openssh/sshconnect2.c

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