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 #define AUDIT_CAUSE_LEN_MAX 32
27
28 LIST_HEAD(ima_measurements); /* list of all measurements */
29
30 /* key: inode (before secure-hashing a file) */
31 struct ima_h_table ima_htable = {
32 .len = ATOMIC_LONG_INIT(0),
33 .violations = ATOMIC_LONG_INIT(0),
34 .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT
35 };
36
37 /* mutex protects atomicity of extending measurement list
38 * and extending the TPM PCR aggregate. Since tpm_extend can take
39 * long (and the tpm driver uses a mutex), we can't use the spinlock.
40 */
41 static DEFINE_MUTEX(ima_extend_list_mutex);
42
43 /* lookup up the digest value in the hash table, and return the entry */
ima_lookup_digest_entry(u8 * digest_value)44 static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value)
45 {
46 struct ima_queue_entry *qe, *ret = NULL;
47 unsigned int key;
48 int rc;
49
50 key = ima_hash_key(digest_value);
51 rcu_read_lock();
52 hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) {
53 rc = memcmp(qe->entry->digest, digest_value, IMA_DIGEST_SIZE);
54 if (rc == 0) {
55 ret = qe;
56 break;
57 }
58 }
59 rcu_read_unlock();
60 return ret;
61 }
62
63 /* ima_add_template_entry helper function:
64 * - Add template entry to measurement list and hash table.
65 *
66 * (Called with ima_extend_list_mutex held.)
67 */
ima_add_digest_entry(struct ima_template_entry * entry)68 static int ima_add_digest_entry(struct ima_template_entry *entry)
69 {
70 struct ima_queue_entry *qe;
71 unsigned int key;
72
73 qe = kmalloc(sizeof(*qe), GFP_KERNEL);
74 if (qe == NULL) {
75 pr_err("IMA: OUT OF MEMORY ERROR creating queue entry.\n");
76 return -ENOMEM;
77 }
78 qe->entry = entry;
79
80 INIT_LIST_HEAD(&qe->later);
81 list_add_tail_rcu(&qe->later, &ima_measurements);
82
83 atomic_long_inc(&ima_htable.len);
84 key = ima_hash_key(entry->digest);
85 hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
86 return 0;
87 }
88
ima_pcr_extend(const u8 * hash)89 static int ima_pcr_extend(const u8 *hash)
90 {
91 int result = 0;
92
93 if (!ima_used_chip)
94 return result;
95
96 result = tpm_pcr_extend(TPM_ANY_NUM, CONFIG_IMA_MEASURE_PCR_IDX, hash);
97 if (result != 0)
98 pr_err("IMA: Error Communicating to TPM chip, result: %d\n",
99 result);
100 return result;
101 }
102
103 /* Add template entry to the measurement list and hash table,
104 * and extend the pcr.
105 */
ima_add_template_entry(struct ima_template_entry * entry,int violation,const char * op,struct inode * inode)106 int ima_add_template_entry(struct ima_template_entry *entry, int violation,
107 const char *op, struct inode *inode)
108 {
109 u8 digest[IMA_DIGEST_SIZE];
110 const char *audit_cause = "hash_added";
111 char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX];
112 int audit_info = 1;
113 int result = 0, tpmresult = 0;
114
115 mutex_lock(&ima_extend_list_mutex);
116 if (!violation) {
117 memcpy(digest, entry->digest, sizeof digest);
118 if (ima_lookup_digest_entry(digest)) {
119 audit_cause = "hash_exists";
120 result = -EEXIST;
121 goto out;
122 }
123 }
124
125 result = ima_add_digest_entry(entry);
126 if (result < 0) {
127 audit_cause = "ENOMEM";
128 audit_info = 0;
129 goto out;
130 }
131
132 if (violation) /* invalidate pcr */
133 memset(digest, 0xff, sizeof digest);
134
135 tpmresult = ima_pcr_extend(digest);
136 if (tpmresult != 0) {
137 snprintf(tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, "TPM_error(%d)",
138 tpmresult);
139 audit_cause = tpm_audit_cause;
140 audit_info = 0;
141 }
142 out:
143 mutex_unlock(&ima_extend_list_mutex);
144 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
145 entry->template.file_name,
146 op, audit_cause, result, audit_info);
147 return result;
148 }
149