summaryrefslogtreecommitdiffstats
path: root/security/integrity/digsig.c
blob: 5eacba858e4be266f9828b6c17dce46691025fd0 (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
/*
 * Copyright (C) 2011 Intel Corporation
 *
 * Author:
 * Dmitry Kasatkin <dmitry.kasatkin@intel.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.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/err.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/cred.h>
#include <linux/key-type.h>
#include <linux/digsig.h>
#include <linux/vmalloc.h>
#include <crypto/public_key.h>
#include <keys/system_keyring.h>

#include "integrity.h"

static struct key *keyring[INTEGRITY_KEYRING_MAX];

static const char * const keyring_name[INTEGRITY_KEYRING_MAX] = {
#ifndef CONFIG_INTEGRITY_TRUSTED_KEYRING
	"_evm",
	"_ima",
#else
	".evm",
	".ima",
#endif
	"_module",
};

#ifdef CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
#define restrict_link_to_ima restrict_link_by_builtin_and_secondary_trusted
#else
#define restrict_link_to_ima restrict_link_by_builtin_trusted
#endif

int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
			    const char *digest, int digestlen)
{
	if (id >= INTEGRITY_KEYRING_MAX || siglen < 2)
		return -EINVAL;

	if (!keyring[id]) {
		keyring[id] =
			request_key(&key_type_keyring, keyring_name[id], NULL);
		if (IS_ERR(keyring[id])) {
			int err = PTR_ERR(keyring[id]);
			pr_err("no %s keyring: %d\n", keyring_name[id], err);
			keyring[id] = NULL;
			return err;
		}
	}

	switch (sig[1]) {
	case 1:
		/* v1 API expect signature without xattr type */
		return digsig_verify(keyring[id], sig + 1, siglen - 1,
				     digest, digestlen);
	case 2:
		return asymmetric_verify(keyring[id], sig, siglen,
					 digest, digestlen);
	}

	return -EOPNOTSUPP;
}

int __init integrity_init_keyring(const unsigned int id)
{
	const struct cred *cred = current_cred();
	struct key_restriction *restriction;
	int err = 0;

	if (!IS_ENABLED(CONFIG_INTEGRITY_TRUSTED_KEYRING))
		return 0;

	restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
	if (!restriction)
		return -ENOMEM;

	restriction->check = restrict_link_to_ima;

	keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
				    KGIDT_INIT(0), cred,
				    ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
				     KEY_USR_VIEW | KEY_USR_READ |
				     KEY_USR_WRITE | KEY_USR_SEARCH),
				    KEY_ALLOC_NOT_IN_QUOTA,
				    restriction, NULL);
	if (IS_ERR(keyring[id])) {
		err = PTR_ERR(keyring[id]);
		pr_info("Can't allocate %s keyring (%d)\n",
			keyring_name[id], err);
		keyring[id] = NULL;
	}
	return err;
}

int __init integrity_load_x509(const unsigned int id, const char *path)
{
	key_ref_t key;
	void *data;
	loff_t size;
	int rc;

	if (!keyring[id])
		return -EINVAL;

	rc = kernel_read_file_from_path(path, &data, &size, 0,
					READING_X509_CERTIFICATE);
	if (rc < 0) {
		pr_err("Unable to open file: %s (%d)", path, rc);
		return rc;
	}

	key = key_create_or_update(make_key_ref(keyring[id], 1),
				   "asymmetric",
				   NULL,
				   data,
				   size,
				   ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
				    KEY_USR_VIEW | KEY_USR_READ),
				   KEY_ALLOC_NOT_IN_QUOTA);
	if (IS_ERR(key)) {
		rc = PTR_ERR(key);
		pr_err("Problem loading X.509 certificate (%d): %s\n",
		       rc, path);
	} else {
		pr_notice("Loaded X.509 cert '%s': %s\n",
			  key_ref_to_ptr(key)->description, path);
		key_ref_put(key);
	}
	vfree(data);
	return 0;
}