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
22 static struct key *keyring[INTEGRITY_KEYRING_MAX];
23
24 static 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
42 static 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
61 int 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
87 int 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
98 static 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
125 int __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
161 out:
162 ret = __integrity_init_keyring(id, perm, restriction);
163 if (ret)
164 kfree(restriction);
165 return ret;
166 }
167
168 static 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
194 int __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
218 int __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
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