mirror of https://gitee.com/openkylin/linux.git
Revert "arm64: uaccess: implement unsafe accessors"
This reverts commit a1f33941f7.
The unsafe accessors allow the PAN enable/disable calls to be made
once for a group of accesses. Adding these means we can now have
sequences that look like this:
| user_access_begin();
| unsafe_put_user(static-value, x, err);
| unsafe_put_user(helper-that-sleeps(), x, err);
| user_access_end();
Calling schedule() without taking an exception doesn't switch the
PSTATE or TTBRs. We can switch out of a uaccess-enabled region, and
run other code with uaccess enabled for a different thread.
We can also switch from uaccess-disabled code back into this region,
meaning the unsafe_put_user()s will fault.
For software-PAN, threads that do this will get stuck as
handle_mm_fault() will determine the page has already been mapped in,
but we fault again as the page tables aren't loaded.
To solve this we need code in __switch_to() that save/restores the
PAN state.
Acked-by: Julien Thierry <julien.thierry@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
James Morse
Catalin Marinas
parent
742fafa50b
commit
3b82a6ea23
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@ -276,9 +276,11 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
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: "+r" (err), "=&r" (x) \
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: "r" (addr), "i" (-EFAULT))
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#define __get_user_err_unsafe(x, ptr, err) \
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#define __get_user_err(x, ptr, err) \
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do { \
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unsigned long __gu_val; \
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__chk_user_ptr(ptr); \
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uaccess_enable_not_uao(); \
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switch (sizeof(*(ptr))) { \
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case 1: \
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__get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr), \
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@ -299,24 +301,17 @@ do { \
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default: \
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BUILD_BUG(); \
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} \
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uaccess_disable_not_uao(); \
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(x) = (__force __typeof__(*(ptr)))__gu_val; \
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} while (0)
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#define __get_user_err_check(x, ptr, err) \
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do { \
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__chk_user_ptr(ptr); \
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uaccess_enable_not_uao(); \
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__get_user_err_unsafe((x), (ptr), (err)); \
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uaccess_disable_not_uao(); \
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} while (0)
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#define __get_user_err(x, ptr, err, accessor) \
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#define __get_user_check(x, ptr, err) \
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({ \
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__typeof__(*(ptr)) __user *__p = (ptr); \
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might_fault(); \
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if (access_ok(VERIFY_READ, __p, sizeof(*__p))) { \
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__p = uaccess_mask_ptr(__p); \
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accessor((x), __p, (err)); \
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__get_user_err((x), __p, (err)); \
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} else { \
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(x) = 0; (err) = -EFAULT; \
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} \
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@ -324,14 +319,14 @@ do { \
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#define __get_user_error(x, ptr, err) \
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({ \
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__get_user_err((x), (ptr), (err), __get_user_err_check); \
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__get_user_check((x), (ptr), (err)); \
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(void)0; \
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})
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#define __get_user(x, ptr) \
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({ \
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int __gu_err = 0; \
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__get_user_err((x), (ptr), __gu_err, __get_user_err_check); \
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__get_user_check((x), (ptr), __gu_err); \
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__gu_err; \
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})
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@ -351,9 +346,11 @@ do { \
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: "+r" (err) \
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: "r" (x), "r" (addr), "i" (-EFAULT))
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#define __put_user_err_unsafe(x, ptr, err) \
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#define __put_user_err(x, ptr, err) \
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do { \
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__typeof__(*(ptr)) __pu_val = (x); \
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__chk_user_ptr(ptr); \
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uaccess_enable_not_uao(); \
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switch (sizeof(*(ptr))) { \
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case 1: \
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__put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr), \
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@ -374,24 +371,16 @@ do { \
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default: \
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BUILD_BUG(); \
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} \
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} while (0)
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#define __put_user_err_check(x, ptr, err) \
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do { \
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__chk_user_ptr(ptr); \
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uaccess_enable_not_uao(); \
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__put_user_err_unsafe((x), (ptr), (err)); \
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uaccess_disable_not_uao(); \
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} while (0)
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#define __put_user_err(x, ptr, err, accessor) \
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#define __put_user_check(x, ptr, err) \
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({ \
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__typeof__(*(ptr)) __user *__p = (ptr); \
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might_fault(); \
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if (access_ok(VERIFY_WRITE, __p, sizeof(*__p))) { \
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__p = uaccess_mask_ptr(__p); \
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accessor((x), __p, (err)); \
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__put_user_err((x), __p, (err)); \
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} else { \
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(err) = -EFAULT; \
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} \
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@ -399,39 +388,19 @@ do { \
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#define __put_user_error(x, ptr, err) \
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({ \
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__put_user_err((x), (ptr), (err), __put_user_err_check); \
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__put_user_check((x), (ptr), (err)); \
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(void)0; \
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})
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#define __put_user(x, ptr) \
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({ \
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int __pu_err = 0; \
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__put_user_err((x), (ptr), __pu_err, __put_user_err_check); \
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__put_user_check((x), (ptr), __pu_err); \
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__pu_err; \
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})
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#define put_user __put_user
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#define user_access_begin() uaccess_enable_not_uao()
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#define user_access_end() uaccess_disable_not_uao()
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#define unsafe_get_user(x, ptr, err) \
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do { \
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int __gu_err = 0; \
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__get_user_err((x), (ptr), __gu_err, __get_user_err_unsafe); \
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if (__gu_err != 0) \
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goto err; \
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} while (0)
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#define unsafe_put_user(x, ptr, err) \
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do { \
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int __pu_err = 0; \
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__put_user_err((x), (ptr), __pu_err, __put_user_err_unsafe); \
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if (__pu_err != 0) \
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goto err; \
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} while (0)
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extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n);
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#define raw_copy_from_user(to, from, n) \
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({ \
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