351 lines
11 KiB
C
351 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* inode.c - securityfs
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*
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* Copyright (C) 2005 Greg Kroah-Hartman <gregkh@suse.de>
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*
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* Based on fs/debugfs/inode.c which had the following copyright notice:
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* Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
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* Copyright (C) 2004 IBM Inc.
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*/
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/* #define DEBUG */
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#include <linux/sysfs.h>
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#include <linux/kobject.h>
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#include <linux/fs.h>
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#include <linux/fs_context.h>
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#include <linux/mount.h>
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#include <linux/pagemap.h>
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#include <linux/init.h>
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#include <linux/namei.h>
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#include <linux/security.h>
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#include <linux/lsm_hooks.h>
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#include <linux/magic.h>
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static struct vfsmount *mount;
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static int mount_count;
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static void securityfs_free_inode(struct inode *inode)
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{
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if (S_ISLNK(inode->i_mode))
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kfree(inode->i_link);
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free_inode_nonrcu(inode);
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}
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static const struct super_operations securityfs_super_operations = {
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.statfs = simple_statfs,
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.free_inode = securityfs_free_inode,
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};
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static int securityfs_fill_super(struct super_block *sb, struct fs_context *fc)
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{
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static const struct tree_descr files[] = {{""}};
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int error;
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error = simple_fill_super(sb, SECURITYFS_MAGIC, files);
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if (error)
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return error;
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sb->s_op = &securityfs_super_operations;
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return 0;
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}
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static int securityfs_get_tree(struct fs_context *fc)
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{
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return get_tree_single(fc, securityfs_fill_super);
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}
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static const struct fs_context_operations securityfs_context_ops = {
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.get_tree = securityfs_get_tree,
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};
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static int securityfs_init_fs_context(struct fs_context *fc)
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{
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fc->ops = &securityfs_context_ops;
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return 0;
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}
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static struct file_system_type fs_type = {
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.owner = THIS_MODULE,
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.name = "securityfs",
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.init_fs_context = securityfs_init_fs_context,
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.kill_sb = kill_litter_super,
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};
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/**
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* securityfs_create_dentry - create a dentry in the securityfs filesystem
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*
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* @name: a pointer to a string containing the name of the file to create.
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* @mode: the permission that the file should have
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* @parent: a pointer to the parent dentry for this file. This should be a
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* directory dentry if set. If this parameter is %NULL, then the
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* file will be created in the root of the securityfs filesystem.
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* @data: a pointer to something that the caller will want to get to later
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* on. The inode.i_private pointer will point to this value on
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* the open() call.
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* @fops: a pointer to a struct file_operations that should be used for
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* this file.
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* @iops: a point to a struct of inode_operations that should be used for
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* this file/dir
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*
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* This is the basic "create a file/dir/symlink" function for
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* securityfs. It allows for a wide range of flexibility in creating
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* a file, or a directory (if you want to create a directory, the
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* securityfs_create_dir() function is recommended to be used
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* instead).
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*
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* This function returns a pointer to a dentry if it succeeds. This
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* pointer must be passed to the securityfs_remove() function when the
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* file is to be removed (no automatic cleanup happens if your module
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* is unloaded, you are responsible here). If an error occurs, the
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* function will return the error value (via ERR_PTR).
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*
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* If securityfs is not enabled in the kernel, the value %-ENODEV is
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* returned.
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*/
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static struct dentry *securityfs_create_dentry(const char *name, umode_t mode,
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struct dentry *parent, void *data,
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const struct file_operations *fops,
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const struct inode_operations *iops)
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{
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struct dentry *dentry;
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struct inode *dir, *inode;
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int error;
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if (!(mode & S_IFMT))
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mode = (mode & S_IALLUGO) | S_IFREG;
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pr_debug("securityfs: creating file '%s'\n",name);
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error = simple_pin_fs(&fs_type, &mount, &mount_count);
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if (error)
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return ERR_PTR(error);
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if (!parent)
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parent = mount->mnt_root;
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dir = d_inode(parent);
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inode_lock(dir);
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dentry = lookup_one_len(name, parent, strlen(name));
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if (IS_ERR(dentry))
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goto out;
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if (d_really_is_positive(dentry)) {
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error = -EEXIST;
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goto out1;
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}
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inode = new_inode(dir->i_sb);
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if (!inode) {
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error = -ENOMEM;
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goto out1;
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}
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inode->i_ino = get_next_ino();
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inode->i_mode = mode;
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inode->i_atime = inode->i_mtime = inode_set_ctime_current(inode);
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inode->i_private = data;
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if (S_ISDIR(mode)) {
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inode->i_op = &simple_dir_inode_operations;
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inode->i_fop = &simple_dir_operations;
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inc_nlink(inode);
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inc_nlink(dir);
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} else if (S_ISLNK(mode)) {
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inode->i_op = iops ? iops : &simple_symlink_inode_operations;
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inode->i_link = data;
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} else {
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inode->i_fop = fops;
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}
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d_instantiate(dentry, inode);
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dget(dentry);
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inode_unlock(dir);
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return dentry;
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out1:
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dput(dentry);
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dentry = ERR_PTR(error);
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out:
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inode_unlock(dir);
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simple_release_fs(&mount, &mount_count);
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return dentry;
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}
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/**
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* securityfs_create_file - create a file in the securityfs filesystem
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*
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* @name: a pointer to a string containing the name of the file to create.
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* @mode: the permission that the file should have
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* @parent: a pointer to the parent dentry for this file. This should be a
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* directory dentry if set. If this parameter is %NULL, then the
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* file will be created in the root of the securityfs filesystem.
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* @data: a pointer to something that the caller will want to get to later
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* on. The inode.i_private pointer will point to this value on
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* the open() call.
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* @fops: a pointer to a struct file_operations that should be used for
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* this file.
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*
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* This function creates a file in securityfs with the given @name.
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*
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* This function returns a pointer to a dentry if it succeeds. This
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* pointer must be passed to the securityfs_remove() function when the file is
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* to be removed (no automatic cleanup happens if your module is unloaded,
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* you are responsible here). If an error occurs, the function will return
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* the error value (via ERR_PTR).
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*
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* If securityfs is not enabled in the kernel, the value %-ENODEV is
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* returned.
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*/
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struct dentry *securityfs_create_file(const char *name, umode_t mode,
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struct dentry *parent, void *data,
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const struct file_operations *fops)
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{
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return securityfs_create_dentry(name, mode, parent, data, fops, NULL);
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}
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EXPORT_SYMBOL_GPL(securityfs_create_file);
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/**
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* securityfs_create_dir - create a directory in the securityfs filesystem
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*
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* @name: a pointer to a string containing the name of the directory to
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* create.
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* @parent: a pointer to the parent dentry for this file. This should be a
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* directory dentry if set. If this parameter is %NULL, then the
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* directory will be created in the root of the securityfs filesystem.
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*
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* This function creates a directory in securityfs with the given @name.
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*
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* This function returns a pointer to a dentry if it succeeds. This
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* pointer must be passed to the securityfs_remove() function when the file is
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* to be removed (no automatic cleanup happens if your module is unloaded,
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* you are responsible here). If an error occurs, the function will return
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* the error value (via ERR_PTR).
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*
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* If securityfs is not enabled in the kernel, the value %-ENODEV is
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* returned.
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*/
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struct dentry *securityfs_create_dir(const char *name, struct dentry *parent)
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{
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return securityfs_create_file(name, S_IFDIR | 0755, parent, NULL, NULL);
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}
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EXPORT_SYMBOL_GPL(securityfs_create_dir);
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/**
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* securityfs_create_symlink - create a symlink in the securityfs filesystem
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*
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* @name: a pointer to a string containing the name of the symlink to
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* create.
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* @parent: a pointer to the parent dentry for the symlink. This should be a
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* directory dentry if set. If this parameter is %NULL, then the
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* directory will be created in the root of the securityfs filesystem.
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* @target: a pointer to a string containing the name of the symlink's target.
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* If this parameter is %NULL, then the @iops parameter needs to be
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* setup to handle .readlink and .get_link inode_operations.
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* @iops: a pointer to the struct inode_operations to use for the symlink. If
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* this parameter is %NULL, then the default simple_symlink_inode
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* operations will be used.
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*
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* This function creates a symlink in securityfs with the given @name.
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*
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* This function returns a pointer to a dentry if it succeeds. This
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* pointer must be passed to the securityfs_remove() function when the file is
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* to be removed (no automatic cleanup happens if your module is unloaded,
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* you are responsible here). If an error occurs, the function will return
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* the error value (via ERR_PTR).
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*
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* If securityfs is not enabled in the kernel, the value %-ENODEV is
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* returned.
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*/
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struct dentry *securityfs_create_symlink(const char *name,
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struct dentry *parent,
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const char *target,
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const struct inode_operations *iops)
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{
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struct dentry *dent;
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char *link = NULL;
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if (target) {
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link = kstrdup(target, GFP_KERNEL);
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if (!link)
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return ERR_PTR(-ENOMEM);
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}
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dent = securityfs_create_dentry(name, S_IFLNK | 0444, parent,
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link, NULL, iops);
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if (IS_ERR(dent))
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kfree(link);
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return dent;
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}
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EXPORT_SYMBOL_GPL(securityfs_create_symlink);
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/**
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* securityfs_remove - removes a file or directory from the securityfs filesystem
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*
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* @dentry: a pointer to a the dentry of the file or directory to be removed.
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*
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* This function removes a file or directory in securityfs that was previously
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* created with a call to another securityfs function (like
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* securityfs_create_file() or variants thereof.)
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*
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* This function is required to be called in order for the file to be
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* removed. No automatic cleanup of files will happen when a module is
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* removed; you are responsible here.
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*/
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void securityfs_remove(struct dentry *dentry)
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{
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struct inode *dir;
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if (!dentry || IS_ERR(dentry))
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return;
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dir = d_inode(dentry->d_parent);
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inode_lock(dir);
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if (simple_positive(dentry)) {
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if (d_is_dir(dentry))
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simple_rmdir(dir, dentry);
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else
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simple_unlink(dir, dentry);
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dput(dentry);
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}
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inode_unlock(dir);
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simple_release_fs(&mount, &mount_count);
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}
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EXPORT_SYMBOL_GPL(securityfs_remove);
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#ifdef CONFIG_SECURITY
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static struct dentry *lsm_dentry;
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static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count,
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loff_t *ppos)
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{
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return simple_read_from_buffer(buf, count, ppos, lsm_names,
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strlen(lsm_names));
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}
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static const struct file_operations lsm_ops = {
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.read = lsm_read,
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.llseek = generic_file_llseek,
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};
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#endif
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static int __init securityfs_init(void)
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{
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int retval;
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retval = sysfs_create_mount_point(kernel_kobj, "security");
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if (retval)
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return retval;
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retval = register_filesystem(&fs_type);
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if (retval) {
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sysfs_remove_mount_point(kernel_kobj, "security");
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return retval;
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}
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#ifdef CONFIG_SECURITY
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lsm_dentry = securityfs_create_file("lsm", 0444, NULL, NULL,
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&lsm_ops);
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#endif
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return 0;
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}
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core_initcall(securityfs_init);
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