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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __LINUX_UACCESS_H__
3#define __LINUX_UACCESS_H__
4
5#include <linux/fault-inject-usercopy.h>
6#include <linux/instrumented.h>
7#include <linux/minmax.h>
8#include <linux/sched.h>
9#include <linux/thread_info.h>
10
11#include <asm/uaccess.h>
12
13#ifdef CONFIG_SET_FS
14/*
15 * Force the uaccess routines to be wired up for actual userspace access,
16 * overriding any possible set_fs(KERNEL_DS) still lingering around. Undone
17 * using force_uaccess_end below.
18 */
19static inline mm_segment_t force_uaccess_begin(void)
20{
21 mm_segment_t fs = get_fs();
22
23 set_fs(USER_DS);
24 return fs;
25}
26
27static inline void force_uaccess_end(mm_segment_t oldfs)
28{
29 set_fs(oldfs);
30}
31#else /* CONFIG_SET_FS */
32typedef struct {
33 /* empty dummy */
34} mm_segment_t;
35
36#ifndef TASK_SIZE_MAX
37#define TASK_SIZE_MAX TASK_SIZE
38#endif
39
40#define uaccess_kernel() (false)
41#define user_addr_max() (TASK_SIZE_MAX)
42
43static inline mm_segment_t force_uaccess_begin(void)
44{
45 return (mm_segment_t) { };
46}
47
48static inline void force_uaccess_end(mm_segment_t oldfs)
49{
50}
51#endif /* CONFIG_SET_FS */
52
53/*
54 * Architectures should provide two primitives (raw_copy_{to,from}_user())
55 * and get rid of their private instances of copy_{to,from}_user() and
56 * __copy_{to,from}_user{,_inatomic}().
57 *
58 * raw_copy_{to,from}_user(to, from, size) should copy up to size bytes and
59 * return the amount left to copy. They should assume that access_ok() has
60 * already been checked (and succeeded); they should *not* zero-pad anything.
61 * No KASAN or object size checks either - those belong here.
62 *
63 * Both of these functions should attempt to copy size bytes starting at from
64 * into the area starting at to. They must not fetch or store anything
65 * outside of those areas. Return value must be between 0 (everything
66 * copied successfully) and size (nothing copied).
67 *
68 * If raw_copy_{to,from}_user(to, from, size) returns N, size - N bytes starting
69 * at to must become equal to the bytes fetched from the corresponding area
70 * starting at from. All data past to + size - N must be left unmodified.
71 *
72 * If copying succeeds, the return value must be 0. If some data cannot be
73 * fetched, it is permitted to copy less than had been fetched; the only
74 * hard requirement is that not storing anything at all (i.e. returning size)
75 * should happen only when nothing could be copied. In other words, you don't
76 * have to squeeze as much as possible - it is allowed, but not necessary.
77 *
78 * For raw_copy_from_user() to always points to kernel memory and no faults
79 * on store should happen. Interpretation of from is affected by set_fs().
80 * For raw_copy_to_user() it's the other way round.
81 *
82 * Both can be inlined - it's up to architectures whether it wants to bother
83 * with that. They should not be used directly; they are used to implement
84 * the 6 functions (copy_{to,from}_user(), __copy_{to,from}_user_inatomic())
85 * that are used instead. Out of those, __... ones are inlined. Plain
86 * copy_{to,from}_user() might or might not be inlined. If you want them
87 * inlined, have asm/uaccess.h define INLINE_COPY_{TO,FROM}_USER.
88 *
89 * NOTE: only copy_from_user() zero-pads the destination in case of short copy.
90 * Neither __copy_from_user() nor __copy_from_user_inatomic() zero anything
91 * at all; their callers absolutely must check the return value.
92 *
93 * Biarch ones should also provide raw_copy_in_user() - similar to the above,
94 * but both source and destination are __user pointers (affected by set_fs()
95 * as usual) and both source and destination can trigger faults.
96 */
97
98static __always_inline __must_check unsigned long
99__copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
100{
101 instrument_copy_from_user(to, from, n);
102 check_object_size(to, n, false);
103 return raw_copy_from_user(to, from, n);
104}
105
106static __always_inline __must_check unsigned long
107__copy_from_user(void *to, const void __user *from, unsigned long n)
108{
109 might_fault();
110 if (should_fail_usercopy())
111 return n;
112 instrument_copy_from_user(to, from, n);
113 check_object_size(to, n, false);
114 return raw_copy_from_user(to, from, n);
115}
116
117/**
118 * __copy_to_user_inatomic: - Copy a block of data into user space, with less checking.
119 * @to: Destination address, in user space.
120 * @from: Source address, in kernel space.
121 * @n: Number of bytes to copy.
122 *
123 * Context: User context only.
124 *
125 * Copy data from kernel space to user space. Caller must check
126 * the specified block with access_ok() before calling this function.
127 * The caller should also make sure he pins the user space address
128 * so that we don't result in page fault and sleep.
129 */
130static __always_inline __must_check unsigned long
131__copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
132{
133 if (should_fail_usercopy())
134 return n;
135 instrument_copy_to_user(to, from, n);
136 check_object_size(from, n, true);
137 return raw_copy_to_user(to, from, n);
138}
139
140static __always_inline __must_check unsigned long
141__copy_to_user(void __user *to, const void *from, unsigned long n)
142{
143 might_fault();
144 if (should_fail_usercopy())
145 return n;
146 instrument_copy_to_user(to, from, n);
147 check_object_size(from, n, true);
148 return raw_copy_to_user(to, from, n);
149}
150
151#ifdef INLINE_COPY_FROM_USER
152static inline __must_check unsigned long
153_copy_from_user(void *to, const void __user *from, unsigned long n)
154{
155 unsigned long res = n;
156 might_fault();
157 if (!should_fail_usercopy() && likely(access_ok(from, n))) {
158 instrument_copy_from_user(to, from, n);
159 res = raw_copy_from_user(to, from, n);
160 }
161 if (unlikely(res))
162 memset(to + (n - res), 0, res);
163 return res;
164}
165#else
166extern __must_check unsigned long
167_copy_from_user(void *, const void __user *, unsigned long);
168#endif
169
170#ifdef INLINE_COPY_TO_USER
171static inline __must_check unsigned long
172_copy_to_user(void __user *to, const void *from, unsigned long n)
173{
174 might_fault();
175 if (should_fail_usercopy())
176 return n;
177 if (access_ok(to, n)) {
178 instrument_copy_to_user(to, from, n);
179 n = raw_copy_to_user(to, from, n);
180 }
181 return n;
182}
183#else
184extern __must_check unsigned long
185_copy_to_user(void __user *, const void *, unsigned long);
186#endif
187
188static __always_inline unsigned long __must_check
189copy_from_user(void *to, const void __user *from, unsigned long n)
190{
191 if (likely(check_copy_size(to, n, false)))
192 n = _copy_from_user(to, from, n);
193 return n;
194}
195
196static __always_inline unsigned long __must_check
197copy_to_user(void __user *to, const void *from, unsigned long n)
198{
199 if (likely(check_copy_size(from, n, true)))
200 n = _copy_to_user(to, from, n);
201 return n;
202}
203#ifdef CONFIG_COMPAT
204static __always_inline unsigned long __must_check
205copy_in_user(void __user *to, const void __user *from, unsigned long n)
206{
207 might_fault();
208 if (access_ok(to, n) && access_ok(from, n))
209 n = raw_copy_in_user(to, from, n);
210 return n;
211}
212#endif
213
214#ifndef copy_mc_to_kernel
215/*
216 * Without arch opt-in this generic copy_mc_to_kernel() will not handle
217 * #MC (or arch equivalent) during source read.
218 */
219static inline unsigned long __must_check
220copy_mc_to_kernel(void *dst, const void *src, size_t cnt)
221{
222 memcpy(dst, src, cnt);
223 return 0;
224}
225#endif
226
227static __always_inline void pagefault_disabled_inc(void)
228{
229 current->pagefault_disabled++;
230}
231
232static __always_inline void pagefault_disabled_dec(void)
233{
234 current->pagefault_disabled--;
235}
236
237/*
238 * These routines enable/disable the pagefault handler. If disabled, it will
239 * not take any locks and go straight to the fixup table.
240 *
241 * User access methods will not sleep when called from a pagefault_disabled()
242 * environment.
243 */
244static inline void pagefault_disable(void)
245{
246 pagefault_disabled_inc();
247 /*
248 * make sure to have issued the store before a pagefault
249 * can hit.
250 */
251 barrier();
252}
253
254static inline void pagefault_enable(void)
255{
256 /*
257 * make sure to issue those last loads/stores before enabling
258 * the pagefault handler again.
259 */
260 barrier();
261 pagefault_disabled_dec();
262}
263
264/*
265 * Is the pagefault handler disabled? If so, user access methods will not sleep.
266 */
267static inline bool pagefault_disabled(void)
268{
269 return current->pagefault_disabled != 0;
270}
271
272/*
273 * The pagefault handler is in general disabled by pagefault_disable() or
274 * when in irq context (via in_atomic()).
275 *
276 * This function should only be used by the fault handlers. Other users should
277 * stick to pagefault_disabled().
278 * Please NEVER use preempt_disable() to disable the fault handler. With
279 * !CONFIG_PREEMPT_COUNT, this is like a NOP. So the handler won't be disabled.
280 * in_atomic() will report different values based on !CONFIG_PREEMPT_COUNT.
281 */
282#define faulthandler_disabled() (pagefault_disabled() || in_atomic())
283
284#ifndef ARCH_HAS_NOCACHE_UACCESS
285
286static inline __must_check unsigned long
287__copy_from_user_inatomic_nocache(void *to, const void __user *from,
288 unsigned long n)
289{
290 return __copy_from_user_inatomic(to, from, n);
291}
292
293#endif /* ARCH_HAS_NOCACHE_UACCESS */
294
295extern __must_check int check_zeroed_user(const void __user *from, size_t size);
296
297/**
298 * copy_struct_from_user: copy a struct from userspace
299 * @dst: Destination address, in kernel space. This buffer must be @ksize
300 * bytes long.
301 * @ksize: Size of @dst struct.
302 * @src: Source address, in userspace.
303 * @usize: (Alleged) size of @src struct.
304 *
305 * Copies a struct from userspace to kernel space, in a way that guarantees
306 * backwards-compatibility for struct syscall arguments (as long as future
307 * struct extensions are made such that all new fields are *appended* to the
308 * old struct, and zeroed-out new fields have the same meaning as the old
309 * struct).
310 *
311 * @ksize is just sizeof(*dst), and @usize should've been passed by userspace.
312 * The recommended usage is something like the following:
313 *
314 * SYSCALL_DEFINE2(foobar, const struct foo __user *, uarg, size_t, usize)
315 * {
316 * int err;
317 * struct foo karg = {};
318 *
319 * if (usize > PAGE_SIZE)
320 * return -E2BIG;
321 * if (usize < FOO_SIZE_VER0)
322 * return -EINVAL;
323 *
324 * err = copy_struct_from_user(&karg, sizeof(karg), uarg, usize);
325 * if (err)
326 * return err;
327 *
328 * // ...
329 * }
330 *
331 * There are three cases to consider:
332 * * If @usize == @ksize, then it's copied verbatim.
333 * * If @usize < @ksize, then the userspace has passed an old struct to a
334 * newer kernel. The rest of the trailing bytes in @dst (@ksize - @usize)
335 * are to be zero-filled.
336 * * If @usize > @ksize, then the userspace has passed a new struct to an
337 * older kernel. The trailing bytes unknown to the kernel (@usize - @ksize)
338 * are checked to ensure they are zeroed, otherwise -E2BIG is returned.
339 *
340 * Returns (in all cases, some data may have been copied):
341 * * -E2BIG: (@usize > @ksize) and there are non-zero trailing bytes in @src.
342 * * -EFAULT: access to userspace failed.
343 */
344static __always_inline __must_check int
345copy_struct_from_user(void *dst, size_t ksize, const void __user *src,
346 size_t usize)
347{
348 size_t size = min(ksize, usize);
349 size_t rest = max(ksize, usize) - size;
350
351 /* Deal with trailing bytes. */
352 if (usize < ksize) {
353 memset(dst + size, 0, rest);
354 } else if (usize > ksize) {
355 int ret = check_zeroed_user(src + size, rest);
356 if (ret <= 0)
357 return ret ?: -E2BIG;
358 }
359 /* Copy the interoperable parts of the struct. */
360 if (copy_from_user(dst, src, size))
361 return -EFAULT;
362 return 0;
363}
364
365bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size);
366
367long copy_from_kernel_nofault(void *dst, const void *src, size_t size);
368long notrace copy_to_kernel_nofault(void *dst, const void *src, size_t size);
369
370long copy_from_user_nofault(void *dst, const void __user *src, size_t size);
371long notrace copy_to_user_nofault(void __user *dst, const void *src,
372 size_t size);
373
374long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr,
375 long count);
376
377long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
378 long count);
379long strnlen_user_nofault(const void __user *unsafe_addr, long count);
380
381/**
382 * get_kernel_nofault(): safely attempt to read from a location
383 * @val: read into this variable
384 * @ptr: address to read from
385 *
386 * Returns 0 on success, or -EFAULT.
387 */
388#define get_kernel_nofault(val, ptr) ({ \
389 const typeof(val) *__gk_ptr = (ptr); \
390 copy_from_kernel_nofault(&(val), __gk_ptr, sizeof(val));\
391})
392
393#ifndef user_access_begin
394#define user_access_begin(ptr,len) access_ok(ptr, len)
395#define user_access_end() do { } while (0)
396#define unsafe_op_wrap(op, err) do { if (unlikely(op)) goto err; } while (0)
397#define unsafe_get_user(x,p,e) unsafe_op_wrap(__get_user(x,p),e)
398#define unsafe_put_user(x,p,e) unsafe_op_wrap(__put_user(x,p),e)
399#define unsafe_copy_to_user(d,s,l,e) unsafe_op_wrap(__copy_to_user(d,s,l),e)
400#define unsafe_copy_from_user(d,s,l,e) unsafe_op_wrap(__copy_from_user(d,s,l),e)
401static inline unsigned long user_access_save(void) { return 0UL; }
402static inline void user_access_restore(unsigned long flags) { }
403#endif
404#ifndef user_write_access_begin
405#define user_write_access_begin user_access_begin
406#define user_write_access_end user_access_end
407#endif
408#ifndef user_read_access_begin
409#define user_read_access_begin user_access_begin
410#define user_read_access_end user_access_end
411#endif
412
413#ifdef CONFIG_HARDENED_USERCOPY
414void usercopy_warn(const char *name, const char *detail, bool to_user,
415 unsigned long offset, unsigned long len);
416void __noreturn usercopy_abort(const char *name, const char *detail,
417 bool to_user, unsigned long offset,
418 unsigned long len);
419#endif
420
421#endif /* __LINUX_UACCESS_H__ */
1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __LINUX_UACCESS_H__
3#define __LINUX_UACCESS_H__
4
5#include <linux/fault-inject-usercopy.h>
6#include <linux/instrumented.h>
7#include <linux/minmax.h>
8#include <linux/sched.h>
9#include <linux/thread_info.h>
10
11#include <asm/uaccess.h>
12
13/*
14 * Architectures that support memory tagging (assigning tags to memory regions,
15 * embedding these tags into addresses that point to these memory regions, and
16 * checking that the memory and the pointer tags match on memory accesses)
17 * redefine this macro to strip tags from pointers.
18 *
19 * Passing down mm_struct allows to define untagging rules on per-process
20 * basis.
21 *
22 * It's defined as noop for architectures that don't support memory tagging.
23 */
24#ifndef untagged_addr
25#define untagged_addr(addr) (addr)
26#endif
27
28#ifndef untagged_addr_remote
29#define untagged_addr_remote(mm, addr) ({ \
30 mmap_assert_locked(mm); \
31 untagged_addr(addr); \
32})
33#endif
34
35/*
36 * Architectures should provide two primitives (raw_copy_{to,from}_user())
37 * and get rid of their private instances of copy_{to,from}_user() and
38 * __copy_{to,from}_user{,_inatomic}().
39 *
40 * raw_copy_{to,from}_user(to, from, size) should copy up to size bytes and
41 * return the amount left to copy. They should assume that access_ok() has
42 * already been checked (and succeeded); they should *not* zero-pad anything.
43 * No KASAN or object size checks either - those belong here.
44 *
45 * Both of these functions should attempt to copy size bytes starting at from
46 * into the area starting at to. They must not fetch or store anything
47 * outside of those areas. Return value must be between 0 (everything
48 * copied successfully) and size (nothing copied).
49 *
50 * If raw_copy_{to,from}_user(to, from, size) returns N, size - N bytes starting
51 * at to must become equal to the bytes fetched from the corresponding area
52 * starting at from. All data past to + size - N must be left unmodified.
53 *
54 * If copying succeeds, the return value must be 0. If some data cannot be
55 * fetched, it is permitted to copy less than had been fetched; the only
56 * hard requirement is that not storing anything at all (i.e. returning size)
57 * should happen only when nothing could be copied. In other words, you don't
58 * have to squeeze as much as possible - it is allowed, but not necessary.
59 *
60 * For raw_copy_from_user() to always points to kernel memory and no faults
61 * on store should happen. Interpretation of from is affected by set_fs().
62 * For raw_copy_to_user() it's the other way round.
63 *
64 * Both can be inlined - it's up to architectures whether it wants to bother
65 * with that. They should not be used directly; they are used to implement
66 * the 6 functions (copy_{to,from}_user(), __copy_{to,from}_user_inatomic())
67 * that are used instead. Out of those, __... ones are inlined. Plain
68 * copy_{to,from}_user() might or might not be inlined. If you want them
69 * inlined, have asm/uaccess.h define INLINE_COPY_{TO,FROM}_USER.
70 *
71 * NOTE: only copy_from_user() zero-pads the destination in case of short copy.
72 * Neither __copy_from_user() nor __copy_from_user_inatomic() zero anything
73 * at all; their callers absolutely must check the return value.
74 *
75 * Biarch ones should also provide raw_copy_in_user() - similar to the above,
76 * but both source and destination are __user pointers (affected by set_fs()
77 * as usual) and both source and destination can trigger faults.
78 */
79
80static __always_inline __must_check unsigned long
81__copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
82{
83 unsigned long res;
84
85 instrument_copy_from_user_before(to, from, n);
86 check_object_size(to, n, false);
87 res = raw_copy_from_user(to, from, n);
88 instrument_copy_from_user_after(to, from, n, res);
89 return res;
90}
91
92static __always_inline __must_check unsigned long
93__copy_from_user(void *to, const void __user *from, unsigned long n)
94{
95 unsigned long res;
96
97 might_fault();
98 instrument_copy_from_user_before(to, from, n);
99 if (should_fail_usercopy())
100 return n;
101 check_object_size(to, n, false);
102 res = raw_copy_from_user(to, from, n);
103 instrument_copy_from_user_after(to, from, n, res);
104 return res;
105}
106
107/**
108 * __copy_to_user_inatomic: - Copy a block of data into user space, with less checking.
109 * @to: Destination address, in user space.
110 * @from: Source address, in kernel space.
111 * @n: Number of bytes to copy.
112 *
113 * Context: User context only.
114 *
115 * Copy data from kernel space to user space. Caller must check
116 * the specified block with access_ok() before calling this function.
117 * The caller should also make sure he pins the user space address
118 * so that we don't result in page fault and sleep.
119 */
120static __always_inline __must_check unsigned long
121__copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
122{
123 if (should_fail_usercopy())
124 return n;
125 instrument_copy_to_user(to, from, n);
126 check_object_size(from, n, true);
127 return raw_copy_to_user(to, from, n);
128}
129
130static __always_inline __must_check unsigned long
131__copy_to_user(void __user *to, const void *from, unsigned long n)
132{
133 might_fault();
134 if (should_fail_usercopy())
135 return n;
136 instrument_copy_to_user(to, from, n);
137 check_object_size(from, n, true);
138 return raw_copy_to_user(to, from, n);
139}
140
141#ifdef INLINE_COPY_FROM_USER
142static inline __must_check unsigned long
143_copy_from_user(void *to, const void __user *from, unsigned long n)
144{
145 unsigned long res = n;
146 might_fault();
147 if (!should_fail_usercopy() && likely(access_ok(from, n))) {
148 instrument_copy_from_user_before(to, from, n);
149 res = raw_copy_from_user(to, from, n);
150 instrument_copy_from_user_after(to, from, n, res);
151 }
152 if (unlikely(res))
153 memset(to + (n - res), 0, res);
154 return res;
155}
156#else
157extern __must_check unsigned long
158_copy_from_user(void *, const void __user *, unsigned long);
159#endif
160
161#ifdef INLINE_COPY_TO_USER
162static inline __must_check unsigned long
163_copy_to_user(void __user *to, const void *from, unsigned long n)
164{
165 might_fault();
166 if (should_fail_usercopy())
167 return n;
168 if (access_ok(to, n)) {
169 instrument_copy_to_user(to, from, n);
170 n = raw_copy_to_user(to, from, n);
171 }
172 return n;
173}
174#else
175extern __must_check unsigned long
176_copy_to_user(void __user *, const void *, unsigned long);
177#endif
178
179static __always_inline unsigned long __must_check
180copy_from_user(void *to, const void __user *from, unsigned long n)
181{
182 if (check_copy_size(to, n, false))
183 n = _copy_from_user(to, from, n);
184 return n;
185}
186
187static __always_inline unsigned long __must_check
188copy_to_user(void __user *to, const void *from, unsigned long n)
189{
190 if (check_copy_size(from, n, true))
191 n = _copy_to_user(to, from, n);
192 return n;
193}
194
195#ifndef copy_mc_to_kernel
196/*
197 * Without arch opt-in this generic copy_mc_to_kernel() will not handle
198 * #MC (or arch equivalent) during source read.
199 */
200static inline unsigned long __must_check
201copy_mc_to_kernel(void *dst, const void *src, size_t cnt)
202{
203 memcpy(dst, src, cnt);
204 return 0;
205}
206#endif
207
208static __always_inline void pagefault_disabled_inc(void)
209{
210 current->pagefault_disabled++;
211}
212
213static __always_inline void pagefault_disabled_dec(void)
214{
215 current->pagefault_disabled--;
216}
217
218/*
219 * These routines enable/disable the pagefault handler. If disabled, it will
220 * not take any locks and go straight to the fixup table.
221 *
222 * User access methods will not sleep when called from a pagefault_disabled()
223 * environment.
224 */
225static inline void pagefault_disable(void)
226{
227 pagefault_disabled_inc();
228 /*
229 * make sure to have issued the store before a pagefault
230 * can hit.
231 */
232 barrier();
233}
234
235static inline void pagefault_enable(void)
236{
237 /*
238 * make sure to issue those last loads/stores before enabling
239 * the pagefault handler again.
240 */
241 barrier();
242 pagefault_disabled_dec();
243}
244
245/*
246 * Is the pagefault handler disabled? If so, user access methods will not sleep.
247 */
248static inline bool pagefault_disabled(void)
249{
250 return current->pagefault_disabled != 0;
251}
252
253/*
254 * The pagefault handler is in general disabled by pagefault_disable() or
255 * when in irq context (via in_atomic()).
256 *
257 * This function should only be used by the fault handlers. Other users should
258 * stick to pagefault_disabled().
259 * Please NEVER use preempt_disable() to disable the fault handler. With
260 * !CONFIG_PREEMPT_COUNT, this is like a NOP. So the handler won't be disabled.
261 * in_atomic() will report different values based on !CONFIG_PREEMPT_COUNT.
262 */
263#define faulthandler_disabled() (pagefault_disabled() || in_atomic())
264
265#ifndef CONFIG_ARCH_HAS_SUBPAGE_FAULTS
266
267/**
268 * probe_subpage_writeable: probe the user range for write faults at sub-page
269 * granularity (e.g. arm64 MTE)
270 * @uaddr: start of address range
271 * @size: size of address range
272 *
273 * Returns 0 on success, the number of bytes not probed on fault.
274 *
275 * It is expected that the caller checked for the write permission of each
276 * page in the range either by put_user() or GUP. The architecture port can
277 * implement a more efficient get_user() probing if the same sub-page faults
278 * are triggered by either a read or a write.
279 */
280static inline size_t probe_subpage_writeable(char __user *uaddr, size_t size)
281{
282 return 0;
283}
284
285#endif /* CONFIG_ARCH_HAS_SUBPAGE_FAULTS */
286
287#ifndef ARCH_HAS_NOCACHE_UACCESS
288
289static inline __must_check unsigned long
290__copy_from_user_inatomic_nocache(void *to, const void __user *from,
291 unsigned long n)
292{
293 return __copy_from_user_inatomic(to, from, n);
294}
295
296#endif /* ARCH_HAS_NOCACHE_UACCESS */
297
298extern __must_check int check_zeroed_user(const void __user *from, size_t size);
299
300/**
301 * copy_struct_from_user: copy a struct from userspace
302 * @dst: Destination address, in kernel space. This buffer must be @ksize
303 * bytes long.
304 * @ksize: Size of @dst struct.
305 * @src: Source address, in userspace.
306 * @usize: (Alleged) size of @src struct.
307 *
308 * Copies a struct from userspace to kernel space, in a way that guarantees
309 * backwards-compatibility for struct syscall arguments (as long as future
310 * struct extensions are made such that all new fields are *appended* to the
311 * old struct, and zeroed-out new fields have the same meaning as the old
312 * struct).
313 *
314 * @ksize is just sizeof(*dst), and @usize should've been passed by userspace.
315 * The recommended usage is something like the following:
316 *
317 * SYSCALL_DEFINE2(foobar, const struct foo __user *, uarg, size_t, usize)
318 * {
319 * int err;
320 * struct foo karg = {};
321 *
322 * if (usize > PAGE_SIZE)
323 * return -E2BIG;
324 * if (usize < FOO_SIZE_VER0)
325 * return -EINVAL;
326 *
327 * err = copy_struct_from_user(&karg, sizeof(karg), uarg, usize);
328 * if (err)
329 * return err;
330 *
331 * // ...
332 * }
333 *
334 * There are three cases to consider:
335 * * If @usize == @ksize, then it's copied verbatim.
336 * * If @usize < @ksize, then the userspace has passed an old struct to a
337 * newer kernel. The rest of the trailing bytes in @dst (@ksize - @usize)
338 * are to be zero-filled.
339 * * If @usize > @ksize, then the userspace has passed a new struct to an
340 * older kernel. The trailing bytes unknown to the kernel (@usize - @ksize)
341 * are checked to ensure they are zeroed, otherwise -E2BIG is returned.
342 *
343 * Returns (in all cases, some data may have been copied):
344 * * -E2BIG: (@usize > @ksize) and there are non-zero trailing bytes in @src.
345 * * -EFAULT: access to userspace failed.
346 */
347static __always_inline __must_check int
348copy_struct_from_user(void *dst, size_t ksize, const void __user *src,
349 size_t usize)
350{
351 size_t size = min(ksize, usize);
352 size_t rest = max(ksize, usize) - size;
353
354 /* Double check if ksize is larger than a known object size. */
355 if (WARN_ON_ONCE(ksize > __builtin_object_size(dst, 1)))
356 return -E2BIG;
357
358 /* Deal with trailing bytes. */
359 if (usize < ksize) {
360 memset(dst + size, 0, rest);
361 } else if (usize > ksize) {
362 int ret = check_zeroed_user(src + size, rest);
363 if (ret <= 0)
364 return ret ?: -E2BIG;
365 }
366 /* Copy the interoperable parts of the struct. */
367 if (copy_from_user(dst, src, size))
368 return -EFAULT;
369 return 0;
370}
371
372bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size);
373
374long copy_from_kernel_nofault(void *dst, const void *src, size_t size);
375long notrace copy_to_kernel_nofault(void *dst, const void *src, size_t size);
376
377long copy_from_user_nofault(void *dst, const void __user *src, size_t size);
378long notrace copy_to_user_nofault(void __user *dst, const void *src,
379 size_t size);
380
381long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr,
382 long count);
383
384long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
385 long count);
386long strnlen_user_nofault(const void __user *unsafe_addr, long count);
387
388#ifndef __get_kernel_nofault
389#define __get_kernel_nofault(dst, src, type, label) \
390do { \
391 type __user *p = (type __force __user *)(src); \
392 type data; \
393 if (__get_user(data, p)) \
394 goto label; \
395 *(type *)dst = data; \
396} while (0)
397
398#define __put_kernel_nofault(dst, src, type, label) \
399do { \
400 type __user *p = (type __force __user *)(dst); \
401 type data = *(type *)src; \
402 if (__put_user(data, p)) \
403 goto label; \
404} while (0)
405#endif
406
407/**
408 * get_kernel_nofault(): safely attempt to read from a location
409 * @val: read into this variable
410 * @ptr: address to read from
411 *
412 * Returns 0 on success, or -EFAULT.
413 */
414#define get_kernel_nofault(val, ptr) ({ \
415 const typeof(val) *__gk_ptr = (ptr); \
416 copy_from_kernel_nofault(&(val), __gk_ptr, sizeof(val));\
417})
418
419#ifndef user_access_begin
420#define user_access_begin(ptr,len) access_ok(ptr, len)
421#define user_access_end() do { } while (0)
422#define unsafe_op_wrap(op, err) do { if (unlikely(op)) goto err; } while (0)
423#define unsafe_get_user(x,p,e) unsafe_op_wrap(__get_user(x,p),e)
424#define unsafe_put_user(x,p,e) unsafe_op_wrap(__put_user(x,p),e)
425#define unsafe_copy_to_user(d,s,l,e) unsafe_op_wrap(__copy_to_user(d,s,l),e)
426#define unsafe_copy_from_user(d,s,l,e) unsafe_op_wrap(__copy_from_user(d,s,l),e)
427static inline unsigned long user_access_save(void) { return 0UL; }
428static inline void user_access_restore(unsigned long flags) { }
429#endif
430#ifndef user_write_access_begin
431#define user_write_access_begin user_access_begin
432#define user_write_access_end user_access_end
433#endif
434#ifndef user_read_access_begin
435#define user_read_access_begin user_access_begin
436#define user_read_access_end user_access_end
437#endif
438
439#ifdef CONFIG_HARDENED_USERCOPY
440void __noreturn usercopy_abort(const char *name, const char *detail,
441 bool to_user, unsigned long offset,
442 unsigned long len);
443#endif
444
445#endif /* __LINUX_UACCESS_H__ */