1 /* $OpenBSD: ssh-sk.c,v 1.35 2021/02/26 00:16:58 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_f("calloc failed");
109 return NULL;
110 }
111 if ((ret->path = strdup(path)) == NULL) {
112 error_f("strdup failed");
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_f("provider %s implements version 0x%08lx", ret->path,
138 (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->authdata, r->authdata_len);
178 freezero(r, sizeof(*r));
179 }
180
181 static void
sshsk_free_sign_response(struct sk_sign_response * r)182 sshsk_free_sign_response(struct sk_sign_response *r)
183 {
184 if (r == NULL)
185 return;
186 freezero(r->sig_r, r->sig_r_len);
187 freezero(r->sig_s, r->sig_s_len);
188 freezero(r, sizeof(*r));
189 }
190
191 #ifdef WITH_OPENSSL
192 /* Assemble key from response */
193 static int
sshsk_ecdsa_assemble(struct sk_enroll_response * resp,struct sshkey ** keyp)194 sshsk_ecdsa_assemble(struct sk_enroll_response *resp, struct sshkey **keyp)
195 {
196 struct sshkey *key = NULL;
197 struct sshbuf *b = NULL;
198 EC_POINT *q = NULL;
199 int r;
200
201 *keyp = NULL;
202 if ((key = sshkey_new(KEY_ECDSA_SK)) == NULL) {
203 error_f("sshkey_new failed");
204 r = SSH_ERR_ALLOC_FAIL;
205 goto out;
206 }
207 key->ecdsa_nid = NID_X9_62_prime256v1;
208 if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL ||
209 (q = EC_POINT_new(EC_KEY_get0_group(key->ecdsa))) == NULL ||
210 (b = sshbuf_new()) == NULL) {
211 error_f("allocation failed");
212 r = SSH_ERR_ALLOC_FAIL;
213 goto out;
214 }
215 if ((r = sshbuf_put_string(b,
216 resp->public_key, resp->public_key_len)) != 0) {
217 error_fr(r, "sshbuf_put_string");
218 goto out;
219 }
220 if ((r = sshbuf_get_ec(b, q, EC_KEY_get0_group(key->ecdsa))) != 0) {
221 error_fr(r, "parse");
222 r = SSH_ERR_INVALID_FORMAT;
223 goto out;
224 }
225 if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa), q) != 0) {
226 error("Authenticator returned invalid ECDSA key");
227 r = SSH_ERR_KEY_INVALID_EC_VALUE;
228 goto out;
229 }
230 if (EC_KEY_set_public_key(key->ecdsa, q) != 1) {
231 /* XXX assume it is a allocation error */
232 error_f("allocation failed");
233 r = SSH_ERR_ALLOC_FAIL;
234 goto out;
235 }
236 /* success */
237 *keyp = key;
238 key = NULL; /* transferred */
239 r = 0;
240 out:
241 EC_POINT_free(q);
242 sshkey_free(key);
243 sshbuf_free(b);
244 return r;
245 }
246 #endif /* WITH_OPENSSL */
247
248 static int
sshsk_ed25519_assemble(struct sk_enroll_response * resp,struct sshkey ** keyp)249 sshsk_ed25519_assemble(struct sk_enroll_response *resp, struct sshkey **keyp)
250 {
251 struct sshkey *key = NULL;
252 int r;
253
254 *keyp = NULL;
255 if (resp->public_key_len != ED25519_PK_SZ) {
256 error_f("invalid size: %zu", resp->public_key_len);
257 r = SSH_ERR_INVALID_FORMAT;
258 goto out;
259 }
260 if ((key = sshkey_new(KEY_ED25519_SK)) == NULL) {
261 error_f("sshkey_new failed");
262 r = SSH_ERR_ALLOC_FAIL;
263 goto out;
264 }
265 if ((key->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) {
266 error_f("malloc failed");
267 r = SSH_ERR_ALLOC_FAIL;
268 goto out;
269 }
270 memcpy(key->ed25519_pk, resp->public_key, ED25519_PK_SZ);
271 /* success */
272 *keyp = key;
273 key = NULL; /* transferred */
274 r = 0;
275 out:
276 sshkey_free(key);
277 return r;
278 }
279
280 static int
sshsk_key_from_response(int alg,const char * application,uint8_t flags,struct sk_enroll_response * resp,struct sshkey ** keyp)281 sshsk_key_from_response(int alg, const char *application, uint8_t flags,
282 struct sk_enroll_response *resp, struct sshkey **keyp)
283 {
284 struct sshkey *key = NULL;
285 int r = SSH_ERR_INTERNAL_ERROR;
286
287 *keyp = NULL;
288
289 /* Check response validity */
290 if (resp->public_key == NULL || resp->key_handle == NULL) {
291 error_f("sk_enroll response invalid");
292 r = SSH_ERR_INVALID_FORMAT;
293 goto out;
294 }
295 switch (alg) {
296 #ifdef WITH_OPENSSL
297 case SSH_SK_ECDSA:
298 if ((r = sshsk_ecdsa_assemble(resp, &key)) != 0)
299 goto out;
300 break;
301 #endif /* WITH_OPENSSL */
302 case SSH_SK_ED25519:
303 if ((r = sshsk_ed25519_assemble(resp, &key)) != 0)
304 goto out;
305 break;
306 default:
307 error_f("unsupported algorithm %d", alg);
308 r = SSH_ERR_INVALID_ARGUMENT;
309 goto out;
310 }
311 key->sk_flags = flags;
312 if ((key->sk_key_handle = sshbuf_new()) == NULL ||
313 (key->sk_reserved = sshbuf_new()) == NULL) {
314 error_f("allocation failed");
315 r = SSH_ERR_ALLOC_FAIL;
316 goto out;
317 }
318 if ((key->sk_application = strdup(application)) == NULL) {
319 error_f("strdup application failed");
320 r = SSH_ERR_ALLOC_FAIL;
321 goto out;
322 }
323 if ((r = sshbuf_put(key->sk_key_handle, resp->key_handle,
324 resp->key_handle_len)) != 0) {
325 error_fr(r, "put key handle");
326 goto out;
327 }
328 /* success */
329 r = 0;
330 *keyp = key;
331 key = NULL;
332 out:
333 sshkey_free(key);
334 return r;
335 }
336
337 static int
skerr_to_ssherr(int skerr)338 skerr_to_ssherr(int skerr)
339 {
340 switch (skerr) {
341 case SSH_SK_ERR_UNSUPPORTED:
342 return SSH_ERR_FEATURE_UNSUPPORTED;
343 case SSH_SK_ERR_PIN_REQUIRED:
344 return SSH_ERR_KEY_WRONG_PASSPHRASE;
345 case SSH_SK_ERR_DEVICE_NOT_FOUND:
346 return SSH_ERR_DEVICE_NOT_FOUND;
347 case SSH_SK_ERR_GENERAL:
348 default:
349 return SSH_ERR_INVALID_FORMAT;
350 }
351 }
352
353 static void
sshsk_free_options(struct sk_option ** opts)354 sshsk_free_options(struct sk_option **opts)
355 {
356 size_t i;
357
358 if (opts == NULL)
359 return;
360 for (i = 0; opts[i] != NULL; i++) {
361 free(opts[i]->name);
362 free(opts[i]->value);
363 free(opts[i]);
364 }
365 free(opts);
366 }
367
368 static int
sshsk_add_option(struct sk_option *** optsp,size_t * noptsp,const char * name,const char * value,uint8_t required)369 sshsk_add_option(struct sk_option ***optsp, size_t *noptsp,
370 const char *name, const char *value, uint8_t required)
371 {
372 struct sk_option **opts = *optsp;
373 size_t nopts = *noptsp;
374
375 if ((opts = recallocarray(opts, nopts, nopts + 2, /* extra for NULL */
376 sizeof(*opts))) == NULL) {
377 error_f("array alloc failed");
378 return SSH_ERR_ALLOC_FAIL;
379 }
380 *optsp = opts;
381 *noptsp = nopts + 1;
382 if ((opts[nopts] = calloc(1, sizeof(**opts))) == NULL) {
383 error_f("alloc failed");
384 return SSH_ERR_ALLOC_FAIL;
385 }
386 if ((opts[nopts]->name = strdup(name)) == NULL ||
387 (opts[nopts]->value = strdup(value)) == NULL) {
388 error_f("alloc failed");
389 return SSH_ERR_ALLOC_FAIL;
390 }
391 opts[nopts]->required = required;
392 return 0;
393 }
394
395 static int
make_options(const char * device,const char * user_id,struct sk_option *** optsp)396 make_options(const char *device, const char *user_id,
397 struct sk_option ***optsp)
398 {
399 struct sk_option **opts = NULL;
400 size_t nopts = 0;
401 int r, ret = SSH_ERR_INTERNAL_ERROR;
402
403 if (device != NULL &&
404 (r = sshsk_add_option(&opts, &nopts, "device", device, 0)) != 0) {
405 ret = r;
406 goto out;
407 }
408 if (user_id != NULL &&
409 (r = sshsk_add_option(&opts, &nopts, "user", user_id, 0)) != 0) {
410 ret = r;
411 goto out;
412 }
413 /* success */
414 *optsp = opts;
415 opts = NULL;
416 nopts = 0;
417 ret = 0;
418 out:
419 sshsk_free_options(opts);
420 return ret;
421 }
422
423
424 static int
fill_attestation_blob(const struct sk_enroll_response * resp,struct sshbuf * attest)425 fill_attestation_blob(const struct sk_enroll_response *resp,
426 struct sshbuf *attest)
427 {
428 int r;
429
430 if (attest == NULL)
431 return 0; /* nothing to do */
432 if ((r = sshbuf_put_cstring(attest, "ssh-sk-attest-v01")) != 0 ||
433 (r = sshbuf_put_string(attest,
434 resp->attestation_cert, resp->attestation_cert_len)) != 0 ||
435 (r = sshbuf_put_string(attest,
436 resp->signature, resp->signature_len)) != 0 ||
437 (r = sshbuf_put_string(attest,
438 resp->authdata, resp->authdata_len)) != 0 ||
439 (r = sshbuf_put_u32(attest, 0)) != 0 || /* resvd flags */
440 (r = sshbuf_put_string(attest, NULL, 0)) != 0 /* resvd */) {
441 error_fr(r, "compose");
442 return r;
443 }
444 /* success */
445 return 0;
446 }
447
448 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)449 sshsk_enroll(int type, const char *provider_path, const char *device,
450 const char *application, const char *userid, uint8_t flags,
451 const char *pin, struct sshbuf *challenge_buf,
452 struct sshkey **keyp, struct sshbuf *attest)
453 {
454 struct sshsk_provider *skp = NULL;
455 struct sshkey *key = NULL;
456 u_char randchall[32];
457 const u_char *challenge;
458 size_t challenge_len;
459 struct sk_enroll_response *resp = NULL;
460 struct sk_option **opts = NULL;
461 int r = SSH_ERR_INTERNAL_ERROR;
462 int alg;
463
464 debug_f("provider \"%s\", device \"%s\", application \"%s\", "
465 "userid \"%s\", flags 0x%02x, challenge len %zu%s",
466 provider_path, device, application, userid, flags,
467 challenge_buf == NULL ? 0 : sshbuf_len(challenge_buf),
468 (pin != NULL && *pin != '\0') ? " with-pin" : "");
469
470 *keyp = NULL;
471 if (attest)
472 sshbuf_reset(attest);
473
474 if ((r = make_options(device, userid, &opts)) != 0)
475 goto out;
476
477 switch (type) {
478 #ifdef WITH_OPENSSL
479 case KEY_ECDSA_SK:
480 alg = SSH_SK_ECDSA;
481 break;
482 #endif /* WITH_OPENSSL */
483 case KEY_ED25519_SK:
484 alg = SSH_SK_ED25519;
485 break;
486 default:
487 error_f("unsupported key type");
488 r = SSH_ERR_INVALID_ARGUMENT;
489 goto out;
490 }
491 if (provider_path == NULL) {
492 error_f("missing provider");
493 r = SSH_ERR_INVALID_ARGUMENT;
494 goto out;
495 }
496 if (application == NULL || *application == '\0') {
497 error_f("missing application");
498 r = SSH_ERR_INVALID_ARGUMENT;
499 goto out;
500 }
501 if (challenge_buf == NULL) {
502 debug_f("using random challenge");
503 arc4random_buf(randchall, sizeof(randchall));
504 challenge = randchall;
505 challenge_len = sizeof(randchall);
506 } else if (sshbuf_len(challenge_buf) == 0) {
507 error("Missing enrollment challenge");
508 r = SSH_ERR_INVALID_ARGUMENT;
509 goto out;
510 } else {
511 challenge = sshbuf_ptr(challenge_buf);
512 challenge_len = sshbuf_len(challenge_buf);
513 debug3_f("using explicit challenge len=%zd", challenge_len);
514 }
515 if ((skp = sshsk_open(provider_path)) == NULL) {
516 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */
517 goto out;
518 }
519 /* XXX validate flags? */
520 /* enroll key */
521 if ((r = skp->sk_enroll(alg, challenge, challenge_len, application,
522 flags, pin, opts, &resp)) != 0) {
523 debug_f("provider \"%s\" failure %d", provider_path, r);
524 r = skerr_to_ssherr(r);
525 goto out;
526 }
527
528 if ((r = sshsk_key_from_response(alg, application, flags,
529 resp, &key)) != 0)
530 goto out;
531
532 /* Optionally fill in the attestation information */
533 if ((r = fill_attestation_blob(resp, attest)) != 0)
534 goto out;
535
536 /* success */
537 *keyp = key;
538 key = NULL; /* transferred */
539 r = 0;
540 out:
541 sshsk_free_options(opts);
542 sshsk_free(skp);
543 sshkey_free(key);
544 sshsk_free_enroll_response(resp);
545 explicit_bzero(randchall, sizeof(randchall));
546 return r;
547 }
548
549 #ifdef WITH_OPENSSL
550 static int
sshsk_ecdsa_sig(struct sk_sign_response * resp,struct sshbuf * sig)551 sshsk_ecdsa_sig(struct sk_sign_response *resp, struct sshbuf *sig)
552 {
553 struct sshbuf *inner_sig = NULL;
554 int r = SSH_ERR_INTERNAL_ERROR;
555
556 /* Check response validity */
557 if (resp->sig_r == NULL || resp->sig_s == NULL) {
558 error_f("sk_sign response invalid");
559 r = SSH_ERR_INVALID_FORMAT;
560 goto out;
561 }
562 if ((inner_sig = sshbuf_new()) == NULL) {
563 r = SSH_ERR_ALLOC_FAIL;
564 goto out;
565 }
566 /* Prepare and append inner signature object */
567 if ((r = sshbuf_put_bignum2_bytes(inner_sig,
568 resp->sig_r, resp->sig_r_len)) != 0 ||
569 (r = sshbuf_put_bignum2_bytes(inner_sig,
570 resp->sig_s, resp->sig_s_len)) != 0) {
571 error_fr(r, "compose inner");
572 goto out;
573 }
574 if ((r = sshbuf_put_stringb(sig, inner_sig)) != 0 ||
575 (r = sshbuf_put_u8(sig, resp->flags)) != 0 ||
576 (r = sshbuf_put_u32(sig, resp->counter)) != 0) {
577 error_fr(r, "compose");
578 goto out;
579 }
580 #ifdef DEBUG_SK
581 fprintf(stderr, "%s: sig_r:\n", __func__);
582 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr);
583 fprintf(stderr, "%s: sig_s:\n", __func__);
584 sshbuf_dump_data(resp->sig_s, resp->sig_s_len, stderr);
585 fprintf(stderr, "%s: inner:\n", __func__);
586 sshbuf_dump(inner_sig, stderr);
587 #endif
588 r = 0;
589 out:
590 sshbuf_free(inner_sig);
591 return r;
592 }
593 #endif /* WITH_OPENSSL */
594
595 static int
sshsk_ed25519_sig(struct sk_sign_response * resp,struct sshbuf * sig)596 sshsk_ed25519_sig(struct sk_sign_response *resp, struct sshbuf *sig)
597 {
598 int r = SSH_ERR_INTERNAL_ERROR;
599
600 /* Check response validity */
601 if (resp->sig_r == NULL) {
602 error_f("sk_sign response invalid");
603 r = SSH_ERR_INVALID_FORMAT;
604 goto out;
605 }
606 if ((r = sshbuf_put_string(sig,
607 resp->sig_r, resp->sig_r_len)) != 0 ||
608 (r = sshbuf_put_u8(sig, resp->flags)) != 0 ||
609 (r = sshbuf_put_u32(sig, resp->counter)) != 0) {
610 error_fr(r, "compose");
611 goto out;
612 }
613 #ifdef DEBUG_SK
614 fprintf(stderr, "%s: sig_r:\n", __func__);
615 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr);
616 #endif
617 r = 0;
618 out:
619 return r;
620 }
621
622 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)623 sshsk_sign(const char *provider_path, struct sshkey *key,
624 u_char **sigp, size_t *lenp, const u_char *data, size_t datalen,
625 u_int compat, const char *pin)
626 {
627 struct sshsk_provider *skp = NULL;
628 int r = SSH_ERR_INTERNAL_ERROR;
629 int type, alg;
630 struct sk_sign_response *resp = NULL;
631 struct sshbuf *inner_sig = NULL, *sig = NULL;
632 struct sk_option **opts = NULL;
633
634 debug_f("provider \"%s\", key %s, flags 0x%02x%s",
635 provider_path, sshkey_type(key), key->sk_flags,
636 (pin != NULL && *pin != '\0') ? " with-pin" : "");
637
638 if (sigp != NULL)
639 *sigp = NULL;
640 if (lenp != NULL)
641 *lenp = 0;
642 type = sshkey_type_plain(key->type);
643 switch (type) {
644 #ifdef WITH_OPENSSL
645 case KEY_ECDSA_SK:
646 alg = SSH_SK_ECDSA;
647 break;
648 #endif /* WITH_OPENSSL */
649 case KEY_ED25519_SK:
650 alg = SSH_SK_ED25519;
651 break;
652 default:
653 return SSH_ERR_INVALID_ARGUMENT;
654 }
655 if (provider_path == NULL ||
656 key->sk_key_handle == NULL ||
657 key->sk_application == NULL || *key->sk_application == '\0') {
658 r = SSH_ERR_INVALID_ARGUMENT;
659 goto out;
660 }
661 if ((skp = sshsk_open(provider_path)) == NULL) {
662 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */
663 goto out;
664 }
665 #ifdef DEBUG_SK
666 fprintf(stderr, "%s: sk_flags = 0x%02x, sk_application = \"%s\"\n",
667 __func__, key->sk_flags, key->sk_application);
668 fprintf(stderr, "%s: sk_key_handle:\n", __func__);
669 sshbuf_dump(key->sk_key_handle, stderr);
670 #endif
671 if ((r = skp->sk_sign(alg, data, datalen, key->sk_application,
672 sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle),
673 key->sk_flags, pin, opts, &resp)) != 0) {
674 debug_f("sk_sign failed with code %d", r);
675 r = skerr_to_ssherr(r);
676 goto out;
677 }
678 /* Assemble signature */
679 if ((sig = sshbuf_new()) == NULL) {
680 r = SSH_ERR_ALLOC_FAIL;
681 goto out;
682 }
683 if ((r = sshbuf_put_cstring(sig, sshkey_ssh_name_plain(key))) != 0) {
684 error_fr(r, "compose outer");
685 goto out;
686 }
687 switch (type) {
688 #ifdef WITH_OPENSSL
689 case KEY_ECDSA_SK:
690 if ((r = sshsk_ecdsa_sig(resp, sig)) != 0)
691 goto out;
692 break;
693 #endif /* WITH_OPENSSL */
694 case KEY_ED25519_SK:
695 if ((r = sshsk_ed25519_sig(resp, sig)) != 0)
696 goto out;
697 break;
698 }
699 #ifdef DEBUG_SK
700 fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n",
701 __func__, resp->flags, resp->counter);
702 fprintf(stderr, "%s: data to sign:\n", __func__);
703 sshbuf_dump_data(data, datalen, stderr);
704 fprintf(stderr, "%s: sigbuf:\n", __func__);
705 sshbuf_dump(sig, stderr);
706 #endif
707 if (sigp != NULL) {
708 if ((*sigp = malloc(sshbuf_len(sig))) == NULL) {
709 r = SSH_ERR_ALLOC_FAIL;
710 goto out;
711 }
712 memcpy(*sigp, sshbuf_ptr(sig), sshbuf_len(sig));
713 }
714 if (lenp != NULL)
715 *lenp = sshbuf_len(sig);
716 /* success */
717 r = 0;
718 out:
719 sshsk_free_options(opts);
720 sshsk_free(skp);
721 sshsk_free_sign_response(resp);
722 sshbuf_free(sig);
723 sshbuf_free(inner_sig);
724 return r;
725 }
726
727 static void
sshsk_free_sk_resident_keys(struct sk_resident_key ** rks,size_t nrks)728 sshsk_free_sk_resident_keys(struct sk_resident_key **rks, size_t nrks)
729 {
730 size_t i;
731
732 if (nrks == 0 || rks == NULL)
733 return;
734 for (i = 0; i < nrks; i++) {
735 free(rks[i]->application);
736 freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len);
737 freezero(rks[i]->key.public_key, rks[i]->key.public_key_len);
738 freezero(rks[i]->key.signature, rks[i]->key.signature_len);
739 freezero(rks[i]->key.attestation_cert,
740 rks[i]->key.attestation_cert_len);
741 freezero(rks[i], sizeof(**rks));
742 }
743 free(rks);
744 }
745
746 int
sshsk_load_resident(const char * provider_path,const char * device,const char * pin,struct sshkey *** keysp,size_t * nkeysp)747 sshsk_load_resident(const char *provider_path, const char *device,
748 const char *pin, struct sshkey ***keysp, size_t *nkeysp)
749 {
750 struct sshsk_provider *skp = NULL;
751 int r = SSH_ERR_INTERNAL_ERROR;
752 struct sk_resident_key **rks = NULL;
753 size_t i, nrks = 0, nkeys = 0;
754 struct sshkey *key = NULL, **keys = NULL, **tmp;
755 uint8_t flags;
756 struct sk_option **opts = NULL;
757
758 debug_f("provider \"%s\"%s", provider_path,
759 (pin != NULL && *pin != '\0') ? ", have-pin": "");
760
761 if (keysp == NULL || nkeysp == NULL)
762 return SSH_ERR_INVALID_ARGUMENT;
763 *keysp = NULL;
764 *nkeysp = 0;
765
766 if ((r = make_options(device, NULL, &opts)) != 0)
767 goto out;
768 if ((skp = sshsk_open(provider_path)) == NULL) {
769 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */
770 goto out;
771 }
772 if ((r = skp->sk_load_resident_keys(pin, opts, &rks, &nrks)) != 0) {
773 error("Provider \"%s\" returned failure %d", provider_path, r);
774 r = skerr_to_ssherr(r);
775 goto out;
776 }
777 for (i = 0; i < nrks; i++) {
778 debug3_f("rk %zu: slot = %zu, alg = %d, application = \"%s\"",
779 i, rks[i]->slot, rks[i]->alg, rks[i]->application);
780 /* XXX need better filter here */
781 if (strncmp(rks[i]->application, "ssh:", 4) != 0)
782 continue;
783 switch (rks[i]->alg) {
784 case SSH_SK_ECDSA:
785 case SSH_SK_ED25519:
786 break;
787 default:
788 continue;
789 }
790 flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY;
791 if ((rks[i]->flags & SSH_SK_USER_VERIFICATION_REQD))
792 flags |= SSH_SK_USER_VERIFICATION_REQD;
793 if ((r = sshsk_key_from_response(rks[i]->alg,
794 rks[i]->application, flags, &rks[i]->key, &key)) != 0)
795 goto out;
796 if ((tmp = recallocarray(keys, nkeys, nkeys + 1,
797 sizeof(*tmp))) == NULL) {
798 error_f("recallocarray failed");
799 r = SSH_ERR_ALLOC_FAIL;
800 goto out;
801 }
802 keys = tmp;
803 keys[nkeys++] = key;
804 key = NULL;
805 /* XXX synthesise comment */
806 }
807 /* success */
808 *keysp = keys;
809 *nkeysp = nkeys;
810 keys = NULL;
811 nkeys = 0;
812 r = 0;
813 out:
814 sshsk_free_options(opts);
815 sshsk_free(skp);
816 sshsk_free_sk_resident_keys(rks, nrks);
817 sshkey_free(key);
818 if (nkeys != 0) {
819 for (i = 0; i < nkeys; i++)
820 sshkey_free(keys[i]);
821 free(keys);
822 }
823 return r;
824 }
825
826 #endif /* ENABLE_SK */
827