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