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/mount.h> 18 #include <linux/namei.h> 19 #include "hostfs.h" 20 #include <init.h> 21 #include <kern.h> 22 23 struct hostfs_inode_info { 24 int fd; 25 fmode_t mode; 26 struct inode vfs_inode; 27 struct mutex open_mutex; 28 }; 29 30 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode) 31 { 32 return list_entry(inode, struct hostfs_inode_info, vfs_inode); 33 } 34 35 #define FILE_HOSTFS_I(file) HOSTFS_I(file_inode(file)) 36 37 /* Changed in hostfs_args before the kernel starts running */ 38 static char *root_ino = ""; 39 static int append = 0; 40 41 static const struct inode_operations hostfs_iops; 42 static const struct inode_operations hostfs_dir_iops; 43 static const struct inode_operations hostfs_link_iops; 44 45 #ifndef MODULE 46 static int __init hostfs_args(char *options, int *add) 47 { 48 char *ptr; 49 50 ptr = strchr(options, ','); 51 if (ptr != NULL) 52 *ptr++ = '\0'; 53 if (*options != '\0') 54 root_ino = options; 55 56 options = ptr; 57 while (options) { 58 ptr = strchr(options, ','); 59 if (ptr != NULL) 60 *ptr++ = '\0'; 61 if (*options != '\0') { 62 if (!strcmp(options, "append")) 63 append = 1; 64 else printf("hostfs_args - unsupported option - %s\n", 65 options); 66 } 67 options = ptr; 68 } 69 return 0; 70 } 71 72 __uml_setup("hostfs=", hostfs_args, 73 "hostfs=<root dir>,<flags>,...\n" 74 " This is used to set hostfs parameters. The root directory argument\n" 75 " is used to confine all hostfs mounts to within the specified directory\n" 76 " tree on the host. If this isn't specified, then a user inside UML can\n" 77 " mount anything on the host that's accessible to the user that's running\n" 78 " it.\n" 79 " The only flag currently supported is 'append', which specifies that all\n" 80 " files opened by hostfs will be opened in append mode.\n\n" 81 ); 82 #endif 83 84 static char *__dentry_name(struct dentry *dentry, char *name) 85 { 86 char *p = dentry_path_raw(dentry, name, PATH_MAX); 87 char *root; 88 size_t len; 89 90 root = dentry->d_sb->s_fs_info; 91 len = strlen(root); 92 if (IS_ERR(p)) { 93 __putname(name); 94 return NULL; 95 } 96 97 /* 98 * This function relies on the fact that dentry_path_raw() will place 99 * the path name at the end of the provided buffer. 100 */ 101 BUG_ON(p + strlen(p) + 1 != name + PATH_MAX); 102 103 strlcpy(name, root, PATH_MAX); 104 if (len > p - name) { 105 __putname(name); 106 return NULL; 107 } 108 109 if (p > name + len) 110 strcpy(name + len, p); 111 112 return name; 113 } 114 115 static char *dentry_name(struct dentry *dentry) 116 { 117 char *name = __getname(); 118 if (!name) 119 return NULL; 120 121 return __dentry_name(dentry, name); 122 } 123 124 static char *inode_name(struct inode *ino) 125 { 126 struct dentry *dentry; 127 char *name; 128 129 dentry = d_find_alias(ino); 130 if (!dentry) 131 return NULL; 132 133 name = dentry_name(dentry); 134 135 dput(dentry); 136 137 return name; 138 } 139 140 static char *follow_link(char *link) 141 { 142 int len, n; 143 char *name, *resolved, *end; 144 145 name = __getname(); 146 if (!name) { 147 n = -ENOMEM; 148 goto out_free; 149 } 150 151 n = hostfs_do_readlink(link, name, PATH_MAX); 152 if (n < 0) 153 goto out_free; 154 else if (n == PATH_MAX) { 155 n = -E2BIG; 156 goto out_free; 157 } 158 159 if (*name == '/') 160 return name; 161 162 end = strrchr(link, '/'); 163 if (end == NULL) 164 return name; 165 166 *(end + 1) = '\0'; 167 len = strlen(link) + strlen(name) + 1; 168 169 resolved = kmalloc(len, GFP_KERNEL); 170 if (resolved == NULL) { 171 n = -ENOMEM; 172 goto out_free; 173 } 174 175 sprintf(resolved, "%s%s", link, name); 176 __putname(name); 177 kfree(link); 178 return resolved; 179 180 out_free: 181 __putname(name); 182 return ERR_PTR(n); 183 } 184 185 static struct inode *hostfs_iget(struct super_block *sb) 186 { 187 struct inode *inode = new_inode(sb); 188 if (!inode) 189 return ERR_PTR(-ENOMEM); 190 return inode; 191 } 192 193 static int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf) 194 { 195 /* 196 * do_statfs uses struct statfs64 internally, but the linux kernel 197 * struct statfs still has 32-bit versions for most of these fields, 198 * so we convert them here 199 */ 200 int err; 201 long long f_blocks; 202 long long f_bfree; 203 long long f_bavail; 204 long long f_files; 205 long long f_ffree; 206 207 err = do_statfs(dentry->d_sb->s_fs_info, 208 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files, 209 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid), 210 &sf->f_namelen); 211 if (err) 212 return err; 213 sf->f_blocks = f_blocks; 214 sf->f_bfree = f_bfree; 215 sf->f_bavail = f_bavail; 216 sf->f_files = f_files; 217 sf->f_ffree = f_ffree; 218 sf->f_type = HOSTFS_SUPER_MAGIC; 219 return 0; 220 } 221 222 static struct inode *hostfs_alloc_inode(struct super_block *sb) 223 { 224 struct hostfs_inode_info *hi; 225 226 hi = kmalloc(sizeof(*hi), GFP_KERNEL_ACCOUNT); 227 if (hi == NULL) 228 return NULL; 229 hi->fd = -1; 230 hi->mode = 0; 231 inode_init_once(&hi->vfs_inode); 232 mutex_init(&hi->open_mutex); 233 return &hi->vfs_inode; 234 } 235 236 static void hostfs_evict_inode(struct inode *inode) 237 { 238 truncate_inode_pages_final(&inode->i_data); 239 clear_inode(inode); 240 if (HOSTFS_I(inode)->fd != -1) { 241 close_file(&HOSTFS_I(inode)->fd); 242 HOSTFS_I(inode)->fd = -1; 243 } 244 } 245 246 static void hostfs_i_callback(struct rcu_head *head) 247 { 248 struct inode *inode = container_of(head, struct inode, i_rcu); 249 kfree(HOSTFS_I(inode)); 250 } 251 252 static void hostfs_destroy_inode(struct inode *inode) 253 { 254 call_rcu(&inode->i_rcu, hostfs_i_callback); 255 } 256 257 static int hostfs_show_options(struct seq_file *seq, struct dentry *root) 258 { 259 const char *root_path = root->d_sb->s_fs_info; 260 size_t offset = strlen(root_ino) + 1; 261 262 if (strlen(root_path) > offset) 263 seq_show_option(seq, root_path + offset, NULL); 264 265 if (append) 266 seq_puts(seq, ",append"); 267 268 return 0; 269 } 270 271 static const struct super_operations hostfs_sbops = { 272 .alloc_inode = hostfs_alloc_inode, 273 .destroy_inode = hostfs_destroy_inode, 274 .evict_inode = hostfs_evict_inode, 275 .statfs = hostfs_statfs, 276 .show_options = hostfs_show_options, 277 }; 278 279 static int hostfs_readdir(struct file *file, struct dir_context *ctx) 280 { 281 void *dir; 282 char *name; 283 unsigned long long next, ino; 284 int error, len; 285 unsigned int type; 286 287 name = dentry_name(file->f_path.dentry); 288 if (name == NULL) 289 return -ENOMEM; 290 dir = open_dir(name, &error); 291 __putname(name); 292 if (dir == NULL) 293 return -error; 294 next = ctx->pos; 295 seek_dir(dir, next); 296 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) { 297 if (!dir_emit(ctx, name, len, ino, type)) 298 break; 299 ctx->pos = next; 300 } 301 close_dir(dir); 302 return 0; 303 } 304 305 static int hostfs_open(struct inode *ino, struct file *file) 306 { 307 char *name; 308 fmode_t mode; 309 int err; 310 int r, w, fd; 311 312 mode = file->f_mode & (FMODE_READ | FMODE_WRITE); 313 if ((mode & HOSTFS_I(ino)->mode) == mode) 314 return 0; 315 316 mode |= HOSTFS_I(ino)->mode; 317 318 retry: 319 r = w = 0; 320 321 if (mode & FMODE_READ) 322 r = 1; 323 if (mode & FMODE_WRITE) 324 r = w = 1; 325 326 name = dentry_name(file->f_path.dentry); 327 if (name == NULL) 328 return -ENOMEM; 329 330 fd = open_file(name, r, w, append); 331 __putname(name); 332 if (fd < 0) 333 return fd; 334 335 mutex_lock(&HOSTFS_I(ino)->open_mutex); 336 /* somebody else had handled it first? */ 337 if ((mode & HOSTFS_I(ino)->mode) == mode) { 338 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 339 close_file(&fd); 340 return 0; 341 } 342 if ((mode | HOSTFS_I(ino)->mode) != mode) { 343 mode |= HOSTFS_I(ino)->mode; 344 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 345 close_file(&fd); 346 goto retry; 347 } 348 if (HOSTFS_I(ino)->fd == -1) { 349 HOSTFS_I(ino)->fd = fd; 350 } else { 351 err = replace_file(fd, HOSTFS_I(ino)->fd); 352 close_file(&fd); 353 if (err < 0) { 354 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 355 return err; 356 } 357 } 358 HOSTFS_I(ino)->mode = mode; 359 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 360 361 return 0; 362 } 363 364 static int hostfs_file_release(struct inode *inode, struct file *file) 365 { 366 filemap_write_and_wait(inode->i_mapping); 367 368 return 0; 369 } 370 371 static int hostfs_fsync(struct file *file, loff_t start, loff_t end, 372 int datasync) 373 { 374 struct inode *inode = file->f_mapping->host; 375 int ret; 376 377 ret = file_write_and_wait_range(file, start, end); 378 if (ret) 379 return ret; 380 381 inode_lock(inode); 382 ret = fsync_file(HOSTFS_I(inode)->fd, datasync); 383 inode_unlock(inode); 384 385 return ret; 386 } 387 388 static const struct file_operations hostfs_file_fops = { 389 .llseek = generic_file_llseek, 390 .splice_read = generic_file_splice_read, 391 .read_iter = generic_file_read_iter, 392 .write_iter = generic_file_write_iter, 393 .mmap = generic_file_mmap, 394 .open = hostfs_open, 395 .release = hostfs_file_release, 396 .fsync = hostfs_fsync, 397 }; 398 399 static const struct file_operations hostfs_dir_fops = { 400 .llseek = generic_file_llseek, 401 .iterate_shared = hostfs_readdir, 402 .read = generic_read_dir, 403 .open = hostfs_open, 404 .fsync = hostfs_fsync, 405 }; 406 407 static int hostfs_writepage(struct page *page, struct writeback_control *wbc) 408 { 409 struct address_space *mapping = page->mapping; 410 struct inode *inode = mapping->host; 411 char *buffer; 412 loff_t base = page_offset(page); 413 int count = PAGE_SIZE; 414 int end_index = inode->i_size >> PAGE_SHIFT; 415 int err; 416 417 if (page->index >= end_index) 418 count = inode->i_size & (PAGE_SIZE-1); 419 420 buffer = kmap(page); 421 422 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count); 423 if (err != count) { 424 ClearPageUptodate(page); 425 goto out; 426 } 427 428 if (base > inode->i_size) 429 inode->i_size = base; 430 431 if (PageError(page)) 432 ClearPageError(page); 433 err = 0; 434 435 out: 436 kunmap(page); 437 438 unlock_page(page); 439 return err; 440 } 441 442 static int hostfs_readpage(struct file *file, struct page *page) 443 { 444 char *buffer; 445 loff_t start = page_offset(page); 446 int bytes_read, ret = 0; 447 448 buffer = kmap(page); 449 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, 450 PAGE_SIZE); 451 if (bytes_read < 0) { 452 ClearPageUptodate(page); 453 SetPageError(page); 454 ret = bytes_read; 455 goto out; 456 } 457 458 memset(buffer + bytes_read, 0, PAGE_SIZE - bytes_read); 459 460 ClearPageError(page); 461 SetPageUptodate(page); 462 463 out: 464 flush_dcache_page(page); 465 kunmap(page); 466 unlock_page(page); 467 return ret; 468 } 469 470 static int hostfs_write_begin(struct file *file, struct address_space *mapping, 471 loff_t pos, unsigned len, unsigned flags, 472 struct page **pagep, void **fsdata) 473 { 474 pgoff_t index = pos >> PAGE_SHIFT; 475 476 *pagep = grab_cache_page_write_begin(mapping, index, flags); 477 if (!*pagep) 478 return -ENOMEM; 479 return 0; 480 } 481 482 static int hostfs_write_end(struct file *file, struct address_space *mapping, 483 loff_t pos, unsigned len, unsigned copied, 484 struct page *page, void *fsdata) 485 { 486 struct inode *inode = mapping->host; 487 void *buffer; 488 unsigned from = pos & (PAGE_SIZE - 1); 489 int err; 490 491 buffer = kmap(page); 492 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); 493 kunmap(page); 494 495 if (!PageUptodate(page) && err == PAGE_SIZE) 496 SetPageUptodate(page); 497 498 /* 499 * If err > 0, write_file has added err to pos, so we are comparing 500 * i_size against the last byte written. 501 */ 502 if (err > 0 && (pos > inode->i_size)) 503 inode->i_size = pos; 504 unlock_page(page); 505 put_page(page); 506 507 return err; 508 } 509 510 static const struct address_space_operations hostfs_aops = { 511 .writepage = hostfs_writepage, 512 .readpage = hostfs_readpage, 513 .set_page_dirty = __set_page_dirty_nobuffers, 514 .write_begin = hostfs_write_begin, 515 .write_end = hostfs_write_end, 516 }; 517 518 static int read_name(struct inode *ino, char *name) 519 { 520 dev_t rdev; 521 struct hostfs_stat st; 522 int err = stat_file(name, &st, -1); 523 if (err) 524 return err; 525 526 /* Reencode maj and min with the kernel encoding.*/ 527 rdev = MKDEV(st.maj, st.min); 528 529 switch (st.mode & S_IFMT) { 530 case S_IFLNK: 531 ino->i_op = &hostfs_link_iops; 532 break; 533 case S_IFDIR: 534 ino->i_op = &hostfs_dir_iops; 535 ino->i_fop = &hostfs_dir_fops; 536 break; 537 case S_IFCHR: 538 case S_IFBLK: 539 case S_IFIFO: 540 case S_IFSOCK: 541 init_special_inode(ino, st.mode & S_IFMT, rdev); 542 ino->i_op = &hostfs_iops; 543 break; 544 case S_IFREG: 545 ino->i_op = &hostfs_iops; 546 ino->i_fop = &hostfs_file_fops; 547 ino->i_mapping->a_ops = &hostfs_aops; 548 break; 549 default: 550 return -EIO; 551 } 552 553 ino->i_ino = st.ino; 554 ino->i_mode = st.mode; 555 set_nlink(ino, st.nlink); 556 i_uid_write(ino, st.uid); 557 i_gid_write(ino, st.gid); 558 ino->i_atime = timespec_to_timespec64(st.atime); 559 ino->i_mtime = timespec_to_timespec64(st.mtime); 560 ino->i_ctime = timespec_to_timespec64(st.ctime); 561 ino->i_size = st.size; 562 ino->i_blocks = st.blocks; 563 return 0; 564 } 565 566 static int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 567 bool excl) 568 { 569 struct inode *inode; 570 char *name; 571 int error, fd; 572 573 inode = hostfs_iget(dir->i_sb); 574 if (IS_ERR(inode)) { 575 error = PTR_ERR(inode); 576 goto out; 577 } 578 579 error = -ENOMEM; 580 name = dentry_name(dentry); 581 if (name == NULL) 582 goto out_put; 583 584 fd = file_create(name, mode & 0777); 585 if (fd < 0) 586 error = fd; 587 else 588 error = read_name(inode, name); 589 590 __putname(name); 591 if (error) 592 goto out_put; 593 594 HOSTFS_I(inode)->fd = fd; 595 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; 596 d_instantiate(dentry, inode); 597 return 0; 598 599 out_put: 600 iput(inode); 601 out: 602 return error; 603 } 604 605 static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, 606 unsigned int flags) 607 { 608 struct inode *inode; 609 char *name; 610 int err; 611 612 inode = hostfs_iget(ino->i_sb); 613 if (IS_ERR(inode)) 614 goto out; 615 616 err = -ENOMEM; 617 name = dentry_name(dentry); 618 if (name) { 619 err = read_name(inode, name); 620 __putname(name); 621 } 622 if (err) { 623 iput(inode); 624 inode = (err == -ENOENT) ? NULL : ERR_PTR(err); 625 } 626 out: 627 return d_splice_alias(inode, dentry); 628 } 629 630 static int hostfs_link(struct dentry *to, struct inode *ino, 631 struct dentry *from) 632 { 633 char *from_name, *to_name; 634 int err; 635 636 if ((from_name = dentry_name(from)) == NULL) 637 return -ENOMEM; 638 to_name = dentry_name(to); 639 if (to_name == NULL) { 640 __putname(from_name); 641 return -ENOMEM; 642 } 643 err = link_file(to_name, from_name); 644 __putname(from_name); 645 __putname(to_name); 646 return err; 647 } 648 649 static int hostfs_unlink(struct inode *ino, struct dentry *dentry) 650 { 651 char *file; 652 int err; 653 654 if (append) 655 return -EPERM; 656 657 if ((file = dentry_name(dentry)) == NULL) 658 return -ENOMEM; 659 660 err = unlink_file(file); 661 __putname(file); 662 return err; 663 } 664 665 static int hostfs_symlink(struct inode *ino, struct dentry *dentry, 666 const char *to) 667 { 668 char *file; 669 int err; 670 671 if ((file = dentry_name(dentry)) == NULL) 672 return -ENOMEM; 673 err = make_symlink(file, to); 674 __putname(file); 675 return err; 676 } 677 678 static int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode) 679 { 680 char *file; 681 int err; 682 683 if ((file = dentry_name(dentry)) == NULL) 684 return -ENOMEM; 685 err = do_mkdir(file, mode); 686 __putname(file); 687 return err; 688 } 689 690 static int hostfs_rmdir(struct inode *ino, struct dentry *dentry) 691 { 692 char *file; 693 int err; 694 695 if ((file = dentry_name(dentry)) == NULL) 696 return -ENOMEM; 697 err = hostfs_do_rmdir(file); 698 __putname(file); 699 return err; 700 } 701 702 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 703 { 704 struct inode *inode; 705 char *name; 706 int err; 707 708 inode = hostfs_iget(dir->i_sb); 709 if (IS_ERR(inode)) { 710 err = PTR_ERR(inode); 711 goto out; 712 } 713 714 err = -ENOMEM; 715 name = dentry_name(dentry); 716 if (name == NULL) 717 goto out_put; 718 719 init_special_inode(inode, mode, dev); 720 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); 721 if (err) 722 goto out_free; 723 724 err = read_name(inode, name); 725 __putname(name); 726 if (err) 727 goto out_put; 728 729 d_instantiate(dentry, inode); 730 return 0; 731 732 out_free: 733 __putname(name); 734 out_put: 735 iput(inode); 736 out: 737 return err; 738 } 739 740 static int hostfs_rename2(struct inode *old_dir, struct dentry *old_dentry, 741 struct inode *new_dir, struct dentry *new_dentry, 742 unsigned int flags) 743 { 744 char *old_name, *new_name; 745 int err; 746 747 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) 748 return -EINVAL; 749 750 old_name = dentry_name(old_dentry); 751 if (old_name == NULL) 752 return -ENOMEM; 753 new_name = dentry_name(new_dentry); 754 if (new_name == NULL) { 755 __putname(old_name); 756 return -ENOMEM; 757 } 758 if (!flags) 759 err = rename_file(old_name, new_name); 760 else 761 err = rename2_file(old_name, new_name, flags); 762 763 __putname(old_name); 764 __putname(new_name); 765 return err; 766 } 767 768 static int hostfs_permission(struct inode *ino, int desired) 769 { 770 char *name; 771 int r = 0, w = 0, x = 0, err; 772 773 if (desired & MAY_NOT_BLOCK) 774 return -ECHILD; 775 776 if (desired & MAY_READ) r = 1; 777 if (desired & MAY_WRITE) w = 1; 778 if (desired & MAY_EXEC) x = 1; 779 name = inode_name(ino); 780 if (name == NULL) 781 return -ENOMEM; 782 783 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || 784 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) 785 err = 0; 786 else 787 err = access_file(name, r, w, x); 788 __putname(name); 789 if (!err) 790 err = generic_permission(ino, desired); 791 return err; 792 } 793 794 static int hostfs_setattr(struct dentry *dentry, struct iattr *attr) 795 { 796 struct inode *inode = d_inode(dentry); 797 struct hostfs_iattr attrs; 798 char *name; 799 int err; 800 801 int fd = HOSTFS_I(inode)->fd; 802 803 err = setattr_prepare(dentry, attr); 804 if (err) 805 return err; 806 807 if (append) 808 attr->ia_valid &= ~ATTR_SIZE; 809 810 attrs.ia_valid = 0; 811 if (attr->ia_valid & ATTR_MODE) { 812 attrs.ia_valid |= HOSTFS_ATTR_MODE; 813 attrs.ia_mode = attr->ia_mode; 814 } 815 if (attr->ia_valid & ATTR_UID) { 816 attrs.ia_valid |= HOSTFS_ATTR_UID; 817 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); 818 } 819 if (attr->ia_valid & ATTR_GID) { 820 attrs.ia_valid |= HOSTFS_ATTR_GID; 821 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); 822 } 823 if (attr->ia_valid & ATTR_SIZE) { 824 attrs.ia_valid |= HOSTFS_ATTR_SIZE; 825 attrs.ia_size = attr->ia_size; 826 } 827 if (attr->ia_valid & ATTR_ATIME) { 828 attrs.ia_valid |= HOSTFS_ATTR_ATIME; 829 attrs.ia_atime = timespec64_to_timespec(attr->ia_atime); 830 } 831 if (attr->ia_valid & ATTR_MTIME) { 832 attrs.ia_valid |= HOSTFS_ATTR_MTIME; 833 attrs.ia_mtime = timespec64_to_timespec(attr->ia_mtime); 834 } 835 if (attr->ia_valid & ATTR_CTIME) { 836 attrs.ia_valid |= HOSTFS_ATTR_CTIME; 837 attrs.ia_ctime = timespec64_to_timespec(attr->ia_ctime); 838 } 839 if (attr->ia_valid & ATTR_ATIME_SET) { 840 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; 841 } 842 if (attr->ia_valid & ATTR_MTIME_SET) { 843 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; 844 } 845 name = dentry_name(dentry); 846 if (name == NULL) 847 return -ENOMEM; 848 err = set_attr(name, &attrs, fd); 849 __putname(name); 850 if (err) 851 return err; 852 853 if ((attr->ia_valid & ATTR_SIZE) && 854 attr->ia_size != i_size_read(inode)) 855 truncate_setsize(inode, attr->ia_size); 856 857 setattr_copy(inode, attr); 858 mark_inode_dirty(inode); 859 return 0; 860 } 861 862 static const struct inode_operations hostfs_iops = { 863 .permission = hostfs_permission, 864 .setattr = hostfs_setattr, 865 }; 866 867 static const struct inode_operations hostfs_dir_iops = { 868 .create = hostfs_create, 869 .lookup = hostfs_lookup, 870 .link = hostfs_link, 871 .unlink = hostfs_unlink, 872 .symlink = hostfs_symlink, 873 .mkdir = hostfs_mkdir, 874 .rmdir = hostfs_rmdir, 875 .mknod = hostfs_mknod, 876 .rename = hostfs_rename2, 877 .permission = hostfs_permission, 878 .setattr = hostfs_setattr, 879 }; 880 881 static const char *hostfs_get_link(struct dentry *dentry, 882 struct inode *inode, 883 struct delayed_call *done) 884 { 885 char *link; 886 if (!dentry) 887 return ERR_PTR(-ECHILD); 888 link = kmalloc(PATH_MAX, GFP_KERNEL); 889 if (link) { 890 char *path = dentry_name(dentry); 891 int err = -ENOMEM; 892 if (path) { 893 err = hostfs_do_readlink(path, link, PATH_MAX); 894 if (err == PATH_MAX) 895 err = -E2BIG; 896 __putname(path); 897 } 898 if (err < 0) { 899 kfree(link); 900 return ERR_PTR(err); 901 } 902 } else { 903 return ERR_PTR(-ENOMEM); 904 } 905 906 set_delayed_call(done, kfree_link, link); 907 return link; 908 } 909 910 static const struct inode_operations hostfs_link_iops = { 911 .get_link = hostfs_get_link, 912 }; 913 914 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) 915 { 916 struct inode *root_inode; 917 char *host_root_path, *req_root = d; 918 int err; 919 920 sb->s_blocksize = 1024; 921 sb->s_blocksize_bits = 10; 922 sb->s_magic = HOSTFS_SUPER_MAGIC; 923 sb->s_op = &hostfs_sbops; 924 sb->s_d_op = &simple_dentry_operations; 925 sb->s_maxbytes = MAX_LFS_FILESIZE; 926 927 /* NULL is printed as <NULL> by sprintf: avoid that. */ 928 if (req_root == NULL) 929 req_root = ""; 930 931 err = -ENOMEM; 932 sb->s_fs_info = host_root_path = 933 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL); 934 if (host_root_path == NULL) 935 goto out; 936 937 sprintf(host_root_path, "%s/%s", root_ino, req_root); 938 939 root_inode = new_inode(sb); 940 if (!root_inode) 941 goto out; 942 943 err = read_name(root_inode, host_root_path); 944 if (err) 945 goto out_put; 946 947 if (S_ISLNK(root_inode->i_mode)) { 948 char *name = follow_link(host_root_path); 949 if (IS_ERR(name)) { 950 err = PTR_ERR(name); 951 goto out_put; 952 } 953 err = read_name(root_inode, name); 954 kfree(name); 955 if (err) 956 goto out_put; 957 } 958 959 err = -ENOMEM; 960 sb->s_root = d_make_root(root_inode); 961 if (sb->s_root == NULL) 962 goto out; 963 964 return 0; 965 966 out_put: 967 iput(root_inode); 968 out: 969 return err; 970 } 971 972 static struct dentry *hostfs_read_sb(struct file_system_type *type, 973 int flags, const char *dev_name, 974 void *data) 975 { 976 return mount_nodev(type, flags, data, hostfs_fill_sb_common); 977 } 978 979 static void hostfs_kill_sb(struct super_block *s) 980 { 981 kill_anon_super(s); 982 kfree(s->s_fs_info); 983 } 984 985 static struct file_system_type hostfs_type = { 986 .owner = THIS_MODULE, 987 .name = "hostfs", 988 .mount = hostfs_read_sb, 989 .kill_sb = hostfs_kill_sb, 990 .fs_flags = 0, 991 }; 992 MODULE_ALIAS_FS("hostfs"); 993 994 static int __init init_hostfs(void) 995 { 996 return register_filesystem(&hostfs_type); 997 } 998 999 static void __exit exit_hostfs(void) 1000 { 1001 unregister_filesystem(&hostfs_type); 1002 } 1003 1004 module_init(init_hostfs) 1005 module_exit(exit_hostfs) 1006 MODULE_LICENSE("GPL"); 1007