sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.178 2010/01/11 04:46:45 dtucker 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
  84 /*
  85  * SSH2 key exchange
  86  */
  87
  88 u_char *session_id2 = NULL;
  89 u_int session_id2_len = 0;
  90
  91 char *xxx_host;
  92 struct sockaddr *xxx_hostaddr;
  93
  94 Kex *xxx_kex = NULL;
  95
  96 static int
  97 verify_host_key_callback(Key *hostkey)
  98 {
  99         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
 100                 fatal("Host key verification failed.");
 101         return 0;
 102 }
 103
 104 void
 105 ssh_kex2(char *host, struct sockaddr *hostaddr)
 106 {
 107         Kex *kex;
 108
 109         xxx_host = host;
 110         xxx_hostaddr = hostaddr;
 111
 112         if (options.ciphers == (char *)-1) {
 113                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 114                 options.ciphers = NULL;
 115         }
 116         if (options.ciphers != NULL) {
 117                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 118                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 119         }
 120         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 121             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 122         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 123             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 124         if (options.compression) {
 125                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 126                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 127         } else {
 128                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 129                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 130         }
 131         if (options.macs != NULL) {
 132                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 133                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 134         }
 135         if (options.hostkeyalgorithms != NULL)
 136                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 137                     options.hostkeyalgorithms;
 138
 139         if (options.rekey_limit)
 140                 packet_set_rekey_limit((u_int32_t)options.rekey_limit);
 141
 142         /* start key exchange */
 143         kex = kex_setup(myproposal);
 144         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 145         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 146         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 147         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 148         kex->client_version_string=client_version_string;
 149         kex->server_version_string=server_version_string;
 150         kex->verify_host_key=&verify_host_key_callback;
 151
 152         xxx_kex = kex;
 153
 154         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 155
 156         if (options.use_roaming && !kex->roaming) {
 157                 debug("Roaming not allowed by server");
 158                 options.use_roaming = 0;
 159         }
 160
 161         session_id2 = kex->session_id;
 162         session_id2_len = kex->session_id_len;
 163
 164 #ifdef DEBUG_KEXDH
 165         /* send 1st encrypted/maced/compressed message */
 166         packet_start(SSH2_MSG_IGNORE);
 167         packet_put_cstring("markus");
 168         packet_send();
 169         packet_write_wait();
 170 #endif
 171 }
 172
 173 /*
 174  * Authenticate user
 175  */
 176
 177 typedef struct Authctxt Authctxt;
 178 typedef struct Authmethod Authmethod;
 179 typedef struct identity Identity;
 180 typedef struct idlist Idlist;
 181
 182 struct identity {
 183         TAILQ_ENTRY(identity) next;
 184         AuthenticationConnection *ac;   /* set if agent supports key */
 185         Key     *key;                   /* public/private key */
 186         char    *filename;              /* comment for agent-only keys */
 187         int     tried;
 188         int     isprivate;              /* key points to the private key */
 189 };
 190 TAILQ_HEAD(idlist, identity);
 191
 192 struct Authctxt {
 193         const char *server_user;
 194         const char *local_user;
 195         const char *host;
 196         const char *service;
 197         Authmethod *method;
 198         int success;
 199         char *authlist;
 200         /* pubkey */
 201         Idlist keys;
 202         AuthenticationConnection *agent;
 203         /* hostbased */
 204         Sensitive *sensitive;
 205         /* kbd-interactive */
 206         int info_req_seen;
 207         /* generic */
 208         void *methoddata;
 209 };
 210 struct Authmethod {
 211         char    *name;          /* string to compare against server's list */
 212         int     (*userauth)(Authctxt *authctxt);
 213         void    (*cleanup)(Authctxt *authctxt);
 214         int     *enabled;       /* flag in option struct that enables method */
 215         int     *batch_flag;    /* flag in option struct that disables method */
 216 };
 217
 218 void    input_userauth_success(int, u_int32_t, void *);
 219 void    input_userauth_success_unexpected(int, u_int32_t, void *);
 220 void    input_userauth_failure(int, u_int32_t, void *);
 221 void    input_userauth_banner(int, u_int32_t, void *);
 222 void    input_userauth_error(int, u_int32_t, void *);
 223 void    input_userauth_info_req(int, u_int32_t, void *);
 224 void    input_userauth_pk_ok(int, u_int32_t, void *);
 225 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 226 void    input_userauth_jpake_server_step1(int, u_int32_t, void *);
 227 void    input_userauth_jpake_server_step2(int, u_int32_t, void *);
 228 void    input_userauth_jpake_server_confirm(int, u_int32_t, void *);
 229
 230 int     userauth_none(Authctxt *);
 231 int     userauth_pubkey(Authctxt *);
 232 int     userauth_passwd(Authctxt *);
 233 int     userauth_kbdint(Authctxt *);
 234 int     userauth_hostbased(Authctxt *);
 235 int     userauth_jpake(Authctxt *);
 236
 237 void    userauth_jpake_cleanup(Authctxt *);
 238
 239 #ifdef GSSAPI
 240 int     userauth_gssapi(Authctxt *authctxt);
 241 void    input_gssapi_response(int type, u_int32_t, void *);
 242 void    input_gssapi_token(int type, u_int32_t, void *);
 243 void    input_gssapi_hash(int type, u_int32_t, void *);
 244 void    input_gssapi_error(int, u_int32_t, void *);
 245 void    input_gssapi_errtok(int, u_int32_t, void *);
 246 #endif
 247
 248 void    userauth(Authctxt *, char *);
 249
 250 static int sign_and_send_pubkey(Authctxt *, Identity *);
 251 static void pubkey_prepare(Authctxt *);
 252 static void pubkey_cleanup(Authctxt *);
 253 static Key *load_identity_file(char *);
 254
 255 static Authmethod *authmethod_get(char *authlist);
 256 static Authmethod *authmethod_lookup(const char *name);
 257 static char *authmethods_get(void);
 258
 259 Authmethod authmethods[] = {
 260 #ifdef GSSAPI
 261         {"gssapi-with-mic",
 262                 userauth_gssapi,
 263                 NULL,
 264                 &options.gss_authentication,
 265                 NULL},
 266 #endif
 267         {"hostbased",
 268                 userauth_hostbased,
 269                 NULL,
 270                 &options.hostbased_authentication,
 271                 NULL},
 272         {"publickey",
 273                 userauth_pubkey,
 274                 NULL,
 275                 &options.pubkey_authentication,
 276                 NULL},
 277 #ifdef JPAKE
 278         {"jpake-01@openssh.com",
 279                 userauth_jpake,
 280                 userauth_jpake_cleanup,
 281                 &options.zero_knowledge_password_authentication,
 282                 &options.batch_mode},
 283 #endif
 284         {"keyboard-interactive",
 285                 userauth_kbdint,
 286                 NULL,
 287                 &options.kbd_interactive_authentication,
 288                 &options.batch_mode},
 289         {"password",
 290                 userauth_passwd,
 291                 NULL,
 292                 &options.password_authentication,
 293                 &options.batch_mode},
 294         {"none",
 295                 userauth_none,
 296                 NULL,
 297                 NULL,
 298                 NULL},
 299         {NULL, NULL, NULL, NULL, NULL}
 300 };
 301
 302 void
 303 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 304     Sensitive *sensitive)
 305 {
 306         Authctxt authctxt;
 307         int type;
 308
 309         if (options.challenge_response_authentication)
 310                 options.kbd_interactive_authentication = 1;
 311
 312         packet_start(SSH2_MSG_SERVICE_REQUEST);
 313         packet_put_cstring("ssh-userauth");
 314         packet_send();
 315         debug("SSH2_MSG_SERVICE_REQUEST sent");
 316         packet_write_wait();
 317         type = packet_read();
 318         if (type != SSH2_MSG_SERVICE_ACCEPT)
 319                 fatal("Server denied authentication request: %d", type);
 320         if (packet_remaining() > 0) {
 321                 char *reply = packet_get_string(NULL);
 322                 debug2("service_accept: %s", reply);
 323                 xfree(reply);
 324         } else {
 325                 debug2("buggy server: service_accept w/o service");
 326         }
 327         packet_check_eom();
 328         debug("SSH2_MSG_SERVICE_ACCEPT received");
 329
 330         if (options.preferred_authentications == NULL)
 331                 options.preferred_authentications = authmethods_get();
 332
 333         /* setup authentication context */
 334         memset(&authctxt, 0, sizeof(authctxt));
 335         pubkey_prepare(&authctxt);
 336         authctxt.server_user = server_user;
 337         authctxt.local_user = local_user;
 338         authctxt.host = host;
 339         authctxt.service = "ssh-connection";            /* service name */
 340         authctxt.success = 0;
 341         authctxt.method = authmethod_lookup("none");
 342         authctxt.authlist = NULL;
 343         authctxt.methoddata = NULL;
 344         authctxt.sensitive = sensitive;
 345         authctxt.info_req_seen = 0;
 346         if (authctxt.method == NULL)
 347                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 348
 349         /* initial userauth request */
 350         userauth_none(&authctxt);
 351
 352         dispatch_init(&input_userauth_error);
 353         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 354         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 355         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 356         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 357
 358         pubkey_cleanup(&authctxt);
 359         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 360
 361         debug("Authentication succeeded (%s).", authctxt.method->name);
 362 }
 363
 364 void
 365 userauth(Authctxt *authctxt, char *authlist)
 366 {
 367         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 368                 authctxt->method->cleanup(authctxt);
 369
 370         if (authctxt->methoddata) {
 371                 xfree(authctxt->methoddata);
 372                 authctxt->methoddata = NULL;
 373         }
 374         if (authlist == NULL) {
 375                 authlist = authctxt->authlist;
 376         } else {
 377                 if (authctxt->authlist)
 378                         xfree(authctxt->authlist);
 379                 authctxt->authlist = authlist;
 380         }
 381         for (;;) {
 382                 Authmethod *method = authmethod_get(authlist);
 383                 if (method == NULL)
 384                         fatal("Permission denied (%s).", authlist);
 385                 authctxt->method = method;
 386
 387                 /* reset the per method handler */
 388                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 389                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 390
 391                 /* and try new method */
 392                 if (method->userauth(authctxt) != 0) {
 393                         debug2("we sent a %s packet, wait for reply", method->name);
 394                         break;
 395                 } else {
 396                         debug2("we did not send a packet, disable method");
 397                         method->enabled = NULL;
 398                 }
 399         }
 400 }
 401
 402 /* ARGSUSED */
 403 void
 404 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 405 {
 406         fatal("input_userauth_error: bad message during authentication: "
 407             "type %d", type);
 408 }
 409
 410 /* ARGSUSED */
 411 void
 412 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 413 {
 414         char *msg, *raw, *lang;
 415         u_int len;
 416
 417         debug3("input_userauth_banner");
 418         raw = packet_get_string(&len);
 419         lang = packet_get_string(NULL);
 420         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
 421                 if (len > 65536)
 422                         len = 65536;
 423                 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
 424                 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH);
 425                 fprintf(stderr, "%s", msg);
 426                 xfree(msg);
 427         }
 428         xfree(raw);
 429         xfree(lang);
 430 }
 431
 432 /* ARGSUSED */
 433 void
 434 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 435 {
 436         Authctxt *authctxt = ctxt;
 437
 438         if (authctxt == NULL)
 439                 fatal("input_userauth_success: no authentication context");
 440         if (authctxt->authlist) {
 441                 xfree(authctxt->authlist);
 442                 authctxt->authlist = NULL;
 443         }
 444         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 445                 authctxt->method->cleanup(authctxt);
 446         if (authctxt->methoddata) {
 447                 xfree(authctxt->methoddata);
 448                 authctxt->methoddata = NULL;
 449         }
 450         authctxt->success = 1;                  /* break out */
 451 }
 452
 453 void
 454 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
 455 {
 456         Authctxt *authctxt = ctxt;
 457
 458         if (authctxt == NULL)
 459                 fatal("%s: no authentication context", __func__);
 460
 461         fatal("Unexpected authentication success during %s.",
 462             authctxt->method->name);
 463 }
 464
 465 /* ARGSUSED */
 466 void
 467 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 468 {
 469         Authctxt *authctxt = ctxt;
 470         char *authlist = NULL;
 471         int partial;
 472
 473         if (authctxt == NULL)
 474                 fatal("input_userauth_failure: no authentication context");
 475
 476         authlist = packet_get_string(NULL);
 477         partial = packet_get_char();
 478         packet_check_eom();
 479
 480         if (partial != 0)
 481                 logit("Authenticated with partial success.");
 482         debug("Authentications that can continue: %s", authlist);
 483
 484         userauth(authctxt, authlist);
 485 }
 486
 487 /* ARGSUSED */
 488 void
 489 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 490 {
 491         Authctxt *authctxt = ctxt;
 492         Key *key = NULL;
 493         Identity *id = NULL;
 494         Buffer b;
 495         int pktype, sent = 0;
 496         u_int alen, blen;
 497         char *pkalg, *fp;
 498         u_char *pkblob;
 499
 500         if (authctxt == NULL)
 501                 fatal("input_userauth_pk_ok: no authentication context");
 502         if (datafellows & SSH_BUG_PKOK) {
 503                 /* this is similar to SSH_BUG_PKAUTH */
 504                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 505                 pkblob = packet_get_string(&blen);
 506                 buffer_init(&b);
 507                 buffer_append(&b, pkblob, blen);
 508                 pkalg = buffer_get_string(&b, &alen);
 509                 buffer_free(&b);
 510         } else {
 511                 pkalg = packet_get_string(&alen);
 512                 pkblob = packet_get_string(&blen);
 513         }
 514         packet_check_eom();
 515
 516         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 517
 518         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 519                 debug("unknown pkalg %s", pkalg);
 520                 goto done;
 521         }
 522         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 523                 debug("no key from blob. pkalg %s", pkalg);
 524                 goto done;
 525         }
 526         if (key->type != pktype) {
 527                 error("input_userauth_pk_ok: type mismatch "
 528                     "for decoded key (received %d, expected %d)",
 529                     key->type, pktype);
 530                 goto done;
 531         }
 532         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 533         debug2("input_userauth_pk_ok: fp %s", fp);
 534         xfree(fp);
 535
 536         /*
 537          * search keys in the reverse order, because last candidate has been
 538          * moved to the end of the queue.  this also avoids confusion by
 539          * duplicate keys
 540          */
 541         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 542                 if (key_equal(key, id->key)) {
 543                         sent = sign_and_send_pubkey(authctxt, id);
 544                         break;
 545                 }
 546         }
 547 done:
 548         if (key != NULL)
 549                 key_free(key);
 550         xfree(pkalg);
 551         xfree(pkblob);
 552
 553         /* try another method if we did not send a packet */
 554         if (sent == 0)
 555                 userauth(authctxt, NULL);
 556 }
 557
 558 #ifdef GSSAPI
 559 int
 560 userauth_gssapi(Authctxt *authctxt)
 561 {
 562         Gssctxt *gssctxt = NULL;
 563         static gss_OID_set gss_supported = NULL;
 564         static u_int mech = 0;
 565         OM_uint32 min;
 566         int ok = 0;
 567
 568         /* Try one GSSAPI method at a time, rather than sending them all at
 569          * once. */
 570
 571         if (gss_supported == NULL)
 572                 gss_indicate_mechs(&min, &gss_supported);
 573
 574         /* Check to see if the mechanism is usable before we offer it */
 575         while (mech < gss_supported->count && !ok) {
 576                 /* My DER encoding requires length<128 */
 577                 if (gss_supported->elements[mech].length < 128 &&
 578                     ssh_gssapi_check_mechanism(&gssctxt,
 579                     &gss_supported->elements[mech], authctxt->host)) {
 580                         ok = 1; /* Mechanism works */
 581                 } else {
 582                         mech++;
 583                 }
 584         }
 585
 586         if (!ok)
 587                 return 0;
 588
 589         authctxt->methoddata=(void *)gssctxt;
 590
 591         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 592         packet_put_cstring(authctxt->server_user);
 593         packet_put_cstring(authctxt->service);
 594         packet_put_cstring(authctxt->method->name);
 595
 596         packet_put_int(1);
 597
 598         packet_put_int((gss_supported->elements[mech].length) + 2);
 599         packet_put_char(SSH_GSS_OIDTYPE);
 600         packet_put_char(gss_supported->elements[mech].length);
 601         packet_put_raw(gss_supported->elements[mech].elements,
 602             gss_supported->elements[mech].length);
 603
 604         packet_send();
 605
 606         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 607         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 608         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 609         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 610
 611         mech++; /* Move along to next candidate */
 612
 613         return 1;
 614 }
 615
 616 static OM_uint32
 617 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 618 {
 619         Authctxt *authctxt = ctxt;
 620         Gssctxt *gssctxt = authctxt->methoddata;
 621         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 622         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 623         gss_buffer_desc gssbuf;
 624         OM_uint32 status, ms, flags;
 625         Buffer b;
 626
 627         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 628             recv_tok, &send_tok, &flags);
 629
 630         if (send_tok.length > 0) {
 631                 if (GSS_ERROR(status))
 632                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 633                 else
 634                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 635
 636                 packet_put_string(send_tok.value, send_tok.length);
 637                 packet_send();
 638                 gss_release_buffer(&ms, &send_tok);
 639         }
 640
 641         if (status == GSS_S_COMPLETE) {
 642                 /* send either complete or MIC, depending on mechanism */
 643                 if (!(flags & GSS_C_INTEG_FLAG)) {
 644                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 645                         packet_send();
 646                 } else {
 647                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 648                             authctxt->service, "gssapi-with-mic");
 649
 650                         gssbuf.value = buffer_ptr(&b);
 651                         gssbuf.length = buffer_len(&b);
 652
 653                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 654
 655                         if (!GSS_ERROR(status)) {
 656                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 657                                 packet_put_string(mic.value, mic.length);
 658
 659                                 packet_send();
 660                         }
 661
 662                         buffer_free(&b);
 663                         gss_release_buffer(&ms, &mic);
 664                 }
 665         }
 666
 667         return status;
 668 }
 669
 670 /* ARGSUSED */
 671 void
 672 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 673 {
 674         Authctxt *authctxt = ctxt;
 675         Gssctxt *gssctxt;
 676         int oidlen;
 677         char *oidv;
 678
 679         if (authctxt == NULL)
 680                 fatal("input_gssapi_response: no authentication context");
 681         gssctxt = authctxt->methoddata;
 682
 683         /* Setup our OID */
 684         oidv = packet_get_string(&oidlen);
 685
 686         if (oidlen <= 2 ||
 687             oidv[0] != SSH_GSS_OIDTYPE ||
 688             oidv[1] != oidlen - 2) {
 689                 xfree(oidv);
 690                 debug("Badly encoded mechanism OID received");
 691                 userauth(authctxt, NULL);
 692                 return;
 693         }
 694
 695         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 696                 fatal("Server returned different OID than expected");
 697
 698         packet_check_eom();
 699
 700         xfree(oidv);
 701
 702         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 703                 /* Start again with next method on list */
 704                 debug("Trying to start again");
 705                 userauth(authctxt, NULL);
 706                 return;
 707         }
 708 }
 709
 710 /* ARGSUSED */
 711 void
 712 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 713 {
 714         Authctxt *authctxt = ctxt;
 715         gss_buffer_desc recv_tok;
 716         OM_uint32 status;
 717         u_int slen;
 718
 719         if (authctxt == NULL)
 720                 fatal("input_gssapi_response: no authentication context");
 721
 722         recv_tok.value = packet_get_string(&slen);
 723         recv_tok.length = slen; /* safe typecast */
 724
 725         packet_check_eom();
 726
 727         status = process_gssapi_token(ctxt, &recv_tok);
 728
 729         xfree(recv_tok.value);
 730
 731         if (GSS_ERROR(status)) {
 732                 /* Start again with the next method in the list */
 733                 userauth(authctxt, NULL);
 734                 return;
 735         }
 736 }
 737
 738 /* ARGSUSED */
 739 void
 740 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 741 {
 742         Authctxt *authctxt = ctxt;
 743         Gssctxt *gssctxt;
 744         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 745         gss_buffer_desc recv_tok;
 746         OM_uint32 status, ms;
 747         u_int len;
 748
 749         if (authctxt == NULL)
 750                 fatal("input_gssapi_response: no authentication context");
 751         gssctxt = authctxt->methoddata;
 752
 753         recv_tok.value = packet_get_string(&len);
 754         recv_tok.length = len;
 755
 756         packet_check_eom();
 757
 758         /* Stick it into GSSAPI and see what it says */
 759         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 760             &recv_tok, &send_tok, NULL);
 761
 762         xfree(recv_tok.value);
 763         gss_release_buffer(&ms, &send_tok);
 764
 765         /* Server will be returning a failed packet after this one */
 766 }
 767
 768 /* ARGSUSED */
 769 void
 770 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 771 {
 772         OM_uint32 maj, min;
 773         char *msg;
 774         char *lang;
 775
 776         maj=packet_get_int();
 777         min=packet_get_int();
 778         msg=packet_get_string(NULL);
 779         lang=packet_get_string(NULL);
 780
 781         packet_check_eom();
 782
 783         debug("Server GSSAPI Error:\n%s", msg);
 784         xfree(msg);
 785         xfree(lang);
 786 }
 787 #endif /* GSSAPI */
 788
 789 int
 790 userauth_none(Authctxt *authctxt)
 791 {
 792         /* initial userauth request */
 793         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 794         packet_put_cstring(authctxt->server_user);
 795         packet_put_cstring(authctxt->service);
 796         packet_put_cstring(authctxt->method->name);
 797         packet_send();
 798         return 1;
 799 }
 800
 801 int
 802 userauth_passwd(Authctxt *authctxt)
 803 {
 804         static int attempt = 0;
 805         char prompt[150];
 806         char *password;
 807         const char *host = options.host_key_alias ?  options.host_key_alias :
 808             authctxt->host;
 809
 810         if (attempt++ >= options.number_of_password_prompts)
 811                 return 0;
 812
 813         if (attempt != 1)
 814                 error("Permission denied, please try again.");
 815
 816         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 817             authctxt->server_user, host);
 818         password = read_passphrase(prompt, 0);
 819         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 820         packet_put_cstring(authctxt->server_user);
 821         packet_put_cstring(authctxt->service);
 822         packet_put_cstring(authctxt->method->name);
 823         packet_put_char(0);
 824         packet_put_cstring(password);
 825         memset(password, 0, strlen(password));
 826         xfree(password);
 827         packet_add_padding(64);
 828         packet_send();
 829
 830         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 831             &input_userauth_passwd_changereq);
 832
 833         return 1;
 834 }
 835
 836 /*
 837  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 838  */
 839 /* ARGSUSED */
 840 void
 841 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 842 {
 843         Authctxt *authctxt = ctxt;
 844         char *info, *lang, *password = NULL, *retype = NULL;
 845         char prompt[150];
 846         const char *host = options.host_key_alias ? options.host_key_alias :
 847             authctxt->host;
 848
 849         debug2("input_userauth_passwd_changereq");
 850
 851         if (authctxt == NULL)
 852                 fatal("input_userauth_passwd_changereq: "
 853                     "no authentication context");
 854
 855         info = packet_get_string(NULL);
 856         lang = packet_get_string(NULL);
 857         if (strlen(info) > 0)
 858                 logit("%s", info);
 859         xfree(info);
 860         xfree(lang);
 861         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 862         packet_put_cstring(authctxt->server_user);
 863         packet_put_cstring(authctxt->service);
 864         packet_put_cstring(authctxt->method->name);
 865         packet_put_char(1);                     /* additional info */
 866         snprintf(prompt, sizeof(prompt),
 867             "Enter %.30s@%.128s's old password: ",
 868             authctxt->server_user, host);
 869         password = read_passphrase(prompt, 0);
 870         packet_put_cstring(password);
 871         memset(password, 0, strlen(password));
 872         xfree(password);
 873         password = NULL;
 874         while (password == NULL) {
 875                 snprintf(prompt, sizeof(prompt),
 876                     "Enter %.30s@%.128s's new password: ",
 877                     authctxt->server_user, host);
 878                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 879                 if (password == NULL) {
 880                         /* bail out */
 881                         return;
 882                 }
 883                 snprintf(prompt, sizeof(prompt),
 884                     "Retype %.30s@%.128s's new password: ",
 885                     authctxt->server_user, host);
 886                 retype = read_passphrase(prompt, 0);
 887                 if (strcmp(password, retype) != 0) {
 888                         memset(password, 0, strlen(password));
 889                         xfree(password);
 890                         logit("Mismatch; try again, EOF to quit.");
 891                         password = NULL;
 892                 }
 893                 memset(retype, 0, strlen(retype));
 894                 xfree(retype);
 895         }
 896         packet_put_cstring(password);
 897         memset(password, 0, strlen(password));
 898         xfree(password);
 899         packet_add_padding(64);
 900         packet_send();
 901
 902         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 903             &input_userauth_passwd_changereq);
 904 }
 905
 906 #ifdef JPAKE
 907 static char *
 908 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt)
 909 {
 910         /* OpenBSD crypt(3) handles all of these */
 911         if (strcmp(crypt_scheme, "crypt") == 0 ||
 912             strcmp(crypt_scheme, "bcrypt") == 0 ||
 913             strcmp(crypt_scheme, "md5crypt") == 0 ||
 914             strcmp(crypt_scheme, "crypt-extended") == 0)
 915                 return xstrdup(crypt(password, salt));
 916         error("%s: unsupported password encryption scheme \"%.100s\"",
 917             __func__, crypt_scheme);
 918         return NULL;
 919 }
 920
 921 static BIGNUM *
 922 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme,
 923     const char *salt)
 924 {
 925         char prompt[256], *password, *crypted;
 926         u_char *secret;
 927         u_int secret_len;
 928         BIGNUM *ret;
 929
 930         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ",
 931             authctxt->server_user, authctxt->host);
 932         password = read_passphrase(prompt, 0);
 933
 934         if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) {
 935                 logit("Disabling %s authentication", authctxt->method->name);
 936                 authctxt->method->enabled = NULL;
 937                 /* Continue with an empty password to fail gracefully */
 938                 crypted = xstrdup("");
 939         }
 940
 941 #ifdef JPAKE_DEBUG
 942         debug3("%s: salt = %s", __func__, salt);
 943         debug3("%s: scheme = %s", __func__, crypt_scheme);
 944         debug3("%s: crypted = %s", __func__, crypted);
 945 #endif
 946
 947         if (hash_buffer(crypted, strlen(crypted), EVP_sha256(),
 948             &secret, &secret_len) != 0)
 949                 fatal("%s: hash_buffer", __func__);
 950
 951         bzero(password, strlen(password));
 952         bzero(crypted, strlen(crypted));
 953         xfree(password);
 954         xfree(crypted);
 955
 956         if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL)
 957                 fatal("%s: BN_bin2bn (secret)", __func__);
 958         bzero(secret, secret_len);
 959         xfree(secret);
 960
 961         return ret;
 962 }
 963
 964 /* ARGSUSED */
 965 void
 966 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt)
 967 {
 968         Authctxt *authctxt = ctxt;
 969         struct jpake_ctx *pctx = authctxt->methoddata;
 970         u_char *x3_proof, *x4_proof, *x2_s_proof;
 971         u_int x3_proof_len, x4_proof_len, x2_s_proof_len;
 972         char *crypt_scheme, *salt;
 973
 974         /* Disable this message */
 975         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL);
 976
 977         if ((pctx->g_x3 = BN_new()) == NULL ||
 978             (pctx->g_x4 = BN_new()) == NULL)
 979                 fatal("%s: BN_new", __func__);
 980
 981         /* Fetch step 1 values */
 982         crypt_scheme = packet_get_string(NULL);
 983         salt = packet_get_string(NULL);
 984         pctx->server_id = packet_get_string(&pctx->server_id_len);
 985         packet_get_bignum2(pctx->g_x3);
 986         packet_get_bignum2(pctx->g_x4);
 987         x3_proof = packet_get_string(&x3_proof_len);
 988         x4_proof = packet_get_string(&x4_proof_len);
 989         packet_check_eom();
 990
 991         JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__));
 992
 993         /* Obtain password and derive secret */
 994         pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt);
 995         bzero(crypt_scheme, strlen(crypt_scheme));
 996         bzero(salt, strlen(salt));
 997         xfree(crypt_scheme);
 998         xfree(salt);
 999         JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__));
1000
1001         /* Calculate step 2 values */
1002         jpake_step2(pctx->grp, pctx->s, pctx->g_x1,
1003             pctx->g_x3, pctx->g_x4, pctx->x2,
1004             pctx->server_id, pctx->server_id_len,
1005             pctx->client_id, pctx->client_id_len,
1006             x3_proof, x3_proof_len,
1007             x4_proof, x4_proof_len,
1008             &pctx->a,
1009             &x2_s_proof, &x2_s_proof_len);
1010
1011         bzero(x3_proof, x3_proof_len);
1012         bzero(x4_proof, x4_proof_len);
1013         xfree(x3_proof);
1014         xfree(x4_proof);
1015
1016         JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__));
1017
1018         /* Send values for step 2 */
1019         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2);
1020         packet_put_bignum2(pctx->a);
1021         packet_put_string(x2_s_proof, x2_s_proof_len);
1022         packet_send();
1023
1024         bzero(x2_s_proof, x2_s_proof_len);
1025         xfree(x2_s_proof);
1026
1027         /* Expect step 2 packet from peer */
1028         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2,
1029             input_userauth_jpake_server_step2);
1030 }
1031
1032 /* ARGSUSED */
1033 void
1034 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt)
1035 {
1036         Authctxt *authctxt = ctxt;
1037         struct jpake_ctx *pctx = authctxt->methoddata;
1038         u_char *x4_s_proof;
1039         u_int x4_s_proof_len;
1040
1041         /* Disable this message */
1042         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL);
1043
1044         if ((pctx->b = BN_new()) == NULL)
1045                 fatal("%s: BN_new", __func__);
1046
1047         /* Fetch step 2 values */
1048         packet_get_bignum2(pctx->b);
1049         x4_s_proof = packet_get_string(&x4_s_proof_len);
1050         packet_check_eom();
1051
1052         JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__));
1053
1054         /* Derive shared key and calculate confirmation hash */
1055         jpake_key_confirm(pctx->grp, pctx->s, pctx->b,
1056             pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4,
1057             pctx->client_id, pctx->client_id_len,
1058             pctx->server_id, pctx->server_id_len,
1059             session_id2, session_id2_len,
1060             x4_s_proof, x4_s_proof_len,
1061             &pctx->k,
1062             &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len);
1063
1064         bzero(x4_s_proof, x4_s_proof_len);
1065         xfree(x4_s_proof);
1066
1067         JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__));
1068
1069         /* Send key confirmation proof */
1070         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM);
1071         packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len);
1072         packet_send();
1073
1074         /* Expect confirmation from peer */
1075         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM,
1076             input_userauth_jpake_server_confirm);
1077 }
1078
1079 /* ARGSUSED */
1080 void
1081 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt)
1082 {
1083         Authctxt *authctxt = ctxt;
1084         struct jpake_ctx *pctx = authctxt->methoddata;
1085
1086         /* Disable this message */
1087         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL);
1088
1089         pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len);
1090         packet_check_eom();
1091
1092         JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__));
1093
1094         /* Verify expected confirmation hash */
1095         if (jpake_check_confirm(pctx->k,
1096             pctx->server_id, pctx->server_id_len,
1097             session_id2, session_id2_len,
1098             pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1)
1099                 debug("%s: %s success", __func__, authctxt->method->name);
1100         else {
1101                 debug("%s: confirmation mismatch", __func__);
1102                 /* XXX stash this so if auth succeeds then we can warn/kill */
1103         }
1104
1105         userauth_jpake_cleanup(authctxt);
1106 }
1107 #endif /* JPAKE */
1108
1109 static int
1110 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
1111     u_char *data, u_int datalen)
1112 {
1113         Key *prv;
1114         int ret;
1115
1116         /* the agent supports this key */
1117         if (id->ac)
1118                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1119                     data, datalen));
1120         /*
1121          * we have already loaded the private key or
1122          * the private key is stored in external hardware
1123          */
1124         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1125                 return (key_sign(id->key, sigp, lenp, data, datalen));
1126         /* load the private key from the file */
1127         if ((prv = load_identity_file(id->filename)) == NULL)
1128                 return (-1);
1129         ret = key_sign(prv, sigp, lenp, data, datalen);
1130         key_free(prv);
1131         return (ret);
1132 }
1133
1134 static int
1135 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1136 {
1137         Buffer b;
1138         u_char *blob, *signature;
1139         u_int bloblen, slen;
1140         u_int skip = 0;
1141         int ret = -1;
1142         int have_sig = 1;
1143
1144         debug3("sign_and_send_pubkey");
1145
1146         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1147                 /* we cannot handle this key */
1148                 debug3("sign_and_send_pubkey: cannot handle key");
1149                 return 0;
1150         }
1151         /* data to be signed */
1152         buffer_init(&b);
1153         if (datafellows & SSH_OLD_SESSIONID) {
1154                 buffer_append(&b, session_id2, session_id2_len);
1155                 skip = session_id2_len;
1156         } else {
1157                 buffer_put_string(&b, session_id2, session_id2_len);
1158                 skip = buffer_len(&b);
1159         }
1160         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1161         buffer_put_cstring(&b, authctxt->server_user);
1162         buffer_put_cstring(&b,
1163             datafellows & SSH_BUG_PKSERVICE ?
1164             "ssh-userauth" :
1165             authctxt->service);
1166         if (datafellows & SSH_BUG_PKAUTH) {
1167                 buffer_put_char(&b, have_sig);
1168         } else {
1169                 buffer_put_cstring(&b, authctxt->method->name);
1170                 buffer_put_char(&b, have_sig);
1171                 buffer_put_cstring(&b, key_ssh_name(id->key));
1172         }
1173         buffer_put_string(&b, blob, bloblen);
1174
1175         /* generate signature */
1176         ret = identity_sign(id, &signature, &slen,
1177             buffer_ptr(&b), buffer_len(&b));
1178         if (ret == -1) {
1179                 xfree(blob);
1180                 buffer_free(&b);
1181                 return 0;
1182         }
1183 #ifdef DEBUG_PK
1184         buffer_dump(&b);
1185 #endif
1186         if (datafellows & SSH_BUG_PKSERVICE) {
1187                 buffer_clear(&b);
1188                 buffer_append(&b, session_id2, session_id2_len);
1189                 skip = session_id2_len;
1190                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1191                 buffer_put_cstring(&b, authctxt->server_user);
1192                 buffer_put_cstring(&b, authctxt->service);
1193                 buffer_put_cstring(&b, authctxt->method->name);
1194                 buffer_put_char(&b, have_sig);
1195                 if (!(datafellows & SSH_BUG_PKAUTH))
1196                         buffer_put_cstring(&b, key_ssh_name(id->key));
1197                 buffer_put_string(&b, blob, bloblen);
1198         }
1199         xfree(blob);
1200
1201         /* append signature */
1202         buffer_put_string(&b, signature, slen);
1203         xfree(signature);
1204
1205         /* skip session id and packet type */
1206         if (buffer_len(&b) < skip + 1)
1207                 fatal("userauth_pubkey: internal error");
1208         buffer_consume(&b, skip + 1);
1209
1210         /* put remaining data from buffer into packet */
1211         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1212         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1213         buffer_free(&b);
1214         packet_send();
1215
1216         return 1;
1217 }
1218
1219 static int
1220 send_pubkey_test(Authctxt *authctxt, Identity *id)
1221 {
1222         u_char *blob;
1223         u_int bloblen, have_sig = 0;
1224
1225         debug3("send_pubkey_test");
1226
1227         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1228                 /* we cannot handle this key */
1229                 debug3("send_pubkey_test: cannot handle key");
1230                 return 0;
1231         }
1232         /* register callback for USERAUTH_PK_OK message */
1233         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1234
1235         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1236         packet_put_cstring(authctxt->server_user);
1237         packet_put_cstring(authctxt->service);
1238         packet_put_cstring(authctxt->method->name);
1239         packet_put_char(have_sig);
1240         if (!(datafellows & SSH_BUG_PKAUTH))
1241                 packet_put_cstring(key_ssh_name(id->key));
1242         packet_put_string(blob, bloblen);
1243         xfree(blob);
1244         packet_send();
1245         return 1;
1246 }
1247
1248 static Key *
1249 load_identity_file(char *filename)
1250 {
1251         Key *private;
1252         char prompt[300], *passphrase;
1253         int perm_ok = 0, quit, i;
1254         struct stat st;
1255
1256         if (stat(filename, &st) < 0) {
1257                 debug3("no such identity: %s", filename);
1258                 return NULL;
1259         }
1260         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1261         if (!perm_ok)
1262                 return NULL;
1263         if (private == NULL) {
1264                 if (options.batch_mode)
1265                         return NULL;
1266                 snprintf(prompt, sizeof prompt,
1267                     "Enter passphrase for key '%.100s': ", filename);
1268                 for (i = 0; i < options.number_of_password_prompts; i++) {
1269                         passphrase = read_passphrase(prompt, 0);
1270                         if (strcmp(passphrase, "") != 0) {
1271                                 private = key_load_private_type(KEY_UNSPEC,
1272                                     filename, passphrase, NULL, NULL);
1273                                 quit = 0;
1274                         } else {
1275                                 debug2("no passphrase given, try next key");
1276                                 quit = 1;
1277                         }
1278                         memset(passphrase, 0, strlen(passphrase));
1279                         xfree(passphrase);
1280                         if (private != NULL || quit)
1281                                 break;
1282                         debug2("bad passphrase given, try again...");
1283                 }
1284         }
1285         return private;
1286 }
1287
1288 /*
1289  * try keys in the following order:
1290  *      1. agent keys that are found in the config file
1291  *      2. other agent keys
1292  *      3. keys that are only listed in the config file
1293  */
1294 static void
1295 pubkey_prepare(Authctxt *authctxt)
1296 {
1297         Identity *id;
1298         Idlist agent, files, *preferred;
1299         Key *key;
1300         AuthenticationConnection *ac;
1301         char *comment;
1302         int i, found;
1303
1304         TAILQ_INIT(&agent);     /* keys from the agent */
1305         TAILQ_INIT(&files);     /* keys from the config file */
1306         preferred = &authctxt->keys;
1307         TAILQ_INIT(preferred);  /* preferred order of keys */
1308
1309         /* list of keys stored in the filesystem */
1310         for (i = 0; i < options.num_identity_files; i++) {
1311                 key = options.identity_keys[i];
1312                 if (key && key->type == KEY_RSA1)
1313                         continue;
1314                 options.identity_keys[i] = NULL;
1315                 id = xcalloc(1, sizeof(*id));
1316                 id->key = key;
1317                 id->filename = xstrdup(options.identity_files[i]);
1318                 TAILQ_INSERT_TAIL(&files, id, next);
1319         }
1320         /* list of keys supported by the agent */
1321         if ((ac = ssh_get_authentication_connection())) {
1322                 for (key = ssh_get_first_identity(ac, &comment, 2);
1323                     key != NULL;
1324                     key = ssh_get_next_identity(ac, &comment, 2)) {
1325                         found = 0;
1326                         TAILQ_FOREACH(id, &files, next) {
1327                                 /* agent keys from the config file are preferred */
1328                                 if (key_equal(key, id->key)) {
1329                                         key_free(key);
1330                                         xfree(comment);
1331                                         TAILQ_REMOVE(&files, id, next);
1332                                         TAILQ_INSERT_TAIL(preferred, id, next);
1333                                         id->ac = ac;
1334                                         found = 1;
1335                                         break;
1336                                 }
1337                         }
1338                         if (!found && !options.identities_only) {
1339                                 id = xcalloc(1, sizeof(*id));
1340                                 id->key = key;
1341                                 id->filename = comment;
1342                                 id->ac = ac;
1343                                 TAILQ_INSERT_TAIL(&agent, id, next);
1344                         }
1345                 }
1346                 /* append remaining agent keys */
1347                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1348                         TAILQ_REMOVE(&agent, id, next);
1349                         TAILQ_INSERT_TAIL(preferred, id, next);
1350                 }
1351                 authctxt->agent = ac;
1352         }
1353         /* append remaining keys from the config file */
1354         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1355                 TAILQ_REMOVE(&files, id, next);
1356                 TAILQ_INSERT_TAIL(preferred, id, next);
1357         }
1358         TAILQ_FOREACH(id, preferred, next) {
1359                 debug2("key: %s (%p)", id->filename, id->key);
1360         }
1361 }
1362
1363 static void
1364 pubkey_cleanup(Authctxt *authctxt)
1365 {
1366         Identity *id;
1367
1368         if (authctxt->agent != NULL)
1369                 ssh_close_authentication_connection(authctxt->agent);
1370         for (id = TAILQ_FIRST(&authctxt->keys); id;
1371             id = TAILQ_FIRST(&authctxt->keys)) {
1372                 TAILQ_REMOVE(&authctxt->keys, id, next);
1373                 if (id->key)
1374                         key_free(id->key);
1375                 if (id->filename)
1376                         xfree(id->filename);
1377                 xfree(id);
1378         }
1379 }
1380
1381 int
1382 userauth_pubkey(Authctxt *authctxt)
1383 {
1384         Identity *id;
1385         int sent = 0;
1386
1387         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1388                 if (id->tried++)
1389                         return (0);
1390                 /* move key to the end of the queue */
1391                 TAILQ_REMOVE(&authctxt->keys, id, next);
1392                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1393                 /*
1394                  * send a test message if we have the public key. for
1395                  * encrypted keys we cannot do this and have to load the
1396                  * private key instead
1397                  */
1398                 if (id->key && id->key->type != KEY_RSA1) {
1399                         debug("Offering public key: %s", id->filename);
1400                         sent = send_pubkey_test(authctxt, id);
1401                 } else if (id->key == NULL) {
1402                         debug("Trying private key: %s", id->filename);
1403                         id->key = load_identity_file(id->filename);
1404                         if (id->key != NULL) {
1405                                 id->isprivate = 1;
1406                                 sent = sign_and_send_pubkey(authctxt, id);
1407                                 key_free(id->key);
1408                                 id->key = NULL;
1409                         }
1410                 }
1411                 if (sent)
1412                         return (sent);
1413         }
1414         return (0);
1415 }
1416
1417 /*
1418  * Send userauth request message specifying keyboard-interactive method.
1419  */
1420 int
1421 userauth_kbdint(Authctxt *authctxt)
1422 {
1423         static int attempt = 0;
1424
1425         if (attempt++ >= options.number_of_password_prompts)
1426                 return 0;
1427         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1428         if (attempt > 1 && !authctxt->info_req_seen) {
1429                 debug3("userauth_kbdint: disable: no info_req_seen");
1430                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1431                 return 0;
1432         }
1433
1434         debug2("userauth_kbdint");
1435         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1436         packet_put_cstring(authctxt->server_user);
1437         packet_put_cstring(authctxt->service);
1438         packet_put_cstring(authctxt->method->name);
1439         packet_put_cstring("");                                 /* lang */
1440         packet_put_cstring(options.kbd_interactive_devices ?
1441             options.kbd_interactive_devices : "");
1442         packet_send();
1443
1444         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1445         return 1;
1446 }
1447
1448 /*
1449  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1450  */
1451 void
1452 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1453 {
1454         Authctxt *authctxt = ctxt;
1455         char *name, *inst, *lang, *prompt, *response;
1456         u_int num_prompts, i;
1457         int echo = 0;
1458
1459         debug2("input_userauth_info_req");
1460
1461         if (authctxt == NULL)
1462                 fatal("input_userauth_info_req: no authentication context");
1463
1464         authctxt->info_req_seen = 1;
1465
1466         name = packet_get_string(NULL);
1467         inst = packet_get_string(NULL);
1468         lang = packet_get_string(NULL);
1469         if (strlen(name) > 0)
1470                 logit("%s", name);
1471         if (strlen(inst) > 0)
1472                 logit("%s", inst);
1473         xfree(name);
1474         xfree(inst);
1475         xfree(lang);
1476
1477         num_prompts = packet_get_int();
1478         /*
1479          * Begin to build info response packet based on prompts requested.
1480          * We commit to providing the correct number of responses, so if
1481          * further on we run into a problem that prevents this, we have to
1482          * be sure and clean this up and send a correct error response.
1483          */
1484         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1485         packet_put_int(num_prompts);
1486
1487         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1488         for (i = 0; i < num_prompts; i++) {
1489                 prompt = packet_get_string(NULL);
1490                 echo = packet_get_char();
1491
1492                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1493
1494                 packet_put_cstring(response);
1495                 memset(response, 0, strlen(response));
1496                 xfree(response);
1497                 xfree(prompt);
1498         }
1499         packet_check_eom(); /* done with parsing incoming message. */
1500
1501         packet_add_padding(64);
1502         packet_send();
1503 }
1504
1505 static int
1506 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1507     u_char *data, u_int datalen)
1508 {
1509         Buffer b;
1510         struct stat st;
1511         pid_t pid;
1512         int to[2], from[2], status, version = 2;
1513
1514         debug2("ssh_keysign called");
1515
1516         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1517                 error("ssh_keysign: no installed: %s", strerror(errno));
1518                 return -1;
1519         }
1520         if (fflush(stdout) != 0)
1521                 error("ssh_keysign: fflush: %s", strerror(errno));
1522         if (pipe(to) < 0) {
1523                 error("ssh_keysign: pipe: %s", strerror(errno));
1524                 return -1;
1525         }
1526         if (pipe(from) < 0) {
1527                 error("ssh_keysign: pipe: %s", strerror(errno));
1528                 return -1;
1529         }
1530         if ((pid = fork()) < 0) {
1531                 error("ssh_keysign: fork: %s", strerror(errno));
1532                 return -1;
1533         }
1534         if (pid == 0) {
1535                 /* keep the socket on exec */
1536                 fcntl(packet_get_connection_in(), F_SETFD, 0);
1537                 permanently_drop_suid(getuid());
1538                 close(from[0]);
1539                 if (dup2(from[1], STDOUT_FILENO) < 0)
1540                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1541                 close(to[1]);
1542                 if (dup2(to[0], STDIN_FILENO) < 0)
1543                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1544                 close(from[1]);
1545                 close(to[0]);
1546                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1547                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1548                     strerror(errno));
1549         }
1550         close(from[1]);
1551         close(to[0]);
1552
1553         buffer_init(&b);
1554         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1555         buffer_put_string(&b, data, datalen);
1556         if (ssh_msg_send(to[1], version, &b) == -1)
1557                 fatal("ssh_keysign: couldn't send request");
1558
1559         if (ssh_msg_recv(from[0], &b) < 0) {
1560                 error("ssh_keysign: no reply");
1561                 buffer_free(&b);
1562                 return -1;
1563         }
1564         close(from[0]);
1565         close(to[1]);
1566
1567         while (waitpid(pid, &status, 0) < 0)
1568                 if (errno != EINTR)
1569                         break;
1570
1571         if (buffer_get_char(&b) != version) {
1572                 error("ssh_keysign: bad version");
1573                 buffer_free(&b);
1574                 return -1;
1575         }
1576         *sigp = buffer_get_string(&b, lenp);
1577         buffer_free(&b);
1578
1579         return 0;
1580 }
1581
1582 int
1583 userauth_hostbased(Authctxt *authctxt)
1584 {
1585         Key *private = NULL;
1586         Sensitive *sensitive = authctxt->sensitive;
1587         Buffer b;
1588         u_char *signature, *blob;
1589         char *chost, *pkalg, *p, myname[NI_MAXHOST];
1590         const char *service;
1591         u_int blen, slen;
1592         int ok, i, found = 0;
1593
1594         /* check for a useful key */
1595         for (i = 0; i < sensitive->nkeys; i++) {
1596                 private = sensitive->keys[i];
1597                 if (private && private->type != KEY_RSA1) {
1598                         found = 1;
1599                         /* we take and free the key */
1600                         sensitive->keys[i] = NULL;
1601                         break;
1602                 }
1603         }
1604         if (!found) {
1605                 debug("No more client hostkeys for hostbased authentication.");
1606                 return 0;
1607         }
1608         if (key_to_blob(private, &blob, &blen) == 0) {
1609                 key_free(private);
1610                 return 0;
1611         }
1612         /* figure out a name for the client host */
1613         p = NULL;
1614         if (packet_connection_is_on_socket())
1615                 p = get_local_name(packet_get_connection_in());
1616         if (p == NULL) {
1617                 if (gethostname(myname, sizeof(myname)) == -1) {
1618                         verbose("userauth_hostbased: gethostname: %s",
1619                             strerror(errno));
1620                 } else
1621                         p = xstrdup(myname);
1622         }
1623         if (p == NULL) {
1624                 error("userauth_hostbased: cannot get local ipaddr/name");
1625                 key_free(private);
1626                 xfree(blob);
1627                 return 0;
1628         }
1629         xasprintf(&chost, "%s.", p);
1630         debug2("userauth_hostbased: chost %s", chost);
1631         xfree(p);
1632
1633         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1634             authctxt->service;
1635         pkalg = xstrdup(key_ssh_name(private));
1636         buffer_init(&b);
1637         /* construct data */
1638         buffer_put_string(&b, session_id2, session_id2_len);
1639         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1640         buffer_put_cstring(&b, authctxt->server_user);
1641         buffer_put_cstring(&b, service);
1642         buffer_put_cstring(&b, authctxt->method->name);
1643         buffer_put_cstring(&b, pkalg);
1644         buffer_put_string(&b, blob, blen);
1645         buffer_put_cstring(&b, chost);
1646         buffer_put_cstring(&b, authctxt->local_user);
1647 #ifdef DEBUG_PK
1648         buffer_dump(&b);
1649 #endif
1650         if (sensitive->external_keysign)
1651                 ok = ssh_keysign(private, &signature, &slen,
1652                     buffer_ptr(&b), buffer_len(&b));
1653         else
1654                 ok = key_sign(private, &signature, &slen,
1655                     buffer_ptr(&b), buffer_len(&b));
1656         key_free(private);
1657         buffer_free(&b);
1658         if (ok != 0) {
1659                 error("key_sign failed");
1660                 xfree(chost);
1661                 xfree(pkalg);
1662                 xfree(blob);
1663                 return 0;
1664         }
1665         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1666         packet_put_cstring(authctxt->server_user);
1667         packet_put_cstring(authctxt->service);
1668         packet_put_cstring(authctxt->method->name);
1669         packet_put_cstring(pkalg);
1670         packet_put_string(blob, blen);
1671         packet_put_cstring(chost);
1672         packet_put_cstring(authctxt->local_user);
1673         packet_put_string(signature, slen);
1674         memset(signature, 's', slen);
1675         xfree(signature);
1676         xfree(chost);
1677         xfree(pkalg);
1678         xfree(blob);
1679
1680         packet_send();
1681         return 1;
1682 }
1683
1684 #ifdef JPAKE
1685 int
1686 userauth_jpake(Authctxt *authctxt)
1687 {
1688         struct jpake_ctx *pctx;
1689         u_char *x1_proof, *x2_proof;
1690         u_int x1_proof_len, x2_proof_len;
1691         static int attempt = 0; /* XXX share with userauth_password's? */
1692
1693         if (attempt++ >= options.number_of_password_prompts)
1694                 return 0;
1695         if (attempt != 1)
1696                 error("Permission denied, please try again.");
1697
1698         if (authctxt->methoddata != NULL)
1699                 fatal("%s: authctxt->methoddata already set (%p)",
1700                     __func__, authctxt->methoddata);
1701
1702         authctxt->methoddata = pctx = jpake_new();
1703
1704         /*
1705          * Send request immediately, to get the protocol going while
1706          * we do the initial computations.
1707          */
1708         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1709         packet_put_cstring(authctxt->server_user);
1710         packet_put_cstring(authctxt->service);
1711         packet_put_cstring(authctxt->method->name);
1712         packet_send();
1713         packet_write_wait();
1714
1715         jpake_step1(pctx->grp,
1716             &pctx->client_id, &pctx->client_id_len,
1717             &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2,
1718             &x1_proof, &x1_proof_len,
1719             &x2_proof, &x2_proof_len);
1720
1721         JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__));
1722
1723         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1);
1724         packet_put_string(pctx->client_id, pctx->client_id_len);
1725         packet_put_bignum2(pctx->g_x1);
1726         packet_put_bignum2(pctx->g_x2);
1727         packet_put_string(x1_proof, x1_proof_len);
1728         packet_put_string(x2_proof, x2_proof_len);
1729         packet_send();
1730
1731         bzero(x1_proof, x1_proof_len);
1732         bzero(x2_proof, x2_proof_len);
1733         xfree(x1_proof);
1734         xfree(x2_proof);
1735
1736         /* Expect step 1 packet from peer */
1737         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1,
1738             input_userauth_jpake_server_step1);
1739         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS,
1740             &input_userauth_success_unexpected);
1741
1742         return 1;
1743 }
1744
1745 void
1746 userauth_jpake_cleanup(Authctxt *authctxt)
1747 {
1748         debug3("%s: clean up", __func__);
1749         if (authctxt->methoddata != NULL) {
1750                 jpake_free(authctxt->methoddata);
1751                 authctxt->methoddata = NULL;
1752         }
1753         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
1754 }
1755 #endif /* JPAKE */
1756
1757 /* find auth method */
1758
1759 /*
1760  * given auth method name, if configurable options permit this method fill
1761  * in auth_ident field and return true, otherwise return false.
1762  */
1763 static int
1764 authmethod_is_enabled(Authmethod *method)
1765 {
1766         if (method == NULL)
1767                 return 0;
1768         /* return false if options indicate this method is disabled */
1769         if  (method->enabled == NULL || *method->enabled == 0)
1770                 return 0;
1771         /* return false if batch mode is enabled but method needs interactive mode */
1772         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1773                 return 0;
1774         return 1;
1775 }
1776
1777 static Authmethod *
1778 authmethod_lookup(const char *name)
1779 {
1780         Authmethod *method = NULL;
1781         if (name != NULL)
1782                 for (method = authmethods; method->name != NULL; method++)
1783                         if (strcmp(name, method->name) == 0)
1784                                 return method;
1785         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1786         return NULL;
1787 }
1788
1789 /* XXX internal state */
1790 static Authmethod *current = NULL;
1791 static char *supported = NULL;
1792 static char *preferred = NULL;
1793
1794 /*
1795  * Given the authentication method list sent by the server, return the
1796  * next method we should try.  If the server initially sends a nil list,
1797  * use a built-in default list.
1798  */
1799 static Authmethod *
1800 authmethod_get(char *authlist)
1801 {
1802         char *name = NULL;
1803         u_int next;
1804
1805         /* Use a suitable default if we're passed a nil list.  */
1806         if (authlist == NULL || strlen(authlist) == 0)
1807                 authlist = options.preferred_authentications;
1808
1809         if (supported == NULL || strcmp(authlist, supported) != 0) {
1810                 debug3("start over, passed a different list %s", authlist);
1811                 if (supported != NULL)
1812                         xfree(supported);
1813                 supported = xstrdup(authlist);
1814                 preferred = options.preferred_authentications;
1815                 debug3("preferred %s", preferred);
1816                 current = NULL;
1817         } else if (current != NULL && authmethod_is_enabled(current))
1818                 return current;
1819
1820         for (;;) {
1821                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1822                         debug("No more authentication methods to try.");
1823                         current = NULL;
1824                         return NULL;
1825                 }
1826                 preferred += next;
1827                 debug3("authmethod_lookup %s", name);
1828                 debug3("remaining preferred: %s", preferred);
1829                 if ((current = authmethod_lookup(name)) != NULL &&
1830                     authmethod_is_enabled(current)) {
1831                         debug3("authmethod_is_enabled %s", name);
1832                         debug("Next authentication method: %s", name);
1833                         return current;
1834                 }
1835         }
1836 }
1837
1838 static char *
1839 authmethods_get(void)
1840 {
1841         Authmethod *method = NULL;
1842         Buffer b;
1843         char *list;
1844
1845         buffer_init(&b);
1846         for (method = authmethods; method->name != NULL; method++) {
1847                 if (authmethod_is_enabled(method)) {
1848                         if (buffer_len(&b) > 0)
1849                                 buffer_append(&b, ",", 1);
1850                         buffer_append(&b, method->name, strlen(method->name));
1851                 }
1852         }
1853         buffer_append(&b, "\0", 1);
1854         list = xstrdup(buffer_ptr(&b));
1855         buffer_free(&b);
1856         return list;
1857 }
1858