openssh/sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.171 2009/03/05 07:18:19 djm Exp $ */
   2 /*
   3  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   4  * Copyright (c) 2008 Damien Miller.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include "includes.h"
  28
  29 #include <sys/types.h>
  30 #include <sys/socket.h>
  31 #include <sys/wait.h>
  32 #include <sys/stat.h>
  33
  34 #include <errno.h>
  35 #include <netdb.h>
  36 #include <pwd.h>
  37 #include <signal.h>
  38 #include <stdarg.h>
  39 #include <stdio.h>
  40 #include <string.h>
  41 #include <unistd.h>
  42 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H)
  43 #include <vis.h>
  44 #endif
  45
  46 #include "openbsd-compat/sys-queue.h"
  47
  48 #include "xmalloc.h"
  49 #include "ssh.h"
  50 #include "ssh2.h"
  51 #include "buffer.h"
  52 #include "packet.h"
  53 #include "compat.h"
  54 #include "cipher.h"
  55 #include "key.h"
  56 #include "kex.h"
  57 #include "myproposal.h"
  58 #include "sshconnect.h"
  59 #include "authfile.h"
  60 #include "dh.h"
  61 #include "authfd.h"
  62 #include "log.h"
  63 #include "readconf.h"
  64 #include "misc.h"
  65 #include "match.h"
  66 #include "dispatch.h"
  67 #include "canohost.h"
  68 #include "msg.h"
  69 #include "pathnames.h"
  70 #include "uidswap.h"
  71 #include "schnorr.h"
  72 #include "jpake.h"
  73
  74 #ifdef GSSAPI
  75 #include "ssh-gss.h"
  76 #endif
  77
  78 /* import */
  79 extern char *client_version_string;
  80 extern char *server_version_string;
  81 extern Options options;
  82 extern Kex *xxx_kex;
  83
  84 /* tty_flag is set in ssh.c. use this in ssh_userauth2 */
  85 /* if it is set then prevent the switch to the null cipher */
  86
  87 extern int tty_flag;
  88
  89 /* tty_flag is set in ssh.c. use this in ssh_userauth2 */
  90 /* if it is set then prevent the switch to the null cipher */
  91
  92 extern int tty_flag;
  93
  94 /* tty_flag is set in ssh.c. use this in ssh_userauth2 */
  95 /* if it is set then prevent the switch to the null cipher */
  96
  97 extern int tty_flag;
  98
  99 /*
 100  * SSH2 key exchange
 101  */
 102
 103 u_char *session_id2 = NULL;
 104 u_int session_id2_len = 0;
 105
 106 char *xxx_host;
 107 struct sockaddr *xxx_hostaddr;
 108
 109 Kex *xxx_kex = NULL;
 110
 111 static int
 112 verify_host_key_callback(Key *hostkey)
 113 {
 114         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
 115                 fatal("Host key verification failed.");
 116         return 0;
 117 }
 118
 119 void
 120 ssh_kex2(char *host, struct sockaddr *hostaddr)
 121 {
 122         Kex *kex;
 123
 124 #ifdef GSSAPI
 125         char *orig = NULL, *gss = NULL;
 126         char *gss_host = NULL;
 127 #endif
 128
 129         xxx_host = host;
 130         xxx_hostaddr = hostaddr;
 131
 132 #ifdef GSSAPI
 133         if (options.gss_keyex) {
 134                 /* Add the GSSAPI mechanisms currently supported on this
 135                  * client to the key exchange algorithm proposal */
 136                 orig = myproposal[PROPOSAL_KEX_ALGS];
 137
 138                 if (options.gss_trust_dns)
 139                         gss_host = (char *)get_canonical_hostname(1);
 140                 else
 141                         gss_host = host;
 142
 143                 gss = ssh_gssapi_client_mechanisms(gss_host, options.gss_client_identity);
 144                 if (gss) {
 145                         debug("Offering GSSAPI proposal: %s", gss);
 146                         xasprintf(&myproposal[PROPOSAL_KEX_ALGS],
 147                             "%s,%s", gss, orig);
 148                 }
 149         }
 150 #endif
 151
 152         if (options.ciphers == (char *)-1) {
 153                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 154                 options.ciphers = NULL;
 155         }
 156         if (options.ciphers != NULL) {
 157                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 158                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 159         }
 160         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 161             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 162         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 163             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 164         if (options.compression) {
 165                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 166                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 167         } else {
 168                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 169                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 170         }
 171         if (options.macs != NULL) {
 172                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 173                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 174         }
 175         if (options.hostkeyalgorithms != NULL)
 176                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 177                     options.hostkeyalgorithms;
 178
 179 #ifdef GSSAPI
 180         /* If we've got GSSAPI algorithms, then we also support the
 181          * 'null' hostkey, as a last resort */
 182         if (options.gss_keyex && gss) {
 183                 orig = myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
 184                 xasprintf(&myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS],
 185                     "%s,null", orig);
 186                 xfree(gss);
 187         }
 188 #endif
 189
 190         if (options.rekey_limit)
 191                 packet_set_rekey_limit((u_int32_t)options.rekey_limit);
 192
 193         /* start key exchange */
 194         kex = kex_setup(myproposal);
 195         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 196         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 197         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 198         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 199 #ifdef GSSAPI
 200         if (options.gss_keyex) {
 201                 kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client;
 202                 kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_client;
 203                 kex->kex[KEX_GSS_GEX_SHA1] = kexgss_client;
 204         }
 205 #endif
 206         kex->client_version_string=client_version_string;
 207         kex->server_version_string=server_version_string;
 208         kex->verify_host_key=&verify_host_key_callback;
 209
 210 #ifdef GSSAPI
 211         if (options.gss_keyex) {
 212                 kex->gss_deleg_creds = options.gss_deleg_creds;
 213                 kex->gss_trust_dns = options.gss_trust_dns;
 214                 kex->gss_client = options.gss_client_identity;
 215                 kex->gss_host = gss_host;
 216         }
 217 #endif
 218
 219         xxx_kex = kex;
 220
 221         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 222
 223         session_id2 = kex->session_id;
 224         session_id2_len = kex->session_id_len;
 225
 226 #ifdef DEBUG_KEXDH
 227         /* send 1st encrypted/maced/compressed message */
 228         packet_start(SSH2_MSG_IGNORE);
 229         packet_put_cstring("markus");
 230         packet_send();
 231         packet_write_wait();
 232 #endif
 233 }
 234
 235 /*
 236  * Authenticate user
 237  */
 238
 239 typedef struct Authctxt Authctxt;
 240 typedef struct Authmethod Authmethod;
 241 typedef struct identity Identity;
 242 typedef struct idlist Idlist;
 243
 244 struct identity {
 245         TAILQ_ENTRY(identity) next;
 246         AuthenticationConnection *ac;   /* set if agent supports key */
 247         Key     *key;                   /* public/private key */
 248         char    *filename;              /* comment for agent-only keys */
 249         int     tried;
 250         int     isprivate;              /* key points to the private key */
 251 };
 252 TAILQ_HEAD(idlist, identity);
 253
 254 struct Authctxt {
 255         const char *server_user;
 256         const char *local_user;
 257         const char *host;
 258         const char *service;
 259         Authmethod *method;
 260         int success;
 261         char *authlist;
 262         /* pubkey */
 263         Idlist keys;
 264         AuthenticationConnection *agent;
 265         /* hostbased */
 266         Sensitive *sensitive;
 267         /* kbd-interactive */
 268         int info_req_seen;
 269         /* generic */
 270         void *methoddata;
 271 };
 272 struct Authmethod {
 273         char    *name;          /* string to compare against server's list */
 274         int     (*userauth)(Authctxt *authctxt);
 275         void    (*cleanup)(Authctxt *authctxt);
 276         int     *enabled;       /* flag in option struct that enables method */
 277         int     *batch_flag;    /* flag in option struct that disables method */
 278 };
 279
 280 void    input_userauth_success(int, u_int32_t, void *);
 281 void    input_userauth_failure(int, u_int32_t, void *);
 282 void    input_userauth_banner(int, u_int32_t, void *);
 283 void    input_userauth_error(int, u_int32_t, void *);
 284 void    input_userauth_info_req(int, u_int32_t, void *);
 285 void    input_userauth_pk_ok(int, u_int32_t, void *);
 286 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 287 void    input_userauth_jpake_server_step1(int, u_int32_t, void *);
 288 void    input_userauth_jpake_server_step2(int, u_int32_t, void *);
 289 void    input_userauth_jpake_server_confirm(int, u_int32_t, void *);
 290
 291 int     userauth_none(Authctxt *);
 292 int     userauth_pubkey(Authctxt *);
 293 int     userauth_passwd(Authctxt *);
 294 int     userauth_kbdint(Authctxt *);
 295 int     userauth_hostbased(Authctxt *);
 296 int     userauth_jpake(Authctxt *);
 297
 298 void    userauth_jpake_cleanup(Authctxt *);
 299
 300 #ifdef GSSAPI
 301 int     userauth_gssapi(Authctxt *authctxt);
 302 void    input_gssapi_response(int type, u_int32_t, void *);
 303 void    input_gssapi_token(int type, u_int32_t, void *);
 304 void    input_gssapi_hash(int type, u_int32_t, void *);
 305 void    input_gssapi_error(int, u_int32_t, void *);
 306 void    input_gssapi_errtok(int, u_int32_t, void *);
 307 int     userauth_gsskeyex(Authctxt *authctxt);
 308 #endif
 309
 310 void    userauth(Authctxt *, char *);
 311
 312 static int sign_and_send_pubkey(Authctxt *, Identity *);
 313 static void pubkey_prepare(Authctxt *);
 314 static void pubkey_cleanup(Authctxt *);
 315 static Key *load_identity_file(char *);
 316
 317 static Authmethod *authmethod_get(char *authlist);
 318 static Authmethod *authmethod_lookup(const char *name);
 319 static char *authmethods_get(void);
 320
 321 Authmethod authmethods[] = {
 322 #ifdef GSSAPI
 323         {"gssapi-keyex",
 324                 userauth_gsskeyex,
 325                 NULL,
 326                 &options.gss_authentication,
 327                 NULL},
 328         {"gssapi-with-mic",
 329                 userauth_gssapi,
 330                 NULL,
 331                 &options.gss_authentication,
 332                 NULL},
 333 #endif
 334         {"hostbased",
 335                 userauth_hostbased,
 336                 NULL,
 337                 &options.hostbased_authentication,
 338                 NULL},
 339         {"publickey",
 340                 userauth_pubkey,
 341                 NULL,
 342                 &options.pubkey_authentication,
 343                 NULL},
 344 #ifdef JPAKE
 345         {"jpake-01@openssh.com",
 346                 userauth_jpake,
 347                 userauth_jpake_cleanup,
 348                 &options.zero_knowledge_password_authentication,
 349                 &options.batch_mode},
 350 #endif
 351         {"keyboard-interactive",
 352                 userauth_kbdint,
 353                 NULL,
 354                 &options.kbd_interactive_authentication,
 355                 &options.batch_mode},
 356         {"password",
 357                 userauth_passwd,
 358                 NULL,
 359                 &options.password_authentication,
 360                 &options.batch_mode},
 361         {"none",
 362                 userauth_none,
 363                 NULL,
 364                 NULL,
 365                 NULL},
 366         {NULL, NULL, NULL, NULL, NULL}
 367 };
 368
 369 void
 370 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 371     Sensitive *sensitive)
 372 {
 373         Authctxt authctxt;
 374         int type;
 375
 376         if (options.challenge_response_authentication)
 377                 options.kbd_interactive_authentication = 1;
 378
 379         packet_start(SSH2_MSG_SERVICE_REQUEST);
 380         packet_put_cstring("ssh-userauth");
 381         packet_send();
 382         debug("SSH2_MSG_SERVICE_REQUEST sent");
 383         packet_write_wait();
 384         type = packet_read();
 385         if (type != SSH2_MSG_SERVICE_ACCEPT)
 386                 fatal("Server denied authentication request: %d", type);
 387         if (packet_remaining() > 0) {
 388                 char *reply = packet_get_string(NULL);
 389                 debug2("service_accept: %s", reply);
 390                 xfree(reply);
 391         } else {
 392                 debug2("buggy server: service_accept w/o service");
 393         }
 394         packet_check_eom();
 395         debug("SSH2_MSG_SERVICE_ACCEPT received");
 396
 397         if (options.preferred_authentications == NULL)
 398                 options.preferred_authentications = authmethods_get();
 399
 400         /* setup authentication context */
 401         memset(&authctxt, 0, sizeof(authctxt));
 402         pubkey_prepare(&authctxt);
 403         authctxt.server_user = server_user;
 404         authctxt.local_user = local_user;
 405         authctxt.host = host;
 406         authctxt.service = "ssh-connection";            /* service name */
 407         authctxt.success = 0;
 408         authctxt.method = authmethod_lookup("none");
 409         authctxt.authlist = NULL;
 410         authctxt.methoddata = NULL;
 411         authctxt.sensitive = sensitive;
 412         authctxt.info_req_seen = 0;
 413         if (authctxt.method == NULL)
 414                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 415
 416         /* initial userauth request */
 417         userauth_none(&authctxt);
 418
 419         dispatch_init(&input_userauth_error);
 420         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 421         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 422         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 423         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 424
 425         pubkey_cleanup(&authctxt);
 426         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 427
 428         /* if the user wants to use the none cipher do it */
 429         /* post authentication and only if the right conditions are met */
 430         /* both of the NONE commands must be true and there must be no */
 431         /* tty allocated */
 432         if ((options.none_switch == 1) && (options.none_enabled == 1))
 433         {
 434                 if (!tty_flag) /* no null on tty sessions */
 435                 {
 436                         debug("Requesting none rekeying...");
 437                         myproposal[PROPOSAL_ENC_ALGS_STOC] = "none";
 438                         myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none";
 439                         kex_prop2buf(&xxx_kex->my,myproposal);
 440                         packet_request_rekeying();
 441                         fprintf(stderr, "WARNING: ENABLED NONE CIPHER\n");
 442                 }
 443                 else
 444                 {
 445                         /* requested NONE cipher when in a tty */
 446                         debug("Cannot switch to NONE cipher with tty allocated");
 447                         fprintf(stderr, "NONE cipher switch disabled when a TTY is allocated\n");
 448                 }
 449         }
 450         debug("Authentication succeeded (%s).", authctxt.method->name);
 451 }
 452
 453 void
 454 userauth(Authctxt *authctxt, char *authlist)
 455 {
 456         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 457                 authctxt->method->cleanup(authctxt);
 458
 459         if (authctxt->methoddata) {
 460                 xfree(authctxt->methoddata);
 461                 authctxt->methoddata = NULL;
 462         }
 463         if (authlist == NULL) {
 464                 authlist = authctxt->authlist;
 465         } else {
 466                 if (authctxt->authlist)
 467                         xfree(authctxt->authlist);
 468                 authctxt->authlist = authlist;
 469         }
 470         for (;;) {
 471                 Authmethod *method = authmethod_get(authlist);
 472                 if (method == NULL)
 473                         fatal("Permission denied (%s).", authlist);
 474                 authctxt->method = method;
 475
 476                 /* reset the per method handler */
 477                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 478                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 479
 480                 /* and try new method */
 481                 if (method->userauth(authctxt) != 0) {
 482                         debug2("we sent a %s packet, wait for reply", method->name);
 483                         break;
 484                 } else {
 485                         debug2("we did not send a packet, disable method");
 486                         method->enabled = NULL;
 487                 }
 488         }
 489 }
 490
 491 /* ARGSUSED */
 492 void
 493 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 494 {
 495         fatal("input_userauth_error: bad message during authentication: "
 496             "type %d", type);
 497 }
 498
 499 /* ARGSUSED */
 500 void
 501 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 502 {
 503         char *msg, *raw, *lang;
 504         u_int len;
 505
 506         debug3("input_userauth_banner");
 507         raw = packet_get_string(&len);
 508         lang = packet_get_string(NULL);
 509         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
 510                 if (len > 65536)
 511                         len = 65536;
 512                 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
 513                 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL);
 514                 fprintf(stderr, "%s", msg);
 515                 xfree(msg);
 516         }
 517         xfree(raw);
 518         xfree(lang);
 519 }
 520
 521 /* ARGSUSED */
 522 void
 523 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 524 {
 525         Authctxt *authctxt = ctxt;
 526         if (authctxt == NULL)
 527                 fatal("input_userauth_success: no authentication context");
 528         if (authctxt->authlist) {
 529                 xfree(authctxt->authlist);
 530                 authctxt->authlist = NULL;
 531         }
 532         if (authctxt->methoddata) {
 533                 xfree(authctxt->methoddata);
 534                 authctxt->methoddata = NULL;
 535         }
 536         authctxt->success = 1;                  /* break out */
 537 }
 538
 539 /* ARGSUSED */
 540 void
 541 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 542 {
 543         Authctxt *authctxt = ctxt;
 544         char *authlist = NULL;
 545         int partial;
 546
 547         if (authctxt == NULL)
 548                 fatal("input_userauth_failure: no authentication context");
 549
 550         authlist = packet_get_string(NULL);
 551         partial = packet_get_char();
 552         packet_check_eom();
 553
 554         if (partial != 0)
 555                 logit("Authenticated with partial success.");
 556         debug("Authentications that can continue: %s", authlist);
 557
 558         userauth(authctxt, authlist);
 559 }
 560
 561 /* ARGSUSED */
 562 void
 563 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 564 {
 565         Authctxt *authctxt = ctxt;
 566         Key *key = NULL;
 567         Identity *id = NULL;
 568         Buffer b;
 569         int pktype, sent = 0;
 570         u_int alen, blen;
 571         char *pkalg, *fp;
 572         u_char *pkblob;
 573
 574         if (authctxt == NULL)
 575                 fatal("input_userauth_pk_ok: no authentication context");
 576         if (datafellows & SSH_BUG_PKOK) {
 577                 /* this is similar to SSH_BUG_PKAUTH */
 578                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 579                 pkblob = packet_get_string(&blen);
 580                 buffer_init(&b);
 581                 buffer_append(&b, pkblob, blen);
 582                 pkalg = buffer_get_string(&b, &alen);
 583                 buffer_free(&b);
 584         } else {
 585                 pkalg = packet_get_string(&alen);
 586                 pkblob = packet_get_string(&blen);
 587         }
 588         packet_check_eom();
 589
 590         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 591
 592         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 593                 debug("unknown pkalg %s", pkalg);
 594                 goto done;
 595         }
 596         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 597                 debug("no key from blob. pkalg %s", pkalg);
 598                 goto done;
 599         }
 600         if (key->type != pktype) {
 601                 error("input_userauth_pk_ok: type mismatch "
 602                     "for decoded key (received %d, expected %d)",
 603                     key->type, pktype);
 604                 goto done;
 605         }
 606         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 607         debug2("input_userauth_pk_ok: fp %s", fp);
 608         xfree(fp);
 609
 610         /*
 611          * search keys in the reverse order, because last candidate has been
 612          * moved to the end of the queue.  this also avoids confusion by
 613          * duplicate keys
 614          */
 615         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 616                 if (key_equal(key, id->key)) {
 617                         sent = sign_and_send_pubkey(authctxt, id);
 618                         break;
 619                 }
 620         }
 621 done:
 622         if (key != NULL)
 623                 key_free(key);
 624         xfree(pkalg);
 625         xfree(pkblob);
 626
 627         /* try another method if we did not send a packet */
 628         if (sent == 0)
 629                 userauth(authctxt, NULL);
 630 }
 631
 632 #ifdef GSSAPI
 633 int
 634 userauth_gssapi(Authctxt *authctxt)
 635 {
 636         Gssctxt *gssctxt = NULL;
 637         static gss_OID_set gss_supported = NULL;
 638         static u_int mech = 0;
 639         OM_uint32 min;
 640         int ok = 0;
 641         char *gss_host = NULL;
 642
 643         if (!options.gss_authentication) {
 644                 verbose("GSSAPI authentication disabled.");
 645                 return 0;
 646         }
 647
 648         if (options.gss_trust_dns)
 649                 gss_host = (char *)get_canonical_hostname(1);
 650         else
 651                 gss_host = (char *)authctxt->host;
 652
 653         /* Try one GSSAPI method at a time, rather than sending them all at
 654          * once. */
 655
 656         if (gss_supported == NULL)
 657                 if (GSS_ERROR(gss_indicate_mechs(&min, &gss_supported))) {
 658                         gss_supported = NULL;
 659                         return 0;
 660                 }
 661
 662         /* Check to see if the mechanism is usable before we offer it */
 663         while (mech < gss_supported->count && !ok) {
 664                 /* My DER encoding requires length<128 */
 665                 if (gss_supported->elements[mech].length < 128 &&
 666                     ssh_gssapi_check_mechanism(&gssctxt,
 667                     &gss_supported->elements[mech], gss_host,
 668                     options.gss_client_identity)) {
 669                         ok = 1; /* Mechanism works */
 670                 } else {
 671                         mech++;
 672                 }
 673         }
 674
 675         if (!ok)
 676                 return 0;
 677
 678         authctxt->methoddata=(void *)gssctxt;
 679
 680         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 681         packet_put_cstring(authctxt->server_user);
 682         packet_put_cstring(authctxt->service);
 683         packet_put_cstring(authctxt->method->name);
 684
 685         packet_put_int(1);
 686
 687         packet_put_int((gss_supported->elements[mech].length) + 2);
 688         packet_put_char(SSH_GSS_OIDTYPE);
 689         packet_put_char(gss_supported->elements[mech].length);
 690         packet_put_raw(gss_supported->elements[mech].elements,
 691             gss_supported->elements[mech].length);
 692
 693         packet_send();
 694
 695         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 696         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 697         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 698         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 699
 700         mech++; /* Move along to next candidate */
 701
 702         return 1;
 703 }
 704
 705 static OM_uint32
 706 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 707 {
 708         Authctxt *authctxt = ctxt;
 709         Gssctxt *gssctxt = authctxt->methoddata;
 710         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 711         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 712         gss_buffer_desc gssbuf;
 713         OM_uint32 status, ms, flags;
 714         Buffer b;
 715
 716         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 717             recv_tok, &send_tok, &flags);
 718
 719         if (send_tok.length > 0) {
 720                 if (GSS_ERROR(status))
 721                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 722                 else
 723                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 724
 725                 packet_put_string(send_tok.value, send_tok.length);
 726                 packet_send();
 727                 gss_release_buffer(&ms, &send_tok);
 728         }
 729
 730         if (status == GSS_S_COMPLETE) {
 731                 /* send either complete or MIC, depending on mechanism */
 732                 if (strcmp(authctxt->method->name,"gssapi")==0 ||
 733                     (!(flags & GSS_C_INTEG_FLAG))) {
 734                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 735                         packet_send();
 736                 } else {
 737                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 738                             authctxt->service, "gssapi-with-mic");
 739
 740                         gssbuf.value = buffer_ptr(&b);
 741                         gssbuf.length = buffer_len(&b);
 742
 743                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 744
 745                         if (!GSS_ERROR(status)) {
 746                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 747                                 packet_put_string(mic.value, mic.length);
 748
 749                                 packet_send();
 750                         }
 751
 752                         buffer_free(&b);
 753                         gss_release_buffer(&ms, &mic);
 754                 }
 755         }
 756
 757         return status;
 758 }
 759
 760 /* ARGSUSED */
 761 void
 762 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 763 {
 764         Authctxt *authctxt = ctxt;
 765         Gssctxt *gssctxt;
 766         u_int oidlen;
 767         u_char *oidv;
 768
 769         if (authctxt == NULL)
 770                 fatal("input_gssapi_response: no authentication context");
 771         gssctxt = authctxt->methoddata;
 772
 773         /* Setup our OID */
 774         oidv = packet_get_string(&oidlen);
 775
 776         if (oidlen <= 2 ||
 777             oidv[0] != SSH_GSS_OIDTYPE ||
 778             oidv[1] != oidlen - 2) {
 779                 xfree(oidv);
 780                 debug("Badly encoded mechanism OID received");
 781                 userauth(authctxt, NULL);
 782                 return;
 783         }
 784
 785         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 786                 fatal("Server returned different OID than expected");
 787
 788         packet_check_eom();
 789
 790         xfree(oidv);
 791
 792         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 793                 /* Start again with next method on list */
 794                 debug("Trying to start again");
 795                 userauth(authctxt, NULL);
 796                 return;
 797         }
 798 }
 799
 800 /* ARGSUSED */
 801 void
 802 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 803 {
 804         Authctxt *authctxt = ctxt;
 805         gss_buffer_desc recv_tok;
 806         OM_uint32 status;
 807         u_int slen;
 808
 809         if (authctxt == NULL)
 810                 fatal("input_gssapi_response: no authentication context");
 811
 812         recv_tok.value = packet_get_string(&slen);
 813         recv_tok.length = slen; /* safe typecast */
 814
 815         packet_check_eom();
 816
 817         status = process_gssapi_token(ctxt, &recv_tok);
 818
 819         xfree(recv_tok.value);
 820
 821         if (GSS_ERROR(status)) {
 822                 /* Start again with the next method in the list */
 823                 userauth(authctxt, NULL);
 824                 return;
 825         }
 826 }
 827
 828 /* ARGSUSED */
 829 void
 830 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 831 {
 832         Authctxt *authctxt = ctxt;
 833         Gssctxt *gssctxt;
 834         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 835         gss_buffer_desc recv_tok;
 836         OM_uint32 status, ms;
 837         u_int len;
 838
 839         if (authctxt == NULL)
 840                 fatal("input_gssapi_response: no authentication context");
 841         gssctxt = authctxt->methoddata;
 842
 843         recv_tok.value = packet_get_string(&len);
 844         recv_tok.length = len;
 845
 846         packet_check_eom();
 847
 848         /* Stick it into GSSAPI and see what it says */
 849         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 850             &recv_tok, &send_tok, NULL);
 851
 852         xfree(recv_tok.value);
 853         gss_release_buffer(&ms, &send_tok);
 854
 855         /* Server will be returning a failed packet after this one */
 856 }
 857
 858 /* ARGSUSED */
 859 void
 860 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 861 {
 862         OM_uint32 maj, min;
 863         char *msg;
 864         char *lang;
 865
 866         maj=packet_get_int();
 867         min=packet_get_int();
 868         msg=packet_get_string(NULL);
 869         lang=packet_get_string(NULL);
 870
 871         packet_check_eom();
 872
 873         debug("Server GSSAPI Error:\n%s", msg);
 874         xfree(msg);
 875         xfree(lang);
 876 }
 877
 878 #ifdef GSI
 879 extern
 880 const gss_OID_desc * const              gss_mech_globus_gssapi_openssl;
 881 #define is_gsi_oid(oid) \
 882   (oid->length == gss_mech_globus_gssapi_openssl->length && \
 883    (memcmp(oid->elements, gss_mech_globus_gssapi_openssl->elements, \
 884            oid->length) == 0))
 885 #endif
 886
 887 int
 888 userauth_gsskeyex(Authctxt *authctxt)
 889 {
 890         Buffer b;
 891         gss_buffer_desc gssbuf;
 892         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 893         OM_uint32 ms;
 894
 895         static int attempt = 0;
 896         if (attempt++ >= 1)
 897                 return (0);
 898
 899         if (gss_kex_context == NULL) {
 900                 debug("No valid Key exchange context");
 901                 return (0);
 902         }
 903
 904 #ifdef GSI
 905     if (options.implicit && is_gsi_oid(gss_kex_context->oid)) {
 906         ssh_gssapi_buildmic(&b, "", authctxt->service, "gssapi-keyex");
 907         } else {
 908 #endif
 909         ssh_gssapi_buildmic(&b, authctxt->server_user, authctxt->service,
 910                             "gssapi-keyex");
 911 #ifdef GSI
 912         }
 913 #endif
 914
 915         gssbuf.value = buffer_ptr(&b);
 916         gssbuf.length = buffer_len(&b);
 917
 918         if (GSS_ERROR(ssh_gssapi_sign(gss_kex_context, &gssbuf, &mic))) {
 919                 buffer_free(&b);
 920                 return (0);
 921         }
 922
 923         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 924 #ifdef GSI
 925     if (options.implicit && is_gsi_oid(gss_kex_context->oid)) {
 926         packet_put_cstring("");
 927         } else {
 928 #endif
 929         packet_put_cstring(authctxt->server_user);
 930 #ifdef GSI
 931         }
 932 #endif
 933         packet_put_cstring(authctxt->service);
 934         packet_put_cstring(authctxt->method->name);
 935         packet_put_string(mic.value, mic.length);
 936         packet_send();
 937
 938         buffer_free(&b);
 939         gss_release_buffer(&ms, &mic);
 940
 941         return (1);
 942 }
 943
 944 #endif /* GSSAPI */
 945
 946 int
 947 userauth_none(Authctxt *authctxt)
 948 {
 949         /* initial userauth request */
 950         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 951         packet_put_cstring(authctxt->server_user);
 952         packet_put_cstring(authctxt->service);
 953         packet_put_cstring(authctxt->method->name);
 954         packet_send();
 955         return 1;
 956 }
 957
 958 int
 959 userauth_passwd(Authctxt *authctxt)
 960 {
 961         static int attempt = 0;
 962         char prompt[150];
 963         char *password;
 964
 965         if (attempt++ >= options.number_of_password_prompts)
 966                 return 0;
 967
 968         if (attempt != 1)
 969                 error("Permission denied, please try again.");
 970
 971         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 972             authctxt->server_user, authctxt->host);
 973         password = read_passphrase(prompt, 0);
 974         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 975         packet_put_cstring(authctxt->server_user);
 976         packet_put_cstring(authctxt->service);
 977         packet_put_cstring(authctxt->method->name);
 978         packet_put_char(0);
 979         packet_put_cstring(password);
 980         memset(password, 0, strlen(password));
 981         xfree(password);
 982         packet_add_padding(64);
 983         packet_send();
 984
 985         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 986             &input_userauth_passwd_changereq);
 987
 988         return 1;
 989 }
 990
 991 /*
 992  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 993  */
 994 /* ARGSUSED */
 995 void
 996 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 997 {
 998         Authctxt *authctxt = ctxt;
 999         char *info, *lang, *password = NULL, *retype = NULL;
1000         char prompt[150];
1001
1002         debug2("input_userauth_passwd_changereq");
1003
1004         if (authctxt == NULL)
1005                 fatal("input_userauth_passwd_changereq: "
1006                     "no authentication context");
1007
1008         info = packet_get_string(NULL);
1009         lang = packet_get_string(NULL);
1010         if (strlen(info) > 0)
1011                 logit("%s", info);
1012         xfree(info);
1013         xfree(lang);
1014         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1015         packet_put_cstring(authctxt->server_user);
1016         packet_put_cstring(authctxt->service);
1017         packet_put_cstring(authctxt->method->name);
1018         packet_put_char(1);                     /* additional info */
1019         snprintf(prompt, sizeof(prompt),
1020             "Enter %.30s@%.128s's old password: ",
1021             authctxt->server_user, authctxt->host);
1022         password = read_passphrase(prompt, 0);
1023         packet_put_cstring(password);
1024         memset(password, 0, strlen(password));
1025         xfree(password);
1026         password = NULL;
1027         while (password == NULL) {
1028                 snprintf(prompt, sizeof(prompt),
1029                     "Enter %.30s@%.128s's new password: ",
1030                     authctxt->server_user, authctxt->host);
1031                 password = read_passphrase(prompt, RP_ALLOW_EOF);
1032                 if (password == NULL) {
1033                         /* bail out */
1034                         return;
1035                 }
1036                 snprintf(prompt, sizeof(prompt),
1037                     "Retype %.30s@%.128s's new password: ",
1038                     authctxt->server_user, authctxt->host);
1039                 retype = read_passphrase(prompt, 0);
1040                 if (strcmp(password, retype) != 0) {
1041                         memset(password, 0, strlen(password));
1042                         xfree(password);
1043                         logit("Mismatch; try again, EOF to quit.");
1044                         password = NULL;
1045                 }
1046                 memset(retype, 0, strlen(retype));
1047                 xfree(retype);
1048         }
1049         packet_put_cstring(password);
1050         memset(password, 0, strlen(password));
1051         xfree(password);
1052         packet_add_padding(64);
1053         packet_send();
1054
1055         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
1056             &input_userauth_passwd_changereq);
1057 }
1058
1059 #ifdef JPAKE
1060 static char *
1061 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt)
1062 {
1063         /* OpenBSD crypt(3) handles all of these */
1064         if (strcmp(crypt_scheme, "crypt") == 0 ||
1065             strcmp(crypt_scheme, "bcrypt") == 0 ||
1066             strcmp(crypt_scheme, "md5crypt") == 0 ||
1067             strcmp(crypt_scheme, "crypt-extended") == 0)
1068                 return xstrdup(crypt(password, salt));
1069         error("%s: unsupported password encryption scheme \"%.100s\"",
1070             __func__, crypt_scheme);
1071         return NULL;
1072 }
1073
1074 static BIGNUM *
1075 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme,
1076     const char *salt)
1077 {
1078         char prompt[256], *password, *crypted;
1079         u_char *secret;
1080         u_int secret_len;
1081         BIGNUM *ret;
1082
1083         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ",
1084             authctxt->server_user, authctxt->host);
1085         password = read_passphrase(prompt, 0);
1086
1087         if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) {
1088                 logit("Disabling %s authentication", authctxt->method->name);
1089                 authctxt->method->enabled = NULL;
1090                 /* Continue with an empty password to fail gracefully */
1091                 crypted = xstrdup("");
1092         }
1093
1094 #ifdef JPAKE_DEBUG
1095         debug3("%s: salt = %s", __func__, salt);
1096         debug3("%s: scheme = %s", __func__, crypt_scheme);
1097         debug3("%s: crypted = %s", __func__, crypted);
1098 #endif
1099
1100         if (hash_buffer(crypted, strlen(crypted), EVP_sha256(),
1101             &secret, &secret_len) != 0)
1102                 fatal("%s: hash_buffer", __func__);
1103
1104         bzero(password, strlen(password));
1105         bzero(crypted, strlen(crypted));
1106         xfree(password);
1107         xfree(crypted);
1108
1109         if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL)
1110                 fatal("%s: BN_bin2bn (secret)", __func__);
1111         bzero(secret, secret_len);
1112         xfree(secret);
1113
1114         return ret;
1115 }
1116
1117 /* ARGSUSED */
1118 void
1119 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt)
1120 {
1121         Authctxt *authctxt = ctxt;
1122         struct jpake_ctx *pctx = authctxt->methoddata;
1123         u_char *x3_proof, *x4_proof, *x2_s_proof;
1124         u_int x3_proof_len, x4_proof_len, x2_s_proof_len;
1125         char *crypt_scheme, *salt;
1126
1127         /* Disable this message */
1128         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL);
1129
1130         if ((pctx->g_x3 = BN_new()) == NULL ||
1131             (pctx->g_x4 = BN_new()) == NULL)
1132                 fatal("%s: BN_new", __func__);
1133
1134         /* Fetch step 1 values */
1135         crypt_scheme = packet_get_string(NULL);
1136         salt = packet_get_string(NULL);
1137         pctx->server_id = packet_get_string(&pctx->server_id_len);
1138         packet_get_bignum2(pctx->g_x3);
1139         packet_get_bignum2(pctx->g_x4);
1140         x3_proof = packet_get_string(&x3_proof_len);
1141         x4_proof = packet_get_string(&x4_proof_len);
1142         packet_check_eom();
1143
1144         JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__));
1145
1146         /* Obtain password and derive secret */
1147         pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt);
1148         bzero(crypt_scheme, strlen(crypt_scheme));
1149         bzero(salt, strlen(salt));
1150         xfree(crypt_scheme);
1151         xfree(salt);
1152         JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__));
1153
1154         /* Calculate step 2 values */
1155         jpake_step2(pctx->grp, pctx->s, pctx->g_x1,
1156             pctx->g_x3, pctx->g_x4, pctx->x2,
1157             pctx->server_id, pctx->server_id_len,
1158             pctx->client_id, pctx->client_id_len,
1159             x3_proof, x3_proof_len,
1160             x4_proof, x4_proof_len,
1161             &pctx->a,
1162             &x2_s_proof, &x2_s_proof_len);
1163
1164         bzero(x3_proof, x3_proof_len);
1165         bzero(x4_proof, x4_proof_len);
1166         xfree(x3_proof);
1167         xfree(x4_proof);
1168
1169         JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__));
1170
1171         /* Send values for step 2 */
1172         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2);
1173         packet_put_bignum2(pctx->a);
1174         packet_put_string(x2_s_proof, x2_s_proof_len);
1175         packet_send();
1176
1177         bzero(x2_s_proof, x2_s_proof_len);
1178         xfree(x2_s_proof);
1179
1180         /* Expect step 2 packet from peer */
1181         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2,
1182             input_userauth_jpake_server_step2);
1183 }
1184
1185 /* ARGSUSED */
1186 void
1187 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt)
1188 {
1189         Authctxt *authctxt = ctxt;
1190         struct jpake_ctx *pctx = authctxt->methoddata;
1191         u_char *x4_s_proof;
1192         u_int x4_s_proof_len;
1193
1194         /* Disable this message */
1195         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL);
1196
1197         if ((pctx->b = BN_new()) == NULL)
1198                 fatal("%s: BN_new", __func__);
1199
1200         /* Fetch step 2 values */
1201         packet_get_bignum2(pctx->b);
1202         x4_s_proof = packet_get_string(&x4_s_proof_len);
1203         packet_check_eom();
1204
1205         JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__));
1206
1207         /* Derive shared key and calculate confirmation hash */
1208         jpake_key_confirm(pctx->grp, pctx->s, pctx->b,
1209             pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4,
1210             pctx->client_id, pctx->client_id_len,
1211             pctx->server_id, pctx->server_id_len,
1212             session_id2, session_id2_len,
1213             x4_s_proof, x4_s_proof_len,
1214             &pctx->k,
1215             &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len);
1216
1217         bzero(x4_s_proof, x4_s_proof_len);
1218         xfree(x4_s_proof);
1219
1220         JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__));
1221
1222         /* Send key confirmation proof */
1223         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM);
1224         packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len);
1225         packet_send();
1226
1227         /* Expect confirmation from peer */
1228         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM,
1229             input_userauth_jpake_server_confirm);
1230 }
1231
1232 /* ARGSUSED */
1233 void
1234 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt)
1235 {
1236         Authctxt *authctxt = ctxt;
1237         struct jpake_ctx *pctx = authctxt->methoddata;
1238
1239         /* Disable this message */
1240         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL);
1241
1242         pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len);
1243         packet_check_eom();
1244
1245         JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__));
1246
1247         /* Verify expected confirmation hash */
1248         if (jpake_check_confirm(pctx->k,
1249             pctx->server_id, pctx->server_id_len,
1250             session_id2, session_id2_len,
1251             pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1)
1252                 debug("%s: %s success", __func__, authctxt->method->name);
1253         else {
1254                 debug("%s: confirmation mismatch", __func__);
1255                 /* XXX stash this so if auth succeeds then we can warn/kill */
1256         }
1257
1258         userauth_jpake_cleanup(authctxt);
1259 }
1260 #endif /* JPAKE */
1261
1262 static int
1263 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
1264     u_char *data, u_int datalen)
1265 {
1266         Key *prv;
1267         int ret;
1268
1269         /* the agent supports this key */
1270         if (id->ac)
1271                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1272                     data, datalen));
1273         /*
1274          * we have already loaded the private key or
1275          * the private key is stored in external hardware
1276          */
1277         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1278                 return (key_sign(id->key, sigp, lenp, data, datalen));
1279         /* load the private key from the file */
1280         if ((prv = load_identity_file(id->filename)) == NULL)
1281                 return (-1);
1282         ret = key_sign(prv, sigp, lenp, data, datalen);
1283         key_free(prv);
1284         return (ret);
1285 }
1286
1287 static int
1288 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1289 {
1290         Buffer b;
1291         u_char *blob, *signature;
1292         u_int bloblen, slen;
1293         u_int skip = 0;
1294         int ret = -1;
1295         int have_sig = 1;
1296
1297         debug3("sign_and_send_pubkey");
1298
1299         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1300                 /* we cannot handle this key */
1301                 debug3("sign_and_send_pubkey: cannot handle key");
1302                 return 0;
1303         }
1304         /* data to be signed */
1305         buffer_init(&b);
1306         if (datafellows & SSH_OLD_SESSIONID) {
1307                 buffer_append(&b, session_id2, session_id2_len);
1308                 skip = session_id2_len;
1309         } else {
1310                 buffer_put_string(&b, session_id2, session_id2_len);
1311                 skip = buffer_len(&b);
1312         }
1313         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1314         buffer_put_cstring(&b, authctxt->server_user);
1315         buffer_put_cstring(&b,
1316             datafellows & SSH_BUG_PKSERVICE ?
1317             "ssh-userauth" :
1318             authctxt->service);
1319         if (datafellows & SSH_BUG_PKAUTH) {
1320                 buffer_put_char(&b, have_sig);
1321         } else {
1322                 buffer_put_cstring(&b, authctxt->method->name);
1323                 buffer_put_char(&b, have_sig);
1324                 buffer_put_cstring(&b, key_ssh_name(id->key));
1325         }
1326         buffer_put_string(&b, blob, bloblen);
1327
1328         /* generate signature */
1329         ret = identity_sign(id, &signature, &slen,
1330             buffer_ptr(&b), buffer_len(&b));
1331         if (ret == -1) {
1332                 xfree(blob);
1333                 buffer_free(&b);
1334                 return 0;
1335         }
1336 #ifdef DEBUG_PK
1337         buffer_dump(&b);
1338 #endif
1339         if (datafellows & SSH_BUG_PKSERVICE) {
1340                 buffer_clear(&b);
1341                 buffer_append(&b, session_id2, session_id2_len);
1342                 skip = session_id2_len;
1343                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1344                 buffer_put_cstring(&b, authctxt->server_user);
1345                 buffer_put_cstring(&b, authctxt->service);
1346                 buffer_put_cstring(&b, authctxt->method->name);
1347                 buffer_put_char(&b, have_sig);
1348                 if (!(datafellows & SSH_BUG_PKAUTH))
1349                         buffer_put_cstring(&b, key_ssh_name(id->key));
1350                 buffer_put_string(&b, blob, bloblen);
1351         }
1352         xfree(blob);
1353
1354         /* append signature */
1355         buffer_put_string(&b, signature, slen);
1356         xfree(signature);
1357
1358         /* skip session id and packet type */
1359         if (buffer_len(&b) < skip + 1)
1360                 fatal("userauth_pubkey: internal error");
1361         buffer_consume(&b, skip + 1);
1362
1363         /* put remaining data from buffer into packet */
1364         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1365         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1366         buffer_free(&b);
1367         packet_send();
1368
1369         return 1;
1370 }
1371
1372 static int
1373 send_pubkey_test(Authctxt *authctxt, Identity *id)
1374 {
1375         u_char *blob;
1376         u_int bloblen, have_sig = 0;
1377
1378         debug3("send_pubkey_test");
1379
1380         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1381                 /* we cannot handle this key */
1382                 debug3("send_pubkey_test: cannot handle key");
1383                 return 0;
1384         }
1385         /* register callback for USERAUTH_PK_OK message */
1386         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1387
1388         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1389         packet_put_cstring(authctxt->server_user);
1390         packet_put_cstring(authctxt->service);
1391         packet_put_cstring(authctxt->method->name);
1392         packet_put_char(have_sig);
1393         if (!(datafellows & SSH_BUG_PKAUTH))
1394                 packet_put_cstring(key_ssh_name(id->key));
1395         packet_put_string(blob, bloblen);
1396         xfree(blob);
1397         packet_send();
1398         return 1;
1399 }
1400
1401 static Key *
1402 load_identity_file(char *filename)
1403 {
1404         Key *private;
1405         char prompt[300], *passphrase;
1406         int perm_ok, quit, i;
1407         struct stat st;
1408
1409         if (stat(filename, &st) < 0) {
1410                 debug3("no such identity: %s", filename);
1411                 return NULL;
1412         }
1413         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1414         if (!perm_ok)
1415                 return NULL;
1416         if (private == NULL) {
1417                 if (options.batch_mode)
1418                         return NULL;
1419                 snprintf(prompt, sizeof prompt,
1420                     "Enter passphrase for key '%.100s': ", filename);
1421                 for (i = 0; i < options.number_of_password_prompts; i++) {
1422                         passphrase = read_passphrase(prompt, 0);
1423                         if (strcmp(passphrase, "") != 0) {
1424                                 private = key_load_private_type(KEY_UNSPEC,
1425                                     filename, passphrase, NULL, NULL);
1426                                 quit = 0;
1427                         } else {
1428                                 debug2("no passphrase given, try next key");
1429                                 quit = 1;
1430                         }
1431                         memset(passphrase, 0, strlen(passphrase));
1432                         xfree(passphrase);
1433                         if (private != NULL || quit)
1434                                 break;
1435                         debug2("bad passphrase given, try again...");
1436                 }
1437         }
1438         return private;
1439 }
1440
1441 /*
1442  * try keys in the following order:
1443  *      1. agent keys that are found in the config file
1444  *      2. other agent keys
1445  *      3. keys that are only listed in the config file
1446  */
1447 static void
1448 pubkey_prepare(Authctxt *authctxt)
1449 {
1450         Identity *id;
1451         Idlist agent, files, *preferred;
1452         Key *key;
1453         AuthenticationConnection *ac;
1454         char *comment;
1455         int i, found;
1456
1457         TAILQ_INIT(&agent);     /* keys from the agent */
1458         TAILQ_INIT(&files);     /* keys from the config file */
1459         preferred = &authctxt->keys;
1460         TAILQ_INIT(preferred);  /* preferred order of keys */
1461
1462         /* list of keys stored in the filesystem */
1463         for (i = 0; i < options.num_identity_files; i++) {
1464                 key = options.identity_keys[i];
1465                 if (key && key->type == KEY_RSA1)
1466                         continue;
1467                 options.identity_keys[i] = NULL;
1468                 id = xcalloc(1, sizeof(*id));
1469                 id->key = key;
1470                 id->filename = xstrdup(options.identity_files[i]);
1471                 TAILQ_INSERT_TAIL(&files, id, next);
1472         }
1473         /* list of keys supported by the agent */
1474         if ((ac = ssh_get_authentication_connection())) {
1475                 for (key = ssh_get_first_identity(ac, &comment, 2);
1476                     key != NULL;
1477                     key = ssh_get_next_identity(ac, &comment, 2)) {
1478                         found = 0;
1479                         TAILQ_FOREACH(id, &files, next) {
1480                                 /* agent keys from the config file are preferred */
1481                                 if (key_equal(key, id->key)) {
1482                                         key_free(key);
1483                                         xfree(comment);
1484                                         TAILQ_REMOVE(&files, id, next);
1485                                         TAILQ_INSERT_TAIL(preferred, id, next);
1486                                         id->ac = ac;
1487                                         found = 1;
1488                                         break;
1489                                 }
1490                         }
1491                         if (!found && !options.identities_only) {
1492                                 id = xcalloc(1, sizeof(*id));
1493                                 id->key = key;
1494                                 id->filename = comment;
1495                                 id->ac = ac;
1496                                 TAILQ_INSERT_TAIL(&agent, id, next);
1497                         }
1498                 }
1499                 /* append remaining agent keys */
1500                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1501                         TAILQ_REMOVE(&agent, id, next);
1502                         TAILQ_INSERT_TAIL(preferred, id, next);
1503                 }
1504                 authctxt->agent = ac;
1505         }
1506         /* append remaining keys from the config file */
1507         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1508                 TAILQ_REMOVE(&files, id, next);
1509                 TAILQ_INSERT_TAIL(preferred, id, next);
1510         }
1511         TAILQ_FOREACH(id, preferred, next) {
1512                 debug2("key: %s (%p)", id->filename, id->key);
1513         }
1514 }
1515
1516 static void
1517 pubkey_cleanup(Authctxt *authctxt)
1518 {
1519         Identity *id;
1520
1521         if (authctxt->agent != NULL)
1522                 ssh_close_authentication_connection(authctxt->agent);
1523         for (id = TAILQ_FIRST(&authctxt->keys); id;
1524             id = TAILQ_FIRST(&authctxt->keys)) {
1525                 TAILQ_REMOVE(&authctxt->keys, id, next);
1526                 if (id->key)
1527                         key_free(id->key);
1528                 if (id->filename)
1529                         xfree(id->filename);
1530                 xfree(id);
1531         }
1532 }
1533
1534 int
1535 userauth_pubkey(Authctxt *authctxt)
1536 {
1537         Identity *id;
1538         int sent = 0;
1539
1540         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1541                 if (id->tried++)
1542                         return (0);
1543                 /* move key to the end of the queue */
1544                 TAILQ_REMOVE(&authctxt->keys, id, next);
1545                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1546                 /*
1547                  * send a test message if we have the public key. for
1548                  * encrypted keys we cannot do this and have to load the
1549                  * private key instead
1550                  */
1551                 if (id->key && id->key->type != KEY_RSA1) {
1552                         debug("Offering public key: %s", id->filename);
1553                         sent = send_pubkey_test(authctxt, id);
1554                 } else if (id->key == NULL) {
1555                         debug("Trying private key: %s", id->filename);
1556                         id->key = load_identity_file(id->filename);
1557                         if (id->key != NULL) {
1558                                 id->isprivate = 1;
1559                                 sent = sign_and_send_pubkey(authctxt, id);
1560                                 key_free(id->key);
1561                                 id->key = NULL;
1562                         }
1563                 }
1564                 if (sent)
1565                         return (sent);
1566         }
1567         return (0);
1568 }
1569
1570 /*
1571  * Send userauth request message specifying keyboard-interactive method.
1572  */
1573 int
1574 userauth_kbdint(Authctxt *authctxt)
1575 {
1576         static int attempt = 0;
1577
1578         if (attempt++ >= options.number_of_password_prompts)
1579                 return 0;
1580         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1581         if (attempt > 1 && !authctxt->info_req_seen) {
1582                 debug3("userauth_kbdint: disable: no info_req_seen");
1583                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1584                 return 0;
1585         }
1586
1587         debug2("userauth_kbdint");
1588         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1589         packet_put_cstring(authctxt->server_user);
1590         packet_put_cstring(authctxt->service);
1591         packet_put_cstring(authctxt->method->name);
1592         packet_put_cstring("");                                 /* lang */
1593         packet_put_cstring(options.kbd_interactive_devices ?
1594             options.kbd_interactive_devices : "");
1595         packet_send();
1596
1597         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1598         return 1;
1599 }
1600
1601 /*
1602  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1603  */
1604 void
1605 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1606 {
1607         Authctxt *authctxt = ctxt;
1608         char *name, *inst, *lang, *prompt, *response;
1609         u_int num_prompts, i;
1610         int echo = 0;
1611
1612         debug2("input_userauth_info_req");
1613
1614         if (authctxt == NULL)
1615                 fatal("input_userauth_info_req: no authentication context");
1616
1617         authctxt->info_req_seen = 1;
1618
1619         name = packet_get_string(NULL);
1620         inst = packet_get_string(NULL);
1621         lang = packet_get_string(NULL);
1622         if (strlen(name) > 0)
1623                 logit("%s", name);
1624         if (strlen(inst) > 0)
1625                 logit("%s", inst);
1626         xfree(name);
1627         xfree(inst);
1628         xfree(lang);
1629
1630         num_prompts = packet_get_int();
1631         /*
1632          * Begin to build info response packet based on prompts requested.
1633          * We commit to providing the correct number of responses, so if
1634          * further on we run into a problem that prevents this, we have to
1635          * be sure and clean this up and send a correct error response.
1636          */
1637         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1638         packet_put_int(num_prompts);
1639
1640         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1641         for (i = 0; i < num_prompts; i++) {
1642                 prompt = packet_get_string(NULL);
1643                 echo = packet_get_char();
1644
1645                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1646
1647                 packet_put_cstring(response);
1648                 memset(response, 0, strlen(response));
1649                 xfree(response);
1650                 xfree(prompt);
1651         }
1652         packet_check_eom(); /* done with parsing incoming message. */
1653
1654         packet_add_padding(64);
1655         packet_send();
1656 }
1657
1658 static int
1659 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1660     u_char *data, u_int datalen)
1661 {
1662         Buffer b;
1663         struct stat st;
1664         pid_t pid;
1665         int to[2], from[2], status, version = 2;
1666
1667         debug2("ssh_keysign called");
1668
1669         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1670                 error("ssh_keysign: no installed: %s", strerror(errno));
1671                 return -1;
1672         }
1673         if (fflush(stdout) != 0)
1674                 error("ssh_keysign: fflush: %s", strerror(errno));
1675         if (pipe(to) < 0) {
1676                 error("ssh_keysign: pipe: %s", strerror(errno));
1677                 return -1;
1678         }
1679         if (pipe(from) < 0) {
1680                 error("ssh_keysign: pipe: %s", strerror(errno));
1681                 return -1;
1682         }
1683         if ((pid = fork()) < 0) {
1684                 error("ssh_keysign: fork: %s", strerror(errno));
1685                 return -1;
1686         }
1687         if (pid == 0) {
1688                 permanently_drop_suid(getuid());
1689                 close(from[0]);
1690                 if (dup2(from[1], STDOUT_FILENO) < 0)
1691                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1692                 close(to[1]);
1693                 if (dup2(to[0], STDIN_FILENO) < 0)
1694                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1695                 close(from[1]);
1696                 close(to[0]);
1697                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1698                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1699                     strerror(errno));
1700         }
1701         close(from[1]);
1702         close(to[0]);
1703
1704         buffer_init(&b);
1705         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1706         buffer_put_string(&b, data, datalen);
1707         if (ssh_msg_send(to[1], version, &b) == -1)
1708                 fatal("ssh_keysign: couldn't send request");
1709
1710         if (ssh_msg_recv(from[0], &b) < 0) {
1711                 error("ssh_keysign: no reply");
1712                 buffer_free(&b);
1713                 return -1;
1714         }
1715         close(from[0]);
1716         close(to[1]);
1717
1718         while (waitpid(pid, &status, 0) < 0)
1719                 if (errno != EINTR)
1720                         break;
1721
1722         if (buffer_get_char(&b) != version) {
1723                 error("ssh_keysign: bad version");
1724                 buffer_free(&b);
1725                 return -1;
1726         }
1727         *sigp = buffer_get_string(&b, lenp);
1728         buffer_free(&b);
1729
1730         return 0;
1731 }
1732
1733 int
1734 userauth_hostbased(Authctxt *authctxt)
1735 {
1736         Key *private = NULL;
1737         Sensitive *sensitive = authctxt->sensitive;
1738         Buffer b;
1739         u_char *signature, *blob;
1740         char *chost, *pkalg, *p, myname[NI_MAXHOST];
1741         const char *service;
1742         u_int blen, slen;
1743         int ok, i, len, found = 0;
1744
1745         /* check for a useful key */
1746         for (i = 0; i < sensitive->nkeys; i++) {
1747                 private = sensitive->keys[i];
1748                 if (private && private->type != KEY_RSA1) {
1749                         found = 1;
1750                         /* we take and free the key */
1751                         sensitive->keys[i] = NULL;
1752                         break;
1753                 }
1754         }
1755         if (!found) {
1756                 debug("No more client hostkeys for hostbased authentication.");
1757                 return 0;
1758         }
1759         if (key_to_blob(private, &blob, &blen) == 0) {
1760                 key_free(private);
1761                 return 0;
1762         }
1763         /* figure out a name for the client host */
1764         p = NULL;
1765         if (packet_connection_is_on_socket())
1766                 p = get_local_name(packet_get_connection_in());
1767         if (p == NULL) {
1768                 if (gethostname(myname, sizeof(myname)) == -1) {
1769                         verbose("userauth_hostbased: gethostname: %s",
1770                             strerror(errno));
1771                 } else
1772                         p = xstrdup(myname);
1773         }
1774         if (p == NULL) {
1775                 error("userauth_hostbased: cannot get local ipaddr/name");
1776                 key_free(private);
1777                 xfree(blob);
1778                 return 0;
1779         }
1780         len = strlen(p) + 2;
1781         xasprintf(&chost, "%s.", p);
1782         debug2("userauth_hostbased: chost %s", chost);
1783         xfree(p);
1784
1785         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1786             authctxt->service;
1787         pkalg = xstrdup(key_ssh_name(private));
1788         buffer_init(&b);
1789         /* construct data */
1790         buffer_put_string(&b, session_id2, session_id2_len);
1791         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1792         buffer_put_cstring(&b, authctxt->server_user);
1793         buffer_put_cstring(&b, service);
1794         buffer_put_cstring(&b, authctxt->method->name);
1795         buffer_put_cstring(&b, pkalg);
1796         buffer_put_string(&b, blob, blen);
1797         buffer_put_cstring(&b, chost);
1798         buffer_put_cstring(&b, authctxt->local_user);
1799 #ifdef DEBUG_PK
1800         buffer_dump(&b);
1801 #endif
1802         if (sensitive->external_keysign)
1803                 ok = ssh_keysign(private, &signature, &slen,
1804                     buffer_ptr(&b), buffer_len(&b));
1805         else
1806                 ok = key_sign(private, &signature, &slen,
1807                     buffer_ptr(&b), buffer_len(&b));
1808         key_free(private);
1809         buffer_free(&b);
1810         if (ok != 0) {
1811                 error("key_sign failed");
1812                 xfree(chost);
1813                 xfree(pkalg);
1814                 xfree(blob);
1815                 return 0;
1816         }
1817         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1818         packet_put_cstring(authctxt->server_user);
1819         packet_put_cstring(authctxt->service);
1820         packet_put_cstring(authctxt->method->name);
1821         packet_put_cstring(pkalg);
1822         packet_put_string(blob, blen);
1823         packet_put_cstring(chost);
1824         packet_put_cstring(authctxt->local_user);
1825         packet_put_string(signature, slen);
1826         memset(signature, 's', slen);
1827         xfree(signature);
1828         xfree(chost);
1829         xfree(pkalg);
1830         xfree(blob);
1831
1832         packet_send();
1833         return 1;
1834 }
1835
1836 #ifdef JPAKE
1837 int
1838 userauth_jpake(Authctxt *authctxt)
1839 {
1840         struct jpake_ctx *pctx;
1841         u_char *x1_proof, *x2_proof;
1842         u_int x1_proof_len, x2_proof_len;
1843         static int attempt = 0; /* XXX share with userauth_password's? */
1844
1845         if (attempt++ >= options.number_of_password_prompts)
1846                 return 0;
1847         if (attempt != 1)
1848                 error("Permission denied, please try again.");
1849
1850         if (authctxt->methoddata != NULL)
1851                 fatal("%s: authctxt->methoddata already set (%p)",
1852                     __func__, authctxt->methoddata);
1853
1854         authctxt->methoddata = pctx = jpake_new();
1855
1856         /*
1857          * Send request immediately, to get the protocol going while
1858          * we do the initial computations.
1859          */
1860         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1861         packet_put_cstring(authctxt->server_user);
1862         packet_put_cstring(authctxt->service);
1863         packet_put_cstring(authctxt->method->name);
1864         packet_send();
1865         packet_write_wait();
1866
1867         jpake_step1(pctx->grp,
1868             &pctx->client_id, &pctx->client_id_len,
1869             &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2,
1870             &x1_proof, &x1_proof_len,
1871             &x2_proof, &x2_proof_len);
1872
1873         JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__));
1874
1875         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1);
1876         packet_put_string(pctx->client_id, pctx->client_id_len);
1877         packet_put_bignum2(pctx->g_x1);
1878         packet_put_bignum2(pctx->g_x2);
1879         packet_put_string(x1_proof, x1_proof_len);
1880         packet_put_string(x2_proof, x2_proof_len);
1881         packet_send();
1882
1883         bzero(x1_proof, x1_proof_len);
1884         bzero(x2_proof, x2_proof_len);
1885         xfree(x1_proof);
1886         xfree(x2_proof);
1887
1888         /* Expect step 1 packet from peer */
1889         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1,
1890             input_userauth_jpake_server_step1);
1891
1892         return 1;
1893 }
1894
1895 void
1896 userauth_jpake_cleanup(Authctxt *authctxt)
1897 {
1898         debug3("%s: clean up", __func__);
1899         if (authctxt->methoddata != NULL) {
1900                 jpake_free(authctxt->methoddata);
1901                 authctxt->methoddata = NULL;
1902         }
1903 }
1904 #endif /* JPAKE */
1905
1906 /* find auth method */
1907
1908 /*
1909  * given auth method name, if configurable options permit this method fill
1910  * in auth_ident field and return true, otherwise return false.
1911  */
1912 static int
1913 authmethod_is_enabled(Authmethod *method)
1914 {
1915         if (method == NULL)
1916                 return 0;
1917         /* return false if options indicate this method is disabled */
1918         if  (method->enabled == NULL || *method->enabled == 0)
1919                 return 0;
1920         /* return false if batch mode is enabled but method needs interactive mode */
1921         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1922                 return 0;
1923         return 1;
1924 }
1925
1926 static Authmethod *
1927 authmethod_lookup(const char *name)
1928 {
1929         Authmethod *method = NULL;
1930         if (name != NULL)
1931                 for (method = authmethods; method->name != NULL; method++)
1932                         if (strcmp(name, method->name) == 0)
1933                                 return method;
1934         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1935         return NULL;
1936 }
1937
1938 /* XXX internal state */
1939 static Authmethod *current = NULL;
1940 static char *supported = NULL;
1941 static char *preferred = NULL;
1942
1943 /*
1944  * Given the authentication method list sent by the server, return the
1945  * next method we should try.  If the server initially sends a nil list,
1946  * use a built-in default list.
1947  */
1948 static Authmethod *
1949 authmethod_get(char *authlist)
1950 {
1951         char *name = NULL;
1952         u_int next;
1953
1954         /* Use a suitable default if we're passed a nil list.  */
1955         if (authlist == NULL || strlen(authlist) == 0)
1956                 authlist = options.preferred_authentications;
1957
1958         if (supported == NULL || strcmp(authlist, supported) != 0) {
1959                 debug3("start over, passed a different list %s", authlist);
1960                 if (supported != NULL)
1961                         xfree(supported);
1962                 supported = xstrdup(authlist);
1963                 preferred = options.preferred_authentications;
1964                 debug3("preferred %s", preferred);
1965                 current = NULL;
1966         } else if (current != NULL && authmethod_is_enabled(current))
1967                 return current;
1968
1969         for (;;) {
1970                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1971                         debug("No more authentication methods to try.");
1972                         current = NULL;
1973                         return NULL;
1974                 }
1975                 preferred += next;
1976                 debug3("authmethod_lookup %s", name);
1977                 debug3("remaining preferred: %s", preferred);
1978                 if ((current = authmethod_lookup(name)) != NULL &&
1979                     authmethod_is_enabled(current)) {
1980                         debug3("authmethod_is_enabled %s", name);
1981                         debug("Next authentication method: %s", name);
1982                         return current;
1983                 }
1984         }
1985 }
1986
1987 static char *
1988 authmethods_get(void)
1989 {
1990         Authmethod *method = NULL;
1991         Buffer b;
1992         char *list;
1993
1994         buffer_init(&b);
1995         for (method = authmethods; method->name != NULL; method++) {
1996                 if (authmethod_is_enabled(method)) {
1997                         if (buffer_len(&b) > 0)
1998                                 buffer_append(&b, ",", 1);
1999                         buffer_append(&b, method->name, strlen(method->name));
2000                 }
2001         }
2002         buffer_append(&b, "\0", 1);
2003         list = xstrdup(buffer_ptr(&b));
2004         buffer_free(&b);
2005         return list;
2006 }
2007