openssh/sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.162 2006/08/30 00:06:51 dtucker 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 <pwd.h>
  35 #include <signal.h>
  36 #include <stdarg.h>
  37 #include <stdio.h>
  38 #include <string.h>
  39 #include <unistd.h>
  40
  41 #include "openbsd-compat/sys-queue.h"
  42
  43 #include "xmalloc.h"
  44 #include "ssh.h"
  45 #include "ssh2.h"
  46 #include "buffer.h"
  47 #include "packet.h"
  48 #include "compat.h"
  49 #include "cipher.h"
  50 #include "key.h"
  51 #include "kex.h"
  52 #include "myproposal.h"
  53 #include "sshconnect.h"
  54 #include "authfile.h"
  55 #include "dh.h"
  56 #include "authfd.h"
  57 #include "log.h"
  58 #include "readconf.h"
  59 #include "misc.h"
  60 #include "match.h"
  61 #include "dispatch.h"
  62 #include "canohost.h"
  63 #include "msg.h"
  64 #include "pathnames.h"
  65 #include "uidswap.h"
  66
  67 #ifdef GSSAPI
  68 #include "ssh-gss.h"
  69 #endif
  70
  71 /* import */
  72 extern char *client_version_string;
  73 extern char *server_version_string;
  74 extern Options options;
  75 extern Kex *xxx_kex;
  76
  77 /* tty_flag is set in ssh.c. use this in ssh_userauth2 */
  78 /* if it is set then prevent the switch to the null cipher */
  79
  80 extern int tty_flag;
  81
  82 /*
  83  * SSH2 key exchange
  84  */
  85
  86 u_char *session_id2 = NULL;
  87 u_int session_id2_len = 0;
  88
  89 char *xxx_host;
  90 struct sockaddr *xxx_hostaddr;
  91
  92 Kex *xxx_kex = NULL;
  93
  94 static int
  95 verify_host_key_callback(Key *hostkey)
  96 {
  97         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
  98                 fatal("Host key verification failed.");
  99         return 0;
 100 }
 101
 102 void
 103 ssh_kex2(char *host, struct sockaddr *hostaddr)
 104 {
 105         Kex *kex;
 106
 107 #ifdef GSSAPI
 108         char *orig = NULL, *gss = NULL;
 109         char *gss_host = NULL;
 110 #endif
 111
 112         xxx_host = host;
 113         xxx_hostaddr = hostaddr;
 114
 115 #ifdef GSSAPI
 116         if (options.gss_keyex) {
 117                 /* Add the GSSAPI mechanisms currently supported on this
 118                  * client to the key exchange algorithm proposal */
 119                 orig = myproposal[PROPOSAL_KEX_ALGS];
 120
 121                 if (options.gss_trust_dns)
 122                         gss_host = (char *)get_canonical_hostname(1);
 123                 else
 124                         gss_host = host;
 125
 126                 gss = ssh_gssapi_client_mechanisms(gss_host);
 127                 if (gss) {
 128                         debug("Offering GSSAPI proposal: %s", gss);
 129                         xasprintf(&myproposal[PROPOSAL_KEX_ALGS],
 130                             "%s,%s", gss, orig);
 131                 }
 132         }
 133 #endif
 134
 135         if (options.ciphers == (char *)-1) {
 136                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 137                 options.ciphers = NULL;
 138         }
 139         if (options.ciphers != NULL) {
 140                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 141                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 142         }
 143
 144         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 145             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 146         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 147             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 148         if (options.compression) {
 149                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 150                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 151         } else {
 152                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 153                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 154         }
 155         if (options.macs != NULL) {
 156                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 157                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 158         }
 159         if (options.hostkeyalgorithms != NULL)
 160                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 161                     options.hostkeyalgorithms;
 162
 163 #ifdef GSSAPI
 164         /* If we've got GSSAPI algorithms, then we also support the
 165          * 'null' hostkey, as a last resort */
 166         if (options.gss_keyex && gss) {
 167                 orig = myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
 168                 xasprintf(&myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS],
 169                     "%s,null", orig);
 170         }
 171 #endif
 172
 173         if (options.rekey_limit)
 174                 packet_set_rekey_limit(options.rekey_limit);
 175
 176         /* start key exchange */
 177         kex = kex_setup(myproposal);
 178         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 179         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 180         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 181         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 182 #ifdef GSSAPI
 183         kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client;
 184         kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_client;
 185         kex->kex[KEX_GSS_GEX_SHA1] = kexgss_client;
 186 #endif
 187         kex->client_version_string=client_version_string;
 188         kex->server_version_string=server_version_string;
 189         kex->verify_host_key=&verify_host_key_callback;
 190
 191 #ifdef GSSAPI
 192         kex->gss_deleg_creds = options.gss_deleg_creds;
 193         kex->gss_trust_dns = options.gss_trust_dns;
 194         kex->gss_host = gss_host;
 195 #endif
 196
 197         xxx_kex = kex;
 198
 199         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 200
 201         session_id2 = kex->session_id;
 202         session_id2_len = kex->session_id_len;
 203
 204 #ifdef DEBUG_KEXDH
 205         /* send 1st encrypted/maced/compressed message */
 206         packet_start(SSH2_MSG_IGNORE);
 207         packet_put_cstring("markus");
 208         packet_send();
 209         packet_write_wait();
 210 #endif
 211 }
 212
 213 /*
 214  * Authenticate user
 215  */
 216
 217 typedef struct Authctxt Authctxt;
 218 typedef struct Authmethod Authmethod;
 219 typedef struct identity Identity;
 220 typedef struct idlist Idlist;
 221
 222 struct identity {
 223         TAILQ_ENTRY(identity) next;
 224         AuthenticationConnection *ac;   /* set if agent supports key */
 225         Key     *key;                   /* public/private key */
 226         char    *filename;              /* comment for agent-only keys */
 227         int     tried;
 228         int     isprivate;              /* key points to the private key */
 229 };
 230 TAILQ_HEAD(idlist, identity);
 231
 232 struct Authctxt {
 233         const char *server_user;
 234         const char *local_user;
 235         const char *host;
 236         const char *service;
 237         Authmethod *method;
 238         int success;
 239         char *authlist;
 240         /* pubkey */
 241         Idlist keys;
 242         AuthenticationConnection *agent;
 243         /* hostbased */
 244         Sensitive *sensitive;
 245         /* kbd-interactive */
 246         int info_req_seen;
 247         /* generic */
 248         void *methoddata;
 249 };
 250 struct Authmethod {
 251         char    *name;          /* string to compare against server's list */
 252         int     (*userauth)(Authctxt *authctxt);
 253         int     *enabled;       /* flag in option struct that enables method */
 254         int     *batch_flag;    /* flag in option struct that disables method */
 255 };
 256
 257 void    input_userauth_success(int, u_int32_t, void *);
 258 void    input_userauth_failure(int, u_int32_t, void *);
 259 void    input_userauth_banner(int, u_int32_t, void *);
 260 void    input_userauth_error(int, u_int32_t, void *);
 261 void    input_userauth_info_req(int, u_int32_t, void *);
 262 void    input_userauth_pk_ok(int, u_int32_t, void *);
 263 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 264
 265 int     userauth_none(Authctxt *);
 266 int     userauth_pubkey(Authctxt *);
 267 int     userauth_passwd(Authctxt *);
 268 int     userauth_kbdint(Authctxt *);
 269 int     userauth_hostbased(Authctxt *);
 270 int     userauth_kerberos(Authctxt *);
 271
 272 #ifdef GSSAPI
 273 int     userauth_external(Authctxt *authctxt);
 274 int     userauth_gssapi(Authctxt *authctxt);
 275 int     userauth_gssapi_with_mic(Authctxt *authctxt);
 276 int     userauth_gssapi_without_mic(Authctxt *authctxt);
 277 void    input_gssapi_response(int type, u_int32_t, void *);
 278 void    input_gssapi_token(int type, u_int32_t, void *);
 279 void    input_gssapi_hash(int type, u_int32_t, void *);
 280 void    input_gssapi_error(int, u_int32_t, void *);
 281 void    input_gssapi_errtok(int, u_int32_t, void *);
 282 int     userauth_gsskeyex(Authctxt *authctxt);
 283 #endif
 284
 285 void    userauth(Authctxt *, char *);
 286
 287 static int sign_and_send_pubkey(Authctxt *, Identity *);
 288 static void pubkey_prepare(Authctxt *);
 289 static void pubkey_cleanup(Authctxt *);
 290 static Key *load_identity_file(char *);
 291
 292 static Authmethod *authmethod_get(char *authlist);
 293 static Authmethod *authmethod_lookup(const char *name);
 294 static char *authmethods_get(void);
 295
 296 Authmethod authmethods[] = {
 297 #ifdef GSSAPI
 298         {"gssapi-keyex",
 299                 userauth_gsskeyex,
 300                 &options.gss_authentication,
 301                 NULL},
 302         {"external-keyx",
 303                 userauth_external,
 304                 &options.gss_authentication,
 305                 NULL},
 306         {"gssapi-with-mic",
 307                 userauth_gssapi,
 308                 &options.gss_authentication,
 309                 NULL},
 310         {"gssapi",
 311                 userauth_gssapi,
 312                 &options.gss_authentication,
 313                 NULL},
 314 #endif
 315         {"hostbased",
 316                 userauth_hostbased,
 317                 &options.hostbased_authentication,
 318                 NULL},
 319         {"publickey",
 320                 userauth_pubkey,
 321                 &options.pubkey_authentication,
 322                 NULL},
 323         {"keyboard-interactive",
 324                 userauth_kbdint,
 325                 &options.kbd_interactive_authentication,
 326                 &options.batch_mode},
 327         {"password",
 328                 userauth_passwd,
 329                 &options.password_authentication,
 330                 &options.batch_mode},
 331         {"none",
 332                 userauth_none,
 333                 NULL,
 334                 NULL},
 335         {NULL, NULL, NULL, NULL}
 336 };
 337
 338 void
 339 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 340     Sensitive *sensitive)
 341 {
 342         Authctxt authctxt;
 343         int type;
 344
 345         if (options.challenge_response_authentication)
 346                 options.kbd_interactive_authentication = 1;
 347
 348         packet_start(SSH2_MSG_SERVICE_REQUEST);
 349         packet_put_cstring("ssh-userauth");
 350         packet_send();
 351         debug("SSH2_MSG_SERVICE_REQUEST sent");
 352         packet_write_wait();
 353         type = packet_read();
 354         if (type != SSH2_MSG_SERVICE_ACCEPT)
 355                 fatal("Server denied authentication request: %d", type);
 356         if (packet_remaining() > 0) {
 357                 char *reply = packet_get_string(NULL);
 358                 debug2("service_accept: %s", reply);
 359                 xfree(reply);
 360         } else {
 361                 debug2("buggy server: service_accept w/o service");
 362         }
 363         packet_check_eom();
 364         debug("SSH2_MSG_SERVICE_ACCEPT received");
 365
 366         if (options.preferred_authentications == NULL)
 367                 options.preferred_authentications = authmethods_get();
 368
 369         /* setup authentication context */
 370         memset(&authctxt, 0, sizeof(authctxt));
 371         pubkey_prepare(&authctxt);
 372         authctxt.server_user = server_user;
 373         authctxt.local_user = local_user;
 374         authctxt.host = host;
 375         authctxt.service = "ssh-connection";            /* service name */
 376         authctxt.success = 0;
 377         authctxt.method = authmethod_lookup("none");
 378         authctxt.authlist = NULL;
 379         authctxt.methoddata = NULL;
 380         authctxt.sensitive = sensitive;
 381         authctxt.info_req_seen = 0;
 382         if (authctxt.method == NULL)
 383                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 384
 385         /* initial userauth request */
 386         userauth_none(&authctxt);
 387
 388         dispatch_init(&input_userauth_error);
 389         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 390         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 391         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 392         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 393
 394         pubkey_cleanup(&authctxt);
 395         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 396
 397         /* if the user wants to use the none cipher do it */
 398         /* post authentication and only if the right conditions are met */
 399         /* both of the NONE commands must be true and there must be no */
 400         /* tty allocated */
 401         if ((options.none_switch == 1) && (options.none_enabled == 1))
 402         {
 403                 if (!tty_flag) /* no null on tty sessions */
 404                 {
 405                         debug("Requesting none rekeying...");
 406                         myproposal[PROPOSAL_ENC_ALGS_STOC] = "none";
 407                         myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none";
 408                         kex_prop2buf(&xxx_kex->my,myproposal);
 409                         packet_request_rekeying();
 410                         fprintf(stderr, "WARNING: ENABLED NONE CIPHER\n");
 411                 }
 412                 else
 413                 {
 414                         /* requested NONE cipher when in a tty */
 415                         debug("Cannot switch to NONE cipher with tty allocated");
 416                         fprintf(stderr, "NONE cipher switch disabled when a TTY is allocated\n");
 417                 }
 418         }
 419         debug("Authentication succeeded (%s).", authctxt.method->name);
 420 }
 421
 422 void
 423 userauth(Authctxt *authctxt, char *authlist)
 424 {
 425         if (authctxt->methoddata) {
 426                 xfree(authctxt->methoddata);
 427                 authctxt->methoddata = NULL;
 428         }
 429         if (authlist == NULL) {
 430                 authlist = authctxt->authlist;
 431         } else {
 432                 if (authctxt->authlist)
 433                         xfree(authctxt->authlist);
 434                 authctxt->authlist = authlist;
 435         }
 436         for (;;) {
 437                 Authmethod *method = authmethod_get(authlist);
 438                 if (method == NULL)
 439                         fatal("Permission denied (%s).", authlist);
 440                 authctxt->method = method;
 441
 442                 /* reset the per method handler */
 443                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 444                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 445
 446                 /* and try new method */
 447                 if (method->userauth(authctxt) != 0) {
 448                         debug2("we sent a %s packet, wait for reply", method->name);
 449                         break;
 450                 } else {
 451                         debug2("we did not send a packet, disable method");
 452                         method->enabled = NULL;
 453                 }
 454         }
 455 }
 456
 457 void
 458 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 459 {
 460         fatal("input_userauth_error: bad message during authentication: "
 461             "type %d", type);
 462 }
 463
 464 void
 465 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 466 {
 467         char *msg, *lang;
 468
 469         debug3("input_userauth_banner");
 470         msg = packet_get_string(NULL);
 471         lang = packet_get_string(NULL);
 472         if (options.log_level >= SYSLOG_LEVEL_INFO)
 473                 fprintf(stderr, "%s", msg);
 474         xfree(msg);
 475         xfree(lang);
 476 }
 477
 478 void
 479 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 480 {
 481         Authctxt *authctxt = ctxt;
 482         if (authctxt == NULL)
 483                 fatal("input_userauth_success: no authentication context");
 484         if (authctxt->authlist) {
 485                 xfree(authctxt->authlist);
 486                 authctxt->authlist = NULL;
 487         }
 488         if (authctxt->methoddata) {
 489                 xfree(authctxt->methoddata);
 490                 authctxt->methoddata = NULL;
 491         }
 492         authctxt->success = 1;                  /* break out */
 493 }
 494
 495 void
 496 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 497 {
 498         Authctxt *authctxt = ctxt;
 499         char *authlist = NULL;
 500         int partial;
 501
 502         if (authctxt == NULL)
 503                 fatal("input_userauth_failure: no authentication context");
 504
 505         authlist = packet_get_string(NULL);
 506         partial = packet_get_char();
 507         packet_check_eom();
 508
 509         if (partial != 0)
 510                 logit("Authenticated with partial success.");
 511         debug("Authentications that can continue: %s", authlist);
 512
 513         userauth(authctxt, authlist);
 514 }
 515 void
 516 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 517 {
 518         Authctxt *authctxt = ctxt;
 519         Key *key = NULL;
 520         Identity *id = NULL;
 521         Buffer b;
 522         int pktype, sent = 0;
 523         u_int alen, blen;
 524         char *pkalg, *fp;
 525         u_char *pkblob;
 526
 527         if (authctxt == NULL)
 528                 fatal("input_userauth_pk_ok: no authentication context");
 529         if (datafellows & SSH_BUG_PKOK) {
 530                 /* this is similar to SSH_BUG_PKAUTH */
 531                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 532                 pkblob = packet_get_string(&blen);
 533                 buffer_init(&b);
 534                 buffer_append(&b, pkblob, blen);
 535                 pkalg = buffer_get_string(&b, &alen);
 536                 buffer_free(&b);
 537         } else {
 538                 pkalg = packet_get_string(&alen);
 539                 pkblob = packet_get_string(&blen);
 540         }
 541         packet_check_eom();
 542
 543         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 544
 545         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 546                 debug("unknown pkalg %s", pkalg);
 547                 goto done;
 548         }
 549         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 550                 debug("no key from blob. pkalg %s", pkalg);
 551                 goto done;
 552         }
 553         if (key->type != pktype) {
 554                 error("input_userauth_pk_ok: type mismatch "
 555                     "for decoded key (received %d, expected %d)",
 556                     key->type, pktype);
 557                 goto done;
 558         }
 559         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 560         debug2("input_userauth_pk_ok: fp %s", fp);
 561         xfree(fp);
 562
 563         /*
 564          * search keys in the reverse order, because last candidate has been
 565          * moved to the end of the queue.  this also avoids confusion by
 566          * duplicate keys
 567          */
 568         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 569                 if (key_equal(key, id->key)) {
 570                         sent = sign_and_send_pubkey(authctxt, id);
 571                         break;
 572                 }
 573         }
 574 done:
 575         if (key != NULL)
 576                 key_free(key);
 577         xfree(pkalg);
 578         xfree(pkblob);
 579
 580         /* try another method if we did not send a packet */
 581         if (sent == 0)
 582                 userauth(authctxt, NULL);
 583 }
 584
 585 #ifdef GSSAPI
 586 int
 587 userauth_gssapi(Authctxt *authctxt)
 588 {
 589         Gssctxt *gssctxt = NULL;
 590         static gss_OID_set gss_supported = NULL;
 591         static u_int mech = 0;
 592         OM_uint32 min;
 593         int ok = 0;
 594         char *gss_host = NULL;
 595
 596         if (!options.gss_authentication) {
 597                 verbose("GSSAPI authentication disabled.");
 598                 return 0;
 599         }
 600
 601         if (options.gss_trust_dns)
 602                 gss_host = (char *)get_canonical_hostname(1);
 603         else
 604                 gss_host = (char *)authctxt->host;
 605
 606         /* Try one GSSAPI method at a time, rather than sending them all at
 607          * once. */
 608
 609         if (gss_supported == NULL)
 610                 gss_indicate_mechs(&min, &gss_supported);
 611
 612         /* Check to see if the mechanism is usable before we offer it */
 613         while (mech < gss_supported->count && !ok) {
 614                 /* My DER encoding requires length<128 */
 615                 if (gss_supported->elements[mech].length < 128 &&
 616                     ssh_gssapi_check_mechanism(&gssctxt,
 617                     &gss_supported->elements[mech], gss_host)) {
 618                         ok = 1; /* Mechanism works */
 619                 } else {
 620                         mech++;
 621                 }
 622         }
 623
 624         if (!ok)
 625                 return 0;
 626
 627         authctxt->methoddata=(void *)gssctxt;
 628
 629         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 630         packet_put_cstring(authctxt->server_user);
 631         packet_put_cstring(authctxt->service);
 632         packet_put_cstring(authctxt->method->name);
 633
 634         packet_put_int(1);
 635
 636         packet_put_int((gss_supported->elements[mech].length) + 2);
 637         packet_put_char(SSH_GSS_OIDTYPE);
 638         packet_put_char(gss_supported->elements[mech].length);
 639         packet_put_raw(gss_supported->elements[mech].elements,
 640             gss_supported->elements[mech].length);
 641
 642         packet_send();
 643
 644         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 645         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 646         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 647         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 648
 649         mech++; /* Move along to next candidate */
 650
 651         return 1;
 652 }
 653
 654 static OM_uint32
 655 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 656 {
 657         Authctxt *authctxt = ctxt;
 658         Gssctxt *gssctxt = authctxt->methoddata;
 659         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 660         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 661         gss_buffer_desc gssbuf;
 662         OM_uint32 status, ms, flags;
 663         Buffer b;
 664
 665         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 666             recv_tok, &send_tok, &flags);
 667
 668         if (send_tok.length > 0) {
 669                 if (GSS_ERROR(status))
 670                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 671                 else
 672                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 673
 674                 packet_put_string(send_tok.value, send_tok.length);
 675                 packet_send();
 676                 gss_release_buffer(&ms, &send_tok);
 677         }
 678
 679         if (status == GSS_S_COMPLETE) {
 680                 /* send either complete or MIC, depending on mechanism */
 681                 if (strcmp(authctxt->method->name,"gssapi")==0 ||
 682                     (!(flags & GSS_C_INTEG_FLAG))) {
 683                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 684                         packet_send();
 685                 } else {
 686                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 687                             authctxt->service, "gssapi-with-mic");
 688
 689                         gssbuf.value = buffer_ptr(&b);
 690                         gssbuf.length = buffer_len(&b);
 691
 692                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 693
 694                         if (!GSS_ERROR(status)) {
 695                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 696                                 packet_put_string(mic.value, mic.length);
 697
 698                                 packet_send();
 699                         }
 700
 701                         buffer_free(&b);
 702                         gss_release_buffer(&ms, &mic);
 703                 }
 704         }
 705
 706         return status;
 707 }
 708
 709 void
 710 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 711 {
 712         Authctxt *authctxt = ctxt;
 713         Gssctxt *gssctxt;
 714         u_int oidlen;
 715         u_char *oidv;
 716
 717         if (authctxt == NULL)
 718                 fatal("input_gssapi_response: no authentication context");
 719         gssctxt = authctxt->methoddata;
 720
 721         /* Setup our OID */
 722         oidv = packet_get_string(&oidlen);
 723
 724         if (oidlen <= 2 ||
 725             oidv[0] != SSH_GSS_OIDTYPE ||
 726             oidv[1] != oidlen - 2) {
 727                 xfree(oidv);
 728                 debug("Badly encoded mechanism OID received");
 729                 userauth(authctxt, NULL);
 730                 return;
 731         }
 732
 733         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 734                 fatal("Server returned different OID than expected");
 735
 736         packet_check_eom();
 737
 738         xfree(oidv);
 739
 740         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 741                 /* Start again with next method on list */
 742                 debug("Trying to start again");
 743                 userauth(authctxt, NULL);
 744                 return;
 745         }
 746 }
 747
 748 void
 749 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 750 {
 751         Authctxt *authctxt = ctxt;
 752         gss_buffer_desc recv_tok;
 753         OM_uint32 status;
 754         u_int slen;
 755
 756         if (authctxt == NULL)
 757                 fatal("input_gssapi_response: no authentication context");
 758
 759         recv_tok.value = packet_get_string(&slen);
 760         recv_tok.length = slen; /* safe typecast */
 761
 762         packet_check_eom();
 763
 764         status = process_gssapi_token(ctxt, &recv_tok);
 765
 766         xfree(recv_tok.value);
 767
 768         if (GSS_ERROR(status)) {
 769                 /* Start again with the next method in the list */
 770                 userauth(authctxt, NULL);
 771                 return;
 772         }
 773 }
 774
 775 void
 776 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 777 {
 778         Authctxt *authctxt = ctxt;
 779         Gssctxt *gssctxt;
 780         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 781         gss_buffer_desc recv_tok;
 782         OM_uint32 status, ms;
 783         u_int len;
 784
 785         if (authctxt == NULL)
 786                 fatal("input_gssapi_response: no authentication context");
 787         gssctxt = authctxt->methoddata;
 788
 789         recv_tok.value = packet_get_string(&len);
 790         recv_tok.length = len;
 791
 792         packet_check_eom();
 793
 794         /* Stick it into GSSAPI and see what it says */
 795         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 796             &recv_tok, &send_tok, NULL);
 797
 798         xfree(recv_tok.value);
 799         gss_release_buffer(&ms, &send_tok);
 800
 801         /* Server will be returning a failed packet after this one */
 802 }
 803
 804 void
 805 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 806 {
 807         OM_uint32 maj, min;
 808         char *msg;
 809         char *lang;
 810
 811         maj=packet_get_int();
 812         min=packet_get_int();
 813         msg=packet_get_string(NULL);
 814         lang=packet_get_string(NULL);
 815
 816         packet_check_eom();
 817
 818         debug("Server GSSAPI Error:\n%s", msg);
 819         xfree(msg);
 820         xfree(lang);
 821 }
 822
 823 #ifdef GSI
 824 extern
 825 const gss_OID_desc * const              gss_mech_globus_gssapi_openssl;
 826 #define is_gsi_oid(oid) \
 827   (oid->length == gss_mech_globus_gssapi_openssl->length && \
 828    (memcmp(oid->elements, gss_mech_globus_gssapi_openssl->elements, \
 829            oid->length) == 0))
 830 #endif
 831
 832 int
 833 userauth_external(Authctxt *authctxt)
 834 {
 835         static int attempt = 0;
 836
 837         if (attempt++ >= 1)
 838                 return 0;
 839
 840         /* The client MUST NOT try this method if initial key exchange
 841            was not performed using a GSSAPI-based key exchange
 842            method. */
 843         if (gss_kex_context == NULL) {
 844                 debug2("gsskex not performed, skipping external-keyx");
 845                 return 0;
 846         }
 847
 848         debug2("userauth_external");
 849         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 850 #ifdef GSI
 851         if (options.implicit && is_gsi_oid(gss_kex_context->oid)) {
 852         packet_put_cstring("");
 853         } else {
 854 #endif
 855         packet_put_cstring(authctxt->server_user);
 856 #ifdef GSI
 857         }
 858 #endif
 859         packet_put_cstring(authctxt->service);
 860         packet_put_cstring(authctxt->method->name);
 861         packet_send();
 862         packet_write_wait();
 863         return 1;
 864 }
 865 int
 866 userauth_gsskeyex(Authctxt *authctxt)
 867 {
 868         Buffer b;
 869         gss_buffer_desc gssbuf;
 870         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 871         OM_uint32 ms;
 872
 873         static int attempt = 0;
 874         if (attempt++ >= 1)
 875                 return (0);
 876
 877         if (gss_kex_context == NULL) {
 878                 debug("No valid Key exchange context");
 879                 return (0);
 880         }
 881
 882 #ifdef GSI
 883         if (options.implicit && is_gsi_oid(gss_kex_context->oid)) {
 884         ssh_gssapi_buildmic(&b, "", authctxt->service, "gssapi-keyex");
 885         } else {
 886 #endif
 887         ssh_gssapi_buildmic(&b, authctxt->server_user, authctxt->service,
 888             "gssapi-keyex");
 889 #ifdef GSI
 890         }
 891 #endif
 892
 893         gssbuf.value = buffer_ptr(&b);
 894         gssbuf.length = buffer_len(&b);
 895
 896         if (GSS_ERROR(ssh_gssapi_sign(gss_kex_context, &gssbuf, &mic))) {
 897                 buffer_free(&b);
 898                 return (0);
 899         }
 900
 901         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 902 #ifdef GSI
 903         if (options.implicit && is_gsi_oid(gss_kex_context->oid)) {
 904         packet_put_cstring("");
 905         } else {
 906 #endif
 907         packet_put_cstring(authctxt->server_user);
 908 #ifdef GSI
 909         }
 910 #endif
 911         packet_put_cstring(authctxt->service);
 912         packet_put_cstring(authctxt->method->name);
 913         packet_put_string(mic.value, mic.length);
 914         packet_send();
 915
 916         buffer_free(&b);
 917         gss_release_buffer(&ms, &mic);
 918
 919         return (1);
 920 }
 921
 922 #endif /* GSSAPI */
 923
 924 int
 925 userauth_none(Authctxt *authctxt)
 926 {
 927         /* initial userauth request */
 928         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 929         packet_put_cstring(authctxt->server_user);
 930         packet_put_cstring(authctxt->service);
 931         packet_put_cstring(authctxt->method->name);
 932         packet_send();
 933         return 1;
 934 }
 935
 936 int
 937 userauth_passwd(Authctxt *authctxt)
 938 {
 939         static int attempt = 0;
 940         char prompt[150];
 941         char *password;
 942
 943         if (attempt++ >= options.number_of_password_prompts)
 944                 return 0;
 945
 946         if (attempt != 1)
 947                 error("Permission denied, please try again.");
 948
 949         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 950             authctxt->server_user, authctxt->host);
 951         password = read_passphrase(prompt, 0);
 952         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 953         packet_put_cstring(authctxt->server_user);
 954         packet_put_cstring(authctxt->service);
 955         packet_put_cstring(authctxt->method->name);
 956         packet_put_char(0);
 957         packet_put_cstring(password);
 958         memset(password, 0, strlen(password));
 959         xfree(password);
 960         packet_add_padding(64);
 961         packet_send();
 962
 963         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 964             &input_userauth_passwd_changereq);
 965
 966         return 1;
 967 }
 968 /*
 969  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 970  */
 971 void
 972 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 973 {
 974         Authctxt *authctxt = ctxt;
 975         char *info, *lang, *password = NULL, *retype = NULL;
 976         char prompt[150];
 977
 978         debug2("input_userauth_passwd_changereq");
 979
 980         if (authctxt == NULL)
 981                 fatal("input_userauth_passwd_changereq: "
 982                     "no authentication context");
 983
 984         info = packet_get_string(NULL);
 985         lang = packet_get_string(NULL);
 986         if (strlen(info) > 0)
 987                 logit("%s", info);
 988         xfree(info);
 989         xfree(lang);
 990         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 991         packet_put_cstring(authctxt->server_user);
 992         packet_put_cstring(authctxt->service);
 993         packet_put_cstring(authctxt->method->name);
 994         packet_put_char(1);                     /* additional info */
 995         snprintf(prompt, sizeof(prompt),
 996             "Enter %.30s@%.128s's old password: ",
 997             authctxt->server_user, authctxt->host);
 998         password = read_passphrase(prompt, 0);
 999         packet_put_cstring(password);
1000         memset(password, 0, strlen(password));
1001         xfree(password);
1002         password = NULL;
1003         while (password == NULL) {
1004                 snprintf(prompt, sizeof(prompt),
1005                     "Enter %.30s@%.128s's new password: ",
1006                     authctxt->server_user, authctxt->host);
1007                 password = read_passphrase(prompt, RP_ALLOW_EOF);
1008                 if (password == NULL) {
1009                         /* bail out */
1010                         return;
1011                 }
1012                 snprintf(prompt, sizeof(prompt),
1013                     "Retype %.30s@%.128s's new password: ",
1014                     authctxt->server_user, authctxt->host);
1015                 retype = read_passphrase(prompt, 0);
1016                 if (strcmp(password, retype) != 0) {
1017                         memset(password, 0, strlen(password));
1018                         xfree(password);
1019                         logit("Mismatch; try again, EOF to quit.");
1020                         password = NULL;
1021                 }
1022                 memset(retype, 0, strlen(retype));
1023                 xfree(retype);
1024         }
1025         packet_put_cstring(password);
1026         memset(password, 0, strlen(password));
1027         xfree(password);
1028         packet_add_padding(64);
1029         packet_send();
1030
1031         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
1032             &input_userauth_passwd_changereq);
1033 }
1034
1035 static int
1036 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
1037     u_char *data, u_int datalen)
1038 {
1039         Key *prv;
1040         int ret;
1041
1042         /* the agent supports this key */
1043         if (id->ac)
1044                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1045                     data, datalen));
1046         /*
1047          * we have already loaded the private key or
1048          * the private key is stored in external hardware
1049          */
1050         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1051                 return (key_sign(id->key, sigp, lenp, data, datalen));
1052         /* load the private key from the file */
1053         if ((prv = load_identity_file(id->filename)) == NULL)
1054                 return (-1);
1055         ret = key_sign(prv, sigp, lenp, data, datalen);
1056         key_free(prv);
1057         return (ret);
1058 }
1059
1060 static int
1061 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1062 {
1063         Buffer b;
1064         u_char *blob, *signature;
1065         u_int bloblen, slen;
1066         u_int skip = 0;
1067         int ret = -1;
1068         int have_sig = 1;
1069
1070         debug3("sign_and_send_pubkey");
1071
1072         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1073                 /* we cannot handle this key */
1074                 debug3("sign_and_send_pubkey: cannot handle key");
1075                 return 0;
1076         }
1077         /* data to be signed */
1078         buffer_init(&b);
1079         if (datafellows & SSH_OLD_SESSIONID) {
1080                 buffer_append(&b, session_id2, session_id2_len);
1081                 skip = session_id2_len;
1082         } else {
1083                 buffer_put_string(&b, session_id2, session_id2_len);
1084                 skip = buffer_len(&b);
1085         }
1086         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1087         buffer_put_cstring(&b, authctxt->server_user);
1088         buffer_put_cstring(&b,
1089             datafellows & SSH_BUG_PKSERVICE ?
1090             "ssh-userauth" :
1091             authctxt->service);
1092         if (datafellows & SSH_BUG_PKAUTH) {
1093                 buffer_put_char(&b, have_sig);
1094         } else {
1095                 buffer_put_cstring(&b, authctxt->method->name);
1096                 buffer_put_char(&b, have_sig);
1097                 buffer_put_cstring(&b, key_ssh_name(id->key));
1098         }
1099         buffer_put_string(&b, blob, bloblen);
1100
1101         /* generate signature */
1102         ret = identity_sign(id, &signature, &slen,
1103             buffer_ptr(&b), buffer_len(&b));
1104         if (ret == -1) {
1105                 xfree(blob);
1106                 buffer_free(&b);
1107                 return 0;
1108         }
1109 #ifdef DEBUG_PK
1110         buffer_dump(&b);
1111 #endif
1112         if (datafellows & SSH_BUG_PKSERVICE) {
1113                 buffer_clear(&b);
1114                 buffer_append(&b, session_id2, session_id2_len);
1115                 skip = session_id2_len;
1116                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1117                 buffer_put_cstring(&b, authctxt->server_user);
1118                 buffer_put_cstring(&b, authctxt->service);
1119                 buffer_put_cstring(&b, authctxt->method->name);
1120                 buffer_put_char(&b, have_sig);
1121                 if (!(datafellows & SSH_BUG_PKAUTH))
1122                         buffer_put_cstring(&b, key_ssh_name(id->key));
1123                 buffer_put_string(&b, blob, bloblen);
1124         }
1125         xfree(blob);
1126
1127         /* append signature */
1128         buffer_put_string(&b, signature, slen);
1129         xfree(signature);
1130
1131         /* skip session id and packet type */
1132         if (buffer_len(&b) < skip + 1)
1133                 fatal("userauth_pubkey: internal error");
1134         buffer_consume(&b, skip + 1);
1135
1136         /* put remaining data from buffer into packet */
1137         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1138         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1139         buffer_free(&b);
1140         packet_send();
1141
1142         return 1;
1143 }
1144
1145 static int
1146 send_pubkey_test(Authctxt *authctxt, Identity *id)
1147 {
1148         u_char *blob;
1149         u_int bloblen, have_sig = 0;
1150
1151         debug3("send_pubkey_test");
1152
1153         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1154                 /* we cannot handle this key */
1155                 debug3("send_pubkey_test: cannot handle key");
1156                 return 0;
1157         }
1158         /* register callback for USERAUTH_PK_OK message */
1159         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1160
1161         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1162         packet_put_cstring(authctxt->server_user);
1163         packet_put_cstring(authctxt->service);
1164         packet_put_cstring(authctxt->method->name);
1165         packet_put_char(have_sig);
1166         if (!(datafellows & SSH_BUG_PKAUTH))
1167                 packet_put_cstring(key_ssh_name(id->key));
1168         packet_put_string(blob, bloblen);
1169         xfree(blob);
1170         packet_send();
1171         return 1;
1172 }
1173
1174 static Key *
1175 load_identity_file(char *filename)
1176 {
1177         Key *private;
1178         char prompt[300], *passphrase;
1179         int perm_ok, quit, i;
1180         struct stat st;
1181
1182         if (stat(filename, &st) < 0) {
1183                 debug3("no such identity: %s", filename);
1184                 return NULL;
1185         }
1186         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1187         if (!perm_ok)
1188                 return NULL;
1189         if (private == NULL) {
1190                 if (options.batch_mode)
1191                         return NULL;
1192                 snprintf(prompt, sizeof prompt,
1193                     "Enter passphrase for key '%.100s': ", filename);
1194                 for (i = 0; i < options.number_of_password_prompts; i++) {
1195                         passphrase = read_passphrase(prompt, 0);
1196                         if (strcmp(passphrase, "") != 0) {
1197                                 private = key_load_private_type(KEY_UNSPEC,
1198                                     filename, passphrase, NULL, NULL);
1199                                 quit = 0;
1200                         } else {
1201                                 debug2("no passphrase given, try next key");
1202                                 quit = 1;
1203                         }
1204                         memset(passphrase, 0, strlen(passphrase));
1205                         xfree(passphrase);
1206                         if (private != NULL || quit)
1207                                 break;
1208                         debug2("bad passphrase given, try again...");
1209                 }
1210         }
1211         return private;
1212 }
1213
1214 /*
1215  * try keys in the following order:
1216  *      1. agent keys that are found in the config file
1217  *      2. other agent keys
1218  *      3. keys that are only listed in the config file
1219  */
1220 static void
1221 pubkey_prepare(Authctxt *authctxt)
1222 {
1223         Identity *id;
1224         Idlist agent, files, *preferred;
1225         Key *key;
1226         AuthenticationConnection *ac;
1227         char *comment;
1228         int i, found;
1229
1230         TAILQ_INIT(&agent);     /* keys from the agent */
1231         TAILQ_INIT(&files);     /* keys from the config file */
1232         preferred = &authctxt->keys;
1233         TAILQ_INIT(preferred);  /* preferred order of keys */
1234
1235         /* list of keys stored in the filesystem */
1236         for (i = 0; i < options.num_identity_files; i++) {
1237                 key = options.identity_keys[i];
1238                 if (key && key->type == KEY_RSA1)
1239                         continue;
1240                 options.identity_keys[i] = NULL;
1241                 id = xcalloc(1, sizeof(*id));
1242                 id->key = key;
1243                 id->filename = xstrdup(options.identity_files[i]);
1244                 TAILQ_INSERT_TAIL(&files, id, next);
1245         }
1246         /* list of keys supported by the agent */
1247         if ((ac = ssh_get_authentication_connection())) {
1248                 for (key = ssh_get_first_identity(ac, &comment, 2);
1249                     key != NULL;
1250                     key = ssh_get_next_identity(ac, &comment, 2)) {
1251                         found = 0;
1252                         TAILQ_FOREACH(id, &files, next) {
1253                                 /* agent keys from the config file are preferred */
1254                                 if (key_equal(key, id->key)) {
1255                                         key_free(key);
1256                                         xfree(comment);
1257                                         TAILQ_REMOVE(&files, id, next);
1258                                         TAILQ_INSERT_TAIL(preferred, id, next);
1259                                         id->ac = ac;
1260                                         found = 1;
1261                                         break;
1262                                 }
1263                         }
1264                         if (!found && !options.identities_only) {
1265                                 id = xcalloc(1, sizeof(*id));
1266                                 id->key = key;
1267                                 id->filename = comment;
1268                                 id->ac = ac;
1269                                 TAILQ_INSERT_TAIL(&agent, id, next);
1270                         }
1271                 }
1272                 /* append remaining agent keys */
1273                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1274                         TAILQ_REMOVE(&agent, id, next);
1275                         TAILQ_INSERT_TAIL(preferred, id, next);
1276                 }
1277                 authctxt->agent = ac;
1278         }
1279         /* append remaining keys from the config file */
1280         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1281                 TAILQ_REMOVE(&files, id, next);
1282                 TAILQ_INSERT_TAIL(preferred, id, next);
1283         }
1284         TAILQ_FOREACH(id, preferred, next) {
1285                 debug2("key: %s (%p)", id->filename, id->key);
1286         }
1287 }
1288
1289 static void
1290 pubkey_cleanup(Authctxt *authctxt)
1291 {
1292         Identity *id;
1293
1294         if (authctxt->agent != NULL)
1295                 ssh_close_authentication_connection(authctxt->agent);
1296         for (id = TAILQ_FIRST(&authctxt->keys); id;
1297             id = TAILQ_FIRST(&authctxt->keys)) {
1298                 TAILQ_REMOVE(&authctxt->keys, id, next);
1299                 if (id->key)
1300                         key_free(id->key);
1301                 if (id->filename)
1302                         xfree(id->filename);
1303                 xfree(id);
1304         }
1305 }
1306
1307 int
1308 userauth_pubkey(Authctxt *authctxt)
1309 {
1310         Identity *id;
1311         int sent = 0;
1312
1313         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1314                 if (id->tried++)
1315                         return (0);
1316                 /* move key to the end of the queue */
1317                 TAILQ_REMOVE(&authctxt->keys, id, next);
1318                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1319                 /*
1320                  * send a test message if we have the public key. for
1321                  * encrypted keys we cannot do this and have to load the
1322                  * private key instead
1323                  */
1324                 if (id->key && id->key->type != KEY_RSA1) {
1325                         debug("Offering public key: %s", id->filename);
1326                         sent = send_pubkey_test(authctxt, id);
1327                 } else if (id->key == NULL) {
1328                         debug("Trying private key: %s", id->filename);
1329                         id->key = load_identity_file(id->filename);
1330                         if (id->key != NULL) {
1331                                 id->isprivate = 1;
1332                                 sent = sign_and_send_pubkey(authctxt, id);
1333                                 key_free(id->key);
1334                                 id->key = NULL;
1335                         }
1336                 }
1337                 if (sent)
1338                         return (sent);
1339         }
1340         return (0);
1341 }
1342
1343 /*
1344  * Send userauth request message specifying keyboard-interactive method.
1345  */
1346 int
1347 userauth_kbdint(Authctxt *authctxt)
1348 {
1349         static int attempt = 0;
1350
1351         if (attempt++ >= options.number_of_password_prompts)
1352                 return 0;
1353         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1354         if (attempt > 1 && !authctxt->info_req_seen) {
1355                 debug3("userauth_kbdint: disable: no info_req_seen");
1356                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1357                 return 0;
1358         }
1359
1360         debug2("userauth_kbdint");
1361         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1362         packet_put_cstring(authctxt->server_user);
1363         packet_put_cstring(authctxt->service);
1364         packet_put_cstring(authctxt->method->name);
1365         packet_put_cstring("");                                 /* lang */
1366         packet_put_cstring(options.kbd_interactive_devices ?
1367             options.kbd_interactive_devices : "");
1368         packet_send();
1369
1370         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1371         return 1;
1372 }
1373
1374 /*
1375  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1376  */
1377 void
1378 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1379 {
1380         Authctxt *authctxt = ctxt;
1381         char *name, *inst, *lang, *prompt, *response;
1382         u_int num_prompts, i;
1383         int echo = 0;
1384
1385         debug2("input_userauth_info_req");
1386
1387         if (authctxt == NULL)
1388                 fatal("input_userauth_info_req: no authentication context");
1389
1390         authctxt->info_req_seen = 1;
1391
1392         name = packet_get_string(NULL);
1393         inst = packet_get_string(NULL);
1394         lang = packet_get_string(NULL);
1395         if (strlen(name) > 0)
1396                 logit("%s", name);
1397         if (strlen(inst) > 0)
1398                 logit("%s", inst);
1399         xfree(name);
1400         xfree(inst);
1401         xfree(lang);
1402
1403         num_prompts = packet_get_int();
1404         /*
1405          * Begin to build info response packet based on prompts requested.
1406          * We commit to providing the correct number of responses, so if
1407          * further on we run into a problem that prevents this, we have to
1408          * be sure and clean this up and send a correct error response.
1409          */
1410         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1411         packet_put_int(num_prompts);
1412
1413         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1414         for (i = 0; i < num_prompts; i++) {
1415                 prompt = packet_get_string(NULL);
1416                 echo = packet_get_char();
1417
1418                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1419
1420                 packet_put_cstring(response);
1421                 memset(response, 0, strlen(response));
1422                 xfree(response);
1423                 xfree(prompt);
1424         }
1425         packet_check_eom(); /* done with parsing incoming message. */
1426
1427         packet_add_padding(64);
1428         packet_send();
1429 }
1430
1431 static int
1432 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1433     u_char *data, u_int datalen)
1434 {
1435         Buffer b;
1436         struct stat st;
1437         pid_t pid;
1438         int to[2], from[2], status, version = 2;
1439
1440         debug2("ssh_keysign called");
1441
1442         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1443                 error("ssh_keysign: no installed: %s", strerror(errno));
1444                 return -1;
1445         }
1446         if (fflush(stdout) != 0)
1447                 error("ssh_keysign: fflush: %s", strerror(errno));
1448         if (pipe(to) < 0) {
1449                 error("ssh_keysign: pipe: %s", strerror(errno));
1450                 return -1;
1451         }
1452         if (pipe(from) < 0) {
1453                 error("ssh_keysign: pipe: %s", strerror(errno));
1454                 return -1;
1455         }
1456         if ((pid = fork()) < 0) {
1457                 error("ssh_keysign: fork: %s", strerror(errno));
1458                 return -1;
1459         }
1460         if (pid == 0) {
1461                 permanently_drop_suid(getuid());
1462                 close(from[0]);
1463                 if (dup2(from[1], STDOUT_FILENO) < 0)
1464                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1465                 close(to[1]);
1466                 if (dup2(to[0], STDIN_FILENO) < 0)
1467                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1468                 close(from[1]);
1469                 close(to[0]);
1470                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1471                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1472                     strerror(errno));
1473         }
1474         close(from[1]);
1475         close(to[0]);
1476
1477         buffer_init(&b);
1478         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1479         buffer_put_string(&b, data, datalen);
1480         if (ssh_msg_send(to[1], version, &b) == -1)
1481                 fatal("ssh_keysign: couldn't send request");
1482
1483         if (ssh_msg_recv(from[0], &b) < 0) {
1484                 error("ssh_keysign: no reply");
1485                 buffer_free(&b);
1486                 return -1;
1487         }
1488         close(from[0]);
1489         close(to[1]);
1490
1491         while (waitpid(pid, &status, 0) < 0)
1492                 if (errno != EINTR)
1493                         break;
1494
1495         if (buffer_get_char(&b) != version) {
1496                 error("ssh_keysign: bad version");
1497                 buffer_free(&b);
1498                 return -1;
1499         }
1500         *sigp = buffer_get_string(&b, lenp);
1501         buffer_free(&b);
1502
1503         return 0;
1504 }
1505
1506 int
1507 userauth_hostbased(Authctxt *authctxt)
1508 {
1509         Key *private = NULL;
1510         Sensitive *sensitive = authctxt->sensitive;
1511         Buffer b;
1512         u_char *signature, *blob;
1513         char *chost, *pkalg, *p;
1514         const char *service;
1515         u_int blen, slen;
1516         int ok, i, len, found = 0;
1517
1518         /* check for a useful key */
1519         for (i = 0; i < sensitive->nkeys; i++) {
1520                 private = sensitive->keys[i];
1521                 if (private && private->type != KEY_RSA1) {
1522                         found = 1;
1523                         /* we take and free the key */
1524                         sensitive->keys[i] = NULL;
1525                         break;
1526                 }
1527         }
1528         if (!found) {
1529                 debug("No more client hostkeys for hostbased authentication.");
1530                 return 0;
1531         }
1532         if (key_to_blob(private, &blob, &blen) == 0) {
1533                 key_free(private);
1534                 return 0;
1535         }
1536         /* figure out a name for the client host */
1537         p = get_local_name(packet_get_connection_in());
1538         if (p == NULL) {
1539                 error("userauth_hostbased: cannot get local ipaddr/name");
1540                 key_free(private);
1541                 xfree(blob);
1542                 return 0;
1543         }
1544         len = strlen(p) + 2;
1545         xasprintf(&chost, "%s.", p);
1546         debug2("userauth_hostbased: chost %s", chost);
1547         xfree(p);
1548
1549         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1550             authctxt->service;
1551         pkalg = xstrdup(key_ssh_name(private));
1552         buffer_init(&b);
1553         /* construct data */
1554         buffer_put_string(&b, session_id2, session_id2_len);
1555         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1556         buffer_put_cstring(&b, authctxt->server_user);
1557         buffer_put_cstring(&b, service);
1558         buffer_put_cstring(&b, authctxt->method->name);
1559         buffer_put_cstring(&b, pkalg);
1560         buffer_put_string(&b, blob, blen);
1561         buffer_put_cstring(&b, chost);
1562         buffer_put_cstring(&b, authctxt->local_user);
1563 #ifdef DEBUG_PK
1564         buffer_dump(&b);
1565 #endif
1566         if (sensitive->external_keysign)
1567                 ok = ssh_keysign(private, &signature, &slen,
1568                     buffer_ptr(&b), buffer_len(&b));
1569         else
1570                 ok = key_sign(private, &signature, &slen,
1571                     buffer_ptr(&b), buffer_len(&b));
1572         key_free(private);
1573         buffer_free(&b);
1574         if (ok != 0) {
1575                 error("key_sign failed");
1576                 xfree(chost);
1577                 xfree(pkalg);
1578                 xfree(blob);
1579                 return 0;
1580         }
1581         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1582         packet_put_cstring(authctxt->server_user);
1583         packet_put_cstring(authctxt->service);
1584         packet_put_cstring(authctxt->method->name);
1585         packet_put_cstring(pkalg);
1586         packet_put_string(blob, blen);
1587         packet_put_cstring(chost);
1588         packet_put_cstring(authctxt->local_user);
1589         packet_put_string(signature, slen);
1590         memset(signature, 's', slen);
1591         xfree(signature);
1592         xfree(chost);
1593         xfree(pkalg);
1594         xfree(blob);
1595
1596         packet_send();
1597         return 1;
1598 }
1599
1600 /* find auth method */
1601
1602 /*
1603  * given auth method name, if configurable options permit this method fill
1604  * in auth_ident field and return true, otherwise return false.
1605  */
1606 static int
1607 authmethod_is_enabled(Authmethod *method)
1608 {
1609         if (method == NULL)
1610                 return 0;
1611         /* return false if options indicate this method is disabled */
1612         if  (method->enabled == NULL || *method->enabled == 0)
1613                 return 0;
1614         /* return false if batch mode is enabled but method needs interactive mode */
1615         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1616                 return 0;
1617         return 1;
1618 }
1619
1620 static Authmethod *
1621 authmethod_lookup(const char *name)
1622 {
1623         Authmethod *method = NULL;
1624         if (name != NULL)
1625                 for (method = authmethods; method->name != NULL; method++)
1626                         if (strcmp(name, method->name) == 0)
1627                                 return method;
1628         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1629         return NULL;
1630 }
1631
1632 /* XXX internal state */
1633 static Authmethod *current = NULL;
1634 static char *supported = NULL;
1635 static char *preferred = NULL;
1636
1637 /*
1638  * Given the authentication method list sent by the server, return the
1639  * next method we should try.  If the server initially sends a nil list,
1640  * use a built-in default list.
1641  */
1642 static Authmethod *
1643 authmethod_get(char *authlist)
1644 {
1645         char *name = NULL;
1646         u_int next;
1647
1648         /* Use a suitable default if we're passed a nil list.  */
1649         if (authlist == NULL || strlen(authlist) == 0)
1650                 authlist = options.preferred_authentications;
1651
1652         if (supported == NULL || strcmp(authlist, supported) != 0) {
1653                 debug3("start over, passed a different list %s", authlist);
1654                 if (supported != NULL)
1655                         xfree(supported);
1656                 supported = xstrdup(authlist);
1657                 preferred = options.preferred_authentications;
1658                 debug3("preferred %s", preferred);
1659                 current = NULL;
1660         } else if (current != NULL && authmethod_is_enabled(current))
1661                 return current;
1662
1663         for (;;) {
1664                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1665                         debug("No more authentication methods to try.");
1666                         current = NULL;
1667                         return NULL;
1668                 }
1669                 preferred += next;
1670                 debug3("authmethod_lookup %s", name);
1671                 debug3("remaining preferred: %s", preferred);
1672                 if ((current = authmethod_lookup(name)) != NULL &&
1673                     authmethod_is_enabled(current)) {
1674                         debug3("authmethod_is_enabled %s", name);
1675                         debug("Next authentication method: %s", name);
1676                         return current;
1677                 }
1678         }
1679 }
1680
1681 static char *
1682 authmethods_get(void)
1683 {
1684         Authmethod *method = NULL;
1685         Buffer b;
1686         char *list;
1687
1688         buffer_init(&b);
1689         for (method = authmethods; method->name != NULL; method++) {
1690                 if (authmethod_is_enabled(method)) {
1691                         if (buffer_len(&b) > 0)
1692                                 buffer_append(&b, ",", 1);
1693                         buffer_append(&b, method->name, strlen(method->name));
1694                 }
1695         }
1696         buffer_append(&b, "\0", 1);
1697         list = xstrdup(buffer_ptr(&b));
1698         buffer_free(&b);
1699         return list;
1700 }