crypto/openssh/auth-options.c

   1 /* $OpenBSD: auth-options.c,v 1.92 2020/03/06 18:15:38 markus 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 "includes.h"
  19
  20 #include <sys/types.h>
  21
  22 #include <stdlib.h>
  23 #include <netdb.h>
  24 #include <pwd.h>
  25 #include <string.h>
  26 #include <stdio.h>
  27 #include <stdarg.h>
  28 #include <ctype.h>
  29 #include <limits.h>
  30
  31 #include "openbsd-compat/sys-queue.h"
  32
  33 #include "xmalloc.h"
  34 #include "ssherr.h"
  35 #include "log.h"
  36 #include "sshbuf.h"
  37 #include "misc.h"
  38 #include "sshkey.h"
  39 #include "match.h"
  40 #include "ssh2.h"
  41 #include "auth-options.h"
  42
  43 static int
  44 dup_strings(char ***dstp, size_t *ndstp, char **src, size_t nsrc)
  45 {
  46         char **dst;
  47         size_t i, j;
  48
  49         *dstp = NULL;
  50         *ndstp = 0;
  51         if (nsrc == 0)
  52                 return 0;
  53
  54         if ((dst = calloc(nsrc, sizeof(*src))) == NULL)
  55                 return -1;
  56         for (i = 0; i < nsrc; i++) {
  57                 if ((dst[i] = strdup(src[i])) == NULL) {
  58                         for (j = 0; j < i; j++)
  59                                 free(dst[j]);
  60                         free(dst);
  61                         return -1;
  62                 }
  63         }
  64         /* success */
  65         *dstp = dst;
  66         *ndstp = nsrc;
  67         return 0;
  68 }
  69
  70 #define OPTIONS_CRITICAL        1
  71 #define OPTIONS_EXTENSIONS      2
  72 static int
  73 cert_option_list(struct sshauthopt *opts, struct sshbuf *oblob,
  74     u_int which, int crit)
  75 {
  76         char *command, *allowed;
  77         char *name = NULL;
  78         struct sshbuf *c = NULL, *data = NULL;
  79         int r, ret = -1, found;
  80
  81         if ((c = sshbuf_fromb(oblob)) == NULL) {
  82                 error("%s: sshbuf_fromb failed", __func__);
  83                 goto out;
  84         }
  85
  86         while (sshbuf_len(c) > 0) {
  87                 sshbuf_free(data);
  88                 data = NULL;
  89                 if ((r = sshbuf_get_cstring(c, &name, NULL)) != 0 ||
  90                     (r = sshbuf_froms(c, &data)) != 0) {
  91                         error("Unable to parse certificate options: %s",
  92                             ssh_err(r));
  93                         goto out;
  94                 }
  95                 debug3("found certificate option \"%.100s\" len %zu",
  96                     name, sshbuf_len(data));
  97                 found = 0;
  98                 if ((which & OPTIONS_EXTENSIONS) != 0) {
  99                         if (strcmp(name, "no-touch-required") == 0) {
 100                                 opts->no_require_user_presence = 1;
 101                                 found = 1;
 102                         } else if (strcmp(name, "permit-X11-forwarding") == 0) {
 103                                 opts->permit_x11_forwarding_flag = 1;
 104                                 found = 1;
 105                         } else if (strcmp(name,
 106                             "permit-agent-forwarding") == 0) {
 107                                 opts->permit_agent_forwarding_flag = 1;
 108                                 found = 1;
 109                         } else if (strcmp(name,
 110                             "permit-port-forwarding") == 0) {
 111                                 opts->permit_port_forwarding_flag = 1;
 112                                 found = 1;
 113                         } else if (strcmp(name, "permit-pty") == 0) {
 114                                 opts->permit_pty_flag = 1;
 115                                 found = 1;
 116                         } else if (strcmp(name, "permit-user-rc") == 0) {
 117                                 opts->permit_user_rc = 1;
 118                                 found = 1;
 119                         }
 120                 }
 121                 if (!found && (which & OPTIONS_CRITICAL) != 0) {
 122                         if (strcmp(name, "force-command") == 0) {
 123                                 if ((r = sshbuf_get_cstring(data, &command,
 124                                     NULL)) != 0) {
 125                                         error("Unable to parse \"%s\" "
 126                                             "section: %s", name, ssh_err(r));
 127                                         goto out;
 128                                 }
 129                                 if (opts->force_command != NULL) {
 130                                         error("Certificate has multiple "
 131                                             "force-command options");
 132                                         free(command);
 133                                         goto out;
 134                                 }
 135                                 opts->force_command = command;
 136                                 found = 1;
 137                         }
 138                         if (strcmp(name, "source-address") == 0) {
 139                                 if ((r = sshbuf_get_cstring(data, &allowed,
 140                                     NULL)) != 0) {
 141                                         error("Unable to parse \"%s\" "
 142                                             "section: %s", name, ssh_err(r));
 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 = hpdelim(&cp);
 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
 327         if (errstrp != NULL)
 328                 *errstrp = NULL;
 329         if ((ret = sshauthopt_new_with_keys_defaults()) == NULL)
 330                 goto alloc_fail;
 331
 332         if (opts == NULL)
 333                 return ret;
 334
 335         while (*opts && *opts != ' ' && *opts != '\t') {
 336                 /* flag options */
 337                 if ((r = opt_flag("restrict", 0, &opts)) != -1) {
 338                         ret->restricted = 1;
 339                         ret->permit_port_forwarding_flag = 0;
 340                         ret->permit_agent_forwarding_flag = 0;
 341                         ret->permit_x11_forwarding_flag = 0;
 342                         ret->permit_pty_flag = 0;
 343                         ret->permit_user_rc = 0;
 344                 } else if ((r = opt_flag("cert-authority", 0, &opts)) != -1) {
 345                         ret->cert_authority = r;
 346                 } else if ((r = opt_flag("port-forwarding", 1, &opts)) != -1) {
 347                         ret->permit_port_forwarding_flag = r == 1;
 348                 } else if ((r = opt_flag("agent-forwarding", 1, &opts)) != -1) {
 349                         ret->permit_agent_forwarding_flag = r == 1;
 350                 } else if ((r = opt_flag("x11-forwarding", 1, &opts)) != -1) {
 351                         ret->permit_x11_forwarding_flag = r == 1;
 352                 } else if ((r = opt_flag("touch-required", 1, &opts)) != -1) {
 353                         ret->no_require_user_presence = r != 1; /* NB. flip */
 354                 } else if ((r = opt_flag("pty", 1, &opts)) != -1) {
 355                         ret->permit_pty_flag = r == 1;
 356                 } else if ((r = opt_flag("user-rc", 1, &opts)) != -1) {
 357                         ret->permit_user_rc = r == 1;
 358                 } else if (opt_match(&opts, "command")) {
 359                         if (ret->force_command != NULL) {
 360                                 errstr = "multiple \"command\" clauses";
 361                                 goto fail;
 362                         }
 363                         ret->force_command = opt_dequote(&opts, &errstr);
 364                         if (ret->force_command == NULL)
 365                                 goto fail;
 366                 } else if (opt_match(&opts, "principals")) {
 367                         if (ret->cert_principals != NULL) {
 368                                 errstr = "multiple \"principals\" clauses";
 369                                 goto fail;
 370                         }
 371                         ret->cert_principals = opt_dequote(&opts, &errstr);
 372                         if (ret->cert_principals == NULL)
 373                                 goto fail;
 374                 } else if (opt_match(&opts, "from")) {
 375                         if (ret->required_from_host_keys != NULL) {
 376                                 errstr = "multiple \"from\" clauses";
 377                                 goto fail;
 378                         }
 379                         ret->required_from_host_keys = opt_dequote(&opts,
 380                             &errstr);
 381                         if (ret->required_from_host_keys == NULL)
 382                                 goto fail;
 383                 } else if (opt_match(&opts, "expiry-time")) {
 384                         if ((opt = opt_dequote(&opts, &errstr)) == NULL)
 385                                 goto fail;
 386                         if (parse_absolute_time(opt, &valid_before) != 0 ||
 387                             valid_before == 0) {
 388                                 free(opt);
 389                                 errstr = "invalid expires time";
 390                                 goto fail;
 391                         }
 392                         free(opt);
 393                         if (ret->valid_before == 0 ||
 394                             valid_before < ret->valid_before)
 395                                 ret->valid_before = valid_before;
 396                 } else if (opt_match(&opts, "environment")) {
 397                         if (ret->nenv > INT_MAX) {
 398                                 errstr = "too many environment strings";
 399                                 goto fail;
 400                         }
 401                         if ((opt = opt_dequote(&opts, &errstr)) == NULL)
 402                                 goto fail;
 403                         /* env name must be alphanumeric and followed by '=' */
 404                         if ((tmp = strchr(opt, '=')) == NULL) {
 405                                 free(opt);
 406                                 errstr = "invalid environment string";
 407                                 goto fail;
 408                         }
 409                         if ((cp = strdup(opt)) == NULL)
 410                                 goto alloc_fail;
 411                         cp[tmp - opt] = '\0'; /* truncate at '=' */
 412                         if (!valid_env_name(cp)) {
 413                                 free(cp);
 414                                 free(opt);
 415                                 errstr = "invalid environment string";
 416                                 goto fail;
 417                         }
 418                         free(cp);
 419                         /* Append it. */
 420                         oarray = ret->env;
 421                         if ((ret->env = recallocarray(ret->env, ret->nenv,
 422                             ret->nenv + 1, sizeof(*ret->env))) == NULL) {
 423                                 free(opt);
 424                                 ret->env = oarray; /* put it back for cleanup */
 425                                 goto alloc_fail;
 426                         }
 427                         ret->env[ret->nenv++] = opt;
 428                 } else if (opt_match(&opts, "permitopen")) {
 429                         if (handle_permit(&opts, 0, &ret->permitopen,
 430                             &ret->npermitopen, &errstr) != 0)
 431                                 goto fail;
 432                 } else if (opt_match(&opts, "permitlisten")) {
 433                         if (handle_permit(&opts, 1, &ret->permitlisten,
 434                             &ret->npermitlisten, &errstr) != 0)
 435                                 goto fail;
 436                 } else if (opt_match(&opts, "tunnel")) {
 437                         if ((opt = opt_dequote(&opts, &errstr)) == NULL)
 438                                 goto fail;
 439                         ret->force_tun_device = a2tun(opt, NULL);
 440                         free(opt);
 441                         if (ret->force_tun_device == SSH_TUNID_ERR) {
 442                                 errstr = "invalid tun device";
 443                                 goto fail;
 444                         }
 445                 }
 446                 /*
 447                  * Skip the comma, and move to the next option
 448                  * (or break out if there are no more).
 449                  */
 450                 if (*opts == '\0' || *opts == ' ' || *opts == '\t')
 451                         break;          /* End of options. */
 452                 /* Anything other than a comma is an unknown option */
 453                 if (*opts != ',') {
 454                         errstr = "unknown key option";
 455                         goto fail;
 456                 }
 457                 opts++;
 458                 if (*opts == '\0') {
 459                         errstr = "unexpected end-of-options";
 460                         goto fail;
 461                 }
 462         }
 463
 464         /* success */
 465         if (errstrp != NULL)
 466                 *errstrp = NULL;
 467         return ret;
 468
 469 alloc_fail:
 470         errstr = "memory allocation failed";
 471 fail:
 472         sshauthopt_free(ret);
 473         if (errstrp != NULL)
 474                 *errstrp = errstr;
 475         return NULL;
 476 }
 477
 478 struct sshauthopt *
 479 sshauthopt_from_cert(struct sshkey *k)
 480 {
 481         struct sshauthopt *ret;
 482
 483         if (k == NULL || !sshkey_type_is_cert(k->type) || k->cert == NULL ||
 484             k->cert->type != SSH2_CERT_TYPE_USER)
 485                 return NULL;
 486
 487         if ((ret = sshauthopt_new()) == NULL)
 488                 return NULL;
 489
 490         /* Handle options and critical extensions separately */
 491         if (cert_option_list(ret, k->cert->critical,
 492             OPTIONS_CRITICAL, 1) == -1) {
 493                 sshauthopt_free(ret);
 494                 return NULL;
 495         }
 496         if (cert_option_list(ret, k->cert->extensions,
 497             OPTIONS_EXTENSIONS, 0) == -1) {
 498                 sshauthopt_free(ret);
 499                 return NULL;
 500         }
 501         /* success */
 502         return ret;
 503 }
 504
 505 /*
 506  * Merges "additional" options to "primary" and returns the result.
 507  * NB. Some options from primary have primacy.
 508  */
 509 struct sshauthopt *
 510 sshauthopt_merge(const struct sshauthopt *primary,
 511     const struct sshauthopt *additional, const char **errstrp)
 512 {
 513         struct sshauthopt *ret;
 514         const char *errstr = "internal error";
 515         const char *tmp;
 516
 517         if (errstrp != NULL)
 518                 *errstrp = NULL;
 519
 520         if ((ret = sshauthopt_new()) == NULL)
 521                 goto alloc_fail;
 522
 523         /* cert_authority and cert_principals are cleared in result */
 524
 525         /* Prefer access lists from primary. */
 526         /* XXX err is both set and mismatch? */
 527         tmp = primary->required_from_host_cert;
 528         if (tmp == NULL)
 529                 tmp = additional->required_from_host_cert;
 530         if (tmp != NULL && (ret->required_from_host_cert = strdup(tmp)) == NULL)
 531                 goto alloc_fail;
 532         tmp = primary->required_from_host_keys;
 533         if (tmp == NULL)
 534                 tmp = additional->required_from_host_keys;
 535         if (tmp != NULL && (ret->required_from_host_keys = strdup(tmp)) == NULL)
 536                 goto alloc_fail;
 537
 538         /*
 539          * force_tun_device, permitopen/permitlisten and environment all
 540          * prefer the primary.
 541          */
 542         ret->force_tun_device = primary->force_tun_device;
 543         if (ret->force_tun_device == -1)
 544                 ret->force_tun_device = additional->force_tun_device;
 545         if (primary->nenv > 0) {
 546                 if (dup_strings(&ret->env, &ret->nenv,
 547                     primary->env, primary->nenv) != 0)
 548                         goto alloc_fail;
 549         } else if (additional->nenv) {
 550                 if (dup_strings(&ret->env, &ret->nenv,
 551                     additional->env, additional->nenv) != 0)
 552                         goto alloc_fail;
 553         }
 554         if (primary->npermitopen > 0) {
 555                 if (dup_strings(&ret->permitopen, &ret->npermitopen,
 556                     primary->permitopen, primary->npermitopen) != 0)
 557                         goto alloc_fail;
 558         } else if (additional->npermitopen > 0) {
 559                 if (dup_strings(&ret->permitopen, &ret->npermitopen,
 560                     additional->permitopen, additional->npermitopen) != 0)
 561                         goto alloc_fail;
 562         }
 563
 564         if (primary->npermitlisten > 0) {
 565                 if (dup_strings(&ret->permitlisten, &ret->npermitlisten,
 566                     primary->permitlisten, primary->npermitlisten) != 0)
 567                         goto alloc_fail;
 568         } else if (additional->npermitlisten > 0) {
 569                 if (dup_strings(&ret->permitlisten, &ret->npermitlisten,
 570                     additional->permitlisten, additional->npermitlisten) != 0)
 571                         goto alloc_fail;
 572         }
 573
 574 #define OPTFLAG_AND(x) ret->x = (primary->x == 1) && (additional->x == 1)
 575         /* Permissive flags are logical-AND (i.e. must be set in both) */
 576         OPTFLAG_AND(permit_port_forwarding_flag);
 577         OPTFLAG_AND(permit_agent_forwarding_flag);
 578         OPTFLAG_AND(permit_x11_forwarding_flag);
 579         OPTFLAG_AND(permit_pty_flag);
 580         OPTFLAG_AND(permit_user_rc);
 581         OPTFLAG_AND(no_require_user_presence);
 582 #undef OPTFLAG_AND
 583
 584         /* Earliest expiry time should win */
 585         if (primary->valid_before != 0)
 586                 ret->valid_before = primary->valid_before;
 587         if (additional->valid_before != 0 &&
 588             additional->valid_before < ret->valid_before)
 589                 ret->valid_before = additional->valid_before;
 590
 591         /*
 592          * When both multiple forced-command are specified, only
 593          * proceed if they are identical, otherwise fail.
 594          */
 595         if (primary->force_command != NULL &&
 596             additional->force_command != NULL) {
 597                 if (strcmp(primary->force_command,
 598                     additional->force_command) == 0) {
 599                         /* ok */
 600                         ret->force_command = strdup(primary->force_command);
 601                         if (ret->force_command == NULL)
 602                                 goto alloc_fail;
 603                 } else {
 604                         errstr = "forced command options do not match";
 605                         goto fail;
 606                 }
 607         } else if (primary->force_command != NULL) {
 608                 if ((ret->force_command = strdup(
 609                     primary->force_command)) == NULL)
 610                         goto alloc_fail;
 611         } else if (additional->force_command != NULL) {
 612                 if ((ret->force_command = strdup(
 613                     additional->force_command)) == NULL)
 614                         goto alloc_fail;
 615         }
 616         /* success */
 617         if (errstrp != NULL)
 618                 *errstrp = NULL;
 619         return ret;
 620
 621  alloc_fail:
 622         errstr = "memory allocation failed";
 623  fail:
 624         if (errstrp != NULL)
 625                 *errstrp = errstr;
 626         sshauthopt_free(ret);
 627         return NULL;
 628 }
 629
 630 /*
 631  * Copy options
 632  */
 633 struct sshauthopt *
 634 sshauthopt_copy(const struct sshauthopt *orig)
 635 {
 636         struct sshauthopt *ret;
 637
 638         if ((ret = sshauthopt_new()) == NULL)
 639                 return NULL;
 640
 641 #define OPTSCALAR(x) ret->x = orig->x
 642         OPTSCALAR(permit_port_forwarding_flag);
 643         OPTSCALAR(permit_agent_forwarding_flag);
 644         OPTSCALAR(permit_x11_forwarding_flag);
 645         OPTSCALAR(permit_pty_flag);
 646         OPTSCALAR(permit_user_rc);
 647         OPTSCALAR(restricted);
 648         OPTSCALAR(cert_authority);
 649         OPTSCALAR(force_tun_device);
 650         OPTSCALAR(valid_before);
 651         OPTSCALAR(no_require_user_presence);
 652 #undef OPTSCALAR
 653 #define OPTSTRING(x) \
 654         do { \
 655                 if (orig->x != NULL && (ret->x = strdup(orig->x)) == NULL) { \
 656                         sshauthopt_free(ret); \
 657                         return NULL; \
 658                 } \
 659         } while (0)
 660         OPTSTRING(cert_principals);
 661         OPTSTRING(force_command);
 662         OPTSTRING(required_from_host_cert);
 663         OPTSTRING(required_from_host_keys);
 664 #undef OPTSTRING
 665
 666         if (dup_strings(&ret->env, &ret->nenv, orig->env, orig->nenv) != 0 ||
 667             dup_strings(&ret->permitopen, &ret->npermitopen,
 668             orig->permitopen, orig->npermitopen) != 0 ||
 669             dup_strings(&ret->permitlisten, &ret->npermitlisten,
 670             orig->permitlisten, orig->npermitlisten) != 0) {
 671                 sshauthopt_free(ret);
 672                 return NULL;
 673         }
 674         return ret;
 675 }
 676
 677 static int
 678 serialise_array(struct sshbuf *m, char **a, size_t n)
 679 {
 680         struct sshbuf *b;
 681         size_t i;
 682         int r;
 683
 684         if (n > INT_MAX)
 685                 return SSH_ERR_INTERNAL_ERROR;
 686
 687         if ((b = sshbuf_new()) == NULL) {
 688                 return SSH_ERR_ALLOC_FAIL;
 689         }
 690         for (i = 0; i < n; i++) {
 691                 if ((r = sshbuf_put_cstring(b, a[i])) != 0) {
 692                         sshbuf_free(b);
 693                         return r;
 694                 }
 695         }
 696         if ((r = sshbuf_put_u32(m, n)) != 0 ||
 697             (r = sshbuf_put_stringb(m, b)) != 0) {
 698                 sshbuf_free(b);
 699                 return r;
 700         }
 701         /* success */
 702         return 0;
 703 }
 704
 705 static int
 706 deserialise_array(struct sshbuf *m, char ***ap, size_t *np)
 707 {
 708         char **a = NULL;
 709         size_t i, n = 0;
 710         struct sshbuf *b = NULL;
 711         u_int tmp;
 712         int r = SSH_ERR_INTERNAL_ERROR;
 713
 714         if ((r = sshbuf_get_u32(m, &tmp)) != 0 ||
 715             (r = sshbuf_froms(m, &b)) != 0)
 716                 goto out;
 717         if (tmp > INT_MAX) {
 718                 r = SSH_ERR_INVALID_FORMAT;
 719                 goto out;
 720         }
 721         n = tmp;
 722         if (n > 0 && (a = calloc(n, sizeof(*a))) == NULL) {
 723                 r = SSH_ERR_ALLOC_FAIL;
 724                 goto out;
 725         }
 726         for (i = 0; i < n; i++) {
 727                 if ((r = sshbuf_get_cstring(b, &a[i], NULL)) != 0)
 728                         goto out;
 729         }
 730         /* success */
 731         r = 0;
 732         *ap = a;
 733         a = NULL;
 734         *np = n;
 735         n = 0;
 736  out:
 737         if (a != NULL) {
 738                 for (i = 0; i < n; i++)
 739                         free(a[i]);
 740                 free(a);
 741         }
 742         sshbuf_free(b);
 743         return r;
 744 }
 745
 746 static int
 747 serialise_nullable_string(struct sshbuf *m, const char *s)
 748 {
 749         int r;
 750
 751         if ((r = sshbuf_put_u8(m, s == NULL)) != 0 ||
 752             (r = sshbuf_put_cstring(m, s)) != 0)
 753                 return r;
 754         return 0;
 755 }
 756
 757 static int
 758 deserialise_nullable_string(struct sshbuf *m, char **sp)
 759 {
 760         int r;
 761         u_char flag;
 762
 763         *sp = NULL;
 764         if ((r = sshbuf_get_u8(m, &flag)) != 0 ||
 765             (r = sshbuf_get_cstring(m, flag ? NULL : sp, NULL)) != 0)
 766                 return r;
 767         return 0;
 768 }
 769
 770 int
 771 sshauthopt_serialise(const struct sshauthopt *opts, struct sshbuf *m,
 772     int untrusted)
 773 {
 774         int r = SSH_ERR_INTERNAL_ERROR;
 775
 776         /* Flag options */
 777         if ((r = sshbuf_put_u8(m, opts->permit_port_forwarding_flag)) != 0 ||
 778             (r = sshbuf_put_u8(m, opts->permit_agent_forwarding_flag)) != 0 ||
 779             (r = sshbuf_put_u8(m, opts->permit_x11_forwarding_flag)) != 0 ||
 780             (r = sshbuf_put_u8(m, opts->permit_pty_flag)) != 0 ||
 781             (r = sshbuf_put_u8(m, opts->permit_user_rc)) != 0 ||
 782             (r = sshbuf_put_u8(m, opts->restricted)) != 0 ||
 783             (r = sshbuf_put_u8(m, opts->cert_authority)) != 0 ||
 784             (r = sshbuf_put_u8(m, opts->no_require_user_presence)) != 0)
 785                 return r;
 786
 787         /* Simple integer options */
 788         if ((r = sshbuf_put_u64(m, opts->valid_before)) != 0)
 789                 return r;
 790
 791         /* tunnel number can be negative to indicate "unset" */
 792         if ((r = sshbuf_put_u8(m, opts->force_tun_device == -1)) != 0 ||
 793             (r = sshbuf_put_u32(m, (opts->force_tun_device < 0) ?
 794             0 : (u_int)opts->force_tun_device)) != 0)
 795                 return r;
 796
 797         /* String options; these may be NULL */
 798         if ((r = serialise_nullable_string(m,
 799             untrusted ? "yes" : opts->cert_principals)) != 0 ||
 800             (r = serialise_nullable_string(m,
 801             untrusted ? "true" : opts->force_command)) != 0 ||
 802             (r = serialise_nullable_string(m,
 803             untrusted ? NULL : opts->required_from_host_cert)) != 0 ||
 804             (r = serialise_nullable_string(m,
 805              untrusted ? NULL : opts->required_from_host_keys)) != 0)
 806                 return r;
 807
 808         /* Array options */
 809         if ((r = serialise_array(m, opts->env,
 810             untrusted ? 0 : opts->nenv)) != 0 ||
 811             (r = serialise_array(m, opts->permitopen,
 812             untrusted ? 0 : opts->npermitopen)) != 0 ||
 813             (r = serialise_array(m, opts->permitlisten,
 814             untrusted ? 0 : opts->npermitlisten)) != 0)
 815                 return r;
 816
 817         /* success */
 818         return 0;
 819 }
 820
 821 int
 822 sshauthopt_deserialise(struct sshbuf *m, struct sshauthopt **optsp)
 823 {
 824         struct sshauthopt *opts = NULL;
 825         int r = SSH_ERR_INTERNAL_ERROR;
 826         u_char f;
 827         u_int tmp;
 828
 829         if ((opts = calloc(1, sizeof(*opts))) == NULL)
 830                 return SSH_ERR_ALLOC_FAIL;
 831
 832         /* Flag options */
 833 #define OPT_FLAG(x) \
 834         do { \
 835                 if ((r = sshbuf_get_u8(m, &f)) != 0) \
 836                         goto out; \
 837                 opts->x = f; \
 838         } while (0)
 839         OPT_FLAG(permit_port_forwarding_flag);
 840         OPT_FLAG(permit_agent_forwarding_flag);
 841         OPT_FLAG(permit_x11_forwarding_flag);
 842         OPT_FLAG(permit_pty_flag);
 843         OPT_FLAG(permit_user_rc);
 844         OPT_FLAG(restricted);
 845         OPT_FLAG(cert_authority);
 846         OPT_FLAG(no_require_user_presence);
 847 #undef OPT_FLAG
 848
 849         /* Simple integer options */
 850         if ((r = sshbuf_get_u64(m, &opts->valid_before)) != 0)
 851                 goto out;
 852
 853         /* tunnel number can be negative to indicate "unset" */
 854         if ((r = sshbuf_get_u8(m, &f)) != 0 ||
 855             (r = sshbuf_get_u32(m, &tmp)) != 0)
 856                 goto out;
 857         opts->force_tun_device = f ? -1 : (int)tmp;
 858
 859         /* String options may be NULL */
 860         if ((r = deserialise_nullable_string(m, &opts->cert_principals)) != 0 ||
 861             (r = deserialise_nullable_string(m, &opts->force_command)) != 0 ||
 862             (r = deserialise_nullable_string(m,
 863             &opts->required_from_host_cert)) != 0 ||
 864             (r = deserialise_nullable_string(m,
 865             &opts->required_from_host_keys)) != 0)
 866                 goto out;
 867
 868         /* Array options */
 869         if ((r = deserialise_array(m, &opts->env, &opts->nenv)) != 0 ||
 870             (r = deserialise_array(m,
 871             &opts->permitopen, &opts->npermitopen)) != 0 ||
 872             (r = deserialise_array(m,
 873             &opts->permitlisten, &opts->npermitlisten)) != 0)
 874                 goto out;
 875
 876         /* success */
 877         r = 0;
 878         *optsp = opts;
 879         opts = NULL;
 880  out:
 881         sshauthopt_free(opts);
 882         return r;
 883 }