1 // SPDX-License-Identifier: GPL-2.0
2 #define pr_fmt(fmt) "ASYM-TPM: "fmt
3 #include <linux/slab.h>
4 #include <linux/module.h>
5 #include <linux/export.h>
6 #include <linux/kernel.h>
7 #include <linux/seq_file.h>
8 #include <linux/scatterlist.h>
9 #include <linux/tpm.h>
10 #include <linux/tpm_command.h>
11 #include <crypto/akcipher.h>
12 #include <crypto/hash.h>
13 #include <crypto/sha.h>
14 #include <asm/unaligned.h>
15 #include <keys/asymmetric-subtype.h>
16 #include <keys/trusted.h>
17 #include <crypto/asym_tpm_subtype.h>
18 #include <crypto/public_key.h>
19
20 #define TPM_ORD_FLUSHSPECIFIC 186
21 #define TPM_ORD_LOADKEY2 65
22 #define TPM_ORD_UNBIND 30
23 #define TPM_ORD_SIGN 60
24 #define TPM_LOADKEY2_SIZE 59
25 #define TPM_FLUSHSPECIFIC_SIZE 18
26 #define TPM_UNBIND_SIZE 63
27 #define TPM_SIGN_SIZE 63
28
29 #define TPM_RT_KEY 0x00000001
30
31 /*
32 * Load a TPM key from the blob provided by userspace
33 */
tpm_loadkey2(struct tpm_buf * tb,uint32_t keyhandle,unsigned char * keyauth,const unsigned char * keyblob,int keybloblen,uint32_t * newhandle)34 static int tpm_loadkey2(struct tpm_buf *tb,
35 uint32_t keyhandle, unsigned char *keyauth,
36 const unsigned char *keyblob, int keybloblen,
37 uint32_t *newhandle)
38 {
39 unsigned char nonceodd[TPM_NONCE_SIZE];
40 unsigned char enonce[TPM_NONCE_SIZE];
41 unsigned char authdata[SHA1_DIGEST_SIZE];
42 uint32_t authhandle = 0;
43 unsigned char cont = 0;
44 uint32_t ordinal;
45 int ret;
46
47 ordinal = htonl(TPM_ORD_LOADKEY2);
48
49 /* session for loading the key */
50 ret = oiap(tb, &authhandle, enonce);
51 if (ret < 0) {
52 pr_info("oiap failed (%d)\n", ret);
53 return ret;
54 }
55
56 /* generate odd nonce */
57 ret = tpm_get_random(NULL, nonceodd, TPM_NONCE_SIZE);
58 if (ret < 0) {
59 pr_info("tpm_get_random failed (%d)\n", ret);
60 return ret;
61 }
62
63 /* calculate authorization HMAC value */
64 ret = TSS_authhmac(authdata, keyauth, SHA1_DIGEST_SIZE, enonce,
65 nonceodd, cont, sizeof(uint32_t), &ordinal,
66 keybloblen, keyblob, 0, 0);
67 if (ret < 0)
68 return ret;
69
70 /* build the request buffer */
71 INIT_BUF(tb);
72 store16(tb, TPM_TAG_RQU_AUTH1_COMMAND);
73 store32(tb, TPM_LOADKEY2_SIZE + keybloblen);
74 store32(tb, TPM_ORD_LOADKEY2);
75 store32(tb, keyhandle);
76 storebytes(tb, keyblob, keybloblen);
77 store32(tb, authhandle);
78 storebytes(tb, nonceodd, TPM_NONCE_SIZE);
79 store8(tb, cont);
80 storebytes(tb, authdata, SHA1_DIGEST_SIZE);
81
82 ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
83 if (ret < 0) {
84 pr_info("authhmac failed (%d)\n", ret);
85 return ret;
86 }
87
88 ret = TSS_checkhmac1(tb->data, ordinal, nonceodd, keyauth,
89 SHA1_DIGEST_SIZE, 0, 0);
90 if (ret < 0) {
91 pr_info("TSS_checkhmac1 failed (%d)\n", ret);
92 return ret;
93 }
94
95 *newhandle = LOAD32(tb->data, TPM_DATA_OFFSET);
96 return 0;
97 }
98
99 /*
100 * Execute the FlushSpecific TPM command
101 */
tpm_flushspecific(struct tpm_buf * tb,uint32_t handle)102 static int tpm_flushspecific(struct tpm_buf *tb, uint32_t handle)
103 {
104 INIT_BUF(tb);
105 store16(tb, TPM_TAG_RQU_COMMAND);
106 store32(tb, TPM_FLUSHSPECIFIC_SIZE);
107 store32(tb, TPM_ORD_FLUSHSPECIFIC);
108 store32(tb, handle);
109 store32(tb, TPM_RT_KEY);
110
111 return trusted_tpm_send(tb->data, MAX_BUF_SIZE);
112 }
113
114 /*
115 * Decrypt a blob provided by userspace using a specific key handle.
116 * The handle is a well known handle or previously loaded by e.g. LoadKey2
117 */
tpm_unbind(struct tpm_buf * tb,uint32_t keyhandle,unsigned char * keyauth,const unsigned char * blob,uint32_t bloblen,void * out,uint32_t outlen)118 static int tpm_unbind(struct tpm_buf *tb,
119 uint32_t keyhandle, unsigned char *keyauth,
120 const unsigned char *blob, uint32_t bloblen,
121 void *out, uint32_t outlen)
122 {
123 unsigned char nonceodd[TPM_NONCE_SIZE];
124 unsigned char enonce[TPM_NONCE_SIZE];
125 unsigned char authdata[SHA1_DIGEST_SIZE];
126 uint32_t authhandle = 0;
127 unsigned char cont = 0;
128 uint32_t ordinal;
129 uint32_t datalen;
130 int ret;
131
132 ordinal = htonl(TPM_ORD_UNBIND);
133 datalen = htonl(bloblen);
134
135 /* session for loading the key */
136 ret = oiap(tb, &authhandle, enonce);
137 if (ret < 0) {
138 pr_info("oiap failed (%d)\n", ret);
139 return ret;
140 }
141
142 /* generate odd nonce */
143 ret = tpm_get_random(NULL, nonceodd, TPM_NONCE_SIZE);
144 if (ret < 0) {
145 pr_info("tpm_get_random failed (%d)\n", ret);
146 return ret;
147 }
148
149 /* calculate authorization HMAC value */
150 ret = TSS_authhmac(authdata, keyauth, SHA1_DIGEST_SIZE, enonce,
151 nonceodd, cont, sizeof(uint32_t), &ordinal,
152 sizeof(uint32_t), &datalen,
153 bloblen, blob, 0, 0);
154 if (ret < 0)
155 return ret;
156
157 /* build the request buffer */
158 INIT_BUF(tb);
159 store16(tb, TPM_TAG_RQU_AUTH1_COMMAND);
160 store32(tb, TPM_UNBIND_SIZE + bloblen);
161 store32(tb, TPM_ORD_UNBIND);
162 store32(tb, keyhandle);
163 store32(tb, bloblen);
164 storebytes(tb, blob, bloblen);
165 store32(tb, authhandle);
166 storebytes(tb, nonceodd, TPM_NONCE_SIZE);
167 store8(tb, cont);
168 storebytes(tb, authdata, SHA1_DIGEST_SIZE);
169
170 ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
171 if (ret < 0) {
172 pr_info("authhmac failed (%d)\n", ret);
173 return ret;
174 }
175
176 datalen = LOAD32(tb->data, TPM_DATA_OFFSET);
177
178 ret = TSS_checkhmac1(tb->data, ordinal, nonceodd,
179 keyauth, SHA1_DIGEST_SIZE,
180 sizeof(uint32_t), TPM_DATA_OFFSET,
181 datalen, TPM_DATA_OFFSET + sizeof(uint32_t),
182 0, 0);
183 if (ret < 0) {
184 pr_info("TSS_checkhmac1 failed (%d)\n", ret);
185 return ret;
186 }
187
188 memcpy(out, tb->data + TPM_DATA_OFFSET + sizeof(uint32_t),
189 min(outlen, datalen));
190
191 return datalen;
192 }
193
194 /*
195 * Sign a blob provided by userspace (that has had the hash function applied)
196 * using a specific key handle. The handle is assumed to have been previously
197 * loaded by e.g. LoadKey2.
198 *
199 * Note that the key signature scheme of the used key should be set to
200 * TPM_SS_RSASSAPKCS1v15_DER. This allows the hashed input to be of any size
201 * up to key_length_in_bytes - 11 and not be limited to size 20 like the
202 * TPM_SS_RSASSAPKCS1v15_SHA1 signature scheme.
203 */
tpm_sign(struct tpm_buf * tb,uint32_t keyhandle,unsigned char * keyauth,const unsigned char * blob,uint32_t bloblen,void * out,uint32_t outlen)204 static int tpm_sign(struct tpm_buf *tb,
205 uint32_t keyhandle, unsigned char *keyauth,
206 const unsigned char *blob, uint32_t bloblen,
207 void *out, uint32_t outlen)
208 {
209 unsigned char nonceodd[TPM_NONCE_SIZE];
210 unsigned char enonce[TPM_NONCE_SIZE];
211 unsigned char authdata[SHA1_DIGEST_SIZE];
212 uint32_t authhandle = 0;
213 unsigned char cont = 0;
214 uint32_t ordinal;
215 uint32_t datalen;
216 int ret;
217
218 ordinal = htonl(TPM_ORD_SIGN);
219 datalen = htonl(bloblen);
220
221 /* session for loading the key */
222 ret = oiap(tb, &authhandle, enonce);
223 if (ret < 0) {
224 pr_info("oiap failed (%d)\n", ret);
225 return ret;
226 }
227
228 /* generate odd nonce */
229 ret = tpm_get_random(NULL, nonceodd, TPM_NONCE_SIZE);
230 if (ret < 0) {
231 pr_info("tpm_get_random failed (%d)\n", ret);
232 return ret;
233 }
234
235 /* calculate authorization HMAC value */
236 ret = TSS_authhmac(authdata, keyauth, SHA1_DIGEST_SIZE, enonce,
237 nonceodd, cont, sizeof(uint32_t), &ordinal,
238 sizeof(uint32_t), &datalen,
239 bloblen, blob, 0, 0);
240 if (ret < 0)
241 return ret;
242
243 /* build the request buffer */
244 INIT_BUF(tb);
245 store16(tb, TPM_TAG_RQU_AUTH1_COMMAND);
246 store32(tb, TPM_SIGN_SIZE + bloblen);
247 store32(tb, TPM_ORD_SIGN);
248 store32(tb, keyhandle);
249 store32(tb, bloblen);
250 storebytes(tb, blob, bloblen);
251 store32(tb, authhandle);
252 storebytes(tb, nonceodd, TPM_NONCE_SIZE);
253 store8(tb, cont);
254 storebytes(tb, authdata, SHA1_DIGEST_SIZE);
255
256 ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
257 if (ret < 0) {
258 pr_info("authhmac failed (%d)\n", ret);
259 return ret;
260 }
261
262 datalen = LOAD32(tb->data, TPM_DATA_OFFSET);
263
264 ret = TSS_checkhmac1(tb->data, ordinal, nonceodd,
265 keyauth, SHA1_DIGEST_SIZE,
266 sizeof(uint32_t), TPM_DATA_OFFSET,
267 datalen, TPM_DATA_OFFSET + sizeof(uint32_t),
268 0, 0);
269 if (ret < 0) {
270 pr_info("TSS_checkhmac1 failed (%d)\n", ret);
271 return ret;
272 }
273
274 memcpy(out, tb->data + TPM_DATA_OFFSET + sizeof(uint32_t),
275 min(datalen, outlen));
276
277 return datalen;
278 }
279
280 /* Room to fit two u32 zeros for algo id and parameters length. */
281 #define SETKEY_PARAMS_SIZE (sizeof(u32) * 2)
282
283 /*
284 * Maximum buffer size for the BER/DER encoded public key. The public key
285 * is of the form SEQUENCE { INTEGER n, INTEGER e } where n is a maximum 2048
286 * bit key and e is usually 65537
287 * The encoding overhead is:
288 * - max 4 bytes for SEQUENCE
289 * - max 4 bytes for INTEGER n type/length
290 * - 257 bytes of n
291 * - max 2 bytes for INTEGER e type/length
292 * - 3 bytes of e
293 * - 4+4 of zeros for set_pub_key parameters (SETKEY_PARAMS_SIZE)
294 */
295 #define PUB_KEY_BUF_SIZE (4 + 4 + 257 + 2 + 3 + SETKEY_PARAMS_SIZE)
296
297 /*
298 * Provide a part of a description of the key for /proc/keys.
299 */
asym_tpm_describe(const struct key * asymmetric_key,struct seq_file * m)300 static void asym_tpm_describe(const struct key *asymmetric_key,
301 struct seq_file *m)
302 {
303 struct tpm_key *tk = asymmetric_key->payload.data[asym_crypto];
304
305 if (!tk)
306 return;
307
308 seq_printf(m, "TPM1.2/Blob");
309 }
310
asym_tpm_destroy(void * payload0,void * payload3)311 static void asym_tpm_destroy(void *payload0, void *payload3)
312 {
313 struct tpm_key *tk = payload0;
314
315 if (!tk)
316 return;
317
318 kfree(tk->blob);
319 tk->blob_len = 0;
320
321 kfree(tk);
322 }
323
324 /* How many bytes will it take to encode the length */
definite_length(uint32_t len)325 static inline uint32_t definite_length(uint32_t len)
326 {
327 if (len <= 127)
328 return 1;
329 if (len <= 255)
330 return 2;
331 return 3;
332 }
333
encode_tag_length(uint8_t * buf,uint8_t tag,uint32_t len)334 static inline uint8_t *encode_tag_length(uint8_t *buf, uint8_t tag,
335 uint32_t len)
336 {
337 *buf++ = tag;
338
339 if (len <= 127) {
340 buf[0] = len;
341 return buf + 1;
342 }
343
344 if (len <= 255) {
345 buf[0] = 0x81;
346 buf[1] = len;
347 return buf + 2;
348 }
349
350 buf[0] = 0x82;
351 put_unaligned_be16(len, buf + 1);
352 return buf + 3;
353 }
354
derive_pub_key(const void * pub_key,uint32_t len,uint8_t * buf)355 static uint32_t derive_pub_key(const void *pub_key, uint32_t len, uint8_t *buf)
356 {
357 uint8_t *cur = buf;
358 uint32_t n_len = definite_length(len) + 1 + len + 1;
359 uint32_t e_len = definite_length(3) + 1 + 3;
360 uint8_t e[3] = { 0x01, 0x00, 0x01 };
361
362 /* SEQUENCE */
363 cur = encode_tag_length(cur, 0x30, n_len + e_len);
364 /* INTEGER n */
365 cur = encode_tag_length(cur, 0x02, len + 1);
366 cur[0] = 0x00;
367 memcpy(cur + 1, pub_key, len);
368 cur += len + 1;
369 cur = encode_tag_length(cur, 0x02, sizeof(e));
370 memcpy(cur, e, sizeof(e));
371 cur += sizeof(e);
372 /* Zero parameters to satisfy set_pub_key ABI. */
373 memset(cur, 0, SETKEY_PARAMS_SIZE);
374
375 return cur - buf;
376 }
377
378 /*
379 * Determine the crypto algorithm name.
380 */
determine_akcipher(const char * encoding,const char * hash_algo,char alg_name[CRYPTO_MAX_ALG_NAME])381 static int determine_akcipher(const char *encoding, const char *hash_algo,
382 char alg_name[CRYPTO_MAX_ALG_NAME])
383 {
384 if (strcmp(encoding, "pkcs1") == 0) {
385 if (!hash_algo) {
386 strcpy(alg_name, "pkcs1pad(rsa)");
387 return 0;
388 }
389
390 if (snprintf(alg_name, CRYPTO_MAX_ALG_NAME, "pkcs1pad(rsa,%s)",
391 hash_algo) >= CRYPTO_MAX_ALG_NAME)
392 return -EINVAL;
393
394 return 0;
395 }
396
397 if (strcmp(encoding, "raw") == 0) {
398 strcpy(alg_name, "rsa");
399 return 0;
400 }
401
402 return -ENOPKG;
403 }
404
405 /*
406 * Query information about a key.
407 */
tpm_key_query(const struct kernel_pkey_params * params,struct kernel_pkey_query * info)408 static int tpm_key_query(const struct kernel_pkey_params *params,
409 struct kernel_pkey_query *info)
410 {
411 struct tpm_key *tk = params->key->payload.data[asym_crypto];
412 int ret;
413 char alg_name[CRYPTO_MAX_ALG_NAME];
414 struct crypto_akcipher *tfm;
415 uint8_t der_pub_key[PUB_KEY_BUF_SIZE];
416 uint32_t der_pub_key_len;
417 int len;
418
419 /* TPM only works on private keys, public keys still done in software */
420 ret = determine_akcipher(params->encoding, params->hash_algo, alg_name);
421 if (ret < 0)
422 return ret;
423
424 tfm = crypto_alloc_akcipher(alg_name, 0, 0);
425 if (IS_ERR(tfm))
426 return PTR_ERR(tfm);
427
428 der_pub_key_len = derive_pub_key(tk->pub_key, tk->pub_key_len,
429 der_pub_key);
430
431 ret = crypto_akcipher_set_pub_key(tfm, der_pub_key, der_pub_key_len);
432 if (ret < 0)
433 goto error_free_tfm;
434
435 len = crypto_akcipher_maxsize(tfm);
436
437 info->key_size = tk->key_len;
438 info->max_data_size = tk->key_len / 8;
439 info->max_sig_size = len;
440 info->max_enc_size = len;
441 info->max_dec_size = tk->key_len / 8;
442
443 info->supported_ops = KEYCTL_SUPPORTS_ENCRYPT |
444 KEYCTL_SUPPORTS_DECRYPT |
445 KEYCTL_SUPPORTS_VERIFY |
446 KEYCTL_SUPPORTS_SIGN;
447
448 ret = 0;
449 error_free_tfm:
450 crypto_free_akcipher(tfm);
451 pr_devel("<==%s() = %d\n", __func__, ret);
452 return ret;
453 }
454
455 /*
456 * Encryption operation is performed with the public key. Hence it is done
457 * in software
458 */
tpm_key_encrypt(struct tpm_key * tk,struct kernel_pkey_params * params,const void * in,void * out)459 static int tpm_key_encrypt(struct tpm_key *tk,
460 struct kernel_pkey_params *params,
461 const void *in, void *out)
462 {
463 char alg_name[CRYPTO_MAX_ALG_NAME];
464 struct crypto_akcipher *tfm;
465 struct akcipher_request *req;
466 struct crypto_wait cwait;
467 struct scatterlist in_sg, out_sg;
468 uint8_t der_pub_key[PUB_KEY_BUF_SIZE];
469 uint32_t der_pub_key_len;
470 int ret;
471
472 pr_devel("==>%s()\n", __func__);
473
474 ret = determine_akcipher(params->encoding, params->hash_algo, alg_name);
475 if (ret < 0)
476 return ret;
477
478 tfm = crypto_alloc_akcipher(alg_name, 0, 0);
479 if (IS_ERR(tfm))
480 return PTR_ERR(tfm);
481
482 der_pub_key_len = derive_pub_key(tk->pub_key, tk->pub_key_len,
483 der_pub_key);
484
485 ret = crypto_akcipher_set_pub_key(tfm, der_pub_key, der_pub_key_len);
486 if (ret < 0)
487 goto error_free_tfm;
488
489 req = akcipher_request_alloc(tfm, GFP_KERNEL);
490 if (!req)
491 goto error_free_tfm;
492
493 sg_init_one(&in_sg, in, params->in_len);
494 sg_init_one(&out_sg, out, params->out_len);
495 akcipher_request_set_crypt(req, &in_sg, &out_sg, params->in_len,
496 params->out_len);
497 crypto_init_wait(&cwait);
498 akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
499 CRYPTO_TFM_REQ_MAY_SLEEP,
500 crypto_req_done, &cwait);
501
502 ret = crypto_akcipher_encrypt(req);
503 ret = crypto_wait_req(ret, &cwait);
504
505 if (ret == 0)
506 ret = req->dst_len;
507
508 akcipher_request_free(req);
509 error_free_tfm:
510 crypto_free_akcipher(tfm);
511 pr_devel("<==%s() = %d\n", __func__, ret);
512 return ret;
513 }
514
515 /*
516 * Decryption operation is performed with the private key in the TPM.
517 */
tpm_key_decrypt(struct tpm_key * tk,struct kernel_pkey_params * params,const void * in,void * out)518 static int tpm_key_decrypt(struct tpm_key *tk,
519 struct kernel_pkey_params *params,
520 const void *in, void *out)
521 {
522 struct tpm_buf *tb;
523 uint32_t keyhandle;
524 uint8_t srkauth[SHA1_DIGEST_SIZE];
525 uint8_t keyauth[SHA1_DIGEST_SIZE];
526 int r;
527
528 pr_devel("==>%s()\n", __func__);
529
530 if (params->hash_algo)
531 return -ENOPKG;
532
533 if (strcmp(params->encoding, "pkcs1"))
534 return -ENOPKG;
535
536 tb = kzalloc(sizeof(*tb), GFP_KERNEL);
537 if (!tb)
538 return -ENOMEM;
539
540 /* TODO: Handle a non-all zero SRK authorization */
541 memset(srkauth, 0, sizeof(srkauth));
542
543 r = tpm_loadkey2(tb, SRKHANDLE, srkauth,
544 tk->blob, tk->blob_len, &keyhandle);
545 if (r < 0) {
546 pr_devel("loadkey2 failed (%d)\n", r);
547 goto error;
548 }
549
550 /* TODO: Handle a non-all zero key authorization */
551 memset(keyauth, 0, sizeof(keyauth));
552
553 r = tpm_unbind(tb, keyhandle, keyauth,
554 in, params->in_len, out, params->out_len);
555 if (r < 0)
556 pr_devel("tpm_unbind failed (%d)\n", r);
557
558 if (tpm_flushspecific(tb, keyhandle) < 0)
559 pr_devel("flushspecific failed (%d)\n", r);
560
561 error:
562 kzfree(tb);
563 pr_devel("<==%s() = %d\n", __func__, r);
564 return r;
565 }
566
567 /*
568 * Hash algorithm OIDs plus ASN.1 DER wrappings [RFC4880 sec 5.2.2].
569 */
570 static const u8 digest_info_md5[] = {
571 0x30, 0x20, 0x30, 0x0c, 0x06, 0x08,
572 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05, /* OID */
573 0x05, 0x00, 0x04, 0x10
574 };
575
576 static const u8 digest_info_sha1[] = {
577 0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
578 0x2b, 0x0e, 0x03, 0x02, 0x1a,
579 0x05, 0x00, 0x04, 0x14
580 };
581
582 static const u8 digest_info_rmd160[] = {
583 0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
584 0x2b, 0x24, 0x03, 0x02, 0x01,
585 0x05, 0x00, 0x04, 0x14
586 };
587
588 static const u8 digest_info_sha224[] = {
589 0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09,
590 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04,
591 0x05, 0x00, 0x04, 0x1c
592 };
593
594 static const u8 digest_info_sha256[] = {
595 0x30, 0x31, 0x30, 0x0d, 0x06, 0x09,
596 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
597 0x05, 0x00, 0x04, 0x20
598 };
599
600 static const u8 digest_info_sha384[] = {
601 0x30, 0x41, 0x30, 0x0d, 0x06, 0x09,
602 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02,
603 0x05, 0x00, 0x04, 0x30
604 };
605
606 static const u8 digest_info_sha512[] = {
607 0x30, 0x51, 0x30, 0x0d, 0x06, 0x09,
608 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03,
609 0x05, 0x00, 0x04, 0x40
610 };
611
612 static const struct asn1_template {
613 const char *name;
614 const u8 *data;
615 size_t size;
616 } asn1_templates[] = {
617 #define _(X) { #X, digest_info_##X, sizeof(digest_info_##X) }
618 _(md5),
619 _(sha1),
620 _(rmd160),
621 _(sha256),
622 _(sha384),
623 _(sha512),
624 _(sha224),
625 { NULL }
626 #undef _
627 };
628
lookup_asn1(const char * name)629 static const struct asn1_template *lookup_asn1(const char *name)
630 {
631 const struct asn1_template *p;
632
633 for (p = asn1_templates; p->name; p++)
634 if (strcmp(name, p->name) == 0)
635 return p;
636 return NULL;
637 }
638
639 /*
640 * Sign operation is performed with the private key in the TPM.
641 */
tpm_key_sign(struct tpm_key * tk,struct kernel_pkey_params * params,const void * in,void * out)642 static int tpm_key_sign(struct tpm_key *tk,
643 struct kernel_pkey_params *params,
644 const void *in, void *out)
645 {
646 struct tpm_buf *tb;
647 uint32_t keyhandle;
648 uint8_t srkauth[SHA1_DIGEST_SIZE];
649 uint8_t keyauth[SHA1_DIGEST_SIZE];
650 void *asn1_wrapped = NULL;
651 uint32_t in_len = params->in_len;
652 int r;
653
654 pr_devel("==>%s()\n", __func__);
655
656 if (strcmp(params->encoding, "pkcs1"))
657 return -ENOPKG;
658
659 if (params->hash_algo) {
660 const struct asn1_template *asn1 =
661 lookup_asn1(params->hash_algo);
662
663 if (!asn1)
664 return -ENOPKG;
665
666 /* request enough space for the ASN.1 template + input hash */
667 asn1_wrapped = kzalloc(in_len + asn1->size, GFP_KERNEL);
668 if (!asn1_wrapped)
669 return -ENOMEM;
670
671 /* Copy ASN.1 template, then the input */
672 memcpy(asn1_wrapped, asn1->data, asn1->size);
673 memcpy(asn1_wrapped + asn1->size, in, in_len);
674
675 in = asn1_wrapped;
676 in_len += asn1->size;
677 }
678
679 if (in_len > tk->key_len / 8 - 11) {
680 r = -EOVERFLOW;
681 goto error_free_asn1_wrapped;
682 }
683
684 r = -ENOMEM;
685 tb = kzalloc(sizeof(*tb), GFP_KERNEL);
686 if (!tb)
687 goto error_free_asn1_wrapped;
688
689 /* TODO: Handle a non-all zero SRK authorization */
690 memset(srkauth, 0, sizeof(srkauth));
691
692 r = tpm_loadkey2(tb, SRKHANDLE, srkauth,
693 tk->blob, tk->blob_len, &keyhandle);
694 if (r < 0) {
695 pr_devel("loadkey2 failed (%d)\n", r);
696 goto error_free_tb;
697 }
698
699 /* TODO: Handle a non-all zero key authorization */
700 memset(keyauth, 0, sizeof(keyauth));
701
702 r = tpm_sign(tb, keyhandle, keyauth, in, in_len, out, params->out_len);
703 if (r < 0)
704 pr_devel("tpm_sign failed (%d)\n", r);
705
706 if (tpm_flushspecific(tb, keyhandle) < 0)
707 pr_devel("flushspecific failed (%d)\n", r);
708
709 error_free_tb:
710 kzfree(tb);
711 error_free_asn1_wrapped:
712 kfree(asn1_wrapped);
713 pr_devel("<==%s() = %d\n", __func__, r);
714 return r;
715 }
716
717 /*
718 * Do encryption, decryption and signing ops.
719 */
tpm_key_eds_op(struct kernel_pkey_params * params,const void * in,void * out)720 static int tpm_key_eds_op(struct kernel_pkey_params *params,
721 const void *in, void *out)
722 {
723 struct tpm_key *tk = params->key->payload.data[asym_crypto];
724 int ret = -EOPNOTSUPP;
725
726 /* Perform the encryption calculation. */
727 switch (params->op) {
728 case kernel_pkey_encrypt:
729 ret = tpm_key_encrypt(tk, params, in, out);
730 break;
731 case kernel_pkey_decrypt:
732 ret = tpm_key_decrypt(tk, params, in, out);
733 break;
734 case kernel_pkey_sign:
735 ret = tpm_key_sign(tk, params, in, out);
736 break;
737 default:
738 BUG();
739 }
740
741 return ret;
742 }
743
744 /*
745 * Verify a signature using a public key.
746 */
tpm_key_verify_signature(const struct key * key,const struct public_key_signature * sig)747 static int tpm_key_verify_signature(const struct key *key,
748 const struct public_key_signature *sig)
749 {
750 const struct tpm_key *tk = key->payload.data[asym_crypto];
751 struct crypto_wait cwait;
752 struct crypto_akcipher *tfm;
753 struct akcipher_request *req;
754 struct scatterlist src_sg[2];
755 char alg_name[CRYPTO_MAX_ALG_NAME];
756 uint8_t der_pub_key[PUB_KEY_BUF_SIZE];
757 uint32_t der_pub_key_len;
758 int ret;
759
760 pr_devel("==>%s()\n", __func__);
761
762 BUG_ON(!tk);
763 BUG_ON(!sig);
764 BUG_ON(!sig->s);
765
766 if (!sig->digest)
767 return -ENOPKG;
768
769 ret = determine_akcipher(sig->encoding, sig->hash_algo, alg_name);
770 if (ret < 0)
771 return ret;
772
773 tfm = crypto_alloc_akcipher(alg_name, 0, 0);
774 if (IS_ERR(tfm))
775 return PTR_ERR(tfm);
776
777 der_pub_key_len = derive_pub_key(tk->pub_key, tk->pub_key_len,
778 der_pub_key);
779
780 ret = crypto_akcipher_set_pub_key(tfm, der_pub_key, der_pub_key_len);
781 if (ret < 0)
782 goto error_free_tfm;
783
784 ret = -ENOMEM;
785 req = akcipher_request_alloc(tfm, GFP_KERNEL);
786 if (!req)
787 goto error_free_tfm;
788
789 sg_init_table(src_sg, 2);
790 sg_set_buf(&src_sg[0], sig->s, sig->s_size);
791 sg_set_buf(&src_sg[1], sig->digest, sig->digest_size);
792 akcipher_request_set_crypt(req, src_sg, NULL, sig->s_size,
793 sig->digest_size);
794 crypto_init_wait(&cwait);
795 akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
796 CRYPTO_TFM_REQ_MAY_SLEEP,
797 crypto_req_done, &cwait);
798 ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait);
799
800 akcipher_request_free(req);
801 error_free_tfm:
802 crypto_free_akcipher(tfm);
803 pr_devel("<==%s() = %d\n", __func__, ret);
804 if (WARN_ON_ONCE(ret > 0))
805 ret = -EINVAL;
806 return ret;
807 }
808
809 /*
810 * Parse enough information out of TPM_KEY structure:
811 * TPM_STRUCT_VER -> 4 bytes
812 * TPM_KEY_USAGE -> 2 bytes
813 * TPM_KEY_FLAGS -> 4 bytes
814 * TPM_AUTH_DATA_USAGE -> 1 byte
815 * TPM_KEY_PARMS -> variable
816 * UINT32 PCRInfoSize -> 4 bytes
817 * BYTE* -> PCRInfoSize bytes
818 * TPM_STORE_PUBKEY
819 * UINT32 encDataSize;
820 * BYTE* -> encDataSize;
821 *
822 * TPM_KEY_PARMS:
823 * TPM_ALGORITHM_ID -> 4 bytes
824 * TPM_ENC_SCHEME -> 2 bytes
825 * TPM_SIG_SCHEME -> 2 bytes
826 * UINT32 parmSize -> 4 bytes
827 * BYTE* -> variable
828 */
extract_key_parameters(struct tpm_key * tk)829 static int extract_key_parameters(struct tpm_key *tk)
830 {
831 const void *cur = tk->blob;
832 uint32_t len = tk->blob_len;
833 const void *pub_key;
834 uint32_t sz;
835 uint32_t key_len;
836
837 if (len < 11)
838 return -EBADMSG;
839
840 /* Ensure this is a legacy key */
841 if (get_unaligned_be16(cur + 4) != 0x0015)
842 return -EBADMSG;
843
844 /* Skip to TPM_KEY_PARMS */
845 cur += 11;
846 len -= 11;
847
848 if (len < 12)
849 return -EBADMSG;
850
851 /* Make sure this is an RSA key */
852 if (get_unaligned_be32(cur) != 0x00000001)
853 return -EBADMSG;
854
855 /* Make sure this is TPM_ES_RSAESPKCSv15 encoding scheme */
856 if (get_unaligned_be16(cur + 4) != 0x0002)
857 return -EBADMSG;
858
859 /* Make sure this is TPM_SS_RSASSAPKCS1v15_DER signature scheme */
860 if (get_unaligned_be16(cur + 6) != 0x0003)
861 return -EBADMSG;
862
863 sz = get_unaligned_be32(cur + 8);
864 if (len < sz + 12)
865 return -EBADMSG;
866
867 /* Move to TPM_RSA_KEY_PARMS */
868 len -= 12;
869 cur += 12;
870
871 /* Grab the RSA key length */
872 key_len = get_unaligned_be32(cur);
873
874 switch (key_len) {
875 case 512:
876 case 1024:
877 case 1536:
878 case 2048:
879 break;
880 default:
881 return -EINVAL;
882 }
883
884 /* Move just past TPM_KEY_PARMS */
885 cur += sz;
886 len -= sz;
887
888 if (len < 4)
889 return -EBADMSG;
890
891 sz = get_unaligned_be32(cur);
892 if (len < 4 + sz)
893 return -EBADMSG;
894
895 /* Move to TPM_STORE_PUBKEY */
896 cur += 4 + sz;
897 len -= 4 + sz;
898
899 /* Grab the size of the public key, it should jive with the key size */
900 sz = get_unaligned_be32(cur);
901 if (sz > 256)
902 return -EINVAL;
903
904 pub_key = cur + 4;
905
906 tk->key_len = key_len;
907 tk->pub_key = pub_key;
908 tk->pub_key_len = sz;
909
910 return 0;
911 }
912
913 /* Given the blob, parse it and load it into the TPM */
tpm_key_create(const void * blob,uint32_t blob_len)914 struct tpm_key *tpm_key_create(const void *blob, uint32_t blob_len)
915 {
916 int r;
917 struct tpm_key *tk;
918
919 r = tpm_is_tpm2(NULL);
920 if (r < 0)
921 goto error;
922
923 /* We don't support TPM2 yet */
924 if (r > 0) {
925 r = -ENODEV;
926 goto error;
927 }
928
929 r = -ENOMEM;
930 tk = kzalloc(sizeof(struct tpm_key), GFP_KERNEL);
931 if (!tk)
932 goto error;
933
934 tk->blob = kmemdup(blob, blob_len, GFP_KERNEL);
935 if (!tk->blob)
936 goto error_memdup;
937
938 tk->blob_len = blob_len;
939
940 r = extract_key_parameters(tk);
941 if (r < 0)
942 goto error_extract;
943
944 return tk;
945
946 error_extract:
947 kfree(tk->blob);
948 tk->blob_len = 0;
949 error_memdup:
950 kfree(tk);
951 error:
952 return ERR_PTR(r);
953 }
954 EXPORT_SYMBOL_GPL(tpm_key_create);
955
956 /*
957 * TPM-based asymmetric key subtype
958 */
959 struct asymmetric_key_subtype asym_tpm_subtype = {
960 .owner = THIS_MODULE,
961 .name = "asym_tpm",
962 .name_len = sizeof("asym_tpm") - 1,
963 .describe = asym_tpm_describe,
964 .destroy = asym_tpm_destroy,
965 .query = tpm_key_query,
966 .eds_op = tpm_key_eds_op,
967 .verify_signature = tpm_key_verify_signature,
968 };
969 EXPORT_SYMBOL_GPL(asym_tpm_subtype);
970
971 MODULE_DESCRIPTION("TPM based asymmetric key subtype");
972 MODULE_AUTHOR("Intel Corporation");
973 MODULE_LICENSE("GPL v2");
974
