summaryrefslogtreecommitdiff
path: root/ssh-sk.c
diff options
context:
space:
mode:
Diffstat (limited to 'ssh-sk.c')
-rw-r--r--ssh-sk.c813
1 files changed, 813 insertions, 0 deletions
diff --git a/ssh-sk.c b/ssh-sk.c
new file mode 100644
index 000000000..5ff938193
--- /dev/null
+++ b/ssh-sk.c
@@ -0,0 +1,813 @@
1/* $OpenBSD: ssh-sk.c,v 1.27 2020/02/06 22:30:54 naddy 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
48struct 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 */
74int 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);
78int 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);
83int ssh_sk_load_resident_keys(const char *pin, struct sk_option **opts,
84 struct sk_resident_key ***rks, size_t *nrks);
85
86static void
87sshsk_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
97static struct sshsk_provider *
98sshsk_open(const char *path)
99{
100 struct sshsk_provider *ret = NULL;
101 uint32_t version;
102
103 if ((ret = calloc(1, sizeof(*ret))) == NULL) {
104 error("%s: calloc failed", __func__);
105 return NULL;
106 }
107 if ((ret->path = strdup(path)) == NULL) {
108 error("%s: strdup failed", __func__);
109 goto fail;
110 }
111 /* Skip the rest if we're using the linked in middleware */
112 if (strcasecmp(ret->path, "internal") == 0) {
113#ifdef ENABLE_SK_INTERNAL
114 ret->sk_enroll = ssh_sk_enroll;
115 ret->sk_sign = ssh_sk_sign;
116 ret->sk_load_resident_keys = ssh_sk_load_resident_keys;
117#else
118 error("internal security key support not enabled");
119#endif
120 return ret;
121 }
122 if ((ret->dlhandle = dlopen(path, RTLD_NOW)) == NULL) {
123 error("Provider \"%s\" dlopen failed: %s", path, dlerror());
124 goto fail;
125 }
126 if ((ret->sk_api_version = dlsym(ret->dlhandle,
127 "sk_api_version")) == NULL) {
128 error("Provider \"%s\" dlsym(sk_api_version) failed: %s",
129 path, dlerror());
130 goto fail;
131 }
132 version = ret->sk_api_version();
133 debug("%s: provider %s implements version 0x%08lx", __func__,
134 ret->path, (u_long)version);
135 if ((version & SSH_SK_VERSION_MAJOR_MASK) != SSH_SK_VERSION_MAJOR) {
136 error("Provider \"%s\" implements unsupported "
137 "version 0x%08lx (supported: 0x%08lx)",
138 path, (u_long)version, (u_long)SSH_SK_VERSION_MAJOR);
139 goto fail;
140 }
141 if ((ret->sk_enroll = dlsym(ret->dlhandle, "sk_enroll")) == NULL) {
142 error("Provider %s dlsym(sk_enroll) failed: %s",
143 path, dlerror());
144 goto fail;
145 }
146 if ((ret->sk_sign = dlsym(ret->dlhandle, "sk_sign")) == NULL) {
147 error("Provider \"%s\" dlsym(sk_sign) failed: %s",
148 path, dlerror());
149 goto fail;
150 }
151 if ((ret->sk_load_resident_keys = dlsym(ret->dlhandle,
152 "sk_load_resident_keys")) == NULL) {
153 error("Provider \"%s\" dlsym(sk_load_resident_keys) "
154 "failed: %s", path, dlerror());
155 goto fail;
156 }
157 /* success */
158 return ret;
159fail:
160 sshsk_free(ret);
161 return NULL;
162}
163
164static void
165sshsk_free_enroll_response(struct sk_enroll_response *r)
166{
167 if (r == NULL)
168 return;
169 freezero(r->key_handle, r->key_handle_len);
170 freezero(r->public_key, r->public_key_len);
171 freezero(r->signature, r->signature_len);
172 freezero(r->attestation_cert, r->attestation_cert_len);
173 freezero(r, sizeof(*r));
174}
175
176static void
177sshsk_free_sign_response(struct sk_sign_response *r)
178{
179 if (r == NULL)
180 return;
181 freezero(r->sig_r, r->sig_r_len);
182 freezero(r->sig_s, r->sig_s_len);
183 freezero(r, sizeof(*r));
184}
185
186#ifdef WITH_OPENSSL
187/* Assemble key from response */
188static int
189sshsk_ecdsa_assemble(struct sk_enroll_response *resp, struct sshkey **keyp)
190{
191 struct sshkey *key = NULL;
192 struct sshbuf *b = NULL;
193 EC_POINT *q = NULL;
194 int r;
195
196 *keyp = NULL;
197 if ((key = sshkey_new(KEY_ECDSA_SK)) == NULL) {
198 error("%s: sshkey_new failed", __func__);
199 r = SSH_ERR_ALLOC_FAIL;
200 goto out;
201 }
202 key->ecdsa_nid = NID_X9_62_prime256v1;
203 if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL ||
204 (q = EC_POINT_new(EC_KEY_get0_group(key->ecdsa))) == NULL ||
205 (b = sshbuf_new()) == NULL) {
206 error("%s: allocation failed", __func__);
207 r = SSH_ERR_ALLOC_FAIL;
208 goto out;
209 }
210 if ((r = sshbuf_put_string(b,
211 resp->public_key, resp->public_key_len)) != 0) {
212 error("%s: buffer error: %s", __func__, ssh_err(r));
213 goto out;
214 }
215 if ((r = sshbuf_get_ec(b, q, EC_KEY_get0_group(key->ecdsa))) != 0) {
216 error("%s: parse key: %s", __func__, ssh_err(r));
217 r = SSH_ERR_INVALID_FORMAT;
218 goto out;
219 }
220 if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa), q) != 0) {
221 error("Authenticator returned invalid ECDSA key");
222 r = SSH_ERR_KEY_INVALID_EC_VALUE;
223 goto out;
224 }
225 if (EC_KEY_set_public_key(key->ecdsa, q) != 1) {
226 /* XXX assume it is a allocation error */
227 error("%s: allocation failed", __func__);
228 r = SSH_ERR_ALLOC_FAIL;
229 goto out;
230 }
231 /* success */
232 *keyp = key;
233 key = NULL; /* transferred */
234 r = 0;
235 out:
236 EC_POINT_free(q);
237 sshkey_free(key);
238 sshbuf_free(b);
239 return r;
240}
241#endif /* WITH_OPENSSL */
242
243static int
244sshsk_ed25519_assemble(struct sk_enroll_response *resp, struct sshkey **keyp)
245{
246 struct sshkey *key = NULL;
247 int r;
248
249 *keyp = NULL;
250 if (resp->public_key_len != ED25519_PK_SZ) {
251 error("%s: invalid size: %zu", __func__, resp->public_key_len);
252 r = SSH_ERR_INVALID_FORMAT;
253 goto out;
254 }
255 if ((key = sshkey_new(KEY_ED25519_SK)) == NULL) {
256 error("%s: sshkey_new failed", __func__);
257 r = SSH_ERR_ALLOC_FAIL;
258 goto out;
259 }
260 if ((key->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) {
261 error("%s: malloc failed", __func__);
262 r = SSH_ERR_ALLOC_FAIL;
263 goto out;
264 }
265 memcpy(key->ed25519_pk, resp->public_key, ED25519_PK_SZ);
266 /* success */
267 *keyp = key;
268 key = NULL; /* transferred */
269 r = 0;
270 out:
271 sshkey_free(key);
272 return r;
273}
274
275static int
276sshsk_key_from_response(int alg, const char *application, uint8_t flags,
277 struct sk_enroll_response *resp, struct sshkey **keyp)
278{
279 struct sshkey *key = NULL;
280 int r = SSH_ERR_INTERNAL_ERROR;
281
282 *keyp = NULL;
283
284 /* Check response validity */
285 if (resp->public_key == NULL || resp->key_handle == NULL) {
286 error("%s: sk_enroll response invalid", __func__);
287 r = SSH_ERR_INVALID_FORMAT;
288 goto out;
289 }
290 switch (alg) {
291#ifdef WITH_OPENSSL
292 case SSH_SK_ECDSA:
293 if ((r = sshsk_ecdsa_assemble(resp, &key)) != 0)
294 goto out;
295 break;
296#endif /* WITH_OPENSSL */
297 case SSH_SK_ED25519:
298 if ((r = sshsk_ed25519_assemble(resp, &key)) != 0)
299 goto out;
300 break;
301 default:
302 error("%s: unsupported algorithm %d", __func__, alg);
303 r = SSH_ERR_INVALID_ARGUMENT;
304 goto out;
305 }
306 key->sk_flags = flags;
307 if ((key->sk_key_handle = sshbuf_new()) == NULL ||
308 (key->sk_reserved = sshbuf_new()) == NULL) {
309 error("%s: allocation failed", __func__);
310 r = SSH_ERR_ALLOC_FAIL;
311 goto out;
312 }
313 if ((key->sk_application = strdup(application)) == NULL) {
314 error("%s: strdup application failed", __func__);
315 r = SSH_ERR_ALLOC_FAIL;
316 goto out;
317 }
318 if ((r = sshbuf_put(key->sk_key_handle, resp->key_handle,
319 resp->key_handle_len)) != 0) {
320 error("%s: buffer error: %s", __func__, ssh_err(r));
321 goto out;
322 }
323 /* success */
324 r = 0;
325 *keyp = key;
326 key = NULL;
327 out:
328 sshkey_free(key);
329 return r;
330}
331
332static int
333skerr_to_ssherr(int skerr)
334{
335 switch (skerr) {
336 case SSH_SK_ERR_UNSUPPORTED:
337 return SSH_ERR_FEATURE_UNSUPPORTED;
338 case SSH_SK_ERR_PIN_REQUIRED:
339 return SSH_ERR_KEY_WRONG_PASSPHRASE;
340 case SSH_SK_ERR_DEVICE_NOT_FOUND:
341 return SSH_ERR_DEVICE_NOT_FOUND;
342 case SSH_SK_ERR_GENERAL:
343 default:
344 return SSH_ERR_INVALID_FORMAT;
345 }
346}
347
348static void
349sshsk_free_options(struct sk_option **opts)
350{
351 size_t i;
352
353 if (opts == NULL)
354 return;
355 for (i = 0; opts[i] != NULL; i++) {
356 free(opts[i]->name);
357 free(opts[i]->value);
358 free(opts[i]);
359 }
360 free(opts);
361}
362
363static int
364sshsk_add_option(struct sk_option ***optsp, size_t *noptsp,
365 const char *name, const char *value, uint8_t required)
366{
367 struct sk_option **opts = *optsp;
368 size_t nopts = *noptsp;
369
370 if ((opts = recallocarray(opts, nopts, nopts + 2, /* extra for NULL */
371 sizeof(*opts))) == NULL) {
372 error("%s: array alloc failed", __func__);
373 return SSH_ERR_ALLOC_FAIL;
374 }
375 *optsp = opts;
376 *noptsp = nopts + 1;
377 if ((opts[nopts] = calloc(1, sizeof(**opts))) == NULL) {
378 error("%s: alloc failed", __func__);
379 return SSH_ERR_ALLOC_FAIL;
380 }
381 if ((opts[nopts]->name = strdup(name)) == NULL ||
382 (opts[nopts]->value = strdup(value)) == NULL) {
383 error("%s: alloc failed", __func__);
384 return SSH_ERR_ALLOC_FAIL;
385 }
386 opts[nopts]->required = required;
387 return 0;
388}
389
390static int
391make_options(const char *device, const char *user_id,
392 struct sk_option ***optsp)
393{
394 struct sk_option **opts = NULL;
395 size_t nopts = 0;
396 int r, ret = SSH_ERR_INTERNAL_ERROR;
397
398 if (device != NULL &&
399 (r = sshsk_add_option(&opts, &nopts, "device", device, 0)) != 0) {
400 ret = r;
401 goto out;
402 }
403 if (user_id != NULL &&
404 (r = sshsk_add_option(&opts, &nopts, "user", user_id, 0)) != 0) {
405 ret = r;
406 goto out;
407 }
408 /* success */
409 *optsp = opts;
410 opts = NULL;
411 nopts = 0;
412 ret = 0;
413 out:
414 sshsk_free_options(opts);
415 return ret;
416}
417
418int
419sshsk_enroll(int type, const char *provider_path, const char *device,
420 const char *application, const char *userid, uint8_t flags,
421 const char *pin, struct sshbuf *challenge_buf,
422 struct sshkey **keyp, struct sshbuf *attest)
423{
424 struct sshsk_provider *skp = NULL;
425 struct sshkey *key = NULL;
426 u_char randchall[32];
427 const u_char *challenge;
428 size_t challenge_len;
429 struct sk_enroll_response *resp = NULL;
430 struct sk_option **opts = NULL;
431 int r = SSH_ERR_INTERNAL_ERROR;
432 int alg;
433
434 debug("%s: provider \"%s\", device \"%s\", application \"%s\", "
435 "userid \"%s\", flags 0x%02x, challenge len %zu%s", __func__,
436 provider_path, device, application, userid, flags,
437 challenge_buf == NULL ? 0 : sshbuf_len(challenge_buf),
438 (pin != NULL && *pin != '\0') ? " with-pin" : "");
439
440 *keyp = NULL;
441 if (attest)
442 sshbuf_reset(attest);
443
444 if ((r = make_options(device, userid, &opts)) != 0)
445 goto out;
446
447 switch (type) {
448#ifdef WITH_OPENSSL
449 case KEY_ECDSA_SK:
450 alg = SSH_SK_ECDSA;
451 break;
452#endif /* WITH_OPENSSL */
453 case KEY_ED25519_SK:
454 alg = SSH_SK_ED25519;
455 break;
456 default:
457 error("%s: unsupported key type", __func__);
458 r = SSH_ERR_INVALID_ARGUMENT;
459 goto out;
460 }
461 if (provider_path == NULL) {
462 error("%s: missing provider", __func__);
463 r = SSH_ERR_INVALID_ARGUMENT;
464 goto out;
465 }
466 if (application == NULL || *application == '\0') {
467 error("%s: missing application", __func__);
468 r = SSH_ERR_INVALID_ARGUMENT;
469 goto out;
470 }
471 if (challenge_buf == NULL) {
472 debug("%s: using random challenge", __func__);
473 arc4random_buf(randchall, sizeof(randchall));
474 challenge = randchall;
475 challenge_len = sizeof(randchall);
476 } else if (sshbuf_len(challenge_buf) == 0) {
477 error("Missing enrollment challenge");
478 r = SSH_ERR_INVALID_ARGUMENT;
479 goto out;
480 } else {
481 challenge = sshbuf_ptr(challenge_buf);
482 challenge_len = sshbuf_len(challenge_buf);
483 debug3("%s: using explicit challenge len=%zd",
484 __func__, challenge_len);
485 }
486 if ((skp = sshsk_open(provider_path)) == NULL) {
487 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */
488 goto out;
489 }
490 /* XXX validate flags? */
491 /* enroll key */
492 if ((r = skp->sk_enroll(alg, challenge, challenge_len, application,
493 flags, pin, opts, &resp)) != 0) {
494 debug("%s: provider \"%s\" returned failure %d", __func__,
495 provider_path, r);
496 r = skerr_to_ssherr(r);
497 goto out;
498 }
499
500 if ((r = sshsk_key_from_response(alg, application, flags,
501 resp, &key)) != 0)
502 goto out;
503
504 /* Optionally fill in the attestation information */
505 if (attest != NULL) {
506 if ((r = sshbuf_put_cstring(attest,
507 "ssh-sk-attest-v00")) != 0 ||
508 (r = sshbuf_put_string(attest,
509 resp->attestation_cert, resp->attestation_cert_len)) != 0 ||
510 (r = sshbuf_put_string(attest,
511 resp->signature, resp->signature_len)) != 0 ||
512 (r = sshbuf_put_u32(attest, 0)) != 0 || /* resvd flags */
513 (r = sshbuf_put_string(attest, NULL, 0)) != 0 /* resvd */) {
514 error("%s: buffer error: %s", __func__, ssh_err(r));
515 goto out;
516 }
517 }
518 /* success */
519 *keyp = key;
520 key = NULL; /* transferred */
521 r = 0;
522 out:
523 sshsk_free_options(opts);
524 sshsk_free(skp);
525 sshkey_free(key);
526 sshsk_free_enroll_response(resp);
527 explicit_bzero(randchall, sizeof(randchall));
528 return r;
529}
530
531#ifdef WITH_OPENSSL
532static int
533sshsk_ecdsa_sig(struct sk_sign_response *resp, struct sshbuf *sig)
534{
535 struct sshbuf *inner_sig = NULL;
536 int r = SSH_ERR_INTERNAL_ERROR;
537
538 /* Check response validity */
539 if (resp->sig_r == NULL || resp->sig_s == NULL) {
540 error("%s: sk_sign response invalid", __func__);
541 r = SSH_ERR_INVALID_FORMAT;
542 goto out;
543 }
544 if ((inner_sig = sshbuf_new()) == NULL) {
545 r = SSH_ERR_ALLOC_FAIL;
546 goto out;
547 }
548 /* Prepare and append inner signature object */
549 if ((r = sshbuf_put_bignum2_bytes(inner_sig,
550 resp->sig_r, resp->sig_r_len)) != 0 ||
551 (r = sshbuf_put_bignum2_bytes(inner_sig,
552 resp->sig_s, resp->sig_s_len)) != 0) {
553 debug("%s: buffer error: %s", __func__, ssh_err(r));
554 goto out;
555 }
556 if ((r = sshbuf_put_stringb(sig, inner_sig)) != 0 ||
557 (r = sshbuf_put_u8(sig, resp->flags)) != 0 ||
558 (r = sshbuf_put_u32(sig, resp->counter)) != 0) {
559 debug("%s: buffer error: %s", __func__, ssh_err(r));
560 goto out;
561 }
562#ifdef DEBUG_SK
563 fprintf(stderr, "%s: sig_r:\n", __func__);
564 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr);
565 fprintf(stderr, "%s: sig_s:\n", __func__);
566 sshbuf_dump_data(resp->sig_s, resp->sig_s_len, stderr);
567 fprintf(stderr, "%s: inner:\n", __func__);
568 sshbuf_dump(inner_sig, stderr);
569#endif
570 r = 0;
571 out:
572 sshbuf_free(inner_sig);
573 return r;
574}
575#endif /* WITH_OPENSSL */
576
577static int
578sshsk_ed25519_sig(struct sk_sign_response *resp, struct sshbuf *sig)
579{
580 int r = SSH_ERR_INTERNAL_ERROR;
581
582 /* Check response validity */
583 if (resp->sig_r == NULL) {
584 error("%s: sk_sign response invalid", __func__);
585 r = SSH_ERR_INVALID_FORMAT;
586 goto out;
587 }
588 if ((r = sshbuf_put_string(sig,
589 resp->sig_r, resp->sig_r_len)) != 0 ||
590 (r = sshbuf_put_u8(sig, resp->flags)) != 0 ||
591 (r = sshbuf_put_u32(sig, resp->counter)) != 0) {
592 debug("%s: buffer error: %s", __func__, ssh_err(r));
593 goto out;
594 }
595#ifdef DEBUG_SK
596 fprintf(stderr, "%s: sig_r:\n", __func__);
597 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr);
598#endif
599 r = 0;
600 out:
601 return 0;
602}
603
604int
605sshsk_sign(const char *provider_path, struct sshkey *key,
606 u_char **sigp, size_t *lenp, const u_char *data, size_t datalen,
607 u_int compat, const char *pin)
608{
609 struct sshsk_provider *skp = NULL;
610 int r = SSH_ERR_INTERNAL_ERROR;
611 int type, alg;
612 struct sk_sign_response *resp = NULL;
613 struct sshbuf *inner_sig = NULL, *sig = NULL;
614 uint8_t message[32];
615 struct sk_option **opts = NULL;
616
617 debug("%s: provider \"%s\", key %s, flags 0x%02x%s", __func__,
618 provider_path, sshkey_type(key), key->sk_flags,
619 (pin != NULL && *pin != '\0') ? " with-pin" : "");
620
621 if (sigp != NULL)
622 *sigp = NULL;
623 if (lenp != NULL)
624 *lenp = 0;
625 type = sshkey_type_plain(key->type);
626 switch (type) {
627#ifdef WITH_OPENSSL
628 case KEY_ECDSA_SK:
629 alg = SSH_SK_ECDSA;
630 break;
631#endif /* WITH_OPENSSL */
632 case KEY_ED25519_SK:
633 alg = SSH_SK_ED25519;
634 break;
635 default:
636 return SSH_ERR_INVALID_ARGUMENT;
637 }
638 if (provider_path == NULL ||
639 key->sk_key_handle == NULL ||
640 key->sk_application == NULL || *key->sk_application == '\0') {
641 r = SSH_ERR_INVALID_ARGUMENT;
642 goto out;
643 }
644 if ((skp = sshsk_open(provider_path)) == NULL) {
645 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */
646 goto out;
647 }
648
649 /* hash data to be signed before it goes to the security key */
650 if ((r = ssh_digest_memory(SSH_DIGEST_SHA256, data, datalen,
651 message, sizeof(message))) != 0) {
652 error("%s: hash application failed: %s", __func__, ssh_err(r));
653 r = SSH_ERR_INTERNAL_ERROR;
654 goto out;
655 }
656 if ((r = skp->sk_sign(alg, message, sizeof(message),
657 key->sk_application,
658 sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle),
659 key->sk_flags, pin, opts, &resp)) != 0) {
660 debug("%s: sk_sign failed with code %d", __func__, r);
661 r = skerr_to_ssherr(r);
662 goto out;
663 }
664 /* Assemble signature */
665 if ((sig = sshbuf_new()) == NULL) {
666 r = SSH_ERR_ALLOC_FAIL;
667 goto out;
668 }
669 if ((r = sshbuf_put_cstring(sig, sshkey_ssh_name_plain(key))) != 0) {
670 debug("%s: buffer error (outer): %s", __func__, ssh_err(r));
671 goto out;
672 }
673 switch (type) {
674#ifdef WITH_OPENSSL
675 case KEY_ECDSA_SK:
676 if ((r = sshsk_ecdsa_sig(resp, sig)) != 0)
677 goto out;
678 break;
679#endif /* WITH_OPENSSL */
680 case KEY_ED25519_SK:
681 if ((r = sshsk_ed25519_sig(resp, sig)) != 0)
682 goto out;
683 break;
684 }
685#ifdef DEBUG_SK
686 fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n",
687 __func__, resp->flags, resp->counter);
688 fprintf(stderr, "%s: hashed message:\n", __func__);
689 sshbuf_dump_data(message, sizeof(message), stderr);
690 fprintf(stderr, "%s: sigbuf:\n", __func__);
691 sshbuf_dump(sig, stderr);
692#endif
693 if (sigp != NULL) {
694 if ((*sigp = malloc(sshbuf_len(sig))) == NULL) {
695 r = SSH_ERR_ALLOC_FAIL;
696 goto out;
697 }
698 memcpy(*sigp, sshbuf_ptr(sig), sshbuf_len(sig));
699 }
700 if (lenp != NULL)
701 *lenp = sshbuf_len(sig);
702 /* success */
703 r = 0;
704 out:
705 sshsk_free_options(opts);
706 explicit_bzero(message, sizeof(message));
707 sshsk_free(skp);
708 sshsk_free_sign_response(resp);
709 sshbuf_free(sig);
710 sshbuf_free(inner_sig);
711 return r;
712}
713
714static void
715sshsk_free_sk_resident_keys(struct sk_resident_key **rks, size_t nrks)
716{
717 size_t i;
718
719 if (nrks == 0 || rks == NULL)
720 return;
721 for (i = 0; i < nrks; i++) {
722 free(rks[i]->application);
723 freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len);
724 freezero(rks[i]->key.public_key, rks[i]->key.public_key_len);
725 freezero(rks[i]->key.signature, rks[i]->key.signature_len);
726 freezero(rks[i]->key.attestation_cert,
727 rks[i]->key.attestation_cert_len);
728 freezero(rks[i], sizeof(**rks));
729 }
730 free(rks);
731}
732
733int
734sshsk_load_resident(const char *provider_path, const char *device,
735 const char *pin, struct sshkey ***keysp, size_t *nkeysp)
736{
737 struct sshsk_provider *skp = NULL;
738 int r = SSH_ERR_INTERNAL_ERROR;
739 struct sk_resident_key **rks = NULL;
740 size_t i, nrks = 0, nkeys = 0;
741 struct sshkey *key = NULL, **keys = NULL, **tmp;
742 uint8_t flags;
743 struct sk_option **opts = NULL;
744
745 debug("%s: provider \"%s\"%s", __func__, provider_path,
746 (pin != NULL && *pin != '\0') ? ", have-pin": "");
747
748 if (keysp == NULL || nkeysp == NULL)
749 return SSH_ERR_INVALID_ARGUMENT;
750 *keysp = NULL;
751 *nkeysp = 0;
752
753 if ((r = make_options(device, NULL, &opts)) != 0)
754 goto out;
755 if ((skp = sshsk_open(provider_path)) == NULL) {
756 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */
757 goto out;
758 }
759 if ((r = skp->sk_load_resident_keys(pin, opts, &rks, &nrks)) != 0) {
760 error("Provider \"%s\" returned failure %d", provider_path, r);
761 r = skerr_to_ssherr(r);
762 goto out;
763 }
764 for (i = 0; i < nrks; i++) {
765 debug3("%s: rk %zu: slot = %zu, alg = %d, application = \"%s\"",
766 __func__, i, rks[i]->slot, rks[i]->alg,
767 rks[i]->application);
768 /* XXX need better filter here */
769 if (strncmp(rks[i]->application, "ssh:", 4) != 0)
770 continue;
771 switch (rks[i]->alg) {
772 case SSH_SK_ECDSA:
773 case SSH_SK_ED25519:
774 break;
775 default:
776 continue;
777 }
778 /* XXX where to get flags? */
779 flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY;
780 if ((r = sshsk_key_from_response(rks[i]->alg,
781 rks[i]->application, flags, &rks[i]->key, &key)) != 0)
782 goto out;
783 if ((tmp = recallocarray(keys, nkeys, nkeys + 1,
784 sizeof(*tmp))) == NULL) {
785 error("%s: recallocarray failed", __func__);
786 r = SSH_ERR_ALLOC_FAIL;
787 goto out;
788 }
789 keys = tmp;
790 keys[nkeys++] = key;
791 key = NULL;
792 /* XXX synthesise comment */
793 }
794 /* success */
795 *keysp = keys;
796 *nkeysp = nkeys;
797 keys = NULL;
798 nkeys = 0;
799 r = 0;
800 out:
801 sshsk_free_options(opts);
802 sshsk_free(skp);
803 sshsk_free_sk_resident_keys(rks, nrks);
804 sshkey_free(key);
805 if (nkeys != 0) {
806 for (i = 0; i < nkeys; i++)
807 sshkey_free(keys[i]);
808 free(keys);
809 }
810 return r;
811}
812
813#endif /* ENABLE_SK */
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-02 11:12:32 +0000