crypto/openssh/auth-options.c

   1 /* $OpenBSD: auth-options.c,v 1.98 2022/02/08 08:59:12 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 "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_f("sshbuf_fromb failed");
  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_r(r, "Unable to parse certificate options");
  92                         goto out;
  93                 }
  94                 debug3("found certificate option \"%.100s\" len %zu",
  95                     name, sshbuf_len(data));
  96                 found = 0;
  97                 if ((which & OPTIONS_EXTENSIONS) != 0) {
  98                         if (strcmp(name, "no-touch-required") == 0) {
  99                                 opts->no_require_user_presence = 1;
 100                                 found = 1;
 101                         } else if (strcmp(name, "permit-X11-forwarding") == 0) {
 102                                 opts->permit_x11_forwarding_flag = 1;
 103                                 found = 1;
 104                         } else if (strcmp(name,
 105                             "permit-agent-forwarding") == 0) {
 106                                 opts->permit_agent_forwarding_flag = 1;
 107                                 found = 1;
 108                         } else if (strcmp(name,
 109                             "permit-port-forwarding") == 0) {
 110                                 opts->permit_port_forwarding_flag = 1;
 111                                 found = 1;
 112                         } else if (strcmp(name, "permit-pty") == 0) {
 113                                 opts->permit_pty_flag = 1;
 114                                 found = 1;
 115                         } else if (strcmp(name, "permit-user-rc") == 0) {
 116                                 opts->permit_user_rc = 1;
 117                                 found = 1;
 118                         }
 119                 }
 120                 if (!found && (which & OPTIONS_CRITICAL) != 0) {
 121                         if (strcmp(name, "verify-required") == 0) {
 122                                 opts->require_verify = 1;
 123                                 found = 1;
 124                         } else if (strcmp(name, "force-command") == 0) {
 125                                 if ((r = sshbuf_get_cstring(data, &command,
 126                                     NULL)) != 0) {
 127                                         error_r(r, "Unable to parse \"%s\" "
 128                                             "section", name);
 129                                         goto out;
 130                                 }
 131                                 if (opts->force_command != NULL) {
 132                                         error("Certificate has multiple "
 133                                             "force-command options");
 134                                         free(command);
 135                                         goto out;
 136                                 }
 137                                 opts->force_command = command;
 138                                 found = 1;
 139                         } else if (strcmp(name, "source-address") == 0) {
 140                                 if ((r = sshbuf_get_cstring(data, &allowed,
 141                                     NULL)) != 0) {
 142                                         error_r(r, "Unable to parse \"%s\" "
 143                                             "section", name);
 144                                         goto out;
 145                                 }
 146                                 if (opts->required_from_host_cert != NULL) {
 147                                         error("Certificate has multiple "
 148                                             "source-address options");
 149                                         free(allowed);
 150                                         goto out;
 151                                 }
 152                                 /* Check syntax */
 153                                 if (addr_match_cidr_list(NULL, allowed) == -1) {
 154                                         error("Certificate source-address "
 155                                             "contents invalid");
 156                                         goto out;
 157                                 }
 158                                 opts->required_from_host_cert = allowed;
 159                                 found = 1;
 160                         }
 161                 }
 162
 163                 if (!found) {
 164                         if (crit) {
 165                                 error("Certificate critical option \"%s\" "
 166                                     "is not supported", name);
 167                                 goto out;
 168                         } else {
 169                                 logit("Certificate extension \"%s\" "
 170                                     "is not supported", name);
 171                         }
 172                 } else if (sshbuf_len(data) != 0) {
 173                         error("Certificate option \"%s\" corrupt "
 174                             "(extra data)", name);
 175                         goto out;
 176                 }
 177                 free(name);
 178                 name = NULL;
 179         }
 180         /* successfully parsed all options */
 181         ret = 0;
 182
 183  out:
 184         free(name);
 185         sshbuf_free(data);
 186         sshbuf_free(c);
 187         return ret;
 188 }
 189
 190 struct sshauthopt *
 191 sshauthopt_new(void)
 192 {
 193         struct sshauthopt *ret;
 194
 195         if ((ret = calloc(1, sizeof(*ret))) == NULL)
 196                 return NULL;
 197         ret->force_tun_device = -1;
 198         return ret;
 199 }
 200
 201 void
 202 sshauthopt_free(struct sshauthopt *opts)
 203 {
 204         size_t i;
 205
 206         if (opts == NULL)
 207                 return;
 208
 209         free(opts->cert_principals);
 210         free(opts->force_command);
 211         free(opts->required_from_host_cert);
 212         free(opts->required_from_host_keys);
 213
 214         for (i = 0; i < opts->nenv; i++)
 215                 free(opts->env[i]);
 216         free(opts->env);
 217
 218         for (i = 0; i < opts->npermitopen; i++)
 219                 free(opts->permitopen[i]);
 220         free(opts->permitopen);
 221
 222         for (i = 0; i < opts->npermitlisten; i++)
 223                 free(opts->permitlisten[i]);
 224         free(opts->permitlisten);
 225
 226         freezero(opts, sizeof(*opts));
 227 }
 228
 229 struct sshauthopt *
 230 sshauthopt_new_with_keys_defaults(void)
 231 {
 232         struct sshauthopt *ret = NULL;
 233
 234         if ((ret = sshauthopt_new()) == NULL)
 235                 return NULL;
 236
 237         /* Defaults for authorized_keys flags */
 238         ret->permit_port_forwarding_flag = 1;
 239         ret->permit_agent_forwarding_flag = 1;
 240         ret->permit_x11_forwarding_flag = 1;
 241         ret->permit_pty_flag = 1;
 242         ret->permit_user_rc = 1;
 243         return ret;
 244 }
 245
 246 /*
 247  * Parse and record a permitopen/permitlisten directive.
 248  * Return 0 on success. Return -1 on failure and sets *errstrp to error reason.
 249  */
 250 static int
 251 handle_permit(const char **optsp, int allow_bare_port,
 252     char ***permitsp, size_t *npermitsp, const char **errstrp)
 253 {
 254         char *opt, *tmp, *cp, *host, **permits = *permitsp;
 255         size_t npermits = *npermitsp;
 256         const char *errstr = "unknown error";
 257
 258         if (npermits > SSH_AUTHOPT_PERMIT_MAX) {
 259                 *errstrp = "too many permission directives";
 260                 return -1;
 261         }
 262         if ((opt = opt_dequote(optsp, &errstr)) == NULL) {
 263                 return -1;
 264         }
 265         if (allow_bare_port && strchr(opt, ':') == NULL) {
 266                 /*
 267                  * Allow a bare port number in permitlisten to indicate a
 268                  * listen_host wildcard.
 269                  */
 270                 if (asprintf(&tmp, "*:%s", opt) == -1) {
 271                         free(opt);
 272                         *errstrp = "memory allocation failed";
 273                         return -1;
 274                 }
 275                 free(opt);
 276                 opt = tmp;
 277         }
 278         if ((tmp = strdup(opt)) == NULL) {
 279                 free(opt);
 280                 *errstrp = "memory allocation failed";
 281                 return -1;
 282         }
 283         cp = tmp;
 284         /* validate syntax before recording it. */
 285         host = hpdelim2(&cp, NULL);
 286         if (host == NULL || strlen(host) >= NI_MAXHOST) {
 287                 free(tmp);
 288                 free(opt);
 289                 *errstrp = "invalid permission hostname";
 290                 return -1;
 291         }
 292         /*
 293          * don't want to use permitopen_port to avoid
 294          * dependency on channels.[ch] here.
 295          */
 296         if (cp == NULL ||
 297             (strcmp(cp, "*") != 0 && a2port(cp) <= 0)) {
 298                 free(tmp);
 299                 free(opt);
 300                 *errstrp = "invalid permission port";
 301                 return -1;
 302         }
 303         /* XXX - add streamlocal support */
 304         free(tmp);
 305         /* Record it */
 306         if ((permits = recallocarray(permits, npermits, npermits + 1,
 307             sizeof(*permits))) == NULL) {
 308                 free(opt);
 309                 /* NB. don't update *permitsp if alloc fails */
 310                 *errstrp = "memory allocation failed";
 311                 return -1;
 312         }
 313         permits[npermits++] = opt;
 314         *permitsp = permits;
 315         *npermitsp = npermits;
 316         return 0;
 317 }
 318
 319 struct sshauthopt *
 320 sshauthopt_parse(const char *opts, const char **errstrp)
 321 {
 322         char **oarray, *opt, *cp, *tmp;
 323         int r;
 324         struct sshauthopt *ret = NULL;
 325         const char *errstr = "unknown error";
 326         uint64_t valid_before;
 327         size_t i, l;
 328
 329         if (errstrp != NULL)
 330                 *errstrp = NULL;
 331         if ((ret = sshauthopt_new_with_keys_defaults()) == NULL)
 332                 goto alloc_fail;
 333
 334         if (opts == NULL)
 335                 return ret;
 336
 337         while (*opts && *opts != ' ' && *opts != '\t') {
 338                 /* flag options */
 339                 if ((r = opt_flag("restrict", 0, &opts)) != -1) {
 340                         ret->restricted = 1;
 341                         ret->permit_port_forwarding_flag = 0;
 342                         ret->permit_agent_forwarding_flag = 0;
 343                         ret->permit_x11_forwarding_flag = 0;
 344                         ret->permit_pty_flag = 0;
 345                         ret->permit_user_rc = 0;
 346                 } else if ((r = opt_flag("cert-authority", 0, &opts)) != -1) {
 347                         ret->cert_authority = r;
 348                 } else if ((r = opt_flag("port-forwarding", 1, &opts)) != -1) {
 349                         ret->permit_port_forwarding_flag = r == 1;
 350                 } else if ((r = opt_flag("agent-forwarding", 1, &opts)) != -1) {
 351                         ret->permit_agent_forwarding_flag = r == 1;
 352                 } else if ((r = opt_flag("x11-forwarding", 1, &opts)) != -1) {
 353                         ret->permit_x11_forwarding_flag = r == 1;
 354                 } else if ((r = opt_flag("touch-required", 1, &opts)) != -1) {
 355                         ret->no_require_user_presence = r != 1; /* NB. flip */
 356                 } else if ((r = opt_flag("verify-required", 1, &opts)) != -1) {
 357                         ret->require_verify = r == 1;
 358                 } else if ((r = opt_flag("pty", 1, &opts)) != -1) {
 359                         ret->permit_pty_flag = r == 1;
 360                 } else if ((r = opt_flag("user-rc", 1, &opts)) != -1) {
 361                         ret->permit_user_rc = r == 1;
 362                 } else if (opt_match(&opts, "command")) {
 363                         if (ret->force_command != NULL) {
 364                                 errstr = "multiple \"command\" clauses";
 365                                 goto fail;
 366                         }
 367                         ret->force_command = opt_dequote(&opts, &errstr);
 368                         if (ret->force_command == NULL)
 369                                 goto fail;
 370                 } else if (opt_match(&opts, "principals")) {
 371                         if (ret->cert_principals != NULL) {
 372                                 errstr = "multiple \"principals\" clauses";
 373                                 goto fail;
 374                         }
 375                         ret->cert_principals = opt_dequote(&opts, &errstr);
 376                         if (ret->cert_principals == NULL)
 377                                 goto fail;
 378                 } else if (opt_match(&opts, "from")) {
 379                         if (ret->required_from_host_keys != NULL) {
 380                                 errstr = "multiple \"from\" clauses";
 381                                 goto fail;
 382                         }
 383                         ret->required_from_host_keys = opt_dequote(&opts,
 384                             &errstr);
 385                         if (ret->required_from_host_keys == NULL)
 386                                 goto fail;
 387                 } else if (opt_match(&opts, "expiry-time")) {
 388                         if ((opt = opt_dequote(&opts, &errstr)) == NULL)
 389                                 goto fail;
 390                         if (parse_absolute_time(opt, &valid_before) != 0 ||
 391                             valid_before == 0) {
 392                                 free(opt);
 393                                 errstr = "invalid expires time";
 394                                 goto fail;
 395                         }
 396                         free(opt);
 397                         if (ret->valid_before == 0 ||
 398                             valid_before < ret->valid_before)
 399                                 ret->valid_before = valid_before;
 400                 } else if (opt_match(&opts, "environment")) {
 401                         if (ret->nenv > SSH_AUTHOPT_ENV_MAX) {
 402                                 errstr = "too many environment strings";
 403                                 goto fail;
 404                         }
 405                         if ((opt = opt_dequote(&opts, &errstr)) == NULL)
 406                                 goto fail;
 407                         /* env name must be alphanumeric and followed by '=' */
 408                         if ((tmp = strchr(opt, '=')) == NULL) {
 409                                 free(opt);
 410                                 errstr = "invalid environment string";
 411                                 goto fail;
 412                         }
 413                         if ((cp = strdup(opt)) == NULL) {
 414                                 free(opt);
 415                                 goto alloc_fail;
 416                         }
 417                         l = (size_t)(tmp - opt);
 418                         cp[l] = '\0'; /* truncate at '=' */
 419                         if (!valid_env_name(cp)) {
 420                                 free(cp);
 421                                 free(opt);
 422                                 errstr = "invalid environment string";
 423                                 goto fail;
 424                         }
 425                         /* Check for duplicates; XXX O(n*log(n)) */
 426                         for (i = 0; i < ret->nenv; i++) {
 427                                 if (strncmp(ret->env[i], cp, l) == 0 &&
 428                                     ret->env[i][l] == '=')
 429                                         break;
 430                         }
 431                         free(cp);
 432                         /* First match wins */
 433                         if (i >= ret->nenv) {
 434                                 /* Append it. */
 435                                 oarray = ret->env;
 436                                 if ((ret->env = recallocarray(ret->env,
 437                                     ret->nenv, ret->nenv + 1,
 438                                     sizeof(*ret->env))) == NULL) {
 439                                         free(opt);
 440                                         /* put it back for cleanup */
 441                                         ret->env = oarray;
 442                                         goto alloc_fail;
 443                                 }
 444                                 ret->env[ret->nenv++] = opt;
 445                                 opt = NULL; /* transferred */
 446                         }
 447                         free(opt);
 448                 } else if (opt_match(&opts, "permitopen")) {
 449                         if (handle_permit(&opts, 0, &ret->permitopen,
 450                             &ret->npermitopen, &errstr) != 0)
 451                                 goto fail;
 452                 } else if (opt_match(&opts, "permitlisten")) {
 453                         if (handle_permit(&opts, 1, &ret->permitlisten,
 454                             &ret->npermitlisten, &errstr) != 0)
 455                                 goto fail;
 456                 } else if (opt_match(&opts, "tunnel")) {
 457                         if ((opt = opt_dequote(&opts, &errstr)) == NULL)
 458                                 goto fail;
 459                         ret->force_tun_device = a2tun(opt, NULL);
 460                         free(opt);
 461                         if (ret->force_tun_device == SSH_TUNID_ERR) {
 462                                 errstr = "invalid tun device";
 463                                 goto fail;
 464                         }
 465                 }
 466                 /*
 467                  * Skip the comma, and move to the next option
 468                  * (or break out if there are no more).
 469                  */
 470                 if (*opts == '\0' || *opts == ' ' || *opts == '\t')
 471                         break;          /* End of options. */
 472                 /* Anything other than a comma is an unknown option */
 473                 if (*opts != ',') {
 474                         errstr = "unknown key option";
 475                         goto fail;
 476                 }
 477                 opts++;
 478                 if (*opts == '\0') {
 479                         errstr = "unexpected end-of-options";
 480                         goto fail;
 481                 }
 482         }
 483
 484         /* success */
 485         if (errstrp != NULL)
 486                 *errstrp = NULL;
 487         return ret;
 488
 489 alloc_fail:
 490         errstr = "memory allocation failed";
 491 fail:
 492         sshauthopt_free(ret);
 493         if (errstrp != NULL)
 494                 *errstrp = errstr;
 495         return NULL;
 496 }
 497
 498 struct sshauthopt *
 499 sshauthopt_from_cert(struct sshkey *k)
 500 {
 501         struct sshauthopt *ret;
 502
 503         if (k == NULL || !sshkey_type_is_cert(k->type) || k->cert == NULL ||
 504             k->cert->type != SSH2_CERT_TYPE_USER)
 505                 return NULL;
 506
 507         if ((ret = sshauthopt_new()) == NULL)
 508                 return NULL;
 509
 510         /* Handle options and critical extensions separately */
 511         if (cert_option_list(ret, k->cert->critical,
 512             OPTIONS_CRITICAL, 1) == -1) {
 513                 sshauthopt_free(ret);
 514                 return NULL;
 515         }
 516         if (cert_option_list(ret, k->cert->extensions,
 517             OPTIONS_EXTENSIONS, 0) == -1) {
 518                 sshauthopt_free(ret);
 519                 return NULL;
 520         }
 521         /* success */
 522         return ret;
 523 }
 524
 525 /*
 526  * Merges "additional" options to "primary" and returns the result.
 527  * NB. Some options from primary have primacy.
 528  */
 529 struct sshauthopt *
 530 sshauthopt_merge(const struct sshauthopt *primary,
 531     const struct sshauthopt *additional, const char **errstrp)
 532 {
 533         struct sshauthopt *ret;
 534         const char *errstr = "internal error";
 535         const char *tmp;
 536
 537         if (errstrp != NULL)
 538                 *errstrp = NULL;
 539
 540         if ((ret = sshauthopt_new()) == NULL)
 541                 goto alloc_fail;
 542
 543         /* cert_authority and cert_principals are cleared in result */
 544
 545         /* Prefer access lists from primary. */
 546         /* XXX err is both set and mismatch? */
 547         tmp = primary->required_from_host_cert;
 548         if (tmp == NULL)
 549                 tmp = additional->required_from_host_cert;
 550         if (tmp != NULL && (ret->required_from_host_cert = strdup(tmp)) == NULL)
 551                 goto alloc_fail;
 552         tmp = primary->required_from_host_keys;
 553         if (tmp == NULL)
 554                 tmp = additional->required_from_host_keys;
 555         if (tmp != NULL && (ret->required_from_host_keys = strdup(tmp)) == NULL)
 556                 goto alloc_fail;
 557
 558         /*
 559          * force_tun_device, permitopen/permitlisten and environment all
 560          * prefer the primary.
 561          */
 562         ret->force_tun_device = primary->force_tun_device;
 563         if (ret->force_tun_device == -1)
 564                 ret->force_tun_device = additional->force_tun_device;
 565         if (primary->nenv > 0) {
 566                 if (dup_strings(&ret->env, &ret->nenv,
 567                     primary->env, primary->nenv) != 0)
 568                         goto alloc_fail;
 569         } else if (additional->nenv) {
 570                 if (dup_strings(&ret->env, &ret->nenv,
 571                     additional->env, additional->nenv) != 0)
 572                         goto alloc_fail;
 573         }
 574         if (primary->npermitopen > 0) {
 575                 if (dup_strings(&ret->permitopen, &ret->npermitopen,
 576                     primary->permitopen, primary->npermitopen) != 0)
 577                         goto alloc_fail;
 578         } else if (additional->npermitopen > 0) {
 579                 if (dup_strings(&ret->permitopen, &ret->npermitopen,
 580                     additional->permitopen, additional->npermitopen) != 0)
 581                         goto alloc_fail;
 582         }
 583
 584         if (primary->npermitlisten > 0) {
 585                 if (dup_strings(&ret->permitlisten, &ret->npermitlisten,
 586                     primary->permitlisten, primary->npermitlisten) != 0)
 587                         goto alloc_fail;
 588         } else if (additional->npermitlisten > 0) {
 589                 if (dup_strings(&ret->permitlisten, &ret->npermitlisten,
 590                     additional->permitlisten, additional->npermitlisten) != 0)
 591                         goto alloc_fail;
 592         }
 593
 594 #define OPTFLAG_AND(x) ret->x = (primary->x == 1) && (additional->x == 1)
 595 #define OPTFLAG_OR(x) ret->x = (primary->x == 1) || (additional->x == 1)
 596         /* Permissive flags are logical-AND (i.e. must be set in both) */
 597         OPTFLAG_AND(permit_port_forwarding_flag);
 598         OPTFLAG_AND(permit_agent_forwarding_flag);
 599         OPTFLAG_AND(permit_x11_forwarding_flag);
 600         OPTFLAG_AND(permit_pty_flag);
 601         OPTFLAG_AND(permit_user_rc);
 602         OPTFLAG_AND(no_require_user_presence);
 603         /* Restrictive flags are logical-OR (i.e. must be set in either) */
 604         OPTFLAG_OR(require_verify);
 605 #undef OPTFLAG_AND
 606
 607         /* Earliest expiry time should win */
 608         if (primary->valid_before != 0)
 609                 ret->valid_before = primary->valid_before;
 610         if (additional->valid_before != 0 &&
 611             additional->valid_before < ret->valid_before)
 612                 ret->valid_before = additional->valid_before;
 613
 614         /*
 615          * When both multiple forced-command are specified, only
 616          * proceed if they are identical, otherwise fail.
 617          */
 618         if (primary->force_command != NULL &&
 619             additional->force_command != NULL) {
 620                 if (strcmp(primary->force_command,
 621                     additional->force_command) == 0) {
 622                         /* ok */
 623                         ret->force_command = strdup(primary->force_command);
 624                         if (ret->force_command == NULL)
 625                                 goto alloc_fail;
 626                 } else {
 627                         errstr = "forced command options do not match";
 628                         goto fail;
 629                 }
 630         } else if (primary->force_command != NULL) {
 631                 if ((ret->force_command = strdup(
 632                     primary->force_command)) == NULL)
 633                         goto alloc_fail;
 634         } else if (additional->force_command != NULL) {
 635                 if ((ret->force_command = strdup(
 636                     additional->force_command)) == NULL)
 637                         goto alloc_fail;
 638         }
 639         /* success */
 640         if (errstrp != NULL)
 641                 *errstrp = NULL;
 642         return ret;
 643
 644  alloc_fail:
 645         errstr = "memory allocation failed";
 646  fail:
 647         if (errstrp != NULL)
 648                 *errstrp = errstr;
 649         sshauthopt_free(ret);
 650         return NULL;
 651 }
 652
 653 /*
 654  * Copy options
 655  */
 656 struct sshauthopt *
 657 sshauthopt_copy(const struct sshauthopt *orig)
 658 {
 659         struct sshauthopt *ret;
 660
 661         if ((ret = sshauthopt_new()) == NULL)
 662                 return NULL;
 663
 664 #define OPTSCALAR(x) ret->x = orig->x
 665         OPTSCALAR(permit_port_forwarding_flag);
 666         OPTSCALAR(permit_agent_forwarding_flag);
 667         OPTSCALAR(permit_x11_forwarding_flag);
 668         OPTSCALAR(permit_pty_flag);
 669         OPTSCALAR(permit_user_rc);
 670         OPTSCALAR(restricted);
 671         OPTSCALAR(cert_authority);
 672         OPTSCALAR(force_tun_device);
 673         OPTSCALAR(valid_before);
 674         OPTSCALAR(no_require_user_presence);
 675         OPTSCALAR(require_verify);
 676 #undef OPTSCALAR
 677 #define OPTSTRING(x) \
 678         do { \
 679                 if (orig->x != NULL && (ret->x = strdup(orig->x)) == NULL) { \
 680                         sshauthopt_free(ret); \
 681                         return NULL; \
 682                 } \
 683         } while (0)
 684         OPTSTRING(cert_principals);
 685         OPTSTRING(force_command);
 686         OPTSTRING(required_from_host_cert);
 687         OPTSTRING(required_from_host_keys);
 688 #undef OPTSTRING
 689
 690         if (dup_strings(&ret->env, &ret->nenv, orig->env, orig->nenv) != 0 ||
 691             dup_strings(&ret->permitopen, &ret->npermitopen,
 692             orig->permitopen, orig->npermitopen) != 0 ||
 693             dup_strings(&ret->permitlisten, &ret->npermitlisten,
 694             orig->permitlisten, orig->npermitlisten) != 0) {
 695                 sshauthopt_free(ret);
 696                 return NULL;
 697         }
 698         return ret;
 699 }
 700
 701 static int
 702 serialise_array(struct sshbuf *m, char **a, size_t n)
 703 {
 704         struct sshbuf *b;
 705         size_t i;
 706         int r;
 707
 708         if (n > INT_MAX)
 709                 return SSH_ERR_INTERNAL_ERROR;
 710
 711         if ((b = sshbuf_new()) == NULL) {
 712                 return SSH_ERR_ALLOC_FAIL;
 713         }
 714         for (i = 0; i < n; i++) {
 715                 if ((r = sshbuf_put_cstring(b, a[i])) != 0) {
 716                         sshbuf_free(b);
 717                         return r;
 718                 }
 719         }
 720         if ((r = sshbuf_put_u32(m, n)) != 0 ||
 721             (r = sshbuf_put_stringb(m, b)) != 0) {
 722                 sshbuf_free(b);
 723                 return r;
 724         }
 725         /* success */
 726         return 0;
 727 }
 728
 729 static int
 730 deserialise_array(struct sshbuf *m, char ***ap, size_t *np)
 731 {
 732         char **a = NULL;
 733         size_t i, n = 0;
 734         struct sshbuf *b = NULL;
 735         u_int tmp;
 736         int r = SSH_ERR_INTERNAL_ERROR;
 737
 738         if ((r = sshbuf_get_u32(m, &tmp)) != 0 ||
 739             (r = sshbuf_froms(m, &b)) != 0)
 740                 goto out;
 741         if (tmp > INT_MAX) {
 742                 r = SSH_ERR_INVALID_FORMAT;
 743                 goto out;
 744         }
 745         n = tmp;
 746         if (n > 0 && (a = calloc(n, sizeof(*a))) == NULL) {
 747                 r = SSH_ERR_ALLOC_FAIL;
 748                 goto out;
 749         }
 750         for (i = 0; i < n; i++) {
 751                 if ((r = sshbuf_get_cstring(b, &a[i], NULL)) != 0)
 752                         goto out;
 753         }
 754         /* success */
 755         r = 0;
 756         *ap = a;
 757         a = NULL;
 758         *np = n;
 759         n = 0;
 760  out:
 761         if (a != NULL) {
 762                 for (i = 0; i < n; i++)
 763                         free(a[i]);
 764                 free(a);
 765         }
 766         sshbuf_free(b);
 767         return r;
 768 }
 769
 770 static int
 771 serialise_nullable_string(struct sshbuf *m, const char *s)
 772 {
 773         int r;
 774
 775         if ((r = sshbuf_put_u8(m, s == NULL)) != 0 ||
 776             (r = sshbuf_put_cstring(m, s)) != 0)
 777                 return r;
 778         return 0;
 779 }
 780
 781 static int
 782 deserialise_nullable_string(struct sshbuf *m, char **sp)
 783 {
 784         int r;
 785         u_char flag;
 786
 787         *sp = NULL;
 788         if ((r = sshbuf_get_u8(m, &flag)) != 0 ||
 789             (r = sshbuf_get_cstring(m, flag ? NULL : sp, NULL)) != 0)
 790                 return r;
 791         return 0;
 792 }
 793
 794 int
 795 sshauthopt_serialise(const struct sshauthopt *opts, struct sshbuf *m,
 796     int untrusted)
 797 {
 798         int r = SSH_ERR_INTERNAL_ERROR;
 799
 800         /* Flag options */
 801         if ((r = sshbuf_put_u8(m, opts->permit_port_forwarding_flag)) != 0 ||
 802             (r = sshbuf_put_u8(m, opts->permit_agent_forwarding_flag)) != 0 ||
 803             (r = sshbuf_put_u8(m, opts->permit_x11_forwarding_flag)) != 0 ||
 804             (r = sshbuf_put_u8(m, opts->permit_pty_flag)) != 0 ||
 805             (r = sshbuf_put_u8(m, opts->permit_user_rc)) != 0 ||
 806             (r = sshbuf_put_u8(m, opts->restricted)) != 0 ||
 807             (r = sshbuf_put_u8(m, opts->cert_authority)) != 0 ||
 808             (r = sshbuf_put_u8(m, opts->no_require_user_presence)) != 0 ||
 809             (r = sshbuf_put_u8(m, opts->require_verify)) != 0)
 810                 return r;
 811
 812         /* Simple integer options */
 813         if ((r = sshbuf_put_u64(m, opts->valid_before)) != 0)
 814                 return r;
 815
 816         /* tunnel number can be negative to indicate "unset" */
 817         if ((r = sshbuf_put_u8(m, opts->force_tun_device == -1)) != 0 ||
 818             (r = sshbuf_put_u32(m, (opts->force_tun_device < 0) ?
 819             0 : (u_int)opts->force_tun_device)) != 0)
 820                 return r;
 821
 822         /* String options; these may be NULL */
 823         if ((r = serialise_nullable_string(m,
 824             untrusted ? "yes" : opts->cert_principals)) != 0 ||
 825             (r = serialise_nullable_string(m,
 826             untrusted ? "true" : opts->force_command)) != 0 ||
 827             (r = serialise_nullable_string(m,
 828             untrusted ? NULL : opts->required_from_host_cert)) != 0 ||
 829             (r = serialise_nullable_string(m,
 830             untrusted ? NULL : opts->required_from_host_keys)) != 0)
 831                 return r;
 832
 833         /* Array options */
 834         if ((r = serialise_array(m, opts->env,
 835             untrusted ? 0 : opts->nenv)) != 0 ||
 836             (r = serialise_array(m, opts->permitopen,
 837             untrusted ? 0 : opts->npermitopen)) != 0 ||
 838             (r = serialise_array(m, opts->permitlisten,
 839             untrusted ? 0 : opts->npermitlisten)) != 0)
 840                 return r;
 841
 842         /* success */
 843         return 0;
 844 }
 845
 846 int
 847 sshauthopt_deserialise(struct sshbuf *m, struct sshauthopt **optsp)
 848 {
 849         struct sshauthopt *opts = NULL;
 850         int r = SSH_ERR_INTERNAL_ERROR;
 851         u_char f;
 852         u_int tmp;
 853
 854         if ((opts = calloc(1, sizeof(*opts))) == NULL)
 855                 return SSH_ERR_ALLOC_FAIL;
 856
 857         /* Flag options */
 858 #define OPT_FLAG(x) \
 859         do { \
 860                 if ((r = sshbuf_get_u8(m, &f)) != 0) \
 861                         goto out; \
 862                 opts->x = f; \
 863         } while (0)
 864         OPT_FLAG(permit_port_forwarding_flag);
 865         OPT_FLAG(permit_agent_forwarding_flag);
 866         OPT_FLAG(permit_x11_forwarding_flag);
 867         OPT_FLAG(permit_pty_flag);
 868         OPT_FLAG(permit_user_rc);
 869         OPT_FLAG(restricted);
 870         OPT_FLAG(cert_authority);
 871         OPT_FLAG(no_require_user_presence);
 872         OPT_FLAG(require_verify);
 873 #undef OPT_FLAG
 874
 875         /* Simple integer options */
 876         if ((r = sshbuf_get_u64(m, &opts->valid_before)) != 0)
 877                 goto out;
 878
 879         /* tunnel number can be negative to indicate "unset" */
 880         if ((r = sshbuf_get_u8(m, &f)) != 0 ||
 881             (r = sshbuf_get_u32(m, &tmp)) != 0)
 882                 goto out;
 883         opts->force_tun_device = f ? -1 : (int)tmp;
 884
 885         /* String options may be NULL */
 886         if ((r = deserialise_nullable_string(m, &opts->cert_principals)) != 0 ||
 887             (r = deserialise_nullable_string(m, &opts->force_command)) != 0 ||
 888             (r = deserialise_nullable_string(m,
 889             &opts->required_from_host_cert)) != 0 ||
 890             (r = deserialise_nullable_string(m,
 891             &opts->required_from_host_keys)) != 0)
 892                 goto out;
 893
 894         /* Array options */
 895         if ((r = deserialise_array(m, &opts->env, &opts->nenv)) != 0 ||
 896             (r = deserialise_array(m,
 897             &opts->permitopen, &opts->npermitopen)) != 0 ||
 898             (r = deserialise_array(m,
 899             &opts->permitlisten, &opts->npermitlisten)) != 0)
 900                 goto out;
 901
 902         /* success */
 903         r = 0;
 904         *optsp = opts;
 905         opts = NULL;
 906  out:
 907         sshauthopt_free(opts);
 908         return r;
 909 }