crypto/openssh/auth-options.c

   1 /* $OpenBSD: auth-options.c,v 1.101 2023/07/14 07:44:21 dtucker Exp $ */
   2 /*
   3  * Copyright (c) 2018 Damien Miller <djm@mindrot.org>
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 #include "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 #ifdef HAVE_STDINT_H
  28 # include <stdint.h>
  29 #endif
  30 #include <stdarg.h>
  31 #include <ctype.h>
  32 #include <limits.h>
  33
  34 #include "openbsd-compat/sys-queue.h"
  35
  36 #include "xmalloc.h"
  37 #include "ssherr.h"
  38 #include "log.h"
  39 #include "sshbuf.h"
  40 #include "misc.h"
  41 #include "sshkey.h"
  42 #include "match.h"
  43 #include "ssh2.h"
  44 #include "auth-options.h"
  45
  46 static int
  47 dup_strings(char ***dstp, size_t *ndstp, char **src, size_t nsrc)
  48 {
  49         char **dst;
  50         size_t i, j;
  51
  52         *dstp = NULL;
  53         *ndstp = 0;
  54
  55         if (nsrc == 0)
  56                 return 0;
  57         if (nsrc >= SIZE_MAX / sizeof(*src) ||
  58             (dst = calloc(nsrc, sizeof(*src))) == NULL)
  59                 return -1;
  60         for (i = 0; i < nsrc; i++) {
  61                 if ((dst[i] = strdup(src[i])) == NULL) {
  62                         for (j = 0; j < i; j++)
  63                                 free(dst[j]);
  64                         free(dst);
  65                         return -1;
  66                 }
  67         }
  68         /* success */
  69         *dstp = dst;
  70         *ndstp = nsrc;
  71         return 0;
  72 }
  73
  74 #define OPTIONS_CRITICAL        1
  75 #define OPTIONS_EXTENSIONS      2
  76 static int
  77 cert_option_list(struct sshauthopt *opts, struct sshbuf *oblob,
  78     u_int which, int crit)
  79 {
  80         char *command, *allowed;
  81         char *name = NULL;
  82         struct sshbuf *c = NULL, *data = NULL;
  83         int r, ret = -1, found;
  84
  85         if ((c = sshbuf_fromb(oblob)) == NULL) {
  86                 error_f("sshbuf_fromb failed");
  87                 goto out;
  88         }
  89
  90         while (sshbuf_len(c) > 0) {
  91                 sshbuf_free(data);
  92                 data = NULL;
  93                 if ((r = sshbuf_get_cstring(c, &name, NULL)) != 0 ||
  94                     (r = sshbuf_froms(c, &data)) != 0) {
  95                         error_r(r, "Unable to parse certificate options");
  96                         goto out;
  97                 }
  98                 debug3("found certificate option \"%.100s\" len %zu",
  99                     name, sshbuf_len(data));
 100                 found = 0;
 101                 if ((which & OPTIONS_EXTENSIONS) != 0) {
 102                         if (strcmp(name, "no-touch-required") == 0) {
 103                                 opts->no_require_user_presence = 1;
 104                                 found = 1;
 105                         } else if (strcmp(name, "permit-X11-forwarding") == 0) {
 106                                 opts->permit_x11_forwarding_flag = 1;
 107                                 found = 1;
 108                         } else if (strcmp(name,
 109                             "permit-agent-forwarding") == 0) {
 110                                 opts->permit_agent_forwarding_flag = 1;
 111                                 found = 1;
 112                         } else if (strcmp(name,
 113                             "permit-port-forwarding") == 0) {
 114                                 opts->permit_port_forwarding_flag = 1;
 115                                 found = 1;
 116                         } else if (strcmp(name, "permit-pty") == 0) {
 117                                 opts->permit_pty_flag = 1;
 118                                 found = 1;
 119                         } else if (strcmp(name, "permit-user-rc") == 0) {
 120                                 opts->permit_user_rc = 1;
 121                                 found = 1;
 122                         }
 123                 }
 124                 if (!found && (which & OPTIONS_CRITICAL) != 0) {
 125                         if (strcmp(name, "verify-required") == 0) {
 126                                 opts->require_verify = 1;
 127                                 found = 1;
 128                         } else if (strcmp(name, "force-command") == 0) {
 129                                 if ((r = sshbuf_get_cstring(data, &command,
 130                                     NULL)) != 0) {
 131                                         error_r(r, "Unable to parse \"%s\" "
 132                                             "section", name);
 133                                         goto out;
 134                                 }
 135                                 if (opts->force_command != NULL) {
 136                                         error("Certificate has multiple "
 137                                             "force-command options");
 138                                         free(command);
 139                                         goto out;
 140                                 }
 141                                 opts->force_command = command;
 142                                 found = 1;
 143                         } else if (strcmp(name, "source-address") == 0) {
 144                                 if ((r = sshbuf_get_cstring(data, &allowed,
 145                                     NULL)) != 0) {
 146                                         error_r(r, "Unable to parse \"%s\" "
 147                                             "section", name);
 148                                         goto out;
 149                                 }
 150                                 if (opts->required_from_host_cert != NULL) {
 151                                         error("Certificate has multiple "
 152                                             "source-address options");
 153                                         free(allowed);
 154                                         goto out;
 155                                 }
 156                                 /* Check syntax */
 157                                 if (addr_match_cidr_list(NULL, allowed) == -1) {
 158                                         error("Certificate source-address "
 159                                             "contents invalid");
 160                                         goto out;
 161                                 }
 162                                 opts->required_from_host_cert = allowed;
 163                                 found = 1;
 164                         }
 165                 }
 166
 167                 if (!found) {
 168                         if (crit) {
 169                                 error("Certificate critical option \"%s\" "
 170                                     "is not supported", name);
 171                                 goto out;
 172                         } else {
 173                                 logit("Certificate extension \"%s\" "
 174                                     "is not supported", name);
 175                         }
 176                 } else if (sshbuf_len(data) != 0) {
 177                         error("Certificate option \"%s\" corrupt "
 178                             "(extra data)", name);
 179                         goto out;
 180                 }
 181                 free(name);
 182                 name = NULL;
 183         }
 184         /* successfully parsed all options */
 185         ret = 0;
 186
 187  out:
 188         free(name);
 189         sshbuf_free(data);
 190         sshbuf_free(c);
 191         return ret;
 192 }
 193
 194 struct sshauthopt *
 195 sshauthopt_new(void)
 196 {
 197         struct sshauthopt *ret;
 198
 199         if ((ret = calloc(1, sizeof(*ret))) == NULL)
 200                 return NULL;
 201         ret->force_tun_device = -1;
 202         return ret;
 203 }
 204
 205 void
 206 sshauthopt_free(struct sshauthopt *opts)
 207 {
 208         size_t i;
 209
 210         if (opts == NULL)
 211                 return;
 212
 213         free(opts->cert_principals);
 214         free(opts->force_command);
 215         free(opts->required_from_host_cert);
 216         free(opts->required_from_host_keys);
 217
 218         for (i = 0; i < opts->nenv; i++)
 219                 free(opts->env[i]);
 220         free(opts->env);
 221
 222         for (i = 0; i < opts->npermitopen; i++)
 223                 free(opts->permitopen[i]);
 224         free(opts->permitopen);
 225
 226         for (i = 0; i < opts->npermitlisten; i++)
 227                 free(opts->permitlisten[i]);
 228         free(opts->permitlisten);
 229
 230         freezero(opts, sizeof(*opts));
 231 }
 232
 233 struct sshauthopt *
 234 sshauthopt_new_with_keys_defaults(void)
 235 {
 236         struct sshauthopt *ret = NULL;
 237
 238         if ((ret = sshauthopt_new()) == NULL)
 239                 return NULL;
 240
 241         /* Defaults for authorized_keys flags */
 242         ret->permit_port_forwarding_flag = 1;
 243         ret->permit_agent_forwarding_flag = 1;
 244         ret->permit_x11_forwarding_flag = 1;
 245         ret->permit_pty_flag = 1;
 246         ret->permit_user_rc = 1;
 247         return ret;
 248 }
 249
 250 /*
 251  * Parse and record a permitopen/permitlisten directive.
 252  * Return 0 on success. Return -1 on failure and sets *errstrp to error reason.
 253  */
 254 static int
 255 handle_permit(const char **optsp, int allow_bare_port,
 256     char ***permitsp, size_t *npermitsp, const char **errstrp)
 257 {
 258         char *opt, *tmp, *cp, *host, **permits = *permitsp;
 259         size_t npermits = *npermitsp;
 260         const char *errstr = "unknown error";
 261
 262         if (npermits > SSH_AUTHOPT_PERMIT_MAX) {
 263                 *errstrp = "too many permission directives";
 264                 return -1;
 265         }
 266         if ((opt = opt_dequote(optsp, &errstr)) == NULL) {
 267                 return -1;
 268         }
 269         if (allow_bare_port && strchr(opt, ':') == NULL) {
 270                 /*
 271                  * Allow a bare port number in permitlisten to indicate a
 272                  * listen_host wildcard.
 273                  */
 274                 if (asprintf(&tmp, "*:%s", opt) == -1) {
 275                         free(opt);
 276                         *errstrp = "memory allocation failed";
 277                         return -1;
 278                 }
 279                 free(opt);
 280                 opt = tmp;
 281         }
 282         if ((tmp = strdup(opt)) == NULL) {
 283                 free(opt);
 284                 *errstrp = "memory allocation failed";
 285                 return -1;
 286         }
 287         cp = tmp;
 288         /* validate syntax before recording it. */
 289         host = hpdelim2(&cp, NULL);
 290         if (host == NULL || strlen(host) >= NI_MAXHOST) {
 291                 free(tmp);
 292                 free(opt);
 293                 *errstrp = "invalid permission hostname";
 294                 return -1;
 295         }
 296         /*
 297          * don't want to use permitopen_port to avoid
 298          * dependency on channels.[ch] here.
 299          */
 300         if (cp == NULL ||
 301             (strcmp(cp, "*") != 0 && a2port(cp) <= 0)) {
 302                 free(tmp);
 303                 free(opt);
 304                 *errstrp = "invalid permission port";
 305                 return -1;
 306         }
 307         /* XXX - add streamlocal support */
 308         free(tmp);
 309         /* Record it */
 310         if ((permits = recallocarray(permits, npermits, npermits + 1,
 311             sizeof(*permits))) == NULL) {
 312                 free(opt);
 313                 /* NB. don't update *permitsp if alloc fails */
 314                 *errstrp = "memory allocation failed";
 315                 return -1;
 316         }
 317         permits[npermits++] = opt;
 318         *permitsp = permits;
 319         *npermitsp = npermits;
 320         return 0;
 321 }
 322
 323 struct sshauthopt *
 324 sshauthopt_parse(const char *opts, const char **errstrp)
 325 {
 326         char **oarray, *opt, *cp, *tmp;
 327         int r;
 328         struct sshauthopt *ret = NULL;
 329         const char *errstr = "unknown error";
 330         uint64_t valid_before;
 331         size_t i, l;
 332
 333         if (errstrp != NULL)
 334                 *errstrp = NULL;
 335         if ((ret = sshauthopt_new_with_keys_defaults()) == NULL)
 336                 goto alloc_fail;
 337
 338         if (opts == NULL)
 339                 return ret;
 340
 341         while (*opts && *opts != ' ' && *opts != '\t') {
 342                 /* flag options */
 343                 if ((r = opt_flag("restrict", 0, &opts)) != -1) {
 344                         ret->restricted = 1;
 345                         ret->permit_port_forwarding_flag = 0;
 346                         ret->permit_agent_forwarding_flag = 0;
 347                         ret->permit_x11_forwarding_flag = 0;
 348                         ret->permit_pty_flag = 0;
 349                         ret->permit_user_rc = 0;
 350                 } else if ((r = opt_flag("cert-authority", 0, &opts)) != -1) {
 351                         ret->cert_authority = r;
 352                 } else if ((r = opt_flag("port-forwarding", 1, &opts)) != -1) {
 353                         ret->permit_port_forwarding_flag = r == 1;
 354                 } else if ((r = opt_flag("agent-forwarding", 1, &opts)) != -1) {
 355                         ret->permit_agent_forwarding_flag = r == 1;
 356                 } else if ((r = opt_flag("x11-forwarding", 1, &opts)) != -1) {
 357                         ret->permit_x11_forwarding_flag = r == 1;
 358                 } else if ((r = opt_flag("touch-required", 1, &opts)) != -1) {
 359                         ret->no_require_user_presence = r != 1; /* NB. flip */
 360                 } else if ((r = opt_flag("verify-required", 1, &opts)) != -1) {
 361                         ret->require_verify = r == 1;
 362                 } else if ((r = opt_flag("pty", 1, &opts)) != -1) {
 363                         ret->permit_pty_flag = r == 1;
 364                 } else if ((r = opt_flag("user-rc", 1, &opts)) != -1) {
 365                         ret->permit_user_rc = r == 1;
 366                 } else if (opt_match(&opts, "command")) {
 367                         if (ret->force_command != NULL) {
 368                                 errstr = "multiple \"command\" clauses";
 369                                 goto fail;
 370                         }
 371                         ret->force_command = opt_dequote(&opts, &errstr);
 372                         if (ret->force_command == NULL)
 373                                 goto fail;
 374                 } else if (opt_match(&opts, "principals")) {
 375                         if (ret->cert_principals != NULL) {
 376                                 errstr = "multiple \"principals\" clauses";
 377                                 goto fail;
 378                         }
 379                         ret->cert_principals = opt_dequote(&opts, &errstr);
 380                         if (ret->cert_principals == NULL)
 381                                 goto fail;
 382                 } else if (opt_match(&opts, "from")) {
 383                         if (ret->required_from_host_keys != NULL) {
 384                                 errstr = "multiple \"from\" clauses";
 385                                 goto fail;
 386                         }
 387                         ret->required_from_host_keys = opt_dequote(&opts,
 388                             &errstr);
 389                         if (ret->required_from_host_keys == NULL)
 390                                 goto fail;
 391                 } else if (opt_match(&opts, "expiry-time")) {
 392                         if ((opt = opt_dequote(&opts, &errstr)) == NULL)
 393                                 goto fail;
 394                         if (parse_absolute_time(opt, &valid_before) != 0 ||
 395                             valid_before == 0) {
 396                                 free(opt);
 397                                 errstr = "invalid expires time";
 398                                 goto fail;
 399                         }
 400                         free(opt);
 401                         if (ret->valid_before == 0 ||
 402                             valid_before < ret->valid_before)
 403                                 ret->valid_before = valid_before;
 404                 } else if (opt_match(&opts, "environment")) {
 405                         if (ret->nenv > SSH_AUTHOPT_ENV_MAX) {
 406                                 errstr = "too many environment strings";
 407                                 goto fail;
 408                         }
 409                         if ((opt = opt_dequote(&opts, &errstr)) == NULL)
 410                                 goto fail;
 411                         /* env name must be alphanumeric and followed by '=' */
 412                         if ((tmp = strchr(opt, '=')) == NULL) {
 413                                 free(opt);
 414                                 errstr = "invalid environment string";
 415                                 goto fail;
 416                         }
 417                         if ((cp = strdup(opt)) == NULL) {
 418                                 free(opt);
 419                                 goto alloc_fail;
 420                         }
 421                         l = (size_t)(tmp - opt);
 422                         cp[l] = '\0'; /* truncate at '=' */
 423                         if (!valid_env_name(cp)) {
 424                                 free(cp);
 425                                 free(opt);
 426                                 errstr = "invalid environment string";
 427                                 goto fail;
 428                         }
 429                         /* Check for duplicates; XXX O(n*log(n)) */
 430                         for (i = 0; i < ret->nenv; i++) {
 431                                 if (strncmp(ret->env[i], cp, l) == 0 &&
 432                                     ret->env[i][l] == '=')
 433                                         break;
 434                         }
 435                         free(cp);
 436                         /* First match wins */
 437                         if (i >= ret->nenv) {
 438                                 /* Append it. */
 439                                 oarray = ret->env;
 440                                 if ((ret->env = recallocarray(ret->env,
 441                                     ret->nenv, ret->nenv + 1,
 442                                     sizeof(*ret->env))) == NULL) {
 443                                         free(opt);
 444                                         /* put it back for cleanup */
 445                                         ret->env = oarray;
 446                                         goto alloc_fail;
 447                                 }
 448                                 ret->env[ret->nenv++] = opt;
 449                                 opt = NULL; /* transferred */
 450                         }
 451                         free(opt);
 452                 } else if (opt_match(&opts, "permitopen")) {
 453                         if (handle_permit(&opts, 0, &ret->permitopen,
 454                             &ret->npermitopen, &errstr) != 0)
 455                                 goto fail;
 456                 } else if (opt_match(&opts, "permitlisten")) {
 457                         if (handle_permit(&opts, 1, &ret->permitlisten,
 458                             &ret->npermitlisten, &errstr) != 0)
 459                                 goto fail;
 460                 } else if (opt_match(&opts, "tunnel")) {
 461                         if ((opt = opt_dequote(&opts, &errstr)) == NULL)
 462                                 goto fail;
 463                         ret->force_tun_device = a2tun(opt, NULL);
 464                         free(opt);
 465                         if (ret->force_tun_device == SSH_TUNID_ERR) {
 466                                 errstr = "invalid tun device";
 467                                 goto fail;
 468                         }
 469                 }
 470                 /*
 471                  * Skip the comma, and move to the next option
 472                  * (or break out if there are no more).
 473                  */
 474                 if (*opts == '\0' || *opts == ' ' || *opts == '\t')
 475                         break;          /* End of options. */
 476                 /* Anything other than a comma is an unknown option */
 477                 if (*opts != ',') {
 478                         errstr = "unknown key option";
 479                         goto fail;
 480                 }
 481                 opts++;
 482                 if (*opts == '\0') {
 483                         errstr = "unexpected end-of-options";
 484                         goto fail;
 485                 }
 486         }
 487
 488         /* success */
 489         if (errstrp != NULL)
 490                 *errstrp = NULL;
 491         return ret;
 492
 493 alloc_fail:
 494         errstr = "memory allocation failed";
 495 fail:
 496         sshauthopt_free(ret);
 497         if (errstrp != NULL)
 498                 *errstrp = errstr;
 499         return NULL;
 500 }
 501
 502 struct sshauthopt *
 503 sshauthopt_from_cert(struct sshkey *k)
 504 {
 505         struct sshauthopt *ret;
 506
 507         if (k == NULL || !sshkey_type_is_cert(k->type) || k->cert == NULL ||
 508             k->cert->type != SSH2_CERT_TYPE_USER)
 509                 return NULL;
 510
 511         if ((ret = sshauthopt_new()) == NULL)
 512                 return NULL;
 513
 514         /* Handle options and critical extensions separately */
 515         if (cert_option_list(ret, k->cert->critical,
 516             OPTIONS_CRITICAL, 1) == -1) {
 517                 sshauthopt_free(ret);
 518                 return NULL;
 519         }
 520         if (cert_option_list(ret, k->cert->extensions,
 521             OPTIONS_EXTENSIONS, 0) == -1) {
 522                 sshauthopt_free(ret);
 523                 return NULL;
 524         }
 525         /* success */
 526         return ret;
 527 }
 528
 529 /*
 530  * Merges "additional" options to "primary" and returns the result.
 531  * NB. Some options from primary have primacy.
 532  */
 533 struct sshauthopt *
 534 sshauthopt_merge(const struct sshauthopt *primary,
 535     const struct sshauthopt *additional, const char **errstrp)
 536 {
 537         struct sshauthopt *ret;
 538         const char *errstr = "internal error";
 539         const char *tmp;
 540
 541         if (errstrp != NULL)
 542                 *errstrp = NULL;
 543
 544         if ((ret = sshauthopt_new()) == NULL)
 545                 goto alloc_fail;
 546
 547         /* cert_authority and cert_principals are cleared in result */
 548
 549         /* Prefer access lists from primary. */
 550         /* XXX err is both set and mismatch? */
 551         tmp = primary->required_from_host_cert;
 552         if (tmp == NULL)
 553                 tmp = additional->required_from_host_cert;
 554         if (tmp != NULL && (ret->required_from_host_cert = strdup(tmp)) == NULL)
 555                 goto alloc_fail;
 556         tmp = primary->required_from_host_keys;
 557         if (tmp == NULL)
 558                 tmp = additional->required_from_host_keys;
 559         if (tmp != NULL && (ret->required_from_host_keys = strdup(tmp)) == NULL)
 560                 goto alloc_fail;
 561
 562         /*
 563          * force_tun_device, permitopen/permitlisten and environment all
 564          * prefer the primary.
 565          */
 566         ret->force_tun_device = primary->force_tun_device;
 567         if (ret->force_tun_device == -1)
 568                 ret->force_tun_device = additional->force_tun_device;
 569         if (primary->nenv > 0) {
 570                 if (dup_strings(&ret->env, &ret->nenv,
 571                     primary->env, primary->nenv) != 0)
 572                         goto alloc_fail;
 573         } else if (additional->nenv) {
 574                 if (dup_strings(&ret->env, &ret->nenv,
 575                     additional->env, additional->nenv) != 0)
 576                         goto alloc_fail;
 577         }
 578         if (primary->npermitopen > 0) {
 579                 if (dup_strings(&ret->permitopen, &ret->npermitopen,
 580                     primary->permitopen, primary->npermitopen) != 0)
 581                         goto alloc_fail;
 582         } else if (additional->npermitopen > 0) {
 583                 if (dup_strings(&ret->permitopen, &ret->npermitopen,
 584                     additional->permitopen, additional->npermitopen) != 0)
 585                         goto alloc_fail;
 586         }
 587
 588         if (primary->npermitlisten > 0) {
 589                 if (dup_strings(&ret->permitlisten, &ret->npermitlisten,
 590                     primary->permitlisten, primary->npermitlisten) != 0)
 591                         goto alloc_fail;
 592         } else if (additional->npermitlisten > 0) {
 593                 if (dup_strings(&ret->permitlisten, &ret->npermitlisten,
 594                     additional->permitlisten, additional->npermitlisten) != 0)
 595                         goto alloc_fail;
 596         }
 597
 598 #define OPTFLAG_AND(x) ret->x = (primary->x == 1) && (additional->x == 1)
 599 #define OPTFLAG_OR(x) ret->x = (primary->x == 1) || (additional->x == 1)
 600         /* Permissive flags are logical-AND (i.e. must be set in both) */
 601         OPTFLAG_AND(permit_port_forwarding_flag);
 602         OPTFLAG_AND(permit_agent_forwarding_flag);
 603         OPTFLAG_AND(permit_x11_forwarding_flag);
 604         OPTFLAG_AND(permit_pty_flag);
 605         OPTFLAG_AND(permit_user_rc);
 606         OPTFLAG_AND(no_require_user_presence);
 607         /* Restrictive flags are logical-OR (i.e. must be set in either) */
 608         OPTFLAG_OR(require_verify);
 609 #undef OPTFLAG_AND
 610
 611         /* Earliest expiry time should win */
 612         if (primary->valid_before != 0)
 613                 ret->valid_before = primary->valid_before;
 614         if (additional->valid_before != 0 &&
 615             additional->valid_before < ret->valid_before)
 616                 ret->valid_before = additional->valid_before;
 617
 618         /*
 619          * When both multiple forced-command are specified, only
 620          * proceed if they are identical, otherwise fail.
 621          */
 622         if (primary->force_command != NULL &&
 623             additional->force_command != NULL) {
 624                 if (strcmp(primary->force_command,
 625                     additional->force_command) == 0) {
 626                         /* ok */
 627                         ret->force_command = strdup(primary->force_command);
 628                         if (ret->force_command == NULL)
 629                                 goto alloc_fail;
 630                 } else {
 631                         errstr = "forced command options do not match";
 632                         goto fail;
 633                 }
 634         } else if (primary->force_command != NULL) {
 635                 if ((ret->force_command = strdup(
 636                     primary->force_command)) == NULL)
 637                         goto alloc_fail;
 638         } else if (additional->force_command != NULL) {
 639                 if ((ret->force_command = strdup(
 640                     additional->force_command)) == NULL)
 641                         goto alloc_fail;
 642         }
 643         /* success */
 644         if (errstrp != NULL)
 645                 *errstrp = NULL;
 646         return ret;
 647
 648  alloc_fail:
 649         errstr = "memory allocation failed";
 650  fail:
 651         if (errstrp != NULL)
 652                 *errstrp = errstr;
 653         sshauthopt_free(ret);
 654         return NULL;
 655 }
 656
 657 /*
 658  * Copy options
 659  */
 660 struct sshauthopt *
 661 sshauthopt_copy(const struct sshauthopt *orig)
 662 {
 663         struct sshauthopt *ret;
 664
 665         if ((ret = sshauthopt_new()) == NULL)
 666                 return NULL;
 667
 668 #define OPTSCALAR(x) ret->x = orig->x
 669         OPTSCALAR(permit_port_forwarding_flag);
 670         OPTSCALAR(permit_agent_forwarding_flag);
 671         OPTSCALAR(permit_x11_forwarding_flag);
 672         OPTSCALAR(permit_pty_flag);
 673         OPTSCALAR(permit_user_rc);
 674         OPTSCALAR(restricted);
 675         OPTSCALAR(cert_authority);
 676         OPTSCALAR(force_tun_device);
 677         OPTSCALAR(valid_before);
 678         OPTSCALAR(no_require_user_presence);
 679         OPTSCALAR(require_verify);
 680 #undef OPTSCALAR
 681 #define OPTSTRING(x) \
 682         do { \
 683                 if (orig->x != NULL && (ret->x = strdup(orig->x)) == NULL) { \
 684                         sshauthopt_free(ret); \
 685                         return NULL; \
 686                 } \
 687         } while (0)
 688         OPTSTRING(cert_principals);
 689         OPTSTRING(force_command);
 690         OPTSTRING(required_from_host_cert);
 691         OPTSTRING(required_from_host_keys);
 692 #undef OPTSTRING
 693
 694         if (dup_strings(&ret->env, &ret->nenv, orig->env, orig->nenv) != 0 ||
 695             dup_strings(&ret->permitopen, &ret->npermitopen,
 696             orig->permitopen, orig->npermitopen) != 0 ||
 697             dup_strings(&ret->permitlisten, &ret->npermitlisten,
 698             orig->permitlisten, orig->npermitlisten) != 0) {
 699                 sshauthopt_free(ret);
 700                 return NULL;
 701         }
 702         return ret;
 703 }
 704
 705 static int
 706 serialise_array(struct sshbuf *m, char **a, size_t n)
 707 {
 708         struct sshbuf *b;
 709         size_t i;
 710         int r = SSH_ERR_INTERNAL_ERROR;
 711
 712         if (n > INT_MAX)
 713                 return SSH_ERR_INTERNAL_ERROR;
 714
 715         if ((b = sshbuf_new()) == NULL) {
 716                 return SSH_ERR_ALLOC_FAIL;
 717         }
 718         for (i = 0; i < n; i++) {
 719                 if ((r = sshbuf_put_cstring(b, a[i])) != 0)
 720                         goto out;
 721         }
 722         if ((r = sshbuf_put_u32(m, n)) != 0 ||
 723             (r = sshbuf_put_stringb(m, b)) != 0)
 724                 goto out;
 725         /* success */
 726         r = 0;
 727  out:
 728         sshbuf_free(b);
 729         return r;
 730 }
 731
 732 static int
 733 deserialise_array(struct sshbuf *m, char ***ap, size_t *np)
 734 {
 735         char **a = NULL;
 736         size_t i, n = 0;
 737         struct sshbuf *b = NULL;
 738         u_int tmp;
 739         int r = SSH_ERR_INTERNAL_ERROR;
 740
 741         if ((r = sshbuf_get_u32(m, &tmp)) != 0 ||
 742             (r = sshbuf_froms(m, &b)) != 0)
 743                 goto out;
 744         if (tmp > INT_MAX) {
 745                 r = SSH_ERR_INVALID_FORMAT;
 746                 goto out;
 747         }
 748         n = tmp;
 749         if (n > 0 && (a = calloc(n, sizeof(*a))) == NULL) {
 750                 r = SSH_ERR_ALLOC_FAIL;
 751                 goto out;
 752         }
 753         for (i = 0; i < n; i++) {
 754                 if ((r = sshbuf_get_cstring(b, &a[i], NULL)) != 0)
 755                         goto out;
 756         }
 757         /* success */
 758         r = 0;
 759         *ap = a;
 760         a = NULL;
 761         *np = n;
 762         n = 0;
 763  out:
 764         if (a != NULL) {
 765                 for (i = 0; i < n; i++)
 766                         free(a[i]);
 767                 free(a);
 768         }
 769         sshbuf_free(b);
 770         return r;
 771 }
 772
 773 static int
 774 serialise_nullable_string(struct sshbuf *m, const char *s)
 775 {
 776         int r;
 777
 778         if ((r = sshbuf_put_u8(m, s == NULL)) != 0 ||
 779             (r = sshbuf_put_cstring(m, s)) != 0)
 780                 return r;
 781         return 0;
 782 }
 783
 784 static int
 785 deserialise_nullable_string(struct sshbuf *m, char **sp)
 786 {
 787         int r;
 788         u_char flag;
 789
 790         *sp = NULL;
 791         if ((r = sshbuf_get_u8(m, &flag)) != 0 ||
 792             (r = sshbuf_get_cstring(m, flag ? NULL : sp, NULL)) != 0)
 793                 return r;
 794         return 0;
 795 }
 796
 797 int
 798 sshauthopt_serialise(const struct sshauthopt *opts, struct sshbuf *m,
 799     int untrusted)
 800 {
 801         int r = SSH_ERR_INTERNAL_ERROR;
 802
 803         /* Flag options */
 804         if ((r = sshbuf_put_u8(m, opts->permit_port_forwarding_flag)) != 0 ||
 805             (r = sshbuf_put_u8(m, opts->permit_agent_forwarding_flag)) != 0 ||
 806             (r = sshbuf_put_u8(m, opts->permit_x11_forwarding_flag)) != 0 ||
 807             (r = sshbuf_put_u8(m, opts->permit_pty_flag)) != 0 ||
 808             (r = sshbuf_put_u8(m, opts->permit_user_rc)) != 0 ||
 809             (r = sshbuf_put_u8(m, opts->restricted)) != 0 ||
 810             (r = sshbuf_put_u8(m, opts->cert_authority)) != 0 ||
 811             (r = sshbuf_put_u8(m, opts->no_require_user_presence)) != 0 ||
 812             (r = sshbuf_put_u8(m, opts->require_verify)) != 0)
 813                 return r;
 814
 815         /* Simple integer options */
 816         if ((r = sshbuf_put_u64(m, opts->valid_before)) != 0)
 817                 return r;
 818
 819         /* tunnel number can be negative to indicate "unset" */
 820         if ((r = sshbuf_put_u8(m, opts->force_tun_device == -1)) != 0 ||
 821             (r = sshbuf_put_u32(m, (opts->force_tun_device < 0) ?
 822             0 : (u_int)opts->force_tun_device)) != 0)
 823                 return r;
 824
 825         /* String options; these may be NULL */
 826         if ((r = serialise_nullable_string(m,
 827             untrusted ? "yes" : opts->cert_principals)) != 0 ||
 828             (r = serialise_nullable_string(m,
 829             untrusted ? "true" : opts->force_command)) != 0 ||
 830             (r = serialise_nullable_string(m,
 831             untrusted ? NULL : opts->required_from_host_cert)) != 0 ||
 832             (r = serialise_nullable_string(m,
 833             untrusted ? NULL : opts->required_from_host_keys)) != 0)
 834                 return r;
 835
 836         /* Array options */
 837         if ((r = serialise_array(m, opts->env,
 838             untrusted ? 0 : opts->nenv)) != 0 ||
 839             (r = serialise_array(m, opts->permitopen,
 840             untrusted ? 0 : opts->npermitopen)) != 0 ||
 841             (r = serialise_array(m, opts->permitlisten,
 842             untrusted ? 0 : opts->npermitlisten)) != 0)
 843                 return r;
 844
 845         /* success */
 846         return 0;
 847 }
 848
 849 int
 850 sshauthopt_deserialise(struct sshbuf *m, struct sshauthopt **optsp)
 851 {
 852         struct sshauthopt *opts = NULL;
 853         int r = SSH_ERR_INTERNAL_ERROR;
 854         u_char f;
 855         u_int tmp;
 856
 857         if ((opts = calloc(1, sizeof(*opts))) == NULL)
 858                 return SSH_ERR_ALLOC_FAIL;
 859
 860         /* Flag options */
 861 #define OPT_FLAG(x) \
 862         do { \
 863                 if ((r = sshbuf_get_u8(m, &f)) != 0) \
 864                         goto out; \
 865                 opts->x = f; \
 866         } while (0)
 867         OPT_FLAG(permit_port_forwarding_flag);
 868         OPT_FLAG(permit_agent_forwarding_flag);
 869         OPT_FLAG(permit_x11_forwarding_flag);
 870         OPT_FLAG(permit_pty_flag);
 871         OPT_FLAG(permit_user_rc);
 872         OPT_FLAG(restricted);
 873         OPT_FLAG(cert_authority);
 874         OPT_FLAG(no_require_user_presence);
 875         OPT_FLAG(require_verify);
 876 #undef OPT_FLAG
 877
 878         /* Simple integer options */
 879         if ((r = sshbuf_get_u64(m, &opts->valid_before)) != 0)
 880                 goto out;
 881
 882         /* tunnel number can be negative to indicate "unset" */
 883         if ((r = sshbuf_get_u8(m, &f)) != 0 ||
 884             (r = sshbuf_get_u32(m, &tmp)) != 0)
 885                 goto out;
 886         opts->force_tun_device = f ? -1 : (int)tmp;
 887
 888         /* String options may be NULL */
 889         if ((r = deserialise_nullable_string(m, &opts->cert_principals)) != 0 ||
 890             (r = deserialise_nullable_string(m, &opts->force_command)) != 0 ||
 891             (r = deserialise_nullable_string(m,
 892             &opts->required_from_host_cert)) != 0 ||
 893             (r = deserialise_nullable_string(m,
 894             &opts->required_from_host_keys)) != 0)
 895                 goto out;
 896
 897         /* Array options */
 898         if ((r = deserialise_array(m, &opts->env, &opts->nenv)) != 0 ||
 899             (r = deserialise_array(m,
 900             &opts->permitopen, &opts->npermitopen)) != 0 ||
 901             (r = deserialise_array(m,
 902             &opts->permitlisten, &opts->npermitlisten)) != 0)
 903                 goto out;
 904
 905         /* success */
 906         r = 0;
 907         *optsp = opts;
 908         opts = NULL;
 909  out:
 910         sshauthopt_free(opts);
 911         return r;
 912 }