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 1.135 2004/03/05 10:53:58 markus 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         /* 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,none";
 123         } else {
 124                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 125                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,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_GEX_SHA1] = kexgex_client;
 153 #ifdef GSSAPI
 154         kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client;
 155 #endif
 156         kex->client_version_string=client_version_string;
 157         kex->server_version_string=server_version_string;
 158         kex->verify_host_key=&verify_host_key_callback;
 159 #ifdef GSSAPI
 160         kex->options.gss_deleg_creds=options.gss_deleg_creds;
 161 #endif
 162
 163         xxx_kex = kex;
 164
 165         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 166
 167         session_id2 = kex->session_id;
 168         session_id2_len = kex->session_id_len;
 169
 170 #ifdef DEBUG_KEXDH
 171         /* send 1st encrypted/maced/compressed message */
 172         packet_start(SSH2_MSG_IGNORE);
 173         packet_put_cstring("markus");
 174         packet_send();
 175         packet_write_wait();
 176 #endif
 177 }
 178
 179 /*
 180  * Authenticate user
 181  */
 182
 183 typedef struct Authctxt Authctxt;
 184 typedef struct Authmethod Authmethod;
 185 typedef struct identity Identity;
 186 typedef struct idlist Idlist;
 187
 188 struct identity {
 189         TAILQ_ENTRY(identity) next;
 190         AuthenticationConnection *ac;   /* set if agent supports key */
 191         Key     *key;                   /* public/private key */
 192         char    *filename;              /* comment for agent-only keys */
 193         int     tried;
 194         int     isprivate;              /* key points to the private key */
 195 };
 196 TAILQ_HEAD(idlist, identity);
 197
 198 struct Authctxt {
 199         const char *server_user;
 200         const char *local_user;
 201         const char *host;
 202         const char *service;
 203         Authmethod *method;
 204         int success;
 205         char *authlist;
 206         /* pubkey */
 207         Idlist keys;
 208         AuthenticationConnection *agent;
 209         /* hostbased */
 210         Sensitive *sensitive;
 211         /* kbd-interactive */
 212         int info_req_seen;
 213         /* generic */
 214         void *methoddata;
 215 };
 216 struct Authmethod {
 217         char    *name;          /* string to compare against server's list */
 218         int     (*userauth)(Authctxt *authctxt);
 219         int     *enabled;       /* flag in option struct that enables method */
 220         int     *batch_flag;    /* flag in option struct that disables method */
 221 };
 222
 223 void    input_userauth_success(int, u_int32_t, void *);
 224 void    input_userauth_failure(int, u_int32_t, void *);
 225 void    input_userauth_banner(int, u_int32_t, void *);
 226 void    input_userauth_error(int, u_int32_t, void *);
 227 void    input_userauth_info_req(int, u_int32_t, void *);
 228 void    input_userauth_pk_ok(int, u_int32_t, void *);
 229 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 230
 231 int     userauth_none(Authctxt *);
 232 int     userauth_pubkey(Authctxt *);
 233 int     userauth_passwd(Authctxt *);
 234 int     userauth_kbdint(Authctxt *);
 235 int     userauth_hostbased(Authctxt *);
 236 int     userauth_kerberos(Authctxt *);
 237
 238 #ifdef GSSAPI
 239 int     userauth_gssapi(Authctxt *authctxt);
 240 void    input_gssapi_response(int type, u_int32_t, void *);
 241 void    input_gssapi_token(int type, u_int32_t, void *);
 242 void    input_gssapi_hash(int type, u_int32_t, void *);
 243 void    input_gssapi_error(int, u_int32_t, void *);
 244 void    input_gssapi_errtok(int, u_int32_t, void *);
 245 #endif
 246
 247 #ifdef GSSAPI
 248 int     userauth_external(Authctxt *authctxt);
 249 int     userauth_gssapi(Authctxt *authctxt);
 250 int     userauth_gssapi_with_mic(Authctxt *authctxt);
 251 int     userauth_gssapi_without_mic(Authctxt *authctxt);
 252 void    input_gssapi_response(int type, u_int32_t, void *);
 253 void    input_gssapi_token(int type, u_int32_t, void *);
 254 void    input_gssapi_hash(int type, u_int32_t, void *);
 255 void    input_gssapi_error(int, u_int32_t, void *);
 256 void    input_gssapi_errtok(int, u_int32_t, void *);
 257 #endif
 258
 259 void    userauth(Authctxt *, char *);
 260
 261 static int sign_and_send_pubkey(Authctxt *, Identity *);
 262 static void pubkey_prepare(Authctxt *);
 263 static void pubkey_cleanup(Authctxt *);
 264 static Key *load_identity_file(char *);
 265
 266 static Authmethod *authmethod_get(char *authlist);
 267 static Authmethod *authmethod_lookup(const char *name);
 268 static char *authmethods_get(void);
 269
 270 Authmethod authmethods[] = {
 271 #ifdef GSSAPI
 272         {"external-keyx",
 273                 userauth_external,
 274                 &options.gss_authentication,
 275                 NULL},
 276         {"gssapi-with-mic",
 277                 userauth_gssapi,
 278                 &options.gss_authentication,
 279                 NULL},
 280         {"gssapi",
 281                 userauth_gssapi,
 282                 &options.gss_authentication,
 283                 NULL},
 284 #endif
 285         {"hostbased",
 286                 userauth_hostbased,
 287                 &options.hostbased_authentication,
 288                 NULL},
 289         {"publickey",
 290                 userauth_pubkey,
 291                 &options.pubkey_authentication,
 292                 NULL},
 293         {"keyboard-interactive",
 294                 userauth_kbdint,
 295                 &options.kbd_interactive_authentication,
 296                 &options.batch_mode},
 297         {"password",
 298                 userauth_passwd,
 299                 &options.password_authentication,
 300                 &options.batch_mode},
 301         {"none",
 302                 userauth_none,
 303                 NULL,
 304                 NULL},
 305         {NULL, NULL, NULL, NULL}
 306 };
 307
 308 void
 309 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 310     Sensitive *sensitive)
 311 {
 312         Authctxt authctxt;
 313         int type;
 314
 315         if (options.challenge_response_authentication)
 316                 options.kbd_interactive_authentication = 1;
 317
 318         packet_start(SSH2_MSG_SERVICE_REQUEST);
 319         packet_put_cstring("ssh-userauth");
 320         packet_send();
 321         debug("SSH2_MSG_SERVICE_REQUEST sent");
 322         packet_write_wait();
 323         type = packet_read();
 324         if (type != SSH2_MSG_SERVICE_ACCEPT)
 325                 fatal("Server denied authentication request: %d", type);
 326         if (packet_remaining() > 0) {
 327                 char *reply = packet_get_string(NULL);
 328                 debug2("service_accept: %s", reply);
 329                 xfree(reply);
 330         } else {
 331                 debug2("buggy server: service_accept w/o service");
 332         }
 333         packet_check_eom();
 334         debug("SSH2_MSG_SERVICE_ACCEPT received");
 335
 336         if (options.preferred_authentications == NULL)
 337                 options.preferred_authentications = authmethods_get();
 338
 339         /* setup authentication context */
 340         memset(&authctxt, 0, sizeof(authctxt));
 341         pubkey_prepare(&authctxt);
 342         authctxt.server_user = server_user;
 343         authctxt.local_user = local_user;
 344         authctxt.host = host;
 345         authctxt.service = "ssh-connection";            /* service name */
 346         authctxt.success = 0;
 347         authctxt.method = authmethod_lookup("none");
 348         authctxt.authlist = NULL;
 349         authctxt.methoddata = NULL;
 350         authctxt.sensitive = sensitive;
 351         authctxt.info_req_seen = 0;
 352         if (authctxt.method == NULL)
 353                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 354
 355         /* initial userauth request */
 356         userauth_none(&authctxt);
 357
 358         dispatch_init(&input_userauth_error);
 359         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 360         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 361         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 362         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 363
 364         pubkey_cleanup(&authctxt);
 365         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 366
 367         debug("Authentication succeeded (%s).", authctxt.method->name);
 368 }
 369
 370 void
 371 userauth(Authctxt *authctxt, char *authlist)
 372 {
 373         if (authctxt->methoddata) {
 374                 xfree(authctxt->methoddata);
 375                 authctxt->methoddata = NULL;
 376         }
 377         if (authlist == NULL) {
 378                 authlist = authctxt->authlist;
 379         } else {
 380                 if (authctxt->authlist)
 381                         xfree(authctxt->authlist);
 382                 authctxt->authlist = authlist;
 383         }
 384         for (;;) {
 385                 Authmethod *method = authmethod_get(authlist);
 386                 if (method == NULL)
 387                         fatal("Permission denied (%s).", authlist);
 388                 authctxt->method = method;
 389
 390                 /* reset the per method handler */
 391                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 392                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 393
 394                 /* and try new method */
 395                 if (method->userauth(authctxt) != 0) {
 396                         debug2("we sent a %s packet, wait for reply", method->name);
 397                         break;
 398                 } else {
 399                         debug2("we did not send a packet, disable method");
 400                         method->enabled = NULL;
 401                 }
 402         }
 403 }
 404
 405 void
 406 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 407 {
 408         fatal("input_userauth_error: bad message during authentication: "
 409            "type %d", type);
 410 }
 411
 412 void
 413 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 414 {
 415         char *msg, *lang;
 416
 417         debug3("input_userauth_banner");
 418         msg = packet_get_string(NULL);
 419         lang = packet_get_string(NULL);
 420         if (options.log_level > SYSLOG_LEVEL_QUIET)
 421                 fprintf(stderr, "%s", msg);
 422         xfree(msg);
 423         xfree(lang);
 424 }
 425
 426 void
 427 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 428 {
 429         Authctxt *authctxt = ctxt;
 430         if (authctxt == NULL)
 431                 fatal("input_userauth_success: no authentication context");
 432         if (authctxt->authlist) {
 433                 xfree(authctxt->authlist);
 434                 authctxt->authlist = NULL;
 435         }
 436         if (authctxt->methoddata) {
 437                 xfree(authctxt->methoddata);
 438                 authctxt->methoddata = NULL;
 439         }
 440         authctxt->success = 1;                  /* break out */
 441 }
 442
 443 void
 444 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 445 {
 446         Authctxt *authctxt = ctxt;
 447         char *authlist = NULL;
 448         int partial;
 449
 450         if (authctxt == NULL)
 451                 fatal("input_userauth_failure: no authentication context");
 452
 453         authlist = packet_get_string(NULL);
 454         partial = packet_get_char();
 455         packet_check_eom();
 456
 457         if (partial != 0)
 458                 logit("Authenticated with partial success.");
 459         debug("Authentications that can continue: %s", authlist);
 460
 461         userauth(authctxt, authlist);
 462 }
 463 void
 464 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 465 {
 466         Authctxt *authctxt = ctxt;
 467         Key *key = NULL;
 468         Identity *id = NULL;
 469         Buffer b;
 470         int pktype, sent = 0;
 471         u_int alen, blen;
 472         char *pkalg, *fp;
 473         u_char *pkblob;
 474
 475         if (authctxt == NULL)
 476                 fatal("input_userauth_pk_ok: no authentication context");
 477         if (datafellows & SSH_BUG_PKOK) {
 478                 /* this is similar to SSH_BUG_PKAUTH */
 479                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 480                 pkblob = packet_get_string(&blen);
 481                 buffer_init(&b);
 482                 buffer_append(&b, pkblob, blen);
 483                 pkalg = buffer_get_string(&b, &alen);
 484                 buffer_free(&b);
 485         } else {
 486                 pkalg = packet_get_string(&alen);
 487                 pkblob = packet_get_string(&blen);
 488         }
 489         packet_check_eom();
 490
 491         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 492
 493         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 494                 debug("unknown pkalg %s", pkalg);
 495                 goto done;
 496         }
 497         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 498                 debug("no key from blob. pkalg %s", pkalg);
 499                 goto done;
 500         }
 501         if (key->type != pktype) {
 502                 error("input_userauth_pk_ok: type mismatch "
 503                     "for decoded key (received %d, expected %d)",
 504                     key->type, pktype);
 505                 goto done;
 506         }
 507         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 508         debug2("input_userauth_pk_ok: fp %s", fp);
 509         xfree(fp);
 510
 511         /*
 512          * search keys in the reverse order, because last candidate has been
 513          * moved to the end of the queue.  this also avoids confusion by
 514          * duplicate keys
 515          */
 516         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, next, idlist) {
 517                 if (key_equal(key, id->key)) {
 518                         sent = sign_and_send_pubkey(authctxt, id);
 519                         break;
 520                 }
 521         }
 522 done:
 523         if (key != NULL)
 524                 key_free(key);
 525         xfree(pkalg);
 526         xfree(pkblob);
 527
 528         /* try another method if we did not send a packet */
 529         if (sent == 0)
 530                 userauth(authctxt, NULL);
 531 }
 532
 533 #ifdef GSSAPI
 534 int
 535 userauth_gssapi(Authctxt *authctxt)
 536 {
 537         Gssctxt *gssctxt = NULL;
 538         static gss_OID_set gss_supported = NULL;
 539         static int mech = 0;
 540         OM_uint32 min;
 541         int ok = 0;
 542
 543         if (!options.gss_authentication) {
 544                 verbose("GSSAPI authentication disabled.");
 545                 return 0;
 546         }
 547
 548         /* Try one GSSAPI method at a time, rather than sending them all at
 549          * once. */
 550
 551         if (gss_supported == NULL)
 552                 gss_indicate_mechs(&min, &gss_supported);
 553
 554         /* Check to see if the mechanism is usable before we offer it */
 555         while (mech < gss_supported->count && !ok) {
 556                 if (gssctxt)
 557                         ssh_gssapi_delete_ctx(&gssctxt);
 558                 ssh_gssapi_build_ctx(&gssctxt);
 559                 ssh_gssapi_set_oid(gssctxt, &gss_supported->elements[mech]);
 560
 561                 /* My DER encoding requires length<128 */
 562                 if (gss_supported->elements[mech].length < 128 &&
 563                     !GSS_ERROR(ssh_gssapi_import_name(gssctxt,
 564                                                 get_canonical_hostname(1)))) {
 565                         ok = 1; /* Mechanism works */
 566                 } else {
 567                         mech++;
 568                 }
 569         }
 570
 571         if (!ok) return 0;
 572
 573         authctxt->methoddata=(void *)gssctxt;
 574
 575         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 576         packet_put_cstring(authctxt->server_user);
 577         packet_put_cstring(authctxt->service);
 578         packet_put_cstring(authctxt->method->name);
 579
 580         packet_put_int(1);
 581
 582         /* Some servers encode the OID incorrectly (as we used to) */
 583         if (datafellows & SSH_BUG_GSSAPI_BER) {
 584                 packet_put_string(gss_supported->elements[mech].elements,
 585                     gss_supported->elements[mech].length);
 586         } else {
 587                 packet_put_int((gss_supported->elements[mech].length)+2);
 588                 packet_put_char(SSH_GSS_OIDTYPE);
 589                 packet_put_char(gss_supported->elements[mech].length);
 590                 packet_put_raw(gss_supported->elements[mech].elements,
 591                     gss_supported->elements[mech].length);
 592         }
 593
 594         packet_send();
 595
 596         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 597         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 598         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 599         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 600
 601         mech++; /* Move along to next candidate */
 602
 603         return 1;
 604 }
 605
 606 static OM_uint32
 607 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 608 {
 609         Authctxt *authctxt = ctxt;
 610         Gssctxt *gssctxt = authctxt->methoddata;
 611         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 612         gss_buffer_desc gssbuf, mic;
 613         OM_uint32 status, ms, flags;
 614         Buffer b;
 615
 616         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 617             recv_tok, &send_tok, &flags);
 618
 619         if (send_tok.length > 0) {
 620                 if (GSS_ERROR(status))
 621                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 622                 else
 623                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 624
 625                 packet_put_string(send_tok.value, send_tok.length);
 626                 packet_send();
 627                 gss_release_buffer(&ms, &send_tok);
 628         }
 629
 630         if (status == GSS_S_COMPLETE) {
 631                 /* send either complete or MIC, depending on mechanism */
 632                 if (strcmp(authctxt->method->name,"gssapi")==0 ||
 633                     (!(flags & GSS_C_INTEG_FLAG))) {
 634                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 635                         packet_send();
 636                 } else {
 637                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 638                             authctxt->service, "gssapi-with-mic");
 639
 640                         gssbuf.value = buffer_ptr(&b);
 641                         gssbuf.length = buffer_len(&b);
 642
 643                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 644
 645                         if (!GSS_ERROR(status)) {
 646                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 647                                 packet_put_string(mic.value, mic.length);
 648
 649                                 packet_send();
 650                         }
 651
 652                         buffer_free(&b);
 653                         gss_release_buffer(&ms, &mic);
 654                 }
 655         }
 656
 657         return status;
 658 }
 659
 660 void
 661 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 662 {
 663         Authctxt *authctxt = ctxt;
 664         Gssctxt *gssctxt;
 665         int oidlen;
 666         char *oidv;
 667
 668         if (authctxt == NULL)
 669                 fatal("input_gssapi_response: no authentication context");
 670         gssctxt = authctxt->methoddata;
 671
 672         /* Setup our OID */
 673         oidv = packet_get_string(&oidlen);
 674
 675         if (datafellows & SSH_BUG_GSSAPI_BER) {
 676                 if (!ssh_gssapi_check_oid(gssctxt, oidv, oidlen))
 677                         fatal("Server returned different OID than expected");
 678         } else {
 679                 if(oidv[0] != SSH_GSS_OIDTYPE || oidv[1] != oidlen-2) {
 680                         debug("Badly encoded mechanism OID received");
 681                         userauth(authctxt, NULL);
 682                         xfree(oidv);
 683                         return;
 684                 }
 685                 if (!ssh_gssapi_check_oid(gssctxt, oidv+2, oidlen-2))
 686                         fatal("Server returned different OID than expected");
 687         }
 688
 689         packet_check_eom();
 690
 691         xfree(oidv);
 692
 693         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 694                 /* Start again with next method on list */
 695                 debug("Trying to start again");
 696                 userauth(authctxt, NULL);
 697                 return;
 698         }
 699 }
 700
 701 void
 702 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 703 {
 704         Authctxt *authctxt = ctxt;
 705         gss_buffer_desc recv_tok;
 706         OM_uint32 status;
 707         u_int slen;
 708
 709         if (authctxt == NULL)
 710                 fatal("input_gssapi_response: no authentication context");
 711
 712         recv_tok.value = packet_get_string(&slen);
 713         recv_tok.length = slen; /* safe typecast */
 714
 715         packet_check_eom();
 716
 717         status = process_gssapi_token(ctxt, &recv_tok);
 718
 719         xfree(recv_tok.value);
 720
 721         if (GSS_ERROR(status)) {
 722                 /* Start again with the next method in the list */
 723                 userauth(authctxt, NULL);
 724                 return;
 725         }
 726 }
 727
 728 void
 729 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 730 {
 731         Authctxt *authctxt = ctxt;
 732         Gssctxt *gssctxt;
 733         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 734         gss_buffer_desc recv_tok;
 735         OM_uint32 status, ms;
 736         u_int len;
 737
 738         if (authctxt == NULL)
 739                 fatal("input_gssapi_response: no authentication context");
 740         gssctxt = authctxt->methoddata;
 741
 742         recv_tok.value = packet_get_string(&len);
 743         recv_tok.length = len;
 744
 745         packet_check_eom();
 746
 747         /* Stick it into GSSAPI and see what it says */
 748         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 749                                      &recv_tok, &send_tok, NULL);
 750
 751         xfree(recv_tok.value);
 752         gss_release_buffer(&ms, &send_tok);
 753
 754         /* Server will be returning a failed packet after this one */
 755 }
 756
 757 void
 758 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 759 {
 760         OM_uint32 maj, min;
 761         char *msg;
 762         char *lang;
 763
 764         maj=packet_get_int();
 765         min=packet_get_int();
 766         msg=packet_get_string(NULL);
 767         lang=packet_get_string(NULL);
 768
 769         packet_check_eom();
 770
 771         debug("Server GSSAPI Error:\n%s\n", msg);
 772         xfree(msg);
 773         xfree(lang);
 774 }
 775
 776 int
 777 userauth_external(Authctxt *authctxt)
 778 {
 779         static int attempt = 0;
 780
 781         if (attempt++ >= 1)
 782                 return 0;
 783
 784         /* The client MUST NOT try this method if initial key exchange
 785            was not performed using a GSSAPI-based key exchange
 786            method. */
 787         if (xxx_kex->kex_type != KEX_GSS_GRP1_SHA1) {
 788                 debug2("gsskex not performed, skipping external-keyx");
 789                 return 0;
 790         }
 791
 792         debug2("userauth_external");
 793         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 794 #ifdef GSI
 795         if(options.implicit && !(datafellows & SSH_BUG_GSS_EMPTYUSER)) {
 796             packet_put_cstring("");
 797         } else {
 798 #endif
 799             packet_put_cstring(authctxt->server_user);
 800 #ifdef GSI
 801         }
 802 #endif
 803         packet_put_cstring(authctxt->service);
 804         packet_put_cstring(authctxt->method->name);
 805         packet_send();
 806         packet_write_wait();
 807         return 1;
 808 }
 809 #endif /* GSSAPI */
 810
 811 int
 812 userauth_none(Authctxt *authctxt)
 813 {
 814         /* initial userauth request */
 815         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 816         packet_put_cstring(authctxt->server_user);
 817         packet_put_cstring(authctxt->service);
 818         packet_put_cstring(authctxt->method->name);
 819         packet_send();
 820         return 1;
 821 }
 822
 823 int
 824 userauth_passwd(Authctxt *authctxt)
 825 {
 826         static int attempt = 0;
 827         char prompt[150];
 828         char *password;
 829
 830         if (attempt++ >= options.number_of_password_prompts)
 831                 return 0;
 832
 833         if (attempt != 1)
 834                 error("Permission denied, please try again.");
 835
 836         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 837             authctxt->server_user, authctxt->host);
 838         password = read_passphrase(prompt, 0);
 839         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 840         packet_put_cstring(authctxt->server_user);
 841         packet_put_cstring(authctxt->service);
 842         packet_put_cstring(authctxt->method->name);
 843         packet_put_char(0);
 844         packet_put_cstring(password);
 845         memset(password, 0, strlen(password));
 846         xfree(password);
 847         packet_add_padding(64);
 848         packet_send();
 849
 850         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 851             &input_userauth_passwd_changereq);
 852
 853         return 1;
 854 }
 855 /*
 856  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 857  */
 858 void
 859 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 860 {
 861         Authctxt *authctxt = ctxt;
 862         char *info, *lang, *password = NULL, *retype = NULL;
 863         char prompt[150];
 864
 865         debug2("input_userauth_passwd_changereq");
 866
 867         if (authctxt == NULL)
 868                 fatal("input_userauth_passwd_changereq: "
 869                     "no authentication context");
 870
 871         info = packet_get_string(NULL);
 872         lang = packet_get_string(NULL);
 873         if (strlen(info) > 0)
 874                 logit("%s", info);
 875         xfree(info);
 876         xfree(lang);
 877         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 878         packet_put_cstring(authctxt->server_user);
 879         packet_put_cstring(authctxt->service);
 880         packet_put_cstring(authctxt->method->name);
 881         packet_put_char(1);                     /* additional info */
 882         snprintf(prompt, sizeof(prompt),
 883             "Enter %.30s@%.128s's old password: ",
 884             authctxt->server_user, authctxt->host);
 885         password = read_passphrase(prompt, 0);
 886         packet_put_cstring(password);
 887         memset(password, 0, strlen(password));
 888         xfree(password);
 889         password = NULL;
 890         while (password == NULL) {
 891                 snprintf(prompt, sizeof(prompt),
 892                     "Enter %.30s@%.128s's new password: ",
 893                     authctxt->server_user, authctxt->host);
 894                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 895                 if (password == NULL) {
 896                         /* bail out */
 897                         return;
 898                 }
 899                 snprintf(prompt, sizeof(prompt),
 900                     "Retype %.30s@%.128s's new password: ",
 901                     authctxt->server_user, authctxt->host);
 902                 retype = read_passphrase(prompt, 0);
 903                 if (strcmp(password, retype) != 0) {
 904                         memset(password, 0, strlen(password));
 905                         xfree(password);
 906                         logit("Mismatch; try again, EOF to quit.");
 907                         password = NULL;
 908                 }
 909                 memset(retype, 0, strlen(retype));
 910                 xfree(retype);
 911         }
 912         packet_put_cstring(password);
 913         memset(password, 0, strlen(password));
 914         xfree(password);
 915         packet_add_padding(64);
 916         packet_send();
 917
 918         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 919             &input_userauth_passwd_changereq);
 920 }
 921
 922 static int
 923 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
 924     u_char *data, u_int datalen)
 925 {
 926         Key *prv;
 927         int ret;
 928
 929         /* the agent supports this key */
 930         if (id->ac)
 931                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
 932                     data, datalen));
 933         /*
 934          * we have already loaded the private key or
 935          * the private key is stored in external hardware
 936          */
 937         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
 938                 return (key_sign(id->key, sigp, lenp, data, datalen));
 939         /* load the private key from the file */
 940         if ((prv = load_identity_file(id->filename)) == NULL)
 941                 return (-1);
 942         ret = key_sign(prv, sigp, lenp, data, datalen);
 943         key_free(prv);
 944         return (ret);
 945 }
 946
 947 static int
 948 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
 949 {
 950         Buffer b;
 951         u_char *blob, *signature;
 952         u_int bloblen, slen;
 953         u_int skip = 0;
 954         int ret = -1;
 955         int have_sig = 1;
 956
 957         debug3("sign_and_send_pubkey");
 958
 959         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
 960                 /* we cannot handle this key */
 961                 debug3("sign_and_send_pubkey: cannot handle key");
 962                 return 0;
 963         }
 964         /* data to be signed */
 965         buffer_init(&b);
 966         if (datafellows & SSH_OLD_SESSIONID) {
 967                 buffer_append(&b, session_id2, session_id2_len);
 968                 skip = session_id2_len;
 969         } else {
 970                 buffer_put_string(&b, session_id2, session_id2_len);
 971                 skip = buffer_len(&b);
 972         }
 973         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
 974         buffer_put_cstring(&b, authctxt->server_user);
 975         buffer_put_cstring(&b,
 976             datafellows & SSH_BUG_PKSERVICE ?
 977             "ssh-userauth" :
 978             authctxt->service);
 979         if (datafellows & SSH_BUG_PKAUTH) {
 980                 buffer_put_char(&b, have_sig);
 981         } else {
 982                 buffer_put_cstring(&b, authctxt->method->name);
 983                 buffer_put_char(&b, have_sig);
 984                 buffer_put_cstring(&b, key_ssh_name(id->key));
 985         }
 986         buffer_put_string(&b, blob, bloblen);
 987
 988         /* generate signature */
 989         ret = identity_sign(id, &signature, &slen,
 990             buffer_ptr(&b), buffer_len(&b));
 991         if (ret == -1) {
 992                 xfree(blob);
 993                 buffer_free(&b);
 994                 return 0;
 995         }
 996 #ifdef DEBUG_PK
 997         buffer_dump(&b);
 998 #endif
 999         if (datafellows & SSH_BUG_PKSERVICE) {
1000                 buffer_clear(&b);
1001                 buffer_append(&b, session_id2, session_id2_len);
1002                 skip = session_id2_len;
1003                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1004                 buffer_put_cstring(&b, authctxt->server_user);
1005                 buffer_put_cstring(&b, authctxt->service);
1006                 buffer_put_cstring(&b, authctxt->method->name);
1007                 buffer_put_char(&b, have_sig);
1008                 if (!(datafellows & SSH_BUG_PKAUTH))
1009                         buffer_put_cstring(&b, key_ssh_name(id->key));
1010                 buffer_put_string(&b, blob, bloblen);
1011         }
1012         xfree(blob);
1013
1014         /* append signature */
1015         buffer_put_string(&b, signature, slen);
1016         xfree(signature);
1017
1018         /* skip session id and packet type */
1019         if (buffer_len(&b) < skip + 1)
1020                 fatal("userauth_pubkey: internal error");
1021         buffer_consume(&b, skip + 1);
1022
1023         /* put remaining data from buffer into packet */
1024         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1025         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1026         buffer_free(&b);
1027         packet_send();
1028
1029         return 1;
1030 }
1031
1032 static int
1033 send_pubkey_test(Authctxt *authctxt, Identity *id)
1034 {
1035         u_char *blob;
1036         u_int bloblen, have_sig = 0;
1037
1038         debug3("send_pubkey_test");
1039
1040         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1041                 /* we cannot handle this key */
1042                 debug3("send_pubkey_test: cannot handle key");
1043                 return 0;
1044         }
1045         /* register callback for USERAUTH_PK_OK message */
1046         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1047
1048         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1049         packet_put_cstring(authctxt->server_user);
1050         packet_put_cstring(authctxt->service);
1051         packet_put_cstring(authctxt->method->name);
1052         packet_put_char(have_sig);
1053         if (!(datafellows & SSH_BUG_PKAUTH))
1054                 packet_put_cstring(key_ssh_name(id->key));
1055         packet_put_string(blob, bloblen);
1056         xfree(blob);
1057         packet_send();
1058         return 1;
1059 }
1060
1061 static Key *
1062 load_identity_file(char *filename)
1063 {
1064         Key *private;
1065         char prompt[300], *passphrase;
1066         int quit, i;
1067         struct stat st;
1068
1069         if (stat(filename, &st) < 0) {
1070                 debug3("no such identity: %s", filename);
1071                 return NULL;
1072         }
1073         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL);
1074         if (private == NULL) {
1075                 if (options.batch_mode)
1076                         return NULL;
1077                 snprintf(prompt, sizeof prompt,
1078                     "Enter passphrase for key '%.100s': ", filename);
1079                 for (i = 0; i < options.number_of_password_prompts; i++) {
1080                         passphrase = read_passphrase(prompt, 0);
1081                         if (strcmp(passphrase, "") != 0) {
1082                                 private = key_load_private_type(KEY_UNSPEC, filename,
1083                                     passphrase, NULL);
1084                                 quit = 0;
1085                         } else {
1086                                 debug2("no passphrase given, try next key");
1087                                 quit = 1;
1088                         }
1089                         memset(passphrase, 0, strlen(passphrase));
1090                         xfree(passphrase);
1091                         if (private != NULL || quit)
1092                                 break;
1093                         debug2("bad passphrase given, try again...");
1094                 }
1095         }
1096         return private;
1097 }
1098
1099 /*
1100  * try keys in the following order:
1101  *      1. agent keys that are found in the config file
1102  *      2. other agent keys
1103  *      3. keys that are only listed in the config file
1104  */
1105 static void
1106 pubkey_prepare(Authctxt *authctxt)
1107 {
1108         Identity *id;
1109         Idlist agent, files, *preferred;
1110         Key *key;
1111         AuthenticationConnection *ac;
1112         char *comment;
1113         int i, found;
1114
1115         TAILQ_INIT(&agent);     /* keys from the agent */
1116         TAILQ_INIT(&files);     /* keys from the config file */
1117         preferred = &authctxt->keys;
1118         TAILQ_INIT(preferred);  /* preferred order of keys */
1119
1120         /* list of keys stored in the filesystem */
1121         for (i = 0; i < options.num_identity_files; i++) {
1122                 key = options.identity_keys[i];
1123                 if (key && key->type == KEY_RSA1)
1124                         continue;
1125                 options.identity_keys[i] = NULL;
1126                 id = xmalloc(sizeof(*id));
1127                 memset(id, 0, sizeof(*id));
1128                 id->key = key;
1129                 id->filename = xstrdup(options.identity_files[i]);
1130                 TAILQ_INSERT_TAIL(&files, id, next);
1131         }
1132         /* list of keys supported by the agent */
1133         if ((ac = ssh_get_authentication_connection())) {
1134                 for (key = ssh_get_first_identity(ac, &comment, 2);
1135                     key != NULL;
1136                     key = ssh_get_next_identity(ac, &comment, 2)) {
1137                         found = 0;
1138                         TAILQ_FOREACH(id, &files, next) {
1139                                 /* agent keys from the config file are preferred */
1140                                 if (key_equal(key, id->key)) {
1141                                         key_free(key);
1142                                         xfree(comment);
1143                                         TAILQ_REMOVE(&files, id, next);
1144                                         TAILQ_INSERT_TAIL(preferred, id, next);
1145                                         id->ac = ac;
1146                                         found = 1;
1147                                         break;
1148                                 }
1149                         }
1150                         if (!found && !options.identities_only) {
1151                                 id = xmalloc(sizeof(*id));
1152                                 memset(id, 0, sizeof(*id));
1153                                 id->key = key;
1154                                 id->filename = comment;
1155                                 id->ac = ac;
1156                                 TAILQ_INSERT_TAIL(&agent, id, next);
1157                         }
1158                 }
1159                 /* append remaining agent keys */
1160                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1161                         TAILQ_REMOVE(&agent, id, next);
1162                         TAILQ_INSERT_TAIL(preferred, id, next);
1163                 }
1164                 authctxt->agent = ac;
1165         }
1166         /* append remaining keys from the config file */
1167         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1168                 TAILQ_REMOVE(&files, id, next);
1169                 TAILQ_INSERT_TAIL(preferred, id, next);
1170         }
1171         TAILQ_FOREACH(id, preferred, next) {
1172                 debug2("key: %s (%p)", id->filename, id->key);
1173         }
1174 }
1175
1176 static void
1177 pubkey_cleanup(Authctxt *authctxt)
1178 {
1179         Identity *id;
1180
1181         if (authctxt->agent != NULL)
1182                 ssh_close_authentication_connection(authctxt->agent);
1183         for (id = TAILQ_FIRST(&authctxt->keys); id;
1184             id = TAILQ_FIRST(&authctxt->keys)) {
1185                 TAILQ_REMOVE(&authctxt->keys, id, next);
1186                 if (id->key)
1187                         key_free(id->key);
1188                 if (id->filename)
1189                         xfree(id->filename);
1190                 xfree(id);
1191         }
1192 }
1193
1194 int
1195 userauth_pubkey(Authctxt *authctxt)
1196 {
1197         Identity *id;
1198         int sent = 0;
1199
1200         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1201                 if (id->tried++)
1202                         return (0);
1203                 /* move key to the end of the queue */
1204                 TAILQ_REMOVE(&authctxt->keys, id, next);
1205                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1206                 /*
1207                  * send a test message if we have the public key. for
1208                  * encrypted keys we cannot do this and have to load the
1209                  * private key instead
1210                  */
1211                 if (id->key && id->key->type != KEY_RSA1) {
1212                         debug("Offering public key: %s", id->filename);
1213                         sent = send_pubkey_test(authctxt, id);
1214                 } else if (id->key == NULL) {
1215                         debug("Trying private key: %s", id->filename);
1216                         id->key = load_identity_file(id->filename);
1217                         if (id->key != NULL) {
1218                                 id->isprivate = 1;
1219                                 sent = sign_and_send_pubkey(authctxt, id);
1220                                 key_free(id->key);
1221                                 id->key = NULL;
1222                         }
1223                 }
1224                 if (sent)
1225                         return (sent);
1226         }
1227         return (0);
1228 }
1229
1230 /*
1231  * Send userauth request message specifying keyboard-interactive method.
1232  */
1233 int
1234 userauth_kbdint(Authctxt *authctxt)
1235 {
1236         static int attempt = 0;
1237
1238         if (attempt++ >= options.number_of_password_prompts)
1239                 return 0;
1240         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1241         if (attempt > 1 && !authctxt->info_req_seen) {
1242                 debug3("userauth_kbdint: disable: no info_req_seen");
1243                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1244                 return 0;
1245         }
1246
1247         debug2("userauth_kbdint");
1248         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1249         packet_put_cstring(authctxt->server_user);
1250         packet_put_cstring(authctxt->service);
1251         packet_put_cstring(authctxt->method->name);
1252         packet_put_cstring("");                                 /* lang */
1253         packet_put_cstring(options.kbd_interactive_devices ?
1254             options.kbd_interactive_devices : "");
1255         packet_send();
1256
1257         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1258         return 1;
1259 }
1260
1261 /*
1262  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1263  */
1264 void
1265 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1266 {
1267         Authctxt *authctxt = ctxt;
1268         char *name, *inst, *lang, *prompt, *response;
1269         u_int num_prompts, i;
1270         int echo = 0;
1271
1272         debug2("input_userauth_info_req");
1273
1274         if (authctxt == NULL)
1275                 fatal("input_userauth_info_req: no authentication context");
1276
1277         authctxt->info_req_seen = 1;
1278
1279         name = packet_get_string(NULL);
1280         inst = packet_get_string(NULL);
1281         lang = packet_get_string(NULL);
1282         if (strlen(name) > 0)
1283                 logit("%s", name);
1284         if (strlen(inst) > 0)
1285                 logit("%s", inst);
1286         xfree(name);
1287         xfree(inst);
1288         xfree(lang);
1289
1290         num_prompts = packet_get_int();
1291         /*
1292          * Begin to build info response packet based on prompts requested.
1293          * We commit to providing the correct number of responses, so if
1294          * further on we run into a problem that prevents this, we have to
1295          * be sure and clean this up and send a correct error response.
1296          */
1297         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1298         packet_put_int(num_prompts);
1299
1300         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1301         for (i = 0; i < num_prompts; i++) {
1302                 prompt = packet_get_string(NULL);
1303                 echo = packet_get_char();
1304
1305                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1306
1307                 packet_put_cstring(response);
1308                 memset(response, 0, strlen(response));
1309                 xfree(response);
1310                 xfree(prompt);
1311         }
1312         packet_check_eom(); /* done with parsing incoming message. */
1313
1314         packet_add_padding(64);
1315         packet_send();
1316 }
1317
1318 static int
1319 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1320     u_char *data, u_int datalen)
1321 {
1322         Buffer b;
1323         struct stat st;
1324         pid_t pid;
1325         int to[2], from[2], status, version = 2;
1326
1327         debug2("ssh_keysign called");
1328
1329         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1330                 error("ssh_keysign: no installed: %s", strerror(errno));
1331                 return -1;
1332         }
1333         if (fflush(stdout) != 0)
1334                 error("ssh_keysign: fflush: %s", strerror(errno));
1335         if (pipe(to) < 0) {
1336                 error("ssh_keysign: pipe: %s", strerror(errno));
1337                 return -1;
1338         }
1339         if (pipe(from) < 0) {
1340                 error("ssh_keysign: pipe: %s", strerror(errno));
1341                 return -1;
1342         }
1343         if ((pid = fork()) < 0) {
1344                 error("ssh_keysign: fork: %s", strerror(errno));
1345                 return -1;
1346         }
1347         if (pid == 0) {
1348                 seteuid(getuid());
1349                 setuid(getuid());
1350                 close(from[0]);
1351                 if (dup2(from[1], STDOUT_FILENO) < 0)
1352                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1353                 close(to[1]);
1354                 if (dup2(to[0], STDIN_FILENO) < 0)
1355                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1356                 close(from[1]);
1357                 close(to[0]);
1358                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1359                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1360                     strerror(errno));
1361         }
1362         close(from[1]);
1363         close(to[0]);
1364
1365         buffer_init(&b);
1366         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1367         buffer_put_string(&b, data, datalen);
1368         if (ssh_msg_send(to[1], version, &b) == -1)
1369                 fatal("ssh_keysign: couldn't send request");
1370
1371         if (ssh_msg_recv(from[0], &b) < 0) {
1372                 error("ssh_keysign: no reply");
1373                 buffer_free(&b);
1374                 return -1;
1375         }
1376         close(from[0]);
1377         close(to[1]);
1378
1379         while (waitpid(pid, &status, 0) < 0)
1380                 if (errno != EINTR)
1381                         break;
1382
1383         if (buffer_get_char(&b) != version) {
1384                 error("ssh_keysign: bad version");
1385                 buffer_free(&b);
1386                 return -1;
1387         }
1388         *sigp = buffer_get_string(&b, lenp);
1389         buffer_free(&b);
1390
1391         return 0;
1392 }
1393
1394 int
1395 userauth_hostbased(Authctxt *authctxt)
1396 {
1397         Key *private = NULL;
1398         Sensitive *sensitive = authctxt->sensitive;
1399         Buffer b;
1400         u_char *signature, *blob;
1401         char *chost, *pkalg, *p;
1402         const char *service;
1403         u_int blen, slen;
1404         int ok, i, len, found = 0;
1405
1406         /* check for a useful key */
1407         for (i = 0; i < sensitive->nkeys; i++) {
1408                 private = sensitive->keys[i];
1409                 if (private && private->type != KEY_RSA1) {
1410                         found = 1;
1411                         /* we take and free the key */
1412                         sensitive->keys[i] = NULL;
1413                         break;
1414                 }
1415         }
1416         if (!found) {
1417                 debug("No more client hostkeys for hostbased authentication.");
1418                 return 0;
1419         }
1420         if (key_to_blob(private, &blob, &blen) == 0) {
1421                 key_free(private);
1422                 return 0;
1423         }
1424         /* figure out a name for the client host */
1425         p = get_local_name(packet_get_connection_in());
1426         if (p == NULL) {
1427                 error("userauth_hostbased: cannot get local ipaddr/name");
1428                 key_free(private);
1429                 return 0;
1430         }
1431         len = strlen(p) + 2;
1432         chost = xmalloc(len);
1433         strlcpy(chost, p, len);
1434         strlcat(chost, ".", len);
1435         debug2("userauth_hostbased: chost %s", chost);
1436         xfree(p);
1437
1438         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1439             authctxt->service;
1440         pkalg = xstrdup(key_ssh_name(private));
1441         buffer_init(&b);
1442         /* construct data */
1443         buffer_put_string(&b, session_id2, session_id2_len);
1444         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1445         buffer_put_cstring(&b, authctxt->server_user);
1446         buffer_put_cstring(&b, service);
1447         buffer_put_cstring(&b, authctxt->method->name);
1448         buffer_put_cstring(&b, pkalg);
1449         buffer_put_string(&b, blob, blen);
1450         buffer_put_cstring(&b, chost);
1451         buffer_put_cstring(&b, authctxt->local_user);
1452 #ifdef DEBUG_PK
1453         buffer_dump(&b);
1454 #endif
1455         if (sensitive->external_keysign)
1456                 ok = ssh_keysign(private, &signature, &slen,
1457                     buffer_ptr(&b), buffer_len(&b));
1458         else
1459                 ok = key_sign(private, &signature, &slen,
1460                     buffer_ptr(&b), buffer_len(&b));
1461         key_free(private);
1462         buffer_free(&b);
1463         if (ok != 0) {
1464                 error("key_sign failed");
1465                 xfree(chost);
1466                 xfree(pkalg);
1467                 return 0;
1468         }
1469         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1470         packet_put_cstring(authctxt->server_user);
1471         packet_put_cstring(authctxt->service);
1472         packet_put_cstring(authctxt->method->name);
1473         packet_put_cstring(pkalg);
1474         packet_put_string(blob, blen);
1475         packet_put_cstring(chost);
1476         packet_put_cstring(authctxt->local_user);
1477         packet_put_string(signature, slen);
1478         memset(signature, 's', slen);
1479         xfree(signature);
1480         xfree(chost);
1481         xfree(pkalg);
1482
1483         packet_send();
1484         return 1;
1485 }
1486
1487 /* find auth method */
1488
1489 /*
1490  * given auth method name, if configurable options permit this method fill
1491  * in auth_ident field and return true, otherwise return false.
1492  */
1493 static int
1494 authmethod_is_enabled(Authmethod *method)
1495 {
1496         if (method == NULL)
1497                 return 0;
1498         /* return false if options indicate this method is disabled */
1499         if  (method->enabled == NULL || *method->enabled == 0)
1500                 return 0;
1501         /* return false if batch mode is enabled but method needs interactive mode */
1502         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1503                 return 0;
1504         return 1;
1505 }
1506
1507 static Authmethod *
1508 authmethod_lookup(const char *name)
1509 {
1510         Authmethod *method = NULL;
1511         if (name != NULL)
1512                 for (method = authmethods; method->name != NULL; method++)
1513                         if (strcmp(name, method->name) == 0)
1514                                 return method;
1515         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1516         return NULL;
1517 }
1518
1519 /* XXX internal state */
1520 static Authmethod *current = NULL;
1521 static char *supported = NULL;
1522 static char *preferred = NULL;
1523
1524 /*
1525  * Given the authentication method list sent by the server, return the
1526  * next method we should try.  If the server initially sends a nil list,
1527  * use a built-in default list.
1528  */
1529 static Authmethod *
1530 authmethod_get(char *authlist)
1531 {
1532         char *name = NULL;
1533         u_int next;
1534
1535         /* Use a suitable default if we're passed a nil list.  */
1536         if (authlist == NULL || strlen(authlist) == 0)
1537                 authlist = options.preferred_authentications;
1538
1539         if (supported == NULL || strcmp(authlist, supported) != 0) {
1540                 debug3("start over, passed a different list %s", authlist);
1541                 if (supported != NULL)
1542                         xfree(supported);
1543                 supported = xstrdup(authlist);
1544                 preferred = options.preferred_authentications;
1545                 debug3("preferred %s", preferred);
1546                 current = NULL;
1547         } else if (current != NULL && authmethod_is_enabled(current))
1548                 return current;
1549
1550         for (;;) {
1551                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1552                         debug("No more authentication methods to try.");
1553                         current = NULL;
1554                         return NULL;
1555                 }
1556                 preferred += next;
1557                 debug3("authmethod_lookup %s", name);
1558                 debug3("remaining preferred: %s", preferred);
1559                 if ((current = authmethod_lookup(name)) != NULL &&
1560                     authmethod_is_enabled(current)) {
1561                         debug3("authmethod_is_enabled %s", name);
1562                         debug("Next authentication method: %s", name);
1563                         return current;
1564                 }
1565         }
1566 }
1567
1568 static char *
1569 authmethods_get(void)
1570 {
1571         Authmethod *method = NULL;
1572         Buffer b;
1573         char *list;
1574
1575         buffer_init(&b);
1576         for (method = authmethods; method->name != NULL; method++) {
1577                 if (authmethod_is_enabled(method)) {
1578                         if (buffer_len(&b) > 0)
1579                                 buffer_append(&b, ",", 1);
1580                         buffer_append(&b, method->name, strlen(method->name));
1581                 }
1582         }
1583         buffer_append(&b, "\0", 1);
1584         list = xstrdup(buffer_ptr(&b));
1585         buffer_free(&b);
1586         return list;
1587 }