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