openssh/sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.166 2008/07/17 08:48:00 djm Exp $ */
   2 /*
   3  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "includes.h"
  27
  28 #include <sys/types.h>
  29 #include <sys/socket.h>
  30 #include <sys/wait.h>
  31 #include <sys/stat.h>
  32
  33 #include <errno.h>
  34 #include <netdb.h>
  35 #include <pwd.h>
  36 #include <signal.h>
  37 #include <stdarg.h>
  38 #include <stdio.h>
  39 #include <string.h>
  40 #include <unistd.h>
  41 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H)
  42 #include <vis.h>
  43 #endif
  44
  45 #include "openbsd-compat/sys-queue.h"
  46
  47 #include "xmalloc.h"
  48 #include "ssh.h"
  49 #include "ssh2.h"
  50 #include "buffer.h"
  51 #include "packet.h"
  52 #include "compat.h"
  53 #include "cipher.h"
  54 #include "key.h"
  55 #include "kex.h"
  56 #include "myproposal.h"
  57 #include "sshconnect.h"
  58 #include "authfile.h"
  59 #include "dh.h"
  60 #include "authfd.h"
  61 #include "log.h"
  62 #include "readconf.h"
  63 #include "misc.h"
  64 #include "match.h"
  65 #include "dispatch.h"
  66 #include "canohost.h"
  67 #include "msg.h"
  68 #include "pathnames.h"
  69 #include "uidswap.h"
  70
  71 #ifdef GSSAPI
  72 #include "ssh-gss.h"
  73 #endif
  74
  75 /* import */
  76 extern char *client_version_string;
  77 extern char *server_version_string;
  78 extern Options options;
  79
  80 /* tty_flag is set in ssh.c. use this in ssh_userauth2 */
  81 /* if it is set then prevent the switch to the null cipher */
  82
  83 extern int tty_flag;
  84
  85 /* tty_flag is set in ssh.c. use this in ssh_userauth2 */
  86 /* if it is set then prevent the switch to the null cipher */
  87
  88 extern int tty_flag;
  89
  90 /*
  91  * SSH2 key exchange
  92  */
  93
  94 u_char *session_id2 = NULL;
  95 u_int session_id2_len = 0;
  96
  97 char *xxx_host;
  98 struct sockaddr *xxx_hostaddr;
  99
 100 Kex *xxx_kex = NULL;
 101
 102 static int
 103 verify_host_key_callback(Key *hostkey)
 104 {
 105         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
 106                 fatal("Host key verification failed.");
 107         return 0;
 108 }
 109
 110 void
 111 ssh_kex2(char *host, struct sockaddr *hostaddr)
 112 {
 113         Kex *kex;
 114
 115 #ifdef GSSAPI
 116         char *orig = NULL, *gss = NULL;
 117         char *gss_host = NULL;
 118 #endif
 119
 120         xxx_host = host;
 121         xxx_hostaddr = hostaddr;
 122
 123 #ifdef GSSAPI
 124         if (options.gss_keyex) {
 125                 /* Add the GSSAPI mechanisms currently supported on this
 126                  * client to the key exchange algorithm proposal */
 127                 orig = myproposal[PROPOSAL_KEX_ALGS];
 128
 129                 if (options.gss_trust_dns)
 130                         gss_host = (char *)get_canonical_hostname(1);
 131                 else
 132                         gss_host = host;
 133
 134                 gss = ssh_gssapi_client_mechanisms(gss_host);
 135                 if (gss) {
 136                         debug("Offering GSSAPI proposal: %s", gss);
 137                         xasprintf(&myproposal[PROPOSAL_KEX_ALGS],
 138                             "%s,%s", gss, orig);
 139                 }
 140         }
 141 #endif
 142
 143         if (options.ciphers == (char *)-1) {
 144                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 145                 options.ciphers = NULL;
 146         }
 147         if (options.ciphers != NULL) {
 148                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 149                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 150         }
 151         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 152             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 153         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 154             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 155         if (options.compression) {
 156                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 157                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 158         } else {
 159                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 160                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 161         }
 162         if (options.macs != NULL) {
 163                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 164                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 165         }
 166         if (options.hostkeyalgorithms != NULL)
 167                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 168                     options.hostkeyalgorithms;
 169
 170 #ifdef GSSAPI
 171         /* If we've got GSSAPI algorithms, then we also support the
 172          * 'null' hostkey, as a last resort */
 173         if (options.gss_keyex && gss) {
 174                 orig = myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
 175                 xasprintf(&myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS],
 176                     "%s,null", orig);
 177         }
 178 #endif
 179
 180         if (options.rekey_limit)
 181                 packet_set_rekey_limit((u_int32_t)options.rekey_limit);
 182
 183         /* start key exchange */
 184         kex = kex_setup(myproposal);
 185         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 186         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 187         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 188         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 189 #ifdef GSSAPI
 190         kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client;
 191         kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_client;
 192         kex->kex[KEX_GSS_GEX_SHA1] = kexgss_client;
 193 #endif
 194         kex->client_version_string=client_version_string;
 195         kex->server_version_string=server_version_string;
 196         kex->verify_host_key=&verify_host_key_callback;
 197
 198 #ifdef GSSAPI
 199         kex->gss_deleg_creds = options.gss_deleg_creds;
 200         kex->gss_trust_dns = options.gss_trust_dns;
 201         kex->gss_host = gss_host;
 202 #endif
 203
 204         xxx_kex = kex;
 205
 206         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 207
 208         session_id2 = kex->session_id;
 209         session_id2_len = kex->session_id_len;
 210
 211 #ifdef DEBUG_KEXDH
 212         /* send 1st encrypted/maced/compressed message */
 213         packet_start(SSH2_MSG_IGNORE);
 214         packet_put_cstring("markus");
 215         packet_send();
 216         packet_write_wait();
 217 #endif
 218 }
 219
 220 /*
 221  * Authenticate user
 222  */
 223
 224 typedef struct Authctxt Authctxt;
 225 typedef struct Authmethod Authmethod;
 226 typedef struct identity Identity;
 227 typedef struct idlist Idlist;
 228
 229 struct identity {
 230         TAILQ_ENTRY(identity) next;
 231         AuthenticationConnection *ac;   /* set if agent supports key */
 232         Key     *key;                   /* public/private key */
 233         char    *filename;              /* comment for agent-only keys */
 234         int     tried;
 235         int     isprivate;              /* key points to the private key */
 236 };
 237 TAILQ_HEAD(idlist, identity);
 238
 239 struct Authctxt {
 240         const char *server_user;
 241         const char *local_user;
 242         const char *host;
 243         const char *service;
 244         Authmethod *method;
 245         int success;
 246         char *authlist;
 247         /* pubkey */
 248         Idlist keys;
 249         AuthenticationConnection *agent;
 250         /* hostbased */
 251         Sensitive *sensitive;
 252         /* kbd-interactive */
 253         int info_req_seen;
 254         /* generic */
 255         void *methoddata;
 256 };
 257 struct Authmethod {
 258         char    *name;          /* string to compare against server's list */
 259         int     (*userauth)(Authctxt *authctxt);
 260         int     *enabled;       /* flag in option struct that enables method */
 261         int     *batch_flag;    /* flag in option struct that disables method */
 262 };
 263
 264 void    input_userauth_success(int, u_int32_t, void *);
 265 void    input_userauth_failure(int, u_int32_t, void *);
 266 void    input_userauth_banner(int, u_int32_t, void *);
 267 void    input_userauth_error(int, u_int32_t, void *);
 268 void    input_userauth_info_req(int, u_int32_t, void *);
 269 void    input_userauth_pk_ok(int, u_int32_t, void *);
 270 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 271
 272 int     userauth_none(Authctxt *);
 273 int     userauth_pubkey(Authctxt *);
 274 int     userauth_passwd(Authctxt *);
 275 int     userauth_kbdint(Authctxt *);
 276 int     userauth_hostbased(Authctxt *);
 277 int     userauth_kerberos(Authctxt *);
 278
 279 #ifdef GSSAPI
 280 int     userauth_external(Authctxt *authctxt);
 281 int     userauth_gssapi(Authctxt *authctxt);
 282 int     userauth_gssapi_with_mic(Authctxt *authctxt);
 283 int     userauth_gssapi_without_mic(Authctxt *authctxt);
 284 void    input_gssapi_response(int type, u_int32_t, void *);
 285 void    input_gssapi_token(int type, u_int32_t, void *);
 286 void    input_gssapi_hash(int type, u_int32_t, void *);
 287 void    input_gssapi_error(int, u_int32_t, void *);
 288 void    input_gssapi_errtok(int, u_int32_t, void *);
 289 int     userauth_gsskeyex(Authctxt *authctxt);
 290 #endif
 291
 292 void    userauth(Authctxt *, char *);
 293
 294 static int sign_and_send_pubkey(Authctxt *, Identity *);
 295 static void pubkey_prepare(Authctxt *);
 296 static void pubkey_cleanup(Authctxt *);
 297 static Key *load_identity_file(char *);
 298
 299 static Authmethod *authmethod_get(char *authlist);
 300 static Authmethod *authmethod_lookup(const char *name);
 301 static char *authmethods_get(void);
 302
 303 Authmethod authmethods[] = {
 304 #ifdef GSSAPI
 305         {"gssapi-keyex",
 306                 userauth_gsskeyex,
 307                 &options.gss_authentication,
 308                 NULL},
 309         {"external-keyx",
 310                 userauth_external,
 311                 &options.gss_authentication,
 312                 NULL},
 313         {"gssapi-with-mic",
 314                 userauth_gssapi,
 315                 &options.gss_authentication,
 316                 NULL},
 317         {"gssapi",
 318                 userauth_gssapi,
 319                 &options.gss_authentication,
 320                 NULL},
 321 #endif
 322         {"hostbased",
 323                 userauth_hostbased,
 324                 &options.hostbased_authentication,
 325                 NULL},
 326         {"publickey",
 327                 userauth_pubkey,
 328                 &options.pubkey_authentication,
 329                 NULL},
 330         {"keyboard-interactive",
 331                 userauth_kbdint,
 332                 &options.kbd_interactive_authentication,
 333                 &options.batch_mode},
 334         {"password",
 335                 userauth_passwd,
 336                 &options.password_authentication,
 337                 &options.batch_mode},
 338         {"none",
 339                 userauth_none,
 340                 NULL,
 341                 NULL},
 342         {NULL, NULL, NULL, NULL}
 343 };
 344
 345 void
 346 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 347     Sensitive *sensitive)
 348 {
 349         Authctxt authctxt;
 350         int type;
 351
 352         if (options.challenge_response_authentication)
 353                 options.kbd_interactive_authentication = 1;
 354
 355         packet_start(SSH2_MSG_SERVICE_REQUEST);
 356         packet_put_cstring("ssh-userauth");
 357         packet_send();
 358         debug("SSH2_MSG_SERVICE_REQUEST sent");
 359         packet_write_wait();
 360         type = packet_read();
 361         if (type != SSH2_MSG_SERVICE_ACCEPT)
 362                 fatal("Server denied authentication request: %d", type);
 363         if (packet_remaining() > 0) {
 364                 char *reply = packet_get_string(NULL);
 365                 debug2("service_accept: %s", reply);
 366                 xfree(reply);
 367         } else {
 368                 debug2("buggy server: service_accept w/o service");
 369         }
 370         packet_check_eom();
 371         debug("SSH2_MSG_SERVICE_ACCEPT received");
 372
 373         if (options.preferred_authentications == NULL)
 374                 options.preferred_authentications = authmethods_get();
 375
 376         /* setup authentication context */
 377         memset(&authctxt, 0, sizeof(authctxt));
 378         pubkey_prepare(&authctxt);
 379         authctxt.server_user = server_user;
 380         authctxt.local_user = local_user;
 381         authctxt.host = host;
 382         authctxt.service = "ssh-connection";            /* service name */
 383         authctxt.success = 0;
 384         authctxt.method = authmethod_lookup("none");
 385         authctxt.authlist = NULL;
 386         authctxt.methoddata = NULL;
 387         authctxt.sensitive = sensitive;
 388         authctxt.info_req_seen = 0;
 389         if (authctxt.method == NULL)
 390                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 391
 392         /* initial userauth request */
 393         userauth_none(&authctxt);
 394
 395         dispatch_init(&input_userauth_error);
 396         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 397         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 398         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 399         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 400
 401         pubkey_cleanup(&authctxt);
 402         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 403
 404         /* if the user wants to use the none cipher do it */
 405         /* post authentication and only if the right conditions are met */
 406         /* both of the NONE commands must be true and there must be no */
 407         /* tty allocated */
 408         if ((options.none_switch == 1) && (options.none_enabled == 1))
 409         {
 410                 if (!tty_flag) /* no null on tty sessions */
 411                 {
 412                         debug("Requesting none rekeying...");
 413                         myproposal[PROPOSAL_ENC_ALGS_STOC] = "none";
 414                         myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none";
 415                         kex_prop2buf(&xxx_kex->my,myproposal);
 416                         packet_request_rekeying();
 417                         fprintf(stderr, "WARNING: ENABLED NONE CIPHER\n");
 418                 }
 419                 else
 420                 {
 421                         /* requested NONE cipher when in a tty */
 422                         debug("Cannot switch to NONE cipher with tty allocated");
 423                         fprintf(stderr, "NONE cipher switch disabled when a TTY is allocated\n");
 424                 }
 425         }
 426         debug("Authentication succeeded (%s).", authctxt.method->name);
 427 }
 428
 429 void
 430 userauth(Authctxt *authctxt, char *authlist)
 431 {
 432         if (authctxt->methoddata) {
 433                 xfree(authctxt->methoddata);
 434                 authctxt->methoddata = NULL;
 435         }
 436         if (authlist == NULL) {
 437                 authlist = authctxt->authlist;
 438         } else {
 439                 if (authctxt->authlist)
 440                         xfree(authctxt->authlist);
 441                 authctxt->authlist = authlist;
 442         }
 443         for (;;) {
 444                 Authmethod *method = authmethod_get(authlist);
 445                 if (method == NULL)
 446                         fatal("Permission denied (%s).", authlist);
 447                 authctxt->method = method;
 448
 449                 /* reset the per method handler */
 450                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 451                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 452
 453                 /* and try new method */
 454                 if (method->userauth(authctxt) != 0) {
 455                         debug2("we sent a %s packet, wait for reply", method->name);
 456                         break;
 457                 } else {
 458                         debug2("we did not send a packet, disable method");
 459                         method->enabled = NULL;
 460                 }
 461         }
 462 }
 463
 464 void
 465 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 466 {
 467         fatal("input_userauth_error: bad message during authentication: "
 468             "type %d", type);
 469 }
 470
 471 void
 472 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 473 {
 474         char *msg, *raw, *lang;
 475         u_int len;
 476
 477         debug3("input_userauth_banner");
 478         raw = packet_get_string(&len);
 479         lang = packet_get_string(NULL);
 480         if (options.log_level >= SYSLOG_LEVEL_INFO) {
 481                 if (len > 65536)
 482                         len = 65536;
 483                 msg = xmalloc(len * 4); /* max expansion from strnvis() */
 484                 strnvis(msg, raw, len * 4, VIS_SAFE|VIS_OCTAL);
 485                 fprintf(stderr, "%s", msg);
 486                 xfree(msg);
 487         }
 488         xfree(raw);
 489         xfree(lang);
 490 }
 491
 492 void
 493 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 494 {
 495         Authctxt *authctxt = ctxt;
 496         if (authctxt == NULL)
 497                 fatal("input_userauth_success: no authentication context");
 498         if (authctxt->authlist) {
 499                 xfree(authctxt->authlist);
 500                 authctxt->authlist = NULL;
 501         }
 502         if (authctxt->methoddata) {
 503                 xfree(authctxt->methoddata);
 504                 authctxt->methoddata = NULL;
 505         }
 506         authctxt->success = 1;                  /* break out */
 507 }
 508
 509 void
 510 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 511 {
 512         Authctxt *authctxt = ctxt;
 513         char *authlist = NULL;
 514         int partial;
 515
 516         if (authctxt == NULL)
 517                 fatal("input_userauth_failure: no authentication context");
 518
 519         authlist = packet_get_string(NULL);
 520         partial = packet_get_char();
 521         packet_check_eom();
 522
 523         if (partial != 0)
 524                 logit("Authenticated with partial success.");
 525         debug("Authentications that can continue: %s", authlist);
 526
 527         userauth(authctxt, authlist);
 528 }
 529 void
 530 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 531 {
 532         Authctxt *authctxt = ctxt;
 533         Key *key = NULL;
 534         Identity *id = NULL;
 535         Buffer b;
 536         int pktype, sent = 0;
 537         u_int alen, blen;
 538         char *pkalg, *fp;
 539         u_char *pkblob;
 540
 541         if (authctxt == NULL)
 542                 fatal("input_userauth_pk_ok: no authentication context");
 543         if (datafellows & SSH_BUG_PKOK) {
 544                 /* this is similar to SSH_BUG_PKAUTH */
 545                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 546                 pkblob = packet_get_string(&blen);
 547                 buffer_init(&b);
 548                 buffer_append(&b, pkblob, blen);
 549                 pkalg = buffer_get_string(&b, &alen);
 550                 buffer_free(&b);
 551         } else {
 552                 pkalg = packet_get_string(&alen);
 553                 pkblob = packet_get_string(&blen);
 554         }
 555         packet_check_eom();
 556
 557         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 558
 559         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 560                 debug("unknown pkalg %s", pkalg);
 561                 goto done;
 562         }
 563         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 564                 debug("no key from blob. pkalg %s", pkalg);
 565                 goto done;
 566         }
 567         if (key->type != pktype) {
 568                 error("input_userauth_pk_ok: type mismatch "
 569                     "for decoded key (received %d, expected %d)",
 570                     key->type, pktype);
 571                 goto done;
 572         }
 573         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 574         debug2("input_userauth_pk_ok: fp %s", fp);
 575         xfree(fp);
 576
 577         /*
 578          * search keys in the reverse order, because last candidate has been
 579          * moved to the end of the queue.  this also avoids confusion by
 580          * duplicate keys
 581          */
 582         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 583                 if (key_equal(key, id->key)) {
 584                         sent = sign_and_send_pubkey(authctxt, id);
 585                         break;
 586                 }
 587         }
 588 done:
 589         if (key != NULL)
 590                 key_free(key);
 591         xfree(pkalg);
 592         xfree(pkblob);
 593
 594         /* try another method if we did not send a packet */
 595         if (sent == 0)
 596                 userauth(authctxt, NULL);
 597 }
 598
 599 #ifdef GSSAPI
 600 int
 601 userauth_gssapi(Authctxt *authctxt)
 602 {
 603         Gssctxt *gssctxt = NULL;
 604         static gss_OID_set gss_supported = NULL;
 605         static u_int mech = 0;
 606         OM_uint32 min;
 607         int ok = 0;
 608         char *gss_host = NULL;
 609
 610         if (!options.gss_authentication) {
 611                 verbose("GSSAPI authentication disabled.");
 612                 return 0;
 613         }
 614
 615         if (options.gss_trust_dns)
 616                 gss_host = (char *)get_canonical_hostname(1);
 617         else
 618                 gss_host = (char *)authctxt->host;
 619
 620         /* Try one GSSAPI method at a time, rather than sending them all at
 621          * once. */
 622
 623         if (gss_supported == NULL)
 624                 gss_indicate_mechs(&min, &gss_supported);
 625
 626         /* Check to see if the mechanism is usable before we offer it */
 627         while (mech < gss_supported->count && !ok) {
 628                 /* My DER encoding requires length<128 */
 629                 if (gss_supported->elements[mech].length < 128 &&
 630                     ssh_gssapi_check_mechanism(&gssctxt,
 631                     &gss_supported->elements[mech], gss_host)) {
 632                         ok = 1; /* Mechanism works */
 633                 } else {
 634                         mech++;
 635                 }
 636         }
 637
 638         if (!ok)
 639                 return 0;
 640
 641         authctxt->methoddata=(void *)gssctxt;
 642
 643         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 644         packet_put_cstring(authctxt->server_user);
 645         packet_put_cstring(authctxt->service);
 646         packet_put_cstring(authctxt->method->name);
 647
 648         packet_put_int(1);
 649
 650         packet_put_int((gss_supported->elements[mech].length) + 2);
 651         packet_put_char(SSH_GSS_OIDTYPE);
 652         packet_put_char(gss_supported->elements[mech].length);
 653         packet_put_raw(gss_supported->elements[mech].elements,
 654             gss_supported->elements[mech].length);
 655
 656         packet_send();
 657
 658         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 659         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 660         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 661         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 662
 663         mech++; /* Move along to next candidate */
 664
 665         return 1;
 666 }
 667
 668 static OM_uint32
 669 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 670 {
 671         Authctxt *authctxt = ctxt;
 672         Gssctxt *gssctxt = authctxt->methoddata;
 673         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 674         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 675         gss_buffer_desc gssbuf;
 676         OM_uint32 status, ms, flags;
 677         Buffer b;
 678
 679         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 680             recv_tok, &send_tok, &flags);
 681
 682         if (send_tok.length > 0) {
 683                 if (GSS_ERROR(status))
 684                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 685                 else
 686                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 687
 688                 packet_put_string(send_tok.value, send_tok.length);
 689                 packet_send();
 690                 gss_release_buffer(&ms, &send_tok);
 691         }
 692
 693         if (status == GSS_S_COMPLETE) {
 694                 /* send either complete or MIC, depending on mechanism */
 695                 if (strcmp(authctxt->method->name,"gssapi")==0 ||
 696                     (!(flags & GSS_C_INTEG_FLAG))) {
 697                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 698                         packet_send();
 699                 } else {
 700                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 701                             authctxt->service, "gssapi-with-mic");
 702
 703                         gssbuf.value = buffer_ptr(&b);
 704                         gssbuf.length = buffer_len(&b);
 705
 706                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 707
 708                         if (!GSS_ERROR(status)) {
 709                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 710                                 packet_put_string(mic.value, mic.length);
 711
 712                                 packet_send();
 713                         }
 714
 715                         buffer_free(&b);
 716                         gss_release_buffer(&ms, &mic);
 717                 }
 718         }
 719
 720         return status;
 721 }
 722
 723 void
 724 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 725 {
 726         Authctxt *authctxt = ctxt;
 727         Gssctxt *gssctxt;
 728         u_int oidlen;
 729         u_char *oidv;
 730
 731         if (authctxt == NULL)
 732                 fatal("input_gssapi_response: no authentication context");
 733         gssctxt = authctxt->methoddata;
 734
 735         /* Setup our OID */
 736         oidv = packet_get_string(&oidlen);
 737
 738         if (oidlen <= 2 ||
 739             oidv[0] != SSH_GSS_OIDTYPE ||
 740             oidv[1] != oidlen - 2) {
 741                 xfree(oidv);
 742                 debug("Badly encoded mechanism OID received");
 743                 userauth(authctxt, NULL);
 744                 return;
 745         }
 746
 747         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 748                 fatal("Server returned different OID than expected");
 749
 750         packet_check_eom();
 751
 752         xfree(oidv);
 753
 754         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 755                 /* Start again with next method on list */
 756                 debug("Trying to start again");
 757                 userauth(authctxt, NULL);
 758                 return;
 759         }
 760 }
 761
 762 void
 763 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 764 {
 765         Authctxt *authctxt = ctxt;
 766         gss_buffer_desc recv_tok;
 767         OM_uint32 status;
 768         u_int slen;
 769
 770         if (authctxt == NULL)
 771                 fatal("input_gssapi_response: no authentication context");
 772
 773         recv_tok.value = packet_get_string(&slen);
 774         recv_tok.length = slen; /* safe typecast */
 775
 776         packet_check_eom();
 777
 778         status = process_gssapi_token(ctxt, &recv_tok);
 779
 780         xfree(recv_tok.value);
 781
 782         if (GSS_ERROR(status)) {
 783                 /* Start again with the next method in the list */
 784                 userauth(authctxt, NULL);
 785                 return;
 786         }
 787 }
 788
 789 void
 790 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 791 {
 792         Authctxt *authctxt = ctxt;
 793         Gssctxt *gssctxt;
 794         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 795         gss_buffer_desc recv_tok;
 796         OM_uint32 status, ms;
 797         u_int len;
 798
 799         if (authctxt == NULL)
 800                 fatal("input_gssapi_response: no authentication context");
 801         gssctxt = authctxt->methoddata;
 802
 803         recv_tok.value = packet_get_string(&len);
 804         recv_tok.length = len;
 805
 806         packet_check_eom();
 807
 808         /* Stick it into GSSAPI and see what it says */
 809         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 810             &recv_tok, &send_tok, NULL);
 811
 812         xfree(recv_tok.value);
 813         gss_release_buffer(&ms, &send_tok);
 814
 815         /* Server will be returning a failed packet after this one */
 816 }
 817
 818 void
 819 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 820 {
 821         OM_uint32 maj, min;
 822         char *msg;
 823         char *lang;
 824
 825         maj=packet_get_int();
 826         min=packet_get_int();
 827         msg=packet_get_string(NULL);
 828         lang=packet_get_string(NULL);
 829
 830         packet_check_eom();
 831
 832         debug("Server GSSAPI Error:\n%s", msg);
 833         xfree(msg);
 834         xfree(lang);
 835 }
 836
 837 #ifdef GSI
 838 extern
 839 const gss_OID_desc * const              gss_mech_globus_gssapi_openssl;
 840 #define is_gsi_oid(oid) \
 841   (oid->length == gss_mech_globus_gssapi_openssl->length && \
 842    (memcmp(oid->elements, gss_mech_globus_gssapi_openssl->elements, \
 843            oid->length) == 0))
 844 #endif
 845
 846 int
 847 userauth_external(Authctxt *authctxt)
 848 {
 849         static int attempt = 0;
 850
 851         if (attempt++ >= 1)
 852                 return 0;
 853
 854         /* The client MUST NOT try this method if initial key exchange
 855            was not performed using a GSSAPI-based key exchange
 856            method. */
 857         if (gss_kex_context == NULL) {
 858                 debug2("gsskex not performed, skipping external-keyx");
 859                 return 0;
 860         }
 861
 862         debug2("userauth_external");
 863         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 864 #ifdef GSI
 865         if (options.implicit && is_gsi_oid(gss_kex_context->oid)) {
 866         packet_put_cstring("");
 867         } else {
 868 #endif
 869         packet_put_cstring(authctxt->server_user);
 870 #ifdef GSI
 871         }
 872 #endif
 873         packet_put_cstring(authctxt->service);
 874         packet_put_cstring(authctxt->method->name);
 875         packet_send();
 876         packet_write_wait();
 877         return 1;
 878 }
 879 int
 880 userauth_gsskeyex(Authctxt *authctxt)
 881 {
 882         Buffer b;
 883         gss_buffer_desc gssbuf;
 884         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 885         OM_uint32 ms;
 886
 887         static int attempt = 0;
 888         if (attempt++ >= 1)
 889                 return (0);
 890
 891         if (gss_kex_context == NULL) {
 892                 debug("No valid Key exchange context");
 893                 return (0);
 894         }
 895
 896 #ifdef GSI
 897         if (options.implicit && is_gsi_oid(gss_kex_context->oid)) {
 898         ssh_gssapi_buildmic(&b, "", authctxt->service, "gssapi-keyex");
 899         } else {
 900 #endif
 901         ssh_gssapi_buildmic(&b, authctxt->server_user, authctxt->service,
 902             "gssapi-keyex");
 903 #ifdef GSI
 904         }
 905 #endif
 906
 907         gssbuf.value = buffer_ptr(&b);
 908         gssbuf.length = buffer_len(&b);
 909
 910         if (GSS_ERROR(ssh_gssapi_sign(gss_kex_context, &gssbuf, &mic))) {
 911                 buffer_free(&b);
 912                 return (0);
 913         }
 914
 915         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 916 #ifdef GSI
 917         if (options.implicit && is_gsi_oid(gss_kex_context->oid)) {
 918         packet_put_cstring("");
 919         } else {
 920 #endif
 921         packet_put_cstring(authctxt->server_user);
 922 #ifdef GSI
 923         }
 924 #endif
 925         packet_put_cstring(authctxt->service);
 926         packet_put_cstring(authctxt->method->name);
 927         packet_put_string(mic.value, mic.length);
 928         packet_send();
 929
 930         buffer_free(&b);
 931         gss_release_buffer(&ms, &mic);
 932
 933         return (1);
 934 }
 935
 936 #endif /* GSSAPI */
 937
 938 int
 939 userauth_none(Authctxt *authctxt)
 940 {
 941         /* initial userauth request */
 942         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 943         packet_put_cstring(authctxt->server_user);
 944         packet_put_cstring(authctxt->service);
 945         packet_put_cstring(authctxt->method->name);
 946         packet_send();
 947         return 1;
 948 }
 949
 950 int
 951 userauth_passwd(Authctxt *authctxt)
 952 {
 953         static int attempt = 0;
 954         char prompt[150];
 955         char *password;
 956
 957         if (attempt++ >= options.number_of_password_prompts)
 958                 return 0;
 959
 960         if (attempt != 1)
 961                 error("Permission denied, please try again.");
 962
 963         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 964             authctxt->server_user, authctxt->host);
 965         password = read_passphrase(prompt, 0);
 966         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 967         packet_put_cstring(authctxt->server_user);
 968         packet_put_cstring(authctxt->service);
 969         packet_put_cstring(authctxt->method->name);
 970         packet_put_char(0);
 971         packet_put_cstring(password);
 972         memset(password, 0, strlen(password));
 973         xfree(password);
 974         packet_add_padding(64);
 975         packet_send();
 976
 977         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 978             &input_userauth_passwd_changereq);
 979
 980         return 1;
 981 }
 982 /*
 983  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 984  */
 985 void
 986 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 987 {
 988         Authctxt *authctxt = ctxt;
 989         char *info, *lang, *password = NULL, *retype = NULL;
 990         char prompt[150];
 991
 992         debug2("input_userauth_passwd_changereq");
 993
 994         if (authctxt == NULL)
 995                 fatal("input_userauth_passwd_changereq: "
 996                     "no authentication context");
 997
 998         info = packet_get_string(NULL);
 999         lang = packet_get_string(NULL);
1000         if (strlen(info) > 0)
1001                 logit("%s", info);
1002         xfree(info);
1003         xfree(lang);
1004         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1005         packet_put_cstring(authctxt->server_user);
1006         packet_put_cstring(authctxt->service);
1007         packet_put_cstring(authctxt->method->name);
1008         packet_put_char(1);                     /* additional info */
1009         snprintf(prompt, sizeof(prompt),
1010             "Enter %.30s@%.128s's old password: ",
1011             authctxt->server_user, authctxt->host);
1012         password = read_passphrase(prompt, 0);
1013         packet_put_cstring(password);
1014         memset(password, 0, strlen(password));
1015         xfree(password);
1016         password = NULL;
1017         while (password == NULL) {
1018                 snprintf(prompt, sizeof(prompt),
1019                     "Enter %.30s@%.128s's new password: ",
1020                     authctxt->server_user, authctxt->host);
1021                 password = read_passphrase(prompt, RP_ALLOW_EOF);
1022                 if (password == NULL) {
1023                         /* bail out */
1024                         return;
1025                 }
1026                 snprintf(prompt, sizeof(prompt),
1027                     "Retype %.30s@%.128s's new password: ",
1028                     authctxt->server_user, authctxt->host);
1029                 retype = read_passphrase(prompt, 0);
1030                 if (strcmp(password, retype) != 0) {
1031                         memset(password, 0, strlen(password));
1032                         xfree(password);
1033                         logit("Mismatch; try again, EOF to quit.");
1034                         password = NULL;
1035                 }
1036                 memset(retype, 0, strlen(retype));
1037                 xfree(retype);
1038         }
1039         packet_put_cstring(password);
1040         memset(password, 0, strlen(password));
1041         xfree(password);
1042         packet_add_padding(64);
1043         packet_send();
1044
1045         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
1046             &input_userauth_passwd_changereq);
1047 }
1048
1049 static int
1050 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
1051     u_char *data, u_int datalen)
1052 {
1053         Key *prv;
1054         int ret;
1055
1056         /* the agent supports this key */
1057         if (id->ac)
1058                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1059                     data, datalen));
1060         /*
1061          * we have already loaded the private key or
1062          * the private key is stored in external hardware
1063          */
1064         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1065                 return (key_sign(id->key, sigp, lenp, data, datalen));
1066         /* load the private key from the file */
1067         if ((prv = load_identity_file(id->filename)) == NULL)
1068                 return (-1);
1069         ret = key_sign(prv, sigp, lenp, data, datalen);
1070         key_free(prv);
1071         return (ret);
1072 }
1073
1074 static int
1075 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1076 {
1077         Buffer b;
1078         u_char *blob, *signature;
1079         u_int bloblen, slen;
1080         u_int skip = 0;
1081         int ret = -1;
1082         int have_sig = 1;
1083
1084         debug3("sign_and_send_pubkey");
1085
1086         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1087                 /* we cannot handle this key */
1088                 debug3("sign_and_send_pubkey: cannot handle key");
1089                 return 0;
1090         }
1091         /* data to be signed */
1092         buffer_init(&b);
1093         if (datafellows & SSH_OLD_SESSIONID) {
1094                 buffer_append(&b, session_id2, session_id2_len);
1095                 skip = session_id2_len;
1096         } else {
1097                 buffer_put_string(&b, session_id2, session_id2_len);
1098                 skip = buffer_len(&b);
1099         }
1100         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1101         buffer_put_cstring(&b, authctxt->server_user);
1102         buffer_put_cstring(&b,
1103             datafellows & SSH_BUG_PKSERVICE ?
1104             "ssh-userauth" :
1105             authctxt->service);
1106         if (datafellows & SSH_BUG_PKAUTH) {
1107                 buffer_put_char(&b, have_sig);
1108         } else {
1109                 buffer_put_cstring(&b, authctxt->method->name);
1110                 buffer_put_char(&b, have_sig);
1111                 buffer_put_cstring(&b, key_ssh_name(id->key));
1112         }
1113         buffer_put_string(&b, blob, bloblen);
1114
1115         /* generate signature */
1116         ret = identity_sign(id, &signature, &slen,
1117             buffer_ptr(&b), buffer_len(&b));
1118         if (ret == -1) {
1119                 xfree(blob);
1120                 buffer_free(&b);
1121                 return 0;
1122         }
1123 #ifdef DEBUG_PK
1124         buffer_dump(&b);
1125 #endif
1126         if (datafellows & SSH_BUG_PKSERVICE) {
1127                 buffer_clear(&b);
1128                 buffer_append(&b, session_id2, session_id2_len);
1129                 skip = session_id2_len;
1130                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1131                 buffer_put_cstring(&b, authctxt->server_user);
1132                 buffer_put_cstring(&b, authctxt->service);
1133                 buffer_put_cstring(&b, authctxt->method->name);
1134                 buffer_put_char(&b, have_sig);
1135                 if (!(datafellows & SSH_BUG_PKAUTH))
1136                         buffer_put_cstring(&b, key_ssh_name(id->key));
1137                 buffer_put_string(&b, blob, bloblen);
1138         }
1139         xfree(blob);
1140
1141         /* append signature */
1142         buffer_put_string(&b, signature, slen);
1143         xfree(signature);
1144
1145         /* skip session id and packet type */
1146         if (buffer_len(&b) < skip + 1)
1147                 fatal("userauth_pubkey: internal error");
1148         buffer_consume(&b, skip + 1);
1149
1150         /* put remaining data from buffer into packet */
1151         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1152         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1153         buffer_free(&b);
1154         packet_send();
1155
1156         return 1;
1157 }
1158
1159 static int
1160 send_pubkey_test(Authctxt *authctxt, Identity *id)
1161 {
1162         u_char *blob;
1163         u_int bloblen, have_sig = 0;
1164
1165         debug3("send_pubkey_test");
1166
1167         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1168                 /* we cannot handle this key */
1169                 debug3("send_pubkey_test: cannot handle key");
1170                 return 0;
1171         }
1172         /* register callback for USERAUTH_PK_OK message */
1173         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1174
1175         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1176         packet_put_cstring(authctxt->server_user);
1177         packet_put_cstring(authctxt->service);
1178         packet_put_cstring(authctxt->method->name);
1179         packet_put_char(have_sig);
1180         if (!(datafellows & SSH_BUG_PKAUTH))
1181                 packet_put_cstring(key_ssh_name(id->key));
1182         packet_put_string(blob, bloblen);
1183         xfree(blob);
1184         packet_send();
1185         return 1;
1186 }
1187
1188 static Key *
1189 load_identity_file(char *filename)
1190 {
1191         Key *private;
1192         char prompt[300], *passphrase;
1193         int perm_ok, quit, i;
1194         struct stat st;
1195
1196         if (stat(filename, &st) < 0) {
1197                 debug3("no such identity: %s", filename);
1198                 return NULL;
1199         }
1200         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1201         if (!perm_ok)
1202                 return NULL;
1203         if (private == NULL) {
1204                 if (options.batch_mode)
1205                         return NULL;
1206                 snprintf(prompt, sizeof prompt,
1207                     "Enter passphrase for key '%.100s': ", filename);
1208                 for (i = 0; i < options.number_of_password_prompts; i++) {
1209                         passphrase = read_passphrase(prompt, 0);
1210                         if (strcmp(passphrase, "") != 0) {
1211                                 private = key_load_private_type(KEY_UNSPEC,
1212                                     filename, passphrase, NULL, NULL);
1213                                 quit = 0;
1214                         } else {
1215                                 debug2("no passphrase given, try next key");
1216                                 quit = 1;
1217                         }
1218                         memset(passphrase, 0, strlen(passphrase));
1219                         xfree(passphrase);
1220                         if (private != NULL || quit)
1221                                 break;
1222                         debug2("bad passphrase given, try again...");
1223                 }
1224         }
1225         return private;
1226 }
1227
1228 /*
1229  * try keys in the following order:
1230  *      1. agent keys that are found in the config file
1231  *      2. other agent keys
1232  *      3. keys that are only listed in the config file
1233  */
1234 static void
1235 pubkey_prepare(Authctxt *authctxt)
1236 {
1237         Identity *id;
1238         Idlist agent, files, *preferred;
1239         Key *key;
1240         AuthenticationConnection *ac;
1241         char *comment;
1242         int i, found;
1243
1244         TAILQ_INIT(&agent);     /* keys from the agent */
1245         TAILQ_INIT(&files);     /* keys from the config file */
1246         preferred = &authctxt->keys;
1247         TAILQ_INIT(preferred);  /* preferred order of keys */
1248
1249         /* list of keys stored in the filesystem */
1250         for (i = 0; i < options.num_identity_files; i++) {
1251                 key = options.identity_keys[i];
1252                 if (key && key->type == KEY_RSA1)
1253                         continue;
1254                 options.identity_keys[i] = NULL;
1255                 id = xcalloc(1, sizeof(*id));
1256                 id->key = key;
1257                 id->filename = xstrdup(options.identity_files[i]);
1258                 TAILQ_INSERT_TAIL(&files, id, next);
1259         }
1260         /* list of keys supported by the agent */
1261         if ((ac = ssh_get_authentication_connection())) {
1262                 for (key = ssh_get_first_identity(ac, &comment, 2);
1263                     key != NULL;
1264                     key = ssh_get_next_identity(ac, &comment, 2)) {
1265                         found = 0;
1266                         TAILQ_FOREACH(id, &files, next) {
1267                                 /* agent keys from the config file are preferred */
1268                                 if (key_equal(key, id->key)) {
1269                                         key_free(key);
1270                                         xfree(comment);
1271                                         TAILQ_REMOVE(&files, id, next);
1272                                         TAILQ_INSERT_TAIL(preferred, id, next);
1273                                         id->ac = ac;
1274                                         found = 1;
1275                                         break;
1276                                 }
1277                         }
1278                         if (!found && !options.identities_only) {
1279                                 id = xcalloc(1, sizeof(*id));
1280                                 id->key = key;
1281                                 id->filename = comment;
1282                                 id->ac = ac;
1283                                 TAILQ_INSERT_TAIL(&agent, id, next);
1284                         }
1285                 }
1286                 /* append remaining agent keys */
1287                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1288                         TAILQ_REMOVE(&agent, id, next);
1289                         TAILQ_INSERT_TAIL(preferred, id, next);
1290                 }
1291                 authctxt->agent = ac;
1292         }
1293         /* append remaining keys from the config file */
1294         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1295                 TAILQ_REMOVE(&files, id, next);
1296                 TAILQ_INSERT_TAIL(preferred, id, next);
1297         }
1298         TAILQ_FOREACH(id, preferred, next) {
1299                 debug2("key: %s (%p)", id->filename, id->key);
1300         }
1301 }
1302
1303 static void
1304 pubkey_cleanup(Authctxt *authctxt)
1305 {
1306         Identity *id;
1307
1308         if (authctxt->agent != NULL)
1309                 ssh_close_authentication_connection(authctxt->agent);
1310         for (id = TAILQ_FIRST(&authctxt->keys); id;
1311             id = TAILQ_FIRST(&authctxt->keys)) {
1312                 TAILQ_REMOVE(&authctxt->keys, id, next);
1313                 if (id->key)
1314                         key_free(id->key);
1315                 if (id->filename)
1316                         xfree(id->filename);
1317                 xfree(id);
1318         }
1319 }
1320
1321 int
1322 userauth_pubkey(Authctxt *authctxt)
1323 {
1324         Identity *id;
1325         int sent = 0;
1326
1327         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1328                 if (id->tried++)
1329                         return (0);
1330                 /* move key to the end of the queue */
1331                 TAILQ_REMOVE(&authctxt->keys, id, next);
1332                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1333                 /*
1334                  * send a test message if we have the public key. for
1335                  * encrypted keys we cannot do this and have to load the
1336                  * private key instead
1337                  */
1338                 if (id->key && id->key->type != KEY_RSA1) {
1339                         debug("Offering public key: %s", id->filename);
1340                         sent = send_pubkey_test(authctxt, id);
1341                 } else if (id->key == NULL) {
1342                         debug("Trying private key: %s", id->filename);
1343                         id->key = load_identity_file(id->filename);
1344                         if (id->key != NULL) {
1345                                 id->isprivate = 1;
1346                                 sent = sign_and_send_pubkey(authctxt, id);
1347                                 key_free(id->key);
1348                                 id->key = NULL;
1349                         }
1350                 }
1351                 if (sent)
1352                         return (sent);
1353         }
1354         return (0);
1355 }
1356
1357 /*
1358  * Send userauth request message specifying keyboard-interactive method.
1359  */
1360 int
1361 userauth_kbdint(Authctxt *authctxt)
1362 {
1363         static int attempt = 0;
1364
1365         if (attempt++ >= options.number_of_password_prompts)
1366                 return 0;
1367         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1368         if (attempt > 1 && !authctxt->info_req_seen) {
1369                 debug3("userauth_kbdint: disable: no info_req_seen");
1370                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1371                 return 0;
1372         }
1373
1374         debug2("userauth_kbdint");
1375         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1376         packet_put_cstring(authctxt->server_user);
1377         packet_put_cstring(authctxt->service);
1378         packet_put_cstring(authctxt->method->name);
1379         packet_put_cstring("");                                 /* lang */
1380         packet_put_cstring(options.kbd_interactive_devices ?
1381             options.kbd_interactive_devices : "");
1382         packet_send();
1383
1384         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1385         return 1;
1386 }
1387
1388 /*
1389  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1390  */
1391 void
1392 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1393 {
1394         Authctxt *authctxt = ctxt;
1395         char *name, *inst, *lang, *prompt, *response;
1396         u_int num_prompts, i;
1397         int echo = 0;
1398
1399         debug2("input_userauth_info_req");
1400
1401         if (authctxt == NULL)
1402                 fatal("input_userauth_info_req: no authentication context");
1403
1404         authctxt->info_req_seen = 1;
1405
1406         name = packet_get_string(NULL);
1407         inst = packet_get_string(NULL);
1408         lang = packet_get_string(NULL);
1409         if (strlen(name) > 0)
1410                 logit("%s", name);
1411         if (strlen(inst) > 0)
1412                 logit("%s", inst);
1413         xfree(name);
1414         xfree(inst);
1415         xfree(lang);
1416
1417         num_prompts = packet_get_int();
1418         /*
1419          * Begin to build info response packet based on prompts requested.
1420          * We commit to providing the correct number of responses, so if
1421          * further on we run into a problem that prevents this, we have to
1422          * be sure and clean this up and send a correct error response.
1423          */
1424         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1425         packet_put_int(num_prompts);
1426
1427         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1428         for (i = 0; i < num_prompts; i++) {
1429                 prompt = packet_get_string(NULL);
1430                 echo = packet_get_char();
1431
1432                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1433
1434                 packet_put_cstring(response);
1435                 memset(response, 0, strlen(response));
1436                 xfree(response);
1437                 xfree(prompt);
1438         }
1439         packet_check_eom(); /* done with parsing incoming message. */
1440
1441         packet_add_padding(64);
1442         packet_send();
1443 }
1444
1445 static int
1446 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1447     u_char *data, u_int datalen)
1448 {
1449         Buffer b;
1450         struct stat st;
1451         pid_t pid;
1452         int to[2], from[2], status, version = 2;
1453
1454         debug2("ssh_keysign called");
1455
1456         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1457                 error("ssh_keysign: no installed: %s", strerror(errno));
1458                 return -1;
1459         }
1460         if (fflush(stdout) != 0)
1461                 error("ssh_keysign: fflush: %s", strerror(errno));
1462         if (pipe(to) < 0) {
1463                 error("ssh_keysign: pipe: %s", strerror(errno));
1464                 return -1;
1465         }
1466         if (pipe(from) < 0) {
1467                 error("ssh_keysign: pipe: %s", strerror(errno));
1468                 return -1;
1469         }
1470         if ((pid = fork()) < 0) {
1471                 error("ssh_keysign: fork: %s", strerror(errno));
1472                 return -1;
1473         }
1474         if (pid == 0) {
1475                 permanently_drop_suid(getuid());
1476                 close(from[0]);
1477                 if (dup2(from[1], STDOUT_FILENO) < 0)
1478                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1479                 close(to[1]);
1480                 if (dup2(to[0], STDIN_FILENO) < 0)
1481                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1482                 close(from[1]);
1483                 close(to[0]);
1484                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1485                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1486                     strerror(errno));
1487         }
1488         close(from[1]);
1489         close(to[0]);
1490
1491         buffer_init(&b);
1492         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1493         buffer_put_string(&b, data, datalen);
1494         if (ssh_msg_send(to[1], version, &b) == -1)
1495                 fatal("ssh_keysign: couldn't send request");
1496
1497         if (ssh_msg_recv(from[0], &b) < 0) {
1498                 error("ssh_keysign: no reply");
1499                 buffer_free(&b);
1500                 return -1;
1501         }
1502         close(from[0]);
1503         close(to[1]);
1504
1505         while (waitpid(pid, &status, 0) < 0)
1506                 if (errno != EINTR)
1507                         break;
1508
1509         if (buffer_get_char(&b) != version) {
1510                 error("ssh_keysign: bad version");
1511                 buffer_free(&b);
1512                 return -1;
1513         }
1514         *sigp = buffer_get_string(&b, lenp);
1515         buffer_free(&b);
1516
1517         return 0;
1518 }
1519
1520 int
1521 userauth_hostbased(Authctxt *authctxt)
1522 {
1523         Key *private = NULL;
1524         Sensitive *sensitive = authctxt->sensitive;
1525         Buffer b;
1526         u_char *signature, *blob;
1527         char *chost, *pkalg, *p, myname[NI_MAXHOST];
1528         const char *service;
1529         u_int blen, slen;
1530         int ok, i, len, found = 0;
1531
1532         /* check for a useful key */
1533         for (i = 0; i < sensitive->nkeys; i++) {
1534                 private = sensitive->keys[i];
1535                 if (private && private->type != KEY_RSA1) {
1536                         found = 1;
1537                         /* we take and free the key */
1538                         sensitive->keys[i] = NULL;
1539                         break;
1540                 }
1541         }
1542         if (!found) {
1543                 debug("No more client hostkeys for hostbased authentication.");
1544                 return 0;
1545         }
1546         if (key_to_blob(private, &blob, &blen) == 0) {
1547                 key_free(private);
1548                 return 0;
1549         }
1550         /* figure out a name for the client host */
1551         p = NULL;
1552         if (packet_connection_is_on_socket())
1553                 p = get_local_name(packet_get_connection_in());
1554         if (p == NULL) {
1555                 if (gethostname(myname, sizeof(myname)) == -1) {
1556                         verbose("userauth_hostbased: gethostname: %s",
1557                             strerror(errno));
1558                 } else
1559                         p = xstrdup(myname);
1560         }
1561         if (p == NULL) {
1562                 error("userauth_hostbased: cannot get local ipaddr/name");
1563                 key_free(private);
1564                 xfree(blob);
1565                 return 0;
1566         }
1567         len = strlen(p) + 2;
1568         xasprintf(&chost, "%s.", p);
1569         debug2("userauth_hostbased: chost %s", chost);
1570         xfree(p);
1571
1572         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1573             authctxt->service;
1574         pkalg = xstrdup(key_ssh_name(private));
1575         buffer_init(&b);
1576         /* construct data */
1577         buffer_put_string(&b, session_id2, session_id2_len);
1578         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1579         buffer_put_cstring(&b, authctxt->server_user);
1580         buffer_put_cstring(&b, service);
1581         buffer_put_cstring(&b, authctxt->method->name);
1582         buffer_put_cstring(&b, pkalg);
1583         buffer_put_string(&b, blob, blen);
1584         buffer_put_cstring(&b, chost);
1585         buffer_put_cstring(&b, authctxt->local_user);
1586 #ifdef DEBUG_PK
1587         buffer_dump(&b);
1588 #endif
1589         if (sensitive->external_keysign)
1590                 ok = ssh_keysign(private, &signature, &slen,
1591                     buffer_ptr(&b), buffer_len(&b));
1592         else
1593                 ok = key_sign(private, &signature, &slen,
1594                     buffer_ptr(&b), buffer_len(&b));
1595         key_free(private);
1596         buffer_free(&b);
1597         if (ok != 0) {
1598                 error("key_sign failed");
1599                 xfree(chost);
1600                 xfree(pkalg);
1601                 xfree(blob);
1602                 return 0;
1603         }
1604         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1605         packet_put_cstring(authctxt->server_user);
1606         packet_put_cstring(authctxt->service);
1607         packet_put_cstring(authctxt->method->name);
1608         packet_put_cstring(pkalg);
1609         packet_put_string(blob, blen);
1610         packet_put_cstring(chost);
1611         packet_put_cstring(authctxt->local_user);
1612         packet_put_string(signature, slen);
1613         memset(signature, 's', slen);
1614         xfree(signature);
1615         xfree(chost);
1616         xfree(pkalg);
1617         xfree(blob);
1618
1619         packet_send();
1620         return 1;
1621 }
1622
1623 /* find auth method */
1624
1625 /*
1626  * given auth method name, if configurable options permit this method fill
1627  * in auth_ident field and return true, otherwise return false.
1628  */
1629 static int
1630 authmethod_is_enabled(Authmethod *method)
1631 {
1632         if (method == NULL)
1633                 return 0;
1634         /* return false if options indicate this method is disabled */
1635         if  (method->enabled == NULL || *method->enabled == 0)
1636                 return 0;
1637         /* return false if batch mode is enabled but method needs interactive mode */
1638         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1639                 return 0;
1640         return 1;
1641 }
1642
1643 static Authmethod *
1644 authmethod_lookup(const char *name)
1645 {
1646         Authmethod *method = NULL;
1647         if (name != NULL)
1648                 for (method = authmethods; method->name != NULL; method++)
1649                         if (strcmp(name, method->name) == 0)
1650                                 return method;
1651         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1652         return NULL;
1653 }
1654
1655 /* XXX internal state */
1656 static Authmethod *current = NULL;
1657 static char *supported = NULL;
1658 static char *preferred = NULL;
1659
1660 /*
1661  * Given the authentication method list sent by the server, return the
1662  * next method we should try.  If the server initially sends a nil list,
1663  * use a built-in default list.
1664  */
1665 static Authmethod *
1666 authmethod_get(char *authlist)
1667 {
1668         char *name = NULL;
1669         u_int next;
1670
1671         /* Use a suitable default if we're passed a nil list.  */
1672         if (authlist == NULL || strlen(authlist) == 0)
1673                 authlist = options.preferred_authentications;
1674
1675         if (supported == NULL || strcmp(authlist, supported) != 0) {
1676                 debug3("start over, passed a different list %s", authlist);
1677                 if (supported != NULL)
1678                         xfree(supported);
1679                 supported = xstrdup(authlist);
1680                 preferred = options.preferred_authentications;
1681                 debug3("preferred %s", preferred);
1682                 current = NULL;
1683         } else if (current != NULL && authmethod_is_enabled(current))
1684                 return current;
1685
1686         for (;;) {
1687                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1688                         debug("No more authentication methods to try.");
1689                         current = NULL;
1690                         return NULL;
1691                 }
1692                 preferred += next;
1693                 debug3("authmethod_lookup %s", name);
1694                 debug3("remaining preferred: %s", preferred);
1695                 if ((current = authmethod_lookup(name)) != NULL &&
1696                     authmethod_is_enabled(current)) {
1697                         debug3("authmethod_is_enabled %s", name);
1698                         debug("Next authentication method: %s", name);
1699                         return current;
1700                 }
1701         }
1702 }
1703
1704 static char *
1705 authmethods_get(void)
1706 {
1707         Authmethod *method = NULL;
1708         Buffer b;
1709         char *list;
1710
1711         buffer_init(&b);
1712         for (method = authmethods; method->name != NULL; method++) {
1713                 if (authmethod_is_enabled(method)) {
1714                         if (buffer_len(&b) > 0)
1715                                 buffer_append(&b, ",", 1);
1716                         buffer_append(&b, method->name, strlen(method->name));
1717                 }
1718         }
1719         buffer_append(&b, "\0", 1);
1720         list = xstrdup(buffer_ptr(&b));
1721         buffer_free(&b);
1722         return list;
1723 }