ssh-sk.c revision 1.4
1 /* $NetBSD: ssh-sk.c,v 1.4 2020/12/04 18:42:50 christos Exp $ */ 2 /* $OpenBSD: ssh-sk.c,v 1.32 2020/09/09 03:08:02 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 1.4 2020/12/04 18:42:50 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("%s: calloc failed", __func__); 107 return NULL; 108 } 109 if ((ret->path = strdup(path)) == NULL) { 110 error("%s: strdup failed", __func__); 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("%s: provider %s implements version 0x%08lx", __func__, 132 ret->path, (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("%s: sshkey_new failed", __func__); 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("%s: allocation failed", __func__); 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("%s: buffer error: %s", __func__, ssh_err(r)); 212 goto out; 213 } 214 if ((r = sshbuf_get_ec(b, q, EC_KEY_get0_group(key->ecdsa))) != 0) { 215 error("%s: parse key: %s", __func__, ssh_err(r)); 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("%s: allocation failed", __func__); 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("%s: invalid size: %zu", __func__, 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("%s: sshkey_new failed", __func__); 256 r = SSH_ERR_ALLOC_FAIL; 257 goto out; 258 } 259 if ((key->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) { 260 error("%s: malloc failed", __func__); 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("%s: sk_enroll response invalid", __func__); 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("%s: unsupported algorithm %d", __func__, 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("%s: allocation failed", __func__); 309 r = SSH_ERR_ALLOC_FAIL; 310 goto out; 311 } 312 if ((key->sk_application = strdup(application)) == NULL) { 313 error("%s: strdup application failed", __func__); 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("%s: buffer error: %s", __func__, ssh_err(r)); 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("%s: array alloc failed", __func__); 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("%s: alloc failed", __func__); 378 return SSH_ERR_ALLOC_FAIL; 379 } 380 if ((opts[nopts]->name = strdup(name)) == NULL || 381 (opts[nopts]->value = strdup(value)) == NULL) { 382 error("%s: alloc failed", __func__); 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("%s: buffer error: %s", __func__, ssh_err(r)); 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("%s: provider \"%s\", device \"%s\", application \"%s\", " 459 "userid \"%s\", flags 0x%02x, challenge len %zu%s", __func__, 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("%s: unsupported key type", __func__); 482 r = SSH_ERR_INVALID_ARGUMENT; 483 goto out; 484 } 485 if (provider_path == NULL) { 486 error("%s: missing provider", __func__); 487 r = SSH_ERR_INVALID_ARGUMENT; 488 goto out; 489 } 490 if (application == NULL || *application == '\0') { 491 error("%s: missing application", __func__); 492 r = SSH_ERR_INVALID_ARGUMENT; 493 goto out; 494 } 495 if (challenge_buf == NULL) { 496 debug("%s: using random challenge", __func__); 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("%s: using explicit challenge len=%zd", 508 __func__, challenge_len); 509 } 510 if ((skp = sshsk_open(provider_path)) == NULL) { 511 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 512 goto out; 513 } 514 /* XXX validate flags? */ 515 /* enroll key */ 516 if ((r = skp->sk_enroll(alg, challenge, challenge_len, application, 517 flags, pin, opts, &resp)) != 0) { 518 debug("%s: provider \"%s\" returned failure %d", __func__, 519 provider_path, r); 520 r = skerr_to_ssherr(r); 521 goto out; 522 } 523 524 if ((r = sshsk_key_from_response(alg, application, flags, 525 resp, &key)) != 0) 526 goto out; 527 528 /* Optionally fill in the attestation information */ 529 if ((r = fill_attestation_blob(resp, attest)) != 0) 530 goto out; 531 532 /* success */ 533 *keyp = key; 534 key = NULL; /* transferred */ 535 r = 0; 536 out: 537 sshsk_free_options(opts); 538 sshsk_free(skp); 539 sshkey_free(key); 540 sshsk_free_enroll_response(resp); 541 explicit_bzero(randchall, sizeof(randchall)); 542 return r; 543 } 544 545 #ifdef WITH_OPENSSL 546 static int 547 sshsk_ecdsa_sig(struct sk_sign_response *resp, struct sshbuf *sig) 548 { 549 struct sshbuf *inner_sig = NULL; 550 int r = SSH_ERR_INTERNAL_ERROR; 551 552 /* Check response validity */ 553 if (resp->sig_r == NULL || resp->sig_s == NULL) { 554 error("%s: sk_sign response invalid", __func__); 555 r = SSH_ERR_INVALID_FORMAT; 556 goto out; 557 } 558 if ((inner_sig = sshbuf_new()) == NULL) { 559 r = SSH_ERR_ALLOC_FAIL; 560 goto out; 561 } 562 /* Prepare and append inner signature object */ 563 if ((r = sshbuf_put_bignum2_bytes(inner_sig, 564 resp->sig_r, resp->sig_r_len)) != 0 || 565 (r = sshbuf_put_bignum2_bytes(inner_sig, 566 resp->sig_s, resp->sig_s_len)) != 0) { 567 debug("%s: buffer error: %s", __func__, ssh_err(r)); 568 goto out; 569 } 570 if ((r = sshbuf_put_stringb(sig, inner_sig)) != 0 || 571 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 572 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 573 debug("%s: buffer error: %s", __func__, ssh_err(r)); 574 goto out; 575 } 576 #ifdef DEBUG_SK 577 fprintf(stderr, "%s: sig_r:\n", __func__); 578 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 579 fprintf(stderr, "%s: sig_s:\n", __func__); 580 sshbuf_dump_data(resp->sig_s, resp->sig_s_len, stderr); 581 fprintf(stderr, "%s: inner:\n", __func__); 582 sshbuf_dump(inner_sig, stderr); 583 #endif 584 r = 0; 585 out: 586 sshbuf_free(inner_sig); 587 return r; 588 } 589 #endif /* WITH_OPENSSL */ 590 591 static int 592 sshsk_ed25519_sig(struct sk_sign_response *resp, struct sshbuf *sig) 593 { 594 int r = SSH_ERR_INTERNAL_ERROR; 595 596 /* Check response validity */ 597 if (resp->sig_r == NULL) { 598 error("%s: sk_sign response invalid", __func__); 599 r = SSH_ERR_INVALID_FORMAT; 600 goto out; 601 } 602 if ((r = sshbuf_put_string(sig, 603 resp->sig_r, resp->sig_r_len)) != 0 || 604 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 605 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 606 debug("%s: buffer error: %s", __func__, ssh_err(r)); 607 goto out; 608 } 609 #ifdef DEBUG_SK 610 fprintf(stderr, "%s: sig_r:\n", __func__); 611 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 612 #endif 613 r = 0; 614 out: 615 return r; 616 } 617 618 int 619 sshsk_sign(const char *provider_path, struct sshkey *key, 620 u_char **sigp, size_t *lenp, const u_char *data, size_t datalen, 621 u_int compat, const char *pin) 622 { 623 struct sshsk_provider *skp = NULL; 624 int r = SSH_ERR_INTERNAL_ERROR; 625 int type, alg; 626 struct sk_sign_response *resp = NULL; 627 struct sshbuf *inner_sig = NULL, *sig = NULL; 628 struct sk_option **opts = NULL; 629 630 debug("%s: provider \"%s\", key %s, flags 0x%02x%s", __func__, 631 provider_path, sshkey_type(key), key->sk_flags, 632 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 633 634 if (sigp != NULL) 635 *sigp = NULL; 636 if (lenp != NULL) 637 *lenp = 0; 638 type = sshkey_type_plain(key->type); 639 switch (type) { 640 #ifdef WITH_OPENSSL 641 case KEY_ECDSA_SK: 642 alg = SSH_SK_ECDSA; 643 break; 644 #endif /* WITH_OPENSSL */ 645 case KEY_ED25519_SK: 646 alg = SSH_SK_ED25519; 647 break; 648 default: 649 return SSH_ERR_INVALID_ARGUMENT; 650 } 651 if (provider_path == NULL || 652 key->sk_key_handle == NULL || 653 key->sk_application == NULL || *key->sk_application == '\0') { 654 r = SSH_ERR_INVALID_ARGUMENT; 655 goto out; 656 } 657 if ((skp = sshsk_open(provider_path)) == NULL) { 658 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 659 goto out; 660 } 661 662 if ((r = skp->sk_sign(alg, data, datalen, key->sk_application, 663 sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle), 664 key->sk_flags, pin, opts, &resp)) != 0) { 665 debug("%s: sk_sign failed with code %d", __func__, r); 666 r = skerr_to_ssherr(r); 667 goto out; 668 } 669 /* Assemble signature */ 670 if ((sig = sshbuf_new()) == NULL) { 671 r = SSH_ERR_ALLOC_FAIL; 672 goto out; 673 } 674 if ((r = sshbuf_put_cstring(sig, sshkey_ssh_name_plain(key))) != 0) { 675 debug("%s: buffer error (outer): %s", __func__, ssh_err(r)); 676 goto out; 677 } 678 switch (type) { 679 #ifdef WITH_OPENSSL 680 case KEY_ECDSA_SK: 681 if ((r = sshsk_ecdsa_sig(resp, sig)) != 0) 682 goto out; 683 break; 684 #endif /* WITH_OPENSSL */ 685 case KEY_ED25519_SK: 686 if ((r = sshsk_ed25519_sig(resp, sig)) != 0) 687 goto out; 688 break; 689 } 690 #ifdef DEBUG_SK 691 fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n", 692 __func__, resp->flags, resp->counter); 693 fprintf(stderr, "%s: hashed message:\n", __func__); 694 sshbuf_dump_data(message, sizeof(message), stderr); 695 fprintf(stderr, "%s: sigbuf:\n", __func__); 696 sshbuf_dump(sig, stderr); 697 #endif 698 if (sigp != NULL) { 699 if ((*sigp = malloc(sshbuf_len(sig))) == NULL) { 700 r = SSH_ERR_ALLOC_FAIL; 701 goto out; 702 } 703 memcpy(*sigp, sshbuf_ptr(sig), sshbuf_len(sig)); 704 } 705 if (lenp != NULL) 706 *lenp = sshbuf_len(sig); 707 /* success */ 708 r = 0; 709 out: 710 sshsk_free_options(opts); 711 sshsk_free(skp); 712 sshsk_free_sign_response(resp); 713 sshbuf_free(sig); 714 sshbuf_free(inner_sig); 715 return r; 716 } 717 718 static void 719 sshsk_free_sk_resident_keys(struct sk_resident_key **rks, size_t nrks) 720 { 721 size_t i; 722 723 if (nrks == 0 || rks == NULL) 724 return; 725 for (i = 0; i < nrks; i++) { 726 free(rks[i]->application); 727 freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len); 728 freezero(rks[i]->key.public_key, rks[i]->key.public_key_len); 729 freezero(rks[i]->key.signature, rks[i]->key.signature_len); 730 freezero(rks[i]->key.attestation_cert, 731 rks[i]->key.attestation_cert_len); 732 freezero(rks[i], sizeof(**rks)); 733 } 734 free(rks); 735 } 736 737 int 738 sshsk_load_resident(const char *provider_path, const char *device, 739 const char *pin, struct sshkey ***keysp, size_t *nkeysp) 740 { 741 struct sshsk_provider *skp = NULL; 742 int r = SSH_ERR_INTERNAL_ERROR; 743 struct sk_resident_key **rks = NULL; 744 size_t i, nrks = 0, nkeys = 0; 745 struct sshkey *key = NULL, **keys = NULL, **tmp; 746 uint8_t flags; 747 struct sk_option **opts = NULL; 748 749 debug("%s: provider \"%s\"%s", __func__, provider_path, 750 (pin != NULL && *pin != '\0') ? ", have-pin": ""); 751 752 if (keysp == NULL || nkeysp == NULL) 753 return SSH_ERR_INVALID_ARGUMENT; 754 *keysp = NULL; 755 *nkeysp = 0; 756 757 if ((r = make_options(device, NULL, &opts)) != 0) 758 goto out; 759 if ((skp = sshsk_open(provider_path)) == NULL) { 760 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 761 goto out; 762 } 763 if ((r = skp->sk_load_resident_keys(pin, opts, &rks, &nrks)) != 0) { 764 error("Provider \"%s\" returned failure %d", provider_path, r); 765 r = skerr_to_ssherr(r); 766 goto out; 767 } 768 for (i = 0; i < nrks; i++) { 769 debug3("%s: rk %zu: slot = %zu, alg = %d, application = \"%s\"", 770 __func__, i, rks[i]->slot, rks[i]->alg, 771 rks[i]->application); 772 /* XXX need better filter here */ 773 if (strncmp(rks[i]->application, "ssh:", 4) != 0) 774 continue; 775 switch (rks[i]->alg) { 776 case SSH_SK_ECDSA: 777 case SSH_SK_ED25519: 778 break; 779 default: 780 continue; 781 } 782 flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY; 783 if ((rks[i]->flags & SSH_SK_USER_VERIFICATION_REQD)) 784 flags |= SSH_SK_USER_VERIFICATION_REQD; 785 if ((r = sshsk_key_from_response(rks[i]->alg, 786 rks[i]->application, flags, &rks[i]->key, &key)) != 0) 787 goto out; 788 if ((tmp = recallocarray(keys, nkeys, nkeys + 1, 789 sizeof(*tmp))) == NULL) { 790 error("%s: recallocarray failed", __func__); 791 r = SSH_ERR_ALLOC_FAIL; 792 goto out; 793 } 794 keys = tmp; 795 keys[nkeys++] = key; 796 key = NULL; 797 /* XXX synthesise comment */ 798 } 799 /* success */ 800 *keysp = keys; 801 *nkeysp = nkeys; 802 keys = NULL; 803 nkeys = 0; 804 r = 0; 805 out: 806 sshsk_free_options(opts); 807 sshsk_free(skp); 808 sshsk_free_sk_resident_keys(rks, nrks); 809 sshkey_free(key); 810 if (nkeys != 0) { 811 for (i = 0; i < nkeys; i++) 812 sshkey_free(keys[i]); 813 free(keys); 814 } 815 return r; 816 } 817 818
Indexes created Mon Mar 16 00:23:04 UTC 2026