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 .splice_write = iter_file_splice_write, 385 .read_iter = generic_file_read_iter, 386 .write_iter = generic_file_write_iter, 387 .mmap = generic_file_mmap, 388 .open = hostfs_open, 389 .release = hostfs_file_release, 390 .fsync = hostfs_fsync, 391 }; 392 393 static const struct file_operations hostfs_dir_fops = { 394 .llseek = generic_file_llseek, 395 .iterate_shared = hostfs_readdir, 396 .read = generic_read_dir, 397 .open = hostfs_open, 398 .fsync = hostfs_fsync, 399 }; 400 401 static int hostfs_writepage(struct page *page, struct writeback_control *wbc) 402 { 403 struct address_space *mapping = page->mapping; 404 struct inode *inode = mapping->host; 405 char *buffer; 406 loff_t base = page_offset(page); 407 int count = PAGE_SIZE; 408 int end_index = inode->i_size >> PAGE_SHIFT; 409 int err; 410 411 if (page->index >= end_index) 412 count = inode->i_size & (PAGE_SIZE-1); 413 414 buffer = kmap(page); 415 416 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count); 417 if (err != count) { 418 ClearPageUptodate(page); 419 goto out; 420 } 421 422 if (base > inode->i_size) 423 inode->i_size = base; 424 425 if (PageError(page)) 426 ClearPageError(page); 427 err = 0; 428 429 out: 430 kunmap(page); 431 432 unlock_page(page); 433 return err; 434 } 435 436 static int hostfs_readpage(struct file *file, struct page *page) 437 { 438 char *buffer; 439 loff_t start = page_offset(page); 440 int bytes_read, ret = 0; 441 442 buffer = kmap(page); 443 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, 444 PAGE_SIZE); 445 if (bytes_read < 0) { 446 ClearPageUptodate(page); 447 SetPageError(page); 448 ret = bytes_read; 449 goto out; 450 } 451 452 memset(buffer + bytes_read, 0, PAGE_SIZE - bytes_read); 453 454 ClearPageError(page); 455 SetPageUptodate(page); 456 457 out: 458 flush_dcache_page(page); 459 kunmap(page); 460 unlock_page(page); 461 return ret; 462 } 463 464 static int hostfs_write_begin(struct file *file, struct address_space *mapping, 465 loff_t pos, unsigned len, unsigned flags, 466 struct page **pagep, void **fsdata) 467 { 468 pgoff_t index = pos >> PAGE_SHIFT; 469 470 *pagep = grab_cache_page_write_begin(mapping, index, flags); 471 if (!*pagep) 472 return -ENOMEM; 473 return 0; 474 } 475 476 static int hostfs_write_end(struct file *file, struct address_space *mapping, 477 loff_t pos, unsigned len, unsigned copied, 478 struct page *page, void *fsdata) 479 { 480 struct inode *inode = mapping->host; 481 void *buffer; 482 unsigned from = pos & (PAGE_SIZE - 1); 483 int err; 484 485 buffer = kmap(page); 486 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); 487 kunmap(page); 488 489 if (!PageUptodate(page) && err == PAGE_SIZE) 490 SetPageUptodate(page); 491 492 /* 493 * If err > 0, write_file has added err to pos, so we are comparing 494 * i_size against the last byte written. 495 */ 496 if (err > 0 && (pos > inode->i_size)) 497 inode->i_size = pos; 498 unlock_page(page); 499 put_page(page); 500 501 return err; 502 } 503 504 static const struct address_space_operations hostfs_aops = { 505 .writepage = hostfs_writepage, 506 .readpage = hostfs_readpage, 507 .set_page_dirty = __set_page_dirty_nobuffers, 508 .write_begin = hostfs_write_begin, 509 .write_end = hostfs_write_end, 510 }; 511 512 static int read_name(struct inode *ino, char *name) 513 { 514 dev_t rdev; 515 struct hostfs_stat st; 516 int err = stat_file(name, &st, -1); 517 if (err) 518 return err; 519 520 /* Reencode maj and min with the kernel encoding.*/ 521 rdev = MKDEV(st.maj, st.min); 522 523 switch (st.mode & S_IFMT) { 524 case S_IFLNK: 525 ino->i_op = &hostfs_link_iops; 526 break; 527 case S_IFDIR: 528 ino->i_op = &hostfs_dir_iops; 529 ino->i_fop = &hostfs_dir_fops; 530 break; 531 case S_IFCHR: 532 case S_IFBLK: 533 case S_IFIFO: 534 case S_IFSOCK: 535 init_special_inode(ino, st.mode & S_IFMT, rdev); 536 ino->i_op = &hostfs_iops; 537 break; 538 case S_IFREG: 539 ino->i_op = &hostfs_iops; 540 ino->i_fop = &hostfs_file_fops; 541 ino->i_mapping->a_ops = &hostfs_aops; 542 break; 543 default: 544 return -EIO; 545 } 546 547 ino->i_ino = st.ino; 548 ino->i_mode = st.mode; 549 set_nlink(ino, st.nlink); 550 i_uid_write(ino, st.uid); 551 i_gid_write(ino, st.gid); 552 ino->i_atime = (struct timespec64){ st.atime.tv_sec, st.atime.tv_nsec }; 553 ino->i_mtime = (struct timespec64){ st.mtime.tv_sec, st.mtime.tv_nsec }; 554 ino->i_ctime = (struct timespec64){ st.ctime.tv_sec, st.ctime.tv_nsec }; 555 ino->i_size = st.size; 556 ino->i_blocks = st.blocks; 557 return 0; 558 } 559 560 static int hostfs_create(struct user_namespace *mnt_userns, struct inode *dir, 561 struct dentry *dentry, umode_t mode, bool excl) 562 { 563 struct inode *inode; 564 char *name; 565 int error, fd; 566 567 inode = hostfs_iget(dir->i_sb); 568 if (IS_ERR(inode)) { 569 error = PTR_ERR(inode); 570 goto out; 571 } 572 573 error = -ENOMEM; 574 name = dentry_name(dentry); 575 if (name == NULL) 576 goto out_put; 577 578 fd = file_create(name, mode & 0777); 579 if (fd < 0) 580 error = fd; 581 else 582 error = read_name(inode, name); 583 584 __putname(name); 585 if (error) 586 goto out_put; 587 588 HOSTFS_I(inode)->fd = fd; 589 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; 590 d_instantiate(dentry, inode); 591 return 0; 592 593 out_put: 594 iput(inode); 595 out: 596 return error; 597 } 598 599 static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, 600 unsigned int flags) 601 { 602 struct inode *inode; 603 char *name; 604 int err; 605 606 inode = hostfs_iget(ino->i_sb); 607 if (IS_ERR(inode)) 608 goto out; 609 610 err = -ENOMEM; 611 name = dentry_name(dentry); 612 if (name) { 613 err = read_name(inode, name); 614 __putname(name); 615 } 616 if (err) { 617 iput(inode); 618 inode = (err == -ENOENT) ? NULL : ERR_PTR(err); 619 } 620 out: 621 return d_splice_alias(inode, dentry); 622 } 623 624 static int hostfs_link(struct dentry *to, struct inode *ino, 625 struct dentry *from) 626 { 627 char *from_name, *to_name; 628 int err; 629 630 if ((from_name = dentry_name(from)) == NULL) 631 return -ENOMEM; 632 to_name = dentry_name(to); 633 if (to_name == NULL) { 634 __putname(from_name); 635 return -ENOMEM; 636 } 637 err = link_file(to_name, from_name); 638 __putname(from_name); 639 __putname(to_name); 640 return err; 641 } 642 643 static int hostfs_unlink(struct inode *ino, struct dentry *dentry) 644 { 645 char *file; 646 int err; 647 648 if (append) 649 return -EPERM; 650 651 if ((file = dentry_name(dentry)) == NULL) 652 return -ENOMEM; 653 654 err = unlink_file(file); 655 __putname(file); 656 return err; 657 } 658 659 static int hostfs_symlink(struct user_namespace *mnt_userns, struct inode *ino, 660 struct dentry *dentry, const char *to) 661 { 662 char *file; 663 int err; 664 665 if ((file = dentry_name(dentry)) == NULL) 666 return -ENOMEM; 667 err = make_symlink(file, to); 668 __putname(file); 669 return err; 670 } 671 672 static int hostfs_mkdir(struct user_namespace *mnt_userns, struct inode *ino, 673 struct dentry *dentry, umode_t mode) 674 { 675 char *file; 676 int err; 677 678 if ((file = dentry_name(dentry)) == NULL) 679 return -ENOMEM; 680 err = do_mkdir(file, mode); 681 __putname(file); 682 return err; 683 } 684 685 static int hostfs_rmdir(struct inode *ino, struct dentry *dentry) 686 { 687 char *file; 688 int err; 689 690 if ((file = dentry_name(dentry)) == NULL) 691 return -ENOMEM; 692 err = hostfs_do_rmdir(file); 693 __putname(file); 694 return err; 695 } 696 697 static int hostfs_mknod(struct user_namespace *mnt_userns, struct inode *dir, 698 struct dentry *dentry, umode_t mode, dev_t dev) 699 { 700 struct inode *inode; 701 char *name; 702 int err; 703 704 inode = hostfs_iget(dir->i_sb); 705 if (IS_ERR(inode)) { 706 err = PTR_ERR(inode); 707 goto out; 708 } 709 710 err = -ENOMEM; 711 name = dentry_name(dentry); 712 if (name == NULL) 713 goto out_put; 714 715 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); 716 if (err) 717 goto out_free; 718 719 err = read_name(inode, name); 720 __putname(name); 721 if (err) 722 goto out_put; 723 724 d_instantiate(dentry, inode); 725 return 0; 726 727 out_free: 728 __putname(name); 729 out_put: 730 iput(inode); 731 out: 732 return err; 733 } 734 735 static int hostfs_rename2(struct user_namespace *mnt_userns, 736 struct inode *old_dir, struct dentry *old_dentry, 737 struct inode *new_dir, struct dentry *new_dentry, 738 unsigned int flags) 739 { 740 char *old_name, *new_name; 741 int err; 742 743 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) 744 return -EINVAL; 745 746 old_name = dentry_name(old_dentry); 747 if (old_name == NULL) 748 return -ENOMEM; 749 new_name = dentry_name(new_dentry); 750 if (new_name == NULL) { 751 __putname(old_name); 752 return -ENOMEM; 753 } 754 if (!flags) 755 err = rename_file(old_name, new_name); 756 else 757 err = rename2_file(old_name, new_name, flags); 758 759 __putname(old_name); 760 __putname(new_name); 761 return err; 762 } 763 764 static int hostfs_permission(struct user_namespace *mnt_userns, 765 struct inode *ino, int desired) 766 { 767 char *name; 768 int r = 0, w = 0, x = 0, err; 769 770 if (desired & MAY_NOT_BLOCK) 771 return -ECHILD; 772 773 if (desired & MAY_READ) r = 1; 774 if (desired & MAY_WRITE) w = 1; 775 if (desired & MAY_EXEC) x = 1; 776 name = inode_name(ino); 777 if (name == NULL) 778 return -ENOMEM; 779 780 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || 781 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) 782 err = 0; 783 else 784 err = access_file(name, r, w, x); 785 __putname(name); 786 if (!err) 787 err = generic_permission(&init_user_ns, ino, desired); 788 return err; 789 } 790 791 static int hostfs_setattr(struct user_namespace *mnt_userns, 792 struct dentry *dentry, struct iattr *attr) 793 { 794 struct inode *inode = d_inode(dentry); 795 struct hostfs_iattr attrs; 796 char *name; 797 int err; 798 799 int fd = HOSTFS_I(inode)->fd; 800 801 err = setattr_prepare(&init_user_ns, dentry, attr); 802 if (err) 803 return err; 804 805 if (append) 806 attr->ia_valid &= ~ATTR_SIZE; 807 808 attrs.ia_valid = 0; 809 if (attr->ia_valid & ATTR_MODE) { 810 attrs.ia_valid |= HOSTFS_ATTR_MODE; 811 attrs.ia_mode = attr->ia_mode; 812 } 813 if (attr->ia_valid & ATTR_UID) { 814 attrs.ia_valid |= HOSTFS_ATTR_UID; 815 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); 816 } 817 if (attr->ia_valid & ATTR_GID) { 818 attrs.ia_valid |= HOSTFS_ATTR_GID; 819 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); 820 } 821 if (attr->ia_valid & ATTR_SIZE) { 822 attrs.ia_valid |= HOSTFS_ATTR_SIZE; 823 attrs.ia_size = attr->ia_size; 824 } 825 if (attr->ia_valid & ATTR_ATIME) { 826 attrs.ia_valid |= HOSTFS_ATTR_ATIME; 827 attrs.ia_atime = (struct hostfs_timespec) 828 { attr->ia_atime.tv_sec, attr->ia_atime.tv_nsec }; 829 } 830 if (attr->ia_valid & ATTR_MTIME) { 831 attrs.ia_valid |= HOSTFS_ATTR_MTIME; 832 attrs.ia_mtime = (struct hostfs_timespec) 833 { attr->ia_mtime.tv_sec, attr->ia_mtime.tv_nsec }; 834 } 835 if (attr->ia_valid & ATTR_CTIME) { 836 attrs.ia_valid |= HOSTFS_ATTR_CTIME; 837 attrs.ia_ctime = (struct hostfs_timespec) 838 { attr->ia_ctime.tv_sec, attr->ia_ctime.tv_nsec }; 839 } 840 if (attr->ia_valid & ATTR_ATIME_SET) { 841 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; 842 } 843 if (attr->ia_valid & ATTR_MTIME_SET) { 844 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; 845 } 846 name = dentry_name(dentry); 847 if (name == NULL) 848 return -ENOMEM; 849 err = set_attr(name, &attrs, fd); 850 __putname(name); 851 if (err) 852 return err; 853 854 if ((attr->ia_valid & ATTR_SIZE) && 855 attr->ia_size != i_size_read(inode)) 856 truncate_setsize(inode, attr->ia_size); 857 858 setattr_copy(&init_user_ns, inode, attr); 859 mark_inode_dirty(inode); 860 return 0; 861 } 862 863 static const struct inode_operations hostfs_iops = { 864 .permission = hostfs_permission, 865 .setattr = hostfs_setattr, 866 }; 867 868 static const struct inode_operations hostfs_dir_iops = { 869 .create = hostfs_create, 870 .lookup = hostfs_lookup, 871 .link = hostfs_link, 872 .unlink = hostfs_unlink, 873 .symlink = hostfs_symlink, 874 .mkdir = hostfs_mkdir, 875 .rmdir = hostfs_rmdir, 876 .mknod = hostfs_mknod, 877 .rename = hostfs_rename2, 878 .permission = hostfs_permission, 879 .setattr = hostfs_setattr, 880 }; 881 882 static const char *hostfs_get_link(struct dentry *dentry, 883 struct inode *inode, 884 struct delayed_call *done) 885 { 886 char *link; 887 if (!dentry) 888 return ERR_PTR(-ECHILD); 889 link = kmalloc(PATH_MAX, GFP_KERNEL); 890 if (link) { 891 char *path = dentry_name(dentry); 892 int err = -ENOMEM; 893 if (path) { 894 err = hostfs_do_readlink(path, link, PATH_MAX); 895 if (err == PATH_MAX) 896 err = -E2BIG; 897 __putname(path); 898 } 899 if (err < 0) { 900 kfree(link); 901 return ERR_PTR(err); 902 } 903 } else { 904 return ERR_PTR(-ENOMEM); 905 } 906 907 set_delayed_call(done, kfree_link, link); 908 return link; 909 } 910 911 static const struct inode_operations hostfs_link_iops = { 912 .get_link = hostfs_get_link, 913 }; 914 915 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) 916 { 917 struct inode *root_inode; 918 char *host_root_path, *req_root = d; 919 int err; 920 921 sb->s_blocksize = 1024; 922 sb->s_blocksize_bits = 10; 923 sb->s_magic = HOSTFS_SUPER_MAGIC; 924 sb->s_op = &hostfs_sbops; 925 sb->s_d_op = &simple_dentry_operations; 926 sb->s_maxbytes = MAX_LFS_FILESIZE; 927 err = super_setup_bdi(sb); 928 if (err) 929 goto out; 930 931 /* NULL is printed as '(null)' by printf(): avoid that. */ 932 if (req_root == NULL) 933 req_root = ""; 934 935 err = -ENOMEM; 936 sb->s_fs_info = host_root_path = 937 kasprintf(GFP_KERNEL, "%s/%s", root_ino, req_root); 938 if (host_root_path == NULL) 939 goto out; 940 941 root_inode = new_inode(sb); 942 if (!root_inode) 943 goto out; 944 945 err = read_name(root_inode, host_root_path); 946 if (err) 947 goto out_put; 948 949 if (S_ISLNK(root_inode->i_mode)) { 950 char *name = follow_link(host_root_path); 951 if (IS_ERR(name)) { 952 err = PTR_ERR(name); 953 goto out_put; 954 } 955 err = read_name(root_inode, name); 956 kfree(name); 957 if (err) 958 goto out_put; 959 } 960 961 err = -ENOMEM; 962 sb->s_root = d_make_root(root_inode); 963 if (sb->s_root == NULL) 964 goto out; 965 966 return 0; 967 968 out_put: 969 iput(root_inode); 970 out: 971 return err; 972 } 973 974 static struct dentry *hostfs_read_sb(struct file_system_type *type, 975 int flags, const char *dev_name, 976 void *data) 977 { 978 return mount_nodev(type, flags, data, hostfs_fill_sb_common); 979 } 980 981 static void hostfs_kill_sb(struct super_block *s) 982 { 983 kill_anon_super(s); 984 kfree(s->s_fs_info); 985 } 986 987 static struct file_system_type hostfs_type = { 988 .owner = THIS_MODULE, 989 .name = "hostfs", 990 .mount = hostfs_read_sb, 991 .kill_sb = hostfs_kill_sb, 992 .fs_flags = 0, 993 }; 994 MODULE_ALIAS_FS("hostfs"); 995 996 static int __init init_hostfs(void) 997 { 998 hostfs_inode_cache = KMEM_CACHE(hostfs_inode_info, 0); 999 if (!hostfs_inode_cache) 1000 return -ENOMEM; 1001 return register_filesystem(&hostfs_type); 1002 } 1003 1004 static void __exit exit_hostfs(void) 1005 { 1006 unregister_filesystem(&hostfs_type); 1007 kmem_cache_destroy(hostfs_inode_cache); 1008 } 1009 1010 module_init(init_hostfs) 1011 module_exit(exit_hostfs) 1012 MODULE_LICENSE("GPL"); 1013