1 /* 2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) 3 * Licensed under the GPL 4 * 5 * Ported the filesystem routines to 2.5. 6 * 2003-02-10 Petr Baudis <pasky@ucw.cz> 7 */ 8 9 #include <linux/fs.h> 10 #include <linux/magic.h> 11 #include <linux/module.h> 12 #include <linux/mm.h> 13 #include <linux/pagemap.h> 14 #include <linux/statfs.h> 15 #include <linux/slab.h> 16 #include <linux/seq_file.h> 17 #include <linux/writeback.h> 18 #include <linux/mount.h> 19 #include <linux/namei.h> 20 #include "hostfs.h" 21 #include <init.h> 22 #include <kern.h> 23 24 struct hostfs_inode_info { 25 int fd; 26 fmode_t mode; 27 struct inode vfs_inode; 28 struct mutex open_mutex; 29 dev_t dev; 30 struct hostfs_timespec btime; 31 }; 32 33 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode) 34 { 35 return list_entry(inode, struct hostfs_inode_info, vfs_inode); 36 } 37 38 #define FILE_HOSTFS_I(file) HOSTFS_I(file_inode(file)) 39 40 static struct kmem_cache *hostfs_inode_cache; 41 42 /* Changed in hostfs_args before the kernel starts running */ 43 static char *root_ino = ""; 44 static int append = 0; 45 46 static const struct inode_operations hostfs_iops; 47 static const struct inode_operations hostfs_dir_iops; 48 static const struct inode_operations hostfs_link_iops; 49 50 #ifndef MODULE 51 static int __init hostfs_args(char *options, int *add) 52 { 53 char *ptr; 54 55 ptr = strchr(options, ','); 56 if (ptr != NULL) 57 *ptr++ = '\0'; 58 if (*options != '\0') 59 root_ino = options; 60 61 options = ptr; 62 while (options) { 63 ptr = strchr(options, ','); 64 if (ptr != NULL) 65 *ptr++ = '\0'; 66 if (*options != '\0') { 67 if (!strcmp(options, "append")) 68 append = 1; 69 else printf("hostfs_args - unsupported option - %s\n", 70 options); 71 } 72 options = ptr; 73 } 74 return 0; 75 } 76 77 __uml_setup("hostfs=", hostfs_args, 78 "hostfs=<root dir>,<flags>,...\n" 79 " This is used to set hostfs parameters. The root directory argument\n" 80 " is used to confine all hostfs mounts to within the specified directory\n" 81 " tree on the host. If this isn't specified, then a user inside UML can\n" 82 " mount anything on the host that's accessible to the user that's running\n" 83 " it.\n" 84 " The only flag currently supported is 'append', which specifies that all\n" 85 " files opened by hostfs will be opened in append mode.\n\n" 86 ); 87 #endif 88 89 static char *__dentry_name(struct dentry *dentry, char *name) 90 { 91 char *p = dentry_path_raw(dentry, name, PATH_MAX); 92 char *root; 93 size_t len; 94 95 root = dentry->d_sb->s_fs_info; 96 len = strlen(root); 97 if (IS_ERR(p)) { 98 __putname(name); 99 return NULL; 100 } 101 102 /* 103 * This function relies on the fact that dentry_path_raw() will place 104 * the path name at the end of the provided buffer. 105 */ 106 BUG_ON(p + strlen(p) + 1 != name + PATH_MAX); 107 108 strscpy(name, root, PATH_MAX); 109 if (len > p - name) { 110 __putname(name); 111 return NULL; 112 } 113 114 if (p > name + len) 115 strcpy(name + len, p); 116 117 return name; 118 } 119 120 static char *dentry_name(struct dentry *dentry) 121 { 122 char *name = __getname(); 123 if (!name) 124 return NULL; 125 126 return __dentry_name(dentry, name); 127 } 128 129 static char *inode_name(struct inode *ino) 130 { 131 struct dentry *dentry; 132 char *name; 133 134 dentry = d_find_alias(ino); 135 if (!dentry) 136 return NULL; 137 138 name = dentry_name(dentry); 139 140 dput(dentry); 141 142 return name; 143 } 144 145 static char *follow_link(char *link) 146 { 147 char *name, *resolved, *end; 148 int n; 149 150 name = kmalloc(PATH_MAX, GFP_KERNEL); 151 if (!name) { 152 n = -ENOMEM; 153 goto out_free; 154 } 155 156 n = hostfs_do_readlink(link, name, PATH_MAX); 157 if (n < 0) 158 goto out_free; 159 else if (n == PATH_MAX) { 160 n = -E2BIG; 161 goto out_free; 162 } 163 164 if (*name == '/') 165 return name; 166 167 end = strrchr(link, '/'); 168 if (end == NULL) 169 return name; 170 171 *(end + 1) = '\0'; 172 173 resolved = kasprintf(GFP_KERNEL, "%s%s", link, name); 174 if (resolved == NULL) { 175 n = -ENOMEM; 176 goto out_free; 177 } 178 179 kfree(name); 180 return resolved; 181 182 out_free: 183 kfree(name); 184 return ERR_PTR(n); 185 } 186 187 static int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf) 188 { 189 /* 190 * do_statfs uses struct statfs64 internally, but the linux kernel 191 * struct statfs still has 32-bit versions for most of these fields, 192 * so we convert them here 193 */ 194 int err; 195 long long f_blocks; 196 long long f_bfree; 197 long long f_bavail; 198 long long f_files; 199 long long f_ffree; 200 201 err = do_statfs(dentry->d_sb->s_fs_info, 202 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files, 203 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid), 204 &sf->f_namelen); 205 if (err) 206 return err; 207 sf->f_blocks = f_blocks; 208 sf->f_bfree = f_bfree; 209 sf->f_bavail = f_bavail; 210 sf->f_files = f_files; 211 sf->f_ffree = f_ffree; 212 sf->f_type = HOSTFS_SUPER_MAGIC; 213 return 0; 214 } 215 216 static struct inode *hostfs_alloc_inode(struct super_block *sb) 217 { 218 struct hostfs_inode_info *hi; 219 220 hi = alloc_inode_sb(sb, hostfs_inode_cache, GFP_KERNEL_ACCOUNT); 221 if (hi == NULL) 222 return NULL; 223 hi->fd = -1; 224 hi->mode = 0; 225 hi->dev = 0; 226 inode_init_once(&hi->vfs_inode); 227 mutex_init(&hi->open_mutex); 228 return &hi->vfs_inode; 229 } 230 231 static void hostfs_evict_inode(struct inode *inode) 232 { 233 truncate_inode_pages_final(&inode->i_data); 234 clear_inode(inode); 235 if (HOSTFS_I(inode)->fd != -1) { 236 close_file(&HOSTFS_I(inode)->fd); 237 HOSTFS_I(inode)->fd = -1; 238 HOSTFS_I(inode)->dev = 0; 239 } 240 } 241 242 static void hostfs_free_inode(struct inode *inode) 243 { 244 kmem_cache_free(hostfs_inode_cache, HOSTFS_I(inode)); 245 } 246 247 static int hostfs_show_options(struct seq_file *seq, struct dentry *root) 248 { 249 const char *root_path = root->d_sb->s_fs_info; 250 size_t offset = strlen(root_ino) + 1; 251 252 if (strlen(root_path) > offset) 253 seq_show_option(seq, root_path + offset, NULL); 254 255 if (append) 256 seq_puts(seq, ",append"); 257 258 return 0; 259 } 260 261 static const struct super_operations hostfs_sbops = { 262 .alloc_inode = hostfs_alloc_inode, 263 .free_inode = hostfs_free_inode, 264 .drop_inode = generic_delete_inode, 265 .evict_inode = hostfs_evict_inode, 266 .statfs = hostfs_statfs, 267 .show_options = hostfs_show_options, 268 }; 269 270 static int hostfs_readdir(struct file *file, struct dir_context *ctx) 271 { 272 void *dir; 273 char *name; 274 unsigned long long next, ino; 275 int error, len; 276 unsigned int type; 277 278 name = dentry_name(file->f_path.dentry); 279 if (name == NULL) 280 return -ENOMEM; 281 dir = open_dir(name, &error); 282 __putname(name); 283 if (dir == NULL) 284 return -error; 285 next = ctx->pos; 286 seek_dir(dir, next); 287 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) { 288 if (!dir_emit(ctx, name, len, ino, type)) 289 break; 290 ctx->pos = next; 291 } 292 close_dir(dir); 293 return 0; 294 } 295 296 static int hostfs_open(struct inode *ino, struct file *file) 297 { 298 char *name; 299 fmode_t mode; 300 int err; 301 int r, w, fd; 302 303 mode = file->f_mode & (FMODE_READ | FMODE_WRITE); 304 if ((mode & HOSTFS_I(ino)->mode) == mode) 305 return 0; 306 307 mode |= HOSTFS_I(ino)->mode; 308 309 retry: 310 r = w = 0; 311 312 if (mode & FMODE_READ) 313 r = 1; 314 if (mode & FMODE_WRITE) 315 r = w = 1; 316 317 name = dentry_name(file_dentry(file)); 318 if (name == NULL) 319 return -ENOMEM; 320 321 fd = open_file(name, r, w, append); 322 __putname(name); 323 if (fd < 0) 324 return fd; 325 326 mutex_lock(&HOSTFS_I(ino)->open_mutex); 327 /* somebody else had handled it first? */ 328 if ((mode & HOSTFS_I(ino)->mode) == mode) { 329 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 330 close_file(&fd); 331 return 0; 332 } 333 if ((mode | HOSTFS_I(ino)->mode) != mode) { 334 mode |= HOSTFS_I(ino)->mode; 335 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 336 close_file(&fd); 337 goto retry; 338 } 339 if (HOSTFS_I(ino)->fd == -1) { 340 HOSTFS_I(ino)->fd = fd; 341 } else { 342 err = replace_file(fd, HOSTFS_I(ino)->fd); 343 close_file(&fd); 344 if (err < 0) { 345 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 346 return err; 347 } 348 } 349 HOSTFS_I(ino)->mode = mode; 350 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 351 352 return 0; 353 } 354 355 static int hostfs_file_release(struct inode *inode, struct file *file) 356 { 357 filemap_write_and_wait(inode->i_mapping); 358 359 return 0; 360 } 361 362 static int hostfs_fsync(struct file *file, loff_t start, loff_t end, 363 int datasync) 364 { 365 struct inode *inode = file->f_mapping->host; 366 int ret; 367 368 ret = file_write_and_wait_range(file, start, end); 369 if (ret) 370 return ret; 371 372 inode_lock(inode); 373 ret = fsync_file(HOSTFS_I(inode)->fd, datasync); 374 inode_unlock(inode); 375 376 return ret; 377 } 378 379 static const struct file_operations hostfs_file_fops = { 380 .llseek = generic_file_llseek, 381 .splice_read = filemap_splice_read, 382 .splice_write = iter_file_splice_write, 383 .read_iter = generic_file_read_iter, 384 .write_iter = generic_file_write_iter, 385 .mmap = generic_file_mmap, 386 .open = hostfs_open, 387 .release = hostfs_file_release, 388 .fsync = hostfs_fsync, 389 }; 390 391 static const struct file_operations hostfs_dir_fops = { 392 .llseek = generic_file_llseek, 393 .iterate_shared = hostfs_readdir, 394 .read = generic_read_dir, 395 .open = hostfs_open, 396 .fsync = hostfs_fsync, 397 }; 398 399 static int hostfs_writepage(struct page *page, struct writeback_control *wbc) 400 { 401 struct address_space *mapping = page->mapping; 402 struct inode *inode = mapping->host; 403 char *buffer; 404 loff_t base = page_offset(page); 405 int count = PAGE_SIZE; 406 int end_index = inode->i_size >> PAGE_SHIFT; 407 int err; 408 409 if (page->index >= end_index) 410 count = inode->i_size & (PAGE_SIZE-1); 411 412 buffer = kmap_local_page(page); 413 414 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count); 415 if (err != count) { 416 if (err >= 0) 417 err = -EIO; 418 mapping_set_error(mapping, err); 419 goto out; 420 } 421 422 if (base > inode->i_size) 423 inode->i_size = base; 424 425 err = 0; 426 427 out: 428 kunmap_local(buffer); 429 unlock_page(page); 430 431 return err; 432 } 433 434 static int hostfs_read_folio(struct file *file, struct folio *folio) 435 { 436 struct page *page = &folio->page; 437 char *buffer; 438 loff_t start = page_offset(page); 439 int bytes_read, ret = 0; 440 441 buffer = kmap_local_page(page); 442 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, 443 PAGE_SIZE); 444 if (bytes_read < 0) { 445 ClearPageUptodate(page); 446 SetPageError(page); 447 ret = bytes_read; 448 goto out; 449 } 450 451 memset(buffer + bytes_read, 0, PAGE_SIZE - bytes_read); 452 453 ClearPageError(page); 454 SetPageUptodate(page); 455 456 out: 457 flush_dcache_page(page); 458 kunmap_local(buffer); 459 unlock_page(page); 460 461 return ret; 462 } 463 464 static int hostfs_write_begin(struct file *file, struct address_space *mapping, 465 loff_t pos, unsigned len, 466 struct page **pagep, void **fsdata) 467 { 468 pgoff_t index = pos >> PAGE_SHIFT; 469 470 *pagep = grab_cache_page_write_begin(mapping, index); 471 if (!*pagep) 472 return -ENOMEM; 473 return 0; 474 } 475 476 static int hostfs_write_end(struct file *file, struct address_space *mapping, 477 loff_t pos, unsigned len, unsigned copied, 478 struct page *page, void *fsdata) 479 { 480 struct inode *inode = mapping->host; 481 void *buffer; 482 unsigned from = pos & (PAGE_SIZE - 1); 483 int err; 484 485 buffer = kmap_local_page(page); 486 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); 487 kunmap_local(buffer); 488 489 if (!PageUptodate(page) && err == PAGE_SIZE) 490 SetPageUptodate(page); 491 492 /* 493 * If err > 0, write_file has added err to pos, so we are comparing 494 * i_size against the last byte written. 495 */ 496 if (err > 0 && (pos > inode->i_size)) 497 inode->i_size = pos; 498 unlock_page(page); 499 put_page(page); 500 501 return err; 502 } 503 504 static const struct address_space_operations hostfs_aops = { 505 .writepage = hostfs_writepage, 506 .read_folio = hostfs_read_folio, 507 .dirty_folio = filemap_dirty_folio, 508 .write_begin = hostfs_write_begin, 509 .write_end = hostfs_write_end, 510 }; 511 512 static int hostfs_inode_update(struct inode *ino, const struct hostfs_stat *st) 513 { 514 set_nlink(ino, st->nlink); 515 i_uid_write(ino, st->uid); 516 i_gid_write(ino, st->gid); 517 ino->i_atime = 518 (struct timespec64){ st->atime.tv_sec, st->atime.tv_nsec }; 519 ino->i_mtime = 520 (struct timespec64){ st->mtime.tv_sec, st->mtime.tv_nsec }; 521 inode_set_ctime(ino, st->ctime.tv_sec, st->ctime.tv_nsec); 522 ino->i_size = st->size; 523 ino->i_blocks = st->blocks; 524 return 0; 525 } 526 527 static int hostfs_inode_set(struct inode *ino, void *data) 528 { 529 struct hostfs_stat *st = data; 530 dev_t dev, rdev; 531 532 /* Reencode maj and min with the kernel encoding.*/ 533 rdev = MKDEV(st->rdev.maj, st->rdev.min); 534 dev = MKDEV(st->dev.maj, st->dev.min); 535 536 switch (st->mode & S_IFMT) { 537 case S_IFLNK: 538 ino->i_op = &hostfs_link_iops; 539 break; 540 case S_IFDIR: 541 ino->i_op = &hostfs_dir_iops; 542 ino->i_fop = &hostfs_dir_fops; 543 break; 544 case S_IFCHR: 545 case S_IFBLK: 546 case S_IFIFO: 547 case S_IFSOCK: 548 init_special_inode(ino, st->mode & S_IFMT, rdev); 549 ino->i_op = &hostfs_iops; 550 break; 551 case S_IFREG: 552 ino->i_op = &hostfs_iops; 553 ino->i_fop = &hostfs_file_fops; 554 ino->i_mapping->a_ops = &hostfs_aops; 555 break; 556 default: 557 return -EIO; 558 } 559 560 HOSTFS_I(ino)->dev = dev; 561 HOSTFS_I(ino)->btime = st->btime; 562 ino->i_ino = st->ino; 563 ino->i_mode = st->mode; 564 return hostfs_inode_update(ino, st); 565 } 566 567 static int hostfs_inode_test(struct inode *inode, void *data) 568 { 569 const struct hostfs_stat *st = data; 570 dev_t dev = MKDEV(st->dev.maj, st->dev.min); 571 572 return inode->i_ino == st->ino && HOSTFS_I(inode)->dev == dev && 573 (inode->i_mode & S_IFMT) == (st->mode & S_IFMT) && 574 HOSTFS_I(inode)->btime.tv_sec == st->btime.tv_sec && 575 HOSTFS_I(inode)->btime.tv_nsec == st->btime.tv_nsec; 576 } 577 578 static struct inode *hostfs_iget(struct super_block *sb, char *name) 579 { 580 struct inode *inode; 581 struct hostfs_stat st; 582 int err = stat_file(name, &st, -1); 583 584 if (err) 585 return ERR_PTR(err); 586 587 inode = iget5_locked(sb, st.ino, hostfs_inode_test, hostfs_inode_set, 588 &st); 589 if (!inode) 590 return ERR_PTR(-ENOMEM); 591 592 if (inode->i_state & I_NEW) { 593 unlock_new_inode(inode); 594 } else { 595 spin_lock(&inode->i_lock); 596 hostfs_inode_update(inode, &st); 597 spin_unlock(&inode->i_lock); 598 } 599 600 return inode; 601 } 602 603 static int hostfs_create(struct mnt_idmap *idmap, struct inode *dir, 604 struct dentry *dentry, umode_t mode, bool excl) 605 { 606 struct inode *inode; 607 char *name; 608 int fd; 609 610 name = dentry_name(dentry); 611 if (name == NULL) 612 return -ENOMEM; 613 614 fd = file_create(name, mode & 0777); 615 if (fd < 0) { 616 __putname(name); 617 return fd; 618 } 619 620 inode = hostfs_iget(dir->i_sb, name); 621 __putname(name); 622 if (IS_ERR(inode)) 623 return PTR_ERR(inode); 624 625 HOSTFS_I(inode)->fd = fd; 626 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; 627 d_instantiate(dentry, inode); 628 return 0; 629 } 630 631 static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, 632 unsigned int flags) 633 { 634 struct inode *inode = NULL; 635 char *name; 636 637 name = dentry_name(dentry); 638 if (name == NULL) 639 return ERR_PTR(-ENOMEM); 640 641 inode = hostfs_iget(ino->i_sb, name); 642 __putname(name); 643 if (IS_ERR(inode)) { 644 if (PTR_ERR(inode) == -ENOENT) 645 inode = NULL; 646 else 647 return ERR_CAST(inode); 648 } 649 650 return d_splice_alias(inode, dentry); 651 } 652 653 static int hostfs_link(struct dentry *to, struct inode *ino, 654 struct dentry *from) 655 { 656 char *from_name, *to_name; 657 int err; 658 659 if ((from_name = dentry_name(from)) == NULL) 660 return -ENOMEM; 661 to_name = dentry_name(to); 662 if (to_name == NULL) { 663 __putname(from_name); 664 return -ENOMEM; 665 } 666 err = link_file(to_name, from_name); 667 __putname(from_name); 668 __putname(to_name); 669 return err; 670 } 671 672 static int hostfs_unlink(struct inode *ino, struct dentry *dentry) 673 { 674 char *file; 675 int err; 676 677 if (append) 678 return -EPERM; 679 680 if ((file = dentry_name(dentry)) == NULL) 681 return -ENOMEM; 682 683 err = unlink_file(file); 684 __putname(file); 685 return err; 686 } 687 688 static int hostfs_symlink(struct mnt_idmap *idmap, struct inode *ino, 689 struct dentry *dentry, const char *to) 690 { 691 char *file; 692 int err; 693 694 if ((file = dentry_name(dentry)) == NULL) 695 return -ENOMEM; 696 err = make_symlink(file, to); 697 __putname(file); 698 return err; 699 } 700 701 static int hostfs_mkdir(struct mnt_idmap *idmap, struct inode *ino, 702 struct dentry *dentry, umode_t mode) 703 { 704 char *file; 705 int err; 706 707 if ((file = dentry_name(dentry)) == NULL) 708 return -ENOMEM; 709 err = do_mkdir(file, mode); 710 __putname(file); 711 return err; 712 } 713 714 static int hostfs_rmdir(struct inode *ino, struct dentry *dentry) 715 { 716 char *file; 717 int err; 718 719 if ((file = dentry_name(dentry)) == NULL) 720 return -ENOMEM; 721 err = hostfs_do_rmdir(file); 722 __putname(file); 723 return err; 724 } 725 726 static int hostfs_mknod(struct mnt_idmap *idmap, struct inode *dir, 727 struct dentry *dentry, umode_t mode, dev_t dev) 728 { 729 struct inode *inode; 730 char *name; 731 int err; 732 733 name = dentry_name(dentry); 734 if (name == NULL) 735 return -ENOMEM; 736 737 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); 738 if (err) { 739 __putname(name); 740 return err; 741 } 742 743 inode = hostfs_iget(dir->i_sb, name); 744 __putname(name); 745 if (IS_ERR(inode)) 746 return PTR_ERR(inode); 747 748 d_instantiate(dentry, inode); 749 return 0; 750 } 751 752 static int hostfs_rename2(struct mnt_idmap *idmap, 753 struct inode *old_dir, struct dentry *old_dentry, 754 struct inode *new_dir, struct dentry *new_dentry, 755 unsigned int flags) 756 { 757 char *old_name, *new_name; 758 int err; 759 760 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) 761 return -EINVAL; 762 763 old_name = dentry_name(old_dentry); 764 if (old_name == NULL) 765 return -ENOMEM; 766 new_name = dentry_name(new_dentry); 767 if (new_name == NULL) { 768 __putname(old_name); 769 return -ENOMEM; 770 } 771 if (!flags) 772 err = rename_file(old_name, new_name); 773 else 774 err = rename2_file(old_name, new_name, flags); 775 776 __putname(old_name); 777 __putname(new_name); 778 return err; 779 } 780 781 static int hostfs_permission(struct mnt_idmap *idmap, 782 struct inode *ino, int desired) 783 { 784 char *name; 785 int r = 0, w = 0, x = 0, err; 786 787 if (desired & MAY_NOT_BLOCK) 788 return -ECHILD; 789 790 if (desired & MAY_READ) r = 1; 791 if (desired & MAY_WRITE) w = 1; 792 if (desired & MAY_EXEC) x = 1; 793 name = inode_name(ino); 794 if (name == NULL) 795 return -ENOMEM; 796 797 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || 798 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) 799 err = 0; 800 else 801 err = access_file(name, r, w, x); 802 __putname(name); 803 if (!err) 804 err = generic_permission(&nop_mnt_idmap, ino, desired); 805 return err; 806 } 807 808 static int hostfs_setattr(struct mnt_idmap *idmap, 809 struct dentry *dentry, struct iattr *attr) 810 { 811 struct inode *inode = d_inode(dentry); 812 struct hostfs_iattr attrs; 813 char *name; 814 int err; 815 816 int fd = HOSTFS_I(inode)->fd; 817 818 err = setattr_prepare(&nop_mnt_idmap, dentry, attr); 819 if (err) 820 return err; 821 822 if (append) 823 attr->ia_valid &= ~ATTR_SIZE; 824 825 attrs.ia_valid = 0; 826 if (attr->ia_valid & ATTR_MODE) { 827 attrs.ia_valid |= HOSTFS_ATTR_MODE; 828 attrs.ia_mode = attr->ia_mode; 829 } 830 if (attr->ia_valid & ATTR_UID) { 831 attrs.ia_valid |= HOSTFS_ATTR_UID; 832 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); 833 } 834 if (attr->ia_valid & ATTR_GID) { 835 attrs.ia_valid |= HOSTFS_ATTR_GID; 836 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); 837 } 838 if (attr->ia_valid & ATTR_SIZE) { 839 attrs.ia_valid |= HOSTFS_ATTR_SIZE; 840 attrs.ia_size = attr->ia_size; 841 } 842 if (attr->ia_valid & ATTR_ATIME) { 843 attrs.ia_valid |= HOSTFS_ATTR_ATIME; 844 attrs.ia_atime = (struct hostfs_timespec) 845 { attr->ia_atime.tv_sec, attr->ia_atime.tv_nsec }; 846 } 847 if (attr->ia_valid & ATTR_MTIME) { 848 attrs.ia_valid |= HOSTFS_ATTR_MTIME; 849 attrs.ia_mtime = (struct hostfs_timespec) 850 { attr->ia_mtime.tv_sec, attr->ia_mtime.tv_nsec }; 851 } 852 if (attr->ia_valid & ATTR_CTIME) { 853 attrs.ia_valid |= HOSTFS_ATTR_CTIME; 854 attrs.ia_ctime = (struct hostfs_timespec) 855 { attr->ia_ctime.tv_sec, attr->ia_ctime.tv_nsec }; 856 } 857 if (attr->ia_valid & ATTR_ATIME_SET) { 858 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; 859 } 860 if (attr->ia_valid & ATTR_MTIME_SET) { 861 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; 862 } 863 name = dentry_name(dentry); 864 if (name == NULL) 865 return -ENOMEM; 866 err = set_attr(name, &attrs, fd); 867 __putname(name); 868 if (err) 869 return err; 870 871 if ((attr->ia_valid & ATTR_SIZE) && 872 attr->ia_size != i_size_read(inode)) 873 truncate_setsize(inode, attr->ia_size); 874 875 setattr_copy(&nop_mnt_idmap, inode, attr); 876 mark_inode_dirty(inode); 877 return 0; 878 } 879 880 static const struct inode_operations hostfs_iops = { 881 .permission = hostfs_permission, 882 .setattr = hostfs_setattr, 883 }; 884 885 static const struct inode_operations hostfs_dir_iops = { 886 .create = hostfs_create, 887 .lookup = hostfs_lookup, 888 .link = hostfs_link, 889 .unlink = hostfs_unlink, 890 .symlink = hostfs_symlink, 891 .mkdir = hostfs_mkdir, 892 .rmdir = hostfs_rmdir, 893 .mknod = hostfs_mknod, 894 .rename = hostfs_rename2, 895 .permission = hostfs_permission, 896 .setattr = hostfs_setattr, 897 }; 898 899 static const char *hostfs_get_link(struct dentry *dentry, 900 struct inode *inode, 901 struct delayed_call *done) 902 { 903 char *link; 904 if (!dentry) 905 return ERR_PTR(-ECHILD); 906 link = kmalloc(PATH_MAX, GFP_KERNEL); 907 if (link) { 908 char *path = dentry_name(dentry); 909 int err = -ENOMEM; 910 if (path) { 911 err = hostfs_do_readlink(path, link, PATH_MAX); 912 if (err == PATH_MAX) 913 err = -E2BIG; 914 __putname(path); 915 } 916 if (err < 0) { 917 kfree(link); 918 return ERR_PTR(err); 919 } 920 } else { 921 return ERR_PTR(-ENOMEM); 922 } 923 924 set_delayed_call(done, kfree_link, link); 925 return link; 926 } 927 928 static const struct inode_operations hostfs_link_iops = { 929 .get_link = hostfs_get_link, 930 }; 931 932 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) 933 { 934 struct inode *root_inode; 935 char *host_root_path, *req_root = d; 936 int err; 937 938 sb->s_blocksize = 1024; 939 sb->s_blocksize_bits = 10; 940 sb->s_magic = HOSTFS_SUPER_MAGIC; 941 sb->s_op = &hostfs_sbops; 942 sb->s_d_op = &simple_dentry_operations; 943 sb->s_maxbytes = MAX_LFS_FILESIZE; 944 err = super_setup_bdi(sb); 945 if (err) 946 return err; 947 948 /* NULL is printed as '(null)' by printf(): avoid that. */ 949 if (req_root == NULL) 950 req_root = ""; 951 952 sb->s_fs_info = host_root_path = 953 kasprintf(GFP_KERNEL, "%s/%s", root_ino, req_root); 954 if (host_root_path == NULL) 955 return -ENOMEM; 956 957 root_inode = hostfs_iget(sb, host_root_path); 958 if (IS_ERR(root_inode)) 959 return PTR_ERR(root_inode); 960 961 if (S_ISLNK(root_inode->i_mode)) { 962 char *name; 963 964 iput(root_inode); 965 name = follow_link(host_root_path); 966 if (IS_ERR(name)) 967 return PTR_ERR(name); 968 969 root_inode = hostfs_iget(sb, name); 970 kfree(name); 971 if (IS_ERR(root_inode)) 972 return PTR_ERR(root_inode); 973 } 974 975 sb->s_root = d_make_root(root_inode); 976 if (sb->s_root == NULL) 977 return -ENOMEM; 978 979 return 0; 980 } 981 982 static struct dentry *hostfs_read_sb(struct file_system_type *type, 983 int flags, const char *dev_name, 984 void *data) 985 { 986 return mount_nodev(type, flags, data, hostfs_fill_sb_common); 987 } 988 989 static void hostfs_kill_sb(struct super_block *s) 990 { 991 kill_anon_super(s); 992 kfree(s->s_fs_info); 993 } 994 995 static struct file_system_type hostfs_type = { 996 .owner = THIS_MODULE, 997 .name = "hostfs", 998 .mount = hostfs_read_sb, 999 .kill_sb = hostfs_kill_sb, 1000 .fs_flags = 0, 1001 }; 1002 MODULE_ALIAS_FS("hostfs"); 1003 1004 static int __init init_hostfs(void) 1005 { 1006 hostfs_inode_cache = KMEM_CACHE(hostfs_inode_info, 0); 1007 if (!hostfs_inode_cache) 1008 return -ENOMEM; 1009 return register_filesystem(&hostfs_type); 1010 } 1011 1012 static void __exit exit_hostfs(void) 1013 { 1014 unregister_filesystem(&hostfs_type); 1015 kmem_cache_destroy(hostfs_inode_cache); 1016 } 1017 1018 module_init(init_hostfs) 1019 module_exit(exit_hostfs) 1020 MODULE_LICENSE("GPL"); 1021