/* * 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> #define SECURITYFS_MAGIC 0x73636673 static struct vfsmount *mount; static int mount_count; /* * TODO: * I think I can get rid of these default_file_ops, but not quite sure... */ static ssize_t default_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos) { return 0; } static ssize_t default_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { return count; } static int default_open(struct inode *inode, struct file *file) { if (inode->i_private) file->private_data = inode->i_private; return 0; } static const struct file_operations default_file_ops = { .read = default_read_file, .write = default_write_file, .open = default_open, }; static struct inode *get_inode(struct super_block *sb, int mode, dev_t dev) { struct inode *inode = new_inode(sb); if (inode) { inode->i_mode = mode; inode->i_uid = 0; inode->i_gid = 0; inode->i_blocks = 0; 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 = &default_file_ops; break; case S_IFDIR: inode->i_op = &simple_dir_inode_operations; inode->i_fop = &simple_dir_operations; /* directory inodes start off with i_nlink == 2 (for "." entry) */ inc_nlink(inode); break; } } return inode; } /* SMP-safe */ static int mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) { struct inode *inode; int error = -EPERM; if (dentry->d_inode) return -EEXIST; inode = get_inode(dir->i_sb, mode, dev); if (inode) { d_instantiate(dentry, inode); dget(dentry); error = 0; } return error; } static int mkdir(struct inode *dir, struct dentry *dentry, int mode) { int res; mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR; res = mknod(dir, dentry, mode, 0); if (!res) inc_nlink(dir); return res; } static int create(struct inode *dir, struct dentry *dentry, int mode) { mode = (mode & S_IALLUGO) | S_IFREG; return mknod(dir, dentry, mode, 0); } 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 int get_sb(struct file_system_type *fs_type, int flags, const char *dev_name, void *data, struct vfsmount *mnt) { return get_sb_single(fs_type, flags, data, fill_super, mnt); } static struct file_system_type fs_type = { .owner = THIS_MODULE, .name = "securityfs", .get_sb = get_sb, .kill_sb = kill_litter_super, }; static int create_by_name(const char *name, mode_t mode, struct dentry *parent, struct dentry **dentry) { int error = 0; *dentry = NULL; /* 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 ) { if (mount && mount->mnt_sb) { parent = mount->mnt_sb->s_root; } } if (!parent) { pr_debug("securityfs: Ah! can not find a parent!\n"); return -EFAULT; } mutex_lock(&parent->d_inode->i_mutex); *dentry = lookup_one_len(name, parent, strlen(name)); if (!IS_ERR(dentry)) { if ((mode & S_IFMT) == S_IFDIR) error = mkdir(parent->d_inode, *dentry, mode); else error = create(parent->d_inode, *dentry, mode); } else error = PTR_ERR(dentry); mutex_unlock(&parent->d_inode->i_mutex); return error; } /** * 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 paramater 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 createing 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 will return 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 will be * 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_file(const char *name, mode_t mode, struct dentry *parent, void *data, const struct file_operations *fops) { struct dentry *dentry = NULL; int error; pr_debug("securityfs: creating file '%s'\n",name); error = simple_pin_fs(&fs_type, &mount, &mount_count); if (error) { dentry = ERR_PTR(error); goto exit; } error = create_by_name(name, mode, parent, &dentry); if (error) { dentry = ERR_PTR(error); simple_release_fs(&mount, &mount_count); goto exit; } if (dentry->d_inode) { if (fops) dentry->d_inode->i_fop = fops; if (data) dentry->d_inode->i_private = data; } exit: 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 paramater 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 will return 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 will be * 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) 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 decl_subsys(security, NULL, NULL); static int __init securityfs_init(void) { int retval; kobj_set_kset_s(&security_subsys, kernel_subsys); retval = subsystem_register(&security_subsys); if (retval) return retval; retval = register_filesystem(&fs_type); if (retval) subsystem_unregister(&security_subsys); return retval; } core_initcall(securityfs_init); MODULE_LICENSE("GPL");