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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/fs_context.h>
20#include <linux/fs_parser.h>
21#include <linux/namei.h>
22#include "hostfs.h"
23#include <init.h>
24#include <kern.h>
25
26struct hostfs_fs_info {
27 char *host_root_path;
28};
29
30struct hostfs_inode_info {
31 int fd;
32 fmode_t mode;
33 struct inode vfs_inode;
34 struct mutex open_mutex;
35 dev_t dev;
36};
37
38static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
39{
40 return list_entry(inode, struct hostfs_inode_info, vfs_inode);
41}
42
43#define FILE_HOSTFS_I(file) HOSTFS_I(file_inode(file))
44
45static struct kmem_cache *hostfs_inode_cache;
46
47/* Changed in hostfs_args before the kernel starts running */
48static char *root_ino = "";
49static int append = 0;
50
51static const struct inode_operations hostfs_iops;
52static const struct inode_operations hostfs_dir_iops;
53static const struct inode_operations hostfs_link_iops;
54
55#ifndef MODULE
56static int __init hostfs_args(char *options, int *add)
57{
58 char *ptr;
59
60 *add = 0;
61 ptr = strchr(options, ',');
62 if (ptr != NULL)
63 *ptr++ = '\0';
64 if (*options != '\0')
65 root_ino = options;
66
67 options = ptr;
68 while (options) {
69 ptr = strchr(options, ',');
70 if (ptr != NULL)
71 *ptr++ = '\0';
72 if (*options != '\0') {
73 if (!strcmp(options, "append"))
74 append = 1;
75 else printf("hostfs_args - unsupported option - %s\n",
76 options);
77 }
78 options = ptr;
79 }
80 return 0;
81}
82
83__uml_setup("hostfs=", hostfs_args,
84"hostfs=<root dir>,<flags>,...\n"
85" This is used to set hostfs parameters. The root directory argument\n"
86" is used to confine all hostfs mounts to within the specified directory\n"
87" tree on the host. If this isn't specified, then a user inside UML can\n"
88" mount anything on the host that's accessible to the user that's running\n"
89" it.\n"
90" The only flag currently supported is 'append', which specifies that all\n"
91" files opened by hostfs will be opened in append mode.\n\n"
92);
93#endif
94
95static char *__dentry_name(struct dentry *dentry, char *name)
96{
97 char *p = dentry_path_raw(dentry, name, PATH_MAX);
98 struct hostfs_fs_info *fsi = dentry->d_sb->s_fs_info;
99 char *root = fsi->host_root_path;
100 size_t len = strlen(root);
101
102 if (IS_ERR(p) || len > p - name) {
103 __putname(name);
104 return NULL;
105 }
106
107 memcpy(name, root, len);
108 memmove(name + len, p, name + PATH_MAX - p);
109
110 return name;
111}
112
113static char *dentry_name(struct dentry *dentry)
114{
115 char *name = __getname();
116 if (!name)
117 return NULL;
118
119 return __dentry_name(dentry, name);
120}
121
122static char *inode_name(struct inode *ino)
123{
124 struct dentry *dentry;
125 char *name;
126
127 dentry = d_find_alias(ino);
128 if (!dentry)
129 return NULL;
130
131 name = dentry_name(dentry);
132
133 dput(dentry);
134
135 return name;
136}
137
138static char *follow_link(char *link)
139{
140 char *name, *resolved, *end;
141 int n;
142
143 name = kmalloc(PATH_MAX, GFP_KERNEL);
144 if (!name) {
145 n = -ENOMEM;
146 goto out_free;
147 }
148
149 n = hostfs_do_readlink(link, name, PATH_MAX);
150 if (n < 0)
151 goto out_free;
152 else if (n == PATH_MAX) {
153 n = -E2BIG;
154 goto out_free;
155 }
156
157 if (*name == '/')
158 return name;
159
160 end = strrchr(link, '/');
161 if (end == NULL)
162 return name;
163
164 *(end + 1) = '\0';
165
166 resolved = kasprintf(GFP_KERNEL, "%s%s", link, name);
167 if (resolved == NULL) {
168 n = -ENOMEM;
169 goto out_free;
170 }
171
172 kfree(name);
173 return resolved;
174
175 out_free:
176 kfree(name);
177 return ERR_PTR(n);
178}
179
180static int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
181{
182 /*
183 * do_statfs uses struct statfs64 internally, but the linux kernel
184 * struct statfs still has 32-bit versions for most of these fields,
185 * so we convert them here
186 */
187 int err;
188 long long f_blocks;
189 long long f_bfree;
190 long long f_bavail;
191 long long f_files;
192 long long f_ffree;
193 struct hostfs_fs_info *fsi;
194
195 fsi = dentry->d_sb->s_fs_info;
196 err = do_statfs(fsi->host_root_path,
197 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
198 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
199 &sf->f_namelen);
200 if (err)
201 return err;
202 sf->f_blocks = f_blocks;
203 sf->f_bfree = f_bfree;
204 sf->f_bavail = f_bavail;
205 sf->f_files = f_files;
206 sf->f_ffree = f_ffree;
207 sf->f_type = HOSTFS_SUPER_MAGIC;
208 return 0;
209}
210
211static struct inode *hostfs_alloc_inode(struct super_block *sb)
212{
213 struct hostfs_inode_info *hi;
214
215 hi = alloc_inode_sb(sb, hostfs_inode_cache, GFP_KERNEL_ACCOUNT);
216 if (hi == NULL)
217 return NULL;
218 hi->fd = -1;
219 hi->mode = 0;
220 hi->dev = 0;
221 inode_init_once(&hi->vfs_inode);
222 mutex_init(&hi->open_mutex);
223 return &hi->vfs_inode;
224}
225
226static void hostfs_evict_inode(struct inode *inode)
227{
228 truncate_inode_pages_final(&inode->i_data);
229 clear_inode(inode);
230 if (HOSTFS_I(inode)->fd != -1) {
231 close_file(&HOSTFS_I(inode)->fd);
232 HOSTFS_I(inode)->fd = -1;
233 HOSTFS_I(inode)->dev = 0;
234 }
235}
236
237static void hostfs_free_inode(struct inode *inode)
238{
239 kmem_cache_free(hostfs_inode_cache, HOSTFS_I(inode));
240}
241
242static int hostfs_show_options(struct seq_file *seq, struct dentry *root)
243{
244 struct hostfs_fs_info *fsi;
245 const char *root_path;
246
247 fsi = root->d_sb->s_fs_info;
248 root_path = fsi->host_root_path;
249 size_t offset = strlen(root_ino) + 1;
250
251 if (strlen(root_path) > offset)
252 seq_show_option(seq, root_path + offset, NULL);
253
254 if (append)
255 seq_puts(seq, ",append");
256
257 return 0;
258}
259
260static const struct super_operations hostfs_sbops = {
261 .alloc_inode = hostfs_alloc_inode,
262 .free_inode = hostfs_free_inode,
263 .drop_inode = generic_delete_inode,
264 .evict_inode = hostfs_evict_inode,
265 .statfs = hostfs_statfs,
266 .show_options = hostfs_show_options,
267};
268
269static int hostfs_readdir(struct file *file, struct dir_context *ctx)
270{
271 void *dir;
272 char *name;
273 unsigned long long next, ino;
274 int error, len;
275 unsigned int type;
276
277 name = dentry_name(file->f_path.dentry);
278 if (name == NULL)
279 return -ENOMEM;
280 dir = open_dir(name, &error);
281 __putname(name);
282 if (dir == NULL)
283 return -error;
284 next = ctx->pos;
285 seek_dir(dir, next);
286 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) {
287 if (!dir_emit(ctx, name, len, ino, type))
288 break;
289 ctx->pos = next;
290 }
291 close_dir(dir);
292 return 0;
293}
294
295static int hostfs_open(struct inode *ino, struct file *file)
296{
297 char *name;
298 fmode_t mode;
299 int err;
300 int r, w, fd;
301
302 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
303 if ((mode & HOSTFS_I(ino)->mode) == mode)
304 return 0;
305
306 mode |= HOSTFS_I(ino)->mode;
307
308retry:
309 r = w = 0;
310
311 if (mode & FMODE_READ)
312 r = 1;
313 if (mode & FMODE_WRITE)
314 r = w = 1;
315
316 name = dentry_name(file_dentry(file));
317 if (name == NULL)
318 return -ENOMEM;
319
320 fd = open_file(name, r, w, append);
321 __putname(name);
322 if (fd < 0)
323 return fd;
324
325 mutex_lock(&HOSTFS_I(ino)->open_mutex);
326 /* somebody else had handled it first? */
327 if ((mode & HOSTFS_I(ino)->mode) == mode) {
328 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
329 close_file(&fd);
330 return 0;
331 }
332 if ((mode | HOSTFS_I(ino)->mode) != mode) {
333 mode |= HOSTFS_I(ino)->mode;
334 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
335 close_file(&fd);
336 goto retry;
337 }
338 if (HOSTFS_I(ino)->fd == -1) {
339 HOSTFS_I(ino)->fd = fd;
340 } else {
341 err = replace_file(fd, HOSTFS_I(ino)->fd);
342 close_file(&fd);
343 if (err < 0) {
344 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
345 return err;
346 }
347 }
348 HOSTFS_I(ino)->mode = mode;
349 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
350
351 return 0;
352}
353
354static int hostfs_file_release(struct inode *inode, struct file *file)
355{
356 filemap_write_and_wait(inode->i_mapping);
357
358 return 0;
359}
360
361static int hostfs_fsync(struct file *file, loff_t start, loff_t end,
362 int datasync)
363{
364 struct inode *inode = file->f_mapping->host;
365 int ret;
366
367 ret = file_write_and_wait_range(file, start, end);
368 if (ret)
369 return ret;
370
371 inode_lock(inode);
372 ret = fsync_file(HOSTFS_I(inode)->fd, datasync);
373 inode_unlock(inode);
374
375 return ret;
376}
377
378static const struct file_operations hostfs_file_fops = {
379 .llseek = generic_file_llseek,
380 .splice_read = filemap_splice_read,
381 .splice_write = iter_file_splice_write,
382 .read_iter = generic_file_read_iter,
383 .write_iter = generic_file_write_iter,
384 .mmap = generic_file_mmap,
385 .open = hostfs_open,
386 .release = hostfs_file_release,
387 .fsync = hostfs_fsync,
388};
389
390static const struct file_operations hostfs_dir_fops = {
391 .llseek = generic_file_llseek,
392 .iterate_shared = hostfs_readdir,
393 .read = generic_read_dir,
394 .open = hostfs_open,
395 .fsync = hostfs_fsync,
396};
397
398static int hostfs_writepage(struct page *page, struct writeback_control *wbc)
399{
400 struct address_space *mapping = page->mapping;
401 struct inode *inode = mapping->host;
402 char *buffer;
403 loff_t base = page_offset(page);
404 int count = PAGE_SIZE;
405 int end_index = inode->i_size >> PAGE_SHIFT;
406 int err;
407
408 if (page->index >= end_index)
409 count = inode->i_size & (PAGE_SIZE-1);
410
411 buffer = kmap_local_page(page);
412
413 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
414 if (err != count) {
415 if (err >= 0)
416 err = -EIO;
417 mapping_set_error(mapping, err);
418 goto out;
419 }
420
421 if (base > inode->i_size)
422 inode->i_size = base;
423
424 err = 0;
425
426 out:
427 kunmap_local(buffer);
428 unlock_page(page);
429
430 return err;
431}
432
433static int hostfs_read_folio(struct file *file, struct folio *folio)
434{
435 char *buffer;
436 loff_t start = folio_pos(folio);
437 int bytes_read, ret = 0;
438
439 buffer = kmap_local_folio(folio, 0);
440 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
441 PAGE_SIZE);
442 if (bytes_read < 0)
443 ret = bytes_read;
444 else
445 buffer = folio_zero_tail(folio, bytes_read, buffer + bytes_read);
446 kunmap_local(buffer);
447
448 folio_end_read(folio, ret == 0);
449 return ret;
450}
451
452static int hostfs_write_begin(struct file *file, struct address_space *mapping,
453 loff_t pos, unsigned len,
454 struct folio **foliop, void **fsdata)
455{
456 pgoff_t index = pos >> PAGE_SHIFT;
457
458 *foliop = __filemap_get_folio(mapping, index, FGP_WRITEBEGIN,
459 mapping_gfp_mask(mapping));
460 if (IS_ERR(*foliop))
461 return PTR_ERR(*foliop);
462 return 0;
463}
464
465static int hostfs_write_end(struct file *file, struct address_space *mapping,
466 loff_t pos, unsigned len, unsigned copied,
467 struct folio *folio, void *fsdata)
468{
469 struct inode *inode = mapping->host;
470 void *buffer;
471 size_t from = offset_in_folio(folio, pos);
472 int err;
473
474 buffer = kmap_local_folio(folio, from);
475 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer, copied);
476 kunmap_local(buffer);
477
478 if (!folio_test_uptodate(folio) && err == folio_size(folio))
479 folio_mark_uptodate(folio);
480
481 /*
482 * If err > 0, write_file has added err to pos, so we are comparing
483 * i_size against the last byte written.
484 */
485 if (err > 0 && (pos > inode->i_size))
486 inode->i_size = pos;
487 folio_unlock(folio);
488 folio_put(folio);
489
490 return err;
491}
492
493static const struct address_space_operations hostfs_aops = {
494 .writepage = hostfs_writepage,
495 .read_folio = hostfs_read_folio,
496 .dirty_folio = filemap_dirty_folio,
497 .write_begin = hostfs_write_begin,
498 .write_end = hostfs_write_end,
499};
500
501static int hostfs_inode_update(struct inode *ino, const struct hostfs_stat *st)
502{
503 set_nlink(ino, st->nlink);
504 i_uid_write(ino, st->uid);
505 i_gid_write(ino, st->gid);
506 inode_set_atime_to_ts(ino, (struct timespec64){
507 st->atime.tv_sec,
508 st->atime.tv_nsec,
509 });
510 inode_set_mtime_to_ts(ino, (struct timespec64){
511 st->mtime.tv_sec,
512 st->mtime.tv_nsec,
513 });
514 inode_set_ctime(ino, st->ctime.tv_sec, st->ctime.tv_nsec);
515 ino->i_size = st->size;
516 ino->i_blocks = st->blocks;
517 return 0;
518}
519
520static int hostfs_inode_set(struct inode *ino, void *data)
521{
522 struct hostfs_stat *st = data;
523 dev_t dev, rdev;
524
525 /* Reencode maj and min with the kernel encoding.*/
526 rdev = MKDEV(st->rdev.maj, st->rdev.min);
527 dev = MKDEV(st->dev.maj, st->dev.min);
528
529 switch (st->mode & S_IFMT) {
530 case S_IFLNK:
531 ino->i_op = &hostfs_link_iops;
532 break;
533 case S_IFDIR:
534 ino->i_op = &hostfs_dir_iops;
535 ino->i_fop = &hostfs_dir_fops;
536 break;
537 case S_IFCHR:
538 case S_IFBLK:
539 case S_IFIFO:
540 case S_IFSOCK:
541 init_special_inode(ino, st->mode & S_IFMT, rdev);
542 ino->i_op = &hostfs_iops;
543 break;
544 case S_IFREG:
545 ino->i_op = &hostfs_iops;
546 ino->i_fop = &hostfs_file_fops;
547 ino->i_mapping->a_ops = &hostfs_aops;
548 break;
549 default:
550 return -EIO;
551 }
552
553 HOSTFS_I(ino)->dev = dev;
554 ino->i_ino = st->ino;
555 ino->i_mode = st->mode;
556 return hostfs_inode_update(ino, st);
557}
558
559static int hostfs_inode_test(struct inode *inode, void *data)
560{
561 const struct hostfs_stat *st = data;
562 dev_t dev = MKDEV(st->dev.maj, st->dev.min);
563
564 return inode->i_ino == st->ino && HOSTFS_I(inode)->dev == dev;
565}
566
567static struct inode *hostfs_iget(struct super_block *sb, char *name)
568{
569 struct inode *inode;
570 struct hostfs_stat st;
571 int err = stat_file(name, &st, -1);
572
573 if (err)
574 return ERR_PTR(err);
575
576 inode = iget5_locked(sb, st.ino, hostfs_inode_test, hostfs_inode_set,
577 &st);
578 if (!inode)
579 return ERR_PTR(-ENOMEM);
580
581 if (inode->i_state & I_NEW) {
582 unlock_new_inode(inode);
583 } else {
584 spin_lock(&inode->i_lock);
585 hostfs_inode_update(inode, &st);
586 spin_unlock(&inode->i_lock);
587 }
588
589 return inode;
590}
591
592static int hostfs_create(struct mnt_idmap *idmap, struct inode *dir,
593 struct dentry *dentry, umode_t mode, bool excl)
594{
595 struct inode *inode;
596 char *name;
597 int fd;
598
599 name = dentry_name(dentry);
600 if (name == NULL)
601 return -ENOMEM;
602
603 fd = file_create(name, mode & 0777);
604 if (fd < 0) {
605 __putname(name);
606 return fd;
607 }
608
609 inode = hostfs_iget(dir->i_sb, name);
610 __putname(name);
611 if (IS_ERR(inode))
612 return PTR_ERR(inode);
613
614 HOSTFS_I(inode)->fd = fd;
615 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
616 d_instantiate(dentry, inode);
617 return 0;
618}
619
620static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
621 unsigned int flags)
622{
623 struct inode *inode = NULL;
624 char *name;
625
626 name = dentry_name(dentry);
627 if (name == NULL)
628 return ERR_PTR(-ENOMEM);
629
630 inode = hostfs_iget(ino->i_sb, name);
631 __putname(name);
632 if (inode == ERR_PTR(-ENOENT))
633 inode = NULL;
634
635 return d_splice_alias(inode, dentry);
636}
637
638static int hostfs_link(struct dentry *to, struct inode *ino,
639 struct dentry *from)
640{
641 char *from_name, *to_name;
642 int err;
643
644 if ((from_name = dentry_name(from)) == NULL)
645 return -ENOMEM;
646 to_name = dentry_name(to);
647 if (to_name == NULL) {
648 __putname(from_name);
649 return -ENOMEM;
650 }
651 err = link_file(to_name, from_name);
652 __putname(from_name);
653 __putname(to_name);
654 return err;
655}
656
657static int hostfs_unlink(struct inode *ino, struct dentry *dentry)
658{
659 char *file;
660 int err;
661
662 if (append)
663 return -EPERM;
664
665 if ((file = dentry_name(dentry)) == NULL)
666 return -ENOMEM;
667
668 err = unlink_file(file);
669 __putname(file);
670 return err;
671}
672
673static int hostfs_symlink(struct mnt_idmap *idmap, struct inode *ino,
674 struct dentry *dentry, const char *to)
675{
676 char *file;
677 int err;
678
679 if ((file = dentry_name(dentry)) == NULL)
680 return -ENOMEM;
681 err = make_symlink(file, to);
682 __putname(file);
683 return err;
684}
685
686static int hostfs_mkdir(struct mnt_idmap *idmap, struct inode *ino,
687 struct dentry *dentry, umode_t mode)
688{
689 char *file;
690 int err;
691
692 if ((file = dentry_name(dentry)) == NULL)
693 return -ENOMEM;
694 err = do_mkdir(file, mode);
695 __putname(file);
696 return err;
697}
698
699static int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
700{
701 char *file;
702 int err;
703
704 if ((file = dentry_name(dentry)) == NULL)
705 return -ENOMEM;
706 err = hostfs_do_rmdir(file);
707 __putname(file);
708 return err;
709}
710
711static int hostfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
712 struct dentry *dentry, umode_t mode, dev_t dev)
713{
714 struct inode *inode;
715 char *name;
716 int err;
717
718 name = dentry_name(dentry);
719 if (name == NULL)
720 return -ENOMEM;
721
722 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
723 if (err) {
724 __putname(name);
725 return err;
726 }
727
728 inode = hostfs_iget(dir->i_sb, name);
729 __putname(name);
730 if (IS_ERR(inode))
731 return PTR_ERR(inode);
732
733 d_instantiate(dentry, inode);
734 return 0;
735}
736
737static int hostfs_rename2(struct mnt_idmap *idmap,
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
766static int hostfs_permission(struct mnt_idmap *idmap,
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(&nop_mnt_idmap, ino, desired);
790 return err;
791}
792
793static int hostfs_setattr(struct mnt_idmap *idmap,
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(&nop_mnt_idmap, 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(&nop_mnt_idmap, inode, attr);
861 mark_inode_dirty(inode);
862 return 0;
863}
864
865static const struct inode_operations hostfs_iops = {
866 .permission = hostfs_permission,
867 .setattr = hostfs_setattr,
868};
869
870static 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
884static 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
913static const struct inode_operations hostfs_link_iops = {
914 .get_link = hostfs_get_link,
915};
916
917static int hostfs_fill_super(struct super_block *sb, struct fs_context *fc)
918{
919 struct hostfs_fs_info *fsi = sb->s_fs_info;
920 struct inode *root_inode;
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 return err;
932
933 root_inode = hostfs_iget(sb, fsi->host_root_path);
934 if (IS_ERR(root_inode))
935 return PTR_ERR(root_inode);
936
937 if (S_ISLNK(root_inode->i_mode)) {
938 char *name;
939
940 iput(root_inode);
941 name = follow_link(fsi->host_root_path);
942 if (IS_ERR(name))
943 return PTR_ERR(name);
944
945 root_inode = hostfs_iget(sb, name);
946 kfree(name);
947 if (IS_ERR(root_inode))
948 return PTR_ERR(root_inode);
949 }
950
951 sb->s_root = d_make_root(root_inode);
952 if (sb->s_root == NULL)
953 return -ENOMEM;
954
955 return 0;
956}
957
958enum hostfs_parma {
959 Opt_hostfs,
960};
961
962static const struct fs_parameter_spec hostfs_param_specs[] = {
963 fsparam_string_empty("hostfs", Opt_hostfs),
964 {}
965};
966
967static int hostfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
968{
969 struct hostfs_fs_info *fsi = fc->s_fs_info;
970 struct fs_parse_result result;
971 char *host_root;
972 int opt;
973
974 opt = fs_parse(fc, hostfs_param_specs, param, &result);
975 if (opt < 0)
976 return opt;
977
978 switch (opt) {
979 case Opt_hostfs:
980 host_root = param->string;
981 if (!*host_root)
982 host_root = "";
983 fsi->host_root_path =
984 kasprintf(GFP_KERNEL, "%s/%s", root_ino, host_root);
985 if (fsi->host_root_path == NULL)
986 return -ENOMEM;
987 break;
988 }
989
990 return 0;
991}
992
993static int hostfs_parse_monolithic(struct fs_context *fc, void *data)
994{
995 struct hostfs_fs_info *fsi = fc->s_fs_info;
996 char *host_root = (char *)data;
997
998 /* NULL is printed as '(null)' by printf(): avoid that. */
999 if (host_root == NULL)
1000 host_root = "";
1001
1002 fsi->host_root_path =
1003 kasprintf(GFP_KERNEL, "%s/%s", root_ino, host_root);
1004 if (fsi->host_root_path == NULL)
1005 return -ENOMEM;
1006
1007 return 0;
1008}
1009
1010static int hostfs_fc_get_tree(struct fs_context *fc)
1011{
1012 return get_tree_nodev(fc, hostfs_fill_super);
1013}
1014
1015static void hostfs_fc_free(struct fs_context *fc)
1016{
1017 struct hostfs_fs_info *fsi = fc->s_fs_info;
1018
1019 if (!fsi)
1020 return;
1021
1022 kfree(fsi->host_root_path);
1023 kfree(fsi);
1024}
1025
1026static const struct fs_context_operations hostfs_context_ops = {
1027 .parse_monolithic = hostfs_parse_monolithic,
1028 .parse_param = hostfs_parse_param,
1029 .get_tree = hostfs_fc_get_tree,
1030 .free = hostfs_fc_free,
1031};
1032
1033static int hostfs_init_fs_context(struct fs_context *fc)
1034{
1035 struct hostfs_fs_info *fsi;
1036
1037 fsi = kzalloc(sizeof(*fsi), GFP_KERNEL);
1038 if (!fsi)
1039 return -ENOMEM;
1040
1041 fc->s_fs_info = fsi;
1042 fc->ops = &hostfs_context_ops;
1043 return 0;
1044}
1045
1046static void hostfs_kill_sb(struct super_block *s)
1047{
1048 kill_anon_super(s);
1049 kfree(s->s_fs_info);
1050}
1051
1052static struct file_system_type hostfs_type = {
1053 .owner = THIS_MODULE,
1054 .name = "hostfs",
1055 .init_fs_context = hostfs_init_fs_context,
1056 .kill_sb = hostfs_kill_sb,
1057 .fs_flags = 0,
1058};
1059MODULE_ALIAS_FS("hostfs");
1060
1061static int __init init_hostfs(void)
1062{
1063 hostfs_inode_cache = KMEM_CACHE(hostfs_inode_info, 0);
1064 if (!hostfs_inode_cache)
1065 return -ENOMEM;
1066 return register_filesystem(&hostfs_type);
1067}
1068
1069static void __exit exit_hostfs(void)
1070{
1071 unregister_filesystem(&hostfs_type);
1072 kmem_cache_destroy(hostfs_inode_cache);
1073}
1074
1075module_init(init_hostfs)
1076module_exit(exit_hostfs)
1077MODULE_DESCRIPTION("User-Mode Linux Host filesystem");
1078MODULE_LICENSE("GPL");
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
23struct hostfs_inode_info {
24 int fd;
25 fmode_t mode;
26 struct inode vfs_inode;
27};
28
29static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
30{
31 return list_entry(inode, struct hostfs_inode_info, vfs_inode);
32}
33
34#define FILE_HOSTFS_I(file) HOSTFS_I(file_inode(file))
35
36/* Changed in hostfs_args before the kernel starts running */
37static char *root_ino = "";
38static int append = 0;
39
40static const struct inode_operations hostfs_iops;
41static const struct inode_operations hostfs_dir_iops;
42static const struct inode_operations hostfs_link_iops;
43
44#ifndef MODULE
45static int __init hostfs_args(char *options, int *add)
46{
47 char *ptr;
48
49 ptr = strchr(options, ',');
50 if (ptr != NULL)
51 *ptr++ = '\0';
52 if (*options != '\0')
53 root_ino = options;
54
55 options = ptr;
56 while (options) {
57 ptr = strchr(options, ',');
58 if (ptr != NULL)
59 *ptr++ = '\0';
60 if (*options != '\0') {
61 if (!strcmp(options, "append"))
62 append = 1;
63 else printf("hostfs_args - unsupported option - %s\n",
64 options);
65 }
66 options = ptr;
67 }
68 return 0;
69}
70
71__uml_setup("hostfs=", hostfs_args,
72"hostfs=<root dir>,<flags>,...\n"
73" This is used to set hostfs parameters. The root directory argument\n"
74" is used to confine all hostfs mounts to within the specified directory\n"
75" tree on the host. If this isn't specified, then a user inside UML can\n"
76" mount anything on the host that's accessible to the user that's running\n"
77" it.\n"
78" The only flag currently supported is 'append', which specifies that all\n"
79" files opened by hostfs will be opened in append mode.\n\n"
80);
81#endif
82
83static char *__dentry_name(struct dentry *dentry, char *name)
84{
85 char *p = dentry_path_raw(dentry, name, PATH_MAX);
86 char *root;
87 size_t len;
88
89 root = dentry->d_sb->s_fs_info;
90 len = strlen(root);
91 if (IS_ERR(p)) {
92 __putname(name);
93 return NULL;
94 }
95 strlcpy(name, root, PATH_MAX);
96 if (len > p - name) {
97 __putname(name);
98 return NULL;
99 }
100 if (p > name + len) {
101 char *s = name + len;
102 while ((*s++ = *p++) != '\0')
103 ;
104 }
105 return name;
106}
107
108static char *dentry_name(struct dentry *dentry)
109{
110 char *name = __getname();
111 if (!name)
112 return NULL;
113
114 return __dentry_name(dentry, name);
115}
116
117static char *inode_name(struct inode *ino)
118{
119 struct dentry *dentry;
120 char *name;
121
122 dentry = d_find_alias(ino);
123 if (!dentry)
124 return NULL;
125
126 name = dentry_name(dentry);
127
128 dput(dentry);
129
130 return name;
131}
132
133static char *follow_link(char *link)
134{
135 int len, n;
136 char *name, *resolved, *end;
137
138 len = 64;
139 while (1) {
140 n = -ENOMEM;
141 name = kmalloc(len, GFP_KERNEL);
142 if (name == NULL)
143 goto out;
144
145 n = hostfs_do_readlink(link, name, len);
146 if (n < len)
147 break;
148 len *= 2;
149 kfree(name);
150 }
151 if (n < 0)
152 goto out_free;
153
154 if (*name == '/')
155 return name;
156
157 end = strrchr(link, '/');
158 if (end == NULL)
159 return name;
160
161 *(end + 1) = '\0';
162 len = strlen(link) + strlen(name) + 1;
163
164 resolved = kmalloc(len, GFP_KERNEL);
165 if (resolved == NULL) {
166 n = -ENOMEM;
167 goto out_free;
168 }
169
170 sprintf(resolved, "%s%s", link, name);
171 kfree(name);
172 kfree(link);
173 return resolved;
174
175 out_free:
176 kfree(name);
177 out:
178 return ERR_PTR(n);
179}
180
181static struct inode *hostfs_iget(struct super_block *sb)
182{
183 struct inode *inode = new_inode(sb);
184 if (!inode)
185 return ERR_PTR(-ENOMEM);
186 return inode;
187}
188
189static int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
190{
191 /*
192 * do_statfs uses struct statfs64 internally, but the linux kernel
193 * struct statfs still has 32-bit versions for most of these fields,
194 * so we convert them here
195 */
196 int err;
197 long long f_blocks;
198 long long f_bfree;
199 long long f_bavail;
200 long long f_files;
201 long long f_ffree;
202
203 err = do_statfs(dentry->d_sb->s_fs_info,
204 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
205 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
206 &sf->f_namelen);
207 if (err)
208 return err;
209 sf->f_blocks = f_blocks;
210 sf->f_bfree = f_bfree;
211 sf->f_bavail = f_bavail;
212 sf->f_files = f_files;
213 sf->f_ffree = f_ffree;
214 sf->f_type = HOSTFS_SUPER_MAGIC;
215 return 0;
216}
217
218static struct inode *hostfs_alloc_inode(struct super_block *sb)
219{
220 struct hostfs_inode_info *hi;
221
222 hi = kmalloc(sizeof(*hi), GFP_KERNEL);
223 if (hi == NULL)
224 return NULL;
225 hi->fd = -1;
226 hi->mode = 0;
227 inode_init_once(&hi->vfs_inode);
228 return &hi->vfs_inode;
229}
230
231static void hostfs_evict_inode(struct inode *inode)
232{
233 truncate_inode_pages_final(&inode->i_data);
234 clear_inode(inode);
235 if (HOSTFS_I(inode)->fd != -1) {
236 close_file(&HOSTFS_I(inode)->fd);
237 HOSTFS_I(inode)->fd = -1;
238 }
239}
240
241static void hostfs_i_callback(struct rcu_head *head)
242{
243 struct inode *inode = container_of(head, struct inode, i_rcu);
244 kfree(HOSTFS_I(inode));
245}
246
247static void hostfs_destroy_inode(struct inode *inode)
248{
249 call_rcu(&inode->i_rcu, hostfs_i_callback);
250}
251
252static int hostfs_show_options(struct seq_file *seq, struct dentry *root)
253{
254 const char *root_path = root->d_sb->s_fs_info;
255 size_t offset = strlen(root_ino) + 1;
256
257 if (strlen(root_path) > offset)
258 seq_printf(seq, ",%s", root_path + offset);
259
260 return 0;
261}
262
263static const struct super_operations hostfs_sbops = {
264 .alloc_inode = hostfs_alloc_inode,
265 .destroy_inode = hostfs_destroy_inode,
266 .evict_inode = hostfs_evict_inode,
267 .statfs = hostfs_statfs,
268 .show_options = hostfs_show_options,
269};
270
271static int hostfs_readdir(struct file *file, struct dir_context *ctx)
272{
273 void *dir;
274 char *name;
275 unsigned long long next, ino;
276 int error, len;
277 unsigned int type;
278
279 name = dentry_name(file->f_path.dentry);
280 if (name == NULL)
281 return -ENOMEM;
282 dir = open_dir(name, &error);
283 __putname(name);
284 if (dir == NULL)
285 return -error;
286 next = ctx->pos;
287 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) {
288 if (!dir_emit(ctx, name, len, ino, type))
289 break;
290 ctx->pos = next;
291 }
292 close_dir(dir);
293 return 0;
294}
295
296static int hostfs_file_open(struct inode *ino, struct file *file)
297{
298 static DEFINE_MUTEX(open_mutex);
299 char *name;
300 fmode_t mode = 0;
301 int err;
302 int r = 0, w = 0, fd;
303
304 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
305 if ((mode & HOSTFS_I(ino)->mode) == mode)
306 return 0;
307
308 mode |= HOSTFS_I(ino)->mode;
309
310retry:
311 if (mode & FMODE_READ)
312 r = 1;
313 if (mode & FMODE_WRITE)
314 w = 1;
315 if (w)
316 r = 1;
317
318 name = dentry_name(file->f_path.dentry);
319 if (name == NULL)
320 return -ENOMEM;
321
322 fd = open_file(name, r, w, append);
323 __putname(name);
324 if (fd < 0)
325 return fd;
326
327 mutex_lock(&open_mutex);
328 /* somebody else had handled it first? */
329 if ((mode & HOSTFS_I(ino)->mode) == mode) {
330 mutex_unlock(&open_mutex);
331 return 0;
332 }
333 if ((mode | HOSTFS_I(ino)->mode) != mode) {
334 mode |= HOSTFS_I(ino)->mode;
335 mutex_unlock(&open_mutex);
336 close_file(&fd);
337 goto retry;
338 }
339 if (HOSTFS_I(ino)->fd == -1) {
340 HOSTFS_I(ino)->fd = fd;
341 } else {
342 err = replace_file(fd, HOSTFS_I(ino)->fd);
343 close_file(&fd);
344 if (err < 0) {
345 mutex_unlock(&open_mutex);
346 return err;
347 }
348 }
349 HOSTFS_I(ino)->mode = mode;
350 mutex_unlock(&open_mutex);
351
352 return 0;
353}
354
355static int hostfs_file_release(struct inode *inode, struct file *file)
356{
357 filemap_write_and_wait(inode->i_mapping);
358
359 return 0;
360}
361
362static int hostfs_fsync(struct file *file, loff_t start, loff_t end,
363 int datasync)
364{
365 struct inode *inode = file->f_mapping->host;
366 int ret;
367
368 ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
369 if (ret)
370 return ret;
371
372 mutex_lock(&inode->i_mutex);
373 ret = fsync_file(HOSTFS_I(inode)->fd, datasync);
374 mutex_unlock(&inode->i_mutex);
375
376 return ret;
377}
378
379static const struct file_operations hostfs_file_fops = {
380 .llseek = generic_file_llseek,
381 .read = do_sync_read,
382 .splice_read = generic_file_splice_read,
383 .aio_read = generic_file_aio_read,
384 .aio_write = generic_file_aio_write,
385 .write = do_sync_write,
386 .mmap = generic_file_mmap,
387 .open = hostfs_file_open,
388 .release = hostfs_file_release,
389 .fsync = hostfs_fsync,
390};
391
392static const struct file_operations hostfs_dir_fops = {
393 .llseek = generic_file_llseek,
394 .iterate = hostfs_readdir,
395 .read = generic_read_dir,
396};
397
398static int hostfs_writepage(struct page *page, struct writeback_control *wbc)
399{
400 struct address_space *mapping = page->mapping;
401 struct inode *inode = mapping->host;
402 char *buffer;
403 unsigned long long base;
404 int count = PAGE_CACHE_SIZE;
405 int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
406 int err;
407
408 if (page->index >= end_index)
409 count = inode->i_size & (PAGE_CACHE_SIZE-1);
410
411 buffer = kmap(page);
412 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
413
414 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
415 if (err != count) {
416 ClearPageUptodate(page);
417 goto out;
418 }
419
420 if (base > inode->i_size)
421 inode->i_size = base;
422
423 if (PageError(page))
424 ClearPageError(page);
425 err = 0;
426
427 out:
428 kunmap(page);
429
430 unlock_page(page);
431 return err;
432}
433
434static int hostfs_readpage(struct file *file, struct page *page)
435{
436 char *buffer;
437 long long start;
438 int err = 0;
439
440 start = (long long) page->index << PAGE_CACHE_SHIFT;
441 buffer = kmap(page);
442 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
443 PAGE_CACHE_SIZE);
444 if (err < 0)
445 goto out;
446
447 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
448
449 flush_dcache_page(page);
450 SetPageUptodate(page);
451 if (PageError(page)) ClearPageError(page);
452 err = 0;
453 out:
454 kunmap(page);
455 unlock_page(page);
456 return err;
457}
458
459static int hostfs_write_begin(struct file *file, struct address_space *mapping,
460 loff_t pos, unsigned len, unsigned flags,
461 struct page **pagep, void **fsdata)
462{
463 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
464
465 *pagep = grab_cache_page_write_begin(mapping, index, flags);
466 if (!*pagep)
467 return -ENOMEM;
468 return 0;
469}
470
471static int hostfs_write_end(struct file *file, struct address_space *mapping,
472 loff_t pos, unsigned len, unsigned copied,
473 struct page *page, void *fsdata)
474{
475 struct inode *inode = mapping->host;
476 void *buffer;
477 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
478 int err;
479
480 buffer = kmap(page);
481 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
482 kunmap(page);
483
484 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE)
485 SetPageUptodate(page);
486
487 /*
488 * If err > 0, write_file has added err to pos, so we are comparing
489 * i_size against the last byte written.
490 */
491 if (err > 0 && (pos > inode->i_size))
492 inode->i_size = pos;
493 unlock_page(page);
494 page_cache_release(page);
495
496 return err;
497}
498
499static const struct address_space_operations hostfs_aops = {
500 .writepage = hostfs_writepage,
501 .readpage = hostfs_readpage,
502 .set_page_dirty = __set_page_dirty_nobuffers,
503 .write_begin = hostfs_write_begin,
504 .write_end = hostfs_write_end,
505};
506
507static int read_name(struct inode *ino, char *name)
508{
509 dev_t rdev;
510 struct hostfs_stat st;
511 int err = stat_file(name, &st, -1);
512 if (err)
513 return err;
514
515 /* Reencode maj and min with the kernel encoding.*/
516 rdev = MKDEV(st.maj, st.min);
517
518 switch (st.mode & S_IFMT) {
519 case S_IFLNK:
520 ino->i_op = &hostfs_link_iops;
521 break;
522 case S_IFDIR:
523 ino->i_op = &hostfs_dir_iops;
524 ino->i_fop = &hostfs_dir_fops;
525 break;
526 case S_IFCHR:
527 case S_IFBLK:
528 case S_IFIFO:
529 case S_IFSOCK:
530 init_special_inode(ino, st.mode & S_IFMT, rdev);
531 ino->i_op = &hostfs_iops;
532 break;
533
534 default:
535 ino->i_op = &hostfs_iops;
536 ino->i_fop = &hostfs_file_fops;
537 ino->i_mapping->a_ops = &hostfs_aops;
538 }
539
540 ino->i_ino = st.ino;
541 ino->i_mode = st.mode;
542 set_nlink(ino, st.nlink);
543 i_uid_write(ino, st.uid);
544 i_gid_write(ino, st.gid);
545 ino->i_atime = st.atime;
546 ino->i_mtime = st.mtime;
547 ino->i_ctime = st.ctime;
548 ino->i_size = st.size;
549 ino->i_blocks = st.blocks;
550 return 0;
551}
552
553static int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
554 bool excl)
555{
556 struct inode *inode;
557 char *name;
558 int error, fd;
559
560 inode = hostfs_iget(dir->i_sb);
561 if (IS_ERR(inode)) {
562 error = PTR_ERR(inode);
563 goto out;
564 }
565
566 error = -ENOMEM;
567 name = dentry_name(dentry);
568 if (name == NULL)
569 goto out_put;
570
571 fd = file_create(name,
572 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
573 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
574 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
575 if (fd < 0)
576 error = fd;
577 else
578 error = read_name(inode, name);
579
580 __putname(name);
581 if (error)
582 goto out_put;
583
584 HOSTFS_I(inode)->fd = fd;
585 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
586 d_instantiate(dentry, inode);
587 return 0;
588
589 out_put:
590 iput(inode);
591 out:
592 return error;
593}
594
595static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
596 unsigned int flags)
597{
598 struct inode *inode;
599 char *name;
600 int err;
601
602 inode = hostfs_iget(ino->i_sb);
603 if (IS_ERR(inode)) {
604 err = PTR_ERR(inode);
605 goto out;
606 }
607
608 err = -ENOMEM;
609 name = dentry_name(dentry);
610 if (name == NULL)
611 goto out_put;
612
613 err = read_name(inode, name);
614
615 __putname(name);
616 if (err == -ENOENT) {
617 iput(inode);
618 inode = NULL;
619 }
620 else if (err)
621 goto out_put;
622
623 d_add(dentry, inode);
624 return NULL;
625
626 out_put:
627 iput(inode);
628 out:
629 return ERR_PTR(err);
630}
631
632static int hostfs_link(struct dentry *to, struct inode *ino,
633 struct dentry *from)
634{
635 char *from_name, *to_name;
636 int err;
637
638 if ((from_name = dentry_name(from)) == NULL)
639 return -ENOMEM;
640 to_name = dentry_name(to);
641 if (to_name == NULL) {
642 __putname(from_name);
643 return -ENOMEM;
644 }
645 err = link_file(to_name, from_name);
646 __putname(from_name);
647 __putname(to_name);
648 return err;
649}
650
651static int hostfs_unlink(struct inode *ino, struct dentry *dentry)
652{
653 char *file;
654 int err;
655
656 if (append)
657 return -EPERM;
658
659 if ((file = dentry_name(dentry)) == NULL)
660 return -ENOMEM;
661
662 err = unlink_file(file);
663 __putname(file);
664 return err;
665}
666
667static int hostfs_symlink(struct inode *ino, struct dentry *dentry,
668 const char *to)
669{
670 char *file;
671 int err;
672
673 if ((file = dentry_name(dentry)) == NULL)
674 return -ENOMEM;
675 err = make_symlink(file, to);
676 __putname(file);
677 return err;
678}
679
680static int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode)
681{
682 char *file;
683 int err;
684
685 if ((file = dentry_name(dentry)) == NULL)
686 return -ENOMEM;
687 err = do_mkdir(file, mode);
688 __putname(file);
689 return err;
690}
691
692static int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
693{
694 char *file;
695 int err;
696
697 if ((file = dentry_name(dentry)) == NULL)
698 return -ENOMEM;
699 err = do_rmdir(file);
700 __putname(file);
701 return err;
702}
703
704static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
705{
706 struct inode *inode;
707 char *name;
708 int err;
709
710 inode = hostfs_iget(dir->i_sb);
711 if (IS_ERR(inode)) {
712 err = PTR_ERR(inode);
713 goto out;
714 }
715
716 err = -ENOMEM;
717 name = dentry_name(dentry);
718 if (name == NULL)
719 goto out_put;
720
721 init_special_inode(inode, mode, dev);
722 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
723 if (!err)
724 goto out_free;
725
726 err = read_name(inode, name);
727 __putname(name);
728 if (err)
729 goto out_put;
730 if (err)
731 goto out_put;
732
733 d_instantiate(dentry, inode);
734 return 0;
735
736 out_free:
737 __putname(name);
738 out_put:
739 iput(inode);
740 out:
741 return err;
742}
743
744static int hostfs_rename(struct inode *from_ino, struct dentry *from,
745 struct inode *to_ino, struct dentry *to)
746{
747 char *from_name, *to_name;
748 int err;
749
750 if ((from_name = dentry_name(from)) == NULL)
751 return -ENOMEM;
752 if ((to_name = dentry_name(to)) == NULL) {
753 __putname(from_name);
754 return -ENOMEM;
755 }
756 err = rename_file(from_name, to_name);
757 __putname(from_name);
758 __putname(to_name);
759 return err;
760}
761
762static int hostfs_permission(struct inode *ino, int desired)
763{
764 char *name;
765 int r = 0, w = 0, x = 0, err;
766
767 if (desired & MAY_NOT_BLOCK)
768 return -ECHILD;
769
770 if (desired & MAY_READ) r = 1;
771 if (desired & MAY_WRITE) w = 1;
772 if (desired & MAY_EXEC) x = 1;
773 name = inode_name(ino);
774 if (name == NULL)
775 return -ENOMEM;
776
777 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
778 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
779 err = 0;
780 else
781 err = access_file(name, r, w, x);
782 __putname(name);
783 if (!err)
784 err = generic_permission(ino, desired);
785 return err;
786}
787
788static int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
789{
790 struct inode *inode = dentry->d_inode;
791 struct hostfs_iattr attrs;
792 char *name;
793 int err;
794
795 int fd = HOSTFS_I(inode)->fd;
796
797 err = inode_change_ok(inode, attr);
798 if (err)
799 return err;
800
801 if (append)
802 attr->ia_valid &= ~ATTR_SIZE;
803
804 attrs.ia_valid = 0;
805 if (attr->ia_valid & ATTR_MODE) {
806 attrs.ia_valid |= HOSTFS_ATTR_MODE;
807 attrs.ia_mode = attr->ia_mode;
808 }
809 if (attr->ia_valid & ATTR_UID) {
810 attrs.ia_valid |= HOSTFS_ATTR_UID;
811 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid);
812 }
813 if (attr->ia_valid & ATTR_GID) {
814 attrs.ia_valid |= HOSTFS_ATTR_GID;
815 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid);
816 }
817 if (attr->ia_valid & ATTR_SIZE) {
818 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
819 attrs.ia_size = attr->ia_size;
820 }
821 if (attr->ia_valid & ATTR_ATIME) {
822 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
823 attrs.ia_atime = attr->ia_atime;
824 }
825 if (attr->ia_valid & ATTR_MTIME) {
826 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
827 attrs.ia_mtime = attr->ia_mtime;
828 }
829 if (attr->ia_valid & ATTR_CTIME) {
830 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
831 attrs.ia_ctime = attr->ia_ctime;
832 }
833 if (attr->ia_valid & ATTR_ATIME_SET) {
834 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
835 }
836 if (attr->ia_valid & ATTR_MTIME_SET) {
837 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
838 }
839 name = dentry_name(dentry);
840 if (name == NULL)
841 return -ENOMEM;
842 err = set_attr(name, &attrs, fd);
843 __putname(name);
844 if (err)
845 return err;
846
847 if ((attr->ia_valid & ATTR_SIZE) &&
848 attr->ia_size != i_size_read(inode))
849 truncate_setsize(inode, attr->ia_size);
850
851 setattr_copy(inode, attr);
852 mark_inode_dirty(inode);
853 return 0;
854}
855
856static const struct inode_operations hostfs_iops = {
857 .permission = hostfs_permission,
858 .setattr = hostfs_setattr,
859};
860
861static const struct inode_operations hostfs_dir_iops = {
862 .create = hostfs_create,
863 .lookup = hostfs_lookup,
864 .link = hostfs_link,
865 .unlink = hostfs_unlink,
866 .symlink = hostfs_symlink,
867 .mkdir = hostfs_mkdir,
868 .rmdir = hostfs_rmdir,
869 .mknod = hostfs_mknod,
870 .rename = hostfs_rename,
871 .permission = hostfs_permission,
872 .setattr = hostfs_setattr,
873};
874
875static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd)
876{
877 char *link = __getname();
878 if (link) {
879 char *path = dentry_name(dentry);
880 int err = -ENOMEM;
881 if (path) {
882 err = hostfs_do_readlink(path, link, PATH_MAX);
883 if (err == PATH_MAX)
884 err = -E2BIG;
885 __putname(path);
886 }
887 if (err < 0) {
888 __putname(link);
889 link = ERR_PTR(err);
890 }
891 } else {
892 link = ERR_PTR(-ENOMEM);
893 }
894
895 nd_set_link(nd, link);
896 return NULL;
897}
898
899static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
900{
901 char *s = nd_get_link(nd);
902 if (!IS_ERR(s))
903 __putname(s);
904}
905
906static const struct inode_operations hostfs_link_iops = {
907 .readlink = generic_readlink,
908 .follow_link = hostfs_follow_link,
909 .put_link = hostfs_put_link,
910};
911
912static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
913{
914 struct inode *root_inode;
915 char *host_root_path, *req_root = d;
916 int err;
917
918 sb->s_blocksize = 1024;
919 sb->s_blocksize_bits = 10;
920 sb->s_magic = HOSTFS_SUPER_MAGIC;
921 sb->s_op = &hostfs_sbops;
922 sb->s_d_op = &simple_dentry_operations;
923 sb->s_maxbytes = MAX_LFS_FILESIZE;
924
925 /* NULL is printed as <NULL> by sprintf: avoid that. */
926 if (req_root == NULL)
927 req_root = "";
928
929 err = -ENOMEM;
930 sb->s_fs_info = host_root_path =
931 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL);
932 if (host_root_path == NULL)
933 goto out;
934
935 sprintf(host_root_path, "%s/%s", root_ino, req_root);
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 else
950 err = read_name(root_inode, name);
951 kfree(name);
952 if (err)
953 goto out_put;
954 }
955
956 err = -ENOMEM;
957 sb->s_root = d_make_root(root_inode);
958 if (sb->s_root == NULL)
959 goto out;
960
961 return 0;
962
963out_put:
964 iput(root_inode);
965out:
966 return err;
967}
968
969static struct dentry *hostfs_read_sb(struct file_system_type *type,
970 int flags, const char *dev_name,
971 void *data)
972{
973 return mount_nodev(type, flags, data, hostfs_fill_sb_common);
974}
975
976static void hostfs_kill_sb(struct super_block *s)
977{
978 kill_anon_super(s);
979 kfree(s->s_fs_info);
980}
981
982static struct file_system_type hostfs_type = {
983 .owner = THIS_MODULE,
984 .name = "hostfs",
985 .mount = hostfs_read_sb,
986 .kill_sb = hostfs_kill_sb,
987 .fs_flags = 0,
988};
989MODULE_ALIAS_FS("hostfs");
990
991static int __init init_hostfs(void)
992{
993 return register_filesystem(&hostfs_type);
994}
995
996static void __exit exit_hostfs(void)
997{
998 unregister_filesystem(&hostfs_type);
999}
1000
1001module_init(init_hostfs)
1002module_exit(exit_hostfs)
1003MODULE_LICENSE("GPL");