crypto/openssh/sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.198 2013/06/05 12:52:38 dtucker Exp $ */
   2 /* $FreeBSD$ */
   3 /*
   4  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   5  * Copyright (c) 2008 Damien Miller.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 #include "includes.h"
  29
  30 #include <sys/types.h>
  31 #include <sys/socket.h>
  32 #include <sys/wait.h>
  33 #include <sys/stat.h>
  34
  35 #include <errno.h>
  36 #include <fcntl.h>
  37 #include <netdb.h>
  38 #include <pwd.h>
  39 #include <signal.h>
  40 #include <stdarg.h>
  41 #include <stdio.h>
  42 #include <string.h>
  43 #include <unistd.h>
  44 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS)
  45 #include <vis.h>
  46 #endif
  47
  48 #include "openbsd-compat/sys-queue.h"
  49
  50 #include "xmalloc.h"
  51 #include "ssh.h"
  52 #include "ssh2.h"
  53 #include "buffer.h"
  54 #include "packet.h"
  55 #include "compat.h"
  56 #include "cipher.h"
  57 #include "key.h"
  58 #include "kex.h"
  59 #include "myproposal.h"
  60 #include "sshconnect.h"
  61 #include "authfile.h"
  62 #include "dh.h"
  63 #include "authfd.h"
  64 #include "log.h"
  65 #include "readconf.h"
  66 #include "misc.h"
  67 #include "match.h"
  68 #include "dispatch.h"
  69 #include "canohost.h"
  70 #include "msg.h"
  71 #include "pathnames.h"
  72 #include "uidswap.h"
  73 #include "hostfile.h"
  74 #include "schnorr.h"
  75 #include "jpake.h"
  76
  77 #ifdef GSSAPI
  78 #include "ssh-gss.h"
  79 #endif
  80
  81 /* import */
  82 extern char *client_version_string;
  83 extern char *server_version_string;
  84 extern Options options;
  85 #ifdef  NONE_CIPHER_ENABLED
  86 extern Kex *xxx_kex;
  87
  88 /*
  89  * tty_flag is set in ssh.c so we can use it here.  If set then prevent
  90  * the switch to the null cipher.
  91  */
  92
  93 extern int tty_flag;
  94 #endif
  95
  96 /*
  97  * SSH2 key exchange
  98  */
  99
 100 u_char *session_id2 = NULL;
 101 u_int session_id2_len = 0;
 102
 103 char *xxx_host;
 104 struct sockaddr *xxx_hostaddr;
 105
 106 Kex *xxx_kex = NULL;
 107
 108 static int
 109 verify_host_key_callback(Key *hostkey)
 110 {
 111         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
 112                 fatal("Host key verification failed.");
 113         return 0;
 114 }
 115
 116 static char *
 117 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
 118 {
 119         char *oavail, *avail, *first, *last, *alg, *hostname, *ret;
 120         size_t maxlen;
 121         struct hostkeys *hostkeys;
 122         int ktype;
 123         u_int i;
 124
 125         /* Find all hostkeys for this hostname */
 126         get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
 127         hostkeys = init_hostkeys();
 128         for (i = 0; i < options.num_user_hostfiles; i++)
 129                 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]);
 130         for (i = 0; i < options.num_system_hostfiles; i++)
 131                 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]);
 132
 133         oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG);
 134         maxlen = strlen(avail) + 1;
 135         first = xmalloc(maxlen);
 136         last = xmalloc(maxlen);
 137         *first = *last = '\0';
 138
 139 #define ALG_APPEND(to, from) \
 140         do { \
 141                 if (*to != '\0') \
 142                         strlcat(to, ",", maxlen); \
 143                 strlcat(to, from, maxlen); \
 144         } while (0)
 145
 146         while ((alg = strsep(&avail, ",")) && *alg != '\0') {
 147                 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC)
 148                         fatal("%s: unknown alg %s", __func__, alg);
 149                 if (lookup_key_in_hostkeys_by_type(hostkeys,
 150                     key_type_plain(ktype), NULL))
 151                         ALG_APPEND(first, alg);
 152                 else
 153                         ALG_APPEND(last, alg);
 154         }
 155 #undef ALG_APPEND
 156         xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last);
 157         if (*first != '\0')
 158                 debug3("%s: prefer hostkeyalgs: %s", __func__, first);
 159
 160         free(first);
 161         free(last);
 162         free(hostname);
 163         free(oavail);
 164         free_hostkeys(hostkeys);
 165
 166         return ret;
 167 }
 168
 169 void
 170 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
 171 {
 172         Kex *kex;
 173
 174         xxx_host = host;
 175         xxx_hostaddr = hostaddr;
 176
 177         if (options.ciphers == (char *)-1) {
 178                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 179                 options.ciphers = NULL;
 180         }
 181         if (options.ciphers != NULL) {
 182                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 183                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 184         }
 185         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 186             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 187         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 188             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 189         if (options.compression) {
 190                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 191                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 192         } else {
 193                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 194                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 195         }
 196         if (options.macs != NULL) {
 197                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 198                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 199         }
 200         if (options.hostkeyalgorithms != NULL)
 201                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 202                     options.hostkeyalgorithms;
 203         else {
 204                 /* Prefer algorithms that we already have keys for */
 205                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 206                     order_hostkeyalgs(host, hostaddr, port);
 207         }
 208         if (options.kex_algorithms != NULL)
 209                 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
 210
 211         if (options.rekey_limit || options.rekey_interval)
 212                 packet_set_rekey_limits((u_int32_t)options.rekey_limit,
 213                     (time_t)options.rekey_interval);
 214
 215         /* start key exchange */
 216         kex = kex_setup(myproposal);
 217         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 218         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 219         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 220         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 221         kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
 222         kex->client_version_string=client_version_string;
 223         kex->server_version_string=server_version_string;
 224         kex->verify_host_key=&verify_host_key_callback;
 225
 226         xxx_kex = kex;
 227
 228         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 229
 230         if (options.use_roaming && !kex->roaming) {
 231                 debug("Roaming not allowed by server");
 232                 options.use_roaming = 0;
 233         }
 234
 235         session_id2 = kex->session_id;
 236         session_id2_len = kex->session_id_len;
 237
 238 #ifdef DEBUG_KEXDH
 239         /* send 1st encrypted/maced/compressed message */
 240         packet_start(SSH2_MSG_IGNORE);
 241         packet_put_cstring("markus");
 242         packet_send();
 243         packet_write_wait();
 244 #endif
 245 }
 246
 247 /*
 248  * Authenticate user
 249  */
 250
 251 typedef struct Authctxt Authctxt;
 252 typedef struct Authmethod Authmethod;
 253 typedef struct identity Identity;
 254 typedef struct idlist Idlist;
 255
 256 struct identity {
 257         TAILQ_ENTRY(identity) next;
 258         AuthenticationConnection *ac;   /* set if agent supports key */
 259         Key     *key;                   /* public/private key */
 260         char    *filename;              /* comment for agent-only keys */
 261         int     tried;
 262         int     isprivate;              /* key points to the private key */
 263         int     userprovided;
 264 };
 265 TAILQ_HEAD(idlist, identity);
 266
 267 struct Authctxt {
 268         const char *server_user;
 269         const char *local_user;
 270         const char *host;
 271         const char *service;
 272         Authmethod *method;
 273         sig_atomic_t success;
 274         char *authlist;
 275         /* pubkey */
 276         Idlist keys;
 277         AuthenticationConnection *agent;
 278         /* hostbased */
 279         Sensitive *sensitive;
 280         /* kbd-interactive */
 281         int info_req_seen;
 282         /* generic */
 283         void *methoddata;
 284 };
 285 struct Authmethod {
 286         char    *name;          /* string to compare against server's list */
 287         int     (*userauth)(Authctxt *authctxt);
 288         void    (*cleanup)(Authctxt *authctxt);
 289         int     *enabled;       /* flag in option struct that enables method */
 290         int     *batch_flag;    /* flag in option struct that disables method */
 291 };
 292
 293 void    input_userauth_success(int, u_int32_t, void *);
 294 void    input_userauth_success_unexpected(int, u_int32_t, void *);
 295 void    input_userauth_failure(int, u_int32_t, void *);
 296 void    input_userauth_banner(int, u_int32_t, void *);
 297 void    input_userauth_error(int, u_int32_t, void *);
 298 void    input_userauth_info_req(int, u_int32_t, void *);
 299 void    input_userauth_pk_ok(int, u_int32_t, void *);
 300 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 301 void    input_userauth_jpake_server_step1(int, u_int32_t, void *);
 302 void    input_userauth_jpake_server_step2(int, u_int32_t, void *);
 303 void    input_userauth_jpake_server_confirm(int, u_int32_t, void *);
 304
 305 int     userauth_none(Authctxt *);
 306 int     userauth_pubkey(Authctxt *);
 307 int     userauth_passwd(Authctxt *);
 308 int     userauth_kbdint(Authctxt *);
 309 int     userauth_hostbased(Authctxt *);
 310 int     userauth_jpake(Authctxt *);
 311
 312 void    userauth_jpake_cleanup(Authctxt *);
 313
 314 #ifdef GSSAPI
 315 int     userauth_gssapi(Authctxt *authctxt);
 316 void    input_gssapi_response(int type, u_int32_t, void *);
 317 void    input_gssapi_token(int type, u_int32_t, void *);
 318 void    input_gssapi_hash(int type, u_int32_t, void *);
 319 void    input_gssapi_error(int, u_int32_t, void *);
 320 void    input_gssapi_errtok(int, u_int32_t, void *);
 321 #endif
 322
 323 void    userauth(Authctxt *, char *);
 324
 325 static int sign_and_send_pubkey(Authctxt *, Identity *);
 326 static void pubkey_prepare(Authctxt *);
 327 static void pubkey_cleanup(Authctxt *);
 328 static Key *load_identity_file(char *, int);
 329
 330 static Authmethod *authmethod_get(char *authlist);
 331 static Authmethod *authmethod_lookup(const char *name);
 332 static char *authmethods_get(void);
 333
 334 Authmethod authmethods[] = {
 335 #ifdef GSSAPI
 336         {"gssapi-with-mic",
 337                 userauth_gssapi,
 338                 NULL,
 339                 &options.gss_authentication,
 340                 NULL},
 341 #endif
 342         {"hostbased",
 343                 userauth_hostbased,
 344                 NULL,
 345                 &options.hostbased_authentication,
 346                 NULL},
 347         {"publickey",
 348                 userauth_pubkey,
 349                 NULL,
 350                 &options.pubkey_authentication,
 351                 NULL},
 352 #ifdef JPAKE
 353         {"jpake-01@openssh.com",
 354                 userauth_jpake,
 355                 userauth_jpake_cleanup,
 356                 &options.zero_knowledge_password_authentication,
 357                 &options.batch_mode},
 358 #endif
 359         {"keyboard-interactive",
 360                 userauth_kbdint,
 361                 NULL,
 362                 &options.kbd_interactive_authentication,
 363                 &options.batch_mode},
 364         {"password",
 365                 userauth_passwd,
 366                 NULL,
 367                 &options.password_authentication,
 368                 &options.batch_mode},
 369         {"none",
 370                 userauth_none,
 371                 NULL,
 372                 NULL,
 373                 NULL},
 374         {NULL, NULL, NULL, NULL, NULL}
 375 };
 376
 377 void
 378 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 379     Sensitive *sensitive)
 380 {
 381         Authctxt authctxt;
 382         int type;
 383
 384         if (options.challenge_response_authentication)
 385                 options.kbd_interactive_authentication = 1;
 386
 387         packet_start(SSH2_MSG_SERVICE_REQUEST);
 388         packet_put_cstring("ssh-userauth");
 389         packet_send();
 390         debug("SSH2_MSG_SERVICE_REQUEST sent");
 391         packet_write_wait();
 392         type = packet_read();
 393         if (type != SSH2_MSG_SERVICE_ACCEPT)
 394                 fatal("Server denied authentication request: %d", type);
 395         if (packet_remaining() > 0) {
 396                 char *reply = packet_get_string(NULL);
 397                 debug2("service_accept: %s", reply);
 398                 free(reply);
 399         } else {
 400                 debug2("buggy server: service_accept w/o service");
 401         }
 402         packet_check_eom();
 403         debug("SSH2_MSG_SERVICE_ACCEPT received");
 404
 405         if (options.preferred_authentications == NULL)
 406                 options.preferred_authentications = authmethods_get();
 407
 408         /* setup authentication context */
 409         memset(&authctxt, 0, sizeof(authctxt));
 410         pubkey_prepare(&authctxt);
 411         authctxt.server_user = server_user;
 412         authctxt.local_user = local_user;
 413         authctxt.host = host;
 414         authctxt.service = "ssh-connection";            /* service name */
 415         authctxt.success = 0;
 416         authctxt.method = authmethod_lookup("none");
 417         authctxt.authlist = NULL;
 418         authctxt.methoddata = NULL;
 419         authctxt.sensitive = sensitive;
 420         authctxt.info_req_seen = 0;
 421         if (authctxt.method == NULL)
 422                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 423
 424         /* initial userauth request */
 425         userauth_none(&authctxt);
 426
 427         dispatch_init(&input_userauth_error);
 428         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 429         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 430         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 431         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 432
 433         pubkey_cleanup(&authctxt);
 434         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 435
 436 #ifdef  NONE_CIPHER_ENABLED
 437         /*
 438          * If the user explicitly requests to use the none cipher enable it
 439          * post authentication and only if the right conditions are met: both
 440          * of the NONE switches must be true and there must be no tty allocated.
 441          */
 442         if (options.none_switch == 1 && options.none_enabled == 1) {
 443                 if (!tty_flag) {
 444                         debug("Requesting none cipher re-keying...");
 445                         myproposal[PROPOSAL_ENC_ALGS_STOC] = "none";
 446                         myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none";
 447                         kex_prop2buf(&xxx_kex->my, myproposal);
 448                         packet_request_rekeying();
 449                         fprintf(stderr, "WARNING: enabled NONE cipher\n");
 450                 } else {
 451                         /* Requested NONE cipher on an interactive session. */
 452                         debug("Cannot switch to NONE cipher with tty "
 453                             "allocated");
 454                         fprintf(stderr, "NONE cipher switch disabled given "
 455                             "a TTY is allocated\n");
 456                 }
 457         }
 458 #endif
 459         debug("Authentication succeeded (%s).", authctxt.method->name);
 460 }
 461
 462 void
 463 userauth(Authctxt *authctxt, char *authlist)
 464 {
 465         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 466                 authctxt->method->cleanup(authctxt);
 467
 468         free(authctxt->methoddata);
 469         authctxt->methoddata = NULL;
 470         if (authlist == NULL) {
 471                 authlist = authctxt->authlist;
 472         } else {
 473                 free(authctxt->authlist);
 474                 authctxt->authlist = authlist;
 475         }
 476         for (;;) {
 477                 Authmethod *method = authmethod_get(authlist);
 478                 if (method == NULL)
 479                         fatal("Permission denied (%s).", authlist);
 480                 authctxt->method = method;
 481
 482                 /* reset the per method handler */
 483                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 484                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 485
 486                 /* and try new method */
 487                 if (method->userauth(authctxt) != 0) {
 488                         debug2("we sent a %s packet, wait for reply", method->name);
 489                         break;
 490                 } else {
 491                         debug2("we did not send a packet, disable method");
 492                         method->enabled = NULL;
 493                 }
 494         }
 495 }
 496
 497 /* ARGSUSED */
 498 void
 499 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 500 {
 501         fatal("input_userauth_error: bad message during authentication: "
 502             "type %d", type);
 503 }
 504
 505 /* ARGSUSED */
 506 void
 507 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 508 {
 509         char *msg, *raw, *lang;
 510         u_int len;
 511
 512         debug3("input_userauth_banner");
 513         raw = packet_get_string(&len);
 514         lang = packet_get_string(NULL);
 515         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
 516                 if (len > 65536)
 517                         len = 65536;
 518                 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
 519                 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH);
 520                 fprintf(stderr, "%s", msg);
 521                 free(msg);
 522         }
 523         free(raw);
 524         free(lang);
 525 }
 526
 527 /* ARGSUSED */
 528 void
 529 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 530 {
 531         Authctxt *authctxt = ctxt;
 532
 533         if (authctxt == NULL)
 534                 fatal("input_userauth_success: no authentication context");
 535         free(authctxt->authlist);
 536         authctxt->authlist = NULL;
 537         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 538                 authctxt->method->cleanup(authctxt);
 539         free(authctxt->methoddata);
 540         authctxt->methoddata = NULL;
 541         authctxt->success = 1;                  /* break out */
 542 }
 543
 544 void
 545 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
 546 {
 547         Authctxt *authctxt = ctxt;
 548
 549         if (authctxt == NULL)
 550                 fatal("%s: no authentication context", __func__);
 551
 552         fatal("Unexpected authentication success during %s.",
 553             authctxt->method->name);
 554 }
 555
 556 /* ARGSUSED */
 557 void
 558 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 559 {
 560         Authctxt *authctxt = ctxt;
 561         char *authlist = NULL;
 562         int partial;
 563
 564         if (authctxt == NULL)
 565                 fatal("input_userauth_failure: no authentication context");
 566
 567         authlist = packet_get_string(NULL);
 568         partial = packet_get_char();
 569         packet_check_eom();
 570
 571         if (partial != 0) {
 572                 logit("Authenticated with partial success.");
 573                 /* reset state */
 574                 pubkey_cleanup(authctxt);
 575                 pubkey_prepare(authctxt);
 576         }
 577         debug("Authentications that can continue: %s", authlist);
 578
 579         userauth(authctxt, authlist);
 580 }
 581
 582 /* ARGSUSED */
 583 void
 584 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 585 {
 586         Authctxt *authctxt = ctxt;
 587         Key *key = NULL;
 588         Identity *id = NULL;
 589         Buffer b;
 590         int pktype, sent = 0;
 591         u_int alen, blen;
 592         char *pkalg, *fp;
 593         u_char *pkblob;
 594
 595         if (authctxt == NULL)
 596                 fatal("input_userauth_pk_ok: no authentication context");
 597         if (datafellows & SSH_BUG_PKOK) {
 598                 /* this is similar to SSH_BUG_PKAUTH */
 599                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 600                 pkblob = packet_get_string(&blen);
 601                 buffer_init(&b);
 602                 buffer_append(&b, pkblob, blen);
 603                 pkalg = buffer_get_string(&b, &alen);
 604                 buffer_free(&b);
 605         } else {
 606                 pkalg = packet_get_string(&alen);
 607                 pkblob = packet_get_string(&blen);
 608         }
 609         packet_check_eom();
 610
 611         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 612
 613         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 614                 debug("unknown pkalg %s", pkalg);
 615                 goto done;
 616         }
 617         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 618                 debug("no key from blob. pkalg %s", pkalg);
 619                 goto done;
 620         }
 621         if (key->type != pktype) {
 622                 error("input_userauth_pk_ok: type mismatch "
 623                     "for decoded key (received %d, expected %d)",
 624                     key->type, pktype);
 625                 goto done;
 626         }
 627         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 628         debug2("input_userauth_pk_ok: fp %s", fp);
 629         free(fp);
 630
 631         /*
 632          * search keys in the reverse order, because last candidate has been
 633          * moved to the end of the queue.  this also avoids confusion by
 634          * duplicate keys
 635          */
 636         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 637                 if (key_equal(key, id->key)) {
 638                         sent = sign_and_send_pubkey(authctxt, id);
 639                         break;
 640                 }
 641         }
 642 done:
 643         if (key != NULL)
 644                 key_free(key);
 645         free(pkalg);
 646         free(pkblob);
 647
 648         /* try another method if we did not send a packet */
 649         if (sent == 0)
 650                 userauth(authctxt, NULL);
 651 }
 652
 653 #ifdef GSSAPI
 654 int
 655 userauth_gssapi(Authctxt *authctxt)
 656 {
 657         Gssctxt *gssctxt = NULL;
 658         static gss_OID_set gss_supported = NULL;
 659         static u_int mech = 0;
 660         OM_uint32 min;
 661         int ok = 0;
 662
 663         /* Try one GSSAPI method at a time, rather than sending them all at
 664          * once. */
 665
 666         if (gss_supported == NULL)
 667                 gss_indicate_mechs(&min, &gss_supported);
 668
 669         /* Check to see if the mechanism is usable before we offer it */
 670         while (mech < gss_supported->count && !ok) {
 671                 /* My DER encoding requires length<128 */
 672                 if (gss_supported->elements[mech].length < 128 &&
 673                     ssh_gssapi_check_mechanism(&gssctxt,
 674                     &gss_supported->elements[mech], authctxt->host)) {
 675                         ok = 1; /* Mechanism works */
 676                 } else {
 677                         mech++;
 678                 }
 679         }
 680
 681         if (!ok)
 682                 return 0;
 683
 684         authctxt->methoddata=(void *)gssctxt;
 685
 686         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 687         packet_put_cstring(authctxt->server_user);
 688         packet_put_cstring(authctxt->service);
 689         packet_put_cstring(authctxt->method->name);
 690
 691         packet_put_int(1);
 692
 693         packet_put_int((gss_supported->elements[mech].length) + 2);
 694         packet_put_char(SSH_GSS_OIDTYPE);
 695         packet_put_char(gss_supported->elements[mech].length);
 696         packet_put_raw(gss_supported->elements[mech].elements,
 697             gss_supported->elements[mech].length);
 698
 699         packet_send();
 700
 701         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 702         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 703         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 704         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 705
 706         mech++; /* Move along to next candidate */
 707
 708         return 1;
 709 }
 710
 711 static OM_uint32
 712 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 713 {
 714         Authctxt *authctxt = ctxt;
 715         Gssctxt *gssctxt = authctxt->methoddata;
 716         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 717         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 718         gss_buffer_desc gssbuf;
 719         OM_uint32 status, ms, flags;
 720         Buffer b;
 721
 722         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 723             recv_tok, &send_tok, &flags);
 724
 725         if (send_tok.length > 0) {
 726                 if (GSS_ERROR(status))
 727                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 728                 else
 729                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 730
 731                 packet_put_string(send_tok.value, send_tok.length);
 732                 packet_send();
 733                 gss_release_buffer(&ms, &send_tok);
 734         }
 735
 736         if (status == GSS_S_COMPLETE) {
 737                 /* send either complete or MIC, depending on mechanism */
 738                 if (!(flags & GSS_C_INTEG_FLAG)) {
 739                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 740                         packet_send();
 741                 } else {
 742                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 743                             authctxt->service, "gssapi-with-mic");
 744
 745                         gssbuf.value = buffer_ptr(&b);
 746                         gssbuf.length = buffer_len(&b);
 747
 748                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 749
 750                         if (!GSS_ERROR(status)) {
 751                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 752                                 packet_put_string(mic.value, mic.length);
 753
 754                                 packet_send();
 755                         }
 756
 757                         buffer_free(&b);
 758                         gss_release_buffer(&ms, &mic);
 759                 }
 760         }
 761
 762         return status;
 763 }
 764
 765 /* ARGSUSED */
 766 void
 767 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 768 {
 769         Authctxt *authctxt = ctxt;
 770         Gssctxt *gssctxt;
 771         int oidlen;
 772         char *oidv;
 773
 774         if (authctxt == NULL)
 775                 fatal("input_gssapi_response: no authentication context");
 776         gssctxt = authctxt->methoddata;
 777
 778         /* Setup our OID */
 779         oidv = packet_get_string(&oidlen);
 780
 781         if (oidlen <= 2 ||
 782             oidv[0] != SSH_GSS_OIDTYPE ||
 783             oidv[1] != oidlen - 2) {
 784                 free(oidv);
 785                 debug("Badly encoded mechanism OID received");
 786                 userauth(authctxt, NULL);
 787                 return;
 788         }
 789
 790         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 791                 fatal("Server returned different OID than expected");
 792
 793         packet_check_eom();
 794
 795         free(oidv);
 796
 797         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 798                 /* Start again with next method on list */
 799                 debug("Trying to start again");
 800                 userauth(authctxt, NULL);
 801                 return;
 802         }
 803 }
 804
 805 /* ARGSUSED */
 806 void
 807 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 808 {
 809         Authctxt *authctxt = ctxt;
 810         gss_buffer_desc recv_tok;
 811         OM_uint32 status;
 812         u_int slen;
 813
 814         if (authctxt == NULL)
 815                 fatal("input_gssapi_response: no authentication context");
 816
 817         recv_tok.value = packet_get_string(&slen);
 818         recv_tok.length = slen; /* safe typecast */
 819
 820         packet_check_eom();
 821
 822         status = process_gssapi_token(ctxt, &recv_tok);
 823
 824         free(recv_tok.value);
 825
 826         if (GSS_ERROR(status)) {
 827                 /* Start again with the next method in the list */
 828                 userauth(authctxt, NULL);
 829                 return;
 830         }
 831 }
 832
 833 /* ARGSUSED */
 834 void
 835 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 836 {
 837         Authctxt *authctxt = ctxt;
 838         Gssctxt *gssctxt;
 839         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 840         gss_buffer_desc recv_tok;
 841         OM_uint32 ms;
 842         u_int len;
 843
 844         if (authctxt == NULL)
 845                 fatal("input_gssapi_response: no authentication context");
 846         gssctxt = authctxt->methoddata;
 847
 848         recv_tok.value = packet_get_string(&len);
 849         recv_tok.length = len;
 850
 851         packet_check_eom();
 852
 853         /* Stick it into GSSAPI and see what it says */
 854         (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 855             &recv_tok, &send_tok, NULL);
 856
 857         free(recv_tok.value);
 858         gss_release_buffer(&ms, &send_tok);
 859
 860         /* Server will be returning a failed packet after this one */
 861 }
 862
 863 /* ARGSUSED */
 864 void
 865 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 866 {
 867         char *msg;
 868         char *lang;
 869
 870         /* maj */(void)packet_get_int();
 871         /* min */(void)packet_get_int();
 872         msg=packet_get_string(NULL);
 873         lang=packet_get_string(NULL);
 874
 875         packet_check_eom();
 876
 877         debug("Server GSSAPI Error:\n%s", msg);
 878         free(msg);
 879         free(lang);
 880 }
 881 #endif /* GSSAPI */
 882
 883 int
 884 userauth_none(Authctxt *authctxt)
 885 {
 886         /* initial userauth request */
 887         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 888         packet_put_cstring(authctxt->server_user);
 889         packet_put_cstring(authctxt->service);
 890         packet_put_cstring(authctxt->method->name);
 891         packet_send();
 892         return 1;
 893 }
 894
 895 int
 896 userauth_passwd(Authctxt *authctxt)
 897 {
 898         static int attempt = 0;
 899         char prompt[150];
 900         char *password;
 901         const char *host = options.host_key_alias ?  options.host_key_alias :
 902             authctxt->host;
 903
 904         if (attempt++ >= options.number_of_password_prompts)
 905                 return 0;
 906
 907         if (attempt != 1)
 908                 error("Permission denied, please try again.");
 909
 910         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 911             authctxt->server_user, host);
 912         password = read_passphrase(prompt, 0);
 913         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 914         packet_put_cstring(authctxt->server_user);
 915         packet_put_cstring(authctxt->service);
 916         packet_put_cstring(authctxt->method->name);
 917         packet_put_char(0);
 918         packet_put_cstring(password);
 919         memset(password, 0, strlen(password));
 920         free(password);
 921         packet_add_padding(64);
 922         packet_send();
 923
 924         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 925             &input_userauth_passwd_changereq);
 926
 927         return 1;
 928 }
 929
 930 /*
 931  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 932  */
 933 /* ARGSUSED */
 934 void
 935 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 936 {
 937         Authctxt *authctxt = ctxt;
 938         char *info, *lang, *password = NULL, *retype = NULL;
 939         char prompt[150];
 940         const char *host = options.host_key_alias ? options.host_key_alias :
 941             authctxt->host;
 942
 943         debug2("input_userauth_passwd_changereq");
 944
 945         if (authctxt == NULL)
 946                 fatal("input_userauth_passwd_changereq: "
 947                     "no authentication context");
 948
 949         info = packet_get_string(NULL);
 950         lang = packet_get_string(NULL);
 951         if (strlen(info) > 0)
 952                 logit("%s", info);
 953         free(info);
 954         free(lang);
 955         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 956         packet_put_cstring(authctxt->server_user);
 957         packet_put_cstring(authctxt->service);
 958         packet_put_cstring(authctxt->method->name);
 959         packet_put_char(1);                     /* additional info */
 960         snprintf(prompt, sizeof(prompt),
 961             "Enter %.30s@%.128s's old password: ",
 962             authctxt->server_user, host);
 963         password = read_passphrase(prompt, 0);
 964         packet_put_cstring(password);
 965         memset(password, 0, strlen(password));
 966         free(password);
 967         password = NULL;
 968         while (password == NULL) {
 969                 snprintf(prompt, sizeof(prompt),
 970                     "Enter %.30s@%.128s's new password: ",
 971                     authctxt->server_user, host);
 972                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 973                 if (password == NULL) {
 974                         /* bail out */
 975                         return;
 976                 }
 977                 snprintf(prompt, sizeof(prompt),
 978                     "Retype %.30s@%.128s's new password: ",
 979                     authctxt->server_user, host);
 980                 retype = read_passphrase(prompt, 0);
 981                 if (strcmp(password, retype) != 0) {
 982                         memset(password, 0, strlen(password));
 983                         free(password);
 984                         logit("Mismatch; try again, EOF to quit.");
 985                         password = NULL;
 986                 }
 987                 memset(retype, 0, strlen(retype));
 988                 free(retype);
 989         }
 990         packet_put_cstring(password);
 991         memset(password, 0, strlen(password));
 992         free(password);
 993         packet_add_padding(64);
 994         packet_send();
 995
 996         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 997             &input_userauth_passwd_changereq);
 998 }
 999
1000 #ifdef JPAKE
1001 static char *
1002 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt)
1003 {
1004         /* OpenBSD crypt(3) handles all of these */
1005         if (strcmp(crypt_scheme, "crypt") == 0 ||
1006             strcmp(crypt_scheme, "bcrypt") == 0 ||
1007             strcmp(crypt_scheme, "md5crypt") == 0 ||
1008             strcmp(crypt_scheme, "crypt-extended") == 0)
1009                 return xstrdup(crypt(password, salt));
1010         error("%s: unsupported password encryption scheme \"%.100s\"",
1011             __func__, crypt_scheme);
1012         return NULL;
1013 }
1014
1015 static BIGNUM *
1016 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme,
1017     const char *salt)
1018 {
1019         char prompt[256], *password, *crypted;
1020         u_char *secret;
1021         u_int secret_len;
1022         BIGNUM *ret;
1023
1024         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ",
1025             authctxt->server_user, authctxt->host);
1026         password = read_passphrase(prompt, 0);
1027
1028         if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) {
1029                 logit("Disabling %s authentication", authctxt->method->name);
1030                 authctxt->method->enabled = NULL;
1031                 /* Continue with an empty password to fail gracefully */
1032                 crypted = xstrdup("");
1033         }
1034
1035 #ifdef JPAKE_DEBUG
1036         debug3("%s: salt = %s", __func__, salt);
1037         debug3("%s: scheme = %s", __func__, crypt_scheme);
1038         debug3("%s: crypted = %s", __func__, crypted);
1039 #endif
1040
1041         if (hash_buffer(crypted, strlen(crypted), EVP_sha256(),
1042             &secret, &secret_len) != 0)
1043                 fatal("%s: hash_buffer", __func__);
1044
1045         bzero(password, strlen(password));
1046         bzero(crypted, strlen(crypted));
1047         free(password);
1048         free(crypted);
1049
1050         if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL)
1051                 fatal("%s: BN_bin2bn (secret)", __func__);
1052         bzero(secret, secret_len);
1053         free(secret);
1054
1055         return ret;
1056 }
1057
1058 /* ARGSUSED */
1059 void
1060 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt)
1061 {
1062         Authctxt *authctxt = ctxt;
1063         struct jpake_ctx *pctx = authctxt->methoddata;
1064         u_char *x3_proof, *x4_proof, *x2_s_proof;
1065         u_int x3_proof_len, x4_proof_len, x2_s_proof_len;
1066         char *crypt_scheme, *salt;
1067
1068         /* Disable this message */
1069         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL);
1070
1071         if ((pctx->g_x3 = BN_new()) == NULL ||
1072             (pctx->g_x4 = BN_new()) == NULL)
1073                 fatal("%s: BN_new", __func__);
1074
1075         /* Fetch step 1 values */
1076         crypt_scheme = packet_get_string(NULL);
1077         salt = packet_get_string(NULL);
1078         pctx->server_id = packet_get_string(&pctx->server_id_len);
1079         packet_get_bignum2(pctx->g_x3);
1080         packet_get_bignum2(pctx->g_x4);
1081         x3_proof = packet_get_string(&x3_proof_len);
1082         x4_proof = packet_get_string(&x4_proof_len);
1083         packet_check_eom();
1084
1085         JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__));
1086
1087         /* Obtain password and derive secret */
1088         pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt);
1089         bzero(crypt_scheme, strlen(crypt_scheme));
1090         bzero(salt, strlen(salt));
1091         free(crypt_scheme);
1092         free(salt);
1093         JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__));
1094
1095         /* Calculate step 2 values */
1096         jpake_step2(pctx->grp, pctx->s, pctx->g_x1,
1097             pctx->g_x3, pctx->g_x4, pctx->x2,
1098             pctx->server_id, pctx->server_id_len,
1099             pctx->client_id, pctx->client_id_len,
1100             x3_proof, x3_proof_len,
1101             x4_proof, x4_proof_len,
1102             &pctx->a,
1103             &x2_s_proof, &x2_s_proof_len);
1104
1105         bzero(x3_proof, x3_proof_len);
1106         bzero(x4_proof, x4_proof_len);
1107         free(x3_proof);
1108         free(x4_proof);
1109
1110         JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__));
1111
1112         /* Send values for step 2 */
1113         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2);
1114         packet_put_bignum2(pctx->a);
1115         packet_put_string(x2_s_proof, x2_s_proof_len);
1116         packet_send();
1117
1118         bzero(x2_s_proof, x2_s_proof_len);
1119         free(x2_s_proof);
1120
1121         /* Expect step 2 packet from peer */
1122         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2,
1123             input_userauth_jpake_server_step2);
1124 }
1125
1126 /* ARGSUSED */
1127 void
1128 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt)
1129 {
1130         Authctxt *authctxt = ctxt;
1131         struct jpake_ctx *pctx = authctxt->methoddata;
1132         u_char *x4_s_proof;
1133         u_int x4_s_proof_len;
1134
1135         /* Disable this message */
1136         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL);
1137
1138         if ((pctx->b = BN_new()) == NULL)
1139                 fatal("%s: BN_new", __func__);
1140
1141         /* Fetch step 2 values */
1142         packet_get_bignum2(pctx->b);
1143         x4_s_proof = packet_get_string(&x4_s_proof_len);
1144         packet_check_eom();
1145
1146         JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__));
1147
1148         /* Derive shared key and calculate confirmation hash */
1149         jpake_key_confirm(pctx->grp, pctx->s, pctx->b,
1150             pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4,
1151             pctx->client_id, pctx->client_id_len,
1152             pctx->server_id, pctx->server_id_len,
1153             session_id2, session_id2_len,
1154             x4_s_proof, x4_s_proof_len,
1155             &pctx->k,
1156             &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len);
1157
1158         bzero(x4_s_proof, x4_s_proof_len);
1159         free(x4_s_proof);
1160
1161         JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__));
1162
1163         /* Send key confirmation proof */
1164         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM);
1165         packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len);
1166         packet_send();
1167
1168         /* Expect confirmation from peer */
1169         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM,
1170             input_userauth_jpake_server_confirm);
1171 }
1172
1173 /* ARGSUSED */
1174 void
1175 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt)
1176 {
1177         Authctxt *authctxt = ctxt;
1178         struct jpake_ctx *pctx = authctxt->methoddata;
1179
1180         /* Disable this message */
1181         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL);
1182
1183         pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len);
1184         packet_check_eom();
1185
1186         JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__));
1187
1188         /* Verify expected confirmation hash */
1189         if (jpake_check_confirm(pctx->k,
1190             pctx->server_id, pctx->server_id_len,
1191             session_id2, session_id2_len,
1192             pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1)
1193                 debug("%s: %s success", __func__, authctxt->method->name);
1194         else {
1195                 debug("%s: confirmation mismatch", __func__);
1196                 /* XXX stash this so if auth succeeds then we can warn/kill */
1197         }
1198
1199         userauth_jpake_cleanup(authctxt);
1200 }
1201 #endif /* JPAKE */
1202
1203 static int
1204 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
1205     u_char *data, u_int datalen)
1206 {
1207         Key *prv;
1208         int ret;
1209
1210         /* the agent supports this key */
1211         if (id->ac)
1212                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1213                     data, datalen));
1214         /*
1215          * we have already loaded the private key or
1216          * the private key is stored in external hardware
1217          */
1218         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1219                 return (key_sign(id->key, sigp, lenp, data, datalen));
1220         /* load the private key from the file */
1221         if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL)
1222                 return (-1);
1223         ret = key_sign(prv, sigp, lenp, data, datalen);
1224         key_free(prv);
1225         return (ret);
1226 }
1227
1228 static int
1229 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1230 {
1231         Buffer b;
1232         u_char *blob, *signature;
1233         u_int bloblen, slen;
1234         u_int skip = 0;
1235         int ret = -1;
1236         int have_sig = 1;
1237         char *fp;
1238
1239         fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
1240         debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp);
1241         free(fp);
1242
1243         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1244                 /* we cannot handle this key */
1245                 debug3("sign_and_send_pubkey: cannot handle key");
1246                 return 0;
1247         }
1248         /* data to be signed */
1249         buffer_init(&b);
1250         if (datafellows & SSH_OLD_SESSIONID) {
1251                 buffer_append(&b, session_id2, session_id2_len);
1252                 skip = session_id2_len;
1253         } else {
1254                 buffer_put_string(&b, session_id2, session_id2_len);
1255                 skip = buffer_len(&b);
1256         }
1257         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1258         buffer_put_cstring(&b, authctxt->server_user);
1259         buffer_put_cstring(&b,
1260             datafellows & SSH_BUG_PKSERVICE ?
1261             "ssh-userauth" :
1262             authctxt->service);
1263         if (datafellows & SSH_BUG_PKAUTH) {
1264                 buffer_put_char(&b, have_sig);
1265         } else {
1266                 buffer_put_cstring(&b, authctxt->method->name);
1267                 buffer_put_char(&b, have_sig);
1268                 buffer_put_cstring(&b, key_ssh_name(id->key));
1269         }
1270         buffer_put_string(&b, blob, bloblen);
1271
1272         /* generate signature */
1273         ret = identity_sign(id, &signature, &slen,
1274             buffer_ptr(&b), buffer_len(&b));
1275         if (ret == -1) {
1276                 free(blob);
1277                 buffer_free(&b);
1278                 return 0;
1279         }
1280 #ifdef DEBUG_PK
1281         buffer_dump(&b);
1282 #endif
1283         if (datafellows & SSH_BUG_PKSERVICE) {
1284                 buffer_clear(&b);
1285                 buffer_append(&b, session_id2, session_id2_len);
1286                 skip = session_id2_len;
1287                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1288                 buffer_put_cstring(&b, authctxt->server_user);
1289                 buffer_put_cstring(&b, authctxt->service);
1290                 buffer_put_cstring(&b, authctxt->method->name);
1291                 buffer_put_char(&b, have_sig);
1292                 if (!(datafellows & SSH_BUG_PKAUTH))
1293                         buffer_put_cstring(&b, key_ssh_name(id->key));
1294                 buffer_put_string(&b, blob, bloblen);
1295         }
1296         free(blob);
1297
1298         /* append signature */
1299         buffer_put_string(&b, signature, slen);
1300         free(signature);
1301
1302         /* skip session id and packet type */
1303         if (buffer_len(&b) < skip + 1)
1304                 fatal("userauth_pubkey: internal error");
1305         buffer_consume(&b, skip + 1);
1306
1307         /* put remaining data from buffer into packet */
1308         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1309         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1310         buffer_free(&b);
1311         packet_send();
1312
1313         return 1;
1314 }
1315
1316 static int
1317 send_pubkey_test(Authctxt *authctxt, Identity *id)
1318 {
1319         u_char *blob;
1320         u_int bloblen, have_sig = 0;
1321
1322         debug3("send_pubkey_test");
1323
1324         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1325                 /* we cannot handle this key */
1326                 debug3("send_pubkey_test: cannot handle key");
1327                 return 0;
1328         }
1329         /* register callback for USERAUTH_PK_OK message */
1330         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1331
1332         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1333         packet_put_cstring(authctxt->server_user);
1334         packet_put_cstring(authctxt->service);
1335         packet_put_cstring(authctxt->method->name);
1336         packet_put_char(have_sig);
1337         if (!(datafellows & SSH_BUG_PKAUTH))
1338                 packet_put_cstring(key_ssh_name(id->key));
1339         packet_put_string(blob, bloblen);
1340         free(blob);
1341         packet_send();
1342         return 1;
1343 }
1344
1345 static Key *
1346 load_identity_file(char *filename, int userprovided)
1347 {
1348         Key *private;
1349         char prompt[300], *passphrase;
1350         int perm_ok = 0, quit, i;
1351         struct stat st;
1352
1353         if (stat(filename, &st) < 0) {
1354                 (userprovided ? logit : debug3)("no such identity: %s: %s",
1355                     filename, strerror(errno));
1356                 return NULL;
1357         }
1358         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1359         if (!perm_ok) {
1360                 if (private != NULL)
1361                         key_free(private);
1362                 return NULL;
1363         }
1364         if (private == NULL) {
1365                 if (options.batch_mode)
1366                         return NULL;
1367                 snprintf(prompt, sizeof prompt,
1368                     "Enter passphrase for key '%.100s': ", filename);
1369                 for (i = 0; i < options.number_of_password_prompts; i++) {
1370                         passphrase = read_passphrase(prompt, 0);
1371                         if (strcmp(passphrase, "") != 0) {
1372                                 private = key_load_private_type(KEY_UNSPEC,
1373                                     filename, passphrase, NULL, NULL);
1374                                 quit = 0;
1375                         } else {
1376                                 debug2("no passphrase given, try next key");
1377                                 quit = 1;
1378                         }
1379                         memset(passphrase, 0, strlen(passphrase));
1380                         free(passphrase);
1381                         if (private != NULL || quit)
1382                                 break;
1383                         debug2("bad passphrase given, try again...");
1384                 }
1385         }
1386         return private;
1387 }
1388
1389 /*
1390  * try keys in the following order:
1391  *      1. agent keys that are found in the config file
1392  *      2. other agent keys
1393  *      3. keys that are only listed in the config file
1394  */
1395 static void
1396 pubkey_prepare(Authctxt *authctxt)
1397 {
1398         Identity *id, *id2, *tmp;
1399         Idlist agent, files, *preferred;
1400         Key *key;
1401         AuthenticationConnection *ac;
1402         char *comment;
1403         int i, found;
1404
1405         TAILQ_INIT(&agent);     /* keys from the agent */
1406         TAILQ_INIT(&files);     /* keys from the config file */
1407         preferred = &authctxt->keys;
1408         TAILQ_INIT(preferred);  /* preferred order of keys */
1409
1410         /* list of keys stored in the filesystem and PKCS#11 */
1411         for (i = 0; i < options.num_identity_files; i++) {
1412                 key = options.identity_keys[i];
1413                 if (key && key->type == KEY_RSA1)
1414                         continue;
1415                 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1416                         continue;
1417                 options.identity_keys[i] = NULL;
1418                 id = xcalloc(1, sizeof(*id));
1419                 id->key = key;
1420                 id->filename = xstrdup(options.identity_files[i]);
1421                 id->userprovided = options.identity_file_userprovided[i];
1422                 TAILQ_INSERT_TAIL(&files, id, next);
1423         }
1424         /* Prefer PKCS11 keys that are explicitly listed */
1425         TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1426                 if (id->key == NULL || (id->key->flags & KEY_FLAG_EXT) == 0)
1427                         continue;
1428                 found = 0;
1429                 TAILQ_FOREACH(id2, &files, next) {
1430                         if (id2->key == NULL ||
1431                             (id2->key->flags & KEY_FLAG_EXT) != 0)
1432                                 continue;
1433                         if (key_equal(id->key, id2->key)) {
1434                                 TAILQ_REMOVE(&files, id, next);
1435                                 TAILQ_INSERT_TAIL(preferred, id, next);
1436                                 found = 1;
1437                                 break;
1438                         }
1439                 }
1440                 /* If IdentitiesOnly set and key not found then don't use it */
1441                 if (!found && options.identities_only) {
1442                         TAILQ_REMOVE(&files, id, next);
1443                         bzero(id, sizeof(*id));
1444                         free(id);
1445                 }
1446         }
1447         /* list of keys supported by the agent */
1448         if ((ac = ssh_get_authentication_connection())) {
1449                 for (key = ssh_get_first_identity(ac, &comment, 2);
1450                     key != NULL;
1451                     key = ssh_get_next_identity(ac, &comment, 2)) {
1452                         found = 0;
1453                         TAILQ_FOREACH(id, &files, next) {
1454                                 /* agent keys from the config file are preferred */
1455                                 if (key_equal(key, id->key)) {
1456                                         key_free(key);
1457                                         free(comment);
1458                                         TAILQ_REMOVE(&files, id, next);
1459                                         TAILQ_INSERT_TAIL(preferred, id, next);
1460                                         id->ac = ac;
1461                                         found = 1;
1462                                         break;
1463                                 }
1464                         }
1465                         if (!found && !options.identities_only) {
1466                                 id = xcalloc(1, sizeof(*id));
1467                                 id->key = key;
1468                                 id->filename = comment;
1469                                 id->ac = ac;
1470                                 TAILQ_INSERT_TAIL(&agent, id, next);
1471                         }
1472                 }
1473                 /* append remaining agent keys */
1474                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1475                         TAILQ_REMOVE(&agent, id, next);
1476                         TAILQ_INSERT_TAIL(preferred, id, next);
1477                 }
1478                 authctxt->agent = ac;
1479         }
1480         /* append remaining keys from the config file */
1481         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1482                 TAILQ_REMOVE(&files, id, next);
1483                 TAILQ_INSERT_TAIL(preferred, id, next);
1484         }
1485         TAILQ_FOREACH(id, preferred, next) {
1486                 debug2("key: %s (%p),%s", id->filename, id->key,
1487                     id->userprovided ? " explicit" : "");
1488         }
1489 }
1490
1491 static void
1492 pubkey_cleanup(Authctxt *authctxt)
1493 {
1494         Identity *id;
1495
1496         if (authctxt->agent != NULL)
1497                 ssh_close_authentication_connection(authctxt->agent);
1498         for (id = TAILQ_FIRST(&authctxt->keys); id;
1499             id = TAILQ_FIRST(&authctxt->keys)) {
1500                 TAILQ_REMOVE(&authctxt->keys, id, next);
1501                 if (id->key)
1502                         key_free(id->key);
1503                 free(id->filename);
1504                 free(id);
1505         }
1506 }
1507
1508 int
1509 userauth_pubkey(Authctxt *authctxt)
1510 {
1511         Identity *id;
1512         int sent = 0;
1513
1514         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1515                 if (id->tried++)
1516                         return (0);
1517                 /* move key to the end of the queue */
1518                 TAILQ_REMOVE(&authctxt->keys, id, next);
1519                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1520                 /*
1521                  * send a test message if we have the public key. for
1522                  * encrypted keys we cannot do this and have to load the
1523                  * private key instead
1524                  */
1525                 if (id->key && id->key->type != KEY_RSA1) {
1526                         debug("Offering %s public key: %s", key_type(id->key),
1527                             id->filename);
1528                         sent = send_pubkey_test(authctxt, id);
1529                 } else if (id->key == NULL) {
1530                         debug("Trying private key: %s", id->filename);
1531                         id->key = load_identity_file(id->filename,
1532                             id->userprovided);
1533                         if (id->key != NULL) {
1534                                 id->isprivate = 1;
1535                                 sent = sign_and_send_pubkey(authctxt, id);
1536                                 key_free(id->key);
1537                                 id->key = NULL;
1538                         }
1539                 }
1540                 if (sent)
1541                         return (sent);
1542         }
1543         return (0);
1544 }
1545
1546 /*
1547  * Send userauth request message specifying keyboard-interactive method.
1548  */
1549 int
1550 userauth_kbdint(Authctxt *authctxt)
1551 {
1552         static int attempt = 0;
1553
1554         if (attempt++ >= options.number_of_password_prompts)
1555                 return 0;
1556         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1557         if (attempt > 1 && !authctxt->info_req_seen) {
1558                 debug3("userauth_kbdint: disable: no info_req_seen");
1559                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1560                 return 0;
1561         }
1562
1563         debug2("userauth_kbdint");
1564         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1565         packet_put_cstring(authctxt->server_user);
1566         packet_put_cstring(authctxt->service);
1567         packet_put_cstring(authctxt->method->name);
1568         packet_put_cstring("");                                 /* lang */
1569         packet_put_cstring(options.kbd_interactive_devices ?
1570             options.kbd_interactive_devices : "");
1571         packet_send();
1572
1573         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1574         return 1;
1575 }
1576
1577 /*
1578  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1579  */
1580 void
1581 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1582 {
1583         Authctxt *authctxt = ctxt;
1584         char *name, *inst, *lang, *prompt, *response;
1585         u_int num_prompts, i;
1586         int echo = 0;
1587
1588         debug2("input_userauth_info_req");
1589
1590         if (authctxt == NULL)
1591                 fatal("input_userauth_info_req: no authentication context");
1592
1593         authctxt->info_req_seen = 1;
1594
1595         name = packet_get_string(NULL);
1596         inst = packet_get_string(NULL);
1597         lang = packet_get_string(NULL);
1598         if (strlen(name) > 0)
1599                 logit("%s", name);
1600         if (strlen(inst) > 0)
1601                 logit("%s", inst);
1602         free(name);
1603         free(inst);
1604         free(lang);
1605
1606         num_prompts = packet_get_int();
1607         /*
1608          * Begin to build info response packet based on prompts requested.
1609          * We commit to providing the correct number of responses, so if
1610          * further on we run into a problem that prevents this, we have to
1611          * be sure and clean this up and send a correct error response.
1612          */
1613         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1614         packet_put_int(num_prompts);
1615
1616         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1617         for (i = 0; i < num_prompts; i++) {
1618                 prompt = packet_get_string(NULL);
1619                 echo = packet_get_char();
1620
1621                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1622
1623                 packet_put_cstring(response);
1624                 memset(response, 0, strlen(response));
1625                 free(response);
1626                 free(prompt);
1627         }
1628         packet_check_eom(); /* done with parsing incoming message. */
1629
1630         packet_add_padding(64);
1631         packet_send();
1632 }
1633
1634 static int
1635 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1636     u_char *data, u_int datalen)
1637 {
1638         Buffer b;
1639         struct stat st;
1640         pid_t pid;
1641         int to[2], from[2], status, version = 2;
1642
1643         debug2("ssh_keysign called");
1644
1645         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1646                 error("ssh_keysign: not installed: %s", strerror(errno));
1647                 return -1;
1648         }
1649         if (fflush(stdout) != 0)
1650                 error("ssh_keysign: fflush: %s", strerror(errno));
1651         if (pipe(to) < 0) {
1652                 error("ssh_keysign: pipe: %s", strerror(errno));
1653                 return -1;
1654         }
1655         if (pipe(from) < 0) {
1656                 error("ssh_keysign: pipe: %s", strerror(errno));
1657                 return -1;
1658         }
1659         if ((pid = fork()) < 0) {
1660                 error("ssh_keysign: fork: %s", strerror(errno));
1661                 return -1;
1662         }
1663         if (pid == 0) {
1664                 /* keep the socket on exec */
1665                 fcntl(packet_get_connection_in(), F_SETFD, 0);
1666                 permanently_drop_suid(getuid());
1667                 close(from[0]);
1668                 if (dup2(from[1], STDOUT_FILENO) < 0)
1669                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1670                 close(to[1]);
1671                 if (dup2(to[0], STDIN_FILENO) < 0)
1672                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1673                 close(from[1]);
1674                 close(to[0]);
1675                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1676                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1677                     strerror(errno));
1678         }
1679         close(from[1]);
1680         close(to[0]);
1681
1682         buffer_init(&b);
1683         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1684         buffer_put_string(&b, data, datalen);
1685         if (ssh_msg_send(to[1], version, &b) == -1)
1686                 fatal("ssh_keysign: couldn't send request");
1687
1688         if (ssh_msg_recv(from[0], &b) < 0) {
1689                 error("ssh_keysign: no reply");
1690                 buffer_free(&b);
1691                 return -1;
1692         }
1693         close(from[0]);
1694         close(to[1]);
1695
1696         while (waitpid(pid, &status, 0) < 0)
1697                 if (errno != EINTR)
1698                         break;
1699
1700         if (buffer_get_char(&b) != version) {
1701                 error("ssh_keysign: bad version");
1702                 buffer_free(&b);
1703                 return -1;
1704         }
1705         *sigp = buffer_get_string(&b, lenp);
1706         buffer_free(&b);
1707
1708         return 0;
1709 }
1710
1711 int
1712 userauth_hostbased(Authctxt *authctxt)
1713 {
1714         Key *private = NULL;
1715         Sensitive *sensitive = authctxt->sensitive;
1716         Buffer b;
1717         u_char *signature, *blob;
1718         char *chost, *pkalg, *p;
1719         const char *service;
1720         u_int blen, slen;
1721         int ok, i, found = 0;
1722
1723         /* check for a useful key */
1724         for (i = 0; i < sensitive->nkeys; i++) {
1725                 private = sensitive->keys[i];
1726                 if (private && private->type != KEY_RSA1) {
1727                         found = 1;
1728                         /* we take and free the key */
1729                         sensitive->keys[i] = NULL;
1730                         break;
1731                 }
1732         }
1733         if (!found) {
1734                 debug("No more client hostkeys for hostbased authentication.");
1735                 return 0;
1736         }
1737         if (key_to_blob(private, &blob, &blen) == 0) {
1738                 key_free(private);
1739                 return 0;
1740         }
1741         /* figure out a name for the client host */
1742         p = get_local_name(packet_get_connection_in());
1743         if (p == NULL) {
1744                 error("userauth_hostbased: cannot get local ipaddr/name");
1745                 key_free(private);
1746                 free(blob);
1747                 return 0;
1748         }
1749         xasprintf(&chost, "%s.", p);
1750         debug2("userauth_hostbased: chost %s", chost);
1751         free(p);
1752
1753         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1754             authctxt->service;
1755         pkalg = xstrdup(key_ssh_name(private));
1756         buffer_init(&b);
1757         /* construct data */
1758         buffer_put_string(&b, session_id2, session_id2_len);
1759         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1760         buffer_put_cstring(&b, authctxt->server_user);
1761         buffer_put_cstring(&b, service);
1762         buffer_put_cstring(&b, authctxt->method->name);
1763         buffer_put_cstring(&b, pkalg);
1764         buffer_put_string(&b, blob, blen);
1765         buffer_put_cstring(&b, chost);
1766         buffer_put_cstring(&b, authctxt->local_user);
1767 #ifdef DEBUG_PK
1768         buffer_dump(&b);
1769 #endif
1770         if (sensitive->external_keysign)
1771                 ok = ssh_keysign(private, &signature, &slen,
1772                     buffer_ptr(&b), buffer_len(&b));
1773         else
1774                 ok = key_sign(private, &signature, &slen,
1775                     buffer_ptr(&b), buffer_len(&b));
1776         key_free(private);
1777         buffer_free(&b);
1778         if (ok != 0) {
1779                 error("key_sign failed");
1780                 free(chost);
1781                 free(pkalg);
1782                 free(blob);
1783                 return 0;
1784         }
1785         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1786         packet_put_cstring(authctxt->server_user);
1787         packet_put_cstring(authctxt->service);
1788         packet_put_cstring(authctxt->method->name);
1789         packet_put_cstring(pkalg);
1790         packet_put_string(blob, blen);
1791         packet_put_cstring(chost);
1792         packet_put_cstring(authctxt->local_user);
1793         packet_put_string(signature, slen);
1794         memset(signature, 's', slen);
1795         free(signature);
1796         free(chost);
1797         free(pkalg);
1798         free(blob);
1799
1800         packet_send();
1801         return 1;
1802 }
1803
1804 #ifdef JPAKE
1805 int
1806 userauth_jpake(Authctxt *authctxt)
1807 {
1808         struct jpake_ctx *pctx;
1809         u_char *x1_proof, *x2_proof;
1810         u_int x1_proof_len, x2_proof_len;
1811         static int attempt = 0; /* XXX share with userauth_password's? */
1812
1813         if (attempt++ >= options.number_of_password_prompts)
1814                 return 0;
1815         if (attempt != 1)
1816                 error("Permission denied, please try again.");
1817
1818         if (authctxt->methoddata != NULL)
1819                 fatal("%s: authctxt->methoddata already set (%p)",
1820                     __func__, authctxt->methoddata);
1821
1822         authctxt->methoddata = pctx = jpake_new();
1823
1824         /*
1825          * Send request immediately, to get the protocol going while
1826          * we do the initial computations.
1827          */
1828         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1829         packet_put_cstring(authctxt->server_user);
1830         packet_put_cstring(authctxt->service);
1831         packet_put_cstring(authctxt->method->name);
1832         packet_send();
1833         packet_write_wait();
1834
1835         jpake_step1(pctx->grp,
1836             &pctx->client_id, &pctx->client_id_len,
1837             &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2,
1838             &x1_proof, &x1_proof_len,
1839             &x2_proof, &x2_proof_len);
1840
1841         JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__));
1842
1843         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1);
1844         packet_put_string(pctx->client_id, pctx->client_id_len);
1845         packet_put_bignum2(pctx->g_x1);
1846         packet_put_bignum2(pctx->g_x2);
1847         packet_put_string(x1_proof, x1_proof_len);
1848         packet_put_string(x2_proof, x2_proof_len);
1849         packet_send();
1850
1851         bzero(x1_proof, x1_proof_len);
1852         bzero(x2_proof, x2_proof_len);
1853         free(x1_proof);
1854         free(x2_proof);
1855
1856         /* Expect step 1 packet from peer */
1857         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1,
1858             input_userauth_jpake_server_step1);
1859         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS,
1860             &input_userauth_success_unexpected);
1861
1862         return 1;
1863 }
1864
1865 void
1866 userauth_jpake_cleanup(Authctxt *authctxt)
1867 {
1868         debug3("%s: clean up", __func__);
1869         if (authctxt->methoddata != NULL) {
1870                 jpake_free(authctxt->methoddata);
1871                 authctxt->methoddata = NULL;
1872         }
1873         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
1874 }
1875 #endif /* JPAKE */
1876
1877 /* find auth method */
1878
1879 /*
1880  * given auth method name, if configurable options permit this method fill
1881  * in auth_ident field and return true, otherwise return false.
1882  */
1883 static int
1884 authmethod_is_enabled(Authmethod *method)
1885 {
1886         if (method == NULL)
1887                 return 0;
1888         /* return false if options indicate this method is disabled */
1889         if  (method->enabled == NULL || *method->enabled == 0)
1890                 return 0;
1891         /* return false if batch mode is enabled but method needs interactive mode */
1892         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1893                 return 0;
1894         return 1;
1895 }
1896
1897 static Authmethod *
1898 authmethod_lookup(const char *name)
1899 {
1900         Authmethod *method = NULL;
1901         if (name != NULL)
1902                 for (method = authmethods; method->name != NULL; method++)
1903                         if (strcmp(name, method->name) == 0)
1904                                 return method;
1905         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1906         return NULL;
1907 }
1908
1909 /* XXX internal state */
1910 static Authmethod *current = NULL;
1911 static char *supported = NULL;
1912 static char *preferred = NULL;
1913
1914 /*
1915  * Given the authentication method list sent by the server, return the
1916  * next method we should try.  If the server initially sends a nil list,
1917  * use a built-in default list.
1918  */
1919 static Authmethod *
1920 authmethod_get(char *authlist)
1921 {
1922         char *name = NULL;
1923         u_int next;
1924
1925         /* Use a suitable default if we're passed a nil list.  */
1926         if (authlist == NULL || strlen(authlist) == 0)
1927                 authlist = options.preferred_authentications;
1928
1929         if (supported == NULL || strcmp(authlist, supported) != 0) {
1930                 debug3("start over, passed a different list %s", authlist);
1931                 free(supported);
1932                 supported = xstrdup(authlist);
1933                 preferred = options.preferred_authentications;
1934                 debug3("preferred %s", preferred);
1935                 current = NULL;
1936         } else if (current != NULL && authmethod_is_enabled(current))
1937                 return current;
1938
1939         for (;;) {
1940                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1941                         debug("No more authentication methods to try.");
1942                         current = NULL;
1943                         return NULL;
1944                 }
1945                 preferred += next;
1946                 debug3("authmethod_lookup %s", name);
1947                 debug3("remaining preferred: %s", preferred);
1948                 if ((current = authmethod_lookup(name)) != NULL &&
1949                     authmethod_is_enabled(current)) {
1950                         debug3("authmethod_is_enabled %s", name);
1951                         debug("Next authentication method: %s", name);
1952                         free(name);
1953                         return current;
1954                 }
1955                 free(name);
1956         }
1957 }
1958
1959 static char *
1960 authmethods_get(void)
1961 {
1962         Authmethod *method = NULL;
1963         Buffer b;
1964         char *list;
1965
1966         buffer_init(&b);
1967         for (method = authmethods; method->name != NULL; method++) {
1968                 if (authmethod_is_enabled(method)) {
1969                         if (buffer_len(&b) > 0)
1970                                 buffer_append(&b, ",", 1);
1971                         buffer_append(&b, method->name, strlen(method->name));
1972                 }
1973         }
1974         buffer_append(&b, "\0", 1);
1975         list = xstrdup(buffer_ptr(&b));
1976         buffer_free(&b);
1977         return list;
1978 }
1979