crypto/openssh/sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.204 2014/02/02 03:44:32 djm Exp $ */
   2 /*
   3  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   4  * Copyright (c) 2008 Damien Miller.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include "includes.h"
  28
  29 #include <sys/types.h>
  30 #include <sys/socket.h>
  31 #include <sys/wait.h>
  32 #include <sys/stat.h>
  33
  34 #include <errno.h>
  35 #include <fcntl.h>
  36 #include <netdb.h>
  37 #include <pwd.h>
  38 #include <signal.h>
  39 #include <stdarg.h>
  40 #include <stdio.h>
  41 #include <string.h>
  42 #include <unistd.h>
  43 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS)
  44 #include <vis.h>
  45 #endif
  46
  47 #include "openbsd-compat/sys-queue.h"
  48
  49 #include "xmalloc.h"
  50 #include "ssh.h"
  51 #include "ssh2.h"
  52 #include "buffer.h"
  53 #include "packet.h"
  54 #include "compat.h"
  55 #include "cipher.h"
  56 #include "key.h"
  57 #include "kex.h"
  58 #include "myproposal.h"
  59 #include "sshconnect.h"
  60 #include "authfile.h"
  61 #include "dh.h"
  62 #include "authfd.h"
  63 #include "log.h"
  64 #include "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
  74 #ifdef GSSAPI
  75 #include "ssh-gss.h"
  76 #endif
  77
  78 /* import */
  79 extern char *client_version_string;
  80 extern char *server_version_string;
  81 extern Options options;
  82
  83 /*
  84  * SSH2 key exchange
  85  */
  86
  87 u_char *session_id2 = NULL;
  88 u_int session_id2_len = 0;
  89
  90 char *xxx_host;
  91 struct sockaddr *xxx_hostaddr;
  92
  93 Kex *xxx_kex = NULL;
  94
  95 static int
  96 verify_host_key_callback(Key *hostkey)
  97 {
  98         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
  99                 fatal("Host key verification failed.");
 100         return 0;
 101 }
 102
 103 static char *
 104 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
 105 {
 106         char *oavail, *avail, *first, *last, *alg, *hostname, *ret;
 107         size_t maxlen;
 108         struct hostkeys *hostkeys;
 109         int ktype;
 110         u_int i;
 111
 112         /* Find all hostkeys for this hostname */
 113         get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
 114         hostkeys = init_hostkeys();
 115         for (i = 0; i < options.num_user_hostfiles; i++)
 116                 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]);
 117         for (i = 0; i < options.num_system_hostfiles; i++)
 118                 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]);
 119
 120         oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG);
 121         maxlen = strlen(avail) + 1;
 122         first = xmalloc(maxlen);
 123         last = xmalloc(maxlen);
 124         *first = *last = '\0';
 125
 126 #define ALG_APPEND(to, from) \
 127         do { \
 128                 if (*to != '\0') \
 129                         strlcat(to, ",", maxlen); \
 130                 strlcat(to, from, maxlen); \
 131         } while (0)
 132
 133         while ((alg = strsep(&avail, ",")) && *alg != '\0') {
 134                 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC)
 135                         fatal("%s: unknown alg %s", __func__, alg);
 136                 if (lookup_key_in_hostkeys_by_type(hostkeys,
 137                     key_type_plain(ktype), NULL))
 138                         ALG_APPEND(first, alg);
 139                 else
 140                         ALG_APPEND(last, alg);
 141         }
 142 #undef ALG_APPEND
 143         xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last);
 144         if (*first != '\0')
 145                 debug3("%s: prefer hostkeyalgs: %s", __func__, first);
 146
 147         free(first);
 148         free(last);
 149         free(hostname);
 150         free(oavail);
 151         free_hostkeys(hostkeys);
 152
 153         return ret;
 154 }
 155
 156 void
 157 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
 158 {
 159         Kex *kex;
 160
 161         xxx_host = host;
 162         xxx_hostaddr = hostaddr;
 163
 164         if (options.ciphers == (char *)-1) {
 165                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 166                 options.ciphers = NULL;
 167         }
 168         if (options.ciphers != NULL) {
 169                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 170                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 171         }
 172         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 173             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 174         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 175             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 176         if (options.compression) {
 177                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 178                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 179         } else {
 180                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 181                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 182         }
 183         if (options.macs != NULL) {
 184                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 185                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 186         }
 187         if (options.hostkeyalgorithms != NULL)
 188                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 189                     compat_pkalg_proposal(options.hostkeyalgorithms);
 190         else {
 191                 /* Prefer algorithms that we already have keys for */
 192                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 193                     compat_pkalg_proposal(
 194                     order_hostkeyalgs(host, hostaddr, port));
 195         }
 196         if (options.kex_algorithms != NULL)
 197                 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
 198         myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
 199             myproposal[PROPOSAL_KEX_ALGS]);
 200
 201         if (options.rekey_limit || options.rekey_interval)
 202                 packet_set_rekey_limits((u_int32_t)options.rekey_limit,
 203                     (time_t)options.rekey_interval);
 204
 205         /* start key exchange */
 206         kex = kex_setup(myproposal);
 207         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 208         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 209         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 210         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 211         kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
 212         kex->kex[KEX_C25519_SHA256] = kexc25519_client;
 213         kex->client_version_string=client_version_string;
 214         kex->server_version_string=server_version_string;
 215         kex->verify_host_key=&verify_host_key_callback;
 216
 217         xxx_kex = kex;
 218
 219         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 220
 221         if (options.use_roaming && !kex->roaming) {
 222                 debug("Roaming not allowed by server");
 223                 options.use_roaming = 0;
 224         }
 225
 226         session_id2 = kex->session_id;
 227         session_id2_len = kex->session_id_len;
 228
 229 #ifdef DEBUG_KEXDH
 230         /* send 1st encrypted/maced/compressed message */
 231         packet_start(SSH2_MSG_IGNORE);
 232         packet_put_cstring("markus");
 233         packet_send();
 234         packet_write_wait();
 235 #endif
 236 }
 237
 238 /*
 239  * Authenticate user
 240  */
 241
 242 typedef struct Authctxt Authctxt;
 243 typedef struct Authmethod Authmethod;
 244 typedef struct identity Identity;
 245 typedef struct idlist Idlist;
 246
 247 struct identity {
 248         TAILQ_ENTRY(identity) next;
 249         AuthenticationConnection *ac;   /* set if agent supports key */
 250         Key     *key;                   /* public/private key */
 251         char    *filename;              /* comment for agent-only keys */
 252         int     tried;
 253         int     isprivate;              /* key points to the private key */
 254         int     userprovided;
 255 };
 256 TAILQ_HEAD(idlist, identity);
 257
 258 struct Authctxt {
 259         const char *server_user;
 260         const char *local_user;
 261         const char *host;
 262         const char *service;
 263         Authmethod *method;
 264         sig_atomic_t success;
 265         char *authlist;
 266         /* pubkey */
 267         Idlist keys;
 268         AuthenticationConnection *agent;
 269         /* hostbased */
 270         Sensitive *sensitive;
 271         /* kbd-interactive */
 272         int info_req_seen;
 273         /* generic */
 274         void *methoddata;
 275 };
 276 struct Authmethod {
 277         char    *name;          /* string to compare against server's list */
 278         int     (*userauth)(Authctxt *authctxt);
 279         void    (*cleanup)(Authctxt *authctxt);
 280         int     *enabled;       /* flag in option struct that enables method */
 281         int     *batch_flag;    /* flag in option struct that disables method */
 282 };
 283
 284 void    input_userauth_success(int, u_int32_t, void *);
 285 void    input_userauth_success_unexpected(int, u_int32_t, void *);
 286 void    input_userauth_failure(int, u_int32_t, void *);
 287 void    input_userauth_banner(int, u_int32_t, void *);
 288 void    input_userauth_error(int, u_int32_t, void *);
 289 void    input_userauth_info_req(int, u_int32_t, void *);
 290 void    input_userauth_pk_ok(int, u_int32_t, void *);
 291 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 292
 293 int     userauth_none(Authctxt *);
 294 int     userauth_pubkey(Authctxt *);
 295 int     userauth_passwd(Authctxt *);
 296 int     userauth_kbdint(Authctxt *);
 297 int     userauth_hostbased(Authctxt *);
 298
 299 #ifdef GSSAPI
 300 int     userauth_gssapi(Authctxt *authctxt);
 301 void    input_gssapi_response(int type, u_int32_t, void *);
 302 void    input_gssapi_token(int type, u_int32_t, void *);
 303 void    input_gssapi_hash(int type, u_int32_t, void *);
 304 void    input_gssapi_error(int, u_int32_t, void *);
 305 void    input_gssapi_errtok(int, u_int32_t, void *);
 306 #endif
 307
 308 void    userauth(Authctxt *, char *);
 309
 310 static int sign_and_send_pubkey(Authctxt *, Identity *);
 311 static void pubkey_prepare(Authctxt *);
 312 static void pubkey_cleanup(Authctxt *);
 313 static Key *load_identity_file(char *, int);
 314
 315 static Authmethod *authmethod_get(char *authlist);
 316 static Authmethod *authmethod_lookup(const char *name);
 317 static char *authmethods_get(void);
 318
 319 Authmethod authmethods[] = {
 320 #ifdef GSSAPI
 321         {"gssapi-with-mic",
 322                 userauth_gssapi,
 323                 NULL,
 324                 &options.gss_authentication,
 325                 NULL},
 326 #endif
 327         {"hostbased",
 328                 userauth_hostbased,
 329                 NULL,
 330                 &options.hostbased_authentication,
 331                 NULL},
 332         {"publickey",
 333                 userauth_pubkey,
 334                 NULL,
 335                 &options.pubkey_authentication,
 336                 NULL},
 337         {"keyboard-interactive",
 338                 userauth_kbdint,
 339                 NULL,
 340                 &options.kbd_interactive_authentication,
 341                 &options.batch_mode},
 342         {"password",
 343                 userauth_passwd,
 344                 NULL,
 345                 &options.password_authentication,
 346                 &options.batch_mode},
 347         {"none",
 348                 userauth_none,
 349                 NULL,
 350                 NULL,
 351                 NULL},
 352         {NULL, NULL, NULL, NULL, NULL}
 353 };
 354
 355 void
 356 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 357     Sensitive *sensitive)
 358 {
 359         Authctxt authctxt;
 360         int type;
 361
 362         if (options.challenge_response_authentication)
 363                 options.kbd_interactive_authentication = 1;
 364
 365         packet_start(SSH2_MSG_SERVICE_REQUEST);
 366         packet_put_cstring("ssh-userauth");
 367         packet_send();
 368         debug("SSH2_MSG_SERVICE_REQUEST sent");
 369         packet_write_wait();
 370         type = packet_read();
 371         if (type != SSH2_MSG_SERVICE_ACCEPT)
 372                 fatal("Server denied authentication request: %d", type);
 373         if (packet_remaining() > 0) {
 374                 char *reply = packet_get_string(NULL);
 375                 debug2("service_accept: %s", reply);
 376                 free(reply);
 377         } else {
 378                 debug2("buggy server: service_accept w/o service");
 379         }
 380         packet_check_eom();
 381         debug("SSH2_MSG_SERVICE_ACCEPT received");
 382
 383         if (options.preferred_authentications == NULL)
 384                 options.preferred_authentications = authmethods_get();
 385
 386         /* setup authentication context */
 387         memset(&authctxt, 0, sizeof(authctxt));
 388         pubkey_prepare(&authctxt);
 389         authctxt.server_user = server_user;
 390         authctxt.local_user = local_user;
 391         authctxt.host = host;
 392         authctxt.service = "ssh-connection";            /* service name */
 393         authctxt.success = 0;
 394         authctxt.method = authmethod_lookup("none");
 395         authctxt.authlist = NULL;
 396         authctxt.methoddata = NULL;
 397         authctxt.sensitive = sensitive;
 398         authctxt.info_req_seen = 0;
 399         if (authctxt.method == NULL)
 400                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 401
 402         /* initial userauth request */
 403         userauth_none(&authctxt);
 404
 405         dispatch_init(&input_userauth_error);
 406         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 407         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 408         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 409         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 410
 411         pubkey_cleanup(&authctxt);
 412         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 413
 414         debug("Authentication succeeded (%s).", authctxt.method->name);
 415 }
 416
 417 void
 418 userauth(Authctxt *authctxt, char *authlist)
 419 {
 420         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 421                 authctxt->method->cleanup(authctxt);
 422
 423         free(authctxt->methoddata);
 424         authctxt->methoddata = NULL;
 425         if (authlist == NULL) {
 426                 authlist = authctxt->authlist;
 427         } else {
 428                 free(authctxt->authlist);
 429                 authctxt->authlist = authlist;
 430         }
 431         for (;;) {
 432                 Authmethod *method = authmethod_get(authlist);
 433                 if (method == NULL)
 434                         fatal("Permission denied (%s).", authlist);
 435                 authctxt->method = method;
 436
 437                 /* reset the per method handler */
 438                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 439                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 440
 441                 /* and try new method */
 442                 if (method->userauth(authctxt) != 0) {
 443                         debug2("we sent a %s packet, wait for reply", method->name);
 444                         break;
 445                 } else {
 446                         debug2("we did not send a packet, disable method");
 447                         method->enabled = NULL;
 448                 }
 449         }
 450 }
 451
 452 /* ARGSUSED */
 453 void
 454 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 455 {
 456         fatal("input_userauth_error: bad message during authentication: "
 457             "type %d", type);
 458 }
 459
 460 /* ARGSUSED */
 461 void
 462 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 463 {
 464         char *msg, *raw, *lang;
 465         u_int len;
 466
 467         debug3("input_userauth_banner");
 468         raw = packet_get_string(&len);
 469         lang = packet_get_string(NULL);
 470         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
 471                 if (len > 65536)
 472                         len = 65536;
 473                 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
 474                 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH);
 475                 fprintf(stderr, "%s", msg);
 476                 free(msg);
 477         }
 478         free(raw);
 479         free(lang);
 480 }
 481
 482 /* ARGSUSED */
 483 void
 484 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 485 {
 486         Authctxt *authctxt = ctxt;
 487
 488         if (authctxt == NULL)
 489                 fatal("input_userauth_success: no authentication context");
 490         free(authctxt->authlist);
 491         authctxt->authlist = NULL;
 492         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 493                 authctxt->method->cleanup(authctxt);
 494         free(authctxt->methoddata);
 495         authctxt->methoddata = NULL;
 496         authctxt->success = 1;                  /* break out */
 497 }
 498
 499 void
 500 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
 501 {
 502         Authctxt *authctxt = ctxt;
 503
 504         if (authctxt == NULL)
 505                 fatal("%s: no authentication context", __func__);
 506
 507         fatal("Unexpected authentication success during %s.",
 508             authctxt->method->name);
 509 }
 510
 511 /* ARGSUSED */
 512 void
 513 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 514 {
 515         Authctxt *authctxt = ctxt;
 516         char *authlist = NULL;
 517         int partial;
 518
 519         if (authctxt == NULL)
 520                 fatal("input_userauth_failure: no authentication context");
 521
 522         authlist = packet_get_string(NULL);
 523         partial = packet_get_char();
 524         packet_check_eom();
 525
 526         if (partial != 0) {
 527                 logit("Authenticated with partial success.");
 528                 /* reset state */
 529                 pubkey_cleanup(authctxt);
 530                 pubkey_prepare(authctxt);
 531         }
 532         debug("Authentications that can continue: %s", authlist);
 533
 534         userauth(authctxt, authlist);
 535 }
 536
 537 /* ARGSUSED */
 538 void
 539 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 540 {
 541         Authctxt *authctxt = ctxt;
 542         Key *key = NULL;
 543         Identity *id = NULL;
 544         Buffer b;
 545         int pktype, sent = 0;
 546         u_int alen, blen;
 547         char *pkalg, *fp;
 548         u_char *pkblob;
 549
 550         if (authctxt == NULL)
 551                 fatal("input_userauth_pk_ok: no authentication context");
 552         if (datafellows & SSH_BUG_PKOK) {
 553                 /* this is similar to SSH_BUG_PKAUTH */
 554                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 555                 pkblob = packet_get_string(&blen);
 556                 buffer_init(&b);
 557                 buffer_append(&b, pkblob, blen);
 558                 pkalg = buffer_get_string(&b, &alen);
 559                 buffer_free(&b);
 560         } else {
 561                 pkalg = packet_get_string(&alen);
 562                 pkblob = packet_get_string(&blen);
 563         }
 564         packet_check_eom();
 565
 566         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 567
 568         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 569                 debug("unknown pkalg %s", pkalg);
 570                 goto done;
 571         }
 572         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 573                 debug("no key from blob. pkalg %s", pkalg);
 574                 goto done;
 575         }
 576         if (key->type != pktype) {
 577                 error("input_userauth_pk_ok: type mismatch "
 578                     "for decoded key (received %d, expected %d)",
 579                     key->type, pktype);
 580                 goto done;
 581         }
 582         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 583         debug2("input_userauth_pk_ok: fp %s", fp);
 584         free(fp);
 585
 586         /*
 587          * search keys in the reverse order, because last candidate has been
 588          * moved to the end of the queue.  this also avoids confusion by
 589          * duplicate keys
 590          */
 591         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 592                 if (key_equal(key, id->key)) {
 593                         sent = sign_and_send_pubkey(authctxt, id);
 594                         break;
 595                 }
 596         }
 597 done:
 598         if (key != NULL)
 599                 key_free(key);
 600         free(pkalg);
 601         free(pkblob);
 602
 603         /* try another method if we did not send a packet */
 604         if (sent == 0)
 605                 userauth(authctxt, NULL);
 606 }
 607
 608 #ifdef GSSAPI
 609 int
 610 userauth_gssapi(Authctxt *authctxt)
 611 {
 612         Gssctxt *gssctxt = NULL;
 613         static gss_OID_set gss_supported = NULL;
 614         static u_int mech = 0;
 615         OM_uint32 min;
 616         int ok = 0;
 617
 618         /* Try one GSSAPI method at a time, rather than sending them all at
 619          * once. */
 620
 621         if (gss_supported == NULL)
 622                 gss_indicate_mechs(&min, &gss_supported);
 623
 624         /* Check to see if the mechanism is usable before we offer it */
 625         while (mech < gss_supported->count && !ok) {
 626                 /* My DER encoding requires length<128 */
 627                 if (gss_supported->elements[mech].length < 128 &&
 628                     ssh_gssapi_check_mechanism(&gssctxt,
 629                     &gss_supported->elements[mech], authctxt->host)) {
 630                         ok = 1; /* Mechanism works */
 631                 } else {
 632                         mech++;
 633                 }
 634         }
 635
 636         if (!ok)
 637                 return 0;
 638
 639         authctxt->methoddata=(void *)gssctxt;
 640
 641         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 642         packet_put_cstring(authctxt->server_user);
 643         packet_put_cstring(authctxt->service);
 644         packet_put_cstring(authctxt->method->name);
 645
 646         packet_put_int(1);
 647
 648         packet_put_int((gss_supported->elements[mech].length) + 2);
 649         packet_put_char(SSH_GSS_OIDTYPE);
 650         packet_put_char(gss_supported->elements[mech].length);
 651         packet_put_raw(gss_supported->elements[mech].elements,
 652             gss_supported->elements[mech].length);
 653
 654         packet_send();
 655
 656         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 657         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 658         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 659         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 660
 661         mech++; /* Move along to next candidate */
 662
 663         return 1;
 664 }
 665
 666 static OM_uint32
 667 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 668 {
 669         Authctxt *authctxt = ctxt;
 670         Gssctxt *gssctxt = authctxt->methoddata;
 671         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 672         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 673         gss_buffer_desc gssbuf;
 674         OM_uint32 status, ms, flags;
 675         Buffer b;
 676
 677         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 678             recv_tok, &send_tok, &flags);
 679
 680         if (send_tok.length > 0) {
 681                 if (GSS_ERROR(status))
 682                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 683                 else
 684                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 685
 686                 packet_put_string(send_tok.value, send_tok.length);
 687                 packet_send();
 688                 gss_release_buffer(&ms, &send_tok);
 689         }
 690
 691         if (status == GSS_S_COMPLETE) {
 692                 /* send either complete or MIC, depending on mechanism */
 693                 if (!(flags & GSS_C_INTEG_FLAG)) {
 694                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 695                         packet_send();
 696                 } else {
 697                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 698                             authctxt->service, "gssapi-with-mic");
 699
 700                         gssbuf.value = buffer_ptr(&b);
 701                         gssbuf.length = buffer_len(&b);
 702
 703                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 704
 705                         if (!GSS_ERROR(status)) {
 706                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 707                                 packet_put_string(mic.value, mic.length);
 708
 709                                 packet_send();
 710                         }
 711
 712                         buffer_free(&b);
 713                         gss_release_buffer(&ms, &mic);
 714                 }
 715         }
 716
 717         return status;
 718 }
 719
 720 /* ARGSUSED */
 721 void
 722 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 723 {
 724         Authctxt *authctxt = ctxt;
 725         Gssctxt *gssctxt;
 726         int oidlen;
 727         char *oidv;
 728
 729         if (authctxt == NULL)
 730                 fatal("input_gssapi_response: no authentication context");
 731         gssctxt = authctxt->methoddata;
 732
 733         /* Setup our OID */
 734         oidv = packet_get_string(&oidlen);
 735
 736         if (oidlen <= 2 ||
 737             oidv[0] != SSH_GSS_OIDTYPE ||
 738             oidv[1] != oidlen - 2) {
 739                 free(oidv);
 740                 debug("Badly encoded mechanism OID received");
 741                 userauth(authctxt, NULL);
 742                 return;
 743         }
 744
 745         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 746                 fatal("Server returned different OID than expected");
 747
 748         packet_check_eom();
 749
 750         free(oidv);
 751
 752         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 753                 /* Start again with next method on list */
 754                 debug("Trying to start again");
 755                 userauth(authctxt, NULL);
 756                 return;
 757         }
 758 }
 759
 760 /* ARGSUSED */
 761 void
 762 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 763 {
 764         Authctxt *authctxt = ctxt;
 765         gss_buffer_desc recv_tok;
 766         OM_uint32 status;
 767         u_int slen;
 768
 769         if (authctxt == NULL)
 770                 fatal("input_gssapi_response: no authentication context");
 771
 772         recv_tok.value = packet_get_string(&slen);
 773         recv_tok.length = slen; /* safe typecast */
 774
 775         packet_check_eom();
 776
 777         status = process_gssapi_token(ctxt, &recv_tok);
 778
 779         free(recv_tok.value);
 780
 781         if (GSS_ERROR(status)) {
 782                 /* Start again with the next method in the list */
 783                 userauth(authctxt, NULL);
 784                 return;
 785         }
 786 }
 787
 788 /* ARGSUSED */
 789 void
 790 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 791 {
 792         Authctxt *authctxt = ctxt;
 793         Gssctxt *gssctxt;
 794         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 795         gss_buffer_desc recv_tok;
 796         OM_uint32 ms;
 797         u_int len;
 798
 799         if (authctxt == NULL)
 800                 fatal("input_gssapi_response: no authentication context");
 801         gssctxt = authctxt->methoddata;
 802
 803         recv_tok.value = packet_get_string(&len);
 804         recv_tok.length = len;
 805
 806         packet_check_eom();
 807
 808         /* Stick it into GSSAPI and see what it says */
 809         (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 810             &recv_tok, &send_tok, NULL);
 811
 812         free(recv_tok.value);
 813         gss_release_buffer(&ms, &send_tok);
 814
 815         /* Server will be returning a failed packet after this one */
 816 }
 817
 818 /* ARGSUSED */
 819 void
 820 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 821 {
 822         char *msg;
 823         char *lang;
 824
 825         /* maj */(void)packet_get_int();
 826         /* min */(void)packet_get_int();
 827         msg=packet_get_string(NULL);
 828         lang=packet_get_string(NULL);
 829
 830         packet_check_eom();
 831
 832         debug("Server GSSAPI Error:\n%s", msg);
 833         free(msg);
 834         free(lang);
 835 }
 836 #endif /* GSSAPI */
 837
 838 int
 839 userauth_none(Authctxt *authctxt)
 840 {
 841         /* initial userauth request */
 842         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 843         packet_put_cstring(authctxt->server_user);
 844         packet_put_cstring(authctxt->service);
 845         packet_put_cstring(authctxt->method->name);
 846         packet_send();
 847         return 1;
 848 }
 849
 850 int
 851 userauth_passwd(Authctxt *authctxt)
 852 {
 853         static int attempt = 0;
 854         char prompt[150];
 855         char *password;
 856         const char *host = options.host_key_alias ?  options.host_key_alias :
 857             authctxt->host;
 858
 859         if (attempt++ >= options.number_of_password_prompts)
 860                 return 0;
 861
 862         if (attempt != 1)
 863                 error("Permission denied, please try again.");
 864
 865         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 866             authctxt->server_user, host);
 867         password = read_passphrase(prompt, 0);
 868         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 869         packet_put_cstring(authctxt->server_user);
 870         packet_put_cstring(authctxt->service);
 871         packet_put_cstring(authctxt->method->name);
 872         packet_put_char(0);
 873         packet_put_cstring(password);
 874         explicit_bzero(password, strlen(password));
 875         free(password);
 876         packet_add_padding(64);
 877         packet_send();
 878
 879         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 880             &input_userauth_passwd_changereq);
 881
 882         return 1;
 883 }
 884
 885 /*
 886  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 887  */
 888 /* ARGSUSED */
 889 void
 890 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 891 {
 892         Authctxt *authctxt = ctxt;
 893         char *info, *lang, *password = NULL, *retype = NULL;
 894         char prompt[150];
 895         const char *host = options.host_key_alias ? options.host_key_alias :
 896             authctxt->host;
 897
 898         debug2("input_userauth_passwd_changereq");
 899
 900         if (authctxt == NULL)
 901                 fatal("input_userauth_passwd_changereq: "
 902                     "no authentication context");
 903
 904         info = packet_get_string(NULL);
 905         lang = packet_get_string(NULL);
 906         if (strlen(info) > 0)
 907                 logit("%s", info);
 908         free(info);
 909         free(lang);
 910         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 911         packet_put_cstring(authctxt->server_user);
 912         packet_put_cstring(authctxt->service);
 913         packet_put_cstring(authctxt->method->name);
 914         packet_put_char(1);                     /* additional info */
 915         snprintf(prompt, sizeof(prompt),
 916             "Enter %.30s@%.128s's old password: ",
 917             authctxt->server_user, host);
 918         password = read_passphrase(prompt, 0);
 919         packet_put_cstring(password);
 920         explicit_bzero(password, strlen(password));
 921         free(password);
 922         password = NULL;
 923         while (password == NULL) {
 924                 snprintf(prompt, sizeof(prompt),
 925                     "Enter %.30s@%.128s's new password: ",
 926                     authctxt->server_user, host);
 927                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 928                 if (password == NULL) {
 929                         /* bail out */
 930                         return;
 931                 }
 932                 snprintf(prompt, sizeof(prompt),
 933                     "Retype %.30s@%.128s's new password: ",
 934                     authctxt->server_user, host);
 935                 retype = read_passphrase(prompt, 0);
 936                 if (strcmp(password, retype) != 0) {
 937                         explicit_bzero(password, strlen(password));
 938                         free(password);
 939                         logit("Mismatch; try again, EOF to quit.");
 940                         password = NULL;
 941                 }
 942                 explicit_bzero(retype, strlen(retype));
 943                 free(retype);
 944         }
 945         packet_put_cstring(password);
 946         explicit_bzero(password, strlen(password));
 947         free(password);
 948         packet_add_padding(64);
 949         packet_send();
 950
 951         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 952             &input_userauth_passwd_changereq);
 953 }
 954
 955 static int
 956 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
 957     u_char *data, u_int datalen)
 958 {
 959         Key *prv;
 960         int ret;
 961
 962         /* the agent supports this key */
 963         if (id->ac)
 964                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
 965                     data, datalen));
 966         /*
 967          * we have already loaded the private key or
 968          * the private key is stored in external hardware
 969          */
 970         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
 971                 return (key_sign(id->key, sigp, lenp, data, datalen));
 972         /* load the private key from the file */
 973         if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL)
 974                 return (-1);
 975         ret = key_sign(prv, sigp, lenp, data, datalen);
 976         key_free(prv);
 977         return (ret);
 978 }
 979
 980 static int
 981 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
 982 {
 983         Buffer b;
 984         u_char *blob, *signature;
 985         u_int bloblen, slen;
 986         u_int skip = 0;
 987         int ret = -1;
 988         int have_sig = 1;
 989         char *fp;
 990
 991         fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 992         debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp);
 993         free(fp);
 994
 995         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
 996                 /* we cannot handle this key */
 997                 debug3("sign_and_send_pubkey: cannot handle key");
 998                 return 0;
 999         }
1000         /* data to be signed */
1001         buffer_init(&b);
1002         if (datafellows & SSH_OLD_SESSIONID) {
1003                 buffer_append(&b, session_id2, session_id2_len);
1004                 skip = session_id2_len;
1005         } else {
1006                 buffer_put_string(&b, session_id2, session_id2_len);
1007                 skip = buffer_len(&b);
1008         }
1009         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1010         buffer_put_cstring(&b, authctxt->server_user);
1011         buffer_put_cstring(&b,
1012             datafellows & SSH_BUG_PKSERVICE ?
1013             "ssh-userauth" :
1014             authctxt->service);
1015         if (datafellows & SSH_BUG_PKAUTH) {
1016                 buffer_put_char(&b, have_sig);
1017         } else {
1018                 buffer_put_cstring(&b, authctxt->method->name);
1019                 buffer_put_char(&b, have_sig);
1020                 buffer_put_cstring(&b, key_ssh_name(id->key));
1021         }
1022         buffer_put_string(&b, blob, bloblen);
1023
1024         /* generate signature */
1025         ret = identity_sign(id, &signature, &slen,
1026             buffer_ptr(&b), buffer_len(&b));
1027         if (ret == -1) {
1028                 free(blob);
1029                 buffer_free(&b);
1030                 return 0;
1031         }
1032 #ifdef DEBUG_PK
1033         buffer_dump(&b);
1034 #endif
1035         if (datafellows & SSH_BUG_PKSERVICE) {
1036                 buffer_clear(&b);
1037                 buffer_append(&b, session_id2, session_id2_len);
1038                 skip = session_id2_len;
1039                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1040                 buffer_put_cstring(&b, authctxt->server_user);
1041                 buffer_put_cstring(&b, authctxt->service);
1042                 buffer_put_cstring(&b, authctxt->method->name);
1043                 buffer_put_char(&b, have_sig);
1044                 if (!(datafellows & SSH_BUG_PKAUTH))
1045                         buffer_put_cstring(&b, key_ssh_name(id->key));
1046                 buffer_put_string(&b, blob, bloblen);
1047         }
1048         free(blob);
1049
1050         /* append signature */
1051         buffer_put_string(&b, signature, slen);
1052         free(signature);
1053
1054         /* skip session id and packet type */
1055         if (buffer_len(&b) < skip + 1)
1056                 fatal("userauth_pubkey: internal error");
1057         buffer_consume(&b, skip + 1);
1058
1059         /* put remaining data from buffer into packet */
1060         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1061         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1062         buffer_free(&b);
1063         packet_send();
1064
1065         return 1;
1066 }
1067
1068 static int
1069 send_pubkey_test(Authctxt *authctxt, Identity *id)
1070 {
1071         u_char *blob;
1072         u_int bloblen, have_sig = 0;
1073
1074         debug3("send_pubkey_test");
1075
1076         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1077                 /* we cannot handle this key */
1078                 debug3("send_pubkey_test: cannot handle key");
1079                 return 0;
1080         }
1081         /* register callback for USERAUTH_PK_OK message */
1082         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1083
1084         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1085         packet_put_cstring(authctxt->server_user);
1086         packet_put_cstring(authctxt->service);
1087         packet_put_cstring(authctxt->method->name);
1088         packet_put_char(have_sig);
1089         if (!(datafellows & SSH_BUG_PKAUTH))
1090                 packet_put_cstring(key_ssh_name(id->key));
1091         packet_put_string(blob, bloblen);
1092         free(blob);
1093         packet_send();
1094         return 1;
1095 }
1096
1097 static Key *
1098 load_identity_file(char *filename, int userprovided)
1099 {
1100         Key *private;
1101         char prompt[300], *passphrase;
1102         int perm_ok = 0, quit, i;
1103         struct stat st;
1104
1105         if (stat(filename, &st) < 0) {
1106                 (userprovided ? logit : debug3)("no such identity: %s: %s",
1107                     filename, strerror(errno));
1108                 return NULL;
1109         }
1110         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1111         if (!perm_ok) {
1112                 if (private != NULL)
1113                         key_free(private);
1114                 return NULL;
1115         }
1116         if (private == NULL) {
1117                 if (options.batch_mode)
1118                         return NULL;
1119                 snprintf(prompt, sizeof prompt,
1120                     "Enter passphrase for key '%.100s': ", filename);
1121                 for (i = 0; i < options.number_of_password_prompts; i++) {
1122                         passphrase = read_passphrase(prompt, 0);
1123                         if (strcmp(passphrase, "") != 0) {
1124                                 private = key_load_private_type(KEY_UNSPEC,
1125                                     filename, passphrase, NULL, NULL);
1126                                 quit = 0;
1127                         } else {
1128                                 debug2("no passphrase given, try next key");
1129                                 quit = 1;
1130                         }
1131                         explicit_bzero(passphrase, strlen(passphrase));
1132                         free(passphrase);
1133                         if (private != NULL || quit)
1134                                 break;
1135                         debug2("bad passphrase given, try again...");
1136                 }
1137         }
1138         return private;
1139 }
1140
1141 /*
1142  * try keys in the following order:
1143  *      1. agent keys that are found in the config file
1144  *      2. other agent keys
1145  *      3. keys that are only listed in the config file
1146  */
1147 static void
1148 pubkey_prepare(Authctxt *authctxt)
1149 {
1150         Identity *id, *id2, *tmp;
1151         Idlist agent, files, *preferred;
1152         Key *key;
1153         AuthenticationConnection *ac;
1154         char *comment;
1155         int i, found;
1156
1157         TAILQ_INIT(&agent);     /* keys from the agent */
1158         TAILQ_INIT(&files);     /* keys from the config file */
1159         preferred = &authctxt->keys;
1160         TAILQ_INIT(preferred);  /* preferred order of keys */
1161
1162         /* list of keys stored in the filesystem and PKCS#11 */
1163         for (i = 0; i < options.num_identity_files; i++) {
1164                 key = options.identity_keys[i];
1165                 if (key && key->type == KEY_RSA1)
1166                         continue;
1167                 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1168                         continue;
1169                 options.identity_keys[i] = NULL;
1170                 id = xcalloc(1, sizeof(*id));
1171                 id->key = key;
1172                 id->filename = xstrdup(options.identity_files[i]);
1173                 id->userprovided = options.identity_file_userprovided[i];
1174                 TAILQ_INSERT_TAIL(&files, id, next);
1175         }
1176         /* Prefer PKCS11 keys that are explicitly listed */
1177         TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1178                 if (id->key == NULL || (id->key->flags & KEY_FLAG_EXT) == 0)
1179                         continue;
1180                 found = 0;
1181                 TAILQ_FOREACH(id2, &files, next) {
1182                         if (id2->key == NULL ||
1183                             (id2->key->flags & KEY_FLAG_EXT) != 0)
1184                                 continue;
1185                         if (key_equal(id->key, id2->key)) {
1186                                 TAILQ_REMOVE(&files, id, next);
1187                                 TAILQ_INSERT_TAIL(preferred, id, next);
1188                                 found = 1;
1189                                 break;
1190                         }
1191                 }
1192                 /* If IdentitiesOnly set and key not found then don't use it */
1193                 if (!found && options.identities_only) {
1194                         TAILQ_REMOVE(&files, id, next);
1195                         explicit_bzero(id, sizeof(*id));
1196                         free(id);
1197                 }
1198         }
1199         /* list of keys supported by the agent */
1200         if ((ac = ssh_get_authentication_connection())) {
1201                 for (key = ssh_get_first_identity(ac, &comment, 2);
1202                     key != NULL;
1203                     key = ssh_get_next_identity(ac, &comment, 2)) {
1204                         found = 0;
1205                         TAILQ_FOREACH(id, &files, next) {
1206                                 /* agent keys from the config file are preferred */
1207                                 if (key_equal(key, id->key)) {
1208                                         key_free(key);
1209                                         free(comment);
1210                                         TAILQ_REMOVE(&files, id, next);
1211                                         TAILQ_INSERT_TAIL(preferred, id, next);
1212                                         id->ac = ac;
1213                                         found = 1;
1214                                         break;
1215                                 }
1216                         }
1217                         if (!found && !options.identities_only) {
1218                                 id = xcalloc(1, sizeof(*id));
1219                                 id->key = key;
1220                                 id->filename = comment;
1221                                 id->ac = ac;
1222                                 TAILQ_INSERT_TAIL(&agent, id, next);
1223                         }
1224                 }
1225                 /* append remaining agent keys */
1226                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1227                         TAILQ_REMOVE(&agent, id, next);
1228                         TAILQ_INSERT_TAIL(preferred, id, next);
1229                 }
1230                 authctxt->agent = ac;
1231         }
1232         /* append remaining keys from the config file */
1233         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1234                 TAILQ_REMOVE(&files, id, next);
1235                 TAILQ_INSERT_TAIL(preferred, id, next);
1236         }
1237         TAILQ_FOREACH(id, preferred, next) {
1238                 debug2("key: %s (%p),%s", id->filename, id->key,
1239                     id->userprovided ? " explicit" : "");
1240         }
1241 }
1242
1243 static void
1244 pubkey_cleanup(Authctxt *authctxt)
1245 {
1246         Identity *id;
1247
1248         if (authctxt->agent != NULL)
1249                 ssh_close_authentication_connection(authctxt->agent);
1250         for (id = TAILQ_FIRST(&authctxt->keys); id;
1251             id = TAILQ_FIRST(&authctxt->keys)) {
1252                 TAILQ_REMOVE(&authctxt->keys, id, next);
1253                 if (id->key)
1254                         key_free(id->key);
1255                 free(id->filename);
1256                 free(id);
1257         }
1258 }
1259
1260 int
1261 userauth_pubkey(Authctxt *authctxt)
1262 {
1263         Identity *id;
1264         int sent = 0;
1265
1266         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1267                 if (id->tried++)
1268                         return (0);
1269                 /* move key to the end of the queue */
1270                 TAILQ_REMOVE(&authctxt->keys, id, next);
1271                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1272                 /*
1273                  * send a test message if we have the public key. for
1274                  * encrypted keys we cannot do this and have to load the
1275                  * private key instead
1276                  */
1277                 if (id->key != NULL) {
1278                         if (key_type_plain(id->key->type) == KEY_RSA &&
1279                             (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1280                                 debug("Skipped %s key %s for RSA/MD5 server",
1281                                     key_type(id->key), id->filename);
1282                         } else if (id->key->type != KEY_RSA1) {
1283                                 debug("Offering %s public key: %s",
1284                                     key_type(id->key), id->filename);
1285                                 sent = send_pubkey_test(authctxt, id);
1286                         }
1287                 } else {
1288                         debug("Trying private key: %s", id->filename);
1289                         id->key = load_identity_file(id->filename,
1290                             id->userprovided);
1291                         if (id->key != NULL) {
1292                                 id->isprivate = 1;
1293                                 if (key_type_plain(id->key->type) == KEY_RSA &&
1294                                     (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1295                                         debug("Skipped %s key %s for RSA/MD5 "
1296                                             "server", key_type(id->key),
1297                                             id->filename);
1298                                 } else {
1299                                         sent = sign_and_send_pubkey(
1300                                             authctxt, id);
1301                                 }
1302                                 key_free(id->key);
1303                                 id->key = NULL;
1304                         }
1305                 }
1306                 if (sent)
1307                         return (sent);
1308         }
1309         return (0);
1310 }
1311
1312 /*
1313  * Send userauth request message specifying keyboard-interactive method.
1314  */
1315 int
1316 userauth_kbdint(Authctxt *authctxt)
1317 {
1318         static int attempt = 0;
1319
1320         if (attempt++ >= options.number_of_password_prompts)
1321                 return 0;
1322         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1323         if (attempt > 1 && !authctxt->info_req_seen) {
1324                 debug3("userauth_kbdint: disable: no info_req_seen");
1325                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1326                 return 0;
1327         }
1328
1329         debug2("userauth_kbdint");
1330         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1331         packet_put_cstring(authctxt->server_user);
1332         packet_put_cstring(authctxt->service);
1333         packet_put_cstring(authctxt->method->name);
1334         packet_put_cstring("");                                 /* lang */
1335         packet_put_cstring(options.kbd_interactive_devices ?
1336             options.kbd_interactive_devices : "");
1337         packet_send();
1338
1339         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1340         return 1;
1341 }
1342
1343 /*
1344  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1345  */
1346 void
1347 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1348 {
1349         Authctxt *authctxt = ctxt;
1350         char *name, *inst, *lang, *prompt, *response;
1351         u_int num_prompts, i;
1352         int echo = 0;
1353
1354         debug2("input_userauth_info_req");
1355
1356         if (authctxt == NULL)
1357                 fatal("input_userauth_info_req: no authentication context");
1358
1359         authctxt->info_req_seen = 1;
1360
1361         name = packet_get_string(NULL);
1362         inst = packet_get_string(NULL);
1363         lang = packet_get_string(NULL);
1364         if (strlen(name) > 0)
1365                 logit("%s", name);
1366         if (strlen(inst) > 0)
1367                 logit("%s", inst);
1368         free(name);
1369         free(inst);
1370         free(lang);
1371
1372         num_prompts = packet_get_int();
1373         /*
1374          * Begin to build info response packet based on prompts requested.
1375          * We commit to providing the correct number of responses, so if
1376          * further on we run into a problem that prevents this, we have to
1377          * be sure and clean this up and send a correct error response.
1378          */
1379         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1380         packet_put_int(num_prompts);
1381
1382         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1383         for (i = 0; i < num_prompts; i++) {
1384                 prompt = packet_get_string(NULL);
1385                 echo = packet_get_char();
1386
1387                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1388
1389                 packet_put_cstring(response);
1390                 explicit_bzero(response, strlen(response));
1391                 free(response);
1392                 free(prompt);
1393         }
1394         packet_check_eom(); /* done with parsing incoming message. */
1395
1396         packet_add_padding(64);
1397         packet_send();
1398 }
1399
1400 static int
1401 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1402     u_char *data, u_int datalen)
1403 {
1404         Buffer b;
1405         struct stat st;
1406         pid_t pid;
1407         int to[2], from[2], status, version = 2;
1408
1409         debug2("ssh_keysign called");
1410
1411         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1412                 error("ssh_keysign: not installed: %s", strerror(errno));
1413                 return -1;
1414         }
1415         if (fflush(stdout) != 0)
1416                 error("ssh_keysign: fflush: %s", strerror(errno));
1417         if (pipe(to) < 0) {
1418                 error("ssh_keysign: pipe: %s", strerror(errno));
1419                 return -1;
1420         }
1421         if (pipe(from) < 0) {
1422                 error("ssh_keysign: pipe: %s", strerror(errno));
1423                 return -1;
1424         }
1425         if ((pid = fork()) < 0) {
1426                 error("ssh_keysign: fork: %s", strerror(errno));
1427                 return -1;
1428         }
1429         if (pid == 0) {
1430                 /* keep the socket on exec */
1431                 fcntl(packet_get_connection_in(), F_SETFD, 0);
1432                 permanently_drop_suid(getuid());
1433                 close(from[0]);
1434                 if (dup2(from[1], STDOUT_FILENO) < 0)
1435                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1436                 close(to[1]);
1437                 if (dup2(to[0], STDIN_FILENO) < 0)
1438                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1439                 close(from[1]);
1440                 close(to[0]);
1441                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1442                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1443                     strerror(errno));
1444         }
1445         close(from[1]);
1446         close(to[0]);
1447
1448         buffer_init(&b);
1449         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1450         buffer_put_string(&b, data, datalen);
1451         if (ssh_msg_send(to[1], version, &b) == -1)
1452                 fatal("ssh_keysign: couldn't send request");
1453
1454         if (ssh_msg_recv(from[0], &b) < 0) {
1455                 error("ssh_keysign: no reply");
1456                 buffer_free(&b);
1457                 return -1;
1458         }
1459         close(from[0]);
1460         close(to[1]);
1461
1462         while (waitpid(pid, &status, 0) < 0)
1463                 if (errno != EINTR)
1464                         break;
1465
1466         if (buffer_get_char(&b) != version) {
1467                 error("ssh_keysign: bad version");
1468                 buffer_free(&b);
1469                 return -1;
1470         }
1471         *sigp = buffer_get_string(&b, lenp);
1472         buffer_free(&b);
1473
1474         return 0;
1475 }
1476
1477 int
1478 userauth_hostbased(Authctxt *authctxt)
1479 {
1480         Key *private = NULL;
1481         Sensitive *sensitive = authctxt->sensitive;
1482         Buffer b;
1483         u_char *signature, *blob;
1484         char *chost, *pkalg, *p;
1485         const char *service;
1486         u_int blen, slen;
1487         int ok, i, found = 0;
1488
1489         /* check for a useful key */
1490         for (i = 0; i < sensitive->nkeys; i++) {
1491                 private = sensitive->keys[i];
1492                 if (private && private->type != KEY_RSA1) {
1493                         found = 1;
1494                         /* we take and free the key */
1495                         sensitive->keys[i] = NULL;
1496                         break;
1497                 }
1498         }
1499         if (!found) {
1500                 debug("No more client hostkeys for hostbased authentication.");
1501                 return 0;
1502         }
1503         if (key_to_blob(private, &blob, &blen) == 0) {
1504                 key_free(private);
1505                 return 0;
1506         }
1507         /* figure out a name for the client host */
1508         p = get_local_name(packet_get_connection_in());
1509         if (p == NULL) {
1510                 error("userauth_hostbased: cannot get local ipaddr/name");
1511                 key_free(private);
1512                 free(blob);
1513                 return 0;
1514         }
1515         xasprintf(&chost, "%s.", p);
1516         debug2("userauth_hostbased: chost %s", chost);
1517         free(p);
1518
1519         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1520             authctxt->service;
1521         pkalg = xstrdup(key_ssh_name(private));
1522         buffer_init(&b);
1523         /* construct data */
1524         buffer_put_string(&b, session_id2, session_id2_len);
1525         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1526         buffer_put_cstring(&b, authctxt->server_user);
1527         buffer_put_cstring(&b, service);
1528         buffer_put_cstring(&b, authctxt->method->name);
1529         buffer_put_cstring(&b, pkalg);
1530         buffer_put_string(&b, blob, blen);
1531         buffer_put_cstring(&b, chost);
1532         buffer_put_cstring(&b, authctxt->local_user);
1533 #ifdef DEBUG_PK
1534         buffer_dump(&b);
1535 #endif
1536         if (sensitive->external_keysign)
1537                 ok = ssh_keysign(private, &signature, &slen,
1538                     buffer_ptr(&b), buffer_len(&b));
1539         else
1540                 ok = key_sign(private, &signature, &slen,
1541                     buffer_ptr(&b), buffer_len(&b));
1542         key_free(private);
1543         buffer_free(&b);
1544         if (ok != 0) {
1545                 error("key_sign failed");
1546                 free(chost);
1547                 free(pkalg);
1548                 free(blob);
1549                 return 0;
1550         }
1551         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1552         packet_put_cstring(authctxt->server_user);
1553         packet_put_cstring(authctxt->service);
1554         packet_put_cstring(authctxt->method->name);
1555         packet_put_cstring(pkalg);
1556         packet_put_string(blob, blen);
1557         packet_put_cstring(chost);
1558         packet_put_cstring(authctxt->local_user);
1559         packet_put_string(signature, slen);
1560         explicit_bzero(signature, slen);
1561         free(signature);
1562         free(chost);
1563         free(pkalg);
1564         free(blob);
1565
1566         packet_send();
1567         return 1;
1568 }
1569
1570 /* find auth method */
1571
1572 /*
1573  * given auth method name, if configurable options permit this method fill
1574  * in auth_ident field and return true, otherwise return false.
1575  */
1576 static int
1577 authmethod_is_enabled(Authmethod *method)
1578 {
1579         if (method == NULL)
1580                 return 0;
1581         /* return false if options indicate this method is disabled */
1582         if  (method->enabled == NULL || *method->enabled == 0)
1583                 return 0;
1584         /* return false if batch mode is enabled but method needs interactive mode */
1585         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1586                 return 0;
1587         return 1;
1588 }
1589
1590 static Authmethod *
1591 authmethod_lookup(const char *name)
1592 {
1593         Authmethod *method = NULL;
1594         if (name != NULL)
1595                 for (method = authmethods; method->name != NULL; method++)
1596                         if (strcmp(name, method->name) == 0)
1597                                 return method;
1598         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1599         return NULL;
1600 }
1601
1602 /* XXX internal state */
1603 static Authmethod *current = NULL;
1604 static char *supported = NULL;
1605 static char *preferred = NULL;
1606
1607 /*
1608  * Given the authentication method list sent by the server, return the
1609  * next method we should try.  If the server initially sends a nil list,
1610  * use a built-in default list.
1611  */
1612 static Authmethod *
1613 authmethod_get(char *authlist)
1614 {
1615         char *name = NULL;
1616         u_int next;
1617
1618         /* Use a suitable default if we're passed a nil list.  */
1619         if (authlist == NULL || strlen(authlist) == 0)
1620                 authlist = options.preferred_authentications;
1621
1622         if (supported == NULL || strcmp(authlist, supported) != 0) {
1623                 debug3("start over, passed a different list %s", authlist);
1624                 free(supported);
1625                 supported = xstrdup(authlist);
1626                 preferred = options.preferred_authentications;
1627                 debug3("preferred %s", preferred);
1628                 current = NULL;
1629         } else if (current != NULL && authmethod_is_enabled(current))
1630                 return current;
1631
1632         for (;;) {
1633                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1634                         debug("No more authentication methods to try.");
1635                         current = NULL;
1636                         return NULL;
1637                 }
1638                 preferred += next;
1639                 debug3("authmethod_lookup %s", name);
1640                 debug3("remaining preferred: %s", preferred);
1641                 if ((current = authmethod_lookup(name)) != NULL &&
1642                     authmethod_is_enabled(current)) {
1643                         debug3("authmethod_is_enabled %s", name);
1644                         debug("Next authentication method: %s", name);
1645                         free(name);
1646                         return current;
1647                 }
1648                 free(name);
1649         }
1650 }
1651
1652 static char *
1653 authmethods_get(void)
1654 {
1655         Authmethod *method = NULL;
1656         Buffer b;
1657         char *list;
1658
1659         buffer_init(&b);
1660         for (method = authmethods; method->name != NULL; method++) {
1661                 if (authmethod_is_enabled(method)) {
1662                         if (buffer_len(&b) > 0)
1663                                 buffer_append(&b, ",", 1);
1664                         buffer_append(&b, method->name, strlen(method->name));
1665                 }
1666         }
1667         buffer_append(&b, "\0", 1);
1668         list = xstrdup(buffer_ptr(&b));
1669         buffer_free(&b);
1670         return list;
1671 }
1672