crypto/openssh/sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.204 2014/02/02 03:44:32 djm Exp $ */
   2 /* $FreeBSD$ */
   3 /*
   4  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   5  * Copyright (c) 2008 Damien Miller.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 #include "includes.h"
  29 __RCSID("$FreeBSD$");
  30
  31 #include <sys/types.h>
  32 #include <sys/socket.h>
  33 #include <sys/wait.h>
  34 #include <sys/stat.h>
  35
  36 #include <errno.h>
  37 #include <fcntl.h>
  38 #include <netdb.h>
  39 #include <pwd.h>
  40 #include <signal.h>
  41 #include <stdarg.h>
  42 #include <stdio.h>
  43 #include <string.h>
  44 #include <unistd.h>
  45 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS)
  46 #include <vis.h>
  47 #endif
  48
  49 #include "openbsd-compat/sys-queue.h"
  50
  51 #include "xmalloc.h"
  52 #include "ssh.h"
  53 #include "ssh2.h"
  54 #include "buffer.h"
  55 #include "packet.h"
  56 #include "compat.h"
  57 #include "cipher.h"
  58 #include "key.h"
  59 #include "kex.h"
  60 #include "myproposal.h"
  61 #include "sshconnect.h"
  62 #include "authfile.h"
  63 #include "dh.h"
  64 #include "authfd.h"
  65 #include "log.h"
  66 #include "readconf.h"
  67 #include "misc.h"
  68 #include "match.h"
  69 #include "dispatch.h"
  70 #include "canohost.h"
  71 #include "msg.h"
  72 #include "pathnames.h"
  73 #include "uidswap.h"
  74 #include "hostfile.h"
  75
  76 #ifdef GSSAPI
  77 #include "ssh-gss.h"
  78 #endif
  79
  80 /* import */
  81 extern char *client_version_string;
  82 extern char *server_version_string;
  83 extern Options options;
  84 #ifdef  NONE_CIPHER_ENABLED
  85 extern Kex *xxx_kex;
  86
  87 /*
  88  * tty_flag is set in ssh.c so we can use it here.  If set then prevent
  89  * the switch to the null cipher.
  90  */
  91
  92 extern int tty_flag;
  93 #endif
  94
  95 /*
  96  * SSH2 key exchange
  97  */
  98
  99 u_char *session_id2 = NULL;
 100 u_int session_id2_len = 0;
 101
 102 char *xxx_host;
 103 struct sockaddr *xxx_hostaddr;
 104
 105 Kex *xxx_kex = NULL;
 106
 107 static int
 108 verify_host_key_callback(Key *hostkey)
 109 {
 110         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
 111                 fatal("Host key verification failed.");
 112         return 0;
 113 }
 114
 115 static char *
 116 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
 117 {
 118         char *oavail, *avail, *first, *last, *alg, *hostname, *ret;
 119         size_t maxlen;
 120         struct hostkeys *hostkeys;
 121         int ktype;
 122         u_int i;
 123
 124         /* Find all hostkeys for this hostname */
 125         get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
 126         hostkeys = init_hostkeys();
 127         for (i = 0; i < options.num_user_hostfiles; i++)
 128                 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]);
 129         for (i = 0; i < options.num_system_hostfiles; i++)
 130                 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]);
 131
 132         oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG);
 133         maxlen = strlen(avail) + 1;
 134         first = xmalloc(maxlen);
 135         last = xmalloc(maxlen);
 136         *first = *last = '\0';
 137
 138 #define ALG_APPEND(to, from) \
 139         do { \
 140                 if (*to != '\0') \
 141                         strlcat(to, ",", maxlen); \
 142                 strlcat(to, from, maxlen); \
 143         } while (0)
 144
 145         while ((alg = strsep(&avail, ",")) && *alg != '\0') {
 146                 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC)
 147                         fatal("%s: unknown alg %s", __func__, alg);
 148                 if (lookup_key_in_hostkeys_by_type(hostkeys,
 149                     key_type_plain(ktype), NULL))
 150                         ALG_APPEND(first, alg);
 151                 else
 152                         ALG_APPEND(last, alg);
 153         }
 154 #undef ALG_APPEND
 155         xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last);
 156         if (*first != '\0')
 157                 debug3("%s: prefer hostkeyalgs: %s", __func__, first);
 158
 159         free(first);
 160         free(last);
 161         free(hostname);
 162         free(oavail);
 163         free_hostkeys(hostkeys);
 164
 165         return ret;
 166 }
 167
 168 void
 169 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
 170 {
 171         Kex *kex;
 172
 173         xxx_host = host;
 174         xxx_hostaddr = hostaddr;
 175
 176         if (options.ciphers == (char *)-1) {
 177                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 178                 options.ciphers = NULL;
 179         }
 180         if (options.ciphers != NULL) {
 181                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 182                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 183         }
 184         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 185             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 186         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 187             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 188         if (options.compression) {
 189                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 190                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 191         } else {
 192                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 193                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 194         }
 195         if (options.macs != NULL) {
 196                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 197                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 198         }
 199         if (options.hostkeyalgorithms != NULL)
 200                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 201                     compat_pkalg_proposal(options.hostkeyalgorithms);
 202         else {
 203                 /* Prefer algorithms that we already have keys for */
 204                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 205                     compat_pkalg_proposal(
 206                     order_hostkeyalgs(host, hostaddr, port));
 207         }
 208         if (options.kex_algorithms != NULL)
 209                 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
 210
 211         if (options.rekey_limit || options.rekey_interval)
 212                 packet_set_rekey_limits((u_int32_t)options.rekey_limit,
 213                     (time_t)options.rekey_interval);
 214
 215         /* start key exchange */
 216         kex = kex_setup(myproposal);
 217         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 218         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 219         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 220         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 221         kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
 222         kex->kex[KEX_C25519_SHA256] = kexc25519_client;
 223         kex->client_version_string=client_version_string;
 224         kex->server_version_string=server_version_string;
 225         kex->verify_host_key=&verify_host_key_callback;
 226
 227         xxx_kex = kex;
 228
 229         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 230
 231         if (options.use_roaming && !kex->roaming) {
 232                 debug("Roaming not allowed by server");
 233                 options.use_roaming = 0;
 234         }
 235
 236         session_id2 = kex->session_id;
 237         session_id2_len = kex->session_id_len;
 238
 239 #ifdef DEBUG_KEXDH
 240         /* send 1st encrypted/maced/compressed message */
 241         packet_start(SSH2_MSG_IGNORE);
 242         packet_put_cstring("markus");
 243         packet_send();
 244         packet_write_wait();
 245 #endif
 246 }
 247
 248 /*
 249  * Authenticate user
 250  */
 251
 252 typedef struct Authctxt Authctxt;
 253 typedef struct Authmethod Authmethod;
 254 typedef struct identity Identity;
 255 typedef struct idlist Idlist;
 256
 257 struct identity {
 258         TAILQ_ENTRY(identity) next;
 259         AuthenticationConnection *ac;   /* set if agent supports key */
 260         Key     *key;                   /* public/private key */
 261         char    *filename;              /* comment for agent-only keys */
 262         int     tried;
 263         int     isprivate;              /* key points to the private key */
 264         int     userprovided;
 265 };
 266 TAILQ_HEAD(idlist, identity);
 267
 268 struct Authctxt {
 269         const char *server_user;
 270         const char *local_user;
 271         const char *host;
 272         const char *service;
 273         Authmethod *method;
 274         sig_atomic_t success;
 275         char *authlist;
 276         /* pubkey */
 277         Idlist keys;
 278         AuthenticationConnection *agent;
 279         /* hostbased */
 280         Sensitive *sensitive;
 281         /* kbd-interactive */
 282         int info_req_seen;
 283         /* generic */
 284         void *methoddata;
 285 };
 286 struct Authmethod {
 287         char    *name;          /* string to compare against server's list */
 288         int     (*userauth)(Authctxt *authctxt);
 289         void    (*cleanup)(Authctxt *authctxt);
 290         int     *enabled;       /* flag in option struct that enables method */
 291         int     *batch_flag;    /* flag in option struct that disables method */
 292 };
 293
 294 void    input_userauth_success(int, u_int32_t, void *);
 295 void    input_userauth_success_unexpected(int, u_int32_t, void *);
 296 void    input_userauth_failure(int, u_int32_t, void *);
 297 void    input_userauth_banner(int, u_int32_t, void *);
 298 void    input_userauth_error(int, u_int32_t, void *);
 299 void    input_userauth_info_req(int, u_int32_t, void *);
 300 void    input_userauth_pk_ok(int, u_int32_t, void *);
 301 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 302
 303 int     userauth_none(Authctxt *);
 304 int     userauth_pubkey(Authctxt *);
 305 int     userauth_passwd(Authctxt *);
 306 int     userauth_kbdint(Authctxt *);
 307 int     userauth_hostbased(Authctxt *);
 308
 309 #ifdef GSSAPI
 310 int     userauth_gssapi(Authctxt *authctxt);
 311 void    input_gssapi_response(int type, u_int32_t, void *);
 312 void    input_gssapi_token(int type, u_int32_t, void *);
 313 void    input_gssapi_hash(int type, u_int32_t, void *);
 314 void    input_gssapi_error(int, u_int32_t, void *);
 315 void    input_gssapi_errtok(int, u_int32_t, void *);
 316 #endif
 317
 318 void    userauth(Authctxt *, char *);
 319
 320 static int sign_and_send_pubkey(Authctxt *, Identity *);
 321 static void pubkey_prepare(Authctxt *);
 322 static void pubkey_cleanup(Authctxt *);
 323 static Key *load_identity_file(char *, int);
 324
 325 static Authmethod *authmethod_get(char *authlist);
 326 static Authmethod *authmethod_lookup(const char *name);
 327 static char *authmethods_get(void);
 328
 329 Authmethod authmethods[] = {
 330 #ifdef GSSAPI
 331         {"gssapi-with-mic",
 332                 userauth_gssapi,
 333                 NULL,
 334                 &options.gss_authentication,
 335                 NULL},
 336 #endif
 337         {"hostbased",
 338                 userauth_hostbased,
 339                 NULL,
 340                 &options.hostbased_authentication,
 341                 NULL},
 342         {"publickey",
 343                 userauth_pubkey,
 344                 NULL,
 345                 &options.pubkey_authentication,
 346                 NULL},
 347         {"keyboard-interactive",
 348                 userauth_kbdint,
 349                 NULL,
 350                 &options.kbd_interactive_authentication,
 351                 &options.batch_mode},
 352         {"password",
 353                 userauth_passwd,
 354                 NULL,
 355                 &options.password_authentication,
 356                 &options.batch_mode},
 357         {"none",
 358                 userauth_none,
 359                 NULL,
 360                 NULL,
 361                 NULL},
 362         {NULL, NULL, NULL, NULL, NULL}
 363 };
 364
 365 void
 366 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 367     Sensitive *sensitive)
 368 {
 369         Authctxt authctxt;
 370         int type;
 371
 372         if (options.challenge_response_authentication)
 373                 options.kbd_interactive_authentication = 1;
 374
 375         packet_start(SSH2_MSG_SERVICE_REQUEST);
 376         packet_put_cstring("ssh-userauth");
 377         packet_send();
 378         debug("SSH2_MSG_SERVICE_REQUEST sent");
 379         packet_write_wait();
 380         type = packet_read();
 381         if (type != SSH2_MSG_SERVICE_ACCEPT)
 382                 fatal("Server denied authentication request: %d", type);
 383         if (packet_remaining() > 0) {
 384                 char *reply = packet_get_string(NULL);
 385                 debug2("service_accept: %s", reply);
 386                 free(reply);
 387         } else {
 388                 debug2("buggy server: service_accept w/o service");
 389         }
 390         packet_check_eom();
 391         debug("SSH2_MSG_SERVICE_ACCEPT received");
 392
 393         if (options.preferred_authentications == NULL)
 394                 options.preferred_authentications = authmethods_get();
 395
 396         /* setup authentication context */
 397         memset(&authctxt, 0, sizeof(authctxt));
 398         pubkey_prepare(&authctxt);
 399         authctxt.server_user = server_user;
 400         authctxt.local_user = local_user;
 401         authctxt.host = host;
 402         authctxt.service = "ssh-connection";            /* service name */
 403         authctxt.success = 0;
 404         authctxt.method = authmethod_lookup("none");
 405         authctxt.authlist = NULL;
 406         authctxt.methoddata = NULL;
 407         authctxt.sensitive = sensitive;
 408         authctxt.info_req_seen = 0;
 409         if (authctxt.method == NULL)
 410                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 411
 412         /* initial userauth request */
 413         userauth_none(&authctxt);
 414
 415         dispatch_init(&input_userauth_error);
 416         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 417         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 418         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 419         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 420
 421         pubkey_cleanup(&authctxt);
 422         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 423
 424 #ifdef  NONE_CIPHER_ENABLED
 425         /*
 426          * If the user explicitly requests to use the none cipher enable it
 427          * post authentication and only if the right conditions are met: both
 428          * of the NONE switches must be true and there must be no tty allocated.
 429          */
 430         if (options.none_switch == 1 && options.none_enabled == 1) {
 431                 if (!tty_flag) {
 432                         debug("Requesting none cipher re-keying...");
 433                         myproposal[PROPOSAL_ENC_ALGS_STOC] = "none";
 434                         myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none";
 435                         kex_prop2buf(&xxx_kex->my, myproposal);
 436                         packet_request_rekeying();
 437                         fprintf(stderr, "WARNING: enabled NONE cipher\n");
 438                 } else {
 439                         /* Requested NONE cipher on an interactive session. */
 440                         debug("Cannot switch to NONE cipher with tty "
 441                             "allocated");
 442                         fprintf(stderr, "NONE cipher switch disabled given "
 443                             "a TTY is allocated\n");
 444                 }
 445         }
 446 #endif
 447         debug("Authentication succeeded (%s).", authctxt.method->name);
 448 }
 449
 450 void
 451 userauth(Authctxt *authctxt, char *authlist)
 452 {
 453         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 454                 authctxt->method->cleanup(authctxt);
 455
 456         free(authctxt->methoddata);
 457         authctxt->methoddata = NULL;
 458         if (authlist == NULL) {
 459                 authlist = authctxt->authlist;
 460         } else {
 461                 free(authctxt->authlist);
 462                 authctxt->authlist = authlist;
 463         }
 464         for (;;) {
 465                 Authmethod *method = authmethod_get(authlist);
 466                 if (method == NULL)
 467                         fatal("Permission denied (%s).", authlist);
 468                 authctxt->method = method;
 469
 470                 /* reset the per method handler */
 471                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 472                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 473
 474                 /* and try new method */
 475                 if (method->userauth(authctxt) != 0) {
 476                         debug2("we sent a %s packet, wait for reply", method->name);
 477                         break;
 478                 } else {
 479                         debug2("we did not send a packet, disable method");
 480                         method->enabled = NULL;
 481                 }
 482         }
 483 }
 484
 485 /* ARGSUSED */
 486 void
 487 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 488 {
 489         fatal("input_userauth_error: bad message during authentication: "
 490             "type %d", type);
 491 }
 492
 493 /* ARGSUSED */
 494 void
 495 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 496 {
 497         char *msg, *raw, *lang;
 498         u_int len;
 499
 500         debug3("input_userauth_banner");
 501         raw = packet_get_string(&len);
 502         lang = packet_get_string(NULL);
 503         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
 504                 if (len > 65536)
 505                         len = 65536;
 506                 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
 507                 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH);
 508                 fprintf(stderr, "%s", msg);
 509                 free(msg);
 510         }
 511         free(raw);
 512         free(lang);
 513 }
 514
 515 /* ARGSUSED */
 516 void
 517 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 518 {
 519         Authctxt *authctxt = ctxt;
 520
 521         if (authctxt == NULL)
 522                 fatal("input_userauth_success: no authentication context");
 523         free(authctxt->authlist);
 524         authctxt->authlist = NULL;
 525         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 526                 authctxt->method->cleanup(authctxt);
 527         free(authctxt->methoddata);
 528         authctxt->methoddata = NULL;
 529         authctxt->success = 1;                  /* break out */
 530 }
 531
 532 void
 533 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
 534 {
 535         Authctxt *authctxt = ctxt;
 536
 537         if (authctxt == NULL)
 538                 fatal("%s: no authentication context", __func__);
 539
 540         fatal("Unexpected authentication success during %s.",
 541             authctxt->method->name);
 542 }
 543
 544 /* ARGSUSED */
 545 void
 546 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 547 {
 548         Authctxt *authctxt = ctxt;
 549         char *authlist = NULL;
 550         int partial;
 551
 552         if (authctxt == NULL)
 553                 fatal("input_userauth_failure: no authentication context");
 554
 555         authlist = packet_get_string(NULL);
 556         partial = packet_get_char();
 557         packet_check_eom();
 558
 559         if (partial != 0) {
 560                 logit("Authenticated with partial success.");
 561                 /* reset state */
 562                 pubkey_cleanup(authctxt);
 563                 pubkey_prepare(authctxt);
 564         }
 565         debug("Authentications that can continue: %s", authlist);
 566
 567         userauth(authctxt, authlist);
 568 }
 569
 570 /* ARGSUSED */
 571 void
 572 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 573 {
 574         Authctxt *authctxt = ctxt;
 575         Key *key = NULL;
 576         Identity *id = NULL;
 577         Buffer b;
 578         int pktype, sent = 0;
 579         u_int alen, blen;
 580         char *pkalg, *fp;
 581         u_char *pkblob;
 582
 583         if (authctxt == NULL)
 584                 fatal("input_userauth_pk_ok: no authentication context");
 585         if (datafellows & SSH_BUG_PKOK) {
 586                 /* this is similar to SSH_BUG_PKAUTH */
 587                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 588                 pkblob = packet_get_string(&blen);
 589                 buffer_init(&b);
 590                 buffer_append(&b, pkblob, blen);
 591                 pkalg = buffer_get_string(&b, &alen);
 592                 buffer_free(&b);
 593         } else {
 594                 pkalg = packet_get_string(&alen);
 595                 pkblob = packet_get_string(&blen);
 596         }
 597         packet_check_eom();
 598
 599         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 600
 601         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 602                 debug("unknown pkalg %s", pkalg);
 603                 goto done;
 604         }
 605         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 606                 debug("no key from blob. pkalg %s", pkalg);
 607                 goto done;
 608         }
 609         if (key->type != pktype) {
 610                 error("input_userauth_pk_ok: type mismatch "
 611                     "for decoded key (received %d, expected %d)",
 612                     key->type, pktype);
 613                 goto done;
 614         }
 615         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 616         debug2("input_userauth_pk_ok: fp %s", fp);
 617         free(fp);
 618
 619         /*
 620          * search keys in the reverse order, because last candidate has been
 621          * moved to the end of the queue.  this also avoids confusion by
 622          * duplicate keys
 623          */
 624         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 625                 if (key_equal(key, id->key)) {
 626                         sent = sign_and_send_pubkey(authctxt, id);
 627                         break;
 628                 }
 629         }
 630 done:
 631         if (key != NULL)
 632                 key_free(key);
 633         free(pkalg);
 634         free(pkblob);
 635
 636         /* try another method if we did not send a packet */
 637         if (sent == 0)
 638                 userauth(authctxt, NULL);
 639 }
 640
 641 #ifdef GSSAPI
 642 int
 643 userauth_gssapi(Authctxt *authctxt)
 644 {
 645         Gssctxt *gssctxt = NULL;
 646         static gss_OID_set gss_supported = NULL;
 647         static u_int mech = 0;
 648         OM_uint32 min;
 649         int ok = 0;
 650
 651         /* Try one GSSAPI method at a time, rather than sending them all at
 652          * once. */
 653
 654         if (gss_supported == NULL)
 655                 gss_indicate_mechs(&min, &gss_supported);
 656
 657         /* Check to see if the mechanism is usable before we offer it */
 658         while (mech < gss_supported->count && !ok) {
 659                 /* My DER encoding requires length<128 */
 660                 if (gss_supported->elements[mech].length < 128 &&
 661                     ssh_gssapi_check_mechanism(&gssctxt,
 662                     &gss_supported->elements[mech], authctxt->host)) {
 663                         ok = 1; /* Mechanism works */
 664                 } else {
 665                         mech++;
 666                 }
 667         }
 668
 669         if (!ok)
 670                 return 0;
 671
 672         authctxt->methoddata=(void *)gssctxt;
 673
 674         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 675         packet_put_cstring(authctxt->server_user);
 676         packet_put_cstring(authctxt->service);
 677         packet_put_cstring(authctxt->method->name);
 678
 679         packet_put_int(1);
 680
 681         packet_put_int((gss_supported->elements[mech].length) + 2);
 682         packet_put_char(SSH_GSS_OIDTYPE);
 683         packet_put_char(gss_supported->elements[mech].length);
 684         packet_put_raw(gss_supported->elements[mech].elements,
 685             gss_supported->elements[mech].length);
 686
 687         packet_send();
 688
 689         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 690         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 691         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 692         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 693
 694         mech++; /* Move along to next candidate */
 695
 696         return 1;
 697 }
 698
 699 static OM_uint32
 700 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 701 {
 702         Authctxt *authctxt = ctxt;
 703         Gssctxt *gssctxt = authctxt->methoddata;
 704         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 705         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 706         gss_buffer_desc gssbuf;
 707         OM_uint32 status, ms, flags;
 708         Buffer b;
 709
 710         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 711             recv_tok, &send_tok, &flags);
 712
 713         if (send_tok.length > 0) {
 714                 if (GSS_ERROR(status))
 715                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 716                 else
 717                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 718
 719                 packet_put_string(send_tok.value, send_tok.length);
 720                 packet_send();
 721                 gss_release_buffer(&ms, &send_tok);
 722         }
 723
 724         if (status == GSS_S_COMPLETE) {
 725                 /* send either complete or MIC, depending on mechanism */
 726                 if (!(flags & GSS_C_INTEG_FLAG)) {
 727                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 728                         packet_send();
 729                 } else {
 730                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 731                             authctxt->service, "gssapi-with-mic");
 732
 733                         gssbuf.value = buffer_ptr(&b);
 734                         gssbuf.length = buffer_len(&b);
 735
 736                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 737
 738                         if (!GSS_ERROR(status)) {
 739                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 740                                 packet_put_string(mic.value, mic.length);
 741
 742                                 packet_send();
 743                         }
 744
 745                         buffer_free(&b);
 746                         gss_release_buffer(&ms, &mic);
 747                 }
 748         }
 749
 750         return status;
 751 }
 752
 753 /* ARGSUSED */
 754 void
 755 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 756 {
 757         Authctxt *authctxt = ctxt;
 758         Gssctxt *gssctxt;
 759         int oidlen;
 760         char *oidv;
 761
 762         if (authctxt == NULL)
 763                 fatal("input_gssapi_response: no authentication context");
 764         gssctxt = authctxt->methoddata;
 765
 766         /* Setup our OID */
 767         oidv = packet_get_string(&oidlen);
 768
 769         if (oidlen <= 2 ||
 770             oidv[0] != SSH_GSS_OIDTYPE ||
 771             oidv[1] != oidlen - 2) {
 772                 free(oidv);
 773                 debug("Badly encoded mechanism OID received");
 774                 userauth(authctxt, NULL);
 775                 return;
 776         }
 777
 778         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 779                 fatal("Server returned different OID than expected");
 780
 781         packet_check_eom();
 782
 783         free(oidv);
 784
 785         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 786                 /* Start again with next method on list */
 787                 debug("Trying to start again");
 788                 userauth(authctxt, NULL);
 789                 return;
 790         }
 791 }
 792
 793 /* ARGSUSED */
 794 void
 795 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 796 {
 797         Authctxt *authctxt = ctxt;
 798         gss_buffer_desc recv_tok;
 799         OM_uint32 status;
 800         u_int slen;
 801
 802         if (authctxt == NULL)
 803                 fatal("input_gssapi_response: no authentication context");
 804
 805         recv_tok.value = packet_get_string(&slen);
 806         recv_tok.length = slen; /* safe typecast */
 807
 808         packet_check_eom();
 809
 810         status = process_gssapi_token(ctxt, &recv_tok);
 811
 812         free(recv_tok.value);
 813
 814         if (GSS_ERROR(status)) {
 815                 /* Start again with the next method in the list */
 816                 userauth(authctxt, NULL);
 817                 return;
 818         }
 819 }
 820
 821 /* ARGSUSED */
 822 void
 823 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 824 {
 825         Authctxt *authctxt = ctxt;
 826         Gssctxt *gssctxt;
 827         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 828         gss_buffer_desc recv_tok;
 829         OM_uint32 ms;
 830         u_int len;
 831
 832         if (authctxt == NULL)
 833                 fatal("input_gssapi_response: no authentication context");
 834         gssctxt = authctxt->methoddata;
 835
 836         recv_tok.value = packet_get_string(&len);
 837         recv_tok.length = len;
 838
 839         packet_check_eom();
 840
 841         /* Stick it into GSSAPI and see what it says */
 842         (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 843             &recv_tok, &send_tok, NULL);
 844
 845         free(recv_tok.value);
 846         gss_release_buffer(&ms, &send_tok);
 847
 848         /* Server will be returning a failed packet after this one */
 849 }
 850
 851 /* ARGSUSED */
 852 void
 853 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 854 {
 855         char *msg;
 856         char *lang;
 857
 858         /* maj */(void)packet_get_int();
 859         /* min */(void)packet_get_int();
 860         msg=packet_get_string(NULL);
 861         lang=packet_get_string(NULL);
 862
 863         packet_check_eom();
 864
 865         debug("Server GSSAPI Error:\n%s", msg);
 866         free(msg);
 867         free(lang);
 868 }
 869 #endif /* GSSAPI */
 870
 871 int
 872 userauth_none(Authctxt *authctxt)
 873 {
 874         /* initial userauth request */
 875         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 876         packet_put_cstring(authctxt->server_user);
 877         packet_put_cstring(authctxt->service);
 878         packet_put_cstring(authctxt->method->name);
 879         packet_send();
 880         return 1;
 881 }
 882
 883 int
 884 userauth_passwd(Authctxt *authctxt)
 885 {
 886         static int attempt = 0;
 887         char prompt[150];
 888         char *password;
 889         const char *host = options.host_key_alias ?  options.host_key_alias :
 890             authctxt->host;
 891
 892         if (attempt++ >= options.number_of_password_prompts)
 893                 return 0;
 894
 895         if (attempt != 1)
 896                 error("Permission denied, please try again.");
 897
 898         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 899             authctxt->server_user, host);
 900         password = read_passphrase(prompt, 0);
 901         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 902         packet_put_cstring(authctxt->server_user);
 903         packet_put_cstring(authctxt->service);
 904         packet_put_cstring(authctxt->method->name);
 905         packet_put_char(0);
 906         packet_put_cstring(password);
 907         explicit_bzero(password, strlen(password));
 908         free(password);
 909         packet_add_padding(64);
 910         packet_send();
 911
 912         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 913             &input_userauth_passwd_changereq);
 914
 915         return 1;
 916 }
 917
 918 /*
 919  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 920  */
 921 /* ARGSUSED */
 922 void
 923 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 924 {
 925         Authctxt *authctxt = ctxt;
 926         char *info, *lang, *password = NULL, *retype = NULL;
 927         char prompt[150];
 928         const char *host = options.host_key_alias ? options.host_key_alias :
 929             authctxt->host;
 930
 931         debug2("input_userauth_passwd_changereq");
 932
 933         if (authctxt == NULL)
 934                 fatal("input_userauth_passwd_changereq: "
 935                     "no authentication context");
 936
 937         info = packet_get_string(NULL);
 938         lang = packet_get_string(NULL);
 939         if (strlen(info) > 0)
 940                 logit("%s", info);
 941         free(info);
 942         free(lang);
 943         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 944         packet_put_cstring(authctxt->server_user);
 945         packet_put_cstring(authctxt->service);
 946         packet_put_cstring(authctxt->method->name);
 947         packet_put_char(1);                     /* additional info */
 948         snprintf(prompt, sizeof(prompt),
 949             "Enter %.30s@%.128s's old password: ",
 950             authctxt->server_user, host);
 951         password = read_passphrase(prompt, 0);
 952         packet_put_cstring(password);
 953         explicit_bzero(password, strlen(password));
 954         free(password);
 955         password = NULL;
 956         while (password == NULL) {
 957                 snprintf(prompt, sizeof(prompt),
 958                     "Enter %.30s@%.128s's new password: ",
 959                     authctxt->server_user, host);
 960                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 961                 if (password == NULL) {
 962                         /* bail out */
 963                         return;
 964                 }
 965                 snprintf(prompt, sizeof(prompt),
 966                     "Retype %.30s@%.128s's new password: ",
 967                     authctxt->server_user, host);
 968                 retype = read_passphrase(prompt, 0);
 969                 if (strcmp(password, retype) != 0) {
 970                         explicit_bzero(password, strlen(password));
 971                         free(password);
 972                         logit("Mismatch; try again, EOF to quit.");
 973                         password = NULL;
 974                 }
 975                 explicit_bzero(retype, strlen(retype));
 976                 free(retype);
 977         }
 978         packet_put_cstring(password);
 979         explicit_bzero(password, strlen(password));
 980         free(password);
 981         packet_add_padding(64);
 982         packet_send();
 983
 984         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 985             &input_userauth_passwd_changereq);
 986 }
 987
 988 static int
 989 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
 990     u_char *data, u_int datalen)
 991 {
 992         Key *prv;
 993         int ret;
 994
 995         /* the agent supports this key */
 996         if (id->ac)
 997                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
 998                     data, datalen));
 999         /*
1000          * we have already loaded the private key or
1001          * the private key is stored in external hardware
1002          */
1003         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1004                 return (key_sign(id->key, sigp, lenp, data, datalen));
1005         /* load the private key from the file */
1006         if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL)
1007                 return (-1);
1008         ret = key_sign(prv, sigp, lenp, data, datalen);
1009         key_free(prv);
1010         return (ret);
1011 }
1012
1013 static int
1014 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1015 {
1016         Buffer b;
1017         u_char *blob, *signature;
1018         u_int bloblen, slen;
1019         u_int skip = 0;
1020         int ret = -1;
1021         int have_sig = 1;
1022         char *fp;
1023
1024         fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
1025         debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp);
1026         free(fp);
1027
1028         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1029                 /* we cannot handle this key */
1030                 debug3("sign_and_send_pubkey: cannot handle key");
1031                 return 0;
1032         }
1033         /* data to be signed */
1034         buffer_init(&b);
1035         if (datafellows & SSH_OLD_SESSIONID) {
1036                 buffer_append(&b, session_id2, session_id2_len);
1037                 skip = session_id2_len;
1038         } else {
1039                 buffer_put_string(&b, session_id2, session_id2_len);
1040                 skip = buffer_len(&b);
1041         }
1042         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1043         buffer_put_cstring(&b, authctxt->server_user);
1044         buffer_put_cstring(&b,
1045             datafellows & SSH_BUG_PKSERVICE ?
1046             "ssh-userauth" :
1047             authctxt->service);
1048         if (datafellows & SSH_BUG_PKAUTH) {
1049                 buffer_put_char(&b, have_sig);
1050         } else {
1051                 buffer_put_cstring(&b, authctxt->method->name);
1052                 buffer_put_char(&b, have_sig);
1053                 buffer_put_cstring(&b, key_ssh_name(id->key));
1054         }
1055         buffer_put_string(&b, blob, bloblen);
1056
1057         /* generate signature */
1058         ret = identity_sign(id, &signature, &slen,
1059             buffer_ptr(&b), buffer_len(&b));
1060         if (ret == -1) {
1061                 free(blob);
1062                 buffer_free(&b);
1063                 return 0;
1064         }
1065 #ifdef DEBUG_PK
1066         buffer_dump(&b);
1067 #endif
1068         if (datafellows & SSH_BUG_PKSERVICE) {
1069                 buffer_clear(&b);
1070                 buffer_append(&b, session_id2, session_id2_len);
1071                 skip = session_id2_len;
1072                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1073                 buffer_put_cstring(&b, authctxt->server_user);
1074                 buffer_put_cstring(&b, authctxt->service);
1075                 buffer_put_cstring(&b, authctxt->method->name);
1076                 buffer_put_char(&b, have_sig);
1077                 if (!(datafellows & SSH_BUG_PKAUTH))
1078                         buffer_put_cstring(&b, key_ssh_name(id->key));
1079                 buffer_put_string(&b, blob, bloblen);
1080         }
1081         free(blob);
1082
1083         /* append signature */
1084         buffer_put_string(&b, signature, slen);
1085         free(signature);
1086
1087         /* skip session id and packet type */
1088         if (buffer_len(&b) < skip + 1)
1089                 fatal("userauth_pubkey: internal error");
1090         buffer_consume(&b, skip + 1);
1091
1092         /* put remaining data from buffer into packet */
1093         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1094         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1095         buffer_free(&b);
1096         packet_send();
1097
1098         return 1;
1099 }
1100
1101 static int
1102 send_pubkey_test(Authctxt *authctxt, Identity *id)
1103 {
1104         u_char *blob;
1105         u_int bloblen, have_sig = 0;
1106
1107         debug3("send_pubkey_test");
1108
1109         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1110                 /* we cannot handle this key */
1111                 debug3("send_pubkey_test: cannot handle key");
1112                 return 0;
1113         }
1114         /* register callback for USERAUTH_PK_OK message */
1115         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1116
1117         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1118         packet_put_cstring(authctxt->server_user);
1119         packet_put_cstring(authctxt->service);
1120         packet_put_cstring(authctxt->method->name);
1121         packet_put_char(have_sig);
1122         if (!(datafellows & SSH_BUG_PKAUTH))
1123                 packet_put_cstring(key_ssh_name(id->key));
1124         packet_put_string(blob, bloblen);
1125         free(blob);
1126         packet_send();
1127         return 1;
1128 }
1129
1130 static Key *
1131 load_identity_file(char *filename, int userprovided)
1132 {
1133         Key *private;
1134         char prompt[300], *passphrase;
1135         int perm_ok = 0, quit, i;
1136         struct stat st;
1137
1138         if (stat(filename, &st) < 0) {
1139                 (userprovided ? logit : debug3)("no such identity: %s: %s",
1140                     filename, strerror(errno));
1141                 return NULL;
1142         }
1143         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1144         if (!perm_ok) {
1145                 if (private != NULL)
1146                         key_free(private);
1147                 return NULL;
1148         }
1149         if (private == NULL) {
1150                 if (options.batch_mode)
1151                         return NULL;
1152                 snprintf(prompt, sizeof prompt,
1153                     "Enter passphrase for key '%.100s': ", filename);
1154                 for (i = 0; i < options.number_of_password_prompts; i++) {
1155                         passphrase = read_passphrase(prompt, 0);
1156                         if (strcmp(passphrase, "") != 0) {
1157                                 private = key_load_private_type(KEY_UNSPEC,
1158                                     filename, passphrase, NULL, NULL);
1159                                 quit = 0;
1160                         } else {
1161                                 debug2("no passphrase given, try next key");
1162                                 quit = 1;
1163                         }
1164                         explicit_bzero(passphrase, strlen(passphrase));
1165                         free(passphrase);
1166                         if (private != NULL || quit)
1167                                 break;
1168                         debug2("bad passphrase given, try again...");
1169                 }
1170         }
1171         return private;
1172 }
1173
1174 /*
1175  * try keys in the following order:
1176  *      1. agent keys that are found in the config file
1177  *      2. other agent keys
1178  *      3. keys that are only listed in the config file
1179  */
1180 static void
1181 pubkey_prepare(Authctxt *authctxt)
1182 {
1183         Identity *id, *id2, *tmp;
1184         Idlist agent, files, *preferred;
1185         Key *key;
1186         AuthenticationConnection *ac;
1187         char *comment;
1188         int i, found;
1189
1190         TAILQ_INIT(&agent);     /* keys from the agent */
1191         TAILQ_INIT(&files);     /* keys from the config file */
1192         preferred = &authctxt->keys;
1193         TAILQ_INIT(preferred);  /* preferred order of keys */
1194
1195         /* list of keys stored in the filesystem and PKCS#11 */
1196         for (i = 0; i < options.num_identity_files; i++) {
1197                 key = options.identity_keys[i];
1198                 if (key && key->type == KEY_RSA1)
1199                         continue;
1200                 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1201                         continue;
1202                 options.identity_keys[i] = NULL;
1203                 id = xcalloc(1, sizeof(*id));
1204                 id->key = key;
1205                 id->filename = xstrdup(options.identity_files[i]);
1206                 id->userprovided = options.identity_file_userprovided[i];
1207                 TAILQ_INSERT_TAIL(&files, id, next);
1208         }
1209         /* Prefer PKCS11 keys that are explicitly listed */
1210         TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1211                 if (id->key == NULL || (id->key->flags & KEY_FLAG_EXT) == 0)
1212                         continue;
1213                 found = 0;
1214                 TAILQ_FOREACH(id2, &files, next) {
1215                         if (id2->key == NULL ||
1216                             (id2->key->flags & KEY_FLAG_EXT) != 0)
1217                                 continue;
1218                         if (key_equal(id->key, id2->key)) {
1219                                 TAILQ_REMOVE(&files, id, next);
1220                                 TAILQ_INSERT_TAIL(preferred, id, next);
1221                                 found = 1;
1222                                 break;
1223                         }
1224                 }
1225                 /* If IdentitiesOnly set and key not found then don't use it */
1226                 if (!found && options.identities_only) {
1227                         TAILQ_REMOVE(&files, id, next);
1228                         explicit_bzero(id, sizeof(*id));
1229                         free(id);
1230                 }
1231         }
1232         /* list of keys supported by the agent */
1233         if ((ac = ssh_get_authentication_connection())) {
1234                 for (key = ssh_get_first_identity(ac, &comment, 2);
1235                     key != NULL;
1236                     key = ssh_get_next_identity(ac, &comment, 2)) {
1237                         found = 0;
1238                         TAILQ_FOREACH(id, &files, next) {
1239                                 /* agent keys from the config file are preferred */
1240                                 if (key_equal(key, id->key)) {
1241                                         key_free(key);
1242                                         free(comment);
1243                                         TAILQ_REMOVE(&files, id, next);
1244                                         TAILQ_INSERT_TAIL(preferred, id, next);
1245                                         id->ac = ac;
1246                                         found = 1;
1247                                         break;
1248                                 }
1249                         }
1250                         if (!found && !options.identities_only) {
1251                                 id = xcalloc(1, sizeof(*id));
1252                                 id->key = key;
1253                                 id->filename = comment;
1254                                 id->ac = ac;
1255                                 TAILQ_INSERT_TAIL(&agent, id, next);
1256                         }
1257                 }
1258                 /* append remaining agent keys */
1259                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1260                         TAILQ_REMOVE(&agent, id, next);
1261                         TAILQ_INSERT_TAIL(preferred, id, next);
1262                 }
1263                 authctxt->agent = ac;
1264         }
1265         /* append remaining keys from the config file */
1266         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1267                 TAILQ_REMOVE(&files, id, next);
1268                 TAILQ_INSERT_TAIL(preferred, id, next);
1269         }
1270         TAILQ_FOREACH(id, preferred, next) {
1271                 debug2("key: %s (%p),%s", id->filename, id->key,
1272                     id->userprovided ? " explicit" : "");
1273         }
1274 }
1275
1276 static void
1277 pubkey_cleanup(Authctxt *authctxt)
1278 {
1279         Identity *id;
1280
1281         if (authctxt->agent != NULL)
1282                 ssh_close_authentication_connection(authctxt->agent);
1283         for (id = TAILQ_FIRST(&authctxt->keys); id;
1284             id = TAILQ_FIRST(&authctxt->keys)) {
1285                 TAILQ_REMOVE(&authctxt->keys, id, next);
1286                 if (id->key)
1287                         key_free(id->key);
1288                 free(id->filename);
1289                 free(id);
1290         }
1291 }
1292
1293 int
1294 userauth_pubkey(Authctxt *authctxt)
1295 {
1296         Identity *id;
1297         int sent = 0;
1298
1299         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1300                 if (id->tried++)
1301                         return (0);
1302                 /* move key to the end of the queue */
1303                 TAILQ_REMOVE(&authctxt->keys, id, next);
1304                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1305                 /*
1306                  * send a test message if we have the public key. for
1307                  * encrypted keys we cannot do this and have to load the
1308                  * private key instead
1309                  */
1310                 if (id->key != NULL) {
1311                         if (key_type_plain(id->key->type) == KEY_RSA &&
1312                             (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1313                                 debug("Skipped %s key %s for RSA/MD5 server",
1314                                     key_type(id->key), id->filename);
1315                         } else if (id->key->type != KEY_RSA1) {
1316                                 debug("Offering %s public key: %s",
1317                                     key_type(id->key), id->filename);
1318                                 sent = send_pubkey_test(authctxt, id);
1319                         }
1320                 } else {
1321                         debug("Trying private key: %s", id->filename);
1322                         id->key = load_identity_file(id->filename,
1323                             id->userprovided);
1324                         if (id->key != NULL) {
1325                                 id->isprivate = 1;
1326                                 if (key_type_plain(id->key->type) == KEY_RSA &&
1327                                     (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1328                                         debug("Skipped %s key %s for RSA/MD5 "
1329                                             "server", key_type(id->key),
1330                                             id->filename);
1331                                 } else {
1332                                         sent = sign_and_send_pubkey(
1333                                             authctxt, id);
1334                                 }
1335                                 key_free(id->key);
1336                                 id->key = NULL;
1337                         }
1338                 }
1339                 if (sent)
1340                         return (sent);
1341         }
1342         return (0);
1343 }
1344
1345 /*
1346  * Send userauth request message specifying keyboard-interactive method.
1347  */
1348 int
1349 userauth_kbdint(Authctxt *authctxt)
1350 {
1351         static int attempt = 0;
1352
1353         if (attempt++ >= options.number_of_password_prompts)
1354                 return 0;
1355         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1356         if (attempt > 1 && !authctxt->info_req_seen) {
1357                 debug3("userauth_kbdint: disable: no info_req_seen");
1358                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1359                 return 0;
1360         }
1361
1362         debug2("userauth_kbdint");
1363         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1364         packet_put_cstring(authctxt->server_user);
1365         packet_put_cstring(authctxt->service);
1366         packet_put_cstring(authctxt->method->name);
1367         packet_put_cstring("");                                 /* lang */
1368         packet_put_cstring(options.kbd_interactive_devices ?
1369             options.kbd_interactive_devices : "");
1370         packet_send();
1371
1372         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1373         return 1;
1374 }
1375
1376 /*
1377  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1378  */
1379 void
1380 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1381 {
1382         Authctxt *authctxt = ctxt;
1383         char *name, *inst, *lang, *prompt, *response;
1384         u_int num_prompts, i;
1385         int echo = 0;
1386
1387         debug2("input_userauth_info_req");
1388
1389         if (authctxt == NULL)
1390                 fatal("input_userauth_info_req: no authentication context");
1391
1392         authctxt->info_req_seen = 1;
1393
1394         name = packet_get_string(NULL);
1395         inst = packet_get_string(NULL);
1396         lang = packet_get_string(NULL);
1397         if (strlen(name) > 0)
1398                 logit("%s", name);
1399         if (strlen(inst) > 0)
1400                 logit("%s", inst);
1401         free(name);
1402         free(inst);
1403         free(lang);
1404
1405         num_prompts = packet_get_int();
1406         /*
1407          * Begin to build info response packet based on prompts requested.
1408          * We commit to providing the correct number of responses, so if
1409          * further on we run into a problem that prevents this, we have to
1410          * be sure and clean this up and send a correct error response.
1411          */
1412         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1413         packet_put_int(num_prompts);
1414
1415         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1416         for (i = 0; i < num_prompts; i++) {
1417                 prompt = packet_get_string(NULL);
1418                 echo = packet_get_char();
1419
1420                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1421
1422                 packet_put_cstring(response);
1423                 explicit_bzero(response, strlen(response));
1424                 free(response);
1425                 free(prompt);
1426         }
1427         packet_check_eom(); /* done with parsing incoming message. */
1428
1429         packet_add_padding(64);
1430         packet_send();
1431 }
1432
1433 static int
1434 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1435     u_char *data, u_int datalen)
1436 {
1437         Buffer b;
1438         struct stat st;
1439         pid_t pid;
1440         int to[2], from[2], status, version = 2;
1441
1442         debug2("ssh_keysign called");
1443
1444         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1445                 error("ssh_keysign: not installed: %s", strerror(errno));
1446                 return -1;
1447         }
1448         if (fflush(stdout) != 0)
1449                 error("ssh_keysign: fflush: %s", strerror(errno));
1450         if (pipe(to) < 0) {
1451                 error("ssh_keysign: pipe: %s", strerror(errno));
1452                 return -1;
1453         }
1454         if (pipe(from) < 0) {
1455                 error("ssh_keysign: pipe: %s", strerror(errno));
1456                 return -1;
1457         }
1458         if ((pid = fork()) < 0) {
1459                 error("ssh_keysign: fork: %s", strerror(errno));
1460                 return -1;
1461         }
1462         if (pid == 0) {
1463                 /* keep the socket on exec */
1464                 fcntl(packet_get_connection_in(), F_SETFD, 0);
1465                 permanently_drop_suid(getuid());
1466                 close(from[0]);
1467                 if (dup2(from[1], STDOUT_FILENO) < 0)
1468                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1469                 close(to[1]);
1470                 if (dup2(to[0], STDIN_FILENO) < 0)
1471                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1472                 close(from[1]);
1473                 close(to[0]);
1474                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1475                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1476                     strerror(errno));
1477         }
1478         close(from[1]);
1479         close(to[0]);
1480
1481         buffer_init(&b);
1482         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1483         buffer_put_string(&b, data, datalen);
1484         if (ssh_msg_send(to[1], version, &b) == -1)
1485                 fatal("ssh_keysign: couldn't send request");
1486
1487         if (ssh_msg_recv(from[0], &b) < 0) {
1488                 error("ssh_keysign: no reply");
1489                 buffer_free(&b);
1490                 return -1;
1491         }
1492         close(from[0]);
1493         close(to[1]);
1494
1495         while (waitpid(pid, &status, 0) < 0)
1496                 if (errno != EINTR)
1497                         break;
1498
1499         if (buffer_get_char(&b) != version) {
1500                 error("ssh_keysign: bad version");
1501                 buffer_free(&b);
1502                 return -1;
1503         }
1504         *sigp = buffer_get_string(&b, lenp);
1505         buffer_free(&b);
1506
1507         return 0;
1508 }
1509
1510 int
1511 userauth_hostbased(Authctxt *authctxt)
1512 {
1513         Key *private = NULL;
1514         Sensitive *sensitive = authctxt->sensitive;
1515         Buffer b;
1516         u_char *signature, *blob;
1517         char *chost, *pkalg, *p;
1518         const char *service;
1519         u_int blen, slen;
1520         int ok, i, found = 0;
1521
1522         /* check for a useful key */
1523         for (i = 0; i < sensitive->nkeys; i++) {
1524                 private = sensitive->keys[i];
1525                 if (private && private->type != KEY_RSA1) {
1526                         found = 1;
1527                         /* we take and free the key */
1528                         sensitive->keys[i] = NULL;
1529                         break;
1530                 }
1531         }
1532         if (!found) {
1533                 debug("No more client hostkeys for hostbased authentication.");
1534                 return 0;
1535         }
1536         if (key_to_blob(private, &blob, &blen) == 0) {
1537                 key_free(private);
1538                 return 0;
1539         }
1540         /* figure out a name for the client host */
1541         p = get_local_name(packet_get_connection_in());
1542         if (p == NULL) {
1543                 error("userauth_hostbased: cannot get local ipaddr/name");
1544                 key_free(private);
1545                 free(blob);
1546                 return 0;
1547         }
1548         xasprintf(&chost, "%s.", p);
1549         debug2("userauth_hostbased: chost %s", chost);
1550         free(p);
1551
1552         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1553             authctxt->service;
1554         pkalg = xstrdup(key_ssh_name(private));
1555         buffer_init(&b);
1556         /* construct data */
1557         buffer_put_string(&b, session_id2, session_id2_len);
1558         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1559         buffer_put_cstring(&b, authctxt->server_user);
1560         buffer_put_cstring(&b, service);
1561         buffer_put_cstring(&b, authctxt->method->name);
1562         buffer_put_cstring(&b, pkalg);
1563         buffer_put_string(&b, blob, blen);
1564         buffer_put_cstring(&b, chost);
1565         buffer_put_cstring(&b, authctxt->local_user);
1566 #ifdef DEBUG_PK
1567         buffer_dump(&b);
1568 #endif
1569         if (sensitive->external_keysign)
1570                 ok = ssh_keysign(private, &signature, &slen,
1571                     buffer_ptr(&b), buffer_len(&b));
1572         else
1573                 ok = key_sign(private, &signature, &slen,
1574                     buffer_ptr(&b), buffer_len(&b));
1575         key_free(private);
1576         buffer_free(&b);
1577         if (ok != 0) {
1578                 error("key_sign failed");
1579                 free(chost);
1580                 free(pkalg);
1581                 free(blob);
1582                 return 0;
1583         }
1584         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1585         packet_put_cstring(authctxt->server_user);
1586         packet_put_cstring(authctxt->service);
1587         packet_put_cstring(authctxt->method->name);
1588         packet_put_cstring(pkalg);
1589         packet_put_string(blob, blen);
1590         packet_put_cstring(chost);
1591         packet_put_cstring(authctxt->local_user);
1592         packet_put_string(signature, slen);
1593         explicit_bzero(signature, slen);
1594         free(signature);
1595         free(chost);
1596         free(pkalg);
1597         free(blob);
1598
1599         packet_send();
1600         return 1;
1601 }
1602
1603 /* find auth method */
1604
1605 /*
1606  * given auth method name, if configurable options permit this method fill
1607  * in auth_ident field and return true, otherwise return false.
1608  */
1609 static int
1610 authmethod_is_enabled(Authmethod *method)
1611 {
1612         if (method == NULL)
1613                 return 0;
1614         /* return false if options indicate this method is disabled */
1615         if  (method->enabled == NULL || *method->enabled == 0)
1616                 return 0;
1617         /* return false if batch mode is enabled but method needs interactive mode */
1618         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1619                 return 0;
1620         return 1;
1621 }
1622
1623 static Authmethod *
1624 authmethod_lookup(const char *name)
1625 {
1626         Authmethod *method = NULL;
1627         if (name != NULL)
1628                 for (method = authmethods; method->name != NULL; method++)
1629                         if (strcmp(name, method->name) == 0)
1630                                 return method;
1631         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1632         return NULL;
1633 }
1634
1635 /* XXX internal state */
1636 static Authmethod *current = NULL;
1637 static char *supported = NULL;
1638 static char *preferred = NULL;
1639
1640 /*
1641  * Given the authentication method list sent by the server, return the
1642  * next method we should try.  If the server initially sends a nil list,
1643  * use a built-in default list.
1644  */
1645 static Authmethod *
1646 authmethod_get(char *authlist)
1647 {
1648         char *name = NULL;
1649         u_int next;
1650
1651         /* Use a suitable default if we're passed a nil list.  */
1652         if (authlist == NULL || strlen(authlist) == 0)
1653                 authlist = options.preferred_authentications;
1654
1655         if (supported == NULL || strcmp(authlist, supported) != 0) {
1656                 debug3("start over, passed a different list %s", authlist);
1657                 free(supported);
1658                 supported = xstrdup(authlist);
1659                 preferred = options.preferred_authentications;
1660                 debug3("preferred %s", preferred);
1661                 current = NULL;
1662         } else if (current != NULL && authmethod_is_enabled(current))
1663                 return current;
1664
1665         for (;;) {
1666                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1667                         debug("No more authentication methods to try.");
1668                         current = NULL;
1669                         return NULL;
1670                 }
1671                 preferred += next;
1672                 debug3("authmethod_lookup %s", name);
1673                 debug3("remaining preferred: %s", preferred);
1674                 if ((current = authmethod_lookup(name)) != NULL &&
1675                     authmethod_is_enabled(current)) {
1676                         debug3("authmethod_is_enabled %s", name);
1677                         debug("Next authentication method: %s", name);
1678                         free(name);
1679                         return current;
1680                 }
1681                 free(name);
1682         }
1683 }
1684
1685 static char *
1686 authmethods_get(void)
1687 {
1688         Authmethod *method = NULL;
1689         Buffer b;
1690         char *list;
1691
1692         buffer_init(&b);
1693         for (method = authmethods; method->name != NULL; method++) {
1694                 if (authmethod_is_enabled(method)) {
1695                         if (buffer_len(&b) > 0)
1696                                 buffer_append(&b, ",", 1);
1697                         buffer_append(&b, method->name, strlen(method->name));
1698                 }
1699         }
1700         buffer_append(&b, "\0", 1);
1701         list = xstrdup(buffer_ptr(&b));
1702         buffer_free(&b);
1703         return list;
1704 }
1705