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 <linux/file.h>
 23#include <linux/uaccess.h>
 24#include "integrity.h"
 25
 26static struct rb_root integrity_iint_tree = RB_ROOT;
 27static DEFINE_RWLOCK(integrity_iint_lock);
 28static struct kmem_cache *iint_cache __read_mostly;
 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->atomic_flags = 0UL;
 78	iint->ima_file_status = INTEGRITY_UNKNOWN;
 79	iint->ima_mmap_status = INTEGRITY_UNKNOWN;
 80	iint->ima_bprm_status = INTEGRITY_UNKNOWN;
 81	iint->ima_read_status = INTEGRITY_UNKNOWN;
 82	iint->ima_creds_status = INTEGRITY_UNKNOWN;
 83	iint->evm_status = INTEGRITY_UNKNOWN;
 84	iint->measured_pcrs = 0;
 85	kmem_cache_free(iint_cache, iint);
 86}
 87
 88/**
 89 * integrity_inode_get - find or allocate an iint associated with an inode
 90 * @inode: pointer to the inode
 91 * @return: allocated iint
 92 *
 93 * Caller must lock i_mutex
 94 */
 95struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
 96{
 97	struct rb_node **p;
 98	struct rb_node *node, *parent = NULL;
 99	struct integrity_iint_cache *iint, *test_iint;
100
101	iint = integrity_iint_find(inode);
102	if (iint)
103		return iint;
104
105	iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
106	if (!iint)
107		return NULL;
108
109	write_lock(&integrity_iint_lock);
110
111	p = &integrity_iint_tree.rb_node;
112	while (*p) {
113		parent = *p;
114		test_iint = rb_entry(parent, struct integrity_iint_cache,
115				     rb_node);
116		if (inode < test_iint->inode)
117			p = &(*p)->rb_left;
118		else
119			p = &(*p)->rb_right;
120	}
121
122	iint->inode = inode;
123	node = &iint->rb_node;
124	inode->i_flags |= S_IMA;
125	rb_link_node(node, parent, p);
126	rb_insert_color(node, &integrity_iint_tree);
127
128	write_unlock(&integrity_iint_lock);
129	return iint;
130}
131
132/**
133 * integrity_inode_free - called on security_inode_free
134 * @inode: pointer to the inode
135 *
136 * Free the integrity information(iint) associated with an inode.
137 */
138void integrity_inode_free(struct inode *inode)
139{
140	struct integrity_iint_cache *iint;
141
142	if (!IS_IMA(inode))
143		return;
144
145	write_lock(&integrity_iint_lock);
146	iint = __integrity_iint_find(inode);
147	rb_erase(&iint->rb_node, &integrity_iint_tree);
148	write_unlock(&integrity_iint_lock);
149
150	iint_free(iint);
151}
152
153static void init_once(void *foo)
154{
155	struct integrity_iint_cache *iint = foo;
156
157	memset(iint, 0, sizeof(*iint));
158	iint->ima_file_status = INTEGRITY_UNKNOWN;
159	iint->ima_mmap_status = INTEGRITY_UNKNOWN;
160	iint->ima_bprm_status = INTEGRITY_UNKNOWN;
161	iint->ima_read_status = INTEGRITY_UNKNOWN;
162	iint->ima_creds_status = INTEGRITY_UNKNOWN;
163	iint->evm_status = INTEGRITY_UNKNOWN;
164	mutex_init(&iint->mutex);
165}
166
167static int __init integrity_iintcache_init(void)
168{
169	iint_cache =
170	    kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
171			      0, SLAB_PANIC, init_once);
172	return 0;
173}
174security_initcall(integrity_iintcache_init);
175
176
177/*
178 * integrity_kernel_read - read data from the file
179 *
180 * This is a function for reading file content instead of kernel_read().
181 * It does not perform locking checks to ensure it cannot be blocked.
182 * It does not perform security checks because it is irrelevant for IMA.
183 *
184 */
185int integrity_kernel_read(struct file *file, loff_t offset,
186			  void *addr, unsigned long count)
187{
188	mm_segment_t old_fs;
189	char __user *buf = (char __user *)addr;
190	ssize_t ret;
191
192	if (!(file->f_mode & FMODE_READ))
193		return -EBADF;
194
195	old_fs = get_fs();
196	set_fs(get_ds());
197	ret = __vfs_read(file, buf, count, &offset);
198	set_fs(old_fs);
199
200	return ret;
201}
202
203/*
204 * integrity_load_keys - load integrity keys hook
205 *
206 * Hooks is called from init/main.c:kernel_init_freeable()
207 * when rootfs is ready
208 */
209void __init integrity_load_keys(void)
210{
211	ima_load_x509();
212	evm_load_x509();
213}