1 /* $OpenBSD: ssh-sk.c,v 1.30 2020/04/28 04:02:29 djm Exp $ */
2 /*
3 * Copyright (c) 2019 Google LLC
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 /* #define DEBUG_SK 1 */
19
20 #include "includes.h"
21
22 #ifdef ENABLE_SK
23
24 #include <dlfcn.h>
25 #include <stddef.h>
26 #ifdef HAVE_STDINT_H
27 # include <stdint.h>
28 #endif
29 #include <string.h>
30 #include <stdio.h>
31
32 #ifdef WITH_OPENSSL
33 #include <openssl/objects.h>
34 #include <openssl/ec.h>
35 #endif /* WITH_OPENSSL */
36
37 #include "log.h"
38 #include "misc.h"
39 #include "sshbuf.h"
40 #include "sshkey.h"
41 #include "ssherr.h"
42 #include "digest.h"
43
44 #include "ssh-sk.h"
45 #include "sk-api.h"
46 #include "crypto_api.h"
47
48 struct sshsk_provider {
49 char *path;
50 void *dlhandle;
51
52 /* Return the version of the middleware API */
53 uint32_t (*sk_api_version)(void);
54
55 /* Enroll a U2F key (private key generation) */
56 int (*sk_enroll)(int alg, const uint8_t *challenge,
57 size_t challenge_len, const char *application, uint8_t flags,
58 const char *pin, struct sk_option **opts,
59 struct sk_enroll_response **enroll_response);
60
61 /* Sign a challenge */
62 int (*sk_sign)(int alg, const uint8_t *message, size_t message_len,
63 const char *application,
64 const uint8_t *key_handle, size_t key_handle_len,
65 uint8_t flags, const char *pin, struct sk_option **opts,
66 struct sk_sign_response **sign_response);
67
68 /* Enumerate resident keys */
69 int (*sk_load_resident_keys)(const char *pin, struct sk_option **opts,
70 struct sk_resident_key ***rks, size_t *nrks);
71 };
72
73 /* Built-in version */
74 int ssh_sk_enroll(int alg, const uint8_t *challenge,
75 size_t challenge_len, const char *application, uint8_t flags,
76 const char *pin, struct sk_option **opts,
77 struct sk_enroll_response **enroll_response);
78 int ssh_sk_sign(int alg, const uint8_t *message, size_t message_len,
79 const char *application,
80 const uint8_t *key_handle, size_t key_handle_len,
81 uint8_t flags, const char *pin, struct sk_option **opts,
82 struct sk_sign_response **sign_response);
83 int ssh_sk_load_resident_keys(const char *pin, struct sk_option **opts,
84 struct sk_resident_key ***rks, size_t *nrks);
85
86 static void
sshsk_free(struct sshsk_provider * p)87 sshsk_free(struct sshsk_provider *p)
88 {
89 if (p == NULL)
90 return;
91 free(p->path);
92 if (p->dlhandle != NULL)
93 dlclose(p->dlhandle);
94 free(p);
95 }
96
97 static struct sshsk_provider *
sshsk_open(const char * path)98 sshsk_open(const char *path)
99 {
100 struct sshsk_provider *ret = NULL;
101 uint32_t version;
102
103 if (path == NULL || *path == '\0') {
104 error("No FIDO SecurityKeyProvider specified");
105 return NULL;
106 }
107 if ((ret = calloc(1, sizeof(*ret))) == NULL) {
108 error("%s: calloc failed", __func__);
109 return NULL;
110 }
111 if ((ret->path = strdup(path)) == NULL) {
112 error("%s: strdup failed", __func__);
113 goto fail;
114 }
115 /* Skip the rest if we're using the linked in middleware */
116 if (strcasecmp(ret->path, "internal") == 0) {
117 #ifdef ENABLE_SK_INTERNAL
118 ret->sk_enroll = ssh_sk_enroll;
119 ret->sk_sign = ssh_sk_sign;
120 ret->sk_load_resident_keys = ssh_sk_load_resident_keys;
121 #else
122 error("internal security key support not enabled");
123 #endif
124 return ret;
125 }
126 if ((ret->dlhandle = dlopen(path, RTLD_NOW)) == NULL) {
127 error("Provider \"%s\" dlopen failed: %s", path, dlerror());
128 goto fail;
129 }
130 if ((ret->sk_api_version = dlsym(ret->dlhandle,
131 "sk_api_version")) == NULL) {
132 error("Provider \"%s\" dlsym(sk_api_version) failed: %s",
133 path, dlerror());
134 goto fail;
135 }
136 version = ret->sk_api_version();
137 debug("%s: provider %s implements version 0x%08lx", __func__,
138 ret->path, (u_long)version);
139 if ((version & SSH_SK_VERSION_MAJOR_MASK) != SSH_SK_VERSION_MAJOR) {
140 error("Provider \"%s\" implements unsupported "
141 "version 0x%08lx (supported: 0x%08lx)",
142 path, (u_long)version, (u_long)SSH_SK_VERSION_MAJOR);
143 goto fail;
144 }
145 if ((ret->sk_enroll = dlsym(ret->dlhandle, "sk_enroll")) == NULL) {
146 error("Provider %s dlsym(sk_enroll) failed: %s",
147 path, dlerror());
148 goto fail;
149 }
150 if ((ret->sk_sign = dlsym(ret->dlhandle, "sk_sign")) == NULL) {
151 error("Provider \"%s\" dlsym(sk_sign) failed: %s",
152 path, dlerror());
153 goto fail;
154 }
155 if ((ret->sk_load_resident_keys = dlsym(ret->dlhandle,
156 "sk_load_resident_keys")) == NULL) {
157 error("Provider \"%s\" dlsym(sk_load_resident_keys) "
158 "failed: %s", path, dlerror());
159 goto fail;
160 }
161 /* success */
162 return ret;
163 fail:
164 sshsk_free(ret);
165 return NULL;
166 }
167
168 static void
sshsk_free_enroll_response(struct sk_enroll_response * r)169 sshsk_free_enroll_response(struct sk_enroll_response *r)
170 {
171 if (r == NULL)
172 return;
173 freezero(r->key_handle, r->key_handle_len);
174 freezero(r->public_key, r->public_key_len);
175 freezero(r->signature, r->signature_len);
176 freezero(r->attestation_cert, r->attestation_cert_len);
177 freezero(r, sizeof(*r));
178 }
179
180 static void
sshsk_free_sign_response(struct sk_sign_response * r)181 sshsk_free_sign_response(struct sk_sign_response *r)
182 {
183 if (r == NULL)
184 return;
185 freezero(r->sig_r, r->sig_r_len);
186 freezero(r->sig_s, r->sig_s_len);
187 freezero(r, sizeof(*r));
188 }
189
190 #ifdef WITH_OPENSSL
191 /* Assemble key from response */
192 static int
sshsk_ecdsa_assemble(struct sk_enroll_response * resp,struct sshkey ** keyp)193 sshsk_ecdsa_assemble(struct sk_enroll_response *resp, struct sshkey **keyp)
194 {
195 struct sshkey *key = NULL;
196 struct sshbuf *b = NULL;
197 EC_POINT *q = NULL;
198 int r;
199
200 *keyp = NULL;
201 if ((key = sshkey_new(KEY_ECDSA_SK)) == NULL) {
202 error("%s: sshkey_new failed", __func__);
203 r = SSH_ERR_ALLOC_FAIL;
204 goto out;
205 }
206 key->ecdsa_nid = NID_X9_62_prime256v1;
207 if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL ||
208 (q = EC_POINT_new(EC_KEY_get0_group(key->ecdsa))) == NULL ||
209 (b = sshbuf_new()) == NULL) {
210 error("%s: allocation failed", __func__);
211 r = SSH_ERR_ALLOC_FAIL;
212 goto out;
213 }
214 if ((r = sshbuf_put_string(b,
215 resp->public_key, resp->public_key_len)) != 0) {
216 error("%s: buffer error: %s", __func__, ssh_err(r));
217 goto out;
218 }
219 if ((r = sshbuf_get_ec(b, q, EC_KEY_get0_group(key->ecdsa))) != 0) {
220 error("%s: parse key: %s", __func__, ssh_err(r));
221 r = SSH_ERR_INVALID_FORMAT;
222 goto out;
223 }
224 if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa), q) != 0) {
225 error("Authenticator returned invalid ECDSA key");
226 r = SSH_ERR_KEY_INVALID_EC_VALUE;
227 goto out;
228 }
229 if (EC_KEY_set_public_key(key->ecdsa, q) != 1) {
230 /* XXX assume it is a allocation error */
231 error("%s: allocation failed", __func__);
232 r = SSH_ERR_ALLOC_FAIL;
233 goto out;
234 }
235 /* success */
236 *keyp = key;
237 key = NULL; /* transferred */
238 r = 0;
239 out:
240 EC_POINT_free(q);
241 sshkey_free(key);
242 sshbuf_free(b);
243 return r;
244 }
245 #endif /* WITH_OPENSSL */
246
247 static int
sshsk_ed25519_assemble(struct sk_enroll_response * resp,struct sshkey ** keyp)248 sshsk_ed25519_assemble(struct sk_enroll_response *resp, struct sshkey **keyp)
249 {
250 struct sshkey *key = NULL;
251 int r;
252
253 *keyp = NULL;
254 if (resp->public_key_len != ED25519_PK_SZ) {
255 error("%s: invalid size: %zu", __func__, resp->public_key_len);
256 r = SSH_ERR_INVALID_FORMAT;
257 goto out;
258 }
259 if ((key = sshkey_new(KEY_ED25519_SK)) == NULL) {
260 error("%s: sshkey_new failed", __func__);
261 r = SSH_ERR_ALLOC_FAIL;
262 goto out;
263 }
264 if ((key->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) {
265 error("%s: malloc failed", __func__);
266 r = SSH_ERR_ALLOC_FAIL;
267 goto out;
268 }
269 memcpy(key->ed25519_pk, resp->public_key, ED25519_PK_SZ);
270 /* success */
271 *keyp = key;
272 key = NULL; /* transferred */
273 r = 0;
274 out:
275 sshkey_free(key);
276 return r;
277 }
278
279 static int
sshsk_key_from_response(int alg,const char * application,uint8_t flags,struct sk_enroll_response * resp,struct sshkey ** keyp)280 sshsk_key_from_response(int alg, const char *application, uint8_t flags,
281 struct sk_enroll_response *resp, struct sshkey **keyp)
282 {
283 struct sshkey *key = NULL;
284 int r = SSH_ERR_INTERNAL_ERROR;
285
286 *keyp = NULL;
287
288 /* Check response validity */
289 if (resp->public_key == NULL || resp->key_handle == NULL) {
290 error("%s: sk_enroll response invalid", __func__);
291 r = SSH_ERR_INVALID_FORMAT;
292 goto out;
293 }
294 switch (alg) {
295 #ifdef WITH_OPENSSL
296 case SSH_SK_ECDSA:
297 if ((r = sshsk_ecdsa_assemble(resp, &key)) != 0)
298 goto out;
299 break;
300 #endif /* WITH_OPENSSL */
301 case SSH_SK_ED25519:
302 if ((r = sshsk_ed25519_assemble(resp, &key)) != 0)
303 goto out;
304 break;
305 default:
306 error("%s: unsupported algorithm %d", __func__, alg);
307 r = SSH_ERR_INVALID_ARGUMENT;
308 goto out;
309 }
310 key->sk_flags = flags;
311 if ((key->sk_key_handle = sshbuf_new()) == NULL ||
312 (key->sk_reserved = sshbuf_new()) == NULL) {
313 error("%s: allocation failed", __func__);
314 r = SSH_ERR_ALLOC_FAIL;
315 goto out;
316 }
317 if ((key->sk_application = strdup(application)) == NULL) {
318 error("%s: strdup application failed", __func__);
319 r = SSH_ERR_ALLOC_FAIL;
320 goto out;
321 }
322 if ((r = sshbuf_put(key->sk_key_handle, resp->key_handle,
323 resp->key_handle_len)) != 0) {
324 error("%s: buffer error: %s", __func__, ssh_err(r));
325 goto out;
326 }
327 /* success */
328 r = 0;
329 *keyp = key;
330 key = NULL;
331 out:
332 sshkey_free(key);
333 return r;
334 }
335
336 static int
skerr_to_ssherr(int skerr)337 skerr_to_ssherr(int skerr)
338 {
339 switch (skerr) {
340 case SSH_SK_ERR_UNSUPPORTED:
341 return SSH_ERR_FEATURE_UNSUPPORTED;
342 case SSH_SK_ERR_PIN_REQUIRED:
343 return SSH_ERR_KEY_WRONG_PASSPHRASE;
344 case SSH_SK_ERR_DEVICE_NOT_FOUND:
345 return SSH_ERR_DEVICE_NOT_FOUND;
346 case SSH_SK_ERR_GENERAL:
347 default:
348 return SSH_ERR_INVALID_FORMAT;
349 }
350 }
351
352 static void
sshsk_free_options(struct sk_option ** opts)353 sshsk_free_options(struct sk_option **opts)
354 {
355 size_t i;
356
357 if (opts == NULL)
358 return;
359 for (i = 0; opts[i] != NULL; i++) {
360 free(opts[i]->name);
361 free(opts[i]->value);
362 free(opts[i]);
363 }
364 free(opts);
365 }
366
367 static int
sshsk_add_option(struct sk_option *** optsp,size_t * noptsp,const char * name,const char * value,uint8_t required)368 sshsk_add_option(struct sk_option ***optsp, size_t *noptsp,
369 const char *name, const char *value, uint8_t required)
370 {
371 struct sk_option **opts = *optsp;
372 size_t nopts = *noptsp;
373
374 if ((opts = recallocarray(opts, nopts, nopts + 2, /* extra for NULL */
375 sizeof(*opts))) == NULL) {
376 error("%s: array alloc failed", __func__);
377 return SSH_ERR_ALLOC_FAIL;
378 }
379 *optsp = opts;
380 *noptsp = nopts + 1;
381 if ((opts[nopts] = calloc(1, sizeof(**opts))) == NULL) {
382 error("%s: alloc failed", __func__);
383 return SSH_ERR_ALLOC_FAIL;
384 }
385 if ((opts[nopts]->name = strdup(name)) == NULL ||
386 (opts[nopts]->value = strdup(value)) == NULL) {
387 error("%s: alloc failed", __func__);
388 return SSH_ERR_ALLOC_FAIL;
389 }
390 opts[nopts]->required = required;
391 return 0;
392 }
393
394 static int
make_options(const char * device,const char * user_id,struct sk_option *** optsp)395 make_options(const char *device, const char *user_id,
396 struct sk_option ***optsp)
397 {
398 struct sk_option **opts = NULL;
399 size_t nopts = 0;
400 int r, ret = SSH_ERR_INTERNAL_ERROR;
401
402 if (device != NULL &&
403 (r = sshsk_add_option(&opts, &nopts, "device", device, 0)) != 0) {
404 ret = r;
405 goto out;
406 }
407 if (user_id != NULL &&
408 (r = sshsk_add_option(&opts, &nopts, "user", user_id, 0)) != 0) {
409 ret = r;
410 goto out;
411 }
412 /* success */
413 *optsp = opts;
414 opts = NULL;
415 nopts = 0;
416 ret = 0;
417 out:
418 sshsk_free_options(opts);
419 return ret;
420 }
421
422 int
sshsk_enroll(int type,const char * provider_path,const char * device,const char * application,const char * userid,uint8_t flags,const char * pin,struct sshbuf * challenge_buf,struct sshkey ** keyp,struct sshbuf * attest)423 sshsk_enroll(int type, const char *provider_path, const char *device,
424 const char *application, const char *userid, uint8_t flags,
425 const char *pin, struct sshbuf *challenge_buf,
426 struct sshkey **keyp, struct sshbuf *attest)
427 {
428 struct sshsk_provider *skp = NULL;
429 struct sshkey *key = NULL;
430 u_char randchall[32];
431 const u_char *challenge;
432 size_t challenge_len;
433 struct sk_enroll_response *resp = NULL;
434 struct sk_option **opts = NULL;
435 int r = SSH_ERR_INTERNAL_ERROR;
436 int alg;
437
438 debug("%s: provider \"%s\", device \"%s\", application \"%s\", "
439 "userid \"%s\", flags 0x%02x, challenge len %zu%s", __func__,
440 provider_path, device, application, userid, flags,
441 challenge_buf == NULL ? 0 : sshbuf_len(challenge_buf),
442 (pin != NULL && *pin != '\0') ? " with-pin" : "");
443
444 *keyp = NULL;
445 if (attest)
446 sshbuf_reset(attest);
447
448 if ((r = make_options(device, userid, &opts)) != 0)
449 goto out;
450
451 switch (type) {
452 #ifdef WITH_OPENSSL
453 case KEY_ECDSA_SK:
454 alg = SSH_SK_ECDSA;
455 break;
456 #endif /* WITH_OPENSSL */
457 case KEY_ED25519_SK:
458 alg = SSH_SK_ED25519;
459 break;
460 default:
461 error("%s: unsupported key type", __func__);
462 r = SSH_ERR_INVALID_ARGUMENT;
463 goto out;
464 }
465 if (provider_path == NULL) {
466 error("%s: missing provider", __func__);
467 r = SSH_ERR_INVALID_ARGUMENT;
468 goto out;
469 }
470 if (application == NULL || *application == '\0') {
471 error("%s: missing application", __func__);
472 r = SSH_ERR_INVALID_ARGUMENT;
473 goto out;
474 }
475 if (challenge_buf == NULL) {
476 debug("%s: using random challenge", __func__);
477 arc4random_buf(randchall, sizeof(randchall));
478 challenge = randchall;
479 challenge_len = sizeof(randchall);
480 } else if (sshbuf_len(challenge_buf) == 0) {
481 error("Missing enrollment challenge");
482 r = SSH_ERR_INVALID_ARGUMENT;
483 goto out;
484 } else {
485 challenge = sshbuf_ptr(challenge_buf);
486 challenge_len = sshbuf_len(challenge_buf);
487 debug3("%s: using explicit challenge len=%zd",
488 __func__, challenge_len);
489 }
490 if ((skp = sshsk_open(provider_path)) == NULL) {
491 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */
492 goto out;
493 }
494 /* XXX validate flags? */
495 /* enroll key */
496 if ((r = skp->sk_enroll(alg, challenge, challenge_len, application,
497 flags, pin, opts, &resp)) != 0) {
498 debug("%s: provider \"%s\" returned failure %d", __func__,
499 provider_path, r);
500 r = skerr_to_ssherr(r);
501 goto out;
502 }
503
504 if ((r = sshsk_key_from_response(alg, application, flags,
505 resp, &key)) != 0)
506 goto out;
507
508 /* Optionally fill in the attestation information */
509 if (attest != NULL) {
510 if ((r = sshbuf_put_cstring(attest,
511 "ssh-sk-attest-v00")) != 0 ||
512 (r = sshbuf_put_string(attest,
513 resp->attestation_cert, resp->attestation_cert_len)) != 0 ||
514 (r = sshbuf_put_string(attest,
515 resp->signature, resp->signature_len)) != 0 ||
516 (r = sshbuf_put_u32(attest, 0)) != 0 || /* resvd flags */
517 (r = sshbuf_put_string(attest, NULL, 0)) != 0 /* resvd */) {
518 error("%s: buffer error: %s", __func__, ssh_err(r));
519 goto out;
520 }
521 }
522 /* success */
523 *keyp = key;
524 key = NULL; /* transferred */
525 r = 0;
526 out:
527 sshsk_free_options(opts);
528 sshsk_free(skp);
529 sshkey_free(key);
530 sshsk_free_enroll_response(resp);
531 explicit_bzero(randchall, sizeof(randchall));
532 return r;
533 }
534
535 #ifdef WITH_OPENSSL
536 static int
sshsk_ecdsa_sig(struct sk_sign_response * resp,struct sshbuf * sig)537 sshsk_ecdsa_sig(struct sk_sign_response *resp, struct sshbuf *sig)
538 {
539 struct sshbuf *inner_sig = NULL;
540 int r = SSH_ERR_INTERNAL_ERROR;
541
542 /* Check response validity */
543 if (resp->sig_r == NULL || resp->sig_s == NULL) {
544 error("%s: sk_sign response invalid", __func__);
545 r = SSH_ERR_INVALID_FORMAT;
546 goto out;
547 }
548 if ((inner_sig = sshbuf_new()) == NULL) {
549 r = SSH_ERR_ALLOC_FAIL;
550 goto out;
551 }
552 /* Prepare and append inner signature object */
553 if ((r = sshbuf_put_bignum2_bytes(inner_sig,
554 resp->sig_r, resp->sig_r_len)) != 0 ||
555 (r = sshbuf_put_bignum2_bytes(inner_sig,
556 resp->sig_s, resp->sig_s_len)) != 0) {
557 debug("%s: buffer error: %s", __func__, ssh_err(r));
558 goto out;
559 }
560 if ((r = sshbuf_put_stringb(sig, inner_sig)) != 0 ||
561 (r = sshbuf_put_u8(sig, resp->flags)) != 0 ||
562 (r = sshbuf_put_u32(sig, resp->counter)) != 0) {
563 debug("%s: buffer error: %s", __func__, ssh_err(r));
564 goto out;
565 }
566 #ifdef DEBUG_SK
567 fprintf(stderr, "%s: sig_r:\n", __func__);
568 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr);
569 fprintf(stderr, "%s: sig_s:\n", __func__);
570 sshbuf_dump_data(resp->sig_s, resp->sig_s_len, stderr);
571 fprintf(stderr, "%s: inner:\n", __func__);
572 sshbuf_dump(inner_sig, stderr);
573 #endif
574 r = 0;
575 out:
576 sshbuf_free(inner_sig);
577 return r;
578 }
579 #endif /* WITH_OPENSSL */
580
581 static int
sshsk_ed25519_sig(struct sk_sign_response * resp,struct sshbuf * sig)582 sshsk_ed25519_sig(struct sk_sign_response *resp, struct sshbuf *sig)
583 {
584 int r = SSH_ERR_INTERNAL_ERROR;
585
586 /* Check response validity */
587 if (resp->sig_r == NULL) {
588 error("%s: sk_sign response invalid", __func__);
589 r = SSH_ERR_INVALID_FORMAT;
590 goto out;
591 }
592 if ((r = sshbuf_put_string(sig,
593 resp->sig_r, resp->sig_r_len)) != 0 ||
594 (r = sshbuf_put_u8(sig, resp->flags)) != 0 ||
595 (r = sshbuf_put_u32(sig, resp->counter)) != 0) {
596 debug("%s: buffer error: %s", __func__, ssh_err(r));
597 goto out;
598 }
599 #ifdef DEBUG_SK
600 fprintf(stderr, "%s: sig_r:\n", __func__);
601 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr);
602 #endif
603 r = 0;
604 out:
605 return r;
606 }
607
608 int
sshsk_sign(const char * provider_path,struct sshkey * key,u_char ** sigp,size_t * lenp,const u_char * data,size_t datalen,u_int compat,const char * pin)609 sshsk_sign(const char *provider_path, struct sshkey *key,
610 u_char **sigp, size_t *lenp, const u_char *data, size_t datalen,
611 u_int compat, const char *pin)
612 {
613 struct sshsk_provider *skp = NULL;
614 int r = SSH_ERR_INTERNAL_ERROR;
615 int type, alg;
616 struct sk_sign_response *resp = NULL;
617 struct sshbuf *inner_sig = NULL, *sig = NULL;
618 struct sk_option **opts = NULL;
619
620 debug("%s: provider \"%s\", key %s, flags 0x%02x%s", __func__,
621 provider_path, sshkey_type(key), key->sk_flags,
622 (pin != NULL && *pin != '\0') ? " with-pin" : "");
623
624 if (sigp != NULL)
625 *sigp = NULL;
626 if (lenp != NULL)
627 *lenp = 0;
628 type = sshkey_type_plain(key->type);
629 switch (type) {
630 #ifdef WITH_OPENSSL
631 case KEY_ECDSA_SK:
632 alg = SSH_SK_ECDSA;
633 break;
634 #endif /* WITH_OPENSSL */
635 case KEY_ED25519_SK:
636 alg = SSH_SK_ED25519;
637 break;
638 default:
639 return SSH_ERR_INVALID_ARGUMENT;
640 }
641 if (provider_path == NULL ||
642 key->sk_key_handle == NULL ||
643 key->sk_application == NULL || *key->sk_application == '\0') {
644 r = SSH_ERR_INVALID_ARGUMENT;
645 goto out;
646 }
647 if ((skp = sshsk_open(provider_path)) == NULL) {
648 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */
649 goto out;
650 }
651
652 if ((r = skp->sk_sign(alg, data, datalen, key->sk_application,
653 sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle),
654 key->sk_flags, pin, opts, &resp)) != 0) {
655 debug("%s: sk_sign failed with code %d", __func__, r);
656 r = skerr_to_ssherr(r);
657 goto out;
658 }
659 /* Assemble signature */
660 if ((sig = sshbuf_new()) == NULL) {
661 r = SSH_ERR_ALLOC_FAIL;
662 goto out;
663 }
664 if ((r = sshbuf_put_cstring(sig, sshkey_ssh_name_plain(key))) != 0) {
665 debug("%s: buffer error (outer): %s", __func__, ssh_err(r));
666 goto out;
667 }
668 switch (type) {
669 #ifdef WITH_OPENSSL
670 case KEY_ECDSA_SK:
671 if ((r = sshsk_ecdsa_sig(resp, sig)) != 0)
672 goto out;
673 break;
674 #endif /* WITH_OPENSSL */
675 case KEY_ED25519_SK:
676 if ((r = sshsk_ed25519_sig(resp, sig)) != 0)
677 goto out;
678 break;
679 }
680 #ifdef DEBUG_SK
681 fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n",
682 __func__, resp->flags, resp->counter);
683 fprintf(stderr, "%s: hashed message:\n", __func__);
684 sshbuf_dump_data(message, sizeof(message), stderr);
685 fprintf(stderr, "%s: sigbuf:\n", __func__);
686 sshbuf_dump(sig, stderr);
687 #endif
688 if (sigp != NULL) {
689 if ((*sigp = malloc(sshbuf_len(sig))) == NULL) {
690 r = SSH_ERR_ALLOC_FAIL;
691 goto out;
692 }
693 memcpy(*sigp, sshbuf_ptr(sig), sshbuf_len(sig));
694 }
695 if (lenp != NULL)
696 *lenp = sshbuf_len(sig);
697 /* success */
698 r = 0;
699 out:
700 sshsk_free_options(opts);
701 sshsk_free(skp);
702 sshsk_free_sign_response(resp);
703 sshbuf_free(sig);
704 sshbuf_free(inner_sig);
705 return r;
706 }
707
708 static void
sshsk_free_sk_resident_keys(struct sk_resident_key ** rks,size_t nrks)709 sshsk_free_sk_resident_keys(struct sk_resident_key **rks, size_t nrks)
710 {
711 size_t i;
712
713 if (nrks == 0 || rks == NULL)
714 return;
715 for (i = 0; i < nrks; i++) {
716 free(rks[i]->application);
717 freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len);
718 freezero(rks[i]->key.public_key, rks[i]->key.public_key_len);
719 freezero(rks[i]->key.signature, rks[i]->key.signature_len);
720 freezero(rks[i]->key.attestation_cert,
721 rks[i]->key.attestation_cert_len);
722 freezero(rks[i], sizeof(**rks));
723 }
724 free(rks);
725 }
726
727 int
sshsk_load_resident(const char * provider_path,const char * device,const char * pin,struct sshkey *** keysp,size_t * nkeysp)728 sshsk_load_resident(const char *provider_path, const char *device,
729 const char *pin, struct sshkey ***keysp, size_t *nkeysp)
730 {
731 struct sshsk_provider *skp = NULL;
732 int r = SSH_ERR_INTERNAL_ERROR;
733 struct sk_resident_key **rks = NULL;
734 size_t i, nrks = 0, nkeys = 0;
735 struct sshkey *key = NULL, **keys = NULL, **tmp;
736 uint8_t flags;
737 struct sk_option **opts = NULL;
738
739 debug("%s: provider \"%s\"%s", __func__, provider_path,
740 (pin != NULL && *pin != '\0') ? ", have-pin": "");
741
742 if (keysp == NULL || nkeysp == NULL)
743 return SSH_ERR_INVALID_ARGUMENT;
744 *keysp = NULL;
745 *nkeysp = 0;
746
747 if ((r = make_options(device, NULL, &opts)) != 0)
748 goto out;
749 if ((skp = sshsk_open(provider_path)) == NULL) {
750 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */
751 goto out;
752 }
753 if ((r = skp->sk_load_resident_keys(pin, opts, &rks, &nrks)) != 0) {
754 error("Provider \"%s\" returned failure %d", provider_path, r);
755 r = skerr_to_ssherr(r);
756 goto out;
757 }
758 for (i = 0; i < nrks; i++) {
759 debug3("%s: rk %zu: slot = %zu, alg = %d, application = \"%s\"",
760 __func__, i, rks[i]->slot, rks[i]->alg,
761 rks[i]->application);
762 /* XXX need better filter here */
763 if (strncmp(rks[i]->application, "ssh:", 4) != 0)
764 continue;
765 switch (rks[i]->alg) {
766 case SSH_SK_ECDSA:
767 case SSH_SK_ED25519:
768 break;
769 default:
770 continue;
771 }
772 /* XXX where to get flags? */
773 flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY;
774 if ((r = sshsk_key_from_response(rks[i]->alg,
775 rks[i]->application, flags, &rks[i]->key, &key)) != 0)
776 goto out;
777 if ((tmp = recallocarray(keys, nkeys, nkeys + 1,
778 sizeof(*tmp))) == NULL) {
779 error("%s: recallocarray failed", __func__);
780 r = SSH_ERR_ALLOC_FAIL;
781 goto out;
782 }
783 keys = tmp;
784 keys[nkeys++] = key;
785 key = NULL;
786 /* XXX synthesise comment */
787 }
788 /* success */
789 *keysp = keys;
790 *nkeysp = nkeys;
791 keys = NULL;
792 nkeys = 0;
793 r = 0;
794 out:
795 sshsk_free_options(opts);
796 sshsk_free(skp);
797 sshsk_free_sk_resident_keys(rks, nrks);
798 sshkey_free(key);
799 if (nkeys != 0) {
800 for (i = 0; i < nkeys; i++)
801 sshkey_free(keys[i]);
802 free(keys);
803 }
804 return r;
805 }
806
807 #endif /* ENABLE_SK */
808