ssh-agent.c

   1 /*      $OpenBSD: ssh-agent.c,v 1.54 2001/04/03 13:56:11 stevesk 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 1.54 2001/04/03 13:56:11 stevesk Exp $");
  41
  42 #include <openssl/evp.h>
  43 #include <openssl/md5.h>
  44
  45 #include "ssh.h"
  46 #include "rsa.h"
  47 #include "buffer.h"
  48 #include "bufaux.h"
  49 #include "xmalloc.h"
  50 #include "packet.h"
  51 #include "getput.h"
  52 #include "mpaux.h"
  53 #include "key.h"
  54 #include "authfd.h"
  55 #include "cipher.h"
  56 #include "kex.h"
  57 #include "compat.h"
  58 #include "log.h"
  59
  60 typedef struct {
  61         int fd;
  62         enum {
  63                 AUTH_UNUSED, AUTH_SOCKET, AUTH_CONNECTION
  64         } type;
  65         Buffer input;
  66         Buffer output;
  67 } SocketEntry;
  68
  69 u_int sockets_alloc = 0;
  70 SocketEntry *sockets = NULL;
  71
  72 typedef struct {
  73         Key *key;
  74         char *comment;
  75 } Identity;
  76
  77 typedef struct {
  78         int nentries;
  79         Identity *identities;
  80 } Idtab;
  81
  82 /* private key table, one per protocol version */
  83 Idtab idtable[3];
  84
  85 int max_fd = 0;
  86
  87 /* pid of shell == parent of agent */
  88 pid_t parent_pid = -1;
  89
  90 /* pathname and directory for AUTH_SOCKET */
  91 char socket_name[1024];
  92 char socket_dir[1024];
  93
  94 #ifdef HAVE___PROGNAME
  95 extern char *__progname;
  96 #else
  97 char *__progname;
  98 #endif
  99
 100 int     prepare_select(fd_set **, fd_set **, int *);
 101
 102 void
 103 idtab_init(void)
 104 {
 105         int i;
 106         for (i = 0; i <=2; i++){
 107                 idtable[i].identities = NULL;
 108                 idtable[i].nentries = 0;
 109         }
 110 }
 111
 112 /* return private key table for requested protocol version */
 113 Idtab *
 114 idtab_lookup(int version)
 115 {
 116         if (version < 1 || version > 2)
 117                 fatal("internal error, bad protocol version %d", version);
 118         return &idtable[version];
 119 }
 120
 121 /* return matching private key for given public key */
 122 Key *
 123 lookup_private_key(Key *key, int *idx, int version)
 124 {
 125         int i;
 126         Idtab *tab = idtab_lookup(version);
 127         for (i = 0; i < tab->nentries; i++) {
 128                 if (key_equal(key, tab->identities[i].key)) {
 129                         if (idx != NULL)
 130                                 *idx = i;
 131                         return tab->identities[i].key;
 132                 }
 133         }
 134         return NULL;
 135 }
 136
 137 /* send list of supported public keys to 'client' */
 138 void
 139 process_request_identities(SocketEntry *e, int version)
 140 {
 141         Idtab *tab = idtab_lookup(version);
 142         Buffer msg;
 143         int i;
 144
 145         buffer_init(&msg);
 146         buffer_put_char(&msg, (version == 1) ?
 147             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 148         buffer_put_int(&msg, tab->nentries);
 149         for (i = 0; i < tab->nentries; i++) {
 150                 Identity *id = &tab->identities[i];
 151                 if (id->key->type == KEY_RSA1) {
 152                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 153                         buffer_put_bignum(&msg, id->key->rsa->e);
 154                         buffer_put_bignum(&msg, id->key->rsa->n);
 155                 } else {
 156                         u_char *blob;
 157                         u_int blen;
 158                         key_to_blob(id->key, &blob, &blen);
 159                         buffer_put_string(&msg, blob, blen);
 160                         xfree(blob);
 161                 }
 162                 buffer_put_cstring(&msg, id->comment);
 163         }
 164         buffer_put_int(&e->output, buffer_len(&msg));
 165         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 166         buffer_free(&msg);
 167 }
 168
 169 /* ssh1 only */
 170 void
 171 process_authentication_challenge1(SocketEntry *e)
 172 {
 173         Key *key, *private;
 174         BIGNUM *challenge;
 175         int i, len;
 176         Buffer msg;
 177         MD5_CTX md;
 178         u_char buf[32], mdbuf[16], session_id[16];
 179         u_int response_type;
 180
 181         buffer_init(&msg);
 182         key = key_new(KEY_RSA1);
 183         challenge = BN_new();
 184
 185         buffer_get_int(&e->input);                              /* ignored */
 186         buffer_get_bignum(&e->input, key->rsa->e);
 187         buffer_get_bignum(&e->input, key->rsa->n);
 188         buffer_get_bignum(&e->input, challenge);
 189
 190         /* Only protocol 1.1 is supported */
 191         if (buffer_len(&e->input) == 0)
 192                 goto failure;
 193         buffer_get(&e->input, (char *) session_id, 16);
 194         response_type = buffer_get_int(&e->input);
 195         if (response_type != 1)
 196                 goto failure;
 197
 198         private = lookup_private_key(key, NULL, 1);
 199         if (private != NULL) {
 200                 /* Decrypt the challenge using the private key. */
 201                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 202                         goto failure;
 203
 204                 /* The response is MD5 of decrypted challenge plus session id. */
 205                 len = BN_num_bytes(challenge);
 206                 if (len <= 0 || len > 32) {
 207                         log("process_authentication_challenge: bad challenge length %d", len);
 208                         goto failure;
 209                 }
 210                 memset(buf, 0, 32);
 211                 BN_bn2bin(challenge, buf + 32 - len);
 212                 MD5_Init(&md);
 213                 MD5_Update(&md, buf, 32);
 214                 MD5_Update(&md, session_id, 16);
 215                 MD5_Final(mdbuf, &md);
 216
 217                 /* Send the response. */
 218                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 219                 for (i = 0; i < 16; i++)
 220                         buffer_put_char(&msg, mdbuf[i]);
 221                 goto send;
 222         }
 223
 224 failure:
 225         /* Unknown identity or protocol error.  Send failure. */
 226         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 227 send:
 228         buffer_put_int(&e->output, buffer_len(&msg));
 229         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 230         key_free(key);
 231         BN_clear_free(challenge);
 232         buffer_free(&msg);
 233 }
 234
 235 /* ssh2 only */
 236 void
 237 process_sign_request2(SocketEntry *e)
 238 {
 239         extern int datafellows;
 240         Key *key, *private;
 241         u_char *blob, *data, *signature = NULL;
 242         u_int blen, dlen, slen = 0;
 243         int flags;
 244         Buffer msg;
 245         int ok = -1;
 246
 247         datafellows = 0;
 248
 249         blob = buffer_get_string(&e->input, &blen);
 250         data = buffer_get_string(&e->input, &dlen);
 251
 252         flags = buffer_get_int(&e->input);
 253         if (flags & SSH_AGENT_OLD_SIGNATURE)
 254                 datafellows = SSH_BUG_SIGBLOB;
 255
 256         key = key_from_blob(blob, blen);
 257         if (key != NULL) {
 258                 private = lookup_private_key(key, NULL, 2);
 259                 if (private != NULL)
 260                         ok = key_sign(private, &signature, &slen, data, dlen);
 261         }
 262         key_free(key);
 263         buffer_init(&msg);
 264         if (ok == 0) {
 265                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 266                 buffer_put_string(&msg, signature, slen);
 267         } else {
 268                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 269         }
 270         buffer_put_int(&e->output, buffer_len(&msg));
 271         buffer_append(&e->output, buffer_ptr(&msg),
 272             buffer_len(&msg));
 273         buffer_free(&msg);
 274         xfree(data);
 275         xfree(blob);
 276         if (signature != NULL)
 277                 xfree(signature);
 278 }
 279
 280 /* shared */
 281 void
 282 process_remove_identity(SocketEntry *e, int version)
 283 {
 284         Key *key = NULL, *private;
 285         u_char *blob;
 286         u_int blen;
 287         u_int bits;
 288         int success = 0;
 289
 290         switch(version){
 291         case 1:
 292                 key = key_new(KEY_RSA1);
 293                 bits = buffer_get_int(&e->input);
 294                 buffer_get_bignum(&e->input, key->rsa->e);
 295                 buffer_get_bignum(&e->input, key->rsa->n);
 296
 297                 if (bits != key_size(key))
 298                         log("Warning: identity keysize mismatch: actual %d, announced %d",
 299                             key_size(key), bits);
 300                 break;
 301         case 2:
 302                 blob = buffer_get_string(&e->input, &blen);
 303                 key = key_from_blob(blob, blen);
 304                 xfree(blob);
 305                 break;
 306         }
 307         if (key != NULL) {
 308                 int idx;
 309                 private = lookup_private_key(key, &idx, version);
 310                 if (private != NULL) {
 311                         /*
 312                          * We have this key.  Free the old key.  Since we
 313                          * don\'t want to leave empty slots in the middle of
 314                          * the array, we actually free the key there and move
 315                          * all the entries between the empty slot and the end
 316                          * of the array.
 317                          */
 318                         Idtab *tab = idtab_lookup(version);
 319                         key_free(tab->identities[idx].key);
 320                         xfree(tab->identities[idx].comment);
 321                         if (tab->nentries < 1)
 322                                 fatal("process_remove_identity: "
 323                                     "internal error: tab->nentries %d",
 324                                     tab->nentries);
 325                         if (idx != tab->nentries - 1) {
 326                                 int i;
 327                                 for (i = idx; i < tab->nentries - 1; i++)
 328                                         tab->identities[i] = tab->identities[i+1];
 329                         }
 330                         tab->identities[tab->nentries - 1].key = NULL;
 331                         tab->identities[tab->nentries - 1].comment = NULL;
 332                         tab->nentries--;
 333                         success = 1;
 334                 }
 335                 key_free(key);
 336         }
 337         buffer_put_int(&e->output, 1);
 338         buffer_put_char(&e->output,
 339             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 340 }
 341
 342 void
 343 process_remove_all_identities(SocketEntry *e, int version)
 344 {
 345         u_int i;
 346         Idtab *tab = idtab_lookup(version);
 347
 348         /* Loop over all identities and clear the keys. */
 349         for (i = 0; i < tab->nentries; i++) {
 350                 key_free(tab->identities[i].key);
 351                 xfree(tab->identities[i].comment);
 352         }
 353
 354         /* Mark that there are no identities. */
 355         tab->nentries = 0;
 356
 357         /* Send success. */
 358         buffer_put_int(&e->output, 1);
 359         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 360         return;
 361 }
 362
 363 void
 364 process_add_identity(SocketEntry *e, int version)
 365 {
 366         Key *k = NULL;
 367         char *type_name;
 368         char *comment;
 369         int type, success = 0;
 370         Idtab *tab = idtab_lookup(version);
 371
 372         switch (version) {
 373         case 1:
 374                 k = key_new_private(KEY_RSA1);
 375                 buffer_get_int(&e->input);                      /* ignored */
 376                 buffer_get_bignum(&e->input, k->rsa->n);
 377                 buffer_get_bignum(&e->input, k->rsa->e);
 378                 buffer_get_bignum(&e->input, k->rsa->d);
 379                 buffer_get_bignum(&e->input, k->rsa->iqmp);
 380
 381                 /* SSH and SSL have p and q swapped */
 382                 buffer_get_bignum(&e->input, k->rsa->q);        /* p */
 383                 buffer_get_bignum(&e->input, k->rsa->p);        /* q */
 384
 385                 /* Generate additional parameters */
 386                 generate_additional_parameters(k->rsa);
 387                 break;
 388         case 2:
 389                 type_name = buffer_get_string(&e->input, NULL);
 390                 type = key_type_from_name(type_name);
 391                 xfree(type_name);
 392                 switch(type) {
 393                 case KEY_DSA:
 394                         k = key_new_private(type);
 395                         buffer_get_bignum2(&e->input, k->dsa->p);
 396                         buffer_get_bignum2(&e->input, k->dsa->q);
 397                         buffer_get_bignum2(&e->input, k->dsa->g);
 398                         buffer_get_bignum2(&e->input, k->dsa->pub_key);
 399                         buffer_get_bignum2(&e->input, k->dsa->priv_key);
 400                         break;
 401                 case KEY_RSA:
 402                         k = key_new_private(type);
 403                         buffer_get_bignum2(&e->input, k->rsa->n);
 404                         buffer_get_bignum2(&e->input, k->rsa->e);
 405                         buffer_get_bignum2(&e->input, k->rsa->d);
 406                         buffer_get_bignum2(&e->input, k->rsa->iqmp);
 407                         buffer_get_bignum2(&e->input, k->rsa->p);
 408                         buffer_get_bignum2(&e->input, k->rsa->q);
 409
 410                         /* Generate additional parameters */
 411                         generate_additional_parameters(k->rsa);
 412                         break;
 413                 default:
 414                         buffer_clear(&e->input);
 415                         goto send;
 416                 }
 417                 break;
 418         }
 419         comment = buffer_get_string(&e->input, NULL);
 420         if (k == NULL) {
 421                 xfree(comment);
 422                 goto send;
 423         }
 424         success = 1;
 425         if (lookup_private_key(k, NULL, version) == NULL) {
 426                 if (tab->nentries == 0)
 427                         tab->identities = xmalloc(sizeof(Identity));
 428                 else
 429                         tab->identities = xrealloc(tab->identities,
 430                             (tab->nentries + 1) * sizeof(Identity));
 431                 tab->identities[tab->nentries].key = k;
 432                 tab->identities[tab->nentries].comment = comment;
 433                 /* Increment the number of identities. */
 434                 tab->nentries++;
 435         } else {
 436                 key_free(k);
 437                 xfree(comment);
 438         }
 439 send:
 440         buffer_put_int(&e->output, 1);
 441         buffer_put_char(&e->output,
 442             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 443 }
 444
 445 /* dispatch incoming messages */
 446
 447 void
 448 process_message(SocketEntry *e)
 449 {
 450         u_int msg_len;
 451         u_int type;
 452         u_char *cp;
 453         if (buffer_len(&e->input) < 5)
 454                 return;         /* Incomplete message. */
 455         cp = (u_char *) buffer_ptr(&e->input);
 456         msg_len = GET_32BIT(cp);
 457         if (msg_len > 256 * 1024) {
 458                 shutdown(e->fd, SHUT_RDWR);
 459                 close(e->fd);
 460                 e->type = AUTH_UNUSED;
 461                 return;
 462         }
 463         if (buffer_len(&e->input) < msg_len + 4)
 464                 return;
 465         buffer_consume(&e->input, 4);
 466         type = buffer_get_char(&e->input);
 467
 468         switch (type) {
 469         /* ssh1 */
 470         case SSH_AGENTC_RSA_CHALLENGE:
 471                 process_authentication_challenge1(e);
 472                 break;
 473         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 474                 process_request_identities(e, 1);
 475                 break;
 476         case SSH_AGENTC_ADD_RSA_IDENTITY:
 477                 process_add_identity(e, 1);
 478                 break;
 479         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 480                 process_remove_identity(e, 1);
 481                 break;
 482         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 483                 process_remove_all_identities(e, 1);
 484                 break;
 485         /* ssh2 */
 486         case SSH2_AGENTC_SIGN_REQUEST:
 487                 process_sign_request2(e);
 488                 break;
 489         case SSH2_AGENTC_REQUEST_IDENTITIES:
 490                 process_request_identities(e, 2);
 491                 break;
 492         case SSH2_AGENTC_ADD_IDENTITY:
 493                 process_add_identity(e, 2);
 494                 break;
 495         case SSH2_AGENTC_REMOVE_IDENTITY:
 496                 process_remove_identity(e, 2);
 497                 break;
 498         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 499                 process_remove_all_identities(e, 2);
 500                 break;
 501         default:
 502                 /* Unknown message.  Respond with failure. */
 503                 error("Unknown message %d", type);
 504                 buffer_clear(&e->input);
 505                 buffer_put_int(&e->output, 1);
 506                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 507                 break;
 508         }
 509 }
 510
 511 void
 512 new_socket(int type, int fd)
 513 {
 514         u_int i, old_alloc;
 515         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 516                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 517
 518         if (fd > max_fd)
 519                 max_fd = fd;
 520
 521         for (i = 0; i < sockets_alloc; i++)
 522                 if (sockets[i].type == AUTH_UNUSED) {
 523                         sockets[i].fd = fd;
 524                         sockets[i].type = type;
 525                         buffer_init(&sockets[i].input);
 526                         buffer_init(&sockets[i].output);
 527                         return;
 528                 }
 529         old_alloc = sockets_alloc;
 530         sockets_alloc += 10;
 531         if (sockets)
 532                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 533         else
 534                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 535         for (i = old_alloc; i < sockets_alloc; i++)
 536                 sockets[i].type = AUTH_UNUSED;
 537         sockets[old_alloc].type = type;
 538         sockets[old_alloc].fd = fd;
 539         buffer_init(&sockets[old_alloc].input);
 540         buffer_init(&sockets[old_alloc].output);
 541 }
 542
 543 int
 544 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl)
 545 {
 546         u_int i, sz;
 547         int n = 0;
 548
 549         for (i = 0; i < sockets_alloc; i++) {
 550                 switch (sockets[i].type) {
 551                 case AUTH_SOCKET:
 552                 case AUTH_CONNECTION:
 553                         n = MAX(n, sockets[i].fd);
 554                         break;
 555                 case AUTH_UNUSED:
 556                         break;
 557                 default:
 558                         fatal("Unknown socket type %d", sockets[i].type);
 559                         break;
 560                 }
 561         }
 562
 563         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 564         if (*fdrp == NULL || n > *fdl) {
 565                 if (*fdrp)
 566                         xfree(*fdrp);
 567                 if (*fdwp)
 568                         xfree(*fdwp);
 569                 *fdrp = xmalloc(sz);
 570                 *fdwp = xmalloc(sz);
 571                 *fdl = n;
 572         }
 573         memset(*fdrp, 0, sz);
 574         memset(*fdwp, 0, sz);
 575
 576         for (i = 0; i < sockets_alloc; i++) {
 577                 switch (sockets[i].type) {
 578                 case AUTH_SOCKET:
 579                 case AUTH_CONNECTION:
 580                         FD_SET(sockets[i].fd, *fdrp);
 581                         if (buffer_len(&sockets[i].output) > 0)
 582                                 FD_SET(sockets[i].fd, *fdwp);
 583                         break;
 584                 default:
 585                         break;
 586                 }
 587         }
 588         return (1);
 589 }
 590
 591 void
 592 after_select(fd_set *readset, fd_set *writeset)
 593 {
 594         u_int i;
 595         int len, sock;
 596         socklen_t slen;
 597         char buf[1024];
 598         struct sockaddr_un sunaddr;
 599
 600         for (i = 0; i < sockets_alloc; i++)
 601                 switch (sockets[i].type) {
 602                 case AUTH_UNUSED:
 603                         break;
 604                 case AUTH_SOCKET:
 605                         if (FD_ISSET(sockets[i].fd, readset)) {
 606                                 slen = sizeof(sunaddr);
 607                                 sock = accept(sockets[i].fd,
 608                                     (struct sockaddr *) &sunaddr, &slen);
 609                                 if (sock < 0) {
 610                                         perror("accept from AUTH_SOCKET");
 611                                         break;
 612                                 }
 613                                 new_socket(AUTH_CONNECTION, sock);
 614                         }
 615                         break;
 616                 case AUTH_CONNECTION:
 617                         if (buffer_len(&sockets[i].output) > 0 &&
 618                             FD_ISSET(sockets[i].fd, writeset)) {
 619                                 do {
 620                                         len = write(sockets[i].fd,
 621                                             buffer_ptr(&sockets[i].output),
 622                                             buffer_len(&sockets[i].output));
 623                                         if (len == -1 && (errno == EAGAIN ||
 624                                             errno == EINTR))
 625                                                 continue;
 626                                         break;
 627                                 } while (1);
 628                                 if (len <= 0) {
 629                                         shutdown(sockets[i].fd, SHUT_RDWR);
 630                                         close(sockets[i].fd);
 631                                         sockets[i].type = AUTH_UNUSED;
 632                                         buffer_free(&sockets[i].input);
 633                                         buffer_free(&sockets[i].output);
 634                                         break;
 635                                 }
 636                                 buffer_consume(&sockets[i].output, len);
 637                         }
 638                         if (FD_ISSET(sockets[i].fd, readset)) {
 639                                 do {
 640                                         len = read(sockets[i].fd, buf, sizeof(buf));
 641                                         if (len == -1 && (errno == EAGAIN ||
 642                                             errno == EINTR))
 643                                                 continue;
 644                                         break;
 645                                 } while (1);
 646                                 if (len <= 0) {
 647                                         shutdown(sockets[i].fd, SHUT_RDWR);
 648                                         close(sockets[i].fd);
 649                                         sockets[i].type = AUTH_UNUSED;
 650                                         buffer_free(&sockets[i].input);
 651                                         buffer_free(&sockets[i].output);
 652                                         break;
 653                                 }
 654                                 buffer_append(&sockets[i].input, buf, len);
 655                                 process_message(&sockets[i]);
 656                         }
 657                         break;
 658                 default:
 659                         fatal("Unknown type %d", sockets[i].type);
 660                 }
 661 }
 662
 663 void
 664 check_parent_exists(int sig)
 665 {
 666         int save_errno = errno;
 667
 668         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 669                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 670                 exit(1);
 671         }
 672         signal(SIGALRM, check_parent_exists);
 673         alarm(10);
 674         errno = save_errno;
 675 }
 676
 677 void
 678 cleanup_socket(void)
 679 {
 680         if (socket_name[0])
 681                 unlink(socket_name);
 682         if (socket_dir[0])
 683                 rmdir(socket_dir);
 684 }
 685
 686 void
 687 cleanup_exit(int i)
 688 {
 689         cleanup_socket();
 690         exit(i);
 691 }
 692
 693 void
 694 cleanup_handler(int sig)
 695 {
 696         cleanup_socket();
 697         _exit(2);
 698 }
 699
 700 void
 701 usage(void)
 702 {
 703         fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION);
 704         fprintf(stderr, "Usage: %s [-c | -s] [-k] [command {args...]]\n",
 705             __progname);
 706         exit(1);
 707 }
 708
 709 int
 710 main(int ac, char **av)
 711 {
 712         int sock, c_flag = 0, k_flag = 0, s_flag = 0, ch;
 713         struct sockaddr_un sunaddr;
 714 #ifdef HAVE_SETRLIMIT
 715         struct rlimit rlim;
 716 #endif
 717 #ifdef HAVE_CYGWIN
 718         int prev_mask;
 719 #endif
 720         pid_t pid;
 721         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 722         extern int optind;
 723         fd_set *readsetp = NULL, *writesetp = NULL;
 724
 725         SSLeay_add_all_algorithms();
 726
 727         __progname = get_progname(av[0]);
 728         init_rng();
 729         seed_rng();
 730
 731 #ifdef __GNU_LIBRARY__
 732         while ((ch = getopt(ac, av, "+cks")) != -1) {
 733 #else /* __GNU_LIBRARY__ */
 734         while ((ch = getopt(ac, av, "cks")) != -1) {
 735 #endif /* __GNU_LIBRARY__ */
 736                 switch (ch) {
 737                 case 'c':
 738                         if (s_flag)
 739                                 usage();
 740                         c_flag++;
 741                         break;
 742                 case 'k':
 743                         k_flag++;
 744                         break;
 745                 case 's':
 746                         if (c_flag)
 747                                 usage();
 748                         s_flag++;
 749                         break;
 750                 default:
 751                         usage();
 752                 }
 753         }
 754         ac -= optind;
 755         av += optind;
 756
 757         if (ac > 0 && (c_flag || k_flag || s_flag))
 758                 usage();
 759
 760         if (ac == 0 && !c_flag && !k_flag && !s_flag) {
 761                 shell = getenv("SHELL");
 762                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 763                         c_flag = 1;
 764         }
 765         if (k_flag) {
 766                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 767                 if (pidstr == NULL) {
 768                         fprintf(stderr, "%s not set, cannot kill agent\n",
 769                             SSH_AGENTPID_ENV_NAME);
 770                         exit(1);
 771                 }
 772                 pid = atoi(pidstr);
 773                 if (pid < 1) {
 774                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 775                             SSH_AGENTPID_ENV_NAME, pidstr);
 776                         exit(1);
 777                 }
 778                 if (kill(pid, SIGTERM) == -1) {
 779                         perror("kill");
 780                         exit(1);
 781                 }
 782                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 783                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 784                 printf(format, SSH_AGENTPID_ENV_NAME);
 785                 printf("echo Agent pid %d killed;\n", pid);
 786                 exit(0);
 787         }
 788         parent_pid = getpid();
 789
 790         /* Create private directory for agent socket */
 791         strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 792         if (mkdtemp(socket_dir) == NULL) {
 793                 perror("mkdtemp: private socket dir");
 794                 exit(1);
 795         }
 796         snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 797             parent_pid);
 798
 799         /*
 800          * Create socket early so it will exist before command gets run from
 801          * the parent.
 802          */
 803         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 804         if (sock < 0) {
 805                 perror("socket");
 806                 cleanup_exit(1);
 807         }
 808         memset(&sunaddr, 0, sizeof(sunaddr));
 809         sunaddr.sun_family = AF_UNIX;
 810         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 811 #ifdef HAVE_CYGWIN
 812         prev_mask = umask(0177);
 813 #endif
 814         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 815                 perror("bind");
 816 #ifdef HAVE_CYGWIN
 817                 umask(prev_mask);
 818 #endif
 819                 cleanup_exit(1);
 820         }
 821 #ifdef HAVE_CYGWIN
 822         umask(prev_mask);
 823 #endif
 824         if (listen(sock, 5) < 0) {
 825                 perror("listen");
 826                 cleanup_exit(1);
 827         }
 828
 829         /*
 830          * Fork, and have the parent execute the command, if any, or present
 831          * the socket data.  The child continues as the authentication agent.
 832          */
 833         pid = fork();
 834         if (pid == -1) {
 835                 perror("fork");
 836                 exit(1);
 837         }
 838         if (pid != 0) {         /* Parent - execute the given command. */
 839                 close(sock);
 840                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 841                 if (ac == 0) {
 842                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 843                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 844                             SSH_AUTHSOCKET_ENV_NAME);
 845                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 846                             SSH_AGENTPID_ENV_NAME);
 847                         printf("echo Agent pid %d;\n", pid);
 848                         exit(0);
 849                 }
 850                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 851                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 852                         perror("setenv");
 853                         exit(1);
 854                 }
 855                 execvp(av[0], av);
 856                 perror(av[0]);
 857                 exit(1);
 858         }
 859         close(0);
 860         close(1);
 861         close(2);
 862
 863 #ifdef HAVE_SETRLIMIT
 864         /* deny core dumps, since memory contains unencrypted private keys */
 865         rlim.rlim_cur = rlim.rlim_max = 0;
 866         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
 867                 perror("setrlimit rlimit_core failed");
 868                 cleanup_exit(1);
 869         }
 870 #endif
 871         if (setsid() == -1) {
 872                 perror("setsid");
 873                 cleanup_exit(1);
 874         }
 875         if (atexit(cleanup_socket) < 0) {
 876                 perror("atexit");
 877                 cleanup_exit(1);
 878         }
 879         new_socket(AUTH_SOCKET, sock);
 880         if (ac > 0) {
 881                 signal(SIGALRM, check_parent_exists);
 882                 alarm(10);
 883         }
 884         idtab_init();
 885         signal(SIGINT, SIG_IGN);
 886         signal(SIGPIPE, SIG_IGN);
 887         signal(SIGHUP, cleanup_handler);
 888         signal(SIGTERM, cleanup_handler);
 889         while (1) {
 890                 prepare_select(&readsetp, &writesetp, &max_fd);
 891                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
 892                         if (errno == EINTR)
 893                                 continue;
 894                         exit(1);
 895                 }
 896                 after_select(readsetp, writesetp);
 897         }
 898         /* NOTREACHED */
 899 }