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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/namei.h>
20#include "hostfs.h"
21#include <init.h>
22#include <kern.h>
23
24struct hostfs_inode_info {
25 int fd;
26 fmode_t mode;
27 struct inode vfs_inode;
28 struct mutex open_mutex;
29 dev_t dev;
30};
31
32static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
33{
34 return list_entry(inode, struct hostfs_inode_info, vfs_inode);
35}
36
37#define FILE_HOSTFS_I(file) HOSTFS_I(file_inode(file))
38
39static struct kmem_cache *hostfs_inode_cache;
40
41/* Changed in hostfs_args before the kernel starts running */
42static char *root_ino = "";
43static int append = 0;
44
45static const struct inode_operations hostfs_iops;
46static const struct inode_operations hostfs_dir_iops;
47static const struct inode_operations hostfs_link_iops;
48
49#ifndef MODULE
50static int __init hostfs_args(char *options, int *add)
51{
52 char *ptr;
53
54 ptr = strchr(options, ',');
55 if (ptr != NULL)
56 *ptr++ = '\0';
57 if (*options != '\0')
58 root_ino = options;
59
60 options = ptr;
61 while (options) {
62 ptr = strchr(options, ',');
63 if (ptr != NULL)
64 *ptr++ = '\0';
65 if (*options != '\0') {
66 if (!strcmp(options, "append"))
67 append = 1;
68 else printf("hostfs_args - unsupported option - %s\n",
69 options);
70 }
71 options = ptr;
72 }
73 return 0;
74}
75
76__uml_setup("hostfs=", hostfs_args,
77"hostfs=<root dir>,<flags>,...\n"
78" This is used to set hostfs parameters. The root directory argument\n"
79" is used to confine all hostfs mounts to within the specified directory\n"
80" tree on the host. If this isn't specified, then a user inside UML can\n"
81" mount anything on the host that's accessible to the user that's running\n"
82" it.\n"
83" The only flag currently supported is 'append', which specifies that all\n"
84" files opened by hostfs will be opened in append mode.\n\n"
85);
86#endif
87
88static char *__dentry_name(struct dentry *dentry, char *name)
89{
90 char *p = dentry_path_raw(dentry, name, PATH_MAX);
91 char *root;
92 size_t len;
93
94 root = dentry->d_sb->s_fs_info;
95 len = strlen(root);
96 if (IS_ERR(p)) {
97 __putname(name);
98 return NULL;
99 }
100
101 /*
102 * This function relies on the fact that dentry_path_raw() will place
103 * the path name at the end of the provided buffer.
104 */
105 BUG_ON(p + strlen(p) + 1 != name + PATH_MAX);
106
107 strscpy(name, root, PATH_MAX);
108 if (len > p - name) {
109 __putname(name);
110 return NULL;
111 }
112
113 if (p > name + len)
114 strcpy(name + len, p);
115
116 return name;
117}
118
119static char *dentry_name(struct dentry *dentry)
120{
121 char *name = __getname();
122 if (!name)
123 return NULL;
124
125 return __dentry_name(dentry, name);
126}
127
128static char *inode_name(struct inode *ino)
129{
130 struct dentry *dentry;
131 char *name;
132
133 dentry = d_find_alias(ino);
134 if (!dentry)
135 return NULL;
136
137 name = dentry_name(dentry);
138
139 dput(dentry);
140
141 return name;
142}
143
144static char *follow_link(char *link)
145{
146 char *name, *resolved, *end;
147 int n;
148
149 name = kmalloc(PATH_MAX, GFP_KERNEL);
150 if (!name) {
151 n = -ENOMEM;
152 goto out_free;
153 }
154
155 n = hostfs_do_readlink(link, name, PATH_MAX);
156 if (n < 0)
157 goto out_free;
158 else if (n == PATH_MAX) {
159 n = -E2BIG;
160 goto out_free;
161 }
162
163 if (*name == '/')
164 return name;
165
166 end = strrchr(link, '/');
167 if (end == NULL)
168 return name;
169
170 *(end + 1) = '\0';
171
172 resolved = kasprintf(GFP_KERNEL, "%s%s", link, name);
173 if (resolved == NULL) {
174 n = -ENOMEM;
175 goto out_free;
176 }
177
178 kfree(name);
179 return resolved;
180
181 out_free:
182 kfree(name);
183 return ERR_PTR(n);
184}
185
186static int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
187{
188 /*
189 * do_statfs uses struct statfs64 internally, but the linux kernel
190 * struct statfs still has 32-bit versions for most of these fields,
191 * so we convert them here
192 */
193 int err;
194 long long f_blocks;
195 long long f_bfree;
196 long long f_bavail;
197 long long f_files;
198 long long f_ffree;
199
200 err = do_statfs(dentry->d_sb->s_fs_info,
201 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
202 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
203 &sf->f_namelen);
204 if (err)
205 return err;
206 sf->f_blocks = f_blocks;
207 sf->f_bfree = f_bfree;
208 sf->f_bavail = f_bavail;
209 sf->f_files = f_files;
210 sf->f_ffree = f_ffree;
211 sf->f_type = HOSTFS_SUPER_MAGIC;
212 return 0;
213}
214
215static struct inode *hostfs_alloc_inode(struct super_block *sb)
216{
217 struct hostfs_inode_info *hi;
218
219 hi = alloc_inode_sb(sb, hostfs_inode_cache, GFP_KERNEL_ACCOUNT);
220 if (hi == NULL)
221 return NULL;
222 hi->fd = -1;
223 hi->mode = 0;
224 hi->dev = 0;
225 inode_init_once(&hi->vfs_inode);
226 mutex_init(&hi->open_mutex);
227 return &hi->vfs_inode;
228}
229
230static void hostfs_evict_inode(struct inode *inode)
231{
232 truncate_inode_pages_final(&inode->i_data);
233 clear_inode(inode);
234 if (HOSTFS_I(inode)->fd != -1) {
235 close_file(&HOSTFS_I(inode)->fd);
236 HOSTFS_I(inode)->fd = -1;
237 HOSTFS_I(inode)->dev = 0;
238 }
239}
240
241static void hostfs_free_inode(struct inode *inode)
242{
243 kmem_cache_free(hostfs_inode_cache, HOSTFS_I(inode));
244}
245
246static int hostfs_show_options(struct seq_file *seq, struct dentry *root)
247{
248 const char *root_path = root->d_sb->s_fs_info;
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 struct page *page = &folio->page;
436 char *buffer;
437 loff_t start = page_offset(page);
438 int bytes_read, ret = 0;
439
440 buffer = kmap_local_page(page);
441 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
442 PAGE_SIZE);
443 if (bytes_read < 0) {
444 ClearPageUptodate(page);
445 SetPageError(page);
446 ret = bytes_read;
447 goto out;
448 }
449
450 memset(buffer + bytes_read, 0, PAGE_SIZE - bytes_read);
451
452 ClearPageError(page);
453 SetPageUptodate(page);
454
455 out:
456 flush_dcache_page(page);
457 kunmap_local(buffer);
458 unlock_page(page);
459
460 return ret;
461}
462
463static int hostfs_write_begin(struct file *file, struct address_space *mapping,
464 loff_t pos, unsigned len,
465 struct page **pagep, void **fsdata)
466{
467 pgoff_t index = pos >> PAGE_SHIFT;
468
469 *pagep = grab_cache_page_write_begin(mapping, index);
470 if (!*pagep)
471 return -ENOMEM;
472 return 0;
473}
474
475static 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_local_page(page);
485 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
486 kunmap_local(buffer);
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
503static const struct address_space_operations hostfs_aops = {
504 .writepage = hostfs_writepage,
505 .read_folio = hostfs_read_folio,
506 .dirty_folio = filemap_dirty_folio,
507 .write_begin = hostfs_write_begin,
508 .write_end = hostfs_write_end,
509};
510
511static int hostfs_inode_update(struct inode *ino, const struct hostfs_stat *st)
512{
513 set_nlink(ino, st->nlink);
514 i_uid_write(ino, st->uid);
515 i_gid_write(ino, st->gid);
516 inode_set_atime_to_ts(ino, (struct timespec64){
517 st->atime.tv_sec,
518 st->atime.tv_nsec,
519 });
520 inode_set_mtime_to_ts(ino, (struct timespec64){
521 st->mtime.tv_sec,
522 st->mtime.tv_nsec,
523 });
524 inode_set_ctime(ino, st->ctime.tv_sec, st->ctime.tv_nsec);
525 ino->i_size = st->size;
526 ino->i_blocks = st->blocks;
527 return 0;
528}
529
530static int hostfs_inode_set(struct inode *ino, void *data)
531{
532 struct hostfs_stat *st = data;
533 dev_t rdev;
534
535 /* Reencode maj and min with the kernel encoding.*/
536 rdev = MKDEV(st->maj, st->min);
537
538 switch (st->mode & S_IFMT) {
539 case S_IFLNK:
540 ino->i_op = &hostfs_link_iops;
541 break;
542 case S_IFDIR:
543 ino->i_op = &hostfs_dir_iops;
544 ino->i_fop = &hostfs_dir_fops;
545 break;
546 case S_IFCHR:
547 case S_IFBLK:
548 case S_IFIFO:
549 case S_IFSOCK:
550 init_special_inode(ino, st->mode & S_IFMT, rdev);
551 ino->i_op = &hostfs_iops;
552 break;
553 case S_IFREG:
554 ino->i_op = &hostfs_iops;
555 ino->i_fop = &hostfs_file_fops;
556 ino->i_mapping->a_ops = &hostfs_aops;
557 break;
558 default:
559 return -EIO;
560 }
561
562 HOSTFS_I(ino)->dev = st->dev;
563 ino->i_ino = st->ino;
564 ino->i_mode = st->mode;
565 return hostfs_inode_update(ino, st);
566}
567
568static int hostfs_inode_test(struct inode *inode, void *data)
569{
570 const struct hostfs_stat *st = data;
571
572 return inode->i_ino == st->ino && HOSTFS_I(inode)->dev == st->dev;
573}
574
575static struct inode *hostfs_iget(struct super_block *sb, char *name)
576{
577 struct inode *inode;
578 struct hostfs_stat st;
579 int err = stat_file(name, &st, -1);
580
581 if (err)
582 return ERR_PTR(err);
583
584 inode = iget5_locked(sb, st.ino, hostfs_inode_test, hostfs_inode_set,
585 &st);
586 if (!inode)
587 return ERR_PTR(-ENOMEM);
588
589 if (inode->i_state & I_NEW) {
590 unlock_new_inode(inode);
591 } else {
592 spin_lock(&inode->i_lock);
593 hostfs_inode_update(inode, &st);
594 spin_unlock(&inode->i_lock);
595 }
596
597 return inode;
598}
599
600static int hostfs_create(struct mnt_idmap *idmap, struct inode *dir,
601 struct dentry *dentry, umode_t mode, bool excl)
602{
603 struct inode *inode;
604 char *name;
605 int fd;
606
607 name = dentry_name(dentry);
608 if (name == NULL)
609 return -ENOMEM;
610
611 fd = file_create(name, mode & 0777);
612 if (fd < 0) {
613 __putname(name);
614 return fd;
615 }
616
617 inode = hostfs_iget(dir->i_sb, name);
618 __putname(name);
619 if (IS_ERR(inode))
620 return PTR_ERR(inode);
621
622 HOSTFS_I(inode)->fd = fd;
623 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
624 d_instantiate(dentry, inode);
625 return 0;
626}
627
628static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
629 unsigned int flags)
630{
631 struct inode *inode = NULL;
632 char *name;
633
634 name = dentry_name(dentry);
635 if (name == NULL)
636 return ERR_PTR(-ENOMEM);
637
638 inode = hostfs_iget(ino->i_sb, name);
639 __putname(name);
640 if (inode == ERR_PTR(-ENOENT))
641 inode = NULL;
642
643 return d_splice_alias(inode, dentry);
644}
645
646static int hostfs_link(struct dentry *to, struct inode *ino,
647 struct dentry *from)
648{
649 char *from_name, *to_name;
650 int err;
651
652 if ((from_name = dentry_name(from)) == NULL)
653 return -ENOMEM;
654 to_name = dentry_name(to);
655 if (to_name == NULL) {
656 __putname(from_name);
657 return -ENOMEM;
658 }
659 err = link_file(to_name, from_name);
660 __putname(from_name);
661 __putname(to_name);
662 return err;
663}
664
665static int hostfs_unlink(struct inode *ino, struct dentry *dentry)
666{
667 char *file;
668 int err;
669
670 if (append)
671 return -EPERM;
672
673 if ((file = dentry_name(dentry)) == NULL)
674 return -ENOMEM;
675
676 err = unlink_file(file);
677 __putname(file);
678 return err;
679}
680
681static int hostfs_symlink(struct mnt_idmap *idmap, struct inode *ino,
682 struct dentry *dentry, const char *to)
683{
684 char *file;
685 int err;
686
687 if ((file = dentry_name(dentry)) == NULL)
688 return -ENOMEM;
689 err = make_symlink(file, to);
690 __putname(file);
691 return err;
692}
693
694static int hostfs_mkdir(struct mnt_idmap *idmap, struct inode *ino,
695 struct dentry *dentry, umode_t mode)
696{
697 char *file;
698 int err;
699
700 if ((file = dentry_name(dentry)) == NULL)
701 return -ENOMEM;
702 err = do_mkdir(file, mode);
703 __putname(file);
704 return err;
705}
706
707static int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
708{
709 char *file;
710 int err;
711
712 if ((file = dentry_name(dentry)) == NULL)
713 return -ENOMEM;
714 err = hostfs_do_rmdir(file);
715 __putname(file);
716 return err;
717}
718
719static int hostfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
720 struct dentry *dentry, umode_t mode, dev_t dev)
721{
722 struct inode *inode;
723 char *name;
724 int err;
725
726 name = dentry_name(dentry);
727 if (name == NULL)
728 return -ENOMEM;
729
730 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
731 if (err) {
732 __putname(name);
733 return err;
734 }
735
736 inode = hostfs_iget(dir->i_sb, name);
737 __putname(name);
738 if (IS_ERR(inode))
739 return PTR_ERR(inode);
740
741 d_instantiate(dentry, inode);
742 return 0;
743}
744
745static int hostfs_rename2(struct mnt_idmap *idmap,
746 struct inode *old_dir, struct dentry *old_dentry,
747 struct inode *new_dir, struct dentry *new_dentry,
748 unsigned int flags)
749{
750 char *old_name, *new_name;
751 int err;
752
753 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
754 return -EINVAL;
755
756 old_name = dentry_name(old_dentry);
757 if (old_name == NULL)
758 return -ENOMEM;
759 new_name = dentry_name(new_dentry);
760 if (new_name == NULL) {
761 __putname(old_name);
762 return -ENOMEM;
763 }
764 if (!flags)
765 err = rename_file(old_name, new_name);
766 else
767 err = rename2_file(old_name, new_name, flags);
768
769 __putname(old_name);
770 __putname(new_name);
771 return err;
772}
773
774static int hostfs_permission(struct mnt_idmap *idmap,
775 struct inode *ino, int desired)
776{
777 char *name;
778 int r = 0, w = 0, x = 0, err;
779
780 if (desired & MAY_NOT_BLOCK)
781 return -ECHILD;
782
783 if (desired & MAY_READ) r = 1;
784 if (desired & MAY_WRITE) w = 1;
785 if (desired & MAY_EXEC) x = 1;
786 name = inode_name(ino);
787 if (name == NULL)
788 return -ENOMEM;
789
790 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
791 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
792 err = 0;
793 else
794 err = access_file(name, r, w, x);
795 __putname(name);
796 if (!err)
797 err = generic_permission(&nop_mnt_idmap, ino, desired);
798 return err;
799}
800
801static int hostfs_setattr(struct mnt_idmap *idmap,
802 struct dentry *dentry, struct iattr *attr)
803{
804 struct inode *inode = d_inode(dentry);
805 struct hostfs_iattr attrs;
806 char *name;
807 int err;
808
809 int fd = HOSTFS_I(inode)->fd;
810
811 err = setattr_prepare(&nop_mnt_idmap, dentry, attr);
812 if (err)
813 return err;
814
815 if (append)
816 attr->ia_valid &= ~ATTR_SIZE;
817
818 attrs.ia_valid = 0;
819 if (attr->ia_valid & ATTR_MODE) {
820 attrs.ia_valid |= HOSTFS_ATTR_MODE;
821 attrs.ia_mode = attr->ia_mode;
822 }
823 if (attr->ia_valid & ATTR_UID) {
824 attrs.ia_valid |= HOSTFS_ATTR_UID;
825 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid);
826 }
827 if (attr->ia_valid & ATTR_GID) {
828 attrs.ia_valid |= HOSTFS_ATTR_GID;
829 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid);
830 }
831 if (attr->ia_valid & ATTR_SIZE) {
832 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
833 attrs.ia_size = attr->ia_size;
834 }
835 if (attr->ia_valid & ATTR_ATIME) {
836 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
837 attrs.ia_atime = (struct hostfs_timespec)
838 { attr->ia_atime.tv_sec, attr->ia_atime.tv_nsec };
839 }
840 if (attr->ia_valid & ATTR_MTIME) {
841 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
842 attrs.ia_mtime = (struct hostfs_timespec)
843 { attr->ia_mtime.tv_sec, attr->ia_mtime.tv_nsec };
844 }
845 if (attr->ia_valid & ATTR_CTIME) {
846 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
847 attrs.ia_ctime = (struct hostfs_timespec)
848 { attr->ia_ctime.tv_sec, attr->ia_ctime.tv_nsec };
849 }
850 if (attr->ia_valid & ATTR_ATIME_SET) {
851 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
852 }
853 if (attr->ia_valid & ATTR_MTIME_SET) {
854 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
855 }
856 name = dentry_name(dentry);
857 if (name == NULL)
858 return -ENOMEM;
859 err = set_attr(name, &attrs, fd);
860 __putname(name);
861 if (err)
862 return err;
863
864 if ((attr->ia_valid & ATTR_SIZE) &&
865 attr->ia_size != i_size_read(inode))
866 truncate_setsize(inode, attr->ia_size);
867
868 setattr_copy(&nop_mnt_idmap, inode, attr);
869 mark_inode_dirty(inode);
870 return 0;
871}
872
873static const struct inode_operations hostfs_iops = {
874 .permission = hostfs_permission,
875 .setattr = hostfs_setattr,
876};
877
878static const struct inode_operations hostfs_dir_iops = {
879 .create = hostfs_create,
880 .lookup = hostfs_lookup,
881 .link = hostfs_link,
882 .unlink = hostfs_unlink,
883 .symlink = hostfs_symlink,
884 .mkdir = hostfs_mkdir,
885 .rmdir = hostfs_rmdir,
886 .mknod = hostfs_mknod,
887 .rename = hostfs_rename2,
888 .permission = hostfs_permission,
889 .setattr = hostfs_setattr,
890};
891
892static const char *hostfs_get_link(struct dentry *dentry,
893 struct inode *inode,
894 struct delayed_call *done)
895{
896 char *link;
897 if (!dentry)
898 return ERR_PTR(-ECHILD);
899 link = kmalloc(PATH_MAX, GFP_KERNEL);
900 if (link) {
901 char *path = dentry_name(dentry);
902 int err = -ENOMEM;
903 if (path) {
904 err = hostfs_do_readlink(path, link, PATH_MAX);
905 if (err == PATH_MAX)
906 err = -E2BIG;
907 __putname(path);
908 }
909 if (err < 0) {
910 kfree(link);
911 return ERR_PTR(err);
912 }
913 } else {
914 return ERR_PTR(-ENOMEM);
915 }
916
917 set_delayed_call(done, kfree_link, link);
918 return link;
919}
920
921static const struct inode_operations hostfs_link_iops = {
922 .get_link = hostfs_get_link,
923};
924
925static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
926{
927 struct inode *root_inode;
928 char *host_root_path, *req_root = d;
929 int err;
930
931 sb->s_blocksize = 1024;
932 sb->s_blocksize_bits = 10;
933 sb->s_magic = HOSTFS_SUPER_MAGIC;
934 sb->s_op = &hostfs_sbops;
935 sb->s_d_op = &simple_dentry_operations;
936 sb->s_maxbytes = MAX_LFS_FILESIZE;
937 err = super_setup_bdi(sb);
938 if (err)
939 return err;
940
941 /* NULL is printed as '(null)' by printf(): avoid that. */
942 if (req_root == NULL)
943 req_root = "";
944
945 sb->s_fs_info = host_root_path =
946 kasprintf(GFP_KERNEL, "%s/%s", root_ino, req_root);
947 if (host_root_path == NULL)
948 return -ENOMEM;
949
950 root_inode = hostfs_iget(sb, host_root_path);
951 if (IS_ERR(root_inode))
952 return PTR_ERR(root_inode);
953
954 if (S_ISLNK(root_inode->i_mode)) {
955 char *name;
956
957 iput(root_inode);
958 name = follow_link(host_root_path);
959 if (IS_ERR(name))
960 return PTR_ERR(name);
961
962 root_inode = hostfs_iget(sb, name);
963 kfree(name);
964 if (IS_ERR(root_inode))
965 return PTR_ERR(root_inode);
966 }
967
968 sb->s_root = d_make_root(root_inode);
969 if (sb->s_root == NULL)
970 return -ENOMEM;
971
972 return 0;
973}
974
975static struct dentry *hostfs_read_sb(struct file_system_type *type,
976 int flags, const char *dev_name,
977 void *data)
978{
979 return mount_nodev(type, flags, data, hostfs_fill_sb_common);
980}
981
982static void hostfs_kill_sb(struct super_block *s)
983{
984 kill_anon_super(s);
985 kfree(s->s_fs_info);
986}
987
988static struct file_system_type hostfs_type = {
989 .owner = THIS_MODULE,
990 .name = "hostfs",
991 .mount = hostfs_read_sb,
992 .kill_sb = hostfs_kill_sb,
993 .fs_flags = 0,
994};
995MODULE_ALIAS_FS("hostfs");
996
997static int __init init_hostfs(void)
998{
999 hostfs_inode_cache = KMEM_CACHE(hostfs_inode_info, 0);
1000 if (!hostfs_inode_cache)
1001 return -ENOMEM;
1002 return register_filesystem(&hostfs_type);
1003}
1004
1005static void __exit exit_hostfs(void)
1006{
1007 unregister_filesystem(&hostfs_type);
1008 kmem_cache_destroy(hostfs_inode_cache);
1009}
1010
1011module_init(init_hostfs)
1012module_exit(exit_hostfs)
1013MODULE_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 struct mutex open_mutex;
28};
29
30static 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/* Changed in hostfs_args before the kernel starts running */
38static char *root_ino = "";
39static int append = 0;
40
41static const struct inode_operations hostfs_iops;
42static const struct inode_operations hostfs_dir_iops;
43static const struct inode_operations hostfs_link_iops;
44
45#ifndef MODULE
46static int __init hostfs_args(char *options, int *add)
47{
48 char *ptr;
49
50 ptr = strchr(options, ',');
51 if (ptr != NULL)
52 *ptr++ = '\0';
53 if (*options != '\0')
54 root_ino = options;
55
56 options = ptr;
57 while (options) {
58 ptr = strchr(options, ',');
59 if (ptr != NULL)
60 *ptr++ = '\0';
61 if (*options != '\0') {
62 if (!strcmp(options, "append"))
63 append = 1;
64 else printf("hostfs_args - unsupported option - %s\n",
65 options);
66 }
67 options = ptr;
68 }
69 return 0;
70}
71
72__uml_setup("hostfs=", hostfs_args,
73"hostfs=<root dir>,<flags>,...\n"
74" This is used to set hostfs parameters. The root directory argument\n"
75" is used to confine all hostfs mounts to within the specified directory\n"
76" tree on the host. If this isn't specified, then a user inside UML can\n"
77" mount anything on the host that's accessible to the user that's running\n"
78" it.\n"
79" The only flag currently supported is 'append', which specifies that all\n"
80" files opened by hostfs will be opened in append mode.\n\n"
81);
82#endif
83
84static char *__dentry_name(struct dentry *dentry, char *name)
85{
86 char *p = dentry_path_raw(dentry, name, PATH_MAX);
87 char *root;
88 size_t len;
89
90 root = dentry->d_sb->s_fs_info;
91 len = strlen(root);
92 if (IS_ERR(p)) {
93 __putname(name);
94 return NULL;
95 }
96
97 /*
98 * This function relies on the fact that dentry_path_raw() will place
99 * the path name at the end of the provided buffer.
100 */
101 BUG_ON(p + strlen(p) + 1 != name + PATH_MAX);
102
103 strlcpy(name, root, PATH_MAX);
104 if (len > p - name) {
105 __putname(name);
106 return NULL;
107 }
108
109 if (p > name + len)
110 strcpy(name + len, p);
111
112 return name;
113}
114
115static char *dentry_name(struct dentry *dentry)
116{
117 char *name = __getname();
118 if (!name)
119 return NULL;
120
121 return __dentry_name(dentry, name);
122}
123
124static char *inode_name(struct inode *ino)
125{
126 struct dentry *dentry;
127 char *name;
128
129 dentry = d_find_alias(ino);
130 if (!dentry)
131 return NULL;
132
133 name = dentry_name(dentry);
134
135 dput(dentry);
136
137 return name;
138}
139
140static char *follow_link(char *link)
141{
142 int len, n;
143 char *name, *resolved, *end;
144
145 name = __getname();
146 if (!name) {
147 n = -ENOMEM;
148 goto out_free;
149 }
150
151 n = hostfs_do_readlink(link, name, PATH_MAX);
152 if (n < 0)
153 goto out_free;
154 else if (n == PATH_MAX) {
155 n = -E2BIG;
156 goto out_free;
157 }
158
159 if (*name == '/')
160 return name;
161
162 end = strrchr(link, '/');
163 if (end == NULL)
164 return name;
165
166 *(end + 1) = '\0';
167 len = strlen(link) + strlen(name) + 1;
168
169 resolved = kmalloc(len, GFP_KERNEL);
170 if (resolved == NULL) {
171 n = -ENOMEM;
172 goto out_free;
173 }
174
175 sprintf(resolved, "%s%s", link, name);
176 __putname(name);
177 kfree(link);
178 return resolved;
179
180 out_free:
181 __putname(name);
182 return ERR_PTR(n);
183}
184
185static struct inode *hostfs_iget(struct super_block *sb)
186{
187 struct inode *inode = new_inode(sb);
188 if (!inode)
189 return ERR_PTR(-ENOMEM);
190 return inode;
191}
192
193static int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
194{
195 /*
196 * do_statfs uses struct statfs64 internally, but the linux kernel
197 * struct statfs still has 32-bit versions for most of these fields,
198 * so we convert them here
199 */
200 int err;
201 long long f_blocks;
202 long long f_bfree;
203 long long f_bavail;
204 long long f_files;
205 long long f_ffree;
206
207 err = do_statfs(dentry->d_sb->s_fs_info,
208 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
209 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
210 &sf->f_namelen);
211 if (err)
212 return err;
213 sf->f_blocks = f_blocks;
214 sf->f_bfree = f_bfree;
215 sf->f_bavail = f_bavail;
216 sf->f_files = f_files;
217 sf->f_ffree = f_ffree;
218 sf->f_type = HOSTFS_SUPER_MAGIC;
219 return 0;
220}
221
222static struct inode *hostfs_alloc_inode(struct super_block *sb)
223{
224 struct hostfs_inode_info *hi;
225
226 hi = kmalloc(sizeof(*hi), GFP_KERNEL_ACCOUNT);
227 if (hi == NULL)
228 return NULL;
229 hi->fd = -1;
230 hi->mode = 0;
231 inode_init_once(&hi->vfs_inode);
232 mutex_init(&hi->open_mutex);
233 return &hi->vfs_inode;
234}
235
236static void hostfs_evict_inode(struct inode *inode)
237{
238 truncate_inode_pages_final(&inode->i_data);
239 clear_inode(inode);
240 if (HOSTFS_I(inode)->fd != -1) {
241 close_file(&HOSTFS_I(inode)->fd);
242 HOSTFS_I(inode)->fd = -1;
243 }
244}
245
246static void hostfs_i_callback(struct rcu_head *head)
247{
248 struct inode *inode = container_of(head, struct inode, i_rcu);
249 kfree(HOSTFS_I(inode));
250}
251
252static void hostfs_destroy_inode(struct inode *inode)
253{
254 call_rcu(&inode->i_rcu, hostfs_i_callback);
255}
256
257static int hostfs_show_options(struct seq_file *seq, struct dentry *root)
258{
259 const char *root_path = root->d_sb->s_fs_info;
260 size_t offset = strlen(root_ino) + 1;
261
262 if (strlen(root_path) > offset)
263 seq_show_option(seq, root_path + offset, NULL);
264
265 if (append)
266 seq_puts(seq, ",append");
267
268 return 0;
269}
270
271static const struct super_operations hostfs_sbops = {
272 .alloc_inode = hostfs_alloc_inode,
273 .destroy_inode = hostfs_destroy_inode,
274 .evict_inode = hostfs_evict_inode,
275 .statfs = hostfs_statfs,
276 .show_options = hostfs_show_options,
277};
278
279static int hostfs_readdir(struct file *file, struct dir_context *ctx)
280{
281 void *dir;
282 char *name;
283 unsigned long long next, ino;
284 int error, len;
285 unsigned int type;
286
287 name = dentry_name(file->f_path.dentry);
288 if (name == NULL)
289 return -ENOMEM;
290 dir = open_dir(name, &error);
291 __putname(name);
292 if (dir == NULL)
293 return -error;
294 next = ctx->pos;
295 seek_dir(dir, next);
296 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) {
297 if (!dir_emit(ctx, name, len, ino, type))
298 break;
299 ctx->pos = next;
300 }
301 close_dir(dir);
302 return 0;
303}
304
305static int hostfs_open(struct inode *ino, struct file *file)
306{
307 char *name;
308 fmode_t mode;
309 int err;
310 int r, w, fd;
311
312 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
313 if ((mode & HOSTFS_I(ino)->mode) == mode)
314 return 0;
315
316 mode |= HOSTFS_I(ino)->mode;
317
318retry:
319 r = w = 0;
320
321 if (mode & FMODE_READ)
322 r = 1;
323 if (mode & FMODE_WRITE)
324 r = w = 1;
325
326 name = dentry_name(file->f_path.dentry);
327 if (name == NULL)
328 return -ENOMEM;
329
330 fd = open_file(name, r, w, append);
331 __putname(name);
332 if (fd < 0)
333 return fd;
334
335 mutex_lock(&HOSTFS_I(ino)->open_mutex);
336 /* somebody else had handled it first? */
337 if ((mode & HOSTFS_I(ino)->mode) == mode) {
338 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
339 close_file(&fd);
340 return 0;
341 }
342 if ((mode | HOSTFS_I(ino)->mode) != mode) {
343 mode |= HOSTFS_I(ino)->mode;
344 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
345 close_file(&fd);
346 goto retry;
347 }
348 if (HOSTFS_I(ino)->fd == -1) {
349 HOSTFS_I(ino)->fd = fd;
350 } else {
351 err = replace_file(fd, HOSTFS_I(ino)->fd);
352 close_file(&fd);
353 if (err < 0) {
354 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
355 return err;
356 }
357 }
358 HOSTFS_I(ino)->mode = mode;
359 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
360
361 return 0;
362}
363
364static int hostfs_file_release(struct inode *inode, struct file *file)
365{
366 filemap_write_and_wait(inode->i_mapping);
367
368 return 0;
369}
370
371static int hostfs_fsync(struct file *file, loff_t start, loff_t end,
372 int datasync)
373{
374 struct inode *inode = file->f_mapping->host;
375 int ret;
376
377 ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
378 if (ret)
379 return ret;
380
381 inode_lock(inode);
382 ret = fsync_file(HOSTFS_I(inode)->fd, datasync);
383 inode_unlock(inode);
384
385 return ret;
386}
387
388static const struct file_operations hostfs_file_fops = {
389 .llseek = generic_file_llseek,
390 .splice_read = generic_file_splice_read,
391 .read_iter = generic_file_read_iter,
392 .write_iter = generic_file_write_iter,
393 .mmap = generic_file_mmap,
394 .open = hostfs_open,
395 .release = hostfs_file_release,
396 .fsync = hostfs_fsync,
397};
398
399static const struct file_operations hostfs_dir_fops = {
400 .llseek = generic_file_llseek,
401 .iterate = hostfs_readdir,
402 .read = generic_read_dir,
403 .open = hostfs_open,
404 .fsync = hostfs_fsync,
405};
406
407static int hostfs_writepage(struct page *page, struct writeback_control *wbc)
408{
409 struct address_space *mapping = page->mapping;
410 struct inode *inode = mapping->host;
411 char *buffer;
412 loff_t base = page_offset(page);
413 int count = PAGE_SIZE;
414 int end_index = inode->i_size >> PAGE_SHIFT;
415 int err;
416
417 if (page->index >= end_index)
418 count = inode->i_size & (PAGE_SIZE-1);
419
420 buffer = kmap(page);
421
422 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
423 if (err != count) {
424 ClearPageUptodate(page);
425 goto out;
426 }
427
428 if (base > inode->i_size)
429 inode->i_size = base;
430
431 if (PageError(page))
432 ClearPageError(page);
433 err = 0;
434
435 out:
436 kunmap(page);
437
438 unlock_page(page);
439 return err;
440}
441
442static int hostfs_readpage(struct file *file, struct page *page)
443{
444 char *buffer;
445 loff_t start = page_offset(page);
446 int bytes_read, ret = 0;
447
448 buffer = kmap(page);
449 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
450 PAGE_SIZE);
451 if (bytes_read < 0) {
452 ClearPageUptodate(page);
453 SetPageError(page);
454 ret = bytes_read;
455 goto out;
456 }
457
458 memset(buffer + bytes_read, 0, PAGE_SIZE - bytes_read);
459
460 ClearPageError(page);
461 SetPageUptodate(page);
462
463 out:
464 flush_dcache_page(page);
465 kunmap(page);
466 unlock_page(page);
467 return ret;
468}
469
470static int hostfs_write_begin(struct file *file, struct address_space *mapping,
471 loff_t pos, unsigned len, unsigned flags,
472 struct page **pagep, void **fsdata)
473{
474 pgoff_t index = pos >> PAGE_SHIFT;
475
476 *pagep = grab_cache_page_write_begin(mapping, index, flags);
477 if (!*pagep)
478 return -ENOMEM;
479 return 0;
480}
481
482static int hostfs_write_end(struct file *file, struct address_space *mapping,
483 loff_t pos, unsigned len, unsigned copied,
484 struct page *page, void *fsdata)
485{
486 struct inode *inode = mapping->host;
487 void *buffer;
488 unsigned from = pos & (PAGE_SIZE - 1);
489 int err;
490
491 buffer = kmap(page);
492 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
493 kunmap(page);
494
495 if (!PageUptodate(page) && err == PAGE_SIZE)
496 SetPageUptodate(page);
497
498 /*
499 * If err > 0, write_file has added err to pos, so we are comparing
500 * i_size against the last byte written.
501 */
502 if (err > 0 && (pos > inode->i_size))
503 inode->i_size = pos;
504 unlock_page(page);
505 put_page(page);
506
507 return err;
508}
509
510static const struct address_space_operations hostfs_aops = {
511 .writepage = hostfs_writepage,
512 .readpage = hostfs_readpage,
513 .set_page_dirty = __set_page_dirty_nobuffers,
514 .write_begin = hostfs_write_begin,
515 .write_end = hostfs_write_end,
516};
517
518static int read_name(struct inode *ino, char *name)
519{
520 dev_t rdev;
521 struct hostfs_stat st;
522 int err = stat_file(name, &st, -1);
523 if (err)
524 return err;
525
526 /* Reencode maj and min with the kernel encoding.*/
527 rdev = MKDEV(st.maj, st.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 ino->i_ino = st.ino;
554 ino->i_mode = st.mode;
555 set_nlink(ino, st.nlink);
556 i_uid_write(ino, st.uid);
557 i_gid_write(ino, st.gid);
558 ino->i_atime = st.atime;
559 ino->i_mtime = st.mtime;
560 ino->i_ctime = st.ctime;
561 ino->i_size = st.size;
562 ino->i_blocks = st.blocks;
563 return 0;
564}
565
566static int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
567 bool excl)
568{
569 struct inode *inode;
570 char *name;
571 int error, fd;
572
573 inode = hostfs_iget(dir->i_sb);
574 if (IS_ERR(inode)) {
575 error = PTR_ERR(inode);
576 goto out;
577 }
578
579 error = -ENOMEM;
580 name = dentry_name(dentry);
581 if (name == NULL)
582 goto out_put;
583
584 fd = file_create(name, mode & 0777);
585 if (fd < 0)
586 error = fd;
587 else
588 error = read_name(inode, name);
589
590 __putname(name);
591 if (error)
592 goto out_put;
593
594 HOSTFS_I(inode)->fd = fd;
595 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
596 d_instantiate(dentry, inode);
597 return 0;
598
599 out_put:
600 iput(inode);
601 out:
602 return error;
603}
604
605static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
606 unsigned int flags)
607{
608 struct inode *inode;
609 char *name;
610 int err;
611
612 inode = hostfs_iget(ino->i_sb);
613 if (IS_ERR(inode)) {
614 err = PTR_ERR(inode);
615 goto out;
616 }
617
618 err = -ENOMEM;
619 name = dentry_name(dentry);
620 if (name == NULL)
621 goto out_put;
622
623 err = read_name(inode, name);
624
625 __putname(name);
626 if (err == -ENOENT) {
627 iput(inode);
628 inode = NULL;
629 }
630 else if (err)
631 goto out_put;
632
633 d_add(dentry, inode);
634 return NULL;
635
636 out_put:
637 iput(inode);
638 out:
639 return ERR_PTR(err);
640}
641
642static int hostfs_link(struct dentry *to, struct inode *ino,
643 struct dentry *from)
644{
645 char *from_name, *to_name;
646 int err;
647
648 if ((from_name = dentry_name(from)) == NULL)
649 return -ENOMEM;
650 to_name = dentry_name(to);
651 if (to_name == NULL) {
652 __putname(from_name);
653 return -ENOMEM;
654 }
655 err = link_file(to_name, from_name);
656 __putname(from_name);
657 __putname(to_name);
658 return err;
659}
660
661static int hostfs_unlink(struct inode *ino, struct dentry *dentry)
662{
663 char *file;
664 int err;
665
666 if (append)
667 return -EPERM;
668
669 if ((file = dentry_name(dentry)) == NULL)
670 return -ENOMEM;
671
672 err = unlink_file(file);
673 __putname(file);
674 return err;
675}
676
677static int hostfs_symlink(struct inode *ino, struct dentry *dentry,
678 const char *to)
679{
680 char *file;
681 int err;
682
683 if ((file = dentry_name(dentry)) == NULL)
684 return -ENOMEM;
685 err = make_symlink(file, to);
686 __putname(file);
687 return err;
688}
689
690static int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode)
691{
692 char *file;
693 int err;
694
695 if ((file = dentry_name(dentry)) == NULL)
696 return -ENOMEM;
697 err = do_mkdir(file, mode);
698 __putname(file);
699 return err;
700}
701
702static int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
703{
704 char *file;
705 int err;
706
707 if ((file = dentry_name(dentry)) == NULL)
708 return -ENOMEM;
709 err = do_rmdir(file);
710 __putname(file);
711 return err;
712}
713
714static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
715{
716 struct inode *inode;
717 char *name;
718 int err;
719
720 inode = hostfs_iget(dir->i_sb);
721 if (IS_ERR(inode)) {
722 err = PTR_ERR(inode);
723 goto out;
724 }
725
726 err = -ENOMEM;
727 name = dentry_name(dentry);
728 if (name == NULL)
729 goto out_put;
730
731 init_special_inode(inode, mode, dev);
732 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
733 if (err)
734 goto out_free;
735
736 err = read_name(inode, name);
737 __putname(name);
738 if (err)
739 goto out_put;
740
741 d_instantiate(dentry, inode);
742 return 0;
743
744 out_free:
745 __putname(name);
746 out_put:
747 iput(inode);
748 out:
749 return err;
750}
751
752static int hostfs_rename2(struct inode *old_dir, struct dentry *old_dentry,
753 struct inode *new_dir, struct dentry *new_dentry,
754 unsigned int flags)
755{
756 char *old_name, *new_name;
757 int err;
758
759 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
760 return -EINVAL;
761
762 old_name = dentry_name(old_dentry);
763 if (old_name == NULL)
764 return -ENOMEM;
765 new_name = dentry_name(new_dentry);
766 if (new_name == NULL) {
767 __putname(old_name);
768 return -ENOMEM;
769 }
770 if (!flags)
771 err = rename_file(old_name, new_name);
772 else
773 err = rename2_file(old_name, new_name, flags);
774
775 __putname(old_name);
776 __putname(new_name);
777 return err;
778}
779
780static int hostfs_permission(struct inode *ino, int desired)
781{
782 char *name;
783 int r = 0, w = 0, x = 0, err;
784
785 if (desired & MAY_NOT_BLOCK)
786 return -ECHILD;
787
788 if (desired & MAY_READ) r = 1;
789 if (desired & MAY_WRITE) w = 1;
790 if (desired & MAY_EXEC) x = 1;
791 name = inode_name(ino);
792 if (name == NULL)
793 return -ENOMEM;
794
795 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
796 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
797 err = 0;
798 else
799 err = access_file(name, r, w, x);
800 __putname(name);
801 if (!err)
802 err = generic_permission(ino, desired);
803 return err;
804}
805
806static int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
807{
808 struct inode *inode = d_inode(dentry);
809 struct hostfs_iattr attrs;
810 char *name;
811 int err;
812
813 int fd = HOSTFS_I(inode)->fd;
814
815 err = inode_change_ok(inode, attr);
816 if (err)
817 return err;
818
819 if (append)
820 attr->ia_valid &= ~ATTR_SIZE;
821
822 attrs.ia_valid = 0;
823 if (attr->ia_valid & ATTR_MODE) {
824 attrs.ia_valid |= HOSTFS_ATTR_MODE;
825 attrs.ia_mode = attr->ia_mode;
826 }
827 if (attr->ia_valid & ATTR_UID) {
828 attrs.ia_valid |= HOSTFS_ATTR_UID;
829 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid);
830 }
831 if (attr->ia_valid & ATTR_GID) {
832 attrs.ia_valid |= HOSTFS_ATTR_GID;
833 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid);
834 }
835 if (attr->ia_valid & ATTR_SIZE) {
836 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
837 attrs.ia_size = attr->ia_size;
838 }
839 if (attr->ia_valid & ATTR_ATIME) {
840 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
841 attrs.ia_atime = attr->ia_atime;
842 }
843 if (attr->ia_valid & ATTR_MTIME) {
844 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
845 attrs.ia_mtime = attr->ia_mtime;
846 }
847 if (attr->ia_valid & ATTR_CTIME) {
848 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
849 attrs.ia_ctime = attr->ia_ctime;
850 }
851 if (attr->ia_valid & ATTR_ATIME_SET) {
852 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
853 }
854 if (attr->ia_valid & ATTR_MTIME_SET) {
855 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
856 }
857 name = dentry_name(dentry);
858 if (name == NULL)
859 return -ENOMEM;
860 err = set_attr(name, &attrs, fd);
861 __putname(name);
862 if (err)
863 return err;
864
865 if ((attr->ia_valid & ATTR_SIZE) &&
866 attr->ia_size != i_size_read(inode))
867 truncate_setsize(inode, attr->ia_size);
868
869 setattr_copy(inode, attr);
870 mark_inode_dirty(inode);
871 return 0;
872}
873
874static const struct inode_operations hostfs_iops = {
875 .permission = hostfs_permission,
876 .setattr = hostfs_setattr,
877};
878
879static const struct inode_operations hostfs_dir_iops = {
880 .create = hostfs_create,
881 .lookup = hostfs_lookup,
882 .link = hostfs_link,
883 .unlink = hostfs_unlink,
884 .symlink = hostfs_symlink,
885 .mkdir = hostfs_mkdir,
886 .rmdir = hostfs_rmdir,
887 .mknod = hostfs_mknod,
888 .rename2 = hostfs_rename2,
889 .permission = hostfs_permission,
890 .setattr = hostfs_setattr,
891};
892
893static const char *hostfs_get_link(struct dentry *dentry,
894 struct inode *inode,
895 struct delayed_call *done)
896{
897 char *link;
898 if (!dentry)
899 return ERR_PTR(-ECHILD);
900 link = kmalloc(PATH_MAX, GFP_KERNEL);
901 if (link) {
902 char *path = dentry_name(dentry);
903 int err = -ENOMEM;
904 if (path) {
905 err = hostfs_do_readlink(path, link, PATH_MAX);
906 if (err == PATH_MAX)
907 err = -E2BIG;
908 __putname(path);
909 }
910 if (err < 0) {
911 kfree(link);
912 return ERR_PTR(err);
913 }
914 } else {
915 return ERR_PTR(-ENOMEM);
916 }
917
918 set_delayed_call(done, kfree_link, link);
919 return link;
920}
921
922static const struct inode_operations hostfs_link_iops = {
923 .readlink = generic_readlink,
924 .get_link = hostfs_get_link,
925};
926
927static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
928{
929 struct inode *root_inode;
930 char *host_root_path, *req_root = d;
931 int err;
932
933 sb->s_blocksize = 1024;
934 sb->s_blocksize_bits = 10;
935 sb->s_magic = HOSTFS_SUPER_MAGIC;
936 sb->s_op = &hostfs_sbops;
937 sb->s_d_op = &simple_dentry_operations;
938 sb->s_maxbytes = MAX_LFS_FILESIZE;
939
940 /* NULL is printed as <NULL> by sprintf: avoid that. */
941 if (req_root == NULL)
942 req_root = "";
943
944 err = -ENOMEM;
945 sb->s_fs_info = host_root_path =
946 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL);
947 if (host_root_path == NULL)
948 goto out;
949
950 sprintf(host_root_path, "%s/%s", root_ino, req_root);
951
952 root_inode = new_inode(sb);
953 if (!root_inode)
954 goto out;
955
956 err = read_name(root_inode, host_root_path);
957 if (err)
958 goto out_put;
959
960 if (S_ISLNK(root_inode->i_mode)) {
961 char *name = follow_link(host_root_path);
962 if (IS_ERR(name))
963 err = PTR_ERR(name);
964 else
965 err = read_name(root_inode, name);
966 kfree(name);
967 if (err)
968 goto out_put;
969 }
970
971 err = -ENOMEM;
972 sb->s_root = d_make_root(root_inode);
973 if (sb->s_root == NULL)
974 goto out;
975
976 return 0;
977
978out_put:
979 iput(root_inode);
980out:
981 return err;
982}
983
984static struct dentry *hostfs_read_sb(struct file_system_type *type,
985 int flags, const char *dev_name,
986 void *data)
987{
988 return mount_nodev(type, flags, data, hostfs_fill_sb_common);
989}
990
991static void hostfs_kill_sb(struct super_block *s)
992{
993 kill_anon_super(s);
994 kfree(s->s_fs_info);
995}
996
997static struct file_system_type hostfs_type = {
998 .owner = THIS_MODULE,
999 .name = "hostfs",
1000 .mount = hostfs_read_sb,
1001 .kill_sb = hostfs_kill_sb,
1002 .fs_flags = 0,
1003};
1004MODULE_ALIAS_FS("hostfs");
1005
1006static int __init init_hostfs(void)
1007{
1008 return register_filesystem(&hostfs_type);
1009}
1010
1011static void __exit exit_hostfs(void)
1012{
1013 unregister_filesystem(&hostfs_type);
1014}
1015
1016module_init(init_hostfs)
1017module_exit(exit_hostfs)
1018MODULE_LICENSE("GPL");