crypto/openssh/ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.183 2014/02/02 03:44:31 djm Exp $ */
   2 /* $FreeBSD$ */
   3 /*
   4  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   5  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   6  *                    All rights reserved
   7  * The authentication agent program.
   8  *
   9  * As far as I am concerned, the code I have written for this software
  10  * can be used freely for any purpose.  Any derived versions of this
  11  * software must be clearly marked as such, and if the derived work is
  12  * incompatible with the protocol description in the RFC file, it must be
  13  * called by a name other than "ssh" or "Secure Shell".
  14  *
  15  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  16  *
  17  * Redistribution and use in source and binary forms, with or without
  18  * modification, are permitted provided that the following conditions
  19  * are met:
  20  * 1. Redistributions of source code must retain the above copyright
  21  *    notice, this list of conditions and the following disclaimer.
  22  * 2. Redistributions in binary form must reproduce the above copyright
  23  *    notice, this list of conditions and the following disclaimer in the
  24  *    documentation and/or other materials provided with the distribution.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  27  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  29  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  30  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  31  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  35  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  */
  37
  38 #include "includes.h"
  39 __RCSID("$FreeBSD$");
  40
  41 #include <sys/types.h>
  42 #include <sys/param.h>
  43 #include <sys/resource.h>
  44 #include <sys/stat.h>
  45 #include <sys/socket.h>
  46 #ifdef HAVE_SYS_TIME_H
  47 # include <sys/time.h>
  48 #endif
  49 #ifdef HAVE_SYS_UN_H
  50 # include <sys/un.h>
  51 #endif
  52 #include "openbsd-compat/sys-queue.h"
  53
  54 #include <openssl/evp.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 #include "digest.h"
  80
  81 #ifdef ENABLE_PKCS11
  82 #include "ssh-pkcs11.h"
  83 #endif
  84
  85 #if defined(HAVE_SYS_PRCTL_H)
  86 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  87 #endif
  88
  89 typedef enum {
  90         AUTH_UNUSED,
  91         AUTH_SOCKET,
  92         AUTH_CONNECTION
  93 } sock_type;
  94
  95 typedef struct {
  96         int fd;
  97         sock_type type;
  98         Buffer input;
  99         Buffer output;
 100         Buffer request;
 101 } SocketEntry;
 102
 103 u_int sockets_alloc = 0;
 104 SocketEntry *sockets = NULL;
 105
 106 typedef struct identity {
 107         TAILQ_ENTRY(identity) next;
 108         Key *key;
 109         char *comment;
 110         char *provider;
 111         time_t death;
 112         u_int confirm;
 113 } Identity;
 114
 115 typedef struct {
 116         int nentries;
 117         TAILQ_HEAD(idqueue, identity) idlist;
 118 } Idtab;
 119
 120 /* private key table, one per protocol version */
 121 Idtab idtable[3];
 122
 123 int max_fd = 0;
 124
 125 /* pid of shell == parent of agent */
 126 pid_t parent_pid = -1;
 127 time_t parent_alive_interval = 0;
 128
 129 /* pathname and directory for AUTH_SOCKET */
 130 char socket_name[MAXPATHLEN];
 131 char socket_dir[MAXPATHLEN];
 132
 133 /* locking */
 134 int locked = 0;
 135 char *lock_passwd = NULL;
 136
 137 extern char *__progname;
 138
 139 /* Default lifetime in seconds (0 == forever) */
 140 static long lifetime = 0;
 141
 142 /*
 143  * Client connection count; incremented in new_socket() and decremented in
 144  * close_socket().  When it reaches 0, ssh-agent will exit.  Since it is
 145  * normally initialized to 1, it will never reach 0.  However, if the -x
 146  * option is specified, it is initialized to 0 in main(); in that case,
 147  * ssh-agent will exit as soon as it has had at least one client but no
 148  * longer has any.
 149  */
 150 static int xcount = 1;
 151
 152 static void
 153 close_socket(SocketEntry *e)
 154 {
 155         int last = 0;
 156
 157         if (e->type == AUTH_CONNECTION) {
 158                 debug("xcount %d -> %d", xcount, xcount - 1);
 159                 if (--xcount == 0)
 160                         last = 1;
 161         }
 162         close(e->fd);
 163         e->fd = -1;
 164         e->type = AUTH_UNUSED;
 165         buffer_free(&e->input);
 166         buffer_free(&e->output);
 167         buffer_free(&e->request);
 168         if (last)
 169                 cleanup_exit(0);
 170 }
 171
 172 static void
 173 idtab_init(void)
 174 {
 175         int i;
 176
 177         for (i = 0; i <=2; i++) {
 178                 TAILQ_INIT(&idtable[i].idlist);
 179                 idtable[i].nentries = 0;
 180         }
 181 }
 182
 183 /* return private key table for requested protocol version */
 184 static Idtab *
 185 idtab_lookup(int version)
 186 {
 187         if (version < 1 || version > 2)
 188                 fatal("internal error, bad protocol version %d", version);
 189         return &idtable[version];
 190 }
 191
 192 static void
 193 free_identity(Identity *id)
 194 {
 195         key_free(id->key);
 196         free(id->provider);
 197         free(id->comment);
 198         free(id);
 199 }
 200
 201 /* return matching private key for given public key */
 202 static Identity *
 203 lookup_identity(Key *key, int version)
 204 {
 205         Identity *id;
 206
 207         Idtab *tab = idtab_lookup(version);
 208         TAILQ_FOREACH(id, &tab->idlist, next) {
 209                 if (key_equal(key, id->key))
 210                         return (id);
 211         }
 212         return (NULL);
 213 }
 214
 215 /* Check confirmation of keysign request */
 216 static int
 217 confirm_key(Identity *id)
 218 {
 219         char *p;
 220         int ret = -1;
 221
 222         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 223         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 224             id->comment, p))
 225                 ret = 0;
 226         free(p);
 227
 228         return (ret);
 229 }
 230
 231 /* send list of supported public keys to 'client' */
 232 static void
 233 process_request_identities(SocketEntry *e, int version)
 234 {
 235         Idtab *tab = idtab_lookup(version);
 236         Identity *id;
 237         Buffer msg;
 238
 239         buffer_init(&msg);
 240         buffer_put_char(&msg, (version == 1) ?
 241             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 242         buffer_put_int(&msg, tab->nentries);
 243         TAILQ_FOREACH(id, &tab->idlist, next) {
 244                 if (id->key->type == KEY_RSA1) {
 245                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 246                         buffer_put_bignum(&msg, id->key->rsa->e);
 247                         buffer_put_bignum(&msg, id->key->rsa->n);
 248                 } else {
 249                         u_char *blob;
 250                         u_int blen;
 251                         key_to_blob(id->key, &blob, &blen);
 252                         buffer_put_string(&msg, blob, blen);
 253                         free(blob);
 254                 }
 255                 buffer_put_cstring(&msg, id->comment);
 256         }
 257         buffer_put_int(&e->output, buffer_len(&msg));
 258         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 259         buffer_free(&msg);
 260 }
 261
 262 /* ssh1 only */
 263 static void
 264 process_authentication_challenge1(SocketEntry *e)
 265 {
 266         u_char buf[32], mdbuf[16], session_id[16];
 267         u_int response_type;
 268         BIGNUM *challenge;
 269         Identity *id;
 270         int i, len;
 271         Buffer msg;
 272         struct ssh_digest_ctx *md;
 273         Key *key;
 274
 275         buffer_init(&msg);
 276         key = key_new(KEY_RSA1);
 277         if ((challenge = BN_new()) == NULL)
 278                 fatal("process_authentication_challenge1: BN_new failed");
 279
 280         (void) buffer_get_int(&e->request);                     /* ignored */
 281         buffer_get_bignum(&e->request, key->rsa->e);
 282         buffer_get_bignum(&e->request, key->rsa->n);
 283         buffer_get_bignum(&e->request, challenge);
 284
 285         /* Only protocol 1.1 is supported */
 286         if (buffer_len(&e->request) == 0)
 287                 goto failure;
 288         buffer_get(&e->request, session_id, 16);
 289         response_type = buffer_get_int(&e->request);
 290         if (response_type != 1)
 291                 goto failure;
 292
 293         id = lookup_identity(key, 1);
 294         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 295                 Key *private = id->key;
 296                 /* Decrypt the challenge using the private key. */
 297                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 298                         goto failure;
 299
 300                 /* The response is MD5 of decrypted challenge plus session id. */
 301                 len = BN_num_bytes(challenge);
 302                 if (len <= 0 || len > 32) {
 303                         logit("process_authentication_challenge: bad challenge length %d", len);
 304                         goto failure;
 305                 }
 306                 memset(buf, 0, 32);
 307                 BN_bn2bin(challenge, buf + 32 - len);
 308                 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL ||
 309                     ssh_digest_update(md, buf, 32) < 0 ||
 310                     ssh_digest_update(md, session_id, 16) < 0 ||
 311                     ssh_digest_final(md, mdbuf, sizeof(mdbuf)) < 0)
 312                         fatal("%s: md5 failed", __func__);
 313                 ssh_digest_free(md);
 314
 315                 /* Send the response. */
 316                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 317                 for (i = 0; i < 16; i++)
 318                         buffer_put_char(&msg, mdbuf[i]);
 319                 goto send;
 320         }
 321
 322 failure:
 323         /* Unknown identity or protocol error.  Send failure. */
 324         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 325 send:
 326         buffer_put_int(&e->output, buffer_len(&msg));
 327         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 328         key_free(key);
 329         BN_clear_free(challenge);
 330         buffer_free(&msg);
 331 }
 332
 333 /* ssh2 only */
 334 static void
 335 process_sign_request2(SocketEntry *e)
 336 {
 337         u_char *blob, *data, *signature = NULL;
 338         u_int blen, dlen, slen = 0;
 339         extern int datafellows;
 340         int odatafellows;
 341         int ok = -1, flags;
 342         Buffer msg;
 343         Key *key;
 344
 345         datafellows = 0;
 346
 347         blob = buffer_get_string(&e->request, &blen);
 348         data = buffer_get_string(&e->request, &dlen);
 349
 350         flags = buffer_get_int(&e->request);
 351         odatafellows = datafellows;
 352         if (flags & SSH_AGENT_OLD_SIGNATURE)
 353                 datafellows = SSH_BUG_SIGBLOB;
 354
 355         key = key_from_blob(blob, blen);
 356         if (key != NULL) {
 357                 Identity *id = lookup_identity(key, 2);
 358                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 359                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 360                 key_free(key);
 361         }
 362         buffer_init(&msg);
 363         if (ok == 0) {
 364                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 365                 buffer_put_string(&msg, signature, slen);
 366         } else {
 367                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 368         }
 369         buffer_put_int(&e->output, buffer_len(&msg));
 370         buffer_append(&e->output, buffer_ptr(&msg),
 371             buffer_len(&msg));
 372         buffer_free(&msg);
 373         free(data);
 374         free(blob);
 375         free(signature);
 376         datafellows = odatafellows;
 377 }
 378
 379 /* shared */
 380 static void
 381 process_remove_identity(SocketEntry *e, int version)
 382 {
 383         u_int blen, bits;
 384         int success = 0;
 385         Key *key = NULL;
 386         u_char *blob;
 387
 388         switch (version) {
 389         case 1:
 390                 key = key_new(KEY_RSA1);
 391                 bits = buffer_get_int(&e->request);
 392                 buffer_get_bignum(&e->request, key->rsa->e);
 393                 buffer_get_bignum(&e->request, key->rsa->n);
 394
 395                 if (bits != key_size(key))
 396                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 397                             key_size(key), bits);
 398                 break;
 399         case 2:
 400                 blob = buffer_get_string(&e->request, &blen);
 401                 key = key_from_blob(blob, blen);
 402                 free(blob);
 403                 break;
 404         }
 405         if (key != NULL) {
 406                 Identity *id = lookup_identity(key, version);
 407                 if (id != NULL) {
 408                         /*
 409                          * We have this key.  Free the old key.  Since we
 410                          * don't want to leave empty slots in the middle of
 411                          * the array, we actually free the key there and move
 412                          * all the entries between the empty slot and the end
 413                          * of the array.
 414                          */
 415                         Idtab *tab = idtab_lookup(version);
 416                         if (tab->nentries < 1)
 417                                 fatal("process_remove_identity: "
 418                                     "internal error: tab->nentries %d",
 419                                     tab->nentries);
 420                         TAILQ_REMOVE(&tab->idlist, id, next);
 421                         free_identity(id);
 422                         tab->nentries--;
 423                         success = 1;
 424                 }
 425                 key_free(key);
 426         }
 427         buffer_put_int(&e->output, 1);
 428         buffer_put_char(&e->output,
 429             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 430 }
 431
 432 static void
 433 process_remove_all_identities(SocketEntry *e, int version)
 434 {
 435         Idtab *tab = idtab_lookup(version);
 436         Identity *id;
 437
 438         /* Loop over all identities and clear the keys. */
 439         for (id = TAILQ_FIRST(&tab->idlist); id;
 440             id = TAILQ_FIRST(&tab->idlist)) {
 441                 TAILQ_REMOVE(&tab->idlist, id, next);
 442                 free_identity(id);
 443         }
 444
 445         /* Mark that there are no identities. */
 446         tab->nentries = 0;
 447
 448         /* Send success. */
 449         buffer_put_int(&e->output, 1);
 450         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 451 }
 452
 453 /* removes expired keys and returns number of seconds until the next expiry */
 454 static time_t
 455 reaper(void)
 456 {
 457         time_t deadline = 0, now = monotime();
 458         Identity *id, *nxt;
 459         int version;
 460         Idtab *tab;
 461
 462         for (version = 1; version < 3; version++) {
 463                 tab = idtab_lookup(version);
 464                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 465                         nxt = TAILQ_NEXT(id, next);
 466                         if (id->death == 0)
 467                                 continue;
 468                         if (now >= id->death) {
 469                                 debug("expiring key '%s'", id->comment);
 470                                 TAILQ_REMOVE(&tab->idlist, id, next);
 471                                 free_identity(id);
 472                                 tab->nentries--;
 473                         } else
 474                                 deadline = (deadline == 0) ? id->death :
 475                                     MIN(deadline, id->death);
 476                 }
 477         }
 478         if (deadline == 0 || deadline <= now)
 479                 return 0;
 480         else
 481                 return (deadline - now);
 482 }
 483
 484 static void
 485 process_add_identity(SocketEntry *e, int version)
 486 {
 487         Idtab *tab = idtab_lookup(version);
 488         Identity *id;
 489         int type, success = 0, confirm = 0;
 490         char *comment;
 491         time_t death = 0;
 492         Key *k = NULL;
 493
 494         switch (version) {
 495         case 1:
 496                 k = key_new_private(KEY_RSA1);
 497                 (void) buffer_get_int(&e->request);             /* ignored */
 498                 buffer_get_bignum(&e->request, k->rsa->n);
 499                 buffer_get_bignum(&e->request, k->rsa->e);
 500                 buffer_get_bignum(&e->request, k->rsa->d);
 501                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 502
 503                 /* SSH and SSL have p and q swapped */
 504                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 505                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 506
 507                 /* Generate additional parameters */
 508                 rsa_generate_additional_parameters(k->rsa);
 509
 510                 /* enable blinding */
 511                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 512                         error("process_add_identity: RSA_blinding_on failed");
 513                         key_free(k);
 514                         goto send;
 515                 }
 516                 break;
 517         case 2:
 518                 k = key_private_deserialize(&e->request);
 519                 if (k == NULL) {
 520                         buffer_clear(&e->request);
 521                         goto send;
 522                 }
 523                 break;
 524         }
 525         comment = buffer_get_string(&e->request, NULL);
 526         if (k == NULL) {
 527                 free(comment);
 528                 goto send;
 529         }
 530         while (buffer_len(&e->request)) {
 531                 switch ((type = buffer_get_char(&e->request))) {
 532                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 533                         death = monotime() + buffer_get_int(&e->request);
 534                         break;
 535                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 536                         confirm = 1;
 537                         break;
 538                 default:
 539                         error("process_add_identity: "
 540                             "Unknown constraint type %d", type);
 541                         free(comment);
 542                         key_free(k);
 543                         goto send;
 544                 }
 545         }
 546         success = 1;
 547         if (lifetime && !death)
 548                 death = monotime() + lifetime;
 549         if ((id = lookup_identity(k, version)) == NULL) {
 550                 id = xcalloc(1, sizeof(Identity));
 551                 id->key = k;
 552                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 553                 /* Increment the number of identities. */
 554                 tab->nentries++;
 555         } else {
 556                 key_free(k);
 557                 free(id->comment);
 558         }
 559         id->comment = comment;
 560         id->death = death;
 561         id->confirm = confirm;
 562 send:
 563         buffer_put_int(&e->output, 1);
 564         buffer_put_char(&e->output,
 565             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 566 }
 567
 568 /* XXX todo: encrypt sensitive data with passphrase */
 569 static void
 570 process_lock_agent(SocketEntry *e, int lock)
 571 {
 572         int success = 0;
 573         char *passwd;
 574
 575         passwd = buffer_get_string(&e->request, NULL);
 576         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 577                 locked = 0;
 578                 explicit_bzero(lock_passwd, strlen(lock_passwd));
 579                 free(lock_passwd);
 580                 lock_passwd = NULL;
 581                 success = 1;
 582         } else if (!locked && lock) {
 583                 locked = 1;
 584                 lock_passwd = xstrdup(passwd);
 585                 success = 1;
 586         }
 587         explicit_bzero(passwd, strlen(passwd));
 588         free(passwd);
 589
 590         buffer_put_int(&e->output, 1);
 591         buffer_put_char(&e->output,
 592             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 593 }
 594
 595 static void
 596 no_identities(SocketEntry *e, u_int type)
 597 {
 598         Buffer msg;
 599
 600         buffer_init(&msg);
 601         buffer_put_char(&msg,
 602             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 603             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 604         buffer_put_int(&msg, 0);
 605         buffer_put_int(&e->output, buffer_len(&msg));
 606         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 607         buffer_free(&msg);
 608 }
 609
 610 #ifdef ENABLE_PKCS11
 611 static void
 612 process_add_smartcard_key(SocketEntry *e)
 613 {
 614         char *provider = NULL, *pin;
 615         int i, type, version, count = 0, success = 0, confirm = 0;
 616         time_t death = 0;
 617         Key **keys = NULL, *k;
 618         Identity *id;
 619         Idtab *tab;
 620
 621         provider = buffer_get_string(&e->request, NULL);
 622         pin = buffer_get_string(&e->request, NULL);
 623
 624         while (buffer_len(&e->request)) {
 625                 switch ((type = buffer_get_char(&e->request))) {
 626                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 627                         death = monotime() + buffer_get_int(&e->request);
 628                         break;
 629                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 630                         confirm = 1;
 631                         break;
 632                 default:
 633                         error("process_add_smartcard_key: "
 634                             "Unknown constraint type %d", type);
 635                         goto send;
 636                 }
 637         }
 638         if (lifetime && !death)
 639                 death = monotime() + lifetime;
 640
 641         count = pkcs11_add_provider(provider, pin, &keys);
 642         for (i = 0; i < count; i++) {
 643                 k = keys[i];
 644                 version = k->type == KEY_RSA1 ? 1 : 2;
 645                 tab = idtab_lookup(version);
 646                 if (lookup_identity(k, version) == NULL) {
 647                         id = xcalloc(1, sizeof(Identity));
 648                         id->key = k;
 649                         id->provider = xstrdup(provider);
 650                         id->comment = xstrdup(provider); /* XXX */
 651                         id->death = death;
 652                         id->confirm = confirm;
 653                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 654                         tab->nentries++;
 655                         success = 1;
 656                 } else {
 657                         key_free(k);
 658                 }
 659                 keys[i] = NULL;
 660         }
 661 send:
 662         free(pin);
 663         free(provider);
 664         free(keys);
 665         buffer_put_int(&e->output, 1);
 666         buffer_put_char(&e->output,
 667             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 668 }
 669
 670 static void
 671 process_remove_smartcard_key(SocketEntry *e)
 672 {
 673         char *provider = NULL, *pin = NULL;
 674         int version, success = 0;
 675         Identity *id, *nxt;
 676         Idtab *tab;
 677
 678         provider = buffer_get_string(&e->request, NULL);
 679         pin = buffer_get_string(&e->request, NULL);
 680         free(pin);
 681
 682         for (version = 1; version < 3; version++) {
 683                 tab = idtab_lookup(version);
 684                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 685                         nxt = TAILQ_NEXT(id, next);
 686                         /* Skip file--based keys */
 687                         if (id->provider == NULL)
 688                                 continue;
 689                         if (!strcmp(provider, id->provider)) {
 690                                 TAILQ_REMOVE(&tab->idlist, id, next);
 691                                 free_identity(id);
 692                                 tab->nentries--;
 693                         }
 694                 }
 695         }
 696         if (pkcs11_del_provider(provider) == 0)
 697                 success = 1;
 698         else
 699                 error("process_remove_smartcard_key:"
 700                     " pkcs11_del_provider failed");
 701         free(provider);
 702         buffer_put_int(&e->output, 1);
 703         buffer_put_char(&e->output,
 704             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 705 }
 706 #endif /* ENABLE_PKCS11 */
 707
 708 /* dispatch incoming messages */
 709
 710 static void
 711 process_message(SocketEntry *e)
 712 {
 713         u_int msg_len, type;
 714         u_char *cp;
 715
 716         if (buffer_len(&e->input) < 5)
 717                 return;         /* Incomplete message. */
 718         cp = buffer_ptr(&e->input);
 719         msg_len = get_u32(cp);
 720         if (msg_len > 256 * 1024) {
 721                 close_socket(e);
 722                 return;
 723         }
 724         if (buffer_len(&e->input) < msg_len + 4)
 725                 return;
 726
 727         /* move the current input to e->request */
 728         buffer_consume(&e->input, 4);
 729         buffer_clear(&e->request);
 730         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 731         buffer_consume(&e->input, msg_len);
 732         type = buffer_get_char(&e->request);
 733
 734         /* check wheter agent is locked */
 735         if (locked && type != SSH_AGENTC_UNLOCK) {
 736                 buffer_clear(&e->request);
 737                 switch (type) {
 738                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 739                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 740                         /* send empty lists */
 741                         no_identities(e, type);
 742                         break;
 743                 default:
 744                         /* send a fail message for all other request types */
 745                         buffer_put_int(&e->output, 1);
 746                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 747                 }
 748                 return;
 749         }
 750
 751         debug("type %d", type);
 752         switch (type) {
 753         case SSH_AGENTC_LOCK:
 754         case SSH_AGENTC_UNLOCK:
 755                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 756                 break;
 757         /* ssh1 */
 758         case SSH_AGENTC_RSA_CHALLENGE:
 759                 process_authentication_challenge1(e);
 760                 break;
 761         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 762                 process_request_identities(e, 1);
 763                 break;
 764         case SSH_AGENTC_ADD_RSA_IDENTITY:
 765         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 766                 process_add_identity(e, 1);
 767                 break;
 768         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 769                 process_remove_identity(e, 1);
 770                 break;
 771         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 772                 process_remove_all_identities(e, 1);
 773                 break;
 774         /* ssh2 */
 775         case SSH2_AGENTC_SIGN_REQUEST:
 776                 process_sign_request2(e);
 777                 break;
 778         case SSH2_AGENTC_REQUEST_IDENTITIES:
 779                 process_request_identities(e, 2);
 780                 break;
 781         case SSH2_AGENTC_ADD_IDENTITY:
 782         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 783                 process_add_identity(e, 2);
 784                 break;
 785         case SSH2_AGENTC_REMOVE_IDENTITY:
 786                 process_remove_identity(e, 2);
 787                 break;
 788         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 789                 process_remove_all_identities(e, 2);
 790                 break;
 791 #ifdef ENABLE_PKCS11
 792         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 793         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 794                 process_add_smartcard_key(e);
 795                 break;
 796         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 797                 process_remove_smartcard_key(e);
 798                 break;
 799 #endif /* ENABLE_PKCS11 */
 800         default:
 801                 /* Unknown message.  Respond with failure. */
 802                 error("Unknown message %d", type);
 803                 buffer_clear(&e->request);
 804                 buffer_put_int(&e->output, 1);
 805                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 806                 break;
 807         }
 808 }
 809
 810 static void
 811 new_socket(sock_type type, int fd)
 812 {
 813         u_int i, old_alloc, new_alloc;
 814
 815         if (type == AUTH_CONNECTION) {
 816                 debug("xcount %d -> %d", xcount, xcount + 1);
 817                 ++xcount;
 818         }
 819         set_nonblock(fd);
 820
 821         if (fd > max_fd)
 822                 max_fd = fd;
 823
 824         for (i = 0; i < sockets_alloc; i++)
 825                 if (sockets[i].type == AUTH_UNUSED) {
 826                         sockets[i].fd = fd;
 827                         buffer_init(&sockets[i].input);
 828                         buffer_init(&sockets[i].output);
 829                         buffer_init(&sockets[i].request);
 830                         sockets[i].type = type;
 831                         return;
 832                 }
 833         old_alloc = sockets_alloc;
 834         new_alloc = sockets_alloc + 10;
 835         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 836         for (i = old_alloc; i < new_alloc; i++)
 837                 sockets[i].type = AUTH_UNUSED;
 838         sockets_alloc = new_alloc;
 839         sockets[old_alloc].fd = fd;
 840         buffer_init(&sockets[old_alloc].input);
 841         buffer_init(&sockets[old_alloc].output);
 842         buffer_init(&sockets[old_alloc].request);
 843         sockets[old_alloc].type = type;
 844 }
 845
 846 static int
 847 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
 848     struct timeval **tvpp)
 849 {
 850         u_int i, sz;
 851         int n = 0;
 852         static struct timeval tv;
 853         time_t deadline;
 854
 855         for (i = 0; i < sockets_alloc; i++) {
 856                 switch (sockets[i].type) {
 857                 case AUTH_SOCKET:
 858                 case AUTH_CONNECTION:
 859                         n = MAX(n, sockets[i].fd);
 860                         break;
 861                 case AUTH_UNUSED:
 862                         break;
 863                 default:
 864                         fatal("Unknown socket type %d", sockets[i].type);
 865                         break;
 866                 }
 867         }
 868
 869         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 870         if (*fdrp == NULL || sz > *nallocp) {
 871                 free(*fdrp);
 872                 free(*fdwp);
 873                 *fdrp = xmalloc(sz);
 874                 *fdwp = xmalloc(sz);
 875                 *nallocp = sz;
 876         }
 877         if (n < *fdl)
 878                 debug("XXX shrink: %d < %d", n, *fdl);
 879         *fdl = n;
 880         memset(*fdrp, 0, sz);
 881         memset(*fdwp, 0, sz);
 882
 883         for (i = 0; i < sockets_alloc; i++) {
 884                 switch (sockets[i].type) {
 885                 case AUTH_SOCKET:
 886                 case AUTH_CONNECTION:
 887                         FD_SET(sockets[i].fd, *fdrp);
 888                         if (buffer_len(&sockets[i].output) > 0)
 889                                 FD_SET(sockets[i].fd, *fdwp);
 890                         break;
 891                 default:
 892                         break;
 893                 }
 894         }
 895         deadline = reaper();
 896         if (parent_alive_interval != 0)
 897                 deadline = (deadline == 0) ? parent_alive_interval :
 898                     MIN(deadline, parent_alive_interval);
 899         if (deadline == 0) {
 900                 *tvpp = NULL;
 901         } else {
 902                 tv.tv_sec = deadline;
 903                 tv.tv_usec = 0;
 904                 *tvpp = &tv;
 905         }
 906         return (1);
 907 }
 908
 909 static void
 910 after_select(fd_set *readset, fd_set *writeset)
 911 {
 912         struct sockaddr_un sunaddr;
 913         socklen_t slen;
 914         char buf[1024];
 915         int len, sock;
 916         u_int i, orig_alloc;
 917         uid_t euid;
 918         gid_t egid;
 919
 920         for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++)
 921                 switch (sockets[i].type) {
 922                 case AUTH_UNUSED:
 923                         break;
 924                 case AUTH_SOCKET:
 925                         if (FD_ISSET(sockets[i].fd, readset)) {
 926                                 slen = sizeof(sunaddr);
 927                                 sock = accept(sockets[i].fd,
 928                                     (struct sockaddr *)&sunaddr, &slen);
 929                                 if (sock < 0) {
 930                                         error("accept from AUTH_SOCKET: %s",
 931                                             strerror(errno));
 932                                         break;
 933                                 }
 934                                 if (getpeereid(sock, &euid, &egid) < 0) {
 935                                         error("getpeereid %d failed: %s",
 936                                             sock, strerror(errno));
 937                                         close(sock);
 938                                         break;
 939                                 }
 940                                 if ((euid != 0) && (getuid() != euid)) {
 941                                         error("uid mismatch: "
 942                                             "peer euid %u != uid %u",
 943                                             (u_int) euid, (u_int) getuid());
 944                                         close(sock);
 945                                         break;
 946                                 }
 947                                 new_socket(AUTH_CONNECTION, sock);
 948                         }
 949                         break;
 950                 case AUTH_CONNECTION:
 951                         if (buffer_len(&sockets[i].output) > 0 &&
 952                             FD_ISSET(sockets[i].fd, writeset)) {
 953                                 len = write(sockets[i].fd,
 954                                     buffer_ptr(&sockets[i].output),
 955                                     buffer_len(&sockets[i].output));
 956                                 if (len == -1 && (errno == EAGAIN ||
 957                                     errno == EWOULDBLOCK ||
 958                                     errno == EINTR))
 959                                         continue;
 960                                 if (len <= 0) {
 961                                         close_socket(&sockets[i]);
 962                                         break;
 963                                 }
 964                                 buffer_consume(&sockets[i].output, len);
 965                         }
 966                         if (FD_ISSET(sockets[i].fd, readset)) {
 967                                 len = read(sockets[i].fd, buf, sizeof(buf));
 968                                 if (len == -1 && (errno == EAGAIN ||
 969                                     errno == EWOULDBLOCK ||
 970                                     errno == EINTR))
 971                                         continue;
 972                                 if (len <= 0) {
 973                                         close_socket(&sockets[i]);
 974                                         break;
 975                                 }
 976                                 buffer_append(&sockets[i].input, buf, len);
 977                                 process_message(&sockets[i]);
 978                         }
 979                         break;
 980                 default:
 981                         fatal("Unknown type %d", sockets[i].type);
 982                 }
 983 }
 984
 985 static void
 986 cleanup_socket(void)
 987 {
 988         if (socket_name[0])
 989                 unlink(socket_name);
 990         if (socket_dir[0])
 991                 rmdir(socket_dir);
 992 }
 993
 994 void
 995 cleanup_exit(int i)
 996 {
 997         cleanup_socket();
 998         _exit(i);
 999 }
1000
1001 /*ARGSUSED*/
1002 static void
1003 cleanup_handler(int sig)
1004 {
1005         cleanup_socket();
1006 #ifdef ENABLE_PKCS11
1007         pkcs11_terminate();
1008 #endif
1009         _exit(2);
1010 }
1011
1012 static void
1013 check_parent_exists(void)
1014 {
1015         /*
1016          * If our parent has exited then getppid() will return (pid_t)1,
1017          * so testing for that should be safe.
1018          */
1019         if (parent_pid != -1 && getppid() != parent_pid) {
1020                 /* printf("Parent has died - Authentication agent exiting.\n"); */
1021                 cleanup_socket();
1022                 _exit(2);
1023         }
1024 }
1025
1026 static void
1027 usage(void)
1028 {
1029         fprintf(stderr, "usage: %s [options] [command [arg ...]]\n",
1030             __progname);
1031         fprintf(stderr, "Options:\n");
1032         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1033         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1034         fprintf(stderr, "  -k          Kill the current agent.\n");
1035         fprintf(stderr, "  -d          Debug mode.\n");
1036         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1037         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1038         fprintf(stderr, "  -x          Exit when the last client disconnects.\n");
1039         exit(1);
1040 }
1041
1042 int
1043 main(int ac, char **av)
1044 {
1045         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1046         int sock, fd, ch, result, saved_errno;
1047         u_int nalloc;
1048         char *shell, *format, *pidstr, *agentsocket = NULL;
1049         fd_set *readsetp = NULL, *writesetp = NULL;
1050         struct sockaddr_un sunaddr;
1051 #ifdef HAVE_SETRLIMIT
1052         struct rlimit rlim;
1053 #endif
1054         int prev_mask;
1055         extern int optind;
1056         extern char *optarg;
1057         pid_t pid;
1058         char pidstrbuf[1 + 3 * sizeof pid];
1059         struct timeval *tvp = NULL;
1060         size_t len;
1061
1062         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1063         sanitise_stdfd();
1064
1065         /* drop */
1066         setegid(getgid());
1067         setgid(getgid());
1068         setuid(geteuid());
1069
1070 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1071         /* Disable ptrace on Linux without sgid bit */
1072         prctl(PR_SET_DUMPABLE, 0);
1073 #endif
1074
1075         OpenSSL_add_all_algorithms();
1076
1077         __progname = ssh_get_progname(av[0]);
1078         seed_rng();
1079
1080         while ((ch = getopt(ac, av, "cdksa:t:x")) != -1) {
1081                 switch (ch) {
1082                 case 'c':
1083                         if (s_flag)
1084                                 usage();
1085                         c_flag++;
1086                         break;
1087                 case 'k':
1088                         k_flag++;
1089                         break;
1090                 case 's':
1091                         if (c_flag)
1092                                 usage();
1093                         s_flag++;
1094                         break;
1095                 case 'd':
1096                         if (d_flag)
1097                                 usage();
1098                         d_flag++;
1099                         break;
1100                 case 'a':
1101                         agentsocket = optarg;
1102                         break;
1103                 case 't':
1104                         if ((lifetime = convtime(optarg)) == -1) {
1105                                 fprintf(stderr, "Invalid lifetime\n");
1106                                 usage();
1107                         }
1108                         break;
1109                 case 'x':
1110                         xcount = 0;
1111                         break;
1112                 default:
1113                         usage();
1114                 }
1115         }
1116         ac -= optind;
1117         av += optind;
1118
1119         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1120                 usage();
1121
1122         if (ac == 0 && !c_flag && !s_flag) {
1123                 shell = getenv("SHELL");
1124                 if (shell != NULL && (len = strlen(shell)) > 2 &&
1125                     strncmp(shell + len - 3, "csh", 3) == 0)
1126                         c_flag = 1;
1127         }
1128         if (k_flag) {
1129                 const char *errstr = NULL;
1130
1131                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1132                 if (pidstr == NULL) {
1133                         fprintf(stderr, "%s not set, cannot kill agent\n",
1134                             SSH_AGENTPID_ENV_NAME);
1135                         exit(1);
1136                 }
1137                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1138                 if (errstr) {
1139                         fprintf(stderr,
1140                             "%s=\"%s\", which is not a good PID: %s\n",
1141                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1142                         exit(1);
1143                 }
1144                 if (kill(pid, SIGTERM) == -1) {
1145                         perror("kill");
1146                         exit(1);
1147                 }
1148                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1149                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1150                 printf(format, SSH_AGENTPID_ENV_NAME);
1151                 printf("echo Agent pid %ld killed;\n", (long)pid);
1152                 exit(0);
1153         }
1154         parent_pid = getpid();
1155
1156         if (agentsocket == NULL) {
1157                 /* Create private directory for agent socket */
1158                 mktemp_proto(socket_dir, sizeof(socket_dir));
1159                 if (mkdtemp(socket_dir) == NULL) {
1160                         perror("mkdtemp: private socket dir");
1161                         exit(1);
1162                 }
1163                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1164                     (long)parent_pid);
1165         } else {
1166                 /* Try to use specified agent socket */
1167                 socket_dir[0] = '\0';
1168                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1169         }
1170
1171         /*
1172          * Create socket early so it will exist before command gets run from
1173          * the parent.
1174          */
1175         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1176         if (sock < 0) {
1177                 perror("socket");
1178                 *socket_name = '\0'; /* Don't unlink any existing file */
1179                 cleanup_exit(1);
1180         }
1181         memset(&sunaddr, 0, sizeof(sunaddr));
1182         sunaddr.sun_family = AF_UNIX;
1183         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1184         prev_mask = umask(0177);
1185         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1186                 perror("bind");
1187                 *socket_name = '\0'; /* Don't unlink any existing file */
1188                 umask(prev_mask);
1189                 cleanup_exit(1);
1190         }
1191         umask(prev_mask);
1192         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1193                 perror("listen");
1194                 cleanup_exit(1);
1195         }
1196
1197         /*
1198          * Fork, and have the parent execute the command, if any, or present
1199          * the socket data.  The child continues as the authentication agent.
1200          */
1201         if (d_flag) {
1202                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1203                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1204                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1205                     SSH_AUTHSOCKET_ENV_NAME);
1206                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1207                 goto skip;
1208         }
1209         pid = fork();
1210         if (pid == -1) {
1211                 perror("fork");
1212                 cleanup_exit(1);
1213         }
1214         if (pid != 0) {         /* Parent - execute the given command. */
1215                 close(sock);
1216                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1217                 if (ac == 0) {
1218                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1219                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1220                             SSH_AUTHSOCKET_ENV_NAME);
1221                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1222                             SSH_AGENTPID_ENV_NAME);
1223                         printf("echo Agent pid %ld;\n", (long)pid);
1224                         exit(0);
1225                 }
1226                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1227                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1228                         perror("setenv");
1229                         exit(1);
1230                 }
1231                 execvp(av[0], av);
1232                 perror(av[0]);
1233                 exit(1);
1234         }
1235         /* child */
1236         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1237
1238         if (setsid() == -1) {
1239                 error("setsid: %s", strerror(errno));
1240                 cleanup_exit(1);
1241         }
1242
1243         (void)chdir("/");
1244         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1245                 /* XXX might close listen socket */
1246                 (void)dup2(fd, STDIN_FILENO);
1247                 (void)dup2(fd, STDOUT_FILENO);
1248                 (void)dup2(fd, STDERR_FILENO);
1249                 if (fd > 2)
1250                         close(fd);
1251         }
1252
1253 #ifdef HAVE_SETRLIMIT
1254         /* deny core dumps, since memory contains unencrypted private keys */
1255         rlim.rlim_cur = rlim.rlim_max = 0;
1256         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1257                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1258                 cleanup_exit(1);
1259         }
1260 #endif
1261
1262 skip:
1263
1264 #ifdef ENABLE_PKCS11
1265         pkcs11_init(0);
1266 #endif
1267         new_socket(AUTH_SOCKET, sock);
1268         if (ac > 0)
1269                 parent_alive_interval = 10;
1270         idtab_init();
1271         signal(SIGPIPE, SIG_IGN);
1272         signal(SIGINT, d_flag ? cleanup_handler : SIG_IGN);
1273         signal(SIGHUP, cleanup_handler);
1274         signal(SIGTERM, cleanup_handler);
1275         nalloc = 0;
1276
1277         while (1) {
1278                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1279                 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1280                 saved_errno = errno;
1281                 if (parent_alive_interval != 0)
1282                         check_parent_exists();
1283                 (void) reaper();        /* remove expired keys */
1284                 if (result < 0) {
1285                         if (saved_errno == EINTR)
1286                                 continue;
1287                         fatal("select: %s", strerror(saved_errno));
1288                 } else if (result > 0)
1289                         after_select(readsetp, writesetp);
1290         }
1291         /* NOTREACHED */
1292 }