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/kasan-checks.h>
9 #include <linux/thread_info.h>
10 #include <linux/string.h>
14 #include <asm/extable.h>
17 #define VERIFY_WRITE 1
20 * The fs value determines whether argument validity checking should be
21 * performed or not. If get_fs() == USER_DS, checking is performed, with
22 * get_fs() == KERNEL_DS, checking is bypassed.
24 * For historical reasons, these macros are grossly misnamed.
27 #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
29 #define KERNEL_DS MAKE_MM_SEG(-1UL)
30 #define USER_DS MAKE_MM_SEG(TASK_SIZE_MAX)
32 #define get_ds() (KERNEL_DS)
33 #define get_fs() (current->thread.addr_limit)
34 #define set_fs(x) (current->thread.addr_limit = (x))
36 #define segment_eq(a, b) ((a).seg == (b).seg)
38 #define user_addr_max() (current->thread.addr_limit.seg)
39 #define __addr_ok(addr) \
40 ((unsigned long __force)(addr) < user_addr_max())
43 * Test whether a block of memory is a valid user space address.
44 * Returns 0 if the range is valid, nonzero otherwise.
46 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
49 * If we have used "sizeof()" for the size,
50 * we know it won't overflow the limit (but
51 * it might overflow the 'addr', so it's
52 * important to subtract the size from the
53 * limit, not add it to the address).
55 if (__builtin_constant_p(size))
56 return unlikely(addr > limit - size);
58 /* Arbitrary sizes? Be careful about overflow */
60 if (unlikely(addr < size))
62 return unlikely(addr > limit);
65 #define __range_not_ok(addr, size, limit) \
67 __chk_user_ptr(addr); \
68 __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
72 * access_ok: - Checks if a user space pointer is valid
73 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that
74 * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
75 * to write to a block, it is always safe to read from it.
76 * @addr: User space pointer to start of block to check
77 * @size: Size of block to check
79 * Context: User context only. This function may sleep if pagefaults are
82 * Checks if a pointer to a block of memory in user space is valid.
84 * Returns true (nonzero) if the memory block may be valid, false (zero)
85 * if it is definitely invalid.
87 * Note that, depending on architecture, this function probably just
88 * checks that the pointer is in the user space range - after calling
89 * this function, memory access functions may still return -EFAULT.
91 #define access_ok(type, addr, size) \
92 likely(!__range_not_ok(addr, size, user_addr_max()))
95 * These are the main single-value transfer routines. They automatically
96 * use the right size if we just have the right pointer type.
98 * This gets kind of ugly. We want to return _two_ values in "get_user()"
99 * and yet we don't want to do any pointers, because that is too much
100 * of a performance impact. Thus we have a few rather ugly macros here,
101 * and hide all the ugliness from the user.
103 * The "__xxx" versions of the user access functions are versions that
104 * do not verify the address space, that must have been done previously
105 * with a separate "access_ok()" call (this is used when we do multiple
106 * accesses to the same area of user memory).
109 extern int __get_user_1(void);
110 extern int __get_user_2(void);
111 extern int __get_user_4(void);
112 extern int __get_user_8(void);
113 extern int __get_user_bad(void);
115 #define __uaccess_begin() stac()
116 #define __uaccess_end() clac()
119 * This is a type: either unsigned long, if the argument fits into
120 * that type, or otherwise unsigned long long.
122 #define __inttype(x) \
123 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
126 * get_user: - Get a simple variable from user space.
127 * @x: Variable to store result.
128 * @ptr: Source address, in user space.
130 * Context: User context only. This function may sleep if pagefaults are
133 * This macro copies a single simple variable from user space to kernel
134 * space. It supports simple types like char and int, but not larger
135 * data types like structures or arrays.
137 * @ptr must have pointer-to-simple-variable type, and the result of
138 * dereferencing @ptr must be assignable to @x without a cast.
140 * Returns zero on success, or -EFAULT on error.
141 * On error, the variable @x is set to zero.
144 * Careful: we have to cast the result to the type of the pointer
147 * The use of _ASM_DX as the register specifier is a bit of a
148 * simplification, as gcc only cares about it as the starting point
149 * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
150 * (%ecx being the next register in gcc's x86 register sequence), and
153 * Clang/LLVM cares about the size of the register, but still wants
154 * the base register for something that ends up being a pair.
156 #define get_user(x, ptr) \
159 register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \
160 register void *__sp asm(_ASM_SP); \
161 __chk_user_ptr(ptr); \
163 asm volatile("call __get_user_%P4" \
164 : "=a" (__ret_gu), "=r" (__val_gu), "+r" (__sp) \
165 : "0" (ptr), "i" (sizeof(*(ptr)))); \
166 (x) = (__force __typeof__(*(ptr))) __val_gu; \
167 __builtin_expect(__ret_gu, 0); \
170 #define __put_user_x(size, x, ptr, __ret_pu) \
171 asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
172 : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
177 #define __put_user_asm_u64(x, addr, err, errret) \
179 "1: movl %%eax,0(%2)\n" \
180 "2: movl %%edx,4(%2)\n" \
182 ".section .fixup,\"ax\"\n" \
186 _ASM_EXTABLE(1b, 4b) \
187 _ASM_EXTABLE(2b, 4b) \
189 : "A" (x), "r" (addr), "i" (errret), "0" (err))
191 #define __put_user_asm_ex_u64(x, addr) \
193 "1: movl %%eax,0(%1)\n" \
194 "2: movl %%edx,4(%1)\n" \
196 _ASM_EXTABLE_EX(1b, 2b) \
197 _ASM_EXTABLE_EX(2b, 3b) \
198 : : "A" (x), "r" (addr))
200 #define __put_user_x8(x, ptr, __ret_pu) \
201 asm volatile("call __put_user_8" : "=a" (__ret_pu) \
202 : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
204 #define __put_user_asm_u64(x, ptr, retval, errret) \
205 __put_user_asm(x, ptr, retval, "q", "", "er", errret)
206 #define __put_user_asm_ex_u64(x, addr) \
207 __put_user_asm_ex(x, addr, "q", "", "er")
208 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
211 extern void __put_user_bad(void);
214 * Strange magic calling convention: pointer in %ecx,
215 * value in %eax(:%edx), return value in %eax. clobbers %rbx
217 extern void __put_user_1(void);
218 extern void __put_user_2(void);
219 extern void __put_user_4(void);
220 extern void __put_user_8(void);
223 * put_user: - Write a simple value into user space.
224 * @x: Value to copy to user space.
225 * @ptr: Destination address, in user space.
227 * Context: User context only. This function may sleep if pagefaults are
230 * This macro copies a single simple value from kernel space to user
231 * space. It supports simple types like char and int, but not larger
232 * data types like structures or arrays.
234 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
235 * to the result of dereferencing @ptr.
237 * Returns zero on success, or -EFAULT on error.
239 #define put_user(x, ptr) \
242 __typeof__(*(ptr)) __pu_val; \
243 __chk_user_ptr(ptr); \
246 switch (sizeof(*(ptr))) { \
248 __put_user_x(1, __pu_val, ptr, __ret_pu); \
251 __put_user_x(2, __pu_val, ptr, __ret_pu); \
254 __put_user_x(4, __pu_val, ptr, __ret_pu); \
257 __put_user_x8(__pu_val, ptr, __ret_pu); \
260 __put_user_x(X, __pu_val, ptr, __ret_pu); \
263 __builtin_expect(__ret_pu, 0); \
266 #define __put_user_size(x, ptr, size, retval, errret) \
269 __chk_user_ptr(ptr); \
272 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
275 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
278 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
281 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval, \
290 * This doesn't do __uaccess_begin/end - the exception handling
291 * around it must do that.
293 #define __put_user_size_ex(x, ptr, size) \
295 __chk_user_ptr(ptr); \
298 __put_user_asm_ex(x, ptr, "b", "b", "iq"); \
301 __put_user_asm_ex(x, ptr, "w", "w", "ir"); \
304 __put_user_asm_ex(x, ptr, "l", "k", "ir"); \
307 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr); \
315 #define __get_user_asm_u64(x, ptr, retval, errret) \
317 __typeof__(ptr) __ptr = (ptr); \
318 asm volatile(ASM_STAC "\n" \
319 "1: movl %2,%%eax\n" \
320 "2: movl %3,%%edx\n" \
321 "3: " ASM_CLAC "\n" \
322 ".section .fixup,\"ax\"\n" \
324 " xorl %%eax,%%eax\n" \
325 " xorl %%edx,%%edx\n" \
328 _ASM_EXTABLE(1b, 4b) \
329 _ASM_EXTABLE(2b, 4b) \
330 : "=r" (retval), "=A"(x) \
331 : "m" (__m(__ptr)), "m" __m(((u32 *)(__ptr)) + 1), \
332 "i" (errret), "0" (retval)); \
335 #define __get_user_asm_ex_u64(x, ptr) (x) = __get_user_bad()
337 #define __get_user_asm_u64(x, ptr, retval, errret) \
338 __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
339 #define __get_user_asm_ex_u64(x, ptr) \
340 __get_user_asm_ex(x, ptr, "q", "", "=r")
343 #define __get_user_size(x, ptr, size, retval, errret) \
346 __chk_user_ptr(ptr); \
349 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
352 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
355 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
358 __get_user_asm_u64(x, ptr, retval, errret); \
361 (x) = __get_user_bad(); \
365 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret) \
367 "1: mov"itype" %2,%"rtype"1\n" \
369 ".section .fixup,\"ax\"\n" \
371 " xor"itype" %"rtype"1,%"rtype"1\n" \
374 _ASM_EXTABLE(1b, 3b) \
375 : "=r" (err), ltype(x) \
376 : "m" (__m(addr)), "i" (errret), "0" (err))
379 * This doesn't do __uaccess_begin/end - the exception handling
380 * around it must do that.
382 #define __get_user_size_ex(x, ptr, size) \
384 __chk_user_ptr(ptr); \
387 __get_user_asm_ex(x, ptr, "b", "b", "=q"); \
390 __get_user_asm_ex(x, ptr, "w", "w", "=r"); \
393 __get_user_asm_ex(x, ptr, "l", "k", "=r"); \
396 __get_user_asm_ex_u64(x, ptr); \
399 (x) = __get_user_bad(); \
403 #define __get_user_asm_ex(x, addr, itype, rtype, ltype) \
404 asm volatile("1: mov"itype" %1,%"rtype"0\n" \
406 ".section .fixup,\"ax\"\n" \
407 "3:xor"itype" %"rtype"0,%"rtype"0\n" \
410 _ASM_EXTABLE_EX(1b, 3b) \
411 : ltype(x) : "m" (__m(addr)))
413 #define __put_user_nocheck(x, ptr, size) \
417 __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
419 __builtin_expect(__pu_err, 0); \
422 #define __get_user_nocheck(x, ptr, size) \
425 __inttype(*(ptr)) __gu_val; \
427 __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \
429 (x) = (__force __typeof__(*(ptr)))__gu_val; \
430 __builtin_expect(__gu_err, 0); \
433 /* FIXME: this hack is definitely wrong -AK */
434 struct __large_struct { unsigned long buf[100]; };
435 #define __m(x) (*(struct __large_struct __user *)(x))
438 * Tell gcc we read from memory instead of writing: this is because
439 * we do not write to any memory gcc knows about, so there are no
442 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret) \
444 "1: mov"itype" %"rtype"1,%2\n" \
446 ".section .fixup,\"ax\"\n" \
450 _ASM_EXTABLE(1b, 3b) \
452 : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
454 #define __put_user_asm_ex(x, addr, itype, rtype, ltype) \
455 asm volatile("1: mov"itype" %"rtype"0,%1\n" \
457 _ASM_EXTABLE_EX(1b, 2b) \
458 : : ltype(x), "m" (__m(addr)))
461 * uaccess_try and catch
463 #define uaccess_try do { \
464 current->thread.uaccess_err = 0; \
468 #define uaccess_catch(err) \
470 (err) |= (current->thread.uaccess_err ? -EFAULT : 0); \
474 * __get_user: - Get a simple variable from user space, with less checking.
475 * @x: Variable to store result.
476 * @ptr: Source address, in user space.
478 * Context: User context only. This function may sleep if pagefaults are
481 * This macro copies a single simple variable from user space to kernel
482 * space. It supports simple types like char and int, but not larger
483 * data types like structures or arrays.
485 * @ptr must have pointer-to-simple-variable type, and the result of
486 * dereferencing @ptr must be assignable to @x without a cast.
488 * Caller must check the pointer with access_ok() before calling this
491 * Returns zero on success, or -EFAULT on error.
492 * On error, the variable @x is set to zero.
495 #define __get_user(x, ptr) \
496 __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
499 * __put_user: - Write a simple value into user space, with less checking.
500 * @x: Value to copy to user space.
501 * @ptr: Destination address, in user space.
503 * Context: User context only. This function may sleep if pagefaults are
506 * This macro copies a single simple value from kernel space to user
507 * space. It supports simple types like char and int, but not larger
508 * data types like structures or arrays.
510 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
511 * to the result of dereferencing @ptr.
513 * Caller must check the pointer with access_ok() before calling this
516 * Returns zero on success, or -EFAULT on error.
519 #define __put_user(x, ptr) \
520 __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
522 #define __get_user_unaligned __get_user
523 #define __put_user_unaligned __put_user
526 * {get|put}_user_try and catch
530 * } get_user_catch(err)
532 #define get_user_try uaccess_try
533 #define get_user_catch(err) uaccess_catch(err)
535 #define get_user_ex(x, ptr) do { \
536 unsigned long __gue_val; \
537 __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr)))); \
538 (x) = (__force __typeof__(*(ptr)))__gue_val; \
541 #define put_user_try uaccess_try
542 #define put_user_catch(err) uaccess_catch(err)
544 #define put_user_ex(x, ptr) \
545 __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
548 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
549 extern __must_check long
550 strncpy_from_user(char *dst, const char __user *src, long count);
552 extern __must_check long strlen_user(const char __user *str);
553 extern __must_check long strnlen_user(const char __user *str, long n);
555 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
556 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
558 extern void __cmpxchg_wrong_size(void)
559 __compiletime_error("Bad argument size for cmpxchg");
561 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size) \
564 __typeof__(ptr) __uval = (uval); \
565 __typeof__(*(ptr)) __old = (old); \
566 __typeof__(*(ptr)) __new = (new); \
572 "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n" \
574 "\t.section .fixup, \"ax\"\n" \
578 _ASM_EXTABLE(1b, 3b) \
579 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
580 : "i" (-EFAULT), "q" (__new), "1" (__old) \
588 "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n" \
590 "\t.section .fixup, \"ax\"\n" \
594 _ASM_EXTABLE(1b, 3b) \
595 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
596 : "i" (-EFAULT), "r" (__new), "1" (__old) \
604 "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n" \
606 "\t.section .fixup, \"ax\"\n" \
610 _ASM_EXTABLE(1b, 3b) \
611 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
612 : "i" (-EFAULT), "r" (__new), "1" (__old) \
619 if (!IS_ENABLED(CONFIG_X86_64)) \
620 __cmpxchg_wrong_size(); \
623 "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n" \
625 "\t.section .fixup, \"ax\"\n" \
629 _ASM_EXTABLE(1b, 3b) \
630 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
631 : "i" (-EFAULT), "r" (__new), "1" (__old) \
637 __cmpxchg_wrong_size(); \
644 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new) \
646 access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ? \
647 __user_atomic_cmpxchg_inatomic((uval), (ptr), \
648 (old), (new), sizeof(*(ptr))) : \
653 * movsl can be slow when source and dest are not both 8-byte aligned
655 #ifdef CONFIG_X86_INTEL_USERCOPY
656 extern struct movsl_mask {
658 } ____cacheline_aligned_in_smp movsl_mask;
661 #define ARCH_HAS_NOCACHE_UACCESS 1
664 # include <asm/uaccess_32.h>
666 # include <asm/uaccess_64.h>
669 unsigned long __must_check _copy_from_user(void *to, const void __user *from,
671 unsigned long __must_check _copy_to_user(void __user *to, const void *from,
674 extern void __compiletime_error("usercopy buffer size is too small")
675 __bad_copy_user(void);
677 static inline void copy_user_overflow(int size, unsigned long count)
679 WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
682 static __always_inline unsigned long __must_check
683 copy_from_user(void *to, const void __user *from, unsigned long n)
685 int sz = __compiletime_object_size(to);
689 kasan_check_write(to, n);
691 if (likely(sz < 0 || sz >= n)) {
692 check_object_size(to, n, false);
693 n = _copy_from_user(to, from, n);
694 } else if (!__builtin_constant_p(n))
695 copy_user_overflow(sz, n);
702 static __always_inline unsigned long __must_check
703 copy_to_user(void __user *to, const void *from, unsigned long n)
705 int sz = __compiletime_object_size(from);
707 kasan_check_read(from, n);
711 if (likely(sz < 0 || sz >= n)) {
712 check_object_size(from, n, true);
713 n = _copy_to_user(to, from, n);
714 } else if (!__builtin_constant_p(n))
715 copy_user_overflow(sz, n);
723 * We rely on the nested NMI work to allow atomic faults from the NMI path; the
724 * nested NMI paths are careful to preserve CR2.
726 * Caller must use pagefault_enable/disable, or run in interrupt context,
727 * and also do a uaccess_ok() check
729 #define __copy_from_user_nmi __copy_from_user_inatomic
732 * The "unsafe" user accesses aren't really "unsafe", but the naming
733 * is a big fat warning: you have to not only do the access_ok()
734 * checking before using them, but you have to surround them with the
735 * user_access_begin/end() pair.
737 #define user_access_begin() __uaccess_begin()
738 #define user_access_end() __uaccess_end()
740 #define unsafe_put_user(x, ptr, err_label) \
743 __put_user_size((x), (ptr), sizeof(*(ptr)), __pu_err, -EFAULT); \
744 if (unlikely(__pu_err)) goto err_label; \
747 #define unsafe_get_user(x, ptr, err_label) \
750 unsigned long __gu_val; \
751 __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT); \
752 (x) = (__force __typeof__(*(ptr)))__gu_val; \
753 if (unlikely(__gu_err)) goto err_label; \
756 #endif /* _ASM_X86_UACCESS_H */