crypto/openssh/sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.266 2017/08/27 00:38:41 dtucker Exp $ */
   2 /*
   3  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   4  * Copyright (c) 2008 Damien Miller.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include "includes.h"
  28
  29 #include <sys/types.h>
  30 #include <sys/socket.h>
  31 #include <sys/wait.h>
  32 #include <sys/stat.h>
  33
  34 #include <errno.h>
  35 #include <fcntl.h>
  36 #include <netdb.h>
  37 #include <pwd.h>
  38 #include <signal.h>
  39 #include <stdarg.h>
  40 #include <stdio.h>
  41 #include <string.h>
  42 #include <unistd.h>
  43 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !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(struct sshkey *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         ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done);
 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, struct ssh *);
 291 int     input_userauth_ext_info(int, u_int32_t, struct ssh *);
 292 int     input_userauth_success(int, u_int32_t, struct ssh *);
 293 int     input_userauth_success_unexpected(int, u_int32_t, struct ssh *);
 294 int     input_userauth_failure(int, u_int32_t, struct ssh *);
 295 int     input_userauth_banner(int, u_int32_t, struct ssh *);
 296 int     input_userauth_error(int, u_int32_t, struct ssh *);
 297 int     input_userauth_info_req(int, u_int32_t, struct ssh *);
 298 int     input_userauth_pk_ok(int, u_int32_t, struct ssh *);
 299 int     input_userauth_passwd_changereq(int, u_int32_t, struct ssh *);
 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, struct ssh *);
 310 int     input_gssapi_token(int type, u_int32_t, struct ssh *);
 311 int     input_gssapi_hash(int type, u_int32_t, struct ssh *);
 312 int     input_gssapi_error(int, u_int32_t, struct ssh *);
 313 int     input_gssapi_errtok(int, u_int32_t, struct ssh *);
 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 struct sshkey *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->authctxt = &authctxt;
 401         ssh_dispatch_init(ssh, &input_userauth_error);
 402         ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info);
 403         ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept);
 404         ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */
 405         ssh->authctxt = NULL;
 406
 407         pubkey_cleanup(&authctxt);
 408         ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 409
 410         if (!authctxt.success)
 411                 fatal("Authentication failed.");
 412         debug("Authentication succeeded (%s).", authctxt.method->name);
 413 }
 414
 415 /* ARGSUSED */
 416 int
 417 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh)
 418 {
 419         Authctxt *authctxt = ssh->authctxt;
 420         int r;
 421
 422         if (ssh_packet_remaining(ssh) > 0) {
 423                 char *reply;
 424
 425                 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0)
 426                         goto out;
 427                 debug2("service_accept: %s", reply);
 428                 free(reply);
 429         } else {
 430                 debug2("buggy server: service_accept w/o service");
 431         }
 432         if ((r = sshpkt_get_end(ssh)) != 0)
 433                 goto out;
 434         debug("SSH2_MSG_SERVICE_ACCEPT received");
 435
 436         /* initial userauth request */
 437         userauth_none(authctxt);
 438
 439         ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error);
 440         ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 441         ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 442         ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 443         r = 0;
 444  out:
 445         return r;
 446 }
 447
 448 /* ARGSUSED */
 449 int
 450 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh)
 451 {
 452         return kex_input_ext_info(type, seqnr, ssh);
 453 }
 454
 455 void
 456 userauth(Authctxt *authctxt, char *authlist)
 457 {
 458         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 459                 authctxt->method->cleanup(authctxt);
 460
 461         free(authctxt->methoddata);
 462         authctxt->methoddata = NULL;
 463         if (authlist == NULL) {
 464                 authlist = authctxt->authlist;
 465         } else {
 466                 free(authctxt->authlist);
 467                 authctxt->authlist = authlist;
 468         }
 469         for (;;) {
 470                 Authmethod *method = authmethod_get(authlist);
 471                 if (method == NULL)
 472                         fatal("%s@%s: Permission denied (%s).",
 473                             authctxt->server_user, authctxt->host, authlist);
 474                 authctxt->method = method;
 475
 476                 /* reset the per method handler */
 477                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 478                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 479
 480                 /* and try new method */
 481                 if (method->userauth(authctxt) != 0) {
 482                         debug2("we sent a %s packet, wait for reply", method->name);
 483                         break;
 484                 } else {
 485                         debug2("we did not send a packet, disable method");
 486                         method->enabled = NULL;
 487                 }
 488         }
 489 }
 490
 491 /* ARGSUSED */
 492 int
 493 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh)
 494 {
 495         fatal("input_userauth_error: bad message during authentication: "
 496             "type %d", type);
 497         return 0;
 498 }
 499
 500 /* ARGSUSED */
 501 int
 502 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh)
 503 {
 504         char *msg, *lang;
 505         u_int len;
 506
 507         debug3("%s", __func__);
 508         msg = packet_get_string(&len);
 509         lang = packet_get_string(NULL);
 510         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO)
 511                 fmprintf(stderr, "%s", msg);
 512         free(msg);
 513         free(lang);
 514         return 0;
 515 }
 516
 517 /* ARGSUSED */
 518 int
 519 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh)
 520 {
 521         Authctxt *authctxt = ssh->authctxt;
 522
 523         if (authctxt == NULL)
 524                 fatal("input_userauth_success: no authentication context");
 525         free(authctxt->authlist);
 526         authctxt->authlist = NULL;
 527         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 528                 authctxt->method->cleanup(authctxt);
 529         free(authctxt->methoddata);
 530         authctxt->methoddata = NULL;
 531         authctxt->success = 1;                  /* break out */
 532         return 0;
 533 }
 534
 535 int
 536 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh)
 537 {
 538         Authctxt *authctxt = ssh->authctxt;
 539
 540         if (authctxt == NULL)
 541                 fatal("%s: no authentication context", __func__);
 542
 543         fatal("Unexpected authentication success during %s.",
 544             authctxt->method->name);
 545         return 0;
 546 }
 547
 548 /* ARGSUSED */
 549 int
 550 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh)
 551 {
 552         Authctxt *authctxt = ssh->authctxt;
 553         char *authlist = NULL;
 554         int partial;
 555
 556         if (authctxt == NULL)
 557                 fatal("input_userauth_failure: no authentication context");
 558
 559         authlist = packet_get_string(NULL);
 560         partial = packet_get_char();
 561         packet_check_eom();
 562
 563         if (partial != 0) {
 564                 verbose("Authenticated with partial success.");
 565                 /* reset state */
 566                 pubkey_reset(authctxt);
 567         }
 568         debug("Authentications that can continue: %s", authlist);
 569
 570         userauth(authctxt, authlist);
 571         return 0;
 572 }
 573
 574 /* ARGSUSED */
 575 int
 576 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh)
 577 {
 578         Authctxt *authctxt = ssh->authctxt;
 579         struct sshkey *key = NULL;
 580         Identity *id = NULL;
 581         Buffer b;
 582         int pktype, sent = 0;
 583         u_int alen, blen;
 584         char *pkalg, *fp;
 585         u_char *pkblob;
 586
 587         if (authctxt == NULL)
 588                 fatal("input_userauth_pk_ok: no authentication context");
 589         if (datafellows & SSH_BUG_PKOK) {
 590                 /* this is similar to SSH_BUG_PKAUTH */
 591                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 592                 pkblob = packet_get_string(&blen);
 593                 buffer_init(&b);
 594                 buffer_append(&b, pkblob, blen);
 595                 pkalg = buffer_get_string(&b, &alen);
 596                 buffer_free(&b);
 597         } else {
 598                 pkalg = packet_get_string(&alen);
 599                 pkblob = packet_get_string(&blen);
 600         }
 601         packet_check_eom();
 602
 603         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 604
 605         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 606                 debug("unknown pkalg %s", pkalg);
 607                 goto done;
 608         }
 609         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 610                 debug("no key from blob. pkalg %s", pkalg);
 611                 goto done;
 612         }
 613         if (key->type != pktype) {
 614                 error("input_userauth_pk_ok: type mismatch "
 615                     "for decoded key (received %d, expected %d)",
 616                     key->type, pktype);
 617                 goto done;
 618         }
 619         if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
 620             SSH_FP_DEFAULT)) == NULL)
 621                 goto done;
 622         debug2("input_userauth_pk_ok: fp %s", fp);
 623         free(fp);
 624
 625         /*
 626          * search keys in the reverse order, because last candidate has been
 627          * moved to the end of the queue.  this also avoids confusion by
 628          * duplicate keys
 629          */
 630         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 631                 if (key_equal(key, id->key)) {
 632                         sent = sign_and_send_pubkey(authctxt, id);
 633                         break;
 634                 }
 635         }
 636 done:
 637         if (key != NULL)
 638                 key_free(key);
 639         free(pkalg);
 640         free(pkblob);
 641
 642         /* try another method if we did not send a packet */
 643         if (sent == 0)
 644                 userauth(authctxt, NULL);
 645         return 0;
 646 }
 647
 648 #ifdef GSSAPI
 649 int
 650 userauth_gssapi(Authctxt *authctxt)
 651 {
 652         Gssctxt *gssctxt = NULL;
 653         static gss_OID_set gss_supported = NULL;
 654         static u_int mech = 0;
 655         OM_uint32 min;
 656         int ok = 0;
 657
 658         /* Try one GSSAPI method at a time, rather than sending them all at
 659          * once. */
 660
 661         if (gss_supported == NULL)
 662                 gss_indicate_mechs(&min, &gss_supported);
 663
 664         /* Check to see if the mechanism is usable before we offer it */
 665         while (mech < gss_supported->count && !ok) {
 666                 /* My DER encoding requires length<128 */
 667                 if (gss_supported->elements[mech].length < 128 &&
 668                     ssh_gssapi_check_mechanism(&gssctxt,
 669                     &gss_supported->elements[mech], authctxt->host)) {
 670                         ok = 1; /* Mechanism works */
 671                 } else {
 672                         mech++;
 673                 }
 674         }
 675
 676         if (!ok)
 677                 return 0;
 678
 679         authctxt->methoddata=(void *)gssctxt;
 680
 681         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 682         packet_put_cstring(authctxt->server_user);
 683         packet_put_cstring(authctxt->service);
 684         packet_put_cstring(authctxt->method->name);
 685
 686         packet_put_int(1);
 687
 688         packet_put_int((gss_supported->elements[mech].length) + 2);
 689         packet_put_char(SSH_GSS_OIDTYPE);
 690         packet_put_char(gss_supported->elements[mech].length);
 691         packet_put_raw(gss_supported->elements[mech].elements,
 692             gss_supported->elements[mech].length);
 693
 694         packet_send();
 695
 696         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 697         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 698         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 699         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 700
 701         mech++; /* Move along to next candidate */
 702
 703         return 1;
 704 }
 705
 706 static OM_uint32
 707 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok)
 708 {
 709         Authctxt *authctxt = ssh->authctxt;
 710         Gssctxt *gssctxt = authctxt->methoddata;
 711         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 712         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 713         gss_buffer_desc gssbuf;
 714         OM_uint32 status, ms, flags;
 715         Buffer b;
 716
 717         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 718             recv_tok, &send_tok, &flags);
 719
 720         if (send_tok.length > 0) {
 721                 if (GSS_ERROR(status))
 722                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 723                 else
 724                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 725
 726                 packet_put_string(send_tok.value, send_tok.length);
 727                 packet_send();
 728                 gss_release_buffer(&ms, &send_tok);
 729         }
 730
 731         if (status == GSS_S_COMPLETE) {
 732                 /* send either complete or MIC, depending on mechanism */
 733                 if (!(flags & GSS_C_INTEG_FLAG)) {
 734                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 735                         packet_send();
 736                 } else {
 737                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 738                             authctxt->service, "gssapi-with-mic");
 739
 740                         gssbuf.value = buffer_ptr(&b);
 741                         gssbuf.length = buffer_len(&b);
 742
 743                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 744
 745                         if (!GSS_ERROR(status)) {
 746                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 747                                 packet_put_string(mic.value, mic.length);
 748
 749                                 packet_send();
 750                         }
 751
 752                         buffer_free(&b);
 753                         gss_release_buffer(&ms, &mic);
 754                 }
 755         }
 756
 757         return status;
 758 }
 759
 760 /* ARGSUSED */
 761 int
 762 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh)
 763 {
 764         Authctxt *authctxt = ssh->authctxt;
 765         Gssctxt *gssctxt;
 766         int oidlen;
 767         char *oidv;
 768
 769         if (authctxt == NULL)
 770                 fatal("input_gssapi_response: no authentication context");
 771         gssctxt = authctxt->methoddata;
 772
 773         /* Setup our OID */
 774         oidv = packet_get_string(&oidlen);
 775
 776         if (oidlen <= 2 ||
 777             oidv[0] != SSH_GSS_OIDTYPE ||
 778             oidv[1] != oidlen - 2) {
 779                 free(oidv);
 780                 debug("Badly encoded mechanism OID received");
 781                 userauth(authctxt, NULL);
 782                 return 0;
 783         }
 784
 785         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 786                 fatal("Server returned different OID than expected");
 787
 788         packet_check_eom();
 789
 790         free(oidv);
 791
 792         if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) {
 793                 /* Start again with next method on list */
 794                 debug("Trying to start again");
 795                 userauth(authctxt, NULL);
 796                 return 0;
 797         }
 798         return 0;
 799 }
 800
 801 /* ARGSUSED */
 802 int
 803 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh)
 804 {
 805         Authctxt *authctxt = ssh->authctxt;
 806         gss_buffer_desc recv_tok;
 807         OM_uint32 status;
 808         u_int slen;
 809
 810         if (authctxt == NULL)
 811                 fatal("input_gssapi_response: no authentication context");
 812
 813         recv_tok.value = packet_get_string(&slen);
 814         recv_tok.length = slen; /* safe typecast */
 815
 816         packet_check_eom();
 817
 818         status = process_gssapi_token(ssh, &recv_tok);
 819
 820         free(recv_tok.value);
 821
 822         if (GSS_ERROR(status)) {
 823                 /* Start again with the next method in the list */
 824                 userauth(authctxt, NULL);
 825                 return 0;
 826         }
 827         return 0;
 828 }
 829
 830 /* ARGSUSED */
 831 int
 832 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh)
 833 {
 834         Authctxt *authctxt = ssh->authctxt;
 835         Gssctxt *gssctxt;
 836         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 837         gss_buffer_desc recv_tok;
 838         OM_uint32 ms;
 839         u_int len;
 840
 841         if (authctxt == NULL)
 842                 fatal("input_gssapi_response: no authentication context");
 843         gssctxt = authctxt->methoddata;
 844
 845         recv_tok.value = packet_get_string(&len);
 846         recv_tok.length = len;
 847
 848         packet_check_eom();
 849
 850         /* Stick it into GSSAPI and see what it says */
 851         (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 852             &recv_tok, &send_tok, NULL);
 853
 854         free(recv_tok.value);
 855         gss_release_buffer(&ms, &send_tok);
 856
 857         /* Server will be returning a failed packet after this one */
 858         return 0;
 859 }
 860
 861 /* ARGSUSED */
 862 int
 863 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh)
 864 {
 865         char *msg;
 866         char *lang;
 867
 868         /* maj */(void)packet_get_int();
 869         /* min */(void)packet_get_int();
 870         msg=packet_get_string(NULL);
 871         lang=packet_get_string(NULL);
 872
 873         packet_check_eom();
 874
 875         debug("Server GSSAPI Error:\n%s", msg);
 876         free(msg);
 877         free(lang);
 878         return 0;
 879 }
 880 #endif /* GSSAPI */
 881
 882 int
 883 userauth_none(Authctxt *authctxt)
 884 {
 885         /* initial userauth request */
 886         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 887         packet_put_cstring(authctxt->server_user);
 888         packet_put_cstring(authctxt->service);
 889         packet_put_cstring(authctxt->method->name);
 890         packet_send();
 891         return 1;
 892 }
 893
 894 int
 895 userauth_passwd(Authctxt *authctxt)
 896 {
 897         static int attempt = 0;
 898         char prompt[256];
 899         char *password;
 900         const char *host = options.host_key_alias ?  options.host_key_alias :
 901             authctxt->host;
 902
 903         if (attempt++ >= options.number_of_password_prompts)
 904                 return 0;
 905
 906         if (attempt != 1)
 907                 error("Permission denied, please try again.");
 908
 909         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 910             authctxt->server_user, host);
 911         password = read_passphrase(prompt, 0);
 912         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 913         packet_put_cstring(authctxt->server_user);
 914         packet_put_cstring(authctxt->service);
 915         packet_put_cstring(authctxt->method->name);
 916         packet_put_char(0);
 917         packet_put_cstring(password);
 918         explicit_bzero(password, strlen(password));
 919         free(password);
 920         packet_add_padding(64);
 921         packet_send();
 922
 923         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 924             &input_userauth_passwd_changereq);
 925
 926         return 1;
 927 }
 928
 929 /*
 930  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 931  */
 932 /* ARGSUSED */
 933 int
 934 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh)
 935 {
 936         Authctxt *authctxt = ssh->authctxt;
 937         char *info, *lang, *password = NULL, *retype = NULL;
 938         char prompt[256];
 939         const char *host;
 940
 941         debug2("input_userauth_passwd_changereq");
 942
 943         if (authctxt == NULL)
 944                 fatal("input_userauth_passwd_changereq: "
 945                     "no authentication context");
 946         host = options.host_key_alias ? options.host_key_alias : authctxt->host;
 947
 948         info = packet_get_string(NULL);
 949         lang = packet_get_string(NULL);
 950         if (strlen(info) > 0)
 951                 logit("%s", info);
 952         free(info);
 953         free(lang);
 954         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 955         packet_put_cstring(authctxt->server_user);
 956         packet_put_cstring(authctxt->service);
 957         packet_put_cstring(authctxt->method->name);
 958         packet_put_char(1);                     /* additional info */
 959         snprintf(prompt, sizeof(prompt),
 960             "Enter %.30s@%.128s's old password: ",
 961             authctxt->server_user, host);
 962         password = read_passphrase(prompt, 0);
 963         packet_put_cstring(password);
 964         explicit_bzero(password, strlen(password));
 965         free(password);
 966         password = NULL;
 967         while (password == NULL) {
 968                 snprintf(prompt, sizeof(prompt),
 969                     "Enter %.30s@%.128s's new password: ",
 970                     authctxt->server_user, host);
 971                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 972                 if (password == NULL) {
 973                         /* bail out */
 974                         return 0;
 975                 }
 976                 snprintf(prompt, sizeof(prompt),
 977                     "Retype %.30s@%.128s's new password: ",
 978                     authctxt->server_user, host);
 979                 retype = read_passphrase(prompt, 0);
 980                 if (strcmp(password, retype) != 0) {
 981                         explicit_bzero(password, strlen(password));
 982                         free(password);
 983                         logit("Mismatch; try again, EOF to quit.");
 984                         password = NULL;
 985                 }
 986                 explicit_bzero(retype, strlen(retype));
 987                 free(retype);
 988         }
 989         packet_put_cstring(password);
 990         explicit_bzero(password, strlen(password));
 991         free(password);
 992         packet_add_padding(64);
 993         packet_send();
 994
 995         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 996             &input_userauth_passwd_changereq);
 997         return 0;
 998 }
 999
1000 static const char *
1001 key_sign_encode(const struct sshkey *key)
1002 {
1003         struct ssh *ssh = active_state;
1004
1005         if (key->type == KEY_RSA) {
1006                 switch (ssh->kex->rsa_sha2) {
1007                 case 256:
1008                         return "rsa-sha2-256";
1009                 case 512:
1010                         return "rsa-sha2-512";
1011                 }
1012         }
1013         return key_ssh_name(key);
1014 }
1015
1016 static int
1017 identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
1018     const u_char *data, size_t datalen, u_int compat)
1019 {
1020         struct sshkey *prv;
1021         int ret;
1022
1023         /* the agent supports this key */
1024         if (id->key != NULL && id->agent_fd != -1)
1025                 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp,
1026                     data, datalen, key_sign_encode(id->key), compat);
1027
1028         /*
1029          * we have already loaded the private key or
1030          * the private key is stored in external hardware
1031          */
1032         if (id->key != NULL &&
1033             (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT)))
1034                 return (sshkey_sign(id->key, sigp, lenp, data, datalen,
1035                     key_sign_encode(id->key), compat));
1036
1037         /* load the private key from the file */
1038         if ((prv = load_identity_file(id)) == NULL)
1039                 return SSH_ERR_KEY_NOT_FOUND;
1040         if (id->key != NULL && !sshkey_equal_public(prv, id->key)) {
1041                 error("%s: private key %s contents do not match public",
1042                    __func__, id->filename);
1043                 return SSH_ERR_KEY_NOT_FOUND;
1044         }
1045         ret = sshkey_sign(prv, sigp, lenp, data, datalen,
1046             key_sign_encode(prv), compat);
1047         sshkey_free(prv);
1048         return (ret);
1049 }
1050
1051 static int
1052 id_filename_matches(Identity *id, Identity *private_id)
1053 {
1054         const char *suffixes[] = { ".pub", "-cert.pub", NULL };
1055         size_t len = strlen(id->filename), plen = strlen(private_id->filename);
1056         size_t i, slen;
1057
1058         if (strcmp(id->filename, private_id->filename) == 0)
1059                 return 1;
1060         for (i = 0; suffixes[i]; i++) {
1061                 slen = strlen(suffixes[i]);
1062                 if (len > slen && plen == len - slen &&
1063                     strcmp(id->filename + (len - slen), suffixes[i]) == 0 &&
1064                     memcmp(id->filename, private_id->filename, plen) == 0)
1065                         return 1;
1066         }
1067         return 0;
1068 }
1069
1070 static int
1071 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1072 {
1073         Buffer b;
1074         Identity *private_id;
1075         u_char *blob, *signature;
1076         size_t slen;
1077         u_int bloblen, skip = 0;
1078         int matched, ret = -1, have_sig = 1;
1079         char *fp;
1080
1081         if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
1082             SSH_FP_DEFAULT)) == NULL)
1083                 return 0;
1084         debug3("%s: %s %s", __func__, key_type(id->key), fp);
1085         free(fp);
1086
1087         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1088                 /* we cannot handle this key */
1089                 debug3("sign_and_send_pubkey: cannot handle key");
1090                 return 0;
1091         }
1092         /* data to be signed */
1093         buffer_init(&b);
1094         if (datafellows & SSH_OLD_SESSIONID) {
1095                 buffer_append(&b, session_id2, session_id2_len);
1096                 skip = session_id2_len;
1097         } else {
1098                 buffer_put_string(&b, session_id2, session_id2_len);
1099                 skip = buffer_len(&b);
1100         }
1101         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1102         buffer_put_cstring(&b, authctxt->server_user);
1103         buffer_put_cstring(&b,
1104             datafellows & SSH_BUG_PKSERVICE ?
1105             "ssh-userauth" :
1106             authctxt->service);
1107         if (datafellows & SSH_BUG_PKAUTH) {
1108                 buffer_put_char(&b, have_sig);
1109         } else {
1110                 buffer_put_cstring(&b, authctxt->method->name);
1111                 buffer_put_char(&b, have_sig);
1112                 buffer_put_cstring(&b, key_sign_encode(id->key));
1113         }
1114         buffer_put_string(&b, blob, bloblen);
1115
1116         /*
1117          * If the key is an certificate, try to find a matching private key
1118          * and use it to complete the signature.
1119          * If no such private key exists, fall back to trying the certificate
1120          * key itself in case it has a private half already loaded.
1121          */
1122         if (key_is_cert(id->key)) {
1123                 matched = 0;
1124                 TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1125                         if (sshkey_equal_public(id->key, private_id->key) &&
1126                             id->key->type != private_id->key->type) {
1127                                 id = private_id;
1128                                 matched = 1;
1129                                 break;
1130                         }
1131                 }
1132                 /*
1133                  * Exact key matches are preferred, but also allow
1134                  * filename matches for non-PKCS#11/agent keys that
1135                  * didn't load public keys. This supports the case
1136                  * of keeping just a private key file and public
1137                  * certificate on disk.
1138                  */
1139                 if (!matched && !id->isprivate && id->agent_fd == -1 &&
1140                     (id->key->flags & SSHKEY_FLAG_EXT) == 0) {
1141                         TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1142                                 if (private_id->key == NULL &&
1143                                     id_filename_matches(id, private_id)) {
1144                                         id = private_id;
1145                                         matched = 1;
1146                                         break;
1147                                 }
1148                         }
1149                 }
1150                 if (matched) {
1151                         debug2("%s: using private key \"%s\"%s for "
1152                             "certificate", __func__, id->filename,
1153                             id->agent_fd != -1 ? " from agent" : "");
1154                 } else {
1155                         debug("%s: no separate private key for certificate "
1156                             "\"%s\"", __func__, id->filename);
1157                 }
1158         }
1159
1160         /* generate signature */
1161         ret = identity_sign(id, &signature, &slen,
1162             buffer_ptr(&b), buffer_len(&b), datafellows);
1163         if (ret != 0) {
1164                 if (ret != SSH_ERR_KEY_NOT_FOUND)
1165                         error("%s: signing failed: %s", __func__, ssh_err(ret));
1166                 free(blob);
1167                 buffer_free(&b);
1168                 return 0;
1169         }
1170 #ifdef DEBUG_PK
1171         buffer_dump(&b);
1172 #endif
1173         if (datafellows & SSH_BUG_PKSERVICE) {
1174                 buffer_clear(&b);
1175                 buffer_append(&b, session_id2, session_id2_len);
1176                 skip = session_id2_len;
1177                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1178                 buffer_put_cstring(&b, authctxt->server_user);
1179                 buffer_put_cstring(&b, authctxt->service);
1180                 buffer_put_cstring(&b, authctxt->method->name);
1181                 buffer_put_char(&b, have_sig);
1182                 if (!(datafellows & SSH_BUG_PKAUTH))
1183                         buffer_put_cstring(&b, key_ssh_name(id->key));
1184                 buffer_put_string(&b, blob, bloblen);
1185         }
1186         free(blob);
1187
1188         /* append signature */
1189         buffer_put_string(&b, signature, slen);
1190         free(signature);
1191
1192         /* skip session id and packet type */
1193         if (buffer_len(&b) < skip + 1)
1194                 fatal("userauth_pubkey: internal error");
1195         buffer_consume(&b, skip + 1);
1196
1197         /* put remaining data from buffer into packet */
1198         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1199         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1200         buffer_free(&b);
1201         packet_send();
1202
1203         return 1;
1204 }
1205
1206 static int
1207 send_pubkey_test(Authctxt *authctxt, Identity *id)
1208 {
1209         u_char *blob;
1210         u_int bloblen, have_sig = 0;
1211
1212         debug3("send_pubkey_test");
1213
1214         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1215                 /* we cannot handle this key */
1216                 debug3("send_pubkey_test: cannot handle key");
1217                 return 0;
1218         }
1219         /* register callback for USERAUTH_PK_OK message */
1220         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1221
1222         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1223         packet_put_cstring(authctxt->server_user);
1224         packet_put_cstring(authctxt->service);
1225         packet_put_cstring(authctxt->method->name);
1226         packet_put_char(have_sig);
1227         if (!(datafellows & SSH_BUG_PKAUTH))
1228                 packet_put_cstring(key_sign_encode(id->key));
1229         packet_put_string(blob, bloblen);
1230         free(blob);
1231         packet_send();
1232         return 1;
1233 }
1234
1235 static struct sshkey *
1236 load_identity_file(Identity *id)
1237 {
1238         struct sshkey *private = NULL;
1239         char prompt[300], *passphrase, *comment;
1240         int r, perm_ok = 0, quit = 0, i;
1241         struct stat st;
1242
1243         if (stat(id->filename, &st) < 0) {
1244                 (id->userprovided ? logit : debug3)("no such identity: %s: %s",
1245                     id->filename, strerror(errno));
1246                 return NULL;
1247         }
1248         snprintf(prompt, sizeof prompt,
1249             "Enter passphrase for key '%.100s': ", id->filename);
1250         for (i = 0; i <= options.number_of_password_prompts; i++) {
1251                 if (i == 0)
1252                         passphrase = "";
1253                 else {
1254                         passphrase = read_passphrase(prompt, 0);
1255                         if (*passphrase == '\0') {
1256                                 debug2("no passphrase given, try next key");
1257                                 free(passphrase);
1258                                 break;
1259                         }
1260                 }
1261                 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename,
1262                     passphrase, &private, &comment, &perm_ok))) {
1263                 case 0:
1264                         break;
1265                 case SSH_ERR_KEY_WRONG_PASSPHRASE:
1266                         if (options.batch_mode) {
1267                                 quit = 1;
1268                                 break;
1269                         }
1270                         if (i != 0)
1271                                 debug2("bad passphrase given, try again...");
1272                         break;
1273                 case SSH_ERR_SYSTEM_ERROR:
1274                         if (errno == ENOENT) {
1275                                 debug2("Load key \"%s\": %s",
1276                                     id->filename, ssh_err(r));
1277                                 quit = 1;
1278                                 break;
1279                         }
1280                         /* FALLTHROUGH */
1281                 default:
1282                         error("Load key \"%s\": %s", id->filename, ssh_err(r));
1283                         quit = 1;
1284                         break;
1285                 }
1286                 if (!quit && private != NULL && id->agent_fd == -1 &&
1287                     !(id->key && id->isprivate))
1288                         maybe_add_key_to_agent(id->filename, private, comment,
1289                             passphrase);
1290                 if (i > 0) {
1291                         explicit_bzero(passphrase, strlen(passphrase));
1292                         free(passphrase);
1293                 }
1294                 free(comment);
1295                 if (private != NULL || quit)
1296                         break;
1297         }
1298         return private;
1299 }
1300
1301 /*
1302  * try keys in the following order:
1303  *      1. certificates listed in the config file
1304  *      2. other input certificates
1305  *      3. agent keys that are found in the config file
1306  *      4. other agent keys
1307  *      5. keys that are only listed in the config file
1308  */
1309 static void
1310 pubkey_prepare(Authctxt *authctxt)
1311 {
1312         struct identity *id, *id2, *tmp;
1313         struct idlist agent, files, *preferred;
1314         struct sshkey *key;
1315         int agent_fd = -1, i, r, found;
1316         size_t j;
1317         struct ssh_identitylist *idlist;
1318
1319         TAILQ_INIT(&agent);     /* keys from the agent */
1320         TAILQ_INIT(&files);     /* keys from the config file */
1321         preferred = &authctxt->keys;
1322         TAILQ_INIT(preferred);  /* preferred order of keys */
1323
1324         /* list of keys stored in the filesystem and PKCS#11 */
1325         for (i = 0; i < options.num_identity_files; i++) {
1326                 key = options.identity_keys[i];
1327                 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1328                         continue;
1329                 options.identity_keys[i] = NULL;
1330                 id = xcalloc(1, sizeof(*id));
1331                 id->agent_fd = -1;
1332                 id->key = key;
1333                 id->filename = xstrdup(options.identity_files[i]);
1334                 id->userprovided = options.identity_file_userprovided[i];
1335                 TAILQ_INSERT_TAIL(&files, id, next);
1336         }
1337         /* list of certificates specified by user */
1338         for (i = 0; i < options.num_certificate_files; i++) {
1339                 key = options.certificates[i];
1340                 if (!key_is_cert(key) || key->cert == NULL ||
1341                     key->cert->type != SSH2_CERT_TYPE_USER)
1342                         continue;
1343                 id = xcalloc(1, sizeof(*id));
1344                 id->agent_fd = -1;
1345                 id->key = key;
1346                 id->filename = xstrdup(options.certificate_files[i]);
1347                 id->userprovided = options.certificate_file_userprovided[i];
1348                 TAILQ_INSERT_TAIL(preferred, id, next);
1349         }
1350         /* list of keys supported by the agent */
1351         if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) {
1352                 if (r != SSH_ERR_AGENT_NOT_PRESENT)
1353                         debug("%s: ssh_get_authentication_socket: %s",
1354                             __func__, ssh_err(r));
1355         } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) {
1356                 if (r != SSH_ERR_AGENT_NO_IDENTITIES)
1357                         debug("%s: ssh_fetch_identitylist: %s",
1358                             __func__, ssh_err(r));
1359                 close(agent_fd);
1360         } else {
1361                 for (j = 0; j < idlist->nkeys; j++) {
1362                         found = 0;
1363                         TAILQ_FOREACH(id, &files, next) {
1364                                 /*
1365                                  * agent keys from the config file are
1366                                  * preferred
1367                                  */
1368                                 if (sshkey_equal(idlist->keys[j], id->key)) {
1369                                         TAILQ_REMOVE(&files, id, next);
1370                                         TAILQ_INSERT_TAIL(preferred, id, next);
1371                                         id->agent_fd = agent_fd;
1372                                         found = 1;
1373                                         break;
1374                                 }
1375                         }
1376                         if (!found && !options.identities_only) {
1377                                 id = xcalloc(1, sizeof(*id));
1378                                 /* XXX "steals" key/comment from idlist */
1379                                 id->key = idlist->keys[j];
1380                                 id->filename = idlist->comments[j];
1381                                 idlist->keys[j] = NULL;
1382                                 idlist->comments[j] = NULL;
1383                                 id->agent_fd = agent_fd;
1384                                 TAILQ_INSERT_TAIL(&agent, id, next);
1385                         }
1386                 }
1387                 ssh_free_identitylist(idlist);
1388                 /* append remaining agent keys */
1389                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1390                         TAILQ_REMOVE(&agent, id, next);
1391                         TAILQ_INSERT_TAIL(preferred, id, next);
1392                 }
1393                 authctxt->agent_fd = agent_fd;
1394         }
1395         /* Prefer PKCS11 keys that are explicitly listed */
1396         TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1397                 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0)
1398                         continue;
1399                 found = 0;
1400                 TAILQ_FOREACH(id2, &files, next) {
1401                         if (id2->key == NULL ||
1402                             (id2->key->flags & SSHKEY_FLAG_EXT) == 0)
1403                                 continue;
1404                         if (sshkey_equal(id->key, id2->key)) {
1405                                 TAILQ_REMOVE(&files, id, next);
1406                                 TAILQ_INSERT_TAIL(preferred, id, next);
1407                                 found = 1;
1408                                 break;
1409                         }
1410                 }
1411                 /* If IdentitiesOnly set and key not found then don't use it */
1412                 if (!found && options.identities_only) {
1413                         TAILQ_REMOVE(&files, id, next);
1414                         explicit_bzero(id, sizeof(*id));
1415                         free(id);
1416                 }
1417         }
1418         /* append remaining keys from the config file */
1419         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1420                 TAILQ_REMOVE(&files, id, next);
1421                 TAILQ_INSERT_TAIL(preferred, id, next);
1422         }
1423         /* finally, filter by PubkeyAcceptedKeyTypes */
1424         TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
1425                 if (id->key != NULL &&
1426                     match_pattern_list(sshkey_ssh_name(id->key),
1427                     options.pubkey_key_types, 0) != 1) {
1428                         debug("Skipping %s key %s - "
1429                             "not in PubkeyAcceptedKeyTypes",
1430                             sshkey_ssh_name(id->key), id->filename);
1431                         TAILQ_REMOVE(preferred, id, next);
1432                         sshkey_free(id->key);
1433                         free(id->filename);
1434                         memset(id, 0, sizeof(*id));
1435                         continue;
1436                 }
1437                 debug2("key: %s (%p)%s%s", id->filename, id->key,
1438                     id->userprovided ? ", explicit" : "",
1439                     id->agent_fd != -1 ? ", agent" : "");
1440         }
1441 }
1442
1443 static void
1444 pubkey_cleanup(Authctxt *authctxt)
1445 {
1446         Identity *id;
1447
1448         if (authctxt->agent_fd != -1)
1449                 ssh_close_authentication_socket(authctxt->agent_fd);
1450         for (id = TAILQ_FIRST(&authctxt->keys); id;
1451             id = TAILQ_FIRST(&authctxt->keys)) {
1452                 TAILQ_REMOVE(&authctxt->keys, id, next);
1453                 sshkey_free(id->key);
1454                 free(id->filename);
1455                 free(id);
1456         }
1457 }
1458
1459 static void
1460 pubkey_reset(Authctxt *authctxt)
1461 {
1462         Identity *id;
1463
1464         TAILQ_FOREACH(id, &authctxt->keys, next)
1465                 id->tried = 0;
1466 }
1467
1468 static int
1469 try_identity(Identity *id)
1470 {
1471         if (!id->key)
1472                 return (0);
1473         if (key_type_plain(id->key->type) == KEY_RSA &&
1474             (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1475                 debug("Skipped %s key %s for RSA/MD5 server",
1476                     key_type(id->key), id->filename);
1477                 return (0);
1478         }
1479         return 1;
1480 }
1481
1482 int
1483 userauth_pubkey(Authctxt *authctxt)
1484 {
1485         Identity *id;
1486         int sent = 0;
1487         char *fp;
1488
1489         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1490                 if (id->tried++)
1491                         return (0);
1492                 /* move key to the end of the queue */
1493                 TAILQ_REMOVE(&authctxt->keys, id, next);
1494                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1495                 /*
1496                  * send a test message if we have the public key. for
1497                  * encrypted keys we cannot do this and have to load the
1498                  * private key instead
1499                  */
1500                 if (id->key != NULL) {
1501                         if (try_identity(id)) {
1502                                 if ((fp = sshkey_fingerprint(id->key,
1503                                     options.fingerprint_hash,
1504                                     SSH_FP_DEFAULT)) == NULL) {
1505                                         error("%s: sshkey_fingerprint failed",
1506                                             __func__);
1507                                         return 0;
1508                                 }
1509                                 debug("Offering public key: %s %s %s",
1510                                     sshkey_type(id->key), fp, id->filename);
1511                                 free(fp);
1512                                 sent = send_pubkey_test(authctxt, id);
1513                         }
1514                 } else {
1515                         debug("Trying private key: %s", id->filename);
1516                         id->key = load_identity_file(id);
1517                         if (id->key != NULL) {
1518                                 if (try_identity(id)) {
1519                                         id->isprivate = 1;
1520                                         sent = sign_and_send_pubkey(
1521                                             authctxt, id);
1522                                 }
1523                                 key_free(id->key);
1524                                 id->key = NULL;
1525                                 id->isprivate = 0;
1526                         }
1527                 }
1528                 if (sent)
1529                         return (sent);
1530         }
1531         return (0);
1532 }
1533
1534 /*
1535  * Send userauth request message specifying keyboard-interactive method.
1536  */
1537 int
1538 userauth_kbdint(Authctxt *authctxt)
1539 {
1540         static int attempt = 0;
1541
1542         if (attempt++ >= options.number_of_password_prompts)
1543                 return 0;
1544         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1545         if (attempt > 1 && !authctxt->info_req_seen) {
1546                 debug3("userauth_kbdint: disable: no info_req_seen");
1547                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1548                 return 0;
1549         }
1550
1551         debug2("userauth_kbdint");
1552         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1553         packet_put_cstring(authctxt->server_user);
1554         packet_put_cstring(authctxt->service);
1555         packet_put_cstring(authctxt->method->name);
1556         packet_put_cstring("");                                 /* lang */
1557         packet_put_cstring(options.kbd_interactive_devices ?
1558             options.kbd_interactive_devices : "");
1559         packet_send();
1560
1561         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1562         return 1;
1563 }
1564
1565 /*
1566  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1567  */
1568 int
1569 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh)
1570 {
1571         Authctxt *authctxt = ssh->authctxt;
1572         char *name, *inst, *lang, *prompt, *response;
1573         u_int num_prompts, i;
1574         int echo = 0;
1575
1576         debug2("input_userauth_info_req");
1577
1578         if (authctxt == NULL)
1579                 fatal("input_userauth_info_req: no authentication context");
1580
1581         authctxt->info_req_seen = 1;
1582
1583         name = packet_get_string(NULL);
1584         inst = packet_get_string(NULL);
1585         lang = packet_get_string(NULL);
1586         if (strlen(name) > 0)
1587                 logit("%s", name);
1588         if (strlen(inst) > 0)
1589                 logit("%s", inst);
1590         free(name);
1591         free(inst);
1592         free(lang);
1593
1594         num_prompts = packet_get_int();
1595         /*
1596          * Begin to build info response packet based on prompts requested.
1597          * We commit to providing the correct number of responses, so if
1598          * further on we run into a problem that prevents this, we have to
1599          * be sure and clean this up and send a correct error response.
1600          */
1601         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1602         packet_put_int(num_prompts);
1603
1604         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1605         for (i = 0; i < num_prompts; i++) {
1606                 prompt = packet_get_string(NULL);
1607                 echo = packet_get_char();
1608
1609                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1610
1611                 packet_put_cstring(response);
1612                 explicit_bzero(response, strlen(response));
1613                 free(response);
1614                 free(prompt);
1615         }
1616         packet_check_eom(); /* done with parsing incoming message. */
1617
1618         packet_add_padding(64);
1619         packet_send();
1620         return 0;
1621 }
1622
1623 static int
1624 ssh_keysign(struct sshkey *key, u_char **sigp, size_t *lenp,
1625     const u_char *data, size_t datalen)
1626 {
1627         struct sshbuf *b;
1628         struct stat st;
1629         pid_t pid;
1630         int i, r, to[2], from[2], status, sock = packet_get_connection_in();
1631         u_char rversion = 0, version = 2;
1632         void (*osigchld)(int);
1633
1634         *sigp = NULL;
1635         *lenp = 0;
1636
1637         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1638                 error("%s: not installed: %s", __func__, strerror(errno));
1639                 return -1;
1640         }
1641         if (fflush(stdout) != 0) {
1642                 error("%s: fflush: %s", __func__, strerror(errno));
1643                 return -1;
1644         }
1645         if (pipe(to) < 0) {
1646                 error("%s: pipe: %s", __func__, strerror(errno));
1647                 return -1;
1648         }
1649         if (pipe(from) < 0) {
1650                 error("%s: pipe: %s", __func__, strerror(errno));
1651                 return -1;
1652         }
1653         if ((pid = fork()) < 0) {
1654                 error("%s: fork: %s", __func__, strerror(errno));
1655                 return -1;
1656         }
1657         osigchld = signal(SIGCHLD, SIG_DFL);
1658         if (pid == 0) {
1659                 /* keep the socket on exec */
1660                 fcntl(sock, F_SETFD, 0);
1661                 permanently_drop_suid(getuid());
1662                 close(from[0]);
1663                 if (dup2(from[1], STDOUT_FILENO) < 0)
1664                         fatal("%s: dup2: %s", __func__, strerror(errno));
1665                 close(to[1]);
1666                 if (dup2(to[0], STDIN_FILENO) < 0)
1667                         fatal("%s: dup2: %s", __func__, strerror(errno));
1668                 close(from[1]);
1669                 close(to[0]);
1670                 /* Close everything but stdio and the socket */
1671                 for (i = STDERR_FILENO + 1; i < sock; i++)
1672                         close(i);
1673                 closefrom(sock + 1);
1674                 debug3("%s: [child] pid=%ld, exec %s",
1675                     __func__, (long)getpid(), _PATH_SSH_KEY_SIGN);
1676                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL);
1677                 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN,
1678                     strerror(errno));
1679         }
1680         close(from[1]);
1681         close(to[0]);
1682
1683         if ((b = sshbuf_new()) == NULL)
1684                 fatal("%s: sshbuf_new failed", __func__);
1685         /* send # of sock, data to be signed */
1686         if ((r = sshbuf_put_u32(b, sock)) != 0 ||
1687             (r = sshbuf_put_string(b, data, datalen)) != 0)
1688                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1689         if (ssh_msg_send(to[1], version, b) == -1)
1690                 fatal("%s: couldn't send request", __func__);
1691         sshbuf_reset(b);
1692         r = ssh_msg_recv(from[0], b);
1693         close(from[0]);
1694         close(to[1]);
1695         if (r < 0) {
1696                 error("%s: no reply", __func__);
1697                 goto fail;
1698         }
1699
1700         errno = 0;
1701         while (waitpid(pid, &status, 0) < 0) {
1702                 if (errno != EINTR) {
1703                         error("%s: waitpid %ld: %s",
1704                             __func__, (long)pid, strerror(errno));
1705                         goto fail;
1706                 }
1707         }
1708         if (!WIFEXITED(status)) {
1709                 error("%s: exited abnormally", __func__);
1710                 goto fail;
1711         }
1712         if (WEXITSTATUS(status) != 0) {
1713                 error("%s: exited with status %d",
1714                     __func__, WEXITSTATUS(status));
1715                 goto fail;
1716         }
1717         if ((r = sshbuf_get_u8(b, &rversion)) != 0) {
1718                 error("%s: buffer error: %s", __func__, ssh_err(r));
1719                 goto fail;
1720         }
1721         if (rversion != version) {
1722                 error("%s: bad version", __func__);
1723                 goto fail;
1724         }
1725         if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) {
1726                 error("%s: buffer error: %s", __func__, ssh_err(r));
1727  fail:
1728                 signal(SIGCHLD, osigchld);
1729                 sshbuf_free(b);
1730                 return -1;
1731         }
1732         signal(SIGCHLD, osigchld);
1733         sshbuf_free(b);
1734
1735         return 0;
1736 }
1737
1738 int
1739 userauth_hostbased(Authctxt *authctxt)
1740 {
1741         struct ssh *ssh = active_state;
1742         struct sshkey *private = NULL;
1743         struct sshbuf *b = NULL;
1744         const char *service;
1745         u_char *sig = NULL, *keyblob = NULL;
1746         char *fp = NULL, *chost = NULL, *lname = NULL;
1747         size_t siglen = 0, keylen = 0;
1748         int i, r, success = 0;
1749
1750         if (authctxt->ktypes == NULL) {
1751                 authctxt->oktypes = xstrdup(options.hostbased_key_types);
1752                 authctxt->ktypes = authctxt->oktypes;
1753         }
1754
1755         /*
1756          * Work through each listed type pattern in HostbasedKeyTypes,
1757          * trying each hostkey that matches the type in turn.
1758          */
1759         for (;;) {
1760                 if (authctxt->active_ktype == NULL)
1761                         authctxt->active_ktype = strsep(&authctxt->ktypes, ",");
1762                 if (authctxt->active_ktype == NULL ||
1763                     *authctxt->active_ktype == '\0')
1764                         break;
1765                 debug3("%s: trying key type %s", __func__,
1766                     authctxt->active_ktype);
1767
1768                 /* check for a useful key */
1769                 private = NULL;
1770                 for (i = 0; i < authctxt->sensitive->nkeys; i++) {
1771                         if (authctxt->sensitive->keys[i] == NULL ||
1772                             authctxt->sensitive->keys[i]->type == KEY_UNSPEC)
1773                                 continue;
1774                         if (match_pattern_list(
1775                             sshkey_ssh_name(authctxt->sensitive->keys[i]),
1776                             authctxt->active_ktype, 0) != 1)
1777                                 continue;
1778                         /* we take and free the key */
1779                         private = authctxt->sensitive->keys[i];
1780                         authctxt->sensitive->keys[i] = NULL;
1781                         break;
1782                 }
1783                 /* Found one */
1784                 if (private != NULL)
1785                         break;
1786                 /* No more keys of this type; advance */
1787                 authctxt->active_ktype = NULL;
1788         }
1789         if (private == NULL) {
1790                 free(authctxt->oktypes);
1791                 authctxt->oktypes = authctxt->ktypes = NULL;
1792                 authctxt->active_ktype = NULL;
1793                 debug("No more client hostkeys for hostbased authentication.");
1794                 goto out;
1795         }
1796
1797         if ((fp = sshkey_fingerprint(private, options.fingerprint_hash,
1798             SSH_FP_DEFAULT)) == NULL) {
1799                 error("%s: sshkey_fingerprint failed", __func__);
1800                 goto out;
1801         }
1802         debug("%s: trying hostkey %s %s",
1803             __func__, sshkey_ssh_name(private), fp);
1804
1805         /* figure out a name for the client host */
1806         if ((lname = get_local_name(packet_get_connection_in())) == NULL) {
1807                 error("%s: cannot get local ipaddr/name", __func__);
1808                 goto out;
1809         }
1810
1811         /* XXX sshbuf_put_stringf? */
1812         xasprintf(&chost, "%s.", lname);
1813         debug2("%s: chost %s", __func__, chost);
1814
1815         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1816             authctxt->service;
1817
1818         /* construct data */
1819         if ((b = sshbuf_new()) == NULL) {
1820                 error("%s: sshbuf_new failed", __func__);
1821                 goto out;
1822         }
1823         if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) {
1824                 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r));
1825                 goto out;
1826         }
1827         if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 ||
1828             (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1829             (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
1830             (r = sshbuf_put_cstring(b, service)) != 0 ||
1831             (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
1832             (r = sshbuf_put_cstring(b, key_ssh_name(private))) != 0 ||
1833             (r = sshbuf_put_string(b, keyblob, keylen)) != 0 ||
1834             (r = sshbuf_put_cstring(b, chost)) != 0 ||
1835             (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) {
1836                 error("%s: buffer error: %s", __func__, ssh_err(r));
1837                 goto out;
1838         }
1839
1840 #ifdef DEBUG_PK
1841         sshbuf_dump(b, stderr);
1842 #endif
1843         if (authctxt->sensitive->external_keysign)
1844                 r = ssh_keysign(private, &sig, &siglen,
1845                     sshbuf_ptr(b), sshbuf_len(b));
1846         else if ((r = sshkey_sign(private, &sig, &siglen,
1847             sshbuf_ptr(b), sshbuf_len(b), NULL, datafellows)) != 0)
1848                 debug("%s: sshkey_sign: %s", __func__, ssh_err(r));
1849         if (r != 0) {
1850                 error("sign using hostkey %s %s failed",
1851                     sshkey_ssh_name(private), fp);
1852                 goto out;
1853         }
1854         if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1855             (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1856             (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1857             (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1858             (r = sshpkt_put_cstring(ssh, key_ssh_name(private))) != 0 ||
1859             (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 ||
1860             (r = sshpkt_put_cstring(ssh, chost)) != 0 ||
1861             (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 ||
1862             (r = sshpkt_put_string(ssh, sig, siglen)) != 0 ||
1863             (r = sshpkt_send(ssh)) != 0) {
1864                 error("%s: packet error: %s", __func__, ssh_err(r));
1865                 goto out;
1866         }
1867         success = 1;
1868
1869  out:
1870         if (sig != NULL) {
1871                 explicit_bzero(sig, siglen);
1872                 free(sig);
1873         }
1874         free(keyblob);
1875         free(lname);
1876         free(fp);
1877         free(chost);
1878         sshkey_free(private);
1879         sshbuf_free(b);
1880
1881         return success;
1882 }
1883
1884 /* find auth method */
1885
1886 /*
1887  * given auth method name, if configurable options permit this method fill
1888  * in auth_ident field and return true, otherwise return false.
1889  */
1890 static int
1891 authmethod_is_enabled(Authmethod *method)
1892 {
1893         if (method == NULL)
1894                 return 0;
1895         /* return false if options indicate this method is disabled */
1896         if  (method->enabled == NULL || *method->enabled == 0)
1897                 return 0;
1898         /* return false if batch mode is enabled but method needs interactive mode */
1899         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1900                 return 0;
1901         return 1;
1902 }
1903
1904 static Authmethod *
1905 authmethod_lookup(const char *name)
1906 {
1907         Authmethod *method = NULL;
1908         if (name != NULL)
1909                 for (method = authmethods; method->name != NULL; method++)
1910                         if (strcmp(name, method->name) == 0)
1911                                 return method;
1912         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1913         return NULL;
1914 }
1915
1916 /* XXX internal state */
1917 static Authmethod *current = NULL;
1918 static char *supported = NULL;
1919 static char *preferred = NULL;
1920
1921 /*
1922  * Given the authentication method list sent by the server, return the
1923  * next method we should try.  If the server initially sends a nil list,
1924  * use a built-in default list.
1925  */
1926 static Authmethod *
1927 authmethod_get(char *authlist)
1928 {
1929         char *name = NULL;
1930         u_int next;
1931
1932         /* Use a suitable default if we're passed a nil list.  */
1933         if (authlist == NULL || strlen(authlist) == 0)
1934                 authlist = options.preferred_authentications;
1935
1936         if (supported == NULL || strcmp(authlist, supported) != 0) {
1937                 debug3("start over, passed a different list %s", authlist);
1938                 free(supported);
1939                 supported = xstrdup(authlist);
1940                 preferred = options.preferred_authentications;
1941                 debug3("preferred %s", preferred);
1942                 current = NULL;
1943         } else if (current != NULL && authmethod_is_enabled(current))
1944                 return current;
1945
1946         for (;;) {
1947                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1948                         debug("No more authentication methods to try.");
1949                         current = NULL;
1950                         return NULL;
1951                 }
1952                 preferred += next;
1953                 debug3("authmethod_lookup %s", name);
1954                 debug3("remaining preferred: %s", preferred);
1955                 if ((current = authmethod_lookup(name)) != NULL &&
1956                     authmethod_is_enabled(current)) {
1957                         debug3("authmethod_is_enabled %s", name);
1958                         debug("Next authentication method: %s", name);
1959                         free(name);
1960                         return current;
1961                 }
1962                 free(name);
1963         }
1964 }
1965
1966 static char *
1967 authmethods_get(void)
1968 {
1969         Authmethod *method = NULL;
1970         Buffer b;
1971         char *list;
1972
1973         buffer_init(&b);
1974         for (method = authmethods; method->name != NULL; method++) {
1975                 if (authmethod_is_enabled(method)) {
1976                         if (buffer_len(&b) > 0)
1977                                 buffer_append(&b, ",", 1);
1978                         buffer_append(&b, method->name, strlen(method->name));
1979                 }
1980         }
1981         if ((list = sshbuf_dup_string(&b)) == NULL)
1982                 fatal("%s: sshbuf_dup_string failed", __func__);
1983         buffer_free(&b);
1984         return list;
1985 }
1986