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