sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.188 2011/05/24 07:15:47 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         u_int i;
 113
 114         /* Find all hostkeys for this hostname */
 115         get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
 116         hostkeys = init_hostkeys();
 117         for (i = 0; i < options.num_user_hostfiles; i++)
 118                 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]);
 119         for (i = 0; i < options.num_system_hostfiles; i++)
 120                 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]);
 121
 122         oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG);
 123         maxlen = strlen(avail) + 1;
 124         first = xmalloc(maxlen);
 125         last = xmalloc(maxlen);
 126         *first = *last = '\0';
 127
 128 #define ALG_APPEND(to, from) \
 129         do { \
 130                 if (*to != '\0') \
 131                         strlcat(to, ",", maxlen); \
 132                 strlcat(to, from, maxlen); \
 133         } while (0)
 134
 135         while ((alg = strsep(&avail, ",")) && *alg != '\0') {
 136                 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC)
 137                         fatal("%s: unknown alg %s", __func__, alg);
 138                 if (lookup_key_in_hostkeys_by_type(hostkeys,
 139                     key_type_plain(ktype), NULL))
 140                         ALG_APPEND(first, alg);
 141                 else
 142                         ALG_APPEND(last, alg);
 143         }
 144 #undef ALG_APPEND
 145         xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last);
 146         if (*first != '\0')
 147                 debug3("%s: prefer hostkeyalgs: %s", __func__, first);
 148
 149         xfree(first);
 150         xfree(last);
 151         xfree(hostname);
 152         xfree(oavail);
 153         free_hostkeys(hostkeys);
 154
 155         return ret;
 156 }
 157
 158 void
 159 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
 160 {
 161         Kex *kex;
 162
 163         xxx_host = host;
 164         xxx_hostaddr = hostaddr;
 165
 166         if (options.ciphers == (char *)-1) {
 167                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 168                 options.ciphers = NULL;
 169         }
 170         if (options.ciphers != NULL) {
 171                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 172                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 173         }
 174         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 175             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 176         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 177             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 178         if (options.compression) {
 179                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 180                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 181         } else {
 182                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 183                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 184         }
 185         if (options.macs != NULL) {
 186                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 187                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 188         }
 189         if (options.hostkeyalgorithms != NULL)
 190                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 191                     options.hostkeyalgorithms;
 192         else {
 193                 /* Prefer algorithms that we already have keys for */
 194                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 195                     order_hostkeyalgs(host, hostaddr, port);
 196         }
 197         if (options.kex_algorithms != NULL)
 198                 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
 199
 200         if (options.rekey_limit)
 201                 packet_set_rekey_limit((u_int32_t)options.rekey_limit);
 202
 203         /* start key exchange */
 204         kex = kex_setup(myproposal);
 205         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 206         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 207         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 208         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 209         kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
 210         kex->client_version_string=client_version_string;
 211         kex->server_version_string=server_version_string;
 212         kex->verify_host_key=&verify_host_key_callback;
 213
 214         xxx_kex = kex;
 215
 216         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 217
 218         if (options.use_roaming && !kex->roaming) {
 219                 debug("Roaming not allowed by server");
 220                 options.use_roaming = 0;
 221         }
 222
 223         session_id2 = kex->session_id;
 224         session_id2_len = kex->session_id_len;
 225
 226 #ifdef DEBUG_KEXDH
 227         /* send 1st encrypted/maced/compressed message */
 228         packet_start(SSH2_MSG_IGNORE);
 229         packet_put_cstring("markus");
 230         packet_send();
 231         packet_write_wait();
 232 #endif
 233 }
 234
 235 /*
 236  * Authenticate user
 237  */
 238
 239 typedef struct Authctxt Authctxt;
 240 typedef struct Authmethod Authmethod;
 241 typedef struct identity Identity;
 242 typedef struct idlist Idlist;
 243
 244 struct identity {
 245         TAILQ_ENTRY(identity) next;
 246         AuthenticationConnection *ac;   /* set if agent supports key */
 247         Key     *key;                   /* public/private key */
 248         char    *filename;              /* comment for agent-only keys */
 249         int     tried;
 250         int     isprivate;              /* key points to the private key */
 251 };
 252 TAILQ_HEAD(idlist, identity);
 253
 254 struct Authctxt {
 255         const char *server_user;
 256         const char *local_user;
 257         const char *host;
 258         const char *service;
 259         Authmethod *method;
 260         sig_atomic_t success;
 261         char *authlist;
 262         /* pubkey */
 263         Idlist keys;
 264         AuthenticationConnection *agent;
 265         /* hostbased */
 266         Sensitive *sensitive;
 267         /* kbd-interactive */
 268         int info_req_seen;
 269         /* generic */
 270         void *methoddata;
 271 };
 272 struct Authmethod {
 273         char    *name;          /* string to compare against server's list */
 274         int     (*userauth)(Authctxt *authctxt);
 275         void    (*cleanup)(Authctxt *authctxt);
 276         int     *enabled;       /* flag in option struct that enables method */
 277         int     *batch_flag;    /* flag in option struct that disables method */
 278 };
 279
 280 void    input_userauth_success(int, u_int32_t, void *);
 281 void    input_userauth_success_unexpected(int, u_int32_t, void *);
 282 void    input_userauth_failure(int, u_int32_t, void *);
 283 void    input_userauth_banner(int, u_int32_t, void *);
 284 void    input_userauth_error(int, u_int32_t, void *);
 285 void    input_userauth_info_req(int, u_int32_t, void *);
 286 void    input_userauth_pk_ok(int, u_int32_t, void *);
 287 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 288 void    input_userauth_jpake_server_step1(int, u_int32_t, void *);
 289 void    input_userauth_jpake_server_step2(int, u_int32_t, void *);
 290 void    input_userauth_jpake_server_confirm(int, u_int32_t, void *);
 291
 292 int     userauth_none(Authctxt *);
 293 int     userauth_pubkey(Authctxt *);
 294 int     userauth_passwd(Authctxt *);
 295 int     userauth_kbdint(Authctxt *);
 296 int     userauth_hostbased(Authctxt *);
 297 int     userauth_jpake(Authctxt *);
 298
 299 void    userauth_jpake_cleanup(Authctxt *);
 300
 301 #ifdef GSSAPI
 302 int     userauth_gssapi(Authctxt *authctxt);
 303 void    input_gssapi_response(int type, u_int32_t, void *);
 304 void    input_gssapi_token(int type, u_int32_t, void *);
 305 void    input_gssapi_hash(int type, u_int32_t, void *);
 306 void    input_gssapi_error(int, u_int32_t, void *);
 307 void    input_gssapi_errtok(int, u_int32_t, void *);
 308 #endif
 309
 310 void    userauth(Authctxt *, char *);
 311
 312 static int sign_and_send_pubkey(Authctxt *, Identity *);
 313 static void pubkey_prepare(Authctxt *);
 314 static void pubkey_cleanup(Authctxt *);
 315 static Key *load_identity_file(char *);
 316
 317 static Authmethod *authmethod_get(char *authlist);
 318 static Authmethod *authmethod_lookup(const char *name);
 319 static char *authmethods_get(void);
 320
 321 Authmethod authmethods[] = {
 322 #ifdef GSSAPI
 323         {"gssapi-with-mic",
 324                 userauth_gssapi,
 325                 NULL,
 326                 &options.gss_authentication,
 327                 NULL},
 328 #endif
 329         {"hostbased",
 330                 userauth_hostbased,
 331                 NULL,
 332                 &options.hostbased_authentication,
 333                 NULL},
 334         {"publickey",
 335                 userauth_pubkey,
 336                 NULL,
 337                 &options.pubkey_authentication,
 338                 NULL},
 339 #ifdef JPAKE
 340         {"jpake-01@openssh.com",
 341                 userauth_jpake,
 342                 userauth_jpake_cleanup,
 343                 &options.zero_knowledge_password_authentication,
 344                 &options.batch_mode},
 345 #endif
 346         {"keyboard-interactive",
 347                 userauth_kbdint,
 348                 NULL,
 349                 &options.kbd_interactive_authentication,
 350                 &options.batch_mode},
 351         {"password",
 352                 userauth_passwd,
 353                 NULL,
 354                 &options.password_authentication,
 355                 &options.batch_mode},
 356         {"none",
 357                 userauth_none,
 358                 NULL,
 359                 NULL,
 360                 NULL},
 361         {NULL, NULL, NULL, NULL, NULL}
 362 };
 363
 364 void
 365 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 366     Sensitive *sensitive)
 367 {
 368         Authctxt authctxt;
 369         int type;
 370
 371         if (options.challenge_response_authentication)
 372                 options.kbd_interactive_authentication = 1;
 373
 374         packet_start(SSH2_MSG_SERVICE_REQUEST);
 375         packet_put_cstring("ssh-userauth");
 376         packet_send();
 377         debug("SSH2_MSG_SERVICE_REQUEST sent");
 378         packet_write_wait();
 379         type = packet_read();
 380         if (type != SSH2_MSG_SERVICE_ACCEPT)
 381                 fatal("Server denied authentication request: %d", type);
 382         if (packet_remaining() > 0) {
 383                 char *reply = packet_get_string(NULL);
 384                 debug2("service_accept: %s", reply);
 385                 xfree(reply);
 386         } else {
 387                 debug2("buggy server: service_accept w/o service");
 388         }
 389         packet_check_eom();
 390         debug("SSH2_MSG_SERVICE_ACCEPT received");
 391
 392         if (options.preferred_authentications == NULL)
 393                 options.preferred_authentications = authmethods_get();
 394
 395         /* setup authentication context */
 396         memset(&authctxt, 0, sizeof(authctxt));
 397         pubkey_prepare(&authctxt);
 398         authctxt.server_user = server_user;
 399         authctxt.local_user = local_user;
 400         authctxt.host = host;
 401         authctxt.service = "ssh-connection";            /* service name */
 402         authctxt.success = 0;
 403         authctxt.method = authmethod_lookup("none");
 404         authctxt.authlist = NULL;
 405         authctxt.methoddata = NULL;
 406         authctxt.sensitive = sensitive;
 407         authctxt.info_req_seen = 0;
 408         if (authctxt.method == NULL)
 409                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 410
 411         /* initial userauth request */
 412         userauth_none(&authctxt);
 413
 414         dispatch_init(&input_userauth_error);
 415         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 416         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 417         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 418         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 419
 420         pubkey_cleanup(&authctxt);
 421         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 422
 423         debug("Authentication succeeded (%s).", authctxt.method->name);
 424 }
 425
 426 void
 427 userauth(Authctxt *authctxt, char *authlist)
 428 {
 429         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 430                 authctxt->method->cleanup(authctxt);
 431
 432         if (authctxt->methoddata) {
 433                 xfree(authctxt->methoddata);
 434                 authctxt->methoddata = NULL;
 435         }
 436         if (authlist == NULL) {
 437                 authlist = authctxt->authlist;
 438         } else {
 439                 if (authctxt->authlist)
 440                         xfree(authctxt->authlist);
 441                 authctxt->authlist = authlist;
 442         }
 443         for (;;) {
 444                 Authmethod *method = authmethod_get(authlist);
 445                 if (method == NULL)
 446                         fatal("Permission denied (%s).", authlist);
 447                 authctxt->method = method;
 448
 449                 /* reset the per method handler */
 450                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 451                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 452
 453                 /* and try new method */
 454                 if (method->userauth(authctxt) != 0) {
 455                         debug2("we sent a %s packet, wait for reply", method->name);
 456                         break;
 457                 } else {
 458                         debug2("we did not send a packet, disable method");
 459                         method->enabled = NULL;
 460                 }
 461         }
 462 }
 463
 464 /* ARGSUSED */
 465 void
 466 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 467 {
 468         fatal("input_userauth_error: bad message during authentication: "
 469             "type %d", type);
 470 }
 471
 472 /* ARGSUSED */
 473 void
 474 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 475 {
 476         char *msg, *raw, *lang;
 477         u_int len;
 478
 479         debug3("input_userauth_banner");
 480         raw = packet_get_string(&len);
 481         lang = packet_get_string(NULL);
 482         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
 483                 if (len > 65536)
 484                         len = 65536;
 485                 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
 486                 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH);
 487                 fprintf(stderr, "%s", msg);
 488                 xfree(msg);
 489         }
 490         xfree(raw);
 491         xfree(lang);
 492 }
 493
 494 /* ARGSUSED */
 495 void
 496 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 497 {
 498         Authctxt *authctxt = ctxt;
 499
 500         if (authctxt == NULL)
 501                 fatal("input_userauth_success: no authentication context");
 502         if (authctxt->authlist) {
 503                 xfree(authctxt->authlist);
 504                 authctxt->authlist = NULL;
 505         }
 506         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 507                 authctxt->method->cleanup(authctxt);
 508         if (authctxt->methoddata) {
 509                 xfree(authctxt->methoddata);
 510                 authctxt->methoddata = NULL;
 511         }
 512         authctxt->success = 1;                  /* break out */
 513 }
 514
 515 void
 516 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
 517 {
 518         Authctxt *authctxt = ctxt;
 519
 520         if (authctxt == NULL)
 521                 fatal("%s: no authentication context", __func__);
 522
 523         fatal("Unexpected authentication success during %s.",
 524             authctxt->method->name);
 525 }
 526
 527 /* ARGSUSED */
 528 void
 529 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 530 {
 531         Authctxt *authctxt = ctxt;
 532         char *authlist = NULL;
 533         int partial;
 534
 535         if (authctxt == NULL)
 536                 fatal("input_userauth_failure: no authentication context");
 537
 538         authlist = packet_get_string(NULL);
 539         partial = packet_get_char();
 540         packet_check_eom();
 541
 542         if (partial != 0)
 543                 logit("Authenticated with partial success.");
 544         debug("Authentications that can continue: %s", authlist);
 545
 546         userauth(authctxt, authlist);
 547 }
 548
 549 /* ARGSUSED */
 550 void
 551 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 552 {
 553         Authctxt *authctxt = ctxt;
 554         Key *key = NULL;
 555         Identity *id = NULL;
 556         Buffer b;
 557         int pktype, sent = 0;
 558         u_int alen, blen;
 559         char *pkalg, *fp;
 560         u_char *pkblob;
 561
 562         if (authctxt == NULL)
 563                 fatal("input_userauth_pk_ok: no authentication context");
 564         if (datafellows & SSH_BUG_PKOK) {
 565                 /* this is similar to SSH_BUG_PKAUTH */
 566                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 567                 pkblob = packet_get_string(&blen);
 568                 buffer_init(&b);
 569                 buffer_append(&b, pkblob, blen);
 570                 pkalg = buffer_get_string(&b, &alen);
 571                 buffer_free(&b);
 572         } else {
 573                 pkalg = packet_get_string(&alen);
 574                 pkblob = packet_get_string(&blen);
 575         }
 576         packet_check_eom();
 577
 578         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 579
 580         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 581                 debug("unknown pkalg %s", pkalg);
 582                 goto done;
 583         }
 584         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 585                 debug("no key from blob. pkalg %s", pkalg);
 586                 goto done;
 587         }
 588         if (key->type != pktype) {
 589                 error("input_userauth_pk_ok: type mismatch "
 590                     "for decoded key (received %d, expected %d)",
 591                     key->type, pktype);
 592                 goto done;
 593         }
 594         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 595         debug2("input_userauth_pk_ok: fp %s", fp);
 596         xfree(fp);
 597
 598         /*
 599          * search keys in the reverse order, because last candidate has been
 600          * moved to the end of the queue.  this also avoids confusion by
 601          * duplicate keys
 602          */
 603         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 604                 if (key_equal(key, id->key)) {
 605                         sent = sign_and_send_pubkey(authctxt, id);
 606                         break;
 607                 }
 608         }
 609 done:
 610         if (key != NULL)
 611                 key_free(key);
 612         xfree(pkalg);
 613         xfree(pkblob);
 614
 615         /* try another method if we did not send a packet */
 616         if (sent == 0)
 617                 userauth(authctxt, NULL);
 618 }
 619
 620 #ifdef GSSAPI
 621 int
 622 userauth_gssapi(Authctxt *authctxt)
 623 {
 624         Gssctxt *gssctxt = NULL;
 625         static gss_OID_set gss_supported = NULL;
 626         static u_int mech = 0;
 627         OM_uint32 min;
 628         int ok = 0;
 629
 630         /* Try one GSSAPI method at a time, rather than sending them all at
 631          * once. */
 632
 633         if (gss_supported == NULL)
 634                 gss_indicate_mechs(&min, &gss_supported);
 635
 636         /* Check to see if the mechanism is usable before we offer it */
 637         while (mech < gss_supported->count && !ok) {
 638                 /* My DER encoding requires length<128 */
 639                 if (gss_supported->elements[mech].length < 128 &&
 640                     ssh_gssapi_check_mechanism(&gssctxt,
 641                     &gss_supported->elements[mech], authctxt->host)) {
 642                         ok = 1; /* Mechanism works */
 643                 } else {
 644                         mech++;
 645                 }
 646         }
 647
 648         if (!ok)
 649                 return 0;
 650
 651         authctxt->methoddata=(void *)gssctxt;
 652
 653         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 654         packet_put_cstring(authctxt->server_user);
 655         packet_put_cstring(authctxt->service);
 656         packet_put_cstring(authctxt->method->name);
 657
 658         packet_put_int(1);
 659
 660         packet_put_int((gss_supported->elements[mech].length) + 2);
 661         packet_put_char(SSH_GSS_OIDTYPE);
 662         packet_put_char(gss_supported->elements[mech].length);
 663         packet_put_raw(gss_supported->elements[mech].elements,
 664             gss_supported->elements[mech].length);
 665
 666         packet_send();
 667
 668         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 669         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 670         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 671         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 672
 673         mech++; /* Move along to next candidate */
 674
 675         return 1;
 676 }
 677
 678 static OM_uint32
 679 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 680 {
 681         Authctxt *authctxt = ctxt;
 682         Gssctxt *gssctxt = authctxt->methoddata;
 683         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 684         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 685         gss_buffer_desc gssbuf;
 686         OM_uint32 status, ms, flags;
 687         Buffer b;
 688
 689         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 690             recv_tok, &send_tok, &flags);
 691
 692         if (send_tok.length > 0) {
 693                 if (GSS_ERROR(status))
 694                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 695                 else
 696                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 697
 698                 packet_put_string(send_tok.value, send_tok.length);
 699                 packet_send();
 700                 gss_release_buffer(&ms, &send_tok);
 701         }
 702
 703         if (status == GSS_S_COMPLETE) {
 704                 /* send either complete or MIC, depending on mechanism */
 705                 if (!(flags & GSS_C_INTEG_FLAG)) {
 706                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 707                         packet_send();
 708                 } else {
 709                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 710                             authctxt->service, "gssapi-with-mic");
 711
 712                         gssbuf.value = buffer_ptr(&b);
 713                         gssbuf.length = buffer_len(&b);
 714
 715                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 716
 717                         if (!GSS_ERROR(status)) {
 718                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 719                                 packet_put_string(mic.value, mic.length);
 720
 721                                 packet_send();
 722                         }
 723
 724                         buffer_free(&b);
 725                         gss_release_buffer(&ms, &mic);
 726                 }
 727         }
 728
 729         return status;
 730 }
 731
 732 /* ARGSUSED */
 733 void
 734 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 735 {
 736         Authctxt *authctxt = ctxt;
 737         Gssctxt *gssctxt;
 738         int oidlen;
 739         char *oidv;
 740
 741         if (authctxt == NULL)
 742                 fatal("input_gssapi_response: no authentication context");
 743         gssctxt = authctxt->methoddata;
 744
 745         /* Setup our OID */
 746         oidv = packet_get_string(&oidlen);
 747
 748         if (oidlen <= 2 ||
 749             oidv[0] != SSH_GSS_OIDTYPE ||
 750             oidv[1] != oidlen - 2) {
 751                 xfree(oidv);
 752                 debug("Badly encoded mechanism OID received");
 753                 userauth(authctxt, NULL);
 754                 return;
 755         }
 756
 757         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 758                 fatal("Server returned different OID than expected");
 759
 760         packet_check_eom();
 761
 762         xfree(oidv);
 763
 764         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 765                 /* Start again with next method on list */
 766                 debug("Trying to start again");
 767                 userauth(authctxt, NULL);
 768                 return;
 769         }
 770 }
 771
 772 /* ARGSUSED */
 773 void
 774 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 775 {
 776         Authctxt *authctxt = ctxt;
 777         gss_buffer_desc recv_tok;
 778         OM_uint32 status;
 779         u_int slen;
 780
 781         if (authctxt == NULL)
 782                 fatal("input_gssapi_response: no authentication context");
 783
 784         recv_tok.value = packet_get_string(&slen);
 785         recv_tok.length = slen; /* safe typecast */
 786
 787         packet_check_eom();
 788
 789         status = process_gssapi_token(ctxt, &recv_tok);
 790
 791         xfree(recv_tok.value);
 792
 793         if (GSS_ERROR(status)) {
 794                 /* Start again with the next method in the list */
 795                 userauth(authctxt, NULL);
 796                 return;
 797         }
 798 }
 799
 800 /* ARGSUSED */
 801 void
 802 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 803 {
 804         Authctxt *authctxt = ctxt;
 805         Gssctxt *gssctxt;
 806         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 807         gss_buffer_desc recv_tok;
 808         OM_uint32 status, ms;
 809         u_int len;
 810
 811         if (authctxt == NULL)
 812                 fatal("input_gssapi_response: no authentication context");
 813         gssctxt = authctxt->methoddata;
 814
 815         recv_tok.value = packet_get_string(&len);
 816         recv_tok.length = len;
 817
 818         packet_check_eom();
 819
 820         /* Stick it into GSSAPI and see what it says */
 821         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 822             &recv_tok, &send_tok, NULL);
 823
 824         xfree(recv_tok.value);
 825         gss_release_buffer(&ms, &send_tok);
 826
 827         /* Server will be returning a failed packet after this one */
 828 }
 829
 830 /* ARGSUSED */
 831 void
 832 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 833 {
 834         OM_uint32 maj, min;
 835         char *msg;
 836         char *lang;
 837
 838         maj=packet_get_int();
 839         min=packet_get_int();
 840         msg=packet_get_string(NULL);
 841         lang=packet_get_string(NULL);
 842
 843         packet_check_eom();
 844
 845         debug("Server GSSAPI Error:\n%s", msg);
 846         xfree(msg);
 847         xfree(lang);
 848 }
 849 #endif /* GSSAPI */
 850
 851 int
 852 userauth_none(Authctxt *authctxt)
 853 {
 854         /* initial userauth request */
 855         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 856         packet_put_cstring(authctxt->server_user);
 857         packet_put_cstring(authctxt->service);
 858         packet_put_cstring(authctxt->method->name);
 859         packet_send();
 860         return 1;
 861 }
 862
 863 int
 864 userauth_passwd(Authctxt *authctxt)
 865 {
 866         static int attempt = 0;
 867         char prompt[150];
 868         char *password;
 869         const char *host = options.host_key_alias ?  options.host_key_alias :
 870             authctxt->host;
 871
 872         if (attempt++ >= options.number_of_password_prompts)
 873                 return 0;
 874
 875         if (attempt != 1)
 876                 error("Permission denied, please try again.");
 877
 878         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 879             authctxt->server_user, host);
 880         password = read_passphrase(prompt, 0);
 881         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 882         packet_put_cstring(authctxt->server_user);
 883         packet_put_cstring(authctxt->service);
 884         packet_put_cstring(authctxt->method->name);
 885         packet_put_char(0);
 886         packet_put_cstring(password);
 887         memset(password, 0, strlen(password));
 888         xfree(password);
 889         packet_add_padding(64);
 890         packet_send();
 891
 892         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 893             &input_userauth_passwd_changereq);
 894
 895         return 1;
 896 }
 897
 898 /*
 899  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 900  */
 901 /* ARGSUSED */
 902 void
 903 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 904 {
 905         Authctxt *authctxt = ctxt;
 906         char *info, *lang, *password = NULL, *retype = NULL;
 907         char prompt[150];
 908         const char *host = options.host_key_alias ? options.host_key_alias :
 909             authctxt->host;
 910
 911         debug2("input_userauth_passwd_changereq");
 912
 913         if (authctxt == NULL)
 914                 fatal("input_userauth_passwd_changereq: "
 915                     "no authentication context");
 916
 917         info = packet_get_string(NULL);
 918         lang = packet_get_string(NULL);
 919         if (strlen(info) > 0)
 920                 logit("%s", info);
 921         xfree(info);
 922         xfree(lang);
 923         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 924         packet_put_cstring(authctxt->server_user);
 925         packet_put_cstring(authctxt->service);
 926         packet_put_cstring(authctxt->method->name);
 927         packet_put_char(1);                     /* additional info */
 928         snprintf(prompt, sizeof(prompt),
 929             "Enter %.30s@%.128s's old password: ",
 930             authctxt->server_user, host);
 931         password = read_passphrase(prompt, 0);
 932         packet_put_cstring(password);
 933         memset(password, 0, strlen(password));
 934         xfree(password);
 935         password = NULL;
 936         while (password == NULL) {
 937                 snprintf(prompt, sizeof(prompt),
 938                     "Enter %.30s@%.128s's new password: ",
 939                     authctxt->server_user, host);
 940                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 941                 if (password == NULL) {
 942                         /* bail out */
 943                         return;
 944                 }
 945                 snprintf(prompt, sizeof(prompt),
 946                     "Retype %.30s@%.128s's new password: ",
 947                     authctxt->server_user, host);
 948                 retype = read_passphrase(prompt, 0);
 949                 if (strcmp(password, retype) != 0) {
 950                         memset(password, 0, strlen(password));
 951                         xfree(password);
 952                         logit("Mismatch; try again, EOF to quit.");
 953                         password = NULL;
 954                 }
 955                 memset(retype, 0, strlen(retype));
 956                 xfree(retype);
 957         }
 958         packet_put_cstring(password);
 959         memset(password, 0, strlen(password));
 960         xfree(password);
 961         packet_add_padding(64);
 962         packet_send();
 963
 964         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 965             &input_userauth_passwd_changereq);
 966 }
 967
 968 #ifdef JPAKE
 969 static char *
 970 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt)
 971 {
 972         /* OpenBSD crypt(3) handles all of these */
 973         if (strcmp(crypt_scheme, "crypt") == 0 ||
 974             strcmp(crypt_scheme, "bcrypt") == 0 ||
 975             strcmp(crypt_scheme, "md5crypt") == 0 ||
 976             strcmp(crypt_scheme, "crypt-extended") == 0)
 977                 return xstrdup(crypt(password, salt));
 978         error("%s: unsupported password encryption scheme \"%.100s\"",
 979             __func__, crypt_scheme);
 980         return NULL;
 981 }
 982
 983 static BIGNUM *
 984 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme,
 985     const char *salt)
 986 {
 987         char prompt[256], *password, *crypted;
 988         u_char *secret;
 989         u_int secret_len;
 990         BIGNUM *ret;
 991
 992         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ",
 993             authctxt->server_user, authctxt->host);
 994         password = read_passphrase(prompt, 0);
 995
 996         if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) {
 997                 logit("Disabling %s authentication", authctxt->method->name);
 998                 authctxt->method->enabled = NULL;
 999                 /* Continue with an empty password to fail gracefully */
1000                 crypted = xstrdup("");
1001         }
1002
1003 #ifdef JPAKE_DEBUG
1004         debug3("%s: salt = %s", __func__, salt);
1005         debug3("%s: scheme = %s", __func__, crypt_scheme);
1006         debug3("%s: crypted = %s", __func__, crypted);
1007 #endif
1008
1009         if (hash_buffer(crypted, strlen(crypted), EVP_sha256(),
1010             &secret, &secret_len) != 0)
1011                 fatal("%s: hash_buffer", __func__);
1012
1013         bzero(password, strlen(password));
1014         bzero(crypted, strlen(crypted));
1015         xfree(password);
1016         xfree(crypted);
1017
1018         if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL)
1019                 fatal("%s: BN_bin2bn (secret)", __func__);
1020         bzero(secret, secret_len);
1021         xfree(secret);
1022
1023         return ret;
1024 }
1025
1026 /* ARGSUSED */
1027 void
1028 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt)
1029 {
1030         Authctxt *authctxt = ctxt;
1031         struct jpake_ctx *pctx = authctxt->methoddata;
1032         u_char *x3_proof, *x4_proof, *x2_s_proof;
1033         u_int x3_proof_len, x4_proof_len, x2_s_proof_len;
1034         char *crypt_scheme, *salt;
1035
1036         /* Disable this message */
1037         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL);
1038
1039         if ((pctx->g_x3 = BN_new()) == NULL ||
1040             (pctx->g_x4 = BN_new()) == NULL)
1041                 fatal("%s: BN_new", __func__);
1042
1043         /* Fetch step 1 values */
1044         crypt_scheme = packet_get_string(NULL);
1045         salt = packet_get_string(NULL);
1046         pctx->server_id = packet_get_string(&pctx->server_id_len);
1047         packet_get_bignum2(pctx->g_x3);
1048         packet_get_bignum2(pctx->g_x4);
1049         x3_proof = packet_get_string(&x3_proof_len);
1050         x4_proof = packet_get_string(&x4_proof_len);
1051         packet_check_eom();
1052
1053         JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__));
1054
1055         /* Obtain password and derive secret */
1056         pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt);
1057         bzero(crypt_scheme, strlen(crypt_scheme));
1058         bzero(salt, strlen(salt));
1059         xfree(crypt_scheme);
1060         xfree(salt);
1061         JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__));
1062
1063         /* Calculate step 2 values */
1064         jpake_step2(pctx->grp, pctx->s, pctx->g_x1,
1065             pctx->g_x3, pctx->g_x4, pctx->x2,
1066             pctx->server_id, pctx->server_id_len,
1067             pctx->client_id, pctx->client_id_len,
1068             x3_proof, x3_proof_len,
1069             x4_proof, x4_proof_len,
1070             &pctx->a,
1071             &x2_s_proof, &x2_s_proof_len);
1072
1073         bzero(x3_proof, x3_proof_len);
1074         bzero(x4_proof, x4_proof_len);
1075         xfree(x3_proof);
1076         xfree(x4_proof);
1077
1078         JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__));
1079
1080         /* Send values for step 2 */
1081         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2);
1082         packet_put_bignum2(pctx->a);
1083         packet_put_string(x2_s_proof, x2_s_proof_len);
1084         packet_send();
1085
1086         bzero(x2_s_proof, x2_s_proof_len);
1087         xfree(x2_s_proof);
1088
1089         /* Expect step 2 packet from peer */
1090         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2,
1091             input_userauth_jpake_server_step2);
1092 }
1093
1094 /* ARGSUSED */
1095 void
1096 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt)
1097 {
1098         Authctxt *authctxt = ctxt;
1099         struct jpake_ctx *pctx = authctxt->methoddata;
1100         u_char *x4_s_proof;
1101         u_int x4_s_proof_len;
1102
1103         /* Disable this message */
1104         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL);
1105
1106         if ((pctx->b = BN_new()) == NULL)
1107                 fatal("%s: BN_new", __func__);
1108
1109         /* Fetch step 2 values */
1110         packet_get_bignum2(pctx->b);
1111         x4_s_proof = packet_get_string(&x4_s_proof_len);
1112         packet_check_eom();
1113
1114         JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__));
1115
1116         /* Derive shared key and calculate confirmation hash */
1117         jpake_key_confirm(pctx->grp, pctx->s, pctx->b,
1118             pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4,
1119             pctx->client_id, pctx->client_id_len,
1120             pctx->server_id, pctx->server_id_len,
1121             session_id2, session_id2_len,
1122             x4_s_proof, x4_s_proof_len,
1123             &pctx->k,
1124             &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len);
1125
1126         bzero(x4_s_proof, x4_s_proof_len);
1127         xfree(x4_s_proof);
1128
1129         JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__));
1130
1131         /* Send key confirmation proof */
1132         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM);
1133         packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len);
1134         packet_send();
1135
1136         /* Expect confirmation from peer */
1137         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM,
1138             input_userauth_jpake_server_confirm);
1139 }
1140
1141 /* ARGSUSED */
1142 void
1143 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt)
1144 {
1145         Authctxt *authctxt = ctxt;
1146         struct jpake_ctx *pctx = authctxt->methoddata;
1147
1148         /* Disable this message */
1149         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL);
1150
1151         pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len);
1152         packet_check_eom();
1153
1154         JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__));
1155
1156         /* Verify expected confirmation hash */
1157         if (jpake_check_confirm(pctx->k,
1158             pctx->server_id, pctx->server_id_len,
1159             session_id2, session_id2_len,
1160             pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1)
1161                 debug("%s: %s success", __func__, authctxt->method->name);
1162         else {
1163                 debug("%s: confirmation mismatch", __func__);
1164                 /* XXX stash this so if auth succeeds then we can warn/kill */
1165         }
1166
1167         userauth_jpake_cleanup(authctxt);
1168 }
1169 #endif /* JPAKE */
1170
1171 static int
1172 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
1173     u_char *data, u_int datalen)
1174 {
1175         Key *prv;
1176         int ret;
1177
1178         /* the agent supports this key */
1179         if (id->ac)
1180                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1181                     data, datalen));
1182         /*
1183          * we have already loaded the private key or
1184          * the private key is stored in external hardware
1185          */
1186         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1187                 return (key_sign(id->key, sigp, lenp, data, datalen));
1188         /* load the private key from the file */
1189         if ((prv = load_identity_file(id->filename)) == NULL)
1190                 return (-1);
1191         ret = key_sign(prv, sigp, lenp, data, datalen);
1192         key_free(prv);
1193         return (ret);
1194 }
1195
1196 static int
1197 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1198 {
1199         Buffer b;
1200         u_char *blob, *signature;
1201         u_int bloblen, slen;
1202         u_int skip = 0;
1203         int ret = -1;
1204         int have_sig = 1;
1205         char *fp;
1206
1207         fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
1208         debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp);
1209         xfree(fp);
1210
1211         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1212                 /* we cannot handle this key */
1213                 debug3("sign_and_send_pubkey: cannot handle key");
1214                 return 0;
1215         }
1216         /* data to be signed */
1217         buffer_init(&b);
1218         if (datafellows & SSH_OLD_SESSIONID) {
1219                 buffer_append(&b, session_id2, session_id2_len);
1220                 skip = session_id2_len;
1221         } else {
1222                 buffer_put_string(&b, session_id2, session_id2_len);
1223                 skip = buffer_len(&b);
1224         }
1225         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1226         buffer_put_cstring(&b, authctxt->server_user);
1227         buffer_put_cstring(&b,
1228             datafellows & SSH_BUG_PKSERVICE ?
1229             "ssh-userauth" :
1230             authctxt->service);
1231         if (datafellows & SSH_BUG_PKAUTH) {
1232                 buffer_put_char(&b, have_sig);
1233         } else {
1234                 buffer_put_cstring(&b, authctxt->method->name);
1235                 buffer_put_char(&b, have_sig);
1236                 buffer_put_cstring(&b, key_ssh_name(id->key));
1237         }
1238         buffer_put_string(&b, blob, bloblen);
1239
1240         /* generate signature */
1241         ret = identity_sign(id, &signature, &slen,
1242             buffer_ptr(&b), buffer_len(&b));
1243         if (ret == -1) {
1244                 xfree(blob);
1245                 buffer_free(&b);
1246                 return 0;
1247         }
1248 #ifdef DEBUG_PK
1249         buffer_dump(&b);
1250 #endif
1251         if (datafellows & SSH_BUG_PKSERVICE) {
1252                 buffer_clear(&b);
1253                 buffer_append(&b, session_id2, session_id2_len);
1254                 skip = session_id2_len;
1255                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1256                 buffer_put_cstring(&b, authctxt->server_user);
1257                 buffer_put_cstring(&b, authctxt->service);
1258                 buffer_put_cstring(&b, authctxt->method->name);
1259                 buffer_put_char(&b, have_sig);
1260                 if (!(datafellows & SSH_BUG_PKAUTH))
1261                         buffer_put_cstring(&b, key_ssh_name(id->key));
1262                 buffer_put_string(&b, blob, bloblen);
1263         }
1264         xfree(blob);
1265
1266         /* append signature */
1267         buffer_put_string(&b, signature, slen);
1268         xfree(signature);
1269
1270         /* skip session id and packet type */
1271         if (buffer_len(&b) < skip + 1)
1272                 fatal("userauth_pubkey: internal error");
1273         buffer_consume(&b, skip + 1);
1274
1275         /* put remaining data from buffer into packet */
1276         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1277         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1278         buffer_free(&b);
1279         packet_send();
1280
1281         return 1;
1282 }
1283
1284 static int
1285 send_pubkey_test(Authctxt *authctxt, Identity *id)
1286 {
1287         u_char *blob;
1288         u_int bloblen, have_sig = 0;
1289
1290         debug3("send_pubkey_test");
1291
1292         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1293                 /* we cannot handle this key */
1294                 debug3("send_pubkey_test: cannot handle key");
1295                 return 0;
1296         }
1297         /* register callback for USERAUTH_PK_OK message */
1298         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1299
1300         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1301         packet_put_cstring(authctxt->server_user);
1302         packet_put_cstring(authctxt->service);
1303         packet_put_cstring(authctxt->method->name);
1304         packet_put_char(have_sig);
1305         if (!(datafellows & SSH_BUG_PKAUTH))
1306                 packet_put_cstring(key_ssh_name(id->key));
1307         packet_put_string(blob, bloblen);
1308         xfree(blob);
1309         packet_send();
1310         return 1;
1311 }
1312
1313 static Key *
1314 load_identity_file(char *filename)
1315 {
1316         Key *private;
1317         char prompt[300], *passphrase;
1318         int perm_ok = 0, quit, i;
1319         struct stat st;
1320
1321         if (stat(filename, &st) < 0) {
1322                 debug3("no such identity: %s", filename);
1323                 return NULL;
1324         }
1325         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1326         if (!perm_ok)
1327                 return NULL;
1328         if (private == NULL) {
1329                 if (options.batch_mode)
1330                         return NULL;
1331                 snprintf(prompt, sizeof prompt,
1332                     "Enter passphrase for key '%.100s': ", filename);
1333                 for (i = 0; i < options.number_of_password_prompts; i++) {
1334                         passphrase = read_passphrase(prompt, 0);
1335                         if (strcmp(passphrase, "") != 0) {
1336                                 private = key_load_private_type(KEY_UNSPEC,
1337                                     filename, passphrase, NULL, NULL);
1338                                 quit = 0;
1339                         } else {
1340                                 debug2("no passphrase given, try next key");
1341                                 quit = 1;
1342                         }
1343                         memset(passphrase, 0, strlen(passphrase));
1344                         xfree(passphrase);
1345                         if (private != NULL || quit)
1346                                 break;
1347                         debug2("bad passphrase given, try again...");
1348                 }
1349         }
1350         return private;
1351 }
1352
1353 /*
1354  * try keys in the following order:
1355  *      1. agent keys that are found in the config file
1356  *      2. other agent keys
1357  *      3. keys that are only listed in the config file
1358  */
1359 static void
1360 pubkey_prepare(Authctxt *authctxt)
1361 {
1362         Identity *id;
1363         Idlist agent, files, *preferred;
1364         Key *key;
1365         AuthenticationConnection *ac;
1366         char *comment;
1367         int i, found;
1368
1369         TAILQ_INIT(&agent);     /* keys from the agent */
1370         TAILQ_INIT(&files);     /* keys from the config file */
1371         preferred = &authctxt->keys;
1372         TAILQ_INIT(preferred);  /* preferred order of keys */
1373
1374         /* list of keys stored in the filesystem */
1375         for (i = 0; i < options.num_identity_files; i++) {
1376                 key = options.identity_keys[i];
1377                 if (key && key->type == KEY_RSA1)
1378                         continue;
1379                 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1380                         continue;
1381                 options.identity_keys[i] = NULL;
1382                 id = xcalloc(1, sizeof(*id));
1383                 id->key = key;
1384                 id->filename = xstrdup(options.identity_files[i]);
1385                 TAILQ_INSERT_TAIL(&files, id, next);
1386         }
1387         /* list of keys supported by the agent */
1388         if ((ac = ssh_get_authentication_connection())) {
1389                 for (key = ssh_get_first_identity(ac, &comment, 2);
1390                     key != NULL;
1391                     key = ssh_get_next_identity(ac, &comment, 2)) {
1392                         found = 0;
1393                         TAILQ_FOREACH(id, &files, next) {
1394                                 /* agent keys from the config file are preferred */
1395                                 if (key_equal(key, id->key)) {
1396                                         key_free(key);
1397                                         xfree(comment);
1398                                         TAILQ_REMOVE(&files, id, next);
1399                                         TAILQ_INSERT_TAIL(preferred, id, next);
1400                                         id->ac = ac;
1401                                         found = 1;
1402                                         break;
1403                                 }
1404                         }
1405                         if (!found && !options.identities_only) {
1406                                 id = xcalloc(1, sizeof(*id));
1407                                 id->key = key;
1408                                 id->filename = comment;
1409                                 id->ac = ac;
1410                                 TAILQ_INSERT_TAIL(&agent, id, next);
1411                         }
1412                 }
1413                 /* append remaining agent keys */
1414                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1415                         TAILQ_REMOVE(&agent, id, next);
1416                         TAILQ_INSERT_TAIL(preferred, id, next);
1417                 }
1418                 authctxt->agent = ac;
1419         }
1420         /* append remaining keys from the config file */
1421         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1422                 TAILQ_REMOVE(&files, id, next);
1423                 TAILQ_INSERT_TAIL(preferred, id, next);
1424         }
1425         TAILQ_FOREACH(id, preferred, next) {
1426                 debug2("key: %s (%p)", id->filename, id->key);
1427         }
1428 }
1429
1430 static void
1431 pubkey_cleanup(Authctxt *authctxt)
1432 {
1433         Identity *id;
1434
1435         if (authctxt->agent != NULL)
1436                 ssh_close_authentication_connection(authctxt->agent);
1437         for (id = TAILQ_FIRST(&authctxt->keys); id;
1438             id = TAILQ_FIRST(&authctxt->keys)) {
1439                 TAILQ_REMOVE(&authctxt->keys, id, next);
1440                 if (id->key)
1441                         key_free(id->key);
1442                 if (id->filename)
1443                         xfree(id->filename);
1444                 xfree(id);
1445         }
1446 }
1447
1448 int
1449 userauth_pubkey(Authctxt *authctxt)
1450 {
1451         Identity *id;
1452         int sent = 0;
1453
1454         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1455                 if (id->tried++)
1456                         return (0);
1457                 /* move key to the end of the queue */
1458                 TAILQ_REMOVE(&authctxt->keys, id, next);
1459                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1460                 /*
1461                  * send a test message if we have the public key. for
1462                  * encrypted keys we cannot do this and have to load the
1463                  * private key instead
1464                  */
1465                 if (id->key && id->key->type != KEY_RSA1) {
1466                         debug("Offering %s public key: %s", key_type(id->key),
1467                             id->filename);
1468                         sent = send_pubkey_test(authctxt, id);
1469                 } else if (id->key == NULL) {
1470                         debug("Trying private key: %s", id->filename);
1471                         id->key = load_identity_file(id->filename);
1472                         if (id->key != NULL) {
1473                                 id->isprivate = 1;
1474                                 sent = sign_and_send_pubkey(authctxt, id);
1475                                 key_free(id->key);
1476                                 id->key = NULL;
1477                         }
1478                 }
1479                 if (sent)
1480                         return (sent);
1481         }
1482         return (0);
1483 }
1484
1485 /*
1486  * Send userauth request message specifying keyboard-interactive method.
1487  */
1488 int
1489 userauth_kbdint(Authctxt *authctxt)
1490 {
1491         static int attempt = 0;
1492
1493         if (attempt++ >= options.number_of_password_prompts)
1494                 return 0;
1495         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1496         if (attempt > 1 && !authctxt->info_req_seen) {
1497                 debug3("userauth_kbdint: disable: no info_req_seen");
1498                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1499                 return 0;
1500         }
1501
1502         debug2("userauth_kbdint");
1503         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1504         packet_put_cstring(authctxt->server_user);
1505         packet_put_cstring(authctxt->service);
1506         packet_put_cstring(authctxt->method->name);
1507         packet_put_cstring("");                                 /* lang */
1508         packet_put_cstring(options.kbd_interactive_devices ?
1509             options.kbd_interactive_devices : "");
1510         packet_send();
1511
1512         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1513         return 1;
1514 }
1515
1516 /*
1517  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1518  */
1519 void
1520 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1521 {
1522         Authctxt *authctxt = ctxt;
1523         char *name, *inst, *lang, *prompt, *response;
1524         u_int num_prompts, i;
1525         int echo = 0;
1526
1527         debug2("input_userauth_info_req");
1528
1529         if (authctxt == NULL)
1530                 fatal("input_userauth_info_req: no authentication context");
1531
1532         authctxt->info_req_seen = 1;
1533
1534         name = packet_get_string(NULL);
1535         inst = packet_get_string(NULL);
1536         lang = packet_get_string(NULL);
1537         if (strlen(name) > 0)
1538                 logit("%s", name);
1539         if (strlen(inst) > 0)
1540                 logit("%s", inst);
1541         xfree(name);
1542         xfree(inst);
1543         xfree(lang);
1544
1545         num_prompts = packet_get_int();
1546         /*
1547          * Begin to build info response packet based on prompts requested.
1548          * We commit to providing the correct number of responses, so if
1549          * further on we run into a problem that prevents this, we have to
1550          * be sure and clean this up and send a correct error response.
1551          */
1552         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1553         packet_put_int(num_prompts);
1554
1555         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1556         for (i = 0; i < num_prompts; i++) {
1557                 prompt = packet_get_string(NULL);
1558                 echo = packet_get_char();
1559
1560                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1561
1562                 packet_put_cstring(response);
1563                 memset(response, 0, strlen(response));
1564                 xfree(response);
1565                 xfree(prompt);
1566         }
1567         packet_check_eom(); /* done with parsing incoming message. */
1568
1569         packet_add_padding(64);
1570         packet_send();
1571 }
1572
1573 static int
1574 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1575     u_char *data, u_int datalen)
1576 {
1577         Buffer b;
1578         struct stat st;
1579         pid_t pid;
1580         int to[2], from[2], status, version = 2;
1581
1582         debug2("ssh_keysign called");
1583
1584         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1585                 error("ssh_keysign: not installed: %s", strerror(errno));
1586                 return -1;
1587         }
1588         if (fflush(stdout) != 0)
1589                 error("ssh_keysign: fflush: %s", strerror(errno));
1590         if (pipe(to) < 0) {
1591                 error("ssh_keysign: pipe: %s", strerror(errno));
1592                 return -1;
1593         }
1594         if (pipe(from) < 0) {
1595                 error("ssh_keysign: pipe: %s", strerror(errno));
1596                 return -1;
1597         }
1598         if ((pid = fork()) < 0) {
1599                 error("ssh_keysign: fork: %s", strerror(errno));
1600                 return -1;
1601         }
1602         if (pid == 0) {
1603                 /* keep the socket on exec */
1604                 fcntl(packet_get_connection_in(), F_SETFD, 0);
1605                 permanently_drop_suid(getuid());
1606                 close(from[0]);
1607                 if (dup2(from[1], STDOUT_FILENO) < 0)
1608                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1609                 close(to[1]);
1610                 if (dup2(to[0], STDIN_FILENO) < 0)
1611                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1612                 close(from[1]);
1613                 close(to[0]);
1614                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1615                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1616                     strerror(errno));
1617         }
1618         close(from[1]);
1619         close(to[0]);
1620
1621         buffer_init(&b);
1622         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1623         buffer_put_string(&b, data, datalen);
1624         if (ssh_msg_send(to[1], version, &b) == -1)
1625                 fatal("ssh_keysign: couldn't send request");
1626
1627         if (ssh_msg_recv(from[0], &b) < 0) {
1628                 error("ssh_keysign: no reply");
1629                 buffer_free(&b);
1630                 return -1;
1631         }
1632         close(from[0]);
1633         close(to[1]);
1634
1635         while (waitpid(pid, &status, 0) < 0)
1636                 if (errno != EINTR)
1637                         break;
1638
1639         if (buffer_get_char(&b) != version) {
1640                 error("ssh_keysign: bad version");
1641                 buffer_free(&b);
1642                 return -1;
1643         }
1644         *sigp = buffer_get_string(&b, lenp);
1645         buffer_free(&b);
1646
1647         return 0;
1648 }
1649
1650 int
1651 userauth_hostbased(Authctxt *authctxt)
1652 {
1653         Key *private = NULL;
1654         Sensitive *sensitive = authctxt->sensitive;
1655         Buffer b;
1656         u_char *signature, *blob;
1657         char *chost, *pkalg, *p;
1658         const char *service;
1659         u_int blen, slen;
1660         int ok, i, found = 0;
1661
1662         /* check for a useful key */
1663         for (i = 0; i < sensitive->nkeys; i++) {
1664                 private = sensitive->keys[i];
1665                 if (private && private->type != KEY_RSA1) {
1666                         found = 1;
1667                         /* we take and free the key */
1668                         sensitive->keys[i] = NULL;
1669                         break;
1670                 }
1671         }
1672         if (!found) {
1673                 debug("No more client hostkeys for hostbased authentication.");
1674                 return 0;
1675         }
1676         if (key_to_blob(private, &blob, &blen) == 0) {
1677                 key_free(private);
1678                 return 0;
1679         }
1680         /* figure out a name for the client host */
1681         p = get_local_name(packet_get_connection_in());
1682         if (p == NULL) {
1683                 error("userauth_hostbased: cannot get local ipaddr/name");
1684                 key_free(private);
1685                 xfree(blob);
1686                 return 0;
1687         }
1688         xasprintf(&chost, "%s.", p);
1689         debug2("userauth_hostbased: chost %s", chost);
1690         xfree(p);
1691
1692         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1693             authctxt->service;
1694         pkalg = xstrdup(key_ssh_name(private));
1695         buffer_init(&b);
1696         /* construct data */
1697         buffer_put_string(&b, session_id2, session_id2_len);
1698         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1699         buffer_put_cstring(&b, authctxt->server_user);
1700         buffer_put_cstring(&b, service);
1701         buffer_put_cstring(&b, authctxt->method->name);
1702         buffer_put_cstring(&b, pkalg);
1703         buffer_put_string(&b, blob, blen);
1704         buffer_put_cstring(&b, chost);
1705         buffer_put_cstring(&b, authctxt->local_user);
1706 #ifdef DEBUG_PK
1707         buffer_dump(&b);
1708 #endif
1709         if (sensitive->external_keysign)
1710                 ok = ssh_keysign(private, &signature, &slen,
1711                     buffer_ptr(&b), buffer_len(&b));
1712         else
1713                 ok = key_sign(private, &signature, &slen,
1714                     buffer_ptr(&b), buffer_len(&b));
1715         key_free(private);
1716         buffer_free(&b);
1717         if (ok != 0) {
1718                 error("key_sign failed");
1719                 xfree(chost);
1720                 xfree(pkalg);
1721                 xfree(blob);
1722                 return 0;
1723         }
1724         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1725         packet_put_cstring(authctxt->server_user);
1726         packet_put_cstring(authctxt->service);
1727         packet_put_cstring(authctxt->method->name);
1728         packet_put_cstring(pkalg);
1729         packet_put_string(blob, blen);
1730         packet_put_cstring(chost);
1731         packet_put_cstring(authctxt->local_user);
1732         packet_put_string(signature, slen);
1733         memset(signature, 's', slen);
1734         xfree(signature);
1735         xfree(chost);
1736         xfree(pkalg);
1737         xfree(blob);
1738
1739         packet_send();
1740         return 1;
1741 }
1742
1743 #ifdef JPAKE
1744 int
1745 userauth_jpake(Authctxt *authctxt)
1746 {
1747         struct jpake_ctx *pctx;
1748         u_char *x1_proof, *x2_proof;
1749         u_int x1_proof_len, x2_proof_len;
1750         static int attempt = 0; /* XXX share with userauth_password's? */
1751
1752         if (attempt++ >= options.number_of_password_prompts)
1753                 return 0;
1754         if (attempt != 1)
1755                 error("Permission denied, please try again.");
1756
1757         if (authctxt->methoddata != NULL)
1758                 fatal("%s: authctxt->methoddata already set (%p)",
1759                     __func__, authctxt->methoddata);
1760
1761         authctxt->methoddata = pctx = jpake_new();
1762
1763         /*
1764          * Send request immediately, to get the protocol going while
1765          * we do the initial computations.
1766          */
1767         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1768         packet_put_cstring(authctxt->server_user);
1769         packet_put_cstring(authctxt->service);
1770         packet_put_cstring(authctxt->method->name);
1771         packet_send();
1772         packet_write_wait();
1773
1774         jpake_step1(pctx->grp,
1775             &pctx->client_id, &pctx->client_id_len,
1776             &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2,
1777             &x1_proof, &x1_proof_len,
1778             &x2_proof, &x2_proof_len);
1779
1780         JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__));
1781
1782         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1);
1783         packet_put_string(pctx->client_id, pctx->client_id_len);
1784         packet_put_bignum2(pctx->g_x1);
1785         packet_put_bignum2(pctx->g_x2);
1786         packet_put_string(x1_proof, x1_proof_len);
1787         packet_put_string(x2_proof, x2_proof_len);
1788         packet_send();
1789
1790         bzero(x1_proof, x1_proof_len);
1791         bzero(x2_proof, x2_proof_len);
1792         xfree(x1_proof);
1793         xfree(x2_proof);
1794
1795         /* Expect step 1 packet from peer */
1796         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1,
1797             input_userauth_jpake_server_step1);
1798         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS,
1799             &input_userauth_success_unexpected);
1800
1801         return 1;
1802 }
1803
1804 void
1805 userauth_jpake_cleanup(Authctxt *authctxt)
1806 {
1807         debug3("%s: clean up", __func__);
1808         if (authctxt->methoddata != NULL) {
1809                 jpake_free(authctxt->methoddata);
1810                 authctxt->methoddata = NULL;
1811         }
1812         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
1813 }
1814 #endif /* JPAKE */
1815
1816 /* find auth method */
1817
1818 /*
1819  * given auth method name, if configurable options permit this method fill
1820  * in auth_ident field and return true, otherwise return false.
1821  */
1822 static int
1823 authmethod_is_enabled(Authmethod *method)
1824 {
1825         if (method == NULL)
1826                 return 0;
1827         /* return false if options indicate this method is disabled */
1828         if  (method->enabled == NULL || *method->enabled == 0)
1829                 return 0;
1830         /* return false if batch mode is enabled but method needs interactive mode */
1831         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1832                 return 0;
1833         return 1;
1834 }
1835
1836 static Authmethod *
1837 authmethod_lookup(const char *name)
1838 {
1839         Authmethod *method = NULL;
1840         if (name != NULL)
1841                 for (method = authmethods; method->name != NULL; method++)
1842                         if (strcmp(name, method->name) == 0)
1843                                 return method;
1844         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1845         return NULL;
1846 }
1847
1848 /* XXX internal state */
1849 static Authmethod *current = NULL;
1850 static char *supported = NULL;
1851 static char *preferred = NULL;
1852
1853 /*
1854  * Given the authentication method list sent by the server, return the
1855  * next method we should try.  If the server initially sends a nil list,
1856  * use a built-in default list.
1857  */
1858 static Authmethod *
1859 authmethod_get(char *authlist)
1860 {
1861         char *name = NULL;
1862         u_int next;
1863
1864         /* Use a suitable default if we're passed a nil list.  */
1865         if (authlist == NULL || strlen(authlist) == 0)
1866                 authlist = options.preferred_authentications;
1867
1868         if (supported == NULL || strcmp(authlist, supported) != 0) {
1869                 debug3("start over, passed a different list %s", authlist);
1870                 if (supported != NULL)
1871                         xfree(supported);
1872                 supported = xstrdup(authlist);
1873                 preferred = options.preferred_authentications;
1874                 debug3("preferred %s", preferred);
1875                 current = NULL;
1876         } else if (current != NULL && authmethod_is_enabled(current))
1877                 return current;
1878
1879         for (;;) {
1880                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1881                         debug("No more authentication methods to try.");
1882                         current = NULL;
1883                         return NULL;
1884                 }
1885                 preferred += next;
1886                 debug3("authmethod_lookup %s", name);
1887                 debug3("remaining preferred: %s", preferred);
1888                 if ((current = authmethod_lookup(name)) != NULL &&
1889                     authmethod_is_enabled(current)) {
1890                         debug3("authmethod_is_enabled %s", name);
1891                         debug("Next authentication method: %s", name);
1892                         xfree(name);
1893                         return current;
1894                 }
1895         }
1896         if (name != NULL)
1897                 xfree(name);
1898 }
1899
1900 static char *
1901 authmethods_get(void)
1902 {
1903         Authmethod *method = NULL;
1904         Buffer b;
1905         char *list;
1906
1907         buffer_init(&b);
1908         for (method = authmethods; method->name != NULL; method++) {
1909                 if (authmethod_is_enabled(method)) {
1910                         if (buffer_len(&b) > 0)
1911                                 buffer_append(&b, ",", 1);
1912                         buffer_append(&b, method->name, strlen(method->name));
1913                 }
1914         }
1915         buffer_append(&b, "\0", 1);
1916         list = xstrdup(buffer_ptr(&b));
1917         buffer_free(&b);
1918         return list;
1919 }
1920