1 /* $OpenBSD: ssh-sk.c,v 1.38 2022/01/14 03:35:10 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 #else 131 error("internal security key support not enabled"); 132 #endif 133 return ret; 134 } 135 if ((ret->dlhandle = dlopen(path, RTLD_NOW)) == NULL) { 136 error("Provider \"%s\" dlopen failed: %s", path, dlerror()); 137 goto fail; 138 } 139 if ((ret->sk_api_version = dlsym(ret->dlhandle, 140 "sk_api_version")) == NULL) { 141 error("Provider \"%s\" dlsym(sk_api_version) failed: %s", 142 path, dlerror()); 143 goto fail; 144 } 145 version = ret->sk_api_version(); 146 debug_f("provider %s implements version 0x%08lx", ret->path, 147 (u_long)version); 148 if ((version & SSH_SK_VERSION_MAJOR_MASK) != SSH_SK_VERSION_MAJOR) { 149 error("Provider \"%s\" implements unsupported " 150 "version 0x%08lx (supported: 0x%08lx)", 151 path, (u_long)version, (u_long)SSH_SK_VERSION_MAJOR); 152 goto fail; 153 } 154 if ((ret->sk_enroll = dlsym(ret->dlhandle, "sk_enroll")) == NULL) { 155 error("Provider %s dlsym(sk_enroll) failed: %s", 156 path, dlerror()); 157 goto fail; 158 } 159 if ((ret->sk_sign = dlsym(ret->dlhandle, "sk_sign")) == NULL) { 160 error("Provider \"%s\" dlsym(sk_sign) failed: %s", 161 path, dlerror()); 162 goto fail; 163 } 164 if ((ret->sk_load_resident_keys = dlsym(ret->dlhandle, 165 "sk_load_resident_keys")) == NULL) { 166 error("Provider \"%s\" dlsym(sk_load_resident_keys) " 167 "failed: %s", path, dlerror()); 168 goto fail; 169 } 170 /* success */ 171 return ret; 172 fail: 173 sshsk_free(ret); 174 return NULL; 175 } 176 177 static void 178 sshsk_free_enroll_response(struct sk_enroll_response *r) 179 { 180 if (r == NULL) 181 return; 182 freezero(r->key_handle, r->key_handle_len); 183 freezero(r->public_key, r->public_key_len); 184 freezero(r->signature, r->signature_len); 185 freezero(r->attestation_cert, r->attestation_cert_len); 186 freezero(r->authdata, r->authdata_len); 187 freezero(r, sizeof(*r)); 188 } 189 190 static void 191 sshsk_free_sign_response(struct sk_sign_response *r) 192 { 193 if (r == NULL) 194 return; 195 freezero(r->sig_r, r->sig_r_len); 196 freezero(r->sig_s, r->sig_s_len); 197 freezero(r, sizeof(*r)); 198 } 199 200 #ifdef WITH_OPENSSL 201 /* Assemble key from response */ 202 static int 203 sshsk_ecdsa_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 204 { 205 struct sshkey *key = NULL; 206 struct sshbuf *b = NULL; 207 EC_POINT *q = NULL; 208 int r; 209 210 *keyp = NULL; 211 if ((key = sshkey_new(KEY_ECDSA_SK)) == NULL) { 212 error_f("sshkey_new failed"); 213 r = SSH_ERR_ALLOC_FAIL; 214 goto out; 215 } 216 key->ecdsa_nid = NID_X9_62_prime256v1; 217 if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL || 218 (q = EC_POINT_new(EC_KEY_get0_group(key->ecdsa))) == NULL || 219 (b = sshbuf_new()) == NULL) { 220 error_f("allocation failed"); 221 r = SSH_ERR_ALLOC_FAIL; 222 goto out; 223 } 224 if ((r = sshbuf_put_string(b, 225 resp->public_key, resp->public_key_len)) != 0) { 226 error_fr(r, "sshbuf_put_string"); 227 goto out; 228 } 229 if ((r = sshbuf_get_ec(b, q, EC_KEY_get0_group(key->ecdsa))) != 0) { 230 error_fr(r, "parse"); 231 r = SSH_ERR_INVALID_FORMAT; 232 goto out; 233 } 234 if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa), q) != 0) { 235 error("Authenticator returned invalid ECDSA key"); 236 r = SSH_ERR_KEY_INVALID_EC_VALUE; 237 goto out; 238 } 239 if (EC_KEY_set_public_key(key->ecdsa, q) != 1) { 240 /* XXX assume it is a allocation error */ 241 error_f("allocation failed"); 242 r = SSH_ERR_ALLOC_FAIL; 243 goto out; 244 } 245 /* success */ 246 *keyp = key; 247 key = NULL; /* transferred */ 248 r = 0; 249 out: 250 EC_POINT_free(q); 251 sshkey_free(key); 252 sshbuf_free(b); 253 return r; 254 } 255 #endif /* WITH_OPENSSL */ 256 257 static int 258 sshsk_ed25519_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 259 { 260 struct sshkey *key = NULL; 261 int r; 262 263 *keyp = NULL; 264 if (resp->public_key_len != ED25519_PK_SZ) { 265 error_f("invalid size: %zu", resp->public_key_len); 266 r = SSH_ERR_INVALID_FORMAT; 267 goto out; 268 } 269 if ((key = sshkey_new(KEY_ED25519_SK)) == NULL) { 270 error_f("sshkey_new failed"); 271 r = SSH_ERR_ALLOC_FAIL; 272 goto out; 273 } 274 if ((key->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) { 275 error_f("malloc failed"); 276 r = SSH_ERR_ALLOC_FAIL; 277 goto out; 278 } 279 memcpy(key->ed25519_pk, resp->public_key, ED25519_PK_SZ); 280 /* success */ 281 *keyp = key; 282 key = NULL; /* transferred */ 283 r = 0; 284 out: 285 sshkey_free(key); 286 return r; 287 } 288 289 static int 290 sshsk_key_from_response(int alg, const char *application, uint8_t flags, 291 struct sk_enroll_response *resp, struct sshkey **keyp) 292 { 293 struct sshkey *key = NULL; 294 int r = SSH_ERR_INTERNAL_ERROR; 295 296 *keyp = NULL; 297 298 /* Check response validity */ 299 if (resp->public_key == NULL || resp->key_handle == NULL) { 300 error_f("sk_enroll response invalid"); 301 r = SSH_ERR_INVALID_FORMAT; 302 goto out; 303 } 304 switch (alg) { 305 #ifdef WITH_OPENSSL 306 case SSH_SK_ECDSA: 307 if ((r = sshsk_ecdsa_assemble(resp, &key)) != 0) 308 goto out; 309 break; 310 #endif /* WITH_OPENSSL */ 311 case SSH_SK_ED25519: 312 if ((r = sshsk_ed25519_assemble(resp, &key)) != 0) 313 goto out; 314 break; 315 default: 316 error_f("unsupported algorithm %d", alg); 317 r = SSH_ERR_INVALID_ARGUMENT; 318 goto out; 319 } 320 key->sk_flags = flags; 321 if ((key->sk_key_handle = sshbuf_new()) == NULL || 322 (key->sk_reserved = sshbuf_new()) == NULL) { 323 error_f("allocation failed"); 324 r = SSH_ERR_ALLOC_FAIL; 325 goto out; 326 } 327 if ((key->sk_application = strdup(application)) == NULL) { 328 error_f("strdup application failed"); 329 r = SSH_ERR_ALLOC_FAIL; 330 goto out; 331 } 332 if ((r = sshbuf_put(key->sk_key_handle, resp->key_handle, 333 resp->key_handle_len)) != 0) { 334 error_fr(r, "put key handle"); 335 goto out; 336 } 337 /* success */ 338 r = 0; 339 *keyp = key; 340 key = NULL; 341 out: 342 sshkey_free(key); 343 return r; 344 } 345 346 static int 347 skerr_to_ssherr(int skerr) 348 { 349 switch (skerr) { 350 case SSH_SK_ERR_UNSUPPORTED: 351 return SSH_ERR_FEATURE_UNSUPPORTED; 352 case SSH_SK_ERR_PIN_REQUIRED: 353 return SSH_ERR_KEY_WRONG_PASSPHRASE; 354 case SSH_SK_ERR_DEVICE_NOT_FOUND: 355 return SSH_ERR_DEVICE_NOT_FOUND; 356 case SSH_SK_ERR_GENERAL: 357 default: 358 return SSH_ERR_INVALID_FORMAT; 359 } 360 } 361 362 static void 363 sshsk_free_options(struct sk_option **opts) 364 { 365 size_t i; 366 367 if (opts == NULL) 368 return; 369 for (i = 0; opts[i] != NULL; i++) { 370 free(opts[i]->name); 371 free(opts[i]->value); 372 free(opts[i]); 373 } 374 free(opts); 375 } 376 377 static int 378 sshsk_add_option(struct sk_option ***optsp, size_t *noptsp, 379 const char *name, const char *value, uint8_t required) 380 { 381 struct sk_option **opts = *optsp; 382 size_t nopts = *noptsp; 383 384 if ((opts = recallocarray(opts, nopts, nopts + 2, /* extra for NULL */ 385 sizeof(*opts))) == NULL) { 386 error_f("array alloc failed"); 387 return SSH_ERR_ALLOC_FAIL; 388 } 389 *optsp = opts; 390 *noptsp = nopts + 1; 391 if ((opts[nopts] = calloc(1, sizeof(**opts))) == NULL) { 392 error_f("alloc failed"); 393 return SSH_ERR_ALLOC_FAIL; 394 } 395 if ((opts[nopts]->name = strdup(name)) == NULL || 396 (opts[nopts]->value = strdup(value)) == NULL) { 397 error_f("alloc failed"); 398 return SSH_ERR_ALLOC_FAIL; 399 } 400 opts[nopts]->required = required; 401 return 0; 402 } 403 404 static int 405 make_options(const char *device, const char *user_id, 406 struct sk_option ***optsp) 407 { 408 struct sk_option **opts = NULL; 409 size_t nopts = 0; 410 int r, ret = SSH_ERR_INTERNAL_ERROR; 411 412 if (device != NULL && 413 (r = sshsk_add_option(&opts, &nopts, "device", device, 0)) != 0) { 414 ret = r; 415 goto out; 416 } 417 if (user_id != NULL && 418 (r = sshsk_add_option(&opts, &nopts, "user", user_id, 0)) != 0) { 419 ret = r; 420 goto out; 421 } 422 /* success */ 423 *optsp = opts; 424 opts = NULL; 425 nopts = 0; 426 ret = 0; 427 out: 428 sshsk_free_options(opts); 429 return ret; 430 } 431 432 433 static int 434 fill_attestation_blob(const struct sk_enroll_response *resp, 435 struct sshbuf *attest) 436 { 437 int r; 438 439 if (attest == NULL) 440 return 0; /* nothing to do */ 441 if ((r = sshbuf_put_cstring(attest, "ssh-sk-attest-v01")) != 0 || 442 (r = sshbuf_put_string(attest, 443 resp->attestation_cert, resp->attestation_cert_len)) != 0 || 444 (r = sshbuf_put_string(attest, 445 resp->signature, resp->signature_len)) != 0 || 446 (r = sshbuf_put_string(attest, 447 resp->authdata, resp->authdata_len)) != 0 || 448 (r = sshbuf_put_u32(attest, 0)) != 0 || /* resvd flags */ 449 (r = sshbuf_put_string(attest, NULL, 0)) != 0 /* resvd */) { 450 error_fr(r, "compose"); 451 return r; 452 } 453 /* success */ 454 return 0; 455 } 456 457 int 458 sshsk_enroll(int type, const char *provider_path, const char *device, 459 const char *application, const char *userid, uint8_t flags, 460 const char *pin, struct sshbuf *challenge_buf, 461 struct sshkey **keyp, struct sshbuf *attest) 462 { 463 struct sshsk_provider *skp = NULL; 464 struct sshkey *key = NULL; 465 u_char randchall[32]; 466 const u_char *challenge; 467 size_t challenge_len; 468 struct sk_enroll_response *resp = NULL; 469 struct sk_option **opts = NULL; 470 int r = SSH_ERR_INTERNAL_ERROR; 471 int alg; 472 473 debug_f("provider \"%s\", device \"%s\", application \"%s\", " 474 "userid \"%s\", flags 0x%02x, challenge len %zu%s", 475 provider_path, device, application, userid, flags, 476 challenge_buf == NULL ? 0 : sshbuf_len(challenge_buf), 477 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 478 479 *keyp = NULL; 480 if (attest) 481 sshbuf_reset(attest); 482 483 if ((r = make_options(device, userid, &opts)) != 0) 484 goto out; 485 486 switch (type) { 487 #ifdef WITH_OPENSSL 488 case KEY_ECDSA_SK: 489 alg = SSH_SK_ECDSA; 490 break; 491 #endif /* WITH_OPENSSL */ 492 case KEY_ED25519_SK: 493 alg = SSH_SK_ED25519; 494 break; 495 default: 496 error_f("unsupported key type"); 497 r = SSH_ERR_INVALID_ARGUMENT; 498 goto out; 499 } 500 if (provider_path == NULL) { 501 error_f("missing provider"); 502 r = SSH_ERR_INVALID_ARGUMENT; 503 goto out; 504 } 505 if (application == NULL || *application == '\0') { 506 error_f("missing application"); 507 r = SSH_ERR_INVALID_ARGUMENT; 508 goto out; 509 } 510 if (challenge_buf == NULL) { 511 debug_f("using random challenge"); 512 arc4random_buf(randchall, sizeof(randchall)); 513 challenge = randchall; 514 challenge_len = sizeof(randchall); 515 } else if (sshbuf_len(challenge_buf) == 0) { 516 error("Missing enrollment challenge"); 517 r = SSH_ERR_INVALID_ARGUMENT; 518 goto out; 519 } else { 520 challenge = sshbuf_ptr(challenge_buf); 521 challenge_len = sshbuf_len(challenge_buf); 522 debug3_f("using explicit challenge len=%zd", challenge_len); 523 } 524 if ((skp = sshsk_open(provider_path)) == NULL) { 525 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 526 goto out; 527 } 528 /* XXX validate flags? */ 529 /* enroll key */ 530 if ((r = skp->sk_enroll(alg, challenge, challenge_len, application, 531 flags, pin, opts, &resp)) != 0) { 532 debug_f("provider \"%s\" failure %d", provider_path, r); 533 r = skerr_to_ssherr(r); 534 goto out; 535 } 536 537 if ((r = sshsk_key_from_response(alg, application, resp->flags, 538 resp, &key)) != 0) 539 goto out; 540 541 /* Optionally fill in the attestation information */ 542 if ((r = fill_attestation_blob(resp, attest)) != 0) 543 goto out; 544 545 /* success */ 546 *keyp = key; 547 key = NULL; /* transferred */ 548 r = 0; 549 out: 550 sshsk_free_options(opts); 551 sshsk_free(skp); 552 sshkey_free(key); 553 sshsk_free_enroll_response(resp); 554 explicit_bzero(randchall, sizeof(randchall)); 555 return r; 556 } 557 558 #ifdef WITH_OPENSSL 559 static int 560 sshsk_ecdsa_sig(struct sk_sign_response *resp, struct sshbuf *sig) 561 { 562 struct sshbuf *inner_sig = NULL; 563 int r = SSH_ERR_INTERNAL_ERROR; 564 565 /* Check response validity */ 566 if (resp->sig_r == NULL || resp->sig_s == NULL) { 567 error_f("sk_sign response invalid"); 568 r = SSH_ERR_INVALID_FORMAT; 569 goto out; 570 } 571 if ((inner_sig = sshbuf_new()) == NULL) { 572 r = SSH_ERR_ALLOC_FAIL; 573 goto out; 574 } 575 /* Prepare and append inner signature object */ 576 if ((r = sshbuf_put_bignum2_bytes(inner_sig, 577 resp->sig_r, resp->sig_r_len)) != 0 || 578 (r = sshbuf_put_bignum2_bytes(inner_sig, 579 resp->sig_s, resp->sig_s_len)) != 0) { 580 error_fr(r, "compose inner"); 581 goto out; 582 } 583 if ((r = sshbuf_put_stringb(sig, inner_sig)) != 0 || 584 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 585 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 586 error_fr(r, "compose"); 587 goto out; 588 } 589 #ifdef DEBUG_SK 590 fprintf(stderr, "%s: sig_r:\n", __func__); 591 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 592 fprintf(stderr, "%s: sig_s:\n", __func__); 593 sshbuf_dump_data(resp->sig_s, resp->sig_s_len, stderr); 594 fprintf(stderr, "%s: inner:\n", __func__); 595 sshbuf_dump(inner_sig, stderr); 596 #endif 597 r = 0; 598 out: 599 sshbuf_free(inner_sig); 600 return r; 601 } 602 #endif /* WITH_OPENSSL */ 603 604 static int 605 sshsk_ed25519_sig(struct sk_sign_response *resp, struct sshbuf *sig) 606 { 607 int r = SSH_ERR_INTERNAL_ERROR; 608 609 /* Check response validity */ 610 if (resp->sig_r == NULL) { 611 error_f("sk_sign response invalid"); 612 r = SSH_ERR_INVALID_FORMAT; 613 goto out; 614 } 615 if ((r = sshbuf_put_string(sig, 616 resp->sig_r, resp->sig_r_len)) != 0 || 617 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 618 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 619 error_fr(r, "compose"); 620 goto out; 621 } 622 #ifdef DEBUG_SK 623 fprintf(stderr, "%s: sig_r:\n", __func__); 624 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 625 #endif 626 r = 0; 627 out: 628 return r; 629 } 630 631 int 632 sshsk_sign(const char *provider_path, struct sshkey *key, 633 u_char **sigp, size_t *lenp, const u_char *data, size_t datalen, 634 u_int compat, const char *pin) 635 { 636 struct sshsk_provider *skp = NULL; 637 int r = SSH_ERR_INTERNAL_ERROR; 638 int type, alg; 639 struct sk_sign_response *resp = NULL; 640 struct sshbuf *inner_sig = NULL, *sig = NULL; 641 struct sk_option **opts = NULL; 642 643 debug_f("provider \"%s\", key %s, flags 0x%02x%s", 644 provider_path, sshkey_type(key), key->sk_flags, 645 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 646 647 if (sigp != NULL) 648 *sigp = NULL; 649 if (lenp != NULL) 650 *lenp = 0; 651 type = sshkey_type_plain(key->type); 652 switch (type) { 653 #ifdef WITH_OPENSSL 654 case KEY_ECDSA_SK: 655 alg = SSH_SK_ECDSA; 656 break; 657 #endif /* WITH_OPENSSL */ 658 case KEY_ED25519_SK: 659 alg = SSH_SK_ED25519; 660 break; 661 default: 662 return SSH_ERR_INVALID_ARGUMENT; 663 } 664 if (provider_path == NULL || 665 key->sk_key_handle == NULL || 666 key->sk_application == NULL || *key->sk_application == '\0') { 667 r = SSH_ERR_INVALID_ARGUMENT; 668 goto out; 669 } 670 if ((skp = sshsk_open(provider_path)) == NULL) { 671 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 672 goto out; 673 } 674 #ifdef DEBUG_SK 675 fprintf(stderr, "%s: sk_flags = 0x%02x, sk_application = \"%s\"\n", 676 __func__, key->sk_flags, key->sk_application); 677 fprintf(stderr, "%s: sk_key_handle:\n", __func__); 678 sshbuf_dump(key->sk_key_handle, stderr); 679 #endif 680 if ((r = skp->sk_sign(alg, data, datalen, key->sk_application, 681 sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle), 682 key->sk_flags, pin, opts, &resp)) != 0) { 683 debug_f("sk_sign failed with code %d", r); 684 r = skerr_to_ssherr(r); 685 goto out; 686 } 687 /* Assemble signature */ 688 if ((sig = sshbuf_new()) == NULL) { 689 r = SSH_ERR_ALLOC_FAIL; 690 goto out; 691 } 692 if ((r = sshbuf_put_cstring(sig, sshkey_ssh_name_plain(key))) != 0) { 693 error_fr(r, "compose outer"); 694 goto out; 695 } 696 switch (type) { 697 #ifdef WITH_OPENSSL 698 case KEY_ECDSA_SK: 699 if ((r = sshsk_ecdsa_sig(resp, sig)) != 0) 700 goto out; 701 break; 702 #endif /* WITH_OPENSSL */ 703 case KEY_ED25519_SK: 704 if ((r = sshsk_ed25519_sig(resp, sig)) != 0) 705 goto out; 706 break; 707 } 708 #ifdef DEBUG_SK 709 fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n", 710 __func__, resp->flags, resp->counter); 711 fprintf(stderr, "%s: data to sign:\n", __func__); 712 sshbuf_dump_data(data, datalen, stderr); 713 fprintf(stderr, "%s: sigbuf:\n", __func__); 714 sshbuf_dump(sig, stderr); 715 #endif 716 if (sigp != NULL) { 717 if ((*sigp = malloc(sshbuf_len(sig))) == NULL) { 718 r = SSH_ERR_ALLOC_FAIL; 719 goto out; 720 } 721 memcpy(*sigp, sshbuf_ptr(sig), sshbuf_len(sig)); 722 } 723 if (lenp != NULL) 724 *lenp = sshbuf_len(sig); 725 /* success */ 726 r = 0; 727 out: 728 sshsk_free_options(opts); 729 sshsk_free(skp); 730 sshsk_free_sign_response(resp); 731 sshbuf_free(sig); 732 sshbuf_free(inner_sig); 733 return r; 734 } 735 736 static void 737 sshsk_free_sk_resident_keys(struct sk_resident_key **rks, size_t nrks) 738 { 739 size_t i; 740 741 if (nrks == 0 || rks == NULL) 742 return; 743 for (i = 0; i < nrks; i++) { 744 free(rks[i]->application); 745 freezero(rks[i]->user_id, rks[i]->user_id_len); 746 freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len); 747 freezero(rks[i]->key.public_key, rks[i]->key.public_key_len); 748 freezero(rks[i]->key.signature, rks[i]->key.signature_len); 749 freezero(rks[i]->key.attestation_cert, 750 rks[i]->key.attestation_cert_len); 751 freezero(rks[i], sizeof(**rks)); 752 } 753 free(rks); 754 } 755 756 static void 757 sshsk_free_resident_key(struct sshsk_resident_key *srk) 758 { 759 if (srk == NULL) 760 return; 761 sshkey_free(srk->key); 762 freezero(srk->user_id, srk->user_id_len); 763 free(srk); 764 } 765 766 767 void 768 sshsk_free_resident_keys(struct sshsk_resident_key **srks, size_t nsrks) 769 { 770 size_t i; 771 772 if (srks == NULL || nsrks == 0) 773 return; 774 775 for (i = 0; i < nsrks; i++) 776 sshsk_free_resident_key(srks[i]); 777 free(srks); 778 } 779 780 int 781 sshsk_load_resident(const char *provider_path, const char *device, 782 const char *pin, u_int flags, struct sshsk_resident_key ***srksp, 783 size_t *nsrksp) 784 { 785 struct sshsk_provider *skp = NULL; 786 int r = SSH_ERR_INTERNAL_ERROR; 787 struct sk_resident_key **rks = NULL; 788 size_t i, nrks = 0, nsrks = 0; 789 struct sshkey *key = NULL; 790 struct sshsk_resident_key *srk = NULL, **srks = NULL, **tmp; 791 uint8_t sk_flags; 792 struct sk_option **opts = NULL; 793 794 debug_f("provider \"%s\"%s", provider_path, 795 (pin != NULL && *pin != '\0') ? ", have-pin": ""); 796 797 if (srksp == NULL || nsrksp == NULL) 798 return SSH_ERR_INVALID_ARGUMENT; 799 *srksp = NULL; 800 *nsrksp = 0; 801 802 if ((r = make_options(device, NULL, &opts)) != 0) 803 goto out; 804 if ((skp = sshsk_open(provider_path)) == NULL) { 805 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 806 goto out; 807 } 808 if ((r = skp->sk_load_resident_keys(pin, opts, &rks, &nrks)) != 0) { 809 error("Provider \"%s\" returned failure %d", provider_path, r); 810 r = skerr_to_ssherr(r); 811 goto out; 812 } 813 for (i = 0; i < nrks; i++) { 814 debug3_f("rk %zu: slot %zu, alg %d, app \"%s\", uidlen %zu", 815 i, rks[i]->slot, rks[i]->alg, rks[i]->application, 816 rks[i]->user_id_len); 817 /* XXX need better filter here */ 818 if (strncmp(rks[i]->application, "ssh:", 4) != 0) 819 continue; 820 switch (rks[i]->alg) { 821 case SSH_SK_ECDSA: 822 case SSH_SK_ED25519: 823 break; 824 default: 825 continue; 826 } 827 sk_flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY; 828 if ((rks[i]->flags & SSH_SK_USER_VERIFICATION_REQD)) 829 sk_flags |= SSH_SK_USER_VERIFICATION_REQD; 830 if ((r = sshsk_key_from_response(rks[i]->alg, 831 rks[i]->application, sk_flags, &rks[i]->key, &key)) != 0) 832 goto out; 833 if ((srk = calloc(1, sizeof(*srk))) == NULL) { 834 error_f("calloc failed"); 835 r = SSH_ERR_ALLOC_FAIL; 836 goto out; 837 } 838 srk->key = key; 839 key = NULL; /* transferred */ 840 if ((srk->user_id = calloc(1, rks[i]->user_id_len)) == NULL) { 841 error_f("calloc failed"); 842 r = SSH_ERR_ALLOC_FAIL; 843 goto out; 844 } 845 memcpy(srk->user_id, rks[i]->user_id, rks[i]->user_id_len); 846 srk->user_id_len = rks[i]->user_id_len; 847 if ((tmp = recallocarray(srks, nsrks, nsrks + 1, 848 sizeof(*tmp))) == NULL) { 849 error_f("recallocarray failed"); 850 r = SSH_ERR_ALLOC_FAIL; 851 goto out; 852 } 853 srks = tmp; 854 srks[nsrks++] = srk; 855 srk = NULL; 856 /* XXX synthesise comment */ 857 } 858 /* success */ 859 *srksp = srks; 860 *nsrksp = nsrks; 861 srks = NULL; 862 nsrks = 0; 863 r = 0; 864 out: 865 sshsk_free_options(opts); 866 sshsk_free(skp); 867 sshsk_free_sk_resident_keys(rks, nrks); 868 sshkey_free(key); 869 sshsk_free_resident_key(srk); 870 sshsk_free_resident_keys(srks, nsrks); 871 return r; 872 } 873 874 #endif /* ENABLE_SK */ 875