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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/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");
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};
30
31static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
32{
33 return list_entry(inode, struct hostfs_inode_info, vfs_inode);
34}
35
36#define FILE_HOSTFS_I(file) HOSTFS_I(file_inode(file))
37
38static struct kmem_cache *hostfs_inode_cache;
39
40/* Changed in hostfs_args before the kernel starts running */
41static char *root_ino = "";
42static int append = 0;
43
44static const struct inode_operations hostfs_iops;
45static const struct inode_operations hostfs_dir_iops;
46static const struct inode_operations hostfs_link_iops;
47
48#ifndef MODULE
49static int __init hostfs_args(char *options, int *add)
50{
51 char *ptr;
52
53 ptr = strchr(options, ',');
54 if (ptr != NULL)
55 *ptr++ = '\0';
56 if (*options != '\0')
57 root_ino = options;
58
59 options = ptr;
60 while (options) {
61 ptr = strchr(options, ',');
62 if (ptr != NULL)
63 *ptr++ = '\0';
64 if (*options != '\0') {
65 if (!strcmp(options, "append"))
66 append = 1;
67 else printf("hostfs_args - unsupported option - %s\n",
68 options);
69 }
70 options = ptr;
71 }
72 return 0;
73}
74
75__uml_setup("hostfs=", hostfs_args,
76"hostfs=<root dir>,<flags>,...\n"
77" This is used to set hostfs parameters. The root directory argument\n"
78" is used to confine all hostfs mounts to within the specified directory\n"
79" tree on the host. If this isn't specified, then a user inside UML can\n"
80" mount anything on the host that's accessible to the user that's running\n"
81" it.\n"
82" The only flag currently supported is 'append', which specifies that all\n"
83" files opened by hostfs will be opened in append mode.\n\n"
84);
85#endif
86
87static char *__dentry_name(struct dentry *dentry, char *name)
88{
89 char *p = dentry_path_raw(dentry, name, PATH_MAX);
90 char *root;
91 size_t len;
92
93 root = dentry->d_sb->s_fs_info;
94 len = strlen(root);
95 if (IS_ERR(p)) {
96 __putname(name);
97 return NULL;
98 }
99
100 /*
101 * This function relies on the fact that dentry_path_raw() will place
102 * the path name at the end of the provided buffer.
103 */
104 BUG_ON(p + strlen(p) + 1 != name + PATH_MAX);
105
106 strscpy(name, root, PATH_MAX);
107 if (len > p - name) {
108 __putname(name);
109 return NULL;
110 }
111
112 if (p > name + len)
113 strcpy(name + len, p);
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);
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 char *name, *resolved, *end;
146 int n;
147
148 name = kmalloc(PATH_MAX, GFP_KERNEL);
149 if (!name) {
150 n = -ENOMEM;
151 goto out_free;
152 }
153
154 n = hostfs_do_readlink(link, name, PATH_MAX);
155 if (n < 0)
156 goto out_free;
157 else if (n == PATH_MAX) {
158 n = -E2BIG;
159 goto out_free;
160 }
161
162 if (*name == '/')
163 return name;
164
165 end = strrchr(link, '/');
166 if (end == NULL)
167 return name;
168
169 *(end + 1) = '\0';
170
171 resolved = kasprintf(GFP_KERNEL, "%s%s", link, name);
172 if (resolved == NULL) {
173 n = -ENOMEM;
174 goto out_free;
175 }
176
177 kfree(name);
178 return resolved;
179
180 out_free:
181 kfree(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 = alloc_inode_sb(sb, hostfs_inode_cache, 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 kmem_cache_free(hostfs_inode_cache, 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_dentry(file));
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 .splice_write = iter_file_splice_write,
386 .read_iter = generic_file_read_iter,
387 .write_iter = generic_file_write_iter,
388 .mmap = generic_file_mmap,
389 .open = hostfs_open,
390 .release = hostfs_file_release,
391 .fsync = hostfs_fsync,
392};
393
394static const struct file_operations hostfs_dir_fops = {
395 .llseek = generic_file_llseek,
396 .iterate_shared = hostfs_readdir,
397 .read = generic_read_dir,
398 .open = hostfs_open,
399 .fsync = hostfs_fsync,
400};
401
402static int hostfs_writepage(struct page *page, struct writeback_control *wbc)
403{
404 struct address_space *mapping = page->mapping;
405 struct inode *inode = mapping->host;
406 char *buffer;
407 loff_t base = page_offset(page);
408 int count = PAGE_SIZE;
409 int end_index = inode->i_size >> PAGE_SHIFT;
410 int err;
411
412 if (page->index >= end_index)
413 count = inode->i_size & (PAGE_SIZE-1);
414
415 buffer = kmap(page);
416
417 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
418 if (err != count) {
419 if (err >= 0)
420 err = -EIO;
421 mapping_set_error(mapping, err);
422 goto out;
423 }
424
425 if (base > inode->i_size)
426 inode->i_size = base;
427
428 err = 0;
429
430 out:
431 kunmap(page);
432
433 unlock_page(page);
434 return err;
435}
436
437static int hostfs_read_folio(struct file *file, struct folio *folio)
438{
439 struct page *page = &folio->page;
440 char *buffer;
441 loff_t start = page_offset(page);
442 int bytes_read, ret = 0;
443
444 buffer = kmap(page);
445 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
446 PAGE_SIZE);
447 if (bytes_read < 0) {
448 ClearPageUptodate(page);
449 SetPageError(page);
450 ret = bytes_read;
451 goto out;
452 }
453
454 memset(buffer + bytes_read, 0, PAGE_SIZE - bytes_read);
455
456 ClearPageError(page);
457 SetPageUptodate(page);
458
459 out:
460 flush_dcache_page(page);
461 kunmap(page);
462 unlock_page(page);
463 return ret;
464}
465
466static int hostfs_write_begin(struct file *file, struct address_space *mapping,
467 loff_t pos, unsigned len,
468 struct page **pagep, void **fsdata)
469{
470 pgoff_t index = pos >> PAGE_SHIFT;
471
472 *pagep = grab_cache_page_write_begin(mapping, index);
473 if (!*pagep)
474 return -ENOMEM;
475 return 0;
476}
477
478static int hostfs_write_end(struct file *file, struct address_space *mapping,
479 loff_t pos, unsigned len, unsigned copied,
480 struct page *page, void *fsdata)
481{
482 struct inode *inode = mapping->host;
483 void *buffer;
484 unsigned from = pos & (PAGE_SIZE - 1);
485 int err;
486
487 buffer = kmap(page);
488 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
489 kunmap(page);
490
491 if (!PageUptodate(page) && err == PAGE_SIZE)
492 SetPageUptodate(page);
493
494 /*
495 * If err > 0, write_file has added err to pos, so we are comparing
496 * i_size against the last byte written.
497 */
498 if (err > 0 && (pos > inode->i_size))
499 inode->i_size = pos;
500 unlock_page(page);
501 put_page(page);
502
503 return err;
504}
505
506static const struct address_space_operations hostfs_aops = {
507 .writepage = hostfs_writepage,
508 .read_folio = hostfs_read_folio,
509 .dirty_folio = filemap_dirty_folio,
510 .write_begin = hostfs_write_begin,
511 .write_end = hostfs_write_end,
512};
513
514static int read_name(struct inode *ino, char *name)
515{
516 dev_t rdev;
517 struct hostfs_stat st;
518 int err = stat_file(name, &st, -1);
519 if (err)
520 return err;
521
522 /* Reencode maj and min with the kernel encoding.*/
523 rdev = MKDEV(st.maj, st.min);
524
525 switch (st.mode & S_IFMT) {
526 case S_IFLNK:
527 ino->i_op = &hostfs_link_iops;
528 break;
529 case S_IFDIR:
530 ino->i_op = &hostfs_dir_iops;
531 ino->i_fop = &hostfs_dir_fops;
532 break;
533 case S_IFCHR:
534 case S_IFBLK:
535 case S_IFIFO:
536 case S_IFSOCK:
537 init_special_inode(ino, st.mode & S_IFMT, rdev);
538 ino->i_op = &hostfs_iops;
539 break;
540 case S_IFREG:
541 ino->i_op = &hostfs_iops;
542 ino->i_fop = &hostfs_file_fops;
543 ino->i_mapping->a_ops = &hostfs_aops;
544 break;
545 default:
546 return -EIO;
547 }
548
549 ino->i_ino = st.ino;
550 ino->i_mode = st.mode;
551 set_nlink(ino, st.nlink);
552 i_uid_write(ino, st.uid);
553 i_gid_write(ino, st.gid);
554 ino->i_atime = (struct timespec64){ st.atime.tv_sec, st.atime.tv_nsec };
555 ino->i_mtime = (struct timespec64){ st.mtime.tv_sec, st.mtime.tv_nsec };
556 ino->i_ctime = (struct timespec64){ st.ctime.tv_sec, st.ctime.tv_nsec };
557 ino->i_size = st.size;
558 ino->i_blocks = st.blocks;
559 return 0;
560}
561
562static int hostfs_create(struct user_namespace *mnt_userns, struct inode *dir,
563 struct dentry *dentry, umode_t mode, bool excl)
564{
565 struct inode *inode;
566 char *name;
567 int error, fd;
568
569 inode = hostfs_iget(dir->i_sb);
570 if (IS_ERR(inode)) {
571 error = PTR_ERR(inode);
572 goto out;
573 }
574
575 error = -ENOMEM;
576 name = dentry_name(dentry);
577 if (name == NULL)
578 goto out_put;
579
580 fd = file_create(name, mode & 0777);
581 if (fd < 0)
582 error = fd;
583 else
584 error = read_name(inode, name);
585
586 __putname(name);
587 if (error)
588 goto out_put;
589
590 HOSTFS_I(inode)->fd = fd;
591 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
592 d_instantiate(dentry, inode);
593 return 0;
594
595 out_put:
596 iput(inode);
597 out:
598 return error;
599}
600
601static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
602 unsigned int flags)
603{
604 struct inode *inode;
605 char *name;
606 int err;
607
608 inode = hostfs_iget(ino->i_sb);
609 if (IS_ERR(inode))
610 goto out;
611
612 err = -ENOMEM;
613 name = dentry_name(dentry);
614 if (name) {
615 err = read_name(inode, name);
616 __putname(name);
617 }
618 if (err) {
619 iput(inode);
620 inode = (err == -ENOENT) ? NULL : ERR_PTR(err);
621 }
622 out:
623 return d_splice_alias(inode, dentry);
624}
625
626static int hostfs_link(struct dentry *to, struct inode *ino,
627 struct dentry *from)
628{
629 char *from_name, *to_name;
630 int err;
631
632 if ((from_name = dentry_name(from)) == NULL)
633 return -ENOMEM;
634 to_name = dentry_name(to);
635 if (to_name == NULL) {
636 __putname(from_name);
637 return -ENOMEM;
638 }
639 err = link_file(to_name, from_name);
640 __putname(from_name);
641 __putname(to_name);
642 return err;
643}
644
645static int hostfs_unlink(struct inode *ino, struct dentry *dentry)
646{
647 char *file;
648 int err;
649
650 if (append)
651 return -EPERM;
652
653 if ((file = dentry_name(dentry)) == NULL)
654 return -ENOMEM;
655
656 err = unlink_file(file);
657 __putname(file);
658 return err;
659}
660
661static int hostfs_symlink(struct user_namespace *mnt_userns, struct inode *ino,
662 struct dentry *dentry, const char *to)
663{
664 char *file;
665 int err;
666
667 if ((file = dentry_name(dentry)) == NULL)
668 return -ENOMEM;
669 err = make_symlink(file, to);
670 __putname(file);
671 return err;
672}
673
674static int hostfs_mkdir(struct user_namespace *mnt_userns, struct inode *ino,
675 struct dentry *dentry, umode_t mode)
676{
677 char *file;
678 int err;
679
680 if ((file = dentry_name(dentry)) == NULL)
681 return -ENOMEM;
682 err = do_mkdir(file, mode);
683 __putname(file);
684 return err;
685}
686
687static int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
688{
689 char *file;
690 int err;
691
692 if ((file = dentry_name(dentry)) == NULL)
693 return -ENOMEM;
694 err = hostfs_do_rmdir(file);
695 __putname(file);
696 return err;
697}
698
699static int hostfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
700 struct dentry *dentry, umode_t mode, dev_t dev)
701{
702 struct inode *inode;
703 char *name;
704 int err;
705
706 inode = hostfs_iget(dir->i_sb);
707 if (IS_ERR(inode)) {
708 err = PTR_ERR(inode);
709 goto out;
710 }
711
712 err = -ENOMEM;
713 name = dentry_name(dentry);
714 if (name == NULL)
715 goto out_put;
716
717 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
718 if (err)
719 goto out_free;
720
721 err = read_name(inode, name);
722 __putname(name);
723 if (err)
724 goto out_put;
725
726 d_instantiate(dentry, inode);
727 return 0;
728
729 out_free:
730 __putname(name);
731 out_put:
732 iput(inode);
733 out:
734 return err;
735}
736
737static int hostfs_rename2(struct user_namespace *mnt_userns,
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 user_namespace *mnt_userns,
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(&init_user_ns, ino, desired);
790 return err;
791}
792
793static int hostfs_setattr(struct user_namespace *mnt_userns,
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(&init_user_ns, 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(&init_user_ns, 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_sb_common(struct super_block *sb, void *d, int silent)
918{
919 struct inode *root_inode;
920 char *host_root_path, *req_root = d;
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 goto out;
932
933 /* NULL is printed as '(null)' by printf(): avoid that. */
934 if (req_root == NULL)
935 req_root = "";
936
937 err = -ENOMEM;
938 sb->s_fs_info = host_root_path =
939 kasprintf(GFP_KERNEL, "%s/%s", root_ino, req_root);
940 if (host_root_path == NULL)
941 goto out;
942
943 root_inode = new_inode(sb);
944 if (!root_inode)
945 goto out;
946
947 err = read_name(root_inode, host_root_path);
948 if (err)
949 goto out_put;
950
951 if (S_ISLNK(root_inode->i_mode)) {
952 char *name = follow_link(host_root_path);
953 if (IS_ERR(name)) {
954 err = PTR_ERR(name);
955 goto out_put;
956 }
957 err = read_name(root_inode, name);
958 kfree(name);
959 if (err)
960 goto out_put;
961 }
962
963 err = -ENOMEM;
964 sb->s_root = d_make_root(root_inode);
965 if (sb->s_root == NULL)
966 goto out;
967
968 return 0;
969
970out_put:
971 iput(root_inode);
972out:
973 return err;
974}
975
976static struct dentry *hostfs_read_sb(struct file_system_type *type,
977 int flags, const char *dev_name,
978 void *data)
979{
980 return mount_nodev(type, flags, data, hostfs_fill_sb_common);
981}
982
983static void hostfs_kill_sb(struct super_block *s)
984{
985 kill_anon_super(s);
986 kfree(s->s_fs_info);
987}
988
989static struct file_system_type hostfs_type = {
990 .owner = THIS_MODULE,
991 .name = "hostfs",
992 .mount = hostfs_read_sb,
993 .kill_sb = hostfs_kill_sb,
994 .fs_flags = 0,
995};
996MODULE_ALIAS_FS("hostfs");
997
998static int __init init_hostfs(void)
999{
1000 hostfs_inode_cache = KMEM_CACHE(hostfs_inode_info, 0);
1001 if (!hostfs_inode_cache)
1002 return -ENOMEM;
1003 return register_filesystem(&hostfs_type);
1004}
1005
1006static void __exit exit_hostfs(void)
1007{
1008 unregister_filesystem(&hostfs_type);
1009 kmem_cache_destroy(hostfs_inode_cache);
1010}
1011
1012module_init(init_hostfs)
1013module_exit(exit_hostfs)
1014MODULE_LICENSE("GPL");