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 "ima.h"
24 
25 LIST_HEAD(ima_measurements);	/* list of all measurements */
26 
27 /* key: inode (before secure-hashing a file) */
28 struct 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  */
38 static DEFINE_MUTEX(ima_extend_list_mutex);
39 
40 /* lookup up the digest value in the hash table, and return the entry */
41 static 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  */
66 static 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 
87 static 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  */
103 int 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 	}
135 out:
136 	mutex_unlock(&ima_extend_list_mutex);
137 	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
138 			    entry->template.file_name,
139 			    op, audit_cause, result, audit_info);
140 	return result;
141 }
142