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 1.96 2002/06/23 10:29:52 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
 114         for (i = 0; i <=2; i++) {
 115                 TAILQ_INIT(&idtable[i].idlist);
 116                 idtable[i].nentries = 0;
 117         }
 118 }
 119
 120 /* return private key table for requested protocol version */
 121 static Idtab *
 122 idtab_lookup(int version)
 123 {
 124         if (version < 1 || version > 2)
 125                 fatal("internal error, bad protocol version %d", version);
 126         return &idtable[version];
 127 }
 128
 129 static void
 130 free_identity(Identity *id)
 131 {
 132         key_free(id->key);
 133         xfree(id->comment);
 134         xfree(id);
 135 }
 136
 137 /* return matching private key for given public key */
 138 static Identity *
 139 lookup_identity(Key *key, int version)
 140 {
 141         Identity *id;
 142
 143         Idtab *tab = idtab_lookup(version);
 144         TAILQ_FOREACH(id, &tab->idlist, next) {
 145                 if (key_equal(key, id->key))
 146                         return (id);
 147         }
 148         return (NULL);
 149 }
 150
 151 /* send list of supported public keys to 'client' */
 152 static void
 153 process_request_identities(SocketEntry *e, int version)
 154 {
 155         Idtab *tab = idtab_lookup(version);
 156         Identity *id;
 157         Buffer msg;
 158
 159         buffer_init(&msg);
 160         buffer_put_char(&msg, (version == 1) ?
 161             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 162         buffer_put_int(&msg, tab->nentries);
 163         TAILQ_FOREACH(id, &tab->idlist, next) {
 164                 if (id->key->type == KEY_RSA1) {
 165                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 166                         buffer_put_bignum(&msg, id->key->rsa->e);
 167                         buffer_put_bignum(&msg, id->key->rsa->n);
 168                 } else {
 169                         u_char *blob;
 170                         u_int blen;
 171                         key_to_blob(id->key, &blob, &blen);
 172                         buffer_put_string(&msg, blob, blen);
 173                         xfree(blob);
 174                 }
 175                 buffer_put_cstring(&msg, id->comment);
 176         }
 177         buffer_put_int(&e->output, buffer_len(&msg));
 178         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 179         buffer_free(&msg);
 180 }
 181
 182 /* ssh1 only */
 183 static void
 184 process_authentication_challenge1(SocketEntry *e)
 185 {
 186         u_char buf[32], mdbuf[16], session_id[16];
 187         u_int response_type;
 188         BIGNUM *challenge;
 189         Identity *id;
 190         int i, len;
 191         Buffer msg;
 192         MD5_CTX md;
 193         Key *key;
 194
 195         buffer_init(&msg);
 196         key = key_new(KEY_RSA1);
 197         if ((challenge = BN_new()) == NULL)
 198                 fatal("process_authentication_challenge1: BN_new failed");
 199
 200         buffer_get_int(&e->request);                            /* ignored */
 201         buffer_get_bignum(&e->request, key->rsa->e);
 202         buffer_get_bignum(&e->request, key->rsa->n);
 203         buffer_get_bignum(&e->request, challenge);
 204
 205         /* Only protocol 1.1 is supported */
 206         if (buffer_len(&e->request) == 0)
 207                 goto failure;
 208         buffer_get(&e->request, session_id, 16);
 209         response_type = buffer_get_int(&e->request);
 210         if (response_type != 1)
 211                 goto failure;
 212
 213         id = lookup_identity(key, 1);
 214         if (id != NULL) {
 215                 Key *private = id->key;
 216                 /* Decrypt the challenge using the private key. */
 217                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 218                         goto failure;
 219
 220                 /* The response is MD5 of decrypted challenge plus session id. */
 221                 len = BN_num_bytes(challenge);
 222                 if (len <= 0 || len > 32) {
 223                         log("process_authentication_challenge: bad challenge length %d", len);
 224                         goto failure;
 225                 }
 226                 memset(buf, 0, 32);
 227                 BN_bn2bin(challenge, buf + 32 - len);
 228                 MD5_Init(&md);
 229                 MD5_Update(&md, buf, 32);
 230                 MD5_Update(&md, session_id, 16);
 231                 MD5_Final(mdbuf, &md);
 232
 233                 /* Send the response. */
 234                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 235                 for (i = 0; i < 16; i++)
 236                         buffer_put_char(&msg, mdbuf[i]);
 237                 goto send;
 238         }
 239
 240 failure:
 241         /* Unknown identity or protocol error.  Send failure. */
 242         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 243 send:
 244         buffer_put_int(&e->output, buffer_len(&msg));
 245         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 246         key_free(key);
 247         BN_clear_free(challenge);
 248         buffer_free(&msg);
 249 }
 250
 251 /* ssh2 only */
 252 static void
 253 process_sign_request2(SocketEntry *e)
 254 {
 255         u_char *blob, *data, *signature = NULL;
 256         u_int blen, dlen, slen = 0;
 257         extern int datafellows;
 258         int ok = -1, flags;
 259         Buffer msg;
 260         Key *key;
 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         u_int blen, bits;
 300         int success = 0;
 301         Key *key = NULL;
 302         u_char *blob;
 303
 304         switch (version) {
 305         case 1:
 306                 key = key_new(KEY_RSA1);
 307                 bits = buffer_get_int(&e->request);
 308                 buffer_get_bignum(&e->request, key->rsa->e);
 309                 buffer_get_bignum(&e->request, key->rsa->n);
 310
 311                 if (bits != key_size(key))
 312                         log("Warning: identity keysize mismatch: actual %u, announced %u",
 313                             key_size(key), bits);
 314                 break;
 315         case 2:
 316                 blob = buffer_get_string(&e->request, &blen);
 317                 key = key_from_blob(blob, blen);
 318                 xfree(blob);
 319                 break;
 320         }
 321         if (key != NULL) {
 322                 Identity *id = lookup_identity(key, version);
 323                 if (id != NULL) {
 324                         /*
 325                          * We have this key.  Free the old key.  Since we
 326                          * don\'t want to leave empty slots in the middle of
 327                          * the array, we actually free the key there and move
 328                          * all the entries between the empty slot and the end
 329                          * of the array.
 330                          */
 331                         Idtab *tab = idtab_lookup(version);
 332                         if (tab->nentries < 1)
 333                                 fatal("process_remove_identity: "
 334                                     "internal error: tab->nentries %d",
 335                                     tab->nentries);
 336                         TAILQ_REMOVE(&tab->idlist, id, next);
 337                         free_identity(id);
 338                         tab->nentries--;
 339                         success = 1;
 340                 }
 341                 key_free(key);
 342         }
 343         buffer_put_int(&e->output, 1);
 344         buffer_put_char(&e->output,
 345             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 346 }
 347
 348 static void
 349 process_remove_all_identities(SocketEntry *e, int version)
 350 {
 351         Idtab *tab = idtab_lookup(version);
 352         Identity *id;
 353
 354         /* Loop over all identities and clear the keys. */
 355         for (id = TAILQ_FIRST(&tab->idlist); id;
 356             id = TAILQ_FIRST(&tab->idlist)) {
 357                 TAILQ_REMOVE(&tab->idlist, id, next);
 358                 free_identity(id);
 359         }
 360
 361         /* Mark that there are no identities. */
 362         tab->nentries = 0;
 363
 364         /* Send success. */
 365         buffer_put_int(&e->output, 1);
 366         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 367 }
 368
 369 static void
 370 reaper(void)
 371 {
 372         u_int now = time(NULL);
 373         Identity *id, *nxt;
 374         int version;
 375         Idtab *tab;
 376
 377         for (version = 1; version < 3; version++) {
 378                 tab = idtab_lookup(version);
 379                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 380                         nxt = TAILQ_NEXT(id, next);
 381                         if (id->death != 0 && now >= id->death) {
 382                                 TAILQ_REMOVE(&tab->idlist, id, next);
 383                                 free_identity(id);
 384                                 tab->nentries--;
 385                         }
 386                 }
 387         }
 388 }
 389
 390 static void
 391 process_add_identity(SocketEntry *e, int version)
 392 {
 393         Idtab *tab = idtab_lookup(version);
 394         int type, success = 0, death = 0;
 395         char *type_name, *comment;
 396         Key *k = NULL;
 397
 398         switch (version) {
 399         case 1:
 400                 k = key_new_private(KEY_RSA1);
 401                 buffer_get_int(&e->request);                    /* ignored */
 402                 buffer_get_bignum(&e->request, k->rsa->n);
 403                 buffer_get_bignum(&e->request, k->rsa->e);
 404                 buffer_get_bignum(&e->request, k->rsa->d);
 405                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 406
 407                 /* SSH and SSL have p and q swapped */
 408                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 409                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 410
 411                 /* Generate additional parameters */
 412                 rsa_generate_additional_parameters(k->rsa);
 413                 break;
 414         case 2:
 415                 type_name = buffer_get_string(&e->request, NULL);
 416                 type = key_type_from_name(type_name);
 417                 xfree(type_name);
 418                 switch (type) {
 419                 case KEY_DSA:
 420                         k = key_new_private(type);
 421                         buffer_get_bignum2(&e->request, k->dsa->p);
 422                         buffer_get_bignum2(&e->request, k->dsa->q);
 423                         buffer_get_bignum2(&e->request, k->dsa->g);
 424                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 425                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 426                         break;
 427                 case KEY_RSA:
 428                         k = key_new_private(type);
 429                         buffer_get_bignum2(&e->request, k->rsa->n);
 430                         buffer_get_bignum2(&e->request, k->rsa->e);
 431                         buffer_get_bignum2(&e->request, k->rsa->d);
 432                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 433                         buffer_get_bignum2(&e->request, k->rsa->p);
 434                         buffer_get_bignum2(&e->request, k->rsa->q);
 435
 436                         /* Generate additional parameters */
 437                         rsa_generate_additional_parameters(k->rsa);
 438                         break;
 439                 default:
 440                         buffer_clear(&e->request);
 441                         goto send;
 442                 }
 443                 break;
 444         }
 445         comment = buffer_get_string(&e->request, NULL);
 446         if (k == NULL) {
 447                 xfree(comment);
 448                 goto send;
 449         }
 450         success = 1;
 451         while (buffer_len(&e->request)) {
 452                 switch (buffer_get_char(&e->request)) {
 453                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 454                         death = time(NULL) + buffer_get_int(&e->request);
 455                         break;
 456                 default:
 457                         break;
 458                 }
 459         }
 460         if (lookup_identity(k, version) == NULL) {
 461                 Identity *id = xmalloc(sizeof(Identity));
 462                 id->key = k;
 463                 id->comment = comment;
 464                 id->death = death;
 465                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 466                 /* Increment the number of identities. */
 467                 tab->nentries++;
 468         } else {
 469                 key_free(k);
 470                 xfree(comment);
 471         }
 472 send:
 473         buffer_put_int(&e->output, 1);
 474         buffer_put_char(&e->output,
 475             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 476 }
 477
 478 /* XXX todo: encrypt sensitive data with passphrase */
 479 static void
 480 process_lock_agent(SocketEntry *e, int lock)
 481 {
 482         int success = 0;
 483         char *passwd;
 484
 485         passwd = buffer_get_string(&e->request, NULL);
 486         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 487                 locked = 0;
 488                 memset(lock_passwd, 0, strlen(lock_passwd));
 489                 xfree(lock_passwd);
 490                 lock_passwd = NULL;
 491                 success = 1;
 492         } else if (!locked && lock) {
 493                 locked = 1;
 494                 lock_passwd = xstrdup(passwd);
 495                 success = 1;
 496         }
 497         memset(passwd, 0, strlen(passwd));
 498         xfree(passwd);
 499
 500         buffer_put_int(&e->output, 1);
 501         buffer_put_char(&e->output,
 502             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 503 }
 504
 505 static void
 506 no_identities(SocketEntry *e, u_int type)
 507 {
 508         Buffer msg;
 509
 510         buffer_init(&msg);
 511         buffer_put_char(&msg,
 512             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 513             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 514         buffer_put_int(&msg, 0);
 515         buffer_put_int(&e->output, buffer_len(&msg));
 516         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 517         buffer_free(&msg);
 518 }
 519
 520 #ifdef SMARTCARD
 521 static void
 522 process_add_smartcard_key (SocketEntry *e)
 523 {
 524         char *sc_reader_id = NULL, *pin;
 525         int i, version, success = 0;
 526         Key **keys, *k;
 527         Identity *id;
 528         Idtab *tab;
 529
 530         sc_reader_id = buffer_get_string(&e->request, NULL);
 531         pin = buffer_get_string(&e->request, NULL);
 532         keys = sc_get_keys(sc_reader_id, pin);
 533         xfree(sc_reader_id);
 534         xfree(pin);
 535
 536         if (keys == NULL || keys[0] == NULL) {
 537                 error("sc_get_keys failed");
 538                 goto send;
 539         }
 540         for (i = 0; keys[i] != NULL; i++) {
 541                 k = keys[i];
 542                 version = k->type == KEY_RSA1 ? 1 : 2;
 543                 tab = idtab_lookup(version);
 544                 if (lookup_identity(k, version) == NULL) {
 545                         id = xmalloc(sizeof(Identity));
 546                         id->key = k;
 547                         id->comment = xstrdup("smartcard key");
 548                         id->death = 0;
 549                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 550                         tab->nentries++;
 551                         success = 1;
 552                 } else {
 553                         key_free(k);
 554                 }
 555                 keys[i] = NULL;
 556         }
 557         xfree(keys);
 558 send:
 559         buffer_put_int(&e->output, 1);
 560         buffer_put_char(&e->output,
 561             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 562 }
 563
 564 static void
 565 process_remove_smartcard_key(SocketEntry *e)
 566 {
 567         char *sc_reader_id = NULL, *pin;
 568         int i, version, success = 0;
 569         Key **keys, *k = NULL;
 570         Identity *id;
 571         Idtab *tab;
 572
 573         sc_reader_id = buffer_get_string(&e->request, NULL);
 574         pin = buffer_get_string(&e->request, NULL);
 575         keys = sc_get_keys(sc_reader_id, pin);
 576         xfree(sc_reader_id);
 577         xfree(pin);
 578
 579         if (keys == NULL || keys[0] == NULL) {
 580                 error("sc_get_keys failed");
 581                 goto send;
 582         }
 583         for (i = 0; keys[i] != NULL; i++) {
 584                 k = keys[i];
 585                 version = k->type == KEY_RSA1 ? 1 : 2;
 586                 if ((id = lookup_identity(k, version)) != NULL) {
 587                         tab = idtab_lookup(version);
 588                         TAILQ_REMOVE(&tab->idlist, id, next);
 589                         tab->nentries--;
 590                         free_identity(id);
 591                         success = 1;
 592                 }
 593                 key_free(k);
 594                 keys[i] = NULL;
 595         }
 596         xfree(keys);
 597 send:
 598         buffer_put_int(&e->output, 1);
 599         buffer_put_char(&e->output,
 600             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 601 }
 602 #endif /* SMARTCARD */
 603
 604 /* dispatch incoming messages */
 605
 606 static void
 607 process_message(SocketEntry *e)
 608 {
 609         u_int msg_len, type;
 610         u_char *cp;
 611
 612         /* kill dead keys */
 613         reaper();
 614
 615         if (buffer_len(&e->input) < 5)
 616                 return;         /* Incomplete message. */
 617         cp = buffer_ptr(&e->input);
 618         msg_len = GET_32BIT(cp);
 619         if (msg_len > 256 * 1024) {
 620                 shutdown(e->fd, SHUT_RDWR);
 621                 close(e->fd);
 622                 e->fd = -1;
 623                 e->type = AUTH_UNUSED;
 624                 buffer_free(&e->input);
 625                 buffer_free(&e->output);
 626                 buffer_free(&e->request);
 627                 return;
 628         }
 629         if (buffer_len(&e->input) < msg_len + 4)
 630                 return;
 631
 632         /* move the current input to e->request */
 633         buffer_consume(&e->input, 4);
 634         buffer_clear(&e->request);
 635         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 636         buffer_consume(&e->input, msg_len);
 637         type = buffer_get_char(&e->request);
 638
 639         /* check wheter agent is locked */
 640         if (locked && type != SSH_AGENTC_UNLOCK) {
 641                 buffer_clear(&e->request);
 642                 switch (type) {
 643                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 644                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 645                         /* send empty lists */
 646                         no_identities(e, type);
 647                         break;
 648                 default:
 649                         /* send a fail message for all other request types */
 650                         buffer_put_int(&e->output, 1);
 651                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 652                 }
 653                 return;
 654         }
 655
 656         debug("type %d", type);
 657         switch (type) {
 658         case SSH_AGENTC_LOCK:
 659         case SSH_AGENTC_UNLOCK:
 660                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 661                 break;
 662         /* ssh1 */
 663         case SSH_AGENTC_RSA_CHALLENGE:
 664                 process_authentication_challenge1(e);
 665                 break;
 666         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 667                 process_request_identities(e, 1);
 668                 break;
 669         case SSH_AGENTC_ADD_RSA_IDENTITY:
 670         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 671                 process_add_identity(e, 1);
 672                 break;
 673         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 674                 process_remove_identity(e, 1);
 675                 break;
 676         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 677                 process_remove_all_identities(e, 1);
 678                 break;
 679         /* ssh2 */
 680         case SSH2_AGENTC_SIGN_REQUEST:
 681                 process_sign_request2(e);
 682                 break;
 683         case SSH2_AGENTC_REQUEST_IDENTITIES:
 684                 process_request_identities(e, 2);
 685                 break;
 686         case SSH2_AGENTC_ADD_IDENTITY:
 687         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 688                 process_add_identity(e, 2);
 689                 break;
 690         case SSH2_AGENTC_REMOVE_IDENTITY:
 691                 process_remove_identity(e, 2);
 692                 break;
 693         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 694                 process_remove_all_identities(e, 2);
 695                 break;
 696 #ifdef SMARTCARD
 697         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 698                 process_add_smartcard_key(e);
 699                 break;
 700         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 701                 process_remove_smartcard_key(e);
 702                 break;
 703 #endif /* SMARTCARD */
 704         default:
 705                 /* Unknown message.  Respond with failure. */
 706                 error("Unknown message %d", type);
 707                 buffer_clear(&e->request);
 708                 buffer_put_int(&e->output, 1);
 709                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 710                 break;
 711         }
 712 }
 713
 714 static void
 715 new_socket(sock_type type, int fd)
 716 {
 717         u_int i, old_alloc;
 718
 719         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 720                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 721
 722         if (fd > max_fd)
 723                 max_fd = fd;
 724
 725         for (i = 0; i < sockets_alloc; i++)
 726                 if (sockets[i].type == AUTH_UNUSED) {
 727                         sockets[i].fd = fd;
 728                         sockets[i].type = type;
 729                         buffer_init(&sockets[i].input);
 730                         buffer_init(&sockets[i].output);
 731                         buffer_init(&sockets[i].request);
 732                         return;
 733                 }
 734         old_alloc = sockets_alloc;
 735         sockets_alloc += 10;
 736         if (sockets)
 737                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 738         else
 739                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 740         for (i = old_alloc; i < sockets_alloc; i++)
 741                 sockets[i].type = AUTH_UNUSED;
 742         sockets[old_alloc].type = type;
 743         sockets[old_alloc].fd = fd;
 744         buffer_init(&sockets[old_alloc].input);
 745         buffer_init(&sockets[old_alloc].output);
 746         buffer_init(&sockets[old_alloc].request);
 747 }
 748
 749 static int
 750 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 751 {
 752         u_int i, sz;
 753         int n = 0;
 754
 755         for (i = 0; i < sockets_alloc; i++) {
 756                 switch (sockets[i].type) {
 757                 case AUTH_SOCKET:
 758                 case AUTH_CONNECTION:
 759                         n = MAX(n, sockets[i].fd);
 760                         break;
 761                 case AUTH_UNUSED:
 762                         break;
 763                 default:
 764                         fatal("Unknown socket type %d", sockets[i].type);
 765                         break;
 766                 }
 767         }
 768
 769         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 770         if (*fdrp == NULL || sz > *nallocp) {
 771                 if (*fdrp)
 772                         xfree(*fdrp);
 773                 if (*fdwp)
 774                         xfree(*fdwp);
 775                 *fdrp = xmalloc(sz);
 776                 *fdwp = xmalloc(sz);
 777                 *nallocp = sz;
 778         }
 779         if (n < *fdl)
 780                 debug("XXX shrink: %d < %d", n, *fdl);
 781         *fdl = n;
 782         memset(*fdrp, 0, sz);
 783         memset(*fdwp, 0, sz);
 784
 785         for (i = 0; i < sockets_alloc; i++) {
 786                 switch (sockets[i].type) {
 787                 case AUTH_SOCKET:
 788                 case AUTH_CONNECTION:
 789                         FD_SET(sockets[i].fd, *fdrp);
 790                         if (buffer_len(&sockets[i].output) > 0)
 791                                 FD_SET(sockets[i].fd, *fdwp);
 792                         break;
 793                 default:
 794                         break;
 795                 }
 796         }
 797         return (1);
 798 }
 799
 800 static void
 801 after_select(fd_set *readset, fd_set *writeset)
 802 {
 803         struct sockaddr_un sunaddr;
 804         socklen_t slen;
 805         char buf[1024];
 806         int len, sock;
 807         u_int i;
 808
 809         for (i = 0; i < sockets_alloc; i++)
 810                 switch (sockets[i].type) {
 811                 case AUTH_UNUSED:
 812                         break;
 813                 case AUTH_SOCKET:
 814                         if (FD_ISSET(sockets[i].fd, readset)) {
 815                                 slen = sizeof(sunaddr);
 816                                 sock = accept(sockets[i].fd,
 817                                     (struct sockaddr *) &sunaddr, &slen);
 818                                 if (sock < 0) {
 819                                         error("accept from AUTH_SOCKET: %s",
 820                                             strerror(errno));
 821                                         break;
 822                                 }
 823                                 new_socket(AUTH_CONNECTION, sock);
 824                         }
 825                         break;
 826                 case AUTH_CONNECTION:
 827                         if (buffer_len(&sockets[i].output) > 0 &&
 828                             FD_ISSET(sockets[i].fd, writeset)) {
 829                                 do {
 830                                         len = write(sockets[i].fd,
 831                                             buffer_ptr(&sockets[i].output),
 832                                             buffer_len(&sockets[i].output));
 833                                         if (len == -1 && (errno == EAGAIN ||
 834                                             errno == EINTR))
 835                                                 continue;
 836                                         break;
 837                                 } while (1);
 838                                 if (len <= 0) {
 839                                         shutdown(sockets[i].fd, SHUT_RDWR);
 840                                         close(sockets[i].fd);
 841                                         sockets[i].fd = -1;
 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].fd = -1;
 862                                         sockets[i].type = AUTH_UNUSED;
 863                                         buffer_free(&sockets[i].input);
 864                                         buffer_free(&sockets[i].output);
 865                                         buffer_free(&sockets[i].request);
 866                                         break;
 867                                 }
 868                                 buffer_append(&sockets[i].input, buf, len);
 869                                 process_message(&sockets[i]);
 870                         }
 871                         break;
 872                 default:
 873                         fatal("Unknown type %d", sockets[i].type);
 874                 }
 875 }
 876
 877 static void
 878 cleanup_socket(void *p)
 879 {
 880         if (socket_name[0])
 881                 unlink(socket_name);
 882         if (socket_dir[0])
 883                 rmdir(socket_dir);
 884 }
 885
 886 static void
 887 cleanup_exit(int i)
 888 {
 889         cleanup_socket(NULL);
 890         exit(i);
 891 }
 892
 893 static void
 894 cleanup_handler(int sig)
 895 {
 896         cleanup_socket(NULL);
 897         _exit(2);
 898 }
 899
 900 static void
 901 check_parent_exists(int sig)
 902 {
 903         int save_errno = errno;
 904
 905         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 906                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 907                 cleanup_handler(sig); /* safe */
 908         }
 909         signal(SIGALRM, check_parent_exists);
 910         alarm(10);
 911         errno = save_errno;
 912 }
 913
 914 static void
 915 usage(void)
 916 {
 917         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 918             __progname);
 919         fprintf(stderr, "Options:\n");
 920         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 921         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 922         fprintf(stderr, "  -k          Kill the current agent.\n");
 923         fprintf(stderr, "  -d          Debug mode.\n");
 924         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 925         exit(1);
 926 }
 927
 928 int
 929 main(int ac, char **av)
 930 {
 931         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 932         char *shell, *format, *pidstr, *agentsocket = NULL;
 933         fd_set *readsetp = NULL, *writesetp = NULL;
 934         struct sockaddr_un sunaddr;
 935 #ifdef HAVE_SETRLIMIT
 936         struct rlimit rlim;
 937 #endif
 938 #ifdef HAVE_CYGWIN
 939         int prev_mask;
 940 #endif
 941         extern int optind;
 942         extern char *optarg;
 943         pid_t pid;
 944         char pidstrbuf[1 + 3 * sizeof pid];
 945
 946         SSLeay_add_all_algorithms();
 947
 948         __progname = get_progname(av[0]);
 949         init_rng();
 950         seed_rng();
 951
 952         while ((ch = getopt(ac, av, "cdksa:")) != -1) {
 953                 switch (ch) {
 954                 case 'c':
 955                         if (s_flag)
 956                                 usage();
 957                         c_flag++;
 958                         break;
 959                 case 'k':
 960                         k_flag++;
 961                         break;
 962                 case 's':
 963                         if (c_flag)
 964                                 usage();
 965                         s_flag++;
 966                         break;
 967                 case 'd':
 968                         if (d_flag)
 969                                 usage();
 970                         d_flag++;
 971                         break;
 972                 case 'a':
 973                         agentsocket = optarg;
 974                         break;
 975                 default:
 976                         usage();
 977                 }
 978         }
 979         ac -= optind;
 980         av += optind;
 981
 982         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
 983                 usage();
 984
 985         if (ac == 0 && !c_flag && !s_flag) {
 986                 shell = getenv("SHELL");
 987                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 988                         c_flag = 1;
 989         }
 990         if (k_flag) {
 991                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 992                 if (pidstr == NULL) {
 993                         fprintf(stderr, "%s not set, cannot kill agent\n",
 994                             SSH_AGENTPID_ENV_NAME);
 995                         exit(1);
 996                 }
 997                 pid = atoi(pidstr);
 998                 if (pid < 1) {
 999                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
1000                             SSH_AGENTPID_ENV_NAME, pidstr);
1001                         exit(1);
1002                 }
1003                 if (kill(pid, SIGTERM) == -1) {
1004                         perror("kill");
1005                         exit(1);
1006                 }
1007                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1008                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1009                 printf(format, SSH_AGENTPID_ENV_NAME);
1010                 printf("echo Agent pid %ld killed;\n", (long)pid);
1011                 exit(0);
1012         }
1013         parent_pid = getpid();
1014
1015         if (agentsocket == NULL) {
1016                 /* Create private directory for agent socket */
1017                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
1018                 if (mkdtemp(socket_dir) == NULL) {
1019                         perror("mkdtemp: private socket dir");
1020                         exit(1);
1021                 }
1022                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1023                     (long)parent_pid);
1024         } else {
1025                 /* Try to use specified agent socket */
1026                 socket_dir[0] = '\0';
1027                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1028         }
1029
1030         /*
1031          * Create socket early so it will exist before command gets run from
1032          * the parent.
1033          */
1034         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1035         if (sock < 0) {
1036                 perror("socket");
1037                 cleanup_exit(1);
1038         }
1039         memset(&sunaddr, 0, sizeof(sunaddr));
1040         sunaddr.sun_family = AF_UNIX;
1041         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1042 #ifdef HAVE_CYGWIN
1043         prev_mask = umask(0177);
1044 #endif
1045         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1046                 perror("bind");
1047 #ifdef HAVE_CYGWIN
1048                 umask(prev_mask);
1049 #endif
1050                 cleanup_exit(1);
1051         }
1052 #ifdef HAVE_CYGWIN
1053         umask(prev_mask);
1054 #endif
1055         if (listen(sock, 5) < 0) {
1056                 perror("listen");
1057                 cleanup_exit(1);
1058         }
1059
1060         /*
1061          * Fork, and have the parent execute the command, if any, or present
1062          * the socket data.  The child continues as the authentication agent.
1063          */
1064         if (d_flag) {
1065                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1066                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1067                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1068                     SSH_AUTHSOCKET_ENV_NAME);
1069                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1070                 goto skip;
1071         }
1072         pid = fork();
1073         if (pid == -1) {
1074                 perror("fork");
1075                 cleanup_exit(1);
1076         }
1077         if (pid != 0) {         /* Parent - execute the given command. */
1078                 close(sock);
1079                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1080                 if (ac == 0) {
1081                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1082                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1083                             SSH_AUTHSOCKET_ENV_NAME);
1084                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1085                             SSH_AGENTPID_ENV_NAME);
1086                         printf("echo Agent pid %ld;\n", (long)pid);
1087                         exit(0);
1088                 }
1089                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1090                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1091                         perror("setenv");
1092                         exit(1);
1093                 }
1094                 execvp(av[0], av);
1095                 perror(av[0]);
1096                 exit(1);
1097         }
1098         /* child */
1099         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1100
1101         if (setsid() == -1) {
1102                 error("setsid: %s", strerror(errno));
1103                 cleanup_exit(1);
1104         }
1105
1106         (void)chdir("/");
1107         close(0);
1108         close(1);
1109         close(2);
1110
1111 #ifdef HAVE_SETRLIMIT
1112         /* deny core dumps, since memory contains unencrypted private keys */
1113         rlim.rlim_cur = rlim.rlim_max = 0;
1114         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1115                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1116                 cleanup_exit(1);
1117         }
1118 #endif
1119
1120 skip:
1121         fatal_add_cleanup(cleanup_socket, NULL);
1122         new_socket(AUTH_SOCKET, sock);
1123         if (ac > 0) {
1124                 signal(SIGALRM, check_parent_exists);
1125                 alarm(10);
1126         }
1127         idtab_init();
1128         if (!d_flag)
1129                 signal(SIGINT, SIG_IGN);
1130         signal(SIGPIPE, SIG_IGN);
1131         signal(SIGHUP, cleanup_handler);
1132         signal(SIGTERM, cleanup_handler);
1133         nalloc = 0;
1134
1135         while (1) {
1136                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1137                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1138                         if (errno == EINTR)
1139                                 continue;
1140                         fatal("select: %s", strerror(errno));
1141                 }
1142                 after_select(readsetp, writesetp);
1143         }
1144         /* NOTREACHED */
1145 }