crypto/openssh/sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.204 2014/02/02 03:44:32 djm Exp $ */
   2 /* $FreeBSD$ */
   3 /*
   4  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   5  * Copyright (c) 2008 Damien Miller.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 #include "includes.h"
  29
  30 #include <sys/types.h>
  31 #include <sys/socket.h>
  32 #include <sys/wait.h>
  33 #include <sys/stat.h>
  34
  35 #include <errno.h>
  36 #include <fcntl.h>
  37 #include <netdb.h>
  38 #include <pwd.h>
  39 #include <signal.h>
  40 #include <stdarg.h>
  41 #include <stdio.h>
  42 #include <string.h>
  43 #include <unistd.h>
  44 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS)
  45 #include <vis.h>
  46 #endif
  47
  48 #include "openbsd-compat/sys-queue.h"
  49
  50 #include "xmalloc.h"
  51 #include "ssh.h"
  52 #include "ssh2.h"
  53 #include "buffer.h"
  54 #include "packet.h"
  55 #include "compat.h"
  56 #include "cipher.h"
  57 #include "key.h"
  58 #include "kex.h"
  59 #include "myproposal.h"
  60 #include "sshconnect.h"
  61 #include "authfile.h"
  62 #include "dh.h"
  63 #include "authfd.h"
  64 #include "log.h"
  65 #include "readconf.h"
  66 #include "misc.h"
  67 #include "match.h"
  68 #include "dispatch.h"
  69 #include "canohost.h"
  70 #include "msg.h"
  71 #include "pathnames.h"
  72 #include "uidswap.h"
  73 #include "hostfile.h"
  74
  75 #ifdef GSSAPI
  76 #include "ssh-gss.h"
  77 #endif
  78
  79 /* import */
  80 extern char *client_version_string;
  81 extern char *server_version_string;
  82 extern Options options;
  83 #ifdef  NONE_CIPHER_ENABLED
  84 extern Kex *xxx_kex;
  85
  86 /*
  87  * tty_flag is set in ssh.c so we can use it here.  If set then prevent
  88  * the switch to the null cipher.
  89  */
  90
  91 extern int tty_flag;
  92 #endif
  93
  94 /*
  95  * SSH2 key exchange
  96  */
  97
  98 u_char *session_id2 = NULL;
  99 u_int session_id2_len = 0;
 100
 101 char *xxx_host;
 102 struct sockaddr *xxx_hostaddr;
 103
 104 Kex *xxx_kex = NULL;
 105
 106 static int
 107 verify_host_key_callback(Key *hostkey)
 108 {
 109         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
 110                 fatal("Host key verification failed.");
 111         return 0;
 112 }
 113
 114 static char *
 115 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
 116 {
 117         char *oavail, *avail, *first, *last, *alg, *hostname, *ret;
 118         size_t maxlen;
 119         struct hostkeys *hostkeys;
 120         int ktype;
 121         u_int i;
 122
 123         /* Find all hostkeys for this hostname */
 124         get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
 125         hostkeys = init_hostkeys();
 126         for (i = 0; i < options.num_user_hostfiles; i++)
 127                 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]);
 128         for (i = 0; i < options.num_system_hostfiles; i++)
 129                 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]);
 130
 131         oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG);
 132         maxlen = strlen(avail) + 1;
 133         first = xmalloc(maxlen);
 134         last = xmalloc(maxlen);
 135         *first = *last = '\0';
 136
 137 #define ALG_APPEND(to, from) \
 138         do { \
 139                 if (*to != '\0') \
 140                         strlcat(to, ",", maxlen); \
 141                 strlcat(to, from, maxlen); \
 142         } while (0)
 143
 144         while ((alg = strsep(&avail, ",")) && *alg != '\0') {
 145                 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC)
 146                         fatal("%s: unknown alg %s", __func__, alg);
 147                 if (lookup_key_in_hostkeys_by_type(hostkeys,
 148                     key_type_plain(ktype), NULL))
 149                         ALG_APPEND(first, alg);
 150                 else
 151                         ALG_APPEND(last, alg);
 152         }
 153 #undef ALG_APPEND
 154         xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last);
 155         if (*first != '\0')
 156                 debug3("%s: prefer hostkeyalgs: %s", __func__, first);
 157
 158         free(first);
 159         free(last);
 160         free(hostname);
 161         free(oavail);
 162         free_hostkeys(hostkeys);
 163
 164         return ret;
 165 }
 166
 167 void
 168 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
 169 {
 170         Kex *kex;
 171
 172         xxx_host = host;
 173         xxx_hostaddr = hostaddr;
 174
 175         if (options.ciphers == (char *)-1) {
 176                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 177                 options.ciphers = NULL;
 178         }
 179         if (options.ciphers != NULL) {
 180                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 181                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 182         }
 183         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 184             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 185         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 186             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 187         if (options.compression) {
 188                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 189                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 190         } else {
 191                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 192                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 193         }
 194         if (options.macs != NULL) {
 195                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 196                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 197         }
 198         if (options.hostkeyalgorithms != NULL)
 199                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 200                     compat_pkalg_proposal(options.hostkeyalgorithms);
 201         else {
 202                 /* Prefer algorithms that we already have keys for */
 203                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 204                     compat_pkalg_proposal(
 205                     order_hostkeyalgs(host, hostaddr, port));
 206         }
 207         if (options.kex_algorithms != NULL)
 208                 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
 209
 210         if (options.rekey_limit || options.rekey_interval)
 211                 packet_set_rekey_limits((u_int32_t)options.rekey_limit,
 212                     (time_t)options.rekey_interval);
 213
 214         /* start key exchange */
 215         kex = kex_setup(myproposal);
 216         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 217         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 218         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 219         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 220         kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
 221         kex->kex[KEX_C25519_SHA256] = kexc25519_client;
 222         kex->client_version_string=client_version_string;
 223         kex->server_version_string=server_version_string;
 224         kex->verify_host_key=&verify_host_key_callback;
 225
 226         xxx_kex = kex;
 227
 228         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 229
 230         if (options.use_roaming && !kex->roaming) {
 231                 debug("Roaming not allowed by server");
 232                 options.use_roaming = 0;
 233         }
 234
 235         session_id2 = kex->session_id;
 236         session_id2_len = kex->session_id_len;
 237
 238 #ifdef DEBUG_KEXDH
 239         /* send 1st encrypted/maced/compressed message */
 240         packet_start(SSH2_MSG_IGNORE);
 241         packet_put_cstring("markus");
 242         packet_send();
 243         packet_write_wait();
 244 #endif
 245 }
 246
 247 /*
 248  * Authenticate user
 249  */
 250
 251 typedef struct Authctxt Authctxt;
 252 typedef struct Authmethod Authmethod;
 253 typedef struct identity Identity;
 254 typedef struct idlist Idlist;
 255
 256 struct identity {
 257         TAILQ_ENTRY(identity) next;
 258         AuthenticationConnection *ac;   /* set if agent supports key */
 259         Key     *key;                   /* public/private key */
 260         char    *filename;              /* comment for agent-only keys */
 261         int     tried;
 262         int     isprivate;              /* key points to the private key */
 263         int     userprovided;
 264 };
 265 TAILQ_HEAD(idlist, identity);
 266
 267 struct Authctxt {
 268         const char *server_user;
 269         const char *local_user;
 270         const char *host;
 271         const char *service;
 272         Authmethod *method;
 273         sig_atomic_t success;
 274         char *authlist;
 275         /* pubkey */
 276         Idlist keys;
 277         AuthenticationConnection *agent;
 278         /* hostbased */
 279         Sensitive *sensitive;
 280         /* kbd-interactive */
 281         int info_req_seen;
 282         /* generic */
 283         void *methoddata;
 284 };
 285 struct Authmethod {
 286         char    *name;          /* string to compare against server's list */
 287         int     (*userauth)(Authctxt *authctxt);
 288         void    (*cleanup)(Authctxt *authctxt);
 289         int     *enabled;       /* flag in option struct that enables method */
 290         int     *batch_flag;    /* flag in option struct that disables method */
 291 };
 292
 293 void    input_userauth_success(int, u_int32_t, void *);
 294 void    input_userauth_success_unexpected(int, u_int32_t, void *);
 295 void    input_userauth_failure(int, u_int32_t, void *);
 296 void    input_userauth_banner(int, u_int32_t, void *);
 297 void    input_userauth_error(int, u_int32_t, void *);
 298 void    input_userauth_info_req(int, u_int32_t, void *);
 299 void    input_userauth_pk_ok(int, u_int32_t, void *);
 300 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 301
 302 int     userauth_none(Authctxt *);
 303 int     userauth_pubkey(Authctxt *);
 304 int     userauth_passwd(Authctxt *);
 305 int     userauth_kbdint(Authctxt *);
 306 int     userauth_hostbased(Authctxt *);
 307
 308 #ifdef GSSAPI
 309 int     userauth_gssapi(Authctxt *authctxt);
 310 void    input_gssapi_response(int type, u_int32_t, void *);
 311 void    input_gssapi_token(int type, u_int32_t, void *);
 312 void    input_gssapi_hash(int type, u_int32_t, void *);
 313 void    input_gssapi_error(int, u_int32_t, void *);
 314 void    input_gssapi_errtok(int, u_int32_t, void *);
 315 #endif
 316
 317 void    userauth(Authctxt *, char *);
 318
 319 static int sign_and_send_pubkey(Authctxt *, Identity *);
 320 static void pubkey_prepare(Authctxt *);
 321 static void pubkey_cleanup(Authctxt *);
 322 static Key *load_identity_file(char *, int);
 323
 324 static Authmethod *authmethod_get(char *authlist);
 325 static Authmethod *authmethod_lookup(const char *name);
 326 static char *authmethods_get(void);
 327
 328 Authmethod authmethods[] = {
 329 #ifdef GSSAPI
 330         {"gssapi-with-mic",
 331                 userauth_gssapi,
 332                 NULL,
 333                 &options.gss_authentication,
 334                 NULL},
 335 #endif
 336         {"hostbased",
 337                 userauth_hostbased,
 338                 NULL,
 339                 &options.hostbased_authentication,
 340                 NULL},
 341         {"publickey",
 342                 userauth_pubkey,
 343                 NULL,
 344                 &options.pubkey_authentication,
 345                 NULL},
 346         {"keyboard-interactive",
 347                 userauth_kbdint,
 348                 NULL,
 349                 &options.kbd_interactive_authentication,
 350                 &options.batch_mode},
 351         {"password",
 352                 userauth_passwd,
 353                 NULL,
 354                 &options.password_authentication,
 355                 &options.batch_mode},
 356         {"none",
 357                 userauth_none,
 358                 NULL,
 359                 NULL,
 360                 NULL},
 361         {NULL, NULL, NULL, NULL, NULL}
 362 };
 363
 364 void
 365 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 366     Sensitive *sensitive)
 367 {
 368         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                 free(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 #ifdef  NONE_CIPHER_ENABLED
 424         /*
 425          * If the user explicitly requests to use the none cipher enable it
 426          * post authentication and only if the right conditions are met: both
 427          * of the NONE switches must be true and there must be no tty allocated.
 428          */
 429         if (options.none_switch == 1 && options.none_enabled == 1) {
 430                 if (!tty_flag) {
 431                         debug("Requesting none cipher re-keying...");
 432                         myproposal[PROPOSAL_ENC_ALGS_STOC] = "none";
 433                         myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none";
 434                         kex_prop2buf(&xxx_kex->my, myproposal);
 435                         packet_request_rekeying();
 436                         fprintf(stderr, "WARNING: enabled NONE cipher\n");
 437                 } else {
 438                         /* Requested NONE cipher on an interactive session. */
 439                         debug("Cannot switch to NONE cipher with tty "
 440                             "allocated");
 441                         fprintf(stderr, "NONE cipher switch disabled given "
 442                             "a TTY is allocated\n");
 443                 }
 444         }
 445 #endif
 446         debug("Authentication succeeded (%s).", authctxt.method->name);
 447 }
 448
 449 void
 450 userauth(Authctxt *authctxt, char *authlist)
 451 {
 452         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 453                 authctxt->method->cleanup(authctxt);
 454
 455         free(authctxt->methoddata);
 456         authctxt->methoddata = NULL;
 457         if (authlist == NULL) {
 458                 authlist = authctxt->authlist;
 459         } else {
 460                 free(authctxt->authlist);
 461                 authctxt->authlist = authlist;
 462         }
 463         for (;;) {
 464                 Authmethod *method = authmethod_get(authlist);
 465                 if (method == NULL)
 466                         fatal("Permission denied (%s).", authlist);
 467                 authctxt->method = method;
 468
 469                 /* reset the per method handler */
 470                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 471                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 472
 473                 /* and try new method */
 474                 if (method->userauth(authctxt) != 0) {
 475                         debug2("we sent a %s packet, wait for reply", method->name);
 476                         break;
 477                 } else {
 478                         debug2("we did not send a packet, disable method");
 479                         method->enabled = NULL;
 480                 }
 481         }
 482 }
 483
 484 /* ARGSUSED */
 485 void
 486 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 487 {
 488         fatal("input_userauth_error: bad message during authentication: "
 489             "type %d", type);
 490 }
 491
 492 /* ARGSUSED */
 493 void
 494 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 495 {
 496         char *msg, *raw, *lang;
 497         u_int len;
 498
 499         debug3("input_userauth_banner");
 500         raw = packet_get_string(&len);
 501         lang = packet_get_string(NULL);
 502         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
 503                 if (len > 65536)
 504                         len = 65536;
 505                 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
 506                 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH);
 507                 fprintf(stderr, "%s", msg);
 508                 free(msg);
 509         }
 510         free(raw);
 511         free(lang);
 512 }
 513
 514 /* ARGSUSED */
 515 void
 516 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 517 {
 518         Authctxt *authctxt = ctxt;
 519
 520         if (authctxt == NULL)
 521                 fatal("input_userauth_success: no authentication context");
 522         free(authctxt->authlist);
 523         authctxt->authlist = NULL;
 524         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 525                 authctxt->method->cleanup(authctxt);
 526         free(authctxt->methoddata);
 527         authctxt->methoddata = NULL;
 528         authctxt->success = 1;                  /* break out */
 529 }
 530
 531 void
 532 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
 533 {
 534         Authctxt *authctxt = ctxt;
 535
 536         if (authctxt == NULL)
 537                 fatal("%s: no authentication context", __func__);
 538
 539         fatal("Unexpected authentication success during %s.",
 540             authctxt->method->name);
 541 }
 542
 543 /* ARGSUSED */
 544 void
 545 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 546 {
 547         Authctxt *authctxt = ctxt;
 548         char *authlist = NULL;
 549         int partial;
 550
 551         if (authctxt == NULL)
 552                 fatal("input_userauth_failure: no authentication context");
 553
 554         authlist = packet_get_string(NULL);
 555         partial = packet_get_char();
 556         packet_check_eom();
 557
 558         if (partial != 0) {
 559                 logit("Authenticated with partial success.");
 560                 /* reset state */
 561                 pubkey_cleanup(authctxt);
 562                 pubkey_prepare(authctxt);
 563         }
 564         debug("Authentications that can continue: %s", authlist);
 565
 566         userauth(authctxt, authlist);
 567 }
 568
 569 /* ARGSUSED */
 570 void
 571 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 572 {
 573         Authctxt *authctxt = ctxt;
 574         Key *key = NULL;
 575         Identity *id = NULL;
 576         Buffer b;
 577         int pktype, sent = 0;
 578         u_int alen, blen;
 579         char *pkalg, *fp;
 580         u_char *pkblob;
 581
 582         if (authctxt == NULL)
 583                 fatal("input_userauth_pk_ok: no authentication context");
 584         if (datafellows & SSH_BUG_PKOK) {
 585                 /* this is similar to SSH_BUG_PKAUTH */
 586                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 587                 pkblob = packet_get_string(&blen);
 588                 buffer_init(&b);
 589                 buffer_append(&b, pkblob, blen);
 590                 pkalg = buffer_get_string(&b, &alen);
 591                 buffer_free(&b);
 592         } else {
 593                 pkalg = packet_get_string(&alen);
 594                 pkblob = packet_get_string(&blen);
 595         }
 596         packet_check_eom();
 597
 598         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 599
 600         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 601                 debug("unknown pkalg %s", pkalg);
 602                 goto done;
 603         }
 604         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 605                 debug("no key from blob. pkalg %s", pkalg);
 606                 goto done;
 607         }
 608         if (key->type != pktype) {
 609                 error("input_userauth_pk_ok: type mismatch "
 610                     "for decoded key (received %d, expected %d)",
 611                     key->type, pktype);
 612                 goto done;
 613         }
 614         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 615         debug2("input_userauth_pk_ok: fp %s", fp);
 616         free(fp);
 617
 618         /*
 619          * search keys in the reverse order, because last candidate has been
 620          * moved to the end of the queue.  this also avoids confusion by
 621          * duplicate keys
 622          */
 623         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 624                 if (key_equal(key, id->key)) {
 625                         sent = sign_and_send_pubkey(authctxt, id);
 626                         break;
 627                 }
 628         }
 629 done:
 630         if (key != NULL)
 631                 key_free(key);
 632         free(pkalg);
 633         free(pkblob);
 634
 635         /* try another method if we did not send a packet */
 636         if (sent == 0)
 637                 userauth(authctxt, NULL);
 638 }
 639
 640 #ifdef GSSAPI
 641 int
 642 userauth_gssapi(Authctxt *authctxt)
 643 {
 644         Gssctxt *gssctxt = NULL;
 645         static gss_OID_set gss_supported = NULL;
 646         static u_int mech = 0;
 647         OM_uint32 min;
 648         int ok = 0;
 649
 650         /* Try one GSSAPI method at a time, rather than sending them all at
 651          * once. */
 652
 653         if (gss_supported == NULL)
 654                 gss_indicate_mechs(&min, &gss_supported);
 655
 656         /* Check to see if the mechanism is usable before we offer it */
 657         while (mech < gss_supported->count && !ok) {
 658                 /* My DER encoding requires length<128 */
 659                 if (gss_supported->elements[mech].length < 128 &&
 660                     ssh_gssapi_check_mechanism(&gssctxt,
 661                     &gss_supported->elements[mech], authctxt->host)) {
 662                         ok = 1; /* Mechanism works */
 663                 } else {
 664                         mech++;
 665                 }
 666         }
 667
 668         if (!ok)
 669                 return 0;
 670
 671         authctxt->methoddata=(void *)gssctxt;
 672
 673         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 674         packet_put_cstring(authctxt->server_user);
 675         packet_put_cstring(authctxt->service);
 676         packet_put_cstring(authctxt->method->name);
 677
 678         packet_put_int(1);
 679
 680         packet_put_int((gss_supported->elements[mech].length) + 2);
 681         packet_put_char(SSH_GSS_OIDTYPE);
 682         packet_put_char(gss_supported->elements[mech].length);
 683         packet_put_raw(gss_supported->elements[mech].elements,
 684             gss_supported->elements[mech].length);
 685
 686         packet_send();
 687
 688         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 689         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 690         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 691         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 692
 693         mech++; /* Move along to next candidate */
 694
 695         return 1;
 696 }
 697
 698 static OM_uint32
 699 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 700 {
 701         Authctxt *authctxt = ctxt;
 702         Gssctxt *gssctxt = authctxt->methoddata;
 703         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 704         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 705         gss_buffer_desc gssbuf;
 706         OM_uint32 status, ms, flags;
 707         Buffer b;
 708
 709         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 710             recv_tok, &send_tok, &flags);
 711
 712         if (send_tok.length > 0) {
 713                 if (GSS_ERROR(status))
 714                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 715                 else
 716                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 717
 718                 packet_put_string(send_tok.value, send_tok.length);
 719                 packet_send();
 720                 gss_release_buffer(&ms, &send_tok);
 721         }
 722
 723         if (status == GSS_S_COMPLETE) {
 724                 /* send either complete or MIC, depending on mechanism */
 725                 if (!(flags & GSS_C_INTEG_FLAG)) {
 726                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 727                         packet_send();
 728                 } else {
 729                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 730                             authctxt->service, "gssapi-with-mic");
 731
 732                         gssbuf.value = buffer_ptr(&b);
 733                         gssbuf.length = buffer_len(&b);
 734
 735                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 736
 737                         if (!GSS_ERROR(status)) {
 738                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 739                                 packet_put_string(mic.value, mic.length);
 740
 741                                 packet_send();
 742                         }
 743
 744                         buffer_free(&b);
 745                         gss_release_buffer(&ms, &mic);
 746                 }
 747         }
 748
 749         return status;
 750 }
 751
 752 /* ARGSUSED */
 753 void
 754 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 755 {
 756         Authctxt *authctxt = ctxt;
 757         Gssctxt *gssctxt;
 758         int oidlen;
 759         char *oidv;
 760
 761         if (authctxt == NULL)
 762                 fatal("input_gssapi_response: no authentication context");
 763         gssctxt = authctxt->methoddata;
 764
 765         /* Setup our OID */
 766         oidv = packet_get_string(&oidlen);
 767
 768         if (oidlen <= 2 ||
 769             oidv[0] != SSH_GSS_OIDTYPE ||
 770             oidv[1] != oidlen - 2) {
 771                 free(oidv);
 772                 debug("Badly encoded mechanism OID received");
 773                 userauth(authctxt, NULL);
 774                 return;
 775         }
 776
 777         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 778                 fatal("Server returned different OID than expected");
 779
 780         packet_check_eom();
 781
 782         free(oidv);
 783
 784         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 785                 /* Start again with next method on list */
 786                 debug("Trying to start again");
 787                 userauth(authctxt, NULL);
 788                 return;
 789         }
 790 }
 791
 792 /* ARGSUSED */
 793 void
 794 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 795 {
 796         Authctxt *authctxt = ctxt;
 797         gss_buffer_desc recv_tok;
 798         OM_uint32 status;
 799         u_int slen;
 800
 801         if (authctxt == NULL)
 802                 fatal("input_gssapi_response: no authentication context");
 803
 804         recv_tok.value = packet_get_string(&slen);
 805         recv_tok.length = slen; /* safe typecast */
 806
 807         packet_check_eom();
 808
 809         status = process_gssapi_token(ctxt, &recv_tok);
 810
 811         free(recv_tok.value);
 812
 813         if (GSS_ERROR(status)) {
 814                 /* Start again with the next method in the list */
 815                 userauth(authctxt, NULL);
 816                 return;
 817         }
 818 }
 819
 820 /* ARGSUSED */
 821 void
 822 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 823 {
 824         Authctxt *authctxt = ctxt;
 825         Gssctxt *gssctxt;
 826         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 827         gss_buffer_desc recv_tok;
 828         OM_uint32 ms;
 829         u_int len;
 830
 831         if (authctxt == NULL)
 832                 fatal("input_gssapi_response: no authentication context");
 833         gssctxt = authctxt->methoddata;
 834
 835         recv_tok.value = packet_get_string(&len);
 836         recv_tok.length = len;
 837
 838         packet_check_eom();
 839
 840         /* Stick it into GSSAPI and see what it says */
 841         (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 842             &recv_tok, &send_tok, NULL);
 843
 844         free(recv_tok.value);
 845         gss_release_buffer(&ms, &send_tok);
 846
 847         /* Server will be returning a failed packet after this one */
 848 }
 849
 850 /* ARGSUSED */
 851 void
 852 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 853 {
 854         char *msg;
 855         char *lang;
 856
 857         /* maj */(void)packet_get_int();
 858         /* min */(void)packet_get_int();
 859         msg=packet_get_string(NULL);
 860         lang=packet_get_string(NULL);
 861
 862         packet_check_eom();
 863
 864         debug("Server GSSAPI Error:\n%s", msg);
 865         free(msg);
 866         free(lang);
 867 }
 868 #endif /* GSSAPI */
 869
 870 int
 871 userauth_none(Authctxt *authctxt)
 872 {
 873         /* initial userauth request */
 874         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 875         packet_put_cstring(authctxt->server_user);
 876         packet_put_cstring(authctxt->service);
 877         packet_put_cstring(authctxt->method->name);
 878         packet_send();
 879         return 1;
 880 }
 881
 882 int
 883 userauth_passwd(Authctxt *authctxt)
 884 {
 885         static int attempt = 0;
 886         char prompt[150];
 887         char *password;
 888         const char *host = options.host_key_alias ?  options.host_key_alias :
 889             authctxt->host;
 890
 891         if (attempt++ >= options.number_of_password_prompts)
 892                 return 0;
 893
 894         if (attempt != 1)
 895                 error("Permission denied, please try again.");
 896
 897         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 898             authctxt->server_user, host);
 899         password = read_passphrase(prompt, 0);
 900         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 901         packet_put_cstring(authctxt->server_user);
 902         packet_put_cstring(authctxt->service);
 903         packet_put_cstring(authctxt->method->name);
 904         packet_put_char(0);
 905         packet_put_cstring(password);
 906         explicit_bzero(password, strlen(password));
 907         free(password);
 908         packet_add_padding(64);
 909         packet_send();
 910
 911         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 912             &input_userauth_passwd_changereq);
 913
 914         return 1;
 915 }
 916
 917 /*
 918  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 919  */
 920 /* ARGSUSED */
 921 void
 922 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 923 {
 924         Authctxt *authctxt = ctxt;
 925         char *info, *lang, *password = NULL, *retype = NULL;
 926         char prompt[150];
 927         const char *host = options.host_key_alias ? options.host_key_alias :
 928             authctxt->host;
 929
 930         debug2("input_userauth_passwd_changereq");
 931
 932         if (authctxt == NULL)
 933                 fatal("input_userauth_passwd_changereq: "
 934                     "no authentication context");
 935
 936         info = packet_get_string(NULL);
 937         lang = packet_get_string(NULL);
 938         if (strlen(info) > 0)
 939                 logit("%s", info);
 940         free(info);
 941         free(lang);
 942         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 943         packet_put_cstring(authctxt->server_user);
 944         packet_put_cstring(authctxt->service);
 945         packet_put_cstring(authctxt->method->name);
 946         packet_put_char(1);                     /* additional info */
 947         snprintf(prompt, sizeof(prompt),
 948             "Enter %.30s@%.128s's old password: ",
 949             authctxt->server_user, host);
 950         password = read_passphrase(prompt, 0);
 951         packet_put_cstring(password);
 952         explicit_bzero(password, strlen(password));
 953         free(password);
 954         password = NULL;
 955         while (password == NULL) {
 956                 snprintf(prompt, sizeof(prompt),
 957                     "Enter %.30s@%.128s's new password: ",
 958                     authctxt->server_user, host);
 959                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 960                 if (password == NULL) {
 961                         /* bail out */
 962                         return;
 963                 }
 964                 snprintf(prompt, sizeof(prompt),
 965                     "Retype %.30s@%.128s's new password: ",
 966                     authctxt->server_user, host);
 967                 retype = read_passphrase(prompt, 0);
 968                 if (strcmp(password, retype) != 0) {
 969                         explicit_bzero(password, strlen(password));
 970                         free(password);
 971                         logit("Mismatch; try again, EOF to quit.");
 972                         password = NULL;
 973                 }
 974                 explicit_bzero(retype, strlen(retype));
 975                 free(retype);
 976         }
 977         packet_put_cstring(password);
 978         explicit_bzero(password, strlen(password));
 979         free(password);
 980         packet_add_padding(64);
 981         packet_send();
 982
 983         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 984             &input_userauth_passwd_changereq);
 985 }
 986
 987 static int
 988 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
 989     u_char *data, u_int datalen)
 990 {
 991         Key *prv;
 992         int ret;
 993
 994         /* the agent supports this key */
 995         if (id->ac)
 996                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
 997                     data, datalen));
 998         /*
 999          * we have already loaded the private key or
1000          * the private key is stored in external hardware
1001          */
1002         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1003                 return (key_sign(id->key, sigp, lenp, data, datalen));
1004         /* load the private key from the file */
1005         if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL)
1006                 return (-1);
1007         ret = key_sign(prv, sigp, lenp, data, datalen);
1008         key_free(prv);
1009         return (ret);
1010 }
1011
1012 static int
1013 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1014 {
1015         Buffer b;
1016         u_char *blob, *signature;
1017         u_int bloblen, slen;
1018         u_int skip = 0;
1019         int ret = -1;
1020         int have_sig = 1;
1021         char *fp;
1022
1023         fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
1024         debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp);
1025         free(fp);
1026
1027         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1028                 /* we cannot handle this key */
1029                 debug3("sign_and_send_pubkey: cannot handle key");
1030                 return 0;
1031         }
1032         /* data to be signed */
1033         buffer_init(&b);
1034         if (datafellows & SSH_OLD_SESSIONID) {
1035                 buffer_append(&b, session_id2, session_id2_len);
1036                 skip = session_id2_len;
1037         } else {
1038                 buffer_put_string(&b, session_id2, session_id2_len);
1039                 skip = buffer_len(&b);
1040         }
1041         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1042         buffer_put_cstring(&b, authctxt->server_user);
1043         buffer_put_cstring(&b,
1044             datafellows & SSH_BUG_PKSERVICE ?
1045             "ssh-userauth" :
1046             authctxt->service);
1047         if (datafellows & SSH_BUG_PKAUTH) {
1048                 buffer_put_char(&b, have_sig);
1049         } else {
1050                 buffer_put_cstring(&b, authctxt->method->name);
1051                 buffer_put_char(&b, have_sig);
1052                 buffer_put_cstring(&b, key_ssh_name(id->key));
1053         }
1054         buffer_put_string(&b, blob, bloblen);
1055
1056         /* generate signature */
1057         ret = identity_sign(id, &signature, &slen,
1058             buffer_ptr(&b), buffer_len(&b));
1059         if (ret == -1) {
1060                 free(blob);
1061                 buffer_free(&b);
1062                 return 0;
1063         }
1064 #ifdef DEBUG_PK
1065         buffer_dump(&b);
1066 #endif
1067         if (datafellows & SSH_BUG_PKSERVICE) {
1068                 buffer_clear(&b);
1069                 buffer_append(&b, session_id2, session_id2_len);
1070                 skip = session_id2_len;
1071                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1072                 buffer_put_cstring(&b, authctxt->server_user);
1073                 buffer_put_cstring(&b, authctxt->service);
1074                 buffer_put_cstring(&b, authctxt->method->name);
1075                 buffer_put_char(&b, have_sig);
1076                 if (!(datafellows & SSH_BUG_PKAUTH))
1077                         buffer_put_cstring(&b, key_ssh_name(id->key));
1078                 buffer_put_string(&b, blob, bloblen);
1079         }
1080         free(blob);
1081
1082         /* append signature */
1083         buffer_put_string(&b, signature, slen);
1084         free(signature);
1085
1086         /* skip session id and packet type */
1087         if (buffer_len(&b) < skip + 1)
1088                 fatal("userauth_pubkey: internal error");
1089         buffer_consume(&b, skip + 1);
1090
1091         /* put remaining data from buffer into packet */
1092         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1093         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1094         buffer_free(&b);
1095         packet_send();
1096
1097         return 1;
1098 }
1099
1100 static int
1101 send_pubkey_test(Authctxt *authctxt, Identity *id)
1102 {
1103         u_char *blob;
1104         u_int bloblen, have_sig = 0;
1105
1106         debug3("send_pubkey_test");
1107
1108         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1109                 /* we cannot handle this key */
1110                 debug3("send_pubkey_test: cannot handle key");
1111                 return 0;
1112         }
1113         /* register callback for USERAUTH_PK_OK message */
1114         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1115
1116         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1117         packet_put_cstring(authctxt->server_user);
1118         packet_put_cstring(authctxt->service);
1119         packet_put_cstring(authctxt->method->name);
1120         packet_put_char(have_sig);
1121         if (!(datafellows & SSH_BUG_PKAUTH))
1122                 packet_put_cstring(key_ssh_name(id->key));
1123         packet_put_string(blob, bloblen);
1124         free(blob);
1125         packet_send();
1126         return 1;
1127 }
1128
1129 static Key *
1130 load_identity_file(char *filename, int userprovided)
1131 {
1132         Key *private;
1133         char prompt[300], *passphrase;
1134         int perm_ok = 0, quit, i;
1135         struct stat st;
1136
1137         if (stat(filename, &st) < 0) {
1138                 (userprovided ? logit : debug3)("no such identity: %s: %s",
1139                     filename, strerror(errno));
1140                 return NULL;
1141         }
1142         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1143         if (!perm_ok) {
1144                 if (private != NULL)
1145                         key_free(private);
1146                 return NULL;
1147         }
1148         if (private == NULL) {
1149                 if (options.batch_mode)
1150                         return NULL;
1151                 snprintf(prompt, sizeof prompt,
1152                     "Enter passphrase for key '%.100s': ", filename);
1153                 for (i = 0; i < options.number_of_password_prompts; i++) {
1154                         passphrase = read_passphrase(prompt, 0);
1155                         if (strcmp(passphrase, "") != 0) {
1156                                 private = key_load_private_type(KEY_UNSPEC,
1157                                     filename, passphrase, NULL, NULL);
1158                                 quit = 0;
1159                         } else {
1160                                 debug2("no passphrase given, try next key");
1161                                 quit = 1;
1162                         }
1163                         explicit_bzero(passphrase, strlen(passphrase));
1164                         free(passphrase);
1165                         if (private != NULL || quit)
1166                                 break;
1167                         debug2("bad passphrase given, try again...");
1168                 }
1169         }
1170         return private;
1171 }
1172
1173 /*
1174  * try keys in the following order:
1175  *      1. agent keys that are found in the config file
1176  *      2. other agent keys
1177  *      3. keys that are only listed in the config file
1178  */
1179 static void
1180 pubkey_prepare(Authctxt *authctxt)
1181 {
1182         Identity *id, *id2, *tmp;
1183         Idlist agent, files, *preferred;
1184         Key *key;
1185         AuthenticationConnection *ac;
1186         char *comment;
1187         int i, found;
1188
1189         TAILQ_INIT(&agent);     /* keys from the agent */
1190         TAILQ_INIT(&files);     /* keys from the config file */
1191         preferred = &authctxt->keys;
1192         TAILQ_INIT(preferred);  /* preferred order of keys */
1193
1194         /* list of keys stored in the filesystem and PKCS#11 */
1195         for (i = 0; i < options.num_identity_files; i++) {
1196                 key = options.identity_keys[i];
1197                 if (key && key->type == KEY_RSA1)
1198                         continue;
1199                 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1200                         continue;
1201                 options.identity_keys[i] = NULL;
1202                 id = xcalloc(1, sizeof(*id));
1203                 id->key = key;
1204                 id->filename = xstrdup(options.identity_files[i]);
1205                 id->userprovided = options.identity_file_userprovided[i];
1206                 TAILQ_INSERT_TAIL(&files, id, next);
1207         }
1208         /* Prefer PKCS11 keys that are explicitly listed */
1209         TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1210                 if (id->key == NULL || (id->key->flags & KEY_FLAG_EXT) == 0)
1211                         continue;
1212                 found = 0;
1213                 TAILQ_FOREACH(id2, &files, next) {
1214                         if (id2->key == NULL ||
1215                             (id2->key->flags & KEY_FLAG_EXT) != 0)
1216                                 continue;
1217                         if (key_equal(id->key, id2->key)) {
1218                                 TAILQ_REMOVE(&files, id, next);
1219                                 TAILQ_INSERT_TAIL(preferred, id, next);
1220                                 found = 1;
1221                                 break;
1222                         }
1223                 }
1224                 /* If IdentitiesOnly set and key not found then don't use it */
1225                 if (!found && options.identities_only) {
1226                         TAILQ_REMOVE(&files, id, next);
1227                         explicit_bzero(id, sizeof(*id));
1228                         free(id);
1229                 }
1230         }
1231         /* list of keys supported by the agent */
1232         if ((ac = ssh_get_authentication_connection())) {
1233                 for (key = ssh_get_first_identity(ac, &comment, 2);
1234                     key != NULL;
1235                     key = ssh_get_next_identity(ac, &comment, 2)) {
1236                         found = 0;
1237                         TAILQ_FOREACH(id, &files, next) {
1238                                 /* agent keys from the config file are preferred */
1239                                 if (key_equal(key, id->key)) {
1240                                         key_free(key);
1241                                         free(comment);
1242                                         TAILQ_REMOVE(&files, id, next);
1243                                         TAILQ_INSERT_TAIL(preferred, id, next);
1244                                         id->ac = ac;
1245                                         found = 1;
1246                                         break;
1247                                 }
1248                         }
1249                         if (!found && !options.identities_only) {
1250                                 id = xcalloc(1, sizeof(*id));
1251                                 id->key = key;
1252                                 id->filename = comment;
1253                                 id->ac = ac;
1254                                 TAILQ_INSERT_TAIL(&agent, id, next);
1255                         }
1256                 }
1257                 /* append remaining agent keys */
1258                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1259                         TAILQ_REMOVE(&agent, id, next);
1260                         TAILQ_INSERT_TAIL(preferred, id, next);
1261                 }
1262                 authctxt->agent = ac;
1263         }
1264         /* append remaining keys from the config file */
1265         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1266                 TAILQ_REMOVE(&files, id, next);
1267                 TAILQ_INSERT_TAIL(preferred, id, next);
1268         }
1269         TAILQ_FOREACH(id, preferred, next) {
1270                 debug2("key: %s (%p),%s", id->filename, id->key,
1271                     id->userprovided ? " explicit" : "");
1272         }
1273 }
1274
1275 static void
1276 pubkey_cleanup(Authctxt *authctxt)
1277 {
1278         Identity *id;
1279
1280         if (authctxt->agent != NULL)
1281                 ssh_close_authentication_connection(authctxt->agent);
1282         for (id = TAILQ_FIRST(&authctxt->keys); id;
1283             id = TAILQ_FIRST(&authctxt->keys)) {
1284                 TAILQ_REMOVE(&authctxt->keys, id, next);
1285                 if (id->key)
1286                         key_free(id->key);
1287                 free(id->filename);
1288                 free(id);
1289         }
1290 }
1291
1292 int
1293 userauth_pubkey(Authctxt *authctxt)
1294 {
1295         Identity *id;
1296         int sent = 0;
1297
1298         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1299                 if (id->tried++)
1300                         return (0);
1301                 /* move key to the end of the queue */
1302                 TAILQ_REMOVE(&authctxt->keys, id, next);
1303                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1304                 /*
1305                  * send a test message if we have the public key. for
1306                  * encrypted keys we cannot do this and have to load the
1307                  * private key instead
1308                  */
1309                 if (id->key != NULL) {
1310                         if (key_type_plain(id->key->type) == KEY_RSA &&
1311                             (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1312                                 debug("Skipped %s key %s for RSA/MD5 server",
1313                                     key_type(id->key), id->filename);
1314                         } else if (id->key->type != KEY_RSA1) {
1315                                 debug("Offering %s public key: %s",
1316                                     key_type(id->key), id->filename);
1317                                 sent = send_pubkey_test(authctxt, id);
1318                         }
1319                 } else {
1320                         debug("Trying private key: %s", id->filename);
1321                         id->key = load_identity_file(id->filename,
1322                             id->userprovided);
1323                         if (id->key != NULL) {
1324                                 id->isprivate = 1;
1325                                 if (key_type_plain(id->key->type) == KEY_RSA &&
1326                                     (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1327                                         debug("Skipped %s key %s for RSA/MD5 "
1328                                             "server", key_type(id->key),
1329                                             id->filename);
1330                                 } else {
1331                                         sent = sign_and_send_pubkey(
1332                                             authctxt, id);
1333                                 }
1334                                 key_free(id->key);
1335                                 id->key = NULL;
1336                         }
1337                 }
1338                 if (sent)
1339                         return (sent);
1340         }
1341         return (0);
1342 }
1343
1344 /*
1345  * Send userauth request message specifying keyboard-interactive method.
1346  */
1347 int
1348 userauth_kbdint(Authctxt *authctxt)
1349 {
1350         static int attempt = 0;
1351
1352         if (attempt++ >= options.number_of_password_prompts)
1353                 return 0;
1354         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1355         if (attempt > 1 && !authctxt->info_req_seen) {
1356                 debug3("userauth_kbdint: disable: no info_req_seen");
1357                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1358                 return 0;
1359         }
1360
1361         debug2("userauth_kbdint");
1362         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1363         packet_put_cstring(authctxt->server_user);
1364         packet_put_cstring(authctxt->service);
1365         packet_put_cstring(authctxt->method->name);
1366         packet_put_cstring("");                                 /* lang */
1367         packet_put_cstring(options.kbd_interactive_devices ?
1368             options.kbd_interactive_devices : "");
1369         packet_send();
1370
1371         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1372         return 1;
1373 }
1374
1375 /*
1376  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1377  */
1378 void
1379 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1380 {
1381         Authctxt *authctxt = ctxt;
1382         char *name, *inst, *lang, *prompt, *response;
1383         u_int num_prompts, i;
1384         int echo = 0;
1385
1386         debug2("input_userauth_info_req");
1387
1388         if (authctxt == NULL)
1389                 fatal("input_userauth_info_req: no authentication context");
1390
1391         authctxt->info_req_seen = 1;
1392
1393         name = packet_get_string(NULL);
1394         inst = packet_get_string(NULL);
1395         lang = packet_get_string(NULL);
1396         if (strlen(name) > 0)
1397                 logit("%s", name);
1398         if (strlen(inst) > 0)
1399                 logit("%s", inst);
1400         free(name);
1401         free(inst);
1402         free(lang);
1403
1404         num_prompts = packet_get_int();
1405         /*
1406          * Begin to build info response packet based on prompts requested.
1407          * We commit to providing the correct number of responses, so if
1408          * further on we run into a problem that prevents this, we have to
1409          * be sure and clean this up and send a correct error response.
1410          */
1411         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1412         packet_put_int(num_prompts);
1413
1414         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1415         for (i = 0; i < num_prompts; i++) {
1416                 prompt = packet_get_string(NULL);
1417                 echo = packet_get_char();
1418
1419                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1420
1421                 packet_put_cstring(response);
1422                 explicit_bzero(response, strlen(response));
1423                 free(response);
1424                 free(prompt);
1425         }
1426         packet_check_eom(); /* done with parsing incoming message. */
1427
1428         packet_add_padding(64);
1429         packet_send();
1430 }
1431
1432 static int
1433 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1434     u_char *data, u_int datalen)
1435 {
1436         Buffer b;
1437         struct stat st;
1438         pid_t pid;
1439         int to[2], from[2], status, version = 2;
1440
1441         debug2("ssh_keysign called");
1442
1443         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1444                 error("ssh_keysign: not installed: %s", strerror(errno));
1445                 return -1;
1446         }
1447         if (fflush(stdout) != 0)
1448                 error("ssh_keysign: fflush: %s", strerror(errno));
1449         if (pipe(to) < 0) {
1450                 error("ssh_keysign: pipe: %s", strerror(errno));
1451                 return -1;
1452         }
1453         if (pipe(from) < 0) {
1454                 error("ssh_keysign: pipe: %s", strerror(errno));
1455                 return -1;
1456         }
1457         if ((pid = fork()) < 0) {
1458                 error("ssh_keysign: fork: %s", strerror(errno));
1459                 return -1;
1460         }
1461         if (pid == 0) {
1462                 /* keep the socket on exec */
1463                 fcntl(packet_get_connection_in(), F_SETFD, 0);
1464                 permanently_drop_suid(getuid());
1465                 close(from[0]);
1466                 if (dup2(from[1], STDOUT_FILENO) < 0)
1467                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1468                 close(to[1]);
1469                 if (dup2(to[0], STDIN_FILENO) < 0)
1470                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1471                 close(from[1]);
1472                 close(to[0]);
1473                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1474                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1475                     strerror(errno));
1476         }
1477         close(from[1]);
1478         close(to[0]);
1479
1480         buffer_init(&b);
1481         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1482         buffer_put_string(&b, data, datalen);
1483         if (ssh_msg_send(to[1], version, &b) == -1)
1484                 fatal("ssh_keysign: couldn't send request");
1485
1486         if (ssh_msg_recv(from[0], &b) < 0) {
1487                 error("ssh_keysign: no reply");
1488                 buffer_free(&b);
1489                 return -1;
1490         }
1491         close(from[0]);
1492         close(to[1]);
1493
1494         while (waitpid(pid, &status, 0) < 0)
1495                 if (errno != EINTR)
1496                         break;
1497
1498         if (buffer_get_char(&b) != version) {
1499                 error("ssh_keysign: bad version");
1500                 buffer_free(&b);
1501                 return -1;
1502         }
1503         *sigp = buffer_get_string(&b, lenp);
1504         buffer_free(&b);
1505
1506         return 0;
1507 }
1508
1509 int
1510 userauth_hostbased(Authctxt *authctxt)
1511 {
1512         Key *private = NULL;
1513         Sensitive *sensitive = authctxt->sensitive;
1514         Buffer b;
1515         u_char *signature, *blob;
1516         char *chost, *pkalg, *p;
1517         const char *service;
1518         u_int blen, slen;
1519         int ok, i, found = 0;
1520
1521         /* check for a useful key */
1522         for (i = 0; i < sensitive->nkeys; i++) {
1523                 private = sensitive->keys[i];
1524                 if (private && private->type != KEY_RSA1) {
1525                         found = 1;
1526                         /* we take and free the key */
1527                         sensitive->keys[i] = NULL;
1528                         break;
1529                 }
1530         }
1531         if (!found) {
1532                 debug("No more client hostkeys for hostbased authentication.");
1533                 return 0;
1534         }
1535         if (key_to_blob(private, &blob, &blen) == 0) {
1536                 key_free(private);
1537                 return 0;
1538         }
1539         /* figure out a name for the client host */
1540         p = get_local_name(packet_get_connection_in());
1541         if (p == NULL) {
1542                 error("userauth_hostbased: cannot get local ipaddr/name");
1543                 key_free(private);
1544                 free(blob);
1545                 return 0;
1546         }
1547         xasprintf(&chost, "%s.", p);
1548         debug2("userauth_hostbased: chost %s", chost);
1549         free(p);
1550
1551         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1552             authctxt->service;
1553         pkalg = xstrdup(key_ssh_name(private));
1554         buffer_init(&b);
1555         /* construct data */
1556         buffer_put_string(&b, session_id2, session_id2_len);
1557         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1558         buffer_put_cstring(&b, authctxt->server_user);
1559         buffer_put_cstring(&b, service);
1560         buffer_put_cstring(&b, authctxt->method->name);
1561         buffer_put_cstring(&b, pkalg);
1562         buffer_put_string(&b, blob, blen);
1563         buffer_put_cstring(&b, chost);
1564         buffer_put_cstring(&b, authctxt->local_user);
1565 #ifdef DEBUG_PK
1566         buffer_dump(&b);
1567 #endif
1568         if (sensitive->external_keysign)
1569                 ok = ssh_keysign(private, &signature, &slen,
1570                     buffer_ptr(&b), buffer_len(&b));
1571         else
1572                 ok = key_sign(private, &signature, &slen,
1573                     buffer_ptr(&b), buffer_len(&b));
1574         key_free(private);
1575         buffer_free(&b);
1576         if (ok != 0) {
1577                 error("key_sign failed");
1578                 free(chost);
1579                 free(pkalg);
1580                 free(blob);
1581                 return 0;
1582         }
1583         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1584         packet_put_cstring(authctxt->server_user);
1585         packet_put_cstring(authctxt->service);
1586         packet_put_cstring(authctxt->method->name);
1587         packet_put_cstring(pkalg);
1588         packet_put_string(blob, blen);
1589         packet_put_cstring(chost);
1590         packet_put_cstring(authctxt->local_user);
1591         packet_put_string(signature, slen);
1592         explicit_bzero(signature, slen);
1593         free(signature);
1594         free(chost);
1595         free(pkalg);
1596         free(blob);
1597
1598         packet_send();
1599         return 1;
1600 }
1601
1602 /* find auth method */
1603
1604 /*
1605  * given auth method name, if configurable options permit this method fill
1606  * in auth_ident field and return true, otherwise return false.
1607  */
1608 static int
1609 authmethod_is_enabled(Authmethod *method)
1610 {
1611         if (method == NULL)
1612                 return 0;
1613         /* return false if options indicate this method is disabled */
1614         if  (method->enabled == NULL || *method->enabled == 0)
1615                 return 0;
1616         /* return false if batch mode is enabled but method needs interactive mode */
1617         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1618                 return 0;
1619         return 1;
1620 }
1621
1622 static Authmethod *
1623 authmethod_lookup(const char *name)
1624 {
1625         Authmethod *method = NULL;
1626         if (name != NULL)
1627                 for (method = authmethods; method->name != NULL; method++)
1628                         if (strcmp(name, method->name) == 0)
1629                                 return method;
1630         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1631         return NULL;
1632 }
1633
1634 /* XXX internal state */
1635 static Authmethod *current = NULL;
1636 static char *supported = NULL;
1637 static char *preferred = NULL;
1638
1639 /*
1640  * Given the authentication method list sent by the server, return the
1641  * next method we should try.  If the server initially sends a nil list,
1642  * use a built-in default list.
1643  */
1644 static Authmethod *
1645 authmethod_get(char *authlist)
1646 {
1647         char *name = NULL;
1648         u_int next;
1649
1650         /* Use a suitable default if we're passed a nil list.  */
1651         if (authlist == NULL || strlen(authlist) == 0)
1652                 authlist = options.preferred_authentications;
1653
1654         if (supported == NULL || strcmp(authlist, supported) != 0) {
1655                 debug3("start over, passed a different list %s", authlist);
1656                 free(supported);
1657                 supported = xstrdup(authlist);
1658                 preferred = options.preferred_authentications;
1659                 debug3("preferred %s", preferred);
1660                 current = NULL;
1661         } else if (current != NULL && authmethod_is_enabled(current))
1662                 return current;
1663
1664         for (;;) {
1665                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1666                         debug("No more authentication methods to try.");
1667                         current = NULL;
1668                         return NULL;
1669                 }
1670                 preferred += next;
1671                 debug3("authmethod_lookup %s", name);
1672                 debug3("remaining preferred: %s", preferred);
1673                 if ((current = authmethod_lookup(name)) != NULL &&
1674                     authmethod_is_enabled(current)) {
1675                         debug3("authmethod_is_enabled %s", name);
1676                         debug("Next authentication method: %s", name);
1677                         free(name);
1678                         return current;
1679                 }
1680                 free(name);
1681         }
1682 }
1683
1684 static char *
1685 authmethods_get(void)
1686 {
1687         Authmethod *method = NULL;
1688         Buffer b;
1689         char *list;
1690
1691         buffer_init(&b);
1692         for (method = authmethods; method->name != NULL; method++) {
1693                 if (authmethod_is_enabled(method)) {
1694                         if (buffer_len(&b) > 0)
1695                                 buffer_append(&b, ",", 1);
1696                         buffer_append(&b, method->name, strlen(method->name));
1697                 }
1698         }
1699         buffer_append(&b, "\0", 1);
1700         list = xstrdup(buffer_ptr(&b));
1701         buffer_free(&b);
1702         return list;
1703 }
1704