crypto/openssh/ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.177 2013/07/20 01:50:20 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * The authentication agent program.
   7  *
   8  * As far as I am concerned, the code I have written for this software
   9  * can be used freely for any purpose.  Any derived versions of this
  10  * software must be clearly marked as such, and if the derived work is
  11  * incompatible with the protocol description in the RFC file, it must be
  12  * called by a name other than "ssh" or "Secure Shell".
  13  *
  14  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  15  *
  16  * Redistribution and use in source and binary forms, with or without
  17  * modification, are permitted provided that the following conditions
  18  * are met:
  19  * 1. Redistributions of source code must retain the above copyright
  20  *    notice, this list of conditions and the following disclaimer.
  21  * 2. Redistributions in binary form must reproduce the above copyright
  22  *    notice, this list of conditions and the following disclaimer in the
  23  *    documentation and/or other materials provided with the distribution.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  26  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  27  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  28  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  29  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  30  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  31  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  32  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  33  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  34  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  35  */
  36
  37 #include "includes.h"
  38 __RCSID("$FreeBSD$");
  39
  40 #include <sys/types.h>
  41 #include <sys/param.h>
  42 #include <sys/resource.h>
  43 #include <sys/stat.h>
  44 #include <sys/socket.h>
  45 #ifdef HAVE_SYS_TIME_H
  46 # include <sys/time.h>
  47 #endif
  48 #ifdef HAVE_SYS_UN_H
  49 # include <sys/un.h>
  50 #endif
  51 #include "openbsd-compat/sys-queue.h"
  52
  53 #include <openssl/evp.h>
  54 #include <openssl/md5.h>
  55 #include "openbsd-compat/openssl-compat.h"
  56
  57 #include <errno.h>
  58 #include <fcntl.h>
  59 #ifdef HAVE_PATHS_H
  60 # include <paths.h>
  61 #endif
  62 #include <signal.h>
  63 #include <stdarg.h>
  64 #include <stdio.h>
  65 #include <stdlib.h>
  66 #include <time.h>
  67 #include <string.h>
  68 #include <unistd.h>
  69
  70 #include "xmalloc.h"
  71 #include "ssh.h"
  72 #include "rsa.h"
  73 #include "buffer.h"
  74 #include "key.h"
  75 #include "authfd.h"
  76 #include "compat.h"
  77 #include "log.h"
  78 #include "misc.h"
  79
  80 #ifdef ENABLE_PKCS11
  81 #include "ssh-pkcs11.h"
  82 #endif
  83
  84 #if defined(HAVE_SYS_PRCTL_H)
  85 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  86 #endif
  87
  88 typedef enum {
  89         AUTH_UNUSED,
  90         AUTH_SOCKET,
  91         AUTH_CONNECTION
  92 } sock_type;
  93
  94 typedef struct {
  95         int fd;
  96         sock_type type;
  97         Buffer input;
  98         Buffer output;
  99         Buffer request;
 100 } SocketEntry;
 101
 102 u_int sockets_alloc = 0;
 103 SocketEntry *sockets = NULL;
 104
 105 typedef struct identity {
 106         TAILQ_ENTRY(identity) next;
 107         Key *key;
 108         char *comment;
 109         char *provider;
 110         time_t death;
 111         u_int confirm;
 112 } Identity;
 113
 114 typedef struct {
 115         int nentries;
 116         TAILQ_HEAD(idqueue, identity) idlist;
 117 } Idtab;
 118
 119 /* private key table, one per protocol version */
 120 Idtab idtable[3];
 121
 122 int max_fd = 0;
 123
 124 /* pid of shell == parent of agent */
 125 pid_t parent_pid = -1;
 126 time_t parent_alive_interval = 0;
 127
 128 /* pathname and directory for AUTH_SOCKET */
 129 char socket_name[MAXPATHLEN];
 130 char socket_dir[MAXPATHLEN];
 131
 132 /* locking */
 133 int locked = 0;
 134 char *lock_passwd = NULL;
 135
 136 extern char *__progname;
 137
 138 /* Default lifetime in seconds (0 == forever) */
 139 static long lifetime = 0;
 140
 141 /*
 142  * Client connection count; incremented in new_socket() and decremented in
 143  * close_socket().  When it reaches 0, ssh-agent will exit.  Since it is
 144  * normally initialized to 1, it will never reach 0.  However, if the -x
 145  * option is specified, it is initialized to 0 in main(); in that case,
 146  * ssh-agent will exit as soon as it has had at least one client but no
 147  * longer has any.
 148  */
 149 static int xcount = 1;
 150
 151 static void
 152 close_socket(SocketEntry *e)
 153 {
 154         int last = 0;
 155
 156         if (e->type == AUTH_CONNECTION) {
 157                 debug("xcount %d -> %d", xcount, xcount - 1);
 158                 if (--xcount == 0)
 159                         last = 1;
 160         }
 161         close(e->fd);
 162         e->fd = -1;
 163         e->type = AUTH_UNUSED;
 164         buffer_free(&e->input);
 165         buffer_free(&e->output);
 166         buffer_free(&e->request);
 167         if (last)
 168                 cleanup_exit(0);
 169 }
 170
 171 static void
 172 idtab_init(void)
 173 {
 174         int i;
 175
 176         for (i = 0; i <=2; i++) {
 177                 TAILQ_INIT(&idtable[i].idlist);
 178                 idtable[i].nentries = 0;
 179         }
 180 }
 181
 182 /* return private key table for requested protocol version */
 183 static Idtab *
 184 idtab_lookup(int version)
 185 {
 186         if (version < 1 || version > 2)
 187                 fatal("internal error, bad protocol version %d", version);
 188         return &idtable[version];
 189 }
 190
 191 static void
 192 free_identity(Identity *id)
 193 {
 194         key_free(id->key);
 195         free(id->provider);
 196         free(id->comment);
 197         free(id);
 198 }
 199
 200 /* return matching private key for given public key */
 201 static Identity *
 202 lookup_identity(Key *key, int version)
 203 {
 204         Identity *id;
 205
 206         Idtab *tab = idtab_lookup(version);
 207         TAILQ_FOREACH(id, &tab->idlist, next) {
 208                 if (key_equal(key, id->key))
 209                         return (id);
 210         }
 211         return (NULL);
 212 }
 213
 214 /* Check confirmation of keysign request */
 215 static int
 216 confirm_key(Identity *id)
 217 {
 218         char *p;
 219         int ret = -1;
 220
 221         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 222         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 223             id->comment, p))
 224                 ret = 0;
 225         free(p);
 226
 227         return (ret);
 228 }
 229
 230 /* send list of supported public keys to 'client' */
 231 static void
 232 process_request_identities(SocketEntry *e, int version)
 233 {
 234         Idtab *tab = idtab_lookup(version);
 235         Identity *id;
 236         Buffer msg;
 237
 238         buffer_init(&msg);
 239         buffer_put_char(&msg, (version == 1) ?
 240             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 241         buffer_put_int(&msg, tab->nentries);
 242         TAILQ_FOREACH(id, &tab->idlist, next) {
 243                 if (id->key->type == KEY_RSA1) {
 244                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 245                         buffer_put_bignum(&msg, id->key->rsa->e);
 246                         buffer_put_bignum(&msg, id->key->rsa->n);
 247                 } else {
 248                         u_char *blob;
 249                         u_int blen;
 250                         key_to_blob(id->key, &blob, &blen);
 251                         buffer_put_string(&msg, blob, blen);
 252                         free(blob);
 253                 }
 254                 buffer_put_cstring(&msg, id->comment);
 255         }
 256         buffer_put_int(&e->output, buffer_len(&msg));
 257         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 258         buffer_free(&msg);
 259 }
 260
 261 /* ssh1 only */
 262 static void
 263 process_authentication_challenge1(SocketEntry *e)
 264 {
 265         u_char buf[32], mdbuf[16], session_id[16];
 266         u_int response_type;
 267         BIGNUM *challenge;
 268         Identity *id;
 269         int i, len;
 270         Buffer msg;
 271         MD5_CTX md;
 272         Key *key;
 273
 274         buffer_init(&msg);
 275         key = key_new(KEY_RSA1);
 276         if ((challenge = BN_new()) == NULL)
 277                 fatal("process_authentication_challenge1: BN_new failed");
 278
 279         (void) buffer_get_int(&e->request);                     /* ignored */
 280         buffer_get_bignum(&e->request, key->rsa->e);
 281         buffer_get_bignum(&e->request, key->rsa->n);
 282         buffer_get_bignum(&e->request, challenge);
 283
 284         /* Only protocol 1.1 is supported */
 285         if (buffer_len(&e->request) == 0)
 286                 goto failure;
 287         buffer_get(&e->request, session_id, 16);
 288         response_type = buffer_get_int(&e->request);
 289         if (response_type != 1)
 290                 goto failure;
 291
 292         id = lookup_identity(key, 1);
 293         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 294                 Key *private = id->key;
 295                 /* Decrypt the challenge using the private key. */
 296                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 297                         goto failure;
 298
 299                 /* The response is MD5 of decrypted challenge plus session id. */
 300                 len = BN_num_bytes(challenge);
 301                 if (len <= 0 || len > 32) {
 302                         logit("process_authentication_challenge: bad challenge length %d", len);
 303                         goto failure;
 304                 }
 305                 memset(buf, 0, 32);
 306                 BN_bn2bin(challenge, buf + 32 - len);
 307                 MD5_Init(&md);
 308                 MD5_Update(&md, buf, 32);
 309                 MD5_Update(&md, session_id, 16);
 310                 MD5_Final(mdbuf, &md);
 311
 312                 /* Send the response. */
 313                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 314                 for (i = 0; i < 16; i++)
 315                         buffer_put_char(&msg, mdbuf[i]);
 316                 goto send;
 317         }
 318
 319 failure:
 320         /* Unknown identity or protocol error.  Send failure. */
 321         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 322 send:
 323         buffer_put_int(&e->output, buffer_len(&msg));
 324         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 325         key_free(key);
 326         BN_clear_free(challenge);
 327         buffer_free(&msg);
 328 }
 329
 330 /* ssh2 only */
 331 static void
 332 process_sign_request2(SocketEntry *e)
 333 {
 334         u_char *blob, *data, *signature = NULL;
 335         u_int blen, dlen, slen = 0;
 336         extern int datafellows;
 337         int odatafellows;
 338         int ok = -1, flags;
 339         Buffer msg;
 340         Key *key;
 341
 342         datafellows = 0;
 343
 344         blob = buffer_get_string(&e->request, &blen);
 345         data = buffer_get_string(&e->request, &dlen);
 346
 347         flags = buffer_get_int(&e->request);
 348         odatafellows = datafellows;
 349         if (flags & SSH_AGENT_OLD_SIGNATURE)
 350                 datafellows = SSH_BUG_SIGBLOB;
 351
 352         key = key_from_blob(blob, blen);
 353         if (key != NULL) {
 354                 Identity *id = lookup_identity(key, 2);
 355                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 356                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 357                 key_free(key);
 358         }
 359         buffer_init(&msg);
 360         if (ok == 0) {
 361                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 362                 buffer_put_string(&msg, signature, slen);
 363         } else {
 364                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 365         }
 366         buffer_put_int(&e->output, buffer_len(&msg));
 367         buffer_append(&e->output, buffer_ptr(&msg),
 368             buffer_len(&msg));
 369         buffer_free(&msg);
 370         free(data);
 371         free(blob);
 372         free(signature);
 373         datafellows = odatafellows;
 374 }
 375
 376 /* shared */
 377 static void
 378 process_remove_identity(SocketEntry *e, int version)
 379 {
 380         u_int blen, bits;
 381         int success = 0;
 382         Key *key = NULL;
 383         u_char *blob;
 384
 385         switch (version) {
 386         case 1:
 387                 key = key_new(KEY_RSA1);
 388                 bits = buffer_get_int(&e->request);
 389                 buffer_get_bignum(&e->request, key->rsa->e);
 390                 buffer_get_bignum(&e->request, key->rsa->n);
 391
 392                 if (bits != key_size(key))
 393                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 394                             key_size(key), bits);
 395                 break;
 396         case 2:
 397                 blob = buffer_get_string(&e->request, &blen);
 398                 key = key_from_blob(blob, blen);
 399                 free(blob);
 400                 break;
 401         }
 402         if (key != NULL) {
 403                 Identity *id = lookup_identity(key, version);
 404                 if (id != NULL) {
 405                         /*
 406                          * We have this key.  Free the old key.  Since we
 407                          * don't want to leave empty slots in the middle of
 408                          * the array, we actually free the key there and move
 409                          * all the entries between the empty slot and the end
 410                          * of the array.
 411                          */
 412                         Idtab *tab = idtab_lookup(version);
 413                         if (tab->nentries < 1)
 414                                 fatal("process_remove_identity: "
 415                                     "internal error: tab->nentries %d",
 416                                     tab->nentries);
 417                         TAILQ_REMOVE(&tab->idlist, id, next);
 418                         free_identity(id);
 419                         tab->nentries--;
 420                         success = 1;
 421                 }
 422                 key_free(key);
 423         }
 424         buffer_put_int(&e->output, 1);
 425         buffer_put_char(&e->output,
 426             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 427 }
 428
 429 static void
 430 process_remove_all_identities(SocketEntry *e, int version)
 431 {
 432         Idtab *tab = idtab_lookup(version);
 433         Identity *id;
 434
 435         /* Loop over all identities and clear the keys. */
 436         for (id = TAILQ_FIRST(&tab->idlist); id;
 437             id = TAILQ_FIRST(&tab->idlist)) {
 438                 TAILQ_REMOVE(&tab->idlist, id, next);
 439                 free_identity(id);
 440         }
 441
 442         /* Mark that there are no identities. */
 443         tab->nentries = 0;
 444
 445         /* Send success. */
 446         buffer_put_int(&e->output, 1);
 447         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 448 }
 449
 450 /* removes expired keys and returns number of seconds until the next expiry */
 451 static time_t
 452 reaper(void)
 453 {
 454         time_t deadline = 0, now = monotime();
 455         Identity *id, *nxt;
 456         int version;
 457         Idtab *tab;
 458
 459         for (version = 1; version < 3; version++) {
 460                 tab = idtab_lookup(version);
 461                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 462                         nxt = TAILQ_NEXT(id, next);
 463                         if (id->death == 0)
 464                                 continue;
 465                         if (now >= id->death) {
 466                                 debug("expiring key '%s'", id->comment);
 467                                 TAILQ_REMOVE(&tab->idlist, id, next);
 468                                 free_identity(id);
 469                                 tab->nentries--;
 470                         } else
 471                                 deadline = (deadline == 0) ? id->death :
 472                                     MIN(deadline, id->death);
 473                 }
 474         }
 475         if (deadline == 0 || deadline <= now)
 476                 return 0;
 477         else
 478                 return (deadline - now);
 479 }
 480
 481 static void
 482 process_add_identity(SocketEntry *e, int version)
 483 {
 484         Idtab *tab = idtab_lookup(version);
 485         Identity *id;
 486         int type, success = 0, confirm = 0;
 487         char *type_name, *comment;
 488         time_t death = 0;
 489         Key *k = NULL;
 490 #ifdef OPENSSL_HAS_ECC
 491         BIGNUM *exponent;
 492         EC_POINT *q;
 493         char *curve;
 494 #endif
 495         u_char *cert;
 496         u_int len;
 497
 498         switch (version) {
 499         case 1:
 500                 k = key_new_private(KEY_RSA1);
 501                 (void) buffer_get_int(&e->request);             /* ignored */
 502                 buffer_get_bignum(&e->request, k->rsa->n);
 503                 buffer_get_bignum(&e->request, k->rsa->e);
 504                 buffer_get_bignum(&e->request, k->rsa->d);
 505                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 506
 507                 /* SSH and SSL have p and q swapped */
 508                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 509                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 510
 511                 /* Generate additional parameters */
 512                 rsa_generate_additional_parameters(k->rsa);
 513                 break;
 514         case 2:
 515                 type_name = buffer_get_string(&e->request, NULL);
 516                 type = key_type_from_name(type_name);
 517                 switch (type) {
 518                 case KEY_DSA:
 519                         k = key_new_private(type);
 520                         buffer_get_bignum2(&e->request, k->dsa->p);
 521                         buffer_get_bignum2(&e->request, k->dsa->q);
 522                         buffer_get_bignum2(&e->request, k->dsa->g);
 523                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 524                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 525                         break;
 526                 case KEY_DSA_CERT_V00:
 527                 case KEY_DSA_CERT:
 528                         cert = buffer_get_string(&e->request, &len);
 529                         if ((k = key_from_blob(cert, len)) == NULL)
 530                                 fatal("Certificate parse failed");
 531                         free(cert);
 532                         key_add_private(k);
 533                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 534                         break;
 535 #ifdef OPENSSL_HAS_ECC
 536                 case KEY_ECDSA:
 537                         k = key_new_private(type);
 538                         k->ecdsa_nid = key_ecdsa_nid_from_name(type_name);
 539                         curve = buffer_get_string(&e->request, NULL);
 540                         if (k->ecdsa_nid != key_curve_name_to_nid(curve))
 541                                 fatal("%s: curve names mismatch", __func__);
 542                         free(curve);
 543                         k->ecdsa = EC_KEY_new_by_curve_name(k->ecdsa_nid);
 544                         if (k->ecdsa == NULL)
 545                                 fatal("%s: EC_KEY_new_by_curve_name failed",
 546                                     __func__);
 547                         q = EC_POINT_new(EC_KEY_get0_group(k->ecdsa));
 548                         if (q == NULL)
 549                                 fatal("%s: BN_new failed", __func__);
 550                         if ((exponent = BN_new()) == NULL)
 551                                 fatal("%s: BN_new failed", __func__);
 552                         buffer_get_ecpoint(&e->request,
 553                                 EC_KEY_get0_group(k->ecdsa), q);
 554                         buffer_get_bignum2(&e->request, exponent);
 555                         if (EC_KEY_set_public_key(k->ecdsa, q) != 1)
 556                                 fatal("%s: EC_KEY_set_public_key failed",
 557                                     __func__);
 558                         if (EC_KEY_set_private_key(k->ecdsa, exponent) != 1)
 559                                 fatal("%s: EC_KEY_set_private_key failed",
 560                                     __func__);
 561                         if (key_ec_validate_public(EC_KEY_get0_group(k->ecdsa),
 562                             EC_KEY_get0_public_key(k->ecdsa)) != 0)
 563                                 fatal("%s: bad ECDSA public key", __func__);
 564                         if (key_ec_validate_private(k->ecdsa) != 0)
 565                                 fatal("%s: bad ECDSA private key", __func__);
 566                         BN_clear_free(exponent);
 567                         EC_POINT_free(q);
 568                         break;
 569                 case KEY_ECDSA_CERT:
 570                         cert = buffer_get_string(&e->request, &len);
 571                         if ((k = key_from_blob(cert, len)) == NULL)
 572                                 fatal("Certificate parse failed");
 573                         free(cert);
 574                         key_add_private(k);
 575                         if ((exponent = BN_new()) == NULL)
 576                                 fatal("%s: BN_new failed", __func__);
 577                         buffer_get_bignum2(&e->request, exponent);
 578                         if (EC_KEY_set_private_key(k->ecdsa, exponent) != 1)
 579                                 fatal("%s: EC_KEY_set_private_key failed",
 580                                     __func__);
 581                         if (key_ec_validate_public(EC_KEY_get0_group(k->ecdsa),
 582                             EC_KEY_get0_public_key(k->ecdsa)) != 0 ||
 583                             key_ec_validate_private(k->ecdsa) != 0)
 584                                 fatal("%s: bad ECDSA key", __func__);
 585                         BN_clear_free(exponent);
 586                         break;
 587 #endif /* OPENSSL_HAS_ECC */
 588                 case KEY_RSA:
 589                         k = key_new_private(type);
 590                         buffer_get_bignum2(&e->request, k->rsa->n);
 591                         buffer_get_bignum2(&e->request, k->rsa->e);
 592                         buffer_get_bignum2(&e->request, k->rsa->d);
 593                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 594                         buffer_get_bignum2(&e->request, k->rsa->p);
 595                         buffer_get_bignum2(&e->request, k->rsa->q);
 596
 597                         /* Generate additional parameters */
 598                         rsa_generate_additional_parameters(k->rsa);
 599                         break;
 600                 case KEY_RSA_CERT_V00:
 601                 case KEY_RSA_CERT:
 602                         cert = buffer_get_string(&e->request, &len);
 603                         if ((k = key_from_blob(cert, len)) == NULL)
 604                                 fatal("Certificate parse failed");
 605                         free(cert);
 606                         key_add_private(k);
 607                         buffer_get_bignum2(&e->request, k->rsa->d);
 608                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 609                         buffer_get_bignum2(&e->request, k->rsa->p);
 610                         buffer_get_bignum2(&e->request, k->rsa->q);
 611                         break;
 612                 default:
 613                         free(type_name);
 614                         buffer_clear(&e->request);
 615                         goto send;
 616                 }
 617                 free(type_name);
 618                 break;
 619         }
 620         /* enable blinding */
 621         switch (k->type) {
 622         case KEY_RSA:
 623         case KEY_RSA_CERT_V00:
 624         case KEY_RSA_CERT:
 625         case KEY_RSA1:
 626                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 627                         error("process_add_identity: RSA_blinding_on failed");
 628                         key_free(k);
 629                         goto send;
 630                 }
 631                 break;
 632         }
 633         comment = buffer_get_string(&e->request, NULL);
 634         if (k == NULL) {
 635                 free(comment);
 636                 goto send;
 637         }
 638         while (buffer_len(&e->request)) {
 639                 switch ((type = buffer_get_char(&e->request))) {
 640                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 641                         death = monotime() + buffer_get_int(&e->request);
 642                         break;
 643                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 644                         confirm = 1;
 645                         break;
 646                 default:
 647                         error("process_add_identity: "
 648                             "Unknown constraint type %d", type);
 649                         free(comment);
 650                         key_free(k);
 651                         goto send;
 652                 }
 653         }
 654         success = 1;
 655         if (lifetime && !death)
 656                 death = monotime() + lifetime;
 657         if ((id = lookup_identity(k, version)) == NULL) {
 658                 id = xcalloc(1, sizeof(Identity));
 659                 id->key = k;
 660                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 661                 /* Increment the number of identities. */
 662                 tab->nentries++;
 663         } else {
 664                 key_free(k);
 665                 free(id->comment);
 666         }
 667         id->comment = comment;
 668         id->death = death;
 669         id->confirm = confirm;
 670 send:
 671         buffer_put_int(&e->output, 1);
 672         buffer_put_char(&e->output,
 673             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 674 }
 675
 676 /* XXX todo: encrypt sensitive data with passphrase */
 677 static void
 678 process_lock_agent(SocketEntry *e, int lock)
 679 {
 680         int success = 0;
 681         char *passwd;
 682
 683         passwd = buffer_get_string(&e->request, NULL);
 684         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 685                 locked = 0;
 686                 memset(lock_passwd, 0, strlen(lock_passwd));
 687                 free(lock_passwd);
 688                 lock_passwd = NULL;
 689                 success = 1;
 690         } else if (!locked && lock) {
 691                 locked = 1;
 692                 lock_passwd = xstrdup(passwd);
 693                 success = 1;
 694         }
 695         memset(passwd, 0, strlen(passwd));
 696         free(passwd);
 697
 698         buffer_put_int(&e->output, 1);
 699         buffer_put_char(&e->output,
 700             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 701 }
 702
 703 static void
 704 no_identities(SocketEntry *e, u_int type)
 705 {
 706         Buffer msg;
 707
 708         buffer_init(&msg);
 709         buffer_put_char(&msg,
 710             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 711             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 712         buffer_put_int(&msg, 0);
 713         buffer_put_int(&e->output, buffer_len(&msg));
 714         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 715         buffer_free(&msg);
 716 }
 717
 718 #ifdef ENABLE_PKCS11
 719 static void
 720 process_add_smartcard_key(SocketEntry *e)
 721 {
 722         char *provider = NULL, *pin;
 723         int i, type, version, count = 0, success = 0, confirm = 0;
 724         time_t death = 0;
 725         Key **keys = NULL, *k;
 726         Identity *id;
 727         Idtab *tab;
 728
 729         provider = buffer_get_string(&e->request, NULL);
 730         pin = buffer_get_string(&e->request, NULL);
 731
 732         while (buffer_len(&e->request)) {
 733                 switch ((type = buffer_get_char(&e->request))) {
 734                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 735                         death = monotime() + buffer_get_int(&e->request);
 736                         break;
 737                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 738                         confirm = 1;
 739                         break;
 740                 default:
 741                         error("process_add_smartcard_key: "
 742                             "Unknown constraint type %d", type);
 743                         goto send;
 744                 }
 745         }
 746         if (lifetime && !death)
 747                 death = monotime() + lifetime;
 748
 749         count = pkcs11_add_provider(provider, pin, &keys);
 750         for (i = 0; i < count; i++) {
 751                 k = keys[i];
 752                 version = k->type == KEY_RSA1 ? 1 : 2;
 753                 tab = idtab_lookup(version);
 754                 if (lookup_identity(k, version) == NULL) {
 755                         id = xcalloc(1, sizeof(Identity));
 756                         id->key = k;
 757                         id->provider = xstrdup(provider);
 758                         id->comment = xstrdup(provider); /* XXX */
 759                         id->death = death;
 760                         id->confirm = confirm;
 761                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 762                         tab->nentries++;
 763                         success = 1;
 764                 } else {
 765                         key_free(k);
 766                 }
 767                 keys[i] = NULL;
 768         }
 769 send:
 770         free(pin);
 771         free(provider);
 772         free(keys);
 773         buffer_put_int(&e->output, 1);
 774         buffer_put_char(&e->output,
 775             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 776 }
 777
 778 static void
 779 process_remove_smartcard_key(SocketEntry *e)
 780 {
 781         char *provider = NULL, *pin = NULL;
 782         int version, success = 0;
 783         Identity *id, *nxt;
 784         Idtab *tab;
 785
 786         provider = buffer_get_string(&e->request, NULL);
 787         pin = buffer_get_string(&e->request, NULL);
 788         free(pin);
 789
 790         for (version = 1; version < 3; version++) {
 791                 tab = idtab_lookup(version);
 792                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 793                         nxt = TAILQ_NEXT(id, next);
 794                         if (!strcmp(provider, id->provider)) {
 795                                 TAILQ_REMOVE(&tab->idlist, id, next);
 796                                 free_identity(id);
 797                                 tab->nentries--;
 798                         }
 799                 }
 800         }
 801         if (pkcs11_del_provider(provider) == 0)
 802                 success = 1;
 803         else
 804                 error("process_remove_smartcard_key:"
 805                     " pkcs11_del_provider failed");
 806         free(provider);
 807         buffer_put_int(&e->output, 1);
 808         buffer_put_char(&e->output,
 809             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 810 }
 811 #endif /* ENABLE_PKCS11 */
 812
 813 /* dispatch incoming messages */
 814
 815 static void
 816 process_message(SocketEntry *e)
 817 {
 818         u_int msg_len, type;
 819         u_char *cp;
 820
 821         if (buffer_len(&e->input) < 5)
 822                 return;         /* Incomplete message. */
 823         cp = buffer_ptr(&e->input);
 824         msg_len = get_u32(cp);
 825         if (msg_len > 256 * 1024) {
 826                 close_socket(e);
 827                 return;
 828         }
 829         if (buffer_len(&e->input) < msg_len + 4)
 830                 return;
 831
 832         /* move the current input to e->request */
 833         buffer_consume(&e->input, 4);
 834         buffer_clear(&e->request);
 835         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 836         buffer_consume(&e->input, msg_len);
 837         type = buffer_get_char(&e->request);
 838
 839         /* check wheter agent is locked */
 840         if (locked && type != SSH_AGENTC_UNLOCK) {
 841                 buffer_clear(&e->request);
 842                 switch (type) {
 843                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 844                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 845                         /* send empty lists */
 846                         no_identities(e, type);
 847                         break;
 848                 default:
 849                         /* send a fail message for all other request types */
 850                         buffer_put_int(&e->output, 1);
 851                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 852                 }
 853                 return;
 854         }
 855
 856         debug("type %d", type);
 857         switch (type) {
 858         case SSH_AGENTC_LOCK:
 859         case SSH_AGENTC_UNLOCK:
 860                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 861                 break;
 862         /* ssh1 */
 863         case SSH_AGENTC_RSA_CHALLENGE:
 864                 process_authentication_challenge1(e);
 865                 break;
 866         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 867                 process_request_identities(e, 1);
 868                 break;
 869         case SSH_AGENTC_ADD_RSA_IDENTITY:
 870         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 871                 process_add_identity(e, 1);
 872                 break;
 873         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 874                 process_remove_identity(e, 1);
 875                 break;
 876         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 877                 process_remove_all_identities(e, 1);
 878                 break;
 879         /* ssh2 */
 880         case SSH2_AGENTC_SIGN_REQUEST:
 881                 process_sign_request2(e);
 882                 break;
 883         case SSH2_AGENTC_REQUEST_IDENTITIES:
 884                 process_request_identities(e, 2);
 885                 break;
 886         case SSH2_AGENTC_ADD_IDENTITY:
 887         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 888                 process_add_identity(e, 2);
 889                 break;
 890         case SSH2_AGENTC_REMOVE_IDENTITY:
 891                 process_remove_identity(e, 2);
 892                 break;
 893         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 894                 process_remove_all_identities(e, 2);
 895                 break;
 896 #ifdef ENABLE_PKCS11
 897         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 898         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 899                 process_add_smartcard_key(e);
 900                 break;
 901         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 902                 process_remove_smartcard_key(e);
 903                 break;
 904 #endif /* ENABLE_PKCS11 */
 905         default:
 906                 /* Unknown message.  Respond with failure. */
 907                 error("Unknown message %d", type);
 908                 buffer_clear(&e->request);
 909                 buffer_put_int(&e->output, 1);
 910                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 911                 break;
 912         }
 913 }
 914
 915 static void
 916 new_socket(sock_type type, int fd)
 917 {
 918         u_int i, old_alloc, new_alloc;
 919
 920         if (type == AUTH_CONNECTION) {
 921                 debug("xcount %d -> %d", xcount, xcount + 1);
 922                 ++xcount;
 923         }
 924         set_nonblock(fd);
 925
 926         if (fd > max_fd)
 927                 max_fd = fd;
 928
 929         for (i = 0; i < sockets_alloc; i++)
 930                 if (sockets[i].type == AUTH_UNUSED) {
 931                         sockets[i].fd = fd;
 932                         buffer_init(&sockets[i].input);
 933                         buffer_init(&sockets[i].output);
 934                         buffer_init(&sockets[i].request);
 935                         sockets[i].type = type;
 936                         return;
 937                 }
 938         old_alloc = sockets_alloc;
 939         new_alloc = sockets_alloc + 10;
 940         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 941         for (i = old_alloc; i < new_alloc; i++)
 942                 sockets[i].type = AUTH_UNUSED;
 943         sockets_alloc = new_alloc;
 944         sockets[old_alloc].fd = fd;
 945         buffer_init(&sockets[old_alloc].input);
 946         buffer_init(&sockets[old_alloc].output);
 947         buffer_init(&sockets[old_alloc].request);
 948         sockets[old_alloc].type = type;
 949 }
 950
 951 static int
 952 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
 953     struct timeval **tvpp)
 954 {
 955         u_int i, sz;
 956         int n = 0;
 957         static struct timeval tv;
 958         time_t deadline;
 959
 960         for (i = 0; i < sockets_alloc; i++) {
 961                 switch (sockets[i].type) {
 962                 case AUTH_SOCKET:
 963                 case AUTH_CONNECTION:
 964                         n = MAX(n, sockets[i].fd);
 965                         break;
 966                 case AUTH_UNUSED:
 967                         break;
 968                 default:
 969                         fatal("Unknown socket type %d", sockets[i].type);
 970                         break;
 971                 }
 972         }
 973
 974         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 975         if (*fdrp == NULL || sz > *nallocp) {
 976                 free(*fdrp);
 977                 free(*fdwp);
 978                 *fdrp = xmalloc(sz);
 979                 *fdwp = xmalloc(sz);
 980                 *nallocp = sz;
 981         }
 982         if (n < *fdl)
 983                 debug("XXX shrink: %d < %d", n, *fdl);
 984         *fdl = n;
 985         memset(*fdrp, 0, sz);
 986         memset(*fdwp, 0, sz);
 987
 988         for (i = 0; i < sockets_alloc; i++) {
 989                 switch (sockets[i].type) {
 990                 case AUTH_SOCKET:
 991                 case AUTH_CONNECTION:
 992                         FD_SET(sockets[i].fd, *fdrp);
 993                         if (buffer_len(&sockets[i].output) > 0)
 994                                 FD_SET(sockets[i].fd, *fdwp);
 995                         break;
 996                 default:
 997                         break;
 998                 }
 999         }
1000         deadline = reaper();
1001         if (parent_alive_interval != 0)
1002                 deadline = (deadline == 0) ? parent_alive_interval :
1003                     MIN(deadline, parent_alive_interval);
1004         if (deadline == 0) {
1005                 *tvpp = NULL;
1006         } else {
1007                 tv.tv_sec = deadline;
1008                 tv.tv_usec = 0;
1009                 *tvpp = &tv;
1010         }
1011         return (1);
1012 }
1013
1014 static void
1015 after_select(fd_set *readset, fd_set *writeset)
1016 {
1017         struct sockaddr_un sunaddr;
1018         socklen_t slen;
1019         char buf[1024];
1020         int len, sock;
1021         u_int i, orig_alloc;
1022         uid_t euid;
1023         gid_t egid;
1024
1025         for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++)
1026                 switch (sockets[i].type) {
1027                 case AUTH_UNUSED:
1028                         break;
1029                 case AUTH_SOCKET:
1030                         if (FD_ISSET(sockets[i].fd, readset)) {
1031                                 slen = sizeof(sunaddr);
1032                                 sock = accept(sockets[i].fd,
1033                                     (struct sockaddr *)&sunaddr, &slen);
1034                                 if (sock < 0) {
1035                                         error("accept from AUTH_SOCKET: %s",
1036                                             strerror(errno));
1037                                         break;
1038                                 }
1039                                 if (getpeereid(sock, &euid, &egid) < 0) {
1040                                         error("getpeereid %d failed: %s",
1041                                             sock, strerror(errno));
1042                                         close(sock);
1043                                         break;
1044                                 }
1045                                 if ((euid != 0) && (getuid() != euid)) {
1046                                         error("uid mismatch: "
1047                                             "peer euid %u != uid %u",
1048                                             (u_int) euid, (u_int) getuid());
1049                                         close(sock);
1050                                         break;
1051                                 }
1052                                 new_socket(AUTH_CONNECTION, sock);
1053                         }
1054                         break;
1055                 case AUTH_CONNECTION:
1056                         if (buffer_len(&sockets[i].output) > 0 &&
1057                             FD_ISSET(sockets[i].fd, writeset)) {
1058                                 len = write(sockets[i].fd,
1059                                     buffer_ptr(&sockets[i].output),
1060                                     buffer_len(&sockets[i].output));
1061                                 if (len == -1 && (errno == EAGAIN ||
1062                                     errno == EWOULDBLOCK ||
1063                                     errno == EINTR))
1064                                         continue;
1065                                 if (len <= 0) {
1066                                         close_socket(&sockets[i]);
1067                                         break;
1068                                 }
1069                                 buffer_consume(&sockets[i].output, len);
1070                         }
1071                         if (FD_ISSET(sockets[i].fd, readset)) {
1072                                 len = read(sockets[i].fd, buf, sizeof(buf));
1073                                 if (len == -1 && (errno == EAGAIN ||
1074                                     errno == EWOULDBLOCK ||
1075                                     errno == EINTR))
1076                                         continue;
1077                                 if (len <= 0) {
1078                                         close_socket(&sockets[i]);
1079                                         break;
1080                                 }
1081                                 buffer_append(&sockets[i].input, buf, len);
1082                                 process_message(&sockets[i]);
1083                         }
1084                         break;
1085                 default:
1086                         fatal("Unknown type %d", sockets[i].type);
1087                 }
1088 }
1089
1090 static void
1091 cleanup_socket(void)
1092 {
1093         if (socket_name[0])
1094                 unlink(socket_name);
1095         if (socket_dir[0])
1096                 rmdir(socket_dir);
1097 }
1098
1099 void
1100 cleanup_exit(int i)
1101 {
1102         cleanup_socket();
1103         _exit(i);
1104 }
1105
1106 /*ARGSUSED*/
1107 static void
1108 cleanup_handler(int sig)
1109 {
1110         cleanup_socket();
1111 #ifdef ENABLE_PKCS11
1112         pkcs11_terminate();
1113 #endif
1114         _exit(2);
1115 }
1116
1117 static void
1118 check_parent_exists(void)
1119 {
1120         /*
1121          * If our parent has exited then getppid() will return (pid_t)1,
1122          * so testing for that should be safe.
1123          */
1124         if (parent_pid != -1 && getppid() != parent_pid) {
1125                 /* printf("Parent has died - Authentication agent exiting.\n"); */
1126                 cleanup_socket();
1127                 _exit(2);
1128         }
1129 }
1130
1131 static void
1132 usage(void)
1133 {
1134         fprintf(stderr, "usage: %s [options] [command [arg ...]]\n",
1135             __progname);
1136         fprintf(stderr, "Options:\n");
1137         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1138         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1139         fprintf(stderr, "  -k          Kill the current agent.\n");
1140         fprintf(stderr, "  -d          Debug mode.\n");
1141         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1142         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1143         fprintf(stderr, "  -x          Exit when the last client disconnects.\n");
1144         exit(1);
1145 }
1146
1147 int
1148 main(int ac, char **av)
1149 {
1150         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1151         int sock, fd, ch, result, saved_errno;
1152         u_int nalloc;
1153         char *shell, *format, *pidstr, *agentsocket = NULL;
1154         fd_set *readsetp = NULL, *writesetp = NULL;
1155         struct sockaddr_un sunaddr;
1156 #ifdef HAVE_SETRLIMIT
1157         struct rlimit rlim;
1158 #endif
1159         int prev_mask;
1160         extern int optind;
1161         extern char *optarg;
1162         pid_t pid;
1163         char pidstrbuf[1 + 3 * sizeof pid];
1164         struct timeval *tvp = NULL;
1165         size_t len;
1166
1167         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1168         sanitise_stdfd();
1169
1170         /* drop */
1171         setegid(getgid());
1172         setgid(getgid());
1173         setuid(geteuid());
1174
1175 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1176         /* Disable ptrace on Linux without sgid bit */
1177         prctl(PR_SET_DUMPABLE, 0);
1178 #endif
1179
1180         OpenSSL_add_all_algorithms();
1181
1182         __progname = ssh_get_progname(av[0]);
1183         seed_rng();
1184
1185         while ((ch = getopt(ac, av, "cdksa:t:x")) != -1) {
1186                 switch (ch) {
1187                 case 'c':
1188                         if (s_flag)
1189                                 usage();
1190                         c_flag++;
1191                         break;
1192                 case 'k':
1193                         k_flag++;
1194                         break;
1195                 case 's':
1196                         if (c_flag)
1197                                 usage();
1198                         s_flag++;
1199                         break;
1200                 case 'd':
1201                         if (d_flag)
1202                                 usage();
1203                         d_flag++;
1204                         break;
1205                 case 'a':
1206                         agentsocket = optarg;
1207                         break;
1208                 case 't':
1209                         if ((lifetime = convtime(optarg)) == -1) {
1210                                 fprintf(stderr, "Invalid lifetime\n");
1211                                 usage();
1212                         }
1213                         break;
1214                 case 'x':
1215                         xcount = 0;
1216                         break;
1217                 default:
1218                         usage();
1219                 }
1220         }
1221         ac -= optind;
1222         av += optind;
1223
1224         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1225                 usage();
1226
1227         if (ac == 0 && !c_flag && !s_flag) {
1228                 shell = getenv("SHELL");
1229                 if (shell != NULL && (len = strlen(shell)) > 2 &&
1230                     strncmp(shell + len - 3, "csh", 3) == 0)
1231                         c_flag = 1;
1232         }
1233         if (k_flag) {
1234                 const char *errstr = NULL;
1235
1236                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1237                 if (pidstr == NULL) {
1238                         fprintf(stderr, "%s not set, cannot kill agent\n",
1239                             SSH_AGENTPID_ENV_NAME);
1240                         exit(1);
1241                 }
1242                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1243                 if (errstr) {
1244                         fprintf(stderr,
1245                             "%s=\"%s\", which is not a good PID: %s\n",
1246                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1247                         exit(1);
1248                 }
1249                 if (kill(pid, SIGTERM) == -1) {
1250                         perror("kill");
1251                         exit(1);
1252                 }
1253                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1254                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1255                 printf(format, SSH_AGENTPID_ENV_NAME);
1256                 printf("echo Agent pid %ld killed;\n", (long)pid);
1257                 exit(0);
1258         }
1259         parent_pid = getpid();
1260
1261         if (agentsocket == NULL) {
1262                 /* Create private directory for agent socket */
1263                 mktemp_proto(socket_dir, sizeof(socket_dir));
1264                 if (mkdtemp(socket_dir) == NULL) {
1265                         perror("mkdtemp: private socket dir");
1266                         exit(1);
1267                 }
1268                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1269                     (long)parent_pid);
1270         } else {
1271                 /* Try to use specified agent socket */
1272                 socket_dir[0] = '\0';
1273                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1274         }
1275
1276         /*
1277          * Create socket early so it will exist before command gets run from
1278          * the parent.
1279          */
1280         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1281         if (sock < 0) {
1282                 perror("socket");
1283                 *socket_name = '\0'; /* Don't unlink any existing file */
1284                 cleanup_exit(1);
1285         }
1286         memset(&sunaddr, 0, sizeof(sunaddr));
1287         sunaddr.sun_family = AF_UNIX;
1288         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1289         prev_mask = umask(0177);
1290         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1291                 perror("bind");
1292                 *socket_name = '\0'; /* Don't unlink any existing file */
1293                 umask(prev_mask);
1294                 cleanup_exit(1);
1295         }
1296         umask(prev_mask);
1297         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1298                 perror("listen");
1299                 cleanup_exit(1);
1300         }
1301
1302         /*
1303          * Fork, and have the parent execute the command, if any, or present
1304          * the socket data.  The child continues as the authentication agent.
1305          */
1306         if (d_flag) {
1307                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1308                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1309                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1310                     SSH_AUTHSOCKET_ENV_NAME);
1311                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1312                 goto skip;
1313         }
1314         pid = fork();
1315         if (pid == -1) {
1316                 perror("fork");
1317                 cleanup_exit(1);
1318         }
1319         if (pid != 0) {         /* Parent - execute the given command. */
1320                 close(sock);
1321                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1322                 if (ac == 0) {
1323                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1324                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1325                             SSH_AUTHSOCKET_ENV_NAME);
1326                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1327                             SSH_AGENTPID_ENV_NAME);
1328                         printf("echo Agent pid %ld;\n", (long)pid);
1329                         exit(0);
1330                 }
1331                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1332                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1333                         perror("setenv");
1334                         exit(1);
1335                 }
1336                 execvp(av[0], av);
1337                 perror(av[0]);
1338                 exit(1);
1339         }
1340         /* child */
1341         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1342
1343         if (setsid() == -1) {
1344                 error("setsid: %s", strerror(errno));
1345                 cleanup_exit(1);
1346         }
1347
1348         (void)chdir("/");
1349         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1350                 /* XXX might close listen socket */
1351                 (void)dup2(fd, STDIN_FILENO);
1352                 (void)dup2(fd, STDOUT_FILENO);
1353                 (void)dup2(fd, STDERR_FILENO);
1354                 if (fd > 2)
1355                         close(fd);
1356         }
1357
1358 #ifdef HAVE_SETRLIMIT
1359         /* deny core dumps, since memory contains unencrypted private keys */
1360         rlim.rlim_cur = rlim.rlim_max = 0;
1361         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1362                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1363                 cleanup_exit(1);
1364         }
1365 #endif
1366
1367 skip:
1368
1369 #ifdef ENABLE_PKCS11
1370         pkcs11_init(0);
1371 #endif
1372         new_socket(AUTH_SOCKET, sock);
1373         if (ac > 0)
1374                 parent_alive_interval = 10;
1375         idtab_init();
1376         signal(SIGPIPE, SIG_IGN);
1377         signal(SIGINT, d_flag ? cleanup_handler : SIG_IGN);
1378         signal(SIGHUP, cleanup_handler);
1379         signal(SIGTERM, cleanup_handler);
1380         nalloc = 0;
1381
1382         while (1) {
1383                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1384                 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1385                 saved_errno = errno;
1386                 if (parent_alive_interval != 0)
1387                         check_parent_exists();
1388                 (void) reaper();        /* remove expired keys */
1389                 if (result < 0) {
1390                         if (saved_errno == EINTR)
1391                                 continue;
1392                         fatal("select: %s", strerror(saved_errno));
1393                 } else if (result > 0)
1394                         after_select(readsetp, writesetp);
1395         }
1396         /* NOTREACHED */
1397 }