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
set_fs(mm_segment_t fs)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
__access_ok(unsigned long addr,unsigned long size)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
__put_user_fn(size_t size,void __user * ptr,void * x)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
__get_user_fn(size_t size,const void __user * ptr,void * x)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
__strncpy_from_user(char * dst,const char __user * src,long count)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
strncpy_from_user(char * dst,const char __user * src,long count)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 */
strnlen_user(const char __user * src,long n)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
__clear_user(void __user * to,unsigned long n)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
clear_user(void __user * to,unsigned long n)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 */
229