ssh-agent.c

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