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->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	return 0;
170}
171security_initcall(integrity_iintcache_init);
172
173
174/*
175 * integrity_kernel_read - read data from the file
176 *
177 * This is a function for reading file content instead of kernel_read().
178 * It does not perform locking checks to ensure it cannot be blocked.
179 * It does not perform security checks because it is irrelevant for IMA.
180 *
181 */
182int integrity_kernel_read(struct file *file, loff_t offset,
183			  char *addr, unsigned long count)
184{
185	mm_segment_t old_fs;
186	char __user *buf = (char __user *)addr;
187	ssize_t ret;
188
189	if (!(file->f_mode & FMODE_READ))
190		return -EBADF;
191
192	old_fs = get_fs();
193	set_fs(get_ds());
194	ret = __vfs_read(file, buf, count, &offset);
195	set_fs(old_fs);
196
197	return ret;
198}
199
200/*
201 * integrity_read_file - read entire file content into the buffer
202 *
203 * This is function opens a file, allocates the buffer of required
204 * size, read entire file content to the buffer and closes the file
205 *
206 * It is used only by init code.
207 *
208 */
209int __init integrity_read_file(const char *path, char **data)
210{
211	struct file *file;
212	loff_t size;
213	char *buf;
214	int rc = -EINVAL;
215
216	file = filp_open(path, O_RDONLY, 0);
217	if (IS_ERR(file)) {
218		rc = PTR_ERR(file);
219		pr_err("Unable to open file: %s (%d)", path, rc);
220		return rc;
221	}
222
223	size = i_size_read(file_inode(file));
224	if (size <= 0)
225		goto out;
226
227	buf = kmalloc(size, GFP_KERNEL);
228	if (!buf) {
229		rc = -ENOMEM;
230		goto out;
231	}
232
233	rc = integrity_kernel_read(file, 0, buf, size);
234	if (rc < 0)
235		kfree(buf);
236	else if (rc != size)
237		rc = -EIO;
238	else
239		*data = buf;
240out:
241	fput(file);
242	return rc;
243}
244
245/*
246 * integrity_load_keys - load integrity keys hook
247 *
248 * Hooks is called from init/main.c:kernel_init_freeable()
249 * when rootfs is ready
250 */
251void __init integrity_load_keys(void)
252{
253	ima_load_x509();
254}
255