1 // SPDX-License-Identifier: GPL-2.0-only 2 #include <crypto/hash.h> 3 #include <linux/export.h> 4 #include <linux/bvec.h> 5 #include <linux/fault-inject-usercopy.h> 6 #include <linux/uio.h> 7 #include <linux/pagemap.h> 8 #include <linux/highmem.h> 9 #include <linux/slab.h> 10 #include <linux/vmalloc.h> 11 #include <linux/splice.h> 12 #include <linux/compat.h> 13 #include <net/checksum.h> 14 #include <linux/scatterlist.h> 15 #include <linux/instrumented.h> 16 17 #define PIPE_PARANOIA /* for now */ 18 19 #define iterate_iovec(i, n, __v, __p, skip, STEP) { \ 20 size_t left; \ 21 size_t wanted = n; \ 22 __p = i->iov; \ 23 __v.iov_len = min(n, __p->iov_len - skip); \ 24 if (likely(__v.iov_len)) { \ 25 __v.iov_base = __p->iov_base + skip; \ 26 left = (STEP); \ 27 __v.iov_len -= left; \ 28 skip += __v.iov_len; \ 29 n -= __v.iov_len; \ 30 } else { \ 31 left = 0; \ 32 } \ 33 while (unlikely(!left && n)) { \ 34 __p++; \ 35 __v.iov_len = min(n, __p->iov_len); \ 36 if (unlikely(!__v.iov_len)) \ 37 continue; \ 38 __v.iov_base = __p->iov_base; \ 39 left = (STEP); \ 40 __v.iov_len -= left; \ 41 skip = __v.iov_len; \ 42 n -= __v.iov_len; \ 43 } \ 44 n = wanted - n; \ 45 } 46 47 #define iterate_kvec(i, n, __v, __p, skip, STEP) { \ 48 size_t wanted = n; \ 49 __p = i->kvec; \ 50 __v.iov_len = min(n, __p->iov_len - skip); \ 51 if (likely(__v.iov_len)) { \ 52 __v.iov_base = __p->iov_base + skip; \ 53 (void)(STEP); \ 54 skip += __v.iov_len; \ 55 n -= __v.iov_len; \ 56 } \ 57 while (unlikely(n)) { \ 58 __p++; \ 59 __v.iov_len = min(n, __p->iov_len); \ 60 if (unlikely(!__v.iov_len)) \ 61 continue; \ 62 __v.iov_base = __p->iov_base; \ 63 (void)(STEP); \ 64 skip = __v.iov_len; \ 65 n -= __v.iov_len; \ 66 } \ 67 n = wanted; \ 68 } 69 70 #define iterate_bvec(i, n, __v, __bi, skip, STEP) { \ 71 struct bvec_iter __start; \ 72 __start.bi_size = n; \ 73 __start.bi_bvec_done = skip; \ 74 __start.bi_idx = 0; \ 75 for_each_bvec(__v, i->bvec, __bi, __start) { \ 76 (void)(STEP); \ 77 } \ 78 } 79 80 #define iterate_xarray(i, n, __v, skip, STEP) { \ 81 struct page *head = NULL; \ 82 size_t wanted = n, seg, offset; \ 83 loff_t start = i->xarray_start + skip; \ 84 pgoff_t index = start >> PAGE_SHIFT; \ 85 int j; \ 86 \ 87 XA_STATE(xas, i->xarray, index); \ 88 \ 89 rcu_read_lock(); \ 90 xas_for_each(&xas, head, ULONG_MAX) { \ 91 if (xas_retry(&xas, head)) \ 92 continue; \ 93 if (WARN_ON(xa_is_value(head))) \ 94 break; \ 95 if (WARN_ON(PageHuge(head))) \ 96 break; \ 97 for (j = (head->index < index) ? index - head->index : 0; \ 98 j < thp_nr_pages(head); j++) { \ 99 __v.bv_page = head + j; \ 100 offset = (i->xarray_start + skip) & ~PAGE_MASK; \ 101 seg = PAGE_SIZE - offset; \ 102 __v.bv_offset = offset; \ 103 __v.bv_len = min(n, seg); \ 104 (void)(STEP); \ 105 n -= __v.bv_len; \ 106 skip += __v.bv_len; \ 107 if (n == 0) \ 108 break; \ 109 } \ 110 if (n == 0) \ 111 break; \ 112 } \ 113 rcu_read_unlock(); \ 114 n = wanted - n; \ 115 } 116 117 #define iterate_all_kinds(i, n, v, I, B, K, X) { \ 118 if (likely(n)) { \ 119 size_t skip = i->iov_offset; \ 120 if (likely(iter_is_iovec(i))) { \ 121 const struct iovec *iov; \ 122 struct iovec v; \ 123 iterate_iovec(i, n, v, iov, skip, (I)) \ 124 } else if (iov_iter_is_bvec(i)) { \ 125 struct bio_vec v; \ 126 struct bvec_iter __bi; \ 127 iterate_bvec(i, n, v, __bi, skip, (B)) \ 128 } else if (iov_iter_is_kvec(i)) { \ 129 const struct kvec *kvec; \ 130 struct kvec v; \ 131 iterate_kvec(i, n, v, kvec, skip, (K)) \ 132 } else if (iov_iter_is_xarray(i)) { \ 133 struct bio_vec v; \ 134 iterate_xarray(i, n, v, skip, (X)); \ 135 } \ 136 } \ 137 } 138 139 #define iterate_and_advance(i, n, v, I, B, K, X) { \ 140 if (unlikely(i->count < n)) \ 141 n = i->count; \ 142 if (i->count) { \ 143 size_t skip = i->iov_offset; \ 144 if (likely(iter_is_iovec(i))) { \ 145 const struct iovec *iov; \ 146 struct iovec v; \ 147 iterate_iovec(i, n, v, iov, skip, (I)) \ 148 if (skip == iov->iov_len) { \ 149 iov++; \ 150 skip = 0; \ 151 } \ 152 i->nr_segs -= iov - i->iov; \ 153 i->iov = iov; \ 154 } else if (iov_iter_is_bvec(i)) { \ 155 const struct bio_vec *bvec = i->bvec; \ 156 struct bio_vec v; \ 157 struct bvec_iter __bi; \ 158 iterate_bvec(i, n, v, __bi, skip, (B)) \ 159 i->bvec = __bvec_iter_bvec(i->bvec, __bi); \ 160 i->nr_segs -= i->bvec - bvec; \ 161 skip = __bi.bi_bvec_done; \ 162 } else if (iov_iter_is_kvec(i)) { \ 163 const struct kvec *kvec; \ 164 struct kvec v; \ 165 iterate_kvec(i, n, v, kvec, skip, (K)) \ 166 if (skip == kvec->iov_len) { \ 167 kvec++; \ 168 skip = 0; \ 169 } \ 170 i->nr_segs -= kvec - i->kvec; \ 171 i->kvec = kvec; \ 172 } else if (iov_iter_is_xarray(i)) { \ 173 struct bio_vec v; \ 174 iterate_xarray(i, n, v, skip, (X)) \ 175 } \ 176 i->count -= n; \ 177 i->iov_offset = skip; \ 178 } \ 179 } 180 181 static int copyout(void __user *to, const void *from, size_t n) 182 { 183 if (should_fail_usercopy()) 184 return n; 185 if (access_ok(to, n)) { 186 instrument_copy_to_user(to, from, n); 187 n = raw_copy_to_user(to, from, n); 188 } 189 return n; 190 } 191 192 static int copyin(void *to, const void __user *from, size_t n) 193 { 194 if (should_fail_usercopy()) 195 return n; 196 if (access_ok(from, n)) { 197 instrument_copy_from_user(to, from, n); 198 n = raw_copy_from_user(to, from, n); 199 } 200 return n; 201 } 202 203 static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes, 204 struct iov_iter *i) 205 { 206 size_t skip, copy, left, wanted; 207 const struct iovec *iov; 208 char __user *buf; 209 void *kaddr, *from; 210 211 if (unlikely(bytes > i->count)) 212 bytes = i->count; 213 214 if (unlikely(!bytes)) 215 return 0; 216 217 might_fault(); 218 wanted = bytes; 219 iov = i->iov; 220 skip = i->iov_offset; 221 buf = iov->iov_base + skip; 222 copy = min(bytes, iov->iov_len - skip); 223 224 if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_writeable(buf, copy)) { 225 kaddr = kmap_atomic(page); 226 from = kaddr + offset; 227 228 /* first chunk, usually the only one */ 229 left = copyout(buf, from, copy); 230 copy -= left; 231 skip += copy; 232 from += copy; 233 bytes -= copy; 234 235 while (unlikely(!left && bytes)) { 236 iov++; 237 buf = iov->iov_base; 238 copy = min(bytes, iov->iov_len); 239 left = copyout(buf, from, copy); 240 copy -= left; 241 skip = copy; 242 from += copy; 243 bytes -= copy; 244 } 245 if (likely(!bytes)) { 246 kunmap_atomic(kaddr); 247 goto done; 248 } 249 offset = from - kaddr; 250 buf += copy; 251 kunmap_atomic(kaddr); 252 copy = min(bytes, iov->iov_len - skip); 253 } 254 /* Too bad - revert to non-atomic kmap */ 255 256 kaddr = kmap(page); 257 from = kaddr + offset; 258 left = copyout(buf, from, copy); 259 copy -= left; 260 skip += copy; 261 from += copy; 262 bytes -= copy; 263 while (unlikely(!left && bytes)) { 264 iov++; 265 buf = iov->iov_base; 266 copy = min(bytes, iov->iov_len); 267 left = copyout(buf, from, copy); 268 copy -= left; 269 skip = copy; 270 from += copy; 271 bytes -= copy; 272 } 273 kunmap(page); 274 275 done: 276 if (skip == iov->iov_len) { 277 iov++; 278 skip = 0; 279 } 280 i->count -= wanted - bytes; 281 i->nr_segs -= iov - i->iov; 282 i->iov = iov; 283 i->iov_offset = skip; 284 return wanted - bytes; 285 } 286 287 static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t bytes, 288 struct iov_iter *i) 289 { 290 size_t skip, copy, left, wanted; 291 const struct iovec *iov; 292 char __user *buf; 293 void *kaddr, *to; 294 295 if (unlikely(bytes > i->count)) 296 bytes = i->count; 297 298 if (unlikely(!bytes)) 299 return 0; 300 301 might_fault(); 302 wanted = bytes; 303 iov = i->iov; 304 skip = i->iov_offset; 305 buf = iov->iov_base + skip; 306 copy = min(bytes, iov->iov_len - skip); 307 308 if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_readable(buf, copy)) { 309 kaddr = kmap_atomic(page); 310 to = kaddr + offset; 311 312 /* first chunk, usually the only one */ 313 left = copyin(to, buf, copy); 314 copy -= left; 315 skip += copy; 316 to += copy; 317 bytes -= copy; 318 319 while (unlikely(!left && bytes)) { 320 iov++; 321 buf = iov->iov_base; 322 copy = min(bytes, iov->iov_len); 323 left = copyin(to, buf, copy); 324 copy -= left; 325 skip = copy; 326 to += copy; 327 bytes -= copy; 328 } 329 if (likely(!bytes)) { 330 kunmap_atomic(kaddr); 331 goto done; 332 } 333 offset = to - kaddr; 334 buf += copy; 335 kunmap_atomic(kaddr); 336 copy = min(bytes, iov->iov_len - skip); 337 } 338 /* Too bad - revert to non-atomic kmap */ 339 340 kaddr = kmap(page); 341 to = kaddr + offset; 342 left = copyin(to, buf, copy); 343 copy -= left; 344 skip += copy; 345 to += copy; 346 bytes -= copy; 347 while (unlikely(!left && bytes)) { 348 iov++; 349 buf = iov->iov_base; 350 copy = min(bytes, iov->iov_len); 351 left = copyin(to, buf, copy); 352 copy -= left; 353 skip = copy; 354 to += copy; 355 bytes -= copy; 356 } 357 kunmap(page); 358 359 done: 360 if (skip == iov->iov_len) { 361 iov++; 362 skip = 0; 363 } 364 i->count -= wanted - bytes; 365 i->nr_segs -= iov - i->iov; 366 i->iov = iov; 367 i->iov_offset = skip; 368 return wanted - bytes; 369 } 370 371 #ifdef PIPE_PARANOIA 372 static bool sanity(const struct iov_iter *i) 373 { 374 struct pipe_inode_info *pipe = i->pipe; 375 unsigned int p_head = pipe->head; 376 unsigned int p_tail = pipe->tail; 377 unsigned int p_mask = pipe->ring_size - 1; 378 unsigned int p_occupancy = pipe_occupancy(p_head, p_tail); 379 unsigned int i_head = i->head; 380 unsigned int idx; 381 382 if (i->iov_offset) { 383 struct pipe_buffer *p; 384 if (unlikely(p_occupancy == 0)) 385 goto Bad; // pipe must be non-empty 386 if (unlikely(i_head != p_head - 1)) 387 goto Bad; // must be at the last buffer... 388 389 p = &pipe->bufs[i_head & p_mask]; 390 if (unlikely(p->offset + p->len != i->iov_offset)) 391 goto Bad; // ... at the end of segment 392 } else { 393 if (i_head != p_head) 394 goto Bad; // must be right after the last buffer 395 } 396 return true; 397 Bad: 398 printk(KERN_ERR "idx = %d, offset = %zd\n", i_head, i->iov_offset); 399 printk(KERN_ERR "head = %d, tail = %d, buffers = %d\n", 400 p_head, p_tail, pipe->ring_size); 401 for (idx = 0; idx < pipe->ring_size; idx++) 402 printk(KERN_ERR "[%p %p %d %d]\n", 403 pipe->bufs[idx].ops, 404 pipe->bufs[idx].page, 405 pipe->bufs[idx].offset, 406 pipe->bufs[idx].len); 407 WARN_ON(1); 408 return false; 409 } 410 #else 411 #define sanity(i) true 412 #endif 413 414 static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes, 415 struct iov_iter *i) 416 { 417 struct pipe_inode_info *pipe = i->pipe; 418 struct pipe_buffer *buf; 419 unsigned int p_tail = pipe->tail; 420 unsigned int p_mask = pipe->ring_size - 1; 421 unsigned int i_head = i->head; 422 size_t off; 423 424 if (unlikely(bytes > i->count)) 425 bytes = i->count; 426 427 if (unlikely(!bytes)) 428 return 0; 429 430 if (!sanity(i)) 431 return 0; 432 433 off = i->iov_offset; 434 buf = &pipe->bufs[i_head & p_mask]; 435 if (off) { 436 if (offset == off && buf->page == page) { 437 /* merge with the last one */ 438 buf->len += bytes; 439 i->iov_offset += bytes; 440 goto out; 441 } 442 i_head++; 443 buf = &pipe->bufs[i_head & p_mask]; 444 } 445 if (pipe_full(i_head, p_tail, pipe->max_usage)) 446 return 0; 447 448 buf->ops = &page_cache_pipe_buf_ops; 449 get_page(page); 450 buf->page = page; 451 buf->offset = offset; 452 buf->len = bytes; 453 454 pipe->head = i_head + 1; 455 i->iov_offset = offset + bytes; 456 i->head = i_head; 457 out: 458 i->count -= bytes; 459 return bytes; 460 } 461 462 /* 463 * Fault in one or more iovecs of the given iov_iter, to a maximum length of 464 * bytes. For each iovec, fault in each page that constitutes the iovec. 465 * 466 * Return 0 on success, or non-zero if the memory could not be accessed (i.e. 467 * because it is an invalid address). 468 */ 469 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) 470 { 471 size_t skip = i->iov_offset; 472 const struct iovec *iov; 473 int err; 474 struct iovec v; 475 476 if (iter_is_iovec(i)) { 477 iterate_iovec(i, bytes, v, iov, skip, ({ 478 err = fault_in_pages_readable(v.iov_base, v.iov_len); 479 if (unlikely(err)) 480 return err; 481 0;})) 482 } 483 return 0; 484 } 485 EXPORT_SYMBOL(iov_iter_fault_in_readable); 486 487 void iov_iter_init(struct iov_iter *i, unsigned int direction, 488 const struct iovec *iov, unsigned long nr_segs, 489 size_t count) 490 { 491 WARN_ON(direction & ~(READ | WRITE)); 492 WARN_ON_ONCE(uaccess_kernel()); 493 *i = (struct iov_iter) { 494 .iter_type = ITER_IOVEC, 495 .data_source = direction, 496 .iov = iov, 497 .nr_segs = nr_segs, 498 .iov_offset = 0, 499 .count = count 500 }; 501 } 502 EXPORT_SYMBOL(iov_iter_init); 503 504 static inline bool allocated(struct pipe_buffer *buf) 505 { 506 return buf->ops == &default_pipe_buf_ops; 507 } 508 509 static inline void data_start(const struct iov_iter *i, 510 unsigned int *iter_headp, size_t *offp) 511 { 512 unsigned int p_mask = i->pipe->ring_size - 1; 513 unsigned int iter_head = i->head; 514 size_t off = i->iov_offset; 515 516 if (off && (!allocated(&i->pipe->bufs[iter_head & p_mask]) || 517 off == PAGE_SIZE)) { 518 iter_head++; 519 off = 0; 520 } 521 *iter_headp = iter_head; 522 *offp = off; 523 } 524 525 static size_t push_pipe(struct iov_iter *i, size_t size, 526 int *iter_headp, size_t *offp) 527 { 528 struct pipe_inode_info *pipe = i->pipe; 529 unsigned int p_tail = pipe->tail; 530 unsigned int p_mask = pipe->ring_size - 1; 531 unsigned int iter_head; 532 size_t off; 533 ssize_t left; 534 535 if (unlikely(size > i->count)) 536 size = i->count; 537 if (unlikely(!size)) 538 return 0; 539 540 left = size; 541 data_start(i, &iter_head, &off); 542 *iter_headp = iter_head; 543 *offp = off; 544 if (off) { 545 left -= PAGE_SIZE - off; 546 if (left <= 0) { 547 pipe->bufs[iter_head & p_mask].len += size; 548 return size; 549 } 550 pipe->bufs[iter_head & p_mask].len = PAGE_SIZE; 551 iter_head++; 552 } 553 while (!pipe_full(iter_head, p_tail, pipe->max_usage)) { 554 struct pipe_buffer *buf = &pipe->bufs[iter_head & p_mask]; 555 struct page *page = alloc_page(GFP_USER); 556 if (!page) 557 break; 558 559 buf->ops = &default_pipe_buf_ops; 560 buf->page = page; 561 buf->offset = 0; 562 buf->len = min_t(ssize_t, left, PAGE_SIZE); 563 left -= buf->len; 564 iter_head++; 565 pipe->head = iter_head; 566 567 if (left == 0) 568 return size; 569 } 570 return size - left; 571 } 572 573 static size_t copy_pipe_to_iter(const void *addr, size_t bytes, 574 struct iov_iter *i) 575 { 576 struct pipe_inode_info *pipe = i->pipe; 577 unsigned int p_mask = pipe->ring_size - 1; 578 unsigned int i_head; 579 size_t n, off; 580 581 if (!sanity(i)) 582 return 0; 583 584 bytes = n = push_pipe(i, bytes, &i_head, &off); 585 if (unlikely(!n)) 586 return 0; 587 do { 588 size_t chunk = min_t(size_t, n, PAGE_SIZE - off); 589 memcpy_to_page(pipe->bufs[i_head & p_mask].page, off, addr, chunk); 590 i->head = i_head; 591 i->iov_offset = off + chunk; 592 n -= chunk; 593 addr += chunk; 594 off = 0; 595 i_head++; 596 } while (n); 597 i->count -= bytes; 598 return bytes; 599 } 600 601 static __wsum csum_and_memcpy(void *to, const void *from, size_t len, 602 __wsum sum, size_t off) 603 { 604 __wsum next = csum_partial_copy_nocheck(from, to, len); 605 return csum_block_add(sum, next, off); 606 } 607 608 static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes, 609 struct csum_state *csstate, 610 struct iov_iter *i) 611 { 612 struct pipe_inode_info *pipe = i->pipe; 613 unsigned int p_mask = pipe->ring_size - 1; 614 __wsum sum = csstate->csum; 615 size_t off = csstate->off; 616 unsigned int i_head; 617 size_t n, r; 618 619 if (!sanity(i)) 620 return 0; 621 622 bytes = n = push_pipe(i, bytes, &i_head, &r); 623 if (unlikely(!n)) 624 return 0; 625 do { 626 size_t chunk = min_t(size_t, n, PAGE_SIZE - r); 627 char *p = kmap_atomic(pipe->bufs[i_head & p_mask].page); 628 sum = csum_and_memcpy(p + r, addr, chunk, sum, off); 629 kunmap_atomic(p); 630 i->head = i_head; 631 i->iov_offset = r + chunk; 632 n -= chunk; 633 off += chunk; 634 addr += chunk; 635 r = 0; 636 i_head++; 637 } while (n); 638 i->count -= bytes; 639 csstate->csum = sum; 640 csstate->off = off; 641 return bytes; 642 } 643 644 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i) 645 { 646 const char *from = addr; 647 if (unlikely(iov_iter_is_pipe(i))) 648 return copy_pipe_to_iter(addr, bytes, i); 649 if (iter_is_iovec(i)) 650 might_fault(); 651 iterate_and_advance(i, bytes, v, 652 copyout(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len), 653 memcpy_to_page(v.bv_page, v.bv_offset, 654 (from += v.bv_len) - v.bv_len, v.bv_len), 655 memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len), 656 memcpy_to_page(v.bv_page, v.bv_offset, 657 (from += v.bv_len) - v.bv_len, v.bv_len) 658 ) 659 660 return bytes; 661 } 662 EXPORT_SYMBOL(_copy_to_iter); 663 664 #ifdef CONFIG_ARCH_HAS_COPY_MC 665 static int copyout_mc(void __user *to, const void *from, size_t n) 666 { 667 if (access_ok(to, n)) { 668 instrument_copy_to_user(to, from, n); 669 n = copy_mc_to_user((__force void *) to, from, n); 670 } 671 return n; 672 } 673 674 static unsigned long copy_mc_to_page(struct page *page, size_t offset, 675 const char *from, size_t len) 676 { 677 unsigned long ret; 678 char *to; 679 680 to = kmap_atomic(page); 681 ret = copy_mc_to_kernel(to + offset, from, len); 682 kunmap_atomic(to); 683 684 return ret; 685 } 686 687 static size_t copy_mc_pipe_to_iter(const void *addr, size_t bytes, 688 struct iov_iter *i) 689 { 690 struct pipe_inode_info *pipe = i->pipe; 691 unsigned int p_mask = pipe->ring_size - 1; 692 unsigned int i_head; 693 size_t n, off, xfer = 0; 694 695 if (!sanity(i)) 696 return 0; 697 698 bytes = n = push_pipe(i, bytes, &i_head, &off); 699 if (unlikely(!n)) 700 return 0; 701 do { 702 size_t chunk = min_t(size_t, n, PAGE_SIZE - off); 703 unsigned long rem; 704 705 rem = copy_mc_to_page(pipe->bufs[i_head & p_mask].page, 706 off, addr, chunk); 707 i->head = i_head; 708 i->iov_offset = off + chunk - rem; 709 xfer += chunk - rem; 710 if (rem) 711 break; 712 n -= chunk; 713 addr += chunk; 714 off = 0; 715 i_head++; 716 } while (n); 717 i->count -= xfer; 718 return xfer; 719 } 720 721 /** 722 * _copy_mc_to_iter - copy to iter with source memory error exception handling 723 * @addr: source kernel address 724 * @bytes: total transfer length 725 * @iter: destination iterator 726 * 727 * The pmem driver deploys this for the dax operation 728 * (dax_copy_to_iter()) for dax reads (bypass page-cache and the 729 * block-layer). Upon #MC read(2) aborts and returns EIO or the bytes 730 * successfully copied. 731 * 732 * The main differences between this and typical _copy_to_iter(). 733 * 734 * * Typical tail/residue handling after a fault retries the copy 735 * byte-by-byte until the fault happens again. Re-triggering machine 736 * checks is potentially fatal so the implementation uses source 737 * alignment and poison alignment assumptions to avoid re-triggering 738 * hardware exceptions. 739 * 740 * * ITER_KVEC, ITER_PIPE, and ITER_BVEC can return short copies. 741 * Compare to copy_to_iter() where only ITER_IOVEC attempts might return 742 * a short copy. 743 */ 744 size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i) 745 { 746 const char *from = addr; 747 unsigned long rem, curr_addr, s_addr = (unsigned long) addr; 748 749 if (unlikely(iov_iter_is_pipe(i))) 750 return copy_mc_pipe_to_iter(addr, bytes, i); 751 if (iter_is_iovec(i)) 752 might_fault(); 753 iterate_and_advance(i, bytes, v, 754 copyout_mc(v.iov_base, (from += v.iov_len) - v.iov_len, 755 v.iov_len), 756 ({ 757 rem = copy_mc_to_page(v.bv_page, v.bv_offset, 758 (from += v.bv_len) - v.bv_len, v.bv_len); 759 if (rem) { 760 curr_addr = (unsigned long) from; 761 bytes = curr_addr - s_addr - rem; 762 return bytes; 763 } 764 }), 765 ({ 766 rem = copy_mc_to_kernel(v.iov_base, (from += v.iov_len) 767 - v.iov_len, v.iov_len); 768 if (rem) { 769 curr_addr = (unsigned long) from; 770 bytes = curr_addr - s_addr - rem; 771 return bytes; 772 } 773 }), 774 ({ 775 rem = copy_mc_to_page(v.bv_page, v.bv_offset, 776 (from += v.bv_len) - v.bv_len, v.bv_len); 777 if (rem) { 778 curr_addr = (unsigned long) from; 779 bytes = curr_addr - s_addr - rem; 780 rcu_read_unlock(); 781 i->iov_offset += bytes; 782 i->count -= bytes; 783 return bytes; 784 } 785 }) 786 ) 787 788 return bytes; 789 } 790 EXPORT_SYMBOL_GPL(_copy_mc_to_iter); 791 #endif /* CONFIG_ARCH_HAS_COPY_MC */ 792 793 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) 794 { 795 char *to = addr; 796 if (unlikely(iov_iter_is_pipe(i))) { 797 WARN_ON(1); 798 return 0; 799 } 800 if (iter_is_iovec(i)) 801 might_fault(); 802 iterate_and_advance(i, bytes, v, 803 copyin((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), 804 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page, 805 v.bv_offset, v.bv_len), 806 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), 807 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page, 808 v.bv_offset, v.bv_len) 809 ) 810 811 return bytes; 812 } 813 EXPORT_SYMBOL(_copy_from_iter); 814 815 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i) 816 { 817 char *to = addr; 818 if (unlikely(iov_iter_is_pipe(i))) { 819 WARN_ON(1); 820 return 0; 821 } 822 iterate_and_advance(i, bytes, v, 823 __copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len, 824 v.iov_base, v.iov_len), 825 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page, 826 v.bv_offset, v.bv_len), 827 memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), 828 memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page, 829 v.bv_offset, v.bv_len) 830 ) 831 832 return bytes; 833 } 834 EXPORT_SYMBOL(_copy_from_iter_nocache); 835 836 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE 837 /** 838 * _copy_from_iter_flushcache - write destination through cpu cache 839 * @addr: destination kernel address 840 * @bytes: total transfer length 841 * @iter: source iterator 842 * 843 * The pmem driver arranges for filesystem-dax to use this facility via 844 * dax_copy_from_iter() for ensuring that writes to persistent memory 845 * are flushed through the CPU cache. It is differentiated from 846 * _copy_from_iter_nocache() in that guarantees all data is flushed for 847 * all iterator types. The _copy_from_iter_nocache() only attempts to 848 * bypass the cache for the ITER_IOVEC case, and on some archs may use 849 * instructions that strand dirty-data in the cache. 850 */ 851 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i) 852 { 853 char *to = addr; 854 if (unlikely(iov_iter_is_pipe(i))) { 855 WARN_ON(1); 856 return 0; 857 } 858 iterate_and_advance(i, bytes, v, 859 __copy_from_user_flushcache((to += v.iov_len) - v.iov_len, 860 v.iov_base, v.iov_len), 861 memcpy_page_flushcache((to += v.bv_len) - v.bv_len, v.bv_page, 862 v.bv_offset, v.bv_len), 863 memcpy_flushcache((to += v.iov_len) - v.iov_len, v.iov_base, 864 v.iov_len), 865 memcpy_page_flushcache((to += v.bv_len) - v.bv_len, v.bv_page, 866 v.bv_offset, v.bv_len) 867 ) 868 869 return bytes; 870 } 871 EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache); 872 #endif 873 874 static inline bool page_copy_sane(struct page *page, size_t offset, size_t n) 875 { 876 struct page *head; 877 size_t v = n + offset; 878 879 /* 880 * The general case needs to access the page order in order 881 * to compute the page size. 882 * However, we mostly deal with order-0 pages and thus can 883 * avoid a possible cache line miss for requests that fit all 884 * page orders. 885 */ 886 if (n <= v && v <= PAGE_SIZE) 887 return true; 888 889 head = compound_head(page); 890 v += (page - head) << PAGE_SHIFT; 891 892 if (likely(n <= v && v <= (page_size(head)))) 893 return true; 894 WARN_ON(1); 895 return false; 896 } 897 898 static size_t __copy_page_to_iter(struct page *page, size_t offset, size_t bytes, 899 struct iov_iter *i) 900 { 901 if (likely(iter_is_iovec(i))) 902 return copy_page_to_iter_iovec(page, offset, bytes, i); 903 if (iov_iter_is_bvec(i) || iov_iter_is_kvec(i) || iov_iter_is_xarray(i)) { 904 void *kaddr = kmap_atomic(page); 905 size_t wanted = copy_to_iter(kaddr + offset, bytes, i); 906 kunmap_atomic(kaddr); 907 return wanted; 908 } 909 if (iov_iter_is_pipe(i)) 910 return copy_page_to_iter_pipe(page, offset, bytes, i); 911 if (unlikely(iov_iter_is_discard(i))) { 912 if (unlikely(i->count < bytes)) 913 bytes = i->count; 914 i->count -= bytes; 915 return bytes; 916 } 917 WARN_ON(1); 918 return 0; 919 } 920 921 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, 922 struct iov_iter *i) 923 { 924 size_t res = 0; 925 if (unlikely(!page_copy_sane(page, offset, bytes))) 926 return 0; 927 page += offset / PAGE_SIZE; // first subpage 928 offset %= PAGE_SIZE; 929 while (1) { 930 size_t n = __copy_page_to_iter(page, offset, 931 min(bytes, (size_t)PAGE_SIZE - offset), i); 932 res += n; 933 bytes -= n; 934 if (!bytes || !n) 935 break; 936 offset += n; 937 if (offset == PAGE_SIZE) { 938 page++; 939 offset = 0; 940 } 941 } 942 return res; 943 } 944 EXPORT_SYMBOL(copy_page_to_iter); 945 946 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, 947 struct iov_iter *i) 948 { 949 if (unlikely(!page_copy_sane(page, offset, bytes))) 950 return 0; 951 if (likely(iter_is_iovec(i))) 952 return copy_page_from_iter_iovec(page, offset, bytes, i); 953 if (iov_iter_is_bvec(i) || iov_iter_is_kvec(i) || iov_iter_is_xarray(i)) { 954 void *kaddr = kmap_atomic(page); 955 size_t wanted = _copy_from_iter(kaddr + offset, bytes, i); 956 kunmap_atomic(kaddr); 957 return wanted; 958 } 959 WARN_ON(1); 960 return 0; 961 } 962 EXPORT_SYMBOL(copy_page_from_iter); 963 964 static size_t pipe_zero(size_t bytes, struct iov_iter *i) 965 { 966 struct pipe_inode_info *pipe = i->pipe; 967 unsigned int p_mask = pipe->ring_size - 1; 968 unsigned int i_head; 969 size_t n, off; 970 971 if (!sanity(i)) 972 return 0; 973 974 bytes = n = push_pipe(i, bytes, &i_head, &off); 975 if (unlikely(!n)) 976 return 0; 977 978 do { 979 size_t chunk = min_t(size_t, n, PAGE_SIZE - off); 980 memzero_page(pipe->bufs[i_head & p_mask].page, off, chunk); 981 i->head = i_head; 982 i->iov_offset = off + chunk; 983 n -= chunk; 984 off = 0; 985 i_head++; 986 } while (n); 987 i->count -= bytes; 988 return bytes; 989 } 990 991 size_t iov_iter_zero(size_t bytes, struct iov_iter *i) 992 { 993 if (unlikely(iov_iter_is_pipe(i))) 994 return pipe_zero(bytes, i); 995 iterate_and_advance(i, bytes, v, 996 clear_user(v.iov_base, v.iov_len), 997 memzero_page(v.bv_page, v.bv_offset, v.bv_len), 998 memset(v.iov_base, 0, v.iov_len), 999 memzero_page(v.bv_page, v.bv_offset, v.bv_len) 1000 ) 1001 1002 return bytes; 1003 } 1004 EXPORT_SYMBOL(iov_iter_zero); 1005 1006 size_t iov_iter_copy_from_user_atomic(struct page *page, 1007 struct iov_iter *i, unsigned long offset, size_t bytes) 1008 { 1009 char *kaddr = kmap_atomic(page), *p = kaddr + offset; 1010 if (unlikely(!page_copy_sane(page, offset, bytes))) { 1011 kunmap_atomic(kaddr); 1012 return 0; 1013 } 1014 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { 1015 kunmap_atomic(kaddr); 1016 WARN_ON(1); 1017 return 0; 1018 } 1019 iterate_all_kinds(i, bytes, v, 1020 copyin((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), 1021 memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page, 1022 v.bv_offset, v.bv_len), 1023 memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), 1024 memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page, 1025 v.bv_offset, v.bv_len) 1026 ) 1027 kunmap_atomic(kaddr); 1028 return bytes; 1029 } 1030 EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); 1031 1032 static inline void pipe_truncate(struct iov_iter *i) 1033 { 1034 struct pipe_inode_info *pipe = i->pipe; 1035 unsigned int p_tail = pipe->tail; 1036 unsigned int p_head = pipe->head; 1037 unsigned int p_mask = pipe->ring_size - 1; 1038 1039 if (!pipe_empty(p_head, p_tail)) { 1040 struct pipe_buffer *buf; 1041 unsigned int i_head = i->head; 1042 size_t off = i->iov_offset; 1043 1044 if (off) { 1045 buf = &pipe->bufs[i_head & p_mask]; 1046 buf->len = off - buf->offset; 1047 i_head++; 1048 } 1049 while (p_head != i_head) { 1050 p_head--; 1051 pipe_buf_release(pipe, &pipe->bufs[p_head & p_mask]); 1052 } 1053 1054 pipe->head = p_head; 1055 } 1056 } 1057 1058 static void pipe_advance(struct iov_iter *i, size_t size) 1059 { 1060 struct pipe_inode_info *pipe = i->pipe; 1061 if (size) { 1062 struct pipe_buffer *buf; 1063 unsigned int p_mask = pipe->ring_size - 1; 1064 unsigned int i_head = i->head; 1065 size_t off = i->iov_offset, left = size; 1066 1067 if (off) /* make it relative to the beginning of buffer */ 1068 left += off - pipe->bufs[i_head & p_mask].offset; 1069 while (1) { 1070 buf = &pipe->bufs[i_head & p_mask]; 1071 if (left <= buf->len) 1072 break; 1073 left -= buf->len; 1074 i_head++; 1075 } 1076 i->head = i_head; 1077 i->iov_offset = buf->offset + left; 1078 } 1079 i->count -= size; 1080 /* ... and discard everything past that point */ 1081 pipe_truncate(i); 1082 } 1083 1084 static void iov_iter_bvec_advance(struct iov_iter *i, size_t size) 1085 { 1086 struct bvec_iter bi; 1087 1088 bi.bi_size = i->count; 1089 bi.bi_bvec_done = i->iov_offset; 1090 bi.bi_idx = 0; 1091 bvec_iter_advance(i->bvec, &bi, size); 1092 1093 i->bvec += bi.bi_idx; 1094 i->nr_segs -= bi.bi_idx; 1095 i->count = bi.bi_size; 1096 i->iov_offset = bi.bi_bvec_done; 1097 } 1098 1099 void iov_iter_advance(struct iov_iter *i, size_t size) 1100 { 1101 if (unlikely(i->count < size)) 1102 size = i->count; 1103 if (unlikely(iov_iter_is_pipe(i))) { 1104 pipe_advance(i, size); 1105 return; 1106 } 1107 if (unlikely(iov_iter_is_discard(i))) { 1108 i->count -= size; 1109 return; 1110 } 1111 if (unlikely(iov_iter_is_xarray(i))) { 1112 i->iov_offset += size; 1113 i->count -= size; 1114 return; 1115 } 1116 if (iov_iter_is_bvec(i)) { 1117 iov_iter_bvec_advance(i, size); 1118 return; 1119 } 1120 iterate_and_advance(i, size, v, 0, 0, 0, 0) 1121 } 1122 EXPORT_SYMBOL(iov_iter_advance); 1123 1124 void iov_iter_revert(struct iov_iter *i, size_t unroll) 1125 { 1126 if (!unroll) 1127 return; 1128 if (WARN_ON(unroll > MAX_RW_COUNT)) 1129 return; 1130 i->count += unroll; 1131 if (unlikely(iov_iter_is_pipe(i))) { 1132 struct pipe_inode_info *pipe = i->pipe; 1133 unsigned int p_mask = pipe->ring_size - 1; 1134 unsigned int i_head = i->head; 1135 size_t off = i->iov_offset; 1136 while (1) { 1137 struct pipe_buffer *b = &pipe->bufs[i_head & p_mask]; 1138 size_t n = off - b->offset; 1139 if (unroll < n) { 1140 off -= unroll; 1141 break; 1142 } 1143 unroll -= n; 1144 if (!unroll && i_head == i->start_head) { 1145 off = 0; 1146 break; 1147 } 1148 i_head--; 1149 b = &pipe->bufs[i_head & p_mask]; 1150 off = b->offset + b->len; 1151 } 1152 i->iov_offset = off; 1153 i->head = i_head; 1154 pipe_truncate(i); 1155 return; 1156 } 1157 if (unlikely(iov_iter_is_discard(i))) 1158 return; 1159 if (unroll <= i->iov_offset) { 1160 i->iov_offset -= unroll; 1161 return; 1162 } 1163 unroll -= i->iov_offset; 1164 if (iov_iter_is_xarray(i)) { 1165 BUG(); /* We should never go beyond the start of the specified 1166 * range since we might then be straying into pages that 1167 * aren't pinned. 1168 */ 1169 } else if (iov_iter_is_bvec(i)) { 1170 const struct bio_vec *bvec = i->bvec; 1171 while (1) { 1172 size_t n = (--bvec)->bv_len; 1173 i->nr_segs++; 1174 if (unroll <= n) { 1175 i->bvec = bvec; 1176 i->iov_offset = n - unroll; 1177 return; 1178 } 1179 unroll -= n; 1180 } 1181 } else { /* same logics for iovec and kvec */ 1182 const struct iovec *iov = i->iov; 1183 while (1) { 1184 size_t n = (--iov)->iov_len; 1185 i->nr_segs++; 1186 if (unroll <= n) { 1187 i->iov = iov; 1188 i->iov_offset = n - unroll; 1189 return; 1190 } 1191 unroll -= n; 1192 } 1193 } 1194 } 1195 EXPORT_SYMBOL(iov_iter_revert); 1196 1197 /* 1198 * Return the count of just the current iov_iter segment. 1199 */ 1200 size_t iov_iter_single_seg_count(const struct iov_iter *i) 1201 { 1202 if (i->nr_segs > 1) { 1203 if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) 1204 return min(i->count, i->iov->iov_len - i->iov_offset); 1205 if (iov_iter_is_bvec(i)) 1206 return min(i->count, i->bvec->bv_len - i->iov_offset); 1207 } 1208 return i->count; 1209 } 1210 EXPORT_SYMBOL(iov_iter_single_seg_count); 1211 1212 void iov_iter_kvec(struct iov_iter *i, unsigned int direction, 1213 const struct kvec *kvec, unsigned long nr_segs, 1214 size_t count) 1215 { 1216 WARN_ON(direction & ~(READ | WRITE)); 1217 *i = (struct iov_iter){ 1218 .iter_type = ITER_KVEC, 1219 .data_source = direction, 1220 .kvec = kvec, 1221 .nr_segs = nr_segs, 1222 .iov_offset = 0, 1223 .count = count 1224 }; 1225 } 1226 EXPORT_SYMBOL(iov_iter_kvec); 1227 1228 void iov_iter_bvec(struct iov_iter *i, unsigned int direction, 1229 const struct bio_vec *bvec, unsigned long nr_segs, 1230 size_t count) 1231 { 1232 WARN_ON(direction & ~(READ | WRITE)); 1233 *i = (struct iov_iter){ 1234 .iter_type = ITER_BVEC, 1235 .data_source = direction, 1236 .bvec = bvec, 1237 .nr_segs = nr_segs, 1238 .iov_offset = 0, 1239 .count = count 1240 }; 1241 } 1242 EXPORT_SYMBOL(iov_iter_bvec); 1243 1244 void iov_iter_pipe(struct iov_iter *i, unsigned int direction, 1245 struct pipe_inode_info *pipe, 1246 size_t count) 1247 { 1248 BUG_ON(direction != READ); 1249 WARN_ON(pipe_full(pipe->head, pipe->tail, pipe->ring_size)); 1250 *i = (struct iov_iter){ 1251 .iter_type = ITER_PIPE, 1252 .data_source = false, 1253 .pipe = pipe, 1254 .head = pipe->head, 1255 .start_head = pipe->head, 1256 .iov_offset = 0, 1257 .count = count 1258 }; 1259 } 1260 EXPORT_SYMBOL(iov_iter_pipe); 1261 1262 /** 1263 * iov_iter_xarray - Initialise an I/O iterator to use the pages in an xarray 1264 * @i: The iterator to initialise. 1265 * @direction: The direction of the transfer. 1266 * @xarray: The xarray to access. 1267 * @start: The start file position. 1268 * @count: The size of the I/O buffer in bytes. 1269 * 1270 * Set up an I/O iterator to either draw data out of the pages attached to an 1271 * inode or to inject data into those pages. The pages *must* be prevented 1272 * from evaporation, either by taking a ref on them or locking them by the 1273 * caller. 1274 */ 1275 void iov_iter_xarray(struct iov_iter *i, unsigned int direction, 1276 struct xarray *xarray, loff_t start, size_t count) 1277 { 1278 BUG_ON(direction & ~1); 1279 *i = (struct iov_iter) { 1280 .iter_type = ITER_XARRAY, 1281 .data_source = direction, 1282 .xarray = xarray, 1283 .xarray_start = start, 1284 .count = count, 1285 .iov_offset = 0 1286 }; 1287 } 1288 EXPORT_SYMBOL(iov_iter_xarray); 1289 1290 /** 1291 * iov_iter_discard - Initialise an I/O iterator that discards data 1292 * @i: The iterator to initialise. 1293 * @direction: The direction of the transfer. 1294 * @count: The size of the I/O buffer in bytes. 1295 * 1296 * Set up an I/O iterator that just discards everything that's written to it. 1297 * It's only available as a READ iterator. 1298 */ 1299 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count) 1300 { 1301 BUG_ON(direction != READ); 1302 *i = (struct iov_iter){ 1303 .iter_type = ITER_DISCARD, 1304 .data_source = false, 1305 .count = count, 1306 .iov_offset = 0 1307 }; 1308 } 1309 EXPORT_SYMBOL(iov_iter_discard); 1310 1311 unsigned long iov_iter_alignment(const struct iov_iter *i) 1312 { 1313 unsigned long res = 0; 1314 size_t size = i->count; 1315 1316 if (unlikely(iov_iter_is_pipe(i))) { 1317 unsigned int p_mask = i->pipe->ring_size - 1; 1318 1319 if (size && i->iov_offset && allocated(&i->pipe->bufs[i->head & p_mask])) 1320 return size | i->iov_offset; 1321 return size; 1322 } 1323 if (unlikely(iov_iter_is_xarray(i))) 1324 return (i->xarray_start + i->iov_offset) | i->count; 1325 iterate_all_kinds(i, size, v, 1326 (res |= (unsigned long)v.iov_base | v.iov_len, 0), 1327 res |= v.bv_offset | v.bv_len, 1328 res |= (unsigned long)v.iov_base | v.iov_len, 1329 res |= v.bv_offset | v.bv_len 1330 ) 1331 return res; 1332 } 1333 EXPORT_SYMBOL(iov_iter_alignment); 1334 1335 unsigned long iov_iter_gap_alignment(const struct iov_iter *i) 1336 { 1337 unsigned long res = 0; 1338 size_t size = i->count; 1339 1340 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { 1341 WARN_ON(1); 1342 return ~0U; 1343 } 1344 1345 iterate_all_kinds(i, size, v, 1346 (res |= (!res ? 0 : (unsigned long)v.iov_base) | 1347 (size != v.iov_len ? size : 0), 0), 1348 (res |= (!res ? 0 : (unsigned long)v.bv_offset) | 1349 (size != v.bv_len ? size : 0)), 1350 (res |= (!res ? 0 : (unsigned long)v.iov_base) | 1351 (size != v.iov_len ? size : 0)), 1352 (res |= (!res ? 0 : (unsigned long)v.bv_offset) | 1353 (size != v.bv_len ? size : 0)) 1354 ); 1355 return res; 1356 } 1357 EXPORT_SYMBOL(iov_iter_gap_alignment); 1358 1359 static inline ssize_t __pipe_get_pages(struct iov_iter *i, 1360 size_t maxsize, 1361 struct page **pages, 1362 int iter_head, 1363 size_t *start) 1364 { 1365 struct pipe_inode_info *pipe = i->pipe; 1366 unsigned int p_mask = pipe->ring_size - 1; 1367 ssize_t n = push_pipe(i, maxsize, &iter_head, start); 1368 if (!n) 1369 return -EFAULT; 1370 1371 maxsize = n; 1372 n += *start; 1373 while (n > 0) { 1374 get_page(*pages++ = pipe->bufs[iter_head & p_mask].page); 1375 iter_head++; 1376 n -= PAGE_SIZE; 1377 } 1378 1379 return maxsize; 1380 } 1381 1382 static ssize_t pipe_get_pages(struct iov_iter *i, 1383 struct page **pages, size_t maxsize, unsigned maxpages, 1384 size_t *start) 1385 { 1386 unsigned int iter_head, npages; 1387 size_t capacity; 1388 1389 if (!maxsize) 1390 return 0; 1391 1392 if (!sanity(i)) 1393 return -EFAULT; 1394 1395 data_start(i, &iter_head, start); 1396 /* Amount of free space: some of this one + all after this one */ 1397 npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe); 1398 capacity = min(npages, maxpages) * PAGE_SIZE - *start; 1399 1400 return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start); 1401 } 1402 1403 static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa, 1404 pgoff_t index, unsigned int nr_pages) 1405 { 1406 XA_STATE(xas, xa, index); 1407 struct page *page; 1408 unsigned int ret = 0; 1409 1410 rcu_read_lock(); 1411 for (page = xas_load(&xas); page; page = xas_next(&xas)) { 1412 if (xas_retry(&xas, page)) 1413 continue; 1414 1415 /* Has the page moved or been split? */ 1416 if (unlikely(page != xas_reload(&xas))) { 1417 xas_reset(&xas); 1418 continue; 1419 } 1420 1421 pages[ret] = find_subpage(page, xas.xa_index); 1422 get_page(pages[ret]); 1423 if (++ret == nr_pages) 1424 break; 1425 } 1426 rcu_read_unlock(); 1427 return ret; 1428 } 1429 1430 static ssize_t iter_xarray_get_pages(struct iov_iter *i, 1431 struct page **pages, size_t maxsize, 1432 unsigned maxpages, size_t *_start_offset) 1433 { 1434 unsigned nr, offset; 1435 pgoff_t index, count; 1436 size_t size = maxsize, actual; 1437 loff_t pos; 1438 1439 if (!size || !maxpages) 1440 return 0; 1441 1442 pos = i->xarray_start + i->iov_offset; 1443 index = pos >> PAGE_SHIFT; 1444 offset = pos & ~PAGE_MASK; 1445 *_start_offset = offset; 1446 1447 count = 1; 1448 if (size > PAGE_SIZE - offset) { 1449 size -= PAGE_SIZE - offset; 1450 count += size >> PAGE_SHIFT; 1451 size &= ~PAGE_MASK; 1452 if (size) 1453 count++; 1454 } 1455 1456 if (count > maxpages) 1457 count = maxpages; 1458 1459 nr = iter_xarray_populate_pages(pages, i->xarray, index, count); 1460 if (nr == 0) 1461 return 0; 1462 1463 actual = PAGE_SIZE * nr; 1464 actual -= offset; 1465 if (nr == count && size > 0) { 1466 unsigned last_offset = (nr > 1) ? 0 : offset; 1467 actual -= PAGE_SIZE - (last_offset + size); 1468 } 1469 return actual; 1470 } 1471 1472 ssize_t iov_iter_get_pages(struct iov_iter *i, 1473 struct page **pages, size_t maxsize, unsigned maxpages, 1474 size_t *start) 1475 { 1476 if (maxsize > i->count) 1477 maxsize = i->count; 1478 1479 if (unlikely(iov_iter_is_pipe(i))) 1480 return pipe_get_pages(i, pages, maxsize, maxpages, start); 1481 if (unlikely(iov_iter_is_xarray(i))) 1482 return iter_xarray_get_pages(i, pages, maxsize, maxpages, start); 1483 if (unlikely(iov_iter_is_discard(i))) 1484 return -EFAULT; 1485 1486 iterate_all_kinds(i, maxsize, v, ({ 1487 unsigned long addr = (unsigned long)v.iov_base; 1488 size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1)); 1489 int n; 1490 int res; 1491 1492 if (len > maxpages * PAGE_SIZE) 1493 len = maxpages * PAGE_SIZE; 1494 addr &= ~(PAGE_SIZE - 1); 1495 n = DIV_ROUND_UP(len, PAGE_SIZE); 1496 res = get_user_pages_fast(addr, n, 1497 iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0, 1498 pages); 1499 if (unlikely(res < 0)) 1500 return res; 1501 return (res == n ? len : res * PAGE_SIZE) - *start; 1502 0;}),({ 1503 /* can't be more than PAGE_SIZE */ 1504 *start = v.bv_offset; 1505 get_page(*pages = v.bv_page); 1506 return v.bv_len; 1507 }),({ 1508 return -EFAULT; 1509 }), 1510 0 1511 ) 1512 return 0; 1513 } 1514 EXPORT_SYMBOL(iov_iter_get_pages); 1515 1516 static struct page **get_pages_array(size_t n) 1517 { 1518 return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL); 1519 } 1520 1521 static ssize_t pipe_get_pages_alloc(struct iov_iter *i, 1522 struct page ***pages, size_t maxsize, 1523 size_t *start) 1524 { 1525 struct page **p; 1526 unsigned int iter_head, npages; 1527 ssize_t n; 1528 1529 if (!maxsize) 1530 return 0; 1531 1532 if (!sanity(i)) 1533 return -EFAULT; 1534 1535 data_start(i, &iter_head, start); 1536 /* Amount of free space: some of this one + all after this one */ 1537 npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe); 1538 n = npages * PAGE_SIZE - *start; 1539 if (maxsize > n) 1540 maxsize = n; 1541 else 1542 npages = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE); 1543 p = get_pages_array(npages); 1544 if (!p) 1545 return -ENOMEM; 1546 n = __pipe_get_pages(i, maxsize, p, iter_head, start); 1547 if (n > 0) 1548 *pages = p; 1549 else 1550 kvfree(p); 1551 return n; 1552 } 1553 1554 static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i, 1555 struct page ***pages, size_t maxsize, 1556 size_t *_start_offset) 1557 { 1558 struct page **p; 1559 unsigned nr, offset; 1560 pgoff_t index, count; 1561 size_t size = maxsize, actual; 1562 loff_t pos; 1563 1564 if (!size) 1565 return 0; 1566 1567 pos = i->xarray_start + i->iov_offset; 1568 index = pos >> PAGE_SHIFT; 1569 offset = pos & ~PAGE_MASK; 1570 *_start_offset = offset; 1571 1572 count = 1; 1573 if (size > PAGE_SIZE - offset) { 1574 size -= PAGE_SIZE - offset; 1575 count += size >> PAGE_SHIFT; 1576 size &= ~PAGE_MASK; 1577 if (size) 1578 count++; 1579 } 1580 1581 p = get_pages_array(count); 1582 if (!p) 1583 return -ENOMEM; 1584 *pages = p; 1585 1586 nr = iter_xarray_populate_pages(p, i->xarray, index, count); 1587 if (nr == 0) 1588 return 0; 1589 1590 actual = PAGE_SIZE * nr; 1591 actual -= offset; 1592 if (nr == count && size > 0) { 1593 unsigned last_offset = (nr > 1) ? 0 : offset; 1594 actual -= PAGE_SIZE - (last_offset + size); 1595 } 1596 return actual; 1597 } 1598 1599 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, 1600 struct page ***pages, size_t maxsize, 1601 size_t *start) 1602 { 1603 struct page **p; 1604 1605 if (maxsize > i->count) 1606 maxsize = i->count; 1607 1608 if (unlikely(iov_iter_is_pipe(i))) 1609 return pipe_get_pages_alloc(i, pages, maxsize, start); 1610 if (unlikely(iov_iter_is_xarray(i))) 1611 return iter_xarray_get_pages_alloc(i, pages, maxsize, start); 1612 if (unlikely(iov_iter_is_discard(i))) 1613 return -EFAULT; 1614 1615 iterate_all_kinds(i, maxsize, v, ({ 1616 unsigned long addr = (unsigned long)v.iov_base; 1617 size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1)); 1618 int n; 1619 int res; 1620 1621 addr &= ~(PAGE_SIZE - 1); 1622 n = DIV_ROUND_UP(len, PAGE_SIZE); 1623 p = get_pages_array(n); 1624 if (!p) 1625 return -ENOMEM; 1626 res = get_user_pages_fast(addr, n, 1627 iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0, p); 1628 if (unlikely(res < 0)) { 1629 kvfree(p); 1630 return res; 1631 } 1632 *pages = p; 1633 return (res == n ? len : res * PAGE_SIZE) - *start; 1634 0;}),({ 1635 /* can't be more than PAGE_SIZE */ 1636 *start = v.bv_offset; 1637 *pages = p = get_pages_array(1); 1638 if (!p) 1639 return -ENOMEM; 1640 get_page(*p = v.bv_page); 1641 return v.bv_len; 1642 }),({ 1643 return -EFAULT; 1644 }), 0 1645 ) 1646 return 0; 1647 } 1648 EXPORT_SYMBOL(iov_iter_get_pages_alloc); 1649 1650 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, 1651 struct iov_iter *i) 1652 { 1653 char *to = addr; 1654 __wsum sum, next; 1655 size_t off = 0; 1656 sum = *csum; 1657 if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { 1658 WARN_ON(1); 1659 return 0; 1660 } 1661 iterate_and_advance(i, bytes, v, ({ 1662 next = csum_and_copy_from_user(v.iov_base, 1663 (to += v.iov_len) - v.iov_len, 1664 v.iov_len); 1665 if (next) { 1666 sum = csum_block_add(sum, next, off); 1667 off += v.iov_len; 1668 } 1669 next ? 0 : v.iov_len; 1670 }), ({ 1671 char *p = kmap_atomic(v.bv_page); 1672 sum = csum_and_memcpy((to += v.bv_len) - v.bv_len, 1673 p + v.bv_offset, v.bv_len, 1674 sum, off); 1675 kunmap_atomic(p); 1676 off += v.bv_len; 1677 }),({ 1678 sum = csum_and_memcpy((to += v.iov_len) - v.iov_len, 1679 v.iov_base, v.iov_len, 1680 sum, off); 1681 off += v.iov_len; 1682 }), ({ 1683 char *p = kmap_atomic(v.bv_page); 1684 sum = csum_and_memcpy((to += v.bv_len) - v.bv_len, 1685 p + v.bv_offset, v.bv_len, 1686 sum, off); 1687 kunmap_atomic(p); 1688 off += v.bv_len; 1689 }) 1690 ) 1691 *csum = sum; 1692 return bytes; 1693 } 1694 EXPORT_SYMBOL(csum_and_copy_from_iter); 1695 1696 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate, 1697 struct iov_iter *i) 1698 { 1699 struct csum_state *csstate = _csstate; 1700 const char *from = addr; 1701 __wsum sum, next; 1702 size_t off; 1703 1704 if (unlikely(iov_iter_is_pipe(i))) 1705 return csum_and_copy_to_pipe_iter(addr, bytes, _csstate, i); 1706 1707 sum = csstate->csum; 1708 off = csstate->off; 1709 if (unlikely(iov_iter_is_discard(i))) { 1710 WARN_ON(1); /* for now */ 1711 return 0; 1712 } 1713 iterate_and_advance(i, bytes, v, ({ 1714 next = csum_and_copy_to_user((from += v.iov_len) - v.iov_len, 1715 v.iov_base, 1716 v.iov_len); 1717 if (next) { 1718 sum = csum_block_add(sum, next, off); 1719 off += v.iov_len; 1720 } 1721 next ? 0 : v.iov_len; 1722 }), ({ 1723 char *p = kmap_atomic(v.bv_page); 1724 sum = csum_and_memcpy(p + v.bv_offset, 1725 (from += v.bv_len) - v.bv_len, 1726 v.bv_len, sum, off); 1727 kunmap_atomic(p); 1728 off += v.bv_len; 1729 }),({ 1730 sum = csum_and_memcpy(v.iov_base, 1731 (from += v.iov_len) - v.iov_len, 1732 v.iov_len, sum, off); 1733 off += v.iov_len; 1734 }), ({ 1735 char *p = kmap_atomic(v.bv_page); 1736 sum = csum_and_memcpy(p + v.bv_offset, 1737 (from += v.bv_len) - v.bv_len, 1738 v.bv_len, sum, off); 1739 kunmap_atomic(p); 1740 off += v.bv_len; 1741 }) 1742 ) 1743 csstate->csum = sum; 1744 csstate->off = off; 1745 return bytes; 1746 } 1747 EXPORT_SYMBOL(csum_and_copy_to_iter); 1748 1749 size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp, 1750 struct iov_iter *i) 1751 { 1752 #ifdef CONFIG_CRYPTO_HASH 1753 struct ahash_request *hash = hashp; 1754 struct scatterlist sg; 1755 size_t copied; 1756 1757 copied = copy_to_iter(addr, bytes, i); 1758 sg_init_one(&sg, addr, copied); 1759 ahash_request_set_crypt(hash, &sg, NULL, copied); 1760 crypto_ahash_update(hash); 1761 return copied; 1762 #else 1763 return 0; 1764 #endif 1765 } 1766 EXPORT_SYMBOL(hash_and_copy_to_iter); 1767 1768 int iov_iter_npages(const struct iov_iter *i, int maxpages) 1769 { 1770 size_t size = i->count; 1771 int npages = 0; 1772 1773 if (!size) 1774 return 0; 1775 if (unlikely(iov_iter_is_discard(i))) 1776 return 0; 1777 1778 if (unlikely(iov_iter_is_pipe(i))) { 1779 struct pipe_inode_info *pipe = i->pipe; 1780 unsigned int iter_head; 1781 size_t off; 1782 1783 if (!sanity(i)) 1784 return 0; 1785 1786 data_start(i, &iter_head, &off); 1787 /* some of this one + all after this one */ 1788 npages = pipe_space_for_user(iter_head, pipe->tail, pipe); 1789 if (npages >= maxpages) 1790 return maxpages; 1791 } else if (unlikely(iov_iter_is_xarray(i))) { 1792 unsigned offset; 1793 1794 offset = (i->xarray_start + i->iov_offset) & ~PAGE_MASK; 1795 1796 npages = 1; 1797 if (size > PAGE_SIZE - offset) { 1798 size -= PAGE_SIZE - offset; 1799 npages += size >> PAGE_SHIFT; 1800 size &= ~PAGE_MASK; 1801 if (size) 1802 npages++; 1803 } 1804 if (npages >= maxpages) 1805 return maxpages; 1806 } else iterate_all_kinds(i, size, v, ({ 1807 unsigned long p = (unsigned long)v.iov_base; 1808 npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE) 1809 - p / PAGE_SIZE; 1810 if (npages >= maxpages) 1811 return maxpages; 1812 0;}),({ 1813 npages++; 1814 if (npages >= maxpages) 1815 return maxpages; 1816 }),({ 1817 unsigned long p = (unsigned long)v.iov_base; 1818 npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE) 1819 - p / PAGE_SIZE; 1820 if (npages >= maxpages) 1821 return maxpages; 1822 }), 1823 0 1824 ) 1825 return npages; 1826 } 1827 EXPORT_SYMBOL(iov_iter_npages); 1828 1829 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags) 1830 { 1831 *new = *old; 1832 if (unlikely(iov_iter_is_pipe(new))) { 1833 WARN_ON(1); 1834 return NULL; 1835 } 1836 if (unlikely(iov_iter_is_discard(new) || iov_iter_is_xarray(new))) 1837 return NULL; 1838 if (iov_iter_is_bvec(new)) 1839 return new->bvec = kmemdup(new->bvec, 1840 new->nr_segs * sizeof(struct bio_vec), 1841 flags); 1842 else 1843 /* iovec and kvec have identical layout */ 1844 return new->iov = kmemdup(new->iov, 1845 new->nr_segs * sizeof(struct iovec), 1846 flags); 1847 } 1848 EXPORT_SYMBOL(dup_iter); 1849 1850 static int copy_compat_iovec_from_user(struct iovec *iov, 1851 const struct iovec __user *uvec, unsigned long nr_segs) 1852 { 1853 const struct compat_iovec __user *uiov = 1854 (const struct compat_iovec __user *)uvec; 1855 int ret = -EFAULT, i; 1856 1857 if (!user_access_begin(uiov, nr_segs * sizeof(*uiov))) 1858 return -EFAULT; 1859 1860 for (i = 0; i < nr_segs; i++) { 1861 compat_uptr_t buf; 1862 compat_ssize_t len; 1863 1864 unsafe_get_user(len, &uiov[i].iov_len, uaccess_end); 1865 unsafe_get_user(buf, &uiov[i].iov_base, uaccess_end); 1866 1867 /* check for compat_size_t not fitting in compat_ssize_t .. */ 1868 if (len < 0) { 1869 ret = -EINVAL; 1870 goto uaccess_end; 1871 } 1872 iov[i].iov_base = compat_ptr(buf); 1873 iov[i].iov_len = len; 1874 } 1875 1876 ret = 0; 1877 uaccess_end: 1878 user_access_end(); 1879 return ret; 1880 } 1881 1882 static int copy_iovec_from_user(struct iovec *iov, 1883 const struct iovec __user *uvec, unsigned long nr_segs) 1884 { 1885 unsigned long seg; 1886 1887 if (copy_from_user(iov, uvec, nr_segs * sizeof(*uvec))) 1888 return -EFAULT; 1889 for (seg = 0; seg < nr_segs; seg++) { 1890 if ((ssize_t)iov[seg].iov_len < 0) 1891 return -EINVAL; 1892 } 1893 1894 return 0; 1895 } 1896 1897 struct iovec *iovec_from_user(const struct iovec __user *uvec, 1898 unsigned long nr_segs, unsigned long fast_segs, 1899 struct iovec *fast_iov, bool compat) 1900 { 1901 struct iovec *iov = fast_iov; 1902 int ret; 1903 1904 /* 1905 * SuS says "The readv() function *may* fail if the iovcnt argument was 1906 * less than or equal to 0, or greater than {IOV_MAX}. Linux has 1907 * traditionally returned zero for zero segments, so... 1908 */ 1909 if (nr_segs == 0) 1910 return iov; 1911 if (nr_segs > UIO_MAXIOV) 1912 return ERR_PTR(-EINVAL); 1913 if (nr_segs > fast_segs) { 1914 iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL); 1915 if (!iov) 1916 return ERR_PTR(-ENOMEM); 1917 } 1918 1919 if (compat) 1920 ret = copy_compat_iovec_from_user(iov, uvec, nr_segs); 1921 else 1922 ret = copy_iovec_from_user(iov, uvec, nr_segs); 1923 if (ret) { 1924 if (iov != fast_iov) 1925 kfree(iov); 1926 return ERR_PTR(ret); 1927 } 1928 1929 return iov; 1930 } 1931 1932 ssize_t __import_iovec(int type, const struct iovec __user *uvec, 1933 unsigned nr_segs, unsigned fast_segs, struct iovec **iovp, 1934 struct iov_iter *i, bool compat) 1935 { 1936 ssize_t total_len = 0; 1937 unsigned long seg; 1938 struct iovec *iov; 1939 1940 iov = iovec_from_user(uvec, nr_segs, fast_segs, *iovp, compat); 1941 if (IS_ERR(iov)) { 1942 *iovp = NULL; 1943 return PTR_ERR(iov); 1944 } 1945 1946 /* 1947 * According to the Single Unix Specification we should return EINVAL if 1948 * an element length is < 0 when cast to ssize_t or if the total length 1949 * would overflow the ssize_t return value of the system call. 1950 * 1951 * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the 1952 * overflow case. 1953 */ 1954 for (seg = 0; seg < nr_segs; seg++) { 1955 ssize_t len = (ssize_t)iov[seg].iov_len; 1956 1957 if (!access_ok(iov[seg].iov_base, len)) { 1958 if (iov != *iovp) 1959 kfree(iov); 1960 *iovp = NULL; 1961 return -EFAULT; 1962 } 1963 1964 if (len > MAX_RW_COUNT - total_len) { 1965 len = MAX_RW_COUNT - total_len; 1966 iov[seg].iov_len = len; 1967 } 1968 total_len += len; 1969 } 1970 1971 iov_iter_init(i, type, iov, nr_segs, total_len); 1972 if (iov == *iovp) 1973 *iovp = NULL; 1974 else 1975 *iovp = iov; 1976 return total_len; 1977 } 1978 1979 /** 1980 * import_iovec() - Copy an array of &struct iovec from userspace 1981 * into the kernel, check that it is valid, and initialize a new 1982 * &struct iov_iter iterator to access it. 1983 * 1984 * @type: One of %READ or %WRITE. 1985 * @uvec: Pointer to the userspace array. 1986 * @nr_segs: Number of elements in userspace array. 1987 * @fast_segs: Number of elements in @iov. 1988 * @iovp: (input and output parameter) Pointer to pointer to (usually small 1989 * on-stack) kernel array. 1990 * @i: Pointer to iterator that will be initialized on success. 1991 * 1992 * If the array pointed to by *@iov is large enough to hold all @nr_segs, 1993 * then this function places %NULL in *@iov on return. Otherwise, a new 1994 * array will be allocated and the result placed in *@iov. This means that 1995 * the caller may call kfree() on *@iov regardless of whether the small 1996 * on-stack array was used or not (and regardless of whether this function 1997 * returns an error or not). 1998 * 1999 * Return: Negative error code on error, bytes imported on success 2000 */ 2001 ssize_t import_iovec(int type, const struct iovec __user *uvec, 2002 unsigned nr_segs, unsigned fast_segs, 2003 struct iovec **iovp, struct iov_iter *i) 2004 { 2005 return __import_iovec(type, uvec, nr_segs, fast_segs, iovp, i, 2006 in_compat_syscall()); 2007 } 2008 EXPORT_SYMBOL(import_iovec); 2009 2010 int import_single_range(int rw, void __user *buf, size_t len, 2011 struct iovec *iov, struct iov_iter *i) 2012 { 2013 if (len > MAX_RW_COUNT) 2014 len = MAX_RW_COUNT; 2015 if (unlikely(!access_ok(buf, len))) 2016 return -EFAULT; 2017 2018 iov->iov_base = buf; 2019 iov->iov_len = len; 2020 iov_iter_init(i, rw, iov, 1, len); 2021 return 0; 2022 } 2023 EXPORT_SYMBOL(import_single_range); 2024