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 "internal.h"
  18
  19 #include <linux/uaccess.h>
  20 #include <asm/unistd.h>
  21
  22 /*
  23  * Performs necessary checks before doing a clone.
  24  *
  25  * Can adjust amount of bytes to clone via @req_count argument.
  26  * Returns appropriate error code that caller should return or
  27  * zero in case the clone should be allowed.
  28  */
  29 static int generic_remap_checks(struct file *file_in, loff_t pos_in,
  30                                 struct file *file_out, loff_t pos_out,
  31                                 loff_t *req_count, unsigned int remap_flags)
  32 {
  33         struct inode *inode_in = file_in->f_mapping->host;
  34         struct inode *inode_out = file_out->f_mapping->host;
  35         uint64_t count = *req_count;
  36         uint64_t bcount;
  37         loff_t size_in, size_out;
  38         loff_t bs = inode_out->i_sb->s_blocksize;
  39         int ret;
  40
  41         /* The start of both ranges must be aligned to an fs block. */
  42         if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_out, bs))
  43                 return -EINVAL;
  44
  45         /* Ensure offsets don't wrap. */
  46         if (pos_in + count < pos_in || pos_out + count < pos_out)
  47                 return -EINVAL;
  48
  49         size_in = i_size_read(inode_in);
  50         size_out = i_size_read(inode_out);
  51
  52         /* Dedupe requires both ranges to be within EOF. */
  53         if ((remap_flags & REMAP_FILE_DEDUP) &&
  54             (pos_in >= size_in || pos_in + count > size_in ||
  55              pos_out >= size_out || pos_out + count > size_out))
  56                 return -EINVAL;
  57
  58         /* Ensure the infile range is within the infile. */
  59         if (pos_in >= size_in)
  60                 return -EINVAL;
  61         count = min(count, size_in - (uint64_t)pos_in);
  62
  63         ret = generic_write_check_limits(file_out, pos_out, &count);
  64         if (ret)
  65                 return ret;
  66
  67         /*
  68          * If the user wanted us to link to the infile's EOF, round up to the
  69          * next block boundary for this check.
  70          *
  71          * Otherwise, make sure the count is also block-aligned, having
  72          * already confirmed the starting offsets' block alignment.
  73          */
  74         if (pos_in + count == size_in) {
  75                 bcount = ALIGN(size_in, bs) - pos_in;
  76         } else {
  77                 if (!IS_ALIGNED(count, bs))
  78                         count = ALIGN_DOWN(count, bs);
  79                 bcount = count;
  80         }
  81
  82         /* Don't allow overlapped cloning within the same file. */
  83         if (inode_in == inode_out &&
  84             pos_out + bcount > pos_in &&
  85             pos_out < pos_in + bcount)
  86                 return -EINVAL;
  87
  88         /*
  89          * We shortened the request but the caller can't deal with that, so
  90          * bounce the request back to userspace.
  91          */
  92         if (*req_count != count && !(remap_flags & REMAP_FILE_CAN_SHORTEN))
  93                 return -EINVAL;
  94
  95         *req_count = count;
  96         return 0;
  97 }
  98
  99 static int remap_verify_area(struct file *file, loff_t pos, loff_t len,
 100                              bool write)
 101 {
 102         struct inode *inode = file_inode(file);
 103
 104         if (unlikely(pos < 0 || len < 0))
 105                 return -EINVAL;
 106
 107         if (unlikely((loff_t) (pos + len) < 0))
 108                 return -EINVAL;
 109
 110         if (unlikely(inode->i_flctx && mandatory_lock(inode))) {
 111                 loff_t end = len ? pos + len - 1 : OFFSET_MAX;
 112                 int retval;
 113
 114                 retval = locks_mandatory_area(inode, file, pos, end,
 115                                 write ? F_WRLCK : F_RDLCK);
 116                 if (retval < 0)
 117                         return retval;
 118         }
 119
 120         return security_file_permission(file, write ? MAY_WRITE : MAY_READ);
 121 }
 122
 123 /*
 124  * Ensure that we don't remap a partial EOF block in the middle of something
 125  * else.  Assume that the offsets have already been checked for block
 126  * alignment.
 127  *
 128  * For clone we only link a partial EOF block above or at the destination file's
 129  * EOF.  For deduplication we accept a partial EOF block only if it ends at the
 130  * destination file's EOF (can not link it into the middle of a file).
 131  *
 132  * Shorten the request if possible.
 133  */
 134 static int generic_remap_check_len(struct inode *inode_in,
 135                                    struct inode *inode_out,
 136                                    loff_t pos_out,
 137                                    loff_t *len,
 138                                    unsigned int remap_flags)
 139 {
 140         u64 blkmask = i_blocksize(inode_in) - 1;
 141         loff_t new_len = *len;
 142
 143         if ((*len & blkmask) == 0)
 144                 return 0;
 145
 146         if (pos_out + *len < i_size_read(inode_out))
 147                 new_len &= ~blkmask;
 148
 149         if (new_len == *len)
 150                 return 0;
 151
 152         if (remap_flags & REMAP_FILE_CAN_SHORTEN) {
 153                 *len = new_len;
 154                 return 0;
 155         }
 156
 157         return (remap_flags & REMAP_FILE_DEDUP) ? -EBADE : -EINVAL;
 158 }
 159
 160 /* Read a page's worth of file data into the page cache. */
 161 static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)
 162 {
 163         struct page *page;
 164
 165         page = read_mapping_page(inode->i_mapping, offset >> PAGE_SHIFT, NULL);
 166         if (IS_ERR(page))
 167                 return page;
 168         if (!PageUptodate(page)) {
 169                 put_page(page);
 170                 return ERR_PTR(-EIO);
 171         }
 172         return page;
 173 }
 174
 175 /*
 176  * Lock two pages, ensuring that we lock in offset order if the pages are from
 177  * the same file.
 178  */
 179 static void vfs_lock_two_pages(struct page *page1, struct page *page2)
 180 {
 181         /* Always lock in order of increasing index. */
 182         if (page1->index > page2->index)
 183                 swap(page1, page2);
 184
 185         lock_page(page1);
 186         if (page1 != page2)
 187                 lock_page(page2);
 188 }
 189
 190 /* Unlock two pages, being careful not to unlock the same page twice. */
 191 static void vfs_unlock_two_pages(struct page *page1, struct page *page2)
 192 {
 193         unlock_page(page1);
 194         if (page1 != page2)
 195                 unlock_page(page2);
 196 }
 197
 198 /*
 199  * Compare extents of two files to see if they are the same.
 200  * Caller must have locked both inodes to prevent write races.
 201  */
 202 static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
 203                                          struct inode *dest, loff_t destoff,
 204                                          loff_t len, bool *is_same)
 205 {
 206         loff_t src_poff;
 207         loff_t dest_poff;
 208         void *src_addr;
 209         void *dest_addr;
 210         struct page *src_page;
 211         struct page *dest_page;
 212         loff_t cmp_len;
 213         bool same;
 214         int error;
 215
 216         error = -EINVAL;
 217         same = true;
 218         while (len) {
 219                 src_poff = srcoff & (PAGE_SIZE - 1);
 220                 dest_poff = destoff & (PAGE_SIZE - 1);
 221                 cmp_len = min(PAGE_SIZE - src_poff,
 222                               PAGE_SIZE - dest_poff);
 223                 cmp_len = min(cmp_len, len);
 224                 if (cmp_len <= 0)
 225                         goto out_error;
 226
 227                 src_page = vfs_dedupe_get_page(src, srcoff);
 228                 if (IS_ERR(src_page)) {
 229                         error = PTR_ERR(src_page);
 230                         goto out_error;
 231                 }
 232                 dest_page = vfs_dedupe_get_page(dest, destoff);
 233                 if (IS_ERR(dest_page)) {
 234                         error = PTR_ERR(dest_page);
 235                         put_page(src_page);
 236                         goto out_error;
 237                 }
 238
 239                 vfs_lock_two_pages(src_page, dest_page);
 240
 241                 /*
 242                  * Now that we've locked both pages, make sure they're still
 243                  * mapped to the file data we're interested in.  If not,
 244                  * someone is invalidating pages on us and we lose.
 245                  */
 246                 if (!PageUptodate(src_page) || !PageUptodate(dest_page) ||
 247                     src_page->mapping != src->i_mapping ||
 248                     dest_page->mapping != dest->i_mapping) {
 249                         same = false;
 250                         goto unlock;
 251                 }
 252
 253                 src_addr = kmap_atomic(src_page);
 254                 dest_addr = kmap_atomic(dest_page);
 255
 256                 flush_dcache_page(src_page);
 257                 flush_dcache_page(dest_page);
 258
 259                 if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len))
 260                         same = false;
 261
 262                 kunmap_atomic(dest_addr);
 263                 kunmap_atomic(src_addr);
 264 unlock:
 265                 vfs_unlock_two_pages(src_page, dest_page);
 266                 put_page(dest_page);
 267                 put_page(src_page);
 268
 269                 if (!same)
 270                         break;
 271
 272                 srcoff += cmp_len;
 273                 destoff += cmp_len;
 274                 len -= cmp_len;
 275         }
 276
 277         *is_same = same;
 278         return 0;
 279
 280 out_error:
 281         return error;
 282 }
 283
 284 /*
 285  * Check that the two inodes are eligible for cloning, the ranges make
 286  * sense, and then flush all dirty data.  Caller must ensure that the
 287  * inodes have been locked against any other modifications.
 288  *
 289  * If there's an error, then the usual negative error code is returned.
 290  * Otherwise returns 0 with *len set to the request length.
 291  */
 292 int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
 293                                   struct file *file_out, loff_t pos_out,
 294                                   loff_t *len, unsigned int remap_flags)
 295 {
 296         struct inode *inode_in = file_inode(file_in);
 297         struct inode *inode_out = file_inode(file_out);
 298         bool same_inode = (inode_in == inode_out);
 299         int ret;
 300
 301         /* Don't touch certain kinds of inodes */
 302         if (IS_IMMUTABLE(inode_out))
 303                 return -EPERM;
 304
 305         if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
 306                 return -ETXTBSY;
 307
 308         /* Don't reflink dirs, pipes, sockets... */
 309         if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
 310                 return -EISDIR;
 311         if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
 312                 return -EINVAL;
 313
 314         /* Zero length dedupe exits immediately; reflink goes to EOF. */
 315         if (*len == 0) {
 316                 loff_t isize = i_size_read(inode_in);
 317
 318                 if ((remap_flags & REMAP_FILE_DEDUP) || pos_in == isize)
 319                         return 0;
 320                 if (pos_in > isize)
 321                         return -EINVAL;
 322                 *len = isize - pos_in;
 323                 if (*len == 0)
 324                         return 0;
 325         }
 326
 327         /* Check that we don't violate system file offset limits. */
 328         ret = generic_remap_checks(file_in, pos_in, file_out, pos_out, len,
 329                         remap_flags);
 330         if (ret)
 331                 return ret;
 332
 333         /* Wait for the completion of any pending IOs on both files */
 334         inode_dio_wait(inode_in);
 335         if (!same_inode)
 336                 inode_dio_wait(inode_out);
 337
 338         ret = filemap_write_and_wait_range(inode_in->i_mapping,
 339                         pos_in, pos_in + *len - 1);
 340         if (ret)
 341                 return ret;
 342
 343         ret = filemap_write_and_wait_range(inode_out->i_mapping,
 344                         pos_out, pos_out + *len - 1);
 345         if (ret)
 346                 return ret;
 347
 348         /*
 349          * Check that the extents are the same.
 350          */
 351         if (remap_flags & REMAP_FILE_DEDUP) {
 352                 bool            is_same = false;
 353
 354                 ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
 355                                 inode_out, pos_out, *len, &is_same);
 356                 if (ret)
 357                         return ret;
 358                 if (!is_same)
 359                         return -EBADE;
 360         }
 361
 362         ret = generic_remap_check_len(inode_in, inode_out, pos_out, len,
 363                         remap_flags);
 364         if (ret)
 365                 return ret;
 366
 367         /* If can't alter the file contents, we're done. */
 368         if (!(remap_flags & REMAP_FILE_DEDUP))
 369                 ret = file_modified(file_out);
 370
 371         return ret;
 372 }
 373 EXPORT_SYMBOL(generic_remap_file_range_prep);
 374
 375 loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
 376                            struct file *file_out, loff_t pos_out,
 377                            loff_t len, unsigned int remap_flags)
 378 {
 379         loff_t ret;
 380
 381         WARN_ON_ONCE(remap_flags & REMAP_FILE_DEDUP);
 382
 383         /*
 384          * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on
 385          * the same mount. Practically, they only need to be on the same file
 386          * system.
 387          */
 388         if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
 389                 return -EXDEV;
 390
 391         ret = generic_file_rw_checks(file_in, file_out);
 392         if (ret < 0)
 393                 return ret;
 394
 395         if (!file_in->f_op->remap_file_range)
 396                 return -EOPNOTSUPP;
 397
 398         ret = remap_verify_area(file_in, pos_in, len, false);
 399         if (ret)
 400                 return ret;
 401
 402         ret = remap_verify_area(file_out, pos_out, len, true);
 403         if (ret)
 404                 return ret;
 405
 406         ret = file_in->f_op->remap_file_range(file_in, pos_in,
 407                         file_out, pos_out, len, remap_flags);
 408         if (ret < 0)
 409                 return ret;
 410
 411         fsnotify_access(file_in);
 412         fsnotify_modify(file_out);
 413         return ret;
 414 }
 415 EXPORT_SYMBOL(do_clone_file_range);
 416
 417 loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
 418                             struct file *file_out, loff_t pos_out,
 419                             loff_t len, unsigned int remap_flags)
 420 {
 421         loff_t ret;
 422
 423         file_start_write(file_out);
 424         ret = do_clone_file_range(file_in, pos_in, file_out, pos_out, len,
 425                                   remap_flags);
 426         file_end_write(file_out);
 427
 428         return ret;
 429 }
 430 EXPORT_SYMBOL(vfs_clone_file_range);
 431
 432 /* Check whether we are allowed to dedupe the destination file */
 433 static bool allow_file_dedupe(struct file *file)
 434 {
 435         if (capable(CAP_SYS_ADMIN))
 436                 return true;
 437         if (file->f_mode & FMODE_WRITE)
 438                 return true;
 439         if (uid_eq(current_fsuid(), file_inode(file)->i_uid))
 440                 return true;
 441         if (!inode_permission(file_inode(file), MAY_WRITE))
 442                 return true;
 443         return false;
 444 }
 445
 446 loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
 447                                  struct file *dst_file, loff_t dst_pos,
 448                                  loff_t len, unsigned int remap_flags)
 449 {
 450         loff_t ret;
 451
 452         WARN_ON_ONCE(remap_flags & ~(REMAP_FILE_DEDUP |
 453                                      REMAP_FILE_CAN_SHORTEN));
 454
 455         ret = mnt_want_write_file(dst_file);
 456         if (ret)
 457                 return ret;
 458
 459         /*
 460          * This is redundant if called from vfs_dedupe_file_range(), but other
 461          * callers need it and it's not performance sesitive...
 462          */
 463         ret = remap_verify_area(src_file, src_pos, len, false);
 464         if (ret)
 465                 goto out_drop_write;
 466
 467         ret = remap_verify_area(dst_file, dst_pos, len, true);
 468         if (ret)
 469                 goto out_drop_write;
 470
 471         ret = -EPERM;
 472         if (!allow_file_dedupe(dst_file))
 473                 goto out_drop_write;
 474
 475         ret = -EXDEV;
 476         if (src_file->f_path.mnt != dst_file->f_path.mnt)
 477                 goto out_drop_write;
 478
 479         ret = -EISDIR;
 480         if (S_ISDIR(file_inode(dst_file)->i_mode))
 481                 goto out_drop_write;
 482
 483         ret = -EINVAL;
 484         if (!dst_file->f_op->remap_file_range)
 485                 goto out_drop_write;
 486
 487         if (len == 0) {
 488                 ret = 0;
 489                 goto out_drop_write;
 490         }
 491
 492         ret = dst_file->f_op->remap_file_range(src_file, src_pos, dst_file,
 493                         dst_pos, len, remap_flags | REMAP_FILE_DEDUP);
 494 out_drop_write:
 495         mnt_drop_write_file(dst_file);
 496
 497         return ret;
 498 }
 499 EXPORT_SYMBOL(vfs_dedupe_file_range_one);
 500
 501 int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
 502 {
 503         struct file_dedupe_range_info *info;
 504         struct inode *src = file_inode(file);
 505         u64 off;
 506         u64 len;
 507         int i;
 508         int ret;
 509         u16 count = same->dest_count;
 510         loff_t deduped;
 511
 512         if (!(file->f_mode & FMODE_READ))
 513                 return -EINVAL;
 514
 515         if (same->reserved1 || same->reserved2)
 516                 return -EINVAL;
 517
 518         off = same->src_offset;
 519         len = same->src_length;
 520
 521         if (S_ISDIR(src->i_mode))
 522                 return -EISDIR;
 523
 524         if (!S_ISREG(src->i_mode))
 525                 return -EINVAL;
 526
 527         if (!file->f_op->remap_file_range)
 528                 return -EOPNOTSUPP;
 529
 530         ret = remap_verify_area(file, off, len, false);
 531         if (ret < 0)
 532                 return ret;
 533         ret = 0;
 534
 535         if (off + len > i_size_read(src))
 536                 return -EINVAL;
 537
 538         /* Arbitrary 1G limit on a single dedupe request, can be raised. */
 539         len = min_t(u64, len, 1 << 30);
 540
 541         /* pre-format output fields to sane values */
 542         for (i = 0; i < count; i++) {
 543                 same->info[i].bytes_deduped = 0ULL;
 544                 same->info[i].status = FILE_DEDUPE_RANGE_SAME;
 545         }
 546
 547         for (i = 0, info = same->info; i < count; i++, info++) {
 548                 struct fd dst_fd = fdget(info->dest_fd);
 549                 struct file *dst_file = dst_fd.file;
 550
 551                 if (!dst_file) {
 552                         info->status = -EBADF;
 553                         goto next_loop;
 554                 }
 555
 556                 if (info->reserved) {
 557                         info->status = -EINVAL;
 558                         goto next_fdput;
 559                 }
 560
 561                 deduped = vfs_dedupe_file_range_one(file, off, dst_file,
 562                                                     info->dest_offset, len,
 563                                                     REMAP_FILE_CAN_SHORTEN);
 564                 if (deduped == -EBADE)
 565                         info->status = FILE_DEDUPE_RANGE_DIFFERS;
 566                 else if (deduped < 0)
 567                         info->status = deduped;
 568                 else
 569                         info->bytes_deduped = len;
 570
 571 next_fdput:
 572                 fdput(dst_fd);
 573 next_loop:
 574                 if (fatal_signal_pending(current))
 575                         break;
 576         }
 577         return ret;
 578 }
 579 EXPORT_SYMBOL(vfs_dedupe_file_range);