ssh-sk.c revision 1.1.1.8
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 <dlfcn.h> 21 #include <stddef.h> 22 #include <stdint.h> 23 #include <string.h> 24 #include <stdio.h> 25 26 #ifdef WITH_OPENSSL 27 #include <openssl/objects.h> 28 #include <openssl/ec.h> 29 #include <openssl/evp.h> 30 #endif /* WITH_OPENSSL */ 31 32 #include "log.h" 33 #include "misc.h" 34 #include "sshbuf.h" 35 #include "sshkey.h" 36 #include "ssherr.h" 37 #include "digest.h" 38 39 #include "ssh-sk.h" 40 #include "sk-api.h" 41 #include "crypto_api.h" 42 43 struct sshsk_provider { 44 char *path; 45 void *dlhandle; 46 47 /* Return the version of the middleware API */ 48 uint32_t (*sk_api_version)(void); 49 50 /* Enroll a U2F key (private key generation) */ 51 int (*sk_enroll)(int alg, const uint8_t *challenge, 52 size_t challenge_len, const char *application, uint8_t flags, 53 const char *pin, struct sk_option **opts, 54 struct sk_enroll_response **enroll_response); 55 56 /* Sign a challenge */ 57 int (*sk_sign)(int alg, const uint8_t *message, size_t message_len, 58 const char *application, 59 const uint8_t *key_handle, size_t key_handle_len, 60 uint8_t flags, const char *pin, struct sk_option **opts, 61 struct sk_sign_response **sign_response); 62 63 /* Enumerate resident keys */ 64 int (*sk_load_resident_keys)(const char *pin, struct sk_option **opts, 65 struct sk_resident_key ***rks, size_t *nrks); 66 }; 67 68 /* Built-in version */ 69 int ssh_sk_enroll(int alg, const uint8_t *challenge, 70 size_t challenge_len, const char *application, uint8_t flags, 71 const char *pin, struct sk_option **opts, 72 struct sk_enroll_response **enroll_response); 73 int ssh_sk_sign(int alg, const uint8_t *message, size_t message_len, 74 const char *application, 75 const uint8_t *key_handle, size_t key_handle_len, 76 uint8_t flags, const char *pin, struct sk_option **opts, 77 struct sk_sign_response **sign_response); 78 int ssh_sk_load_resident_keys(const char *pin, struct sk_option **opts, 79 struct sk_resident_key ***rks, size_t *nrks); 80 81 static void 82 sshsk_free(struct sshsk_provider *p) 83 { 84 if (p == NULL) 85 return; 86 free(p->path); 87 if (p->dlhandle != NULL) 88 dlclose(p->dlhandle); 89 free(p); 90 } 91 92 static struct sshsk_provider * 93 sshsk_open(const char *path) 94 { 95 struct sshsk_provider *ret = NULL; 96 uint32_t version; 97 98 if (path == NULL || *path == '\0') { 99 error("No FIDO SecurityKeyProvider specified"); 100 return NULL; 101 } 102 if ((ret = calloc(1, sizeof(*ret))) == NULL) { 103 error_f("calloc failed"); 104 return NULL; 105 } 106 if ((ret->path = strdup(path)) == NULL) { 107 error_f("strdup failed"); 108 goto fail; 109 } 110 /* Skip the rest if we're using the linked in middleware */ 111 if (strcasecmp(ret->path, "internal") == 0) { 112 ret->sk_enroll = ssh_sk_enroll; 113 ret->sk_sign = ssh_sk_sign; 114 ret->sk_load_resident_keys = ssh_sk_load_resident_keys; 115 return ret; 116 } 117 if (lib_contains_symbol(path, "sk_api_version") != 0) { 118 error("provider %s is not an OpenSSH FIDO library", path); 119 goto fail; 120 } 121 if ((ret->dlhandle = dlopen(path, RTLD_NOW)) == NULL) { 122 error("Provider \"%s\" dlopen failed: %s", path, dlerror()); 123 goto fail; 124 } 125 if ((ret->sk_api_version = dlsym(ret->dlhandle, 126 "sk_api_version")) == NULL) { 127 fatal("Provider \"%s\" dlsym(sk_api_version) failed: %s", 128 path, dlerror()); 129 } 130 version = ret->sk_api_version(); 131 debug_f("provider %s implements version 0x%08lx", ret->path, 132 (u_long)version); 133 if ((version & SSH_SK_VERSION_MAJOR_MASK) != SSH_SK_VERSION_MAJOR) { 134 error("Provider \"%s\" implements unsupported " 135 "version 0x%08lx (supported: 0x%08lx)", 136 path, (u_long)version, (u_long)SSH_SK_VERSION_MAJOR); 137 goto fail; 138 } 139 if ((ret->sk_enroll = dlsym(ret->dlhandle, "sk_enroll")) == NULL) { 140 error("Provider %s dlsym(sk_enroll) failed: %s", 141 path, dlerror()); 142 goto fail; 143 } 144 if ((ret->sk_sign = dlsym(ret->dlhandle, "sk_sign")) == NULL) { 145 error("Provider \"%s\" dlsym(sk_sign) failed: %s", 146 path, dlerror()); 147 goto fail; 148 } 149 if ((ret->sk_load_resident_keys = dlsym(ret->dlhandle, 150 "sk_load_resident_keys")) == NULL) { 151 error("Provider \"%s\" dlsym(sk_load_resident_keys) " 152 "failed: %s", path, dlerror()); 153 goto fail; 154 } 155 /* success */ 156 return ret; 157 fail: 158 sshsk_free(ret); 159 return NULL; 160 } 161 162 static void 163 sshsk_free_enroll_response(struct sk_enroll_response *r) 164 { 165 if (r == NULL) 166 return; 167 freezero(r->key_handle, r->key_handle_len); 168 freezero(r->public_key, r->public_key_len); 169 freezero(r->signature, r->signature_len); 170 freezero(r->attestation_cert, r->attestation_cert_len); 171 freezero(r->authdata, r->authdata_len); 172 freezero(r, sizeof(*r)); 173 } 174 175 static void 176 sshsk_free_sign_response(struct sk_sign_response *r) 177 { 178 if (r == NULL) 179 return; 180 freezero(r->sig_r, r->sig_r_len); 181 freezero(r->sig_s, r->sig_s_len); 182 freezero(r, sizeof(*r)); 183 } 184 185 #ifdef WITH_OPENSSL 186 /* Assemble key from response */ 187 static int 188 sshsk_ecdsa_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 189 { 190 struct sshkey *key = NULL; 191 struct sshbuf *b = NULL; 192 EC_KEY *ecdsa = NULL; 193 EC_POINT *q = NULL; 194 const EC_GROUP *g = NULL; 195 int r; 196 197 *keyp = NULL; 198 if ((key = sshkey_new(KEY_ECDSA_SK)) == NULL) { 199 error_f("sshkey_new failed"); 200 r = SSH_ERR_ALLOC_FAIL; 201 goto out; 202 } 203 key->ecdsa_nid = NID_X9_62_prime256v1; 204 if ((ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL || 205 (g = EC_KEY_get0_group(ecdsa)) == NULL || 206 (q = EC_POINT_new(g)) == NULL || 207 (b = sshbuf_new()) == NULL) { 208 error_f("allocation failed"); 209 r = SSH_ERR_ALLOC_FAIL; 210 goto out; 211 } 212 if ((r = sshbuf_put_string(b, 213 resp->public_key, resp->public_key_len)) != 0) { 214 error_fr(r, "sshbuf_put_string"); 215 goto out; 216 } 217 if ((r = sshbuf_get_ec(b, q, g)) != 0) { 218 error_fr(r, "parse"); 219 r = SSH_ERR_INVALID_FORMAT; 220 goto out; 221 } 222 if (sshkey_ec_validate_public(g, q) != 0) { 223 error("Authenticator returned invalid ECDSA key"); 224 r = SSH_ERR_KEY_INVALID_EC_VALUE; 225 goto out; 226 } 227 if (EC_KEY_set_public_key(ecdsa, q) != 1) { 228 /* XXX assume it is a allocation error */ 229 error_f("allocation failed"); 230 r = SSH_ERR_ALLOC_FAIL; 231 goto out; 232 } 233 if ((key->pkey = EVP_PKEY_new()) == NULL) { 234 error_f("allocation failed"); 235 r = SSH_ERR_ALLOC_FAIL; 236 goto out; 237 } 238 if (EVP_PKEY_set1_EC_KEY(key->pkey, ecdsa) != 1) { 239 error_f("Assigning EC_KEY failed"); 240 r = SSH_ERR_LIBCRYPTO_ERROR; 241 goto out; 242 } 243 /* success */ 244 *keyp = key; 245 key = NULL; /* transferred */ 246 r = 0; 247 out: 248 sshkey_free(key); 249 sshbuf_free(b); 250 EC_KEY_free(ecdsa); 251 EC_POINT_free(q); 252 return r; 253 } 254 #endif /* WITH_OPENSSL */ 255 256 static int 257 sshsk_ed25519_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 258 { 259 struct sshkey *key = NULL; 260 int r; 261 262 *keyp = NULL; 263 if (resp->public_key_len != ED25519_PK_SZ) { 264 error_f("invalid size: %zu", resp->public_key_len); 265 r = SSH_ERR_INVALID_FORMAT; 266 goto out; 267 } 268 if ((key = sshkey_new(KEY_ED25519_SK)) == NULL) { 269 error_f("sshkey_new failed"); 270 r = SSH_ERR_ALLOC_FAIL; 271 goto out; 272 } 273 if ((key->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) { 274 error_f("malloc failed"); 275 r = SSH_ERR_ALLOC_FAIL; 276 goto out; 277 } 278 memcpy(key->ed25519_pk, resp->public_key, ED25519_PK_SZ); 279 /* success */ 280 *keyp = key; 281 key = NULL; /* transferred */ 282 r = 0; 283 out: 284 sshkey_free(key); 285 return r; 286 } 287 288 static int 289 sshsk_key_from_response(int alg, const char *application, uint8_t flags, 290 struct sk_enroll_response *resp, struct sshkey **keyp) 291 { 292 struct sshkey *key = NULL; 293 int r = SSH_ERR_INTERNAL_ERROR; 294 295 *keyp = NULL; 296 297 /* Check response validity */ 298 if (resp->public_key == NULL || resp->key_handle == NULL) { 299 error_f("sk_enroll response invalid"); 300 r = SSH_ERR_INVALID_FORMAT; 301 goto out; 302 } 303 switch (alg) { 304 #ifdef WITH_OPENSSL 305 case SSH_SK_ECDSA: 306 if ((r = sshsk_ecdsa_assemble(resp, &key)) != 0) 307 goto out; 308 break; 309 #endif /* WITH_OPENSSL */ 310 case SSH_SK_ED25519: 311 if ((r = sshsk_ed25519_assemble(resp, &key)) != 0) 312 goto out; 313 break; 314 default: 315 error_f("unsupported algorithm %d", alg); 316 r = SSH_ERR_INVALID_ARGUMENT; 317 goto out; 318 } 319 key->sk_flags = flags; 320 if ((key->sk_key_handle = sshbuf_new()) == NULL || 321 (key->sk_reserved = sshbuf_new()) == NULL) { 322 error_f("allocation failed"); 323 r = SSH_ERR_ALLOC_FAIL; 324 goto out; 325 } 326 if ((key->sk_application = strdup(application)) == NULL) { 327 error_f("strdup application failed"); 328 r = SSH_ERR_ALLOC_FAIL; 329 goto out; 330 } 331 if ((r = sshbuf_put(key->sk_key_handle, resp->key_handle, 332 resp->key_handle_len)) != 0) { 333 error_fr(r, "put key handle"); 334 goto out; 335 } 336 /* success */ 337 r = 0; 338 *keyp = key; 339 key = NULL; 340 out: 341 sshkey_free(key); 342 return r; 343 } 344 345 static int 346 skerr_to_ssherr(int skerr) 347 { 348 switch (skerr) { 349 case SSH_SK_ERR_UNSUPPORTED: 350 return SSH_ERR_FEATURE_UNSUPPORTED; 351 case SSH_SK_ERR_PIN_REQUIRED: 352 return SSH_ERR_KEY_WRONG_PASSPHRASE; 353 case SSH_SK_ERR_DEVICE_NOT_FOUND: 354 return SSH_ERR_DEVICE_NOT_FOUND; 355 case SSH_SK_ERR_CREDENTIAL_EXISTS: 356 return SSH_ERR_KEY_BAD_PERMISSIONS; 357 case SSH_SK_ERR_GENERAL: 358 default: 359 return SSH_ERR_INVALID_FORMAT; 360 } 361 } 362 363 static void 364 sshsk_free_options(struct sk_option **opts) 365 { 366 size_t i; 367 368 if (opts == NULL) 369 return; 370 for (i = 0; opts[i] != NULL; i++) { 371 free(opts[i]->name); 372 free(opts[i]->value); 373 free(opts[i]); 374 } 375 free(opts); 376 } 377 378 static int 379 sshsk_add_option(struct sk_option ***optsp, size_t *noptsp, 380 const char *name, const char *value, uint8_t required) 381 { 382 struct sk_option **opts = *optsp; 383 size_t nopts = *noptsp; 384 385 if ((opts = recallocarray(opts, nopts, nopts + 2, /* extra for NULL */ 386 sizeof(*opts))) == NULL) { 387 error_f("array alloc failed"); 388 return SSH_ERR_ALLOC_FAIL; 389 } 390 *optsp = opts; 391 *noptsp = nopts + 1; 392 if ((opts[nopts] = calloc(1, sizeof(**opts))) == NULL) { 393 error_f("alloc failed"); 394 return SSH_ERR_ALLOC_FAIL; 395 } 396 if ((opts[nopts]->name = strdup(name)) == NULL || 397 (opts[nopts]->value = strdup(value)) == NULL) { 398 error_f("alloc failed"); 399 return SSH_ERR_ALLOC_FAIL; 400 } 401 opts[nopts]->required = required; 402 return 0; 403 } 404 405 static int 406 make_options(const char *device, const char *user_id, 407 struct sk_option ***optsp) 408 { 409 struct sk_option **opts = NULL; 410 size_t nopts = 0; 411 int r, ret = SSH_ERR_INTERNAL_ERROR; 412 413 if (device != NULL && 414 (r = sshsk_add_option(&opts, &nopts, "device", device, 0)) != 0) { 415 ret = r; 416 goto out; 417 } 418 if (user_id != NULL && 419 (r = sshsk_add_option(&opts, &nopts, "user", user_id, 0)) != 0) { 420 ret = r; 421 goto out; 422 } 423 /* success */ 424 *optsp = opts; 425 opts = NULL; 426 nopts = 0; 427 ret = 0; 428 out: 429 sshsk_free_options(opts); 430 return ret; 431 } 432 433 434 static int 435 fill_attestation_blob(const struct sk_enroll_response *resp, 436 struct sshbuf *attest) 437 { 438 int r; 439 440 if (attest == NULL) 441 return 0; /* nothing to do */ 442 if ((r = sshbuf_put_cstring(attest, "ssh-sk-attest-v01")) != 0 || 443 (r = sshbuf_put_string(attest, 444 resp->attestation_cert, resp->attestation_cert_len)) != 0 || 445 (r = sshbuf_put_string(attest, 446 resp->signature, resp->signature_len)) != 0 || 447 (r = sshbuf_put_string(attest, 448 resp->authdata, resp->authdata_len)) != 0 || 449 (r = sshbuf_put_u32(attest, 0)) != 0 || /* resvd flags */ 450 (r = sshbuf_put_string(attest, NULL, 0)) != 0 /* resvd */) { 451 error_fr(r, "compose"); 452 return r; 453 } 454 /* success */ 455 return 0; 456 } 457 458 int 459 sshsk_enroll(int type, const char *provider_path, const char *device, 460 const char *application, const char *userid, uint8_t flags, 461 const char *pin, struct sshbuf *challenge_buf, 462 struct sshkey **keyp, struct sshbuf *attest) 463 { 464 struct sshsk_provider *skp = NULL; 465 struct sshkey *key = NULL; 466 u_char randchall[32]; 467 const u_char *challenge; 468 size_t challenge_len; 469 struct sk_enroll_response *resp = NULL; 470 struct sk_option **opts = NULL; 471 int r = SSH_ERR_INTERNAL_ERROR; 472 int alg; 473 474 debug_f("provider \"%s\", device \"%s\", application \"%s\", " 475 "userid \"%s\", flags 0x%02x, challenge len %zu%s", 476 provider_path, device, application, userid, flags, 477 challenge_buf == NULL ? 0 : sshbuf_len(challenge_buf), 478 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 479 480 *keyp = NULL; 481 if (attest) 482 sshbuf_reset(attest); 483 484 if ((r = make_options(device, userid, &opts)) != 0) 485 goto out; 486 487 switch (type) { 488 #ifdef WITH_OPENSSL 489 case KEY_ECDSA_SK: 490 alg = SSH_SK_ECDSA; 491 break; 492 #endif /* WITH_OPENSSL */ 493 case KEY_ED25519_SK: 494 alg = SSH_SK_ED25519; 495 break; 496 default: 497 error_f("unsupported key type"); 498 r = SSH_ERR_INVALID_ARGUMENT; 499 goto out; 500 } 501 if (provider_path == NULL) { 502 error_f("missing provider"); 503 r = SSH_ERR_INVALID_ARGUMENT; 504 goto out; 505 } 506 if (application == NULL || *application == '\0') { 507 error_f("missing application"); 508 r = SSH_ERR_INVALID_ARGUMENT; 509 goto out; 510 } 511 if (challenge_buf == NULL) { 512 debug_f("using random challenge"); 513 arc4random_buf(randchall, sizeof(randchall)); 514 challenge = randchall; 515 challenge_len = sizeof(randchall); 516 } else if (sshbuf_len(challenge_buf) == 0) { 517 error("Missing enrollment challenge"); 518 r = SSH_ERR_INVALID_ARGUMENT; 519 goto out; 520 } else { 521 challenge = sshbuf_ptr(challenge_buf); 522 challenge_len = sshbuf_len(challenge_buf); 523 debug3_f("using explicit challenge len=%zd", challenge_len); 524 } 525 if ((skp = sshsk_open(provider_path)) == NULL) { 526 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 527 goto out; 528 } 529 /* XXX validate flags? */ 530 /* enroll key */ 531 if ((r = skp->sk_enroll(alg, challenge, challenge_len, application, 532 flags, pin, opts, &resp)) != 0) { 533 debug_f("provider \"%s\" failure %d", provider_path, r); 534 r = skerr_to_ssherr(r); 535 goto out; 536 } 537 538 if ((r = sshsk_key_from_response(alg, application, resp->flags, 539 resp, &key)) != 0) 540 goto out; 541 542 /* Optionally fill in the attestation information */ 543 if ((r = fill_attestation_blob(resp, attest)) != 0) 544 goto out; 545 546 /* success */ 547 *keyp = key; 548 key = NULL; /* transferred */ 549 r = 0; 550 out: 551 sshsk_free_options(opts); 552 sshsk_free(skp); 553 sshkey_free(key); 554 sshsk_free_enroll_response(resp); 555 explicit_bzero(randchall, sizeof(randchall)); 556 return r; 557 } 558 559 #ifdef WITH_OPENSSL 560 static int 561 sshsk_ecdsa_sig(struct sk_sign_response *resp, struct sshbuf *sig) 562 { 563 struct sshbuf *inner_sig = NULL; 564 int r = SSH_ERR_INTERNAL_ERROR; 565 566 /* Check response validity */ 567 if (resp->sig_r == NULL || resp->sig_s == NULL) { 568 error_f("sk_sign response invalid"); 569 r = SSH_ERR_INVALID_FORMAT; 570 goto out; 571 } 572 if ((inner_sig = sshbuf_new()) == NULL) { 573 r = SSH_ERR_ALLOC_FAIL; 574 goto out; 575 } 576 /* Prepare and append inner signature object */ 577 if ((r = sshbuf_put_bignum2_bytes(inner_sig, 578 resp->sig_r, resp->sig_r_len)) != 0 || 579 (r = sshbuf_put_bignum2_bytes(inner_sig, 580 resp->sig_s, resp->sig_s_len)) != 0) { 581 error_fr(r, "compose inner"); 582 goto out; 583 } 584 if ((r = sshbuf_put_stringb(sig, inner_sig)) != 0 || 585 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 586 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 587 error_fr(r, "compose"); 588 goto out; 589 } 590 #ifdef DEBUG_SK 591 fprintf(stderr, "%s: sig_r:\n", __func__); 592 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 593 fprintf(stderr, "%s: sig_s:\n", __func__); 594 sshbuf_dump_data(resp->sig_s, resp->sig_s_len, stderr); 595 fprintf(stderr, "%s: inner:\n", __func__); 596 sshbuf_dump(inner_sig, stderr); 597 #endif 598 r = 0; 599 out: 600 sshbuf_free(inner_sig); 601 return r; 602 } 603 #endif /* WITH_OPENSSL */ 604 605 static int 606 sshsk_ed25519_sig(struct sk_sign_response *resp, struct sshbuf *sig) 607 { 608 int r = SSH_ERR_INTERNAL_ERROR; 609 610 /* Check response validity */ 611 if (resp->sig_r == NULL) { 612 error_f("sk_sign response invalid"); 613 r = SSH_ERR_INVALID_FORMAT; 614 goto out; 615 } 616 if ((r = sshbuf_put_string(sig, 617 resp->sig_r, resp->sig_r_len)) != 0 || 618 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 619 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 620 error_fr(r, "compose"); 621 goto out; 622 } 623 #ifdef DEBUG_SK 624 fprintf(stderr, "%s: sig_r:\n", __func__); 625 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 626 #endif 627 r = 0; 628 out: 629 return r; 630 } 631 632 int 633 sshsk_sign(const char *provider_path, struct sshkey *key, 634 u_char **sigp, size_t *lenp, const u_char *data, size_t datalen, 635 u_int compat, const char *pin) 636 { 637 struct sshsk_provider *skp = NULL; 638 int r = SSH_ERR_INTERNAL_ERROR; 639 int type, alg; 640 struct sk_sign_response *resp = NULL; 641 struct sshbuf *inner_sig = NULL, *sig = NULL; 642 struct sk_option **opts = NULL; 643 644 debug_f("provider \"%s\", key %s, flags 0x%02x%s", 645 provider_path, sshkey_type(key), key->sk_flags, 646 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 647 648 if (sigp != NULL) 649 *sigp = NULL; 650 if (lenp != NULL) 651 *lenp = 0; 652 type = sshkey_type_plain(key->type); 653 switch (type) { 654 #ifdef WITH_OPENSSL 655 case KEY_ECDSA_SK: 656 alg = SSH_SK_ECDSA; 657 break; 658 #endif /* WITH_OPENSSL */ 659 case KEY_ED25519_SK: 660 alg = SSH_SK_ED25519; 661 break; 662 default: 663 return SSH_ERR_INVALID_ARGUMENT; 664 } 665 if (provider_path == NULL || 666 key->sk_key_handle == NULL || 667 key->sk_application == NULL || *key->sk_application == '\0') { 668 r = SSH_ERR_INVALID_ARGUMENT; 669 goto out; 670 } 671 if ((skp = sshsk_open(provider_path)) == NULL) { 672 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 673 goto out; 674 } 675 #ifdef DEBUG_SK 676 fprintf(stderr, "%s: sk_flags = 0x%02x, sk_application = \"%s\"\n", 677 __func__, key->sk_flags, key->sk_application); 678 fprintf(stderr, "%s: sk_key_handle:\n", __func__); 679 sshbuf_dump(key->sk_key_handle, stderr); 680 #endif 681 if ((r = skp->sk_sign(alg, data, datalen, key->sk_application, 682 sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle), 683 key->sk_flags, pin, opts, &resp)) != 0) { 684 debug_f("sk_sign failed with code %d", r); 685 r = skerr_to_ssherr(r); 686 goto out; 687 } 688 /* Assemble signature */ 689 if ((sig = sshbuf_new()) == NULL) { 690 r = SSH_ERR_ALLOC_FAIL; 691 goto out; 692 } 693 if ((r = sshbuf_put_cstring(sig, sshkey_ssh_name_plain(key))) != 0) { 694 error_fr(r, "compose outer"); 695 goto out; 696 } 697 switch (type) { 698 #ifdef WITH_OPENSSL 699 case KEY_ECDSA_SK: 700 if ((r = sshsk_ecdsa_sig(resp, sig)) != 0) 701 goto out; 702 break; 703 #endif /* WITH_OPENSSL */ 704 case KEY_ED25519_SK: 705 if ((r = sshsk_ed25519_sig(resp, sig)) != 0) 706 goto out; 707 break; 708 } 709 #ifdef DEBUG_SK 710 fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n", 711 __func__, resp->flags, resp->counter); 712 fprintf(stderr, "%s: data to sign:\n", __func__); 713 sshbuf_dump_data(data, datalen, stderr); 714 fprintf(stderr, "%s: sigbuf:\n", __func__); 715 sshbuf_dump(sig, stderr); 716 #endif 717 if (sigp != NULL) { 718 if ((*sigp = malloc(sshbuf_len(sig))) == NULL) { 719 r = SSH_ERR_ALLOC_FAIL; 720 goto out; 721 } 722 memcpy(*sigp, sshbuf_ptr(sig), sshbuf_len(sig)); 723 } 724 if (lenp != NULL) 725 *lenp = sshbuf_len(sig); 726 /* success */ 727 r = 0; 728 out: 729 sshsk_free_options(opts); 730 sshsk_free(skp); 731 sshsk_free_sign_response(resp); 732 sshbuf_free(sig); 733 sshbuf_free(inner_sig); 734 return r; 735 } 736 737 static void 738 sshsk_free_sk_resident_keys(struct sk_resident_key **rks, size_t nrks) 739 { 740 size_t i; 741 742 if (nrks == 0 || rks == NULL) 743 return; 744 for (i = 0; i < nrks; i++) { 745 free(rks[i]->application); 746 freezero(rks[i]->user_id, rks[i]->user_id_len); 747 freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len); 748 freezero(rks[i]->key.public_key, rks[i]->key.public_key_len); 749 freezero(rks[i]->key.signature, rks[i]->key.signature_len); 750 freezero(rks[i]->key.attestation_cert, 751 rks[i]->key.attestation_cert_len); 752 freezero(rks[i], sizeof(**rks)); 753 } 754 free(rks); 755 } 756 757 static void 758 sshsk_free_resident_key(struct sshsk_resident_key *srk) 759 { 760 if (srk == NULL) 761 return; 762 sshkey_free(srk->key); 763 freezero(srk->user_id, srk->user_id_len); 764 free(srk); 765 } 766 767 768 void 769 sshsk_free_resident_keys(struct sshsk_resident_key **srks, size_t nsrks) 770 { 771 size_t i; 772 773 if (srks == NULL || nsrks == 0) 774 return; 775 776 for (i = 0; i < nsrks; i++) 777 sshsk_free_resident_key(srks[i]); 778 free(srks); 779 } 780 781 int 782 sshsk_load_resident(const char *provider_path, const char *device, 783 const char *pin, u_int flags, struct sshsk_resident_key ***srksp, 784 size_t *nsrksp) 785 { 786 struct sshsk_provider *skp = NULL; 787 int r = SSH_ERR_INTERNAL_ERROR; 788 struct sk_resident_key **rks = NULL; 789 size_t i, nrks = 0, nsrks = 0; 790 struct sshkey *key = NULL; 791 struct sshsk_resident_key *srk = NULL, **srks = NULL, **tmp; 792 uint8_t sk_flags; 793 struct sk_option **opts = NULL; 794 795 debug_f("provider \"%s\"%s", provider_path, 796 (pin != NULL && *pin != '\0') ? ", have-pin": ""); 797 798 if (srksp == NULL || nsrksp == NULL) 799 return SSH_ERR_INVALID_ARGUMENT; 800 *srksp = NULL; 801 *nsrksp = 0; 802 803 if ((r = make_options(device, NULL, &opts)) != 0) 804 goto out; 805 if ((skp = sshsk_open(provider_path)) == NULL) { 806 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 807 goto out; 808 } 809 if ((r = skp->sk_load_resident_keys(pin, opts, &rks, &nrks)) != 0) { 810 error("Provider \"%s\" returned failure %d", provider_path, r); 811 r = skerr_to_ssherr(r); 812 goto out; 813 } 814 for (i = 0; i < nrks; i++) { 815 debug3_f("rk %zu: slot %zu, alg %d, app \"%s\", uidlen %zu", 816 i, rks[i]->slot, rks[i]->alg, rks[i]->application, 817 rks[i]->user_id_len); 818 /* XXX need better filter here */ 819 if (strncmp(rks[i]->application, "ssh:", 4) != 0) 820 continue; 821 switch (rks[i]->alg) { 822 case SSH_SK_ECDSA: 823 case SSH_SK_ED25519: 824 break; 825 default: 826 continue; 827 } 828 sk_flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY; 829 if ((rks[i]->flags & SSH_SK_USER_VERIFICATION_REQD)) 830 sk_flags |= SSH_SK_USER_VERIFICATION_REQD; 831 if ((r = sshsk_key_from_response(rks[i]->alg, 832 rks[i]->application, sk_flags, &rks[i]->key, &key)) != 0) 833 goto out; 834 if ((srk = calloc(1, sizeof(*srk))) == NULL) { 835 error_f("calloc failed"); 836 r = SSH_ERR_ALLOC_FAIL; 837 goto out; 838 } 839 srk->key = key; 840 key = NULL; /* transferred */ 841 if ((srk->user_id = calloc(1, rks[i]->user_id_len)) == NULL) { 842 error_f("calloc failed"); 843 r = SSH_ERR_ALLOC_FAIL; 844 goto out; 845 } 846 memcpy(srk->user_id, rks[i]->user_id, rks[i]->user_id_len); 847 srk->user_id_len = rks[i]->user_id_len; 848 if ((tmp = recallocarray(srks, nsrks, nsrks + 1, 849 sizeof(*tmp))) == NULL) { 850 error_f("recallocarray failed"); 851 r = SSH_ERR_ALLOC_FAIL; 852 goto out; 853 } 854 srks = tmp; 855 srks[nsrks++] = srk; 856 srk = NULL; 857 /* XXX synthesise comment */ 858 } 859 /* success */ 860 *srksp = srks; 861 *nsrksp = nsrks; 862 srks = NULL; 863 nsrks = 0; 864 r = 0; 865 out: 866 sshsk_free_options(opts); 867 sshsk_free(skp); 868 sshsk_free_sk_resident_keys(rks, nrks); 869 sshkey_free(key); 870 sshsk_free_resident_key(srk); 871 sshsk_free_resident_keys(srks, nsrks); 872 return r; 873 } 874 875
Indexes created Tue Mar 17 00:23:13 UTC 2026