/* *  inode.c - part of debugfs, a tiny little debug file system * *  Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com> *  Copyright (C) 2004 IBM Inc. * *	This program is free software; you can redistribute it and/or *	modify it under the terms of the GNU General Public License version *	2 as published by the Free Software Foundation. * *  debugfs is for people to use instead of /proc or /sys. *  See Documentation/DocBook/kernel-api for more details. * */ #include <linux/module.h>#include <linux/fs.h>#include <linux/mount.h>#include <linux/pagemap.h>#include <linux/init.h>#include <linux/kobject.h>#include <linux/namei.h>#include <linux/debugfs.h>#include <linux/fsnotify.h>#include <linux/string.h>#include <linux/seq_file.h>#include <linux/parser.h>#include <linux/magic.h>#include <linux/slab.h> #define DEBUGFS_DEFAULT_MODE	0700 static struct vfsmount *debugfs_mount;static int debugfs_mount_count;static bool debugfs_registered; static struct inode *debugfs_get_inode(struct super_block *sb, umode_t mode, dev_t dev,				       void *data, const struct file_operations *fops) {	struct inode *inode = new_inode(sb); 	if (inode) {		inode->i_ino = get_next_ino();		inode->i_mode = mode;		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;		switch (mode & S_IFMT) {		default:			init_special_inode(inode, mode, dev);			break;		case S_IFREG:			inode->i_fop = fops ? fops : &debugfs_file_operations;			inode->i_private = data;			break;		case S_IFLNK:			inode->i_op = &debugfs_link_operations;			inode->i_private = data;			break;		case S_IFDIR:			inode->i_op = &simple_dir_inode_operations;			inode->i_fop = &simple_dir_operations;			inode->i_private = NULL; 			/* directory inodes start off with i_nlink == 2			 * (for "." entry) */			inc_nlink(inode);			break;		}	}	return inode; } /* SMP-safe */static int debugfs_mknod(struct inode *dir, struct dentry *dentry,			 umode_t mode, dev_t dev, void *data,			 const struct file_operations *fops){	struct inode *inode;	int error = -EPERM; 	if (dentry->d_inode)		return -EEXIST; 	inode = debugfs_get_inode(dir->i_sb, mode, dev, data, fops);	if (inode) {		d_instantiate(dentry, inode);		dget(dentry);		error = 0;	}	return error;} static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode){	int res; 	mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;	res = debugfs_mknod(dir, dentry, mode, 0, NULL, NULL);	if (!res) {		inc_nlink(dir);		fsnotify_mkdir(dir, dentry);	}	return res;} static int debugfs_link(struct inode *dir, struct dentry *dentry, umode_t mode,			void *data){	mode = (mode & S_IALLUGO) | S_IFLNK;	return debugfs_mknod(dir, dentry, mode, 0, data, NULL);} static int debugfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,			  void *data, const struct file_operations *fops){	int res; 	mode = (mode & S_IALLUGO) | S_IFREG;	res = debugfs_mknod(dir, dentry, mode, 0, data, fops);	if (!res)		fsnotify_create(dir, dentry);	return res;} static inline int debugfs_positive(struct dentry *dentry){	return dentry->d_inode && !d_unhashed(dentry);} struct debugfs_mount_opts {	kuid_t uid;	kgid_t gid;	umode_t mode;}; enum {	Opt_uid,	Opt_gid,	Opt_mode,	Opt_err}; static const match_table_t tokens = {	{Opt_uid, "uid=%u"},	{Opt_gid, "gid=%u"},	{Opt_mode, "mode=%o"},	{Opt_err, NULL}}; struct debugfs_fs_info {	struct debugfs_mount_opts mount_opts;}; static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts){	substring_t args[MAX_OPT_ARGS];	int option;	int token;	kuid_t uid;	kgid_t gid;	char *p; 	opts->mode = DEBUGFS_DEFAULT_MODE; 	while ((p = strsep(&data, ",")) != NULL) {		if (!*p)			continue; 		token = match_token(p, tokens, args);		switch (token) {		case Opt_uid:			if (match_int(&args[0], &option))				return -EINVAL;			uid = make_kuid(current_user_ns(), option);			if (!uid_valid(uid))				return -EINVAL;			opts->uid = uid;			break;		case Opt_gid:			if (match_octal(&args[0], &option))				return -EINVAL;			gid = make_kgid(current_user_ns(), option);			if (!gid_valid(gid))				return -EINVAL;			opts->gid = gid;			break;		case Opt_mode:			if (match_octal(&args[0], &option))				return -EINVAL;			opts->mode = option & S_IALLUGO;			break;		/*		 * We might like to report bad mount options here;		 * but traditionally debugfs has ignored all mount options		 */		}	} 	return 0;} static int debugfs_apply_options(struct super_block *sb){	struct debugfs_fs_info *fsi = sb->s_fs_info;	struct inode *inode = sb->s_root->d_inode;	struct debugfs_mount_opts *opts = &fsi->mount_opts; 	inode->i_mode &= ~S_IALLUGO;	inode->i_mode |= opts->mode; 	inode->i_uid = opts->uid;	inode->i_gid = opts->gid; 	return 0;} static int debugfs_remount(struct super_block *sb, int *flags, char *data){	int err;	struct debugfs_fs_info *fsi = sb->s_fs_info; 	err = debugfs_parse_options(data, &fsi->mount_opts);	if (err)		goto fail; 	debugfs_apply_options(sb); fail:	return err;} static int debugfs_show_options(struct seq_file *m, struct dentry *root){	struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;	struct debugfs_mount_opts *opts = &fsi->mount_opts; 	if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))		seq_printf(m, ",uid=%u",			   from_kuid_munged(&init_user_ns, opts->uid));	if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))		seq_printf(m, ",gid=%u",			   from_kgid_munged(&init_user_ns, opts->gid));	if (opts->mode != DEBUGFS_DEFAULT_MODE)		seq_printf(m, ",mode=%o", opts->mode); 	return 0;} static const struct super_operations debugfs_super_operations = {	.statfs		= simple_statfs,	.remount_fs	= debugfs_remount,	.show_options	= debugfs_show_options,}; static int debug_fill_super(struct super_block *sb, void *data, int silent){	static struct tree_descr debug_files[] = {{""}};	struct debugfs_fs_info *fsi;	int err; 	save_mount_options(sb, data); 	fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);	sb->s_fs_info = fsi;	if (!fsi) {		err = -ENOMEM;		goto fail;	} 	err = debugfs_parse_options(data, &fsi->mount_opts);	if (err)		goto fail; 	err  =  simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);	if (err)		goto fail; 	sb->s_op = &debugfs_super_operations; 	debugfs_apply_options(sb); 	return 0; fail:	kfree(fsi);	sb->s_fs_info = NULL;	return err;} static struct dentry *debug_mount(struct file_system_type *fs_type,			int flags, const char *dev_name,			void *data){	return mount_single(fs_type, flags, data, debug_fill_super);} static struct file_system_type debug_fs_type = {	.owner =	THIS_MODULE,	.name =		"debugfs",	.mount =	debug_mount,	.kill_sb =	kill_litter_super,}; static struct dentry *__create_file(const char *name, umode_t mode,				    struct dentry *parent, void *data,				    const struct file_operations *fops){	struct dentry *dentry = NULL;	int error; 	pr_debug("debugfs: creating file '%s'\n",name); 	error = simple_pin_fs(&debug_fs_type, &debugfs_mount,			      &debugfs_mount_count);	if (error)		goto exit; 	/* If the parent is not specified, we create it in the root.	 * We need the root dentry to do this, which is in the super 	 * block. A pointer to that is in the struct vfsmount that we	 * have around.	 */	if (!parent)		parent = debugfs_mount->mnt_root; 	dentry = NULL;	mutex_lock(&parent->d_inode->i_mutex);	dentry = lookup_one_len(name, parent, strlen(name));	if (!IS_ERR(dentry)) {		switch (mode & S_IFMT) {		case S_IFDIR:			error = debugfs_mkdir(parent->d_inode, dentry, mode);					      			break;		case S_IFLNK:			error = debugfs_link(parent->d_inode, dentry, mode,					     data);			break;		default:			error = debugfs_create(parent->d_inode, dentry, mode,					       data, fops);			break;		}		dput(dentry);	} else		error = PTR_ERR(dentry);	mutex_unlock(&parent->d_inode->i_mutex); 	if (error) {		dentry = NULL;		simple_release_fs(&debugfs_mount, &debugfs_mount_count);	}exit:	return dentry;} /** * debugfs_create_file - create a file in the debugfs filesystem * @name: a pointer to a string containing the name of the file to create. * @mode: the permission that the file should have. * @parent: a pointer to the parent dentry for this file.  This should be a *          directory dentry if set.  If this paramater is NULL, then the *          file will be created in the root of the debugfs filesystem. * @data: a pointer to something that the caller will want to get to later *        on.  The inode.i_private pointer will point to this value on *        the open() call. * @fops: a pointer to a struct file_operations that should be used for *        this file. * * This is the basic "create a file" function for debugfs.  It allows for a * wide range of flexibility in creating a file, or a directory (if you want * to create a directory, the debugfs_create_dir() function is * recommended to be used instead.) * * This function will return a pointer to a dentry if it succeeds.  This * pointer must be passed to the debugfs_remove() function when the file is * to be removed (no automatic cleanup happens if your module is unloaded, * you are responsible here.)  If an error occurs, %NULL will be returned. * * If debugfs is not enabled in the kernel, the value -%ENODEV will be * returned. */struct dentry *debugfs_create_file(const char *name, umode_t mode,				   struct dentry *parent, void *data,				   const struct file_operations *fops){	switch (mode & S_IFMT) {	case S_IFREG:	case 0:		break;	default:		BUG();	} 	return __create_file(name, mode, parent, data, fops);}EXPORT_SYMBOL_GPL(debugfs_create_file); /** * debugfs_create_dir - create a directory in the debugfs filesystem * @name: a pointer to a string containing the name of the directory to *        create. * @parent: a pointer to the parent dentry for this file.  This should be a *          directory dentry if set.  If this paramater is NULL, then the *          directory will be created in the root of the debugfs filesystem. * * This function creates a directory in debugfs with the given name. * * This function will return a pointer to a dentry if it succeeds.  This * pointer must be passed to the debugfs_remove() function when the file is * to be removed (no automatic cleanup happens if your module is unloaded, * you are responsible here.)  If an error occurs, %NULL will be returned. * * If debugfs is not enabled in the kernel, the value -%ENODEV will be * returned. */struct dentry *debugfs_create_dir(const char *name, struct dentry *parent){	return __create_file(name, S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,				   parent, NULL, NULL);}EXPORT_SYMBOL_GPL(debugfs_create_dir); /** * debugfs_create_symlink- create a symbolic link in the debugfs filesystem * @name: a pointer to a string containing the name of the symbolic link to *        create. * @parent: a pointer to the parent dentry for this symbolic link.  This *          should be a directory dentry if set.  If this paramater is NULL, *          then the symbolic link will be created in the root of the debugfs *          filesystem. * @target: a pointer to a string containing the path to the target of the *          symbolic link. * * This function creates a symbolic link with the given name in debugfs that * links to the given target path. * * This function will return a pointer to a dentry if it succeeds.  This * pointer must be passed to the debugfs_remove() function when the symbolic * link is to be removed (no automatic cleanup happens if your module is * unloaded, you are responsible here.)  If an error occurs, %NULL will be * returned. * * If debugfs is not enabled in the kernel, the value -%ENODEV will be * returned. */struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,				      const char *target){	struct dentry *result;	char *link; 	link = kstrdup(target, GFP_KERNEL);	if (!link)		return NULL; 	result = __create_file(name, S_IFLNK | S_IRWXUGO, parent, link, NULL);	if (!result)		kfree(link);	return result;}EXPORT_SYMBOL_GPL(debugfs_create_symlink); static int __debugfs_remove(struct dentry *dentry, struct dentry *parent){	int ret = 0; 	if (debugfs_positive(dentry)) {		if (dentry->d_inode) {			dget(dentry);			switch (dentry->d_inode->i_mode & S_IFMT) {			case S_IFDIR:				ret = simple_rmdir(parent->d_inode, dentry);				break;			case S_IFLNK:				kfree(dentry->d_inode->i_private);				/* fall through */			default:				simple_unlink(parent->d_inode, dentry);				break;			}			if (!ret)				d_delete(dentry);			dput(dentry);		}	}	return ret;} /** * debugfs_remove - removes a file or directory from the debugfs filesystem * @dentry: a pointer to a the dentry of the file or directory to be *          removed. * * This function removes a file or directory in debugfs that was previously * created with a call to another debugfs function (like * debugfs_create_file() or variants thereof.) * * This function is required to be called in order for the file to be * removed, no automatic cleanup of files will happen when a module is

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