crypto/openssh/auth2-pubkey.c

   1 /* $OpenBSD: auth2-pubkey.c,v 1.38 2013/06/21 00:34:49 djm Exp $ */
   2 /*
   3  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "includes.h"
  27
  28 #include <sys/types.h>
  29 #include <sys/stat.h>
  30 #include <sys/wait.h>
  31
  32 #include <errno.h>
  33 #include <fcntl.h>
  34 #ifdef HAVE_PATHS_H
  35 # include <paths.h>
  36 #endif
  37 #include <pwd.h>
  38 #include <signal.h>
  39 #include <stdio.h>
  40 #include <stdarg.h>
  41 #include <string.h>
  42 #include <time.h>
  43 #include <unistd.h>
  44
  45 #include "xmalloc.h"
  46 #include "ssh.h"
  47 #include "ssh2.h"
  48 #include "packet.h"
  49 #include "buffer.h"
  50 #include "log.h"
  51 #include "servconf.h"
  52 #include "compat.h"
  53 #include "key.h"
  54 #include "hostfile.h"
  55 #include "auth.h"
  56 #include "pathnames.h"
  57 #include "uidswap.h"
  58 #include "auth-options.h"
  59 #include "canohost.h"
  60 #ifdef GSSAPI
  61 #include "ssh-gss.h"
  62 #endif
  63 #include "monitor_wrap.h"
  64 #include "misc.h"
  65 #include "authfile.h"
  66 #include "match.h"
  67
  68 /* import */
  69 extern ServerOptions options;
  70 extern u_char *session_id2;
  71 extern u_int session_id2_len;
  72
  73 static int
  74 userauth_pubkey(Authctxt *authctxt)
  75 {
  76         Buffer b;
  77         Key *key = NULL;
  78         char *pkalg, *userstyle;
  79         u_char *pkblob, *sig;
  80         u_int alen, blen, slen;
  81         int have_sig, pktype;
  82         int authenticated = 0;
  83
  84         if (!authctxt->valid) {
  85                 debug2("userauth_pubkey: disabled because of invalid user");
  86                 return 0;
  87         }
  88         have_sig = packet_get_char();
  89         if (datafellows & SSH_BUG_PKAUTH) {
  90                 debug2("userauth_pubkey: SSH_BUG_PKAUTH");
  91                 /* no explicit pkalg given */
  92                 pkblob = packet_get_string(&blen);
  93                 buffer_init(&b);
  94                 buffer_append(&b, pkblob, blen);
  95                 /* so we have to extract the pkalg from the pkblob */
  96                 pkalg = buffer_get_string(&b, &alen);
  97                 buffer_free(&b);
  98         } else {
  99                 pkalg = packet_get_string(&alen);
 100                 pkblob = packet_get_string(&blen);
 101         }
 102         pktype = key_type_from_name(pkalg);
 103         if (pktype == KEY_UNSPEC) {
 104                 /* this is perfectly legal */
 105                 logit("userauth_pubkey: unsupported public key algorithm: %s",
 106                     pkalg);
 107                 goto done;
 108         }
 109         key = key_from_blob(pkblob, blen);
 110         if (key == NULL) {
 111                 error("userauth_pubkey: cannot decode key: %s", pkalg);
 112                 goto done;
 113         }
 114         if (key->type != pktype) {
 115                 error("userauth_pubkey: type mismatch for decoded key "
 116                     "(received %d, expected %d)", key->type, pktype);
 117                 goto done;
 118         }
 119         if (have_sig) {
 120                 sig = packet_get_string(&slen);
 121                 packet_check_eom();
 122                 buffer_init(&b);
 123                 if (datafellows & SSH_OLD_SESSIONID) {
 124                         buffer_append(&b, session_id2, session_id2_len);
 125                 } else {
 126                         buffer_put_string(&b, session_id2, session_id2_len);
 127                 }
 128                 /* reconstruct packet */
 129                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
 130                 xasprintf(&userstyle, "%s%s%s", authctxt->user,
 131                     authctxt->style ? ":" : "",
 132                     authctxt->style ? authctxt->style : "");
 133                 buffer_put_cstring(&b, userstyle);
 134                 free(userstyle);
 135                 buffer_put_cstring(&b,
 136                     datafellows & SSH_BUG_PKSERVICE ?
 137                     "ssh-userauth" :
 138                     authctxt->service);
 139                 if (datafellows & SSH_BUG_PKAUTH) {
 140                         buffer_put_char(&b, have_sig);
 141                 } else {
 142                         buffer_put_cstring(&b, "publickey");
 143                         buffer_put_char(&b, have_sig);
 144                         buffer_put_cstring(&b, pkalg);
 145                 }
 146                 buffer_put_string(&b, pkblob, blen);
 147 #ifdef DEBUG_PK
 148                 buffer_dump(&b);
 149 #endif
 150                 pubkey_auth_info(authctxt, key, NULL);
 151
 152                 /* test for correct signature */
 153                 authenticated = 0;
 154                 if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
 155                     PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
 156                     buffer_len(&b))) == 1)
 157                         authenticated = 1;
 158                 buffer_free(&b);
 159                 free(sig);
 160         } else {
 161                 debug("test whether pkalg/pkblob are acceptable");
 162                 packet_check_eom();
 163
 164                 /* XXX fake reply and always send PK_OK ? */
 165                 /*
 166                  * XXX this allows testing whether a user is allowed
 167                  * to login: if you happen to have a valid pubkey this
 168                  * message is sent. the message is NEVER sent at all
 169                  * if a user is not allowed to login. is this an
 170                  * issue? -markus
 171                  */
 172                 if (PRIVSEP(user_key_allowed(authctxt->pw, key))) {
 173                         packet_start(SSH2_MSG_USERAUTH_PK_OK);
 174                         packet_put_string(pkalg, alen);
 175                         packet_put_string(pkblob, blen);
 176                         packet_send();
 177                         packet_write_wait();
 178                         authctxt->postponed = 1;
 179                 }
 180         }
 181         if (authenticated != 1)
 182                 auth_clear_options();
 183 done:
 184         debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
 185         if (key != NULL)
 186                 key_free(key);
 187         free(pkalg);
 188         free(pkblob);
 189         return authenticated;
 190 }
 191
 192 void
 193 pubkey_auth_info(Authctxt *authctxt, const Key *key, const char *fmt, ...)
 194 {
 195         char *fp, *extra;
 196         va_list ap;
 197         int i;
 198
 199         extra = NULL;
 200         if (fmt != NULL) {
 201                 va_start(ap, fmt);
 202                 i = vasprintf(&extra, fmt, ap);
 203                 va_end(ap);
 204                 if (i < 0 || extra == NULL)
 205                         fatal("%s: vasprintf failed", __func__);
 206         }
 207
 208         if (key_is_cert(key)) {
 209                 fp = key_fingerprint(key->cert->signature_key,
 210                     SSH_FP_MD5, SSH_FP_HEX);
 211                 auth_info(authctxt, "%s ID %s (serial %llu) CA %s %s%s%s",
 212                     key_type(key), key->cert->key_id,
 213                     (unsigned long long)key->cert->serial,
 214                     key_type(key->cert->signature_key), fp,
 215                     extra == NULL ? "" : ", ", extra == NULL ? "" : extra);
 216                 free(fp);
 217         } else {
 218                 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 219                 auth_info(authctxt, "%s %s%s%s", key_type(key), fp,
 220                     extra == NULL ? "" : ", ", extra == NULL ? "" : extra);
 221                 free(fp);
 222         }
 223         free(extra);
 224 }
 225
 226 static int
 227 match_principals_option(const char *principal_list, struct KeyCert *cert)
 228 {
 229         char *result;
 230         u_int i;
 231
 232         /* XXX percent_expand() sequences for authorized_principals? */
 233
 234         for (i = 0; i < cert->nprincipals; i++) {
 235                 if ((result = match_list(cert->principals[i],
 236                     principal_list, NULL)) != NULL) {
 237                         debug3("matched principal from key options \"%.100s\"",
 238                             result);
 239                         free(result);
 240                         return 1;
 241                 }
 242         }
 243         return 0;
 244 }
 245
 246 static int
 247 match_principals_file(char *file, struct passwd *pw, struct KeyCert *cert)
 248 {
 249         FILE *f;
 250         char line[SSH_MAX_PUBKEY_BYTES], *cp, *ep, *line_opts;
 251         u_long linenum = 0;
 252         u_int i;
 253
 254         temporarily_use_uid(pw);
 255         debug("trying authorized principals file %s", file);
 256         if ((f = auth_openprincipals(file, pw, options.strict_modes)) == NULL) {
 257                 restore_uid();
 258                 return 0;
 259         }
 260         while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
 261                 /* Skip leading whitespace. */
 262                 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
 263                         ;
 264                 /* Skip blank and comment lines. */
 265                 if ((ep = strchr(cp, '#')) != NULL)
 266                         *ep = '\0';
 267                 if (!*cp || *cp == '\n')
 268                         continue;
 269                 /* Trim trailing whitespace. */
 270                 ep = cp + strlen(cp) - 1;
 271                 while (ep > cp && (*ep == '\n' || *ep == ' ' || *ep == '\t'))
 272                         *ep-- = '\0';
 273                 /*
 274                  * If the line has internal whitespace then assume it has
 275                  * key options.
 276                  */
 277                 line_opts = NULL;
 278                 if ((ep = strrchr(cp, ' ')) != NULL ||
 279                     (ep = strrchr(cp, '\t')) != NULL) {
 280                         for (; *ep == ' ' || *ep == '\t'; ep++)
 281                                 ;
 282                         line_opts = cp;
 283                         cp = ep;
 284                 }
 285                 for (i = 0; i < cert->nprincipals; i++) {
 286                         if (strcmp(cp, cert->principals[i]) == 0) {
 287                                 debug3("matched principal \"%.100s\" "
 288                                     "from file \"%s\" on line %lu",
 289                                     cert->principals[i], file, linenum);
 290                                 if (auth_parse_options(pw, line_opts,
 291                                     file, linenum) != 1)
 292                                         continue;
 293                                 fclose(f);
 294                                 restore_uid();
 295                                 return 1;
 296                         }
 297                 }
 298         }
 299         fclose(f);
 300         restore_uid();
 301         return 0;
 302 }
 303
 304 /*
 305  * Checks whether key is allowed in authorized_keys-format file,
 306  * returns 1 if the key is allowed or 0 otherwise.
 307  */
 308 static int
 309 check_authkeys_file(FILE *f, char *file, Key* key, struct passwd *pw)
 310 {
 311         char line[SSH_MAX_PUBKEY_BYTES];
 312         const char *reason;
 313         int found_key = 0;
 314         u_long linenum = 0;
 315         Key *found;
 316         char *fp;
 317
 318         found_key = 0;
 319
 320         found = NULL;
 321         while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
 322                 char *cp, *key_options = NULL;
 323                 if (found != NULL)
 324                         key_free(found);
 325                 found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
 326                 auth_clear_options();
 327
 328                 /* Skip leading whitespace, empty and comment lines. */
 329                 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
 330                         ;
 331                 if (!*cp || *cp == '\n' || *cp == '#')
 332                         continue;
 333
 334                 if (key_read(found, &cp) != 1) {
 335                         /* no key?  check if there are options for this key */
 336                         int quoted = 0;
 337                         debug2("user_key_allowed: check options: '%s'", cp);
 338                         key_options = cp;
 339                         for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
 340                                 if (*cp == '\\' && cp[1] == '"')
 341                                         cp++;   /* Skip both */
 342                                 else if (*cp == '"')
 343                                         quoted = !quoted;
 344                         }
 345                         /* Skip remaining whitespace. */
 346                         for (; *cp == ' ' || *cp == '\t'; cp++)
 347                                 ;
 348                         if (key_read(found, &cp) != 1) {
 349                                 debug2("user_key_allowed: advance: '%s'", cp);
 350                                 /* still no key?  advance to next line*/
 351                                 continue;
 352                         }
 353                 }
 354                 if (key_is_cert(key)) {
 355                         if (!key_equal(found, key->cert->signature_key))
 356                                 continue;
 357                         if (auth_parse_options(pw, key_options, file,
 358                             linenum) != 1)
 359                                 continue;
 360                         if (!key_is_cert_authority)
 361                                 continue;
 362                         fp = key_fingerprint(found, SSH_FP_MD5,
 363                             SSH_FP_HEX);
 364                         debug("matching CA found: file %s, line %lu, %s %s",
 365                             file, linenum, key_type(found), fp);
 366                         /*
 367                          * If the user has specified a list of principals as
 368                          * a key option, then prefer that list to matching
 369                          * their username in the certificate principals list.
 370                          */
 371                         if (authorized_principals != NULL &&
 372                             !match_principals_option(authorized_principals,
 373                             key->cert)) {
 374                                 reason = "Certificate does not contain an "
 375                                     "authorized principal";
 376  fail_reason:
 377                                 free(fp);
 378                                 error("%s", reason);
 379                                 auth_debug_add("%s", reason);
 380                                 continue;
 381                         }
 382                         if (key_cert_check_authority(key, 0, 0,
 383                             authorized_principals == NULL ? pw->pw_name : NULL,
 384                             &reason) != 0)
 385                                 goto fail_reason;
 386                         if (auth_cert_options(key, pw) != 0) {
 387                                 free(fp);
 388                                 continue;
 389                         }
 390                         verbose("Accepted certificate ID \"%s\" "
 391                             "signed by %s CA %s via %s", key->cert->key_id,
 392                             key_type(found), fp, file);
 393                         free(fp);
 394                         found_key = 1;
 395                         break;
 396                 } else if (key_equal(found, key)) {
 397                         if (auth_parse_options(pw, key_options, file,
 398                             linenum) != 1)
 399                                 continue;
 400                         if (key_is_cert_authority)
 401                                 continue;
 402                         found_key = 1;
 403                         fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
 404                         debug("matching key found: file %s, line %lu %s %s",
 405                             file, linenum, key_type(found), fp);
 406                         free(fp);
 407                         break;
 408                 }
 409         }
 410         if (found != NULL)
 411                 key_free(found);
 412         if (!found_key)
 413                 debug2("key not found");
 414         return found_key;
 415 }
 416
 417 /* Authenticate a certificate key against TrustedUserCAKeys */
 418 static int
 419 user_cert_trusted_ca(struct passwd *pw, Key *key)
 420 {
 421         char *ca_fp, *principals_file = NULL;
 422         const char *reason;
 423         int ret = 0;
 424
 425         if (!key_is_cert(key) || options.trusted_user_ca_keys == NULL)
 426                 return 0;
 427
 428         ca_fp = key_fingerprint(key->cert->signature_key,
 429             SSH_FP_MD5, SSH_FP_HEX);
 430
 431         if (key_in_file(key->cert->signature_key,
 432             options.trusted_user_ca_keys, 1) != 1) {
 433                 debug2("%s: CA %s %s is not listed in %s", __func__,
 434                     key_type(key->cert->signature_key), ca_fp,
 435                     options.trusted_user_ca_keys);
 436                 goto out;
 437         }
 438         /*
 439          * If AuthorizedPrincipals is in use, then compare the certificate
 440          * principals against the names in that file rather than matching
 441          * against the username.
 442          */
 443         if ((principals_file = authorized_principals_file(pw)) != NULL) {
 444                 if (!match_principals_file(principals_file, pw, key->cert)) {
 445                         reason = "Certificate does not contain an "
 446                             "authorized principal";
 447  fail_reason:
 448                         error("%s", reason);
 449                         auth_debug_add("%s", reason);
 450                         goto out;
 451                 }
 452         }
 453         if (key_cert_check_authority(key, 0, 1,
 454             principals_file == NULL ? pw->pw_name : NULL, &reason) != 0)
 455                 goto fail_reason;
 456         if (auth_cert_options(key, pw) != 0)
 457                 goto out;
 458
 459         verbose("Accepted certificate ID \"%s\" signed by %s CA %s via %s",
 460             key->cert->key_id, key_type(key->cert->signature_key), ca_fp,
 461             options.trusted_user_ca_keys);
 462         ret = 1;
 463
 464  out:
 465         free(principals_file);
 466         free(ca_fp);
 467         return ret;
 468 }
 469
 470 /*
 471  * Checks whether key is allowed in file.
 472  * returns 1 if the key is allowed or 0 otherwise.
 473  */
 474 static int
 475 user_key_allowed2(struct passwd *pw, Key *key, char *file)
 476 {
 477         FILE *f;
 478         int found_key = 0;
 479
 480         /* Temporarily use the user's uid. */
 481         temporarily_use_uid(pw);
 482
 483         debug("trying public key file %s", file);
 484         if ((f = auth_openkeyfile(file, pw, options.strict_modes)) != NULL) {
 485                 found_key = check_authkeys_file(f, file, key, pw);
 486                 fclose(f);
 487         }
 488
 489         restore_uid();
 490         return found_key;
 491 }
 492
 493 /*
 494  * Checks whether key is allowed in output of command.
 495  * returns 1 if the key is allowed or 0 otherwise.
 496  */
 497 static int
 498 user_key_command_allowed2(struct passwd *user_pw, Key *key)
 499 {
 500         FILE *f;
 501         int ok, found_key = 0;
 502         struct passwd *pw;
 503         struct stat st;
 504         int status, devnull, p[2], i;
 505         pid_t pid;
 506         char *username, errmsg[512];
 507
 508         if (options.authorized_keys_command == NULL ||
 509             options.authorized_keys_command[0] != '/')
 510                 return 0;
 511
 512         if (options.authorized_keys_command_user == NULL) {
 513                 error("No user for AuthorizedKeysCommand specified, skipping");
 514                 return 0;
 515         }
 516
 517         username = percent_expand(options.authorized_keys_command_user,
 518             "u", user_pw->pw_name, (char *)NULL);
 519         pw = getpwnam(username);
 520         if (pw == NULL) {
 521                 error("AuthorizedKeysCommandUser \"%s\" not found: %s",
 522                     username, strerror(errno));
 523                 free(username);
 524                 return 0;
 525         }
 526         free(username);
 527
 528         temporarily_use_uid(pw);
 529
 530         if (stat(options.authorized_keys_command, &st) < 0) {
 531                 error("Could not stat AuthorizedKeysCommand \"%s\": %s",
 532                     options.authorized_keys_command, strerror(errno));
 533                 goto out;
 534         }
 535         if (auth_secure_path(options.authorized_keys_command, &st, NULL, 0,
 536             errmsg, sizeof(errmsg)) != 0) {
 537                 error("Unsafe AuthorizedKeysCommand: %s", errmsg);
 538                 goto out;
 539         }
 540
 541         if (pipe(p) != 0) {
 542                 error("%s: pipe: %s", __func__, strerror(errno));
 543                 goto out;
 544         }
 545
 546         debug3("Running AuthorizedKeysCommand: \"%s %s\" as \"%s\"",
 547             options.authorized_keys_command, user_pw->pw_name, pw->pw_name);
 548
 549         /*
 550          * Don't want to call this in the child, where it can fatal() and
 551          * run cleanup_exit() code.
 552          */
 553         restore_uid();
 554
 555         switch ((pid = fork())) {
 556         case -1: /* error */
 557                 error("%s: fork: %s", __func__, strerror(errno));
 558                 close(p[0]);
 559                 close(p[1]);
 560                 return 0;
 561         case 0: /* child */
 562                 for (i = 0; i < NSIG; i++)
 563                         signal(i, SIG_DFL);
 564
 565                 if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
 566                         error("%s: open %s: %s", __func__, _PATH_DEVNULL,
 567                             strerror(errno));
 568                         _exit(1);
 569                 }
 570                 /* Keep stderr around a while longer to catch errors */
 571                 if (dup2(devnull, STDIN_FILENO) == -1 ||
 572                     dup2(p[1], STDOUT_FILENO) == -1) {
 573                         error("%s: dup2: %s", __func__, strerror(errno));
 574                         _exit(1);
 575                 }
 576                 closefrom(STDERR_FILENO + 1);
 577
 578                 /* Don't use permanently_set_uid() here to avoid fatal() */
 579                 if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) != 0) {
 580                         error("setresgid %u: %s", (u_int)pw->pw_gid,
 581                             strerror(errno));
 582                         _exit(1);
 583                 }
 584                 if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) != 0) {
 585                         error("setresuid %u: %s", (u_int)pw->pw_uid,
 586                             strerror(errno));
 587                         _exit(1);
 588                 }
 589                 /* stdin is pointed to /dev/null at this point */
 590                 if (dup2(STDIN_FILENO, STDERR_FILENO) == -1) {
 591                         error("%s: dup2: %s", __func__, strerror(errno));
 592                         _exit(1);
 593                 }
 594
 595                 execl(options.authorized_keys_command,
 596                     options.authorized_keys_command, user_pw->pw_name, NULL);
 597
 598                 error("AuthorizedKeysCommand %s exec failed: %s",
 599                     options.authorized_keys_command, strerror(errno));
 600                 _exit(127);
 601         default: /* parent */
 602                 break;
 603         }
 604
 605         temporarily_use_uid(pw);
 606
 607         close(p[1]);
 608         if ((f = fdopen(p[0], "r")) == NULL) {
 609                 error("%s: fdopen: %s", __func__, strerror(errno));
 610                 close(p[0]);
 611                 /* Don't leave zombie child */
 612                 kill(pid, SIGTERM);
 613                 while (waitpid(pid, NULL, 0) == -1 && errno == EINTR)
 614                         ;
 615                 goto out;
 616         }
 617         ok = check_authkeys_file(f, options.authorized_keys_command, key, pw);
 618         fclose(f);
 619
 620         while (waitpid(pid, &status, 0) == -1) {
 621                 if (errno != EINTR) {
 622                         error("%s: waitpid: %s", __func__, strerror(errno));
 623                         goto out;
 624                 }
 625         }
 626         if (WIFSIGNALED(status)) {
 627                 error("AuthorizedKeysCommand %s exited on signal %d",
 628                     options.authorized_keys_command, WTERMSIG(status));
 629                 goto out;
 630         } else if (WEXITSTATUS(status) != 0) {
 631                 error("AuthorizedKeysCommand %s returned status %d",
 632                     options.authorized_keys_command, WEXITSTATUS(status));
 633                 goto out;
 634         }
 635         found_key = ok;
 636  out:
 637         restore_uid();
 638         return found_key;
 639 }
 640
 641 /*
 642  * Check whether key authenticates and authorises the user.
 643  */
 644 int
 645 user_key_allowed(struct passwd *pw, Key *key)
 646 {
 647         u_int success, i;
 648         char *file;
 649
 650         if (auth_key_is_revoked(key))
 651                 return 0;
 652         if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key))
 653                 return 0;
 654
 655         success = user_cert_trusted_ca(pw, key);
 656         if (success)
 657                 return success;
 658
 659         success = user_key_command_allowed2(pw, key);
 660         if (success > 0)
 661                 return success;
 662
 663         for (i = 0; !success && i < options.num_authkeys_files; i++) {
 664
 665                 if (strcasecmp(options.authorized_keys_files[i], "none") == 0)
 666                         continue;
 667                 file = expand_authorized_keys(
 668                     options.authorized_keys_files[i], pw);
 669
 670                 success = user_key_allowed2(pw, key, file);
 671                 free(file);
 672         }
 673
 674         return success;
 675 }
 676
 677 Authmethod method_pubkey = {
 678         "publickey",
 679         userauth_pubkey,
 680         &options.pubkey_authentication
 681 };