openssh/sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.162 2006/08/30 00:06:51 dtucker Exp $ */
   2 /*
   3  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "includes.h"
  27
  28 #include <sys/types.h>
  29 #include <sys/socket.h>
  30 #include <sys/wait.h>
  31 #include <sys/stat.h>
  32
  33 #include <errno.h>
  34 #include <pwd.h>
  35 #include <signal.h>
  36 #include <stdarg.h>
  37 #include <stdio.h>
  38 #include <string.h>
  39 #include <unistd.h>
  40
  41 #include "openbsd-compat/sys-queue.h"
  42
  43 #include "xmalloc.h"
  44 #include "ssh.h"
  45 #include "ssh2.h"
  46 #include "buffer.h"
  47 #include "packet.h"
  48 #include "compat.h"
  49 #include "cipher.h"
  50 #include "key.h"
  51 #include "kex.h"
  52 #include "myproposal.h"
  53 #include "sshconnect.h"
  54 #include "authfile.h"
  55 #include "dh.h"
  56 #include "authfd.h"
  57 #include "log.h"
  58 #include "readconf.h"
  59 #include "misc.h"
  60 #include "match.h"
  61 #include "dispatch.h"
  62 #include "canohost.h"
  63 #include "msg.h"
  64 #include "pathnames.h"
  65 #include "uidswap.h"
  66
  67 #ifdef GSSAPI
  68 #include "ssh-gss.h"
  69 #endif
  70
  71 /* import */
  72 extern char *client_version_string;
  73 extern char *server_version_string;
  74 extern Options options;
  75
  76 /*
  77  * SSH2 key exchange
  78  */
  79
  80 u_char *session_id2 = NULL;
  81 u_int session_id2_len = 0;
  82
  83 char *xxx_host;
  84 struct sockaddr *xxx_hostaddr;
  85
  86 Kex *xxx_kex = NULL;
  87
  88 static int
  89 verify_host_key_callback(Key *hostkey)
  90 {
  91         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
  92                 fatal("Host key verification failed.");
  93         return 0;
  94 }
  95
  96 void
  97 ssh_kex2(char *host, struct sockaddr *hostaddr)
  98 {
  99         Kex *kex;
 100
 101 #ifdef GSSAPI
 102         char *orig = NULL, *gss = NULL;
 103         char *gss_host = NULL;
 104 #endif
 105
 106         xxx_host = host;
 107         xxx_hostaddr = hostaddr;
 108
 109 #ifdef GSSAPI
 110         if (options.gss_keyex) {
 111                 /* Add the GSSAPI mechanisms currently supported on this
 112                  * client to the key exchange algorithm proposal */
 113                 orig = myproposal[PROPOSAL_KEX_ALGS];
 114
 115                 if (options.gss_trust_dns)
 116                         gss_host = (char *)get_canonical_hostname(1);
 117                 else
 118                         gss_host = host;
 119
 120                 gss = ssh_gssapi_client_mechanisms(gss_host);
 121                 if (gss) {
 122                         debug("Offering GSSAPI proposal: %s", gss);
 123                         xasprintf(&myproposal[PROPOSAL_KEX_ALGS],
 124                             "%s,%s", gss, orig);
 125                 }
 126         }
 127 #endif
 128
 129         if (options.ciphers == (char *)-1) {
 130                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 131                 options.ciphers = NULL;
 132         }
 133         if (options.ciphers != NULL) {
 134                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 135                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 136         }
 137         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 138             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 139         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 140             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 141         if (options.compression) {
 142                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 143                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 144         } else {
 145                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 146                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 147         }
 148         if (options.macs != NULL) {
 149                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 150                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 151         }
 152         if (options.hostkeyalgorithms != NULL)
 153                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 154                     options.hostkeyalgorithms;
 155
 156 #ifdef GSSAPI
 157         /* If we've got GSSAPI algorithms, then we also support the
 158          * 'null' hostkey, as a last resort */
 159         if (options.gss_keyex && gss) {
 160                 orig = myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
 161                 xasprintf(&myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS],
 162                     "%s,null", orig);
 163         }
 164 #endif
 165
 166         if (options.rekey_limit)
 167                 packet_set_rekey_limit(options.rekey_limit);
 168
 169         /* start key exchange */
 170         kex = kex_setup(myproposal);
 171         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 172         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 173         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 174         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 175 #ifdef GSSAPI
 176         kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client;
 177         kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_client;
 178         kex->kex[KEX_GSS_GEX_SHA1] = kexgss_client;
 179 #endif
 180         kex->client_version_string=client_version_string;
 181         kex->server_version_string=server_version_string;
 182         kex->verify_host_key=&verify_host_key_callback;
 183
 184 #ifdef GSSAPI
 185         kex->gss_deleg_creds = options.gss_deleg_creds;
 186         kex->gss_trust_dns = options.gss_trust_dns;
 187         kex->gss_host = gss_host;
 188 #endif
 189
 190         xxx_kex = kex;
 191
 192         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 193
 194         session_id2 = kex->session_id;
 195         session_id2_len = kex->session_id_len;
 196
 197 #ifdef DEBUG_KEXDH
 198         /* send 1st encrypted/maced/compressed message */
 199         packet_start(SSH2_MSG_IGNORE);
 200         packet_put_cstring("markus");
 201         packet_send();
 202         packet_write_wait();
 203 #endif
 204 }
 205
 206 /*
 207  * Authenticate user
 208  */
 209
 210 typedef struct Authctxt Authctxt;
 211 typedef struct Authmethod Authmethod;
 212 typedef struct identity Identity;
 213 typedef struct idlist Idlist;
 214
 215 struct identity {
 216         TAILQ_ENTRY(identity) next;
 217         AuthenticationConnection *ac;   /* set if agent supports key */
 218         Key     *key;                   /* public/private key */
 219         char    *filename;              /* comment for agent-only keys */
 220         int     tried;
 221         int     isprivate;              /* key points to the private key */
 222 };
 223 TAILQ_HEAD(idlist, identity);
 224
 225 struct Authctxt {
 226         const char *server_user;
 227         const char *local_user;
 228         const char *host;
 229         const char *service;
 230         Authmethod *method;
 231         int success;
 232         char *authlist;
 233         /* pubkey */
 234         Idlist keys;
 235         AuthenticationConnection *agent;
 236         /* hostbased */
 237         Sensitive *sensitive;
 238         /* kbd-interactive */
 239         int info_req_seen;
 240         /* generic */
 241         void *methoddata;
 242 };
 243 struct Authmethod {
 244         char    *name;          /* string to compare against server's list */
 245         int     (*userauth)(Authctxt *authctxt);
 246         int     *enabled;       /* flag in option struct that enables method */
 247         int     *batch_flag;    /* flag in option struct that disables method */
 248 };
 249
 250 void    input_userauth_success(int, u_int32_t, void *);
 251 void    input_userauth_failure(int, u_int32_t, void *);
 252 void    input_userauth_banner(int, u_int32_t, void *);
 253 void    input_userauth_error(int, u_int32_t, void *);
 254 void    input_userauth_info_req(int, u_int32_t, void *);
 255 void    input_userauth_pk_ok(int, u_int32_t, void *);
 256 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 257
 258 int     userauth_none(Authctxt *);
 259 int     userauth_pubkey(Authctxt *);
 260 int     userauth_passwd(Authctxt *);
 261 int     userauth_kbdint(Authctxt *);
 262 int     userauth_hostbased(Authctxt *);
 263 int     userauth_kerberos(Authctxt *);
 264
 265 #ifdef GSSAPI
 266 int     userauth_gssapi(Authctxt *authctxt);
 267 void    input_gssapi_response(int type, u_int32_t, void *);
 268 void    input_gssapi_token(int type, u_int32_t, void *);
 269 void    input_gssapi_hash(int type, u_int32_t, void *);
 270 void    input_gssapi_error(int, u_int32_t, void *);
 271 void    input_gssapi_errtok(int, u_int32_t, void *);
 272 int     userauth_gsskeyex(Authctxt *authctxt);
 273 #endif
 274
 275 void    userauth(Authctxt *, char *);
 276
 277 static int sign_and_send_pubkey(Authctxt *, Identity *);
 278 static void pubkey_prepare(Authctxt *);
 279 static void pubkey_cleanup(Authctxt *);
 280 static Key *load_identity_file(char *);
 281
 282 static Authmethod *authmethod_get(char *authlist);
 283 static Authmethod *authmethod_lookup(const char *name);
 284 static char *authmethods_get(void);
 285
 286 Authmethod authmethods[] = {
 287 #ifdef GSSAPI
 288         {"gssapi-keyex",
 289                 userauth_gsskeyex,
 290                 &options.gss_authentication,
 291                 NULL},
 292         {"gssapi-with-mic",
 293                 userauth_gssapi,
 294                 &options.gss_authentication,
 295                 NULL},
 296 #endif
 297         {"hostbased",
 298                 userauth_hostbased,
 299                 &options.hostbased_authentication,
 300                 NULL},
 301         {"publickey",
 302                 userauth_pubkey,
 303                 &options.pubkey_authentication,
 304                 NULL},
 305         {"keyboard-interactive",
 306                 userauth_kbdint,
 307                 &options.kbd_interactive_authentication,
 308                 &options.batch_mode},
 309         {"password",
 310                 userauth_passwd,
 311                 &options.password_authentication,
 312                 &options.batch_mode},
 313         {"none",
 314                 userauth_none,
 315                 NULL,
 316                 NULL},
 317         {NULL, NULL, NULL, NULL}
 318 };
 319
 320 void
 321 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 322     Sensitive *sensitive)
 323 {
 324         Authctxt authctxt;
 325         int type;
 326
 327         if (options.challenge_response_authentication)
 328                 options.kbd_interactive_authentication = 1;
 329
 330         packet_start(SSH2_MSG_SERVICE_REQUEST);
 331         packet_put_cstring("ssh-userauth");
 332         packet_send();
 333         debug("SSH2_MSG_SERVICE_REQUEST sent");
 334         packet_write_wait();
 335         type = packet_read();
 336         if (type != SSH2_MSG_SERVICE_ACCEPT)
 337                 fatal("Server denied authentication request: %d", type);
 338         if (packet_remaining() > 0) {
 339                 char *reply = packet_get_string(NULL);
 340                 debug2("service_accept: %s", reply);
 341                 xfree(reply);
 342         } else {
 343                 debug2("buggy server: service_accept w/o service");
 344         }
 345         packet_check_eom();
 346         debug("SSH2_MSG_SERVICE_ACCEPT received");
 347
 348         if (options.preferred_authentications == NULL)
 349                 options.preferred_authentications = authmethods_get();
 350
 351         /* setup authentication context */
 352         memset(&authctxt, 0, sizeof(authctxt));
 353         pubkey_prepare(&authctxt);
 354         authctxt.server_user = server_user;
 355         authctxt.local_user = local_user;
 356         authctxt.host = host;
 357         authctxt.service = "ssh-connection";            /* service name */
 358         authctxt.success = 0;
 359         authctxt.method = authmethod_lookup("none");
 360         authctxt.authlist = NULL;
 361         authctxt.methoddata = NULL;
 362         authctxt.sensitive = sensitive;
 363         authctxt.info_req_seen = 0;
 364         if (authctxt.method == NULL)
 365                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 366
 367         /* initial userauth request */
 368         userauth_none(&authctxt);
 369
 370         dispatch_init(&input_userauth_error);
 371         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 372         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 373         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 374         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 375
 376         pubkey_cleanup(&authctxt);
 377         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 378
 379         debug("Authentication succeeded (%s).", authctxt.method->name);
 380 }
 381
 382 void
 383 userauth(Authctxt *authctxt, char *authlist)
 384 {
 385         if (authctxt->methoddata) {
 386                 xfree(authctxt->methoddata);
 387                 authctxt->methoddata = NULL;
 388         }
 389         if (authlist == NULL) {
 390                 authlist = authctxt->authlist;
 391         } else {
 392                 if (authctxt->authlist)
 393                         xfree(authctxt->authlist);
 394                 authctxt->authlist = authlist;
 395         }
 396         for (;;) {
 397                 Authmethod *method = authmethod_get(authlist);
 398                 if (method == NULL)
 399                         fatal("Permission denied (%s).", authlist);
 400                 authctxt->method = method;
 401
 402                 /* reset the per method handler */
 403                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 404                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 405
 406                 /* and try new method */
 407                 if (method->userauth(authctxt) != 0) {
 408                         debug2("we sent a %s packet, wait for reply", method->name);
 409                         break;
 410                 } else {
 411                         debug2("we did not send a packet, disable method");
 412                         method->enabled = NULL;
 413                 }
 414         }
 415 }
 416
 417 void
 418 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 419 {
 420         fatal("input_userauth_error: bad message during authentication: "
 421             "type %d", type);
 422 }
 423
 424 void
 425 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 426 {
 427         char *msg, *lang;
 428
 429         debug3("input_userauth_banner");
 430         msg = packet_get_string(NULL);
 431         lang = packet_get_string(NULL);
 432         if (options.log_level >= SYSLOG_LEVEL_INFO)
 433                 fprintf(stderr, "%s", msg);
 434         xfree(msg);
 435         xfree(lang);
 436 }
 437
 438 void
 439 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 440 {
 441         Authctxt *authctxt = ctxt;
 442         if (authctxt == NULL)
 443                 fatal("input_userauth_success: no authentication context");
 444         if (authctxt->authlist) {
 445                 xfree(authctxt->authlist);
 446                 authctxt->authlist = NULL;
 447         }
 448         if (authctxt->methoddata) {
 449                 xfree(authctxt->methoddata);
 450                 authctxt->methoddata = NULL;
 451         }
 452         authctxt->success = 1;                  /* break out */
 453 }
 454
 455 void
 456 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 457 {
 458         Authctxt *authctxt = ctxt;
 459         char *authlist = NULL;
 460         int partial;
 461
 462         if (authctxt == NULL)
 463                 fatal("input_userauth_failure: no authentication context");
 464
 465         authlist = packet_get_string(NULL);
 466         partial = packet_get_char();
 467         packet_check_eom();
 468
 469         if (partial != 0)
 470                 logit("Authenticated with partial success.");
 471         debug("Authentications that can continue: %s", authlist);
 472
 473         userauth(authctxt, authlist);
 474 }
 475 void
 476 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 477 {
 478         Authctxt *authctxt = ctxt;
 479         Key *key = NULL;
 480         Identity *id = NULL;
 481         Buffer b;
 482         int pktype, sent = 0;
 483         u_int alen, blen;
 484         char *pkalg, *fp;
 485         u_char *pkblob;
 486
 487         if (authctxt == NULL)
 488                 fatal("input_userauth_pk_ok: no authentication context");
 489         if (datafellows & SSH_BUG_PKOK) {
 490                 /* this is similar to SSH_BUG_PKAUTH */
 491                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 492                 pkblob = packet_get_string(&blen);
 493                 buffer_init(&b);
 494                 buffer_append(&b, pkblob, blen);
 495                 pkalg = buffer_get_string(&b, &alen);
 496                 buffer_free(&b);
 497         } else {
 498                 pkalg = packet_get_string(&alen);
 499                 pkblob = packet_get_string(&blen);
 500         }
 501         packet_check_eom();
 502
 503         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 504
 505         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 506                 debug("unknown pkalg %s", pkalg);
 507                 goto done;
 508         }
 509         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 510                 debug("no key from blob. pkalg %s", pkalg);
 511                 goto done;
 512         }
 513         if (key->type != pktype) {
 514                 error("input_userauth_pk_ok: type mismatch "
 515                     "for decoded key (received %d, expected %d)",
 516                     key->type, pktype);
 517                 goto done;
 518         }
 519         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 520         debug2("input_userauth_pk_ok: fp %s", fp);
 521         xfree(fp);
 522
 523         /*
 524          * search keys in the reverse order, because last candidate has been
 525          * moved to the end of the queue.  this also avoids confusion by
 526          * duplicate keys
 527          */
 528         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 529                 if (key_equal(key, id->key)) {
 530                         sent = sign_and_send_pubkey(authctxt, id);
 531                         break;
 532                 }
 533         }
 534 done:
 535         if (key != NULL)
 536                 key_free(key);
 537         xfree(pkalg);
 538         xfree(pkblob);
 539
 540         /* try another method if we did not send a packet */
 541         if (sent == 0)
 542                 userauth(authctxt, NULL);
 543 }
 544
 545 #ifdef GSSAPI
 546 int
 547 userauth_gssapi(Authctxt *authctxt)
 548 {
 549         Gssctxt *gssctxt = NULL;
 550         static gss_OID_set gss_supported = NULL;
 551         static u_int mech = 0;
 552         OM_uint32 min;
 553         int ok = 0;
 554         char *gss_host = NULL;
 555
 556         if (options.gss_trust_dns)
 557                 gss_host = (char *)get_canonical_hostname(1);
 558         else
 559                 gss_host = (char *)authctxt->host;
 560
 561         /* Try one GSSAPI method at a time, rather than sending them all at
 562          * once. */
 563
 564         if (gss_supported == NULL)
 565                 gss_indicate_mechs(&min, &gss_supported);
 566
 567         /* Check to see if the mechanism is usable before we offer it */
 568         while (mech < gss_supported->count && !ok) {
 569                 /* My DER encoding requires length<128 */
 570                 if (gss_supported->elements[mech].length < 128 &&
 571                     ssh_gssapi_check_mechanism(&gssctxt,
 572                     &gss_supported->elements[mech], gss_host)) {
 573                         ok = 1; /* Mechanism works */
 574                 } else {
 575                         mech++;
 576                 }
 577         }
 578
 579         if (!ok)
 580                 return 0;
 581
 582         authctxt->methoddata=(void *)gssctxt;
 583
 584         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 585         packet_put_cstring(authctxt->server_user);
 586         packet_put_cstring(authctxt->service);
 587         packet_put_cstring(authctxt->method->name);
 588
 589         packet_put_int(1);
 590
 591         packet_put_int((gss_supported->elements[mech].length) + 2);
 592         packet_put_char(SSH_GSS_OIDTYPE);
 593         packet_put_char(gss_supported->elements[mech].length);
 594         packet_put_raw(gss_supported->elements[mech].elements,
 595             gss_supported->elements[mech].length);
 596
 597         packet_send();
 598
 599         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 600         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 601         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 602         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 603
 604         mech++; /* Move along to next candidate */
 605
 606         return 1;
 607 }
 608
 609 static OM_uint32
 610 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 611 {
 612         Authctxt *authctxt = ctxt;
 613         Gssctxt *gssctxt = authctxt->methoddata;
 614         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 615         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 616         gss_buffer_desc gssbuf;
 617         OM_uint32 status, ms, flags;
 618         Buffer b;
 619
 620         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 621             recv_tok, &send_tok, &flags);
 622
 623         if (send_tok.length > 0) {
 624                 if (GSS_ERROR(status))
 625                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 626                 else
 627                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 628
 629                 packet_put_string(send_tok.value, send_tok.length);
 630                 packet_send();
 631                 gss_release_buffer(&ms, &send_tok);
 632         }
 633
 634         if (status == GSS_S_COMPLETE) {
 635                 /* send either complete or MIC, depending on mechanism */
 636                 if (!(flags & GSS_C_INTEG_FLAG)) {
 637                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 638                         packet_send();
 639                 } else {
 640                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 641                             authctxt->service, "gssapi-with-mic");
 642
 643                         gssbuf.value = buffer_ptr(&b);
 644                         gssbuf.length = buffer_len(&b);
 645
 646                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 647
 648                         if (!GSS_ERROR(status)) {
 649                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 650                                 packet_put_string(mic.value, mic.length);
 651
 652                                 packet_send();
 653                         }
 654
 655                         buffer_free(&b);
 656                         gss_release_buffer(&ms, &mic);
 657                 }
 658         }
 659
 660         return status;
 661 }
 662
 663 void
 664 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 665 {
 666         Authctxt *authctxt = ctxt;
 667         Gssctxt *gssctxt;
 668         u_int oidlen;
 669         u_char *oidv;
 670
 671         if (authctxt == NULL)
 672                 fatal("input_gssapi_response: no authentication context");
 673         gssctxt = authctxt->methoddata;
 674
 675         /* Setup our OID */
 676         oidv = packet_get_string(&oidlen);
 677
 678         if (oidlen <= 2 ||
 679             oidv[0] != SSH_GSS_OIDTYPE ||
 680             oidv[1] != oidlen - 2) {
 681                 xfree(oidv);
 682                 debug("Badly encoded mechanism OID received");
 683                 userauth(authctxt, NULL);
 684                 return;
 685         }
 686
 687         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 688                 fatal("Server returned different OID than expected");
 689
 690         packet_check_eom();
 691
 692         xfree(oidv);
 693
 694         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 695                 /* Start again with next method on list */
 696                 debug("Trying to start again");
 697                 userauth(authctxt, NULL);
 698                 return;
 699         }
 700 }
 701
 702 void
 703 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 704 {
 705         Authctxt *authctxt = ctxt;
 706         gss_buffer_desc recv_tok;
 707         OM_uint32 status;
 708         u_int slen;
 709
 710         if (authctxt == NULL)
 711                 fatal("input_gssapi_response: no authentication context");
 712
 713         recv_tok.value = packet_get_string(&slen);
 714         recv_tok.length = slen; /* safe typecast */
 715
 716         packet_check_eom();
 717
 718         status = process_gssapi_token(ctxt, &recv_tok);
 719
 720         xfree(recv_tok.value);
 721
 722         if (GSS_ERROR(status)) {
 723                 /* Start again with the next method in the list */
 724                 userauth(authctxt, NULL);
 725                 return;
 726         }
 727 }
 728
 729 void
 730 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 731 {
 732         Authctxt *authctxt = ctxt;
 733         Gssctxt *gssctxt;
 734         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 735         gss_buffer_desc recv_tok;
 736         OM_uint32 status, ms;
 737         u_int len;
 738
 739         if (authctxt == NULL)
 740                 fatal("input_gssapi_response: no authentication context");
 741         gssctxt = authctxt->methoddata;
 742
 743         recv_tok.value = packet_get_string(&len);
 744         recv_tok.length = len;
 745
 746         packet_check_eom();
 747
 748         /* Stick it into GSSAPI and see what it says */
 749         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 750             &recv_tok, &send_tok, NULL);
 751
 752         xfree(recv_tok.value);
 753         gss_release_buffer(&ms, &send_tok);
 754
 755         /* Server will be returning a failed packet after this one */
 756 }
 757
 758 void
 759 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 760 {
 761         OM_uint32 maj, min;
 762         char *msg;
 763         char *lang;
 764
 765         maj=packet_get_int();
 766         min=packet_get_int();
 767         msg=packet_get_string(NULL);
 768         lang=packet_get_string(NULL);
 769
 770         packet_check_eom();
 771
 772         debug("Server GSSAPI Error:\n%s", msg);
 773         xfree(msg);
 774         xfree(lang);
 775 }
 776
 777 int
 778 userauth_gsskeyex(Authctxt *authctxt)
 779 {
 780         Buffer b;
 781         gss_buffer_desc gssbuf;
 782         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 783         OM_uint32 ms;
 784
 785         static int attempt = 0;
 786         if (attempt++ >= 1)
 787                 return (0);
 788
 789         if (gss_kex_context == NULL) {
 790                 debug("No valid Key exchange context");
 791                 return (0);
 792         }
 793
 794         ssh_gssapi_buildmic(&b, authctxt->server_user, authctxt->service,
 795             "gssapi-keyex");
 796
 797         gssbuf.value = buffer_ptr(&b);
 798         gssbuf.length = buffer_len(&b);
 799
 800         if (GSS_ERROR(ssh_gssapi_sign(gss_kex_context, &gssbuf, &mic))) {
 801                 buffer_free(&b);
 802                 return (0);
 803         }
 804
 805         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 806         packet_put_cstring(authctxt->server_user);
 807         packet_put_cstring(authctxt->service);
 808         packet_put_cstring(authctxt->method->name);
 809         packet_put_string(mic.value, mic.length);
 810         packet_send();
 811
 812         buffer_free(&b);
 813         gss_release_buffer(&ms, &mic);
 814
 815         return (1);
 816 }
 817
 818 #endif /* GSSAPI */
 819
 820 int
 821 userauth_none(Authctxt *authctxt)
 822 {
 823         /* initial userauth request */
 824         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 825         packet_put_cstring(authctxt->server_user);
 826         packet_put_cstring(authctxt->service);
 827         packet_put_cstring(authctxt->method->name);
 828         packet_send();
 829         return 1;
 830 }
 831
 832 int
 833 userauth_passwd(Authctxt *authctxt)
 834 {
 835         static int attempt = 0;
 836         char prompt[150];
 837         char *password;
 838
 839         if (attempt++ >= options.number_of_password_prompts)
 840                 return 0;
 841
 842         if (attempt != 1)
 843                 error("Permission denied, please try again.");
 844
 845         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 846             authctxt->server_user, authctxt->host);
 847         password = read_passphrase(prompt, 0);
 848         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 849         packet_put_cstring(authctxt->server_user);
 850         packet_put_cstring(authctxt->service);
 851         packet_put_cstring(authctxt->method->name);
 852         packet_put_char(0);
 853         packet_put_cstring(password);
 854         memset(password, 0, strlen(password));
 855         xfree(password);
 856         packet_add_padding(64);
 857         packet_send();
 858
 859         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 860             &input_userauth_passwd_changereq);
 861
 862         return 1;
 863 }
 864 /*
 865  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 866  */
 867 void
 868 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 869 {
 870         Authctxt *authctxt = ctxt;
 871         char *info, *lang, *password = NULL, *retype = NULL;
 872         char prompt[150];
 873
 874         debug2("input_userauth_passwd_changereq");
 875
 876         if (authctxt == NULL)
 877                 fatal("input_userauth_passwd_changereq: "
 878                     "no authentication context");
 879
 880         info = packet_get_string(NULL);
 881         lang = packet_get_string(NULL);
 882         if (strlen(info) > 0)
 883                 logit("%s", info);
 884         xfree(info);
 885         xfree(lang);
 886         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 887         packet_put_cstring(authctxt->server_user);
 888         packet_put_cstring(authctxt->service);
 889         packet_put_cstring(authctxt->method->name);
 890         packet_put_char(1);                     /* additional info */
 891         snprintf(prompt, sizeof(prompt),
 892             "Enter %.30s@%.128s's old password: ",
 893             authctxt->server_user, authctxt->host);
 894         password = read_passphrase(prompt, 0);
 895         packet_put_cstring(password);
 896         memset(password, 0, strlen(password));
 897         xfree(password);
 898         password = NULL;
 899         while (password == NULL) {
 900                 snprintf(prompt, sizeof(prompt),
 901                     "Enter %.30s@%.128s's new password: ",
 902                     authctxt->server_user, authctxt->host);
 903                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 904                 if (password == NULL) {
 905                         /* bail out */
 906                         return;
 907                 }
 908                 snprintf(prompt, sizeof(prompt),
 909                     "Retype %.30s@%.128s's new password: ",
 910                     authctxt->server_user, authctxt->host);
 911                 retype = read_passphrase(prompt, 0);
 912                 if (strcmp(password, retype) != 0) {
 913                         memset(password, 0, strlen(password));
 914                         xfree(password);
 915                         logit("Mismatch; try again, EOF to quit.");
 916                         password = NULL;
 917                 }
 918                 memset(retype, 0, strlen(retype));
 919                 xfree(retype);
 920         }
 921         packet_put_cstring(password);
 922         memset(password, 0, strlen(password));
 923         xfree(password);
 924         packet_add_padding(64);
 925         packet_send();
 926
 927         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 928             &input_userauth_passwd_changereq);
 929 }
 930
 931 static int
 932 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
 933     u_char *data, u_int datalen)
 934 {
 935         Key *prv;
 936         int ret;
 937
 938         /* the agent supports this key */
 939         if (id->ac)
 940                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
 941                     data, datalen));
 942         /*
 943          * we have already loaded the private key or
 944          * the private key is stored in external hardware
 945          */
 946         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
 947                 return (key_sign(id->key, sigp, lenp, data, datalen));
 948         /* load the private key from the file */
 949         if ((prv = load_identity_file(id->filename)) == NULL)
 950                 return (-1);
 951         ret = key_sign(prv, sigp, lenp, data, datalen);
 952         key_free(prv);
 953         return (ret);
 954 }
 955
 956 static int
 957 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
 958 {
 959         Buffer b;
 960         u_char *blob, *signature;
 961         u_int bloblen, slen;
 962         u_int skip = 0;
 963         int ret = -1;
 964         int have_sig = 1;
 965
 966         debug3("sign_and_send_pubkey");
 967
 968         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
 969                 /* we cannot handle this key */
 970                 debug3("sign_and_send_pubkey: cannot handle key");
 971                 return 0;
 972         }
 973         /* data to be signed */
 974         buffer_init(&b);
 975         if (datafellows & SSH_OLD_SESSIONID) {
 976                 buffer_append(&b, session_id2, session_id2_len);
 977                 skip = session_id2_len;
 978         } else {
 979                 buffer_put_string(&b, session_id2, session_id2_len);
 980                 skip = buffer_len(&b);
 981         }
 982         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
 983         buffer_put_cstring(&b, authctxt->server_user);
 984         buffer_put_cstring(&b,
 985             datafellows & SSH_BUG_PKSERVICE ?
 986             "ssh-userauth" :
 987             authctxt->service);
 988         if (datafellows & SSH_BUG_PKAUTH) {
 989                 buffer_put_char(&b, have_sig);
 990         } else {
 991                 buffer_put_cstring(&b, authctxt->method->name);
 992                 buffer_put_char(&b, have_sig);
 993                 buffer_put_cstring(&b, key_ssh_name(id->key));
 994         }
 995         buffer_put_string(&b, blob, bloblen);
 996
 997         /* generate signature */
 998         ret = identity_sign(id, &signature, &slen,
 999             buffer_ptr(&b), buffer_len(&b));
1000         if (ret == -1) {
1001                 xfree(blob);
1002                 buffer_free(&b);
1003                 return 0;
1004         }
1005 #ifdef DEBUG_PK
1006         buffer_dump(&b);
1007 #endif
1008         if (datafellows & SSH_BUG_PKSERVICE) {
1009                 buffer_clear(&b);
1010                 buffer_append(&b, session_id2, session_id2_len);
1011                 skip = session_id2_len;
1012                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1013                 buffer_put_cstring(&b, authctxt->server_user);
1014                 buffer_put_cstring(&b, authctxt->service);
1015                 buffer_put_cstring(&b, authctxt->method->name);
1016                 buffer_put_char(&b, have_sig);
1017                 if (!(datafellows & SSH_BUG_PKAUTH))
1018                         buffer_put_cstring(&b, key_ssh_name(id->key));
1019                 buffer_put_string(&b, blob, bloblen);
1020         }
1021         xfree(blob);
1022
1023         /* append signature */
1024         buffer_put_string(&b, signature, slen);
1025         xfree(signature);
1026
1027         /* skip session id and packet type */
1028         if (buffer_len(&b) < skip + 1)
1029                 fatal("userauth_pubkey: internal error");
1030         buffer_consume(&b, skip + 1);
1031
1032         /* put remaining data from buffer into packet */
1033         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1034         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1035         buffer_free(&b);
1036         packet_send();
1037
1038         return 1;
1039 }
1040
1041 static int
1042 send_pubkey_test(Authctxt *authctxt, Identity *id)
1043 {
1044         u_char *blob;
1045         u_int bloblen, have_sig = 0;
1046
1047         debug3("send_pubkey_test");
1048
1049         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1050                 /* we cannot handle this key */
1051                 debug3("send_pubkey_test: cannot handle key");
1052                 return 0;
1053         }
1054         /* register callback for USERAUTH_PK_OK message */
1055         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1056
1057         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1058         packet_put_cstring(authctxt->server_user);
1059         packet_put_cstring(authctxt->service);
1060         packet_put_cstring(authctxt->method->name);
1061         packet_put_char(have_sig);
1062         if (!(datafellows & SSH_BUG_PKAUTH))
1063                 packet_put_cstring(key_ssh_name(id->key));
1064         packet_put_string(blob, bloblen);
1065         xfree(blob);
1066         packet_send();
1067         return 1;
1068 }
1069
1070 static Key *
1071 load_identity_file(char *filename)
1072 {
1073         Key *private;
1074         char prompt[300], *passphrase;
1075         int perm_ok, quit, i;
1076         struct stat st;
1077
1078         if (stat(filename, &st) < 0) {
1079                 debug3("no such identity: %s", filename);
1080                 return NULL;
1081         }
1082         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1083         if (!perm_ok)
1084                 return NULL;
1085         if (private == NULL) {
1086                 if (options.batch_mode)
1087                         return NULL;
1088                 snprintf(prompt, sizeof prompt,
1089                     "Enter passphrase for key '%.100s': ", filename);
1090                 for (i = 0; i < options.number_of_password_prompts; i++) {
1091                         passphrase = read_passphrase(prompt, 0);
1092                         if (strcmp(passphrase, "") != 0) {
1093                                 private = key_load_private_type(KEY_UNSPEC,
1094                                     filename, passphrase, NULL, NULL);
1095                                 quit = 0;
1096                         } else {
1097                                 debug2("no passphrase given, try next key");
1098                                 quit = 1;
1099                         }
1100                         memset(passphrase, 0, strlen(passphrase));
1101                         xfree(passphrase);
1102                         if (private != NULL || quit)
1103                                 break;
1104                         debug2("bad passphrase given, try again...");
1105                 }
1106         }
1107         return private;
1108 }
1109
1110 /*
1111  * try keys in the following order:
1112  *      1. agent keys that are found in the config file
1113  *      2. other agent keys
1114  *      3. keys that are only listed in the config file
1115  */
1116 static void
1117 pubkey_prepare(Authctxt *authctxt)
1118 {
1119         Identity *id;
1120         Idlist agent, files, *preferred;
1121         Key *key;
1122         AuthenticationConnection *ac;
1123         char *comment;
1124         int i, found;
1125
1126         TAILQ_INIT(&agent);     /* keys from the agent */
1127         TAILQ_INIT(&files);     /* keys from the config file */
1128         preferred = &authctxt->keys;
1129         TAILQ_INIT(preferred);  /* preferred order of keys */
1130
1131         /* list of keys stored in the filesystem */
1132         for (i = 0; i < options.num_identity_files; i++) {
1133                 key = options.identity_keys[i];
1134                 if (key && key->type == KEY_RSA1)
1135                         continue;
1136                 options.identity_keys[i] = NULL;
1137                 id = xcalloc(1, sizeof(*id));
1138                 id->key = key;
1139                 id->filename = xstrdup(options.identity_files[i]);
1140                 TAILQ_INSERT_TAIL(&files, id, next);
1141         }
1142         /* list of keys supported by the agent */
1143         if ((ac = ssh_get_authentication_connection())) {
1144                 for (key = ssh_get_first_identity(ac, &comment, 2);
1145                     key != NULL;
1146                     key = ssh_get_next_identity(ac, &comment, 2)) {
1147                         found = 0;
1148                         TAILQ_FOREACH(id, &files, next) {
1149                                 /* agent keys from the config file are preferred */
1150                                 if (key_equal(key, id->key)) {
1151                                         key_free(key);
1152                                         xfree(comment);
1153                                         TAILQ_REMOVE(&files, id, next);
1154                                         TAILQ_INSERT_TAIL(preferred, id, next);
1155                                         id->ac = ac;
1156                                         found = 1;
1157                                         break;
1158                                 }
1159                         }
1160                         if (!found && !options.identities_only) {
1161                                 id = xcalloc(1, sizeof(*id));
1162                                 id->key = key;
1163                                 id->filename = comment;
1164                                 id->ac = ac;
1165                                 TAILQ_INSERT_TAIL(&agent, id, next);
1166                         }
1167                 }
1168                 /* append remaining agent keys */
1169                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1170                         TAILQ_REMOVE(&agent, id, next);
1171                         TAILQ_INSERT_TAIL(preferred, id, next);
1172                 }
1173                 authctxt->agent = ac;
1174         }
1175         /* append remaining keys from the config file */
1176         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1177                 TAILQ_REMOVE(&files, id, next);
1178                 TAILQ_INSERT_TAIL(preferred, id, next);
1179         }
1180         TAILQ_FOREACH(id, preferred, next) {
1181                 debug2("key: %s (%p)", id->filename, id->key);
1182         }
1183 }
1184
1185 static void
1186 pubkey_cleanup(Authctxt *authctxt)
1187 {
1188         Identity *id;
1189
1190         if (authctxt->agent != NULL)
1191                 ssh_close_authentication_connection(authctxt->agent);
1192         for (id = TAILQ_FIRST(&authctxt->keys); id;
1193             id = TAILQ_FIRST(&authctxt->keys)) {
1194                 TAILQ_REMOVE(&authctxt->keys, id, next);
1195                 if (id->key)
1196                         key_free(id->key);
1197                 if (id->filename)
1198                         xfree(id->filename);
1199                 xfree(id);
1200         }
1201 }
1202
1203 int
1204 userauth_pubkey(Authctxt *authctxt)
1205 {
1206         Identity *id;
1207         int sent = 0;
1208
1209         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1210                 if (id->tried++)
1211                         return (0);
1212                 /* move key to the end of the queue */
1213                 TAILQ_REMOVE(&authctxt->keys, id, next);
1214                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1215                 /*
1216                  * send a test message if we have the public key. for
1217                  * encrypted keys we cannot do this and have to load the
1218                  * private key instead
1219                  */
1220                 if (id->key && id->key->type != KEY_RSA1) {
1221                         debug("Offering public key: %s", id->filename);
1222                         sent = send_pubkey_test(authctxt, id);
1223                 } else if (id->key == NULL) {
1224                         debug("Trying private key: %s", id->filename);
1225                         id->key = load_identity_file(id->filename);
1226                         if (id->key != NULL) {
1227                                 id->isprivate = 1;
1228                                 sent = sign_and_send_pubkey(authctxt, id);
1229                                 key_free(id->key);
1230                                 id->key = NULL;
1231                         }
1232                 }
1233                 if (sent)
1234                         return (sent);
1235         }
1236         return (0);
1237 }
1238
1239 /*
1240  * Send userauth request message specifying keyboard-interactive method.
1241  */
1242 int
1243 userauth_kbdint(Authctxt *authctxt)
1244 {
1245         static int attempt = 0;
1246
1247         if (attempt++ >= options.number_of_password_prompts)
1248                 return 0;
1249         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1250         if (attempt > 1 && !authctxt->info_req_seen) {
1251                 debug3("userauth_kbdint: disable: no info_req_seen");
1252                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1253                 return 0;
1254         }
1255
1256         debug2("userauth_kbdint");
1257         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1258         packet_put_cstring(authctxt->server_user);
1259         packet_put_cstring(authctxt->service);
1260         packet_put_cstring(authctxt->method->name);
1261         packet_put_cstring("");                                 /* lang */
1262         packet_put_cstring(options.kbd_interactive_devices ?
1263             options.kbd_interactive_devices : "");
1264         packet_send();
1265
1266         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1267         return 1;
1268 }
1269
1270 /*
1271  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1272  */
1273 void
1274 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1275 {
1276         Authctxt *authctxt = ctxt;
1277         char *name, *inst, *lang, *prompt, *response;
1278         u_int num_prompts, i;
1279         int echo = 0;
1280
1281         debug2("input_userauth_info_req");
1282
1283         if (authctxt == NULL)
1284                 fatal("input_userauth_info_req: no authentication context");
1285
1286         authctxt->info_req_seen = 1;
1287
1288         name = packet_get_string(NULL);
1289         inst = packet_get_string(NULL);
1290         lang = packet_get_string(NULL);
1291         if (strlen(name) > 0)
1292                 logit("%s", name);
1293         if (strlen(inst) > 0)
1294                 logit("%s", inst);
1295         xfree(name);
1296         xfree(inst);
1297         xfree(lang);
1298
1299         num_prompts = packet_get_int();
1300         /*
1301          * Begin to build info response packet based on prompts requested.
1302          * We commit to providing the correct number of responses, so if
1303          * further on we run into a problem that prevents this, we have to
1304          * be sure and clean this up and send a correct error response.
1305          */
1306         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1307         packet_put_int(num_prompts);
1308
1309         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1310         for (i = 0; i < num_prompts; i++) {
1311                 prompt = packet_get_string(NULL);
1312                 echo = packet_get_char();
1313
1314                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1315
1316                 packet_put_cstring(response);
1317                 memset(response, 0, strlen(response));
1318                 xfree(response);
1319                 xfree(prompt);
1320         }
1321         packet_check_eom(); /* done with parsing incoming message. */
1322
1323         packet_add_padding(64);
1324         packet_send();
1325 }
1326
1327 static int
1328 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1329     u_char *data, u_int datalen)
1330 {
1331         Buffer b;
1332         struct stat st;
1333         pid_t pid;
1334         int to[2], from[2], status, version = 2;
1335
1336         debug2("ssh_keysign called");
1337
1338         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1339                 error("ssh_keysign: no installed: %s", strerror(errno));
1340                 return -1;
1341         }
1342         if (fflush(stdout) != 0)
1343                 error("ssh_keysign: fflush: %s", strerror(errno));
1344         if (pipe(to) < 0) {
1345                 error("ssh_keysign: pipe: %s", strerror(errno));
1346                 return -1;
1347         }
1348         if (pipe(from) < 0) {
1349                 error("ssh_keysign: pipe: %s", strerror(errno));
1350                 return -1;
1351         }
1352         if ((pid = fork()) < 0) {
1353                 error("ssh_keysign: fork: %s", strerror(errno));
1354                 return -1;
1355         }
1356         if (pid == 0) {
1357                 permanently_drop_suid(getuid());
1358                 close(from[0]);
1359                 if (dup2(from[1], STDOUT_FILENO) < 0)
1360                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1361                 close(to[1]);
1362                 if (dup2(to[0], STDIN_FILENO) < 0)
1363                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1364                 close(from[1]);
1365                 close(to[0]);
1366                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1367                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1368                     strerror(errno));
1369         }
1370         close(from[1]);
1371         close(to[0]);
1372
1373         buffer_init(&b);
1374         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1375         buffer_put_string(&b, data, datalen);
1376         if (ssh_msg_send(to[1], version, &b) == -1)
1377                 fatal("ssh_keysign: couldn't send request");
1378
1379         if (ssh_msg_recv(from[0], &b) < 0) {
1380                 error("ssh_keysign: no reply");
1381                 buffer_free(&b);
1382                 return -1;
1383         }
1384         close(from[0]);
1385         close(to[1]);
1386
1387         while (waitpid(pid, &status, 0) < 0)
1388                 if (errno != EINTR)
1389                         break;
1390
1391         if (buffer_get_char(&b) != version) {
1392                 error("ssh_keysign: bad version");
1393                 buffer_free(&b);
1394                 return -1;
1395         }
1396         *sigp = buffer_get_string(&b, lenp);
1397         buffer_free(&b);
1398
1399         return 0;
1400 }
1401
1402 int
1403 userauth_hostbased(Authctxt *authctxt)
1404 {
1405         Key *private = NULL;
1406         Sensitive *sensitive = authctxt->sensitive;
1407         Buffer b;
1408         u_char *signature, *blob;
1409         char *chost, *pkalg, *p;
1410         const char *service;
1411         u_int blen, slen;
1412         int ok, i, len, found = 0;
1413
1414         /* check for a useful key */
1415         for (i = 0; i < sensitive->nkeys; i++) {
1416                 private = sensitive->keys[i];
1417                 if (private && private->type != KEY_RSA1) {
1418                         found = 1;
1419                         /* we take and free the key */
1420                         sensitive->keys[i] = NULL;
1421                         break;
1422                 }
1423         }
1424         if (!found) {
1425                 debug("No more client hostkeys for hostbased authentication.");
1426                 return 0;
1427         }
1428         if (key_to_blob(private, &blob, &blen) == 0) {
1429                 key_free(private);
1430                 return 0;
1431         }
1432         /* figure out a name for the client host */
1433         p = get_local_name(packet_get_connection_in());
1434         if (p == NULL) {
1435                 error("userauth_hostbased: cannot get local ipaddr/name");
1436                 key_free(private);
1437                 xfree(blob);
1438                 return 0;
1439         }
1440         len = strlen(p) + 2;
1441         xasprintf(&chost, "%s.", p);
1442         debug2("userauth_hostbased: chost %s", chost);
1443         xfree(p);
1444
1445         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1446             authctxt->service;
1447         pkalg = xstrdup(key_ssh_name(private));
1448         buffer_init(&b);
1449         /* construct data */
1450         buffer_put_string(&b, session_id2, session_id2_len);
1451         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1452         buffer_put_cstring(&b, authctxt->server_user);
1453         buffer_put_cstring(&b, service);
1454         buffer_put_cstring(&b, authctxt->method->name);
1455         buffer_put_cstring(&b, pkalg);
1456         buffer_put_string(&b, blob, blen);
1457         buffer_put_cstring(&b, chost);
1458         buffer_put_cstring(&b, authctxt->local_user);
1459 #ifdef DEBUG_PK
1460         buffer_dump(&b);
1461 #endif
1462         if (sensitive->external_keysign)
1463                 ok = ssh_keysign(private, &signature, &slen,
1464                     buffer_ptr(&b), buffer_len(&b));
1465         else
1466                 ok = key_sign(private, &signature, &slen,
1467                     buffer_ptr(&b), buffer_len(&b));
1468         key_free(private);
1469         buffer_free(&b);
1470         if (ok != 0) {
1471                 error("key_sign failed");
1472                 xfree(chost);
1473                 xfree(pkalg);
1474                 xfree(blob);
1475                 return 0;
1476         }
1477         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1478         packet_put_cstring(authctxt->server_user);
1479         packet_put_cstring(authctxt->service);
1480         packet_put_cstring(authctxt->method->name);
1481         packet_put_cstring(pkalg);
1482         packet_put_string(blob, blen);
1483         packet_put_cstring(chost);
1484         packet_put_cstring(authctxt->local_user);
1485         packet_put_string(signature, slen);
1486         memset(signature, 's', slen);
1487         xfree(signature);
1488         xfree(chost);
1489         xfree(pkalg);
1490         xfree(blob);
1491
1492         packet_send();
1493         return 1;
1494 }
1495
1496 /* find auth method */
1497
1498 /*
1499  * given auth method name, if configurable options permit this method fill
1500  * in auth_ident field and return true, otherwise return false.
1501  */
1502 static int
1503 authmethod_is_enabled(Authmethod *method)
1504 {
1505         if (method == NULL)
1506                 return 0;
1507         /* return false if options indicate this method is disabled */
1508         if  (method->enabled == NULL || *method->enabled == 0)
1509                 return 0;
1510         /* return false if batch mode is enabled but method needs interactive mode */
1511         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1512                 return 0;
1513         return 1;
1514 }
1515
1516 static Authmethod *
1517 authmethod_lookup(const char *name)
1518 {
1519         Authmethod *method = NULL;
1520         if (name != NULL)
1521                 for (method = authmethods; method->name != NULL; method++)
1522                         if (strcmp(name, method->name) == 0)
1523                                 return method;
1524         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1525         return NULL;
1526 }
1527
1528 /* XXX internal state */
1529 static Authmethod *current = NULL;
1530 static char *supported = NULL;
1531 static char *preferred = NULL;
1532
1533 /*
1534  * Given the authentication method list sent by the server, return the
1535  * next method we should try.  If the server initially sends a nil list,
1536  * use a built-in default list.
1537  */
1538 static Authmethod *
1539 authmethod_get(char *authlist)
1540 {
1541         char *name = NULL;
1542         u_int next;
1543
1544         /* Use a suitable default if we're passed a nil list.  */
1545         if (authlist == NULL || strlen(authlist) == 0)
1546                 authlist = options.preferred_authentications;
1547
1548         if (supported == NULL || strcmp(authlist, supported) != 0) {
1549                 debug3("start over, passed a different list %s", authlist);
1550                 if (supported != NULL)
1551                         xfree(supported);
1552                 supported = xstrdup(authlist);
1553                 preferred = options.preferred_authentications;
1554                 debug3("preferred %s", preferred);
1555                 current = NULL;
1556         } else if (current != NULL && authmethod_is_enabled(current))
1557                 return current;
1558
1559         for (;;) {
1560                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1561                         debug("No more authentication methods to try.");
1562                         current = NULL;
1563                         return NULL;
1564                 }
1565                 preferred += next;
1566                 debug3("authmethod_lookup %s", name);
1567                 debug3("remaining preferred: %s", preferred);
1568                 if ((current = authmethod_lookup(name)) != NULL &&
1569                     authmethod_is_enabled(current)) {
1570                         debug3("authmethod_is_enabled %s", name);
1571                         debug("Next authentication method: %s", name);
1572                         return current;
1573                 }
1574         }
1575 }
1576
1577 static char *
1578 authmethods_get(void)
1579 {
1580         Authmethod *method = NULL;
1581         Buffer b;
1582         char *list;
1583
1584         buffer_init(&b);
1585         for (method = authmethods; method->name != NULL; method++) {
1586                 if (authmethod_is_enabled(method)) {
1587                         if (buffer_len(&b) > 0)
1588                                 buffer_append(&b, ",", 1);
1589                         buffer_append(&b, method->name, strlen(method->name));
1590                 }
1591         }
1592         buffer_append(&b, "\0", 1);
1593         list = xstrdup(buffer_ptr(&b));
1594         buffer_free(&b);
1595         return list;
1596 }