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 1.124 2003/08/25 10:33:33 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 "readpass.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, *gss;
  88         int len;
  89 #endif
  90
  91         xxx_host = host;
  92         xxx_hostaddr = hostaddr;
  93
  94 #ifdef GSSAPI
  95         if (options.gss_keyex) {
  96         char *canonhost;
  97         /* Add the GSSAPI mechanisms currently supported on this client to
  98          * the key exchange algorithm proposal */
  99         orig = myproposal[PROPOSAL_KEX_ALGS];
 100         canonhost = xstrdup(get_canonical_hostname(1));
 101         resolve_localhost(&canonhost);
 102         gss = ssh_gssapi_client_mechanisms(canonhost);
 103         xfree(canonhost);
 104         canonhost=NULL;
 105         if (gss) {
 106            len = strlen(orig)+strlen(gss)+2;
 107            myproposal[PROPOSAL_KEX_ALGS]=xmalloc(len);
 108            snprintf(myproposal[PROPOSAL_KEX_ALGS],len,"%s,%s",gss,orig);
 109         }
 110         }
 111 #endif
 112
 113         if (options.ciphers == (char *)-1) {
 114                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 115                 options.ciphers = NULL;
 116         }
 117         if (options.ciphers != NULL) {
 118                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 119                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 120         }
 121         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 122             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 123         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 124             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 125         if (options.compression) {
 126                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 127                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib,none";
 128         } else {
 129                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 130                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib";
 131         }
 132         if (options.macs != NULL) {
 133                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 134                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 135         }
 136         if (options.hostkeyalgorithms != NULL)
 137                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 138                     options.hostkeyalgorithms;
 139
 140 #ifdef GSSAPI
 141         /* If we've got GSSAPI algorithms, then we also support the
 142          * 'null' hostkey, as a last resort */
 143         if (options.gss_keyex && gss) {
 144                 orig=myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
 145                 len = strlen(orig)+sizeof(",null");
 146                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]=xmalloc(len);
 147                 snprintf(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS],len,"%s,null",orig);
 148         }
 149 #endif
 150
 151         if (options.rekey_limit)
 152                 packet_set_rekey_limit(options.rekey_limit);
 153
 154         /* start key exchange */
 155         kex = kex_setup(myproposal);
 156         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 157         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 158 #ifdef GSSAPI
 159         kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client;
 160 #endif
 161         kex->client_version_string=client_version_string;
 162         kex->server_version_string=server_version_string;
 163         kex->verify_host_key=&verify_host_key_callback;
 164 #ifdef GSSAPI
 165         kex->options.gss_deleg_creds=options.gss_deleg_creds;
 166 #endif
 167
 168         xxx_kex = kex;
 169
 170         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 171
 172         session_id2 = kex->session_id;
 173         session_id2_len = kex->session_id_len;
 174
 175 #ifdef DEBUG_KEXDH
 176         /* send 1st encrypted/maced/compressed message */
 177         packet_start(SSH2_MSG_IGNORE);
 178         packet_put_cstring("markus");
 179         packet_send();
 180         packet_write_wait();
 181 #endif
 182 }
 183
 184 /*
 185  * Authenticate user
 186  */
 187
 188 typedef struct Authctxt Authctxt;
 189 typedef struct Authmethod Authmethod;
 190 typedef struct identity Identity;
 191 typedef struct idlist Idlist;
 192
 193 struct identity {
 194         TAILQ_ENTRY(identity) next;
 195         AuthenticationConnection *ac;   /* set if agent supports key */
 196         Key     *key;                   /* public/private key */
 197         char    *filename;              /* comment for agent-only keys */
 198         int     tried;
 199         int     isprivate;              /* key points to the private key */
 200 };
 201 TAILQ_HEAD(idlist, identity);
 202
 203 struct Authctxt {
 204         const char *server_user;
 205         const char *local_user;
 206         const char *host;
 207         const char *service;
 208         Authmethod *method;
 209         int success;
 210         char *authlist;
 211         /* pubkey */
 212         Idlist keys;
 213         AuthenticationConnection *agent;
 214         /* hostbased */
 215         Sensitive *sensitive;
 216         /* kbd-interactive */
 217         int info_req_seen;
 218         /* generic */
 219         void *methoddata;
 220 };
 221 struct Authmethod {
 222         char    *name;          /* string to compare against server's list */
 223         int     (*userauth)(Authctxt *authctxt);
 224         int     *enabled;       /* flag in option struct that enables method */
 225         int     *batch_flag;    /* flag in option struct that disables method */
 226 };
 227
 228 void    input_userauth_success(int, u_int32_t, void *);
 229 void    input_userauth_failure(int, u_int32_t, void *);
 230 void    input_userauth_banner(int, u_int32_t, void *);
 231 void    input_userauth_error(int, u_int32_t, void *);
 232 void    input_userauth_info_req(int, u_int32_t, void *);
 233 void    input_userauth_pk_ok(int, u_int32_t, void *);
 234 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 235
 236 int     userauth_none(Authctxt *);
 237 int     userauth_pubkey(Authctxt *);
 238 int     userauth_passwd(Authctxt *);
 239 int     userauth_kbdint(Authctxt *);
 240 int     userauth_hostbased(Authctxt *);
 241 int     userauth_kerberos(Authctxt *);
 242
 243 #ifdef GSSAPI
 244 int     userauth_gssapi(Authctxt *authctxt);
 245 void    input_gssapi_response(int type, u_int32_t, void *);
 246 void    input_gssapi_token(int type, u_int32_t, void *);
 247 void    input_gssapi_hash(int type, u_int32_t, void *);
 248 void    input_gssapi_error(int, u_int32_t, void *);
 249 void    input_gssapi_errtok(int, u_int32_t, void *);
 250 #endif
 251
 252 #ifdef GSSAPI
 253 int     userauth_external(Authctxt *authctxt);
 254 int     userauth_gssapi(Authctxt *authctxt);
 255 void    input_gssapi_response(int type, u_int32_t, void *);
 256 void    input_gssapi_token(int type, u_int32_t, void *);
 257 void    input_gssapi_hash(int type, u_int32_t, void *);
 258 void    input_gssapi_error(int, u_int32_t, void *);
 259 void    input_gssapi_errtok(int, u_int32_t, void *);
 260 #endif
 261
 262 void    userauth(Authctxt *, char *);
 263
 264 static int sign_and_send_pubkey(Authctxt *, Identity *);
 265 static void pubkey_prepare(Authctxt *);
 266 static void pubkey_cleanup(Authctxt *);
 267 static Key *load_identity_file(char *);
 268
 269 static Authmethod *authmethod_get(char *authlist);
 270 static Authmethod *authmethod_lookup(const char *name);
 271 static char *authmethods_get(void);
 272
 273 Authmethod authmethods[] = {
 274 #ifdef GSSAPI
 275         {"external-keyx",
 276                 userauth_external,
 277                 &options.gss_authentication,
 278                 NULL},
 279         {"gssapi",
 280                 userauth_gssapi,
 281                 &options.gss_authentication,
 282                 NULL},
 283 #endif
 284         {"hostbased",
 285                 userauth_hostbased,
 286                 &options.hostbased_authentication,
 287                 NULL},
 288         {"publickey",
 289                 userauth_pubkey,
 290                 &options.pubkey_authentication,
 291                 NULL},
 292         {"keyboard-interactive",
 293                 userauth_kbdint,
 294                 &options.kbd_interactive_authentication,
 295                 &options.batch_mode},
 296         {"password",
 297                 userauth_passwd,
 298                 &options.password_authentication,
 299                 &options.batch_mode},
 300         {"none",
 301                 userauth_none,
 302                 NULL,
 303                 NULL},
 304         {NULL, NULL, NULL, NULL}
 305 };
 306
 307 void
 308 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 309     Sensitive *sensitive)
 310 {
 311         Authctxt authctxt;
 312         int type;
 313
 314         if (options.challenge_response_authentication)
 315                 options.kbd_interactive_authentication = 1;
 316
 317         packet_start(SSH2_MSG_SERVICE_REQUEST);
 318         packet_put_cstring("ssh-userauth");
 319         packet_send();
 320         debug("SSH2_MSG_SERVICE_REQUEST sent");
 321         packet_write_wait();
 322         type = packet_read();
 323         if (type != SSH2_MSG_SERVICE_ACCEPT)
 324                 fatal("Server denied authentication request: %d", type);
 325         if (packet_remaining() > 0) {
 326                 char *reply = packet_get_string(NULL);
 327                 debug2("service_accept: %s", reply);
 328                 xfree(reply);
 329         } else {
 330                 debug2("buggy server: service_accept w/o service");
 331         }
 332         packet_check_eom();
 333         debug("SSH2_MSG_SERVICE_ACCEPT received");
 334
 335         if (options.preferred_authentications == NULL)
 336                 options.preferred_authentications = authmethods_get();
 337
 338         /* setup authentication context */
 339         memset(&authctxt, 0, sizeof(authctxt));
 340         pubkey_prepare(&authctxt);
 341         authctxt.server_user = server_user;
 342         authctxt.local_user = local_user;
 343         authctxt.host = host;
 344         authctxt.service = "ssh-connection";            /* service name */
 345         authctxt.success = 0;
 346         authctxt.method = authmethod_lookup("none");
 347         authctxt.authlist = NULL;
 348         authctxt.methoddata = NULL;
 349         authctxt.sensitive = sensitive;
 350         authctxt.info_req_seen = 0;
 351         if (authctxt.method == NULL)
 352                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 353
 354         /* initial userauth request */
 355         userauth_none(&authctxt);
 356
 357         dispatch_init(&input_userauth_error);
 358         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 359         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 360         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 361         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 362
 363         pubkey_cleanup(&authctxt);
 364         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 365
 366         debug("Authentication succeeded (%s).", authctxt.method->name);
 367 }
 368
 369 void
 370 userauth(Authctxt *authctxt, char *authlist)
 371 {
 372         if (authctxt->methoddata) {
 373                 xfree(authctxt->methoddata);
 374                 authctxt->methoddata = NULL;
 375         }
 376         if (authlist == NULL) {
 377                 authlist = authctxt->authlist;
 378         } else {
 379                 if (authctxt->authlist)
 380                         xfree(authctxt->authlist);
 381                 authctxt->authlist = authlist;
 382         }
 383         for (;;) {
 384                 Authmethod *method = authmethod_get(authlist);
 385                 if (method == NULL)
 386                         fatal("Permission denied (%s).", authlist);
 387                 authctxt->method = method;
 388
 389                 /* reset the per method handler */
 390                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 391                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 392
 393                 /* and try new method */
 394                 if (method->userauth(authctxt) != 0) {
 395                         debug2("we sent a %s packet, wait for reply", method->name);
 396                         break;
 397                 } else {
 398                         debug2("we did not send a packet, disable method");
 399                         method->enabled = NULL;
 400                 }
 401         }
 402 }
 403
 404 void
 405 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 406 {
 407         fatal("input_userauth_error: bad message during authentication: "
 408            "type %d", type);
 409 }
 410
 411 void
 412 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 413 {
 414         char *msg, *lang;
 415         debug3("input_userauth_banner");
 416         msg = packet_get_string(NULL);
 417         lang = packet_get_string(NULL);
 418         logit("%s", msg);
 419         xfree(msg);
 420         xfree(lang);
 421 }
 422
 423 void
 424 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 425 {
 426         Authctxt *authctxt = ctxt;
 427         if (authctxt == NULL)
 428                 fatal("input_userauth_success: no authentication context");
 429         if (authctxt->authlist)
 430                 xfree(authctxt->authlist);
 431         if (authctxt->methoddata)
 432                 xfree(authctxt->methoddata);
 433         authctxt->success = 1;                  /* break out */
 434 }
 435
 436 void
 437 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 438 {
 439         Authctxt *authctxt = ctxt;
 440         char *authlist = NULL;
 441         int partial;
 442
 443         if (authctxt == NULL)
 444                 fatal("input_userauth_failure: no authentication context");
 445
 446         authlist = packet_get_string(NULL);
 447         partial = packet_get_char();
 448         packet_check_eom();
 449
 450         if (partial != 0)
 451                 logit("Authenticated with partial success.");
 452         debug("Authentications that can continue: %s", authlist);
 453
 454         userauth(authctxt, authlist);
 455 }
 456 void
 457 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 458 {
 459         Authctxt *authctxt = ctxt;
 460         Key *key = NULL;
 461         Identity *id = NULL;
 462         Buffer b;
 463         int pktype, sent = 0;
 464         u_int alen, blen;
 465         char *pkalg, *fp;
 466         u_char *pkblob;
 467
 468         if (authctxt == NULL)
 469                 fatal("input_userauth_pk_ok: no authentication context");
 470         if (datafellows & SSH_BUG_PKOK) {
 471                 /* this is similar to SSH_BUG_PKAUTH */
 472                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 473                 pkblob = packet_get_string(&blen);
 474                 buffer_init(&b);
 475                 buffer_append(&b, pkblob, blen);
 476                 pkalg = buffer_get_string(&b, &alen);
 477                 buffer_free(&b);
 478         } else {
 479                 pkalg = packet_get_string(&alen);
 480                 pkblob = packet_get_string(&blen);
 481         }
 482         packet_check_eom();
 483
 484         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 485
 486         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 487                 debug("unknown pkalg %s", pkalg);
 488                 goto done;
 489         }
 490         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 491                 debug("no key from blob. pkalg %s", pkalg);
 492                 goto done;
 493         }
 494         if (key->type != pktype) {
 495                 error("input_userauth_pk_ok: type mismatch "
 496                     "for decoded key (received %d, expected %d)",
 497                     key->type, pktype);
 498                 goto done;
 499         }
 500         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 501         debug2("input_userauth_pk_ok: fp %s", fp);
 502         xfree(fp);
 503
 504         TAILQ_FOREACH(id, &authctxt->keys, next) {
 505                 if (key_equal(key, id->key)) {
 506                         sent = sign_and_send_pubkey(authctxt, id);
 507                         break;
 508                 }
 509         }
 510 done:
 511         if (key != NULL)
 512                 key_free(key);
 513         xfree(pkalg);
 514         xfree(pkblob);
 515
 516         /* try another method if we did not send a packet */
 517         if (sent == 0)
 518                 userauth(authctxt, NULL);
 519 }
 520
 521 #ifdef GSSAPI
 522 int
 523 userauth_gssapi(Authctxt *authctxt)
 524 {
 525         Gssctxt *gssctxt = NULL;
 526         static gss_OID_set supported = NULL;
 527         static int mech = 0;
 528         OM_uint32 min;
 529         int ok = 0;
 530
 531         if (!options.gss_authentication) {
 532                 verbose("GSSAPI authentication disabled.");
 533                 return 0;
 534         }
 535
 536         /* Try one GSSAPI method at a time, rather than sending them all at
 537          * once. */
 538
 539         if (supported == NULL)
 540                 gss_indicate_mechs(&min, &supported);
 541
 542         /* Check to see if the mechanism is usable before we offer it */
 543         while (mech<supported->count && !ok) {
 544                 if (gssctxt)
 545                         ssh_gssapi_delete_ctx(&gssctxt);
 546                 ssh_gssapi_build_ctx(&gssctxt);
 547                 ssh_gssapi_set_oid(gssctxt, &supported->elements[mech]);
 548
 549                 /* My DER encoding requires length<128 */
 550                 if (supported->elements[mech].length < 128 &&
 551                     !GSS_ERROR(ssh_gssapi_import_name(gssctxt,
 552                     authctxt->host))) {
 553                         ok = 1; /* Mechanism works */
 554                 } else {
 555                         mech++;
 556                 }
 557         }
 558
 559         if (!ok) return 0;
 560
 561         authctxt->methoddata=(void *)gssctxt;
 562
 563         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 564         packet_put_cstring(authctxt->server_user);
 565         packet_put_cstring(authctxt->service);
 566         packet_put_cstring(authctxt->method->name);
 567
 568         packet_put_int(1);
 569
 570         /* Some servers encode the OID incorrectly (as we used to) */
 571         if (datafellows & SSH_BUG_GSSAPI_BER) {
 572                 packet_put_string(supported->elements[mech].elements,
 573                     supported->elements[mech].length);
 574         } else {
 575                 packet_put_int((supported->elements[mech].length)+2);
 576                 packet_put_char(SSH_GSS_OIDTYPE);
 577                 packet_put_char(supported->elements[mech].length);
 578                 packet_put_raw(supported->elements[mech].elements,
 579                     supported->elements[mech].length);
 580         }
 581
 582         packet_send();
 583
 584         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 585         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 586         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 587         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 588
 589         mech++; /* Move along to next candidate */
 590
 591         return 1;
 592 }
 593
 594 void
 595 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 596 {
 597         Authctxt *authctxt = ctxt;
 598         Gssctxt *gssctxt;
 599         OM_uint32 status, ms;
 600         int oidlen;
 601         char *oidv;
 602         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 603
 604         if (authctxt == NULL)
 605                 fatal("input_gssapi_response: no authentication context");
 606         gssctxt = authctxt->methoddata;
 607
 608         /* Setup our OID */
 609         oidv = packet_get_string(&oidlen);
 610
 611         if (datafellows & SSH_BUG_GSSAPI_BER) {
 612                 if (!ssh_gssapi_check_oid(gssctxt, oidv, oidlen))
 613                         fatal("Server returned different OID than expected");
 614         } else {
 615                 if(oidv[0] != SSH_GSS_OIDTYPE || oidv[1] != oidlen-2) {
 616                         debug("Badly encoded mechanism OID received");
 617                         userauth(authctxt, NULL);
 618                         xfree(oidv);
 619                         return;
 620                 }
 621                 if (!ssh_gssapi_check_oid(gssctxt, oidv+2, oidlen-2))
 622                         fatal("Server returned different OID than expected");
 623         }
 624
 625         packet_check_eom();
 626
 627         xfree(oidv);
 628
 629         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 630             GSS_C_NO_BUFFER, &send_tok, NULL);
 631         if (GSS_ERROR(status)) {
 632                 if (send_tok.length > 0) {
 633                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 634                         packet_put_string(send_tok.value, send_tok.length);
 635                         packet_send();
 636                         gss_release_buffer(&ms, &send_tok);
 637                 }
 638                 /* Start again with next method on list */
 639                 debug("Trying to start again");
 640                 userauth(authctxt, NULL);
 641                 return;
 642         }
 643
 644         /* We must have data to send */
 645         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 646         packet_put_string(send_tok.value, send_tok.length);
 647         packet_send();
 648         gss_release_buffer(&ms, &send_tok);
 649 }
 650
 651 void
 652 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 653 {
 654         Authctxt *authctxt = ctxt;
 655         Gssctxt *gssctxt;
 656         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 657         gss_buffer_desc recv_tok;
 658         OM_uint32 status, ms;
 659         u_int slen;
 660
 661         if (authctxt == NULL)
 662                 fatal("input_gssapi_response: no authentication context");
 663         gssctxt = authctxt->methoddata;
 664
 665         recv_tok.value = packet_get_string(&slen);
 666         recv_tok.length = slen; /* safe typecast */
 667
 668         packet_check_eom();
 669
 670         status=ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 671             &recv_tok, &send_tok, NULL);
 672
 673         xfree(recv_tok.value);
 674
 675         if (GSS_ERROR(status)) {
 676                 if (send_tok.length > 0) {
 677                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 678                         packet_put_string(send_tok.value, send_tok.length);
 679                         packet_send();
 680                         gss_release_buffer(&ms, &send_tok);
 681                 }
 682                 /* Start again with the next method in the list */
 683                 userauth(authctxt, NULL);
 684                 return;
 685         }
 686
 687         if (send_tok.length > 0) {
 688                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 689                 packet_put_string(send_tok.value, send_tok.length);
 690                 packet_send();
 691                 gss_release_buffer(&ms, &send_tok);
 692         }
 693
 694         if (status == GSS_S_COMPLETE) {
 695                 /* If that succeeded, send a exchange complete message */
 696                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 697                 packet_send();
 698         }
 699 }
 700
 701 void
 702 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 703 {
 704         Authctxt *authctxt = ctxt;
 705         Gssctxt *gssctxt;
 706         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 707         gss_buffer_desc recv_tok;
 708         OM_uint32 status, ms;
 709         u_int len;
 710
 711         if (authctxt == NULL)
 712                 fatal("input_gssapi_response: no authentication context");
 713         gssctxt = authctxt->methoddata;
 714
 715         recv_tok.value = packet_get_string(&len);
 716         recv_tok.length = len;
 717
 718         packet_check_eom();
 719
 720         /* Stick it into GSSAPI and see what it says */
 721         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 722                                      &recv_tok, &send_tok, NULL);
 723
 724         xfree(recv_tok.value);
 725         gss_release_buffer(&ms, &send_tok);
 726
 727         /* Server will be returning a failed packet after this one */
 728 }
 729
 730 void
 731 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 732 {
 733         OM_uint32 maj, min;
 734         char *msg;
 735         char *lang;
 736
 737         maj=packet_get_int();
 738         min=packet_get_int();
 739         msg=packet_get_string(NULL);
 740         lang=packet_get_string(NULL);
 741
 742         packet_check_eom();
 743
 744         debug("Server GSSAPI Error:\n%s\n", msg);
 745         xfree(msg);
 746         xfree(lang);
 747 }
 748
 749 int
 750 userauth_external(Authctxt *authctxt)
 751 {
 752         static int attempt = 0;
 753
 754         if (attempt++ >= 1)
 755                 return 0;
 756
 757         debug2("userauth_external");
 758         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 759 #ifdef GSI
 760         if(options.implicit && !(datafellows & SSH_BUG_GSS_EMPTYUSER)) {
 761             packet_put_cstring("");
 762         } else {
 763 #endif
 764             packet_put_cstring(authctxt->server_user);
 765 #ifdef GSI
 766         }
 767 #endif
 768         packet_put_cstring(authctxt->service);
 769         packet_put_cstring(authctxt->method->name);
 770         packet_send();
 771         packet_write_wait();
 772         return 1;
 773 }
 774 #endif /* GSSAPI */
 775
 776 int
 777 userauth_none(Authctxt *authctxt)
 778 {
 779         /* initial userauth request */
 780         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 781         packet_put_cstring(authctxt->server_user);
 782         packet_put_cstring(authctxt->service);
 783         packet_put_cstring(authctxt->method->name);
 784         packet_send();
 785         return 1;
 786 }
 787
 788 int
 789 userauth_passwd(Authctxt *authctxt)
 790 {
 791         static int attempt = 0;
 792         char prompt[150];
 793         char *password;
 794
 795         if (attempt++ >= options.number_of_password_prompts)
 796                 return 0;
 797
 798         if (attempt != 1)
 799                 error("Permission denied, please try again.");
 800
 801         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 802             authctxt->server_user, authctxt->host);
 803         password = read_passphrase(prompt, 0);
 804         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 805         packet_put_cstring(authctxt->server_user);
 806         packet_put_cstring(authctxt->service);
 807         packet_put_cstring(authctxt->method->name);
 808         packet_put_char(0);
 809         packet_put_cstring(password);
 810         memset(password, 0, strlen(password));
 811         xfree(password);
 812         packet_add_padding(64);
 813         packet_send();
 814
 815         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 816             &input_userauth_passwd_changereq);
 817
 818         return 1;
 819 }
 820 /*
 821  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 822  */
 823 void
 824 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 825 {
 826         Authctxt *authctxt = ctxt;
 827         char *info, *lang, *password = NULL, *retype = NULL;
 828         char prompt[150];
 829
 830         debug2("input_userauth_passwd_changereq");
 831
 832         if (authctxt == NULL)
 833                 fatal("input_userauth_passwd_changereq: "
 834                     "no authentication context");
 835
 836         info = packet_get_string(NULL);
 837         lang = packet_get_string(NULL);
 838         if (strlen(info) > 0)
 839                 logit("%s", info);
 840         xfree(info);
 841         xfree(lang);
 842         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 843         packet_put_cstring(authctxt->server_user);
 844         packet_put_cstring(authctxt->service);
 845         packet_put_cstring(authctxt->method->name);
 846         packet_put_char(1);                     /* additional info */
 847         snprintf(prompt, sizeof(prompt),
 848             "Enter %.30s@%.128s's old password: ",
 849             authctxt->server_user, authctxt->host);
 850         password = read_passphrase(prompt, 0);
 851         packet_put_cstring(password);
 852         memset(password, 0, strlen(password));
 853         xfree(password);
 854         password = NULL;
 855         while (password == NULL) {
 856                 snprintf(prompt, sizeof(prompt),
 857                     "Enter %.30s@%.128s's new password: ",
 858                     authctxt->server_user, authctxt->host);
 859                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 860                 if (password == NULL) {
 861                         /* bail out */
 862                         return;
 863                 }
 864                 snprintf(prompt, sizeof(prompt),
 865                     "Retype %.30s@%.128s's new password: ",
 866                     authctxt->server_user, authctxt->host);
 867                 retype = read_passphrase(prompt, 0);
 868                 if (strcmp(password, retype) != 0) {
 869                         memset(password, 0, strlen(password));
 870                         xfree(password);
 871                         logit("Mismatch; try again, EOF to quit.");
 872                         password = NULL;
 873                 }
 874                 memset(retype, 0, strlen(retype));
 875                 xfree(retype);
 876         }
 877         packet_put_cstring(password);
 878         memset(password, 0, strlen(password));
 879         xfree(password);
 880         packet_add_padding(64);
 881         packet_send();
 882
 883         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 884             &input_userauth_passwd_changereq);
 885 }
 886
 887 static int
 888 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
 889     u_char *data, u_int datalen)
 890 {
 891         Key *prv;
 892         int ret;
 893
 894         /* the agent supports this key */
 895         if (id->ac)
 896                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
 897                     data, datalen));
 898         /*
 899          * we have already loaded the private key or
 900          * the private key is stored in external hardware
 901          */
 902         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
 903                 return (key_sign(id->key, sigp, lenp, data, datalen));
 904         /* load the private key from the file */
 905         if ((prv = load_identity_file(id->filename)) == NULL)
 906                 return (-1);
 907         ret = key_sign(prv, sigp, lenp, data, datalen);
 908         key_free(prv);
 909         return (ret);
 910 }
 911
 912 static int
 913 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
 914 {
 915         Buffer b;
 916         u_char *blob, *signature;
 917         u_int bloblen, slen;
 918         u_int skip = 0;
 919         int ret = -1;
 920         int have_sig = 1;
 921
 922         debug3("sign_and_send_pubkey");
 923
 924         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
 925                 /* we cannot handle this key */
 926                 debug3("sign_and_send_pubkey: cannot handle key");
 927                 return 0;
 928         }
 929         /* data to be signed */
 930         buffer_init(&b);
 931         if (datafellows & SSH_OLD_SESSIONID) {
 932                 buffer_append(&b, session_id2, session_id2_len);
 933                 skip = session_id2_len;
 934         } else {
 935                 buffer_put_string(&b, session_id2, session_id2_len);
 936                 skip = buffer_len(&b);
 937         }
 938         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
 939         buffer_put_cstring(&b, authctxt->server_user);
 940         buffer_put_cstring(&b,
 941             datafellows & SSH_BUG_PKSERVICE ?
 942             "ssh-userauth" :
 943             authctxt->service);
 944         if (datafellows & SSH_BUG_PKAUTH) {
 945                 buffer_put_char(&b, have_sig);
 946         } else {
 947                 buffer_put_cstring(&b, authctxt->method->name);
 948                 buffer_put_char(&b, have_sig);
 949                 buffer_put_cstring(&b, key_ssh_name(id->key));
 950         }
 951         buffer_put_string(&b, blob, bloblen);
 952
 953         /* generate signature */
 954         ret = identity_sign(id, &signature, &slen,
 955             buffer_ptr(&b), buffer_len(&b));
 956         if (ret == -1) {
 957                 xfree(blob);
 958                 buffer_free(&b);
 959                 return 0;
 960         }
 961 #ifdef DEBUG_PK
 962         buffer_dump(&b);
 963 #endif
 964         if (datafellows & SSH_BUG_PKSERVICE) {
 965                 buffer_clear(&b);
 966                 buffer_append(&b, session_id2, session_id2_len);
 967                 skip = session_id2_len;
 968                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
 969                 buffer_put_cstring(&b, authctxt->server_user);
 970                 buffer_put_cstring(&b, authctxt->service);
 971                 buffer_put_cstring(&b, authctxt->method->name);
 972                 buffer_put_char(&b, have_sig);
 973                 if (!(datafellows & SSH_BUG_PKAUTH))
 974                         buffer_put_cstring(&b, key_ssh_name(id->key));
 975                 buffer_put_string(&b, blob, bloblen);
 976         }
 977         xfree(blob);
 978
 979         /* append signature */
 980         buffer_put_string(&b, signature, slen);
 981         xfree(signature);
 982
 983         /* skip session id and packet type */
 984         if (buffer_len(&b) < skip + 1)
 985                 fatal("userauth_pubkey: internal error");
 986         buffer_consume(&b, skip + 1);
 987
 988         /* put remaining data from buffer into packet */
 989         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 990         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
 991         buffer_free(&b);
 992         packet_send();
 993
 994         return 1;
 995 }
 996
 997 static int
 998 send_pubkey_test(Authctxt *authctxt, Identity *id)
 999 {
1000         u_char *blob;
1001         u_int bloblen, have_sig = 0;
1002
1003         debug3("send_pubkey_test");
1004
1005         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1006                 /* we cannot handle this key */
1007                 debug3("send_pubkey_test: cannot handle key");
1008                 return 0;
1009         }
1010         /* register callback for USERAUTH_PK_OK message */
1011         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1012
1013         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1014         packet_put_cstring(authctxt->server_user);
1015         packet_put_cstring(authctxt->service);
1016         packet_put_cstring(authctxt->method->name);
1017         packet_put_char(have_sig);
1018         if (!(datafellows & SSH_BUG_PKAUTH))
1019                 packet_put_cstring(key_ssh_name(id->key));
1020         packet_put_string(blob, bloblen);
1021         xfree(blob);
1022         packet_send();
1023         return 1;
1024 }
1025
1026 static Key *
1027 load_identity_file(char *filename)
1028 {
1029         Key *private;
1030         char prompt[300], *passphrase;
1031         int quit, i;
1032         struct stat st;
1033
1034         if (stat(filename, &st) < 0) {
1035                 debug3("no such identity: %s", filename);
1036                 return NULL;
1037         }
1038         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL);
1039         if (private == NULL) {
1040                 if (options.batch_mode)
1041                         return NULL;
1042                 snprintf(prompt, sizeof prompt,
1043                     "Enter passphrase for key '%.100s': ", filename);
1044                 for (i = 0; i < options.number_of_password_prompts; i++) {
1045                         passphrase = read_passphrase(prompt, 0);
1046                         if (strcmp(passphrase, "") != 0) {
1047                                 private = key_load_private_type(KEY_UNSPEC, filename,
1048                                     passphrase, NULL);
1049                                 quit = 0;
1050                         } else {
1051                                 debug2("no passphrase given, try next key");
1052                                 quit = 1;
1053                         }
1054                         memset(passphrase, 0, strlen(passphrase));
1055                         xfree(passphrase);
1056                         if (private != NULL || quit)
1057                                 break;
1058                         debug2("bad passphrase given, try again...");
1059                 }
1060         }
1061         return private;
1062 }
1063
1064 /*
1065  * try keys in the following order:
1066  *      1. agent keys that are found in the config file
1067  *      2. other agent keys
1068  *      3. keys that are only listed in the config file
1069  */
1070 static void
1071 pubkey_prepare(Authctxt *authctxt)
1072 {
1073         Identity *id;
1074         Idlist agent, files, *preferred;
1075         Key *key;
1076         AuthenticationConnection *ac;
1077         char *comment;
1078         int i, found;
1079
1080         TAILQ_INIT(&agent);     /* keys from the agent */
1081         TAILQ_INIT(&files);     /* keys from the config file */
1082         preferred = &authctxt->keys;
1083         TAILQ_INIT(preferred);  /* preferred order of keys */
1084
1085         /* list of keys stored in the filesystem */
1086         for (i = 0; i < options.num_identity_files; i++) {
1087                 key = options.identity_keys[i];
1088                 if (key && key->type == KEY_RSA1)
1089                         continue;
1090                 options.identity_keys[i] = NULL;
1091                 id = xmalloc(sizeof(*id));
1092                 memset(id, 0, sizeof(*id));
1093                 id->key = key;
1094                 id->filename = xstrdup(options.identity_files[i]);
1095                 TAILQ_INSERT_TAIL(&files, id, next);
1096         }
1097         /* list of keys supported by the agent */
1098         if ((ac = ssh_get_authentication_connection())) {
1099                 for (key = ssh_get_first_identity(ac, &comment, 2);
1100                     key != NULL;
1101                     key = ssh_get_next_identity(ac, &comment, 2)) {
1102                         found = 0;
1103                         TAILQ_FOREACH(id, &files, next) {
1104                                 /* agent keys from the config file are preferred */
1105                                 if (key_equal(key, id->key)) {
1106                                         key_free(key);
1107                                         xfree(comment);
1108                                         TAILQ_REMOVE(&files, id, next);
1109                                         TAILQ_INSERT_TAIL(preferred, id, next);
1110                                         id->ac = ac;
1111                                         found = 1;
1112                                         break;
1113                                 }
1114                         }
1115                         if (!found) {
1116                                 id = xmalloc(sizeof(*id));
1117                                 memset(id, 0, sizeof(*id));
1118                                 id->key = key;
1119                                 id->filename = comment;
1120                                 id->ac = ac;
1121                                 TAILQ_INSERT_TAIL(&agent, id, next);
1122                         }
1123                 }
1124                 /* append remaining agent keys */
1125                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1126                         TAILQ_REMOVE(&agent, id, next);
1127                         TAILQ_INSERT_TAIL(preferred, id, next);
1128                 }
1129                 authctxt->agent = ac;
1130         }
1131         /* append remaining keys from the config file */
1132         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1133                 TAILQ_REMOVE(&files, id, next);
1134                 TAILQ_INSERT_TAIL(preferred, id, next);
1135         }
1136         TAILQ_FOREACH(id, preferred, next) {
1137                 debug2("key: %s (%p)", id->filename, id->key);
1138         }
1139 }
1140
1141 static void
1142 pubkey_cleanup(Authctxt *authctxt)
1143 {
1144         Identity *id;
1145
1146         if (authctxt->agent != NULL)
1147                 ssh_close_authentication_connection(authctxt->agent);
1148         for (id = TAILQ_FIRST(&authctxt->keys); id;
1149             id = TAILQ_FIRST(&authctxt->keys)) {
1150                 TAILQ_REMOVE(&authctxt->keys, id, next);
1151                 if (id->key)
1152                         key_free(id->key);
1153                 if (id->filename)
1154                         xfree(id->filename);
1155                 xfree(id);
1156         }
1157 }
1158
1159 int
1160 userauth_pubkey(Authctxt *authctxt)
1161 {
1162         Identity *id;
1163         int sent = 0;
1164
1165         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1166                 if (id->tried++)
1167                         return (0);
1168                 TAILQ_REMOVE(&authctxt->keys, id, next);
1169                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1170                 /*
1171                  * send a test message if we have the public key. for
1172                  * encrypted keys we cannot do this and have to load the
1173                  * private key instead
1174                  */
1175                 if (id->key && id->key->type != KEY_RSA1) {
1176                         debug("Offering public key: %s", id->filename);
1177                         sent = send_pubkey_test(authctxt, id);
1178                 } else if (id->key == NULL) {
1179                         debug("Trying private key: %s", id->filename);
1180                         id->key = load_identity_file(id->filename);
1181                         if (id->key != NULL) {
1182                                 id->isprivate = 1;
1183                                 sent = sign_and_send_pubkey(authctxt, id);
1184                                 key_free(id->key);
1185                                 id->key = NULL;
1186                         }
1187                 }
1188                 if (sent)
1189                         return (sent);
1190         }
1191         return (0);
1192 }
1193
1194 /*
1195  * Send userauth request message specifying keyboard-interactive method.
1196  */
1197 int
1198 userauth_kbdint(Authctxt *authctxt)
1199 {
1200         static int attempt = 0;
1201
1202         if (attempt++ >= options.number_of_password_prompts)
1203                 return 0;
1204         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1205         if (attempt > 1 && !authctxt->info_req_seen) {
1206                 debug3("userauth_kbdint: disable: no info_req_seen");
1207                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1208                 return 0;
1209         }
1210
1211         debug2("userauth_kbdint");
1212         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1213         packet_put_cstring(authctxt->server_user);
1214         packet_put_cstring(authctxt->service);
1215         packet_put_cstring(authctxt->method->name);
1216         packet_put_cstring("");                                 /* lang */
1217         packet_put_cstring(options.kbd_interactive_devices ?
1218             options.kbd_interactive_devices : "");
1219         packet_send();
1220
1221         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1222         return 1;
1223 }
1224
1225 /*
1226  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1227  */
1228 void
1229 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1230 {
1231         Authctxt *authctxt = ctxt;
1232         char *name, *inst, *lang, *prompt, *response;
1233         u_int num_prompts, i;
1234         int echo = 0;
1235
1236         debug2("input_userauth_info_req");
1237
1238         if (authctxt == NULL)
1239                 fatal("input_userauth_info_req: no authentication context");
1240
1241         authctxt->info_req_seen = 1;
1242
1243         name = packet_get_string(NULL);
1244         inst = packet_get_string(NULL);
1245         lang = packet_get_string(NULL);
1246         if (strlen(name) > 0)
1247                 logit("%s", name);
1248         if (strlen(inst) > 0)
1249                 logit("%s", inst);
1250         xfree(name);
1251         xfree(inst);
1252         xfree(lang);
1253
1254         num_prompts = packet_get_int();
1255         /*
1256          * Begin to build info response packet based on prompts requested.
1257          * We commit to providing the correct number of responses, so if
1258          * further on we run into a problem that prevents this, we have to
1259          * be sure and clean this up and send a correct error response.
1260          */
1261         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1262         packet_put_int(num_prompts);
1263
1264         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1265         for (i = 0; i < num_prompts; i++) {
1266                 prompt = packet_get_string(NULL);
1267                 echo = packet_get_char();
1268
1269                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1270
1271                 packet_put_cstring(response);
1272                 memset(response, 0, strlen(response));
1273                 xfree(response);
1274                 xfree(prompt);
1275         }
1276         packet_check_eom(); /* done with parsing incoming message. */
1277
1278         packet_add_padding(64);
1279         packet_send();
1280 }
1281
1282 static int
1283 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1284     u_char *data, u_int datalen)
1285 {
1286         Buffer b;
1287         struct stat st;
1288         pid_t pid;
1289         int to[2], from[2], status, version = 2;
1290
1291         debug2("ssh_keysign called");
1292
1293         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1294                 error("ssh_keysign: no installed: %s", strerror(errno));
1295                 return -1;
1296         }
1297         if (fflush(stdout) != 0)
1298                 error("ssh_keysign: fflush: %s", strerror(errno));
1299         if (pipe(to) < 0) {
1300                 error("ssh_keysign: pipe: %s", strerror(errno));
1301                 return -1;
1302         }
1303         if (pipe(from) < 0) {
1304                 error("ssh_keysign: pipe: %s", strerror(errno));
1305                 return -1;
1306         }
1307         if ((pid = fork()) < 0) {
1308                 error("ssh_keysign: fork: %s", strerror(errno));
1309                 return -1;
1310         }
1311         if (pid == 0) {
1312                 seteuid(getuid());
1313                 setuid(getuid());
1314                 close(from[0]);
1315                 if (dup2(from[1], STDOUT_FILENO) < 0)
1316                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1317                 close(to[1]);
1318                 if (dup2(to[0], STDIN_FILENO) < 0)
1319                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1320                 close(from[1]);
1321                 close(to[0]);
1322                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1323                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1324                     strerror(errno));
1325         }
1326         close(from[1]);
1327         close(to[0]);
1328
1329         buffer_init(&b);
1330         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1331         buffer_put_string(&b, data, datalen);
1332         ssh_msg_send(to[1], version, &b);
1333
1334         if (ssh_msg_recv(from[0], &b) < 0) {
1335                 error("ssh_keysign: no reply");
1336                 buffer_clear(&b);
1337                 return -1;
1338         }
1339         close(from[0]);
1340         close(to[1]);
1341
1342         while (waitpid(pid, &status, 0) < 0)
1343                 if (errno != EINTR)
1344                         break;
1345
1346         if (buffer_get_char(&b) != version) {
1347                 error("ssh_keysign: bad version");
1348                 buffer_clear(&b);
1349                 return -1;
1350         }
1351         *sigp = buffer_get_string(&b, lenp);
1352         buffer_clear(&b);
1353
1354         return 0;
1355 }
1356
1357 int
1358 userauth_hostbased(Authctxt *authctxt)
1359 {
1360         Key *private = NULL;
1361         Sensitive *sensitive = authctxt->sensitive;
1362         Buffer b;
1363         u_char *signature, *blob;
1364         char *chost, *pkalg, *p;
1365         const char *service;
1366         u_int blen, slen;
1367         int ok, i, len, found = 0;
1368
1369         /* check for a useful key */
1370         for (i = 0; i < sensitive->nkeys; i++) {
1371                 private = sensitive->keys[i];
1372                 if (private && private->type != KEY_RSA1) {
1373                         found = 1;
1374                         /* we take and free the key */
1375                         sensitive->keys[i] = NULL;
1376                         break;
1377                 }
1378         }
1379         if (!found) {
1380                 debug("No more client hostkeys for hostbased authentication.");
1381                 return 0;
1382         }
1383         if (key_to_blob(private, &blob, &blen) == 0) {
1384                 key_free(private);
1385                 return 0;
1386         }
1387         /* figure out a name for the client host */
1388         p = get_local_name(packet_get_connection_in());
1389         if (p == NULL) {
1390                 error("userauth_hostbased: cannot get local ipaddr/name");
1391                 key_free(private);
1392                 return 0;
1393         }
1394         len = strlen(p) + 2;
1395         chost = xmalloc(len);
1396         strlcpy(chost, p, len);
1397         strlcat(chost, ".", len);
1398         debug2("userauth_hostbased: chost %s", chost);
1399         xfree(p);
1400
1401         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1402             authctxt->service;
1403         pkalg = xstrdup(key_ssh_name(private));
1404         buffer_init(&b);
1405         /* construct data */
1406         buffer_put_string(&b, session_id2, session_id2_len);
1407         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1408         buffer_put_cstring(&b, authctxt->server_user);
1409         buffer_put_cstring(&b, service);
1410         buffer_put_cstring(&b, authctxt->method->name);
1411         buffer_put_cstring(&b, pkalg);
1412         buffer_put_string(&b, blob, blen);
1413         buffer_put_cstring(&b, chost);
1414         buffer_put_cstring(&b, authctxt->local_user);
1415 #ifdef DEBUG_PK
1416         buffer_dump(&b);
1417 #endif
1418         if (sensitive->external_keysign)
1419                 ok = ssh_keysign(private, &signature, &slen,
1420                     buffer_ptr(&b), buffer_len(&b));
1421         else
1422                 ok = key_sign(private, &signature, &slen,
1423                     buffer_ptr(&b), buffer_len(&b));
1424         key_free(private);
1425         buffer_free(&b);
1426         if (ok != 0) {
1427                 error("key_sign failed");
1428                 xfree(chost);
1429                 xfree(pkalg);
1430                 return 0;
1431         }
1432         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1433         packet_put_cstring(authctxt->server_user);
1434         packet_put_cstring(authctxt->service);
1435         packet_put_cstring(authctxt->method->name);
1436         packet_put_cstring(pkalg);
1437         packet_put_string(blob, blen);
1438         packet_put_cstring(chost);
1439         packet_put_cstring(authctxt->local_user);
1440         packet_put_string(signature, slen);
1441         memset(signature, 's', slen);
1442         xfree(signature);
1443         xfree(chost);
1444         xfree(pkalg);
1445
1446         packet_send();
1447         return 1;
1448 }
1449
1450 /* find auth method */
1451
1452 /*
1453  * given auth method name, if configurable options permit this method fill
1454  * in auth_ident field and return true, otherwise return false.
1455  */
1456 static int
1457 authmethod_is_enabled(Authmethod *method)
1458 {
1459         if (method == NULL)
1460                 return 0;
1461         /* return false if options indicate this method is disabled */
1462         if  (method->enabled == NULL || *method->enabled == 0)
1463                 return 0;
1464         /* return false if batch mode is enabled but method needs interactive mode */
1465         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1466                 return 0;
1467         return 1;
1468 }
1469
1470 static Authmethod *
1471 authmethod_lookup(const char *name)
1472 {
1473         Authmethod *method = NULL;
1474         if (name != NULL)
1475                 for (method = authmethods; method->name != NULL; method++)
1476                         if (strcmp(name, method->name) == 0)
1477                                 return method;
1478         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1479         return NULL;
1480 }
1481
1482 /* XXX internal state */
1483 static Authmethod *current = NULL;
1484 static char *supported = NULL;
1485 static char *preferred = NULL;
1486
1487 /*
1488  * Given the authentication method list sent by the server, return the
1489  * next method we should try.  If the server initially sends a nil list,
1490  * use a built-in default list.
1491  */
1492 static Authmethod *
1493 authmethod_get(char *authlist)
1494 {
1495         char *name = NULL;
1496         u_int next;
1497
1498         /* Use a suitable default if we're passed a nil list.  */
1499         if (authlist == NULL || strlen(authlist) == 0)
1500                 authlist = options.preferred_authentications;
1501
1502         if (supported == NULL || strcmp(authlist, supported) != 0) {
1503                 debug3("start over, passed a different list %s", authlist);
1504                 if (supported != NULL)
1505                         xfree(supported);
1506                 supported = xstrdup(authlist);
1507                 preferred = options.preferred_authentications;
1508                 debug3("preferred %s", preferred);
1509                 current = NULL;
1510         } else if (current != NULL && authmethod_is_enabled(current))
1511                 return current;
1512
1513         for (;;) {
1514                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1515                         debug("No more authentication methods to try.");
1516                         current = NULL;
1517                         return NULL;
1518                 }
1519                 preferred += next;
1520                 debug3("authmethod_lookup %s", name);
1521                 debug3("remaining preferred: %s", preferred);
1522                 if ((current = authmethod_lookup(name)) != NULL &&
1523                     authmethod_is_enabled(current)) {
1524                         debug3("authmethod_is_enabled %s", name);
1525                         debug("Next authentication method: %s", name);
1526                         return current;
1527                 }
1528         }
1529 }
1530
1531 static char *
1532 authmethods_get(void)
1533 {
1534         Authmethod *method = NULL;
1535         Buffer b;
1536         char *list;
1537
1538         buffer_init(&b);
1539         for (method = authmethods; method->name != NULL; method++) {
1540                 if (authmethod_is_enabled(method)) {
1541                         if (buffer_len(&b) > 0)
1542                                 buffer_append(&b, ",", 1);
1543                         buffer_append(&b, method->name, strlen(method->name));
1544                 }
1545         }
1546         buffer_append(&b, "\0", 1);
1547         list = xstrdup(buffer_ptr(&b));
1548         buffer_free(&b);
1549         return list;
1550 }