sshconnect2.c

   1 /* $OpenBSD: sshconnect2.c,v 1.173 2009/10/24 11:13:54 andreas 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 <netdb.h>
  36 #include <pwd.h>
  37 #include <signal.h>
  38 #include <stdarg.h>
  39 #include <stdio.h>
  40 #include <string.h>
  41 #include <unistd.h>
  42 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H)
  43 #include <vis.h>
  44 #endif
  45
  46 #include "openbsd-compat/sys-queue.h"
  47
  48 #include "xmalloc.h"
  49 #include "ssh.h"
  50 #include "ssh2.h"
  51 #include "buffer.h"
  52 #include "packet.h"
  53 #include "compat.h"
  54 #include "cipher.h"
  55 #include "key.h"
  56 #include "kex.h"
  57 #include "myproposal.h"
  58 #include "sshconnect.h"
  59 #include "authfile.h"
  60 #include "dh.h"
  61 #include "authfd.h"
  62 #include "log.h"
  63 #include "readconf.h"
  64 #include "misc.h"
  65 #include "match.h"
  66 #include "dispatch.h"
  67 #include "canohost.h"
  68 #include "msg.h"
  69 #include "pathnames.h"
  70 #include "uidswap.h"
  71 #include "schnorr.h"
  72 #include "jpake.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 void
 104 ssh_kex2(char *host, struct sockaddr *hostaddr)
 105 {
 106         Kex *kex;
 107
 108         xxx_host = host;
 109         xxx_hostaddr = hostaddr;
 110
 111         if (options.ciphers == (char *)-1) {
 112                 logit("No valid ciphers for protocol version 2 given, using defaults.");
 113                 options.ciphers = NULL;
 114         }
 115         if (options.ciphers != NULL) {
 116                 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 117                 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
 118         }
 119         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
 120             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
 121         myproposal[PROPOSAL_ENC_ALGS_STOC] =
 122             compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
 123         if (options.compression) {
 124                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 125                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
 126         } else {
 127                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
 128                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
 129         }
 130         if (options.macs != NULL) {
 131                 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
 132                 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 133         }
 134         if (options.hostkeyalgorithms != NULL)
 135                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
 136                     options.hostkeyalgorithms;
 137
 138         if (options.rekey_limit)
 139                 packet_set_rekey_limit((u_int32_t)options.rekey_limit);
 140
 141         /* start key exchange */
 142         kex = kex_setup(myproposal);
 143         kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
 144         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 145         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 146         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
 147         kex->client_version_string=client_version_string;
 148         kex->server_version_string=server_version_string;
 149         kex->verify_host_key=&verify_host_key_callback;
 150
 151         xxx_kex = kex;
 152
 153         dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 154
 155         if (options.use_roaming && !kex->roaming) {
 156                 debug("Roaming not allowed by server");
 157                 options.use_roaming = 0;
 158         }
 159
 160         session_id2 = kex->session_id;
 161         session_id2_len = kex->session_id_len;
 162
 163 #ifdef DEBUG_KEXDH
 164         /* send 1st encrypted/maced/compressed message */
 165         packet_start(SSH2_MSG_IGNORE);
 166         packet_put_cstring("markus");
 167         packet_send();
 168         packet_write_wait();
 169 #endif
 170 }
 171
 172 /*
 173  * Authenticate user
 174  */
 175
 176 typedef struct Authctxt Authctxt;
 177 typedef struct Authmethod Authmethod;
 178 typedef struct identity Identity;
 179 typedef struct idlist Idlist;
 180
 181 struct identity {
 182         TAILQ_ENTRY(identity) next;
 183         AuthenticationConnection *ac;   /* set if agent supports key */
 184         Key     *key;                   /* public/private key */
 185         char    *filename;              /* comment for agent-only keys */
 186         int     tried;
 187         int     isprivate;              /* key points to the private key */
 188 };
 189 TAILQ_HEAD(idlist, identity);
 190
 191 struct Authctxt {
 192         const char *server_user;
 193         const char *local_user;
 194         const char *host;
 195         const char *service;
 196         Authmethod *method;
 197         int success;
 198         char *authlist;
 199         /* pubkey */
 200         Idlist keys;
 201         AuthenticationConnection *agent;
 202         /* hostbased */
 203         Sensitive *sensitive;
 204         /* kbd-interactive */
 205         int info_req_seen;
 206         /* generic */
 207         void *methoddata;
 208 };
 209 struct Authmethod {
 210         char    *name;          /* string to compare against server's list */
 211         int     (*userauth)(Authctxt *authctxt);
 212         void    (*cleanup)(Authctxt *authctxt);
 213         int     *enabled;       /* flag in option struct that enables method */
 214         int     *batch_flag;    /* flag in option struct that disables method */
 215 };
 216
 217 void    input_userauth_success(int, u_int32_t, void *);
 218 void    input_userauth_success_unexpected(int, u_int32_t, void *);
 219 void    input_userauth_failure(int, u_int32_t, void *);
 220 void    input_userauth_banner(int, u_int32_t, void *);
 221 void    input_userauth_error(int, u_int32_t, void *);
 222 void    input_userauth_info_req(int, u_int32_t, void *);
 223 void    input_userauth_pk_ok(int, u_int32_t, void *);
 224 void    input_userauth_passwd_changereq(int, u_int32_t, void *);
 225 void    input_userauth_jpake_server_step1(int, u_int32_t, void *);
 226 void    input_userauth_jpake_server_step2(int, u_int32_t, void *);
 227 void    input_userauth_jpake_server_confirm(int, u_int32_t, void *);
 228
 229 int     userauth_none(Authctxt *);
 230 int     userauth_pubkey(Authctxt *);
 231 int     userauth_passwd(Authctxt *);
 232 int     userauth_kbdint(Authctxt *);
 233 int     userauth_hostbased(Authctxt *);
 234 int     userauth_jpake(Authctxt *);
 235
 236 void    userauth_jpake_cleanup(Authctxt *);
 237
 238 #ifdef GSSAPI
 239 int     userauth_gssapi(Authctxt *authctxt);
 240 void    input_gssapi_response(int type, u_int32_t, void *);
 241 void    input_gssapi_token(int type, u_int32_t, void *);
 242 void    input_gssapi_hash(int type, u_int32_t, void *);
 243 void    input_gssapi_error(int, u_int32_t, void *);
 244 void    input_gssapi_errtok(int, u_int32_t, void *);
 245 #endif
 246
 247 void    userauth(Authctxt *, char *);
 248
 249 static int sign_and_send_pubkey(Authctxt *, Identity *);
 250 static void pubkey_prepare(Authctxt *);
 251 static void pubkey_cleanup(Authctxt *);
 252 static Key *load_identity_file(char *);
 253
 254 static Authmethod *authmethod_get(char *authlist);
 255 static Authmethod *authmethod_lookup(const char *name);
 256 static char *authmethods_get(void);
 257
 258 Authmethod authmethods[] = {
 259 #ifdef GSSAPI
 260         {"gssapi-with-mic",
 261                 userauth_gssapi,
 262                 NULL,
 263                 &options.gss_authentication,
 264                 NULL},
 265 #endif
 266         {"hostbased",
 267                 userauth_hostbased,
 268                 NULL,
 269                 &options.hostbased_authentication,
 270                 NULL},
 271         {"publickey",
 272                 userauth_pubkey,
 273                 NULL,
 274                 &options.pubkey_authentication,
 275                 NULL},
 276 #ifdef JPAKE
 277         {"jpake-01@openssh.com",
 278                 userauth_jpake,
 279                 userauth_jpake_cleanup,
 280                 &options.zero_knowledge_password_authentication,
 281                 &options.batch_mode},
 282 #endif
 283         {"keyboard-interactive",
 284                 userauth_kbdint,
 285                 NULL,
 286                 &options.kbd_interactive_authentication,
 287                 &options.batch_mode},
 288         {"password",
 289                 userauth_passwd,
 290                 NULL,
 291                 &options.password_authentication,
 292                 &options.batch_mode},
 293         {"none",
 294                 userauth_none,
 295                 NULL,
 296                 NULL,
 297                 NULL},
 298         {NULL, NULL, NULL, NULL, NULL}
 299 };
 300
 301 void
 302 ssh_userauth2(const char *local_user, const char *server_user, char *host,
 303     Sensitive *sensitive)
 304 {
 305         Authctxt authctxt;
 306         int type;
 307
 308         if (options.challenge_response_authentication)
 309                 options.kbd_interactive_authentication = 1;
 310
 311         packet_start(SSH2_MSG_SERVICE_REQUEST);
 312         packet_put_cstring("ssh-userauth");
 313         packet_send();
 314         debug("SSH2_MSG_SERVICE_REQUEST sent");
 315         packet_write_wait();
 316         type = packet_read();
 317         if (type != SSH2_MSG_SERVICE_ACCEPT)
 318                 fatal("Server denied authentication request: %d", type);
 319         if (packet_remaining() > 0) {
 320                 char *reply = packet_get_string(NULL);
 321                 debug2("service_accept: %s", reply);
 322                 xfree(reply);
 323         } else {
 324                 debug2("buggy server: service_accept w/o service");
 325         }
 326         packet_check_eom();
 327         debug("SSH2_MSG_SERVICE_ACCEPT received");
 328
 329         if (options.preferred_authentications == NULL)
 330                 options.preferred_authentications = authmethods_get();
 331
 332         /* setup authentication context */
 333         memset(&authctxt, 0, sizeof(authctxt));
 334         pubkey_prepare(&authctxt);
 335         authctxt.server_user = server_user;
 336         authctxt.local_user = local_user;
 337         authctxt.host = host;
 338         authctxt.service = "ssh-connection";            /* service name */
 339         authctxt.success = 0;
 340         authctxt.method = authmethod_lookup("none");
 341         authctxt.authlist = NULL;
 342         authctxt.methoddata = NULL;
 343         authctxt.sensitive = sensitive;
 344         authctxt.info_req_seen = 0;
 345         if (authctxt.method == NULL)
 346                 fatal("ssh_userauth2: internal error: cannot send userauth none request");
 347
 348         /* initial userauth request */
 349         userauth_none(&authctxt);
 350
 351         dispatch_init(&input_userauth_error);
 352         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
 353         dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
 354         dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 355         dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 356
 357         pubkey_cleanup(&authctxt);
 358         dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
 359
 360         debug("Authentication succeeded (%s).", authctxt.method->name);
 361 }
 362
 363 void
 364 userauth(Authctxt *authctxt, char *authlist)
 365 {
 366         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 367                 authctxt->method->cleanup(authctxt);
 368
 369         if (authctxt->methoddata) {
 370                 xfree(authctxt->methoddata);
 371                 authctxt->methoddata = NULL;
 372         }
 373         if (authlist == NULL) {
 374                 authlist = authctxt->authlist;
 375         } else {
 376                 if (authctxt->authlist)
 377                         xfree(authctxt->authlist);
 378                 authctxt->authlist = authlist;
 379         }
 380         for (;;) {
 381                 Authmethod *method = authmethod_get(authlist);
 382                 if (method == NULL)
 383                         fatal("Permission denied (%s).", authlist);
 384                 authctxt->method = method;
 385
 386                 /* reset the per method handler */
 387                 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
 388                     SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
 389
 390                 /* and try new method */
 391                 if (method->userauth(authctxt) != 0) {
 392                         debug2("we sent a %s packet, wait for reply", method->name);
 393                         break;
 394                 } else {
 395                         debug2("we did not send a packet, disable method");
 396                         method->enabled = NULL;
 397                 }
 398         }
 399 }
 400
 401 /* ARGSUSED */
 402 void
 403 input_userauth_error(int type, u_int32_t seq, void *ctxt)
 404 {
 405         fatal("input_userauth_error: bad message during authentication: "
 406             "type %d", type);
 407 }
 408
 409 /* ARGSUSED */
 410 void
 411 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
 412 {
 413         char *msg, *raw, *lang;
 414         u_int len;
 415
 416         debug3("input_userauth_banner");
 417         raw = packet_get_string(&len);
 418         lang = packet_get_string(NULL);
 419         if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
 420                 if (len > 65536)
 421                         len = 65536;
 422                 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
 423                 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL);
 424                 fprintf(stderr, "%s", msg);
 425                 xfree(msg);
 426         }
 427         xfree(raw);
 428         xfree(lang);
 429 }
 430
 431 /* ARGSUSED */
 432 void
 433 input_userauth_success(int type, u_int32_t seq, void *ctxt)
 434 {
 435         Authctxt *authctxt = ctxt;
 436
 437         if (authctxt == NULL)
 438                 fatal("input_userauth_success: no authentication context");
 439         if (authctxt->authlist) {
 440                 xfree(authctxt->authlist);
 441                 authctxt->authlist = NULL;
 442         }
 443         if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
 444                 authctxt->method->cleanup(authctxt);
 445         if (authctxt->methoddata) {
 446                 xfree(authctxt->methoddata);
 447                 authctxt->methoddata = NULL;
 448         }
 449         authctxt->success = 1;                  /* break out */
 450 }
 451
 452 void
 453 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
 454 {
 455         Authctxt *authctxt = ctxt;
 456
 457         if (authctxt == NULL)
 458                 fatal("%s: no authentication context", __func__);
 459
 460         fatal("Unexpected authentication success during %s.",
 461             authctxt->method->name);
 462 }
 463
 464 /* ARGSUSED */
 465 void
 466 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
 467 {
 468         Authctxt *authctxt = ctxt;
 469         char *authlist = NULL;
 470         int partial;
 471
 472         if (authctxt == NULL)
 473                 fatal("input_userauth_failure: no authentication context");
 474
 475         authlist = packet_get_string(NULL);
 476         partial = packet_get_char();
 477         packet_check_eom();
 478
 479         if (partial != 0)
 480                 logit("Authenticated with partial success.");
 481         debug("Authentications that can continue: %s", authlist);
 482
 483         userauth(authctxt, authlist);
 484 }
 485
 486 /* ARGSUSED */
 487 void
 488 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
 489 {
 490         Authctxt *authctxt = ctxt;
 491         Key *key = NULL;
 492         Identity *id = NULL;
 493         Buffer b;
 494         int pktype, sent = 0;
 495         u_int alen, blen;
 496         char *pkalg, *fp;
 497         u_char *pkblob;
 498
 499         if (authctxt == NULL)
 500                 fatal("input_userauth_pk_ok: no authentication context");
 501         if (datafellows & SSH_BUG_PKOK) {
 502                 /* this is similar to SSH_BUG_PKAUTH */
 503                 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
 504                 pkblob = packet_get_string(&blen);
 505                 buffer_init(&b);
 506                 buffer_append(&b, pkblob, blen);
 507                 pkalg = buffer_get_string(&b, &alen);
 508                 buffer_free(&b);
 509         } else {
 510                 pkalg = packet_get_string(&alen);
 511                 pkblob = packet_get_string(&blen);
 512         }
 513         packet_check_eom();
 514
 515         debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 516
 517         if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
 518                 debug("unknown pkalg %s", pkalg);
 519                 goto done;
 520         }
 521         if ((key = key_from_blob(pkblob, blen)) == NULL) {
 522                 debug("no key from blob. pkalg %s", pkalg);
 523                 goto done;
 524         }
 525         if (key->type != pktype) {
 526                 error("input_userauth_pk_ok: type mismatch "
 527                     "for decoded key (received %d, expected %d)",
 528                     key->type, pktype);
 529                 goto done;
 530         }
 531         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
 532         debug2("input_userauth_pk_ok: fp %s", fp);
 533         xfree(fp);
 534
 535         /*
 536          * search keys in the reverse order, because last candidate has been
 537          * moved to the end of the queue.  this also avoids confusion by
 538          * duplicate keys
 539          */
 540         TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
 541                 if (key_equal(key, id->key)) {
 542                         sent = sign_and_send_pubkey(authctxt, id);
 543                         break;
 544                 }
 545         }
 546 done:
 547         if (key != NULL)
 548                 key_free(key);
 549         xfree(pkalg);
 550         xfree(pkblob);
 551
 552         /* try another method if we did not send a packet */
 553         if (sent == 0)
 554                 userauth(authctxt, NULL);
 555 }
 556
 557 #ifdef GSSAPI
 558 int
 559 userauth_gssapi(Authctxt *authctxt)
 560 {
 561         Gssctxt *gssctxt = NULL;
 562         static gss_OID_set gss_supported = NULL;
 563         static u_int mech = 0;
 564         OM_uint32 min;
 565         int ok = 0;
 566
 567         /* Try one GSSAPI method at a time, rather than sending them all at
 568          * once. */
 569
 570         if (gss_supported == NULL)
 571                 gss_indicate_mechs(&min, &gss_supported);
 572
 573         /* Check to see if the mechanism is usable before we offer it */
 574         while (mech < gss_supported->count && !ok) {
 575                 /* My DER encoding requires length<128 */
 576                 if (gss_supported->elements[mech].length < 128 &&
 577                     ssh_gssapi_check_mechanism(&gssctxt,
 578                     &gss_supported->elements[mech], authctxt->host)) {
 579                         ok = 1; /* Mechanism works */
 580                 } else {
 581                         mech++;
 582                 }
 583         }
 584
 585         if (!ok)
 586                 return 0;
 587
 588         authctxt->methoddata=(void *)gssctxt;
 589
 590         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 591         packet_put_cstring(authctxt->server_user);
 592         packet_put_cstring(authctxt->service);
 593         packet_put_cstring(authctxt->method->name);
 594
 595         packet_put_int(1);
 596
 597         packet_put_int((gss_supported->elements[mech].length) + 2);
 598         packet_put_char(SSH_GSS_OIDTYPE);
 599         packet_put_char(gss_supported->elements[mech].length);
 600         packet_put_raw(gss_supported->elements[mech].elements,
 601             gss_supported->elements[mech].length);
 602
 603         packet_send();
 604
 605         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
 606         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 607         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
 608         dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 609
 610         mech++; /* Move along to next candidate */
 611
 612         return 1;
 613 }
 614
 615 static OM_uint32
 616 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
 617 {
 618         Authctxt *authctxt = ctxt;
 619         Gssctxt *gssctxt = authctxt->methoddata;
 620         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 621         gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
 622         gss_buffer_desc gssbuf;
 623         OM_uint32 status, ms, flags;
 624         Buffer b;
 625
 626         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 627             recv_tok, &send_tok, &flags);
 628
 629         if (send_tok.length > 0) {
 630                 if (GSS_ERROR(status))
 631                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 632                 else
 633                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 634
 635                 packet_put_string(send_tok.value, send_tok.length);
 636                 packet_send();
 637                 gss_release_buffer(&ms, &send_tok);
 638         }
 639
 640         if (status == GSS_S_COMPLETE) {
 641                 /* send either complete or MIC, depending on mechanism */
 642                 if (!(flags & GSS_C_INTEG_FLAG)) {
 643                         packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
 644                         packet_send();
 645                 } else {
 646                         ssh_gssapi_buildmic(&b, authctxt->server_user,
 647                             authctxt->service, "gssapi-with-mic");
 648
 649                         gssbuf.value = buffer_ptr(&b);
 650                         gssbuf.length = buffer_len(&b);
 651
 652                         status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
 653
 654                         if (!GSS_ERROR(status)) {
 655                                 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
 656                                 packet_put_string(mic.value, mic.length);
 657
 658                                 packet_send();
 659                         }
 660
 661                         buffer_free(&b);
 662                         gss_release_buffer(&ms, &mic);
 663                 }
 664         }
 665
 666         return status;
 667 }
 668
 669 /* ARGSUSED */
 670 void
 671 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
 672 {
 673         Authctxt *authctxt = ctxt;
 674         Gssctxt *gssctxt;
 675         int oidlen;
 676         char *oidv;
 677
 678         if (authctxt == NULL)
 679                 fatal("input_gssapi_response: no authentication context");
 680         gssctxt = authctxt->methoddata;
 681
 682         /* Setup our OID */
 683         oidv = packet_get_string(&oidlen);
 684
 685         if (oidlen <= 2 ||
 686             oidv[0] != SSH_GSS_OIDTYPE ||
 687             oidv[1] != oidlen - 2) {
 688                 xfree(oidv);
 689                 debug("Badly encoded mechanism OID received");
 690                 userauth(authctxt, NULL);
 691                 return;
 692         }
 693
 694         if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
 695                 fatal("Server returned different OID than expected");
 696
 697         packet_check_eom();
 698
 699         xfree(oidv);
 700
 701         if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
 702                 /* Start again with next method on list */
 703                 debug("Trying to start again");
 704                 userauth(authctxt, NULL);
 705                 return;
 706         }
 707 }
 708
 709 /* ARGSUSED */
 710 void
 711 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 712 {
 713         Authctxt *authctxt = ctxt;
 714         gss_buffer_desc recv_tok;
 715         OM_uint32 status;
 716         u_int slen;
 717
 718         if (authctxt == NULL)
 719                 fatal("input_gssapi_response: no authentication context");
 720
 721         recv_tok.value = packet_get_string(&slen);
 722         recv_tok.length = slen; /* safe typecast */
 723
 724         packet_check_eom();
 725
 726         status = process_gssapi_token(ctxt, &recv_tok);
 727
 728         xfree(recv_tok.value);
 729
 730         if (GSS_ERROR(status)) {
 731                 /* Start again with the next method in the list */
 732                 userauth(authctxt, NULL);
 733                 return;
 734         }
 735 }
 736
 737 /* ARGSUSED */
 738 void
 739 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 740 {
 741         Authctxt *authctxt = ctxt;
 742         Gssctxt *gssctxt;
 743         gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 744         gss_buffer_desc recv_tok;
 745         OM_uint32 status, ms;
 746         u_int len;
 747
 748         if (authctxt == NULL)
 749                 fatal("input_gssapi_response: no authentication context");
 750         gssctxt = authctxt->methoddata;
 751
 752         recv_tok.value = packet_get_string(&len);
 753         recv_tok.length = len;
 754
 755         packet_check_eom();
 756
 757         /* Stick it into GSSAPI and see what it says */
 758         status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
 759             &recv_tok, &send_tok, NULL);
 760
 761         xfree(recv_tok.value);
 762         gss_release_buffer(&ms, &send_tok);
 763
 764         /* Server will be returning a failed packet after this one */
 765 }
 766
 767 /* ARGSUSED */
 768 void
 769 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
 770 {
 771         OM_uint32 maj, min;
 772         char *msg;
 773         char *lang;
 774
 775         maj=packet_get_int();
 776         min=packet_get_int();
 777         msg=packet_get_string(NULL);
 778         lang=packet_get_string(NULL);
 779
 780         packet_check_eom();
 781
 782         debug("Server GSSAPI Error:\n%s", msg);
 783         xfree(msg);
 784         xfree(lang);
 785 }
 786 #endif /* GSSAPI */
 787
 788 int
 789 userauth_none(Authctxt *authctxt)
 790 {
 791         /* initial userauth request */
 792         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 793         packet_put_cstring(authctxt->server_user);
 794         packet_put_cstring(authctxt->service);
 795         packet_put_cstring(authctxt->method->name);
 796         packet_send();
 797         return 1;
 798 }
 799
 800 int
 801 userauth_passwd(Authctxt *authctxt)
 802 {
 803         static int attempt = 0;
 804         char prompt[150];
 805         char *password;
 806
 807         if (attempt++ >= options.number_of_password_prompts)
 808                 return 0;
 809
 810         if (attempt != 1)
 811                 error("Permission denied, please try again.");
 812
 813         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
 814             authctxt->server_user, authctxt->host);
 815         password = read_passphrase(prompt, 0);
 816         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 817         packet_put_cstring(authctxt->server_user);
 818         packet_put_cstring(authctxt->service);
 819         packet_put_cstring(authctxt->method->name);
 820         packet_put_char(0);
 821         packet_put_cstring(password);
 822         memset(password, 0, strlen(password));
 823         xfree(password);
 824         packet_add_padding(64);
 825         packet_send();
 826
 827         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 828             &input_userauth_passwd_changereq);
 829
 830         return 1;
 831 }
 832
 833 /*
 834  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 835  */
 836 /* ARGSUSED */
 837 void
 838 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 839 {
 840         Authctxt *authctxt = ctxt;
 841         char *info, *lang, *password = NULL, *retype = NULL;
 842         char prompt[150];
 843
 844         debug2("input_userauth_passwd_changereq");
 845
 846         if (authctxt == NULL)
 847                 fatal("input_userauth_passwd_changereq: "
 848                     "no authentication context");
 849
 850         info = packet_get_string(NULL);
 851         lang = packet_get_string(NULL);
 852         if (strlen(info) > 0)
 853                 logit("%s", info);
 854         xfree(info);
 855         xfree(lang);
 856         packet_start(SSH2_MSG_USERAUTH_REQUEST);
 857         packet_put_cstring(authctxt->server_user);
 858         packet_put_cstring(authctxt->service);
 859         packet_put_cstring(authctxt->method->name);
 860         packet_put_char(1);                     /* additional info */
 861         snprintf(prompt, sizeof(prompt),
 862             "Enter %.30s@%.128s's old password: ",
 863             authctxt->server_user, authctxt->host);
 864         password = read_passphrase(prompt, 0);
 865         packet_put_cstring(password);
 866         memset(password, 0, strlen(password));
 867         xfree(password);
 868         password = NULL;
 869         while (password == NULL) {
 870                 snprintf(prompt, sizeof(prompt),
 871                     "Enter %.30s@%.128s's new password: ",
 872                     authctxt->server_user, authctxt->host);
 873                 password = read_passphrase(prompt, RP_ALLOW_EOF);
 874                 if (password == NULL) {
 875                         /* bail out */
 876                         return;
 877                 }
 878                 snprintf(prompt, sizeof(prompt),
 879                     "Retype %.30s@%.128s's new password: ",
 880                     authctxt->server_user, authctxt->host);
 881                 retype = read_passphrase(prompt, 0);
 882                 if (strcmp(password, retype) != 0) {
 883                         memset(password, 0, strlen(password));
 884                         xfree(password);
 885                         logit("Mismatch; try again, EOF to quit.");
 886                         password = NULL;
 887                 }
 888                 memset(retype, 0, strlen(retype));
 889                 xfree(retype);
 890         }
 891         packet_put_cstring(password);
 892         memset(password, 0, strlen(password));
 893         xfree(password);
 894         packet_add_padding(64);
 895         packet_send();
 896
 897         dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
 898             &input_userauth_passwd_changereq);
 899 }
 900
 901 #ifdef JPAKE
 902 static char *
 903 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt)
 904 {
 905         /* OpenBSD crypt(3) handles all of these */
 906         if (strcmp(crypt_scheme, "crypt") == 0 ||
 907             strcmp(crypt_scheme, "bcrypt") == 0 ||
 908             strcmp(crypt_scheme, "md5crypt") == 0 ||
 909             strcmp(crypt_scheme, "crypt-extended") == 0)
 910                 return xstrdup(crypt(password, salt));
 911         error("%s: unsupported password encryption scheme \"%.100s\"",
 912             __func__, crypt_scheme);
 913         return NULL;
 914 }
 915
 916 static BIGNUM *
 917 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme,
 918     const char *salt)
 919 {
 920         char prompt[256], *password, *crypted;
 921         u_char *secret;
 922         u_int secret_len;
 923         BIGNUM *ret;
 924
 925         snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ",
 926             authctxt->server_user, authctxt->host);
 927         password = read_passphrase(prompt, 0);
 928
 929         if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) {
 930                 logit("Disabling %s authentication", authctxt->method->name);
 931                 authctxt->method->enabled = NULL;
 932                 /* Continue with an empty password to fail gracefully */
 933                 crypted = xstrdup("");
 934         }
 935
 936 #ifdef JPAKE_DEBUG
 937         debug3("%s: salt = %s", __func__, salt);
 938         debug3("%s: scheme = %s", __func__, crypt_scheme);
 939         debug3("%s: crypted = %s", __func__, crypted);
 940 #endif
 941
 942         if (hash_buffer(crypted, strlen(crypted), EVP_sha256(),
 943             &secret, &secret_len) != 0)
 944                 fatal("%s: hash_buffer", __func__);
 945
 946         bzero(password, strlen(password));
 947         bzero(crypted, strlen(crypted));
 948         xfree(password);
 949         xfree(crypted);
 950
 951         if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL)
 952                 fatal("%s: BN_bin2bn (secret)", __func__);
 953         bzero(secret, secret_len);
 954         xfree(secret);
 955
 956         return ret;
 957 }
 958
 959 /* ARGSUSED */
 960 void
 961 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt)
 962 {
 963         Authctxt *authctxt = ctxt;
 964         struct jpake_ctx *pctx = authctxt->methoddata;
 965         u_char *x3_proof, *x4_proof, *x2_s_proof;
 966         u_int x3_proof_len, x4_proof_len, x2_s_proof_len;
 967         char *crypt_scheme, *salt;
 968
 969         /* Disable this message */
 970         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL);
 971
 972         if ((pctx->g_x3 = BN_new()) == NULL ||
 973             (pctx->g_x4 = BN_new()) == NULL)
 974                 fatal("%s: BN_new", __func__);
 975
 976         /* Fetch step 1 values */
 977         crypt_scheme = packet_get_string(NULL);
 978         salt = packet_get_string(NULL);
 979         pctx->server_id = packet_get_string(&pctx->server_id_len);
 980         packet_get_bignum2(pctx->g_x3);
 981         packet_get_bignum2(pctx->g_x4);
 982         x3_proof = packet_get_string(&x3_proof_len);
 983         x4_proof = packet_get_string(&x4_proof_len);
 984         packet_check_eom();
 985
 986         JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__));
 987
 988         /* Obtain password and derive secret */
 989         pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt);
 990         bzero(crypt_scheme, strlen(crypt_scheme));
 991         bzero(salt, strlen(salt));
 992         xfree(crypt_scheme);
 993         xfree(salt);
 994         JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__));
 995
 996         /* Calculate step 2 values */
 997         jpake_step2(pctx->grp, pctx->s, pctx->g_x1,
 998             pctx->g_x3, pctx->g_x4, pctx->x2,
 999             pctx->server_id, pctx->server_id_len,
1000             pctx->client_id, pctx->client_id_len,
1001             x3_proof, x3_proof_len,
1002             x4_proof, x4_proof_len,
1003             &pctx->a,
1004             &x2_s_proof, &x2_s_proof_len);
1005
1006         bzero(x3_proof, x3_proof_len);
1007         bzero(x4_proof, x4_proof_len);
1008         xfree(x3_proof);
1009         xfree(x4_proof);
1010
1011         JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__));
1012
1013         /* Send values for step 2 */
1014         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2);
1015         packet_put_bignum2(pctx->a);
1016         packet_put_string(x2_s_proof, x2_s_proof_len);
1017         packet_send();
1018
1019         bzero(x2_s_proof, x2_s_proof_len);
1020         xfree(x2_s_proof);
1021
1022         /* Expect step 2 packet from peer */
1023         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2,
1024             input_userauth_jpake_server_step2);
1025 }
1026
1027 /* ARGSUSED */
1028 void
1029 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt)
1030 {
1031         Authctxt *authctxt = ctxt;
1032         struct jpake_ctx *pctx = authctxt->methoddata;
1033         u_char *x4_s_proof;
1034         u_int x4_s_proof_len;
1035
1036         /* Disable this message */
1037         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL);
1038
1039         if ((pctx->b = BN_new()) == NULL)
1040                 fatal("%s: BN_new", __func__);
1041
1042         /* Fetch step 2 values */
1043         packet_get_bignum2(pctx->b);
1044         x4_s_proof = packet_get_string(&x4_s_proof_len);
1045         packet_check_eom();
1046
1047         JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__));
1048
1049         /* Derive shared key and calculate confirmation hash */
1050         jpake_key_confirm(pctx->grp, pctx->s, pctx->b,
1051             pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4,
1052             pctx->client_id, pctx->client_id_len,
1053             pctx->server_id, pctx->server_id_len,
1054             session_id2, session_id2_len,
1055             x4_s_proof, x4_s_proof_len,
1056             &pctx->k,
1057             &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len);
1058
1059         bzero(x4_s_proof, x4_s_proof_len);
1060         xfree(x4_s_proof);
1061
1062         JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__));
1063
1064         /* Send key confirmation proof */
1065         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM);
1066         packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len);
1067         packet_send();
1068
1069         /* Expect confirmation from peer */
1070         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM,
1071             input_userauth_jpake_server_confirm);
1072 }
1073
1074 /* ARGSUSED */
1075 void
1076 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt)
1077 {
1078         Authctxt *authctxt = ctxt;
1079         struct jpake_ctx *pctx = authctxt->methoddata;
1080
1081         /* Disable this message */
1082         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL);
1083
1084         pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len);
1085         packet_check_eom();
1086
1087         JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__));
1088
1089         /* Verify expected confirmation hash */
1090         if (jpake_check_confirm(pctx->k,
1091             pctx->server_id, pctx->server_id_len,
1092             session_id2, session_id2_len,
1093             pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1)
1094                 debug("%s: %s success", __func__, authctxt->method->name);
1095         else {
1096                 debug("%s: confirmation mismatch", __func__);
1097                 /* XXX stash this so if auth succeeds then we can warn/kill */
1098         }
1099
1100         userauth_jpake_cleanup(authctxt);
1101 }
1102 #endif /* JPAKE */
1103
1104 static int
1105 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
1106     u_char *data, u_int datalen)
1107 {
1108         Key *prv;
1109         int ret;
1110
1111         /* the agent supports this key */
1112         if (id->ac)
1113                 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1114                     data, datalen));
1115         /*
1116          * we have already loaded the private key or
1117          * the private key is stored in external hardware
1118          */
1119         if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1120                 return (key_sign(id->key, sigp, lenp, data, datalen));
1121         /* load the private key from the file */
1122         if ((prv = load_identity_file(id->filename)) == NULL)
1123                 return (-1);
1124         ret = key_sign(prv, sigp, lenp, data, datalen);
1125         key_free(prv);
1126         return (ret);
1127 }
1128
1129 static int
1130 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1131 {
1132         Buffer b;
1133         u_char *blob, *signature;
1134         u_int bloblen, slen;
1135         u_int skip = 0;
1136         int ret = -1;
1137         int have_sig = 1;
1138
1139         debug3("sign_and_send_pubkey");
1140
1141         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1142                 /* we cannot handle this key */
1143                 debug3("sign_and_send_pubkey: cannot handle key");
1144                 return 0;
1145         }
1146         /* data to be signed */
1147         buffer_init(&b);
1148         if (datafellows & SSH_OLD_SESSIONID) {
1149                 buffer_append(&b, session_id2, session_id2_len);
1150                 skip = session_id2_len;
1151         } else {
1152                 buffer_put_string(&b, session_id2, session_id2_len);
1153                 skip = buffer_len(&b);
1154         }
1155         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1156         buffer_put_cstring(&b, authctxt->server_user);
1157         buffer_put_cstring(&b,
1158             datafellows & SSH_BUG_PKSERVICE ?
1159             "ssh-userauth" :
1160             authctxt->service);
1161         if (datafellows & SSH_BUG_PKAUTH) {
1162                 buffer_put_char(&b, have_sig);
1163         } else {
1164                 buffer_put_cstring(&b, authctxt->method->name);
1165                 buffer_put_char(&b, have_sig);
1166                 buffer_put_cstring(&b, key_ssh_name(id->key));
1167         }
1168         buffer_put_string(&b, blob, bloblen);
1169
1170         /* generate signature */
1171         ret = identity_sign(id, &signature, &slen,
1172             buffer_ptr(&b), buffer_len(&b));
1173         if (ret == -1) {
1174                 xfree(blob);
1175                 buffer_free(&b);
1176                 return 0;
1177         }
1178 #ifdef DEBUG_PK
1179         buffer_dump(&b);
1180 #endif
1181         if (datafellows & SSH_BUG_PKSERVICE) {
1182                 buffer_clear(&b);
1183                 buffer_append(&b, session_id2, session_id2_len);
1184                 skip = session_id2_len;
1185                 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1186                 buffer_put_cstring(&b, authctxt->server_user);
1187                 buffer_put_cstring(&b, authctxt->service);
1188                 buffer_put_cstring(&b, authctxt->method->name);
1189                 buffer_put_char(&b, have_sig);
1190                 if (!(datafellows & SSH_BUG_PKAUTH))
1191                         buffer_put_cstring(&b, key_ssh_name(id->key));
1192                 buffer_put_string(&b, blob, bloblen);
1193         }
1194         xfree(blob);
1195
1196         /* append signature */
1197         buffer_put_string(&b, signature, slen);
1198         xfree(signature);
1199
1200         /* skip session id and packet type */
1201         if (buffer_len(&b) < skip + 1)
1202                 fatal("userauth_pubkey: internal error");
1203         buffer_consume(&b, skip + 1);
1204
1205         /* put remaining data from buffer into packet */
1206         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1207         packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1208         buffer_free(&b);
1209         packet_send();
1210
1211         return 1;
1212 }
1213
1214 static int
1215 send_pubkey_test(Authctxt *authctxt, Identity *id)
1216 {
1217         u_char *blob;
1218         u_int bloblen, have_sig = 0;
1219
1220         debug3("send_pubkey_test");
1221
1222         if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1223                 /* we cannot handle this key */
1224                 debug3("send_pubkey_test: cannot handle key");
1225                 return 0;
1226         }
1227         /* register callback for USERAUTH_PK_OK message */
1228         dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1229
1230         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1231         packet_put_cstring(authctxt->server_user);
1232         packet_put_cstring(authctxt->service);
1233         packet_put_cstring(authctxt->method->name);
1234         packet_put_char(have_sig);
1235         if (!(datafellows & SSH_BUG_PKAUTH))
1236                 packet_put_cstring(key_ssh_name(id->key));
1237         packet_put_string(blob, bloblen);
1238         xfree(blob);
1239         packet_send();
1240         return 1;
1241 }
1242
1243 static Key *
1244 load_identity_file(char *filename)
1245 {
1246         Key *private;
1247         char prompt[300], *passphrase;
1248         int perm_ok, quit, i;
1249         struct stat st;
1250
1251         if (stat(filename, &st) < 0) {
1252                 debug3("no such identity: %s", filename);
1253                 return NULL;
1254         }
1255         private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1256         if (!perm_ok)
1257                 return NULL;
1258         if (private == NULL) {
1259                 if (options.batch_mode)
1260                         return NULL;
1261                 snprintf(prompt, sizeof prompt,
1262                     "Enter passphrase for key '%.100s': ", filename);
1263                 for (i = 0; i < options.number_of_password_prompts; i++) {
1264                         passphrase = read_passphrase(prompt, 0);
1265                         if (strcmp(passphrase, "") != 0) {
1266                                 private = key_load_private_type(KEY_UNSPEC,
1267                                     filename, passphrase, NULL, NULL);
1268                                 quit = 0;
1269                         } else {
1270                                 debug2("no passphrase given, try next key");
1271                                 quit = 1;
1272                         }
1273                         memset(passphrase, 0, strlen(passphrase));
1274                         xfree(passphrase);
1275                         if (private != NULL || quit)
1276                                 break;
1277                         debug2("bad passphrase given, try again...");
1278                 }
1279         }
1280         return private;
1281 }
1282
1283 /*
1284  * try keys in the following order:
1285  *      1. agent keys that are found in the config file
1286  *      2. other agent keys
1287  *      3. keys that are only listed in the config file
1288  */
1289 static void
1290 pubkey_prepare(Authctxt *authctxt)
1291 {
1292         Identity *id;
1293         Idlist agent, files, *preferred;
1294         Key *key;
1295         AuthenticationConnection *ac;
1296         char *comment;
1297         int i, found;
1298
1299         TAILQ_INIT(&agent);     /* keys from the agent */
1300         TAILQ_INIT(&files);     /* keys from the config file */
1301         preferred = &authctxt->keys;
1302         TAILQ_INIT(preferred);  /* preferred order of keys */
1303
1304         /* list of keys stored in the filesystem */
1305         for (i = 0; i < options.num_identity_files; i++) {
1306                 key = options.identity_keys[i];
1307                 if (key && key->type == KEY_RSA1)
1308                         continue;
1309                 options.identity_keys[i] = NULL;
1310                 id = xcalloc(1, sizeof(*id));
1311                 id->key = key;
1312                 id->filename = xstrdup(options.identity_files[i]);
1313                 TAILQ_INSERT_TAIL(&files, id, next);
1314         }
1315         /* list of keys supported by the agent */
1316         if ((ac = ssh_get_authentication_connection())) {
1317                 for (key = ssh_get_first_identity(ac, &comment, 2);
1318                     key != NULL;
1319                     key = ssh_get_next_identity(ac, &comment, 2)) {
1320                         found = 0;
1321                         TAILQ_FOREACH(id, &files, next) {
1322                                 /* agent keys from the config file are preferred */
1323                                 if (key_equal(key, id->key)) {
1324                                         key_free(key);
1325                                         xfree(comment);
1326                                         TAILQ_REMOVE(&files, id, next);
1327                                         TAILQ_INSERT_TAIL(preferred, id, next);
1328                                         id->ac = ac;
1329                                         found = 1;
1330                                         break;
1331                                 }
1332                         }
1333                         if (!found && !options.identities_only) {
1334                                 id = xcalloc(1, sizeof(*id));
1335                                 id->key = key;
1336                                 id->filename = comment;
1337                                 id->ac = ac;
1338                                 TAILQ_INSERT_TAIL(&agent, id, next);
1339                         }
1340                 }
1341                 /* append remaining agent keys */
1342                 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1343                         TAILQ_REMOVE(&agent, id, next);
1344                         TAILQ_INSERT_TAIL(preferred, id, next);
1345                 }
1346                 authctxt->agent = ac;
1347         }
1348         /* append remaining keys from the config file */
1349         for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1350                 TAILQ_REMOVE(&files, id, next);
1351                 TAILQ_INSERT_TAIL(preferred, id, next);
1352         }
1353         TAILQ_FOREACH(id, preferred, next) {
1354                 debug2("key: %s (%p)", id->filename, id->key);
1355         }
1356 }
1357
1358 static void
1359 pubkey_cleanup(Authctxt *authctxt)
1360 {
1361         Identity *id;
1362
1363         if (authctxt->agent != NULL)
1364                 ssh_close_authentication_connection(authctxt->agent);
1365         for (id = TAILQ_FIRST(&authctxt->keys); id;
1366             id = TAILQ_FIRST(&authctxt->keys)) {
1367                 TAILQ_REMOVE(&authctxt->keys, id, next);
1368                 if (id->key)
1369                         key_free(id->key);
1370                 if (id->filename)
1371                         xfree(id->filename);
1372                 xfree(id);
1373         }
1374 }
1375
1376 int
1377 userauth_pubkey(Authctxt *authctxt)
1378 {
1379         Identity *id;
1380         int sent = 0;
1381
1382         while ((id = TAILQ_FIRST(&authctxt->keys))) {
1383                 if (id->tried++)
1384                         return (0);
1385                 /* move key to the end of the queue */
1386                 TAILQ_REMOVE(&authctxt->keys, id, next);
1387                 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1388                 /*
1389                  * send a test message if we have the public key. for
1390                  * encrypted keys we cannot do this and have to load the
1391                  * private key instead
1392                  */
1393                 if (id->key && id->key->type != KEY_RSA1) {
1394                         debug("Offering public key: %s", id->filename);
1395                         sent = send_pubkey_test(authctxt, id);
1396                 } else if (id->key == NULL) {
1397                         debug("Trying private key: %s", id->filename);
1398                         id->key = load_identity_file(id->filename);
1399                         if (id->key != NULL) {
1400                                 id->isprivate = 1;
1401                                 sent = sign_and_send_pubkey(authctxt, id);
1402                                 key_free(id->key);
1403                                 id->key = NULL;
1404                         }
1405                 }
1406                 if (sent)
1407                         return (sent);
1408         }
1409         return (0);
1410 }
1411
1412 /*
1413  * Send userauth request message specifying keyboard-interactive method.
1414  */
1415 int
1416 userauth_kbdint(Authctxt *authctxt)
1417 {
1418         static int attempt = 0;
1419
1420         if (attempt++ >= options.number_of_password_prompts)
1421                 return 0;
1422         /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1423         if (attempt > 1 && !authctxt->info_req_seen) {
1424                 debug3("userauth_kbdint: disable: no info_req_seen");
1425                 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1426                 return 0;
1427         }
1428
1429         debug2("userauth_kbdint");
1430         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1431         packet_put_cstring(authctxt->server_user);
1432         packet_put_cstring(authctxt->service);
1433         packet_put_cstring(authctxt->method->name);
1434         packet_put_cstring("");                                 /* lang */
1435         packet_put_cstring(options.kbd_interactive_devices ?
1436             options.kbd_interactive_devices : "");
1437         packet_send();
1438
1439         dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1440         return 1;
1441 }
1442
1443 /*
1444  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1445  */
1446 void
1447 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1448 {
1449         Authctxt *authctxt = ctxt;
1450         char *name, *inst, *lang, *prompt, *response;
1451         u_int num_prompts, i;
1452         int echo = 0;
1453
1454         debug2("input_userauth_info_req");
1455
1456         if (authctxt == NULL)
1457                 fatal("input_userauth_info_req: no authentication context");
1458
1459         authctxt->info_req_seen = 1;
1460
1461         name = packet_get_string(NULL);
1462         inst = packet_get_string(NULL);
1463         lang = packet_get_string(NULL);
1464         if (strlen(name) > 0)
1465                 logit("%s", name);
1466         if (strlen(inst) > 0)
1467                 logit("%s", inst);
1468         xfree(name);
1469         xfree(inst);
1470         xfree(lang);
1471
1472         num_prompts = packet_get_int();
1473         /*
1474          * Begin to build info response packet based on prompts requested.
1475          * We commit to providing the correct number of responses, so if
1476          * further on we run into a problem that prevents this, we have to
1477          * be sure and clean this up and send a correct error response.
1478          */
1479         packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1480         packet_put_int(num_prompts);
1481
1482         debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1483         for (i = 0; i < num_prompts; i++) {
1484                 prompt = packet_get_string(NULL);
1485                 echo = packet_get_char();
1486
1487                 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1488
1489                 packet_put_cstring(response);
1490                 memset(response, 0, strlen(response));
1491                 xfree(response);
1492                 xfree(prompt);
1493         }
1494         packet_check_eom(); /* done with parsing incoming message. */
1495
1496         packet_add_padding(64);
1497         packet_send();
1498 }
1499
1500 static int
1501 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1502     u_char *data, u_int datalen)
1503 {
1504         Buffer b;
1505         struct stat st;
1506         pid_t pid;
1507         int to[2], from[2], status, version = 2;
1508
1509         debug2("ssh_keysign called");
1510
1511         if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1512                 error("ssh_keysign: no installed: %s", strerror(errno));
1513                 return -1;
1514         }
1515         if (fflush(stdout) != 0)
1516                 error("ssh_keysign: fflush: %s", strerror(errno));
1517         if (pipe(to) < 0) {
1518                 error("ssh_keysign: pipe: %s", strerror(errno));
1519                 return -1;
1520         }
1521         if (pipe(from) < 0) {
1522                 error("ssh_keysign: pipe: %s", strerror(errno));
1523                 return -1;
1524         }
1525         if ((pid = fork()) < 0) {
1526                 error("ssh_keysign: fork: %s", strerror(errno));
1527                 return -1;
1528         }
1529         if (pid == 0) {
1530                 permanently_drop_suid(getuid());
1531                 close(from[0]);
1532                 if (dup2(from[1], STDOUT_FILENO) < 0)
1533                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1534                 close(to[1]);
1535                 if (dup2(to[0], STDIN_FILENO) < 0)
1536                         fatal("ssh_keysign: dup2: %s", strerror(errno));
1537                 close(from[1]);
1538                 close(to[0]);
1539                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1540                 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1541                     strerror(errno));
1542         }
1543         close(from[1]);
1544         close(to[0]);
1545
1546         buffer_init(&b);
1547         buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1548         buffer_put_string(&b, data, datalen);
1549         if (ssh_msg_send(to[1], version, &b) == -1)
1550                 fatal("ssh_keysign: couldn't send request");
1551
1552         if (ssh_msg_recv(from[0], &b) < 0) {
1553                 error("ssh_keysign: no reply");
1554                 buffer_free(&b);
1555                 return -1;
1556         }
1557         close(from[0]);
1558         close(to[1]);
1559
1560         while (waitpid(pid, &status, 0) < 0)
1561                 if (errno != EINTR)
1562                         break;
1563
1564         if (buffer_get_char(&b) != version) {
1565                 error("ssh_keysign: bad version");
1566                 buffer_free(&b);
1567                 return -1;
1568         }
1569         *sigp = buffer_get_string(&b, lenp);
1570         buffer_free(&b);
1571
1572         return 0;
1573 }
1574
1575 int
1576 userauth_hostbased(Authctxt *authctxt)
1577 {
1578         Key *private = NULL;
1579         Sensitive *sensitive = authctxt->sensitive;
1580         Buffer b;
1581         u_char *signature, *blob;
1582         char *chost, *pkalg, *p, myname[NI_MAXHOST];
1583         const char *service;
1584         u_int blen, slen;
1585         int ok, i, len, found = 0;
1586
1587         /* check for a useful key */
1588         for (i = 0; i < sensitive->nkeys; i++) {
1589                 private = sensitive->keys[i];
1590                 if (private && private->type != KEY_RSA1) {
1591                         found = 1;
1592                         /* we take and free the key */
1593                         sensitive->keys[i] = NULL;
1594                         break;
1595                 }
1596         }
1597         if (!found) {
1598                 debug("No more client hostkeys for hostbased authentication.");
1599                 return 0;
1600         }
1601         if (key_to_blob(private, &blob, &blen) == 0) {
1602                 key_free(private);
1603                 return 0;
1604         }
1605         /* figure out a name for the client host */
1606         p = NULL;
1607         if (packet_connection_is_on_socket())
1608                 p = get_local_name(packet_get_connection_in());
1609         if (p == NULL) {
1610                 if (gethostname(myname, sizeof(myname)) == -1) {
1611                         verbose("userauth_hostbased: gethostname: %s",
1612                             strerror(errno));
1613                 } else
1614                         p = xstrdup(myname);
1615         }
1616         if (p == NULL) {
1617                 error("userauth_hostbased: cannot get local ipaddr/name");
1618                 key_free(private);
1619                 xfree(blob);
1620                 return 0;
1621         }
1622         len = strlen(p) + 2;
1623         xasprintf(&chost, "%s.", p);
1624         debug2("userauth_hostbased: chost %s", chost);
1625         xfree(p);
1626
1627         service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1628             authctxt->service;
1629         pkalg = xstrdup(key_ssh_name(private));
1630         buffer_init(&b);
1631         /* construct data */
1632         buffer_put_string(&b, session_id2, session_id2_len);
1633         buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1634         buffer_put_cstring(&b, authctxt->server_user);
1635         buffer_put_cstring(&b, service);
1636         buffer_put_cstring(&b, authctxt->method->name);
1637         buffer_put_cstring(&b, pkalg);
1638         buffer_put_string(&b, blob, blen);
1639         buffer_put_cstring(&b, chost);
1640         buffer_put_cstring(&b, authctxt->local_user);
1641 #ifdef DEBUG_PK
1642         buffer_dump(&b);
1643 #endif
1644         if (sensitive->external_keysign)
1645                 ok = ssh_keysign(private, &signature, &slen,
1646                     buffer_ptr(&b), buffer_len(&b));
1647         else
1648                 ok = key_sign(private, &signature, &slen,
1649                     buffer_ptr(&b), buffer_len(&b));
1650         key_free(private);
1651         buffer_free(&b);
1652         if (ok != 0) {
1653                 error("key_sign failed");
1654                 xfree(chost);
1655                 xfree(pkalg);
1656                 xfree(blob);
1657                 return 0;
1658         }
1659         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1660         packet_put_cstring(authctxt->server_user);
1661         packet_put_cstring(authctxt->service);
1662         packet_put_cstring(authctxt->method->name);
1663         packet_put_cstring(pkalg);
1664         packet_put_string(blob, blen);
1665         packet_put_cstring(chost);
1666         packet_put_cstring(authctxt->local_user);
1667         packet_put_string(signature, slen);
1668         memset(signature, 's', slen);
1669         xfree(signature);
1670         xfree(chost);
1671         xfree(pkalg);
1672         xfree(blob);
1673
1674         packet_send();
1675         return 1;
1676 }
1677
1678 #ifdef JPAKE
1679 int
1680 userauth_jpake(Authctxt *authctxt)
1681 {
1682         struct jpake_ctx *pctx;
1683         u_char *x1_proof, *x2_proof;
1684         u_int x1_proof_len, x2_proof_len;
1685         static int attempt = 0; /* XXX share with userauth_password's? */
1686
1687         if (attempt++ >= options.number_of_password_prompts)
1688                 return 0;
1689         if (attempt != 1)
1690                 error("Permission denied, please try again.");
1691
1692         if (authctxt->methoddata != NULL)
1693                 fatal("%s: authctxt->methoddata already set (%p)",
1694                     __func__, authctxt->methoddata);
1695
1696         authctxt->methoddata = pctx = jpake_new();
1697
1698         /*
1699          * Send request immediately, to get the protocol going while
1700          * we do the initial computations.
1701          */
1702         packet_start(SSH2_MSG_USERAUTH_REQUEST);
1703         packet_put_cstring(authctxt->server_user);
1704         packet_put_cstring(authctxt->service);
1705         packet_put_cstring(authctxt->method->name);
1706         packet_send();
1707         packet_write_wait();
1708
1709         jpake_step1(pctx->grp,
1710             &pctx->client_id, &pctx->client_id_len,
1711             &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2,
1712             &x1_proof, &x1_proof_len,
1713             &x2_proof, &x2_proof_len);
1714
1715         JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__));
1716
1717         packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1);
1718         packet_put_string(pctx->client_id, pctx->client_id_len);
1719         packet_put_bignum2(pctx->g_x1);
1720         packet_put_bignum2(pctx->g_x2);
1721         packet_put_string(x1_proof, x1_proof_len);
1722         packet_put_string(x2_proof, x2_proof_len);
1723         packet_send();
1724
1725         bzero(x1_proof, x1_proof_len);
1726         bzero(x2_proof, x2_proof_len);
1727         xfree(x1_proof);
1728         xfree(x2_proof);
1729
1730         /* Expect step 1 packet from peer */
1731         dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1,
1732             input_userauth_jpake_server_step1);
1733         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS,
1734             &input_userauth_success_unexpected);
1735
1736         return 1;
1737 }
1738
1739 void
1740 userauth_jpake_cleanup(Authctxt *authctxt)
1741 {
1742         debug3("%s: clean up", __func__);
1743         if (authctxt->methoddata != NULL) {
1744                 jpake_free(authctxt->methoddata);
1745                 authctxt->methoddata = NULL;
1746         }
1747         dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
1748 }
1749 #endif /* JPAKE */
1750
1751 /* find auth method */
1752
1753 /*
1754  * given auth method name, if configurable options permit this method fill
1755  * in auth_ident field and return true, otherwise return false.
1756  */
1757 static int
1758 authmethod_is_enabled(Authmethod *method)
1759 {
1760         if (method == NULL)
1761                 return 0;
1762         /* return false if options indicate this method is disabled */
1763         if  (method->enabled == NULL || *method->enabled == 0)
1764                 return 0;
1765         /* return false if batch mode is enabled but method needs interactive mode */
1766         if  (method->batch_flag != NULL && *method->batch_flag != 0)
1767                 return 0;
1768         return 1;
1769 }
1770
1771 static Authmethod *
1772 authmethod_lookup(const char *name)
1773 {
1774         Authmethod *method = NULL;
1775         if (name != NULL)
1776                 for (method = authmethods; method->name != NULL; method++)
1777                         if (strcmp(name, method->name) == 0)
1778                                 return method;
1779         debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1780         return NULL;
1781 }
1782
1783 /* XXX internal state */
1784 static Authmethod *current = NULL;
1785 static char *supported = NULL;
1786 static char *preferred = NULL;
1787
1788 /*
1789  * Given the authentication method list sent by the server, return the
1790  * next method we should try.  If the server initially sends a nil list,
1791  * use a built-in default list.
1792  */
1793 static Authmethod *
1794 authmethod_get(char *authlist)
1795 {
1796         char *name = NULL;
1797         u_int next;
1798
1799         /* Use a suitable default if we're passed a nil list.  */
1800         if (authlist == NULL || strlen(authlist) == 0)
1801                 authlist = options.preferred_authentications;
1802
1803         if (supported == NULL || strcmp(authlist, supported) != 0) {
1804                 debug3("start over, passed a different list %s", authlist);
1805                 if (supported != NULL)
1806                         xfree(supported);
1807                 supported = xstrdup(authlist);
1808                 preferred = options.preferred_authentications;
1809                 debug3("preferred %s", preferred);
1810                 current = NULL;
1811         } else if (current != NULL && authmethod_is_enabled(current))
1812                 return current;
1813
1814         for (;;) {
1815                 if ((name = match_list(preferred, supported, &next)) == NULL) {
1816                         debug("No more authentication methods to try.");
1817                         current = NULL;
1818                         return NULL;
1819                 }
1820                 preferred += next;
1821                 debug3("authmethod_lookup %s", name);
1822                 debug3("remaining preferred: %s", preferred);
1823                 if ((current = authmethod_lookup(name)) != NULL &&
1824                     authmethod_is_enabled(current)) {
1825                         debug3("authmethod_is_enabled %s", name);
1826                         debug("Next authentication method: %s", name);
1827                         return current;
1828                 }
1829         }
1830 }
1831
1832 static char *
1833 authmethods_get(void)
1834 {
1835         Authmethod *method = NULL;
1836         Buffer b;
1837         char *list;
1838
1839         buffer_init(&b);
1840         for (method = authmethods; method->name != NULL; method++) {
1841                 if (authmethod_is_enabled(method)) {
1842                         if (buffer_len(&b) > 0)
1843                                 buffer_append(&b, ",", 1);
1844                         buffer_append(&b, method->name, strlen(method->name));
1845                 }
1846         }
1847         buffer_append(&b, "\0", 1);
1848         list = xstrdup(buffer_ptr(&b));
1849         buffer_free(&b);
1850         return list;
1851 }
1852