571 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2#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 or29 * zero in case the clone should be allowed.30 */31static 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 the71 * next block boundary for this check.72 *73 * Otherwise, make sure the count is also block-aligned, having74 * 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, so93 * 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 102int 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}120EXPORT_SYMBOL_GPL(remap_verify_area);121 122/*123 * Ensure that we don't remap a partial EOF block in the middle of something124 * else. Assume that the offsets have already been checked for block125 * alignment.126 *127 * For clone we only link a partial EOF block above or at the destination file's128 * EOF. For deduplication we accept a partial EOF block only if it ends at the129 * destination file's EOF (can not link it into the middle of a file).130 *131 * Shorten the request if possible.132 */133static 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. */160static HWJS_SUSPENDS 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 folios167 * are from the same file.168 */169static HWJS_SUSPENDS 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. */181static 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 */192static HWJS_SUSPENDS 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 still225 * 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);248unlock: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 264out_error:265 return error;266}267 268/*269 * Check that the two inodes are eligible for cloning, the ranges make270 * sense, and then flush all dirty data. Caller must ensure that the271 * 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 */276int277__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 else348 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 367int 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}374EXPORT_SYMBOL(generic_remap_file_range_prep);375 376loff_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}413EXPORT_SYMBOL(vfs_clone_file_range);414 415/* Check whether we are allowed to dedupe the destination file */416static HWJS_SUSPENDS 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 432loff_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 other443 * 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 of455 * sb_start_write() and before may_dedupe_file() because the mount's456 * 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);485out_drop_write:486 mnt_drop_write_file(dst_file);487 488 return ret;489}490EXPORT_SYMBOL(vfs_dedupe_file_range_one);491 492int 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 struct fd dst_fd = fdget(info->dest_fd);540 struct file *dst_file = fd_file(dst_fd);541 542 if (!dst_file) {543 info->status = -EBADF;544 goto next_loop;545 }546 547 if (info->reserved) {548 info->status = -EINVAL;549 goto next_fdput;550 }551 552 deduped = vfs_dedupe_file_range_one(file, off, dst_file,553 info->dest_offset, len,554 REMAP_FILE_CAN_SHORTEN);555 if (deduped == -EBADE)556 info->status = FILE_DEDUPE_RANGE_DIFFERS;557 else if (deduped < 0)558 info->status = deduped;559 else560 info->bytes_deduped = len;561 562next_fdput:563 fdput(dst_fd);564next_loop:565 if (fatal_signal_pending(current))566 break;567 }568 return ret;569}570EXPORT_SYMBOL(vfs_dedupe_file_range);571