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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 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_free_inode(struct inode *inode)
247{
248 kfree(HOSTFS_I(inode));
249}
250
251static int hostfs_show_options(struct seq_file *seq, struct dentry *root)
252{
253 const char *root_path = root->d_sb->s_fs_info;
254 size_t offset = strlen(root_ino) + 1;
255
256 if (strlen(root_path) > offset)
257 seq_show_option(seq, root_path + offset, NULL);
258
259 if (append)
260 seq_puts(seq, ",append");
261
262 return 0;
263}
264
265static const struct super_operations hostfs_sbops = {
266 .alloc_inode = hostfs_alloc_inode,
267 .free_inode = hostfs_free_inode,
268 .evict_inode = hostfs_evict_inode,
269 .statfs = hostfs_statfs,
270 .show_options = hostfs_show_options,
271};
272
273static int hostfs_readdir(struct file *file, struct dir_context *ctx)
274{
275 void *dir;
276 char *name;
277 unsigned long long next, ino;
278 int error, len;
279 unsigned int type;
280
281 name = dentry_name(file->f_path.dentry);
282 if (name == NULL)
283 return -ENOMEM;
284 dir = open_dir(name, &error);
285 __putname(name);
286 if (dir == NULL)
287 return -error;
288 next = ctx->pos;
289 seek_dir(dir, next);
290 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) {
291 if (!dir_emit(ctx, name, len, ino, type))
292 break;
293 ctx->pos = next;
294 }
295 close_dir(dir);
296 return 0;
297}
298
299static int hostfs_open(struct inode *ino, struct file *file)
300{
301 char *name;
302 fmode_t mode;
303 int err;
304 int r, w, fd;
305
306 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
307 if ((mode & HOSTFS_I(ino)->mode) == mode)
308 return 0;
309
310 mode |= HOSTFS_I(ino)->mode;
311
312retry:
313 r = w = 0;
314
315 if (mode & FMODE_READ)
316 r = 1;
317 if (mode & FMODE_WRITE)
318 r = w = 1;
319
320 name = dentry_name(file->f_path.dentry);
321 if (name == NULL)
322 return -ENOMEM;
323
324 fd = open_file(name, r, w, append);
325 __putname(name);
326 if (fd < 0)
327 return fd;
328
329 mutex_lock(&HOSTFS_I(ino)->open_mutex);
330 /* somebody else had handled it first? */
331 if ((mode & HOSTFS_I(ino)->mode) == mode) {
332 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
333 close_file(&fd);
334 return 0;
335 }
336 if ((mode | HOSTFS_I(ino)->mode) != mode) {
337 mode |= HOSTFS_I(ino)->mode;
338 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
339 close_file(&fd);
340 goto retry;
341 }
342 if (HOSTFS_I(ino)->fd == -1) {
343 HOSTFS_I(ino)->fd = fd;
344 } else {
345 err = replace_file(fd, HOSTFS_I(ino)->fd);
346 close_file(&fd);
347 if (err < 0) {
348 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
349 return err;
350 }
351 }
352 HOSTFS_I(ino)->mode = mode;
353 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
354
355 return 0;
356}
357
358static int hostfs_file_release(struct inode *inode, struct file *file)
359{
360 filemap_write_and_wait(inode->i_mapping);
361
362 return 0;
363}
364
365static int hostfs_fsync(struct file *file, loff_t start, loff_t end,
366 int datasync)
367{
368 struct inode *inode = file->f_mapping->host;
369 int ret;
370
371 ret = file_write_and_wait_range(file, start, end);
372 if (ret)
373 return ret;
374
375 inode_lock(inode);
376 ret = fsync_file(HOSTFS_I(inode)->fd, datasync);
377 inode_unlock(inode);
378
379 return ret;
380}
381
382static const struct file_operations hostfs_file_fops = {
383 .llseek = generic_file_llseek,
384 .splice_read = generic_file_splice_read,
385 .read_iter = generic_file_read_iter,
386 .write_iter = generic_file_write_iter,
387 .mmap = generic_file_mmap,
388 .open = hostfs_open,
389 .release = hostfs_file_release,
390 .fsync = hostfs_fsync,
391};
392
393static const struct file_operations hostfs_dir_fops = {
394 .llseek = generic_file_llseek,
395 .iterate_shared = hostfs_readdir,
396 .read = generic_read_dir,
397 .open = hostfs_open,
398 .fsync = hostfs_fsync,
399};
400
401static int hostfs_writepage(struct page *page, struct writeback_control *wbc)
402{
403 struct address_space *mapping = page->mapping;
404 struct inode *inode = mapping->host;
405 char *buffer;
406 loff_t base = page_offset(page);
407 int count = PAGE_SIZE;
408 int end_index = inode->i_size >> PAGE_SHIFT;
409 int err;
410
411 if (page->index >= end_index)
412 count = inode->i_size & (PAGE_SIZE-1);
413
414 buffer = kmap(page);
415
416 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
417 if (err != count) {
418 ClearPageUptodate(page);
419 goto out;
420 }
421
422 if (base > inode->i_size)
423 inode->i_size = base;
424
425 if (PageError(page))
426 ClearPageError(page);
427 err = 0;
428
429 out:
430 kunmap(page);
431
432 unlock_page(page);
433 return err;
434}
435
436static int hostfs_readpage(struct file *file, struct page *page)
437{
438 char *buffer;
439 loff_t start = page_offset(page);
440 int bytes_read, ret = 0;
441
442 buffer = kmap(page);
443 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
444 PAGE_SIZE);
445 if (bytes_read < 0) {
446 ClearPageUptodate(page);
447 SetPageError(page);
448 ret = bytes_read;
449 goto out;
450 }
451
452 memset(buffer + bytes_read, 0, PAGE_SIZE - bytes_read);
453
454 ClearPageError(page);
455 SetPageUptodate(page);
456
457 out:
458 flush_dcache_page(page);
459 kunmap(page);
460 unlock_page(page);
461 return ret;
462}
463
464static int hostfs_write_begin(struct file *file, struct address_space *mapping,
465 loff_t pos, unsigned len, unsigned flags,
466 struct page **pagep, void **fsdata)
467{
468 pgoff_t index = pos >> PAGE_SHIFT;
469
470 *pagep = grab_cache_page_write_begin(mapping, index, flags);
471 if (!*pagep)
472 return -ENOMEM;
473 return 0;
474}
475
476static int hostfs_write_end(struct file *file, struct address_space *mapping,
477 loff_t pos, unsigned len, unsigned copied,
478 struct page *page, void *fsdata)
479{
480 struct inode *inode = mapping->host;
481 void *buffer;
482 unsigned from = pos & (PAGE_SIZE - 1);
483 int err;
484
485 buffer = kmap(page);
486 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
487 kunmap(page);
488
489 if (!PageUptodate(page) && err == PAGE_SIZE)
490 SetPageUptodate(page);
491
492 /*
493 * If err > 0, write_file has added err to pos, so we are comparing
494 * i_size against the last byte written.
495 */
496 if (err > 0 && (pos > inode->i_size))
497 inode->i_size = pos;
498 unlock_page(page);
499 put_page(page);
500
501 return err;
502}
503
504static const struct address_space_operations hostfs_aops = {
505 .writepage = hostfs_writepage,
506 .readpage = hostfs_readpage,
507 .set_page_dirty = __set_page_dirty_nobuffers,
508 .write_begin = hostfs_write_begin,
509 .write_end = hostfs_write_end,
510};
511
512static int read_name(struct inode *ino, char *name)
513{
514 dev_t rdev;
515 struct hostfs_stat st;
516 int err = stat_file(name, &st, -1);
517 if (err)
518 return err;
519
520 /* Reencode maj and min with the kernel encoding.*/
521 rdev = MKDEV(st.maj, st.min);
522
523 switch (st.mode & S_IFMT) {
524 case S_IFLNK:
525 ino->i_op = &hostfs_link_iops;
526 break;
527 case S_IFDIR:
528 ino->i_op = &hostfs_dir_iops;
529 ino->i_fop = &hostfs_dir_fops;
530 break;
531 case S_IFCHR:
532 case S_IFBLK:
533 case S_IFIFO:
534 case S_IFSOCK:
535 init_special_inode(ino, st.mode & S_IFMT, rdev);
536 ino->i_op = &hostfs_iops;
537 break;
538 case S_IFREG:
539 ino->i_op = &hostfs_iops;
540 ino->i_fop = &hostfs_file_fops;
541 ino->i_mapping->a_ops = &hostfs_aops;
542 break;
543 default:
544 return -EIO;
545 }
546
547 ino->i_ino = st.ino;
548 ino->i_mode = st.mode;
549 set_nlink(ino, st.nlink);
550 i_uid_write(ino, st.uid);
551 i_gid_write(ino, st.gid);
552 ino->i_atime = timespec_to_timespec64(st.atime);
553 ino->i_mtime = timespec_to_timespec64(st.mtime);
554 ino->i_ctime = timespec_to_timespec64(st.ctime);
555 ino->i_size = st.size;
556 ino->i_blocks = st.blocks;
557 return 0;
558}
559
560static int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
561 bool excl)
562{
563 struct inode *inode;
564 char *name;
565 int error, fd;
566
567 inode = hostfs_iget(dir->i_sb);
568 if (IS_ERR(inode)) {
569 error = PTR_ERR(inode);
570 goto out;
571 }
572
573 error = -ENOMEM;
574 name = dentry_name(dentry);
575 if (name == NULL)
576 goto out_put;
577
578 fd = file_create(name, mode & 0777);
579 if (fd < 0)
580 error = fd;
581 else
582 error = read_name(inode, name);
583
584 __putname(name);
585 if (error)
586 goto out_put;
587
588 HOSTFS_I(inode)->fd = fd;
589 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
590 d_instantiate(dentry, inode);
591 return 0;
592
593 out_put:
594 iput(inode);
595 out:
596 return error;
597}
598
599static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
600 unsigned int flags)
601{
602 struct inode *inode;
603 char *name;
604 int err;
605
606 inode = hostfs_iget(ino->i_sb);
607 if (IS_ERR(inode))
608 goto out;
609
610 err = -ENOMEM;
611 name = dentry_name(dentry);
612 if (name) {
613 err = read_name(inode, name);
614 __putname(name);
615 }
616 if (err) {
617 iput(inode);
618 inode = (err == -ENOENT) ? NULL : ERR_PTR(err);
619 }
620 out:
621 return d_splice_alias(inode, dentry);
622}
623
624static int hostfs_link(struct dentry *to, struct inode *ino,
625 struct dentry *from)
626{
627 char *from_name, *to_name;
628 int err;
629
630 if ((from_name = dentry_name(from)) == NULL)
631 return -ENOMEM;
632 to_name = dentry_name(to);
633 if (to_name == NULL) {
634 __putname(from_name);
635 return -ENOMEM;
636 }
637 err = link_file(to_name, from_name);
638 __putname(from_name);
639 __putname(to_name);
640 return err;
641}
642
643static int hostfs_unlink(struct inode *ino, struct dentry *dentry)
644{
645 char *file;
646 int err;
647
648 if (append)
649 return -EPERM;
650
651 if ((file = dentry_name(dentry)) == NULL)
652 return -ENOMEM;
653
654 err = unlink_file(file);
655 __putname(file);
656 return err;
657}
658
659static int hostfs_symlink(struct inode *ino, struct dentry *dentry,
660 const char *to)
661{
662 char *file;
663 int err;
664
665 if ((file = dentry_name(dentry)) == NULL)
666 return -ENOMEM;
667 err = make_symlink(file, to);
668 __putname(file);
669 return err;
670}
671
672static int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode)
673{
674 char *file;
675 int err;
676
677 if ((file = dentry_name(dentry)) == NULL)
678 return -ENOMEM;
679 err = do_mkdir(file, mode);
680 __putname(file);
681 return err;
682}
683
684static int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
685{
686 char *file;
687 int err;
688
689 if ((file = dentry_name(dentry)) == NULL)
690 return -ENOMEM;
691 err = hostfs_do_rmdir(file);
692 __putname(file);
693 return err;
694}
695
696static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
697{
698 struct inode *inode;
699 char *name;
700 int err;
701
702 inode = hostfs_iget(dir->i_sb);
703 if (IS_ERR(inode)) {
704 err = PTR_ERR(inode);
705 goto out;
706 }
707
708 err = -ENOMEM;
709 name = dentry_name(dentry);
710 if (name == NULL)
711 goto out_put;
712
713 init_special_inode(inode, mode, dev);
714 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
715 if (err)
716 goto out_free;
717
718 err = read_name(inode, name);
719 __putname(name);
720 if (err)
721 goto out_put;
722
723 d_instantiate(dentry, inode);
724 return 0;
725
726 out_free:
727 __putname(name);
728 out_put:
729 iput(inode);
730 out:
731 return err;
732}
733
734static int hostfs_rename2(struct inode *old_dir, struct dentry *old_dentry,
735 struct inode *new_dir, struct dentry *new_dentry,
736 unsigned int flags)
737{
738 char *old_name, *new_name;
739 int err;
740
741 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
742 return -EINVAL;
743
744 old_name = dentry_name(old_dentry);
745 if (old_name == NULL)
746 return -ENOMEM;
747 new_name = dentry_name(new_dentry);
748 if (new_name == NULL) {
749 __putname(old_name);
750 return -ENOMEM;
751 }
752 if (!flags)
753 err = rename_file(old_name, new_name);
754 else
755 err = rename2_file(old_name, new_name, flags);
756
757 __putname(old_name);
758 __putname(new_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 = d_inode(dentry);
791 struct hostfs_iattr attrs;
792 char *name;
793 int err;
794
795 int fd = HOSTFS_I(inode)->fd;
796
797 err = setattr_prepare(dentry, 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 = timespec64_to_timespec(attr->ia_atime);
824 }
825 if (attr->ia_valid & ATTR_MTIME) {
826 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
827 attrs.ia_mtime = timespec64_to_timespec(attr->ia_mtime);
828 }
829 if (attr->ia_valid & ATTR_CTIME) {
830 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
831 attrs.ia_ctime = timespec64_to_timespec(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_rename2,
871 .permission = hostfs_permission,
872 .setattr = hostfs_setattr,
873};
874
875static const char *hostfs_get_link(struct dentry *dentry,
876 struct inode *inode,
877 struct delayed_call *done)
878{
879 char *link;
880 if (!dentry)
881 return ERR_PTR(-ECHILD);
882 link = kmalloc(PATH_MAX, GFP_KERNEL);
883 if (link) {
884 char *path = dentry_name(dentry);
885 int err = -ENOMEM;
886 if (path) {
887 err = hostfs_do_readlink(path, link, PATH_MAX);
888 if (err == PATH_MAX)
889 err = -E2BIG;
890 __putname(path);
891 }
892 if (err < 0) {
893 kfree(link);
894 return ERR_PTR(err);
895 }
896 } else {
897 return ERR_PTR(-ENOMEM);
898 }
899
900 set_delayed_call(done, kfree_link, link);
901 return link;
902}
903
904static const struct inode_operations hostfs_link_iops = {
905 .get_link = hostfs_get_link,
906};
907
908static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
909{
910 struct inode *root_inode;
911 char *host_root_path, *req_root = d;
912 int err;
913
914 sb->s_blocksize = 1024;
915 sb->s_blocksize_bits = 10;
916 sb->s_magic = HOSTFS_SUPER_MAGIC;
917 sb->s_op = &hostfs_sbops;
918 sb->s_d_op = &simple_dentry_operations;
919 sb->s_maxbytes = MAX_LFS_FILESIZE;
920
921 /* NULL is printed as <NULL> by sprintf: avoid that. */
922 if (req_root == NULL)
923 req_root = "";
924
925 err = -ENOMEM;
926 sb->s_fs_info = host_root_path =
927 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL);
928 if (host_root_path == NULL)
929 goto out;
930
931 sprintf(host_root_path, "%s/%s", root_ino, req_root);
932
933 root_inode = new_inode(sb);
934 if (!root_inode)
935 goto out;
936
937 err = read_name(root_inode, host_root_path);
938 if (err)
939 goto out_put;
940
941 if (S_ISLNK(root_inode->i_mode)) {
942 char *name = follow_link(host_root_path);
943 if (IS_ERR(name)) {
944 err = PTR_ERR(name);
945 goto out_put;
946 }
947 err = read_name(root_inode, name);
948 kfree(name);
949 if (err)
950 goto out_put;
951 }
952
953 err = -ENOMEM;
954 sb->s_root = d_make_root(root_inode);
955 if (sb->s_root == NULL)
956 goto out;
957
958 return 0;
959
960out_put:
961 iput(root_inode);
962out:
963 return err;
964}
965
966static struct dentry *hostfs_read_sb(struct file_system_type *type,
967 int flags, const char *dev_name,
968 void *data)
969{
970 return mount_nodev(type, flags, data, hostfs_fill_sb_common);
971}
972
973static void hostfs_kill_sb(struct super_block *s)
974{
975 kill_anon_super(s);
976 kfree(s->s_fs_info);
977}
978
979static struct file_system_type hostfs_type = {
980 .owner = THIS_MODULE,
981 .name = "hostfs",
982 .mount = hostfs_read_sb,
983 .kill_sb = hostfs_kill_sb,
984 .fs_flags = 0,
985};
986MODULE_ALIAS_FS("hostfs");
987
988static int __init init_hostfs(void)
989{
990 return register_filesystem(&hostfs_type);
991}
992
993static void __exit exit_hostfs(void)
994{
995 unregister_filesystem(&hostfs_type);
996}
997
998module_init(init_hostfs)
999module_exit(exit_hostfs)
1000MODULE_LICENSE("GPL");