summaryrefslogtreecommitdiff
path: root/regress/misc/sk-dummy/sk-dummy.c
blob: 928d556b9bad2a1fe930336f4236b980488ac4f8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
/*
 * Copyright (c) 2019 Markus Friedl
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "includes.h"

#ifdef HAVE_STDINT_H
#include <stdint.h>
#endif
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <stddef.h>
#include <stdarg.h>
#ifdef HAVE_SHA2_H
#include <sha2.h>
#endif

#include "crypto_api.h"
#include "sk-api.h"

#if defined(WITH_OPENSSL) && !defined(OPENSSL_HAS_ECC)
# undef WITH_OPENSSL
#endif

#ifdef WITH_OPENSSL
#include <openssl/opensslv.h>
#include <openssl/crypto.h>
#include <openssl/evp.h>
#include <openssl/bn.h>
#include <openssl/ec.h>
#include <openssl/ecdsa.h>
#include <openssl/pem.h>

/* Compatibility with OpenSSH 1.0.x */
#if (OPENSSL_VERSION_NUMBER < 0x10100000L)
#define ECDSA_SIG_get0(sig, pr, ps) \
	do { \
		(*pr) = sig->r; \
		(*ps) = sig->s; \
	} while (0)
#endif
#endif /* WITH_OPENSSL */

/* #define SK_DEBUG 1 */

#if SSH_SK_VERSION_MAJOR != 0x00070000
# error SK API has changed, sk-dummy.c needs an update
#endif

#ifdef SK_DUMMY_INTEGRATE
# define sk_api_version		ssh_sk_api_version
# define sk_enroll		ssh_sk_enroll
# define sk_sign		ssh_sk_sign
# define sk_load_resident_keys	ssh_sk_load_resident_keys
#endif /* !SK_STANDALONE */

static void skdebug(const char *func, const char *fmt, ...)
    __attribute__((__format__ (printf, 2, 3)));

static void
skdebug(const char *func, const char *fmt, ...)
{
#if defined(SK_DEBUG)
	va_list ap;

	va_start(ap, fmt);
	fprintf(stderr, "sk-dummy %s: ", func);
	vfprintf(stderr, fmt, ap);
	fputc('\n', stderr);
	va_end(ap);
#else
	(void)func; /* XXX */
	(void)fmt; /* XXX */
#endif
}

uint32_t
sk_api_version(void)
{
	return SSH_SK_VERSION_MAJOR;
}

static int
pack_key_ecdsa(struct sk_enroll_response *response)
{
#ifdef OPENSSL_HAS_ECC
	EC_KEY *key = NULL;
	const EC_GROUP *g;
	const EC_POINT *q;
	int ret = -1;
	long privlen;
	BIO *bio = NULL;
	char *privptr;

	response->public_key = NULL;
	response->public_key_len = 0;
	response->key_handle = NULL;
	response->key_handle_len = 0;

	if ((key = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1)) == NULL) {
		skdebug(__func__, "EC_KEY_new_by_curve_name");
		goto out;
	}
	if (EC_KEY_generate_key(key) != 1) {
		skdebug(__func__, "EC_KEY_generate_key");
		goto out;
	}
	EC_KEY_set_asn1_flag(key, OPENSSL_EC_NAMED_CURVE);
	if ((bio = BIO_new(BIO_s_mem())) == NULL ||
	    (g = EC_KEY_get0_group(key)) == NULL ||
	    (q = EC_KEY_get0_public_key(key)) == NULL) {
		skdebug(__func__, "couldn't get key parameters");
		goto out;
	}
	response->public_key_len = EC_POINT_point2oct(g, q,
	    POINT_CONVERSION_UNCOMPRESSED, NULL, 0, NULL);
	if (response->public_key_len == 0 || response->public_key_len > 2048) {
		skdebug(__func__, "bad pubkey length %zu",
		    response->public_key_len);
		goto out;
	}
	if ((response->public_key = malloc(response->public_key_len)) == NULL) {
		skdebug(__func__, "malloc pubkey failed");
		goto out;
	}
	if (EC_POINT_point2oct(g, q, POINT_CONVERSION_UNCOMPRESSED,
	    response->public_key, response->public_key_len, NULL) == 0) {
		skdebug(__func__, "EC_POINT_point2oct failed");
		goto out;
	}
	/* Key handle contains PEM encoded private key */
	if (!PEM_write_bio_ECPrivateKey(bio, key, NULL, NULL, 0, NULL, NULL)) {
		skdebug(__func__, "PEM_write_bio_ECPrivateKey failed");
		goto out;
	}
	if ((privlen = BIO_get_mem_data(bio, &privptr)) <= 0) {
		skdebug(__func__, "BIO_get_mem_data failed");
		goto out;
	}
	if ((response->key_handle = malloc(privlen)) == NULL) {
		skdebug(__func__, "malloc key_handle failed");
		goto out;
	}
	response->key_handle_len = (size_t)privlen;
	memcpy(response->key_handle, privptr, response->key_handle_len);
	/* success */
	ret = 0;
 out:
	if (ret != 0) {
		if (response->public_key != NULL) {
			memset(response->public_key, 0,
			    response->public_key_len);
			free(response->public_key);
			response->public_key = NULL;
		}
		if (response->key_handle != NULL) {
			memset(response->key_handle, 0,
			    response->key_handle_len);
			free(response->key_handle);
			response->key_handle = NULL;
		}
	}
	BIO_free(bio);
	EC_KEY_free(key);
	return ret;
#else
	return -1;
#endif
}

static int
pack_key_ed25519(struct sk_enroll_response *response)
{
	int ret = -1;
	u_char pk[crypto_sign_ed25519_PUBLICKEYBYTES];
	u_char sk[crypto_sign_ed25519_SECRETKEYBYTES];

	response->public_key = NULL;
	response->public_key_len = 0;
	response->key_handle = NULL;
	response->key_handle_len = 0;

	memset(pk, 0, sizeof(pk));
	memset(sk, 0, sizeof(sk));
	crypto_sign_ed25519_keypair(pk, sk);

	response->public_key_len = sizeof(pk);
	if ((response->public_key = malloc(response->public_key_len)) == NULL) {
		skdebug(__func__, "malloc pubkey failed");
		goto out;
	}
	memcpy(response->public_key, pk, sizeof(pk));
	/* Key handle contains sk */
	response->key_handle_len = sizeof(sk);
	if ((response->key_handle = malloc(response->key_handle_len)) == NULL) {
		skdebug(__func__, "malloc key_handle failed");
		goto out;
	}
	memcpy(response->key_handle, sk, sizeof(sk));
	/* success */
	ret = 0;
 out:
	if (ret != 0)
		free(response->public_key);
	return ret;
}

static int
check_options(struct sk_option **options)
{
	size_t i;

	if (options == NULL)
		return 0;
	for (i = 0; options[i] != NULL; i++) {
		skdebug(__func__, "requested unsupported option %s",
		    options[i]->name);
		if (options[i]->required) {
			skdebug(__func__, "unknown required option");
			return -1;
		}
	}
	return 0;
}

int
sk_enroll(uint32_t alg, const uint8_t *challenge, size_t challenge_len,
    const char *application, uint8_t flags, const char *pin,
    struct sk_option **options, struct sk_enroll_response **enroll_response)
{
	struct sk_enroll_response *response = NULL;
	int ret = SSH_SK_ERR_GENERAL;

	(void)flags; /* XXX; unused */

	if (enroll_response == NULL) {
		skdebug(__func__, "enroll_response == NULL");
		goto out;
	}
	*enroll_response = NULL;
	if (check_options(options) != 0)
		goto out; /* error already logged */
	if ((response = calloc(1, sizeof(*response))) == NULL) {
		skdebug(__func__, "calloc response failed");
		goto out;
	}
	switch(alg) {
	case SSH_SK_ECDSA:
		if (pack_key_ecdsa(response) != 0)
			goto out;
		break;
	case SSH_SK_ED25519:
		if (pack_key_ed25519(response) != 0)
			goto out;
		break;
	default:
		skdebug(__func__, "unsupported key type %d", alg);
		return -1;
	}
	/* Have to return something here */
	if ((response->signature = calloc(1, 1)) == NULL) {
		skdebug(__func__, "calloc signature failed");
		goto out;
	}
	response->signature_len = 0;

	*enroll_response = response;
	response = NULL;
	ret = 0;
 out:
	if (response != NULL) {
		free(response->public_key);
		free(response->key_handle);
		free(response->signature);
		free(response->attestation_cert);
		free(response);
	}
	return ret;
}

static void
dump(const char *preamble, const void *sv, size_t l)
{
#ifdef SK_DEBUG
	const u_char *s = (const u_char *)sv;
	size_t i;

	fprintf(stderr, "%s (len %zu):\n", preamble, l);
	for (i = 0; i < l; i++) {
		if (i % 16 == 0)
			fprintf(stderr, "%04zu: ", i);
		fprintf(stderr, "%02x", s[i]);
		if (i % 16 == 15 || i == l - 1)
			fprintf(stderr, "\n");
	}
#endif
}

static int
sig_ecdsa(const uint8_t *message, size_t message_len,
    const char *application, uint32_t counter, uint8_t flags,
    const uint8_t *key_handle, size_t key_handle_len,
    struct sk_sign_response *response)
{
#ifdef OPENSSL_HAS_ECC
	ECDSA_SIG *sig = NULL;
	const BIGNUM *sig_r, *sig_s;
	int ret = -1;
	BIO *bio = NULL;
	EVP_PKEY *pk = NULL;
	EC_KEY *ec = NULL;
	SHA2_CTX ctx;
	uint8_t	apphash[SHA256_DIGEST_LENGTH];
	uint8_t	sighash[SHA256_DIGEST_LENGTH];
	uint8_t countbuf[4];

	/* Decode EC_KEY from key handle */
	if ((bio = BIO_new(BIO_s_mem())) == NULL ||
	    BIO_write(bio, key_handle, key_handle_len) != (int)key_handle_len) {
		skdebug(__func__, "BIO setup failed");
		goto out;
	}
	if ((pk = PEM_read_bio_PrivateKey(bio, NULL, NULL, "")) == NULL) {
		skdebug(__func__, "PEM_read_bio_PrivateKey failed");
		goto out;
	}
	if (EVP_PKEY_base_id(pk) != EVP_PKEY_EC) {
		skdebug(__func__, "Not an EC key: %d", EVP_PKEY_base_id(pk));
		goto out;
	}
	if ((ec = EVP_PKEY_get1_EC_KEY(pk)) == NULL) {
		skdebug(__func__, "EVP_PKEY_get1_EC_KEY failed");
		goto out;
	}
	/* Expect message to be pre-hashed */
	if (message_len != SHA256_DIGEST_LENGTH) {
		skdebug(__func__, "bad message len %zu", message_len);
		goto out;
	}
	/* Prepare data to be signed */
	dump("message", message, message_len);
	SHA256Init(&ctx);
	SHA256Update(&ctx, application, strlen(application));
	SHA256Final(apphash, &ctx);
	dump("apphash", apphash, sizeof(apphash));
	countbuf[0] = (counter >> 24) & 0xff;
	countbuf[1] = (counter >> 16) & 0xff;
	countbuf[2] = (counter >> 8) & 0xff;
	countbuf[3] = counter & 0xff;
	dump("countbuf", countbuf, sizeof(countbuf));
	dump("flags", &flags, sizeof(flags));
	SHA256Init(&ctx);
	SHA256Update(&ctx, apphash, sizeof(apphash));
	SHA256Update(&ctx, &flags, sizeof(flags));
	SHA256Update(&ctx, countbuf, sizeof(countbuf));
	SHA256Update(&ctx, message, message_len);
	SHA256Final(sighash, &ctx);
	dump("sighash", sighash, sizeof(sighash));
	/* create and encode signature */
	if ((sig = ECDSA_do_sign(sighash, sizeof(sighash), ec)) == NULL) {
		skdebug(__func__, "ECDSA_do_sign failed");
		goto out;
	}
	ECDSA_SIG_get0(sig, &sig_r, &sig_s);
	response->sig_r_len = BN_num_bytes(sig_r);
	response->sig_s_len = BN_num_bytes(sig_s);
	if ((response->sig_r = calloc(1, response->sig_r_len)) == NULL ||
	    (response->sig_s = calloc(1, response->sig_s_len)) == NULL) {
		skdebug(__func__, "calloc signature failed");
		goto out;
	}
	BN_bn2bin(sig_r, response->sig_r);
	BN_bn2bin(sig_s, response->sig_s);
	ret = 0;
 out:
	explicit_bzero(&ctx, sizeof(ctx));
	explicit_bzero(&apphash, sizeof(apphash));
	explicit_bzero(&sighash, sizeof(sighash));
	ECDSA_SIG_free(sig);
	if (ret != 0) {
		free(response->sig_r);
		free(response->sig_s);
		response->sig_r = NULL;
		response->sig_s = NULL;
	}
	BIO_free(bio);
	EC_KEY_free(ec);
	EVP_PKEY_free(pk);
	return ret;
#else
	return -1;
#endif
}

static int
sig_ed25519(const uint8_t *message, size_t message_len,
    const char *application, uint32_t counter, uint8_t flags,
    const uint8_t *key_handle, size_t key_handle_len,
    struct sk_sign_response *response)
{
	size_t o;
	int ret = -1;
	SHA2_CTX ctx;
	uint8_t	apphash[SHA256_DIGEST_LENGTH];
	uint8_t signbuf[sizeof(apphash) + sizeof(flags) +
	    sizeof(counter) + SHA256_DIGEST_LENGTH];
	uint8_t sig[crypto_sign_ed25519_BYTES + sizeof(signbuf)];
	unsigned long long smlen;

	if (key_handle_len != crypto_sign_ed25519_SECRETKEYBYTES) {
		skdebug(__func__, "bad key handle length %zu", key_handle_len);
		goto out;
	}
	/* Expect message to be pre-hashed */
	if (message_len != SHA256_DIGEST_LENGTH) {
		skdebug(__func__, "bad message len %zu", message_len);
		goto out;
	}
	/* Prepare data to be signed */
	dump("message", message, message_len);
	SHA256Init(&ctx);
	SHA256Update(&ctx, application, strlen(application));
	SHA256Final(apphash, &ctx);
	dump("apphash", apphash, sizeof(apphash));

	memcpy(signbuf, apphash, sizeof(apphash));
	o = sizeof(apphash);
	signbuf[o++] = flags;
	signbuf[o++] = (counter >> 24) & 0xff;
	signbuf[o++] = (counter >> 16) & 0xff;
	signbuf[o++] = (counter >> 8) & 0xff;
	signbuf[o++] = counter & 0xff;
	memcpy(signbuf + o, message, message_len);
	o += message_len;
	if (o != sizeof(signbuf)) {
		skdebug(__func__, "bad sign buf len %zu, expected %zu",
		    o, sizeof(signbuf));
		goto out;
	}
	dump("signbuf", signbuf, sizeof(signbuf));
	/* create and encode signature */
	smlen = sizeof(signbuf);
	if (crypto_sign_ed25519(sig, &smlen, signbuf, sizeof(signbuf),
	    key_handle) != 0) {
		skdebug(__func__, "crypto_sign_ed25519 failed");
		goto out;
	}
	if (smlen <= sizeof(signbuf)) {
		skdebug(__func__, "bad sign smlen %llu, expected min %zu",
		    smlen, sizeof(signbuf) + 1);
		goto out;
	}
	response->sig_r_len = (size_t)(smlen - sizeof(signbuf));
	if ((response->sig_r = calloc(1, response->sig_r_len)) == NULL) {
		skdebug(__func__, "calloc signature failed");
		goto out;
	}
	memcpy(response->sig_r, sig, response->sig_r_len);
	dump("sig_r", response->sig_r, response->sig_r_len);
	ret = 0;
 out:
	explicit_bzero(&ctx, sizeof(ctx));
	explicit_bzero(&apphash, sizeof(apphash));
	explicit_bzero(&signbuf, sizeof(signbuf));
	explicit_bzero(&sig, sizeof(sig));
	if (ret != 0) {
		free(response->sig_r);
		response->sig_r = NULL;
	}
	return ret;
}

int
sk_sign(uint32_t alg, const uint8_t *data, size_t datalen,
    const char *application, const uint8_t *key_handle, size_t key_handle_len,
    uint8_t flags, const char *pin, struct sk_option **options,
    struct sk_sign_response **sign_response)
{
	struct sk_sign_response *response = NULL;
	int ret = SSH_SK_ERR_GENERAL;
	SHA2_CTX ctx;
	uint8_t message[32];

	if (sign_response == NULL) {
		skdebug(__func__, "sign_response == NULL");
		goto out;
	}
	*sign_response = NULL;
	if (check_options(options) != 0)
		goto out; /* error already logged */
	if ((response = calloc(1, sizeof(*response))) == NULL) {
		skdebug(__func__, "calloc response failed");
		goto out;
	}
	SHA256Init(&ctx);
	SHA256Update(&ctx, data, datalen);
	SHA256Final(message, &ctx);
	response->flags = flags;
	response->counter = 0x12345678;
	switch(alg) {
	case SSH_SK_ECDSA:
		if (sig_ecdsa(message, sizeof(message), application,
		    response->counter, flags, key_handle, key_handle_len,
		    response) != 0)
			goto out;
		break;
	case SSH_SK_ED25519:
		if (sig_ed25519(message, sizeof(message), application,
		    response->counter, flags, key_handle, key_handle_len,
		    response) != 0)
			goto out;
		break;
	default:
		skdebug(__func__, "unsupported key type %d", alg);
		return -1;
	}
	*sign_response = response;
	response = NULL;
	ret = 0;
 out:
	explicit_bzero(message, sizeof(message));
	if (response != NULL) {
		free(response->sig_r);
		free(response->sig_s);
		free(response);
	}
	return ret;
}

int
sk_load_resident_keys(const char *pin, struct sk_option **options,
    struct sk_resident_key ***rks, size_t *nrks)
{
	return SSH_SK_ERR_UNSUPPORTED;
}