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 __RCSID("$FreeBSD$");
  30
  31 #include <sys/types.h>
  32 #include <sys/socket.h>
  33 #include <sys/wait.h>
  34 #include <sys/stat.h>
  35
  36 #include <errno.h>
  37 #include <fcntl.h>
  38 #include <netdb.h>
  39 #include <pwd.h>
  40 #include <signal.h>
  41 #include <stdarg.h>
  42 #include <stdio.h>
  43 #include <string.h>
  44 #include <unistd.h>
  45 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS)
  46 #include <vis.h>
  47 #endif
  48
  49 #include "openbsd-compat/sys-queue.h"
  50
  51 #include "xmalloc.h"
  52 #include "ssh.h"
  53 #include "ssh2.h"
  54 #include "buffer.h"
  55 #include "packet.h"
  56 #include "compat.h"
  57 #include "cipher.h"
  58 #include "key.h"
  59 #include "kex.h"
  60 #include "myproposal.h"
  61 #include "sshconnect.h"
  62 #include "authfile.h"
  63 #include "dh.h"
  64 #include "authfd.h"
  65 #include "log.h"
  66 #include "readconf.h"
  67 #include "misc.h"
  68 #include "match.h"
  69 #include "dispatch.h"
  70 #include "canohost.h"
  71 #include "msg.h"
  72 #include "pathnames.h"
  73 #include "uidswap.h"
  74 #include "hostfile.h"
  75
  76 #ifdef GSSAPI
  77 #include "ssh-gss.h"
  78 #endif
  79
  80 /* import */
  81 extern char *client_version_string;
  82 extern char *server_version_string;
  83 extern Options options;
  84 #ifdef  NONE_CIPHER_ENABLED
  85 extern Kex *xxx_kex;
  86
  87 /*
  88  * tty_flag is set in ssh.c so we can use it here.  If set then prevent
  89  * the switch to the null cipher.
  90  */
  91
  92 extern int tty_flag;
  93 #endif
  94
  95 /*
  96  * SSH2 key exchange
  97  */
  98
  99 u_char *session_id2 = NULL;
 100 u_int session_id2_len = 0;
 101
 102 char *xxx_host;
 103 struct sockaddr *xxx_hostaddr;
 104
 105 Kex *xxx_kex = NULL;
 106
 107 static int
 108 verify_host_key_callback(Key *hostkey)
 109 {
 110         if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
 111                 fatal("Host key verification failed.");
 112         return 0;
 113 }
 114
 115 static char *
 116 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
 117 {
 118         char *oavail, *avail, *first, *last, *alg, *hostname, *ret;
 119         size_t maxlen;
 120         struct hostkeys *hostkeys;
 121         int ktype;
 122         u_int i;
 123
 124         /* Find all hostkeys for this hostname */
 125         get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
 126         hostkeys = init_hostkeys();
 127         for (i = 0; i < options.num_user_hostfiles; i++)
 128                 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]);
 129         for (i = 0; i < options.num_system_hostfiles; i++)
 130                 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]);
 131
 132         oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG);
 133         maxlen = strlen(avail) + 1;
 134         first = xmalloc(maxlen);
 135         last = xmalloc(maxlen);
 136         *first = *last = '\0';
 137
 138 #define ALG_APPEND(to, from) \
 139         do { \
 140                 if (*to != '\0') \
 141                         strlcat(to, ",", maxlen); \
 142                 strlcat(to, from, maxlen); \
 143         } while (0)
 144
 145         while ((alg = strsep(&avail, ",")) && *alg != '\0') {
 146                 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC)
 147                         fatal("%s: unknown alg %s", __func__, alg);
 148                 if (lookup_key_in_hostkeys_by_type(hostkeys,
 149                     key_type_plain(ktype), NULL))
 150                         ALG_APPEND(first, alg);
 151                 else
 152                         ALG_APPEND(last, alg);
 153         }
 154 #undef ALG_APPEND
 155         xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last);
 156         if (*first != '\0')
 157                 debug3("%s: prefer hostkeyalgs: %s", __func__, first);
 158
 159         free(first);
 160         free(last);
 161         free(hostname);
 162         free(oavail);
 163         free_hostkeys(hostkeys);
 164
 165         return ret;
 166 }
 167
 168 void
 169 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
 170 {
 171         Kex *kex;
 172
 173         xxx_host = host;
 174         xxx_hostaddr = hostaddr;
 175
 176         if (options.ciphers == (char *)-1) {
 177                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 178                 options.ciphers = NULL;
 179         }
 180         if (options.ciphers != NULL) {
 181                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 182                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 183         }
 184         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 185             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 186         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 187             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 188         if (options.compression) {
 189                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 190                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 191         } else {
 192                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 193                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 194         }
 195         if (options.macs != NULL) {
 196                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 197                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 198         }
 199         if (options.hostkeyalgorithms != NULL)
 200                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 201                     compat_pkalg_proposal(options.hostkeyalgorithms);
 202         else {
 203                 /* Prefer algorithms that we already have keys for */
 204                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 205                     compat_pkalg_proposal(
 206                     order_hostkeyalgs(host, hostaddr, port));
 207         }
 208         if (options.kex_algorithms != NULL)
 209                 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
 210         myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
 211             myproposal[PROPOSAL_KEX_ALGS]);
 212
 213         if (options.rekey_limit || options.rekey_interval)
 214                 packet_set_rekey_limits((u_int32_t)options.rekey_limit,
 215                     (time_t)options.rekey_interval);
 216
 217         /* start key exchange */
 218         kex = kex_setup(myproposal);
 219         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 220         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 221         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 222         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 223         kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
 224         kex->kex[KEX_C25519_SHA256] = kexc25519_client;
 225         kex->client_version_string=client_version_string;
 226         kex->server_version_string=server_version_string;
 227         kex->verify_host_key=&verify_host_key_callback;
 228
 229         xxx_kex = kex;
 230
 231         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 232
 233         if (options.use_roaming && !kex->roaming) {
 234                 debug("Roaming not allowed by server");
 235                 options.use_roaming = 0;
 236         }
 237
 238         session_id2 = kex->session_id;
 239         session_id2_len = kex->session_id_len;
 240
 241 #ifdef DEBUG_KEXDH
 242         /* send 1st encrypted/maced/compressed message */
 243         packet_start(SSH2_MSG_IGNORE);
 244         packet_put_cstring("markus");
 245         packet_send();
 246         packet_write_wait();
 247 #endif
 248 }
 249
 250 /*
 251  * Authenticate user
 252  */
 253
 254 typedef struct Authctxt Authctxt;
 255 typedef struct Authmethod Authmethod;
 256 typedef struct identity Identity;
 257 typedef struct idlist Idlist;
 258
 259 struct identity {
 260         TAILQ_ENTRY(identity) next;
 261         AuthenticationConnection *ac;   /* set if agent supports key */
 262         Key     *key;                   /* public/private key */
 263         char    *filename;              /* comment for agent-only keys */
 264         int     tried;
 265         int     isprivate;              /* key points to the private key */
 266         int     userprovided;
 267 };
 268 TAILQ_HEAD(idlist, identity);
 269
 270 struct Authctxt {
 271         const char *server_user;
 272         const char *local_user;
 273         const char *host;
 274         const char *service;
 275         Authmethod *method;
 276         sig_atomic_t success;
 277         char *authlist;
 278         /* pubkey */
 279         Idlist keys;
 280         AuthenticationConnection *agent;
 281         /* hostbased */
 282         Sensitive *sensitive;
 283         /* kbd-interactive */
 284         int info_req_seen;
 285         /* generic */
 286         void *methoddata;
 287 };
 288 struct Authmethod {
 289         char    *name;          /* string to compare against server's list */
 290         int     (*userauth)(Authctxt *authctxt);
 291         void    (*cleanup)(Authctxt *authctxt);
 292         int     *enabled;       /* flag in option struct that enables method */
 293         int     *batch_flag;    /* flag in option struct that disables method */
 294 };
 295
 296 void    input_userauth_success(int, u_int32_t, void *);
 297 void    input_userauth_success_unexpected(int, u_int32_t, void *);
 298 void    input_userauth_failure(int, u_int32_t, void *);
 299 void    input_userauth_banner(int, u_int32_t, void *);
 300 void    input_userauth_error(int, u_int32_t, void *);
 301 void    input_userauth_info_req(int, u_int32_t, void *);
 302 void    input_userauth_pk_ok(int, u_int32_t, void *);
 303 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 304
 305 int     userauth_none(Authctxt *);
 306 int     userauth_pubkey(Authctxt *);
 307 int     userauth_passwd(Authctxt *);
 308 int     userauth_kbdint(Authctxt *);
 309 int     userauth_hostbased(Authctxt *);
 310
 311 #ifdef GSSAPI
 312 int     userauth_gssapi(Authctxt *authctxt);
 313 void    input_gssapi_response(int type, u_int32_t, void *);
 314 void    input_gssapi_token(int type, u_int32_t, void *);
 315 void    input_gssapi_hash(int type, u_int32_t, void *);
 316 void    input_gssapi_error(int, u_int32_t, void *);
 317 void    input_gssapi_errtok(int, u_int32_t, void *);
 318 #endif
 319
 320 void    userauth(Authctxt *, char *);
 321
 322 static int sign_and_send_pubkey(Authctxt *, Identity *);
 323 static void pubkey_prepare(Authctxt *);
 324 static void pubkey_cleanup(Authctxt *);
 325 static Key *load_identity_file(char *, int);
 326
 327 static Authmethod *authmethod_get(char *authlist);
 328 static Authmethod *authmethod_lookup(const char *name);
 329 static char *authmethods_get(void);
 330
 331 Authmethod authmethods[] = {
 332 #ifdef GSSAPI
 333         {"gssapi-with-mic",
 334                 userauth_gssapi,
 335                 NULL,
 336                 &options.gss_authentication,
 337                 NULL},
 338 #endif
 339         {"hostbased",
 340                 userauth_hostbased,
 341                 NULL,
 342                 &options.hostbased_authentication,
 343                 NULL},
 344         {"publickey",
 345                 userauth_pubkey,
 346                 NULL,
 347                 &options.pubkey_authentication,
 348                 NULL},
 349         {"keyboard-interactive",
 350                 userauth_kbdint,
 351                 NULL,
 352                 &options.kbd_interactive_authentication,
 353                 &options.batch_mode},
 354         {"password",
 355                 userauth_passwd,
 356                 NULL,
 357                 &options.password_authentication,
 358                 &options.batch_mode},
 359         {"none",
 360                 userauth_none,
 361                 NULL,
 362                 NULL,
 363                 NULL},
 364         {NULL, NULL, NULL, NULL, NULL}
 365 };
 366
 367 void
 368 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 369     Sensitive *sensitive)
 370 {
 371         Authctxt authctxt;
 372         int type;
 373
 374         if (options.challenge_response_authentication)
 375                 options.kbd_interactive_authentication = 1;
 376
 377         packet_start(SSH2_MSG_SERVICE_REQUEST);
 378         packet_put_cstring("ssh-userauth");
 379         packet_send();
 380         debug("SSH2_MSG_SERVICE_REQUEST sent");
 381         packet_write_wait();
 382         type = packet_read();
 383         if (type != SSH2_MSG_SERVICE_ACCEPT)
 384                 fatal("Server denied authentication request: %d", type);
 385         if (packet_remaining() > 0) {
 386                 char *reply = packet_get_string(NULL);
 387                 debug2("service_accept: %s", reply);
 388                 free(reply);
 389         } else {
 390                 debug2("buggy server: service_accept w/o service");
 391         }
 392         packet_check_eom();
 393         debug("SSH2_MSG_SERVICE_ACCEPT received");
 394
 395         if (options.preferred_authentications == NULL)
 396                 options.preferred_authentications = authmethods_get();
 397
 398         /* setup authentication context */
 399         memset(&authctxt, 0, sizeof(authctxt));
 400         pubkey_prepare(&authctxt);
 401         authctxt.server_user = server_user;
 402         authctxt.local_user = local_user;
 403         authctxt.host = host;
 404         authctxt.service = "ssh-connection";            /* service name */
 405         authctxt.success = 0;
 406         authctxt.method = authmethod_lookup("none");
 407         authctxt.authlist = NULL;
 408         authctxt.methoddata = NULL;
 409         authctxt.sensitive = sensitive;
 410         authctxt.info_req_seen = 0;
 411         if (authctxt.method == NULL)
 412                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 413
 414         /* initial userauth request */
 415         userauth_none(&authctxt);
 416
 417         dispatch_init(&input_userauth_error);
 418         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 419         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 420         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 421         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 422
 423         pubkey_cleanup(&authctxt);
 424         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 425
 426 #ifdef  NONE_CIPHER_ENABLED
 427         /*
 428          * If the user explicitly requests to use the none cipher enable it
 429          * post authentication and only if the right conditions are met: both
 430          * of the NONE switches must be true and there must be no tty allocated.
 431          */
 432         if (options.none_switch == 1 && options.none_enabled == 1) {
 433                 if (!tty_flag) {
 434                         debug("Requesting none cipher re-keying...");
 435                         myproposal[PROPOSAL_ENC_ALGS_STOC] = "none";
 436                         myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none";
 437                         kex_prop2buf(&xxx_kex->my, myproposal);
 438                         packet_request_rekeying();
 439                         fprintf(stderr, "WARNING: enabled NONE cipher\n");
 440                 } else {
 441                         /* Requested NONE cipher on an interactive session. */
 442                         debug("Cannot switch to NONE cipher with tty "
 443                             "allocated");
 444                         fprintf(stderr, "NONE cipher switch disabled given "
 445                             "a TTY is allocated\n");
 446                 }
 447         }
 448 #endif
 449         debug("Authentication succeeded (%s).", authctxt.method->name);
 450 }
 451
 452 void
 453 userauth(Authctxt *authctxt, char *authlist)
 454 {
 455         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 456                 authctxt->method->cleanup(authctxt);
 457
 458         free(authctxt->methoddata);
 459         authctxt->methoddata = NULL;
 460         if (authlist == NULL) {
 461                 authlist = authctxt->authlist;
 462         } else {
 463                 free(authctxt->authlist);
 464                 authctxt->authlist = authlist;
 465         }
 466         for (;;) {
 467                 Authmethod *method = authmethod_get(authlist);
 468                 if (method == NULL)
 469                         fatal("Permission denied (%s).", authlist);
 470                 authctxt->method = method;
 471
 472                 /* reset the per method handler */
 473                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 474                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 475
 476                 /* and try new method */
 477                 if (method->userauth(authctxt) != 0) {
 478                         debug2("we sent a %s packet, wait for reply", method->name);
 479                         break;
 480                 } else {
 481                         debug2("we did not send a packet, disable method");
 482                         method->enabled = NULL;
 483                 }
 484         }
 485 }
 486
 487 /* ARGSUSED */
 488 void
 489 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 490 {
 491         fatal("input_userauth_error: bad message during authentication: "
 492             "type %d", type);
 493 }
 494
 495 /* ARGSUSED */
 496 void
 497 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 498 {
 499         char *msg, *raw, *lang;
 500         u_int len;
 501
 502         debug3("input_userauth_banner");
 503         raw = packet_get_string(&len);
 504         lang = packet_get_string(NULL);
 505         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
 506                 if (len > 65536)
 507                         len = 65536;
 508                 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
 509                 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH);
 510                 fprintf(stderr, "%s", msg);
 511                 free(msg);
 512         }
 513         free(raw);
 514         free(lang);
 515 }
 516
 517 /* ARGSUSED */
 518 void
 519 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 520 {
 521         Authctxt *authctxt = ctxt;
 522
 523         if (authctxt == NULL)
 524                 fatal("input_userauth_success: no authentication context");
 525         free(authctxt->authlist);
 526         authctxt->authlist = NULL;
 527         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 528                 authctxt->method->cleanup(authctxt);
 529         free(authctxt->methoddata);
 530         authctxt->methoddata = NULL;
 531         authctxt->success = 1;                  /* break out */
 532 }
 533
 534 void
 535 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
 536 {
 537         Authctxt *authctxt = ctxt;
 538
 539         if (authctxt == NULL)
 540                 fatal("%s: no authentication context", __func__);
 541
 542         fatal("Unexpected authentication success during %s.",
 543             authctxt->method->name);
 544 }
 545
 546 /* ARGSUSED */
 547 void
 548 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 549 {
 550         Authctxt *authctxt = ctxt;
 551         char *authlist = NULL;
 552         int partial;
 553
 554         if (authctxt == NULL)
 555                 fatal("input_userauth_failure: no authentication context");
 556
 557         authlist = packet_get_string(NULL);
 558         partial = packet_get_char();
 559         packet_check_eom();
 560
 561         if (partial != 0) {
 562                 logit("Authenticated with partial success.");
 563                 /* reset state */
 564                 pubkey_cleanup(authctxt);
 565                 pubkey_prepare(authctxt);
 566         }
 567         debug("Authentications that can continue: %s", authlist);
 568
 569         userauth(authctxt, authlist);
 570 }
 571
 572 /* ARGSUSED */
 573 void
 574 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 575 {
 576         Authctxt *authctxt = ctxt;
 577         Key *key = NULL;
 578         Identity *id = NULL;
 579         Buffer b;
 580         int pktype, sent = 0;
 581         u_int alen, blen;
 582         char *pkalg, *fp;
 583         u_char *pkblob;
 584
 585         if (authctxt == NULL)
 586                 fatal("input_userauth_pk_ok: no authentication context");
 587         if (datafellows & SSH_BUG_PKOK) {
 588                 /* this is similar to SSH_BUG_PKAUTH */
 589                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 590                 pkblob = packet_get_string(&blen);
 591                 buffer_init(&b);
 592                 buffer_append(&b, pkblob, blen);
 593                 pkalg = buffer_get_string(&b, &alen);
 594                 buffer_free(&b);
 595         } else {
 596                 pkalg = packet_get_string(&alen);
 597                 pkblob = packet_get_string(&blen);
 598         }
 599         packet_check_eom();
 600
 601         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 602
 603         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 604                 debug("unknown pkalg %s", pkalg);
 605                 goto done;
 606         }
 607         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 608                 debug("no key from blob. pkalg %s", pkalg);
 609                 goto done;
 610         }
 611         if (key->type != pktype) {
 612                 error("input_userauth_pk_ok: type mismatch "
 613                     "for decoded key (received %d, expected %d)",
 614                     key->type, pktype);
 615                 goto done;
 616         }
 617         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 618         debug2("input_userauth_pk_ok: fp %s", fp);
 619         free(fp);
 620
 621         /*
 622          * search keys in the reverse order, because last candidate has been
 623          * moved to the end of the queue.  this also avoids confusion by
 624          * duplicate keys
 625          */
 626         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 627                 if (key_equal(key, id->key)) {
 628                         sent = sign_and_send_pubkey(authctxt, id);
 629                         break;
 630                 }
 631         }
 632 done:
 633         if (key != NULL)
 634                 key_free(key);
 635         free(pkalg);
 636         free(pkblob);
 637
 638         /* try another method if we did not send a packet */
 639         if (sent == 0)
 640                 userauth(authctxt, NULL);
 641 }
 642
 643 #ifdef GSSAPI
 644 int
 645 userauth_gssapi(Authctxt *authctxt)
 646 {
 647         Gssctxt *gssctxt = NULL;
 648         static gss_OID_set gss_supported = NULL;
 649         static u_int mech = 0;
 650         OM_uint32 min;
 651         int ok = 0;
 652
 653         /* Try one GSSAPI method at a time, rather than sending them all at
 654          * once. */
 655
 656         if (gss_supported == NULL)
 657                 gss_indicate_mechs(&min, &gss_supported);
 658
 659         /* Check to see if the mechanism is usable before we offer it */
 660         while (mech < gss_supported->count && !ok) {
 661                 /* My DER encoding requires length<128 */
 662                 if (gss_supported->elements[mech].length < 128 &&
 663                     ssh_gssapi_check_mechanism(&gssctxt,
 664                     &gss_supported->elements[mech], authctxt->host)) {
 665                         ok = 1; /* Mechanism works */
 666                 } else {
 667                         mech++;
 668                 }
 669         }
 670
 671         if (!ok)
 672                 return 0;
 673
 674         authctxt->methoddata=(void *)gssctxt;
 675
 676         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 677         packet_put_cstring(authctxt->server_user);
 678         packet_put_cstring(authctxt->service);
 679         packet_put_cstring(authctxt->method->name);
 680
 681         packet_put_int(1);
 682
 683         packet_put_int((gss_supported->elements[mech].length) + 2);
 684         packet_put_char(SSH_GSS_OIDTYPE);
 685         packet_put_char(gss_supported->elements[mech].length);
 686         packet_put_raw(gss_supported->elements[mech].elements,
 687             gss_supported->elements[mech].length);
 688
 689         packet_send();
 690
 691         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 692         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 693         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 694         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 695
 696         mech++; /* Move along to next candidate */
 697
 698         return 1;
 699 }
 700
 701 static OM_uint32
 702 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 703 {
 704         Authctxt *authctxt = ctxt;
 705         Gssctxt *gssctxt = authctxt->methoddata;
 706         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 707         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 708         gss_buffer_desc gssbuf;
 709         OM_uint32 status, ms, flags;
 710         Buffer b;
 711
 712         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 713             recv_tok, &send_tok, &flags);
 714
 715         if (send_tok.length > 0) {
 716                 if (GSS_ERROR(status))
 717                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 718                 else
 719                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 720
 721                 packet_put_string(send_tok.value, send_tok.length);
 722                 packet_send();
 723                 gss_release_buffer(&ms, &send_tok);
 724         }
 725
 726         if (status == GSS_S_COMPLETE) {
 727                 /* send either complete or MIC, depending on mechanism */
 728                 if (!(flags & GSS_C_INTEG_FLAG)) {
 729                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 730                         packet_send();
 731                 } else {
 732                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 733                             authctxt->service, "gssapi-with-mic");
 734
 735                         gssbuf.value = buffer_ptr(&b);
 736                         gssbuf.length = buffer_len(&b);
 737
 738                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 739
 740                         if (!GSS_ERROR(status)) {
 741                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 742                                 packet_put_string(mic.value, mic.length);
 743
 744                                 packet_send();
 745                         }
 746
 747                         buffer_free(&b);
 748                         gss_release_buffer(&ms, &mic);
 749                 }
 750         }
 751
 752         return status;
 753 }
 754
 755 /* ARGSUSED */
 756 void
 757 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 758 {
 759         Authctxt *authctxt = ctxt;
 760         Gssctxt *gssctxt;
 761         int oidlen;
 762         char *oidv;
 763
 764         if (authctxt == NULL)
 765                 fatal("input_gssapi_response: no authentication context");
 766         gssctxt = authctxt->methoddata;
 767
 768         /* Setup our OID */
 769         oidv = packet_get_string(&oidlen);
 770
 771         if (oidlen <= 2 ||
 772             oidv[0] != SSH_GSS_OIDTYPE ||
 773             oidv[1] != oidlen - 2) {
 774                 free(oidv);
 775                 debug("Badly encoded mechanism OID received");
 776                 userauth(authctxt, NULL);
 777                 return;
 778         }
 779
 780         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 781                 fatal("Server returned different OID than expected");
 782
 783         packet_check_eom();
 784
 785         free(oidv);
 786
 787         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 788                 /* Start again with next method on list */
 789                 debug("Trying to start again");
 790                 userauth(authctxt, NULL);
 791                 return;
 792         }
 793 }
 794
 795 /* ARGSUSED */
 796 void
 797 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 798 {
 799         Authctxt *authctxt = ctxt;
 800         gss_buffer_desc recv_tok;
 801         OM_uint32 status;
 802         u_int slen;
 803
 804         if (authctxt == NULL)
 805                 fatal("input_gssapi_response: no authentication context");
 806
 807         recv_tok.value = packet_get_string(&slen);
 808         recv_tok.length = slen; /* safe typecast */
 809
 810         packet_check_eom();
 811
 812         status = process_gssapi_token(ctxt, &recv_tok);
 813
 814         free(recv_tok.value);
 815
 816         if (GSS_ERROR(status)) {
 817                 /* Start again with the next method in the list */
 818                 userauth(authctxt, NULL);
 819                 return;
 820         }
 821 }
 822
 823 /* ARGSUSED */
 824 void
 825 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 826 {
 827         Authctxt *authctxt = ctxt;
 828         Gssctxt *gssctxt;
 829         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 830         gss_buffer_desc recv_tok;
 831         OM_uint32 ms;
 832         u_int len;
 833
 834         if (authctxt == NULL)
 835                 fatal("input_gssapi_response: no authentication context");
 836         gssctxt = authctxt->methoddata;
 837
 838         recv_tok.value = packet_get_string(&len);
 839         recv_tok.length = len;
 840
 841         packet_check_eom();
 842
 843         /* Stick it into GSSAPI and see what it says */
 844         (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 845             &recv_tok, &send_tok, NULL);
 846
 847         free(recv_tok.value);
 848         gss_release_buffer(&ms, &send_tok);
 849
 850         /* Server will be returning a failed packet after this one */
 851 }
 852
 853 /* ARGSUSED */
 854 void
 855 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 856 {
 857         char *msg;
 858         char *lang;
 859
 860         /* maj */(void)packet_get_int();
 861         /* min */(void)packet_get_int();
 862         msg=packet_get_string(NULL);
 863         lang=packet_get_string(NULL);
 864
 865         packet_check_eom();
 866
 867         debug("Server GSSAPI Error:\n%s", msg);
 868         free(msg);
 869         free(lang);
 870 }
 871 #endif /* GSSAPI */
 872
 873 int
 874 userauth_none(Authctxt *authctxt)
 875 {
 876         /* initial userauth request */
 877         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 878         packet_put_cstring(authctxt->server_user);
 879         packet_put_cstring(authctxt->service);
 880         packet_put_cstring(authctxt->method->name);
 881         packet_send();
 882         return 1;
 883 }
 884
 885 int
 886 userauth_passwd(Authctxt *authctxt)
 887 {
 888         static int attempt = 0;
 889         char prompt[150];
 890         char *password;
 891         const char *host = options.host_key_alias ?  options.host_key_alias :
 892             authctxt->host;
 893
 894         if (attempt++ >= options.number_of_password_prompts)
 895                 return 0;
 896
 897         if (attempt != 1)
 898                 error("Permission denied, please try again.");
 899
 900         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 901             authctxt->server_user, host);
 902         password = read_passphrase(prompt, 0);
 903         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 904         packet_put_cstring(authctxt->server_user);
 905         packet_put_cstring(authctxt->service);
 906         packet_put_cstring(authctxt->method->name);
 907         packet_put_char(0);
 908         packet_put_cstring(password);
 909         explicit_bzero(password, strlen(password));
 910         free(password);
 911         packet_add_padding(64);
 912         packet_send();
 913
 914         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 915             &input_userauth_passwd_changereq);
 916
 917         return 1;
 918 }
 919
 920 /*
 921  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 922  */
 923 /* ARGSUSED */
 924 void
 925 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 926 {
 927         Authctxt *authctxt = ctxt;
 928         char *info, *lang, *password = NULL, *retype = NULL;
 929         char prompt[150];
 930         const char *host = options.host_key_alias ? options.host_key_alias :
 931             authctxt->host;
 932
 933         debug2("input_userauth_passwd_changereq");
 934
 935         if (authctxt == NULL)
 936                 fatal("input_userauth_passwd_changereq: "
 937                     "no authentication context");
 938
 939         info = packet_get_string(NULL);
 940         lang = packet_get_string(NULL);
 941         if (strlen(info) > 0)
 942                 logit("%s", info);
 943         free(info);
 944         free(lang);
 945         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 946         packet_put_cstring(authctxt->server_user);
 947         packet_put_cstring(authctxt->service);
 948         packet_put_cstring(authctxt->method->name);
 949         packet_put_char(1);                     /* additional info */
 950         snprintf(prompt, sizeof(prompt),
 951             "Enter %.30s@%.128s's old password: ",
 952             authctxt->server_user, host);
 953         password = read_passphrase(prompt, 0);
 954         packet_put_cstring(password);
 955         explicit_bzero(password, strlen(password));
 956         free(password);
 957         password = NULL;
 958         while (password == NULL) {
 959                 snprintf(prompt, sizeof(prompt),
 960                     "Enter %.30s@%.128s's new password: ",
 961                     authctxt->server_user, host);
 962                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 963                 if (password == NULL) {
 964                         /* bail out */
 965                         return;
 966                 }
 967                 snprintf(prompt, sizeof(prompt),
 968                     "Retype %.30s@%.128s's new password: ",
 969                     authctxt->server_user, host);
 970                 retype = read_passphrase(prompt, 0);
 971                 if (strcmp(password, retype) != 0) {
 972                         explicit_bzero(password, strlen(password));
 973                         free(password);
 974                         logit("Mismatch; try again, EOF to quit.");
 975                         password = NULL;
 976                 }
 977                 explicit_bzero(retype, strlen(retype));
 978                 free(retype);
 979         }
 980         packet_put_cstring(password);
 981         explicit_bzero(password, strlen(password));
 982         free(password);
 983         packet_add_padding(64);
 984         packet_send();
 985
 986         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 987             &input_userauth_passwd_changereq);
 988 }
 989
 990 static int
 991 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
 992     u_char *data, u_int datalen)
 993 {
 994         Key *prv;
 995         int ret;
 996
 997         /* the agent supports this key */
 998         if (id->ac)
 999                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1000                     data, datalen));
1001         /*
1002          * we have already loaded the private key or
1003          * the private key is stored in external hardware
1004          */
1005         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1006                 return (key_sign(id->key, sigp, lenp, data, datalen));
1007         /* load the private key from the file */
1008         if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL)
1009                 return (-1);
1010         ret = key_sign(prv, sigp, lenp, data, datalen);
1011         key_free(prv);
1012         return (ret);
1013 }
1014
1015 static int
1016 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1017 {
1018         Buffer b;
1019         u_char *blob, *signature;
1020         u_int bloblen, slen;
1021         u_int skip = 0;
1022         int ret = -1;
1023         int have_sig = 1;
1024         char *fp;
1025
1026         fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
1027         debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp);
1028         free(fp);
1029
1030         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1031                 /* we cannot handle this key */
1032                 debug3("sign_and_send_pubkey: cannot handle key");
1033                 return 0;
1034         }
1035         /* data to be signed */
1036         buffer_init(&b);
1037         if (datafellows & SSH_OLD_SESSIONID) {
1038                 buffer_append(&b, session_id2, session_id2_len);
1039                 skip = session_id2_len;
1040         } else {
1041                 buffer_put_string(&b, session_id2, session_id2_len);
1042                 skip = buffer_len(&b);
1043         }
1044         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1045         buffer_put_cstring(&b, authctxt->server_user);
1046         buffer_put_cstring(&b,
1047             datafellows & SSH_BUG_PKSERVICE ?
1048             "ssh-userauth" :
1049             authctxt->service);
1050         if (datafellows & SSH_BUG_PKAUTH) {
1051                 buffer_put_char(&b, have_sig);
1052         } else {
1053                 buffer_put_cstring(&b, authctxt->method->name);
1054                 buffer_put_char(&b, have_sig);
1055                 buffer_put_cstring(&b, key_ssh_name(id->key));
1056         }
1057         buffer_put_string(&b, blob, bloblen);
1058
1059         /* generate signature */
1060         ret = identity_sign(id, &signature, &slen,
1061             buffer_ptr(&b), buffer_len(&b));
1062         if (ret == -1) {
1063                 free(blob);
1064                 buffer_free(&b);
1065                 return 0;
1066         }
1067 #ifdef DEBUG_PK
1068         buffer_dump(&b);
1069 #endif
1070         if (datafellows & SSH_BUG_PKSERVICE) {
1071                 buffer_clear(&b);
1072                 buffer_append(&b, session_id2, session_id2_len);
1073                 skip = session_id2_len;
1074                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1075                 buffer_put_cstring(&b, authctxt->server_user);
1076                 buffer_put_cstring(&b, authctxt->service);
1077                 buffer_put_cstring(&b, authctxt->method->name);
1078                 buffer_put_char(&b, have_sig);
1079                 if (!(datafellows & SSH_BUG_PKAUTH))
1080                         buffer_put_cstring(&b, key_ssh_name(id->key));
1081                 buffer_put_string(&b, blob, bloblen);
1082         }
1083         free(blob);
1084
1085         /* append signature */
1086         buffer_put_string(&b, signature, slen);
1087         free(signature);
1088
1089         /* skip session id and packet type */
1090         if (buffer_len(&b) < skip + 1)
1091                 fatal("userauth_pubkey: internal error");
1092         buffer_consume(&b, skip + 1);
1093
1094         /* put remaining data from buffer into packet */
1095         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1096         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1097         buffer_free(&b);
1098         packet_send();
1099
1100         return 1;
1101 }
1102
1103 static int
1104 send_pubkey_test(Authctxt *authctxt, Identity *id)
1105 {
1106         u_char *blob;
1107         u_int bloblen, have_sig = 0;
1108
1109         debug3("send_pubkey_test");
1110
1111         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1112                 /* we cannot handle this key */
1113                 debug3("send_pubkey_test: cannot handle key");
1114                 return 0;
1115         }
1116         /* register callback for USERAUTH_PK_OK message */
1117         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1118
1119         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1120         packet_put_cstring(authctxt->server_user);
1121         packet_put_cstring(authctxt->service);
1122         packet_put_cstring(authctxt->method->name);
1123         packet_put_char(have_sig);
1124         if (!(datafellows & SSH_BUG_PKAUTH))
1125                 packet_put_cstring(key_ssh_name(id->key));
1126         packet_put_string(blob, bloblen);
1127         free(blob);
1128         packet_send();
1129         return 1;
1130 }
1131
1132 static Key *
1133 load_identity_file(char *filename, int userprovided)
1134 {
1135         Key *private;
1136         char prompt[300], *passphrase;
1137         int perm_ok = 0, quit, i;
1138         struct stat st;
1139
1140         if (stat(filename, &st) < 0) {
1141                 (userprovided ? logit : debug3)("no such identity: %s: %s",
1142                     filename, strerror(errno));
1143                 return NULL;
1144         }
1145         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1146         if (!perm_ok) {
1147                 if (private != NULL)
1148                         key_free(private);
1149                 return NULL;
1150         }
1151         if (private == NULL) {
1152                 if (options.batch_mode)
1153                         return NULL;
1154                 snprintf(prompt, sizeof prompt,
1155                     "Enter passphrase for key '%.100s': ", filename);
1156                 for (i = 0; i < options.number_of_password_prompts; i++) {
1157                         passphrase = read_passphrase(prompt, 0);
1158                         if (strcmp(passphrase, "") != 0) {
1159                                 private = key_load_private_type(KEY_UNSPEC,
1160                                     filename, passphrase, NULL, NULL);
1161                                 quit = 0;
1162                         } else {
1163                                 debug2("no passphrase given, try next key");
1164                                 quit = 1;
1165                         }
1166                         explicit_bzero(passphrase, strlen(passphrase));
1167                         free(passphrase);
1168                         if (private != NULL || quit)
1169                                 break;
1170                         debug2("bad passphrase given, try again...");
1171                 }
1172         }
1173         return private;
1174 }
1175
1176 /*
1177  * try keys in the following order:
1178  *      1. agent keys that are found in the config file
1179  *      2. other agent keys
1180  *      3. keys that are only listed in the config file
1181  */
1182 static void
1183 pubkey_prepare(Authctxt *authctxt)
1184 {
1185         Identity *id, *id2, *tmp;
1186         Idlist agent, files, *preferred;
1187         Key *key;
1188         AuthenticationConnection *ac;
1189         char *comment;
1190         int i, found;
1191
1192         TAILQ_INIT(&agent);     /* keys from the agent */
1193         TAILQ_INIT(&files);     /* keys from the config file */
1194         preferred = &authctxt->keys;
1195         TAILQ_INIT(preferred);  /* preferred order of keys */
1196
1197         /* list of keys stored in the filesystem and PKCS#11 */
1198         for (i = 0; i < options.num_identity_files; i++) {
1199                 key = options.identity_keys[i];
1200                 if (key && key->type == KEY_RSA1)
1201                         continue;
1202                 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1203                         continue;
1204                 options.identity_keys[i] = NULL;
1205                 id = xcalloc(1, sizeof(*id));
1206                 id->key = key;
1207                 id->filename = xstrdup(options.identity_files[i]);
1208                 id->userprovided = options.identity_file_userprovided[i];
1209                 TAILQ_INSERT_TAIL(&files, id, next);
1210         }
1211         /* Prefer PKCS11 keys that are explicitly listed */
1212         TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1213                 if (id->key == NULL || (id->key->flags & KEY_FLAG_EXT) == 0)
1214                         continue;
1215                 found = 0;
1216                 TAILQ_FOREACH(id2, &files, next) {
1217                         if (id2->key == NULL ||
1218                             (id2->key->flags & KEY_FLAG_EXT) != 0)
1219                                 continue;
1220                         if (key_equal(id->key, id2->key)) {
1221                                 TAILQ_REMOVE(&files, id, next);
1222                                 TAILQ_INSERT_TAIL(preferred, id, next);
1223                                 found = 1;
1224                                 break;
1225                         }
1226                 }
1227                 /* If IdentitiesOnly set and key not found then don't use it */
1228                 if (!found && options.identities_only) {
1229                         TAILQ_REMOVE(&files, id, next);
1230                         explicit_bzero(id, sizeof(*id));
1231                         free(id);
1232                 }
1233         }
1234         /* list of keys supported by the agent */
1235         if ((ac = ssh_get_authentication_connection())) {
1236                 for (key = ssh_get_first_identity(ac, &comment, 2);
1237                     key != NULL;
1238                     key = ssh_get_next_identity(ac, &comment, 2)) {
1239                         found = 0;
1240                         TAILQ_FOREACH(id, &files, next) {
1241                                 /* agent keys from the config file are preferred */
1242                                 if (key_equal(key, id->key)) {
1243                                         key_free(key);
1244                                         free(comment);
1245                                         TAILQ_REMOVE(&files, id, next);
1246                                         TAILQ_INSERT_TAIL(preferred, id, next);
1247                                         id->ac = ac;
1248                                         found = 1;
1249                                         break;
1250                                 }
1251                         }
1252                         if (!found && !options.identities_only) {
1253                                 id = xcalloc(1, sizeof(*id));
1254                                 id->key = key;
1255                                 id->filename = comment;
1256                                 id->ac = ac;
1257                                 TAILQ_INSERT_TAIL(&agent, id, next);
1258                         }
1259                 }
1260                 /* append remaining agent keys */
1261                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1262                         TAILQ_REMOVE(&agent, id, next);
1263                         TAILQ_INSERT_TAIL(preferred, id, next);
1264                 }
1265                 authctxt->agent = ac;
1266         }
1267         /* append remaining keys from the config file */
1268         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1269                 TAILQ_REMOVE(&files, id, next);
1270                 TAILQ_INSERT_TAIL(preferred, id, next);
1271         }
1272         TAILQ_FOREACH(id, preferred, next) {
1273                 debug2("key: %s (%p),%s", id->filename, id->key,
1274                     id->userprovided ? " explicit" : "");
1275         }
1276 }
1277
1278 static void
1279 pubkey_cleanup(Authctxt *authctxt)
1280 {
1281         Identity *id;
1282
1283         if (authctxt->agent != NULL)
1284                 ssh_close_authentication_connection(authctxt->agent);
1285         for (id = TAILQ_FIRST(&authctxt->keys); id;
1286             id = TAILQ_FIRST(&authctxt->keys)) {
1287                 TAILQ_REMOVE(&authctxt->keys, id, next);
1288                 if (id->key)
1289                         key_free(id->key);
1290                 free(id->filename);
1291                 free(id);
1292         }
1293 }
1294
1295 int
1296 userauth_pubkey(Authctxt *authctxt)
1297 {
1298         Identity *id;
1299         int sent = 0;
1300
1301         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1302                 if (id->tried++)
1303                         return (0);
1304                 /* move key to the end of the queue */
1305                 TAILQ_REMOVE(&authctxt->keys, id, next);
1306                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1307                 /*
1308                  * send a test message if we have the public key. for
1309                  * encrypted keys we cannot do this and have to load the
1310                  * private key instead
1311                  */
1312                 if (id->key != NULL) {
1313                         if (key_type_plain(id->key->type) == KEY_RSA &&
1314                             (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1315                                 debug("Skipped %s key %s for RSA/MD5 server",
1316                                     key_type(id->key), id->filename);
1317                         } else if (id->key->type != KEY_RSA1) {
1318                                 debug("Offering %s public key: %s",
1319                                     key_type(id->key), id->filename);
1320                                 sent = send_pubkey_test(authctxt, id);
1321                         }
1322                 } else {
1323                         debug("Trying private key: %s", id->filename);
1324                         id->key = load_identity_file(id->filename,
1325                             id->userprovided);
1326                         if (id->key != NULL) {
1327                                 id->isprivate = 1;
1328                                 if (key_type_plain(id->key->type) == KEY_RSA &&
1329                                     (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1330                                         debug("Skipped %s key %s for RSA/MD5 "
1331                                             "server", key_type(id->key),
1332                                             id->filename);
1333                                 } else {
1334                                         sent = sign_and_send_pubkey(
1335                                             authctxt, id);
1336                                 }
1337                                 key_free(id->key);
1338                                 id->key = NULL;
1339                         }
1340                 }
1341                 if (sent)
1342                         return (sent);
1343         }
1344         return (0);
1345 }
1346
1347 /*
1348  * Send userauth request message specifying keyboard-interactive method.
1349  */
1350 int
1351 userauth_kbdint(Authctxt *authctxt)
1352 {
1353         static int attempt = 0;
1354
1355         if (attempt++ >= options.number_of_password_prompts)
1356                 return 0;
1357         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1358         if (attempt > 1 && !authctxt->info_req_seen) {
1359                 debug3("userauth_kbdint: disable: no info_req_seen");
1360                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1361                 return 0;
1362         }
1363
1364         debug2("userauth_kbdint");
1365         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1366         packet_put_cstring(authctxt->server_user);
1367         packet_put_cstring(authctxt->service);
1368         packet_put_cstring(authctxt->method->name);
1369         packet_put_cstring("");                                 /* lang */
1370         packet_put_cstring(options.kbd_interactive_devices ?
1371             options.kbd_interactive_devices : "");
1372         packet_send();
1373
1374         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1375         return 1;
1376 }
1377
1378 /*
1379  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1380  */
1381 void
1382 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1383 {
1384         Authctxt *authctxt = ctxt;
1385         char *name, *inst, *lang, *prompt, *response;
1386         u_int num_prompts, i;
1387         int echo = 0;
1388
1389         debug2("input_userauth_info_req");
1390
1391         if (authctxt == NULL)
1392                 fatal("input_userauth_info_req: no authentication context");
1393
1394         authctxt->info_req_seen = 1;
1395
1396         name = packet_get_string(NULL);
1397         inst = packet_get_string(NULL);
1398         lang = packet_get_string(NULL);
1399         if (strlen(name) > 0)
1400                 logit("%s", name);
1401         if (strlen(inst) > 0)
1402                 logit("%s", inst);
1403         free(name);
1404         free(inst);
1405         free(lang);
1406
1407         num_prompts = packet_get_int();
1408         /*
1409          * Begin to build info response packet based on prompts requested.
1410          * We commit to providing the correct number of responses, so if
1411          * further on we run into a problem that prevents this, we have to
1412          * be sure and clean this up and send a correct error response.
1413          */
1414         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1415         packet_put_int(num_prompts);
1416
1417         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1418         for (i = 0; i < num_prompts; i++) {
1419                 prompt = packet_get_string(NULL);
1420                 echo = packet_get_char();
1421
1422                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1423
1424                 packet_put_cstring(response);
1425                 explicit_bzero(response, strlen(response));
1426                 free(response);
1427                 free(prompt);
1428         }
1429         packet_check_eom(); /* done with parsing incoming message. */
1430
1431         packet_add_padding(64);
1432         packet_send();
1433 }
1434
1435 static int
1436 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1437     u_char *data, u_int datalen)
1438 {
1439         Buffer b;
1440         struct stat st;
1441         pid_t pid;
1442         int to[2], from[2], status, version = 2;
1443
1444         debug2("ssh_keysign called");
1445
1446         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1447                 error("ssh_keysign: not installed: %s", strerror(errno));
1448                 return -1;
1449         }
1450         if (fflush(stdout) != 0)
1451                 error("ssh_keysign: fflush: %s", strerror(errno));
1452         if (pipe(to) < 0) {
1453                 error("ssh_keysign: pipe: %s", strerror(errno));
1454                 return -1;
1455         }
1456         if (pipe(from) < 0) {
1457                 error("ssh_keysign: pipe: %s", strerror(errno));
1458                 return -1;
1459         }
1460         if ((pid = fork()) < 0) {
1461                 error("ssh_keysign: fork: %s", strerror(errno));
1462                 return -1;
1463         }
1464         if (pid == 0) {
1465                 /* keep the socket on exec */
1466                 fcntl(packet_get_connection_in(), F_SETFD, 0);
1467                 permanently_drop_suid(getuid());
1468                 close(from[0]);
1469                 if (dup2(from[1], STDOUT_FILENO) < 0)
1470                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1471                 close(to[1]);
1472                 if (dup2(to[0], STDIN_FILENO) < 0)
1473                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1474                 close(from[1]);
1475                 close(to[0]);
1476                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1477                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1478                     strerror(errno));
1479         }
1480         close(from[1]);
1481         close(to[0]);
1482
1483         buffer_init(&b);
1484         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1485         buffer_put_string(&b, data, datalen);
1486         if (ssh_msg_send(to[1], version, &b) == -1)
1487                 fatal("ssh_keysign: couldn't send request");
1488
1489         if (ssh_msg_recv(from[0], &b) < 0) {
1490                 error("ssh_keysign: no reply");
1491                 buffer_free(&b);
1492                 return -1;
1493         }
1494         close(from[0]);
1495         close(to[1]);
1496
1497         while (waitpid(pid, &status, 0) < 0)
1498                 if (errno != EINTR)
1499                         break;
1500
1501         if (buffer_get_char(&b) != version) {
1502                 error("ssh_keysign: bad version");
1503                 buffer_free(&b);
1504                 return -1;
1505         }
1506         *sigp = buffer_get_string(&b, lenp);
1507         buffer_free(&b);
1508
1509         return 0;
1510 }
1511
1512 int
1513 userauth_hostbased(Authctxt *authctxt)
1514 {
1515         Key *private = NULL;
1516         Sensitive *sensitive = authctxt->sensitive;
1517         Buffer b;
1518         u_char *signature, *blob;
1519         char *chost, *pkalg, *p;
1520         const char *service;
1521         u_int blen, slen;
1522         int ok, i, found = 0;
1523
1524         /* check for a useful key */
1525         for (i = 0; i < sensitive->nkeys; i++) {
1526                 private = sensitive->keys[i];
1527                 if (private && private->type != KEY_RSA1) {
1528                         found = 1;
1529                         /* we take and free the key */
1530                         sensitive->keys[i] = NULL;
1531                         break;
1532                 }
1533         }
1534         if (!found) {
1535                 debug("No more client hostkeys for hostbased authentication.");
1536                 return 0;
1537         }
1538         if (key_to_blob(private, &blob, &blen) == 0) {
1539                 key_free(private);
1540                 return 0;
1541         }
1542         /* figure out a name for the client host */
1543         p = get_local_name(packet_get_connection_in());
1544         if (p == NULL) {
1545                 error("userauth_hostbased: cannot get local ipaddr/name");
1546                 key_free(private);
1547                 free(blob);
1548                 return 0;
1549         }
1550         xasprintf(&chost, "%s.", p);
1551         debug2("userauth_hostbased: chost %s", chost);
1552         free(p);
1553
1554         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1555             authctxt->service;
1556         pkalg = xstrdup(key_ssh_name(private));
1557         buffer_init(&b);
1558         /* construct data */
1559         buffer_put_string(&b, session_id2, session_id2_len);
1560         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1561         buffer_put_cstring(&b, authctxt->server_user);
1562         buffer_put_cstring(&b, service);
1563         buffer_put_cstring(&b, authctxt->method->name);
1564         buffer_put_cstring(&b, pkalg);
1565         buffer_put_string(&b, blob, blen);
1566         buffer_put_cstring(&b, chost);
1567         buffer_put_cstring(&b, authctxt->local_user);
1568 #ifdef DEBUG_PK
1569         buffer_dump(&b);
1570 #endif
1571         if (sensitive->external_keysign)
1572                 ok = ssh_keysign(private, &signature, &slen,
1573                     buffer_ptr(&b), buffer_len(&b));
1574         else
1575                 ok = key_sign(private, &signature, &slen,
1576                     buffer_ptr(&b), buffer_len(&b));
1577         key_free(private);
1578         buffer_free(&b);
1579         if (ok != 0) {
1580                 error("key_sign failed");
1581                 free(chost);
1582                 free(pkalg);
1583                 free(blob);
1584                 return 0;
1585         }
1586         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1587         packet_put_cstring(authctxt->server_user);
1588         packet_put_cstring(authctxt->service);
1589         packet_put_cstring(authctxt->method->name);
1590         packet_put_cstring(pkalg);
1591         packet_put_string(blob, blen);
1592         packet_put_cstring(chost);
1593         packet_put_cstring(authctxt->local_user);
1594         packet_put_string(signature, slen);
1595         explicit_bzero(signature, slen);
1596         free(signature);
1597         free(chost);
1598         free(pkalg);
1599         free(blob);
1600
1601         packet_send();
1602         return 1;
1603 }
1604
1605 /* find auth method */
1606
1607 /*
1608  * given auth method name, if configurable options permit this method fill
1609  * in auth_ident field and return true, otherwise return false.
1610  */
1611 static int
1612 authmethod_is_enabled(Authmethod *method)
1613 {
1614         if (method == NULL)
1615                 return 0;
1616         /* return false if options indicate this method is disabled */
1617         if  (method->enabled == NULL || *method->enabled == 0)
1618                 return 0;
1619         /* return false if batch mode is enabled but method needs interactive mode */
1620         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1621                 return 0;
1622         return 1;
1623 }
1624
1625 static Authmethod *
1626 authmethod_lookup(const char *name)
1627 {
1628         Authmethod *method = NULL;
1629         if (name != NULL)
1630                 for (method = authmethods; method->name != NULL; method++)
1631                         if (strcmp(name, method->name) == 0)
1632                                 return method;
1633         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1634         return NULL;
1635 }
1636
1637 /* XXX internal state */
1638 static Authmethod *current = NULL;
1639 static char *supported = NULL;
1640 static char *preferred = NULL;
1641
1642 /*
1643  * Given the authentication method list sent by the server, return the
1644  * next method we should try.  If the server initially sends a nil list,
1645  * use a built-in default list.
1646  */
1647 static Authmethod *
1648 authmethod_get(char *authlist)
1649 {
1650         char *name = NULL;
1651         u_int next;
1652
1653         /* Use a suitable default if we're passed a nil list.  */
1654         if (authlist == NULL || strlen(authlist) == 0)
1655                 authlist = options.preferred_authentications;
1656
1657         if (supported == NULL || strcmp(authlist, supported) != 0) {
1658                 debug3("start over, passed a different list %s", authlist);
1659                 free(supported);
1660                 supported = xstrdup(authlist);
1661                 preferred = options.preferred_authentications;
1662                 debug3("preferred %s", preferred);
1663                 current = NULL;
1664         } else if (current != NULL && authmethod_is_enabled(current))
1665                 return current;
1666
1667         for (;;) {
1668                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1669                         debug("No more authentication methods to try.");
1670                         current = NULL;
1671                         return NULL;
1672                 }
1673                 preferred += next;
1674                 debug3("authmethod_lookup %s", name);
1675                 debug3("remaining preferred: %s", preferred);
1676                 if ((current = authmethod_lookup(name)) != NULL &&
1677                     authmethod_is_enabled(current)) {
1678                         debug3("authmethod_is_enabled %s", name);
1679                         debug("Next authentication method: %s", name);
1680                         free(name);
1681                         return current;
1682                 }
1683                 free(name);
1684         }
1685 }
1686
1687 static char *
1688 authmethods_get(void)
1689 {
1690         Authmethod *method = NULL;
1691         Buffer b;
1692         char *list;
1693
1694         buffer_init(&b);
1695         for (method = authmethods; method->name != NULL; method++) {
1696                 if (authmethod_is_enabled(method)) {
1697                         if (buffer_len(&b) > 0)
1698                                 buffer_append(&b, ",", 1);
1699                         buffer_append(&b, method->name, strlen(method->name));
1700                 }
1701         }
1702         buffer_append(&b, "\0", 1);
1703         list = xstrdup(buffer_ptr(&b));
1704         buffer_free(&b);
1705         return list;
1706 }
1707