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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); | |
79b854c5 MZ |
137 | integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, |
138 | entry->template.file_name, | |
3323eec9 MZ |
139 | op, audit_cause, result, audit_info); |
140 | return result; | |
141 | } |