sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.255 2017/03/11 23:40:26 djm Exp $ */
   2 /*
   3  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   4  * Copyright (c) 2008 Damien Miller.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include "includes.h"
  28
  29 #include <sys/types.h>
  30 #include <sys/socket.h>
  31 #include <sys/wait.h>
  32 #include <sys/stat.h>
  33
  34 #include <errno.h>
  35 #include <fcntl.h>
  36 #include <netdb.h>
  37 #include <pwd.h>
  38 #include <signal.h>
  39 #include <stdarg.h>
  40 #include <stdio.h>
  41 #include <string.h>
  42 #include <unistd.h>
  43 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS)
  44 #include <vis.h>
  45 #endif
  46
  47 #include "openbsd-compat/sys-queue.h"
  48
  49 #include "xmalloc.h"
  50 #include "ssh.h"
  51 #include "ssh2.h"
  52 #include "buffer.h"
  53 #include "packet.h"
  54 #include "compat.h"
  55 #include "cipher.h"
  56 #include "key.h"
  57 #include "kex.h"
  58 #include "myproposal.h"
  59 #include "sshconnect.h"
  60 #include "authfile.h"
  61 #include "dh.h"
  62 #include "authfd.h"
  63 #include "log.h"
  64 #include "misc.h"
  65 #include "readconf.h"
  66 #include "match.h"
  67 #include "dispatch.h"
  68 #include "canohost.h"
  69 #include "msg.h"
  70 #include "pathnames.h"
  71 #include "uidswap.h"
  72 #include "hostfile.h"
  73 #include "ssherr.h"
  74 #include "utf8.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
  85 /*
  86  * SSH2 key exchange
  87  */
  88
  89 u_char *session_id2 = NULL;
  90 u_int session_id2_len = 0;
  91
  92 char *xxx_host;
  93 struct sockaddr *xxx_hostaddr;
  94
  95 static int
  96 verify_host_key_callback(Key *hostkey, struct ssh *ssh)
  97 {
  98         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
  99                 fatal("Host key verification failed.");
 100         return 0;
 101 }
 102
 103 static char *
 104 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
 105 {
 106         char *oavail, *avail, *first, *last, *alg, *hostname, *ret;
 107         size_t maxlen;
 108         struct hostkeys *hostkeys;
 109         int ktype;
 110         u_int i;
 111
 112         /* Find all hostkeys for this hostname */
 113         get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
 114         hostkeys = init_hostkeys();
 115         for (i = 0; i < options.num_user_hostfiles; i++)
 116                 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]);
 117         for (i = 0; i < options.num_system_hostfiles; i++)
 118                 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]);
 119
 120         oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG);
 121         maxlen = strlen(avail) + 1;
 122         first = xmalloc(maxlen);
 123         last = xmalloc(maxlen);
 124         *first = *last = '\0';
 125
 126 #define ALG_APPEND(to, from) \
 127         do { \
 128                 if (*to != '\0') \
 129                         strlcat(to, ",", maxlen); \
 130                 strlcat(to, from, maxlen); \
 131         } while (0)
 132
 133         while ((alg = strsep(&avail, ",")) && *alg != '\0') {
 134                 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC)
 135                         fatal("%s: unknown alg %s", __func__, alg);
 136                 if (lookup_key_in_hostkeys_by_type(hostkeys,
 137                     sshkey_type_plain(ktype), NULL))
 138                         ALG_APPEND(first, alg);
 139                 else
 140                         ALG_APPEND(last, alg);
 141         }
 142 #undef ALG_APPEND
 143         xasprintf(&ret, "%s%s%s", first,
 144             (*first == '\0' || *last == '\0') ? "" : ",", last);
 145         if (*first != '\0')
 146                 debug3("%s: prefer hostkeyalgs: %s", __func__, first);
 147
 148         free(first);
 149         free(last);
 150         free(hostname);
 151         free(oavail);
 152         free_hostkeys(hostkeys);
 153
 154         return ret;
 155 }
 156
 157 void
 158 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
 159 {
 160         char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
 161         char *s;
 162         struct kex *kex;
 163         int r;
 164
 165         xxx_host = host;
 166         xxx_hostaddr = hostaddr;
 167
 168         if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL)
 169                 fatal("%s: kex_names_cat", __func__);
 170         myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s);
 171         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 172             compat_cipher_proposal(options.ciphers);
 173         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 174             compat_cipher_proposal(options.ciphers);
 175         myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 176             myproposal[PROPOSAL_COMP_ALGS_STOC] = options.compression ?
 177             "zlib@openssh.com,zlib,none" : "none,zlib@openssh.com,zlib";
 178         myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 179             myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 180         if (options.hostkeyalgorithms != NULL) {
 181                 if (kex_assemble_names(KEX_DEFAULT_PK_ALG,
 182                     &options.hostkeyalgorithms) != 0)
 183                         fatal("%s: kex_assemble_namelist", __func__);
 184                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 185                     compat_pkalg_proposal(options.hostkeyalgorithms);
 186         } else {
 187                 /* Enforce default */
 188                 options.hostkeyalgorithms = xstrdup(KEX_DEFAULT_PK_ALG);
 189                 /* Prefer algorithms that we already have keys for */
 190                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 191                     compat_pkalg_proposal(
 192                     order_hostkeyalgs(host, hostaddr, port));
 193         }
 194
 195         if (options.rekey_limit || options.rekey_interval)
 196                 packet_set_rekey_limits(options.rekey_limit,
 197                     options.rekey_interval);
 198
 199         /* start key exchange */
 200         if ((r = kex_setup(active_state, myproposal)) != 0)
 201                 fatal("kex_setup: %s", ssh_err(r));
 202         kex = active_state->kex;
 203 #ifdef WITH_OPENSSL
 204         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 205         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 206         kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client;
 207         kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client;
 208         kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client;
 209         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 210         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 211 # ifdef OPENSSL_HAS_ECC
 212         kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
 213 # endif
 214 #endif
 215         kex->kex[KEX_C25519_SHA256] = kexc25519_client;
 216         kex->client_version_string=client_version_string;
 217         kex->server_version_string=server_version_string;
 218         kex->verify_host_key=&verify_host_key_callback;
 219
 220         dispatch_run(DISPATCH_BLOCK, &kex->done, active_state);
 221
 222         /* remove ext-info from the KEX proposals for rekeying */
 223         myproposal[PROPOSAL_KEX_ALGS] =
 224             compat_kex_proposal(options.kex_algorithms);
 225         if ((r = kex_prop2buf(kex->my, myproposal)) != 0)
 226                 fatal("kex_prop2buf: %s", ssh_err(r));
 227
 228         session_id2 = kex->session_id;
 229         session_id2_len = kex->session_id_len;
 230
 231 #ifdef DEBUG_KEXDH
 232         /* send 1st encrypted/maced/compressed message */
 233         packet_start(SSH2_MSG_IGNORE);
 234         packet_put_cstring("markus");
 235         packet_send();
 236         packet_write_wait();
 237 #endif
 238 }
 239
 240 /*
 241  * Authenticate user
 242  */
 243
 244 typedef struct cauthctxt Authctxt;
 245 typedef struct cauthmethod Authmethod;
 246 typedef struct identity Identity;
 247 typedef struct idlist Idlist;
 248
 249 struct identity {
 250         TAILQ_ENTRY(identity) next;
 251         int     agent_fd;               /* >=0 if agent supports key */
 252         struct sshkey   *key;           /* public/private key */
 253         char    *filename;              /* comment for agent-only keys */
 254         int     tried;
 255         int     isprivate;              /* key points to the private key */
 256         int     userprovided;
 257 };
 258 TAILQ_HEAD(idlist, identity);
 259
 260 struct cauthctxt {
 261         const char *server_user;
 262         const char *local_user;
 263         const char *host;
 264         const char *service;
 265         struct cauthmethod *method;
 266         sig_atomic_t success;
 267         char *authlist;
 268         int attempt;
 269         /* pubkey */
 270         struct idlist keys;
 271         int agent_fd;
 272         /* hostbased */
 273         Sensitive *sensitive;
 274         char *oktypes, *ktypes;
 275         const char *active_ktype;
 276         /* kbd-interactive */
 277         int info_req_seen;
 278         /* generic */
 279         void *methoddata;
 280 };
 281
 282 struct cauthmethod {
 283         char    *name;          /* string to compare against server's list */
 284         int     (*userauth)(Authctxt *authctxt);
 285         void    (*cleanup)(Authctxt *authctxt);
 286         int     *enabled;       /* flag in option struct that enables method */
 287         int     *batch_flag;    /* flag in option struct that disables method */
 288 };
 289
 290 int     input_userauth_service_accept(int, u_int32_t, void *);
 291 int     input_userauth_ext_info(int, u_int32_t, void *);
 292 int     input_userauth_success(int, u_int32_t, void *);
 293 int     input_userauth_success_unexpected(int, u_int32_t, void *);
 294 int     input_userauth_failure(int, u_int32_t, void *);
 295 int     input_userauth_banner(int, u_int32_t, void *);
 296 int     input_userauth_error(int, u_int32_t, void *);
 297 int     input_userauth_info_req(int, u_int32_t, void *);
 298 int     input_userauth_pk_ok(int, u_int32_t, void *);
 299 int     input_userauth_passwd_changereq(int, u_int32_t, void *);
 300
 301 int     userauth_none(Authctxt *);
 302 int     userauth_pubkey(Authctxt *);
 303 int     userauth_passwd(Authctxt *);
 304 int     userauth_kbdint(Authctxt *);
 305 int     userauth_hostbased(Authctxt *);
 306
 307 #ifdef GSSAPI
 308 int     userauth_gssapi(Authctxt *authctxt);
 309 int     input_gssapi_response(int type, u_int32_t, void *);
 310 int     input_gssapi_token(int type, u_int32_t, void *);
 311 int     input_gssapi_hash(int type, u_int32_t, void *);
 312 int     input_gssapi_error(int, u_int32_t, void *);
 313 int     input_gssapi_errtok(int, u_int32_t, void *);
 314 #endif
 315
 316 void    userauth(Authctxt *, char *);
 317
 318 static int sign_and_send_pubkey(Authctxt *, Identity *);
 319 static void pubkey_prepare(Authctxt *);
 320 static void pubkey_cleanup(Authctxt *);
 321 static void pubkey_reset(Authctxt *);
 322 static Key *load_identity_file(Identity *);
 323
 324 static Authmethod *authmethod_get(char *authlist);
 325 static Authmethod *authmethod_lookup(const char *name);
 326 static char *authmethods_get(void);
 327
 328 Authmethod authmethods[] = {
 329 #ifdef GSSAPI
 330         {"gssapi-with-mic",
 331                 userauth_gssapi,
 332                 NULL,
 333                 &options.gss_authentication,
 334                 NULL},
 335 #endif
 336         {"hostbased",
 337                 userauth_hostbased,
 338                 NULL,
 339                 &options.hostbased_authentication,
 340                 NULL},
 341         {"publickey",
 342                 userauth_pubkey,
 343                 NULL,
 344                 &options.pubkey_authentication,
 345                 NULL},
 346         {"keyboard-interactive",
 347                 userauth_kbdint,
 348                 NULL,
 349                 &options.kbd_interactive_authentication,
 350                 &options.batch_mode},
 351         {"password",
 352                 userauth_passwd,
 353                 NULL,
 354                 &options.password_authentication,
 355                 &options.batch_mode},
 356         {"none",
 357                 userauth_none,
 358                 NULL,
 359                 NULL,
 360                 NULL},
 361         {NULL, NULL, NULL, NULL, NULL}
 362 };
 363
 364 void
 365 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 366     Sensitive *sensitive)
 367 {
 368         struct ssh *ssh = active_state;
 369         Authctxt authctxt;
 370         int r;
 371
 372         if (options.challenge_response_authentication)
 373                 options.kbd_interactive_authentication = 1;
 374         if (options.preferred_authentications == NULL)
 375                 options.preferred_authentications = authmethods_get();
 376
 377         /* setup authentication context */
 378         memset(&authctxt, 0, sizeof(authctxt));
 379         pubkey_prepare(&authctxt);
 380         authctxt.server_user = server_user;
 381         authctxt.local_user = local_user;
 382         authctxt.host = host;
 383         authctxt.service = "ssh-connection";            /* service name */
 384         authctxt.success = 0;
 385         authctxt.method = authmethod_lookup("none");
 386         authctxt.authlist = NULL;
 387         authctxt.methoddata = NULL;
 388         authctxt.sensitive = sensitive;
 389         authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL;
 390         authctxt.info_req_seen = 0;
 391         authctxt.agent_fd = -1;
 392         if (authctxt.method == NULL)
 393                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 394
 395         if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 ||
 396             (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 ||
 397             (r = sshpkt_send(ssh)) != 0)
 398                 fatal("%s: %s", __func__, ssh_err(r));
 399
 400         ssh_dispatch_init(ssh, &input_userauth_error);
 401         ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info);
 402         ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept);
 403         ssh_dispatch_run(ssh, DISPATCH_BLOCK, &authctxt.success, &authctxt);    /* loop until success */
 404
 405         pubkey_cleanup(&authctxt);
 406         ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 407
 408         if (!authctxt.success)
 409                 fatal("Authentication failed.");
 410         debug("Authentication succeeded (%s).", authctxt.method->name);
 411 }
 412
 413 /* ARGSUSED */
 414 int
 415 input_userauth_service_accept(int type, u_int32_t seqnr, void *ctxt)
 416 {
 417         Authctxt *authctxt = ctxt;
 418         struct ssh *ssh = active_state;
 419         int r;
 420
 421         if (ssh_packet_remaining(ssh) > 0) {
 422                 char *reply;
 423
 424                 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0)
 425                         goto out;
 426                 debug2("service_accept: %s", reply);
 427                 free(reply);
 428         } else {
 429                 debug2("buggy server: service_accept w/o service");
 430         }
 431         if ((r = sshpkt_get_end(ssh)) != 0)
 432                 goto out;
 433         debug("SSH2_MSG_SERVICE_ACCEPT received");
 434
 435         /* initial userauth request */
 436         userauth_none(authctxt);
 437
 438         ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error);
 439         ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 440         ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 441         ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 442         r = 0;
 443  out:
 444         return r;
 445 }
 446
 447 /* ARGSUSED */
 448 int
 449 input_userauth_ext_info(int type, u_int32_t seqnr, void *ctxt)
 450 {
 451         return kex_input_ext_info(type, seqnr, active_state);
 452 }
 453
 454 void
 455 userauth(Authctxt *authctxt, char *authlist)
 456 {
 457         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 458                 authctxt->method->cleanup(authctxt);
 459
 460         free(authctxt->methoddata);
 461         authctxt->methoddata = NULL;
 462         if (authlist == NULL) {
 463                 authlist = authctxt->authlist;
 464         } else {
 465                 free(authctxt->authlist);
 466                 authctxt->authlist = authlist;
 467         }
 468         for (;;) {
 469                 Authmethod *method = authmethod_get(authlist);
 470                 if (method == NULL)
 471                         fatal("Permission denied (%s).", authlist);
 472                 authctxt->method = method;
 473
 474                 /* reset the per method handler */
 475                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 476                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 477
 478                 /* and try new method */
 479                 if (method->userauth(authctxt) != 0) {
 480                         debug2("we sent a %s packet, wait for reply", method->name);
 481                         break;
 482                 } else {
 483                         debug2("we did not send a packet, disable method");
 484                         method->enabled = NULL;
 485                 }
 486         }
 487 }
 488
 489 /* ARGSUSED */
 490 int
 491 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 492 {
 493         fatal("input_userauth_error: bad message during authentication: "
 494             "type %d", type);
 495         return 0;
 496 }
 497
 498 /* ARGSUSED */
 499 int
 500 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 501 {
 502         char *msg, *lang;
 503         u_int len;
 504
 505         debug3("%s", __func__);
 506         msg = packet_get_string(&len);
 507         lang = packet_get_string(NULL);
 508         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO)
 509                 fmprintf(stderr, "%s", msg);
 510         free(msg);
 511         free(lang);
 512         return 0;
 513 }
 514
 515 /* ARGSUSED */
 516 int
 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         return 0;
 531 }
 532
 533 int
 534 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
 535 {
 536         Authctxt *authctxt = ctxt;
 537
 538         if (authctxt == NULL)
 539                 fatal("%s: no authentication context", __func__);
 540
 541         fatal("Unexpected authentication success during %s.",
 542             authctxt->method->name);
 543         return 0;
 544 }
 545
 546 /* ARGSUSED */
 547 int
 548 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 549 {
 550         Authctxt *authctxt = ctxt;
 551         char *authlist = NULL;
 552         int partial;
 553
 554         if (authctxt == NULL)
 555                 fatal("input_userauth_failure: no authentication context");
 556
 557         authlist = packet_get_string(NULL);
 558         partial = packet_get_char();
 559         packet_check_eom();
 560
 561         if (partial != 0) {
 562                 verbose("Authenticated with partial success.");
 563                 /* reset state */
 564                 pubkey_reset(authctxt);
 565         }
 566         debug("Authentications that can continue: %s", authlist);
 567
 568         userauth(authctxt, authlist);
 569         return 0;
 570 }
 571
 572 /* ARGSUSED */
 573 int
 574 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 575 {
 576         Authctxt *authctxt = ctxt;
 577         Key *key = NULL;
 578         Identity *id = NULL;
 579         Buffer b;
 580         int pktype, sent = 0;
 581         u_int alen, blen;
 582         char *pkalg, *fp;
 583         u_char *pkblob;
 584
 585         if (authctxt == NULL)
 586                 fatal("input_userauth_pk_ok: no authentication context");
 587         if (datafellows & SSH_BUG_PKOK) {
 588                 /* this is similar to SSH_BUG_PKAUTH */
 589                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 590                 pkblob = packet_get_string(&blen);
 591                 buffer_init(&b);
 592                 buffer_append(&b, pkblob, blen);
 593                 pkalg = buffer_get_string(&b, &alen);
 594                 buffer_free(&b);
 595         } else {
 596                 pkalg = packet_get_string(&alen);
 597                 pkblob = packet_get_string(&blen);
 598         }
 599         packet_check_eom();
 600
 601         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 602
 603         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 604                 debug("unknown pkalg %s", pkalg);
 605                 goto done;
 606         }
 607         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 608                 debug("no key from blob. pkalg %s", pkalg);
 609                 goto done;
 610         }
 611         if (key->type != pktype) {
 612                 error("input_userauth_pk_ok: type mismatch "
 613                     "for decoded key (received %d, expected %d)",
 614                     key->type, pktype);
 615                 goto done;
 616         }
 617         if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
 618             SSH_FP_DEFAULT)) == NULL)
 619                 goto done;
 620         debug2("input_userauth_pk_ok: fp %s", fp);
 621         free(fp);
 622
 623         /*
 624          * search keys in the reverse order, because last candidate has been
 625          * moved to the end of the queue.  this also avoids confusion by
 626          * duplicate keys
 627          */
 628         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 629                 if (key_equal(key, id->key)) {
 630                         sent = sign_and_send_pubkey(authctxt, id);
 631                         break;
 632                 }
 633         }
 634 done:
 635         if (key != NULL)
 636                 key_free(key);
 637         free(pkalg);
 638         free(pkblob);
 639
 640         /* try another method if we did not send a packet */
 641         if (sent == 0)
 642                 userauth(authctxt, NULL);
 643         return 0;
 644 }
 645
 646 #ifdef GSSAPI
 647 int
 648 userauth_gssapi(Authctxt *authctxt)
 649 {
 650         Gssctxt *gssctxt = NULL;
 651         static gss_OID_set gss_supported = NULL;
 652         static u_int mech = 0;
 653         OM_uint32 min;
 654         int ok = 0;
 655
 656         /* Try one GSSAPI method at a time, rather than sending them all at
 657          * once. */
 658
 659         if (gss_supported == NULL)
 660                 gss_indicate_mechs(&min, &gss_supported);
 661
 662         /* Check to see if the mechanism is usable before we offer it */
 663         while (mech < gss_supported->count && !ok) {
 664                 /* My DER encoding requires length<128 */
 665                 if (gss_supported->elements[mech].length < 128 &&
 666                     ssh_gssapi_check_mechanism(&gssctxt,
 667                     &gss_supported->elements[mech], authctxt->host)) {
 668                         ok = 1; /* Mechanism works */
 669                 } else {
 670                         mech++;
 671                 }
 672         }
 673
 674         if (!ok)
 675                 return 0;
 676
 677         authctxt->methoddata=(void *)gssctxt;
 678
 679         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 680         packet_put_cstring(authctxt->server_user);
 681         packet_put_cstring(authctxt->service);
 682         packet_put_cstring(authctxt->method->name);
 683
 684         packet_put_int(1);
 685
 686         packet_put_int((gss_supported->elements[mech].length) + 2);
 687         packet_put_char(SSH_GSS_OIDTYPE);
 688         packet_put_char(gss_supported->elements[mech].length);
 689         packet_put_raw(gss_supported->elements[mech].elements,
 690             gss_supported->elements[mech].length);
 691
 692         packet_send();
 693
 694         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 695         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 696         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 697         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 698
 699         mech++; /* Move along to next candidate */
 700
 701         return 1;
 702 }
 703
 704 static OM_uint32
 705 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 706 {
 707         Authctxt *authctxt = ctxt;
 708         Gssctxt *gssctxt = authctxt->methoddata;
 709         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 710         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 711         gss_buffer_desc gssbuf;
 712         OM_uint32 status, ms, flags;
 713         Buffer b;
 714
 715         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 716             recv_tok, &send_tok, &flags);
 717
 718         if (send_tok.length > 0) {
 719                 if (GSS_ERROR(status))
 720                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 721                 else
 722                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 723
 724                 packet_put_string(send_tok.value, send_tok.length);
 725                 packet_send();
 726                 gss_release_buffer(&ms, &send_tok);
 727         }
 728
 729         if (status == GSS_S_COMPLETE) {
 730                 /* send either complete or MIC, depending on mechanism */
 731                 if (!(flags & GSS_C_INTEG_FLAG)) {
 732                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 733                         packet_send();
 734                 } else {
 735                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 736                             authctxt->service, "gssapi-with-mic");
 737
 738                         gssbuf.value = buffer_ptr(&b);
 739                         gssbuf.length = buffer_len(&b);
 740
 741                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 742
 743                         if (!GSS_ERROR(status)) {
 744                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 745                                 packet_put_string(mic.value, mic.length);
 746
 747                                 packet_send();
 748                         }
 749
 750                         buffer_free(&b);
 751                         gss_release_buffer(&ms, &mic);
 752                 }
 753         }
 754
 755         return status;
 756 }
 757
 758 /* ARGSUSED */
 759 int
 760 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 761 {
 762         Authctxt *authctxt = ctxt;
 763         Gssctxt *gssctxt;
 764         int oidlen;
 765         char *oidv;
 766
 767         if (authctxt == NULL)
 768                 fatal("input_gssapi_response: no authentication context");
 769         gssctxt = authctxt->methoddata;
 770
 771         /* Setup our OID */
 772         oidv = packet_get_string(&oidlen);
 773
 774         if (oidlen <= 2 ||
 775             oidv[0] != SSH_GSS_OIDTYPE ||
 776             oidv[1] != oidlen - 2) {
 777                 free(oidv);
 778                 debug("Badly encoded mechanism OID received");
 779                 userauth(authctxt, NULL);
 780                 return 0;
 781         }
 782
 783         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 784                 fatal("Server returned different OID than expected");
 785
 786         packet_check_eom();
 787
 788         free(oidv);
 789
 790         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 791                 /* Start again with next method on list */
 792                 debug("Trying to start again");
 793                 userauth(authctxt, NULL);
 794                 return 0;
 795         }
 796         return 0;
 797 }
 798
 799 /* ARGSUSED */
 800 int
 801 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 802 {
 803         Authctxt *authctxt = ctxt;
 804         gss_buffer_desc recv_tok;
 805         OM_uint32 status;
 806         u_int slen;
 807
 808         if (authctxt == NULL)
 809                 fatal("input_gssapi_response: no authentication context");
 810
 811         recv_tok.value = packet_get_string(&slen);
 812         recv_tok.length = slen; /* safe typecast */
 813
 814         packet_check_eom();
 815
 816         status = process_gssapi_token(ctxt, &recv_tok);
 817
 818         free(recv_tok.value);
 819
 820         if (GSS_ERROR(status)) {
 821                 /* Start again with the next method in the list */
 822                 userauth(authctxt, NULL);
 823                 return 0;
 824         }
 825         return 0;
 826 }
 827
 828 /* ARGSUSED */
 829 int
 830 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 831 {
 832         Authctxt *authctxt = ctxt;
 833         Gssctxt *gssctxt;
 834         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 835         gss_buffer_desc recv_tok;
 836         OM_uint32 ms;
 837         u_int len;
 838
 839         if (authctxt == NULL)
 840                 fatal("input_gssapi_response: no authentication context");
 841         gssctxt = authctxt->methoddata;
 842
 843         recv_tok.value = packet_get_string(&len);
 844         recv_tok.length = len;
 845
 846         packet_check_eom();
 847
 848         /* Stick it into GSSAPI and see what it says */
 849         (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 850             &recv_tok, &send_tok, NULL);
 851
 852         free(recv_tok.value);
 853         gss_release_buffer(&ms, &send_tok);
 854
 855         /* Server will be returning a failed packet after this one */
 856         return 0;
 857 }
 858
 859 /* ARGSUSED */
 860 int
 861 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 862 {
 863         char *msg;
 864         char *lang;
 865
 866         /* maj */(void)packet_get_int();
 867         /* min */(void)packet_get_int();
 868         msg=packet_get_string(NULL);
 869         lang=packet_get_string(NULL);
 870
 871         packet_check_eom();
 872
 873         debug("Server GSSAPI Error:\n%s", msg);
 874         free(msg);
 875         free(lang);
 876         return 0;
 877 }
 878 #endif /* GSSAPI */
 879
 880 int
 881 userauth_none(Authctxt *authctxt)
 882 {
 883         /* initial userauth request */
 884         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 885         packet_put_cstring(authctxt->server_user);
 886         packet_put_cstring(authctxt->service);
 887         packet_put_cstring(authctxt->method->name);
 888         packet_send();
 889         return 1;
 890 }
 891
 892 int
 893 userauth_passwd(Authctxt *authctxt)
 894 {
 895         static int attempt = 0;
 896         char prompt[150];
 897         char *password;
 898         const char *host = options.host_key_alias ?  options.host_key_alias :
 899             authctxt->host;
 900
 901         if (attempt++ >= options.number_of_password_prompts)
 902                 return 0;
 903
 904         if (attempt != 1)
 905                 error("Permission denied, please try again.");
 906
 907         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 908             authctxt->server_user, host);
 909         password = read_passphrase(prompt, 0);
 910         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 911         packet_put_cstring(authctxt->server_user);
 912         packet_put_cstring(authctxt->service);
 913         packet_put_cstring(authctxt->method->name);
 914         packet_put_char(0);
 915         packet_put_cstring(password);
 916         explicit_bzero(password, strlen(password));
 917         free(password);
 918         packet_add_padding(64);
 919         packet_send();
 920
 921         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 922             &input_userauth_passwd_changereq);
 923
 924         return 1;
 925 }
 926
 927 /*
 928  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 929  */
 930 /* ARGSUSED */
 931 int
 932 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 933 {
 934         Authctxt *authctxt = ctxt;
 935         char *info, *lang, *password = NULL, *retype = NULL;
 936         char prompt[150];
 937         const char *host;
 938
 939         debug2("input_userauth_passwd_changereq");
 940
 941         if (authctxt == NULL)
 942                 fatal("input_userauth_passwd_changereq: "
 943                     "no authentication context");
 944         host = options.host_key_alias ? options.host_key_alias : authctxt->host;
 945
 946         info = packet_get_string(NULL);
 947         lang = packet_get_string(NULL);
 948         if (strlen(info) > 0)
 949                 logit("%s", info);
 950         free(info);
 951         free(lang);
 952         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 953         packet_put_cstring(authctxt->server_user);
 954         packet_put_cstring(authctxt->service);
 955         packet_put_cstring(authctxt->method->name);
 956         packet_put_char(1);                     /* additional info */
 957         snprintf(prompt, sizeof(prompt),
 958             "Enter %.30s@%.128s's old password: ",
 959             authctxt->server_user, host);
 960         password = read_passphrase(prompt, 0);
 961         packet_put_cstring(password);
 962         explicit_bzero(password, strlen(password));
 963         free(password);
 964         password = NULL;
 965         while (password == NULL) {
 966                 snprintf(prompt, sizeof(prompt),
 967                     "Enter %.30s@%.128s's new password: ",
 968                     authctxt->server_user, host);
 969                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 970                 if (password == NULL) {
 971                         /* bail out */
 972                         return 0;
 973                 }
 974                 snprintf(prompt, sizeof(prompt),
 975                     "Retype %.30s@%.128s's new password: ",
 976                     authctxt->server_user, host);
 977                 retype = read_passphrase(prompt, 0);
 978                 if (strcmp(password, retype) != 0) {
 979                         explicit_bzero(password, strlen(password));
 980                         free(password);
 981                         logit("Mismatch; try again, EOF to quit.");
 982                         password = NULL;
 983                 }
 984                 explicit_bzero(retype, strlen(retype));
 985                 free(retype);
 986         }
 987         packet_put_cstring(password);
 988         explicit_bzero(password, strlen(password));
 989         free(password);
 990         packet_add_padding(64);
 991         packet_send();
 992
 993         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 994             &input_userauth_passwd_changereq);
 995         return 0;
 996 }
 997
 998 static const char *
 999 key_sign_encode(const struct sshkey *key)
1000 {
1001         struct ssh *ssh = active_state;
1002
1003         if (key->type == KEY_RSA) {
1004                 switch (ssh->kex->rsa_sha2) {
1005                 case 256:
1006                         return "rsa-sha2-256";
1007                 case 512:
1008                         return "rsa-sha2-512";
1009                 }
1010         }
1011         return key_ssh_name(key);
1012 }
1013
1014 static int
1015 identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
1016     const u_char *data, size_t datalen, u_int compat)
1017 {
1018         Key *prv;
1019         int ret;
1020
1021         /* the agent supports this key */
1022         if (id->key != NULL && id->agent_fd != -1)
1023                 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp,
1024                     data, datalen, key_sign_encode(id->key), compat);
1025
1026         /*
1027          * we have already loaded the private key or
1028          * the private key is stored in external hardware
1029          */
1030         if (id->key != NULL &&
1031             (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT)))
1032                 return (sshkey_sign(id->key, sigp, lenp, data, datalen,
1033                     key_sign_encode(id->key), compat));
1034
1035         /* load the private key from the file */
1036         if ((prv = load_identity_file(id)) == NULL)
1037                 return SSH_ERR_KEY_NOT_FOUND;
1038         ret = sshkey_sign(prv, sigp, lenp, data, datalen,
1039             key_sign_encode(prv), compat);
1040         sshkey_free(prv);
1041         return (ret);
1042 }
1043
1044 static int
1045 id_filename_matches(Identity *id, Identity *private_id)
1046 {
1047         const char *suffixes[] = { ".pub", "-cert.pub", NULL };
1048         size_t len = strlen(id->filename), plen = strlen(private_id->filename);
1049         size_t i, slen;
1050
1051         if (strcmp(id->filename, private_id->filename) == 0)
1052                 return 1;
1053         for (i = 0; suffixes[i]; i++) {
1054                 slen = strlen(suffixes[i]);
1055                 if (len > slen && plen == len - slen &&
1056                     strcmp(id->filename + (len - slen), suffixes[i]) == 0 &&
1057                     memcmp(id->filename, private_id->filename, plen) == 0)
1058                         return 1;
1059         }
1060         return 0;
1061 }
1062
1063 static int
1064 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1065 {
1066         Buffer b;
1067         Identity *private_id;
1068         u_char *blob, *signature;
1069         size_t slen;
1070         u_int bloblen, skip = 0;
1071         int matched, ret = -1, have_sig = 1;
1072         char *fp;
1073
1074         if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
1075             SSH_FP_DEFAULT)) == NULL)
1076                 return 0;
1077         debug3("%s: %s %s", __func__, key_type(id->key), fp);
1078         free(fp);
1079
1080         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1081                 /* we cannot handle this key */
1082                 debug3("sign_and_send_pubkey: cannot handle key");
1083                 return 0;
1084         }
1085         /* data to be signed */
1086         buffer_init(&b);
1087         if (datafellows & SSH_OLD_SESSIONID) {
1088                 buffer_append(&b, session_id2, session_id2_len);
1089                 skip = session_id2_len;
1090         } else {
1091                 buffer_put_string(&b, session_id2, session_id2_len);
1092                 skip = buffer_len(&b);
1093         }
1094         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1095         buffer_put_cstring(&b, authctxt->server_user);
1096         buffer_put_cstring(&b,
1097             datafellows & SSH_BUG_PKSERVICE ?
1098             "ssh-userauth" :
1099             authctxt->service);
1100         if (datafellows & SSH_BUG_PKAUTH) {
1101                 buffer_put_char(&b, have_sig);
1102         } else {
1103                 buffer_put_cstring(&b, authctxt->method->name);
1104                 buffer_put_char(&b, have_sig);
1105                 buffer_put_cstring(&b, key_sign_encode(id->key));
1106         }
1107         buffer_put_string(&b, blob, bloblen);
1108
1109         /*
1110          * If the key is an certificate, try to find a matching private key
1111          * and use it to complete the signature.
1112          * If no such private key exists, fall back to trying the certificate
1113          * key itself in case it has a private half already loaded.
1114          */
1115         if (key_is_cert(id->key)) {
1116                 matched = 0;
1117                 TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1118                         if (sshkey_equal_public(id->key, private_id->key) &&
1119                             id->key->type != private_id->key->type) {
1120                                 id = private_id;
1121                                 matched = 1;
1122                                 break;
1123                         }
1124                 }
1125                 /*
1126                  * Exact key matches are preferred, but also allow
1127                  * filename matches for non-PKCS#11/agent keys that
1128                  * didn't load public keys. This supports the case
1129                  * of keeping just a private key file and public
1130                  * certificate on disk.
1131                  */
1132                 if (!matched && !id->isprivate && id->agent_fd == -1 &&
1133                     (id->key->flags & SSHKEY_FLAG_EXT) == 0) {
1134                         TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1135                                 if (private_id->key == NULL &&
1136                                     id_filename_matches(id, private_id)) {
1137                                         id = private_id;
1138                                         matched = 1;
1139                                         break;
1140                                 }
1141                         }
1142                 }
1143                 if (matched) {
1144                         debug2("%s: using private key \"%s\"%s for "
1145                             "certificate", __func__, id->filename,
1146                             id->agent_fd != -1 ? " from agent" : "");
1147                 } else {
1148                         debug("%s: no separate private key for certificate "
1149                             "\"%s\"", __func__, id->filename);
1150                 }
1151         }
1152
1153         /* generate signature */
1154         ret = identity_sign(id, &signature, &slen,
1155             buffer_ptr(&b), buffer_len(&b), datafellows);
1156         if (ret != 0) {
1157                 if (ret != SSH_ERR_KEY_NOT_FOUND)
1158                         error("%s: signing failed: %s", __func__, ssh_err(ret));
1159                 free(blob);
1160                 buffer_free(&b);
1161                 return 0;
1162         }
1163 #ifdef DEBUG_PK
1164         buffer_dump(&b);
1165 #endif
1166         if (datafellows & SSH_BUG_PKSERVICE) {
1167                 buffer_clear(&b);
1168                 buffer_append(&b, session_id2, session_id2_len);
1169                 skip = session_id2_len;
1170                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1171                 buffer_put_cstring(&b, authctxt->server_user);
1172                 buffer_put_cstring(&b, authctxt->service);
1173                 buffer_put_cstring(&b, authctxt->method->name);
1174                 buffer_put_char(&b, have_sig);
1175                 if (!(datafellows & SSH_BUG_PKAUTH))
1176                         buffer_put_cstring(&b, key_ssh_name(id->key));
1177                 buffer_put_string(&b, blob, bloblen);
1178         }
1179         free(blob);
1180
1181         /* append signature */
1182         buffer_put_string(&b, signature, slen);
1183         free(signature);
1184
1185         /* skip session id and packet type */
1186         if (buffer_len(&b) < skip + 1)
1187                 fatal("userauth_pubkey: internal error");
1188         buffer_consume(&b, skip + 1);
1189
1190         /* put remaining data from buffer into packet */
1191         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1192         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1193         buffer_free(&b);
1194         packet_send();
1195
1196         return 1;
1197 }
1198
1199 static int
1200 send_pubkey_test(Authctxt *authctxt, Identity *id)
1201 {
1202         u_char *blob;
1203         u_int bloblen, have_sig = 0;
1204
1205         debug3("send_pubkey_test");
1206
1207         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1208                 /* we cannot handle this key */
1209                 debug3("send_pubkey_test: cannot handle key");
1210                 return 0;
1211         }
1212         /* register callback for USERAUTH_PK_OK message */
1213         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1214
1215         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1216         packet_put_cstring(authctxt->server_user);
1217         packet_put_cstring(authctxt->service);
1218         packet_put_cstring(authctxt->method->name);
1219         packet_put_char(have_sig);
1220         if (!(datafellows & SSH_BUG_PKAUTH))
1221                 packet_put_cstring(key_sign_encode(id->key));
1222         packet_put_string(blob, bloblen);
1223         free(blob);
1224         packet_send();
1225         return 1;
1226 }
1227
1228 static Key *
1229 load_identity_file(Identity *id)
1230 {
1231         Key *private = NULL;
1232         char prompt[300], *passphrase, *comment;
1233         int r, perm_ok = 0, quit = 0, i;
1234         struct stat st;
1235
1236         if (stat(id->filename, &st) < 0) {
1237                 (id->userprovided ? logit : debug3)("no such identity: %s: %s",
1238                     id->filename, strerror(errno));
1239                 return NULL;
1240         }
1241         snprintf(prompt, sizeof prompt,
1242             "Enter passphrase for key '%.100s': ", id->filename);
1243         for (i = 0; i <= options.number_of_password_prompts; i++) {
1244                 if (i == 0)
1245                         passphrase = "";
1246                 else {
1247                         passphrase = read_passphrase(prompt, 0);
1248                         if (*passphrase == '\0') {
1249                                 debug2("no passphrase given, try next key");
1250                                 free(passphrase);
1251                                 break;
1252                         }
1253                 }
1254                 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename,
1255                     passphrase, &private, &comment, &perm_ok))) {
1256                 case 0:
1257                         break;
1258                 case SSH_ERR_KEY_WRONG_PASSPHRASE:
1259                         if (options.batch_mode) {
1260                                 quit = 1;
1261                                 break;
1262                         }
1263                         if (i != 0)
1264                                 debug2("bad passphrase given, try again...");
1265                         break;
1266                 case SSH_ERR_SYSTEM_ERROR:
1267                         if (errno == ENOENT) {
1268                                 debug2("Load key \"%s\": %s",
1269                                     id->filename, ssh_err(r));
1270                                 quit = 1;
1271                                 break;
1272                         }
1273                         /* FALLTHROUGH */
1274                 default:
1275                         error("Load key \"%s\": %s", id->filename, ssh_err(r));
1276                         quit = 1;
1277                         break;
1278                 }
1279                 if (!quit && private != NULL && id->agent_fd == -1 &&
1280                     !(id->key && id->isprivate))
1281                         maybe_add_key_to_agent(id->filename, private, comment,
1282                             passphrase);
1283                 if (i > 0) {
1284                         explicit_bzero(passphrase, strlen(passphrase));
1285                         free(passphrase);
1286                 }
1287                 free(comment);
1288                 if (private != NULL || quit)
1289                         break;
1290         }
1291         return private;
1292 }
1293
1294 /*
1295  * try keys in the following order:
1296  *      1. certificates listed in the config file
1297  *      2. other input certificates
1298  *      3. agent keys that are found in the config file
1299  *      4. other agent keys
1300  *      5. keys that are only listed in the config file
1301  */
1302 static void
1303 pubkey_prepare(Authctxt *authctxt)
1304 {
1305         struct identity *id, *id2, *tmp;
1306         struct idlist agent, files, *preferred;
1307         struct sshkey *key;
1308         int agent_fd = -1, i, r, found;
1309         size_t j;
1310         struct ssh_identitylist *idlist;
1311
1312         TAILQ_INIT(&agent);     /* keys from the agent */
1313         TAILQ_INIT(&files);     /* keys from the config file */
1314         preferred = &authctxt->keys;
1315         TAILQ_INIT(preferred);  /* preferred order of keys */
1316
1317         /* list of keys stored in the filesystem and PKCS#11 */
1318         for (i = 0; i < options.num_identity_files; i++) {
1319                 key = options.identity_keys[i];
1320                 if (key && key->type == KEY_RSA1)
1321                         continue;
1322                 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1323                         continue;
1324                 options.identity_keys[i] = NULL;
1325                 id = xcalloc(1, sizeof(*id));
1326                 id->agent_fd = -1;
1327                 id->key = key;
1328                 id->filename = xstrdup(options.identity_files[i]);
1329                 id->userprovided = options.identity_file_userprovided[i];
1330                 TAILQ_INSERT_TAIL(&files, id, next);
1331         }
1332         /* list of certificates specified by user */
1333         for (i = 0; i < options.num_certificate_files; i++) {
1334                 key = options.certificates[i];
1335                 if (!key_is_cert(key) || key->cert == NULL ||
1336                     key->cert->type != SSH2_CERT_TYPE_USER)
1337                         continue;
1338                 id = xcalloc(1, sizeof(*id));
1339                 id->agent_fd = -1;
1340                 id->key = key;
1341                 id->filename = xstrdup(options.certificate_files[i]);
1342                 id->userprovided = options.certificate_file_userprovided[i];
1343                 TAILQ_INSERT_TAIL(preferred, id, next);
1344         }
1345         /* list of keys supported by the agent */
1346         if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) {
1347                 if (r != SSH_ERR_AGENT_NOT_PRESENT)
1348                         debug("%s: ssh_get_authentication_socket: %s",
1349                             __func__, ssh_err(r));
1350         } else if ((r = ssh_fetch_identitylist(agent_fd, 2, &idlist)) != 0) {
1351                 if (r != SSH_ERR_AGENT_NO_IDENTITIES)
1352                         debug("%s: ssh_fetch_identitylist: %s",
1353                             __func__, ssh_err(r));
1354                 close(agent_fd);
1355         } else {
1356                 for (j = 0; j < idlist->nkeys; j++) {
1357                         found = 0;
1358                         TAILQ_FOREACH(id, &files, next) {
1359                                 /*
1360                                  * agent keys from the config file are
1361                                  * preferred
1362                                  */
1363                                 if (sshkey_equal(idlist->keys[j], id->key)) {
1364                                         TAILQ_REMOVE(&files, id, next);
1365                                         TAILQ_INSERT_TAIL(preferred, id, next);
1366                                         id->agent_fd = agent_fd;
1367                                         found = 1;
1368                                         break;
1369                                 }
1370                         }
1371                         if (!found && !options.identities_only) {
1372                                 id = xcalloc(1, sizeof(*id));
1373                                 /* XXX "steals" key/comment from idlist */
1374                                 id->key = idlist->keys[j];
1375                                 id->filename = idlist->comments[j];
1376                                 idlist->keys[j] = NULL;
1377                                 idlist->comments[j] = NULL;
1378                                 id->agent_fd = agent_fd;
1379                                 TAILQ_INSERT_TAIL(&agent, id, next);
1380                         }
1381                 }
1382                 ssh_free_identitylist(idlist);
1383                 /* append remaining agent keys */
1384                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1385                         TAILQ_REMOVE(&agent, id, next);
1386                         TAILQ_INSERT_TAIL(preferred, id, next);
1387                 }
1388                 authctxt->agent_fd = agent_fd;
1389         }
1390         /* Prefer PKCS11 keys that are explicitly listed */
1391         TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1392                 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0)
1393                         continue;
1394                 found = 0;
1395                 TAILQ_FOREACH(id2, &files, next) {
1396                         if (id2->key == NULL ||
1397                             (id2->key->flags & SSHKEY_FLAG_EXT) == 0)
1398                                 continue;
1399                         if (sshkey_equal(id->key, id2->key)) {
1400                                 TAILQ_REMOVE(&files, id, next);
1401                                 TAILQ_INSERT_TAIL(preferred, id, next);
1402                                 found = 1;
1403                                 break;
1404                         }
1405                 }
1406                 /* If IdentitiesOnly set and key not found then don't use it */
1407                 if (!found && options.identities_only) {
1408                         TAILQ_REMOVE(&files, id, next);
1409                         explicit_bzero(id, sizeof(*id));
1410                         free(id);
1411                 }
1412         }
1413         /* append remaining keys from the config file */
1414         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1415                 TAILQ_REMOVE(&files, id, next);
1416                 TAILQ_INSERT_TAIL(preferred, id, next);
1417         }
1418         /* finally, filter by PubkeyAcceptedKeyTypes */
1419         TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
1420                 if (id->key != NULL &&
1421                     match_pattern_list(sshkey_ssh_name(id->key),
1422                     options.pubkey_key_types, 0) != 1) {
1423                         debug("Skipping %s key %s - "
1424                             "not in PubkeyAcceptedKeyTypes",
1425                             sshkey_ssh_name(id->key), id->filename);
1426                         TAILQ_REMOVE(preferred, id, next);
1427                         sshkey_free(id->key);
1428                         free(id->filename);
1429                         memset(id, 0, sizeof(*id));
1430                         continue;
1431                 }
1432                 debug2("key: %s (%p)%s%s", id->filename, id->key,
1433                     id->userprovided ? ", explicit" : "",
1434                     id->agent_fd != -1 ? ", agent" : "");
1435         }
1436 }
1437
1438 static void
1439 pubkey_cleanup(Authctxt *authctxt)
1440 {
1441         Identity *id;
1442
1443         if (authctxt->agent_fd != -1)
1444                 ssh_close_authentication_socket(authctxt->agent_fd);
1445         for (id = TAILQ_FIRST(&authctxt->keys); id;
1446             id = TAILQ_FIRST(&authctxt->keys)) {
1447                 TAILQ_REMOVE(&authctxt->keys, id, next);
1448                 sshkey_free(id->key);
1449                 free(id->filename);
1450                 free(id);
1451         }
1452 }
1453
1454 static void
1455 pubkey_reset(Authctxt *authctxt)
1456 {
1457         Identity *id;
1458
1459         TAILQ_FOREACH(id, &authctxt->keys, next)
1460                 id->tried = 0;
1461 }
1462
1463 static int
1464 try_identity(Identity *id)
1465 {
1466         if (!id->key)
1467                 return (0);
1468         if (key_type_plain(id->key->type) == KEY_RSA &&
1469             (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1470                 debug("Skipped %s key %s for RSA/MD5 server",
1471                     key_type(id->key), id->filename);
1472                 return (0);
1473         }
1474         return (id->key->type != KEY_RSA1);
1475 }
1476
1477 int
1478 userauth_pubkey(Authctxt *authctxt)
1479 {
1480         Identity *id;
1481         int sent = 0;
1482
1483         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1484                 if (id->tried++)
1485                         return (0);
1486                 /* move key to the end of the queue */
1487                 TAILQ_REMOVE(&authctxt->keys, id, next);
1488                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1489                 /*
1490                  * send a test message if we have the public key. for
1491                  * encrypted keys we cannot do this and have to load the
1492                  * private key instead
1493                  */
1494                 if (id->key != NULL) {
1495                         if (try_identity(id)) {
1496                                 debug("Offering %s public key: %s",
1497                                     key_type(id->key), id->filename);
1498                                 sent = send_pubkey_test(authctxt, id);
1499                         }
1500                 } else {
1501                         debug("Trying private key: %s", id->filename);
1502                         id->key = load_identity_file(id);
1503                         if (id->key != NULL) {
1504                                 if (try_identity(id)) {
1505                                         id->isprivate = 1;
1506                                         sent = sign_and_send_pubkey(
1507                                             authctxt, id);
1508                                 }
1509                                 key_free(id->key);
1510                                 id->key = NULL;
1511                                 id->isprivate = 0;
1512                         }
1513                 }
1514                 if (sent)
1515                         return (sent);
1516         }
1517         return (0);
1518 }
1519
1520 /*
1521  * Send userauth request message specifying keyboard-interactive method.
1522  */
1523 int
1524 userauth_kbdint(Authctxt *authctxt)
1525 {
1526         static int attempt = 0;
1527
1528         if (attempt++ >= options.number_of_password_prompts)
1529                 return 0;
1530         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1531         if (attempt > 1 && !authctxt->info_req_seen) {
1532                 debug3("userauth_kbdint: disable: no info_req_seen");
1533                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1534                 return 0;
1535         }
1536
1537         debug2("userauth_kbdint");
1538         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1539         packet_put_cstring(authctxt->server_user);
1540         packet_put_cstring(authctxt->service);
1541         packet_put_cstring(authctxt->method->name);
1542         packet_put_cstring("");                                 /* lang */
1543         packet_put_cstring(options.kbd_interactive_devices ?
1544             options.kbd_interactive_devices : "");
1545         packet_send();
1546
1547         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1548         return 1;
1549 }
1550
1551 /*
1552  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1553  */
1554 int
1555 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1556 {
1557         Authctxt *authctxt = ctxt;
1558         char *name, *inst, *lang, *prompt, *response;
1559         u_int num_prompts, i;
1560         int echo = 0;
1561
1562         debug2("input_userauth_info_req");
1563
1564         if (authctxt == NULL)
1565                 fatal("input_userauth_info_req: no authentication context");
1566
1567         authctxt->info_req_seen = 1;
1568
1569         name = packet_get_string(NULL);
1570         inst = packet_get_string(NULL);
1571         lang = packet_get_string(NULL);
1572         if (strlen(name) > 0)
1573                 logit("%s", name);
1574         if (strlen(inst) > 0)
1575                 logit("%s", inst);
1576         free(name);
1577         free(inst);
1578         free(lang);
1579
1580         num_prompts = packet_get_int();
1581         /*
1582          * Begin to build info response packet based on prompts requested.
1583          * We commit to providing the correct number of responses, so if
1584          * further on we run into a problem that prevents this, we have to
1585          * be sure and clean this up and send a correct error response.
1586          */
1587         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1588         packet_put_int(num_prompts);
1589
1590         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1591         for (i = 0; i < num_prompts; i++) {
1592                 prompt = packet_get_string(NULL);
1593                 echo = packet_get_char();
1594
1595                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1596
1597                 packet_put_cstring(response);
1598                 explicit_bzero(response, strlen(response));
1599                 free(response);
1600                 free(prompt);
1601         }
1602         packet_check_eom(); /* done with parsing incoming message. */
1603
1604         packet_add_padding(64);
1605         packet_send();
1606         return 0;
1607 }
1608
1609 static int
1610 ssh_keysign(struct sshkey *key, u_char **sigp, size_t *lenp,
1611     const u_char *data, size_t datalen)
1612 {
1613         struct sshbuf *b;
1614         struct stat st;
1615         pid_t pid;
1616         int i, r, to[2], from[2], status, sock = packet_get_connection_in();
1617         u_char rversion = 0, version = 2;
1618         void (*osigchld)(int);
1619
1620         *sigp = NULL;
1621         *lenp = 0;
1622
1623         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1624                 error("%s: not installed: %s", __func__, strerror(errno));
1625                 return -1;
1626         }
1627         if (fflush(stdout) != 0) {
1628                 error("%s: fflush: %s", __func__, strerror(errno));
1629                 return -1;
1630         }
1631         if (pipe(to) < 0) {
1632                 error("%s: pipe: %s", __func__, strerror(errno));
1633                 return -1;
1634         }
1635         if (pipe(from) < 0) {
1636                 error("%s: pipe: %s", __func__, strerror(errno));
1637                 return -1;
1638         }
1639         if ((pid = fork()) < 0) {
1640                 error("%s: fork: %s", __func__, strerror(errno));
1641                 return -1;
1642         }
1643         osigchld = signal(SIGCHLD, SIG_DFL);
1644         if (pid == 0) {
1645                 /* keep the socket on exec */
1646                 fcntl(sock, F_SETFD, 0);
1647                 permanently_drop_suid(getuid());
1648                 close(from[0]);
1649                 if (dup2(from[1], STDOUT_FILENO) < 0)
1650                         fatal("%s: dup2: %s", __func__, strerror(errno));
1651                 close(to[1]);
1652                 if (dup2(to[0], STDIN_FILENO) < 0)
1653                         fatal("%s: dup2: %s", __func__, strerror(errno));
1654                 close(from[1]);
1655                 close(to[0]);
1656                 /* Close everything but stdio and the socket */
1657                 for (i = STDERR_FILENO + 1; i < sock; i++)
1658                         close(i);
1659                 closefrom(sock + 1);
1660                 debug3("%s: [child] pid=%ld, exec %s",
1661                     __func__, (long)getpid(), _PATH_SSH_KEY_SIGN);
1662                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL);
1663                 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN,
1664                     strerror(errno));
1665         }
1666         close(from[1]);
1667         close(to[0]);
1668
1669         if ((b = sshbuf_new()) == NULL)
1670                 fatal("%s: sshbuf_new failed", __func__);
1671         /* send # of sock, data to be signed */
1672         if ((r = sshbuf_put_u32(b, sock)) != 0 ||
1673             (r = sshbuf_put_string(b, data, datalen)) != 0)
1674                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1675         if (ssh_msg_send(to[1], version, b) == -1)
1676                 fatal("%s: couldn't send request", __func__);
1677         sshbuf_reset(b);
1678         r = ssh_msg_recv(from[0], b);
1679         close(from[0]);
1680         close(to[1]);
1681         if (r < 0) {
1682                 error("%s: no reply", __func__);
1683                 goto fail;
1684         }
1685
1686         errno = 0;
1687         while (waitpid(pid, &status, 0) < 0) {
1688                 if (errno != EINTR) {
1689                         error("%s: waitpid %ld: %s",
1690                             __func__, (long)pid, strerror(errno));
1691                         goto fail;
1692                 }
1693         }
1694         if (!WIFEXITED(status)) {
1695                 error("%s: exited abnormally", __func__);
1696                 goto fail;
1697         }
1698         if (WEXITSTATUS(status) != 0) {
1699                 error("%s: exited with status %d",
1700                     __func__, WEXITSTATUS(status));
1701                 goto fail;
1702         }
1703         if ((r = sshbuf_get_u8(b, &rversion)) != 0) {
1704                 error("%s: buffer error: %s", __func__, ssh_err(r));
1705                 goto fail;
1706         }
1707         if (rversion != version) {
1708                 error("%s: bad version", __func__);
1709                 goto fail;
1710         }
1711         if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) {
1712                 error("%s: buffer error: %s", __func__, ssh_err(r));
1713  fail:
1714                 signal(SIGCHLD, osigchld);
1715                 sshbuf_free(b);
1716                 return -1;
1717         }
1718         signal(SIGCHLD, osigchld);
1719         sshbuf_free(b);
1720
1721         return 0;
1722 }
1723
1724 int
1725 userauth_hostbased(Authctxt *authctxt)
1726 {
1727         struct ssh *ssh = active_state;
1728         struct sshkey *private = NULL;
1729         struct sshbuf *b = NULL;
1730         const char *service;
1731         u_char *sig = NULL, *keyblob = NULL;
1732         char *fp = NULL, *chost = NULL, *lname = NULL;
1733         size_t siglen = 0, keylen = 0;
1734         int i, r, success = 0;
1735
1736         if (authctxt->ktypes == NULL) {
1737                 authctxt->oktypes = xstrdup(options.hostbased_key_types);
1738                 authctxt->ktypes = authctxt->oktypes;
1739         }
1740
1741         /*
1742          * Work through each listed type pattern in HostbasedKeyTypes,
1743          * trying each hostkey that matches the type in turn.
1744          */
1745         for (;;) {
1746                 if (authctxt->active_ktype == NULL)
1747                         authctxt->active_ktype = strsep(&authctxt->ktypes, ",");
1748                 if (authctxt->active_ktype == NULL ||
1749                     *authctxt->active_ktype == '\0')
1750                         break;
1751                 debug3("%s: trying key type %s", __func__,
1752                     authctxt->active_ktype);
1753
1754                 /* check for a useful key */
1755                 private = NULL;
1756                 for (i = 0; i < authctxt->sensitive->nkeys; i++) {
1757                         if (authctxt->sensitive->keys[i] == NULL ||
1758                             authctxt->sensitive->keys[i]->type == KEY_RSA1 ||
1759                             authctxt->sensitive->keys[i]->type == KEY_UNSPEC)
1760                                 continue;
1761                         if (match_pattern_list(
1762                             sshkey_ssh_name(authctxt->sensitive->keys[i]),
1763                             authctxt->active_ktype, 0) != 1)
1764                                 continue;
1765                         /* we take and free the key */
1766                         private = authctxt->sensitive->keys[i];
1767                         authctxt->sensitive->keys[i] = NULL;
1768                         break;
1769                 }
1770                 /* Found one */
1771                 if (private != NULL)
1772                         break;
1773                 /* No more keys of this type; advance */
1774                 authctxt->active_ktype = NULL;
1775         }
1776         if (private == NULL) {
1777                 free(authctxt->oktypes);
1778                 authctxt->oktypes = authctxt->ktypes = NULL;
1779                 authctxt->active_ktype = NULL;
1780                 debug("No more client hostkeys for hostbased authentication.");
1781                 goto out;
1782         }
1783
1784         if ((fp = sshkey_fingerprint(private, options.fingerprint_hash,
1785             SSH_FP_DEFAULT)) == NULL) {
1786                 error("%s: sshkey_fingerprint failed", __func__);
1787                 goto out;
1788         }
1789         debug("%s: trying hostkey %s %s",
1790             __func__, sshkey_ssh_name(private), fp);
1791
1792         /* figure out a name for the client host */
1793         if ((lname = get_local_name(packet_get_connection_in())) == NULL) {
1794                 error("%s: cannot get local ipaddr/name", __func__);
1795                 goto out;
1796         }
1797
1798         /* XXX sshbuf_put_stringf? */
1799         xasprintf(&chost, "%s.", lname);
1800         debug2("%s: chost %s", __func__, chost);
1801
1802         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1803             authctxt->service;
1804
1805         /* construct data */
1806         if ((b = sshbuf_new()) == NULL) {
1807                 error("%s: sshbuf_new failed", __func__);
1808                 goto out;
1809         }
1810         if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) {
1811                 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r));
1812                 goto out;
1813         }
1814         if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 ||
1815             (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1816             (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
1817             (r = sshbuf_put_cstring(b, service)) != 0 ||
1818             (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
1819             (r = sshbuf_put_cstring(b, key_ssh_name(private))) != 0 ||
1820             (r = sshbuf_put_string(b, keyblob, keylen)) != 0 ||
1821             (r = sshbuf_put_cstring(b, chost)) != 0 ||
1822             (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) {
1823                 error("%s: buffer error: %s", __func__, ssh_err(r));
1824                 goto out;
1825         }
1826
1827 #ifdef DEBUG_PK
1828         sshbuf_dump(b, stderr);
1829 #endif
1830         if (authctxt->sensitive->external_keysign)
1831                 r = ssh_keysign(private, &sig, &siglen,
1832                     sshbuf_ptr(b), sshbuf_len(b));
1833         else if ((r = sshkey_sign(private, &sig, &siglen,
1834             sshbuf_ptr(b), sshbuf_len(b), NULL, datafellows)) != 0)
1835                 debug("%s: sshkey_sign: %s", __func__, ssh_err(r));
1836         if (r != 0) {
1837                 error("sign using hostkey %s %s failed",
1838                     sshkey_ssh_name(private), fp);
1839                 goto out;
1840         }
1841         if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1842             (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1843             (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1844             (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1845             (r = sshpkt_put_cstring(ssh, key_ssh_name(private))) != 0 ||
1846             (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 ||
1847             (r = sshpkt_put_cstring(ssh, chost)) != 0 ||
1848             (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 ||
1849             (r = sshpkt_put_string(ssh, sig, siglen)) != 0 ||
1850             (r = sshpkt_send(ssh)) != 0) {
1851                 error("%s: packet error: %s", __func__, ssh_err(r));
1852                 goto out;
1853         }
1854         success = 1;
1855
1856  out:
1857         if (sig != NULL) {
1858                 explicit_bzero(sig, siglen);
1859                 free(sig);
1860         }
1861         free(keyblob);
1862         free(lname);
1863         free(fp);
1864         free(chost);
1865         sshkey_free(private);
1866         sshbuf_free(b);
1867
1868         return success;
1869 }
1870
1871 /* find auth method */
1872
1873 /*
1874  * given auth method name, if configurable options permit this method fill
1875  * in auth_ident field and return true, otherwise return false.
1876  */
1877 static int
1878 authmethod_is_enabled(Authmethod *method)
1879 {
1880         if (method == NULL)
1881                 return 0;
1882         /* return false if options indicate this method is disabled */
1883         if  (method->enabled == NULL || *method->enabled == 0)
1884                 return 0;
1885         /* return false if batch mode is enabled but method needs interactive mode */
1886         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1887                 return 0;
1888         return 1;
1889 }
1890
1891 static Authmethod *
1892 authmethod_lookup(const char *name)
1893 {
1894         Authmethod *method = NULL;
1895         if (name != NULL)
1896                 for (method = authmethods; method->name != NULL; method++)
1897                         if (strcmp(name, method->name) == 0)
1898                                 return method;
1899         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1900         return NULL;
1901 }
1902
1903 /* XXX internal state */
1904 static Authmethod *current = NULL;
1905 static char *supported = NULL;
1906 static char *preferred = NULL;
1907
1908 /*
1909  * Given the authentication method list sent by the server, return the
1910  * next method we should try.  If the server initially sends a nil list,
1911  * use a built-in default list.
1912  */
1913 static Authmethod *
1914 authmethod_get(char *authlist)
1915 {
1916         char *name = NULL;
1917         u_int next;
1918
1919         /* Use a suitable default if we're passed a nil list.  */
1920         if (authlist == NULL || strlen(authlist) == 0)
1921                 authlist = options.preferred_authentications;
1922
1923         if (supported == NULL || strcmp(authlist, supported) != 0) {
1924                 debug3("start over, passed a different list %s", authlist);
1925                 free(supported);
1926                 supported = xstrdup(authlist);
1927                 preferred = options.preferred_authentications;
1928                 debug3("preferred %s", preferred);
1929                 current = NULL;
1930         } else if (current != NULL && authmethod_is_enabled(current))
1931                 return current;
1932
1933         for (;;) {
1934                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1935                         debug("No more authentication methods to try.");
1936                         current = NULL;
1937                         return NULL;
1938                 }
1939                 preferred += next;
1940                 debug3("authmethod_lookup %s", name);
1941                 debug3("remaining preferred: %s", preferred);
1942                 if ((current = authmethod_lookup(name)) != NULL &&
1943                     authmethod_is_enabled(current)) {
1944                         debug3("authmethod_is_enabled %s", name);
1945                         debug("Next authentication method: %s", name);
1946                         free(name);
1947                         return current;
1948                 }
1949                 free(name);
1950         }
1951 }
1952
1953 static char *
1954 authmethods_get(void)
1955 {
1956         Authmethod *method = NULL;
1957         Buffer b;
1958         char *list;
1959
1960         buffer_init(&b);
1961         for (method = authmethods; method->name != NULL; method++) {
1962                 if (authmethod_is_enabled(method)) {
1963                         if (buffer_len(&b) > 0)
1964                                 buffer_append(&b, ",", 1);
1965                         buffer_append(&b, method->name, strlen(method->name));
1966                 }
1967         }
1968         if ((list = sshbuf_dup_string(&b)) == NULL)
1969                 fatal("%s: sshbuf_dup_string failed", __func__);
1970         buffer_free(&b);
1971         return list;
1972 }
1973