ssh-sk.c revision 1.3
1 /* $NetBSD: ssh-sk.c,v 1.3 2020/05/28 17:05:49 christos Exp $ */ 2 /* $OpenBSD: ssh-sk.c,v 1.30 2020/04/28 04:02:29 djm Exp $ */ 3 /* 4 * Copyright (c) 2019 Google LLC 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 #include "includes.h" 19 __RCSID("$NetBSD: ssh-sk.c,v 1.3 2020/05/28 17:05:49 christos Exp $"); 20 21 /* #define DEBUG_SK 1 */ 22 23 #include <dlfcn.h> 24 #include <stddef.h> 25 #include <stdint.h> 26 #include <string.h> 27 #include <stdio.h> 28 29 #ifdef WITH_OPENSSL 30 #include <openssl/objects.h> 31 #include <openssl/ec.h> 32 #endif /* WITH_OPENSSL */ 33 34 #include "log.h" 35 #include "misc.h" 36 #include "sshbuf.h" 37 #include "sshkey.h" 38 #include "ssherr.h" 39 #include "digest.h" 40 41 #include "ssh-sk.h" 42 #include "sk-api.h" 43 #include "crypto_api.h" 44 45 struct sshsk_provider { 46 char *path; 47 void *dlhandle; 48 49 /* Return the version of the middleware API */ 50 uint32_t (*sk_api_version)(void); 51 52 /* Enroll a U2F key (private key generation) */ 53 int (*sk_enroll)(int alg, const uint8_t *challenge, 54 size_t challenge_len, const char *application, uint8_t flags, 55 const char *pin, struct sk_option **opts, 56 struct sk_enroll_response **enroll_response); 57 58 /* Sign a challenge */ 59 int (*sk_sign)(int alg, const uint8_t *message, size_t message_len, 60 const char *application, 61 const uint8_t *key_handle, size_t key_handle_len, 62 uint8_t flags, const char *pin, struct sk_option **opts, 63 struct sk_sign_response **sign_response); 64 65 /* Enumerate resident keys */ 66 int (*sk_load_resident_keys)(const char *pin, struct sk_option **opts, 67 struct sk_resident_key ***rks, size_t *nrks); 68 }; 69 70 /* Built-in version */ 71 int ssh_sk_enroll(int alg, const uint8_t *challenge, 72 size_t challenge_len, const char *application, uint8_t flags, 73 const char *pin, struct sk_option **opts, 74 struct sk_enroll_response **enroll_response); 75 int ssh_sk_sign(int alg, const uint8_t *message, size_t message_len, 76 const char *application, 77 const uint8_t *key_handle, size_t key_handle_len, 78 uint8_t flags, const char *pin, struct sk_option **opts, 79 struct sk_sign_response **sign_response); 80 int ssh_sk_load_resident_keys(const char *pin, struct sk_option **opts, 81 struct sk_resident_key ***rks, size_t *nrks); 82 83 static void 84 sshsk_free(struct sshsk_provider *p) 85 { 86 if (p == NULL) 87 return; 88 free(p->path); 89 if (p->dlhandle != NULL) 90 dlclose(p->dlhandle); 91 free(p); 92 } 93 94 static struct sshsk_provider * 95 sshsk_open(const char *path) 96 { 97 struct sshsk_provider *ret = NULL; 98 uint32_t version; 99 100 if (path == NULL || *path == '\0') { 101 error("No FIDO SecurityKeyProvider specified"); 102 return NULL; 103 } 104 if ((ret = calloc(1, sizeof(*ret))) == NULL) { 105 error("%s: calloc failed", __func__); 106 return NULL; 107 } 108 if ((ret->path = strdup(path)) == NULL) { 109 error("%s: strdup failed", __func__); 110 goto fail; 111 } 112 /* Skip the rest if we're using the linked in middleware */ 113 if (strcasecmp(ret->path, "internal") == 0) { 114 ret->sk_enroll = ssh_sk_enroll; 115 ret->sk_sign = ssh_sk_sign; 116 ret->sk_load_resident_keys = ssh_sk_load_resident_keys; 117 return ret; 118 } 119 if ((ret->dlhandle = dlopen(path, RTLD_NOW)) == NULL) { 120 error("Provider \"%s\" dlopen failed: %s", path, dlerror()); 121 goto fail; 122 } 123 if ((ret->sk_api_version = dlsym(ret->dlhandle, 124 "sk_api_version")) == NULL) { 125 error("Provider \"%s\" dlsym(sk_api_version) failed: %s", 126 path, dlerror()); 127 goto fail; 128 } 129 version = ret->sk_api_version(); 130 debug("%s: provider %s implements version 0x%08lx", __func__, 131 ret->path, (u_long)version); 132 if ((version & SSH_SK_VERSION_MAJOR_MASK) != SSH_SK_VERSION_MAJOR) { 133 error("Provider \"%s\" implements unsupported " 134 "version 0x%08lx (supported: 0x%08lx)", 135 path, (u_long)version, (u_long)SSH_SK_VERSION_MAJOR); 136 goto fail; 137 } 138 if ((ret->sk_enroll = dlsym(ret->dlhandle, "sk_enroll")) == NULL) { 139 error("Provider %s dlsym(sk_enroll) failed: %s", 140 path, dlerror()); 141 goto fail; 142 } 143 if ((ret->sk_sign = dlsym(ret->dlhandle, "sk_sign")) == NULL) { 144 error("Provider \"%s\" dlsym(sk_sign) failed: %s", 145 path, dlerror()); 146 goto fail; 147 } 148 if ((ret->sk_load_resident_keys = dlsym(ret->dlhandle, 149 "sk_load_resident_keys")) == NULL) { 150 error("Provider \"%s\" dlsym(sk_load_resident_keys) " 151 "failed: %s", path, dlerror()); 152 goto fail; 153 } 154 /* success */ 155 return ret; 156 fail: 157 sshsk_free(ret); 158 return NULL; 159 } 160 161 static void 162 sshsk_free_enroll_response(struct sk_enroll_response *r) 163 { 164 if (r == NULL) 165 return; 166 freezero(r->key_handle, r->key_handle_len); 167 freezero(r->public_key, r->public_key_len); 168 freezero(r->signature, r->signature_len); 169 freezero(r->attestation_cert, r->attestation_cert_len); 170 freezero(r, sizeof(*r)); 171 } 172 173 static void 174 sshsk_free_sign_response(struct sk_sign_response *r) 175 { 176 if (r == NULL) 177 return; 178 freezero(r->sig_r, r->sig_r_len); 179 freezero(r->sig_s, r->sig_s_len); 180 freezero(r, sizeof(*r)); 181 } 182 183 #ifdef WITH_OPENSSL 184 /* Assemble key from response */ 185 static int 186 sshsk_ecdsa_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 187 { 188 struct sshkey *key = NULL; 189 struct sshbuf *b = NULL; 190 EC_POINT *q = NULL; 191 int r; 192 193 *keyp = NULL; 194 if ((key = sshkey_new(KEY_ECDSA_SK)) == NULL) { 195 error("%s: sshkey_new failed", __func__); 196 r = SSH_ERR_ALLOC_FAIL; 197 goto out; 198 } 199 key->ecdsa_nid = NID_X9_62_prime256v1; 200 if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL || 201 (q = EC_POINT_new(EC_KEY_get0_group(key->ecdsa))) == NULL || 202 (b = sshbuf_new()) == NULL) { 203 error("%s: allocation failed", __func__); 204 r = SSH_ERR_ALLOC_FAIL; 205 goto out; 206 } 207 if ((r = sshbuf_put_string(b, 208 resp->public_key, resp->public_key_len)) != 0) { 209 error("%s: buffer error: %s", __func__, ssh_err(r)); 210 goto out; 211 } 212 if ((r = sshbuf_get_ec(b, q, EC_KEY_get0_group(key->ecdsa))) != 0) { 213 error("%s: parse key: %s", __func__, ssh_err(r)); 214 r = SSH_ERR_INVALID_FORMAT; 215 goto out; 216 } 217 if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa), q) != 0) { 218 error("Authenticator returned invalid ECDSA key"); 219 r = SSH_ERR_KEY_INVALID_EC_VALUE; 220 goto out; 221 } 222 if (EC_KEY_set_public_key(key->ecdsa, q) != 1) { 223 /* XXX assume it is a allocation error */ 224 error("%s: allocation failed", __func__); 225 r = SSH_ERR_ALLOC_FAIL; 226 goto out; 227 } 228 /* success */ 229 *keyp = key; 230 key = NULL; /* transferred */ 231 r = 0; 232 out: 233 EC_POINT_free(q); 234 sshkey_free(key); 235 sshbuf_free(b); 236 return r; 237 } 238 #endif /* WITH_OPENSSL */ 239 240 static int 241 sshsk_ed25519_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 242 { 243 struct sshkey *key = NULL; 244 int r; 245 246 *keyp = NULL; 247 if (resp->public_key_len != ED25519_PK_SZ) { 248 error("%s: invalid size: %zu", __func__, resp->public_key_len); 249 r = SSH_ERR_INVALID_FORMAT; 250 goto out; 251 } 252 if ((key = sshkey_new(KEY_ED25519_SK)) == NULL) { 253 error("%s: sshkey_new failed", __func__); 254 r = SSH_ERR_ALLOC_FAIL; 255 goto out; 256 } 257 if ((key->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) { 258 error("%s: malloc failed", __func__); 259 r = SSH_ERR_ALLOC_FAIL; 260 goto out; 261 } 262 memcpy(key->ed25519_pk, resp->public_key, ED25519_PK_SZ); 263 /* success */ 264 *keyp = key; 265 key = NULL; /* transferred */ 266 r = 0; 267 out: 268 sshkey_free(key); 269 return r; 270 } 271 272 static int 273 sshsk_key_from_response(int alg, const char *application, uint8_t flags, 274 struct sk_enroll_response *resp, struct sshkey **keyp) 275 { 276 struct sshkey *key = NULL; 277 int r = SSH_ERR_INTERNAL_ERROR; 278 279 *keyp = NULL; 280 281 /* Check response validity */ 282 if (resp->public_key == NULL || resp->key_handle == NULL) { 283 error("%s: sk_enroll response invalid", __func__); 284 r = SSH_ERR_INVALID_FORMAT; 285 goto out; 286 } 287 switch (alg) { 288 #ifdef WITH_OPENSSL 289 case SSH_SK_ECDSA: 290 if ((r = sshsk_ecdsa_assemble(resp, &key)) != 0) 291 goto out; 292 break; 293 #endif /* WITH_OPENSSL */ 294 case SSH_SK_ED25519: 295 if ((r = sshsk_ed25519_assemble(resp, &key)) != 0) 296 goto out; 297 break; 298 default: 299 error("%s: unsupported algorithm %d", __func__, alg); 300 r = SSH_ERR_INVALID_ARGUMENT; 301 goto out; 302 } 303 key->sk_flags = flags; 304 if ((key->sk_key_handle = sshbuf_new()) == NULL || 305 (key->sk_reserved = sshbuf_new()) == NULL) { 306 error("%s: allocation failed", __func__); 307 r = SSH_ERR_ALLOC_FAIL; 308 goto out; 309 } 310 if ((key->sk_application = strdup(application)) == NULL) { 311 error("%s: strdup application failed", __func__); 312 r = SSH_ERR_ALLOC_FAIL; 313 goto out; 314 } 315 if ((r = sshbuf_put(key->sk_key_handle, resp->key_handle, 316 resp->key_handle_len)) != 0) { 317 error("%s: buffer error: %s", __func__, ssh_err(r)); 318 goto out; 319 } 320 /* success */ 321 r = 0; 322 *keyp = key; 323 key = NULL; 324 out: 325 sshkey_free(key); 326 return r; 327 } 328 329 static int 330 skerr_to_ssherr(int skerr) 331 { 332 switch (skerr) { 333 case SSH_SK_ERR_UNSUPPORTED: 334 return SSH_ERR_FEATURE_UNSUPPORTED; 335 case SSH_SK_ERR_PIN_REQUIRED: 336 return SSH_ERR_KEY_WRONG_PASSPHRASE; 337 case SSH_SK_ERR_DEVICE_NOT_FOUND: 338 return SSH_ERR_DEVICE_NOT_FOUND; 339 case SSH_SK_ERR_GENERAL: 340 default: 341 return SSH_ERR_INVALID_FORMAT; 342 } 343 } 344 345 static void 346 sshsk_free_options(struct sk_option **opts) 347 { 348 size_t i; 349 350 if (opts == NULL) 351 return; 352 for (i = 0; opts[i] != NULL; i++) { 353 free(opts[i]->name); 354 free(opts[i]->value); 355 free(opts[i]); 356 } 357 free(opts); 358 } 359 360 static int 361 sshsk_add_option(struct sk_option ***optsp, size_t *noptsp, 362 const char *name, const char *value, uint8_t required) 363 { 364 struct sk_option **opts = *optsp; 365 size_t nopts = *noptsp; 366 367 if ((opts = recallocarray(opts, nopts, nopts + 2, /* extra for NULL */ 368 sizeof(*opts))) == NULL) { 369 error("%s: array alloc failed", __func__); 370 return SSH_ERR_ALLOC_FAIL; 371 } 372 *optsp = opts; 373 *noptsp = nopts + 1; 374 if ((opts[nopts] = calloc(1, sizeof(**opts))) == NULL) { 375 error("%s: alloc failed", __func__); 376 return SSH_ERR_ALLOC_FAIL; 377 } 378 if ((opts[nopts]->name = strdup(name)) == NULL || 379 (opts[nopts]->value = strdup(value)) == NULL) { 380 error("%s: alloc failed", __func__); 381 return SSH_ERR_ALLOC_FAIL; 382 } 383 opts[nopts]->required = required; 384 return 0; 385 } 386 387 static int 388 make_options(const char *device, const char *user_id, 389 struct sk_option ***optsp) 390 { 391 struct sk_option **opts = NULL; 392 size_t nopts = 0; 393 int r, ret = SSH_ERR_INTERNAL_ERROR; 394 395 if (device != NULL && 396 (r = sshsk_add_option(&opts, &nopts, "device", device, 0)) != 0) { 397 ret = r; 398 goto out; 399 } 400 if (user_id != NULL && 401 (r = sshsk_add_option(&opts, &nopts, "user", user_id, 0)) != 0) { 402 ret = r; 403 goto out; 404 } 405 /* success */ 406 *optsp = opts; 407 opts = NULL; 408 nopts = 0; 409 ret = 0; 410 out: 411 sshsk_free_options(opts); 412 return ret; 413 } 414 415 int 416 sshsk_enroll(int type, const char *provider_path, const char *device, 417 const char *application, const char *userid, uint8_t flags, 418 const char *pin, struct sshbuf *challenge_buf, 419 struct sshkey **keyp, struct sshbuf *attest) 420 { 421 struct sshsk_provider *skp = NULL; 422 struct sshkey *key = NULL; 423 u_char randchall[32]; 424 const u_char *challenge; 425 size_t challenge_len; 426 struct sk_enroll_response *resp = NULL; 427 struct sk_option **opts = NULL; 428 int r = SSH_ERR_INTERNAL_ERROR; 429 int alg; 430 431 debug("%s: provider \"%s\", device \"%s\", application \"%s\", " 432 "userid \"%s\", flags 0x%02x, challenge len %zu%s", __func__, 433 provider_path, device, application, userid, flags, 434 challenge_buf == NULL ? 0 : sshbuf_len(challenge_buf), 435 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 436 437 *keyp = NULL; 438 if (attest) 439 sshbuf_reset(attest); 440 441 if ((r = make_options(device, userid, &opts)) != 0) 442 goto out; 443 444 switch (type) { 445 #ifdef WITH_OPENSSL 446 case KEY_ECDSA_SK: 447 alg = SSH_SK_ECDSA; 448 break; 449 #endif /* WITH_OPENSSL */ 450 case KEY_ED25519_SK: 451 alg = SSH_SK_ED25519; 452 break; 453 default: 454 error("%s: unsupported key type", __func__); 455 r = SSH_ERR_INVALID_ARGUMENT; 456 goto out; 457 } 458 if (provider_path == NULL) { 459 error("%s: missing provider", __func__); 460 r = SSH_ERR_INVALID_ARGUMENT; 461 goto out; 462 } 463 if (application == NULL || *application == '\0') { 464 error("%s: missing application", __func__); 465 r = SSH_ERR_INVALID_ARGUMENT; 466 goto out; 467 } 468 if (challenge_buf == NULL) { 469 debug("%s: using random challenge", __func__); 470 arc4random_buf(randchall, sizeof(randchall)); 471 challenge = randchall; 472 challenge_len = sizeof(randchall); 473 } else if (sshbuf_len(challenge_buf) == 0) { 474 error("Missing enrollment challenge"); 475 r = SSH_ERR_INVALID_ARGUMENT; 476 goto out; 477 } else { 478 challenge = sshbuf_ptr(challenge_buf); 479 challenge_len = sshbuf_len(challenge_buf); 480 debug3("%s: using explicit challenge len=%zd", 481 __func__, challenge_len); 482 } 483 if ((skp = sshsk_open(provider_path)) == NULL) { 484 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 485 goto out; 486 } 487 /* XXX validate flags? */ 488 /* enroll key */ 489 if ((r = skp->sk_enroll(alg, challenge, challenge_len, application, 490 flags, pin, opts, &resp)) != 0) { 491 debug("%s: provider \"%s\" returned failure %d", __func__, 492 provider_path, r); 493 r = skerr_to_ssherr(r); 494 goto out; 495 } 496 497 if ((r = sshsk_key_from_response(alg, application, flags, 498 resp, &key)) != 0) 499 goto out; 500 501 /* Optionally fill in the attestation information */ 502 if (attest != NULL) { 503 if ((r = sshbuf_put_cstring(attest, 504 "ssh-sk-attest-v00")) != 0 || 505 (r = sshbuf_put_string(attest, 506 resp->attestation_cert, resp->attestation_cert_len)) != 0 || 507 (r = sshbuf_put_string(attest, 508 resp->signature, resp->signature_len)) != 0 || 509 (r = sshbuf_put_u32(attest, 0)) != 0 || /* resvd flags */ 510 (r = sshbuf_put_string(attest, NULL, 0)) != 0 /* resvd */) { 511 error("%s: buffer error: %s", __func__, ssh_err(r)); 512 goto out; 513 } 514 } 515 /* success */ 516 *keyp = key; 517 key = NULL; /* transferred */ 518 r = 0; 519 out: 520 sshsk_free_options(opts); 521 sshsk_free(skp); 522 sshkey_free(key); 523 sshsk_free_enroll_response(resp); 524 explicit_bzero(randchall, sizeof(randchall)); 525 return r; 526 } 527 528 #ifdef WITH_OPENSSL 529 static int 530 sshsk_ecdsa_sig(struct sk_sign_response *resp, struct sshbuf *sig) 531 { 532 struct sshbuf *inner_sig = NULL; 533 int r = SSH_ERR_INTERNAL_ERROR; 534 535 /* Check response validity */ 536 if (resp->sig_r == NULL || resp->sig_s == NULL) { 537 error("%s: sk_sign response invalid", __func__); 538 r = SSH_ERR_INVALID_FORMAT; 539 goto out; 540 } 541 if ((inner_sig = sshbuf_new()) == NULL) { 542 r = SSH_ERR_ALLOC_FAIL; 543 goto out; 544 } 545 /* Prepare and append inner signature object */ 546 if ((r = sshbuf_put_bignum2_bytes(inner_sig, 547 resp->sig_r, resp->sig_r_len)) != 0 || 548 (r = sshbuf_put_bignum2_bytes(inner_sig, 549 resp->sig_s, resp->sig_s_len)) != 0) { 550 debug("%s: buffer error: %s", __func__, ssh_err(r)); 551 goto out; 552 } 553 if ((r = sshbuf_put_stringb(sig, inner_sig)) != 0 || 554 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 555 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 556 debug("%s: buffer error: %s", __func__, ssh_err(r)); 557 goto out; 558 } 559 #ifdef DEBUG_SK 560 fprintf(stderr, "%s: sig_r:\n", __func__); 561 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 562 fprintf(stderr, "%s: sig_s:\n", __func__); 563 sshbuf_dump_data(resp->sig_s, resp->sig_s_len, stderr); 564 fprintf(stderr, "%s: inner:\n", __func__); 565 sshbuf_dump(inner_sig, stderr); 566 #endif 567 r = 0; 568 out: 569 sshbuf_free(inner_sig); 570 return r; 571 } 572 #endif /* WITH_OPENSSL */ 573 574 static int 575 sshsk_ed25519_sig(struct sk_sign_response *resp, struct sshbuf *sig) 576 { 577 int r = SSH_ERR_INTERNAL_ERROR; 578 579 /* Check response validity */ 580 if (resp->sig_r == NULL) { 581 error("%s: sk_sign response invalid", __func__); 582 r = SSH_ERR_INVALID_FORMAT; 583 goto out; 584 } 585 if ((r = sshbuf_put_string(sig, 586 resp->sig_r, resp->sig_r_len)) != 0 || 587 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 588 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 589 debug("%s: buffer error: %s", __func__, ssh_err(r)); 590 goto out; 591 } 592 #ifdef DEBUG_SK 593 fprintf(stderr, "%s: sig_r:\n", __func__); 594 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 595 #endif 596 r = 0; 597 out: 598 return r; 599 } 600 601 int 602 sshsk_sign(const char *provider_path, struct sshkey *key, 603 u_char **sigp, size_t *lenp, const u_char *data, size_t datalen, 604 u_int compat, const char *pin) 605 { 606 struct sshsk_provider *skp = NULL; 607 int r = SSH_ERR_INTERNAL_ERROR; 608 int type, alg; 609 struct sk_sign_response *resp = NULL; 610 struct sshbuf *inner_sig = NULL, *sig = NULL; 611 struct sk_option **opts = NULL; 612 613 debug("%s: provider \"%s\", key %s, flags 0x%02x%s", __func__, 614 provider_path, sshkey_type(key), key->sk_flags, 615 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 616 617 if (sigp != NULL) 618 *sigp = NULL; 619 if (lenp != NULL) 620 *lenp = 0; 621 type = sshkey_type_plain(key->type); 622 switch (type) { 623 #ifdef WITH_OPENSSL 624 case KEY_ECDSA_SK: 625 alg = SSH_SK_ECDSA; 626 break; 627 #endif /* WITH_OPENSSL */ 628 case KEY_ED25519_SK: 629 alg = SSH_SK_ED25519; 630 break; 631 default: 632 return SSH_ERR_INVALID_ARGUMENT; 633 } 634 if (provider_path == NULL || 635 key->sk_key_handle == NULL || 636 key->sk_application == NULL || *key->sk_application == '\0') { 637 r = SSH_ERR_INVALID_ARGUMENT; 638 goto out; 639 } 640 if ((skp = sshsk_open(provider_path)) == NULL) { 641 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 642 goto out; 643 } 644 645 if ((r = skp->sk_sign(alg, data, datalen, key->sk_application, 646 sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle), 647 key->sk_flags, pin, opts, &resp)) != 0) { 648 debug("%s: sk_sign failed with code %d", __func__, r); 649 r = skerr_to_ssherr(r); 650 goto out; 651 } 652 /* Assemble signature */ 653 if ((sig = sshbuf_new()) == NULL) { 654 r = SSH_ERR_ALLOC_FAIL; 655 goto out; 656 } 657 if ((r = sshbuf_put_cstring(sig, sshkey_ssh_name_plain(key))) != 0) { 658 debug("%s: buffer error (outer): %s", __func__, ssh_err(r)); 659 goto out; 660 } 661 switch (type) { 662 #ifdef WITH_OPENSSL 663 case KEY_ECDSA_SK: 664 if ((r = sshsk_ecdsa_sig(resp, sig)) != 0) 665 goto out; 666 break; 667 #endif /* WITH_OPENSSL */ 668 case KEY_ED25519_SK: 669 if ((r = sshsk_ed25519_sig(resp, sig)) != 0) 670 goto out; 671 break; 672 } 673 #ifdef DEBUG_SK 674 fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n", 675 __func__, resp->flags, resp->counter); 676 fprintf(stderr, "%s: hashed message:\n", __func__); 677 sshbuf_dump_data(message, sizeof(message), stderr); 678 fprintf(stderr, "%s: sigbuf:\n", __func__); 679 sshbuf_dump(sig, stderr); 680 #endif 681 if (sigp != NULL) { 682 if ((*sigp = malloc(sshbuf_len(sig))) == NULL) { 683 r = SSH_ERR_ALLOC_FAIL; 684 goto out; 685 } 686 memcpy(*sigp, sshbuf_ptr(sig), sshbuf_len(sig)); 687 } 688 if (lenp != NULL) 689 *lenp = sshbuf_len(sig); 690 /* success */ 691 r = 0; 692 out: 693 sshsk_free_options(opts); 694 sshsk_free(skp); 695 sshsk_free_sign_response(resp); 696 sshbuf_free(sig); 697 sshbuf_free(inner_sig); 698 return r; 699 } 700 701 static void 702 sshsk_free_sk_resident_keys(struct sk_resident_key **rks, size_t nrks) 703 { 704 size_t i; 705 706 if (nrks == 0 || rks == NULL) 707 return; 708 for (i = 0; i < nrks; i++) { 709 free(rks[i]->application); 710 freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len); 711 freezero(rks[i]->key.public_key, rks[i]->key.public_key_len); 712 freezero(rks[i]->key.signature, rks[i]->key.signature_len); 713 freezero(rks[i]->key.attestation_cert, 714 rks[i]->key.attestation_cert_len); 715 freezero(rks[i], sizeof(**rks)); 716 } 717 free(rks); 718 } 719 720 int 721 sshsk_load_resident(const char *provider_path, const char *device, 722 const char *pin, struct sshkey ***keysp, size_t *nkeysp) 723 { 724 struct sshsk_provider *skp = NULL; 725 int r = SSH_ERR_INTERNAL_ERROR; 726 struct sk_resident_key **rks = NULL; 727 size_t i, nrks = 0, nkeys = 0; 728 struct sshkey *key = NULL, **keys = NULL, **tmp; 729 uint8_t flags; 730 struct sk_option **opts = NULL; 731 732 debug("%s: provider \"%s\"%s", __func__, provider_path, 733 (pin != NULL && *pin != '\0') ? ", have-pin": ""); 734 735 if (keysp == NULL || nkeysp == NULL) 736 return SSH_ERR_INVALID_ARGUMENT; 737 *keysp = NULL; 738 *nkeysp = 0; 739 740 if ((r = make_options(device, NULL, &opts)) != 0) 741 goto out; 742 if ((skp = sshsk_open(provider_path)) == NULL) { 743 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 744 goto out; 745 } 746 if ((r = skp->sk_load_resident_keys(pin, opts, &rks, &nrks)) != 0) { 747 error("Provider \"%s\" returned failure %d", provider_path, r); 748 r = skerr_to_ssherr(r); 749 goto out; 750 } 751 for (i = 0; i < nrks; i++) { 752 debug3("%s: rk %zu: slot = %zu, alg = %d, application = \"%s\"", 753 __func__, i, rks[i]->slot, rks[i]->alg, 754 rks[i]->application); 755 /* XXX need better filter here */ 756 if (strncmp(rks[i]->application, "ssh:", 4) != 0) 757 continue; 758 switch (rks[i]->alg) { 759 case SSH_SK_ECDSA: 760 case SSH_SK_ED25519: 761 break; 762 default: 763 continue; 764 } 765 /* XXX where to get flags? */ 766 flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY; 767 if ((r = sshsk_key_from_response(rks[i]->alg, 768 rks[i]->application, flags, &rks[i]->key, &key)) != 0) 769 goto out; 770 if ((tmp = recallocarray(keys, nkeys, nkeys + 1, 771 sizeof(*tmp))) == NULL) { 772 error("%s: recallocarray failed", __func__); 773 r = SSH_ERR_ALLOC_FAIL; 774 goto out; 775 } 776 keys = tmp; 777 keys[nkeys++] = key; 778 key = NULL; 779 /* XXX synthesise comment */ 780 } 781 /* success */ 782 *keysp = keys; 783 *nkeysp = nkeys; 784 keys = NULL; 785 nkeys = 0; 786 r = 0; 787 out: 788 sshsk_free_options(opts); 789 sshsk_free(skp); 790 sshsk_free_sk_resident_keys(rks, nrks); 791 sshkey_free(key); 792 if (nkeys != 0) { 793 for (i = 0; i < nkeys; i++) 794 sshkey_free(keys[i]); 795 free(keys); 796 } 797 return r; 798 } 799 800
Indexes created Mon Mar 16 00:23:04 UTC 2026