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 66 static inline enum iter_type iov_iter_type(const struct iov_iter *i) 67 { 68 return i->iter_type; 69 } 70 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 79 static inline bool iter_is_ubuf(const struct iov_iter *i) 80 { 81 return iov_iter_type(i) == ITER_UBUF; 82 } 83 84 static inline bool iter_is_iovec(const struct iov_iter *i) 85 { 86 return iov_iter_type(i) == ITER_IOVEC; 87 } 88 89 static inline bool iov_iter_is_kvec(const struct iov_iter *i) 90 { 91 return iov_iter_type(i) == ITER_KVEC; 92 } 93 94 static inline bool iov_iter_is_bvec(const struct iov_iter *i) 95 { 96 return iov_iter_type(i) == ITER_BVEC; 97 } 98 99 static inline bool iov_iter_is_pipe(const struct iov_iter *i) 100 { 101 return iov_iter_type(i) == ITER_PIPE; 102 } 103 104 static inline bool iov_iter_is_discard(const struct iov_iter *i) 105 { 106 return iov_iter_type(i) == ITER_DISCARD; 107 } 108 109 static inline bool iov_iter_is_xarray(const struct iov_iter *i) 110 { 111 return iov_iter_type(i) == ITER_XARRAY; 112 } 113 114 static inline unsigned char iov_iter_rw(const struct iov_iter *i) 115 { 116 return i->data_source ? WRITE : READ; 117 } 118 119 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 */ 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 } 140 141 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); 165 166 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 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 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 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 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 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); 258 259 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 */ 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 */ 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 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 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); 340 341 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