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