ssh-sk.c revision 1.5
1 /* $NetBSD: ssh-sk.c,v 1.5 2021/03/05 17:47:16 christos Exp $ */ 2 /* $OpenBSD: ssh-sk.c,v 1.35 2021/02/26 00:16:58 djm Exp $ */ 3 4 /* 5 * Copyright (c) 2019 Google LLC 6 * 7 * Permission to use, copy, modify, and distribute this software for any 8 * purpose with or without fee is hereby granted, provided that the above 9 * copyright notice and this permission notice appear in all copies. 10 * 11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 18 */ 19 #include "includes.h" 20 __RCSID("$NetBSD: ssh-sk.c,v 1.5 2021/03/05 17:47:16 christos Exp $"); 21 22 /* #define DEBUG_SK 1 */ 23 24 #include <dlfcn.h> 25 #include <stddef.h> 26 #include <stdint.h> 27 #include <string.h> 28 #include <stdio.h> 29 30 #ifdef WITH_OPENSSL 31 #include <openssl/objects.h> 32 #include <openssl/ec.h> 33 #endif /* WITH_OPENSSL */ 34 35 #include "log.h" 36 #include "misc.h" 37 #include "sshbuf.h" 38 #include "sshkey.h" 39 #include "ssherr.h" 40 #include "digest.h" 41 42 #include "ssh-sk.h" 43 #include "sk-api.h" 44 #include "crypto_api.h" 45 46 struct sshsk_provider { 47 char *path; 48 void *dlhandle; 49 50 /* Return the version of the middleware API */ 51 uint32_t (*sk_api_version)(void); 52 53 /* Enroll a U2F key (private key generation) */ 54 int (*sk_enroll)(int alg, const uint8_t *challenge, 55 size_t challenge_len, const char *application, uint8_t flags, 56 const char *pin, struct sk_option **opts, 57 struct sk_enroll_response **enroll_response); 58 59 /* Sign a challenge */ 60 int (*sk_sign)(int alg, const uint8_t *message, size_t message_len, 61 const char *application, 62 const uint8_t *key_handle, size_t key_handle_len, 63 uint8_t flags, const char *pin, struct sk_option **opts, 64 struct sk_sign_response **sign_response); 65 66 /* Enumerate resident keys */ 67 int (*sk_load_resident_keys)(const char *pin, struct sk_option **opts, 68 struct sk_resident_key ***rks, size_t *nrks); 69 }; 70 71 /* Built-in version */ 72 int ssh_sk_enroll(int alg, const uint8_t *challenge, 73 size_t challenge_len, const char *application, uint8_t flags, 74 const char *pin, struct sk_option **opts, 75 struct sk_enroll_response **enroll_response); 76 int ssh_sk_sign(int alg, const uint8_t *message, size_t message_len, 77 const char *application, 78 const uint8_t *key_handle, size_t key_handle_len, 79 uint8_t flags, const char *pin, struct sk_option **opts, 80 struct sk_sign_response **sign_response); 81 int ssh_sk_load_resident_keys(const char *pin, struct sk_option **opts, 82 struct sk_resident_key ***rks, size_t *nrks); 83 84 static void 85 sshsk_free(struct sshsk_provider *p) 86 { 87 if (p == NULL) 88 return; 89 free(p->path); 90 if (p->dlhandle != NULL) 91 dlclose(p->dlhandle); 92 free(p); 93 } 94 95 static struct sshsk_provider * 96 sshsk_open(const char *path) 97 { 98 struct sshsk_provider *ret = NULL; 99 uint32_t version; 100 101 if (path == NULL || *path == '\0') { 102 error("No FIDO SecurityKeyProvider specified"); 103 return NULL; 104 } 105 if ((ret = calloc(1, sizeof(*ret))) == NULL) { 106 error_f("calloc failed"); 107 return NULL; 108 } 109 if ((ret->path = strdup(path)) == NULL) { 110 error_f("strdup failed"); 111 goto fail; 112 } 113 /* Skip the rest if we're using the linked in middleware */ 114 if (strcasecmp(ret->path, "internal") == 0) { 115 ret->sk_enroll = ssh_sk_enroll; 116 ret->sk_sign = ssh_sk_sign; 117 ret->sk_load_resident_keys = ssh_sk_load_resident_keys; 118 return ret; 119 } 120 if ((ret->dlhandle = dlopen(path, RTLD_NOW)) == NULL) { 121 error("Provider \"%s\" dlopen failed: %s", path, dlerror()); 122 goto fail; 123 } 124 if ((ret->sk_api_version = dlsym(ret->dlhandle, 125 "sk_api_version")) == NULL) { 126 error("Provider \"%s\" dlsym(sk_api_version) failed: %s", 127 path, dlerror()); 128 goto fail; 129 } 130 version = ret->sk_api_version(); 131 debug_f("provider %s implements version 0x%08lx", ret->path, 132 (u_long)version); 133 if ((version & SSH_SK_VERSION_MAJOR_MASK) != SSH_SK_VERSION_MAJOR) { 134 error("Provider \"%s\" implements unsupported " 135 "version 0x%08lx (supported: 0x%08lx)", 136 path, (u_long)version, (u_long)SSH_SK_VERSION_MAJOR); 137 goto fail; 138 } 139 if ((ret->sk_enroll = dlsym(ret->dlhandle, "sk_enroll")) == NULL) { 140 error("Provider %s dlsym(sk_enroll) failed: %s", 141 path, dlerror()); 142 goto fail; 143 } 144 if ((ret->sk_sign = dlsym(ret->dlhandle, "sk_sign")) == NULL) { 145 error("Provider \"%s\" dlsym(sk_sign) failed: %s", 146 path, dlerror()); 147 goto fail; 148 } 149 if ((ret->sk_load_resident_keys = dlsym(ret->dlhandle, 150 "sk_load_resident_keys")) == NULL) { 151 error("Provider \"%s\" dlsym(sk_load_resident_keys) " 152 "failed: %s", path, dlerror()); 153 goto fail; 154 } 155 /* success */ 156 return ret; 157 fail: 158 sshsk_free(ret); 159 return NULL; 160 } 161 162 static void 163 sshsk_free_enroll_response(struct sk_enroll_response *r) 164 { 165 if (r == NULL) 166 return; 167 freezero(r->key_handle, r->key_handle_len); 168 freezero(r->public_key, r->public_key_len); 169 freezero(r->signature, r->signature_len); 170 freezero(r->attestation_cert, r->attestation_cert_len); 171 freezero(r->authdata, r->authdata_len); 172 freezero(r, sizeof(*r)); 173 } 174 175 static void 176 sshsk_free_sign_response(struct sk_sign_response *r) 177 { 178 if (r == NULL) 179 return; 180 freezero(r->sig_r, r->sig_r_len); 181 freezero(r->sig_s, r->sig_s_len); 182 freezero(r, sizeof(*r)); 183 } 184 185 #ifdef WITH_OPENSSL 186 /* Assemble key from response */ 187 static int 188 sshsk_ecdsa_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 189 { 190 struct sshkey *key = NULL; 191 struct sshbuf *b = NULL; 192 EC_POINT *q = NULL; 193 int r; 194 195 *keyp = NULL; 196 if ((key = sshkey_new(KEY_ECDSA_SK)) == NULL) { 197 error_f("sshkey_new failed"); 198 r = SSH_ERR_ALLOC_FAIL; 199 goto out; 200 } 201 key->ecdsa_nid = NID_X9_62_prime256v1; 202 if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL || 203 (q = EC_POINT_new(EC_KEY_get0_group(key->ecdsa))) == NULL || 204 (b = sshbuf_new()) == NULL) { 205 error_f("allocation failed"); 206 r = SSH_ERR_ALLOC_FAIL; 207 goto out; 208 } 209 if ((r = sshbuf_put_string(b, 210 resp->public_key, resp->public_key_len)) != 0) { 211 error_fr(r, "sshbuf_put_string"); 212 goto out; 213 } 214 if ((r = sshbuf_get_ec(b, q, EC_KEY_get0_group(key->ecdsa))) != 0) { 215 error_fr(r, "parse"); 216 r = SSH_ERR_INVALID_FORMAT; 217 goto out; 218 } 219 if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa), q) != 0) { 220 error("Authenticator returned invalid ECDSA key"); 221 r = SSH_ERR_KEY_INVALID_EC_VALUE; 222 goto out; 223 } 224 if (EC_KEY_set_public_key(key->ecdsa, q) != 1) { 225 /* XXX assume it is a allocation error */ 226 error_f("allocation failed"); 227 r = SSH_ERR_ALLOC_FAIL; 228 goto out; 229 } 230 /* success */ 231 *keyp = key; 232 key = NULL; /* transferred */ 233 r = 0; 234 out: 235 EC_POINT_free(q); 236 sshkey_free(key); 237 sshbuf_free(b); 238 return r; 239 } 240 #endif /* WITH_OPENSSL */ 241 242 static int 243 sshsk_ed25519_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 244 { 245 struct sshkey *key = NULL; 246 int r; 247 248 *keyp = NULL; 249 if (resp->public_key_len != ED25519_PK_SZ) { 250 error_f("invalid size: %zu", resp->public_key_len); 251 r = SSH_ERR_INVALID_FORMAT; 252 goto out; 253 } 254 if ((key = sshkey_new(KEY_ED25519_SK)) == NULL) { 255 error_f("sshkey_new failed"); 256 r = SSH_ERR_ALLOC_FAIL; 257 goto out; 258 } 259 if ((key->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) { 260 error_f("malloc failed"); 261 r = SSH_ERR_ALLOC_FAIL; 262 goto out; 263 } 264 memcpy(key->ed25519_pk, resp->public_key, ED25519_PK_SZ); 265 /* success */ 266 *keyp = key; 267 key = NULL; /* transferred */ 268 r = 0; 269 out: 270 sshkey_free(key); 271 return r; 272 } 273 274 static int 275 sshsk_key_from_response(int alg, const char *application, uint8_t flags, 276 struct sk_enroll_response *resp, struct sshkey **keyp) 277 { 278 struct sshkey *key = NULL; 279 int r = SSH_ERR_INTERNAL_ERROR; 280 281 *keyp = NULL; 282 283 /* Check response validity */ 284 if (resp->public_key == NULL || resp->key_handle == NULL) { 285 error_f("sk_enroll response invalid"); 286 r = SSH_ERR_INVALID_FORMAT; 287 goto out; 288 } 289 switch (alg) { 290 #ifdef WITH_OPENSSL 291 case SSH_SK_ECDSA: 292 if ((r = sshsk_ecdsa_assemble(resp, &key)) != 0) 293 goto out; 294 break; 295 #endif /* WITH_OPENSSL */ 296 case SSH_SK_ED25519: 297 if ((r = sshsk_ed25519_assemble(resp, &key)) != 0) 298 goto out; 299 break; 300 default: 301 error_f("unsupported algorithm %d", alg); 302 r = SSH_ERR_INVALID_ARGUMENT; 303 goto out; 304 } 305 key->sk_flags = flags; 306 if ((key->sk_key_handle = sshbuf_new()) == NULL || 307 (key->sk_reserved = sshbuf_new()) == NULL) { 308 error_f("allocation failed"); 309 r = SSH_ERR_ALLOC_FAIL; 310 goto out; 311 } 312 if ((key->sk_application = strdup(application)) == NULL) { 313 error_f("strdup application failed"); 314 r = SSH_ERR_ALLOC_FAIL; 315 goto out; 316 } 317 if ((r = sshbuf_put(key->sk_key_handle, resp->key_handle, 318 resp->key_handle_len)) != 0) { 319 error_fr(r, "put key handle"); 320 goto out; 321 } 322 /* success */ 323 r = 0; 324 *keyp = key; 325 key = NULL; 326 out: 327 sshkey_free(key); 328 return r; 329 } 330 331 static int 332 skerr_to_ssherr(int skerr) 333 { 334 switch (skerr) { 335 case SSH_SK_ERR_UNSUPPORTED: 336 return SSH_ERR_FEATURE_UNSUPPORTED; 337 case SSH_SK_ERR_PIN_REQUIRED: 338 return SSH_ERR_KEY_WRONG_PASSPHRASE; 339 case SSH_SK_ERR_DEVICE_NOT_FOUND: 340 return SSH_ERR_DEVICE_NOT_FOUND; 341 case SSH_SK_ERR_GENERAL: 342 default: 343 return SSH_ERR_INVALID_FORMAT; 344 } 345 } 346 347 static void 348 sshsk_free_options(struct sk_option **opts) 349 { 350 size_t i; 351 352 if (opts == NULL) 353 return; 354 for (i = 0; opts[i] != NULL; i++) { 355 free(opts[i]->name); 356 free(opts[i]->value); 357 free(opts[i]); 358 } 359 free(opts); 360 } 361 362 static int 363 sshsk_add_option(struct sk_option ***optsp, size_t *noptsp, 364 const char *name, const char *value, uint8_t required) 365 { 366 struct sk_option **opts = *optsp; 367 size_t nopts = *noptsp; 368 369 if ((opts = recallocarray(opts, nopts, nopts + 2, /* extra for NULL */ 370 sizeof(*opts))) == NULL) { 371 error_f("array alloc failed"); 372 return SSH_ERR_ALLOC_FAIL; 373 } 374 *optsp = opts; 375 *noptsp = nopts + 1; 376 if ((opts[nopts] = calloc(1, sizeof(**opts))) == NULL) { 377 error_f("alloc failed"); 378 return SSH_ERR_ALLOC_FAIL; 379 } 380 if ((opts[nopts]->name = strdup(name)) == NULL || 381 (opts[nopts]->value = strdup(value)) == NULL) { 382 error_f("alloc failed"); 383 return SSH_ERR_ALLOC_FAIL; 384 } 385 opts[nopts]->required = required; 386 return 0; 387 } 388 389 static int 390 make_options(const char *device, const char *user_id, 391 struct sk_option ***optsp) 392 { 393 struct sk_option **opts = NULL; 394 size_t nopts = 0; 395 int r, ret = SSH_ERR_INTERNAL_ERROR; 396 397 if (device != NULL && 398 (r = sshsk_add_option(&opts, &nopts, "device", device, 0)) != 0) { 399 ret = r; 400 goto out; 401 } 402 if (user_id != NULL && 403 (r = sshsk_add_option(&opts, &nopts, "user", user_id, 0)) != 0) { 404 ret = r; 405 goto out; 406 } 407 /* success */ 408 *optsp = opts; 409 opts = NULL; 410 nopts = 0; 411 ret = 0; 412 out: 413 sshsk_free_options(opts); 414 return ret; 415 } 416 417 418 static int 419 fill_attestation_blob(const struct sk_enroll_response *resp, 420 struct sshbuf *attest) 421 { 422 int r; 423 424 if (attest == NULL) 425 return 0; /* nothing to do */ 426 if ((r = sshbuf_put_cstring(attest, "ssh-sk-attest-v01")) != 0 || 427 (r = sshbuf_put_string(attest, 428 resp->attestation_cert, resp->attestation_cert_len)) != 0 || 429 (r = sshbuf_put_string(attest, 430 resp->signature, resp->signature_len)) != 0 || 431 (r = sshbuf_put_string(attest, 432 resp->authdata, resp->authdata_len)) != 0 || 433 (r = sshbuf_put_u32(attest, 0)) != 0 || /* resvd flags */ 434 (r = sshbuf_put_string(attest, NULL, 0)) != 0 /* resvd */) { 435 error_fr(r, "compose"); 436 return r; 437 } 438 /* success */ 439 return 0; 440 } 441 442 int 443 sshsk_enroll(int type, const char *provider_path, const char *device, 444 const char *application, const char *userid, uint8_t flags, 445 const char *pin, struct sshbuf *challenge_buf, 446 struct sshkey **keyp, struct sshbuf *attest) 447 { 448 struct sshsk_provider *skp = NULL; 449 struct sshkey *key = NULL; 450 u_char randchall[32]; 451 const u_char *challenge; 452 size_t challenge_len; 453 struct sk_enroll_response *resp = NULL; 454 struct sk_option **opts = NULL; 455 int r = SSH_ERR_INTERNAL_ERROR; 456 int alg; 457 458 debug_f("provider \"%s\", device \"%s\", application \"%s\", " 459 "userid \"%s\", flags 0x%02x, challenge len %zu%s", 460 provider_path, device, application, userid, flags, 461 challenge_buf == NULL ? 0 : sshbuf_len(challenge_buf), 462 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 463 464 *keyp = NULL; 465 if (attest) 466 sshbuf_reset(attest); 467 468 if ((r = make_options(device, userid, &opts)) != 0) 469 goto out; 470 471 switch (type) { 472 #ifdef WITH_OPENSSL 473 case KEY_ECDSA_SK: 474 alg = SSH_SK_ECDSA; 475 break; 476 #endif /* WITH_OPENSSL */ 477 case KEY_ED25519_SK: 478 alg = SSH_SK_ED25519; 479 break; 480 default: 481 error_f("unsupported key type"); 482 r = SSH_ERR_INVALID_ARGUMENT; 483 goto out; 484 } 485 if (provider_path == NULL) { 486 error_f("missing provider"); 487 r = SSH_ERR_INVALID_ARGUMENT; 488 goto out; 489 } 490 if (application == NULL || *application == '\0') { 491 error_f("missing application"); 492 r = SSH_ERR_INVALID_ARGUMENT; 493 goto out; 494 } 495 if (challenge_buf == NULL) { 496 debug_f("using random challenge"); 497 arc4random_buf(randchall, sizeof(randchall)); 498 challenge = randchall; 499 challenge_len = sizeof(randchall); 500 } else if (sshbuf_len(challenge_buf) == 0) { 501 error("Missing enrollment challenge"); 502 r = SSH_ERR_INVALID_ARGUMENT; 503 goto out; 504 } else { 505 challenge = sshbuf_ptr(challenge_buf); 506 challenge_len = sshbuf_len(challenge_buf); 507 debug3_f("using explicit challenge len=%zd", challenge_len); 508 } 509 if ((skp = sshsk_open(provider_path)) == NULL) { 510 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 511 goto out; 512 } 513 /* XXX validate flags? */ 514 /* enroll key */ 515 if ((r = skp->sk_enroll(alg, challenge, challenge_len, application, 516 flags, pin, opts, &resp)) != 0) { 517 debug_f("provider \"%s\" failure %d", provider_path, r); 518 r = skerr_to_ssherr(r); 519 goto out; 520 } 521 522 if ((r = sshsk_key_from_response(alg, application, flags, 523 resp, &key)) != 0) 524 goto out; 525 526 /* Optionally fill in the attestation information */ 527 if ((r = fill_attestation_blob(resp, attest)) != 0) 528 goto out; 529 530 /* success */ 531 *keyp = key; 532 key = NULL; /* transferred */ 533 r = 0; 534 out: 535 sshsk_free_options(opts); 536 sshsk_free(skp); 537 sshkey_free(key); 538 sshsk_free_enroll_response(resp); 539 explicit_bzero(randchall, sizeof(randchall)); 540 return r; 541 } 542 543 #ifdef WITH_OPENSSL 544 static int 545 sshsk_ecdsa_sig(struct sk_sign_response *resp, struct sshbuf *sig) 546 { 547 struct sshbuf *inner_sig = NULL; 548 int r = SSH_ERR_INTERNAL_ERROR; 549 550 /* Check response validity */ 551 if (resp->sig_r == NULL || resp->sig_s == NULL) { 552 error_f("sk_sign response invalid"); 553 r = SSH_ERR_INVALID_FORMAT; 554 goto out; 555 } 556 if ((inner_sig = sshbuf_new()) == NULL) { 557 r = SSH_ERR_ALLOC_FAIL; 558 goto out; 559 } 560 /* Prepare and append inner signature object */ 561 if ((r = sshbuf_put_bignum2_bytes(inner_sig, 562 resp->sig_r, resp->sig_r_len)) != 0 || 563 (r = sshbuf_put_bignum2_bytes(inner_sig, 564 resp->sig_s, resp->sig_s_len)) != 0) { 565 error_fr(r, "compose inner"); 566 goto out; 567 } 568 if ((r = sshbuf_put_stringb(sig, inner_sig)) != 0 || 569 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 570 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 571 error_fr(r, "compose"); 572 goto out; 573 } 574 #ifdef DEBUG_SK 575 fprintf(stderr, "%s: sig_r:\n", __func__); 576 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 577 fprintf(stderr, "%s: sig_s:\n", __func__); 578 sshbuf_dump_data(resp->sig_s, resp->sig_s_len, stderr); 579 fprintf(stderr, "%s: inner:\n", __func__); 580 sshbuf_dump(inner_sig, stderr); 581 #endif 582 r = 0; 583 out: 584 sshbuf_free(inner_sig); 585 return r; 586 } 587 #endif /* WITH_OPENSSL */ 588 589 static int 590 sshsk_ed25519_sig(struct sk_sign_response *resp, struct sshbuf *sig) 591 { 592 int r = SSH_ERR_INTERNAL_ERROR; 593 594 /* Check response validity */ 595 if (resp->sig_r == NULL) { 596 error_f("sk_sign response invalid"); 597 r = SSH_ERR_INVALID_FORMAT; 598 goto out; 599 } 600 if ((r = sshbuf_put_string(sig, 601 resp->sig_r, resp->sig_r_len)) != 0 || 602 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 603 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 604 error_fr(r, "compose"); 605 goto out; 606 } 607 #ifdef DEBUG_SK 608 fprintf(stderr, "%s: sig_r:\n", __func__); 609 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 610 #endif 611 r = 0; 612 out: 613 return r; 614 } 615 616 int 617 sshsk_sign(const char *provider_path, struct sshkey *key, 618 u_char **sigp, size_t *lenp, const u_char *data, size_t datalen, 619 u_int compat, const char *pin) 620 { 621 struct sshsk_provider *skp = NULL; 622 int r = SSH_ERR_INTERNAL_ERROR; 623 int type, alg; 624 struct sk_sign_response *resp = NULL; 625 struct sshbuf *inner_sig = NULL, *sig = NULL; 626 struct sk_option **opts = NULL; 627 628 debug_f("provider \"%s\", key %s, flags 0x%02x%s", 629 provider_path, sshkey_type(key), key->sk_flags, 630 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 631 632 if (sigp != NULL) 633 *sigp = NULL; 634 if (lenp != NULL) 635 *lenp = 0; 636 type = sshkey_type_plain(key->type); 637 switch (type) { 638 #ifdef WITH_OPENSSL 639 case KEY_ECDSA_SK: 640 alg = SSH_SK_ECDSA; 641 break; 642 #endif /* WITH_OPENSSL */ 643 case KEY_ED25519_SK: 644 alg = SSH_SK_ED25519; 645 break; 646 default: 647 return SSH_ERR_INVALID_ARGUMENT; 648 } 649 if (provider_path == NULL || 650 key->sk_key_handle == NULL || 651 key->sk_application == NULL || *key->sk_application == '\0') { 652 r = SSH_ERR_INVALID_ARGUMENT; 653 goto out; 654 } 655 if ((skp = sshsk_open(provider_path)) == NULL) { 656 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 657 goto out; 658 } 659 #ifdef DEBUG_SK 660 fprintf(stderr, "%s: sk_flags = 0x%02x, sk_application = \"%s\"\n", 661 __func__, key->sk_flags, key->sk_application); 662 fprintf(stderr, "%s: sk_key_handle:\n", __func__); 663 sshbuf_dump(key->sk_key_handle, stderr); 664 #endif 665 if ((r = skp->sk_sign(alg, data, datalen, key->sk_application, 666 sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle), 667 key->sk_flags, pin, opts, &resp)) != 0) { 668 debug_f("sk_sign failed with code %d", r); 669 r = skerr_to_ssherr(r); 670 goto out; 671 } 672 /* Assemble signature */ 673 if ((sig = sshbuf_new()) == NULL) { 674 r = SSH_ERR_ALLOC_FAIL; 675 goto out; 676 } 677 if ((r = sshbuf_put_cstring(sig, sshkey_ssh_name_plain(key))) != 0) { 678 error_fr(r, "compose outer"); 679 goto out; 680 } 681 switch (type) { 682 #ifdef WITH_OPENSSL 683 case KEY_ECDSA_SK: 684 if ((r = sshsk_ecdsa_sig(resp, sig)) != 0) 685 goto out; 686 break; 687 #endif /* WITH_OPENSSL */ 688 case KEY_ED25519_SK: 689 if ((r = sshsk_ed25519_sig(resp, sig)) != 0) 690 goto out; 691 break; 692 } 693 #ifdef DEBUG_SK 694 fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n", 695 __func__, resp->flags, resp->counter); 696 fprintf(stderr, "%s: data to sign:\n", __func__); 697 sshbuf_dump_data(data, datalen, stderr); 698 fprintf(stderr, "%s: sigbuf:\n", __func__); 699 sshbuf_dump(sig, stderr); 700 #endif 701 if (sigp != NULL) { 702 if ((*sigp = malloc(sshbuf_len(sig))) == NULL) { 703 r = SSH_ERR_ALLOC_FAIL; 704 goto out; 705 } 706 memcpy(*sigp, sshbuf_ptr(sig), sshbuf_len(sig)); 707 } 708 if (lenp != NULL) 709 *lenp = sshbuf_len(sig); 710 /* success */ 711 r = 0; 712 out: 713 sshsk_free_options(opts); 714 sshsk_free(skp); 715 sshsk_free_sign_response(resp); 716 sshbuf_free(sig); 717 sshbuf_free(inner_sig); 718 return r; 719 } 720 721 static void 722 sshsk_free_sk_resident_keys(struct sk_resident_key **rks, size_t nrks) 723 { 724 size_t i; 725 726 if (nrks == 0 || rks == NULL) 727 return; 728 for (i = 0; i < nrks; i++) { 729 free(rks[i]->application); 730 freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len); 731 freezero(rks[i]->key.public_key, rks[i]->key.public_key_len); 732 freezero(rks[i]->key.signature, rks[i]->key.signature_len); 733 freezero(rks[i]->key.attestation_cert, 734 rks[i]->key.attestation_cert_len); 735 freezero(rks[i], sizeof(**rks)); 736 } 737 free(rks); 738 } 739 740 int 741 sshsk_load_resident(const char *provider_path, const char *device, 742 const char *pin, struct sshkey ***keysp, size_t *nkeysp) 743 { 744 struct sshsk_provider *skp = NULL; 745 int r = SSH_ERR_INTERNAL_ERROR; 746 struct sk_resident_key **rks = NULL; 747 size_t i, nrks = 0, nkeys = 0; 748 struct sshkey *key = NULL, **keys = NULL, **tmp; 749 uint8_t flags; 750 struct sk_option **opts = NULL; 751 752 debug_f("provider \"%s\"%s", provider_path, 753 (pin != NULL && *pin != '\0') ? ", have-pin": ""); 754 755 if (keysp == NULL || nkeysp == NULL) 756 return SSH_ERR_INVALID_ARGUMENT; 757 *keysp = NULL; 758 *nkeysp = 0; 759 760 if ((r = make_options(device, NULL, &opts)) != 0) 761 goto out; 762 if ((skp = sshsk_open(provider_path)) == NULL) { 763 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 764 goto out; 765 } 766 if ((r = skp->sk_load_resident_keys(pin, opts, &rks, &nrks)) != 0) { 767 error("Provider \"%s\" returned failure %d", provider_path, r); 768 r = skerr_to_ssherr(r); 769 goto out; 770 } 771 for (i = 0; i < nrks; i++) { 772 debug3_f("rk %zu: slot = %zu, alg = %d, application = \"%s\"", 773 i, rks[i]->slot, rks[i]->alg, rks[i]->application); 774 /* XXX need better filter here */ 775 if (strncmp(rks[i]->application, "ssh:", 4) != 0) 776 continue; 777 switch (rks[i]->alg) { 778 case SSH_SK_ECDSA: 779 case SSH_SK_ED25519: 780 break; 781 default: 782 continue; 783 } 784 flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY; 785 if ((rks[i]->flags & SSH_SK_USER_VERIFICATION_REQD)) 786 flags |= SSH_SK_USER_VERIFICATION_REQD; 787 if ((r = sshsk_key_from_response(rks[i]->alg, 788 rks[i]->application, flags, &rks[i]->key, &key)) != 0) 789 goto out; 790 if ((tmp = recallocarray(keys, nkeys, nkeys + 1, 791 sizeof(*tmp))) == NULL) { 792 error_f("recallocarray failed"); 793 r = SSH_ERR_ALLOC_FAIL; 794 goto out; 795 } 796 keys = tmp; 797 keys[nkeys++] = key; 798 key = NULL; 799 /* XXX synthesise comment */ 800 } 801 /* success */ 802 *keysp = keys; 803 *nkeysp = nkeys; 804 keys = NULL; 805 nkeys = 0; 806 r = 0; 807 out: 808 sshsk_free_options(opts); 809 sshsk_free(skp); 810 sshsk_free_sk_resident_keys(rks, nrks); 811 sshkey_free(key); 812 if (nkeys != 0) { 813 for (i = 0; i < nkeys; i++) 814 sshkey_free(keys[i]); 815 free(keys); 816 } 817 return r; 818 } 819 820
Indexes created Mon Mar 16 00:23:04 UTC 2026