ssh-agent.c

   1 /*      $OpenBSD: ssh-agent.c,v 1.55 2001/06/23 15:12:20 itojun 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 1.55 2001/06/23 15:12:20 itojun 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 static 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 static 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 static 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 static 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                         u_char *blob;
 155                         u_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 static 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         u_char buf[32], mdbuf[16], session_id[16];
 177         u_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                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 200                         goto failure;
 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 static void
 235 process_sign_request2(SocketEntry *e)
 236 {
 237         extern int datafellows;
 238         Key *key, *private;
 239         u_char *blob, *data, *signature = NULL;
 240         u_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 = key_from_blob(blob, blen);
 255         if (key != NULL) {
 256                 private = lookup_private_key(key, NULL, 2);
 257                 if (private != NULL)
 258                         ok = key_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 static void
 280 process_remove_identity(SocketEntry *e, int version)
 281 {
 282         Key *key = NULL, *private;
 283         u_char *blob;
 284         u_int blen;
 285         u_int bits;
 286         int success = 0;
 287
 288         switch(version){
 289         case 1:
 290                 key = key_new(KEY_RSA1);
 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 = 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 move
 313                          * all the entries between the empty slot and the end
 314                          * of the array.
 315                          */
 316                         Idtab *tab = idtab_lookup(version);
 317                         key_free(tab->identities[idx].key);
 318                         xfree(tab->identities[idx].comment);
 319                         if (tab->nentries < 1)
 320                                 fatal("process_remove_identity: "
 321                                     "internal error: tab->nentries %d",
 322                                     tab->nentries);
 323                         if (idx != tab->nentries - 1) {
 324                                 int i;
 325                                 for (i = idx; i < tab->nentries - 1; i++)
 326                                         tab->identities[i] = tab->identities[i+1];
 327                         }
 328                         tab->identities[tab->nentries - 1].key = NULL;
 329                         tab->identities[tab->nentries - 1].comment = NULL;
 330                         tab->nentries--;
 331                         success = 1;
 332                 }
 333                 key_free(key);
 334         }
 335         buffer_put_int(&e->output, 1);
 336         buffer_put_char(&e->output,
 337             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 338 }
 339
 340 static void
 341 process_remove_all_identities(SocketEntry *e, int version)
 342 {
 343         u_int i;
 344         Idtab *tab = idtab_lookup(version);
 345
 346         /* Loop over all identities and clear the keys. */
 347         for (i = 0; i < tab->nentries; i++) {
 348                 key_free(tab->identities[i].key);
 349                 xfree(tab->identities[i].comment);
 350         }
 351
 352         /* Mark that there are no identities. */
 353         tab->nentries = 0;
 354
 355         /* Send success. */
 356         buffer_put_int(&e->output, 1);
 357         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 358         return;
 359 }
 360
 361 static void
 362 process_add_identity(SocketEntry *e, int version)
 363 {
 364         Key *k = NULL;
 365         char *type_name;
 366         char *comment;
 367         int type, success = 0;
 368         Idtab *tab = idtab_lookup(version);
 369
 370         switch (version) {
 371         case 1:
 372                 k = key_new_private(KEY_RSA1);
 373                 buffer_get_int(&e->input);                      /* ignored */
 374                 buffer_get_bignum(&e->input, k->rsa->n);
 375                 buffer_get_bignum(&e->input, k->rsa->e);
 376                 buffer_get_bignum(&e->input, k->rsa->d);
 377                 buffer_get_bignum(&e->input, k->rsa->iqmp);
 378
 379                 /* SSH and SSL have p and q swapped */
 380                 buffer_get_bignum(&e->input, k->rsa->q);        /* p */
 381                 buffer_get_bignum(&e->input, k->rsa->p);        /* q */
 382
 383                 /* Generate additional parameters */
 384                 generate_additional_parameters(k->rsa);
 385                 break;
 386         case 2:
 387                 type_name = buffer_get_string(&e->input, NULL);
 388                 type = key_type_from_name(type_name);
 389                 xfree(type_name);
 390                 switch(type) {
 391                 case KEY_DSA:
 392                         k = key_new_private(type);
 393                         buffer_get_bignum2(&e->input, k->dsa->p);
 394                         buffer_get_bignum2(&e->input, k->dsa->q);
 395                         buffer_get_bignum2(&e->input, k->dsa->g);
 396                         buffer_get_bignum2(&e->input, k->dsa->pub_key);
 397                         buffer_get_bignum2(&e->input, k->dsa->priv_key);
 398                         break;
 399                 case KEY_RSA:
 400                         k = key_new_private(type);
 401                         buffer_get_bignum2(&e->input, k->rsa->n);
 402                         buffer_get_bignum2(&e->input, k->rsa->e);
 403                         buffer_get_bignum2(&e->input, k->rsa->d);
 404                         buffer_get_bignum2(&e->input, k->rsa->iqmp);
 405                         buffer_get_bignum2(&e->input, k->rsa->p);
 406                         buffer_get_bignum2(&e->input, k->rsa->q);
 407
 408                         /* Generate additional parameters */
 409                         generate_additional_parameters(k->rsa);
 410                         break;
 411                 default:
 412                         buffer_clear(&e->input);
 413                         goto send;
 414                 }
 415                 break;
 416         }
 417         comment = buffer_get_string(&e->input, NULL);
 418         if (k == NULL) {
 419                 xfree(comment);
 420                 goto send;
 421         }
 422         success = 1;
 423         if (lookup_private_key(k, NULL, version) == NULL) {
 424                 if (tab->nentries == 0)
 425                         tab->identities = xmalloc(sizeof(Identity));
 426                 else
 427                         tab->identities = xrealloc(tab->identities,
 428                             (tab->nentries + 1) * sizeof(Identity));
 429                 tab->identities[tab->nentries].key = k;
 430                 tab->identities[tab->nentries].comment = comment;
 431                 /* Increment the number of identities. */
 432                 tab->nentries++;
 433         } else {
 434                 key_free(k);
 435                 xfree(comment);
 436         }
 437 send:
 438         buffer_put_int(&e->output, 1);
 439         buffer_put_char(&e->output,
 440             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 441 }
 442
 443 /* dispatch incoming messages */
 444
 445 static void
 446 process_message(SocketEntry *e)
 447 {
 448         u_int msg_len;
 449         u_int type;
 450         u_char *cp;
 451         if (buffer_len(&e->input) < 5)
 452                 return;         /* Incomplete message. */
 453         cp = (u_char *) buffer_ptr(&e->input);
 454         msg_len = GET_32BIT(cp);
 455         if (msg_len > 256 * 1024) {
 456                 shutdown(e->fd, SHUT_RDWR);
 457                 close(e->fd);
 458                 e->type = AUTH_UNUSED;
 459                 return;
 460         }
 461         if (buffer_len(&e->input) < msg_len + 4)
 462                 return;
 463         buffer_consume(&e->input, 4);
 464         type = buffer_get_char(&e->input);
 465
 466         switch (type) {
 467         /* ssh1 */
 468         case SSH_AGENTC_RSA_CHALLENGE:
 469                 process_authentication_challenge1(e);
 470                 break;
 471         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 472                 process_request_identities(e, 1);
 473                 break;
 474         case SSH_AGENTC_ADD_RSA_IDENTITY:
 475                 process_add_identity(e, 1);
 476                 break;
 477         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 478                 process_remove_identity(e, 1);
 479                 break;
 480         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 481                 process_remove_all_identities(e, 1);
 482                 break;
 483         /* ssh2 */
 484         case SSH2_AGENTC_SIGN_REQUEST:
 485                 process_sign_request2(e);
 486                 break;
 487         case SSH2_AGENTC_REQUEST_IDENTITIES:
 488                 process_request_identities(e, 2);
 489                 break;
 490         case SSH2_AGENTC_ADD_IDENTITY:
 491                 process_add_identity(e, 2);
 492                 break;
 493         case SSH2_AGENTC_REMOVE_IDENTITY:
 494                 process_remove_identity(e, 2);
 495                 break;
 496         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 497                 process_remove_all_identities(e, 2);
 498                 break;
 499         default:
 500                 /* Unknown message.  Respond with failure. */
 501                 error("Unknown message %d", type);
 502                 buffer_clear(&e->input);
 503                 buffer_put_int(&e->output, 1);
 504                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 505                 break;
 506         }
 507 }
 508
 509 static void
 510 new_socket(int type, int fd)
 511 {
 512         u_int i, old_alloc;
 513         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 514                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 515
 516         if (fd > max_fd)
 517                 max_fd = fd;
 518
 519         for (i = 0; i < sockets_alloc; i++)
 520                 if (sockets[i].type == AUTH_UNUSED) {
 521                         sockets[i].fd = fd;
 522                         sockets[i].type = type;
 523                         buffer_init(&sockets[i].input);
 524                         buffer_init(&sockets[i].output);
 525                         return;
 526                 }
 527         old_alloc = sockets_alloc;
 528         sockets_alloc += 10;
 529         if (sockets)
 530                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 531         else
 532                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 533         for (i = old_alloc; i < sockets_alloc; i++)
 534                 sockets[i].type = AUTH_UNUSED;
 535         sockets[old_alloc].type = type;
 536         sockets[old_alloc].fd = fd;
 537         buffer_init(&sockets[old_alloc].input);
 538         buffer_init(&sockets[old_alloc].output);
 539 }
 540
 541 static int
 542 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl)
 543 {
 544         u_int i, sz;
 545         int n = 0;
 546
 547         for (i = 0; i < sockets_alloc; i++) {
 548                 switch (sockets[i].type) {
 549                 case AUTH_SOCKET:
 550                 case AUTH_CONNECTION:
 551                         n = MAX(n, sockets[i].fd);
 552                         break;
 553                 case AUTH_UNUSED:
 554                         break;
 555                 default:
 556                         fatal("Unknown socket type %d", sockets[i].type);
 557                         break;
 558                 }
 559         }
 560
 561         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 562         if (*fdrp == NULL || n > *fdl) {
 563                 if (*fdrp)
 564                         xfree(*fdrp);
 565                 if (*fdwp)
 566                         xfree(*fdwp);
 567                 *fdrp = xmalloc(sz);
 568                 *fdwp = xmalloc(sz);
 569                 *fdl = n;
 570         }
 571         memset(*fdrp, 0, sz);
 572         memset(*fdwp, 0, sz);
 573
 574         for (i = 0; i < sockets_alloc; i++) {
 575                 switch (sockets[i].type) {
 576                 case AUTH_SOCKET:
 577                 case AUTH_CONNECTION:
 578                         FD_SET(sockets[i].fd, *fdrp);
 579                         if (buffer_len(&sockets[i].output) > 0)
 580                                 FD_SET(sockets[i].fd, *fdwp);
 581                         break;
 582                 default:
 583                         break;
 584                 }
 585         }
 586         return (1);
 587 }
 588
 589 static void
 590 after_select(fd_set *readset, fd_set *writeset)
 591 {
 592         u_int i;
 593         int len, sock;
 594         socklen_t slen;
 595         char buf[1024];
 596         struct sockaddr_un sunaddr;
 597
 598         for (i = 0; i < sockets_alloc; i++)
 599                 switch (sockets[i].type) {
 600                 case AUTH_UNUSED:
 601                         break;
 602                 case AUTH_SOCKET:
 603                         if (FD_ISSET(sockets[i].fd, readset)) {
 604                                 slen = sizeof(sunaddr);
 605                                 sock = accept(sockets[i].fd,
 606                                     (struct sockaddr *) &sunaddr, &slen);
 607                                 if (sock < 0) {
 608                                         perror("accept from AUTH_SOCKET");
 609                                         break;
 610                                 }
 611                                 new_socket(AUTH_CONNECTION, sock);
 612                         }
 613                         break;
 614                 case AUTH_CONNECTION:
 615                         if (buffer_len(&sockets[i].output) > 0 &&
 616                             FD_ISSET(sockets[i].fd, writeset)) {
 617                                 do {
 618                                         len = write(sockets[i].fd,
 619                                             buffer_ptr(&sockets[i].output),
 620                                             buffer_len(&sockets[i].output));
 621                                         if (len == -1 && (errno == EAGAIN ||
 622                                             errno == EINTR))
 623                                                 continue;
 624                                         break;
 625                                 } while (1);
 626                                 if (len <= 0) {
 627                                         shutdown(sockets[i].fd, SHUT_RDWR);
 628                                         close(sockets[i].fd);
 629                                         sockets[i].type = AUTH_UNUSED;
 630                                         buffer_free(&sockets[i].input);
 631                                         buffer_free(&sockets[i].output);
 632                                         break;
 633                                 }
 634                                 buffer_consume(&sockets[i].output, len);
 635                         }
 636                         if (FD_ISSET(sockets[i].fd, readset)) {
 637                                 do {
 638                                         len = read(sockets[i].fd, buf, sizeof(buf));
 639                                         if (len == -1 && (errno == EAGAIN ||
 640                                             errno == EINTR))
 641                                                 continue;
 642                                         break;
 643                                 } while (1);
 644                                 if (len <= 0) {
 645                                         shutdown(sockets[i].fd, SHUT_RDWR);
 646                                         close(sockets[i].fd);
 647                                         sockets[i].type = AUTH_UNUSED;
 648                                         buffer_free(&sockets[i].input);
 649                                         buffer_free(&sockets[i].output);
 650                                         break;
 651                                 }
 652                                 buffer_append(&sockets[i].input, buf, len);
 653                                 process_message(&sockets[i]);
 654                         }
 655                         break;
 656                 default:
 657                         fatal("Unknown type %d", sockets[i].type);
 658                 }
 659 }
 660
 661 static void
 662 check_parent_exists(int sig)
 663 {
 664         int save_errno = errno;
 665
 666         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 667                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 668                 exit(1);
 669         }
 670         signal(SIGALRM, check_parent_exists);
 671         alarm(10);
 672         errno = save_errno;
 673 }
 674
 675 static void
 676 cleanup_socket(void)
 677 {
 678         if (socket_name[0])
 679                 unlink(socket_name);
 680         if (socket_dir[0])
 681                 rmdir(socket_dir);
 682 }
 683
 684 static void
 685 cleanup_exit(int i)
 686 {
 687         cleanup_socket();
 688         exit(i);
 689 }
 690
 691 static void
 692 cleanup_handler(int sig)
 693 {
 694         cleanup_socket();
 695         _exit(2);
 696 }
 697
 698 static void
 699 usage(void)
 700 {
 701         fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION);
 702         fprintf(stderr, "Usage: %s [-c | -s] [-k] [command {args...]]\n",
 703             __progname);
 704         exit(1);
 705 }
 706
 707 int
 708 main(int ac, char **av)
 709 {
 710         int sock, c_flag = 0, k_flag = 0, s_flag = 0, ch;
 711         struct sockaddr_un sunaddr;
 712 #ifdef HAVE_SETRLIMIT
 713         struct rlimit rlim;
 714 #endif
 715 #ifdef HAVE_CYGWIN
 716         int prev_mask;
 717 #endif
 718         pid_t pid;
 719         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 720         extern int optind;
 721         fd_set *readsetp = NULL, *writesetp = NULL;
 722
 723         SSLeay_add_all_algorithms();
 724
 725         __progname = get_progname(av[0]);
 726         init_rng();
 727         seed_rng();
 728
 729 #ifdef __GNU_LIBRARY__
 730         while ((ch = getopt(ac, av, "+cks")) != -1) {
 731 #else /* __GNU_LIBRARY__ */
 732         while ((ch = getopt(ac, av, "cks")) != -1) {
 733 #endif /* __GNU_LIBRARY__ */
 734                 switch (ch) {
 735                 case 'c':
 736                         if (s_flag)
 737                                 usage();
 738                         c_flag++;
 739                         break;
 740                 case 'k':
 741                         k_flag++;
 742                         break;
 743                 case 's':
 744                         if (c_flag)
 745                                 usage();
 746                         s_flag++;
 747                         break;
 748                 default:
 749                         usage();
 750                 }
 751         }
 752         ac -= optind;
 753         av += optind;
 754
 755         if (ac > 0 && (c_flag || k_flag || s_flag))
 756                 usage();
 757
 758         if (ac == 0 && !c_flag && !k_flag && !s_flag) {
 759                 shell = getenv("SHELL");
 760                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 761                         c_flag = 1;
 762         }
 763         if (k_flag) {
 764                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 765                 if (pidstr == NULL) {
 766                         fprintf(stderr, "%s not set, cannot kill agent\n",
 767                             SSH_AGENTPID_ENV_NAME);
 768                         exit(1);
 769                 }
 770                 pid = atoi(pidstr);
 771                 if (pid < 1) {
 772                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 773                             SSH_AGENTPID_ENV_NAME, pidstr);
 774                         exit(1);
 775                 }
 776                 if (kill(pid, SIGTERM) == -1) {
 777                         perror("kill");
 778                         exit(1);
 779                 }
 780                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 781                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 782                 printf(format, SSH_AGENTPID_ENV_NAME);
 783                 printf("echo Agent pid %d killed;\n", pid);
 784                 exit(0);
 785         }
 786         parent_pid = getpid();
 787
 788         /* Create private directory for agent socket */
 789         strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 790         if (mkdtemp(socket_dir) == NULL) {
 791                 perror("mkdtemp: private socket dir");
 792                 exit(1);
 793         }
 794         snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 795             parent_pid);
 796
 797         /*
 798          * Create socket early so it will exist before command gets run from
 799          * the parent.
 800          */
 801         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 802         if (sock < 0) {
 803                 perror("socket");
 804                 cleanup_exit(1);
 805         }
 806         memset(&sunaddr, 0, sizeof(sunaddr));
 807         sunaddr.sun_family = AF_UNIX;
 808         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 809 #ifdef HAVE_CYGWIN
 810         prev_mask = umask(0177);
 811 #endif
 812         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 813                 perror("bind");
 814 #ifdef HAVE_CYGWIN
 815                 umask(prev_mask);
 816 #endif
 817                 cleanup_exit(1);
 818         }
 819 #ifdef HAVE_CYGWIN
 820         umask(prev_mask);
 821 #endif
 822         if (listen(sock, 5) < 0) {
 823                 perror("listen");
 824                 cleanup_exit(1);
 825         }
 826
 827         /*
 828          * Fork, and have the parent execute the command, if any, or present
 829          * the socket data.  The child continues as the authentication agent.
 830          */
 831         pid = fork();
 832         if (pid == -1) {
 833                 perror("fork");
 834                 exit(1);
 835         }
 836         if (pid != 0) {         /* Parent - execute the given command. */
 837                 close(sock);
 838                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 839                 if (ac == 0) {
 840                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 841                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 842                             SSH_AUTHSOCKET_ENV_NAME);
 843                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 844                             SSH_AGENTPID_ENV_NAME);
 845                         printf("echo Agent pid %d;\n", pid);
 846                         exit(0);
 847                 }
 848                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 849                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 850                         perror("setenv");
 851                         exit(1);
 852                 }
 853                 execvp(av[0], av);
 854                 perror(av[0]);
 855                 exit(1);
 856         }
 857         close(0);
 858         close(1);
 859         close(2);
 860
 861 #ifdef HAVE_SETRLIMIT
 862         /* deny core dumps, since memory contains unencrypted private keys */
 863         rlim.rlim_cur = rlim.rlim_max = 0;
 864         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
 865                 perror("setrlimit rlimit_core failed");
 866                 cleanup_exit(1);
 867         }
 868 #endif
 869         if (setsid() == -1) {
 870                 perror("setsid");
 871                 cleanup_exit(1);
 872         }
 873         if (atexit(cleanup_socket) < 0) {
 874                 perror("atexit");
 875                 cleanup_exit(1);
 876         }
 877         new_socket(AUTH_SOCKET, sock);
 878         if (ac > 0) {
 879                 signal(SIGALRM, check_parent_exists);
 880                 alarm(10);
 881         }
 882         idtab_init();
 883         signal(SIGINT, SIG_IGN);
 884         signal(SIGPIPE, SIG_IGN);
 885         signal(SIGHUP, cleanup_handler);
 886         signal(SIGTERM, cleanup_handler);
 887         while (1) {
 888                 prepare_select(&readsetp, &writesetp, &max_fd);
 889                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
 890                         if (errno == EINTR)
 891                                 continue;
 892                         exit(1);
 893                 }
 894                 after_select(readsetp, writesetp);
 895         }
 896         /* NOTREACHED */
 897 }