ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.171 2010/11/21 01:01:13 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
  39 #include <sys/types.h>
  40 #include <sys/param.h>
  41 #include <sys/resource.h>
  42 #include <sys/stat.h>
  43 #include <sys/socket.h>
  44 #ifdef HAVE_SYS_TIME_H
  45 # include <sys/time.h>
  46 #endif
  47 #ifdef HAVE_SYS_UN_H
  48 # include <sys/un.h>
  49 #endif
  50 #include "openbsd-compat/sys-queue.h"
  51
  52 #include <openssl/evp.h>
  53 #include <openssl/md5.h>
  54 #include "openbsd-compat/openssl-compat.h"
  55
  56 #include <errno.h>
  57 #include <fcntl.h>
  58 #ifdef HAVE_PATHS_H
  59 # include <paths.h>
  60 #endif
  61 #include <signal.h>
  62 #include <stdarg.h>
  63 #include <stdio.h>
  64 #include <stdlib.h>
  65 #include <time.h>
  66 #include <string.h>
  67 #include <unistd.h>
  68
  69 #include "xmalloc.h"
  70 #include "ssh.h"
  71 #include "rsa.h"
  72 #include "buffer.h"
  73 #include "key.h"
  74 #include "authfd.h"
  75 #include "compat.h"
  76 #include "log.h"
  77 #include "misc.h"
  78
  79 #ifdef ENABLE_PKCS11
  80 #include "ssh-pkcs11.h"
  81 #endif
  82
  83 #if defined(HAVE_SYS_PRCTL_H)
  84 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  85 #endif
  86
  87 typedef enum {
  88         AUTH_UNUSED,
  89         AUTH_SOCKET,
  90         AUTH_CONNECTION
  91 } sock_type;
  92
  93 typedef struct {
  94         int fd;
  95         sock_type type;
  96         Buffer input;
  97         Buffer output;
  98         Buffer request;
  99 } SocketEntry;
 100
 101 u_int sockets_alloc = 0;
 102 SocketEntry *sockets = NULL;
 103
 104 typedef struct identity {
 105         TAILQ_ENTRY(identity) next;
 106         Key *key;
 107         char *comment;
 108         char *provider;
 109         u_int death;
 110         u_int confirm;
 111 } Identity;
 112
 113 typedef struct {
 114         int nentries;
 115         TAILQ_HEAD(idqueue, identity) idlist;
 116 } Idtab;
 117
 118 /* private key table, one per protocol version */
 119 Idtab idtable[3];
 120
 121 int max_fd = 0;
 122
 123 /* pid of shell == parent of agent */
 124 pid_t parent_pid = -1;
 125 u_int parent_alive_interval = 0;
 126
 127 /* pathname and directory for AUTH_SOCKET */
 128 char socket_name[MAXPATHLEN];
 129 char socket_dir[MAXPATHLEN];
 130
 131 /* locking */
 132 int locked = 0;
 133 char *lock_passwd = NULL;
 134
 135 extern char *__progname;
 136
 137 /* Default lifetime (0 == forever) */
 138 static int lifetime = 0;
 139
 140 static void
 141 close_socket(SocketEntry *e)
 142 {
 143         close(e->fd);
 144         e->fd = -1;
 145         e->type = AUTH_UNUSED;
 146         buffer_free(&e->input);
 147         buffer_free(&e->output);
 148         buffer_free(&e->request);
 149 }
 150
 151 static void
 152 idtab_init(void)
 153 {
 154         int i;
 155
 156         for (i = 0; i <=2; i++) {
 157                 TAILQ_INIT(&idtable[i].idlist);
 158                 idtable[i].nentries = 0;
 159         }
 160 }
 161
 162 /* return private key table for requested protocol version */
 163 static Idtab *
 164 idtab_lookup(int version)
 165 {
 166         if (version < 1 || version > 2)
 167                 fatal("internal error, bad protocol version %d", version);
 168         return &idtable[version];
 169 }
 170
 171 static void
 172 free_identity(Identity *id)
 173 {
 174         key_free(id->key);
 175         if (id->provider != NULL)
 176                 xfree(id->provider);
 177         xfree(id->comment);
 178         xfree(id);
 179 }
 180
 181 /* return matching private key for given public key */
 182 static Identity *
 183 lookup_identity(Key *key, int version)
 184 {
 185         Identity *id;
 186
 187         Idtab *tab = idtab_lookup(version);
 188         TAILQ_FOREACH(id, &tab->idlist, next) {
 189                 if (key_equal(key, id->key))
 190                         return (id);
 191         }
 192         return (NULL);
 193 }
 194
 195 /* Check confirmation of keysign request */
 196 static int
 197 confirm_key(Identity *id)
 198 {
 199         char *p;
 200         int ret = -1;
 201
 202         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 203         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 204             id->comment, p))
 205                 ret = 0;
 206         xfree(p);
 207
 208         return (ret);
 209 }
 210
 211 /* send list of supported public keys to 'client' */
 212 static void
 213 process_request_identities(SocketEntry *e, int version)
 214 {
 215         Idtab *tab = idtab_lookup(version);
 216         Identity *id;
 217         Buffer msg;
 218
 219         buffer_init(&msg);
 220         buffer_put_char(&msg, (version == 1) ?
 221             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 222         buffer_put_int(&msg, tab->nentries);
 223         TAILQ_FOREACH(id, &tab->idlist, next) {
 224                 if (id->key->type == KEY_RSA1) {
 225                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 226                         buffer_put_bignum(&msg, id->key->rsa->e);
 227                         buffer_put_bignum(&msg, id->key->rsa->n);
 228                 } else {
 229                         u_char *blob;
 230                         u_int blen;
 231                         key_to_blob(id->key, &blob, &blen);
 232                         buffer_put_string(&msg, blob, blen);
 233                         xfree(blob);
 234                 }
 235                 buffer_put_cstring(&msg, id->comment);
 236         }
 237         buffer_put_int(&e->output, buffer_len(&msg));
 238         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 239         buffer_free(&msg);
 240 }
 241
 242 /* ssh1 only */
 243 static void
 244 process_authentication_challenge1(SocketEntry *e)
 245 {
 246         u_char buf[32], mdbuf[16], session_id[16];
 247         u_int response_type;
 248         BIGNUM *challenge;
 249         Identity *id;
 250         int i, len;
 251         Buffer msg;
 252         MD5_CTX md;
 253         Key *key;
 254
 255         buffer_init(&msg);
 256         key = key_new(KEY_RSA1);
 257         if ((challenge = BN_new()) == NULL)
 258                 fatal("process_authentication_challenge1: BN_new failed");
 259
 260         (void) buffer_get_int(&e->request);                     /* ignored */
 261         buffer_get_bignum(&e->request, key->rsa->e);
 262         buffer_get_bignum(&e->request, key->rsa->n);
 263         buffer_get_bignum(&e->request, challenge);
 264
 265         /* Only protocol 1.1 is supported */
 266         if (buffer_len(&e->request) == 0)
 267                 goto failure;
 268         buffer_get(&e->request, session_id, 16);
 269         response_type = buffer_get_int(&e->request);
 270         if (response_type != 1)
 271                 goto failure;
 272
 273         id = lookup_identity(key, 1);
 274         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 275                 Key *private = id->key;
 276                 /* Decrypt the challenge using the private key. */
 277                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 278                         goto failure;
 279
 280                 /* The response is MD5 of decrypted challenge plus session id. */
 281                 len = BN_num_bytes(challenge);
 282                 if (len <= 0 || len > 32) {
 283                         logit("process_authentication_challenge: bad challenge length %d", len);
 284                         goto failure;
 285                 }
 286                 memset(buf, 0, 32);
 287                 BN_bn2bin(challenge, buf + 32 - len);
 288                 MD5_Init(&md);
 289                 MD5_Update(&md, buf, 32);
 290                 MD5_Update(&md, session_id, 16);
 291                 MD5_Final(mdbuf, &md);
 292
 293                 /* Send the response. */
 294                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 295                 for (i = 0; i < 16; i++)
 296                         buffer_put_char(&msg, mdbuf[i]);
 297                 goto send;
 298         }
 299
 300 failure:
 301         /* Unknown identity or protocol error.  Send failure. */
 302         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 303 send:
 304         buffer_put_int(&e->output, buffer_len(&msg));
 305         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 306         key_free(key);
 307         BN_clear_free(challenge);
 308         buffer_free(&msg);
 309 }
 310
 311 /* ssh2 only */
 312 static void
 313 process_sign_request2(SocketEntry *e)
 314 {
 315         u_char *blob, *data, *signature = NULL;
 316         u_int blen, dlen, slen = 0;
 317         extern int datafellows;
 318         int odatafellows;
 319         int ok = -1, flags;
 320         Buffer msg;
 321         Key *key;
 322
 323         datafellows = 0;
 324
 325         blob = buffer_get_string(&e->request, &blen);
 326         data = buffer_get_string(&e->request, &dlen);
 327
 328         flags = buffer_get_int(&e->request);
 329         odatafellows = datafellows;
 330         if (flags & SSH_AGENT_OLD_SIGNATURE)
 331                 datafellows = SSH_BUG_SIGBLOB;
 332
 333         key = key_from_blob(blob, blen);
 334         if (key != NULL) {
 335                 Identity *id = lookup_identity(key, 2);
 336                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 337                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 338                 key_free(key);
 339         }
 340         buffer_init(&msg);
 341         if (ok == 0) {
 342                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 343                 buffer_put_string(&msg, signature, slen);
 344         } else {
 345                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 346         }
 347         buffer_put_int(&e->output, buffer_len(&msg));
 348         buffer_append(&e->output, buffer_ptr(&msg),
 349             buffer_len(&msg));
 350         buffer_free(&msg);
 351         xfree(data);
 352         xfree(blob);
 353         if (signature != NULL)
 354                 xfree(signature);
 355         datafellows = odatafellows;
 356 }
 357
 358 /* shared */
 359 static void
 360 process_remove_identity(SocketEntry *e, int version)
 361 {
 362         u_int blen, bits;
 363         int success = 0;
 364         Key *key = NULL;
 365         u_char *blob;
 366
 367         switch (version) {
 368         case 1:
 369                 key = key_new(KEY_RSA1);
 370                 bits = buffer_get_int(&e->request);
 371                 buffer_get_bignum(&e->request, key->rsa->e);
 372                 buffer_get_bignum(&e->request, key->rsa->n);
 373
 374                 if (bits != key_size(key))
 375                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 376                             key_size(key), bits);
 377                 break;
 378         case 2:
 379                 blob = buffer_get_string(&e->request, &blen);
 380                 key = key_from_blob(blob, blen);
 381                 xfree(blob);
 382                 break;
 383         }
 384         if (key != NULL) {
 385                 Identity *id = lookup_identity(key, version);
 386                 if (id != NULL) {
 387                         /*
 388                          * We have this key.  Free the old key.  Since we
 389                          * don't want to leave empty slots in the middle of
 390                          * the array, we actually free the key there and move
 391                          * all the entries between the empty slot and the end
 392                          * of the array.
 393                          */
 394                         Idtab *tab = idtab_lookup(version);
 395                         if (tab->nentries < 1)
 396                                 fatal("process_remove_identity: "
 397                                     "internal error: tab->nentries %d",
 398                                     tab->nentries);
 399                         TAILQ_REMOVE(&tab->idlist, id, next);
 400                         free_identity(id);
 401                         tab->nentries--;
 402                         success = 1;
 403                 }
 404                 key_free(key);
 405         }
 406         buffer_put_int(&e->output, 1);
 407         buffer_put_char(&e->output,
 408             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 409 }
 410
 411 static void
 412 process_remove_all_identities(SocketEntry *e, int version)
 413 {
 414         Idtab *tab = idtab_lookup(version);
 415         Identity *id;
 416
 417         /* Loop over all identities and clear the keys. */
 418         for (id = TAILQ_FIRST(&tab->idlist); id;
 419             id = TAILQ_FIRST(&tab->idlist)) {
 420                 TAILQ_REMOVE(&tab->idlist, id, next);
 421                 free_identity(id);
 422         }
 423
 424         /* Mark that there are no identities. */
 425         tab->nentries = 0;
 426
 427         /* Send success. */
 428         buffer_put_int(&e->output, 1);
 429         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 430 }
 431
 432 /* removes expired keys and returns number of seconds until the next expiry */
 433 static u_int
 434 reaper(void)
 435 {
 436         u_int deadline = 0, now = time(NULL);
 437         Identity *id, *nxt;
 438         int version;
 439         Idtab *tab;
 440
 441         for (version = 1; version < 3; version++) {
 442                 tab = idtab_lookup(version);
 443                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 444                         nxt = TAILQ_NEXT(id, next);
 445                         if (id->death == 0)
 446                                 continue;
 447                         if (now >= id->death) {
 448                                 debug("expiring key '%s'", id->comment);
 449                                 TAILQ_REMOVE(&tab->idlist, id, next);
 450                                 free_identity(id);
 451                                 tab->nentries--;
 452                         } else
 453                                 deadline = (deadline == 0) ? id->death :
 454                                     MIN(deadline, id->death);
 455                 }
 456         }
 457         if (deadline == 0 || deadline <= now)
 458                 return 0;
 459         else
 460                 return (deadline - now);
 461 }
 462
 463 static void
 464 process_add_identity(SocketEntry *e, int version)
 465 {
 466         Idtab *tab = idtab_lookup(version);
 467         Identity *id;
 468         int type, success = 0, death = 0, confirm = 0;
 469         char *type_name, *comment;
 470         Key *k = NULL;
 471 #ifdef OPENSSL_HAS_ECC
 472         BIGNUM *exponent;
 473         EC_POINT *q;
 474         char *curve;
 475 #endif
 476         u_char *cert;
 477         u_int len;
 478
 479         switch (version) {
 480         case 1:
 481                 k = key_new_private(KEY_RSA1);
 482                 (void) buffer_get_int(&e->request);             /* ignored */
 483                 buffer_get_bignum(&e->request, k->rsa->n);
 484                 buffer_get_bignum(&e->request, k->rsa->e);
 485                 buffer_get_bignum(&e->request, k->rsa->d);
 486                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 487
 488                 /* SSH and SSL have p and q swapped */
 489                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 490                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 491
 492                 /* Generate additional parameters */
 493                 rsa_generate_additional_parameters(k->rsa);
 494                 break;
 495         case 2:
 496                 type_name = buffer_get_string(&e->request, NULL);
 497                 type = key_type_from_name(type_name);
 498                 switch (type) {
 499                 case KEY_DSA:
 500                         k = key_new_private(type);
 501                         buffer_get_bignum2(&e->request, k->dsa->p);
 502                         buffer_get_bignum2(&e->request, k->dsa->q);
 503                         buffer_get_bignum2(&e->request, k->dsa->g);
 504                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 505                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 506                         break;
 507                 case KEY_DSA_CERT_V00:
 508                 case KEY_DSA_CERT:
 509                         cert = buffer_get_string(&e->request, &len);
 510                         if ((k = key_from_blob(cert, len)) == NULL)
 511                                 fatal("Certificate parse failed");
 512                         xfree(cert);
 513                         key_add_private(k);
 514                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 515                         break;
 516 #ifdef OPENSSL_HAS_ECC
 517                 case KEY_ECDSA:
 518                         k = key_new_private(type);
 519                         k->ecdsa_nid = key_ecdsa_nid_from_name(type_name);
 520                         curve = buffer_get_string(&e->request, NULL);
 521                         if (k->ecdsa_nid != key_curve_name_to_nid(curve))
 522                                 fatal("%s: curve names mismatch", __func__);
 523                         xfree(curve);
 524                         k->ecdsa = EC_KEY_new_by_curve_name(k->ecdsa_nid);
 525                         if (k->ecdsa == NULL)
 526                                 fatal("%s: EC_KEY_new_by_curve_name failed",
 527                                     __func__);
 528                         q = EC_POINT_new(EC_KEY_get0_group(k->ecdsa));
 529                         if (q == NULL)
 530                                 fatal("%s: BN_new failed", __func__);
 531                         if ((exponent = BN_new()) == NULL)
 532                                 fatal("%s: BN_new failed", __func__);
 533                         buffer_get_ecpoint(&e->request,
 534                                 EC_KEY_get0_group(k->ecdsa), q);
 535                         buffer_get_bignum2(&e->request, exponent);
 536                         if (EC_KEY_set_public_key(k->ecdsa, q) != 1)
 537                                 fatal("%s: EC_KEY_set_public_key failed",
 538                                     __func__);
 539                         if (EC_KEY_set_private_key(k->ecdsa, exponent) != 1)
 540                                 fatal("%s: EC_KEY_set_private_key failed",
 541                                     __func__);
 542                         if (key_ec_validate_public(EC_KEY_get0_group(k->ecdsa),
 543                             EC_KEY_get0_public_key(k->ecdsa)) != 0)
 544                                 fatal("%s: bad ECDSA public key", __func__);
 545                         if (key_ec_validate_private(k->ecdsa) != 0)
 546                                 fatal("%s: bad ECDSA private key", __func__);
 547                         BN_clear_free(exponent);
 548                         EC_POINT_free(q);
 549                         break;
 550                 case KEY_ECDSA_CERT:
 551                         cert = buffer_get_string(&e->request, &len);
 552                         if ((k = key_from_blob(cert, len)) == NULL)
 553                                 fatal("Certificate parse failed");
 554                         xfree(cert);
 555                         key_add_private(k);
 556                         if ((exponent = BN_new()) == NULL)
 557                                 fatal("%s: BN_new failed", __func__);
 558                         buffer_get_bignum2(&e->request, exponent);
 559                         if (EC_KEY_set_private_key(k->ecdsa, exponent) != 1)
 560                                 fatal("%s: EC_KEY_set_private_key failed",
 561                                     __func__);
 562                         if (key_ec_validate_public(EC_KEY_get0_group(k->ecdsa),
 563                             EC_KEY_get0_public_key(k->ecdsa)) != 0 ||
 564                             key_ec_validate_private(k->ecdsa) != 0)
 565                                 fatal("%s: bad ECDSA key", __func__);
 566                         BN_clear_free(exponent);
 567                         break;
 568 #endif /* OPENSSL_HAS_ECC */
 569                 case KEY_RSA:
 570                         k = key_new_private(type);
 571                         buffer_get_bignum2(&e->request, k->rsa->n);
 572                         buffer_get_bignum2(&e->request, k->rsa->e);
 573                         buffer_get_bignum2(&e->request, k->rsa->d);
 574                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 575                         buffer_get_bignum2(&e->request, k->rsa->p);
 576                         buffer_get_bignum2(&e->request, k->rsa->q);
 577
 578                         /* Generate additional parameters */
 579                         rsa_generate_additional_parameters(k->rsa);
 580                         break;
 581                 case KEY_RSA_CERT_V00:
 582                 case KEY_RSA_CERT:
 583                         cert = buffer_get_string(&e->request, &len);
 584                         if ((k = key_from_blob(cert, len)) == NULL)
 585                                 fatal("Certificate parse failed");
 586                         xfree(cert);
 587                         key_add_private(k);
 588                         buffer_get_bignum2(&e->request, k->rsa->d);
 589                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 590                         buffer_get_bignum2(&e->request, k->rsa->p);
 591                         buffer_get_bignum2(&e->request, k->rsa->q);
 592                         break;
 593                 default:
 594                         xfree(type_name);
 595                         buffer_clear(&e->request);
 596                         goto send;
 597                 }
 598                 xfree(type_name);
 599                 break;
 600         }
 601         /* enable blinding */
 602         switch (k->type) {
 603         case KEY_RSA:
 604         case KEY_RSA_CERT_V00:
 605         case KEY_RSA_CERT:
 606         case KEY_RSA1:
 607                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 608                         error("process_add_identity: RSA_blinding_on failed");
 609                         key_free(k);
 610                         goto send;
 611                 }
 612                 break;
 613         }
 614         comment = buffer_get_string(&e->request, NULL);
 615         if (k == NULL) {
 616                 xfree(comment);
 617                 goto send;
 618         }
 619         while (buffer_len(&e->request)) {
 620                 switch ((type = buffer_get_char(&e->request))) {
 621                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 622                         death = time(NULL) + buffer_get_int(&e->request);
 623                         break;
 624                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 625                         confirm = 1;
 626                         break;
 627                 default:
 628                         error("process_add_identity: "
 629                             "Unknown constraint type %d", type);
 630                         xfree(comment);
 631                         key_free(k);
 632                         goto send;
 633                 }
 634         }
 635         success = 1;
 636         if (lifetime && !death)
 637                 death = time(NULL) + lifetime;
 638         if ((id = lookup_identity(k, version)) == NULL) {
 639                 id = xcalloc(1, sizeof(Identity));
 640                 id->key = k;
 641                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 642                 /* Increment the number of identities. */
 643                 tab->nentries++;
 644         } else {
 645                 key_free(k);
 646                 xfree(id->comment);
 647         }
 648         id->comment = comment;
 649         id->death = death;
 650         id->confirm = confirm;
 651 send:
 652         buffer_put_int(&e->output, 1);
 653         buffer_put_char(&e->output,
 654             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 655 }
 656
 657 /* XXX todo: encrypt sensitive data with passphrase */
 658 static void
 659 process_lock_agent(SocketEntry *e, int lock)
 660 {
 661         int success = 0;
 662         char *passwd;
 663
 664         passwd = buffer_get_string(&e->request, NULL);
 665         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 666                 locked = 0;
 667                 memset(lock_passwd, 0, strlen(lock_passwd));
 668                 xfree(lock_passwd);
 669                 lock_passwd = NULL;
 670                 success = 1;
 671         } else if (!locked && lock) {
 672                 locked = 1;
 673                 lock_passwd = xstrdup(passwd);
 674                 success = 1;
 675         }
 676         memset(passwd, 0, strlen(passwd));
 677         xfree(passwd);
 678
 679         buffer_put_int(&e->output, 1);
 680         buffer_put_char(&e->output,
 681             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 682 }
 683
 684 static void
 685 no_identities(SocketEntry *e, u_int type)
 686 {
 687         Buffer msg;
 688
 689         buffer_init(&msg);
 690         buffer_put_char(&msg,
 691             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 692             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 693         buffer_put_int(&msg, 0);
 694         buffer_put_int(&e->output, buffer_len(&msg));
 695         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 696         buffer_free(&msg);
 697 }
 698
 699 #ifdef ENABLE_PKCS11
 700 static void
 701 process_add_smartcard_key(SocketEntry *e)
 702 {
 703         char *provider = NULL, *pin;
 704         int i, type, version, count = 0, success = 0, death = 0, confirm = 0;
 705         Key **keys = NULL, *k;
 706         Identity *id;
 707         Idtab *tab;
 708
 709         provider = buffer_get_string(&e->request, NULL);
 710         pin = buffer_get_string(&e->request, NULL);
 711
 712         while (buffer_len(&e->request)) {
 713                 switch ((type = buffer_get_char(&e->request))) {
 714                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 715                         death = time(NULL) + buffer_get_int(&e->request);
 716                         break;
 717                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 718                         confirm = 1;
 719                         break;
 720                 default:
 721                         error("process_add_smartcard_key: "
 722                             "Unknown constraint type %d", type);
 723                         goto send;
 724                 }
 725         }
 726         if (lifetime && !death)
 727                 death = time(NULL) + lifetime;
 728
 729         count = pkcs11_add_provider(provider, pin, &keys);
 730         for (i = 0; i < count; i++) {
 731                 k = keys[i];
 732                 version = k->type == KEY_RSA1 ? 1 : 2;
 733                 tab = idtab_lookup(version);
 734                 if (lookup_identity(k, version) == NULL) {
 735                         id = xcalloc(1, sizeof(Identity));
 736                         id->key = k;
 737                         id->provider = xstrdup(provider);
 738                         id->comment = xstrdup(provider); /* XXX */
 739                         id->death = death;
 740                         id->confirm = confirm;
 741                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 742                         tab->nentries++;
 743                         success = 1;
 744                 } else {
 745                         key_free(k);
 746                 }
 747                 keys[i] = NULL;
 748         }
 749 send:
 750         if (pin)
 751                 xfree(pin);
 752         if (provider)
 753                 xfree(provider);
 754         if (keys)
 755                 xfree(keys);
 756         buffer_put_int(&e->output, 1);
 757         buffer_put_char(&e->output,
 758             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 759 }
 760
 761 static void
 762 process_remove_smartcard_key(SocketEntry *e)
 763 {
 764         char *provider = NULL, *pin = NULL;
 765         int version, success = 0;
 766         Identity *id, *nxt;
 767         Idtab *tab;
 768
 769         provider = buffer_get_string(&e->request, NULL);
 770         pin = buffer_get_string(&e->request, NULL);
 771         xfree(pin);
 772
 773         for (version = 1; version < 3; version++) {
 774                 tab = idtab_lookup(version);
 775                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 776                         nxt = TAILQ_NEXT(id, next);
 777                         if (!strcmp(provider, id->provider)) {
 778                                 TAILQ_REMOVE(&tab->idlist, id, next);
 779                                 free_identity(id);
 780                                 tab->nentries--;
 781                         }
 782                 }
 783         }
 784         if (pkcs11_del_provider(provider) == 0)
 785                 success = 1;
 786         else
 787                 error("process_remove_smartcard_key:"
 788                     " pkcs11_del_provider failed");
 789         xfree(provider);
 790         buffer_put_int(&e->output, 1);
 791         buffer_put_char(&e->output,
 792             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 793 }
 794 #endif /* ENABLE_PKCS11 */
 795
 796 /* dispatch incoming messages */
 797
 798 static void
 799 process_message(SocketEntry *e)
 800 {
 801         u_int msg_len, type;
 802         u_char *cp;
 803
 804         if (buffer_len(&e->input) < 5)
 805                 return;         /* Incomplete message. */
 806         cp = buffer_ptr(&e->input);
 807         msg_len = get_u32(cp);
 808         if (msg_len > 256 * 1024) {
 809                 close_socket(e);
 810                 return;
 811         }
 812         if (buffer_len(&e->input) < msg_len + 4)
 813                 return;
 814
 815         /* move the current input to e->request */
 816         buffer_consume(&e->input, 4);
 817         buffer_clear(&e->request);
 818         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 819         buffer_consume(&e->input, msg_len);
 820         type = buffer_get_char(&e->request);
 821
 822         /* check wheter agent is locked */
 823         if (locked && type != SSH_AGENTC_UNLOCK) {
 824                 buffer_clear(&e->request);
 825                 switch (type) {
 826                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 827                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 828                         /* send empty lists */
 829                         no_identities(e, type);
 830                         break;
 831                 default:
 832                         /* send a fail message for all other request types */
 833                         buffer_put_int(&e->output, 1);
 834                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 835                 }
 836                 return;
 837         }
 838
 839         debug("type %d", type);
 840         switch (type) {
 841         case SSH_AGENTC_LOCK:
 842         case SSH_AGENTC_UNLOCK:
 843                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 844                 break;
 845         /* ssh1 */
 846         case SSH_AGENTC_RSA_CHALLENGE:
 847                 process_authentication_challenge1(e);
 848                 break;
 849         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 850                 process_request_identities(e, 1);
 851                 break;
 852         case SSH_AGENTC_ADD_RSA_IDENTITY:
 853         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 854                 process_add_identity(e, 1);
 855                 break;
 856         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 857                 process_remove_identity(e, 1);
 858                 break;
 859         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 860                 process_remove_all_identities(e, 1);
 861                 break;
 862         /* ssh2 */
 863         case SSH2_AGENTC_SIGN_REQUEST:
 864                 process_sign_request2(e);
 865                 break;
 866         case SSH2_AGENTC_REQUEST_IDENTITIES:
 867                 process_request_identities(e, 2);
 868                 break;
 869         case SSH2_AGENTC_ADD_IDENTITY:
 870         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 871                 process_add_identity(e, 2);
 872                 break;
 873         case SSH2_AGENTC_REMOVE_IDENTITY:
 874                 process_remove_identity(e, 2);
 875                 break;
 876         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 877                 process_remove_all_identities(e, 2);
 878                 break;
 879 #ifdef ENABLE_PKCS11
 880         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 881         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 882                 process_add_smartcard_key(e);
 883                 break;
 884         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 885                 process_remove_smartcard_key(e);
 886                 break;
 887 #endif /* ENABLE_PKCS11 */
 888         default:
 889                 /* Unknown message.  Respond with failure. */
 890                 error("Unknown message %d", type);
 891                 buffer_clear(&e->request);
 892                 buffer_put_int(&e->output, 1);
 893                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 894                 break;
 895         }
 896 }
 897
 898 static void
 899 new_socket(sock_type type, int fd)
 900 {
 901         u_int i, old_alloc, new_alloc;
 902
 903         set_nonblock(fd);
 904
 905         if (fd > max_fd)
 906                 max_fd = fd;
 907
 908         for (i = 0; i < sockets_alloc; i++)
 909                 if (sockets[i].type == AUTH_UNUSED) {
 910                         sockets[i].fd = fd;
 911                         buffer_init(&sockets[i].input);
 912                         buffer_init(&sockets[i].output);
 913                         buffer_init(&sockets[i].request);
 914                         sockets[i].type = type;
 915                         return;
 916                 }
 917         old_alloc = sockets_alloc;
 918         new_alloc = sockets_alloc + 10;
 919         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 920         for (i = old_alloc; i < new_alloc; i++)
 921                 sockets[i].type = AUTH_UNUSED;
 922         sockets_alloc = new_alloc;
 923         sockets[old_alloc].fd = fd;
 924         buffer_init(&sockets[old_alloc].input);
 925         buffer_init(&sockets[old_alloc].output);
 926         buffer_init(&sockets[old_alloc].request);
 927         sockets[old_alloc].type = type;
 928 }
 929
 930 static int
 931 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
 932     struct timeval **tvpp)
 933 {
 934         u_int i, sz, deadline;
 935         int n = 0;
 936         static struct timeval tv;
 937
 938         for (i = 0; i < sockets_alloc; i++) {
 939                 switch (sockets[i].type) {
 940                 case AUTH_SOCKET:
 941                 case AUTH_CONNECTION:
 942                         n = MAX(n, sockets[i].fd);
 943                         break;
 944                 case AUTH_UNUSED:
 945                         break;
 946                 default:
 947                         fatal("Unknown socket type %d", sockets[i].type);
 948                         break;
 949                 }
 950         }
 951
 952         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 953         if (*fdrp == NULL || sz > *nallocp) {
 954                 if (*fdrp)
 955                         xfree(*fdrp);
 956                 if (*fdwp)
 957                         xfree(*fdwp);
 958                 *fdrp = xmalloc(sz);
 959                 *fdwp = xmalloc(sz);
 960                 *nallocp = sz;
 961         }
 962         if (n < *fdl)
 963                 debug("XXX shrink: %d < %d", n, *fdl);
 964         *fdl = n;
 965         memset(*fdrp, 0, sz);
 966         memset(*fdwp, 0, sz);
 967
 968         for (i = 0; i < sockets_alloc; i++) {
 969                 switch (sockets[i].type) {
 970                 case AUTH_SOCKET:
 971                 case AUTH_CONNECTION:
 972                         FD_SET(sockets[i].fd, *fdrp);
 973                         if (buffer_len(&sockets[i].output) > 0)
 974                                 FD_SET(sockets[i].fd, *fdwp);
 975                         break;
 976                 default:
 977                         break;
 978                 }
 979         }
 980         deadline = reaper();
 981         if (parent_alive_interval != 0)
 982                 deadline = (deadline == 0) ? parent_alive_interval :
 983                     MIN(deadline, parent_alive_interval);
 984         if (deadline == 0) {
 985                 *tvpp = NULL;
 986         } else {
 987                 tv.tv_sec = deadline;
 988                 tv.tv_usec = 0;
 989                 *tvpp = &tv;
 990         }
 991         return (1);
 992 }
 993
 994 static void
 995 after_select(fd_set *readset, fd_set *writeset)
 996 {
 997         struct sockaddr_un sunaddr;
 998         socklen_t slen;
 999         char buf[1024];
1000         int len, sock;
1001         u_int i, orig_alloc;
1002         uid_t euid;
1003         gid_t egid;
1004
1005         for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++)
1006                 switch (sockets[i].type) {
1007                 case AUTH_UNUSED:
1008                         break;
1009                 case AUTH_SOCKET:
1010                         if (FD_ISSET(sockets[i].fd, readset)) {
1011                                 slen = sizeof(sunaddr);
1012                                 sock = accept(sockets[i].fd,
1013                                     (struct sockaddr *)&sunaddr, &slen);
1014                                 if (sock < 0) {
1015                                         error("accept from AUTH_SOCKET: %s",
1016                                             strerror(errno));
1017                                         break;
1018                                 }
1019                                 if (getpeereid(sock, &euid, &egid) < 0) {
1020                                         error("getpeereid %d failed: %s",
1021                                             sock, strerror(errno));
1022                                         close(sock);
1023                                         break;
1024                                 }
1025                                 if ((euid != 0) && (getuid() != euid)) {
1026                                         error("uid mismatch: "
1027                                             "peer euid %u != uid %u",
1028                                             (u_int) euid, (u_int) getuid());
1029                                         close(sock);
1030                                         break;
1031                                 }
1032                                 new_socket(AUTH_CONNECTION, sock);
1033                         }
1034                         break;
1035                 case AUTH_CONNECTION:
1036                         if (buffer_len(&sockets[i].output) > 0 &&
1037                             FD_ISSET(sockets[i].fd, writeset)) {
1038                                 len = write(sockets[i].fd,
1039                                     buffer_ptr(&sockets[i].output),
1040                                     buffer_len(&sockets[i].output));
1041                                 if (len == -1 && (errno == EAGAIN ||
1042                                     errno == EWOULDBLOCK ||
1043                                     errno == EINTR))
1044                                         continue;
1045                                 if (len <= 0) {
1046                                         close_socket(&sockets[i]);
1047                                         break;
1048                                 }
1049                                 buffer_consume(&sockets[i].output, len);
1050                         }
1051                         if (FD_ISSET(sockets[i].fd, readset)) {
1052                                 len = read(sockets[i].fd, buf, sizeof(buf));
1053                                 if (len == -1 && (errno == EAGAIN ||
1054                                     errno == EWOULDBLOCK ||
1055                                     errno == EINTR))
1056                                         continue;
1057                                 if (len <= 0) {
1058                                         close_socket(&sockets[i]);
1059                                         break;
1060                                 }
1061                                 buffer_append(&sockets[i].input, buf, len);
1062                                 process_message(&sockets[i]);
1063                         }
1064                         break;
1065                 default:
1066                         fatal("Unknown type %d", sockets[i].type);
1067                 }
1068 }
1069
1070 static void
1071 cleanup_socket(void)
1072 {
1073         if (socket_name[0])
1074                 unlink(socket_name);
1075         if (socket_dir[0])
1076                 rmdir(socket_dir);
1077 }
1078
1079 void
1080 cleanup_exit(int i)
1081 {
1082         cleanup_socket();
1083         _exit(i);
1084 }
1085
1086 /*ARGSUSED*/
1087 static void
1088 cleanup_handler(int sig)
1089 {
1090         cleanup_socket();
1091 #ifdef ENABLE_PKCS11
1092         pkcs11_terminate();
1093 #endif
1094         _exit(2);
1095 }
1096
1097 static void
1098 check_parent_exists(void)
1099 {
1100         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
1101                 /* printf("Parent has died - Authentication agent exiting.\n"); */
1102                 cleanup_socket();
1103                 _exit(2);
1104         }
1105 }
1106
1107 static void
1108 usage(void)
1109 {
1110         fprintf(stderr, "usage: %s [options] [command [arg ...]]\n",
1111             __progname);
1112         fprintf(stderr, "Options:\n");
1113         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1114         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1115         fprintf(stderr, "  -k          Kill the current agent.\n");
1116         fprintf(stderr, "  -d          Debug mode.\n");
1117         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1118         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1119         exit(1);
1120 }
1121
1122 int
1123 main(int ac, char **av)
1124 {
1125         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1126         int sock, fd, ch, result, saved_errno;
1127         u_int nalloc;
1128         char *shell, *format, *pidstr, *agentsocket = NULL;
1129         fd_set *readsetp = NULL, *writesetp = NULL;
1130         struct sockaddr_un sunaddr;
1131 #ifdef HAVE_SETRLIMIT
1132         struct rlimit rlim;
1133 #endif
1134         int prev_mask;
1135         extern int optind;
1136         extern char *optarg;
1137         pid_t pid;
1138         char pidstrbuf[1 + 3 * sizeof pid];
1139         struct timeval *tvp = NULL;
1140         size_t len;
1141
1142         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1143         sanitise_stdfd();
1144
1145         /* drop */
1146         setegid(getgid());
1147         setgid(getgid());
1148
1149 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1150         /* Disable ptrace on Linux without sgid bit */
1151         prctl(PR_SET_DUMPABLE, 0);
1152 #endif
1153
1154         OpenSSL_add_all_algorithms();
1155
1156         __progname = ssh_get_progname(av[0]);
1157         init_rng();
1158         seed_rng();
1159
1160         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1161                 switch (ch) {
1162                 case 'c':
1163                         if (s_flag)
1164                                 usage();
1165                         c_flag++;
1166                         break;
1167                 case 'k':
1168                         k_flag++;
1169                         break;
1170                 case 's':
1171                         if (c_flag)
1172                                 usage();
1173                         s_flag++;
1174                         break;
1175                 case 'd':
1176                         if (d_flag)
1177                                 usage();
1178                         d_flag++;
1179                         break;
1180                 case 'a':
1181                         agentsocket = optarg;
1182                         break;
1183                 case 't':
1184                         if ((lifetime = convtime(optarg)) == -1) {
1185                                 fprintf(stderr, "Invalid lifetime\n");
1186                                 usage();
1187                         }
1188                         break;
1189                 default:
1190                         usage();
1191                 }
1192         }
1193         ac -= optind;
1194         av += optind;
1195
1196         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1197                 usage();
1198
1199         if (ac == 0 && !c_flag && !s_flag) {
1200                 shell = getenv("SHELL");
1201                 if (shell != NULL && (len = strlen(shell)) > 2 &&
1202                     strncmp(shell + len - 3, "csh", 3) == 0)
1203                         c_flag = 1;
1204         }
1205         if (k_flag) {
1206                 const char *errstr = NULL;
1207
1208                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1209                 if (pidstr == NULL) {
1210                         fprintf(stderr, "%s not set, cannot kill agent\n",
1211                             SSH_AGENTPID_ENV_NAME);
1212                         exit(1);
1213                 }
1214                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1215                 if (errstr) {
1216                         fprintf(stderr,
1217                             "%s=\"%s\", which is not a good PID: %s\n",
1218                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1219                         exit(1);
1220                 }
1221                 if (kill(pid, SIGTERM) == -1) {
1222                         perror("kill");
1223                         exit(1);
1224                 }
1225                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1226                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1227                 printf(format, SSH_AGENTPID_ENV_NAME);
1228                 printf("echo Agent pid %ld killed;\n", (long)pid);
1229                 exit(0);
1230         }
1231         parent_pid = getpid();
1232
1233         if (agentsocket == NULL) {
1234                 /* Create private directory for agent socket */
1235                 mktemp_proto(socket_dir, sizeof(socket_dir));
1236                 if (mkdtemp(socket_dir) == NULL) {
1237                         perror("mkdtemp: private socket dir");
1238                         exit(1);
1239                 }
1240                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1241                     (long)parent_pid);
1242         } else {
1243                 /* Try to use specified agent socket */
1244                 socket_dir[0] = '\0';
1245                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1246         }
1247
1248         /*
1249          * Create socket early so it will exist before command gets run from
1250          * the parent.
1251          */
1252         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1253         if (sock < 0) {
1254                 perror("socket");
1255                 *socket_name = '\0'; /* Don't unlink any existing file */
1256                 cleanup_exit(1);
1257         }
1258         memset(&sunaddr, 0, sizeof(sunaddr));
1259         sunaddr.sun_family = AF_UNIX;
1260         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1261         prev_mask = umask(0177);
1262         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1263                 perror("bind");
1264                 *socket_name = '\0'; /* Don't unlink any existing file */
1265                 umask(prev_mask);
1266                 cleanup_exit(1);
1267         }
1268         umask(prev_mask);
1269         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1270                 perror("listen");
1271                 cleanup_exit(1);
1272         }
1273
1274         /*
1275          * Fork, and have the parent execute the command, if any, or present
1276          * the socket data.  The child continues as the authentication agent.
1277          */
1278         if (d_flag) {
1279                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1280                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1281                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1282                     SSH_AUTHSOCKET_ENV_NAME);
1283                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1284                 goto skip;
1285         }
1286         pid = fork();
1287         if (pid == -1) {
1288                 perror("fork");
1289                 cleanup_exit(1);
1290         }
1291         if (pid != 0) {         /* Parent - execute the given command. */
1292                 close(sock);
1293                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1294                 if (ac == 0) {
1295                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1296                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1297                             SSH_AUTHSOCKET_ENV_NAME);
1298                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1299                             SSH_AGENTPID_ENV_NAME);
1300                         printf("echo Agent pid %ld;\n", (long)pid);
1301                         exit(0);
1302                 }
1303                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1304                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1305                         perror("setenv");
1306                         exit(1);
1307                 }
1308                 execvp(av[0], av);
1309                 perror(av[0]);
1310                 exit(1);
1311         }
1312         /* child */
1313         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1314
1315         if (setsid() == -1) {
1316                 error("setsid: %s", strerror(errno));
1317                 cleanup_exit(1);
1318         }
1319
1320         (void)chdir("/");
1321         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1322                 /* XXX might close listen socket */
1323                 (void)dup2(fd, STDIN_FILENO);
1324                 (void)dup2(fd, STDOUT_FILENO);
1325                 (void)dup2(fd, STDERR_FILENO);
1326                 if (fd > 2)
1327                         close(fd);
1328         }
1329
1330 #ifdef HAVE_SETRLIMIT
1331         /* deny core dumps, since memory contains unencrypted private keys */
1332         rlim.rlim_cur = rlim.rlim_max = 0;
1333         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1334                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1335                 cleanup_exit(1);
1336         }
1337 #endif
1338
1339 skip:
1340
1341 #ifdef ENABLE_PKCS11
1342         pkcs11_init(0);
1343 #endif
1344         new_socket(AUTH_SOCKET, sock);
1345         if (ac > 0)
1346                 parent_alive_interval = 10;
1347         idtab_init();
1348         if (!d_flag)
1349                 signal(SIGINT, SIG_IGN);
1350         signal(SIGPIPE, SIG_IGN);
1351         signal(SIGHUP, cleanup_handler);
1352         signal(SIGTERM, cleanup_handler);
1353         nalloc = 0;
1354
1355         while (1) {
1356                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1357                 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1358                 saved_errno = errno;
1359                 if (parent_alive_interval != 0)
1360                         check_parent_exists();
1361                 (void) reaper();        /* remove expired keys */
1362                 if (result < 0) {
1363                         if (saved_errno == EINTR)
1364                                 continue;
1365                         fatal("select: %s", strerror(saved_errno));
1366                 } else if (result > 0)
1367                         after_select(readsetp, writesetp);
1368         }
1369         /* NOTREACHED */
1370 }