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_readpage(struct file *file, struct page *page) 438 { 439 char *buffer; 440 loff_t start = page_offset(page); 441 int bytes_read, ret = 0; 442 443 buffer = kmap(page); 444 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, 445 PAGE_SIZE); 446 if (bytes_read < 0) { 447 ClearPageUptodate(page); 448 SetPageError(page); 449 ret = bytes_read; 450 goto out; 451 } 452 453 memset(buffer + bytes_read, 0, PAGE_SIZE - bytes_read); 454 455 ClearPageError(page); 456 SetPageUptodate(page); 457 458 out: 459 flush_dcache_page(page); 460 kunmap(page); 461 unlock_page(page); 462 return ret; 463 } 464 465 static int hostfs_write_begin(struct file *file, struct address_space *mapping, 466 loff_t pos, unsigned len, unsigned flags, 467 struct page **pagep, void **fsdata) 468 { 469 pgoff_t index = pos >> PAGE_SHIFT; 470 471 *pagep = grab_cache_page_write_begin(mapping, index, flags); 472 if (!*pagep) 473 return -ENOMEM; 474 return 0; 475 } 476 477 static int hostfs_write_end(struct file *file, struct address_space *mapping, 478 loff_t pos, unsigned len, unsigned copied, 479 struct page *page, void *fsdata) 480 { 481 struct inode *inode = mapping->host; 482 void *buffer; 483 unsigned from = pos & (PAGE_SIZE - 1); 484 int err; 485 486 buffer = kmap(page); 487 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); 488 kunmap(page); 489 490 if (!PageUptodate(page) && err == PAGE_SIZE) 491 SetPageUptodate(page); 492 493 /* 494 * If err > 0, write_file has added err to pos, so we are comparing 495 * i_size against the last byte written. 496 */ 497 if (err > 0 && (pos > inode->i_size)) 498 inode->i_size = pos; 499 unlock_page(page); 500 put_page(page); 501 502 return err; 503 } 504 505 static const struct address_space_operations hostfs_aops = { 506 .writepage = hostfs_writepage, 507 .readpage = hostfs_readpage, 508 .dirty_folio = filemap_dirty_folio, 509 .write_begin = hostfs_write_begin, 510 .write_end = hostfs_write_end, 511 }; 512 513 static int read_name(struct inode *ino, char *name) 514 { 515 dev_t rdev; 516 struct hostfs_stat st; 517 int err = stat_file(name, &st, -1); 518 if (err) 519 return err; 520 521 /* Reencode maj and min with the kernel encoding.*/ 522 rdev = MKDEV(st.maj, st.min); 523 524 switch (st.mode & S_IFMT) { 525 case S_IFLNK: 526 ino->i_op = &hostfs_link_iops; 527 break; 528 case S_IFDIR: 529 ino->i_op = &hostfs_dir_iops; 530 ino->i_fop = &hostfs_dir_fops; 531 break; 532 case S_IFCHR: 533 case S_IFBLK: 534 case S_IFIFO: 535 case S_IFSOCK: 536 init_special_inode(ino, st.mode & S_IFMT, rdev); 537 ino->i_op = &hostfs_iops; 538 break; 539 case S_IFREG: 540 ino->i_op = &hostfs_iops; 541 ino->i_fop = &hostfs_file_fops; 542 ino->i_mapping->a_ops = &hostfs_aops; 543 break; 544 default: 545 return -EIO; 546 } 547 548 ino->i_ino = st.ino; 549 ino->i_mode = st.mode; 550 set_nlink(ino, st.nlink); 551 i_uid_write(ino, st.uid); 552 i_gid_write(ino, st.gid); 553 ino->i_atime = (struct timespec64){ st.atime.tv_sec, st.atime.tv_nsec }; 554 ino->i_mtime = (struct timespec64){ st.mtime.tv_sec, st.mtime.tv_nsec }; 555 ino->i_ctime = (struct timespec64){ st.ctime.tv_sec, st.ctime.tv_nsec }; 556 ino->i_size = st.size; 557 ino->i_blocks = st.blocks; 558 return 0; 559 } 560 561 static int hostfs_create(struct user_namespace *mnt_userns, struct inode *dir, 562 struct dentry *dentry, umode_t mode, bool excl) 563 { 564 struct inode *inode; 565 char *name; 566 int error, fd; 567 568 inode = hostfs_iget(dir->i_sb); 569 if (IS_ERR(inode)) { 570 error = PTR_ERR(inode); 571 goto out; 572 } 573 574 error = -ENOMEM; 575 name = dentry_name(dentry); 576 if (name == NULL) 577 goto out_put; 578 579 fd = file_create(name, mode & 0777); 580 if (fd < 0) 581 error = fd; 582 else 583 error = read_name(inode, name); 584 585 __putname(name); 586 if (error) 587 goto out_put; 588 589 HOSTFS_I(inode)->fd = fd; 590 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; 591 d_instantiate(dentry, inode); 592 return 0; 593 594 out_put: 595 iput(inode); 596 out: 597 return error; 598 } 599 600 static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, 601 unsigned int flags) 602 { 603 struct inode *inode; 604 char *name; 605 int err; 606 607 inode = hostfs_iget(ino->i_sb); 608 if (IS_ERR(inode)) 609 goto out; 610 611 err = -ENOMEM; 612 name = dentry_name(dentry); 613 if (name) { 614 err = read_name(inode, name); 615 __putname(name); 616 } 617 if (err) { 618 iput(inode); 619 inode = (err == -ENOENT) ? NULL : ERR_PTR(err); 620 } 621 out: 622 return d_splice_alias(inode, dentry); 623 } 624 625 static int hostfs_link(struct dentry *to, struct inode *ino, 626 struct dentry *from) 627 { 628 char *from_name, *to_name; 629 int err; 630 631 if ((from_name = dentry_name(from)) == NULL) 632 return -ENOMEM; 633 to_name = dentry_name(to); 634 if (to_name == NULL) { 635 __putname(from_name); 636 return -ENOMEM; 637 } 638 err = link_file(to_name, from_name); 639 __putname(from_name); 640 __putname(to_name); 641 return err; 642 } 643 644 static int hostfs_unlink(struct inode *ino, struct dentry *dentry) 645 { 646 char *file; 647 int err; 648 649 if (append) 650 return -EPERM; 651 652 if ((file = dentry_name(dentry)) == NULL) 653 return -ENOMEM; 654 655 err = unlink_file(file); 656 __putname(file); 657 return err; 658 } 659 660 static int hostfs_symlink(struct user_namespace *mnt_userns, struct inode *ino, 661 struct dentry *dentry, const char *to) 662 { 663 char *file; 664 int err; 665 666 if ((file = dentry_name(dentry)) == NULL) 667 return -ENOMEM; 668 err = make_symlink(file, to); 669 __putname(file); 670 return err; 671 } 672 673 static int hostfs_mkdir(struct user_namespace *mnt_userns, struct inode *ino, 674 struct dentry *dentry, umode_t mode) 675 { 676 char *file; 677 int err; 678 679 if ((file = dentry_name(dentry)) == NULL) 680 return -ENOMEM; 681 err = do_mkdir(file, mode); 682 __putname(file); 683 return err; 684 } 685 686 static int hostfs_rmdir(struct inode *ino, struct dentry *dentry) 687 { 688 char *file; 689 int err; 690 691 if ((file = dentry_name(dentry)) == NULL) 692 return -ENOMEM; 693 err = hostfs_do_rmdir(file); 694 __putname(file); 695 return err; 696 } 697 698 static int hostfs_mknod(struct user_namespace *mnt_userns, struct inode *dir, 699 struct dentry *dentry, umode_t mode, dev_t dev) 700 { 701 struct inode *inode; 702 char *name; 703 int err; 704 705 inode = hostfs_iget(dir->i_sb); 706 if (IS_ERR(inode)) { 707 err = PTR_ERR(inode); 708 goto out; 709 } 710 711 err = -ENOMEM; 712 name = dentry_name(dentry); 713 if (name == NULL) 714 goto out_put; 715 716 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); 717 if (err) 718 goto out_free; 719 720 err = read_name(inode, name); 721 __putname(name); 722 if (err) 723 goto out_put; 724 725 d_instantiate(dentry, inode); 726 return 0; 727 728 out_free: 729 __putname(name); 730 out_put: 731 iput(inode); 732 out: 733 return err; 734 } 735 736 static int hostfs_rename2(struct user_namespace *mnt_userns, 737 struct inode *old_dir, struct dentry *old_dentry, 738 struct inode *new_dir, struct dentry *new_dentry, 739 unsigned int flags) 740 { 741 char *old_name, *new_name; 742 int err; 743 744 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) 745 return -EINVAL; 746 747 old_name = dentry_name(old_dentry); 748 if (old_name == NULL) 749 return -ENOMEM; 750 new_name = dentry_name(new_dentry); 751 if (new_name == NULL) { 752 __putname(old_name); 753 return -ENOMEM; 754 } 755 if (!flags) 756 err = rename_file(old_name, new_name); 757 else 758 err = rename2_file(old_name, new_name, flags); 759 760 __putname(old_name); 761 __putname(new_name); 762 return err; 763 } 764 765 static int hostfs_permission(struct user_namespace *mnt_userns, 766 struct inode *ino, int desired) 767 { 768 char *name; 769 int r = 0, w = 0, x = 0, err; 770 771 if (desired & MAY_NOT_BLOCK) 772 return -ECHILD; 773 774 if (desired & MAY_READ) r = 1; 775 if (desired & MAY_WRITE) w = 1; 776 if (desired & MAY_EXEC) x = 1; 777 name = inode_name(ino); 778 if (name == NULL) 779 return -ENOMEM; 780 781 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || 782 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) 783 err = 0; 784 else 785 err = access_file(name, r, w, x); 786 __putname(name); 787 if (!err) 788 err = generic_permission(&init_user_ns, ino, desired); 789 return err; 790 } 791 792 static int hostfs_setattr(struct user_namespace *mnt_userns, 793 struct dentry *dentry, struct iattr *attr) 794 { 795 struct inode *inode = d_inode(dentry); 796 struct hostfs_iattr attrs; 797 char *name; 798 int err; 799 800 int fd = HOSTFS_I(inode)->fd; 801 802 err = setattr_prepare(&init_user_ns, dentry, attr); 803 if (err) 804 return err; 805 806 if (append) 807 attr->ia_valid &= ~ATTR_SIZE; 808 809 attrs.ia_valid = 0; 810 if (attr->ia_valid & ATTR_MODE) { 811 attrs.ia_valid |= HOSTFS_ATTR_MODE; 812 attrs.ia_mode = attr->ia_mode; 813 } 814 if (attr->ia_valid & ATTR_UID) { 815 attrs.ia_valid |= HOSTFS_ATTR_UID; 816 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); 817 } 818 if (attr->ia_valid & ATTR_GID) { 819 attrs.ia_valid |= HOSTFS_ATTR_GID; 820 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); 821 } 822 if (attr->ia_valid & ATTR_SIZE) { 823 attrs.ia_valid |= HOSTFS_ATTR_SIZE; 824 attrs.ia_size = attr->ia_size; 825 } 826 if (attr->ia_valid & ATTR_ATIME) { 827 attrs.ia_valid |= HOSTFS_ATTR_ATIME; 828 attrs.ia_atime = (struct hostfs_timespec) 829 { attr->ia_atime.tv_sec, attr->ia_atime.tv_nsec }; 830 } 831 if (attr->ia_valid & ATTR_MTIME) { 832 attrs.ia_valid |= HOSTFS_ATTR_MTIME; 833 attrs.ia_mtime = (struct hostfs_timespec) 834 { attr->ia_mtime.tv_sec, attr->ia_mtime.tv_nsec }; 835 } 836 if (attr->ia_valid & ATTR_CTIME) { 837 attrs.ia_valid |= HOSTFS_ATTR_CTIME; 838 attrs.ia_ctime = (struct hostfs_timespec) 839 { attr->ia_ctime.tv_sec, attr->ia_ctime.tv_nsec }; 840 } 841 if (attr->ia_valid & ATTR_ATIME_SET) { 842 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; 843 } 844 if (attr->ia_valid & ATTR_MTIME_SET) { 845 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; 846 } 847 name = dentry_name(dentry); 848 if (name == NULL) 849 return -ENOMEM; 850 err = set_attr(name, &attrs, fd); 851 __putname(name); 852 if (err) 853 return err; 854 855 if ((attr->ia_valid & ATTR_SIZE) && 856 attr->ia_size != i_size_read(inode)) 857 truncate_setsize(inode, attr->ia_size); 858 859 setattr_copy(&init_user_ns, inode, attr); 860 mark_inode_dirty(inode); 861 return 0; 862 } 863 864 static const struct inode_operations hostfs_iops = { 865 .permission = hostfs_permission, 866 .setattr = hostfs_setattr, 867 }; 868 869 static const struct inode_operations hostfs_dir_iops = { 870 .create = hostfs_create, 871 .lookup = hostfs_lookup, 872 .link = hostfs_link, 873 .unlink = hostfs_unlink, 874 .symlink = hostfs_symlink, 875 .mkdir = hostfs_mkdir, 876 .rmdir = hostfs_rmdir, 877 .mknod = hostfs_mknod, 878 .rename = hostfs_rename2, 879 .permission = hostfs_permission, 880 .setattr = hostfs_setattr, 881 }; 882 883 static const char *hostfs_get_link(struct dentry *dentry, 884 struct inode *inode, 885 struct delayed_call *done) 886 { 887 char *link; 888 if (!dentry) 889 return ERR_PTR(-ECHILD); 890 link = kmalloc(PATH_MAX, GFP_KERNEL); 891 if (link) { 892 char *path = dentry_name(dentry); 893 int err = -ENOMEM; 894 if (path) { 895 err = hostfs_do_readlink(path, link, PATH_MAX); 896 if (err == PATH_MAX) 897 err = -E2BIG; 898 __putname(path); 899 } 900 if (err < 0) { 901 kfree(link); 902 return ERR_PTR(err); 903 } 904 } else { 905 return ERR_PTR(-ENOMEM); 906 } 907 908 set_delayed_call(done, kfree_link, link); 909 return link; 910 } 911 912 static const struct inode_operations hostfs_link_iops = { 913 .get_link = hostfs_get_link, 914 }; 915 916 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) 917 { 918 struct inode *root_inode; 919 char *host_root_path, *req_root = d; 920 int err; 921 922 sb->s_blocksize = 1024; 923 sb->s_blocksize_bits = 10; 924 sb->s_magic = HOSTFS_SUPER_MAGIC; 925 sb->s_op = &hostfs_sbops; 926 sb->s_d_op = &simple_dentry_operations; 927 sb->s_maxbytes = MAX_LFS_FILESIZE; 928 err = super_setup_bdi(sb); 929 if (err) 930 goto out; 931 932 /* NULL is printed as '(null)' by printf(): avoid that. */ 933 if (req_root == NULL) 934 req_root = ""; 935 936 err = -ENOMEM; 937 sb->s_fs_info = host_root_path = 938 kasprintf(GFP_KERNEL, "%s/%s", root_ino, req_root); 939 if (host_root_path == NULL) 940 goto out; 941 942 root_inode = new_inode(sb); 943 if (!root_inode) 944 goto out; 945 946 err = read_name(root_inode, host_root_path); 947 if (err) 948 goto out_put; 949 950 if (S_ISLNK(root_inode->i_mode)) { 951 char *name = follow_link(host_root_path); 952 if (IS_ERR(name)) { 953 err = PTR_ERR(name); 954 goto out_put; 955 } 956 err = read_name(root_inode, name); 957 kfree(name); 958 if (err) 959 goto out_put; 960 } 961 962 err = -ENOMEM; 963 sb->s_root = d_make_root(root_inode); 964 if (sb->s_root == NULL) 965 goto out; 966 967 return 0; 968 969 out_put: 970 iput(root_inode); 971 out: 972 return err; 973 } 974 975 static struct dentry *hostfs_read_sb(struct file_system_type *type, 976 int flags, const char *dev_name, 977 void *data) 978 { 979 return mount_nodev(type, flags, data, hostfs_fill_sb_common); 980 } 981 982 static void hostfs_kill_sb(struct super_block *s) 983 { 984 kill_anon_super(s); 985 kfree(s->s_fs_info); 986 } 987 988 static struct file_system_type hostfs_type = { 989 .owner = THIS_MODULE, 990 .name = "hostfs", 991 .mount = hostfs_read_sb, 992 .kill_sb = hostfs_kill_sb, 993 .fs_flags = 0, 994 }; 995 MODULE_ALIAS_FS("hostfs"); 996 997 static int __init init_hostfs(void) 998 { 999 hostfs_inode_cache = KMEM_CACHE(hostfs_inode_info, 0); 1000 if (!hostfs_inode_cache) 1001 return -ENOMEM; 1002 return register_filesystem(&hostfs_type); 1003 } 1004 1005 static void __exit exit_hostfs(void) 1006 { 1007 unregister_filesystem(&hostfs_type); 1008 kmem_cache_destroy(hostfs_inode_cache); 1009 } 1010 1011 module_init(init_hostfs) 1012 module_exit(exit_hostfs) 1013 MODULE_LICENSE("GPL"); 1014