crypto/openssh/sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.183 2010/04/26 22:28:24 djm Exp $ */
   2 /*
   3  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   4  * Copyright (c) 2008 Damien Miller.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include "includes.h"
  28
  29 #include <sys/types.h>
  30 #include <sys/socket.h>
  31 #include <sys/wait.h>
  32 #include <sys/stat.h>
  33
  34 #include <errno.h>
  35 #include <fcntl.h>
  36 #include <netdb.h>
  37 #include <pwd.h>
  38 #include <signal.h>
  39 #include <stdarg.h>
  40 #include <stdio.h>
  41 #include <string.h>
  42 #include <unistd.h>
  43 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H)
  44 #include <vis.h>
  45 #endif
  46
  47 #include "openbsd-compat/sys-queue.h"
  48
  49 #include "xmalloc.h"
  50 #include "ssh.h"
  51 #include "ssh2.h"
  52 #include "buffer.h"
  53 #include "packet.h"
  54 #include "compat.h"
  55 #include "cipher.h"
  56 #include "key.h"
  57 #include "kex.h"
  58 #include "myproposal.h"
  59 #include "sshconnect.h"
  60 #include "authfile.h"
  61 #include "dh.h"
  62 #include "authfd.h"
  63 #include "log.h"
  64 #include "readconf.h"
  65 #include "misc.h"
  66 #include "match.h"
  67 #include "dispatch.h"
  68 #include "canohost.h"
  69 #include "msg.h"
  70 #include "pathnames.h"
  71 #include "uidswap.h"
  72 #include "schnorr.h"
  73 #include "jpake.h"
  74
  75 #ifdef GSSAPI
  76 #include "ssh-gss.h"
  77 #endif
  78
  79 /* import */
  80 extern char *client_version_string;
  81 extern char *server_version_string;
  82 extern Options options;
  83 extern Kex *xxx_kex;
  84
  85 /* tty_flag is set in ssh.c. use this in ssh_userauth2 */
  86 /* if it is set then prevent the switch to the null cipher */
  87
  88 extern int tty_flag;
  89
  90 /*
  91  * SSH2 key exchange
  92  */
  93
  94 u_char *session_id2 = NULL;
  95 u_int session_id2_len = 0;
  96
  97 char *xxx_host;
  98 struct sockaddr *xxx_hostaddr;
  99
 100 Kex *xxx_kex = NULL;
 101
 102 static int
 103 verify_host_key_callback(Key *hostkey)
 104 {
 105         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
 106                 fatal("Host key verification failed.");
 107         return 0;
 108 }
 109
 110 void
 111 ssh_kex2(char *host, struct sockaddr *hostaddr)
 112 {
 113         Kex *kex;
 114
 115         xxx_host = host;
 116         xxx_hostaddr = hostaddr;
 117
 118         if (options.ciphers == (char *)-1) {
 119                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 120                 options.ciphers = NULL;
 121         }
 122         if (options.ciphers != NULL) {
 123                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 124                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 125         }
 126         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 127             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 128         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 129             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 130         if (options.compression) {
 131                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 132                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 133         } else {
 134                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 135                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 136         }
 137         if (options.macs != NULL) {
 138                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 139                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 140         }
 141         if (options.hostkeyalgorithms != NULL)
 142                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 143                     options.hostkeyalgorithms;
 144
 145         if (options.rekey_limit)
 146                 packet_set_rekey_limit((u_int32_t)options.rekey_limit);
 147
 148         /* start key exchange */
 149         kex = kex_setup(myproposal);
 150         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 151         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 152         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 153         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 154         kex->client_version_string=client_version_string;
 155         kex->server_version_string=server_version_string;
 156         kex->verify_host_key=&verify_host_key_callback;
 157
 158         xxx_kex = kex;
 159
 160         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 161
 162         if (options.use_roaming && !kex->roaming) {
 163                 debug("Roaming not allowed by server");
 164                 options.use_roaming = 0;
 165         }
 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         sig_atomic_t 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         void    (*cleanup)(Authctxt *authctxt);
 220         int     *enabled;       /* flag in option struct that enables method */
 221         int     *batch_flag;    /* flag in option struct that disables method */
 222 };
 223
 224 void    input_userauth_success(int, u_int32_t, void *);
 225 void    input_userauth_success_unexpected(int, u_int32_t, void *);
 226 void    input_userauth_failure(int, u_int32_t, void *);
 227 void    input_userauth_banner(int, u_int32_t, void *);
 228 void    input_userauth_error(int, u_int32_t, void *);
 229 void    input_userauth_info_req(int, u_int32_t, void *);
 230 void    input_userauth_pk_ok(int, u_int32_t, void *);
 231 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 232 void    input_userauth_jpake_server_step1(int, u_int32_t, void *);
 233 void    input_userauth_jpake_server_step2(int, u_int32_t, void *);
 234 void    input_userauth_jpake_server_confirm(int, u_int32_t, void *);
 235
 236 int     userauth_none(Authctxt *);
 237 int     userauth_pubkey(Authctxt *);
 238 int     userauth_passwd(Authctxt *);
 239 int     userauth_kbdint(Authctxt *);
 240 int     userauth_hostbased(Authctxt *);
 241 int     userauth_jpake(Authctxt *);
 242
 243 void    userauth_jpake_cleanup(Authctxt *);
 244
 245 #ifdef GSSAPI
 246 int     userauth_gssapi(Authctxt *authctxt);
 247 void    input_gssapi_response(int type, u_int32_t, void *);
 248 void    input_gssapi_token(int type, u_int32_t, void *);
 249 void    input_gssapi_hash(int type, u_int32_t, void *);
 250 void    input_gssapi_error(int, u_int32_t, void *);
 251 void    input_gssapi_errtok(int, u_int32_t, void *);
 252 #endif
 253
 254 void    userauth(Authctxt *, char *);
 255
 256 static int sign_and_send_pubkey(Authctxt *, Identity *);
 257 static void pubkey_prepare(Authctxt *);
 258 static void pubkey_cleanup(Authctxt *);
 259 static Key *load_identity_file(char *);
 260
 261 static Authmethod *authmethod_get(char *authlist);
 262 static Authmethod *authmethod_lookup(const char *name);
 263 static char *authmethods_get(void);
 264
 265 Authmethod authmethods[] = {
 266 #ifdef GSSAPI
 267         {"gssapi-with-mic",
 268                 userauth_gssapi,
 269                 NULL,
 270                 &options.gss_authentication,
 271                 NULL},
 272 #endif
 273         {"hostbased",
 274                 userauth_hostbased,
 275                 NULL,
 276                 &options.hostbased_authentication,
 277                 NULL},
 278         {"publickey",
 279                 userauth_pubkey,
 280                 NULL,
 281                 &options.pubkey_authentication,
 282                 NULL},
 283 #ifdef JPAKE
 284         {"jpake-01@openssh.com",
 285                 userauth_jpake,
 286                 userauth_jpake_cleanup,
 287                 &options.zero_knowledge_password_authentication,
 288                 &options.batch_mode},
 289 #endif
 290         {"keyboard-interactive",
 291                 userauth_kbdint,
 292                 NULL,
 293                 &options.kbd_interactive_authentication,
 294                 &options.batch_mode},
 295         {"password",
 296                 userauth_passwd,
 297                 NULL,
 298                 &options.password_authentication,
 299                 &options.batch_mode},
 300         {"none",
 301                 userauth_none,
 302                 NULL,
 303                 NULL,
 304                 NULL},
 305         {NULL, 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         /* if the user wants to use the none cipher do it */
 368         /* post authentication and only if the right conditions are met */
 369         /* both of the NONE commands must be true and there must be no */
 370         /* tty allocated */
 371         if ((options.none_switch == 1) && (options.none_enabled == 1))
 372         {
 373                 if (!tty_flag) /* no null on tty sessions */
 374                 {
 375                         debug("Requesting none rekeying...");
 376                         myproposal[PROPOSAL_ENC_ALGS_STOC] = "none";
 377                         myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none";
 378                         kex_prop2buf(&xxx_kex->my,myproposal);
 379                         packet_request_rekeying();
 380                         fprintf(stderr, "WARNING: ENABLED NONE CIPHER\n");
 381                 }
 382                 else
 383                 {
 384                         /* requested NONE cipher when in a tty */
 385                         debug("Cannot switch to NONE cipher with tty allocated");
 386                         fprintf(stderr, "NONE cipher switch disabled when a TTY is allocated\n");
 387                 }
 388         }
 389         debug("Authentication succeeded (%s).", authctxt.method->name);
 390 }
 391
 392 void
 393 userauth(Authctxt *authctxt, char *authlist)
 394 {
 395         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 396                 authctxt->method->cleanup(authctxt);
 397
 398         if (authctxt->methoddata) {
 399                 xfree(authctxt->methoddata);
 400                 authctxt->methoddata = NULL;
 401         }
 402         if (authlist == NULL) {
 403                 authlist = authctxt->authlist;
 404         } else {
 405                 if (authctxt->authlist)
 406                         xfree(authctxt->authlist);
 407                 authctxt->authlist = authlist;
 408         }
 409         for (;;) {
 410                 Authmethod *method = authmethod_get(authlist);
 411                 if (method == NULL)
 412                         fatal("Permission denied (%s).", authlist);
 413                 authctxt->method = method;
 414
 415                 /* reset the per method handler */
 416                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 417                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 418
 419                 /* and try new method */
 420                 if (method->userauth(authctxt) != 0) {
 421                         debug2("we sent a %s packet, wait for reply", method->name);
 422                         break;
 423                 } else {
 424                         debug2("we did not send a packet, disable method");
 425                         method->enabled = NULL;
 426                 }
 427         }
 428 }
 429
 430 /* ARGSUSED */
 431 void
 432 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 433 {
 434         fatal("input_userauth_error: bad message during authentication: "
 435             "type %d", type);
 436 }
 437
 438 /* ARGSUSED */
 439 void
 440 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 441 {
 442         char *msg, *raw, *lang;
 443         u_int len;
 444
 445         debug3("input_userauth_banner");
 446         raw = packet_get_string(&len);
 447         lang = packet_get_string(NULL);
 448         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
 449                 if (len > 65536)
 450                         len = 65536;
 451                 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
 452                 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH);
 453                 fprintf(stderr, "%s", msg);
 454                 xfree(msg);
 455         }
 456         xfree(raw);
 457         xfree(lang);
 458 }
 459
 460 /* ARGSUSED */
 461 void
 462 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 463 {
 464         Authctxt *authctxt = ctxt;
 465
 466         if (authctxt == NULL)
 467                 fatal("input_userauth_success: no authentication context");
 468         if (authctxt->authlist) {
 469                 xfree(authctxt->authlist);
 470                 authctxt->authlist = NULL;
 471         }
 472         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 473                 authctxt->method->cleanup(authctxt);
 474         if (authctxt->methoddata) {
 475                 xfree(authctxt->methoddata);
 476                 authctxt->methoddata = NULL;
 477         }
 478         authctxt->success = 1;                  /* break out */
 479 }
 480
 481 void
 482 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
 483 {
 484         Authctxt *authctxt = ctxt;
 485
 486         if (authctxt == NULL)
 487                 fatal("%s: no authentication context", __func__);
 488
 489         fatal("Unexpected authentication success during %s.",
 490             authctxt->method->name);
 491 }
 492
 493 /* ARGSUSED */
 494 void
 495 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 496 {
 497         Authctxt *authctxt = ctxt;
 498         char *authlist = NULL;
 499         int partial;
 500
 501         if (authctxt == NULL)
 502                 fatal("input_userauth_failure: no authentication context");
 503
 504         authlist = packet_get_string(NULL);
 505         partial = packet_get_char();
 506         packet_check_eom();
 507
 508         if (partial != 0)
 509                 logit("Authenticated with partial success.");
 510         debug("Authentications that can continue: %s", authlist);
 511
 512         userauth(authctxt, authlist);
 513 }
 514
 515 /* ARGSUSED */
 516 void
 517 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 518 {
 519         Authctxt *authctxt = ctxt;
 520         Key *key = NULL;
 521         Identity *id = NULL;
 522         Buffer b;
 523         int pktype, sent = 0;
 524         u_int alen, blen;
 525         char *pkalg, *fp;
 526         u_char *pkblob;
 527
 528         if (authctxt == NULL)
 529                 fatal("input_userauth_pk_ok: no authentication context");
 530         if (datafellows & SSH_BUG_PKOK) {
 531                 /* this is similar to SSH_BUG_PKAUTH */
 532                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 533                 pkblob = packet_get_string(&blen);
 534                 buffer_init(&b);
 535                 buffer_append(&b, pkblob, blen);
 536                 pkalg = buffer_get_string(&b, &alen);
 537                 buffer_free(&b);
 538         } else {
 539                 pkalg = packet_get_string(&alen);
 540                 pkblob = packet_get_string(&blen);
 541         }
 542         packet_check_eom();
 543
 544         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 545
 546         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 547                 debug("unknown pkalg %s", pkalg);
 548                 goto done;
 549         }
 550         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 551                 debug("no key from blob. pkalg %s", pkalg);
 552                 goto done;
 553         }
 554         if (key->type != pktype) {
 555                 error("input_userauth_pk_ok: type mismatch "
 556                     "for decoded key (received %d, expected %d)",
 557                     key->type, pktype);
 558                 goto done;
 559         }
 560         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 561         debug2("input_userauth_pk_ok: fp %s", fp);
 562         xfree(fp);
 563
 564         /*
 565          * search keys in the reverse order, because last candidate has been
 566          * moved to the end of the queue.  this also avoids confusion by
 567          * duplicate keys
 568          */
 569         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 570                 if (key_equal(key, id->key)) {
 571                         sent = sign_and_send_pubkey(authctxt, id);
 572                         break;
 573                 }
 574         }
 575 done:
 576         if (key != NULL)
 577                 key_free(key);
 578         xfree(pkalg);
 579         xfree(pkblob);
 580
 581         /* try another method if we did not send a packet */
 582         if (sent == 0)
 583                 userauth(authctxt, NULL);
 584 }
 585
 586 #ifdef GSSAPI
 587 int
 588 userauth_gssapi(Authctxt *authctxt)
 589 {
 590         Gssctxt *gssctxt = NULL;
 591         static gss_OID_set gss_supported = NULL;
 592         static u_int mech = 0;
 593         OM_uint32 min;
 594         int ok = 0;
 595
 596         /* Try one GSSAPI method at a time, rather than sending them all at
 597          * once. */
 598
 599         if (gss_supported == NULL)
 600                 gss_indicate_mechs(&min, &gss_supported);
 601
 602         /* Check to see if the mechanism is usable before we offer it */
 603         while (mech < gss_supported->count && !ok) {
 604                 /* My DER encoding requires length<128 */
 605                 if (gss_supported->elements[mech].length < 128 &&
 606                     ssh_gssapi_check_mechanism(&gssctxt,
 607                     &gss_supported->elements[mech], authctxt->host)) {
 608                         ok = 1; /* Mechanism works */
 609                 } else {
 610                         mech++;
 611                 }
 612         }
 613
 614         if (!ok)
 615                 return 0;
 616
 617         authctxt->methoddata=(void *)gssctxt;
 618
 619         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 620         packet_put_cstring(authctxt->server_user);
 621         packet_put_cstring(authctxt->service);
 622         packet_put_cstring(authctxt->method->name);
 623
 624         packet_put_int(1);
 625
 626         packet_put_int((gss_supported->elements[mech].length) + 2);
 627         packet_put_char(SSH_GSS_OIDTYPE);
 628         packet_put_char(gss_supported->elements[mech].length);
 629         packet_put_raw(gss_supported->elements[mech].elements,
 630             gss_supported->elements[mech].length);
 631
 632         packet_send();
 633
 634         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 635         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 636         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 637         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 638
 639         mech++; /* Move along to next candidate */
 640
 641         return 1;
 642 }
 643
 644 static OM_uint32
 645 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 646 {
 647         Authctxt *authctxt = ctxt;
 648         Gssctxt *gssctxt = authctxt->methoddata;
 649         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 650         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 651         gss_buffer_desc gssbuf;
 652         OM_uint32 status, ms, flags;
 653         Buffer b;
 654
 655         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 656             recv_tok, &send_tok, &flags);
 657
 658         if (send_tok.length > 0) {
 659                 if (GSS_ERROR(status))
 660                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 661                 else
 662                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 663
 664                 packet_put_string(send_tok.value, send_tok.length);
 665                 packet_send();
 666                 gss_release_buffer(&ms, &send_tok);
 667         }
 668
 669         if (status == GSS_S_COMPLETE) {
 670                 /* send either complete or MIC, depending on mechanism */
 671                 if (!(flags & GSS_C_INTEG_FLAG)) {
 672                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 673                         packet_send();
 674                 } else {
 675                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 676                             authctxt->service, "gssapi-with-mic");
 677
 678                         gssbuf.value = buffer_ptr(&b);
 679                         gssbuf.length = buffer_len(&b);
 680
 681                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 682
 683                         if (!GSS_ERROR(status)) {
 684                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 685                                 packet_put_string(mic.value, mic.length);
 686
 687                                 packet_send();
 688                         }
 689
 690                         buffer_free(&b);
 691                         gss_release_buffer(&ms, &mic);
 692                 }
 693         }
 694
 695         return status;
 696 }
 697
 698 /* ARGSUSED */
 699 void
 700 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 701 {
 702         Authctxt *authctxt = ctxt;
 703         Gssctxt *gssctxt;
 704         int oidlen;
 705         char *oidv;
 706
 707         if (authctxt == NULL)
 708                 fatal("input_gssapi_response: no authentication context");
 709         gssctxt = authctxt->methoddata;
 710
 711         /* Setup our OID */
 712         oidv = packet_get_string(&oidlen);
 713
 714         if (oidlen <= 2 ||
 715             oidv[0] != SSH_GSS_OIDTYPE ||
 716             oidv[1] != oidlen - 2) {
 717                 xfree(oidv);
 718                 debug("Badly encoded mechanism OID received");
 719                 userauth(authctxt, NULL);
 720                 return;
 721         }
 722
 723         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 724                 fatal("Server returned different OID than expected");
 725
 726         packet_check_eom();
 727
 728         xfree(oidv);
 729
 730         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 731                 /* Start again with next method on list */
 732                 debug("Trying to start again");
 733                 userauth(authctxt, NULL);
 734                 return;
 735         }
 736 }
 737
 738 /* ARGSUSED */
 739 void
 740 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 741 {
 742         Authctxt *authctxt = ctxt;
 743         gss_buffer_desc recv_tok;
 744         OM_uint32 status;
 745         u_int slen;
 746
 747         if (authctxt == NULL)
 748                 fatal("input_gssapi_response: no authentication context");
 749
 750         recv_tok.value = packet_get_string(&slen);
 751         recv_tok.length = slen; /* safe typecast */
 752
 753         packet_check_eom();
 754
 755         status = process_gssapi_token(ctxt, &recv_tok);
 756
 757         xfree(recv_tok.value);
 758
 759         if (GSS_ERROR(status)) {
 760                 /* Start again with the next method in the list */
 761                 userauth(authctxt, NULL);
 762                 return;
 763         }
 764 }
 765
 766 /* ARGSUSED */
 767 void
 768 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 769 {
 770         Authctxt *authctxt = ctxt;
 771         Gssctxt *gssctxt;
 772         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 773         gss_buffer_desc recv_tok;
 774         OM_uint32 status, ms;
 775         u_int len;
 776
 777         if (authctxt == NULL)
 778                 fatal("input_gssapi_response: no authentication context");
 779         gssctxt = authctxt->methoddata;
 780
 781         recv_tok.value = packet_get_string(&len);
 782         recv_tok.length = len;
 783
 784         packet_check_eom();
 785
 786         /* Stick it into GSSAPI and see what it says */
 787         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 788             &recv_tok, &send_tok, NULL);
 789
 790         xfree(recv_tok.value);
 791         gss_release_buffer(&ms, &send_tok);
 792
 793         /* Server will be returning a failed packet after this one */
 794 }
 795
 796 /* ARGSUSED */
 797 void
 798 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 799 {
 800         OM_uint32 maj, min;
 801         char *msg;
 802         char *lang;
 803
 804         maj=packet_get_int();
 805         min=packet_get_int();
 806         msg=packet_get_string(NULL);
 807         lang=packet_get_string(NULL);
 808
 809         packet_check_eom();
 810
 811         debug("Server GSSAPI Error:\n%s", msg);
 812         xfree(msg);
 813         xfree(lang);
 814 }
 815 #endif /* GSSAPI */
 816
 817 int
 818 userauth_none(Authctxt *authctxt)
 819 {
 820         /* initial userauth request */
 821         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 822         packet_put_cstring(authctxt->server_user);
 823         packet_put_cstring(authctxt->service);
 824         packet_put_cstring(authctxt->method->name);
 825         packet_send();
 826         return 1;
 827 }
 828
 829 int
 830 userauth_passwd(Authctxt *authctxt)
 831 {
 832         static int attempt = 0;
 833         char prompt[150];
 834         char *password;
 835         const char *host = options.host_key_alias ?  options.host_key_alias :
 836             authctxt->host;
 837
 838         if (attempt++ >= options.number_of_password_prompts)
 839                 return 0;
 840
 841         if (attempt != 1)
 842                 error("Permission denied, please try again.");
 843
 844         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 845             authctxt->server_user, host);
 846         password = read_passphrase(prompt, 0);
 847         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 848         packet_put_cstring(authctxt->server_user);
 849         packet_put_cstring(authctxt->service);
 850         packet_put_cstring(authctxt->method->name);
 851         packet_put_char(0);
 852         packet_put_cstring(password);
 853         memset(password, 0, strlen(password));
 854         xfree(password);
 855         packet_add_padding(64);
 856         packet_send();
 857
 858         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 859             &input_userauth_passwd_changereq);
 860
 861         return 1;
 862 }
 863
 864 /*
 865  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 866  */
 867 /* ARGSUSED */
 868 void
 869 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 870 {
 871         Authctxt *authctxt = ctxt;
 872         char *info, *lang, *password = NULL, *retype = NULL;
 873         char prompt[150];
 874         const char *host = options.host_key_alias ? options.host_key_alias :
 875             authctxt->host;
 876
 877         debug2("input_userauth_passwd_changereq");
 878
 879         if (authctxt == NULL)
 880                 fatal("input_userauth_passwd_changereq: "
 881                     "no authentication context");
 882
 883         info = packet_get_string(NULL);
 884         lang = packet_get_string(NULL);
 885         if (strlen(info) > 0)
 886                 logit("%s", info);
 887         xfree(info);
 888         xfree(lang);
 889         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 890         packet_put_cstring(authctxt->server_user);
 891         packet_put_cstring(authctxt->service);
 892         packet_put_cstring(authctxt->method->name);
 893         packet_put_char(1);                     /* additional info */
 894         snprintf(prompt, sizeof(prompt),
 895             "Enter %.30s@%.128s's old password: ",
 896             authctxt->server_user, host);
 897         password = read_passphrase(prompt, 0);
 898         packet_put_cstring(password);
 899         memset(password, 0, strlen(password));
 900         xfree(password);
 901         password = NULL;
 902         while (password == NULL) {
 903                 snprintf(prompt, sizeof(prompt),
 904                     "Enter %.30s@%.128s's new password: ",
 905                     authctxt->server_user, host);
 906                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 907                 if (password == NULL) {
 908                         /* bail out */
 909                         return;
 910                 }
 911                 snprintf(prompt, sizeof(prompt),
 912                     "Retype %.30s@%.128s's new password: ",
 913                     authctxt->server_user, host);
 914                 retype = read_passphrase(prompt, 0);
 915                 if (strcmp(password, retype) != 0) {
 916                         memset(password, 0, strlen(password));
 917                         xfree(password);
 918                         logit("Mismatch; try again, EOF to quit.");
 919                         password = NULL;
 920                 }
 921                 memset(retype, 0, strlen(retype));
 922                 xfree(retype);
 923         }
 924         packet_put_cstring(password);
 925         memset(password, 0, strlen(password));
 926         xfree(password);
 927         packet_add_padding(64);
 928         packet_send();
 929
 930         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 931             &input_userauth_passwd_changereq);
 932 }
 933
 934 #ifdef JPAKE
 935 static char *
 936 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt)
 937 {
 938         /* OpenBSD crypt(3) handles all of these */
 939         if (strcmp(crypt_scheme, "crypt") == 0 ||
 940             strcmp(crypt_scheme, "bcrypt") == 0 ||
 941             strcmp(crypt_scheme, "md5crypt") == 0 ||
 942             strcmp(crypt_scheme, "crypt-extended") == 0)
 943                 return xstrdup(crypt(password, salt));
 944         error("%s: unsupported password encryption scheme \"%.100s\"",
 945             __func__, crypt_scheme);
 946         return NULL;
 947 }
 948
 949 static BIGNUM *
 950 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme,
 951     const char *salt)
 952 {
 953         char prompt[256], *password, *crypted;
 954         u_char *secret;
 955         u_int secret_len;
 956         BIGNUM *ret;
 957
 958         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ",
 959             authctxt->server_user, authctxt->host);
 960         password = read_passphrase(prompt, 0);
 961
 962         if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) {
 963                 logit("Disabling %s authentication", authctxt->method->name);
 964                 authctxt->method->enabled = NULL;
 965                 /* Continue with an empty password to fail gracefully */
 966                 crypted = xstrdup("");
 967         }
 968
 969 #ifdef JPAKE_DEBUG
 970         debug3("%s: salt = %s", __func__, salt);
 971         debug3("%s: scheme = %s", __func__, crypt_scheme);
 972         debug3("%s: crypted = %s", __func__, crypted);
 973 #endif
 974
 975         if (hash_buffer(crypted, strlen(crypted), EVP_sha256(),
 976             &secret, &secret_len) != 0)
 977                 fatal("%s: hash_buffer", __func__);
 978
 979         bzero(password, strlen(password));
 980         bzero(crypted, strlen(crypted));
 981         xfree(password);
 982         xfree(crypted);
 983
 984         if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL)
 985                 fatal("%s: BN_bin2bn (secret)", __func__);
 986         bzero(secret, secret_len);
 987         xfree(secret);
 988
 989         return ret;
 990 }
 991
 992 /* ARGSUSED */
 993 void
 994 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt)
 995 {
 996         Authctxt *authctxt = ctxt;
 997         struct jpake_ctx *pctx = authctxt->methoddata;
 998         u_char *x3_proof, *x4_proof, *x2_s_proof;
 999         u_int x3_proof_len, x4_proof_len, x2_s_proof_len;
1000         char *crypt_scheme, *salt;
1001
1002         /* Disable this message */
1003         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL);
1004
1005         if ((pctx->g_x3 = BN_new()) == NULL ||
1006             (pctx->g_x4 = BN_new()) == NULL)
1007                 fatal("%s: BN_new", __func__);
1008
1009         /* Fetch step 1 values */
1010         crypt_scheme = packet_get_string(NULL);
1011         salt = packet_get_string(NULL);
1012         pctx->server_id = packet_get_string(&pctx->server_id_len);
1013         packet_get_bignum2(pctx->g_x3);
1014         packet_get_bignum2(pctx->g_x4);
1015         x3_proof = packet_get_string(&x3_proof_len);
1016         x4_proof = packet_get_string(&x4_proof_len);
1017         packet_check_eom();
1018
1019         JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__));
1020
1021         /* Obtain password and derive secret */
1022         pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt);
1023         bzero(crypt_scheme, strlen(crypt_scheme));
1024         bzero(salt, strlen(salt));
1025         xfree(crypt_scheme);
1026         xfree(salt);
1027         JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__));
1028
1029         /* Calculate step 2 values */
1030         jpake_step2(pctx->grp, pctx->s, pctx->g_x1,
1031             pctx->g_x3, pctx->g_x4, pctx->x2,
1032             pctx->server_id, pctx->server_id_len,
1033             pctx->client_id, pctx->client_id_len,
1034             x3_proof, x3_proof_len,
1035             x4_proof, x4_proof_len,
1036             &pctx->a,
1037             &x2_s_proof, &x2_s_proof_len);
1038
1039         bzero(x3_proof, x3_proof_len);
1040         bzero(x4_proof, x4_proof_len);
1041         xfree(x3_proof);
1042         xfree(x4_proof);
1043
1044         JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__));
1045
1046         /* Send values for step 2 */
1047         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2);
1048         packet_put_bignum2(pctx->a);
1049         packet_put_string(x2_s_proof, x2_s_proof_len);
1050         packet_send();
1051
1052         bzero(x2_s_proof, x2_s_proof_len);
1053         xfree(x2_s_proof);
1054
1055         /* Expect step 2 packet from peer */
1056         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2,
1057             input_userauth_jpake_server_step2);
1058 }
1059
1060 /* ARGSUSED */
1061 void
1062 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt)
1063 {
1064         Authctxt *authctxt = ctxt;
1065         struct jpake_ctx *pctx = authctxt->methoddata;
1066         u_char *x4_s_proof;
1067         u_int x4_s_proof_len;
1068
1069         /* Disable this message */
1070         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL);
1071
1072         if ((pctx->b = BN_new()) == NULL)
1073                 fatal("%s: BN_new", __func__);
1074
1075         /* Fetch step 2 values */
1076         packet_get_bignum2(pctx->b);
1077         x4_s_proof = packet_get_string(&x4_s_proof_len);
1078         packet_check_eom();
1079
1080         JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__));
1081
1082         /* Derive shared key and calculate confirmation hash */
1083         jpake_key_confirm(pctx->grp, pctx->s, pctx->b,
1084             pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4,
1085             pctx->client_id, pctx->client_id_len,
1086             pctx->server_id, pctx->server_id_len,
1087             session_id2, session_id2_len,
1088             x4_s_proof, x4_s_proof_len,
1089             &pctx->k,
1090             &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len);
1091
1092         bzero(x4_s_proof, x4_s_proof_len);
1093         xfree(x4_s_proof);
1094
1095         JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__));
1096
1097         /* Send key confirmation proof */
1098         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM);
1099         packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len);
1100         packet_send();
1101
1102         /* Expect confirmation from peer */
1103         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM,
1104             input_userauth_jpake_server_confirm);
1105 }
1106
1107 /* ARGSUSED */
1108 void
1109 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt)
1110 {
1111         Authctxt *authctxt = ctxt;
1112         struct jpake_ctx *pctx = authctxt->methoddata;
1113
1114         /* Disable this message */
1115         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL);
1116
1117         pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len);
1118         packet_check_eom();
1119
1120         JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__));
1121
1122         /* Verify expected confirmation hash */
1123         if (jpake_check_confirm(pctx->k,
1124             pctx->server_id, pctx->server_id_len,
1125             session_id2, session_id2_len,
1126             pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1)
1127                 debug("%s: %s success", __func__, authctxt->method->name);
1128         else {
1129                 debug("%s: confirmation mismatch", __func__);
1130                 /* XXX stash this so if auth succeeds then we can warn/kill */
1131         }
1132
1133         userauth_jpake_cleanup(authctxt);
1134 }
1135 #endif /* JPAKE */
1136
1137 static int
1138 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
1139     u_char *data, u_int datalen)
1140 {
1141         Key *prv;
1142         int ret;
1143
1144         /* the agent supports this key */
1145         if (id->ac)
1146                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1147                     data, datalen));
1148         /*
1149          * we have already loaded the private key or
1150          * the private key is stored in external hardware
1151          */
1152         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1153                 return (key_sign(id->key, sigp, lenp, data, datalen));
1154         /* load the private key from the file */
1155         if ((prv = load_identity_file(id->filename)) == NULL)
1156                 return (-1);
1157         ret = key_sign(prv, sigp, lenp, data, datalen);
1158         key_free(prv);
1159         return (ret);
1160 }
1161
1162 static int
1163 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1164 {
1165         Buffer b;
1166         u_char *blob, *signature;
1167         u_int bloblen, slen;
1168         u_int skip = 0;
1169         int ret = -1;
1170         int have_sig = 1;
1171         char *fp;
1172
1173         fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
1174         debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp);
1175         xfree(fp);
1176
1177         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1178                 /* we cannot handle this key */
1179                 debug3("sign_and_send_pubkey: cannot handle key");
1180                 return 0;
1181         }
1182         /* data to be signed */
1183         buffer_init(&b);
1184         if (datafellows & SSH_OLD_SESSIONID) {
1185                 buffer_append(&b, session_id2, session_id2_len);
1186                 skip = session_id2_len;
1187         } else {
1188                 buffer_put_string(&b, session_id2, session_id2_len);
1189                 skip = buffer_len(&b);
1190         }
1191         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1192         buffer_put_cstring(&b, authctxt->server_user);
1193         buffer_put_cstring(&b,
1194             datafellows & SSH_BUG_PKSERVICE ?
1195             "ssh-userauth" :
1196             authctxt->service);
1197         if (datafellows & SSH_BUG_PKAUTH) {
1198                 buffer_put_char(&b, have_sig);
1199         } else {
1200                 buffer_put_cstring(&b, authctxt->method->name);
1201                 buffer_put_char(&b, have_sig);
1202                 buffer_put_cstring(&b, key_ssh_name(id->key));
1203         }
1204         buffer_put_string(&b, blob, bloblen);
1205
1206         /* generate signature */
1207         ret = identity_sign(id, &signature, &slen,
1208             buffer_ptr(&b), buffer_len(&b));
1209         if (ret == -1) {
1210                 xfree(blob);
1211                 buffer_free(&b);
1212                 return 0;
1213         }
1214 #ifdef DEBUG_PK
1215         buffer_dump(&b);
1216 #endif
1217         if (datafellows & SSH_BUG_PKSERVICE) {
1218                 buffer_clear(&b);
1219                 buffer_append(&b, session_id2, session_id2_len);
1220                 skip = session_id2_len;
1221                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1222                 buffer_put_cstring(&b, authctxt->server_user);
1223                 buffer_put_cstring(&b, authctxt->service);
1224                 buffer_put_cstring(&b, authctxt->method->name);
1225                 buffer_put_char(&b, have_sig);
1226                 if (!(datafellows & SSH_BUG_PKAUTH))
1227                         buffer_put_cstring(&b, key_ssh_name(id->key));
1228                 buffer_put_string(&b, blob, bloblen);
1229         }
1230         xfree(blob);
1231
1232         /* append signature */
1233         buffer_put_string(&b, signature, slen);
1234         xfree(signature);
1235
1236         /* skip session id and packet type */
1237         if (buffer_len(&b) < skip + 1)
1238                 fatal("userauth_pubkey: internal error");
1239         buffer_consume(&b, skip + 1);
1240
1241         /* put remaining data from buffer into packet */
1242         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1243         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1244         buffer_free(&b);
1245         packet_send();
1246
1247         return 1;
1248 }
1249
1250 static int
1251 send_pubkey_test(Authctxt *authctxt, Identity *id)
1252 {
1253         u_char *blob;
1254         u_int bloblen, have_sig = 0;
1255
1256         debug3("send_pubkey_test");
1257
1258         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1259                 /* we cannot handle this key */
1260                 debug3("send_pubkey_test: cannot handle key");
1261                 return 0;
1262         }
1263         /* register callback for USERAUTH_PK_OK message */
1264         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1265
1266         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1267         packet_put_cstring(authctxt->server_user);
1268         packet_put_cstring(authctxt->service);
1269         packet_put_cstring(authctxt->method->name);
1270         packet_put_char(have_sig);
1271         if (!(datafellows & SSH_BUG_PKAUTH))
1272                 packet_put_cstring(key_ssh_name(id->key));
1273         packet_put_string(blob, bloblen);
1274         xfree(blob);
1275         packet_send();
1276         return 1;
1277 }
1278
1279 static Key *
1280 load_identity_file(char *filename)
1281 {
1282         Key *private;
1283         char prompt[300], *passphrase;
1284         int perm_ok = 0, quit, i;
1285         struct stat st;
1286
1287         if (stat(filename, &st) < 0) {
1288                 debug3("no such identity: %s", filename);
1289                 return NULL;
1290         }
1291         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1292         if (!perm_ok)
1293                 return NULL;
1294         if (private == NULL) {
1295                 if (options.batch_mode)
1296                         return NULL;
1297                 snprintf(prompt, sizeof prompt,
1298                     "Enter passphrase for key '%.100s': ", filename);
1299                 for (i = 0; i < options.number_of_password_prompts; i++) {
1300                         passphrase = read_passphrase(prompt, 0);
1301                         if (strcmp(passphrase, "") != 0) {
1302                                 private = key_load_private_type(KEY_UNSPEC,
1303                                     filename, passphrase, NULL, NULL);
1304                                 quit = 0;
1305                         } else {
1306                                 debug2("no passphrase given, try next key");
1307                                 quit = 1;
1308                         }
1309                         memset(passphrase, 0, strlen(passphrase));
1310                         xfree(passphrase);
1311                         if (private != NULL || quit)
1312                                 break;
1313                         debug2("bad passphrase given, try again...");
1314                 }
1315         }
1316         return private;
1317 }
1318
1319 /*
1320  * try keys in the following order:
1321  *      1. agent keys that are found in the config file
1322  *      2. other agent keys
1323  *      3. keys that are only listed in the config file
1324  */
1325 static void
1326 pubkey_prepare(Authctxt *authctxt)
1327 {
1328         Identity *id;
1329         Idlist agent, files, *preferred;
1330         Key *key;
1331         AuthenticationConnection *ac;
1332         char *comment;
1333         int i, found;
1334
1335         TAILQ_INIT(&agent);     /* keys from the agent */
1336         TAILQ_INIT(&files);     /* keys from the config file */
1337         preferred = &authctxt->keys;
1338         TAILQ_INIT(preferred);  /* preferred order of keys */
1339
1340         /* list of keys stored in the filesystem */
1341         for (i = 0; i < options.num_identity_files; i++) {
1342                 key = options.identity_keys[i];
1343                 if (key && key->type == KEY_RSA1)
1344                         continue;
1345                 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1346                         continue;
1347                 options.identity_keys[i] = NULL;
1348                 id = xcalloc(1, sizeof(*id));
1349                 id->key = key;
1350                 id->filename = xstrdup(options.identity_files[i]);
1351                 TAILQ_INSERT_TAIL(&files, id, next);
1352         }
1353         /* list of keys supported by the agent */
1354         if ((ac = ssh_get_authentication_connection())) {
1355                 for (key = ssh_get_first_identity(ac, &comment, 2);
1356                     key != NULL;
1357                     key = ssh_get_next_identity(ac, &comment, 2)) {
1358                         found = 0;
1359                         TAILQ_FOREACH(id, &files, next) {
1360                                 /* agent keys from the config file are preferred */
1361                                 if (key_equal(key, id->key)) {
1362                                         key_free(key);
1363                                         xfree(comment);
1364                                         TAILQ_REMOVE(&files, id, next);
1365                                         TAILQ_INSERT_TAIL(preferred, id, next);
1366                                         id->ac = ac;
1367                                         found = 1;
1368                                         break;
1369                                 }
1370                         }
1371                         if (!found && !options.identities_only) {
1372                                 id = xcalloc(1, sizeof(*id));
1373                                 id->key = key;
1374                                 id->filename = comment;
1375                                 id->ac = ac;
1376                                 TAILQ_INSERT_TAIL(&agent, id, next);
1377                         }
1378                 }
1379                 /* append remaining agent keys */
1380                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1381                         TAILQ_REMOVE(&agent, id, next);
1382                         TAILQ_INSERT_TAIL(preferred, id, next);
1383                 }
1384                 authctxt->agent = ac;
1385         }
1386         /* append remaining keys from the config file */
1387         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1388                 TAILQ_REMOVE(&files, id, next);
1389                 TAILQ_INSERT_TAIL(preferred, id, next);
1390         }
1391         TAILQ_FOREACH(id, preferred, next) {
1392                 debug2("key: %s (%p)", id->filename, id->key);
1393         }
1394 }
1395
1396 static void
1397 pubkey_cleanup(Authctxt *authctxt)
1398 {
1399         Identity *id;
1400
1401         if (authctxt->agent != NULL)
1402                 ssh_close_authentication_connection(authctxt->agent);
1403         for (id = TAILQ_FIRST(&authctxt->keys); id;
1404             id = TAILQ_FIRST(&authctxt->keys)) {
1405                 TAILQ_REMOVE(&authctxt->keys, id, next);
1406                 if (id->key)
1407                         key_free(id->key);
1408                 if (id->filename)
1409                         xfree(id->filename);
1410                 xfree(id);
1411         }
1412 }
1413
1414 int
1415 userauth_pubkey(Authctxt *authctxt)
1416 {
1417         Identity *id;
1418         int sent = 0;
1419
1420         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1421                 if (id->tried++)
1422                         return (0);
1423                 /* move key to the end of the queue */
1424                 TAILQ_REMOVE(&authctxt->keys, id, next);
1425                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1426                 /*
1427                  * send a test message if we have the public key. for
1428                  * encrypted keys we cannot do this and have to load the
1429                  * private key instead
1430                  */
1431                 if (id->key && id->key->type != KEY_RSA1) {
1432                         debug("Offering %s public key: %s", key_type(id->key),
1433                             id->filename);
1434                         sent = send_pubkey_test(authctxt, id);
1435                 } else if (id->key == NULL) {
1436                         debug("Trying private key: %s", id->filename);
1437                         id->key = load_identity_file(id->filename);
1438                         if (id->key != NULL) {
1439                                 id->isprivate = 1;
1440                                 sent = sign_and_send_pubkey(authctxt, id);
1441                                 key_free(id->key);
1442                                 id->key = NULL;
1443                         }
1444                 }
1445                 if (sent)
1446                         return (sent);
1447         }
1448         return (0);
1449 }
1450
1451 /*
1452  * Send userauth request message specifying keyboard-interactive method.
1453  */
1454 int
1455 userauth_kbdint(Authctxt *authctxt)
1456 {
1457         static int attempt = 0;
1458
1459         if (attempt++ >= options.number_of_password_prompts)
1460                 return 0;
1461         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1462         if (attempt > 1 && !authctxt->info_req_seen) {
1463                 debug3("userauth_kbdint: disable: no info_req_seen");
1464                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1465                 return 0;
1466         }
1467
1468         debug2("userauth_kbdint");
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("");                                 /* lang */
1474         packet_put_cstring(options.kbd_interactive_devices ?
1475             options.kbd_interactive_devices : "");
1476         packet_send();
1477
1478         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1479         return 1;
1480 }
1481
1482 /*
1483  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1484  */
1485 void
1486 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1487 {
1488         Authctxt *authctxt = ctxt;
1489         char *name, *inst, *lang, *prompt, *response;
1490         u_int num_prompts, i;
1491         int echo = 0;
1492
1493         debug2("input_userauth_info_req");
1494
1495         if (authctxt == NULL)
1496                 fatal("input_userauth_info_req: no authentication context");
1497
1498         authctxt->info_req_seen = 1;
1499
1500         name = packet_get_string(NULL);
1501         inst = packet_get_string(NULL);
1502         lang = packet_get_string(NULL);
1503         if (strlen(name) > 0)
1504                 logit("%s", name);
1505         if (strlen(inst) > 0)
1506                 logit("%s", inst);
1507         xfree(name);
1508         xfree(inst);
1509         xfree(lang);
1510
1511         num_prompts = packet_get_int();
1512         /*
1513          * Begin to build info response packet based on prompts requested.
1514          * We commit to providing the correct number of responses, so if
1515          * further on we run into a problem that prevents this, we have to
1516          * be sure and clean this up and send a correct error response.
1517          */
1518         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1519         packet_put_int(num_prompts);
1520
1521         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1522         for (i = 0; i < num_prompts; i++) {
1523                 prompt = packet_get_string(NULL);
1524                 echo = packet_get_char();
1525
1526                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1527
1528                 packet_put_cstring(response);
1529                 memset(response, 0, strlen(response));
1530                 xfree(response);
1531                 xfree(prompt);
1532         }
1533         packet_check_eom(); /* done with parsing incoming message. */
1534
1535         packet_add_padding(64);
1536         packet_send();
1537 }
1538
1539 static int
1540 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1541     u_char *data, u_int datalen)
1542 {
1543         Buffer b;
1544         struct stat st;
1545         pid_t pid;
1546         int to[2], from[2], status, version = 2;
1547
1548         debug2("ssh_keysign called");
1549
1550         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1551                 error("ssh_keysign: not installed: %s", strerror(errno));
1552                 return -1;
1553         }
1554         if (fflush(stdout) != 0)
1555                 error("ssh_keysign: fflush: %s", strerror(errno));
1556         if (pipe(to) < 0) {
1557                 error("ssh_keysign: pipe: %s", strerror(errno));
1558                 return -1;
1559         }
1560         if (pipe(from) < 0) {
1561                 error("ssh_keysign: pipe: %s", strerror(errno));
1562                 return -1;
1563         }
1564         if ((pid = fork()) < 0) {
1565                 error("ssh_keysign: fork: %s", strerror(errno));
1566                 return -1;
1567         }
1568         if (pid == 0) {
1569                 /* keep the socket on exec */
1570                 fcntl(packet_get_connection_in(), F_SETFD, 0);
1571                 permanently_drop_suid(getuid());
1572                 close(from[0]);
1573                 if (dup2(from[1], STDOUT_FILENO) < 0)
1574                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1575                 close(to[1]);
1576                 if (dup2(to[0], STDIN_FILENO) < 0)
1577                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1578                 close(from[1]);
1579                 close(to[0]);
1580                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1581                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1582                     strerror(errno));
1583         }
1584         close(from[1]);
1585         close(to[0]);
1586
1587         buffer_init(&b);
1588         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1589         buffer_put_string(&b, data, datalen);
1590         if (ssh_msg_send(to[1], version, &b) == -1)
1591                 fatal("ssh_keysign: couldn't send request");
1592
1593         if (ssh_msg_recv(from[0], &b) < 0) {
1594                 error("ssh_keysign: no reply");
1595                 buffer_free(&b);
1596                 return -1;
1597         }
1598         close(from[0]);
1599         close(to[1]);
1600
1601         while (waitpid(pid, &status, 0) < 0)
1602                 if (errno != EINTR)
1603                         break;
1604
1605         if (buffer_get_char(&b) != version) {
1606                 error("ssh_keysign: bad version");
1607                 buffer_free(&b);
1608                 return -1;
1609         }
1610         *sigp = buffer_get_string(&b, lenp);
1611         buffer_free(&b);
1612
1613         return 0;
1614 }
1615
1616 int
1617 userauth_hostbased(Authctxt *authctxt)
1618 {
1619         Key *private = NULL;
1620         Sensitive *sensitive = authctxt->sensitive;
1621         Buffer b;
1622         u_char *signature, *blob;
1623         char *chost, *pkalg, *p;
1624         const char *service;
1625         u_int blen, slen;
1626         int ok, i, found = 0;
1627
1628         /* check for a useful key */
1629         for (i = 0; i < sensitive->nkeys; i++) {
1630                 private = sensitive->keys[i];
1631                 if (private && private->type != KEY_RSA1) {
1632                         found = 1;
1633                         /* we take and free the key */
1634                         sensitive->keys[i] = NULL;
1635                         break;
1636                 }
1637         }
1638         if (!found) {
1639                 debug("No more client hostkeys for hostbased authentication.");
1640                 return 0;
1641         }
1642         if (key_to_blob(private, &blob, &blen) == 0) {
1643                 key_free(private);
1644                 return 0;
1645         }
1646         /* figure out a name for the client host */
1647         p = get_local_name(packet_get_connection_in());
1648         if (p == NULL) {
1649                 error("userauth_hostbased: cannot get local ipaddr/name");
1650                 key_free(private);
1651                 xfree(blob);
1652                 return 0;
1653         }
1654         xasprintf(&chost, "%s.", p);
1655         debug2("userauth_hostbased: chost %s", chost);
1656         xfree(p);
1657
1658         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1659             authctxt->service;
1660         pkalg = xstrdup(key_ssh_name(private));
1661         buffer_init(&b);
1662         /* construct data */
1663         buffer_put_string(&b, session_id2, session_id2_len);
1664         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1665         buffer_put_cstring(&b, authctxt->server_user);
1666         buffer_put_cstring(&b, service);
1667         buffer_put_cstring(&b, authctxt->method->name);
1668         buffer_put_cstring(&b, pkalg);
1669         buffer_put_string(&b, blob, blen);
1670         buffer_put_cstring(&b, chost);
1671         buffer_put_cstring(&b, authctxt->local_user);
1672 #ifdef DEBUG_PK
1673         buffer_dump(&b);
1674 #endif
1675         if (sensitive->external_keysign)
1676                 ok = ssh_keysign(private, &signature, &slen,
1677                     buffer_ptr(&b), buffer_len(&b));
1678         else
1679                 ok = key_sign(private, &signature, &slen,
1680                     buffer_ptr(&b), buffer_len(&b));
1681         key_free(private);
1682         buffer_free(&b);
1683         if (ok != 0) {
1684                 error("key_sign failed");
1685                 xfree(chost);
1686                 xfree(pkalg);
1687                 xfree(blob);
1688                 return 0;
1689         }
1690         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1691         packet_put_cstring(authctxt->server_user);
1692         packet_put_cstring(authctxt->service);
1693         packet_put_cstring(authctxt->method->name);
1694         packet_put_cstring(pkalg);
1695         packet_put_string(blob, blen);
1696         packet_put_cstring(chost);
1697         packet_put_cstring(authctxt->local_user);
1698         packet_put_string(signature, slen);
1699         memset(signature, 's', slen);
1700         xfree(signature);
1701         xfree(chost);
1702         xfree(pkalg);
1703         xfree(blob);
1704
1705         packet_send();
1706         return 1;
1707 }
1708
1709 #ifdef JPAKE
1710 int
1711 userauth_jpake(Authctxt *authctxt)
1712 {
1713         struct jpake_ctx *pctx;
1714         u_char *x1_proof, *x2_proof;
1715         u_int x1_proof_len, x2_proof_len;
1716         static int attempt = 0; /* XXX share with userauth_password's? */
1717
1718         if (attempt++ >= options.number_of_password_prompts)
1719                 return 0;
1720         if (attempt != 1)
1721                 error("Permission denied, please try again.");
1722
1723         if (authctxt->methoddata != NULL)
1724                 fatal("%s: authctxt->methoddata already set (%p)",
1725                     __func__, authctxt->methoddata);
1726
1727         authctxt->methoddata = pctx = jpake_new();
1728
1729         /*
1730          * Send request immediately, to get the protocol going while
1731          * we do the initial computations.
1732          */
1733         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1734         packet_put_cstring(authctxt->server_user);
1735         packet_put_cstring(authctxt->service);
1736         packet_put_cstring(authctxt->method->name);
1737         packet_send();
1738         packet_write_wait();
1739
1740         jpake_step1(pctx->grp,
1741             &pctx->client_id, &pctx->client_id_len,
1742             &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2,
1743             &x1_proof, &x1_proof_len,
1744             &x2_proof, &x2_proof_len);
1745
1746         JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__));
1747
1748         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1);
1749         packet_put_string(pctx->client_id, pctx->client_id_len);
1750         packet_put_bignum2(pctx->g_x1);
1751         packet_put_bignum2(pctx->g_x2);
1752         packet_put_string(x1_proof, x1_proof_len);
1753         packet_put_string(x2_proof, x2_proof_len);
1754         packet_send();
1755
1756         bzero(x1_proof, x1_proof_len);
1757         bzero(x2_proof, x2_proof_len);
1758         xfree(x1_proof);
1759         xfree(x2_proof);
1760
1761         /* Expect step 1 packet from peer */
1762         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1,
1763             input_userauth_jpake_server_step1);
1764         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS,
1765             &input_userauth_success_unexpected);
1766
1767         return 1;
1768 }
1769
1770 void
1771 userauth_jpake_cleanup(Authctxt *authctxt)
1772 {
1773         debug3("%s: clean up", __func__);
1774         if (authctxt->methoddata != NULL) {
1775                 jpake_free(authctxt->methoddata);
1776                 authctxt->methoddata = NULL;
1777         }
1778         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
1779 }
1780 #endif /* JPAKE */
1781
1782 /* find auth method */
1783
1784 /*
1785  * given auth method name, if configurable options permit this method fill
1786  * in auth_ident field and return true, otherwise return false.
1787  */
1788 static int
1789 authmethod_is_enabled(Authmethod *method)
1790 {
1791         if (method == NULL)
1792                 return 0;
1793         /* return false if options indicate this method is disabled */
1794         if  (method->enabled == NULL || *method->enabled == 0)
1795                 return 0;
1796         /* return false if batch mode is enabled but method needs interactive mode */
1797         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1798                 return 0;
1799         return 1;
1800 }
1801
1802 static Authmethod *
1803 authmethod_lookup(const char *name)
1804 {
1805         Authmethod *method = NULL;
1806         if (name != NULL)
1807                 for (method = authmethods; method->name != NULL; method++)
1808                         if (strcmp(name, method->name) == 0)
1809                                 return method;
1810         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1811         return NULL;
1812 }
1813
1814 /* XXX internal state */
1815 static Authmethod *current = NULL;
1816 static char *supported = NULL;
1817 static char *preferred = NULL;
1818
1819 /*
1820  * Given the authentication method list sent by the server, return the
1821  * next method we should try.  If the server initially sends a nil list,
1822  * use a built-in default list.
1823  */
1824 static Authmethod *
1825 authmethod_get(char *authlist)
1826 {
1827         char *name = NULL;
1828         u_int next;
1829
1830         /* Use a suitable default if we're passed a nil list.  */
1831         if (authlist == NULL || strlen(authlist) == 0)
1832                 authlist = options.preferred_authentications;
1833
1834         if (supported == NULL || strcmp(authlist, supported) != 0) {
1835                 debug3("start over, passed a different list %s", authlist);
1836                 if (supported != NULL)
1837                         xfree(supported);
1838                 supported = xstrdup(authlist);
1839                 preferred = options.preferred_authentications;
1840                 debug3("preferred %s", preferred);
1841                 current = NULL;
1842         } else if (current != NULL && authmethod_is_enabled(current))
1843                 return current;
1844
1845         for (;;) {
1846                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1847                         debug("No more authentication methods to try.");
1848                         current = NULL;
1849                         return NULL;
1850                 }
1851                 preferred += next;
1852                 debug3("authmethod_lookup %s", name);
1853                 debug3("remaining preferred: %s", preferred);
1854                 if ((current = authmethod_lookup(name)) != NULL &&
1855                     authmethod_is_enabled(current)) {
1856                         debug3("authmethod_is_enabled %s", name);
1857                         debug("Next authentication method: %s", name);
1858                         return current;
1859                 }
1860         }
1861 }
1862
1863 static char *
1864 authmethods_get(void)
1865 {
1866         Authmethod *method = NULL;
1867         Buffer b;
1868         char *list;
1869
1870         buffer_init(&b);
1871         for (method = authmethods; method->name != NULL; method++) {
1872                 if (authmethod_is_enabled(method)) {
1873                         if (buffer_len(&b) > 0)
1874                                 buffer_append(&b, ",", 1);
1875                         buffer_append(&b, method->name, strlen(method->name));
1876                 }
1877         }
1878         buffer_append(&b, "\0", 1);
1879         list = xstrdup(buffer_ptr(&b));
1880         buffer_free(&b);
1881         return list;
1882 }
1883