1 /*
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 <linux/slab.h>
24 #include "ima.h"
25
26 LIST_HEAD(ima_measurements); /* list of all measurements */
27
28 /* key: inode (before secure-hashing a file) */
29 struct ima_h_table ima_htable = {
30 .len = ATOMIC_LONG_INIT(0),
31 .violations = ATOMIC_LONG_INIT(0),
32 .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT
33 };
34
35 /* mutex protects atomicity of extending measurement list
36 * and extending the TPM PCR aggregate. Since tpm_extend can take
37 * long (and the tpm driver uses a mutex), we can't use the spinlock.
38 */
39 static DEFINE_MUTEX(ima_extend_list_mutex);
40
41 /* lookup up the digest value in the hash table, and return the entry */
ima_lookup_digest_entry(u8 * digest_value)42 static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value)
43 {
44 struct ima_queue_entry *qe, *ret = NULL;
45 unsigned int key;
46 struct hlist_node *pos;
47 int rc;
48
49 key = ima_hash_key(digest_value);
50 rcu_read_lock();
51 hlist_for_each_entry_rcu(qe, pos, &ima_htable.queue[key], hnext) {
52 rc = memcmp(qe->entry->digest, digest_value, IMA_DIGEST_SIZE);
53 if (rc == 0) {
54 ret = qe;
55 break;
56 }
57 }
58 rcu_read_unlock();
59 return ret;
60 }
61
62 /* ima_add_template_entry helper function:
63 * - Add template entry to measurement list and hash table.
64 *
65 * (Called with ima_extend_list_mutex held.)
66 */
ima_add_digest_entry(struct ima_template_entry * entry)67 static int ima_add_digest_entry(struct ima_template_entry *entry)
68 {
69 struct ima_queue_entry *qe;
70 unsigned int key;
71
72 qe = kmalloc(sizeof(*qe), GFP_KERNEL);
73 if (qe == NULL) {
74 pr_err("IMA: OUT OF MEMORY ERROR creating queue entry.\n");
75 return -ENOMEM;
76 }
77 qe->entry = entry;
78
79 INIT_LIST_HEAD(&qe->later);
80 list_add_tail_rcu(&qe->later, &ima_measurements);
81
82 atomic_long_inc(&ima_htable.len);
83 key = ima_hash_key(entry->digest);
84 hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
85 return 0;
86 }
87
ima_pcr_extend(const u8 * hash)88 static int ima_pcr_extend(const u8 *hash)
89 {
90 int result = 0;
91
92 if (!ima_used_chip)
93 return result;
94
95 result = tpm_pcr_extend(TPM_ANY_NUM, CONFIG_IMA_MEASURE_PCR_IDX, hash);
96 if (result != 0)
97 pr_err("IMA: Error Communicating to TPM chip\n");
98 return result;
99 }
100
101 /* Add template entry to the measurement list and hash table,
102 * and extend the pcr.
103 */
ima_add_template_entry(struct ima_template_entry * entry,int violation,const char * op,struct inode * inode)104 int ima_add_template_entry(struct ima_template_entry *entry, int violation,
105 const char *op, struct inode *inode)
106 {
107 u8 digest[IMA_DIGEST_SIZE];
108 const char *audit_cause = "hash_added";
109 int audit_info = 1;
110 int result = 0;
111
112 mutex_lock(&ima_extend_list_mutex);
113 if (!violation) {
114 memcpy(digest, entry->digest, sizeof digest);
115 if (ima_lookup_digest_entry(digest)) {
116 audit_cause = "hash_exists";
117 goto out;
118 }
119 }
120
121 result = ima_add_digest_entry(entry);
122 if (result < 0) {
123 audit_cause = "ENOMEM";
124 audit_info = 0;
125 goto out;
126 }
127
128 if (violation) /* invalidate pcr */
129 memset(digest, 0xff, sizeof digest);
130
131 result = ima_pcr_extend(digest);
132 if (result != 0) {
133 audit_cause = "TPM error";
134 audit_info = 0;
135 }
136 out:
137 mutex_unlock(&ima_extend_list_mutex);
138 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
139 entry->template.file_name,
140 op, audit_cause, result, audit_info);
141 return result;
142 }
143