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