ssh-agent.c

   1 /*      $OpenBSD: ssh-agent.c,v 1.41 2000/11/30 18:33:05 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 1.41 2000/11/30 18:33:05 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 "kex.h"
  58 #include "compat.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 unsigned 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 void
 101 idtab_init(void)
 102 {
 103         int i;
 104         for (i = 0; i <=2; i++){
 105                 idtable[i].identities = NULL;
 106                 idtable[i].nentries = 0;
 107         }
 108 }
 109
 110 /* return private key table for requested protocol version */
 111 Idtab *
 112 idtab_lookup(int version)
 113 {
 114         if (version < 1 || version > 2)
 115                 fatal("internal error, bad protocol version %d", version);
 116         return &idtable[version];
 117 }
 118
 119 /* return matching private key for given public key */
 120 Key *
 121 lookup_private_key(Key *key, int *idx, int version)
 122 {
 123         int i;
 124         Idtab *tab = idtab_lookup(version);
 125         for (i = 0; i < tab->nentries; i++) {
 126                 if (key_equal(key, tab->identities[i].key)) {
 127                         if (idx != NULL)
 128                                 *idx = i;
 129                         return tab->identities[i].key;
 130                 }
 131         }
 132         return NULL;
 133 }
 134
 135 /* send list of supported public keys to 'client' */
 136 void
 137 process_request_identities(SocketEntry *e, int version)
 138 {
 139         Idtab *tab = idtab_lookup(version);
 140         Buffer msg;
 141         int i;
 142
 143         buffer_init(&msg);
 144         buffer_put_char(&msg, (version == 1) ?
 145             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 146         buffer_put_int(&msg, tab->nentries);
 147         for (i = 0; i < tab->nentries; i++) {
 148                 Identity *id = &tab->identities[i];
 149                 if (id->key->type == KEY_RSA1) {
 150                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 151                         buffer_put_bignum(&msg, id->key->rsa->e);
 152                         buffer_put_bignum(&msg, id->key->rsa->n);
 153                 } else {
 154                         unsigned char *blob;
 155                         unsigned int blen;
 156                         key_to_blob(id->key, &blob, &blen);
 157                         buffer_put_string(&msg, blob, blen);
 158                         xfree(blob);
 159                 }
 160                 buffer_put_cstring(&msg, id->comment);
 161         }
 162         buffer_put_int(&e->output, buffer_len(&msg));
 163         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 164         buffer_free(&msg);
 165 }
 166
 167 /* ssh1 only */
 168 void
 169 process_authentication_challenge1(SocketEntry *e)
 170 {
 171         Key *key, *private;
 172         BIGNUM *challenge;
 173         int i, len;
 174         Buffer msg;
 175         MD5_CTX md;
 176         unsigned char buf[32], mdbuf[16], session_id[16];
 177         unsigned int response_type;
 178
 179         buffer_init(&msg);
 180         key = key_new(KEY_RSA1);
 181         challenge = BN_new();
 182
 183         buffer_get_int(&e->input);                              /* ignored */
 184         buffer_get_bignum(&e->input, key->rsa->e);
 185         buffer_get_bignum(&e->input, key->rsa->n);
 186         buffer_get_bignum(&e->input, challenge);
 187
 188         /* Only protocol 1.1 is supported */
 189         if (buffer_len(&e->input) == 0)
 190                 goto failure;
 191         buffer_get(&e->input, (char *) session_id, 16);
 192         response_type = buffer_get_int(&e->input);
 193         if (response_type != 1)
 194                 goto failure;
 195
 196         private = lookup_private_key(key, NULL, 1);
 197         if (private != NULL) {
 198                 /* Decrypt the challenge using the private key. */
 199                 rsa_private_decrypt(challenge, challenge, private->rsa);
 200
 201                 /* The response is MD5 of decrypted challenge plus session id. */
 202                 len = BN_num_bytes(challenge);
 203                 if (len <= 0 || len > 32) {
 204                         log("process_authentication_challenge: bad challenge length %d", len);
 205                         goto failure;
 206                 }
 207                 memset(buf, 0, 32);
 208                 BN_bn2bin(challenge, buf + 32 - len);
 209                 MD5_Init(&md);
 210                 MD5_Update(&md, buf, 32);
 211                 MD5_Update(&md, session_id, 16);
 212                 MD5_Final(mdbuf, &md);
 213
 214                 /* Send the response. */
 215                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 216                 for (i = 0; i < 16; i++)
 217                         buffer_put_char(&msg, mdbuf[i]);
 218                 goto send;
 219         }
 220
 221 failure:
 222         /* Unknown identity or protocol error.  Send failure. */
 223         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 224 send:
 225         buffer_put_int(&e->output, buffer_len(&msg));
 226         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 227         key_free(key);
 228         BN_clear_free(challenge);
 229         buffer_free(&msg);
 230 }
 231
 232 /* ssh2 only */
 233 void
 234 process_sign_request2(SocketEntry *e)
 235 {
 236         extern int datafellows;
 237         Key *key, *private;
 238         unsigned char *blob, *data, *signature = NULL;
 239         unsigned int blen, dlen, slen = 0;
 240         int flags;
 241         Buffer msg;
 242         int ok = -1;
 243
 244         datafellows = 0;
 245
 246         blob = buffer_get_string(&e->input, &blen);
 247         data = buffer_get_string(&e->input, &dlen);
 248
 249         flags = buffer_get_int(&e->input);
 250         if (flags & SSH_AGENT_OLD_SIGNATURE)
 251                 datafellows = SSH_BUG_SIGBLOB;
 252
 253         key = key_from_blob(blob, blen);
 254         if (key != NULL) {
 255                 private = lookup_private_key(key, NULL, 2);
 256                 if (private != NULL)
 257                         ok = key_sign(private, &signature, &slen, data, dlen);
 258         }
 259         key_free(key);
 260         buffer_init(&msg);
 261         if (ok == 0) {
 262                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 263                 buffer_put_string(&msg, signature, slen);
 264         } else {
 265                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 266         }
 267         buffer_put_int(&e->output, buffer_len(&msg));
 268         buffer_append(&e->output, buffer_ptr(&msg),
 269             buffer_len(&msg));
 270         buffer_free(&msg);
 271         xfree(data);
 272         xfree(blob);
 273         if (signature != NULL)
 274                 xfree(signature);
 275 }
 276
 277 /* shared */
 278 void
 279 process_remove_identity(SocketEntry *e, int version)
 280 {
 281         Key *key = NULL, *private;
 282         unsigned char *blob;
 283         unsigned int blen;
 284         unsigned int bits;
 285         int success = 0;
 286
 287         switch(version){
 288         case 1:
 289                 key = key_new(KEY_RSA1);
 290                 bits = buffer_get_int(&e->input);
 291                 buffer_get_bignum(&e->input, key->rsa->e);
 292                 buffer_get_bignum(&e->input, key->rsa->n);
 293
 294                 if (bits != key_size(key))
 295                         log("Warning: identity keysize mismatch: actual %d, announced %d",
 296                               key_size(key), bits);
 297                 break;
 298         case 2:
 299                 blob = buffer_get_string(&e->input, &blen);
 300                 key = key_from_blob(blob, blen);
 301                 xfree(blob);
 302                 break;
 303         }
 304         if (key != NULL) {
 305                 int idx;
 306                 private = lookup_private_key(key, &idx, version);
 307                 if (private != NULL) {
 308                         /*
 309                          * We have this key.  Free the old key.  Since we
 310                          * don\'t want to leave empty slots in the middle of
 311                          * the array, we actually free the key there and move
 312                          * all the entries between the empty slot and the end
 313                          * of the array.
 314                          */
 315                         Idtab *tab = idtab_lookup(version);
 316                         key_free(tab->identities[idx].key);
 317                         xfree(tab->identities[idx].comment);
 318                         if (tab->nentries < 1)
 319                                 fatal("process_remove_identity: "
 320                                     "internal error: tab->nentries %d",
 321                                     tab->nentries);
 322                         if (idx != tab->nentries - 1) {
 323                                 int i;
 324                                 for (i = idx; i < tab->nentries - 1; i++)
 325                                         tab->identities[i] = tab->identities[i+1];
 326                         }
 327                         tab->identities[tab->nentries - 1].key = NULL;
 328                         tab->identities[tab->nentries - 1].comment = NULL;
 329                         tab->nentries--;
 330                         success = 1;
 331                 }
 332                 key_free(key);
 333         }
 334         buffer_put_int(&e->output, 1);
 335         buffer_put_char(&e->output,
 336             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 337 }
 338
 339 void
 340 process_remove_all_identities(SocketEntry *e, int version)
 341 {
 342         unsigned int i;
 343         Idtab *tab = idtab_lookup(version);
 344
 345         /* Loop over all identities and clear the keys. */
 346         for (i = 0; i < tab->nentries; i++) {
 347                 key_free(tab->identities[i].key);
 348                 xfree(tab->identities[i].comment);
 349         }
 350
 351         /* Mark that there are no identities. */
 352         tab->nentries = 0;
 353
 354         /* Send success. */
 355         buffer_put_int(&e->output, 1);
 356         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 357         return;
 358 }
 359
 360 void
 361 generate_additional_parameters(RSA *rsa)
 362 {
 363         BIGNUM *aux;
 364         BN_CTX *ctx;
 365         /* Generate additional parameters */
 366         aux = BN_new();
 367         ctx = BN_CTX_new();
 368
 369         BN_sub(aux, rsa->q, BN_value_one());
 370         BN_mod(rsa->dmq1, rsa->d, aux, ctx);
 371
 372         BN_sub(aux, rsa->p, BN_value_one());
 373         BN_mod(rsa->dmp1, rsa->d, aux, ctx);
 374
 375         BN_clear_free(aux);
 376         BN_CTX_free(ctx);
 377 }
 378
 379 void
 380 process_add_identity(SocketEntry *e, int version)
 381 {
 382         Key *k = NULL;
 383         char *type_name;
 384         char *comment;
 385         int type, success = 0;
 386         Idtab *tab = idtab_lookup(version);
 387
 388         switch (version) {
 389         case 1:
 390                 k = key_new_private(KEY_RSA1);
 391                 buffer_get_int(&e->input);                      /* ignored */
 392                 buffer_get_bignum(&e->input, k->rsa->n);
 393                 buffer_get_bignum(&e->input, k->rsa->e);
 394                 buffer_get_bignum(&e->input, k->rsa->d);
 395                 buffer_get_bignum(&e->input, k->rsa->iqmp);
 396
 397                 /* SSH and SSL have p and q swapped */
 398                 buffer_get_bignum(&e->input, k->rsa->q);        /* p */
 399                 buffer_get_bignum(&e->input, k->rsa->p);        /* q */
 400
 401                 /* Generate additional parameters */
 402                 generate_additional_parameters(k->rsa);
 403                 break;
 404         case 2:
 405                 type_name = buffer_get_string(&e->input, NULL);
 406                 type = key_type_from_name(type_name);
 407                 xfree(type_name);
 408                 switch(type) {
 409                 case KEY_DSA:
 410                         k = key_new_private(type);
 411                         buffer_get_bignum2(&e->input, k->dsa->p);
 412                         buffer_get_bignum2(&e->input, k->dsa->q);
 413                         buffer_get_bignum2(&e->input, k->dsa->g);
 414                         buffer_get_bignum2(&e->input, k->dsa->pub_key);
 415                         buffer_get_bignum2(&e->input, k->dsa->priv_key);
 416                         break;
 417                 case KEY_RSA:
 418                         k = key_new_private(type);
 419                         buffer_get_bignum2(&e->input, k->rsa->n);
 420                         buffer_get_bignum2(&e->input, k->rsa->e);
 421                         buffer_get_bignum2(&e->input, k->rsa->d);
 422                         buffer_get_bignum2(&e->input, k->rsa->iqmp);
 423                         buffer_get_bignum2(&e->input, k->rsa->p);
 424                         buffer_get_bignum2(&e->input, k->rsa->q);
 425
 426                         /* Generate additional parameters */
 427                         generate_additional_parameters(k->rsa);
 428                         break;
 429                 default:
 430                         buffer_clear(&e->input);
 431                         goto send;
 432                 }
 433                 break;
 434         }
 435         comment = buffer_get_string(&e->input, NULL);
 436         if (k == NULL) {
 437                 xfree(comment);
 438                 goto send;
 439         }
 440         success = 1;
 441         if (lookup_private_key(k, NULL, version) == NULL) {
 442                 if (tab->nentries == 0)
 443                         tab->identities = xmalloc(sizeof(Identity));
 444                 else
 445                         tab->identities = xrealloc(tab->identities,
 446                             (tab->nentries + 1) * sizeof(Identity));
 447                 tab->identities[tab->nentries].key = k;
 448                 tab->identities[tab->nentries].comment = comment;
 449                 /* Increment the number of identities. */
 450                 tab->nentries++;
 451         } else {
 452                 key_free(k);
 453                 xfree(comment);
 454         }
 455 send:
 456         buffer_put_int(&e->output, 1);
 457         buffer_put_char(&e->output,
 458             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 459 }
 460
 461 /* dispatch incoming messages */
 462
 463 void
 464 process_message(SocketEntry *e)
 465 {
 466         unsigned int msg_len;
 467         unsigned int type;
 468         unsigned char *cp;
 469         if (buffer_len(&e->input) < 5)
 470                 return;         /* Incomplete message. */
 471         cp = (unsigned char *) buffer_ptr(&e->input);
 472         msg_len = GET_32BIT(cp);
 473         if (msg_len > 256 * 1024) {
 474                 shutdown(e->fd, SHUT_RDWR);
 475                 close(e->fd);
 476                 e->type = AUTH_UNUSED;
 477                 return;
 478         }
 479         if (buffer_len(&e->input) < msg_len + 4)
 480                 return;
 481         buffer_consume(&e->input, 4);
 482         type = buffer_get_char(&e->input);
 483
 484         switch (type) {
 485         /* ssh1 */
 486         case SSH_AGENTC_RSA_CHALLENGE:
 487                 process_authentication_challenge1(e);
 488                 break;
 489         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 490                 process_request_identities(e, 1);
 491                 break;
 492         case SSH_AGENTC_ADD_RSA_IDENTITY:
 493                 process_add_identity(e, 1);
 494                 break;
 495         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 496                 process_remove_identity(e, 1);
 497                 break;
 498         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 499                 process_remove_all_identities(e, 1);
 500                 break;
 501         /* ssh2 */
 502         case SSH2_AGENTC_SIGN_REQUEST:
 503                 process_sign_request2(e);
 504                 break;
 505         case SSH2_AGENTC_REQUEST_IDENTITIES:
 506                 process_request_identities(e, 2);
 507                 break;
 508         case SSH2_AGENTC_ADD_IDENTITY:
 509                 process_add_identity(e, 2);
 510                 break;
 511         case SSH2_AGENTC_REMOVE_IDENTITY:
 512                 process_remove_identity(e, 2);
 513                 break;
 514         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 515                 process_remove_all_identities(e, 2);
 516                 break;
 517         default:
 518                 /* Unknown message.  Respond with failure. */
 519                 error("Unknown message %d", type);
 520                 buffer_clear(&e->input);
 521                 buffer_put_int(&e->output, 1);
 522                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 523                 break;
 524         }
 525 }
 526
 527 void
 528 new_socket(int type, int fd)
 529 {
 530         unsigned int i, old_alloc;
 531         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 532                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 533
 534         if (fd > max_fd)
 535                 max_fd = fd;
 536
 537         for (i = 0; i < sockets_alloc; i++)
 538                 if (sockets[i].type == AUTH_UNUSED) {
 539                         sockets[i].fd = fd;
 540                         sockets[i].type = type;
 541                         buffer_init(&sockets[i].input);
 542                         buffer_init(&sockets[i].output);
 543                         return;
 544                 }
 545         old_alloc = sockets_alloc;
 546         sockets_alloc += 10;
 547         if (sockets)
 548                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 549         else
 550                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 551         for (i = old_alloc; i < sockets_alloc; i++)
 552                 sockets[i].type = AUTH_UNUSED;
 553         sockets[old_alloc].type = type;
 554         sockets[old_alloc].fd = fd;
 555         buffer_init(&sockets[old_alloc].input);
 556         buffer_init(&sockets[old_alloc].output);
 557 }
 558
 559 void
 560 prepare_select(fd_set *readset, fd_set *writeset)
 561 {
 562         unsigned int i;
 563         for (i = 0; i < sockets_alloc; i++)
 564                 switch (sockets[i].type) {
 565                 case AUTH_SOCKET:
 566                 case AUTH_CONNECTION:
 567                         FD_SET(sockets[i].fd, readset);
 568                         if (buffer_len(&sockets[i].output) > 0)
 569                                 FD_SET(sockets[i].fd, writeset);
 570                         break;
 571                 case AUTH_UNUSED:
 572                         break;
 573                 default:
 574                         fatal("Unknown socket type %d", sockets[i].type);
 575                         break;
 576                 }
 577 }
 578
 579 void
 580 after_select(fd_set *readset, fd_set *writeset)
 581 {
 582         unsigned int i;
 583         int len, sock;
 584         socklen_t slen;
 585         char buf[1024];
 586         struct sockaddr_un sunaddr;
 587
 588         for (i = 0; i < sockets_alloc; i++)
 589                 switch (sockets[i].type) {
 590                 case AUTH_UNUSED:
 591                         break;
 592                 case AUTH_SOCKET:
 593                         if (FD_ISSET(sockets[i].fd, readset)) {
 594                                 slen = sizeof(sunaddr);
 595                                 sock = accept(sockets[i].fd, (struct sockaddr *) & sunaddr, &slen);
 596                                 if (sock < 0) {
 597                                         perror("accept from AUTH_SOCKET");
 598                                         break;
 599                                 }
 600                                 new_socket(AUTH_CONNECTION, sock);
 601                         }
 602                         break;
 603                 case AUTH_CONNECTION:
 604                         if (buffer_len(&sockets[i].output) > 0 &&
 605                             FD_ISSET(sockets[i].fd, writeset)) {
 606                                 len = write(sockets[i].fd, buffer_ptr(&sockets[i].output),
 607                                          buffer_len(&sockets[i].output));
 608                                 if (len <= 0) {
 609                                         shutdown(sockets[i].fd, SHUT_RDWR);
 610                                         close(sockets[i].fd);
 611                                         sockets[i].type = AUTH_UNUSED;
 612                                         buffer_free(&sockets[i].input);
 613                                         buffer_free(&sockets[i].output);
 614                                         break;
 615                                 }
 616                                 buffer_consume(&sockets[i].output, len);
 617                         }
 618                         if (FD_ISSET(sockets[i].fd, readset)) {
 619                                 len = read(sockets[i].fd, buf, sizeof(buf));
 620                                 if (len <= 0) {
 621                                         shutdown(sockets[i].fd, SHUT_RDWR);
 622                                         close(sockets[i].fd);
 623                                         sockets[i].type = AUTH_UNUSED;
 624                                         buffer_free(&sockets[i].input);
 625                                         buffer_free(&sockets[i].output);
 626                                         break;
 627                                 }
 628                                 buffer_append(&sockets[i].input, buf, len);
 629                                 process_message(&sockets[i]);
 630                         }
 631                         break;
 632                 default:
 633                         fatal("Unknown type %d", sockets[i].type);
 634                 }
 635 }
 636
 637 void
 638 check_parent_exists(int sig)
 639 {
 640         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 641                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 642                 exit(1);
 643         }
 644         signal(SIGALRM, check_parent_exists);
 645         alarm(10);
 646 }
 647
 648 void
 649 cleanup_socket(void)
 650 {
 651         unlink(socket_name);
 652         rmdir(socket_dir);
 653 }
 654
 655 void
 656 cleanup_exit(int i)
 657 {
 658         cleanup_socket();
 659         exit(i);
 660 }
 661
 662 void
 663 usage()
 664 {
 665         fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION);
 666         fprintf(stderr, "Usage: %s [-c | -s] [-k] [command {args...]]\n",
 667                 __progname);
 668         exit(1);
 669 }
 670
 671 int
 672 main(int ac, char **av)
 673 {
 674         fd_set readset, writeset;
 675         int sock, c_flag = 0, k_flag = 0, s_flag = 0, ch;
 676         struct sockaddr_un sunaddr;
 677         struct rlimit rlim;
 678         pid_t pid;
 679         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 680         extern int optind;
 681
 682         __progname = get_progname(av[0]);
 683         init_rng();
 684
 685 #ifdef __GNU_LIBRARY__
 686         while ((ch = getopt(ac, av, "+cks")) != -1) {
 687 #else /* __GNU_LIBRARY__ */
 688         while ((ch = getopt(ac, av, "cks")) != -1) {
 689 #endif /* __GNU_LIBRARY__ */
 690                 switch (ch) {
 691                 case 'c':
 692                         if (s_flag)
 693                                 usage();
 694                         c_flag++;
 695                         break;
 696                 case 'k':
 697                         k_flag++;
 698                         break;
 699                 case 's':
 700                         if (c_flag)
 701                                 usage();
 702                         s_flag++;
 703                         break;
 704                 default:
 705                         usage();
 706                 }
 707         }
 708         ac -= optind;
 709         av += optind;
 710
 711         if (ac > 0 && (c_flag || k_flag || s_flag))
 712                 usage();
 713
 714         if (ac == 0 && !c_flag && !k_flag && !s_flag) {
 715                 shell = getenv("SHELL");
 716                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 717                         c_flag = 1;
 718         }
 719         if (k_flag) {
 720                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 721                 if (pidstr == NULL) {
 722                         fprintf(stderr, "%s not set, cannot kill agent\n",
 723                                 SSH_AGENTPID_ENV_NAME);
 724                         exit(1);
 725                 }
 726                 pid = atoi(pidstr);
 727                 if (pid < 1) {  /* XXX PID_MAX check too */
 728                 /* Yes, PID_MAX check please */
 729                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 730                                 SSH_AGENTPID_ENV_NAME, pidstr);
 731                         exit(1);
 732                 }
 733                 if (kill(pid, SIGTERM) == -1) {
 734                         perror("kill");
 735                         exit(1);
 736                 }
 737                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 738                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 739                 printf(format, SSH_AGENTPID_ENV_NAME);
 740                 printf("echo Agent pid %d killed;\n", pid);
 741                 exit(0);
 742         }
 743         parent_pid = getpid();
 744
 745         /* Create private directory for agent socket */
 746         strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 747         if (mkdtemp(socket_dir) == NULL) {
 748                 perror("mkdtemp: private socket dir");
 749                 exit(1);
 750         }
 751         snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 752                  parent_pid);
 753
 754         /*
 755          * Create socket early so it will exist before command gets run from
 756          * the parent.
 757          */
 758         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 759         if (sock < 0) {
 760                 perror("socket");
 761                 cleanup_exit(1);
 762         }
 763         memset(&sunaddr, 0, sizeof(sunaddr));
 764         sunaddr.sun_family = AF_UNIX;
 765         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 766         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 767                 perror("bind");
 768                 cleanup_exit(1);
 769         }
 770         if (listen(sock, 5) < 0) {
 771                 perror("listen");
 772                 cleanup_exit(1);
 773         }
 774         /*
 775          * Fork, and have the parent execute the command, if any, or present
 776          * the socket data.  The child continues as the authentication agent.
 777          */
 778         pid = fork();
 779         if (pid == -1) {
 780                 perror("fork");
 781                 exit(1);
 782         }
 783         if (pid != 0) {         /* Parent - execute the given command. */
 784                 close(sock);
 785                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 786                 if (ac == 0) {
 787                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 788                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 789                                SSH_AUTHSOCKET_ENV_NAME);
 790                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 791                                SSH_AGENTPID_ENV_NAME);
 792                         printf("echo Agent pid %d;\n", pid);
 793                         exit(0);
 794                 }
 795                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 796                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 797                         perror("setenv");
 798                         exit(1);
 799                 }
 800                 execvp(av[0], av);
 801                 perror(av[0]);
 802                 exit(1);
 803         }
 804         close(0);
 805         close(1);
 806         close(2);
 807
 808         /* deny core dumps, since memory contains unencrypted private keys */
 809         rlim.rlim_cur = rlim.rlim_max = 0;
 810         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
 811                 perror("setrlimit rlimit_core failed");
 812                 cleanup_exit(1);
 813         }
 814         if (setsid() == -1) {
 815                 perror("setsid");
 816                 cleanup_exit(1);
 817         }
 818         if (atexit(cleanup_socket) < 0) {
 819                 perror("atexit");
 820                 cleanup_exit(1);
 821         }
 822         new_socket(AUTH_SOCKET, sock);
 823         if (ac > 0) {
 824                 signal(SIGALRM, check_parent_exists);
 825                 alarm(10);
 826         }
 827         idtab_init();
 828         signal(SIGINT, SIG_IGN);
 829         signal(SIGPIPE, SIG_IGN);
 830         signal(SIGHUP, cleanup_exit);
 831         signal(SIGTERM, cleanup_exit);
 832         while (1) {
 833                 FD_ZERO(&readset);
 834                 FD_ZERO(&writeset);
 835                 prepare_select(&readset, &writeset);
 836                 if (select(max_fd + 1, &readset, &writeset, NULL, NULL) < 0) {
 837                         if (errno == EINTR)
 838                                 continue;
 839                         exit(1);
 840                 }
 841                 after_select(&readset, &writeset);
 842         }
 843         /* NOTREACHED */
 844 }