1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2010 IBM Corporation
4 * Copyright (c) 2019-2021, Linaro Limited
5 *
6 * See Documentation/security/keys/trusted-encrypted.rst
7 */
8
9 #include <keys/user-type.h>
10 #include <keys/trusted-type.h>
11 #include <keys/trusted_tee.h>
12 #include <keys/trusted_caam.h>
13 #include <keys/trusted_tpm.h>
14 #include <linux/capability.h>
15 #include <linux/err.h>
16 #include <linux/init.h>
17 #include <linux/key-type.h>
18 #include <linux/module.h>
19 #include <linux/parser.h>
20 #include <linux/random.h>
21 #include <linux/rcupdate.h>
22 #include <linux/slab.h>
23 #include <linux/static_call.h>
24 #include <linux/string.h>
25 #include <linux/uaccess.h>
26
27 static char *trusted_rng = "default";
28 module_param_named(rng, trusted_rng, charp, 0);
29 MODULE_PARM_DESC(rng, "Select trusted key RNG");
30
31 static char *trusted_key_source;
32 module_param_named(source, trusted_key_source, charp, 0);
33 MODULE_PARM_DESC(source, "Select trusted keys source (tpm, tee or caam)");
34
35 static const struct trusted_key_source trusted_key_sources[] = {
36 #if defined(CONFIG_TRUSTED_KEYS_TPM)
37 { "tpm", &trusted_key_tpm_ops },
38 #endif
39 #if defined(CONFIG_TRUSTED_KEYS_TEE)
40 { "tee", &trusted_key_tee_ops },
41 #endif
42 #if defined(CONFIG_TRUSTED_KEYS_CAAM)
43 { "caam", &trusted_key_caam_ops },
44 #endif
45 };
46
47 DEFINE_STATIC_CALL_NULL(trusted_key_init, *trusted_key_sources[0].ops->init);
48 DEFINE_STATIC_CALL_NULL(trusted_key_seal, *trusted_key_sources[0].ops->seal);
49 DEFINE_STATIC_CALL_NULL(trusted_key_unseal,
50 *trusted_key_sources[0].ops->unseal);
51 DEFINE_STATIC_CALL_NULL(trusted_key_get_random,
52 *trusted_key_sources[0].ops->get_random);
53 DEFINE_STATIC_CALL_NULL(trusted_key_exit, *trusted_key_sources[0].ops->exit);
54 static unsigned char migratable;
55
56 enum {
57 Opt_err,
58 Opt_new, Opt_load, Opt_update,
59 };
60
61 static const match_table_t key_tokens = {
62 {Opt_new, "new"},
63 {Opt_load, "load"},
64 {Opt_update, "update"},
65 {Opt_err, NULL}
66 };
67
68 /*
69 * datablob_parse - parse the keyctl data and fill in the
70 * payload structure
71 *
72 * On success returns 0, otherwise -EINVAL.
73 */
datablob_parse(char ** datablob,struct trusted_key_payload * p)74 static int datablob_parse(char **datablob, struct trusted_key_payload *p)
75 {
76 substring_t args[MAX_OPT_ARGS];
77 long keylen;
78 int ret = -EINVAL;
79 int key_cmd;
80 char *c;
81
82 /* main command */
83 c = strsep(datablob, " \t");
84 if (!c)
85 return -EINVAL;
86 key_cmd = match_token(c, key_tokens, args);
87 switch (key_cmd) {
88 case Opt_new:
89 /* first argument is key size */
90 c = strsep(datablob, " \t");
91 if (!c)
92 return -EINVAL;
93 ret = kstrtol(c, 10, &keylen);
94 if (ret < 0 || keylen < MIN_KEY_SIZE || keylen > MAX_KEY_SIZE)
95 return -EINVAL;
96 p->key_len = keylen;
97 ret = Opt_new;
98 break;
99 case Opt_load:
100 /* first argument is sealed blob */
101 c = strsep(datablob, " \t");
102 if (!c)
103 return -EINVAL;
104 p->blob_len = strlen(c) / 2;
105 if (p->blob_len > MAX_BLOB_SIZE)
106 return -EINVAL;
107 ret = hex2bin(p->blob, c, p->blob_len);
108 if (ret < 0)
109 return -EINVAL;
110 ret = Opt_load;
111 break;
112 case Opt_update:
113 ret = Opt_update;
114 break;
115 case Opt_err:
116 return -EINVAL;
117 }
118 return ret;
119 }
120
trusted_payload_alloc(struct key * key)121 static struct trusted_key_payload *trusted_payload_alloc(struct key *key)
122 {
123 struct trusted_key_payload *p = NULL;
124 int ret;
125
126 ret = key_payload_reserve(key, sizeof(*p));
127 if (ret < 0)
128 goto err;
129 p = kzalloc(sizeof(*p), GFP_KERNEL);
130 if (!p)
131 goto err;
132
133 p->migratable = migratable;
134 err:
135 return p;
136 }
137
138 /*
139 * trusted_instantiate - create a new trusted key
140 *
141 * Unseal an existing trusted blob or, for a new key, get a
142 * random key, then seal and create a trusted key-type key,
143 * adding it to the specified keyring.
144 *
145 * On success, return 0. Otherwise return errno.
146 */
trusted_instantiate(struct key * key,struct key_preparsed_payload * prep)147 static int trusted_instantiate(struct key *key,
148 struct key_preparsed_payload *prep)
149 {
150 struct trusted_key_payload *payload = NULL;
151 size_t datalen = prep->datalen;
152 char *datablob, *orig_datablob;
153 int ret = 0;
154 int key_cmd;
155 size_t key_len;
156
157 if (datalen <= 0 || datalen > 32767 || !prep->data)
158 return -EINVAL;
159
160 orig_datablob = datablob = kmalloc(datalen + 1, GFP_KERNEL);
161 if (!datablob)
162 return -ENOMEM;
163 memcpy(datablob, prep->data, datalen);
164 datablob[datalen] = '\0';
165
166 payload = trusted_payload_alloc(key);
167 if (!payload) {
168 ret = -ENOMEM;
169 goto out;
170 }
171
172 key_cmd = datablob_parse(&datablob, payload);
173 if (key_cmd < 0) {
174 ret = key_cmd;
175 goto out;
176 }
177
178 dump_payload(payload);
179
180 switch (key_cmd) {
181 case Opt_load:
182 ret = static_call(trusted_key_unseal)(payload, datablob);
183 dump_payload(payload);
184 if (ret < 0)
185 pr_info("key_unseal failed (%d)\n", ret);
186 break;
187 case Opt_new:
188 key_len = payload->key_len;
189 ret = static_call(trusted_key_get_random)(payload->key,
190 key_len);
191 if (ret < 0)
192 goto out;
193
194 if (ret != key_len) {
195 pr_info("key_create failed (%d)\n", ret);
196 ret = -EIO;
197 goto out;
198 }
199
200 ret = static_call(trusted_key_seal)(payload, datablob);
201 if (ret < 0)
202 pr_info("key_seal failed (%d)\n", ret);
203 break;
204 default:
205 ret = -EINVAL;
206 }
207 out:
208 kfree_sensitive(orig_datablob);
209 if (!ret)
210 rcu_assign_keypointer(key, payload);
211 else
212 kfree_sensitive(payload);
213 return ret;
214 }
215
trusted_rcu_free(struct rcu_head * rcu)216 static void trusted_rcu_free(struct rcu_head *rcu)
217 {
218 struct trusted_key_payload *p;
219
220 p = container_of(rcu, struct trusted_key_payload, rcu);
221 kfree_sensitive(p);
222 }
223
224 /*
225 * trusted_update - reseal an existing key with new PCR values
226 */
trusted_update(struct key * key,struct key_preparsed_payload * prep)227 static int trusted_update(struct key *key, struct key_preparsed_payload *prep)
228 {
229 struct trusted_key_payload *p;
230 struct trusted_key_payload *new_p;
231 size_t datalen = prep->datalen;
232 char *datablob, *orig_datablob;
233 int ret = 0;
234
235 if (key_is_negative(key))
236 return -ENOKEY;
237 p = key->payload.data[0];
238 if (!p->migratable)
239 return -EPERM;
240 if (datalen <= 0 || datalen > 32767 || !prep->data)
241 return -EINVAL;
242
243 orig_datablob = datablob = kmalloc(datalen + 1, GFP_KERNEL);
244 if (!datablob)
245 return -ENOMEM;
246
247 new_p = trusted_payload_alloc(key);
248 if (!new_p) {
249 ret = -ENOMEM;
250 goto out;
251 }
252
253 memcpy(datablob, prep->data, datalen);
254 datablob[datalen] = '\0';
255 ret = datablob_parse(&datablob, new_p);
256 if (ret != Opt_update) {
257 ret = -EINVAL;
258 kfree_sensitive(new_p);
259 goto out;
260 }
261
262 /* copy old key values, and reseal with new pcrs */
263 new_p->migratable = p->migratable;
264 new_p->key_len = p->key_len;
265 memcpy(new_p->key, p->key, p->key_len);
266 dump_payload(p);
267 dump_payload(new_p);
268
269 ret = static_call(trusted_key_seal)(new_p, datablob);
270 if (ret < 0) {
271 pr_info("key_seal failed (%d)\n", ret);
272 kfree_sensitive(new_p);
273 goto out;
274 }
275
276 rcu_assign_keypointer(key, new_p);
277 call_rcu(&p->rcu, trusted_rcu_free);
278 out:
279 kfree_sensitive(orig_datablob);
280 return ret;
281 }
282
283 /*
284 * trusted_read - copy the sealed blob data to userspace in hex.
285 * On success, return to userspace the trusted key datablob size.
286 */
trusted_read(const struct key * key,char * buffer,size_t buflen)287 static long trusted_read(const struct key *key, char *buffer,
288 size_t buflen)
289 {
290 const struct trusted_key_payload *p;
291 char *bufp;
292 int i;
293
294 p = dereference_key_locked(key);
295 if (!p)
296 return -EINVAL;
297
298 if (buffer && buflen >= 2 * p->blob_len) {
299 bufp = buffer;
300 for (i = 0; i < p->blob_len; i++)
301 bufp = hex_byte_pack(bufp, p->blob[i]);
302 }
303 return 2 * p->blob_len;
304 }
305
306 /*
307 * trusted_destroy - clear and free the key's payload
308 */
trusted_destroy(struct key * key)309 static void trusted_destroy(struct key *key)
310 {
311 kfree_sensitive(key->payload.data[0]);
312 }
313
314 struct key_type key_type_trusted = {
315 .name = "trusted",
316 .instantiate = trusted_instantiate,
317 .update = trusted_update,
318 .destroy = trusted_destroy,
319 .describe = user_describe,
320 .read = trusted_read,
321 };
322 EXPORT_SYMBOL_GPL(key_type_trusted);
323
kernel_get_random(unsigned char * key,size_t key_len)324 static int kernel_get_random(unsigned char *key, size_t key_len)
325 {
326 return get_random_bytes_wait(key, key_len) ?: key_len;
327 }
328
init_trusted(void)329 static int __init init_trusted(void)
330 {
331 int (*get_random)(unsigned char *key, size_t key_len);
332 int i, ret = 0;
333
334 for (i = 0; i < ARRAY_SIZE(trusted_key_sources); i++) {
335 if (trusted_key_source &&
336 strncmp(trusted_key_source, trusted_key_sources[i].name,
337 strlen(trusted_key_sources[i].name)))
338 continue;
339
340 /*
341 * We always support trusted.rng="kernel" and "default" as
342 * well as trusted.rng=$trusted.source if the trust source
343 * defines its own get_random callback.
344 */
345 get_random = trusted_key_sources[i].ops->get_random;
346 if (trusted_rng && strcmp(trusted_rng, "default")) {
347 if (!strcmp(trusted_rng, "kernel")) {
348 get_random = kernel_get_random;
349 } else if (strcmp(trusted_rng, trusted_key_sources[i].name) ||
350 !get_random) {
351 pr_warn("Unsupported RNG. Supported: kernel");
352 if (get_random)
353 pr_cont(", %s", trusted_key_sources[i].name);
354 pr_cont(", default\n");
355 return -EINVAL;
356 }
357 }
358
359 if (!get_random)
360 get_random = kernel_get_random;
361
362 static_call_update(trusted_key_init,
363 trusted_key_sources[i].ops->init);
364 static_call_update(trusted_key_seal,
365 trusted_key_sources[i].ops->seal);
366 static_call_update(trusted_key_unseal,
367 trusted_key_sources[i].ops->unseal);
368 static_call_update(trusted_key_get_random,
369 get_random);
370 static_call_update(trusted_key_exit,
371 trusted_key_sources[i].ops->exit);
372 migratable = trusted_key_sources[i].ops->migratable;
373
374 ret = static_call(trusted_key_init)();
375 if (!ret)
376 break;
377 }
378
379 /*
380 * encrypted_keys.ko depends on successful load of this module even if
381 * trusted key implementation is not found.
382 */
383 if (ret == -ENODEV)
384 return 0;
385
386 return ret;
387 }
388
cleanup_trusted(void)389 static void __exit cleanup_trusted(void)
390 {
391 static_call_cond(trusted_key_exit)();
392 }
393
394 late_initcall(init_trusted);
395 module_exit(cleanup_trusted);
396
397 MODULE_LICENSE("GPL");
398