ssh-agent.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * The authentication agent program.
   6  *
   7  * As far as I am concerned, the code I have written for this software
   8  * can be used freely for any purpose.  Any derived versions of this
   9  * software must be clearly marked as such, and if the derived work is
  10  * incompatible with the protocol description in the RFC file, it must be
  11  * called by a name other than "ssh" or "Secure Shell".
  12  *
  13  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  14  *
  15  * Redistribution and use in source and binary forms, with or without
  16  * modification, are permitted provided that the following conditions
  17  * are met:
  18  * 1. Redistributions of source code must retain the above copyright
  19  *    notice, this list of conditions and the following disclaimer.
  20  * 2. Redistributions in binary form must reproduce the above copyright
  21  *    notice, this list of conditions and the following disclaimer in the
  22  *    documentation and/or other materials provided with the distribution.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  27  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  28  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  29  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  30  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  31  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  32  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  33  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 #include "includes.h"
  37 #include "openbsd-compat/fake-queue.h"
  38 RCSID("$OpenBSD: ssh-agent.c,v 1.91 2002/06/11 05:46:20 mpech Exp $");
  39
  40 #include <openssl/evp.h>
  41 #include <openssl/md5.h>
  42
  43 #include "ssh.h"
  44 #include "rsa.h"
  45 #include "buffer.h"
  46 #include "bufaux.h"
  47 #include "xmalloc.h"
  48 #include "getput.h"
  49 #include "key.h"
  50 #include "authfd.h"
  51 #include "compat.h"
  52 #include "log.h"
  53
  54 #ifdef SMARTCARD
  55 #include "scard.h"
  56 #endif
  57
  58 typedef enum {
  59         AUTH_UNUSED,
  60         AUTH_SOCKET,
  61         AUTH_CONNECTION
  62 } sock_type;
  63
  64 typedef struct {
  65         int fd;
  66         sock_type type;
  67         Buffer input;
  68         Buffer output;
  69         Buffer request;
  70 } SocketEntry;
  71
  72 u_int sockets_alloc = 0;
  73 SocketEntry *sockets = NULL;
  74
  75 typedef struct identity {
  76         TAILQ_ENTRY(identity) next;
  77         Key *key;
  78         char *comment;
  79         u_int death;
  80 } Identity;
  81
  82 typedef struct {
  83         int nentries;
  84         TAILQ_HEAD(idqueue, identity) idlist;
  85 } Idtab;
  86
  87 /* private key table, one per protocol version */
  88 Idtab idtable[3];
  89
  90 int max_fd = 0;
  91
  92 /* pid of shell == parent of agent */
  93 pid_t parent_pid = -1;
  94
  95 /* pathname and directory for AUTH_SOCKET */
  96 char socket_name[1024];
  97 char socket_dir[1024];
  98
  99 /* locking */
 100 int locked = 0;
 101 char *lock_passwd = NULL;
 102
 103 #ifdef HAVE___PROGNAME
 104 extern char *__progname;
 105 #else
 106 char *__progname;
 107 #endif
 108
 109 static void
 110 idtab_init(void)
 111 {
 112         int i;
 113         for (i = 0; i <=2; i++) {
 114                 TAILQ_INIT(&idtable[i].idlist);
 115                 idtable[i].nentries = 0;
 116         }
 117 }
 118
 119 /* return private key table for requested protocol version */
 120 static Idtab *
 121 idtab_lookup(int version)
 122 {
 123         if (version < 1 || version > 2)
 124                 fatal("internal error, bad protocol version %d", version);
 125         return &idtable[version];
 126 }
 127
 128 static void
 129 free_identity(Identity *id)
 130 {
 131         key_free(id->key);
 132         xfree(id->comment);
 133         xfree(id);
 134 }
 135
 136 /* return matching private key for given public key */
 137 static Identity *
 138 lookup_identity(Key *key, int version)
 139 {
 140         Identity *id;
 141
 142         Idtab *tab = idtab_lookup(version);
 143         TAILQ_FOREACH(id, &tab->idlist, next) {
 144                 if (key_equal(key, id->key))
 145                         return (id);
 146         }
 147         return (NULL);
 148 }
 149
 150 /* send list of supported public keys to 'client' */
 151 static void
 152 process_request_identities(SocketEntry *e, int version)
 153 {
 154         Idtab *tab = idtab_lookup(version);
 155         Buffer msg;
 156         Identity *id;
 157
 158         buffer_init(&msg);
 159         buffer_put_char(&msg, (version == 1) ?
 160             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 161         buffer_put_int(&msg, tab->nentries);
 162         TAILQ_FOREACH(id, &tab->idlist, next) {
 163                 if (id->key->type == KEY_RSA1) {
 164                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 165                         buffer_put_bignum(&msg, id->key->rsa->e);
 166                         buffer_put_bignum(&msg, id->key->rsa->n);
 167                 } else {
 168                         u_char *blob;
 169                         u_int blen;
 170                         key_to_blob(id->key, &blob, &blen);
 171                         buffer_put_string(&msg, blob, blen);
 172                         xfree(blob);
 173                 }
 174                 buffer_put_cstring(&msg, id->comment);
 175         }
 176         buffer_put_int(&e->output, buffer_len(&msg));
 177         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 178         buffer_free(&msg);
 179 }
 180
 181 /* ssh1 only */
 182 static void
 183 process_authentication_challenge1(SocketEntry *e)
 184 {
 185         Identity *id;
 186         Key *key;
 187         BIGNUM *challenge;
 188         int i, len;
 189         Buffer msg;
 190         MD5_CTX md;
 191         u_char buf[32], mdbuf[16], session_id[16];
 192         u_int response_type;
 193
 194         buffer_init(&msg);
 195         key = key_new(KEY_RSA1);
 196         if ((challenge = BN_new()) == NULL)
 197                 fatal("process_authentication_challenge1: BN_new failed");
 198
 199         buffer_get_int(&e->request);                            /* ignored */
 200         buffer_get_bignum(&e->request, key->rsa->e);
 201         buffer_get_bignum(&e->request, key->rsa->n);
 202         buffer_get_bignum(&e->request, challenge);
 203
 204         /* Only protocol 1.1 is supported */
 205         if (buffer_len(&e->request) == 0)
 206                 goto failure;
 207         buffer_get(&e->request, session_id, 16);
 208         response_type = buffer_get_int(&e->request);
 209         if (response_type != 1)
 210                 goto failure;
 211
 212         id = lookup_identity(key, 1);
 213         if (id != NULL) {
 214                 Key *private = id->key;
 215                 /* Decrypt the challenge using the private key. */
 216                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 217                         goto failure;
 218
 219                 /* The response is MD5 of decrypted challenge plus session id. */
 220                 len = BN_num_bytes(challenge);
 221                 if (len <= 0 || len > 32) {
 222                         log("process_authentication_challenge: bad challenge length %d", len);
 223                         goto failure;
 224                 }
 225                 memset(buf, 0, 32);
 226                 BN_bn2bin(challenge, buf + 32 - len);
 227                 MD5_Init(&md);
 228                 MD5_Update(&md, buf, 32);
 229                 MD5_Update(&md, session_id, 16);
 230                 MD5_Final(mdbuf, &md);
 231
 232                 /* Send the response. */
 233                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 234                 for (i = 0; i < 16; i++)
 235                         buffer_put_char(&msg, mdbuf[i]);
 236                 goto send;
 237         }
 238
 239 failure:
 240         /* Unknown identity or protocol error.  Send failure. */
 241         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 242 send:
 243         buffer_put_int(&e->output, buffer_len(&msg));
 244         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 245         key_free(key);
 246         BN_clear_free(challenge);
 247         buffer_free(&msg);
 248 }
 249
 250 /* ssh2 only */
 251 static void
 252 process_sign_request2(SocketEntry *e)
 253 {
 254         extern int datafellows;
 255         Key *key;
 256         u_char *blob, *data, *signature = NULL;
 257         u_int blen, dlen, slen = 0;
 258         int flags;
 259         Buffer msg;
 260         int ok = -1;
 261
 262         datafellows = 0;
 263
 264         blob = buffer_get_string(&e->request, &blen);
 265         data = buffer_get_string(&e->request, &dlen);
 266
 267         flags = buffer_get_int(&e->request);
 268         if (flags & SSH_AGENT_OLD_SIGNATURE)
 269                 datafellows = SSH_BUG_SIGBLOB;
 270
 271         key = key_from_blob(blob, blen);
 272         if (key != NULL) {
 273                 Identity *id = lookup_identity(key, 2);
 274                 if (id != NULL)
 275                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 276         }
 277         key_free(key);
 278         buffer_init(&msg);
 279         if (ok == 0) {
 280                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 281                 buffer_put_string(&msg, signature, slen);
 282         } else {
 283                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 284         }
 285         buffer_put_int(&e->output, buffer_len(&msg));
 286         buffer_append(&e->output, buffer_ptr(&msg),
 287             buffer_len(&msg));
 288         buffer_free(&msg);
 289         xfree(data);
 290         xfree(blob);
 291         if (signature != NULL)
 292                 xfree(signature);
 293 }
 294
 295 /* shared */
 296 static void
 297 process_remove_identity(SocketEntry *e, int version)
 298 {
 299         Key *key = NULL;
 300         u_char *blob;
 301         u_int blen;
 302         u_int bits;
 303         int success = 0;
 304
 305         switch (version) {
 306         case 1:
 307                 key = key_new(KEY_RSA1);
 308                 bits = buffer_get_int(&e->request);
 309                 buffer_get_bignum(&e->request, key->rsa->e);
 310                 buffer_get_bignum(&e->request, key->rsa->n);
 311
 312                 if (bits != key_size(key))
 313                         log("Warning: identity keysize mismatch: actual %d, announced %d",
 314                             key_size(key), bits);
 315                 break;
 316         case 2:
 317                 blob = buffer_get_string(&e->request, &blen);
 318                 key = key_from_blob(blob, blen);
 319                 xfree(blob);
 320                 break;
 321         }
 322         if (key != NULL) {
 323                 Identity *id = lookup_identity(key, version);
 324                 if (id != NULL) {
 325                         /*
 326                          * We have this key.  Free the old key.  Since we
 327                          * don\'t want to leave empty slots in the middle of
 328                          * the array, we actually free the key there and move
 329                          * all the entries between the empty slot and the end
 330                          * of the array.
 331                          */
 332                         Idtab *tab = idtab_lookup(version);
 333                         if (tab->nentries < 1)
 334                                 fatal("process_remove_identity: "
 335                                     "internal error: tab->nentries %d",
 336                                     tab->nentries);
 337                         TAILQ_REMOVE(&tab->idlist, id, next);
 338                         free_identity(id);
 339                         tab->nentries--;
 340                         success = 1;
 341                 }
 342                 key_free(key);
 343         }
 344         buffer_put_int(&e->output, 1);
 345         buffer_put_char(&e->output,
 346             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 347 }
 348
 349 static void
 350 process_remove_all_identities(SocketEntry *e, int version)
 351 {
 352         Idtab *tab = idtab_lookup(version);
 353         Identity *id;
 354
 355         /* Loop over all identities and clear the keys. */
 356         for (id = TAILQ_FIRST(&tab->idlist); id;
 357             id = TAILQ_FIRST(&tab->idlist)) {
 358                 TAILQ_REMOVE(&tab->idlist, id, next);
 359                 free_identity(id);
 360         }
 361
 362         /* Mark that there are no identities. */
 363         tab->nentries = 0;
 364
 365         /* Send success. */
 366         buffer_put_int(&e->output, 1);
 367         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 368         return;
 369 }
 370
 371 static void
 372 reaper(void)
 373 {
 374         Idtab *tab;
 375         Identity *id, *nxt;
 376         int version;
 377         u_int now = time(NULL);
 378
 379         for (version = 1; version < 3; version++) {
 380                 tab = idtab_lookup(version);
 381                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 382                         nxt = TAILQ_NEXT(id, next);
 383                         if (id->death != 0 && now >= id->death) {
 384                                 TAILQ_REMOVE(&tab->idlist, id, next);
 385                                 free_identity(id);
 386                                 tab->nentries--;
 387                         }
 388                 }
 389         }
 390 }
 391
 392 static void
 393 process_add_identity(SocketEntry *e, int version)
 394 {
 395         Key *k = NULL;
 396         char *type_name;
 397         char *comment;
 398         int type, success = 0;
 399         Idtab *tab = idtab_lookup(version);
 400
 401         switch (version) {
 402         case 1:
 403                 k = key_new_private(KEY_RSA1);
 404                 buffer_get_int(&e->request);                    /* ignored */
 405                 buffer_get_bignum(&e->request, k->rsa->n);
 406                 buffer_get_bignum(&e->request, k->rsa->e);
 407                 buffer_get_bignum(&e->request, k->rsa->d);
 408                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 409
 410                 /* SSH and SSL have p and q swapped */
 411                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 412                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 413
 414                 /* Generate additional parameters */
 415                 rsa_generate_additional_parameters(k->rsa);
 416                 break;
 417         case 2:
 418                 type_name = buffer_get_string(&e->request, NULL);
 419                 type = key_type_from_name(type_name);
 420                 xfree(type_name);
 421                 switch (type) {
 422                 case KEY_DSA:
 423                         k = key_new_private(type);
 424                         buffer_get_bignum2(&e->request, k->dsa->p);
 425                         buffer_get_bignum2(&e->request, k->dsa->q);
 426                         buffer_get_bignum2(&e->request, k->dsa->g);
 427                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 428                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 429                         break;
 430                 case KEY_RSA:
 431                         k = key_new_private(type);
 432                         buffer_get_bignum2(&e->request, k->rsa->n);
 433                         buffer_get_bignum2(&e->request, k->rsa->e);
 434                         buffer_get_bignum2(&e->request, k->rsa->d);
 435                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 436                         buffer_get_bignum2(&e->request, k->rsa->p);
 437                         buffer_get_bignum2(&e->request, k->rsa->q);
 438
 439                         /* Generate additional parameters */
 440                         rsa_generate_additional_parameters(k->rsa);
 441                         break;
 442                 default:
 443                         buffer_clear(&e->request);
 444                         goto send;
 445                 }
 446                 break;
 447         }
 448         comment = buffer_get_string(&e->request, NULL);
 449         if (k == NULL) {
 450                 xfree(comment);
 451                 goto send;
 452         }
 453         success = 1;
 454         if (lookup_identity(k, version) == NULL) {
 455                 Identity *id = xmalloc(sizeof(Identity));
 456                 id->key = k;
 457                 id->comment = comment;
 458                 id->death = 0;
 459                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 460                 /* Increment the number of identities. */
 461                 tab->nentries++;
 462         } else {
 463                 key_free(k);
 464                 xfree(comment);
 465         }
 466 send:
 467         buffer_put_int(&e->output, 1);
 468         buffer_put_char(&e->output,
 469             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 470 }
 471
 472 static void
 473 process_lifetime_identity(SocketEntry *e, int version)
 474 {
 475         Key *key = NULL;
 476         u_char *blob;
 477         u_int blen, bits, death;
 478         int success = 0;
 479
 480         death = time(NULL) + buffer_get_int(&e->request);
 481
 482         switch (version) {
 483         case 1:
 484                 key = key_new(KEY_RSA1);
 485                 bits = buffer_get_int(&e->request);
 486                 buffer_get_bignum(&e->request, key->rsa->e);
 487                 buffer_get_bignum(&e->request, key->rsa->n);
 488
 489                 break;
 490         case 2:
 491                 blob = buffer_get_string(&e->request, &blen);
 492                 key = key_from_blob(blob, blen);
 493                 xfree(blob);
 494                 break;
 495         }
 496         if (key != NULL) {
 497                 Identity *id = lookup_identity(key, version);
 498                 if (id != NULL && id->death == 0) {
 499                         id->death = death;
 500                         success = 1;
 501                 }
 502                 key_free(key);
 503         }
 504         buffer_put_int(&e->output, 1);
 505         buffer_put_char(&e->output,
 506             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 507 }
 508
 509 /* XXX todo: encrypt sensitive data with passphrase */
 510 static void
 511 process_lock_agent(SocketEntry *e, int lock)
 512 {
 513         char *passwd;
 514         int success = 0;
 515
 516         passwd = buffer_get_string(&e->request, NULL);
 517         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 518                 locked = 0;
 519                 memset(lock_passwd, 0, strlen(lock_passwd));
 520                 xfree(lock_passwd);
 521                 lock_passwd = NULL;
 522                 success = 1;
 523         } else if (!locked && lock) {
 524                 locked = 1;
 525                 lock_passwd = xstrdup(passwd);
 526                 success = 1;
 527         }
 528         memset(passwd, 0, strlen(passwd));
 529         xfree(passwd);
 530
 531         buffer_put_int(&e->output, 1);
 532         buffer_put_char(&e->output,
 533             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 534         return;
 535 }
 536
 537 static void
 538 no_identities(SocketEntry *e, u_int type)
 539 {
 540         Buffer msg;
 541
 542         buffer_init(&msg);
 543         buffer_put_char(&msg,
 544             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 545             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 546         buffer_put_int(&msg, 0);
 547         buffer_put_int(&e->output, buffer_len(&msg));
 548         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 549         buffer_free(&msg);
 550 }
 551
 552 #ifdef SMARTCARD
 553 static void
 554 process_add_smartcard_key (SocketEntry *e)
 555 {
 556         Identity *id;
 557         Idtab *tab;
 558         Key **keys, *k;
 559         char *sc_reader_id = NULL, *pin;
 560         int i, version, success = 0;
 561
 562         sc_reader_id = buffer_get_string(&e->request, NULL);
 563         pin = buffer_get_string(&e->request, NULL);
 564         keys = sc_get_keys(sc_reader_id, pin);
 565         xfree(sc_reader_id);
 566         xfree(pin);
 567
 568         if (keys == NULL || keys[0] == NULL) {
 569                 error("sc_get_keys failed");
 570                 goto send;
 571         }
 572         for (i = 0; keys[i] != NULL; i++) {
 573                 k = keys[i];
 574                 version = k->type == KEY_RSA1 ? 1 : 2;
 575                 tab = idtab_lookup(version);
 576                 if (lookup_identity(k, version) == NULL) {
 577                         id = xmalloc(sizeof(Identity));
 578                         id->key = k;
 579                         id->comment = xstrdup("smartcard key");
 580                         id->death = 0;
 581                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 582                         tab->nentries++;
 583                         success = 1;
 584                 } else {
 585                         key_free(k);
 586                 }
 587                 keys[i] = NULL;
 588         }
 589         xfree(keys);
 590 send:
 591         buffer_put_int(&e->output, 1);
 592         buffer_put_char(&e->output,
 593             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 594 }
 595
 596 static void
 597 process_remove_smartcard_key(SocketEntry *e)
 598 {
 599         Identity *id;
 600         Idtab *tab;
 601         Key **keys, *k = NULL;
 602         char *sc_reader_id = NULL, *pin;
 603         int i, version, success = 0;
 604
 605         sc_reader_id = buffer_get_string(&e->request, NULL);
 606         pin = buffer_get_string(&e->request, NULL);
 607         keys = sc_get_keys(sc_reader_id, pin);
 608         xfree(sc_reader_id);
 609         xfree(pin);
 610
 611         if (keys == NULL || keys[0] == NULL) {
 612                 error("sc_get_keys failed");
 613                 goto send;
 614         }
 615         for (i = 0; keys[i] != NULL; i++) {
 616                 k = keys[i];
 617                 version = k->type == KEY_RSA1 ? 1 : 2;
 618                 if ((id = lookup_identity(k, version)) != NULL) {
 619                         tab = idtab_lookup(version);
 620                         TAILQ_REMOVE(&tab->idlist, id, next);
 621                         tab->nentries--;
 622                         free_identity(id);
 623                         success = 1;
 624                 }
 625                 key_free(k);
 626                 keys[i] = NULL;
 627         }
 628         xfree(keys);
 629 send:
 630         buffer_put_int(&e->output, 1);
 631         buffer_put_char(&e->output,
 632             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 633 }
 634 #endif /* SMARTCARD */
 635
 636 /* dispatch incoming messages */
 637
 638 static void
 639 process_message(SocketEntry *e)
 640 {
 641         u_int msg_len;
 642         u_int type;
 643         u_char *cp;
 644
 645         /* kill dead keys */
 646         reaper();
 647
 648         if (buffer_len(&e->input) < 5)
 649                 return;         /* Incomplete message. */
 650         cp = buffer_ptr(&e->input);
 651         msg_len = GET_32BIT(cp);
 652         if (msg_len > 256 * 1024) {
 653                 shutdown(e->fd, SHUT_RDWR);
 654                 close(e->fd);
 655                 e->type = AUTH_UNUSED;
 656                 buffer_free(&e->input);
 657                 buffer_free(&e->output);
 658                 buffer_free(&e->request);
 659                 return;
 660         }
 661         if (buffer_len(&e->input) < msg_len + 4)
 662                 return;
 663
 664         /* move the current input to e->request */
 665         buffer_consume(&e->input, 4);
 666         buffer_clear(&e->request);
 667         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 668         buffer_consume(&e->input, msg_len);
 669         type = buffer_get_char(&e->request);
 670
 671         /* check wheter agent is locked */
 672         if (locked && type != SSH_AGENTC_UNLOCK) {
 673                 buffer_clear(&e->request);
 674                 switch (type) {
 675                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 676                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 677                         /* send empty lists */
 678                         no_identities(e, type);
 679                         break;
 680                 default:
 681                         /* send a fail message for all other request types */
 682                         buffer_put_int(&e->output, 1);
 683                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 684                 }
 685                 return;
 686         }
 687
 688         debug("type %d", type);
 689         switch (type) {
 690         case SSH_AGENTC_LOCK:
 691         case SSH_AGENTC_UNLOCK:
 692                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 693                 break;
 694         /* ssh1 */
 695         case SSH_AGENTC_RSA_CHALLENGE:
 696                 process_authentication_challenge1(e);
 697                 break;
 698         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 699                 process_request_identities(e, 1);
 700                 break;
 701         case SSH_AGENTC_ADD_RSA_IDENTITY:
 702                 process_add_identity(e, 1);
 703                 break;
 704         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 705                 process_remove_identity(e, 1);
 706                 break;
 707         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 708                 process_remove_all_identities(e, 1);
 709                 break;
 710         case SSH_AGENTC_LIFETIME_IDENTITY1:
 711                 process_lifetime_identity(e, 1);
 712                 break;
 713         /* ssh2 */
 714         case SSH2_AGENTC_SIGN_REQUEST:
 715                 process_sign_request2(e);
 716                 break;
 717         case SSH2_AGENTC_REQUEST_IDENTITIES:
 718                 process_request_identities(e, 2);
 719                 break;
 720         case SSH2_AGENTC_ADD_IDENTITY:
 721                 process_add_identity(e, 2);
 722                 break;
 723         case SSH2_AGENTC_REMOVE_IDENTITY:
 724                 process_remove_identity(e, 2);
 725                 break;
 726         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 727                 process_remove_all_identities(e, 2);
 728                 break;
 729         case SSH_AGENTC_LIFETIME_IDENTITY:
 730                 process_lifetime_identity(e, 2);
 731                 break;
 732 #ifdef SMARTCARD
 733         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 734                 process_add_smartcard_key(e);
 735                 break;
 736         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 737                 process_remove_smartcard_key(e);
 738                 break;
 739 #endif /* SMARTCARD */
 740         default:
 741                 /* Unknown message.  Respond with failure. */
 742                 error("Unknown message %d", type);
 743                 buffer_clear(&e->request);
 744                 buffer_put_int(&e->output, 1);
 745                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 746                 break;
 747         }
 748 }
 749
 750 static void
 751 new_socket(sock_type type, int fd)
 752 {
 753         u_int i, old_alloc;
 754         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 755                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 756
 757         if (fd > max_fd)
 758                 max_fd = fd;
 759
 760         for (i = 0; i < sockets_alloc; i++)
 761                 if (sockets[i].type == AUTH_UNUSED) {
 762                         sockets[i].fd = fd;
 763                         sockets[i].type = type;
 764                         buffer_init(&sockets[i].input);
 765                         buffer_init(&sockets[i].output);
 766                         buffer_init(&sockets[i].request);
 767                         return;
 768                 }
 769         old_alloc = sockets_alloc;
 770         sockets_alloc += 10;
 771         if (sockets)
 772                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 773         else
 774                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 775         for (i = old_alloc; i < sockets_alloc; i++)
 776                 sockets[i].type = AUTH_UNUSED;
 777         sockets[old_alloc].type = type;
 778         sockets[old_alloc].fd = fd;
 779         buffer_init(&sockets[old_alloc].input);
 780         buffer_init(&sockets[old_alloc].output);
 781         buffer_init(&sockets[old_alloc].request);
 782 }
 783
 784 static int
 785 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 786 {
 787         u_int i, sz;
 788         int n = 0;
 789
 790         for (i = 0; i < sockets_alloc; i++) {
 791                 switch (sockets[i].type) {
 792                 case AUTH_SOCKET:
 793                 case AUTH_CONNECTION:
 794                         n = MAX(n, sockets[i].fd);
 795                         break;
 796                 case AUTH_UNUSED:
 797                         break;
 798                 default:
 799                         fatal("Unknown socket type %d", sockets[i].type);
 800                         break;
 801                 }
 802         }
 803
 804         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 805         if (*fdrp == NULL || sz > *nallocp) {
 806                 if (*fdrp)
 807                         xfree(*fdrp);
 808                 if (*fdwp)
 809                         xfree(*fdwp);
 810                 *fdrp = xmalloc(sz);
 811                 *fdwp = xmalloc(sz);
 812                 *nallocp = sz;
 813         }
 814         if (n < *fdl)
 815                 debug("XXX shrink: %d < %d", n, *fdl);
 816         *fdl = n;
 817         memset(*fdrp, 0, sz);
 818         memset(*fdwp, 0, sz);
 819
 820         for (i = 0; i < sockets_alloc; i++) {
 821                 switch (sockets[i].type) {
 822                 case AUTH_SOCKET:
 823                 case AUTH_CONNECTION:
 824                         FD_SET(sockets[i].fd, *fdrp);
 825                         if (buffer_len(&sockets[i].output) > 0)
 826                                 FD_SET(sockets[i].fd, *fdwp);
 827                         break;
 828                 default:
 829                         break;
 830                 }
 831         }
 832         return (1);
 833 }
 834
 835 static void
 836 after_select(fd_set *readset, fd_set *writeset)
 837 {
 838         u_int i;
 839         int len, sock;
 840         socklen_t slen;
 841         char buf[1024];
 842         struct sockaddr_un sunaddr;
 843
 844         for (i = 0; i < sockets_alloc; i++)
 845                 switch (sockets[i].type) {
 846                 case AUTH_UNUSED:
 847                         break;
 848                 case AUTH_SOCKET:
 849                         if (FD_ISSET(sockets[i].fd, readset)) {
 850                                 slen = sizeof(sunaddr);
 851                                 sock = accept(sockets[i].fd,
 852                                     (struct sockaddr *) &sunaddr, &slen);
 853                                 if (sock < 0) {
 854                                         error("accept from AUTH_SOCKET: %s",
 855                                             strerror(errno));
 856                                         break;
 857                                 }
 858                                 new_socket(AUTH_CONNECTION, sock);
 859                         }
 860                         break;
 861                 case AUTH_CONNECTION:
 862                         if (buffer_len(&sockets[i].output) > 0 &&
 863                             FD_ISSET(sockets[i].fd, writeset)) {
 864                                 do {
 865                                         len = write(sockets[i].fd,
 866                                             buffer_ptr(&sockets[i].output),
 867                                             buffer_len(&sockets[i].output));
 868                                         if (len == -1 && (errno == EAGAIN ||
 869                                             errno == EINTR))
 870                                                 continue;
 871                                         break;
 872                                 } while (1);
 873                                 if (len <= 0) {
 874                                         shutdown(sockets[i].fd, SHUT_RDWR);
 875                                         close(sockets[i].fd);
 876                                         sockets[i].type = AUTH_UNUSED;
 877                                         buffer_free(&sockets[i].input);
 878                                         buffer_free(&sockets[i].output);
 879                                         buffer_free(&sockets[i].request);
 880                                         break;
 881                                 }
 882                                 buffer_consume(&sockets[i].output, len);
 883                         }
 884                         if (FD_ISSET(sockets[i].fd, readset)) {
 885                                 do {
 886                                         len = read(sockets[i].fd, buf, sizeof(buf));
 887                                         if (len == -1 && (errno == EAGAIN ||
 888                                             errno == EINTR))
 889                                                 continue;
 890                                         break;
 891                                 } while (1);
 892                                 if (len <= 0) {
 893                                         shutdown(sockets[i].fd, SHUT_RDWR);
 894                                         close(sockets[i].fd);
 895                                         sockets[i].type = AUTH_UNUSED;
 896                                         buffer_free(&sockets[i].input);
 897                                         buffer_free(&sockets[i].output);
 898                                         buffer_free(&sockets[i].request);
 899                                         break;
 900                                 }
 901                                 buffer_append(&sockets[i].input, buf, len);
 902                                 process_message(&sockets[i]);
 903                         }
 904                         break;
 905                 default:
 906                         fatal("Unknown type %d", sockets[i].type);
 907                 }
 908 }
 909
 910 static void
 911 cleanup_socket(void *p)
 912 {
 913         if (socket_name[0])
 914                 unlink(socket_name);
 915         if (socket_dir[0])
 916                 rmdir(socket_dir);
 917 }
 918
 919 static void
 920 cleanup_exit(int i)
 921 {
 922         cleanup_socket(NULL);
 923         exit(i);
 924 }
 925
 926 static void
 927 cleanup_handler(int sig)
 928 {
 929         cleanup_socket(NULL);
 930         _exit(2);
 931 }
 932
 933 static void
 934 check_parent_exists(int sig)
 935 {
 936         int save_errno = errno;
 937
 938         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 939                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 940                 cleanup_handler(sig); /* safe */
 941         }
 942         signal(SIGALRM, check_parent_exists);
 943         alarm(10);
 944         errno = save_errno;
 945 }
 946
 947 static void
 948 usage(void)
 949 {
 950         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 951             __progname);
 952         fprintf(stderr, "Options:\n");
 953         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 954         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 955         fprintf(stderr, "  -k          Kill the current agent.\n");
 956         fprintf(stderr, "  -d          Debug mode.\n");
 957         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 958         exit(1);
 959 }
 960
 961 int
 962 main(int ac, char **av)
 963 {
 964         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 965         struct sockaddr_un sunaddr;
 966 #ifdef HAVE_SETRLIMIT
 967         struct rlimit rlim;
 968 #endif
 969 #ifdef HAVE_CYGWIN
 970         int prev_mask;
 971 #endif
 972         pid_t pid;
 973         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 974         char *agentsocket = NULL;
 975         extern int optind;
 976         fd_set *readsetp = NULL, *writesetp = NULL;
 977
 978         SSLeay_add_all_algorithms();
 979
 980         __progname = get_progname(av[0]);
 981         init_rng();
 982         seed_rng();
 983
 984 #ifdef __GNU_LIBRARY__
 985         while ((ch = getopt(ac, av, "+cdksa:")) != -1) {
 986 #else /* __GNU_LIBRARY__ */
 987         while ((ch = getopt(ac, av, "cdksa:")) != -1) {
 988 #endif /* __GNU_LIBRARY__ */
 989                 switch (ch) {
 990                 case 'c':
 991                         if (s_flag)
 992                                 usage();
 993                         c_flag++;
 994                         break;
 995                 case 'k':
 996                         k_flag++;
 997                         break;
 998                 case 's':
 999                         if (c_flag)
1000                                 usage();
1001                         s_flag++;
1002                         break;
1003                 case 'd':
1004                         if (d_flag)
1005                                 usage();
1006                         d_flag++;
1007                         break;
1008                 case 'a':
1009                         agentsocket = optarg;
1010                         break;
1011                 default:
1012                         usage();
1013                 }
1014         }
1015         ac -= optind;
1016         av += optind;
1017
1018         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1019                 usage();
1020
1021         if (ac == 0 && !c_flag && !s_flag) {
1022                 shell = getenv("SHELL");
1023                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1024                         c_flag = 1;
1025         }
1026         if (k_flag) {
1027                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1028                 if (pidstr == NULL) {
1029                         fprintf(stderr, "%s not set, cannot kill agent\n",
1030                             SSH_AGENTPID_ENV_NAME);
1031                         exit(1);
1032                 }
1033                 pid = atoi(pidstr);
1034                 if (pid < 1) {
1035                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
1036                             SSH_AGENTPID_ENV_NAME, pidstr);
1037                         exit(1);
1038                 }
1039                 if (kill(pid, SIGTERM) == -1) {
1040                         perror("kill");
1041                         exit(1);
1042                 }
1043                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1044                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1045                 printf(format, SSH_AGENTPID_ENV_NAME);
1046                 printf("echo Agent pid %ld killed;\n", (long)pid);
1047                 exit(0);
1048         }
1049         parent_pid = getpid();
1050
1051         if (agentsocket == NULL) {
1052                 /* Create private directory for agent socket */
1053                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
1054                 if (mkdtemp(socket_dir) == NULL) {
1055                         perror("mkdtemp: private socket dir");
1056                         exit(1);
1057                 }
1058                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1059                     (long)parent_pid);
1060         } else {
1061                 /* Try to use specified agent socket */
1062                 socket_dir[0] = '\0';
1063                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1064         }
1065
1066         /*
1067          * Create socket early so it will exist before command gets run from
1068          * the parent.
1069          */
1070         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1071         if (sock < 0) {
1072                 perror("socket");
1073                 cleanup_exit(1);
1074         }
1075         memset(&sunaddr, 0, sizeof(sunaddr));
1076         sunaddr.sun_family = AF_UNIX;
1077         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1078 #ifdef HAVE_CYGWIN
1079         prev_mask = umask(0177);
1080 #endif
1081         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1082                 perror("bind");
1083 #ifdef HAVE_CYGWIN
1084                 umask(prev_mask);
1085 #endif
1086                 cleanup_exit(1);
1087         }
1088 #ifdef HAVE_CYGWIN
1089         umask(prev_mask);
1090 #endif
1091         if (listen(sock, 5) < 0) {
1092                 perror("listen");
1093                 cleanup_exit(1);
1094         }
1095
1096         /*
1097          * Fork, and have the parent execute the command, if any, or present
1098          * the socket data.  The child continues as the authentication agent.
1099          */
1100         if (d_flag) {
1101                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1102                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1103                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1104                     SSH_AUTHSOCKET_ENV_NAME);
1105                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1106                 goto skip;
1107         }
1108         pid = fork();
1109         if (pid == -1) {
1110                 perror("fork");
1111                 cleanup_exit(1);
1112         }
1113         if (pid != 0) {         /* Parent - execute the given command. */
1114                 close(sock);
1115                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1116                 if (ac == 0) {
1117                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1118                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1119                             SSH_AUTHSOCKET_ENV_NAME);
1120                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1121                             SSH_AGENTPID_ENV_NAME);
1122                         printf("echo Agent pid %ld;\n", (long)pid);
1123                         exit(0);
1124                 }
1125                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1126                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1127                         perror("setenv");
1128                         exit(1);
1129                 }
1130                 execvp(av[0], av);
1131                 perror(av[0]);
1132                 exit(1);
1133         }
1134         /* child */
1135         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1136
1137         if (setsid() == -1) {
1138                 error("setsid: %s", strerror(errno));
1139                 cleanup_exit(1);
1140         }
1141
1142         (void)chdir("/");
1143         close(0);
1144         close(1);
1145         close(2);
1146
1147 #ifdef HAVE_SETRLIMIT
1148         /* deny core dumps, since memory contains unencrypted private keys */
1149         rlim.rlim_cur = rlim.rlim_max = 0;
1150         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1151                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1152                 cleanup_exit(1);
1153         }
1154 #endif
1155
1156 skip:
1157         fatal_add_cleanup(cleanup_socket, NULL);
1158         new_socket(AUTH_SOCKET, sock);
1159         if (ac > 0) {
1160                 signal(SIGALRM, check_parent_exists);
1161                 alarm(10);
1162         }
1163         idtab_init();
1164         if (!d_flag)
1165                 signal(SIGINT, SIG_IGN);
1166         signal(SIGPIPE, SIG_IGN);
1167         signal(SIGHUP, cleanup_handler);
1168         signal(SIGTERM, cleanup_handler);
1169         nalloc = 0;
1170
1171         while (1) {
1172                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1173                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1174                         if (errno == EINTR)
1175                                 continue;
1176                         fatal("select: %s", strerror(errno));
1177                 }
1178                 after_select(readsetp, writesetp);
1179         }
1180         /* NOTREACHED */
1181 }