crypto/openssh/sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.171 2009/03/05 07:18:19 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 extern Kex *xxx_kex;
  83
  84 /* tty_flag is set in ssh.c. use this in ssh_userauth2 */
  85 /* if it is set then prevent the switch to the null cipher */
  86
  87 extern int tty_flag;
  88
  89 /*
  90  * SSH2 key exchange
  91  */
  92
  93 u_char *session_id2 = NULL;
  94 u_int session_id2_len = 0;
  95
  96 char *xxx_host;
  97 struct sockaddr *xxx_hostaddr;
  98
  99 Kex *xxx_kex = NULL;
 100
 101 static int
 102 verify_host_key_callback(Key *hostkey)
 103 {
 104         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
 105                 fatal("Host key verification failed.");
 106         return 0;
 107 }
 108
 109 void
 110 ssh_kex2(char *host, struct sockaddr *hostaddr)
 111 {
 112         Kex *kex;
 113
 114         xxx_host = host;
 115         xxx_hostaddr = hostaddr;
 116
 117         if (options.ciphers == (char *)-1) {
 118                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 119                 options.ciphers = NULL;
 120         }
 121         if (options.ciphers != NULL) {
 122                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 123                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 124         }
 125         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 126             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 127         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 128             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 129         if (options.compression) {
 130                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 131                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 132         } else {
 133                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 134                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 135         }
 136         if (options.macs != NULL) {
 137                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 138                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 139         }
 140         if (options.hostkeyalgorithms != NULL)
 141                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 142                     options.hostkeyalgorithms;
 143
 144         if (options.rekey_limit)
 145                 packet_set_rekey_limit((u_int32_t)options.rekey_limit);
 146
 147         /* start key exchange */
 148         kex = kex_setup(myproposal);
 149         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 150         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 151         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 152         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 153         kex->client_version_string=client_version_string;
 154         kex->server_version_string=server_version_string;
 155         kex->verify_host_key=&verify_host_key_callback;
 156
 157         xxx_kex = kex;
 158
 159         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 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_failure(int, u_int32_t, void *);
 220 void    input_userauth_banner(int, u_int32_t, void *);
 221 void    input_userauth_error(int, u_int32_t, void *);
 222 void    input_userauth_info_req(int, u_int32_t, void *);
 223 void    input_userauth_pk_ok(int, u_int32_t, void *);
 224 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 225 void    input_userauth_jpake_server_step1(int, u_int32_t, void *);
 226 void    input_userauth_jpake_server_step2(int, u_int32_t, void *);
 227 void    input_userauth_jpake_server_confirm(int, u_int32_t, void *);
 228
 229 int     userauth_none(Authctxt *);
 230 int     userauth_pubkey(Authctxt *);
 231 int     userauth_passwd(Authctxt *);
 232 int     userauth_kbdint(Authctxt *);
 233 int     userauth_hostbased(Authctxt *);
 234 int     userauth_jpake(Authctxt *);
 235
 236 void    userauth_jpake_cleanup(Authctxt *);
 237
 238 #ifdef GSSAPI
 239 int     userauth_gssapi(Authctxt *authctxt);
 240 void    input_gssapi_response(int type, u_int32_t, void *);
 241 void    input_gssapi_token(int type, u_int32_t, void *);
 242 void    input_gssapi_hash(int type, u_int32_t, void *);
 243 void    input_gssapi_error(int, u_int32_t, void *);
 244 void    input_gssapi_errtok(int, u_int32_t, void *);
 245 #endif
 246
 247 void    userauth(Authctxt *, char *);
 248
 249 static int sign_and_send_pubkey(Authctxt *, Identity *);
 250 static void pubkey_prepare(Authctxt *);
 251 static void pubkey_cleanup(Authctxt *);
 252 static Key *load_identity_file(char *);
 253
 254 static Authmethod *authmethod_get(char *authlist);
 255 static Authmethod *authmethod_lookup(const char *name);
 256 static char *authmethods_get(void);
 257
 258 Authmethod authmethods[] = {
 259 #ifdef GSSAPI
 260         {"gssapi-with-mic",
 261                 userauth_gssapi,
 262                 NULL,
 263                 &options.gss_authentication,
 264                 NULL},
 265 #endif
 266         {"hostbased",
 267                 userauth_hostbased,
 268                 NULL,
 269                 &options.hostbased_authentication,
 270                 NULL},
 271         {"publickey",
 272                 userauth_pubkey,
 273                 NULL,
 274                 &options.pubkey_authentication,
 275                 NULL},
 276 #ifdef JPAKE
 277         {"jpake-01@openssh.com",
 278                 userauth_jpake,
 279                 userauth_jpake_cleanup,
 280                 &options.zero_knowledge_password_authentication,
 281                 &options.batch_mode},
 282 #endif
 283         {"keyboard-interactive",
 284                 userauth_kbdint,
 285                 NULL,
 286                 &options.kbd_interactive_authentication,
 287                 &options.batch_mode},
 288         {"password",
 289                 userauth_passwd,
 290                 NULL,
 291                 &options.password_authentication,
 292                 &options.batch_mode},
 293         {"none",
 294                 userauth_none,
 295                 NULL,
 296                 NULL,
 297                 NULL},
 298         {NULL, NULL, NULL, NULL, NULL}
 299 };
 300
 301 void
 302 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 303     Sensitive *sensitive)
 304 {
 305         Authctxt authctxt;
 306         int type;
 307
 308         if (options.challenge_response_authentication)
 309                 options.kbd_interactive_authentication = 1;
 310
 311         packet_start(SSH2_MSG_SERVICE_REQUEST);
 312         packet_put_cstring("ssh-userauth");
 313         packet_send();
 314         debug("SSH2_MSG_SERVICE_REQUEST sent");
 315         packet_write_wait();
 316         type = packet_read();
 317         if (type != SSH2_MSG_SERVICE_ACCEPT)
 318                 fatal("Server denied authentication request: %d", type);
 319         if (packet_remaining() > 0) {
 320                 char *reply = packet_get_string(NULL);
 321                 debug2("service_accept: %s", reply);
 322                 xfree(reply);
 323         } else {
 324                 debug2("buggy server: service_accept w/o service");
 325         }
 326         packet_check_eom();
 327         debug("SSH2_MSG_SERVICE_ACCEPT received");
 328
 329         if (options.preferred_authentications == NULL)
 330                 options.preferred_authentications = authmethods_get();
 331
 332         /* setup authentication context */
 333         memset(&authctxt, 0, sizeof(authctxt));
 334         pubkey_prepare(&authctxt);
 335         authctxt.server_user = server_user;
 336         authctxt.local_user = local_user;
 337         authctxt.host = host;
 338         authctxt.service = "ssh-connection";            /* service name */
 339         authctxt.success = 0;
 340         authctxt.method = authmethod_lookup("none");
 341         authctxt.authlist = NULL;
 342         authctxt.methoddata = NULL;
 343         authctxt.sensitive = sensitive;
 344         authctxt.info_req_seen = 0;
 345         if (authctxt.method == NULL)
 346                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 347
 348         /* initial userauth request */
 349         userauth_none(&authctxt);
 350
 351         dispatch_init(&input_userauth_error);
 352         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 353         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 354         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 355         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 356
 357         pubkey_cleanup(&authctxt);
 358         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 359
 360         /* if the user wants to use the none cipher do it */
 361         /* post authentication and only if the right conditions are met */
 362         /* both of the NONE commands must be true and there must be no */
 363         /* tty allocated */
 364         if ((options.none_switch == 1) && (options.none_enabled == 1))
 365         {
 366                 if (!tty_flag) /* no null on tty sessions */
 367                 {
 368                         debug("Requesting none rekeying...");
 369                         myproposal[PROPOSAL_ENC_ALGS_STOC] = "none";
 370                         myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none";
 371                         kex_prop2buf(&xxx_kex->my,myproposal);
 372                         packet_request_rekeying();
 373                         fprintf(stderr, "WARNING: ENABLED NONE CIPHER\n");
 374                 }
 375                 else
 376                 {
 377                         /* requested NONE cipher when in a tty */
 378                         debug("Cannot switch to NONE cipher with tty allocated");
 379                         fprintf(stderr, "NONE cipher switch disabled when a TTY is allocated\n");
 380                 }
 381         }
 382         debug("Authentication succeeded (%s).", authctxt.method->name);
 383 }
 384
 385 void
 386 userauth(Authctxt *authctxt, char *authlist)
 387 {
 388         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 389                 authctxt->method->cleanup(authctxt);
 390
 391         if (authctxt->methoddata) {
 392                 xfree(authctxt->methoddata);
 393                 authctxt->methoddata = NULL;
 394         }
 395         if (authlist == NULL) {
 396                 authlist = authctxt->authlist;
 397         } else {
 398                 if (authctxt->authlist)
 399                         xfree(authctxt->authlist);
 400                 authctxt->authlist = authlist;
 401         }
 402         for (;;) {
 403                 Authmethod *method = authmethod_get(authlist);
 404                 if (method == NULL)
 405                         fatal("Permission denied (%s).", authlist);
 406                 authctxt->method = method;
 407
 408                 /* reset the per method handler */
 409                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 410                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 411
 412                 /* and try new method */
 413                 if (method->userauth(authctxt) != 0) {
 414                         debug2("we sent a %s packet, wait for reply", method->name);
 415                         break;
 416                 } else {
 417                         debug2("we did not send a packet, disable method");
 418                         method->enabled = NULL;
 419                 }
 420         }
 421 }
 422
 423 /* ARGSUSED */
 424 void
 425 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 426 {
 427         fatal("input_userauth_error: bad message during authentication: "
 428             "type %d", type);
 429 }
 430
 431 /* ARGSUSED */
 432 void
 433 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 434 {
 435         char *msg, *raw, *lang;
 436         u_int len;
 437
 438         debug3("input_userauth_banner");
 439         raw = packet_get_string(&len);
 440         lang = packet_get_string(NULL);
 441         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
 442                 if (len > 65536)
 443                         len = 65536;
 444                 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
 445                 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL);
 446                 fprintf(stderr, "%s", msg);
 447                 xfree(msg);
 448         }
 449         xfree(raw);
 450         xfree(lang);
 451 }
 452
 453 /* ARGSUSED */
 454 void
 455 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 456 {
 457         Authctxt *authctxt = ctxt;
 458         if (authctxt == NULL)
 459                 fatal("input_userauth_success: no authentication context");
 460         if (authctxt->authlist) {
 461                 xfree(authctxt->authlist);
 462                 authctxt->authlist = NULL;
 463         }
 464         if (authctxt->methoddata) {
 465                 xfree(authctxt->methoddata);
 466                 authctxt->methoddata = NULL;
 467         }
 468         authctxt->success = 1;                  /* break out */
 469 }
 470
 471 /* ARGSUSED */
 472 void
 473 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 474 {
 475         Authctxt *authctxt = ctxt;
 476         char *authlist = NULL;
 477         int partial;
 478
 479         if (authctxt == NULL)
 480                 fatal("input_userauth_failure: no authentication context");
 481
 482         authlist = packet_get_string(NULL);
 483         partial = packet_get_char();
 484         packet_check_eom();
 485
 486         if (partial != 0)
 487                 logit("Authenticated with partial success.");
 488         debug("Authentications that can continue: %s", authlist);
 489
 490         userauth(authctxt, authlist);
 491 }
 492
 493 /* ARGSUSED */
 494 void
 495 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 496 {
 497         Authctxt *authctxt = ctxt;
 498         Key *key = NULL;
 499         Identity *id = NULL;
 500         Buffer b;
 501         int pktype, sent = 0;
 502         u_int alen, blen;
 503         char *pkalg, *fp;
 504         u_char *pkblob;
 505
 506         if (authctxt == NULL)
 507                 fatal("input_userauth_pk_ok: no authentication context");
 508         if (datafellows & SSH_BUG_PKOK) {
 509                 /* this is similar to SSH_BUG_PKAUTH */
 510                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 511                 pkblob = packet_get_string(&blen);
 512                 buffer_init(&b);
 513                 buffer_append(&b, pkblob, blen);
 514                 pkalg = buffer_get_string(&b, &alen);
 515                 buffer_free(&b);
 516         } else {
 517                 pkalg = packet_get_string(&alen);
 518                 pkblob = packet_get_string(&blen);
 519         }
 520         packet_check_eom();
 521
 522         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 523
 524         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 525                 debug("unknown pkalg %s", pkalg);
 526                 goto done;
 527         }
 528         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 529                 debug("no key from blob. pkalg %s", pkalg);
 530                 goto done;
 531         }
 532         if (key->type != pktype) {
 533                 error("input_userauth_pk_ok: type mismatch "
 534                     "for decoded key (received %d, expected %d)",
 535                     key->type, pktype);
 536                 goto done;
 537         }
 538         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 539         debug2("input_userauth_pk_ok: fp %s", fp);
 540         xfree(fp);
 541
 542         /*
 543          * search keys in the reverse order, because last candidate has been
 544          * moved to the end of the queue.  this also avoids confusion by
 545          * duplicate keys
 546          */
 547         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 548                 if (key_equal(key, id->key)) {
 549                         sent = sign_and_send_pubkey(authctxt, id);
 550                         break;
 551                 }
 552         }
 553 done:
 554         if (key != NULL)
 555                 key_free(key);
 556         xfree(pkalg);
 557         xfree(pkblob);
 558
 559         /* try another method if we did not send a packet */
 560         if (sent == 0)
 561                 userauth(authctxt, NULL);
 562 }
 563
 564 #ifdef GSSAPI
 565 int
 566 userauth_gssapi(Authctxt *authctxt)
 567 {
 568         Gssctxt *gssctxt = NULL;
 569         static gss_OID_set gss_supported = NULL;
 570         static u_int mech = 0;
 571         OM_uint32 min;
 572         int ok = 0;
 573
 574         /* Try one GSSAPI method at a time, rather than sending them all at
 575          * once. */
 576
 577         if (gss_supported == NULL)
 578                 gss_indicate_mechs(&min, &gss_supported);
 579
 580         /* Check to see if the mechanism is usable before we offer it */
 581         while (mech < gss_supported->count && !ok) {
 582                 /* My DER encoding requires length<128 */
 583                 if (gss_supported->elements[mech].length < 128 &&
 584                     ssh_gssapi_check_mechanism(&gssctxt,
 585                     &gss_supported->elements[mech], authctxt->host)) {
 586                         ok = 1; /* Mechanism works */
 587                 } else {
 588                         mech++;
 589                 }
 590         }
 591
 592         if (!ok)
 593                 return 0;
 594
 595         authctxt->methoddata=(void *)gssctxt;
 596
 597         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 598         packet_put_cstring(authctxt->server_user);
 599         packet_put_cstring(authctxt->service);
 600         packet_put_cstring(authctxt->method->name);
 601
 602         packet_put_int(1);
 603
 604         packet_put_int((gss_supported->elements[mech].length) + 2);
 605         packet_put_char(SSH_GSS_OIDTYPE);
 606         packet_put_char(gss_supported->elements[mech].length);
 607         packet_put_raw(gss_supported->elements[mech].elements,
 608             gss_supported->elements[mech].length);
 609
 610         packet_send();
 611
 612         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 613         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 614         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 615         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 616
 617         mech++; /* Move along to next candidate */
 618
 619         return 1;
 620 }
 621
 622 static OM_uint32
 623 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 624 {
 625         Authctxt *authctxt = ctxt;
 626         Gssctxt *gssctxt = authctxt->methoddata;
 627         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 628         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 629         gss_buffer_desc gssbuf;
 630         OM_uint32 status, ms, flags;
 631         Buffer b;
 632
 633         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 634             recv_tok, &send_tok, &flags);
 635
 636         if (send_tok.length > 0) {
 637                 if (GSS_ERROR(status))
 638                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 639                 else
 640                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 641
 642                 packet_put_string(send_tok.value, send_tok.length);
 643                 packet_send();
 644                 gss_release_buffer(&ms, &send_tok);
 645         }
 646
 647         if (status == GSS_S_COMPLETE) {
 648                 /* send either complete or MIC, depending on mechanism */
 649                 if (!(flags & GSS_C_INTEG_FLAG)) {
 650                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 651                         packet_send();
 652                 } else {
 653                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 654                             authctxt->service, "gssapi-with-mic");
 655
 656                         gssbuf.value = buffer_ptr(&b);
 657                         gssbuf.length = buffer_len(&b);
 658
 659                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 660
 661                         if (!GSS_ERROR(status)) {
 662                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 663                                 packet_put_string(mic.value, mic.length);
 664
 665                                 packet_send();
 666                         }
 667
 668                         buffer_free(&b);
 669                         gss_release_buffer(&ms, &mic);
 670                 }
 671         }
 672
 673         return status;
 674 }
 675
 676 /* ARGSUSED */
 677 void
 678 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 679 {
 680         Authctxt *authctxt = ctxt;
 681         Gssctxt *gssctxt;
 682         int oidlen;
 683         char *oidv;
 684
 685         if (authctxt == NULL)
 686                 fatal("input_gssapi_response: no authentication context");
 687         gssctxt = authctxt->methoddata;
 688
 689         /* Setup our OID */
 690         oidv = packet_get_string(&oidlen);
 691
 692         if (oidlen <= 2 ||
 693             oidv[0] != SSH_GSS_OIDTYPE ||
 694             oidv[1] != oidlen - 2) {
 695                 xfree(oidv);
 696                 debug("Badly encoded mechanism OID received");
 697                 userauth(authctxt, NULL);
 698                 return;
 699         }
 700
 701         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 702                 fatal("Server returned different OID than expected");
 703
 704         packet_check_eom();
 705
 706         xfree(oidv);
 707
 708         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 709                 /* Start again with next method on list */
 710                 debug("Trying to start again");
 711                 userauth(authctxt, NULL);
 712                 return;
 713         }
 714 }
 715
 716 /* ARGSUSED */
 717 void
 718 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 719 {
 720         Authctxt *authctxt = ctxt;
 721         gss_buffer_desc recv_tok;
 722         OM_uint32 status;
 723         u_int slen;
 724
 725         if (authctxt == NULL)
 726                 fatal("input_gssapi_response: no authentication context");
 727
 728         recv_tok.value = packet_get_string(&slen);
 729         recv_tok.length = slen; /* safe typecast */
 730
 731         packet_check_eom();
 732
 733         status = process_gssapi_token(ctxt, &recv_tok);
 734
 735         xfree(recv_tok.value);
 736
 737         if (GSS_ERROR(status)) {
 738                 /* Start again with the next method in the list */
 739                 userauth(authctxt, NULL);
 740                 return;
 741         }
 742 }
 743
 744 /* ARGSUSED */
 745 void
 746 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 747 {
 748         Authctxt *authctxt = ctxt;
 749         Gssctxt *gssctxt;
 750         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 751         gss_buffer_desc recv_tok;
 752         OM_uint32 status, ms;
 753         u_int len;
 754
 755         if (authctxt == NULL)
 756                 fatal("input_gssapi_response: no authentication context");
 757         gssctxt = authctxt->methoddata;
 758
 759         recv_tok.value = packet_get_string(&len);
 760         recv_tok.length = len;
 761
 762         packet_check_eom();
 763
 764         /* Stick it into GSSAPI and see what it says */
 765         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 766             &recv_tok, &send_tok, NULL);
 767
 768         xfree(recv_tok.value);
 769         gss_release_buffer(&ms, &send_tok);
 770
 771         /* Server will be returning a failed packet after this one */
 772 }
 773
 774 /* ARGSUSED */
 775 void
 776 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 777 {
 778         OM_uint32 maj, min;
 779         char *msg;
 780         char *lang;
 781
 782         maj=packet_get_int();
 783         min=packet_get_int();
 784         msg=packet_get_string(NULL);
 785         lang=packet_get_string(NULL);
 786
 787         packet_check_eom();
 788
 789         debug("Server GSSAPI Error:\n%s", msg);
 790         xfree(msg);
 791         xfree(lang);
 792 }
 793 #endif /* GSSAPI */
 794
 795 int
 796 userauth_none(Authctxt *authctxt)
 797 {
 798         /* initial userauth request */
 799         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 800         packet_put_cstring(authctxt->server_user);
 801         packet_put_cstring(authctxt->service);
 802         packet_put_cstring(authctxt->method->name);
 803         packet_send();
 804         return 1;
 805 }
 806
 807 int
 808 userauth_passwd(Authctxt *authctxt)
 809 {
 810         static int attempt = 0;
 811         char prompt[150];
 812         char *password;
 813
 814         if (attempt++ >= options.number_of_password_prompts)
 815                 return 0;
 816
 817         if (attempt != 1)
 818                 error("Permission denied, please try again.");
 819
 820         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 821             authctxt->server_user, authctxt->host);
 822         password = read_passphrase(prompt, 0);
 823         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 824         packet_put_cstring(authctxt->server_user);
 825         packet_put_cstring(authctxt->service);
 826         packet_put_cstring(authctxt->method->name);
 827         packet_put_char(0);
 828         packet_put_cstring(password);
 829         memset(password, 0, strlen(password));
 830         xfree(password);
 831         packet_add_padding(64);
 832         packet_send();
 833
 834         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 835             &input_userauth_passwd_changereq);
 836
 837         return 1;
 838 }
 839
 840 /*
 841  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 842  */
 843 /* ARGSUSED */
 844 void
 845 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 846 {
 847         Authctxt *authctxt = ctxt;
 848         char *info, *lang, *password = NULL, *retype = NULL;
 849         char prompt[150];
 850
 851         debug2("input_userauth_passwd_changereq");
 852
 853         if (authctxt == NULL)
 854                 fatal("input_userauth_passwd_changereq: "
 855                     "no authentication context");
 856
 857         info = packet_get_string(NULL);
 858         lang = packet_get_string(NULL);
 859         if (strlen(info) > 0)
 860                 logit("%s", info);
 861         xfree(info);
 862         xfree(lang);
 863         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 864         packet_put_cstring(authctxt->server_user);
 865         packet_put_cstring(authctxt->service);
 866         packet_put_cstring(authctxt->method->name);
 867         packet_put_char(1);                     /* additional info */
 868         snprintf(prompt, sizeof(prompt),
 869             "Enter %.30s@%.128s's old password: ",
 870             authctxt->server_user, authctxt->host);
 871         password = read_passphrase(prompt, 0);
 872         packet_put_cstring(password);
 873         memset(password, 0, strlen(password));
 874         xfree(password);
 875         password = NULL;
 876         while (password == NULL) {
 877                 snprintf(prompt, sizeof(prompt),
 878                     "Enter %.30s@%.128s's new password: ",
 879                     authctxt->server_user, authctxt->host);
 880                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 881                 if (password == NULL) {
 882                         /* bail out */
 883                         return;
 884                 }
 885                 snprintf(prompt, sizeof(prompt),
 886                     "Retype %.30s@%.128s's new password: ",
 887                     authctxt->server_user, authctxt->host);
 888                 retype = read_passphrase(prompt, 0);
 889                 if (strcmp(password, retype) != 0) {
 890                         memset(password, 0, strlen(password));
 891                         xfree(password);
 892                         logit("Mismatch; try again, EOF to quit.");
 893                         password = NULL;
 894                 }
 895                 memset(retype, 0, strlen(retype));
 896                 xfree(retype);
 897         }
 898         packet_put_cstring(password);
 899         memset(password, 0, strlen(password));
 900         xfree(password);
 901         packet_add_padding(64);
 902         packet_send();
 903
 904         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 905             &input_userauth_passwd_changereq);
 906 }
 907
 908 #ifdef JPAKE
 909 static char *
 910 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt)
 911 {
 912         /* OpenBSD crypt(3) handles all of these */
 913         if (strcmp(crypt_scheme, "crypt") == 0 ||
 914             strcmp(crypt_scheme, "bcrypt") == 0 ||
 915             strcmp(crypt_scheme, "md5crypt") == 0 ||
 916             strcmp(crypt_scheme, "crypt-extended") == 0)
 917                 return xstrdup(crypt(password, salt));
 918         error("%s: unsupported password encryption scheme \"%.100s\"",
 919             __func__, crypt_scheme);
 920         return NULL;
 921 }
 922
 923 static BIGNUM *
 924 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme,
 925     const char *salt)
 926 {
 927         char prompt[256], *password, *crypted;
 928         u_char *secret;
 929         u_int secret_len;
 930         BIGNUM *ret;
 931
 932         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ",
 933             authctxt->server_user, authctxt->host);
 934         password = read_passphrase(prompt, 0);
 935
 936         if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) {
 937                 logit("Disabling %s authentication", authctxt->method->name);
 938                 authctxt->method->enabled = NULL;
 939                 /* Continue with an empty password to fail gracefully */
 940                 crypted = xstrdup("");
 941         }
 942
 943 #ifdef JPAKE_DEBUG
 944         debug3("%s: salt = %s", __func__, salt);
 945         debug3("%s: scheme = %s", __func__, crypt_scheme);
 946         debug3("%s: crypted = %s", __func__, crypted);
 947 #endif
 948
 949         if (hash_buffer(crypted, strlen(crypted), EVP_sha256(),
 950             &secret, &secret_len) != 0)
 951                 fatal("%s: hash_buffer", __func__);
 952
 953         bzero(password, strlen(password));
 954         bzero(crypted, strlen(crypted));
 955         xfree(password);
 956         xfree(crypted);
 957
 958         if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL)
 959                 fatal("%s: BN_bin2bn (secret)", __func__);
 960         bzero(secret, secret_len);
 961         xfree(secret);
 962
 963         return ret;
 964 }
 965
 966 /* ARGSUSED */
 967 void
 968 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt)
 969 {
 970         Authctxt *authctxt = ctxt;
 971         struct jpake_ctx *pctx = authctxt->methoddata;
 972         u_char *x3_proof, *x4_proof, *x2_s_proof;
 973         u_int x3_proof_len, x4_proof_len, x2_s_proof_len;
 974         char *crypt_scheme, *salt;
 975
 976         /* Disable this message */
 977         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL);
 978
 979         if ((pctx->g_x3 = BN_new()) == NULL ||
 980             (pctx->g_x4 = BN_new()) == NULL)
 981                 fatal("%s: BN_new", __func__);
 982
 983         /* Fetch step 1 values */
 984         crypt_scheme = packet_get_string(NULL);
 985         salt = packet_get_string(NULL);
 986         pctx->server_id = packet_get_string(&pctx->server_id_len);
 987         packet_get_bignum2(pctx->g_x3);
 988         packet_get_bignum2(pctx->g_x4);
 989         x3_proof = packet_get_string(&x3_proof_len);
 990         x4_proof = packet_get_string(&x4_proof_len);
 991         packet_check_eom();
 992
 993         JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__));
 994
 995         /* Obtain password and derive secret */
 996         pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt);
 997         bzero(crypt_scheme, strlen(crypt_scheme));
 998         bzero(salt, strlen(salt));
 999         xfree(crypt_scheme);
1000         xfree(salt);
1001         JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__));
1002
1003         /* Calculate step 2 values */
1004         jpake_step2(pctx->grp, pctx->s, pctx->g_x1,
1005             pctx->g_x3, pctx->g_x4, pctx->x2,
1006             pctx->server_id, pctx->server_id_len,
1007             pctx->client_id, pctx->client_id_len,
1008             x3_proof, x3_proof_len,
1009             x4_proof, x4_proof_len,
1010             &pctx->a,
1011             &x2_s_proof, &x2_s_proof_len);
1012
1013         bzero(x3_proof, x3_proof_len);
1014         bzero(x4_proof, x4_proof_len);
1015         xfree(x3_proof);
1016         xfree(x4_proof);
1017
1018         JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__));
1019
1020         /* Send values for step 2 */
1021         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2);
1022         packet_put_bignum2(pctx->a);
1023         packet_put_string(x2_s_proof, x2_s_proof_len);
1024         packet_send();
1025
1026         bzero(x2_s_proof, x2_s_proof_len);
1027         xfree(x2_s_proof);
1028
1029         /* Expect step 2 packet from peer */
1030         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2,
1031             input_userauth_jpake_server_step2);
1032 }
1033
1034 /* ARGSUSED */
1035 void
1036 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt)
1037 {
1038         Authctxt *authctxt = ctxt;
1039         struct jpake_ctx *pctx = authctxt->methoddata;
1040         u_char *x4_s_proof;
1041         u_int x4_s_proof_len;
1042
1043         /* Disable this message */
1044         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL);
1045
1046         if ((pctx->b = BN_new()) == NULL)
1047                 fatal("%s: BN_new", __func__);
1048
1049         /* Fetch step 2 values */
1050         packet_get_bignum2(pctx->b);
1051         x4_s_proof = packet_get_string(&x4_s_proof_len);
1052         packet_check_eom();
1053
1054         JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__));
1055
1056         /* Derive shared key and calculate confirmation hash */
1057         jpake_key_confirm(pctx->grp, pctx->s, pctx->b,
1058             pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4,
1059             pctx->client_id, pctx->client_id_len,
1060             pctx->server_id, pctx->server_id_len,
1061             session_id2, session_id2_len,
1062             x4_s_proof, x4_s_proof_len,
1063             &pctx->k,
1064             &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len);
1065
1066         bzero(x4_s_proof, x4_s_proof_len);
1067         xfree(x4_s_proof);
1068
1069         JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__));
1070
1071         /* Send key confirmation proof */
1072         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM);
1073         packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len);
1074         packet_send();
1075
1076         /* Expect confirmation from peer */
1077         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM,
1078             input_userauth_jpake_server_confirm);
1079 }
1080
1081 /* ARGSUSED */
1082 void
1083 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt)
1084 {
1085         Authctxt *authctxt = ctxt;
1086         struct jpake_ctx *pctx = authctxt->methoddata;
1087
1088         /* Disable this message */
1089         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL);
1090
1091         pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len);
1092         packet_check_eom();
1093
1094         JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__));
1095
1096         /* Verify expected confirmation hash */
1097         if (jpake_check_confirm(pctx->k,
1098             pctx->server_id, pctx->server_id_len,
1099             session_id2, session_id2_len,
1100             pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1)
1101                 debug("%s: %s success", __func__, authctxt->method->name);
1102         else {
1103                 debug("%s: confirmation mismatch", __func__);
1104                 /* XXX stash this so if auth succeeds then we can warn/kill */
1105         }
1106
1107         userauth_jpake_cleanup(authctxt);
1108 }
1109 #endif /* JPAKE */
1110
1111 static int
1112 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
1113     u_char *data, u_int datalen)
1114 {
1115         Key *prv;
1116         int ret;
1117
1118         /* the agent supports this key */
1119         if (id->ac)
1120                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1121                     data, datalen));
1122         /*
1123          * we have already loaded the private key or
1124          * the private key is stored in external hardware
1125          */
1126         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1127                 return (key_sign(id->key, sigp, lenp, data, datalen));
1128         /* load the private key from the file */
1129         if ((prv = load_identity_file(id->filename)) == NULL)
1130                 return (-1);
1131         ret = key_sign(prv, sigp, lenp, data, datalen);
1132         key_free(prv);
1133         return (ret);
1134 }
1135
1136 static int
1137 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1138 {
1139         Buffer b;
1140         u_char *blob, *signature;
1141         u_int bloblen, slen;
1142         u_int skip = 0;
1143         int ret = -1;
1144         int have_sig = 1;
1145
1146         debug3("sign_and_send_pubkey");
1147
1148         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1149                 /* we cannot handle this key */
1150                 debug3("sign_and_send_pubkey: cannot handle key");
1151                 return 0;
1152         }
1153         /* data to be signed */
1154         buffer_init(&b);
1155         if (datafellows & SSH_OLD_SESSIONID) {
1156                 buffer_append(&b, session_id2, session_id2_len);
1157                 skip = session_id2_len;
1158         } else {
1159                 buffer_put_string(&b, session_id2, session_id2_len);
1160                 skip = buffer_len(&b);
1161         }
1162         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1163         buffer_put_cstring(&b, authctxt->server_user);
1164         buffer_put_cstring(&b,
1165             datafellows & SSH_BUG_PKSERVICE ?
1166             "ssh-userauth" :
1167             authctxt->service);
1168         if (datafellows & SSH_BUG_PKAUTH) {
1169                 buffer_put_char(&b, have_sig);
1170         } else {
1171                 buffer_put_cstring(&b, authctxt->method->name);
1172                 buffer_put_char(&b, have_sig);
1173                 buffer_put_cstring(&b, key_ssh_name(id->key));
1174         }
1175         buffer_put_string(&b, blob, bloblen);
1176
1177         /* generate signature */
1178         ret = identity_sign(id, &signature, &slen,
1179             buffer_ptr(&b), buffer_len(&b));
1180         if (ret == -1) {
1181                 xfree(blob);
1182                 buffer_free(&b);
1183                 return 0;
1184         }
1185 #ifdef DEBUG_PK
1186         buffer_dump(&b);
1187 #endif
1188         if (datafellows & SSH_BUG_PKSERVICE) {
1189                 buffer_clear(&b);
1190                 buffer_append(&b, session_id2, session_id2_len);
1191                 skip = session_id2_len;
1192                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1193                 buffer_put_cstring(&b, authctxt->server_user);
1194                 buffer_put_cstring(&b, authctxt->service);
1195                 buffer_put_cstring(&b, authctxt->method->name);
1196                 buffer_put_char(&b, have_sig);
1197                 if (!(datafellows & SSH_BUG_PKAUTH))
1198                         buffer_put_cstring(&b, key_ssh_name(id->key));
1199                 buffer_put_string(&b, blob, bloblen);
1200         }
1201         xfree(blob);
1202
1203         /* append signature */
1204         buffer_put_string(&b, signature, slen);
1205         xfree(signature);
1206
1207         /* skip session id and packet type */
1208         if (buffer_len(&b) < skip + 1)
1209                 fatal("userauth_pubkey: internal error");
1210         buffer_consume(&b, skip + 1);
1211
1212         /* put remaining data from buffer into packet */
1213         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1214         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1215         buffer_free(&b);
1216         packet_send();
1217
1218         return 1;
1219 }
1220
1221 static int
1222 send_pubkey_test(Authctxt *authctxt, Identity *id)
1223 {
1224         u_char *blob;
1225         u_int bloblen, have_sig = 0;
1226
1227         debug3("send_pubkey_test");
1228
1229         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1230                 /* we cannot handle this key */
1231                 debug3("send_pubkey_test: cannot handle key");
1232                 return 0;
1233         }
1234         /* register callback for USERAUTH_PK_OK message */
1235         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1236
1237         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1238         packet_put_cstring(authctxt->server_user);
1239         packet_put_cstring(authctxt->service);
1240         packet_put_cstring(authctxt->method->name);
1241         packet_put_char(have_sig);
1242         if (!(datafellows & SSH_BUG_PKAUTH))
1243                 packet_put_cstring(key_ssh_name(id->key));
1244         packet_put_string(blob, bloblen);
1245         xfree(blob);
1246         packet_send();
1247         return 1;
1248 }
1249
1250 static Key *
1251 load_identity_file(char *filename)
1252 {
1253         Key *private;
1254         char prompt[300], *passphrase;
1255         int perm_ok, quit, i;
1256         struct stat st;
1257
1258         if (stat(filename, &st) < 0) {
1259                 debug3("no such identity: %s", filename);
1260                 return NULL;
1261         }
1262         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1263         if (!perm_ok)
1264                 return NULL;
1265         if (private == NULL) {
1266                 if (options.batch_mode)
1267                         return NULL;
1268                 snprintf(prompt, sizeof prompt,
1269                     "Enter passphrase for key '%.100s': ", filename);
1270                 for (i = 0; i < options.number_of_password_prompts; i++) {
1271                         passphrase = read_passphrase(prompt, 0);
1272                         if (strcmp(passphrase, "") != 0) {
1273                                 private = key_load_private_type(KEY_UNSPEC,
1274                                     filename, passphrase, NULL, NULL);
1275                                 quit = 0;
1276                         } else {
1277                                 debug2("no passphrase given, try next key");
1278                                 quit = 1;
1279                         }
1280                         memset(passphrase, 0, strlen(passphrase));
1281                         xfree(passphrase);
1282                         if (private != NULL || quit)
1283                                 break;
1284                         debug2("bad passphrase given, try again...");
1285                 }
1286         }
1287         return private;
1288 }
1289
1290 /*
1291  * try keys in the following order:
1292  *      1. agent keys that are found in the config file
1293  *      2. other agent keys
1294  *      3. keys that are only listed in the config file
1295  */
1296 static void
1297 pubkey_prepare(Authctxt *authctxt)
1298 {
1299         Identity *id;
1300         Idlist agent, files, *preferred;
1301         Key *key;
1302         AuthenticationConnection *ac;
1303         char *comment;
1304         int i, found;
1305
1306         TAILQ_INIT(&agent);     /* keys from the agent */
1307         TAILQ_INIT(&files);     /* keys from the config file */
1308         preferred = &authctxt->keys;
1309         TAILQ_INIT(preferred);  /* preferred order of keys */
1310
1311         /* list of keys stored in the filesystem */
1312         for (i = 0; i < options.num_identity_files; i++) {
1313                 key = options.identity_keys[i];
1314                 if (key && key->type == KEY_RSA1)
1315                         continue;
1316                 options.identity_keys[i] = NULL;
1317                 id = xcalloc(1, sizeof(*id));
1318                 id->key = key;
1319                 id->filename = xstrdup(options.identity_files[i]);
1320                 TAILQ_INSERT_TAIL(&files, id, next);
1321         }
1322         /* list of keys supported by the agent */
1323         if ((ac = ssh_get_authentication_connection())) {
1324                 for (key = ssh_get_first_identity(ac, &comment, 2);
1325                     key != NULL;
1326                     key = ssh_get_next_identity(ac, &comment, 2)) {
1327                         found = 0;
1328                         TAILQ_FOREACH(id, &files, next) {
1329                                 /* agent keys from the config file are preferred */
1330                                 if (key_equal(key, id->key)) {
1331                                         key_free(key);
1332                                         xfree(comment);
1333                                         TAILQ_REMOVE(&files, id, next);
1334                                         TAILQ_INSERT_TAIL(preferred, id, next);
1335                                         id->ac = ac;
1336                                         found = 1;
1337                                         break;
1338                                 }
1339                         }
1340                         if (!found && !options.identities_only) {
1341                                 id = xcalloc(1, sizeof(*id));
1342                                 id->key = key;
1343                                 id->filename = comment;
1344                                 id->ac = ac;
1345                                 TAILQ_INSERT_TAIL(&agent, id, next);
1346                         }
1347                 }
1348                 /* append remaining agent keys */
1349                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1350                         TAILQ_REMOVE(&agent, id, next);
1351                         TAILQ_INSERT_TAIL(preferred, id, next);
1352                 }
1353                 authctxt->agent = ac;
1354         }
1355         /* append remaining keys from the config file */
1356         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1357                 TAILQ_REMOVE(&files, id, next);
1358                 TAILQ_INSERT_TAIL(preferred, id, next);
1359         }
1360         TAILQ_FOREACH(id, preferred, next) {
1361                 debug2("key: %s (%p)", id->filename, id->key);
1362         }
1363 }
1364
1365 static void
1366 pubkey_cleanup(Authctxt *authctxt)
1367 {
1368         Identity *id;
1369
1370         if (authctxt->agent != NULL)
1371                 ssh_close_authentication_connection(authctxt->agent);
1372         for (id = TAILQ_FIRST(&authctxt->keys); id;
1373             id = TAILQ_FIRST(&authctxt->keys)) {
1374                 TAILQ_REMOVE(&authctxt->keys, id, next);
1375                 if (id->key)
1376                         key_free(id->key);
1377                 if (id->filename)
1378                         xfree(id->filename);
1379                 xfree(id);
1380         }
1381 }
1382
1383 int
1384 userauth_pubkey(Authctxt *authctxt)
1385 {
1386         Identity *id;
1387         int sent = 0;
1388
1389         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1390                 if (id->tried++)
1391                         return (0);
1392                 /* move key to the end of the queue */
1393                 TAILQ_REMOVE(&authctxt->keys, id, next);
1394                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1395                 /*
1396                  * send a test message if we have the public key. for
1397                  * encrypted keys we cannot do this and have to load the
1398                  * private key instead
1399                  */
1400                 if (id->key && id->key->type != KEY_RSA1) {
1401                         debug("Offering public key: %s", id->filename);
1402                         sent = send_pubkey_test(authctxt, id);
1403                 } else if (id->key == NULL) {
1404                         debug("Trying private key: %s", id->filename);
1405                         id->key = load_identity_file(id->filename);
1406                         if (id->key != NULL) {
1407                                 id->isprivate = 1;
1408                                 sent = sign_and_send_pubkey(authctxt, id);
1409                                 key_free(id->key);
1410                                 id->key = NULL;
1411                         }
1412                 }
1413                 if (sent)
1414                         return (sent);
1415         }
1416         return (0);
1417 }
1418
1419 /*
1420  * Send userauth request message specifying keyboard-interactive method.
1421  */
1422 int
1423 userauth_kbdint(Authctxt *authctxt)
1424 {
1425         static int attempt = 0;
1426
1427         if (attempt++ >= options.number_of_password_prompts)
1428                 return 0;
1429         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1430         if (attempt > 1 && !authctxt->info_req_seen) {
1431                 debug3("userauth_kbdint: disable: no info_req_seen");
1432                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1433                 return 0;
1434         }
1435
1436         debug2("userauth_kbdint");
1437         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1438         packet_put_cstring(authctxt->server_user);
1439         packet_put_cstring(authctxt->service);
1440         packet_put_cstring(authctxt->method->name);
1441         packet_put_cstring("");                                 /* lang */
1442         packet_put_cstring(options.kbd_interactive_devices ?
1443             options.kbd_interactive_devices : "");
1444         packet_send();
1445
1446         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1447         return 1;
1448 }
1449
1450 /*
1451  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1452  */
1453 void
1454 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1455 {
1456         Authctxt *authctxt = ctxt;
1457         char *name, *inst, *lang, *prompt, *response;
1458         u_int num_prompts, i;
1459         int echo = 0;
1460
1461         debug2("input_userauth_info_req");
1462
1463         if (authctxt == NULL)
1464                 fatal("input_userauth_info_req: no authentication context");
1465
1466         authctxt->info_req_seen = 1;
1467
1468         name = packet_get_string(NULL);
1469         inst = packet_get_string(NULL);
1470         lang = packet_get_string(NULL);
1471         if (strlen(name) > 0)
1472                 logit("%s", name);
1473         if (strlen(inst) > 0)
1474                 logit("%s", inst);
1475         xfree(name);
1476         xfree(inst);
1477         xfree(lang);
1478
1479         num_prompts = packet_get_int();
1480         /*
1481          * Begin to build info response packet based on prompts requested.
1482          * We commit to providing the correct number of responses, so if
1483          * further on we run into a problem that prevents this, we have to
1484          * be sure and clean this up and send a correct error response.
1485          */
1486         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1487         packet_put_int(num_prompts);
1488
1489         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1490         for (i = 0; i < num_prompts; i++) {
1491                 prompt = packet_get_string(NULL);
1492                 echo = packet_get_char();
1493
1494                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1495
1496                 packet_put_cstring(response);
1497                 memset(response, 0, strlen(response));
1498                 xfree(response);
1499                 xfree(prompt);
1500         }
1501         packet_check_eom(); /* done with parsing incoming message. */
1502
1503         packet_add_padding(64);
1504         packet_send();
1505 }
1506
1507 static int
1508 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1509     u_char *data, u_int datalen)
1510 {
1511         Buffer b;
1512         struct stat st;
1513         pid_t pid;
1514         int to[2], from[2], status, version = 2;
1515
1516         debug2("ssh_keysign called");
1517
1518         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1519                 error("ssh_keysign: no installed: %s", strerror(errno));
1520                 return -1;
1521         }
1522         if (fflush(stdout) != 0)
1523                 error("ssh_keysign: fflush: %s", strerror(errno));
1524         if (pipe(to) < 0) {
1525                 error("ssh_keysign: pipe: %s", strerror(errno));
1526                 return -1;
1527         }
1528         if (pipe(from) < 0) {
1529                 error("ssh_keysign: pipe: %s", strerror(errno));
1530                 return -1;
1531         }
1532         if ((pid = fork()) < 0) {
1533                 error("ssh_keysign: fork: %s", strerror(errno));
1534                 return -1;
1535         }
1536         if (pid == 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, len, 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         len = strlen(p) + 2;
1630         xasprintf(&chost, "%s.", p);
1631         debug2("userauth_hostbased: chost %s", chost);
1632         xfree(p);
1633
1634         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1635             authctxt->service;
1636         pkalg = xstrdup(key_ssh_name(private));
1637         buffer_init(&b);
1638         /* construct data */
1639         buffer_put_string(&b, session_id2, session_id2_len);
1640         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1641         buffer_put_cstring(&b, authctxt->server_user);
1642         buffer_put_cstring(&b, service);
1643         buffer_put_cstring(&b, authctxt->method->name);
1644         buffer_put_cstring(&b, pkalg);
1645         buffer_put_string(&b, blob, blen);
1646         buffer_put_cstring(&b, chost);
1647         buffer_put_cstring(&b, authctxt->local_user);
1648 #ifdef DEBUG_PK
1649         buffer_dump(&b);
1650 #endif
1651         if (sensitive->external_keysign)
1652                 ok = ssh_keysign(private, &signature, &slen,
1653                     buffer_ptr(&b), buffer_len(&b));
1654         else
1655                 ok = key_sign(private, &signature, &slen,
1656                     buffer_ptr(&b), buffer_len(&b));
1657         key_free(private);
1658         buffer_free(&b);
1659         if (ok != 0) {
1660                 error("key_sign failed");
1661                 xfree(chost);
1662                 xfree(pkalg);
1663                 xfree(blob);
1664                 return 0;
1665         }
1666         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1667         packet_put_cstring(authctxt->server_user);
1668         packet_put_cstring(authctxt->service);
1669         packet_put_cstring(authctxt->method->name);
1670         packet_put_cstring(pkalg);
1671         packet_put_string(blob, blen);
1672         packet_put_cstring(chost);
1673         packet_put_cstring(authctxt->local_user);
1674         packet_put_string(signature, slen);
1675         memset(signature, 's', slen);
1676         xfree(signature);
1677         xfree(chost);
1678         xfree(pkalg);
1679         xfree(blob);
1680
1681         packet_send();
1682         return 1;
1683 }
1684
1685 #ifdef JPAKE
1686 int
1687 userauth_jpake(Authctxt *authctxt)
1688 {
1689         struct jpake_ctx *pctx;
1690         u_char *x1_proof, *x2_proof;
1691         u_int x1_proof_len, x2_proof_len;
1692         static int attempt = 0; /* XXX share with userauth_password's? */
1693
1694         if (attempt++ >= options.number_of_password_prompts)
1695                 return 0;
1696         if (attempt != 1)
1697                 error("Permission denied, please try again.");
1698
1699         if (authctxt->methoddata != NULL)
1700                 fatal("%s: authctxt->methoddata already set (%p)",
1701                     __func__, authctxt->methoddata);
1702
1703         authctxt->methoddata = pctx = jpake_new();
1704
1705         /*
1706          * Send request immediately, to get the protocol going while
1707          * we do the initial computations.
1708          */
1709         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1710         packet_put_cstring(authctxt->server_user);
1711         packet_put_cstring(authctxt->service);
1712         packet_put_cstring(authctxt->method->name);
1713         packet_send();
1714         packet_write_wait();
1715
1716         jpake_step1(pctx->grp,
1717             &pctx->client_id, &pctx->client_id_len,
1718             &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2,
1719             &x1_proof, &x1_proof_len,
1720             &x2_proof, &x2_proof_len);
1721
1722         JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__));
1723
1724         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1);
1725         packet_put_string(pctx->client_id, pctx->client_id_len);
1726         packet_put_bignum2(pctx->g_x1);
1727         packet_put_bignum2(pctx->g_x2);
1728         packet_put_string(x1_proof, x1_proof_len);
1729         packet_put_string(x2_proof, x2_proof_len);
1730         packet_send();
1731
1732         bzero(x1_proof, x1_proof_len);
1733         bzero(x2_proof, x2_proof_len);
1734         xfree(x1_proof);
1735         xfree(x2_proof);
1736
1737         /* Expect step 1 packet from peer */
1738         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1,
1739             input_userauth_jpake_server_step1);
1740
1741         return 1;
1742 }
1743
1744 void
1745 userauth_jpake_cleanup(Authctxt *authctxt)
1746 {
1747         debug3("%s: clean up", __func__);
1748         if (authctxt->methoddata != NULL) {
1749                 jpake_free(authctxt->methoddata);
1750                 authctxt->methoddata = NULL;
1751         }
1752 }
1753 #endif /* JPAKE */
1754
1755 /* find auth method */
1756
1757 /*
1758  * given auth method name, if configurable options permit this method fill
1759  * in auth_ident field and return true, otherwise return false.
1760  */
1761 static int
1762 authmethod_is_enabled(Authmethod *method)
1763 {
1764         if (method == NULL)
1765                 return 0;
1766         /* return false if options indicate this method is disabled */
1767         if  (method->enabled == NULL || *method->enabled == 0)
1768                 return 0;
1769         /* return false if batch mode is enabled but method needs interactive mode */
1770         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1771                 return 0;
1772         return 1;
1773 }
1774
1775 static Authmethod *
1776 authmethod_lookup(const char *name)
1777 {
1778         Authmethod *method = NULL;
1779         if (name != NULL)
1780                 for (method = authmethods; method->name != NULL; method++)
1781                         if (strcmp(name, method->name) == 0)
1782                                 return method;
1783         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1784         return NULL;
1785 }
1786
1787 /* XXX internal state */
1788 static Authmethod *current = NULL;
1789 static char *supported = NULL;
1790 static char *preferred = NULL;
1791
1792 /*
1793  * Given the authentication method list sent by the server, return the
1794  * next method we should try.  If the server initially sends a nil list,
1795  * use a built-in default list.
1796  */
1797 static Authmethod *
1798 authmethod_get(char *authlist)
1799 {
1800         char *name = NULL;
1801         u_int next;
1802
1803         /* Use a suitable default if we're passed a nil list.  */
1804         if (authlist == NULL || strlen(authlist) == 0)
1805                 authlist = options.preferred_authentications;
1806
1807         if (supported == NULL || strcmp(authlist, supported) != 0) {
1808                 debug3("start over, passed a different list %s", authlist);
1809                 if (supported != NULL)
1810                         xfree(supported);
1811                 supported = xstrdup(authlist);
1812                 preferred = options.preferred_authentications;
1813                 debug3("preferred %s", preferred);
1814                 current = NULL;
1815         } else if (current != NULL && authmethod_is_enabled(current))
1816                 return current;
1817
1818         for (;;) {
1819                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1820                         debug("No more authentication methods to try.");
1821                         current = NULL;
1822                         return NULL;
1823                 }
1824                 preferred += next;
1825                 debug3("authmethod_lookup %s", name);
1826                 debug3("remaining preferred: %s", preferred);
1827                 if ((current = authmethod_lookup(name)) != NULL &&
1828                     authmethod_is_enabled(current)) {
1829                         debug3("authmethod_is_enabled %s", name);
1830                         debug("Next authentication method: %s", name);
1831                         return current;
1832                 }
1833         }
1834 }
1835
1836 static char *
1837 authmethods_get(void)
1838 {
1839         Authmethod *method = NULL;
1840         Buffer b;
1841         char *list;
1842
1843         buffer_init(&b);
1844         for (method = authmethods; method->name != NULL; method++) {
1845                 if (authmethod_is_enabled(method)) {
1846                         if (buffer_len(&b) > 0)
1847                                 buffer_append(&b, ",", 1);
1848                         buffer_append(&b, method->name, strlen(method->name));
1849                 }
1850         }
1851         buffer_append(&b, "\0", 1);
1852         list = xstrdup(buffer_ptr(&b));
1853         buffer_free(&b);
1854         return list;
1855 }
1856