Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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
28static 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
45static 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
88static 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
97extern 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
149static 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
158extern int __get_user_bad(void) __attribute__((noreturn));
159
160/*
161 * Copy a null terminated string from userspace.
162 */
163#ifndef __strncpy_from_user
164static 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
175static inline long
176strncpy_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 */
197static 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
208static 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
216static inline __must_check unsigned long
217clear_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 */