crypto/openssh/sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.192 2013/02/17 23:16:57 dtucker Exp $ */
   2 /* $FreeBSD$ */
   3 /*
   4  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   5  * Copyright (c) 2008 Damien Miller.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 #include "includes.h"
  29
  30 #include <sys/types.h>
  31 #include <sys/socket.h>
  32 #include <sys/wait.h>
  33 #include <sys/stat.h>
  34
  35 #include <errno.h>
  36 #include <fcntl.h>
  37 #include <netdb.h>
  38 #include <pwd.h>
  39 #include <signal.h>
  40 #include <stdarg.h>
  41 #include <stdio.h>
  42 #include <string.h>
  43 #include <unistd.h>
  44 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS)
  45 #include <vis.h>
  46 #endif
  47
  48 #include "openbsd-compat/sys-queue.h"
  49
  50 #include "xmalloc.h"
  51 #include "ssh.h"
  52 #include "ssh2.h"
  53 #include "buffer.h"
  54 #include "packet.h"
  55 #include "compat.h"
  56 #include "cipher.h"
  57 #include "key.h"
  58 #include "kex.h"
  59 #include "myproposal.h"
  60 #include "sshconnect.h"
  61 #include "authfile.h"
  62 #include "dh.h"
  63 #include "authfd.h"
  64 #include "log.h"
  65 #include "readconf.h"
  66 #include "misc.h"
  67 #include "match.h"
  68 #include "dispatch.h"
  69 #include "canohost.h"
  70 #include "msg.h"
  71 #include "pathnames.h"
  72 #include "uidswap.h"
  73 #include "hostfile.h"
  74 #include "schnorr.h"
  75 #include "jpake.h"
  76
  77 #ifdef GSSAPI
  78 #include "ssh-gss.h"
  79 #endif
  80
  81 /* import */
  82 extern char *client_version_string;
  83 extern char *server_version_string;
  84 extern Options options;
  85 #ifdef  NONE_CIPHER_ENABLED
  86 extern Kex *xxx_kex;
  87
  88 /*
  89  * tty_flag is set in ssh.c so we can use it here.  If set then prevent
  90  * the switch to the null cipher.
  91  */
  92
  93 extern int tty_flag;
  94 #endif
  95
  96 /*
  97  * SSH2 key exchange
  98  */
  99
 100 u_char *session_id2 = NULL;
 101 u_int session_id2_len = 0;
 102
 103 char *xxx_host;
 104 struct sockaddr *xxx_hostaddr;
 105
 106 Kex *xxx_kex = NULL;
 107
 108 static int
 109 verify_host_key_callback(Key *hostkey)
 110 {
 111         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
 112                 fatal("Host key verification failed.");
 113         return 0;
 114 }
 115
 116 static char *
 117 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
 118 {
 119         char *oavail, *avail, *first, *last, *alg, *hostname, *ret;
 120         size_t maxlen;
 121         struct hostkeys *hostkeys;
 122         int ktype;
 123         u_int i;
 124
 125         /* Find all hostkeys for this hostname */
 126         get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
 127         hostkeys = init_hostkeys();
 128         for (i = 0; i < options.num_user_hostfiles; i++)
 129                 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]);
 130         for (i = 0; i < options.num_system_hostfiles; i++)
 131                 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]);
 132
 133         oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG);
 134         maxlen = strlen(avail) + 1;
 135         first = xmalloc(maxlen);
 136         last = xmalloc(maxlen);
 137         *first = *last = '\0';
 138
 139 #define ALG_APPEND(to, from) \
 140         do { \
 141                 if (*to != '\0') \
 142                         strlcat(to, ",", maxlen); \
 143                 strlcat(to, from, maxlen); \
 144         } while (0)
 145
 146         while ((alg = strsep(&avail, ",")) && *alg != '\0') {
 147                 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC)
 148                         fatal("%s: unknown alg %s", __func__, alg);
 149                 if (lookup_key_in_hostkeys_by_type(hostkeys,
 150                     key_type_plain(ktype), NULL))
 151                         ALG_APPEND(first, alg);
 152                 else
 153                         ALG_APPEND(last, alg);
 154         }
 155 #undef ALG_APPEND
 156         xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last);
 157         if (*first != '\0')
 158                 debug3("%s: prefer hostkeyalgs: %s", __func__, first);
 159
 160         xfree(first);
 161         xfree(last);
 162         xfree(hostname);
 163         xfree(oavail);
 164         free_hostkeys(hostkeys);
 165
 166         return ret;
 167 }
 168
 169 void
 170 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
 171 {
 172         Kex *kex;
 173
 174         xxx_host = host;
 175         xxx_hostaddr = hostaddr;
 176
 177         if (options.ciphers == (char *)-1) {
 178                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 179                 options.ciphers = NULL;
 180         }
 181         if (options.ciphers != NULL) {
 182                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 183                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 184         }
 185         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 186             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 187         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 188             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 189         if (options.compression) {
 190                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 191                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 192         } else {
 193                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 194                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 195         }
 196         if (options.macs != NULL) {
 197                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 198                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 199         }
 200         if (options.hostkeyalgorithms != NULL)
 201                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 202                     options.hostkeyalgorithms;
 203         else {
 204                 /* Prefer algorithms that we already have keys for */
 205                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 206                     order_hostkeyalgs(host, hostaddr, port);
 207         }
 208         if (options.kex_algorithms != NULL)
 209                 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
 210
 211         if (options.rekey_limit)
 212                 packet_set_rekey_limit((u_int32_t)options.rekey_limit);
 213
 214         /* start key exchange */
 215         kex = kex_setup(myproposal);
 216         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 217         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 218         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 219         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 220         kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
 221         kex->client_version_string=client_version_string;
 222         kex->server_version_string=server_version_string;
 223         kex->verify_host_key=&verify_host_key_callback;
 224
 225         xxx_kex = kex;
 226
 227         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 228
 229         if (options.use_roaming && !kex->roaming) {
 230                 debug("Roaming not allowed by server");
 231                 options.use_roaming = 0;
 232         }
 233
 234         session_id2 = kex->session_id;
 235         session_id2_len = kex->session_id_len;
 236
 237 #ifdef DEBUG_KEXDH
 238         /* send 1st encrypted/maced/compressed message */
 239         packet_start(SSH2_MSG_IGNORE);
 240         packet_put_cstring("markus");
 241         packet_send();
 242         packet_write_wait();
 243 #endif
 244 }
 245
 246 /*
 247  * Authenticate user
 248  */
 249
 250 typedef struct Authctxt Authctxt;
 251 typedef struct Authmethod Authmethod;
 252 typedef struct identity Identity;
 253 typedef struct idlist Idlist;
 254
 255 struct identity {
 256         TAILQ_ENTRY(identity) next;
 257         AuthenticationConnection *ac;   /* set if agent supports key */
 258         Key     *key;                   /* public/private key */
 259         char    *filename;              /* comment for agent-only keys */
 260         int     tried;
 261         int     isprivate;              /* key points to the private key */
 262         int     userprovided;
 263 };
 264 TAILQ_HEAD(idlist, identity);
 265
 266 struct Authctxt {
 267         const char *server_user;
 268         const char *local_user;
 269         const char *host;
 270         const char *service;
 271         Authmethod *method;
 272         sig_atomic_t success;
 273         char *authlist;
 274         /* pubkey */
 275         Idlist keys;
 276         AuthenticationConnection *agent;
 277         /* hostbased */
 278         Sensitive *sensitive;
 279         /* kbd-interactive */
 280         int info_req_seen;
 281         /* generic */
 282         void *methoddata;
 283 };
 284 struct Authmethod {
 285         char    *name;          /* string to compare against server's list */
 286         int     (*userauth)(Authctxt *authctxt);
 287         void    (*cleanup)(Authctxt *authctxt);
 288         int     *enabled;       /* flag in option struct that enables method */
 289         int     *batch_flag;    /* flag in option struct that disables method */
 290 };
 291
 292 void    input_userauth_success(int, u_int32_t, void *);
 293 void    input_userauth_success_unexpected(int, u_int32_t, void *);
 294 void    input_userauth_failure(int, u_int32_t, void *);
 295 void    input_userauth_banner(int, u_int32_t, void *);
 296 void    input_userauth_error(int, u_int32_t, void *);
 297 void    input_userauth_info_req(int, u_int32_t, void *);
 298 void    input_userauth_pk_ok(int, u_int32_t, void *);
 299 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 300 void    input_userauth_jpake_server_step1(int, u_int32_t, void *);
 301 void    input_userauth_jpake_server_step2(int, u_int32_t, void *);
 302 void    input_userauth_jpake_server_confirm(int, u_int32_t, void *);
 303
 304 int     userauth_none(Authctxt *);
 305 int     userauth_pubkey(Authctxt *);
 306 int     userauth_passwd(Authctxt *);
 307 int     userauth_kbdint(Authctxt *);
 308 int     userauth_hostbased(Authctxt *);
 309 int     userauth_jpake(Authctxt *);
 310
 311 void    userauth_jpake_cleanup(Authctxt *);
 312
 313 #ifdef GSSAPI
 314 int     userauth_gssapi(Authctxt *authctxt);
 315 void    input_gssapi_response(int type, u_int32_t, void *);
 316 void    input_gssapi_token(int type, u_int32_t, void *);
 317 void    input_gssapi_hash(int type, u_int32_t, void *);
 318 void    input_gssapi_error(int, u_int32_t, void *);
 319 void    input_gssapi_errtok(int, u_int32_t, void *);
 320 #endif
 321
 322 void    userauth(Authctxt *, char *);
 323
 324 static int sign_and_send_pubkey(Authctxt *, Identity *);
 325 static void pubkey_prepare(Authctxt *);
 326 static void pubkey_cleanup(Authctxt *);
 327 static Key *load_identity_file(char *, int);
 328
 329 static Authmethod *authmethod_get(char *authlist);
 330 static Authmethod *authmethod_lookup(const char *name);
 331 static char *authmethods_get(void);
 332
 333 Authmethod authmethods[] = {
 334 #ifdef GSSAPI
 335         {"gssapi-with-mic",
 336                 userauth_gssapi,
 337                 NULL,
 338                 &options.gss_authentication,
 339                 NULL},
 340 #endif
 341         {"hostbased",
 342                 userauth_hostbased,
 343                 NULL,
 344                 &options.hostbased_authentication,
 345                 NULL},
 346         {"publickey",
 347                 userauth_pubkey,
 348                 NULL,
 349                 &options.pubkey_authentication,
 350                 NULL},
 351 #ifdef JPAKE
 352         {"jpake-01@openssh.com",
 353                 userauth_jpake,
 354                 userauth_jpake_cleanup,
 355                 &options.zero_knowledge_password_authentication,
 356                 &options.batch_mode},
 357 #endif
 358         {"keyboard-interactive",
 359                 userauth_kbdint,
 360                 NULL,
 361                 &options.kbd_interactive_authentication,
 362                 &options.batch_mode},
 363         {"password",
 364                 userauth_passwd,
 365                 NULL,
 366                 &options.password_authentication,
 367                 &options.batch_mode},
 368         {"none",
 369                 userauth_none,
 370                 NULL,
 371                 NULL,
 372                 NULL},
 373         {NULL, NULL, NULL, NULL, NULL}
 374 };
 375
 376 void
 377 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 378     Sensitive *sensitive)
 379 {
 380         Authctxt authctxt;
 381         int type;
 382
 383         if (options.challenge_response_authentication)
 384                 options.kbd_interactive_authentication = 1;
 385
 386         packet_start(SSH2_MSG_SERVICE_REQUEST);
 387         packet_put_cstring("ssh-userauth");
 388         packet_send();
 389         debug("SSH2_MSG_SERVICE_REQUEST sent");
 390         packet_write_wait();
 391         type = packet_read();
 392         if (type != SSH2_MSG_SERVICE_ACCEPT)
 393                 fatal("Server denied authentication request: %d", type);
 394         if (packet_remaining() > 0) {
 395                 char *reply = packet_get_string(NULL);
 396                 debug2("service_accept: %s", reply);
 397                 xfree(reply);
 398         } else {
 399                 debug2("buggy server: service_accept w/o service");
 400         }
 401         packet_check_eom();
 402         debug("SSH2_MSG_SERVICE_ACCEPT received");
 403
 404         if (options.preferred_authentications == NULL)
 405                 options.preferred_authentications = authmethods_get();
 406
 407         /* setup authentication context */
 408         memset(&authctxt, 0, sizeof(authctxt));
 409         pubkey_prepare(&authctxt);
 410         authctxt.server_user = server_user;
 411         authctxt.local_user = local_user;
 412         authctxt.host = host;
 413         authctxt.service = "ssh-connection";            /* service name */
 414         authctxt.success = 0;
 415         authctxt.method = authmethod_lookup("none");
 416         authctxt.authlist = NULL;
 417         authctxt.methoddata = NULL;
 418         authctxt.sensitive = sensitive;
 419         authctxt.info_req_seen = 0;
 420         if (authctxt.method == NULL)
 421                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 422
 423         /* initial userauth request */
 424         userauth_none(&authctxt);
 425
 426         dispatch_init(&input_userauth_error);
 427         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 428         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 429         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 430         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 431
 432         pubkey_cleanup(&authctxt);
 433         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 434
 435 #ifdef  NONE_CIPHER_ENABLED
 436         /*
 437          * If the user explicitly requests to use the none cipher enable it
 438          * post authentication and only if the right conditions are met: both
 439          * of the NONE switches must be true and there must be no tty allocated.
 440          */
 441         if (options.none_switch == 1 && options.none_enabled == 1) {
 442                 if (!tty_flag) {
 443                         debug("Requesting none cipher re-keying...");
 444                         myproposal[PROPOSAL_ENC_ALGS_STOC] = "none";
 445                         myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none";
 446                         kex_prop2buf(&xxx_kex->my, myproposal);
 447                         packet_request_rekeying();
 448                         fprintf(stderr, "WARNING: enabled NONE cipher\n");
 449                 } else {
 450                         /* Requested NONE cipher on an interactive session. */
 451                         debug("Cannot switch to NONE cipher with tty "
 452                             "allocated");
 453                         fprintf(stderr, "NONE cipher switch disabled given "
 454                             "a TTY is allocated\n");
 455                 }
 456         }
 457 #endif
 458         debug("Authentication succeeded (%s).", authctxt.method->name);
 459 }
 460
 461 void
 462 userauth(Authctxt *authctxt, char *authlist)
 463 {
 464         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 465                 authctxt->method->cleanup(authctxt);
 466
 467         if (authctxt->methoddata) {
 468                 xfree(authctxt->methoddata);
 469                 authctxt->methoddata = NULL;
 470         }
 471         if (authlist == NULL) {
 472                 authlist = authctxt->authlist;
 473         } else {
 474                 if (authctxt->authlist)
 475                         xfree(authctxt->authlist);
 476                 authctxt->authlist = authlist;
 477         }
 478         for (;;) {
 479                 Authmethod *method = authmethod_get(authlist);
 480                 if (method == NULL)
 481                         fatal("Permission denied (%s).", authlist);
 482                 authctxt->method = method;
 483
 484                 /* reset the per method handler */
 485                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 486                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 487
 488                 /* and try new method */
 489                 if (method->userauth(authctxt) != 0) {
 490                         debug2("we sent a %s packet, wait for reply", method->name);
 491                         break;
 492                 } else {
 493                         debug2("we did not send a packet, disable method");
 494                         method->enabled = NULL;
 495                 }
 496         }
 497 }
 498
 499 /* ARGSUSED */
 500 void
 501 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 502 {
 503         fatal("input_userauth_error: bad message during authentication: "
 504             "type %d", type);
 505 }
 506
 507 /* ARGSUSED */
 508 void
 509 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 510 {
 511         char *msg, *raw, *lang;
 512         u_int len;
 513
 514         debug3("input_userauth_banner");
 515         raw = packet_get_string(&len);
 516         lang = packet_get_string(NULL);
 517         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
 518                 if (len > 65536)
 519                         len = 65536;
 520                 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
 521                 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH);
 522                 fprintf(stderr, "%s", msg);
 523                 xfree(msg);
 524         }
 525         xfree(raw);
 526         xfree(lang);
 527 }
 528
 529 /* ARGSUSED */
 530 void
 531 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 532 {
 533         Authctxt *authctxt = ctxt;
 534
 535         if (authctxt == NULL)
 536                 fatal("input_userauth_success: no authentication context");
 537         if (authctxt->authlist) {
 538                 xfree(authctxt->authlist);
 539                 authctxt->authlist = NULL;
 540         }
 541         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 542                 authctxt->method->cleanup(authctxt);
 543         if (authctxt->methoddata) {
 544                 xfree(authctxt->methoddata);
 545                 authctxt->methoddata = NULL;
 546         }
 547         authctxt->success = 1;                  /* break out */
 548 }
 549
 550 void
 551 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
 552 {
 553         Authctxt *authctxt = ctxt;
 554
 555         if (authctxt == NULL)
 556                 fatal("%s: no authentication context", __func__);
 557
 558         fatal("Unexpected authentication success during %s.",
 559             authctxt->method->name);
 560 }
 561
 562 /* ARGSUSED */
 563 void
 564 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 565 {
 566         Authctxt *authctxt = ctxt;
 567         char *authlist = NULL;
 568         int partial;
 569
 570         if (authctxt == NULL)
 571                 fatal("input_userauth_failure: no authentication context");
 572
 573         authlist = packet_get_string(NULL);
 574         partial = packet_get_char();
 575         packet_check_eom();
 576
 577         if (partial != 0)
 578                 logit("Authenticated with partial success.");
 579         debug("Authentications that can continue: %s", authlist);
 580
 581         userauth(authctxt, authlist);
 582 }
 583
 584 /* ARGSUSED */
 585 void
 586 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 587 {
 588         Authctxt *authctxt = ctxt;
 589         Key *key = NULL;
 590         Identity *id = NULL;
 591         Buffer b;
 592         int pktype, sent = 0;
 593         u_int alen, blen;
 594         char *pkalg, *fp;
 595         u_char *pkblob;
 596
 597         if (authctxt == NULL)
 598                 fatal("input_userauth_pk_ok: no authentication context");
 599         if (datafellows & SSH_BUG_PKOK) {
 600                 /* this is similar to SSH_BUG_PKAUTH */
 601                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 602                 pkblob = packet_get_string(&blen);
 603                 buffer_init(&b);
 604                 buffer_append(&b, pkblob, blen);
 605                 pkalg = buffer_get_string(&b, &alen);
 606                 buffer_free(&b);
 607         } else {
 608                 pkalg = packet_get_string(&alen);
 609                 pkblob = packet_get_string(&blen);
 610         }
 611         packet_check_eom();
 612
 613         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 614
 615         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 616                 debug("unknown pkalg %s", pkalg);
 617                 goto done;
 618         }
 619         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 620                 debug("no key from blob. pkalg %s", pkalg);
 621                 goto done;
 622         }
 623         if (key->type != pktype) {
 624                 error("input_userauth_pk_ok: type mismatch "
 625                     "for decoded key (received %d, expected %d)",
 626                     key->type, pktype);
 627                 goto done;
 628         }
 629         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 630         debug2("input_userauth_pk_ok: fp %s", fp);
 631         xfree(fp);
 632
 633         /*
 634          * search keys in the reverse order, because last candidate has been
 635          * moved to the end of the queue.  this also avoids confusion by
 636          * duplicate keys
 637          */
 638         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 639                 if (key_equal(key, id->key)) {
 640                         sent = sign_and_send_pubkey(authctxt, id);
 641                         break;
 642                 }
 643         }
 644 done:
 645         if (key != NULL)
 646                 key_free(key);
 647         xfree(pkalg);
 648         xfree(pkblob);
 649
 650         /* try another method if we did not send a packet */
 651         if (sent == 0)
 652                 userauth(authctxt, NULL);
 653 }
 654
 655 #ifdef GSSAPI
 656 int
 657 userauth_gssapi(Authctxt *authctxt)
 658 {
 659         Gssctxt *gssctxt = NULL;
 660         static gss_OID_set gss_supported = NULL;
 661         static u_int mech = 0;
 662         OM_uint32 min;
 663         int ok = 0;
 664
 665         /* Try one GSSAPI method at a time, rather than sending them all at
 666          * once. */
 667
 668         if (gss_supported == NULL)
 669                 gss_indicate_mechs(&min, &gss_supported);
 670
 671         /* Check to see if the mechanism is usable before we offer it */
 672         while (mech < gss_supported->count && !ok) {
 673                 /* My DER encoding requires length<128 */
 674                 if (gss_supported->elements[mech].length < 128 &&
 675                     ssh_gssapi_check_mechanism(&gssctxt,
 676                     &gss_supported->elements[mech], authctxt->host)) {
 677                         ok = 1; /* Mechanism works */
 678                 } else {
 679                         mech++;
 680                 }
 681         }
 682
 683         if (!ok)
 684                 return 0;
 685
 686         authctxt->methoddata=(void *)gssctxt;
 687
 688         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 689         packet_put_cstring(authctxt->server_user);
 690         packet_put_cstring(authctxt->service);
 691         packet_put_cstring(authctxt->method->name);
 692
 693         packet_put_int(1);
 694
 695         packet_put_int((gss_supported->elements[mech].length) + 2);
 696         packet_put_char(SSH_GSS_OIDTYPE);
 697         packet_put_char(gss_supported->elements[mech].length);
 698         packet_put_raw(gss_supported->elements[mech].elements,
 699             gss_supported->elements[mech].length);
 700
 701         packet_send();
 702
 703         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 704         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 705         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 706         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 707
 708         mech++; /* Move along to next candidate */
 709
 710         return 1;
 711 }
 712
 713 static OM_uint32
 714 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 715 {
 716         Authctxt *authctxt = ctxt;
 717         Gssctxt *gssctxt = authctxt->methoddata;
 718         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 719         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 720         gss_buffer_desc gssbuf;
 721         OM_uint32 status, ms, flags;
 722         Buffer b;
 723
 724         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 725             recv_tok, &send_tok, &flags);
 726
 727         if (send_tok.length > 0) {
 728                 if (GSS_ERROR(status))
 729                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 730                 else
 731                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 732
 733                 packet_put_string(send_tok.value, send_tok.length);
 734                 packet_send();
 735                 gss_release_buffer(&ms, &send_tok);
 736         }
 737
 738         if (status == GSS_S_COMPLETE) {
 739                 /* send either complete or MIC, depending on mechanism */
 740                 if (!(flags & GSS_C_INTEG_FLAG)) {
 741                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 742                         packet_send();
 743                 } else {
 744                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 745                             authctxt->service, "gssapi-with-mic");
 746
 747                         gssbuf.value = buffer_ptr(&b);
 748                         gssbuf.length = buffer_len(&b);
 749
 750                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 751
 752                         if (!GSS_ERROR(status)) {
 753                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 754                                 packet_put_string(mic.value, mic.length);
 755
 756                                 packet_send();
 757                         }
 758
 759                         buffer_free(&b);
 760                         gss_release_buffer(&ms, &mic);
 761                 }
 762         }
 763
 764         return status;
 765 }
 766
 767 /* ARGSUSED */
 768 void
 769 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 770 {
 771         Authctxt *authctxt = ctxt;
 772         Gssctxt *gssctxt;
 773         int oidlen;
 774         char *oidv;
 775
 776         if (authctxt == NULL)
 777                 fatal("input_gssapi_response: no authentication context");
 778         gssctxt = authctxt->methoddata;
 779
 780         /* Setup our OID */
 781         oidv = packet_get_string(&oidlen);
 782
 783         if (oidlen <= 2 ||
 784             oidv[0] != SSH_GSS_OIDTYPE ||
 785             oidv[1] != oidlen - 2) {
 786                 xfree(oidv);
 787                 debug("Badly encoded mechanism OID received");
 788                 userauth(authctxt, NULL);
 789                 return;
 790         }
 791
 792         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 793                 fatal("Server returned different OID than expected");
 794
 795         packet_check_eom();
 796
 797         xfree(oidv);
 798
 799         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 800                 /* Start again with next method on list */
 801                 debug("Trying to start again");
 802                 userauth(authctxt, NULL);
 803                 return;
 804         }
 805 }
 806
 807 /* ARGSUSED */
 808 void
 809 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 810 {
 811         Authctxt *authctxt = ctxt;
 812         gss_buffer_desc recv_tok;
 813         OM_uint32 status;
 814         u_int slen;
 815
 816         if (authctxt == NULL)
 817                 fatal("input_gssapi_response: no authentication context");
 818
 819         recv_tok.value = packet_get_string(&slen);
 820         recv_tok.length = slen; /* safe typecast */
 821
 822         packet_check_eom();
 823
 824         status = process_gssapi_token(ctxt, &recv_tok);
 825
 826         xfree(recv_tok.value);
 827
 828         if (GSS_ERROR(status)) {
 829                 /* Start again with the next method in the list */
 830                 userauth(authctxt, NULL);
 831                 return;
 832         }
 833 }
 834
 835 /* ARGSUSED */
 836 void
 837 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 838 {
 839         Authctxt *authctxt = ctxt;
 840         Gssctxt *gssctxt;
 841         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 842         gss_buffer_desc recv_tok;
 843         OM_uint32 status, ms;
 844         u_int len;
 845
 846         if (authctxt == NULL)
 847                 fatal("input_gssapi_response: no authentication context");
 848         gssctxt = authctxt->methoddata;
 849
 850         recv_tok.value = packet_get_string(&len);
 851         recv_tok.length = len;
 852
 853         packet_check_eom();
 854
 855         /* Stick it into GSSAPI and see what it says */
 856         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 857             &recv_tok, &send_tok, NULL);
 858
 859         xfree(recv_tok.value);
 860         gss_release_buffer(&ms, &send_tok);
 861
 862         /* Server will be returning a failed packet after this one */
 863 }
 864
 865 /* ARGSUSED */
 866 void
 867 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 868 {
 869         OM_uint32 maj, min;
 870         char *msg;
 871         char *lang;
 872
 873         maj=packet_get_int();
 874         min=packet_get_int();
 875         msg=packet_get_string(NULL);
 876         lang=packet_get_string(NULL);
 877
 878         packet_check_eom();
 879
 880         debug("Server GSSAPI Error:\n%s", msg);
 881         xfree(msg);
 882         xfree(lang);
 883 }
 884 #endif /* GSSAPI */
 885
 886 int
 887 userauth_none(Authctxt *authctxt)
 888 {
 889         /* initial userauth request */
 890         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 891         packet_put_cstring(authctxt->server_user);
 892         packet_put_cstring(authctxt->service);
 893         packet_put_cstring(authctxt->method->name);
 894         packet_send();
 895         return 1;
 896 }
 897
 898 int
 899 userauth_passwd(Authctxt *authctxt)
 900 {
 901         static int attempt = 0;
 902         char prompt[150];
 903         char *password;
 904         const char *host = options.host_key_alias ?  options.host_key_alias :
 905             authctxt->host;
 906
 907         if (attempt++ >= options.number_of_password_prompts)
 908                 return 0;
 909
 910         if (attempt != 1)
 911                 error("Permission denied, please try again.");
 912
 913         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 914             authctxt->server_user, host);
 915         password = read_passphrase(prompt, 0);
 916         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 917         packet_put_cstring(authctxt->server_user);
 918         packet_put_cstring(authctxt->service);
 919         packet_put_cstring(authctxt->method->name);
 920         packet_put_char(0);
 921         packet_put_cstring(password);
 922         memset(password, 0, strlen(password));
 923         xfree(password);
 924         packet_add_padding(64);
 925         packet_send();
 926
 927         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 928             &input_userauth_passwd_changereq);
 929
 930         return 1;
 931 }
 932
 933 /*
 934  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 935  */
 936 /* ARGSUSED */
 937 void
 938 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 939 {
 940         Authctxt *authctxt = ctxt;
 941         char *info, *lang, *password = NULL, *retype = NULL;
 942         char prompt[150];
 943         const char *host = options.host_key_alias ? options.host_key_alias :
 944             authctxt->host;
 945
 946         debug2("input_userauth_passwd_changereq");
 947
 948         if (authctxt == NULL)
 949                 fatal("input_userauth_passwd_changereq: "
 950                     "no authentication context");
 951
 952         info = packet_get_string(NULL);
 953         lang = packet_get_string(NULL);
 954         if (strlen(info) > 0)
 955                 logit("%s", info);
 956         xfree(info);
 957         xfree(lang);
 958         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 959         packet_put_cstring(authctxt->server_user);
 960         packet_put_cstring(authctxt->service);
 961         packet_put_cstring(authctxt->method->name);
 962         packet_put_char(1);                     /* additional info */
 963         snprintf(prompt, sizeof(prompt),
 964             "Enter %.30s@%.128s's old password: ",
 965             authctxt->server_user, host);
 966         password = read_passphrase(prompt, 0);
 967         packet_put_cstring(password);
 968         memset(password, 0, strlen(password));
 969         xfree(password);
 970         password = NULL;
 971         while (password == NULL) {
 972                 snprintf(prompt, sizeof(prompt),
 973                     "Enter %.30s@%.128s's new password: ",
 974                     authctxt->server_user, host);
 975                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 976                 if (password == NULL) {
 977                         /* bail out */
 978                         return;
 979                 }
 980                 snprintf(prompt, sizeof(prompt),
 981                     "Retype %.30s@%.128s's new password: ",
 982                     authctxt->server_user, host);
 983                 retype = read_passphrase(prompt, 0);
 984                 if (strcmp(password, retype) != 0) {
 985                         memset(password, 0, strlen(password));
 986                         xfree(password);
 987                         logit("Mismatch; try again, EOF to quit.");
 988                         password = NULL;
 989                 }
 990                 memset(retype, 0, strlen(retype));
 991                 xfree(retype);
 992         }
 993         packet_put_cstring(password);
 994         memset(password, 0, strlen(password));
 995         xfree(password);
 996         packet_add_padding(64);
 997         packet_send();
 998
 999         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
1000             &input_userauth_passwd_changereq);
1001 }
1002
1003 #ifdef JPAKE
1004 static char *
1005 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt)
1006 {
1007         /* OpenBSD crypt(3) handles all of these */
1008         if (strcmp(crypt_scheme, "crypt") == 0 ||
1009             strcmp(crypt_scheme, "bcrypt") == 0 ||
1010             strcmp(crypt_scheme, "md5crypt") == 0 ||
1011             strcmp(crypt_scheme, "crypt-extended") == 0)
1012                 return xstrdup(crypt(password, salt));
1013         error("%s: unsupported password encryption scheme \"%.100s\"",
1014             __func__, crypt_scheme);
1015         return NULL;
1016 }
1017
1018 static BIGNUM *
1019 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme,
1020     const char *salt)
1021 {
1022         char prompt[256], *password, *crypted;
1023         u_char *secret;
1024         u_int secret_len;
1025         BIGNUM *ret;
1026
1027         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ",
1028             authctxt->server_user, authctxt->host);
1029         password = read_passphrase(prompt, 0);
1030
1031         if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) {
1032                 logit("Disabling %s authentication", authctxt->method->name);
1033                 authctxt->method->enabled = NULL;
1034                 /* Continue with an empty password to fail gracefully */
1035                 crypted = xstrdup("");
1036         }
1037
1038 #ifdef JPAKE_DEBUG
1039         debug3("%s: salt = %s", __func__, salt);
1040         debug3("%s: scheme = %s", __func__, crypt_scheme);
1041         debug3("%s: crypted = %s", __func__, crypted);
1042 #endif
1043
1044         if (hash_buffer(crypted, strlen(crypted), EVP_sha256(),
1045             &secret, &secret_len) != 0)
1046                 fatal("%s: hash_buffer", __func__);
1047
1048         bzero(password, strlen(password));
1049         bzero(crypted, strlen(crypted));
1050         xfree(password);
1051         xfree(crypted);
1052
1053         if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL)
1054                 fatal("%s: BN_bin2bn (secret)", __func__);
1055         bzero(secret, secret_len);
1056         xfree(secret);
1057
1058         return ret;
1059 }
1060
1061 /* ARGSUSED */
1062 void
1063 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt)
1064 {
1065         Authctxt *authctxt = ctxt;
1066         struct jpake_ctx *pctx = authctxt->methoddata;
1067         u_char *x3_proof, *x4_proof, *x2_s_proof;
1068         u_int x3_proof_len, x4_proof_len, x2_s_proof_len;
1069         char *crypt_scheme, *salt;
1070
1071         /* Disable this message */
1072         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL);
1073
1074         if ((pctx->g_x3 = BN_new()) == NULL ||
1075             (pctx->g_x4 = BN_new()) == NULL)
1076                 fatal("%s: BN_new", __func__);
1077
1078         /* Fetch step 1 values */
1079         crypt_scheme = packet_get_string(NULL);
1080         salt = packet_get_string(NULL);
1081         pctx->server_id = packet_get_string(&pctx->server_id_len);
1082         packet_get_bignum2(pctx->g_x3);
1083         packet_get_bignum2(pctx->g_x4);
1084         x3_proof = packet_get_string(&x3_proof_len);
1085         x4_proof = packet_get_string(&x4_proof_len);
1086         packet_check_eom();
1087
1088         JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__));
1089
1090         /* Obtain password and derive secret */
1091         pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt);
1092         bzero(crypt_scheme, strlen(crypt_scheme));
1093         bzero(salt, strlen(salt));
1094         xfree(crypt_scheme);
1095         xfree(salt);
1096         JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__));
1097
1098         /* Calculate step 2 values */
1099         jpake_step2(pctx->grp, pctx->s, pctx->g_x1,
1100             pctx->g_x3, pctx->g_x4, pctx->x2,
1101             pctx->server_id, pctx->server_id_len,
1102             pctx->client_id, pctx->client_id_len,
1103             x3_proof, x3_proof_len,
1104             x4_proof, x4_proof_len,
1105             &pctx->a,
1106             &x2_s_proof, &x2_s_proof_len);
1107
1108         bzero(x3_proof, x3_proof_len);
1109         bzero(x4_proof, x4_proof_len);
1110         xfree(x3_proof);
1111         xfree(x4_proof);
1112
1113         JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__));
1114
1115         /* Send values for step 2 */
1116         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2);
1117         packet_put_bignum2(pctx->a);
1118         packet_put_string(x2_s_proof, x2_s_proof_len);
1119         packet_send();
1120
1121         bzero(x2_s_proof, x2_s_proof_len);
1122         xfree(x2_s_proof);
1123
1124         /* Expect step 2 packet from peer */
1125         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2,
1126             input_userauth_jpake_server_step2);
1127 }
1128
1129 /* ARGSUSED */
1130 void
1131 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt)
1132 {
1133         Authctxt *authctxt = ctxt;
1134         struct jpake_ctx *pctx = authctxt->methoddata;
1135         u_char *x4_s_proof;
1136         u_int x4_s_proof_len;
1137
1138         /* Disable this message */
1139         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL);
1140
1141         if ((pctx->b = BN_new()) == NULL)
1142                 fatal("%s: BN_new", __func__);
1143
1144         /* Fetch step 2 values */
1145         packet_get_bignum2(pctx->b);
1146         x4_s_proof = packet_get_string(&x4_s_proof_len);
1147         packet_check_eom();
1148
1149         JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__));
1150
1151         /* Derive shared key and calculate confirmation hash */
1152         jpake_key_confirm(pctx->grp, pctx->s, pctx->b,
1153             pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4,
1154             pctx->client_id, pctx->client_id_len,
1155             pctx->server_id, pctx->server_id_len,
1156             session_id2, session_id2_len,
1157             x4_s_proof, x4_s_proof_len,
1158             &pctx->k,
1159             &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len);
1160
1161         bzero(x4_s_proof, x4_s_proof_len);
1162         xfree(x4_s_proof);
1163
1164         JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__));
1165
1166         /* Send key confirmation proof */
1167         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM);
1168         packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len);
1169         packet_send();
1170
1171         /* Expect confirmation from peer */
1172         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM,
1173             input_userauth_jpake_server_confirm);
1174 }
1175
1176 /* ARGSUSED */
1177 void
1178 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt)
1179 {
1180         Authctxt *authctxt = ctxt;
1181         struct jpake_ctx *pctx = authctxt->methoddata;
1182
1183         /* Disable this message */
1184         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL);
1185
1186         pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len);
1187         packet_check_eom();
1188
1189         JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__));
1190
1191         /* Verify expected confirmation hash */
1192         if (jpake_check_confirm(pctx->k,
1193             pctx->server_id, pctx->server_id_len,
1194             session_id2, session_id2_len,
1195             pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1)
1196                 debug("%s: %s success", __func__, authctxt->method->name);
1197         else {
1198                 debug("%s: confirmation mismatch", __func__);
1199                 /* XXX stash this so if auth succeeds then we can warn/kill */
1200         }
1201
1202         userauth_jpake_cleanup(authctxt);
1203 }
1204 #endif /* JPAKE */
1205
1206 static int
1207 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
1208     u_char *data, u_int datalen)
1209 {
1210         Key *prv;
1211         int ret;
1212
1213         /* the agent supports this key */
1214         if (id->ac)
1215                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1216                     data, datalen));
1217         /*
1218          * we have already loaded the private key or
1219          * the private key is stored in external hardware
1220          */
1221         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1222                 return (key_sign(id->key, sigp, lenp, data, datalen));
1223         /* load the private key from the file */
1224         if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL)
1225                 return (-1);
1226         ret = key_sign(prv, sigp, lenp, data, datalen);
1227         key_free(prv);
1228         return (ret);
1229 }
1230
1231 static int
1232 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1233 {
1234         Buffer b;
1235         u_char *blob, *signature;
1236         u_int bloblen, slen;
1237         u_int skip = 0;
1238         int ret = -1;
1239         int have_sig = 1;
1240         char *fp;
1241
1242         fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
1243         debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp);
1244         xfree(fp);
1245
1246         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1247                 /* we cannot handle this key */
1248                 debug3("sign_and_send_pubkey: cannot handle key");
1249                 return 0;
1250         }
1251         /* data to be signed */
1252         buffer_init(&b);
1253         if (datafellows & SSH_OLD_SESSIONID) {
1254                 buffer_append(&b, session_id2, session_id2_len);
1255                 skip = session_id2_len;
1256         } else {
1257                 buffer_put_string(&b, session_id2, session_id2_len);
1258                 skip = buffer_len(&b);
1259         }
1260         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1261         buffer_put_cstring(&b, authctxt->server_user);
1262         buffer_put_cstring(&b,
1263             datafellows & SSH_BUG_PKSERVICE ?
1264             "ssh-userauth" :
1265             authctxt->service);
1266         if (datafellows & SSH_BUG_PKAUTH) {
1267                 buffer_put_char(&b, have_sig);
1268         } else {
1269                 buffer_put_cstring(&b, authctxt->method->name);
1270                 buffer_put_char(&b, have_sig);
1271                 buffer_put_cstring(&b, key_ssh_name(id->key));
1272         }
1273         buffer_put_string(&b, blob, bloblen);
1274
1275         /* generate signature */
1276         ret = identity_sign(id, &signature, &slen,
1277             buffer_ptr(&b), buffer_len(&b));
1278         if (ret == -1) {
1279                 xfree(blob);
1280                 buffer_free(&b);
1281                 return 0;
1282         }
1283 #ifdef DEBUG_PK
1284         buffer_dump(&b);
1285 #endif
1286         if (datafellows & SSH_BUG_PKSERVICE) {
1287                 buffer_clear(&b);
1288                 buffer_append(&b, session_id2, session_id2_len);
1289                 skip = session_id2_len;
1290                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1291                 buffer_put_cstring(&b, authctxt->server_user);
1292                 buffer_put_cstring(&b, authctxt->service);
1293                 buffer_put_cstring(&b, authctxt->method->name);
1294                 buffer_put_char(&b, have_sig);
1295                 if (!(datafellows & SSH_BUG_PKAUTH))
1296                         buffer_put_cstring(&b, key_ssh_name(id->key));
1297                 buffer_put_string(&b, blob, bloblen);
1298         }
1299         xfree(blob);
1300
1301         /* append signature */
1302         buffer_put_string(&b, signature, slen);
1303         xfree(signature);
1304
1305         /* skip session id and packet type */
1306         if (buffer_len(&b) < skip + 1)
1307                 fatal("userauth_pubkey: internal error");
1308         buffer_consume(&b, skip + 1);
1309
1310         /* put remaining data from buffer into packet */
1311         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1312         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1313         buffer_free(&b);
1314         packet_send();
1315
1316         return 1;
1317 }
1318
1319 static int
1320 send_pubkey_test(Authctxt *authctxt, Identity *id)
1321 {
1322         u_char *blob;
1323         u_int bloblen, have_sig = 0;
1324
1325         debug3("send_pubkey_test");
1326
1327         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1328                 /* we cannot handle this key */
1329                 debug3("send_pubkey_test: cannot handle key");
1330                 return 0;
1331         }
1332         /* register callback for USERAUTH_PK_OK message */
1333         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1334
1335         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1336         packet_put_cstring(authctxt->server_user);
1337         packet_put_cstring(authctxt->service);
1338         packet_put_cstring(authctxt->method->name);
1339         packet_put_char(have_sig);
1340         if (!(datafellows & SSH_BUG_PKAUTH))
1341                 packet_put_cstring(key_ssh_name(id->key));
1342         packet_put_string(blob, bloblen);
1343         xfree(blob);
1344         packet_send();
1345         return 1;
1346 }
1347
1348 static Key *
1349 load_identity_file(char *filename, int userprovided)
1350 {
1351         Key *private;
1352         char prompt[300], *passphrase;
1353         int perm_ok = 0, quit, i;
1354         struct stat st;
1355
1356         if (stat(filename, &st) < 0) {
1357                 (userprovided ? logit : debug3)("no such identity: %s: %s",
1358                     filename, strerror(errno));
1359                 return NULL;
1360         }
1361         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1362         if (!perm_ok)
1363                 return NULL;
1364         if (private == NULL) {
1365                 if (options.batch_mode)
1366                         return NULL;
1367                 snprintf(prompt, sizeof prompt,
1368                     "Enter passphrase for key '%.100s': ", filename);
1369                 for (i = 0; i < options.number_of_password_prompts; i++) {
1370                         passphrase = read_passphrase(prompt, 0);
1371                         if (strcmp(passphrase, "") != 0) {
1372                                 private = key_load_private_type(KEY_UNSPEC,
1373                                     filename, passphrase, NULL, NULL);
1374                                 quit = 0;
1375                         } else {
1376                                 debug2("no passphrase given, try next key");
1377                                 quit = 1;
1378                         }
1379                         memset(passphrase, 0, strlen(passphrase));
1380                         xfree(passphrase);
1381                         if (private != NULL || quit)
1382                                 break;
1383                         debug2("bad passphrase given, try again...");
1384                 }
1385         }
1386         return private;
1387 }
1388
1389 /*
1390  * try keys in the following order:
1391  *      1. agent keys that are found in the config file
1392  *      2. other agent keys
1393  *      3. keys that are only listed in the config file
1394  */
1395 static void
1396 pubkey_prepare(Authctxt *authctxt)
1397 {
1398         Identity *id, *id2, *tmp;
1399         Idlist agent, files, *preferred;
1400         Key *key;
1401         AuthenticationConnection *ac;
1402         char *comment;
1403         int i, found;
1404
1405         TAILQ_INIT(&agent);     /* keys from the agent */
1406         TAILQ_INIT(&files);     /* keys from the config file */
1407         preferred = &authctxt->keys;
1408         TAILQ_INIT(preferred);  /* preferred order of keys */
1409
1410         /* list of keys stored in the filesystem and PKCS#11 */
1411         for (i = 0; i < options.num_identity_files; i++) {
1412                 key = options.identity_keys[i];
1413                 if (key && key->type == KEY_RSA1)
1414                         continue;
1415                 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1416                         continue;
1417                 options.identity_keys[i] = NULL;
1418                 id = xcalloc(1, sizeof(*id));
1419                 id->key = key;
1420                 id->filename = xstrdup(options.identity_files[i]);
1421                 id->userprovided = options.identity_file_userprovided[i];
1422                 TAILQ_INSERT_TAIL(&files, id, next);
1423         }
1424         /* Prefer PKCS11 keys that are explicitly listed */
1425         TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1426                 if (id->key == NULL || (id->key->flags & KEY_FLAG_EXT) == 0)
1427                         continue;
1428                 found = 0;
1429                 TAILQ_FOREACH(id2, &files, next) {
1430                         if (id2->key == NULL ||
1431                             (id2->key->flags & KEY_FLAG_EXT) != 0)
1432                                 continue;
1433                         if (key_equal(id->key, id2->key)) {
1434                                 TAILQ_REMOVE(&files, id, next);
1435                                 TAILQ_INSERT_TAIL(preferred, id, next);
1436                                 found = 1;
1437                                 break;
1438                         }
1439                 }
1440                 /* If IdentitiesOnly set and key not found then don't use it */
1441                 if (!found && options.identities_only) {
1442                         TAILQ_REMOVE(&files, id, next);
1443                         bzero(id, sizeof(id));
1444                         free(id);
1445                 }
1446         }
1447         /* list of keys supported by the agent */
1448         if ((ac = ssh_get_authentication_connection())) {
1449                 for (key = ssh_get_first_identity(ac, &comment, 2);
1450                     key != NULL;
1451                     key = ssh_get_next_identity(ac, &comment, 2)) {
1452                         found = 0;
1453                         TAILQ_FOREACH(id, &files, next) {
1454                                 /* agent keys from the config file are preferred */
1455                                 if (key_equal(key, id->key)) {
1456                                         key_free(key);
1457                                         xfree(comment);
1458                                         TAILQ_REMOVE(&files, id, next);
1459                                         TAILQ_INSERT_TAIL(preferred, id, next);
1460                                         id->ac = ac;
1461                                         found = 1;
1462                                         break;
1463                                 }
1464                         }
1465                         if (!found && !options.identities_only) {
1466                                 id = xcalloc(1, sizeof(*id));
1467                                 id->key = key;
1468                                 id->filename = comment;
1469                                 id->ac = ac;
1470                                 TAILQ_INSERT_TAIL(&agent, id, next);
1471                         }
1472                 }
1473                 /* append remaining agent keys */
1474                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1475                         TAILQ_REMOVE(&agent, id, next);
1476                         TAILQ_INSERT_TAIL(preferred, id, next);
1477                 }
1478                 authctxt->agent = ac;
1479         }
1480         /* append remaining keys from the config file */
1481         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1482                 TAILQ_REMOVE(&files, id, next);
1483                 TAILQ_INSERT_TAIL(preferred, id, next);
1484         }
1485         TAILQ_FOREACH(id, preferred, next) {
1486                 debug2("key: %s (%p),%s", id->filename, id->key,
1487                     id->userprovided ? " explicit" : "");
1488         }
1489 }
1490
1491 static void
1492 pubkey_cleanup(Authctxt *authctxt)
1493 {
1494         Identity *id;
1495
1496         if (authctxt->agent != NULL)
1497                 ssh_close_authentication_connection(authctxt->agent);
1498         for (id = TAILQ_FIRST(&authctxt->keys); id;
1499             id = TAILQ_FIRST(&authctxt->keys)) {
1500                 TAILQ_REMOVE(&authctxt->keys, id, next);
1501                 if (id->key)
1502                         key_free(id->key);
1503                 if (id->filename)
1504                         xfree(id->filename);
1505                 xfree(id);
1506         }
1507 }
1508
1509 int
1510 userauth_pubkey(Authctxt *authctxt)
1511 {
1512         Identity *id;
1513         int sent = 0;
1514
1515         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1516                 if (id->tried++)
1517                         return (0);
1518                 /* move key to the end of the queue */
1519                 TAILQ_REMOVE(&authctxt->keys, id, next);
1520                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1521                 /*
1522                  * send a test message if we have the public key. for
1523                  * encrypted keys we cannot do this and have to load the
1524                  * private key instead
1525                  */
1526                 if (id->key && id->key->type != KEY_RSA1) {
1527                         debug("Offering %s public key: %s", key_type(id->key),
1528                             id->filename);
1529                         sent = send_pubkey_test(authctxt, id);
1530                 } else if (id->key == NULL) {
1531                         debug("Trying private key: %s", id->filename);
1532                         id->key = load_identity_file(id->filename,
1533                             id->userprovided);
1534                         if (id->key != NULL) {
1535                                 id->isprivate = 1;
1536                                 sent = sign_and_send_pubkey(authctxt, id);
1537                                 key_free(id->key);
1538                                 id->key = NULL;
1539                         }
1540                 }
1541                 if (sent)
1542                         return (sent);
1543         }
1544         return (0);
1545 }
1546
1547 /*
1548  * Send userauth request message specifying keyboard-interactive method.
1549  */
1550 int
1551 userauth_kbdint(Authctxt *authctxt)
1552 {
1553         static int attempt = 0;
1554
1555         if (attempt++ >= options.number_of_password_prompts)
1556                 return 0;
1557         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1558         if (attempt > 1 && !authctxt->info_req_seen) {
1559                 debug3("userauth_kbdint: disable: no info_req_seen");
1560                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1561                 return 0;
1562         }
1563
1564         debug2("userauth_kbdint");
1565         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1566         packet_put_cstring(authctxt->server_user);
1567         packet_put_cstring(authctxt->service);
1568         packet_put_cstring(authctxt->method->name);
1569         packet_put_cstring("");                                 /* lang */
1570         packet_put_cstring(options.kbd_interactive_devices ?
1571             options.kbd_interactive_devices : "");
1572         packet_send();
1573
1574         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1575         return 1;
1576 }
1577
1578 /*
1579  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1580  */
1581 void
1582 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1583 {
1584         Authctxt *authctxt = ctxt;
1585         char *name, *inst, *lang, *prompt, *response;
1586         u_int num_prompts, i;
1587         int echo = 0;
1588
1589         debug2("input_userauth_info_req");
1590
1591         if (authctxt == NULL)
1592                 fatal("input_userauth_info_req: no authentication context");
1593
1594         authctxt->info_req_seen = 1;
1595
1596         name = packet_get_string(NULL);
1597         inst = packet_get_string(NULL);
1598         lang = packet_get_string(NULL);
1599         if (strlen(name) > 0)
1600                 logit("%s", name);
1601         if (strlen(inst) > 0)
1602                 logit("%s", inst);
1603         xfree(name);
1604         xfree(inst);
1605         xfree(lang);
1606
1607         num_prompts = packet_get_int();
1608         /*
1609          * Begin to build info response packet based on prompts requested.
1610          * We commit to providing the correct number of responses, so if
1611          * further on we run into a problem that prevents this, we have to
1612          * be sure and clean this up and send a correct error response.
1613          */
1614         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1615         packet_put_int(num_prompts);
1616
1617         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1618         for (i = 0; i < num_prompts; i++) {
1619                 prompt = packet_get_string(NULL);
1620                 echo = packet_get_char();
1621
1622                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1623
1624                 packet_put_cstring(response);
1625                 memset(response, 0, strlen(response));
1626                 xfree(response);
1627                 xfree(prompt);
1628         }
1629         packet_check_eom(); /* done with parsing incoming message. */
1630
1631         packet_add_padding(64);
1632         packet_send();
1633 }
1634
1635 static int
1636 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1637     u_char *data, u_int datalen)
1638 {
1639         Buffer b;
1640         struct stat st;
1641         pid_t pid;
1642         int to[2], from[2], status, version = 2;
1643
1644         debug2("ssh_keysign called");
1645
1646         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1647                 error("ssh_keysign: not installed: %s", strerror(errno));
1648                 return -1;
1649         }
1650         if (fflush(stdout) != 0)
1651                 error("ssh_keysign: fflush: %s", strerror(errno));
1652         if (pipe(to) < 0) {
1653                 error("ssh_keysign: pipe: %s", strerror(errno));
1654                 return -1;
1655         }
1656         if (pipe(from) < 0) {
1657                 error("ssh_keysign: pipe: %s", strerror(errno));
1658                 return -1;
1659         }
1660         if ((pid = fork()) < 0) {
1661                 error("ssh_keysign: fork: %s", strerror(errno));
1662                 return -1;
1663         }
1664         if (pid == 0) {
1665                 /* keep the socket on exec */
1666                 fcntl(packet_get_connection_in(), F_SETFD, 0);
1667                 permanently_drop_suid(getuid());
1668                 close(from[0]);
1669                 if (dup2(from[1], STDOUT_FILENO) < 0)
1670                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1671                 close(to[1]);
1672                 if (dup2(to[0], STDIN_FILENO) < 0)
1673                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1674                 close(from[1]);
1675                 close(to[0]);
1676                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1677                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1678                     strerror(errno));
1679         }
1680         close(from[1]);
1681         close(to[0]);
1682
1683         buffer_init(&b);
1684         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1685         buffer_put_string(&b, data, datalen);
1686         if (ssh_msg_send(to[1], version, &b) == -1)
1687                 fatal("ssh_keysign: couldn't send request");
1688
1689         if (ssh_msg_recv(from[0], &b) < 0) {
1690                 error("ssh_keysign: no reply");
1691                 buffer_free(&b);
1692                 return -1;
1693         }
1694         close(from[0]);
1695         close(to[1]);
1696
1697         while (waitpid(pid, &status, 0) < 0)
1698                 if (errno != EINTR)
1699                         break;
1700
1701         if (buffer_get_char(&b) != version) {
1702                 error("ssh_keysign: bad version");
1703                 buffer_free(&b);
1704                 return -1;
1705         }
1706         *sigp = buffer_get_string(&b, lenp);
1707         buffer_free(&b);
1708
1709         return 0;
1710 }
1711
1712 int
1713 userauth_hostbased(Authctxt *authctxt)
1714 {
1715         Key *private = NULL;
1716         Sensitive *sensitive = authctxt->sensitive;
1717         Buffer b;
1718         u_char *signature, *blob;
1719         char *chost, *pkalg, *p;
1720         const char *service;
1721         u_int blen, slen;
1722         int ok, i, found = 0;
1723
1724         /* check for a useful key */
1725         for (i = 0; i < sensitive->nkeys; i++) {
1726                 private = sensitive->keys[i];
1727                 if (private && private->type != KEY_RSA1) {
1728                         found = 1;
1729                         /* we take and free the key */
1730                         sensitive->keys[i] = NULL;
1731                         break;
1732                 }
1733         }
1734         if (!found) {
1735                 debug("No more client hostkeys for hostbased authentication.");
1736                 return 0;
1737         }
1738         if (key_to_blob(private, &blob, &blen) == 0) {
1739                 key_free(private);
1740                 return 0;
1741         }
1742         /* figure out a name for the client host */
1743         p = get_local_name(packet_get_connection_in());
1744         if (p == NULL) {
1745                 error("userauth_hostbased: cannot get local ipaddr/name");
1746                 key_free(private);
1747                 xfree(blob);
1748                 return 0;
1749         }
1750         xasprintf(&chost, "%s.", p);
1751         debug2("userauth_hostbased: chost %s", chost);
1752         xfree(p);
1753
1754         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1755             authctxt->service;
1756         pkalg = xstrdup(key_ssh_name(private));
1757         buffer_init(&b);
1758         /* construct data */
1759         buffer_put_string(&b, session_id2, session_id2_len);
1760         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1761         buffer_put_cstring(&b, authctxt->server_user);
1762         buffer_put_cstring(&b, service);
1763         buffer_put_cstring(&b, authctxt->method->name);
1764         buffer_put_cstring(&b, pkalg);
1765         buffer_put_string(&b, blob, blen);
1766         buffer_put_cstring(&b, chost);
1767         buffer_put_cstring(&b, authctxt->local_user);
1768 #ifdef DEBUG_PK
1769         buffer_dump(&b);
1770 #endif
1771         if (sensitive->external_keysign)
1772                 ok = ssh_keysign(private, &signature, &slen,
1773                     buffer_ptr(&b), buffer_len(&b));
1774         else
1775                 ok = key_sign(private, &signature, &slen,
1776                     buffer_ptr(&b), buffer_len(&b));
1777         key_free(private);
1778         buffer_free(&b);
1779         if (ok != 0) {
1780                 error("key_sign failed");
1781                 xfree(chost);
1782                 xfree(pkalg);
1783                 xfree(blob);
1784                 return 0;
1785         }
1786         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1787         packet_put_cstring(authctxt->server_user);
1788         packet_put_cstring(authctxt->service);
1789         packet_put_cstring(authctxt->method->name);
1790         packet_put_cstring(pkalg);
1791         packet_put_string(blob, blen);
1792         packet_put_cstring(chost);
1793         packet_put_cstring(authctxt->local_user);
1794         packet_put_string(signature, slen);
1795         memset(signature, 's', slen);
1796         xfree(signature);
1797         xfree(chost);
1798         xfree(pkalg);
1799         xfree(blob);
1800
1801         packet_send();
1802         return 1;
1803 }
1804
1805 #ifdef JPAKE
1806 int
1807 userauth_jpake(Authctxt *authctxt)
1808 {
1809         struct jpake_ctx *pctx;
1810         u_char *x1_proof, *x2_proof;
1811         u_int x1_proof_len, x2_proof_len;
1812         static int attempt = 0; /* XXX share with userauth_password's? */
1813
1814         if (attempt++ >= options.number_of_password_prompts)
1815                 return 0;
1816         if (attempt != 1)
1817                 error("Permission denied, please try again.");
1818
1819         if (authctxt->methoddata != NULL)
1820                 fatal("%s: authctxt->methoddata already set (%p)",
1821                     __func__, authctxt->methoddata);
1822
1823         authctxt->methoddata = pctx = jpake_new();
1824
1825         /*
1826          * Send request immediately, to get the protocol going while
1827          * we do the initial computations.
1828          */
1829         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1830         packet_put_cstring(authctxt->server_user);
1831         packet_put_cstring(authctxt->service);
1832         packet_put_cstring(authctxt->method->name);
1833         packet_send();
1834         packet_write_wait();
1835
1836         jpake_step1(pctx->grp,
1837             &pctx->client_id, &pctx->client_id_len,
1838             &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2,
1839             &x1_proof, &x1_proof_len,
1840             &x2_proof, &x2_proof_len);
1841
1842         JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__));
1843
1844         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1);
1845         packet_put_string(pctx->client_id, pctx->client_id_len);
1846         packet_put_bignum2(pctx->g_x1);
1847         packet_put_bignum2(pctx->g_x2);
1848         packet_put_string(x1_proof, x1_proof_len);
1849         packet_put_string(x2_proof, x2_proof_len);
1850         packet_send();
1851
1852         bzero(x1_proof, x1_proof_len);
1853         bzero(x2_proof, x2_proof_len);
1854         xfree(x1_proof);
1855         xfree(x2_proof);
1856
1857         /* Expect step 1 packet from peer */
1858         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1,
1859             input_userauth_jpake_server_step1);
1860         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS,
1861             &input_userauth_success_unexpected);
1862
1863         return 1;
1864 }
1865
1866 void
1867 userauth_jpake_cleanup(Authctxt *authctxt)
1868 {
1869         debug3("%s: clean up", __func__);
1870         if (authctxt->methoddata != NULL) {
1871                 jpake_free(authctxt->methoddata);
1872                 authctxt->methoddata = NULL;
1873         }
1874         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
1875 }
1876 #endif /* JPAKE */
1877
1878 /* find auth method */
1879
1880 /*
1881  * given auth method name, if configurable options permit this method fill
1882  * in auth_ident field and return true, otherwise return false.
1883  */
1884 static int
1885 authmethod_is_enabled(Authmethod *method)
1886 {
1887         if (method == NULL)
1888                 return 0;
1889         /* return false if options indicate this method is disabled */
1890         if  (method->enabled == NULL || *method->enabled == 0)
1891                 return 0;
1892         /* return false if batch mode is enabled but method needs interactive mode */
1893         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1894                 return 0;
1895         return 1;
1896 }
1897
1898 static Authmethod *
1899 authmethod_lookup(const char *name)
1900 {
1901         Authmethod *method = NULL;
1902         if (name != NULL)
1903                 for (method = authmethods; method->name != NULL; method++)
1904                         if (strcmp(name, method->name) == 0)
1905                                 return method;
1906         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1907         return NULL;
1908 }
1909
1910 /* XXX internal state */
1911 static Authmethod *current = NULL;
1912 static char *supported = NULL;
1913 static char *preferred = NULL;
1914
1915 /*
1916  * Given the authentication method list sent by the server, return the
1917  * next method we should try.  If the server initially sends a nil list,
1918  * use a built-in default list.
1919  */
1920 static Authmethod *
1921 authmethod_get(char *authlist)
1922 {
1923         char *name = NULL;
1924         u_int next;
1925
1926         /* Use a suitable default if we're passed a nil list.  */
1927         if (authlist == NULL || strlen(authlist) == 0)
1928                 authlist = options.preferred_authentications;
1929
1930         if (supported == NULL || strcmp(authlist, supported) != 0) {
1931                 debug3("start over, passed a different list %s", authlist);
1932                 if (supported != NULL)
1933                         xfree(supported);
1934                 supported = xstrdup(authlist);
1935                 preferred = options.preferred_authentications;
1936                 debug3("preferred %s", preferred);
1937                 current = NULL;
1938         } else if (current != NULL && authmethod_is_enabled(current))
1939                 return current;
1940
1941         for (;;) {
1942                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1943                         debug("No more authentication methods to try.");
1944                         current = NULL;
1945                         return NULL;
1946                 }
1947                 preferred += next;
1948                 debug3("authmethod_lookup %s", name);
1949                 debug3("remaining preferred: %s", preferred);
1950                 if ((current = authmethod_lookup(name)) != NULL &&
1951                     authmethod_is_enabled(current)) {
1952                         debug3("authmethod_is_enabled %s", name);
1953                         debug("Next authentication method: %s", name);
1954                         xfree(name);
1955                         return current;
1956                 }
1957         }
1958 }
1959
1960 static char *
1961 authmethods_get(void)
1962 {
1963         Authmethod *method = NULL;
1964         Buffer b;
1965         char *list;
1966
1967         buffer_init(&b);
1968         for (method = authmethods; method->name != NULL; method++) {
1969                 if (authmethod_is_enabled(method)) {
1970                         if (buffer_len(&b) > 0)
1971                                 buffer_append(&b, ",", 1);
1972                         buffer_append(&b, method->name, strlen(method->name));
1973                 }
1974         }
1975         buffer_append(&b, "\0", 1);
1976         list = xstrdup(buffer_ptr(&b));
1977         buffer_free(&b);
1978         return list;
1979 }
1980