ssh-sk.c revision 1.1.1.2
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 <dlfcn.h> 21 #include <stddef.h> 22 #include <stdint.h> 23 #include <string.h> 24 #include <stdio.h> 25 26 #ifdef WITH_OPENSSL 27 #include <openssl/objects.h> 28 #include <openssl/ec.h> 29 #endif /* WITH_OPENSSL */ 30 31 #include "log.h" 32 #include "misc.h" 33 #include "sshbuf.h" 34 #include "sshkey.h" 35 #include "ssherr.h" 36 #include "digest.h" 37 38 #include "ssh-sk.h" 39 #include "sk-api.h" 40 #include "crypto_api.h" 41 42 struct sshsk_provider { 43 char *path; 44 void *dlhandle; 45 46 /* Return the version of the middleware API */ 47 uint32_t (*sk_api_version)(void); 48 49 /* Enroll a U2F key (private key generation) */ 50 int (*sk_enroll)(int alg, const uint8_t *challenge, 51 size_t challenge_len, const char *application, uint8_t flags, 52 const char *pin, struct sk_option **opts, 53 struct sk_enroll_response **enroll_response); 54 55 /* Sign a challenge */ 56 int (*sk_sign)(int alg, const uint8_t *message, size_t message_len, 57 const char *application, 58 const uint8_t *key_handle, size_t key_handle_len, 59 uint8_t flags, const char *pin, struct sk_option **opts, 60 struct sk_sign_response **sign_response); 61 62 /* Enumerate resident keys */ 63 int (*sk_load_resident_keys)(const char *pin, struct sk_option **opts, 64 struct sk_resident_key ***rks, size_t *nrks); 65 }; 66 67 /* Built-in version */ 68 int ssh_sk_enroll(int alg, const uint8_t *challenge, 69 size_t challenge_len, const char *application, uint8_t flags, 70 const char *pin, struct sk_option **opts, 71 struct sk_enroll_response **enroll_response); 72 int ssh_sk_sign(int alg, const uint8_t *message, size_t message_len, 73 const char *application, 74 const uint8_t *key_handle, size_t key_handle_len, 75 uint8_t flags, const char *pin, struct sk_option **opts, 76 struct sk_sign_response **sign_response); 77 int ssh_sk_load_resident_keys(const char *pin, struct sk_option **opts, 78 struct sk_resident_key ***rks, size_t *nrks); 79 80 static void 81 sshsk_free(struct sshsk_provider *p) 82 { 83 if (p == NULL) 84 return; 85 free(p->path); 86 if (p->dlhandle != NULL) 87 dlclose(p->dlhandle); 88 free(p); 89 } 90 91 static struct sshsk_provider * 92 sshsk_open(const char *path) 93 { 94 struct sshsk_provider *ret = NULL; 95 uint32_t version; 96 97 if (path == NULL || *path == '\0') { 98 error("No FIDO SecurityKeyProvider specified"); 99 return NULL; 100 } 101 if ((ret = calloc(1, sizeof(*ret))) == NULL) { 102 error("%s: calloc failed", __func__); 103 return NULL; 104 } 105 if ((ret->path = strdup(path)) == NULL) { 106 error("%s: strdup failed", __func__); 107 goto fail; 108 } 109 /* Skip the rest if we're using the linked in middleware */ 110 if (strcasecmp(ret->path, "internal") == 0) { 111 ret->sk_enroll = ssh_sk_enroll; 112 ret->sk_sign = ssh_sk_sign; 113 ret->sk_load_resident_keys = ssh_sk_load_resident_keys; 114 return ret; 115 } 116 if ((ret->dlhandle = dlopen(path, RTLD_NOW)) == NULL) { 117 error("Provider \"%s\" dlopen failed: %s", path, dlerror()); 118 goto fail; 119 } 120 if ((ret->sk_api_version = dlsym(ret->dlhandle, 121 "sk_api_version")) == NULL) { 122 error("Provider \"%s\" dlsym(sk_api_version) failed: %s", 123 path, dlerror()); 124 goto fail; 125 } 126 version = ret->sk_api_version(); 127 debug("%s: provider %s implements version 0x%08lx", __func__, 128 ret->path, (u_long)version); 129 if ((version & SSH_SK_VERSION_MAJOR_MASK) != SSH_SK_VERSION_MAJOR) { 130 error("Provider \"%s\" implements unsupported " 131 "version 0x%08lx (supported: 0x%08lx)", 132 path, (u_long)version, (u_long)SSH_SK_VERSION_MAJOR); 133 goto fail; 134 } 135 if ((ret->sk_enroll = dlsym(ret->dlhandle, "sk_enroll")) == NULL) { 136 error("Provider %s dlsym(sk_enroll) failed: %s", 137 path, dlerror()); 138 goto fail; 139 } 140 if ((ret->sk_sign = dlsym(ret->dlhandle, "sk_sign")) == NULL) { 141 error("Provider \"%s\" dlsym(sk_sign) failed: %s", 142 path, dlerror()); 143 goto fail; 144 } 145 if ((ret->sk_load_resident_keys = dlsym(ret->dlhandle, 146 "sk_load_resident_keys")) == NULL) { 147 error("Provider \"%s\" dlsym(sk_load_resident_keys) " 148 "failed: %s", path, dlerror()); 149 goto fail; 150 } 151 /* success */ 152 return ret; 153 fail: 154 sshsk_free(ret); 155 return NULL; 156 } 157 158 static void 159 sshsk_free_enroll_response(struct sk_enroll_response *r) 160 { 161 if (r == NULL) 162 return; 163 freezero(r->key_handle, r->key_handle_len); 164 freezero(r->public_key, r->public_key_len); 165 freezero(r->signature, r->signature_len); 166 freezero(r->attestation_cert, r->attestation_cert_len); 167 freezero(r, sizeof(*r)); 168 } 169 170 static void 171 sshsk_free_sign_response(struct sk_sign_response *r) 172 { 173 if (r == NULL) 174 return; 175 freezero(r->sig_r, r->sig_r_len); 176 freezero(r->sig_s, r->sig_s_len); 177 freezero(r, sizeof(*r)); 178 } 179 180 #ifdef WITH_OPENSSL 181 /* Assemble key from response */ 182 static int 183 sshsk_ecdsa_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 184 { 185 struct sshkey *key = NULL; 186 struct sshbuf *b = NULL; 187 EC_POINT *q = NULL; 188 int r; 189 190 *keyp = NULL; 191 if ((key = sshkey_new(KEY_ECDSA_SK)) == NULL) { 192 error("%s: sshkey_new failed", __func__); 193 r = SSH_ERR_ALLOC_FAIL; 194 goto out; 195 } 196 key->ecdsa_nid = NID_X9_62_prime256v1; 197 if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL || 198 (q = EC_POINT_new(EC_KEY_get0_group(key->ecdsa))) == NULL || 199 (b = sshbuf_new()) == NULL) { 200 error("%s: allocation failed", __func__); 201 r = SSH_ERR_ALLOC_FAIL; 202 goto out; 203 } 204 if ((r = sshbuf_put_string(b, 205 resp->public_key, resp->public_key_len)) != 0) { 206 error("%s: buffer error: %s", __func__, ssh_err(r)); 207 goto out; 208 } 209 if ((r = sshbuf_get_ec(b, q, EC_KEY_get0_group(key->ecdsa))) != 0) { 210 error("%s: parse key: %s", __func__, ssh_err(r)); 211 r = SSH_ERR_INVALID_FORMAT; 212 goto out; 213 } 214 if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa), q) != 0) { 215 error("Authenticator returned invalid ECDSA key"); 216 r = SSH_ERR_KEY_INVALID_EC_VALUE; 217 goto out; 218 } 219 if (EC_KEY_set_public_key(key->ecdsa, q) != 1) { 220 /* XXX assume it is a allocation error */ 221 error("%s: allocation failed", __func__); 222 r = SSH_ERR_ALLOC_FAIL; 223 goto out; 224 } 225 /* success */ 226 *keyp = key; 227 key = NULL; /* transferred */ 228 r = 0; 229 out: 230 EC_POINT_free(q); 231 sshkey_free(key); 232 sshbuf_free(b); 233 return r; 234 } 235 #endif /* WITH_OPENSSL */ 236 237 static int 238 sshsk_ed25519_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 239 { 240 struct sshkey *key = NULL; 241 int r; 242 243 *keyp = NULL; 244 if (resp->public_key_len != ED25519_PK_SZ) { 245 error("%s: invalid size: %zu", __func__, resp->public_key_len); 246 r = SSH_ERR_INVALID_FORMAT; 247 goto out; 248 } 249 if ((key = sshkey_new(KEY_ED25519_SK)) == NULL) { 250 error("%s: sshkey_new failed", __func__); 251 r = SSH_ERR_ALLOC_FAIL; 252 goto out; 253 } 254 if ((key->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) { 255 error("%s: malloc failed", __func__); 256 r = SSH_ERR_ALLOC_FAIL; 257 goto out; 258 } 259 memcpy(key->ed25519_pk, resp->public_key, ED25519_PK_SZ); 260 /* success */ 261 *keyp = key; 262 key = NULL; /* transferred */ 263 r = 0; 264 out: 265 sshkey_free(key); 266 return r; 267 } 268 269 static int 270 sshsk_key_from_response(int alg, const char *application, uint8_t flags, 271 struct sk_enroll_response *resp, struct sshkey **keyp) 272 { 273 struct sshkey *key = NULL; 274 int r = SSH_ERR_INTERNAL_ERROR; 275 276 *keyp = NULL; 277 278 /* Check response validity */ 279 if (resp->public_key == NULL || resp->key_handle == NULL) { 280 error("%s: sk_enroll response invalid", __func__); 281 r = SSH_ERR_INVALID_FORMAT; 282 goto out; 283 } 284 switch (alg) { 285 #ifdef WITH_OPENSSL 286 case SSH_SK_ECDSA: 287 if ((r = sshsk_ecdsa_assemble(resp, &key)) != 0) 288 goto out; 289 break; 290 #endif /* WITH_OPENSSL */ 291 case SSH_SK_ED25519: 292 if ((r = sshsk_ed25519_assemble(resp, &key)) != 0) 293 goto out; 294 break; 295 default: 296 error("%s: unsupported algorithm %d", __func__, alg); 297 r = SSH_ERR_INVALID_ARGUMENT; 298 goto out; 299 } 300 key->sk_flags = flags; 301 if ((key->sk_key_handle = sshbuf_new()) == NULL || 302 (key->sk_reserved = sshbuf_new()) == NULL) { 303 error("%s: allocation failed", __func__); 304 r = SSH_ERR_ALLOC_FAIL; 305 goto out; 306 } 307 if ((key->sk_application = strdup(application)) == NULL) { 308 error("%s: strdup application failed", __func__); 309 r = SSH_ERR_ALLOC_FAIL; 310 goto out; 311 } 312 if ((r = sshbuf_put(key->sk_key_handle, resp->key_handle, 313 resp->key_handle_len)) != 0) { 314 error("%s: buffer error: %s", __func__, ssh_err(r)); 315 goto out; 316 } 317 /* success */ 318 r = 0; 319 *keyp = key; 320 key = NULL; 321 out: 322 sshkey_free(key); 323 return r; 324 } 325 326 static int 327 skerr_to_ssherr(int skerr) 328 { 329 switch (skerr) { 330 case SSH_SK_ERR_UNSUPPORTED: 331 return SSH_ERR_FEATURE_UNSUPPORTED; 332 case SSH_SK_ERR_PIN_REQUIRED: 333 return SSH_ERR_KEY_WRONG_PASSPHRASE; 334 case SSH_SK_ERR_DEVICE_NOT_FOUND: 335 return SSH_ERR_DEVICE_NOT_FOUND; 336 case SSH_SK_ERR_GENERAL: 337 default: 338 return SSH_ERR_INVALID_FORMAT; 339 } 340 } 341 342 static void 343 sshsk_free_options(struct sk_option **opts) 344 { 345 size_t i; 346 347 if (opts == NULL) 348 return; 349 for (i = 0; opts[i] != NULL; i++) { 350 free(opts[i]->name); 351 free(opts[i]->value); 352 free(opts[i]); 353 } 354 free(opts); 355 } 356 357 static int 358 sshsk_add_option(struct sk_option ***optsp, size_t *noptsp, 359 const char *name, const char *value, uint8_t required) 360 { 361 struct sk_option **opts = *optsp; 362 size_t nopts = *noptsp; 363 364 if ((opts = recallocarray(opts, nopts, nopts + 2, /* extra for NULL */ 365 sizeof(*opts))) == NULL) { 366 error("%s: array alloc failed", __func__); 367 return SSH_ERR_ALLOC_FAIL; 368 } 369 *optsp = opts; 370 *noptsp = nopts + 1; 371 if ((opts[nopts] = calloc(1, sizeof(**opts))) == NULL) { 372 error("%s: alloc failed", __func__); 373 return SSH_ERR_ALLOC_FAIL; 374 } 375 if ((opts[nopts]->name = strdup(name)) == NULL || 376 (opts[nopts]->value = strdup(value)) == NULL) { 377 error("%s: alloc failed", __func__); 378 return SSH_ERR_ALLOC_FAIL; 379 } 380 opts[nopts]->required = required; 381 return 0; 382 } 383 384 static int 385 make_options(const char *device, const char *user_id, 386 struct sk_option ***optsp) 387 { 388 struct sk_option **opts = NULL; 389 size_t nopts = 0; 390 int r, ret = SSH_ERR_INTERNAL_ERROR; 391 392 if (device != NULL && 393 (r = sshsk_add_option(&opts, &nopts, "device", device, 0)) != 0) { 394 ret = r; 395 goto out; 396 } 397 if (user_id != NULL && 398 (r = sshsk_add_option(&opts, &nopts, "user", user_id, 0)) != 0) { 399 ret = r; 400 goto out; 401 } 402 /* success */ 403 *optsp = opts; 404 opts = NULL; 405 nopts = 0; 406 ret = 0; 407 out: 408 sshsk_free_options(opts); 409 return ret; 410 } 411 412 int 413 sshsk_enroll(int type, const char *provider_path, const char *device, 414 const char *application, const char *userid, uint8_t flags, 415 const char *pin, struct sshbuf *challenge_buf, 416 struct sshkey **keyp, struct sshbuf *attest) 417 { 418 struct sshsk_provider *skp = NULL; 419 struct sshkey *key = NULL; 420 u_char randchall[32]; 421 const u_char *challenge; 422 size_t challenge_len; 423 struct sk_enroll_response *resp = NULL; 424 struct sk_option **opts = NULL; 425 int r = SSH_ERR_INTERNAL_ERROR; 426 int alg; 427 428 debug("%s: provider \"%s\", device \"%s\", application \"%s\", " 429 "userid \"%s\", flags 0x%02x, challenge len %zu%s", __func__, 430 provider_path, device, application, userid, flags, 431 challenge_buf == NULL ? 0 : sshbuf_len(challenge_buf), 432 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 433 434 *keyp = NULL; 435 if (attest) 436 sshbuf_reset(attest); 437 438 if ((r = make_options(device, userid, &opts)) != 0) 439 goto out; 440 441 switch (type) { 442 #ifdef WITH_OPENSSL 443 case KEY_ECDSA_SK: 444 alg = SSH_SK_ECDSA; 445 break; 446 #endif /* WITH_OPENSSL */ 447 case KEY_ED25519_SK: 448 alg = SSH_SK_ED25519; 449 break; 450 default: 451 error("%s: unsupported key type", __func__); 452 r = SSH_ERR_INVALID_ARGUMENT; 453 goto out; 454 } 455 if (provider_path == NULL) { 456 error("%s: missing provider", __func__); 457 r = SSH_ERR_INVALID_ARGUMENT; 458 goto out; 459 } 460 if (application == NULL || *application == '\0') { 461 error("%s: missing application", __func__); 462 r = SSH_ERR_INVALID_ARGUMENT; 463 goto out; 464 } 465 if (challenge_buf == NULL) { 466 debug("%s: using random challenge", __func__); 467 arc4random_buf(randchall, sizeof(randchall)); 468 challenge = randchall; 469 challenge_len = sizeof(randchall); 470 } else if (sshbuf_len(challenge_buf) == 0) { 471 error("Missing enrollment challenge"); 472 r = SSH_ERR_INVALID_ARGUMENT; 473 goto out; 474 } else { 475 challenge = sshbuf_ptr(challenge_buf); 476 challenge_len = sshbuf_len(challenge_buf); 477 debug3("%s: using explicit challenge len=%zd", 478 __func__, challenge_len); 479 } 480 if ((skp = sshsk_open(provider_path)) == NULL) { 481 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 482 goto out; 483 } 484 /* XXX validate flags? */ 485 /* enroll key */ 486 if ((r = skp->sk_enroll(alg, challenge, challenge_len, application, 487 flags, pin, opts, &resp)) != 0) { 488 debug("%s: provider \"%s\" returned failure %d", __func__, 489 provider_path, r); 490 r = skerr_to_ssherr(r); 491 goto out; 492 } 493 494 if ((r = sshsk_key_from_response(alg, application, flags, 495 resp, &key)) != 0) 496 goto out; 497 498 /* Optionally fill in the attestation information */ 499 if (attest != NULL) { 500 if ((r = sshbuf_put_cstring(attest, 501 "ssh-sk-attest-v00")) != 0 || 502 (r = sshbuf_put_string(attest, 503 resp->attestation_cert, resp->attestation_cert_len)) != 0 || 504 (r = sshbuf_put_string(attest, 505 resp->signature, resp->signature_len)) != 0 || 506 (r = sshbuf_put_u32(attest, 0)) != 0 || /* resvd flags */ 507 (r = sshbuf_put_string(attest, NULL, 0)) != 0 /* resvd */) { 508 error("%s: buffer error: %s", __func__, ssh_err(r)); 509 goto out; 510 } 511 } 512 /* success */ 513 *keyp = key; 514 key = NULL; /* transferred */ 515 r = 0; 516 out: 517 sshsk_free_options(opts); 518 sshsk_free(skp); 519 sshkey_free(key); 520 sshsk_free_enroll_response(resp); 521 explicit_bzero(randchall, sizeof(randchall)); 522 return r; 523 } 524 525 #ifdef WITH_OPENSSL 526 static int 527 sshsk_ecdsa_sig(struct sk_sign_response *resp, struct sshbuf *sig) 528 { 529 struct sshbuf *inner_sig = NULL; 530 int r = SSH_ERR_INTERNAL_ERROR; 531 532 /* Check response validity */ 533 if (resp->sig_r == NULL || resp->sig_s == NULL) { 534 error("%s: sk_sign response invalid", __func__); 535 r = SSH_ERR_INVALID_FORMAT; 536 goto out; 537 } 538 if ((inner_sig = sshbuf_new()) == NULL) { 539 r = SSH_ERR_ALLOC_FAIL; 540 goto out; 541 } 542 /* Prepare and append inner signature object */ 543 if ((r = sshbuf_put_bignum2_bytes(inner_sig, 544 resp->sig_r, resp->sig_r_len)) != 0 || 545 (r = sshbuf_put_bignum2_bytes(inner_sig, 546 resp->sig_s, resp->sig_s_len)) != 0) { 547 debug("%s: buffer error: %s", __func__, ssh_err(r)); 548 goto out; 549 } 550 if ((r = sshbuf_put_stringb(sig, inner_sig)) != 0 || 551 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 552 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 553 debug("%s: buffer error: %s", __func__, ssh_err(r)); 554 goto out; 555 } 556 #ifdef DEBUG_SK 557 fprintf(stderr, "%s: sig_r:\n", __func__); 558 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 559 fprintf(stderr, "%s: sig_s:\n", __func__); 560 sshbuf_dump_data(resp->sig_s, resp->sig_s_len, stderr); 561 fprintf(stderr, "%s: inner:\n", __func__); 562 sshbuf_dump(inner_sig, stderr); 563 #endif 564 r = 0; 565 out: 566 sshbuf_free(inner_sig); 567 return r; 568 } 569 #endif /* WITH_OPENSSL */ 570 571 static int 572 sshsk_ed25519_sig(struct sk_sign_response *resp, struct sshbuf *sig) 573 { 574 int r = SSH_ERR_INTERNAL_ERROR; 575 576 /* Check response validity */ 577 if (resp->sig_r == NULL) { 578 error("%s: sk_sign response invalid", __func__); 579 r = SSH_ERR_INVALID_FORMAT; 580 goto out; 581 } 582 if ((r = sshbuf_put_string(sig, 583 resp->sig_r, resp->sig_r_len)) != 0 || 584 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 585 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 586 debug("%s: buffer error: %s", __func__, ssh_err(r)); 587 goto out; 588 } 589 #ifdef DEBUG_SK 590 fprintf(stderr, "%s: sig_r:\n", __func__); 591 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 592 #endif 593 r = 0; 594 out: 595 return r; 596 } 597 598 int 599 sshsk_sign(const char *provider_path, struct sshkey *key, 600 u_char **sigp, size_t *lenp, const u_char *data, size_t datalen, 601 u_int compat, const char *pin) 602 { 603 struct sshsk_provider *skp = NULL; 604 int r = SSH_ERR_INTERNAL_ERROR; 605 int type, alg; 606 struct sk_sign_response *resp = NULL; 607 struct sshbuf *inner_sig = NULL, *sig = NULL; 608 struct sk_option **opts = NULL; 609 610 debug("%s: provider \"%s\", key %s, flags 0x%02x%s", __func__, 611 provider_path, sshkey_type(key), key->sk_flags, 612 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 613 614 if (sigp != NULL) 615 *sigp = NULL; 616 if (lenp != NULL) 617 *lenp = 0; 618 type = sshkey_type_plain(key->type); 619 switch (type) { 620 #ifdef WITH_OPENSSL 621 case KEY_ECDSA_SK: 622 alg = SSH_SK_ECDSA; 623 break; 624 #endif /* WITH_OPENSSL */ 625 case KEY_ED25519_SK: 626 alg = SSH_SK_ED25519; 627 break; 628 default: 629 return SSH_ERR_INVALID_ARGUMENT; 630 } 631 if (provider_path == NULL || 632 key->sk_key_handle == NULL || 633 key->sk_application == NULL || *key->sk_application == '\0') { 634 r = SSH_ERR_INVALID_ARGUMENT; 635 goto out; 636 } 637 if ((skp = sshsk_open(provider_path)) == NULL) { 638 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 639 goto out; 640 } 641 642 if ((r = skp->sk_sign(alg, data, datalen, key->sk_application, 643 sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle), 644 key->sk_flags, pin, opts, &resp)) != 0) { 645 debug("%s: sk_sign failed with code %d", __func__, r); 646 r = skerr_to_ssherr(r); 647 goto out; 648 } 649 /* Assemble signature */ 650 if ((sig = sshbuf_new()) == NULL) { 651 r = SSH_ERR_ALLOC_FAIL; 652 goto out; 653 } 654 if ((r = sshbuf_put_cstring(sig, sshkey_ssh_name_plain(key))) != 0) { 655 debug("%s: buffer error (outer): %s", __func__, ssh_err(r)); 656 goto out; 657 } 658 switch (type) { 659 #ifdef WITH_OPENSSL 660 case KEY_ECDSA_SK: 661 if ((r = sshsk_ecdsa_sig(resp, sig)) != 0) 662 goto out; 663 break; 664 #endif /* WITH_OPENSSL */ 665 case KEY_ED25519_SK: 666 if ((r = sshsk_ed25519_sig(resp, sig)) != 0) 667 goto out; 668 break; 669 } 670 #ifdef DEBUG_SK 671 fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n", 672 __func__, resp->flags, resp->counter); 673 fprintf(stderr, "%s: hashed message:\n", __func__); 674 sshbuf_dump_data(message, sizeof(message), stderr); 675 fprintf(stderr, "%s: sigbuf:\n", __func__); 676 sshbuf_dump(sig, stderr); 677 #endif 678 if (sigp != NULL) { 679 if ((*sigp = malloc(sshbuf_len(sig))) == NULL) { 680 r = SSH_ERR_ALLOC_FAIL; 681 goto out; 682 } 683 memcpy(*sigp, sshbuf_ptr(sig), sshbuf_len(sig)); 684 } 685 if (lenp != NULL) 686 *lenp = sshbuf_len(sig); 687 /* success */ 688 r = 0; 689 out: 690 sshsk_free_options(opts); 691 sshsk_free(skp); 692 sshsk_free_sign_response(resp); 693 sshbuf_free(sig); 694 sshbuf_free(inner_sig); 695 return r; 696 } 697 698 static void 699 sshsk_free_sk_resident_keys(struct sk_resident_key **rks, size_t nrks) 700 { 701 size_t i; 702 703 if (nrks == 0 || rks == NULL) 704 return; 705 for (i = 0; i < nrks; i++) { 706 free(rks[i]->application); 707 freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len); 708 freezero(rks[i]->key.public_key, rks[i]->key.public_key_len); 709 freezero(rks[i]->key.signature, rks[i]->key.signature_len); 710 freezero(rks[i]->key.attestation_cert, 711 rks[i]->key.attestation_cert_len); 712 freezero(rks[i], sizeof(**rks)); 713 } 714 free(rks); 715 } 716 717 int 718 sshsk_load_resident(const char *provider_path, const char *device, 719 const char *pin, struct sshkey ***keysp, size_t *nkeysp) 720 { 721 struct sshsk_provider *skp = NULL; 722 int r = SSH_ERR_INTERNAL_ERROR; 723 struct sk_resident_key **rks = NULL; 724 size_t i, nrks = 0, nkeys = 0; 725 struct sshkey *key = NULL, **keys = NULL, **tmp; 726 uint8_t flags; 727 struct sk_option **opts = NULL; 728 729 debug("%s: provider \"%s\"%s", __func__, provider_path, 730 (pin != NULL && *pin != '\0') ? ", have-pin": ""); 731 732 if (keysp == NULL || nkeysp == NULL) 733 return SSH_ERR_INVALID_ARGUMENT; 734 *keysp = NULL; 735 *nkeysp = 0; 736 737 if ((r = make_options(device, NULL, &opts)) != 0) 738 goto out; 739 if ((skp = sshsk_open(provider_path)) == NULL) { 740 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 741 goto out; 742 } 743 if ((r = skp->sk_load_resident_keys(pin, opts, &rks, &nrks)) != 0) { 744 error("Provider \"%s\" returned failure %d", provider_path, r); 745 r = skerr_to_ssherr(r); 746 goto out; 747 } 748 for (i = 0; i < nrks; i++) { 749 debug3("%s: rk %zu: slot = %zu, alg = %d, application = \"%s\"", 750 __func__, i, rks[i]->slot, rks[i]->alg, 751 rks[i]->application); 752 /* XXX need better filter here */ 753 if (strncmp(rks[i]->application, "ssh:", 4) != 0) 754 continue; 755 switch (rks[i]->alg) { 756 case SSH_SK_ECDSA: 757 case SSH_SK_ED25519: 758 break; 759 default: 760 continue; 761 } 762 /* XXX where to get flags? */ 763 flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY; 764 if ((r = sshsk_key_from_response(rks[i]->alg, 765 rks[i]->application, flags, &rks[i]->key, &key)) != 0) 766 goto out; 767 if ((tmp = recallocarray(keys, nkeys, nkeys + 1, 768 sizeof(*tmp))) == NULL) { 769 error("%s: recallocarray failed", __func__); 770 r = SSH_ERR_ALLOC_FAIL; 771 goto out; 772 } 773 keys = tmp; 774 keys[nkeys++] = key; 775 key = NULL; 776 /* XXX synthesise comment */ 777 } 778 /* success */ 779 *keysp = keys; 780 *nkeysp = nkeys; 781 keys = NULL; 782 nkeys = 0; 783 r = 0; 784 out: 785 sshsk_free_options(opts); 786 sshsk_free(skp); 787 sshsk_free_sk_resident_keys(rks, nrks); 788 sshkey_free(key); 789 if (nkeys != 0) { 790 for (i = 0; i < nkeys; i++) 791 sshkey_free(keys[i]); 792 free(keys); 793 } 794 return r; 795 } 796 797
Indexes created Mon Mar 16 00:23:04 UTC 2026