ssh-sk.c revision 1.1.1.3
1 /* $OpenBSD: ssh-sk.c,v 1.32 2020/09/09 03:08:02 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->authdata, r->authdata_len); 168 freezero(r, sizeof(*r)); 169 } 170 171 static void 172 sshsk_free_sign_response(struct sk_sign_response *r) 173 { 174 if (r == NULL) 175 return; 176 freezero(r->sig_r, r->sig_r_len); 177 freezero(r->sig_s, r->sig_s_len); 178 freezero(r, sizeof(*r)); 179 } 180 181 #ifdef WITH_OPENSSL 182 /* Assemble key from response */ 183 static int 184 sshsk_ecdsa_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 185 { 186 struct sshkey *key = NULL; 187 struct sshbuf *b = NULL; 188 EC_POINT *q = NULL; 189 int r; 190 191 *keyp = NULL; 192 if ((key = sshkey_new(KEY_ECDSA_SK)) == NULL) { 193 error("%s: sshkey_new failed", __func__); 194 r = SSH_ERR_ALLOC_FAIL; 195 goto out; 196 } 197 key->ecdsa_nid = NID_X9_62_prime256v1; 198 if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL || 199 (q = EC_POINT_new(EC_KEY_get0_group(key->ecdsa))) == NULL || 200 (b = sshbuf_new()) == NULL) { 201 error("%s: allocation failed", __func__); 202 r = SSH_ERR_ALLOC_FAIL; 203 goto out; 204 } 205 if ((r = sshbuf_put_string(b, 206 resp->public_key, resp->public_key_len)) != 0) { 207 error("%s: buffer error: %s", __func__, ssh_err(r)); 208 goto out; 209 } 210 if ((r = sshbuf_get_ec(b, q, EC_KEY_get0_group(key->ecdsa))) != 0) { 211 error("%s: parse key: %s", __func__, ssh_err(r)); 212 r = SSH_ERR_INVALID_FORMAT; 213 goto out; 214 } 215 if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa), q) != 0) { 216 error("Authenticator returned invalid ECDSA key"); 217 r = SSH_ERR_KEY_INVALID_EC_VALUE; 218 goto out; 219 } 220 if (EC_KEY_set_public_key(key->ecdsa, q) != 1) { 221 /* XXX assume it is a allocation error */ 222 error("%s: allocation failed", __func__); 223 r = SSH_ERR_ALLOC_FAIL; 224 goto out; 225 } 226 /* success */ 227 *keyp = key; 228 key = NULL; /* transferred */ 229 r = 0; 230 out: 231 EC_POINT_free(q); 232 sshkey_free(key); 233 sshbuf_free(b); 234 return r; 235 } 236 #endif /* WITH_OPENSSL */ 237 238 static int 239 sshsk_ed25519_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 240 { 241 struct sshkey *key = NULL; 242 int r; 243 244 *keyp = NULL; 245 if (resp->public_key_len != ED25519_PK_SZ) { 246 error("%s: invalid size: %zu", __func__, resp->public_key_len); 247 r = SSH_ERR_INVALID_FORMAT; 248 goto out; 249 } 250 if ((key = sshkey_new(KEY_ED25519_SK)) == NULL) { 251 error("%s: sshkey_new failed", __func__); 252 r = SSH_ERR_ALLOC_FAIL; 253 goto out; 254 } 255 if ((key->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) { 256 error("%s: malloc failed", __func__); 257 r = SSH_ERR_ALLOC_FAIL; 258 goto out; 259 } 260 memcpy(key->ed25519_pk, resp->public_key, ED25519_PK_SZ); 261 /* success */ 262 *keyp = key; 263 key = NULL; /* transferred */ 264 r = 0; 265 out: 266 sshkey_free(key); 267 return r; 268 } 269 270 static int 271 sshsk_key_from_response(int alg, const char *application, uint8_t flags, 272 struct sk_enroll_response *resp, struct sshkey **keyp) 273 { 274 struct sshkey *key = NULL; 275 int r = SSH_ERR_INTERNAL_ERROR; 276 277 *keyp = NULL; 278 279 /* Check response validity */ 280 if (resp->public_key == NULL || resp->key_handle == NULL) { 281 error("%s: sk_enroll response invalid", __func__); 282 r = SSH_ERR_INVALID_FORMAT; 283 goto out; 284 } 285 switch (alg) { 286 #ifdef WITH_OPENSSL 287 case SSH_SK_ECDSA: 288 if ((r = sshsk_ecdsa_assemble(resp, &key)) != 0) 289 goto out; 290 break; 291 #endif /* WITH_OPENSSL */ 292 case SSH_SK_ED25519: 293 if ((r = sshsk_ed25519_assemble(resp, &key)) != 0) 294 goto out; 295 break; 296 default: 297 error("%s: unsupported algorithm %d", __func__, alg); 298 r = SSH_ERR_INVALID_ARGUMENT; 299 goto out; 300 } 301 key->sk_flags = flags; 302 if ((key->sk_key_handle = sshbuf_new()) == NULL || 303 (key->sk_reserved = sshbuf_new()) == NULL) { 304 error("%s: allocation failed", __func__); 305 r = SSH_ERR_ALLOC_FAIL; 306 goto out; 307 } 308 if ((key->sk_application = strdup(application)) == NULL) { 309 error("%s: strdup application failed", __func__); 310 r = SSH_ERR_ALLOC_FAIL; 311 goto out; 312 } 313 if ((r = sshbuf_put(key->sk_key_handle, resp->key_handle, 314 resp->key_handle_len)) != 0) { 315 error("%s: buffer error: %s", __func__, ssh_err(r)); 316 goto out; 317 } 318 /* success */ 319 r = 0; 320 *keyp = key; 321 key = NULL; 322 out: 323 sshkey_free(key); 324 return r; 325 } 326 327 static int 328 skerr_to_ssherr(int skerr) 329 { 330 switch (skerr) { 331 case SSH_SK_ERR_UNSUPPORTED: 332 return SSH_ERR_FEATURE_UNSUPPORTED; 333 case SSH_SK_ERR_PIN_REQUIRED: 334 return SSH_ERR_KEY_WRONG_PASSPHRASE; 335 case SSH_SK_ERR_DEVICE_NOT_FOUND: 336 return SSH_ERR_DEVICE_NOT_FOUND; 337 case SSH_SK_ERR_GENERAL: 338 default: 339 return SSH_ERR_INVALID_FORMAT; 340 } 341 } 342 343 static void 344 sshsk_free_options(struct sk_option **opts) 345 { 346 size_t i; 347 348 if (opts == NULL) 349 return; 350 for (i = 0; opts[i] != NULL; i++) { 351 free(opts[i]->name); 352 free(opts[i]->value); 353 free(opts[i]); 354 } 355 free(opts); 356 } 357 358 static int 359 sshsk_add_option(struct sk_option ***optsp, size_t *noptsp, 360 const char *name, const char *value, uint8_t required) 361 { 362 struct sk_option **opts = *optsp; 363 size_t nopts = *noptsp; 364 365 if ((opts = recallocarray(opts, nopts, nopts + 2, /* extra for NULL */ 366 sizeof(*opts))) == NULL) { 367 error("%s: array alloc failed", __func__); 368 return SSH_ERR_ALLOC_FAIL; 369 } 370 *optsp = opts; 371 *noptsp = nopts + 1; 372 if ((opts[nopts] = calloc(1, sizeof(**opts))) == NULL) { 373 error("%s: alloc failed", __func__); 374 return SSH_ERR_ALLOC_FAIL; 375 } 376 if ((opts[nopts]->name = strdup(name)) == NULL || 377 (opts[nopts]->value = strdup(value)) == NULL) { 378 error("%s: alloc failed", __func__); 379 return SSH_ERR_ALLOC_FAIL; 380 } 381 opts[nopts]->required = required; 382 return 0; 383 } 384 385 static int 386 make_options(const char *device, const char *user_id, 387 struct sk_option ***optsp) 388 { 389 struct sk_option **opts = NULL; 390 size_t nopts = 0; 391 int r, ret = SSH_ERR_INTERNAL_ERROR; 392 393 if (device != NULL && 394 (r = sshsk_add_option(&opts, &nopts, "device", device, 0)) != 0) { 395 ret = r; 396 goto out; 397 } 398 if (user_id != NULL && 399 (r = sshsk_add_option(&opts, &nopts, "user", user_id, 0)) != 0) { 400 ret = r; 401 goto out; 402 } 403 /* success */ 404 *optsp = opts; 405 opts = NULL; 406 nopts = 0; 407 ret = 0; 408 out: 409 sshsk_free_options(opts); 410 return ret; 411 } 412 413 414 static int 415 fill_attestation_blob(const struct sk_enroll_response *resp, 416 struct sshbuf *attest) 417 { 418 int r; 419 420 if (attest == NULL) 421 return 0; /* nothing to do */ 422 if ((r = sshbuf_put_cstring(attest, "ssh-sk-attest-v01")) != 0 || 423 (r = sshbuf_put_string(attest, 424 resp->attestation_cert, resp->attestation_cert_len)) != 0 || 425 (r = sshbuf_put_string(attest, 426 resp->signature, resp->signature_len)) != 0 || 427 (r = sshbuf_put_string(attest, 428 resp->authdata, resp->authdata_len)) != 0 || 429 (r = sshbuf_put_u32(attest, 0)) != 0 || /* resvd flags */ 430 (r = sshbuf_put_string(attest, NULL, 0)) != 0 /* resvd */) { 431 error("%s: buffer error: %s", __func__, ssh_err(r)); 432 return r; 433 } 434 /* success */ 435 return 0; 436 } 437 438 int 439 sshsk_enroll(int type, const char *provider_path, const char *device, 440 const char *application, const char *userid, uint8_t flags, 441 const char *pin, struct sshbuf *challenge_buf, 442 struct sshkey **keyp, struct sshbuf *attest) 443 { 444 struct sshsk_provider *skp = NULL; 445 struct sshkey *key = NULL; 446 u_char randchall[32]; 447 const u_char *challenge; 448 size_t challenge_len; 449 struct sk_enroll_response *resp = NULL; 450 struct sk_option **opts = NULL; 451 int r = SSH_ERR_INTERNAL_ERROR; 452 int alg; 453 454 debug("%s: provider \"%s\", device \"%s\", application \"%s\", " 455 "userid \"%s\", flags 0x%02x, challenge len %zu%s", __func__, 456 provider_path, device, application, userid, flags, 457 challenge_buf == NULL ? 0 : sshbuf_len(challenge_buf), 458 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 459 460 *keyp = NULL; 461 if (attest) 462 sshbuf_reset(attest); 463 464 if ((r = make_options(device, userid, &opts)) != 0) 465 goto out; 466 467 switch (type) { 468 #ifdef WITH_OPENSSL 469 case KEY_ECDSA_SK: 470 alg = SSH_SK_ECDSA; 471 break; 472 #endif /* WITH_OPENSSL */ 473 case KEY_ED25519_SK: 474 alg = SSH_SK_ED25519; 475 break; 476 default: 477 error("%s: unsupported key type", __func__); 478 r = SSH_ERR_INVALID_ARGUMENT; 479 goto out; 480 } 481 if (provider_path == NULL) { 482 error("%s: missing provider", __func__); 483 r = SSH_ERR_INVALID_ARGUMENT; 484 goto out; 485 } 486 if (application == NULL || *application == '\0') { 487 error("%s: missing application", __func__); 488 r = SSH_ERR_INVALID_ARGUMENT; 489 goto out; 490 } 491 if (challenge_buf == NULL) { 492 debug("%s: using random challenge", __func__); 493 arc4random_buf(randchall, sizeof(randchall)); 494 challenge = randchall; 495 challenge_len = sizeof(randchall); 496 } else if (sshbuf_len(challenge_buf) == 0) { 497 error("Missing enrollment challenge"); 498 r = SSH_ERR_INVALID_ARGUMENT; 499 goto out; 500 } else { 501 challenge = sshbuf_ptr(challenge_buf); 502 challenge_len = sshbuf_len(challenge_buf); 503 debug3("%s: using explicit challenge len=%zd", 504 __func__, challenge_len); 505 } 506 if ((skp = sshsk_open(provider_path)) == NULL) { 507 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 508 goto out; 509 } 510 /* XXX validate flags? */ 511 /* enroll key */ 512 if ((r = skp->sk_enroll(alg, challenge, challenge_len, application, 513 flags, pin, opts, &resp)) != 0) { 514 debug("%s: provider \"%s\" returned failure %d", __func__, 515 provider_path, r); 516 r = skerr_to_ssherr(r); 517 goto out; 518 } 519 520 if ((r = sshsk_key_from_response(alg, application, flags, 521 resp, &key)) != 0) 522 goto out; 523 524 /* Optionally fill in the attestation information */ 525 if ((r = fill_attestation_blob(resp, attest)) != 0) 526 goto out; 527 528 /* success */ 529 *keyp = key; 530 key = NULL; /* transferred */ 531 r = 0; 532 out: 533 sshsk_free_options(opts); 534 sshsk_free(skp); 535 sshkey_free(key); 536 sshsk_free_enroll_response(resp); 537 explicit_bzero(randchall, sizeof(randchall)); 538 return r; 539 } 540 541 #ifdef WITH_OPENSSL 542 static int 543 sshsk_ecdsa_sig(struct sk_sign_response *resp, struct sshbuf *sig) 544 { 545 struct sshbuf *inner_sig = NULL; 546 int r = SSH_ERR_INTERNAL_ERROR; 547 548 /* Check response validity */ 549 if (resp->sig_r == NULL || resp->sig_s == NULL) { 550 error("%s: sk_sign response invalid", __func__); 551 r = SSH_ERR_INVALID_FORMAT; 552 goto out; 553 } 554 if ((inner_sig = sshbuf_new()) == NULL) { 555 r = SSH_ERR_ALLOC_FAIL; 556 goto out; 557 } 558 /* Prepare and append inner signature object */ 559 if ((r = sshbuf_put_bignum2_bytes(inner_sig, 560 resp->sig_r, resp->sig_r_len)) != 0 || 561 (r = sshbuf_put_bignum2_bytes(inner_sig, 562 resp->sig_s, resp->sig_s_len)) != 0) { 563 debug("%s: buffer error: %s", __func__, ssh_err(r)); 564 goto out; 565 } 566 if ((r = sshbuf_put_stringb(sig, inner_sig)) != 0 || 567 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 568 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 569 debug("%s: buffer error: %s", __func__, ssh_err(r)); 570 goto out; 571 } 572 #ifdef DEBUG_SK 573 fprintf(stderr, "%s: sig_r:\n", __func__); 574 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 575 fprintf(stderr, "%s: sig_s:\n", __func__); 576 sshbuf_dump_data(resp->sig_s, resp->sig_s_len, stderr); 577 fprintf(stderr, "%s: inner:\n", __func__); 578 sshbuf_dump(inner_sig, stderr); 579 #endif 580 r = 0; 581 out: 582 sshbuf_free(inner_sig); 583 return r; 584 } 585 #endif /* WITH_OPENSSL */ 586 587 static int 588 sshsk_ed25519_sig(struct sk_sign_response *resp, struct sshbuf *sig) 589 { 590 int r = SSH_ERR_INTERNAL_ERROR; 591 592 /* Check response validity */ 593 if (resp->sig_r == NULL) { 594 error("%s: sk_sign response invalid", __func__); 595 r = SSH_ERR_INVALID_FORMAT; 596 goto out; 597 } 598 if ((r = sshbuf_put_string(sig, 599 resp->sig_r, resp->sig_r_len)) != 0 || 600 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 601 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 602 debug("%s: buffer error: %s", __func__, ssh_err(r)); 603 goto out; 604 } 605 #ifdef DEBUG_SK 606 fprintf(stderr, "%s: sig_r:\n", __func__); 607 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 608 #endif 609 r = 0; 610 out: 611 return r; 612 } 613 614 int 615 sshsk_sign(const char *provider_path, struct sshkey *key, 616 u_char **sigp, size_t *lenp, const u_char *data, size_t datalen, 617 u_int compat, const char *pin) 618 { 619 struct sshsk_provider *skp = NULL; 620 int r = SSH_ERR_INTERNAL_ERROR; 621 int type, alg; 622 struct sk_sign_response *resp = NULL; 623 struct sshbuf *inner_sig = NULL, *sig = NULL; 624 struct sk_option **opts = NULL; 625 626 debug("%s: provider \"%s\", key %s, flags 0x%02x%s", __func__, 627 provider_path, sshkey_type(key), key->sk_flags, 628 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 629 630 if (sigp != NULL) 631 *sigp = NULL; 632 if (lenp != NULL) 633 *lenp = 0; 634 type = sshkey_type_plain(key->type); 635 switch (type) { 636 #ifdef WITH_OPENSSL 637 case KEY_ECDSA_SK: 638 alg = SSH_SK_ECDSA; 639 break; 640 #endif /* WITH_OPENSSL */ 641 case KEY_ED25519_SK: 642 alg = SSH_SK_ED25519; 643 break; 644 default: 645 return SSH_ERR_INVALID_ARGUMENT; 646 } 647 if (provider_path == NULL || 648 key->sk_key_handle == NULL || 649 key->sk_application == NULL || *key->sk_application == '\0') { 650 r = SSH_ERR_INVALID_ARGUMENT; 651 goto out; 652 } 653 if ((skp = sshsk_open(provider_path)) == NULL) { 654 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 655 goto out; 656 } 657 658 if ((r = skp->sk_sign(alg, data, datalen, key->sk_application, 659 sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle), 660 key->sk_flags, pin, opts, &resp)) != 0) { 661 debug("%s: sk_sign failed with code %d", __func__, r); 662 r = skerr_to_ssherr(r); 663 goto out; 664 } 665 /* Assemble signature */ 666 if ((sig = sshbuf_new()) == NULL) { 667 r = SSH_ERR_ALLOC_FAIL; 668 goto out; 669 } 670 if ((r = sshbuf_put_cstring(sig, sshkey_ssh_name_plain(key))) != 0) { 671 debug("%s: buffer error (outer): %s", __func__, ssh_err(r)); 672 goto out; 673 } 674 switch (type) { 675 #ifdef WITH_OPENSSL 676 case KEY_ECDSA_SK: 677 if ((r = sshsk_ecdsa_sig(resp, sig)) != 0) 678 goto out; 679 break; 680 #endif /* WITH_OPENSSL */ 681 case KEY_ED25519_SK: 682 if ((r = sshsk_ed25519_sig(resp, sig)) != 0) 683 goto out; 684 break; 685 } 686 #ifdef DEBUG_SK 687 fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n", 688 __func__, resp->flags, resp->counter); 689 fprintf(stderr, "%s: hashed message:\n", __func__); 690 sshbuf_dump_data(message, sizeof(message), stderr); 691 fprintf(stderr, "%s: sigbuf:\n", __func__); 692 sshbuf_dump(sig, stderr); 693 #endif 694 if (sigp != NULL) { 695 if ((*sigp = malloc(sshbuf_len(sig))) == NULL) { 696 r = SSH_ERR_ALLOC_FAIL; 697 goto out; 698 } 699 memcpy(*sigp, sshbuf_ptr(sig), sshbuf_len(sig)); 700 } 701 if (lenp != NULL) 702 *lenp = sshbuf_len(sig); 703 /* success */ 704 r = 0; 705 out: 706 sshsk_free_options(opts); 707 sshsk_free(skp); 708 sshsk_free_sign_response(resp); 709 sshbuf_free(sig); 710 sshbuf_free(inner_sig); 711 return r; 712 } 713 714 static void 715 sshsk_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 } 732 733 int 734 sshsk_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 flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY; 779 if ((rks[i]->flags & SSH_SK_USER_VERIFICATION_REQD)) 780 flags |= SSH_SK_USER_VERIFICATION_REQD; 781 if ((r = sshsk_key_from_response(rks[i]->alg, 782 rks[i]->application, flags, &rks[i]->key, &key)) != 0) 783 goto out; 784 if ((tmp = recallocarray(keys, nkeys, nkeys + 1, 785 sizeof(*tmp))) == NULL) { 786 error("%s: recallocarray failed", __func__); 787 r = SSH_ERR_ALLOC_FAIL; 788 goto out; 789 } 790 keys = tmp; 791 keys[nkeys++] = key; 792 key = NULL; 793 /* XXX synthesise comment */ 794 } 795 /* success */ 796 *keysp = keys; 797 *nkeysp = nkeys; 798 keys = NULL; 799 nkeys = 0; 800 r = 0; 801 out: 802 sshsk_free_options(opts); 803 sshsk_free(skp); 804 sshsk_free_sk_resident_keys(rks, nrks); 805 sshkey_free(key); 806 if (nkeys != 0) { 807 for (i = 0; i < nkeys; i++) 808 sshkey_free(keys[i]); 809 free(keys); 810 } 811 return r; 812 } 813 814
Indexes created Mon Mar 16 00:23:04 UTC 2026