openssh/sshconnect2.c

   1 /*
   2  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  14  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  15  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  16  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  17  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  18  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  19  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  20  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  21  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  22  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  23  */
  24
  25 #include "includes.h"
  26 RCSID("$OpenBSD: sshconnect2.c,v 1.143 2005/10/14 02:17:59 stevesk Exp $");
  27
  28 #include "openbsd-compat/sys-queue.h"
  29
  30 #include "ssh.h"
  31 #include "ssh2.h"
  32 #include "xmalloc.h"
  33 #include "buffer.h"
  34 #include "packet.h"
  35 #include "compat.h"
  36 #include "bufaux.h"
  37 #include "cipher.h"
  38 #include "kex.h"
  39 #include "myproposal.h"
  40 #include "sshconnect.h"
  41 #include "authfile.h"
  42 #include "dh.h"
  43 #include "authfd.h"
  44 #include "log.h"
  45 #include "readconf.h"
  46 #include "misc.h"
  47 #include "match.h"
  48 #include "dispatch.h"
  49 #include "canohost.h"
  50 #include "msg.h"
  51 #include "pathnames.h"
  52
  53 #ifdef GSSAPI
  54 #include "ssh-gss.h"
  55 #endif
  56
  57 /* import */
  58 extern char *client_version_string;
  59 extern char *server_version_string;
  60 extern Options options;
  61 extern Kex *xxx_kex;
  62
  63 /* tty_flag is set in ssh.c. use this in ssh_userauth2 */
  64 /* if it is set then prevent the switch to the null cipher */
  65
  66 extern int tty_flag;
  67
  68 /*
  69  * SSH2 key exchange
  70  */
  71
  72 u_char *session_id2 = NULL;
  73 u_int session_id2_len = 0;
  74
  75 char *xxx_host;
  76 struct sockaddr *xxx_hostaddr;
  77
  78 Kex *xxx_kex = NULL;
  79
  80 static int
  81 verify_host_key_callback(Key *hostkey)
  82 {
  83         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
  84                 fatal("Host key verification failed.");
  85         return 0;
  86 }
  87
  88 void
  89 ssh_kex2(char *host, struct sockaddr *hostaddr)
  90 {
  91         Kex *kex;
  92
  93 #ifdef GSSAPI
  94         char *orig = NULL, *gss = NULL;
  95         int len;
  96         char *gss_host = NULL;
  97 #endif
  98
  99         xxx_host = host;
 100         xxx_hostaddr = hostaddr;
 101
 102 #ifdef GSSAPI
 103         if (options.gss_keyex) {
 104         /* Add the GSSAPI mechanisms currently supported on this client to
 105          * the key exchange algorithm proposal */
 106         orig = myproposal[PROPOSAL_KEX_ALGS];
 107         if (options.gss_trust_dns)
 108                 gss_host = (char *)get_canonical_hostname(1);
 109         else
 110                 gss_host = host;
 111
 112         gss = ssh_gssapi_client_mechanisms(gss_host);
 113         if (gss) {
 114                 debug("Offering GSSAPI proposal: %s", gss);
 115                 len = strlen(orig) + strlen(gss) + 2;
 116                 myproposal[PROPOSAL_KEX_ALGS] = xmalloc(len);
 117                 snprintf(myproposal[PROPOSAL_KEX_ALGS], len, "%s,%s", gss,
 118                     orig);
 119         }
 120         }
 121 #endif
 122
 123         if (options.ciphers == (char *)-1) {
 124                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 125                 options.ciphers = NULL;
 126         }
 127         if (options.ciphers != NULL) {
 128                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 129                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 130         }
 131
 132         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 133             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 134         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 135             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 136         if (options.compression) {
 137                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 138                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 139         } else {
 140                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 141                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 142         }
 143         if (options.macs != NULL) {
 144                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 145                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 146         }
 147         if (options.hostkeyalgorithms != NULL)
 148                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 149                     options.hostkeyalgorithms;
 150
 151 #ifdef GSSAPI
 152         /* If we've got GSSAPI algorithms, then we also support the
 153          * 'null' hostkey, as a last resort */
 154         if (options.gss_keyex && gss) {
 155                 orig = myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
 156                 len = strlen(orig) + sizeof(",null");
 157                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = xmalloc(len);
 158                 snprintf(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS], len,
 159                     "%s,null", orig);
 160         }
 161 #endif
 162
 163         if (options.rekey_limit)
 164                 packet_set_rekey_limit(options.rekey_limit);
 165
 166         /* start key exchange */
 167         kex = kex_setup(myproposal);
 168         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 169         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 170         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 171 #ifdef GSSAPI
 172         kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client;
 173         kex->kex[KEX_GSS_GEX_SHA1] = kexgss_client;
 174 #endif
 175         kex->client_version_string=client_version_string;
 176         kex->server_version_string=server_version_string;
 177         kex->verify_host_key=&verify_host_key_callback;
 178
 179 #ifdef GSSAPI
 180         kex->gss_deleg_creds = options.gss_deleg_creds;
 181         kex->gss_trust_dns = options.gss_trust_dns;
 182         kex->gss_host = gss_host;
 183 #endif
 184
 185         xxx_kex = kex;
 186
 187         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 188
 189         session_id2 = kex->session_id;
 190         session_id2_len = kex->session_id_len;
 191
 192 #ifdef DEBUG_KEXDH
 193         /* send 1st encrypted/maced/compressed message */
 194         packet_start(SSH2_MSG_IGNORE);
 195         packet_put_cstring("markus");
 196         packet_send();
 197         packet_write_wait();
 198 #endif
 199 }
 200
 201 /*
 202  * Authenticate user
 203  */
 204
 205 typedef struct Authctxt Authctxt;
 206 typedef struct Authmethod Authmethod;
 207 typedef struct identity Identity;
 208 typedef struct idlist Idlist;
 209
 210 struct identity {
 211         TAILQ_ENTRY(identity) next;
 212         AuthenticationConnection *ac;   /* set if agent supports key */
 213         Key     *key;                   /* public/private key */
 214         char    *filename;              /* comment for agent-only keys */
 215         int     tried;
 216         int     isprivate;              /* key points to the private key */
 217 };
 218 TAILQ_HEAD(idlist, identity);
 219
 220 struct Authctxt {
 221         const char *server_user;
 222         const char *local_user;
 223         const char *host;
 224         const char *service;
 225         Authmethod *method;
 226         int success;
 227         char *authlist;
 228         /* pubkey */
 229         Idlist keys;
 230         AuthenticationConnection *agent;
 231         /* hostbased */
 232         Sensitive *sensitive;
 233         /* kbd-interactive */
 234         int info_req_seen;
 235         /* generic */
 236         void *methoddata;
 237 };
 238 struct Authmethod {
 239         char    *name;          /* string to compare against server's list */
 240         int     (*userauth)(Authctxt *authctxt);
 241         int     *enabled;       /* flag in option struct that enables method */
 242         int     *batch_flag;    /* flag in option struct that disables method */
 243 };
 244
 245 void    input_userauth_success(int, u_int32_t, void *);
 246 void    input_userauth_failure(int, u_int32_t, void *);
 247 void    input_userauth_banner(int, u_int32_t, void *);
 248 void    input_userauth_error(int, u_int32_t, void *);
 249 void    input_userauth_info_req(int, u_int32_t, void *);
 250 void    input_userauth_pk_ok(int, u_int32_t, void *);
 251 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 252
 253 int     userauth_none(Authctxt *);
 254 int     userauth_pubkey(Authctxt *);
 255 int     userauth_passwd(Authctxt *);
 256 int     userauth_kbdint(Authctxt *);
 257 int     userauth_hostbased(Authctxt *);
 258 int     userauth_kerberos(Authctxt *);
 259
 260 #ifdef GSSAPI
 261 int     userauth_external(Authctxt *authctxt);
 262 int     userauth_gssapi(Authctxt *authctxt);
 263 int     userauth_gssapi_with_mic(Authctxt *authctxt);
 264 int     userauth_gssapi_without_mic(Authctxt *authctxt);
 265 void    input_gssapi_response(int type, u_int32_t, void *);
 266 void    input_gssapi_token(int type, u_int32_t, void *);
 267 void    input_gssapi_hash(int type, u_int32_t, void *);
 268 void    input_gssapi_error(int, u_int32_t, void *);
 269 void    input_gssapi_errtok(int, u_int32_t, void *);
 270 int     userauth_gsskeyex(Authctxt *authctxt);
 271 #endif
 272
 273 void    userauth(Authctxt *, char *);
 274
 275 static int sign_and_send_pubkey(Authctxt *, Identity *);
 276 static void pubkey_prepare(Authctxt *);
 277 static void pubkey_cleanup(Authctxt *);
 278 static Key *load_identity_file(char *);
 279
 280 static Authmethod *authmethod_get(char *authlist);
 281 static Authmethod *authmethod_lookup(const char *name);
 282 static char *authmethods_get(void);
 283
 284 Authmethod authmethods[] = {
 285 #ifdef GSSAPI
 286         {"gssapi-keyex",
 287                 userauth_gsskeyex,
 288                 &options.gss_authentication,
 289                 NULL},
 290         {"external-keyx",
 291                 userauth_external,
 292                 &options.gss_authentication,
 293                 NULL},
 294         {"gssapi-with-mic",
 295                 userauth_gssapi,
 296                 &options.gss_authentication,
 297                 NULL},
 298         {"gssapi",
 299                 userauth_gssapi,
 300                 &options.gss_authentication,
 301                 NULL},
 302 #endif
 303         {"hostbased",
 304                 userauth_hostbased,
 305                 &options.hostbased_authentication,
 306                 NULL},
 307         {"publickey",
 308                 userauth_pubkey,
 309                 &options.pubkey_authentication,
 310                 NULL},
 311         {"keyboard-interactive",
 312                 userauth_kbdint,
 313                 &options.kbd_interactive_authentication,
 314                 &options.batch_mode},
 315         {"password",
 316                 userauth_passwd,
 317                 &options.password_authentication,
 318                 &options.batch_mode},
 319         {"none",
 320                 userauth_none,
 321                 NULL,
 322                 NULL},
 323         {NULL, NULL, NULL, NULL}
 324 };
 325
 326 void
 327 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 328     Sensitive *sensitive)
 329 {
 330         Authctxt authctxt;
 331         int type;
 332
 333         if (options.challenge_response_authentication)
 334                 options.kbd_interactive_authentication = 1;
 335
 336         packet_start(SSH2_MSG_SERVICE_REQUEST);
 337         packet_put_cstring("ssh-userauth");
 338         packet_send();
 339         debug("SSH2_MSG_SERVICE_REQUEST sent");
 340         packet_write_wait();
 341         type = packet_read();
 342         if (type != SSH2_MSG_SERVICE_ACCEPT)
 343                 fatal("Server denied authentication request: %d", type);
 344         if (packet_remaining() > 0) {
 345                 char *reply = packet_get_string(NULL);
 346                 debug2("service_accept: %s", reply);
 347                 xfree(reply);
 348         } else {
 349                 debug2("buggy server: service_accept w/o service");
 350         }
 351         packet_check_eom();
 352         debug("SSH2_MSG_SERVICE_ACCEPT received");
 353
 354         if (options.preferred_authentications == NULL)
 355                 options.preferred_authentications = authmethods_get();
 356
 357         /* setup authentication context */
 358         memset(&authctxt, 0, sizeof(authctxt));
 359         pubkey_prepare(&authctxt);
 360         authctxt.server_user = server_user;
 361         authctxt.local_user = local_user;
 362         authctxt.host = host;
 363         authctxt.service = "ssh-connection";            /* service name */
 364         authctxt.success = 0;
 365         authctxt.method = authmethod_lookup("none");
 366         authctxt.authlist = NULL;
 367         authctxt.methoddata = NULL;
 368         authctxt.sensitive = sensitive;
 369         authctxt.info_req_seen = 0;
 370         if (authctxt.method == NULL)
 371                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 372
 373         /* initial userauth request */
 374         userauth_none(&authctxt);
 375
 376         dispatch_init(&input_userauth_error);
 377         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 378         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 379         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 380         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 381
 382         pubkey_cleanup(&authctxt);
 383         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 384         if ((options.none_switch == 1) && (options.none_enabled == 1) && !tty_flag) /* no null on tty sessions */
 385         {
 386                 debug("Requesting none rekeying...");
 387                 myproposal[PROPOSAL_ENC_ALGS_STOC] = "none";
 388                 myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none";
 389                 kex_prop2buf(&xxx_kex->my,myproposal);
 390                 packet_request_rekeying();
 391                 fprintf(stderr, "WARNING: ENABLED NULL CIPHER\n");
 392         }
 393         debug("Authentication succeeded (%s).", authctxt.method->name);
 394 }
 395
 396 void
 397 userauth(Authctxt *authctxt, char *authlist)
 398 {
 399         if (authctxt->methoddata) {
 400                 xfree(authctxt->methoddata);
 401                 authctxt->methoddata = NULL;
 402         }
 403         if (authlist == NULL) {
 404                 authlist = authctxt->authlist;
 405         } else {
 406                 if (authctxt->authlist)
 407                         xfree(authctxt->authlist);
 408                 authctxt->authlist = authlist;
 409         }
 410         for (;;) {
 411                 Authmethod *method = authmethod_get(authlist);
 412                 if (method == NULL)
 413                         fatal("Permission denied (%s).", authlist);
 414                 authctxt->method = method;
 415
 416                 /* reset the per method handler */
 417                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 418                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 419
 420                 /* and try new method */
 421                 if (method->userauth(authctxt) != 0) {
 422                         debug2("we sent a %s packet, wait for reply", method->name);
 423                         break;
 424                 } else {
 425                         debug2("we did not send a packet, disable method");
 426                         method->enabled = NULL;
 427                 }
 428         }
 429 }
 430
 431 void
 432 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 433 {
 434         fatal("input_userauth_error: bad message during authentication: "
 435             "type %d", type);
 436 }
 437
 438 void
 439 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 440 {
 441         char *msg, *lang;
 442
 443         debug3("input_userauth_banner");
 444         msg = packet_get_string(NULL);
 445         lang = packet_get_string(NULL);
 446         if (options.log_level > SYSLOG_LEVEL_QUIET)
 447                 fprintf(stderr, "%s", msg);
 448         xfree(msg);
 449         xfree(lang);
 450 }
 451
 452 void
 453 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 454 {
 455         Authctxt *authctxt = ctxt;
 456         if (authctxt == NULL)
 457                 fatal("input_userauth_success: no authentication context");
 458         if (authctxt->authlist) {
 459                 xfree(authctxt->authlist);
 460                 authctxt->authlist = NULL;
 461         }
 462         if (authctxt->methoddata) {
 463                 xfree(authctxt->methoddata);
 464                 authctxt->methoddata = NULL;
 465         }
 466         authctxt->success = 1;                  /* break out */
 467 }
 468
 469 void
 470 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 471 {
 472         Authctxt *authctxt = ctxt;
 473         char *authlist = NULL;
 474         int partial;
 475
 476         if (authctxt == NULL)
 477                 fatal("input_userauth_failure: no authentication context");
 478
 479         authlist = packet_get_string(NULL);
 480         partial = packet_get_char();
 481         packet_check_eom();
 482
 483         if (partial != 0)
 484                 logit("Authenticated with partial success.");
 485         debug("Authentications that can continue: %s", authlist);
 486
 487         userauth(authctxt, authlist);
 488 }
 489 void
 490 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 491 {
 492         Authctxt *authctxt = ctxt;
 493         Key *key = NULL;
 494         Identity *id = NULL;
 495         Buffer b;
 496         int pktype, sent = 0;
 497         u_int alen, blen;
 498         char *pkalg, *fp;
 499         u_char *pkblob;
 500
 501         if (authctxt == NULL)
 502                 fatal("input_userauth_pk_ok: no authentication context");
 503         if (datafellows & SSH_BUG_PKOK) {
 504                 /* this is similar to SSH_BUG_PKAUTH */
 505                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 506                 pkblob = packet_get_string(&blen);
 507                 buffer_init(&b);
 508                 buffer_append(&b, pkblob, blen);
 509                 pkalg = buffer_get_string(&b, &alen);
 510                 buffer_free(&b);
 511         } else {
 512                 pkalg = packet_get_string(&alen);
 513                 pkblob = packet_get_string(&blen);
 514         }
 515         packet_check_eom();
 516
 517         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 518
 519         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 520                 debug("unknown pkalg %s", pkalg);
 521                 goto done;
 522         }
 523         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 524                 debug("no key from blob. pkalg %s", pkalg);
 525                 goto done;
 526         }
 527         if (key->type != pktype) {
 528                 error("input_userauth_pk_ok: type mismatch "
 529                     "for decoded key (received %d, expected %d)",
 530                     key->type, pktype);
 531                 goto done;
 532         }
 533         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 534         debug2("input_userauth_pk_ok: fp %s", fp);
 535         xfree(fp);
 536
 537         /*
 538          * search keys in the reverse order, because last candidate has been
 539          * moved to the end of the queue.  this also avoids confusion by
 540          * duplicate keys
 541          */
 542         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 543                 if (key_equal(key, id->key)) {
 544                         sent = sign_and_send_pubkey(authctxt, id);
 545                         break;
 546                 }
 547         }
 548 done:
 549         if (key != NULL)
 550                 key_free(key);
 551         xfree(pkalg);
 552         xfree(pkblob);
 553
 554         /* try another method if we did not send a packet */
 555         if (sent == 0)
 556                 userauth(authctxt, NULL);
 557 }
 558
 559 #ifdef GSSAPI
 560 int
 561 userauth_gssapi(Authctxt *authctxt)
 562 {
 563         Gssctxt *gssctxt = NULL;
 564         static gss_OID_set gss_supported = NULL;
 565         static u_int mech = 0;
 566         OM_uint32 min;
 567         int ok = 0;
 568         char *gss_host = NULL;
 569
 570         if (!options.gss_authentication) {
 571                 verbose("GSSAPI authentication disabled.");
 572                 return 0;
 573         }
 574
 575         if (options.gss_trust_dns)
 576                 gss_host = (char *)get_canonical_hostname(1);
 577         else
 578                 gss_host = (char *)authctxt->host;
 579
 580         /* Try one GSSAPI method at a time, rather than sending them all at
 581          * once. */
 582
 583         if (gss_supported == NULL)
 584                 gss_indicate_mechs(&min, &gss_supported);
 585
 586         /* Check to see if the mechanism is usable before we offer it */
 587         while (mech < gss_supported->count && !ok) {
 588                 if (gssctxt)
 589                         ssh_gssapi_delete_ctx(&gssctxt);
 590                 ssh_gssapi_build_ctx(&gssctxt);
 591                 ssh_gssapi_set_oid(gssctxt, &gss_supported->elements[mech]);
 592
 593                 /* My DER encoding requires length<128 */
 594                 if (gss_supported->elements[mech].length < 128 &&
 595                     ssh_gssapi_check_mechanism(&gss_supported->elements[mech],
 596                                                gss_host) &&
 597                     !GSS_ERROR(ssh_gssapi_import_name(gssctxt,
 598                                                       gss_host))) {
 599                         ok = 1; /* Mechanism works */
 600                 } else {
 601                         mech++;
 602                 }
 603         }
 604
 605         if (!ok)
 606                 return 0;
 607
 608         authctxt->methoddata=(void *)gssctxt;
 609
 610         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 611         packet_put_cstring(authctxt->server_user);
 612         packet_put_cstring(authctxt->service);
 613         packet_put_cstring(authctxt->method->name);
 614
 615         packet_put_int(1);
 616
 617         packet_put_int((gss_supported->elements[mech].length) + 2);
 618         packet_put_char(SSH_GSS_OIDTYPE);
 619         packet_put_char(gss_supported->elements[mech].length);
 620         packet_put_raw(gss_supported->elements[mech].elements,
 621             gss_supported->elements[mech].length);
 622
 623         packet_send();
 624
 625         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 626         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 627         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 628         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 629
 630         mech++; /* Move along to next candidate */
 631
 632         return 1;
 633 }
 634
 635 static OM_uint32
 636 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 637 {
 638         Authctxt *authctxt = ctxt;
 639         Gssctxt *gssctxt = authctxt->methoddata;
 640         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 641         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 642         gss_buffer_desc gssbuf;
 643         OM_uint32 status, ms, flags;
 644         Buffer b;
 645
 646         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 647             recv_tok, &send_tok, &flags);
 648
 649         if (send_tok.length > 0) {
 650                 if (GSS_ERROR(status))
 651                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 652                 else
 653                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 654
 655                 packet_put_string(send_tok.value, send_tok.length);
 656                 packet_send();
 657                 gss_release_buffer(&ms, &send_tok);
 658         }
 659
 660         if (status == GSS_S_COMPLETE) {
 661                 /* send either complete or MIC, depending on mechanism */
 662                 if (strcmp(authctxt->method->name,"gssapi")==0 ||
 663                     (!(flags & GSS_C_INTEG_FLAG))) {
 664                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 665                         packet_send();
 666                 } else {
 667                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 668                             authctxt->service, "gssapi-with-mic");
 669
 670                         gssbuf.value = buffer_ptr(&b);
 671                         gssbuf.length = buffer_len(&b);
 672
 673                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 674
 675                         if (!GSS_ERROR(status)) {
 676                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 677                                 packet_put_string(mic.value, mic.length);
 678
 679                                 packet_send();
 680                         }
 681
 682                         buffer_free(&b);
 683                         gss_release_buffer(&ms, &mic);
 684                 }
 685         }
 686
 687         return status;
 688 }
 689
 690 void
 691 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 692 {
 693         Authctxt *authctxt = ctxt;
 694         Gssctxt *gssctxt;
 695         unsigned int oidlen;
 696         unsigned char *oidv;
 697
 698         if (authctxt == NULL)
 699                 fatal("input_gssapi_response: no authentication context");
 700         gssctxt = authctxt->methoddata;
 701
 702         /* Setup our OID */
 703         oidv = packet_get_string(&oidlen);
 704
 705         if (oidlen <= 2 ||
 706             oidv[0] != SSH_GSS_OIDTYPE ||
 707             oidv[1] != oidlen - 2) {
 708                 xfree(oidv);
 709                 debug("Badly encoded mechanism OID received");
 710                 userauth(authctxt, NULL);
 711                 return;
 712         }
 713
 714         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 715                 fatal("Server returned different OID than expected");
 716
 717         packet_check_eom();
 718
 719         xfree(oidv);
 720
 721         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 722                 /* Start again with next method on list */
 723                 debug("Trying to start again");
 724                 userauth(authctxt, NULL);
 725                 return;
 726         }
 727 }
 728
 729 void
 730 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 731 {
 732         Authctxt *authctxt = ctxt;
 733         gss_buffer_desc recv_tok;
 734         OM_uint32 status;
 735         u_int slen;
 736
 737         if (authctxt == NULL)
 738                 fatal("input_gssapi_response: no authentication context");
 739
 740         recv_tok.value = packet_get_string(&slen);
 741         recv_tok.length = slen; /* safe typecast */
 742
 743         packet_check_eom();
 744
 745         status = process_gssapi_token(ctxt, &recv_tok);
 746
 747         xfree(recv_tok.value);
 748
 749         if (GSS_ERROR(status)) {
 750                 /* Start again with the next method in the list */
 751                 userauth(authctxt, NULL);
 752                 return;
 753         }
 754 }
 755
 756 void
 757 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 758 {
 759         Authctxt *authctxt = ctxt;
 760         Gssctxt *gssctxt;
 761         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 762         gss_buffer_desc recv_tok;
 763         OM_uint32 status, ms;
 764         u_int len;
 765
 766         if (authctxt == NULL)
 767                 fatal("input_gssapi_response: no authentication context");
 768         gssctxt = authctxt->methoddata;
 769
 770         recv_tok.value = packet_get_string(&len);
 771         recv_tok.length = len;
 772
 773         packet_check_eom();
 774
 775         /* Stick it into GSSAPI and see what it says */
 776         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 777             &recv_tok, &send_tok, NULL);
 778
 779         xfree(recv_tok.value);
 780         gss_release_buffer(&ms, &send_tok);
 781
 782         /* Server will be returning a failed packet after this one */
 783 }
 784
 785 void
 786 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 787 {
 788         OM_uint32 maj, min;
 789         char *msg;
 790         char *lang;
 791
 792         maj=packet_get_int();
 793         min=packet_get_int();
 794         msg=packet_get_string(NULL);
 795         lang=packet_get_string(NULL);
 796
 797         packet_check_eom();
 798
 799         debug("Server GSSAPI Error:\n%s", msg);
 800         xfree(msg);
 801         xfree(lang);
 802 }
 803
 804 #ifdef GSI
 805 extern
 806 const gss_OID_desc * const              gss_mech_globus_gssapi_openssl;
 807 #define is_gsi_oid(oid) \
 808   (oid->length == gss_mech_globus_gssapi_openssl->length && \
 809    (memcmp(oid->elements, gss_mech_globus_gssapi_openssl->elements, \
 810            oid->length) == 0))
 811 #endif
 812
 813 int
 814 userauth_external(Authctxt *authctxt)
 815 {
 816         static int attempt = 0;
 817
 818         if (attempt++ >= 1)
 819                 return 0;
 820
 821         /* The client MUST NOT try this method if initial key exchange
 822            was not performed using a GSSAPI-based key exchange
 823            method. */
 824         if (gss_kex_context == NULL) {
 825                 debug2("gsskex not performed, skipping external-keyx");
 826                 return 0;
 827         }
 828
 829         debug2("userauth_external");
 830         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 831 #ifdef GSI
 832         if (options.implicit && is_gsi_oid(gss_kex_context->oid)) {
 833         packet_put_cstring("");
 834         } else {
 835 #endif
 836         packet_put_cstring(authctxt->server_user);
 837 #ifdef GSI
 838         }
 839 #endif
 840         packet_put_cstring(authctxt->service);
 841         packet_put_cstring(authctxt->method->name);
 842         packet_send();
 843         packet_write_wait();
 844         return 1;
 845 }
 846 int
 847 userauth_gsskeyex(Authctxt *authctxt)
 848 {
 849         Buffer b;
 850         gss_buffer_desc gssbuf;
 851         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 852         OM_uint32 ms;
 853
 854         static int attempt = 0;
 855         if (attempt++ >= 1)
 856                 return (0);
 857
 858         if (gss_kex_context == NULL) {
 859                 debug("No valid Key exchange context");
 860                 return (0);
 861         }
 862
 863 #ifdef GSI
 864         if (options.implicit && is_gsi_oid(gss_kex_context->oid)) {
 865         ssh_gssapi_buildmic(&b, "", authctxt->service, "gssapi-keyex");
 866         } else {
 867 #endif
 868         ssh_gssapi_buildmic(&b, authctxt->server_user, authctxt->service,
 869             "gssapi-keyex");
 870 #ifdef GSI
 871         }
 872 #endif
 873
 874         gssbuf.value = buffer_ptr(&b);
 875         gssbuf.length = buffer_len(&b);
 876
 877         if (GSS_ERROR(ssh_gssapi_sign(gss_kex_context, &gssbuf, &mic))) {
 878                 buffer_free(&b);
 879                 return (0);
 880         }
 881
 882         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 883 #ifdef GSI
 884         if (options.implicit && is_gsi_oid(gss_kex_context->oid)) {
 885         packet_put_cstring("");
 886         } else {
 887 #endif
 888         packet_put_cstring(authctxt->server_user);
 889 #ifdef GSI
 890         }
 891 #endif
 892         packet_put_cstring(authctxt->service);
 893         packet_put_cstring(authctxt->method->name);
 894         packet_put_string(mic.value, mic.length);
 895         packet_send();
 896
 897         buffer_free(&b);
 898         gss_release_buffer(&ms, &mic);
 899
 900         return (1);
 901 }
 902
 903 #endif /* GSSAPI */
 904
 905 int
 906 userauth_none(Authctxt *authctxt)
 907 {
 908         /* initial userauth request */
 909         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 910         packet_put_cstring(authctxt->server_user);
 911         packet_put_cstring(authctxt->service);
 912         packet_put_cstring(authctxt->method->name);
 913         packet_send();
 914         return 1;
 915 }
 916
 917 int
 918 userauth_passwd(Authctxt *authctxt)
 919 {
 920         static int attempt = 0;
 921         char prompt[150];
 922         char *password;
 923
 924         if (attempt++ >= options.number_of_password_prompts)
 925                 return 0;
 926
 927         if (attempt != 1)
 928                 error("Permission denied, please try again.");
 929
 930         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 931             authctxt->server_user, authctxt->host);
 932         password = read_passphrase(prompt, 0);
 933         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 934         packet_put_cstring(authctxt->server_user);
 935         packet_put_cstring(authctxt->service);
 936         packet_put_cstring(authctxt->method->name);
 937         packet_put_char(0);
 938         packet_put_cstring(password);
 939         memset(password, 0, strlen(password));
 940         xfree(password);
 941         packet_add_padding(64);
 942         packet_send();
 943
 944         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 945             &input_userauth_passwd_changereq);
 946
 947         return 1;
 948 }
 949 /*
 950  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 951  */
 952 void
 953 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 954 {
 955         Authctxt *authctxt = ctxt;
 956         char *info, *lang, *password = NULL, *retype = NULL;
 957         char prompt[150];
 958
 959         debug2("input_userauth_passwd_changereq");
 960
 961         if (authctxt == NULL)
 962                 fatal("input_userauth_passwd_changereq: "
 963                     "no authentication context");
 964
 965         info = packet_get_string(NULL);
 966         lang = packet_get_string(NULL);
 967         if (strlen(info) > 0)
 968                 logit("%s", info);
 969         xfree(info);
 970         xfree(lang);
 971         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 972         packet_put_cstring(authctxt->server_user);
 973         packet_put_cstring(authctxt->service);
 974         packet_put_cstring(authctxt->method->name);
 975         packet_put_char(1);                     /* additional info */
 976         snprintf(prompt, sizeof(prompt),
 977             "Enter %.30s@%.128s's old password: ",
 978             authctxt->server_user, authctxt->host);
 979         password = read_passphrase(prompt, 0);
 980         packet_put_cstring(password);
 981         memset(password, 0, strlen(password));
 982         xfree(password);
 983         password = NULL;
 984         while (password == NULL) {
 985                 snprintf(prompt, sizeof(prompt),
 986                     "Enter %.30s@%.128s's new password: ",
 987                     authctxt->server_user, authctxt->host);
 988                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 989                 if (password == NULL) {
 990                         /* bail out */
 991                         return;
 992                 }
 993                 snprintf(prompt, sizeof(prompt),
 994                     "Retype %.30s@%.128s's new password: ",
 995                     authctxt->server_user, authctxt->host);
 996                 retype = read_passphrase(prompt, 0);
 997                 if (strcmp(password, retype) != 0) {
 998                         memset(password, 0, strlen(password));
 999                         xfree(password);
1000                         logit("Mismatch; try again, EOF to quit.");
1001                         password = NULL;
1002                 }
1003                 memset(retype, 0, strlen(retype));
1004                 xfree(retype);
1005         }
1006         packet_put_cstring(password);
1007         memset(password, 0, strlen(password));
1008         xfree(password);
1009         packet_add_padding(64);
1010         packet_send();
1011
1012         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
1013             &input_userauth_passwd_changereq);
1014 }
1015
1016 static int
1017 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
1018     u_char *data, u_int datalen)
1019 {
1020         Key *prv;
1021         int ret;
1022
1023         /* the agent supports this key */
1024         if (id->ac)
1025                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1026                     data, datalen));
1027         /*
1028          * we have already loaded the private key or
1029          * the private key is stored in external hardware
1030          */
1031         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1032                 return (key_sign(id->key, sigp, lenp, data, datalen));
1033         /* load the private key from the file */
1034         if ((prv = load_identity_file(id->filename)) == NULL)
1035                 return (-1);
1036         ret = key_sign(prv, sigp, lenp, data, datalen);
1037         key_free(prv);
1038         return (ret);
1039 }
1040
1041 static int
1042 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1043 {
1044         Buffer b;
1045         u_char *blob, *signature;
1046         u_int bloblen, slen;
1047         u_int skip = 0;
1048         int ret = -1;
1049         int have_sig = 1;
1050
1051         debug3("sign_and_send_pubkey");
1052
1053         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1054                 /* we cannot handle this key */
1055                 debug3("sign_and_send_pubkey: cannot handle key");
1056                 return 0;
1057         }
1058         /* data to be signed */
1059         buffer_init(&b);
1060         if (datafellows & SSH_OLD_SESSIONID) {
1061                 buffer_append(&b, session_id2, session_id2_len);
1062                 skip = session_id2_len;
1063         } else {
1064                 buffer_put_string(&b, session_id2, session_id2_len);
1065                 skip = buffer_len(&b);
1066         }
1067         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1068         buffer_put_cstring(&b, authctxt->server_user);
1069         buffer_put_cstring(&b,
1070             datafellows & SSH_BUG_PKSERVICE ?
1071             "ssh-userauth" :
1072             authctxt->service);
1073         if (datafellows & SSH_BUG_PKAUTH) {
1074                 buffer_put_char(&b, have_sig);
1075         } else {
1076                 buffer_put_cstring(&b, authctxt->method->name);
1077                 buffer_put_char(&b, have_sig);
1078                 buffer_put_cstring(&b, key_ssh_name(id->key));
1079         }
1080         buffer_put_string(&b, blob, bloblen);
1081
1082         /* generate signature */
1083         ret = identity_sign(id, &signature, &slen,
1084             buffer_ptr(&b), buffer_len(&b));
1085         if (ret == -1) {
1086                 xfree(blob);
1087                 buffer_free(&b);
1088                 return 0;
1089         }
1090 #ifdef DEBUG_PK
1091         buffer_dump(&b);
1092 #endif
1093         if (datafellows & SSH_BUG_PKSERVICE) {
1094                 buffer_clear(&b);
1095                 buffer_append(&b, session_id2, session_id2_len);
1096                 skip = session_id2_len;
1097                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1098                 buffer_put_cstring(&b, authctxt->server_user);
1099                 buffer_put_cstring(&b, authctxt->service);
1100                 buffer_put_cstring(&b, authctxt->method->name);
1101                 buffer_put_char(&b, have_sig);
1102                 if (!(datafellows & SSH_BUG_PKAUTH))
1103                         buffer_put_cstring(&b, key_ssh_name(id->key));
1104                 buffer_put_string(&b, blob, bloblen);
1105         }
1106         xfree(blob);
1107
1108         /* append signature */
1109         buffer_put_string(&b, signature, slen);
1110         xfree(signature);
1111
1112         /* skip session id and packet type */
1113         if (buffer_len(&b) < skip + 1)
1114                 fatal("userauth_pubkey: internal error");
1115         buffer_consume(&b, skip + 1);
1116
1117         /* put remaining data from buffer into packet */
1118         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1119         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1120         buffer_free(&b);
1121         packet_send();
1122
1123         return 1;
1124 }
1125
1126 static int
1127 send_pubkey_test(Authctxt *authctxt, Identity *id)
1128 {
1129         u_char *blob;
1130         u_int bloblen, have_sig = 0;
1131
1132         debug3("send_pubkey_test");
1133
1134         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1135                 /* we cannot handle this key */
1136                 debug3("send_pubkey_test: cannot handle key");
1137                 return 0;
1138         }
1139         /* register callback for USERAUTH_PK_OK message */
1140         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1141
1142         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1143         packet_put_cstring(authctxt->server_user);
1144         packet_put_cstring(authctxt->service);
1145         packet_put_cstring(authctxt->method->name);
1146         packet_put_char(have_sig);
1147         if (!(datafellows & SSH_BUG_PKAUTH))
1148                 packet_put_cstring(key_ssh_name(id->key));
1149         packet_put_string(blob, bloblen);
1150         xfree(blob);
1151         packet_send();
1152         return 1;
1153 }
1154
1155 static Key *
1156 load_identity_file(char *filename)
1157 {
1158         Key *private;
1159         char prompt[300], *passphrase;
1160         int quit, i;
1161         struct stat st;
1162
1163         if (stat(filename, &st) < 0) {
1164                 debug3("no such identity: %s", filename);
1165                 return NULL;
1166         }
1167         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL);
1168         if (private == NULL) {
1169                 if (options.batch_mode)
1170                         return NULL;
1171                 snprintf(prompt, sizeof prompt,
1172                     "Enter passphrase for key '%.100s': ", filename);
1173                 for (i = 0; i < options.number_of_password_prompts; i++) {
1174                         passphrase = read_passphrase(prompt, 0);
1175                         if (strcmp(passphrase, "") != 0) {
1176                                 private = key_load_private_type(KEY_UNSPEC, filename,
1177                                     passphrase, NULL);
1178                                 quit = 0;
1179                         } else {
1180                                 debug2("no passphrase given, try next key");
1181                                 quit = 1;
1182                         }
1183                         memset(passphrase, 0, strlen(passphrase));
1184                         xfree(passphrase);
1185                         if (private != NULL || quit)
1186                                 break;
1187                         debug2("bad passphrase given, try again...");
1188                 }
1189         }
1190         return private;
1191 }
1192
1193 /*
1194  * try keys in the following order:
1195  *      1. agent keys that are found in the config file
1196  *      2. other agent keys
1197  *      3. keys that are only listed in the config file
1198  */
1199 static void
1200 pubkey_prepare(Authctxt *authctxt)
1201 {
1202         Identity *id;
1203         Idlist agent, files, *preferred;
1204         Key *key;
1205         AuthenticationConnection *ac;
1206         char *comment;
1207         int i, found;
1208
1209         TAILQ_INIT(&agent);     /* keys from the agent */
1210         TAILQ_INIT(&files);     /* keys from the config file */
1211         preferred = &authctxt->keys;
1212         TAILQ_INIT(preferred);  /* preferred order of keys */
1213
1214         /* list of keys stored in the filesystem */
1215         for (i = 0; i < options.num_identity_files; i++) {
1216                 key = options.identity_keys[i];
1217                 if (key && key->type == KEY_RSA1)
1218                         continue;
1219                 options.identity_keys[i] = NULL;
1220                 id = xmalloc(sizeof(*id));
1221                 memset(id, 0, sizeof(*id));
1222                 id->key = key;
1223                 id->filename = xstrdup(options.identity_files[i]);
1224                 TAILQ_INSERT_TAIL(&files, id, next);
1225         }
1226         /* list of keys supported by the agent */
1227         if ((ac = ssh_get_authentication_connection())) {
1228                 for (key = ssh_get_first_identity(ac, &comment, 2);
1229                     key != NULL;
1230                     key = ssh_get_next_identity(ac, &comment, 2)) {
1231                         found = 0;
1232                         TAILQ_FOREACH(id, &files, next) {
1233                                 /* agent keys from the config file are preferred */
1234                                 if (key_equal(key, id->key)) {
1235                                         key_free(key);
1236                                         xfree(comment);
1237                                         TAILQ_REMOVE(&files, id, next);
1238                                         TAILQ_INSERT_TAIL(preferred, id, next);
1239                                         id->ac = ac;
1240                                         found = 1;
1241                                         break;
1242                                 }
1243                         }
1244                         if (!found && !options.identities_only) {
1245                                 id = xmalloc(sizeof(*id));
1246                                 memset(id, 0, sizeof(*id));
1247                                 id->key = key;
1248                                 id->filename = comment;
1249                                 id->ac = ac;
1250                                 TAILQ_INSERT_TAIL(&agent, id, next);
1251                         }
1252                 }
1253                 /* append remaining agent keys */
1254                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1255                         TAILQ_REMOVE(&agent, id, next);
1256                         TAILQ_INSERT_TAIL(preferred, id, next);
1257                 }
1258                 authctxt->agent = ac;
1259         }
1260         /* append remaining keys from the config file */
1261         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1262                 TAILQ_REMOVE(&files, id, next);
1263                 TAILQ_INSERT_TAIL(preferred, id, next);
1264         }
1265         TAILQ_FOREACH(id, preferred, next) {
1266                 debug2("key: %s (%p)", id->filename, id->key);
1267         }
1268 }
1269
1270 static void
1271 pubkey_cleanup(Authctxt *authctxt)
1272 {
1273         Identity *id;
1274
1275         if (authctxt->agent != NULL)
1276                 ssh_close_authentication_connection(authctxt->agent);
1277         for (id = TAILQ_FIRST(&authctxt->keys); id;
1278             id = TAILQ_FIRST(&authctxt->keys)) {
1279                 TAILQ_REMOVE(&authctxt->keys, id, next);
1280                 if (id->key)
1281                         key_free(id->key);
1282                 if (id->filename)
1283                         xfree(id->filename);
1284                 xfree(id);
1285         }
1286 }
1287
1288 int
1289 userauth_pubkey(Authctxt *authctxt)
1290 {
1291         Identity *id;
1292         int sent = 0;
1293
1294         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1295                 if (id->tried++)
1296                         return (0);
1297                 /* move key to the end of the queue */
1298                 TAILQ_REMOVE(&authctxt->keys, id, next);
1299                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1300                 /*
1301                  * send a test message if we have the public key. for
1302                  * encrypted keys we cannot do this and have to load the
1303                  * private key instead
1304                  */
1305                 if (id->key && id->key->type != KEY_RSA1) {
1306                         debug("Offering public key: %s", id->filename);
1307                         sent = send_pubkey_test(authctxt, id);
1308                 } else if (id->key == NULL) {
1309                         debug("Trying private key: %s", id->filename);
1310                         id->key = load_identity_file(id->filename);
1311                         if (id->key != NULL) {
1312                                 id->isprivate = 1;
1313                                 sent = sign_and_send_pubkey(authctxt, id);
1314                                 key_free(id->key);
1315                                 id->key = NULL;
1316                         }
1317                 }
1318                 if (sent)
1319                         return (sent);
1320         }
1321         return (0);
1322 }
1323
1324 /*
1325  * Send userauth request message specifying keyboard-interactive method.
1326  */
1327 int
1328 userauth_kbdint(Authctxt *authctxt)
1329 {
1330         static int attempt = 0;
1331
1332         if (attempt++ >= options.number_of_password_prompts)
1333                 return 0;
1334         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1335         if (attempt > 1 && !authctxt->info_req_seen) {
1336                 debug3("userauth_kbdint: disable: no info_req_seen");
1337                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1338                 return 0;
1339         }
1340
1341         debug2("userauth_kbdint");
1342         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1343         packet_put_cstring(authctxt->server_user);
1344         packet_put_cstring(authctxt->service);
1345         packet_put_cstring(authctxt->method->name);
1346         packet_put_cstring("");                                 /* lang */
1347         packet_put_cstring(options.kbd_interactive_devices ?
1348             options.kbd_interactive_devices : "");
1349         packet_send();
1350
1351         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1352         return 1;
1353 }
1354
1355 /*
1356  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1357  */
1358 void
1359 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1360 {
1361         Authctxt *authctxt = ctxt;
1362         char *name, *inst, *lang, *prompt, *response;
1363         u_int num_prompts, i;
1364         int echo = 0;
1365
1366         debug2("input_userauth_info_req");
1367
1368         if (authctxt == NULL)
1369                 fatal("input_userauth_info_req: no authentication context");
1370
1371         authctxt->info_req_seen = 1;
1372
1373         name = packet_get_string(NULL);
1374         inst = packet_get_string(NULL);
1375         lang = packet_get_string(NULL);
1376         if (strlen(name) > 0)
1377                 logit("%s", name);
1378         if (strlen(inst) > 0)
1379                 logit("%s", inst);
1380         xfree(name);
1381         xfree(inst);
1382         xfree(lang);
1383
1384         num_prompts = packet_get_int();
1385         /*
1386          * Begin to build info response packet based on prompts requested.
1387          * We commit to providing the correct number of responses, so if
1388          * further on we run into a problem that prevents this, we have to
1389          * be sure and clean this up and send a correct error response.
1390          */
1391         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1392         packet_put_int(num_prompts);
1393
1394         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1395         for (i = 0; i < num_prompts; i++) {
1396                 prompt = packet_get_string(NULL);
1397                 echo = packet_get_char();
1398
1399                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1400
1401                 packet_put_cstring(response);
1402                 memset(response, 0, strlen(response));
1403                 xfree(response);
1404                 xfree(prompt);
1405         }
1406         packet_check_eom(); /* done with parsing incoming message. */
1407
1408         packet_add_padding(64);
1409         packet_send();
1410 }
1411
1412 static int
1413 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1414     u_char *data, u_int datalen)
1415 {
1416         Buffer b;
1417         struct stat st;
1418         pid_t pid;
1419         int to[2], from[2], status, version = 2;
1420
1421         debug2("ssh_keysign called");
1422
1423         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1424                 error("ssh_keysign: no installed: %s", strerror(errno));
1425                 return -1;
1426         }
1427         if (fflush(stdout) != 0)
1428                 error("ssh_keysign: fflush: %s", strerror(errno));
1429         if (pipe(to) < 0) {
1430                 error("ssh_keysign: pipe: %s", strerror(errno));
1431                 return -1;
1432         }
1433         if (pipe(from) < 0) {
1434                 error("ssh_keysign: pipe: %s", strerror(errno));
1435                 return -1;
1436         }
1437         if ((pid = fork()) < 0) {
1438                 error("ssh_keysign: fork: %s", strerror(errno));
1439                 return -1;
1440         }
1441         if (pid == 0) {
1442                 seteuid(getuid());
1443                 setuid(getuid());
1444                 close(from[0]);
1445                 if (dup2(from[1], STDOUT_FILENO) < 0)
1446                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1447                 close(to[1]);
1448                 if (dup2(to[0], STDIN_FILENO) < 0)
1449                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1450                 close(from[1]);
1451                 close(to[0]);
1452                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1453                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1454                     strerror(errno));
1455         }
1456         close(from[1]);
1457         close(to[0]);
1458
1459         buffer_init(&b);
1460         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1461         buffer_put_string(&b, data, datalen);
1462         if (ssh_msg_send(to[1], version, &b) == -1)
1463                 fatal("ssh_keysign: couldn't send request");
1464
1465         if (ssh_msg_recv(from[0], &b) < 0) {
1466                 error("ssh_keysign: no reply");
1467                 buffer_free(&b);
1468                 return -1;
1469         }
1470         close(from[0]);
1471         close(to[1]);
1472
1473         while (waitpid(pid, &status, 0) < 0)
1474                 if (errno != EINTR)
1475                         break;
1476
1477         if (buffer_get_char(&b) != version) {
1478                 error("ssh_keysign: bad version");
1479                 buffer_free(&b);
1480                 return -1;
1481         }
1482         *sigp = buffer_get_string(&b, lenp);
1483         buffer_free(&b);
1484
1485         return 0;
1486 }
1487
1488 int
1489 userauth_hostbased(Authctxt *authctxt)
1490 {
1491         Key *private = NULL;
1492         Sensitive *sensitive = authctxt->sensitive;
1493         Buffer b;
1494         u_char *signature, *blob;
1495         char *chost, *pkalg, *p;
1496         const char *service;
1497         u_int blen, slen;
1498         int ok, i, len, found = 0;
1499
1500         /* check for a useful key */
1501         for (i = 0; i < sensitive->nkeys; i++) {
1502                 private = sensitive->keys[i];
1503                 if (private && private->type != KEY_RSA1) {
1504                         found = 1;
1505                         /* we take and free the key */
1506                         sensitive->keys[i] = NULL;
1507                         break;
1508                 }
1509         }
1510         if (!found) {
1511                 debug("No more client hostkeys for hostbased authentication.");
1512                 return 0;
1513         }
1514         if (key_to_blob(private, &blob, &blen) == 0) {
1515                 key_free(private);
1516                 return 0;
1517         }
1518         /* figure out a name for the client host */
1519         p = get_local_name(packet_get_connection_in());
1520         if (p == NULL) {
1521                 error("userauth_hostbased: cannot get local ipaddr/name");
1522                 key_free(private);
1523                 return 0;
1524         }
1525         len = strlen(p) + 2;
1526         chost = xmalloc(len);
1527         strlcpy(chost, p, len);
1528         strlcat(chost, ".", len);
1529         debug2("userauth_hostbased: chost %s", chost);
1530         xfree(p);
1531
1532         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1533             authctxt->service;
1534         pkalg = xstrdup(key_ssh_name(private));
1535         buffer_init(&b);
1536         /* construct data */
1537         buffer_put_string(&b, session_id2, session_id2_len);
1538         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1539         buffer_put_cstring(&b, authctxt->server_user);
1540         buffer_put_cstring(&b, service);
1541         buffer_put_cstring(&b, authctxt->method->name);
1542         buffer_put_cstring(&b, pkalg);
1543         buffer_put_string(&b, blob, blen);
1544         buffer_put_cstring(&b, chost);
1545         buffer_put_cstring(&b, authctxt->local_user);
1546 #ifdef DEBUG_PK
1547         buffer_dump(&b);
1548 #endif
1549         if (sensitive->external_keysign)
1550                 ok = ssh_keysign(private, &signature, &slen,
1551                     buffer_ptr(&b), buffer_len(&b));
1552         else
1553                 ok = key_sign(private, &signature, &slen,
1554                     buffer_ptr(&b), buffer_len(&b));
1555         key_free(private);
1556         buffer_free(&b);
1557         if (ok != 0) {
1558                 error("key_sign failed");
1559                 xfree(chost);
1560                 xfree(pkalg);
1561                 return 0;
1562         }
1563         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1564         packet_put_cstring(authctxt->server_user);
1565         packet_put_cstring(authctxt->service);
1566         packet_put_cstring(authctxt->method->name);
1567         packet_put_cstring(pkalg);
1568         packet_put_string(blob, blen);
1569         packet_put_cstring(chost);
1570         packet_put_cstring(authctxt->local_user);
1571         packet_put_string(signature, slen);
1572         memset(signature, 's', slen);
1573         xfree(signature);
1574         xfree(chost);
1575         xfree(pkalg);
1576
1577         packet_send();
1578         return 1;
1579 }
1580
1581 /* find auth method */
1582
1583 /*
1584  * given auth method name, if configurable options permit this method fill
1585  * in auth_ident field and return true, otherwise return false.
1586  */
1587 static int
1588 authmethod_is_enabled(Authmethod *method)
1589 {
1590         if (method == NULL)
1591                 return 0;
1592         /* return false if options indicate this method is disabled */
1593         if  (method->enabled == NULL || *method->enabled == 0)
1594                 return 0;
1595         /* return false if batch mode is enabled but method needs interactive mode */
1596         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1597                 return 0;
1598         return 1;
1599 }
1600
1601 static Authmethod *
1602 authmethod_lookup(const char *name)
1603 {
1604         Authmethod *method = NULL;
1605         if (name != NULL)
1606                 for (method = authmethods; method->name != NULL; method++)
1607                         if (strcmp(name, method->name) == 0)
1608                                 return method;
1609         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1610         return NULL;
1611 }
1612
1613 /* XXX internal state */
1614 static Authmethod *current = NULL;
1615 static char *supported = NULL;
1616 static char *preferred = NULL;
1617
1618 /*
1619  * Given the authentication method list sent by the server, return the
1620  * next method we should try.  If the server initially sends a nil list,
1621  * use a built-in default list.
1622  */
1623 static Authmethod *
1624 authmethod_get(char *authlist)
1625 {
1626         char *name = NULL;
1627         u_int next;
1628
1629         /* Use a suitable default if we're passed a nil list.  */
1630         if (authlist == NULL || strlen(authlist) == 0)
1631                 authlist = options.preferred_authentications;
1632
1633         if (supported == NULL || strcmp(authlist, supported) != 0) {
1634                 debug3("start over, passed a different list %s", authlist);
1635                 if (supported != NULL)
1636                         xfree(supported);
1637                 supported = xstrdup(authlist);
1638                 preferred = options.preferred_authentications;
1639                 debug3("preferred %s", preferred);
1640                 current = NULL;
1641         } else if (current != NULL && authmethod_is_enabled(current))
1642                 return current;
1643
1644         for (;;) {
1645                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1646                         debug("No more authentication methods to try.");
1647                         current = NULL;
1648                         return NULL;
1649                 }
1650                 preferred += next;
1651                 debug3("authmethod_lookup %s", name);
1652                 debug3("remaining preferred: %s", preferred);
1653                 if ((current = authmethod_lookup(name)) != NULL &&
1654                     authmethod_is_enabled(current)) {
1655                         debug3("authmethod_is_enabled %s", name);
1656                         debug("Next authentication method: %s", name);
1657                         return current;
1658                 }
1659         }
1660 }
1661
1662 static char *
1663 authmethods_get(void)
1664 {
1665         Authmethod *method = NULL;
1666         Buffer b;
1667         char *list;
1668
1669         buffer_init(&b);
1670         for (method = authmethods; method->name != NULL; method++) {
1671                 if (authmethod_is_enabled(method)) {
1672                         if (buffer_len(&b) > 0)
1673                                 buffer_append(&b, ",", 1);
1674                         buffer_append(&b, method->name, strlen(method->name));
1675                 }
1676         }
1677         buffer_append(&b, "\0", 1);
1678         list = xstrdup(buffer_ptr(&b));
1679         buffer_free(&b);
1680         return list;
1681 }