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 1.134 2004/01/19 21:25:15 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 static int gssapi_with_mic = 1; /* flag to toggle "gssapi-with-mic" vs.
 271                                    "gssapi" */
 272
 273 Authmethod authmethods[] = {
 274 #ifdef GSSAPI
 275         {"external-keyx",
 276                 userauth_external,
 277                 &options.gss_authentication,
 278                 NULL},
 279         {"gssapi-with-mic",
 280                 userauth_gssapi_with_mic,
 281                 &options.gss_authentication,
 282                 NULL},
 283         {"gssapi",
 284                 userauth_gssapi_without_mic,
 285                 &options.gss_authentication,
 286                 NULL},
 287 #endif
 288         {"hostbased",
 289                 userauth_hostbased,
 290                 &options.hostbased_authentication,
 291                 NULL},
 292         {"publickey",
 293                 userauth_pubkey,
 294                 &options.pubkey_authentication,
 295                 NULL},
 296         {"keyboard-interactive",
 297                 userauth_kbdint,
 298                 &options.kbd_interactive_authentication,
 299                 &options.batch_mode},
 300         {"password",
 301                 userauth_passwd,
 302                 &options.password_authentication,
 303                 &options.batch_mode},
 304         {"none",
 305                 userauth_none,
 306                 NULL,
 307                 NULL},
 308         {NULL, NULL, NULL, NULL}
 309 };
 310
 311 void
 312 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 313     Sensitive *sensitive)
 314 {
 315         Authctxt authctxt;
 316         int type;
 317
 318         if (options.challenge_response_authentication)
 319                 options.kbd_interactive_authentication = 1;
 320
 321         packet_start(SSH2_MSG_SERVICE_REQUEST);
 322         packet_put_cstring("ssh-userauth");
 323         packet_send();
 324         debug("SSH2_MSG_SERVICE_REQUEST sent");
 325         packet_write_wait();
 326         type = packet_read();
 327         if (type != SSH2_MSG_SERVICE_ACCEPT)
 328                 fatal("Server denied authentication request: %d", type);
 329         if (packet_remaining() > 0) {
 330                 char *reply = packet_get_string(NULL);
 331                 debug2("service_accept: %s", reply);
 332                 xfree(reply);
 333         } else {
 334                 debug2("buggy server: service_accept w/o service");
 335         }
 336         packet_check_eom();
 337         debug("SSH2_MSG_SERVICE_ACCEPT received");
 338
 339         if (options.preferred_authentications == NULL)
 340                 options.preferred_authentications = authmethods_get();
 341
 342         /* setup authentication context */
 343         memset(&authctxt, 0, sizeof(authctxt));
 344         pubkey_prepare(&authctxt);
 345         authctxt.server_user = server_user;
 346         authctxt.local_user = local_user;
 347         authctxt.host = host;
 348         authctxt.service = "ssh-connection";            /* service name */
 349         authctxt.success = 0;
 350         authctxt.method = authmethod_lookup("none");
 351         authctxt.authlist = NULL;
 352         authctxt.methoddata = NULL;
 353         authctxt.sensitive = sensitive;
 354         authctxt.info_req_seen = 0;
 355         if (authctxt.method == NULL)
 356                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 357
 358         /* initial userauth request */
 359         userauth_none(&authctxt);
 360
 361         dispatch_init(&input_userauth_error);
 362         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 363         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 364         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 365         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 366
 367         pubkey_cleanup(&authctxt);
 368         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 369
 370         debug("Authentication succeeded (%s).", authctxt.method->name);
 371 }
 372
 373 void
 374 userauth(Authctxt *authctxt, char *authlist)
 375 {
 376         if (authctxt->methoddata) {
 377                 xfree(authctxt->methoddata);
 378                 authctxt->methoddata = NULL;
 379         }
 380         if (authlist == NULL) {
 381                 authlist = authctxt->authlist;
 382         } else {
 383                 if (authctxt->authlist)
 384                         xfree(authctxt->authlist);
 385                 authctxt->authlist = authlist;
 386         }
 387         for (;;) {
 388                 Authmethod *method = authmethod_get(authlist);
 389                 if (method == NULL)
 390                         fatal("Permission denied (%s).", authlist);
 391                 authctxt->method = method;
 392
 393                 /* reset the per method handler */
 394                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 395                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 396
 397                 /* and try new method */
 398                 if (method->userauth(authctxt) != 0) {
 399                         debug2("we sent a %s packet, wait for reply", method->name);
 400                         break;
 401                 } else {
 402                         debug2("we did not send a packet, disable method");
 403                         method->enabled = NULL;
 404                 }
 405         }
 406 }
 407
 408 void
 409 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 410 {
 411         fatal("input_userauth_error: bad message during authentication: "
 412            "type %d", type);
 413 }
 414
 415 void
 416 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 417 {
 418         char *msg, *lang;
 419
 420         debug3("input_userauth_banner");
 421         msg = packet_get_string(NULL);
 422         lang = packet_get_string(NULL);
 423         if (options.log_level > SYSLOG_LEVEL_QUIET)
 424                 fprintf(stderr, "%s", msg);
 425         xfree(msg);
 426         xfree(lang);
 427 }
 428
 429 void
 430 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 431 {
 432         Authctxt *authctxt = ctxt;
 433         if (authctxt == NULL)
 434                 fatal("input_userauth_success: no authentication context");
 435         if (authctxt->authlist) {
 436                 xfree(authctxt->authlist);
 437                 authctxt->authlist = NULL;
 438         }
 439         if (authctxt->methoddata) {
 440                 xfree(authctxt->methoddata);
 441                 authctxt->methoddata = NULL;
 442         }
 443         authctxt->success = 1;                  /* break out */
 444 }
 445
 446 void
 447 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 448 {
 449         Authctxt *authctxt = ctxt;
 450         char *authlist = NULL;
 451         int partial;
 452
 453         if (authctxt == NULL)
 454                 fatal("input_userauth_failure: no authentication context");
 455
 456         authlist = packet_get_string(NULL);
 457         partial = packet_get_char();
 458         packet_check_eom();
 459
 460         if (partial != 0)
 461                 logit("Authenticated with partial success.");
 462         debug("Authentications that can continue: %s", authlist);
 463
 464         userauth(authctxt, authlist);
 465 }
 466 void
 467 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 468 {
 469         Authctxt *authctxt = ctxt;
 470         Key *key = NULL;
 471         Identity *id = NULL;
 472         Buffer b;
 473         int pktype, sent = 0;
 474         u_int alen, blen;
 475         char *pkalg, *fp;
 476         u_char *pkblob;
 477
 478         if (authctxt == NULL)
 479                 fatal("input_userauth_pk_ok: no authentication context");
 480         if (datafellows & SSH_BUG_PKOK) {
 481                 /* this is similar to SSH_BUG_PKAUTH */
 482                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 483                 pkblob = packet_get_string(&blen);
 484                 buffer_init(&b);
 485                 buffer_append(&b, pkblob, blen);
 486                 pkalg = buffer_get_string(&b, &alen);
 487                 buffer_free(&b);
 488         } else {
 489                 pkalg = packet_get_string(&alen);
 490                 pkblob = packet_get_string(&blen);
 491         }
 492         packet_check_eom();
 493
 494         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 495
 496         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 497                 debug("unknown pkalg %s", pkalg);
 498                 goto done;
 499         }
 500         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 501                 debug("no key from blob. pkalg %s", pkalg);
 502                 goto done;
 503         }
 504         if (key->type != pktype) {
 505                 error("input_userauth_pk_ok: type mismatch "
 506                     "for decoded key (received %d, expected %d)",
 507                     key->type, pktype);
 508                 goto done;
 509         }
 510         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 511         debug2("input_userauth_pk_ok: fp %s", fp);
 512         xfree(fp);
 513
 514         /*
 515          * search keys in the reverse order, because last candidate has been
 516          * moved to the end of the queue.  this also avoids confusion by
 517          * duplicate keys
 518          */
 519         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, next, idlist) {
 520                 if (key_equal(key, id->key)) {
 521                         sent = sign_and_send_pubkey(authctxt, id);
 522                         break;
 523                 }
 524         }
 525 done:
 526         if (key != NULL)
 527                 key_free(key);
 528         xfree(pkalg);
 529         xfree(pkblob);
 530
 531         /* try another method if we did not send a packet */
 532         if (sent == 0)
 533                 userauth(authctxt, NULL);
 534 }
 535
 536 #ifdef GSSAPI
 537 int
 538 userauth_gssapi(Authctxt *authctxt)
 539 {
 540         Gssctxt *gssctxt = NULL;
 541         static gss_OID_set gss_supported = NULL;
 542         static int mech = 0;
 543         OM_uint32 min;
 544         int ok = 0;
 545
 546         if (!options.gss_authentication) {
 547                 verbose("GSSAPI authentication disabled.");
 548                 return 0;
 549         }
 550
 551         /* Try one GSSAPI method at a time, rather than sending them all at
 552          * once. */
 553
 554         if (gss_supported == NULL)
 555                 gss_indicate_mechs(&min, &gss_supported);
 556
 557         /* Check to see if the mechanism is usable before we offer it */
 558         while (mech < gss_supported->count && !ok) {
 559                 if (gssctxt)
 560                         ssh_gssapi_delete_ctx(&gssctxt);
 561                 ssh_gssapi_build_ctx(&gssctxt);
 562                 ssh_gssapi_set_oid(gssctxt, &gss_supported->elements[mech]);
 563
 564                 /* My DER encoding requires length<128 */
 565                 if (gss_supported->elements[mech].length < 128 &&
 566                     !GSS_ERROR(ssh_gssapi_import_name(gssctxt,
 567                     authctxt->host))) {
 568                         ok = 1; /* Mechanism works */
 569                 } else {
 570                         mech++;
 571                 }
 572         }
 573
 574         if (!ok) return 0;
 575
 576         authctxt->methoddata=(void *)gssctxt;
 577
 578         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 579         packet_put_cstring(authctxt->server_user);
 580         packet_put_cstring(authctxt->service);
 581         packet_put_cstring(authctxt->method->name);
 582
 583         packet_put_int(1);
 584
 585         /* Some servers encode the OID incorrectly (as we used to) */
 586         if (datafellows & SSH_BUG_GSSAPI_BER) {
 587                 packet_put_string(gss_supported->elements[mech].elements,
 588                     gss_supported->elements[mech].length);
 589         } else {
 590                 packet_put_int((gss_supported->elements[mech].length)+2);
 591                 packet_put_char(SSH_GSS_OIDTYPE);
 592                 packet_put_char(gss_supported->elements[mech].length);
 593                 packet_put_raw(gss_supported->elements[mech].elements,
 594                     gss_supported->elements[mech].length);
 595         }
 596
 597         packet_send();
 598
 599         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 600         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 601         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 602         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 603
 604         mech++; /* Move along to next candidate */
 605
 606         return 1;
 607 }
 608
 609 int
 610 userauth_gssapi_with_mic(Authctxt *authctxt)
 611 {
 612     gssapi_with_mic = 1;
 613     return userauth_gssapi(authctxt);
 614 }
 615
 616 int
 617 userauth_gssapi_without_mic(Authctxt *authctxt)
 618 {
 619     gssapi_with_mic = 0;
 620     return userauth_gssapi(authctxt);
 621 }
 622
 623 static OM_uint32
 624 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 625 {
 626         Authctxt *authctxt = ctxt;
 627         Gssctxt *gssctxt = authctxt->methoddata;
 628         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 629         gss_buffer_desc gssbuf, mic;
 630         OM_uint32 status, ms, flags;
 631         Buffer b;
 632
 633         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 634             recv_tok, &send_tok, &flags);
 635
 636         if (send_tok.length > 0) {
 637                 if (GSS_ERROR(status))
 638                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 639                 else
 640                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 641
 642                 packet_put_string(send_tok.value, send_tok.length);
 643                 packet_send();
 644                 gss_release_buffer(&ms, &send_tok);
 645         }
 646
 647         if (status == GSS_S_COMPLETE) {
 648                 /* send either complete or MIC, depending on mechanism */
 649                 if (!(flags & GSS_C_INTEG_FLAG) || !gssapi_with_mic) {
 650                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 651                         packet_send();
 652                 } else {
 653                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 654                             authctxt->service, "gssapi-with-mic");
 655
 656                         gssbuf.value = buffer_ptr(&b);
 657                         gssbuf.length = buffer_len(&b);
 658
 659                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 660
 661                         if (!GSS_ERROR(status)) {
 662                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 663                                 packet_put_string(mic.value, mic.length);
 664
 665                                 packet_send();
 666                         }
 667
 668                         buffer_free(&b);
 669                         gss_release_buffer(&ms, &mic);
 670                 }
 671         }
 672
 673         return status;
 674 }
 675
 676 void
 677 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 678 {
 679         Authctxt *authctxt = ctxt;
 680         Gssctxt *gssctxt;
 681         int oidlen;
 682         char *oidv;
 683
 684         if (authctxt == NULL)
 685                 fatal("input_gssapi_response: no authentication context");
 686         gssctxt = authctxt->methoddata;
 687
 688         /* Setup our OID */
 689         oidv = packet_get_string(&oidlen);
 690
 691         if (datafellows & SSH_BUG_GSSAPI_BER) {
 692                 if (!ssh_gssapi_check_oid(gssctxt, oidv, oidlen))
 693                         fatal("Server returned different OID than expected");
 694         } else {
 695                 if(oidv[0] != SSH_GSS_OIDTYPE || oidv[1] != oidlen-2) {
 696                         debug("Badly encoded mechanism OID received");
 697                         userauth(authctxt, NULL);
 698                         xfree(oidv);
 699                         return;
 700                 }
 701                 if (!ssh_gssapi_check_oid(gssctxt, oidv+2, oidlen-2))
 702                         fatal("Server returned different OID than expected");
 703         }
 704
 705         packet_check_eom();
 706
 707         xfree(oidv);
 708
 709         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 710                 /* Start again with next method on list */
 711                 debug("Trying to start again");
 712                 userauth(authctxt, NULL);
 713                 return;
 714         }
 715 }
 716
 717 void
 718 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 719 {
 720         Authctxt *authctxt = ctxt;
 721         gss_buffer_desc recv_tok;
 722         OM_uint32 status;
 723         u_int slen;
 724
 725         if (authctxt == NULL)
 726                 fatal("input_gssapi_response: no authentication context");
 727
 728         recv_tok.value = packet_get_string(&slen);
 729         recv_tok.length = slen; /* safe typecast */
 730
 731         packet_check_eom();
 732
 733         status = process_gssapi_token(ctxt, &recv_tok);
 734
 735         xfree(recv_tok.value);
 736
 737         if (GSS_ERROR(status)) {
 738                 /* Start again with the next method in the list */
 739                 userauth(authctxt, NULL);
 740                 return;
 741         }
 742 }
 743
 744 void
 745 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 746 {
 747         Authctxt *authctxt = ctxt;
 748         Gssctxt *gssctxt;
 749         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 750         gss_buffer_desc recv_tok;
 751         OM_uint32 status, ms;
 752         u_int len;
 753
 754         if (authctxt == NULL)
 755                 fatal("input_gssapi_response: no authentication context");
 756         gssctxt = authctxt->methoddata;
 757
 758         recv_tok.value = packet_get_string(&len);
 759         recv_tok.length = len;
 760
 761         packet_check_eom();
 762
 763         /* Stick it into GSSAPI and see what it says */
 764         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 765                                      &recv_tok, &send_tok, NULL);
 766
 767         xfree(recv_tok.value);
 768         gss_release_buffer(&ms, &send_tok);
 769
 770         /* Server will be returning a failed packet after this one */
 771 }
 772
 773 void
 774 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 775 {
 776         OM_uint32 maj, min;
 777         char *msg;
 778         char *lang;
 779
 780         maj=packet_get_int();
 781         min=packet_get_int();
 782         msg=packet_get_string(NULL);
 783         lang=packet_get_string(NULL);
 784
 785         packet_check_eom();
 786
 787         debug("Server GSSAPI Error:\n%s\n", msg);
 788         xfree(msg);
 789         xfree(lang);
 790 }
 791
 792 int
 793 userauth_external(Authctxt *authctxt)
 794 {
 795         static int attempt = 0;
 796
 797         if (attempt++ >= 1)
 798                 return 0;
 799
 800         /* The client MUST NOT try this method if initial key exchange
 801            was not performed using a GSSAPI-based key exchange
 802            method. */
 803         if (xxx_kex->kex_type != KEX_GSS_GRP1_SHA1) {
 804                 debug2("gsskex not performed, skipping external-keyx");
 805                 return 0;
 806         }
 807
 808         debug2("userauth_external");
 809         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 810 #ifdef GSI
 811         if(options.implicit && !(datafellows & SSH_BUG_GSS_EMPTYUSER)) {
 812             packet_put_cstring("");
 813         } else {
 814 #endif
 815             packet_put_cstring(authctxt->server_user);
 816 #ifdef GSI
 817         }
 818 #endif
 819         packet_put_cstring(authctxt->service);
 820         packet_put_cstring(authctxt->method->name);
 821         packet_send();
 822         packet_write_wait();
 823         return 1;
 824 }
 825 #endif /* GSSAPI */
 826
 827 int
 828 userauth_none(Authctxt *authctxt)
 829 {
 830         /* initial userauth request */
 831         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 832         packet_put_cstring(authctxt->server_user);
 833         packet_put_cstring(authctxt->service);
 834         packet_put_cstring(authctxt->method->name);
 835         packet_send();
 836         return 1;
 837 }
 838
 839 int
 840 userauth_passwd(Authctxt *authctxt)
 841 {
 842         static int attempt = 0;
 843         char prompt[150];
 844         char *password;
 845
 846         if (attempt++ >= options.number_of_password_prompts)
 847                 return 0;
 848
 849         if (attempt != 1)
 850                 error("Permission denied, please try again.");
 851
 852         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 853             authctxt->server_user, authctxt->host);
 854         password = read_passphrase(prompt, 0);
 855         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 856         packet_put_cstring(authctxt->server_user);
 857         packet_put_cstring(authctxt->service);
 858         packet_put_cstring(authctxt->method->name);
 859         packet_put_char(0);
 860         packet_put_cstring(password);
 861         memset(password, 0, strlen(password));
 862         xfree(password);
 863         packet_add_padding(64);
 864         packet_send();
 865
 866         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 867             &input_userauth_passwd_changereq);
 868
 869         return 1;
 870 }
 871 /*
 872  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 873  */
 874 void
 875 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 876 {
 877         Authctxt *authctxt = ctxt;
 878         char *info, *lang, *password = NULL, *retype = NULL;
 879         char prompt[150];
 880
 881         debug2("input_userauth_passwd_changereq");
 882
 883         if (authctxt == NULL)
 884                 fatal("input_userauth_passwd_changereq: "
 885                     "no authentication context");
 886
 887         info = packet_get_string(NULL);
 888         lang = packet_get_string(NULL);
 889         if (strlen(info) > 0)
 890                 logit("%s", info);
 891         xfree(info);
 892         xfree(lang);
 893         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 894         packet_put_cstring(authctxt->server_user);
 895         packet_put_cstring(authctxt->service);
 896         packet_put_cstring(authctxt->method->name);
 897         packet_put_char(1);                     /* additional info */
 898         snprintf(prompt, sizeof(prompt),
 899             "Enter %.30s@%.128s's old password: ",
 900             authctxt->server_user, authctxt->host);
 901         password = read_passphrase(prompt, 0);
 902         packet_put_cstring(password);
 903         memset(password, 0, strlen(password));
 904         xfree(password);
 905         password = NULL;
 906         while (password == NULL) {
 907                 snprintf(prompt, sizeof(prompt),
 908                     "Enter %.30s@%.128s's new password: ",
 909                     authctxt->server_user, authctxt->host);
 910                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 911                 if (password == NULL) {
 912                         /* bail out */
 913                         return;
 914                 }
 915                 snprintf(prompt, sizeof(prompt),
 916                     "Retype %.30s@%.128s's new password: ",
 917                     authctxt->server_user, authctxt->host);
 918                 retype = read_passphrase(prompt, 0);
 919                 if (strcmp(password, retype) != 0) {
 920                         memset(password, 0, strlen(password));
 921                         xfree(password);
 922                         logit("Mismatch; try again, EOF to quit.");
 923                         password = NULL;
 924                 }
 925                 memset(retype, 0, strlen(retype));
 926                 xfree(retype);
 927         }
 928         packet_put_cstring(password);
 929         memset(password, 0, strlen(password));
 930         xfree(password);
 931         packet_add_padding(64);
 932         packet_send();
 933
 934         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 935             &input_userauth_passwd_changereq);
 936 }
 937
 938 static int
 939 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
 940     u_char *data, u_int datalen)
 941 {
 942         Key *prv;
 943         int ret;
 944
 945         /* the agent supports this key */
 946         if (id->ac)
 947                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
 948                     data, datalen));
 949         /*
 950          * we have already loaded the private key or
 951          * the private key is stored in external hardware
 952          */
 953         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
 954                 return (key_sign(id->key, sigp, lenp, data, datalen));
 955         /* load the private key from the file */
 956         if ((prv = load_identity_file(id->filename)) == NULL)
 957                 return (-1);
 958         ret = key_sign(prv, sigp, lenp, data, datalen);
 959         key_free(prv);
 960         return (ret);
 961 }
 962
 963 static int
 964 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
 965 {
 966         Buffer b;
 967         u_char *blob, *signature;
 968         u_int bloblen, slen;
 969         u_int skip = 0;
 970         int ret = -1;
 971         int have_sig = 1;
 972
 973         debug3("sign_and_send_pubkey");
 974
 975         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
 976                 /* we cannot handle this key */
 977                 debug3("sign_and_send_pubkey: cannot handle key");
 978                 return 0;
 979         }
 980         /* data to be signed */
 981         buffer_init(&b);
 982         if (datafellows & SSH_OLD_SESSIONID) {
 983                 buffer_append(&b, session_id2, session_id2_len);
 984                 skip = session_id2_len;
 985         } else {
 986                 buffer_put_string(&b, session_id2, session_id2_len);
 987                 skip = buffer_len(&b);
 988         }
 989         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
 990         buffer_put_cstring(&b, authctxt->server_user);
 991         buffer_put_cstring(&b,
 992             datafellows & SSH_BUG_PKSERVICE ?
 993             "ssh-userauth" :
 994             authctxt->service);
 995         if (datafellows & SSH_BUG_PKAUTH) {
 996                 buffer_put_char(&b, have_sig);
 997         } else {
 998                 buffer_put_cstring(&b, authctxt->method->name);
 999                 buffer_put_char(&b, have_sig);
1000                 buffer_put_cstring(&b, key_ssh_name(id->key));
1001         }
1002         buffer_put_string(&b, blob, bloblen);
1003
1004         /* generate signature */
1005         ret = identity_sign(id, &signature, &slen,
1006             buffer_ptr(&b), buffer_len(&b));
1007         if (ret == -1) {
1008                 xfree(blob);
1009                 buffer_free(&b);
1010                 return 0;
1011         }
1012 #ifdef DEBUG_PK
1013         buffer_dump(&b);
1014 #endif
1015         if (datafellows & SSH_BUG_PKSERVICE) {
1016                 buffer_clear(&b);
1017                 buffer_append(&b, session_id2, session_id2_len);
1018                 skip = session_id2_len;
1019                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1020                 buffer_put_cstring(&b, authctxt->server_user);
1021                 buffer_put_cstring(&b, authctxt->service);
1022                 buffer_put_cstring(&b, authctxt->method->name);
1023                 buffer_put_char(&b, have_sig);
1024                 if (!(datafellows & SSH_BUG_PKAUTH))
1025                         buffer_put_cstring(&b, key_ssh_name(id->key));
1026                 buffer_put_string(&b, blob, bloblen);
1027         }
1028         xfree(blob);
1029
1030         /* append signature */
1031         buffer_put_string(&b, signature, slen);
1032         xfree(signature);
1033
1034         /* skip session id and packet type */
1035         if (buffer_len(&b) < skip + 1)
1036                 fatal("userauth_pubkey: internal error");
1037         buffer_consume(&b, skip + 1);
1038
1039         /* put remaining data from buffer into packet */
1040         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1041         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1042         buffer_free(&b);
1043         packet_send();
1044
1045         return 1;
1046 }
1047
1048 static int
1049 send_pubkey_test(Authctxt *authctxt, Identity *id)
1050 {
1051         u_char *blob;
1052         u_int bloblen, have_sig = 0;
1053
1054         debug3("send_pubkey_test");
1055
1056         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1057                 /* we cannot handle this key */
1058                 debug3("send_pubkey_test: cannot handle key");
1059                 return 0;
1060         }
1061         /* register callback for USERAUTH_PK_OK message */
1062         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1063
1064         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1065         packet_put_cstring(authctxt->server_user);
1066         packet_put_cstring(authctxt->service);
1067         packet_put_cstring(authctxt->method->name);
1068         packet_put_char(have_sig);
1069         if (!(datafellows & SSH_BUG_PKAUTH))
1070                 packet_put_cstring(key_ssh_name(id->key));
1071         packet_put_string(blob, bloblen);
1072         xfree(blob);
1073         packet_send();
1074         return 1;
1075 }
1076
1077 static Key *
1078 load_identity_file(char *filename)
1079 {
1080         Key *private;
1081         char prompt[300], *passphrase;
1082         int quit, i;
1083         struct stat st;
1084
1085         if (stat(filename, &st) < 0) {
1086                 debug3("no such identity: %s", filename);
1087                 return NULL;
1088         }
1089         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL);
1090         if (private == NULL) {
1091                 if (options.batch_mode)
1092                         return NULL;
1093                 snprintf(prompt, sizeof prompt,
1094                     "Enter passphrase for key '%.100s': ", filename);
1095                 for (i = 0; i < options.number_of_password_prompts; i++) {
1096                         passphrase = read_passphrase(prompt, 0);
1097                         if (strcmp(passphrase, "") != 0) {
1098                                 private = key_load_private_type(KEY_UNSPEC, filename,
1099                                     passphrase, NULL);
1100                                 quit = 0;
1101                         } else {
1102                                 debug2("no passphrase given, try next key");
1103                                 quit = 1;
1104                         }
1105                         memset(passphrase, 0, strlen(passphrase));
1106                         xfree(passphrase);
1107                         if (private != NULL || quit)
1108                                 break;
1109                         debug2("bad passphrase given, try again...");
1110                 }
1111         }
1112         return private;
1113 }
1114
1115 /*
1116  * try keys in the following order:
1117  *      1. agent keys that are found in the config file
1118  *      2. other agent keys
1119  *      3. keys that are only listed in the config file
1120  */
1121 static void
1122 pubkey_prepare(Authctxt *authctxt)
1123 {
1124         Identity *id;
1125         Idlist agent, files, *preferred;
1126         Key *key;
1127         AuthenticationConnection *ac;
1128         char *comment;
1129         int i, found;
1130
1131         TAILQ_INIT(&agent);     /* keys from the agent */
1132         TAILQ_INIT(&files);     /* keys from the config file */
1133         preferred = &authctxt->keys;
1134         TAILQ_INIT(preferred);  /* preferred order of keys */
1135
1136         /* list of keys stored in the filesystem */
1137         for (i = 0; i < options.num_identity_files; i++) {
1138                 key = options.identity_keys[i];
1139                 if (key && key->type == KEY_RSA1)
1140                         continue;
1141                 options.identity_keys[i] = NULL;
1142                 id = xmalloc(sizeof(*id));
1143                 memset(id, 0, sizeof(*id));
1144                 id->key = key;
1145                 id->filename = xstrdup(options.identity_files[i]);
1146                 TAILQ_INSERT_TAIL(&files, id, next);
1147         }
1148         /* list of keys supported by the agent */
1149         if ((ac = ssh_get_authentication_connection())) {
1150                 for (key = ssh_get_first_identity(ac, &comment, 2);
1151                     key != NULL;
1152                     key = ssh_get_next_identity(ac, &comment, 2)) {
1153                         found = 0;
1154                         TAILQ_FOREACH(id, &files, next) {
1155                                 /* agent keys from the config file are preferred */
1156                                 if (key_equal(key, id->key)) {
1157                                         key_free(key);
1158                                         xfree(comment);
1159                                         TAILQ_REMOVE(&files, id, next);
1160                                         TAILQ_INSERT_TAIL(preferred, id, next);
1161                                         id->ac = ac;
1162                                         found = 1;
1163                                         break;
1164                                 }
1165                         }
1166                         if (!found) {
1167                                 id = xmalloc(sizeof(*id));
1168                                 memset(id, 0, sizeof(*id));
1169                                 id->key = key;
1170                                 id->filename = comment;
1171                                 id->ac = ac;
1172                                 TAILQ_INSERT_TAIL(&agent, id, next);
1173                         }
1174                 }
1175                 /* append remaining agent keys */
1176                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1177                         TAILQ_REMOVE(&agent, id, next);
1178                         TAILQ_INSERT_TAIL(preferred, id, next);
1179                 }
1180                 authctxt->agent = ac;
1181         }
1182         /* append remaining keys from the config file */
1183         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1184                 TAILQ_REMOVE(&files, id, next);
1185                 TAILQ_INSERT_TAIL(preferred, id, next);
1186         }
1187         TAILQ_FOREACH(id, preferred, next) {
1188                 debug2("key: %s (%p)", id->filename, id->key);
1189         }
1190 }
1191
1192 static void
1193 pubkey_cleanup(Authctxt *authctxt)
1194 {
1195         Identity *id;
1196
1197         if (authctxt->agent != NULL)
1198                 ssh_close_authentication_connection(authctxt->agent);
1199         for (id = TAILQ_FIRST(&authctxt->keys); id;
1200             id = TAILQ_FIRST(&authctxt->keys)) {
1201                 TAILQ_REMOVE(&authctxt->keys, id, next);
1202                 if (id->key)
1203                         key_free(id->key);
1204                 if (id->filename)
1205                         xfree(id->filename);
1206                 xfree(id);
1207         }
1208 }
1209
1210 int
1211 userauth_pubkey(Authctxt *authctxt)
1212 {
1213         Identity *id;
1214         int sent = 0;
1215
1216         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1217                 if (id->tried++)
1218                         return (0);
1219                 /* move key to the end of the queue */
1220                 TAILQ_REMOVE(&authctxt->keys, id, next);
1221                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1222                 /*
1223                  * send a test message if we have the public key. for
1224                  * encrypted keys we cannot do this and have to load the
1225                  * private key instead
1226                  */
1227                 if (id->key && id->key->type != KEY_RSA1) {
1228                         debug("Offering public key: %s", id->filename);
1229                         sent = send_pubkey_test(authctxt, id);
1230                 } else if (id->key == NULL) {
1231                         debug("Trying private key: %s", id->filename);
1232                         id->key = load_identity_file(id->filename);
1233                         if (id->key != NULL) {
1234                                 id->isprivate = 1;
1235                                 sent = sign_and_send_pubkey(authctxt, id);
1236                                 key_free(id->key);
1237                                 id->key = NULL;
1238                         }
1239                 }
1240                 if (sent)
1241                         return (sent);
1242         }
1243         return (0);
1244 }
1245
1246 /*
1247  * Send userauth request message specifying keyboard-interactive method.
1248  */
1249 int
1250 userauth_kbdint(Authctxt *authctxt)
1251 {
1252         static int attempt = 0;
1253
1254         if (attempt++ >= options.number_of_password_prompts)
1255                 return 0;
1256         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1257         if (attempt > 1 && !authctxt->info_req_seen) {
1258                 debug3("userauth_kbdint: disable: no info_req_seen");
1259                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1260                 return 0;
1261         }
1262
1263         debug2("userauth_kbdint");
1264         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1265         packet_put_cstring(authctxt->server_user);
1266         packet_put_cstring(authctxt->service);
1267         packet_put_cstring(authctxt->method->name);
1268         packet_put_cstring("");                                 /* lang */
1269         packet_put_cstring(options.kbd_interactive_devices ?
1270             options.kbd_interactive_devices : "");
1271         packet_send();
1272
1273         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1274         return 1;
1275 }
1276
1277 /*
1278  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1279  */
1280 void
1281 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1282 {
1283         Authctxt *authctxt = ctxt;
1284         char *name, *inst, *lang, *prompt, *response;
1285         u_int num_prompts, i;
1286         int echo = 0;
1287
1288         debug2("input_userauth_info_req");
1289
1290         if (authctxt == NULL)
1291                 fatal("input_userauth_info_req: no authentication context");
1292
1293         authctxt->info_req_seen = 1;
1294
1295         name = packet_get_string(NULL);
1296         inst = packet_get_string(NULL);
1297         lang = packet_get_string(NULL);
1298         if (strlen(name) > 0)
1299                 logit("%s", name);
1300         if (strlen(inst) > 0)
1301                 logit("%s", inst);
1302         xfree(name);
1303         xfree(inst);
1304         xfree(lang);
1305
1306         num_prompts = packet_get_int();
1307         /*
1308          * Begin to build info response packet based on prompts requested.
1309          * We commit to providing the correct number of responses, so if
1310          * further on we run into a problem that prevents this, we have to
1311          * be sure and clean this up and send a correct error response.
1312          */
1313         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1314         packet_put_int(num_prompts);
1315
1316         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1317         for (i = 0; i < num_prompts; i++) {
1318                 prompt = packet_get_string(NULL);
1319                 echo = packet_get_char();
1320
1321                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1322
1323                 packet_put_cstring(response);
1324                 memset(response, 0, strlen(response));
1325                 xfree(response);
1326                 xfree(prompt);
1327         }
1328         packet_check_eom(); /* done with parsing incoming message. */
1329
1330         packet_add_padding(64);
1331         packet_send();
1332 }
1333
1334 static int
1335 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1336     u_char *data, u_int datalen)
1337 {
1338         Buffer b;
1339         struct stat st;
1340         pid_t pid;
1341         int to[2], from[2], status, version = 2;
1342
1343         debug2("ssh_keysign called");
1344
1345         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1346                 error("ssh_keysign: no installed: %s", strerror(errno));
1347                 return -1;
1348         }
1349         if (fflush(stdout) != 0)
1350                 error("ssh_keysign: fflush: %s", strerror(errno));
1351         if (pipe(to) < 0) {
1352                 error("ssh_keysign: pipe: %s", strerror(errno));
1353                 return -1;
1354         }
1355         if (pipe(from) < 0) {
1356                 error("ssh_keysign: pipe: %s", strerror(errno));
1357                 return -1;
1358         }
1359         if ((pid = fork()) < 0) {
1360                 error("ssh_keysign: fork: %s", strerror(errno));
1361                 return -1;
1362         }
1363         if (pid == 0) {
1364                 seteuid(getuid());
1365                 setuid(getuid());
1366                 close(from[0]);
1367                 if (dup2(from[1], STDOUT_FILENO) < 0)
1368                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1369                 close(to[1]);
1370                 if (dup2(to[0], STDIN_FILENO) < 0)
1371                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1372                 close(from[1]);
1373                 close(to[0]);
1374                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1375                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1376                     strerror(errno));
1377         }
1378         close(from[1]);
1379         close(to[0]);
1380
1381         buffer_init(&b);
1382         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1383         buffer_put_string(&b, data, datalen);
1384         if (ssh_msg_send(to[1], version, &b) == -1)
1385                 fatal("ssh_keysign: couldn't send request");
1386
1387         if (ssh_msg_recv(from[0], &b) < 0) {
1388                 error("ssh_keysign: no reply");
1389                 buffer_free(&b);
1390                 return -1;
1391         }
1392         close(from[0]);
1393         close(to[1]);
1394
1395         while (waitpid(pid, &status, 0) < 0)
1396                 if (errno != EINTR)
1397                         break;
1398
1399         if (buffer_get_char(&b) != version) {
1400                 error("ssh_keysign: bad version");
1401                 buffer_free(&b);
1402                 return -1;
1403         }
1404         *sigp = buffer_get_string(&b, lenp);
1405         buffer_free(&b);
1406
1407         return 0;
1408 }
1409
1410 int
1411 userauth_hostbased(Authctxt *authctxt)
1412 {
1413         Key *private = NULL;
1414         Sensitive *sensitive = authctxt->sensitive;
1415         Buffer b;
1416         u_char *signature, *blob;
1417         char *chost, *pkalg, *p;
1418         const char *service;
1419         u_int blen, slen;
1420         int ok, i, len, found = 0;
1421
1422         /* check for a useful key */
1423         for (i = 0; i < sensitive->nkeys; i++) {
1424                 private = sensitive->keys[i];
1425                 if (private && private->type != KEY_RSA1) {
1426                         found = 1;
1427                         /* we take and free the key */
1428                         sensitive->keys[i] = NULL;
1429                         break;
1430                 }
1431         }
1432         if (!found) {
1433                 debug("No more client hostkeys for hostbased authentication.");
1434                 return 0;
1435         }
1436         if (key_to_blob(private, &blob, &blen) == 0) {
1437                 key_free(private);
1438                 return 0;
1439         }
1440         /* figure out a name for the client host */
1441         p = get_local_name(packet_get_connection_in());
1442         if (p == NULL) {
1443                 error("userauth_hostbased: cannot get local ipaddr/name");
1444                 key_free(private);
1445                 return 0;
1446         }
1447         len = strlen(p) + 2;
1448         chost = xmalloc(len);
1449         strlcpy(chost, p, len);
1450         strlcat(chost, ".", len);
1451         debug2("userauth_hostbased: chost %s", chost);
1452         xfree(p);
1453
1454         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1455             authctxt->service;
1456         pkalg = xstrdup(key_ssh_name(private));
1457         buffer_init(&b);
1458         /* construct data */
1459         buffer_put_string(&b, session_id2, session_id2_len);
1460         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1461         buffer_put_cstring(&b, authctxt->server_user);
1462         buffer_put_cstring(&b, service);
1463         buffer_put_cstring(&b, authctxt->method->name);
1464         buffer_put_cstring(&b, pkalg);
1465         buffer_put_string(&b, blob, blen);
1466         buffer_put_cstring(&b, chost);
1467         buffer_put_cstring(&b, authctxt->local_user);
1468 #ifdef DEBUG_PK
1469         buffer_dump(&b);
1470 #endif
1471         if (sensitive->external_keysign)
1472                 ok = ssh_keysign(private, &signature, &slen,
1473                     buffer_ptr(&b), buffer_len(&b));
1474         else
1475                 ok = key_sign(private, &signature, &slen,
1476                     buffer_ptr(&b), buffer_len(&b));
1477         key_free(private);
1478         buffer_free(&b);
1479         if (ok != 0) {
1480                 error("key_sign failed");
1481                 xfree(chost);
1482                 xfree(pkalg);
1483                 return 0;
1484         }
1485         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1486         packet_put_cstring(authctxt->server_user);
1487         packet_put_cstring(authctxt->service);
1488         packet_put_cstring(authctxt->method->name);
1489         packet_put_cstring(pkalg);
1490         packet_put_string(blob, blen);
1491         packet_put_cstring(chost);
1492         packet_put_cstring(authctxt->local_user);
1493         packet_put_string(signature, slen);
1494         memset(signature, 's', slen);
1495         xfree(signature);
1496         xfree(chost);
1497         xfree(pkalg);
1498
1499         packet_send();
1500         return 1;
1501 }
1502
1503 /* find auth method */
1504
1505 /*
1506  * given auth method name, if configurable options permit this method fill
1507  * in auth_ident field and return true, otherwise return false.
1508  */
1509 static int
1510 authmethod_is_enabled(Authmethod *method)
1511 {
1512         if (method == NULL)
1513                 return 0;
1514         /* return false if options indicate this method is disabled */
1515         if  (method->enabled == NULL || *method->enabled == 0)
1516                 return 0;
1517         /* return false if batch mode is enabled but method needs interactive mode */
1518         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1519                 return 0;
1520         return 1;
1521 }
1522
1523 static Authmethod *
1524 authmethod_lookup(const char *name)
1525 {
1526         Authmethod *method = NULL;
1527         if (name != NULL)
1528                 for (method = authmethods; method->name != NULL; method++)
1529                         if (strcmp(name, method->name) == 0)
1530                                 return method;
1531         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1532         return NULL;
1533 }
1534
1535 /* XXX internal state */
1536 static Authmethod *current = NULL;
1537 static char *supported = NULL;
1538 static char *preferred = NULL;
1539
1540 /*
1541  * Given the authentication method list sent by the server, return the
1542  * next method we should try.  If the server initially sends a nil list,
1543  * use a built-in default list.
1544  */
1545 static Authmethod *
1546 authmethod_get(char *authlist)
1547 {
1548         char *name = NULL;
1549         u_int next;
1550
1551         /* Use a suitable default if we're passed a nil list.  */
1552         if (authlist == NULL || strlen(authlist) == 0)
1553                 authlist = options.preferred_authentications;
1554
1555         if (supported == NULL || strcmp(authlist, supported) != 0) {
1556                 debug3("start over, passed a different list %s", authlist);
1557                 if (supported != NULL)
1558                         xfree(supported);
1559                 supported = xstrdup(authlist);
1560                 preferred = options.preferred_authentications;
1561                 debug3("preferred %s", preferred);
1562                 current = NULL;
1563         } else if (current != NULL && authmethod_is_enabled(current))
1564                 return current;
1565
1566         for (;;) {
1567                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1568                         debug("No more authentication methods to try.");
1569                         current = NULL;
1570                         return NULL;
1571                 }
1572                 preferred += next;
1573                 debug3("authmethod_lookup %s", name);
1574                 debug3("remaining preferred: %s", preferred);
1575                 if ((current = authmethod_lookup(name)) != NULL &&
1576                     authmethod_is_enabled(current)) {
1577                         debug3("authmethod_is_enabled %s", name);
1578                         debug("Next authentication method: %s", name);
1579                         return current;
1580                 }
1581         }
1582 }
1583
1584 static char *
1585 authmethods_get(void)
1586 {
1587         Authmethod *method = NULL;
1588         Buffer b;
1589         char *list;
1590
1591         buffer_init(&b);
1592         for (method = authmethods; method->name != NULL; method++) {
1593                 if (authmethod_is_enabled(method)) {
1594                         if (buffer_len(&b) > 0)
1595                                 buffer_append(&b, ",", 1);
1596                         buffer_append(&b, method->name, strlen(method->name));
1597                 }
1598         }
1599         buffer_append(&b, "\0", 1);
1600         list = xstrdup(buffer_ptr(&b));
1601         buffer_free(&b);
1602         return list;
1603 }