/* *  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/core-api/kernel-api.rst 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>#include <linux/srcu.h> #include "internal.h" #define DEBUGFS_DEFAULT_MODE	0700 DEFINE_SRCU(debugfs_srcu); static struct vfsmount *debugfs_mount;static int debugfs_mount_count;static bool debugfs_registered; static struct inode *debugfs_get_inode(struct super_block *sb){	struct inode *inode = new_inode(sb);	if (inode) {		inode->i_ino = get_next_ino();		inode->i_atime = inode->i_mtime =			inode->i_ctime = current_time(inode);	}	return inode;} 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_int(&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 = d_inode(sb->s_root);	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; 	sync_filesystem(sb);	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 void debugfs_evict_inode(struct inode *inode){	truncate_inode_pages_final(&inode->i_data);	clear_inode(inode);	if (S_ISLNK(inode->i_mode))		kfree(inode->i_link);} static const struct super_operations debugfs_super_operations = {	.statfs		= simple_statfs,	.remount_fs	= debugfs_remount,	.show_options	= debugfs_show_options,	.evict_inode	= debugfs_evict_inode,}; static struct vfsmount *debugfs_automount(struct path *path){	debugfs_automount_t f;	f = (debugfs_automount_t)path->dentry->d_fsdata;	return f(path->dentry, d_inode(path->dentry)->i_private);} static const struct dentry_operations debugfs_dops = {	.d_delete = always_delete_dentry,	.d_automount = debugfs_automount,}; static int debug_fill_super(struct super_block *sb, void *data, int silent){	static const struct tree_descr debug_files[] = {{""}};	struct debugfs_fs_info *fsi;	int err; 	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;	sb->s_d_op = &debugfs_dops; 	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,};MODULE_ALIAS_FS("debugfs"); /** * debugfs_lookup() - look up an existing debugfs file * @name: a pointer to a string containing the name of the file to look up. * @parent: a pointer to the parent dentry of the file. * * This function will return a pointer to a dentry if it succeeds.  If the file * doesn't exist or an error occurs, %NULL will be returned.  The returned * dentry must be passed to dput() when it is no longer needed. * * If debugfs is not enabled in the kernel, the value -%ENODEV will be * returned. */struct dentry *debugfs_lookup(const char *name, struct dentry *parent){	struct dentry *dentry; 	if (IS_ERR(parent))		return NULL; 	if (!parent)		parent = debugfs_mount->mnt_root; 	inode_lock(d_inode(parent));	dentry = lookup_one_len(name, parent, strlen(name));	inode_unlock(d_inode(parent)); 	if (IS_ERR(dentry))		return NULL;	if (!d_really_is_positive(dentry)) {		dput(dentry);		return NULL;	}	return dentry;}EXPORT_SYMBOL_GPL(debugfs_lookup); static struct dentry *start_creating(const char *name, struct dentry *parent){	struct dentry *dentry;	int error; 	pr_debug("debugfs: creating file '%s'\n",name); 	if (IS_ERR(parent))		return parent; 	error = simple_pin_fs(&debug_fs_type, &debugfs_mount,			      &debugfs_mount_count);	if (error)		return ERR_PTR(error); 	/* 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; 	inode_lock(d_inode(parent));	dentry = lookup_one_len(name, parent, strlen(name));	if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {		dput(dentry);		dentry = ERR_PTR(-EEXIST);	} 	if (IS_ERR(dentry)) {		inode_unlock(d_inode(parent));		simple_release_fs(&debugfs_mount, &debugfs_mount_count);	} 	return dentry;} static struct dentry *failed_creating(struct dentry *dentry){	inode_unlock(d_inode(dentry->d_parent));	dput(dentry);	simple_release_fs(&debugfs_mount, &debugfs_mount_count);	return NULL;} static struct dentry *end_creating(struct dentry *dentry){	inode_unlock(d_inode(dentry->d_parent));	return dentry;} static struct dentry *__debugfs_create_file(const char *name, umode_t mode,				struct dentry *parent, void *data,				const struct file_operations *proxy_fops,				const struct file_operations *real_fops){	struct dentry *dentry;	struct inode *inode; 	if (!(mode & S_IFMT))		mode |= S_IFREG;	BUG_ON(!S_ISREG(mode));	dentry = start_creating(name, parent); 	if (IS_ERR(dentry))		return NULL; 	inode = debugfs_get_inode(dentry->d_sb);	if (unlikely(!inode))		return failed_creating(dentry); 	inode->i_mode = mode;	inode->i_private = data; 	inode->i_fop = proxy_fops;	dentry->d_fsdata = (void *)real_fops; 	d_instantiate(dentry, inode);	fsnotify_create(d_inode(dentry->d_parent), dentry);	return end_creating(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 parameter 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){ 	return __debugfs_create_file(name, mode, parent, data,				fops ? &debugfs_full_proxy_file_operations :					&debugfs_noop_file_operations,				fops);}EXPORT_SYMBOL_GPL(debugfs_create_file); /** * debugfs_create_file_unsafe - 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 parameter 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. * * debugfs_create_file_unsafe() is completely analogous to * debugfs_create_file(), the only difference being that the fops * handed it will not get protected against file removals by the * debugfs core. * * It is your responsibility to protect your struct file_operation * methods against file removals by means of debugfs_use_file_start() * and debugfs_use_file_finish(). ->open() is still protected by * debugfs though. * * Any struct file_operations defined by means of * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and * thus, may be used here. */struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,				   struct dentry *parent, void *data,				   const struct file_operations *fops){ 	return __debugfs_create_file(name, mode, parent, data,				fops ? &debugfs_open_proxy_file_operations :					&debugfs_noop_file_operations,				fops);}EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe); /** * debugfs_create_file_size - 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 parameter 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. * @file_size: initial file size * * 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_size(const char *name, umode_t mode,					struct dentry *parent, void *data,					const struct file_operations *fops,					loff_t file_size){	struct dentry *de = debugfs_create_file(name, mode, parent, data, fops); 	if (de)		d_inode(de)->i_size = file_size;	return de;}EXPORT_SYMBOL_GPL(debugfs_create_file_size); /** * 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 parameter 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

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