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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 | ||
76d6f06c | 5 | #include <linux/instrumented.h> |
8bcbde54 | 6 | #include <linux/sched.h> |
af1d5b37 | 7 | #include <linux/thread_info.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 | ||
9dd819a1 | 58 | static __always_inline __must_check unsigned long |
d597580d AV |
59 | __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n) |
60 | { | |
76d6f06c | 61 | instrument_copy_from_user(to, from, n); |
d597580d AV |
62 | check_object_size(to, n, false); |
63 | return raw_copy_from_user(to, from, n); | |
64 | } | |
65 | ||
9dd819a1 | 66 | static __always_inline __must_check unsigned long |
d597580d AV |
67 | __copy_from_user(void *to, const void __user *from, unsigned long n) |
68 | { | |
69 | might_fault(); | |
76d6f06c | 70 | instrument_copy_from_user(to, from, n); |
d597580d AV |
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 | */ | |
9dd819a1 | 88 | static __always_inline __must_check unsigned long |
d597580d AV |
89 | __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n) |
90 | { | |
76d6f06c | 91 | instrument_copy_to_user(to, from, n); |
d597580d AV |
92 | check_object_size(from, n, true); |
93 | return raw_copy_to_user(to, from, n); | |
94 | } | |
95 | ||
9dd819a1 | 96 | static __always_inline __must_check unsigned long |
d597580d AV |
97 | __copy_to_user(void __user *to, const void *from, unsigned long n) |
98 | { | |
99 | might_fault(); | |
76d6f06c | 100 | instrument_copy_to_user(to, from, n); |
d597580d AV |
101 | check_object_size(from, n, true); |
102 | return raw_copy_to_user(to, from, n); | |
103 | } | |
104 | ||
105 | #ifdef INLINE_COPY_FROM_USER | |
9dd819a1 | 106 | static inline __must_check unsigned long |
d597580d AV |
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))) { |
76d6f06c | 112 | instrument_copy_from_user(to, from, 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 | |
9dd819a1 | 120 | extern __must_check unsigned long |
d597580d AV |
121 | _copy_from_user(void *, const void __user *, unsigned long); |
122 | #endif | |
123 | ||
124 | #ifdef INLINE_COPY_TO_USER | |
9dd819a1 | 125 | static inline __must_check unsigned long |
d597580d AV |
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)) { |
76d6f06c | 130 | instrument_copy_to_user(to, from, n); |
d597580d | 131 | n = raw_copy_to_user(to, from, n); |
9c5f6908 | 132 | } |
d597580d AV |
133 | return n; |
134 | } | |
135 | #else | |
9dd819a1 | 136 | extern __must_check unsigned long |
d597580d AV |
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 | ||
9dd819a1 KC |
225 | static inline __must_check unsigned long |
226 | __copy_from_user_inatomic_nocache(void *to, const void __user *from, | |
227 | unsigned long n) | |
c22ce143 HY |
228 | { |
229 | return __copy_from_user_inatomic(to, from, n); | |
230 | } | |
231 | ||
c22ce143 HY |
232 | #endif /* ARCH_HAS_NOCACHE_UACCESS */ |
233 | ||
f5a1a536 AS |
234 | extern __must_check int check_zeroed_user(const void __user *from, size_t size); |
235 | ||
236 | /** | |
237 | * copy_struct_from_user: copy a struct from userspace | |
238 | * @dst: Destination address, in kernel space. This buffer must be @ksize | |
239 | * bytes long. | |
240 | * @ksize: Size of @dst struct. | |
241 | * @src: Source address, in userspace. | |
242 | * @usize: (Alleged) size of @src struct. | |
243 | * | |
244 | * Copies a struct from userspace to kernel space, in a way that guarantees | |
245 | * backwards-compatibility for struct syscall arguments (as long as future | |
246 | * struct extensions are made such that all new fields are *appended* to the | |
247 | * old struct, and zeroed-out new fields have the same meaning as the old | |
248 | * struct). | |
249 | * | |
250 | * @ksize is just sizeof(*dst), and @usize should've been passed by userspace. | |
251 | * The recommended usage is something like the following: | |
252 | * | |
253 | * SYSCALL_DEFINE2(foobar, const struct foo __user *, uarg, size_t, usize) | |
254 | * { | |
255 | * int err; | |
256 | * struct foo karg = {}; | |
257 | * | |
258 | * if (usize > PAGE_SIZE) | |
259 | * return -E2BIG; | |
260 | * if (usize < FOO_SIZE_VER0) | |
261 | * return -EINVAL; | |
262 | * | |
263 | * err = copy_struct_from_user(&karg, sizeof(karg), uarg, usize); | |
264 | * if (err) | |
265 | * return err; | |
266 | * | |
267 | * // ... | |
268 | * } | |
269 | * | |
270 | * There are three cases to consider: | |
271 | * * If @usize == @ksize, then it's copied verbatim. | |
272 | * * If @usize < @ksize, then the userspace has passed an old struct to a | |
273 | * newer kernel. The rest of the trailing bytes in @dst (@ksize - @usize) | |
274 | * are to be zero-filled. | |
275 | * * If @usize > @ksize, then the userspace has passed a new struct to an | |
276 | * older kernel. The trailing bytes unknown to the kernel (@usize - @ksize) | |
277 | * are checked to ensure they are zeroed, otherwise -E2BIG is returned. | |
278 | * | |
279 | * Returns (in all cases, some data may have been copied): | |
280 | * * -E2BIG: (@usize > @ksize) and there are non-zero trailing bytes in @src. | |
281 | * * -EFAULT: access to userspace failed. | |
282 | */ | |
283 | static __always_inline __must_check int | |
284 | copy_struct_from_user(void *dst, size_t ksize, const void __user *src, | |
285 | size_t usize) | |
286 | { | |
287 | size_t size = min(ksize, usize); | |
288 | size_t rest = max(ksize, usize) - size; | |
289 | ||
290 | /* Deal with trailing bytes. */ | |
291 | if (usize < ksize) { | |
292 | memset(dst + size, 0, rest); | |
293 | } else if (usize > ksize) { | |
294 | int ret = check_zeroed_user(src + size, rest); | |
295 | if (ret <= 0) | |
296 | return ret ?: -E2BIG; | |
297 | } | |
298 | /* Copy the interoperable parts of the struct. */ | |
299 | if (copy_from_user(dst, src, size)) | |
300 | return -EFAULT; | |
301 | return 0; | |
302 | } | |
303 | ||
98a23609 | 304 | bool probe_kernel_read_allowed(const void *unsafe_src, size_t size); |
eab0c608 | 305 | |
f29c5041 | 306 | extern long probe_kernel_read(void *dst, const void *src, size_t size); |
3d708182 MH |
307 | extern long probe_user_read(void *dst, const void __user *src, size_t size); |
308 | ||
f29c5041 | 309 | extern long notrace probe_kernel_write(void *dst, const void *src, size_t size); |
1d1585ca | 310 | extern long notrace probe_user_write(void __user *dst, const void *src, size_t size); |
1d1585ca | 311 | |
c4cb1644 CH |
312 | long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, |
313 | long count); | |
eab0c608 | 314 | |
bd88bb5d CH |
315 | long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr, |
316 | long count); | |
02dddb16 | 317 | long strnlen_user_nofault(const void __user *unsafe_addr, long count); |
1a6877b9 | 318 | |
0ab32b6f AM |
319 | /** |
320 | * probe_kernel_address(): safely attempt to read from a location | |
321 | * @addr: address to read from | |
322 | * @retval: read into this variable | |
323 | * | |
324 | * Returns 0 on success, or -EFAULT. | |
325 | */ | |
326 | #define probe_kernel_address(addr, retval) \ | |
327 | probe_kernel_read(&retval, addr, sizeof(retval)) | |
328 | ||
5b24a7a2 | 329 | #ifndef user_access_begin |
594cc251 | 330 | #define user_access_begin(ptr,len) access_ok(ptr, len) |
5b24a7a2 | 331 | #define user_access_end() do { } while (0) |
c512c691 LT |
332 | #define unsafe_op_wrap(op, err) do { if (unlikely(op)) goto err; } while (0) |
333 | #define unsafe_get_user(x,p,e) unsafe_op_wrap(__get_user(x,p),e) | |
334 | #define unsafe_put_user(x,p,e) unsafe_op_wrap(__put_user(x,p),e) | |
335 | #define unsafe_copy_to_user(d,s,l,e) unsafe_op_wrap(__copy_to_user(d,s,l),e) | |
e74deb11 PZ |
336 | static inline unsigned long user_access_save(void) { return 0UL; } |
337 | static inline void user_access_restore(unsigned long flags) { } | |
5b24a7a2 | 338 | #endif |
999a2289 CL |
339 | #ifndef user_write_access_begin |
340 | #define user_write_access_begin user_access_begin | |
341 | #define user_write_access_end user_access_end | |
342 | #endif | |
343 | #ifndef user_read_access_begin | |
344 | #define user_read_access_begin user_access_begin | |
345 | #define user_read_access_end user_access_end | |
346 | #endif | |
5b24a7a2 | 347 | |
b394d468 | 348 | #ifdef CONFIG_HARDENED_USERCOPY |
afcc90f8 KC |
349 | void usercopy_warn(const char *name, const char *detail, bool to_user, |
350 | unsigned long offset, unsigned long len); | |
b394d468 KC |
351 | void __noreturn usercopy_abort(const char *name, const char *detail, |
352 | bool to_user, unsigned long offset, | |
353 | unsigned long len); | |
354 | #endif | |
355 | ||
c22ce143 | 356 | #endif /* __LINUX_UACCESS_H__ */ |