1 /* $OpenBSD: ssh-sk.c,v 1.39 2022/07/20 03:29:14 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 "includes.h" 21 22 #ifdef ENABLE_SK 23 24 #include <dlfcn.h> 25 #include <stddef.h> 26 #ifdef HAVE_STDINT_H 27 # include <stdint.h> 28 #endif 29 #include <string.h> 30 #include <stdio.h> 31 32 #if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC) 33 #include <openssl/objects.h> 34 #include <openssl/ec.h> 35 #endif /* WITH_OPENSSL && OPENSSL_HAS_ECC */ 36 37 #include "log.h" 38 #include "misc.h" 39 #include "sshbuf.h" 40 #include "sshkey.h" 41 #include "ssherr.h" 42 #include "digest.h" 43 44 #include "ssh-sk.h" 45 #include "sk-api.h" 46 #include "crypto_api.h" 47 48 /* 49 * Almost every use of OpenSSL in this file is for ECDSA-NISTP256. 50 * This is strictly a larger hammer than necessary, but it reduces changes 51 * with upstream. 52 */ 53 #ifndef OPENSSL_HAS_ECC 54 # undef WITH_OPENSSL 55 #endif 56 57 struct sshsk_provider { 58 char *path; 59 void *dlhandle; 60 61 /* Return the version of the middleware API */ 62 uint32_t (*sk_api_version)(void); 63 64 /* Enroll a U2F key (private key generation) */ 65 int (*sk_enroll)(int alg, const uint8_t *challenge, 66 size_t challenge_len, const char *application, uint8_t flags, 67 const char *pin, struct sk_option **opts, 68 struct sk_enroll_response **enroll_response); 69 70 /* Sign a challenge */ 71 int (*sk_sign)(int alg, const uint8_t *message, size_t message_len, 72 const char *application, 73 const uint8_t *key_handle, size_t key_handle_len, 74 uint8_t flags, const char *pin, struct sk_option **opts, 75 struct sk_sign_response **sign_response); 76 77 /* Enumerate resident keys */ 78 int (*sk_load_resident_keys)(const char *pin, struct sk_option **opts, 79 struct sk_resident_key ***rks, size_t *nrks); 80 }; 81 82 /* Built-in version */ 83 int ssh_sk_enroll(int alg, const uint8_t *challenge, 84 size_t challenge_len, const char *application, uint8_t flags, 85 const char *pin, struct sk_option **opts, 86 struct sk_enroll_response **enroll_response); 87 int ssh_sk_sign(int alg, const uint8_t *message, size_t message_len, 88 const char *application, 89 const uint8_t *key_handle, size_t key_handle_len, 90 uint8_t flags, const char *pin, struct sk_option **opts, 91 struct sk_sign_response **sign_response); 92 int ssh_sk_load_resident_keys(const char *pin, struct sk_option **opts, 93 struct sk_resident_key ***rks, size_t *nrks); 94 95 static void 96 sshsk_free(struct sshsk_provider *p) 97 { 98 if (p == NULL) 99 return; 100 free(p->path); 101 if (p->dlhandle != NULL) 102 dlclose(p->dlhandle); 103 free(p); 104 } 105 106 static struct sshsk_provider * 107 sshsk_open(const char *path) 108 { 109 struct sshsk_provider *ret = NULL; 110 uint32_t version; 111 112 if (path == NULL || *path == '\0') { 113 error("No FIDO SecurityKeyProvider specified"); 114 return NULL; 115 } 116 if ((ret = calloc(1, sizeof(*ret))) == NULL) { 117 error_f("calloc failed"); 118 return NULL; 119 } 120 if ((ret->path = strdup(path)) == NULL) { 121 error_f("strdup failed"); 122 goto fail; 123 } 124 /* Skip the rest if we're using the linked in middleware */ 125 if (strcasecmp(ret->path, "internal") == 0) { 126 #ifdef ENABLE_SK_INTERNAL 127 ret->sk_enroll = ssh_sk_enroll; 128 ret->sk_sign = ssh_sk_sign; 129 ret->sk_load_resident_keys = ssh_sk_load_resident_keys; 130 return ret; 131 #else 132 error("internal security key support not enabled"); 133 goto fail; 134 #endif 135 } 136 if ((ret->dlhandle = dlopen(path, RTLD_NOW)) == NULL) { 137 error("Provider \"%s\" dlopen failed: %s", path, dlerror()); 138 goto fail; 139 } 140 if ((ret->sk_api_version = dlsym(ret->dlhandle, 141 "sk_api_version")) == NULL) { 142 error("Provider \"%s\" dlsym(sk_api_version) failed: %s", 143 path, dlerror()); 144 goto fail; 145 } 146 version = ret->sk_api_version(); 147 debug_f("provider %s implements version 0x%08lx", ret->path, 148 (u_long)version); 149 if ((version & SSH_SK_VERSION_MAJOR_MASK) != SSH_SK_VERSION_MAJOR) { 150 error("Provider \"%s\" implements unsupported " 151 "version 0x%08lx (supported: 0x%08lx)", 152 path, (u_long)version, (u_long)SSH_SK_VERSION_MAJOR); 153 goto fail; 154 } 155 if ((ret->sk_enroll = dlsym(ret->dlhandle, "sk_enroll")) == NULL) { 156 error("Provider %s dlsym(sk_enroll) failed: %s", 157 path, dlerror()); 158 goto fail; 159 } 160 if ((ret->sk_sign = dlsym(ret->dlhandle, "sk_sign")) == NULL) { 161 error("Provider \"%s\" dlsym(sk_sign) failed: %s", 162 path, dlerror()); 163 goto fail; 164 } 165 if ((ret->sk_load_resident_keys = dlsym(ret->dlhandle, 166 "sk_load_resident_keys")) == NULL) { 167 error("Provider \"%s\" dlsym(sk_load_resident_keys) " 168 "failed: %s", path, dlerror()); 169 goto fail; 170 } 171 /* success */ 172 return ret; 173 fail: 174 sshsk_free(ret); 175 return NULL; 176 } 177 178 static void 179 sshsk_free_enroll_response(struct sk_enroll_response *r) 180 { 181 if (r == NULL) 182 return; 183 freezero(r->key_handle, r->key_handle_len); 184 freezero(r->public_key, r->public_key_len); 185 freezero(r->signature, r->signature_len); 186 freezero(r->attestation_cert, r->attestation_cert_len); 187 freezero(r->authdata, r->authdata_len); 188 freezero(r, sizeof(*r)); 189 } 190 191 static void 192 sshsk_free_sign_response(struct sk_sign_response *r) 193 { 194 if (r == NULL) 195 return; 196 freezero(r->sig_r, r->sig_r_len); 197 freezero(r->sig_s, r->sig_s_len); 198 freezero(r, sizeof(*r)); 199 } 200 201 #ifdef WITH_OPENSSL 202 /* Assemble key from response */ 203 static int 204 sshsk_ecdsa_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 205 { 206 struct sshkey *key = NULL; 207 struct sshbuf *b = NULL; 208 EC_POINT *q = NULL; 209 int r; 210 211 *keyp = NULL; 212 if ((key = sshkey_new(KEY_ECDSA_SK)) == NULL) { 213 error_f("sshkey_new failed"); 214 r = SSH_ERR_ALLOC_FAIL; 215 goto out; 216 } 217 key->ecdsa_nid = NID_X9_62_prime256v1; 218 if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL || 219 (q = EC_POINT_new(EC_KEY_get0_group(key->ecdsa))) == NULL || 220 (b = sshbuf_new()) == NULL) { 221 error_f("allocation failed"); 222 r = SSH_ERR_ALLOC_FAIL; 223 goto out; 224 } 225 if ((r = sshbuf_put_string(b, 226 resp->public_key, resp->public_key_len)) != 0) { 227 error_fr(r, "sshbuf_put_string"); 228 goto out; 229 } 230 if ((r = sshbuf_get_ec(b, q, EC_KEY_get0_group(key->ecdsa))) != 0) { 231 error_fr(r, "parse"); 232 r = SSH_ERR_INVALID_FORMAT; 233 goto out; 234 } 235 if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa), q) != 0) { 236 error("Authenticator returned invalid ECDSA key"); 237 r = SSH_ERR_KEY_INVALID_EC_VALUE; 238 goto out; 239 } 240 if (EC_KEY_set_public_key(key->ecdsa, q) != 1) { 241 /* XXX assume it is a allocation error */ 242 error_f("allocation failed"); 243 r = SSH_ERR_ALLOC_FAIL; 244 goto out; 245 } 246 /* success */ 247 *keyp = key; 248 key = NULL; /* transferred */ 249 r = 0; 250 out: 251 EC_POINT_free(q); 252 sshkey_free(key); 253 sshbuf_free(b); 254 return r; 255 } 256 #endif /* WITH_OPENSSL */ 257 258 static int 259 sshsk_ed25519_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 260 { 261 struct sshkey *key = NULL; 262 int r; 263 264 *keyp = NULL; 265 if (resp->public_key_len != ED25519_PK_SZ) { 266 error_f("invalid size: %zu", resp->public_key_len); 267 r = SSH_ERR_INVALID_FORMAT; 268 goto out; 269 } 270 if ((key = sshkey_new(KEY_ED25519_SK)) == NULL) { 271 error_f("sshkey_new failed"); 272 r = SSH_ERR_ALLOC_FAIL; 273 goto out; 274 } 275 if ((key->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) { 276 error_f("malloc failed"); 277 r = SSH_ERR_ALLOC_FAIL; 278 goto out; 279 } 280 memcpy(key->ed25519_pk, resp->public_key, ED25519_PK_SZ); 281 /* success */ 282 *keyp = key; 283 key = NULL; /* transferred */ 284 r = 0; 285 out: 286 sshkey_free(key); 287 return r; 288 } 289 290 static int 291 sshsk_key_from_response(int alg, const char *application, uint8_t flags, 292 struct sk_enroll_response *resp, struct sshkey **keyp) 293 { 294 struct sshkey *key = NULL; 295 int r = SSH_ERR_INTERNAL_ERROR; 296 297 *keyp = NULL; 298 299 /* Check response validity */ 300 if (resp->public_key == NULL || resp->key_handle == NULL) { 301 error_f("sk_enroll response invalid"); 302 r = SSH_ERR_INVALID_FORMAT; 303 goto out; 304 } 305 switch (alg) { 306 #ifdef WITH_OPENSSL 307 case SSH_SK_ECDSA: 308 if ((r = sshsk_ecdsa_assemble(resp, &key)) != 0) 309 goto out; 310 break; 311 #endif /* WITH_OPENSSL */ 312 case SSH_SK_ED25519: 313 if ((r = sshsk_ed25519_assemble(resp, &key)) != 0) 314 goto out; 315 break; 316 default: 317 error_f("unsupported algorithm %d", alg); 318 r = SSH_ERR_INVALID_ARGUMENT; 319 goto out; 320 } 321 key->sk_flags = flags; 322 if ((key->sk_key_handle = sshbuf_new()) == NULL || 323 (key->sk_reserved = sshbuf_new()) == NULL) { 324 error_f("allocation failed"); 325 r = SSH_ERR_ALLOC_FAIL; 326 goto out; 327 } 328 if ((key->sk_application = strdup(application)) == NULL) { 329 error_f("strdup application failed"); 330 r = SSH_ERR_ALLOC_FAIL; 331 goto out; 332 } 333 if ((r = sshbuf_put(key->sk_key_handle, resp->key_handle, 334 resp->key_handle_len)) != 0) { 335 error_fr(r, "put key handle"); 336 goto out; 337 } 338 /* success */ 339 r = 0; 340 *keyp = key; 341 key = NULL; 342 out: 343 sshkey_free(key); 344 return r; 345 } 346 347 static int 348 skerr_to_ssherr(int skerr) 349 { 350 switch (skerr) { 351 case SSH_SK_ERR_UNSUPPORTED: 352 return SSH_ERR_FEATURE_UNSUPPORTED; 353 case SSH_SK_ERR_PIN_REQUIRED: 354 return SSH_ERR_KEY_WRONG_PASSPHRASE; 355 case SSH_SK_ERR_DEVICE_NOT_FOUND: 356 return SSH_ERR_DEVICE_NOT_FOUND; 357 case SSH_SK_ERR_CREDENTIAL_EXISTS: 358 return SSH_ERR_KEY_BAD_PERMISSIONS; 359 case SSH_SK_ERR_GENERAL: 360 default: 361 return SSH_ERR_INVALID_FORMAT; 362 } 363 } 364 365 static void 366 sshsk_free_options(struct sk_option **opts) 367 { 368 size_t i; 369 370 if (opts == NULL) 371 return; 372 for (i = 0; opts[i] != NULL; i++) { 373 free(opts[i]->name); 374 free(opts[i]->value); 375 free(opts[i]); 376 } 377 free(opts); 378 } 379 380 static int 381 sshsk_add_option(struct sk_option ***optsp, size_t *noptsp, 382 const char *name, const char *value, uint8_t required) 383 { 384 struct sk_option **opts = *optsp; 385 size_t nopts = *noptsp; 386 387 if ((opts = recallocarray(opts, nopts, nopts + 2, /* extra for NULL */ 388 sizeof(*opts))) == NULL) { 389 error_f("array alloc failed"); 390 return SSH_ERR_ALLOC_FAIL; 391 } 392 *optsp = opts; 393 *noptsp = nopts + 1; 394 if ((opts[nopts] = calloc(1, sizeof(**opts))) == NULL) { 395 error_f("alloc failed"); 396 return SSH_ERR_ALLOC_FAIL; 397 } 398 if ((opts[nopts]->name = strdup(name)) == NULL || 399 (opts[nopts]->value = strdup(value)) == NULL) { 400 error_f("alloc failed"); 401 return SSH_ERR_ALLOC_FAIL; 402 } 403 opts[nopts]->required = required; 404 return 0; 405 } 406 407 static int 408 make_options(const char *device, const char *user_id, 409 struct sk_option ***optsp) 410 { 411 struct sk_option **opts = NULL; 412 size_t nopts = 0; 413 int r, ret = SSH_ERR_INTERNAL_ERROR; 414 415 if (device != NULL && 416 (r = sshsk_add_option(&opts, &nopts, "device", device, 0)) != 0) { 417 ret = r; 418 goto out; 419 } 420 if (user_id != NULL && 421 (r = sshsk_add_option(&opts, &nopts, "user", user_id, 0)) != 0) { 422 ret = r; 423 goto out; 424 } 425 /* success */ 426 *optsp = opts; 427 opts = NULL; 428 nopts = 0; 429 ret = 0; 430 out: 431 sshsk_free_options(opts); 432 return ret; 433 } 434 435 436 static int 437 fill_attestation_blob(const struct sk_enroll_response *resp, 438 struct sshbuf *attest) 439 { 440 int r; 441 442 if (attest == NULL) 443 return 0; /* nothing to do */ 444 if ((r = sshbuf_put_cstring(attest, "ssh-sk-attest-v01")) != 0 || 445 (r = sshbuf_put_string(attest, 446 resp->attestation_cert, resp->attestation_cert_len)) != 0 || 447 (r = sshbuf_put_string(attest, 448 resp->signature, resp->signature_len)) != 0 || 449 (r = sshbuf_put_string(attest, 450 resp->authdata, resp->authdata_len)) != 0 || 451 (r = sshbuf_put_u32(attest, 0)) != 0 || /* resvd flags */ 452 (r = sshbuf_put_string(attest, NULL, 0)) != 0 /* resvd */) { 453 error_fr(r, "compose"); 454 return r; 455 } 456 /* success */ 457 return 0; 458 } 459 460 int 461 sshsk_enroll(int type, const char *provider_path, const char *device, 462 const char *application, const char *userid, uint8_t flags, 463 const char *pin, struct sshbuf *challenge_buf, 464 struct sshkey **keyp, struct sshbuf *attest) 465 { 466 struct sshsk_provider *skp = NULL; 467 struct sshkey *key = NULL; 468 u_char randchall[32]; 469 const u_char *challenge; 470 size_t challenge_len; 471 struct sk_enroll_response *resp = NULL; 472 struct sk_option **opts = NULL; 473 int r = SSH_ERR_INTERNAL_ERROR; 474 int alg; 475 476 debug_f("provider \"%s\", device \"%s\", application \"%s\", " 477 "userid \"%s\", flags 0x%02x, challenge len %zu%s", 478 provider_path, device, application, userid, flags, 479 challenge_buf == NULL ? 0 : sshbuf_len(challenge_buf), 480 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 481 482 *keyp = NULL; 483 if (attest) 484 sshbuf_reset(attest); 485 486 if ((r = make_options(device, userid, &opts)) != 0) 487 goto out; 488 489 switch (type) { 490 #ifdef WITH_OPENSSL 491 case KEY_ECDSA_SK: 492 alg = SSH_SK_ECDSA; 493 break; 494 #endif /* WITH_OPENSSL */ 495 case KEY_ED25519_SK: 496 alg = SSH_SK_ED25519; 497 break; 498 default: 499 error_f("unsupported key type"); 500 r = SSH_ERR_INVALID_ARGUMENT; 501 goto out; 502 } 503 if (provider_path == NULL) { 504 error_f("missing provider"); 505 r = SSH_ERR_INVALID_ARGUMENT; 506 goto out; 507 } 508 if (application == NULL || *application == '\0') { 509 error_f("missing application"); 510 r = SSH_ERR_INVALID_ARGUMENT; 511 goto out; 512 } 513 if (challenge_buf == NULL) { 514 debug_f("using random challenge"); 515 arc4random_buf(randchall, sizeof(randchall)); 516 challenge = randchall; 517 challenge_len = sizeof(randchall); 518 } else if (sshbuf_len(challenge_buf) == 0) { 519 error("Missing enrollment challenge"); 520 r = SSH_ERR_INVALID_ARGUMENT; 521 goto out; 522 } else { 523 challenge = sshbuf_ptr(challenge_buf); 524 challenge_len = sshbuf_len(challenge_buf); 525 debug3_f("using explicit challenge len=%zd", challenge_len); 526 } 527 if ((skp = sshsk_open(provider_path)) == NULL) { 528 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 529 goto out; 530 } 531 /* XXX validate flags? */ 532 /* enroll key */ 533 if ((r = skp->sk_enroll(alg, challenge, challenge_len, application, 534 flags, pin, opts, &resp)) != 0) { 535 debug_f("provider \"%s\" failure %d", provider_path, r); 536 r = skerr_to_ssherr(r); 537 goto out; 538 } 539 540 if ((r = sshsk_key_from_response(alg, application, resp->flags, 541 resp, &key)) != 0) 542 goto out; 543 544 /* Optionally fill in the attestation information */ 545 if ((r = fill_attestation_blob(resp, attest)) != 0) 546 goto out; 547 548 /* success */ 549 *keyp = key; 550 key = NULL; /* transferred */ 551 r = 0; 552 out: 553 sshsk_free_options(opts); 554 sshsk_free(skp); 555 sshkey_free(key); 556 sshsk_free_enroll_response(resp); 557 explicit_bzero(randchall, sizeof(randchall)); 558 return r; 559 } 560 561 #ifdef WITH_OPENSSL 562 static int 563 sshsk_ecdsa_sig(struct sk_sign_response *resp, struct sshbuf *sig) 564 { 565 struct sshbuf *inner_sig = NULL; 566 int r = SSH_ERR_INTERNAL_ERROR; 567 568 /* Check response validity */ 569 if (resp->sig_r == NULL || resp->sig_s == NULL) { 570 error_f("sk_sign response invalid"); 571 r = SSH_ERR_INVALID_FORMAT; 572 goto out; 573 } 574 if ((inner_sig = sshbuf_new()) == NULL) { 575 r = SSH_ERR_ALLOC_FAIL; 576 goto out; 577 } 578 /* Prepare and append inner signature object */ 579 if ((r = sshbuf_put_bignum2_bytes(inner_sig, 580 resp->sig_r, resp->sig_r_len)) != 0 || 581 (r = sshbuf_put_bignum2_bytes(inner_sig, 582 resp->sig_s, resp->sig_s_len)) != 0) { 583 error_fr(r, "compose inner"); 584 goto out; 585 } 586 if ((r = sshbuf_put_stringb(sig, inner_sig)) != 0 || 587 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 588 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 589 error_fr(r, "compose"); 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 fprintf(stderr, "%s: sig_s:\n", __func__); 596 sshbuf_dump_data(resp->sig_s, resp->sig_s_len, stderr); 597 fprintf(stderr, "%s: inner:\n", __func__); 598 sshbuf_dump(inner_sig, stderr); 599 #endif 600 r = 0; 601 out: 602 sshbuf_free(inner_sig); 603 return r; 604 } 605 #endif /* WITH_OPENSSL */ 606 607 static int 608 sshsk_ed25519_sig(struct sk_sign_response *resp, struct sshbuf *sig) 609 { 610 int r = SSH_ERR_INTERNAL_ERROR; 611 612 /* Check response validity */ 613 if (resp->sig_r == NULL) { 614 error_f("sk_sign response invalid"); 615 r = SSH_ERR_INVALID_FORMAT; 616 goto out; 617 } 618 if ((r = sshbuf_put_string(sig, 619 resp->sig_r, resp->sig_r_len)) != 0 || 620 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 621 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 622 error_fr(r, "compose"); 623 goto out; 624 } 625 #ifdef DEBUG_SK 626 fprintf(stderr, "%s: sig_r:\n", __func__); 627 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 628 #endif 629 r = 0; 630 out: 631 return r; 632 } 633 634 int 635 sshsk_sign(const char *provider_path, struct sshkey *key, 636 u_char **sigp, size_t *lenp, const u_char *data, size_t datalen, 637 u_int compat, const char *pin) 638 { 639 struct sshsk_provider *skp = NULL; 640 int r = SSH_ERR_INTERNAL_ERROR; 641 int type, alg; 642 struct sk_sign_response *resp = NULL; 643 struct sshbuf *inner_sig = NULL, *sig = NULL; 644 struct sk_option **opts = NULL; 645 646 debug_f("provider \"%s\", key %s, flags 0x%02x%s", 647 provider_path, sshkey_type(key), key->sk_flags, 648 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 649 650 if (sigp != NULL) 651 *sigp = NULL; 652 if (lenp != NULL) 653 *lenp = 0; 654 type = sshkey_type_plain(key->type); 655 switch (type) { 656 #ifdef WITH_OPENSSL 657 case KEY_ECDSA_SK: 658 alg = SSH_SK_ECDSA; 659 break; 660 #endif /* WITH_OPENSSL */ 661 case KEY_ED25519_SK: 662 alg = SSH_SK_ED25519; 663 break; 664 default: 665 return SSH_ERR_INVALID_ARGUMENT; 666 } 667 if (provider_path == NULL || 668 key->sk_key_handle == NULL || 669 key->sk_application == NULL || *key->sk_application == '\0') { 670 r = SSH_ERR_INVALID_ARGUMENT; 671 goto out; 672 } 673 if ((skp = sshsk_open(provider_path)) == NULL) { 674 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 675 goto out; 676 } 677 #ifdef DEBUG_SK 678 fprintf(stderr, "%s: sk_flags = 0x%02x, sk_application = \"%s\"\n", 679 __func__, key->sk_flags, key->sk_application); 680 fprintf(stderr, "%s: sk_key_handle:\n", __func__); 681 sshbuf_dump(key->sk_key_handle, stderr); 682 #endif 683 if ((r = skp->sk_sign(alg, data, datalen, key->sk_application, 684 sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle), 685 key->sk_flags, pin, opts, &resp)) != 0) { 686 debug_f("sk_sign failed with code %d", r); 687 r = skerr_to_ssherr(r); 688 goto out; 689 } 690 /* Assemble signature */ 691 if ((sig = sshbuf_new()) == NULL) { 692 r = SSH_ERR_ALLOC_FAIL; 693 goto out; 694 } 695 if ((r = sshbuf_put_cstring(sig, sshkey_ssh_name_plain(key))) != 0) { 696 error_fr(r, "compose outer"); 697 goto out; 698 } 699 switch (type) { 700 #ifdef WITH_OPENSSL 701 case KEY_ECDSA_SK: 702 if ((r = sshsk_ecdsa_sig(resp, sig)) != 0) 703 goto out; 704 break; 705 #endif /* WITH_OPENSSL */ 706 case KEY_ED25519_SK: 707 if ((r = sshsk_ed25519_sig(resp, sig)) != 0) 708 goto out; 709 break; 710 } 711 #ifdef DEBUG_SK 712 fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n", 713 __func__, resp->flags, resp->counter); 714 fprintf(stderr, "%s: data to sign:\n", __func__); 715 sshbuf_dump_data(data, datalen, stderr); 716 fprintf(stderr, "%s: sigbuf:\n", __func__); 717 sshbuf_dump(sig, stderr); 718 #endif 719 if (sigp != NULL) { 720 if ((*sigp = malloc(sshbuf_len(sig))) == NULL) { 721 r = SSH_ERR_ALLOC_FAIL; 722 goto out; 723 } 724 memcpy(*sigp, sshbuf_ptr(sig), sshbuf_len(sig)); 725 } 726 if (lenp != NULL) 727 *lenp = sshbuf_len(sig); 728 /* success */ 729 r = 0; 730 out: 731 sshsk_free_options(opts); 732 sshsk_free(skp); 733 sshsk_free_sign_response(resp); 734 sshbuf_free(sig); 735 sshbuf_free(inner_sig); 736 return r; 737 } 738 739 static void 740 sshsk_free_sk_resident_keys(struct sk_resident_key **rks, size_t nrks) 741 { 742 size_t i; 743 744 if (nrks == 0 || rks == NULL) 745 return; 746 for (i = 0; i < nrks; i++) { 747 free(rks[i]->application); 748 freezero(rks[i]->user_id, rks[i]->user_id_len); 749 freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len); 750 freezero(rks[i]->key.public_key, rks[i]->key.public_key_len); 751 freezero(rks[i]->key.signature, rks[i]->key.signature_len); 752 freezero(rks[i]->key.attestation_cert, 753 rks[i]->key.attestation_cert_len); 754 freezero(rks[i], sizeof(**rks)); 755 } 756 free(rks); 757 } 758 759 static void 760 sshsk_free_resident_key(struct sshsk_resident_key *srk) 761 { 762 if (srk == NULL) 763 return; 764 sshkey_free(srk->key); 765 freezero(srk->user_id, srk->user_id_len); 766 free(srk); 767 } 768 769 770 void 771 sshsk_free_resident_keys(struct sshsk_resident_key **srks, size_t nsrks) 772 { 773 size_t i; 774 775 if (srks == NULL || nsrks == 0) 776 return; 777 778 for (i = 0; i < nsrks; i++) 779 sshsk_free_resident_key(srks[i]); 780 free(srks); 781 } 782 783 int 784 sshsk_load_resident(const char *provider_path, const char *device, 785 const char *pin, u_int flags, struct sshsk_resident_key ***srksp, 786 size_t *nsrksp) 787 { 788 struct sshsk_provider *skp = NULL; 789 int r = SSH_ERR_INTERNAL_ERROR; 790 struct sk_resident_key **rks = NULL; 791 size_t i, nrks = 0, nsrks = 0; 792 struct sshkey *key = NULL; 793 struct sshsk_resident_key *srk = NULL, **srks = NULL, **tmp; 794 uint8_t sk_flags; 795 struct sk_option **opts = NULL; 796 797 debug_f("provider \"%s\"%s", provider_path, 798 (pin != NULL && *pin != '\0') ? ", have-pin": ""); 799 800 if (srksp == NULL || nsrksp == NULL) 801 return SSH_ERR_INVALID_ARGUMENT; 802 *srksp = NULL; 803 *nsrksp = 0; 804 805 if ((r = make_options(device, NULL, &opts)) != 0) 806 goto out; 807 if ((skp = sshsk_open(provider_path)) == NULL) { 808 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 809 goto out; 810 } 811 if ((r = skp->sk_load_resident_keys(pin, opts, &rks, &nrks)) != 0) { 812 error("Provider \"%s\" returned failure %d", provider_path, r); 813 r = skerr_to_ssherr(r); 814 goto out; 815 } 816 for (i = 0; i < nrks; i++) { 817 debug3_f("rk %zu: slot %zu, alg %d, app \"%s\", uidlen %zu", 818 i, rks[i]->slot, rks[i]->alg, rks[i]->application, 819 rks[i]->user_id_len); 820 /* XXX need better filter here */ 821 if (strncmp(rks[i]->application, "ssh:", 4) != 0) 822 continue; 823 switch (rks[i]->alg) { 824 case SSH_SK_ECDSA: 825 case SSH_SK_ED25519: 826 break; 827 default: 828 continue; 829 } 830 sk_flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY; 831 if ((rks[i]->flags & SSH_SK_USER_VERIFICATION_REQD)) 832 sk_flags |= SSH_SK_USER_VERIFICATION_REQD; 833 if ((r = sshsk_key_from_response(rks[i]->alg, 834 rks[i]->application, sk_flags, &rks[i]->key, &key)) != 0) 835 goto out; 836 if ((srk = calloc(1, sizeof(*srk))) == NULL) { 837 error_f("calloc failed"); 838 r = SSH_ERR_ALLOC_FAIL; 839 goto out; 840 } 841 srk->key = key; 842 key = NULL; /* transferred */ 843 if ((srk->user_id = calloc(1, rks[i]->user_id_len)) == NULL) { 844 error_f("calloc failed"); 845 r = SSH_ERR_ALLOC_FAIL; 846 goto out; 847 } 848 memcpy(srk->user_id, rks[i]->user_id, rks[i]->user_id_len); 849 srk->user_id_len = rks[i]->user_id_len; 850 if ((tmp = recallocarray(srks, nsrks, nsrks + 1, 851 sizeof(*tmp))) == NULL) { 852 error_f("recallocarray failed"); 853 r = SSH_ERR_ALLOC_FAIL; 854 goto out; 855 } 856 srks = tmp; 857 srks[nsrks++] = srk; 858 srk = NULL; 859 /* XXX synthesise comment */ 860 } 861 /* success */ 862 *srksp = srks; 863 *nsrksp = nsrks; 864 srks = NULL; 865 nsrks = 0; 866 r = 0; 867 out: 868 sshsk_free_options(opts); 869 sshsk_free(skp); 870 sshsk_free_sk_resident_keys(rks, nrks); 871 sshkey_free(key); 872 sshsk_free_resident_key(srk); 873 sshsk_free_resident_keys(srks, nsrks); 874 return r; 875 } 876 877 #endif /* ENABLE_SK */ 878