1 /* $OpenBSD: auth-options.c,v 1.101 2023/07/14 07:44:21 dtucker Exp $ */ 2 /* 3 * Copyright (c) 2018 Damien Miller <djm@mindrot.org> 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 #include <sys/types.h> 19 #include <sys/queue.h> 20 21 #include <stdlib.h> 22 #include <netdb.h> 23 #include <pwd.h> 24 #include <string.h> 25 #include <stdio.h> 26 #include <stdint.h> 27 #include <stdarg.h> 28 #include <ctype.h> 29 #include <limits.h> 30 31 #include "xmalloc.h" 32 #include "ssherr.h" 33 #include "log.h" 34 #include "sshbuf.h" 35 #include "misc.h" 36 #include "sshkey.h" 37 #include "match.h" 38 #include "ssh2.h" 39 #include "auth-options.h" 40 41 static int 42 dup_strings(char ***dstp, size_t *ndstp, char **src, size_t nsrc) 43 { 44 char **dst; 45 size_t i, j; 46 47 *dstp = NULL; 48 *ndstp = 0; 49 50 if (nsrc == 0) 51 return 0; 52 if (nsrc >= SIZE_MAX / sizeof(*src) || 53 (dst = calloc(nsrc, sizeof(*src))) == NULL) 54 return -1; 55 for (i = 0; i < nsrc; i++) { 56 if ((dst[i] = strdup(src[i])) == NULL) { 57 for (j = 0; j < i; j++) 58 free(dst[j]); 59 free(dst); 60 return -1; 61 } 62 } 63 /* success */ 64 *dstp = dst; 65 *ndstp = nsrc; 66 return 0; 67 } 68 69 #define OPTIONS_CRITICAL 1 70 #define OPTIONS_EXTENSIONS 2 71 static int 72 cert_option_list(struct sshauthopt *opts, struct sshbuf *oblob, 73 u_int which, int crit) 74 { 75 char *command, *allowed; 76 char *name = NULL; 77 struct sshbuf *c = NULL, *data = NULL; 78 int r, ret = -1, found; 79 80 if ((c = sshbuf_fromb(oblob)) == NULL) { 81 error_f("sshbuf_fromb failed"); 82 goto out; 83 } 84 85 while (sshbuf_len(c) > 0) { 86 sshbuf_free(data); 87 data = NULL; 88 if ((r = sshbuf_get_cstring(c, &name, NULL)) != 0 || 89 (r = sshbuf_froms(c, &data)) != 0) { 90 error_r(r, "Unable to parse certificate options"); 91 goto out; 92 } 93 debug3("found certificate option \"%.100s\" len %zu", 94 name, sshbuf_len(data)); 95 found = 0; 96 if ((which & OPTIONS_EXTENSIONS) != 0) { 97 if (strcmp(name, "no-touch-required") == 0) { 98 opts->no_require_user_presence = 1; 99 found = 1; 100 } else if (strcmp(name, "permit-X11-forwarding") == 0) { 101 opts->permit_x11_forwarding_flag = 1; 102 found = 1; 103 } else if (strcmp(name, 104 "permit-agent-forwarding") == 0) { 105 opts->permit_agent_forwarding_flag = 1; 106 found = 1; 107 } else if (strcmp(name, 108 "permit-port-forwarding") == 0) { 109 opts->permit_port_forwarding_flag = 1; 110 found = 1; 111 } else if (strcmp(name, "permit-pty") == 0) { 112 opts->permit_pty_flag = 1; 113 found = 1; 114 } else if (strcmp(name, "permit-user-rc") == 0) { 115 opts->permit_user_rc = 1; 116 found = 1; 117 } 118 } 119 if (!found && (which & OPTIONS_CRITICAL) != 0) { 120 if (strcmp(name, "verify-required") == 0) { 121 opts->require_verify = 1; 122 found = 1; 123 } else if (strcmp(name, "force-command") == 0) { 124 if ((r = sshbuf_get_cstring(data, &command, 125 NULL)) != 0) { 126 error_r(r, "Unable to parse \"%s\" " 127 "section", name); 128 goto out; 129 } 130 if (opts->force_command != NULL) { 131 error("Certificate has multiple " 132 "force-command options"); 133 free(command); 134 goto out; 135 } 136 opts->force_command = command; 137 found = 1; 138 } else if (strcmp(name, "source-address") == 0) { 139 if ((r = sshbuf_get_cstring(data, &allowed, 140 NULL)) != 0) { 141 error_r(r, "Unable to parse \"%s\" " 142 "section", name); 143 goto out; 144 } 145 if (opts->required_from_host_cert != NULL) { 146 error("Certificate has multiple " 147 "source-address options"); 148 free(allowed); 149 goto out; 150 } 151 /* Check syntax */ 152 if (addr_match_cidr_list(NULL, allowed) == -1) { 153 error("Certificate source-address " 154 "contents invalid"); 155 goto out; 156 } 157 opts->required_from_host_cert = allowed; 158 found = 1; 159 } 160 } 161 162 if (!found) { 163 if (crit) { 164 error("Certificate critical option \"%s\" " 165 "is not supported", name); 166 goto out; 167 } else { 168 logit("Certificate extension \"%s\" " 169 "is not supported", name); 170 } 171 } else if (sshbuf_len(data) != 0) { 172 error("Certificate option \"%s\" corrupt " 173 "(extra data)", name); 174 goto out; 175 } 176 free(name); 177 name = NULL; 178 } 179 /* successfully parsed all options */ 180 ret = 0; 181 182 out: 183 free(name); 184 sshbuf_free(data); 185 sshbuf_free(c); 186 return ret; 187 } 188 189 struct sshauthopt * 190 sshauthopt_new(void) 191 { 192 struct sshauthopt *ret; 193 194 if ((ret = calloc(1, sizeof(*ret))) == NULL) 195 return NULL; 196 ret->force_tun_device = -1; 197 return ret; 198 } 199 200 void 201 sshauthopt_free(struct sshauthopt *opts) 202 { 203 size_t i; 204 205 if (opts == NULL) 206 return; 207 208 free(opts->cert_principals); 209 free(opts->force_command); 210 free(opts->required_from_host_cert); 211 free(opts->required_from_host_keys); 212 213 for (i = 0; i < opts->nenv; i++) 214 free(opts->env[i]); 215 free(opts->env); 216 217 for (i = 0; i < opts->npermitopen; i++) 218 free(opts->permitopen[i]); 219 free(opts->permitopen); 220 221 for (i = 0; i < opts->npermitlisten; i++) 222 free(opts->permitlisten[i]); 223 free(opts->permitlisten); 224 225 freezero(opts, sizeof(*opts)); 226 } 227 228 struct sshauthopt * 229 sshauthopt_new_with_keys_defaults(void) 230 { 231 struct sshauthopt *ret = NULL; 232 233 if ((ret = sshauthopt_new()) == NULL) 234 return NULL; 235 236 /* Defaults for authorized_keys flags */ 237 ret->permit_port_forwarding_flag = 1; 238 ret->permit_agent_forwarding_flag = 1; 239 ret->permit_x11_forwarding_flag = 1; 240 ret->permit_pty_flag = 1; 241 ret->permit_user_rc = 1; 242 return ret; 243 } 244 245 /* 246 * Parse and record a permitopen/permitlisten directive. 247 * Return 0 on success. Return -1 on failure and sets *errstrp to error reason. 248 */ 249 static int 250 handle_permit(const char **optsp, int allow_bare_port, 251 char ***permitsp, size_t *npermitsp, const char **errstrp) 252 { 253 char *opt, *tmp, *cp, *host, **permits = *permitsp; 254 size_t npermits = *npermitsp; 255 const char *errstr = "unknown error"; 256 257 if (npermits > SSH_AUTHOPT_PERMIT_MAX) { 258 *errstrp = "too many permission directives"; 259 return -1; 260 } 261 if ((opt = opt_dequote(optsp, &errstr)) == NULL) { 262 return -1; 263 } 264 if (allow_bare_port && strchr(opt, ':') == NULL) { 265 /* 266 * Allow a bare port number in permitlisten to indicate a 267 * listen_host wildcard. 268 */ 269 if (asprintf(&tmp, "*:%s", opt) == -1) { 270 free(opt); 271 *errstrp = "memory allocation failed"; 272 return -1; 273 } 274 free(opt); 275 opt = tmp; 276 } 277 if ((tmp = strdup(opt)) == NULL) { 278 free(opt); 279 *errstrp = "memory allocation failed"; 280 return -1; 281 } 282 cp = tmp; 283 /* validate syntax before recording it. */ 284 host = hpdelim2(&cp, NULL); 285 if (host == NULL || strlen(host) >= NI_MAXHOST) { 286 free(tmp); 287 free(opt); 288 *errstrp = "invalid permission hostname"; 289 return -1; 290 } 291 /* 292 * don't want to use permitopen_port to avoid 293 * dependency on channels.[ch] here. 294 */ 295 if (cp == NULL || 296 (strcmp(cp, "*") != 0 && a2port(cp) <= 0)) { 297 free(tmp); 298 free(opt); 299 *errstrp = "invalid permission port"; 300 return -1; 301 } 302 /* XXX - add streamlocal support */ 303 free(tmp); 304 /* Record it */ 305 if ((permits = recallocarray(permits, npermits, npermits + 1, 306 sizeof(*permits))) == NULL) { 307 free(opt); 308 /* NB. don't update *permitsp if alloc fails */ 309 *errstrp = "memory allocation failed"; 310 return -1; 311 } 312 permits[npermits++] = opt; 313 *permitsp = permits; 314 *npermitsp = npermits; 315 return 0; 316 } 317 318 struct sshauthopt * 319 sshauthopt_parse(const char *opts, const char **errstrp) 320 { 321 char **oarray, *opt, *cp, *tmp; 322 int r; 323 struct sshauthopt *ret = NULL; 324 const char *errstr = "unknown error"; 325 uint64_t valid_before; 326 size_t i, l; 327 328 if (errstrp != NULL) 329 *errstrp = NULL; 330 if ((ret = sshauthopt_new_with_keys_defaults()) == NULL) 331 goto alloc_fail; 332 333 if (opts == NULL) 334 return ret; 335 336 while (*opts && *opts != ' ' && *opts != '\t') { 337 /* flag options */ 338 if ((r = opt_flag("restrict", 0, &opts)) != -1) { 339 ret->restricted = 1; 340 ret->permit_port_forwarding_flag = 0; 341 ret->permit_agent_forwarding_flag = 0; 342 ret->permit_x11_forwarding_flag = 0; 343 ret->permit_pty_flag = 0; 344 ret->permit_user_rc = 0; 345 } else if ((r = opt_flag("cert-authority", 0, &opts)) != -1) { 346 ret->cert_authority = r; 347 } else if ((r = opt_flag("port-forwarding", 1, &opts)) != -1) { 348 ret->permit_port_forwarding_flag = r == 1; 349 } else if ((r = opt_flag("agent-forwarding", 1, &opts)) != -1) { 350 ret->permit_agent_forwarding_flag = r == 1; 351 } else if ((r = opt_flag("x11-forwarding", 1, &opts)) != -1) { 352 ret->permit_x11_forwarding_flag = r == 1; 353 } else if ((r = opt_flag("touch-required", 1, &opts)) != -1) { 354 ret->no_require_user_presence = r != 1; /* NB. flip */ 355 } else if ((r = opt_flag("verify-required", 1, &opts)) != -1) { 356 ret->require_verify = r == 1; 357 } else if ((r = opt_flag("pty", 1, &opts)) != -1) { 358 ret->permit_pty_flag = r == 1; 359 } else if ((r = opt_flag("user-rc", 1, &opts)) != -1) { 360 ret->permit_user_rc = r == 1; 361 } else if (opt_match(&opts, "command")) { 362 if (ret->force_command != NULL) { 363 errstr = "multiple \"command\" clauses"; 364 goto fail; 365 } 366 ret->force_command = opt_dequote(&opts, &errstr); 367 if (ret->force_command == NULL) 368 goto fail; 369 } else if (opt_match(&opts, "principals")) { 370 if (ret->cert_principals != NULL) { 371 errstr = "multiple \"principals\" clauses"; 372 goto fail; 373 } 374 ret->cert_principals = opt_dequote(&opts, &errstr); 375 if (ret->cert_principals == NULL) 376 goto fail; 377 } else if (opt_match(&opts, "from")) { 378 if (ret->required_from_host_keys != NULL) { 379 errstr = "multiple \"from\" clauses"; 380 goto fail; 381 } 382 ret->required_from_host_keys = opt_dequote(&opts, 383 &errstr); 384 if (ret->required_from_host_keys == NULL) 385 goto fail; 386 } else if (opt_match(&opts, "expiry-time")) { 387 if ((opt = opt_dequote(&opts, &errstr)) == NULL) 388 goto fail; 389 if (parse_absolute_time(opt, &valid_before) != 0 || 390 valid_before == 0) { 391 free(opt); 392 errstr = "invalid expires time"; 393 goto fail; 394 } 395 free(opt); 396 if (ret->valid_before == 0 || 397 valid_before < ret->valid_before) 398 ret->valid_before = valid_before; 399 } else if (opt_match(&opts, "environment")) { 400 if (ret->nenv > SSH_AUTHOPT_ENV_MAX) { 401 errstr = "too many environment strings"; 402 goto fail; 403 } 404 if ((opt = opt_dequote(&opts, &errstr)) == NULL) 405 goto fail; 406 /* env name must be alphanumeric and followed by '=' */ 407 if ((tmp = strchr(opt, '=')) == NULL) { 408 free(opt); 409 errstr = "invalid environment string"; 410 goto fail; 411 } 412 if ((cp = strdup(opt)) == NULL) { 413 free(opt); 414 goto alloc_fail; 415 } 416 l = (size_t)(tmp - opt); 417 cp[l] = '\0'; /* truncate at '=' */ 418 if (!valid_env_name(cp)) { 419 free(cp); 420 free(opt); 421 errstr = "invalid environment string"; 422 goto fail; 423 } 424 /* Check for duplicates; XXX O(n*log(n)) */ 425 for (i = 0; i < ret->nenv; i++) { 426 if (strncmp(ret->env[i], cp, l) == 0 && 427 ret->env[i][l] == '=') 428 break; 429 } 430 free(cp); 431 /* First match wins */ 432 if (i >= ret->nenv) { 433 /* Append it. */ 434 oarray = ret->env; 435 if ((ret->env = recallocarray(ret->env, 436 ret->nenv, ret->nenv + 1, 437 sizeof(*ret->env))) == NULL) { 438 free(opt); 439 /* put it back for cleanup */ 440 ret->env = oarray; 441 goto alloc_fail; 442 } 443 ret->env[ret->nenv++] = opt; 444 opt = NULL; /* transferred */ 445 } 446 free(opt); 447 } else if (opt_match(&opts, "permitopen")) { 448 if (handle_permit(&opts, 0, &ret->permitopen, 449 &ret->npermitopen, &errstr) != 0) 450 goto fail; 451 } else if (opt_match(&opts, "permitlisten")) { 452 if (handle_permit(&opts, 1, &ret->permitlisten, 453 &ret->npermitlisten, &errstr) != 0) 454 goto fail; 455 } else if (opt_match(&opts, "tunnel")) { 456 if ((opt = opt_dequote(&opts, &errstr)) == NULL) 457 goto fail; 458 ret->force_tun_device = a2tun(opt, NULL); 459 free(opt); 460 if (ret->force_tun_device == SSH_TUNID_ERR) { 461 errstr = "invalid tun device"; 462 goto fail; 463 } 464 } 465 /* 466 * Skip the comma, and move to the next option 467 * (or break out if there are no more). 468 */ 469 if (*opts == '\0' || *opts == ' ' || *opts == '\t') 470 break; /* End of options. */ 471 /* Anything other than a comma is an unknown option */ 472 if (*opts != ',') { 473 errstr = "unknown key option"; 474 goto fail; 475 } 476 opts++; 477 if (*opts == '\0') { 478 errstr = "unexpected end-of-options"; 479 goto fail; 480 } 481 } 482 483 /* success */ 484 if (errstrp != NULL) 485 *errstrp = NULL; 486 return ret; 487 488 alloc_fail: 489 errstr = "memory allocation failed"; 490 fail: 491 sshauthopt_free(ret); 492 if (errstrp != NULL) 493 *errstrp = errstr; 494 return NULL; 495 } 496 497 struct sshauthopt * 498 sshauthopt_from_cert(struct sshkey *k) 499 { 500 struct sshauthopt *ret; 501 502 if (k == NULL || !sshkey_type_is_cert(k->type) || k->cert == NULL || 503 k->cert->type != SSH2_CERT_TYPE_USER) 504 return NULL; 505 506 if ((ret = sshauthopt_new()) == NULL) 507 return NULL; 508 509 /* Handle options and critical extensions separately */ 510 if (cert_option_list(ret, k->cert->critical, 511 OPTIONS_CRITICAL, 1) == -1) { 512 sshauthopt_free(ret); 513 return NULL; 514 } 515 if (cert_option_list(ret, k->cert->extensions, 516 OPTIONS_EXTENSIONS, 0) == -1) { 517 sshauthopt_free(ret); 518 return NULL; 519 } 520 /* success */ 521 return ret; 522 } 523 524 /* 525 * Merges "additional" options to "primary" and returns the result. 526 * NB. Some options from primary have primacy. 527 */ 528 struct sshauthopt * 529 sshauthopt_merge(const struct sshauthopt *primary, 530 const struct sshauthopt *additional, const char **errstrp) 531 { 532 struct sshauthopt *ret; 533 const char *errstr = "internal error"; 534 const char *tmp; 535 536 if (errstrp != NULL) 537 *errstrp = NULL; 538 539 if ((ret = sshauthopt_new()) == NULL) 540 goto alloc_fail; 541 542 /* cert_authority and cert_principals are cleared in result */ 543 544 /* Prefer access lists from primary. */ 545 /* XXX err is both set and mismatch? */ 546 tmp = primary->required_from_host_cert; 547 if (tmp == NULL) 548 tmp = additional->required_from_host_cert; 549 if (tmp != NULL && (ret->required_from_host_cert = strdup(tmp)) == NULL) 550 goto alloc_fail; 551 tmp = primary->required_from_host_keys; 552 if (tmp == NULL) 553 tmp = additional->required_from_host_keys; 554 if (tmp != NULL && (ret->required_from_host_keys = strdup(tmp)) == NULL) 555 goto alloc_fail; 556 557 /* 558 * force_tun_device, permitopen/permitlisten and environment all 559 * prefer the primary. 560 */ 561 ret->force_tun_device = primary->force_tun_device; 562 if (ret->force_tun_device == -1) 563 ret->force_tun_device = additional->force_tun_device; 564 if (primary->nenv > 0) { 565 if (dup_strings(&ret->env, &ret->nenv, 566 primary->env, primary->nenv) != 0) 567 goto alloc_fail; 568 } else if (additional->nenv) { 569 if (dup_strings(&ret->env, &ret->nenv, 570 additional->env, additional->nenv) != 0) 571 goto alloc_fail; 572 } 573 if (primary->npermitopen > 0) { 574 if (dup_strings(&ret->permitopen, &ret->npermitopen, 575 primary->permitopen, primary->npermitopen) != 0) 576 goto alloc_fail; 577 } else if (additional->npermitopen > 0) { 578 if (dup_strings(&ret->permitopen, &ret->npermitopen, 579 additional->permitopen, additional->npermitopen) != 0) 580 goto alloc_fail; 581 } 582 583 if (primary->npermitlisten > 0) { 584 if (dup_strings(&ret->permitlisten, &ret->npermitlisten, 585 primary->permitlisten, primary->npermitlisten) != 0) 586 goto alloc_fail; 587 } else if (additional->npermitlisten > 0) { 588 if (dup_strings(&ret->permitlisten, &ret->npermitlisten, 589 additional->permitlisten, additional->npermitlisten) != 0) 590 goto alloc_fail; 591 } 592 593 #define OPTFLAG_AND(x) ret->x = (primary->x == 1) && (additional->x == 1) 594 #define OPTFLAG_OR(x) ret->x = (primary->x == 1) || (additional->x == 1) 595 /* Permissive flags are logical-AND (i.e. must be set in both) */ 596 OPTFLAG_AND(permit_port_forwarding_flag); 597 OPTFLAG_AND(permit_agent_forwarding_flag); 598 OPTFLAG_AND(permit_x11_forwarding_flag); 599 OPTFLAG_AND(permit_pty_flag); 600 OPTFLAG_AND(permit_user_rc); 601 OPTFLAG_AND(no_require_user_presence); 602 /* Restrictive flags are logical-OR (i.e. must be set in either) */ 603 OPTFLAG_OR(require_verify); 604 #undef OPTFLAG_AND 605 606 /* Earliest expiry time should win */ 607 if (primary->valid_before != 0) 608 ret->valid_before = primary->valid_before; 609 if (additional->valid_before != 0 && 610 additional->valid_before < ret->valid_before) 611 ret->valid_before = additional->valid_before; 612 613 /* 614 * When both multiple forced-command are specified, only 615 * proceed if they are identical, otherwise fail. 616 */ 617 if (primary->force_command != NULL && 618 additional->force_command != NULL) { 619 if (strcmp(primary->force_command, 620 additional->force_command) == 0) { 621 /* ok */ 622 ret->force_command = strdup(primary->force_command); 623 if (ret->force_command == NULL) 624 goto alloc_fail; 625 } else { 626 errstr = "forced command options do not match"; 627 goto fail; 628 } 629 } else if (primary->force_command != NULL) { 630 if ((ret->force_command = strdup( 631 primary->force_command)) == NULL) 632 goto alloc_fail; 633 } else if (additional->force_command != NULL) { 634 if ((ret->force_command = strdup( 635 additional->force_command)) == NULL) 636 goto alloc_fail; 637 } 638 /* success */ 639 if (errstrp != NULL) 640 *errstrp = NULL; 641 return ret; 642 643 alloc_fail: 644 errstr = "memory allocation failed"; 645 fail: 646 if (errstrp != NULL) 647 *errstrp = errstr; 648 sshauthopt_free(ret); 649 return NULL; 650 } 651 652 /* 653 * Copy options 654 */ 655 struct sshauthopt * 656 sshauthopt_copy(const struct sshauthopt *orig) 657 { 658 struct sshauthopt *ret; 659 660 if ((ret = sshauthopt_new()) == NULL) 661 return NULL; 662 663 #define OPTSCALAR(x) ret->x = orig->x 664 OPTSCALAR(permit_port_forwarding_flag); 665 OPTSCALAR(permit_agent_forwarding_flag); 666 OPTSCALAR(permit_x11_forwarding_flag); 667 OPTSCALAR(permit_pty_flag); 668 OPTSCALAR(permit_user_rc); 669 OPTSCALAR(restricted); 670 OPTSCALAR(cert_authority); 671 OPTSCALAR(force_tun_device); 672 OPTSCALAR(valid_before); 673 OPTSCALAR(no_require_user_presence); 674 OPTSCALAR(require_verify); 675 #undef OPTSCALAR 676 #define OPTSTRING(x) \ 677 do { \ 678 if (orig->x != NULL && (ret->x = strdup(orig->x)) == NULL) { \ 679 sshauthopt_free(ret); \ 680 return NULL; \ 681 } \ 682 } while (0) 683 OPTSTRING(cert_principals); 684 OPTSTRING(force_command); 685 OPTSTRING(required_from_host_cert); 686 OPTSTRING(required_from_host_keys); 687 #undef OPTSTRING 688 689 if (dup_strings(&ret->env, &ret->nenv, orig->env, orig->nenv) != 0 || 690 dup_strings(&ret->permitopen, &ret->npermitopen, 691 orig->permitopen, orig->npermitopen) != 0 || 692 dup_strings(&ret->permitlisten, &ret->npermitlisten, 693 orig->permitlisten, orig->npermitlisten) != 0) { 694 sshauthopt_free(ret); 695 return NULL; 696 } 697 return ret; 698 } 699 700 static int 701 serialise_array(struct sshbuf *m, char **a, size_t n) 702 { 703 struct sshbuf *b; 704 size_t i; 705 int r = SSH_ERR_INTERNAL_ERROR; 706 707 if (n > INT_MAX) 708 return SSH_ERR_INTERNAL_ERROR; 709 710 if ((b = sshbuf_new()) == NULL) { 711 return SSH_ERR_ALLOC_FAIL; 712 } 713 for (i = 0; i < n; i++) { 714 if ((r = sshbuf_put_cstring(b, a[i])) != 0) 715 goto out; 716 } 717 if ((r = sshbuf_put_u32(m, n)) != 0 || 718 (r = sshbuf_put_stringb(m, b)) != 0) 719 goto out; 720 /* success */ 721 r = 0; 722 out: 723 sshbuf_free(b); 724 return r; 725 } 726 727 static int 728 deserialise_array(struct sshbuf *m, char ***ap, size_t *np) 729 { 730 char **a = NULL; 731 size_t i, n = 0; 732 struct sshbuf *b = NULL; 733 u_int tmp; 734 int r = SSH_ERR_INTERNAL_ERROR; 735 736 if ((r = sshbuf_get_u32(m, &tmp)) != 0 || 737 (r = sshbuf_froms(m, &b)) != 0) 738 goto out; 739 if (tmp > INT_MAX) { 740 r = SSH_ERR_INVALID_FORMAT; 741 goto out; 742 } 743 n = tmp; 744 if (n > 0 && (a = calloc(n, sizeof(*a))) == NULL) { 745 r = SSH_ERR_ALLOC_FAIL; 746 goto out; 747 } 748 for (i = 0; i < n; i++) { 749 if ((r = sshbuf_get_cstring(b, &a[i], NULL)) != 0) 750 goto out; 751 } 752 /* success */ 753 r = 0; 754 *ap = a; 755 a = NULL; 756 *np = n; 757 n = 0; 758 out: 759 if (a != NULL) { 760 for (i = 0; i < n; i++) 761 free(a[i]); 762 free(a); 763 } 764 sshbuf_free(b); 765 return r; 766 } 767 768 static int 769 serialise_nullable_string(struct sshbuf *m, const char *s) 770 { 771 int r; 772 773 if ((r = sshbuf_put_u8(m, s == NULL)) != 0 || 774 (r = sshbuf_put_cstring(m, s)) != 0) 775 return r; 776 return 0; 777 } 778 779 static int 780 deserialise_nullable_string(struct sshbuf *m, char **sp) 781 { 782 int r; 783 u_char flag; 784 785 *sp = NULL; 786 if ((r = sshbuf_get_u8(m, &flag)) != 0 || 787 (r = sshbuf_get_cstring(m, flag ? NULL : sp, NULL)) != 0) 788 return r; 789 return 0; 790 } 791 792 int 793 sshauthopt_serialise(const struct sshauthopt *opts, struct sshbuf *m, 794 int untrusted) 795 { 796 int r = SSH_ERR_INTERNAL_ERROR; 797 798 /* Flag options */ 799 if ((r = sshbuf_put_u8(m, opts->permit_port_forwarding_flag)) != 0 || 800 (r = sshbuf_put_u8(m, opts->permit_agent_forwarding_flag)) != 0 || 801 (r = sshbuf_put_u8(m, opts->permit_x11_forwarding_flag)) != 0 || 802 (r = sshbuf_put_u8(m, opts->permit_pty_flag)) != 0 || 803 (r = sshbuf_put_u8(m, opts->permit_user_rc)) != 0 || 804 (r = sshbuf_put_u8(m, opts->restricted)) != 0 || 805 (r = sshbuf_put_u8(m, opts->cert_authority)) != 0 || 806 (r = sshbuf_put_u8(m, opts->no_require_user_presence)) != 0 || 807 (r = sshbuf_put_u8(m, opts->require_verify)) != 0) 808 return r; 809 810 /* Simple integer options */ 811 if ((r = sshbuf_put_u64(m, opts->valid_before)) != 0) 812 return r; 813 814 /* tunnel number can be negative to indicate "unset" */ 815 if ((r = sshbuf_put_u8(m, opts->force_tun_device == -1)) != 0 || 816 (r = sshbuf_put_u32(m, (opts->force_tun_device < 0) ? 817 0 : (u_int)opts->force_tun_device)) != 0) 818 return r; 819 820 /* String options; these may be NULL */ 821 if ((r = serialise_nullable_string(m, 822 untrusted ? "yes" : opts->cert_principals)) != 0 || 823 (r = serialise_nullable_string(m, 824 untrusted ? "true" : opts->force_command)) != 0 || 825 (r = serialise_nullable_string(m, 826 untrusted ? NULL : opts->required_from_host_cert)) != 0 || 827 (r = serialise_nullable_string(m, 828 untrusted ? NULL : opts->required_from_host_keys)) != 0) 829 return r; 830 831 /* Array options */ 832 if ((r = serialise_array(m, opts->env, 833 untrusted ? 0 : opts->nenv)) != 0 || 834 (r = serialise_array(m, opts->permitopen, 835 untrusted ? 0 : opts->npermitopen)) != 0 || 836 (r = serialise_array(m, opts->permitlisten, 837 untrusted ? 0 : opts->npermitlisten)) != 0) 838 return r; 839 840 /* success */ 841 return 0; 842 } 843 844 int 845 sshauthopt_deserialise(struct sshbuf *m, struct sshauthopt **optsp) 846 { 847 struct sshauthopt *opts = NULL; 848 int r = SSH_ERR_INTERNAL_ERROR; 849 u_char f; 850 u_int tmp; 851 852 if ((opts = calloc(1, sizeof(*opts))) == NULL) 853 return SSH_ERR_ALLOC_FAIL; 854 855 /* Flag options */ 856 #define OPT_FLAG(x) \ 857 do { \ 858 if ((r = sshbuf_get_u8(m, &f)) != 0) \ 859 goto out; \ 860 opts->x = f; \ 861 } while (0) 862 OPT_FLAG(permit_port_forwarding_flag); 863 OPT_FLAG(permit_agent_forwarding_flag); 864 OPT_FLAG(permit_x11_forwarding_flag); 865 OPT_FLAG(permit_pty_flag); 866 OPT_FLAG(permit_user_rc); 867 OPT_FLAG(restricted); 868 OPT_FLAG(cert_authority); 869 OPT_FLAG(no_require_user_presence); 870 OPT_FLAG(require_verify); 871 #undef OPT_FLAG 872 873 /* Simple integer options */ 874 if ((r = sshbuf_get_u64(m, &opts->valid_before)) != 0) 875 goto out; 876 877 /* tunnel number can be negative to indicate "unset" */ 878 if ((r = sshbuf_get_u8(m, &f)) != 0 || 879 (r = sshbuf_get_u32(m, &tmp)) != 0) 880 goto out; 881 opts->force_tun_device = f ? -1 : (int)tmp; 882 883 /* String options may be NULL */ 884 if ((r = deserialise_nullable_string(m, &opts->cert_principals)) != 0 || 885 (r = deserialise_nullable_string(m, &opts->force_command)) != 0 || 886 (r = deserialise_nullable_string(m, 887 &opts->required_from_host_cert)) != 0 || 888 (r = deserialise_nullable_string(m, 889 &opts->required_from_host_keys)) != 0) 890 goto out; 891 892 /* Array options */ 893 if ((r = deserialise_array(m, &opts->env, &opts->nenv)) != 0 || 894 (r = deserialise_array(m, 895 &opts->permitopen, &opts->npermitopen)) != 0 || 896 (r = deserialise_array(m, 897 &opts->permitlisten, &opts->npermitlisten)) != 0) 898 goto out; 899 900 /* success */ 901 r = 0; 902 *optsp = opts; 903 opts = NULL; 904 out: 905 sshauthopt_free(opts); 906 return r; 907 } 908