1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2011 Intel Corporation
4 *
5 * Author:
6 * Dmitry Kasatkin <dmitry.kasatkin@intel.com>
7 */
8
9#include <linux/err.h>
10#include <linux/sched.h>
11#include <linux/slab.h>
12#include <linux/cred.h>
13#include <linux/kernel_read_file.h>
14#include <linux/key-type.h>
15#include <linux/digsig.h>
16#include <linux/vmalloc.h>
17#include <crypto/public_key.h>
18#include <keys/system_keyring.h>
19
20#include "integrity.h"
21
22static struct key *keyring[INTEGRITY_KEYRING_MAX];
23
24static const char * const keyring_name[INTEGRITY_KEYRING_MAX] = {
25#ifndef CONFIG_INTEGRITY_TRUSTED_KEYRING
26	"_evm",
27	"_ima",
28#else
29	".evm",
30	".ima",
31#endif
32	".platform",
33	".machine",
34};
35
36#ifdef CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
37#define restrict_link_to_ima restrict_link_by_digsig_builtin_and_secondary
38#else
39#define restrict_link_to_ima restrict_link_by_digsig_builtin
40#endif
41
42static struct key *integrity_keyring_from_id(const unsigned int id)
43{
44	if (id >= INTEGRITY_KEYRING_MAX)
45		return ERR_PTR(-EINVAL);
46
47	if (!keyring[id]) {
48		keyring[id] =
49			request_key(&key_type_keyring, keyring_name[id], NULL);
50		if (IS_ERR(keyring[id])) {
51			int err = PTR_ERR(keyring[id]);
52			pr_err("no %s keyring: %d\n", keyring_name[id], err);
53			keyring[id] = NULL;
54			return ERR_PTR(err);
55		}
56	}
57
58	return keyring[id];
59}
60
61int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
62			    const char *digest, int digestlen)
63{
64	struct key *keyring;
65
66	if (siglen < 2)
67		return -EINVAL;
68
69	keyring = integrity_keyring_from_id(id);
70	if (IS_ERR(keyring))
71		return PTR_ERR(keyring);
72
73	switch (sig[1]) {
74	case 1:
75		/* v1 API expect signature without xattr type */
76		return digsig_verify(keyring, sig + 1, siglen - 1, digest,
77				     digestlen);
78	case 2: /* regular file data hash based signature */
79	case 3: /* struct ima_file_id data based signature */
80		return asymmetric_verify(keyring, sig, siglen, digest,
81					 digestlen);
82	}
83
84	return -EOPNOTSUPP;
85}
86
87int integrity_modsig_verify(const unsigned int id, const struct modsig *modsig)
88{
89	struct key *keyring;
90
91	keyring = integrity_keyring_from_id(id);
92	if (IS_ERR(keyring))
93		return PTR_ERR(keyring);
94
95	return ima_modsig_verify(keyring, modsig);
96}
97
98static int __init __integrity_init_keyring(const unsigned int id,
99					   key_perm_t perm,
100					   struct key_restriction *restriction)
101{
102	const struct cred *cred = current_cred();
103	int err = 0;
104
105	keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
106				    KGIDT_INIT(0), cred, perm,
107				    KEY_ALLOC_NOT_IN_QUOTA, restriction, NULL);
108	if (IS_ERR(keyring[id])) {
109		err = PTR_ERR(keyring[id]);
110		pr_info("Can't allocate %s keyring (%d)\n",
111			keyring_name[id], err);
112		keyring[id] = NULL;
113	} else {
114		if (id == INTEGRITY_KEYRING_PLATFORM)
115			set_platform_trusted_keys(keyring[id]);
116		if (id == INTEGRITY_KEYRING_MACHINE && imputed_trust_enabled())
117			set_machine_trusted_keys(keyring[id]);
118		if (id == INTEGRITY_KEYRING_IMA)
119			load_module_cert(keyring[id]);
120	}
121
122	return err;
123}
124
125int __init integrity_init_keyring(const unsigned int id)
126{
127	struct key_restriction *restriction;
128	key_perm_t perm;
129	int ret;
130
131	perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW
132		| KEY_USR_READ | KEY_USR_SEARCH;
133
134	if (id == INTEGRITY_KEYRING_PLATFORM ||
135	    (id == INTEGRITY_KEYRING_MACHINE &&
136	    !IS_ENABLED(CONFIG_INTEGRITY_CA_MACHINE_KEYRING))) {
137		restriction = NULL;
138		goto out;
139	}
140
141	if (!IS_ENABLED(CONFIG_INTEGRITY_TRUSTED_KEYRING))
142		return 0;
143
144	restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
145	if (!restriction)
146		return -ENOMEM;
147
148	if (id == INTEGRITY_KEYRING_MACHINE)
149		restriction->check = restrict_link_by_ca;
150	else
151		restriction->check = restrict_link_to_ima;
152
153	/*
154	 * MOK keys can only be added through a read-only runtime services
155	 * UEFI variable during boot. No additional keys shall be allowed to
156	 * load into the machine keyring following init from userspace.
157	 */
158	if (id != INTEGRITY_KEYRING_MACHINE)
159		perm |= KEY_USR_WRITE;
160
161out:
162	ret = __integrity_init_keyring(id, perm, restriction);
163	if (ret)
164		kfree(restriction);
165	return ret;
166}
167
168static int __init integrity_add_key(const unsigned int id, const void *data,
169				    off_t size, key_perm_t perm)
170{
171	key_ref_t key;
172	int rc = 0;
173
174	if (!keyring[id])
175		return -EINVAL;
176
177	key = key_create_or_update(make_key_ref(keyring[id], 1), "asymmetric",
178				   NULL, data, size, perm,
179				   KEY_ALLOC_NOT_IN_QUOTA);
180	if (IS_ERR(key)) {
181		rc = PTR_ERR(key);
182		if (id != INTEGRITY_KEYRING_MACHINE)
183			pr_err("Problem loading X.509 certificate %d\n", rc);
184	} else {
185		pr_notice("Loaded X.509 cert '%s'\n",
186			  key_ref_to_ptr(key)->description);
187		key_ref_put(key);
188	}
189
190	return rc;
191
192}
193
194int __init integrity_load_x509(const unsigned int id, const char *path)
195{
196	void *data = NULL;
197	size_t size;
198	int rc;
199	key_perm_t perm;
200
201	rc = kernel_read_file_from_path(path, 0, &data, INT_MAX, NULL,
202					READING_X509_CERTIFICATE);
203	if (rc < 0) {
204		pr_err("Unable to open file: %s (%d)", path, rc);
205		return rc;
206	}
207	size = rc;
208
209	perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW | KEY_USR_READ;
210
211	pr_info("Loading X.509 certificate: %s\n", path);
212	rc = integrity_add_key(id, (const void *)data, size, perm);
213
214	vfree(data);
215	return rc;
216}
217
218int __init integrity_load_cert(const unsigned int id, const char *source,
219			       const void *data, size_t len, key_perm_t perm)
220{
221	if (!data)
222		return -EINVAL;
223
224	pr_info("Loading X.509 certificate: %s\n", source);
225	return integrity_add_key(id, data, len, perm);
226}
227