fs/remap_range.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/slab.h>
   3 #include <linux/stat.h>
   4 #include <linux/sched/xacct.h>
   5 #include <linux/fcntl.h>
   6 #include <linux/file.h>
   7 #include <linux/uio.h>
   8 #include <linux/fsnotify.h>
   9 #include <linux/security.h>
  10 #include <linux/export.h>
  11 #include <linux/syscalls.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/splice.h>
  14 #include <linux/compat.h>
  15 #include <linux/mount.h>
  16 #include <linux/fs.h>
  17 #include <linux/dax.h>
  18 #include <linux/overflow.h>
  19 #include "internal.h"
  20
  21 #include <linux/uaccess.h>
  22 #include <asm/unistd.h>
  23
  24 /*
  25  * Performs necessary checks before doing a clone.
  26  *
  27  * Can adjust amount of bytes to clone via @req_count argument.
  28  * Returns appropriate error code that caller should return or
  29  * zero in case the clone should be allowed.
  30  */
  31 static int generic_remap_checks(struct file *file_in, loff_t pos_in,
  32                                 struct file *file_out, loff_t pos_out,
  33                                 loff_t *req_count, unsigned int remap_flags)
  34 {
  35         struct inode *inode_in = file_in->f_mapping->host;
  36         struct inode *inode_out = file_out->f_mapping->host;
  37         uint64_t count = *req_count;
  38         uint64_t bcount;
  39         loff_t size_in, size_out;
  40         loff_t bs = inode_out->i_sb->s_blocksize;
  41         int ret;
  42
  43         /* The start of both ranges must be aligned to an fs block. */
  44         if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_out, bs))
  45                 return -EINVAL;
  46
  47         /* Ensure offsets don't wrap. */
  48         if (pos_in + count < pos_in || pos_out + count < pos_out)
  49                 return -EINVAL;
  50
  51         size_in = i_size_read(inode_in);
  52         size_out = i_size_read(inode_out);
  53
  54         /* Dedupe requires both ranges to be within EOF. */
  55         if ((remap_flags & REMAP_FILE_DEDUP) &&
  56             (pos_in >= size_in || pos_in + count > size_in ||
  57              pos_out >= size_out || pos_out + count > size_out))
  58                 return -EINVAL;
  59
  60         /* Ensure the infile range is within the infile. */
  61         if (pos_in >= size_in)
  62                 return -EINVAL;
  63         count = min(count, size_in - (uint64_t)pos_in);
  64
  65         ret = generic_write_check_limits(file_out, pos_out, &count);
  66         if (ret)
  67                 return ret;
  68
  69         /*
  70          * If the user wanted us to link to the infile's EOF, round up to the
  71          * next block boundary for this check.
  72          *
  73          * Otherwise, make sure the count is also block-aligned, having
  74          * already confirmed the starting offsets' block alignment.
  75          */
  76         if (pos_in + count == size_in &&
  77             (!(remap_flags & REMAP_FILE_DEDUP) || pos_out + count == size_out)) {
  78                 bcount = ALIGN(size_in, bs) - pos_in;
  79         } else {
  80                 if (!IS_ALIGNED(count, bs))
  81                         count = ALIGN_DOWN(count, bs);
  82                 bcount = count;
  83         }
  84
  85         /* Don't allow overlapped cloning within the same file. */
  86         if (inode_in == inode_out &&
  87             pos_out + bcount > pos_in &&
  88             pos_out < pos_in + bcount)
  89                 return -EINVAL;
  90
  91         /*
  92          * We shortened the request but the caller can't deal with that, so
  93          * bounce the request back to userspace.
  94          */
  95         if (*req_count != count && !(remap_flags & REMAP_FILE_CAN_SHORTEN))
  96                 return -EINVAL;
  97
  98         *req_count = count;
  99         return 0;
 100 }
 101
 102 int remap_verify_area(struct file *file, loff_t pos, loff_t len, bool write)
 103 {
 104         int mask = write ? MAY_WRITE : MAY_READ;
 105         loff_t tmp;
 106         int ret;
 107
 108         if (unlikely(pos < 0 || len < 0))
 109                 return -EINVAL;
 110
 111         if (unlikely(check_add_overflow(pos, len, &tmp)))
 112                 return -EINVAL;
 113
 114         ret = security_file_permission(file, mask);
 115         if (ret)
 116                 return ret;
 117
 118         return fsnotify_file_area_perm(file, mask, &pos, len);
 119 }
 120 EXPORT_SYMBOL_GPL(remap_verify_area);
 121
 122 /*
 123  * Ensure that we don't remap a partial EOF block in the middle of something
 124  * else.  Assume that the offsets have already been checked for block
 125  * alignment.
 126  *
 127  * For clone we only link a partial EOF block above or at the destination file's
 128  * EOF.  For deduplication we accept a partial EOF block only if it ends at the
 129  * destination file's EOF (can not link it into the middle of a file).
 130  *
 131  * Shorten the request if possible.
 132  */
 133 static int generic_remap_check_len(struct inode *inode_in,
 134                                    struct inode *inode_out,
 135                                    loff_t pos_out,
 136                                    loff_t *len,
 137                                    unsigned int remap_flags)
 138 {
 139         u64 blkmask = i_blocksize(inode_in) - 1;
 140         loff_t new_len = *len;
 141
 142         if ((*len & blkmask) == 0)
 143                 return 0;
 144
 145         if (pos_out + *len < i_size_read(inode_out))
 146                 new_len &= ~blkmask;
 147
 148         if (new_len == *len)
 149                 return 0;
 150
 151         if (remap_flags & REMAP_FILE_CAN_SHORTEN) {
 152                 *len = new_len;
 153                 return 0;
 154         }
 155
 156         return (remap_flags & REMAP_FILE_DEDUP) ? -EBADE : -EINVAL;
 157 }
 158
 159 /* Read a page's worth of file data into the page cache. */
 160 static struct folio *vfs_dedupe_get_folio(struct file *file, loff_t pos)
 161 {
 162         return read_mapping_folio(file->f_mapping, pos >> PAGE_SHIFT, file);
 163 }
 164
 165 /*
 166  * Lock two folios, ensuring that we lock in offset order if the folios
 167  * are from the same file.
 168  */
 169 static void vfs_lock_two_folios(struct folio *folio1, struct folio *folio2)
 170 {
 171         /* Always lock in order of increasing index. */
 172         if (folio1->index > folio2->index)
 173                 swap(folio1, folio2);
 174
 175         folio_lock(folio1);
 176         if (folio1 != folio2)
 177                 folio_lock(folio2);
 178 }
 179
 180 /* Unlock two folios, being careful not to unlock the same folio twice. */
 181 static void vfs_unlock_two_folios(struct folio *folio1, struct folio *folio2)
 182 {
 183         folio_unlock(folio1);
 184         if (folio1 != folio2)
 185                 folio_unlock(folio2);
 186 }
 187
 188 /*
 189  * Compare extents of two files to see if they are the same.
 190  * Caller must have locked both inodes to prevent write races.
 191  */
 192 static int vfs_dedupe_file_range_compare(struct file *src, loff_t srcoff,
 193                                          struct file *dest, loff_t dstoff,
 194                                          loff_t len, bool *is_same)
 195 {
 196         bool same = true;
 197         int error = -EINVAL;
 198
 199         while (len) {
 200                 struct folio *src_folio, *dst_folio;
 201                 void *src_addr, *dst_addr;
 202                 loff_t cmp_len = min(PAGE_SIZE - offset_in_page(srcoff),
 203                                      PAGE_SIZE - offset_in_page(dstoff));
 204
 205                 cmp_len = min(cmp_len, len);
 206                 if (cmp_len <= 0)
 207                         goto out_error;
 208
 209                 src_folio = vfs_dedupe_get_folio(src, srcoff);
 210                 if (IS_ERR(src_folio)) {
 211                         error = PTR_ERR(src_folio);
 212                         goto out_error;
 213                 }
 214                 dst_folio = vfs_dedupe_get_folio(dest, dstoff);
 215                 if (IS_ERR(dst_folio)) {
 216                         error = PTR_ERR(dst_folio);
 217                         folio_put(src_folio);
 218                         goto out_error;
 219                 }
 220
 221                 vfs_lock_two_folios(src_folio, dst_folio);
 222
 223                 /*
 224                  * Now that we've locked both folios, make sure they're still
 225                  * mapped to the file data we're interested in.  If not,
 226                  * someone is invalidating pages on us and we lose.
 227                  */
 228                 if (!folio_test_uptodate(src_folio) || !folio_test_uptodate(dst_folio) ||
 229                     src_folio->mapping != src->f_mapping ||
 230                     dst_folio->mapping != dest->f_mapping) {
 231                         same = false;
 232                         goto unlock;
 233                 }
 234
 235                 src_addr = kmap_local_folio(src_folio,
 236                                         offset_in_folio(src_folio, srcoff));
 237                 dst_addr = kmap_local_folio(dst_folio,
 238                                         offset_in_folio(dst_folio, dstoff));
 239
 240                 flush_dcache_folio(src_folio);
 241                 flush_dcache_folio(dst_folio);
 242
 243                 if (memcmp(src_addr, dst_addr, cmp_len))
 244                         same = false;
 245
 246                 kunmap_local(dst_addr);
 247                 kunmap_local(src_addr);
 248 unlock:
 249                 vfs_unlock_two_folios(src_folio, dst_folio);
 250                 folio_put(dst_folio);
 251                 folio_put(src_folio);
 252
 253                 if (!same)
 254                         break;
 255
 256                 srcoff += cmp_len;
 257                 dstoff += cmp_len;
 258                 len -= cmp_len;
 259         }
 260
 261         *is_same = same;
 262         return 0;
 263
 264 out_error:
 265         return error;
 266 }
 267
 268 /*
 269  * Check that the two inodes are eligible for cloning, the ranges make
 270  * sense, and then flush all dirty data.  Caller must ensure that the
 271  * inodes have been locked against any other modifications.
 272  *
 273  * If there's an error, then the usual negative error code is returned.
 274  * Otherwise returns 0 with *len set to the request length.
 275  */
 276 int
 277 __generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
 278                                 struct file *file_out, loff_t pos_out,
 279                                 loff_t *len, unsigned int remap_flags,
 280                                 const struct iomap_ops *dax_read_ops)
 281 {
 282         struct inode *inode_in = file_inode(file_in);
 283         struct inode *inode_out = file_inode(file_out);
 284         bool same_inode = (inode_in == inode_out);
 285         int ret;
 286
 287         /* Don't touch certain kinds of inodes */
 288         if (IS_IMMUTABLE(inode_out))
 289                 return -EPERM;
 290
 291         if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
 292                 return -ETXTBSY;
 293
 294         /* Don't reflink dirs, pipes, sockets... */
 295         if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
 296                 return -EISDIR;
 297         if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
 298                 return -EINVAL;
 299
 300         /* Zero length dedupe exits immediately; reflink goes to EOF. */
 301         if (*len == 0) {
 302                 loff_t isize = i_size_read(inode_in);
 303
 304                 if ((remap_flags & REMAP_FILE_DEDUP) || pos_in == isize)
 305                         return 0;
 306                 if (pos_in > isize)
 307                         return -EINVAL;
 308                 *len = isize - pos_in;
 309                 if (*len == 0)
 310                         return 0;
 311         }
 312
 313         /* Check that we don't violate system file offset limits. */
 314         ret = generic_remap_checks(file_in, pos_in, file_out, pos_out, len,
 315                         remap_flags);
 316         if (ret || *len == 0)
 317                 return ret;
 318
 319         /* Wait for the completion of any pending IOs on both files */
 320         inode_dio_wait(inode_in);
 321         if (!same_inode)
 322                 inode_dio_wait(inode_out);
 323
 324         ret = filemap_write_and_wait_range(inode_in->i_mapping,
 325                         pos_in, pos_in + *len - 1);
 326         if (ret)
 327                 return ret;
 328
 329         ret = filemap_write_and_wait_range(inode_out->i_mapping,
 330                         pos_out, pos_out + *len - 1);
 331         if (ret)
 332                 return ret;
 333
 334         /*
 335          * Check that the extents are the same.
 336          */
 337         if (remap_flags & REMAP_FILE_DEDUP) {
 338                 bool            is_same = false;
 339
 340                 if (!IS_DAX(inode_in))
 341                         ret = vfs_dedupe_file_range_compare(file_in, pos_in,
 342                                         file_out, pos_out, *len, &is_same);
 343                 else if (dax_read_ops)
 344                         ret = dax_dedupe_file_range_compare(inode_in, pos_in,
 345                                         inode_out, pos_out, *len, &is_same,
 346                                         dax_read_ops);
 347                 else
 348                         return -EINVAL;
 349                 if (ret)
 350                         return ret;
 351                 if (!is_same)
 352                         return -EBADE;
 353         }
 354
 355         ret = generic_remap_check_len(inode_in, inode_out, pos_out, len,
 356                         remap_flags);
 357         if (ret || *len == 0)
 358                 return ret;
 359
 360         /* If can't alter the file contents, we're done. */
 361         if (!(remap_flags & REMAP_FILE_DEDUP))
 362                 ret = file_modified(file_out);
 363
 364         return ret;
 365 }
 366
 367 int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
 368                                   struct file *file_out, loff_t pos_out,
 369                                   loff_t *len, unsigned int remap_flags)
 370 {
 371         return __generic_remap_file_range_prep(file_in, pos_in, file_out,
 372                                                pos_out, len, remap_flags, NULL);
 373 }
 374 EXPORT_SYMBOL(generic_remap_file_range_prep);
 375
 376 loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
 377                             struct file *file_out, loff_t pos_out,
 378                             loff_t len, unsigned int remap_flags)
 379 {
 380         loff_t ret;
 381
 382         WARN_ON_ONCE(remap_flags & REMAP_FILE_DEDUP);
 383
 384         if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
 385                 return -EXDEV;
 386
 387         ret = generic_file_rw_checks(file_in, file_out);
 388         if (ret < 0)
 389                 return ret;
 390
 391         if (!file_in->f_op->remap_file_range)
 392                 return -EOPNOTSUPP;
 393
 394         ret = remap_verify_area(file_in, pos_in, len, false);
 395         if (ret)
 396                 return ret;
 397
 398         ret = remap_verify_area(file_out, pos_out, len, true);
 399         if (ret)
 400                 return ret;
 401
 402         file_start_write(file_out);
 403         ret = file_in->f_op->remap_file_range(file_in, pos_in,
 404                         file_out, pos_out, len, remap_flags);
 405         file_end_write(file_out);
 406         if (ret < 0)
 407                 return ret;
 408
 409         fsnotify_access(file_in);
 410         fsnotify_modify(file_out);
 411         return ret;
 412 }
 413 EXPORT_SYMBOL(vfs_clone_file_range);
 414
 415 /* Check whether we are allowed to dedupe the destination file */
 416 static bool may_dedupe_file(struct file *file)
 417 {
 418         struct mnt_idmap *idmap = file_mnt_idmap(file);
 419         struct inode *inode = file_inode(file);
 420
 421         if (capable(CAP_SYS_ADMIN))
 422                 return true;
 423         if (file->f_mode & FMODE_WRITE)
 424                 return true;
 425         if (vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode), current_fsuid()))
 426                 return true;
 427         if (!inode_permission(idmap, inode, MAY_WRITE))
 428                 return true;
 429         return false;
 430 }
 431
 432 loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
 433                                  struct file *dst_file, loff_t dst_pos,
 434                                  loff_t len, unsigned int remap_flags)
 435 {
 436         loff_t ret;
 437
 438         WARN_ON_ONCE(remap_flags & ~(REMAP_FILE_DEDUP |
 439                                      REMAP_FILE_CAN_SHORTEN));
 440
 441         /*
 442          * This is redundant if called from vfs_dedupe_file_range(), but other
 443          * callers need it and it's not performance sesitive...
 444          */
 445         ret = remap_verify_area(src_file, src_pos, len, false);
 446         if (ret)
 447                 return ret;
 448
 449         ret = remap_verify_area(dst_file, dst_pos, len, true);
 450         if (ret)
 451                 return ret;
 452
 453         /*
 454          * This needs to be called after remap_verify_area() because of
 455          * sb_start_write() and before may_dedupe_file() because the mount's
 456          * MAY_WRITE need to be checked with mnt_get_write_access_file() held.
 457          */
 458         ret = mnt_want_write_file(dst_file);
 459         if (ret)
 460                 return ret;
 461
 462         ret = -EPERM;
 463         if (!may_dedupe_file(dst_file))
 464                 goto out_drop_write;
 465
 466         ret = -EXDEV;
 467         if (file_inode(src_file)->i_sb != file_inode(dst_file)->i_sb)
 468                 goto out_drop_write;
 469
 470         ret = -EISDIR;
 471         if (S_ISDIR(file_inode(dst_file)->i_mode))
 472                 goto out_drop_write;
 473
 474         ret = -EINVAL;
 475         if (!dst_file->f_op->remap_file_range)
 476                 goto out_drop_write;
 477
 478         if (len == 0) {
 479                 ret = 0;
 480                 goto out_drop_write;
 481         }
 482
 483         ret = dst_file->f_op->remap_file_range(src_file, src_pos, dst_file,
 484                         dst_pos, len, remap_flags | REMAP_FILE_DEDUP);
 485 out_drop_write:
 486         mnt_drop_write_file(dst_file);
 487
 488         return ret;
 489 }
 490 EXPORT_SYMBOL(vfs_dedupe_file_range_one);
 491
 492 int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
 493 {
 494         struct file_dedupe_range_info *info;
 495         struct inode *src = file_inode(file);
 496         u64 off;
 497         u64 len;
 498         int i;
 499         int ret;
 500         u16 count = same->dest_count;
 501         loff_t deduped;
 502
 503         if (!(file->f_mode & FMODE_READ))
 504                 return -EINVAL;
 505
 506         if (same->reserved1 || same->reserved2)
 507                 return -EINVAL;
 508
 509         off = same->src_offset;
 510         len = same->src_length;
 511
 512         if (S_ISDIR(src->i_mode))
 513                 return -EISDIR;
 514
 515         if (!S_ISREG(src->i_mode))
 516                 return -EINVAL;
 517
 518         if (!file->f_op->remap_file_range)
 519                 return -EOPNOTSUPP;
 520
 521         ret = remap_verify_area(file, off, len, false);
 522         if (ret < 0)
 523                 return ret;
 524         ret = 0;
 525
 526         if (off + len > i_size_read(src))
 527                 return -EINVAL;
 528
 529         /* Arbitrary 1G limit on a single dedupe request, can be raised. */
 530         len = min_t(u64, len, 1 << 30);
 531
 532         /* pre-format output fields to sane values */
 533         for (i = 0; i < count; i++) {
 534                 same->info[i].bytes_deduped = 0ULL;
 535                 same->info[i].status = FILE_DEDUPE_RANGE_SAME;
 536         }
 537
 538         for (i = 0, info = same->info; i < count; i++, info++) {
 539                 CLASS(fd, dst_fd)(info->dest_fd);
 540
 541                 if (fd_empty(dst_fd)) {
 542                         info->status = -EBADF;
 543                         goto next_loop;
 544                 }
 545
 546                 if (info->reserved) {
 547                         info->status = -EINVAL;
 548                         goto next_loop;
 549                 }
 550
 551                 deduped = vfs_dedupe_file_range_one(file, off, fd_file(dst_fd),
 552                                                     info->dest_offset, len,
 553                                                     REMAP_FILE_CAN_SHORTEN);
 554                 if (deduped == -EBADE)
 555                         info->status = FILE_DEDUPE_RANGE_DIFFERS;
 556                 else if (deduped < 0)
 557                         info->status = deduped;
 558                 else
 559                         info->bytes_deduped = len;
 560
 561 next_loop:
 562                 if (fatal_signal_pending(current))
 563                         break;
 564         }
 565         return ret;
 566 }
 567 EXPORT_SYMBOL(vfs_dedupe_file_range);