GNU Linux-libre 4.19.211-gnu1
[releases.git] / include / asm-generic / uaccess.h
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __ASM_GENERIC_UACCESS_H
3 #define __ASM_GENERIC_UACCESS_H
4
5 /*
6  * User space memory access functions, these should work
7  * on any machine that has kernel and user data in the same
8  * address space, e.g. all NOMMU machines.
9  */
10 #include <linux/string.h>
11
12 #include <asm/segment.h>
13
14 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
15
16 #ifndef KERNEL_DS
17 #define KERNEL_DS       MAKE_MM_SEG(~0UL)
18 #endif
19
20 #ifndef USER_DS
21 #define USER_DS         MAKE_MM_SEG(TASK_SIZE - 1)
22 #endif
23
24 #ifndef get_fs
25 #define get_ds()        (KERNEL_DS)
26 #define get_fs()        (current_thread_info()->addr_limit)
27
28 static inline void set_fs(mm_segment_t fs)
29 {
30         current_thread_info()->addr_limit = fs;
31 }
32 #endif
33
34 #ifndef segment_eq
35 #define segment_eq(a, b) ((a).seg == (b).seg)
36 #endif
37
38 #define access_ok(type, addr, size) __access_ok((unsigned long)(addr),(size))
39
40 /*
41  * The architecture should really override this if possible, at least
42  * doing a check on the get_fs()
43  */
44 #ifndef __access_ok
45 static inline int __access_ok(unsigned long addr, unsigned long size)
46 {
47         return 1;
48 }
49 #endif
50
51 /*
52  * These are the main single-value transfer routines.  They automatically
53  * use the right size if we just have the right pointer type.
54  * This version just falls back to copy_{from,to}_user, which should
55  * provide a fast-path for small values.
56  */
57 #define __put_user(x, ptr) \
58 ({                                                              \
59         __typeof__(*(ptr)) __x = (x);                           \
60         int __pu_err = -EFAULT;                                 \
61         __chk_user_ptr(ptr);                                    \
62         switch (sizeof (*(ptr))) {                              \
63         case 1:                                                 \
64         case 2:                                                 \
65         case 4:                                                 \
66         case 8:                                                 \
67                 __pu_err = __put_user_fn(sizeof (*(ptr)),       \
68                                          ptr, &__x);            \
69                 break;                                          \
70         default:                                                \
71                 __put_user_bad();                               \
72                 break;                                          \
73          }                                                      \
74         __pu_err;                                               \
75 })
76
77 #define put_user(x, ptr)                                        \
78 ({                                                              \
79         void __user *__p = (ptr);                               \
80         might_fault();                                          \
81         access_ok(VERIFY_WRITE, __p, sizeof(*ptr)) ?            \
82                 __put_user((x), ((__typeof__(*(ptr)) __user *)__p)) :   \
83                 -EFAULT;                                        \
84 })
85
86 #ifndef __put_user_fn
87
88 static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
89 {
90         return unlikely(raw_copy_to_user(ptr, x, size)) ? -EFAULT : 0;
91 }
92
93 #define __put_user_fn(sz, u, k) __put_user_fn(sz, u, k)
94
95 #endif
96
97 extern int __put_user_bad(void) __attribute__((noreturn));
98
99 #define __get_user(x, ptr)                                      \
100 ({                                                              \
101         int __gu_err = -EFAULT;                                 \
102         __chk_user_ptr(ptr);                                    \
103         switch (sizeof(*(ptr))) {                               \
104         case 1: {                                               \
105                 unsigned char __x = 0;                          \
106                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
107                                          ptr, &__x);            \
108                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
109                 break;                                          \
110         };                                                      \
111         case 2: {                                               \
112                 unsigned short __x = 0;                         \
113                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
114                                          ptr, &__x);            \
115                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
116                 break;                                          \
117         };                                                      \
118         case 4: {                                               \
119                 unsigned int __x = 0;                           \
120                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
121                                          ptr, &__x);            \
122                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
123                 break;                                          \
124         };                                                      \
125         case 8: {                                               \
126                 unsigned long long __x = 0;                     \
127                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
128                                          ptr, &__x);            \
129                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
130                 break;                                          \
131         };                                                      \
132         default:                                                \
133                 __get_user_bad();                               \
134                 break;                                          \
135         }                                                       \
136         __gu_err;                                               \
137 })
138
139 #define get_user(x, ptr)                                        \
140 ({                                                              \
141         const void __user *__p = (ptr);                         \
142         might_fault();                                          \
143         access_ok(VERIFY_READ, __p, sizeof(*ptr)) ?             \
144                 __get_user((x), (__typeof__(*(ptr)) __user *)__p) :\
145                 ((x) = (__typeof__(*(ptr)))0,-EFAULT);          \
146 })
147
148 #ifndef __get_user_fn
149 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
150 {
151         return unlikely(raw_copy_from_user(x, ptr, size)) ? -EFAULT : 0;
152 }
153
154 #define __get_user_fn(sz, u, k) __get_user_fn(sz, u, k)
155
156 #endif
157
158 extern int __get_user_bad(void) __attribute__((noreturn));
159
160 /*
161  * Copy a null terminated string from userspace.
162  */
163 #ifndef __strncpy_from_user
164 static inline long
165 __strncpy_from_user(char *dst, const char __user *src, long count)
166 {
167         char *tmp;
168         strncpy(dst, (const char __force *)src, count);
169         for (tmp = dst; *tmp && count > 0; tmp++, count--)
170                 ;
171         return (tmp - dst);
172 }
173 #endif
174
175 static inline long
176 strncpy_from_user(char *dst, const char __user *src, long count)
177 {
178         if (!access_ok(VERIFY_READ, src, 1))
179                 return -EFAULT;
180         return __strncpy_from_user(dst, src, count);
181 }
182
183 /*
184  * Return the size of a string (including the ending 0)
185  *
186  * Return 0 on exception, a value greater than N if too long
187  */
188 #ifndef __strnlen_user
189 #define __strnlen_user(s, n) (strnlen((s), (n)) + 1)
190 #endif
191
192 /*
193  * Unlike strnlen, strnlen_user includes the nul terminator in
194  * its returned count. Callers should check for a returned value
195  * greater than N as an indication the string is too long.
196  */
197 static inline long strnlen_user(const char __user *src, long n)
198 {
199         if (!access_ok(VERIFY_READ, src, 1))
200                 return 0;
201         return __strnlen_user(src, n);
202 }
203
204 /*
205  * Zero Userspace
206  */
207 #ifndef __clear_user
208 static inline __must_check unsigned long
209 __clear_user(void __user *to, unsigned long n)
210 {
211         memset((void __force *)to, 0, n);
212         return 0;
213 }
214 #endif
215
216 static inline __must_check unsigned long
217 clear_user(void __user *to, unsigned long n)
218 {
219         might_fault();
220         if (!access_ok(VERIFY_WRITE, to, n))
221                 return n;
222
223         return __clear_user(to, n);
224 }
225
226 #include <asm/extable.h>
227
228 #endif /* __ASM_GENERIC_UACCESS_H */