()
+
+#define unsafe_get_user(x, ptr, err) \
+do { \
+ int __gu_err = 0; \
+ __get_user_err((x), (ptr), __gu_err, __get_user_err_unsafe); \
+ if (__gu_err != 0) \
+ goto err; \
+} while (0)
+
+#define unsafe_put_user(x, ptr, err) \
+do { \
+ int __pu_err = 0; \
+ __put_user_err((x), (ptr), __pu_err, __put_user_err_unsafe); \
+ if (__pu_err != 0) \
+ goto err; \
+} while (0)
+
extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n);
#define raw_copy_from_user(to, from, n) \
({ \
--
1.9.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH] arm64: uaccess: implement unsafe accessors
2018-09-06 11:09 [PATCH] arm64: uaccess: implement unsafe accessors Julien Thierry
@ 2018-09-06 14:01 ` Will Deacon
2018-09-10 15:44 ` Catalin Marinas
1 sibling, 0 replies; 3+ messages in thread
From: Will Deacon @ 2018-09-06 14:01 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, Sep 06, 2018 at 12:09:56PM +0100, Julien Thierry wrote:
> Current implementation of get/put_user_unsafe default to get/put_user
> which toggle PAN before each access, despite having been told by the caller
> that multiple accesses to user memory were about to happen.
>
> Provide implementations for user_access_begin/end to turn PAN off/on and
> implement unsafe accessors that assume PAN was already turned off.
>
> Signed-off-by: Julien Thierry <julien.thierry@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> ---
> arch/arm64/include/asm/uaccess.h | 61 ++++++++++++++++++++++++++++++----------
> 1 file changed, 46 insertions(+), 15 deletions(-)
Tested-by: Will Deacon <will.deacon@arm.com>
Cheers,
Will
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH] arm64: uaccess: implement unsafe accessors
2018-09-06 11:09 [PATCH] arm64: uaccess: implement unsafe accessors Julien Thierry
2018-09-06 14:01 ` Will Deacon
@ 2018-09-10 15:44 ` Catalin Marinas
1 sibling, 0 replies; 3+ messages in thread
From: Catalin Marinas @ 2018-09-10 15:44 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, Sep 06, 2018 at 12:09:56PM +0100, Julien Thierry wrote:
> Current implementation of get/put_user_unsafe default to get/put_user
> which toggle PAN before each access, despite having been told by the caller
> that multiple accesses to user memory were about to happen.
>
> Provide implementations for user_access_begin/end to turn PAN off/on and
> implement unsafe accessors that assume PAN was already turned off.
>
> Signed-off-by: Julien Thierry <julien.thierry@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> ---
> arch/arm64/include/asm/uaccess.h | 61 ++++++++++++++++++++++++++++++----------
> 1 file changed, 46 insertions(+), 15 deletions(-)
Queued for 4.19. Thanks.
--
Catalin
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2018-09-10 15:44 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-09-06 11:09 [PATCH] arm64: uaccess: implement unsafe accessors Julien Thierry
2018-09-06 14:01 ` Will Deacon
2018-09-10 15:44 ` Catalin Marinas
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.