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