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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/module.h>
11#include <linux/mm.h>
12#include <linux/pagemap.h>
13#include <linux/statfs.h>
14#include <linux/slab.h>
15#include <linux/seq_file.h>
16#include <linux/mount.h>
17#include <linux/namei.h>
18#include "hostfs.h"
19#include "init.h"
20#include "kern.h"
21
22struct hostfs_inode_info {
23 int fd;
24 fmode_t mode;
25 struct inode vfs_inode;
26};
27
28static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
29{
30 return list_entry(inode, struct hostfs_inode_info, vfs_inode);
31}
32
33#define FILE_HOSTFS_I(file) HOSTFS_I((file)->f_path.dentry->d_inode)
34
35static int hostfs_d_delete(const struct dentry *dentry)
36{
37 return 1;
38}
39
40static const struct dentry_operations hostfs_dentry_ops = {
41 .d_delete = hostfs_d_delete,
42};
43
44/* Changed in hostfs_args before the kernel starts running */
45static char *root_ino = "";
46static int append = 0;
47
48#define HOSTFS_SUPER_MAGIC 0x00c0ffee
49
50static const struct inode_operations hostfs_iops;
51static const struct inode_operations hostfs_dir_iops;
52static const struct inode_operations hostfs_link_iops;
53
54#ifndef MODULE
55static int __init hostfs_args(char *options, int *add)
56{
57 char *ptr;
58
59 ptr = strchr(options, ',');
60 if (ptr != NULL)
61 *ptr++ = '\0';
62 if (*options != '\0')
63 root_ino = options;
64
65 options = ptr;
66 while (options) {
67 ptr = strchr(options, ',');
68 if (ptr != NULL)
69 *ptr++ = '\0';
70 if (*options != '\0') {
71 if (!strcmp(options, "append"))
72 append = 1;
73 else printf("hostfs_args - unsupported option - %s\n",
74 options);
75 }
76 options = ptr;
77 }
78 return 0;
79}
80
81__uml_setup("hostfs=", hostfs_args,
82"hostfs=<root dir>,<flags>,...\n"
83" This is used to set hostfs parameters. The root directory argument\n"
84" is used to confine all hostfs mounts to within the specified directory\n"
85" tree on the host. If this isn't specified, then a user inside UML can\n"
86" mount anything on the host that's accessible to the user that's running\n"
87" it.\n"
88" The only flag currently supported is 'append', which specifies that all\n"
89" files opened by hostfs will be opened in append mode.\n\n"
90);
91#endif
92
93static char *__dentry_name(struct dentry *dentry, char *name)
94{
95 char *p = dentry_path_raw(dentry, name, PATH_MAX);
96 char *root;
97 size_t len;
98
99 root = dentry->d_sb->s_fs_info;
100 len = strlen(root);
101 if (IS_ERR(p)) {
102 __putname(name);
103 return NULL;
104 }
105 strlcpy(name, root, PATH_MAX);
106 if (len > p - name) {
107 __putname(name);
108 return NULL;
109 }
110 if (p > name + len) {
111 char *s = name + len;
112 while ((*s++ = *p++) != '\0')
113 ;
114 }
115 return name;
116}
117
118static char *dentry_name(struct dentry *dentry)
119{
120 char *name = __getname();
121 if (!name)
122 return NULL;
123
124 return __dentry_name(dentry, name); /* will unlock */
125}
126
127static char *inode_name(struct inode *ino)
128{
129 struct dentry *dentry;
130 char *name;
131
132 dentry = d_find_alias(ino);
133 if (!dentry)
134 return NULL;
135
136 name = dentry_name(dentry);
137
138 dput(dentry);
139
140 return name;
141}
142
143static char *follow_link(char *link)
144{
145 int len, n;
146 char *name, *resolved, *end;
147
148 len = 64;
149 while (1) {
150 n = -ENOMEM;
151 name = kmalloc(len, GFP_KERNEL);
152 if (name == NULL)
153 goto out;
154
155 n = hostfs_do_readlink(link, name, len);
156 if (n < len)
157 break;
158 len *= 2;
159 kfree(name);
160 }
161 if (n < 0)
162 goto out_free;
163
164 if (*name == '/')
165 return name;
166
167 end = strrchr(link, '/');
168 if (end == NULL)
169 return name;
170
171 *(end + 1) = '\0';
172 len = strlen(link) + strlen(name) + 1;
173
174 resolved = kmalloc(len, GFP_KERNEL);
175 if (resolved == NULL) {
176 n = -ENOMEM;
177 goto out_free;
178 }
179
180 sprintf(resolved, "%s%s", link, name);
181 kfree(name);
182 kfree(link);
183 return resolved;
184
185 out_free:
186 kfree(name);
187 out:
188 return ERR_PTR(n);
189}
190
191static struct inode *hostfs_iget(struct super_block *sb)
192{
193 struct inode *inode = new_inode(sb);
194 if (!inode)
195 return ERR_PTR(-ENOMEM);
196 return inode;
197}
198
199int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
200{
201 /*
202 * do_statfs uses struct statfs64 internally, but the linux kernel
203 * struct statfs still has 32-bit versions for most of these fields,
204 * so we convert them here
205 */
206 int err;
207 long long f_blocks;
208 long long f_bfree;
209 long long f_bavail;
210 long long f_files;
211 long long f_ffree;
212
213 err = do_statfs(dentry->d_sb->s_fs_info,
214 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
215 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
216 &sf->f_namelen);
217 if (err)
218 return err;
219 sf->f_blocks = f_blocks;
220 sf->f_bfree = f_bfree;
221 sf->f_bavail = f_bavail;
222 sf->f_files = f_files;
223 sf->f_ffree = f_ffree;
224 sf->f_type = HOSTFS_SUPER_MAGIC;
225 return 0;
226}
227
228static struct inode *hostfs_alloc_inode(struct super_block *sb)
229{
230 struct hostfs_inode_info *hi;
231
232 hi = kzalloc(sizeof(*hi), GFP_KERNEL);
233 if (hi == NULL)
234 return NULL;
235 hi->fd = -1;
236 inode_init_once(&hi->vfs_inode);
237 return &hi->vfs_inode;
238}
239
240static void hostfs_evict_inode(struct inode *inode)
241{
242 truncate_inode_pages(&inode->i_data, 0);
243 end_writeback(inode);
244 if (HOSTFS_I(inode)->fd != -1) {
245 close_file(&HOSTFS_I(inode)->fd);
246 HOSTFS_I(inode)->fd = -1;
247 }
248}
249
250static void hostfs_i_callback(struct rcu_head *head)
251{
252 struct inode *inode = container_of(head, struct inode, i_rcu);
253 INIT_LIST_HEAD(&inode->i_dentry);
254 kfree(HOSTFS_I(inode));
255}
256
257static void hostfs_destroy_inode(struct inode *inode)
258{
259 call_rcu(&inode->i_rcu, hostfs_i_callback);
260}
261
262static int hostfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
263{
264 const char *root_path = vfs->mnt_sb->s_fs_info;
265 size_t offset = strlen(root_ino) + 1;
266
267 if (strlen(root_path) > offset)
268 seq_printf(seq, ",%s", root_path + offset);
269
270 return 0;
271}
272
273static const struct super_operations hostfs_sbops = {
274 .alloc_inode = hostfs_alloc_inode,
275 .destroy_inode = hostfs_destroy_inode,
276 .evict_inode = hostfs_evict_inode,
277 .statfs = hostfs_statfs,
278 .show_options = hostfs_show_options,
279};
280
281int hostfs_readdir(struct file *file, void *ent, filldir_t filldir)
282{
283 void *dir;
284 char *name;
285 unsigned long long next, ino;
286 int error, len;
287
288 name = dentry_name(file->f_path.dentry);
289 if (name == NULL)
290 return -ENOMEM;
291 dir = open_dir(name, &error);
292 __putname(name);
293 if (dir == NULL)
294 return -error;
295 next = file->f_pos;
296 while ((name = read_dir(dir, &next, &ino, &len)) != NULL) {
297 error = (*filldir)(ent, name, len, file->f_pos,
298 ino, DT_UNKNOWN);
299 if (error) break;
300 file->f_pos = next;
301 }
302 close_dir(dir);
303 return 0;
304}
305
306int hostfs_file_open(struct inode *ino, struct file *file)
307{
308 static DEFINE_MUTEX(open_mutex);
309 char *name;
310 fmode_t mode = 0;
311 int err;
312 int r = 0, w = 0, fd;
313
314 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
315 if ((mode & HOSTFS_I(ino)->mode) == mode)
316 return 0;
317
318 mode |= HOSTFS_I(ino)->mode;
319
320retry:
321 if (mode & FMODE_READ)
322 r = 1;
323 if (mode & FMODE_WRITE)
324 w = 1;
325 if (w)
326 r = 1;
327
328 name = dentry_name(file->f_path.dentry);
329 if (name == NULL)
330 return -ENOMEM;
331
332 fd = open_file(name, r, w, append);
333 __putname(name);
334 if (fd < 0)
335 return fd;
336
337 mutex_lock(&open_mutex);
338 /* somebody else had handled it first? */
339 if ((mode & HOSTFS_I(ino)->mode) == mode) {
340 mutex_unlock(&open_mutex);
341 return 0;
342 }
343 if ((mode | HOSTFS_I(ino)->mode) != mode) {
344 mode |= HOSTFS_I(ino)->mode;
345 mutex_unlock(&open_mutex);
346 close_file(&fd);
347 goto retry;
348 }
349 if (HOSTFS_I(ino)->fd == -1) {
350 HOSTFS_I(ino)->fd = fd;
351 } else {
352 err = replace_file(fd, HOSTFS_I(ino)->fd);
353 close_file(&fd);
354 if (err < 0) {
355 mutex_unlock(&open_mutex);
356 return err;
357 }
358 }
359 HOSTFS_I(ino)->mode = mode;
360 mutex_unlock(&open_mutex);
361
362 return 0;
363}
364
365int hostfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
366{
367 struct inode *inode = file->f_mapping->host;
368 int ret;
369
370 ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
371 if (ret)
372 return ret;
373
374 mutex_lock(&inode->i_mutex);
375 ret = fsync_file(HOSTFS_I(inode)->fd, datasync);
376 mutex_unlock(&inode->i_mutex);
377
378 return ret;
379}
380
381static const struct file_operations hostfs_file_fops = {
382 .llseek = generic_file_llseek,
383 .read = do_sync_read,
384 .splice_read = generic_file_splice_read,
385 .aio_read = generic_file_aio_read,
386 .aio_write = generic_file_aio_write,
387 .write = do_sync_write,
388 .mmap = generic_file_mmap,
389 .open = hostfs_file_open,
390 .release = NULL,
391 .fsync = hostfs_fsync,
392};
393
394static const struct file_operations hostfs_dir_fops = {
395 .llseek = generic_file_llseek,
396 .readdir = hostfs_readdir,
397 .read = generic_read_dir,
398};
399
400int hostfs_writepage(struct page *page, struct writeback_control *wbc)
401{
402 struct address_space *mapping = page->mapping;
403 struct inode *inode = mapping->host;
404 char *buffer;
405 unsigned long long base;
406 int count = PAGE_CACHE_SIZE;
407 int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
408 int err;
409
410 if (page->index >= end_index)
411 count = inode->i_size & (PAGE_CACHE_SIZE-1);
412
413 buffer = kmap(page);
414 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
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
436int hostfs_readpage(struct file *file, struct page *page)
437{
438 char *buffer;
439 long long start;
440 int err = 0;
441
442 start = (long long) page->index << PAGE_CACHE_SHIFT;
443 buffer = kmap(page);
444 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
445 PAGE_CACHE_SIZE);
446 if (err < 0)
447 goto out;
448
449 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
450
451 flush_dcache_page(page);
452 SetPageUptodate(page);
453 if (PageError(page)) ClearPageError(page);
454 err = 0;
455 out:
456 kunmap(page);
457 unlock_page(page);
458 return err;
459}
460
461int hostfs_write_begin(struct file *file, struct address_space *mapping,
462 loff_t pos, unsigned len, unsigned flags,
463 struct page **pagep, void **fsdata)
464{
465 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
466
467 *pagep = grab_cache_page_write_begin(mapping, index, flags);
468 if (!*pagep)
469 return -ENOMEM;
470 return 0;
471}
472
473int hostfs_write_end(struct file *file, struct address_space *mapping,
474 loff_t pos, unsigned len, unsigned copied,
475 struct page *page, void *fsdata)
476{
477 struct inode *inode = mapping->host;
478 void *buffer;
479 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
480 int err;
481
482 buffer = kmap(page);
483 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
484 kunmap(page);
485
486 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE)
487 SetPageUptodate(page);
488
489 /*
490 * If err > 0, write_file has added err to pos, so we are comparing
491 * i_size against the last byte written.
492 */
493 if (err > 0 && (pos > inode->i_size))
494 inode->i_size = pos;
495 unlock_page(page);
496 page_cache_release(page);
497
498 return err;
499}
500
501static const struct address_space_operations hostfs_aops = {
502 .writepage = hostfs_writepage,
503 .readpage = hostfs_readpage,
504 .set_page_dirty = __set_page_dirty_nobuffers,
505 .write_begin = hostfs_write_begin,
506 .write_end = hostfs_write_end,
507};
508
509static int read_name(struct inode *ino, char *name)
510{
511 dev_t rdev;
512 struct hostfs_stat st;
513 int err = stat_file(name, &st, -1);
514 if (err)
515 return err;
516
517 /* Reencode maj and min with the kernel encoding.*/
518 rdev = MKDEV(st.maj, st.min);
519
520 switch (st.mode & S_IFMT) {
521 case S_IFLNK:
522 ino->i_op = &hostfs_link_iops;
523 break;
524 case S_IFDIR:
525 ino->i_op = &hostfs_dir_iops;
526 ino->i_fop = &hostfs_dir_fops;
527 break;
528 case S_IFCHR:
529 case S_IFBLK:
530 case S_IFIFO:
531 case S_IFSOCK:
532 init_special_inode(ino, st.mode & S_IFMT, rdev);
533 ino->i_op = &hostfs_iops;
534 break;
535
536 default:
537 ino->i_op = &hostfs_iops;
538 ino->i_fop = &hostfs_file_fops;
539 ino->i_mapping->a_ops = &hostfs_aops;
540 }
541
542 ino->i_ino = st.ino;
543 ino->i_mode = st.mode;
544 ino->i_nlink = st.nlink;
545 ino->i_uid = st.uid;
546 ino->i_gid = st.gid;
547 ino->i_atime = st.atime;
548 ino->i_mtime = st.mtime;
549 ino->i_ctime = st.ctime;
550 ino->i_size = st.size;
551 ino->i_blocks = st.blocks;
552 return 0;
553}
554
555int hostfs_create(struct inode *dir, struct dentry *dentry, int mode,
556 struct nameidata *nd)
557{
558 struct inode *inode;
559 char *name;
560 int error, fd;
561
562 inode = hostfs_iget(dir->i_sb);
563 if (IS_ERR(inode)) {
564 error = PTR_ERR(inode);
565 goto out;
566 }
567
568 error = -ENOMEM;
569 name = dentry_name(dentry);
570 if (name == NULL)
571 goto out_put;
572
573 fd = file_create(name,
574 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
575 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
576 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
577 if (fd < 0)
578 error = fd;
579 else
580 error = read_name(inode, name);
581
582 __putname(name);
583 if (error)
584 goto out_put;
585
586 HOSTFS_I(inode)->fd = fd;
587 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
588 d_instantiate(dentry, inode);
589 return 0;
590
591 out_put:
592 iput(inode);
593 out:
594 return error;
595}
596
597struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
598 struct nameidata *nd)
599{
600 struct inode *inode;
601 char *name;
602 int err;
603
604 inode = hostfs_iget(ino->i_sb);
605 if (IS_ERR(inode)) {
606 err = PTR_ERR(inode);
607 goto out;
608 }
609
610 err = -ENOMEM;
611 name = dentry_name(dentry);
612 if (name == NULL)
613 goto out_put;
614
615 err = read_name(inode, name);
616
617 __putname(name);
618 if (err == -ENOENT) {
619 iput(inode);
620 inode = NULL;
621 }
622 else if (err)
623 goto out_put;
624
625 d_add(dentry, inode);
626 return NULL;
627
628 out_put:
629 iput(inode);
630 out:
631 return ERR_PTR(err);
632}
633
634int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from)
635{
636 char *from_name, *to_name;
637 int err;
638
639 if ((from_name = dentry_name(from)) == NULL)
640 return -ENOMEM;
641 to_name = dentry_name(to);
642 if (to_name == NULL) {
643 __putname(from_name);
644 return -ENOMEM;
645 }
646 err = link_file(to_name, from_name);
647 __putname(from_name);
648 __putname(to_name);
649 return err;
650}
651
652int hostfs_unlink(struct inode *ino, struct dentry *dentry)
653{
654 char *file;
655 int err;
656
657 if (append)
658 return -EPERM;
659
660 if ((file = dentry_name(dentry)) == NULL)
661 return -ENOMEM;
662
663 err = unlink_file(file);
664 __putname(file);
665 return err;
666}
667
668int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to)
669{
670 char *file;
671 int err;
672
673 if ((file = dentry_name(dentry)) == NULL)
674 return -ENOMEM;
675 err = make_symlink(file, to);
676 __putname(file);
677 return err;
678}
679
680int hostfs_mkdir(struct inode *ino, struct dentry *dentry, int mode)
681{
682 char *file;
683 int err;
684
685 if ((file = dentry_name(dentry)) == NULL)
686 return -ENOMEM;
687 err = do_mkdir(file, mode);
688 __putname(file);
689 return err;
690}
691
692int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
693{
694 char *file;
695 int err;
696
697 if ((file = dentry_name(dentry)) == NULL)
698 return -ENOMEM;
699 err = do_rmdir(file);
700 __putname(file);
701 return err;
702}
703
704int hostfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
705{
706 struct inode *inode;
707 char *name;
708 int err;
709
710 inode = hostfs_iget(dir->i_sb);
711 if (IS_ERR(inode)) {
712 err = PTR_ERR(inode);
713 goto out;
714 }
715
716 err = -ENOMEM;
717 name = dentry_name(dentry);
718 if (name == NULL)
719 goto out_put;
720
721 init_special_inode(inode, mode, dev);
722 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
723 if (!err)
724 goto out_free;
725
726 err = read_name(inode, name);
727 __putname(name);
728 if (err)
729 goto out_put;
730 if (err)
731 goto out_put;
732
733 d_instantiate(dentry, inode);
734 return 0;
735
736 out_free:
737 __putname(name);
738 out_put:
739 iput(inode);
740 out:
741 return err;
742}
743
744int hostfs_rename(struct inode *from_ino, struct dentry *from,
745 struct inode *to_ino, struct dentry *to)
746{
747 char *from_name, *to_name;
748 int err;
749
750 if ((from_name = dentry_name(from)) == NULL)
751 return -ENOMEM;
752 if ((to_name = dentry_name(to)) == NULL) {
753 __putname(from_name);
754 return -ENOMEM;
755 }
756 err = rename_file(from_name, to_name);
757 __putname(from_name);
758 __putname(to_name);
759 return err;
760}
761
762int 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
788int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
789{
790 struct inode *inode = dentry->d_inode;
791 struct hostfs_iattr attrs;
792 char *name;
793 int err;
794
795 int fd = HOSTFS_I(inode)->fd;
796
797 err = inode_change_ok(inode, attr);
798 if (err)
799 return err;
800
801 if (append)
802 attr->ia_valid &= ~ATTR_SIZE;
803
804 attrs.ia_valid = 0;
805 if (attr->ia_valid & ATTR_MODE) {
806 attrs.ia_valid |= HOSTFS_ATTR_MODE;
807 attrs.ia_mode = attr->ia_mode;
808 }
809 if (attr->ia_valid & ATTR_UID) {
810 attrs.ia_valid |= HOSTFS_ATTR_UID;
811 attrs.ia_uid = attr->ia_uid;
812 }
813 if (attr->ia_valid & ATTR_GID) {
814 attrs.ia_valid |= HOSTFS_ATTR_GID;
815 attrs.ia_gid = attr->ia_gid;
816 }
817 if (attr->ia_valid & ATTR_SIZE) {
818 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
819 attrs.ia_size = attr->ia_size;
820 }
821 if (attr->ia_valid & ATTR_ATIME) {
822 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
823 attrs.ia_atime = attr->ia_atime;
824 }
825 if (attr->ia_valid & ATTR_MTIME) {
826 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
827 attrs.ia_mtime = attr->ia_mtime;
828 }
829 if (attr->ia_valid & ATTR_CTIME) {
830 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
831 attrs.ia_ctime = attr->ia_ctime;
832 }
833 if (attr->ia_valid & ATTR_ATIME_SET) {
834 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
835 }
836 if (attr->ia_valid & ATTR_MTIME_SET) {
837 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
838 }
839 name = dentry_name(dentry);
840 if (name == NULL)
841 return -ENOMEM;
842 err = set_attr(name, &attrs, fd);
843 __putname(name);
844 if (err)
845 return err;
846
847 if ((attr->ia_valid & ATTR_SIZE) &&
848 attr->ia_size != i_size_read(inode)) {
849 int error;
850
851 error = vmtruncate(inode, attr->ia_size);
852 if (err)
853 return err;
854 }
855
856 setattr_copy(inode, attr);
857 mark_inode_dirty(inode);
858 return 0;
859}
860
861static const struct inode_operations hostfs_iops = {
862 .create = hostfs_create,
863 .link = hostfs_link,
864 .unlink = hostfs_unlink,
865 .symlink = hostfs_symlink,
866 .mkdir = hostfs_mkdir,
867 .rmdir = hostfs_rmdir,
868 .mknod = hostfs_mknod,
869 .rename = hostfs_rename,
870 .permission = hostfs_permission,
871 .setattr = hostfs_setattr,
872};
873
874static const struct inode_operations hostfs_dir_iops = {
875 .create = hostfs_create,
876 .lookup = hostfs_lookup,
877 .link = hostfs_link,
878 .unlink = hostfs_unlink,
879 .symlink = hostfs_symlink,
880 .mkdir = hostfs_mkdir,
881 .rmdir = hostfs_rmdir,
882 .mknod = hostfs_mknod,
883 .rename = hostfs_rename,
884 .permission = hostfs_permission,
885 .setattr = hostfs_setattr,
886};
887
888static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd)
889{
890 char *link = __getname();
891 if (link) {
892 char *path = dentry_name(dentry);
893 int err = -ENOMEM;
894 if (path) {
895 err = hostfs_do_readlink(path, link, PATH_MAX);
896 if (err == PATH_MAX)
897 err = -E2BIG;
898 __putname(path);
899 }
900 if (err < 0) {
901 __putname(link);
902 link = ERR_PTR(err);
903 }
904 } else {
905 link = ERR_PTR(-ENOMEM);
906 }
907
908 nd_set_link(nd, link);
909 return NULL;
910}
911
912static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
913{
914 char *s = nd_get_link(nd);
915 if (!IS_ERR(s))
916 __putname(s);
917}
918
919static const struct inode_operations hostfs_link_iops = {
920 .readlink = generic_readlink,
921 .follow_link = hostfs_follow_link,
922 .put_link = hostfs_put_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 = &hostfs_dentry_ops;
936 sb->s_maxbytes = MAX_LFS_FILESIZE;
937
938 /* NULL is printed as <NULL> by sprintf: avoid that. */
939 if (req_root == NULL)
940 req_root = "";
941
942 err = -ENOMEM;
943 sb->s_fs_info = host_root_path =
944 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL);
945 if (host_root_path == NULL)
946 goto out;
947
948 sprintf(host_root_path, "%s/%s", root_ino, req_root);
949
950 root_inode = new_inode(sb);
951 if (!root_inode)
952 goto out;
953
954 err = read_name(root_inode, host_root_path);
955 if (err)
956 goto out_put;
957
958 if (S_ISLNK(root_inode->i_mode)) {
959 char *name = follow_link(host_root_path);
960 if (IS_ERR(name))
961 err = PTR_ERR(name);
962 else
963 err = read_name(root_inode, name);
964 kfree(name);
965 if (err)
966 goto out_put;
967 }
968
969 err = -ENOMEM;
970 sb->s_root = d_alloc_root(root_inode);
971 if (sb->s_root == NULL)
972 goto out_put;
973
974 return 0;
975
976out_put:
977 iput(root_inode);
978out:
979 return err;
980}
981
982static struct dentry *hostfs_read_sb(struct file_system_type *type,
983 int flags, const char *dev_name,
984 void *data)
985{
986 return mount_nodev(type, flags, data, hostfs_fill_sb_common);
987}
988
989static void hostfs_kill_sb(struct super_block *s)
990{
991 kill_anon_super(s);
992 kfree(s->s_fs_info);
993}
994
995static struct file_system_type hostfs_type = {
996 .owner = THIS_MODULE,
997 .name = "hostfs",
998 .mount = hostfs_read_sb,
999 .kill_sb = hostfs_kill_sb,
1000 .fs_flags = 0,
1001};
1002
1003static int __init init_hostfs(void)
1004{
1005 return register_filesystem(&hostfs_type);
1006}
1007
1008static void __exit exit_hostfs(void)
1009{
1010 unregister_filesystem(&hostfs_type);
1011}
1012
1013module_init(init_hostfs)
1014module_exit(exit_hostfs)
1015MODULE_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/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");