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3323eec9 MZ |
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 | */ | |
20ee451f JP |
21 | |
22 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
23 | ||
3323eec9 MZ |
24 | #include <linux/module.h> |
25 | #include <linux/rculist.h> | |
5a0e3ad6 | 26 | #include <linux/slab.h> |
3323eec9 MZ |
27 | #include "ima.h" |
28 | ||
7b7e5916 RS |
29 | #define AUDIT_CAUSE_LEN_MAX 32 |
30 | ||
3323eec9 MZ |
31 | LIST_HEAD(ima_measurements); /* list of all measurements */ |
32 | ||
33 | /* key: inode (before secure-hashing a file) */ | |
34 | struct ima_h_table ima_htable = { | |
35 | .len = ATOMIC_LONG_INIT(0), | |
36 | .violations = ATOMIC_LONG_INIT(0), | |
37 | .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT | |
38 | }; | |
39 | ||
40 | /* mutex protects atomicity of extending measurement list | |
41 | * and extending the TPM PCR aggregate. Since tpm_extend can take | |
42 | * long (and the tpm driver uses a mutex), we can't use the spinlock. | |
43 | */ | |
44 | static DEFINE_MUTEX(ima_extend_list_mutex); | |
45 | ||
46 | /* lookup up the digest value in the hash table, and return the entry */ | |
67696f6d ER |
47 | static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value, |
48 | int pcr) | |
3323eec9 MZ |
49 | { |
50 | struct ima_queue_entry *qe, *ret = NULL; | |
51 | unsigned int key; | |
3323eec9 MZ |
52 | int rc; |
53 | ||
54 | key = ima_hash_key(digest_value); | |
55 | rcu_read_lock(); | |
b67bfe0d | 56 | hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) { |
140d8022 | 57 | rc = memcmp(qe->entry->digest, digest_value, TPM_DIGEST_SIZE); |
67696f6d | 58 | if ((rc == 0) && (qe->entry->pcr == pcr)) { |
3323eec9 MZ |
59 | ret = qe; |
60 | break; | |
61 | } | |
62 | } | |
63 | rcu_read_unlock(); | |
64 | return ret; | |
65 | } | |
66 | ||
67 | /* ima_add_template_entry helper function: | |
dcfc5693 MZ |
68 | * - Add template entry to the measurement list and hash table, for |
69 | * all entries except those carried across kexec. | |
3323eec9 MZ |
70 | * |
71 | * (Called with ima_extend_list_mutex held.) | |
72 | */ | |
dcfc5693 MZ |
73 | static int ima_add_digest_entry(struct ima_template_entry *entry, |
74 | bool update_htable) | |
3323eec9 MZ |
75 | { |
76 | struct ima_queue_entry *qe; | |
77 | unsigned int key; | |
78 | ||
79 | qe = kmalloc(sizeof(*qe), GFP_KERNEL); | |
80 | if (qe == NULL) { | |
20ee451f | 81 | pr_err("OUT OF MEMORY ERROR creating queue entry\n"); |
3323eec9 MZ |
82 | return -ENOMEM; |
83 | } | |
84 | qe->entry = entry; | |
85 | ||
86 | INIT_LIST_HEAD(&qe->later); | |
87 | list_add_tail_rcu(&qe->later, &ima_measurements); | |
88 | ||
89 | atomic_long_inc(&ima_htable.len); | |
dcfc5693 MZ |
90 | if (update_htable) { |
91 | key = ima_hash_key(entry->digest); | |
92 | hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]); | |
93 | } | |
3323eec9 MZ |
94 | return 0; |
95 | } | |
96 | ||
544e1cea | 97 | static int ima_pcr_extend(const u8 *hash, int pcr) |
3323eec9 MZ |
98 | { |
99 | int result = 0; | |
100 | ||
101 | if (!ima_used_chip) | |
102 | return result; | |
103 | ||
544e1cea | 104 | result = tpm_pcr_extend(TPM_ANY_NUM, pcr, hash); |
3323eec9 | 105 | if (result != 0) |
20ee451f | 106 | pr_err("Error Communicating to TPM chip, result: %d\n", result); |
3323eec9 MZ |
107 | return result; |
108 | } | |
109 | ||
110 | /* Add template entry to the measurement list and hash table, | |
111 | * and extend the pcr. | |
112 | */ | |
113 | int ima_add_template_entry(struct ima_template_entry *entry, int violation, | |
9803d413 RS |
114 | const char *op, struct inode *inode, |
115 | const unsigned char *filename) | |
3323eec9 | 116 | { |
140d8022 | 117 | u8 digest[TPM_DIGEST_SIZE]; |
3323eec9 | 118 | const char *audit_cause = "hash_added"; |
7b7e5916 | 119 | char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX]; |
3323eec9 | 120 | int audit_info = 1; |
7b7e5916 | 121 | int result = 0, tpmresult = 0; |
3323eec9 MZ |
122 | |
123 | mutex_lock(&ima_extend_list_mutex); | |
124 | if (!violation) { | |
2bb930ab | 125 | memcpy(digest, entry->digest, sizeof(digest)); |
67696f6d | 126 | if (ima_lookup_digest_entry(digest, entry->pcr)) { |
3323eec9 | 127 | audit_cause = "hash_exists"; |
45fae749 | 128 | result = -EEXIST; |
3323eec9 MZ |
129 | goto out; |
130 | } | |
131 | } | |
132 | ||
dcfc5693 | 133 | result = ima_add_digest_entry(entry, 1); |
3323eec9 MZ |
134 | if (result < 0) { |
135 | audit_cause = "ENOMEM"; | |
136 | audit_info = 0; | |
137 | goto out; | |
138 | } | |
139 | ||
140 | if (violation) /* invalidate pcr */ | |
2bb930ab | 141 | memset(digest, 0xff, sizeof(digest)); |
3323eec9 | 142 | |
544e1cea | 143 | tpmresult = ima_pcr_extend(digest, entry->pcr); |
7b7e5916 RS |
144 | if (tpmresult != 0) { |
145 | snprintf(tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, "TPM_error(%d)", | |
146 | tpmresult); | |
147 | audit_cause = tpm_audit_cause; | |
3323eec9 MZ |
148 | audit_info = 0; |
149 | } | |
150 | out: | |
151 | mutex_unlock(&ima_extend_list_mutex); | |
9803d413 | 152 | integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename, |
3323eec9 MZ |
153 | op, audit_cause, result, audit_info); |
154 | return result; | |
155 | } | |
94c3aac5 MZ |
156 | |
157 | int ima_restore_measurement_entry(struct ima_template_entry *entry) | |
158 | { | |
159 | int result = 0; | |
160 | ||
161 | mutex_lock(&ima_extend_list_mutex); | |
dcfc5693 | 162 | result = ima_add_digest_entry(entry, 0); |
94c3aac5 MZ |
163 | mutex_unlock(&ima_extend_list_mutex); |
164 | return result; | |
165 | } |