crypto/openssh/sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.186 2010/11/29 23:45:51 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)
  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 "readconf.h"
  65 #include "misc.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 "schnorr.h"
  74 #include "jpake.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 Kex *xxx_kex = NULL;
  96
  97 static int
  98 verify_host_key_callback(Key *hostkey)
  99 {
 100         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
 101                 fatal("Host key verification failed.");
 102         return 0;
 103 }
 104
 105 static char *
 106 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
 107 {
 108         char *oavail, *avail, *first, *last, *alg, *hostname, *ret;
 109         size_t maxlen;
 110         struct hostkeys *hostkeys;
 111         int ktype;
 112
 113         /* Find all hostkeys for this hostname */
 114         get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
 115         hostkeys = init_hostkeys();
 116         load_hostkeys(hostkeys, hostname, options.user_hostfile2);
 117         load_hostkeys(hostkeys, hostname, options.system_hostfile2);
 118         load_hostkeys(hostkeys, hostname, options.user_hostfile);
 119         load_hostkeys(hostkeys, hostname, options.system_hostfile);
 120
 121         oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG);
 122         maxlen = strlen(avail) + 1;
 123         first = xmalloc(maxlen);
 124         last = xmalloc(maxlen);
 125         *first = *last = '\0';
 126
 127 #define ALG_APPEND(to, from) \
 128         do { \
 129                 if (*to != '\0') \
 130                         strlcat(to, ",", maxlen); \
 131                 strlcat(to, from, maxlen); \
 132         } while (0)
 133
 134         while ((alg = strsep(&avail, ",")) && *alg != '\0') {
 135                 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC)
 136                         fatal("%s: unknown alg %s", __func__, alg);
 137                 if (lookup_key_in_hostkeys_by_type(hostkeys,
 138                     key_type_plain(ktype), NULL))
 139                         ALG_APPEND(first, alg);
 140                 else
 141                         ALG_APPEND(last, alg);
 142         }
 143 #undef ALG_APPEND
 144         xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last);
 145         if (*first != '\0')
 146                 debug3("%s: prefer hostkeyalgs: %s", __func__, first);
 147
 148         xfree(first);
 149         xfree(last);
 150         xfree(hostname);
 151         xfree(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         Kex *kex;
 161
 162         xxx_host = host;
 163         xxx_hostaddr = hostaddr;
 164
 165         if (options.ciphers == (char *)-1) {
 166                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 167                 options.ciphers = NULL;
 168         }
 169         if (options.ciphers != NULL) {
 170                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 171                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 172         }
 173         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 174             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 175         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 176             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 177         if (options.compression) {
 178                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 179                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 180         } else {
 181                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 182                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 183         }
 184         if (options.macs != NULL) {
 185                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 186                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 187         }
 188         if (options.hostkeyalgorithms != NULL)
 189                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 190                     options.hostkeyalgorithms;
 191         else {
 192                 /* Prefer algorithms that we already have keys for */
 193                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 194                     order_hostkeyalgs(host, hostaddr, port);
 195         }
 196         if (options.kex_algorithms != NULL)
 197                 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
 198
 199         if (options.rekey_limit)
 200                 packet_set_rekey_limit((u_int32_t)options.rekey_limit);
 201
 202         /* start key exchange */
 203         kex = kex_setup(myproposal);
 204         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 205         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 206         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 207         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 208         kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
 209         kex->client_version_string=client_version_string;
 210         kex->server_version_string=server_version_string;
 211         kex->verify_host_key=&verify_host_key_callback;
 212
 213         xxx_kex = kex;
 214
 215         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 216
 217         if (options.use_roaming && !kex->roaming) {
 218                 debug("Roaming not allowed by server");
 219                 options.use_roaming = 0;
 220         }
 221
 222         session_id2 = kex->session_id;
 223         session_id2_len = kex->session_id_len;
 224
 225 #ifdef DEBUG_KEXDH
 226         /* send 1st encrypted/maced/compressed message */
 227         packet_start(SSH2_MSG_IGNORE);
 228         packet_put_cstring("markus");
 229         packet_send();
 230         packet_write_wait();
 231 #endif
 232 }
 233
 234 /*
 235  * Authenticate user
 236  */
 237
 238 typedef struct Authctxt Authctxt;
 239 typedef struct Authmethod Authmethod;
 240 typedef struct identity Identity;
 241 typedef struct idlist Idlist;
 242
 243 struct identity {
 244         TAILQ_ENTRY(identity) next;
 245         AuthenticationConnection *ac;   /* set if agent supports key */
 246         Key     *key;                   /* public/private key */
 247         char    *filename;              /* comment for agent-only keys */
 248         int     tried;
 249         int     isprivate;              /* key points to the private key */
 250 };
 251 TAILQ_HEAD(idlist, identity);
 252
 253 struct Authctxt {
 254         const char *server_user;
 255         const char *local_user;
 256         const char *host;
 257         const char *service;
 258         Authmethod *method;
 259         sig_atomic_t success;
 260         char *authlist;
 261         /* pubkey */
 262         Idlist keys;
 263         AuthenticationConnection *agent;
 264         /* hostbased */
 265         Sensitive *sensitive;
 266         /* kbd-interactive */
 267         int info_req_seen;
 268         /* generic */
 269         void *methoddata;
 270 };
 271 struct Authmethod {
 272         char    *name;          /* string to compare against server's list */
 273         int     (*userauth)(Authctxt *authctxt);
 274         void    (*cleanup)(Authctxt *authctxt);
 275         int     *enabled;       /* flag in option struct that enables method */
 276         int     *batch_flag;    /* flag in option struct that disables method */
 277 };
 278
 279 void    input_userauth_success(int, u_int32_t, void *);
 280 void    input_userauth_success_unexpected(int, u_int32_t, void *);
 281 void    input_userauth_failure(int, u_int32_t, void *);
 282 void    input_userauth_banner(int, u_int32_t, void *);
 283 void    input_userauth_error(int, u_int32_t, void *);
 284 void    input_userauth_info_req(int, u_int32_t, void *);
 285 void    input_userauth_pk_ok(int, u_int32_t, void *);
 286 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 287 void    input_userauth_jpake_server_step1(int, u_int32_t, void *);
 288 void    input_userauth_jpake_server_step2(int, u_int32_t, void *);
 289 void    input_userauth_jpake_server_confirm(int, u_int32_t, void *);
 290
 291 int     userauth_none(Authctxt *);
 292 int     userauth_pubkey(Authctxt *);
 293 int     userauth_passwd(Authctxt *);
 294 int     userauth_kbdint(Authctxt *);
 295 int     userauth_hostbased(Authctxt *);
 296 int     userauth_jpake(Authctxt *);
 297
 298 void    userauth_jpake_cleanup(Authctxt *);
 299
 300 #ifdef GSSAPI
 301 int     userauth_gssapi(Authctxt *authctxt);
 302 void    input_gssapi_response(int type, u_int32_t, void *);
 303 void    input_gssapi_token(int type, u_int32_t, void *);
 304 void    input_gssapi_hash(int type, u_int32_t, void *);
 305 void    input_gssapi_error(int, u_int32_t, void *);
 306 void    input_gssapi_errtok(int, u_int32_t, void *);
 307 #endif
 308
 309 void    userauth(Authctxt *, char *);
 310
 311 static int sign_and_send_pubkey(Authctxt *, Identity *);
 312 static void pubkey_prepare(Authctxt *);
 313 static void pubkey_cleanup(Authctxt *);
 314 static Key *load_identity_file(char *);
 315
 316 static Authmethod *authmethod_get(char *authlist);
 317 static Authmethod *authmethod_lookup(const char *name);
 318 static char *authmethods_get(void);
 319
 320 Authmethod authmethods[] = {
 321 #ifdef GSSAPI
 322         {"gssapi-with-mic",
 323                 userauth_gssapi,
 324                 NULL,
 325                 &options.gss_authentication,
 326                 NULL},
 327 #endif
 328         {"hostbased",
 329                 userauth_hostbased,
 330                 NULL,
 331                 &options.hostbased_authentication,
 332                 NULL},
 333         {"publickey",
 334                 userauth_pubkey,
 335                 NULL,
 336                 &options.pubkey_authentication,
 337                 NULL},
 338 #ifdef JPAKE
 339         {"jpake-01@openssh.com",
 340                 userauth_jpake,
 341                 userauth_jpake_cleanup,
 342                 &options.zero_knowledge_password_authentication,
 343                 &options.batch_mode},
 344 #endif
 345         {"keyboard-interactive",
 346                 userauth_kbdint,
 347                 NULL,
 348                 &options.kbd_interactive_authentication,
 349                 &options.batch_mode},
 350         {"password",
 351                 userauth_passwd,
 352                 NULL,
 353                 &options.password_authentication,
 354                 &options.batch_mode},
 355         {"none",
 356                 userauth_none,
 357                 NULL,
 358                 NULL,
 359                 NULL},
 360         {NULL, NULL, NULL, NULL, NULL}
 361 };
 362
 363 void
 364 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 365     Sensitive *sensitive)
 366 {
 367         Authctxt authctxt;
 368         int type;
 369
 370         if (options.challenge_response_authentication)
 371                 options.kbd_interactive_authentication = 1;
 372
 373         packet_start(SSH2_MSG_SERVICE_REQUEST);
 374         packet_put_cstring("ssh-userauth");
 375         packet_send();
 376         debug("SSH2_MSG_SERVICE_REQUEST sent");
 377         packet_write_wait();
 378         type = packet_read();
 379         if (type != SSH2_MSG_SERVICE_ACCEPT)
 380                 fatal("Server denied authentication request: %d", type);
 381         if (packet_remaining() > 0) {
 382                 char *reply = packet_get_string(NULL);
 383                 debug2("service_accept: %s", reply);
 384                 xfree(reply);
 385         } else {
 386                 debug2("buggy server: service_accept w/o service");
 387         }
 388         packet_check_eom();
 389         debug("SSH2_MSG_SERVICE_ACCEPT received");
 390
 391         if (options.preferred_authentications == NULL)
 392                 options.preferred_authentications = authmethods_get();
 393
 394         /* setup authentication context */
 395         memset(&authctxt, 0, sizeof(authctxt));
 396         pubkey_prepare(&authctxt);
 397         authctxt.server_user = server_user;
 398         authctxt.local_user = local_user;
 399         authctxt.host = host;
 400         authctxt.service = "ssh-connection";            /* service name */
 401         authctxt.success = 0;
 402         authctxt.method = authmethod_lookup("none");
 403         authctxt.authlist = NULL;
 404         authctxt.methoddata = NULL;
 405         authctxt.sensitive = sensitive;
 406         authctxt.info_req_seen = 0;
 407         if (authctxt.method == NULL)
 408                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 409
 410         /* initial userauth request */
 411         userauth_none(&authctxt);
 412
 413         dispatch_init(&input_userauth_error);
 414         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 415         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 416         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 417         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 418
 419         pubkey_cleanup(&authctxt);
 420         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 421
 422         debug("Authentication succeeded (%s).", authctxt.method->name);
 423 }
 424
 425 void
 426 userauth(Authctxt *authctxt, char *authlist)
 427 {
 428         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 429                 authctxt->method->cleanup(authctxt);
 430
 431         if (authctxt->methoddata) {
 432                 xfree(authctxt->methoddata);
 433                 authctxt->methoddata = NULL;
 434         }
 435         if (authlist == NULL) {
 436                 authlist = authctxt->authlist;
 437         } else {
 438                 if (authctxt->authlist)
 439                         xfree(authctxt->authlist);
 440                 authctxt->authlist = authlist;
 441         }
 442         for (;;) {
 443                 Authmethod *method = authmethod_get(authlist);
 444                 if (method == NULL)
 445                         fatal("Permission denied (%s).", authlist);
 446                 authctxt->method = method;
 447
 448                 /* reset the per method handler */
 449                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 450                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 451
 452                 /* and try new method */
 453                 if (method->userauth(authctxt) != 0) {
 454                         debug2("we sent a %s packet, wait for reply", method->name);
 455                         break;
 456                 } else {
 457                         debug2("we did not send a packet, disable method");
 458                         method->enabled = NULL;
 459                 }
 460         }
 461 }
 462
 463 /* ARGSUSED */
 464 void
 465 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 466 {
 467         fatal("input_userauth_error: bad message during authentication: "
 468             "type %d", type);
 469 }
 470
 471 /* ARGSUSED */
 472 void
 473 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 474 {
 475         char *msg, *raw, *lang;
 476         u_int len;
 477
 478         debug3("input_userauth_banner");
 479         raw = packet_get_string(&len);
 480         lang = packet_get_string(NULL);
 481         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
 482                 if (len > 65536)
 483                         len = 65536;
 484                 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
 485                 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH);
 486                 fprintf(stderr, "%s", msg);
 487                 xfree(msg);
 488         }
 489         xfree(raw);
 490         xfree(lang);
 491 }
 492
 493 /* ARGSUSED */
 494 void
 495 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 496 {
 497         Authctxt *authctxt = ctxt;
 498
 499         if (authctxt == NULL)
 500                 fatal("input_userauth_success: no authentication context");
 501         if (authctxt->authlist) {
 502                 xfree(authctxt->authlist);
 503                 authctxt->authlist = NULL;
 504         }
 505         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 506                 authctxt->method->cleanup(authctxt);
 507         if (authctxt->methoddata) {
 508                 xfree(authctxt->methoddata);
 509                 authctxt->methoddata = NULL;
 510         }
 511         authctxt->success = 1;                  /* break out */
 512 }
 513
 514 void
 515 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
 516 {
 517         Authctxt *authctxt = ctxt;
 518
 519         if (authctxt == NULL)
 520                 fatal("%s: no authentication context", __func__);
 521
 522         fatal("Unexpected authentication success during %s.",
 523             authctxt->method->name);
 524 }
 525
 526 /* ARGSUSED */
 527 void
 528 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 529 {
 530         Authctxt *authctxt = ctxt;
 531         char *authlist = NULL;
 532         int partial;
 533
 534         if (authctxt == NULL)
 535                 fatal("input_userauth_failure: no authentication context");
 536
 537         authlist = packet_get_string(NULL);
 538         partial = packet_get_char();
 539         packet_check_eom();
 540
 541         if (partial != 0)
 542                 logit("Authenticated with partial success.");
 543         debug("Authentications that can continue: %s", authlist);
 544
 545         userauth(authctxt, authlist);
 546 }
 547
 548 /* ARGSUSED */
 549 void
 550 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 551 {
 552         Authctxt *authctxt = ctxt;
 553         Key *key = NULL;
 554         Identity *id = NULL;
 555         Buffer b;
 556         int pktype, sent = 0;
 557         u_int alen, blen;
 558         char *pkalg, *fp;
 559         u_char *pkblob;
 560
 561         if (authctxt == NULL)
 562                 fatal("input_userauth_pk_ok: no authentication context");
 563         if (datafellows & SSH_BUG_PKOK) {
 564                 /* this is similar to SSH_BUG_PKAUTH */
 565                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 566                 pkblob = packet_get_string(&blen);
 567                 buffer_init(&b);
 568                 buffer_append(&b, pkblob, blen);
 569                 pkalg = buffer_get_string(&b, &alen);
 570                 buffer_free(&b);
 571         } else {
 572                 pkalg = packet_get_string(&alen);
 573                 pkblob = packet_get_string(&blen);
 574         }
 575         packet_check_eom();
 576
 577         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 578
 579         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 580                 debug("unknown pkalg %s", pkalg);
 581                 goto done;
 582         }
 583         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 584                 debug("no key from blob. pkalg %s", pkalg);
 585                 goto done;
 586         }
 587         if (key->type != pktype) {
 588                 error("input_userauth_pk_ok: type mismatch "
 589                     "for decoded key (received %d, expected %d)",
 590                     key->type, pktype);
 591                 goto done;
 592         }
 593         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 594         debug2("input_userauth_pk_ok: fp %s", fp);
 595         xfree(fp);
 596
 597         /*
 598          * search keys in the reverse order, because last candidate has been
 599          * moved to the end of the queue.  this also avoids confusion by
 600          * duplicate keys
 601          */
 602         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 603                 if (key_equal(key, id->key)) {
 604                         sent = sign_and_send_pubkey(authctxt, id);
 605                         break;
 606                 }
 607         }
 608 done:
 609         if (key != NULL)
 610                 key_free(key);
 611         xfree(pkalg);
 612         xfree(pkblob);
 613
 614         /* try another method if we did not send a packet */
 615         if (sent == 0)
 616                 userauth(authctxt, NULL);
 617 }
 618
 619 #ifdef GSSAPI
 620 int
 621 userauth_gssapi(Authctxt *authctxt)
 622 {
 623         Gssctxt *gssctxt = NULL;
 624         static gss_OID_set gss_supported = NULL;
 625         static u_int mech = 0;
 626         OM_uint32 min;
 627         int ok = 0;
 628
 629         /* Try one GSSAPI method at a time, rather than sending them all at
 630          * once. */
 631
 632         if (gss_supported == NULL)
 633                 gss_indicate_mechs(&min, &gss_supported);
 634
 635         /* Check to see if the mechanism is usable before we offer it */
 636         while (mech < gss_supported->count && !ok) {
 637                 /* My DER encoding requires length<128 */
 638                 if (gss_supported->elements[mech].length < 128 &&
 639                     ssh_gssapi_check_mechanism(&gssctxt,
 640                     &gss_supported->elements[mech], authctxt->host)) {
 641                         ok = 1; /* Mechanism works */
 642                 } else {
 643                         mech++;
 644                 }
 645         }
 646
 647         if (!ok)
 648                 return 0;
 649
 650         authctxt->methoddata=(void *)gssctxt;
 651
 652         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 653         packet_put_cstring(authctxt->server_user);
 654         packet_put_cstring(authctxt->service);
 655         packet_put_cstring(authctxt->method->name);
 656
 657         packet_put_int(1);
 658
 659         packet_put_int((gss_supported->elements[mech].length) + 2);
 660         packet_put_char(SSH_GSS_OIDTYPE);
 661         packet_put_char(gss_supported->elements[mech].length);
 662         packet_put_raw(gss_supported->elements[mech].elements,
 663             gss_supported->elements[mech].length);
 664
 665         packet_send();
 666
 667         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 668         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 669         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 670         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 671
 672         mech++; /* Move along to next candidate */
 673
 674         return 1;
 675 }
 676
 677 static OM_uint32
 678 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 679 {
 680         Authctxt *authctxt = ctxt;
 681         Gssctxt *gssctxt = authctxt->methoddata;
 682         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 683         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 684         gss_buffer_desc gssbuf;
 685         OM_uint32 status, ms, flags;
 686         Buffer b;
 687
 688         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 689             recv_tok, &send_tok, &flags);
 690
 691         if (send_tok.length > 0) {
 692                 if (GSS_ERROR(status))
 693                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 694                 else
 695                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 696
 697                 packet_put_string(send_tok.value, send_tok.length);
 698                 packet_send();
 699                 gss_release_buffer(&ms, &send_tok);
 700         }
 701
 702         if (status == GSS_S_COMPLETE) {
 703                 /* send either complete or MIC, depending on mechanism */
 704                 if (!(flags & GSS_C_INTEG_FLAG)) {
 705                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 706                         packet_send();
 707                 } else {
 708                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 709                             authctxt->service, "gssapi-with-mic");
 710
 711                         gssbuf.value = buffer_ptr(&b);
 712                         gssbuf.length = buffer_len(&b);
 713
 714                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 715
 716                         if (!GSS_ERROR(status)) {
 717                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 718                                 packet_put_string(mic.value, mic.length);
 719
 720                                 packet_send();
 721                         }
 722
 723                         buffer_free(&b);
 724                         gss_release_buffer(&ms, &mic);
 725                 }
 726         }
 727
 728         return status;
 729 }
 730
 731 /* ARGSUSED */
 732 void
 733 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 734 {
 735         Authctxt *authctxt = ctxt;
 736         Gssctxt *gssctxt;
 737         int oidlen;
 738         char *oidv;
 739
 740         if (authctxt == NULL)
 741                 fatal("input_gssapi_response: no authentication context");
 742         gssctxt = authctxt->methoddata;
 743
 744         /* Setup our OID */
 745         oidv = packet_get_string(&oidlen);
 746
 747         if (oidlen <= 2 ||
 748             oidv[0] != SSH_GSS_OIDTYPE ||
 749             oidv[1] != oidlen - 2) {
 750                 xfree(oidv);
 751                 debug("Badly encoded mechanism OID received");
 752                 userauth(authctxt, NULL);
 753                 return;
 754         }
 755
 756         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 757                 fatal("Server returned different OID than expected");
 758
 759         packet_check_eom();
 760
 761         xfree(oidv);
 762
 763         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 764                 /* Start again with next method on list */
 765                 debug("Trying to start again");
 766                 userauth(authctxt, NULL);
 767                 return;
 768         }
 769 }
 770
 771 /* ARGSUSED */
 772 void
 773 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 774 {
 775         Authctxt *authctxt = ctxt;
 776         gss_buffer_desc recv_tok;
 777         OM_uint32 status;
 778         u_int slen;
 779
 780         if (authctxt == NULL)
 781                 fatal("input_gssapi_response: no authentication context");
 782
 783         recv_tok.value = packet_get_string(&slen);
 784         recv_tok.length = slen; /* safe typecast */
 785
 786         packet_check_eom();
 787
 788         status = process_gssapi_token(ctxt, &recv_tok);
 789
 790         xfree(recv_tok.value);
 791
 792         if (GSS_ERROR(status)) {
 793                 /* Start again with the next method in the list */
 794                 userauth(authctxt, NULL);
 795                 return;
 796         }
 797 }
 798
 799 /* ARGSUSED */
 800 void
 801 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 802 {
 803         Authctxt *authctxt = ctxt;
 804         Gssctxt *gssctxt;
 805         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 806         gss_buffer_desc recv_tok;
 807         OM_uint32 status, ms;
 808         u_int len;
 809
 810         if (authctxt == NULL)
 811                 fatal("input_gssapi_response: no authentication context");
 812         gssctxt = authctxt->methoddata;
 813
 814         recv_tok.value = packet_get_string(&len);
 815         recv_tok.length = len;
 816
 817         packet_check_eom();
 818
 819         /* Stick it into GSSAPI and see what it says */
 820         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 821             &recv_tok, &send_tok, NULL);
 822
 823         xfree(recv_tok.value);
 824         gss_release_buffer(&ms, &send_tok);
 825
 826         /* Server will be returning a failed packet after this one */
 827 }
 828
 829 /* ARGSUSED */
 830 void
 831 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 832 {
 833         OM_uint32 maj, min;
 834         char *msg;
 835         char *lang;
 836
 837         maj=packet_get_int();
 838         min=packet_get_int();
 839         msg=packet_get_string(NULL);
 840         lang=packet_get_string(NULL);
 841
 842         packet_check_eom();
 843
 844         debug("Server GSSAPI Error:\n%s", msg);
 845         xfree(msg);
 846         xfree(lang);
 847 }
 848 #endif /* GSSAPI */
 849
 850 int
 851 userauth_none(Authctxt *authctxt)
 852 {
 853         /* initial userauth request */
 854         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 855         packet_put_cstring(authctxt->server_user);
 856         packet_put_cstring(authctxt->service);
 857         packet_put_cstring(authctxt->method->name);
 858         packet_send();
 859         return 1;
 860 }
 861
 862 int
 863 userauth_passwd(Authctxt *authctxt)
 864 {
 865         static int attempt = 0;
 866         char prompt[150];
 867         char *password;
 868         const char *host = options.host_key_alias ?  options.host_key_alias :
 869             authctxt->host;
 870
 871         if (attempt++ >= options.number_of_password_prompts)
 872                 return 0;
 873
 874         if (attempt != 1)
 875                 error("Permission denied, please try again.");
 876
 877         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 878             authctxt->server_user, host);
 879         password = read_passphrase(prompt, 0);
 880         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 881         packet_put_cstring(authctxt->server_user);
 882         packet_put_cstring(authctxt->service);
 883         packet_put_cstring(authctxt->method->name);
 884         packet_put_char(0);
 885         packet_put_cstring(password);
 886         memset(password, 0, strlen(password));
 887         xfree(password);
 888         packet_add_padding(64);
 889         packet_send();
 890
 891         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 892             &input_userauth_passwd_changereq);
 893
 894         return 1;
 895 }
 896
 897 /*
 898  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 899  */
 900 /* ARGSUSED */
 901 void
 902 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 903 {
 904         Authctxt *authctxt = ctxt;
 905         char *info, *lang, *password = NULL, *retype = NULL;
 906         char prompt[150];
 907         const char *host = options.host_key_alias ? options.host_key_alias :
 908             authctxt->host;
 909
 910         debug2("input_userauth_passwd_changereq");
 911
 912         if (authctxt == NULL)
 913                 fatal("input_userauth_passwd_changereq: "
 914                     "no authentication context");
 915
 916         info = packet_get_string(NULL);
 917         lang = packet_get_string(NULL);
 918         if (strlen(info) > 0)
 919                 logit("%s", info);
 920         xfree(info);
 921         xfree(lang);
 922         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 923         packet_put_cstring(authctxt->server_user);
 924         packet_put_cstring(authctxt->service);
 925         packet_put_cstring(authctxt->method->name);
 926         packet_put_char(1);                     /* additional info */
 927         snprintf(prompt, sizeof(prompt),
 928             "Enter %.30s@%.128s's old password: ",
 929             authctxt->server_user, host);
 930         password = read_passphrase(prompt, 0);
 931         packet_put_cstring(password);
 932         memset(password, 0, strlen(password));
 933         xfree(password);
 934         password = NULL;
 935         while (password == NULL) {
 936                 snprintf(prompt, sizeof(prompt),
 937                     "Enter %.30s@%.128s's new password: ",
 938                     authctxt->server_user, host);
 939                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 940                 if (password == NULL) {
 941                         /* bail out */
 942                         return;
 943                 }
 944                 snprintf(prompt, sizeof(prompt),
 945                     "Retype %.30s@%.128s's new password: ",
 946                     authctxt->server_user, host);
 947                 retype = read_passphrase(prompt, 0);
 948                 if (strcmp(password, retype) != 0) {
 949                         memset(password, 0, strlen(password));
 950                         xfree(password);
 951                         logit("Mismatch; try again, EOF to quit.");
 952                         password = NULL;
 953                 }
 954                 memset(retype, 0, strlen(retype));
 955                 xfree(retype);
 956         }
 957         packet_put_cstring(password);
 958         memset(password, 0, strlen(password));
 959         xfree(password);
 960         packet_add_padding(64);
 961         packet_send();
 962
 963         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 964             &input_userauth_passwd_changereq);
 965 }
 966
 967 #ifdef JPAKE
 968 static char *
 969 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt)
 970 {
 971         /* OpenBSD crypt(3) handles all of these */
 972         if (strcmp(crypt_scheme, "crypt") == 0 ||
 973             strcmp(crypt_scheme, "bcrypt") == 0 ||
 974             strcmp(crypt_scheme, "md5crypt") == 0 ||
 975             strcmp(crypt_scheme, "crypt-extended") == 0)
 976                 return xstrdup(crypt(password, salt));
 977         error("%s: unsupported password encryption scheme \"%.100s\"",
 978             __func__, crypt_scheme);
 979         return NULL;
 980 }
 981
 982 static BIGNUM *
 983 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme,
 984     const char *salt)
 985 {
 986         char prompt[256], *password, *crypted;
 987         u_char *secret;
 988         u_int secret_len;
 989         BIGNUM *ret;
 990
 991         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ",
 992             authctxt->server_user, authctxt->host);
 993         password = read_passphrase(prompt, 0);
 994
 995         if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) {
 996                 logit("Disabling %s authentication", authctxt->method->name);
 997                 authctxt->method->enabled = NULL;
 998                 /* Continue with an empty password to fail gracefully */
 999                 crypted = xstrdup("");
1000         }
1001
1002 #ifdef JPAKE_DEBUG
1003         debug3("%s: salt = %s", __func__, salt);
1004         debug3("%s: scheme = %s", __func__, crypt_scheme);
1005         debug3("%s: crypted = %s", __func__, crypted);
1006 #endif
1007
1008         if (hash_buffer(crypted, strlen(crypted), EVP_sha256(),
1009             &secret, &secret_len) != 0)
1010                 fatal("%s: hash_buffer", __func__);
1011
1012         bzero(password, strlen(password));
1013         bzero(crypted, strlen(crypted));
1014         xfree(password);
1015         xfree(crypted);
1016
1017         if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL)
1018                 fatal("%s: BN_bin2bn (secret)", __func__);
1019         bzero(secret, secret_len);
1020         xfree(secret);
1021
1022         return ret;
1023 }
1024
1025 /* ARGSUSED */
1026 void
1027 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt)
1028 {
1029         Authctxt *authctxt = ctxt;
1030         struct jpake_ctx *pctx = authctxt->methoddata;
1031         u_char *x3_proof, *x4_proof, *x2_s_proof;
1032         u_int x3_proof_len, x4_proof_len, x2_s_proof_len;
1033         char *crypt_scheme, *salt;
1034
1035         /* Disable this message */
1036         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL);
1037
1038         if ((pctx->g_x3 = BN_new()) == NULL ||
1039             (pctx->g_x4 = BN_new()) == NULL)
1040                 fatal("%s: BN_new", __func__);
1041
1042         /* Fetch step 1 values */
1043         crypt_scheme = packet_get_string(NULL);
1044         salt = packet_get_string(NULL);
1045         pctx->server_id = packet_get_string(&pctx->server_id_len);
1046         packet_get_bignum2(pctx->g_x3);
1047         packet_get_bignum2(pctx->g_x4);
1048         x3_proof = packet_get_string(&x3_proof_len);
1049         x4_proof = packet_get_string(&x4_proof_len);
1050         packet_check_eom();
1051
1052         JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__));
1053
1054         /* Obtain password and derive secret */
1055         pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt);
1056         bzero(crypt_scheme, strlen(crypt_scheme));
1057         bzero(salt, strlen(salt));
1058         xfree(crypt_scheme);
1059         xfree(salt);
1060         JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__));
1061
1062         /* Calculate step 2 values */
1063         jpake_step2(pctx->grp, pctx->s, pctx->g_x1,
1064             pctx->g_x3, pctx->g_x4, pctx->x2,
1065             pctx->server_id, pctx->server_id_len,
1066             pctx->client_id, pctx->client_id_len,
1067             x3_proof, x3_proof_len,
1068             x4_proof, x4_proof_len,
1069             &pctx->a,
1070             &x2_s_proof, &x2_s_proof_len);
1071
1072         bzero(x3_proof, x3_proof_len);
1073         bzero(x4_proof, x4_proof_len);
1074         xfree(x3_proof);
1075         xfree(x4_proof);
1076
1077         JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__));
1078
1079         /* Send values for step 2 */
1080         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2);
1081         packet_put_bignum2(pctx->a);
1082         packet_put_string(x2_s_proof, x2_s_proof_len);
1083         packet_send();
1084
1085         bzero(x2_s_proof, x2_s_proof_len);
1086         xfree(x2_s_proof);
1087
1088         /* Expect step 2 packet from peer */
1089         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2,
1090             input_userauth_jpake_server_step2);
1091 }
1092
1093 /* ARGSUSED */
1094 void
1095 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt)
1096 {
1097         Authctxt *authctxt = ctxt;
1098         struct jpake_ctx *pctx = authctxt->methoddata;
1099         u_char *x4_s_proof;
1100         u_int x4_s_proof_len;
1101
1102         /* Disable this message */
1103         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL);
1104
1105         if ((pctx->b = BN_new()) == NULL)
1106                 fatal("%s: BN_new", __func__);
1107
1108         /* Fetch step 2 values */
1109         packet_get_bignum2(pctx->b);
1110         x4_s_proof = packet_get_string(&x4_s_proof_len);
1111         packet_check_eom();
1112
1113         JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__));
1114
1115         /* Derive shared key and calculate confirmation hash */
1116         jpake_key_confirm(pctx->grp, pctx->s, pctx->b,
1117             pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4,
1118             pctx->client_id, pctx->client_id_len,
1119             pctx->server_id, pctx->server_id_len,
1120             session_id2, session_id2_len,
1121             x4_s_proof, x4_s_proof_len,
1122             &pctx->k,
1123             &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len);
1124
1125         bzero(x4_s_proof, x4_s_proof_len);
1126         xfree(x4_s_proof);
1127
1128         JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__));
1129
1130         /* Send key confirmation proof */
1131         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM);
1132         packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len);
1133         packet_send();
1134
1135         /* Expect confirmation from peer */
1136         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM,
1137             input_userauth_jpake_server_confirm);
1138 }
1139
1140 /* ARGSUSED */
1141 void
1142 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt)
1143 {
1144         Authctxt *authctxt = ctxt;
1145         struct jpake_ctx *pctx = authctxt->methoddata;
1146
1147         /* Disable this message */
1148         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL);
1149
1150         pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len);
1151         packet_check_eom();
1152
1153         JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__));
1154
1155         /* Verify expected confirmation hash */
1156         if (jpake_check_confirm(pctx->k,
1157             pctx->server_id, pctx->server_id_len,
1158             session_id2, session_id2_len,
1159             pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1)
1160                 debug("%s: %s success", __func__, authctxt->method->name);
1161         else {
1162                 debug("%s: confirmation mismatch", __func__);
1163                 /* XXX stash this so if auth succeeds then we can warn/kill */
1164         }
1165
1166         userauth_jpake_cleanup(authctxt);
1167 }
1168 #endif /* JPAKE */
1169
1170 static int
1171 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
1172     u_char *data, u_int datalen)
1173 {
1174         Key *prv;
1175         int ret;
1176
1177         /* the agent supports this key */
1178         if (id->ac)
1179                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1180                     data, datalen));
1181         /*
1182          * we have already loaded the private key or
1183          * the private key is stored in external hardware
1184          */
1185         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1186                 return (key_sign(id->key, sigp, lenp, data, datalen));
1187         /* load the private key from the file */
1188         if ((prv = load_identity_file(id->filename)) == NULL)
1189                 return (-1);
1190         ret = key_sign(prv, sigp, lenp, data, datalen);
1191         key_free(prv);
1192         return (ret);
1193 }
1194
1195 static int
1196 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1197 {
1198         Buffer b;
1199         u_char *blob, *signature;
1200         u_int bloblen, slen;
1201         u_int skip = 0;
1202         int ret = -1;
1203         int have_sig = 1;
1204         char *fp;
1205
1206         fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
1207         debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp);
1208         xfree(fp);
1209
1210         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1211                 /* we cannot handle this key */
1212                 debug3("sign_and_send_pubkey: cannot handle key");
1213                 return 0;
1214         }
1215         /* data to be signed */
1216         buffer_init(&b);
1217         if (datafellows & SSH_OLD_SESSIONID) {
1218                 buffer_append(&b, session_id2, session_id2_len);
1219                 skip = session_id2_len;
1220         } else {
1221                 buffer_put_string(&b, session_id2, session_id2_len);
1222                 skip = buffer_len(&b);
1223         }
1224         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1225         buffer_put_cstring(&b, authctxt->server_user);
1226         buffer_put_cstring(&b,
1227             datafellows & SSH_BUG_PKSERVICE ?
1228             "ssh-userauth" :
1229             authctxt->service);
1230         if (datafellows & SSH_BUG_PKAUTH) {
1231                 buffer_put_char(&b, have_sig);
1232         } else {
1233                 buffer_put_cstring(&b, authctxt->method->name);
1234                 buffer_put_char(&b, have_sig);
1235                 buffer_put_cstring(&b, key_ssh_name(id->key));
1236         }
1237         buffer_put_string(&b, blob, bloblen);
1238
1239         /* generate signature */
1240         ret = identity_sign(id, &signature, &slen,
1241             buffer_ptr(&b), buffer_len(&b));
1242         if (ret == -1) {
1243                 xfree(blob);
1244                 buffer_free(&b);
1245                 return 0;
1246         }
1247 #ifdef DEBUG_PK
1248         buffer_dump(&b);
1249 #endif
1250         if (datafellows & SSH_BUG_PKSERVICE) {
1251                 buffer_clear(&b);
1252                 buffer_append(&b, session_id2, session_id2_len);
1253                 skip = session_id2_len;
1254                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1255                 buffer_put_cstring(&b, authctxt->server_user);
1256                 buffer_put_cstring(&b, authctxt->service);
1257                 buffer_put_cstring(&b, authctxt->method->name);
1258                 buffer_put_char(&b, have_sig);
1259                 if (!(datafellows & SSH_BUG_PKAUTH))
1260                         buffer_put_cstring(&b, key_ssh_name(id->key));
1261                 buffer_put_string(&b, blob, bloblen);
1262         }
1263         xfree(blob);
1264
1265         /* append signature */
1266         buffer_put_string(&b, signature, slen);
1267         xfree(signature);
1268
1269         /* skip session id and packet type */
1270         if (buffer_len(&b) < skip + 1)
1271                 fatal("userauth_pubkey: internal error");
1272         buffer_consume(&b, skip + 1);
1273
1274         /* put remaining data from buffer into packet */
1275         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1276         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1277         buffer_free(&b);
1278         packet_send();
1279
1280         return 1;
1281 }
1282
1283 static int
1284 send_pubkey_test(Authctxt *authctxt, Identity *id)
1285 {
1286         u_char *blob;
1287         u_int bloblen, have_sig = 0;
1288
1289         debug3("send_pubkey_test");
1290
1291         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1292                 /* we cannot handle this key */
1293                 debug3("send_pubkey_test: cannot handle key");
1294                 return 0;
1295         }
1296         /* register callback for USERAUTH_PK_OK message */
1297         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1298
1299         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1300         packet_put_cstring(authctxt->server_user);
1301         packet_put_cstring(authctxt->service);
1302         packet_put_cstring(authctxt->method->name);
1303         packet_put_char(have_sig);
1304         if (!(datafellows & SSH_BUG_PKAUTH))
1305                 packet_put_cstring(key_ssh_name(id->key));
1306         packet_put_string(blob, bloblen);
1307         xfree(blob);
1308         packet_send();
1309         return 1;
1310 }
1311
1312 static Key *
1313 load_identity_file(char *filename)
1314 {
1315         Key *private;
1316         char prompt[300], *passphrase;
1317         int perm_ok = 0, quit, i;
1318         struct stat st;
1319
1320         if (stat(filename, &st) < 0) {
1321                 debug3("no such identity: %s", filename);
1322                 return NULL;
1323         }
1324         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1325         if (!perm_ok)
1326                 return NULL;
1327         if (private == NULL) {
1328                 if (options.batch_mode)
1329                         return NULL;
1330                 snprintf(prompt, sizeof prompt,
1331                     "Enter passphrase for key '%.100s': ", filename);
1332                 for (i = 0; i < options.number_of_password_prompts; i++) {
1333                         passphrase = read_passphrase(prompt, 0);
1334                         if (strcmp(passphrase, "") != 0) {
1335                                 private = key_load_private_type(KEY_UNSPEC,
1336                                     filename, passphrase, NULL, NULL);
1337                                 quit = 0;
1338                         } else {
1339                                 debug2("no passphrase given, try next key");
1340                                 quit = 1;
1341                         }
1342                         memset(passphrase, 0, strlen(passphrase));
1343                         xfree(passphrase);
1344                         if (private != NULL || quit)
1345                                 break;
1346                         debug2("bad passphrase given, try again...");
1347                 }
1348         }
1349         return private;
1350 }
1351
1352 /*
1353  * try keys in the following order:
1354  *      1. agent keys that are found in the config file
1355  *      2. other agent keys
1356  *      3. keys that are only listed in the config file
1357  */
1358 static void
1359 pubkey_prepare(Authctxt *authctxt)
1360 {
1361         Identity *id;
1362         Idlist agent, files, *preferred;
1363         Key *key;
1364         AuthenticationConnection *ac;
1365         char *comment;
1366         int i, found;
1367
1368         TAILQ_INIT(&agent);     /* keys from the agent */
1369         TAILQ_INIT(&files);     /* keys from the config file */
1370         preferred = &authctxt->keys;
1371         TAILQ_INIT(preferred);  /* preferred order of keys */
1372
1373         /* list of keys stored in the filesystem */
1374         for (i = 0; i < options.num_identity_files; i++) {
1375                 key = options.identity_keys[i];
1376                 if (key && key->type == KEY_RSA1)
1377                         continue;
1378                 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1379                         continue;
1380                 options.identity_keys[i] = NULL;
1381                 id = xcalloc(1, sizeof(*id));
1382                 id->key = key;
1383                 id->filename = xstrdup(options.identity_files[i]);
1384                 TAILQ_INSERT_TAIL(&files, id, next);
1385         }
1386         /* list of keys supported by the agent */
1387         if ((ac = ssh_get_authentication_connection())) {
1388                 for (key = ssh_get_first_identity(ac, &comment, 2);
1389                     key != NULL;
1390                     key = ssh_get_next_identity(ac, &comment, 2)) {
1391                         found = 0;
1392                         TAILQ_FOREACH(id, &files, next) {
1393                                 /* agent keys from the config file are preferred */
1394                                 if (key_equal(key, id->key)) {
1395                                         key_free(key);
1396                                         xfree(comment);
1397                                         TAILQ_REMOVE(&files, id, next);
1398                                         TAILQ_INSERT_TAIL(preferred, id, next);
1399                                         id->ac = ac;
1400                                         found = 1;
1401                                         break;
1402                                 }
1403                         }
1404                         if (!found && !options.identities_only) {
1405                                 id = xcalloc(1, sizeof(*id));
1406                                 id->key = key;
1407                                 id->filename = comment;
1408                                 id->ac = ac;
1409                                 TAILQ_INSERT_TAIL(&agent, id, next);
1410                         }
1411                 }
1412                 /* append remaining agent keys */
1413                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1414                         TAILQ_REMOVE(&agent, id, next);
1415                         TAILQ_INSERT_TAIL(preferred, id, next);
1416                 }
1417                 authctxt->agent = ac;
1418         }
1419         /* append remaining keys from the config file */
1420         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1421                 TAILQ_REMOVE(&files, id, next);
1422                 TAILQ_INSERT_TAIL(preferred, id, next);
1423         }
1424         TAILQ_FOREACH(id, preferred, next) {
1425                 debug2("key: %s (%p)", id->filename, id->key);
1426         }
1427 }
1428
1429 static void
1430 pubkey_cleanup(Authctxt *authctxt)
1431 {
1432         Identity *id;
1433
1434         if (authctxt->agent != NULL)
1435                 ssh_close_authentication_connection(authctxt->agent);
1436         for (id = TAILQ_FIRST(&authctxt->keys); id;
1437             id = TAILQ_FIRST(&authctxt->keys)) {
1438                 TAILQ_REMOVE(&authctxt->keys, id, next);
1439                 if (id->key)
1440                         key_free(id->key);
1441                 if (id->filename)
1442                         xfree(id->filename);
1443                 xfree(id);
1444         }
1445 }
1446
1447 int
1448 userauth_pubkey(Authctxt *authctxt)
1449 {
1450         Identity *id;
1451         int sent = 0;
1452
1453         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1454                 if (id->tried++)
1455                         return (0);
1456                 /* move key to the end of the queue */
1457                 TAILQ_REMOVE(&authctxt->keys, id, next);
1458                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1459                 /*
1460                  * send a test message if we have the public key. for
1461                  * encrypted keys we cannot do this and have to load the
1462                  * private key instead
1463                  */
1464                 if (id->key && id->key->type != KEY_RSA1) {
1465                         debug("Offering %s public key: %s", key_type(id->key),
1466                             id->filename);
1467                         sent = send_pubkey_test(authctxt, id);
1468                 } else if (id->key == NULL) {
1469                         debug("Trying private key: %s", id->filename);
1470                         id->key = load_identity_file(id->filename);
1471                         if (id->key != NULL) {
1472                                 id->isprivate = 1;
1473                                 sent = sign_and_send_pubkey(authctxt, id);
1474                                 key_free(id->key);
1475                                 id->key = NULL;
1476                         }
1477                 }
1478                 if (sent)
1479                         return (sent);
1480         }
1481         return (0);
1482 }
1483
1484 /*
1485  * Send userauth request message specifying keyboard-interactive method.
1486  */
1487 int
1488 userauth_kbdint(Authctxt *authctxt)
1489 {
1490         static int attempt = 0;
1491
1492         if (attempt++ >= options.number_of_password_prompts)
1493                 return 0;
1494         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1495         if (attempt > 1 && !authctxt->info_req_seen) {
1496                 debug3("userauth_kbdint: disable: no info_req_seen");
1497                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1498                 return 0;
1499         }
1500
1501         debug2("userauth_kbdint");
1502         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1503         packet_put_cstring(authctxt->server_user);
1504         packet_put_cstring(authctxt->service);
1505         packet_put_cstring(authctxt->method->name);
1506         packet_put_cstring("");                                 /* lang */
1507         packet_put_cstring(options.kbd_interactive_devices ?
1508             options.kbd_interactive_devices : "");
1509         packet_send();
1510
1511         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1512         return 1;
1513 }
1514
1515 /*
1516  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1517  */
1518 void
1519 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1520 {
1521         Authctxt *authctxt = ctxt;
1522         char *name, *inst, *lang, *prompt, *response;
1523         u_int num_prompts, i;
1524         int echo = 0;
1525
1526         debug2("input_userauth_info_req");
1527
1528         if (authctxt == NULL)
1529                 fatal("input_userauth_info_req: no authentication context");
1530
1531         authctxt->info_req_seen = 1;
1532
1533         name = packet_get_string(NULL);
1534         inst = packet_get_string(NULL);
1535         lang = packet_get_string(NULL);
1536         if (strlen(name) > 0)
1537                 logit("%s", name);
1538         if (strlen(inst) > 0)
1539                 logit("%s", inst);
1540         xfree(name);
1541         xfree(inst);
1542         xfree(lang);
1543
1544         num_prompts = packet_get_int();
1545         /*
1546          * Begin to build info response packet based on prompts requested.
1547          * We commit to providing the correct number of responses, so if
1548          * further on we run into a problem that prevents this, we have to
1549          * be sure and clean this up and send a correct error response.
1550          */
1551         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1552         packet_put_int(num_prompts);
1553
1554         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1555         for (i = 0; i < num_prompts; i++) {
1556                 prompt = packet_get_string(NULL);
1557                 echo = packet_get_char();
1558
1559                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1560
1561                 packet_put_cstring(response);
1562                 memset(response, 0, strlen(response));
1563                 xfree(response);
1564                 xfree(prompt);
1565         }
1566         packet_check_eom(); /* done with parsing incoming message. */
1567
1568         packet_add_padding(64);
1569         packet_send();
1570 }
1571
1572 static int
1573 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1574     u_char *data, u_int datalen)
1575 {
1576         Buffer b;
1577         struct stat st;
1578         pid_t pid;
1579         int to[2], from[2], status, version = 2;
1580
1581         debug2("ssh_keysign called");
1582
1583         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1584                 error("ssh_keysign: not installed: %s", strerror(errno));
1585                 return -1;
1586         }
1587         if (fflush(stdout) != 0)
1588                 error("ssh_keysign: fflush: %s", strerror(errno));
1589         if (pipe(to) < 0) {
1590                 error("ssh_keysign: pipe: %s", strerror(errno));
1591                 return -1;
1592         }
1593         if (pipe(from) < 0) {
1594                 error("ssh_keysign: pipe: %s", strerror(errno));
1595                 return -1;
1596         }
1597         if ((pid = fork()) < 0) {
1598                 error("ssh_keysign: fork: %s", strerror(errno));
1599                 return -1;
1600         }
1601         if (pid == 0) {
1602                 /* keep the socket on exec */
1603                 fcntl(packet_get_connection_in(), F_SETFD, 0);
1604                 permanently_drop_suid(getuid());
1605                 close(from[0]);
1606                 if (dup2(from[1], STDOUT_FILENO) < 0)
1607                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1608                 close(to[1]);
1609                 if (dup2(to[0], STDIN_FILENO) < 0)
1610                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1611                 close(from[1]);
1612                 close(to[0]);
1613                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1614                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1615                     strerror(errno));
1616         }
1617         close(from[1]);
1618         close(to[0]);
1619
1620         buffer_init(&b);
1621         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1622         buffer_put_string(&b, data, datalen);
1623         if (ssh_msg_send(to[1], version, &b) == -1)
1624                 fatal("ssh_keysign: couldn't send request");
1625
1626         if (ssh_msg_recv(from[0], &b) < 0) {
1627                 error("ssh_keysign: no reply");
1628                 buffer_free(&b);
1629                 return -1;
1630         }
1631         close(from[0]);
1632         close(to[1]);
1633
1634         while (waitpid(pid, &status, 0) < 0)
1635                 if (errno != EINTR)
1636                         break;
1637
1638         if (buffer_get_char(&b) != version) {
1639                 error("ssh_keysign: bad version");
1640                 buffer_free(&b);
1641                 return -1;
1642         }
1643         *sigp = buffer_get_string(&b, lenp);
1644         buffer_free(&b);
1645
1646         return 0;
1647 }
1648
1649 int
1650 userauth_hostbased(Authctxt *authctxt)
1651 {
1652         Key *private = NULL;
1653         Sensitive *sensitive = authctxt->sensitive;
1654         Buffer b;
1655         u_char *signature, *blob;
1656         char *chost, *pkalg, *p;
1657         const char *service;
1658         u_int blen, slen;
1659         int ok, i, found = 0;
1660
1661         /* check for a useful key */
1662         for (i = 0; i < sensitive->nkeys; i++) {
1663                 private = sensitive->keys[i];
1664                 if (private && private->type != KEY_RSA1) {
1665                         found = 1;
1666                         /* we take and free the key */
1667                         sensitive->keys[i] = NULL;
1668                         break;
1669                 }
1670         }
1671         if (!found) {
1672                 debug("No more client hostkeys for hostbased authentication.");
1673                 return 0;
1674         }
1675         if (key_to_blob(private, &blob, &blen) == 0) {
1676                 key_free(private);
1677                 return 0;
1678         }
1679         /* figure out a name for the client host */
1680         p = get_local_name(packet_get_connection_in());
1681         if (p == NULL) {
1682                 error("userauth_hostbased: cannot get local ipaddr/name");
1683                 key_free(private);
1684                 xfree(blob);
1685                 return 0;
1686         }
1687         xasprintf(&chost, "%s.", p);
1688         debug2("userauth_hostbased: chost %s", chost);
1689         xfree(p);
1690
1691         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1692             authctxt->service;
1693         pkalg = xstrdup(key_ssh_name(private));
1694         buffer_init(&b);
1695         /* construct data */
1696         buffer_put_string(&b, session_id2, session_id2_len);
1697         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1698         buffer_put_cstring(&b, authctxt->server_user);
1699         buffer_put_cstring(&b, service);
1700         buffer_put_cstring(&b, authctxt->method->name);
1701         buffer_put_cstring(&b, pkalg);
1702         buffer_put_string(&b, blob, blen);
1703         buffer_put_cstring(&b, chost);
1704         buffer_put_cstring(&b, authctxt->local_user);
1705 #ifdef DEBUG_PK
1706         buffer_dump(&b);
1707 #endif
1708         if (sensitive->external_keysign)
1709                 ok = ssh_keysign(private, &signature, &slen,
1710                     buffer_ptr(&b), buffer_len(&b));
1711         else
1712                 ok = key_sign(private, &signature, &slen,
1713                     buffer_ptr(&b), buffer_len(&b));
1714         key_free(private);
1715         buffer_free(&b);
1716         if (ok != 0) {
1717                 error("key_sign failed");
1718                 xfree(chost);
1719                 xfree(pkalg);
1720                 xfree(blob);
1721                 return 0;
1722         }
1723         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1724         packet_put_cstring(authctxt->server_user);
1725         packet_put_cstring(authctxt->service);
1726         packet_put_cstring(authctxt->method->name);
1727         packet_put_cstring(pkalg);
1728         packet_put_string(blob, blen);
1729         packet_put_cstring(chost);
1730         packet_put_cstring(authctxt->local_user);
1731         packet_put_string(signature, slen);
1732         memset(signature, 's', slen);
1733         xfree(signature);
1734         xfree(chost);
1735         xfree(pkalg);
1736         xfree(blob);
1737
1738         packet_send();
1739         return 1;
1740 }
1741
1742 #ifdef JPAKE
1743 int
1744 userauth_jpake(Authctxt *authctxt)
1745 {
1746         struct jpake_ctx *pctx;
1747         u_char *x1_proof, *x2_proof;
1748         u_int x1_proof_len, x2_proof_len;
1749         static int attempt = 0; /* XXX share with userauth_password's? */
1750
1751         if (attempt++ >= options.number_of_password_prompts)
1752                 return 0;
1753         if (attempt != 1)
1754                 error("Permission denied, please try again.");
1755
1756         if (authctxt->methoddata != NULL)
1757                 fatal("%s: authctxt->methoddata already set (%p)",
1758                     __func__, authctxt->methoddata);
1759
1760         authctxt->methoddata = pctx = jpake_new();
1761
1762         /*
1763          * Send request immediately, to get the protocol going while
1764          * we do the initial computations.
1765          */
1766         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1767         packet_put_cstring(authctxt->server_user);
1768         packet_put_cstring(authctxt->service);
1769         packet_put_cstring(authctxt->method->name);
1770         packet_send();
1771         packet_write_wait();
1772
1773         jpake_step1(pctx->grp,
1774             &pctx->client_id, &pctx->client_id_len,
1775             &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2,
1776             &x1_proof, &x1_proof_len,
1777             &x2_proof, &x2_proof_len);
1778
1779         JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__));
1780
1781         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1);
1782         packet_put_string(pctx->client_id, pctx->client_id_len);
1783         packet_put_bignum2(pctx->g_x1);
1784         packet_put_bignum2(pctx->g_x2);
1785         packet_put_string(x1_proof, x1_proof_len);
1786         packet_put_string(x2_proof, x2_proof_len);
1787         packet_send();
1788
1789         bzero(x1_proof, x1_proof_len);
1790         bzero(x2_proof, x2_proof_len);
1791         xfree(x1_proof);
1792         xfree(x2_proof);
1793
1794         /* Expect step 1 packet from peer */
1795         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1,
1796             input_userauth_jpake_server_step1);
1797         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS,
1798             &input_userauth_success_unexpected);
1799
1800         return 1;
1801 }
1802
1803 void
1804 userauth_jpake_cleanup(Authctxt *authctxt)
1805 {
1806         debug3("%s: clean up", __func__);
1807         if (authctxt->methoddata != NULL) {
1808                 jpake_free(authctxt->methoddata);
1809                 authctxt->methoddata = NULL;
1810         }
1811         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
1812 }
1813 #endif /* JPAKE */
1814
1815 /* find auth method */
1816
1817 /*
1818  * given auth method name, if configurable options permit this method fill
1819  * in auth_ident field and return true, otherwise return false.
1820  */
1821 static int
1822 authmethod_is_enabled(Authmethod *method)
1823 {
1824         if (method == NULL)
1825                 return 0;
1826         /* return false if options indicate this method is disabled */
1827         if  (method->enabled == NULL || *method->enabled == 0)
1828                 return 0;
1829         /* return false if batch mode is enabled but method needs interactive mode */
1830         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1831                 return 0;
1832         return 1;
1833 }
1834
1835 static Authmethod *
1836 authmethod_lookup(const char *name)
1837 {
1838         Authmethod *method = NULL;
1839         if (name != NULL)
1840                 for (method = authmethods; method->name != NULL; method++)
1841                         if (strcmp(name, method->name) == 0)
1842                                 return method;
1843         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1844         return NULL;
1845 }
1846
1847 /* XXX internal state */
1848 static Authmethod *current = NULL;
1849 static char *supported = NULL;
1850 static char *preferred = NULL;
1851
1852 /*
1853  * Given the authentication method list sent by the server, return the
1854  * next method we should try.  If the server initially sends a nil list,
1855  * use a built-in default list.
1856  */
1857 static Authmethod *
1858 authmethod_get(char *authlist)
1859 {
1860         char *name = NULL;
1861         u_int next;
1862
1863         /* Use a suitable default if we're passed a nil list.  */
1864         if (authlist == NULL || strlen(authlist) == 0)
1865                 authlist = options.preferred_authentications;
1866
1867         if (supported == NULL || strcmp(authlist, supported) != 0) {
1868                 debug3("start over, passed a different list %s", authlist);
1869                 if (supported != NULL)
1870                         xfree(supported);
1871                 supported = xstrdup(authlist);
1872                 preferred = options.preferred_authentications;
1873                 debug3("preferred %s", preferred);
1874                 current = NULL;
1875         } else if (current != NULL && authmethod_is_enabled(current))
1876                 return current;
1877
1878         for (;;) {
1879                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1880                         debug("No more authentication methods to try.");
1881                         current = NULL;
1882                         return NULL;
1883                 }
1884                 preferred += next;
1885                 debug3("authmethod_lookup %s", name);
1886                 debug3("remaining preferred: %s", preferred);
1887                 if ((current = authmethod_lookup(name)) != NULL &&
1888                     authmethod_is_enabled(current)) {
1889                         debug3("authmethod_is_enabled %s", name);
1890                         debug("Next authentication method: %s", name);
1891                         return current;
1892                 }
1893         }
1894 }
1895
1896 static char *
1897 authmethods_get(void)
1898 {
1899         Authmethod *method = NULL;
1900         Buffer b;
1901         char *list;
1902
1903         buffer_init(&b);
1904         for (method = authmethods; method->name != NULL; method++) {
1905                 if (authmethod_is_enabled(method)) {
1906                         if (buffer_len(&b) > 0)
1907                                 buffer_append(&b, ",", 1);
1908                         buffer_append(&b, method->name, strlen(method->name));
1909                 }
1910         }
1911         buffer_append(&b, "\0", 1);
1912         list = xstrdup(buffer_ptr(&b));
1913         buffer_free(&b);
1914         return list;
1915 }
1916