1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3  *	Berkeley style UIO structures	-	Alan Cox 1994.
4  */
5 #ifndef __LINUX_UIO_H
6 #define __LINUX_UIO_H
7 
8 #include <linux/kernel.h>
9 #include <linux/thread_info.h>
10 #include <linux/mm_types.h>
11 #include <uapi/linux/uio.h>
12 
13 struct page;
14 struct pipe_inode_info;
15 
16 struct kvec {
17 	void *iov_base; /* and that should *never* hold a userland pointer */
18 	size_t iov_len;
19 };
20 
21 enum iter_type {
22 	/* iter types */
23 	ITER_IOVEC,
24 	ITER_KVEC,
25 	ITER_BVEC,
26 	ITER_PIPE,
27 	ITER_XARRAY,
28 	ITER_DISCARD,
29 	ITER_UBUF,
30 };
31 
32 struct iov_iter_state {
33 	size_t iov_offset;
34 	size_t count;
35 	unsigned long nr_segs;
36 };
37 
38 struct iov_iter {
39 	u8 iter_type;
40 	bool nofault;
41 	bool data_source;
42 	bool user_backed;
43 	union {
44 		size_t iov_offset;
45 		int last_offset;
46 	};
47 	size_t count;
48 	union {
49 		const struct iovec *iov;
50 		const struct kvec *kvec;
51 		const struct bio_vec *bvec;
52 		struct xarray *xarray;
53 		struct pipe_inode_info *pipe;
54 		void __user *ubuf;
55 	};
56 	union {
57 		unsigned long nr_segs;
58 		struct {
59 			unsigned int head;
60 			unsigned int start_head;
61 		};
62 		loff_t xarray_start;
63 	};
64 };
65 
iov_iter_type(const struct iov_iter * i)66 static inline enum iter_type iov_iter_type(const struct iov_iter *i)
67 {
68 	return i->iter_type;
69 }
70 
iov_iter_save_state(struct iov_iter * iter,struct iov_iter_state * state)71 static inline void iov_iter_save_state(struct iov_iter *iter,
72 				       struct iov_iter_state *state)
73 {
74 	state->iov_offset = iter->iov_offset;
75 	state->count = iter->count;
76 	state->nr_segs = iter->nr_segs;
77 }
78 
iter_is_ubuf(const struct iov_iter * i)79 static inline bool iter_is_ubuf(const struct iov_iter *i)
80 {
81 	return iov_iter_type(i) == ITER_UBUF;
82 }
83 
iter_is_iovec(const struct iov_iter * i)84 static inline bool iter_is_iovec(const struct iov_iter *i)
85 {
86 	return iov_iter_type(i) == ITER_IOVEC;
87 }
88 
iov_iter_is_kvec(const struct iov_iter * i)89 static inline bool iov_iter_is_kvec(const struct iov_iter *i)
90 {
91 	return iov_iter_type(i) == ITER_KVEC;
92 }
93 
iov_iter_is_bvec(const struct iov_iter * i)94 static inline bool iov_iter_is_bvec(const struct iov_iter *i)
95 {
96 	return iov_iter_type(i) == ITER_BVEC;
97 }
98 
iov_iter_is_pipe(const struct iov_iter * i)99 static inline bool iov_iter_is_pipe(const struct iov_iter *i)
100 {
101 	return iov_iter_type(i) == ITER_PIPE;
102 }
103 
iov_iter_is_discard(const struct iov_iter * i)104 static inline bool iov_iter_is_discard(const struct iov_iter *i)
105 {
106 	return iov_iter_type(i) == ITER_DISCARD;
107 }
108 
iov_iter_is_xarray(const struct iov_iter * i)109 static inline bool iov_iter_is_xarray(const struct iov_iter *i)
110 {
111 	return iov_iter_type(i) == ITER_XARRAY;
112 }
113 
iov_iter_rw(const struct iov_iter * i)114 static inline unsigned char iov_iter_rw(const struct iov_iter *i)
115 {
116 	return i->data_source ? WRITE : READ;
117 }
118 
user_backed_iter(const struct iov_iter * i)119 static inline bool user_backed_iter(const struct iov_iter *i)
120 {
121 	return i->user_backed;
122 }
123 
124 /*
125  * Total number of bytes covered by an iovec.
126  *
127  * NOTE that it is not safe to use this function until all the iovec's
128  * segment lengths have been validated.  Because the individual lengths can
129  * overflow a size_t when added together.
130  */
iov_length(const struct iovec * iov,unsigned long nr_segs)131 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
132 {
133 	unsigned long seg;
134 	size_t ret = 0;
135 
136 	for (seg = 0; seg < nr_segs; seg++)
137 		ret += iov[seg].iov_len;
138 	return ret;
139 }
140 
iov_iter_iovec(const struct iov_iter * iter)141 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
142 {
143 	return (struct iovec) {
144 		.iov_base = iter->iov->iov_base + iter->iov_offset,
145 		.iov_len = min(iter->count,
146 			       iter->iov->iov_len - iter->iov_offset),
147 	};
148 }
149 
150 size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
151 				  size_t bytes, struct iov_iter *i);
152 void iov_iter_advance(struct iov_iter *i, size_t bytes);
153 void iov_iter_revert(struct iov_iter *i, size_t bytes);
154 size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
155 size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
156 size_t iov_iter_single_seg_count(const struct iov_iter *i);
157 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
158 			 struct iov_iter *i);
159 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
160 			 struct iov_iter *i);
161 
162 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
163 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
164 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
165 
copy_folio_to_iter(struct folio * folio,size_t offset,size_t bytes,struct iov_iter * i)166 static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
167 		size_t bytes, struct iov_iter *i)
168 {
169 	return copy_page_to_iter(&folio->page, offset, bytes, i);
170 }
171 
172 static __always_inline __must_check
copy_to_iter(const void * addr,size_t bytes,struct iov_iter * i)173 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
174 {
175 	if (check_copy_size(addr, bytes, true))
176 		return _copy_to_iter(addr, bytes, i);
177 	return 0;
178 }
179 
180 static __always_inline __must_check
copy_from_iter(void * addr,size_t bytes,struct iov_iter * i)181 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
182 {
183 	if (check_copy_size(addr, bytes, false))
184 		return _copy_from_iter(addr, bytes, i);
185 	return 0;
186 }
187 
188 static __always_inline __must_check
copy_from_iter_full(void * addr,size_t bytes,struct iov_iter * i)189 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
190 {
191 	size_t copied = copy_from_iter(addr, bytes, i);
192 	if (likely(copied == bytes))
193 		return true;
194 	iov_iter_revert(i, copied);
195 	return false;
196 }
197 
198 static __always_inline __must_check
copy_from_iter_nocache(void * addr,size_t bytes,struct iov_iter * i)199 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
200 {
201 	if (check_copy_size(addr, bytes, false))
202 		return _copy_from_iter_nocache(addr, bytes, i);
203 	return 0;
204 }
205 
206 static __always_inline __must_check
copy_from_iter_full_nocache(void * addr,size_t bytes,struct iov_iter * i)207 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
208 {
209 	size_t copied = copy_from_iter_nocache(addr, bytes, i);
210 	if (likely(copied == bytes))
211 		return true;
212 	iov_iter_revert(i, copied);
213 	return false;
214 }
215 
216 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
217 /*
218  * Note, users like pmem that depend on the stricter semantics of
219  * _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for
220  * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
221  * destination is flushed from the cache on return.
222  */
223 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
224 #else
225 #define _copy_from_iter_flushcache _copy_from_iter_nocache
226 #endif
227 
228 #ifdef CONFIG_ARCH_HAS_COPY_MC
229 size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
230 #else
231 #define _copy_mc_to_iter _copy_to_iter
232 #endif
233 
234 size_t iov_iter_zero(size_t bytes, struct iov_iter *);
235 bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
236 			unsigned len_mask);
237 unsigned long iov_iter_alignment(const struct iov_iter *i);
238 unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
239 void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
240 			unsigned long nr_segs, size_t count);
241 void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
242 			unsigned long nr_segs, size_t count);
243 void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
244 			unsigned long nr_segs, size_t count);
245 void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
246 			size_t count);
247 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
248 void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
249 		     loff_t start, size_t count);
250 ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages,
251 			size_t maxsize, unsigned maxpages, size_t *start);
252 ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages,
253 			size_t maxsize, size_t *start);
254 int iov_iter_npages(const struct iov_iter *i, int maxpages);
255 void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state);
256 
257 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
258 
iov_iter_count(const struct iov_iter * i)259 static inline size_t iov_iter_count(const struct iov_iter *i)
260 {
261 	return i->count;
262 }
263 
264 /*
265  * Cap the iov_iter by given limit; note that the second argument is
266  * *not* the new size - it's upper limit for such.  Passing it a value
267  * greater than the amount of data in iov_iter is fine - it'll just do
268  * nothing in that case.
269  */
iov_iter_truncate(struct iov_iter * i,u64 count)270 static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
271 {
272 	/*
273 	 * count doesn't have to fit in size_t - comparison extends both
274 	 * operands to u64 here and any value that would be truncated by
275 	 * conversion in assignement is by definition greater than all
276 	 * values of size_t, including old i->count.
277 	 */
278 	if (i->count > count)
279 		i->count = count;
280 }
281 
282 /*
283  * reexpand a previously truncated iterator; count must be no more than how much
284  * we had shrunk it.
285  */
iov_iter_reexpand(struct iov_iter * i,size_t count)286 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
287 {
288 	i->count = count;
289 }
290 
291 static inline int
iov_iter_npages_cap(struct iov_iter * i,int maxpages,size_t max_bytes)292 iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes)
293 {
294 	size_t shorted = 0;
295 	int npages;
296 
297 	if (iov_iter_count(i) > max_bytes) {
298 		shorted = iov_iter_count(i) - max_bytes;
299 		iov_iter_truncate(i, max_bytes);
300 	}
301 	npages = iov_iter_npages(i, maxpages);
302 	if (shorted)
303 		iov_iter_reexpand(i, iov_iter_count(i) + shorted);
304 
305 	return npages;
306 }
307 
308 struct csum_state {
309 	__wsum csum;
310 	size_t off;
311 };
312 
313 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csstate, struct iov_iter *i);
314 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
315 
316 static __always_inline __must_check
csum_and_copy_from_iter_full(void * addr,size_t bytes,__wsum * csum,struct iov_iter * i)317 bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
318 				  __wsum *csum, struct iov_iter *i)
319 {
320 	size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
321 	if (likely(copied == bytes))
322 		return true;
323 	iov_iter_revert(i, copied);
324 	return false;
325 }
326 size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
327 		struct iov_iter *i);
328 
329 struct iovec *iovec_from_user(const struct iovec __user *uvector,
330 		unsigned long nr_segs, unsigned long fast_segs,
331 		struct iovec *fast_iov, bool compat);
332 ssize_t import_iovec(int type, const struct iovec __user *uvec,
333 		 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
334 		 struct iov_iter *i);
335 ssize_t __import_iovec(int type, const struct iovec __user *uvec,
336 		 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
337 		 struct iov_iter *i, bool compat);
338 int import_single_range(int type, void __user *buf, size_t len,
339 		 struct iovec *iov, struct iov_iter *i);
340 
iov_iter_ubuf(struct iov_iter * i,unsigned int direction,void __user * buf,size_t count)341 static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
342 			void __user *buf, size_t count)
343 {
344 	WARN_ON(direction & ~(READ | WRITE));
345 	*i = (struct iov_iter) {
346 		.iter_type = ITER_UBUF,
347 		.user_backed = true,
348 		.data_source = direction,
349 		.ubuf = buf,
350 		.count = count
351 	};
352 }
353 
354 #endif
355