ssh-agent.c

   1 /*      $OpenBSD: ssh-agent.c,v 1.48 2001/01/25 08:06:33 deraadt Exp $  */
   2
   3 /*
   4  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   5  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   6  *                    All rights reserved
   7  * The authentication agent program.
   8  *
   9  * As far as I am concerned, the code I have written for this software
  10  * can be used freely for any purpose.  Any derived versions of this
  11  * software must be clearly marked as such, and if the derived work is
  12  * incompatible with the protocol description in the RFC file, it must be
  13  * called by a name other than "ssh" or "Secure Shell".
  14  *
  15  * SSH2 implementation,
  16  * Copyright (c) 2000 Markus Friedl. All rights reserved.
  17  *
  18  * Redistribution and use in source and binary forms, with or without
  19  * modification, are permitted provided that the following conditions
  20  * are met:
  21  * 1. Redistributions of source code must retain the above copyright
  22  *    notice, this list of conditions and the following disclaimer.
  23  * 2. Redistributions in binary form must reproduce the above copyright
  24  *    notice, this list of conditions and the following disclaimer in the
  25  *    documentation and/or other materials provided with the distribution.
  26  *
  27  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  28  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  29  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  30  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  31  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  32  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  33  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  34  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  35  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  36  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  37  */
  38
  39 #include "includes.h"
  40 RCSID("$OpenBSD: ssh-agent.c,v 1.48 2001/01/25 08:06:33 deraadt Exp $");
  41
  42 #include <openssl/evp.h>
  43 #include <openssl/md5.h>
  44
  45 #include "ssh.h"
  46 #include "rsa.h"
  47 #include "buffer.h"
  48 #include "bufaux.h"
  49 #include "xmalloc.h"
  50 #include "packet.h"
  51 #include "getput.h"
  52 #include "mpaux.h"
  53 #include "key.h"
  54 #include "authfd.h"
  55 #include "cipher.h"
  56 #include "kex.h"
  57 #include "compat.h"
  58 #include "log.h"
  59
  60 typedef struct {
  61         int fd;
  62         enum {
  63                 AUTH_UNUSED, AUTH_SOCKET, AUTH_CONNECTION
  64         } type;
  65         Buffer input;
  66         Buffer output;
  67 } SocketEntry;
  68
  69 u_int sockets_alloc = 0;
  70 SocketEntry *sockets = NULL;
  71
  72 typedef struct {
  73         Key *key;
  74         char *comment;
  75 } Identity;
  76
  77 typedef struct {
  78         int nentries;
  79         Identity *identities;
  80 } Idtab;
  81
  82 /* private key table, one per protocol version */
  83 Idtab idtable[3];
  84
  85 int max_fd = 0;
  86
  87 /* pid of shell == parent of agent */
  88 pid_t parent_pid = -1;
  89
  90 /* pathname and directory for AUTH_SOCKET */
  91 char socket_name[1024];
  92 char socket_dir[1024];
  93
  94 #ifdef HAVE___PROGNAME
  95 extern char *__progname;
  96 #else
  97 char *__progname;
  98 #endif
  99
 100 int     prepare_select(fd_set **, fd_set **, int *);
 101
 102 void
 103 idtab_init(void)
 104 {
 105         int i;
 106         for (i = 0; i <=2; i++){
 107                 idtable[i].identities = NULL;
 108                 idtable[i].nentries = 0;
 109         }
 110 }
 111
 112 /* return private key table for requested protocol version */
 113 Idtab *
 114 idtab_lookup(int version)
 115 {
 116         if (version < 1 || version > 2)
 117                 fatal("internal error, bad protocol version %d", version);
 118         return &idtable[version];
 119 }
 120
 121 /* return matching private key for given public key */
 122 Key *
 123 lookup_private_key(Key *key, int *idx, int version)
 124 {
 125         int i;
 126         Idtab *tab = idtab_lookup(version);
 127         for (i = 0; i < tab->nentries; i++) {
 128                 if (key_equal(key, tab->identities[i].key)) {
 129                         if (idx != NULL)
 130                                 *idx = i;
 131                         return tab->identities[i].key;
 132                 }
 133         }
 134         return NULL;
 135 }
 136
 137 /* send list of supported public keys to 'client' */
 138 void
 139 process_request_identities(SocketEntry *e, int version)
 140 {
 141         Idtab *tab = idtab_lookup(version);
 142         Buffer msg;
 143         int i;
 144
 145         buffer_init(&msg);
 146         buffer_put_char(&msg, (version == 1) ?
 147             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 148         buffer_put_int(&msg, tab->nentries);
 149         for (i = 0; i < tab->nentries; i++) {
 150                 Identity *id = &tab->identities[i];
 151                 if (id->key->type == KEY_RSA1) {
 152                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 153                         buffer_put_bignum(&msg, id->key->rsa->e);
 154                         buffer_put_bignum(&msg, id->key->rsa->n);
 155                 } else {
 156                         u_char *blob;
 157                         u_int blen;
 158                         key_to_blob(id->key, &blob, &blen);
 159                         buffer_put_string(&msg, blob, blen);
 160                         xfree(blob);
 161                 }
 162                 buffer_put_cstring(&msg, id->comment);
 163         }
 164         buffer_put_int(&e->output, buffer_len(&msg));
 165         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 166         buffer_free(&msg);
 167 }
 168
 169 /* ssh1 only */
 170 void
 171 process_authentication_challenge1(SocketEntry *e)
 172 {
 173         Key *key, *private;
 174         BIGNUM *challenge;
 175         int i, len;
 176         Buffer msg;
 177         MD5_CTX md;
 178         u_char buf[32], mdbuf[16], session_id[16];
 179         u_int response_type;
 180
 181         buffer_init(&msg);
 182         key = key_new(KEY_RSA1);
 183         challenge = BN_new();
 184
 185         buffer_get_int(&e->input);                              /* ignored */
 186         buffer_get_bignum(&e->input, key->rsa->e);
 187         buffer_get_bignum(&e->input, key->rsa->n);
 188         buffer_get_bignum(&e->input, challenge);
 189
 190         /* Only protocol 1.1 is supported */
 191         if (buffer_len(&e->input) == 0)
 192                 goto failure;
 193         buffer_get(&e->input, (char *) session_id, 16);
 194         response_type = buffer_get_int(&e->input);
 195         if (response_type != 1)
 196                 goto failure;
 197
 198         private = lookup_private_key(key, NULL, 1);
 199         if (private != NULL) {
 200                 /* Decrypt the challenge using the private key. */
 201                 rsa_private_decrypt(challenge, challenge, private->rsa);
 202
 203                 /* The response is MD5 of decrypted challenge plus session id. */
 204                 len = BN_num_bytes(challenge);
 205                 if (len <= 0 || len > 32) {
 206                         log("process_authentication_challenge: bad challenge length %d", len);
 207                         goto failure;
 208                 }
 209                 memset(buf, 0, 32);
 210                 BN_bn2bin(challenge, buf + 32 - len);
 211                 MD5_Init(&md);
 212                 MD5_Update(&md, buf, 32);
 213                 MD5_Update(&md, session_id, 16);
 214                 MD5_Final(mdbuf, &md);
 215
 216                 /* Send the response. */
 217                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 218                 for (i = 0; i < 16; i++)
 219                         buffer_put_char(&msg, mdbuf[i]);
 220                 goto send;
 221         }
 222
 223 failure:
 224         /* Unknown identity or protocol error.  Send failure. */
 225         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 226 send:
 227         buffer_put_int(&e->output, buffer_len(&msg));
 228         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 229         key_free(key);
 230         BN_clear_free(challenge);
 231         buffer_free(&msg);
 232 }
 233
 234 /* ssh2 only */
 235 void
 236 process_sign_request2(SocketEntry *e)
 237 {
 238         extern int datafellows;
 239         Key *key, *private;
 240         u_char *blob, *data, *signature = NULL;
 241         u_int blen, dlen, slen = 0;
 242         int flags;
 243         Buffer msg;
 244         int ok = -1;
 245
 246         datafellows = 0;
 247
 248         blob = buffer_get_string(&e->input, &blen);
 249         data = buffer_get_string(&e->input, &dlen);
 250
 251         flags = buffer_get_int(&e->input);
 252         if (flags & SSH_AGENT_OLD_SIGNATURE)
 253                 datafellows = SSH_BUG_SIGBLOB;
 254
 255         key = key_from_blob(blob, blen);
 256         if (key != NULL) {
 257                 private = lookup_private_key(key, NULL, 2);
 258                 if (private != NULL)
 259                         ok = key_sign(private, &signature, &slen, data, dlen);
 260         }
 261         key_free(key);
 262         buffer_init(&msg);
 263         if (ok == 0) {
 264                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 265                 buffer_put_string(&msg, signature, slen);
 266         } else {
 267                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 268         }
 269         buffer_put_int(&e->output, buffer_len(&msg));
 270         buffer_append(&e->output, buffer_ptr(&msg),
 271             buffer_len(&msg));
 272         buffer_free(&msg);
 273         xfree(data);
 274         xfree(blob);
 275         if (signature != NULL)
 276                 xfree(signature);
 277 }
 278
 279 /* shared */
 280 void
 281 process_remove_identity(SocketEntry *e, int version)
 282 {
 283         Key *key = NULL, *private;
 284         u_char *blob;
 285         u_int blen;
 286         u_int bits;
 287         int success = 0;
 288
 289         switch(version){
 290         case 1:
 291                 key = key_new(KEY_RSA1);
 292                 bits = buffer_get_int(&e->input);
 293                 buffer_get_bignum(&e->input, key->rsa->e);
 294                 buffer_get_bignum(&e->input, key->rsa->n);
 295
 296                 if (bits != key_size(key))
 297                         log("Warning: identity keysize mismatch: actual %d, announced %d",
 298                             key_size(key), bits);
 299                 break;
 300         case 2:
 301                 blob = buffer_get_string(&e->input, &blen);
 302                 key = key_from_blob(blob, blen);
 303                 xfree(blob);
 304                 break;
 305         }
 306         if (key != NULL) {
 307                 int idx;
 308                 private = lookup_private_key(key, &idx, version);
 309                 if (private != NULL) {
 310                         /*
 311                          * We have this key.  Free the old key.  Since we
 312                          * don\'t want to leave empty slots in the middle of
 313                          * the array, we actually free the key there and move
 314                          * all the entries between the empty slot and the end
 315                          * of the array.
 316                          */
 317                         Idtab *tab = idtab_lookup(version);
 318                         key_free(tab->identities[idx].key);
 319                         xfree(tab->identities[idx].comment);
 320                         if (tab->nentries < 1)
 321                                 fatal("process_remove_identity: "
 322                                     "internal error: tab->nentries %d",
 323                                     tab->nentries);
 324                         if (idx != tab->nentries - 1) {
 325                                 int i;
 326                                 for (i = idx; i < tab->nentries - 1; i++)
 327                                         tab->identities[i] = tab->identities[i+1];
 328                         }
 329                         tab->identities[tab->nentries - 1].key = NULL;
 330                         tab->identities[tab->nentries - 1].comment = NULL;
 331                         tab->nentries--;
 332                         success = 1;
 333                 }
 334                 key_free(key);
 335         }
 336         buffer_put_int(&e->output, 1);
 337         buffer_put_char(&e->output,
 338             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 339 }
 340
 341 void
 342 process_remove_all_identities(SocketEntry *e, int version)
 343 {
 344         u_int i;
 345         Idtab *tab = idtab_lookup(version);
 346
 347         /* Loop over all identities and clear the keys. */
 348         for (i = 0; i < tab->nentries; i++) {
 349                 key_free(tab->identities[i].key);
 350                 xfree(tab->identities[i].comment);
 351         }
 352
 353         /* Mark that there are no identities. */
 354         tab->nentries = 0;
 355
 356         /* Send success. */
 357         buffer_put_int(&e->output, 1);
 358         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 359         return;
 360 }
 361
 362 void
 363 generate_additional_parameters(RSA *rsa)
 364 {
 365         BIGNUM *aux;
 366         BN_CTX *ctx;
 367         /* Generate additional parameters */
 368         aux = BN_new();
 369         ctx = BN_CTX_new();
 370
 371         BN_sub(aux, rsa->q, BN_value_one());
 372         BN_mod(rsa->dmq1, rsa->d, aux, ctx);
 373
 374         BN_sub(aux, rsa->p, BN_value_one());
 375         BN_mod(rsa->dmp1, rsa->d, aux, ctx);
 376
 377         BN_clear_free(aux);
 378         BN_CTX_free(ctx);
 379 }
 380
 381 void
 382 process_add_identity(SocketEntry *e, int version)
 383 {
 384         Key *k = NULL;
 385         char *type_name;
 386         char *comment;
 387         int type, success = 0;
 388         Idtab *tab = idtab_lookup(version);
 389
 390         switch (version) {
 391         case 1:
 392                 k = key_new_private(KEY_RSA1);
 393                 buffer_get_int(&e->input);                      /* ignored */
 394                 buffer_get_bignum(&e->input, k->rsa->n);
 395                 buffer_get_bignum(&e->input, k->rsa->e);
 396                 buffer_get_bignum(&e->input, k->rsa->d);
 397                 buffer_get_bignum(&e->input, k->rsa->iqmp);
 398
 399                 /* SSH and SSL have p and q swapped */
 400                 buffer_get_bignum(&e->input, k->rsa->q);        /* p */
 401                 buffer_get_bignum(&e->input, k->rsa->p);        /* q */
 402
 403                 /* Generate additional parameters */
 404                 generate_additional_parameters(k->rsa);
 405                 break;
 406         case 2:
 407                 type_name = buffer_get_string(&e->input, NULL);
 408                 type = key_type_from_name(type_name);
 409                 xfree(type_name);
 410                 switch(type) {
 411                 case KEY_DSA:
 412                         k = key_new_private(type);
 413                         buffer_get_bignum2(&e->input, k->dsa->p);
 414                         buffer_get_bignum2(&e->input, k->dsa->q);
 415                         buffer_get_bignum2(&e->input, k->dsa->g);
 416                         buffer_get_bignum2(&e->input, k->dsa->pub_key);
 417                         buffer_get_bignum2(&e->input, k->dsa->priv_key);
 418                         break;
 419                 case KEY_RSA:
 420                         k = key_new_private(type);
 421                         buffer_get_bignum2(&e->input, k->rsa->n);
 422                         buffer_get_bignum2(&e->input, k->rsa->e);
 423                         buffer_get_bignum2(&e->input, k->rsa->d);
 424                         buffer_get_bignum2(&e->input, k->rsa->iqmp);
 425                         buffer_get_bignum2(&e->input, k->rsa->p);
 426                         buffer_get_bignum2(&e->input, k->rsa->q);
 427
 428                         /* Generate additional parameters */
 429                         generate_additional_parameters(k->rsa);
 430                         break;
 431                 default:
 432                         buffer_clear(&e->input);
 433                         goto send;
 434                 }
 435                 break;
 436         }
 437         comment = buffer_get_string(&e->input, NULL);
 438         if (k == NULL) {
 439                 xfree(comment);
 440                 goto send;
 441         }
 442         success = 1;
 443         if (lookup_private_key(k, NULL, version) == NULL) {
 444                 if (tab->nentries == 0)
 445                         tab->identities = xmalloc(sizeof(Identity));
 446                 else
 447                         tab->identities = xrealloc(tab->identities,
 448                             (tab->nentries + 1) * sizeof(Identity));
 449                 tab->identities[tab->nentries].key = k;
 450                 tab->identities[tab->nentries].comment = comment;
 451                 /* Increment the number of identities. */
 452                 tab->nentries++;
 453         } else {
 454                 key_free(k);
 455                 xfree(comment);
 456         }
 457 send:
 458         buffer_put_int(&e->output, 1);
 459         buffer_put_char(&e->output,
 460             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 461 }
 462
 463 /* dispatch incoming messages */
 464
 465 void
 466 process_message(SocketEntry *e)
 467 {
 468         u_int msg_len;
 469         u_int type;
 470         u_char *cp;
 471         if (buffer_len(&e->input) < 5)
 472                 return;         /* Incomplete message. */
 473         cp = (u_char *) buffer_ptr(&e->input);
 474         msg_len = GET_32BIT(cp);
 475         if (msg_len > 256 * 1024) {
 476                 shutdown(e->fd, SHUT_RDWR);
 477                 close(e->fd);
 478                 e->type = AUTH_UNUSED;
 479                 return;
 480         }
 481         if (buffer_len(&e->input) < msg_len + 4)
 482                 return;
 483         buffer_consume(&e->input, 4);
 484         type = buffer_get_char(&e->input);
 485
 486         switch (type) {
 487         /* ssh1 */
 488         case SSH_AGENTC_RSA_CHALLENGE:
 489                 process_authentication_challenge1(e);
 490                 break;
 491         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 492                 process_request_identities(e, 1);
 493                 break;
 494         case SSH_AGENTC_ADD_RSA_IDENTITY:
 495                 process_add_identity(e, 1);
 496                 break;
 497         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 498                 process_remove_identity(e, 1);
 499                 break;
 500         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 501                 process_remove_all_identities(e, 1);
 502                 break;
 503         /* ssh2 */
 504         case SSH2_AGENTC_SIGN_REQUEST:
 505                 process_sign_request2(e);
 506                 break;
 507         case SSH2_AGENTC_REQUEST_IDENTITIES:
 508                 process_request_identities(e, 2);
 509                 break;
 510         case SSH2_AGENTC_ADD_IDENTITY:
 511                 process_add_identity(e, 2);
 512                 break;
 513         case SSH2_AGENTC_REMOVE_IDENTITY:
 514                 process_remove_identity(e, 2);
 515                 break;
 516         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 517                 process_remove_all_identities(e, 2);
 518                 break;
 519         default:
 520                 /* Unknown message.  Respond with failure. */
 521                 error("Unknown message %d", type);
 522                 buffer_clear(&e->input);
 523                 buffer_put_int(&e->output, 1);
 524                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 525                 break;
 526         }
 527 }
 528
 529 void
 530 new_socket(int type, int fd)
 531 {
 532         u_int i, old_alloc;
 533         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 534                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 535
 536         if (fd > max_fd)
 537                 max_fd = fd;
 538
 539         for (i = 0; i < sockets_alloc; i++)
 540                 if (sockets[i].type == AUTH_UNUSED) {
 541                         sockets[i].fd = fd;
 542                         sockets[i].type = type;
 543                         buffer_init(&sockets[i].input);
 544                         buffer_init(&sockets[i].output);
 545                         return;
 546                 }
 547         old_alloc = sockets_alloc;
 548         sockets_alloc += 10;
 549         if (sockets)
 550                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 551         else
 552                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 553         for (i = old_alloc; i < sockets_alloc; i++)
 554                 sockets[i].type = AUTH_UNUSED;
 555         sockets[old_alloc].type = type;
 556         sockets[old_alloc].fd = fd;
 557         buffer_init(&sockets[old_alloc].input);
 558         buffer_init(&sockets[old_alloc].output);
 559 }
 560
 561 int
 562 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl)
 563 {
 564         u_int i, sz;
 565         int n = 0;
 566
 567         for (i = 0; i < sockets_alloc; i++) {
 568                 switch (sockets[i].type) {
 569                 case AUTH_SOCKET:
 570                 case AUTH_CONNECTION:
 571                         n = MAX(n, sockets[i].fd);
 572                         break;
 573                 case AUTH_UNUSED:
 574                         break;
 575                 default:
 576                         fatal("Unknown socket type %d", sockets[i].type);
 577                         break;
 578                 }
 579         }
 580
 581         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 582         if (*fdrp == NULL || n > *fdl) {
 583                 if (*fdrp)
 584                         free(*fdrp);
 585                 if (*fdwp)
 586                         free(*fdwp);
 587                 *fdrp = xmalloc(sz);
 588                 *fdwp = xmalloc(sz);
 589                 *fdl = n;
 590         }
 591         memset(*fdrp, 0, sz);
 592         memset(*fdwp, 0, sz);
 593
 594         for (i = 0; i < sockets_alloc; i++) {
 595                 switch (sockets[i].type) {
 596                 case AUTH_SOCKET:
 597                 case AUTH_CONNECTION:
 598                         FD_SET(sockets[i].fd, *fdrp);
 599                         if (buffer_len(&sockets[i].output) > 0)
 600                                 FD_SET(sockets[i].fd, *fdwp);
 601                         break;
 602                 default:
 603                         break;
 604                 }
 605         }
 606         return (1);
 607 }
 608
 609 void
 610 after_select(fd_set *readset, fd_set *writeset)
 611 {
 612         u_int i;
 613         int len, sock;
 614         socklen_t slen;
 615         char buf[1024];
 616         struct sockaddr_un sunaddr;
 617
 618         for (i = 0; i < sockets_alloc; i++)
 619                 switch (sockets[i].type) {
 620                 case AUTH_UNUSED:
 621                         break;
 622                 case AUTH_SOCKET:
 623                         if (FD_ISSET(sockets[i].fd, readset)) {
 624                                 slen = sizeof(sunaddr);
 625                                 sock = accept(sockets[i].fd,
 626                                     (struct sockaddr *) &sunaddr, &slen);
 627                                 if (sock < 0) {
 628                                         perror("accept from AUTH_SOCKET");
 629                                         break;
 630                                 }
 631                                 new_socket(AUTH_CONNECTION, sock);
 632                         }
 633                         break;
 634                 case AUTH_CONNECTION:
 635                         if (buffer_len(&sockets[i].output) > 0 &&
 636                             FD_ISSET(sockets[i].fd, writeset)) {
 637                                 len = write(sockets[i].fd,
 638                                     buffer_ptr(&sockets[i].output),
 639                                     buffer_len(&sockets[i].output));
 640                                 if (len <= 0) {
 641                                         shutdown(sockets[i].fd, SHUT_RDWR);
 642                                         close(sockets[i].fd);
 643                                         sockets[i].type = AUTH_UNUSED;
 644                                         buffer_free(&sockets[i].input);
 645                                         buffer_free(&sockets[i].output);
 646                                         break;
 647                                 }
 648                                 buffer_consume(&sockets[i].output, len);
 649                         }
 650                         if (FD_ISSET(sockets[i].fd, readset)) {
 651                                 len = read(sockets[i].fd, buf, sizeof(buf));
 652                                 if (len <= 0) {
 653                                         shutdown(sockets[i].fd, SHUT_RDWR);
 654                                         close(sockets[i].fd);
 655                                         sockets[i].type = AUTH_UNUSED;
 656                                         buffer_free(&sockets[i].input);
 657                                         buffer_free(&sockets[i].output);
 658                                         break;
 659                                 }
 660                                 buffer_append(&sockets[i].input, buf, len);
 661                                 process_message(&sockets[i]);
 662                         }
 663                         break;
 664                 default:
 665                         fatal("Unknown type %d", sockets[i].type);
 666                 }
 667 }
 668
 669 void
 670 check_parent_exists(int sig)
 671 {
 672         int save_errno = errno;
 673
 674         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 675                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 676                 exit(1);
 677         }
 678         signal(SIGALRM, check_parent_exists);
 679         alarm(10);
 680         errno = save_errno;
 681 }
 682
 683 void
 684 cleanup_socket(void)
 685 {
 686         if (socket_name[0])
 687                 unlink(socket_name);
 688         if (socket_dir[0])
 689                 rmdir(socket_dir);
 690 }
 691
 692 void
 693 cleanup_exit(int i)
 694 {
 695         cleanup_socket();
 696         exit(i);
 697 }
 698
 699 void
 700 cleanup_handler(int sig)
 701 {
 702         cleanup_socket();
 703         _exit(2);
 704 }
 705
 706 void
 707 usage()
 708 {
 709         fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION);
 710         fprintf(stderr, "Usage: %s [-c | -s] [-k] [command {args...]]\n",
 711             __progname);
 712         exit(1);
 713 }
 714
 715 int
 716 main(int ac, char **av)
 717 {
 718         int sock, c_flag = 0, k_flag = 0, s_flag = 0, ch;
 719         struct sockaddr_un sunaddr;
 720 #ifdef HAVE_SETRLIMIT
 721         struct rlimit rlim;
 722 #endif
 723         pid_t pid;
 724         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 725         extern int optind;
 726         fd_set *readsetp = NULL, *writesetp = NULL;
 727
 728         __progname = get_progname(av[0]);
 729         init_rng();
 730
 731 #ifdef __GNU_LIBRARY__
 732         while ((ch = getopt(ac, av, "+cks")) != -1) {
 733 #else /* __GNU_LIBRARY__ */
 734         while ((ch = getopt(ac, av, "cks")) != -1) {
 735 #endif /* __GNU_LIBRARY__ */
 736                 switch (ch) {
 737                 case 'c':
 738                         if (s_flag)
 739                                 usage();
 740                         c_flag++;
 741                         break;
 742                 case 'k':
 743                         k_flag++;
 744                         break;
 745                 case 's':
 746                         if (c_flag)
 747                                 usage();
 748                         s_flag++;
 749                         break;
 750                 default:
 751                         usage();
 752                 }
 753         }
 754         ac -= optind;
 755         av += optind;
 756
 757         if (ac > 0 && (c_flag || k_flag || s_flag))
 758                 usage();
 759
 760         if (ac == 0 && !c_flag && !k_flag && !s_flag) {
 761                 shell = getenv("SHELL");
 762                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 763                         c_flag = 1;
 764         }
 765         if (k_flag) {
 766                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 767                 if (pidstr == NULL) {
 768                         fprintf(stderr, "%s not set, cannot kill agent\n",
 769                             SSH_AGENTPID_ENV_NAME);
 770                         exit(1);
 771                 }
 772                 pid = atoi(pidstr);
 773                 if (pid < 1) {
 774                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 775                             SSH_AGENTPID_ENV_NAME, pidstr);
 776                         exit(1);
 777                 }
 778                 if (kill(pid, SIGTERM) == -1) {
 779                         perror("kill");
 780                         exit(1);
 781                 }
 782                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 783                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 784                 printf(format, SSH_AGENTPID_ENV_NAME);
 785                 printf("echo Agent pid %d killed;\n", pid);
 786                 exit(0);
 787         }
 788         parent_pid = getpid();
 789
 790         /* Create private directory for agent socket */
 791         strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 792         if (mkdtemp(socket_dir) == NULL) {
 793                 perror("mkdtemp: private socket dir");
 794                 exit(1);
 795         }
 796         snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 797             parent_pid);
 798
 799         /*
 800          * Create socket early so it will exist before command gets run from
 801          * the parent.
 802          */
 803         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 804         if (sock < 0) {
 805                 perror("socket");
 806                 cleanup_exit(1);
 807         }
 808         memset(&sunaddr, 0, sizeof(sunaddr));
 809         sunaddr.sun_family = AF_UNIX;
 810         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 811         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 812                 perror("bind");
 813                 cleanup_exit(1);
 814         }
 815         if (listen(sock, 5) < 0) {
 816                 perror("listen");
 817                 cleanup_exit(1);
 818         }
 819
 820         /*
 821          * Fork, and have the parent execute the command, if any, or present
 822          * the socket data.  The child continues as the authentication agent.
 823          */
 824         pid = fork();
 825         if (pid == -1) {
 826                 perror("fork");
 827                 exit(1);
 828         }
 829         if (pid != 0) {         /* Parent - execute the given command. */
 830                 close(sock);
 831                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 832                 if (ac == 0) {
 833                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 834                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 835                             SSH_AUTHSOCKET_ENV_NAME);
 836                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 837                             SSH_AGENTPID_ENV_NAME);
 838                         printf("echo Agent pid %d;\n", pid);
 839                         exit(0);
 840                 }
 841                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 842                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 843                         perror("setenv");
 844                         exit(1);
 845                 }
 846                 execvp(av[0], av);
 847                 perror(av[0]);
 848                 exit(1);
 849         }
 850         close(0);
 851         close(1);
 852         close(2);
 853
 854 #ifdef HAVE_SETRLIMIT
 855         /* deny core dumps, since memory contains unencrypted private keys */
 856         rlim.rlim_cur = rlim.rlim_max = 0;
 857         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
 858                 perror("setrlimit rlimit_core failed");
 859                 cleanup_exit(1);
 860         }
 861 #endif
 862         if (setsid() == -1) {
 863                 perror("setsid");
 864                 cleanup_exit(1);
 865         }
 866         if (atexit(cleanup_socket) < 0) {
 867                 perror("atexit");
 868                 cleanup_exit(1);
 869         }
 870         new_socket(AUTH_SOCKET, sock);
 871         if (ac > 0) {
 872                 signal(SIGALRM, check_parent_exists);
 873                 alarm(10);
 874         }
 875         idtab_init();
 876         signal(SIGINT, SIG_IGN);
 877         signal(SIGPIPE, SIG_IGN);
 878         signal(SIGHUP, cleanup_handler);
 879         signal(SIGTERM, cleanup_handler);
 880         while (1) {
 881                 prepare_select(&readsetp, &writesetp, &max_fd);
 882                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
 883                         if (errno == EINTR)
 884                                 continue;
 885                         exit(1);
 886                 }
 887                 after_select(readsetp, writesetp);
 888         }
 889         /* NOTREACHED */
 890 }