1 #ifndef _ASM_X86_UACCESS_H
2 #define _ASM_X86_UACCESS_H
4 * User space memory access functions
6 #include <linux/errno.h>
7 #include <linux/compiler.h>
8 #include <linux/thread_info.h>
9 #include <linux/string.h>
15 #define VERIFY_WRITE 1
18 * The fs value determines whether argument validity checking should be
19 * performed or not. If get_fs() == USER_DS, checking is performed, with
20 * get_fs() == KERNEL_DS, checking is bypassed.
22 * For historical reasons, these macros are grossly misnamed.
25 #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
27 #define KERNEL_DS MAKE_MM_SEG(-1UL)
28 #define USER_DS MAKE_MM_SEG(TASK_SIZE_MAX)
30 #define get_ds() (KERNEL_DS)
31 #define get_fs() (current_thread_info()->addr_limit)
32 #define set_fs(x) (current_thread_info()->addr_limit = (x))
34 #define segment_eq(a, b) ((a).seg == (b).seg)
36 #define user_addr_max() (current_thread_info()->addr_limit.seg)
37 #define __addr_ok(addr) \
38 ((unsigned long __force)(addr) < user_addr_max())
41 * Test whether a block of memory is a valid user space address.
42 * Returns 0 if the range is valid, nonzero otherwise.
44 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
47 * If we have used "sizeof()" for the size,
48 * we know it won't overflow the limit (but
49 * it might overflow the 'addr', so it's
50 * important to subtract the size from the
51 * limit, not add it to the address).
53 if (__builtin_constant_p(size))
54 return unlikely(addr > limit - size);
56 /* Arbitrary sizes? Be careful about overflow */
58 if (unlikely(addr < size))
60 return unlikely(addr > limit);
63 #define __range_not_ok(addr, size, limit) \
65 __chk_user_ptr(addr); \
66 __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
70 * access_ok: - Checks if a user space pointer is valid
71 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that
72 * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
73 * to write to a block, it is always safe to read from it.
74 * @addr: User space pointer to start of block to check
75 * @size: Size of block to check
77 * Context: User context only. This function may sleep if pagefaults are
80 * Checks if a pointer to a block of memory in user space is valid.
82 * Returns true (nonzero) if the memory block may be valid, false (zero)
83 * if it is definitely invalid.
85 * Note that, depending on architecture, this function probably just
86 * checks that the pointer is in the user space range - after calling
87 * this function, memory access functions may still return -EFAULT.
89 #define access_ok(type, addr, size) \
90 likely(!__range_not_ok(addr, size, user_addr_max()))
93 * The exception table consists of pairs of addresses relative to the
94 * exception table enty itself: the first is the address of an
95 * instruction that is allowed to fault, and the second is the address
96 * at which the program should continue. No registers are modified,
97 * so it is entirely up to the continuation code to figure out what to
100 * All the routines below use bits of fixup code that are out of line
101 * with the main instruction path. This means when everything is well,
102 * we don't even have to jump over them. Further, they do not intrude
103 * on our cache or tlb entries.
106 struct exception_table_entry {
109 /* This is not the generic standard exception_table_entry format */
110 #define ARCH_HAS_SORT_EXTABLE
111 #define ARCH_HAS_SEARCH_EXTABLE
113 extern int fixup_exception(struct pt_regs *regs);
114 extern int early_fixup_exception(unsigned long *ip);
117 * These are the main single-value transfer routines. They automatically
118 * use the right size if we just have the right pointer type.
120 * This gets kind of ugly. We want to return _two_ values in "get_user()"
121 * and yet we don't want to do any pointers, because that is too much
122 * of a performance impact. Thus we have a few rather ugly macros here,
123 * and hide all the ugliness from the user.
125 * The "__xxx" versions of the user access functions are versions that
126 * do not verify the address space, that must have been done previously
127 * with a separate "access_ok()" call (this is used when we do multiple
128 * accesses to the same area of user memory).
131 extern int __get_user_1(void);
132 extern int __get_user_2(void);
133 extern int __get_user_4(void);
134 extern int __get_user_8(void);
135 extern int __get_user_bad(void);
137 #define __uaccess_begin() stac()
138 #define __uaccess_end() clac()
141 * This is a type: either unsigned long, if the argument fits into
142 * that type, or otherwise unsigned long long.
144 #define __inttype(x) \
145 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
148 * get_user: - Get a simple variable from user space.
149 * @x: Variable to store result.
150 * @ptr: Source address, in user space.
152 * Context: User context only. This function may sleep if pagefaults are
155 * This macro copies a single simple variable from user space to kernel
156 * space. It supports simple types like char and int, but not larger
157 * data types like structures or arrays.
159 * @ptr must have pointer-to-simple-variable type, and the result of
160 * dereferencing @ptr must be assignable to @x without a cast.
162 * Returns zero on success, or -EFAULT on error.
163 * On error, the variable @x is set to zero.
166 * Careful: we have to cast the result to the type of the pointer
169 * The use of _ASM_DX as the register specifier is a bit of a
170 * simplification, as gcc only cares about it as the starting point
171 * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
172 * (%ecx being the next register in gcc's x86 register sequence), and
175 * Clang/LLVM cares about the size of the register, but still wants
176 * the base register for something that ends up being a pair.
178 #define get_user(x, ptr) \
181 register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \
182 __chk_user_ptr(ptr); \
184 asm volatile("call __get_user_%P3" \
185 : "=a" (__ret_gu), "=r" (__val_gu) \
186 : "0" (ptr), "i" (sizeof(*(ptr)))); \
187 (x) = (__force __typeof__(*(ptr))) __val_gu; \
188 __builtin_expect(__ret_gu, 0); \
191 #define __put_user_x(size, x, ptr, __ret_pu) \
192 asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
193 : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
198 #define __put_user_asm_u64(x, addr, err, errret) \
200 "1: movl %%eax,0(%2)\n" \
201 "2: movl %%edx,4(%2)\n" \
203 ".section .fixup,\"ax\"\n" \
207 _ASM_EXTABLE(1b, 4b) \
208 _ASM_EXTABLE(2b, 4b) \
210 : "A" (x), "r" (addr), "i" (errret), "0" (err))
212 #define __put_user_asm_ex_u64(x, addr) \
214 "1: movl %%eax,0(%1)\n" \
215 "2: movl %%edx,4(%1)\n" \
217 _ASM_EXTABLE_EX(1b, 2b) \
218 _ASM_EXTABLE_EX(2b, 3b) \
219 : : "A" (x), "r" (addr))
221 #define __put_user_x8(x, ptr, __ret_pu) \
222 asm volatile("call __put_user_8" : "=a" (__ret_pu) \
223 : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
225 #define __put_user_asm_u64(x, ptr, retval, errret) \
226 __put_user_asm(x, ptr, retval, "q", "", "er", errret)
227 #define __put_user_asm_ex_u64(x, addr) \
228 __put_user_asm_ex(x, addr, "q", "", "er")
229 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
232 extern void __put_user_bad(void);
235 * Strange magic calling convention: pointer in %ecx,
236 * value in %eax(:%edx), return value in %eax. clobbers %rbx
238 extern void __put_user_1(void);
239 extern void __put_user_2(void);
240 extern void __put_user_4(void);
241 extern void __put_user_8(void);
244 * put_user: - Write a simple value into user space.
245 * @x: Value to copy to user space.
246 * @ptr: Destination address, in user space.
248 * Context: User context only. This function may sleep if pagefaults are
251 * This macro copies a single simple value from kernel space to user
252 * space. It supports simple types like char and int, but not larger
253 * data types like structures or arrays.
255 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
256 * to the result of dereferencing @ptr.
258 * Returns zero on success, or -EFAULT on error.
260 #define put_user(x, ptr) \
263 __typeof__(*(ptr)) __pu_val; \
264 __chk_user_ptr(ptr); \
267 switch (sizeof(*(ptr))) { \
269 __put_user_x(1, __pu_val, ptr, __ret_pu); \
272 __put_user_x(2, __pu_val, ptr, __ret_pu); \
275 __put_user_x(4, __pu_val, ptr, __ret_pu); \
278 __put_user_x8(__pu_val, ptr, __ret_pu); \
281 __put_user_x(X, __pu_val, ptr, __ret_pu); \
284 __builtin_expect(__ret_pu, 0); \
287 #define __put_user_size(x, ptr, size, retval, errret) \
290 __chk_user_ptr(ptr); \
293 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
296 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
299 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
302 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval, \
311 * This doesn't do __uaccess_begin/end - the exception handling
312 * around it must do that.
314 #define __put_user_size_ex(x, ptr, size) \
316 __chk_user_ptr(ptr); \
319 __put_user_asm_ex(x, ptr, "b", "b", "iq"); \
322 __put_user_asm_ex(x, ptr, "w", "w", "ir"); \
325 __put_user_asm_ex(x, ptr, "l", "k", "ir"); \
328 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr); \
336 #define __get_user_asm_u64(x, ptr, retval, errret) (x) = __get_user_bad()
337 #define __get_user_asm_ex_u64(x, ptr) (x) = __get_user_bad()
339 #define __get_user_asm_u64(x, ptr, retval, errret) \
340 __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
341 #define __get_user_asm_ex_u64(x, ptr) \
342 __get_user_asm_ex(x, ptr, "q", "", "=r")
345 #define __get_user_size(x, ptr, size, retval, errret) \
348 __chk_user_ptr(ptr); \
351 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
354 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
357 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
360 __get_user_asm_u64(x, ptr, retval, errret); \
363 (x) = __get_user_bad(); \
367 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret) \
369 "1: mov"itype" %2,%"rtype"1\n" \
371 ".section .fixup,\"ax\"\n" \
373 " xor"itype" %"rtype"1,%"rtype"1\n" \
376 _ASM_EXTABLE(1b, 3b) \
377 : "=r" (err), ltype(x) \
378 : "m" (__m(addr)), "i" (errret), "0" (err))
381 * This doesn't do __uaccess_begin/end - the exception handling
382 * around it must do that.
384 #define __get_user_size_ex(x, ptr, size) \
386 __chk_user_ptr(ptr); \
389 __get_user_asm_ex(x, ptr, "b", "b", "=q"); \
392 __get_user_asm_ex(x, ptr, "w", "w", "=r"); \
395 __get_user_asm_ex(x, ptr, "l", "k", "=r"); \
398 __get_user_asm_ex_u64(x, ptr); \
401 (x) = __get_user_bad(); \
405 #define __get_user_asm_ex(x, addr, itype, rtype, ltype) \
406 asm volatile("1: mov"itype" %1,%"rtype"0\n" \
408 _ASM_EXTABLE_EX(1b, 2b) \
409 : ltype(x) : "m" (__m(addr)))
411 #define __put_user_nocheck(x, ptr, size) \
415 __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
417 __builtin_expect(__pu_err, 0); \
420 #define __get_user_nocheck(x, ptr, size) \
423 unsigned long __gu_val; \
425 __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \
427 (x) = (__force __typeof__(*(ptr)))__gu_val; \
428 __builtin_expect(__gu_err, 0); \
431 /* FIXME: this hack is definitely wrong -AK */
432 struct __large_struct { unsigned long buf[100]; };
433 #define __m(x) (*(struct __large_struct __user *)(x))
436 * Tell gcc we read from memory instead of writing: this is because
437 * we do not write to any memory gcc knows about, so there are no
440 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret) \
442 "1: mov"itype" %"rtype"1,%2\n" \
444 ".section .fixup,\"ax\"\n" \
448 _ASM_EXTABLE(1b, 3b) \
450 : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
452 #define __put_user_asm_ex(x, addr, itype, rtype, ltype) \
453 asm volatile("1: mov"itype" %"rtype"0,%1\n" \
455 _ASM_EXTABLE_EX(1b, 2b) \
456 : : ltype(x), "m" (__m(addr)))
459 * uaccess_try and catch
461 #define uaccess_try do { \
462 current_thread_info()->uaccess_err = 0; \
466 #define uaccess_catch(err) \
468 (err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0); \
472 * __get_user: - Get a simple variable from user space, with less checking.
473 * @x: Variable to store result.
474 * @ptr: Source address, in user space.
476 * Context: User context only. This function may sleep if pagefaults are
479 * This macro copies a single simple variable from user space to kernel
480 * space. It supports simple types like char and int, but not larger
481 * data types like structures or arrays.
483 * @ptr must have pointer-to-simple-variable type, and the result of
484 * dereferencing @ptr must be assignable to @x without a cast.
486 * Caller must check the pointer with access_ok() before calling this
489 * Returns zero on success, or -EFAULT on error.
490 * On error, the variable @x is set to zero.
493 #define __get_user(x, ptr) \
494 __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
497 * __put_user: - Write a simple value into user space, with less checking.
498 * @x: Value to copy to user space.
499 * @ptr: Destination address, in user space.
501 * Context: User context only. This function may sleep if pagefaults are
504 * This macro copies a single simple value from kernel space to user
505 * space. It supports simple types like char and int, but not larger
506 * data types like structures or arrays.
508 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
509 * to the result of dereferencing @ptr.
511 * Caller must check the pointer with access_ok() before calling this
514 * Returns zero on success, or -EFAULT on error.
517 #define __put_user(x, ptr) \
518 __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
520 #define __get_user_unaligned __get_user
521 #define __put_user_unaligned __put_user
524 * {get|put}_user_try and catch
528 * } get_user_catch(err)
530 #define get_user_try uaccess_try
531 #define get_user_catch(err) uaccess_catch(err)
533 #define get_user_ex(x, ptr) do { \
534 unsigned long __gue_val; \
535 __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr)))); \
536 (x) = (__force __typeof__(*(ptr)))__gue_val; \
539 #define put_user_try uaccess_try
540 #define put_user_catch(err) uaccess_catch(err)
542 #define put_user_ex(x, ptr) \
543 __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
546 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
547 extern __must_check long
548 strncpy_from_user(char *dst, const char __user *src, long count);
550 extern __must_check long strlen_user(const char __user *str);
551 extern __must_check long strnlen_user(const char __user *str, long n);
553 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
554 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
556 extern void __cmpxchg_wrong_size(void)
557 __compiletime_error("Bad argument size for cmpxchg");
559 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size) \
562 __typeof__(ptr) __uval = (uval); \
563 __typeof__(*(ptr)) __old = (old); \
564 __typeof__(*(ptr)) __new = (new); \
570 "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n" \
572 "\t.section .fixup, \"ax\"\n" \
576 _ASM_EXTABLE(1b, 3b) \
577 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
578 : "i" (-EFAULT), "q" (__new), "1" (__old) \
586 "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n" \
588 "\t.section .fixup, \"ax\"\n" \
592 _ASM_EXTABLE(1b, 3b) \
593 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
594 : "i" (-EFAULT), "r" (__new), "1" (__old) \
602 "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n" \
604 "\t.section .fixup, \"ax\"\n" \
608 _ASM_EXTABLE(1b, 3b) \
609 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
610 : "i" (-EFAULT), "r" (__new), "1" (__old) \
617 if (!IS_ENABLED(CONFIG_X86_64)) \
618 __cmpxchg_wrong_size(); \
621 "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n" \
623 "\t.section .fixup, \"ax\"\n" \
627 _ASM_EXTABLE(1b, 3b) \
628 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
629 : "i" (-EFAULT), "r" (__new), "1" (__old) \
635 __cmpxchg_wrong_size(); \
642 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new) \
644 access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ? \
645 __user_atomic_cmpxchg_inatomic((uval), (ptr), \
646 (old), (new), sizeof(*(ptr))) : \
651 * movsl can be slow when source and dest are not both 8-byte aligned
653 #ifdef CONFIG_X86_INTEL_USERCOPY
654 extern struct movsl_mask {
656 } ____cacheline_aligned_in_smp movsl_mask;
659 #define ARCH_HAS_NOCACHE_UACCESS 1
662 # include <asm/uaccess_32.h>
664 # include <asm/uaccess_64.h>
667 unsigned long __must_check _copy_from_user(void *to, const void __user *from,
669 unsigned long __must_check _copy_to_user(void __user *to, const void *from,
672 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
673 # define copy_user_diag __compiletime_error
675 # define copy_user_diag __compiletime_warning
678 extern void copy_user_diag("copy_from_user() buffer size is too small")
679 copy_from_user_overflow(void);
680 extern void copy_user_diag("copy_to_user() buffer size is too small")
681 copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
683 #undef copy_user_diag
685 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
688 __compiletime_warning("copy_from_user() buffer size is not provably correct")
689 __copy_from_user_overflow(void) __asm__("copy_from_user_overflow");
690 #define __copy_from_user_overflow(size, count) __copy_from_user_overflow()
693 __compiletime_warning("copy_to_user() buffer size is not provably correct")
694 __copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
695 #define __copy_to_user_overflow(size, count) __copy_to_user_overflow()
700 __copy_from_user_overflow(int size, unsigned long count)
702 WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
705 #define __copy_to_user_overflow __copy_from_user_overflow
709 static __always_inline unsigned long __must_check
710 copy_from_user(void *to, const void __user *from, unsigned long n)
712 int sz = __compiletime_object_size(to);
717 * While we would like to have the compiler do the checking for us
718 * even in the non-constant size case, any false positives there are
719 * a problem (especially when DEBUG_STRICT_USER_COPY_CHECKS, but even
720 * without - the [hopefully] dangerous looking nature of the warning
721 * would make people go look at the respecitive call sites over and
722 * over again just to find that there's no problem).
724 * And there are cases where it's just not realistic for the compiler
725 * to prove the count to be in range. For example when multiple call
726 * sites of a helper function - perhaps in different source files -
727 * all doing proper range checking, yet the helper function not doing
730 * Therefore limit the compile time checking to the constant size
731 * case, and do only runtime checking for non-constant sizes.
734 if (likely(sz < 0 || sz >= n)) {
735 check_object_size(to, n, false);
736 n = _copy_from_user(to, from, n);
737 } else if (__builtin_constant_p(n))
738 copy_from_user_overflow();
740 __copy_from_user_overflow(sz, n);
745 static __always_inline unsigned long __must_check
746 copy_to_user(void __user *to, const void *from, unsigned long n)
748 int sz = __compiletime_object_size(from);
752 /* See the comment in copy_from_user() above. */
753 if (likely(sz < 0 || sz >= n)) {
754 check_object_size(from, n, true);
755 n = _copy_to_user(to, from, n);
756 } else if (__builtin_constant_p(n))
757 copy_to_user_overflow();
759 __copy_to_user_overflow(sz, n);
764 #undef __copy_from_user_overflow
765 #undef __copy_to_user_overflow
768 * The "unsafe" user accesses aren't really "unsafe", but the naming
769 * is a big fat warning: you have to not only do the access_ok()
770 * checking before using them, but you have to surround them with the
771 * user_access_begin/end() pair.
773 #define user_access_begin() __uaccess_begin()
774 #define user_access_end() __uaccess_end()
776 #define unsafe_put_user(x, ptr, err_label) \
779 __put_user_size((x), (ptr), sizeof(*(ptr)), __pu_err, -EFAULT); \
780 if (unlikely(__pu_err)) goto err_label; \
783 #define unsafe_get_user(x, ptr, err_label) \
786 unsigned long __gu_val; \
787 __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT); \
788 (x) = (__force __typeof__(*(ptr)))__gu_val; \
789 if (unlikely(__gu_err)) goto err_label; \
792 #endif /* _ASM_X86_UACCESS_H */