sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.172 2009/10/23 01:57:11 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 <netdb.h>
  36 #include <pwd.h>
  37 #include <signal.h>
  38 #include <stdarg.h>
  39 #include <stdio.h>
  40 #include <string.h>
  41 #include <unistd.h>
  42 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H)
  43 #include <vis.h>
  44 #endif
  45
  46 #include "openbsd-compat/sys-queue.h"
  47
  48 #include "xmalloc.h"
  49 #include "ssh.h"
  50 #include "ssh2.h"
  51 #include "buffer.h"
  52 #include "packet.h"
  53 #include "compat.h"
  54 #include "cipher.h"
  55 #include "key.h"
  56 #include "kex.h"
  57 #include "myproposal.h"
  58 #include "sshconnect.h"
  59 #include "authfile.h"
  60 #include "dh.h"
  61 #include "authfd.h"
  62 #include "log.h"
  63 #include "readconf.h"
  64 #include "misc.h"
  65 #include "match.h"
  66 #include "dispatch.h"
  67 #include "canohost.h"
  68 #include "msg.h"
  69 #include "pathnames.h"
  70 #include "uidswap.h"
  71 #include "schnorr.h"
  72 #include "jpake.h"
  73
  74 #ifdef GSSAPI
  75 #include "ssh-gss.h"
  76 #endif
  77
  78 /* import */
  79 extern char *client_version_string;
  80 extern char *server_version_string;
  81 extern Options options;
  82
  83 /*
  84  * SSH2 key exchange
  85  */
  86
  87 u_char *session_id2 = NULL;
  88 u_int session_id2_len = 0;
  89
  90 char *xxx_host;
  91 struct sockaddr *xxx_hostaddr;
  92
  93 Kex *xxx_kex = NULL;
  94
  95 static int
  96 verify_host_key_callback(Key *hostkey)
  97 {
  98         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
  99                 fatal("Host key verification failed.");
 100         return 0;
 101 }
 102
 103 void
 104 ssh_kex2(char *host, struct sockaddr *hostaddr)
 105 {
 106         Kex *kex;
 107
 108         xxx_host = host;
 109         xxx_hostaddr = hostaddr;
 110
 111         if (options.ciphers == (char *)-1) {
 112                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 113                 options.ciphers = NULL;
 114         }
 115         if (options.ciphers != NULL) {
 116                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 117                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 118         }
 119         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 120             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 121         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 122             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 123         if (options.compression) {
 124                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 125                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 126         } else {
 127                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 128                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 129         }
 130         if (options.macs != NULL) {
 131                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 132                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 133         }
 134         if (options.hostkeyalgorithms != NULL)
 135                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 136                     options.hostkeyalgorithms;
 137
 138         if (options.rekey_limit)
 139                 packet_set_rekey_limit((u_int32_t)options.rekey_limit);
 140
 141         /* start key exchange */
 142         kex = kex_setup(myproposal);
 143         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 144         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 145         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 146         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 147         kex->client_version_string=client_version_string;
 148         kex->server_version_string=server_version_string;
 149         kex->verify_host_key=&verify_host_key_callback;
 150
 151         xxx_kex = kex;
 152
 153         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 154
 155         session_id2 = kex->session_id;
 156         session_id2_len = kex->session_id_len;
 157
 158 #ifdef DEBUG_KEXDH
 159         /* send 1st encrypted/maced/compressed message */
 160         packet_start(SSH2_MSG_IGNORE);
 161         packet_put_cstring("markus");
 162         packet_send();
 163         packet_write_wait();
 164 #endif
 165 }
 166
 167 /*
 168  * Authenticate user
 169  */
 170
 171 typedef struct Authctxt Authctxt;
 172 typedef struct Authmethod Authmethod;
 173 typedef struct identity Identity;
 174 typedef struct idlist Idlist;
 175
 176 struct identity {
 177         TAILQ_ENTRY(identity) next;
 178         AuthenticationConnection *ac;   /* set if agent supports key */
 179         Key     *key;                   /* public/private key */
 180         char    *filename;              /* comment for agent-only keys */
 181         int     tried;
 182         int     isprivate;              /* key points to the private key */
 183 };
 184 TAILQ_HEAD(idlist, identity);
 185
 186 struct Authctxt {
 187         const char *server_user;
 188         const char *local_user;
 189         const char *host;
 190         const char *service;
 191         Authmethod *method;
 192         int success;
 193         char *authlist;
 194         /* pubkey */
 195         Idlist keys;
 196         AuthenticationConnection *agent;
 197         /* hostbased */
 198         Sensitive *sensitive;
 199         /* kbd-interactive */
 200         int info_req_seen;
 201         /* generic */
 202         void *methoddata;
 203 };
 204 struct Authmethod {
 205         char    *name;          /* string to compare against server's list */
 206         int     (*userauth)(Authctxt *authctxt);
 207         void    (*cleanup)(Authctxt *authctxt);
 208         int     *enabled;       /* flag in option struct that enables method */
 209         int     *batch_flag;    /* flag in option struct that disables method */
 210 };
 211
 212 void    input_userauth_success(int, u_int32_t, void *);
 213 void    input_userauth_success_unexpected(int, u_int32_t, void *);
 214 void    input_userauth_failure(int, u_int32_t, void *);
 215 void    input_userauth_banner(int, u_int32_t, void *);
 216 void    input_userauth_error(int, u_int32_t, void *);
 217 void    input_userauth_info_req(int, u_int32_t, void *);
 218 void    input_userauth_pk_ok(int, u_int32_t, void *);
 219 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 220 void    input_userauth_jpake_server_step1(int, u_int32_t, void *);
 221 void    input_userauth_jpake_server_step2(int, u_int32_t, void *);
 222 void    input_userauth_jpake_server_confirm(int, u_int32_t, void *);
 223
 224 int     userauth_none(Authctxt *);
 225 int     userauth_pubkey(Authctxt *);
 226 int     userauth_passwd(Authctxt *);
 227 int     userauth_kbdint(Authctxt *);
 228 int     userauth_hostbased(Authctxt *);
 229 int     userauth_jpake(Authctxt *);
 230
 231 void    userauth_jpake_cleanup(Authctxt *);
 232
 233 #ifdef GSSAPI
 234 int     userauth_gssapi(Authctxt *authctxt);
 235 void    input_gssapi_response(int type, u_int32_t, void *);
 236 void    input_gssapi_token(int type, u_int32_t, void *);
 237 void    input_gssapi_hash(int type, u_int32_t, void *);
 238 void    input_gssapi_error(int, u_int32_t, void *);
 239 void    input_gssapi_errtok(int, u_int32_t, void *);
 240 #endif
 241
 242 void    userauth(Authctxt *, char *);
 243
 244 static int sign_and_send_pubkey(Authctxt *, Identity *);
 245 static void pubkey_prepare(Authctxt *);
 246 static void pubkey_cleanup(Authctxt *);
 247 static Key *load_identity_file(char *);
 248
 249 static Authmethod *authmethod_get(char *authlist);
 250 static Authmethod *authmethod_lookup(const char *name);
 251 static char *authmethods_get(void);
 252
 253 Authmethod authmethods[] = {
 254 #ifdef GSSAPI
 255         {"gssapi-with-mic",
 256                 userauth_gssapi,
 257                 NULL,
 258                 &options.gss_authentication,
 259                 NULL},
 260 #endif
 261         {"hostbased",
 262                 userauth_hostbased,
 263                 NULL,
 264                 &options.hostbased_authentication,
 265                 NULL},
 266         {"publickey",
 267                 userauth_pubkey,
 268                 NULL,
 269                 &options.pubkey_authentication,
 270                 NULL},
 271 #ifdef JPAKE
 272         {"jpake-01@openssh.com",
 273                 userauth_jpake,
 274                 userauth_jpake_cleanup,
 275                 &options.zero_knowledge_password_authentication,
 276                 &options.batch_mode},
 277 #endif
 278         {"keyboard-interactive",
 279                 userauth_kbdint,
 280                 NULL,
 281                 &options.kbd_interactive_authentication,
 282                 &options.batch_mode},
 283         {"password",
 284                 userauth_passwd,
 285                 NULL,
 286                 &options.password_authentication,
 287                 &options.batch_mode},
 288         {"none",
 289                 userauth_none,
 290                 NULL,
 291                 NULL,
 292                 NULL},
 293         {NULL, NULL, NULL, NULL, NULL}
 294 };
 295
 296 void
 297 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 298     Sensitive *sensitive)
 299 {
 300         Authctxt authctxt;
 301         int type;
 302
 303         if (options.challenge_response_authentication)
 304                 options.kbd_interactive_authentication = 1;
 305
 306         packet_start(SSH2_MSG_SERVICE_REQUEST);
 307         packet_put_cstring("ssh-userauth");
 308         packet_send();
 309         debug("SSH2_MSG_SERVICE_REQUEST sent");
 310         packet_write_wait();
 311         type = packet_read();
 312         if (type != SSH2_MSG_SERVICE_ACCEPT)
 313                 fatal("Server denied authentication request: %d", type);
 314         if (packet_remaining() > 0) {
 315                 char *reply = packet_get_string(NULL);
 316                 debug2("service_accept: %s", reply);
 317                 xfree(reply);
 318         } else {
 319                 debug2("buggy server: service_accept w/o service");
 320         }
 321         packet_check_eom();
 322         debug("SSH2_MSG_SERVICE_ACCEPT received");
 323
 324         if (options.preferred_authentications == NULL)
 325                 options.preferred_authentications = authmethods_get();
 326
 327         /* setup authentication context */
 328         memset(&authctxt, 0, sizeof(authctxt));
 329         pubkey_prepare(&authctxt);
 330         authctxt.server_user = server_user;
 331         authctxt.local_user = local_user;
 332         authctxt.host = host;
 333         authctxt.service = "ssh-connection";            /* service name */
 334         authctxt.success = 0;
 335         authctxt.method = authmethod_lookup("none");
 336         authctxt.authlist = NULL;
 337         authctxt.methoddata = NULL;
 338         authctxt.sensitive = sensitive;
 339         authctxt.info_req_seen = 0;
 340         if (authctxt.method == NULL)
 341                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 342
 343         /* initial userauth request */
 344         userauth_none(&authctxt);
 345
 346         dispatch_init(&input_userauth_error);
 347         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 348         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 349         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 350         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 351
 352         pubkey_cleanup(&authctxt);
 353         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 354
 355         debug("Authentication succeeded (%s).", authctxt.method->name);
 356 }
 357
 358 void
 359 userauth(Authctxt *authctxt, char *authlist)
 360 {
 361         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 362                 authctxt->method->cleanup(authctxt);
 363
 364         if (authctxt->methoddata) {
 365                 xfree(authctxt->methoddata);
 366                 authctxt->methoddata = NULL;
 367         }
 368         if (authlist == NULL) {
 369                 authlist = authctxt->authlist;
 370         } else {
 371                 if (authctxt->authlist)
 372                         xfree(authctxt->authlist);
 373                 authctxt->authlist = authlist;
 374         }
 375         for (;;) {
 376                 Authmethod *method = authmethod_get(authlist);
 377                 if (method == NULL)
 378                         fatal("Permission denied (%s).", authlist);
 379                 authctxt->method = method;
 380
 381                 /* reset the per method handler */
 382                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 383                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 384
 385                 /* and try new method */
 386                 if (method->userauth(authctxt) != 0) {
 387                         debug2("we sent a %s packet, wait for reply", method->name);
 388                         break;
 389                 } else {
 390                         debug2("we did not send a packet, disable method");
 391                         method->enabled = NULL;
 392                 }
 393         }
 394 }
 395
 396 /* ARGSUSED */
 397 void
 398 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 399 {
 400         fatal("input_userauth_error: bad message during authentication: "
 401             "type %d", type);
 402 }
 403
 404 /* ARGSUSED */
 405 void
 406 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 407 {
 408         char *msg, *raw, *lang;
 409         u_int len;
 410
 411         debug3("input_userauth_banner");
 412         raw = packet_get_string(&len);
 413         lang = packet_get_string(NULL);
 414         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
 415                 if (len > 65536)
 416                         len = 65536;
 417                 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
 418                 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL);
 419                 fprintf(stderr, "%s", msg);
 420                 xfree(msg);
 421         }
 422         xfree(raw);
 423         xfree(lang);
 424 }
 425
 426 /* ARGSUSED */
 427 void
 428 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 429 {
 430         Authctxt *authctxt = ctxt;
 431
 432         if (authctxt == NULL)
 433                 fatal("input_userauth_success: no authentication context");
 434         if (authctxt->authlist) {
 435                 xfree(authctxt->authlist);
 436                 authctxt->authlist = NULL;
 437         }
 438         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 439                 authctxt->method->cleanup(authctxt);
 440         if (authctxt->methoddata) {
 441                 xfree(authctxt->methoddata);
 442                 authctxt->methoddata = NULL;
 443         }
 444         authctxt->success = 1;                  /* break out */
 445 }
 446
 447 void
 448 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
 449 {
 450         Authctxt *authctxt = ctxt;
 451
 452         if (authctxt == NULL)
 453                 fatal("%s: no authentication context", __func__);
 454
 455         fatal("Unexpected authentication success during %s.",
 456             authctxt->method->name);
 457 }
 458
 459 /* ARGSUSED */
 460 void
 461 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 462 {
 463         Authctxt *authctxt = ctxt;
 464         char *authlist = NULL;
 465         int partial;
 466
 467         if (authctxt == NULL)
 468                 fatal("input_userauth_failure: no authentication context");
 469
 470         authlist = packet_get_string(NULL);
 471         partial = packet_get_char();
 472         packet_check_eom();
 473
 474         if (partial != 0)
 475                 logit("Authenticated with partial success.");
 476         debug("Authentications that can continue: %s", authlist);
 477
 478         userauth(authctxt, authlist);
 479 }
 480
 481 /* ARGSUSED */
 482 void
 483 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 484 {
 485         Authctxt *authctxt = ctxt;
 486         Key *key = NULL;
 487         Identity *id = NULL;
 488         Buffer b;
 489         int pktype, sent = 0;
 490         u_int alen, blen;
 491         char *pkalg, *fp;
 492         u_char *pkblob;
 493
 494         if (authctxt == NULL)
 495                 fatal("input_userauth_pk_ok: no authentication context");
 496         if (datafellows & SSH_BUG_PKOK) {
 497                 /* this is similar to SSH_BUG_PKAUTH */
 498                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 499                 pkblob = packet_get_string(&blen);
 500                 buffer_init(&b);
 501                 buffer_append(&b, pkblob, blen);
 502                 pkalg = buffer_get_string(&b, &alen);
 503                 buffer_free(&b);
 504         } else {
 505                 pkalg = packet_get_string(&alen);
 506                 pkblob = packet_get_string(&blen);
 507         }
 508         packet_check_eom();
 509
 510         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 511
 512         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 513                 debug("unknown pkalg %s", pkalg);
 514                 goto done;
 515         }
 516         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 517                 debug("no key from blob. pkalg %s", pkalg);
 518                 goto done;
 519         }
 520         if (key->type != pktype) {
 521                 error("input_userauth_pk_ok: type mismatch "
 522                     "for decoded key (received %d, expected %d)",
 523                     key->type, pktype);
 524                 goto done;
 525         }
 526         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 527         debug2("input_userauth_pk_ok: fp %s", fp);
 528         xfree(fp);
 529
 530         /*
 531          * search keys in the reverse order, because last candidate has been
 532          * moved to the end of the queue.  this also avoids confusion by
 533          * duplicate keys
 534          */
 535         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 536                 if (key_equal(key, id->key)) {
 537                         sent = sign_and_send_pubkey(authctxt, id);
 538                         break;
 539                 }
 540         }
 541 done:
 542         if (key != NULL)
 543                 key_free(key);
 544         xfree(pkalg);
 545         xfree(pkblob);
 546
 547         /* try another method if we did not send a packet */
 548         if (sent == 0)
 549                 userauth(authctxt, NULL);
 550 }
 551
 552 #ifdef GSSAPI
 553 int
 554 userauth_gssapi(Authctxt *authctxt)
 555 {
 556         Gssctxt *gssctxt = NULL;
 557         static gss_OID_set gss_supported = NULL;
 558         static u_int mech = 0;
 559         OM_uint32 min;
 560         int ok = 0;
 561
 562         /* Try one GSSAPI method at a time, rather than sending them all at
 563          * once. */
 564
 565         if (gss_supported == NULL)
 566                 gss_indicate_mechs(&min, &gss_supported);
 567
 568         /* Check to see if the mechanism is usable before we offer it */
 569         while (mech < gss_supported->count && !ok) {
 570                 /* My DER encoding requires length<128 */
 571                 if (gss_supported->elements[mech].length < 128 &&
 572                     ssh_gssapi_check_mechanism(&gssctxt,
 573                     &gss_supported->elements[mech], authctxt->host)) {
 574                         ok = 1; /* Mechanism works */
 575                 } else {
 576                         mech++;
 577                 }
 578         }
 579
 580         if (!ok)
 581                 return 0;
 582
 583         authctxt->methoddata=(void *)gssctxt;
 584
 585         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 586         packet_put_cstring(authctxt->server_user);
 587         packet_put_cstring(authctxt->service);
 588         packet_put_cstring(authctxt->method->name);
 589
 590         packet_put_int(1);
 591
 592         packet_put_int((gss_supported->elements[mech].length) + 2);
 593         packet_put_char(SSH_GSS_OIDTYPE);
 594         packet_put_char(gss_supported->elements[mech].length);
 595         packet_put_raw(gss_supported->elements[mech].elements,
 596             gss_supported->elements[mech].length);
 597
 598         packet_send();
 599
 600         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 601         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 602         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 603         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 604
 605         mech++; /* Move along to next candidate */
 606
 607         return 1;
 608 }
 609
 610 static OM_uint32
 611 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 612 {
 613         Authctxt *authctxt = ctxt;
 614         Gssctxt *gssctxt = authctxt->methoddata;
 615         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 616         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 617         gss_buffer_desc gssbuf;
 618         OM_uint32 status, ms, flags;
 619         Buffer b;
 620
 621         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 622             recv_tok, &send_tok, &flags);
 623
 624         if (send_tok.length > 0) {
 625                 if (GSS_ERROR(status))
 626                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 627                 else
 628                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 629
 630                 packet_put_string(send_tok.value, send_tok.length);
 631                 packet_send();
 632                 gss_release_buffer(&ms, &send_tok);
 633         }
 634
 635         if (status == GSS_S_COMPLETE) {
 636                 /* send either complete or MIC, depending on mechanism */
 637                 if (!(flags & GSS_C_INTEG_FLAG)) {
 638                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 639                         packet_send();
 640                 } else {
 641                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 642                             authctxt->service, "gssapi-with-mic");
 643
 644                         gssbuf.value = buffer_ptr(&b);
 645                         gssbuf.length = buffer_len(&b);
 646
 647                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 648
 649                         if (!GSS_ERROR(status)) {
 650                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 651                                 packet_put_string(mic.value, mic.length);
 652
 653                                 packet_send();
 654                         }
 655
 656                         buffer_free(&b);
 657                         gss_release_buffer(&ms, &mic);
 658                 }
 659         }
 660
 661         return status;
 662 }
 663
 664 /* ARGSUSED */
 665 void
 666 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 667 {
 668         Authctxt *authctxt = ctxt;
 669         Gssctxt *gssctxt;
 670         int oidlen;
 671         char *oidv;
 672
 673         if (authctxt == NULL)
 674                 fatal("input_gssapi_response: no authentication context");
 675         gssctxt = authctxt->methoddata;
 676
 677         /* Setup our OID */
 678         oidv = packet_get_string(&oidlen);
 679
 680         if (oidlen <= 2 ||
 681             oidv[0] != SSH_GSS_OIDTYPE ||
 682             oidv[1] != oidlen - 2) {
 683                 xfree(oidv);
 684                 debug("Badly encoded mechanism OID received");
 685                 userauth(authctxt, NULL);
 686                 return;
 687         }
 688
 689         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 690                 fatal("Server returned different OID than expected");
 691
 692         packet_check_eom();
 693
 694         xfree(oidv);
 695
 696         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 697                 /* Start again with next method on list */
 698                 debug("Trying to start again");
 699                 userauth(authctxt, NULL);
 700                 return;
 701         }
 702 }
 703
 704 /* ARGSUSED */
 705 void
 706 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 707 {
 708         Authctxt *authctxt = ctxt;
 709         gss_buffer_desc recv_tok;
 710         OM_uint32 status;
 711         u_int slen;
 712
 713         if (authctxt == NULL)
 714                 fatal("input_gssapi_response: no authentication context");
 715
 716         recv_tok.value = packet_get_string(&slen);
 717         recv_tok.length = slen; /* safe typecast */
 718
 719         packet_check_eom();
 720
 721         status = process_gssapi_token(ctxt, &recv_tok);
 722
 723         xfree(recv_tok.value);
 724
 725         if (GSS_ERROR(status)) {
 726                 /* Start again with the next method in the list */
 727                 userauth(authctxt, NULL);
 728                 return;
 729         }
 730 }
 731
 732 /* ARGSUSED */
 733 void
 734 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 735 {
 736         Authctxt *authctxt = ctxt;
 737         Gssctxt *gssctxt;
 738         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 739         gss_buffer_desc recv_tok;
 740         OM_uint32 status, ms;
 741         u_int len;
 742
 743         if (authctxt == NULL)
 744                 fatal("input_gssapi_response: no authentication context");
 745         gssctxt = authctxt->methoddata;
 746
 747         recv_tok.value = packet_get_string(&len);
 748         recv_tok.length = len;
 749
 750         packet_check_eom();
 751
 752         /* Stick it into GSSAPI and see what it says */
 753         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 754             &recv_tok, &send_tok, NULL);
 755
 756         xfree(recv_tok.value);
 757         gss_release_buffer(&ms, &send_tok);
 758
 759         /* Server will be returning a failed packet after this one */
 760 }
 761
 762 /* ARGSUSED */
 763 void
 764 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 765 {
 766         OM_uint32 maj, min;
 767         char *msg;
 768         char *lang;
 769
 770         maj=packet_get_int();
 771         min=packet_get_int();
 772         msg=packet_get_string(NULL);
 773         lang=packet_get_string(NULL);
 774
 775         packet_check_eom();
 776
 777         debug("Server GSSAPI Error:\n%s", msg);
 778         xfree(msg);
 779         xfree(lang);
 780 }
 781 #endif /* GSSAPI */
 782
 783 int
 784 userauth_none(Authctxt *authctxt)
 785 {
 786         /* initial userauth request */
 787         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 788         packet_put_cstring(authctxt->server_user);
 789         packet_put_cstring(authctxt->service);
 790         packet_put_cstring(authctxt->method->name);
 791         packet_send();
 792         return 1;
 793 }
 794
 795 int
 796 userauth_passwd(Authctxt *authctxt)
 797 {
 798         static int attempt = 0;
 799         char prompt[150];
 800         char *password;
 801
 802         if (attempt++ >= options.number_of_password_prompts)
 803                 return 0;
 804
 805         if (attempt != 1)
 806                 error("Permission denied, please try again.");
 807
 808         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 809             authctxt->server_user, authctxt->host);
 810         password = read_passphrase(prompt, 0);
 811         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 812         packet_put_cstring(authctxt->server_user);
 813         packet_put_cstring(authctxt->service);
 814         packet_put_cstring(authctxt->method->name);
 815         packet_put_char(0);
 816         packet_put_cstring(password);
 817         memset(password, 0, strlen(password));
 818         xfree(password);
 819         packet_add_padding(64);
 820         packet_send();
 821
 822         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 823             &input_userauth_passwd_changereq);
 824
 825         return 1;
 826 }
 827
 828 /*
 829  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 830  */
 831 /* ARGSUSED */
 832 void
 833 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 834 {
 835         Authctxt *authctxt = ctxt;
 836         char *info, *lang, *password = NULL, *retype = NULL;
 837         char prompt[150];
 838
 839         debug2("input_userauth_passwd_changereq");
 840
 841         if (authctxt == NULL)
 842                 fatal("input_userauth_passwd_changereq: "
 843                     "no authentication context");
 844
 845         info = packet_get_string(NULL);
 846         lang = packet_get_string(NULL);
 847         if (strlen(info) > 0)
 848                 logit("%s", info);
 849         xfree(info);
 850         xfree(lang);
 851         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 852         packet_put_cstring(authctxt->server_user);
 853         packet_put_cstring(authctxt->service);
 854         packet_put_cstring(authctxt->method->name);
 855         packet_put_char(1);                     /* additional info */
 856         snprintf(prompt, sizeof(prompt),
 857             "Enter %.30s@%.128s's old password: ",
 858             authctxt->server_user, authctxt->host);
 859         password = read_passphrase(prompt, 0);
 860         packet_put_cstring(password);
 861         memset(password, 0, strlen(password));
 862         xfree(password);
 863         password = NULL;
 864         while (password == NULL) {
 865                 snprintf(prompt, sizeof(prompt),
 866                     "Enter %.30s@%.128s's new password: ",
 867                     authctxt->server_user, authctxt->host);
 868                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 869                 if (password == NULL) {
 870                         /* bail out */
 871                         return;
 872                 }
 873                 snprintf(prompt, sizeof(prompt),
 874                     "Retype %.30s@%.128s's new password: ",
 875                     authctxt->server_user, authctxt->host);
 876                 retype = read_passphrase(prompt, 0);
 877                 if (strcmp(password, retype) != 0) {
 878                         memset(password, 0, strlen(password));
 879                         xfree(password);
 880                         logit("Mismatch; try again, EOF to quit.");
 881                         password = NULL;
 882                 }
 883                 memset(retype, 0, strlen(retype));
 884                 xfree(retype);
 885         }
 886         packet_put_cstring(password);
 887         memset(password, 0, strlen(password));
 888         xfree(password);
 889         packet_add_padding(64);
 890         packet_send();
 891
 892         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 893             &input_userauth_passwd_changereq);
 894 }
 895
 896 #ifdef JPAKE
 897 static char *
 898 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt)
 899 {
 900         /* OpenBSD crypt(3) handles all of these */
 901         if (strcmp(crypt_scheme, "crypt") == 0 ||
 902             strcmp(crypt_scheme, "bcrypt") == 0 ||
 903             strcmp(crypt_scheme, "md5crypt") == 0 ||
 904             strcmp(crypt_scheme, "crypt-extended") == 0)
 905                 return xstrdup(crypt(password, salt));
 906         error("%s: unsupported password encryption scheme \"%.100s\"",
 907             __func__, crypt_scheme);
 908         return NULL;
 909 }
 910
 911 static BIGNUM *
 912 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme,
 913     const char *salt)
 914 {
 915         char prompt[256], *password, *crypted;
 916         u_char *secret;
 917         u_int secret_len;
 918         BIGNUM *ret;
 919
 920         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ",
 921             authctxt->server_user, authctxt->host);
 922         password = read_passphrase(prompt, 0);
 923
 924         if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) {
 925                 logit("Disabling %s authentication", authctxt->method->name);
 926                 authctxt->method->enabled = NULL;
 927                 /* Continue with an empty password to fail gracefully */
 928                 crypted = xstrdup("");
 929         }
 930
 931 #ifdef JPAKE_DEBUG
 932         debug3("%s: salt = %s", __func__, salt);
 933         debug3("%s: scheme = %s", __func__, crypt_scheme);
 934         debug3("%s: crypted = %s", __func__, crypted);
 935 #endif
 936
 937         if (hash_buffer(crypted, strlen(crypted), EVP_sha256(),
 938             &secret, &secret_len) != 0)
 939                 fatal("%s: hash_buffer", __func__);
 940
 941         bzero(password, strlen(password));
 942         bzero(crypted, strlen(crypted));
 943         xfree(password);
 944         xfree(crypted);
 945
 946         if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL)
 947                 fatal("%s: BN_bin2bn (secret)", __func__);
 948         bzero(secret, secret_len);
 949         xfree(secret);
 950
 951         return ret;
 952 }
 953
 954 /* ARGSUSED */
 955 void
 956 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt)
 957 {
 958         Authctxt *authctxt = ctxt;
 959         struct jpake_ctx *pctx = authctxt->methoddata;
 960         u_char *x3_proof, *x4_proof, *x2_s_proof;
 961         u_int x3_proof_len, x4_proof_len, x2_s_proof_len;
 962         char *crypt_scheme, *salt;
 963
 964         /* Disable this message */
 965         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL);
 966
 967         if ((pctx->g_x3 = BN_new()) == NULL ||
 968             (pctx->g_x4 = BN_new()) == NULL)
 969                 fatal("%s: BN_new", __func__);
 970
 971         /* Fetch step 1 values */
 972         crypt_scheme = packet_get_string(NULL);
 973         salt = packet_get_string(NULL);
 974         pctx->server_id = packet_get_string(&pctx->server_id_len);
 975         packet_get_bignum2(pctx->g_x3);
 976         packet_get_bignum2(pctx->g_x4);
 977         x3_proof = packet_get_string(&x3_proof_len);
 978         x4_proof = packet_get_string(&x4_proof_len);
 979         packet_check_eom();
 980
 981         JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__));
 982
 983         /* Obtain password and derive secret */
 984         pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt);
 985         bzero(crypt_scheme, strlen(crypt_scheme));
 986         bzero(salt, strlen(salt));
 987         xfree(crypt_scheme);
 988         xfree(salt);
 989         JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__));
 990
 991         /* Calculate step 2 values */
 992         jpake_step2(pctx->grp, pctx->s, pctx->g_x1,
 993             pctx->g_x3, pctx->g_x4, pctx->x2,
 994             pctx->server_id, pctx->server_id_len,
 995             pctx->client_id, pctx->client_id_len,
 996             x3_proof, x3_proof_len,
 997             x4_proof, x4_proof_len,
 998             &pctx->a,
 999             &x2_s_proof, &x2_s_proof_len);
1000
1001         bzero(x3_proof, x3_proof_len);
1002         bzero(x4_proof, x4_proof_len);
1003         xfree(x3_proof);
1004         xfree(x4_proof);
1005
1006         JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__));
1007
1008         /* Send values for step 2 */
1009         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2);
1010         packet_put_bignum2(pctx->a);
1011         packet_put_string(x2_s_proof, x2_s_proof_len);
1012         packet_send();
1013
1014         bzero(x2_s_proof, x2_s_proof_len);
1015         xfree(x2_s_proof);
1016
1017         /* Expect step 2 packet from peer */
1018         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2,
1019             input_userauth_jpake_server_step2);
1020 }
1021
1022 /* ARGSUSED */
1023 void
1024 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt)
1025 {
1026         Authctxt *authctxt = ctxt;
1027         struct jpake_ctx *pctx = authctxt->methoddata;
1028         u_char *x4_s_proof;
1029         u_int x4_s_proof_len;
1030
1031         /* Disable this message */
1032         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL);
1033
1034         if ((pctx->b = BN_new()) == NULL)
1035                 fatal("%s: BN_new", __func__);
1036
1037         /* Fetch step 2 values */
1038         packet_get_bignum2(pctx->b);
1039         x4_s_proof = packet_get_string(&x4_s_proof_len);
1040         packet_check_eom();
1041
1042         JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__));
1043
1044         /* Derive shared key and calculate confirmation hash */
1045         jpake_key_confirm(pctx->grp, pctx->s, pctx->b,
1046             pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4,
1047             pctx->client_id, pctx->client_id_len,
1048             pctx->server_id, pctx->server_id_len,
1049             session_id2, session_id2_len,
1050             x4_s_proof, x4_s_proof_len,
1051             &pctx->k,
1052             &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len);
1053
1054         bzero(x4_s_proof, x4_s_proof_len);
1055         xfree(x4_s_proof);
1056
1057         JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__));
1058
1059         /* Send key confirmation proof */
1060         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM);
1061         packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len);
1062         packet_send();
1063
1064         /* Expect confirmation from peer */
1065         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM,
1066             input_userauth_jpake_server_confirm);
1067 }
1068
1069 /* ARGSUSED */
1070 void
1071 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt)
1072 {
1073         Authctxt *authctxt = ctxt;
1074         struct jpake_ctx *pctx = authctxt->methoddata;
1075
1076         /* Disable this message */
1077         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL);
1078
1079         pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len);
1080         packet_check_eom();
1081
1082         JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__));
1083
1084         /* Verify expected confirmation hash */
1085         if (jpake_check_confirm(pctx->k,
1086             pctx->server_id, pctx->server_id_len,
1087             session_id2, session_id2_len,
1088             pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1)
1089                 debug("%s: %s success", __func__, authctxt->method->name);
1090         else {
1091                 debug("%s: confirmation mismatch", __func__);
1092                 /* XXX stash this so if auth succeeds then we can warn/kill */
1093         }
1094
1095         userauth_jpake_cleanup(authctxt);
1096 }
1097 #endif /* JPAKE */
1098
1099 static int
1100 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
1101     u_char *data, u_int datalen)
1102 {
1103         Key *prv;
1104         int ret;
1105
1106         /* the agent supports this key */
1107         if (id->ac)
1108                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1109                     data, datalen));
1110         /*
1111          * we have already loaded the private key or
1112          * the private key is stored in external hardware
1113          */
1114         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1115                 return (key_sign(id->key, sigp, lenp, data, datalen));
1116         /* load the private key from the file */
1117         if ((prv = load_identity_file(id->filename)) == NULL)
1118                 return (-1);
1119         ret = key_sign(prv, sigp, lenp, data, datalen);
1120         key_free(prv);
1121         return (ret);
1122 }
1123
1124 static int
1125 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1126 {
1127         Buffer b;
1128         u_char *blob, *signature;
1129         u_int bloblen, slen;
1130         u_int skip = 0;
1131         int ret = -1;
1132         int have_sig = 1;
1133
1134         debug3("sign_and_send_pubkey");
1135
1136         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1137                 /* we cannot handle this key */
1138                 debug3("sign_and_send_pubkey: cannot handle key");
1139                 return 0;
1140         }
1141         /* data to be signed */
1142         buffer_init(&b);
1143         if (datafellows & SSH_OLD_SESSIONID) {
1144                 buffer_append(&b, session_id2, session_id2_len);
1145                 skip = session_id2_len;
1146         } else {
1147                 buffer_put_string(&b, session_id2, session_id2_len);
1148                 skip = buffer_len(&b);
1149         }
1150         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1151         buffer_put_cstring(&b, authctxt->server_user);
1152         buffer_put_cstring(&b,
1153             datafellows & SSH_BUG_PKSERVICE ?
1154             "ssh-userauth" :
1155             authctxt->service);
1156         if (datafellows & SSH_BUG_PKAUTH) {
1157                 buffer_put_char(&b, have_sig);
1158         } else {
1159                 buffer_put_cstring(&b, authctxt->method->name);
1160                 buffer_put_char(&b, have_sig);
1161                 buffer_put_cstring(&b, key_ssh_name(id->key));
1162         }
1163         buffer_put_string(&b, blob, bloblen);
1164
1165         /* generate signature */
1166         ret = identity_sign(id, &signature, &slen,
1167             buffer_ptr(&b), buffer_len(&b));
1168         if (ret == -1) {
1169                 xfree(blob);
1170                 buffer_free(&b);
1171                 return 0;
1172         }
1173 #ifdef DEBUG_PK
1174         buffer_dump(&b);
1175 #endif
1176         if (datafellows & SSH_BUG_PKSERVICE) {
1177                 buffer_clear(&b);
1178                 buffer_append(&b, session_id2, session_id2_len);
1179                 skip = session_id2_len;
1180                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1181                 buffer_put_cstring(&b, authctxt->server_user);
1182                 buffer_put_cstring(&b, authctxt->service);
1183                 buffer_put_cstring(&b, authctxt->method->name);
1184                 buffer_put_char(&b, have_sig);
1185                 if (!(datafellows & SSH_BUG_PKAUTH))
1186                         buffer_put_cstring(&b, key_ssh_name(id->key));
1187                 buffer_put_string(&b, blob, bloblen);
1188         }
1189         xfree(blob);
1190
1191         /* append signature */
1192         buffer_put_string(&b, signature, slen);
1193         xfree(signature);
1194
1195         /* skip session id and packet type */
1196         if (buffer_len(&b) < skip + 1)
1197                 fatal("userauth_pubkey: internal error");
1198         buffer_consume(&b, skip + 1);
1199
1200         /* put remaining data from buffer into packet */
1201         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1202         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1203         buffer_free(&b);
1204         packet_send();
1205
1206         return 1;
1207 }
1208
1209 static int
1210 send_pubkey_test(Authctxt *authctxt, Identity *id)
1211 {
1212         u_char *blob;
1213         u_int bloblen, have_sig = 0;
1214
1215         debug3("send_pubkey_test");
1216
1217         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1218                 /* we cannot handle this key */
1219                 debug3("send_pubkey_test: cannot handle key");
1220                 return 0;
1221         }
1222         /* register callback for USERAUTH_PK_OK message */
1223         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1224
1225         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1226         packet_put_cstring(authctxt->server_user);
1227         packet_put_cstring(authctxt->service);
1228         packet_put_cstring(authctxt->method->name);
1229         packet_put_char(have_sig);
1230         if (!(datafellows & SSH_BUG_PKAUTH))
1231                 packet_put_cstring(key_ssh_name(id->key));
1232         packet_put_string(blob, bloblen);
1233         xfree(blob);
1234         packet_send();
1235         return 1;
1236 }
1237
1238 static Key *
1239 load_identity_file(char *filename)
1240 {
1241         Key *private;
1242         char prompt[300], *passphrase;
1243         int perm_ok, quit, i;
1244         struct stat st;
1245
1246         if (stat(filename, &st) < 0) {
1247                 debug3("no such identity: %s", filename);
1248                 return NULL;
1249         }
1250         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1251         if (!perm_ok)
1252                 return NULL;
1253         if (private == NULL) {
1254                 if (options.batch_mode)
1255                         return NULL;
1256                 snprintf(prompt, sizeof prompt,
1257                     "Enter passphrase for key '%.100s': ", filename);
1258                 for (i = 0; i < options.number_of_password_prompts; i++) {
1259                         passphrase = read_passphrase(prompt, 0);
1260                         if (strcmp(passphrase, "") != 0) {
1261                                 private = key_load_private_type(KEY_UNSPEC,
1262                                     filename, passphrase, NULL, NULL);
1263                                 quit = 0;
1264                         } else {
1265                                 debug2("no passphrase given, try next key");
1266                                 quit = 1;
1267                         }
1268                         memset(passphrase, 0, strlen(passphrase));
1269                         xfree(passphrase);
1270                         if (private != NULL || quit)
1271                                 break;
1272                         debug2("bad passphrase given, try again...");
1273                 }
1274         }
1275         return private;
1276 }
1277
1278 /*
1279  * try keys in the following order:
1280  *      1. agent keys that are found in the config file
1281  *      2. other agent keys
1282  *      3. keys that are only listed in the config file
1283  */
1284 static void
1285 pubkey_prepare(Authctxt *authctxt)
1286 {
1287         Identity *id;
1288         Idlist agent, files, *preferred;
1289         Key *key;
1290         AuthenticationConnection *ac;
1291         char *comment;
1292         int i, found;
1293
1294         TAILQ_INIT(&agent);     /* keys from the agent */
1295         TAILQ_INIT(&files);     /* keys from the config file */
1296         preferred = &authctxt->keys;
1297         TAILQ_INIT(preferred);  /* preferred order of keys */
1298
1299         /* list of keys stored in the filesystem */
1300         for (i = 0; i < options.num_identity_files; i++) {
1301                 key = options.identity_keys[i];
1302                 if (key && key->type == KEY_RSA1)
1303                         continue;
1304                 options.identity_keys[i] = NULL;
1305                 id = xcalloc(1, sizeof(*id));
1306                 id->key = key;
1307                 id->filename = xstrdup(options.identity_files[i]);
1308                 TAILQ_INSERT_TAIL(&files, id, next);
1309         }
1310         /* list of keys supported by the agent */
1311         if ((ac = ssh_get_authentication_connection())) {
1312                 for (key = ssh_get_first_identity(ac, &comment, 2);
1313                     key != NULL;
1314                     key = ssh_get_next_identity(ac, &comment, 2)) {
1315                         found = 0;
1316                         TAILQ_FOREACH(id, &files, next) {
1317                                 /* agent keys from the config file are preferred */
1318                                 if (key_equal(key, id->key)) {
1319                                         key_free(key);
1320                                         xfree(comment);
1321                                         TAILQ_REMOVE(&files, id, next);
1322                                         TAILQ_INSERT_TAIL(preferred, id, next);
1323                                         id->ac = ac;
1324                                         found = 1;
1325                                         break;
1326                                 }
1327                         }
1328                         if (!found && !options.identities_only) {
1329                                 id = xcalloc(1, sizeof(*id));
1330                                 id->key = key;
1331                                 id->filename = comment;
1332                                 id->ac = ac;
1333                                 TAILQ_INSERT_TAIL(&agent, id, next);
1334                         }
1335                 }
1336                 /* append remaining agent keys */
1337                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1338                         TAILQ_REMOVE(&agent, id, next);
1339                         TAILQ_INSERT_TAIL(preferred, id, next);
1340                 }
1341                 authctxt->agent = ac;
1342         }
1343         /* append remaining keys from the config file */
1344         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1345                 TAILQ_REMOVE(&files, id, next);
1346                 TAILQ_INSERT_TAIL(preferred, id, next);
1347         }
1348         TAILQ_FOREACH(id, preferred, next) {
1349                 debug2("key: %s (%p)", id->filename, id->key);
1350         }
1351 }
1352
1353 static void
1354 pubkey_cleanup(Authctxt *authctxt)
1355 {
1356         Identity *id;
1357
1358         if (authctxt->agent != NULL)
1359                 ssh_close_authentication_connection(authctxt->agent);
1360         for (id = TAILQ_FIRST(&authctxt->keys); id;
1361             id = TAILQ_FIRST(&authctxt->keys)) {
1362                 TAILQ_REMOVE(&authctxt->keys, id, next);
1363                 if (id->key)
1364                         key_free(id->key);
1365                 if (id->filename)
1366                         xfree(id->filename);
1367                 xfree(id);
1368         }
1369 }
1370
1371 int
1372 userauth_pubkey(Authctxt *authctxt)
1373 {
1374         Identity *id;
1375         int sent = 0;
1376
1377         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1378                 if (id->tried++)
1379                         return (0);
1380                 /* move key to the end of the queue */
1381                 TAILQ_REMOVE(&authctxt->keys, id, next);
1382                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1383                 /*
1384                  * send a test message if we have the public key. for
1385                  * encrypted keys we cannot do this and have to load the
1386                  * private key instead
1387                  */
1388                 if (id->key && id->key->type != KEY_RSA1) {
1389                         debug("Offering public key: %s", id->filename);
1390                         sent = send_pubkey_test(authctxt, id);
1391                 } else if (id->key == NULL) {
1392                         debug("Trying private key: %s", id->filename);
1393                         id->key = load_identity_file(id->filename);
1394                         if (id->key != NULL) {
1395                                 id->isprivate = 1;
1396                                 sent = sign_and_send_pubkey(authctxt, id);
1397                                 key_free(id->key);
1398                                 id->key = NULL;
1399                         }
1400                 }
1401                 if (sent)
1402                         return (sent);
1403         }
1404         return (0);
1405 }
1406
1407 /*
1408  * Send userauth request message specifying keyboard-interactive method.
1409  */
1410 int
1411 userauth_kbdint(Authctxt *authctxt)
1412 {
1413         static int attempt = 0;
1414
1415         if (attempt++ >= options.number_of_password_prompts)
1416                 return 0;
1417         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1418         if (attempt > 1 && !authctxt->info_req_seen) {
1419                 debug3("userauth_kbdint: disable: no info_req_seen");
1420                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1421                 return 0;
1422         }
1423
1424         debug2("userauth_kbdint");
1425         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1426         packet_put_cstring(authctxt->server_user);
1427         packet_put_cstring(authctxt->service);
1428         packet_put_cstring(authctxt->method->name);
1429         packet_put_cstring("");                                 /* lang */
1430         packet_put_cstring(options.kbd_interactive_devices ?
1431             options.kbd_interactive_devices : "");
1432         packet_send();
1433
1434         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1435         return 1;
1436 }
1437
1438 /*
1439  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1440  */
1441 void
1442 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1443 {
1444         Authctxt *authctxt = ctxt;
1445         char *name, *inst, *lang, *prompt, *response;
1446         u_int num_prompts, i;
1447         int echo = 0;
1448
1449         debug2("input_userauth_info_req");
1450
1451         if (authctxt == NULL)
1452                 fatal("input_userauth_info_req: no authentication context");
1453
1454         authctxt->info_req_seen = 1;
1455
1456         name = packet_get_string(NULL);
1457         inst = packet_get_string(NULL);
1458         lang = packet_get_string(NULL);
1459         if (strlen(name) > 0)
1460                 logit("%s", name);
1461         if (strlen(inst) > 0)
1462                 logit("%s", inst);
1463         xfree(name);
1464         xfree(inst);
1465         xfree(lang);
1466
1467         num_prompts = packet_get_int();
1468         /*
1469          * Begin to build info response packet based on prompts requested.
1470          * We commit to providing the correct number of responses, so if
1471          * further on we run into a problem that prevents this, we have to
1472          * be sure and clean this up and send a correct error response.
1473          */
1474         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1475         packet_put_int(num_prompts);
1476
1477         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1478         for (i = 0; i < num_prompts; i++) {
1479                 prompt = packet_get_string(NULL);
1480                 echo = packet_get_char();
1481
1482                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1483
1484                 packet_put_cstring(response);
1485                 memset(response, 0, strlen(response));
1486                 xfree(response);
1487                 xfree(prompt);
1488         }
1489         packet_check_eom(); /* done with parsing incoming message. */
1490
1491         packet_add_padding(64);
1492         packet_send();
1493 }
1494
1495 static int
1496 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1497     u_char *data, u_int datalen)
1498 {
1499         Buffer b;
1500         struct stat st;
1501         pid_t pid;
1502         int to[2], from[2], status, version = 2;
1503
1504         debug2("ssh_keysign called");
1505
1506         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1507                 error("ssh_keysign: no installed: %s", strerror(errno));
1508                 return -1;
1509         }
1510         if (fflush(stdout) != 0)
1511                 error("ssh_keysign: fflush: %s", strerror(errno));
1512         if (pipe(to) < 0) {
1513                 error("ssh_keysign: pipe: %s", strerror(errno));
1514                 return -1;
1515         }
1516         if (pipe(from) < 0) {
1517                 error("ssh_keysign: pipe: %s", strerror(errno));
1518                 return -1;
1519         }
1520         if ((pid = fork()) < 0) {
1521                 error("ssh_keysign: fork: %s", strerror(errno));
1522                 return -1;
1523         }
1524         if (pid == 0) {
1525                 permanently_drop_suid(getuid());
1526                 close(from[0]);
1527                 if (dup2(from[1], STDOUT_FILENO) < 0)
1528                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1529                 close(to[1]);
1530                 if (dup2(to[0], STDIN_FILENO) < 0)
1531                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1532                 close(from[1]);
1533                 close(to[0]);
1534                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1535                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1536                     strerror(errno));
1537         }
1538         close(from[1]);
1539         close(to[0]);
1540
1541         buffer_init(&b);
1542         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1543         buffer_put_string(&b, data, datalen);
1544         if (ssh_msg_send(to[1], version, &b) == -1)
1545                 fatal("ssh_keysign: couldn't send request");
1546
1547         if (ssh_msg_recv(from[0], &b) < 0) {
1548                 error("ssh_keysign: no reply");
1549                 buffer_free(&b);
1550                 return -1;
1551         }
1552         close(from[0]);
1553         close(to[1]);
1554
1555         while (waitpid(pid, &status, 0) < 0)
1556                 if (errno != EINTR)
1557                         break;
1558
1559         if (buffer_get_char(&b) != version) {
1560                 error("ssh_keysign: bad version");
1561                 buffer_free(&b);
1562                 return -1;
1563         }
1564         *sigp = buffer_get_string(&b, lenp);
1565         buffer_free(&b);
1566
1567         return 0;
1568 }
1569
1570 int
1571 userauth_hostbased(Authctxt *authctxt)
1572 {
1573         Key *private = NULL;
1574         Sensitive *sensitive = authctxt->sensitive;
1575         Buffer b;
1576         u_char *signature, *blob;
1577         char *chost, *pkalg, *p, myname[NI_MAXHOST];
1578         const char *service;
1579         u_int blen, slen;
1580         int ok, i, len, found = 0;
1581
1582         /* check for a useful key */
1583         for (i = 0; i < sensitive->nkeys; i++) {
1584                 private = sensitive->keys[i];
1585                 if (private && private->type != KEY_RSA1) {
1586                         found = 1;
1587                         /* we take and free the key */
1588                         sensitive->keys[i] = NULL;
1589                         break;
1590                 }
1591         }
1592         if (!found) {
1593                 debug("No more client hostkeys for hostbased authentication.");
1594                 return 0;
1595         }
1596         if (key_to_blob(private, &blob, &blen) == 0) {
1597                 key_free(private);
1598                 return 0;
1599         }
1600         /* figure out a name for the client host */
1601         p = NULL;
1602         if (packet_connection_is_on_socket())
1603                 p = get_local_name(packet_get_connection_in());
1604         if (p == NULL) {
1605                 if (gethostname(myname, sizeof(myname)) == -1) {
1606                         verbose("userauth_hostbased: gethostname: %s",
1607                             strerror(errno));
1608                 } else
1609                         p = xstrdup(myname);
1610         }
1611         if (p == NULL) {
1612                 error("userauth_hostbased: cannot get local ipaddr/name");
1613                 key_free(private);
1614                 xfree(blob);
1615                 return 0;
1616         }
1617         len = strlen(p) + 2;
1618         xasprintf(&chost, "%s.", p);
1619         debug2("userauth_hostbased: chost %s", chost);
1620         xfree(p);
1621
1622         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1623             authctxt->service;
1624         pkalg = xstrdup(key_ssh_name(private));
1625         buffer_init(&b);
1626         /* construct data */
1627         buffer_put_string(&b, session_id2, session_id2_len);
1628         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1629         buffer_put_cstring(&b, authctxt->server_user);
1630         buffer_put_cstring(&b, service);
1631         buffer_put_cstring(&b, authctxt->method->name);
1632         buffer_put_cstring(&b, pkalg);
1633         buffer_put_string(&b, blob, blen);
1634         buffer_put_cstring(&b, chost);
1635         buffer_put_cstring(&b, authctxt->local_user);
1636 #ifdef DEBUG_PK
1637         buffer_dump(&b);
1638 #endif
1639         if (sensitive->external_keysign)
1640                 ok = ssh_keysign(private, &signature, &slen,
1641                     buffer_ptr(&b), buffer_len(&b));
1642         else
1643                 ok = key_sign(private, &signature, &slen,
1644                     buffer_ptr(&b), buffer_len(&b));
1645         key_free(private);
1646         buffer_free(&b);
1647         if (ok != 0) {
1648                 error("key_sign failed");
1649                 xfree(chost);
1650                 xfree(pkalg);
1651                 xfree(blob);
1652                 return 0;
1653         }
1654         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1655         packet_put_cstring(authctxt->server_user);
1656         packet_put_cstring(authctxt->service);
1657         packet_put_cstring(authctxt->method->name);
1658         packet_put_cstring(pkalg);
1659         packet_put_string(blob, blen);
1660         packet_put_cstring(chost);
1661         packet_put_cstring(authctxt->local_user);
1662         packet_put_string(signature, slen);
1663         memset(signature, 's', slen);
1664         xfree(signature);
1665         xfree(chost);
1666         xfree(pkalg);
1667         xfree(blob);
1668
1669         packet_send();
1670         return 1;
1671 }
1672
1673 #ifdef JPAKE
1674 int
1675 userauth_jpake(Authctxt *authctxt)
1676 {
1677         struct jpake_ctx *pctx;
1678         u_char *x1_proof, *x2_proof;
1679         u_int x1_proof_len, x2_proof_len;
1680         static int attempt = 0; /* XXX share with userauth_password's? */
1681
1682         if (attempt++ >= options.number_of_password_prompts)
1683                 return 0;
1684         if (attempt != 1)
1685                 error("Permission denied, please try again.");
1686
1687         if (authctxt->methoddata != NULL)
1688                 fatal("%s: authctxt->methoddata already set (%p)",
1689                     __func__, authctxt->methoddata);
1690
1691         authctxt->methoddata = pctx = jpake_new();
1692
1693         /*
1694          * Send request immediately, to get the protocol going while
1695          * we do the initial computations.
1696          */
1697         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1698         packet_put_cstring(authctxt->server_user);
1699         packet_put_cstring(authctxt->service);
1700         packet_put_cstring(authctxt->method->name);
1701         packet_send();
1702         packet_write_wait();
1703
1704         jpake_step1(pctx->grp,
1705             &pctx->client_id, &pctx->client_id_len,
1706             &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2,
1707             &x1_proof, &x1_proof_len,
1708             &x2_proof, &x2_proof_len);
1709
1710         JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__));
1711
1712         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1);
1713         packet_put_string(pctx->client_id, pctx->client_id_len);
1714         packet_put_bignum2(pctx->g_x1);
1715         packet_put_bignum2(pctx->g_x2);
1716         packet_put_string(x1_proof, x1_proof_len);
1717         packet_put_string(x2_proof, x2_proof_len);
1718         packet_send();
1719
1720         bzero(x1_proof, x1_proof_len);
1721         bzero(x2_proof, x2_proof_len);
1722         xfree(x1_proof);
1723         xfree(x2_proof);
1724
1725         /* Expect step 1 packet from peer */
1726         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1,
1727             input_userauth_jpake_server_step1);
1728         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS,
1729             &input_userauth_success_unexpected);
1730
1731         return 1;
1732 }
1733
1734 void
1735 userauth_jpake_cleanup(Authctxt *authctxt)
1736 {
1737         debug3("%s: clean up", __func__);
1738         if (authctxt->methoddata != NULL) {
1739                 jpake_free(authctxt->methoddata);
1740                 authctxt->methoddata = NULL;
1741         }
1742         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
1743 }
1744 #endif /* JPAKE */
1745
1746 /* find auth method */
1747
1748 /*
1749  * given auth method name, if configurable options permit this method fill
1750  * in auth_ident field and return true, otherwise return false.
1751  */
1752 static int
1753 authmethod_is_enabled(Authmethod *method)
1754 {
1755         if (method == NULL)
1756                 return 0;
1757         /* return false if options indicate this method is disabled */
1758         if  (method->enabled == NULL || *method->enabled == 0)
1759                 return 0;
1760         /* return false if batch mode is enabled but method needs interactive mode */
1761         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1762                 return 0;
1763         return 1;
1764 }
1765
1766 static Authmethod *
1767 authmethod_lookup(const char *name)
1768 {
1769         Authmethod *method = NULL;
1770         if (name != NULL)
1771                 for (method = authmethods; method->name != NULL; method++)
1772                         if (strcmp(name, method->name) == 0)
1773                                 return method;
1774         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1775         return NULL;
1776 }
1777
1778 /* XXX internal state */
1779 static Authmethod *current = NULL;
1780 static char *supported = NULL;
1781 static char *preferred = NULL;
1782
1783 /*
1784  * Given the authentication method list sent by the server, return the
1785  * next method we should try.  If the server initially sends a nil list,
1786  * use a built-in default list.
1787  */
1788 static Authmethod *
1789 authmethod_get(char *authlist)
1790 {
1791         char *name = NULL;
1792         u_int next;
1793
1794         /* Use a suitable default if we're passed a nil list.  */
1795         if (authlist == NULL || strlen(authlist) == 0)
1796                 authlist = options.preferred_authentications;
1797
1798         if (supported == NULL || strcmp(authlist, supported) != 0) {
1799                 debug3("start over, passed a different list %s", authlist);
1800                 if (supported != NULL)
1801                         xfree(supported);
1802                 supported = xstrdup(authlist);
1803                 preferred = options.preferred_authentications;
1804                 debug3("preferred %s", preferred);
1805                 current = NULL;
1806         } else if (current != NULL && authmethod_is_enabled(current))
1807                 return current;
1808
1809         for (;;) {
1810                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1811                         debug("No more authentication methods to try.");
1812                         current = NULL;
1813                         return NULL;
1814                 }
1815                 preferred += next;
1816                 debug3("authmethod_lookup %s", name);
1817                 debug3("remaining preferred: %s", preferred);
1818                 if ((current = authmethod_lookup(name)) != NULL &&
1819                     authmethod_is_enabled(current)) {
1820                         debug3("authmethod_is_enabled %s", name);
1821                         debug("Next authentication method: %s", name);
1822                         return current;
1823                 }
1824         }
1825 }
1826
1827 static char *
1828 authmethods_get(void)
1829 {
1830         Authmethod *method = NULL;
1831         Buffer b;
1832         char *list;
1833
1834         buffer_init(&b);
1835         for (method = authmethods; method->name != NULL; method++) {
1836                 if (authmethod_is_enabled(method)) {
1837                         if (buffer_len(&b) > 0)
1838                                 buffer_append(&b, ",", 1);
1839                         buffer_append(&b, method->name, strlen(method->name));
1840                 }
1841         }
1842         buffer_append(&b, "\0", 1);
1843         list = xstrdup(buffer_ptr(&b));
1844         buffer_free(&b);
1845         return list;
1846 }
1847