1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
|
/*
* Copyright (C) 2005,2006,2007,2008 IBM Corporation
*
* Authors:
* Serge Hallyn <serue@us.ibm.com>
* Reiner Sailer <sailer@watson.ibm.com>
* Mimi Zohar <zohar@us.ibm.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation, version 2 of the
* License.
*
* File: ima_queue.c
* Implements queues that store template measurements and
* maintains aggregate over the stored measurements
* in the pre-configured TPM PCR (if available).
* The measurement list is append-only. No entry is
* ever removed or changed during the boot-cycle.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/rculist.h>
#include <linux/slab.h>
#include "ima.h"
#define AUDIT_CAUSE_LEN_MAX 32
LIST_HEAD(ima_measurements); /* list of all measurements */
#ifdef CONFIG_IMA_KEXEC
static unsigned long binary_runtime_size;
#else
static unsigned long binary_runtime_size = ULONG_MAX;
#endif
/* key: inode (before secure-hashing a file) */
struct ima_h_table ima_htable = {
.len = ATOMIC_LONG_INIT(0),
.violations = ATOMIC_LONG_INIT(0),
.queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT
};
/* mutex protects atomicity of extending measurement list
* and extending the TPM PCR aggregate. Since tpm_extend can take
* long (and the tpm driver uses a mutex), we can't use the spinlock.
*/
static DEFINE_MUTEX(ima_extend_list_mutex);
/* lookup up the digest value in the hash table, and return the entry */
static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value,
int pcr)
{
struct ima_queue_entry *qe, *ret = NULL;
unsigned int key;
int rc;
key = ima_hash_key(digest_value);
rcu_read_lock();
hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) {
rc = memcmp(qe->entry->digest, digest_value, TPM_DIGEST_SIZE);
if ((rc == 0) && (qe->entry->pcr == pcr)) {
ret = qe;
break;
}
}
rcu_read_unlock();
return ret;
}
/*
* Calculate the memory required for serializing a single
* binary_runtime_measurement list entry, which contains a
* couple of variable length fields (e.g template name and data).
*/
static int get_binary_runtime_size(struct ima_template_entry *entry)
{
int size = 0;
size += sizeof(u32); /* pcr */
size += sizeof(entry->digest);
size += sizeof(int); /* template name size field */
size += strlen(entry->template_desc->name);
size += sizeof(entry->template_data_len);
size += entry->template_data_len;
return size;
}
/* ima_add_template_entry helper function:
* - Add template entry to the measurement list and hash table, for
* all entries except those carried across kexec.
*
* (Called with ima_extend_list_mutex held.)
*/
static int ima_add_digest_entry(struct ima_template_entry *entry,
bool update_htable)
{
struct ima_queue_entry *qe;
unsigned int key;
qe = kmalloc(sizeof(*qe), GFP_KERNEL);
if (qe == NULL) {
pr_err("OUT OF MEMORY ERROR creating queue entry\n");
return -ENOMEM;
}
qe->entry = entry;
INIT_LIST_HEAD(&qe->later);
list_add_tail_rcu(&qe->later, &ima_measurements);
atomic_long_inc(&ima_htable.len);
if (update_htable) {
key = ima_hash_key(entry->digest);
hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
}
if (binary_runtime_size != ULONG_MAX) {
int size;
size = get_binary_runtime_size(entry);
binary_runtime_size = (binary_runtime_size < ULONG_MAX - size) ?
binary_runtime_size + size : ULONG_MAX;
}
return 0;
}
/*
* Return the amount of memory required for serializing the
* entire binary_runtime_measurement list, including the ima_kexec_hdr
* structure.
*/
unsigned long ima_get_binary_runtime_size(void)
{
if (binary_runtime_size >= (ULONG_MAX - sizeof(struct ima_kexec_hdr)))
return ULONG_MAX;
else
return binary_runtime_size + sizeof(struct ima_kexec_hdr);
};
static int ima_pcr_extend(const u8 *hash, int pcr)
{
int result = 0;
if (!ima_used_chip)
return result;
result = tpm_pcr_extend(TPM_ANY_NUM, pcr, hash);
if (result != 0)
pr_err("Error Communicating to TPM chip, result: %d\n", result);
return result;
}
/*
* Add template entry to the measurement list and hash table, and
* extend the pcr.
*
* On systems which support carrying the IMA measurement list across
* kexec, maintain the total memory size required for serializing the
* binary_runtime_measurements.
*/
int ima_add_template_entry(struct ima_template_entry *entry, int violation,
const char *op, struct inode *inode,
const unsigned char *filename)
{
u8 digest[TPM_DIGEST_SIZE];
const char *audit_cause = "hash_added";
char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX];
int audit_info = 1;
int result = 0, tpmresult = 0;
mutex_lock(&ima_extend_list_mutex);
if (!violation) {
memcpy(digest, entry->digest, sizeof(digest));
if (ima_lookup_digest_entry(digest, entry->pcr)) {
audit_cause = "hash_exists";
result = -EEXIST;
goto out;
}
}
result = ima_add_digest_entry(entry, 1);
if (result < 0) {
audit_cause = "ENOMEM";
audit_info = 0;
goto out;
}
if (violation) /* invalidate pcr */
memset(digest, 0xff, sizeof(digest));
tpmresult = ima_pcr_extend(digest, entry->pcr);
if (tpmresult != 0) {
snprintf(tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, "TPM_error(%d)",
tpmresult);
audit_cause = tpm_audit_cause;
audit_info = 0;
}
out:
mutex_unlock(&ima_extend_list_mutex);
integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
op, audit_cause, result, audit_info);
return result;
}
int ima_restore_measurement_entry(struct ima_template_entry *entry)
{
int result = 0;
mutex_lock(&ima_extend_list_mutex);
result = ima_add_digest_entry(entry, 0);
mutex_unlock(&ima_extend_list_mutex);
return result;
}
|
