| 1 | // SPDX-License-Identifier: GPL-2.0-only |
| 2 | #include <crypto/hash.h> |
| 3 | #include <linux/export.h> |
| 4 | #include <linux/bvec.h> |
| 5 | #include <linux/fault-inject-usercopy.h> |
| 6 | #include <linux/uio.h> |
| 7 | #include <linux/pagemap.h> |
| 8 | #include <linux/highmem.h> |
| 9 | #include <linux/slab.h> |
| 10 | #include <linux/vmalloc.h> |
| 11 | #include <linux/splice.h> |
| 12 | #include <linux/compat.h> |
| 13 | #include <net/checksum.h> |
| 14 | #include <linux/scatterlist.h> |
| 15 | #include <linux/instrumented.h> |
| 16 | |
| 17 | #define PIPE_PARANOIA /* for now */ |
| 18 | |
| 19 | /* covers ubuf and kbuf alike */ |
| 20 | #define iterate_buf(i, n, base, len, off, __p, STEP) { \ |
| 21 | size_t __maybe_unused off = 0; \ |
| 22 | len = n; \ |
| 23 | base = __p + i->iov_offset; \ |
| 24 | len -= (STEP); \ |
| 25 | i->iov_offset += len; \ |
| 26 | n = len; \ |
| 27 | } |
| 28 | |
| 29 | /* covers iovec and kvec alike */ |
| 30 | #define iterate_iovec(i, n, base, len, off, __p, STEP) { \ |
| 31 | size_t off = 0; \ |
| 32 | size_t skip = i->iov_offset; \ |
| 33 | do { \ |
| 34 | len = min(n, __p->iov_len - skip); \ |
| 35 | if (likely(len)) { \ |
| 36 | base = __p->iov_base + skip; \ |
| 37 | len -= (STEP); \ |
| 38 | off += len; \ |
| 39 | skip += len; \ |
| 40 | n -= len; \ |
| 41 | if (skip < __p->iov_len) \ |
| 42 | break; \ |
| 43 | } \ |
| 44 | __p++; \ |
| 45 | skip = 0; \ |
| 46 | } while (n); \ |
| 47 | i->iov_offset = skip; \ |
| 48 | n = off; \ |
| 49 | } |
| 50 | |
| 51 | #define iterate_bvec(i, n, base, len, off, p, STEP) { \ |
| 52 | size_t off = 0; \ |
| 53 | unsigned skip = i->iov_offset; \ |
| 54 | while (n) { \ |
| 55 | unsigned offset = p->bv_offset + skip; \ |
| 56 | unsigned left; \ |
| 57 | void *kaddr = kmap_local_page(p->bv_page + \ |
| 58 | offset / PAGE_SIZE); \ |
| 59 | base = kaddr + offset % PAGE_SIZE; \ |
| 60 | len = min(min(n, (size_t)(p->bv_len - skip)), \ |
| 61 | (size_t)(PAGE_SIZE - offset % PAGE_SIZE)); \ |
| 62 | left = (STEP); \ |
| 63 | kunmap_local(kaddr); \ |
| 64 | len -= left; \ |
| 65 | off += len; \ |
| 66 | skip += len; \ |
| 67 | if (skip == p->bv_len) { \ |
| 68 | skip = 0; \ |
| 69 | p++; \ |
| 70 | } \ |
| 71 | n -= len; \ |
| 72 | if (left) \ |
| 73 | break; \ |
| 74 | } \ |
| 75 | i->iov_offset = skip; \ |
| 76 | n = off; \ |
| 77 | } |
| 78 | |
| 79 | #define iterate_xarray(i, n, base, len, __off, STEP) { \ |
| 80 | __label__ __out; \ |
| 81 | size_t __off = 0; \ |
| 82 | struct folio *folio; \ |
| 83 | loff_t start = i->xarray_start + i->iov_offset; \ |
| 84 | pgoff_t index = start / PAGE_SIZE; \ |
| 85 | XA_STATE(xas, i->xarray, index); \ |
| 86 | \ |
| 87 | len = PAGE_SIZE - offset_in_page(start); \ |
| 88 | rcu_read_lock(); \ |
| 89 | xas_for_each(&xas, folio, ULONG_MAX) { \ |
| 90 | unsigned left; \ |
| 91 | size_t offset; \ |
| 92 | if (xas_retry(&xas, folio)) \ |
| 93 | continue; \ |
| 94 | if (WARN_ON(xa_is_value(folio))) \ |
| 95 | break; \ |
| 96 | if (WARN_ON(folio_test_hugetlb(folio))) \ |
| 97 | break; \ |
| 98 | offset = offset_in_folio(folio, start + __off); \ |
| 99 | while (offset < folio_size(folio)) { \ |
| 100 | base = kmap_local_folio(folio, offset); \ |
| 101 | len = min(n, len); \ |
| 102 | left = (STEP); \ |
| 103 | kunmap_local(base); \ |
| 104 | len -= left; \ |
| 105 | __off += len; \ |
| 106 | n -= len; \ |
| 107 | if (left || n == 0) \ |
| 108 | goto __out; \ |
| 109 | offset += len; \ |
| 110 | len = PAGE_SIZE; \ |
| 111 | } \ |
| 112 | } \ |
| 113 | __out: \ |
| 114 | rcu_read_unlock(); \ |
| 115 | i->iov_offset += __off; \ |
| 116 | n = __off; \ |
| 117 | } |
| 118 | |
| 119 | #define __iterate_and_advance(i, n, base, len, off, I, K) { \ |
| 120 | if (unlikely(i->count < n)) \ |
| 121 | n = i->count; \ |
| 122 | if (likely(n)) { \ |
| 123 | if (likely(iter_is_ubuf(i))) { \ |
| 124 | void __user *base; \ |
| 125 | size_t len; \ |
| 126 | iterate_buf(i, n, base, len, off, \ |
| 127 | i->ubuf, (I)) \ |
| 128 | } else if (likely(iter_is_iovec(i))) { \ |
| 129 | const struct iovec *iov = i->iov; \ |
| 130 | void __user *base; \ |
| 131 | size_t len; \ |
| 132 | iterate_iovec(i, n, base, len, off, \ |
| 133 | iov, (I)) \ |
| 134 | i->nr_segs -= iov - i->iov; \ |
| 135 | i->iov = iov; \ |
| 136 | } else if (iov_iter_is_bvec(i)) { \ |
| 137 | const struct bio_vec *bvec = i->bvec; \ |
| 138 | void *base; \ |
| 139 | size_t len; \ |
| 140 | iterate_bvec(i, n, base, len, off, \ |
| 141 | bvec, (K)) \ |
| 142 | i->nr_segs -= bvec - i->bvec; \ |
| 143 | i->bvec = bvec; \ |
| 144 | } else if (iov_iter_is_kvec(i)) { \ |
| 145 | const struct kvec *kvec = i->kvec; \ |
| 146 | void *base; \ |
| 147 | size_t len; \ |
| 148 | iterate_iovec(i, n, base, len, off, \ |
| 149 | kvec, (K)) \ |
| 150 | i->nr_segs -= kvec - i->kvec; \ |
| 151 | i->kvec = kvec; \ |
| 152 | } else if (iov_iter_is_xarray(i)) { \ |
| 153 | void *base; \ |
| 154 | size_t len; \ |
| 155 | iterate_xarray(i, n, base, len, off, \ |
| 156 | (K)) \ |
| 157 | } \ |
| 158 | i->count -= n; \ |
| 159 | } \ |
| 160 | } |
| 161 | #define iterate_and_advance(i, n, base, len, off, I, K) \ |
| 162 | __iterate_and_advance(i, n, base, len, off, I, ((void)(K),0)) |
| 163 | |
| 164 | static int copyout(void __user *to, const void *from, size_t n) |
| 165 | { |
| 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 | |
| 175 | static int copyin(void *to, const void __user *from, size_t n) |
| 176 | { |
| 177 | if (should_fail_usercopy()) |
| 178 | return n; |
| 179 | if (access_ok(from, n)) { |
| 180 | instrument_copy_from_user(to, from, n); |
| 181 | n = raw_copy_from_user(to, from, n); |
| 182 | } |
| 183 | return n; |
| 184 | } |
| 185 | |
| 186 | static inline struct pipe_buffer *pipe_buf(const struct pipe_inode_info *pipe, |
| 187 | unsigned int slot) |
| 188 | { |
| 189 | return &pipe->bufs[slot & (pipe->ring_size - 1)]; |
| 190 | } |
| 191 | |
| 192 | #ifdef PIPE_PARANOIA |
| 193 | static bool sanity(const struct iov_iter *i) |
| 194 | { |
| 195 | struct pipe_inode_info *pipe = i->pipe; |
| 196 | unsigned int p_head = pipe->head; |
| 197 | unsigned int p_tail = pipe->tail; |
| 198 | unsigned int p_occupancy = pipe_occupancy(p_head, p_tail); |
| 199 | unsigned int i_head = i->head; |
| 200 | unsigned int idx; |
| 201 | |
| 202 | if (i->last_offset) { |
| 203 | struct pipe_buffer *p; |
| 204 | if (unlikely(p_occupancy == 0)) |
| 205 | goto Bad; // pipe must be non-empty |
| 206 | if (unlikely(i_head != p_head - 1)) |
| 207 | goto Bad; // must be at the last buffer... |
| 208 | |
| 209 | p = pipe_buf(pipe, i_head); |
| 210 | if (unlikely(p->offset + p->len != abs(i->last_offset))) |
| 211 | goto Bad; // ... at the end of segment |
| 212 | } else { |
| 213 | if (i_head != p_head) |
| 214 | goto Bad; // must be right after the last buffer |
| 215 | } |
| 216 | return true; |
| 217 | Bad: |
| 218 | printk(KERN_ERR "idx = %d, offset = %d\n", i_head, i->last_offset); |
| 219 | printk(KERN_ERR "head = %d, tail = %d, buffers = %d\n", |
| 220 | p_head, p_tail, pipe->ring_size); |
| 221 | for (idx = 0; idx < pipe->ring_size; idx++) |
| 222 | printk(KERN_ERR "[%p %p %d %d]\n", |
| 223 | pipe->bufs[idx].ops, |
| 224 | pipe->bufs[idx].page, |
| 225 | pipe->bufs[idx].offset, |
| 226 | pipe->bufs[idx].len); |
| 227 | WARN_ON(1); |
| 228 | return false; |
| 229 | } |
| 230 | #else |
| 231 | #define sanity(i) true |
| 232 | #endif |
| 233 | |
| 234 | static struct page *push_anon(struct pipe_inode_info *pipe, unsigned size) |
| 235 | { |
| 236 | struct page *page = alloc_page(GFP_USER); |
| 237 | if (page) { |
| 238 | struct pipe_buffer *buf = pipe_buf(pipe, pipe->head++); |
| 239 | *buf = (struct pipe_buffer) { |
| 240 | .ops = &default_pipe_buf_ops, |
| 241 | .page = page, |
| 242 | .offset = 0, |
| 243 | .len = size |
| 244 | }; |
| 245 | } |
| 246 | return page; |
| 247 | } |
| 248 | |
| 249 | static void push_page(struct pipe_inode_info *pipe, struct page *page, |
| 250 | unsigned int offset, unsigned int size) |
| 251 | { |
| 252 | struct pipe_buffer *buf = pipe_buf(pipe, pipe->head++); |
| 253 | *buf = (struct pipe_buffer) { |
| 254 | .ops = &page_cache_pipe_buf_ops, |
| 255 | .page = page, |
| 256 | .offset = offset, |
| 257 | .len = size |
| 258 | }; |
| 259 | get_page(page); |
| 260 | } |
| 261 | |
| 262 | static inline int last_offset(const struct pipe_buffer *buf) |
| 263 | { |
| 264 | if (buf->ops == &default_pipe_buf_ops) |
| 265 | return buf->len; // buf->offset is 0 for those |
| 266 | else |
| 267 | return -(buf->offset + buf->len); |
| 268 | } |
| 269 | |
| 270 | static struct page *append_pipe(struct iov_iter *i, size_t size, |
| 271 | unsigned int *off) |
| 272 | { |
| 273 | struct pipe_inode_info *pipe = i->pipe; |
| 274 | int offset = i->last_offset; |
| 275 | struct pipe_buffer *buf; |
| 276 | struct page *page; |
| 277 | |
| 278 | if (offset > 0 && offset < PAGE_SIZE) { |
| 279 | // some space in the last buffer; add to it |
| 280 | buf = pipe_buf(pipe, pipe->head - 1); |
| 281 | size = min_t(size_t, size, PAGE_SIZE - offset); |
| 282 | buf->len += size; |
| 283 | i->last_offset += size; |
| 284 | i->count -= size; |
| 285 | *off = offset; |
| 286 | return buf->page; |
| 287 | } |
| 288 | // OK, we need a new buffer |
| 289 | *off = 0; |
| 290 | size = min_t(size_t, size, PAGE_SIZE); |
| 291 | if (pipe_full(pipe->head, pipe->tail, pipe->max_usage)) |
| 292 | return NULL; |
| 293 | page = push_anon(pipe, size); |
| 294 | if (!page) |
| 295 | return NULL; |
| 296 | i->head = pipe->head - 1; |
| 297 | i->last_offset = size; |
| 298 | i->count -= size; |
| 299 | return page; |
| 300 | } |
| 301 | |
| 302 | static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes, |
| 303 | struct iov_iter *i) |
| 304 | { |
| 305 | struct pipe_inode_info *pipe = i->pipe; |
| 306 | unsigned int head = pipe->head; |
| 307 | |
| 308 | if (unlikely(bytes > i->count)) |
| 309 | bytes = i->count; |
| 310 | |
| 311 | if (unlikely(!bytes)) |
| 312 | return 0; |
| 313 | |
| 314 | if (!sanity(i)) |
| 315 | return 0; |
| 316 | |
| 317 | if (offset && i->last_offset == -offset) { // could we merge it? |
| 318 | struct pipe_buffer *buf = pipe_buf(pipe, head - 1); |
| 319 | if (buf->page == page) { |
| 320 | buf->len += bytes; |
| 321 | i->last_offset -= bytes; |
| 322 | i->count -= bytes; |
| 323 | return bytes; |
| 324 | } |
| 325 | } |
| 326 | if (pipe_full(pipe->head, pipe->tail, pipe->max_usage)) |
| 327 | return 0; |
| 328 | |
| 329 | push_page(pipe, page, offset, bytes); |
| 330 | i->last_offset = -(offset + bytes); |
| 331 | i->head = head; |
| 332 | i->count -= bytes; |
| 333 | return bytes; |
| 334 | } |
| 335 | |
| 336 | /* |
| 337 | * fault_in_iov_iter_readable - fault in iov iterator for reading |
| 338 | * @i: iterator |
| 339 | * @size: maximum length |
| 340 | * |
| 341 | * Fault in one or more iovecs of the given iov_iter, to a maximum length of |
| 342 | * @size. For each iovec, fault in each page that constitutes the iovec. |
| 343 | * |
| 344 | * Returns the number of bytes not faulted in (like copy_to_user() and |
| 345 | * copy_from_user()). |
| 346 | * |
| 347 | * Always returns 0 for non-userspace iterators. |
| 348 | */ |
| 349 | size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t size) |
| 350 | { |
| 351 | if (iter_is_ubuf(i)) { |
| 352 | size_t n = min(size, iov_iter_count(i)); |
| 353 | n -= fault_in_readable(i->ubuf + i->iov_offset, n); |
| 354 | return size - n; |
| 355 | } else if (iter_is_iovec(i)) { |
| 356 | size_t count = min(size, iov_iter_count(i)); |
| 357 | const struct iovec *p; |
| 358 | size_t skip; |
| 359 | |
| 360 | size -= count; |
| 361 | for (p = i->iov, skip = i->iov_offset; count; p++, skip = 0) { |
| 362 | size_t len = min(count, p->iov_len - skip); |
| 363 | size_t ret; |
| 364 | |
| 365 | if (unlikely(!len)) |
| 366 | continue; |
| 367 | ret = fault_in_readable(p->iov_base + skip, len); |
| 368 | count -= len - ret; |
| 369 | if (ret) |
| 370 | break; |
| 371 | } |
| 372 | return count + size; |
| 373 | } |
| 374 | return 0; |
| 375 | } |
| 376 | EXPORT_SYMBOL(fault_in_iov_iter_readable); |
| 377 | |
| 378 | /* |
| 379 | * fault_in_iov_iter_writeable - fault in iov iterator for writing |
| 380 | * @i: iterator |
| 381 | * @size: maximum length |
| 382 | * |
| 383 | * Faults in the iterator using get_user_pages(), i.e., without triggering |
| 384 | * hardware page faults. This is primarily useful when we already know that |
| 385 | * some or all of the pages in @i aren't in memory. |
| 386 | * |
| 387 | * Returns the number of bytes not faulted in, like copy_to_user() and |
| 388 | * copy_from_user(). |
| 389 | * |
| 390 | * Always returns 0 for non-user-space iterators. |
| 391 | */ |
| 392 | size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t size) |
| 393 | { |
| 394 | if (iter_is_ubuf(i)) { |
| 395 | size_t n = min(size, iov_iter_count(i)); |
| 396 | n -= fault_in_safe_writeable(i->ubuf + i->iov_offset, n); |
| 397 | return size - n; |
| 398 | } else if (iter_is_iovec(i)) { |
| 399 | size_t count = min(size, iov_iter_count(i)); |
| 400 | const struct iovec *p; |
| 401 | size_t skip; |
| 402 | |
| 403 | size -= count; |
| 404 | for (p = i->iov, skip = i->iov_offset; count; p++, skip = 0) { |
| 405 | size_t len = min(count, p->iov_len - skip); |
| 406 | size_t ret; |
| 407 | |
| 408 | if (unlikely(!len)) |
| 409 | continue; |
| 410 | ret = fault_in_safe_writeable(p->iov_base + skip, len); |
| 411 | count -= len - ret; |
| 412 | if (ret) |
| 413 | break; |
| 414 | } |
| 415 | return count + size; |
| 416 | } |
| 417 | return 0; |
| 418 | } |
| 419 | EXPORT_SYMBOL(fault_in_iov_iter_writeable); |
| 420 | |
| 421 | void iov_iter_init(struct iov_iter *i, unsigned int direction, |
| 422 | const struct iovec *iov, unsigned long nr_segs, |
| 423 | size_t count) |
| 424 | { |
| 425 | WARN_ON(direction & ~(READ | WRITE)); |
| 426 | *i = (struct iov_iter) { |
| 427 | .iter_type = ITER_IOVEC, |
| 428 | .nofault = false, |
| 429 | .user_backed = true, |
| 430 | .data_source = direction, |
| 431 | .iov = iov, |
| 432 | .nr_segs = nr_segs, |
| 433 | .iov_offset = 0, |
| 434 | .count = count |
| 435 | }; |
| 436 | } |
| 437 | EXPORT_SYMBOL(iov_iter_init); |
| 438 | |
| 439 | // returns the offset in partial buffer (if any) |
| 440 | static inline unsigned int pipe_npages(const struct iov_iter *i, int *npages) |
| 441 | { |
| 442 | struct pipe_inode_info *pipe = i->pipe; |
| 443 | int used = pipe->head - pipe->tail; |
| 444 | int off = i->last_offset; |
| 445 | |
| 446 | *npages = max((int)pipe->max_usage - used, 0); |
| 447 | |
| 448 | if (off > 0 && off < PAGE_SIZE) { // anon and not full |
| 449 | (*npages)++; |
| 450 | return off; |
| 451 | } |
| 452 | return 0; |
| 453 | } |
| 454 | |
| 455 | static size_t copy_pipe_to_iter(const void *addr, size_t bytes, |
| 456 | struct iov_iter *i) |
| 457 | { |
| 458 | unsigned int off, chunk; |
| 459 | |
| 460 | if (unlikely(bytes > i->count)) |
| 461 | bytes = i->count; |
| 462 | if (unlikely(!bytes)) |
| 463 | return 0; |
| 464 | |
| 465 | if (!sanity(i)) |
| 466 | return 0; |
| 467 | |
| 468 | for (size_t n = bytes; n; n -= chunk) { |
| 469 | struct page *page = append_pipe(i, n, &off); |
| 470 | chunk = min_t(size_t, n, PAGE_SIZE - off); |
| 471 | if (!page) |
| 472 | return bytes - n; |
| 473 | memcpy_to_page(page, off, addr, chunk); |
| 474 | addr += chunk; |
| 475 | } |
| 476 | return bytes; |
| 477 | } |
| 478 | |
| 479 | static __wsum csum_and_memcpy(void *to, const void *from, size_t len, |
| 480 | __wsum sum, size_t off) |
| 481 | { |
| 482 | __wsum next = csum_partial_copy_nocheck(from, to, len); |
| 483 | return csum_block_add(sum, next, off); |
| 484 | } |
| 485 | |
| 486 | static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes, |
| 487 | struct iov_iter *i, __wsum *sump) |
| 488 | { |
| 489 | __wsum sum = *sump; |
| 490 | size_t off = 0; |
| 491 | unsigned int chunk, r; |
| 492 | |
| 493 | if (unlikely(bytes > i->count)) |
| 494 | bytes = i->count; |
| 495 | if (unlikely(!bytes)) |
| 496 | return 0; |
| 497 | |
| 498 | if (!sanity(i)) |
| 499 | return 0; |
| 500 | |
| 501 | while (bytes) { |
| 502 | struct page *page = append_pipe(i, bytes, &r); |
| 503 | char *p; |
| 504 | |
| 505 | if (!page) |
| 506 | break; |
| 507 | chunk = min_t(size_t, bytes, PAGE_SIZE - r); |
| 508 | p = kmap_local_page(page); |
| 509 | sum = csum_and_memcpy(p + r, addr + off, chunk, sum, off); |
| 510 | kunmap_local(p); |
| 511 | off += chunk; |
| 512 | bytes -= chunk; |
| 513 | } |
| 514 | *sump = sum; |
| 515 | return off; |
| 516 | } |
| 517 | |
| 518 | size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i) |
| 519 | { |
| 520 | if (unlikely(iov_iter_is_pipe(i))) |
| 521 | return copy_pipe_to_iter(addr, bytes, i); |
| 522 | if (user_backed_iter(i)) |
| 523 | might_fault(); |
| 524 | iterate_and_advance(i, bytes, base, len, off, |
| 525 | copyout(base, addr + off, len), |
| 526 | memcpy(base, addr + off, len) |
| 527 | ) |
| 528 | |
| 529 | return bytes; |
| 530 | } |
| 531 | EXPORT_SYMBOL(_copy_to_iter); |
| 532 | |
| 533 | #ifdef CONFIG_ARCH_HAS_COPY_MC |
| 534 | static int copyout_mc(void __user *to, const void *from, size_t n) |
| 535 | { |
| 536 | if (access_ok(to, n)) { |
| 537 | instrument_copy_to_user(to, from, n); |
| 538 | n = copy_mc_to_user((__force void *) to, from, n); |
| 539 | } |
| 540 | return n; |
| 541 | } |
| 542 | |
| 543 | static size_t copy_mc_pipe_to_iter(const void *addr, size_t bytes, |
| 544 | struct iov_iter *i) |
| 545 | { |
| 546 | size_t xfer = 0; |
| 547 | unsigned int off, chunk; |
| 548 | |
| 549 | if (unlikely(bytes > i->count)) |
| 550 | bytes = i->count; |
| 551 | if (unlikely(!bytes)) |
| 552 | return 0; |
| 553 | |
| 554 | if (!sanity(i)) |
| 555 | return 0; |
| 556 | |
| 557 | while (bytes) { |
| 558 | struct page *page = append_pipe(i, bytes, &off); |
| 559 | unsigned long rem; |
| 560 | char *p; |
| 561 | |
| 562 | if (!page) |
| 563 | break; |
| 564 | chunk = min_t(size_t, bytes, PAGE_SIZE - off); |
| 565 | p = kmap_local_page(page); |
| 566 | rem = copy_mc_to_kernel(p + off, addr + xfer, chunk); |
| 567 | chunk -= rem; |
| 568 | kunmap_local(p); |
| 569 | xfer += chunk; |
| 570 | bytes -= chunk; |
| 571 | if (rem) { |
| 572 | iov_iter_revert(i, rem); |
| 573 | break; |
| 574 | } |
| 575 | } |
| 576 | return xfer; |
| 577 | } |
| 578 | |
| 579 | /** |
| 580 | * _copy_mc_to_iter - copy to iter with source memory error exception handling |
| 581 | * @addr: source kernel address |
| 582 | * @bytes: total transfer length |
| 583 | * @i: destination iterator |
| 584 | * |
| 585 | * The pmem driver deploys this for the dax operation |
| 586 | * (dax_copy_to_iter()) for dax reads (bypass page-cache and the |
| 587 | * block-layer). Upon #MC read(2) aborts and returns EIO or the bytes |
| 588 | * successfully copied. |
| 589 | * |
| 590 | * The main differences between this and typical _copy_to_iter(). |
| 591 | * |
| 592 | * * Typical tail/residue handling after a fault retries the copy |
| 593 | * byte-by-byte until the fault happens again. Re-triggering machine |
| 594 | * checks is potentially fatal so the implementation uses source |
| 595 | * alignment and poison alignment assumptions to avoid re-triggering |
| 596 | * hardware exceptions. |
| 597 | * |
| 598 | * * ITER_KVEC, ITER_PIPE, and ITER_BVEC can return short copies. |
| 599 | * Compare to copy_to_iter() where only ITER_IOVEC attempts might return |
| 600 | * a short copy. |
| 601 | * |
| 602 | * Return: number of bytes copied (may be %0) |
| 603 | */ |
| 604 | size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i) |
| 605 | { |
| 606 | if (unlikely(iov_iter_is_pipe(i))) |
| 607 | return copy_mc_pipe_to_iter(addr, bytes, i); |
| 608 | if (user_backed_iter(i)) |
| 609 | might_fault(); |
| 610 | __iterate_and_advance(i, bytes, base, len, off, |
| 611 | copyout_mc(base, addr + off, len), |
| 612 | copy_mc_to_kernel(base, addr + off, len) |
| 613 | ) |
| 614 | |
| 615 | return bytes; |
| 616 | } |
| 617 | EXPORT_SYMBOL_GPL(_copy_mc_to_iter); |
| 618 | #endif /* CONFIG_ARCH_HAS_COPY_MC */ |
| 619 | |
| 620 | size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) |
| 621 | { |
| 622 | if (unlikely(iov_iter_is_pipe(i))) { |
| 623 | WARN_ON(1); |
| 624 | return 0; |
| 625 | } |
| 626 | if (user_backed_iter(i)) |
| 627 | might_fault(); |
| 628 | iterate_and_advance(i, bytes, base, len, off, |
| 629 | copyin(addr + off, base, len), |
| 630 | memcpy(addr + off, base, len) |
| 631 | ) |
| 632 | |
| 633 | return bytes; |
| 634 | } |
| 635 | EXPORT_SYMBOL(_copy_from_iter); |
| 636 | |
| 637 | size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i) |
| 638 | { |
| 639 | if (unlikely(iov_iter_is_pipe(i))) { |
| 640 | WARN_ON(1); |
| 641 | return 0; |
| 642 | } |
| 643 | iterate_and_advance(i, bytes, base, len, off, |
| 644 | __copy_from_user_inatomic_nocache(addr + off, base, len), |
| 645 | memcpy(addr + off, base, len) |
| 646 | ) |
| 647 | |
| 648 | return bytes; |
| 649 | } |
| 650 | EXPORT_SYMBOL(_copy_from_iter_nocache); |
| 651 | |
| 652 | #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE |
| 653 | /** |
| 654 | * _copy_from_iter_flushcache - write destination through cpu cache |
| 655 | * @addr: destination kernel address |
| 656 | * @bytes: total transfer length |
| 657 | * @i: source iterator |
| 658 | * |
| 659 | * The pmem driver arranges for filesystem-dax to use this facility via |
| 660 | * dax_copy_from_iter() for ensuring that writes to persistent memory |
| 661 | * are flushed through the CPU cache. It is differentiated from |
| 662 | * _copy_from_iter_nocache() in that guarantees all data is flushed for |
| 663 | * all iterator types. The _copy_from_iter_nocache() only attempts to |
| 664 | * bypass the cache for the ITER_IOVEC case, and on some archs may use |
| 665 | * instructions that strand dirty-data in the cache. |
| 666 | * |
| 667 | * Return: number of bytes copied (may be %0) |
| 668 | */ |
| 669 | size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i) |
| 670 | { |
| 671 | if (unlikely(iov_iter_is_pipe(i))) { |
| 672 | WARN_ON(1); |
| 673 | return 0; |
| 674 | } |
| 675 | iterate_and_advance(i, bytes, base, len, off, |
| 676 | __copy_from_user_flushcache(addr + off, base, len), |
| 677 | memcpy_flushcache(addr + off, base, len) |
| 678 | ) |
| 679 | |
| 680 | return bytes; |
| 681 | } |
| 682 | EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache); |
| 683 | #endif |
| 684 | |
| 685 | static inline bool page_copy_sane(struct page *page, size_t offset, size_t n) |
| 686 | { |
| 687 | struct page *head; |
| 688 | size_t v = n + offset; |
| 689 | |
| 690 | /* |
| 691 | * The general case needs to access the page order in order |
| 692 | * to compute the page size. |
| 693 | * However, we mostly deal with order-0 pages and thus can |
| 694 | * avoid a possible cache line miss for requests that fit all |
| 695 | * page orders. |
| 696 | */ |
| 697 | if (n <= v && v <= PAGE_SIZE) |
| 698 | return true; |
| 699 | |
| 700 | head = compound_head(page); |
| 701 | v += (page - head) << PAGE_SHIFT; |
| 702 | |
| 703 | if (likely(n <= v && v <= (page_size(head)))) |
| 704 | return true; |
| 705 | WARN_ON(1); |
| 706 | return false; |
| 707 | } |
| 708 | |
| 709 | size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, |
| 710 | struct iov_iter *i) |
| 711 | { |
| 712 | size_t res = 0; |
| 713 | if (unlikely(!page_copy_sane(page, offset, bytes))) |
| 714 | return 0; |
| 715 | if (unlikely(iov_iter_is_pipe(i))) |
| 716 | return copy_page_to_iter_pipe(page, offset, bytes, i); |
| 717 | page += offset / PAGE_SIZE; // first subpage |
| 718 | offset %= PAGE_SIZE; |
| 719 | while (1) { |
| 720 | void *kaddr = kmap_local_page(page); |
| 721 | size_t n = min(bytes, (size_t)PAGE_SIZE - offset); |
| 722 | n = _copy_to_iter(kaddr + offset, n, i); |
| 723 | kunmap_local(kaddr); |
| 724 | res += n; |
| 725 | bytes -= n; |
| 726 | if (!bytes || !n) |
| 727 | break; |
| 728 | offset += n; |
| 729 | if (offset == PAGE_SIZE) { |
| 730 | page++; |
| 731 | offset = 0; |
| 732 | } |
| 733 | } |
| 734 | return res; |
| 735 | } |
| 736 | EXPORT_SYMBOL(copy_page_to_iter); |
| 737 | |
| 738 | size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, |
| 739 | struct iov_iter *i) |
| 740 | { |
| 741 | size_t res = 0; |
| 742 | if (!page_copy_sane(page, offset, bytes)) |
| 743 | return 0; |
| 744 | page += offset / PAGE_SIZE; // first subpage |
| 745 | offset %= PAGE_SIZE; |
| 746 | while (1) { |
| 747 | void *kaddr = kmap_local_page(page); |
| 748 | size_t n = min(bytes, (size_t)PAGE_SIZE - offset); |
| 749 | n = _copy_from_iter(kaddr + offset, n, i); |
| 750 | kunmap_local(kaddr); |
| 751 | res += n; |
| 752 | bytes -= n; |
| 753 | if (!bytes || !n) |
| 754 | break; |
| 755 | offset += n; |
| 756 | if (offset == PAGE_SIZE) { |
| 757 | page++; |
| 758 | offset = 0; |
| 759 | } |
| 760 | } |
| 761 | return res; |
| 762 | } |
| 763 | EXPORT_SYMBOL(copy_page_from_iter); |
| 764 | |
| 765 | static size_t pipe_zero(size_t bytes, struct iov_iter *i) |
| 766 | { |
| 767 | unsigned int chunk, off; |
| 768 | |
| 769 | if (unlikely(bytes > i->count)) |
| 770 | bytes = i->count; |
| 771 | if (unlikely(!bytes)) |
| 772 | return 0; |
| 773 | |
| 774 | if (!sanity(i)) |
| 775 | return 0; |
| 776 | |
| 777 | for (size_t n = bytes; n; n -= chunk) { |
| 778 | struct page *page = append_pipe(i, n, &off); |
| 779 | char *p; |
| 780 | |
| 781 | if (!page) |
| 782 | return bytes - n; |
| 783 | chunk = min_t(size_t, n, PAGE_SIZE - off); |
| 784 | p = kmap_local_page(page); |
| 785 | memset(p + off, 0, chunk); |
| 786 | kunmap_local(p); |
| 787 | } |
| 788 | return bytes; |
| 789 | } |
| 790 | |
| 791 | size_t iov_iter_zero(size_t bytes, struct iov_iter *i) |
| 792 | { |
| 793 | if (unlikely(iov_iter_is_pipe(i))) |
| 794 | return pipe_zero(bytes, i); |
| 795 | iterate_and_advance(i, bytes, base, len, count, |
| 796 | clear_user(base, len), |
| 797 | memset(base, 0, len) |
| 798 | ) |
| 799 | |
| 800 | return bytes; |
| 801 | } |
| 802 | EXPORT_SYMBOL(iov_iter_zero); |
| 803 | |
| 804 | size_t copy_page_from_iter_atomic(struct page *page, unsigned offset, size_t bytes, |
| 805 | struct iov_iter *i) |
| 806 | { |
| 807 | char *kaddr = kmap_atomic(page), *p = kaddr + offset; |
| 808 | if (unlikely(!page_copy_sane(page, offset, bytes))) { |
| 809 | kunmap_atomic(kaddr); |
| 810 | return 0; |
| 811 | } |
| 812 | if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { |
| 813 | kunmap_atomic(kaddr); |
| 814 | WARN_ON(1); |
| 815 | return 0; |
| 816 | } |
| 817 | iterate_and_advance(i, bytes, base, len, off, |
| 818 | copyin(p + off, base, len), |
| 819 | memcpy(p + off, base, len) |
| 820 | ) |
| 821 | kunmap_atomic(kaddr); |
| 822 | return bytes; |
| 823 | } |
| 824 | EXPORT_SYMBOL(copy_page_from_iter_atomic); |
| 825 | |
| 826 | static void pipe_advance(struct iov_iter *i, size_t size) |
| 827 | { |
| 828 | struct pipe_inode_info *pipe = i->pipe; |
| 829 | int off = i->last_offset; |
| 830 | |
| 831 | if (!off && !size) { |
| 832 | pipe_discard_from(pipe, i->start_head); // discard everything |
| 833 | return; |
| 834 | } |
| 835 | i->count -= size; |
| 836 | while (1) { |
| 837 | struct pipe_buffer *buf = pipe_buf(pipe, i->head); |
| 838 | if (off) /* make it relative to the beginning of buffer */ |
| 839 | size += abs(off) - buf->offset; |
| 840 | if (size <= buf->len) { |
| 841 | buf->len = size; |
| 842 | i->last_offset = last_offset(buf); |
| 843 | break; |
| 844 | } |
| 845 | size -= buf->len; |
| 846 | i->head++; |
| 847 | off = 0; |
| 848 | } |
| 849 | pipe_discard_from(pipe, i->head + 1); // discard everything past this one |
| 850 | } |
| 851 | |
| 852 | static void iov_iter_bvec_advance(struct iov_iter *i, size_t size) |
| 853 | { |
| 854 | const struct bio_vec *bvec, *end; |
| 855 | |
| 856 | if (!i->count) |
| 857 | return; |
| 858 | i->count -= size; |
| 859 | |
| 860 | size += i->iov_offset; |
| 861 | |
| 862 | for (bvec = i->bvec, end = bvec + i->nr_segs; bvec < end; bvec++) { |
| 863 | if (likely(size < bvec->bv_len)) |
| 864 | break; |
| 865 | size -= bvec->bv_len; |
| 866 | } |
| 867 | i->iov_offset = size; |
| 868 | i->nr_segs -= bvec - i->bvec; |
| 869 | i->bvec = bvec; |
| 870 | } |
| 871 | |
| 872 | static void iov_iter_iovec_advance(struct iov_iter *i, size_t size) |
| 873 | { |
| 874 | const struct iovec *iov, *end; |
| 875 | |
| 876 | if (!i->count) |
| 877 | return; |
| 878 | i->count -= size; |
| 879 | |
| 880 | size += i->iov_offset; // from beginning of current segment |
| 881 | for (iov = i->iov, end = iov + i->nr_segs; iov < end; iov++) { |
| 882 | if (likely(size < iov->iov_len)) |
| 883 | break; |
| 884 | size -= iov->iov_len; |
| 885 | } |
| 886 | i->iov_offset = size; |
| 887 | i->nr_segs -= iov - i->iov; |
| 888 | i->iov = iov; |
| 889 | } |
| 890 | |
| 891 | void iov_iter_advance(struct iov_iter *i, size_t size) |
| 892 | { |
| 893 | if (unlikely(i->count < size)) |
| 894 | size = i->count; |
| 895 | if (likely(iter_is_ubuf(i)) || unlikely(iov_iter_is_xarray(i))) { |
| 896 | i->iov_offset += size; |
| 897 | i->count -= size; |
| 898 | } else if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) { |
| 899 | /* iovec and kvec have identical layouts */ |
| 900 | iov_iter_iovec_advance(i, size); |
| 901 | } else if (iov_iter_is_bvec(i)) { |
| 902 | iov_iter_bvec_advance(i, size); |
| 903 | } else if (iov_iter_is_pipe(i)) { |
| 904 | pipe_advance(i, size); |
| 905 | } else if (iov_iter_is_discard(i)) { |
| 906 | i->count -= size; |
| 907 | } |
| 908 | } |
| 909 | EXPORT_SYMBOL(iov_iter_advance); |
| 910 | |
| 911 | void iov_iter_revert(struct iov_iter *i, size_t unroll) |
| 912 | { |
| 913 | if (!unroll) |
| 914 | return; |
| 915 | if (WARN_ON(unroll > MAX_RW_COUNT)) |
| 916 | return; |
| 917 | i->count += unroll; |
| 918 | if (unlikely(iov_iter_is_pipe(i))) { |
| 919 | struct pipe_inode_info *pipe = i->pipe; |
| 920 | unsigned int head = pipe->head; |
| 921 | |
| 922 | while (head > i->start_head) { |
| 923 | struct pipe_buffer *b = pipe_buf(pipe, --head); |
| 924 | if (unroll < b->len) { |
| 925 | b->len -= unroll; |
| 926 | i->last_offset = last_offset(b); |
| 927 | i->head = head; |
| 928 | return; |
| 929 | } |
| 930 | unroll -= b->len; |
| 931 | pipe_buf_release(pipe, b); |
| 932 | pipe->head--; |
| 933 | } |
| 934 | i->last_offset = 0; |
| 935 | i->head = head; |
| 936 | return; |
| 937 | } |
| 938 | if (unlikely(iov_iter_is_discard(i))) |
| 939 | return; |
| 940 | if (unroll <= i->iov_offset) { |
| 941 | i->iov_offset -= unroll; |
| 942 | return; |
| 943 | } |
| 944 | unroll -= i->iov_offset; |
| 945 | if (iov_iter_is_xarray(i) || iter_is_ubuf(i)) { |
| 946 | BUG(); /* We should never go beyond the start of the specified |
| 947 | * range since we might then be straying into pages that |
| 948 | * aren't pinned. |
| 949 | */ |
| 950 | } else if (iov_iter_is_bvec(i)) { |
| 951 | const struct bio_vec *bvec = i->bvec; |
| 952 | while (1) { |
| 953 | size_t n = (--bvec)->bv_len; |
| 954 | i->nr_segs++; |
| 955 | if (unroll <= n) { |
| 956 | i->bvec = bvec; |
| 957 | i->iov_offset = n - unroll; |
| 958 | return; |
| 959 | } |
| 960 | unroll -= n; |
| 961 | } |
| 962 | } else { /* same logics for iovec and kvec */ |
| 963 | const struct iovec *iov = i->iov; |
| 964 | while (1) { |
| 965 | size_t n = (--iov)->iov_len; |
| 966 | i->nr_segs++; |
| 967 | if (unroll <= n) { |
| 968 | i->iov = iov; |
| 969 | i->iov_offset = n - unroll; |
| 970 | return; |
| 971 | } |
| 972 | unroll -= n; |
| 973 | } |
| 974 | } |
| 975 | } |
| 976 | EXPORT_SYMBOL(iov_iter_revert); |
| 977 | |
| 978 | /* |
| 979 | * Return the count of just the current iov_iter segment. |
| 980 | */ |
| 981 | size_t iov_iter_single_seg_count(const struct iov_iter *i) |
| 982 | { |
| 983 | if (i->nr_segs > 1) { |
| 984 | if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) |
| 985 | return min(i->count, i->iov->iov_len - i->iov_offset); |
| 986 | if (iov_iter_is_bvec(i)) |
| 987 | return min(i->count, i->bvec->bv_len - i->iov_offset); |
| 988 | } |
| 989 | return i->count; |
| 990 | } |
| 991 | EXPORT_SYMBOL(iov_iter_single_seg_count); |
| 992 | |
| 993 | void iov_iter_kvec(struct iov_iter *i, unsigned int direction, |
| 994 | const struct kvec *kvec, unsigned long nr_segs, |
| 995 | size_t count) |
| 996 | { |
| 997 | WARN_ON(direction & ~(READ | WRITE)); |
| 998 | *i = (struct iov_iter){ |
| 999 | .iter_type = ITER_KVEC, |
| 1000 | .data_source = direction, |
| 1001 | .kvec = kvec, |
| 1002 | .nr_segs = nr_segs, |
| 1003 | .iov_offset = 0, |
| 1004 | .count = count |
| 1005 | }; |
| 1006 | } |
| 1007 | EXPORT_SYMBOL(iov_iter_kvec); |
| 1008 | |
| 1009 | void iov_iter_bvec(struct iov_iter *i, unsigned int direction, |
| 1010 | const struct bio_vec *bvec, unsigned long nr_segs, |
| 1011 | size_t count) |
| 1012 | { |
| 1013 | WARN_ON(direction & ~(READ | WRITE)); |
| 1014 | *i = (struct iov_iter){ |
| 1015 | .iter_type = ITER_BVEC, |
| 1016 | .data_source = direction, |
| 1017 | .bvec = bvec, |
| 1018 | .nr_segs = nr_segs, |
| 1019 | .iov_offset = 0, |
| 1020 | .count = count |
| 1021 | }; |
| 1022 | } |
| 1023 | EXPORT_SYMBOL(iov_iter_bvec); |
| 1024 | |
| 1025 | void iov_iter_pipe(struct iov_iter *i, unsigned int direction, |
| 1026 | struct pipe_inode_info *pipe, |
| 1027 | size_t count) |
| 1028 | { |
| 1029 | BUG_ON(direction != READ); |
| 1030 | WARN_ON(pipe_full(pipe->head, pipe->tail, pipe->ring_size)); |
| 1031 | *i = (struct iov_iter){ |
| 1032 | .iter_type = ITER_PIPE, |
| 1033 | .data_source = false, |
| 1034 | .pipe = pipe, |
| 1035 | .head = pipe->head, |
| 1036 | .start_head = pipe->head, |
| 1037 | .last_offset = 0, |
| 1038 | .count = count |
| 1039 | }; |
| 1040 | } |
| 1041 | EXPORT_SYMBOL(iov_iter_pipe); |
| 1042 | |
| 1043 | /** |
| 1044 | * iov_iter_xarray - Initialise an I/O iterator to use the pages in an xarray |
| 1045 | * @i: The iterator to initialise. |
| 1046 | * @direction: The direction of the transfer. |
| 1047 | * @xarray: The xarray to access. |
| 1048 | * @start: The start file position. |
| 1049 | * @count: The size of the I/O buffer in bytes. |
| 1050 | * |
| 1051 | * Set up an I/O iterator to either draw data out of the pages attached to an |
| 1052 | * inode or to inject data into those pages. The pages *must* be prevented |
| 1053 | * from evaporation, either by taking a ref on them or locking them by the |
| 1054 | * caller. |
| 1055 | */ |
| 1056 | void iov_iter_xarray(struct iov_iter *i, unsigned int direction, |
| 1057 | struct xarray *xarray, loff_t start, size_t count) |
| 1058 | { |
| 1059 | BUG_ON(direction & ~1); |
| 1060 | *i = (struct iov_iter) { |
| 1061 | .iter_type = ITER_XARRAY, |
| 1062 | .data_source = direction, |
| 1063 | .xarray = xarray, |
| 1064 | .xarray_start = start, |
| 1065 | .count = count, |
| 1066 | .iov_offset = 0 |
| 1067 | }; |
| 1068 | } |
| 1069 | EXPORT_SYMBOL(iov_iter_xarray); |
| 1070 | |
| 1071 | /** |
| 1072 | * iov_iter_discard - Initialise an I/O iterator that discards data |
| 1073 | * @i: The iterator to initialise. |
| 1074 | * @direction: The direction of the transfer. |
| 1075 | * @count: The size of the I/O buffer in bytes. |
| 1076 | * |
| 1077 | * Set up an I/O iterator that just discards everything that's written to it. |
| 1078 | * It's only available as a READ iterator. |
| 1079 | */ |
| 1080 | void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count) |
| 1081 | { |
| 1082 | BUG_ON(direction != READ); |
| 1083 | *i = (struct iov_iter){ |
| 1084 | .iter_type = ITER_DISCARD, |
| 1085 | .data_source = false, |
| 1086 | .count = count, |
| 1087 | .iov_offset = 0 |
| 1088 | }; |
| 1089 | } |
| 1090 | EXPORT_SYMBOL(iov_iter_discard); |
| 1091 | |
| 1092 | static bool iov_iter_aligned_iovec(const struct iov_iter *i, unsigned addr_mask, |
| 1093 | unsigned len_mask) |
| 1094 | { |
| 1095 | size_t size = i->count; |
| 1096 | size_t skip = i->iov_offset; |
| 1097 | unsigned k; |
| 1098 | |
| 1099 | for (k = 0; k < i->nr_segs; k++, skip = 0) { |
| 1100 | size_t len = i->iov[k].iov_len - skip; |
| 1101 | |
| 1102 | if (len > size) |
| 1103 | len = size; |
| 1104 | if (len & len_mask) |
| 1105 | return false; |
| 1106 | if ((unsigned long)(i->iov[k].iov_base + skip) & addr_mask) |
| 1107 | return false; |
| 1108 | |
| 1109 | size -= len; |
| 1110 | if (!size) |
| 1111 | break; |
| 1112 | } |
| 1113 | return true; |
| 1114 | } |
| 1115 | |
| 1116 | static bool iov_iter_aligned_bvec(const struct iov_iter *i, unsigned addr_mask, |
| 1117 | unsigned len_mask) |
| 1118 | { |
| 1119 | size_t size = i->count; |
| 1120 | unsigned skip = i->iov_offset; |
| 1121 | unsigned k; |
| 1122 | |
| 1123 | for (k = 0; k < i->nr_segs; k++, skip = 0) { |
| 1124 | size_t len = i->bvec[k].bv_len - skip; |
| 1125 | |
| 1126 | if (len > size) |
| 1127 | len = size; |
| 1128 | if (len & len_mask) |
| 1129 | return false; |
| 1130 | if ((unsigned long)(i->bvec[k].bv_offset + skip) & addr_mask) |
| 1131 | return false; |
| 1132 | |
| 1133 | size -= len; |
| 1134 | if (!size) |
| 1135 | break; |
| 1136 | } |
| 1137 | return true; |
| 1138 | } |
| 1139 | |
| 1140 | /** |
| 1141 | * iov_iter_is_aligned() - Check if the addresses and lengths of each segments |
| 1142 | * are aligned to the parameters. |
| 1143 | * |
| 1144 | * @i: &struct iov_iter to restore |
| 1145 | * @addr_mask: bit mask to check against the iov element's addresses |
| 1146 | * @len_mask: bit mask to check against the iov element's lengths |
| 1147 | * |
| 1148 | * Return: false if any addresses or lengths intersect with the provided masks |
| 1149 | */ |
| 1150 | bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask, |
| 1151 | unsigned len_mask) |
| 1152 | { |
| 1153 | if (likely(iter_is_ubuf(i))) { |
| 1154 | if (i->count & len_mask) |
| 1155 | return false; |
| 1156 | if ((unsigned long)(i->ubuf + i->iov_offset) & addr_mask) |
| 1157 | return false; |
| 1158 | return true; |
| 1159 | } |
| 1160 | |
| 1161 | if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) |
| 1162 | return iov_iter_aligned_iovec(i, addr_mask, len_mask); |
| 1163 | |
| 1164 | if (iov_iter_is_bvec(i)) |
| 1165 | return iov_iter_aligned_bvec(i, addr_mask, len_mask); |
| 1166 | |
| 1167 | if (iov_iter_is_pipe(i)) { |
| 1168 | size_t size = i->count; |
| 1169 | |
| 1170 | if (size & len_mask) |
| 1171 | return false; |
| 1172 | if (size && i->last_offset > 0) { |
| 1173 | if (i->last_offset & addr_mask) |
| 1174 | return false; |
| 1175 | } |
| 1176 | |
| 1177 | return true; |
| 1178 | } |
| 1179 | |
| 1180 | if (iov_iter_is_xarray(i)) { |
| 1181 | if (i->count & len_mask) |
| 1182 | return false; |
| 1183 | if ((i->xarray_start + i->iov_offset) & addr_mask) |
| 1184 | return false; |
| 1185 | } |
| 1186 | |
| 1187 | return true; |
| 1188 | } |
| 1189 | EXPORT_SYMBOL_GPL(iov_iter_is_aligned); |
| 1190 | |
| 1191 | static unsigned long iov_iter_alignment_iovec(const struct iov_iter *i) |
| 1192 | { |
| 1193 | unsigned long res = 0; |
| 1194 | size_t size = i->count; |
| 1195 | size_t skip = i->iov_offset; |
| 1196 | unsigned k; |
| 1197 | |
| 1198 | for (k = 0; k < i->nr_segs; k++, skip = 0) { |
| 1199 | size_t len = i->iov[k].iov_len - skip; |
| 1200 | if (len) { |
| 1201 | res |= (unsigned long)i->iov[k].iov_base + skip; |
| 1202 | if (len > size) |
| 1203 | len = size; |
| 1204 | res |= len; |
| 1205 | size -= len; |
| 1206 | if (!size) |
| 1207 | break; |
| 1208 | } |
| 1209 | } |
| 1210 | return res; |
| 1211 | } |
| 1212 | |
| 1213 | static unsigned long iov_iter_alignment_bvec(const struct iov_iter *i) |
| 1214 | { |
| 1215 | unsigned res = 0; |
| 1216 | size_t size = i->count; |
| 1217 | unsigned skip = i->iov_offset; |
| 1218 | unsigned k; |
| 1219 | |
| 1220 | for (k = 0; k < i->nr_segs; k++, skip = 0) { |
| 1221 | size_t len = i->bvec[k].bv_len - skip; |
| 1222 | res |= (unsigned long)i->bvec[k].bv_offset + skip; |
| 1223 | if (len > size) |
| 1224 | len = size; |
| 1225 | res |= len; |
| 1226 | size -= len; |
| 1227 | if (!size) |
| 1228 | break; |
| 1229 | } |
| 1230 | return res; |
| 1231 | } |
| 1232 | |
| 1233 | unsigned long iov_iter_alignment(const struct iov_iter *i) |
| 1234 | { |
| 1235 | if (likely(iter_is_ubuf(i))) { |
| 1236 | size_t size = i->count; |
| 1237 | if (size) |
| 1238 | return ((unsigned long)i->ubuf + i->iov_offset) | size; |
| 1239 | return 0; |
| 1240 | } |
| 1241 | |
| 1242 | /* iovec and kvec have identical layouts */ |
| 1243 | if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) |
| 1244 | return iov_iter_alignment_iovec(i); |
| 1245 | |
| 1246 | if (iov_iter_is_bvec(i)) |
| 1247 | return iov_iter_alignment_bvec(i); |
| 1248 | |
| 1249 | if (iov_iter_is_pipe(i)) { |
| 1250 | size_t size = i->count; |
| 1251 | |
| 1252 | if (size && i->last_offset > 0) |
| 1253 | return size | i->last_offset; |
| 1254 | return size; |
| 1255 | } |
| 1256 | |
| 1257 | if (iov_iter_is_xarray(i)) |
| 1258 | return (i->xarray_start + i->iov_offset) | i->count; |
| 1259 | |
| 1260 | return 0; |
| 1261 | } |
| 1262 | EXPORT_SYMBOL(iov_iter_alignment); |
| 1263 | |
| 1264 | unsigned long iov_iter_gap_alignment(const struct iov_iter *i) |
| 1265 | { |
| 1266 | unsigned long res = 0; |
| 1267 | unsigned long v = 0; |
| 1268 | size_t size = i->count; |
| 1269 | unsigned k; |
| 1270 | |
| 1271 | if (iter_is_ubuf(i)) |
| 1272 | return 0; |
| 1273 | |
| 1274 | if (WARN_ON(!iter_is_iovec(i))) |
| 1275 | return ~0U; |
| 1276 | |
| 1277 | for (k = 0; k < i->nr_segs; k++) { |
| 1278 | if (i->iov[k].iov_len) { |
| 1279 | unsigned long base = (unsigned long)i->iov[k].iov_base; |
| 1280 | if (v) // if not the first one |
| 1281 | res |= base | v; // this start | previous end |
| 1282 | v = base + i->iov[k].iov_len; |
| 1283 | if (size <= i->iov[k].iov_len) |
| 1284 | break; |
| 1285 | size -= i->iov[k].iov_len; |
| 1286 | } |
| 1287 | } |
| 1288 | return res; |
| 1289 | } |
| 1290 | EXPORT_SYMBOL(iov_iter_gap_alignment); |
| 1291 | |
| 1292 | static int want_pages_array(struct page ***res, size_t size, |
| 1293 | size_t start, unsigned int maxpages) |
| 1294 | { |
| 1295 | unsigned int count = DIV_ROUND_UP(size + start, PAGE_SIZE); |
| 1296 | |
| 1297 | if (count > maxpages) |
| 1298 | count = maxpages; |
| 1299 | WARN_ON(!count); // caller should've prevented that |
| 1300 | if (!*res) { |
| 1301 | *res = kvmalloc_array(count, sizeof(struct page *), GFP_KERNEL); |
| 1302 | if (!*res) |
| 1303 | return 0; |
| 1304 | } |
| 1305 | return count; |
| 1306 | } |
| 1307 | |
| 1308 | static ssize_t pipe_get_pages(struct iov_iter *i, |
| 1309 | struct page ***pages, size_t maxsize, unsigned maxpages, |
| 1310 | size_t *start) |
| 1311 | { |
| 1312 | unsigned int npages, count, off, chunk; |
| 1313 | struct page **p; |
| 1314 | size_t left; |
| 1315 | |
| 1316 | if (!sanity(i)) |
| 1317 | return -EFAULT; |
| 1318 | |
| 1319 | *start = off = pipe_npages(i, &npages); |
| 1320 | if (!npages) |
| 1321 | return -EFAULT; |
| 1322 | count = want_pages_array(pages, maxsize, off, min(npages, maxpages)); |
| 1323 | if (!count) |
| 1324 | return -ENOMEM; |
| 1325 | p = *pages; |
| 1326 | for (npages = 0, left = maxsize ; npages < count; npages++, left -= chunk) { |
| 1327 | struct page *page = append_pipe(i, left, &off); |
| 1328 | if (!page) |
| 1329 | break; |
| 1330 | chunk = min_t(size_t, left, PAGE_SIZE - off); |
| 1331 | get_page(*p++ = page); |
| 1332 | } |
| 1333 | if (!npages) |
| 1334 | return -EFAULT; |
| 1335 | return maxsize - left; |
| 1336 | } |
| 1337 | |
| 1338 | static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa, |
| 1339 | pgoff_t index, unsigned int nr_pages) |
| 1340 | { |
| 1341 | XA_STATE(xas, xa, index); |
| 1342 | struct page *page; |
| 1343 | unsigned int ret = 0; |
| 1344 | |
| 1345 | rcu_read_lock(); |
| 1346 | for (page = xas_load(&xas); page; page = xas_next(&xas)) { |
| 1347 | if (xas_retry(&xas, page)) |
| 1348 | continue; |
| 1349 | |
| 1350 | /* Has the page moved or been split? */ |
| 1351 | if (unlikely(page != xas_reload(&xas))) { |
| 1352 | xas_reset(&xas); |
| 1353 | continue; |
| 1354 | } |
| 1355 | |
| 1356 | pages[ret] = find_subpage(page, xas.xa_index); |
| 1357 | get_page(pages[ret]); |
| 1358 | if (++ret == nr_pages) |
| 1359 | break; |
| 1360 | } |
| 1361 | rcu_read_unlock(); |
| 1362 | return ret; |
| 1363 | } |
| 1364 | |
| 1365 | static ssize_t iter_xarray_get_pages(struct iov_iter *i, |
| 1366 | struct page ***pages, size_t maxsize, |
| 1367 | unsigned maxpages, size_t *_start_offset) |
| 1368 | { |
| 1369 | unsigned nr, offset, count; |
| 1370 | pgoff_t index; |
| 1371 | loff_t pos; |
| 1372 | |
| 1373 | pos = i->xarray_start + i->iov_offset; |
| 1374 | index = pos >> PAGE_SHIFT; |
| 1375 | offset = pos & ~PAGE_MASK; |
| 1376 | *_start_offset = offset; |
| 1377 | |
| 1378 | count = want_pages_array(pages, maxsize, offset, maxpages); |
| 1379 | if (!count) |
| 1380 | return -ENOMEM; |
| 1381 | nr = iter_xarray_populate_pages(*pages, i->xarray, index, count); |
| 1382 | if (nr == 0) |
| 1383 | return 0; |
| 1384 | |
| 1385 | maxsize = min_t(size_t, nr * PAGE_SIZE - offset, maxsize); |
| 1386 | i->iov_offset += maxsize; |
| 1387 | i->count -= maxsize; |
| 1388 | return maxsize; |
| 1389 | } |
| 1390 | |
| 1391 | /* must be done on non-empty ITER_UBUF or ITER_IOVEC one */ |
| 1392 | static unsigned long first_iovec_segment(const struct iov_iter *i, size_t *size) |
| 1393 | { |
| 1394 | size_t skip; |
| 1395 | long k; |
| 1396 | |
| 1397 | if (iter_is_ubuf(i)) |
| 1398 | return (unsigned long)i->ubuf + i->iov_offset; |
| 1399 | |
| 1400 | for (k = 0, skip = i->iov_offset; k < i->nr_segs; k++, skip = 0) { |
| 1401 | size_t len = i->iov[k].iov_len - skip; |
| 1402 | |
| 1403 | if (unlikely(!len)) |
| 1404 | continue; |
| 1405 | if (*size > len) |
| 1406 | *size = len; |
| 1407 | return (unsigned long)i->iov[k].iov_base + skip; |
| 1408 | } |
| 1409 | BUG(); // if it had been empty, we wouldn't get called |
| 1410 | } |
| 1411 | |
| 1412 | /* must be done on non-empty ITER_BVEC one */ |
| 1413 | static struct page *first_bvec_segment(const struct iov_iter *i, |
| 1414 | size_t *size, size_t *start) |
| 1415 | { |
| 1416 | struct page *page; |
| 1417 | size_t skip = i->iov_offset, len; |
| 1418 | |
| 1419 | len = i->bvec->bv_len - skip; |
| 1420 | if (*size > len) |
| 1421 | *size = len; |
| 1422 | skip += i->bvec->bv_offset; |
| 1423 | page = i->bvec->bv_page + skip / PAGE_SIZE; |
| 1424 | *start = skip % PAGE_SIZE; |
| 1425 | return page; |
| 1426 | } |
| 1427 | |
| 1428 | static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i, |
| 1429 | struct page ***pages, size_t maxsize, |
| 1430 | unsigned int maxpages, size_t *start) |
| 1431 | { |
| 1432 | unsigned int n; |
| 1433 | |
| 1434 | if (maxsize > i->count) |
| 1435 | maxsize = i->count; |
| 1436 | if (!maxsize) |
| 1437 | return 0; |
| 1438 | if (maxsize > MAX_RW_COUNT) |
| 1439 | maxsize = MAX_RW_COUNT; |
| 1440 | |
| 1441 | if (likely(user_backed_iter(i))) { |
| 1442 | unsigned int gup_flags = 0; |
| 1443 | unsigned long addr; |
| 1444 | int res; |
| 1445 | |
| 1446 | if (iov_iter_rw(i) != WRITE) |
| 1447 | gup_flags |= FOLL_WRITE; |
| 1448 | if (i->nofault) |
| 1449 | gup_flags |= FOLL_NOFAULT; |
| 1450 | |
| 1451 | addr = first_iovec_segment(i, &maxsize); |
| 1452 | *start = addr % PAGE_SIZE; |
| 1453 | addr &= PAGE_MASK; |
| 1454 | n = want_pages_array(pages, maxsize, *start, maxpages); |
| 1455 | if (!n) |
| 1456 | return -ENOMEM; |
| 1457 | res = get_user_pages_fast(addr, n, gup_flags, *pages); |
| 1458 | if (unlikely(res <= 0)) |
| 1459 | return res; |
| 1460 | maxsize = min_t(size_t, maxsize, res * PAGE_SIZE - *start); |
| 1461 | iov_iter_advance(i, maxsize); |
| 1462 | return maxsize; |
| 1463 | } |
| 1464 | if (iov_iter_is_bvec(i)) { |
| 1465 | struct page **p; |
| 1466 | struct page *page; |
| 1467 | |
| 1468 | page = first_bvec_segment(i, &maxsize, start); |
| 1469 | n = want_pages_array(pages, maxsize, *start, maxpages); |
| 1470 | if (!n) |
| 1471 | return -ENOMEM; |
| 1472 | p = *pages; |
| 1473 | for (int k = 0; k < n; k++) |
| 1474 | get_page(p[k] = page + k); |
| 1475 | maxsize = min_t(size_t, maxsize, n * PAGE_SIZE - *start); |
| 1476 | i->count -= maxsize; |
| 1477 | i->iov_offset += maxsize; |
| 1478 | if (i->iov_offset == i->bvec->bv_len) { |
| 1479 | i->iov_offset = 0; |
| 1480 | i->bvec++; |
| 1481 | i->nr_segs--; |
| 1482 | } |
| 1483 | return maxsize; |
| 1484 | } |
| 1485 | if (iov_iter_is_pipe(i)) |
| 1486 | return pipe_get_pages(i, pages, maxsize, maxpages, start); |
| 1487 | if (iov_iter_is_xarray(i)) |
| 1488 | return iter_xarray_get_pages(i, pages, maxsize, maxpages, start); |
| 1489 | return -EFAULT; |
| 1490 | } |
| 1491 | |
| 1492 | ssize_t iov_iter_get_pages2(struct iov_iter *i, |
| 1493 | struct page **pages, size_t maxsize, unsigned maxpages, |
| 1494 | size_t *start) |
| 1495 | { |
| 1496 | if (!maxpages) |
| 1497 | return 0; |
| 1498 | BUG_ON(!pages); |
| 1499 | |
| 1500 | return __iov_iter_get_pages_alloc(i, &pages, maxsize, maxpages, start); |
| 1501 | } |
| 1502 | EXPORT_SYMBOL(iov_iter_get_pages2); |
| 1503 | |
| 1504 | ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, |
| 1505 | struct page ***pages, size_t maxsize, |
| 1506 | size_t *start) |
| 1507 | { |
| 1508 | ssize_t len; |
| 1509 | |
| 1510 | *pages = NULL; |
| 1511 | |
| 1512 | len = __iov_iter_get_pages_alloc(i, pages, maxsize, ~0U, start); |
| 1513 | if (len <= 0) { |
| 1514 | kvfree(*pages); |
| 1515 | *pages = NULL; |
| 1516 | } |
| 1517 | return len; |
| 1518 | } |
| 1519 | EXPORT_SYMBOL(iov_iter_get_pages_alloc2); |
| 1520 | |
| 1521 | size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, |
| 1522 | struct iov_iter *i) |
| 1523 | { |
| 1524 | __wsum sum, next; |
| 1525 | sum = *csum; |
| 1526 | if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { |
| 1527 | WARN_ON(1); |
| 1528 | return 0; |
| 1529 | } |
| 1530 | iterate_and_advance(i, bytes, base, len, off, ({ |
| 1531 | next = csum_and_copy_from_user(base, addr + off, len); |
| 1532 | sum = csum_block_add(sum, next, off); |
| 1533 | next ? 0 : len; |
| 1534 | }), ({ |
| 1535 | sum = csum_and_memcpy(addr + off, base, len, sum, off); |
| 1536 | }) |
| 1537 | ) |
| 1538 | *csum = sum; |
| 1539 | return bytes; |
| 1540 | } |
| 1541 | EXPORT_SYMBOL(csum_and_copy_from_iter); |
| 1542 | |
| 1543 | size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate, |
| 1544 | struct iov_iter *i) |
| 1545 | { |
| 1546 | struct csum_state *csstate = _csstate; |
| 1547 | __wsum sum, next; |
| 1548 | |
| 1549 | if (unlikely(iov_iter_is_discard(i))) { |
| 1550 | WARN_ON(1); /* for now */ |
| 1551 | return 0; |
| 1552 | } |
| 1553 | |
| 1554 | sum = csum_shift(csstate->csum, csstate->off); |
| 1555 | if (unlikely(iov_iter_is_pipe(i))) |
| 1556 | bytes = csum_and_copy_to_pipe_iter(addr, bytes, i, &sum); |
| 1557 | else iterate_and_advance(i, bytes, base, len, off, ({ |
| 1558 | next = csum_and_copy_to_user(addr + off, base, len); |
| 1559 | sum = csum_block_add(sum, next, off); |
| 1560 | next ? 0 : len; |
| 1561 | }), ({ |
| 1562 | sum = csum_and_memcpy(base, addr + off, len, sum, off); |
| 1563 | }) |
| 1564 | ) |
| 1565 | csstate->csum = csum_shift(sum, csstate->off); |
| 1566 | csstate->off += bytes; |
| 1567 | return bytes; |
| 1568 | } |
| 1569 | EXPORT_SYMBOL(csum_and_copy_to_iter); |
| 1570 | |
| 1571 | size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp, |
| 1572 | struct iov_iter *i) |
| 1573 | { |
| 1574 | #ifdef CONFIG_CRYPTO_HASH |
| 1575 | struct ahash_request *hash = hashp; |
| 1576 | struct scatterlist sg; |
| 1577 | size_t copied; |
| 1578 | |
| 1579 | copied = copy_to_iter(addr, bytes, i); |
| 1580 | sg_init_one(&sg, addr, copied); |
| 1581 | ahash_request_set_crypt(hash, &sg, NULL, copied); |
| 1582 | crypto_ahash_update(hash); |
| 1583 | return copied; |
| 1584 | #else |
| 1585 | return 0; |
| 1586 | #endif |
| 1587 | } |
| 1588 | EXPORT_SYMBOL(hash_and_copy_to_iter); |
| 1589 | |
| 1590 | static int iov_npages(const struct iov_iter *i, int maxpages) |
| 1591 | { |
| 1592 | size_t skip = i->iov_offset, size = i->count; |
| 1593 | const struct iovec *p; |
| 1594 | int npages = 0; |
| 1595 | |
| 1596 | for (p = i->iov; size; skip = 0, p++) { |
| 1597 | unsigned offs = offset_in_page(p->iov_base + skip); |
| 1598 | size_t len = min(p->iov_len - skip, size); |
| 1599 | |
| 1600 | if (len) { |
| 1601 | size -= len; |
| 1602 | npages += DIV_ROUND_UP(offs + len, PAGE_SIZE); |
| 1603 | if (unlikely(npages > maxpages)) |
| 1604 | return maxpages; |
| 1605 | } |
| 1606 | } |
| 1607 | return npages; |
| 1608 | } |
| 1609 | |
| 1610 | static int bvec_npages(const struct iov_iter *i, int maxpages) |
| 1611 | { |
| 1612 | size_t skip = i->iov_offset, size = i->count; |
| 1613 | const struct bio_vec *p; |
| 1614 | int npages = 0; |
| 1615 | |
| 1616 | for (p = i->bvec; size; skip = 0, p++) { |
| 1617 | unsigned offs = (p->bv_offset + skip) % PAGE_SIZE; |
| 1618 | size_t len = min(p->bv_len - skip, size); |
| 1619 | |
| 1620 | size -= len; |
| 1621 | npages += DIV_ROUND_UP(offs + len, PAGE_SIZE); |
| 1622 | if (unlikely(npages > maxpages)) |
| 1623 | return maxpages; |
| 1624 | } |
| 1625 | return npages; |
| 1626 | } |
| 1627 | |
| 1628 | int iov_iter_npages(const struct iov_iter *i, int maxpages) |
| 1629 | { |
| 1630 | if (unlikely(!i->count)) |
| 1631 | return 0; |
| 1632 | if (likely(iter_is_ubuf(i))) { |
| 1633 | unsigned offs = offset_in_page(i->ubuf + i->iov_offset); |
| 1634 | int npages = DIV_ROUND_UP(offs + i->count, PAGE_SIZE); |
| 1635 | return min(npages, maxpages); |
| 1636 | } |
| 1637 | /* iovec and kvec have identical layouts */ |
| 1638 | if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) |
| 1639 | return iov_npages(i, maxpages); |
| 1640 | if (iov_iter_is_bvec(i)) |
| 1641 | return bvec_npages(i, maxpages); |
| 1642 | if (iov_iter_is_pipe(i)) { |
| 1643 | int npages; |
| 1644 | |
| 1645 | if (!sanity(i)) |
| 1646 | return 0; |
| 1647 | |
| 1648 | pipe_npages(i, &npages); |
| 1649 | return min(npages, maxpages); |
| 1650 | } |
| 1651 | if (iov_iter_is_xarray(i)) { |
| 1652 | unsigned offset = (i->xarray_start + i->iov_offset) % PAGE_SIZE; |
| 1653 | int npages = DIV_ROUND_UP(offset + i->count, PAGE_SIZE); |
| 1654 | return min(npages, maxpages); |
| 1655 | } |
| 1656 | return 0; |
| 1657 | } |
| 1658 | EXPORT_SYMBOL(iov_iter_npages); |
| 1659 | |
| 1660 | const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags) |
| 1661 | { |
| 1662 | *new = *old; |
| 1663 | if (unlikely(iov_iter_is_pipe(new))) { |
| 1664 | WARN_ON(1); |
| 1665 | return NULL; |
| 1666 | } |
| 1667 | if (iov_iter_is_bvec(new)) |
| 1668 | return new->bvec = kmemdup(new->bvec, |
| 1669 | new->nr_segs * sizeof(struct bio_vec), |
| 1670 | flags); |
| 1671 | else if (iov_iter_is_kvec(new) || iter_is_iovec(new)) |
| 1672 | /* iovec and kvec have identical layout */ |
| 1673 | return new->iov = kmemdup(new->iov, |
| 1674 | new->nr_segs * sizeof(struct iovec), |
| 1675 | flags); |
| 1676 | return NULL; |
| 1677 | } |
| 1678 | EXPORT_SYMBOL(dup_iter); |
| 1679 | |
| 1680 | static int copy_compat_iovec_from_user(struct iovec *iov, |
| 1681 | const struct iovec __user *uvec, unsigned long nr_segs) |
| 1682 | { |
| 1683 | const struct compat_iovec __user *uiov = |
| 1684 | (const struct compat_iovec __user *)uvec; |
| 1685 | int ret = -EFAULT, i; |
| 1686 | |
| 1687 | if (!user_access_begin(uiov, nr_segs * sizeof(*uiov))) |
| 1688 | return -EFAULT; |
| 1689 | |
| 1690 | for (i = 0; i < nr_segs; i++) { |
| 1691 | compat_uptr_t buf; |
| 1692 | compat_ssize_t len; |
| 1693 | |
| 1694 | unsafe_get_user(len, &uiov[i].iov_len, uaccess_end); |
| 1695 | unsafe_get_user(buf, &uiov[i].iov_base, uaccess_end); |
| 1696 | |
| 1697 | /* check for compat_size_t not fitting in compat_ssize_t .. */ |
| 1698 | if (len < 0) { |
| 1699 | ret = -EINVAL; |
| 1700 | goto uaccess_end; |
| 1701 | } |
| 1702 | iov[i].iov_base = compat_ptr(buf); |
| 1703 | iov[i].iov_len = len; |
| 1704 | } |
| 1705 | |
| 1706 | ret = 0; |
| 1707 | uaccess_end: |
| 1708 | user_access_end(); |
| 1709 | return ret; |
| 1710 | } |
| 1711 | |
| 1712 | static int copy_iovec_from_user(struct iovec *iov, |
| 1713 | const struct iovec __user *uvec, unsigned long nr_segs) |
| 1714 | { |
| 1715 | unsigned long seg; |
| 1716 | |
| 1717 | if (copy_from_user(iov, uvec, nr_segs * sizeof(*uvec))) |
| 1718 | return -EFAULT; |
| 1719 | for (seg = 0; seg < nr_segs; seg++) { |
| 1720 | if ((ssize_t)iov[seg].iov_len < 0) |
| 1721 | return -EINVAL; |
| 1722 | } |
| 1723 | |
| 1724 | return 0; |
| 1725 | } |
| 1726 | |
| 1727 | struct iovec *iovec_from_user(const struct iovec __user *uvec, |
| 1728 | unsigned long nr_segs, unsigned long fast_segs, |
| 1729 | struct iovec *fast_iov, bool compat) |
| 1730 | { |
| 1731 | struct iovec *iov = fast_iov; |
| 1732 | int ret; |
| 1733 | |
| 1734 | /* |
| 1735 | * SuS says "The readv() function *may* fail if the iovcnt argument was |
| 1736 | * less than or equal to 0, or greater than {IOV_MAX}. Linux has |
| 1737 | * traditionally returned zero for zero segments, so... |
| 1738 | */ |
| 1739 | if (nr_segs == 0) |
| 1740 | return iov; |
| 1741 | if (nr_segs > UIO_MAXIOV) |
| 1742 | return ERR_PTR(-EINVAL); |
| 1743 | if (nr_segs > fast_segs) { |
| 1744 | iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL); |
| 1745 | if (!iov) |
| 1746 | return ERR_PTR(-ENOMEM); |
| 1747 | } |
| 1748 | |
| 1749 | if (compat) |
| 1750 | ret = copy_compat_iovec_from_user(iov, uvec, nr_segs); |
| 1751 | else |
| 1752 | ret = copy_iovec_from_user(iov, uvec, nr_segs); |
| 1753 | if (ret) { |
| 1754 | if (iov != fast_iov) |
| 1755 | kfree(iov); |
| 1756 | return ERR_PTR(ret); |
| 1757 | } |
| 1758 | |
| 1759 | return iov; |
| 1760 | } |
| 1761 | |
| 1762 | ssize_t __import_iovec(int type, const struct iovec __user *uvec, |
| 1763 | unsigned nr_segs, unsigned fast_segs, struct iovec **iovp, |
| 1764 | struct iov_iter *i, bool compat) |
| 1765 | { |
| 1766 | ssize_t total_len = 0; |
| 1767 | unsigned long seg; |
| 1768 | struct iovec *iov; |
| 1769 | |
| 1770 | iov = iovec_from_user(uvec, nr_segs, fast_segs, *iovp, compat); |
| 1771 | if (IS_ERR(iov)) { |
| 1772 | *iovp = NULL; |
| 1773 | return PTR_ERR(iov); |
| 1774 | } |
| 1775 | |
| 1776 | /* |
| 1777 | * According to the Single Unix Specification we should return EINVAL if |
| 1778 | * an element length is < 0 when cast to ssize_t or if the total length |
| 1779 | * would overflow the ssize_t return value of the system call. |
| 1780 | * |
| 1781 | * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the |
| 1782 | * overflow case. |
| 1783 | */ |
| 1784 | for (seg = 0; seg < nr_segs; seg++) { |
| 1785 | ssize_t len = (ssize_t)iov[seg].iov_len; |
| 1786 | |
| 1787 | if (!access_ok(iov[seg].iov_base, len)) { |
| 1788 | if (iov != *iovp) |
| 1789 | kfree(iov); |
| 1790 | *iovp = NULL; |
| 1791 | return -EFAULT; |
| 1792 | } |
| 1793 | |
| 1794 | if (len > MAX_RW_COUNT - total_len) { |
| 1795 | len = MAX_RW_COUNT - total_len; |
| 1796 | iov[seg].iov_len = len; |
| 1797 | } |
| 1798 | total_len += len; |
| 1799 | } |
| 1800 | |
| 1801 | iov_iter_init(i, type, iov, nr_segs, total_len); |
| 1802 | if (iov == *iovp) |
| 1803 | *iovp = NULL; |
| 1804 | else |
| 1805 | *iovp = iov; |
| 1806 | return total_len; |
| 1807 | } |
| 1808 | |
| 1809 | /** |
| 1810 | * import_iovec() - Copy an array of &struct iovec from userspace |
| 1811 | * into the kernel, check that it is valid, and initialize a new |
| 1812 | * &struct iov_iter iterator to access it. |
| 1813 | * |
| 1814 | * @type: One of %READ or %WRITE. |
| 1815 | * @uvec: Pointer to the userspace array. |
| 1816 | * @nr_segs: Number of elements in userspace array. |
| 1817 | * @fast_segs: Number of elements in @iov. |
| 1818 | * @iovp: (input and output parameter) Pointer to pointer to (usually small |
| 1819 | * on-stack) kernel array. |
| 1820 | * @i: Pointer to iterator that will be initialized on success. |
| 1821 | * |
| 1822 | * If the array pointed to by *@iov is large enough to hold all @nr_segs, |
| 1823 | * then this function places %NULL in *@iov on return. Otherwise, a new |
| 1824 | * array will be allocated and the result placed in *@iov. This means that |
| 1825 | * the caller may call kfree() on *@iov regardless of whether the small |
| 1826 | * on-stack array was used or not (and regardless of whether this function |
| 1827 | * returns an error or not). |
| 1828 | * |
| 1829 | * Return: Negative error code on error, bytes imported on success |
| 1830 | */ |
| 1831 | ssize_t import_iovec(int type, const struct iovec __user *uvec, |
| 1832 | unsigned nr_segs, unsigned fast_segs, |
| 1833 | struct iovec **iovp, struct iov_iter *i) |
| 1834 | { |
| 1835 | return __import_iovec(type, uvec, nr_segs, fast_segs, iovp, i, |
| 1836 | in_compat_syscall()); |
| 1837 | } |
| 1838 | EXPORT_SYMBOL(import_iovec); |
| 1839 | |
| 1840 | int import_single_range(int rw, void __user *buf, size_t len, |
| 1841 | struct iovec *iov, struct iov_iter *i) |
| 1842 | { |
| 1843 | if (len > MAX_RW_COUNT) |
| 1844 | len = MAX_RW_COUNT; |
| 1845 | if (unlikely(!access_ok(buf, len))) |
| 1846 | return -EFAULT; |
| 1847 | |
| 1848 | iov->iov_base = buf; |
| 1849 | iov->iov_len = len; |
| 1850 | iov_iter_init(i, rw, iov, 1, len); |
| 1851 | return 0; |
| 1852 | } |
| 1853 | EXPORT_SYMBOL(import_single_range); |
| 1854 | |
| 1855 | /** |
| 1856 | * iov_iter_restore() - Restore a &struct iov_iter to the same state as when |
| 1857 | * iov_iter_save_state() was called. |
| 1858 | * |
| 1859 | * @i: &struct iov_iter to restore |
| 1860 | * @state: state to restore from |
| 1861 | * |
| 1862 | * Used after iov_iter_save_state() to bring restore @i, if operations may |
| 1863 | * have advanced it. |
| 1864 | * |
| 1865 | * Note: only works on ITER_IOVEC, ITER_BVEC, and ITER_KVEC |
| 1866 | */ |
| 1867 | void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state) |
| 1868 | { |
| 1869 | if (WARN_ON_ONCE(!iov_iter_is_bvec(i) && !iter_is_iovec(i)) && |
| 1870 | !iov_iter_is_kvec(i) && !iter_is_ubuf(i)) |
| 1871 | return; |
| 1872 | i->iov_offset = state->iov_offset; |
| 1873 | i->count = state->count; |
| 1874 | if (iter_is_ubuf(i)) |
| 1875 | return; |
| 1876 | /* |
| 1877 | * For the *vec iters, nr_segs + iov is constant - if we increment |
| 1878 | * the vec, then we also decrement the nr_segs count. Hence we don't |
| 1879 | * need to track both of these, just one is enough and we can deduct |
| 1880 | * the other from that. ITER_KVEC and ITER_IOVEC are the same struct |
| 1881 | * size, so we can just increment the iov pointer as they are unionzed. |
| 1882 | * ITER_BVEC _may_ be the same size on some archs, but on others it is |
| 1883 | * not. Be safe and handle it separately. |
| 1884 | */ |
| 1885 | BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec)); |
| 1886 | if (iov_iter_is_bvec(i)) |
| 1887 | i->bvec -= state->nr_segs - i->nr_segs; |
| 1888 | else |
| 1889 | i->iov -= state->nr_segs - i->nr_segs; |
| 1890 | i->nr_segs = state->nr_segs; |
| 1891 | } |