ssh-sk.c revision 1.7.2.1
1 /* $NetBSD: ssh-sk.c,v 1.7.2.1 2023/11/02 22:15:22 sborrill Exp $ */ 2 /* $OpenBSD: ssh-sk.c,v 1.40 2023/07/19 14:02:27 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 1.7.2.1 2023/11/02 22:15:22 sborrill 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 (lib_contains_symbol(path, "sk_api_version") != 0) { 121 error("provider %s is not an OpenSSH FIDO library", path); 122 goto fail; 123 } 124 if ((ret->dlhandle = dlopen(path, RTLD_NOW)) == NULL) { 125 error("Provider \"%s\" dlopen failed: %s", path, dlerror()); 126 goto fail; 127 } 128 if ((ret->sk_api_version = dlsym(ret->dlhandle, 129 "sk_api_version")) == NULL) { 130 fatal("Provider \"%s\" dlsym(sk_api_version) failed: %s", 131 path, dlerror()); 132 } 133 version = ret->sk_api_version(); 134 debug_f("provider %s implements version 0x%08lx", ret->path, 135 (u_long)version); 136 if ((version & SSH_SK_VERSION_MAJOR_MASK) != SSH_SK_VERSION_MAJOR) { 137 error("Provider \"%s\" implements unsupported " 138 "version 0x%08lx (supported: 0x%08lx)", 139 path, (u_long)version, (u_long)SSH_SK_VERSION_MAJOR); 140 goto fail; 141 } 142 if ((ret->sk_enroll = dlsym(ret->dlhandle, "sk_enroll")) == NULL) { 143 error("Provider %s dlsym(sk_enroll) failed: %s", 144 path, dlerror()); 145 goto fail; 146 } 147 if ((ret->sk_sign = dlsym(ret->dlhandle, "sk_sign")) == NULL) { 148 error("Provider \"%s\" dlsym(sk_sign) failed: %s", 149 path, dlerror()); 150 goto fail; 151 } 152 if ((ret->sk_load_resident_keys = dlsym(ret->dlhandle, 153 "sk_load_resident_keys")) == NULL) { 154 error("Provider \"%s\" dlsym(sk_load_resident_keys) " 155 "failed: %s", path, dlerror()); 156 goto fail; 157 } 158 /* success */ 159 return ret; 160 fail: 161 sshsk_free(ret); 162 return NULL; 163 } 164 165 static void 166 sshsk_free_enroll_response(struct sk_enroll_response *r) 167 { 168 if (r == NULL) 169 return; 170 freezero(r->key_handle, r->key_handle_len); 171 freezero(r->public_key, r->public_key_len); 172 freezero(r->signature, r->signature_len); 173 freezero(r->attestation_cert, r->attestation_cert_len); 174 freezero(r->authdata, r->authdata_len); 175 freezero(r, sizeof(*r)); 176 } 177 178 static void 179 sshsk_free_sign_response(struct sk_sign_response *r) 180 { 181 if (r == NULL) 182 return; 183 freezero(r->sig_r, r->sig_r_len); 184 freezero(r->sig_s, r->sig_s_len); 185 freezero(r, sizeof(*r)); 186 } 187 188 #ifdef WITH_OPENSSL 189 /* Assemble key from response */ 190 static int 191 sshsk_ecdsa_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 192 { 193 struct sshkey *key = NULL; 194 struct sshbuf *b = NULL; 195 EC_POINT *q = NULL; 196 int r; 197 198 *keyp = NULL; 199 if ((key = sshkey_new(KEY_ECDSA_SK)) == NULL) { 200 error_f("sshkey_new failed"); 201 r = SSH_ERR_ALLOC_FAIL; 202 goto out; 203 } 204 key->ecdsa_nid = NID_X9_62_prime256v1; 205 if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL || 206 (q = EC_POINT_new(EC_KEY_get0_group(key->ecdsa))) == 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, EC_KEY_get0_group(key->ecdsa))) != 0) { 218 error_fr(r, "parse"); 219 r = SSH_ERR_INVALID_FORMAT; 220 goto out; 221 } 222 if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa), 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(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 /* success */ 234 *keyp = key; 235 key = NULL; /* transferred */ 236 r = 0; 237 out: 238 EC_POINT_free(q); 239 sshkey_free(key); 240 sshbuf_free(b); 241 return r; 242 } 243 #endif /* WITH_OPENSSL */ 244 245 static int 246 sshsk_ed25519_assemble(struct sk_enroll_response *resp, struct sshkey **keyp) 247 { 248 struct sshkey *key = NULL; 249 int r; 250 251 *keyp = NULL; 252 if (resp->public_key_len != ED25519_PK_SZ) { 253 error_f("invalid size: %zu", resp->public_key_len); 254 r = SSH_ERR_INVALID_FORMAT; 255 goto out; 256 } 257 if ((key = sshkey_new(KEY_ED25519_SK)) == NULL) { 258 error_f("sshkey_new failed"); 259 r = SSH_ERR_ALLOC_FAIL; 260 goto out; 261 } 262 if ((key->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) { 263 error_f("malloc failed"); 264 r = SSH_ERR_ALLOC_FAIL; 265 goto out; 266 } 267 memcpy(key->ed25519_pk, resp->public_key, ED25519_PK_SZ); 268 /* success */ 269 *keyp = key; 270 key = NULL; /* transferred */ 271 r = 0; 272 out: 273 sshkey_free(key); 274 return r; 275 } 276 277 static int 278 sshsk_key_from_response(int alg, const char *application, uint8_t flags, 279 struct sk_enroll_response *resp, struct sshkey **keyp) 280 { 281 struct sshkey *key = NULL; 282 int r = SSH_ERR_INTERNAL_ERROR; 283 284 *keyp = NULL; 285 286 /* Check response validity */ 287 if (resp->public_key == NULL || resp->key_handle == NULL) { 288 error_f("sk_enroll response invalid"); 289 r = SSH_ERR_INVALID_FORMAT; 290 goto out; 291 } 292 switch (alg) { 293 #ifdef WITH_OPENSSL 294 case SSH_SK_ECDSA: 295 if ((r = sshsk_ecdsa_assemble(resp, &key)) != 0) 296 goto out; 297 break; 298 #endif /* WITH_OPENSSL */ 299 case SSH_SK_ED25519: 300 if ((r = sshsk_ed25519_assemble(resp, &key)) != 0) 301 goto out; 302 break; 303 default: 304 error_f("unsupported algorithm %d", alg); 305 r = SSH_ERR_INVALID_ARGUMENT; 306 goto out; 307 } 308 key->sk_flags = flags; 309 if ((key->sk_key_handle = sshbuf_new()) == NULL || 310 (key->sk_reserved = sshbuf_new()) == NULL) { 311 error_f("allocation failed"); 312 r = SSH_ERR_ALLOC_FAIL; 313 goto out; 314 } 315 if ((key->sk_application = strdup(application)) == NULL) { 316 error_f("strdup application failed"); 317 r = SSH_ERR_ALLOC_FAIL; 318 goto out; 319 } 320 if ((r = sshbuf_put(key->sk_key_handle, resp->key_handle, 321 resp->key_handle_len)) != 0) { 322 error_fr(r, "put key handle"); 323 goto out; 324 } 325 /* success */ 326 r = 0; 327 *keyp = key; 328 key = NULL; 329 out: 330 sshkey_free(key); 331 return r; 332 } 333 334 static int 335 skerr_to_ssherr(int skerr) 336 { 337 switch (skerr) { 338 case SSH_SK_ERR_UNSUPPORTED: 339 return SSH_ERR_FEATURE_UNSUPPORTED; 340 case SSH_SK_ERR_PIN_REQUIRED: 341 return SSH_ERR_KEY_WRONG_PASSPHRASE; 342 case SSH_SK_ERR_DEVICE_NOT_FOUND: 343 return SSH_ERR_DEVICE_NOT_FOUND; 344 case SSH_SK_ERR_CREDENTIAL_EXISTS: 345 return SSH_ERR_KEY_BAD_PERMISSIONS; 346 case SSH_SK_ERR_GENERAL: 347 default: 348 return SSH_ERR_INVALID_FORMAT; 349 } 350 } 351 352 static void 353 sshsk_free_options(struct sk_option **opts) 354 { 355 size_t i; 356 357 if (opts == NULL) 358 return; 359 for (i = 0; opts[i] != NULL; i++) { 360 free(opts[i]->name); 361 free(opts[i]->value); 362 free(opts[i]); 363 } 364 free(opts); 365 } 366 367 static int 368 sshsk_add_option(struct sk_option ***optsp, size_t *noptsp, 369 const char *name, const char *value, uint8_t required) 370 { 371 struct sk_option **opts = *optsp; 372 size_t nopts = *noptsp; 373 374 if ((opts = recallocarray(opts, nopts, nopts + 2, /* extra for NULL */ 375 sizeof(*opts))) == NULL) { 376 error_f("array alloc failed"); 377 return SSH_ERR_ALLOC_FAIL; 378 } 379 *optsp = opts; 380 *noptsp = nopts + 1; 381 if ((opts[nopts] = calloc(1, sizeof(**opts))) == NULL) { 382 error_f("alloc failed"); 383 return SSH_ERR_ALLOC_FAIL; 384 } 385 if ((opts[nopts]->name = strdup(name)) == NULL || 386 (opts[nopts]->value = strdup(value)) == NULL) { 387 error_f("alloc failed"); 388 return SSH_ERR_ALLOC_FAIL; 389 } 390 opts[nopts]->required = required; 391 return 0; 392 } 393 394 static int 395 make_options(const char *device, const char *user_id, 396 struct sk_option ***optsp) 397 { 398 struct sk_option **opts = NULL; 399 size_t nopts = 0; 400 int r, ret = SSH_ERR_INTERNAL_ERROR; 401 402 if (device != NULL && 403 (r = sshsk_add_option(&opts, &nopts, "device", device, 0)) != 0) { 404 ret = r; 405 goto out; 406 } 407 if (user_id != NULL && 408 (r = sshsk_add_option(&opts, &nopts, "user", user_id, 0)) != 0) { 409 ret = r; 410 goto out; 411 } 412 /* success */ 413 *optsp = opts; 414 opts = NULL; 415 nopts = 0; 416 ret = 0; 417 out: 418 sshsk_free_options(opts); 419 return ret; 420 } 421 422 423 static int 424 fill_attestation_blob(const struct sk_enroll_response *resp, 425 struct sshbuf *attest) 426 { 427 int r; 428 429 if (attest == NULL) 430 return 0; /* nothing to do */ 431 if ((r = sshbuf_put_cstring(attest, "ssh-sk-attest-v01")) != 0 || 432 (r = sshbuf_put_string(attest, 433 resp->attestation_cert, resp->attestation_cert_len)) != 0 || 434 (r = sshbuf_put_string(attest, 435 resp->signature, resp->signature_len)) != 0 || 436 (r = sshbuf_put_string(attest, 437 resp->authdata, resp->authdata_len)) != 0 || 438 (r = sshbuf_put_u32(attest, 0)) != 0 || /* resvd flags */ 439 (r = sshbuf_put_string(attest, NULL, 0)) != 0 /* resvd */) { 440 error_fr(r, "compose"); 441 return r; 442 } 443 /* success */ 444 return 0; 445 } 446 447 int 448 sshsk_enroll(int type, const char *provider_path, const char *device, 449 const char *application, const char *userid, uint8_t flags, 450 const char *pin, struct sshbuf *challenge_buf, 451 struct sshkey **keyp, struct sshbuf *attest) 452 { 453 struct sshsk_provider *skp = NULL; 454 struct sshkey *key = NULL; 455 u_char randchall[32]; 456 const u_char *challenge; 457 size_t challenge_len; 458 struct sk_enroll_response *resp = NULL; 459 struct sk_option **opts = NULL; 460 int r = SSH_ERR_INTERNAL_ERROR; 461 int alg; 462 463 debug_f("provider \"%s\", device \"%s\", application \"%s\", " 464 "userid \"%s\", flags 0x%02x, challenge len %zu%s", 465 provider_path, device, application, userid, flags, 466 challenge_buf == NULL ? 0 : sshbuf_len(challenge_buf), 467 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 468 469 *keyp = NULL; 470 if (attest) 471 sshbuf_reset(attest); 472 473 if ((r = make_options(device, userid, &opts)) != 0) 474 goto out; 475 476 switch (type) { 477 #ifdef WITH_OPENSSL 478 case KEY_ECDSA_SK: 479 alg = SSH_SK_ECDSA; 480 break; 481 #endif /* WITH_OPENSSL */ 482 case KEY_ED25519_SK: 483 alg = SSH_SK_ED25519; 484 break; 485 default: 486 error_f("unsupported key type"); 487 r = SSH_ERR_INVALID_ARGUMENT; 488 goto out; 489 } 490 if (provider_path == NULL) { 491 error_f("missing provider"); 492 r = SSH_ERR_INVALID_ARGUMENT; 493 goto out; 494 } 495 if (application == NULL || *application == '\0') { 496 error_f("missing application"); 497 r = SSH_ERR_INVALID_ARGUMENT; 498 goto out; 499 } 500 if (challenge_buf == NULL) { 501 debug_f("using random challenge"); 502 arc4random_buf(randchall, sizeof(randchall)); 503 challenge = randchall; 504 challenge_len = sizeof(randchall); 505 } else if (sshbuf_len(challenge_buf) == 0) { 506 error("Missing enrollment challenge"); 507 r = SSH_ERR_INVALID_ARGUMENT; 508 goto out; 509 } else { 510 challenge = sshbuf_ptr(challenge_buf); 511 challenge_len = sshbuf_len(challenge_buf); 512 debug3_f("using explicit challenge len=%zd", challenge_len); 513 } 514 if ((skp = sshsk_open(provider_path)) == NULL) { 515 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 516 goto out; 517 } 518 /* XXX validate flags? */ 519 /* enroll key */ 520 if ((r = skp->sk_enroll(alg, challenge, challenge_len, application, 521 flags, pin, opts, &resp)) != 0) { 522 debug_f("provider \"%s\" failure %d", provider_path, r); 523 r = skerr_to_ssherr(r); 524 goto out; 525 } 526 527 if ((r = sshsk_key_from_response(alg, application, resp->flags, 528 resp, &key)) != 0) 529 goto out; 530 531 /* Optionally fill in the attestation information */ 532 if ((r = fill_attestation_blob(resp, attest)) != 0) 533 goto out; 534 535 /* success */ 536 *keyp = key; 537 key = NULL; /* transferred */ 538 r = 0; 539 out: 540 sshsk_free_options(opts); 541 sshsk_free(skp); 542 sshkey_free(key); 543 sshsk_free_enroll_response(resp); 544 explicit_bzero(randchall, sizeof(randchall)); 545 return r; 546 } 547 548 #ifdef WITH_OPENSSL 549 static int 550 sshsk_ecdsa_sig(struct sk_sign_response *resp, struct sshbuf *sig) 551 { 552 struct sshbuf *inner_sig = NULL; 553 int r = SSH_ERR_INTERNAL_ERROR; 554 555 /* Check response validity */ 556 if (resp->sig_r == NULL || resp->sig_s == NULL) { 557 error_f("sk_sign response invalid"); 558 r = SSH_ERR_INVALID_FORMAT; 559 goto out; 560 } 561 if ((inner_sig = sshbuf_new()) == NULL) { 562 r = SSH_ERR_ALLOC_FAIL; 563 goto out; 564 } 565 /* Prepare and append inner signature object */ 566 if ((r = sshbuf_put_bignum2_bytes(inner_sig, 567 resp->sig_r, resp->sig_r_len)) != 0 || 568 (r = sshbuf_put_bignum2_bytes(inner_sig, 569 resp->sig_s, resp->sig_s_len)) != 0) { 570 error_fr(r, "compose inner"); 571 goto out; 572 } 573 if ((r = sshbuf_put_stringb(sig, inner_sig)) != 0 || 574 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 575 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 576 error_fr(r, "compose"); 577 goto out; 578 } 579 #ifdef DEBUG_SK 580 fprintf(stderr, "%s: sig_r:\n", __func__); 581 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 582 fprintf(stderr, "%s: sig_s:\n", __func__); 583 sshbuf_dump_data(resp->sig_s, resp->sig_s_len, stderr); 584 fprintf(stderr, "%s: inner:\n", __func__); 585 sshbuf_dump(inner_sig, stderr); 586 #endif 587 r = 0; 588 out: 589 sshbuf_free(inner_sig); 590 return r; 591 } 592 #endif /* WITH_OPENSSL */ 593 594 static int 595 sshsk_ed25519_sig(struct sk_sign_response *resp, struct sshbuf *sig) 596 { 597 int r = SSH_ERR_INTERNAL_ERROR; 598 599 /* Check response validity */ 600 if (resp->sig_r == NULL) { 601 error_f("sk_sign response invalid"); 602 r = SSH_ERR_INVALID_FORMAT; 603 goto out; 604 } 605 if ((r = sshbuf_put_string(sig, 606 resp->sig_r, resp->sig_r_len)) != 0 || 607 (r = sshbuf_put_u8(sig, resp->flags)) != 0 || 608 (r = sshbuf_put_u32(sig, resp->counter)) != 0) { 609 error_fr(r, "compose"); 610 goto out; 611 } 612 #ifdef DEBUG_SK 613 fprintf(stderr, "%s: sig_r:\n", __func__); 614 sshbuf_dump_data(resp->sig_r, resp->sig_r_len, stderr); 615 #endif 616 r = 0; 617 out: 618 return r; 619 } 620 621 int 622 sshsk_sign(const char *provider_path, struct sshkey *key, 623 u_char **sigp, size_t *lenp, const u_char *data, size_t datalen, 624 u_int compat, const char *pin) 625 { 626 struct sshsk_provider *skp = NULL; 627 int r = SSH_ERR_INTERNAL_ERROR; 628 int type, alg; 629 struct sk_sign_response *resp = NULL; 630 struct sshbuf *inner_sig = NULL, *sig = NULL; 631 struct sk_option **opts = NULL; 632 633 debug_f("provider \"%s\", key %s, flags 0x%02x%s", 634 provider_path, sshkey_type(key), key->sk_flags, 635 (pin != NULL && *pin != '\0') ? " with-pin" : ""); 636 637 if (sigp != NULL) 638 *sigp = NULL; 639 if (lenp != NULL) 640 *lenp = 0; 641 type = sshkey_type_plain(key->type); 642 switch (type) { 643 #ifdef WITH_OPENSSL 644 case KEY_ECDSA_SK: 645 alg = SSH_SK_ECDSA; 646 break; 647 #endif /* WITH_OPENSSL */ 648 case KEY_ED25519_SK: 649 alg = SSH_SK_ED25519; 650 break; 651 default: 652 return SSH_ERR_INVALID_ARGUMENT; 653 } 654 if (provider_path == NULL || 655 key->sk_key_handle == NULL || 656 key->sk_application == NULL || *key->sk_application == '\0') { 657 r = SSH_ERR_INVALID_ARGUMENT; 658 goto out; 659 } 660 if ((skp = sshsk_open(provider_path)) == NULL) { 661 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 662 goto out; 663 } 664 #ifdef DEBUG_SK 665 fprintf(stderr, "%s: sk_flags = 0x%02x, sk_application = \"%s\"\n", 666 __func__, key->sk_flags, key->sk_application); 667 fprintf(stderr, "%s: sk_key_handle:\n", __func__); 668 sshbuf_dump(key->sk_key_handle, stderr); 669 #endif 670 if ((r = skp->sk_sign(alg, data, datalen, key->sk_application, 671 sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle), 672 key->sk_flags, pin, opts, &resp)) != 0) { 673 debug_f("sk_sign failed with code %d", r); 674 r = skerr_to_ssherr(r); 675 goto out; 676 } 677 /* Assemble signature */ 678 if ((sig = sshbuf_new()) == NULL) { 679 r = SSH_ERR_ALLOC_FAIL; 680 goto out; 681 } 682 if ((r = sshbuf_put_cstring(sig, sshkey_ssh_name_plain(key))) != 0) { 683 error_fr(r, "compose outer"); 684 goto out; 685 } 686 switch (type) { 687 #ifdef WITH_OPENSSL 688 case KEY_ECDSA_SK: 689 if ((r = sshsk_ecdsa_sig(resp, sig)) != 0) 690 goto out; 691 break; 692 #endif /* WITH_OPENSSL */ 693 case KEY_ED25519_SK: 694 if ((r = sshsk_ed25519_sig(resp, sig)) != 0) 695 goto out; 696 break; 697 } 698 #ifdef DEBUG_SK 699 fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n", 700 __func__, resp->flags, resp->counter); 701 fprintf(stderr, "%s: data to sign:\n", __func__); 702 sshbuf_dump_data(data, datalen, stderr); 703 fprintf(stderr, "%s: sigbuf:\n", __func__); 704 sshbuf_dump(sig, stderr); 705 #endif 706 if (sigp != NULL) { 707 if ((*sigp = malloc(sshbuf_len(sig))) == NULL) { 708 r = SSH_ERR_ALLOC_FAIL; 709 goto out; 710 } 711 memcpy(*sigp, sshbuf_ptr(sig), sshbuf_len(sig)); 712 } 713 if (lenp != NULL) 714 *lenp = sshbuf_len(sig); 715 /* success */ 716 r = 0; 717 out: 718 sshsk_free_options(opts); 719 sshsk_free(skp); 720 sshsk_free_sign_response(resp); 721 sshbuf_free(sig); 722 sshbuf_free(inner_sig); 723 return r; 724 } 725 726 static void 727 sshsk_free_sk_resident_keys(struct sk_resident_key **rks, size_t nrks) 728 { 729 size_t i; 730 731 if (nrks == 0 || rks == NULL) 732 return; 733 for (i = 0; i < nrks; i++) { 734 free(rks[i]->application); 735 freezero(rks[i]->user_id, rks[i]->user_id_len); 736 freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len); 737 freezero(rks[i]->key.public_key, rks[i]->key.public_key_len); 738 freezero(rks[i]->key.signature, rks[i]->key.signature_len); 739 freezero(rks[i]->key.attestation_cert, 740 rks[i]->key.attestation_cert_len); 741 freezero(rks[i], sizeof(**rks)); 742 } 743 free(rks); 744 } 745 746 static void 747 sshsk_free_resident_key(struct sshsk_resident_key *srk) 748 { 749 if (srk == NULL) 750 return; 751 sshkey_free(srk->key); 752 freezero(srk->user_id, srk->user_id_len); 753 free(srk); 754 } 755 756 757 void 758 sshsk_free_resident_keys(struct sshsk_resident_key **srks, size_t nsrks) 759 { 760 size_t i; 761 762 if (srks == NULL || nsrks == 0) 763 return; 764 765 for (i = 0; i < nsrks; i++) 766 sshsk_free_resident_key(srks[i]); 767 free(srks); 768 } 769 770 int 771 sshsk_load_resident(const char *provider_path, const char *device, 772 const char *pin, u_int flags, struct sshsk_resident_key ***srksp, 773 size_t *nsrksp) 774 { 775 struct sshsk_provider *skp = NULL; 776 int r = SSH_ERR_INTERNAL_ERROR; 777 struct sk_resident_key **rks = NULL; 778 size_t i, nrks = 0, nsrks = 0; 779 struct sshkey *key = NULL; 780 struct sshsk_resident_key *srk = NULL, **srks = NULL, **tmp; 781 uint8_t sk_flags; 782 struct sk_option **opts = NULL; 783 784 debug_f("provider \"%s\"%s", provider_path, 785 (pin != NULL && *pin != '\0') ? ", have-pin": ""); 786 787 if (srksp == NULL || nsrksp == NULL) 788 return SSH_ERR_INVALID_ARGUMENT; 789 *srksp = NULL; 790 *nsrksp = 0; 791 792 if ((r = make_options(device, NULL, &opts)) != 0) 793 goto out; 794 if ((skp = sshsk_open(provider_path)) == NULL) { 795 r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */ 796 goto out; 797 } 798 if ((r = skp->sk_load_resident_keys(pin, opts, &rks, &nrks)) != 0) { 799 error("Provider \"%s\" returned failure %d", provider_path, r); 800 r = skerr_to_ssherr(r); 801 goto out; 802 } 803 for (i = 0; i < nrks; i++) { 804 debug3_f("rk %zu: slot %zu, alg %d, app \"%s\", uidlen %zu", 805 i, rks[i]->slot, rks[i]->alg, rks[i]->application, 806 rks[i]->user_id_len); 807 /* XXX need better filter here */ 808 if (strncmp(rks[i]->application, "ssh:", 4) != 0) 809 continue; 810 switch (rks[i]->alg) { 811 case SSH_SK_ECDSA: 812 case SSH_SK_ED25519: 813 break; 814 default: 815 continue; 816 } 817 sk_flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY; 818 if ((rks[i]->flags & SSH_SK_USER_VERIFICATION_REQD)) 819 sk_flags |= SSH_SK_USER_VERIFICATION_REQD; 820 if ((r = sshsk_key_from_response(rks[i]->alg, 821 rks[i]->application, sk_flags, &rks[i]->key, &key)) != 0) 822 goto out; 823 if ((srk = calloc(1, sizeof(*srk))) == NULL) { 824 error_f("calloc failed"); 825 r = SSH_ERR_ALLOC_FAIL; 826 goto out; 827 } 828 srk->key = key; 829 key = NULL; /* transferred */ 830 if ((srk->user_id = calloc(1, rks[i]->user_id_len)) == NULL) { 831 error_f("calloc failed"); 832 r = SSH_ERR_ALLOC_FAIL; 833 goto out; 834 } 835 memcpy(srk->user_id, rks[i]->user_id, rks[i]->user_id_len); 836 srk->user_id_len = rks[i]->user_id_len; 837 if ((tmp = recallocarray(srks, nsrks, nsrks + 1, 838 sizeof(*tmp))) == NULL) { 839 error_f("recallocarray failed"); 840 r = SSH_ERR_ALLOC_FAIL; 841 goto out; 842 } 843 srks = tmp; 844 srks[nsrks++] = srk; 845 srk = NULL; 846 /* XXX synthesise comment */ 847 } 848 /* success */ 849 *srksp = srks; 850 *nsrksp = nsrks; 851 srks = NULL; 852 nsrks = 0; 853 r = 0; 854 out: 855 sshsk_free_options(opts); 856 sshsk_free(skp); 857 sshsk_free_sk_resident_keys(rks, nrks); 858 sshkey_free(key); 859 sshsk_free_resident_key(srk); 860 sshsk_free_resident_keys(srks, nsrks); 861 return r; 862 } 863 864
Indexes created Mon Mar 16 00:23:04 UTC 2026