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 1.95 2002/06/19 00:27:55 deraadt 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 }
 369
 370 static void
 371 reaper(void)
 372 {
 373         Idtab *tab;
 374         Identity *id, *nxt;
 375         int version;
 376         u_int now = time(NULL);
 377
 378         for (version = 1; version < 3; version++) {
 379                 tab = idtab_lookup(version);
 380                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 381                         nxt = TAILQ_NEXT(id, next);
 382                         if (id->death != 0 && now >= id->death) {
 383                                 TAILQ_REMOVE(&tab->idlist, id, next);
 384                                 free_identity(id);
 385                                 tab->nentries--;
 386                         }
 387                 }
 388         }
 389 }
 390
 391 static void
 392 process_add_identity(SocketEntry *e, int version)
 393 {
 394         Key *k = NULL;
 395         char *type_name;
 396         char *comment;
 397         int type, success = 0, death = 0;
 398         Idtab *tab = idtab_lookup(version);
 399
 400         switch (version) {
 401         case 1:
 402                 k = key_new_private(KEY_RSA1);
 403                 buffer_get_int(&e->request);                    /* ignored */
 404                 buffer_get_bignum(&e->request, k->rsa->n);
 405                 buffer_get_bignum(&e->request, k->rsa->e);
 406                 buffer_get_bignum(&e->request, k->rsa->d);
 407                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 408
 409                 /* SSH and SSL have p and q swapped */
 410                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 411                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 412
 413                 /* Generate additional parameters */
 414                 rsa_generate_additional_parameters(k->rsa);
 415                 break;
 416         case 2:
 417                 type_name = buffer_get_string(&e->request, NULL);
 418                 type = key_type_from_name(type_name);
 419                 xfree(type_name);
 420                 switch (type) {
 421                 case KEY_DSA:
 422                         k = key_new_private(type);
 423                         buffer_get_bignum2(&e->request, k->dsa->p);
 424                         buffer_get_bignum2(&e->request, k->dsa->q);
 425                         buffer_get_bignum2(&e->request, k->dsa->g);
 426                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 427                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 428                         break;
 429                 case KEY_RSA:
 430                         k = key_new_private(type);
 431                         buffer_get_bignum2(&e->request, k->rsa->n);
 432                         buffer_get_bignum2(&e->request, k->rsa->e);
 433                         buffer_get_bignum2(&e->request, k->rsa->d);
 434                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 435                         buffer_get_bignum2(&e->request, k->rsa->p);
 436                         buffer_get_bignum2(&e->request, k->rsa->q);
 437
 438                         /* Generate additional parameters */
 439                         rsa_generate_additional_parameters(k->rsa);
 440                         break;
 441                 default:
 442                         buffer_clear(&e->request);
 443                         goto send;
 444                 }
 445                 break;
 446         }
 447         comment = buffer_get_string(&e->request, NULL);
 448         if (k == NULL) {
 449                 xfree(comment);
 450                 goto send;
 451         }
 452         success = 1;
 453         while (buffer_len(&e->request)) {
 454                 switch (buffer_get_char(&e->request)) {
 455                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 456                         death = time(NULL) + buffer_get_int(&e->request);
 457                         break;
 458                 default:
 459                         break;
 460                 }
 461         }
 462         if (lookup_identity(k, version) == NULL) {
 463                 Identity *id = xmalloc(sizeof(Identity));
 464                 id->key = k;
 465                 id->comment = comment;
 466                 id->death = death;
 467                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 468                 /* Increment the number of identities. */
 469                 tab->nentries++;
 470         } else {
 471                 key_free(k);
 472                 xfree(comment);
 473         }
 474 send:
 475         buffer_put_int(&e->output, 1);
 476         buffer_put_char(&e->output,
 477             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 478 }
 479
 480 /* XXX todo: encrypt sensitive data with passphrase */
 481 static void
 482 process_lock_agent(SocketEntry *e, int lock)
 483 {
 484         char *passwd;
 485         int success = 0;
 486
 487         passwd = buffer_get_string(&e->request, NULL);
 488         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 489                 locked = 0;
 490                 memset(lock_passwd, 0, strlen(lock_passwd));
 491                 xfree(lock_passwd);
 492                 lock_passwd = NULL;
 493                 success = 1;
 494         } else if (!locked && lock) {
 495                 locked = 1;
 496                 lock_passwd = xstrdup(passwd);
 497                 success = 1;
 498         }
 499         memset(passwd, 0, strlen(passwd));
 500         xfree(passwd);
 501
 502         buffer_put_int(&e->output, 1);
 503         buffer_put_char(&e->output,
 504             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 505 }
 506
 507 static void
 508 no_identities(SocketEntry *e, u_int type)
 509 {
 510         Buffer msg;
 511
 512         buffer_init(&msg);
 513         buffer_put_char(&msg,
 514             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 515             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 516         buffer_put_int(&msg, 0);
 517         buffer_put_int(&e->output, buffer_len(&msg));
 518         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 519         buffer_free(&msg);
 520 }
 521
 522 #ifdef SMARTCARD
 523 static void
 524 process_add_smartcard_key (SocketEntry *e)
 525 {
 526         Identity *id;
 527         Idtab *tab;
 528         Key **keys, *k;
 529         char *sc_reader_id = NULL, *pin;
 530         int i, version, success = 0;
 531
 532         sc_reader_id = buffer_get_string(&e->request, NULL);
 533         pin = buffer_get_string(&e->request, NULL);
 534         keys = sc_get_keys(sc_reader_id, pin);
 535         xfree(sc_reader_id);
 536         xfree(pin);
 537
 538         if (keys == NULL || keys[0] == NULL) {
 539                 error("sc_get_keys failed");
 540                 goto send;
 541         }
 542         for (i = 0; keys[i] != NULL; i++) {
 543                 k = keys[i];
 544                 version = k->type == KEY_RSA1 ? 1 : 2;
 545                 tab = idtab_lookup(version);
 546                 if (lookup_identity(k, version) == NULL) {
 547                         id = xmalloc(sizeof(Identity));
 548                         id->key = k;
 549                         id->comment = xstrdup("smartcard key");
 550                         id->death = 0;
 551                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 552                         tab->nentries++;
 553                         success = 1;
 554                 } else {
 555                         key_free(k);
 556                 }
 557                 keys[i] = NULL;
 558         }
 559         xfree(keys);
 560 send:
 561         buffer_put_int(&e->output, 1);
 562         buffer_put_char(&e->output,
 563             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 564 }
 565
 566 static void
 567 process_remove_smartcard_key(SocketEntry *e)
 568 {
 569         Identity *id;
 570         Idtab *tab;
 571         Key **keys, *k = NULL;
 572         char *sc_reader_id = NULL, *pin;
 573         int i, version, success = 0;
 574
 575         sc_reader_id = buffer_get_string(&e->request, NULL);
 576         pin = buffer_get_string(&e->request, NULL);
 577         keys = sc_get_keys(sc_reader_id, pin);
 578         xfree(sc_reader_id);
 579         xfree(pin);
 580
 581         if (keys == NULL || keys[0] == NULL) {
 582                 error("sc_get_keys failed");
 583                 goto send;
 584         }
 585         for (i = 0; keys[i] != NULL; i++) {
 586                 k = keys[i];
 587                 version = k->type == KEY_RSA1 ? 1 : 2;
 588                 if ((id = lookup_identity(k, version)) != NULL) {
 589                         tab = idtab_lookup(version);
 590                         TAILQ_REMOVE(&tab->idlist, id, next);
 591                         tab->nentries--;
 592                         free_identity(id);
 593                         success = 1;
 594                 }
 595                 key_free(k);
 596                 keys[i] = NULL;
 597         }
 598         xfree(keys);
 599 send:
 600         buffer_put_int(&e->output, 1);
 601         buffer_put_char(&e->output,
 602             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 603 }
 604 #endif /* SMARTCARD */
 605
 606 /* dispatch incoming messages */
 607
 608 static void
 609 process_message(SocketEntry *e)
 610 {
 611         u_int msg_len;
 612         u_int type;
 613         u_char *cp;
 614
 615         /* kill dead keys */
 616         reaper();
 617
 618         if (buffer_len(&e->input) < 5)
 619                 return;         /* Incomplete message. */
 620         cp = buffer_ptr(&e->input);
 621         msg_len = GET_32BIT(cp);
 622         if (msg_len > 256 * 1024) {
 623                 shutdown(e->fd, SHUT_RDWR);
 624                 close(e->fd);
 625                 e->type = AUTH_UNUSED;
 626                 buffer_free(&e->input);
 627                 buffer_free(&e->output);
 628                 buffer_free(&e->request);
 629                 return;
 630         }
 631         if (buffer_len(&e->input) < msg_len + 4)
 632                 return;
 633
 634         /* move the current input to e->request */
 635         buffer_consume(&e->input, 4);
 636         buffer_clear(&e->request);
 637         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 638         buffer_consume(&e->input, msg_len);
 639         type = buffer_get_char(&e->request);
 640
 641         /* check wheter agent is locked */
 642         if (locked && type != SSH_AGENTC_UNLOCK) {
 643                 buffer_clear(&e->request);
 644                 switch (type) {
 645                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 646                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 647                         /* send empty lists */
 648                         no_identities(e, type);
 649                         break;
 650                 default:
 651                         /* send a fail message for all other request types */
 652                         buffer_put_int(&e->output, 1);
 653                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 654                 }
 655                 return;
 656         }
 657
 658         debug("type %d", type);
 659         switch (type) {
 660         case SSH_AGENTC_LOCK:
 661         case SSH_AGENTC_UNLOCK:
 662                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 663                 break;
 664         /* ssh1 */
 665         case SSH_AGENTC_RSA_CHALLENGE:
 666                 process_authentication_challenge1(e);
 667                 break;
 668         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 669                 process_request_identities(e, 1);
 670                 break;
 671         case SSH_AGENTC_ADD_RSA_IDENTITY:
 672         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 673                 process_add_identity(e, 1);
 674                 break;
 675         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 676                 process_remove_identity(e, 1);
 677                 break;
 678         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 679                 process_remove_all_identities(e, 1);
 680                 break;
 681         /* ssh2 */
 682         case SSH2_AGENTC_SIGN_REQUEST:
 683                 process_sign_request2(e);
 684                 break;
 685         case SSH2_AGENTC_REQUEST_IDENTITIES:
 686                 process_request_identities(e, 2);
 687                 break;
 688         case SSH2_AGENTC_ADD_IDENTITY:
 689         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 690                 process_add_identity(e, 2);
 691                 break;
 692         case SSH2_AGENTC_REMOVE_IDENTITY:
 693                 process_remove_identity(e, 2);
 694                 break;
 695         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 696                 process_remove_all_identities(e, 2);
 697                 break;
 698 #ifdef SMARTCARD
 699         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 700                 process_add_smartcard_key(e);
 701                 break;
 702         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 703                 process_remove_smartcard_key(e);
 704                 break;
 705 #endif /* SMARTCARD */
 706         default:
 707                 /* Unknown message.  Respond with failure. */
 708                 error("Unknown message %d", type);
 709                 buffer_clear(&e->request);
 710                 buffer_put_int(&e->output, 1);
 711                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 712                 break;
 713         }
 714 }
 715
 716 static void
 717 new_socket(sock_type type, int fd)
 718 {
 719         u_int i, old_alloc;
 720         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 721                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 722
 723         if (fd > max_fd)
 724                 max_fd = fd;
 725
 726         for (i = 0; i < sockets_alloc; i++)
 727                 if (sockets[i].type == AUTH_UNUSED) {
 728                         sockets[i].fd = fd;
 729                         sockets[i].type = type;
 730                         buffer_init(&sockets[i].input);
 731                         buffer_init(&sockets[i].output);
 732                         buffer_init(&sockets[i].request);
 733                         return;
 734                 }
 735         old_alloc = sockets_alloc;
 736         sockets_alloc += 10;
 737         if (sockets)
 738                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 739         else
 740                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 741         for (i = old_alloc; i < sockets_alloc; i++)
 742                 sockets[i].type = AUTH_UNUSED;
 743         sockets[old_alloc].type = type;
 744         sockets[old_alloc].fd = fd;
 745         buffer_init(&sockets[old_alloc].input);
 746         buffer_init(&sockets[old_alloc].output);
 747         buffer_init(&sockets[old_alloc].request);
 748 }
 749
 750 static int
 751 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 752 {
 753         u_int i, sz;
 754         int n = 0;
 755
 756         for (i = 0; i < sockets_alloc; i++) {
 757                 switch (sockets[i].type) {
 758                 case AUTH_SOCKET:
 759                 case AUTH_CONNECTION:
 760                         n = MAX(n, sockets[i].fd);
 761                         break;
 762                 case AUTH_UNUSED:
 763                         break;
 764                 default:
 765                         fatal("Unknown socket type %d", sockets[i].type);
 766                         break;
 767                 }
 768         }
 769
 770         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 771         if (*fdrp == NULL || sz > *nallocp) {
 772                 if (*fdrp)
 773                         xfree(*fdrp);
 774                 if (*fdwp)
 775                         xfree(*fdwp);
 776                 *fdrp = xmalloc(sz);
 777                 *fdwp = xmalloc(sz);
 778                 *nallocp = sz;
 779         }
 780         if (n < *fdl)
 781                 debug("XXX shrink: %d < %d", n, *fdl);
 782         *fdl = n;
 783         memset(*fdrp, 0, sz);
 784         memset(*fdwp, 0, sz);
 785
 786         for (i = 0; i < sockets_alloc; i++) {
 787                 switch (sockets[i].type) {
 788                 case AUTH_SOCKET:
 789                 case AUTH_CONNECTION:
 790                         FD_SET(sockets[i].fd, *fdrp);
 791                         if (buffer_len(&sockets[i].output) > 0)
 792                                 FD_SET(sockets[i].fd, *fdwp);
 793                         break;
 794                 default:
 795                         break;
 796                 }
 797         }
 798         return (1);
 799 }
 800
 801 static void
 802 after_select(fd_set *readset, fd_set *writeset)
 803 {
 804         u_int i;
 805         int len, sock;
 806         socklen_t slen;
 807         char buf[1024];
 808         struct sockaddr_un sunaddr;
 809
 810         for (i = 0; i < sockets_alloc; i++)
 811                 switch (sockets[i].type) {
 812                 case AUTH_UNUSED:
 813                         break;
 814                 case AUTH_SOCKET:
 815                         if (FD_ISSET(sockets[i].fd, readset)) {
 816                                 slen = sizeof(sunaddr);
 817                                 sock = accept(sockets[i].fd,
 818                                     (struct sockaddr *) &sunaddr, &slen);
 819                                 if (sock < 0) {
 820                                         error("accept from AUTH_SOCKET: %s",
 821                                             strerror(errno));
 822                                         break;
 823                                 }
 824                                 new_socket(AUTH_CONNECTION, sock);
 825                         }
 826                         break;
 827                 case AUTH_CONNECTION:
 828                         if (buffer_len(&sockets[i].output) > 0 &&
 829                             FD_ISSET(sockets[i].fd, writeset)) {
 830                                 do {
 831                                         len = write(sockets[i].fd,
 832                                             buffer_ptr(&sockets[i].output),
 833                                             buffer_len(&sockets[i].output));
 834                                         if (len == -1 && (errno == EAGAIN ||
 835                                             errno == EINTR))
 836                                                 continue;
 837                                         break;
 838                                 } while (1);
 839                                 if (len <= 0) {
 840                                         shutdown(sockets[i].fd, SHUT_RDWR);
 841                                         close(sockets[i].fd);
 842                                         sockets[i].type = AUTH_UNUSED;
 843                                         buffer_free(&sockets[i].input);
 844                                         buffer_free(&sockets[i].output);
 845                                         buffer_free(&sockets[i].request);
 846                                         break;
 847                                 }
 848                                 buffer_consume(&sockets[i].output, len);
 849                         }
 850                         if (FD_ISSET(sockets[i].fd, readset)) {
 851                                 do {
 852                                         len = read(sockets[i].fd, buf, sizeof(buf));
 853                                         if (len == -1 && (errno == EAGAIN ||
 854                                             errno == EINTR))
 855                                                 continue;
 856                                         break;
 857                                 } while (1);
 858                                 if (len <= 0) {
 859                                         shutdown(sockets[i].fd, SHUT_RDWR);
 860                                         close(sockets[i].fd);
 861                                         sockets[i].type = AUTH_UNUSED;
 862                                         buffer_free(&sockets[i].input);
 863                                         buffer_free(&sockets[i].output);
 864                                         buffer_free(&sockets[i].request);
 865                                         break;
 866                                 }
 867                                 buffer_append(&sockets[i].input, buf, len);
 868                                 process_message(&sockets[i]);
 869                         }
 870                         break;
 871                 default:
 872                         fatal("Unknown type %d", sockets[i].type);
 873                 }
 874 }
 875
 876 static void
 877 cleanup_socket(void *p)
 878 {
 879         if (socket_name[0])
 880                 unlink(socket_name);
 881         if (socket_dir[0])
 882                 rmdir(socket_dir);
 883 }
 884
 885 static void
 886 cleanup_exit(int i)
 887 {
 888         cleanup_socket(NULL);
 889         exit(i);
 890 }
 891
 892 static void
 893 cleanup_handler(int sig)
 894 {
 895         cleanup_socket(NULL);
 896         _exit(2);
 897 }
 898
 899 static void
 900 check_parent_exists(int sig)
 901 {
 902         int save_errno = errno;
 903
 904         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 905                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 906                 cleanup_handler(sig); /* safe */
 907         }
 908         signal(SIGALRM, check_parent_exists);
 909         alarm(10);
 910         errno = save_errno;
 911 }
 912
 913 static void
 914 usage(void)
 915 {
 916         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 917             __progname);
 918         fprintf(stderr, "Options:\n");
 919         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 920         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 921         fprintf(stderr, "  -k          Kill the current agent.\n");
 922         fprintf(stderr, "  -d          Debug mode.\n");
 923         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 924         exit(1);
 925 }
 926
 927 int
 928 main(int ac, char **av)
 929 {
 930         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 931         struct sockaddr_un sunaddr;
 932 #ifdef HAVE_SETRLIMIT
 933         struct rlimit rlim;
 934 #endif
 935 #ifdef HAVE_CYGWIN
 936         int prev_mask;
 937 #endif
 938         pid_t pid;
 939         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 940         char *agentsocket = NULL;
 941         extern int optind;
 942         fd_set *readsetp = NULL, *writesetp = NULL;
 943
 944         SSLeay_add_all_algorithms();
 945
 946         __progname = get_progname(av[0]);
 947         init_rng();
 948         seed_rng();
 949
 950         while ((ch = getopt(ac, av, "cdksa:")) != -1) {
 951                 switch (ch) {
 952                 case 'c':
 953                         if (s_flag)
 954                                 usage();
 955                         c_flag++;
 956                         break;
 957                 case 'k':
 958                         k_flag++;
 959                         break;
 960                 case 's':
 961                         if (c_flag)
 962                                 usage();
 963                         s_flag++;
 964                         break;
 965                 case 'd':
 966                         if (d_flag)
 967                                 usage();
 968                         d_flag++;
 969                         break;
 970                 case 'a':
 971                         agentsocket = optarg;
 972                         break;
 973                 default:
 974                         usage();
 975                 }
 976         }
 977         ac -= optind;
 978         av += optind;
 979
 980         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
 981                 usage();
 982
 983         if (ac == 0 && !c_flag && !s_flag) {
 984                 shell = getenv("SHELL");
 985                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 986                         c_flag = 1;
 987         }
 988         if (k_flag) {
 989                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 990                 if (pidstr == NULL) {
 991                         fprintf(stderr, "%s not set, cannot kill agent\n",
 992                             SSH_AGENTPID_ENV_NAME);
 993                         exit(1);
 994                 }
 995                 pid = atoi(pidstr);
 996                 if (pid < 1) {
 997                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 998                             SSH_AGENTPID_ENV_NAME, pidstr);
 999                         exit(1);
1000                 }
1001                 if (kill(pid, SIGTERM) == -1) {
1002                         perror("kill");
1003                         exit(1);
1004                 }
1005                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1006                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1007                 printf(format, SSH_AGENTPID_ENV_NAME);
1008                 printf("echo Agent pid %ld killed;\n", (long)pid);
1009                 exit(0);
1010         }
1011         parent_pid = getpid();
1012
1013         if (agentsocket == NULL) {
1014                 /* Create private directory for agent socket */
1015                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
1016                 if (mkdtemp(socket_dir) == NULL) {
1017                         perror("mkdtemp: private socket dir");
1018                         exit(1);
1019                 }
1020                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1021                     (long)parent_pid);
1022         } else {
1023                 /* Try to use specified agent socket */
1024                 socket_dir[0] = '\0';
1025                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1026         }
1027
1028         /*
1029          * Create socket early so it will exist before command gets run from
1030          * the parent.
1031          */
1032         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1033         if (sock < 0) {
1034                 perror("socket");
1035                 cleanup_exit(1);
1036         }
1037         memset(&sunaddr, 0, sizeof(sunaddr));
1038         sunaddr.sun_family = AF_UNIX;
1039         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1040 #ifdef HAVE_CYGWIN
1041         prev_mask = umask(0177);
1042 #endif
1043         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1044                 perror("bind");
1045 #ifdef HAVE_CYGWIN
1046                 umask(prev_mask);
1047 #endif
1048                 cleanup_exit(1);
1049         }
1050 #ifdef HAVE_CYGWIN
1051         umask(prev_mask);
1052 #endif
1053         if (listen(sock, 5) < 0) {
1054                 perror("listen");
1055                 cleanup_exit(1);
1056         }
1057
1058         /*
1059          * Fork, and have the parent execute the command, if any, or present
1060          * the socket data.  The child continues as the authentication agent.
1061          */
1062         if (d_flag) {
1063                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1064                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1065                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1066                     SSH_AUTHSOCKET_ENV_NAME);
1067                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1068                 goto skip;
1069         }
1070         pid = fork();
1071         if (pid == -1) {
1072                 perror("fork");
1073                 cleanup_exit(1);
1074         }
1075         if (pid != 0) {         /* Parent - execute the given command. */
1076                 close(sock);
1077                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1078                 if (ac == 0) {
1079                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1080                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1081                             SSH_AUTHSOCKET_ENV_NAME);
1082                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1083                             SSH_AGENTPID_ENV_NAME);
1084                         printf("echo Agent pid %ld;\n", (long)pid);
1085                         exit(0);
1086                 }
1087                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1088                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1089                         perror("setenv");
1090                         exit(1);
1091                 }
1092                 execvp(av[0], av);
1093                 perror(av[0]);
1094                 exit(1);
1095         }
1096         /* child */
1097         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1098
1099         if (setsid() == -1) {
1100                 error("setsid: %s", strerror(errno));
1101                 cleanup_exit(1);
1102         }
1103
1104         (void)chdir("/");
1105         close(0);
1106         close(1);
1107         close(2);
1108
1109 #ifdef HAVE_SETRLIMIT
1110         /* deny core dumps, since memory contains unencrypted private keys */
1111         rlim.rlim_cur = rlim.rlim_max = 0;
1112         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1113                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1114                 cleanup_exit(1);
1115         }
1116 #endif
1117
1118 skip:
1119         fatal_add_cleanup(cleanup_socket, NULL);
1120         new_socket(AUTH_SOCKET, sock);
1121         if (ac > 0) {
1122                 signal(SIGALRM, check_parent_exists);
1123                 alarm(10);
1124         }
1125         idtab_init();
1126         if (!d_flag)
1127                 signal(SIGINT, SIG_IGN);
1128         signal(SIGPIPE, SIG_IGN);
1129         signal(SIGHUP, cleanup_handler);
1130         signal(SIGTERM, cleanup_handler);
1131         nalloc = 0;
1132
1133         while (1) {
1134                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1135                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1136                         if (errno == EINTR)
1137                                 continue;
1138                         fatal("select: %s", strerror(errno));
1139                 }
1140                 after_select(readsetp, writesetp);
1141         }
1142         /* NOTREACHED */
1143 }