1 /* $OpenBSD: ssh-sk.c,v 1.40 2023/07/19 14:02:27 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 (lib_contains_symbol(path, "sk_api_version") != 0) { 137 error("provider %s is not an OpenSSH FIDO library", path); 138 goto fail; 139 } 140 if ((ret->dlhandle = dlopen(path, RTLD_NOW)) == NULL) 141 fatal("Provider \"%s\" dlopen failed: %s", path, dlerror()); 142 if ((ret->sk_api_version = dlsym(ret->dlhandle, 143 "sk_api_version")) == NULL) { 144 error("Provider \"%s\" dlsym(sk_api_version) failed: %s", 145 path, dlerror()); 146 goto fail; 147 } 148 version = ret->sk_api_version(); 149 debug_f("provider %s implements version 0x%08lx", ret->path, 150 (u_long)version); 151 if ((version & SSH_SK_VERSION_MAJOR_MASK) != SSH_SK_VERSION_MAJOR) { 152 error("Provider \"%s\" implements unsupported " 153 "version 0x%08lx (supported: 0x%08lx)", 154 path, (u_long)version, (u_long)SSH_SK_VERSION_MAJOR); 155 goto fail; 156 } 157 if ((ret->sk_enroll = dlsym(ret->dlhandle, "sk_enroll")) == NULL) { 158 error("Provider %s dlsym(sk_enroll) failed: %s", 159 path, dlerror()); 160 goto fail; 161 } 162 if ((ret->sk_sign = dlsym(ret->dlhandle, "sk_sign")) == NULL) { 163 error("Provider \"%s\" dlsym(sk_sign) failed: %s", 164 path, dlerror()); 165 goto fail; 166 } 167 if ((ret->sk_load_resident_keys = dlsym(ret->dlhandle, 168 "sk_load_resident_keys")) == NULL) { 169 error("Provider \"%s\" dlsym(sk_load_resident_keys) " 170 "failed: %s", path, dlerror()); 171 goto fail; 172 } 173 /* success */ 174 return ret; 175 fail: 176 sshsk_free(ret); 177 return NULL; 178 } 179 180 static void 181 sshsk_free_enroll_response(struct sk_enroll_response *r) 182 { 183 if (r == NULL) 184 return; 185 freezero(r->key_handle, r->key_handle_len); 186 freezero(r->public_key, r->public_key_len); 187 freezero(r->signature, r->signature_len); 188 freezero(r->attestation_cert, r->attestation_cert_len); 189 freezero(r->authdata, r->authdata_len); 190 freezero(r, sizeof(*r)); 191 } 192 193 static void 194 sshsk_free_sign_response(struct sk_sign_response *r) 195 { 196 if (r == NULL) 197 return; 198 freezero(r->sig_r, r->sig_r_len); 199 freezero(r->sig_s, r->sig_s_len); 200 freezero(r, sizeof(*r)); 201 } 202 203 #ifdef WITH_OPENSSL 204 /* Assemble key from response */ 205 static int 206 sshsk_ecdsa_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 207 { 208 struct sshkey *key = NULL; 209 struct sshbuf *b = NULL; 210 EC_POINT *q = NULL; 211 int r; 212 213 *keyp = NULL; 214 if ((key = sshkey_new(KEY_ECDSA_SK)) == NULL) { 215 error_f("sshkey_new failed"); 216 r = SSH_ERR_ALLOC_FAIL; 217 goto out; 218 } 219 key->ecdsa_nid = NID_X9_62_prime256v1; 220 if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL || 221 (q = EC_POINT_new(EC_KEY_get0_group(key->ecdsa))) == NULL || 222 (b = sshbuf_new()) == NULL) { 223 error_f("allocation failed"); 224 r = SSH_ERR_ALLOC_FAIL; 225 goto out; 226 } 227 if ((r = sshbuf_put_string(b, 228 resp->public_key, resp->public_key_len)) != 0) { 229 error_fr(r, "sshbuf_put_string"); 230 goto out; 231 } 232 if ((r = sshbuf_get_ec(b, q, EC_KEY_get0_group(key->ecdsa))) != 0) { 233 error_fr(r, "parse"); 234 r = SSH_ERR_INVALID_FORMAT; 235 goto out; 236 } 237 if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa), q) != 0) { 238 error("Authenticator returned invalid ECDSA key"); 239 r = SSH_ERR_KEY_INVALID_EC_VALUE; 240 goto out; 241 } 242 if (EC_KEY_set_public_key(key->ecdsa, q) != 1) { 243 /* XXX assume it is a allocation error */ 244 error_f("allocation failed"); 245 r = SSH_ERR_ALLOC_FAIL; 246 goto out; 247 } 248 /* success */ 249 *keyp = key; 250 key = NULL; /* transferred */ 251 r = 0; 252 out: 253 EC_POINT_free(q); 254 sshkey_free(key); 255 sshbuf_free(b); 256 return r; 257 } 258 #endif /* WITH_OPENSSL */ 259 260 static int 261 sshsk_ed25519_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 262 { 263 struct sshkey *key = NULL; 264 int r; 265 266 *keyp = NULL; 267 if (resp->public_key_len != ED25519_PK_SZ) { 268 error_f("invalid size: %zu", resp->public_key_len); 269 r = SSH_ERR_INVALID_FORMAT; 270 goto out; 271 } 272 if ((key = sshkey_new(KEY_ED25519_SK)) == NULL) { 273 error_f("sshkey_new failed"); 274 r = SSH_ERR_ALLOC_FAIL; 275 goto out; 276 } 277 if ((key->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) { 278 error_f("malloc failed"); 279 r = SSH_ERR_ALLOC_FAIL; 280 goto out; 281 } 282 memcpy(key->ed25519_pk, resp->public_key, ED25519_PK_SZ); 283 /* success */ 284 *keyp = key; 285 key = NULL; /* transferred */ 286 r = 0; 287 out: 288 sshkey_free(key); 289 return r; 290 } 291 292 static int 293 sshsk_key_from_response(int alg, const char *application, uint8_t flags, 294 struct sk_enroll_response *resp, struct sshkey **keyp) 295 { 296 struct sshkey *key = NULL; 297 int r = SSH_ERR_INTERNAL_ERROR; 298 299 *keyp = NULL; 300 301 /* Check response validity */ 302 if (resp->public_key == NULL || resp->key_handle == NULL) { 303 error_f("sk_enroll response invalid"); 304 r = SSH_ERR_INVALID_FORMAT; 305 goto out; 306 } 307 switch (alg) { 308 #ifdef WITH_OPENSSL 309 case SSH_SK_ECDSA: 310 if ((r = sshsk_ecdsa_assemble(resp, &key)) != 0) 311 goto out; 312 break; 313 #endif /* WITH_OPENSSL */ 314 case SSH_SK_ED25519: 315 if ((r = sshsk_ed25519_assemble(resp, &key)) != 0) 316 goto out; 317 break; 318 default: 319 error_f("unsupported algorithm %d", alg); 320 r = SSH_ERR_INVALID_ARGUMENT; 321 goto out; 322 } 323 key->sk_flags = flags; 324 if ((key->sk_key_handle = sshbuf_new()) == NULL || 325 (key->sk_reserved = sshbuf_new()) == NULL) { 326 error_f("allocation failed"); 327 r = SSH_ERR_ALLOC_FAIL; 328 goto out; 329 } 330 if ((key->sk_application = strdup(application)) == NULL) { 331 error_f("strdup application failed"); 332 r = SSH_ERR_ALLOC_FAIL; 333 goto out; 334 } 335 if ((r = sshbuf_put(key->sk_key_handle, resp->key_handle, 336 resp->key_handle_len)) != 0) { 337 error_fr(r, "put key handle"); 338 goto out; 339 } 340 /* success */ 341 r = 0; 342 *keyp = key; 343 key = NULL; 344 out: 345 sshkey_free(key); 346 return r; 347 } 348 349 static int 350 skerr_to_ssherr(int skerr) 351 { 352 switch (skerr) { 353 case SSH_SK_ERR_UNSUPPORTED: 354 return SSH_ERR_FEATURE_UNSUPPORTED; 355 case SSH_SK_ERR_PIN_REQUIRED: 356 return SSH_ERR_KEY_WRONG_PASSPHRASE; 357 case SSH_SK_ERR_DEVICE_NOT_FOUND: 358 return SSH_ERR_DEVICE_NOT_FOUND; 359 case SSH_SK_ERR_CREDENTIAL_EXISTS: 360 return SSH_ERR_KEY_BAD_PERMISSIONS; 361 case SSH_SK_ERR_GENERAL: 362 default: 363 return SSH_ERR_INVALID_FORMAT; 364 } 365 } 366 367 static void 368 sshsk_free_options(struct sk_option **opts) 369 { 370 size_t i; 371 372 if (opts == NULL) 373 return; 374 for (i = 0; opts[i] != NULL; i++) { 375 free(opts[i]->name); 376 free(opts[i]->value); 377 free(opts[i]); 378 } 379 free(opts); 380 } 381 382 static int 383 sshsk_add_option(struct sk_option ***optsp, size_t *noptsp, 384 const char *name, const char *value, uint8_t required) 385 { 386 struct sk_option **opts = *optsp; 387 size_t nopts = *noptsp; 388 389 if ((opts = recallocarray(opts, nopts, nopts + 2, /* extra for NULL */ 390 sizeof(*opts))) == NULL) { 391 error_f("array alloc failed"); 392 return SSH_ERR_ALLOC_FAIL; 393 } 394 *optsp = opts; 395 *noptsp = nopts + 1; 396 if ((opts[nopts] = calloc(1, sizeof(**opts))) == NULL) { 397 error_f("alloc failed"); 398 return SSH_ERR_ALLOC_FAIL; 399 } 400 if ((opts[nopts]->name = strdup(name)) == NULL || 401 (opts[nopts]->value = strdup(value)) == NULL) { 402 error_f("alloc failed"); 403 return SSH_ERR_ALLOC_FAIL; 404 } 405 opts[nopts]->required = required; 406 return 0; 407 } 408 409 static int 410 make_options(const char *device, const char *user_id, 411 struct sk_option ***optsp) 412 { 413 struct sk_option **opts = NULL; 414 size_t nopts = 0; 415 int r, ret = SSH_ERR_INTERNAL_ERROR; 416 417 if (device != NULL && 418 (r = sshsk_add_option(&opts, &nopts, "device", device, 0)) != 0) { 419 ret = r; 420 goto out; 421 } 422 if (user_id != NULL && 423 (r = sshsk_add_option(&opts, &nopts, "user", user_id, 0)) != 0) { 424 ret = r; 425 goto out; 426 } 427 /* success */ 428 *optsp = opts; 429 opts = NULL; 430 nopts = 0; 431 ret = 0; 432 out: 433 sshsk_free_options(opts); 434 return ret; 435 } 436 437 438 static int 439 fill_attestation_blob(const struct sk_enroll_response *resp, 440 struct sshbuf *attest) 441 { 442 int r; 443 444 if (attest == NULL) 445 return 0; /* nothing to do */ 446 if ((r = sshbuf_put_cstring(attest, "ssh-sk-attest-v01")) != 0 || 447 (r = sshbuf_put_string(attest, 448 resp->attestation_cert, resp->attestation_cert_len)) != 0 || 449 (r = sshbuf_put_string(attest, 450 resp->signature, resp->signature_len)) != 0 || 451 (r = sshbuf_put_string(attest, 452 resp->authdata, resp->authdata_len)) != 0 || 453 (r = sshbuf_put_u32(attest, 0)) != 0 || /* resvd flags */ 454 (r = sshbuf_put_string(attest, NULL, 0)) != 0 /* resvd */) { 455 error_fr(r, "compose"); 456 return r; 457 } 458 /* success */ 459 return 0; 460 } 461 462 int 463 sshsk_enroll(int type, const char *provider_path, const char *device, 464 const char *application, const char *userid, uint8_t flags, 465 const char *pin, struct sshbuf *challenge_buf, 466 struct sshkey **keyp, struct sshbuf *attest) 467 { 468 struct sshsk_provider *skp = NULL; 469 struct sshkey *key = NULL; 470 u_char randchall[32]; 471 const u_char *challenge; 472 size_t challenge_len; 473 struct sk_enroll_response *resp = NULL; 474 struct sk_option **opts = NULL; 475 int r = SSH_ERR_INTERNAL_ERROR; 476 int alg; 477 478 debug_f("provider \"%s\", device \"%s\", application \"%s\", " 479 "userid \"%s\", flags 0x%02x, challenge len %zu%s", 480 provider_path, device, application, userid, flags, 481 challenge_buf == NULL ? 0 : sshbuf_len(challenge_buf), 482 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 483 484 *keyp = NULL; 485 if (attest) 486 sshbuf_reset(attest); 487 488 if ((r = make_options(device, userid, &opts)) != 0) 489 goto out; 490 491 switch (type) { 492 #ifdef WITH_OPENSSL 493 case KEY_ECDSA_SK: 494 alg = SSH_SK_ECDSA; 495 break; 496 #endif /* WITH_OPENSSL */ 497 case KEY_ED25519_SK: 498 alg = SSH_SK_ED25519; 499 break; 500 default: 501 error_f("unsupported key type"); 502 r = SSH_ERR_INVALID_ARGUMENT; 503 goto out; 504 } 505 if (provider_path == NULL) { 506 error_f("missing provider"); 507 r = SSH_ERR_INVALID_ARGUMENT; 508 goto out; 509 } 510 if (application == NULL || *application == '\0') { 511 error_f("missing application"); 512 r = SSH_ERR_INVALID_ARGUMENT; 513 goto out; 514 } 515 if (challenge_buf == NULL) { 516 debug_f("using random challenge"); 517 arc4random_buf(randchall, sizeof(randchall)); 518 challenge = randchall; 519 challenge_len = sizeof(randchall); 520 } else if (sshbuf_len(challenge_buf) == 0) { 521 error("Missing enrollment challenge"); 522 r = SSH_ERR_INVALID_ARGUMENT; 523 goto out; 524 } else { 525 challenge = sshbuf_ptr(challenge_buf); 526 challenge_len = sshbuf_len(challenge_buf); 527 debug3_f("using explicit challenge len=%zd", challenge_len); 528 } 529 if ((skp = sshsk_open(provider_path)) == NULL) { 530 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 531 goto out; 532 } 533 /* XXX validate flags? */ 534 /* enroll key */ 535 if ((r = skp->sk_enroll(alg, challenge, challenge_len, application, 536 flags, pin, opts, &resp)) != 0) { 537 debug_f("provider \"%s\" failure %d", provider_path, r); 538 r = skerr_to_ssherr(r); 539 goto out; 540 } 541 542 if ((r = sshsk_key_from_response(alg, application, resp->flags, 543 resp, &key)) != 0) 544 goto out; 545 546 /* Optionally fill in the attestation information */ 547 if ((r = fill_attestation_blob(resp, attest)) != 0) 548 goto out; 549 550 /* success */ 551 *keyp = key; 552 key = NULL; /* transferred */ 553 r = 0; 554 out: 555 sshsk_free_options(opts); 556 sshsk_free(skp); 557 sshkey_free(key); 558 sshsk_free_enroll_response(resp); 559 explicit_bzero(randchall, sizeof(randchall)); 560 return r; 561 } 562 563 #ifdef WITH_OPENSSL 564 static int 565 sshsk_ecdsa_sig(struct sk_sign_response *resp, struct sshbuf *sig) 566 { 567 struct sshbuf *inner_sig = NULL; 568 int r = SSH_ERR_INTERNAL_ERROR; 569 570 /* Check response validity */ 571 if (resp->sig_r == NULL || resp->sig_s == NULL) { 572 error_f("sk_sign response invalid"); 573 r = SSH_ERR_INVALID_FORMAT; 574 goto out; 575 } 576 if ((inner_sig = sshbuf_new()) == NULL) { 577 r = SSH_ERR_ALLOC_FAIL; 578 goto out; 579 } 580 /* Prepare and append inner signature object */ 581 if ((r = sshbuf_put_bignum2_bytes(inner_sig, 582 resp->sig_r, resp->sig_r_len)) != 0 || 583 (r = sshbuf_put_bignum2_bytes(inner_sig, 584 resp->sig_s, resp->sig_s_len)) != 0) { 585 error_fr(r, "compose inner"); 586 goto out; 587 } 588 if ((r = sshbuf_put_stringb(sig, inner_sig)) != 0 || 589 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 590 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 591 error_fr(r, "compose"); 592 goto out; 593 } 594 #ifdef DEBUG_SK 595 fprintf(stderr, "%s: sig_r:\n", __func__); 596 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 597 fprintf(stderr, "%s: sig_s:\n", __func__); 598 sshbuf_dump_data(resp->sig_s, resp->sig_s_len, stderr); 599 fprintf(stderr, "%s: inner:\n", __func__); 600 sshbuf_dump(inner_sig, stderr); 601 #endif 602 r = 0; 603 out: 604 sshbuf_free(inner_sig); 605 return r; 606 } 607 #endif /* WITH_OPENSSL */ 608 609 static int 610 sshsk_ed25519_sig(struct sk_sign_response *resp, struct sshbuf *sig) 611 { 612 int r = SSH_ERR_INTERNAL_ERROR; 613 614 /* Check response validity */ 615 if (resp->sig_r == NULL) { 616 error_f("sk_sign response invalid"); 617 r = SSH_ERR_INVALID_FORMAT; 618 goto out; 619 } 620 if ((r = sshbuf_put_string(sig, 621 resp->sig_r, resp->sig_r_len)) != 0 || 622 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 623 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 624 error_fr(r, "compose"); 625 goto out; 626 } 627 #ifdef DEBUG_SK 628 fprintf(stderr, "%s: sig_r:\n", __func__); 629 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 630 #endif 631 r = 0; 632 out: 633 return r; 634 } 635 636 int 637 sshsk_sign(const char *provider_path, struct sshkey *key, 638 u_char **sigp, size_t *lenp, const u_char *data, size_t datalen, 639 u_int compat, const char *pin) 640 { 641 struct sshsk_provider *skp = NULL; 642 int r = SSH_ERR_INTERNAL_ERROR; 643 int type, alg; 644 struct sk_sign_response *resp = NULL; 645 struct sshbuf *inner_sig = NULL, *sig = NULL; 646 struct sk_option **opts = NULL; 647 648 debug_f("provider \"%s\", key %s, flags 0x%02x%s", 649 provider_path, sshkey_type(key), key->sk_flags, 650 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 651 652 if (sigp != NULL) 653 *sigp = NULL; 654 if (lenp != NULL) 655 *lenp = 0; 656 type = sshkey_type_plain(key->type); 657 switch (type) { 658 #ifdef WITH_OPENSSL 659 case KEY_ECDSA_SK: 660 alg = SSH_SK_ECDSA; 661 break; 662 #endif /* WITH_OPENSSL */ 663 case KEY_ED25519_SK: 664 alg = SSH_SK_ED25519; 665 break; 666 default: 667 return SSH_ERR_INVALID_ARGUMENT; 668 } 669 if (provider_path == NULL || 670 key->sk_key_handle == NULL || 671 key->sk_application == NULL || *key->sk_application == '\0') { 672 r = SSH_ERR_INVALID_ARGUMENT; 673 goto out; 674 } 675 if ((skp = sshsk_open(provider_path)) == NULL) { 676 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 677 goto out; 678 } 679 #ifdef DEBUG_SK 680 fprintf(stderr, "%s: sk_flags = 0x%02x, sk_application = \"%s\"\n", 681 __func__, key->sk_flags, key->sk_application); 682 fprintf(stderr, "%s: sk_key_handle:\n", __func__); 683 sshbuf_dump(key->sk_key_handle, stderr); 684 #endif 685 if ((r = skp->sk_sign(alg, data, datalen, key->sk_application, 686 sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle), 687 key->sk_flags, pin, opts, &resp)) != 0) { 688 debug_f("sk_sign failed with code %d", r); 689 r = skerr_to_ssherr(r); 690 goto out; 691 } 692 /* Assemble signature */ 693 if ((sig = sshbuf_new()) == NULL) { 694 r = SSH_ERR_ALLOC_FAIL; 695 goto out; 696 } 697 if ((r = sshbuf_put_cstring(sig, sshkey_ssh_name_plain(key))) != 0) { 698 error_fr(r, "compose outer"); 699 goto out; 700 } 701 switch (type) { 702 #ifdef WITH_OPENSSL 703 case KEY_ECDSA_SK: 704 if ((r = sshsk_ecdsa_sig(resp, sig)) != 0) 705 goto out; 706 break; 707 #endif /* WITH_OPENSSL */ 708 case KEY_ED25519_SK: 709 if ((r = sshsk_ed25519_sig(resp, sig)) != 0) 710 goto out; 711 break; 712 } 713 #ifdef DEBUG_SK 714 fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n", 715 __func__, resp->flags, resp->counter); 716 fprintf(stderr, "%s: data to sign:\n", __func__); 717 sshbuf_dump_data(data, datalen, stderr); 718 fprintf(stderr, "%s: sigbuf:\n", __func__); 719 sshbuf_dump(sig, stderr); 720 #endif 721 if (sigp != NULL) { 722 if ((*sigp = malloc(sshbuf_len(sig))) == NULL) { 723 r = SSH_ERR_ALLOC_FAIL; 724 goto out; 725 } 726 memcpy(*sigp, sshbuf_ptr(sig), sshbuf_len(sig)); 727 } 728 if (lenp != NULL) 729 *lenp = sshbuf_len(sig); 730 /* success */ 731 r = 0; 732 out: 733 sshsk_free_options(opts); 734 sshsk_free(skp); 735 sshsk_free_sign_response(resp); 736 sshbuf_free(sig); 737 sshbuf_free(inner_sig); 738 return r; 739 } 740 741 static void 742 sshsk_free_sk_resident_keys(struct sk_resident_key **rks, size_t nrks) 743 { 744 size_t i; 745 746 if (nrks == 0 || rks == NULL) 747 return; 748 for (i = 0; i < nrks; i++) { 749 free(rks[i]->application); 750 freezero(rks[i]->user_id, rks[i]->user_id_len); 751 freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len); 752 freezero(rks[i]->key.public_key, rks[i]->key.public_key_len); 753 freezero(rks[i]->key.signature, rks[i]->key.signature_len); 754 freezero(rks[i]->key.attestation_cert, 755 rks[i]->key.attestation_cert_len); 756 freezero(rks[i], sizeof(**rks)); 757 } 758 free(rks); 759 } 760 761 static void 762 sshsk_free_resident_key(struct sshsk_resident_key *srk) 763 { 764 if (srk == NULL) 765 return; 766 sshkey_free(srk->key); 767 freezero(srk->user_id, srk->user_id_len); 768 free(srk); 769 } 770 771 772 void 773 sshsk_free_resident_keys(struct sshsk_resident_key **srks, size_t nsrks) 774 { 775 size_t i; 776 777 if (srks == NULL || nsrks == 0) 778 return; 779 780 for (i = 0; i < nsrks; i++) 781 sshsk_free_resident_key(srks[i]); 782 free(srks); 783 } 784 785 int 786 sshsk_load_resident(const char *provider_path, const char *device, 787 const char *pin, u_int flags, struct sshsk_resident_key ***srksp, 788 size_t *nsrksp) 789 { 790 struct sshsk_provider *skp = NULL; 791 int r = SSH_ERR_INTERNAL_ERROR; 792 struct sk_resident_key **rks = NULL; 793 size_t i, nrks = 0, nsrks = 0; 794 struct sshkey *key = NULL; 795 struct sshsk_resident_key *srk = NULL, **srks = NULL, **tmp; 796 uint8_t sk_flags; 797 struct sk_option **opts = NULL; 798 799 debug_f("provider \"%s\"%s", provider_path, 800 (pin != NULL && *pin != '\0') ? ", have-pin": ""); 801 802 if (srksp == NULL || nsrksp == NULL) 803 return SSH_ERR_INVALID_ARGUMENT; 804 *srksp = NULL; 805 *nsrksp = 0; 806 807 if ((r = make_options(device, NULL, &opts)) != 0) 808 goto out; 809 if ((skp = sshsk_open(provider_path)) == NULL) { 810 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 811 goto out; 812 } 813 if ((r = skp->sk_load_resident_keys(pin, opts, &rks, &nrks)) != 0) { 814 error("Provider \"%s\" returned failure %d", provider_path, r); 815 r = skerr_to_ssherr(r); 816 goto out; 817 } 818 for (i = 0; i < nrks; i++) { 819 debug3_f("rk %zu: slot %zu, alg %d, app \"%s\", uidlen %zu", 820 i, rks[i]->slot, rks[i]->alg, rks[i]->application, 821 rks[i]->user_id_len); 822 /* XXX need better filter here */ 823 if (strncmp(rks[i]->application, "ssh:", 4) != 0) 824 continue; 825 switch (rks[i]->alg) { 826 case SSH_SK_ECDSA: 827 case SSH_SK_ED25519: 828 break; 829 default: 830 continue; 831 } 832 sk_flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY; 833 if ((rks[i]->flags & SSH_SK_USER_VERIFICATION_REQD)) 834 sk_flags |= SSH_SK_USER_VERIFICATION_REQD; 835 if ((r = sshsk_key_from_response(rks[i]->alg, 836 rks[i]->application, sk_flags, &rks[i]->key, &key)) != 0) 837 goto out; 838 if ((srk = calloc(1, sizeof(*srk))) == NULL) { 839 error_f("calloc failed"); 840 r = SSH_ERR_ALLOC_FAIL; 841 goto out; 842 } 843 srk->key = key; 844 key = NULL; /* transferred */ 845 if ((srk->user_id = calloc(1, rks[i]->user_id_len)) == NULL) { 846 error_f("calloc failed"); 847 r = SSH_ERR_ALLOC_FAIL; 848 goto out; 849 } 850 memcpy(srk->user_id, rks[i]->user_id, rks[i]->user_id_len); 851 srk->user_id_len = rks[i]->user_id_len; 852 if ((tmp = recallocarray(srks, nsrks, nsrks + 1, 853 sizeof(*tmp))) == NULL) { 854 error_f("recallocarray failed"); 855 r = SSH_ERR_ALLOC_FAIL; 856 goto out; 857 } 858 srks = tmp; 859 srks[nsrks++] = srk; 860 srk = NULL; 861 /* XXX synthesise comment */ 862 } 863 /* success */ 864 *srksp = srks; 865 *nsrksp = nsrks; 866 srks = NULL; 867 nsrks = 0; 868 r = 0; 869 out: 870 sshsk_free_options(opts); 871 sshsk_free(skp); 872 sshsk_free_sk_resident_keys(rks, nrks); 873 sshkey_free(key); 874 sshsk_free_resident_key(srk); 875 sshsk_free_resident_keys(srks, nsrks); 876 return r; 877 } 878 879 #endif /* ENABLE_SK */ 880