crypto/openssh/auth2.c

   1 /* $OpenBSD: auth2.c,v 1.143 2017/06/24 06:34:38 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/uio.h>
  31
  32 #include <fcntl.h>
  33 #include <limits.h>
  34 #include <pwd.h>
  35 #include <stdarg.h>
  36 #include <string.h>
  37 #include <unistd.h>
  38
  39 #include "atomicio.h"
  40 #include "xmalloc.h"
  41 #include "ssh2.h"
  42 #include "packet.h"
  43 #include "log.h"
  44 #include "buffer.h"
  45 #include "misc.h"
  46 #include "servconf.h"
  47 #include "compat.h"
  48 #include "key.h"
  49 #include "hostfile.h"
  50 #include "auth.h"
  51 #include "dispatch.h"
  52 #include "pathnames.h"
  53 #include "buffer.h"
  54
  55 #ifdef GSSAPI
  56 #include "ssh-gss.h"
  57 #endif
  58 #include "monitor_wrap.h"
  59 #include "ssherr.h"
  60
  61 /* import */
  62 extern ServerOptions options;
  63 extern u_char *session_id2;
  64 extern u_int session_id2_len;
  65 extern Buffer loginmsg;
  66
  67 /* methods */
  68
  69 extern Authmethod method_none;
  70 extern Authmethod method_pubkey;
  71 extern Authmethod method_passwd;
  72 extern Authmethod method_kbdint;
  73 extern Authmethod method_hostbased;
  74 #ifdef GSSAPI
  75 extern Authmethod method_gssapi;
  76 #endif
  77
  78 Authmethod *authmethods[] = {
  79         &method_none,
  80         &method_pubkey,
  81 #ifdef GSSAPI
  82         &method_gssapi,
  83 #endif
  84         &method_passwd,
  85         &method_kbdint,
  86         &method_hostbased,
  87         NULL
  88 };
  89
  90 /* protocol */
  91
  92 static int input_service_request(int, u_int32_t, struct ssh *);
  93 static int input_userauth_request(int, u_int32_t, struct ssh *);
  94
  95 /* helper */
  96 static Authmethod *authmethod_lookup(Authctxt *, const char *);
  97 static char *authmethods_get(Authctxt *authctxt);
  98
  99 #define MATCH_NONE      0       /* method or submethod mismatch */
 100 #define MATCH_METHOD    1       /* method matches (no submethod specified) */
 101 #define MATCH_BOTH      2       /* method and submethod match */
 102 #define MATCH_PARTIAL   3       /* method matches, submethod can't be checked */
 103 static int list_starts_with(const char *, const char *, const char *);
 104
 105 char *
 106 auth2_read_banner(void)
 107 {
 108         struct stat st;
 109         char *banner = NULL;
 110         size_t len, n;
 111         int fd;
 112
 113         if ((fd = open(options.banner, O_RDONLY)) == -1)
 114                 return (NULL);
 115         if (fstat(fd, &st) == -1) {
 116                 close(fd);
 117                 return (NULL);
 118         }
 119         if (st.st_size <= 0 || st.st_size > 1*1024*1024) {
 120                 close(fd);
 121                 return (NULL);
 122         }
 123
 124         len = (size_t)st.st_size;               /* truncate */
 125         banner = xmalloc(len + 1);
 126         n = atomicio(read, fd, banner, len);
 127         close(fd);
 128
 129         if (n != len) {
 130                 free(banner);
 131                 return (NULL);
 132         }
 133         banner[n] = '\0';
 134
 135         return (banner);
 136 }
 137
 138 void
 139 userauth_send_banner(const char *msg)
 140 {
 141         if (datafellows & SSH_BUG_BANNER)
 142                 return;
 143
 144         packet_start(SSH2_MSG_USERAUTH_BANNER);
 145         packet_put_cstring(msg);
 146         packet_put_cstring("");         /* language, unused */
 147         packet_send();
 148         debug("%s: sent", __func__);
 149 }
 150
 151 static void
 152 userauth_banner(void)
 153 {
 154         char *banner = NULL;
 155
 156         if (options.banner == NULL || (datafellows & SSH_BUG_BANNER) != 0)
 157                 return;
 158
 159         if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
 160                 goto done;
 161         userauth_send_banner(banner);
 162
 163 done:
 164         free(banner);
 165 }
 166
 167 /*
 168  * loop until authctxt->success == TRUE
 169  */
 170 void
 171 do_authentication2(Authctxt *authctxt)
 172 {
 173         struct ssh *ssh = active_state;         /* XXX */
 174         ssh->authctxt = authctxt;               /* XXX move to caller */
 175         ssh_dispatch_init(ssh, &dispatch_protocol_error);
 176         ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request);
 177         ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success);
 178         ssh->authctxt = NULL;
 179 }
 180
 181 /*ARGSUSED*/
 182 static int
 183 input_service_request(int type, u_int32_t seq, struct ssh *ssh)
 184 {
 185         Authctxt *authctxt = ssh->authctxt;
 186         u_int len;
 187         int acceptit = 0;
 188         char *service = packet_get_cstring(&len);
 189         packet_check_eom();
 190
 191         if (authctxt == NULL)
 192                 fatal("input_service_request: no authctxt");
 193
 194         if (strcmp(service, "ssh-userauth") == 0) {
 195                 if (!authctxt->success) {
 196                         acceptit = 1;
 197                         /* now we can handle user-auth requests */
 198                         ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
 199                 }
 200         }
 201         /* XXX all other service requests are denied */
 202
 203         if (acceptit) {
 204                 packet_start(SSH2_MSG_SERVICE_ACCEPT);
 205                 packet_put_cstring(service);
 206                 packet_send();
 207                 packet_write_wait();
 208         } else {
 209                 debug("bad service request %s", service);
 210                 packet_disconnect("bad service request %s", service);
 211         }
 212         free(service);
 213         return 0;
 214 }
 215
 216 /*ARGSUSED*/
 217 static int
 218 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh)
 219 {
 220         Authctxt *authctxt = ssh->authctxt;
 221         Authmethod *m = NULL;
 222         char *user, *service, *method, *style = NULL;
 223         int authenticated = 0;
 224
 225         if (authctxt == NULL)
 226                 fatal("input_userauth_request: no authctxt");
 227
 228         user = packet_get_cstring(NULL);
 229         service = packet_get_cstring(NULL);
 230         method = packet_get_cstring(NULL);
 231         debug("userauth-request for user %s service %s method %s", user, service, method);
 232         debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
 233
 234         if ((style = strchr(user, ':')) != NULL)
 235                 *style++ = 0;
 236
 237         if (authctxt->attempt++ == 0) {
 238                 /* setup auth context */
 239                 authctxt->pw = PRIVSEP(getpwnamallow(user));
 240                 authctxt->user = xstrdup(user);
 241                 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
 242                         authctxt->valid = 1;
 243                         debug2("%s: setting up authctxt for %s",
 244                             __func__, user);
 245                 } else {
 246                         /* Invalid user, fake password information */
 247                         authctxt->pw = fakepw();
 248 #ifdef SSH_AUDIT_EVENTS
 249                         PRIVSEP(audit_event(SSH_INVALID_USER));
 250 #endif
 251                 }
 252 #ifdef USE_PAM
 253                 if (options.use_pam)
 254                         PRIVSEP(start_pam(authctxt));
 255 #endif
 256                 ssh_packet_set_log_preamble(ssh, "%suser %s",
 257                     authctxt->valid ? "authenticating " : "invalid ", user);
 258                 setproctitle("%s%s", authctxt->valid ? user : "unknown",
 259                     use_privsep ? " [net]" : "");
 260                 authctxt->service = xstrdup(service);
 261                 authctxt->style = style ? xstrdup(style) : NULL;
 262                 if (use_privsep)
 263                         mm_inform_authserv(service, style);
 264                 userauth_banner();
 265                 if (auth2_setup_methods_lists(authctxt) != 0)
 266                         packet_disconnect("no authentication methods enabled");
 267         } else if (strcmp(user, authctxt->user) != 0 ||
 268             strcmp(service, authctxt->service) != 0) {
 269                 packet_disconnect("Change of username or service not allowed: "
 270                     "(%s,%s) -> (%s,%s)",
 271                     authctxt->user, authctxt->service, user, service);
 272         }
 273         /* reset state */
 274         auth2_challenge_stop(ssh);
 275
 276 #ifdef GSSAPI
 277         /* XXX move to auth2_gssapi_stop() */
 278         ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
 279         ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
 280 #endif
 281
 282         auth2_authctxt_reset_info(authctxt);
 283         authctxt->postponed = 0;
 284         authctxt->server_caused_failure = 0;
 285
 286         /* try to authenticate user */
 287         m = authmethod_lookup(authctxt, method);
 288         if (m != NULL && authctxt->failures < options.max_authtries) {
 289                 debug2("input_userauth_request: try method %s", method);
 290                 authenticated = m->userauth(ssh);
 291         }
 292         userauth_finish(ssh, authenticated, method, NULL);
 293
 294         free(service);
 295         free(user);
 296         free(method);
 297         return 0;
 298 }
 299
 300 void
 301 userauth_finish(struct ssh *ssh, int authenticated, const char *method,
 302     const char *submethod)
 303 {
 304         Authctxt *authctxt = ssh->authctxt;
 305         char *methods;
 306         int partial = 0;
 307
 308         if (!authctxt->valid && authenticated)
 309                 fatal("INTERNAL ERROR: authenticated invalid user %s",
 310                     authctxt->user);
 311         if (authenticated && authctxt->postponed)
 312                 fatal("INTERNAL ERROR: authenticated and postponed");
 313
 314         /* Special handling for root */
 315         if (authenticated && authctxt->pw->pw_uid == 0 &&
 316             !auth_root_allowed(method)) {
 317                 authenticated = 0;
 318 #ifdef SSH_AUDIT_EVENTS
 319                 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
 320 #endif
 321         }
 322
 323         if (authenticated && options.num_auth_methods != 0) {
 324                 if (!auth2_update_methods_lists(authctxt, method, submethod)) {
 325                         authenticated = 0;
 326                         partial = 1;
 327                 }
 328         }
 329
 330         /* Log before sending the reply */
 331         auth_log(authctxt, authenticated, partial, method, submethod);
 332
 333         /* Update information exposed to session */
 334         if (authenticated || partial)
 335                 auth2_update_session_info(authctxt, method, submethod);
 336
 337         if (authctxt->postponed)
 338                 return;
 339
 340 #ifdef USE_PAM
 341         if (options.use_pam && authenticated) {
 342                 if (!PRIVSEP(do_pam_account())) {
 343                         /* if PAM returned a message, send it to the user */
 344                         if (buffer_len(&loginmsg) > 0) {
 345                                 buffer_append(&loginmsg, "\0", 1);
 346                                 userauth_send_banner(buffer_ptr(&loginmsg));
 347                                 packet_write_wait();
 348                         }
 349                         fatal("Access denied for user %s by PAM account "
 350                             "configuration", authctxt->user);
 351                 }
 352         }
 353 #endif
 354
 355 #ifdef _UNICOS
 356         if (authenticated && cray_access_denied(authctxt->user)) {
 357                 authenticated = 0;
 358                 fatal("Access denied for user %s.", authctxt->user);
 359         }
 360 #endif /* _UNICOS */
 361
 362         if (authenticated == 1) {
 363                 /* turn off userauth */
 364                 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
 365                 packet_start(SSH2_MSG_USERAUTH_SUCCESS);
 366                 packet_send();
 367                 packet_write_wait();
 368                 /* now we can break out */
 369                 authctxt->success = 1;
 370                 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
 371         } else {
 372
 373                 /* Allow initial try of "none" auth without failure penalty */
 374                 if (!partial && !authctxt->server_caused_failure &&
 375                     (authctxt->attempt > 1 || strcmp(method, "none") != 0))
 376                         authctxt->failures++;
 377                 if (authctxt->failures >= options.max_authtries) {
 378 #ifdef SSH_AUDIT_EVENTS
 379                         PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
 380 #endif
 381                         auth_maxtries_exceeded(authctxt);
 382                 }
 383                 methods = authmethods_get(authctxt);
 384                 debug3("%s: failure partial=%d next methods=\"%s\"", __func__,
 385                     partial, methods);
 386                 packet_start(SSH2_MSG_USERAUTH_FAILURE);
 387                 packet_put_cstring(methods);
 388                 packet_put_char(partial);
 389                 packet_send();
 390                 packet_write_wait();
 391                 free(methods);
 392         }
 393 }
 394
 395 /*
 396  * Checks whether method is allowed by at least one AuthenticationMethods
 397  * methods list. Returns 1 if allowed, or no methods lists configured.
 398  * 0 otherwise.
 399  */
 400 int
 401 auth2_method_allowed(Authctxt *authctxt, const char *method,
 402     const char *submethod)
 403 {
 404         u_int i;
 405
 406         /*
 407          * NB. authctxt->num_auth_methods might be zero as a result of
 408          * auth2_setup_methods_lists(), so check the configuration.
 409          */
 410         if (options.num_auth_methods == 0)
 411                 return 1;
 412         for (i = 0; i < authctxt->num_auth_methods; i++) {
 413                 if (list_starts_with(authctxt->auth_methods[i], method,
 414                     submethod) != MATCH_NONE)
 415                         return 1;
 416         }
 417         return 0;
 418 }
 419
 420 static char *
 421 authmethods_get(Authctxt *authctxt)
 422 {
 423         Buffer b;
 424         char *list;
 425         u_int i;
 426
 427         buffer_init(&b);
 428         for (i = 0; authmethods[i] != NULL; i++) {
 429                 if (strcmp(authmethods[i]->name, "none") == 0)
 430                         continue;
 431                 if (authmethods[i]->enabled == NULL ||
 432                     *(authmethods[i]->enabled) == 0)
 433                         continue;
 434                 if (!auth2_method_allowed(authctxt, authmethods[i]->name,
 435                     NULL))
 436                         continue;
 437                 if (buffer_len(&b) > 0)
 438                         buffer_append(&b, ",", 1);
 439                 buffer_append(&b, authmethods[i]->name,
 440                     strlen(authmethods[i]->name));
 441         }
 442         if ((list = sshbuf_dup_string(&b)) == NULL)
 443                 fatal("%s: sshbuf_dup_string failed", __func__);
 444         buffer_free(&b);
 445         return list;
 446 }
 447
 448 static Authmethod *
 449 authmethod_lookup(Authctxt *authctxt, const char *name)
 450 {
 451         int i;
 452
 453         if (name != NULL)
 454                 for (i = 0; authmethods[i] != NULL; i++)
 455                         if (authmethods[i]->enabled != NULL &&
 456                             *(authmethods[i]->enabled) != 0 &&
 457                             strcmp(name, authmethods[i]->name) == 0 &&
 458                             auth2_method_allowed(authctxt,
 459                             authmethods[i]->name, NULL))
 460                                 return authmethods[i];
 461         debug2("Unrecognized authentication method name: %s",
 462             name ? name : "NULL");
 463         return NULL;
 464 }
 465
 466 /*
 467  * Check a comma-separated list of methods for validity. Is need_enable is
 468  * non-zero, then also require that the methods are enabled.
 469  * Returns 0 on success or -1 if the methods list is invalid.
 470  */
 471 int
 472 auth2_methods_valid(const char *_methods, int need_enable)
 473 {
 474         char *methods, *omethods, *method, *p;
 475         u_int i, found;
 476         int ret = -1;
 477
 478         if (*_methods == '\0') {
 479                 error("empty authentication method list");
 480                 return -1;
 481         }
 482         omethods = methods = xstrdup(_methods);
 483         while ((method = strsep(&methods, ",")) != NULL) {
 484                 for (found = i = 0; !found && authmethods[i] != NULL; i++) {
 485                         if ((p = strchr(method, ':')) != NULL)
 486                                 *p = '\0';
 487                         if (strcmp(method, authmethods[i]->name) != 0)
 488                                 continue;
 489                         if (need_enable) {
 490                                 if (authmethods[i]->enabled == NULL ||
 491                                     *(authmethods[i]->enabled) == 0) {
 492                                         error("Disabled method \"%s\" in "
 493                                             "AuthenticationMethods list \"%s\"",
 494                                             method, _methods);
 495                                         goto out;
 496                                 }
 497                         }
 498                         found = 1;
 499                         break;
 500                 }
 501                 if (!found) {
 502                         error("Unknown authentication method \"%s\" in list",
 503                             method);
 504                         goto out;
 505                 }
 506         }
 507         ret = 0;
 508  out:
 509         free(omethods);
 510         return ret;
 511 }
 512
 513 /*
 514  * Prune the AuthenticationMethods supplied in the configuration, removing
 515  * any methods lists that include disabled methods. Note that this might
 516  * leave authctxt->num_auth_methods == 0, even when multiple required auth
 517  * has been requested. For this reason, all tests for whether multiple is
 518  * enabled should consult options.num_auth_methods directly.
 519  */
 520 int
 521 auth2_setup_methods_lists(Authctxt *authctxt)
 522 {
 523         u_int i;
 524
 525         if (options.num_auth_methods == 0)
 526                 return 0;
 527         debug3("%s: checking methods", __func__);
 528         authctxt->auth_methods = xcalloc(options.num_auth_methods,
 529             sizeof(*authctxt->auth_methods));
 530         authctxt->num_auth_methods = 0;
 531         for (i = 0; i < options.num_auth_methods; i++) {
 532                 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
 533                         logit("Authentication methods list \"%s\" contains "
 534                             "disabled method, skipping",
 535                             options.auth_methods[i]);
 536                         continue;
 537                 }
 538                 debug("authentication methods list %d: %s",
 539                     authctxt->num_auth_methods, options.auth_methods[i]);
 540                 authctxt->auth_methods[authctxt->num_auth_methods++] =
 541                     xstrdup(options.auth_methods[i]);
 542         }
 543         if (authctxt->num_auth_methods == 0) {
 544                 error("No AuthenticationMethods left after eliminating "
 545                     "disabled methods");
 546                 return -1;
 547         }
 548         return 0;
 549 }
 550
 551 static int
 552 list_starts_with(const char *methods, const char *method,
 553     const char *submethod)
 554 {
 555         size_t l = strlen(method);
 556         int match;
 557         const char *p;
 558
 559         if (strncmp(methods, method, l) != 0)
 560                 return MATCH_NONE;
 561         p = methods + l;
 562         match = MATCH_METHOD;
 563         if (*p == ':') {
 564                 if (!submethod)
 565                         return MATCH_PARTIAL;
 566                 l = strlen(submethod);
 567                 p += 1;
 568                 if (strncmp(submethod, p, l))
 569                         return MATCH_NONE;
 570                 p += l;
 571                 match = MATCH_BOTH;
 572         }
 573         if (*p != ',' && *p != '\0')
 574                 return MATCH_NONE;
 575         return match;
 576 }
 577
 578 /*
 579  * Remove method from the start of a comma-separated list of methods.
 580  * Returns 0 if the list of methods did not start with that method or 1
 581  * if it did.
 582  */
 583 static int
 584 remove_method(char **methods, const char *method, const char *submethod)
 585 {
 586         char *omethods = *methods, *p;
 587         size_t l = strlen(method);
 588         int match;
 589
 590         match = list_starts_with(omethods, method, submethod);
 591         if (match != MATCH_METHOD && match != MATCH_BOTH)
 592                 return 0;
 593         p = omethods + l;
 594         if (submethod && match == MATCH_BOTH)
 595                 p += 1 + strlen(submethod); /* include colon */
 596         if (*p == ',')
 597                 p++;
 598         *methods = xstrdup(p);
 599         free(omethods);
 600         return 1;
 601 }
 602
 603 /*
 604  * Called after successful authentication. Will remove the successful method
 605  * from the start of each list in which it occurs. If it was the last method
 606  * in any list, then authentication is deemed successful.
 607  * Returns 1 if the method completed any authentication list or 0 otherwise.
 608  */
 609 int
 610 auth2_update_methods_lists(Authctxt *authctxt, const char *method,
 611     const char *submethod)
 612 {
 613         u_int i, found = 0;
 614
 615         debug3("%s: updating methods list after \"%s\"", __func__, method);
 616         for (i = 0; i < authctxt->num_auth_methods; i++) {
 617                 if (!remove_method(&(authctxt->auth_methods[i]), method,
 618                     submethod))
 619                         continue;
 620                 found = 1;
 621                 if (*authctxt->auth_methods[i] == '\0') {
 622                         debug2("authentication methods list %d complete", i);
 623                         return 1;
 624                 }
 625                 debug3("authentication methods list %d remaining: \"%s\"",
 626                     i, authctxt->auth_methods[i]);
 627         }
 628         /* This should not happen, but would be bad if it did */
 629         if (!found)
 630                 fatal("%s: method not in AuthenticationMethods", __func__);
 631         return 0;
 632 }
 633
 634 /* Reset method-specific information */
 635 void auth2_authctxt_reset_info(Authctxt *authctxt)
 636 {
 637         sshkey_free(authctxt->auth_method_key);
 638         free(authctxt->auth_method_info);
 639         authctxt->auth_method_key = NULL;
 640         authctxt->auth_method_info = NULL;
 641 }
 642
 643 /* Record auth method-specific information for logs */
 644 void
 645 auth2_record_info(Authctxt *authctxt, const char *fmt, ...)
 646 {
 647         va_list ap;
 648         int i;
 649
 650         free(authctxt->auth_method_info);
 651         authctxt->auth_method_info = NULL;
 652
 653         va_start(ap, fmt);
 654         i = vasprintf(&authctxt->auth_method_info, fmt, ap);
 655         va_end(ap);
 656
 657         if (i < 0 || authctxt->auth_method_info == NULL)
 658                 fatal("%s: vasprintf failed", __func__);
 659 }
 660
 661 /*
 662  * Records a public key used in authentication. This is used for logging
 663  * and to ensure that the same key is not subsequently accepted again for
 664  * multiple authentication.
 665  */
 666 void
 667 auth2_record_key(Authctxt *authctxt, int authenticated,
 668     const struct sshkey *key)
 669 {
 670         struct sshkey **tmp, *dup;
 671         int r;
 672
 673         if ((r = sshkey_demote(key, &dup)) != 0)
 674                 fatal("%s: copy key: %s", __func__, ssh_err(r));
 675         sshkey_free(authctxt->auth_method_key);
 676         authctxt->auth_method_key = dup;
 677
 678         if (!authenticated)
 679                 return;
 680
 681         /* If authenticated, make sure we don't accept this key again */
 682         if ((r = sshkey_demote(key, &dup)) != 0)
 683                 fatal("%s: copy key: %s", __func__, ssh_err(r));
 684         if (authctxt->nprev_keys >= INT_MAX ||
 685             (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys,
 686             authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL)
 687                 fatal("%s: reallocarray failed", __func__);
 688         authctxt->prev_keys = tmp;
 689         authctxt->prev_keys[authctxt->nprev_keys] = dup;
 690         authctxt->nprev_keys++;
 691
 692 }
 693
 694 /* Checks whether a key has already been previously used for authentication */
 695 int
 696 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key)
 697 {
 698         u_int i;
 699         char *fp;
 700
 701         for (i = 0; i < authctxt->nprev_keys; i++) {
 702                 if (sshkey_equal_public(key, authctxt->prev_keys[i])) {
 703                         fp = sshkey_fingerprint(authctxt->prev_keys[i],
 704                             options.fingerprint_hash, SSH_FP_DEFAULT);
 705                         debug3("%s: key already used: %s %s", __func__,
 706                             sshkey_type(authctxt->prev_keys[i]),
 707                             fp == NULL ? "UNKNOWN" : fp);
 708                         free(fp);
 709                         return 1;
 710                 }
 711         }
 712         return 0;
 713 }
 714
 715 /*
 716  * Updates authctxt->session_info with details of authentication. Should be
 717  * whenever an authentication method succeeds.
 718  */
 719 void
 720 auth2_update_session_info(Authctxt *authctxt, const char *method,
 721     const char *submethod)
 722 {
 723         int r;
 724
 725         if (authctxt->session_info == NULL) {
 726                 if ((authctxt->session_info = sshbuf_new()) == NULL)
 727                         fatal("%s: sshbuf_new", __func__);
 728         }
 729
 730         /* Append method[/submethod] */
 731         if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s",
 732             method, submethod == NULL ? "" : "/",
 733             submethod == NULL ? "" : submethod)) != 0)
 734                 fatal("%s: append method: %s", __func__, ssh_err(r));
 735
 736         /* Append key if present */
 737         if (authctxt->auth_method_key != NULL) {
 738                 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
 739                     (r = sshkey_format_text(authctxt->auth_method_key,
 740                     authctxt->session_info)) != 0)
 741                         fatal("%s: append key: %s", __func__, ssh_err(r));
 742         }
 743
 744         if (authctxt->auth_method_info != NULL) {
 745                 /* Ensure no ambiguity here */
 746                 if (strchr(authctxt->auth_method_info, '\n') != NULL)
 747                         fatal("%s: auth_method_info contains \\n", __func__);
 748                 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
 749                     (r = sshbuf_putf(authctxt->session_info, "%s",
 750                     authctxt->auth_method_info)) != 0) {
 751                         fatal("%s: append method info: %s",
 752                             __func__, ssh_err(r));
 753                 }
 754         }
 755         if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0)
 756                 fatal("%s: append: %s", __func__, ssh_err(r));
 757 }
 758