summaryrefslogtreecommitdiffstats
path: root/security/integrity/ima/ima_queue_keys.c
blob: 93056c03bf5a23edd9431f61313ffa8ef986765a (plain)
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
// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2019 Microsoft Corporation
 *
 * Author: Lakshmi Ramasubramanian (nramas@linux.microsoft.com)
 *
 * File: ima_queue_keys.c
 *       Enables deferred processing of keys
 */

#include <linux/user_namespace.h>
#include <linux/workqueue.h>
#include <keys/asymmetric-type.h>
#include "ima.h"

/*
 * Flag to indicate whether a key can be processed
 * right away or should be queued for processing later.
 */
static bool ima_process_keys;

/*
 * To synchronize access to the list of keys that need to be measured
 */
static DEFINE_MUTEX(ima_keys_lock);
static LIST_HEAD(ima_keys);

/*
 * If custom IMA policy is not loaded then keys queued up
 * for measurement should be freed. This worker is used
 * for handling this scenario.
 */
static long ima_key_queue_timeout = 300000; /* 5 Minutes */
static void ima_keys_handler(struct work_struct *work);
static DECLARE_DELAYED_WORK(ima_keys_delayed_work, ima_keys_handler);
static bool timer_expired;

/*
 * This worker function frees keys that may still be
 * queued up in case custom IMA policy was not loaded.
 */
static void ima_keys_handler(struct work_struct *work)
{
	timer_expired = true;
	ima_process_queued_keys();
}

/*
 * This function sets up a worker to free queued keys in case
 * custom IMA policy was never loaded.
 */
void ima_init_key_queue(void)
{
	schedule_delayed_work(&ima_keys_delayed_work,
			      msecs_to_jiffies(ima_key_queue_timeout));
}

static void ima_free_key_entry(struct ima_key_entry *entry)
{
	if (entry) {
		kfree(entry->payload);
		kfree(entry->keyring_name);
		kfree(entry);
	}
}

static struct ima_key_entry *ima_alloc_key_entry(struct key *keyring,
						 const void *payload,
						 size_t payload_len)
{
	int rc = 0;
	const char *audit_cause = "ENOMEM";
	struct ima_key_entry *entry;

	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
	if (entry) {
		entry->payload = kmemdup(payload, payload_len, GFP_KERNEL);
		entry->keyring_name = kstrdup(keyring->description,
					      GFP_KERNEL);
		entry->payload_len = payload_len;
	}

	if ((entry == NULL) || (entry->payload == NULL) ||
	    (entry->keyring_name == NULL)) {
		rc = -ENOMEM;
		goto out;
	}

	INIT_LIST_HEAD(&entry->list);

out:
	if (rc) {
		integrity_audit_message(AUDIT_INTEGRITY_PCR, NULL,
					keyring->description,
					func_measure_str(KEY_CHECK),
					audit_cause, rc, 0, rc);
		ima_free_key_entry(entry);
		entry = NULL;
	}

	return entry;
}

bool ima_queue_key(struct key *keyring, const void *payload,
		   size_t payload_len)
{
	bool queued = false;
	struct ima_key_entry *entry;

	entry = ima_alloc_key_entry(keyring, payload, payload_len);
	if (!entry)
		return false;

	mutex_lock(&ima_keys_lock);
	if (!ima_process_keys) {
		list_add_tail(&entry->list, &ima_keys);
		queued = true;
	}
	mutex_unlock(&ima_keys_lock);

	if (!queued)
		ima_free_key_entry(entry);

	return queued;
}

/*
 * ima_process_queued_keys() - process keys queued for measurement
 *
 * This function sets ima_process_keys to true and processes queued keys.
 * From here on keys will be processed right away (not queued).
 */
void ima_process_queued_keys(void)
{
	struct ima_key_entry *entry, *tmp;
	bool process = false;

	if (ima_process_keys)
		return;

	/*
	 * Since ima_process_keys is set to true, any new key will be
	 * processed immediately and not be queued to ima_keys list.
	 * First one setting the ima_process_keys flag to true will
	 * process the queued keys.
	 */
	mutex_lock(&ima_keys_lock);
	if (!ima_process_keys) {
		ima_process_keys = true;
		process = true;
	}
	mutex_unlock(&ima_keys_lock);

	if (!process)
		return;

	if (!timer_expired)
		cancel_delayed_work_sync(&ima_keys_delayed_work);

	list_for_each_entry_safe(entry, tmp, &ima_keys, list) {
		if (!timer_expired)
			process_buffer_measurement(&init_user_ns, NULL,
						   entry->payload,
						   entry->payload_len,
						   entry->keyring_name,
						   KEY_CHECK, 0,
						   entry->keyring_name,
						   false, NULL, 0);
		list_del(&entry->list);
		ima_free_key_entry(entry);
	}
}

inline bool ima_should_queue_key(void)
{
	return !ima_process_keys;
}