1 /*
2 * Copyright (c) 2018-2022 Yubico AB. All rights reserved.
3 * Use of this source code is governed by a BSD-style
4 * license that can be found in the LICENSE file.
5 * SPDX-License-Identifier: BSD-2-Clause
6 */
7
8 #include <openssl/sha.h>
9 #include <openssl/x509.h>
10
11 #ifdef HAVE_UNISTD_H
12 #include <unistd.h>
13 #endif
14 #include <errno.h>
15
16 #include "fido.h"
17 #include "fido/es256.h"
18 #include "fallthrough.h"
19
20 #define U2F_PACE_MS (100)
21
22 #if defined(_MSC_VER)
23 static int
usleep(unsigned int usec)24 usleep(unsigned int usec)
25 {
26 Sleep(usec / 1000);
27
28 return (0);
29 }
30 #endif
31
32 static int
delay_ms(unsigned int ms,int * ms_remain)33 delay_ms(unsigned int ms, int *ms_remain)
34 {
35 if (*ms_remain > -1 && (unsigned int)*ms_remain < ms)
36 ms = (unsigned int)*ms_remain;
37
38 if (ms > UINT_MAX / 1000) {
39 fido_log_debug("%s: ms=%u", __func__, ms);
40 return (-1);
41 }
42
43 if (usleep(ms * 1000) < 0) {
44 fido_log_error(errno, "%s: usleep", __func__);
45 return (-1);
46 }
47
48 if (*ms_remain > -1)
49 *ms_remain -= (int)ms;
50
51 return (0);
52 }
53
54 static int
sig_get(fido_blob_t * sig,const unsigned char ** buf,size_t * len)55 sig_get(fido_blob_t *sig, const unsigned char **buf, size_t *len)
56 {
57 sig->len = *len; /* consume the whole buffer */
58 if ((sig->ptr = calloc(1, sig->len)) == NULL ||
59 fido_buf_read(buf, len, sig->ptr, sig->len) < 0) {
60 fido_log_debug("%s: fido_buf_read", __func__);
61 fido_blob_reset(sig);
62 return (-1);
63 }
64
65 return (0);
66 }
67
68 static int
x5c_get(fido_blob_t * x5c,const unsigned char ** buf,size_t * len)69 x5c_get(fido_blob_t *x5c, const unsigned char **buf, size_t *len)
70 {
71 X509 *cert = NULL;
72 int ok = -1;
73
74 if (*len > LONG_MAX) {
75 fido_log_debug("%s: invalid len %zu", __func__, *len);
76 goto fail;
77 }
78
79 /* find out the certificate's length */
80 const unsigned char *end = *buf;
81 if ((cert = d2i_X509(NULL, &end, (long)*len)) == NULL || end <= *buf ||
82 (x5c->len = (size_t)(end - *buf)) >= *len) {
83 fido_log_debug("%s: d2i_X509", __func__);
84 goto fail;
85 }
86
87 /* read accordingly */
88 if ((x5c->ptr = calloc(1, x5c->len)) == NULL ||
89 fido_buf_read(buf, len, x5c->ptr, x5c->len) < 0) {
90 fido_log_debug("%s: fido_buf_read", __func__);
91 goto fail;
92 }
93
94 ok = 0;
95 fail:
96 if (cert != NULL)
97 X509_free(cert);
98
99 if (ok < 0)
100 fido_blob_reset(x5c);
101
102 return (ok);
103 }
104
105 static int
authdata_fake(const char * rp_id,uint8_t flags,uint32_t sigcount,fido_blob_t * fake_cbor_ad)106 authdata_fake(const char *rp_id, uint8_t flags, uint32_t sigcount,
107 fido_blob_t *fake_cbor_ad)
108 {
109 fido_authdata_t ad;
110 cbor_item_t *item = NULL;
111 size_t alloc_len;
112
113 memset(&ad, 0, sizeof(ad));
114
115 if (SHA256((const void *)rp_id, strlen(rp_id),
116 ad.rp_id_hash) != ad.rp_id_hash) {
117 fido_log_debug("%s: sha256", __func__);
118 return (-1);
119 }
120
121 ad.flags = flags; /* XXX translate? */
122 ad.sigcount = sigcount;
123
124 if ((item = cbor_build_bytestring((const unsigned char *)&ad,
125 sizeof(ad))) == NULL) {
126 fido_log_debug("%s: cbor_build_bytestring", __func__);
127 return (-1);
128 }
129
130 if (fake_cbor_ad->ptr != NULL ||
131 (fake_cbor_ad->len = cbor_serialize_alloc(item, &fake_cbor_ad->ptr,
132 &alloc_len)) == 0) {
133 fido_log_debug("%s: cbor_serialize_alloc", __func__);
134 cbor_decref(&item);
135 return (-1);
136 }
137
138 cbor_decref(&item);
139
140 return (0);
141 }
142
143 /* TODO: use u2f_get_touch_begin & u2f_get_touch_status instead */
144 static int
send_dummy_register(fido_dev_t * dev,int * ms)145 send_dummy_register(fido_dev_t *dev, int *ms)
146 {
147 iso7816_apdu_t *apdu = NULL;
148 unsigned char *reply = NULL;
149 unsigned char challenge[SHA256_DIGEST_LENGTH];
150 unsigned char application[SHA256_DIGEST_LENGTH];
151 int r;
152
153 /* dummy challenge & application */
154 memset(&challenge, 0xff, sizeof(challenge));
155 memset(&application, 0xff, sizeof(application));
156
157 if ((apdu = iso7816_new(0, U2F_CMD_REGISTER, 0, 2 *
158 SHA256_DIGEST_LENGTH)) == NULL ||
159 iso7816_add(apdu, &challenge, sizeof(challenge)) < 0 ||
160 iso7816_add(apdu, &application, sizeof(application)) < 0) {
161 fido_log_debug("%s: iso7816", __func__);
162 r = FIDO_ERR_INTERNAL;
163 goto fail;
164 }
165
166 if ((reply = malloc(FIDO_MAXMSG)) == NULL) {
167 fido_log_debug("%s: malloc", __func__);
168 r = FIDO_ERR_INTERNAL;
169 goto fail;
170 }
171
172 do {
173 if (fido_tx(dev, CTAP_CMD_MSG, iso7816_ptr(apdu),
174 iso7816_len(apdu), ms) < 0) {
175 fido_log_debug("%s: fido_tx", __func__);
176 r = FIDO_ERR_TX;
177 goto fail;
178 }
179 if (fido_rx(dev, CTAP_CMD_MSG, reply, FIDO_MAXMSG, ms) < 2) {
180 fido_log_debug("%s: fido_rx", __func__);
181 r = FIDO_ERR_RX;
182 goto fail;
183 }
184 if (delay_ms(U2F_PACE_MS, ms) != 0) {
185 fido_log_debug("%s: delay_ms", __func__);
186 r = FIDO_ERR_RX;
187 goto fail;
188 }
189 } while (((reply[0] << 8) | reply[1]) == SW_CONDITIONS_NOT_SATISFIED);
190
191 r = FIDO_OK;
192 fail:
193 iso7816_free(&apdu);
194 freezero(reply, FIDO_MAXMSG);
195
196 return (r);
197 }
198
199 static int
key_lookup(fido_dev_t * dev,const char * rp_id,const fido_blob_t * key_id,int * found,int * ms)200 key_lookup(fido_dev_t *dev, const char *rp_id, const fido_blob_t *key_id,
201 int *found, int *ms)
202 {
203 iso7816_apdu_t *apdu = NULL;
204 unsigned char *reply = NULL;
205 unsigned char challenge[SHA256_DIGEST_LENGTH];
206 unsigned char rp_id_hash[SHA256_DIGEST_LENGTH];
207 uint8_t key_id_len;
208 int r;
209
210 if (key_id->len > UINT8_MAX || rp_id == NULL) {
211 fido_log_debug("%s: key_id->len=%zu, rp_id=%p", __func__,
212 key_id->len, (const void *)rp_id);
213 r = FIDO_ERR_INVALID_ARGUMENT;
214 goto fail;
215 }
216
217 memset(&challenge, 0xff, sizeof(challenge));
218 memset(&rp_id_hash, 0, sizeof(rp_id_hash));
219
220 if (SHA256((const void *)rp_id, strlen(rp_id),
221 rp_id_hash) != rp_id_hash) {
222 fido_log_debug("%s: sha256", __func__);
223 r = FIDO_ERR_INTERNAL;
224 goto fail;
225 }
226
227 key_id_len = (uint8_t)key_id->len;
228
229 if ((apdu = iso7816_new(0, U2F_CMD_AUTH, U2F_AUTH_CHECK, (uint16_t)(2 *
230 SHA256_DIGEST_LENGTH + sizeof(key_id_len) + key_id_len))) == NULL ||
231 iso7816_add(apdu, &challenge, sizeof(challenge)) < 0 ||
232 iso7816_add(apdu, &rp_id_hash, sizeof(rp_id_hash)) < 0 ||
233 iso7816_add(apdu, &key_id_len, sizeof(key_id_len)) < 0 ||
234 iso7816_add(apdu, key_id->ptr, key_id_len) < 0) {
235 fido_log_debug("%s: iso7816", __func__);
236 r = FIDO_ERR_INTERNAL;
237 goto fail;
238 }
239
240 if ((reply = malloc(FIDO_MAXMSG)) == NULL) {
241 fido_log_debug("%s: malloc", __func__);
242 r = FIDO_ERR_INTERNAL;
243 goto fail;
244 }
245
246 if (fido_tx(dev, CTAP_CMD_MSG, iso7816_ptr(apdu),
247 iso7816_len(apdu), ms) < 0) {
248 fido_log_debug("%s: fido_tx", __func__);
249 r = FIDO_ERR_TX;
250 goto fail;
251 }
252 if (fido_rx(dev, CTAP_CMD_MSG, reply, FIDO_MAXMSG, ms) != 2) {
253 fido_log_debug("%s: fido_rx", __func__);
254 r = FIDO_ERR_RX;
255 goto fail;
256 }
257
258 switch ((reply[0] << 8) | reply[1]) {
259 case SW_CONDITIONS_NOT_SATISFIED:
260 *found = 1; /* key exists */
261 break;
262 case SW_WRONG_DATA:
263 *found = 0; /* key does not exist */
264 break;
265 default:
266 /* unexpected sw */
267 r = FIDO_ERR_INTERNAL;
268 goto fail;
269 }
270
271 r = FIDO_OK;
272 fail:
273 iso7816_free(&apdu);
274 freezero(reply, FIDO_MAXMSG);
275
276 return (r);
277 }
278
279 static int
parse_auth_reply(fido_blob_t * sig,fido_blob_t * ad,const char * rp_id,const unsigned char * reply,size_t len)280 parse_auth_reply(fido_blob_t *sig, fido_blob_t *ad, const char *rp_id,
281 const unsigned char *reply, size_t len)
282 {
283 uint8_t flags;
284 uint32_t sigcount;
285
286 if (len < 2 || ((reply[len - 2] << 8) | reply[len - 1]) != SW_NO_ERROR) {
287 fido_log_debug("%s: unexpected sw", __func__);
288 return (FIDO_ERR_RX);
289 }
290
291 len -= 2;
292
293 if (fido_buf_read(&reply, &len, &flags, sizeof(flags)) < 0 ||
294 fido_buf_read(&reply, &len, &sigcount, sizeof(sigcount)) < 0) {
295 fido_log_debug("%s: fido_buf_read", __func__);
296 return (FIDO_ERR_RX);
297 }
298
299 if (sig_get(sig, &reply, &len) < 0) {
300 fido_log_debug("%s: sig_get", __func__);
301 return (FIDO_ERR_RX);
302 }
303
304 if (authdata_fake(rp_id, flags, sigcount, ad) < 0) {
305 fido_log_debug("%s; authdata_fake", __func__);
306 return (FIDO_ERR_RX);
307 }
308
309 return (FIDO_OK);
310 }
311
312 static int
do_auth(fido_dev_t * dev,const fido_blob_t * cdh,const char * rp_id,const fido_blob_t * key_id,fido_blob_t * sig,fido_blob_t * ad,int * ms)313 do_auth(fido_dev_t *dev, const fido_blob_t *cdh, const char *rp_id,
314 const fido_blob_t *key_id, fido_blob_t *sig, fido_blob_t *ad, int *ms)
315 {
316 iso7816_apdu_t *apdu = NULL;
317 unsigned char *reply = NULL;
318 unsigned char rp_id_hash[SHA256_DIGEST_LENGTH];
319 int reply_len;
320 uint8_t key_id_len;
321 int r;
322
323 #ifdef FIDO_FUZZ
324 *ms = 0; /* XXX */
325 #endif
326
327 if (cdh->len != SHA256_DIGEST_LENGTH || key_id->len > UINT8_MAX ||
328 rp_id == NULL) {
329 r = FIDO_ERR_INVALID_ARGUMENT;
330 goto fail;
331 }
332
333 memset(&rp_id_hash, 0, sizeof(rp_id_hash));
334
335 if (SHA256((const void *)rp_id, strlen(rp_id),
336 rp_id_hash) != rp_id_hash) {
337 fido_log_debug("%s: sha256", __func__);
338 r = FIDO_ERR_INTERNAL;
339 goto fail;
340 }
341
342 key_id_len = (uint8_t)key_id->len;
343
344 if ((apdu = iso7816_new(0, U2F_CMD_AUTH, U2F_AUTH_SIGN, (uint16_t)(2 *
345 SHA256_DIGEST_LENGTH + sizeof(key_id_len) + key_id_len))) == NULL ||
346 iso7816_add(apdu, cdh->ptr, cdh->len) < 0 ||
347 iso7816_add(apdu, &rp_id_hash, sizeof(rp_id_hash)) < 0 ||
348 iso7816_add(apdu, &key_id_len, sizeof(key_id_len)) < 0 ||
349 iso7816_add(apdu, key_id->ptr, key_id_len) < 0) {
350 fido_log_debug("%s: iso7816", __func__);
351 r = FIDO_ERR_INTERNAL;
352 goto fail;
353 }
354
355 if ((reply = malloc(FIDO_MAXMSG)) == NULL) {
356 fido_log_debug("%s: malloc", __func__);
357 r = FIDO_ERR_INTERNAL;
358 goto fail;
359 }
360
361 do {
362 if (fido_tx(dev, CTAP_CMD_MSG, iso7816_ptr(apdu),
363 iso7816_len(apdu), ms) < 0) {
364 fido_log_debug("%s: fido_tx", __func__);
365 r = FIDO_ERR_TX;
366 goto fail;
367 }
368 if ((reply_len = fido_rx(dev, CTAP_CMD_MSG, reply,
369 FIDO_MAXMSG, ms)) < 2) {
370 fido_log_debug("%s: fido_rx", __func__);
371 r = FIDO_ERR_RX;
372 goto fail;
373 }
374 if (delay_ms(U2F_PACE_MS, ms) != 0) {
375 fido_log_debug("%s: delay_ms", __func__);
376 r = FIDO_ERR_RX;
377 goto fail;
378 }
379 } while (((reply[0] << 8) | reply[1]) == SW_CONDITIONS_NOT_SATISFIED);
380
381 if ((r = parse_auth_reply(sig, ad, rp_id, reply,
382 (size_t)reply_len)) != FIDO_OK) {
383 fido_log_debug("%s: parse_auth_reply", __func__);
384 goto fail;
385 }
386
387 fail:
388 iso7816_free(&apdu);
389 freezero(reply, FIDO_MAXMSG);
390
391 return (r);
392 }
393
394 static int
cbor_blob_from_ec_point(const uint8_t * ec_point,size_t ec_point_len,fido_blob_t * cbor_blob)395 cbor_blob_from_ec_point(const uint8_t *ec_point, size_t ec_point_len,
396 fido_blob_t *cbor_blob)
397 {
398 es256_pk_t *pk = NULL;
399 cbor_item_t *pk_cbor = NULL;
400 size_t alloc_len;
401 int ok = -1;
402
403 /* only handle uncompressed points */
404 if (ec_point_len != 65 || ec_point[0] != 0x04) {
405 fido_log_debug("%s: unexpected format", __func__);
406 goto fail;
407 }
408
409 if ((pk = es256_pk_new()) == NULL ||
410 es256_pk_set_x(pk, &ec_point[1]) < 0 ||
411 es256_pk_set_y(pk, &ec_point[33]) < 0) {
412 fido_log_debug("%s: es256_pk_set", __func__);
413 goto fail;
414 }
415
416 if ((pk_cbor = es256_pk_encode(pk, 0)) == NULL) {
417 fido_log_debug("%s: es256_pk_encode", __func__);
418 goto fail;
419 }
420
421 if ((cbor_blob->len = cbor_serialize_alloc(pk_cbor, &cbor_blob->ptr,
422 &alloc_len)) != 77) {
423 fido_log_debug("%s: cbor_serialize_alloc", __func__);
424 goto fail;
425 }
426
427 ok = 0;
428 fail:
429 es256_pk_free(&pk);
430
431 if (pk_cbor)
432 cbor_decref(&pk_cbor);
433
434 return (ok);
435 }
436
437 static int
encode_cred_attstmt(int cose_alg,const fido_blob_t * x5c,const fido_blob_t * sig,fido_blob_t * out)438 encode_cred_attstmt(int cose_alg, const fido_blob_t *x5c,
439 const fido_blob_t *sig, fido_blob_t *out)
440 {
441 cbor_item_t *item = NULL;
442 cbor_item_t *x5c_cbor = NULL;
443 const uint8_t alg_cbor = (uint8_t)(-cose_alg - 1);
444 struct cbor_pair kv[3];
445 size_t alloc_len;
446 int ok = -1;
447
448 memset(&kv, 0, sizeof(kv));
449 memset(out, 0, sizeof(*out));
450
451 if ((item = cbor_new_definite_map(3)) == NULL) {
452 fido_log_debug("%s: cbor_new_definite_map", __func__);
453 goto fail;
454 }
455
456 if ((kv[0].key = cbor_build_string("alg")) == NULL ||
457 (kv[0].value = cbor_build_negint8(alg_cbor)) == NULL ||
458 !cbor_map_add(item, kv[0])) {
459 fido_log_debug("%s: alg", __func__);
460 goto fail;
461 }
462
463 if ((kv[1].key = cbor_build_string("sig")) == NULL ||
464 (kv[1].value = fido_blob_encode(sig)) == NULL ||
465 !cbor_map_add(item, kv[1])) {
466 fido_log_debug("%s: sig", __func__);
467 goto fail;
468 }
469
470 if ((kv[2].key = cbor_build_string("x5c")) == NULL ||
471 (kv[2].value = cbor_new_definite_array(1)) == NULL ||
472 (x5c_cbor = fido_blob_encode(x5c)) == NULL ||
473 !cbor_array_push(kv[2].value, x5c_cbor) ||
474 !cbor_map_add(item, kv[2])) {
475 fido_log_debug("%s: x5c", __func__);
476 goto fail;
477 }
478
479 if ((out->len = cbor_serialize_alloc(item, &out->ptr,
480 &alloc_len)) == 0) {
481 fido_log_debug("%s: cbor_serialize_alloc", __func__);
482 goto fail;
483 }
484
485 ok = 0;
486 fail:
487 if (item != NULL)
488 cbor_decref(&item);
489 if (x5c_cbor != NULL)
490 cbor_decref(&x5c_cbor);
491
492 for (size_t i = 0; i < nitems(kv); i++) {
493 if (kv[i].key)
494 cbor_decref(&kv[i].key);
495 if (kv[i].value)
496 cbor_decref(&kv[i].value);
497 }
498
499 return (ok);
500 }
501
502 static int
encode_cred_authdata(const char * rp_id,const uint8_t * kh,uint8_t kh_len,const uint8_t * pubkey,size_t pubkey_len,fido_blob_t * out)503 encode_cred_authdata(const char *rp_id, const uint8_t *kh, uint8_t kh_len,
504 const uint8_t *pubkey, size_t pubkey_len, fido_blob_t *out)
505 {
506 fido_authdata_t authdata;
507 fido_attcred_raw_t attcred_raw;
508 fido_blob_t pk_blob;
509 fido_blob_t authdata_blob;
510 cbor_item_t *authdata_cbor = NULL;
511 unsigned char *ptr;
512 size_t len;
513 size_t alloc_len;
514 int ok = -1;
515
516 memset(&pk_blob, 0, sizeof(pk_blob));
517 memset(&authdata, 0, sizeof(authdata));
518 memset(&authdata_blob, 0, sizeof(authdata_blob));
519 memset(out, 0, sizeof(*out));
520
521 if (rp_id == NULL) {
522 fido_log_debug("%s: NULL rp_id", __func__);
523 goto fail;
524 }
525
526 if (cbor_blob_from_ec_point(pubkey, pubkey_len, &pk_blob) < 0) {
527 fido_log_debug("%s: cbor_blob_from_ec_point", __func__);
528 goto fail;
529 }
530
531 if (SHA256((const void *)rp_id, strlen(rp_id),
532 authdata.rp_id_hash) != authdata.rp_id_hash) {
533 fido_log_debug("%s: sha256", __func__);
534 goto fail;
535 }
536
537 authdata.flags = (CTAP_AUTHDATA_ATT_CRED | CTAP_AUTHDATA_USER_PRESENT);
538 authdata.sigcount = 0;
539
540 memset(&attcred_raw.aaguid, 0, sizeof(attcred_raw.aaguid));
541 attcred_raw.id_len = htobe16(kh_len);
542
543 len = authdata_blob.len = sizeof(authdata) + sizeof(attcred_raw) +
544 kh_len + pk_blob.len;
545 ptr = authdata_blob.ptr = calloc(1, authdata_blob.len);
546
547 fido_log_debug("%s: ptr=%p, len=%zu", __func__, (void *)ptr, len);
548
549 if (authdata_blob.ptr == NULL)
550 goto fail;
551
552 if (fido_buf_write(&ptr, &len, &authdata, sizeof(authdata)) < 0 ||
553 fido_buf_write(&ptr, &len, &attcred_raw, sizeof(attcred_raw)) < 0 ||
554 fido_buf_write(&ptr, &len, kh, kh_len) < 0 ||
555 fido_buf_write(&ptr, &len, pk_blob.ptr, pk_blob.len) < 0) {
556 fido_log_debug("%s: fido_buf_write", __func__);
557 goto fail;
558 }
559
560 if ((authdata_cbor = fido_blob_encode(&authdata_blob)) == NULL) {
561 fido_log_debug("%s: fido_blob_encode", __func__);
562 goto fail;
563 }
564
565 if ((out->len = cbor_serialize_alloc(authdata_cbor, &out->ptr,
566 &alloc_len)) == 0) {
567 fido_log_debug("%s: cbor_serialize_alloc", __func__);
568 goto fail;
569 }
570
571 ok = 0;
572 fail:
573 if (authdata_cbor)
574 cbor_decref(&authdata_cbor);
575
576 fido_blob_reset(&pk_blob);
577 fido_blob_reset(&authdata_blob);
578
579 return (ok);
580 }
581
582 static int
parse_register_reply(fido_cred_t * cred,const unsigned char * reply,size_t len)583 parse_register_reply(fido_cred_t *cred, const unsigned char *reply, size_t len)
584 {
585 fido_blob_t x5c;
586 fido_blob_t sig;
587 fido_blob_t ad;
588 fido_blob_t stmt;
589 uint8_t dummy;
590 uint8_t pubkey[65];
591 uint8_t kh_len = 0;
592 uint8_t *kh = NULL;
593 int r;
594
595 memset(&x5c, 0, sizeof(x5c));
596 memset(&sig, 0, sizeof(sig));
597 memset(&ad, 0, sizeof(ad));
598 memset(&stmt, 0, sizeof(stmt));
599 r = FIDO_ERR_RX;
600
601 /* status word */
602 if (len < 2 || ((reply[len - 2] << 8) | reply[len - 1]) != SW_NO_ERROR) {
603 fido_log_debug("%s: unexpected sw", __func__);
604 goto fail;
605 }
606
607 len -= 2;
608
609 /* reserved byte */
610 if (fido_buf_read(&reply, &len, &dummy, sizeof(dummy)) < 0 ||
611 dummy != 0x05) {
612 fido_log_debug("%s: reserved byte", __func__);
613 goto fail;
614 }
615
616 /* pubkey + key handle */
617 if (fido_buf_read(&reply, &len, &pubkey, sizeof(pubkey)) < 0 ||
618 fido_buf_read(&reply, &len, &kh_len, sizeof(kh_len)) < 0 ||
619 (kh = calloc(1, kh_len)) == NULL ||
620 fido_buf_read(&reply, &len, kh, kh_len) < 0) {
621 fido_log_debug("%s: fido_buf_read", __func__);
622 goto fail;
623 }
624
625 /* x5c + sig */
626 if (x5c_get(&x5c, &reply, &len) < 0 ||
627 sig_get(&sig, &reply, &len) < 0) {
628 fido_log_debug("%s: x5c || sig", __func__);
629 goto fail;
630 }
631
632 /* attstmt */
633 if (encode_cred_attstmt(COSE_ES256, &x5c, &sig, &stmt) < 0) {
634 fido_log_debug("%s: encode_cred_attstmt", __func__);
635 goto fail;
636 }
637
638 /* authdata */
639 if (encode_cred_authdata(cred->rp.id, kh, kh_len, pubkey,
640 sizeof(pubkey), &ad) < 0) {
641 fido_log_debug("%s: encode_cred_authdata", __func__);
642 goto fail;
643 }
644
645 if (fido_cred_set_fmt(cred, "fido-u2f") != FIDO_OK ||
646 fido_cred_set_authdata(cred, ad.ptr, ad.len) != FIDO_OK ||
647 fido_cred_set_attstmt(cred, stmt.ptr, stmt.len) != FIDO_OK) {
648 fido_log_debug("%s: fido_cred_set", __func__);
649 r = FIDO_ERR_INTERNAL;
650 goto fail;
651 }
652
653 r = FIDO_OK;
654 fail:
655 freezero(kh, kh_len);
656 fido_blob_reset(&x5c);
657 fido_blob_reset(&sig);
658 fido_blob_reset(&ad);
659 fido_blob_reset(&stmt);
660
661 return (r);
662 }
663
664 int
u2f_register(fido_dev_t * dev,fido_cred_t * cred,int * ms)665 u2f_register(fido_dev_t *dev, fido_cred_t *cred, int *ms)
666 {
667 iso7816_apdu_t *apdu = NULL;
668 unsigned char rp_id_hash[SHA256_DIGEST_LENGTH];
669 unsigned char *reply = NULL;
670 int reply_len;
671 int found;
672 int r;
673
674 if (cred->rk == FIDO_OPT_TRUE || cred->uv == FIDO_OPT_TRUE) {
675 fido_log_debug("%s: rk=%d, uv=%d", __func__, cred->rk,
676 cred->uv);
677 return (FIDO_ERR_UNSUPPORTED_OPTION);
678 }
679
680 if (cred->type != COSE_ES256 || cred->cdh.ptr == NULL ||
681 cred->rp.id == NULL || cred->cdh.len != SHA256_DIGEST_LENGTH) {
682 fido_log_debug("%s: type=%d, cdh=(%p,%zu)" , __func__,
683 cred->type, (void *)cred->cdh.ptr, cred->cdh.len);
684 return (FIDO_ERR_INVALID_ARGUMENT);
685 }
686
687 for (size_t i = 0; i < cred->excl.len; i++) {
688 if ((r = key_lookup(dev, cred->rp.id, &cred->excl.ptr[i],
689 &found, ms)) != FIDO_OK) {
690 fido_log_debug("%s: key_lookup", __func__);
691 return (r);
692 }
693 if (found) {
694 if ((r = send_dummy_register(dev, ms)) != FIDO_OK) {
695 fido_log_debug("%s: send_dummy_register",
696 __func__);
697 return (r);
698 }
699 return (FIDO_ERR_CREDENTIAL_EXCLUDED);
700 }
701 }
702
703 memset(&rp_id_hash, 0, sizeof(rp_id_hash));
704
705 if (SHA256((const void *)cred->rp.id, strlen(cred->rp.id),
706 rp_id_hash) != rp_id_hash) {
707 fido_log_debug("%s: sha256", __func__);
708 return (FIDO_ERR_INTERNAL);
709 }
710
711 if ((apdu = iso7816_new(0, U2F_CMD_REGISTER, 0, 2 *
712 SHA256_DIGEST_LENGTH)) == NULL ||
713 iso7816_add(apdu, cred->cdh.ptr, cred->cdh.len) < 0 ||
714 iso7816_add(apdu, rp_id_hash, sizeof(rp_id_hash)) < 0) {
715 fido_log_debug("%s: iso7816", __func__);
716 r = FIDO_ERR_INTERNAL;
717 goto fail;
718 }
719
720 if ((reply = malloc(FIDO_MAXMSG)) == NULL) {
721 fido_log_debug("%s: malloc", __func__);
722 r = FIDO_ERR_INTERNAL;
723 goto fail;
724 }
725
726 do {
727 if (fido_tx(dev, CTAP_CMD_MSG, iso7816_ptr(apdu),
728 iso7816_len(apdu), ms) < 0) {
729 fido_log_debug("%s: fido_tx", __func__);
730 r = FIDO_ERR_TX;
731 goto fail;
732 }
733 if ((reply_len = fido_rx(dev, CTAP_CMD_MSG, reply,
734 FIDO_MAXMSG, ms)) < 2) {
735 fido_log_debug("%s: fido_rx", __func__);
736 r = FIDO_ERR_RX;
737 goto fail;
738 }
739 if (delay_ms(U2F_PACE_MS, ms) != 0) {
740 fido_log_debug("%s: delay_ms", __func__);
741 r = FIDO_ERR_RX;
742 goto fail;
743 }
744 } while (((reply[0] << 8) | reply[1]) == SW_CONDITIONS_NOT_SATISFIED);
745
746 if ((r = parse_register_reply(cred, reply,
747 (size_t)reply_len)) != FIDO_OK) {
748 fido_log_debug("%s: parse_register_reply", __func__);
749 goto fail;
750 }
751 fail:
752 iso7816_free(&apdu);
753 freezero(reply, FIDO_MAXMSG);
754
755 return (r);
756 }
757
758 static int
u2f_authenticate_single(fido_dev_t * dev,const fido_blob_t * key_id,fido_assert_t * fa,size_t idx,int * ms)759 u2f_authenticate_single(fido_dev_t *dev, const fido_blob_t *key_id,
760 fido_assert_t *fa, size_t idx, int *ms)
761 {
762 fido_blob_t sig;
763 fido_blob_t ad;
764 int found;
765 int r;
766
767 memset(&sig, 0, sizeof(sig));
768 memset(&ad, 0, sizeof(ad));
769
770 if ((r = key_lookup(dev, fa->rp_id, key_id, &found, ms)) != FIDO_OK) {
771 fido_log_debug("%s: key_lookup", __func__);
772 goto fail;
773 }
774
775 if (!found) {
776 fido_log_debug("%s: not found", __func__);
777 r = FIDO_ERR_CREDENTIAL_EXCLUDED;
778 goto fail;
779 }
780
781 if (fido_blob_set(&fa->stmt[idx].id, key_id->ptr, key_id->len) < 0) {
782 fido_log_debug("%s: fido_blob_set", __func__);
783 r = FIDO_ERR_INTERNAL;
784 goto fail;
785 }
786
787 if (fa->up == FIDO_OPT_FALSE) {
788 fido_log_debug("%s: checking for key existence only", __func__);
789 r = FIDO_ERR_USER_PRESENCE_REQUIRED;
790 goto fail;
791 }
792
793 if ((r = do_auth(dev, &fa->cdh, fa->rp_id, key_id, &sig, &ad,
794 ms)) != FIDO_OK) {
795 fido_log_debug("%s: do_auth", __func__);
796 goto fail;
797 }
798
799 if (fido_assert_set_authdata(fa, idx, ad.ptr, ad.len) != FIDO_OK ||
800 fido_assert_set_sig(fa, idx, sig.ptr, sig.len) != FIDO_OK) {
801 fido_log_debug("%s: fido_assert_set", __func__);
802 r = FIDO_ERR_INTERNAL;
803 goto fail;
804 }
805
806 r = FIDO_OK;
807 fail:
808 fido_blob_reset(&sig);
809 fido_blob_reset(&ad);
810
811 return (r);
812 }
813
814 int
u2f_authenticate(fido_dev_t * dev,fido_assert_t * fa,int * ms)815 u2f_authenticate(fido_dev_t *dev, fido_assert_t *fa, int *ms)
816 {
817 size_t nfound = 0;
818 size_t nauth_ok = 0;
819 int r;
820
821 if (fa->uv == FIDO_OPT_TRUE || fa->allow_list.ptr == NULL) {
822 fido_log_debug("%s: uv=%d, allow_list=%p", __func__, fa->uv,
823 (void *)fa->allow_list.ptr);
824 return (FIDO_ERR_UNSUPPORTED_OPTION);
825 }
826
827 if ((r = fido_assert_set_count(fa, fa->allow_list.len)) != FIDO_OK) {
828 fido_log_debug("%s: fido_assert_set_count", __func__);
829 return (r);
830 }
831
832 for (size_t i = 0; i < fa->allow_list.len; i++) {
833 switch ((r = u2f_authenticate_single(dev,
834 &fa->allow_list.ptr[i], fa, nfound, ms))) {
835 case FIDO_OK:
836 nauth_ok++;
837 FALLTHROUGH
838 case FIDO_ERR_USER_PRESENCE_REQUIRED:
839 nfound++;
840 break;
841 default:
842 if (r != FIDO_ERR_CREDENTIAL_EXCLUDED) {
843 fido_log_debug("%s: u2f_authenticate_single",
844 __func__);
845 return (r);
846 }
847 /* ignore credentials that don't exist */
848 }
849 }
850
851 fa->stmt_len = nfound;
852
853 if (nfound == 0)
854 return (FIDO_ERR_NO_CREDENTIALS);
855 if (nauth_ok == 0)
856 return (FIDO_ERR_USER_PRESENCE_REQUIRED);
857
858 return (FIDO_OK);
859 }
860
861 int
u2f_get_touch_begin(fido_dev_t * dev,int * ms)862 u2f_get_touch_begin(fido_dev_t *dev, int *ms)
863 {
864 iso7816_apdu_t *apdu = NULL;
865 const char *clientdata = FIDO_DUMMY_CLIENTDATA;
866 const char *rp_id = FIDO_DUMMY_RP_ID;
867 unsigned char *reply = NULL;
868 unsigned char clientdata_hash[SHA256_DIGEST_LENGTH];
869 unsigned char rp_id_hash[SHA256_DIGEST_LENGTH];
870 int r;
871
872 memset(&clientdata_hash, 0, sizeof(clientdata_hash));
873 memset(&rp_id_hash, 0, sizeof(rp_id_hash));
874
875 if (SHA256((const void *)clientdata, strlen(clientdata),
876 clientdata_hash) != clientdata_hash || SHA256((const void *)rp_id,
877 strlen(rp_id), rp_id_hash) != rp_id_hash) {
878 fido_log_debug("%s: sha256", __func__);
879 return (FIDO_ERR_INTERNAL);
880 }
881
882 if ((apdu = iso7816_new(0, U2F_CMD_REGISTER, 0, 2 *
883 SHA256_DIGEST_LENGTH)) == NULL ||
884 iso7816_add(apdu, clientdata_hash, sizeof(clientdata_hash)) < 0 ||
885 iso7816_add(apdu, rp_id_hash, sizeof(rp_id_hash)) < 0) {
886 fido_log_debug("%s: iso7816", __func__);
887 r = FIDO_ERR_INTERNAL;
888 goto fail;
889 }
890
891 if ((reply = malloc(FIDO_MAXMSG)) == NULL) {
892 fido_log_debug("%s: malloc", __func__);
893 r = FIDO_ERR_INTERNAL;
894 goto fail;
895 }
896
897 if (dev->attr.flags & FIDO_CAP_WINK) {
898 fido_tx(dev, CTAP_CMD_WINK, NULL, 0, ms);
899 fido_rx(dev, CTAP_CMD_WINK, reply, FIDO_MAXMSG, ms);
900 }
901
902 if (fido_tx(dev, CTAP_CMD_MSG, iso7816_ptr(apdu),
903 iso7816_len(apdu), ms) < 0) {
904 fido_log_debug("%s: fido_tx", __func__);
905 r = FIDO_ERR_TX;
906 goto fail;
907 }
908
909 r = FIDO_OK;
910 fail:
911 iso7816_free(&apdu);
912 freezero(reply, FIDO_MAXMSG);
913
914 return (r);
915 }
916
917 int
u2f_get_touch_status(fido_dev_t * dev,int * touched,int * ms)918 u2f_get_touch_status(fido_dev_t *dev, int *touched, int *ms)
919 {
920 unsigned char *reply;
921 int reply_len;
922 int r;
923
924 if ((reply = malloc(FIDO_MAXMSG)) == NULL) {
925 fido_log_debug("%s: malloc", __func__);
926 r = FIDO_ERR_INTERNAL;
927 goto out;
928 }
929
930 if ((reply_len = fido_rx(dev, CTAP_CMD_MSG, reply, FIDO_MAXMSG,
931 ms)) < 2) {
932 fido_log_debug("%s: fido_rx", __func__);
933 r = FIDO_OK; /* ignore */
934 goto out;
935 }
936
937 switch ((reply[reply_len - 2] << 8) | reply[reply_len - 1]) {
938 case SW_CONDITIONS_NOT_SATISFIED:
939 if ((r = u2f_get_touch_begin(dev, ms)) != FIDO_OK) {
940 fido_log_debug("%s: u2f_get_touch_begin", __func__);
941 goto out;
942 }
943 *touched = 0;
944 break;
945 case SW_NO_ERROR:
946 *touched = 1;
947 break;
948 default:
949 fido_log_debug("%s: unexpected sw", __func__);
950 r = FIDO_ERR_RX;
951 goto out;
952 }
953
954 r = FIDO_OK;
955 out:
956 freezero(reply, FIDO_MAXMSG);
957
958 return (r);
959 }
960