crypto/openssh/sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.251 2016/12/04 23:54:02 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((u_int32_t)options.rekey_limit,
 197                     (time_t)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 = options.host_key_alias ? options.host_key_alias :
 938             authctxt->host;
 939
 940         debug2("input_userauth_passwd_changereq");
 941
 942         if (authctxt == NULL)
 943                 fatal("input_userauth_passwd_changereq: "
 944                     "no authentication context");
 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 identity_sign_encode(struct identity *id)
1000 {
1001         struct ssh *ssh = active_state;
1002
1003         if (id->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(id->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         const char *alg;
1021
1022         alg = identity_sign_encode(id);
1023
1024         /* the agent supports this key */
1025         if (id->agent_fd != -1)
1026                 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp,
1027                     data, datalen, alg, compat);
1028
1029         /*
1030          * we have already loaded the private key or
1031          * the private key is stored in external hardware
1032          */
1033         if (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))
1034                 return (sshkey_sign(id->key, sigp, lenp, data, datalen, alg,
1035                     compat));
1036         /* load the private key from the file */
1037         if ((prv = load_identity_file(id)) == NULL)
1038                 return SSH_ERR_KEY_NOT_FOUND;
1039         ret = sshkey_sign(prv, sigp, lenp, data, datalen, alg, compat);
1040         sshkey_free(prv);
1041         return (ret);
1042 }
1043
1044 static int
1045 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1046 {
1047         Buffer b;
1048         Identity *private_id;
1049         u_char *blob, *signature;
1050         size_t slen;
1051         u_int bloblen, skip = 0;
1052         int matched, ret = -1, have_sig = 1;
1053         char *fp;
1054
1055         if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
1056             SSH_FP_DEFAULT)) == NULL)
1057                 return 0;
1058         debug3("%s: %s %s", __func__, key_type(id->key), fp);
1059         free(fp);
1060
1061         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1062                 /* we cannot handle this key */
1063                 debug3("sign_and_send_pubkey: cannot handle key");
1064                 return 0;
1065         }
1066         /* data to be signed */
1067         buffer_init(&b);
1068         if (datafellows & SSH_OLD_SESSIONID) {
1069                 buffer_append(&b, session_id2, session_id2_len);
1070                 skip = session_id2_len;
1071         } else {
1072                 buffer_put_string(&b, session_id2, session_id2_len);
1073                 skip = buffer_len(&b);
1074         }
1075         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1076         buffer_put_cstring(&b, authctxt->server_user);
1077         buffer_put_cstring(&b,
1078             datafellows & SSH_BUG_PKSERVICE ?
1079             "ssh-userauth" :
1080             authctxt->service);
1081         if (datafellows & SSH_BUG_PKAUTH) {
1082                 buffer_put_char(&b, have_sig);
1083         } else {
1084                 buffer_put_cstring(&b, authctxt->method->name);
1085                 buffer_put_char(&b, have_sig);
1086                 buffer_put_cstring(&b, identity_sign_encode(id));
1087         }
1088         buffer_put_string(&b, blob, bloblen);
1089
1090         /*
1091          * If the key is an certificate, try to find a matching private key
1092          * and use it to complete the signature.
1093          * If no such private key exists, fall back to trying the certificate
1094          * key itself in case it has a private half already loaded.
1095          */
1096         if (key_is_cert(id->key)) {
1097                 matched = 0;
1098                 TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1099                         if (sshkey_equal_public(id->key, private_id->key) &&
1100                             id->key->type != private_id->key->type) {
1101                                 id = private_id;
1102                                 matched = 1;
1103                                 break;
1104                         }
1105                 }
1106                 if (matched) {
1107                         debug2("%s: using private key \"%s\"%s for "
1108                             "certificate", __func__, id->filename,
1109                             id->agent_fd != -1 ? " from agent" : "");
1110                 } else {
1111                         debug("%s: no separate private key for certificate "
1112                             "\"%s\"", __func__, id->filename);
1113                 }
1114         }
1115
1116         /* generate signature */
1117         ret = identity_sign(id, &signature, &slen,
1118             buffer_ptr(&b), buffer_len(&b), datafellows);
1119         if (ret != 0) {
1120                 if (ret != SSH_ERR_KEY_NOT_FOUND)
1121                         error("%s: signing failed: %s", __func__, ssh_err(ret));
1122                 free(blob);
1123                 buffer_free(&b);
1124                 return 0;
1125         }
1126 #ifdef DEBUG_PK
1127         buffer_dump(&b);
1128 #endif
1129         if (datafellows & SSH_BUG_PKSERVICE) {
1130                 buffer_clear(&b);
1131                 buffer_append(&b, session_id2, session_id2_len);
1132                 skip = session_id2_len;
1133                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1134                 buffer_put_cstring(&b, authctxt->server_user);
1135                 buffer_put_cstring(&b, authctxt->service);
1136                 buffer_put_cstring(&b, authctxt->method->name);
1137                 buffer_put_char(&b, have_sig);
1138                 if (!(datafellows & SSH_BUG_PKAUTH))
1139                         buffer_put_cstring(&b, key_ssh_name(id->key));
1140                 buffer_put_string(&b, blob, bloblen);
1141         }
1142         free(blob);
1143
1144         /* append signature */
1145         buffer_put_string(&b, signature, slen);
1146         free(signature);
1147
1148         /* skip session id and packet type */
1149         if (buffer_len(&b) < skip + 1)
1150                 fatal("userauth_pubkey: internal error");
1151         buffer_consume(&b, skip + 1);
1152
1153         /* put remaining data from buffer into packet */
1154         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1155         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1156         buffer_free(&b);
1157         packet_send();
1158
1159         return 1;
1160 }
1161
1162 static int
1163 send_pubkey_test(Authctxt *authctxt, Identity *id)
1164 {
1165         u_char *blob;
1166         u_int bloblen, have_sig = 0;
1167
1168         debug3("send_pubkey_test");
1169
1170         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1171                 /* we cannot handle this key */
1172                 debug3("send_pubkey_test: cannot handle key");
1173                 return 0;
1174         }
1175         /* register callback for USERAUTH_PK_OK message */
1176         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1177
1178         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1179         packet_put_cstring(authctxt->server_user);
1180         packet_put_cstring(authctxt->service);
1181         packet_put_cstring(authctxt->method->name);
1182         packet_put_char(have_sig);
1183         if (!(datafellows & SSH_BUG_PKAUTH))
1184                 packet_put_cstring(identity_sign_encode(id));
1185         packet_put_string(blob, bloblen);
1186         free(blob);
1187         packet_send();
1188         return 1;
1189 }
1190
1191 static Key *
1192 load_identity_file(Identity *id)
1193 {
1194         Key *private = NULL;
1195         char prompt[300], *passphrase, *comment;
1196         int r, perm_ok = 0, quit = 0, i;
1197         struct stat st;
1198
1199         if (stat(id->filename, &st) < 0) {
1200                 (id->userprovided ? logit : debug3)("no such identity: %s: %s",
1201                     id->filename, strerror(errno));
1202                 return NULL;
1203         }
1204         snprintf(prompt, sizeof prompt,
1205             "Enter passphrase for key '%.100s': ", id->filename);
1206         for (i = 0; i <= options.number_of_password_prompts; i++) {
1207                 if (i == 0)
1208                         passphrase = "";
1209                 else {
1210                         passphrase = read_passphrase(prompt, 0);
1211                         if (*passphrase == '\0') {
1212                                 debug2("no passphrase given, try next key");
1213                                 free(passphrase);
1214                                 break;
1215                         }
1216                 }
1217                 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename,
1218                     passphrase, &private, &comment, &perm_ok))) {
1219                 case 0:
1220                         break;
1221                 case SSH_ERR_KEY_WRONG_PASSPHRASE:
1222                         if (options.batch_mode) {
1223                                 quit = 1;
1224                                 break;
1225                         }
1226                         if (i != 0)
1227                                 debug2("bad passphrase given, try again...");
1228                         break;
1229                 case SSH_ERR_SYSTEM_ERROR:
1230                         if (errno == ENOENT) {
1231                                 debug2("Load key \"%s\": %s",
1232                                     id->filename, ssh_err(r));
1233                                 quit = 1;
1234                                 break;
1235                         }
1236                         /* FALLTHROUGH */
1237                 default:
1238                         error("Load key \"%s\": %s", id->filename, ssh_err(r));
1239                         quit = 1;
1240                         break;
1241                 }
1242                 if (!quit && private != NULL && id->agent_fd == -1 &&
1243                     !(id->key && id->isprivate))
1244                         maybe_add_key_to_agent(id->filename, private, comment,
1245                             passphrase);
1246                 if (i > 0) {
1247                         explicit_bzero(passphrase, strlen(passphrase));
1248                         free(passphrase);
1249                 }
1250                 free(comment);
1251                 if (private != NULL || quit)
1252                         break;
1253         }
1254         return private;
1255 }
1256
1257 /*
1258  * try keys in the following order:
1259  *      1. certificates listed in the config file
1260  *      2. other input certificates
1261  *      3. agent keys that are found in the config file
1262  *      4. other agent keys
1263  *      5. keys that are only listed in the config file
1264  */
1265 static void
1266 pubkey_prepare(Authctxt *authctxt)
1267 {
1268         struct identity *id, *id2, *tmp;
1269         struct idlist agent, files, *preferred;
1270         struct sshkey *key;
1271         int agent_fd = -1, i, r, found;
1272         size_t j;
1273         struct ssh_identitylist *idlist;
1274
1275         TAILQ_INIT(&agent);     /* keys from the agent */
1276         TAILQ_INIT(&files);     /* keys from the config file */
1277         preferred = &authctxt->keys;
1278         TAILQ_INIT(preferred);  /* preferred order of keys */
1279
1280         /* list of keys stored in the filesystem and PKCS#11 */
1281         for (i = 0; i < options.num_identity_files; i++) {
1282                 key = options.identity_keys[i];
1283                 if (key && key->type == KEY_RSA1)
1284                         continue;
1285                 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1286                         continue;
1287                 options.identity_keys[i] = NULL;
1288                 id = xcalloc(1, sizeof(*id));
1289                 id->agent_fd = -1;
1290                 id->key = key;
1291                 id->filename = xstrdup(options.identity_files[i]);
1292                 id->userprovided = options.identity_file_userprovided[i];
1293                 TAILQ_INSERT_TAIL(&files, id, next);
1294         }
1295         /* list of certificates specified by user */
1296         for (i = 0; i < options.num_certificate_files; i++) {
1297                 key = options.certificates[i];
1298                 if (!key_is_cert(key) || key->cert == NULL ||
1299                     key->cert->type != SSH2_CERT_TYPE_USER)
1300                         continue;
1301                 id = xcalloc(1, sizeof(*id));
1302                 id->agent_fd = -1;
1303                 id->key = key;
1304                 id->filename = xstrdup(options.certificate_files[i]);
1305                 id->userprovided = options.certificate_file_userprovided[i];
1306                 TAILQ_INSERT_TAIL(preferred, id, next);
1307         }
1308         /* list of keys supported by the agent */
1309         if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) {
1310                 if (r != SSH_ERR_AGENT_NOT_PRESENT)
1311                         debug("%s: ssh_get_authentication_socket: %s",
1312                             __func__, ssh_err(r));
1313         } else if ((r = ssh_fetch_identitylist(agent_fd, 2, &idlist)) != 0) {
1314                 if (r != SSH_ERR_AGENT_NO_IDENTITIES)
1315                         debug("%s: ssh_fetch_identitylist: %s",
1316                             __func__, ssh_err(r));
1317                 close(agent_fd);
1318         } else {
1319                 for (j = 0; j < idlist->nkeys; j++) {
1320                         found = 0;
1321                         TAILQ_FOREACH(id, &files, next) {
1322                                 /*
1323                                  * agent keys from the config file are
1324                                  * preferred
1325                                  */
1326                                 if (sshkey_equal(idlist->keys[j], id->key)) {
1327                                         TAILQ_REMOVE(&files, id, next);
1328                                         TAILQ_INSERT_TAIL(preferred, id, next);
1329                                         id->agent_fd = agent_fd;
1330                                         found = 1;
1331                                         break;
1332                                 }
1333                         }
1334                         if (!found && !options.identities_only) {
1335                                 id = xcalloc(1, sizeof(*id));
1336                                 /* XXX "steals" key/comment from idlist */
1337                                 id->key = idlist->keys[j];
1338                                 id->filename = idlist->comments[j];
1339                                 idlist->keys[j] = NULL;
1340                                 idlist->comments[j] = NULL;
1341                                 id->agent_fd = agent_fd;
1342                                 TAILQ_INSERT_TAIL(&agent, id, next);
1343                         }
1344                 }
1345                 ssh_free_identitylist(idlist);
1346                 /* append remaining agent keys */
1347                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1348                         TAILQ_REMOVE(&agent, id, next);
1349                         TAILQ_INSERT_TAIL(preferred, id, next);
1350                 }
1351                 authctxt->agent_fd = agent_fd;
1352         }
1353         /* Prefer PKCS11 keys that are explicitly listed */
1354         TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1355                 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0)
1356                         continue;
1357                 found = 0;
1358                 TAILQ_FOREACH(id2, &files, next) {
1359                         if (id2->key == NULL ||
1360                             (id2->key->flags & SSHKEY_FLAG_EXT) == 0)
1361                                 continue;
1362                         if (sshkey_equal(id->key, id2->key)) {
1363                                 TAILQ_REMOVE(&files, id, next);
1364                                 TAILQ_INSERT_TAIL(preferred, id, next);
1365                                 found = 1;
1366                                 break;
1367                         }
1368                 }
1369                 /* If IdentitiesOnly set and key not found then don't use it */
1370                 if (!found && options.identities_only) {
1371                         TAILQ_REMOVE(&files, id, next);
1372                         explicit_bzero(id, sizeof(*id));
1373                         free(id);
1374                 }
1375         }
1376         /* append remaining keys from the config file */
1377         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1378                 TAILQ_REMOVE(&files, id, next);
1379                 TAILQ_INSERT_TAIL(preferred, id, next);
1380         }
1381         /* finally, filter by PubkeyAcceptedKeyTypes */
1382         TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
1383                 if (id->key != NULL &&
1384                     match_pattern_list(sshkey_ssh_name(id->key),
1385                     options.pubkey_key_types, 0) != 1) {
1386                         debug("Skipping %s key %s - "
1387                             "not in PubkeyAcceptedKeyTypes",
1388                             sshkey_ssh_name(id->key), id->filename);
1389                         TAILQ_REMOVE(preferred, id, next);
1390                         sshkey_free(id->key);
1391                         free(id->filename);
1392                         memset(id, 0, sizeof(*id));
1393                         continue;
1394                 }
1395                 debug2("key: %s (%p)%s%s", id->filename, id->key,
1396                     id->userprovided ? ", explicit" : "",
1397                     id->agent_fd != -1 ? ", agent" : "");
1398         }
1399 }
1400
1401 static void
1402 pubkey_cleanup(Authctxt *authctxt)
1403 {
1404         Identity *id;
1405
1406         if (authctxt->agent_fd != -1)
1407                 ssh_close_authentication_socket(authctxt->agent_fd);
1408         for (id = TAILQ_FIRST(&authctxt->keys); id;
1409             id = TAILQ_FIRST(&authctxt->keys)) {
1410                 TAILQ_REMOVE(&authctxt->keys, id, next);
1411                 sshkey_free(id->key);
1412                 free(id->filename);
1413                 free(id);
1414         }
1415 }
1416
1417 static void
1418 pubkey_reset(Authctxt *authctxt)
1419 {
1420         Identity *id;
1421
1422         TAILQ_FOREACH(id, &authctxt->keys, next)
1423                 id->tried = 0;
1424 }
1425
1426 static int
1427 try_identity(Identity *id)
1428 {
1429         if (!id->key)
1430                 return (0);
1431         if (key_type_plain(id->key->type) == KEY_RSA &&
1432             (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1433                 debug("Skipped %s key %s for RSA/MD5 server",
1434                     key_type(id->key), id->filename);
1435                 return (0);
1436         }
1437         return (id->key->type != KEY_RSA1);
1438 }
1439
1440 int
1441 userauth_pubkey(Authctxt *authctxt)
1442 {
1443         Identity *id;
1444         int sent = 0;
1445
1446         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1447                 if (id->tried++)
1448                         return (0);
1449                 /* move key to the end of the queue */
1450                 TAILQ_REMOVE(&authctxt->keys, id, next);
1451                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1452                 /*
1453                  * send a test message if we have the public key. for
1454                  * encrypted keys we cannot do this and have to load the
1455                  * private key instead
1456                  */
1457                 if (id->key != NULL) {
1458                         if (try_identity(id)) {
1459                                 debug("Offering %s public key: %s",
1460                                     key_type(id->key), id->filename);
1461                                 sent = send_pubkey_test(authctxt, id);
1462                         }
1463                 } else {
1464                         debug("Trying private key: %s", id->filename);
1465                         id->key = load_identity_file(id);
1466                         if (id->key != NULL) {
1467                                 if (try_identity(id)) {
1468                                         id->isprivate = 1;
1469                                         sent = sign_and_send_pubkey(
1470                                             authctxt, id);
1471                                 }
1472                                 key_free(id->key);
1473                                 id->key = NULL;
1474                                 id->isprivate = 0;
1475                         }
1476                 }
1477                 if (sent)
1478                         return (sent);
1479         }
1480         return (0);
1481 }
1482
1483 /*
1484  * Send userauth request message specifying keyboard-interactive method.
1485  */
1486 int
1487 userauth_kbdint(Authctxt *authctxt)
1488 {
1489         static int attempt = 0;
1490
1491         if (attempt++ >= options.number_of_password_prompts)
1492                 return 0;
1493         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1494         if (attempt > 1 && !authctxt->info_req_seen) {
1495                 debug3("userauth_kbdint: disable: no info_req_seen");
1496                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1497                 return 0;
1498         }
1499
1500         debug2("userauth_kbdint");
1501         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1502         packet_put_cstring(authctxt->server_user);
1503         packet_put_cstring(authctxt->service);
1504         packet_put_cstring(authctxt->method->name);
1505         packet_put_cstring("");                                 /* lang */
1506         packet_put_cstring(options.kbd_interactive_devices ?
1507             options.kbd_interactive_devices : "");
1508         packet_send();
1509
1510         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1511         return 1;
1512 }
1513
1514 /*
1515  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1516  */
1517 int
1518 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1519 {
1520         Authctxt *authctxt = ctxt;
1521         char *name, *inst, *lang, *prompt, *response;
1522         u_int num_prompts, i;
1523         int echo = 0;
1524
1525         debug2("input_userauth_info_req");
1526
1527         if (authctxt == NULL)
1528                 fatal("input_userauth_info_req: no authentication context");
1529
1530         authctxt->info_req_seen = 1;
1531
1532         name = packet_get_string(NULL);
1533         inst = packet_get_string(NULL);
1534         lang = packet_get_string(NULL);
1535         if (strlen(name) > 0)
1536                 logit("%s", name);
1537         if (strlen(inst) > 0)
1538                 logit("%s", inst);
1539         free(name);
1540         free(inst);
1541         free(lang);
1542
1543         num_prompts = packet_get_int();
1544         /*
1545          * Begin to build info response packet based on prompts requested.
1546          * We commit to providing the correct number of responses, so if
1547          * further on we run into a problem that prevents this, we have to
1548          * be sure and clean this up and send a correct error response.
1549          */
1550         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1551         packet_put_int(num_prompts);
1552
1553         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1554         for (i = 0; i < num_prompts; i++) {
1555                 prompt = packet_get_string(NULL);
1556                 echo = packet_get_char();
1557
1558                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1559
1560                 packet_put_cstring(response);
1561                 explicit_bzero(response, strlen(response));
1562                 free(response);
1563                 free(prompt);
1564         }
1565         packet_check_eom(); /* done with parsing incoming message. */
1566
1567         packet_add_padding(64);
1568         packet_send();
1569         return 0;
1570 }
1571
1572 static int
1573 ssh_keysign(struct sshkey *key, u_char **sigp, size_t *lenp,
1574     const u_char *data, size_t datalen)
1575 {
1576         struct sshbuf *b;
1577         struct stat st;
1578         pid_t pid;
1579         int i, r, to[2], from[2], status, sock = packet_get_connection_in();
1580         u_char rversion = 0, version = 2;
1581         void (*osigchld)(int);
1582
1583         *sigp = NULL;
1584         *lenp = 0;
1585
1586         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1587                 error("%s: not installed: %s", __func__, strerror(errno));
1588                 return -1;
1589         }
1590         if (fflush(stdout) != 0) {
1591                 error("%s: fflush: %s", __func__, strerror(errno));
1592                 return -1;
1593         }
1594         if (pipe(to) < 0) {
1595                 error("%s: pipe: %s", __func__, strerror(errno));
1596                 return -1;
1597         }
1598         if (pipe(from) < 0) {
1599                 error("%s: pipe: %s", __func__, strerror(errno));
1600                 return -1;
1601         }
1602         if ((pid = fork()) < 0) {
1603                 error("%s: fork: %s", __func__, strerror(errno));
1604                 return -1;
1605         }
1606         osigchld = signal(SIGCHLD, SIG_DFL);
1607         if (pid == 0) {
1608                 /* keep the socket on exec */
1609                 fcntl(sock, F_SETFD, 0);
1610                 permanently_drop_suid(getuid());
1611                 close(from[0]);
1612                 if (dup2(from[1], STDOUT_FILENO) < 0)
1613                         fatal("%s: dup2: %s", __func__, strerror(errno));
1614                 close(to[1]);
1615                 if (dup2(to[0], STDIN_FILENO) < 0)
1616                         fatal("%s: dup2: %s", __func__, strerror(errno));
1617                 close(from[1]);
1618                 close(to[0]);
1619                 /* Close everything but stdio and the socket */
1620                 for (i = STDERR_FILENO + 1; i < sock; i++)
1621                         close(i);
1622                 closefrom(sock + 1);
1623                 debug3("%s: [child] pid=%ld, exec %s",
1624                     __func__, (long)getpid(), _PATH_SSH_KEY_SIGN);
1625                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL);
1626                 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN,
1627                     strerror(errno));
1628         }
1629         close(from[1]);
1630         close(to[0]);
1631
1632         if ((b = sshbuf_new()) == NULL)
1633                 fatal("%s: sshbuf_new failed", __func__);
1634         /* send # of sock, data to be signed */
1635         if ((r = sshbuf_put_u32(b, sock) != 0) ||
1636             (r = sshbuf_put_string(b, data, datalen)) != 0)
1637                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1638         if (ssh_msg_send(to[1], version, b) == -1)
1639                 fatal("%s: couldn't send request", __func__);
1640         sshbuf_reset(b);
1641         r = ssh_msg_recv(from[0], b);
1642         close(from[0]);
1643         close(to[1]);
1644         if (r < 0) {
1645                 error("%s: no reply", __func__);
1646                 goto fail;
1647         }
1648
1649         errno = 0;
1650         while (waitpid(pid, &status, 0) < 0) {
1651                 if (errno != EINTR) {
1652                         error("%s: waitpid %ld: %s",
1653                             __func__, (long)pid, strerror(errno));
1654                         goto fail;
1655                 }
1656         }
1657         if (!WIFEXITED(status)) {
1658                 error("%s: exited abnormally", __func__);
1659                 goto fail;
1660         }
1661         if (WEXITSTATUS(status) != 0) {
1662                 error("%s: exited with status %d",
1663                     __func__, WEXITSTATUS(status));
1664                 goto fail;
1665         }
1666         if ((r = sshbuf_get_u8(b, &rversion)) != 0) {
1667                 error("%s: buffer error: %s", __func__, ssh_err(r));
1668                 goto fail;
1669         }
1670         if (rversion != version) {
1671                 error("%s: bad version", __func__);
1672                 goto fail;
1673         }
1674         if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) {
1675                 error("%s: buffer error: %s", __func__, ssh_err(r));
1676  fail:
1677                 signal(SIGCHLD, osigchld);
1678                 sshbuf_free(b);
1679                 return -1;
1680         }
1681         signal(SIGCHLD, osigchld);
1682         sshbuf_free(b);
1683
1684         return 0;
1685 }
1686
1687 int
1688 userauth_hostbased(Authctxt *authctxt)
1689 {
1690         struct ssh *ssh = active_state;
1691         struct sshkey *private = NULL;
1692         struct sshbuf *b = NULL;
1693         const char *service;
1694         u_char *sig = NULL, *keyblob = NULL;
1695         char *fp = NULL, *chost = NULL, *lname = NULL;
1696         size_t siglen = 0, keylen = 0;
1697         int i, r, success = 0;
1698
1699         if (authctxt->ktypes == NULL) {
1700                 authctxt->oktypes = xstrdup(options.hostbased_key_types);
1701                 authctxt->ktypes = authctxt->oktypes;
1702         }
1703
1704         /*
1705          * Work through each listed type pattern in HostbasedKeyTypes,
1706          * trying each hostkey that matches the type in turn.
1707          */
1708         for (;;) {
1709                 if (authctxt->active_ktype == NULL)
1710                         authctxt->active_ktype = strsep(&authctxt->ktypes, ",");
1711                 if (authctxt->active_ktype == NULL ||
1712                     *authctxt->active_ktype == '\0')
1713                         break;
1714                 debug3("%s: trying key type %s", __func__,
1715                     authctxt->active_ktype);
1716
1717                 /* check for a useful key */
1718                 private = NULL;
1719                 for (i = 0; i < authctxt->sensitive->nkeys; i++) {
1720                         if (authctxt->sensitive->keys[i] == NULL ||
1721                             authctxt->sensitive->keys[i]->type == KEY_RSA1 ||
1722                             authctxt->sensitive->keys[i]->type == KEY_UNSPEC)
1723                                 continue;
1724                         if (match_pattern_list(
1725                             sshkey_ssh_name(authctxt->sensitive->keys[i]),
1726                             authctxt->active_ktype, 0) != 1)
1727                                 continue;
1728                         /* we take and free the key */
1729                         private = authctxt->sensitive->keys[i];
1730                         authctxt->sensitive->keys[i] = NULL;
1731                         break;
1732                 }
1733                 /* Found one */
1734                 if (private != NULL)
1735                         break;
1736                 /* No more keys of this type; advance */
1737                 authctxt->active_ktype = NULL;
1738         }
1739         if (private == NULL) {
1740                 free(authctxt->oktypes);
1741                 authctxt->oktypes = authctxt->ktypes = NULL;
1742                 authctxt->active_ktype = NULL;
1743                 debug("No more client hostkeys for hostbased authentication.");
1744                 goto out;
1745         }
1746
1747         if ((fp = sshkey_fingerprint(private, options.fingerprint_hash,
1748             SSH_FP_DEFAULT)) == NULL) {
1749                 error("%s: sshkey_fingerprint failed", __func__);
1750                 goto out;
1751         }
1752         debug("%s: trying hostkey %s %s",
1753             __func__, sshkey_ssh_name(private), fp);
1754
1755         /* figure out a name for the client host */
1756         if ((lname = get_local_name(packet_get_connection_in())) == NULL) {
1757                 error("%s: cannot get local ipaddr/name", __func__);
1758                 goto out;
1759         }
1760
1761         /* XXX sshbuf_put_stringf? */
1762         xasprintf(&chost, "%s.", lname);
1763         debug2("%s: chost %s", __func__, chost);
1764
1765         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1766             authctxt->service;
1767
1768         /* construct data */
1769         if ((b = sshbuf_new()) == NULL) {
1770                 error("%s: sshbuf_new failed", __func__);
1771                 goto out;
1772         }
1773         if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) {
1774                 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r));
1775                 goto out;
1776         }
1777         if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 ||
1778             (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1779             (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
1780             (r = sshbuf_put_cstring(b, service)) != 0 ||
1781             (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
1782             (r = sshbuf_put_cstring(b, key_ssh_name(private))) != 0 ||
1783             (r = sshbuf_put_string(b, keyblob, keylen)) != 0 ||
1784             (r = sshbuf_put_cstring(b, chost)) != 0 ||
1785             (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) {
1786                 error("%s: buffer error: %s", __func__, ssh_err(r));
1787                 goto out;
1788         }
1789
1790 #ifdef DEBUG_PK
1791         sshbuf_dump(b, stderr);
1792 #endif
1793         if (authctxt->sensitive->external_keysign)
1794                 r = ssh_keysign(private, &sig, &siglen,
1795                     sshbuf_ptr(b), sshbuf_len(b));
1796         else if ((r = sshkey_sign(private, &sig, &siglen,
1797             sshbuf_ptr(b), sshbuf_len(b), NULL, datafellows)) != 0)
1798                 debug("%s: sshkey_sign: %s", __func__, ssh_err(r));
1799         if (r != 0) {
1800                 error("sign using hostkey %s %s failed",
1801                     sshkey_ssh_name(private), fp);
1802                 goto out;
1803         }
1804         if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1805             (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1806             (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1807             (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1808             (r = sshpkt_put_cstring(ssh, key_ssh_name(private))) != 0 ||
1809             (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 ||
1810             (r = sshpkt_put_cstring(ssh, chost)) != 0 ||
1811             (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 ||
1812             (r = sshpkt_put_string(ssh, sig, siglen)) != 0 ||
1813             (r = sshpkt_send(ssh)) != 0) {
1814                 error("%s: packet error: %s", __func__, ssh_err(r));
1815                 goto out;
1816         }
1817         success = 1;
1818
1819  out:
1820         if (sig != NULL) {
1821                 explicit_bzero(sig, siglen);
1822                 free(sig);
1823         }
1824         free(keyblob);
1825         free(lname);
1826         free(fp);
1827         free(chost);
1828         sshkey_free(private);
1829         sshbuf_free(b);
1830
1831         return success;
1832 }
1833
1834 /* find auth method */
1835
1836 /*
1837  * given auth method name, if configurable options permit this method fill
1838  * in auth_ident field and return true, otherwise return false.
1839  */
1840 static int
1841 authmethod_is_enabled(Authmethod *method)
1842 {
1843         if (method == NULL)
1844                 return 0;
1845         /* return false if options indicate this method is disabled */
1846         if  (method->enabled == NULL || *method->enabled == 0)
1847                 return 0;
1848         /* return false if batch mode is enabled but method needs interactive mode */
1849         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1850                 return 0;
1851         return 1;
1852 }
1853
1854 static Authmethod *
1855 authmethod_lookup(const char *name)
1856 {
1857         Authmethod *method = NULL;
1858         if (name != NULL)
1859                 for (method = authmethods; method->name != NULL; method++)
1860                         if (strcmp(name, method->name) == 0)
1861                                 return method;
1862         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1863         return NULL;
1864 }
1865
1866 /* XXX internal state */
1867 static Authmethod *current = NULL;
1868 static char *supported = NULL;
1869 static char *preferred = NULL;
1870
1871 /*
1872  * Given the authentication method list sent by the server, return the
1873  * next method we should try.  If the server initially sends a nil list,
1874  * use a built-in default list.
1875  */
1876 static Authmethod *
1877 authmethod_get(char *authlist)
1878 {
1879         char *name = NULL;
1880         u_int next;
1881
1882         /* Use a suitable default if we're passed a nil list.  */
1883         if (authlist == NULL || strlen(authlist) == 0)
1884                 authlist = options.preferred_authentications;
1885
1886         if (supported == NULL || strcmp(authlist, supported) != 0) {
1887                 debug3("start over, passed a different list %s", authlist);
1888                 free(supported);
1889                 supported = xstrdup(authlist);
1890                 preferred = options.preferred_authentications;
1891                 debug3("preferred %s", preferred);
1892                 current = NULL;
1893         } else if (current != NULL && authmethod_is_enabled(current))
1894                 return current;
1895
1896         for (;;) {
1897                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1898                         debug("No more authentication methods to try.");
1899                         current = NULL;
1900                         return NULL;
1901                 }
1902                 preferred += next;
1903                 debug3("authmethod_lookup %s", name);
1904                 debug3("remaining preferred: %s", preferred);
1905                 if ((current = authmethod_lookup(name)) != NULL &&
1906                     authmethod_is_enabled(current)) {
1907                         debug3("authmethod_is_enabled %s", name);
1908                         debug("Next authentication method: %s", name);
1909                         free(name);
1910                         return current;
1911                 }
1912                 free(name);
1913         }
1914 }
1915
1916 static char *
1917 authmethods_get(void)
1918 {
1919         Authmethod *method = NULL;
1920         Buffer b;
1921         char *list;
1922
1923         buffer_init(&b);
1924         for (method = authmethods; method->name != NULL; method++) {
1925                 if (authmethod_is_enabled(method)) {
1926                         if (buffer_len(&b) > 0)
1927                                 buffer_append(&b, ",", 1);
1928                         buffer_append(&b, method->name, strlen(method->name));
1929                 }
1930         }
1931         if ((list = sshbuf_dup_string(&b)) == NULL)
1932                 fatal("%s: sshbuf_dup_string failed", __func__);
1933         buffer_free(&b);
1934         return list;
1935 }
1936