crypto/openssh/ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.190 2014/07/25 21:22:03 dtucker 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 #ifdef WITH_OPENSSL
  53 #include <openssl/evp.h>
  54 #include "openbsd-compat/openssl-compat.h"
  55 #endif
  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 /* pid of process for which cleanup_socket is applicable */
 130 pid_t cleanup_pid = 0;
 131
 132 /* pathname and directory for AUTH_SOCKET */
 133 char socket_name[MAXPATHLEN];
 134 char socket_dir[MAXPATHLEN];
 135
 136 /* locking */
 137 int locked = 0;
 138 char *lock_passwd = NULL;
 139
 140 extern char *__progname;
 141
 142 /* Default lifetime in seconds (0 == forever) */
 143 static long lifetime = 0;
 144
 145 static void
 146 close_socket(SocketEntry *e)
 147 {
 148         close(e->fd);
 149         e->fd = -1;
 150         e->type = AUTH_UNUSED;
 151         buffer_free(&e->input);
 152         buffer_free(&e->output);
 153         buffer_free(&e->request);
 154 }
 155
 156 static void
 157 idtab_init(void)
 158 {
 159         int i;
 160
 161         for (i = 0; i <=2; i++) {
 162                 TAILQ_INIT(&idtable[i].idlist);
 163                 idtable[i].nentries = 0;
 164         }
 165 }
 166
 167 /* return private key table for requested protocol version */
 168 static Idtab *
 169 idtab_lookup(int version)
 170 {
 171         if (version < 1 || version > 2)
 172                 fatal("internal error, bad protocol version %d", version);
 173         return &idtable[version];
 174 }
 175
 176 static void
 177 free_identity(Identity *id)
 178 {
 179         key_free(id->key);
 180         free(id->provider);
 181         free(id->comment);
 182         free(id);
 183 }
 184
 185 /* return matching private key for given public key */
 186 static Identity *
 187 lookup_identity(Key *key, int version)
 188 {
 189         Identity *id;
 190
 191         Idtab *tab = idtab_lookup(version);
 192         TAILQ_FOREACH(id, &tab->idlist, next) {
 193                 if (key_equal(key, id->key))
 194                         return (id);
 195         }
 196         return (NULL);
 197 }
 198
 199 /* Check confirmation of keysign request */
 200 static int
 201 confirm_key(Identity *id)
 202 {
 203         char *p;
 204         int ret = -1;
 205
 206         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 207         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 208             id->comment, p))
 209                 ret = 0;
 210         free(p);
 211
 212         return (ret);
 213 }
 214
 215 /* send list of supported public keys to 'client' */
 216 static void
 217 process_request_identities(SocketEntry *e, int version)
 218 {
 219         Idtab *tab = idtab_lookup(version);
 220         Identity *id;
 221         Buffer msg;
 222
 223         buffer_init(&msg);
 224         buffer_put_char(&msg, (version == 1) ?
 225             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 226         buffer_put_int(&msg, tab->nentries);
 227         TAILQ_FOREACH(id, &tab->idlist, next) {
 228                 if (id->key->type == KEY_RSA1) {
 229 #ifdef WITH_SSH1
 230                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 231                         buffer_put_bignum(&msg, id->key->rsa->e);
 232                         buffer_put_bignum(&msg, id->key->rsa->n);
 233 #endif
 234                 } else {
 235                         u_char *blob;
 236                         u_int blen;
 237                         key_to_blob(id->key, &blob, &blen);
 238                         buffer_put_string(&msg, blob, blen);
 239                         free(blob);
 240                 }
 241                 buffer_put_cstring(&msg, id->comment);
 242         }
 243         buffer_put_int(&e->output, buffer_len(&msg));
 244         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 245         buffer_free(&msg);
 246 }
 247
 248 #ifdef WITH_SSH1
 249 /* ssh1 only */
 250 static void
 251 process_authentication_challenge1(SocketEntry *e)
 252 {
 253         u_char buf[32], mdbuf[16], session_id[16];
 254         u_int response_type;
 255         BIGNUM *challenge;
 256         Identity *id;
 257         int i, len;
 258         Buffer msg;
 259         struct ssh_digest_ctx *md;
 260         Key *key;
 261
 262         buffer_init(&msg);
 263         key = key_new(KEY_RSA1);
 264         if ((challenge = BN_new()) == NULL)
 265                 fatal("process_authentication_challenge1: BN_new failed");
 266
 267         (void) buffer_get_int(&e->request);                     /* ignored */
 268         buffer_get_bignum(&e->request, key->rsa->e);
 269         buffer_get_bignum(&e->request, key->rsa->n);
 270         buffer_get_bignum(&e->request, challenge);
 271
 272         /* Only protocol 1.1 is supported */
 273         if (buffer_len(&e->request) == 0)
 274                 goto failure;
 275         buffer_get(&e->request, session_id, 16);
 276         response_type = buffer_get_int(&e->request);
 277         if (response_type != 1)
 278                 goto failure;
 279
 280         id = lookup_identity(key, 1);
 281         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 282                 Key *private = id->key;
 283                 /* Decrypt the challenge using the private key. */
 284                 if (rsa_private_decrypt(challenge, challenge, private->rsa) != 0)
 285                         goto failure;
 286
 287                 /* The response is MD5 of decrypted challenge plus session id. */
 288                 len = BN_num_bytes(challenge);
 289                 if (len <= 0 || len > 32) {
 290                         logit("process_authentication_challenge: bad challenge length %d", len);
 291                         goto failure;
 292                 }
 293                 memset(buf, 0, 32);
 294                 BN_bn2bin(challenge, buf + 32 - len);
 295                 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL ||
 296                     ssh_digest_update(md, buf, 32) < 0 ||
 297                     ssh_digest_update(md, session_id, 16) < 0 ||
 298                     ssh_digest_final(md, mdbuf, sizeof(mdbuf)) < 0)
 299                         fatal("%s: md5 failed", __func__);
 300                 ssh_digest_free(md);
 301
 302                 /* Send the response. */
 303                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 304                 for (i = 0; i < 16; i++)
 305                         buffer_put_char(&msg, mdbuf[i]);
 306                 goto send;
 307         }
 308
 309 failure:
 310         /* Unknown identity or protocol error.  Send failure. */
 311         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 312 send:
 313         buffer_put_int(&e->output, buffer_len(&msg));
 314         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 315         key_free(key);
 316         BN_clear_free(challenge);
 317         buffer_free(&msg);
 318 }
 319 #endif
 320
 321 /* ssh2 only */
 322 static void
 323 process_sign_request2(SocketEntry *e)
 324 {
 325         u_char *blob, *data, *signature = NULL;
 326         u_int blen, dlen, slen = 0;
 327         extern int datafellows;
 328         int odatafellows;
 329         int ok = -1, flags;
 330         Buffer msg;
 331         Key *key;
 332
 333         datafellows = 0;
 334
 335         blob = buffer_get_string(&e->request, &blen);
 336         data = buffer_get_string(&e->request, &dlen);
 337
 338         flags = buffer_get_int(&e->request);
 339         odatafellows = datafellows;
 340         if (flags & SSH_AGENT_OLD_SIGNATURE)
 341                 datafellows = SSH_BUG_SIGBLOB;
 342
 343         key = key_from_blob(blob, blen);
 344         if (key != NULL) {
 345                 Identity *id = lookup_identity(key, 2);
 346                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 347                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 348                 key_free(key);
 349         }
 350         buffer_init(&msg);
 351         if (ok == 0) {
 352                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 353                 buffer_put_string(&msg, signature, slen);
 354         } else {
 355                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 356         }
 357         buffer_put_int(&e->output, buffer_len(&msg));
 358         buffer_append(&e->output, buffer_ptr(&msg),
 359             buffer_len(&msg));
 360         buffer_free(&msg);
 361         free(data);
 362         free(blob);
 363         free(signature);
 364         datafellows = odatafellows;
 365 }
 366
 367 /* shared */
 368 static void
 369 process_remove_identity(SocketEntry *e, int version)
 370 {
 371         u_int blen;
 372         int success = 0;
 373         Key *key = NULL;
 374         u_char *blob;
 375 #ifdef WITH_SSH1
 376         u_int bits;
 377 #endif /* WITH_SSH1 */
 378
 379         switch (version) {
 380 #ifdef WITH_SSH1
 381         case 1:
 382                 key = key_new(KEY_RSA1);
 383                 bits = buffer_get_int(&e->request);
 384                 buffer_get_bignum(&e->request, key->rsa->e);
 385                 buffer_get_bignum(&e->request, key->rsa->n);
 386
 387                 if (bits != key_size(key))
 388                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 389                             key_size(key), bits);
 390                 break;
 391 #endif /* WITH_SSH1 */
 392         case 2:
 393                 blob = buffer_get_string(&e->request, &blen);
 394                 key = key_from_blob(blob, blen);
 395                 free(blob);
 396                 break;
 397         }
 398         if (key != NULL) {
 399                 Identity *id = lookup_identity(key, version);
 400                 if (id != NULL) {
 401                         /*
 402                          * We have this key.  Free the old key.  Since we
 403                          * don't want to leave empty slots in the middle of
 404                          * the array, we actually free the key there and move
 405                          * all the entries between the empty slot and the end
 406                          * of the array.
 407                          */
 408                         Idtab *tab = idtab_lookup(version);
 409                         if (tab->nentries < 1)
 410                                 fatal("process_remove_identity: "
 411                                     "internal error: tab->nentries %d",
 412                                     tab->nentries);
 413                         TAILQ_REMOVE(&tab->idlist, id, next);
 414                         free_identity(id);
 415                         tab->nentries--;
 416                         success = 1;
 417                 }
 418                 key_free(key);
 419         }
 420         buffer_put_int(&e->output, 1);
 421         buffer_put_char(&e->output,
 422             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 423 }
 424
 425 static void
 426 process_remove_all_identities(SocketEntry *e, int version)
 427 {
 428         Idtab *tab = idtab_lookup(version);
 429         Identity *id;
 430
 431         /* Loop over all identities and clear the keys. */
 432         for (id = TAILQ_FIRST(&tab->idlist); id;
 433             id = TAILQ_FIRST(&tab->idlist)) {
 434                 TAILQ_REMOVE(&tab->idlist, id, next);
 435                 free_identity(id);
 436         }
 437
 438         /* Mark that there are no identities. */
 439         tab->nentries = 0;
 440
 441         /* Send success. */
 442         buffer_put_int(&e->output, 1);
 443         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 444 }
 445
 446 /* removes expired keys and returns number of seconds until the next expiry */
 447 static time_t
 448 reaper(void)
 449 {
 450         time_t deadline = 0, now = monotime();
 451         Identity *id, *nxt;
 452         int version;
 453         Idtab *tab;
 454
 455         for (version = 1; version < 3; version++) {
 456                 tab = idtab_lookup(version);
 457                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 458                         nxt = TAILQ_NEXT(id, next);
 459                         if (id->death == 0)
 460                                 continue;
 461                         if (now >= id->death) {
 462                                 debug("expiring key '%s'", id->comment);
 463                                 TAILQ_REMOVE(&tab->idlist, id, next);
 464                                 free_identity(id);
 465                                 tab->nentries--;
 466                         } else
 467                                 deadline = (deadline == 0) ? id->death :
 468                                     MIN(deadline, id->death);
 469                 }
 470         }
 471         if (deadline == 0 || deadline <= now)
 472                 return 0;
 473         else
 474                 return (deadline - now);
 475 }
 476
 477 static void
 478 process_add_identity(SocketEntry *e, int version)
 479 {
 480         Idtab *tab = idtab_lookup(version);
 481         Identity *id;
 482         int type, success = 0, confirm = 0;
 483         char *comment;
 484         time_t death = 0;
 485         Key *k = NULL;
 486
 487         switch (version) {
 488 #ifdef WITH_SSH1
 489         case 1:
 490                 k = key_new_private(KEY_RSA1);
 491                 (void) buffer_get_int(&e->request);             /* ignored */
 492                 buffer_get_bignum(&e->request, k->rsa->n);
 493                 buffer_get_bignum(&e->request, k->rsa->e);
 494                 buffer_get_bignum(&e->request, k->rsa->d);
 495                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 496
 497                 /* SSH and SSL have p and q swapped */
 498                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 499                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 500
 501                 /* Generate additional parameters */
 502                 if (rsa_generate_additional_parameters(k->rsa) != 0)
 503                         fatal("%s: rsa_generate_additional_parameters "
 504                             "error", __func__);
 505
 506                 /* enable blinding */
 507                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 508                         error("process_add_identity: RSA_blinding_on failed");
 509                         key_free(k);
 510                         goto send;
 511                 }
 512                 break;
 513 #endif /* WITH_SSH1 */
 514         case 2:
 515                 k = key_private_deserialize(&e->request);
 516                 if (k == NULL) {
 517                         buffer_clear(&e->request);
 518                         goto send;
 519                 }
 520                 break;
 521         }
 522         if (k == NULL)
 523                 goto send;
 524         comment = buffer_get_string(&e->request, NULL);
 525
 526         while (buffer_len(&e->request)) {
 527                 switch ((type = buffer_get_char(&e->request))) {
 528                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 529                         death = monotime() + buffer_get_int(&e->request);
 530                         break;
 531                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 532                         confirm = 1;
 533                         break;
 534                 default:
 535                         error("process_add_identity: "
 536                             "Unknown constraint type %d", type);
 537                         free(comment);
 538                         key_free(k);
 539                         goto send;
 540                 }
 541         }
 542         success = 1;
 543         if (lifetime && !death)
 544                 death = monotime() + lifetime;
 545         if ((id = lookup_identity(k, version)) == NULL) {
 546                 id = xcalloc(1, sizeof(Identity));
 547                 id->key = k;
 548                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 549                 /* Increment the number of identities. */
 550                 tab->nentries++;
 551         } else {
 552                 key_free(k);
 553                 free(id->comment);
 554         }
 555         id->comment = comment;
 556         id->death = death;
 557         id->confirm = confirm;
 558 send:
 559         buffer_put_int(&e->output, 1);
 560         buffer_put_char(&e->output,
 561             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 562 }
 563
 564 /* XXX todo: encrypt sensitive data with passphrase */
 565 static void
 566 process_lock_agent(SocketEntry *e, int lock)
 567 {
 568         int success = 0;
 569         char *passwd;
 570
 571         passwd = buffer_get_string(&e->request, NULL);
 572         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 573                 locked = 0;
 574                 explicit_bzero(lock_passwd, strlen(lock_passwd));
 575                 free(lock_passwd);
 576                 lock_passwd = NULL;
 577                 success = 1;
 578         } else if (!locked && lock) {
 579                 locked = 1;
 580                 lock_passwd = xstrdup(passwd);
 581                 success = 1;
 582         }
 583         explicit_bzero(passwd, strlen(passwd));
 584         free(passwd);
 585
 586         buffer_put_int(&e->output, 1);
 587         buffer_put_char(&e->output,
 588             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 589 }
 590
 591 static void
 592 no_identities(SocketEntry *e, u_int type)
 593 {
 594         Buffer msg;
 595
 596         buffer_init(&msg);
 597         buffer_put_char(&msg,
 598             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 599             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 600         buffer_put_int(&msg, 0);
 601         buffer_put_int(&e->output, buffer_len(&msg));
 602         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 603         buffer_free(&msg);
 604 }
 605
 606 #ifdef ENABLE_PKCS11
 607 static void
 608 process_add_smartcard_key(SocketEntry *e)
 609 {
 610         char *provider = NULL, *pin;
 611         int i, type, version, count = 0, success = 0, confirm = 0;
 612         time_t death = 0;
 613         Key **keys = NULL, *k;
 614         Identity *id;
 615         Idtab *tab;
 616
 617         provider = buffer_get_string(&e->request, NULL);
 618         pin = buffer_get_string(&e->request, NULL);
 619
 620         while (buffer_len(&e->request)) {
 621                 switch ((type = buffer_get_char(&e->request))) {
 622                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 623                         death = monotime() + buffer_get_int(&e->request);
 624                         break;
 625                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 626                         confirm = 1;
 627                         break;
 628                 default:
 629                         error("process_add_smartcard_key: "
 630                             "Unknown constraint type %d", type);
 631                         goto send;
 632                 }
 633         }
 634         if (lifetime && !death)
 635                 death = monotime() + lifetime;
 636
 637         count = pkcs11_add_provider(provider, pin, &keys);
 638         for (i = 0; i < count; i++) {
 639                 k = keys[i];
 640                 version = k->type == KEY_RSA1 ? 1 : 2;
 641                 tab = idtab_lookup(version);
 642                 if (lookup_identity(k, version) == NULL) {
 643                         id = xcalloc(1, sizeof(Identity));
 644                         id->key = k;
 645                         id->provider = xstrdup(provider);
 646                         id->comment = xstrdup(provider); /* XXX */
 647                         id->death = death;
 648                         id->confirm = confirm;
 649                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 650                         tab->nentries++;
 651                         success = 1;
 652                 } else {
 653                         key_free(k);
 654                 }
 655                 keys[i] = NULL;
 656         }
 657 send:
 658         free(pin);
 659         free(provider);
 660         free(keys);
 661         buffer_put_int(&e->output, 1);
 662         buffer_put_char(&e->output,
 663             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 664 }
 665
 666 static void
 667 process_remove_smartcard_key(SocketEntry *e)
 668 {
 669         char *provider = NULL, *pin = NULL;
 670         int version, success = 0;
 671         Identity *id, *nxt;
 672         Idtab *tab;
 673
 674         provider = buffer_get_string(&e->request, NULL);
 675         pin = buffer_get_string(&e->request, NULL);
 676         free(pin);
 677
 678         for (version = 1; version < 3; version++) {
 679                 tab = idtab_lookup(version);
 680                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 681                         nxt = TAILQ_NEXT(id, next);
 682                         /* Skip file--based keys */
 683                         if (id->provider == NULL)
 684                                 continue;
 685                         if (!strcmp(provider, id->provider)) {
 686                                 TAILQ_REMOVE(&tab->idlist, id, next);
 687                                 free_identity(id);
 688                                 tab->nentries--;
 689                         }
 690                 }
 691         }
 692         if (pkcs11_del_provider(provider) == 0)
 693                 success = 1;
 694         else
 695                 error("process_remove_smartcard_key:"
 696                     " pkcs11_del_provider failed");
 697         free(provider);
 698         buffer_put_int(&e->output, 1);
 699         buffer_put_char(&e->output,
 700             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 701 }
 702 #endif /* ENABLE_PKCS11 */
 703
 704 /* dispatch incoming messages */
 705
 706 static void
 707 process_message(SocketEntry *e)
 708 {
 709         u_int msg_len, type;
 710         u_char *cp;
 711
 712         if (buffer_len(&e->input) < 5)
 713                 return;         /* Incomplete message. */
 714         cp = buffer_ptr(&e->input);
 715         msg_len = get_u32(cp);
 716         if (msg_len > 256 * 1024) {
 717                 close_socket(e);
 718                 return;
 719         }
 720         if (buffer_len(&e->input) < msg_len + 4)
 721                 return;
 722
 723         /* move the current input to e->request */
 724         buffer_consume(&e->input, 4);
 725         buffer_clear(&e->request);
 726         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 727         buffer_consume(&e->input, msg_len);
 728         type = buffer_get_char(&e->request);
 729
 730         /* check wheter agent is locked */
 731         if (locked && type != SSH_AGENTC_UNLOCK) {
 732                 buffer_clear(&e->request);
 733                 switch (type) {
 734                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 735                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 736                         /* send empty lists */
 737                         no_identities(e, type);
 738                         break;
 739                 default:
 740                         /* send a fail message for all other request types */
 741                         buffer_put_int(&e->output, 1);
 742                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 743                 }
 744                 return;
 745         }
 746
 747         debug("type %d", type);
 748         switch (type) {
 749         case SSH_AGENTC_LOCK:
 750         case SSH_AGENTC_UNLOCK:
 751                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 752                 break;
 753 #ifdef WITH_SSH1
 754         /* ssh1 */
 755         case SSH_AGENTC_RSA_CHALLENGE:
 756                 process_authentication_challenge1(e);
 757                 break;
 758         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 759                 process_request_identities(e, 1);
 760                 break;
 761         case SSH_AGENTC_ADD_RSA_IDENTITY:
 762         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 763                 process_add_identity(e, 1);
 764                 break;
 765         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 766                 process_remove_identity(e, 1);
 767                 break;
 768         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 769                 process_remove_all_identities(e, 1);
 770                 break;
 771 #endif
 772         /* ssh2 */
 773         case SSH2_AGENTC_SIGN_REQUEST:
 774                 process_sign_request2(e);
 775                 break;
 776         case SSH2_AGENTC_REQUEST_IDENTITIES:
 777                 process_request_identities(e, 2);
 778                 break;
 779         case SSH2_AGENTC_ADD_IDENTITY:
 780         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 781                 process_add_identity(e, 2);
 782                 break;
 783         case SSH2_AGENTC_REMOVE_IDENTITY:
 784                 process_remove_identity(e, 2);
 785                 break;
 786         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 787                 process_remove_all_identities(e, 2);
 788                 break;
 789 #ifdef ENABLE_PKCS11
 790         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 791         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 792                 process_add_smartcard_key(e);
 793                 break;
 794         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 795                 process_remove_smartcard_key(e);
 796                 break;
 797 #endif /* ENABLE_PKCS11 */
 798         default:
 799                 /* Unknown message.  Respond with failure. */
 800                 error("Unknown message %d", type);
 801                 buffer_clear(&e->request);
 802                 buffer_put_int(&e->output, 1);
 803                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 804                 break;
 805         }
 806 }
 807
 808 static void
 809 new_socket(sock_type type, int fd)
 810 {
 811         u_int i, old_alloc, new_alloc;
 812
 813         set_nonblock(fd);
 814
 815         if (fd > max_fd)
 816                 max_fd = fd;
 817
 818         for (i = 0; i < sockets_alloc; i++)
 819                 if (sockets[i].type == AUTH_UNUSED) {
 820                         sockets[i].fd = fd;
 821                         buffer_init(&sockets[i].input);
 822                         buffer_init(&sockets[i].output);
 823                         buffer_init(&sockets[i].request);
 824                         sockets[i].type = type;
 825                         return;
 826                 }
 827         old_alloc = sockets_alloc;
 828         new_alloc = sockets_alloc + 10;
 829         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 830         for (i = old_alloc; i < new_alloc; i++)
 831                 sockets[i].type = AUTH_UNUSED;
 832         sockets_alloc = new_alloc;
 833         sockets[old_alloc].fd = fd;
 834         buffer_init(&sockets[old_alloc].input);
 835         buffer_init(&sockets[old_alloc].output);
 836         buffer_init(&sockets[old_alloc].request);
 837         sockets[old_alloc].type = type;
 838 }
 839
 840 static int
 841 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
 842     struct timeval **tvpp)
 843 {
 844         u_int i, sz;
 845         int n = 0;
 846         static struct timeval tv;
 847         time_t deadline;
 848
 849         for (i = 0; i < sockets_alloc; i++) {
 850                 switch (sockets[i].type) {
 851                 case AUTH_SOCKET:
 852                 case AUTH_CONNECTION:
 853                         n = MAX(n, sockets[i].fd);
 854                         break;
 855                 case AUTH_UNUSED:
 856                         break;
 857                 default:
 858                         fatal("Unknown socket type %d", sockets[i].type);
 859                         break;
 860                 }
 861         }
 862
 863         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 864         if (*fdrp == NULL || sz > *nallocp) {
 865                 free(*fdrp);
 866                 free(*fdwp);
 867                 *fdrp = xmalloc(sz);
 868                 *fdwp = xmalloc(sz);
 869                 *nallocp = sz;
 870         }
 871         if (n < *fdl)
 872                 debug("XXX shrink: %d < %d", n, *fdl);
 873         *fdl = n;
 874         memset(*fdrp, 0, sz);
 875         memset(*fdwp, 0, sz);
 876
 877         for (i = 0; i < sockets_alloc; i++) {
 878                 switch (sockets[i].type) {
 879                 case AUTH_SOCKET:
 880                 case AUTH_CONNECTION:
 881                         FD_SET(sockets[i].fd, *fdrp);
 882                         if (buffer_len(&sockets[i].output) > 0)
 883                                 FD_SET(sockets[i].fd, *fdwp);
 884                         break;
 885                 default:
 886                         break;
 887                 }
 888         }
 889         deadline = reaper();
 890         if (parent_alive_interval != 0)
 891                 deadline = (deadline == 0) ? parent_alive_interval :
 892                     MIN(deadline, parent_alive_interval);
 893         if (deadline == 0) {
 894                 *tvpp = NULL;
 895         } else {
 896                 tv.tv_sec = deadline;
 897                 tv.tv_usec = 0;
 898                 *tvpp = &tv;
 899         }
 900         return (1);
 901 }
 902
 903 static void
 904 after_select(fd_set *readset, fd_set *writeset)
 905 {
 906         struct sockaddr_un sunaddr;
 907         socklen_t slen;
 908         char buf[1024];
 909         int len, sock;
 910         u_int i, orig_alloc;
 911         uid_t euid;
 912         gid_t egid;
 913
 914         for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++)
 915                 switch (sockets[i].type) {
 916                 case AUTH_UNUSED:
 917                         break;
 918                 case AUTH_SOCKET:
 919                         if (FD_ISSET(sockets[i].fd, readset)) {
 920                                 slen = sizeof(sunaddr);
 921                                 sock = accept(sockets[i].fd,
 922                                     (struct sockaddr *)&sunaddr, &slen);
 923                                 if (sock < 0) {
 924                                         error("accept from AUTH_SOCKET: %s",
 925                                             strerror(errno));
 926                                         break;
 927                                 }
 928                                 if (getpeereid(sock, &euid, &egid) < 0) {
 929                                         error("getpeereid %d failed: %s",
 930                                             sock, strerror(errno));
 931                                         close(sock);
 932                                         break;
 933                                 }
 934                                 if ((euid != 0) && (getuid() != euid)) {
 935                                         error("uid mismatch: "
 936                                             "peer euid %u != uid %u",
 937                                             (u_int) euid, (u_int) getuid());
 938                                         close(sock);
 939                                         break;
 940                                 }
 941                                 new_socket(AUTH_CONNECTION, sock);
 942                         }
 943                         break;
 944                 case AUTH_CONNECTION:
 945                         if (buffer_len(&sockets[i].output) > 0 &&
 946                             FD_ISSET(sockets[i].fd, writeset)) {
 947                                 len = write(sockets[i].fd,
 948                                     buffer_ptr(&sockets[i].output),
 949                                     buffer_len(&sockets[i].output));
 950                                 if (len == -1 && (errno == EAGAIN ||
 951                                     errno == EWOULDBLOCK ||
 952                                     errno == EINTR))
 953                                         continue;
 954                                 if (len <= 0) {
 955                                         close_socket(&sockets[i]);
 956                                         break;
 957                                 }
 958                                 buffer_consume(&sockets[i].output, len);
 959                         }
 960                         if (FD_ISSET(sockets[i].fd, readset)) {
 961                                 len = read(sockets[i].fd, buf, sizeof(buf));
 962                                 if (len == -1 && (errno == EAGAIN ||
 963                                     errno == EWOULDBLOCK ||
 964                                     errno == EINTR))
 965                                         continue;
 966                                 if (len <= 0) {
 967                                         close_socket(&sockets[i]);
 968                                         break;
 969                                 }
 970                                 buffer_append(&sockets[i].input, buf, len);
 971                                 explicit_bzero(buf, sizeof(buf));
 972                                 process_message(&sockets[i]);
 973                         }
 974                         break;
 975                 default:
 976                         fatal("Unknown type %d", sockets[i].type);
 977                 }
 978 }
 979
 980 static void
 981 cleanup_socket(void)
 982 {
 983         if (cleanup_pid != 0 && getpid() != cleanup_pid)
 984                 return;
 985         debug("%s: cleanup", __func__);
 986         if (socket_name[0])
 987                 unlink(socket_name);
 988         if (socket_dir[0])
 989                 rmdir(socket_dir);
 990 }
 991
 992 void
 993 cleanup_exit(int i)
 994 {
 995         cleanup_socket();
 996         _exit(i);
 997 }
 998
 999 /*ARGSUSED*/
1000 static void
1001 cleanup_handler(int sig)
1002 {
1003         cleanup_socket();
1004 #ifdef ENABLE_PKCS11
1005         pkcs11_terminate();
1006 #endif
1007         _exit(2);
1008 }
1009
1010 static void
1011 check_parent_exists(void)
1012 {
1013         /*
1014          * If our parent has exited then getppid() will return (pid_t)1,
1015          * so testing for that should be safe.
1016          */
1017         if (parent_pid != -1 && getppid() != parent_pid) {
1018                 /* printf("Parent has died - Authentication agent exiting.\n"); */
1019                 cleanup_socket();
1020                 _exit(2);
1021         }
1022 }
1023
1024 static void
1025 usage(void)
1026 {
1027         fprintf(stderr,
1028             "usage: ssh-agent [-c | -s] [-d] [-a bind_address] [-t life]\n"
1029             "                 [command [arg ...]]\n"
1030             "       ssh-agent [-c | -s] -k\n");
1031         exit(1);
1032 }
1033
1034 int
1035 main(int ac, char **av)
1036 {
1037         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1038         int sock, fd, ch, result, saved_errno;
1039         u_int nalloc;
1040         char *shell, *format, *pidstr, *agentsocket = NULL;
1041         fd_set *readsetp = NULL, *writesetp = NULL;
1042 #ifdef HAVE_SETRLIMIT
1043         struct rlimit rlim;
1044 #endif
1045         extern int optind;
1046         extern char *optarg;
1047         pid_t pid;
1048         char pidstrbuf[1 + 3 * sizeof pid];
1049         struct timeval *tvp = NULL;
1050         size_t len;
1051         mode_t prev_mask;
1052
1053         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1054         sanitise_stdfd();
1055
1056         /* drop */
1057         setegid(getgid());
1058         setgid(getgid());
1059
1060 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1061         /* Disable ptrace on Linux without sgid bit */
1062         prctl(PR_SET_DUMPABLE, 0);
1063 #endif
1064
1065 #ifdef WITH_OPENSSL
1066         OpenSSL_add_all_algorithms();
1067 #endif
1068
1069         __progname = ssh_get_progname(av[0]);
1070         seed_rng();
1071
1072         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1073                 switch (ch) {
1074                 case 'c':
1075                         if (s_flag)
1076                                 usage();
1077                         c_flag++;
1078                         break;
1079                 case 'k':
1080                         k_flag++;
1081                         break;
1082                 case 's':
1083                         if (c_flag)
1084                                 usage();
1085                         s_flag++;
1086                         break;
1087                 case 'd':
1088                         if (d_flag)
1089                                 usage();
1090                         d_flag++;
1091                         break;
1092                 case 'a':
1093                         agentsocket = optarg;
1094                         break;
1095                 case 't':
1096                         if ((lifetime = convtime(optarg)) == -1) {
1097                                 fprintf(stderr, "Invalid lifetime\n");
1098                                 usage();
1099                         }
1100                         break;
1101                 default:
1102                         usage();
1103                 }
1104         }
1105         ac -= optind;
1106         av += optind;
1107
1108         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1109                 usage();
1110
1111         if (ac == 0 && !c_flag && !s_flag) {
1112                 shell = getenv("SHELL");
1113                 if (shell != NULL && (len = strlen(shell)) > 2 &&
1114                     strncmp(shell + len - 3, "csh", 3) == 0)
1115                         c_flag = 1;
1116         }
1117         if (k_flag) {
1118                 const char *errstr = NULL;
1119
1120                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1121                 if (pidstr == NULL) {
1122                         fprintf(stderr, "%s not set, cannot kill agent\n",
1123                             SSH_AGENTPID_ENV_NAME);
1124                         exit(1);
1125                 }
1126                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1127                 if (errstr) {
1128                         fprintf(stderr,
1129                             "%s=\"%s\", which is not a good PID: %s\n",
1130                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1131                         exit(1);
1132                 }
1133                 if (kill(pid, SIGTERM) == -1) {
1134                         perror("kill");
1135                         exit(1);
1136                 }
1137                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1138                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1139                 printf(format, SSH_AGENTPID_ENV_NAME);
1140                 printf("echo Agent pid %ld killed;\n", (long)pid);
1141                 exit(0);
1142         }
1143         parent_pid = getpid();
1144
1145         if (agentsocket == NULL) {
1146                 /* Create private directory for agent socket */
1147                 mktemp_proto(socket_dir, sizeof(socket_dir));
1148                 if (mkdtemp(socket_dir) == NULL) {
1149                         perror("mkdtemp: private socket dir");
1150                         exit(1);
1151                 }
1152                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1153                     (long)parent_pid);
1154         } else {
1155                 /* Try to use specified agent socket */
1156                 socket_dir[0] = '\0';
1157                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1158         }
1159
1160         /*
1161          * Create socket early so it will exist before command gets run from
1162          * the parent.
1163          */
1164         prev_mask = umask(0177);
1165         sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0);
1166         if (sock < 0) {
1167                 /* XXX - unix_listener() calls error() not perror() */
1168                 *socket_name = '\0'; /* Don't unlink any existing file */
1169                 cleanup_exit(1);
1170         }
1171         umask(prev_mask);
1172
1173         /*
1174          * Fork, and have the parent execute the command, if any, or present
1175          * the socket data.  The child continues as the authentication agent.
1176          */
1177         if (d_flag) {
1178                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1179                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1180                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1181                     SSH_AUTHSOCKET_ENV_NAME);
1182                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1183                 goto skip;
1184         }
1185         pid = fork();
1186         if (pid == -1) {
1187                 perror("fork");
1188                 cleanup_exit(1);
1189         }
1190         if (pid != 0) {         /* Parent - execute the given command. */
1191                 close(sock);
1192                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1193                 if (ac == 0) {
1194                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1195                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1196                             SSH_AUTHSOCKET_ENV_NAME);
1197                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1198                             SSH_AGENTPID_ENV_NAME);
1199                         printf("echo Agent pid %ld;\n", (long)pid);
1200                         exit(0);
1201                 }
1202                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1203                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1204                         perror("setenv");
1205                         exit(1);
1206                 }
1207                 execvp(av[0], av);
1208                 perror(av[0]);
1209                 exit(1);
1210         }
1211         /* child */
1212         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1213
1214         if (setsid() == -1) {
1215                 error("setsid: %s", strerror(errno));
1216                 cleanup_exit(1);
1217         }
1218
1219         (void)chdir("/");
1220         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1221                 /* XXX might close listen socket */
1222                 (void)dup2(fd, STDIN_FILENO);
1223                 (void)dup2(fd, STDOUT_FILENO);
1224                 (void)dup2(fd, STDERR_FILENO);
1225                 if (fd > 2)
1226                         close(fd);
1227         }
1228
1229 #ifdef HAVE_SETRLIMIT
1230         /* deny core dumps, since memory contains unencrypted private keys */
1231         rlim.rlim_cur = rlim.rlim_max = 0;
1232         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1233                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1234                 cleanup_exit(1);
1235         }
1236 #endif
1237
1238 skip:
1239
1240         cleanup_pid = getpid();
1241
1242 #ifdef ENABLE_PKCS11
1243         pkcs11_init(0);
1244 #endif
1245         new_socket(AUTH_SOCKET, sock);
1246         if (ac > 0)
1247                 parent_alive_interval = 10;
1248         idtab_init();
1249         signal(SIGPIPE, SIG_IGN);
1250         signal(SIGINT, d_flag ? cleanup_handler : SIG_IGN);
1251         signal(SIGHUP, cleanup_handler);
1252         signal(SIGTERM, cleanup_handler);
1253         nalloc = 0;
1254
1255         while (1) {
1256                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1257                 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1258                 saved_errno = errno;
1259                 if (parent_alive_interval != 0)
1260                         check_parent_exists();
1261                 (void) reaper();        /* remove expired keys */
1262                 if (result < 0) {
1263                         if (saved_errno == EINTR)
1264                                 continue;
1265                         fatal("select: %s", strerror(saved_errno));
1266                 } else if (result > 0)
1267                         after_select(readsetp, writesetp);
1268         }
1269         /* NOTREACHED */
1270 }