summaryrefslogtreecommitdiff
path: root/security/integrity/ima/ima_template.c
blob: 0b7404ebfa80baf9a3741fa36f74aca5548f8405 (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
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
/*
 * Copyright (C) 2013 Politecnico di Torino, Italy
 *                    TORSEC group -- http://security.polito.it
 *
 * Author: Roberto Sassu <roberto.sassu@polito.it>
 *
 * 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_template.c
 *      Helpers to manage template descriptors.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <crypto/hash_info.h>

#include "ima.h"
#include "ima_template_lib.h"

static struct ima_template_desc defined_templates[] = {
	{.name = IMA_TEMPLATE_IMA_NAME, .fmt = IMA_TEMPLATE_IMA_FMT},
	{.name = "ima-ng", .fmt = "d-ng|n-ng"},
	{.name = "ima-sig", .fmt = "d-ng|n-ng|sig"},
	{.name = "", .fmt = ""},	/* placeholder for a custom format */
};

static struct ima_template_field supported_fields[] = {
	{.field_id = "d", .field_init = ima_eventdigest_init,
	 .field_show = ima_show_template_digest},
	{.field_id = "n", .field_init = ima_eventname_init,
	 .field_show = ima_show_template_string},
	{.field_id = "d-ng", .field_init = ima_eventdigest_ng_init,
	 .field_show = ima_show_template_digest_ng},
	{.field_id = "n-ng", .field_init = ima_eventname_ng_init,
	 .field_show = ima_show_template_string},
	{.field_id = "sig", .field_init = ima_eventsig_init,
	 .field_show = ima_show_template_sig},
};

static struct ima_template_desc *ima_template;
static struct ima_template_desc *lookup_template_desc(const char *name);
static int template_desc_init_fields(const char *template_fmt,
				     struct ima_template_field ***fields,
				     int *num_fields);

static int __init ima_template_setup(char *str)
{
	struct ima_template_desc *template_desc;
	int template_len = strlen(str);

	if (ima_template)
		return 1;

	/*
	 * Verify that a template with the supplied name exists.
	 * If not, use CONFIG_IMA_DEFAULT_TEMPLATE.
	 */
	template_desc = lookup_template_desc(str);
	if (!template_desc) {
		pr_err("template %s not found, using %s\n",
		       str, CONFIG_IMA_DEFAULT_TEMPLATE);
		return 1;
	}

	/*
	 * Verify whether the current hash algorithm is supported
	 * by the 'ima' template.
	 */
	if (template_len == 3 && strcmp(str, IMA_TEMPLATE_IMA_NAME) == 0 &&
	    ima_hash_algo != HASH_ALGO_SHA1 && ima_hash_algo != HASH_ALGO_MD5) {
		pr_err("template does not support hash alg\n");
		return 1;
	}

	ima_template = template_desc;
	return 1;
}
__setup("ima_template=", ima_template_setup);

static int __init ima_template_fmt_setup(char *str)
{
	int num_templates = ARRAY_SIZE(defined_templates);

	if (ima_template)
		return 1;

	if (template_desc_init_fields(str, NULL, NULL) < 0) {
		pr_err("format string '%s' not valid, using template %s\n",
		       str, CONFIG_IMA_DEFAULT_TEMPLATE);
		return 1;
	}

	defined_templates[num_templates - 1].fmt = str;
	ima_template = defined_templates + num_templates - 1;
	return 1;
}
__setup("ima_template_fmt=", ima_template_fmt_setup);

static struct ima_template_desc *lookup_template_desc(const char *name)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(defined_templates); i++) {
		if (strcmp(defined_templates[i].name, name) == 0)
			return defined_templates + i;
	}

	return NULL;
}

static struct ima_template_field *lookup_template_field(const char *field_id)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(supported_fields); i++)
		if (strncmp(supported_fields[i].field_id, field_id,
			    IMA_TEMPLATE_FIELD_ID_MAX_LEN) == 0)
			return &supported_fields[i];
	return NULL;
}

static int template_fmt_size(const char *template_fmt)
{
	char c;
	int template_fmt_len = strlen(template_fmt);
	int i = 0, j = 0;

	while (i < template_fmt_len) {
		c = template_fmt[i];
		if (c == '|')
			j++;
		i++;
	}

	return j + 1;
}

static int template_desc_init_fields(const char *template_fmt,
				     struct ima_template_field ***fields,
				     int *num_fields)
{
	const char *template_fmt_ptr;
	struct ima_template_field *found_fields[IMA_TEMPLATE_NUM_FIELDS_MAX];
	int template_num_fields = template_fmt_size(template_fmt);
	int i, len;

	if (template_num_fields > IMA_TEMPLATE_NUM_FIELDS_MAX) {
		pr_err("format string '%s' contains too many fields\n",
		       template_fmt);
		return -EINVAL;
	}

	for (i = 0, template_fmt_ptr = template_fmt; i < template_num_fields;
	     i++, template_fmt_ptr += len + 1) {
		char tmp_field_id[IMA_TEMPLATE_FIELD_ID_MAX_LEN + 1];

		len = strchrnul(template_fmt_ptr, '|') - template_fmt_ptr;
		if (len == 0 || len > IMA_TEMPLATE_FIELD_ID_MAX_LEN) {
			pr_err("Invalid field with length %d\n", len);
			return -EINVAL;
		}

		memcpy(tmp_field_id, template_fmt_ptr, len);
		tmp_field_id[len] = '\0';
		found_fields[i] = lookup_template_field(tmp_field_id);
		if (!found_fields[i]) {
			pr_err("field '%s' not found\n", tmp_field_id);
			return -ENOENT;
		}
	}

	if (fields && num_fields) {
		*fields = kmalloc_array(i, sizeof(*fields), GFP_KERNEL);
		if (*fields == NULL)
			return -ENOMEM;

		memcpy(*fields, found_fields, i * sizeof(*fields));
		*num_fields = i;
	}

	return 0;
}

struct ima_template_desc *ima_template_desc_current(void)
{
	if (!ima_template)
		ima_template =
		    lookup_template_desc(CONFIG_IMA_DEFAULT_TEMPLATE);
	return ima_template;
}

int __init ima_init_template(void)
{
	struct ima_template_desc *template = ima_template_desc_current();
	int result;

	result = template_desc_init_fields(template->fmt,
					   &(template->fields),
					   &(template->num_fields));
	if (result < 0)
		pr_err("template %s init failed, result: %d\n",
		       (strlen(template->name) ?
		       template->name : template->fmt), result);

	return result;
}