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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2011 Intel Corporation
4 *
5 * Author:
6 * Dmitry Kasatkin <[email protected]>
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, u8 algo)
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 return asymmetric_verify(keyring, sig, siglen, digest,
80 digestlen);
81 case 3: /* struct ima_file_id data based signature */
82 return asymmetric_verify_v3(keyring, sig, siglen, digest,
83 digestlen, algo);
84 }
85
86 return -EOPNOTSUPP;
87}
88
89int integrity_modsig_verify(const unsigned int id, const struct modsig *modsig)
90{
91 struct key *keyring;
92
93 keyring = integrity_keyring_from_id(id);
94 if (IS_ERR(keyring))
95 return PTR_ERR(keyring);
96
97 return ima_modsig_verify(keyring, modsig);
98}
99
100static int __init __integrity_init_keyring(const unsigned int id,
101 key_perm_t perm,
102 struct key_restriction *restriction)
103{
104 const struct cred *cred = current_cred();
105 int err = 0;
106
107 keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
108 KGIDT_INIT(0), cred, perm,
109 KEY_ALLOC_NOT_IN_QUOTA, restriction, NULL);
110 if (IS_ERR(keyring[id])) {
111 err = PTR_ERR(keyring[id]);
112 pr_info("Can't allocate %s keyring (%d)\n",
113 keyring_name[id], err);
114 keyring[id] = NULL;
115 } else {
116 if (id == INTEGRITY_KEYRING_PLATFORM)
117 set_platform_trusted_keys(keyring[id]);
118 if (id == INTEGRITY_KEYRING_MACHINE && imputed_trust_enabled())
119 set_machine_trusted_keys(keyring[id]);
120 if (id == INTEGRITY_KEYRING_IMA)
121 load_module_cert(keyring[id]);
122 }
123
124 return err;
125}
126
127int __init integrity_init_keyring(const unsigned int id)
128{
129 struct key_restriction *restriction;
130 key_perm_t perm;
131 int ret;
132
133 perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW
134 | KEY_USR_READ | KEY_USR_SEARCH;
135
136 if (id == INTEGRITY_KEYRING_PLATFORM ||
137 (id == INTEGRITY_KEYRING_MACHINE &&
138 !IS_ENABLED(CONFIG_INTEGRITY_CA_MACHINE_KEYRING))) {
139 restriction = NULL;
140 goto out;
141 }
142
143 if (!IS_ENABLED(CONFIG_INTEGRITY_TRUSTED_KEYRING))
144 return 0;
145
146 restriction = kzalloc_obj(struct key_restriction);
147 if (!restriction)
148 return -ENOMEM;
149
150 if (id == INTEGRITY_KEYRING_MACHINE)
151 restriction->check = restrict_link_by_ca;
152 else
153 restriction->check = restrict_link_to_ima;
154
155 /*
156 * MOK keys can only be added through a read-only runtime services
157 * UEFI variable during boot. No additional keys shall be allowed to
158 * load into the machine keyring following init from userspace.
159 */
160 if (id != INTEGRITY_KEYRING_MACHINE)
161 perm |= KEY_USR_WRITE;
162
163out:
164 ret = __integrity_init_keyring(id, perm, restriction);
165 if (ret)
166 kfree(restriction);
167 return ret;
168}
169
170static int __init integrity_add_key(const unsigned int id, const void *data,
171 off_t size, key_perm_t perm)
172{
173 key_ref_t key;
174 int rc = 0;
175
176 if (!keyring[id])
177 return -EINVAL;
178
179 key = key_create_or_update(make_key_ref(keyring[id], 1), "asymmetric",
180 NULL, data, size, perm,
181 KEY_ALLOC_NOT_IN_QUOTA);
182 if (IS_ERR(key)) {
183 rc = PTR_ERR(key);
184 if (id != INTEGRITY_KEYRING_MACHINE)
185 pr_err("Problem loading X.509 certificate %d\n", rc);
186 } else {
187 pr_notice("Loaded X.509 cert '%s'\n",
188 key_ref_to_ptr(key)->description);
189 key_ref_put(key);
190 }
191
192 return rc;
193
194}
195
196int __init integrity_load_x509(const unsigned int id, const char *path)
197{
198 void *data = NULL;
199 size_t size;
200 int rc;
201 key_perm_t perm;
202
203 rc = kernel_read_file_from_path(path, 0, &data, INT_MAX, NULL,
204 READING_X509_CERTIFICATE);
205 if (rc < 0) {
206 pr_err("Unable to open file: %s (%d)", path, rc);
207 return rc;
208 }
209 size = rc;
210
211 perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW | KEY_USR_READ;
212
213 pr_info("Loading X.509 certificate: %s\n", path);
214 rc = integrity_add_key(id, (const void *)data, size, perm);
215
216 vfree(data);
217 return rc;
218}
219
220int __init integrity_load_cert(const unsigned int id, const char *source,
221 const void *data, size_t len, key_perm_t perm)
222{
223 if (!data)
224 return -EINVAL;
225
226 pr_info("Loading X.509 certificate: %s\n", source);
227 return integrity_add_key(id, data, len, perm);
228}