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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
c22ce143 HY |
2 | #ifndef __LINUX_UACCESS_H__ |
3 | #define __LINUX_UACCESS_H__ | |
4 | ||
8bcbde54 | 5 | #include <linux/sched.h> |
af1d5b37 | 6 | #include <linux/thread_info.h> |
d597580d | 7 | #include <linux/kasan-checks.h> |
5e6039d8 | 8 | |
db68ce10 AV |
9 | #define uaccess_kernel() segment_eq(get_fs(), KERNEL_DS) |
10 | ||
c22ce143 HY |
11 | #include <asm/uaccess.h> |
12 | ||
d597580d AV |
13 | /* |
14 | * Architectures should provide two primitives (raw_copy_{to,from}_user()) | |
701cac61 AV |
15 | * and get rid of their private instances of copy_{to,from}_user() and |
16 | * __copy_{to,from}_user{,_inatomic}(). | |
d597580d AV |
17 | * |
18 | * raw_copy_{to,from}_user(to, from, size) should copy up to size bytes and | |
19 | * return the amount left to copy. They should assume that access_ok() has | |
20 | * already been checked (and succeeded); they should *not* zero-pad anything. | |
21 | * No KASAN or object size checks either - those belong here. | |
22 | * | |
23 | * Both of these functions should attempt to copy size bytes starting at from | |
24 | * into the area starting at to. They must not fetch or store anything | |
25 | * outside of those areas. Return value must be between 0 (everything | |
26 | * copied successfully) and size (nothing copied). | |
27 | * | |
28 | * If raw_copy_{to,from}_user(to, from, size) returns N, size - N bytes starting | |
29 | * at to must become equal to the bytes fetched from the corresponding area | |
30 | * starting at from. All data past to + size - N must be left unmodified. | |
31 | * | |
32 | * If copying succeeds, the return value must be 0. If some data cannot be | |
33 | * fetched, it is permitted to copy less than had been fetched; the only | |
34 | * hard requirement is that not storing anything at all (i.e. returning size) | |
35 | * should happen only when nothing could be copied. In other words, you don't | |
36 | * have to squeeze as much as possible - it is allowed, but not necessary. | |
37 | * | |
38 | * For raw_copy_from_user() to always points to kernel memory and no faults | |
39 | * on store should happen. Interpretation of from is affected by set_fs(). | |
40 | * For raw_copy_to_user() it's the other way round. | |
41 | * | |
42 | * Both can be inlined - it's up to architectures whether it wants to bother | |
43 | * with that. They should not be used directly; they are used to implement | |
44 | * the 6 functions (copy_{to,from}_user(), __copy_{to,from}_user_inatomic()) | |
45 | * that are used instead. Out of those, __... ones are inlined. Plain | |
46 | * copy_{to,from}_user() might or might not be inlined. If you want them | |
47 | * inlined, have asm/uaccess.h define INLINE_COPY_{TO,FROM}_USER. | |
48 | * | |
49 | * NOTE: only copy_from_user() zero-pads the destination in case of short copy. | |
50 | * Neither __copy_from_user() nor __copy_from_user_inatomic() zero anything | |
51 | * at all; their callers absolutely must check the return value. | |
52 | * | |
53 | * Biarch ones should also provide raw_copy_in_user() - similar to the above, | |
54 | * but both source and destination are __user pointers (affected by set_fs() | |
55 | * as usual) and both source and destination can trigger faults. | |
56 | */ | |
57 | ||
58 | static __always_inline unsigned long | |
59 | __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n) | |
60 | { | |
61 | kasan_check_write(to, n); | |
62 | check_object_size(to, n, false); | |
63 | return raw_copy_from_user(to, from, n); | |
64 | } | |
65 | ||
66 | static __always_inline unsigned long | |
67 | __copy_from_user(void *to, const void __user *from, unsigned long n) | |
68 | { | |
69 | might_fault(); | |
70 | kasan_check_write(to, n); | |
71 | check_object_size(to, n, false); | |
72 | return raw_copy_from_user(to, from, n); | |
73 | } | |
74 | ||
75 | /** | |
76 | * __copy_to_user_inatomic: - Copy a block of data into user space, with less checking. | |
77 | * @to: Destination address, in user space. | |
78 | * @from: Source address, in kernel space. | |
79 | * @n: Number of bytes to copy. | |
80 | * | |
81 | * Context: User context only. | |
82 | * | |
83 | * Copy data from kernel space to user space. Caller must check | |
84 | * the specified block with access_ok() before calling this function. | |
85 | * The caller should also make sure he pins the user space address | |
86 | * so that we don't result in page fault and sleep. | |
87 | */ | |
88 | static __always_inline unsigned long | |
89 | __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n) | |
90 | { | |
91 | kasan_check_read(from, n); | |
92 | check_object_size(from, n, true); | |
93 | return raw_copy_to_user(to, from, n); | |
94 | } | |
95 | ||
96 | static __always_inline unsigned long | |
97 | __copy_to_user(void __user *to, const void *from, unsigned long n) | |
98 | { | |
99 | might_fault(); | |
100 | kasan_check_read(from, n); | |
101 | check_object_size(from, n, true); | |
102 | return raw_copy_to_user(to, from, n); | |
103 | } | |
104 | ||
105 | #ifdef INLINE_COPY_FROM_USER | |
106 | static inline unsigned long | |
107 | _copy_from_user(void *to, const void __user *from, unsigned long n) | |
108 | { | |
109 | unsigned long res = n; | |
9c5f6908 | 110 | might_fault(); |
96d4f267 | 111 | if (likely(access_ok(from, n))) { |
9c5f6908 | 112 | kasan_check_write(to, n); |
d597580d | 113 | res = raw_copy_from_user(to, from, n); |
9c5f6908 | 114 | } |
d597580d AV |
115 | if (unlikely(res)) |
116 | memset(to + (n - res), 0, res); | |
117 | return res; | |
118 | } | |
119 | #else | |
120 | extern unsigned long | |
121 | _copy_from_user(void *, const void __user *, unsigned long); | |
122 | #endif | |
123 | ||
124 | #ifdef INLINE_COPY_TO_USER | |
125 | static inline unsigned long | |
126 | _copy_to_user(void __user *to, const void *from, unsigned long n) | |
127 | { | |
9c5f6908 | 128 | might_fault(); |
96d4f267 | 129 | if (access_ok(to, n)) { |
9c5f6908 | 130 | kasan_check_read(from, n); |
d597580d | 131 | n = raw_copy_to_user(to, from, n); |
9c5f6908 | 132 | } |
d597580d AV |
133 | return n; |
134 | } | |
135 | #else | |
136 | extern unsigned long | |
137 | _copy_to_user(void __user *, const void *, unsigned long); | |
138 | #endif | |
139 | ||
d597580d AV |
140 | static __always_inline unsigned long __must_check |
141 | copy_from_user(void *to, const void __user *from, unsigned long n) | |
142 | { | |
b0377fed | 143 | if (likely(check_copy_size(to, n, false))) |
d597580d | 144 | n = _copy_from_user(to, from, n); |
d597580d AV |
145 | return n; |
146 | } | |
147 | ||
148 | static __always_inline unsigned long __must_check | |
149 | copy_to_user(void __user *to, const void *from, unsigned long n) | |
150 | { | |
b0377fed | 151 | if (likely(check_copy_size(from, n, true))) |
d597580d | 152 | n = _copy_to_user(to, from, n); |
d597580d AV |
153 | return n; |
154 | } | |
155 | #ifdef CONFIG_COMPAT | |
156 | static __always_inline unsigned long __must_check | |
f58e76c1 | 157 | copy_in_user(void __user *to, const void __user *from, unsigned long n) |
d597580d AV |
158 | { |
159 | might_fault(); | |
96d4f267 | 160 | if (access_ok(to, n) && access_ok(from, n)) |
d597580d AV |
161 | n = raw_copy_in_user(to, from, n); |
162 | return n; | |
163 | } | |
164 | #endif | |
d597580d | 165 | |
8bcbde54 DH |
166 | static __always_inline void pagefault_disabled_inc(void) |
167 | { | |
168 | current->pagefault_disabled++; | |
169 | } | |
170 | ||
171 | static __always_inline void pagefault_disabled_dec(void) | |
172 | { | |
173 | current->pagefault_disabled--; | |
8bcbde54 DH |
174 | } |
175 | ||
a866374a | 176 | /* |
8bcbde54 DH |
177 | * These routines enable/disable the pagefault handler. If disabled, it will |
178 | * not take any locks and go straight to the fixup table. | |
179 | * | |
8222dbe2 DH |
180 | * User access methods will not sleep when called from a pagefault_disabled() |
181 | * environment. | |
a866374a PZ |
182 | */ |
183 | static inline void pagefault_disable(void) | |
184 | { | |
8bcbde54 | 185 | pagefault_disabled_inc(); |
a866374a PZ |
186 | /* |
187 | * make sure to have issued the store before a pagefault | |
188 | * can hit. | |
189 | */ | |
190 | barrier(); | |
191 | } | |
192 | ||
193 | static inline void pagefault_enable(void) | |
194 | { | |
195 | /* | |
196 | * make sure to issue those last loads/stores before enabling | |
197 | * the pagefault handler again. | |
198 | */ | |
199 | barrier(); | |
8bcbde54 | 200 | pagefault_disabled_dec(); |
a866374a PZ |
201 | } |
202 | ||
8bcbde54 DH |
203 | /* |
204 | * Is the pagefault handler disabled? If so, user access methods will not sleep. | |
205 | */ | |
2d8d8fac MH |
206 | static inline bool pagefault_disabled(void) |
207 | { | |
208 | return current->pagefault_disabled != 0; | |
209 | } | |
8bcbde54 | 210 | |
70ffdb93 DH |
211 | /* |
212 | * The pagefault handler is in general disabled by pagefault_disable() or | |
213 | * when in irq context (via in_atomic()). | |
214 | * | |
215 | * This function should only be used by the fault handlers. Other users should | |
216 | * stick to pagefault_disabled(). | |
217 | * Please NEVER use preempt_disable() to disable the fault handler. With | |
218 | * !CONFIG_PREEMPT_COUNT, this is like a NOP. So the handler won't be disabled. | |
219 | * in_atomic() will report different values based on !CONFIG_PREEMPT_COUNT. | |
220 | */ | |
221 | #define faulthandler_disabled() (pagefault_disabled() || in_atomic()) | |
222 | ||
c22ce143 HY |
223 | #ifndef ARCH_HAS_NOCACHE_UACCESS |
224 | ||
225 | static inline unsigned long __copy_from_user_inatomic_nocache(void *to, | |
226 | const void __user *from, unsigned long n) | |
227 | { | |
228 | return __copy_from_user_inatomic(to, from, n); | |
229 | } | |
230 | ||
c22ce143 HY |
231 | #endif /* ARCH_HAS_NOCACHE_UACCESS */ |
232 | ||
c33fa9f5 IM |
233 | /* |
234 | * probe_kernel_read(): safely attempt to read from a location | |
235 | * @dst: pointer to the buffer that shall take the data | |
236 | * @src: address to read from | |
237 | * @size: size of the data chunk | |
238 | * | |
239 | * Safely read from address @src to the buffer at @dst. If a kernel fault | |
240 | * happens, handle that and return -EFAULT. | |
241 | */ | |
f29c5041 SR |
242 | extern long probe_kernel_read(void *dst, const void *src, size_t size); |
243 | extern long __probe_kernel_read(void *dst, const void *src, size_t size); | |
c33fa9f5 IM |
244 | |
245 | /* | |
246 | * probe_kernel_write(): safely attempt to write to a location | |
247 | * @dst: address to write to | |
248 | * @src: pointer to the data that shall be written | |
249 | * @size: size of the data chunk | |
250 | * | |
251 | * Safely write to address @dst from the buffer at @src. If a kernel fault | |
252 | * happens, handle that and return -EFAULT. | |
253 | */ | |
f29c5041 SR |
254 | extern long notrace probe_kernel_write(void *dst, const void *src, size_t size); |
255 | extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size); | |
c33fa9f5 | 256 | |
1a6877b9 AS |
257 | extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count); |
258 | ||
0ab32b6f AM |
259 | /** |
260 | * probe_kernel_address(): safely attempt to read from a location | |
261 | * @addr: address to read from | |
262 | * @retval: read into this variable | |
263 | * | |
264 | * Returns 0 on success, or -EFAULT. | |
265 | */ | |
266 | #define probe_kernel_address(addr, retval) \ | |
267 | probe_kernel_read(&retval, addr, sizeof(retval)) | |
268 | ||
5b24a7a2 | 269 | #ifndef user_access_begin |
594cc251 | 270 | #define user_access_begin(ptr,len) access_ok(ptr, len) |
5b24a7a2 | 271 | #define user_access_end() do { } while (0) |
1bd4403d LT |
272 | #define unsafe_get_user(x, ptr, err) do { if (unlikely(__get_user(x, ptr))) goto err; } while (0) |
273 | #define unsafe_put_user(x, ptr, err) do { if (unlikely(__put_user(x, ptr))) goto err; } while (0) | |
e74deb11 PZ |
274 | static inline unsigned long user_access_save(void) { return 0UL; } |
275 | static inline void user_access_restore(unsigned long flags) { } | |
5b24a7a2 LT |
276 | #endif |
277 | ||
b394d468 | 278 | #ifdef CONFIG_HARDENED_USERCOPY |
afcc90f8 KC |
279 | void usercopy_warn(const char *name, const char *detail, bool to_user, |
280 | unsigned long offset, unsigned long len); | |
b394d468 KC |
281 | void __noreturn usercopy_abort(const char *name, const char *detail, |
282 | bool to_user, unsigned long offset, | |
283 | unsigned long len); | |
284 | #endif | |
285 | ||
c22ce143 | 286 | #endif /* __LINUX_UACCESS_H__ */ |