1/*
  2 * Copyright (C) 2008 IBM Corporation
  3 *
  4 * Authors:
  5 * Mimi Zohar <zohar@us.ibm.com>
  6 *
  7 * This program is free software; you can redistribute it and/or
  8 * modify it under the terms of the GNU General Public License as
  9 * published by the Free Software Foundation, version 2 of the
 10 * License.
 11 *
 12 * File: integrity_iint.c
 13 *	- implements the integrity hooks: integrity_inode_alloc,
 14 *	  integrity_inode_free
 15 *	- cache integrity information associated with an inode
 16 *	  using a rbtree tree.
 17 */
 18#include <linux/slab.h>
 19#include <linux/module.h>
 20#include <linux/spinlock.h>
 21#include <linux/rbtree.h>
 22#include "integrity.h"
 23
 24static struct rb_root integrity_iint_tree = RB_ROOT;
 25static DEFINE_RWLOCK(integrity_iint_lock);
 26static struct kmem_cache *iint_cache __read_mostly;
 27
 28int iint_initialized;
 29
 30/*
 31 * __integrity_iint_find - return the iint associated with an inode
 32 */
 33static struct integrity_iint_cache *__integrity_iint_find(struct inode *inode)
 34{
 35	struct integrity_iint_cache *iint;
 36	struct rb_node *n = integrity_iint_tree.rb_node;
 37
 38	while (n) {
 39		iint = rb_entry(n, struct integrity_iint_cache, rb_node);
 40
 41		if (inode < iint->inode)
 42			n = n->rb_left;
 43		else if (inode > iint->inode)
 44			n = n->rb_right;
 45		else
 46			break;
 47	}
 48	if (!n)
 49		return NULL;
 50
 51	return iint;
 52}
 53
 54/*
 55 * integrity_iint_find - return the iint associated with an inode
 56 */
 57struct integrity_iint_cache *integrity_iint_find(struct inode *inode)
 58{
 59	struct integrity_iint_cache *iint;
 60
 61	if (!IS_IMA(inode))
 62		return NULL;
 63
 64	read_lock(&integrity_iint_lock);
 65	iint = __integrity_iint_find(inode);
 66	read_unlock(&integrity_iint_lock);
 67
 68	return iint;
 69}
 70
 71static void iint_free(struct integrity_iint_cache *iint)
 72{
 73	kfree(iint->ima_hash);
 74	iint->ima_hash = NULL;
 75	iint->version = 0;
 76	iint->flags = 0UL;
 77	iint->ima_file_status = INTEGRITY_UNKNOWN;
 78	iint->ima_mmap_status = INTEGRITY_UNKNOWN;
 79	iint->ima_bprm_status = INTEGRITY_UNKNOWN;
 80	iint->ima_module_status = INTEGRITY_UNKNOWN;
 81	iint->evm_status = INTEGRITY_UNKNOWN;
 82	kmem_cache_free(iint_cache, iint);
 83}
 84
 85/**
 86 * integrity_inode_get - find or allocate an iint associated with an inode
 87 * @inode: pointer to the inode
 88 * @return: allocated iint
 89 *
 90 * Caller must lock i_mutex
 91 */
 92struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
 93{
 94	struct rb_node **p;
 95	struct rb_node *node, *parent = NULL;
 96	struct integrity_iint_cache *iint, *test_iint;
 97
 98	iint = integrity_iint_find(inode);
 99	if (iint)
100		return iint;
101
102	iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
103	if (!iint)
104		return NULL;
105
106	write_lock(&integrity_iint_lock);
107
108	p = &integrity_iint_tree.rb_node;
109	while (*p) {
110		parent = *p;
111		test_iint = rb_entry(parent, struct integrity_iint_cache,
112				     rb_node);
113		if (inode < test_iint->inode)
114			p = &(*p)->rb_left;
115		else
116			p = &(*p)->rb_right;
117	}
118
119	iint->inode = inode;
120	node = &iint->rb_node;
121	inode->i_flags |= S_IMA;
122	rb_link_node(node, parent, p);
123	rb_insert_color(node, &integrity_iint_tree);
124
125	write_unlock(&integrity_iint_lock);
126	return iint;
127}
128
129/**
130 * integrity_inode_free - called on security_inode_free
131 * @inode: pointer to the inode
132 *
133 * Free the integrity information(iint) associated with an inode.
134 */
135void integrity_inode_free(struct inode *inode)
136{
137	struct integrity_iint_cache *iint;
138
139	if (!IS_IMA(inode))
140		return;
141
142	write_lock(&integrity_iint_lock);
143	iint = __integrity_iint_find(inode);
144	rb_erase(&iint->rb_node, &integrity_iint_tree);
145	write_unlock(&integrity_iint_lock);
146
147	iint_free(iint);
148}
149
150static void init_once(void *foo)
151{
152	struct integrity_iint_cache *iint = foo;
153
154	memset(iint, 0, sizeof(*iint));
155	iint->version = 0;
156	iint->flags = 0UL;
157	iint->ima_file_status = INTEGRITY_UNKNOWN;
158	iint->ima_mmap_status = INTEGRITY_UNKNOWN;
159	iint->ima_bprm_status = INTEGRITY_UNKNOWN;
160	iint->ima_module_status = INTEGRITY_UNKNOWN;
161	iint->evm_status = INTEGRITY_UNKNOWN;
162}
163
164static int __init integrity_iintcache_init(void)
165{
166	iint_cache =
167	    kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
168			      0, SLAB_PANIC, init_once);
169	iint_initialized = 1;
170	return 0;
171}
172security_initcall(integrity_iintcache_init);