crypto/openssh/ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.183 2014/02/02 03:44:31 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * The authentication agent program.
   7  *
   8  * As far as I am concerned, the code I have written for this software
   9  * can be used freely for any purpose.  Any derived versions of this
  10  * software must be clearly marked as such, and if the derived work is
  11  * incompatible with the protocol description in the RFC file, it must be
  12  * called by a name other than "ssh" or "Secure Shell".
  13  *
  14  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  15  *
  16  * Redistribution and use in source and binary forms, with or without
  17  * modification, are permitted provided that the following conditions
  18  * are met:
  19  * 1. Redistributions of source code must retain the above copyright
  20  *    notice, this list of conditions and the following disclaimer.
  21  * 2. Redistributions in binary form must reproduce the above copyright
  22  *    notice, this list of conditions and the following disclaimer in the
  23  *    documentation and/or other materials provided with the distribution.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  26  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  27  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  28  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  29  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  30  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  31  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  32  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  33  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  34  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  35  */
  36
  37 #include "includes.h"
  38 __RCSID("$FreeBSD$");
  39
  40 #include <sys/types.h>
  41 #include <sys/param.h>
  42 #include <sys/resource.h>
  43 #include <sys/stat.h>
  44 #include <sys/socket.h>
  45 #ifdef HAVE_SYS_TIME_H
  46 # include <sys/time.h>
  47 #endif
  48 #ifdef HAVE_SYS_UN_H
  49 # include <sys/un.h>
  50 #endif
  51 #include "openbsd-compat/sys-queue.h"
  52
  53 #include <openssl/evp.h>
  54 #include "openbsd-compat/openssl-compat.h"
  55
  56 #include <errno.h>
  57 #include <fcntl.h>
  58 #ifdef HAVE_PATHS_H
  59 # include <paths.h>
  60 #endif
  61 #include <signal.h>
  62 #include <stdarg.h>
  63 #include <stdio.h>
  64 #include <stdlib.h>
  65 #include <time.h>
  66 #include <string.h>
  67 #include <unistd.h>
  68
  69 #include "xmalloc.h"
  70 #include "ssh.h"
  71 #include "rsa.h"
  72 #include "buffer.h"
  73 #include "key.h"
  74 #include "authfd.h"
  75 #include "compat.h"
  76 #include "log.h"
  77 #include "misc.h"
  78 #include "digest.h"
  79
  80 #ifdef ENABLE_PKCS11
  81 #include "ssh-pkcs11.h"
  82 #endif
  83
  84 #if defined(HAVE_SYS_PRCTL_H)
  85 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  86 #endif
  87
  88 typedef enum {
  89         AUTH_UNUSED,
  90         AUTH_SOCKET,
  91         AUTH_CONNECTION
  92 } sock_type;
  93
  94 typedef struct {
  95         int fd;
  96         sock_type type;
  97         Buffer input;
  98         Buffer output;
  99         Buffer request;
 100 } SocketEntry;
 101
 102 u_int sockets_alloc = 0;
 103 SocketEntry *sockets = NULL;
 104
 105 typedef struct identity {
 106         TAILQ_ENTRY(identity) next;
 107         Key *key;
 108         char *comment;
 109         char *provider;
 110         time_t death;
 111         u_int confirm;
 112 } Identity;
 113
 114 typedef struct {
 115         int nentries;
 116         TAILQ_HEAD(idqueue, identity) idlist;
 117 } Idtab;
 118
 119 /* private key table, one per protocol version */
 120 Idtab idtable[3];
 121
 122 int max_fd = 0;
 123
 124 /* pid of shell == parent of agent */
 125 pid_t parent_pid = -1;
 126 time_t parent_alive_interval = 0;
 127
 128 /* pathname and directory for AUTH_SOCKET */
 129 char socket_name[MAXPATHLEN];
 130 char socket_dir[MAXPATHLEN];
 131
 132 /* locking */
 133 int locked = 0;
 134 char *lock_passwd = NULL;
 135
 136 extern char *__progname;
 137
 138 /* Default lifetime in seconds (0 == forever) */
 139 static long lifetime = 0;
 140
 141 /*
 142  * Client connection count; incremented in new_socket() and decremented in
 143  * close_socket().  When it reaches 0, ssh-agent will exit.  Since it is
 144  * normally initialized to 1, it will never reach 0.  However, if the -x
 145  * option is specified, it is initialized to 0 in main(); in that case,
 146  * ssh-agent will exit as soon as it has had at least one client but no
 147  * longer has any.
 148  */
 149 static int xcount = 1;
 150
 151 static void
 152 close_socket(SocketEntry *e)
 153 {
 154         int last = 0;
 155
 156         if (e->type == AUTH_CONNECTION) {
 157                 debug("xcount %d -> %d", xcount, xcount - 1);
 158                 if (--xcount == 0)
 159                         last = 1;
 160         }
 161         close(e->fd);
 162         e->fd = -1;
 163         e->type = AUTH_UNUSED;
 164         buffer_free(&e->input);
 165         buffer_free(&e->output);
 166         buffer_free(&e->request);
 167         if (last)
 168                 cleanup_exit(0);
 169 }
 170
 171 static void
 172 idtab_init(void)
 173 {
 174         int i;
 175
 176         for (i = 0; i <=2; i++) {
 177                 TAILQ_INIT(&idtable[i].idlist);
 178                 idtable[i].nentries = 0;
 179         }
 180 }
 181
 182 /* return private key table for requested protocol version */
 183 static Idtab *
 184 idtab_lookup(int version)
 185 {
 186         if (version < 1 || version > 2)
 187                 fatal("internal error, bad protocol version %d", version);
 188         return &idtable[version];
 189 }
 190
 191 static void
 192 free_identity(Identity *id)
 193 {
 194         key_free(id->key);
 195         free(id->provider);
 196         free(id->comment);
 197         free(id);
 198 }
 199
 200 /* return matching private key for given public key */
 201 static Identity *
 202 lookup_identity(Key *key, int version)
 203 {
 204         Identity *id;
 205
 206         Idtab *tab = idtab_lookup(version);
 207         TAILQ_FOREACH(id, &tab->idlist, next) {
 208                 if (key_equal(key, id->key))
 209                         return (id);
 210         }
 211         return (NULL);
 212 }
 213
 214 /* Check confirmation of keysign request */
 215 static int
 216 confirm_key(Identity *id)
 217 {
 218         char *p;
 219         int ret = -1;
 220
 221         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 222         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 223             id->comment, p))
 224                 ret = 0;
 225         free(p);
 226
 227         return (ret);
 228 }
 229
 230 /* send list of supported public keys to 'client' */
 231 static void
 232 process_request_identities(SocketEntry *e, int version)
 233 {
 234         Idtab *tab = idtab_lookup(version);
 235         Identity *id;
 236         Buffer msg;
 237
 238         buffer_init(&msg);
 239         buffer_put_char(&msg, (version == 1) ?
 240             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 241         buffer_put_int(&msg, tab->nentries);
 242         TAILQ_FOREACH(id, &tab->idlist, next) {
 243                 if (id->key->type == KEY_RSA1) {
 244                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 245                         buffer_put_bignum(&msg, id->key->rsa->e);
 246                         buffer_put_bignum(&msg, id->key->rsa->n);
 247                 } else {
 248                         u_char *blob;
 249                         u_int blen;
 250                         key_to_blob(id->key, &blob, &blen);
 251                         buffer_put_string(&msg, blob, blen);
 252                         free(blob);
 253                 }
 254                 buffer_put_cstring(&msg, id->comment);
 255         }
 256         buffer_put_int(&e->output, buffer_len(&msg));
 257         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 258         buffer_free(&msg);
 259 }
 260
 261 /* ssh1 only */
 262 static void
 263 process_authentication_challenge1(SocketEntry *e)
 264 {
 265         u_char buf[32], mdbuf[16], session_id[16];
 266         u_int response_type;
 267         BIGNUM *challenge;
 268         Identity *id;
 269         int i, len;
 270         Buffer msg;
 271         struct ssh_digest_ctx *md;
 272         Key *key;
 273
 274         buffer_init(&msg);
 275         key = key_new(KEY_RSA1);
 276         if ((challenge = BN_new()) == NULL)
 277                 fatal("process_authentication_challenge1: BN_new failed");
 278
 279         (void) buffer_get_int(&e->request);                     /* ignored */
 280         buffer_get_bignum(&e->request, key->rsa->e);
 281         buffer_get_bignum(&e->request, key->rsa->n);
 282         buffer_get_bignum(&e->request, challenge);
 283
 284         /* Only protocol 1.1 is supported */
 285         if (buffer_len(&e->request) == 0)
 286                 goto failure;
 287         buffer_get(&e->request, session_id, 16);
 288         response_type = buffer_get_int(&e->request);
 289         if (response_type != 1)
 290                 goto failure;
 291
 292         id = lookup_identity(key, 1);
 293         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 294                 Key *private = id->key;
 295                 /* Decrypt the challenge using the private key. */
 296                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 297                         goto failure;
 298
 299                 /* The response is MD5 of decrypted challenge plus session id. */
 300                 len = BN_num_bytes(challenge);
 301                 if (len <= 0 || len > 32) {
 302                         logit("process_authentication_challenge: bad challenge length %d", len);
 303                         goto failure;
 304                 }
 305                 memset(buf, 0, 32);
 306                 BN_bn2bin(challenge, buf + 32 - len);
 307                 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL ||
 308                     ssh_digest_update(md, buf, 32) < 0 ||
 309                     ssh_digest_update(md, session_id, 16) < 0 ||
 310                     ssh_digest_final(md, mdbuf, sizeof(mdbuf)) < 0)
 311                         fatal("%s: md5 failed", __func__);
 312                 ssh_digest_free(md);
 313
 314                 /* Send the response. */
 315                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 316                 for (i = 0; i < 16; i++)
 317                         buffer_put_char(&msg, mdbuf[i]);
 318                 goto send;
 319         }
 320
 321 failure:
 322         /* Unknown identity or protocol error.  Send failure. */
 323         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 324 send:
 325         buffer_put_int(&e->output, buffer_len(&msg));
 326         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 327         key_free(key);
 328         BN_clear_free(challenge);
 329         buffer_free(&msg);
 330 }
 331
 332 /* ssh2 only */
 333 static void
 334 process_sign_request2(SocketEntry *e)
 335 {
 336         u_char *blob, *data, *signature = NULL;
 337         u_int blen, dlen, slen = 0;
 338         extern int datafellows;
 339         int odatafellows;
 340         int ok = -1, flags;
 341         Buffer msg;
 342         Key *key;
 343
 344         datafellows = 0;
 345
 346         blob = buffer_get_string(&e->request, &blen);
 347         data = buffer_get_string(&e->request, &dlen);
 348
 349         flags = buffer_get_int(&e->request);
 350         odatafellows = datafellows;
 351         if (flags & SSH_AGENT_OLD_SIGNATURE)
 352                 datafellows = SSH_BUG_SIGBLOB;
 353
 354         key = key_from_blob(blob, blen);
 355         if (key != NULL) {
 356                 Identity *id = lookup_identity(key, 2);
 357                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 358                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 359                 key_free(key);
 360         }
 361         buffer_init(&msg);
 362         if (ok == 0) {
 363                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 364                 buffer_put_string(&msg, signature, slen);
 365         } else {
 366                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 367         }
 368         buffer_put_int(&e->output, buffer_len(&msg));
 369         buffer_append(&e->output, buffer_ptr(&msg),
 370             buffer_len(&msg));
 371         buffer_free(&msg);
 372         free(data);
 373         free(blob);
 374         free(signature);
 375         datafellows = odatafellows;
 376 }
 377
 378 /* shared */
 379 static void
 380 process_remove_identity(SocketEntry *e, int version)
 381 {
 382         u_int blen, bits;
 383         int success = 0;
 384         Key *key = NULL;
 385         u_char *blob;
 386
 387         switch (version) {
 388         case 1:
 389                 key = key_new(KEY_RSA1);
 390                 bits = buffer_get_int(&e->request);
 391                 buffer_get_bignum(&e->request, key->rsa->e);
 392                 buffer_get_bignum(&e->request, key->rsa->n);
 393
 394                 if (bits != key_size(key))
 395                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 396                             key_size(key), bits);
 397                 break;
 398         case 2:
 399                 blob = buffer_get_string(&e->request, &blen);
 400                 key = key_from_blob(blob, blen);
 401                 free(blob);
 402                 break;
 403         }
 404         if (key != NULL) {
 405                 Identity *id = lookup_identity(key, version);
 406                 if (id != NULL) {
 407                         /*
 408                          * We have this key.  Free the old key.  Since we
 409                          * don't want to leave empty slots in the middle of
 410                          * the array, we actually free the key there and move
 411                          * all the entries between the empty slot and the end
 412                          * of the array.
 413                          */
 414                         Idtab *tab = idtab_lookup(version);
 415                         if (tab->nentries < 1)
 416                                 fatal("process_remove_identity: "
 417                                     "internal error: tab->nentries %d",
 418                                     tab->nentries);
 419                         TAILQ_REMOVE(&tab->idlist, id, next);
 420                         free_identity(id);
 421                         tab->nentries--;
 422                         success = 1;
 423                 }
 424                 key_free(key);
 425         }
 426         buffer_put_int(&e->output, 1);
 427         buffer_put_char(&e->output,
 428             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 429 }
 430
 431 static void
 432 process_remove_all_identities(SocketEntry *e, int version)
 433 {
 434         Idtab *tab = idtab_lookup(version);
 435         Identity *id;
 436
 437         /* Loop over all identities and clear the keys. */
 438         for (id = TAILQ_FIRST(&tab->idlist); id;
 439             id = TAILQ_FIRST(&tab->idlist)) {
 440                 TAILQ_REMOVE(&tab->idlist, id, next);
 441                 free_identity(id);
 442         }
 443
 444         /* Mark that there are no identities. */
 445         tab->nentries = 0;
 446
 447         /* Send success. */
 448         buffer_put_int(&e->output, 1);
 449         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 450 }
 451
 452 /* removes expired keys and returns number of seconds until the next expiry */
 453 static time_t
 454 reaper(void)
 455 {
 456         time_t deadline = 0, now = monotime();
 457         Identity *id, *nxt;
 458         int version;
 459         Idtab *tab;
 460
 461         for (version = 1; version < 3; version++) {
 462                 tab = idtab_lookup(version);
 463                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 464                         nxt = TAILQ_NEXT(id, next);
 465                         if (id->death == 0)
 466                                 continue;
 467                         if (now >= id->death) {
 468                                 debug("expiring key '%s'", id->comment);
 469                                 TAILQ_REMOVE(&tab->idlist, id, next);
 470                                 free_identity(id);
 471                                 tab->nentries--;
 472                         } else
 473                                 deadline = (deadline == 0) ? id->death :
 474                                     MIN(deadline, id->death);
 475                 }
 476         }
 477         if (deadline == 0 || deadline <= now)
 478                 return 0;
 479         else
 480                 return (deadline - now);
 481 }
 482
 483 static void
 484 process_add_identity(SocketEntry *e, int version)
 485 {
 486         Idtab *tab = idtab_lookup(version);
 487         Identity *id;
 488         int type, success = 0, confirm = 0;
 489         char *comment;
 490         time_t death = 0;
 491         Key *k = NULL;
 492
 493         switch (version) {
 494         case 1:
 495                 k = key_new_private(KEY_RSA1);
 496                 (void) buffer_get_int(&e->request);             /* ignored */
 497                 buffer_get_bignum(&e->request, k->rsa->n);
 498                 buffer_get_bignum(&e->request, k->rsa->e);
 499                 buffer_get_bignum(&e->request, k->rsa->d);
 500                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 501
 502                 /* SSH and SSL have p and q swapped */
 503                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 504                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 505
 506                 /* Generate additional parameters */
 507                 rsa_generate_additional_parameters(k->rsa);
 508
 509                 /* enable blinding */
 510                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 511                         error("process_add_identity: RSA_blinding_on failed");
 512                         key_free(k);
 513                         goto send;
 514                 }
 515                 break;
 516         case 2:
 517                 k = key_private_deserialize(&e->request);
 518                 if (k == NULL) {
 519                         buffer_clear(&e->request);
 520                         goto send;
 521                 }
 522                 break;
 523         }
 524         comment = buffer_get_string(&e->request, NULL);
 525         if (k == NULL) {
 526                 free(comment);
 527                 goto send;
 528         }
 529         while (buffer_len(&e->request)) {
 530                 switch ((type = buffer_get_char(&e->request))) {
 531                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 532                         death = monotime() + buffer_get_int(&e->request);
 533                         break;
 534                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 535                         confirm = 1;
 536                         break;
 537                 default:
 538                         error("process_add_identity: "
 539                             "Unknown constraint type %d", type);
 540                         free(comment);
 541                         key_free(k);
 542                         goto send;
 543                 }
 544         }
 545         success = 1;
 546         if (lifetime && !death)
 547                 death = monotime() + lifetime;
 548         if ((id = lookup_identity(k, version)) == NULL) {
 549                 id = xcalloc(1, sizeof(Identity));
 550                 id->key = k;
 551                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 552                 /* Increment the number of identities. */
 553                 tab->nentries++;
 554         } else {
 555                 key_free(k);
 556                 free(id->comment);
 557         }
 558         id->comment = comment;
 559         id->death = death;
 560         id->confirm = confirm;
 561 send:
 562         buffer_put_int(&e->output, 1);
 563         buffer_put_char(&e->output,
 564             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 565 }
 566
 567 /* XXX todo: encrypt sensitive data with passphrase */
 568 static void
 569 process_lock_agent(SocketEntry *e, int lock)
 570 {
 571         int success = 0;
 572         char *passwd;
 573
 574         passwd = buffer_get_string(&e->request, NULL);
 575         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 576                 locked = 0;
 577                 explicit_bzero(lock_passwd, strlen(lock_passwd));
 578                 free(lock_passwd);
 579                 lock_passwd = NULL;
 580                 success = 1;
 581         } else if (!locked && lock) {
 582                 locked = 1;
 583                 lock_passwd = xstrdup(passwd);
 584                 success = 1;
 585         }
 586         explicit_bzero(passwd, strlen(passwd));
 587         free(passwd);
 588
 589         buffer_put_int(&e->output, 1);
 590         buffer_put_char(&e->output,
 591             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 592 }
 593
 594 static void
 595 no_identities(SocketEntry *e, u_int type)
 596 {
 597         Buffer msg;
 598
 599         buffer_init(&msg);
 600         buffer_put_char(&msg,
 601             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 602             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 603         buffer_put_int(&msg, 0);
 604         buffer_put_int(&e->output, buffer_len(&msg));
 605         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 606         buffer_free(&msg);
 607 }
 608
 609 #ifdef ENABLE_PKCS11
 610 static void
 611 process_add_smartcard_key(SocketEntry *e)
 612 {
 613         char *provider = NULL, *pin;
 614         int i, type, version, count = 0, success = 0, confirm = 0;
 615         time_t death = 0;
 616         Key **keys = NULL, *k;
 617         Identity *id;
 618         Idtab *tab;
 619
 620         provider = buffer_get_string(&e->request, NULL);
 621         pin = buffer_get_string(&e->request, NULL);
 622
 623         while (buffer_len(&e->request)) {
 624                 switch ((type = buffer_get_char(&e->request))) {
 625                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 626                         death = monotime() + buffer_get_int(&e->request);
 627                         break;
 628                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 629                         confirm = 1;
 630                         break;
 631                 default:
 632                         error("process_add_smartcard_key: "
 633                             "Unknown constraint type %d", type);
 634                         goto send;
 635                 }
 636         }
 637         if (lifetime && !death)
 638                 death = monotime() + lifetime;
 639
 640         count = pkcs11_add_provider(provider, pin, &keys);
 641         for (i = 0; i < count; i++) {
 642                 k = keys[i];
 643                 version = k->type == KEY_RSA1 ? 1 : 2;
 644                 tab = idtab_lookup(version);
 645                 if (lookup_identity(k, version) == NULL) {
 646                         id = xcalloc(1, sizeof(Identity));
 647                         id->key = k;
 648                         id->provider = xstrdup(provider);
 649                         id->comment = xstrdup(provider); /* XXX */
 650                         id->death = death;
 651                         id->confirm = confirm;
 652                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 653                         tab->nentries++;
 654                         success = 1;
 655                 } else {
 656                         key_free(k);
 657                 }
 658                 keys[i] = NULL;
 659         }
 660 send:
 661         free(pin);
 662         free(provider);
 663         free(keys);
 664         buffer_put_int(&e->output, 1);
 665         buffer_put_char(&e->output,
 666             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 667 }
 668
 669 static void
 670 process_remove_smartcard_key(SocketEntry *e)
 671 {
 672         char *provider = NULL, *pin = NULL;
 673         int version, success = 0;
 674         Identity *id, *nxt;
 675         Idtab *tab;
 676
 677         provider = buffer_get_string(&e->request, NULL);
 678         pin = buffer_get_string(&e->request, NULL);
 679         free(pin);
 680
 681         for (version = 1; version < 3; version++) {
 682                 tab = idtab_lookup(version);
 683                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 684                         nxt = TAILQ_NEXT(id, next);
 685                         /* Skip file--based keys */
 686                         if (id->provider == NULL)
 687                                 continue;
 688                         if (!strcmp(provider, id->provider)) {
 689                                 TAILQ_REMOVE(&tab->idlist, id, next);
 690                                 free_identity(id);
 691                                 tab->nentries--;
 692                         }
 693                 }
 694         }
 695         if (pkcs11_del_provider(provider) == 0)
 696                 success = 1;
 697         else
 698                 error("process_remove_smartcard_key:"
 699                     " pkcs11_del_provider failed");
 700         free(provider);
 701         buffer_put_int(&e->output, 1);
 702         buffer_put_char(&e->output,
 703             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 704 }
 705 #endif /* ENABLE_PKCS11 */
 706
 707 /* dispatch incoming messages */
 708
 709 static void
 710 process_message(SocketEntry *e)
 711 {
 712         u_int msg_len, type;
 713         u_char *cp;
 714
 715         if (buffer_len(&e->input) < 5)
 716                 return;         /* Incomplete message. */
 717         cp = buffer_ptr(&e->input);
 718         msg_len = get_u32(cp);
 719         if (msg_len > 256 * 1024) {
 720                 close_socket(e);
 721                 return;
 722         }
 723         if (buffer_len(&e->input) < msg_len + 4)
 724                 return;
 725
 726         /* move the current input to e->request */
 727         buffer_consume(&e->input, 4);
 728         buffer_clear(&e->request);
 729         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 730         buffer_consume(&e->input, msg_len);
 731         type = buffer_get_char(&e->request);
 732
 733         /* check wheter agent is locked */
 734         if (locked && type != SSH_AGENTC_UNLOCK) {
 735                 buffer_clear(&e->request);
 736                 switch (type) {
 737                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 738                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 739                         /* send empty lists */
 740                         no_identities(e, type);
 741                         break;
 742                 default:
 743                         /* send a fail message for all other request types */
 744                         buffer_put_int(&e->output, 1);
 745                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 746                 }
 747                 return;
 748         }
 749
 750         debug("type %d", type);
 751         switch (type) {
 752         case SSH_AGENTC_LOCK:
 753         case SSH_AGENTC_UNLOCK:
 754                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 755                 break;
 756         /* ssh1 */
 757         case SSH_AGENTC_RSA_CHALLENGE:
 758                 process_authentication_challenge1(e);
 759                 break;
 760         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 761                 process_request_identities(e, 1);
 762                 break;
 763         case SSH_AGENTC_ADD_RSA_IDENTITY:
 764         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 765                 process_add_identity(e, 1);
 766                 break;
 767         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 768                 process_remove_identity(e, 1);
 769                 break;
 770         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 771                 process_remove_all_identities(e, 1);
 772                 break;
 773         /* ssh2 */
 774         case SSH2_AGENTC_SIGN_REQUEST:
 775                 process_sign_request2(e);
 776                 break;
 777         case SSH2_AGENTC_REQUEST_IDENTITIES:
 778                 process_request_identities(e, 2);
 779                 break;
 780         case SSH2_AGENTC_ADD_IDENTITY:
 781         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 782                 process_add_identity(e, 2);
 783                 break;
 784         case SSH2_AGENTC_REMOVE_IDENTITY:
 785                 process_remove_identity(e, 2);
 786                 break;
 787         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 788                 process_remove_all_identities(e, 2);
 789                 break;
 790 #ifdef ENABLE_PKCS11
 791         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 792         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 793                 process_add_smartcard_key(e);
 794                 break;
 795         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 796                 process_remove_smartcard_key(e);
 797                 break;
 798 #endif /* ENABLE_PKCS11 */
 799         default:
 800                 /* Unknown message.  Respond with failure. */
 801                 error("Unknown message %d", type);
 802                 buffer_clear(&e->request);
 803                 buffer_put_int(&e->output, 1);
 804                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 805                 break;
 806         }
 807 }
 808
 809 static void
 810 new_socket(sock_type type, int fd)
 811 {
 812         u_int i, old_alloc, new_alloc;
 813
 814         if (type == AUTH_CONNECTION) {
 815                 debug("xcount %d -> %d", xcount, xcount + 1);
 816                 ++xcount;
 817         }
 818         set_nonblock(fd);
 819
 820         if (fd > max_fd)
 821                 max_fd = fd;
 822
 823         for (i = 0; i < sockets_alloc; i++)
 824                 if (sockets[i].type == AUTH_UNUSED) {
 825                         sockets[i].fd = fd;
 826                         buffer_init(&sockets[i].input);
 827                         buffer_init(&sockets[i].output);
 828                         buffer_init(&sockets[i].request);
 829                         sockets[i].type = type;
 830                         return;
 831                 }
 832         old_alloc = sockets_alloc;
 833         new_alloc = sockets_alloc + 10;
 834         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 835         for (i = old_alloc; i < new_alloc; i++)
 836                 sockets[i].type = AUTH_UNUSED;
 837         sockets_alloc = new_alloc;
 838         sockets[old_alloc].fd = fd;
 839         buffer_init(&sockets[old_alloc].input);
 840         buffer_init(&sockets[old_alloc].output);
 841         buffer_init(&sockets[old_alloc].request);
 842         sockets[old_alloc].type = type;
 843 }
 844
 845 static int
 846 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
 847     struct timeval **tvpp)
 848 {
 849         u_int i, sz;
 850         int n = 0;
 851         static struct timeval tv;
 852         time_t deadline;
 853
 854         for (i = 0; i < sockets_alloc; i++) {
 855                 switch (sockets[i].type) {
 856                 case AUTH_SOCKET:
 857                 case AUTH_CONNECTION:
 858                         n = MAX(n, sockets[i].fd);
 859                         break;
 860                 case AUTH_UNUSED:
 861                         break;
 862                 default:
 863                         fatal("Unknown socket type %d", sockets[i].type);
 864                         break;
 865                 }
 866         }
 867
 868         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 869         if (*fdrp == NULL || sz > *nallocp) {
 870                 free(*fdrp);
 871                 free(*fdwp);
 872                 *fdrp = xmalloc(sz);
 873                 *fdwp = xmalloc(sz);
 874                 *nallocp = sz;
 875         }
 876         if (n < *fdl)
 877                 debug("XXX shrink: %d < %d", n, *fdl);
 878         *fdl = n;
 879         memset(*fdrp, 0, sz);
 880         memset(*fdwp, 0, sz);
 881
 882         for (i = 0; i < sockets_alloc; i++) {
 883                 switch (sockets[i].type) {
 884                 case AUTH_SOCKET:
 885                 case AUTH_CONNECTION:
 886                         FD_SET(sockets[i].fd, *fdrp);
 887                         if (buffer_len(&sockets[i].output) > 0)
 888                                 FD_SET(sockets[i].fd, *fdwp);
 889                         break;
 890                 default:
 891                         break;
 892                 }
 893         }
 894         deadline = reaper();
 895         if (parent_alive_interval != 0)
 896                 deadline = (deadline == 0) ? parent_alive_interval :
 897                     MIN(deadline, parent_alive_interval);
 898         if (deadline == 0) {
 899                 *tvpp = NULL;
 900         } else {
 901                 tv.tv_sec = deadline;
 902                 tv.tv_usec = 0;
 903                 *tvpp = &tv;
 904         }
 905         return (1);
 906 }
 907
 908 static void
 909 after_select(fd_set *readset, fd_set *writeset)
 910 {
 911         struct sockaddr_un sunaddr;
 912         socklen_t slen;
 913         char buf[1024];
 914         int len, sock;
 915         u_int i, orig_alloc;
 916         uid_t euid;
 917         gid_t egid;
 918
 919         for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++)
 920                 switch (sockets[i].type) {
 921                 case AUTH_UNUSED:
 922                         break;
 923                 case AUTH_SOCKET:
 924                         if (FD_ISSET(sockets[i].fd, readset)) {
 925                                 slen = sizeof(sunaddr);
 926                                 sock = accept(sockets[i].fd,
 927                                     (struct sockaddr *)&sunaddr, &slen);
 928                                 if (sock < 0) {
 929                                         error("accept from AUTH_SOCKET: %s",
 930                                             strerror(errno));
 931                                         break;
 932                                 }
 933                                 if (getpeereid(sock, &euid, &egid) < 0) {
 934                                         error("getpeereid %d failed: %s",
 935                                             sock, strerror(errno));
 936                                         close(sock);
 937                                         break;
 938                                 }
 939                                 if ((euid != 0) && (getuid() != euid)) {
 940                                         error("uid mismatch: "
 941                                             "peer euid %u != uid %u",
 942                                             (u_int) euid, (u_int) getuid());
 943                                         close(sock);
 944                                         break;
 945                                 }
 946                                 new_socket(AUTH_CONNECTION, sock);
 947                         }
 948                         break;
 949                 case AUTH_CONNECTION:
 950                         if (buffer_len(&sockets[i].output) > 0 &&
 951                             FD_ISSET(sockets[i].fd, writeset)) {
 952                                 len = write(sockets[i].fd,
 953                                     buffer_ptr(&sockets[i].output),
 954                                     buffer_len(&sockets[i].output));
 955                                 if (len == -1 && (errno == EAGAIN ||
 956                                     errno == EWOULDBLOCK ||
 957                                     errno == EINTR))
 958                                         continue;
 959                                 if (len <= 0) {
 960                                         close_socket(&sockets[i]);
 961                                         break;
 962                                 }
 963                                 buffer_consume(&sockets[i].output, len);
 964                         }
 965                         if (FD_ISSET(sockets[i].fd, readset)) {
 966                                 len = read(sockets[i].fd, buf, sizeof(buf));
 967                                 if (len == -1 && (errno == EAGAIN ||
 968                                     errno == EWOULDBLOCK ||
 969                                     errno == EINTR))
 970                                         continue;
 971                                 if (len <= 0) {
 972                                         close_socket(&sockets[i]);
 973                                         break;
 974                                 }
 975                                 buffer_append(&sockets[i].input, buf, len);
 976                                 process_message(&sockets[i]);
 977                         }
 978                         break;
 979                 default:
 980                         fatal("Unknown type %d", sockets[i].type);
 981                 }
 982 }
 983
 984 static void
 985 cleanup_socket(void)
 986 {
 987         if (socket_name[0])
 988                 unlink(socket_name);
 989         if (socket_dir[0])
 990                 rmdir(socket_dir);
 991 }
 992
 993 void
 994 cleanup_exit(int i)
 995 {
 996         cleanup_socket();
 997         _exit(i);
 998 }
 999
1000 /*ARGSUSED*/
1001 static void
1002 cleanup_handler(int sig)
1003 {
1004         cleanup_socket();
1005 #ifdef ENABLE_PKCS11
1006         pkcs11_terminate();
1007 #endif
1008         _exit(2);
1009 }
1010
1011 static void
1012 check_parent_exists(void)
1013 {
1014         /*
1015          * If our parent has exited then getppid() will return (pid_t)1,
1016          * so testing for that should be safe.
1017          */
1018         if (parent_pid != -1 && getppid() != parent_pid) {
1019                 /* printf("Parent has died - Authentication agent exiting.\n"); */
1020                 cleanup_socket();
1021                 _exit(2);
1022         }
1023 }
1024
1025 static void
1026 usage(void)
1027 {
1028         fprintf(stderr, "usage: %s [options] [command [arg ...]]\n",
1029             __progname);
1030         fprintf(stderr, "Options:\n");
1031         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1032         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1033         fprintf(stderr, "  -k          Kill the current agent.\n");
1034         fprintf(stderr, "  -d          Debug mode.\n");
1035         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1036         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1037         fprintf(stderr, "  -x          Exit when the last client disconnects.\n");
1038         exit(1);
1039 }
1040
1041 int
1042 main(int ac, char **av)
1043 {
1044         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1045         int sock, fd, ch, result, saved_errno;
1046         u_int nalloc;
1047         char *shell, *format, *pidstr, *agentsocket = NULL;
1048         fd_set *readsetp = NULL, *writesetp = NULL;
1049         struct sockaddr_un sunaddr;
1050 #ifdef HAVE_SETRLIMIT
1051         struct rlimit rlim;
1052 #endif
1053         int prev_mask;
1054         extern int optind;
1055         extern char *optarg;
1056         pid_t pid;
1057         char pidstrbuf[1 + 3 * sizeof pid];
1058         struct timeval *tvp = NULL;
1059         size_t len;
1060
1061         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1062         sanitise_stdfd();
1063
1064         /* drop */
1065         setegid(getgid());
1066         setgid(getgid());
1067         setuid(geteuid());
1068
1069 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1070         /* Disable ptrace on Linux without sgid bit */
1071         prctl(PR_SET_DUMPABLE, 0);
1072 #endif
1073
1074         OpenSSL_add_all_algorithms();
1075
1076         __progname = ssh_get_progname(av[0]);
1077         seed_rng();
1078
1079         while ((ch = getopt(ac, av, "cdksa:t:x")) != -1) {
1080                 switch (ch) {
1081                 case 'c':
1082                         if (s_flag)
1083                                 usage();
1084                         c_flag++;
1085                         break;
1086                 case 'k':
1087                         k_flag++;
1088                         break;
1089                 case 's':
1090                         if (c_flag)
1091                                 usage();
1092                         s_flag++;
1093                         break;
1094                 case 'd':
1095                         if (d_flag)
1096                                 usage();
1097                         d_flag++;
1098                         break;
1099                 case 'a':
1100                         agentsocket = optarg;
1101                         break;
1102                 case 't':
1103                         if ((lifetime = convtime(optarg)) == -1) {
1104                                 fprintf(stderr, "Invalid lifetime\n");
1105                                 usage();
1106                         }
1107                         break;
1108                 case 'x':
1109                         xcount = 0;
1110                         break;
1111                 default:
1112                         usage();
1113                 }
1114         }
1115         ac -= optind;
1116         av += optind;
1117
1118         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1119                 usage();
1120
1121         if (ac == 0 && !c_flag && !s_flag) {
1122                 shell = getenv("SHELL");
1123                 if (shell != NULL && (len = strlen(shell)) > 2 &&
1124                     strncmp(shell + len - 3, "csh", 3) == 0)
1125                         c_flag = 1;
1126         }
1127         if (k_flag) {
1128                 const char *errstr = NULL;
1129
1130                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1131                 if (pidstr == NULL) {
1132                         fprintf(stderr, "%s not set, cannot kill agent\n",
1133                             SSH_AGENTPID_ENV_NAME);
1134                         exit(1);
1135                 }
1136                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1137                 if (errstr) {
1138                         fprintf(stderr,
1139                             "%s=\"%s\", which is not a good PID: %s\n",
1140                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1141                         exit(1);
1142                 }
1143                 if (kill(pid, SIGTERM) == -1) {
1144                         perror("kill");
1145                         exit(1);
1146                 }
1147                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1148                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1149                 printf(format, SSH_AGENTPID_ENV_NAME);
1150                 printf("echo Agent pid %ld killed;\n", (long)pid);
1151                 exit(0);
1152         }
1153         parent_pid = getpid();
1154
1155         if (agentsocket == NULL) {
1156                 /* Create private directory for agent socket */
1157                 mktemp_proto(socket_dir, sizeof(socket_dir));
1158                 if (mkdtemp(socket_dir) == NULL) {
1159                         perror("mkdtemp: private socket dir");
1160                         exit(1);
1161                 }
1162                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1163                     (long)parent_pid);
1164         } else {
1165                 /* Try to use specified agent socket */
1166                 socket_dir[0] = '\0';
1167                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1168         }
1169
1170         /*
1171          * Create socket early so it will exist before command gets run from
1172          * the parent.
1173          */
1174         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1175         if (sock < 0) {
1176                 perror("socket");
1177                 *socket_name = '\0'; /* Don't unlink any existing file */
1178                 cleanup_exit(1);
1179         }
1180         memset(&sunaddr, 0, sizeof(sunaddr));
1181         sunaddr.sun_family = AF_UNIX;
1182         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1183         prev_mask = umask(0177);
1184         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1185                 perror("bind");
1186                 *socket_name = '\0'; /* Don't unlink any existing file */
1187                 umask(prev_mask);
1188                 cleanup_exit(1);
1189         }
1190         umask(prev_mask);
1191         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1192                 perror("listen");
1193                 cleanup_exit(1);
1194         }
1195
1196         /*
1197          * Fork, and have the parent execute the command, if any, or present
1198          * the socket data.  The child continues as the authentication agent.
1199          */
1200         if (d_flag) {
1201                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1202                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1203                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1204                     SSH_AUTHSOCKET_ENV_NAME);
1205                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1206                 goto skip;
1207         }
1208         pid = fork();
1209         if (pid == -1) {
1210                 perror("fork");
1211                 cleanup_exit(1);
1212         }
1213         if (pid != 0) {         /* Parent - execute the given command. */
1214                 close(sock);
1215                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1216                 if (ac == 0) {
1217                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1218                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1219                             SSH_AUTHSOCKET_ENV_NAME);
1220                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1221                             SSH_AGENTPID_ENV_NAME);
1222                         printf("echo Agent pid %ld;\n", (long)pid);
1223                         exit(0);
1224                 }
1225                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1226                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1227                         perror("setenv");
1228                         exit(1);
1229                 }
1230                 execvp(av[0], av);
1231                 perror(av[0]);
1232                 exit(1);
1233         }
1234         /* child */
1235         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1236
1237         if (setsid() == -1) {
1238                 error("setsid: %s", strerror(errno));
1239                 cleanup_exit(1);
1240         }
1241
1242         (void)chdir("/");
1243         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1244                 /* XXX might close listen socket */
1245                 (void)dup2(fd, STDIN_FILENO);
1246                 (void)dup2(fd, STDOUT_FILENO);
1247                 (void)dup2(fd, STDERR_FILENO);
1248                 if (fd > 2)
1249                         close(fd);
1250         }
1251
1252 #ifdef HAVE_SETRLIMIT
1253         /* deny core dumps, since memory contains unencrypted private keys */
1254         rlim.rlim_cur = rlim.rlim_max = 0;
1255         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1256                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1257                 cleanup_exit(1);
1258         }
1259 #endif
1260
1261 skip:
1262
1263 #ifdef ENABLE_PKCS11
1264         pkcs11_init(0);
1265 #endif
1266         new_socket(AUTH_SOCKET, sock);
1267         if (ac > 0)
1268                 parent_alive_interval = 10;
1269         idtab_init();
1270         signal(SIGPIPE, SIG_IGN);
1271         signal(SIGINT, d_flag ? cleanup_handler : SIG_IGN);
1272         signal(SIGHUP, cleanup_handler);
1273         signal(SIGTERM, cleanup_handler);
1274         nalloc = 0;
1275
1276         while (1) {
1277                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1278                 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1279                 saved_errno = errno;
1280                 if (parent_alive_interval != 0)
1281                         check_parent_exists();
1282                 (void) reaper();        /* remove expired keys */
1283                 if (result < 0) {
1284                         if (saved_errno == EINTR)
1285                                 continue;
1286                         fatal("select: %s", strerror(saved_errno));
1287                 } else if (result > 0)
1288                         after_select(readsetp, writesetp);
1289         }
1290         /* NOTREACHED */
1291 }