ssh-sk.c revision 1.1.1.7
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 <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 #endif /* WITH_OPENSSL */ 30 31 #include "log.h" 32 #include "misc.h" 33 #include "sshbuf.h" 34 #include "sshkey.h" 35 #include "ssherr.h" 36 #include "digest.h" 37 38 #include "ssh-sk.h" 39 #include "sk-api.h" 40 #include "crypto_api.h" 41 42 struct sshsk_provider { 43 char *path; 44 void *dlhandle; 45 46 /* Return the version of the middleware API */ 47 uint32_t (*sk_api_version)(void); 48 49 /* Enroll a U2F key (private key generation) */ 50 int (*sk_enroll)(int alg, const uint8_t *challenge, 51 size_t challenge_len, const char *application, uint8_t flags, 52 const char *pin, struct sk_option **opts, 53 struct sk_enroll_response **enroll_response); 54 55 /* Sign a challenge */ 56 int (*sk_sign)(int alg, const uint8_t *message, size_t message_len, 57 const char *application, 58 const uint8_t *key_handle, size_t key_handle_len, 59 uint8_t flags, const char *pin, struct sk_option **opts, 60 struct sk_sign_response **sign_response); 61 62 /* Enumerate resident keys */ 63 int (*sk_load_resident_keys)(const char *pin, struct sk_option **opts, 64 struct sk_resident_key ***rks, size_t *nrks); 65 }; 66 67 /* Built-in version */ 68 int ssh_sk_enroll(int alg, const uint8_t *challenge, 69 size_t challenge_len, const char *application, uint8_t flags, 70 const char *pin, struct sk_option **opts, 71 struct sk_enroll_response **enroll_response); 72 int ssh_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 int ssh_sk_load_resident_keys(const char *pin, struct sk_option **opts, 78 struct sk_resident_key ***rks, size_t *nrks); 79 80 static void 81 sshsk_free(struct sshsk_provider *p) 82 { 83 if (p == NULL) 84 return; 85 free(p->path); 86 if (p->dlhandle != NULL) 87 dlclose(p->dlhandle); 88 free(p); 89 } 90 91 static struct sshsk_provider * 92 sshsk_open(const char *path) 93 { 94 struct sshsk_provider *ret = NULL; 95 uint32_t version; 96 97 if (path == NULL || *path == '\0') { 98 error("No FIDO SecurityKeyProvider specified"); 99 return NULL; 100 } 101 if ((ret = calloc(1, sizeof(*ret))) == NULL) { 102 error_f("calloc failed"); 103 return NULL; 104 } 105 if ((ret->path = strdup(path)) == NULL) { 106 error_f("strdup failed"); 107 goto fail; 108 } 109 /* Skip the rest if we're using the linked in middleware */ 110 if (strcasecmp(ret->path, "internal") == 0) { 111 ret->sk_enroll = ssh_sk_enroll; 112 ret->sk_sign = ssh_sk_sign; 113 ret->sk_load_resident_keys = ssh_sk_load_resident_keys; 114 return ret; 115 } 116 if (lib_contains_symbol(path, "sk_api_version") != 0) { 117 error("provider %s is not an OpenSSH FIDO library", path); 118 goto fail; 119 } 120 if ((ret->dlhandle = dlopen(path, RTLD_NOW)) == NULL) { 121 error("Provider \"%s\" dlopen failed: %s", path, dlerror()); 122 goto fail; 123 } 124 if ((ret->sk_api_version = dlsym(ret->dlhandle, 125 "sk_api_version")) == NULL) { 126 fatal("Provider \"%s\" dlsym(sk_api_version) failed: %s", 127 path, dlerror()); 128 } 129 version = ret->sk_api_version(); 130 debug_f("provider %s implements version 0x%08lx", ret->path, 131 (u_long)version); 132 if ((version & SSH_SK_VERSION_MAJOR_MASK) != SSH_SK_VERSION_MAJOR) { 133 error("Provider \"%s\" implements unsupported " 134 "version 0x%08lx (supported: 0x%08lx)", 135 path, (u_long)version, (u_long)SSH_SK_VERSION_MAJOR); 136 goto fail; 137 } 138 if ((ret->sk_enroll = dlsym(ret->dlhandle, "sk_enroll")) == NULL) { 139 error("Provider %s dlsym(sk_enroll) failed: %s", 140 path, dlerror()); 141 goto fail; 142 } 143 if ((ret->sk_sign = dlsym(ret->dlhandle, "sk_sign")) == NULL) { 144 error("Provider \"%s\" dlsym(sk_sign) failed: %s", 145 path, dlerror()); 146 goto fail; 147 } 148 if ((ret->sk_load_resident_keys = dlsym(ret->dlhandle, 149 "sk_load_resident_keys")) == NULL) { 150 error("Provider \"%s\" dlsym(sk_load_resident_keys) " 151 "failed: %s", path, dlerror()); 152 goto fail; 153 } 154 /* success */ 155 return ret; 156 fail: 157 sshsk_free(ret); 158 return NULL; 159 } 160 161 static void 162 sshsk_free_enroll_response(struct sk_enroll_response *r) 163 { 164 if (r == NULL) 165 return; 166 freezero(r->key_handle, r->key_handle_len); 167 freezero(r->public_key, r->public_key_len); 168 freezero(r->signature, r->signature_len); 169 freezero(r->attestation_cert, r->attestation_cert_len); 170 freezero(r->authdata, r->authdata_len); 171 freezero(r, sizeof(*r)); 172 } 173 174 static void 175 sshsk_free_sign_response(struct sk_sign_response *r) 176 { 177 if (r == NULL) 178 return; 179 freezero(r->sig_r, r->sig_r_len); 180 freezero(r->sig_s, r->sig_s_len); 181 freezero(r, sizeof(*r)); 182 } 183 184 #ifdef WITH_OPENSSL 185 /* Assemble key from response */ 186 static int 187 sshsk_ecdsa_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 188 { 189 struct sshkey *key = NULL; 190 struct sshbuf *b = NULL; 191 EC_POINT *q = NULL; 192 int r; 193 194 *keyp = NULL; 195 if ((key = sshkey_new(KEY_ECDSA_SK)) == NULL) { 196 error_f("sshkey_new failed"); 197 r = SSH_ERR_ALLOC_FAIL; 198 goto out; 199 } 200 key->ecdsa_nid = NID_X9_62_prime256v1; 201 if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL || 202 (q = EC_POINT_new(EC_KEY_get0_group(key->ecdsa))) == NULL || 203 (b = sshbuf_new()) == NULL) { 204 error_f("allocation failed"); 205 r = SSH_ERR_ALLOC_FAIL; 206 goto out; 207 } 208 if ((r = sshbuf_put_string(b, 209 resp->public_key, resp->public_key_len)) != 0) { 210 error_fr(r, "sshbuf_put_string"); 211 goto out; 212 } 213 if ((r = sshbuf_get_ec(b, q, EC_KEY_get0_group(key->ecdsa))) != 0) { 214 error_fr(r, "parse"); 215 r = SSH_ERR_INVALID_FORMAT; 216 goto out; 217 } 218 if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa), q) != 0) { 219 error("Authenticator returned invalid ECDSA key"); 220 r = SSH_ERR_KEY_INVALID_EC_VALUE; 221 goto out; 222 } 223 if (EC_KEY_set_public_key(key->ecdsa, q) != 1) { 224 /* XXX assume it is a allocation error */ 225 error_f("allocation failed"); 226 r = SSH_ERR_ALLOC_FAIL; 227 goto out; 228 } 229 /* success */ 230 *keyp = key; 231 key = NULL; /* transferred */ 232 r = 0; 233 out: 234 EC_POINT_free(q); 235 sshkey_free(key); 236 sshbuf_free(b); 237 return r; 238 } 239 #endif /* WITH_OPENSSL */ 240 241 static int 242 sshsk_ed25519_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 243 { 244 struct sshkey *key = NULL; 245 int r; 246 247 *keyp = NULL; 248 if (resp->public_key_len != ED25519_PK_SZ) { 249 error_f("invalid size: %zu", resp->public_key_len); 250 r = SSH_ERR_INVALID_FORMAT; 251 goto out; 252 } 253 if ((key = sshkey_new(KEY_ED25519_SK)) == NULL) { 254 error_f("sshkey_new failed"); 255 r = SSH_ERR_ALLOC_FAIL; 256 goto out; 257 } 258 if ((key->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) { 259 error_f("malloc failed"); 260 r = SSH_ERR_ALLOC_FAIL; 261 goto out; 262 } 263 memcpy(key->ed25519_pk, resp->public_key, ED25519_PK_SZ); 264 /* success */ 265 *keyp = key; 266 key = NULL; /* transferred */ 267 r = 0; 268 out: 269 sshkey_free(key); 270 return r; 271 } 272 273 static int 274 sshsk_key_from_response(int alg, const char *application, uint8_t flags, 275 struct sk_enroll_response *resp, struct sshkey **keyp) 276 { 277 struct sshkey *key = NULL; 278 int r = SSH_ERR_INTERNAL_ERROR; 279 280 *keyp = NULL; 281 282 /* Check response validity */ 283 if (resp->public_key == NULL || resp->key_handle == NULL) { 284 error_f("sk_enroll response invalid"); 285 r = SSH_ERR_INVALID_FORMAT; 286 goto out; 287 } 288 switch (alg) { 289 #ifdef WITH_OPENSSL 290 case SSH_SK_ECDSA: 291 if ((r = sshsk_ecdsa_assemble(resp, &key)) != 0) 292 goto out; 293 break; 294 #endif /* WITH_OPENSSL */ 295 case SSH_SK_ED25519: 296 if ((r = sshsk_ed25519_assemble(resp, &key)) != 0) 297 goto out; 298 break; 299 default: 300 error_f("unsupported algorithm %d", alg); 301 r = SSH_ERR_INVALID_ARGUMENT; 302 goto out; 303 } 304 key->sk_flags = flags; 305 if ((key->sk_key_handle = sshbuf_new()) == NULL || 306 (key->sk_reserved = sshbuf_new()) == NULL) { 307 error_f("allocation failed"); 308 r = SSH_ERR_ALLOC_FAIL; 309 goto out; 310 } 311 if ((key->sk_application = strdup(application)) == NULL) { 312 error_f("strdup application failed"); 313 r = SSH_ERR_ALLOC_FAIL; 314 goto out; 315 } 316 if ((r = sshbuf_put(key->sk_key_handle, resp->key_handle, 317 resp->key_handle_len)) != 0) { 318 error_fr(r, "put key handle"); 319 goto out; 320 } 321 /* success */ 322 r = 0; 323 *keyp = key; 324 key = NULL; 325 out: 326 sshkey_free(key); 327 return r; 328 } 329 330 static int 331 skerr_to_ssherr(int skerr) 332 { 333 switch (skerr) { 334 case SSH_SK_ERR_UNSUPPORTED: 335 return SSH_ERR_FEATURE_UNSUPPORTED; 336 case SSH_SK_ERR_PIN_REQUIRED: 337 return SSH_ERR_KEY_WRONG_PASSPHRASE; 338 case SSH_SK_ERR_DEVICE_NOT_FOUND: 339 return SSH_ERR_DEVICE_NOT_FOUND; 340 case SSH_SK_ERR_CREDENTIAL_EXISTS: 341 return SSH_ERR_KEY_BAD_PERMISSIONS; 342 case SSH_SK_ERR_GENERAL: 343 default: 344 return SSH_ERR_INVALID_FORMAT; 345 } 346 } 347 348 static void 349 sshsk_free_options(struct sk_option **opts) 350 { 351 size_t i; 352 353 if (opts == NULL) 354 return; 355 for (i = 0; opts[i] != NULL; i++) { 356 free(opts[i]->name); 357 free(opts[i]->value); 358 free(opts[i]); 359 } 360 free(opts); 361 } 362 363 static int 364 sshsk_add_option(struct sk_option ***optsp, size_t *noptsp, 365 const char *name, const char *value, uint8_t required) 366 { 367 struct sk_option **opts = *optsp; 368 size_t nopts = *noptsp; 369 370 if ((opts = recallocarray(opts, nopts, nopts + 2, /* extra for NULL */ 371 sizeof(*opts))) == NULL) { 372 error_f("array alloc failed"); 373 return SSH_ERR_ALLOC_FAIL; 374 } 375 *optsp = opts; 376 *noptsp = nopts + 1; 377 if ((opts[nopts] = calloc(1, sizeof(**opts))) == NULL) { 378 error_f("alloc failed"); 379 return SSH_ERR_ALLOC_FAIL; 380 } 381 if ((opts[nopts]->name = strdup(name)) == NULL || 382 (opts[nopts]->value = strdup(value)) == NULL) { 383 error_f("alloc failed"); 384 return SSH_ERR_ALLOC_FAIL; 385 } 386 opts[nopts]->required = required; 387 return 0; 388 } 389 390 static int 391 make_options(const char *device, const char *user_id, 392 struct sk_option ***optsp) 393 { 394 struct sk_option **opts = NULL; 395 size_t nopts = 0; 396 int r, ret = SSH_ERR_INTERNAL_ERROR; 397 398 if (device != NULL && 399 (r = sshsk_add_option(&opts, &nopts, "device", device, 0)) != 0) { 400 ret = r; 401 goto out; 402 } 403 if (user_id != NULL && 404 (r = sshsk_add_option(&opts, &nopts, "user", user_id, 0)) != 0) { 405 ret = r; 406 goto out; 407 } 408 /* success */ 409 *optsp = opts; 410 opts = NULL; 411 nopts = 0; 412 ret = 0; 413 out: 414 sshsk_free_options(opts); 415 return ret; 416 } 417 418 419 static int 420 fill_attestation_blob(const struct sk_enroll_response *resp, 421 struct sshbuf *attest) 422 { 423 int r; 424 425 if (attest == NULL) 426 return 0; /* nothing to do */ 427 if ((r = sshbuf_put_cstring(attest, "ssh-sk-attest-v01")) != 0 || 428 (r = sshbuf_put_string(attest, 429 resp->attestation_cert, resp->attestation_cert_len)) != 0 || 430 (r = sshbuf_put_string(attest, 431 resp->signature, resp->signature_len)) != 0 || 432 (r = sshbuf_put_string(attest, 433 resp->authdata, resp->authdata_len)) != 0 || 434 (r = sshbuf_put_u32(attest, 0)) != 0 || /* resvd flags */ 435 (r = sshbuf_put_string(attest, NULL, 0)) != 0 /* resvd */) { 436 error_fr(r, "compose"); 437 return r; 438 } 439 /* success */ 440 return 0; 441 } 442 443 int 444 sshsk_enroll(int type, const char *provider_path, const char *device, 445 const char *application, const char *userid, uint8_t flags, 446 const char *pin, struct sshbuf *challenge_buf, 447 struct sshkey **keyp, struct sshbuf *attest) 448 { 449 struct sshsk_provider *skp = NULL; 450 struct sshkey *key = NULL; 451 u_char randchall[32]; 452 const u_char *challenge; 453 size_t challenge_len; 454 struct sk_enroll_response *resp = NULL; 455 struct sk_option **opts = NULL; 456 int r = SSH_ERR_INTERNAL_ERROR; 457 int alg; 458 459 debug_f("provider \"%s\", device \"%s\", application \"%s\", " 460 "userid \"%s\", flags 0x%02x, challenge len %zu%s", 461 provider_path, device, application, userid, flags, 462 challenge_buf == NULL ? 0 : sshbuf_len(challenge_buf), 463 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 464 465 *keyp = NULL; 466 if (attest) 467 sshbuf_reset(attest); 468 469 if ((r = make_options(device, userid, &opts)) != 0) 470 goto out; 471 472 switch (type) { 473 #ifdef WITH_OPENSSL 474 case KEY_ECDSA_SK: 475 alg = SSH_SK_ECDSA; 476 break; 477 #endif /* WITH_OPENSSL */ 478 case KEY_ED25519_SK: 479 alg = SSH_SK_ED25519; 480 break; 481 default: 482 error_f("unsupported key type"); 483 r = SSH_ERR_INVALID_ARGUMENT; 484 goto out; 485 } 486 if (provider_path == NULL) { 487 error_f("missing provider"); 488 r = SSH_ERR_INVALID_ARGUMENT; 489 goto out; 490 } 491 if (application == NULL || *application == '\0') { 492 error_f("missing application"); 493 r = SSH_ERR_INVALID_ARGUMENT; 494 goto out; 495 } 496 if (challenge_buf == NULL) { 497 debug_f("using random challenge"); 498 arc4random_buf(randchall, sizeof(randchall)); 499 challenge = randchall; 500 challenge_len = sizeof(randchall); 501 } else if (sshbuf_len(challenge_buf) == 0) { 502 error("Missing enrollment challenge"); 503 r = SSH_ERR_INVALID_ARGUMENT; 504 goto out; 505 } else { 506 challenge = sshbuf_ptr(challenge_buf); 507 challenge_len = sshbuf_len(challenge_buf); 508 debug3_f("using explicit challenge len=%zd", challenge_len); 509 } 510 if ((skp = sshsk_open(provider_path)) == NULL) { 511 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 512 goto out; 513 } 514 /* XXX validate flags? */ 515 /* enroll key */ 516 if ((r = skp->sk_enroll(alg, challenge, challenge_len, application, 517 flags, pin, opts, &resp)) != 0) { 518 debug_f("provider \"%s\" failure %d", provider_path, r); 519 r = skerr_to_ssherr(r); 520 goto out; 521 } 522 523 if ((r = sshsk_key_from_response(alg, application, resp->flags, 524 resp, &key)) != 0) 525 goto out; 526 527 /* Optionally fill in the attestation information */ 528 if ((r = fill_attestation_blob(resp, attest)) != 0) 529 goto out; 530 531 /* success */ 532 *keyp = key; 533 key = NULL; /* transferred */ 534 r = 0; 535 out: 536 sshsk_free_options(opts); 537 sshsk_free(skp); 538 sshkey_free(key); 539 sshsk_free_enroll_response(resp); 540 explicit_bzero(randchall, sizeof(randchall)); 541 return r; 542 } 543 544 #ifdef WITH_OPENSSL 545 static int 546 sshsk_ecdsa_sig(struct sk_sign_response *resp, struct sshbuf *sig) 547 { 548 struct sshbuf *inner_sig = NULL; 549 int r = SSH_ERR_INTERNAL_ERROR; 550 551 /* Check response validity */ 552 if (resp->sig_r == NULL || resp->sig_s == NULL) { 553 error_f("sk_sign response invalid"); 554 r = SSH_ERR_INVALID_FORMAT; 555 goto out; 556 } 557 if ((inner_sig = sshbuf_new()) == NULL) { 558 r = SSH_ERR_ALLOC_FAIL; 559 goto out; 560 } 561 /* Prepare and append inner signature object */ 562 if ((r = sshbuf_put_bignum2_bytes(inner_sig, 563 resp->sig_r, resp->sig_r_len)) != 0 || 564 (r = sshbuf_put_bignum2_bytes(inner_sig, 565 resp->sig_s, resp->sig_s_len)) != 0) { 566 error_fr(r, "compose inner"); 567 goto out; 568 } 569 if ((r = sshbuf_put_stringb(sig, inner_sig)) != 0 || 570 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 571 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 572 error_fr(r, "compose"); 573 goto out; 574 } 575 #ifdef DEBUG_SK 576 fprintf(stderr, "%s: sig_r:\n", __func__); 577 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 578 fprintf(stderr, "%s: sig_s:\n", __func__); 579 sshbuf_dump_data(resp->sig_s, resp->sig_s_len, stderr); 580 fprintf(stderr, "%s: inner:\n", __func__); 581 sshbuf_dump(inner_sig, stderr); 582 #endif 583 r = 0; 584 out: 585 sshbuf_free(inner_sig); 586 return r; 587 } 588 #endif /* WITH_OPENSSL */ 589 590 static int 591 sshsk_ed25519_sig(struct sk_sign_response *resp, struct sshbuf *sig) 592 { 593 int r = SSH_ERR_INTERNAL_ERROR; 594 595 /* Check response validity */ 596 if (resp->sig_r == NULL) { 597 error_f("sk_sign response invalid"); 598 r = SSH_ERR_INVALID_FORMAT; 599 goto out; 600 } 601 if ((r = sshbuf_put_string(sig, 602 resp->sig_r, resp->sig_r_len)) != 0 || 603 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 604 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 605 error_fr(r, "compose"); 606 goto out; 607 } 608 #ifdef DEBUG_SK 609 fprintf(stderr, "%s: sig_r:\n", __func__); 610 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 611 #endif 612 r = 0; 613 out: 614 return r; 615 } 616 617 int 618 sshsk_sign(const char *provider_path, struct sshkey *key, 619 u_char **sigp, size_t *lenp, const u_char *data, size_t datalen, 620 u_int compat, const char *pin) 621 { 622 struct sshsk_provider *skp = NULL; 623 int r = SSH_ERR_INTERNAL_ERROR; 624 int type, alg; 625 struct sk_sign_response *resp = NULL; 626 struct sshbuf *inner_sig = NULL, *sig = NULL; 627 struct sk_option **opts = NULL; 628 629 debug_f("provider \"%s\", key %s, flags 0x%02x%s", 630 provider_path, sshkey_type(key), key->sk_flags, 631 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 632 633 if (sigp != NULL) 634 *sigp = NULL; 635 if (lenp != NULL) 636 *lenp = 0; 637 type = sshkey_type_plain(key->type); 638 switch (type) { 639 #ifdef WITH_OPENSSL 640 case KEY_ECDSA_SK: 641 alg = SSH_SK_ECDSA; 642 break; 643 #endif /* WITH_OPENSSL */ 644 case KEY_ED25519_SK: 645 alg = SSH_SK_ED25519; 646 break; 647 default: 648 return SSH_ERR_INVALID_ARGUMENT; 649 } 650 if (provider_path == NULL || 651 key->sk_key_handle == NULL || 652 key->sk_application == NULL || *key->sk_application == '\0') { 653 r = SSH_ERR_INVALID_ARGUMENT; 654 goto out; 655 } 656 if ((skp = sshsk_open(provider_path)) == NULL) { 657 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 658 goto out; 659 } 660 #ifdef DEBUG_SK 661 fprintf(stderr, "%s: sk_flags = 0x%02x, sk_application = \"%s\"\n", 662 __func__, key->sk_flags, key->sk_application); 663 fprintf(stderr, "%s: sk_key_handle:\n", __func__); 664 sshbuf_dump(key->sk_key_handle, stderr); 665 #endif 666 if ((r = skp->sk_sign(alg, data, datalen, key->sk_application, 667 sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle), 668 key->sk_flags, pin, opts, &resp)) != 0) { 669 debug_f("sk_sign failed with code %d", r); 670 r = skerr_to_ssherr(r); 671 goto out; 672 } 673 /* Assemble signature */ 674 if ((sig = sshbuf_new()) == NULL) { 675 r = SSH_ERR_ALLOC_FAIL; 676 goto out; 677 } 678 if ((r = sshbuf_put_cstring(sig, sshkey_ssh_name_plain(key))) != 0) { 679 error_fr(r, "compose outer"); 680 goto out; 681 } 682 switch (type) { 683 #ifdef WITH_OPENSSL 684 case KEY_ECDSA_SK: 685 if ((r = sshsk_ecdsa_sig(resp, sig)) != 0) 686 goto out; 687 break; 688 #endif /* WITH_OPENSSL */ 689 case KEY_ED25519_SK: 690 if ((r = sshsk_ed25519_sig(resp, sig)) != 0) 691 goto out; 692 break; 693 } 694 #ifdef DEBUG_SK 695 fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n", 696 __func__, resp->flags, resp->counter); 697 fprintf(stderr, "%s: data to sign:\n", __func__); 698 sshbuf_dump_data(data, datalen, stderr); 699 fprintf(stderr, "%s: sigbuf:\n", __func__); 700 sshbuf_dump(sig, stderr); 701 #endif 702 if (sigp != NULL) { 703 if ((*sigp = malloc(sshbuf_len(sig))) == NULL) { 704 r = SSH_ERR_ALLOC_FAIL; 705 goto out; 706 } 707 memcpy(*sigp, sshbuf_ptr(sig), sshbuf_len(sig)); 708 } 709 if (lenp != NULL) 710 *lenp = sshbuf_len(sig); 711 /* success */ 712 r = 0; 713 out: 714 sshsk_free_options(opts); 715 sshsk_free(skp); 716 sshsk_free_sign_response(resp); 717 sshbuf_free(sig); 718 sshbuf_free(inner_sig); 719 return r; 720 } 721 722 static void 723 sshsk_free_sk_resident_keys(struct sk_resident_key **rks, size_t nrks) 724 { 725 size_t i; 726 727 if (nrks == 0 || rks == NULL) 728 return; 729 for (i = 0; i < nrks; i++) { 730 free(rks[i]->application); 731 freezero(rks[i]->user_id, rks[i]->user_id_len); 732 freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len); 733 freezero(rks[i]->key.public_key, rks[i]->key.public_key_len); 734 freezero(rks[i]->key.signature, rks[i]->key.signature_len); 735 freezero(rks[i]->key.attestation_cert, 736 rks[i]->key.attestation_cert_len); 737 freezero(rks[i], sizeof(**rks)); 738 } 739 free(rks); 740 } 741 742 static void 743 sshsk_free_resident_key(struct sshsk_resident_key *srk) 744 { 745 if (srk == NULL) 746 return; 747 sshkey_free(srk->key); 748 freezero(srk->user_id, srk->user_id_len); 749 free(srk); 750 } 751 752 753 void 754 sshsk_free_resident_keys(struct sshsk_resident_key **srks, size_t nsrks) 755 { 756 size_t i; 757 758 if (srks == NULL || nsrks == 0) 759 return; 760 761 for (i = 0; i < nsrks; i++) 762 sshsk_free_resident_key(srks[i]); 763 free(srks); 764 } 765 766 int 767 sshsk_load_resident(const char *provider_path, const char *device, 768 const char *pin, u_int flags, struct sshsk_resident_key ***srksp, 769 size_t *nsrksp) 770 { 771 struct sshsk_provider *skp = NULL; 772 int r = SSH_ERR_INTERNAL_ERROR; 773 struct sk_resident_key **rks = NULL; 774 size_t i, nrks = 0, nsrks = 0; 775 struct sshkey *key = NULL; 776 struct sshsk_resident_key *srk = NULL, **srks = NULL, **tmp; 777 uint8_t sk_flags; 778 struct sk_option **opts = NULL; 779 780 debug_f("provider \"%s\"%s", provider_path, 781 (pin != NULL && *pin != '\0') ? ", have-pin": ""); 782 783 if (srksp == NULL || nsrksp == NULL) 784 return SSH_ERR_INVALID_ARGUMENT; 785 *srksp = NULL; 786 *nsrksp = 0; 787 788 if ((r = make_options(device, NULL, &opts)) != 0) 789 goto out; 790 if ((skp = sshsk_open(provider_path)) == NULL) { 791 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 792 goto out; 793 } 794 if ((r = skp->sk_load_resident_keys(pin, opts, &rks, &nrks)) != 0) { 795 error("Provider \"%s\" returned failure %d", provider_path, r); 796 r = skerr_to_ssherr(r); 797 goto out; 798 } 799 for (i = 0; i < nrks; i++) { 800 debug3_f("rk %zu: slot %zu, alg %d, app \"%s\", uidlen %zu", 801 i, rks[i]->slot, rks[i]->alg, rks[i]->application, 802 rks[i]->user_id_len); 803 /* XXX need better filter here */ 804 if (strncmp(rks[i]->application, "ssh:", 4) != 0) 805 continue; 806 switch (rks[i]->alg) { 807 case SSH_SK_ECDSA: 808 case SSH_SK_ED25519: 809 break; 810 default: 811 continue; 812 } 813 sk_flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY; 814 if ((rks[i]->flags & SSH_SK_USER_VERIFICATION_REQD)) 815 sk_flags |= SSH_SK_USER_VERIFICATION_REQD; 816 if ((r = sshsk_key_from_response(rks[i]->alg, 817 rks[i]->application, sk_flags, &rks[i]->key, &key)) != 0) 818 goto out; 819 if ((srk = calloc(1, sizeof(*srk))) == NULL) { 820 error_f("calloc failed"); 821 r = SSH_ERR_ALLOC_FAIL; 822 goto out; 823 } 824 srk->key = key; 825 key = NULL; /* transferred */ 826 if ((srk->user_id = calloc(1, rks[i]->user_id_len)) == NULL) { 827 error_f("calloc failed"); 828 r = SSH_ERR_ALLOC_FAIL; 829 goto out; 830 } 831 memcpy(srk->user_id, rks[i]->user_id, rks[i]->user_id_len); 832 srk->user_id_len = rks[i]->user_id_len; 833 if ((tmp = recallocarray(srks, nsrks, nsrks + 1, 834 sizeof(*tmp))) == NULL) { 835 error_f("recallocarray failed"); 836 r = SSH_ERR_ALLOC_FAIL; 837 goto out; 838 } 839 srks = tmp; 840 srks[nsrks++] = srk; 841 srk = NULL; 842 /* XXX synthesise comment */ 843 } 844 /* success */ 845 *srksp = srks; 846 *nsrksp = nsrks; 847 srks = NULL; 848 nsrks = 0; 849 r = 0; 850 out: 851 sshsk_free_options(opts); 852 sshsk_free(skp); 853 sshsk_free_sk_resident_keys(rks, nrks); 854 sshkey_free(key); 855 sshsk_free_resident_key(srk); 856 sshsk_free_resident_keys(srks, nsrks); 857 return r; 858 } 859 860
Indexes created Mon Mar 16 00:23:04 UTC 2026