1 /* $OpenBSD: ssh-sk.c,v 1.41 2024/08/15 00:51:51 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 #include <openssl/evp.h> 36 #endif /* WITH_OPENSSL && OPENSSL_HAS_ECC */ 37 38 #include "log.h" 39 #include "misc.h" 40 #include "sshbuf.h" 41 #include "sshkey.h" 42 #include "ssherr.h" 43 #include "digest.h" 44 45 #include "ssh-sk.h" 46 #include "sk-api.h" 47 #include "crypto_api.h" 48 49 /* 50 * Almost every use of OpenSSL in this file is for ECDSA-NISTP256. 51 * This is strictly a larger hammer than necessary, but it reduces changes 52 * with upstream. 53 */ 54 #ifndef OPENSSL_HAS_ECC 55 # undef WITH_OPENSSL 56 #endif 57 58 struct sshsk_provider { 59 char *path; 60 void *dlhandle; 61 62 /* Return the version of the middleware API */ 63 uint32_t (*sk_api_version)(void); 64 65 /* Enroll a U2F key (private key generation) */ 66 int (*sk_enroll)(int alg, const uint8_t *challenge, 67 size_t challenge_len, const char *application, uint8_t flags, 68 const char *pin, struct sk_option **opts, 69 struct sk_enroll_response **enroll_response); 70 71 /* Sign a challenge */ 72 int (*sk_sign)(int alg, const uint8_t *message, size_t message_len, 73 const char *application, 74 const uint8_t *key_handle, size_t key_handle_len, 75 uint8_t flags, const char *pin, struct sk_option **opts, 76 struct sk_sign_response **sign_response); 77 78 /* Enumerate resident keys */ 79 int (*sk_load_resident_keys)(const char *pin, struct sk_option **opts, 80 struct sk_resident_key ***rks, size_t *nrks); 81 }; 82 83 /* Built-in version */ 84 int ssh_sk_enroll(int alg, const uint8_t *challenge, 85 size_t challenge_len, const char *application, uint8_t flags, 86 const char *pin, struct sk_option **opts, 87 struct sk_enroll_response **enroll_response); 88 int ssh_sk_sign(int alg, const uint8_t *message, size_t message_len, 89 const char *application, 90 const uint8_t *key_handle, size_t key_handle_len, 91 uint8_t flags, const char *pin, struct sk_option **opts, 92 struct sk_sign_response **sign_response); 93 int ssh_sk_load_resident_keys(const char *pin, struct sk_option **opts, 94 struct sk_resident_key ***rks, size_t *nrks); 95 96 static void 97 sshsk_free(struct sshsk_provider *p) 98 { 99 if (p == NULL) 100 return; 101 free(p->path); 102 if (p->dlhandle != NULL) 103 dlclose(p->dlhandle); 104 free(p); 105 } 106 107 static struct sshsk_provider * 108 sshsk_open(const char *path) 109 { 110 struct sshsk_provider *ret = NULL; 111 uint32_t version; 112 113 if (path == NULL || *path == '\0') { 114 error("No FIDO SecurityKeyProvider specified"); 115 return NULL; 116 } 117 if ((ret = calloc(1, sizeof(*ret))) == NULL) { 118 error_f("calloc failed"); 119 return NULL; 120 } 121 if ((ret->path = strdup(path)) == NULL) { 122 error_f("strdup failed"); 123 goto fail; 124 } 125 /* Skip the rest if we're using the linked in middleware */ 126 if (strcasecmp(ret->path, "internal") == 0) { 127 #ifdef ENABLE_SK_INTERNAL 128 ret->sk_enroll = ssh_sk_enroll; 129 ret->sk_sign = ssh_sk_sign; 130 ret->sk_load_resident_keys = ssh_sk_load_resident_keys; 131 return ret; 132 #else 133 error("internal security key support not enabled"); 134 goto fail; 135 #endif 136 } 137 if (lib_contains_symbol(path, "sk_api_version") != 0) { 138 error("provider %s is not an OpenSSH FIDO library", path); 139 goto fail; 140 } 141 if ((ret->dlhandle = dlopen(path, RTLD_NOW)) == NULL) 142 fatal("Provider \"%s\" dlopen failed: %s", path, dlerror()); 143 if ((ret->sk_api_version = dlsym(ret->dlhandle, 144 "sk_api_version")) == NULL) { 145 error("Provider \"%s\" dlsym(sk_api_version) failed: %s", 146 path, dlerror()); 147 goto fail; 148 } 149 version = ret->sk_api_version(); 150 debug_f("provider %s implements version 0x%08lx", ret->path, 151 (u_long)version); 152 if ((version & SSH_SK_VERSION_MAJOR_MASK) != SSH_SK_VERSION_MAJOR) { 153 error("Provider \"%s\" implements unsupported " 154 "version 0x%08lx (supported: 0x%08lx)", 155 path, (u_long)version, (u_long)SSH_SK_VERSION_MAJOR); 156 goto fail; 157 } 158 if ((ret->sk_enroll = dlsym(ret->dlhandle, "sk_enroll")) == NULL) { 159 error("Provider %s dlsym(sk_enroll) failed: %s", 160 path, dlerror()); 161 goto fail; 162 } 163 if ((ret->sk_sign = dlsym(ret->dlhandle, "sk_sign")) == NULL) { 164 error("Provider \"%s\" dlsym(sk_sign) failed: %s", 165 path, dlerror()); 166 goto fail; 167 } 168 if ((ret->sk_load_resident_keys = dlsym(ret->dlhandle, 169 "sk_load_resident_keys")) == NULL) { 170 error("Provider \"%s\" dlsym(sk_load_resident_keys) " 171 "failed: %s", path, dlerror()); 172 goto fail; 173 } 174 /* success */ 175 return ret; 176 fail: 177 sshsk_free(ret); 178 return NULL; 179 } 180 181 static void 182 sshsk_free_enroll_response(struct sk_enroll_response *r) 183 { 184 if (r == NULL) 185 return; 186 freezero(r->key_handle, r->key_handle_len); 187 freezero(r->public_key, r->public_key_len); 188 freezero(r->signature, r->signature_len); 189 freezero(r->attestation_cert, r->attestation_cert_len); 190 freezero(r->authdata, r->authdata_len); 191 freezero(r, sizeof(*r)); 192 } 193 194 static void 195 sshsk_free_sign_response(struct sk_sign_response *r) 196 { 197 if (r == NULL) 198 return; 199 freezero(r->sig_r, r->sig_r_len); 200 freezero(r->sig_s, r->sig_s_len); 201 freezero(r, sizeof(*r)); 202 } 203 204 #ifdef WITH_OPENSSL 205 /* Assemble key from response */ 206 static int 207 sshsk_ecdsa_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 208 { 209 struct sshkey *key = NULL; 210 struct sshbuf *b = NULL; 211 EC_KEY *ecdsa = NULL; 212 EC_POINT *q = NULL; 213 const EC_GROUP *g = NULL; 214 int r; 215 216 *keyp = NULL; 217 if ((key = sshkey_new(KEY_ECDSA_SK)) == NULL) { 218 error_f("sshkey_new failed"); 219 r = SSH_ERR_ALLOC_FAIL; 220 goto out; 221 } 222 key->ecdsa_nid = NID_X9_62_prime256v1; 223 if ((ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL || 224 (g = EC_KEY_get0_group(ecdsa)) == NULL || 225 (q = EC_POINT_new(g)) == NULL || 226 (b = sshbuf_new()) == NULL) { 227 error_f("allocation failed"); 228 r = SSH_ERR_ALLOC_FAIL; 229 goto out; 230 } 231 if ((r = sshbuf_put_string(b, 232 resp->public_key, resp->public_key_len)) != 0) { 233 error_fr(r, "sshbuf_put_string"); 234 goto out; 235 } 236 if ((r = sshbuf_get_ec(b, q, g)) != 0) { 237 error_fr(r, "parse"); 238 r = SSH_ERR_INVALID_FORMAT; 239 goto out; 240 } 241 if (sshkey_ec_validate_public(g, q) != 0) { 242 error("Authenticator returned invalid ECDSA key"); 243 r = SSH_ERR_KEY_INVALID_EC_VALUE; 244 goto out; 245 } 246 if (EC_KEY_set_public_key(ecdsa, q) != 1) { 247 /* XXX assume it is a allocation error */ 248 error_f("allocation failed"); 249 r = SSH_ERR_ALLOC_FAIL; 250 goto out; 251 } 252 if ((key->pkey = EVP_PKEY_new()) == NULL) { 253 error_f("allocation failed"); 254 r = SSH_ERR_ALLOC_FAIL; 255 goto out; 256 } 257 if (EVP_PKEY_set1_EC_KEY(key->pkey, ecdsa) != 1) { 258 error_f("Assigning EC_KEY failed"); 259 r = SSH_ERR_LIBCRYPTO_ERROR; 260 goto out; 261 } 262 /* success */ 263 *keyp = key; 264 key = NULL; /* transferred */ 265 r = 0; 266 out: 267 sshkey_free(key); 268 sshbuf_free(b); 269 EC_KEY_free(ecdsa); 270 EC_POINT_free(q); 271 return r; 272 } 273 #endif /* WITH_OPENSSL */ 274 275 static int 276 sshsk_ed25519_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 277 { 278 struct sshkey *key = NULL; 279 int r; 280 281 *keyp = NULL; 282 if (resp->public_key_len != ED25519_PK_SZ) { 283 error_f("invalid size: %zu", resp->public_key_len); 284 r = SSH_ERR_INVALID_FORMAT; 285 goto out; 286 } 287 if ((key = sshkey_new(KEY_ED25519_SK)) == NULL) { 288 error_f("sshkey_new failed"); 289 r = SSH_ERR_ALLOC_FAIL; 290 goto out; 291 } 292 if ((key->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) { 293 error_f("malloc failed"); 294 r = SSH_ERR_ALLOC_FAIL; 295 goto out; 296 } 297 memcpy(key->ed25519_pk, resp->public_key, ED25519_PK_SZ); 298 /* success */ 299 *keyp = key; 300 key = NULL; /* transferred */ 301 r = 0; 302 out: 303 sshkey_free(key); 304 return r; 305 } 306 307 static int 308 sshsk_key_from_response(int alg, const char *application, uint8_t flags, 309 struct sk_enroll_response *resp, struct sshkey **keyp) 310 { 311 struct sshkey *key = NULL; 312 int r = SSH_ERR_INTERNAL_ERROR; 313 314 *keyp = NULL; 315 316 /* Check response validity */ 317 if (resp->public_key == NULL || resp->key_handle == NULL) { 318 error_f("sk_enroll response invalid"); 319 r = SSH_ERR_INVALID_FORMAT; 320 goto out; 321 } 322 switch (alg) { 323 #ifdef WITH_OPENSSL 324 case SSH_SK_ECDSA: 325 if ((r = sshsk_ecdsa_assemble(resp, &key)) != 0) 326 goto out; 327 break; 328 #endif /* WITH_OPENSSL */ 329 case SSH_SK_ED25519: 330 if ((r = sshsk_ed25519_assemble(resp, &key)) != 0) 331 goto out; 332 break; 333 default: 334 error_f("unsupported algorithm %d", alg); 335 r = SSH_ERR_INVALID_ARGUMENT; 336 goto out; 337 } 338 key->sk_flags = flags; 339 if ((key->sk_key_handle = sshbuf_new()) == NULL || 340 (key->sk_reserved = sshbuf_new()) == NULL) { 341 error_f("allocation failed"); 342 r = SSH_ERR_ALLOC_FAIL; 343 goto out; 344 } 345 if ((key->sk_application = strdup(application)) == NULL) { 346 error_f("strdup application failed"); 347 r = SSH_ERR_ALLOC_FAIL; 348 goto out; 349 } 350 if ((r = sshbuf_put(key->sk_key_handle, resp->key_handle, 351 resp->key_handle_len)) != 0) { 352 error_fr(r, "put key handle"); 353 goto out; 354 } 355 /* success */ 356 r = 0; 357 *keyp = key; 358 key = NULL; 359 out: 360 sshkey_free(key); 361 return r; 362 } 363 364 static int 365 skerr_to_ssherr(int skerr) 366 { 367 switch (skerr) { 368 case SSH_SK_ERR_UNSUPPORTED: 369 return SSH_ERR_FEATURE_UNSUPPORTED; 370 case SSH_SK_ERR_PIN_REQUIRED: 371 return SSH_ERR_KEY_WRONG_PASSPHRASE; 372 case SSH_SK_ERR_DEVICE_NOT_FOUND: 373 return SSH_ERR_DEVICE_NOT_FOUND; 374 case SSH_SK_ERR_CREDENTIAL_EXISTS: 375 return SSH_ERR_KEY_BAD_PERMISSIONS; 376 case SSH_SK_ERR_GENERAL: 377 default: 378 return SSH_ERR_INVALID_FORMAT; 379 } 380 } 381 382 static void 383 sshsk_free_options(struct sk_option **opts) 384 { 385 size_t i; 386 387 if (opts == NULL) 388 return; 389 for (i = 0; opts[i] != NULL; i++) { 390 free(opts[i]->name); 391 free(opts[i]->value); 392 free(opts[i]); 393 } 394 free(opts); 395 } 396 397 static int 398 sshsk_add_option(struct sk_option ***optsp, size_t *noptsp, 399 const char *name, const char *value, uint8_t required) 400 { 401 struct sk_option **opts = *optsp; 402 size_t nopts = *noptsp; 403 404 if ((opts = recallocarray(opts, nopts, nopts + 2, /* extra for NULL */ 405 sizeof(*opts))) == NULL) { 406 error_f("array alloc failed"); 407 return SSH_ERR_ALLOC_FAIL; 408 } 409 *optsp = opts; 410 *noptsp = nopts + 1; 411 if ((opts[nopts] = calloc(1, sizeof(**opts))) == NULL) { 412 error_f("alloc failed"); 413 return SSH_ERR_ALLOC_FAIL; 414 } 415 if ((opts[nopts]->name = strdup(name)) == NULL || 416 (opts[nopts]->value = strdup(value)) == NULL) { 417 error_f("alloc failed"); 418 return SSH_ERR_ALLOC_FAIL; 419 } 420 opts[nopts]->required = required; 421 return 0; 422 } 423 424 static int 425 make_options(const char *device, const char *user_id, 426 struct sk_option ***optsp) 427 { 428 struct sk_option **opts = NULL; 429 size_t nopts = 0; 430 int r, ret = SSH_ERR_INTERNAL_ERROR; 431 432 if (device != NULL && 433 (r = sshsk_add_option(&opts, &nopts, "device", device, 0)) != 0) { 434 ret = r; 435 goto out; 436 } 437 if (user_id != NULL && 438 (r = sshsk_add_option(&opts, &nopts, "user", user_id, 0)) != 0) { 439 ret = r; 440 goto out; 441 } 442 /* success */ 443 *optsp = opts; 444 opts = NULL; 445 nopts = 0; 446 ret = 0; 447 out: 448 sshsk_free_options(opts); 449 return ret; 450 } 451 452 453 static int 454 fill_attestation_blob(const struct sk_enroll_response *resp, 455 struct sshbuf *attest) 456 { 457 int r; 458 459 if (attest == NULL) 460 return 0; /* nothing to do */ 461 if ((r = sshbuf_put_cstring(attest, "ssh-sk-attest-v01")) != 0 || 462 (r = sshbuf_put_string(attest, 463 resp->attestation_cert, resp->attestation_cert_len)) != 0 || 464 (r = sshbuf_put_string(attest, 465 resp->signature, resp->signature_len)) != 0 || 466 (r = sshbuf_put_string(attest, 467 resp->authdata, resp->authdata_len)) != 0 || 468 (r = sshbuf_put_u32(attest, 0)) != 0 || /* resvd flags */ 469 (r = sshbuf_put_string(attest, NULL, 0)) != 0 /* resvd */) { 470 error_fr(r, "compose"); 471 return r; 472 } 473 /* success */ 474 return 0; 475 } 476 477 int 478 sshsk_enroll(int type, const char *provider_path, const char *device, 479 const char *application, const char *userid, uint8_t flags, 480 const char *pin, struct sshbuf *challenge_buf, 481 struct sshkey **keyp, struct sshbuf *attest) 482 { 483 struct sshsk_provider *skp = NULL; 484 struct sshkey *key = NULL; 485 u_char randchall[32]; 486 const u_char *challenge; 487 size_t challenge_len; 488 struct sk_enroll_response *resp = NULL; 489 struct sk_option **opts = NULL; 490 int r = SSH_ERR_INTERNAL_ERROR; 491 int alg; 492 493 debug_f("provider \"%s\", device \"%s\", application \"%s\", " 494 "userid \"%s\", flags 0x%02x, challenge len %zu%s", 495 provider_path, device, application, userid, flags, 496 challenge_buf == NULL ? 0 : sshbuf_len(challenge_buf), 497 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 498 499 *keyp = NULL; 500 if (attest) 501 sshbuf_reset(attest); 502 503 if ((r = make_options(device, userid, &opts)) != 0) 504 goto out; 505 506 switch (type) { 507 #ifdef WITH_OPENSSL 508 case KEY_ECDSA_SK: 509 alg = SSH_SK_ECDSA; 510 break; 511 #endif /* WITH_OPENSSL */ 512 case KEY_ED25519_SK: 513 alg = SSH_SK_ED25519; 514 break; 515 default: 516 error_f("unsupported key type"); 517 r = SSH_ERR_INVALID_ARGUMENT; 518 goto out; 519 } 520 if (provider_path == NULL) { 521 error_f("missing provider"); 522 r = SSH_ERR_INVALID_ARGUMENT; 523 goto out; 524 } 525 if (application == NULL || *application == '\0') { 526 error_f("missing application"); 527 r = SSH_ERR_INVALID_ARGUMENT; 528 goto out; 529 } 530 if (challenge_buf == NULL) { 531 debug_f("using random challenge"); 532 arc4random_buf(randchall, sizeof(randchall)); 533 challenge = randchall; 534 challenge_len = sizeof(randchall); 535 } else if (sshbuf_len(challenge_buf) == 0) { 536 error("Missing enrollment challenge"); 537 r = SSH_ERR_INVALID_ARGUMENT; 538 goto out; 539 } else { 540 challenge = sshbuf_ptr(challenge_buf); 541 challenge_len = sshbuf_len(challenge_buf); 542 debug3_f("using explicit challenge len=%zd", challenge_len); 543 } 544 if ((skp = sshsk_open(provider_path)) == NULL) { 545 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 546 goto out; 547 } 548 /* XXX validate flags? */ 549 /* enroll key */ 550 if ((r = skp->sk_enroll(alg, challenge, challenge_len, application, 551 flags, pin, opts, &resp)) != 0) { 552 debug_f("provider \"%s\" failure %d", provider_path, r); 553 r = skerr_to_ssherr(r); 554 goto out; 555 } 556 557 if ((r = sshsk_key_from_response(alg, application, resp->flags, 558 resp, &key)) != 0) 559 goto out; 560 561 /* Optionally fill in the attestation information */ 562 if ((r = fill_attestation_blob(resp, attest)) != 0) 563 goto out; 564 565 /* success */ 566 *keyp = key; 567 key = NULL; /* transferred */ 568 r = 0; 569 out: 570 sshsk_free_options(opts); 571 sshsk_free(skp); 572 sshkey_free(key); 573 sshsk_free_enroll_response(resp); 574 explicit_bzero(randchall, sizeof(randchall)); 575 return r; 576 } 577 578 #ifdef WITH_OPENSSL 579 static int 580 sshsk_ecdsa_sig(struct sk_sign_response *resp, struct sshbuf *sig) 581 { 582 struct sshbuf *inner_sig = NULL; 583 int r = SSH_ERR_INTERNAL_ERROR; 584 585 /* Check response validity */ 586 if (resp->sig_r == NULL || resp->sig_s == NULL) { 587 error_f("sk_sign response invalid"); 588 r = SSH_ERR_INVALID_FORMAT; 589 goto out; 590 } 591 if ((inner_sig = sshbuf_new()) == NULL) { 592 r = SSH_ERR_ALLOC_FAIL; 593 goto out; 594 } 595 /* Prepare and append inner signature object */ 596 if ((r = sshbuf_put_bignum2_bytes(inner_sig, 597 resp->sig_r, resp->sig_r_len)) != 0 || 598 (r = sshbuf_put_bignum2_bytes(inner_sig, 599 resp->sig_s, resp->sig_s_len)) != 0) { 600 error_fr(r, "compose inner"); 601 goto out; 602 } 603 if ((r = sshbuf_put_stringb(sig, inner_sig)) != 0 || 604 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 605 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 606 error_fr(r, "compose"); 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 fprintf(stderr, "%s: sig_s:\n", __func__); 613 sshbuf_dump_data(resp->sig_s, resp->sig_s_len, stderr); 614 fprintf(stderr, "%s: inner:\n", __func__); 615 sshbuf_dump(inner_sig, stderr); 616 #endif 617 r = 0; 618 out: 619 sshbuf_free(inner_sig); 620 return r; 621 } 622 #endif /* WITH_OPENSSL */ 623 624 static int 625 sshsk_ed25519_sig(struct sk_sign_response *resp, struct sshbuf *sig) 626 { 627 int r = SSH_ERR_INTERNAL_ERROR; 628 629 /* Check response validity */ 630 if (resp->sig_r == NULL) { 631 error_f("sk_sign response invalid"); 632 r = SSH_ERR_INVALID_FORMAT; 633 goto out; 634 } 635 if ((r = sshbuf_put_string(sig, 636 resp->sig_r, resp->sig_r_len)) != 0 || 637 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 638 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 639 error_fr(r, "compose"); 640 goto out; 641 } 642 #ifdef DEBUG_SK 643 fprintf(stderr, "%s: sig_r:\n", __func__); 644 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 645 #endif 646 r = 0; 647 out: 648 return r; 649 } 650 651 int 652 sshsk_sign(const char *provider_path, struct sshkey *key, 653 u_char **sigp, size_t *lenp, const u_char *data, size_t datalen, 654 u_int compat, const char *pin) 655 { 656 struct sshsk_provider *skp = NULL; 657 int r = SSH_ERR_INTERNAL_ERROR; 658 int type, alg; 659 struct sk_sign_response *resp = NULL; 660 struct sshbuf *inner_sig = NULL, *sig = NULL; 661 struct sk_option **opts = NULL; 662 663 debug_f("provider \"%s\", key %s, flags 0x%02x%s", 664 provider_path, sshkey_type(key), key->sk_flags, 665 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 666 667 if (sigp != NULL) 668 *sigp = NULL; 669 if (lenp != NULL) 670 *lenp = 0; 671 type = sshkey_type_plain(key->type); 672 switch (type) { 673 #ifdef WITH_OPENSSL 674 case KEY_ECDSA_SK: 675 alg = SSH_SK_ECDSA; 676 break; 677 #endif /* WITH_OPENSSL */ 678 case KEY_ED25519_SK: 679 alg = SSH_SK_ED25519; 680 break; 681 default: 682 return SSH_ERR_INVALID_ARGUMENT; 683 } 684 if (provider_path == NULL || 685 key->sk_key_handle == NULL || 686 key->sk_application == NULL || *key->sk_application == '\0') { 687 r = SSH_ERR_INVALID_ARGUMENT; 688 goto out; 689 } 690 if ((skp = sshsk_open(provider_path)) == NULL) { 691 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 692 goto out; 693 } 694 #ifdef DEBUG_SK 695 fprintf(stderr, "%s: sk_flags = 0x%02x, sk_application = \"%s\"\n", 696 __func__, key->sk_flags, key->sk_application); 697 fprintf(stderr, "%s: sk_key_handle:\n", __func__); 698 sshbuf_dump(key->sk_key_handle, stderr); 699 #endif 700 if ((r = skp->sk_sign(alg, data, datalen, key->sk_application, 701 sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle), 702 key->sk_flags, pin, opts, &resp)) != 0) { 703 debug_f("sk_sign failed with code %d", r); 704 r = skerr_to_ssherr(r); 705 goto out; 706 } 707 /* Assemble signature */ 708 if ((sig = sshbuf_new()) == NULL) { 709 r = SSH_ERR_ALLOC_FAIL; 710 goto out; 711 } 712 if ((r = sshbuf_put_cstring(sig, sshkey_ssh_name_plain(key))) != 0) { 713 error_fr(r, "compose outer"); 714 goto out; 715 } 716 switch (type) { 717 #ifdef WITH_OPENSSL 718 case KEY_ECDSA_SK: 719 if ((r = sshsk_ecdsa_sig(resp, sig)) != 0) 720 goto out; 721 break; 722 #endif /* WITH_OPENSSL */ 723 case KEY_ED25519_SK: 724 if ((r = sshsk_ed25519_sig(resp, sig)) != 0) 725 goto out; 726 break; 727 } 728 #ifdef DEBUG_SK 729 fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n", 730 __func__, resp->flags, resp->counter); 731 fprintf(stderr, "%s: data to sign:\n", __func__); 732 sshbuf_dump_data(data, datalen, stderr); 733 fprintf(stderr, "%s: sigbuf:\n", __func__); 734 sshbuf_dump(sig, stderr); 735 #endif 736 if (sigp != NULL) { 737 if ((*sigp = malloc(sshbuf_len(sig))) == NULL) { 738 r = SSH_ERR_ALLOC_FAIL; 739 goto out; 740 } 741 memcpy(*sigp, sshbuf_ptr(sig), sshbuf_len(sig)); 742 } 743 if (lenp != NULL) 744 *lenp = sshbuf_len(sig); 745 /* success */ 746 r = 0; 747 out: 748 sshsk_free_options(opts); 749 sshsk_free(skp); 750 sshsk_free_sign_response(resp); 751 sshbuf_free(sig); 752 sshbuf_free(inner_sig); 753 return r; 754 } 755 756 static void 757 sshsk_free_sk_resident_keys(struct sk_resident_key **rks, size_t nrks) 758 { 759 size_t i; 760 761 if (nrks == 0 || rks == NULL) 762 return; 763 for (i = 0; i < nrks; i++) { 764 free(rks[i]->application); 765 freezero(rks[i]->user_id, rks[i]->user_id_len); 766 freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len); 767 freezero(rks[i]->key.public_key, rks[i]->key.public_key_len); 768 freezero(rks[i]->key.signature, rks[i]->key.signature_len); 769 freezero(rks[i]->key.attestation_cert, 770 rks[i]->key.attestation_cert_len); 771 freezero(rks[i], sizeof(**rks)); 772 } 773 free(rks); 774 } 775 776 static void 777 sshsk_free_resident_key(struct sshsk_resident_key *srk) 778 { 779 if (srk == NULL) 780 return; 781 sshkey_free(srk->key); 782 freezero(srk->user_id, srk->user_id_len); 783 free(srk); 784 } 785 786 787 void 788 sshsk_free_resident_keys(struct sshsk_resident_key **srks, size_t nsrks) 789 { 790 size_t i; 791 792 if (srks == NULL || nsrks == 0) 793 return; 794 795 for (i = 0; i < nsrks; i++) 796 sshsk_free_resident_key(srks[i]); 797 free(srks); 798 } 799 800 int 801 sshsk_load_resident(const char *provider_path, const char *device, 802 const char *pin, u_int flags, struct sshsk_resident_key ***srksp, 803 size_t *nsrksp) 804 { 805 struct sshsk_provider *skp = NULL; 806 int r = SSH_ERR_INTERNAL_ERROR; 807 struct sk_resident_key **rks = NULL; 808 size_t i, nrks = 0, nsrks = 0; 809 struct sshkey *key = NULL; 810 struct sshsk_resident_key *srk = NULL, **srks = NULL, **tmp; 811 uint8_t sk_flags; 812 struct sk_option **opts = NULL; 813 814 debug_f("provider \"%s\"%s", provider_path, 815 (pin != NULL && *pin != '\0') ? ", have-pin": ""); 816 817 if (srksp == NULL || nsrksp == NULL) 818 return SSH_ERR_INVALID_ARGUMENT; 819 *srksp = NULL; 820 *nsrksp = 0; 821 822 if ((r = make_options(device, NULL, &opts)) != 0) 823 goto out; 824 if ((skp = sshsk_open(provider_path)) == NULL) { 825 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 826 goto out; 827 } 828 if ((r = skp->sk_load_resident_keys(pin, opts, &rks, &nrks)) != 0) { 829 error("Provider \"%s\" returned failure %d", provider_path, r); 830 r = skerr_to_ssherr(r); 831 goto out; 832 } 833 for (i = 0; i < nrks; i++) { 834 debug3_f("rk %zu: slot %zu, alg %d, app \"%s\", uidlen %zu", 835 i, rks[i]->slot, rks[i]->alg, rks[i]->application, 836 rks[i]->user_id_len); 837 /* XXX need better filter here */ 838 if (strncmp(rks[i]->application, "ssh:", 4) != 0) 839 continue; 840 switch (rks[i]->alg) { 841 case SSH_SK_ECDSA: 842 case SSH_SK_ED25519: 843 break; 844 default: 845 continue; 846 } 847 sk_flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY; 848 if ((rks[i]->flags & SSH_SK_USER_VERIFICATION_REQD)) 849 sk_flags |= SSH_SK_USER_VERIFICATION_REQD; 850 if ((r = sshsk_key_from_response(rks[i]->alg, 851 rks[i]->application, sk_flags, &rks[i]->key, &key)) != 0) 852 goto out; 853 if ((srk = calloc(1, sizeof(*srk))) == NULL) { 854 error_f("calloc failed"); 855 r = SSH_ERR_ALLOC_FAIL; 856 goto out; 857 } 858 srk->key = key; 859 key = NULL; /* transferred */ 860 if ((srk->user_id = calloc(1, rks[i]->user_id_len)) == NULL) { 861 error_f("calloc failed"); 862 r = SSH_ERR_ALLOC_FAIL; 863 goto out; 864 } 865 memcpy(srk->user_id, rks[i]->user_id, rks[i]->user_id_len); 866 srk->user_id_len = rks[i]->user_id_len; 867 if ((tmp = recallocarray(srks, nsrks, nsrks + 1, 868 sizeof(*tmp))) == NULL) { 869 error_f("recallocarray failed"); 870 r = SSH_ERR_ALLOC_FAIL; 871 goto out; 872 } 873 srks = tmp; 874 srks[nsrks++] = srk; 875 srk = NULL; 876 /* XXX synthesise comment */ 877 } 878 /* success */ 879 *srksp = srks; 880 *nsrksp = nsrks; 881 srks = NULL; 882 nsrks = 0; 883 r = 0; 884 out: 885 sshsk_free_options(opts); 886 sshsk_free(skp); 887 sshsk_free_sk_resident_keys(rks, nrks); 888 sshkey_free(key); 889 sshsk_free_resident_key(srk); 890 sshsk_free_resident_keys(srks, nsrks); 891 return r; 892 } 893 894 #endif /* ENABLE_SK */ 895