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![Casey Schaufler](/assets/img/avatar_default.png)
I am still tired of having to find indirect ways to determine what security modules are active on a system. I have added /sys/kernel/security/lsm, which contains a comma separated list of the active security modules. No more groping around in /proc/filesystems or other clever hacks. Unchanged from previous versions except for being updated to the latest security next branch. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> Acked-by: John Johansen <john.johansen@canonical.com> Acked-by: Paul Moore <paul@paul-moore.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <james.l.morris@oracle.com>
245 lines
6.8 KiB
C
245 lines
6.8 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version
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* 2 as published by the Free Software Foundation.
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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/module.h>
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#include <linux/fs.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 int fill_super(struct super_block *sb, void *data, int silent)
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{
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static struct tree_descr files[] = {{""}};
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return simple_fill_super(sb, SECURITYFS_MAGIC, files);
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}
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static struct dentry *get_sb(struct file_system_type *fs_type,
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int flags, const char *dev_name,
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void *data)
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{
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return mount_single(fs_type, flags, data, fill_super);
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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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.mount = get_sb,
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.kill_sb = kill_litter_super,
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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 is the basic "create a file" function for securityfs. It allows for a
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* wide range of flexibility in creating a file, or a directory (if you
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* want to create a directory, the securityfs_create_dir() function is
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* recommended to be used 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 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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struct dentry *dentry;
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int is_dir = S_ISDIR(mode);
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struct inode *dir, *inode;
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int error;
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if (!is_dir) {
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BUG_ON(!fops);
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mode = (mode & S_IALLUGO) | S_IFREG;
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}
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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->i_ctime = current_time(inode);
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inode->i_private = data;
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if (is_dir) {
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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 {
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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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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,
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S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
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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_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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MODULE_LICENSE("GPL");
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