Version:  2.0.40 2.2.26 2.4.37 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16

Linux/fs/debugfs/inode.c

  1 /*
  2  *  inode.c - part of debugfs, a tiny little debug file system
  3  *
  4  *  Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
  5  *  Copyright (C) 2004 IBM Inc.
  6  *
  7  *      This program is free software; you can redistribute it and/or
  8  *      modify it under the terms of the GNU General Public License version
  9  *      2 as published by the Free Software Foundation.
 10  *
 11  *  debugfs is for people to use instead of /proc or /sys.
 12  *  See Documentation/DocBook/kernel-api for more details.
 13  *
 14  */
 15 
 16 #include <linux/module.h>
 17 #include <linux/fs.h>
 18 #include <linux/mount.h>
 19 #include <linux/pagemap.h>
 20 #include <linux/init.h>
 21 #include <linux/kobject.h>
 22 #include <linux/namei.h>
 23 #include <linux/debugfs.h>
 24 #include <linux/fsnotify.h>
 25 #include <linux/string.h>
 26 #include <linux/seq_file.h>
 27 #include <linux/parser.h>
 28 #include <linux/magic.h>
 29 #include <linux/slab.h>
 30 
 31 #define DEBUGFS_DEFAULT_MODE    0700
 32 
 33 static struct vfsmount *debugfs_mount;
 34 static int debugfs_mount_count;
 35 static bool debugfs_registered;
 36 
 37 static struct inode *debugfs_get_inode(struct super_block *sb, umode_t mode, dev_t dev,
 38                                        void *data, const struct file_operations *fops)
 39 
 40 {
 41         struct inode *inode = new_inode(sb);
 42 
 43         if (inode) {
 44                 inode->i_ino = get_next_ino();
 45                 inode->i_mode = mode;
 46                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 47                 switch (mode & S_IFMT) {
 48                 default:
 49                         init_special_inode(inode, mode, dev);
 50                         break;
 51                 case S_IFREG:
 52                         inode->i_fop = fops ? fops : &debugfs_file_operations;
 53                         inode->i_private = data;
 54                         break;
 55                 case S_IFLNK:
 56                         inode->i_op = &debugfs_link_operations;
 57                         inode->i_private = data;
 58                         break;
 59                 case S_IFDIR:
 60                         inode->i_op = &simple_dir_inode_operations;
 61                         inode->i_fop = &simple_dir_operations;
 62 
 63                         /* directory inodes start off with i_nlink == 2
 64                          * (for "." entry) */
 65                         inc_nlink(inode);
 66                         break;
 67                 }
 68         }
 69         return inode; 
 70 }
 71 
 72 /* SMP-safe */
 73 static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
 74                          umode_t mode, dev_t dev, void *data,
 75                          const struct file_operations *fops)
 76 {
 77         struct inode *inode;
 78         int error = -EPERM;
 79 
 80         if (dentry->d_inode)
 81                 return -EEXIST;
 82 
 83         inode = debugfs_get_inode(dir->i_sb, mode, dev, data, fops);
 84         if (inode) {
 85                 d_instantiate(dentry, inode);
 86                 dget(dentry);
 87                 error = 0;
 88         }
 89         return error;
 90 }
 91 
 92 static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 93 {
 94         int res;
 95 
 96         mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
 97         res = debugfs_mknod(dir, dentry, mode, 0, NULL, NULL);
 98         if (!res) {
 99                 inc_nlink(dir);
100                 fsnotify_mkdir(dir, dentry);
101         }
102         return res;
103 }
104 
105 static int debugfs_link(struct inode *dir, struct dentry *dentry, umode_t mode,
106                         void *data)
107 {
108         mode = (mode & S_IALLUGO) | S_IFLNK;
109         return debugfs_mknod(dir, dentry, mode, 0, data, NULL);
110 }
111 
112 static int debugfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
113                           void *data, const struct file_operations *fops)
114 {
115         int res;
116 
117         mode = (mode & S_IALLUGO) | S_IFREG;
118         res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
119         if (!res)
120                 fsnotify_create(dir, dentry);
121         return res;
122 }
123 
124 static inline int debugfs_positive(struct dentry *dentry)
125 {
126         return dentry->d_inode && !d_unhashed(dentry);
127 }
128 
129 struct debugfs_mount_opts {
130         kuid_t uid;
131         kgid_t gid;
132         umode_t mode;
133 };
134 
135 enum {
136         Opt_uid,
137         Opt_gid,
138         Opt_mode,
139         Opt_err
140 };
141 
142 static const match_table_t tokens = {
143         {Opt_uid, "uid=%u"},
144         {Opt_gid, "gid=%u"},
145         {Opt_mode, "mode=%o"},
146         {Opt_err, NULL}
147 };
148 
149 struct debugfs_fs_info {
150         struct debugfs_mount_opts mount_opts;
151 };
152 
153 static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
154 {
155         substring_t args[MAX_OPT_ARGS];
156         int option;
157         int token;
158         kuid_t uid;
159         kgid_t gid;
160         char *p;
161 
162         opts->mode = DEBUGFS_DEFAULT_MODE;
163 
164         while ((p = strsep(&data, ",")) != NULL) {
165                 if (!*p)
166                         continue;
167 
168                 token = match_token(p, tokens, args);
169                 switch (token) {
170                 case Opt_uid:
171                         if (match_int(&args[0], &option))
172                                 return -EINVAL;
173                         uid = make_kuid(current_user_ns(), option);
174                         if (!uid_valid(uid))
175                                 return -EINVAL;
176                         opts->uid = uid;
177                         break;
178                 case Opt_gid:
179                         if (match_int(&args[0], &option))
180                                 return -EINVAL;
181                         gid = make_kgid(current_user_ns(), option);
182                         if (!gid_valid(gid))
183                                 return -EINVAL;
184                         opts->gid = gid;
185                         break;
186                 case Opt_mode:
187                         if (match_octal(&args[0], &option))
188                                 return -EINVAL;
189                         opts->mode = option & S_IALLUGO;
190                         break;
191                 /*
192                  * We might like to report bad mount options here;
193                  * but traditionally debugfs has ignored all mount options
194                  */
195                 }
196         }
197 
198         return 0;
199 }
200 
201 static int debugfs_apply_options(struct super_block *sb)
202 {
203         struct debugfs_fs_info *fsi = sb->s_fs_info;
204         struct inode *inode = sb->s_root->d_inode;
205         struct debugfs_mount_opts *opts = &fsi->mount_opts;
206 
207         inode->i_mode &= ~S_IALLUGO;
208         inode->i_mode |= opts->mode;
209 
210         inode->i_uid = opts->uid;
211         inode->i_gid = opts->gid;
212 
213         return 0;
214 }
215 
216 static int debugfs_remount(struct super_block *sb, int *flags, char *data)
217 {
218         int err;
219         struct debugfs_fs_info *fsi = sb->s_fs_info;
220 
221         sync_filesystem(sb);
222         err = debugfs_parse_options(data, &fsi->mount_opts);
223         if (err)
224                 goto fail;
225 
226         debugfs_apply_options(sb);
227 
228 fail:
229         return err;
230 }
231 
232 static int debugfs_show_options(struct seq_file *m, struct dentry *root)
233 {
234         struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
235         struct debugfs_mount_opts *opts = &fsi->mount_opts;
236 
237         if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
238                 seq_printf(m, ",uid=%u",
239                            from_kuid_munged(&init_user_ns, opts->uid));
240         if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
241                 seq_printf(m, ",gid=%u",
242                            from_kgid_munged(&init_user_ns, opts->gid));
243         if (opts->mode != DEBUGFS_DEFAULT_MODE)
244                 seq_printf(m, ",mode=%o", opts->mode);
245 
246         return 0;
247 }
248 
249 static const struct super_operations debugfs_super_operations = {
250         .statfs         = simple_statfs,
251         .remount_fs     = debugfs_remount,
252         .show_options   = debugfs_show_options,
253 };
254 
255 static int debug_fill_super(struct super_block *sb, void *data, int silent)
256 {
257         static struct tree_descr debug_files[] = {{""}};
258         struct debugfs_fs_info *fsi;
259         int err;
260 
261         save_mount_options(sb, data);
262 
263         fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
264         sb->s_fs_info = fsi;
265         if (!fsi) {
266                 err = -ENOMEM;
267                 goto fail;
268         }
269 
270         err = debugfs_parse_options(data, &fsi->mount_opts);
271         if (err)
272                 goto fail;
273 
274         err  =  simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
275         if (err)
276                 goto fail;
277 
278         sb->s_op = &debugfs_super_operations;
279 
280         debugfs_apply_options(sb);
281 
282         return 0;
283 
284 fail:
285         kfree(fsi);
286         sb->s_fs_info = NULL;
287         return err;
288 }
289 
290 static struct dentry *debug_mount(struct file_system_type *fs_type,
291                         int flags, const char *dev_name,
292                         void *data)
293 {
294         return mount_single(fs_type, flags, data, debug_fill_super);
295 }
296 
297 static struct file_system_type debug_fs_type = {
298         .owner =        THIS_MODULE,
299         .name =         "debugfs",
300         .mount =        debug_mount,
301         .kill_sb =      kill_litter_super,
302 };
303 MODULE_ALIAS_FS("debugfs");
304 
305 static struct dentry *__create_file(const char *name, umode_t mode,
306                                     struct dentry *parent, void *data,
307                                     const struct file_operations *fops)
308 {
309         struct dentry *dentry = NULL;
310         int error;
311 
312         pr_debug("debugfs: creating file '%s'\n",name);
313 
314         error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
315                               &debugfs_mount_count);
316         if (error)
317                 goto exit;
318 
319         /* If the parent is not specified, we create it in the root.
320          * We need the root dentry to do this, which is in the super 
321          * block. A pointer to that is in the struct vfsmount that we
322          * have around.
323          */
324         if (!parent)
325                 parent = debugfs_mount->mnt_root;
326 
327         mutex_lock(&parent->d_inode->i_mutex);
328         dentry = lookup_one_len(name, parent, strlen(name));
329         if (!IS_ERR(dentry)) {
330                 switch (mode & S_IFMT) {
331                 case S_IFDIR:
332                         error = debugfs_mkdir(parent->d_inode, dentry, mode);
333                                               
334                         break;
335                 case S_IFLNK:
336                         error = debugfs_link(parent->d_inode, dentry, mode,
337                                              data);
338                         break;
339                 default:
340                         error = debugfs_create(parent->d_inode, dentry, mode,
341                                                data, fops);
342                         break;
343                 }
344                 dput(dentry);
345         } else
346                 error = PTR_ERR(dentry);
347         mutex_unlock(&parent->d_inode->i_mutex);
348 
349         if (error) {
350                 dentry = NULL;
351                 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
352         }
353 exit:
354         return dentry;
355 }
356 
357 /**
358  * debugfs_create_file - create a file in the debugfs filesystem
359  * @name: a pointer to a string containing the name of the file to create.
360  * @mode: the permission that the file should have.
361  * @parent: a pointer to the parent dentry for this file.  This should be a
362  *          directory dentry if set.  If this parameter is NULL, then the
363  *          file will be created in the root of the debugfs filesystem.
364  * @data: a pointer to something that the caller will want to get to later
365  *        on.  The inode.i_private pointer will point to this value on
366  *        the open() call.
367  * @fops: a pointer to a struct file_operations that should be used for
368  *        this file.
369  *
370  * This is the basic "create a file" function for debugfs.  It allows for a
371  * wide range of flexibility in creating a file, or a directory (if you want
372  * to create a directory, the debugfs_create_dir() function is
373  * recommended to be used instead.)
374  *
375  * This function will return a pointer to a dentry if it succeeds.  This
376  * pointer must be passed to the debugfs_remove() function when the file is
377  * to be removed (no automatic cleanup happens if your module is unloaded,
378  * you are responsible here.)  If an error occurs, %NULL will be returned.
379  *
380  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
381  * returned.
382  */
383 struct dentry *debugfs_create_file(const char *name, umode_t mode,
384                                    struct dentry *parent, void *data,
385                                    const struct file_operations *fops)
386 {
387         switch (mode & S_IFMT) {
388         case S_IFREG:
389         case 0:
390                 break;
391         default:
392                 BUG();
393         }
394 
395         return __create_file(name, mode, parent, data, fops);
396 }
397 EXPORT_SYMBOL_GPL(debugfs_create_file);
398 
399 /**
400  * debugfs_create_dir - create a directory in the debugfs filesystem
401  * @name: a pointer to a string containing the name of the directory to
402  *        create.
403  * @parent: a pointer to the parent dentry for this file.  This should be a
404  *          directory dentry if set.  If this parameter is NULL, then the
405  *          directory will be created in the root of the debugfs filesystem.
406  *
407  * This function creates a directory in debugfs with the given name.
408  *
409  * This function will return a pointer to a dentry if it succeeds.  This
410  * pointer must be passed to the debugfs_remove() function when the file is
411  * to be removed (no automatic cleanup happens if your module is unloaded,
412  * you are responsible here.)  If an error occurs, %NULL will be returned.
413  *
414  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
415  * returned.
416  */
417 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
418 {
419         return __create_file(name, S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
420                                    parent, NULL, NULL);
421 }
422 EXPORT_SYMBOL_GPL(debugfs_create_dir);
423 
424 /**
425  * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
426  * @name: a pointer to a string containing the name of the symbolic link to
427  *        create.
428  * @parent: a pointer to the parent dentry for this symbolic link.  This
429  *          should be a directory dentry if set.  If this parameter is NULL,
430  *          then the symbolic link will be created in the root of the debugfs
431  *          filesystem.
432  * @target: a pointer to a string containing the path to the target of the
433  *          symbolic link.
434  *
435  * This function creates a symbolic link with the given name in debugfs that
436  * links to the given target path.
437  *
438  * This function will return a pointer to a dentry if it succeeds.  This
439  * pointer must be passed to the debugfs_remove() function when the symbolic
440  * link is to be removed (no automatic cleanup happens if your module is
441  * unloaded, you are responsible here.)  If an error occurs, %NULL will be
442  * returned.
443  *
444  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
445  * returned.
446  */
447 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
448                                       const char *target)
449 {
450         struct dentry *result;
451         char *link;
452 
453         link = kstrdup(target, GFP_KERNEL);
454         if (!link)
455                 return NULL;
456 
457         result = __create_file(name, S_IFLNK | S_IRWXUGO, parent, link, NULL);
458         if (!result)
459                 kfree(link);
460         return result;
461 }
462 EXPORT_SYMBOL_GPL(debugfs_create_symlink);
463 
464 static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
465 {
466         int ret = 0;
467 
468         if (debugfs_positive(dentry)) {
469                 if (dentry->d_inode) {
470                         dget(dentry);
471                         switch (dentry->d_inode->i_mode & S_IFMT) {
472                         case S_IFDIR:
473                                 ret = simple_rmdir(parent->d_inode, dentry);
474                                 break;
475                         case S_IFLNK:
476                                 kfree(dentry->d_inode->i_private);
477                                 /* fall through */
478                         default:
479                                 simple_unlink(parent->d_inode, dentry);
480                                 break;
481                         }
482                         if (!ret)
483                                 d_delete(dentry);
484                         dput(dentry);
485                 }
486         }
487         return ret;
488 }
489 
490 /**
491  * debugfs_remove - removes a file or directory from the debugfs filesystem
492  * @dentry: a pointer to a the dentry of the file or directory to be
493  *          removed.
494  *
495  * This function removes a file or directory in debugfs that was previously
496  * created with a call to another debugfs function (like
497  * debugfs_create_file() or variants thereof.)
498  *
499  * This function is required to be called in order for the file to be
500  * removed, no automatic cleanup of files will happen when a module is
501  * removed, you are responsible here.
502  */
503 void debugfs_remove(struct dentry *dentry)
504 {
505         struct dentry *parent;
506         int ret;
507 
508         if (IS_ERR_OR_NULL(dentry))
509                 return;
510 
511         parent = dentry->d_parent;
512         if (!parent || !parent->d_inode)
513                 return;
514 
515         mutex_lock(&parent->d_inode->i_mutex);
516         ret = __debugfs_remove(dentry, parent);
517         mutex_unlock(&parent->d_inode->i_mutex);
518         if (!ret)
519                 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
520 }
521 EXPORT_SYMBOL_GPL(debugfs_remove);
522 
523 /**
524  * debugfs_remove_recursive - recursively removes a directory
525  * @dentry: a pointer to a the dentry of the directory to be removed.
526  *
527  * This function recursively removes a directory tree in debugfs that
528  * was previously created with a call to another debugfs function
529  * (like debugfs_create_file() or variants thereof.)
530  *
531  * This function is required to be called in order for the file to be
532  * removed, no automatic cleanup of files will happen when a module is
533  * removed, you are responsible here.
534  */
535 void debugfs_remove_recursive(struct dentry *dentry)
536 {
537         struct dentry *child, *next, *parent;
538 
539         if (IS_ERR_OR_NULL(dentry))
540                 return;
541 
542         parent = dentry->d_parent;
543         if (!parent || !parent->d_inode)
544                 return;
545 
546         parent = dentry;
547  down:
548         mutex_lock(&parent->d_inode->i_mutex);
549         list_for_each_entry_safe(child, next, &parent->d_subdirs, d_u.d_child) {
550                 if (!debugfs_positive(child))
551                         continue;
552 
553                 /* perhaps simple_empty(child) makes more sense */
554                 if (!list_empty(&child->d_subdirs)) {
555                         mutex_unlock(&parent->d_inode->i_mutex);
556                         parent = child;
557                         goto down;
558                 }
559  up:
560                 if (!__debugfs_remove(child, parent))
561                         simple_release_fs(&debugfs_mount, &debugfs_mount_count);
562         }
563 
564         mutex_unlock(&parent->d_inode->i_mutex);
565         child = parent;
566         parent = parent->d_parent;
567         mutex_lock(&parent->d_inode->i_mutex);
568 
569         if (child != dentry) {
570                 next = list_next_entry(child, d_u.d_child);
571                 goto up;
572         }
573 
574         if (!__debugfs_remove(child, parent))
575                 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
576         mutex_unlock(&parent->d_inode->i_mutex);
577 }
578 EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
579 
580 /**
581  * debugfs_rename - rename a file/directory in the debugfs filesystem
582  * @old_dir: a pointer to the parent dentry for the renamed object. This
583  *          should be a directory dentry.
584  * @old_dentry: dentry of an object to be renamed.
585  * @new_dir: a pointer to the parent dentry where the object should be
586  *          moved. This should be a directory dentry.
587  * @new_name: a pointer to a string containing the target name.
588  *
589  * This function renames a file/directory in debugfs.  The target must not
590  * exist for rename to succeed.
591  *
592  * This function will return a pointer to old_dentry (which is updated to
593  * reflect renaming) if it succeeds. If an error occurs, %NULL will be
594  * returned.
595  *
596  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
597  * returned.
598  */
599 struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
600                 struct dentry *new_dir, const char *new_name)
601 {
602         int error;
603         struct dentry *dentry = NULL, *trap;
604         const char *old_name;
605 
606         trap = lock_rename(new_dir, old_dir);
607         /* Source or destination directories don't exist? */
608         if (!old_dir->d_inode || !new_dir->d_inode)
609                 goto exit;
610         /* Source does not exist, cyclic rename, or mountpoint? */
611         if (!old_dentry->d_inode || old_dentry == trap ||
612             d_mountpoint(old_dentry))
613                 goto exit;
614         dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
615         /* Lookup failed, cyclic rename or target exists? */
616         if (IS_ERR(dentry) || dentry == trap || dentry->d_inode)
617                 goto exit;
618 
619         old_name = fsnotify_oldname_init(old_dentry->d_name.name);
620 
621         error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode,
622                 dentry);
623         if (error) {
624                 fsnotify_oldname_free(old_name);
625                 goto exit;
626         }
627         d_move(old_dentry, dentry);
628         fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name,
629                 S_ISDIR(old_dentry->d_inode->i_mode),
630                 NULL, old_dentry);
631         fsnotify_oldname_free(old_name);
632         unlock_rename(new_dir, old_dir);
633         dput(dentry);
634         return old_dentry;
635 exit:
636         if (dentry && !IS_ERR(dentry))
637                 dput(dentry);
638         unlock_rename(new_dir, old_dir);
639         return NULL;
640 }
641 EXPORT_SYMBOL_GPL(debugfs_rename);
642 
643 /**
644  * debugfs_initialized - Tells whether debugfs has been registered
645  */
646 bool debugfs_initialized(void)
647 {
648         return debugfs_registered;
649 }
650 EXPORT_SYMBOL_GPL(debugfs_initialized);
651 
652 
653 static struct kobject *debug_kobj;
654 
655 static int __init debugfs_init(void)
656 {
657         int retval;
658 
659         debug_kobj = kobject_create_and_add("debug", kernel_kobj);
660         if (!debug_kobj)
661                 return -EINVAL;
662 
663         retval = register_filesystem(&debug_fs_type);
664         if (retval)
665                 kobject_put(debug_kobj);
666         else
667                 debugfs_registered = true;
668 
669         return retval;
670 }
671 core_initcall(debugfs_init);
672 
673 

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