~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/fs/hostfs/hostfs_kern.c

Version: ~ [ linux-5.14-rc1 ] ~ [ linux-5.13.1 ] ~ [ linux-5.12.16 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.49 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.131 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.197 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.239 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.275 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.275 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

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

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp