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#ifdef CONFIG_UACCESS_MEMCPY
13#include <asm/unaligned.h>
14
15static __always_inline int
16__get_user_fn(size_t size, const void __user *from, void *to)
17{
18	BUILD_BUG_ON(!__builtin_constant_p(size));
19
20	switch (size) {
21	case 1:
22		*(u8 *)to = get_unaligned((u8 __force *)from);
23		return 0;
24	case 2:
25		*(u16 *)to = get_unaligned((u16 __force *)from);
26		return 0;
27	case 4:
28		*(u32 *)to = get_unaligned((u32 __force *)from);
29		return 0;
30	case 8:
31		*(u64 *)to = get_unaligned((u64 __force *)from);
32		return 0;
33	default:
34		BUILD_BUG();
35		return 0;
36	}
37
38}
39#define __get_user_fn(sz, u, k)	__get_user_fn(sz, u, k)
40
41static __always_inline int
42__put_user_fn(size_t size, void __user *to, void *from)
43{
44	BUILD_BUG_ON(!__builtin_constant_p(size));
45
46	switch (size) {
47	case 1:
48		put_unaligned(*(u8 *)from, (u8 __force *)to);
49		return 0;
50	case 2:
51		put_unaligned(*(u16 *)from, (u16 __force *)to);
52		return 0;
53	case 4:
54		put_unaligned(*(u32 *)from, (u32 __force *)to);
55		return 0;
56	case 8:
57		put_unaligned(*(u64 *)from, (u64 __force *)to);
58		return 0;
59	default:
60		BUILD_BUG();
61		return 0;
62	}
63}
64#define __put_user_fn(sz, u, k)	__put_user_fn(sz, u, k)
65
66#define __get_kernel_nofault(dst, src, type, err_label)			\
67do {									\
68	*((type *)dst) = get_unaligned((type *)(src));			\
69	if (0) /* make sure the label looks used to the compiler */	\
70		goto err_label;						\
71} while (0)
72
73#define __put_kernel_nofault(dst, src, type, err_label)			\
74do {									\
75	put_unaligned(*((type *)src), (type *)(dst));			\
76	if (0) /* make sure the label looks used to the compiler */	\
77		goto err_label;						\
78} while (0)
79
80#define HAVE_GET_KERNEL_NOFAULT 1
81
82static inline __must_check unsigned long
83raw_copy_from_user(void *to, const void __user * from, unsigned long n)
84{
85	memcpy(to, (const void __force *)from, n);
86	return 0;
87}
88
89static inline __must_check unsigned long
90raw_copy_to_user(void __user *to, const void *from, unsigned long n)
91{
92	memcpy((void __force *)to, from, n);
93	return 0;
94}
95#define INLINE_COPY_FROM_USER
96#define INLINE_COPY_TO_USER
97#endif /* CONFIG_UACCESS_MEMCPY */
98
99#ifdef CONFIG_SET_FS
100#define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })
101
102#ifndef KERNEL_DS
103#define KERNEL_DS	MAKE_MM_SEG(~0UL)
104#endif
105
106#ifndef USER_DS
107#define USER_DS		MAKE_MM_SEG(TASK_SIZE - 1)
108#endif
109
110#ifndef get_fs
111#define get_fs()	(current_thread_info()->addr_limit)
112
113static inline void set_fs(mm_segment_t fs)
114{
115	current_thread_info()->addr_limit = fs;
116}
117#endif
118
119#ifndef uaccess_kernel
120#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
121#endif
122#endif /* CONFIG_SET_FS */
123
124#define access_ok(addr, size) __access_ok((unsigned long)(addr),(size))
125
126/*
127 * The architecture should really override this if possible, at least
128 * doing a check on the get_fs()
129 */
130#ifndef __access_ok
131static inline int __access_ok(unsigned long addr, unsigned long size)
132{
133	return 1;
134}
135#endif
136
137/*
138 * These are the main single-value transfer routines.  They automatically
139 * use the right size if we just have the right pointer type.
140 * This version just falls back to copy_{from,to}_user, which should
141 * provide a fast-path for small values.
142 */
143#define __put_user(x, ptr) \
144({								\
145	__typeof__(*(ptr)) __x = (x);				\
146	int __pu_err = -EFAULT;					\
147        __chk_user_ptr(ptr);                                    \
148	switch (sizeof (*(ptr))) {				\
149	case 1:							\
150	case 2:							\
151	case 4:							\
152	case 8:							\
153		__pu_err = __put_user_fn(sizeof (*(ptr)),	\
154					 ptr, &__x);		\
155		break;						\
156	default:						\
157		__put_user_bad();				\
158		break;						\
159	 }							\
160	__pu_err;						\
161})
162
163#define put_user(x, ptr)					\
164({								\
165	void __user *__p = (ptr);				\
166	might_fault();						\
167	access_ok(__p, sizeof(*ptr)) ?		\
168		__put_user((x), ((__typeof__(*(ptr)) __user *)__p)) :	\
169		-EFAULT;					\
170})
171
172#ifndef __put_user_fn
173
174static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
175{
176	return unlikely(raw_copy_to_user(ptr, x, size)) ? -EFAULT : 0;
177}
178
179#define __put_user_fn(sz, u, k)	__put_user_fn(sz, u, k)
180
181#endif
182
183extern int __put_user_bad(void) __attribute__((noreturn));
184
185#define __get_user(x, ptr)					\
186({								\
187	int __gu_err = -EFAULT;					\
188	__chk_user_ptr(ptr);					\
189	switch (sizeof(*(ptr))) {				\
190	case 1: {						\
191		unsigned char __x = 0;				\
192		__gu_err = __get_user_fn(sizeof (*(ptr)),	\
193					 ptr, &__x);		\
194		(x) = *(__force __typeof__(*(ptr)) *) &__x;	\
195		break;						\
196	};							\
197	case 2: {						\
198		unsigned short __x = 0;				\
199		__gu_err = __get_user_fn(sizeof (*(ptr)),	\
200					 ptr, &__x);		\
201		(x) = *(__force __typeof__(*(ptr)) *) &__x;	\
202		break;						\
203	};							\
204	case 4: {						\
205		unsigned int __x = 0;				\
206		__gu_err = __get_user_fn(sizeof (*(ptr)),	\
207					 ptr, &__x);		\
208		(x) = *(__force __typeof__(*(ptr)) *) &__x;	\
209		break;						\
210	};							\
211	case 8: {						\
212		unsigned long long __x = 0;			\
213		__gu_err = __get_user_fn(sizeof (*(ptr)),	\
214					 ptr, &__x);		\
215		(x) = *(__force __typeof__(*(ptr)) *) &__x;	\
216		break;						\
217	};							\
218	default:						\
219		__get_user_bad();				\
220		break;						\
221	}							\
222	__gu_err;						\
223})
224
225#define get_user(x, ptr)					\
226({								\
227	const void __user *__p = (ptr);				\
228	might_fault();						\
229	access_ok(__p, sizeof(*ptr)) ?		\
230		__get_user((x), (__typeof__(*(ptr)) __user *)__p) :\
231		((x) = (__typeof__(*(ptr)))0,-EFAULT);		\
232})
233
234#ifndef __get_user_fn
235static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
236{
237	return unlikely(raw_copy_from_user(x, ptr, size)) ? -EFAULT : 0;
238}
239
240#define __get_user_fn(sz, u, k)	__get_user_fn(sz, u, k)
241
242#endif
243
244extern int __get_user_bad(void) __attribute__((noreturn));
245
246/*
247 * Copy a null terminated string from userspace.
248 */
249#ifndef __strncpy_from_user
250static inline long
251__strncpy_from_user(char *dst, const char __user *src, long count)
252{
253	char *tmp;
254	strncpy(dst, (const char __force *)src, count);
255	for (tmp = dst; *tmp && count > 0; tmp++, count--)
256		;
257	return (tmp - dst);
258}
259#endif
260
261static inline long
262strncpy_from_user(char *dst, const char __user *src, long count)
263{
264	if (!access_ok(src, 1))
265		return -EFAULT;
266	return __strncpy_from_user(dst, src, count);
267}
268
269/*
270 * Return the size of a string (including the ending 0)
271 *
272 * Return 0 on exception, a value greater than N if too long
273 */
274#ifndef __strnlen_user
275#define __strnlen_user(s, n) (strnlen((s), (n)) + 1)
276#endif
277
278/*
279 * Unlike strnlen, strnlen_user includes the nul terminator in
280 * its returned count. Callers should check for a returned value
281 * greater than N as an indication the string is too long.
282 */
283static inline long strnlen_user(const char __user *src, long n)
284{
285	if (!access_ok(src, 1))
286		return 0;
287	return __strnlen_user(src, n);
288}
289
290/*
291 * Zero Userspace
292 */
293#ifndef __clear_user
294static inline __must_check unsigned long
295__clear_user(void __user *to, unsigned long n)
296{
297	memset((void __force *)to, 0, n);
298	return 0;
299}
300#endif
301
302static inline __must_check unsigned long
303clear_user(void __user *to, unsigned long n)
304{
305	might_fault();
306	if (!access_ok(to, n))
307		return n;
308
309	return __clear_user(to, n);
310}
311
312#include <asm/extable.h>
313
314#endif /* __ASM_GENERIC_UACCESS_H */
315