openssh/sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.164 2007/05/17 23:53:41 jolan 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
  42 #include "openbsd-compat/sys-queue.h"
  43
  44 #include "xmalloc.h"
  45 #include "ssh.h"
  46 #include "ssh2.h"
  47 #include "buffer.h"
  48 #include "packet.h"
  49 #include "compat.h"
  50 #include "cipher.h"
  51 #include "key.h"
  52 #include "kex.h"
  53 #include "myproposal.h"
  54 #include "sshconnect.h"
  55 #include "authfile.h"
  56 #include "dh.h"
  57 #include "authfd.h"
  58 #include "log.h"
  59 #include "readconf.h"
  60 #include "misc.h"
  61 #include "match.h"
  62 #include "dispatch.h"
  63 #include "canohost.h"
  64 #include "msg.h"
  65 #include "pathnames.h"
  66 #include "uidswap.h"
  67
  68 #ifdef GSSAPI
  69 #include "ssh-gss.h"
  70 #endif
  71
  72 /* import */
  73 extern char *client_version_string;
  74 extern char *server_version_string;
  75 extern Options options;
  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         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 144             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 145         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 146             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 147         if (options.compression) {
 148                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 149                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 150         } else {
 151                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 152                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 153         }
 154         if (options.macs != NULL) {
 155                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 156                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 157         }
 158         if (options.hostkeyalgorithms != NULL)
 159                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 160                     options.hostkeyalgorithms;
 161
 162 #ifdef GSSAPI
 163         /* If we've got GSSAPI algorithms, then we also support the
 164          * 'null' hostkey, as a last resort */
 165         if (options.gss_keyex && gss) {
 166                 orig = myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
 167                 xasprintf(&myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS],
 168                     "%s,null", orig);
 169         }
 170 #endif
 171
 172         if (options.rekey_limit)
 173                 packet_set_rekey_limit(options.rekey_limit);
 174
 175         /* start key exchange */
 176         kex = kex_setup(myproposal);
 177         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 178         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 179         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 180         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 181 #ifdef GSSAPI
 182         kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client;
 183         kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_client;
 184         kex->kex[KEX_GSS_GEX_SHA1] = kexgss_client;
 185 #endif
 186         kex->client_version_string=client_version_string;
 187         kex->server_version_string=server_version_string;
 188         kex->verify_host_key=&verify_host_key_callback;
 189
 190 #ifdef GSSAPI
 191         kex->gss_deleg_creds = options.gss_deleg_creds;
 192         kex->gss_trust_dns = options.gss_trust_dns;
 193         kex->gss_host = gss_host;
 194 #endif
 195
 196         xxx_kex = kex;
 197
 198         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 199
 200         session_id2 = kex->session_id;
 201         session_id2_len = kex->session_id_len;
 202
 203 #ifdef DEBUG_KEXDH
 204         /* send 1st encrypted/maced/compressed message */
 205         packet_start(SSH2_MSG_IGNORE);
 206         packet_put_cstring("markus");
 207         packet_send();
 208         packet_write_wait();
 209 #endif
 210 }
 211
 212 /*
 213  * Authenticate user
 214  */
 215
 216 typedef struct Authctxt Authctxt;
 217 typedef struct Authmethod Authmethod;
 218 typedef struct identity Identity;
 219 typedef struct idlist Idlist;
 220
 221 struct identity {
 222         TAILQ_ENTRY(identity) next;
 223         AuthenticationConnection *ac;   /* set if agent supports key */
 224         Key     *key;                   /* public/private key */
 225         char    *filename;              /* comment for agent-only keys */
 226         int     tried;
 227         int     isprivate;              /* key points to the private key */
 228 };
 229 TAILQ_HEAD(idlist, identity);
 230
 231 struct Authctxt {
 232         const char *server_user;
 233         const char *local_user;
 234         const char *host;
 235         const char *service;
 236         Authmethod *method;
 237         int success;
 238         char *authlist;
 239         /* pubkey */
 240         Idlist keys;
 241         AuthenticationConnection *agent;
 242         /* hostbased */
 243         Sensitive *sensitive;
 244         /* kbd-interactive */
 245         int info_req_seen;
 246         /* generic */
 247         void *methoddata;
 248 };
 249 struct Authmethod {
 250         char    *name;          /* string to compare against server's list */
 251         int     (*userauth)(Authctxt *authctxt);
 252         int     *enabled;       /* flag in option struct that enables method */
 253         int     *batch_flag;    /* flag in option struct that disables method */
 254 };
 255
 256 void    input_userauth_success(int, u_int32_t, void *);
 257 void    input_userauth_failure(int, u_int32_t, void *);
 258 void    input_userauth_banner(int, u_int32_t, void *);
 259 void    input_userauth_error(int, u_int32_t, void *);
 260 void    input_userauth_info_req(int, u_int32_t, void *);
 261 void    input_userauth_pk_ok(int, u_int32_t, void *);
 262 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 263
 264 int     userauth_none(Authctxt *);
 265 int     userauth_pubkey(Authctxt *);
 266 int     userauth_passwd(Authctxt *);
 267 int     userauth_kbdint(Authctxt *);
 268 int     userauth_hostbased(Authctxt *);
 269 int     userauth_kerberos(Authctxt *);
 270
 271 #ifdef GSSAPI
 272 int     userauth_external(Authctxt *authctxt);
 273 int     userauth_gssapi(Authctxt *authctxt);
 274 int     userauth_gssapi_with_mic(Authctxt *authctxt);
 275 int     userauth_gssapi_without_mic(Authctxt *authctxt);
 276 void    input_gssapi_response(int type, u_int32_t, void *);
 277 void    input_gssapi_token(int type, u_int32_t, void *);
 278 void    input_gssapi_hash(int type, u_int32_t, void *);
 279 void    input_gssapi_error(int, u_int32_t, void *);
 280 void    input_gssapi_errtok(int, u_int32_t, void *);
 281 int     userauth_gsskeyex(Authctxt *authctxt);
 282 #endif
 283
 284 void    userauth(Authctxt *, char *);
 285
 286 static int sign_and_send_pubkey(Authctxt *, Identity *);
 287 static void pubkey_prepare(Authctxt *);
 288 static void pubkey_cleanup(Authctxt *);
 289 static Key *load_identity_file(char *);
 290
 291 static Authmethod *authmethod_get(char *authlist);
 292 static Authmethod *authmethod_lookup(const char *name);
 293 static char *authmethods_get(void);
 294
 295 Authmethod authmethods[] = {
 296 #ifdef GSSAPI
 297         {"gssapi-keyex",
 298                 userauth_gsskeyex,
 299                 &options.gss_authentication,
 300                 NULL},
 301         {"external-keyx",
 302                 userauth_external,
 303                 &options.gss_authentication,
 304                 NULL},
 305         {"gssapi-with-mic",
 306                 userauth_gssapi,
 307                 &options.gss_authentication,
 308                 NULL},
 309         {"gssapi",
 310                 userauth_gssapi,
 311                 &options.gss_authentication,
 312                 NULL},
 313 #endif
 314         {"hostbased",
 315                 userauth_hostbased,
 316                 &options.hostbased_authentication,
 317                 NULL},
 318         {"publickey",
 319                 userauth_pubkey,
 320                 &options.pubkey_authentication,
 321                 NULL},
 322         {"keyboard-interactive",
 323                 userauth_kbdint,
 324                 &options.kbd_interactive_authentication,
 325                 &options.batch_mode},
 326         {"password",
 327                 userauth_passwd,
 328                 &options.password_authentication,
 329                 &options.batch_mode},
 330         {"none",
 331                 userauth_none,
 332                 NULL,
 333                 NULL},
 334         {NULL, NULL, NULL, NULL}
 335 };
 336
 337 void
 338 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 339     Sensitive *sensitive)
 340 {
 341         Authctxt authctxt;
 342         int type;
 343
 344         if (options.challenge_response_authentication)
 345                 options.kbd_interactive_authentication = 1;
 346
 347         packet_start(SSH2_MSG_SERVICE_REQUEST);
 348         packet_put_cstring("ssh-userauth");
 349         packet_send();
 350         debug("SSH2_MSG_SERVICE_REQUEST sent");
 351         packet_write_wait();
 352         type = packet_read();
 353         if (type != SSH2_MSG_SERVICE_ACCEPT)
 354                 fatal("Server denied authentication request: %d", type);
 355         if (packet_remaining() > 0) {
 356                 char *reply = packet_get_string(NULL);
 357                 debug2("service_accept: %s", reply);
 358                 xfree(reply);
 359         } else {
 360                 debug2("buggy server: service_accept w/o service");
 361         }
 362         packet_check_eom();
 363         debug("SSH2_MSG_SERVICE_ACCEPT received");
 364
 365         if (options.preferred_authentications == NULL)
 366                 options.preferred_authentications = authmethods_get();
 367
 368         /* setup authentication context */
 369         memset(&authctxt, 0, sizeof(authctxt));
 370         pubkey_prepare(&authctxt);
 371         authctxt.server_user = server_user;
 372         authctxt.local_user = local_user;
 373         authctxt.host = host;
 374         authctxt.service = "ssh-connection";            /* service name */
 375         authctxt.success = 0;
 376         authctxt.method = authmethod_lookup("none");
 377         authctxt.authlist = NULL;
 378         authctxt.methoddata = NULL;
 379         authctxt.sensitive = sensitive;
 380         authctxt.info_req_seen = 0;
 381         if (authctxt.method == NULL)
 382                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 383
 384         /* initial userauth request */
 385         userauth_none(&authctxt);
 386
 387         dispatch_init(&input_userauth_error);
 388         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 389         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 390         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 391         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 392
 393         pubkey_cleanup(&authctxt);
 394         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 395
 396         /* if the user wants to use the none cipher do it */
 397         /* post authentication and only if the right conditions are met */
 398         /* both of the NONE commands must be true and there must be no */
 399         /* tty allocated */
 400         if ((options.none_switch == 1) && (options.none_enabled == 1))
 401         {
 402                 if (!tty_flag) /* no null on tty sessions */
 403                 {
 404                         debug("Requesting none rekeying...");
 405                         myproposal[PROPOSAL_ENC_ALGS_STOC] = "none";
 406                         myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none";
 407                         kex_prop2buf(&xxx_kex->my,myproposal);
 408                         packet_request_rekeying();
 409                         fprintf(stderr, "WARNING: ENABLED NONE CIPHER\n");
 410                 }
 411                 else
 412                 {
 413                         /* requested NONE cipher when in a tty */
 414                         debug("Cannot switch to NONE cipher with tty allocated");
 415                         fprintf(stderr, "NONE cipher switch disabled when a TTY is allocated\n");
 416                 }
 417         }
 418         debug("Authentication succeeded (%s).", authctxt.method->name);
 419 }
 420
 421 void
 422 userauth(Authctxt *authctxt, char *authlist)
 423 {
 424         if (authctxt->methoddata) {
 425                 xfree(authctxt->methoddata);
 426                 authctxt->methoddata = NULL;
 427         }
 428         if (authlist == NULL) {
 429                 authlist = authctxt->authlist;
 430         } else {
 431                 if (authctxt->authlist)
 432                         xfree(authctxt->authlist);
 433                 authctxt->authlist = authlist;
 434         }
 435         for (;;) {
 436                 Authmethod *method = authmethod_get(authlist);
 437                 if (method == NULL)
 438                         fatal("Permission denied (%s).", authlist);
 439                 authctxt->method = method;
 440
 441                 /* reset the per method handler */
 442                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 443                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 444
 445                 /* and try new method */
 446                 if (method->userauth(authctxt) != 0) {
 447                         debug2("we sent a %s packet, wait for reply", method->name);
 448                         break;
 449                 } else {
 450                         debug2("we did not send a packet, disable method");
 451                         method->enabled = NULL;
 452                 }
 453         }
 454 }
 455
 456 void
 457 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 458 {
 459         fatal("input_userauth_error: bad message during authentication: "
 460             "type %d", type);
 461 }
 462
 463 void
 464 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 465 {
 466         char *msg, *lang;
 467
 468         debug3("input_userauth_banner");
 469         msg = packet_get_string(NULL);
 470         lang = packet_get_string(NULL);
 471         if (options.log_level >= SYSLOG_LEVEL_INFO)
 472                 fprintf(stderr, "%s", msg);
 473         xfree(msg);
 474         xfree(lang);
 475 }
 476
 477 void
 478 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 479 {
 480         Authctxt *authctxt = ctxt;
 481         if (authctxt == NULL)
 482                 fatal("input_userauth_success: no authentication context");
 483         if (authctxt->authlist) {
 484                 xfree(authctxt->authlist);
 485                 authctxt->authlist = NULL;
 486         }
 487         if (authctxt->methoddata) {
 488                 xfree(authctxt->methoddata);
 489                 authctxt->methoddata = NULL;
 490         }
 491         authctxt->success = 1;                  /* break out */
 492 }
 493
 494 void
 495 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 496 {
 497         Authctxt *authctxt = ctxt;
 498         char *authlist = NULL;
 499         int partial;
 500
 501         if (authctxt == NULL)
 502                 fatal("input_userauth_failure: no authentication context");
 503
 504         authlist = packet_get_string(NULL);
 505         partial = packet_get_char();
 506         packet_check_eom();
 507
 508         if (partial != 0)
 509                 logit("Authenticated with partial success.");
 510         debug("Authentications that can continue: %s", authlist);
 511
 512         userauth(authctxt, authlist);
 513 }
 514 void
 515 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 516 {
 517         Authctxt *authctxt = ctxt;
 518         Key *key = NULL;
 519         Identity *id = NULL;
 520         Buffer b;
 521         int pktype, sent = 0;
 522         u_int alen, blen;
 523         char *pkalg, *fp;
 524         u_char *pkblob;
 525
 526         if (authctxt == NULL)
 527                 fatal("input_userauth_pk_ok: no authentication context");
 528         if (datafellows & SSH_BUG_PKOK) {
 529                 /* this is similar to SSH_BUG_PKAUTH */
 530                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 531                 pkblob = packet_get_string(&blen);
 532                 buffer_init(&b);
 533                 buffer_append(&b, pkblob, blen);
 534                 pkalg = buffer_get_string(&b, &alen);
 535                 buffer_free(&b);
 536         } else {
 537                 pkalg = packet_get_string(&alen);
 538                 pkblob = packet_get_string(&blen);
 539         }
 540         packet_check_eom();
 541
 542         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 543
 544         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 545                 debug("unknown pkalg %s", pkalg);
 546                 goto done;
 547         }
 548         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 549                 debug("no key from blob. pkalg %s", pkalg);
 550                 goto done;
 551         }
 552         if (key->type != pktype) {
 553                 error("input_userauth_pk_ok: type mismatch "
 554                     "for decoded key (received %d, expected %d)",
 555                     key->type, pktype);
 556                 goto done;
 557         }
 558         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 559         debug2("input_userauth_pk_ok: fp %s", fp);
 560         xfree(fp);
 561
 562         /*
 563          * search keys in the reverse order, because last candidate has been
 564          * moved to the end of the queue.  this also avoids confusion by
 565          * duplicate keys
 566          */
 567         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 568                 if (key_equal(key, id->key)) {
 569                         sent = sign_and_send_pubkey(authctxt, id);
 570                         break;
 571                 }
 572         }
 573 done:
 574         if (key != NULL)
 575                 key_free(key);
 576         xfree(pkalg);
 577         xfree(pkblob);
 578
 579         /* try another method if we did not send a packet */
 580         if (sent == 0)
 581                 userauth(authctxt, NULL);
 582 }
 583
 584 #ifdef GSSAPI
 585 int
 586 userauth_gssapi(Authctxt *authctxt)
 587 {
 588         Gssctxt *gssctxt = NULL;
 589         static gss_OID_set gss_supported = NULL;
 590         static u_int mech = 0;
 591         OM_uint32 min;
 592         int ok = 0;
 593         char *gss_host = NULL;
 594
 595         if (!options.gss_authentication) {
 596                 verbose("GSSAPI authentication disabled.");
 597                 return 0;
 598         }
 599
 600         if (options.gss_trust_dns)
 601                 gss_host = (char *)get_canonical_hostname(1);
 602         else
 603                 gss_host = (char *)authctxt->host;
 604
 605         /* Try one GSSAPI method at a time, rather than sending them all at
 606          * once. */
 607
 608         if (gss_supported == NULL)
 609                 gss_indicate_mechs(&min, &gss_supported);
 610
 611         /* Check to see if the mechanism is usable before we offer it */
 612         while (mech < gss_supported->count && !ok) {
 613                 /* My DER encoding requires length<128 */
 614                 if (gss_supported->elements[mech].length < 128 &&
 615                     ssh_gssapi_check_mechanism(&gssctxt,
 616                     &gss_supported->elements[mech], gss_host)) {
 617                         ok = 1; /* Mechanism works */
 618                 } else {
 619                         mech++;
 620                 }
 621         }
 622
 623         if (!ok)
 624                 return 0;
 625
 626         authctxt->methoddata=(void *)gssctxt;
 627
 628         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 629         packet_put_cstring(authctxt->server_user);
 630         packet_put_cstring(authctxt->service);
 631         packet_put_cstring(authctxt->method->name);
 632
 633         packet_put_int(1);
 634
 635         packet_put_int((gss_supported->elements[mech].length) + 2);
 636         packet_put_char(SSH_GSS_OIDTYPE);
 637         packet_put_char(gss_supported->elements[mech].length);
 638         packet_put_raw(gss_supported->elements[mech].elements,
 639             gss_supported->elements[mech].length);
 640
 641         packet_send();
 642
 643         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 644         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 645         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 646         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 647
 648         mech++; /* Move along to next candidate */
 649
 650         return 1;
 651 }
 652
 653 static OM_uint32
 654 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 655 {
 656         Authctxt *authctxt = ctxt;
 657         Gssctxt *gssctxt = authctxt->methoddata;
 658         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 659         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 660         gss_buffer_desc gssbuf;
 661         OM_uint32 status, ms, flags;
 662         Buffer b;
 663
 664         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 665             recv_tok, &send_tok, &flags);
 666
 667         if (send_tok.length > 0) {
 668                 if (GSS_ERROR(status))
 669                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 670                 else
 671                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 672
 673                 packet_put_string(send_tok.value, send_tok.length);
 674                 packet_send();
 675                 gss_release_buffer(&ms, &send_tok);
 676         }
 677
 678         if (status == GSS_S_COMPLETE) {
 679                 /* send either complete or MIC, depending on mechanism */
 680                 if (strcmp(authctxt->method->name,"gssapi")==0 ||
 681                     (!(flags & GSS_C_INTEG_FLAG))) {
 682                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 683                         packet_send();
 684                 } else {
 685                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 686                             authctxt->service, "gssapi-with-mic");
 687
 688                         gssbuf.value = buffer_ptr(&b);
 689                         gssbuf.length = buffer_len(&b);
 690
 691                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 692
 693                         if (!GSS_ERROR(status)) {
 694                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 695                                 packet_put_string(mic.value, mic.length);
 696
 697                                 packet_send();
 698                         }
 699
 700                         buffer_free(&b);
 701                         gss_release_buffer(&ms, &mic);
 702                 }
 703         }
 704
 705         return status;
 706 }
 707
 708 void
 709 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 710 {
 711         Authctxt *authctxt = ctxt;
 712         Gssctxt *gssctxt;
 713         u_int oidlen;
 714         u_char *oidv;
 715
 716         if (authctxt == NULL)
 717                 fatal("input_gssapi_response: no authentication context");
 718         gssctxt = authctxt->methoddata;
 719
 720         /* Setup our OID */
 721         oidv = packet_get_string(&oidlen);
 722
 723         if (oidlen <= 2 ||
 724             oidv[0] != SSH_GSS_OIDTYPE ||
 725             oidv[1] != oidlen - 2) {
 726                 xfree(oidv);
 727                 debug("Badly encoded mechanism OID received");
 728                 userauth(authctxt, NULL);
 729                 return;
 730         }
 731
 732         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 733                 fatal("Server returned different OID than expected");
 734
 735         packet_check_eom();
 736
 737         xfree(oidv);
 738
 739         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 740                 /* Start again with next method on list */
 741                 debug("Trying to start again");
 742                 userauth(authctxt, NULL);
 743                 return;
 744         }
 745 }
 746
 747 void
 748 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 749 {
 750         Authctxt *authctxt = ctxt;
 751         gss_buffer_desc recv_tok;
 752         OM_uint32 status;
 753         u_int slen;
 754
 755         if (authctxt == NULL)
 756                 fatal("input_gssapi_response: no authentication context");
 757
 758         recv_tok.value = packet_get_string(&slen);
 759         recv_tok.length = slen; /* safe typecast */
 760
 761         packet_check_eom();
 762
 763         status = process_gssapi_token(ctxt, &recv_tok);
 764
 765         xfree(recv_tok.value);
 766
 767         if (GSS_ERROR(status)) {
 768                 /* Start again with the next method in the list */
 769                 userauth(authctxt, NULL);
 770                 return;
 771         }
 772 }
 773
 774 void
 775 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 776 {
 777         Authctxt *authctxt = ctxt;
 778         Gssctxt *gssctxt;
 779         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 780         gss_buffer_desc recv_tok;
 781         OM_uint32 status, ms;
 782         u_int len;
 783
 784         if (authctxt == NULL)
 785                 fatal("input_gssapi_response: no authentication context");
 786         gssctxt = authctxt->methoddata;
 787
 788         recv_tok.value = packet_get_string(&len);
 789         recv_tok.length = len;
 790
 791         packet_check_eom();
 792
 793         /* Stick it into GSSAPI and see what it says */
 794         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 795             &recv_tok, &send_tok, NULL);
 796
 797         xfree(recv_tok.value);
 798         gss_release_buffer(&ms, &send_tok);
 799
 800         /* Server will be returning a failed packet after this one */
 801 }
 802
 803 void
 804 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 805 {
 806         OM_uint32 maj, min;
 807         char *msg;
 808         char *lang;
 809
 810         maj=packet_get_int();
 811         min=packet_get_int();
 812         msg=packet_get_string(NULL);
 813         lang=packet_get_string(NULL);
 814
 815         packet_check_eom();
 816
 817         debug("Server GSSAPI Error:\n%s", msg);
 818         xfree(msg);
 819         xfree(lang);
 820 }
 821
 822 #ifdef GSI
 823 extern
 824 const gss_OID_desc * const              gss_mech_globus_gssapi_openssl;
 825 #define is_gsi_oid(oid) \
 826   (oid->length == gss_mech_globus_gssapi_openssl->length && \
 827    (memcmp(oid->elements, gss_mech_globus_gssapi_openssl->elements, \
 828            oid->length) == 0))
 829 #endif
 830
 831 int
 832 userauth_external(Authctxt *authctxt)
 833 {
 834         static int attempt = 0;
 835
 836         if (attempt++ >= 1)
 837                 return 0;
 838
 839         /* The client MUST NOT try this method if initial key exchange
 840            was not performed using a GSSAPI-based key exchange
 841            method. */
 842         if (gss_kex_context == NULL) {
 843                 debug2("gsskex not performed, skipping external-keyx");
 844                 return 0;
 845         }
 846
 847         debug2("userauth_external");
 848         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 849 #ifdef GSI
 850         if (options.implicit && is_gsi_oid(gss_kex_context->oid)) {
 851         packet_put_cstring("");
 852         } else {
 853 #endif
 854         packet_put_cstring(authctxt->server_user);
 855 #ifdef GSI
 856         }
 857 #endif
 858         packet_put_cstring(authctxt->service);
 859         packet_put_cstring(authctxt->method->name);
 860         packet_send();
 861         packet_write_wait();
 862         return 1;
 863 }
 864 int
 865 userauth_gsskeyex(Authctxt *authctxt)
 866 {
 867         Buffer b;
 868         gss_buffer_desc gssbuf;
 869         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 870         OM_uint32 ms;
 871
 872         static int attempt = 0;
 873         if (attempt++ >= 1)
 874                 return (0);
 875
 876         if (gss_kex_context == NULL) {
 877                 debug("No valid Key exchange context");
 878                 return (0);
 879         }
 880
 881 #ifdef GSI
 882         if (options.implicit && is_gsi_oid(gss_kex_context->oid)) {
 883         ssh_gssapi_buildmic(&b, "", authctxt->service, "gssapi-keyex");
 884         } else {
 885 #endif
 886         ssh_gssapi_buildmic(&b, authctxt->server_user, authctxt->service,
 887             "gssapi-keyex");
 888 #ifdef GSI
 889         }
 890 #endif
 891
 892         gssbuf.value = buffer_ptr(&b);
 893         gssbuf.length = buffer_len(&b);
 894
 895         if (GSS_ERROR(ssh_gssapi_sign(gss_kex_context, &gssbuf, &mic))) {
 896                 buffer_free(&b);
 897                 return (0);
 898         }
 899
 900         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 901 #ifdef GSI
 902         if (options.implicit && is_gsi_oid(gss_kex_context->oid)) {
 903         packet_put_cstring("");
 904         } else {
 905 #endif
 906         packet_put_cstring(authctxt->server_user);
 907 #ifdef GSI
 908         }
 909 #endif
 910         packet_put_cstring(authctxt->service);
 911         packet_put_cstring(authctxt->method->name);
 912         packet_put_string(mic.value, mic.length);
 913         packet_send();
 914
 915         buffer_free(&b);
 916         gss_release_buffer(&ms, &mic);
 917
 918         return (1);
 919 }
 920
 921 #endif /* GSSAPI */
 922
 923 int
 924 userauth_none(Authctxt *authctxt)
 925 {
 926         /* initial userauth request */
 927         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 928         packet_put_cstring(authctxt->server_user);
 929         packet_put_cstring(authctxt->service);
 930         packet_put_cstring(authctxt->method->name);
 931         packet_send();
 932         return 1;
 933 }
 934
 935 int
 936 userauth_passwd(Authctxt *authctxt)
 937 {
 938         static int attempt = 0;
 939         char prompt[150];
 940         char *password;
 941
 942         if (attempt++ >= options.number_of_password_prompts)
 943                 return 0;
 944
 945         if (attempt != 1)
 946                 error("Permission denied, please try again.");
 947
 948         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 949             authctxt->server_user, authctxt->host);
 950         password = read_passphrase(prompt, 0);
 951         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 952         packet_put_cstring(authctxt->server_user);
 953         packet_put_cstring(authctxt->service);
 954         packet_put_cstring(authctxt->method->name);
 955         packet_put_char(0);
 956         packet_put_cstring(password);
 957         memset(password, 0, strlen(password));
 958         xfree(password);
 959         packet_add_padding(64);
 960         packet_send();
 961
 962         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 963             &input_userauth_passwd_changereq);
 964
 965         return 1;
 966 }
 967 /*
 968  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 969  */
 970 void
 971 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 972 {
 973         Authctxt *authctxt = ctxt;
 974         char *info, *lang, *password = NULL, *retype = NULL;
 975         char prompt[150];
 976
 977         debug2("input_userauth_passwd_changereq");
 978
 979         if (authctxt == NULL)
 980                 fatal("input_userauth_passwd_changereq: "
 981                     "no authentication context");
 982
 983         info = packet_get_string(NULL);
 984         lang = packet_get_string(NULL);
 985         if (strlen(info) > 0)
 986                 logit("%s", info);
 987         xfree(info);
 988         xfree(lang);
 989         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 990         packet_put_cstring(authctxt->server_user);
 991         packet_put_cstring(authctxt->service);
 992         packet_put_cstring(authctxt->method->name);
 993         packet_put_char(1);                     /* additional info */
 994         snprintf(prompt, sizeof(prompt),
 995             "Enter %.30s@%.128s's old password: ",
 996             authctxt->server_user, authctxt->host);
 997         password = read_passphrase(prompt, 0);
 998         packet_put_cstring(password);
 999         memset(password, 0, strlen(password));
1000         xfree(password);
1001         password = NULL;
1002         while (password == NULL) {
1003                 snprintf(prompt, sizeof(prompt),
1004                     "Enter %.30s@%.128s's new password: ",
1005                     authctxt->server_user, authctxt->host);
1006                 password = read_passphrase(prompt, RP_ALLOW_EOF);
1007                 if (password == NULL) {
1008                         /* bail out */
1009                         return;
1010                 }
1011                 snprintf(prompt, sizeof(prompt),
1012                     "Retype %.30s@%.128s's new password: ",
1013                     authctxt->server_user, authctxt->host);
1014                 retype = read_passphrase(prompt, 0);
1015                 if (strcmp(password, retype) != 0) {
1016                         memset(password, 0, strlen(password));
1017                         xfree(password);
1018                         logit("Mismatch; try again, EOF to quit.");
1019                         password = NULL;
1020                 }
1021                 memset(retype, 0, strlen(retype));
1022                 xfree(retype);
1023         }
1024         packet_put_cstring(password);
1025         memset(password, 0, strlen(password));
1026         xfree(password);
1027         packet_add_padding(64);
1028         packet_send();
1029
1030         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
1031             &input_userauth_passwd_changereq);
1032 }
1033
1034 static int
1035 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
1036     u_char *data, u_int datalen)
1037 {
1038         Key *prv;
1039         int ret;
1040
1041         /* the agent supports this key */
1042         if (id->ac)
1043                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1044                     data, datalen));
1045         /*
1046          * we have already loaded the private key or
1047          * the private key is stored in external hardware
1048          */
1049         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1050                 return (key_sign(id->key, sigp, lenp, data, datalen));
1051         /* load the private key from the file */
1052         if ((prv = load_identity_file(id->filename)) == NULL)
1053                 return (-1);
1054         ret = key_sign(prv, sigp, lenp, data, datalen);
1055         key_free(prv);
1056         return (ret);
1057 }
1058
1059 static int
1060 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1061 {
1062         Buffer b;
1063         u_char *blob, *signature;
1064         u_int bloblen, slen;
1065         u_int skip = 0;
1066         int ret = -1;
1067         int have_sig = 1;
1068
1069         debug3("sign_and_send_pubkey");
1070
1071         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1072                 /* we cannot handle this key */
1073                 debug3("sign_and_send_pubkey: cannot handle key");
1074                 return 0;
1075         }
1076         /* data to be signed */
1077         buffer_init(&b);
1078         if (datafellows & SSH_OLD_SESSIONID) {
1079                 buffer_append(&b, session_id2, session_id2_len);
1080                 skip = session_id2_len;
1081         } else {
1082                 buffer_put_string(&b, session_id2, session_id2_len);
1083                 skip = buffer_len(&b);
1084         }
1085         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1086         buffer_put_cstring(&b, authctxt->server_user);
1087         buffer_put_cstring(&b,
1088             datafellows & SSH_BUG_PKSERVICE ?
1089             "ssh-userauth" :
1090             authctxt->service);
1091         if (datafellows & SSH_BUG_PKAUTH) {
1092                 buffer_put_char(&b, have_sig);
1093         } else {
1094                 buffer_put_cstring(&b, authctxt->method->name);
1095                 buffer_put_char(&b, have_sig);
1096                 buffer_put_cstring(&b, key_ssh_name(id->key));
1097         }
1098         buffer_put_string(&b, blob, bloblen);
1099
1100         /* generate signature */
1101         ret = identity_sign(id, &signature, &slen,
1102             buffer_ptr(&b), buffer_len(&b));
1103         if (ret == -1) {
1104                 xfree(blob);
1105                 buffer_free(&b);
1106                 return 0;
1107         }
1108 #ifdef DEBUG_PK
1109         buffer_dump(&b);
1110 #endif
1111         if (datafellows & SSH_BUG_PKSERVICE) {
1112                 buffer_clear(&b);
1113                 buffer_append(&b, session_id2, session_id2_len);
1114                 skip = session_id2_len;
1115                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1116                 buffer_put_cstring(&b, authctxt->server_user);
1117                 buffer_put_cstring(&b, authctxt->service);
1118                 buffer_put_cstring(&b, authctxt->method->name);
1119                 buffer_put_char(&b, have_sig);
1120                 if (!(datafellows & SSH_BUG_PKAUTH))
1121                         buffer_put_cstring(&b, key_ssh_name(id->key));
1122                 buffer_put_string(&b, blob, bloblen);
1123         }
1124         xfree(blob);
1125
1126         /* append signature */
1127         buffer_put_string(&b, signature, slen);
1128         xfree(signature);
1129
1130         /* skip session id and packet type */
1131         if (buffer_len(&b) < skip + 1)
1132                 fatal("userauth_pubkey: internal error");
1133         buffer_consume(&b, skip + 1);
1134
1135         /* put remaining data from buffer into packet */
1136         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1137         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1138         buffer_free(&b);
1139         packet_send();
1140
1141         return 1;
1142 }
1143
1144 static int
1145 send_pubkey_test(Authctxt *authctxt, Identity *id)
1146 {
1147         u_char *blob;
1148         u_int bloblen, have_sig = 0;
1149
1150         debug3("send_pubkey_test");
1151
1152         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1153                 /* we cannot handle this key */
1154                 debug3("send_pubkey_test: cannot handle key");
1155                 return 0;
1156         }
1157         /* register callback for USERAUTH_PK_OK message */
1158         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1159
1160         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1161         packet_put_cstring(authctxt->server_user);
1162         packet_put_cstring(authctxt->service);
1163         packet_put_cstring(authctxt->method->name);
1164         packet_put_char(have_sig);
1165         if (!(datafellows & SSH_BUG_PKAUTH))
1166                 packet_put_cstring(key_ssh_name(id->key));
1167         packet_put_string(blob, bloblen);
1168         xfree(blob);
1169         packet_send();
1170         return 1;
1171 }
1172
1173 static Key *
1174 load_identity_file(char *filename)
1175 {
1176         Key *private;
1177         char prompt[300], *passphrase;
1178         int perm_ok, quit, i;
1179         struct stat st;
1180
1181         if (stat(filename, &st) < 0) {
1182                 debug3("no such identity: %s", filename);
1183                 return NULL;
1184         }
1185         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1186         if (!perm_ok)
1187                 return NULL;
1188         if (private == NULL) {
1189                 if (options.batch_mode)
1190                         return NULL;
1191                 snprintf(prompt, sizeof prompt,
1192                     "Enter passphrase for key '%.100s': ", filename);
1193                 for (i = 0; i < options.number_of_password_prompts; i++) {
1194                         passphrase = read_passphrase(prompt, 0);
1195                         if (strcmp(passphrase, "") != 0) {
1196                                 private = key_load_private_type(KEY_UNSPEC,
1197                                     filename, passphrase, NULL, NULL);
1198                                 quit = 0;
1199                         } else {
1200                                 debug2("no passphrase given, try next key");
1201                                 quit = 1;
1202                         }
1203                         memset(passphrase, 0, strlen(passphrase));
1204                         xfree(passphrase);
1205                         if (private != NULL || quit)
1206                                 break;
1207                         debug2("bad passphrase given, try again...");
1208                 }
1209         }
1210         return private;
1211 }
1212
1213 /*
1214  * try keys in the following order:
1215  *      1. agent keys that are found in the config file
1216  *      2. other agent keys
1217  *      3. keys that are only listed in the config file
1218  */
1219 static void
1220 pubkey_prepare(Authctxt *authctxt)
1221 {
1222         Identity *id;
1223         Idlist agent, files, *preferred;
1224         Key *key;
1225         AuthenticationConnection *ac;
1226         char *comment;
1227         int i, found;
1228
1229         TAILQ_INIT(&agent);     /* keys from the agent */
1230         TAILQ_INIT(&files);     /* keys from the config file */
1231         preferred = &authctxt->keys;
1232         TAILQ_INIT(preferred);  /* preferred order of keys */
1233
1234         /* list of keys stored in the filesystem */
1235         for (i = 0; i < options.num_identity_files; i++) {
1236                 key = options.identity_keys[i];
1237                 if (key && key->type == KEY_RSA1)
1238                         continue;
1239                 options.identity_keys[i] = NULL;
1240                 id = xcalloc(1, sizeof(*id));
1241                 id->key = key;
1242                 id->filename = xstrdup(options.identity_files[i]);
1243                 TAILQ_INSERT_TAIL(&files, id, next);
1244         }
1245         /* list of keys supported by the agent */
1246         if ((ac = ssh_get_authentication_connection())) {
1247                 for (key = ssh_get_first_identity(ac, &comment, 2);
1248                     key != NULL;
1249                     key = ssh_get_next_identity(ac, &comment, 2)) {
1250                         found = 0;
1251                         TAILQ_FOREACH(id, &files, next) {
1252                                 /* agent keys from the config file are preferred */
1253                                 if (key_equal(key, id->key)) {
1254                                         key_free(key);
1255                                         xfree(comment);
1256                                         TAILQ_REMOVE(&files, id, next);
1257                                         TAILQ_INSERT_TAIL(preferred, id, next);
1258                                         id->ac = ac;
1259                                         found = 1;
1260                                         break;
1261                                 }
1262                         }
1263                         if (!found && !options.identities_only) {
1264                                 id = xcalloc(1, sizeof(*id));
1265                                 id->key = key;
1266                                 id->filename = comment;
1267                                 id->ac = ac;
1268                                 TAILQ_INSERT_TAIL(&agent, id, next);
1269                         }
1270                 }
1271                 /* append remaining agent keys */
1272                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1273                         TAILQ_REMOVE(&agent, id, next);
1274                         TAILQ_INSERT_TAIL(preferred, id, next);
1275                 }
1276                 authctxt->agent = ac;
1277         }
1278         /* append remaining keys from the config file */
1279         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1280                 TAILQ_REMOVE(&files, id, next);
1281                 TAILQ_INSERT_TAIL(preferred, id, next);
1282         }
1283         TAILQ_FOREACH(id, preferred, next) {
1284                 debug2("key: %s (%p)", id->filename, id->key);
1285         }
1286 }
1287
1288 static void
1289 pubkey_cleanup(Authctxt *authctxt)
1290 {
1291         Identity *id;
1292
1293         if (authctxt->agent != NULL)
1294                 ssh_close_authentication_connection(authctxt->agent);
1295         for (id = TAILQ_FIRST(&authctxt->keys); id;
1296             id = TAILQ_FIRST(&authctxt->keys)) {
1297                 TAILQ_REMOVE(&authctxt->keys, id, next);
1298                 if (id->key)
1299                         key_free(id->key);
1300                 if (id->filename)
1301                         xfree(id->filename);
1302                 xfree(id);
1303         }
1304 }
1305
1306 int
1307 userauth_pubkey(Authctxt *authctxt)
1308 {
1309         Identity *id;
1310         int sent = 0;
1311
1312         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1313                 if (id->tried++)
1314                         return (0);
1315                 /* move key to the end of the queue */
1316                 TAILQ_REMOVE(&authctxt->keys, id, next);
1317                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1318                 /*
1319                  * send a test message if we have the public key. for
1320                  * encrypted keys we cannot do this and have to load the
1321                  * private key instead
1322                  */
1323                 if (id->key && id->key->type != KEY_RSA1) {
1324                         debug("Offering public key: %s", id->filename);
1325                         sent = send_pubkey_test(authctxt, id);
1326                 } else if (id->key == NULL) {
1327                         debug("Trying private key: %s", id->filename);
1328                         id->key = load_identity_file(id->filename);
1329                         if (id->key != NULL) {
1330                                 id->isprivate = 1;
1331                                 sent = sign_and_send_pubkey(authctxt, id);
1332                                 key_free(id->key);
1333                                 id->key = NULL;
1334                         }
1335                 }
1336                 if (sent)
1337                         return (sent);
1338         }
1339         return (0);
1340 }
1341
1342 /*
1343  * Send userauth request message specifying keyboard-interactive method.
1344  */
1345 int
1346 userauth_kbdint(Authctxt *authctxt)
1347 {
1348         static int attempt = 0;
1349
1350         if (attempt++ >= options.number_of_password_prompts)
1351                 return 0;
1352         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1353         if (attempt > 1 && !authctxt->info_req_seen) {
1354                 debug3("userauth_kbdint: disable: no info_req_seen");
1355                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1356                 return 0;
1357         }
1358
1359         debug2("userauth_kbdint");
1360         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1361         packet_put_cstring(authctxt->server_user);
1362         packet_put_cstring(authctxt->service);
1363         packet_put_cstring(authctxt->method->name);
1364         packet_put_cstring("");                                 /* lang */
1365         packet_put_cstring(options.kbd_interactive_devices ?
1366             options.kbd_interactive_devices : "");
1367         packet_send();
1368
1369         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1370         return 1;
1371 }
1372
1373 /*
1374  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1375  */
1376 void
1377 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1378 {
1379         Authctxt *authctxt = ctxt;
1380         char *name, *inst, *lang, *prompt, *response;
1381         u_int num_prompts, i;
1382         int echo = 0;
1383
1384         debug2("input_userauth_info_req");
1385
1386         if (authctxt == NULL)
1387                 fatal("input_userauth_info_req: no authentication context");
1388
1389         authctxt->info_req_seen = 1;
1390
1391         name = packet_get_string(NULL);
1392         inst = packet_get_string(NULL);
1393         lang = packet_get_string(NULL);
1394         if (strlen(name) > 0)
1395                 logit("%s", name);
1396         if (strlen(inst) > 0)
1397                 logit("%s", inst);
1398         xfree(name);
1399         xfree(inst);
1400         xfree(lang);
1401
1402         num_prompts = packet_get_int();
1403         /*
1404          * Begin to build info response packet based on prompts requested.
1405          * We commit to providing the correct number of responses, so if
1406          * further on we run into a problem that prevents this, we have to
1407          * be sure and clean this up and send a correct error response.
1408          */
1409         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1410         packet_put_int(num_prompts);
1411
1412         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1413         for (i = 0; i < num_prompts; i++) {
1414                 prompt = packet_get_string(NULL);
1415                 echo = packet_get_char();
1416
1417                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1418
1419                 packet_put_cstring(response);
1420                 memset(response, 0, strlen(response));
1421                 xfree(response);
1422                 xfree(prompt);
1423         }
1424         packet_check_eom(); /* done with parsing incoming message. */
1425
1426         packet_add_padding(64);
1427         packet_send();
1428 }
1429
1430 static int
1431 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1432     u_char *data, u_int datalen)
1433 {
1434         Buffer b;
1435         struct stat st;
1436         pid_t pid;
1437         int to[2], from[2], status, version = 2;
1438
1439         debug2("ssh_keysign called");
1440
1441         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1442                 error("ssh_keysign: no installed: %s", strerror(errno));
1443                 return -1;
1444         }
1445         if (fflush(stdout) != 0)
1446                 error("ssh_keysign: fflush: %s", strerror(errno));
1447         if (pipe(to) < 0) {
1448                 error("ssh_keysign: pipe: %s", strerror(errno));
1449                 return -1;
1450         }
1451         if (pipe(from) < 0) {
1452                 error("ssh_keysign: pipe: %s", strerror(errno));
1453                 return -1;
1454         }
1455         if ((pid = fork()) < 0) {
1456                 error("ssh_keysign: fork: %s", strerror(errno));
1457                 return -1;
1458         }
1459         if (pid == 0) {
1460                 permanently_drop_suid(getuid());
1461                 close(from[0]);
1462                 if (dup2(from[1], STDOUT_FILENO) < 0)
1463                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1464                 close(to[1]);
1465                 if (dup2(to[0], STDIN_FILENO) < 0)
1466                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1467                 close(from[1]);
1468                 close(to[0]);
1469                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1470                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1471                     strerror(errno));
1472         }
1473         close(from[1]);
1474         close(to[0]);
1475
1476         buffer_init(&b);
1477         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1478         buffer_put_string(&b, data, datalen);
1479         if (ssh_msg_send(to[1], version, &b) == -1)
1480                 fatal("ssh_keysign: couldn't send request");
1481
1482         if (ssh_msg_recv(from[0], &b) < 0) {
1483                 error("ssh_keysign: no reply");
1484                 buffer_free(&b);
1485                 return -1;
1486         }
1487         close(from[0]);
1488         close(to[1]);
1489
1490         while (waitpid(pid, &status, 0) < 0)
1491                 if (errno != EINTR)
1492                         break;
1493
1494         if (buffer_get_char(&b) != version) {
1495                 error("ssh_keysign: bad version");
1496                 buffer_free(&b);
1497                 return -1;
1498         }
1499         *sigp = buffer_get_string(&b, lenp);
1500         buffer_free(&b);
1501
1502         return 0;
1503 }
1504
1505 int
1506 userauth_hostbased(Authctxt *authctxt)
1507 {
1508         Key *private = NULL;
1509         Sensitive *sensitive = authctxt->sensitive;
1510         Buffer b;
1511         u_char *signature, *blob;
1512         char *chost, *pkalg, *p, myname[NI_MAXHOST];
1513         const char *service;
1514         u_int blen, slen;
1515         int ok, i, len, found = 0;
1516
1517         /* check for a useful key */
1518         for (i = 0; i < sensitive->nkeys; i++) {
1519                 private = sensitive->keys[i];
1520                 if (private && private->type != KEY_RSA1) {
1521                         found = 1;
1522                         /* we take and free the key */
1523                         sensitive->keys[i] = NULL;
1524                         break;
1525                 }
1526         }
1527         if (!found) {
1528                 debug("No more client hostkeys for hostbased authentication.");
1529                 return 0;
1530         }
1531         if (key_to_blob(private, &blob, &blen) == 0) {
1532                 key_free(private);
1533                 return 0;
1534         }
1535         /* figure out a name for the client host */
1536         p = NULL;
1537         if (packet_connection_is_on_socket())
1538                 p = get_local_name(packet_get_connection_in());
1539         if (p == NULL) {
1540                 if (gethostname(myname, sizeof(myname)) == -1) {
1541                         verbose("userauth_hostbased: gethostname: %s",
1542                             strerror(errno));
1543                 } else
1544                         p = xstrdup(myname);
1545         }
1546         if (p == NULL) {
1547                 error("userauth_hostbased: cannot get local ipaddr/name");
1548                 key_free(private);
1549                 xfree(blob);
1550                 return 0;
1551         }
1552         len = strlen(p) + 2;
1553         xasprintf(&chost, "%s.", p);
1554         debug2("userauth_hostbased: chost %s", chost);
1555         xfree(p);
1556
1557         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1558             authctxt->service;
1559         pkalg = xstrdup(key_ssh_name(private));
1560         buffer_init(&b);
1561         /* construct data */
1562         buffer_put_string(&b, session_id2, session_id2_len);
1563         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1564         buffer_put_cstring(&b, authctxt->server_user);
1565         buffer_put_cstring(&b, service);
1566         buffer_put_cstring(&b, authctxt->method->name);
1567         buffer_put_cstring(&b, pkalg);
1568         buffer_put_string(&b, blob, blen);
1569         buffer_put_cstring(&b, chost);
1570         buffer_put_cstring(&b, authctxt->local_user);
1571 #ifdef DEBUG_PK
1572         buffer_dump(&b);
1573 #endif
1574         if (sensitive->external_keysign)
1575                 ok = ssh_keysign(private, &signature, &slen,
1576                     buffer_ptr(&b), buffer_len(&b));
1577         else
1578                 ok = key_sign(private, &signature, &slen,
1579                     buffer_ptr(&b), buffer_len(&b));
1580         key_free(private);
1581         buffer_free(&b);
1582         if (ok != 0) {
1583                 error("key_sign failed");
1584                 xfree(chost);
1585                 xfree(pkalg);
1586                 xfree(blob);
1587                 return 0;
1588         }
1589         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1590         packet_put_cstring(authctxt->server_user);
1591         packet_put_cstring(authctxt->service);
1592         packet_put_cstring(authctxt->method->name);
1593         packet_put_cstring(pkalg);
1594         packet_put_string(blob, blen);
1595         packet_put_cstring(chost);
1596         packet_put_cstring(authctxt->local_user);
1597         packet_put_string(signature, slen);
1598         memset(signature, 's', slen);
1599         xfree(signature);
1600         xfree(chost);
1601         xfree(pkalg);
1602         xfree(blob);
1603
1604         packet_send();
1605         return 1;
1606 }
1607
1608 /* find auth method */
1609
1610 /*
1611  * given auth method name, if configurable options permit this method fill
1612  * in auth_ident field and return true, otherwise return false.
1613  */
1614 static int
1615 authmethod_is_enabled(Authmethod *method)
1616 {
1617         if (method == NULL)
1618                 return 0;
1619         /* return false if options indicate this method is disabled */
1620         if  (method->enabled == NULL || *method->enabled == 0)
1621                 return 0;
1622         /* return false if batch mode is enabled but method needs interactive mode */
1623         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1624                 return 0;
1625         return 1;
1626 }
1627
1628 static Authmethod *
1629 authmethod_lookup(const char *name)
1630 {
1631         Authmethod *method = NULL;
1632         if (name != NULL)
1633                 for (method = authmethods; method->name != NULL; method++)
1634                         if (strcmp(name, method->name) == 0)
1635                                 return method;
1636         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1637         return NULL;
1638 }
1639
1640 /* XXX internal state */
1641 static Authmethod *current = NULL;
1642 static char *supported = NULL;
1643 static char *preferred = NULL;
1644
1645 /*
1646  * Given the authentication method list sent by the server, return the
1647  * next method we should try.  If the server initially sends a nil list,
1648  * use a built-in default list.
1649  */
1650 static Authmethod *
1651 authmethod_get(char *authlist)
1652 {
1653         char *name = NULL;
1654         u_int next;
1655
1656         /* Use a suitable default if we're passed a nil list.  */
1657         if (authlist == NULL || strlen(authlist) == 0)
1658                 authlist = options.preferred_authentications;
1659
1660         if (supported == NULL || strcmp(authlist, supported) != 0) {
1661                 debug3("start over, passed a different list %s", authlist);
1662                 if (supported != NULL)
1663                         xfree(supported);
1664                 supported = xstrdup(authlist);
1665                 preferred = options.preferred_authentications;
1666                 debug3("preferred %s", preferred);
1667                 current = NULL;
1668         } else if (current != NULL && authmethod_is_enabled(current))
1669                 return current;
1670
1671         for (;;) {
1672                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1673                         debug("No more authentication methods to try.");
1674                         current = NULL;
1675                         return NULL;
1676                 }
1677                 preferred += next;
1678                 debug3("authmethod_lookup %s", name);
1679                 debug3("remaining preferred: %s", preferred);
1680                 if ((current = authmethod_lookup(name)) != NULL &&
1681                     authmethod_is_enabled(current)) {
1682                         debug3("authmethod_is_enabled %s", name);
1683                         debug("Next authentication method: %s", name);
1684                         return current;
1685                 }
1686         }
1687 }
1688
1689 static char *
1690 authmethods_get(void)
1691 {
1692         Authmethod *method = NULL;
1693         Buffer b;
1694         char *list;
1695
1696         buffer_init(&b);
1697         for (method = authmethods; method->name != NULL; method++) {
1698                 if (authmethod_is_enabled(method)) {
1699                         if (buffer_len(&b) > 0)
1700                                 buffer_append(&b, ",", 1);
1701                         buffer_append(&b, method->name, strlen(method->name));
1702                 }
1703         }
1704         buffer_append(&b, "\0", 1);
1705         list = xstrdup(buffer_ptr(&b));
1706         buffer_free(&b);
1707         return list;
1708 }