/* * inode.c - securityfs * * Copyright (C) 2005 Greg Kroah-Hartman <gregkh@suse.de> * * 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. * * Based on fs/debugfs/inode.c which had the following copyright notice: * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com> * Copyright (C) 2004 IBM Inc. */ /* #define DEBUG */ #include <linux/module.h> #include <linux/fs.h> #include <linux/mount.h> #include <linux/pagemap.h> #include <linux/init.h> #include <linux/namei.h> #include <linux/security.h> #include <linux/magic.h> static struct vfsmount *mount; static int mount_count; static inline int positive(struct dentry *dentry) { return dentry->d_inode && !d_unhashed(dentry); } static int fill_super(struct super_block *sb, void *data, int silent) { static struct tree_descr files[] = {{""}}; return simple_fill_super(sb, SECURITYFS_MAGIC, files); } static struct dentry *get_sb(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { return mount_single(fs_type, flags, data, fill_super); } static struct file_system_type fs_type = { .owner = THIS_MODULE, .name = "securityfs", .mount = get_sb, .kill_sb = kill_litter_super, }; /** * securityfs_create_file - create a file in the securityfs 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 securityfs 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 securityfs. It allows for a * wide range of flexibility in creating a file, or a directory (if you * want to create a directory, the securityfs_create_dir() function is * recommended to be used instead). * * This function returns a pointer to a dentry if it succeeds. This * pointer must be passed to the securityfs_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, the function will return * the erorr value (via ERR_PTR). * * If securityfs is not enabled in the kernel, the value %-ENODEV is * returned. */ struct dentry *securityfs_create_file(const char *name, umode_t mode, struct dentry *parent, void *data, const struct file_operations *fops) { struct dentry *dentry; int is_dir = S_ISDIR(mode); struct inode *dir, *inode; int error; if (!is_dir) { BUG_ON(!fops); mode = (mode & S_IALLUGO) | S_IFREG; } pr_debug("securityfs: creating file '%s'\n",name); error = simple_pin_fs(&fs_type, &mount, &mount_count); if (error) return ERR_PTR(error); if (!parent) parent = mount->mnt_root; dir = parent->d_inode; mutex_lock(&dir->i_mutex); dentry = lookup_one_len(name, parent, strlen(name)); if (IS_ERR(dentry)) goto out; if (dentry->d_inode) { error = -EEXIST; goto out1; } inode = new_inode(dir->i_sb); if (!inode) { error = -ENOMEM; goto out1; } inode->i_ino = get_next_ino(); inode->i_mode = mode; inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; inode->i_private = data; if (is_dir) { inode->i_op = &simple_dir_inode_operations; inode->i_fop = &simple_dir_operations; inc_nlink(inode); inc_nlink(dir); } else { inode->i_fop = fops; } d_instantiate(dentry, inode); dget(dentry); mutex_unlock(&dir->i_mutex); return dentry; out1: dput(dentry); dentry = ERR_PTR(error); out: mutex_unlock(&dir->i_mutex); simple_release_fs(&mount, &mount_count); return dentry; } EXPORT_SYMBOL_GPL(securityfs_create_file); /** * securityfs_create_dir - create a directory in the securityfs 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 securityfs filesystem. * * This function creates a directory in securityfs with the given @name. * * This function returns a pointer to a dentry if it succeeds. This * pointer must be passed to the securityfs_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 securityfs is not enabled in the kernel, the value %-ENODEV is * returned. It is not wise to check for this value, but rather, check for * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling * code. */ struct dentry *securityfs_create_dir(const char *name, struct dentry *parent) { return securityfs_create_file(name, S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO, parent, NULL, NULL); } EXPORT_SYMBOL_GPL(securityfs_create_dir); /** * securityfs_remove - removes a file or directory from the securityfs filesystem * * @dentry: a pointer to a the dentry of the file or directory to be removed. * * This function removes a file or directory in securityfs that was previously * created with a call to another securityfs function (like * securityfs_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 * removed; you are responsible here. */ void securityfs_remove(struct dentry *dentry) { struct dentry *parent; if (!dentry || IS_ERR(dentry)) return; parent = dentry->d_parent; if (!parent || !parent->d_inode) return; mutex_lock(&parent->d_inode->i_mutex); if (positive(dentry)) { if (dentry->d_inode) { if (S_ISDIR(dentry->d_inode->i_mode)) simple_rmdir(parent->d_inode, dentry); else simple_unlink(parent->d_inode, dentry); dput(dentry); } } mutex_unlock(&parent->d_inode->i_mutex); simple_release_fs(&mount, &mount_count); } EXPORT_SYMBOL_GPL(securityfs_remove); static struct kobject *security_kobj; static int __init securityfs_init(void) { int retval; security_kobj = kobject_create_and_add("security", kernel_kobj); if (!security_kobj) return -EINVAL; retval = register_filesystem(&fs_type); if (retval) kobject_put(security_kobj); return retval; } core_initcall(securityfs_init); MODULE_LICENSE("GPL");