ssh-agent.c

   1 /*      $OpenBSD: ssh-agent.c,v 1.51 2001/03/02 18:54:31 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 1.51 2001/03/02 18:54:31 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                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 202                         goto failure;
 203
 204                 /* The response is MD5 of decrypted challenge plus session id. */
 205                 len = BN_num_bytes(challenge);
 206                 if (len <= 0 || len > 32) {
 207                         log("process_authentication_challenge: bad challenge length %d", len);
 208                         goto failure;
 209                 }
 210                 memset(buf, 0, 32);
 211                 BN_bn2bin(challenge, buf + 32 - len);
 212                 MD5_Init(&md);
 213                 MD5_Update(&md, buf, 32);
 214                 MD5_Update(&md, session_id, 16);
 215                 MD5_Final(mdbuf, &md);
 216
 217                 /* Send the response. */
 218                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 219                 for (i = 0; i < 16; i++)
 220                         buffer_put_char(&msg, mdbuf[i]);
 221                 goto send;
 222         }
 223
 224 failure:
 225         /* Unknown identity or protocol error.  Send failure. */
 226         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 227 send:
 228         buffer_put_int(&e->output, buffer_len(&msg));
 229         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 230         key_free(key);
 231         BN_clear_free(challenge);
 232         buffer_free(&msg);
 233 }
 234
 235 /* ssh2 only */
 236 void
 237 process_sign_request2(SocketEntry *e)
 238 {
 239         extern int datafellows;
 240         Key *key, *private;
 241         u_char *blob, *data, *signature = NULL;
 242         u_int blen, dlen, slen = 0;
 243         int flags;
 244         Buffer msg;
 245         int ok = -1;
 246
 247         datafellows = 0;
 248
 249         blob = buffer_get_string(&e->input, &blen);
 250         data = buffer_get_string(&e->input, &dlen);
 251
 252         flags = buffer_get_int(&e->input);
 253         if (flags & SSH_AGENT_OLD_SIGNATURE)
 254                 datafellows = SSH_BUG_SIGBLOB;
 255
 256         key = key_from_blob(blob, blen);
 257         if (key != NULL) {
 258                 private = lookup_private_key(key, NULL, 2);
 259                 if (private != NULL)
 260                         ok = key_sign(private, &signature, &slen, data, dlen);
 261         }
 262         key_free(key);
 263         buffer_init(&msg);
 264         if (ok == 0) {
 265                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 266                 buffer_put_string(&msg, signature, slen);
 267         } else {
 268                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 269         }
 270         buffer_put_int(&e->output, buffer_len(&msg));
 271         buffer_append(&e->output, buffer_ptr(&msg),
 272             buffer_len(&msg));
 273         buffer_free(&msg);
 274         xfree(data);
 275         xfree(blob);
 276         if (signature != NULL)
 277                 xfree(signature);
 278 }
 279
 280 /* shared */
 281 void
 282 process_remove_identity(SocketEntry *e, int version)
 283 {
 284         Key *key = NULL, *private;
 285         u_char *blob;
 286         u_int blen;
 287         u_int bits;
 288         int success = 0;
 289
 290         switch(version){
 291         case 1:
 292                 key = key_new(KEY_RSA1);
 293                 bits = buffer_get_int(&e->input);
 294                 buffer_get_bignum(&e->input, key->rsa->e);
 295                 buffer_get_bignum(&e->input, key->rsa->n);
 296
 297                 if (bits != key_size(key))
 298                         log("Warning: identity keysize mismatch: actual %d, announced %d",
 299                             key_size(key), bits);
 300                 break;
 301         case 2:
 302                 blob = buffer_get_string(&e->input, &blen);
 303                 key = key_from_blob(blob, blen);
 304                 xfree(blob);
 305                 break;
 306         }
 307         if (key != NULL) {
 308                 int idx;
 309                 private = lookup_private_key(key, &idx, version);
 310                 if (private != NULL) {
 311                         /*
 312                          * We have this key.  Free the old key.  Since we
 313                          * don\'t want to leave empty slots in the middle of
 314                          * the array, we actually free the key there and move
 315                          * all the entries between the empty slot and the end
 316                          * of the array.
 317                          */
 318                         Idtab *tab = idtab_lookup(version);
 319                         key_free(tab->identities[idx].key);
 320                         xfree(tab->identities[idx].comment);
 321                         if (tab->nentries < 1)
 322                                 fatal("process_remove_identity: "
 323                                     "internal error: tab->nentries %d",
 324                                     tab->nentries);
 325                         if (idx != tab->nentries - 1) {
 326                                 int i;
 327                                 for (i = idx; i < tab->nentries - 1; i++)
 328                                         tab->identities[i] = tab->identities[i+1];
 329                         }
 330                         tab->identities[tab->nentries - 1].key = NULL;
 331                         tab->identities[tab->nentries - 1].comment = NULL;
 332                         tab->nentries--;
 333                         success = 1;
 334                 }
 335                 key_free(key);
 336         }
 337         buffer_put_int(&e->output, 1);
 338         buffer_put_char(&e->output,
 339             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 340 }
 341
 342 void
 343 process_remove_all_identities(SocketEntry *e, int version)
 344 {
 345         u_int i;
 346         Idtab *tab = idtab_lookup(version);
 347
 348         /* Loop over all identities and clear the keys. */
 349         for (i = 0; i < tab->nentries; i++) {
 350                 key_free(tab->identities[i].key);
 351                 xfree(tab->identities[i].comment);
 352         }
 353
 354         /* Mark that there are no identities. */
 355         tab->nentries = 0;
 356
 357         /* Send success. */
 358         buffer_put_int(&e->output, 1);
 359         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 360         return;
 361 }
 362
 363 void
 364 generate_additional_parameters(RSA *rsa)
 365 {
 366         BIGNUM *aux;
 367         BN_CTX *ctx;
 368         /* Generate additional parameters */
 369         aux = BN_new();
 370         ctx = BN_CTX_new();
 371
 372         BN_sub(aux, rsa->q, BN_value_one());
 373         BN_mod(rsa->dmq1, rsa->d, aux, ctx);
 374
 375         BN_sub(aux, rsa->p, BN_value_one());
 376         BN_mod(rsa->dmp1, rsa->d, aux, ctx);
 377
 378         BN_clear_free(aux);
 379         BN_CTX_free(ctx);
 380 }
 381
 382 void
 383 process_add_identity(SocketEntry *e, int version)
 384 {
 385         Key *k = NULL;
 386         char *type_name;
 387         char *comment;
 388         int type, success = 0;
 389         Idtab *tab = idtab_lookup(version);
 390
 391         switch (version) {
 392         case 1:
 393                 k = key_new_private(KEY_RSA1);
 394                 buffer_get_int(&e->input);                      /* ignored */
 395                 buffer_get_bignum(&e->input, k->rsa->n);
 396                 buffer_get_bignum(&e->input, k->rsa->e);
 397                 buffer_get_bignum(&e->input, k->rsa->d);
 398                 buffer_get_bignum(&e->input, k->rsa->iqmp);
 399
 400                 /* SSH and SSL have p and q swapped */
 401                 buffer_get_bignum(&e->input, k->rsa->q);        /* p */
 402                 buffer_get_bignum(&e->input, k->rsa->p);        /* q */
 403
 404                 /* Generate additional parameters */
 405                 generate_additional_parameters(k->rsa);
 406                 break;
 407         case 2:
 408                 type_name = buffer_get_string(&e->input, NULL);
 409                 type = key_type_from_name(type_name);
 410                 xfree(type_name);
 411                 switch(type) {
 412                 case KEY_DSA:
 413                         k = key_new_private(type);
 414                         buffer_get_bignum2(&e->input, k->dsa->p);
 415                         buffer_get_bignum2(&e->input, k->dsa->q);
 416                         buffer_get_bignum2(&e->input, k->dsa->g);
 417                         buffer_get_bignum2(&e->input, k->dsa->pub_key);
 418                         buffer_get_bignum2(&e->input, k->dsa->priv_key);
 419                         break;
 420                 case KEY_RSA:
 421                         k = key_new_private(type);
 422                         buffer_get_bignum2(&e->input, k->rsa->n);
 423                         buffer_get_bignum2(&e->input, k->rsa->e);
 424                         buffer_get_bignum2(&e->input, k->rsa->d);
 425                         buffer_get_bignum2(&e->input, k->rsa->iqmp);
 426                         buffer_get_bignum2(&e->input, k->rsa->p);
 427                         buffer_get_bignum2(&e->input, k->rsa->q);
 428
 429                         /* Generate additional parameters */
 430                         generate_additional_parameters(k->rsa);
 431                         break;
 432                 default:
 433                         buffer_clear(&e->input);
 434                         goto send;
 435                 }
 436                 break;
 437         }
 438         comment = buffer_get_string(&e->input, NULL);
 439         if (k == NULL) {
 440                 xfree(comment);
 441                 goto send;
 442         }
 443         success = 1;
 444         if (lookup_private_key(k, NULL, version) == NULL) {
 445                 if (tab->nentries == 0)
 446                         tab->identities = xmalloc(sizeof(Identity));
 447                 else
 448                         tab->identities = xrealloc(tab->identities,
 449                             (tab->nentries + 1) * sizeof(Identity));
 450                 tab->identities[tab->nentries].key = k;
 451                 tab->identities[tab->nentries].comment = comment;
 452                 /* Increment the number of identities. */
 453                 tab->nentries++;
 454         } else {
 455                 key_free(k);
 456                 xfree(comment);
 457         }
 458 send:
 459         buffer_put_int(&e->output, 1);
 460         buffer_put_char(&e->output,
 461             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 462 }
 463
 464 /* dispatch incoming messages */
 465
 466 void
 467 process_message(SocketEntry *e)
 468 {
 469         u_int msg_len;
 470         u_int type;
 471         u_char *cp;
 472         if (buffer_len(&e->input) < 5)
 473                 return;         /* Incomplete message. */
 474         cp = (u_char *) buffer_ptr(&e->input);
 475         msg_len = GET_32BIT(cp);
 476         if (msg_len > 256 * 1024) {
 477                 shutdown(e->fd, SHUT_RDWR);
 478                 close(e->fd);
 479                 e->type = AUTH_UNUSED;
 480                 return;
 481         }
 482         if (buffer_len(&e->input) < msg_len + 4)
 483                 return;
 484         buffer_consume(&e->input, 4);
 485         type = buffer_get_char(&e->input);
 486
 487         switch (type) {
 488         /* ssh1 */
 489         case SSH_AGENTC_RSA_CHALLENGE:
 490                 process_authentication_challenge1(e);
 491                 break;
 492         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 493                 process_request_identities(e, 1);
 494                 break;
 495         case SSH_AGENTC_ADD_RSA_IDENTITY:
 496                 process_add_identity(e, 1);
 497                 break;
 498         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 499                 process_remove_identity(e, 1);
 500                 break;
 501         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 502                 process_remove_all_identities(e, 1);
 503                 break;
 504         /* ssh2 */
 505         case SSH2_AGENTC_SIGN_REQUEST:
 506                 process_sign_request2(e);
 507                 break;
 508         case SSH2_AGENTC_REQUEST_IDENTITIES:
 509                 process_request_identities(e, 2);
 510                 break;
 511         case SSH2_AGENTC_ADD_IDENTITY:
 512                 process_add_identity(e, 2);
 513                 break;
 514         case SSH2_AGENTC_REMOVE_IDENTITY:
 515                 process_remove_identity(e, 2);
 516                 break;
 517         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 518                 process_remove_all_identities(e, 2);
 519                 break;
 520         default:
 521                 /* Unknown message.  Respond with failure. */
 522                 error("Unknown message %d", type);
 523                 buffer_clear(&e->input);
 524                 buffer_put_int(&e->output, 1);
 525                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 526                 break;
 527         }
 528 }
 529
 530 void
 531 new_socket(int type, int fd)
 532 {
 533         u_int i, old_alloc;
 534         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 535                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 536
 537         if (fd > max_fd)
 538                 max_fd = fd;
 539
 540         for (i = 0; i < sockets_alloc; i++)
 541                 if (sockets[i].type == AUTH_UNUSED) {
 542                         sockets[i].fd = fd;
 543                         sockets[i].type = type;
 544                         buffer_init(&sockets[i].input);
 545                         buffer_init(&sockets[i].output);
 546                         return;
 547                 }
 548         old_alloc = sockets_alloc;
 549         sockets_alloc += 10;
 550         if (sockets)
 551                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 552         else
 553                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 554         for (i = old_alloc; i < sockets_alloc; i++)
 555                 sockets[i].type = AUTH_UNUSED;
 556         sockets[old_alloc].type = type;
 557         sockets[old_alloc].fd = fd;
 558         buffer_init(&sockets[old_alloc].input);
 559         buffer_init(&sockets[old_alloc].output);
 560 }
 561
 562 int
 563 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl)
 564 {
 565         u_int i, sz;
 566         int n = 0;
 567
 568         for (i = 0; i < sockets_alloc; i++) {
 569                 switch (sockets[i].type) {
 570                 case AUTH_SOCKET:
 571                 case AUTH_CONNECTION:
 572                         n = MAX(n, sockets[i].fd);
 573                         break;
 574                 case AUTH_UNUSED:
 575                         break;
 576                 default:
 577                         fatal("Unknown socket type %d", sockets[i].type);
 578                         break;
 579                 }
 580         }
 581
 582         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 583         if (*fdrp == NULL || n > *fdl) {
 584                 if (*fdrp)
 585                         free(*fdrp);
 586                 if (*fdwp)
 587                         free(*fdwp);
 588                 *fdrp = xmalloc(sz);
 589                 *fdwp = xmalloc(sz);
 590                 *fdl = n;
 591         }
 592         memset(*fdrp, 0, sz);
 593         memset(*fdwp, 0, sz);
 594
 595         for (i = 0; i < sockets_alloc; i++) {
 596                 switch (sockets[i].type) {
 597                 case AUTH_SOCKET:
 598                 case AUTH_CONNECTION:
 599                         FD_SET(sockets[i].fd, *fdrp);
 600                         if (buffer_len(&sockets[i].output) > 0)
 601                                 FD_SET(sockets[i].fd, *fdwp);
 602                         break;
 603                 default:
 604                         break;
 605                 }
 606         }
 607         return (1);
 608 }
 609
 610 void
 611 after_select(fd_set *readset, fd_set *writeset)
 612 {
 613         u_int i;
 614         int len, sock;
 615         socklen_t slen;
 616         char buf[1024];
 617         struct sockaddr_un sunaddr;
 618
 619         for (i = 0; i < sockets_alloc; i++)
 620                 switch (sockets[i].type) {
 621                 case AUTH_UNUSED:
 622                         break;
 623                 case AUTH_SOCKET:
 624                         if (FD_ISSET(sockets[i].fd, readset)) {
 625                                 slen = sizeof(sunaddr);
 626                                 sock = accept(sockets[i].fd,
 627                                     (struct sockaddr *) &sunaddr, &slen);
 628                                 if (sock < 0) {
 629                                         perror("accept from AUTH_SOCKET");
 630                                         break;
 631                                 }
 632                                 new_socket(AUTH_CONNECTION, sock);
 633                         }
 634                         break;
 635                 case AUTH_CONNECTION:
 636                         if (buffer_len(&sockets[i].output) > 0 &&
 637                             FD_ISSET(sockets[i].fd, writeset)) {
 638                                 len = write(sockets[i].fd,
 639                                     buffer_ptr(&sockets[i].output),
 640                                     buffer_len(&sockets[i].output));
 641                                 if (len <= 0) {
 642                                         shutdown(sockets[i].fd, SHUT_RDWR);
 643                                         close(sockets[i].fd);
 644                                         sockets[i].type = AUTH_UNUSED;
 645                                         buffer_free(&sockets[i].input);
 646                                         buffer_free(&sockets[i].output);
 647                                         break;
 648                                 }
 649                                 buffer_consume(&sockets[i].output, len);
 650                         }
 651                         if (FD_ISSET(sockets[i].fd, readset)) {
 652                                 len = read(sockets[i].fd, buf, sizeof(buf));
 653                                 if (len <= 0) {
 654                                         shutdown(sockets[i].fd, SHUT_RDWR);
 655                                         close(sockets[i].fd);
 656                                         sockets[i].type = AUTH_UNUSED;
 657                                         buffer_free(&sockets[i].input);
 658                                         buffer_free(&sockets[i].output);
 659                                         break;
 660                                 }
 661                                 buffer_append(&sockets[i].input, buf, len);
 662                                 process_message(&sockets[i]);
 663                         }
 664                         break;
 665                 default:
 666                         fatal("Unknown type %d", sockets[i].type);
 667                 }
 668 }
 669
 670 void
 671 check_parent_exists(int sig)
 672 {
 673         int save_errno = errno;
 674
 675         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 676                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 677                 exit(1);
 678         }
 679         signal(SIGALRM, check_parent_exists);
 680         alarm(10);
 681         errno = save_errno;
 682 }
 683
 684 void
 685 cleanup_socket(void)
 686 {
 687         if (socket_name[0])
 688                 unlink(socket_name);
 689         if (socket_dir[0])
 690                 rmdir(socket_dir);
 691 }
 692
 693 void
 694 cleanup_exit(int i)
 695 {
 696         cleanup_socket();
 697         exit(i);
 698 }
 699
 700 void
 701 cleanup_handler(int sig)
 702 {
 703         cleanup_socket();
 704         _exit(2);
 705 }
 706
 707 void
 708 usage(void)
 709 {
 710         fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION);
 711         fprintf(stderr, "Usage: %s [-c | -s] [-k] [command {args...]]\n",
 712             __progname);
 713         exit(1);
 714 }
 715
 716 int
 717 main(int ac, char **av)
 718 {
 719         int sock, c_flag = 0, k_flag = 0, s_flag = 0, ch;
 720         struct sockaddr_un sunaddr;
 721 #ifdef HAVE_SETRLIMIT
 722         struct rlimit rlim;
 723 #endif
 724         pid_t pid;
 725         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 726         extern int optind;
 727         fd_set *readsetp = NULL, *writesetp = NULL;
 728
 729         __progname = get_progname(av[0]);
 730         init_rng();
 731
 732 #ifdef __GNU_LIBRARY__
 733         while ((ch = getopt(ac, av, "+cks")) != -1) {
 734 #else /* __GNU_LIBRARY__ */
 735         while ((ch = getopt(ac, av, "cks")) != -1) {
 736 #endif /* __GNU_LIBRARY__ */
 737                 switch (ch) {
 738                 case 'c':
 739                         if (s_flag)
 740                                 usage();
 741                         c_flag++;
 742                         break;
 743                 case 'k':
 744                         k_flag++;
 745                         break;
 746                 case 's':
 747                         if (c_flag)
 748                                 usage();
 749                         s_flag++;
 750                         break;
 751                 default:
 752                         usage();
 753                 }
 754         }
 755         ac -= optind;
 756         av += optind;
 757
 758         if (ac > 0 && (c_flag || k_flag || s_flag))
 759                 usage();
 760
 761         if (ac == 0 && !c_flag && !k_flag && !s_flag) {
 762                 shell = getenv("SHELL");
 763                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 764                         c_flag = 1;
 765         }
 766         if (k_flag) {
 767                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 768                 if (pidstr == NULL) {
 769                         fprintf(stderr, "%s not set, cannot kill agent\n",
 770                             SSH_AGENTPID_ENV_NAME);
 771                         exit(1);
 772                 }
 773                 pid = atoi(pidstr);
 774                 if (pid < 1) {
 775                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 776                             SSH_AGENTPID_ENV_NAME, pidstr);
 777                         exit(1);
 778                 }
 779                 if (kill(pid, SIGTERM) == -1) {
 780                         perror("kill");
 781                         exit(1);
 782                 }
 783                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 784                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 785                 printf(format, SSH_AGENTPID_ENV_NAME);
 786                 printf("echo Agent pid %d killed;\n", pid);
 787                 exit(0);
 788         }
 789         parent_pid = getpid();
 790
 791         /* Create private directory for agent socket */
 792         strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 793         if (mkdtemp(socket_dir) == NULL) {
 794                 perror("mkdtemp: private socket dir");
 795                 exit(1);
 796         }
 797         snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 798             parent_pid);
 799
 800         /*
 801          * Create socket early so it will exist before command gets run from
 802          * the parent.
 803          */
 804         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 805         if (sock < 0) {
 806                 perror("socket");
 807                 cleanup_exit(1);
 808         }
 809         memset(&sunaddr, 0, sizeof(sunaddr));
 810         sunaddr.sun_family = AF_UNIX;
 811         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 812         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 813                 perror("bind");
 814                 cleanup_exit(1);
 815         }
 816         if (listen(sock, 5) < 0) {
 817                 perror("listen");
 818                 cleanup_exit(1);
 819         }
 820
 821         /*
 822          * Fork, and have the parent execute the command, if any, or present
 823          * the socket data.  The child continues as the authentication agent.
 824          */
 825         pid = fork();
 826         if (pid == -1) {
 827                 perror("fork");
 828                 exit(1);
 829         }
 830         if (pid != 0) {         /* Parent - execute the given command. */
 831                 close(sock);
 832                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 833                 if (ac == 0) {
 834                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 835                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 836                             SSH_AUTHSOCKET_ENV_NAME);
 837                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 838                             SSH_AGENTPID_ENV_NAME);
 839                         printf("echo Agent pid %d;\n", pid);
 840                         exit(0);
 841                 }
 842                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 843                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 844                         perror("setenv");
 845                         exit(1);
 846                 }
 847                 execvp(av[0], av);
 848                 perror(av[0]);
 849                 exit(1);
 850         }
 851         close(0);
 852         close(1);
 853         close(2);
 854
 855 #ifdef HAVE_SETRLIMIT
 856         /* deny core dumps, since memory contains unencrypted private keys */
 857         rlim.rlim_cur = rlim.rlim_max = 0;
 858         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
 859                 perror("setrlimit rlimit_core failed");
 860                 cleanup_exit(1);
 861         }
 862 #endif
 863         if (setsid() == -1) {
 864                 perror("setsid");
 865                 cleanup_exit(1);
 866         }
 867         if (atexit(cleanup_socket) < 0) {
 868                 perror("atexit");
 869                 cleanup_exit(1);
 870         }
 871         new_socket(AUTH_SOCKET, sock);
 872         if (ac > 0) {
 873                 signal(SIGALRM, check_parent_exists);
 874                 alarm(10);
 875         }
 876         idtab_init();
 877         signal(SIGINT, SIG_IGN);
 878         signal(SIGPIPE, SIG_IGN);
 879         signal(SIGHUP, cleanup_handler);
 880         signal(SIGTERM, cleanup_handler);
 881         while (1) {
 882                 prepare_select(&readsetp, &writesetp, &max_fd);
 883                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
 884                         if (errno == EINTR)
 885                                 continue;
 886                         exit(1);
 887                 }
 888                 after_select(readsetp, writesetp);
 889         }
 890         /* NOTREACHED */
 891 }