ssh-agent.c

   1 /*      $OpenBSD: ssh-agent.c,v 1.37 2000/09/21 11:07:51 markus 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 1.37 2000/09/21 11:07:51 markus Exp $");
  41
  42 #include "ssh.h"
  43 #include "rsa.h"
  44 #include "buffer.h"
  45 #include "bufaux.h"
  46 #include "xmalloc.h"
  47 #include "packet.h"
  48 #include "getput.h"
  49 #include "mpaux.h"
  50
  51 #include <openssl/evp.h>
  52 #include <openssl/md5.h>
  53 #include <openssl/dsa.h>
  54 #include <openssl/rsa.h>
  55 #include "key.h"
  56 #include "authfd.h"
  57 #include "dsa.h"
  58 #include "kex.h"
  59 #include "compat.h"
  60
  61 typedef struct {
  62         int fd;
  63         enum {
  64                 AUTH_UNUSED, AUTH_SOCKET, AUTH_CONNECTION
  65         } type;
  66         Buffer input;
  67         Buffer output;
  68 } SocketEntry;
  69
  70 unsigned int sockets_alloc = 0;
  71 SocketEntry *sockets = NULL;
  72
  73 typedef struct {
  74         Key *key;
  75         char *comment;
  76 } Identity;
  77
  78 typedef struct {
  79         int nentries;
  80         Identity *identities;
  81 } Idtab;
  82
  83 /* private key table, one per protocol version */
  84 Idtab idtable[3];
  85
  86 int max_fd = 0;
  87
  88 /* pid of shell == parent of agent */
  89 pid_t parent_pid = -1;
  90
  91 /* pathname and directory for AUTH_SOCKET */
  92 char socket_name[1024];
  93 char socket_dir[1024];
  94
  95 #ifdef HAVE___PROGNAME
  96 extern char *__progname;
  97 #else /* HAVE___PROGNAME */
  98 static const char *__progname = "ssh-agent";
  99 #endif /* HAVE___PROGNAME */
 100
 101 void
 102 idtab_init(void)
 103 {
 104         int i;
 105         for (i = 0; i <=2; i++){
 106                 idtable[i].identities = NULL;
 107                 idtable[i].nentries = 0;
 108         }
 109 }
 110
 111 /* return private key table for requested protocol version */
 112 Idtab *
 113 idtab_lookup(int version)
 114 {
 115         if (version < 1 || version > 2)
 116                 fatal("internal error, bad protocol version %d", version);
 117         return &idtable[version];
 118 }
 119
 120 /* return matching private key for given public key */
 121 Key *
 122 lookup_private_key(Key *key, int *idx, int version)
 123 {
 124         int i;
 125         Idtab *tab = idtab_lookup(version);
 126         for (i = 0; i < tab->nentries; i++) {
 127                 if (key_equal(key, tab->identities[i].key)) {
 128                         if (idx != NULL)
 129                                 *idx = i;
 130                         return tab->identities[i].key;
 131                 }
 132         }
 133         return NULL;
 134 }
 135
 136 /* send list of supported public keys to 'client' */
 137 void
 138 process_request_identities(SocketEntry *e, int version)
 139 {
 140         Idtab *tab = idtab_lookup(version);
 141         Buffer msg;
 142         int i;
 143
 144         buffer_init(&msg);
 145         buffer_put_char(&msg, (version == 1) ?
 146             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 147         buffer_put_int(&msg, tab->nentries);
 148         for (i = 0; i < tab->nentries; i++) {
 149                 Identity *id = &tab->identities[i];
 150                 if (id->key->type == KEY_RSA) {
 151                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 152                         buffer_put_bignum(&msg, id->key->rsa->e);
 153                         buffer_put_bignum(&msg, id->key->rsa->n);
 154                 } else {
 155                         unsigned char *blob;
 156                         unsigned int blen;
 157                         dsa_make_key_blob(id->key, &blob, &blen);
 158                         buffer_put_string(&msg, blob, blen);
 159                         xfree(blob);
 160                 }
 161                 buffer_put_cstring(&msg, id->comment);
 162         }
 163         buffer_put_int(&e->output, buffer_len(&msg));
 164         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 165         buffer_free(&msg);
 166 }
 167
 168 /* ssh1 only */
 169 void
 170 process_authentication_challenge1(SocketEntry *e)
 171 {
 172         Key *key, *private;
 173         BIGNUM *challenge;
 174         int i, len;
 175         Buffer msg;
 176         MD5_CTX md;
 177         unsigned char buf[32], mdbuf[16], session_id[16];
 178         unsigned int response_type;
 179
 180         buffer_init(&msg);
 181         key = key_new(KEY_RSA);
 182         challenge = BN_new();
 183
 184         buffer_get_int(&e->input);                              /* ignored */
 185         buffer_get_bignum(&e->input, key->rsa->e);
 186         buffer_get_bignum(&e->input, key->rsa->n);
 187         buffer_get_bignum(&e->input, challenge);
 188
 189         /* Only protocol 1.1 is supported */
 190         if (buffer_len(&e->input) == 0)
 191                 goto failure;
 192         buffer_get(&e->input, (char *) session_id, 16);
 193         response_type = buffer_get_int(&e->input);
 194         if (response_type != 1)
 195                 goto failure;
 196
 197         private = lookup_private_key(key, NULL, 1);
 198         if (private != NULL) {
 199                 /* Decrypt the challenge using the private key. */
 200                 rsa_private_decrypt(challenge, challenge, private->rsa);
 201
 202                 /* The response is MD5 of decrypted challenge plus session id. */
 203                 len = BN_num_bytes(challenge);
 204                 if (len <= 0 || len > 32) {
 205                         log("process_authentication_challenge: bad challenge length %d", len);
 206                         goto failure;
 207                 }
 208                 memset(buf, 0, 32);
 209                 BN_bn2bin(challenge, buf + 32 - len);
 210                 MD5_Init(&md);
 211                 MD5_Update(&md, buf, 32);
 212                 MD5_Update(&md, session_id, 16);
 213                 MD5_Final(mdbuf, &md);
 214
 215                 /* Send the response. */
 216                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 217                 for (i = 0; i < 16; i++)
 218                         buffer_put_char(&msg, mdbuf[i]);
 219                 goto send;
 220         }
 221
 222 failure:
 223         /* Unknown identity or protocol error.  Send failure. */
 224         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 225 send:
 226         buffer_put_int(&e->output, buffer_len(&msg));
 227         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 228         key_free(key);
 229         BN_clear_free(challenge);
 230         buffer_free(&msg);
 231 }
 232
 233 /* ssh2 only */
 234 void
 235 process_sign_request2(SocketEntry *e)
 236 {
 237         extern int datafellows;
 238         Key *key, *private;
 239         unsigned char *blob, *data, *signature = NULL;
 240         unsigned int blen, dlen, slen = 0;
 241         int flags;
 242         Buffer msg;
 243         int ok = -1;
 244
 245         datafellows = 0;
 246
 247         blob = buffer_get_string(&e->input, &blen);
 248         data = buffer_get_string(&e->input, &dlen);
 249
 250         flags = buffer_get_int(&e->input);
 251         if (flags & SSH_AGENT_OLD_SIGNATURE)
 252                 datafellows = SSH_BUG_SIGBLOB;
 253
 254         key = dsa_key_from_blob(blob, blen);
 255         if (key != NULL) {
 256                 private = lookup_private_key(key, NULL, 2);
 257                 if (private != NULL)
 258                         ok = dsa_sign(private, &signature, &slen, data, dlen);
 259         }
 260         key_free(key);
 261         buffer_init(&msg);
 262         if (ok == 0) {
 263                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 264                 buffer_put_string(&msg, signature, slen);
 265         } else {
 266                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 267         }
 268         buffer_put_int(&e->output, buffer_len(&msg));
 269         buffer_append(&e->output, buffer_ptr(&msg),
 270             buffer_len(&msg));
 271         buffer_free(&msg);
 272         xfree(data);
 273         xfree(blob);
 274         if (signature != NULL)
 275                 xfree(signature);
 276 }
 277
 278 /* shared */
 279 void
 280 process_remove_identity(SocketEntry *e, int version)
 281 {
 282         Key *key = NULL, *private;
 283         unsigned char *blob;
 284         unsigned int blen;
 285         unsigned int bits;
 286         int success = 0;
 287
 288         switch(version){
 289         case 1:
 290                 key = key_new(KEY_RSA);
 291                 bits = buffer_get_int(&e->input);
 292                 buffer_get_bignum(&e->input, key->rsa->e);
 293                 buffer_get_bignum(&e->input, key->rsa->n);
 294
 295                 if (bits != key_size(key))
 296                         log("Warning: identity keysize mismatch: actual %d, announced %d",
 297                               key_size(key), bits);
 298                 break;
 299         case 2:
 300                 blob = buffer_get_string(&e->input, &blen);
 301                 key = dsa_key_from_blob(blob, blen);
 302                 xfree(blob);
 303                 break;
 304         }
 305         if (key != NULL) {
 306                 int idx;
 307                 private = lookup_private_key(key, &idx, version);
 308                 if (private != NULL) {
 309                         /*
 310                          * We have this key.  Free the old key.  Since we
 311                          * don\'t want to leave empty slots in the middle of
 312                          * the array, we actually free the key there and copy
 313                          * data from the last entry.
 314                          */
 315                         Idtab *tab = idtab_lookup(version);
 316                         key_free(tab->identities[idx].key);
 317                         xfree(tab->identities[idx].comment);
 318                         if (idx != tab->nentries)
 319                                 tab->identities[idx] = tab->identities[tab->nentries];
 320                         tab->nentries--;
 321                         success = 1;
 322                 }
 323                 key_free(key);
 324         }
 325         buffer_put_int(&e->output, 1);
 326         buffer_put_char(&e->output,
 327             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 328 }
 329
 330 void
 331 process_remove_all_identities(SocketEntry *e, int version)
 332 {
 333         unsigned int i;
 334         Idtab *tab = idtab_lookup(version);
 335
 336         /* Loop over all identities and clear the keys. */
 337         for (i = 0; i < tab->nentries; i++) {
 338                 key_free(tab->identities[i].key);
 339                 xfree(tab->identities[i].comment);
 340         }
 341
 342         /* Mark that there are no identities. */
 343         tab->nentries = 0;
 344
 345         /* Send success. */
 346         buffer_put_int(&e->output, 1);
 347         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 348         return;
 349 }
 350
 351 void
 352 process_add_identity(SocketEntry *e, int version)
 353 {
 354         Key *k = NULL;
 355         RSA *rsa;
 356         BIGNUM *aux;
 357         BN_CTX *ctx;
 358         char *type;
 359         char *comment;
 360         int success = 0;
 361         Idtab *tab = idtab_lookup(version);
 362
 363         switch (version) {
 364         case 1:
 365                 k = key_new(KEY_RSA);
 366                 rsa = k->rsa;
 367
 368                 /* allocate mem for private key */
 369                 /* XXX rsa->n and rsa->e are already allocated */
 370                 rsa->d = BN_new();
 371                 rsa->iqmp = BN_new();
 372                 rsa->q = BN_new();
 373                 rsa->p = BN_new();
 374                 rsa->dmq1 = BN_new();
 375                 rsa->dmp1 = BN_new();
 376
 377                 buffer_get_int(&e->input);               /* ignored */
 378
 379                 buffer_get_bignum(&e->input, rsa->n);
 380                 buffer_get_bignum(&e->input, rsa->e);
 381                 buffer_get_bignum(&e->input, rsa->d);
 382                 buffer_get_bignum(&e->input, rsa->iqmp);
 383
 384                 /* SSH and SSL have p and q swapped */
 385                 buffer_get_bignum(&e->input, rsa->q);   /* p */
 386                 buffer_get_bignum(&e->input, rsa->p);   /* q */
 387
 388                 /* Generate additional parameters */
 389                 aux = BN_new();
 390                 ctx = BN_CTX_new();
 391
 392                 BN_sub(aux, rsa->q, BN_value_one());
 393                 BN_mod(rsa->dmq1, rsa->d, aux, ctx);
 394
 395                 BN_sub(aux, rsa->p, BN_value_one());
 396                 BN_mod(rsa->dmp1, rsa->d, aux, ctx);
 397
 398                 BN_clear_free(aux);
 399                 BN_CTX_free(ctx);
 400
 401                 break;
 402         case 2:
 403                 type = buffer_get_string(&e->input, NULL);
 404                 if (strcmp(type, KEX_DSS)) {
 405                         buffer_clear(&e->input);
 406                         xfree(type);
 407                         goto send;
 408                 }
 409                 xfree(type);
 410
 411                 k = key_new(KEY_DSA);
 412
 413                 /* allocate mem for private key */
 414                 k->dsa->priv_key = BN_new();
 415
 416                 buffer_get_bignum2(&e->input, k->dsa->p);
 417                 buffer_get_bignum2(&e->input, k->dsa->q);
 418                 buffer_get_bignum2(&e->input, k->dsa->g);
 419                 buffer_get_bignum2(&e->input, k->dsa->pub_key);
 420                 buffer_get_bignum2(&e->input, k->dsa->priv_key);
 421
 422                 break;
 423         }
 424
 425         comment = buffer_get_string(&e->input, NULL);
 426         if (k == NULL) {
 427                 xfree(comment);
 428                 goto send;
 429         }
 430         success = 1;
 431         if (lookup_private_key(k, NULL, version) == NULL) {
 432                 if (tab->nentries == 0)
 433                         tab->identities = xmalloc(sizeof(Identity));
 434                 else
 435                         tab->identities = xrealloc(tab->identities,
 436                             (tab->nentries + 1) * sizeof(Identity));
 437                 tab->identities[tab->nentries].key = k;
 438                 tab->identities[tab->nentries].comment = comment;
 439                 /* Increment the number of identities. */
 440                 tab->nentries++;
 441         } else {
 442                 key_free(k);
 443                 xfree(comment);
 444         }
 445 send:
 446         buffer_put_int(&e->output, 1);
 447         buffer_put_char(&e->output,
 448             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 449 }
 450
 451 /* dispatch incoming messages */
 452
 453 void
 454 process_message(SocketEntry *e)
 455 {
 456         unsigned int msg_len;
 457         unsigned int type;
 458         unsigned char *cp;
 459         if (buffer_len(&e->input) < 5)
 460                 return;         /* Incomplete message. */
 461         cp = (unsigned char *) buffer_ptr(&e->input);
 462         msg_len = GET_32BIT(cp);
 463         if (msg_len > 256 * 1024) {
 464                 shutdown(e->fd, SHUT_RDWR);
 465                 close(e->fd);
 466                 e->type = AUTH_UNUSED;
 467                 return;
 468         }
 469         if (buffer_len(&e->input) < msg_len + 4)
 470                 return;
 471         buffer_consume(&e->input, 4);
 472         type = buffer_get_char(&e->input);
 473
 474         switch (type) {
 475         /* ssh1 */
 476         case SSH_AGENTC_RSA_CHALLENGE:
 477                 process_authentication_challenge1(e);
 478                 break;
 479         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 480                 process_request_identities(e, 1);
 481                 break;
 482         case SSH_AGENTC_ADD_RSA_IDENTITY:
 483                 process_add_identity(e, 1);
 484                 break;
 485         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 486                 process_remove_identity(e, 1);
 487                 break;
 488         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 489                 process_remove_all_identities(e, 1);
 490                 break;
 491         /* ssh2 */
 492         case SSH2_AGENTC_SIGN_REQUEST:
 493                 process_sign_request2(e);
 494                 break;
 495         case SSH2_AGENTC_REQUEST_IDENTITIES:
 496                 process_request_identities(e, 2);
 497                 break;
 498         case SSH2_AGENTC_ADD_IDENTITY:
 499                 process_add_identity(e, 2);
 500                 break;
 501         case SSH2_AGENTC_REMOVE_IDENTITY:
 502                 process_remove_identity(e, 2);
 503                 break;
 504         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 505                 process_remove_all_identities(e, 2);
 506                 break;
 507         default:
 508                 /* Unknown message.  Respond with failure. */
 509                 error("Unknown message %d", type);
 510                 buffer_clear(&e->input);
 511                 buffer_put_int(&e->output, 1);
 512                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 513                 break;
 514         }
 515 }
 516
 517 void
 518 new_socket(int type, int fd)
 519 {
 520         unsigned int i, old_alloc;
 521         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 522                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 523
 524         if (fd > max_fd)
 525                 max_fd = fd;
 526
 527         for (i = 0; i < sockets_alloc; i++)
 528                 if (sockets[i].type == AUTH_UNUSED) {
 529                         sockets[i].fd = fd;
 530                         sockets[i].type = type;
 531                         buffer_init(&sockets[i].input);
 532                         buffer_init(&sockets[i].output);
 533                         return;
 534                 }
 535         old_alloc = sockets_alloc;
 536         sockets_alloc += 10;
 537         if (sockets)
 538                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 539         else
 540                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 541         for (i = old_alloc; i < sockets_alloc; i++)
 542                 sockets[i].type = AUTH_UNUSED;
 543         sockets[old_alloc].type = type;
 544         sockets[old_alloc].fd = fd;
 545         buffer_init(&sockets[old_alloc].input);
 546         buffer_init(&sockets[old_alloc].output);
 547 }
 548
 549 void
 550 prepare_select(fd_set *readset, fd_set *writeset)
 551 {
 552         unsigned int i;
 553         for (i = 0; i < sockets_alloc; i++)
 554                 switch (sockets[i].type) {
 555                 case AUTH_SOCKET:
 556                 case AUTH_CONNECTION:
 557                         FD_SET(sockets[i].fd, readset);
 558                         if (buffer_len(&sockets[i].output) > 0)
 559                                 FD_SET(sockets[i].fd, writeset);
 560                         break;
 561                 case AUTH_UNUSED:
 562                         break;
 563                 default:
 564                         fatal("Unknown socket type %d", sockets[i].type);
 565                         break;
 566                 }
 567 }
 568
 569 void
 570 after_select(fd_set *readset, fd_set *writeset)
 571 {
 572         unsigned int i;
 573         int len, sock;
 574         socklen_t slen;
 575         char buf[1024];
 576         struct sockaddr_un sunaddr;
 577
 578         for (i = 0; i < sockets_alloc; i++)
 579                 switch (sockets[i].type) {
 580                 case AUTH_UNUSED:
 581                         break;
 582                 case AUTH_SOCKET:
 583                         if (FD_ISSET(sockets[i].fd, readset)) {
 584                                 slen = sizeof(sunaddr);
 585                                 sock = accept(sockets[i].fd, (struct sockaddr *) & sunaddr, &slen);
 586                                 if (sock < 0) {
 587                                         perror("accept from AUTH_SOCKET");
 588                                         break;
 589                                 }
 590                                 new_socket(AUTH_CONNECTION, sock);
 591                         }
 592                         break;
 593                 case AUTH_CONNECTION:
 594                         if (buffer_len(&sockets[i].output) > 0 &&
 595                             FD_ISSET(sockets[i].fd, writeset)) {
 596                                 len = write(sockets[i].fd, buffer_ptr(&sockets[i].output),
 597                                          buffer_len(&sockets[i].output));
 598                                 if (len <= 0) {
 599                                         shutdown(sockets[i].fd, SHUT_RDWR);
 600                                         close(sockets[i].fd);
 601                                         sockets[i].type = AUTH_UNUSED;
 602                                         buffer_free(&sockets[i].input);
 603                                         buffer_free(&sockets[i].output);
 604                                         break;
 605                                 }
 606                                 buffer_consume(&sockets[i].output, len);
 607                         }
 608                         if (FD_ISSET(sockets[i].fd, readset)) {
 609                                 len = read(sockets[i].fd, buf, sizeof(buf));
 610                                 if (len <= 0) {
 611                                         shutdown(sockets[i].fd, SHUT_RDWR);
 612                                         close(sockets[i].fd);
 613                                         sockets[i].type = AUTH_UNUSED;
 614                                         buffer_free(&sockets[i].input);
 615                                         buffer_free(&sockets[i].output);
 616                                         break;
 617                                 }
 618                                 buffer_append(&sockets[i].input, buf, len);
 619                                 process_message(&sockets[i]);
 620                         }
 621                         break;
 622                 default:
 623                         fatal("Unknown type %d", sockets[i].type);
 624                 }
 625 }
 626
 627 void
 628 check_parent_exists(int sig)
 629 {
 630         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 631                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 632                 exit(1);
 633         }
 634         signal(SIGALRM, check_parent_exists);
 635         alarm(10);
 636 }
 637
 638 void
 639 cleanup_socket(void)
 640 {
 641         unlink(socket_name);
 642         rmdir(socket_dir);
 643 }
 644
 645 void
 646 cleanup_exit(int i)
 647 {
 648         cleanup_socket();
 649         exit(i);
 650 }
 651
 652 void
 653 usage()
 654 {
 655         fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION);
 656         fprintf(stderr, "Usage: %s [-c | -s] [-k] [command {args...]]\n",
 657                 __progname);
 658         exit(1);
 659 }
 660
 661 int
 662 main(int ac, char **av)
 663 {
 664         fd_set readset, writeset;
 665         int sock, c_flag = 0, k_flag = 0, s_flag = 0, ch;
 666         struct sockaddr_un sunaddr;
 667         pid_t pid;
 668         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 669         extern int optind;
 670
 671         init_rng();
 672
 673         /* check if RSA support exists */
 674         if (rsa_alive() == 0) {
 675                 fprintf(stderr,
 676                         "%s: no RSA support in libssl and libcrypto.  See ssl(8).\n",
 677                         __progname);
 678                 exit(1);
 679         }
 680 #ifdef __GNU_LIBRARY__
 681         while ((ch = getopt(ac, av, "+cks")) != -1) {
 682 #else /* __GNU_LIBRARY__ */
 683         while ((ch = getopt(ac, av, "cks")) != -1) {
 684 #endif /* __GNU_LIBRARY__ */
 685                 switch (ch) {
 686                 case 'c':
 687                         if (s_flag)
 688                                 usage();
 689                         c_flag++;
 690                         break;
 691                 case 'k':
 692                         k_flag++;
 693                         break;
 694                 case 's':
 695                         if (c_flag)
 696                                 usage();
 697                         s_flag++;
 698                         break;
 699                 default:
 700                         usage();
 701                 }
 702         }
 703         ac -= optind;
 704         av += optind;
 705
 706         if (ac > 0 && (c_flag || k_flag || s_flag))
 707                 usage();
 708
 709         if (ac == 0 && !c_flag && !k_flag && !s_flag) {
 710                 shell = getenv("SHELL");
 711                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 712                         c_flag = 1;
 713         }
 714         if (k_flag) {
 715                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 716                 if (pidstr == NULL) {
 717                         fprintf(stderr, "%s not set, cannot kill agent\n",
 718                                 SSH_AGENTPID_ENV_NAME);
 719                         exit(1);
 720                 }
 721                 pid = atoi(pidstr);
 722                 if (pid < 1) {  /* XXX PID_MAX check too */
 723                 /* Yes, PID_MAX check please */
 724                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 725                                 SSH_AGENTPID_ENV_NAME, pidstr);
 726                         exit(1);
 727                 }
 728                 if (kill(pid, SIGTERM) == -1) {
 729                         perror("kill");
 730                         exit(1);
 731                 }
 732                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 733                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 734                 printf(format, SSH_AGENTPID_ENV_NAME);
 735                 printf("echo Agent pid %d killed;\n", pid);
 736                 exit(0);
 737         }
 738         parent_pid = getpid();
 739
 740         /* Create private directory for agent socket */
 741         strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 742         if (mkdtemp(socket_dir) == NULL) {
 743                 perror("mkdtemp: private socket dir");
 744                 exit(1);
 745         }
 746         snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 747                  parent_pid);
 748
 749         /*
 750          * Create socket early so it will exist before command gets run from
 751          * the parent.
 752          */
 753         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 754         if (sock < 0) {
 755                 perror("socket");
 756                 cleanup_exit(1);
 757         }
 758         memset(&sunaddr, 0, sizeof(sunaddr));
 759         sunaddr.sun_family = AF_UNIX;
 760         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 761         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 762                 perror("bind");
 763                 cleanup_exit(1);
 764         }
 765         if (listen(sock, 5) < 0) {
 766                 perror("listen");
 767                 cleanup_exit(1);
 768         }
 769         /*
 770          * Fork, and have the parent execute the command, if any, or present
 771          * the socket data.  The child continues as the authentication agent.
 772          */
 773         pid = fork();
 774         if (pid == -1) {
 775                 perror("fork");
 776                 exit(1);
 777         }
 778         if (pid != 0) {         /* Parent - execute the given command. */
 779                 close(sock);
 780                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 781                 if (ac == 0) {
 782                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 783                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 784                                SSH_AUTHSOCKET_ENV_NAME);
 785                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 786                                SSH_AGENTPID_ENV_NAME);
 787                         printf("echo Agent pid %d;\n", pid);
 788                         exit(0);
 789                 }
 790                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 791                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 792                         perror("setenv");
 793                         exit(1);
 794                 }
 795                 execvp(av[0], av);
 796                 perror(av[0]);
 797                 exit(1);
 798         }
 799         close(0);
 800         close(1);
 801         close(2);
 802
 803         if (setsid() == -1) {
 804                 perror("setsid");
 805                 cleanup_exit(1);
 806         }
 807         if (atexit(cleanup_socket) < 0) {
 808                 perror("atexit");
 809                 cleanup_exit(1);
 810         }
 811         new_socket(AUTH_SOCKET, sock);
 812         if (ac > 0) {
 813                 signal(SIGALRM, check_parent_exists);
 814                 alarm(10);
 815         }
 816         idtab_init();
 817         signal(SIGINT, SIG_IGN);
 818         signal(SIGPIPE, SIG_IGN);
 819         signal(SIGHUP, cleanup_exit);
 820         signal(SIGTERM, cleanup_exit);
 821         while (1) {
 822                 FD_ZERO(&readset);
 823                 FD_ZERO(&writeset);
 824                 prepare_select(&readset, &writeset);
 825                 if (select(max_fd + 1, &readset, &writeset, NULL, NULL) < 0) {
 826                         if (errno == EINTR)
 827                                 continue;
 828                         exit(1);
 829                 }
 830                 after_select(&readset, &writeset);
 831         }
 832         /* NOTREACHED */
 833 }