blob: 7ec94314ac0ca28126b7c051d8663bbd1319f9de [file] [log] [blame]
Mimi Zohar3323eec2009-02-04 09:06:58 -05001/*
2 * Copyright (C) 2005,2006,2007,2008 IBM Corporation
3 *
4 * Authors:
5 * Serge Hallyn <serue@us.ibm.com>
6 * Reiner Sailer <sailer@watson.ibm.com>
7 * Mimi Zohar <zohar@us.ibm.com>
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License as
11 * published by the Free Software Foundation, version 2 of the
12 * License.
13 *
14 * File: ima_queue.c
15 * Implements queues that store template measurements and
16 * maintains aggregate over the stored measurements
17 * in the pre-configured TPM PCR (if available).
18 * The measurement list is append-only. No entry is
19 * ever removed or changed during the boot-cycle.
20 */
21#include <linux/module.h>
22#include <linux/rculist.h>
23#include "ima.h"
24
25LIST_HEAD(ima_measurements); /* list of all measurements */
26
27/* key: inode (before secure-hashing a file) */
28struct ima_h_table ima_htable = {
29 .len = ATOMIC_LONG_INIT(0),
30 .violations = ATOMIC_LONG_INIT(0),
31 .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT
32};
33
34/* mutex protects atomicity of extending measurement list
35 * and extending the TPM PCR aggregate. Since tpm_extend can take
36 * long (and the tpm driver uses a mutex), we can't use the spinlock.
37 */
38static DEFINE_MUTEX(ima_extend_list_mutex);
39
40/* lookup up the digest value in the hash table, and return the entry */
41static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value)
42{
43 struct ima_queue_entry *qe, *ret = NULL;
44 unsigned int key;
45 struct hlist_node *pos;
46 int rc;
47
48 key = ima_hash_key(digest_value);
49 rcu_read_lock();
50 hlist_for_each_entry_rcu(qe, pos, &ima_htable.queue[key], hnext) {
51 rc = memcmp(qe->entry->digest, digest_value, IMA_DIGEST_SIZE);
52 if (rc == 0) {
53 ret = qe;
54 break;
55 }
56 }
57 rcu_read_unlock();
58 return ret;
59}
60
61/* ima_add_template_entry helper function:
62 * - Add template entry to measurement list and hash table.
63 *
64 * (Called with ima_extend_list_mutex held.)
65 */
66static int ima_add_digest_entry(struct ima_template_entry *entry)
67{
68 struct ima_queue_entry *qe;
69 unsigned int key;
70
71 qe = kmalloc(sizeof(*qe), GFP_KERNEL);
72 if (qe == NULL) {
73 pr_err("OUT OF MEMORY ERROR creating queue entry.\n");
74 return -ENOMEM;
75 }
76 qe->entry = entry;
77
78 INIT_LIST_HEAD(&qe->later);
79 list_add_tail_rcu(&qe->later, &ima_measurements);
80
81 atomic_long_inc(&ima_htable.len);
82 key = ima_hash_key(entry->digest);
83 hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
84 return 0;
85}
86
87static int ima_pcr_extend(const u8 *hash)
88{
89 int result = 0;
90
91 if (!ima_used_chip)
92 return result;
93
94 result = tpm_pcr_extend(TPM_ANY_NUM, CONFIG_IMA_MEASURE_PCR_IDX, hash);
95 if (result != 0)
96 pr_err("Error Communicating to TPM chip\n");
97 return result;
98}
99
100/* Add template entry to the measurement list and hash table,
101 * and extend the pcr.
102 */
103int ima_add_template_entry(struct ima_template_entry *entry, int violation,
104 const char *op, struct inode *inode)
105{
106 u8 digest[IMA_DIGEST_SIZE];
107 const char *audit_cause = "hash_added";
108 int audit_info = 1;
109 int result = 0;
110
111 mutex_lock(&ima_extend_list_mutex);
112 if (!violation) {
113 memcpy(digest, entry->digest, sizeof digest);
114 if (ima_lookup_digest_entry(digest)) {
115 audit_cause = "hash_exists";
116 goto out;
117 }
118 }
119
120 result = ima_add_digest_entry(entry);
121 if (result < 0) {
122 audit_cause = "ENOMEM";
123 audit_info = 0;
124 goto out;
125 }
126
127 if (violation) /* invalidate pcr */
128 memset(digest, 0xff, sizeof digest);
129
130 result = ima_pcr_extend(digest);
131 if (result != 0) {
132 audit_cause = "TPM error";
133 audit_info = 0;
134 }
135out:
136 mutex_unlock(&ima_extend_list_mutex);
137 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, entry->template_name,
138 op, audit_cause, result, audit_info);
139 return result;
140}