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 #define iterate_iovec(i, n, __v, __p, skip, STEP) { \ 20 size_t left; \ 21 size_t wanted = n; \ 22 __p = i->iov; \ 23 __v.iov_len = min(n, __p->iov_len - skip); \ 24 if (likely(__v.iov_len)) { \ 25 __v.iov_base = __p->iov_base + skip; \ 26 left = (STEP); \ 27 __v.iov_len -= left; \ 28 skip += __v.iov_len; \ 29 n -= __v.iov_len; \ 30 } else { \ 31 left = 0; \ 32 } \ 33 while (unlikely(!left && n)) { \ 34 __p++; \ 35 __v.iov_len = min(n, __p->iov_len); \ 36 if (unlikely(!__v.iov_len)) \ 37 continue; \ 38 __v.iov_base = __p->iov_base; \ 39 left = (STEP); \ 40 __v.iov_len -= left; \ 41 skip = __v.iov_len; \ 42 n -= __v.iov_len; \ 43 } \ 44 n = wanted - n; \ 45 } 46 47 #define iterate_kvec(i, n, __v, __p, skip, STEP) { \ 48 size_t wanted = n; \ 49 __p = i->kvec; \ 50 __v.iov_len = min(n, __p->iov_len - skip); \ 51 if (likely(__v.iov_len)) { \ 52 __v.iov_base = __p->iov_base + skip; \ 53 (void)(STEP); \ 54 skip += __v.iov_len; \ 55 n -= __v.iov_len; \ 56 } \ 57 while (unlikely(n)) { \ 58 __p++; \ 59 __v.iov_len = min(n, __p->iov_len); \ 60 if (unlikely(!__v.iov_len)) \ 61 continue; \ 62 __v.iov_base = __p->iov_base; \ 63 (void)(STEP); \ 64 skip = __v.iov_len; \ 65 n -= __v.iov_len; \ 66 } \ 67 n = wanted; \ 68 } 69 70 #define iterate_bvec(i, n, __v, __bi, skip, STEP) { \ 71 struct bvec_iter __start; \ 72 __start.bi_size = n; \ 73 __start.bi_bvec_done = skip; \ 74 __start.bi_idx = 0; \ 75 for_each_bvec(__v, i->bvec, __bi, __start) { \ 76 (void)(STEP); \ 77 } \ 78 } 79 80 #define iterate_xarray(i, n, __v, skip, STEP) { \ 81 struct page *head = NULL; \ 82 size_t wanted = n, seg, offset; \ 83 loff_t start = i->xarray_start + skip; \ 84 pgoff_t index = start >> PAGE_SHIFT; \ 85 int j; \ 86 \ 87 XA_STATE(xas, i->xarray, index); \ 88 \ 89 rcu_read_lock(); \ 90 xas_for_each(&xas, head, ULONG_MAX) { \ 91 if (xas_retry(&xas, head)) \ 92 continue; \ 93 if (WARN_ON(xa_is_value(head))) \ 94 break; \ 95 if (WARN_ON(PageHuge(head))) \ 96 break; \ 97 for (j = (head->index < index) ? index - head->index : 0; \ 98 j < thp_nr_pages(head); j++) { \ 99 __v.bv_page = head + j; \ 100 offset = (i->xarray_start + skip) & ~PAGE_MASK; \ 101 seg = PAGE_SIZE - offset; \ 102 __v.bv_offset = offset; \ 103 __v.bv_len = min(n, seg); \ 104 (void)(STEP); \ 105 n -= __v.bv_len; \ 106 skip += __v.bv_len; \ 107 if (n == 0) \ 108 break; \ 109 } \ 110 if (n == 0) \ 111 break; \ 112 } \ 113 rcu_read_unlock(); \ 114 n = wanted - n; \ 115 } 116 117 #define iterate_all_kinds(i, n, v, I, B, K, X) { \ 118 if (likely(n)) { \ 119 size_t skip = i->iov_offset; \ 120 if (unlikely(i->type & ITER_BVEC)) { \ 121 struct bio_vec v; \ 122 struct bvec_iter __bi; \ 123 iterate_bvec(i, n, v, __bi, skip, (B)) \ 124 } else if (unlikely(i->type & ITER_KVEC)) { \ 125 const struct kvec *kvec; \ 126 struct kvec v; \ 127 iterate_kvec(i, n, v, kvec, skip, (K)) \ 128 } else if (unlikely(i->type & ITER_DISCARD)) { \ 129 } else if (unlikely(i->type & ITER_XARRAY)) { \ 130 struct bio_vec v; \ 131 iterate_xarray(i, n, v, skip, (X)); \ 132 } else { \ 133 const struct iovec *iov; \ 134 struct iovec v; \ 135 iterate_iovec(i, n, v, iov, skip, (I)) \ 136 } \ 137 } \ 138 } 139 140 #define iterate_and_advance(i, n, v, I, B, K, X) { \ 141 if (unlikely(i->count < n)) \ 142 n = i->count; \ 143 if (i->count) { \ 144 size_t skip = i->iov_offset; \ 145 if (unlikely(i->type & ITER_BVEC)) { \ 146 const struct bio_vec *bvec = i->bvec; \ 147 struct bio_vec v; \ 148 struct bvec_iter __bi; \ 149 iterate_bvec(i, n, v, __bi, skip, (B)) \ 150 i->bvec = __bvec_iter_bvec(i->bvec, __bi); \ 151 i->nr_segs -= i->bvec - bvec; \ 152 skip = __bi.bi_bvec_done; \ 153 } else if (unlikely(i->type & ITER_KVEC)) { \ 154 const struct kvec *kvec; \ 155 struct kvec v; \ 156 iterate_kvec(i, n, v, kvec, skip, (K)) \ 157 if (skip == kvec->iov_len) { \ 158 kvec++; \ 159 skip = 0; \ 160 } \ 161 i->nr_segs -= kvec - i->kvec; \ 162 i->kvec = kvec; \ 163 } else if (unlikely(i->type & ITER_DISCARD)) { \ 164 skip += n; \ 165 } else if (unlikely(i->type & ITER_XARRAY)) { \ 166 struct bio_vec v; \ 167 iterate_xarray(i, n, v, skip, (X)) \ 168 } else { \ 169 const struct iovec *iov; \ 170 struct iovec v; \ 171 iterate_iovec(i, n, v, iov, skip, (I)) \ 172 if (skip == iov->iov_len) { \ 173 iov++; \ 174 skip = 0; \ 175 } \ 176 i->nr_segs -= iov - i->iov; \ 177 i->iov = iov; \ 178 } \ 179 i->count -= n; \ 180 i->iov_offset = skip; \ 181 } \ 182 } 183 184 static int copyout(void __user *to, const void *from, size_t n) 185 { 186 if (should_fail_usercopy()) 187 return n; 188 if (access_ok(to, n)) { 189 instrument_copy_to_user(to, from, n); 190 n = raw_copy_to_user(to, from, n); 191 } 192 return n; 193 } 194 195 static int copyin(void *to, const void __user *from, size_t n) 196 { 197 if (should_fail_usercopy()) 198 return n; 199 if (access_ok(from, n)) { 200 instrument_copy_from_user(to, from, n); 201 n = raw_copy_from_user(to, from, n); 202 } 203 return n; 204 } 205 206 static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes, 207 struct iov_iter *i) 208 { 209 size_t skip, copy, left, wanted; 210 const struct iovec *iov; 211 char __user *buf; 212 void *kaddr, *from; 213 214 if (unlikely(bytes > i->count)) 215 bytes = i->count; 216 217 if (unlikely(!bytes)) 218 return 0; 219 220 might_fault(); 221 wanted = bytes; 222 iov = i->iov; 223 skip = i->iov_offset; 224 buf = iov->iov_base + skip; 225 copy = min(bytes, iov->iov_len - skip); 226 227 if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_writeable(buf, copy)) { 228 kaddr = kmap_atomic(page); 229 from = kaddr + offset; 230 231 /* first chunk, usually the only one */ 232 left = copyout(buf, from, copy); 233 copy -= left; 234 skip += copy; 235 from += copy; 236 bytes -= copy; 237 238 while (unlikely(!left && bytes)) { 239 iov++; 240 buf = iov->iov_base; 241 copy = min(bytes, iov->iov_len); 242 left = copyout(buf, from, copy); 243 copy -= left; 244 skip = copy; 245 from += copy; 246 bytes -= copy; 247 } 248 if (likely(!bytes)) { 249 kunmap_atomic(kaddr); 250 goto done; 251 } 252 offset = from - kaddr; 253 buf += copy; 254 kunmap_atomic(kaddr); 255 copy = min(bytes, iov->iov_len - skip); 256 } 257 /* Too bad - revert to non-atomic kmap */ 258 259 kaddr = kmap(page); 260 from = kaddr + offset; 261 left = copyout(buf, from, copy); 262 copy -= left; 263 skip += copy; 264 from += copy; 265 bytes -= copy; 266 while (unlikely(!left && bytes)) { 267 iov++; 268 buf = iov->iov_base; 269 copy = min(bytes, iov->iov_len); 270 left = copyout(buf, from, copy); 271 copy -= left; 272 skip = copy; 273 from += copy; 274 bytes -= copy; 275 } 276 kunmap(page); 277 278 done: 279 if (skip == iov->iov_len) { 280 iov++; 281 skip = 0; 282 } 283 i->count -= wanted - bytes; 284 i->nr_segs -= iov - i->iov; 285 i->iov = iov; 286 i->iov_offset = skip; 287 return wanted - bytes; 288 } 289 290 static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t bytes, 291 struct iov_iter *i) 292 { 293 size_t skip, copy, left, wanted; 294 const struct iovec *iov; 295 char __user *buf; 296 void *kaddr, *to; 297 298 if (unlikely(bytes > i->count)) 299 bytes = i->count; 300 301 if (unlikely(!bytes)) 302 return 0; 303 304 might_fault(); 305 wanted = bytes; 306 iov = i->iov; 307 skip = i->iov_offset; 308 buf = iov->iov_base + skip; 309 copy = min(bytes, iov->iov_len - skip); 310 311 if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_readable(buf, copy)) { 312 kaddr = kmap_atomic(page); 313 to = kaddr + offset; 314 315 /* first chunk, usually the only one */ 316 left = copyin(to, buf, copy); 317 copy -= left; 318 skip += copy; 319 to += copy; 320 bytes -= copy; 321 322 while (unlikely(!left && bytes)) { 323 iov++; 324 buf = iov->iov_base; 325 copy = min(bytes, iov->iov_len); 326 left = copyin(to, buf, copy); 327 copy -= left; 328 skip = copy; 329 to += copy; 330 bytes -= copy; 331 } 332 if (likely(!bytes)) { 333 kunmap_atomic(kaddr); 334 goto done; 335 } 336 offset = to - kaddr; 337 buf += copy; 338 kunmap_atomic(kaddr); 339 copy = min(bytes, iov->iov_len - skip); 340 } 341 /* Too bad - revert to non-atomic kmap */ 342 343 kaddr = kmap(page); 344 to = kaddr + offset; 345 left = copyin(to, buf, copy); 346 copy -= left; 347 skip += copy; 348 to += copy; 349 bytes -= copy; 350 while (unlikely(!left && bytes)) { 351 iov++; 352 buf = iov->iov_base; 353 copy = min(bytes, iov->iov_len); 354 left = copyin(to, buf, copy); 355 copy -= left; 356 skip = copy; 357 to += copy; 358 bytes -= copy; 359 } 360 kunmap(page); 361 362 done: 363 if (skip == iov->iov_len) { 364 iov++; 365 skip = 0; 366 } 367 i->count -= wanted - bytes; 368 i->nr_segs -= iov - i->iov; 369 i->iov = iov; 370 i->iov_offset = skip; 371 return wanted - bytes; 372 } 373 374 #ifdef PIPE_PARANOIA 375 static bool sanity(const struct iov_iter *i) 376 { 377 struct pipe_inode_info *pipe = i->pipe; 378 unsigned int p_head = pipe->head; 379 unsigned int p_tail = pipe->tail; 380 unsigned int p_mask = pipe->ring_size - 1; 381 unsigned int p_occupancy = pipe_occupancy(p_head, p_tail); 382 unsigned int i_head = i->head; 383 unsigned int idx; 384 385 if (i->iov_offset) { 386 struct pipe_buffer *p; 387 if (unlikely(p_occupancy == 0)) 388 goto Bad; // pipe must be non-empty 389 if (unlikely(i_head != p_head - 1)) 390 goto Bad; // must be at the last buffer... 391 392 p = &pipe->bufs[i_head & p_mask]; 393 if (unlikely(p->offset + p->len != i->iov_offset)) 394 goto Bad; // ... at the end of segment 395 } else { 396 if (i_head != p_head) 397 goto Bad; // must be right after the last buffer 398 } 399 return true; 400 Bad: 401 printk(KERN_ERR "idx = %d, offset = %zd\n", i_head, i->iov_offset); 402 printk(KERN_ERR "head = %d, tail = %d, buffers = %d\n", 403 p_head, p_tail, pipe->ring_size); 404 for (idx = 0; idx < pipe->ring_size; idx++) 405 printk(KERN_ERR "[%p %p %d %d]\n", 406 pipe->bufs[idx].ops, 407 pipe->bufs[idx].page, 408 pipe->bufs[idx].offset, 409 pipe->bufs[idx].len); 410 WARN_ON(1); 411 return false; 412 } 413 #else 414 #define sanity(i) true 415 #endif 416 417 static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes, 418 struct iov_iter *i) 419 { 420 struct pipe_inode_info *pipe = i->pipe; 421 struct pipe_buffer *buf; 422 unsigned int p_tail = pipe->tail; 423 unsigned int p_mask = pipe->ring_size - 1; 424 unsigned int i_head = i->head; 425 size_t off; 426 427 if (unlikely(bytes > i->count)) 428 bytes = i->count; 429 430 if (unlikely(!bytes)) 431 return 0; 432 433 if (!sanity(i)) 434 return 0; 435 436 off = i->iov_offset; 437 buf = &pipe->bufs[i_head & p_mask]; 438 if (off) { 439 if (offset == off && buf->page == page) { 440 /* merge with the last one */ 441 buf->len += bytes; 442 i->iov_offset += bytes; 443 goto out; 444 } 445 i_head++; 446 buf = &pipe->bufs[i_head & p_mask]; 447 } 448 if (pipe_full(i_head, p_tail, pipe->max_usage)) 449 return 0; 450 451 buf->ops = &page_cache_pipe_buf_ops; 452 get_page(page); 453 buf->page = page; 454 buf->offset = offset; 455 buf->len = bytes; 456 457 pipe->head = i_head + 1; 458 i->iov_offset = offset + bytes; 459 i->head = i_head; 460 out: 461 i->count -= bytes; 462 return bytes; 463 } 464 465 /* 466 * Fault in one or more iovecs of the given iov_iter, to a maximum length of 467 * bytes. For each iovec, fault in each page that constitutes the iovec. 468 * 469 * Return 0 on success, or non-zero if the memory could not be accessed (i.e. 470 * because it is an invalid address). 471 */ 472 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) 473 { 474 size_t skip = i->iov_offset; 475 const struct iovec *iov; 476 int err; 477 struct iovec v; 478 479 if (!(i->type & (ITER_BVEC|ITER_KVEC))) { 480 iterate_iovec(i, bytes, v, iov, skip, ({ 481 err = fault_in_pages_readable(v.iov_base, v.iov_len); 482 if (unlikely(err)) 483 return err; 484 0;})) 485 } 486 return 0; 487 } 488 EXPORT_SYMBOL(iov_iter_fault_in_readable); 489 490 void iov_iter_init(struct iov_iter *i, unsigned int direction, 491 const struct iovec *iov, unsigned long nr_segs, 492 size_t count) 493 { 494 WARN_ON(direction & ~(READ | WRITE)); 495 direction &= READ | WRITE; 496 497 /* It will get better. Eventually... */ 498 if (uaccess_kernel()) { 499 i->type = ITER_KVEC | direction; 500 i->kvec = (struct kvec *)iov; 501 } else { 502 i->type = ITER_IOVEC | direction; 503 i->iov = iov; 504 } 505 i->nr_segs = nr_segs; 506 i->iov_offset = 0; 507 i->count = count; 508 } 509 EXPORT_SYMBOL(iov_iter_init); 510 511 static inline bool allocated(struct pipe_buffer *buf) 512 { 513 return buf->ops == &default_pipe_buf_ops; 514 } 515 516 static inline void data_start(const struct iov_iter *i, 517 unsigned int *iter_headp, size_t *offp) 518 { 519 unsigned int p_mask = i->pipe->ring_size - 1; 520 unsigned int iter_head = i->head; 521 size_t off = i->iov_offset; 522 523 if (off && (!allocated(&i->pipe->bufs[iter_head & p_mask]) || 524 off == PAGE_SIZE)) { 525 iter_head++; 526 off = 0; 527 } 528 *iter_headp = iter_head; 529 *offp = off; 530 } 531 532 static size_t push_pipe(struct iov_iter *i, size_t size, 533 int *iter_headp, size_t *offp) 534 { 535 struct pipe_inode_info *pipe = i->pipe; 536 unsigned int p_tail = pipe->tail; 537 unsigned int p_mask = pipe->ring_size - 1; 538 unsigned int iter_head; 539 size_t off; 540 ssize_t left; 541 542 if (unlikely(size > i->count)) 543 size = i->count; 544 if (unlikely(!size)) 545 return 0; 546 547 left = size; 548 data_start(i, &iter_head, &off); 549 *iter_headp = iter_head; 550 *offp = off; 551 if (off) { 552 left -= PAGE_SIZE - off; 553 if (left <= 0) { 554 pipe->bufs[iter_head & p_mask].len += size; 555 return size; 556 } 557 pipe->bufs[iter_head & p_mask].len = PAGE_SIZE; 558 iter_head++; 559 } 560 while (!pipe_full(iter_head, p_tail, pipe->max_usage)) { 561 struct pipe_buffer *buf = &pipe->bufs[iter_head & p_mask]; 562 struct page *page = alloc_page(GFP_USER); 563 if (!page) 564 break; 565 566 buf->ops = &default_pipe_buf_ops; 567 buf->page = page; 568 buf->offset = 0; 569 buf->len = min_t(ssize_t, left, PAGE_SIZE); 570 left -= buf->len; 571 iter_head++; 572 pipe->head = iter_head; 573 574 if (left == 0) 575 return size; 576 } 577 return size - left; 578 } 579 580 static size_t copy_pipe_to_iter(const void *addr, size_t bytes, 581 struct iov_iter *i) 582 { 583 struct pipe_inode_info *pipe = i->pipe; 584 unsigned int p_mask = pipe->ring_size - 1; 585 unsigned int i_head; 586 size_t n, off; 587 588 if (!sanity(i)) 589 return 0; 590 591 bytes = n = push_pipe(i, bytes, &i_head, &off); 592 if (unlikely(!n)) 593 return 0; 594 do { 595 size_t chunk = min_t(size_t, n, PAGE_SIZE - off); 596 memcpy_to_page(pipe->bufs[i_head & p_mask].page, off, addr, chunk); 597 i->head = i_head; 598 i->iov_offset = off + chunk; 599 n -= chunk; 600 addr += chunk; 601 off = 0; 602 i_head++; 603 } while (n); 604 i->count -= bytes; 605 return bytes; 606 } 607 608 static __wsum csum_and_memcpy(void *to, const void *from, size_t len, 609 __wsum sum, size_t off) 610 { 611 __wsum next = csum_partial_copy_nocheck(from, to, len); 612 return csum_block_add(sum, next, off); 613 } 614 615 static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes, 616 struct csum_state *csstate, 617 struct iov_iter *i) 618 { 619 struct pipe_inode_info *pipe = i->pipe; 620 unsigned int p_mask = pipe->ring_size - 1; 621 __wsum sum = csstate->csum; 622 size_t off = csstate->off; 623 unsigned int i_head; 624 size_t n, r; 625 626 if (!sanity(i)) 627 return 0; 628 629 bytes = n = push_pipe(i, bytes, &i_head, &r); 630 if (unlikely(!n)) 631 return 0; 632 do { 633 size_t chunk = min_t(size_t, n, PAGE_SIZE - r); 634 char *p = kmap_atomic(pipe->bufs[i_head & p_mask].page); 635 sum = csum_and_memcpy(p + r, addr, chunk, sum, off); 636 kunmap_atomic(p); 637 i->head = i_head; 638 i->iov_offset = r + chunk; 639 n -= chunk; 640 off += chunk; 641 addr += chunk; 642 r = 0; 643 i_head++; 644 } while (n); 645 i->count -= bytes; 646 csstate->csum = sum; 647 csstate->off = off; 648 return bytes; 649 } 650 651 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i) 652 { 653 const char *from = addr; 654 if (unlikely(iov_iter_is_pipe(i))) 655 return copy_pipe_to_iter(addr, bytes, i); 656 if (iter_is_iovec(i)) 657 might_fault(); 658 iterate_and_advance(i, bytes, v, 659 copyout(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len), 660 memcpy_to_page(v.bv_page, v.bv_offset, 661 (from += v.bv_len) - v.bv_len, v.bv_len), 662 memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len), 663 memcpy_to_page(v.bv_page, v.bv_offset, 664 (from += v.bv_len) - v.bv_len, v.bv_len) 665 ) 666 667 return bytes; 668 } 669 EXPORT_SYMBOL(_copy_to_iter); 670 671 #ifdef CONFIG_ARCH_HAS_COPY_MC 672 static int copyout_mc(void __user *to, const void *from, size_t n) 673 { 674 if (access_ok(to, n)) { 675 instrument_copy_to_user(to, from, n); 676 n = copy_mc_to_user((__force void *) to, from, n); 677 } 678 return n; 679 } 680 681 static unsigned long copy_mc_to_page(struct page *page, size_t offset, 682 const char *from, size_t len) 683 { 684 unsigned long ret; 685 char *to; 686 687 to = kmap_atomic(page); 688 ret = copy_mc_to_kernel(to + offset, from, len); 689 kunmap_atomic(to); 690 691 return ret; 692 } 693 694 static size_t copy_mc_pipe_to_iter(const void *addr, size_t bytes, 695 struct iov_iter *i) 696 { 697 struct pipe_inode_info *pipe = i->pipe; 698 unsigned int p_mask = pipe->ring_size - 1; 699 unsigned int i_head; 700 size_t n, off, xfer = 0; 701 702 if (!sanity(i)) 703 return 0; 704 705 bytes = n = push_pipe(i, bytes, &i_head, &off); 706 if (unlikely(!n)) 707 return 0; 708 do { 709 size_t chunk = min_t(size_t, n, PAGE_SIZE - off); 710 unsigned long rem; 711 712 rem = copy_mc_to_page(pipe->bufs[i_head & p_mask].page, 713 off, addr, chunk); 714 i->head = i_head; 715 i->iov_offset = off + chunk - rem; 716 xfer += chunk - rem; 717 if (rem) 718 break; 719 n -= chunk; 720 addr += chunk; 721 off = 0; 722 i_head++; 723 } while (n); 724 i->count -= xfer; 725 return xfer; 726 } 727 728 /** 729 * _copy_mc_to_iter - copy to iter with source memory error exception handling 730 * @addr: source kernel address 731 * @bytes: total transfer length 732 * @iter: destination iterator 733 * 734 * The pmem driver deploys this for the dax operation 735 * (dax_copy_to_iter()) for dax reads (bypass page-cache and the 736 * block-layer). Upon #MC read(2) aborts and returns EIO or the bytes 737 * successfully copied. 738 * 739 * The main differences between this and typical _copy_to_iter(). 740 * 741 * * Typical tail/residue handling after a fault retries the copy 742 * byte-by-byte until the fault happens again. Re-triggering machine 743 * checks is potentially fatal so the implementation uses source 744 * alignment and poison alignment assumptions to avoid re-triggering 745 * hardware exceptions. 746 * 747 * * ITER_KVEC, ITER_PIPE, and ITER_BVEC can return short copies. 748 * Compare to copy_to_iter() where only ITER_IOVEC attempts might return 749 * a short copy. 750 */ 751 size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i) 752 { 753 const char *from = addr; 754 unsigned long rem, curr_addr, s_addr = (unsigned long) addr; 755 756 if (unlikely(iov_iter_is_pipe(i))) 757 return copy_mc_pipe_to_iter(addr, bytes, i); 758 if (iter_is_iovec(i)) 759 might_fault(); 760 iterate_and_advance(i, bytes, v, 761 copyout_mc(v.iov_base, (from += v.iov_len) - v.iov_len, 762 v.iov_len), 763 ({ 764 rem = copy_mc_to_page(v.bv_page, v.bv_offset, 765 (from += v.bv_len) - v.bv_len, v.bv_len); 766 if (rem) { 767 curr_addr = (unsigned long) from; 768 bytes = curr_addr - s_addr - rem; 769 return bytes; 770 } 771 }), 772 ({ 773 rem = copy_mc_to_kernel(v.iov_base, (from += v.iov_len) 774 - v.iov_len, v.iov_len); 775 if (rem) { 776 curr_addr = (unsigned long) from; 777 bytes = curr_addr - s_addr - rem; 778 return bytes; 779 } 780 }), 781 ({ 782 rem = copy_mc_to_page(v.bv_page, v.bv_offset, 783 (from += v.bv_len) - v.bv_len, v.bv_len); 784 if (rem) { 785 curr_addr = (unsigned long) from; 786 bytes = curr_addr - s_addr - rem; 787 rcu_read_unlock(); 788 i->iov_offset += bytes; 789 i->count -= bytes; 790 return bytes; 791 } 792 }) 793 ) 794 795 return bytes; 796 } 797 EXPORT_SYMBOL_GPL(_copy_mc_to_iter); 798 #endif /* CONFIG_ARCH_HAS_COPY_MC */ 799 800 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) 801 { 802 char *to = addr; 803 if (unlikely(iov_iter_is_pipe(i))) { 804 WARN_ON(1); 805 return 0; 806 } 807 if (iter_is_iovec(i)) 808 might_fault(); 809 iterate_and_advance(i, bytes, v, 810 copyin((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), 811 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page, 812 v.bv_offset, v.bv_len), 813 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), 814 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page, 815 v.bv_offset, v.bv_len) 816 ) 817 818 return bytes; 819 } 820 EXPORT_SYMBOL(_copy_from_iter); 821 822 bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i) 823 { 824 char *to = addr; 825 if (unlikely(iov_iter_is_pipe(i))) { 826 WARN_ON(1); 827 return false; 828 } 829 if (unlikely(i->count < bytes)) 830 return false; 831 832 if (iter_is_iovec(i)) 833 might_fault(); 834 iterate_all_kinds(i, bytes, v, ({ 835 if (copyin((to += v.iov_len) - v.iov_len, 836 v.iov_base, v.iov_len)) 837 return false; 838 0;}), 839 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page, 840 v.bv_offset, v.bv_len), 841 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), 842 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page, 843 v.bv_offset, v.bv_len) 844 ) 845 846 iov_iter_advance(i, bytes); 847 return true; 848 } 849 EXPORT_SYMBOL(_copy_from_iter_full); 850 851 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i) 852 { 853 char *to = addr; 854 if (unlikely(iov_iter_is_pipe(i))) { 855 WARN_ON(1); 856 return 0; 857 } 858 iterate_and_advance(i, bytes, v, 859 __copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len, 860 v.iov_base, v.iov_len), 861 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page, 862 v.bv_offset, v.bv_len), 863 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), 864 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page, 865 v.bv_offset, v.bv_len) 866 ) 867 868 return bytes; 869 } 870 EXPORT_SYMBOL(_copy_from_iter_nocache); 871 872 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE 873 /** 874 * _copy_from_iter_flushcache - write destination through cpu cache 875 * @addr: destination kernel address 876 * @bytes: total transfer length 877 * @iter: source iterator 878 * 879 * The pmem driver arranges for filesystem-dax to use this facility via 880 * dax_copy_from_iter() for ensuring that writes to persistent memory 881 * are flushed through the CPU cache. It is differentiated from 882 * _copy_from_iter_nocache() in that guarantees all data is flushed for 883 * all iterator types. The _copy_from_iter_nocache() only attempts to 884 * bypass the cache for the ITER_IOVEC case, and on some archs may use 885 * instructions that strand dirty-data in the cache. 886 */ 887 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i) 888 { 889 char *to = addr; 890 if (unlikely(iov_iter_is_pipe(i))) { 891 WARN_ON(1); 892 return 0; 893 } 894 iterate_and_advance(i, bytes, v, 895 __copy_from_user_flushcache((to += v.iov_len) - v.iov_len, 896 v.iov_base, v.iov_len), 897 memcpy_page_flushcache((to += v.bv_len) - v.bv_len, v.bv_page, 898 v.bv_offset, v.bv_len), 899 memcpy_flushcache((to += v.iov_len) - v.iov_len, v.iov_base, 900 v.iov_len), 901 memcpy_page_flushcache((to += v.bv_len) - v.bv_len, v.bv_page, 902 v.bv_offset, v.bv_len) 903 ) 904 905 return bytes; 906 } 907 EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache); 908 #endif 909 910 bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i) 911 { 912 char *to = addr; 913 if (unlikely(iov_iter_is_pipe(i))) { 914 WARN_ON(1); 915 return false; 916 } 917 if (unlikely(i->count < bytes)) 918 return false; 919 iterate_all_kinds(i, bytes, v, ({ 920 if (__copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len, 921 v.iov_base, v.iov_len)) 922 return false; 923 0;}), 924 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page, 925 v.bv_offset, v.bv_len), 926 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), 927 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page, 928 v.bv_offset, v.bv_len) 929 ) 930 931 iov_iter_advance(i, bytes); 932 return true; 933 } 934 EXPORT_SYMBOL(_copy_from_iter_full_nocache); 935 936 static inline bool page_copy_sane(struct page *page, size_t offset, size_t n) 937 { 938 struct page *head; 939 size_t v = n + offset; 940 941 /* 942 * The general case needs to access the page order in order 943 * to compute the page size. 944 * However, we mostly deal with order-0 pages and thus can 945 * avoid a possible cache line miss for requests that fit all 946 * page orders. 947 */ 948 if (n <= v && v <= PAGE_SIZE) 949 return true; 950 951 head = compound_head(page); 952 v += (page - head) << PAGE_SHIFT; 953 954 if (likely(n <= v && v <= (page_size(head)))) 955 return true; 956 WARN_ON(1); 957 return false; 958 } 959 960 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, 961 struct iov_iter *i) 962 { 963 if (unlikely(!page_copy_sane(page, offset, bytes))) 964 return 0; 965 if (i->type & (ITER_BVEC | ITER_KVEC | ITER_XARRAY)) { 966 void *kaddr = kmap_atomic(page); 967 size_t wanted = copy_to_iter(kaddr + offset, bytes, i); 968 kunmap_atomic(kaddr); 969 return wanted; 970 } else if (unlikely(iov_iter_is_discard(i))) 971 return bytes; 972 else if (likely(!iov_iter_is_pipe(i))) 973 return copy_page_to_iter_iovec(page, offset, bytes, i); 974 else 975 return copy_page_to_iter_pipe(page, offset, bytes, i); 976 } 977 EXPORT_SYMBOL(copy_page_to_iter); 978 979 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, 980 struct iov_iter *i) 981 { 982 if (unlikely(!page_copy_sane(page, offset, bytes))) 983 return 0; 984 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { 985 WARN_ON(1); 986 return 0; 987 } 988 if (i->type & (ITER_BVEC | ITER_KVEC | ITER_XARRAY)) { 989 void *kaddr = kmap_atomic(page); 990 size_t wanted = _copy_from_iter(kaddr + offset, bytes, i); 991 kunmap_atomic(kaddr); 992 return wanted; 993 } else 994 return copy_page_from_iter_iovec(page, offset, bytes, i); 995 } 996 EXPORT_SYMBOL(copy_page_from_iter); 997 998 static size_t pipe_zero(size_t bytes, struct iov_iter *i) 999 { 1000 struct pipe_inode_info *pipe = i->pipe; 1001 unsigned int p_mask = pipe->ring_size - 1; 1002 unsigned int i_head; 1003 size_t n, off; 1004 1005 if (!sanity(i)) 1006 return 0; 1007 1008 bytes = n = push_pipe(i, bytes, &i_head, &off); 1009 if (unlikely(!n)) 1010 return 0; 1011 1012 do { 1013 size_t chunk = min_t(size_t, n, PAGE_SIZE - off); 1014 memzero_page(pipe->bufs[i_head & p_mask].page, off, chunk); 1015 i->head = i_head; 1016 i->iov_offset = off + chunk; 1017 n -= chunk; 1018 off = 0; 1019 i_head++; 1020 } while (n); 1021 i->count -= bytes; 1022 return bytes; 1023 } 1024 1025 size_t iov_iter_zero(size_t bytes, struct iov_iter *i) 1026 { 1027 if (unlikely(iov_iter_is_pipe(i))) 1028 return pipe_zero(bytes, i); 1029 iterate_and_advance(i, bytes, v, 1030 clear_user(v.iov_base, v.iov_len), 1031 memzero_page(v.bv_page, v.bv_offset, v.bv_len), 1032 memset(v.iov_base, 0, v.iov_len), 1033 memzero_page(v.bv_page, v.bv_offset, v.bv_len) 1034 ) 1035 1036 return bytes; 1037 } 1038 EXPORT_SYMBOL(iov_iter_zero); 1039 1040 size_t iov_iter_copy_from_user_atomic(struct page *page, 1041 struct iov_iter *i, unsigned long offset, size_t bytes) 1042 { 1043 char *kaddr = kmap_atomic(page), *p = kaddr + offset; 1044 if (unlikely(!page_copy_sane(page, offset, bytes))) { 1045 kunmap_atomic(kaddr); 1046 return 0; 1047 } 1048 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { 1049 kunmap_atomic(kaddr); 1050 WARN_ON(1); 1051 return 0; 1052 } 1053 iterate_all_kinds(i, bytes, v, 1054 copyin((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), 1055 memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page, 1056 v.bv_offset, v.bv_len), 1057 memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), 1058 memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page, 1059 v.bv_offset, v.bv_len) 1060 ) 1061 kunmap_atomic(kaddr); 1062 return bytes; 1063 } 1064 EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); 1065 1066 static inline void pipe_truncate(struct iov_iter *i) 1067 { 1068 struct pipe_inode_info *pipe = i->pipe; 1069 unsigned int p_tail = pipe->tail; 1070 unsigned int p_head = pipe->head; 1071 unsigned int p_mask = pipe->ring_size - 1; 1072 1073 if (!pipe_empty(p_head, p_tail)) { 1074 struct pipe_buffer *buf; 1075 unsigned int i_head = i->head; 1076 size_t off = i->iov_offset; 1077 1078 if (off) { 1079 buf = &pipe->bufs[i_head & p_mask]; 1080 buf->len = off - buf->offset; 1081 i_head++; 1082 } 1083 while (p_head != i_head) { 1084 p_head--; 1085 pipe_buf_release(pipe, &pipe->bufs[p_head & p_mask]); 1086 } 1087 1088 pipe->head = p_head; 1089 } 1090 } 1091 1092 static void pipe_advance(struct iov_iter *i, size_t size) 1093 { 1094 struct pipe_inode_info *pipe = i->pipe; 1095 if (unlikely(i->count < size)) 1096 size = i->count; 1097 if (size) { 1098 struct pipe_buffer *buf; 1099 unsigned int p_mask = pipe->ring_size - 1; 1100 unsigned int i_head = i->head; 1101 size_t off = i->iov_offset, left = size; 1102 1103 if (off) /* make it relative to the beginning of buffer */ 1104 left += off - pipe->bufs[i_head & p_mask].offset; 1105 while (1) { 1106 buf = &pipe->bufs[i_head & p_mask]; 1107 if (left <= buf->len) 1108 break; 1109 left -= buf->len; 1110 i_head++; 1111 } 1112 i->head = i_head; 1113 i->iov_offset = buf->offset + left; 1114 } 1115 i->count -= size; 1116 /* ... and discard everything past that point */ 1117 pipe_truncate(i); 1118 } 1119 1120 static void iov_iter_bvec_advance(struct iov_iter *i, size_t size) 1121 { 1122 struct bvec_iter bi; 1123 1124 bi.bi_size = i->count; 1125 bi.bi_bvec_done = i->iov_offset; 1126 bi.bi_idx = 0; 1127 bvec_iter_advance(i->bvec, &bi, size); 1128 1129 i->bvec += bi.bi_idx; 1130 i->nr_segs -= bi.bi_idx; 1131 i->count = bi.bi_size; 1132 i->iov_offset = bi.bi_bvec_done; 1133 } 1134 1135 void iov_iter_advance(struct iov_iter *i, size_t size) 1136 { 1137 if (unlikely(iov_iter_is_pipe(i))) { 1138 pipe_advance(i, size); 1139 return; 1140 } 1141 if (unlikely(iov_iter_is_discard(i))) { 1142 i->count -= size; 1143 return; 1144 } 1145 if (unlikely(iov_iter_is_xarray(i))) { 1146 size = min(size, i->count); 1147 i->iov_offset += size; 1148 i->count -= size; 1149 return; 1150 } 1151 if (iov_iter_is_bvec(i)) { 1152 iov_iter_bvec_advance(i, size); 1153 return; 1154 } 1155 iterate_and_advance(i, size, v, 0, 0, 0, 0) 1156 } 1157 EXPORT_SYMBOL(iov_iter_advance); 1158 1159 void iov_iter_revert(struct iov_iter *i, size_t unroll) 1160 { 1161 if (!unroll) 1162 return; 1163 if (WARN_ON(unroll > MAX_RW_COUNT)) 1164 return; 1165 i->count += unroll; 1166 if (unlikely(iov_iter_is_pipe(i))) { 1167 struct pipe_inode_info *pipe = i->pipe; 1168 unsigned int p_mask = pipe->ring_size - 1; 1169 unsigned int i_head = i->head; 1170 size_t off = i->iov_offset; 1171 while (1) { 1172 struct pipe_buffer *b = &pipe->bufs[i_head & p_mask]; 1173 size_t n = off - b->offset; 1174 if (unroll < n) { 1175 off -= unroll; 1176 break; 1177 } 1178 unroll -= n; 1179 if (!unroll && i_head == i->start_head) { 1180 off = 0; 1181 break; 1182 } 1183 i_head--; 1184 b = &pipe->bufs[i_head & p_mask]; 1185 off = b->offset + b->len; 1186 } 1187 i->iov_offset = off; 1188 i->head = i_head; 1189 pipe_truncate(i); 1190 return; 1191 } 1192 if (unlikely(iov_iter_is_discard(i))) 1193 return; 1194 if (unroll <= i->iov_offset) { 1195 i->iov_offset -= unroll; 1196 return; 1197 } 1198 unroll -= i->iov_offset; 1199 if (iov_iter_is_xarray(i)) { 1200 BUG(); /* We should never go beyond the start of the specified 1201 * range since we might then be straying into pages that 1202 * aren't pinned. 1203 */ 1204 } else if (iov_iter_is_bvec(i)) { 1205 const struct bio_vec *bvec = i->bvec; 1206 while (1) { 1207 size_t n = (--bvec)->bv_len; 1208 i->nr_segs++; 1209 if (unroll <= n) { 1210 i->bvec = bvec; 1211 i->iov_offset = n - unroll; 1212 return; 1213 } 1214 unroll -= n; 1215 } 1216 } else { /* same logics for iovec and kvec */ 1217 const struct iovec *iov = i->iov; 1218 while (1) { 1219 size_t n = (--iov)->iov_len; 1220 i->nr_segs++; 1221 if (unroll <= n) { 1222 i->iov = iov; 1223 i->iov_offset = n - unroll; 1224 return; 1225 } 1226 unroll -= n; 1227 } 1228 } 1229 } 1230 EXPORT_SYMBOL(iov_iter_revert); 1231 1232 /* 1233 * Return the count of just the current iov_iter segment. 1234 */ 1235 size_t iov_iter_single_seg_count(const struct iov_iter *i) 1236 { 1237 if (unlikely(iov_iter_is_pipe(i))) 1238 return i->count; // it is a silly place, anyway 1239 if (i->nr_segs == 1) 1240 return i->count; 1241 if (unlikely(iov_iter_is_discard(i) || iov_iter_is_xarray(i))) 1242 return i->count; 1243 if (iov_iter_is_bvec(i)) 1244 return min(i->count, i->bvec->bv_len - i->iov_offset); 1245 else 1246 return min(i->count, i->iov->iov_len - i->iov_offset); 1247 } 1248 EXPORT_SYMBOL(iov_iter_single_seg_count); 1249 1250 void iov_iter_kvec(struct iov_iter *i, unsigned int direction, 1251 const struct kvec *kvec, unsigned long nr_segs, 1252 size_t count) 1253 { 1254 WARN_ON(direction & ~(READ | WRITE)); 1255 i->type = ITER_KVEC | (direction & (READ | WRITE)); 1256 i->kvec = kvec; 1257 i->nr_segs = nr_segs; 1258 i->iov_offset = 0; 1259 i->count = count; 1260 } 1261 EXPORT_SYMBOL(iov_iter_kvec); 1262 1263 void iov_iter_bvec(struct iov_iter *i, unsigned int direction, 1264 const struct bio_vec *bvec, unsigned long nr_segs, 1265 size_t count) 1266 { 1267 WARN_ON(direction & ~(READ | WRITE)); 1268 i->type = ITER_BVEC | (direction & (READ | WRITE)); 1269 i->bvec = bvec; 1270 i->nr_segs = nr_segs; 1271 i->iov_offset = 0; 1272 i->count = count; 1273 } 1274 EXPORT_SYMBOL(iov_iter_bvec); 1275 1276 void iov_iter_pipe(struct iov_iter *i, unsigned int direction, 1277 struct pipe_inode_info *pipe, 1278 size_t count) 1279 { 1280 BUG_ON(direction != READ); 1281 WARN_ON(pipe_full(pipe->head, pipe->tail, pipe->ring_size)); 1282 i->type = ITER_PIPE | READ; 1283 i->pipe = pipe; 1284 i->head = pipe->head; 1285 i->iov_offset = 0; 1286 i->count = count; 1287 i->start_head = i->head; 1288 } 1289 EXPORT_SYMBOL(iov_iter_pipe); 1290 1291 /** 1292 * iov_iter_xarray - Initialise an I/O iterator to use the pages in an xarray 1293 * @i: The iterator to initialise. 1294 * @direction: The direction of the transfer. 1295 * @xarray: The xarray to access. 1296 * @start: The start file position. 1297 * @count: The size of the I/O buffer in bytes. 1298 * 1299 * Set up an I/O iterator to either draw data out of the pages attached to an 1300 * inode or to inject data into those pages. The pages *must* be prevented 1301 * from evaporation, either by taking a ref on them or locking them by the 1302 * caller. 1303 */ 1304 void iov_iter_xarray(struct iov_iter *i, unsigned int direction, 1305 struct xarray *xarray, loff_t start, size_t count) 1306 { 1307 BUG_ON(direction & ~1); 1308 i->type = ITER_XARRAY | (direction & (READ | WRITE)); 1309 i->xarray = xarray; 1310 i->xarray_start = start; 1311 i->count = count; 1312 i->iov_offset = 0; 1313 } 1314 EXPORT_SYMBOL(iov_iter_xarray); 1315 1316 /** 1317 * iov_iter_discard - Initialise an I/O iterator that discards data 1318 * @i: The iterator to initialise. 1319 * @direction: The direction of the transfer. 1320 * @count: The size of the I/O buffer in bytes. 1321 * 1322 * Set up an I/O iterator that just discards everything that's written to it. 1323 * It's only available as a READ iterator. 1324 */ 1325 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count) 1326 { 1327 BUG_ON(direction != READ); 1328 i->type = ITER_DISCARD | READ; 1329 i->count = count; 1330 i->iov_offset = 0; 1331 } 1332 EXPORT_SYMBOL(iov_iter_discard); 1333 1334 unsigned long iov_iter_alignment(const struct iov_iter *i) 1335 { 1336 unsigned long res = 0; 1337 size_t size = i->count; 1338 1339 if (unlikely(iov_iter_is_pipe(i))) { 1340 unsigned int p_mask = i->pipe->ring_size - 1; 1341 1342 if (size && i->iov_offset && allocated(&i->pipe->bufs[i->head & p_mask])) 1343 return size | i->iov_offset; 1344 return size; 1345 } 1346 if (unlikely(iov_iter_is_xarray(i))) 1347 return (i->xarray_start + i->iov_offset) | i->count; 1348 iterate_all_kinds(i, size, v, 1349 (res |= (unsigned long)v.iov_base | v.iov_len, 0), 1350 res |= v.bv_offset | v.bv_len, 1351 res |= (unsigned long)v.iov_base | v.iov_len, 1352 res |= v.bv_offset | v.bv_len 1353 ) 1354 return res; 1355 } 1356 EXPORT_SYMBOL(iov_iter_alignment); 1357 1358 unsigned long iov_iter_gap_alignment(const struct iov_iter *i) 1359 { 1360 unsigned long res = 0; 1361 size_t size = i->count; 1362 1363 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { 1364 WARN_ON(1); 1365 return ~0U; 1366 } 1367 1368 iterate_all_kinds(i, size, v, 1369 (res |= (!res ? 0 : (unsigned long)v.iov_base) | 1370 (size != v.iov_len ? size : 0), 0), 1371 (res |= (!res ? 0 : (unsigned long)v.bv_offset) | 1372 (size != v.bv_len ? size : 0)), 1373 (res |= (!res ? 0 : (unsigned long)v.iov_base) | 1374 (size != v.iov_len ? size : 0)), 1375 (res |= (!res ? 0 : (unsigned long)v.bv_offset) | 1376 (size != v.bv_len ? size : 0)) 1377 ); 1378 return res; 1379 } 1380 EXPORT_SYMBOL(iov_iter_gap_alignment); 1381 1382 static inline ssize_t __pipe_get_pages(struct iov_iter *i, 1383 size_t maxsize, 1384 struct page **pages, 1385 int iter_head, 1386 size_t *start) 1387 { 1388 struct pipe_inode_info *pipe = i->pipe; 1389 unsigned int p_mask = pipe->ring_size - 1; 1390 ssize_t n = push_pipe(i, maxsize, &iter_head, start); 1391 if (!n) 1392 return -EFAULT; 1393 1394 maxsize = n; 1395 n += *start; 1396 while (n > 0) { 1397 get_page(*pages++ = pipe->bufs[iter_head & p_mask].page); 1398 iter_head++; 1399 n -= PAGE_SIZE; 1400 } 1401 1402 return maxsize; 1403 } 1404 1405 static ssize_t pipe_get_pages(struct iov_iter *i, 1406 struct page **pages, size_t maxsize, unsigned maxpages, 1407 size_t *start) 1408 { 1409 unsigned int iter_head, npages; 1410 size_t capacity; 1411 1412 if (!maxsize) 1413 return 0; 1414 1415 if (!sanity(i)) 1416 return -EFAULT; 1417 1418 data_start(i, &iter_head, start); 1419 /* Amount of free space: some of this one + all after this one */ 1420 npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe); 1421 capacity = min(npages, maxpages) * PAGE_SIZE - *start; 1422 1423 return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start); 1424 } 1425 1426 static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa, 1427 pgoff_t index, unsigned int nr_pages) 1428 { 1429 XA_STATE(xas, xa, index); 1430 struct page *page; 1431 unsigned int ret = 0; 1432 1433 rcu_read_lock(); 1434 for (page = xas_load(&xas); page; page = xas_next(&xas)) { 1435 if (xas_retry(&xas, page)) 1436 continue; 1437 1438 /* Has the page moved or been split? */ 1439 if (unlikely(page != xas_reload(&xas))) { 1440 xas_reset(&xas); 1441 continue; 1442 } 1443 1444 pages[ret] = find_subpage(page, xas.xa_index); 1445 get_page(pages[ret]); 1446 if (++ret == nr_pages) 1447 break; 1448 } 1449 rcu_read_unlock(); 1450 return ret; 1451 } 1452 1453 static ssize_t iter_xarray_get_pages(struct iov_iter *i, 1454 struct page **pages, size_t maxsize, 1455 unsigned maxpages, size_t *_start_offset) 1456 { 1457 unsigned nr, offset; 1458 pgoff_t index, count; 1459 size_t size = maxsize, actual; 1460 loff_t pos; 1461 1462 if (!size || !maxpages) 1463 return 0; 1464 1465 pos = i->xarray_start + i->iov_offset; 1466 index = pos >> PAGE_SHIFT; 1467 offset = pos & ~PAGE_MASK; 1468 *_start_offset = offset; 1469 1470 count = 1; 1471 if (size > PAGE_SIZE - offset) { 1472 size -= PAGE_SIZE - offset; 1473 count += size >> PAGE_SHIFT; 1474 size &= ~PAGE_MASK; 1475 if (size) 1476 count++; 1477 } 1478 1479 if (count > maxpages) 1480 count = maxpages; 1481 1482 nr = iter_xarray_populate_pages(pages, i->xarray, index, count); 1483 if (nr == 0) 1484 return 0; 1485 1486 actual = PAGE_SIZE * nr; 1487 actual -= offset; 1488 if (nr == count && size > 0) { 1489 unsigned last_offset = (nr > 1) ? 0 : offset; 1490 actual -= PAGE_SIZE - (last_offset + size); 1491 } 1492 return actual; 1493 } 1494 1495 ssize_t iov_iter_get_pages(struct iov_iter *i, 1496 struct page **pages, size_t maxsize, unsigned maxpages, 1497 size_t *start) 1498 { 1499 if (maxsize > i->count) 1500 maxsize = i->count; 1501 1502 if (unlikely(iov_iter_is_pipe(i))) 1503 return pipe_get_pages(i, pages, maxsize, maxpages, start); 1504 if (unlikely(iov_iter_is_xarray(i))) 1505 return iter_xarray_get_pages(i, pages, maxsize, maxpages, start); 1506 if (unlikely(iov_iter_is_discard(i))) 1507 return -EFAULT; 1508 1509 iterate_all_kinds(i, maxsize, v, ({ 1510 unsigned long addr = (unsigned long)v.iov_base; 1511 size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1)); 1512 int n; 1513 int res; 1514 1515 if (len > maxpages * PAGE_SIZE) 1516 len = maxpages * PAGE_SIZE; 1517 addr &= ~(PAGE_SIZE - 1); 1518 n = DIV_ROUND_UP(len, PAGE_SIZE); 1519 res = get_user_pages_fast(addr, n, 1520 iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0, 1521 pages); 1522 if (unlikely(res < 0)) 1523 return res; 1524 return (res == n ? len : res * PAGE_SIZE) - *start; 1525 0;}),({ 1526 /* can't be more than PAGE_SIZE */ 1527 *start = v.bv_offset; 1528 get_page(*pages = v.bv_page); 1529 return v.bv_len; 1530 }),({ 1531 return -EFAULT; 1532 }), 1533 0 1534 ) 1535 return 0; 1536 } 1537 EXPORT_SYMBOL(iov_iter_get_pages); 1538 1539 static struct page **get_pages_array(size_t n) 1540 { 1541 return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL); 1542 } 1543 1544 static ssize_t pipe_get_pages_alloc(struct iov_iter *i, 1545 struct page ***pages, size_t maxsize, 1546 size_t *start) 1547 { 1548 struct page **p; 1549 unsigned int iter_head, npages; 1550 ssize_t n; 1551 1552 if (!maxsize) 1553 return 0; 1554 1555 if (!sanity(i)) 1556 return -EFAULT; 1557 1558 data_start(i, &iter_head, start); 1559 /* Amount of free space: some of this one + all after this one */ 1560 npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe); 1561 n = npages * PAGE_SIZE - *start; 1562 if (maxsize > n) 1563 maxsize = n; 1564 else 1565 npages = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE); 1566 p = get_pages_array(npages); 1567 if (!p) 1568 return -ENOMEM; 1569 n = __pipe_get_pages(i, maxsize, p, iter_head, start); 1570 if (n > 0) 1571 *pages = p; 1572 else 1573 kvfree(p); 1574 return n; 1575 } 1576 1577 static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i, 1578 struct page ***pages, size_t maxsize, 1579 size_t *_start_offset) 1580 { 1581 struct page **p; 1582 unsigned nr, offset; 1583 pgoff_t index, count; 1584 size_t size = maxsize, actual; 1585 loff_t pos; 1586 1587 if (!size) 1588 return 0; 1589 1590 pos = i->xarray_start + i->iov_offset; 1591 index = pos >> PAGE_SHIFT; 1592 offset = pos & ~PAGE_MASK; 1593 *_start_offset = offset; 1594 1595 count = 1; 1596 if (size > PAGE_SIZE - offset) { 1597 size -= PAGE_SIZE - offset; 1598 count += size >> PAGE_SHIFT; 1599 size &= ~PAGE_MASK; 1600 if (size) 1601 count++; 1602 } 1603 1604 p = get_pages_array(count); 1605 if (!p) 1606 return -ENOMEM; 1607 *pages = p; 1608 1609 nr = iter_xarray_populate_pages(p, i->xarray, index, count); 1610 if (nr == 0) 1611 return 0; 1612 1613 actual = PAGE_SIZE * nr; 1614 actual -= offset; 1615 if (nr == count && size > 0) { 1616 unsigned last_offset = (nr > 1) ? 0 : offset; 1617 actual -= PAGE_SIZE - (last_offset + size); 1618 } 1619 return actual; 1620 } 1621 1622 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, 1623 struct page ***pages, size_t maxsize, 1624 size_t *start) 1625 { 1626 struct page **p; 1627 1628 if (maxsize > i->count) 1629 maxsize = i->count; 1630 1631 if (unlikely(iov_iter_is_pipe(i))) 1632 return pipe_get_pages_alloc(i, pages, maxsize, start); 1633 if (unlikely(iov_iter_is_xarray(i))) 1634 return iter_xarray_get_pages_alloc(i, pages, maxsize, start); 1635 if (unlikely(iov_iter_is_discard(i))) 1636 return -EFAULT; 1637 1638 iterate_all_kinds(i, maxsize, v, ({ 1639 unsigned long addr = (unsigned long)v.iov_base; 1640 size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1)); 1641 int n; 1642 int res; 1643 1644 addr &= ~(PAGE_SIZE - 1); 1645 n = DIV_ROUND_UP(len, PAGE_SIZE); 1646 p = get_pages_array(n); 1647 if (!p) 1648 return -ENOMEM; 1649 res = get_user_pages_fast(addr, n, 1650 iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0, p); 1651 if (unlikely(res < 0)) { 1652 kvfree(p); 1653 return res; 1654 } 1655 *pages = p; 1656 return (res == n ? len : res * PAGE_SIZE) - *start; 1657 0;}),({ 1658 /* can't be more than PAGE_SIZE */ 1659 *start = v.bv_offset; 1660 *pages = p = get_pages_array(1); 1661 if (!p) 1662 return -ENOMEM; 1663 get_page(*p = v.bv_page); 1664 return v.bv_len; 1665 }),({ 1666 return -EFAULT; 1667 }), 0 1668 ) 1669 return 0; 1670 } 1671 EXPORT_SYMBOL(iov_iter_get_pages_alloc); 1672 1673 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, 1674 struct iov_iter *i) 1675 { 1676 char *to = addr; 1677 __wsum sum, next; 1678 size_t off = 0; 1679 sum = *csum; 1680 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { 1681 WARN_ON(1); 1682 return 0; 1683 } 1684 iterate_and_advance(i, bytes, v, ({ 1685 next = csum_and_copy_from_user(v.iov_base, 1686 (to += v.iov_len) - v.iov_len, 1687 v.iov_len); 1688 if (next) { 1689 sum = csum_block_add(sum, next, off); 1690 off += v.iov_len; 1691 } 1692 next ? 0 : v.iov_len; 1693 }), ({ 1694 char *p = kmap_atomic(v.bv_page); 1695 sum = csum_and_memcpy((to += v.bv_len) - v.bv_len, 1696 p + v.bv_offset, v.bv_len, 1697 sum, off); 1698 kunmap_atomic(p); 1699 off += v.bv_len; 1700 }),({ 1701 sum = csum_and_memcpy((to += v.iov_len) - v.iov_len, 1702 v.iov_base, v.iov_len, 1703 sum, off); 1704 off += v.iov_len; 1705 }), ({ 1706 char *p = kmap_atomic(v.bv_page); 1707 sum = csum_and_memcpy((to += v.bv_len) - v.bv_len, 1708 p + v.bv_offset, v.bv_len, 1709 sum, off); 1710 kunmap_atomic(p); 1711 off += v.bv_len; 1712 }) 1713 ) 1714 *csum = sum; 1715 return bytes; 1716 } 1717 EXPORT_SYMBOL(csum_and_copy_from_iter); 1718 1719 bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, 1720 struct iov_iter *i) 1721 { 1722 char *to = addr; 1723 __wsum sum, next; 1724 size_t off = 0; 1725 sum = *csum; 1726 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { 1727 WARN_ON(1); 1728 return false; 1729 } 1730 if (unlikely(i->count < bytes)) 1731 return false; 1732 iterate_all_kinds(i, bytes, v, ({ 1733 next = csum_and_copy_from_user(v.iov_base, 1734 (to += v.iov_len) - v.iov_len, 1735 v.iov_len); 1736 if (!next) 1737 return false; 1738 sum = csum_block_add(sum, next, off); 1739 off += v.iov_len; 1740 0; 1741 }), ({ 1742 char *p = kmap_atomic(v.bv_page); 1743 sum = csum_and_memcpy((to += v.bv_len) - v.bv_len, 1744 p + v.bv_offset, v.bv_len, 1745 sum, off); 1746 kunmap_atomic(p); 1747 off += v.bv_len; 1748 }),({ 1749 sum = csum_and_memcpy((to += v.iov_len) - v.iov_len, 1750 v.iov_base, v.iov_len, 1751 sum, off); 1752 off += v.iov_len; 1753 }), ({ 1754 char *p = kmap_atomic(v.bv_page); 1755 sum = csum_and_memcpy((to += v.bv_len) - v.bv_len, 1756 p + v.bv_offset, v.bv_len, 1757 sum, off); 1758 kunmap_atomic(p); 1759 off += v.bv_len; 1760 }) 1761 ) 1762 *csum = sum; 1763 iov_iter_advance(i, bytes); 1764 return true; 1765 } 1766 EXPORT_SYMBOL(csum_and_copy_from_iter_full); 1767 1768 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate, 1769 struct iov_iter *i) 1770 { 1771 struct csum_state *csstate = _csstate; 1772 const char *from = addr; 1773 __wsum sum, next; 1774 size_t off; 1775 1776 if (unlikely(iov_iter_is_pipe(i))) 1777 return csum_and_copy_to_pipe_iter(addr, bytes, _csstate, i); 1778 1779 sum = csstate->csum; 1780 off = csstate->off; 1781 if (unlikely(iov_iter_is_discard(i))) { 1782 WARN_ON(1); /* for now */ 1783 return 0; 1784 } 1785 iterate_and_advance(i, bytes, v, ({ 1786 next = csum_and_copy_to_user((from += v.iov_len) - v.iov_len, 1787 v.iov_base, 1788 v.iov_len); 1789 if (next) { 1790 sum = csum_block_add(sum, next, off); 1791 off += v.iov_len; 1792 } 1793 next ? 0 : v.iov_len; 1794 }), ({ 1795 char *p = kmap_atomic(v.bv_page); 1796 sum = csum_and_memcpy(p + v.bv_offset, 1797 (from += v.bv_len) - v.bv_len, 1798 v.bv_len, sum, off); 1799 kunmap_atomic(p); 1800 off += v.bv_len; 1801 }),({ 1802 sum = csum_and_memcpy(v.iov_base, 1803 (from += v.iov_len) - v.iov_len, 1804 v.iov_len, sum, off); 1805 off += v.iov_len; 1806 }), ({ 1807 char *p = kmap_atomic(v.bv_page); 1808 sum = csum_and_memcpy(p + v.bv_offset, 1809 (from += v.bv_len) - v.bv_len, 1810 v.bv_len, sum, off); 1811 kunmap_atomic(p); 1812 off += v.bv_len; 1813 }) 1814 ) 1815 csstate->csum = sum; 1816 csstate->off = off; 1817 return bytes; 1818 } 1819 EXPORT_SYMBOL(csum_and_copy_to_iter); 1820 1821 size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp, 1822 struct iov_iter *i) 1823 { 1824 #ifdef CONFIG_CRYPTO_HASH 1825 struct ahash_request *hash = hashp; 1826 struct scatterlist sg; 1827 size_t copied; 1828 1829 copied = copy_to_iter(addr, bytes, i); 1830 sg_init_one(&sg, addr, copied); 1831 ahash_request_set_crypt(hash, &sg, NULL, copied); 1832 crypto_ahash_update(hash); 1833 return copied; 1834 #else 1835 return 0; 1836 #endif 1837 } 1838 EXPORT_SYMBOL(hash_and_copy_to_iter); 1839 1840 int iov_iter_npages(const struct iov_iter *i, int maxpages) 1841 { 1842 size_t size = i->count; 1843 int npages = 0; 1844 1845 if (!size) 1846 return 0; 1847 if (unlikely(iov_iter_is_discard(i))) 1848 return 0; 1849 1850 if (unlikely(iov_iter_is_pipe(i))) { 1851 struct pipe_inode_info *pipe = i->pipe; 1852 unsigned int iter_head; 1853 size_t off; 1854 1855 if (!sanity(i)) 1856 return 0; 1857 1858 data_start(i, &iter_head, &off); 1859 /* some of this one + all after this one */ 1860 npages = pipe_space_for_user(iter_head, pipe->tail, pipe); 1861 if (npages >= maxpages) 1862 return maxpages; 1863 } else if (unlikely(iov_iter_is_xarray(i))) { 1864 unsigned offset; 1865 1866 offset = (i->xarray_start + i->iov_offset) & ~PAGE_MASK; 1867 1868 npages = 1; 1869 if (size > PAGE_SIZE - offset) { 1870 size -= PAGE_SIZE - offset; 1871 npages += size >> PAGE_SHIFT; 1872 size &= ~PAGE_MASK; 1873 if (size) 1874 npages++; 1875 } 1876 if (npages >= maxpages) 1877 return maxpages; 1878 } else iterate_all_kinds(i, size, v, ({ 1879 unsigned long p = (unsigned long)v.iov_base; 1880 npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE) 1881 - p / PAGE_SIZE; 1882 if (npages >= maxpages) 1883 return maxpages; 1884 0;}),({ 1885 npages++; 1886 if (npages >= maxpages) 1887 return maxpages; 1888 }),({ 1889 unsigned long p = (unsigned long)v.iov_base; 1890 npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE) 1891 - p / PAGE_SIZE; 1892 if (npages >= maxpages) 1893 return maxpages; 1894 }), 1895 0 1896 ) 1897 return npages; 1898 } 1899 EXPORT_SYMBOL(iov_iter_npages); 1900 1901 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags) 1902 { 1903 *new = *old; 1904 if (unlikely(iov_iter_is_pipe(new))) { 1905 WARN_ON(1); 1906 return NULL; 1907 } 1908 if (unlikely(iov_iter_is_discard(new) || iov_iter_is_xarray(new))) 1909 return NULL; 1910 if (iov_iter_is_bvec(new)) 1911 return new->bvec = kmemdup(new->bvec, 1912 new->nr_segs * sizeof(struct bio_vec), 1913 flags); 1914 else 1915 /* iovec and kvec have identical layout */ 1916 return new->iov = kmemdup(new->iov, 1917 new->nr_segs * sizeof(struct iovec), 1918 flags); 1919 } 1920 EXPORT_SYMBOL(dup_iter); 1921 1922 static int copy_compat_iovec_from_user(struct iovec *iov, 1923 const struct iovec __user *uvec, unsigned long nr_segs) 1924 { 1925 const struct compat_iovec __user *uiov = 1926 (const struct compat_iovec __user *)uvec; 1927 int ret = -EFAULT, i; 1928 1929 if (!user_access_begin(uiov, nr_segs * sizeof(*uiov))) 1930 return -EFAULT; 1931 1932 for (i = 0; i < nr_segs; i++) { 1933 compat_uptr_t buf; 1934 compat_ssize_t len; 1935 1936 unsafe_get_user(len, &uiov[i].iov_len, uaccess_end); 1937 unsafe_get_user(buf, &uiov[i].iov_base, uaccess_end); 1938 1939 /* check for compat_size_t not fitting in compat_ssize_t .. */ 1940 if (len < 0) { 1941 ret = -EINVAL; 1942 goto uaccess_end; 1943 } 1944 iov[i].iov_base = compat_ptr(buf); 1945 iov[i].iov_len = len; 1946 } 1947 1948 ret = 0; 1949 uaccess_end: 1950 user_access_end(); 1951 return ret; 1952 } 1953 1954 static int copy_iovec_from_user(struct iovec *iov, 1955 const struct iovec __user *uvec, unsigned long nr_segs) 1956 { 1957 unsigned long seg; 1958 1959 if (copy_from_user(iov, uvec, nr_segs * sizeof(*uvec))) 1960 return -EFAULT; 1961 for (seg = 0; seg < nr_segs; seg++) { 1962 if ((ssize_t)iov[seg].iov_len < 0) 1963 return -EINVAL; 1964 } 1965 1966 return 0; 1967 } 1968 1969 struct iovec *iovec_from_user(const struct iovec __user *uvec, 1970 unsigned long nr_segs, unsigned long fast_segs, 1971 struct iovec *fast_iov, bool compat) 1972 { 1973 struct iovec *iov = fast_iov; 1974 int ret; 1975 1976 /* 1977 * SuS says "The readv() function *may* fail if the iovcnt argument was 1978 * less than or equal to 0, or greater than {IOV_MAX}. Linux has 1979 * traditionally returned zero for zero segments, so... 1980 */ 1981 if (nr_segs == 0) 1982 return iov; 1983 if (nr_segs > UIO_MAXIOV) 1984 return ERR_PTR(-EINVAL); 1985 if (nr_segs > fast_segs) { 1986 iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL); 1987 if (!iov) 1988 return ERR_PTR(-ENOMEM); 1989 } 1990 1991 if (compat) 1992 ret = copy_compat_iovec_from_user(iov, uvec, nr_segs); 1993 else 1994 ret = copy_iovec_from_user(iov, uvec, nr_segs); 1995 if (ret) { 1996 if (iov != fast_iov) 1997 kfree(iov); 1998 return ERR_PTR(ret); 1999 } 2000 2001 return iov; 2002 } 2003 2004 ssize_t __import_iovec(int type, const struct iovec __user *uvec, 2005 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp, 2006 struct iov_iter *i, bool compat) 2007 { 2008 ssize_t total_len = 0; 2009 unsigned long seg; 2010 struct iovec *iov; 2011 2012 iov = iovec_from_user(uvec, nr_segs, fast_segs, *iovp, compat); 2013 if (IS_ERR(iov)) { 2014 *iovp = NULL; 2015 return PTR_ERR(iov); 2016 } 2017 2018 /* 2019 * According to the Single Unix Specification we should return EINVAL if 2020 * an element length is < 0 when cast to ssize_t or if the total length 2021 * would overflow the ssize_t return value of the system call. 2022 * 2023 * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the 2024 * overflow case. 2025 */ 2026 for (seg = 0; seg < nr_segs; seg++) { 2027 ssize_t len = (ssize_t)iov[seg].iov_len; 2028 2029 if (!access_ok(iov[seg].iov_base, len)) { 2030 if (iov != *iovp) 2031 kfree(iov); 2032 *iovp = NULL; 2033 return -EFAULT; 2034 } 2035 2036 if (len > MAX_RW_COUNT - total_len) { 2037 len = MAX_RW_COUNT - total_len; 2038 iov[seg].iov_len = len; 2039 } 2040 total_len += len; 2041 } 2042 2043 iov_iter_init(i, type, iov, nr_segs, total_len); 2044 if (iov == *iovp) 2045 *iovp = NULL; 2046 else 2047 *iovp = iov; 2048 return total_len; 2049 } 2050 2051 /** 2052 * import_iovec() - Copy an array of &struct iovec from userspace 2053 * into the kernel, check that it is valid, and initialize a new 2054 * &struct iov_iter iterator to access it. 2055 * 2056 * @type: One of %READ or %WRITE. 2057 * @uvec: Pointer to the userspace array. 2058 * @nr_segs: Number of elements in userspace array. 2059 * @fast_segs: Number of elements in @iov. 2060 * @iovp: (input and output parameter) Pointer to pointer to (usually small 2061 * on-stack) kernel array. 2062 * @i: Pointer to iterator that will be initialized on success. 2063 * 2064 * If the array pointed to by *@iov is large enough to hold all @nr_segs, 2065 * then this function places %NULL in *@iov on return. Otherwise, a new 2066 * array will be allocated and the result placed in *@iov. This means that 2067 * the caller may call kfree() on *@iov regardless of whether the small 2068 * on-stack array was used or not (and regardless of whether this function 2069 * returns an error or not). 2070 * 2071 * Return: Negative error code on error, bytes imported on success 2072 */ 2073 ssize_t import_iovec(int type, const struct iovec __user *uvec, 2074 unsigned nr_segs, unsigned fast_segs, 2075 struct iovec **iovp, struct iov_iter *i) 2076 { 2077 return __import_iovec(type, uvec, nr_segs, fast_segs, iovp, i, 2078 in_compat_syscall()); 2079 } 2080 EXPORT_SYMBOL(import_iovec); 2081 2082 int import_single_range(int rw, void __user *buf, size_t len, 2083 struct iovec *iov, struct iov_iter *i) 2084 { 2085 if (len > MAX_RW_COUNT) 2086 len = MAX_RW_COUNT; 2087 if (unlikely(!access_ok(buf, len))) 2088 return -EFAULT; 2089 2090 iov->iov_base = buf; 2091 iov->iov_len = len; 2092 iov_iter_init(i, rw, iov, 1, len); 2093 return 0; 2094 } 2095 EXPORT_SYMBOL(import_single_range); 2096 2097 int iov_iter_for_each_range(struct iov_iter *i, size_t bytes, 2098 int (*f)(struct kvec *vec, void *context), 2099 void *context) 2100 { 2101 struct kvec w; 2102 int err = -EINVAL; 2103 if (!bytes) 2104 return 0; 2105 2106 iterate_all_kinds(i, bytes, v, -EINVAL, ({ 2107 w.iov_base = kmap(v.bv_page) + v.bv_offset; 2108 w.iov_len = v.bv_len; 2109 err = f(&w, context); 2110 kunmap(v.bv_page); 2111 err;}), ({ 2112 w = v; 2113 err = f(&w, context);}), ({ 2114 w.iov_base = kmap(v.bv_page) + v.bv_offset; 2115 w.iov_len = v.bv_len; 2116 err = f(&w, context); 2117 kunmap(v.bv_page); 2118 err;}) 2119 ) 2120 return err; 2121 } 2122 EXPORT_SYMBOL(iov_iter_for_each_range); 2123