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_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_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 buf->flags = 0; 420 get_page(page); 421 buf->page = page; 422 buf->offset = offset; 423 buf->len = bytes; 424 425 pipe->head = i_head + 1; 426 i->iov_offset = offset + bytes; 427 i->head = i_head; 428 out: 429 i->count -= bytes; 430 return bytes; 431 } 432 433 /* 434 * fault_in_iov_iter_readable - fault in iov iterator for reading 435 * @i: iterator 436 * @size: maximum length 437 * 438 * Fault in one or more iovecs of the given iov_iter, to a maximum length of 439 * @size. For each iovec, fault in each page that constitutes the iovec. 440 * 441 * Returns the number of bytes not faulted in (like copy_to_user() and 442 * copy_from_user()). 443 * 444 * Always returns 0 for non-userspace iterators. 445 */ 446 size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t size) 447 { 448 if (iter_is_iovec(i)) { 449 size_t count = min(size, iov_iter_count(i)); 450 const struct iovec *p; 451 size_t skip; 452 453 size -= count; 454 for (p = i->iov, skip = i->iov_offset; count; p++, skip = 0) { 455 size_t len = min(count, p->iov_len - skip); 456 size_t ret; 457 458 if (unlikely(!len)) 459 continue; 460 ret = fault_in_readable(p->iov_base + skip, len); 461 count -= len - ret; 462 if (ret) 463 break; 464 } 465 return count + size; 466 } 467 return 0; 468 } 469 EXPORT_SYMBOL(fault_in_iov_iter_readable); 470 471 /* 472 * fault_in_iov_iter_writeable - fault in iov iterator for writing 473 * @i: iterator 474 * @size: maximum length 475 * 476 * Faults in the iterator using get_user_pages(), i.e., without triggering 477 * hardware page faults. This is primarily useful when we already know that 478 * some or all of the pages in @i aren't in memory. 479 * 480 * Returns the number of bytes not faulted in, like copy_to_user() and 481 * copy_from_user(). 482 * 483 * Always returns 0 for non-user-space iterators. 484 */ 485 size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t size) 486 { 487 if (iter_is_iovec(i)) { 488 size_t count = min(size, iov_iter_count(i)); 489 const struct iovec *p; 490 size_t skip; 491 492 size -= count; 493 for (p = i->iov, skip = i->iov_offset; count; p++, skip = 0) { 494 size_t len = min(count, p->iov_len - skip); 495 size_t ret; 496 497 if (unlikely(!len)) 498 continue; 499 ret = fault_in_safe_writeable(p->iov_base + skip, len); 500 count -= len - ret; 501 if (ret) 502 break; 503 } 504 return count + size; 505 } 506 return 0; 507 } 508 EXPORT_SYMBOL(fault_in_iov_iter_writeable); 509 510 void iov_iter_init(struct iov_iter *i, unsigned int direction, 511 const struct iovec *iov, unsigned long nr_segs, 512 size_t count) 513 { 514 WARN_ON(direction & ~(READ | WRITE)); 515 *i = (struct iov_iter) { 516 .iter_type = ITER_IOVEC, 517 .nofault = false, 518 .data_source = direction, 519 .iov = iov, 520 .nr_segs = nr_segs, 521 .iov_offset = 0, 522 .count = count 523 }; 524 } 525 EXPORT_SYMBOL(iov_iter_init); 526 527 static inline bool allocated(struct pipe_buffer *buf) 528 { 529 return buf->ops == &default_pipe_buf_ops; 530 } 531 532 static inline void data_start(const struct iov_iter *i, 533 unsigned int *iter_headp, size_t *offp) 534 { 535 unsigned int p_mask = i->pipe->ring_size - 1; 536 unsigned int iter_head = i->head; 537 size_t off = i->iov_offset; 538 539 if (off && (!allocated(&i->pipe->bufs[iter_head & p_mask]) || 540 off == PAGE_SIZE)) { 541 iter_head++; 542 off = 0; 543 } 544 *iter_headp = iter_head; 545 *offp = off; 546 } 547 548 static size_t push_pipe(struct iov_iter *i, size_t size, 549 int *iter_headp, size_t *offp) 550 { 551 struct pipe_inode_info *pipe = i->pipe; 552 unsigned int p_tail = pipe->tail; 553 unsigned int p_mask = pipe->ring_size - 1; 554 unsigned int iter_head; 555 size_t off; 556 ssize_t left; 557 558 if (unlikely(size > i->count)) 559 size = i->count; 560 if (unlikely(!size)) 561 return 0; 562 563 left = size; 564 data_start(i, &iter_head, &off); 565 *iter_headp = iter_head; 566 *offp = off; 567 if (off) { 568 left -= PAGE_SIZE - off; 569 if (left <= 0) { 570 pipe->bufs[iter_head & p_mask].len += size; 571 return size; 572 } 573 pipe->bufs[iter_head & p_mask].len = PAGE_SIZE; 574 iter_head++; 575 } 576 while (!pipe_full(iter_head, p_tail, pipe->max_usage)) { 577 struct pipe_buffer *buf = &pipe->bufs[iter_head & p_mask]; 578 struct page *page = alloc_page(GFP_USER); 579 if (!page) 580 break; 581 582 buf->ops = &default_pipe_buf_ops; 583 buf->flags = 0; 584 buf->page = page; 585 buf->offset = 0; 586 buf->len = min_t(ssize_t, left, PAGE_SIZE); 587 left -= buf->len; 588 iter_head++; 589 pipe->head = iter_head; 590 591 if (left == 0) 592 return size; 593 } 594 return size - left; 595 } 596 597 static size_t copy_pipe_to_iter(const void *addr, size_t bytes, 598 struct iov_iter *i) 599 { 600 struct pipe_inode_info *pipe = i->pipe; 601 unsigned int p_mask = pipe->ring_size - 1; 602 unsigned int i_head; 603 size_t n, off; 604 605 if (!sanity(i)) 606 return 0; 607 608 bytes = n = push_pipe(i, bytes, &i_head, &off); 609 if (unlikely(!n)) 610 return 0; 611 do { 612 size_t chunk = min_t(size_t, n, PAGE_SIZE - off); 613 memcpy_to_page(pipe->bufs[i_head & p_mask].page, off, addr, chunk); 614 i->head = i_head; 615 i->iov_offset = off + chunk; 616 n -= chunk; 617 addr += chunk; 618 off = 0; 619 i_head++; 620 } while (n); 621 i->count -= bytes; 622 return bytes; 623 } 624 625 static __wsum csum_and_memcpy(void *to, const void *from, size_t len, 626 __wsum sum, size_t off) 627 { 628 __wsum next = csum_partial_copy_nocheck(from, to, len); 629 return csum_block_add(sum, next, off); 630 } 631 632 static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes, 633 struct iov_iter *i, __wsum *sump) 634 { 635 struct pipe_inode_info *pipe = i->pipe; 636 unsigned int p_mask = pipe->ring_size - 1; 637 __wsum sum = *sump; 638 size_t off = 0; 639 unsigned int i_head; 640 size_t r; 641 642 if (!sanity(i)) 643 return 0; 644 645 bytes = push_pipe(i, bytes, &i_head, &r); 646 while (bytes) { 647 size_t chunk = min_t(size_t, bytes, PAGE_SIZE - r); 648 char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page); 649 sum = csum_and_memcpy(p + r, addr + off, chunk, sum, off); 650 kunmap_local(p); 651 i->head = i_head; 652 i->iov_offset = r + chunk; 653 bytes -= chunk; 654 off += chunk; 655 r = 0; 656 i_head++; 657 } 658 *sump = sum; 659 i->count -= off; 660 return off; 661 } 662 663 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i) 664 { 665 if (unlikely(iov_iter_is_pipe(i))) 666 return copy_pipe_to_iter(addr, bytes, i); 667 if (iter_is_iovec(i)) 668 might_fault(); 669 iterate_and_advance(i, bytes, base, len, off, 670 copyout(base, addr + off, len), 671 memcpy(base, addr + off, len) 672 ) 673 674 return bytes; 675 } 676 EXPORT_SYMBOL(_copy_to_iter); 677 678 #ifdef CONFIG_ARCH_HAS_COPY_MC 679 static int copyout_mc(void __user *to, const void *from, size_t n) 680 { 681 if (access_ok(to, n)) { 682 instrument_copy_to_user(to, from, n); 683 n = copy_mc_to_user((__force void *) to, from, n); 684 } 685 return n; 686 } 687 688 static size_t copy_mc_pipe_to_iter(const void *addr, size_t bytes, 689 struct iov_iter *i) 690 { 691 struct pipe_inode_info *pipe = i->pipe; 692 unsigned int p_mask = pipe->ring_size - 1; 693 unsigned int i_head; 694 size_t n, off, xfer = 0; 695 696 if (!sanity(i)) 697 return 0; 698 699 n = push_pipe(i, bytes, &i_head, &off); 700 while (n) { 701 size_t chunk = min_t(size_t, n, PAGE_SIZE - off); 702 char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page); 703 unsigned long rem; 704 rem = copy_mc_to_kernel(p + off, addr + xfer, chunk); 705 chunk -= rem; 706 kunmap_local(p); 707 i->head = i_head; 708 i->iov_offset = off + chunk; 709 xfer += chunk; 710 if (rem) 711 break; 712 n -= chunk; 713 off = 0; 714 i_head++; 715 } 716 i->count -= xfer; 717 return xfer; 718 } 719 720 /** 721 * _copy_mc_to_iter - copy to iter with source memory error exception handling 722 * @addr: source kernel address 723 * @bytes: total transfer length 724 * @i: destination iterator 725 * 726 * The pmem driver deploys this for the dax operation 727 * (dax_copy_to_iter()) for dax reads (bypass page-cache and the 728 * block-layer). Upon #MC read(2) aborts and returns EIO or the bytes 729 * successfully copied. 730 * 731 * The main differences between this and typical _copy_to_iter(). 732 * 733 * * Typical tail/residue handling after a fault retries the copy 734 * byte-by-byte until the fault happens again. Re-triggering machine 735 * checks is potentially fatal so the implementation uses source 736 * alignment and poison alignment assumptions to avoid re-triggering 737 * hardware exceptions. 738 * 739 * * ITER_KVEC, ITER_PIPE, and ITER_BVEC can return short copies. 740 * Compare to copy_to_iter() where only ITER_IOVEC attempts might return 741 * a short copy. 742 * 743 * Return: number of bytes copied (may be %0) 744 */ 745 size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i) 746 { 747 if (unlikely(iov_iter_is_pipe(i))) 748 return copy_mc_pipe_to_iter(addr, bytes, i); 749 if (iter_is_iovec(i)) 750 might_fault(); 751 __iterate_and_advance(i, bytes, base, len, off, 752 copyout_mc(base, addr + off, len), 753 copy_mc_to_kernel(base, addr + off, len) 754 ) 755 756 return bytes; 757 } 758 EXPORT_SYMBOL_GPL(_copy_mc_to_iter); 759 #endif /* CONFIG_ARCH_HAS_COPY_MC */ 760 761 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) 762 { 763 if (unlikely(iov_iter_is_pipe(i))) { 764 WARN_ON(1); 765 return 0; 766 } 767 if (iter_is_iovec(i)) 768 might_fault(); 769 iterate_and_advance(i, bytes, base, len, off, 770 copyin(addr + off, base, len), 771 memcpy(addr + off, base, len) 772 ) 773 774 return bytes; 775 } 776 EXPORT_SYMBOL(_copy_from_iter); 777 778 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i) 779 { 780 if (unlikely(iov_iter_is_pipe(i))) { 781 WARN_ON(1); 782 return 0; 783 } 784 iterate_and_advance(i, bytes, base, len, off, 785 __copy_from_user_inatomic_nocache(addr + off, base, len), 786 memcpy(addr + off, base, len) 787 ) 788 789 return bytes; 790 } 791 EXPORT_SYMBOL(_copy_from_iter_nocache); 792 793 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE 794 /** 795 * _copy_from_iter_flushcache - write destination through cpu cache 796 * @addr: destination kernel address 797 * @bytes: total transfer length 798 * @i: source iterator 799 * 800 * The pmem driver arranges for filesystem-dax to use this facility via 801 * dax_copy_from_iter() for ensuring that writes to persistent memory 802 * are flushed through the CPU cache. It is differentiated from 803 * _copy_from_iter_nocache() in that guarantees all data is flushed for 804 * all iterator types. The _copy_from_iter_nocache() only attempts to 805 * bypass the cache for the ITER_IOVEC case, and on some archs may use 806 * instructions that strand dirty-data in the cache. 807 * 808 * Return: number of bytes copied (may be %0) 809 */ 810 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i) 811 { 812 if (unlikely(iov_iter_is_pipe(i))) { 813 WARN_ON(1); 814 return 0; 815 } 816 iterate_and_advance(i, bytes, base, len, off, 817 __copy_from_user_flushcache(addr + off, base, len), 818 memcpy_flushcache(addr + off, base, len) 819 ) 820 821 return bytes; 822 } 823 EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache); 824 #endif 825 826 static inline bool page_copy_sane(struct page *page, size_t offset, size_t n) 827 { 828 struct page *head; 829 size_t v = n + offset; 830 831 /* 832 * The general case needs to access the page order in order 833 * to compute the page size. 834 * However, we mostly deal with order-0 pages and thus can 835 * avoid a possible cache line miss for requests that fit all 836 * page orders. 837 */ 838 if (n <= v && v <= PAGE_SIZE) 839 return true; 840 841 head = compound_head(page); 842 v += (page - head) << PAGE_SHIFT; 843 844 if (likely(n <= v && v <= (page_size(head)))) 845 return true; 846 WARN_ON(1); 847 return false; 848 } 849 850 static size_t __copy_page_to_iter(struct page *page, size_t offset, size_t bytes, 851 struct iov_iter *i) 852 { 853 if (likely(iter_is_iovec(i))) 854 return copy_page_to_iter_iovec(page, offset, bytes, i); 855 if (iov_iter_is_bvec(i) || iov_iter_is_kvec(i) || iov_iter_is_xarray(i)) { 856 void *kaddr = kmap_local_page(page); 857 size_t wanted = _copy_to_iter(kaddr + offset, bytes, i); 858 kunmap_local(kaddr); 859 return wanted; 860 } 861 if (iov_iter_is_pipe(i)) 862 return copy_page_to_iter_pipe(page, offset, bytes, i); 863 if (unlikely(iov_iter_is_discard(i))) { 864 if (unlikely(i->count < bytes)) 865 bytes = i->count; 866 i->count -= bytes; 867 return bytes; 868 } 869 WARN_ON(1); 870 return 0; 871 } 872 873 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, 874 struct iov_iter *i) 875 { 876 size_t res = 0; 877 if (unlikely(!page_copy_sane(page, offset, bytes))) 878 return 0; 879 page += offset / PAGE_SIZE; // first subpage 880 offset %= PAGE_SIZE; 881 while (1) { 882 size_t n = __copy_page_to_iter(page, offset, 883 min(bytes, (size_t)PAGE_SIZE - offset), i); 884 res += n; 885 bytes -= n; 886 if (!bytes || !n) 887 break; 888 offset += n; 889 if (offset == PAGE_SIZE) { 890 page++; 891 offset = 0; 892 } 893 } 894 return res; 895 } 896 EXPORT_SYMBOL(copy_page_to_iter); 897 898 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, 899 struct iov_iter *i) 900 { 901 if (unlikely(!page_copy_sane(page, offset, bytes))) 902 return 0; 903 if (likely(iter_is_iovec(i))) 904 return copy_page_from_iter_iovec(page, offset, bytes, i); 905 if (iov_iter_is_bvec(i) || iov_iter_is_kvec(i) || iov_iter_is_xarray(i)) { 906 void *kaddr = kmap_local_page(page); 907 size_t wanted = _copy_from_iter(kaddr + offset, bytes, i); 908 kunmap_local(kaddr); 909 return wanted; 910 } 911 WARN_ON(1); 912 return 0; 913 } 914 EXPORT_SYMBOL(copy_page_from_iter); 915 916 static size_t pipe_zero(size_t bytes, struct iov_iter *i) 917 { 918 struct pipe_inode_info *pipe = i->pipe; 919 unsigned int p_mask = pipe->ring_size - 1; 920 unsigned int i_head; 921 size_t n, off; 922 923 if (!sanity(i)) 924 return 0; 925 926 bytes = n = push_pipe(i, bytes, &i_head, &off); 927 if (unlikely(!n)) 928 return 0; 929 930 do { 931 size_t chunk = min_t(size_t, n, PAGE_SIZE - off); 932 char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page); 933 memset(p + off, 0, chunk); 934 kunmap_local(p); 935 i->head = i_head; 936 i->iov_offset = off + chunk; 937 n -= chunk; 938 off = 0; 939 i_head++; 940 } while (n); 941 i->count -= bytes; 942 return bytes; 943 } 944 945 size_t iov_iter_zero(size_t bytes, struct iov_iter *i) 946 { 947 if (unlikely(iov_iter_is_pipe(i))) 948 return pipe_zero(bytes, i); 949 iterate_and_advance(i, bytes, base, len, count, 950 clear_user(base, len), 951 memset(base, 0, len) 952 ) 953 954 return bytes; 955 } 956 EXPORT_SYMBOL(iov_iter_zero); 957 958 size_t copy_page_from_iter_atomic(struct page *page, unsigned offset, size_t bytes, 959 struct iov_iter *i) 960 { 961 char *kaddr = kmap_atomic(page), *p = kaddr + offset; 962 if (unlikely(!page_copy_sane(page, offset, bytes))) { 963 kunmap_atomic(kaddr); 964 return 0; 965 } 966 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { 967 kunmap_atomic(kaddr); 968 WARN_ON(1); 969 return 0; 970 } 971 iterate_and_advance(i, bytes, base, len, off, 972 copyin(p + off, base, len), 973 memcpy(p + off, base, len) 974 ) 975 kunmap_atomic(kaddr); 976 return bytes; 977 } 978 EXPORT_SYMBOL(copy_page_from_iter_atomic); 979 980 static inline void pipe_truncate(struct iov_iter *i) 981 { 982 struct pipe_inode_info *pipe = i->pipe; 983 unsigned int p_tail = pipe->tail; 984 unsigned int p_head = pipe->head; 985 unsigned int p_mask = pipe->ring_size - 1; 986 987 if (!pipe_empty(p_head, p_tail)) { 988 struct pipe_buffer *buf; 989 unsigned int i_head = i->head; 990 size_t off = i->iov_offset; 991 992 if (off) { 993 buf = &pipe->bufs[i_head & p_mask]; 994 buf->len = off - buf->offset; 995 i_head++; 996 } 997 while (p_head != i_head) { 998 p_head--; 999 pipe_buf_release(pipe, &pipe->bufs[p_head & p_mask]); 1000 } 1001 1002 pipe->head = p_head; 1003 } 1004 } 1005 1006 static void pipe_advance(struct iov_iter *i, size_t size) 1007 { 1008 struct pipe_inode_info *pipe = i->pipe; 1009 if (size) { 1010 struct pipe_buffer *buf; 1011 unsigned int p_mask = pipe->ring_size - 1; 1012 unsigned int i_head = i->head; 1013 size_t off = i->iov_offset, left = size; 1014 1015 if (off) /* make it relative to the beginning of buffer */ 1016 left += off - pipe->bufs[i_head & p_mask].offset; 1017 while (1) { 1018 buf = &pipe->bufs[i_head & p_mask]; 1019 if (left <= buf->len) 1020 break; 1021 left -= buf->len; 1022 i_head++; 1023 } 1024 i->head = i_head; 1025 i->iov_offset = buf->offset + left; 1026 } 1027 i->count -= size; 1028 /* ... and discard everything past that point */ 1029 pipe_truncate(i); 1030 } 1031 1032 static void iov_iter_bvec_advance(struct iov_iter *i, size_t size) 1033 { 1034 struct bvec_iter bi; 1035 1036 bi.bi_size = i->count; 1037 bi.bi_bvec_done = i->iov_offset; 1038 bi.bi_idx = 0; 1039 bvec_iter_advance(i->bvec, &bi, size); 1040 1041 i->bvec += bi.bi_idx; 1042 i->nr_segs -= bi.bi_idx; 1043 i->count = bi.bi_size; 1044 i->iov_offset = bi.bi_bvec_done; 1045 } 1046 1047 static void iov_iter_iovec_advance(struct iov_iter *i, size_t size) 1048 { 1049 const struct iovec *iov, *end; 1050 1051 if (!i->count) 1052 return; 1053 i->count -= size; 1054 1055 size += i->iov_offset; // from beginning of current segment 1056 for (iov = i->iov, end = iov + i->nr_segs; iov < end; iov++) { 1057 if (likely(size < iov->iov_len)) 1058 break; 1059 size -= iov->iov_len; 1060 } 1061 i->iov_offset = size; 1062 i->nr_segs -= iov - i->iov; 1063 i->iov = iov; 1064 } 1065 1066 void iov_iter_advance(struct iov_iter *i, size_t size) 1067 { 1068 if (unlikely(i->count < size)) 1069 size = i->count; 1070 if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) { 1071 /* iovec and kvec have identical layouts */ 1072 iov_iter_iovec_advance(i, size); 1073 } else if (iov_iter_is_bvec(i)) { 1074 iov_iter_bvec_advance(i, size); 1075 } else if (iov_iter_is_pipe(i)) { 1076 pipe_advance(i, size); 1077 } else if (unlikely(iov_iter_is_xarray(i))) { 1078 i->iov_offset += size; 1079 i->count -= size; 1080 } else if (iov_iter_is_discard(i)) { 1081 i->count -= size; 1082 } 1083 } 1084 EXPORT_SYMBOL(iov_iter_advance); 1085 1086 void iov_iter_revert(struct iov_iter *i, size_t unroll) 1087 { 1088 if (!unroll) 1089 return; 1090 if (WARN_ON(unroll > MAX_RW_COUNT)) 1091 return; 1092 i->count += unroll; 1093 if (unlikely(iov_iter_is_pipe(i))) { 1094 struct pipe_inode_info *pipe = i->pipe; 1095 unsigned int p_mask = pipe->ring_size - 1; 1096 unsigned int i_head = i->head; 1097 size_t off = i->iov_offset; 1098 while (1) { 1099 struct pipe_buffer *b = &pipe->bufs[i_head & p_mask]; 1100 size_t n = off - b->offset; 1101 if (unroll < n) { 1102 off -= unroll; 1103 break; 1104 } 1105 unroll -= n; 1106 if (!unroll && i_head == i->start_head) { 1107 off = 0; 1108 break; 1109 } 1110 i_head--; 1111 b = &pipe->bufs[i_head & p_mask]; 1112 off = b->offset + b->len; 1113 } 1114 i->iov_offset = off; 1115 i->head = i_head; 1116 pipe_truncate(i); 1117 return; 1118 } 1119 if (unlikely(iov_iter_is_discard(i))) 1120 return; 1121 if (unroll <= i->iov_offset) { 1122 i->iov_offset -= unroll; 1123 return; 1124 } 1125 unroll -= i->iov_offset; 1126 if (iov_iter_is_xarray(i)) { 1127 BUG(); /* We should never go beyond the start of the specified 1128 * range since we might then be straying into pages that 1129 * aren't pinned. 1130 */ 1131 } else if (iov_iter_is_bvec(i)) { 1132 const struct bio_vec *bvec = i->bvec; 1133 while (1) { 1134 size_t n = (--bvec)->bv_len; 1135 i->nr_segs++; 1136 if (unroll <= n) { 1137 i->bvec = bvec; 1138 i->iov_offset = n - unroll; 1139 return; 1140 } 1141 unroll -= n; 1142 } 1143 } else { /* same logics for iovec and kvec */ 1144 const struct iovec *iov = i->iov; 1145 while (1) { 1146 size_t n = (--iov)->iov_len; 1147 i->nr_segs++; 1148 if (unroll <= n) { 1149 i->iov = iov; 1150 i->iov_offset = n - unroll; 1151 return; 1152 } 1153 unroll -= n; 1154 } 1155 } 1156 } 1157 EXPORT_SYMBOL(iov_iter_revert); 1158 1159 /* 1160 * Return the count of just the current iov_iter segment. 1161 */ 1162 size_t iov_iter_single_seg_count(const struct iov_iter *i) 1163 { 1164 if (i->nr_segs > 1) { 1165 if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) 1166 return min(i->count, i->iov->iov_len - i->iov_offset); 1167 if (iov_iter_is_bvec(i)) 1168 return min(i->count, i->bvec->bv_len - i->iov_offset); 1169 } 1170 return i->count; 1171 } 1172 EXPORT_SYMBOL(iov_iter_single_seg_count); 1173 1174 void iov_iter_kvec(struct iov_iter *i, unsigned int direction, 1175 const struct kvec *kvec, unsigned long nr_segs, 1176 size_t count) 1177 { 1178 WARN_ON(direction & ~(READ | WRITE)); 1179 *i = (struct iov_iter){ 1180 .iter_type = ITER_KVEC, 1181 .data_source = direction, 1182 .kvec = kvec, 1183 .nr_segs = nr_segs, 1184 .iov_offset = 0, 1185 .count = count 1186 }; 1187 } 1188 EXPORT_SYMBOL(iov_iter_kvec); 1189 1190 void iov_iter_bvec(struct iov_iter *i, unsigned int direction, 1191 const struct bio_vec *bvec, unsigned long nr_segs, 1192 size_t count) 1193 { 1194 WARN_ON(direction & ~(READ | WRITE)); 1195 *i = (struct iov_iter){ 1196 .iter_type = ITER_BVEC, 1197 .data_source = direction, 1198 .bvec = bvec, 1199 .nr_segs = nr_segs, 1200 .iov_offset = 0, 1201 .count = count 1202 }; 1203 } 1204 EXPORT_SYMBOL(iov_iter_bvec); 1205 1206 void iov_iter_pipe(struct iov_iter *i, unsigned int direction, 1207 struct pipe_inode_info *pipe, 1208 size_t count) 1209 { 1210 BUG_ON(direction != READ); 1211 WARN_ON(pipe_full(pipe->head, pipe->tail, pipe->ring_size)); 1212 *i = (struct iov_iter){ 1213 .iter_type = ITER_PIPE, 1214 .data_source = false, 1215 .pipe = pipe, 1216 .head = pipe->head, 1217 .start_head = pipe->head, 1218 .iov_offset = 0, 1219 .count = count 1220 }; 1221 } 1222 EXPORT_SYMBOL(iov_iter_pipe); 1223 1224 /** 1225 * iov_iter_xarray - Initialise an I/O iterator to use the pages in an xarray 1226 * @i: The iterator to initialise. 1227 * @direction: The direction of the transfer. 1228 * @xarray: The xarray to access. 1229 * @start: The start file position. 1230 * @count: The size of the I/O buffer in bytes. 1231 * 1232 * Set up an I/O iterator to either draw data out of the pages attached to an 1233 * inode or to inject data into those pages. The pages *must* be prevented 1234 * from evaporation, either by taking a ref on them or locking them by the 1235 * caller. 1236 */ 1237 void iov_iter_xarray(struct iov_iter *i, unsigned int direction, 1238 struct xarray *xarray, loff_t start, size_t count) 1239 { 1240 BUG_ON(direction & ~1); 1241 *i = (struct iov_iter) { 1242 .iter_type = ITER_XARRAY, 1243 .data_source = direction, 1244 .xarray = xarray, 1245 .xarray_start = start, 1246 .count = count, 1247 .iov_offset = 0 1248 }; 1249 } 1250 EXPORT_SYMBOL(iov_iter_xarray); 1251 1252 /** 1253 * iov_iter_discard - Initialise an I/O iterator that discards data 1254 * @i: The iterator to initialise. 1255 * @direction: The direction of the transfer. 1256 * @count: The size of the I/O buffer in bytes. 1257 * 1258 * Set up an I/O iterator that just discards everything that's written to it. 1259 * It's only available as a READ iterator. 1260 */ 1261 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count) 1262 { 1263 BUG_ON(direction != READ); 1264 *i = (struct iov_iter){ 1265 .iter_type = ITER_DISCARD, 1266 .data_source = false, 1267 .count = count, 1268 .iov_offset = 0 1269 }; 1270 } 1271 EXPORT_SYMBOL(iov_iter_discard); 1272 1273 static unsigned long iov_iter_alignment_iovec(const struct iov_iter *i) 1274 { 1275 unsigned long res = 0; 1276 size_t size = i->count; 1277 size_t skip = i->iov_offset; 1278 unsigned k; 1279 1280 for (k = 0; k < i->nr_segs; k++, skip = 0) { 1281 size_t len = i->iov[k].iov_len - skip; 1282 if (len) { 1283 res |= (unsigned long)i->iov[k].iov_base + skip; 1284 if (len > size) 1285 len = size; 1286 res |= len; 1287 size -= len; 1288 if (!size) 1289 break; 1290 } 1291 } 1292 return res; 1293 } 1294 1295 static unsigned long iov_iter_alignment_bvec(const struct iov_iter *i) 1296 { 1297 unsigned res = 0; 1298 size_t size = i->count; 1299 unsigned skip = i->iov_offset; 1300 unsigned k; 1301 1302 for (k = 0; k < i->nr_segs; k++, skip = 0) { 1303 size_t len = i->bvec[k].bv_len - skip; 1304 res |= (unsigned long)i->bvec[k].bv_offset + skip; 1305 if (len > size) 1306 len = size; 1307 res |= len; 1308 size -= len; 1309 if (!size) 1310 break; 1311 } 1312 return res; 1313 } 1314 1315 unsigned long iov_iter_alignment(const struct iov_iter *i) 1316 { 1317 /* iovec and kvec have identical layouts */ 1318 if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) 1319 return iov_iter_alignment_iovec(i); 1320 1321 if (iov_iter_is_bvec(i)) 1322 return iov_iter_alignment_bvec(i); 1323 1324 if (iov_iter_is_pipe(i)) { 1325 unsigned int p_mask = i->pipe->ring_size - 1; 1326 size_t size = i->count; 1327 1328 if (size && i->iov_offset && allocated(&i->pipe->bufs[i->head & p_mask])) 1329 return size | i->iov_offset; 1330 return size; 1331 } 1332 1333 if (iov_iter_is_xarray(i)) 1334 return (i->xarray_start + i->iov_offset) | i->count; 1335 1336 return 0; 1337 } 1338 EXPORT_SYMBOL(iov_iter_alignment); 1339 1340 unsigned long iov_iter_gap_alignment(const struct iov_iter *i) 1341 { 1342 unsigned long res = 0; 1343 unsigned long v = 0; 1344 size_t size = i->count; 1345 unsigned k; 1346 1347 if (WARN_ON(!iter_is_iovec(i))) 1348 return ~0U; 1349 1350 for (k = 0; k < i->nr_segs; k++) { 1351 if (i->iov[k].iov_len) { 1352 unsigned long base = (unsigned long)i->iov[k].iov_base; 1353 if (v) // if not the first one 1354 res |= base | v; // this start | previous end 1355 v = base + i->iov[k].iov_len; 1356 if (size <= i->iov[k].iov_len) 1357 break; 1358 size -= i->iov[k].iov_len; 1359 } 1360 } 1361 return res; 1362 } 1363 EXPORT_SYMBOL(iov_iter_gap_alignment); 1364 1365 static inline ssize_t __pipe_get_pages(struct iov_iter *i, 1366 size_t maxsize, 1367 struct page **pages, 1368 int iter_head, 1369 size_t *start) 1370 { 1371 struct pipe_inode_info *pipe = i->pipe; 1372 unsigned int p_mask = pipe->ring_size - 1; 1373 ssize_t n = push_pipe(i, maxsize, &iter_head, start); 1374 if (!n) 1375 return -EFAULT; 1376 1377 maxsize = n; 1378 n += *start; 1379 while (n > 0) { 1380 get_page(*pages++ = pipe->bufs[iter_head & p_mask].page); 1381 iter_head++; 1382 n -= PAGE_SIZE; 1383 } 1384 1385 return maxsize; 1386 } 1387 1388 static ssize_t pipe_get_pages(struct iov_iter *i, 1389 struct page **pages, size_t maxsize, unsigned maxpages, 1390 size_t *start) 1391 { 1392 unsigned int iter_head, npages; 1393 size_t capacity; 1394 1395 if (!sanity(i)) 1396 return -EFAULT; 1397 1398 data_start(i, &iter_head, start); 1399 /* Amount of free space: some of this one + all after this one */ 1400 npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe); 1401 capacity = min(npages, maxpages) * PAGE_SIZE - *start; 1402 1403 return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start); 1404 } 1405 1406 static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa, 1407 pgoff_t index, unsigned int nr_pages) 1408 { 1409 XA_STATE(xas, xa, index); 1410 struct page *page; 1411 unsigned int ret = 0; 1412 1413 rcu_read_lock(); 1414 for (page = xas_load(&xas); page; page = xas_next(&xas)) { 1415 if (xas_retry(&xas, page)) 1416 continue; 1417 1418 /* Has the page moved or been split? */ 1419 if (unlikely(page != xas_reload(&xas))) { 1420 xas_reset(&xas); 1421 continue; 1422 } 1423 1424 pages[ret] = find_subpage(page, xas.xa_index); 1425 get_page(pages[ret]); 1426 if (++ret == nr_pages) 1427 break; 1428 } 1429 rcu_read_unlock(); 1430 return ret; 1431 } 1432 1433 static ssize_t iter_xarray_get_pages(struct iov_iter *i, 1434 struct page **pages, size_t maxsize, 1435 unsigned maxpages, size_t *_start_offset) 1436 { 1437 unsigned nr, offset; 1438 pgoff_t index, count; 1439 size_t size = maxsize; 1440 loff_t pos; 1441 1442 if (!size || !maxpages) 1443 return 0; 1444 1445 pos = i->xarray_start + i->iov_offset; 1446 index = pos >> PAGE_SHIFT; 1447 offset = pos & ~PAGE_MASK; 1448 *_start_offset = offset; 1449 1450 count = 1; 1451 if (size > PAGE_SIZE - offset) { 1452 size -= PAGE_SIZE - offset; 1453 count += size >> PAGE_SHIFT; 1454 size &= ~PAGE_MASK; 1455 if (size) 1456 count++; 1457 } 1458 1459 if (count > maxpages) 1460 count = maxpages; 1461 1462 nr = iter_xarray_populate_pages(pages, i->xarray, index, count); 1463 if (nr == 0) 1464 return 0; 1465 1466 return min_t(size_t, nr * PAGE_SIZE - offset, maxsize); 1467 } 1468 1469 /* must be done on non-empty ITER_IOVEC one */ 1470 static unsigned long first_iovec_segment(const struct iov_iter *i, 1471 size_t *size, size_t *start, 1472 size_t maxsize, unsigned maxpages) 1473 { 1474 size_t skip; 1475 long k; 1476 1477 for (k = 0, skip = i->iov_offset; k < i->nr_segs; k++, skip = 0) { 1478 unsigned long addr = (unsigned long)i->iov[k].iov_base + skip; 1479 size_t len = i->iov[k].iov_len - skip; 1480 1481 if (unlikely(!len)) 1482 continue; 1483 if (len > maxsize) 1484 len = maxsize; 1485 len += (*start = addr % PAGE_SIZE); 1486 if (len > maxpages * PAGE_SIZE) 1487 len = maxpages * PAGE_SIZE; 1488 *size = len; 1489 return addr & PAGE_MASK; 1490 } 1491 BUG(); // if it had been empty, we wouldn't get called 1492 } 1493 1494 /* must be done on non-empty ITER_BVEC one */ 1495 static struct page *first_bvec_segment(const struct iov_iter *i, 1496 size_t *size, size_t *start, 1497 size_t maxsize, unsigned maxpages) 1498 { 1499 struct page *page; 1500 size_t skip = i->iov_offset, len; 1501 1502 len = i->bvec->bv_len - skip; 1503 if (len > maxsize) 1504 len = maxsize; 1505 skip += i->bvec->bv_offset; 1506 page = i->bvec->bv_page + skip / PAGE_SIZE; 1507 len += (*start = skip % PAGE_SIZE); 1508 if (len > maxpages * PAGE_SIZE) 1509 len = maxpages * PAGE_SIZE; 1510 *size = len; 1511 return page; 1512 } 1513 1514 ssize_t iov_iter_get_pages(struct iov_iter *i, 1515 struct page **pages, size_t maxsize, unsigned maxpages, 1516 size_t *start) 1517 { 1518 size_t len; 1519 int n, res; 1520 1521 if (maxsize > i->count) 1522 maxsize = i->count; 1523 if (!maxsize) 1524 return 0; 1525 1526 if (likely(iter_is_iovec(i))) { 1527 unsigned int gup_flags = 0; 1528 unsigned long addr; 1529 1530 if (iov_iter_rw(i) != WRITE) 1531 gup_flags |= FOLL_WRITE; 1532 if (i->nofault) 1533 gup_flags |= FOLL_NOFAULT; 1534 1535 addr = first_iovec_segment(i, &len, start, maxsize, maxpages); 1536 n = DIV_ROUND_UP(len, PAGE_SIZE); 1537 res = get_user_pages_fast(addr, n, gup_flags, pages); 1538 if (unlikely(res <= 0)) 1539 return res; 1540 return (res == n ? len : res * PAGE_SIZE) - *start; 1541 } 1542 if (iov_iter_is_bvec(i)) { 1543 struct page *page; 1544 1545 page = first_bvec_segment(i, &len, start, maxsize, maxpages); 1546 n = DIV_ROUND_UP(len, PAGE_SIZE); 1547 while (n--) 1548 get_page(*pages++ = page++); 1549 return len - *start; 1550 } 1551 if (iov_iter_is_pipe(i)) 1552 return pipe_get_pages(i, pages, maxsize, maxpages, start); 1553 if (iov_iter_is_xarray(i)) 1554 return iter_xarray_get_pages(i, pages, maxsize, maxpages, start); 1555 return -EFAULT; 1556 } 1557 EXPORT_SYMBOL(iov_iter_get_pages); 1558 1559 static struct page **get_pages_array(size_t n) 1560 { 1561 return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL); 1562 } 1563 1564 static ssize_t pipe_get_pages_alloc(struct iov_iter *i, 1565 struct page ***pages, size_t maxsize, 1566 size_t *start) 1567 { 1568 struct page **p; 1569 unsigned int iter_head, npages; 1570 ssize_t n; 1571 1572 if (!sanity(i)) 1573 return -EFAULT; 1574 1575 data_start(i, &iter_head, start); 1576 /* Amount of free space: some of this one + all after this one */ 1577 npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe); 1578 n = npages * PAGE_SIZE - *start; 1579 if (maxsize > n) 1580 maxsize = n; 1581 else 1582 npages = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE); 1583 p = get_pages_array(npages); 1584 if (!p) 1585 return -ENOMEM; 1586 n = __pipe_get_pages(i, maxsize, p, iter_head, start); 1587 if (n > 0) 1588 *pages = p; 1589 else 1590 kvfree(p); 1591 return n; 1592 } 1593 1594 static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i, 1595 struct page ***pages, size_t maxsize, 1596 size_t *_start_offset) 1597 { 1598 struct page **p; 1599 unsigned nr, offset; 1600 pgoff_t index, count; 1601 size_t size = maxsize; 1602 loff_t pos; 1603 1604 if (!size) 1605 return 0; 1606 1607 pos = i->xarray_start + i->iov_offset; 1608 index = pos >> PAGE_SHIFT; 1609 offset = pos & ~PAGE_MASK; 1610 *_start_offset = offset; 1611 1612 count = 1; 1613 if (size > PAGE_SIZE - offset) { 1614 size -= PAGE_SIZE - offset; 1615 count += size >> PAGE_SHIFT; 1616 size &= ~PAGE_MASK; 1617 if (size) 1618 count++; 1619 } 1620 1621 p = get_pages_array(count); 1622 if (!p) 1623 return -ENOMEM; 1624 *pages = p; 1625 1626 nr = iter_xarray_populate_pages(p, i->xarray, index, count); 1627 if (nr == 0) 1628 return 0; 1629 1630 return min_t(size_t, nr * PAGE_SIZE - offset, maxsize); 1631 } 1632 1633 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, 1634 struct page ***pages, size_t maxsize, 1635 size_t *start) 1636 { 1637 struct page **p; 1638 size_t len; 1639 int n, res; 1640 1641 if (maxsize > i->count) 1642 maxsize = i->count; 1643 if (!maxsize) 1644 return 0; 1645 1646 if (likely(iter_is_iovec(i))) { 1647 unsigned int gup_flags = 0; 1648 unsigned long addr; 1649 1650 if (iov_iter_rw(i) != WRITE) 1651 gup_flags |= FOLL_WRITE; 1652 if (i->nofault) 1653 gup_flags |= FOLL_NOFAULT; 1654 1655 addr = first_iovec_segment(i, &len, start, maxsize, ~0U); 1656 n = DIV_ROUND_UP(len, PAGE_SIZE); 1657 p = get_pages_array(n); 1658 if (!p) 1659 return -ENOMEM; 1660 res = get_user_pages_fast(addr, n, gup_flags, p); 1661 if (unlikely(res <= 0)) { 1662 kvfree(p); 1663 *pages = NULL; 1664 return res; 1665 } 1666 *pages = p; 1667 return (res == n ? len : res * PAGE_SIZE) - *start; 1668 } 1669 if (iov_iter_is_bvec(i)) { 1670 struct page *page; 1671 1672 page = first_bvec_segment(i, &len, start, maxsize, ~0U); 1673 n = DIV_ROUND_UP(len, PAGE_SIZE); 1674 *pages = p = get_pages_array(n); 1675 if (!p) 1676 return -ENOMEM; 1677 while (n--) 1678 get_page(*p++ = page++); 1679 return len - *start; 1680 } 1681 if (iov_iter_is_pipe(i)) 1682 return pipe_get_pages_alloc(i, pages, maxsize, start); 1683 if (iov_iter_is_xarray(i)) 1684 return iter_xarray_get_pages_alloc(i, pages, maxsize, start); 1685 return -EFAULT; 1686 } 1687 EXPORT_SYMBOL(iov_iter_get_pages_alloc); 1688 1689 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, 1690 struct iov_iter *i) 1691 { 1692 __wsum sum, next; 1693 sum = *csum; 1694 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { 1695 WARN_ON(1); 1696 return 0; 1697 } 1698 iterate_and_advance(i, bytes, base, len, off, ({ 1699 next = csum_and_copy_from_user(base, addr + off, len); 1700 sum = csum_block_add(sum, next, off); 1701 next ? 0 : len; 1702 }), ({ 1703 sum = csum_and_memcpy(addr + off, base, len, sum, off); 1704 }) 1705 ) 1706 *csum = sum; 1707 return bytes; 1708 } 1709 EXPORT_SYMBOL(csum_and_copy_from_iter); 1710 1711 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate, 1712 struct iov_iter *i) 1713 { 1714 struct csum_state *csstate = _csstate; 1715 __wsum sum, next; 1716 1717 if (unlikely(iov_iter_is_discard(i))) { 1718 WARN_ON(1); /* for now */ 1719 return 0; 1720 } 1721 1722 sum = csum_shift(csstate->csum, csstate->off); 1723 if (unlikely(iov_iter_is_pipe(i))) 1724 bytes = csum_and_copy_to_pipe_iter(addr, bytes, i, &sum); 1725 else iterate_and_advance(i, bytes, base, len, off, ({ 1726 next = csum_and_copy_to_user(addr + off, base, len); 1727 sum = csum_block_add(sum, next, off); 1728 next ? 0 : len; 1729 }), ({ 1730 sum = csum_and_memcpy(base, addr + off, len, sum, off); 1731 }) 1732 ) 1733 csstate->csum = csum_shift(sum, csstate->off); 1734 csstate->off += bytes; 1735 return bytes; 1736 } 1737 EXPORT_SYMBOL(csum_and_copy_to_iter); 1738 1739 size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp, 1740 struct iov_iter *i) 1741 { 1742 #ifdef CONFIG_CRYPTO_HASH 1743 struct ahash_request *hash = hashp; 1744 struct scatterlist sg; 1745 size_t copied; 1746 1747 copied = copy_to_iter(addr, bytes, i); 1748 sg_init_one(&sg, addr, copied); 1749 ahash_request_set_crypt(hash, &sg, NULL, copied); 1750 crypto_ahash_update(hash); 1751 return copied; 1752 #else 1753 return 0; 1754 #endif 1755 } 1756 EXPORT_SYMBOL(hash_and_copy_to_iter); 1757 1758 static int iov_npages(const struct iov_iter *i, int maxpages) 1759 { 1760 size_t skip = i->iov_offset, size = i->count; 1761 const struct iovec *p; 1762 int npages = 0; 1763 1764 for (p = i->iov; size; skip = 0, p++) { 1765 unsigned offs = offset_in_page(p->iov_base + skip); 1766 size_t len = min(p->iov_len - skip, size); 1767 1768 if (len) { 1769 size -= len; 1770 npages += DIV_ROUND_UP(offs + len, PAGE_SIZE); 1771 if (unlikely(npages > maxpages)) 1772 return maxpages; 1773 } 1774 } 1775 return npages; 1776 } 1777 1778 static int bvec_npages(const struct iov_iter *i, int maxpages) 1779 { 1780 size_t skip = i->iov_offset, size = i->count; 1781 const struct bio_vec *p; 1782 int npages = 0; 1783 1784 for (p = i->bvec; size; skip = 0, p++) { 1785 unsigned offs = (p->bv_offset + skip) % PAGE_SIZE; 1786 size_t len = min(p->bv_len - skip, size); 1787 1788 size -= len; 1789 npages += DIV_ROUND_UP(offs + len, PAGE_SIZE); 1790 if (unlikely(npages > maxpages)) 1791 return maxpages; 1792 } 1793 return npages; 1794 } 1795 1796 int iov_iter_npages(const struct iov_iter *i, int maxpages) 1797 { 1798 if (unlikely(!i->count)) 1799 return 0; 1800 /* iovec and kvec have identical layouts */ 1801 if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) 1802 return iov_npages(i, maxpages); 1803 if (iov_iter_is_bvec(i)) 1804 return bvec_npages(i, maxpages); 1805 if (iov_iter_is_pipe(i)) { 1806 unsigned int iter_head; 1807 int npages; 1808 size_t off; 1809 1810 if (!sanity(i)) 1811 return 0; 1812 1813 data_start(i, &iter_head, &off); 1814 /* some of this one + all after this one */ 1815 npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe); 1816 return min(npages, maxpages); 1817 } 1818 if (iov_iter_is_xarray(i)) { 1819 unsigned offset = (i->xarray_start + i->iov_offset) % PAGE_SIZE; 1820 int npages = DIV_ROUND_UP(offset + i->count, PAGE_SIZE); 1821 return min(npages, maxpages); 1822 } 1823 return 0; 1824 } 1825 EXPORT_SYMBOL(iov_iter_npages); 1826 1827 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags) 1828 { 1829 *new = *old; 1830 if (unlikely(iov_iter_is_pipe(new))) { 1831 WARN_ON(1); 1832 return NULL; 1833 } 1834 if (unlikely(iov_iter_is_discard(new) || iov_iter_is_xarray(new))) 1835 return NULL; 1836 if (iov_iter_is_bvec(new)) 1837 return new->bvec = kmemdup(new->bvec, 1838 new->nr_segs * sizeof(struct bio_vec), 1839 flags); 1840 else 1841 /* iovec and kvec have identical layout */ 1842 return new->iov = kmemdup(new->iov, 1843 new->nr_segs * sizeof(struct iovec), 1844 flags); 1845 } 1846 EXPORT_SYMBOL(dup_iter); 1847 1848 static int copy_compat_iovec_from_user(struct iovec *iov, 1849 const struct iovec __user *uvec, unsigned long nr_segs) 1850 { 1851 const struct compat_iovec __user *uiov = 1852 (const struct compat_iovec __user *)uvec; 1853 int ret = -EFAULT, i; 1854 1855 if (!user_access_begin(uiov, nr_segs * sizeof(*uiov))) 1856 return -EFAULT; 1857 1858 for (i = 0; i < nr_segs; i++) { 1859 compat_uptr_t buf; 1860 compat_ssize_t len; 1861 1862 unsafe_get_user(len, &uiov[i].iov_len, uaccess_end); 1863 unsafe_get_user(buf, &uiov[i].iov_base, uaccess_end); 1864 1865 /* check for compat_size_t not fitting in compat_ssize_t .. */ 1866 if (len < 0) { 1867 ret = -EINVAL; 1868 goto uaccess_end; 1869 } 1870 iov[i].iov_base = compat_ptr(buf); 1871 iov[i].iov_len = len; 1872 } 1873 1874 ret = 0; 1875 uaccess_end: 1876 user_access_end(); 1877 return ret; 1878 } 1879 1880 static int copy_iovec_from_user(struct iovec *iov, 1881 const struct iovec __user *uvec, unsigned long nr_segs) 1882 { 1883 unsigned long seg; 1884 1885 if (copy_from_user(iov, uvec, nr_segs * sizeof(*uvec))) 1886 return -EFAULT; 1887 for (seg = 0; seg < nr_segs; seg++) { 1888 if ((ssize_t)iov[seg].iov_len < 0) 1889 return -EINVAL; 1890 } 1891 1892 return 0; 1893 } 1894 1895 struct iovec *iovec_from_user(const struct iovec __user *uvec, 1896 unsigned long nr_segs, unsigned long fast_segs, 1897 struct iovec *fast_iov, bool compat) 1898 { 1899 struct iovec *iov = fast_iov; 1900 int ret; 1901 1902 /* 1903 * SuS says "The readv() function *may* fail if the iovcnt argument was 1904 * less than or equal to 0, or greater than {IOV_MAX}. Linux has 1905 * traditionally returned zero for zero segments, so... 1906 */ 1907 if (nr_segs == 0) 1908 return iov; 1909 if (nr_segs > UIO_MAXIOV) 1910 return ERR_PTR(-EINVAL); 1911 if (nr_segs > fast_segs) { 1912 iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL); 1913 if (!iov) 1914 return ERR_PTR(-ENOMEM); 1915 } 1916 1917 if (compat) 1918 ret = copy_compat_iovec_from_user(iov, uvec, nr_segs); 1919 else 1920 ret = copy_iovec_from_user(iov, uvec, nr_segs); 1921 if (ret) { 1922 if (iov != fast_iov) 1923 kfree(iov); 1924 return ERR_PTR(ret); 1925 } 1926 1927 return iov; 1928 } 1929 1930 ssize_t __import_iovec(int type, const struct iovec __user *uvec, 1931 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp, 1932 struct iov_iter *i, bool compat) 1933 { 1934 ssize_t total_len = 0; 1935 unsigned long seg; 1936 struct iovec *iov; 1937 1938 iov = iovec_from_user(uvec, nr_segs, fast_segs, *iovp, compat); 1939 if (IS_ERR(iov)) { 1940 *iovp = NULL; 1941 return PTR_ERR(iov); 1942 } 1943 1944 /* 1945 * According to the Single Unix Specification we should return EINVAL if 1946 * an element length is < 0 when cast to ssize_t or if the total length 1947 * would overflow the ssize_t return value of the system call. 1948 * 1949 * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the 1950 * overflow case. 1951 */ 1952 for (seg = 0; seg < nr_segs; seg++) { 1953 ssize_t len = (ssize_t)iov[seg].iov_len; 1954 1955 if (!access_ok(iov[seg].iov_base, len)) { 1956 if (iov != *iovp) 1957 kfree(iov); 1958 *iovp = NULL; 1959 return -EFAULT; 1960 } 1961 1962 if (len > MAX_RW_COUNT - total_len) { 1963 len = MAX_RW_COUNT - total_len; 1964 iov[seg].iov_len = len; 1965 } 1966 total_len += len; 1967 } 1968 1969 iov_iter_init(i, type, iov, nr_segs, total_len); 1970 if (iov == *iovp) 1971 *iovp = NULL; 1972 else 1973 *iovp = iov; 1974 return total_len; 1975 } 1976 1977 /** 1978 * import_iovec() - Copy an array of &struct iovec from userspace 1979 * into the kernel, check that it is valid, and initialize a new 1980 * &struct iov_iter iterator to access it. 1981 * 1982 * @type: One of %READ or %WRITE. 1983 * @uvec: Pointer to the userspace array. 1984 * @nr_segs: Number of elements in userspace array. 1985 * @fast_segs: Number of elements in @iov. 1986 * @iovp: (input and output parameter) Pointer to pointer to (usually small 1987 * on-stack) kernel array. 1988 * @i: Pointer to iterator that will be initialized on success. 1989 * 1990 * If the array pointed to by *@iov is large enough to hold all @nr_segs, 1991 * then this function places %NULL in *@iov on return. Otherwise, a new 1992 * array will be allocated and the result placed in *@iov. This means that 1993 * the caller may call kfree() on *@iov regardless of whether the small 1994 * on-stack array was used or not (and regardless of whether this function 1995 * returns an error or not). 1996 * 1997 * Return: Negative error code on error, bytes imported on success 1998 */ 1999 ssize_t import_iovec(int type, const struct iovec __user *uvec, 2000 unsigned nr_segs, unsigned fast_segs, 2001 struct iovec **iovp, struct iov_iter *i) 2002 { 2003 return __import_iovec(type, uvec, nr_segs, fast_segs, iovp, i, 2004 in_compat_syscall()); 2005 } 2006 EXPORT_SYMBOL(import_iovec); 2007 2008 int import_single_range(int rw, void __user *buf, size_t len, 2009 struct iovec *iov, struct iov_iter *i) 2010 { 2011 if (len > MAX_RW_COUNT) 2012 len = MAX_RW_COUNT; 2013 if (unlikely(!access_ok(buf, len))) 2014 return -EFAULT; 2015 2016 iov->iov_base = buf; 2017 iov->iov_len = len; 2018 iov_iter_init(i, rw, iov, 1, len); 2019 return 0; 2020 } 2021 EXPORT_SYMBOL(import_single_range); 2022 2023 /** 2024 * iov_iter_restore() - Restore a &struct iov_iter to the same state as when 2025 * iov_iter_save_state() was called. 2026 * 2027 * @i: &struct iov_iter to restore 2028 * @state: state to restore from 2029 * 2030 * Used after iov_iter_save_state() to bring restore @i, if operations may 2031 * have advanced it. 2032 * 2033 * Note: only works on ITER_IOVEC, ITER_BVEC, and ITER_KVEC 2034 */ 2035 void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state) 2036 { 2037 if (WARN_ON_ONCE(!iov_iter_is_bvec(i) && !iter_is_iovec(i)) && 2038 !iov_iter_is_kvec(i)) 2039 return; 2040 i->iov_offset = state->iov_offset; 2041 i->count = state->count; 2042 /* 2043 * For the *vec iters, nr_segs + iov is constant - if we increment 2044 * the vec, then we also decrement the nr_segs count. Hence we don't 2045 * need to track both of these, just one is enough and we can deduct 2046 * the other from that. ITER_KVEC and ITER_IOVEC are the same struct 2047 * size, so we can just increment the iov pointer as they are unionzed. 2048 * ITER_BVEC _may_ be the same size on some archs, but on others it is 2049 * not. Be safe and handle it separately. 2050 */ 2051 BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec)); 2052 if (iov_iter_is_bvec(i)) 2053 i->bvec -= state->nr_segs - i->nr_segs; 2054 else 2055 i->iov -= state->nr_segs - i->nr_segs; 2056 i->nr_segs = state->nr_segs; 2057 } 2058