crypto/openssh/auth2-pubkey.c

   1 /* $OpenBSD: auth2-pubkey.c,v 1.41 2014/07/15 15:54:14 millert 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 "misc.h"
  52 #include "servconf.h"
  53 #include "compat.h"
  54 #include "key.h"
  55 #include "hostfile.h"
  56 #include "auth.h"
  57 #include "pathnames.h"
  58 #include "uidswap.h"
  59 #include "auth-options.h"
  60 #include "canohost.h"
  61 #ifdef GSSAPI
  62 #include "ssh-gss.h"
  63 #endif
  64 #include "monitor_wrap.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 (key_type_plain(key->type) == KEY_RSA &&
 120             (datafellows & SSH_BUG_RSASIGMD5) != 0) {
 121                 logit("Refusing RSA key because client uses unsafe "
 122                     "signature scheme");
 123                 goto done;
 124         }
 125         if (have_sig) {
 126                 sig = packet_get_string(&slen);
 127                 packet_check_eom();
 128                 buffer_init(&b);
 129                 if (datafellows & SSH_OLD_SESSIONID) {
 130                         buffer_append(&b, session_id2, session_id2_len);
 131                 } else {
 132                         buffer_put_string(&b, session_id2, session_id2_len);
 133                 }
 134                 /* reconstruct packet */
 135                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
 136                 xasprintf(&userstyle, "%s%s%s", authctxt->user,
 137                     authctxt->style ? ":" : "",
 138                     authctxt->style ? authctxt->style : "");
 139                 buffer_put_cstring(&b, userstyle);
 140                 free(userstyle);
 141                 buffer_put_cstring(&b,
 142                     datafellows & SSH_BUG_PKSERVICE ?
 143                     "ssh-userauth" :
 144                     authctxt->service);
 145                 if (datafellows & SSH_BUG_PKAUTH) {
 146                         buffer_put_char(&b, have_sig);
 147                 } else {
 148                         buffer_put_cstring(&b, "publickey");
 149                         buffer_put_char(&b, have_sig);
 150                         buffer_put_cstring(&b, pkalg);
 151                 }
 152                 buffer_put_string(&b, pkblob, blen);
 153 #ifdef DEBUG_PK
 154                 buffer_dump(&b);
 155 #endif
 156                 pubkey_auth_info(authctxt, key, NULL);
 157
 158                 /* test for correct signature */
 159                 authenticated = 0;
 160                 if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
 161                     PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
 162                     buffer_len(&b))) == 1)
 163                         authenticated = 1;
 164                 buffer_free(&b);
 165                 free(sig);
 166         } else {
 167                 debug("test whether pkalg/pkblob are acceptable");
 168                 packet_check_eom();
 169
 170                 /* XXX fake reply and always send PK_OK ? */
 171                 /*
 172                  * XXX this allows testing whether a user is allowed
 173                  * to login: if you happen to have a valid pubkey this
 174                  * message is sent. the message is NEVER sent at all
 175                  * if a user is not allowed to login. is this an
 176                  * issue? -markus
 177                  */
 178                 if (PRIVSEP(user_key_allowed(authctxt->pw, key))) {
 179                         packet_start(SSH2_MSG_USERAUTH_PK_OK);
 180                         packet_put_string(pkalg, alen);
 181                         packet_put_string(pkblob, blen);
 182                         packet_send();
 183                         packet_write_wait();
 184                         authctxt->postponed = 1;
 185                 }
 186         }
 187         if (authenticated != 1)
 188                 auth_clear_options();
 189 done:
 190         debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
 191         if (key != NULL)
 192                 key_free(key);
 193         free(pkalg);
 194         free(pkblob);
 195         return authenticated;
 196 }
 197
 198 void
 199 pubkey_auth_info(Authctxt *authctxt, const Key *key, const char *fmt, ...)
 200 {
 201         char *fp, *extra;
 202         va_list ap;
 203         int i;
 204
 205         extra = NULL;
 206         if (fmt != NULL) {
 207                 va_start(ap, fmt);
 208                 i = vasprintf(&extra, fmt, ap);
 209                 va_end(ap);
 210                 if (i < 0 || extra == NULL)
 211                         fatal("%s: vasprintf failed", __func__);
 212         }
 213
 214         if (key_is_cert(key)) {
 215                 fp = key_fingerprint(key->cert->signature_key,
 216                     SSH_FP_MD5, SSH_FP_HEX);
 217                 auth_info(authctxt, "%s ID %s (serial %llu) CA %s %s%s%s",
 218                     key_type(key), key->cert->key_id,
 219                     (unsigned long long)key->cert->serial,
 220                     key_type(key->cert->signature_key), fp,
 221                     extra == NULL ? "" : ", ", extra == NULL ? "" : extra);
 222                 free(fp);
 223         } else {
 224                 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 225                 auth_info(authctxt, "%s %s%s%s", key_type(key), fp,
 226                     extra == NULL ? "" : ", ", extra == NULL ? "" : extra);
 227                 free(fp);
 228         }
 229         free(extra);
 230 }
 231
 232 static int
 233 match_principals_option(const char *principal_list, struct sshkey_cert *cert)
 234 {
 235         char *result;
 236         u_int i;
 237
 238         /* XXX percent_expand() sequences for authorized_principals? */
 239
 240         for (i = 0; i < cert->nprincipals; i++) {
 241                 if ((result = match_list(cert->principals[i],
 242                     principal_list, NULL)) != NULL) {
 243                         debug3("matched principal from key options \"%.100s\"",
 244                             result);
 245                         free(result);
 246                         return 1;
 247                 }
 248         }
 249         return 0;
 250 }
 251
 252 static int
 253 match_principals_file(char *file, struct passwd *pw, struct sshkey_cert *cert)
 254 {
 255         FILE *f;
 256         char line[SSH_MAX_PUBKEY_BYTES], *cp, *ep, *line_opts;
 257         u_long linenum = 0;
 258         u_int i;
 259
 260         temporarily_use_uid(pw);
 261         debug("trying authorized principals file %s", file);
 262         if ((f = auth_openprincipals(file, pw, options.strict_modes)) == NULL) {
 263                 restore_uid();
 264                 return 0;
 265         }
 266         while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
 267                 /* Skip leading whitespace. */
 268                 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
 269                         ;
 270                 /* Skip blank and comment lines. */
 271                 if ((ep = strchr(cp, '#')) != NULL)
 272                         *ep = '\0';
 273                 if (!*cp || *cp == '\n')
 274                         continue;
 275                 /* Trim trailing whitespace. */
 276                 ep = cp + strlen(cp) - 1;
 277                 while (ep > cp && (*ep == '\n' || *ep == ' ' || *ep == '\t'))
 278                         *ep-- = '\0';
 279                 /*
 280                  * If the line has internal whitespace then assume it has
 281                  * key options.
 282                  */
 283                 line_opts = NULL;
 284                 if ((ep = strrchr(cp, ' ')) != NULL ||
 285                     (ep = strrchr(cp, '\t')) != NULL) {
 286                         for (; *ep == ' ' || *ep == '\t'; ep++)
 287                                 ;
 288                         line_opts = cp;
 289                         cp = ep;
 290                 }
 291                 for (i = 0; i < cert->nprincipals; i++) {
 292                         if (strcmp(cp, cert->principals[i]) == 0) {
 293                                 debug3("matched principal \"%.100s\" "
 294                                     "from file \"%s\" on line %lu",
 295                                     cert->principals[i], file, linenum);
 296                                 if (auth_parse_options(pw, line_opts,
 297                                     file, linenum) != 1)
 298                                         continue;
 299                                 fclose(f);
 300                                 restore_uid();
 301                                 return 1;
 302                         }
 303                 }
 304         }
 305         fclose(f);
 306         restore_uid();
 307         return 0;
 308 }
 309
 310 /*
 311  * Checks whether key is allowed in authorized_keys-format file,
 312  * returns 1 if the key is allowed or 0 otherwise.
 313  */
 314 static int
 315 check_authkeys_file(FILE *f, char *file, Key* key, struct passwd *pw)
 316 {
 317         char line[SSH_MAX_PUBKEY_BYTES];
 318         const char *reason;
 319         int found_key = 0;
 320         u_long linenum = 0;
 321         Key *found;
 322         char *fp;
 323
 324         found_key = 0;
 325
 326         found = NULL;
 327         while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
 328                 char *cp, *key_options = NULL;
 329                 if (found != NULL)
 330                         key_free(found);
 331                 found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
 332                 auth_clear_options();
 333
 334                 /* Skip leading whitespace, empty and comment lines. */
 335                 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
 336                         ;
 337                 if (!*cp || *cp == '\n' || *cp == '#')
 338                         continue;
 339
 340                 if (key_read(found, &cp) != 1) {
 341                         /* no key?  check if there are options for this key */
 342                         int quoted = 0;
 343                         debug2("user_key_allowed: check options: '%s'", cp);
 344                         key_options = cp;
 345                         for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
 346                                 if (*cp == '\\' && cp[1] == '"')
 347                                         cp++;   /* Skip both */
 348                                 else if (*cp == '"')
 349                                         quoted = !quoted;
 350                         }
 351                         /* Skip remaining whitespace. */
 352                         for (; *cp == ' ' || *cp == '\t'; cp++)
 353                                 ;
 354                         if (key_read(found, &cp) != 1) {
 355                                 debug2("user_key_allowed: advance: '%s'", cp);
 356                                 /* still no key?  advance to next line*/
 357                                 continue;
 358                         }
 359                 }
 360                 if (key_is_cert(key)) {
 361                         if (!key_equal(found, key->cert->signature_key))
 362                                 continue;
 363                         if (auth_parse_options(pw, key_options, file,
 364                             linenum) != 1)
 365                                 continue;
 366                         if (!key_is_cert_authority)
 367                                 continue;
 368                         fp = key_fingerprint(found, SSH_FP_MD5,
 369                             SSH_FP_HEX);
 370                         debug("matching CA found: file %s, line %lu, %s %s",
 371                             file, linenum, key_type(found), fp);
 372                         /*
 373                          * If the user has specified a list of principals as
 374                          * a key option, then prefer that list to matching
 375                          * their username in the certificate principals list.
 376                          */
 377                         if (authorized_principals != NULL &&
 378                             !match_principals_option(authorized_principals,
 379                             key->cert)) {
 380                                 reason = "Certificate does not contain an "
 381                                     "authorized principal";
 382  fail_reason:
 383                                 free(fp);
 384                                 error("%s", reason);
 385                                 auth_debug_add("%s", reason);
 386                                 continue;
 387                         }
 388                         if (key_cert_check_authority(key, 0, 0,
 389                             authorized_principals == NULL ? pw->pw_name : NULL,
 390                             &reason) != 0)
 391                                 goto fail_reason;
 392                         if (auth_cert_options(key, pw) != 0) {
 393                                 free(fp);
 394                                 continue;
 395                         }
 396                         verbose("Accepted certificate ID \"%s\" "
 397                             "signed by %s CA %s via %s", key->cert->key_id,
 398                             key_type(found), fp, file);
 399                         free(fp);
 400                         found_key = 1;
 401                         break;
 402                 } else if (key_equal(found, key)) {
 403                         if (auth_parse_options(pw, key_options, file,
 404                             linenum) != 1)
 405                                 continue;
 406                         if (key_is_cert_authority)
 407                                 continue;
 408                         found_key = 1;
 409                         fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
 410                         debug("matching key found: file %s, line %lu %s %s",
 411                             file, linenum, key_type(found), fp);
 412                         free(fp);
 413                         break;
 414                 }
 415         }
 416         if (found != NULL)
 417                 key_free(found);
 418         if (!found_key)
 419                 debug2("key not found");
 420         return found_key;
 421 }
 422
 423 /* Authenticate a certificate key against TrustedUserCAKeys */
 424 static int
 425 user_cert_trusted_ca(struct passwd *pw, Key *key)
 426 {
 427         char *ca_fp, *principals_file = NULL;
 428         const char *reason;
 429         int ret = 0;
 430
 431         if (!key_is_cert(key) || options.trusted_user_ca_keys == NULL)
 432                 return 0;
 433
 434         ca_fp = key_fingerprint(key->cert->signature_key,
 435             SSH_FP_MD5, SSH_FP_HEX);
 436
 437         if (key_in_file(key->cert->signature_key,
 438             options.trusted_user_ca_keys, 1) != 1) {
 439                 debug2("%s: CA %s %s is not listed in %s", __func__,
 440                     key_type(key->cert->signature_key), ca_fp,
 441                     options.trusted_user_ca_keys);
 442                 goto out;
 443         }
 444         /*
 445          * If AuthorizedPrincipals is in use, then compare the certificate
 446          * principals against the names in that file rather than matching
 447          * against the username.
 448          */
 449         if ((principals_file = authorized_principals_file(pw)) != NULL) {
 450                 if (!match_principals_file(principals_file, pw, key->cert)) {
 451                         reason = "Certificate does not contain an "
 452                             "authorized principal";
 453  fail_reason:
 454                         error("%s", reason);
 455                         auth_debug_add("%s", reason);
 456                         goto out;
 457                 }
 458         }
 459         if (key_cert_check_authority(key, 0, 1,
 460             principals_file == NULL ? pw->pw_name : NULL, &reason) != 0)
 461                 goto fail_reason;
 462         if (auth_cert_options(key, pw) != 0)
 463                 goto out;
 464
 465         verbose("Accepted certificate ID \"%s\" signed by %s CA %s via %s",
 466             key->cert->key_id, key_type(key->cert->signature_key), ca_fp,
 467             options.trusted_user_ca_keys);
 468         ret = 1;
 469
 470  out:
 471         free(principals_file);
 472         free(ca_fp);
 473         return ret;
 474 }
 475
 476 /*
 477  * Checks whether key is allowed in file.
 478  * returns 1 if the key is allowed or 0 otherwise.
 479  */
 480 static int
 481 user_key_allowed2(struct passwd *pw, Key *key, char *file)
 482 {
 483         FILE *f;
 484         int found_key = 0;
 485
 486         /* Temporarily use the user's uid. */
 487         temporarily_use_uid(pw);
 488
 489         debug("trying public key file %s", file);
 490         if ((f = auth_openkeyfile(file, pw, options.strict_modes)) != NULL) {
 491                 found_key = check_authkeys_file(f, file, key, pw);
 492                 fclose(f);
 493         }
 494
 495         restore_uid();
 496         return found_key;
 497 }
 498
 499 /*
 500  * Checks whether key is allowed in output of command.
 501  * returns 1 if the key is allowed or 0 otherwise.
 502  */
 503 static int
 504 user_key_command_allowed2(struct passwd *user_pw, Key *key)
 505 {
 506         FILE *f;
 507         int ok, found_key = 0;
 508         struct passwd *pw;
 509         struct stat st;
 510         int status, devnull, p[2], i;
 511         pid_t pid;
 512         char *username, errmsg[512];
 513
 514         if (options.authorized_keys_command == NULL ||
 515             options.authorized_keys_command[0] != '/')
 516                 return 0;
 517
 518         if (options.authorized_keys_command_user == NULL) {
 519                 error("No user for AuthorizedKeysCommand specified, skipping");
 520                 return 0;
 521         }
 522
 523         username = percent_expand(options.authorized_keys_command_user,
 524             "u", user_pw->pw_name, (char *)NULL);
 525         pw = getpwnam(username);
 526         if (pw == NULL) {
 527                 error("AuthorizedKeysCommandUser \"%s\" not found: %s",
 528                     username, strerror(errno));
 529                 free(username);
 530                 return 0;
 531         }
 532         free(username);
 533
 534         temporarily_use_uid(pw);
 535
 536         if (stat(options.authorized_keys_command, &st) < 0) {
 537                 error("Could not stat AuthorizedKeysCommand \"%s\": %s",
 538                     options.authorized_keys_command, strerror(errno));
 539                 goto out;
 540         }
 541         if (auth_secure_path(options.authorized_keys_command, &st, NULL, 0,
 542             errmsg, sizeof(errmsg)) != 0) {
 543                 error("Unsafe AuthorizedKeysCommand: %s", errmsg);
 544                 goto out;
 545         }
 546
 547         if (pipe(p) != 0) {
 548                 error("%s: pipe: %s", __func__, strerror(errno));
 549                 goto out;
 550         }
 551
 552         debug3("Running AuthorizedKeysCommand: \"%s %s\" as \"%s\"",
 553             options.authorized_keys_command, user_pw->pw_name, pw->pw_name);
 554
 555         /*
 556          * Don't want to call this in the child, where it can fatal() and
 557          * run cleanup_exit() code.
 558          */
 559         restore_uid();
 560
 561         switch ((pid = fork())) {
 562         case -1: /* error */
 563                 error("%s: fork: %s", __func__, strerror(errno));
 564                 close(p[0]);
 565                 close(p[1]);
 566                 return 0;
 567         case 0: /* child */
 568                 for (i = 0; i < NSIG; i++)
 569                         signal(i, SIG_DFL);
 570
 571                 if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
 572                         error("%s: open %s: %s", __func__, _PATH_DEVNULL,
 573                             strerror(errno));
 574                         _exit(1);
 575                 }
 576                 /* Keep stderr around a while longer to catch errors */
 577                 if (dup2(devnull, STDIN_FILENO) == -1 ||
 578                     dup2(p[1], STDOUT_FILENO) == -1) {
 579                         error("%s: dup2: %s", __func__, strerror(errno));
 580                         _exit(1);
 581                 }
 582                 closefrom(STDERR_FILENO + 1);
 583
 584                 /* Don't use permanently_set_uid() here to avoid fatal() */
 585                 if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) != 0) {
 586                         error("setresgid %u: %s", (u_int)pw->pw_gid,
 587                             strerror(errno));
 588                         _exit(1);
 589                 }
 590                 if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) != 0) {
 591                         error("setresuid %u: %s", (u_int)pw->pw_uid,
 592                             strerror(errno));
 593                         _exit(1);
 594                 }
 595                 /* stdin is pointed to /dev/null at this point */
 596                 if (dup2(STDIN_FILENO, STDERR_FILENO) == -1) {
 597                         error("%s: dup2: %s", __func__, strerror(errno));
 598                         _exit(1);
 599                 }
 600
 601                 execl(options.authorized_keys_command,
 602                     options.authorized_keys_command, user_pw->pw_name, NULL);
 603
 604                 error("AuthorizedKeysCommand %s exec failed: %s",
 605                     options.authorized_keys_command, strerror(errno));
 606                 _exit(127);
 607         default: /* parent */
 608                 break;
 609         }
 610
 611         temporarily_use_uid(pw);
 612
 613         close(p[1]);
 614         if ((f = fdopen(p[0], "r")) == NULL) {
 615                 error("%s: fdopen: %s", __func__, strerror(errno));
 616                 close(p[0]);
 617                 /* Don't leave zombie child */
 618                 kill(pid, SIGTERM);
 619                 while (waitpid(pid, NULL, 0) == -1 && errno == EINTR)
 620                         ;
 621                 goto out;
 622         }
 623         ok = check_authkeys_file(f, options.authorized_keys_command, key, pw);
 624         fclose(f);
 625
 626         while (waitpid(pid, &status, 0) == -1) {
 627                 if (errno != EINTR) {
 628                         error("%s: waitpid: %s", __func__, strerror(errno));
 629                         goto out;
 630                 }
 631         }
 632         if (WIFSIGNALED(status)) {
 633                 error("AuthorizedKeysCommand %s exited on signal %d",
 634                     options.authorized_keys_command, WTERMSIG(status));
 635                 goto out;
 636         } else if (WEXITSTATUS(status) != 0) {
 637                 error("AuthorizedKeysCommand %s returned status %d",
 638                     options.authorized_keys_command, WEXITSTATUS(status));
 639                 goto out;
 640         }
 641         found_key = ok;
 642  out:
 643         restore_uid();
 644         return found_key;
 645 }
 646
 647 /*
 648  * Check whether key authenticates and authorises the user.
 649  */
 650 int
 651 user_key_allowed(struct passwd *pw, Key *key)
 652 {
 653         u_int success, i;
 654         char *file;
 655
 656         if (auth_key_is_revoked(key))
 657                 return 0;
 658         if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key))
 659                 return 0;
 660
 661         success = user_cert_trusted_ca(pw, key);
 662         if (success)
 663                 return success;
 664
 665         success = user_key_command_allowed2(pw, key);
 666         if (success > 0)
 667                 return success;
 668
 669         for (i = 0; !success && i < options.num_authkeys_files; i++) {
 670
 671                 if (strcasecmp(options.authorized_keys_files[i], "none") == 0)
 672                         continue;
 673                 file = expand_authorized_keys(
 674                     options.authorized_keys_files[i], pw);
 675
 676                 success = user_key_allowed2(pw, key, file);
 677                 free(file);
 678         }
 679
 680         return success;
 681 }
 682
 683 Authmethod method_pubkey = {
 684         "publickey",
 685         userauth_pubkey,
 686         &options.pubkey_authentication
 687 };