ssh-sk.c revision 1.7
1 /* $NetBSD: ssh-sk.c,v 1.7 2022/10/05 22:39:36 christos Exp $ */ 2 /* $OpenBSD: ssh-sk.c,v 1.39 2022/07/20 03:29:14 djm Exp $ */ 3 4 /* 5 * Copyright (c) 2019 Google LLC 6 * 7 * Permission to use, copy, modify, and distribute this software for any 8 * purpose with or without fee is hereby granted, provided that the above 9 * copyright notice and this permission notice appear in all copies. 10 * 11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 18 */ 19 #include "includes.h" 20 __RCSID("$NetBSD: ssh-sk.c,v 1.7 2022/10/05 22:39:36 christos Exp $"); 21 22 /* #define DEBUG_SK 1 */ 23 24 #include <dlfcn.h> 25 #include <stddef.h> 26 #include <stdint.h> 27 #include <string.h> 28 #include <stdio.h> 29 30 #ifdef WITH_OPENSSL 31 #include <openssl/objects.h> 32 #include <openssl/ec.h> 33 #endif /* WITH_OPENSSL */ 34 35 #include "log.h" 36 #include "misc.h" 37 #include "sshbuf.h" 38 #include "sshkey.h" 39 #include "ssherr.h" 40 #include "digest.h" 41 42 #include "ssh-sk.h" 43 #include "sk-api.h" 44 #include "crypto_api.h" 45 46 struct sshsk_provider { 47 char *path; 48 void *dlhandle; 49 50 /* Return the version of the middleware API */ 51 uint32_t (*sk_api_version)(void); 52 53 /* Enroll a U2F key (private key generation) */ 54 int (*sk_enroll)(int alg, const uint8_t *challenge, 55 size_t challenge_len, const char *application, uint8_t flags, 56 const char *pin, struct sk_option **opts, 57 struct sk_enroll_response **enroll_response); 58 59 /* Sign a challenge */ 60 int (*sk_sign)(int alg, const uint8_t *message, size_t message_len, 61 const char *application, 62 const uint8_t *key_handle, size_t key_handle_len, 63 uint8_t flags, const char *pin, struct sk_option **opts, 64 struct sk_sign_response **sign_response); 65 66 /* Enumerate resident keys */ 67 int (*sk_load_resident_keys)(const char *pin, struct sk_option **opts, 68 struct sk_resident_key ***rks, size_t *nrks); 69 }; 70 71 /* Built-in version */ 72 int ssh_sk_enroll(int alg, const uint8_t *challenge, 73 size_t challenge_len, const char *application, uint8_t flags, 74 const char *pin, struct sk_option **opts, 75 struct sk_enroll_response **enroll_response); 76 int ssh_sk_sign(int alg, const uint8_t *message, size_t message_len, 77 const char *application, 78 const uint8_t *key_handle, size_t key_handle_len, 79 uint8_t flags, const char *pin, struct sk_option **opts, 80 struct sk_sign_response **sign_response); 81 int ssh_sk_load_resident_keys(const char *pin, struct sk_option **opts, 82 struct sk_resident_key ***rks, size_t *nrks); 83 84 static void 85 sshsk_free(struct sshsk_provider *p) 86 { 87 if (p == NULL) 88 return; 89 free(p->path); 90 if (p->dlhandle != NULL) 91 dlclose(p->dlhandle); 92 free(p); 93 } 94 95 static struct sshsk_provider * 96 sshsk_open(const char *path) 97 { 98 struct sshsk_provider *ret = NULL; 99 uint32_t version; 100 101 if (path == NULL || *path == '\0') { 102 error("No FIDO SecurityKeyProvider specified"); 103 return NULL; 104 } 105 if ((ret = calloc(1, sizeof(*ret))) == NULL) { 106 error_f("calloc failed"); 107 return NULL; 108 } 109 if ((ret->path = strdup(path)) == NULL) { 110 error_f("strdup failed"); 111 goto fail; 112 } 113 /* Skip the rest if we're using the linked in middleware */ 114 if (strcasecmp(ret->path, "internal") == 0) { 115 ret->sk_enroll = ssh_sk_enroll; 116 ret->sk_sign = ssh_sk_sign; 117 ret->sk_load_resident_keys = ssh_sk_load_resident_keys; 118 return ret; 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 error("Provider \"%s\" dlsym(sk_api_version) failed: %s", 127 path, dlerror()); 128 goto fail; 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_POINT *q = NULL; 193 int r; 194 195 *keyp = NULL; 196 if ((key = sshkey_new(KEY_ECDSA_SK)) == NULL) { 197 error_f("sshkey_new failed"); 198 r = SSH_ERR_ALLOC_FAIL; 199 goto out; 200 } 201 key->ecdsa_nid = NID_X9_62_prime256v1; 202 if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL || 203 (q = EC_POINT_new(EC_KEY_get0_group(key->ecdsa))) == NULL || 204 (b = sshbuf_new()) == NULL) { 205 error_f("allocation failed"); 206 r = SSH_ERR_ALLOC_FAIL; 207 goto out; 208 } 209 if ((r = sshbuf_put_string(b, 210 resp->public_key, resp->public_key_len)) != 0) { 211 error_fr(r, "sshbuf_put_string"); 212 goto out; 213 } 214 if ((r = sshbuf_get_ec(b, q, EC_KEY_get0_group(key->ecdsa))) != 0) { 215 error_fr(r, "parse"); 216 r = SSH_ERR_INVALID_FORMAT; 217 goto out; 218 } 219 if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa), q) != 0) { 220 error("Authenticator returned invalid ECDSA key"); 221 r = SSH_ERR_KEY_INVALID_EC_VALUE; 222 goto out; 223 } 224 if (EC_KEY_set_public_key(key->ecdsa, q) != 1) { 225 /* XXX assume it is a allocation error */ 226 error_f("allocation failed"); 227 r = SSH_ERR_ALLOC_FAIL; 228 goto out; 229 } 230 /* success */ 231 *keyp = key; 232 key = NULL; /* transferred */ 233 r = 0; 234 out: 235 EC_POINT_free(q); 236 sshkey_free(key); 237 sshbuf_free(b); 238 return r; 239 } 240 #endif /* WITH_OPENSSL */ 241 242 static int 243 sshsk_ed25519_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 244 { 245 struct sshkey *key = NULL; 246 int r; 247 248 *keyp = NULL; 249 if (resp->public_key_len != ED25519_PK_SZ) { 250 error_f("invalid size: %zu", resp->public_key_len); 251 r = SSH_ERR_INVALID_FORMAT; 252 goto out; 253 } 254 if ((key = sshkey_new(KEY_ED25519_SK)) == NULL) { 255 error_f("sshkey_new failed"); 256 r = SSH_ERR_ALLOC_FAIL; 257 goto out; 258 } 259 if ((key->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) { 260 error_f("malloc failed"); 261 r = SSH_ERR_ALLOC_FAIL; 262 goto out; 263 } 264 memcpy(key->ed25519_pk, resp->public_key, ED25519_PK_SZ); 265 /* success */ 266 *keyp = key; 267 key = NULL; /* transferred */ 268 r = 0; 269 out: 270 sshkey_free(key); 271 return r; 272 } 273 274 static int 275 sshsk_key_from_response(int alg, const char *application, uint8_t flags, 276 struct sk_enroll_response *resp, struct sshkey **keyp) 277 { 278 struct sshkey *key = NULL; 279 int r = SSH_ERR_INTERNAL_ERROR; 280 281 *keyp = NULL; 282 283 /* Check response validity */ 284 if (resp->public_key == NULL || resp->key_handle == NULL) { 285 error_f("sk_enroll response invalid"); 286 r = SSH_ERR_INVALID_FORMAT; 287 goto out; 288 } 289 switch (alg) { 290 #ifdef WITH_OPENSSL 291 case SSH_SK_ECDSA: 292 if ((r = sshsk_ecdsa_assemble(resp, &key)) != 0) 293 goto out; 294 break; 295 #endif /* WITH_OPENSSL */ 296 case SSH_SK_ED25519: 297 if ((r = sshsk_ed25519_assemble(resp, &key)) != 0) 298 goto out; 299 break; 300 default: 301 error_f("unsupported algorithm %d", alg); 302 r = SSH_ERR_INVALID_ARGUMENT; 303 goto out; 304 } 305 key->sk_flags = flags; 306 if ((key->sk_key_handle = sshbuf_new()) == NULL || 307 (key->sk_reserved = sshbuf_new()) == NULL) { 308 error_f("allocation failed"); 309 r = SSH_ERR_ALLOC_FAIL; 310 goto out; 311 } 312 if ((key->sk_application = strdup(application)) == NULL) { 313 error_f("strdup application failed"); 314 r = SSH_ERR_ALLOC_FAIL; 315 goto out; 316 } 317 if ((r = sshbuf_put(key->sk_key_handle, resp->key_handle, 318 resp->key_handle_len)) != 0) { 319 error_fr(r, "put key handle"); 320 goto out; 321 } 322 /* success */ 323 r = 0; 324 *keyp = key; 325 key = NULL; 326 out: 327 sshkey_free(key); 328 return r; 329 } 330 331 static int 332 skerr_to_ssherr(int skerr) 333 { 334 switch (skerr) { 335 case SSH_SK_ERR_UNSUPPORTED: 336 return SSH_ERR_FEATURE_UNSUPPORTED; 337 case SSH_SK_ERR_PIN_REQUIRED: 338 return SSH_ERR_KEY_WRONG_PASSPHRASE; 339 case SSH_SK_ERR_DEVICE_NOT_FOUND: 340 return SSH_ERR_DEVICE_NOT_FOUND; 341 case SSH_SK_ERR_CREDENTIAL_EXISTS: 342 return SSH_ERR_KEY_BAD_PERMISSIONS; 343 case SSH_SK_ERR_GENERAL: 344 default: 345 return SSH_ERR_INVALID_FORMAT; 346 } 347 } 348 349 static void 350 sshsk_free_options(struct sk_option **opts) 351 { 352 size_t i; 353 354 if (opts == NULL) 355 return; 356 for (i = 0; opts[i] != NULL; i++) { 357 free(opts[i]->name); 358 free(opts[i]->value); 359 free(opts[i]); 360 } 361 free(opts); 362 } 363 364 static int 365 sshsk_add_option(struct sk_option ***optsp, size_t *noptsp, 366 const char *name, const char *value, uint8_t required) 367 { 368 struct sk_option **opts = *optsp; 369 size_t nopts = *noptsp; 370 371 if ((opts = recallocarray(opts, nopts, nopts + 2, /* extra for NULL */ 372 sizeof(*opts))) == NULL) { 373 error_f("array alloc failed"); 374 return SSH_ERR_ALLOC_FAIL; 375 } 376 *optsp = opts; 377 *noptsp = nopts + 1; 378 if ((opts[nopts] = calloc(1, sizeof(**opts))) == NULL) { 379 error_f("alloc failed"); 380 return SSH_ERR_ALLOC_FAIL; 381 } 382 if ((opts[nopts]->name = strdup(name)) == NULL || 383 (opts[nopts]->value = strdup(value)) == NULL) { 384 error_f("alloc failed"); 385 return SSH_ERR_ALLOC_FAIL; 386 } 387 opts[nopts]->required = required; 388 return 0; 389 } 390 391 static int 392 make_options(const char *device, const char *user_id, 393 struct sk_option ***optsp) 394 { 395 struct sk_option **opts = NULL; 396 size_t nopts = 0; 397 int r, ret = SSH_ERR_INTERNAL_ERROR; 398 399 if (device != NULL && 400 (r = sshsk_add_option(&opts, &nopts, "device", device, 0)) != 0) { 401 ret = r; 402 goto out; 403 } 404 if (user_id != NULL && 405 (r = sshsk_add_option(&opts, &nopts, "user", user_id, 0)) != 0) { 406 ret = r; 407 goto out; 408 } 409 /* success */ 410 *optsp = opts; 411 opts = NULL; 412 nopts = 0; 413 ret = 0; 414 out: 415 sshsk_free_options(opts); 416 return ret; 417 } 418 419 420 static int 421 fill_attestation_blob(const struct sk_enroll_response *resp, 422 struct sshbuf *attest) 423 { 424 int r; 425 426 if (attest == NULL) 427 return 0; /* nothing to do */ 428 if ((r = sshbuf_put_cstring(attest, "ssh-sk-attest-v01")) != 0 || 429 (r = sshbuf_put_string(attest, 430 resp->attestation_cert, resp->attestation_cert_len)) != 0 || 431 (r = sshbuf_put_string(attest, 432 resp->signature, resp->signature_len)) != 0 || 433 (r = sshbuf_put_string(attest, 434 resp->authdata, resp->authdata_len)) != 0 || 435 (r = sshbuf_put_u32(attest, 0)) != 0 || /* resvd flags */ 436 (r = sshbuf_put_string(attest, NULL, 0)) != 0 /* resvd */) { 437 error_fr(r, "compose"); 438 return r; 439 } 440 /* success */ 441 return 0; 442 } 443 444 int 445 sshsk_enroll(int type, const char *provider_path, const char *device, 446 const char *application, const char *userid, uint8_t flags, 447 const char *pin, struct sshbuf *challenge_buf, 448 struct sshkey **keyp, struct sshbuf *attest) 449 { 450 struct sshsk_provider *skp = NULL; 451 struct sshkey *key = NULL; 452 u_char randchall[32]; 453 const u_char *challenge; 454 size_t challenge_len; 455 struct sk_enroll_response *resp = NULL; 456 struct sk_option **opts = NULL; 457 int r = SSH_ERR_INTERNAL_ERROR; 458 int alg; 459 460 debug_f("provider \"%s\", device \"%s\", application \"%s\", " 461 "userid \"%s\", flags 0x%02x, challenge len %zu%s", 462 provider_path, device, application, userid, flags, 463 challenge_buf == NULL ? 0 : sshbuf_len(challenge_buf), 464 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 465 466 *keyp = NULL; 467 if (attest) 468 sshbuf_reset(attest); 469 470 if ((r = make_options(device, userid, &opts)) != 0) 471 goto out; 472 473 switch (type) { 474 #ifdef WITH_OPENSSL 475 case KEY_ECDSA_SK: 476 alg = SSH_SK_ECDSA; 477 break; 478 #endif /* WITH_OPENSSL */ 479 case KEY_ED25519_SK: 480 alg = SSH_SK_ED25519; 481 break; 482 default: 483 error_f("unsupported key type"); 484 r = SSH_ERR_INVALID_ARGUMENT; 485 goto out; 486 } 487 if (provider_path == NULL) { 488 error_f("missing provider"); 489 r = SSH_ERR_INVALID_ARGUMENT; 490 goto out; 491 } 492 if (application == NULL || *application == '\0') { 493 error_f("missing application"); 494 r = SSH_ERR_INVALID_ARGUMENT; 495 goto out; 496 } 497 if (challenge_buf == NULL) { 498 debug_f("using random challenge"); 499 arc4random_buf(randchall, sizeof(randchall)); 500 challenge = randchall; 501 challenge_len = sizeof(randchall); 502 } else if (sshbuf_len(challenge_buf) == 0) { 503 error("Missing enrollment challenge"); 504 r = SSH_ERR_INVALID_ARGUMENT; 505 goto out; 506 } else { 507 challenge = sshbuf_ptr(challenge_buf); 508 challenge_len = sshbuf_len(challenge_buf); 509 debug3_f("using explicit challenge len=%zd", challenge_len); 510 } 511 if ((skp = sshsk_open(provider_path)) == NULL) { 512 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 513 goto out; 514 } 515 /* XXX validate flags? */ 516 /* enroll key */ 517 if ((r = skp->sk_enroll(alg, challenge, challenge_len, application, 518 flags, pin, opts, &resp)) != 0) { 519 debug_f("provider \"%s\" failure %d", provider_path, r); 520 r = skerr_to_ssherr(r); 521 goto out; 522 } 523 524 if ((r = sshsk_key_from_response(alg, application, resp->flags, 525 resp, &key)) != 0) 526 goto out; 527 528 /* Optionally fill in the attestation information */ 529 if ((r = fill_attestation_blob(resp, attest)) != 0) 530 goto out; 531 532 /* success */ 533 *keyp = key; 534 key = NULL; /* transferred */ 535 r = 0; 536 out: 537 sshsk_free_options(opts); 538 sshsk_free(skp); 539 sshkey_free(key); 540 sshsk_free_enroll_response(resp); 541 explicit_bzero(randchall, sizeof(randchall)); 542 return r; 543 } 544 545 #ifdef WITH_OPENSSL 546 static int 547 sshsk_ecdsa_sig(struct sk_sign_response *resp, struct sshbuf *sig) 548 { 549 struct sshbuf *inner_sig = NULL; 550 int r = SSH_ERR_INTERNAL_ERROR; 551 552 /* Check response validity */ 553 if (resp->sig_r == NULL || resp->sig_s == NULL) { 554 error_f("sk_sign response invalid"); 555 r = SSH_ERR_INVALID_FORMAT; 556 goto out; 557 } 558 if ((inner_sig = sshbuf_new()) == NULL) { 559 r = SSH_ERR_ALLOC_FAIL; 560 goto out; 561 } 562 /* Prepare and append inner signature object */ 563 if ((r = sshbuf_put_bignum2_bytes(inner_sig, 564 resp->sig_r, resp->sig_r_len)) != 0 || 565 (r = sshbuf_put_bignum2_bytes(inner_sig, 566 resp->sig_s, resp->sig_s_len)) != 0) { 567 error_fr(r, "compose inner"); 568 goto out; 569 } 570 if ((r = sshbuf_put_stringb(sig, inner_sig)) != 0 || 571 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 572 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 573 error_fr(r, "compose"); 574 goto out; 575 } 576 #ifdef DEBUG_SK 577 fprintf(stderr, "%s: sig_r:\n", __func__); 578 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 579 fprintf(stderr, "%s: sig_s:\n", __func__); 580 sshbuf_dump_data(resp->sig_s, resp->sig_s_len, stderr); 581 fprintf(stderr, "%s: inner:\n", __func__); 582 sshbuf_dump(inner_sig, stderr); 583 #endif 584 r = 0; 585 out: 586 sshbuf_free(inner_sig); 587 return r; 588 } 589 #endif /* WITH_OPENSSL */ 590 591 static int 592 sshsk_ed25519_sig(struct sk_sign_response *resp, struct sshbuf *sig) 593 { 594 int r = SSH_ERR_INTERNAL_ERROR; 595 596 /* Check response validity */ 597 if (resp->sig_r == NULL) { 598 error_f("sk_sign response invalid"); 599 r = SSH_ERR_INVALID_FORMAT; 600 goto out; 601 } 602 if ((r = sshbuf_put_string(sig, 603 resp->sig_r, resp->sig_r_len)) != 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 #endif 613 r = 0; 614 out: 615 return r; 616 } 617 618 int 619 sshsk_sign(const char *provider_path, struct sshkey *key, 620 u_char **sigp, size_t *lenp, const u_char *data, size_t datalen, 621 u_int compat, const char *pin) 622 { 623 struct sshsk_provider *skp = NULL; 624 int r = SSH_ERR_INTERNAL_ERROR; 625 int type, alg; 626 struct sk_sign_response *resp = NULL; 627 struct sshbuf *inner_sig = NULL, *sig = NULL; 628 struct sk_option **opts = NULL; 629 630 debug_f("provider \"%s\", key %s, flags 0x%02x%s", 631 provider_path, sshkey_type(key), key->sk_flags, 632 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 633 634 if (sigp != NULL) 635 *sigp = NULL; 636 if (lenp != NULL) 637 *lenp = 0; 638 type = sshkey_type_plain(key->type); 639 switch (type) { 640 #ifdef WITH_OPENSSL 641 case KEY_ECDSA_SK: 642 alg = SSH_SK_ECDSA; 643 break; 644 #endif /* WITH_OPENSSL */ 645 case KEY_ED25519_SK: 646 alg = SSH_SK_ED25519; 647 break; 648 default: 649 return SSH_ERR_INVALID_ARGUMENT; 650 } 651 if (provider_path == NULL || 652 key->sk_key_handle == NULL || 653 key->sk_application == NULL || *key->sk_application == '\0') { 654 r = SSH_ERR_INVALID_ARGUMENT; 655 goto out; 656 } 657 if ((skp = sshsk_open(provider_path)) == NULL) { 658 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 659 goto out; 660 } 661 #ifdef DEBUG_SK 662 fprintf(stderr, "%s: sk_flags = 0x%02x, sk_application = \"%s\"\n", 663 __func__, key->sk_flags, key->sk_application); 664 fprintf(stderr, "%s: sk_key_handle:\n", __func__); 665 sshbuf_dump(key->sk_key_handle, stderr); 666 #endif 667 if ((r = skp->sk_sign(alg, data, datalen, key->sk_application, 668 sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle), 669 key->sk_flags, pin, opts, &resp)) != 0) { 670 debug_f("sk_sign failed with code %d", r); 671 r = skerr_to_ssherr(r); 672 goto out; 673 } 674 /* Assemble signature */ 675 if ((sig = sshbuf_new()) == NULL) { 676 r = SSH_ERR_ALLOC_FAIL; 677 goto out; 678 } 679 if ((r = sshbuf_put_cstring(sig, sshkey_ssh_name_plain(key))) != 0) { 680 error_fr(r, "compose outer"); 681 goto out; 682 } 683 switch (type) { 684 #ifdef WITH_OPENSSL 685 case KEY_ECDSA_SK: 686 if ((r = sshsk_ecdsa_sig(resp, sig)) != 0) 687 goto out; 688 break; 689 #endif /* WITH_OPENSSL */ 690 case KEY_ED25519_SK: 691 if ((r = sshsk_ed25519_sig(resp, sig)) != 0) 692 goto out; 693 break; 694 } 695 #ifdef DEBUG_SK 696 fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n", 697 __func__, resp->flags, resp->counter); 698 fprintf(stderr, "%s: data to sign:\n", __func__); 699 sshbuf_dump_data(data, datalen, stderr); 700 fprintf(stderr, "%s: sigbuf:\n", __func__); 701 sshbuf_dump(sig, stderr); 702 #endif 703 if (sigp != NULL) { 704 if ((*sigp = malloc(sshbuf_len(sig))) == NULL) { 705 r = SSH_ERR_ALLOC_FAIL; 706 goto out; 707 } 708 memcpy(*sigp, sshbuf_ptr(sig), sshbuf_len(sig)); 709 } 710 if (lenp != NULL) 711 *lenp = sshbuf_len(sig); 712 /* success */ 713 r = 0; 714 out: 715 sshsk_free_options(opts); 716 sshsk_free(skp); 717 sshsk_free_sign_response(resp); 718 sshbuf_free(sig); 719 sshbuf_free(inner_sig); 720 return r; 721 } 722 723 static void 724 sshsk_free_sk_resident_keys(struct sk_resident_key **rks, size_t nrks) 725 { 726 size_t i; 727 728 if (nrks == 0 || rks == NULL) 729 return; 730 for (i = 0; i < nrks; i++) { 731 free(rks[i]->application); 732 freezero(rks[i]->user_id, rks[i]->user_id_len); 733 freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len); 734 freezero(rks[i]->key.public_key, rks[i]->key.public_key_len); 735 freezero(rks[i]->key.signature, rks[i]->key.signature_len); 736 freezero(rks[i]->key.attestation_cert, 737 rks[i]->key.attestation_cert_len); 738 freezero(rks[i], sizeof(**rks)); 739 } 740 free(rks); 741 } 742 743 static void 744 sshsk_free_resident_key(struct sshsk_resident_key *srk) 745 { 746 if (srk == NULL) 747 return; 748 sshkey_free(srk->key); 749 freezero(srk->user_id, srk->user_id_len); 750 free(srk); 751 } 752 753 754 void 755 sshsk_free_resident_keys(struct sshsk_resident_key **srks, size_t nsrks) 756 { 757 size_t i; 758 759 if (srks == NULL || nsrks == 0) 760 return; 761 762 for (i = 0; i < nsrks; i++) 763 sshsk_free_resident_key(srks[i]); 764 free(srks); 765 } 766 767 int 768 sshsk_load_resident(const char *provider_path, const char *device, 769 const char *pin, u_int flags, struct sshsk_resident_key ***srksp, 770 size_t *nsrksp) 771 { 772 struct sshsk_provider *skp = NULL; 773 int r = SSH_ERR_INTERNAL_ERROR; 774 struct sk_resident_key **rks = NULL; 775 size_t i, nrks = 0, nsrks = 0; 776 struct sshkey *key = NULL; 777 struct sshsk_resident_key *srk = NULL, **srks = NULL, **tmp; 778 uint8_t sk_flags; 779 struct sk_option **opts = NULL; 780 781 debug_f("provider \"%s\"%s", provider_path, 782 (pin != NULL && *pin != '\0') ? ", have-pin": ""); 783 784 if (srksp == NULL || nsrksp == NULL) 785 return SSH_ERR_INVALID_ARGUMENT; 786 *srksp = NULL; 787 *nsrksp = 0; 788 789 if ((r = make_options(device, NULL, &opts)) != 0) 790 goto out; 791 if ((skp = sshsk_open(provider_path)) == NULL) { 792 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 793 goto out; 794 } 795 if ((r = skp->sk_load_resident_keys(pin, opts, &rks, &nrks)) != 0) { 796 error("Provider \"%s\" returned failure %d", provider_path, r); 797 r = skerr_to_ssherr(r); 798 goto out; 799 } 800 for (i = 0; i < nrks; i++) { 801 debug3_f("rk %zu: slot %zu, alg %d, app \"%s\", uidlen %zu", 802 i, rks[i]->slot, rks[i]->alg, rks[i]->application, 803 rks[i]->user_id_len); 804 /* XXX need better filter here */ 805 if (strncmp(rks[i]->application, "ssh:", 4) != 0) 806 continue; 807 switch (rks[i]->alg) { 808 case SSH_SK_ECDSA: 809 case SSH_SK_ED25519: 810 break; 811 default: 812 continue; 813 } 814 sk_flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY; 815 if ((rks[i]->flags & SSH_SK_USER_VERIFICATION_REQD)) 816 sk_flags |= SSH_SK_USER_VERIFICATION_REQD; 817 if ((r = sshsk_key_from_response(rks[i]->alg, 818 rks[i]->application, sk_flags, &rks[i]->key, &key)) != 0) 819 goto out; 820 if ((srk = calloc(1, sizeof(*srk))) == NULL) { 821 error_f("calloc failed"); 822 r = SSH_ERR_ALLOC_FAIL; 823 goto out; 824 } 825 srk->key = key; 826 key = NULL; /* transferred */ 827 if ((srk->user_id = calloc(1, rks[i]->user_id_len)) == NULL) { 828 error_f("calloc failed"); 829 r = SSH_ERR_ALLOC_FAIL; 830 goto out; 831 } 832 memcpy(srk->user_id, rks[i]->user_id, rks[i]->user_id_len); 833 srk->user_id_len = rks[i]->user_id_len; 834 if ((tmp = recallocarray(srks, nsrks, nsrks + 1, 835 sizeof(*tmp))) == NULL) { 836 error_f("recallocarray failed"); 837 r = SSH_ERR_ALLOC_FAIL; 838 goto out; 839 } 840 srks = tmp; 841 srks[nsrks++] = srk; 842 srk = NULL; 843 /* XXX synthesise comment */ 844 } 845 /* success */ 846 *srksp = srks; 847 *nsrksp = nsrks; 848 srks = NULL; 849 nsrks = 0; 850 r = 0; 851 out: 852 sshsk_free_options(opts); 853 sshsk_free(skp); 854 sshsk_free_sk_resident_keys(rks, nrks); 855 sshkey_free(key); 856 sshsk_free_resident_key(srk); 857 sshsk_free_resident_keys(srks, nsrks); 858 return r; 859 } 860 861
Indexes created Mon Mar 16 00:23:04 UTC 2026