1 /* $OpenBSD: auth-options.c,v 1.79 2018/04/06 04:15:45 djm 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 <netdb.h> 22 #include <pwd.h> 23 #include <string.h> 24 #include <stdio.h> 25 #include <stdarg.h> 26 #include <ctype.h> 27 #include <limits.h> 28 29 #include "xmalloc.h" 30 #include "ssherr.h" 31 #include "log.h" 32 #include "sshbuf.h" 33 #include "misc.h" 34 #include "sshkey.h" 35 #include "match.h" 36 #include "ssh2.h" 37 #include "auth-options.h" 38 39 /* 40 * Match flag 'opt' in *optsp, and if allow_negate is set then also match 41 * 'no-opt'. Returns -1 if option not matched, 1 if option matches or 0 42 * if negated option matches. 43 * If the option or negated option matches, then *optsp is updated to 44 * point to the first character after the option. 45 */ 46 static int 47 opt_flag(const char *opt, int allow_negate, const char **optsp) 48 { 49 size_t opt_len = strlen(opt); 50 const char *opts = *optsp; 51 int negate = 0; 52 53 if (allow_negate && strncasecmp(opts, "no-", 3) == 0) { 54 opts += 3; 55 negate = 1; 56 } 57 if (strncasecmp(opts, opt, opt_len) == 0) { 58 *optsp = opts + opt_len; 59 return negate ? 0 : 1; 60 } 61 return -1; 62 } 63 64 static char * 65 opt_dequote(const char **sp, const char **errstrp) 66 { 67 const char *s = *sp; 68 char *ret; 69 size_t i; 70 71 *errstrp = NULL; 72 if (*s != '"') { 73 *errstrp = "missing start quote"; 74 return NULL; 75 } 76 s++; 77 if ((ret = malloc(strlen((s)) + 1)) == NULL) { 78 *errstrp = "memory allocation failed"; 79 return NULL; 80 } 81 for (i = 0; *s != '\0' && *s != '"';) { 82 if (s[0] == '\\' && s[1] == '"') 83 s++; 84 ret[i++] = *s++; 85 } 86 if (*s == '\0') { 87 *errstrp = "missing end quote"; 88 free(ret); 89 return NULL; 90 } 91 ret[i] = '\0'; 92 s++; 93 *sp = s; 94 return ret; 95 } 96 97 static int 98 opt_match(const char **opts, const char *term) 99 { 100 if (strncasecmp((*opts), term, strlen(term)) == 0 && 101 (*opts)[strlen(term)] == '=') { 102 *opts += strlen(term) + 1; 103 return 1; 104 } 105 return 0; 106 } 107 108 static int 109 dup_strings(char ***dstp, size_t *ndstp, char **src, size_t nsrc) 110 { 111 char **dst; 112 size_t i, j; 113 114 *dstp = NULL; 115 *ndstp = 0; 116 if (nsrc == 0) 117 return 0; 118 119 if ((dst = calloc(nsrc, sizeof(*src))) == NULL) 120 return -1; 121 for (i = 0; i < nsrc; i++) { 122 if ((dst[i] = strdup(src[i])) == NULL) { 123 for (j = 0; j < i; j++) 124 free(dst[j]); 125 free(dst); 126 return -1; 127 } 128 } 129 /* success */ 130 *dstp = dst; 131 *ndstp = nsrc; 132 return 0; 133 } 134 135 #define OPTIONS_CRITICAL 1 136 #define OPTIONS_EXTENSIONS 2 137 static int 138 cert_option_list(struct sshauthopt *opts, struct sshbuf *oblob, 139 u_int which, int crit) 140 { 141 char *command, *allowed; 142 char *name = NULL; 143 struct sshbuf *c = NULL, *data = NULL; 144 int r, ret = -1, found; 145 146 if ((c = sshbuf_fromb(oblob)) == NULL) { 147 error("%s: sshbuf_fromb failed", __func__); 148 goto out; 149 } 150 151 while (sshbuf_len(c) > 0) { 152 sshbuf_free(data); 153 data = NULL; 154 if ((r = sshbuf_get_cstring(c, &name, NULL)) != 0 || 155 (r = sshbuf_froms(c, &data)) != 0) { 156 error("Unable to parse certificate options: %s", 157 ssh_err(r)); 158 goto out; 159 } 160 debug3("found certificate option \"%.100s\" len %zu", 161 name, sshbuf_len(data)); 162 found = 0; 163 if ((which & OPTIONS_EXTENSIONS) != 0) { 164 if (strcmp(name, "permit-X11-forwarding") == 0) { 165 opts->permit_x11_forwarding_flag = 1; 166 found = 1; 167 } else if (strcmp(name, 168 "permit-agent-forwarding") == 0) { 169 opts->permit_agent_forwarding_flag = 1; 170 found = 1; 171 } else if (strcmp(name, 172 "permit-port-forwarding") == 0) { 173 opts->permit_port_forwarding_flag = 1; 174 found = 1; 175 } else if (strcmp(name, "permit-pty") == 0) { 176 opts->permit_pty_flag = 1; 177 found = 1; 178 } else if (strcmp(name, "permit-user-rc") == 0) { 179 opts->permit_user_rc = 1; 180 found = 1; 181 } 182 } 183 if (!found && (which & OPTIONS_CRITICAL) != 0) { 184 if (strcmp(name, "force-command") == 0) { 185 if ((r = sshbuf_get_cstring(data, &command, 186 NULL)) != 0) { 187 error("Unable to parse \"%s\" " 188 "section: %s", name, ssh_err(r)); 189 goto out; 190 } 191 if (opts->force_command != NULL) { 192 error("Certificate has multiple " 193 "force-command options"); 194 free(command); 195 goto out; 196 } 197 opts->force_command = command; 198 found = 1; 199 } 200 if (strcmp(name, "source-address") == 0) { 201 if ((r = sshbuf_get_cstring(data, &allowed, 202 NULL)) != 0) { 203 error("Unable to parse \"%s\" " 204 "section: %s", name, ssh_err(r)); 205 goto out; 206 } 207 if (opts->required_from_host_cert != NULL) { 208 error("Certificate has multiple " 209 "source-address options"); 210 free(allowed); 211 goto out; 212 } 213 /* Check syntax */ 214 if (addr_match_cidr_list(NULL, allowed) == -1) { 215 error("Certificate source-address " 216 "contents invalid"); 217 goto out; 218 } 219 opts->required_from_host_cert = allowed; 220 found = 1; 221 } 222 } 223 224 if (!found) { 225 if (crit) { 226 error("Certificate critical option \"%s\" " 227 "is not supported", name); 228 goto out; 229 } else { 230 logit("Certificate extension \"%s\" " 231 "is not supported", name); 232 } 233 } else if (sshbuf_len(data) != 0) { 234 error("Certificate option \"%s\" corrupt " 235 "(extra data)", name); 236 goto out; 237 } 238 free(name); 239 name = NULL; 240 } 241 /* successfully parsed all options */ 242 ret = 0; 243 244 out: 245 free(name); 246 sshbuf_free(data); 247 sshbuf_free(c); 248 return ret; 249 } 250 251 struct sshauthopt * 252 sshauthopt_new(void) 253 { 254 struct sshauthopt *ret; 255 256 if ((ret = calloc(1, sizeof(*ret))) == NULL) 257 return NULL; 258 ret->force_tun_device = -1; 259 return ret; 260 } 261 262 void 263 sshauthopt_free(struct sshauthopt *opts) 264 { 265 size_t i; 266 267 if (opts == NULL) 268 return; 269 270 free(opts->cert_principals); 271 free(opts->force_command); 272 free(opts->required_from_host_cert); 273 free(opts->required_from_host_keys); 274 275 for (i = 0; i < opts->nenv; i++) 276 free(opts->env[i]); 277 free(opts->env); 278 279 for (i = 0; i < opts->npermitopen; i++) 280 free(opts->permitopen[i]); 281 free(opts->permitopen); 282 283 explicit_bzero(opts, sizeof(*opts)); 284 free(opts); 285 } 286 287 struct sshauthopt * 288 sshauthopt_new_with_keys_defaults(void) 289 { 290 struct sshauthopt *ret = NULL; 291 292 if ((ret = sshauthopt_new()) == NULL) 293 return NULL; 294 295 /* Defaults for authorized_keys flags */ 296 ret->permit_port_forwarding_flag = 1; 297 ret->permit_agent_forwarding_flag = 1; 298 ret->permit_x11_forwarding_flag = 1; 299 ret->permit_pty_flag = 1; 300 ret->permit_user_rc = 1; 301 return ret; 302 } 303 304 struct sshauthopt * 305 sshauthopt_parse(const char *opts, const char **errstrp) 306 { 307 char **oarray, *opt, *cp, *tmp, *host; 308 int r; 309 struct sshauthopt *ret = NULL; 310 const char *errstr = "unknown error"; 311 uint64_t valid_before; 312 313 if (errstrp != NULL) 314 *errstrp = NULL; 315 if ((ret = sshauthopt_new_with_keys_defaults()) == NULL) 316 goto alloc_fail; 317 318 if (opts == NULL) 319 return ret; 320 321 while (*opts && *opts != ' ' && *opts != '\t') { 322 /* flag options */ 323 if ((r = opt_flag("restrict", 0, &opts)) != -1) { 324 ret->restricted = 1; 325 ret->permit_port_forwarding_flag = 0; 326 ret->permit_agent_forwarding_flag = 0; 327 ret->permit_x11_forwarding_flag = 0; 328 ret->permit_pty_flag = 0; 329 ret->permit_user_rc = 0; 330 } else if ((r = opt_flag("cert-authority", 0, &opts)) != -1) { 331 ret->cert_authority = r; 332 } else if ((r = opt_flag("port-forwarding", 1, &opts)) != -1) { 333 ret->permit_port_forwarding_flag = r == 1; 334 } else if ((r = opt_flag("agent-forwarding", 1, &opts)) != -1) { 335 ret->permit_agent_forwarding_flag = r == 1; 336 } else if ((r = opt_flag("x11-forwarding", 1, &opts)) != -1) { 337 ret->permit_x11_forwarding_flag = r == 1; 338 } else if ((r = opt_flag("pty", 1, &opts)) != -1) { 339 ret->permit_pty_flag = r == 1; 340 } else if ((r = opt_flag("user-rc", 1, &opts)) != -1) { 341 ret->permit_user_rc = r == 1; 342 } else if (opt_match(&opts, "command")) { 343 if (ret->force_command != NULL) { 344 errstr = "multiple \"command\" clauses"; 345 goto fail; 346 } 347 ret->force_command = opt_dequote(&opts, &errstr); 348 if (ret->force_command == NULL) 349 goto fail; 350 } else if (opt_match(&opts, "principals")) { 351 if (ret->cert_principals != NULL) { 352 errstr = "multiple \"principals\" clauses"; 353 goto fail; 354 } 355 ret->cert_principals = opt_dequote(&opts, &errstr); 356 if (ret->cert_principals == NULL) 357 goto fail; 358 } else if (opt_match(&opts, "from")) { 359 if (ret->required_from_host_keys != NULL) { 360 errstr = "multiple \"from\" clauses"; 361 goto fail; 362 } 363 ret->required_from_host_keys = opt_dequote(&opts, 364 &errstr); 365 if (ret->required_from_host_keys == NULL) 366 goto fail; 367 } else if (opt_match(&opts, "expiry-time")) { 368 if ((opt = opt_dequote(&opts, &errstr)) == NULL) 369 goto fail; 370 if (parse_absolute_time(opt, &valid_before) != 0 || 371 valid_before == 0) { 372 free(opt); 373 errstr = "invalid expires time"; 374 goto fail; 375 } 376 free(opt); 377 if (ret->valid_before == 0 || 378 valid_before < ret->valid_before) 379 ret->valid_before = valid_before; 380 } else if (opt_match(&opts, "environment")) { 381 if (ret->nenv > INT_MAX) { 382 errstr = "too many environment strings"; 383 goto fail; 384 } 385 if ((opt = opt_dequote(&opts, &errstr)) == NULL) 386 goto fail; 387 /* env name must be alphanumeric and followed by '=' */ 388 if ((tmp = strchr(opt, '=')) == NULL) { 389 free(opt); 390 errstr = "invalid environment string"; 391 goto fail; 392 } 393 for (cp = opt; cp < tmp; cp++) { 394 if (!isalnum((u_char)*cp) && *cp != '_') { 395 free(opt); 396 errstr = "invalid environment string"; 397 goto fail; 398 } 399 } 400 /* Append it. */ 401 oarray = ret->env; 402 if ((ret->env = recallocarray(ret->env, ret->nenv, 403 ret->nenv + 1, sizeof(*ret->env))) == NULL) { 404 free(opt); 405 ret->env = oarray; /* put it back for cleanup */ 406 goto alloc_fail; 407 } 408 ret->env[ret->nenv++] = opt; 409 } else if (opt_match(&opts, "permitopen")) { 410 if (ret->npermitopen > INT_MAX) { 411 errstr = "too many permitopens"; 412 goto fail; 413 } 414 if ((opt = opt_dequote(&opts, &errstr)) == NULL) 415 goto fail; 416 if ((tmp = strdup(opt)) == NULL) { 417 free(opt); 418 goto alloc_fail; 419 } 420 cp = tmp; 421 /* validate syntax of permitopen before recording it. */ 422 host = hpdelim(&cp); 423 if (host == NULL || strlen(host) >= NI_MAXHOST) { 424 free(tmp); 425 free(opt); 426 errstr = "invalid permitopen hostname"; 427 goto fail; 428 } 429 /* 430 * don't want to use permitopen_port to avoid 431 * dependency on channels.[ch] here. 432 */ 433 if (cp == NULL || 434 (strcmp(cp, "*") != 0 && a2port(cp) <= 0)) { 435 free(tmp); 436 free(opt); 437 errstr = "invalid permitopen port"; 438 goto fail; 439 } 440 /* XXX - add streamlocal support */ 441 free(tmp); 442 /* Record it */ 443 oarray = ret->permitopen; 444 if ((ret->permitopen = recallocarray(ret->permitopen, 445 ret->npermitopen, ret->npermitopen + 1, 446 sizeof(*ret->permitopen))) == NULL) { 447 free(opt); 448 ret->permitopen = oarray; 449 goto alloc_fail; 450 } 451 ret->permitopen[ret->npermitopen++] = opt; 452 } else if (opt_match(&opts, "tunnel")) { 453 if ((opt = opt_dequote(&opts, &errstr)) == NULL) 454 goto fail; 455 ret->force_tun_device = a2tun(opt, NULL); 456 free(opt); 457 if (ret->force_tun_device == SSH_TUNID_ERR) { 458 errstr = "invalid tun device"; 459 goto fail; 460 } 461 } 462 /* 463 * Skip the comma, and move to the next option 464 * (or break out if there are no more). 465 */ 466 if (*opts == '\0' || *opts == ' ' || *opts == '\t') 467 break; /* End of options. */ 468 /* Anything other than a comma is an unknown option */ 469 if (*opts != ',') { 470 errstr = "unknown key option"; 471 goto fail; 472 } 473 opts++; 474 if (*opts == '\0') { 475 errstr = "unexpected end-of-options"; 476 goto fail; 477 } 478 } 479 480 /* success */ 481 if (errstrp != NULL) 482 *errstrp = NULL; 483 return ret; 484 485 alloc_fail: 486 errstr = "memory allocation failed"; 487 fail: 488 sshauthopt_free(ret); 489 if (errstrp != NULL) 490 *errstrp = errstr; 491 return NULL; 492 } 493 494 struct sshauthopt * 495 sshauthopt_from_cert(struct sshkey *k) 496 { 497 struct sshauthopt *ret; 498 499 if (k == NULL || !sshkey_type_is_cert(k->type) || k->cert == NULL || 500 k->cert->type != SSH2_CERT_TYPE_USER) 501 return NULL; 502 503 if ((ret = sshauthopt_new()) == NULL) 504 return NULL; 505 506 /* Handle options and critical extensions separately */ 507 if (cert_option_list(ret, k->cert->critical, 508 OPTIONS_CRITICAL, 1) == -1) { 509 sshauthopt_free(ret); 510 return NULL; 511 } 512 if (cert_option_list(ret, k->cert->extensions, 513 OPTIONS_EXTENSIONS, 0) == -1) { 514 sshauthopt_free(ret); 515 return NULL; 516 } 517 /* success */ 518 return ret; 519 } 520 521 /* 522 * Merges "additional" options to "primary" and returns the result. 523 * NB. Some options from primary have primacy. 524 */ 525 struct sshauthopt * 526 sshauthopt_merge(const struct sshauthopt *primary, 527 const struct sshauthopt *additional, const char **errstrp) 528 { 529 struct sshauthopt *ret; 530 const char *errstr = "internal error"; 531 const char *tmp; 532 533 if (errstrp != NULL) 534 *errstrp = NULL; 535 536 if ((ret = sshauthopt_new()) == NULL) 537 goto alloc_fail; 538 539 /* cert_authority and cert_principals are cleared in result */ 540 541 /* Prefer access lists from primary. */ 542 /* XXX err is both set and mismatch? */ 543 tmp = primary->required_from_host_cert; 544 if (tmp == NULL) 545 tmp = additional->required_from_host_cert; 546 if (tmp != NULL && (ret->required_from_host_cert = strdup(tmp)) == NULL) 547 goto alloc_fail; 548 tmp = primary->required_from_host_keys; 549 if (tmp == NULL) 550 tmp = additional->required_from_host_keys; 551 if (tmp != NULL && (ret->required_from_host_keys = strdup(tmp)) == NULL) 552 goto alloc_fail; 553 554 /* force_tun_device, permitopen and environment prefer the primary. */ 555 ret->force_tun_device = primary->force_tun_device; 556 if (ret->force_tun_device == -1) 557 ret->force_tun_device = additional->force_tun_device; 558 if (primary->nenv > 0) { 559 if (dup_strings(&ret->env, &ret->nenv, 560 primary->env, primary->nenv) != 0) 561 goto alloc_fail; 562 } else if (additional->nenv) { 563 if (dup_strings(&ret->env, &ret->nenv, 564 additional->env, additional->nenv) != 0) 565 goto alloc_fail; 566 } 567 if (primary->npermitopen > 0) { 568 if (dup_strings(&ret->permitopen, &ret->npermitopen, 569 primary->permitopen, primary->npermitopen) != 0) 570 goto alloc_fail; 571 } else if (additional->npermitopen > 0) { 572 if (dup_strings(&ret->permitopen, &ret->npermitopen, 573 additional->permitopen, additional->npermitopen) != 0) 574 goto alloc_fail; 575 } 576 577 /* Flags are logical-AND (i.e. must be set in both for permission) */ 578 #define OPTFLAG(x) ret->x = (primary->x == 1) && (additional->x == 1) 579 OPTFLAG(permit_port_forwarding_flag); 580 OPTFLAG(permit_agent_forwarding_flag); 581 OPTFLAG(permit_x11_forwarding_flag); 582 OPTFLAG(permit_pty_flag); 583 OPTFLAG(permit_user_rc); 584 #undef OPTFLAG 585 586 /* Earliest expiry time should win */ 587 if (primary->valid_before != 0) 588 ret->valid_before = primary->valid_before; 589 if (additional->valid_before != 0 && 590 additional->valid_before < ret->valid_before) 591 ret->valid_before = additional->valid_before; 592 593 /* 594 * When both multiple forced-command are specified, only 595 * proceed if they are identical, otherwise fail. 596 */ 597 if (primary->force_command != NULL && 598 additional->force_command != NULL) { 599 if (strcmp(primary->force_command, 600 additional->force_command) == 0) { 601 /* ok */ 602 ret->force_command = strdup(primary->force_command); 603 if (ret->force_command == NULL) 604 goto alloc_fail; 605 } else { 606 errstr = "forced command options do not match"; 607 goto fail; 608 } 609 } else if (primary->force_command != NULL) { 610 if ((ret->force_command = strdup( 611 primary->force_command)) == NULL) 612 goto alloc_fail; 613 } else if (additional->force_command != NULL) { 614 if ((ret->force_command = strdup( 615 additional->force_command)) == NULL) 616 goto alloc_fail; 617 } 618 /* success */ 619 if (errstrp != NULL) 620 *errstrp = NULL; 621 return ret; 622 623 alloc_fail: 624 errstr = "memory allocation failed"; 625 fail: 626 if (errstrp != NULL) 627 *errstrp = errstr; 628 sshauthopt_free(ret); 629 return NULL; 630 } 631 632 /* 633 * Copy options 634 */ 635 struct sshauthopt * 636 sshauthopt_copy(const struct sshauthopt *orig) 637 { 638 struct sshauthopt *ret; 639 640 if ((ret = sshauthopt_new()) == NULL) 641 return NULL; 642 643 #define OPTSCALAR(x) ret->x = orig->x 644 OPTSCALAR(permit_port_forwarding_flag); 645 OPTSCALAR(permit_agent_forwarding_flag); 646 OPTSCALAR(permit_x11_forwarding_flag); 647 OPTSCALAR(permit_pty_flag); 648 OPTSCALAR(permit_user_rc); 649 OPTSCALAR(restricted); 650 OPTSCALAR(cert_authority); 651 OPTSCALAR(force_tun_device); 652 OPTSCALAR(valid_before); 653 #undef OPTSCALAR 654 #define OPTSTRING(x) \ 655 do { \ 656 if (orig->x != NULL && (ret->x = strdup(orig->x)) == NULL) { \ 657 sshauthopt_free(ret); \ 658 return NULL; \ 659 } \ 660 } while (0) 661 OPTSTRING(cert_principals); 662 OPTSTRING(force_command); 663 OPTSTRING(required_from_host_cert); 664 OPTSTRING(required_from_host_keys); 665 #undef OPTSTRING 666 667 if (dup_strings(&ret->env, &ret->nenv, orig->env, orig->nenv) != 0 || 668 dup_strings(&ret->permitopen, &ret->npermitopen, 669 orig->permitopen, orig->npermitopen) != 0) { 670 sshauthopt_free(ret); 671 return NULL; 672 } 673 return ret; 674 } 675 676 static int 677 serialise_array(struct sshbuf *m, char **a, size_t n) 678 { 679 struct sshbuf *b; 680 size_t i; 681 int r; 682 683 if (n > INT_MAX) 684 return SSH_ERR_INTERNAL_ERROR; 685 686 if ((b = sshbuf_new()) == NULL) { 687 return SSH_ERR_ALLOC_FAIL; 688 } 689 for (i = 0; i < n; i++) { 690 if ((r = sshbuf_put_cstring(b, a[i])) != 0) { 691 sshbuf_free(b); 692 return r; 693 } 694 } 695 if ((r = sshbuf_put_u32(m, n)) != 0 || 696 (r = sshbuf_put_stringb(m, b)) != 0) { 697 sshbuf_free(b); 698 return r; 699 } 700 /* success */ 701 return 0; 702 } 703 704 static int 705 deserialise_array(struct sshbuf *m, char ***ap, size_t *np) 706 { 707 char **a = NULL; 708 size_t i, n = 0; 709 struct sshbuf *b = NULL; 710 u_int tmp; 711 int r = SSH_ERR_INTERNAL_ERROR; 712 713 if ((r = sshbuf_get_u32(m, &tmp)) != 0 || 714 (r = sshbuf_froms(m, &b)) != 0) 715 goto out; 716 if (tmp > INT_MAX) { 717 r = SSH_ERR_INVALID_FORMAT; 718 goto out; 719 } 720 n = tmp; 721 if (n > 0 && (a = calloc(n, sizeof(*a))) == NULL) { 722 r = SSH_ERR_ALLOC_FAIL; 723 goto out; 724 } 725 for (i = 0; i < n; i++) { 726 if ((r = sshbuf_get_cstring(b, &a[i], NULL)) != 0) 727 goto out; 728 } 729 /* success */ 730 r = 0; 731 *ap = a; 732 a = NULL; 733 *np = n; 734 n = 0; 735 out: 736 for (i = 0; i < n; i++) 737 free(a[i]); 738 free(a); 739 sshbuf_free(b); 740 return r; 741 } 742 743 static int 744 serialise_nullable_string(struct sshbuf *m, const char *s) 745 { 746 int r; 747 748 if ((r = sshbuf_put_u8(m, s == NULL)) != 0 || 749 (r = sshbuf_put_cstring(m, s)) != 0) 750 return r; 751 return 0; 752 } 753 754 static int 755 deserialise_nullable_string(struct sshbuf *m, char **sp) 756 { 757 int r; 758 u_char flag; 759 760 *sp = NULL; 761 if ((r = sshbuf_get_u8(m, &flag)) != 0 || 762 (r = sshbuf_get_cstring(m, flag ? NULL : sp, NULL)) != 0) 763 return r; 764 return 0; 765 } 766 767 int 768 sshauthopt_serialise(const struct sshauthopt *opts, struct sshbuf *m, 769 int untrusted) 770 { 771 int r = SSH_ERR_INTERNAL_ERROR; 772 773 /* Flag and simple integer options */ 774 if ((r = sshbuf_put_u8(m, opts->permit_port_forwarding_flag)) != 0 || 775 (r = sshbuf_put_u8(m, opts->permit_agent_forwarding_flag)) != 0 || 776 (r = sshbuf_put_u8(m, opts->permit_x11_forwarding_flag)) != 0 || 777 (r = sshbuf_put_u8(m, opts->permit_pty_flag)) != 0 || 778 (r = sshbuf_put_u8(m, opts->permit_user_rc)) != 0 || 779 (r = sshbuf_put_u8(m, opts->restricted)) != 0 || 780 (r = sshbuf_put_u8(m, opts->cert_authority)) != 0 || 781 (r = sshbuf_put_u64(m, opts->valid_before)) != 0) 782 return r; 783 784 /* tunnel number can be negative to indicate "unset" */ 785 if ((r = sshbuf_put_u8(m, opts->force_tun_device == -1)) != 0 || 786 (r = sshbuf_put_u32(m, (opts->force_tun_device < 0) ? 787 0 : (u_int)opts->force_tun_device)) != 0) 788 return r; 789 790 /* String options; these may be NULL */ 791 if ((r = serialise_nullable_string(m, 792 untrusted ? "yes" : opts->cert_principals)) != 0 || 793 (r = serialise_nullable_string(m, 794 untrusted ? "true" : opts->force_command)) != 0 || 795 (r = serialise_nullable_string(m, 796 untrusted ? NULL : opts->required_from_host_cert)) != 0 || 797 (r = serialise_nullable_string(m, 798 untrusted ? NULL : opts->required_from_host_keys)) != 0) 799 return r; 800 801 /* Array options */ 802 if ((r = serialise_array(m, opts->env, 803 untrusted ? 0 : opts->nenv)) != 0 || 804 (r = serialise_array(m, opts->permitopen, 805 untrusted ? 0 : opts->npermitopen)) != 0) 806 return r; 807 808 /* success */ 809 return 0; 810 } 811 812 int 813 sshauthopt_deserialise(struct sshbuf *m, struct sshauthopt **optsp) 814 { 815 struct sshauthopt *opts = NULL; 816 int r = SSH_ERR_INTERNAL_ERROR; 817 u_char f; 818 u_int tmp; 819 820 if ((opts = calloc(1, sizeof(*opts))) == NULL) 821 return SSH_ERR_ALLOC_FAIL; 822 823 #define OPT_FLAG(x) \ 824 do { \ 825 if ((r = sshbuf_get_u8(m, &f)) != 0) \ 826 goto out; \ 827 opts->x = f; \ 828 } while (0) 829 OPT_FLAG(permit_port_forwarding_flag); 830 OPT_FLAG(permit_agent_forwarding_flag); 831 OPT_FLAG(permit_x11_forwarding_flag); 832 OPT_FLAG(permit_pty_flag); 833 OPT_FLAG(permit_user_rc); 834 OPT_FLAG(restricted); 835 OPT_FLAG(cert_authority); 836 #undef OPT_FLAG 837 838 if ((r = sshbuf_get_u64(m, &opts->valid_before)) != 0) 839 goto out; 840 841 /* tunnel number can be negative to indicate "unset" */ 842 if ((r = sshbuf_get_u8(m, &f)) != 0 || 843 (r = sshbuf_get_u32(m, &tmp)) != 0) 844 goto out; 845 opts->force_tun_device = f ? -1 : (int)tmp; 846 847 /* String options may be NULL */ 848 if ((r = deserialise_nullable_string(m, &opts->cert_principals)) != 0 || 849 (r = deserialise_nullable_string(m, &opts->force_command)) != 0 || 850 (r = deserialise_nullable_string(m, 851 &opts->required_from_host_cert)) != 0 || 852 (r = deserialise_nullable_string(m, 853 &opts->required_from_host_keys)) != 0) 854 goto out; 855 856 /* Array options */ 857 if ((r = deserialise_array(m, &opts->env, &opts->nenv)) != 0 || 858 (r = deserialise_array(m, 859 &opts->permitopen, &opts->npermitopen)) != 0) 860 goto out; 861 862 /* success */ 863 r = 0; 864 *optsp = opts; 865 opts = NULL; 866 out: 867 sshauthopt_free(opts); 868 return r; 869 } 870