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 1.142 2005/08/30 22:08:05 djm 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
  62 /*
  63  * SSH2 key exchange
  64  */
  65
  66 u_char *session_id2 = NULL;
  67 u_int session_id2_len = 0;
  68
  69 char *xxx_host;
  70 struct sockaddr *xxx_hostaddr;
  71
  72 Kex *xxx_kex = NULL;
  73
  74 static int
  75 verify_host_key_callback(Key *hostkey)
  76 {
  77         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
  78                 fatal("Host key verification failed.");
  79         return 0;
  80 }
  81
  82 void
  83 ssh_kex2(char *host, struct sockaddr *hostaddr)
  84 {
  85         Kex *kex;
  86 #ifdef GSSAPI
  87         char *orig=NULL, *gss=NULL;
  88         int len;
  89 #endif
  90
  91         xxx_host = host;
  92         xxx_hostaddr = hostaddr;
  93
  94 #ifdef GSSAPI
  95         if (options.gss_keyex) {
  96         /* Add the GSSAPI mechanisms currently supported on this client to
  97          * the key exchange algorithm proposal */
  98         orig = myproposal[PROPOSAL_KEX_ALGS];
  99         gss = ssh_gssapi_client_mechanisms((char *)get_canonical_hostname(1));
 100         if (gss) {
 101            len = strlen(orig)+strlen(gss)+2;
 102            myproposal[PROPOSAL_KEX_ALGS]=xmalloc(len);
 103            snprintf(myproposal[PROPOSAL_KEX_ALGS],len,"%s,%s",gss,orig);
 104         }
 105         }
 106 #endif
 107
 108         if (options.ciphers == (char *)-1) {
 109                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 110                 options.ciphers = NULL;
 111         }
 112         if (options.ciphers != NULL) {
 113                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 114                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 115         }
 116         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 117             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 118         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 119             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 120         if (options.compression) {
 121                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 122                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 123         } else {
 124                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 125                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 126         }
 127         if (options.macs != NULL) {
 128                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 129                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 130         }
 131         if (options.hostkeyalgorithms != NULL)
 132                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 133                     options.hostkeyalgorithms;
 134
 135 #ifdef GSSAPI
 136         /* If we've got GSSAPI algorithms, then we also support the
 137          * 'null' hostkey, as a last resort */
 138         if (options.gss_keyex && gss) {
 139                 orig=myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
 140                 len = strlen(orig)+sizeof(",null");
 141                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]=xmalloc(len);
 142                 snprintf(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS],len,"%s,null",orig);
 143         }
 144 #endif
 145
 146         if (options.rekey_limit)
 147                 packet_set_rekey_limit(options.rekey_limit);
 148
 149         /* start key exchange */
 150         kex = kex_setup(myproposal);
 151         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 152         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 153         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 154 #ifdef GSSAPI
 155         kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client;
 156 #endif
 157         kex->client_version_string=client_version_string;
 158         kex->server_version_string=server_version_string;
 159         kex->verify_host_key=&verify_host_key_callback;
 160 #ifdef GSSAPI
 161         kex->options.gss_deleg_creds=options.gss_deleg_creds;
 162 #endif
 163
 164         xxx_kex = kex;
 165
 166         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 167
 168         session_id2 = kex->session_id;
 169         session_id2_len = kex->session_id_len;
 170
 171 #ifdef DEBUG_KEXDH
 172         /* send 1st encrypted/maced/compressed message */
 173         packet_start(SSH2_MSG_IGNORE);
 174         packet_put_cstring("markus");
 175         packet_send();
 176         packet_write_wait();
 177 #endif
 178 }
 179
 180 /*
 181  * Authenticate user
 182  */
 183
 184 typedef struct Authctxt Authctxt;
 185 typedef struct Authmethod Authmethod;
 186 typedef struct identity Identity;
 187 typedef struct idlist Idlist;
 188
 189 struct identity {
 190         TAILQ_ENTRY(identity) next;
 191         AuthenticationConnection *ac;   /* set if agent supports key */
 192         Key     *key;                   /* public/private key */
 193         char    *filename;              /* comment for agent-only keys */
 194         int     tried;
 195         int     isprivate;              /* key points to the private key */
 196 };
 197 TAILQ_HEAD(idlist, identity);
 198
 199 struct Authctxt {
 200         const char *server_user;
 201         const char *local_user;
 202         const char *host;
 203         const char *service;
 204         Authmethod *method;
 205         int success;
 206         char *authlist;
 207         /* pubkey */
 208         Idlist keys;
 209         AuthenticationConnection *agent;
 210         /* hostbased */
 211         Sensitive *sensitive;
 212         /* kbd-interactive */
 213         int info_req_seen;
 214         /* generic */
 215         void *methoddata;
 216 };
 217 struct Authmethod {
 218         char    *name;          /* string to compare against server's list */
 219         int     (*userauth)(Authctxt *authctxt);
 220         int     *enabled;       /* flag in option struct that enables method */
 221         int     *batch_flag;    /* flag in option struct that disables method */
 222 };
 223
 224 void    input_userauth_success(int, u_int32_t, void *);
 225 void    input_userauth_failure(int, u_int32_t, void *);
 226 void    input_userauth_banner(int, u_int32_t, void *);
 227 void    input_userauth_error(int, u_int32_t, void *);
 228 void    input_userauth_info_req(int, u_int32_t, void *);
 229 void    input_userauth_pk_ok(int, u_int32_t, void *);
 230 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 231
 232 int     userauth_none(Authctxt *);
 233 int     userauth_pubkey(Authctxt *);
 234 int     userauth_passwd(Authctxt *);
 235 int     userauth_kbdint(Authctxt *);
 236 int     userauth_hostbased(Authctxt *);
 237 int     userauth_kerberos(Authctxt *);
 238
 239 #ifdef GSSAPI
 240 int     userauth_gssapi(Authctxt *authctxt);
 241 void    input_gssapi_response(int type, u_int32_t, void *);
 242 void    input_gssapi_token(int type, u_int32_t, void *);
 243 void    input_gssapi_hash(int type, u_int32_t, void *);
 244 void    input_gssapi_error(int, u_int32_t, void *);
 245 void    input_gssapi_errtok(int, u_int32_t, void *);
 246 #endif
 247
 248 #ifdef GSSAPI
 249 int     userauth_external(Authctxt *authctxt);
 250 int     userauth_gssapi(Authctxt *authctxt);
 251 int     userauth_gssapi_with_mic(Authctxt *authctxt);
 252 int     userauth_gssapi_without_mic(Authctxt *authctxt);
 253 void    input_gssapi_response(int type, u_int32_t, void *);
 254 void    input_gssapi_token(int type, u_int32_t, void *);
 255 void    input_gssapi_hash(int type, u_int32_t, void *);
 256 void    input_gssapi_error(int, u_int32_t, void *);
 257 void    input_gssapi_errtok(int, u_int32_t, void *);
 258 #endif
 259
 260 void    userauth(Authctxt *, char *);
 261
 262 static int sign_and_send_pubkey(Authctxt *, Identity *);
 263 static void pubkey_prepare(Authctxt *);
 264 static void pubkey_cleanup(Authctxt *);
 265 static Key *load_identity_file(char *);
 266
 267 static Authmethod *authmethod_get(char *authlist);
 268 static Authmethod *authmethod_lookup(const char *name);
 269 static char *authmethods_get(void);
 270
 271 Authmethod authmethods[] = {
 272 #ifdef GSSAPI
 273         {"external-keyx",
 274                 userauth_external,
 275                 &options.gss_authentication,
 276                 NULL},
 277         {"gssapi-with-mic",
 278                 userauth_gssapi,
 279                 &options.gss_authentication,
 280                 NULL},
 281         {"gssapi",
 282                 userauth_gssapi,
 283                 &options.gss_authentication,
 284                 NULL},
 285 #endif
 286         {"hostbased",
 287                 userauth_hostbased,
 288                 &options.hostbased_authentication,
 289                 NULL},
 290         {"publickey",
 291                 userauth_pubkey,
 292                 &options.pubkey_authentication,
 293                 NULL},
 294         {"keyboard-interactive",
 295                 userauth_kbdint,
 296                 &options.kbd_interactive_authentication,
 297                 &options.batch_mode},
 298         {"password",
 299                 userauth_passwd,
 300                 &options.password_authentication,
 301                 &options.batch_mode},
 302         {"none",
 303                 userauth_none,
 304                 NULL,
 305                 NULL},
 306         {NULL, NULL, NULL, NULL}
 307 };
 308
 309 void
 310 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 311     Sensitive *sensitive)
 312 {
 313         Authctxt authctxt;
 314         int type;
 315
 316         if (options.challenge_response_authentication)
 317                 options.kbd_interactive_authentication = 1;
 318
 319         packet_start(SSH2_MSG_SERVICE_REQUEST);
 320         packet_put_cstring("ssh-userauth");
 321         packet_send();
 322         debug("SSH2_MSG_SERVICE_REQUEST sent");
 323         packet_write_wait();
 324         type = packet_read();
 325         if (type != SSH2_MSG_SERVICE_ACCEPT)
 326                 fatal("Server denied authentication request: %d", type);
 327         if (packet_remaining() > 0) {
 328                 char *reply = packet_get_string(NULL);
 329                 debug2("service_accept: %s", reply);
 330                 xfree(reply);
 331         } else {
 332                 debug2("buggy server: service_accept w/o service");
 333         }
 334         packet_check_eom();
 335         debug("SSH2_MSG_SERVICE_ACCEPT received");
 336
 337         if (options.preferred_authentications == NULL)
 338                 options.preferred_authentications = authmethods_get();
 339
 340         /* setup authentication context */
 341         memset(&authctxt, 0, sizeof(authctxt));
 342         pubkey_prepare(&authctxt);
 343         authctxt.server_user = server_user;
 344         authctxt.local_user = local_user;
 345         authctxt.host = host;
 346         authctxt.service = "ssh-connection";            /* service name */
 347         authctxt.success = 0;
 348         authctxt.method = authmethod_lookup("none");
 349         authctxt.authlist = NULL;
 350         authctxt.methoddata = NULL;
 351         authctxt.sensitive = sensitive;
 352         authctxt.info_req_seen = 0;
 353         if (authctxt.method == NULL)
 354                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 355
 356         /* initial userauth request */
 357         userauth_none(&authctxt);
 358
 359         dispatch_init(&input_userauth_error);
 360         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 361         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 362         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 363         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 364
 365         pubkey_cleanup(&authctxt);
 366         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 367
 368         debug("Authentication succeeded (%s).", authctxt.method->name);
 369 }
 370
 371 void
 372 userauth(Authctxt *authctxt, char *authlist)
 373 {
 374         if (authctxt->methoddata) {
 375                 xfree(authctxt->methoddata);
 376                 authctxt->methoddata = NULL;
 377         }
 378         if (authlist == NULL) {
 379                 authlist = authctxt->authlist;
 380         } else {
 381                 if (authctxt->authlist)
 382                         xfree(authctxt->authlist);
 383                 authctxt->authlist = authlist;
 384         }
 385         for (;;) {
 386                 Authmethod *method = authmethod_get(authlist);
 387                 if (method == NULL)
 388                         fatal("Permission denied (%s).", authlist);
 389                 authctxt->method = method;
 390
 391                 /* reset the per method handler */
 392                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 393                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 394
 395                 /* and try new method */
 396                 if (method->userauth(authctxt) != 0) {
 397                         debug2("we sent a %s packet, wait for reply", method->name);
 398                         break;
 399                 } else {
 400                         debug2("we did not send a packet, disable method");
 401                         method->enabled = NULL;
 402                 }
 403         }
 404 }
 405
 406 void
 407 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 408 {
 409         fatal("input_userauth_error: bad message during authentication: "
 410             "type %d", type);
 411 }
 412
 413 void
 414 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 415 {
 416         char *msg, *lang;
 417
 418         debug3("input_userauth_banner");
 419         msg = packet_get_string(NULL);
 420         lang = packet_get_string(NULL);
 421         if (options.log_level > SYSLOG_LEVEL_QUIET)
 422                 fprintf(stderr, "%s", msg);
 423         xfree(msg);
 424         xfree(lang);
 425 }
 426
 427 void
 428 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 429 {
 430         Authctxt *authctxt = ctxt;
 431         if (authctxt == NULL)
 432                 fatal("input_userauth_success: no authentication context");
 433         if (authctxt->authlist) {
 434                 xfree(authctxt->authlist);
 435                 authctxt->authlist = NULL;
 436         }
 437         if (authctxt->methoddata) {
 438                 xfree(authctxt->methoddata);
 439                 authctxt->methoddata = NULL;
 440         }
 441         authctxt->success = 1;                  /* break out */
 442 }
 443
 444 void
 445 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 446 {
 447         Authctxt *authctxt = ctxt;
 448         char *authlist = NULL;
 449         int partial;
 450
 451         if (authctxt == NULL)
 452                 fatal("input_userauth_failure: no authentication context");
 453
 454         authlist = packet_get_string(NULL);
 455         partial = packet_get_char();
 456         packet_check_eom();
 457
 458         if (partial != 0)
 459                 logit("Authenticated with partial success.");
 460         debug("Authentications that can continue: %s", authlist);
 461
 462         userauth(authctxt, authlist);
 463 }
 464 void
 465 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 466 {
 467         Authctxt *authctxt = ctxt;
 468         Key *key = NULL;
 469         Identity *id = NULL;
 470         Buffer b;
 471         int pktype, sent = 0;
 472         u_int alen, blen;
 473         char *pkalg, *fp;
 474         u_char *pkblob;
 475
 476         if (authctxt == NULL)
 477                 fatal("input_userauth_pk_ok: no authentication context");
 478         if (datafellows & SSH_BUG_PKOK) {
 479                 /* this is similar to SSH_BUG_PKAUTH */
 480                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 481                 pkblob = packet_get_string(&blen);
 482                 buffer_init(&b);
 483                 buffer_append(&b, pkblob, blen);
 484                 pkalg = buffer_get_string(&b, &alen);
 485                 buffer_free(&b);
 486         } else {
 487                 pkalg = packet_get_string(&alen);
 488                 pkblob = packet_get_string(&blen);
 489         }
 490         packet_check_eom();
 491
 492         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 493
 494         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 495                 debug("unknown pkalg %s", pkalg);
 496                 goto done;
 497         }
 498         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 499                 debug("no key from blob. pkalg %s", pkalg);
 500                 goto done;
 501         }
 502         if (key->type != pktype) {
 503                 error("input_userauth_pk_ok: type mismatch "
 504                     "for decoded key (received %d, expected %d)",
 505                     key->type, pktype);
 506                 goto done;
 507         }
 508         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 509         debug2("input_userauth_pk_ok: fp %s", fp);
 510         xfree(fp);
 511
 512         /*
 513          * search keys in the reverse order, because last candidate has been
 514          * moved to the end of the queue.  this also avoids confusion by
 515          * duplicate keys
 516          */
 517         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 518                 if (key_equal(key, id->key)) {
 519                         sent = sign_and_send_pubkey(authctxt, id);
 520                         break;
 521                 }
 522         }
 523 done:
 524         if (key != NULL)
 525                 key_free(key);
 526         xfree(pkalg);
 527         xfree(pkblob);
 528
 529         /* try another method if we did not send a packet */
 530         if (sent == 0)
 531                 userauth(authctxt, NULL);
 532 }
 533
 534 #ifdef GSSAPI
 535 int
 536 userauth_gssapi(Authctxt *authctxt)
 537 {
 538         Gssctxt *gssctxt = NULL;
 539         static gss_OID_set gss_supported = NULL;
 540         static u_int mech = 0;
 541         OM_uint32 min;
 542         int ok = 0;
 543
 544         if (!options.gss_authentication) {
 545                 verbose("GSSAPI authentication disabled.");
 546                 return 0;
 547         }
 548
 549         /* Try one GSSAPI method at a time, rather than sending them all at
 550          * once. */
 551
 552         if (gss_supported == NULL)
 553                 gss_indicate_mechs(&min, &gss_supported);
 554
 555         /* Check to see if the mechanism is usable before we offer it */
 556         while (mech < gss_supported->count && !ok) {
 557                 if (gssctxt)
 558                         ssh_gssapi_delete_ctx(&gssctxt);
 559                 ssh_gssapi_build_ctx(&gssctxt);
 560                 ssh_gssapi_set_oid(gssctxt, &gss_supported->elements[mech]);
 561
 562                 /* My DER encoding requires length<128 */
 563                 if (gss_supported->elements[mech].length < 128 &&
 564                     ssh_gssapi_check_mechanism(&gss_supported->elements[mech],
 565                                                get_canonical_hostname(1)) &&
 566                     !GSS_ERROR(ssh_gssapi_import_name(gssctxt,
 567                                                 get_canonical_hostname(1)))) {
 568                         ok = 1; /* Mechanism works */
 569                 } else {
 570                         mech++;
 571                 }
 572         }
 573
 574         if (!ok)
 575                 return 0;
 576
 577         authctxt->methoddata=(void *)gssctxt;
 578
 579         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 580         packet_put_cstring(authctxt->server_user);
 581         packet_put_cstring(authctxt->service);
 582         packet_put_cstring(authctxt->method->name);
 583
 584         packet_put_int(1);
 585
 586         packet_put_int((gss_supported->elements[mech].length) + 2);
 587         packet_put_char(SSH_GSS_OIDTYPE);
 588         packet_put_char(gss_supported->elements[mech].length);
 589         packet_put_raw(gss_supported->elements[mech].elements,
 590             gss_supported->elements[mech].length);
 591
 592         packet_send();
 593
 594         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 595         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 596         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 597         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 598
 599         mech++; /* Move along to next candidate */
 600
 601         return 1;
 602 }
 603
 604 static OM_uint32
 605 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 606 {
 607         Authctxt *authctxt = ctxt;
 608         Gssctxt *gssctxt = authctxt->methoddata;
 609         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 610         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 611         gss_buffer_desc gssbuf;
 612         OM_uint32 status, ms, flags;
 613         Buffer b;
 614
 615         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 616             recv_tok, &send_tok, &flags);
 617
 618         if (send_tok.length > 0) {
 619                 if (GSS_ERROR(status))
 620                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 621                 else
 622                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 623
 624                 packet_put_string(send_tok.value, send_tok.length);
 625                 packet_send();
 626                 gss_release_buffer(&ms, &send_tok);
 627         }
 628
 629         if (status == GSS_S_COMPLETE) {
 630                 /* send either complete or MIC, depending on mechanism */
 631                 if (strcmp(authctxt->method->name,"gssapi")==0 ||
 632                     (!(flags & GSS_C_INTEG_FLAG))) {
 633                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 634                         packet_send();
 635                 } else {
 636                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 637                             authctxt->service, "gssapi-with-mic");
 638
 639                         gssbuf.value = buffer_ptr(&b);
 640                         gssbuf.length = buffer_len(&b);
 641
 642                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 643
 644                         if (!GSS_ERROR(status)) {
 645                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 646                                 packet_put_string(mic.value, mic.length);
 647
 648                                 packet_send();
 649                         }
 650
 651                         buffer_free(&b);
 652                         gss_release_buffer(&ms, &mic);
 653                 }
 654         }
 655
 656         return status;
 657 }
 658
 659 void
 660 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 661 {
 662         Authctxt *authctxt = ctxt;
 663         Gssctxt *gssctxt;
 664         int oidlen;
 665         char *oidv;
 666
 667         if (authctxt == NULL)
 668                 fatal("input_gssapi_response: no authentication context");
 669         gssctxt = authctxt->methoddata;
 670
 671         /* Setup our OID */
 672         oidv = packet_get_string(&oidlen);
 673
 674         if (oidlen <= 2 ||
 675             oidv[0] != SSH_GSS_OIDTYPE ||
 676             oidv[1] != oidlen - 2) {
 677                 xfree(oidv);
 678                 debug("Badly encoded mechanism OID received");
 679                 userauth(authctxt, NULL);
 680                 return;
 681         }
 682
 683         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 684                 fatal("Server returned different OID than expected");
 685
 686         packet_check_eom();
 687
 688         xfree(oidv);
 689
 690         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 691                 /* Start again with next method on list */
 692                 debug("Trying to start again");
 693                 userauth(authctxt, NULL);
 694                 return;
 695         }
 696 }
 697
 698 void
 699 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 700 {
 701         Authctxt *authctxt = ctxt;
 702         gss_buffer_desc recv_tok;
 703         OM_uint32 status;
 704         u_int slen;
 705
 706         if (authctxt == NULL)
 707                 fatal("input_gssapi_response: no authentication context");
 708
 709         recv_tok.value = packet_get_string(&slen);
 710         recv_tok.length = slen; /* safe typecast */
 711
 712         packet_check_eom();
 713
 714         status = process_gssapi_token(ctxt, &recv_tok);
 715
 716         xfree(recv_tok.value);
 717
 718         if (GSS_ERROR(status)) {
 719                 /* Start again with the next method in the list */
 720                 userauth(authctxt, NULL);
 721                 return;
 722         }
 723 }
 724
 725 void
 726 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 727 {
 728         Authctxt *authctxt = ctxt;
 729         Gssctxt *gssctxt;
 730         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 731         gss_buffer_desc recv_tok;
 732         OM_uint32 status, ms;
 733         u_int len;
 734
 735         if (authctxt == NULL)
 736                 fatal("input_gssapi_response: no authentication context");
 737         gssctxt = authctxt->methoddata;
 738
 739         recv_tok.value = packet_get_string(&len);
 740         recv_tok.length = len;
 741
 742         packet_check_eom();
 743
 744         /* Stick it into GSSAPI and see what it says */
 745         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 746             &recv_tok, &send_tok, NULL);
 747
 748         xfree(recv_tok.value);
 749         gss_release_buffer(&ms, &send_tok);
 750
 751         /* Server will be returning a failed packet after this one */
 752 }
 753
 754 void
 755 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 756 {
 757         OM_uint32 maj, min;
 758         char *msg;
 759         char *lang;
 760
 761         maj=packet_get_int();
 762         min=packet_get_int();
 763         msg=packet_get_string(NULL);
 764         lang=packet_get_string(NULL);
 765
 766         packet_check_eom();
 767
 768         debug("Server GSSAPI Error:\n%s\n", msg);
 769         xfree(msg);
 770         xfree(lang);
 771 }
 772
 773 int
 774 userauth_external(Authctxt *authctxt)
 775 {
 776         static int attempt = 0;
 777
 778         if (attempt++ >= 1)
 779                 return 0;
 780
 781         /* The client MUST NOT try this method if initial key exchange
 782            was not performed using a GSSAPI-based key exchange
 783            method. */
 784         if (xxx_kex->kex_type != KEX_GSS_GRP1_SHA1) {
 785                 debug2("gsskex not performed, skipping external-keyx");
 786                 return 0;
 787         }
 788
 789         debug2("userauth_external");
 790         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 791 #ifdef GSI
 792         if(options.implicit) {
 793             packet_put_cstring("");
 794         } else {
 795 #endif
 796             packet_put_cstring(authctxt->server_user);
 797 #ifdef GSI
 798         }
 799 #endif
 800         packet_put_cstring(authctxt->service);
 801         packet_put_cstring(authctxt->method->name);
 802         packet_send();
 803         packet_write_wait();
 804         return 1;
 805 }
 806 #endif /* GSSAPI */
 807
 808 int
 809 userauth_none(Authctxt *authctxt)
 810 {
 811         /* initial userauth request */
 812         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 813         packet_put_cstring(authctxt->server_user);
 814         packet_put_cstring(authctxt->service);
 815         packet_put_cstring(authctxt->method->name);
 816         packet_send();
 817         return 1;
 818 }
 819
 820 int
 821 userauth_passwd(Authctxt *authctxt)
 822 {
 823         static int attempt = 0;
 824         char prompt[150];
 825         char *password;
 826
 827         if (attempt++ >= options.number_of_password_prompts)
 828                 return 0;
 829
 830         if (attempt != 1)
 831                 error("Permission denied, please try again.");
 832
 833         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 834             authctxt->server_user, authctxt->host);
 835         password = read_passphrase(prompt, 0);
 836         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 837         packet_put_cstring(authctxt->server_user);
 838         packet_put_cstring(authctxt->service);
 839         packet_put_cstring(authctxt->method->name);
 840         packet_put_char(0);
 841         packet_put_cstring(password);
 842         memset(password, 0, strlen(password));
 843         xfree(password);
 844         packet_add_padding(64);
 845         packet_send();
 846
 847         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 848             &input_userauth_passwd_changereq);
 849
 850         return 1;
 851 }
 852 /*
 853  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 854  */
 855 void
 856 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 857 {
 858         Authctxt *authctxt = ctxt;
 859         char *info, *lang, *password = NULL, *retype = NULL;
 860         char prompt[150];
 861
 862         debug2("input_userauth_passwd_changereq");
 863
 864         if (authctxt == NULL)
 865                 fatal("input_userauth_passwd_changereq: "
 866                     "no authentication context");
 867
 868         info = packet_get_string(NULL);
 869         lang = packet_get_string(NULL);
 870         if (strlen(info) > 0)
 871                 logit("%s", info);
 872         xfree(info);
 873         xfree(lang);
 874         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 875         packet_put_cstring(authctxt->server_user);
 876         packet_put_cstring(authctxt->service);
 877         packet_put_cstring(authctxt->method->name);
 878         packet_put_char(1);                     /* additional info */
 879         snprintf(prompt, sizeof(prompt),
 880             "Enter %.30s@%.128s's old password: ",
 881             authctxt->server_user, authctxt->host);
 882         password = read_passphrase(prompt, 0);
 883         packet_put_cstring(password);
 884         memset(password, 0, strlen(password));
 885         xfree(password);
 886         password = NULL;
 887         while (password == NULL) {
 888                 snprintf(prompt, sizeof(prompt),
 889                     "Enter %.30s@%.128s's new password: ",
 890                     authctxt->server_user, authctxt->host);
 891                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 892                 if (password == NULL) {
 893                         /* bail out */
 894                         return;
 895                 }
 896                 snprintf(prompt, sizeof(prompt),
 897                     "Retype %.30s@%.128s's new password: ",
 898                     authctxt->server_user, authctxt->host);
 899                 retype = read_passphrase(prompt, 0);
 900                 if (strcmp(password, retype) != 0) {
 901                         memset(password, 0, strlen(password));
 902                         xfree(password);
 903                         logit("Mismatch; try again, EOF to quit.");
 904                         password = NULL;
 905                 }
 906                 memset(retype, 0, strlen(retype));
 907                 xfree(retype);
 908         }
 909         packet_put_cstring(password);
 910         memset(password, 0, strlen(password));
 911         xfree(password);
 912         packet_add_padding(64);
 913         packet_send();
 914
 915         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 916             &input_userauth_passwd_changereq);
 917 }
 918
 919 static int
 920 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
 921     u_char *data, u_int datalen)
 922 {
 923         Key *prv;
 924         int ret;
 925
 926         /* the agent supports this key */
 927         if (id->ac)
 928                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
 929                     data, datalen));
 930         /*
 931          * we have already loaded the private key or
 932          * the private key is stored in external hardware
 933          */
 934         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
 935                 return (key_sign(id->key, sigp, lenp, data, datalen));
 936         /* load the private key from the file */
 937         if ((prv = load_identity_file(id->filename)) == NULL)
 938                 return (-1);
 939         ret = key_sign(prv, sigp, lenp, data, datalen);
 940         key_free(prv);
 941         return (ret);
 942 }
 943
 944 static int
 945 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
 946 {
 947         Buffer b;
 948         u_char *blob, *signature;
 949         u_int bloblen, slen;
 950         u_int skip = 0;
 951         int ret = -1;
 952         int have_sig = 1;
 953
 954         debug3("sign_and_send_pubkey");
 955
 956         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
 957                 /* we cannot handle this key */
 958                 debug3("sign_and_send_pubkey: cannot handle key");
 959                 return 0;
 960         }
 961         /* data to be signed */
 962         buffer_init(&b);
 963         if (datafellows & SSH_OLD_SESSIONID) {
 964                 buffer_append(&b, session_id2, session_id2_len);
 965                 skip = session_id2_len;
 966         } else {
 967                 buffer_put_string(&b, session_id2, session_id2_len);
 968                 skip = buffer_len(&b);
 969         }
 970         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
 971         buffer_put_cstring(&b, authctxt->server_user);
 972         buffer_put_cstring(&b,
 973             datafellows & SSH_BUG_PKSERVICE ?
 974             "ssh-userauth" :
 975             authctxt->service);
 976         if (datafellows & SSH_BUG_PKAUTH) {
 977                 buffer_put_char(&b, have_sig);
 978         } else {
 979                 buffer_put_cstring(&b, authctxt->method->name);
 980                 buffer_put_char(&b, have_sig);
 981                 buffer_put_cstring(&b, key_ssh_name(id->key));
 982         }
 983         buffer_put_string(&b, blob, bloblen);
 984
 985         /* generate signature */
 986         ret = identity_sign(id, &signature, &slen,
 987             buffer_ptr(&b), buffer_len(&b));
 988         if (ret == -1) {
 989                 xfree(blob);
 990                 buffer_free(&b);
 991                 return 0;
 992         }
 993 #ifdef DEBUG_PK
 994         buffer_dump(&b);
 995 #endif
 996         if (datafellows & SSH_BUG_PKSERVICE) {
 997                 buffer_clear(&b);
 998                 buffer_append(&b, session_id2, session_id2_len);
 999                 skip = session_id2_len;
1000                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1001                 buffer_put_cstring(&b, authctxt->server_user);
1002                 buffer_put_cstring(&b, authctxt->service);
1003                 buffer_put_cstring(&b, authctxt->method->name);
1004                 buffer_put_char(&b, have_sig);
1005                 if (!(datafellows & SSH_BUG_PKAUTH))
1006                         buffer_put_cstring(&b, key_ssh_name(id->key));
1007                 buffer_put_string(&b, blob, bloblen);
1008         }
1009         xfree(blob);
1010
1011         /* append signature */
1012         buffer_put_string(&b, signature, slen);
1013         xfree(signature);
1014
1015         /* skip session id and packet type */
1016         if (buffer_len(&b) < skip + 1)
1017                 fatal("userauth_pubkey: internal error");
1018         buffer_consume(&b, skip + 1);
1019
1020         /* put remaining data from buffer into packet */
1021         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1022         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1023         buffer_free(&b);
1024         packet_send();
1025
1026         return 1;
1027 }
1028
1029 static int
1030 send_pubkey_test(Authctxt *authctxt, Identity *id)
1031 {
1032         u_char *blob;
1033         u_int bloblen, have_sig = 0;
1034
1035         debug3("send_pubkey_test");
1036
1037         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1038                 /* we cannot handle this key */
1039                 debug3("send_pubkey_test: cannot handle key");
1040                 return 0;
1041         }
1042         /* register callback for USERAUTH_PK_OK message */
1043         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1044
1045         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1046         packet_put_cstring(authctxt->server_user);
1047         packet_put_cstring(authctxt->service);
1048         packet_put_cstring(authctxt->method->name);
1049         packet_put_char(have_sig);
1050         if (!(datafellows & SSH_BUG_PKAUTH))
1051                 packet_put_cstring(key_ssh_name(id->key));
1052         packet_put_string(blob, bloblen);
1053         xfree(blob);
1054         packet_send();
1055         return 1;
1056 }
1057
1058 static Key *
1059 load_identity_file(char *filename)
1060 {
1061         Key *private;
1062         char prompt[300], *passphrase;
1063         int quit, i;
1064         struct stat st;
1065
1066         if (stat(filename, &st) < 0) {
1067                 debug3("no such identity: %s", filename);
1068                 return NULL;
1069         }
1070         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL);
1071         if (private == NULL) {
1072                 if (options.batch_mode)
1073                         return NULL;
1074                 snprintf(prompt, sizeof prompt,
1075                     "Enter passphrase for key '%.100s': ", filename);
1076                 for (i = 0; i < options.number_of_password_prompts; i++) {
1077                         passphrase = read_passphrase(prompt, 0);
1078                         if (strcmp(passphrase, "") != 0) {
1079                                 private = key_load_private_type(KEY_UNSPEC, filename,
1080                                     passphrase, NULL);
1081                                 quit = 0;
1082                         } else {
1083                                 debug2("no passphrase given, try next key");
1084                                 quit = 1;
1085                         }
1086                         memset(passphrase, 0, strlen(passphrase));
1087                         xfree(passphrase);
1088                         if (private != NULL || quit)
1089                                 break;
1090                         debug2("bad passphrase given, try again...");
1091                 }
1092         }
1093         return private;
1094 }
1095
1096 /*
1097  * try keys in the following order:
1098  *      1. agent keys that are found in the config file
1099  *      2. other agent keys
1100  *      3. keys that are only listed in the config file
1101  */
1102 static void
1103 pubkey_prepare(Authctxt *authctxt)
1104 {
1105         Identity *id;
1106         Idlist agent, files, *preferred;
1107         Key *key;
1108         AuthenticationConnection *ac;
1109         char *comment;
1110         int i, found;
1111
1112         TAILQ_INIT(&agent);     /* keys from the agent */
1113         TAILQ_INIT(&files);     /* keys from the config file */
1114         preferred = &authctxt->keys;
1115         TAILQ_INIT(preferred);  /* preferred order of keys */
1116
1117         /* list of keys stored in the filesystem */
1118         for (i = 0; i < options.num_identity_files; i++) {
1119                 key = options.identity_keys[i];
1120                 if (key && key->type == KEY_RSA1)
1121                         continue;
1122                 options.identity_keys[i] = NULL;
1123                 id = xmalloc(sizeof(*id));
1124                 memset(id, 0, sizeof(*id));
1125                 id->key = key;
1126                 id->filename = xstrdup(options.identity_files[i]);
1127                 TAILQ_INSERT_TAIL(&files, id, next);
1128         }
1129         /* list of keys supported by the agent */
1130         if ((ac = ssh_get_authentication_connection())) {
1131                 for (key = ssh_get_first_identity(ac, &comment, 2);
1132                     key != NULL;
1133                     key = ssh_get_next_identity(ac, &comment, 2)) {
1134                         found = 0;
1135                         TAILQ_FOREACH(id, &files, next) {
1136                                 /* agent keys from the config file are preferred */
1137                                 if (key_equal(key, id->key)) {
1138                                         key_free(key);
1139                                         xfree(comment);
1140                                         TAILQ_REMOVE(&files, id, next);
1141                                         TAILQ_INSERT_TAIL(preferred, id, next);
1142                                         id->ac = ac;
1143                                         found = 1;
1144                                         break;
1145                                 }
1146                         }
1147                         if (!found && !options.identities_only) {
1148                                 id = xmalloc(sizeof(*id));
1149                                 memset(id, 0, sizeof(*id));
1150                                 id->key = key;
1151                                 id->filename = comment;
1152                                 id->ac = ac;
1153                                 TAILQ_INSERT_TAIL(&agent, id, next);
1154                         }
1155                 }
1156                 /* append remaining agent keys */
1157                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1158                         TAILQ_REMOVE(&agent, id, next);
1159                         TAILQ_INSERT_TAIL(preferred, id, next);
1160                 }
1161                 authctxt->agent = ac;
1162         }
1163         /* append remaining keys from the config file */
1164         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1165                 TAILQ_REMOVE(&files, id, next);
1166                 TAILQ_INSERT_TAIL(preferred, id, next);
1167         }
1168         TAILQ_FOREACH(id, preferred, next) {
1169                 debug2("key: %s (%p)", id->filename, id->key);
1170         }
1171 }
1172
1173 static void
1174 pubkey_cleanup(Authctxt *authctxt)
1175 {
1176         Identity *id;
1177
1178         if (authctxt->agent != NULL)
1179                 ssh_close_authentication_connection(authctxt->agent);
1180         for (id = TAILQ_FIRST(&authctxt->keys); id;
1181             id = TAILQ_FIRST(&authctxt->keys)) {
1182                 TAILQ_REMOVE(&authctxt->keys, id, next);
1183                 if (id->key)
1184                         key_free(id->key);
1185                 if (id->filename)
1186                         xfree(id->filename);
1187                 xfree(id);
1188         }
1189 }
1190
1191 int
1192 userauth_pubkey(Authctxt *authctxt)
1193 {
1194         Identity *id;
1195         int sent = 0;
1196
1197         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1198                 if (id->tried++)
1199                         return (0);
1200                 /* move key to the end of the queue */
1201                 TAILQ_REMOVE(&authctxt->keys, id, next);
1202                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1203                 /*
1204                  * send a test message if we have the public key. for
1205                  * encrypted keys we cannot do this and have to load the
1206                  * private key instead
1207                  */
1208                 if (id->key && id->key->type != KEY_RSA1) {
1209                         debug("Offering public key: %s", id->filename);
1210                         sent = send_pubkey_test(authctxt, id);
1211                 } else if (id->key == NULL) {
1212                         debug("Trying private key: %s", id->filename);
1213                         id->key = load_identity_file(id->filename);
1214                         if (id->key != NULL) {
1215                                 id->isprivate = 1;
1216                                 sent = sign_and_send_pubkey(authctxt, id);
1217                                 key_free(id->key);
1218                                 id->key = NULL;
1219                         }
1220                 }
1221                 if (sent)
1222                         return (sent);
1223         }
1224         return (0);
1225 }
1226
1227 /*
1228  * Send userauth request message specifying keyboard-interactive method.
1229  */
1230 int
1231 userauth_kbdint(Authctxt *authctxt)
1232 {
1233         static int attempt = 0;
1234
1235         if (attempt++ >= options.number_of_password_prompts)
1236                 return 0;
1237         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1238         if (attempt > 1 && !authctxt->info_req_seen) {
1239                 debug3("userauth_kbdint: disable: no info_req_seen");
1240                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1241                 return 0;
1242         }
1243
1244         debug2("userauth_kbdint");
1245         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1246         packet_put_cstring(authctxt->server_user);
1247         packet_put_cstring(authctxt->service);
1248         packet_put_cstring(authctxt->method->name);
1249         packet_put_cstring("");                                 /* lang */
1250         packet_put_cstring(options.kbd_interactive_devices ?
1251             options.kbd_interactive_devices : "");
1252         packet_send();
1253
1254         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1255         return 1;
1256 }
1257
1258 /*
1259  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1260  */
1261 void
1262 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1263 {
1264         Authctxt *authctxt = ctxt;
1265         char *name, *inst, *lang, *prompt, *response;
1266         u_int num_prompts, i;
1267         int echo = 0;
1268
1269         debug2("input_userauth_info_req");
1270
1271         if (authctxt == NULL)
1272                 fatal("input_userauth_info_req: no authentication context");
1273
1274         authctxt->info_req_seen = 1;
1275
1276         name = packet_get_string(NULL);
1277         inst = packet_get_string(NULL);
1278         lang = packet_get_string(NULL);
1279         if (strlen(name) > 0)
1280                 logit("%s", name);
1281         if (strlen(inst) > 0)
1282                 logit("%s", inst);
1283         xfree(name);
1284         xfree(inst);
1285         xfree(lang);
1286
1287         num_prompts = packet_get_int();
1288         /*
1289          * Begin to build info response packet based on prompts requested.
1290          * We commit to providing the correct number of responses, so if
1291          * further on we run into a problem that prevents this, we have to
1292          * be sure and clean this up and send a correct error response.
1293          */
1294         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1295         packet_put_int(num_prompts);
1296
1297         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1298         for (i = 0; i < num_prompts; i++) {
1299                 prompt = packet_get_string(NULL);
1300                 echo = packet_get_char();
1301
1302                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1303
1304                 packet_put_cstring(response);
1305                 memset(response, 0, strlen(response));
1306                 xfree(response);
1307                 xfree(prompt);
1308         }
1309         packet_check_eom(); /* done with parsing incoming message. */
1310
1311         packet_add_padding(64);
1312         packet_send();
1313 }
1314
1315 static int
1316 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1317     u_char *data, u_int datalen)
1318 {
1319         Buffer b;
1320         struct stat st;
1321         pid_t pid;
1322         int to[2], from[2], status, version = 2;
1323
1324         debug2("ssh_keysign called");
1325
1326         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1327                 error("ssh_keysign: no installed: %s", strerror(errno));
1328                 return -1;
1329         }
1330         if (fflush(stdout) != 0)
1331                 error("ssh_keysign: fflush: %s", strerror(errno));
1332         if (pipe(to) < 0) {
1333                 error("ssh_keysign: pipe: %s", strerror(errno));
1334                 return -1;
1335         }
1336         if (pipe(from) < 0) {
1337                 error("ssh_keysign: pipe: %s", strerror(errno));
1338                 return -1;
1339         }
1340         if ((pid = fork()) < 0) {
1341                 error("ssh_keysign: fork: %s", strerror(errno));
1342                 return -1;
1343         }
1344         if (pid == 0) {
1345                 seteuid(getuid());
1346                 setuid(getuid());
1347                 close(from[0]);
1348                 if (dup2(from[1], STDOUT_FILENO) < 0)
1349                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1350                 close(to[1]);
1351                 if (dup2(to[0], STDIN_FILENO) < 0)
1352                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1353                 close(from[1]);
1354                 close(to[0]);
1355                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1356                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1357                     strerror(errno));
1358         }
1359         close(from[1]);
1360         close(to[0]);
1361
1362         buffer_init(&b);
1363         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1364         buffer_put_string(&b, data, datalen);
1365         if (ssh_msg_send(to[1], version, &b) == -1)
1366                 fatal("ssh_keysign: couldn't send request");
1367
1368         if (ssh_msg_recv(from[0], &b) < 0) {
1369                 error("ssh_keysign: no reply");
1370                 buffer_free(&b);
1371                 return -1;
1372         }
1373         close(from[0]);
1374         close(to[1]);
1375
1376         while (waitpid(pid, &status, 0) < 0)
1377                 if (errno != EINTR)
1378                         break;
1379
1380         if (buffer_get_char(&b) != version) {
1381                 error("ssh_keysign: bad version");
1382                 buffer_free(&b);
1383                 return -1;
1384         }
1385         *sigp = buffer_get_string(&b, lenp);
1386         buffer_free(&b);
1387
1388         return 0;
1389 }
1390
1391 int
1392 userauth_hostbased(Authctxt *authctxt)
1393 {
1394         Key *private = NULL;
1395         Sensitive *sensitive = authctxt->sensitive;
1396         Buffer b;
1397         u_char *signature, *blob;
1398         char *chost, *pkalg, *p;
1399         const char *service;
1400         u_int blen, slen;
1401         int ok, i, len, found = 0;
1402
1403         /* check for a useful key */
1404         for (i = 0; i < sensitive->nkeys; i++) {
1405                 private = sensitive->keys[i];
1406                 if (private && private->type != KEY_RSA1) {
1407                         found = 1;
1408                         /* we take and free the key */
1409                         sensitive->keys[i] = NULL;
1410                         break;
1411                 }
1412         }
1413         if (!found) {
1414                 debug("No more client hostkeys for hostbased authentication.");
1415                 return 0;
1416         }
1417         if (key_to_blob(private, &blob, &blen) == 0) {
1418                 key_free(private);
1419                 return 0;
1420         }
1421         /* figure out a name for the client host */
1422         p = get_local_name(packet_get_connection_in());
1423         if (p == NULL) {
1424                 error("userauth_hostbased: cannot get local ipaddr/name");
1425                 key_free(private);
1426                 return 0;
1427         }
1428         len = strlen(p) + 2;
1429         chost = xmalloc(len);
1430         strlcpy(chost, p, len);
1431         strlcat(chost, ".", len);
1432         debug2("userauth_hostbased: chost %s", chost);
1433         xfree(p);
1434
1435         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1436             authctxt->service;
1437         pkalg = xstrdup(key_ssh_name(private));
1438         buffer_init(&b);
1439         /* construct data */
1440         buffer_put_string(&b, session_id2, session_id2_len);
1441         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1442         buffer_put_cstring(&b, authctxt->server_user);
1443         buffer_put_cstring(&b, service);
1444         buffer_put_cstring(&b, authctxt->method->name);
1445         buffer_put_cstring(&b, pkalg);
1446         buffer_put_string(&b, blob, blen);
1447         buffer_put_cstring(&b, chost);
1448         buffer_put_cstring(&b, authctxt->local_user);
1449 #ifdef DEBUG_PK
1450         buffer_dump(&b);
1451 #endif
1452         if (sensitive->external_keysign)
1453                 ok = ssh_keysign(private, &signature, &slen,
1454                     buffer_ptr(&b), buffer_len(&b));
1455         else
1456                 ok = key_sign(private, &signature, &slen,
1457                     buffer_ptr(&b), buffer_len(&b));
1458         key_free(private);
1459         buffer_free(&b);
1460         if (ok != 0) {
1461                 error("key_sign failed");
1462                 xfree(chost);
1463                 xfree(pkalg);
1464                 return 0;
1465         }
1466         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1467         packet_put_cstring(authctxt->server_user);
1468         packet_put_cstring(authctxt->service);
1469         packet_put_cstring(authctxt->method->name);
1470         packet_put_cstring(pkalg);
1471         packet_put_string(blob, blen);
1472         packet_put_cstring(chost);
1473         packet_put_cstring(authctxt->local_user);
1474         packet_put_string(signature, slen);
1475         memset(signature, 's', slen);
1476         xfree(signature);
1477         xfree(chost);
1478         xfree(pkalg);
1479
1480         packet_send();
1481         return 1;
1482 }
1483
1484 /* find auth method */
1485
1486 /*
1487  * given auth method name, if configurable options permit this method fill
1488  * in auth_ident field and return true, otherwise return false.
1489  */
1490 static int
1491 authmethod_is_enabled(Authmethod *method)
1492 {
1493         if (method == NULL)
1494                 return 0;
1495         /* return false if options indicate this method is disabled */
1496         if  (method->enabled == NULL || *method->enabled == 0)
1497                 return 0;
1498         /* return false if batch mode is enabled but method needs interactive mode */
1499         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1500                 return 0;
1501         return 1;
1502 }
1503
1504 static Authmethod *
1505 authmethod_lookup(const char *name)
1506 {
1507         Authmethod *method = NULL;
1508         if (name != NULL)
1509                 for (method = authmethods; method->name != NULL; method++)
1510                         if (strcmp(name, method->name) == 0)
1511                                 return method;
1512         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1513         return NULL;
1514 }
1515
1516 /* XXX internal state */
1517 static Authmethod *current = NULL;
1518 static char *supported = NULL;
1519 static char *preferred = NULL;
1520
1521 /*
1522  * Given the authentication method list sent by the server, return the
1523  * next method we should try.  If the server initially sends a nil list,
1524  * use a built-in default list.
1525  */
1526 static Authmethod *
1527 authmethod_get(char *authlist)
1528 {
1529         char *name = NULL;
1530         u_int next;
1531
1532         /* Use a suitable default if we're passed a nil list.  */
1533         if (authlist == NULL || strlen(authlist) == 0)
1534                 authlist = options.preferred_authentications;
1535
1536         if (supported == NULL || strcmp(authlist, supported) != 0) {
1537                 debug3("start over, passed a different list %s", authlist);
1538                 if (supported != NULL)
1539                         xfree(supported);
1540                 supported = xstrdup(authlist);
1541                 preferred = options.preferred_authentications;
1542                 debug3("preferred %s", preferred);
1543                 current = NULL;
1544         } else if (current != NULL && authmethod_is_enabled(current))
1545                 return current;
1546
1547         for (;;) {
1548                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1549                         debug("No more authentication methods to try.");
1550                         current = NULL;
1551                         return NULL;
1552                 }
1553                 preferred += next;
1554                 debug3("authmethod_lookup %s", name);
1555                 debug3("remaining preferred: %s", preferred);
1556                 if ((current = authmethod_lookup(name)) != NULL &&
1557                     authmethod_is_enabled(current)) {
1558                         debug3("authmethod_is_enabled %s", name);
1559                         debug("Next authentication method: %s", name);
1560                         return current;
1561                 }
1562         }
1563 }
1564
1565 static char *
1566 authmethods_get(void)
1567 {
1568         Authmethod *method = NULL;
1569         Buffer b;
1570         char *list;
1571
1572         buffer_init(&b);
1573         for (method = authmethods; method->name != NULL; method++) {
1574                 if (authmethod_is_enabled(method)) {
1575                         if (buffer_len(&b) > 0)
1576                                 buffer_append(&b, ",", 1);
1577                         buffer_append(&b, method->name, strlen(method->name));
1578                 }
1579         }
1580         buffer_append(&b, "\0", 1);
1581         list = xstrdup(buffer_ptr(&b));
1582         buffer_free(&b);
1583         return list;
1584 }