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