ssh-agent.c

   1 /*      $OpenBSD: ssh-agent.c,v 1.56 2001/06/25 08:25:40 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  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  16  *
  17  * Redistribution and use in source and binary forms, with or without
  18  * modification, are permitted provided that the following conditions
  19  * are met:
  20  * 1. Redistributions of source code must retain the above copyright
  21  *    notice, this list of conditions and the following disclaimer.
  22  * 2. Redistributions in binary form must reproduce the above copyright
  23  *    notice, this list of conditions and the following disclaimer in the
  24  *    documentation and/or other materials provided with the distribution.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  27  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  29  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  30  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  31  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  35  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  */
  37
  38 #include "includes.h"
  39 RCSID("$OpenBSD: ssh-agent.c,v 1.56 2001/06/25 08:25:40 markus Exp $");
  40
  41 #include <openssl/evp.h>
  42 #include <openssl/md5.h>
  43
  44 #include "ssh.h"
  45 #include "rsa.h"
  46 #include "buffer.h"
  47 #include "bufaux.h"
  48 #include "xmalloc.h"
  49 #include "packet.h"
  50 #include "getput.h"
  51 #include "mpaux.h"
  52 #include "key.h"
  53 #include "authfd.h"
  54 #include "cipher.h"
  55 #include "kex.h"
  56 #include "compat.h"
  57 #include "log.h"
  58
  59 typedef struct {
  60         int fd;
  61         enum {
  62                 AUTH_UNUSED, AUTH_SOCKET, AUTH_CONNECTION
  63         } type;
  64         Buffer input;
  65         Buffer output;
  66 } SocketEntry;
  67
  68 u_int sockets_alloc = 0;
  69 SocketEntry *sockets = NULL;
  70
  71 typedef struct {
  72         Key *key;
  73         char *comment;
  74 } Identity;
  75
  76 typedef struct {
  77         int nentries;
  78         Identity *identities;
  79 } Idtab;
  80
  81 /* private key table, one per protocol version */
  82 Idtab idtable[3];
  83
  84 int max_fd = 0;
  85
  86 /* pid of shell == parent of agent */
  87 pid_t parent_pid = -1;
  88
  89 /* pathname and directory for AUTH_SOCKET */
  90 char socket_name[1024];
  91 char socket_dir[1024];
  92
  93 #ifdef HAVE___PROGNAME
  94 extern char *__progname;
  95 #else
  96 char *__progname;
  97 #endif
  98
  99 static void
 100 idtab_init(void)
 101 {
 102         int i;
 103         for (i = 0; i <=2; i++){
 104                 idtable[i].identities = NULL;
 105                 idtable[i].nentries = 0;
 106         }
 107 }
 108
 109 /* return private key table for requested protocol version */
 110 static Idtab *
 111 idtab_lookup(int version)
 112 {
 113         if (version < 1 || version > 2)
 114                 fatal("internal error, bad protocol version %d", version);
 115         return &idtable[version];
 116 }
 117
 118 /* return matching private key for given public key */
 119 static Key *
 120 lookup_private_key(Key *key, int *idx, int version)
 121 {
 122         int i;
 123         Idtab *tab = idtab_lookup(version);
 124         for (i = 0; i < tab->nentries; i++) {
 125                 if (key_equal(key, tab->identities[i].key)) {
 126                         if (idx != NULL)
 127                                 *idx = i;
 128                         return tab->identities[i].key;
 129                 }
 130         }
 131         return NULL;
 132 }
 133
 134 /* send list of supported public keys to 'client' */
 135 static void
 136 process_request_identities(SocketEntry *e, int version)
 137 {
 138         Idtab *tab = idtab_lookup(version);
 139         Buffer msg;
 140         int i;
 141
 142         buffer_init(&msg);
 143         buffer_put_char(&msg, (version == 1) ?
 144             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 145         buffer_put_int(&msg, tab->nentries);
 146         for (i = 0; i < tab->nentries; i++) {
 147                 Identity *id = &tab->identities[i];
 148                 if (id->key->type == KEY_RSA1) {
 149                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 150                         buffer_put_bignum(&msg, id->key->rsa->e);
 151                         buffer_put_bignum(&msg, id->key->rsa->n);
 152                 } else {
 153                         u_char *blob;
 154                         u_int blen;
 155                         key_to_blob(id->key, &blob, &blen);
 156                         buffer_put_string(&msg, blob, blen);
 157                         xfree(blob);
 158                 }
 159                 buffer_put_cstring(&msg, id->comment);
 160         }
 161         buffer_put_int(&e->output, buffer_len(&msg));
 162         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 163         buffer_free(&msg);
 164 }
 165
 166 /* ssh1 only */
 167 static void
 168 process_authentication_challenge1(SocketEntry *e)
 169 {
 170         Key *key, *private;
 171         BIGNUM *challenge;
 172         int i, len;
 173         Buffer msg;
 174         MD5_CTX md;
 175         u_char buf[32], mdbuf[16], session_id[16];
 176         u_int response_type;
 177
 178         buffer_init(&msg);
 179         key = key_new(KEY_RSA1);
 180         challenge = BN_new();
 181
 182         buffer_get_int(&e->input);                              /* ignored */
 183         buffer_get_bignum(&e->input, key->rsa->e);
 184         buffer_get_bignum(&e->input, key->rsa->n);
 185         buffer_get_bignum(&e->input, challenge);
 186
 187         /* Only protocol 1.1 is supported */
 188         if (buffer_len(&e->input) == 0)
 189                 goto failure;
 190         buffer_get(&e->input, (char *) session_id, 16);
 191         response_type = buffer_get_int(&e->input);
 192         if (response_type != 1)
 193                 goto failure;
 194
 195         private = lookup_private_key(key, NULL, 1);
 196         if (private != NULL) {
 197                 /* Decrypt the challenge using the private key. */
 198                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 199                         goto failure;
 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 static void
 234 process_sign_request2(SocketEntry *e)
 235 {
 236         extern int datafellows;
 237         Key *key, *private;
 238         u_char *blob, *data, *signature = NULL;
 239         u_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 static void
 279 process_remove_identity(SocketEntry *e, int version)
 280 {
 281         Key *key = NULL, *private;
 282         u_char *blob;
 283         u_int blen;
 284         u_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 static void
 340 process_remove_all_identities(SocketEntry *e, int version)
 341 {
 342         u_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 static void
 361 process_add_identity(SocketEntry *e, int version)
 362 {
 363         Key *k = NULL;
 364         char *type_name;
 365         char *comment;
 366         int type, success = 0;
 367         Idtab *tab = idtab_lookup(version);
 368
 369         switch (version) {
 370         case 1:
 371                 k = key_new_private(KEY_RSA1);
 372                 buffer_get_int(&e->input);                      /* ignored */
 373                 buffer_get_bignum(&e->input, k->rsa->n);
 374                 buffer_get_bignum(&e->input, k->rsa->e);
 375                 buffer_get_bignum(&e->input, k->rsa->d);
 376                 buffer_get_bignum(&e->input, k->rsa->iqmp);
 377
 378                 /* SSH and SSL have p and q swapped */
 379                 buffer_get_bignum(&e->input, k->rsa->q);        /* p */
 380                 buffer_get_bignum(&e->input, k->rsa->p);        /* q */
 381
 382                 /* Generate additional parameters */
 383                 generate_additional_parameters(k->rsa);
 384                 break;
 385         case 2:
 386                 type_name = buffer_get_string(&e->input, NULL);
 387                 type = key_type_from_name(type_name);
 388                 xfree(type_name);
 389                 switch(type) {
 390                 case KEY_DSA:
 391                         k = key_new_private(type);
 392                         buffer_get_bignum2(&e->input, k->dsa->p);
 393                         buffer_get_bignum2(&e->input, k->dsa->q);
 394                         buffer_get_bignum2(&e->input, k->dsa->g);
 395                         buffer_get_bignum2(&e->input, k->dsa->pub_key);
 396                         buffer_get_bignum2(&e->input, k->dsa->priv_key);
 397                         break;
 398                 case KEY_RSA:
 399                         k = key_new_private(type);
 400                         buffer_get_bignum2(&e->input, k->rsa->n);
 401                         buffer_get_bignum2(&e->input, k->rsa->e);
 402                         buffer_get_bignum2(&e->input, k->rsa->d);
 403                         buffer_get_bignum2(&e->input, k->rsa->iqmp);
 404                         buffer_get_bignum2(&e->input, k->rsa->p);
 405                         buffer_get_bignum2(&e->input, k->rsa->q);
 406
 407                         /* Generate additional parameters */
 408                         generate_additional_parameters(k->rsa);
 409                         break;
 410                 default:
 411                         buffer_clear(&e->input);
 412                         goto send;
 413                 }
 414                 break;
 415         }
 416         comment = buffer_get_string(&e->input, NULL);
 417         if (k == NULL) {
 418                 xfree(comment);
 419                 goto send;
 420         }
 421         success = 1;
 422         if (lookup_private_key(k, NULL, version) == NULL) {
 423                 if (tab->nentries == 0)
 424                         tab->identities = xmalloc(sizeof(Identity));
 425                 else
 426                         tab->identities = xrealloc(tab->identities,
 427                             (tab->nentries + 1) * sizeof(Identity));
 428                 tab->identities[tab->nentries].key = k;
 429                 tab->identities[tab->nentries].comment = comment;
 430                 /* Increment the number of identities. */
 431                 tab->nentries++;
 432         } else {
 433                 key_free(k);
 434                 xfree(comment);
 435         }
 436 send:
 437         buffer_put_int(&e->output, 1);
 438         buffer_put_char(&e->output,
 439             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 440 }
 441
 442 /* dispatch incoming messages */
 443
 444 static void
 445 process_message(SocketEntry *e)
 446 {
 447         u_int msg_len;
 448         u_int type;
 449         u_char *cp;
 450         if (buffer_len(&e->input) < 5)
 451                 return;         /* Incomplete message. */
 452         cp = (u_char *) buffer_ptr(&e->input);
 453         msg_len = GET_32BIT(cp);
 454         if (msg_len > 256 * 1024) {
 455                 shutdown(e->fd, SHUT_RDWR);
 456                 close(e->fd);
 457                 e->type = AUTH_UNUSED;
 458                 return;
 459         }
 460         if (buffer_len(&e->input) < msg_len + 4)
 461                 return;
 462         buffer_consume(&e->input, 4);
 463         type = buffer_get_char(&e->input);
 464
 465         switch (type) {
 466         /* ssh1 */
 467         case SSH_AGENTC_RSA_CHALLENGE:
 468                 process_authentication_challenge1(e);
 469                 break;
 470         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 471                 process_request_identities(e, 1);
 472                 break;
 473         case SSH_AGENTC_ADD_RSA_IDENTITY:
 474                 process_add_identity(e, 1);
 475                 break;
 476         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 477                 process_remove_identity(e, 1);
 478                 break;
 479         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 480                 process_remove_all_identities(e, 1);
 481                 break;
 482         /* ssh2 */
 483         case SSH2_AGENTC_SIGN_REQUEST:
 484                 process_sign_request2(e);
 485                 break;
 486         case SSH2_AGENTC_REQUEST_IDENTITIES:
 487                 process_request_identities(e, 2);
 488                 break;
 489         case SSH2_AGENTC_ADD_IDENTITY:
 490                 process_add_identity(e, 2);
 491                 break;
 492         case SSH2_AGENTC_REMOVE_IDENTITY:
 493                 process_remove_identity(e, 2);
 494                 break;
 495         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 496                 process_remove_all_identities(e, 2);
 497                 break;
 498         default:
 499                 /* Unknown message.  Respond with failure. */
 500                 error("Unknown message %d", type);
 501                 buffer_clear(&e->input);
 502                 buffer_put_int(&e->output, 1);
 503                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 504                 break;
 505         }
 506 }
 507
 508 static void
 509 new_socket(int type, int fd)
 510 {
 511         u_int i, old_alloc;
 512         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 513                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 514
 515         if (fd > max_fd)
 516                 max_fd = fd;
 517
 518         for (i = 0; i < sockets_alloc; i++)
 519                 if (sockets[i].type == AUTH_UNUSED) {
 520                         sockets[i].fd = fd;
 521                         sockets[i].type = type;
 522                         buffer_init(&sockets[i].input);
 523                         buffer_init(&sockets[i].output);
 524                         return;
 525                 }
 526         old_alloc = sockets_alloc;
 527         sockets_alloc += 10;
 528         if (sockets)
 529                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 530         else
 531                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 532         for (i = old_alloc; i < sockets_alloc; i++)
 533                 sockets[i].type = AUTH_UNUSED;
 534         sockets[old_alloc].type = type;
 535         sockets[old_alloc].fd = fd;
 536         buffer_init(&sockets[old_alloc].input);
 537         buffer_init(&sockets[old_alloc].output);
 538 }
 539
 540 static int
 541 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl)
 542 {
 543         u_int i, sz;
 544         int n = 0;
 545
 546         for (i = 0; i < sockets_alloc; i++) {
 547                 switch (sockets[i].type) {
 548                 case AUTH_SOCKET:
 549                 case AUTH_CONNECTION:
 550                         n = MAX(n, sockets[i].fd);
 551                         break;
 552                 case AUTH_UNUSED:
 553                         break;
 554                 default:
 555                         fatal("Unknown socket type %d", sockets[i].type);
 556                         break;
 557                 }
 558         }
 559
 560         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 561         if (*fdrp == NULL || n > *fdl) {
 562                 if (*fdrp)
 563                         xfree(*fdrp);
 564                 if (*fdwp)
 565                         xfree(*fdwp);
 566                 *fdrp = xmalloc(sz);
 567                 *fdwp = xmalloc(sz);
 568                 *fdl = n;
 569         }
 570         memset(*fdrp, 0, sz);
 571         memset(*fdwp, 0, sz);
 572
 573         for (i = 0; i < sockets_alloc; i++) {
 574                 switch (sockets[i].type) {
 575                 case AUTH_SOCKET:
 576                 case AUTH_CONNECTION:
 577                         FD_SET(sockets[i].fd, *fdrp);
 578                         if (buffer_len(&sockets[i].output) > 0)
 579                                 FD_SET(sockets[i].fd, *fdwp);
 580                         break;
 581                 default:
 582                         break;
 583                 }
 584         }
 585         return (1);
 586 }
 587
 588 static void
 589 after_select(fd_set *readset, fd_set *writeset)
 590 {
 591         u_int i;
 592         int len, sock;
 593         socklen_t slen;
 594         char buf[1024];
 595         struct sockaddr_un sunaddr;
 596
 597         for (i = 0; i < sockets_alloc; i++)
 598                 switch (sockets[i].type) {
 599                 case AUTH_UNUSED:
 600                         break;
 601                 case AUTH_SOCKET:
 602                         if (FD_ISSET(sockets[i].fd, readset)) {
 603                                 slen = sizeof(sunaddr);
 604                                 sock = accept(sockets[i].fd,
 605                                     (struct sockaddr *) &sunaddr, &slen);
 606                                 if (sock < 0) {
 607                                         perror("accept from AUTH_SOCKET");
 608                                         break;
 609                                 }
 610                                 new_socket(AUTH_CONNECTION, sock);
 611                         }
 612                         break;
 613                 case AUTH_CONNECTION:
 614                         if (buffer_len(&sockets[i].output) > 0 &&
 615                             FD_ISSET(sockets[i].fd, writeset)) {
 616                                 do {
 617                                         len = write(sockets[i].fd,
 618                                             buffer_ptr(&sockets[i].output),
 619                                             buffer_len(&sockets[i].output));
 620                                         if (len == -1 && (errno == EAGAIN ||
 621                                             errno == EINTR))
 622                                                 continue;
 623                                         break;
 624                                 } while (1);
 625                                 if (len <= 0) {
 626                                         shutdown(sockets[i].fd, SHUT_RDWR);
 627                                         close(sockets[i].fd);
 628                                         sockets[i].type = AUTH_UNUSED;
 629                                         buffer_free(&sockets[i].input);
 630                                         buffer_free(&sockets[i].output);
 631                                         break;
 632                                 }
 633                                 buffer_consume(&sockets[i].output, len);
 634                         }
 635                         if (FD_ISSET(sockets[i].fd, readset)) {
 636                                 do {
 637                                         len = read(sockets[i].fd, buf, sizeof(buf));
 638                                         if (len == -1 && (errno == EAGAIN ||
 639                                             errno == EINTR))
 640                                                 continue;
 641                                         break;
 642                                 } while (1);
 643                                 if (len <= 0) {
 644                                         shutdown(sockets[i].fd, SHUT_RDWR);
 645                                         close(sockets[i].fd);
 646                                         sockets[i].type = AUTH_UNUSED;
 647                                         buffer_free(&sockets[i].input);
 648                                         buffer_free(&sockets[i].output);
 649                                         break;
 650                                 }
 651                                 buffer_append(&sockets[i].input, buf, len);
 652                                 process_message(&sockets[i]);
 653                         }
 654                         break;
 655                 default:
 656                         fatal("Unknown type %d", sockets[i].type);
 657                 }
 658 }
 659
 660 static void
 661 check_parent_exists(int sig)
 662 {
 663         int save_errno = errno;
 664
 665         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 666                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 667                 exit(1);
 668         }
 669         signal(SIGALRM, check_parent_exists);
 670         alarm(10);
 671         errno = save_errno;
 672 }
 673
 674 static void
 675 cleanup_socket(void)
 676 {
 677         if (socket_name[0])
 678                 unlink(socket_name);
 679         if (socket_dir[0])
 680                 rmdir(socket_dir);
 681 }
 682
 683 static void
 684 cleanup_exit(int i)
 685 {
 686         cleanup_socket();
 687         exit(i);
 688 }
 689
 690 static void
 691 cleanup_handler(int sig)
 692 {
 693         cleanup_socket();
 694         _exit(2);
 695 }
 696
 697 static void
 698 usage(void)
 699 {
 700         fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION);
 701         fprintf(stderr, "Usage: %s [-c | -s] [-k] [command {args...]]\n",
 702             __progname);
 703         exit(1);
 704 }
 705
 706 int
 707 main(int ac, char **av)
 708 {
 709         int sock, c_flag = 0, k_flag = 0, s_flag = 0, ch;
 710         struct sockaddr_un sunaddr;
 711 #ifdef HAVE_SETRLIMIT
 712         struct rlimit rlim;
 713 #endif
 714 #ifdef HAVE_CYGWIN
 715         int prev_mask;
 716 #endif
 717         pid_t pid;
 718         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 719         extern int optind;
 720         fd_set *readsetp = NULL, *writesetp = NULL;
 721
 722         SSLeay_add_all_algorithms();
 723
 724         __progname = get_progname(av[0]);
 725         init_rng();
 726         seed_rng();
 727
 728 #ifdef __GNU_LIBRARY__
 729         while ((ch = getopt(ac, av, "+cks")) != -1) {
 730 #else /* __GNU_LIBRARY__ */
 731         while ((ch = getopt(ac, av, "cks")) != -1) {
 732 #endif /* __GNU_LIBRARY__ */
 733                 switch (ch) {
 734                 case 'c':
 735                         if (s_flag)
 736                                 usage();
 737                         c_flag++;
 738                         break;
 739                 case 'k':
 740                         k_flag++;
 741                         break;
 742                 case 's':
 743                         if (c_flag)
 744                                 usage();
 745                         s_flag++;
 746                         break;
 747                 default:
 748                         usage();
 749                 }
 750         }
 751         ac -= optind;
 752         av += optind;
 753
 754         if (ac > 0 && (c_flag || k_flag || s_flag))
 755                 usage();
 756
 757         if (ac == 0 && !c_flag && !k_flag && !s_flag) {
 758                 shell = getenv("SHELL");
 759                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 760                         c_flag = 1;
 761         }
 762         if (k_flag) {
 763                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 764                 if (pidstr == NULL) {
 765                         fprintf(stderr, "%s not set, cannot kill agent\n",
 766                             SSH_AGENTPID_ENV_NAME);
 767                         exit(1);
 768                 }
 769                 pid = atoi(pidstr);
 770                 if (pid < 1) {
 771                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 772                             SSH_AGENTPID_ENV_NAME, pidstr);
 773                         exit(1);
 774                 }
 775                 if (kill(pid, SIGTERM) == -1) {
 776                         perror("kill");
 777                         exit(1);
 778                 }
 779                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 780                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 781                 printf(format, SSH_AGENTPID_ENV_NAME);
 782                 printf("echo Agent pid %d killed;\n", pid);
 783                 exit(0);
 784         }
 785         parent_pid = getpid();
 786
 787         /* Create private directory for agent socket */
 788         strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 789         if (mkdtemp(socket_dir) == NULL) {
 790                 perror("mkdtemp: private socket dir");
 791                 exit(1);
 792         }
 793         snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 794             parent_pid);
 795
 796         /*
 797          * Create socket early so it will exist before command gets run from
 798          * the parent.
 799          */
 800         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 801         if (sock < 0) {
 802                 perror("socket");
 803                 cleanup_exit(1);
 804         }
 805         memset(&sunaddr, 0, sizeof(sunaddr));
 806         sunaddr.sun_family = AF_UNIX;
 807         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 808 #ifdef HAVE_CYGWIN
 809         prev_mask = umask(0177);
 810 #endif
 811         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 812                 perror("bind");
 813 #ifdef HAVE_CYGWIN
 814                 umask(prev_mask);
 815 #endif
 816                 cleanup_exit(1);
 817         }
 818 #ifdef HAVE_CYGWIN
 819         umask(prev_mask);
 820 #endif
 821         if (listen(sock, 5) < 0) {
 822                 perror("listen");
 823                 cleanup_exit(1);
 824         }
 825
 826         /*
 827          * Fork, and have the parent execute the command, if any, or present
 828          * the socket data.  The child continues as the authentication agent.
 829          */
 830         pid = fork();
 831         if (pid == -1) {
 832                 perror("fork");
 833                 exit(1);
 834         }
 835         if (pid != 0) {         /* Parent - execute the given command. */
 836                 close(sock);
 837                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 838                 if (ac == 0) {
 839                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 840                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 841                             SSH_AUTHSOCKET_ENV_NAME);
 842                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 843                             SSH_AGENTPID_ENV_NAME);
 844                         printf("echo Agent pid %d;\n", pid);
 845                         exit(0);
 846                 }
 847                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 848                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 849                         perror("setenv");
 850                         exit(1);
 851                 }
 852                 execvp(av[0], av);
 853                 perror(av[0]);
 854                 exit(1);
 855         }
 856         close(0);
 857         close(1);
 858         close(2);
 859
 860 #ifdef HAVE_SETRLIMIT
 861         /* deny core dumps, since memory contains unencrypted private keys */
 862         rlim.rlim_cur = rlim.rlim_max = 0;
 863         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
 864                 perror("setrlimit rlimit_core failed");
 865                 cleanup_exit(1);
 866         }
 867 #endif
 868         if (setsid() == -1) {
 869                 perror("setsid");
 870                 cleanup_exit(1);
 871         }
 872         if (atexit(cleanup_socket) < 0) {
 873                 perror("atexit");
 874                 cleanup_exit(1);
 875         }
 876         new_socket(AUTH_SOCKET, sock);
 877         if (ac > 0) {
 878                 signal(SIGALRM, check_parent_exists);
 879                 alarm(10);
 880         }
 881         idtab_init();
 882         signal(SIGINT, SIG_IGN);
 883         signal(SIGPIPE, SIG_IGN);
 884         signal(SIGHUP, cleanup_handler);
 885         signal(SIGTERM, cleanup_handler);
 886         while (1) {
 887                 prepare_select(&readsetp, &writesetp, &max_fd);
 888                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
 889                         if (errno == EINTR)
 890                                 continue;
 891                         exit(1);
 892                 }
 893                 after_select(readsetp, writesetp);
 894         }
 895         /* NOTREACHED */
 896 }