ssh-agent.c

   1 /*      $OpenBSD: ssh-agent.c,v 1.66 2001/07/17 20:48:42 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 1.66 2001/07/17 20:48:42 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 #ifdef SMARTCARD
  60 #include <openssl/engine.h>
  61 #include "scard.h"
  62 #endif
  63
  64 typedef struct {
  65         int fd;
  66         enum {
  67                 AUTH_UNUSED, AUTH_SOCKET, AUTH_CONNECTION
  68         } type;
  69         Buffer input;
  70         Buffer output;
  71 } SocketEntry;
  72
  73 u_int sockets_alloc = 0;
  74 SocketEntry *sockets = NULL;
  75
  76 typedef struct {
  77         Key *key;
  78         char *comment;
  79 } Identity;
  80
  81 typedef struct {
  82         int nentries;
  83         Identity *identities;
  84 } Idtab;
  85
  86 /* private key table, one per protocol version */
  87 Idtab idtable[3];
  88
  89 int max_fd = 0;
  90
  91 /* pid of shell == parent of agent */
  92 pid_t parent_pid = -1;
  93
  94 /* pathname and directory for AUTH_SOCKET */
  95 char socket_name[1024];
  96 char socket_dir[1024];
  97
  98 #ifdef HAVE___PROGNAME
  99 extern char *__progname;
 100 #else
 101 char *__progname;
 102 #endif
 103
 104 static void
 105 idtab_init(void)
 106 {
 107         int i;
 108         for (i = 0; i <=2; i++){
 109                 idtable[i].identities = NULL;
 110                 idtable[i].nentries = 0;
 111         }
 112 }
 113
 114 /* return private key table for requested protocol version */
 115 static Idtab *
 116 idtab_lookup(int version)
 117 {
 118         if (version < 1 || version > 2)
 119                 fatal("internal error, bad protocol version %d", version);
 120         return &idtable[version];
 121 }
 122
 123 /* return matching private key for given public key */
 124 static Key *
 125 lookup_private_key(Key *key, int *idx, int version)
 126 {
 127         int i;
 128         Idtab *tab = idtab_lookup(version);
 129         for (i = 0; i < tab->nentries; i++) {
 130                 if (key_equal(key, tab->identities[i].key)) {
 131                         if (idx != NULL)
 132                                 *idx = i;
 133                         return tab->identities[i].key;
 134                 }
 135         }
 136         return NULL;
 137 }
 138
 139 /* send list of supported public keys to 'client' */
 140 static void
 141 process_request_identities(SocketEntry *e, int version)
 142 {
 143         Idtab *tab = idtab_lookup(version);
 144         Buffer msg;
 145         int i;
 146
 147         buffer_init(&msg);
 148         buffer_put_char(&msg, (version == 1) ?
 149             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 150         buffer_put_int(&msg, tab->nentries);
 151         for (i = 0; i < tab->nentries; i++) {
 152                 Identity *id = &tab->identities[i];
 153                 if (id->key->type == KEY_RSA1) {
 154                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 155                         buffer_put_bignum(&msg, id->key->rsa->e);
 156                         buffer_put_bignum(&msg, id->key->rsa->n);
 157                 } else {
 158                         u_char *blob;
 159                         u_int blen;
 160                         key_to_blob(id->key, &blob, &blen);
 161                         buffer_put_string(&msg, blob, blen);
 162                         xfree(blob);
 163                 }
 164                 buffer_put_cstring(&msg, id->comment);
 165         }
 166         buffer_put_int(&e->output, buffer_len(&msg));
 167         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 168         buffer_free(&msg);
 169 }
 170
 171 /* ssh1 only */
 172 static void
 173 process_authentication_challenge1(SocketEntry *e)
 174 {
 175         Key *key, *private;
 176         BIGNUM *challenge;
 177         int i, len;
 178         Buffer msg;
 179         MD5_CTX md;
 180         u_char buf[32], mdbuf[16], session_id[16];
 181         u_int response_type;
 182
 183         buffer_init(&msg);
 184         key = key_new(KEY_RSA1);
 185         challenge = BN_new();
 186
 187         buffer_get_int(&e->input);                              /* ignored */
 188         buffer_get_bignum(&e->input, key->rsa->e);
 189         buffer_get_bignum(&e->input, key->rsa->n);
 190         buffer_get_bignum(&e->input, challenge);
 191
 192         /* Only protocol 1.1 is supported */
 193         if (buffer_len(&e->input) == 0)
 194                 goto failure;
 195         buffer_get(&e->input, (char *) session_id, 16);
 196         response_type = buffer_get_int(&e->input);
 197         if (response_type != 1)
 198                 goto failure;
 199
 200         private = lookup_private_key(key, NULL, 1);
 201         if (private != NULL) {
 202                 /* Decrypt the challenge using the private key. */
 203                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 204                         goto failure;
 205
 206                 /* The response is MD5 of decrypted challenge plus session id. */
 207                 len = BN_num_bytes(challenge);
 208                 if (len <= 0 || len > 32) {
 209                         log("process_authentication_challenge: bad challenge length %d", len);
 210                         goto failure;
 211                 }
 212                 memset(buf, 0, 32);
 213                 BN_bn2bin(challenge, buf + 32 - len);
 214                 MD5_Init(&md);
 215                 MD5_Update(&md, buf, 32);
 216                 MD5_Update(&md, session_id, 16);
 217                 MD5_Final(mdbuf, &md);
 218
 219                 /* Send the response. */
 220                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 221                 for (i = 0; i < 16; i++)
 222                         buffer_put_char(&msg, mdbuf[i]);
 223                 goto send;
 224         }
 225
 226 failure:
 227         /* Unknown identity or protocol error.  Send failure. */
 228         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 229 send:
 230         buffer_put_int(&e->output, buffer_len(&msg));
 231         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 232         key_free(key);
 233         BN_clear_free(challenge);
 234         buffer_free(&msg);
 235 }
 236
 237 /* ssh2 only */
 238 static void
 239 process_sign_request2(SocketEntry *e)
 240 {
 241         extern int datafellows;
 242         Key *key, *private;
 243         u_char *blob, *data, *signature = NULL;
 244         u_int blen, dlen, slen = 0;
 245         int flags;
 246         Buffer msg;
 247         int ok = -1;
 248
 249         datafellows = 0;
 250
 251         blob = buffer_get_string(&e->input, &blen);
 252         data = buffer_get_string(&e->input, &dlen);
 253
 254         flags = buffer_get_int(&e->input);
 255         if (flags & SSH_AGENT_OLD_SIGNATURE)
 256                 datafellows = SSH_BUG_SIGBLOB;
 257
 258         key = key_from_blob(blob, blen);
 259         if (key != NULL) {
 260                 private = lookup_private_key(key, NULL, 2);
 261                 if (private != NULL)
 262                         ok = key_sign(private, &signature, &slen, data, dlen);
 263         }
 264         key_free(key);
 265         buffer_init(&msg);
 266         if (ok == 0) {
 267                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 268                 buffer_put_string(&msg, signature, slen);
 269         } else {
 270                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 271         }
 272         buffer_put_int(&e->output, buffer_len(&msg));
 273         buffer_append(&e->output, buffer_ptr(&msg),
 274             buffer_len(&msg));
 275         buffer_free(&msg);
 276         xfree(data);
 277         xfree(blob);
 278         if (signature != NULL)
 279                 xfree(signature);
 280 }
 281
 282 /* shared */
 283 static void
 284 process_remove_identity(SocketEntry *e, int version)
 285 {
 286         Key *key = NULL, *private;
 287         u_char *blob;
 288         u_int blen;
 289         u_int bits;
 290         int success = 0;
 291
 292         switch(version){
 293         case 1:
 294                 key = key_new(KEY_RSA1);
 295                 bits = buffer_get_int(&e->input);
 296                 buffer_get_bignum(&e->input, key->rsa->e);
 297                 buffer_get_bignum(&e->input, key->rsa->n);
 298
 299                 if (bits != key_size(key))
 300                         log("Warning: identity keysize mismatch: actual %d, announced %d",
 301                             key_size(key), bits);
 302                 break;
 303         case 2:
 304                 blob = buffer_get_string(&e->input, &blen);
 305                 key = key_from_blob(blob, blen);
 306                 xfree(blob);
 307                 break;
 308         }
 309         if (key != NULL) {
 310                 int idx;
 311                 private = lookup_private_key(key, &idx, version);
 312                 if (private != NULL) {
 313                         /*
 314                          * We have this key.  Free the old key.  Since we
 315                          * don\'t want to leave empty slots in the middle of
 316                          * the array, we actually free the key there and move
 317                          * all the entries between the empty slot and the end
 318                          * of the array.
 319                          */
 320                         Idtab *tab = idtab_lookup(version);
 321                         key_free(tab->identities[idx].key);
 322                         xfree(tab->identities[idx].comment);
 323                         if (tab->nentries < 1)
 324                                 fatal("process_remove_identity: "
 325                                     "internal error: tab->nentries %d",
 326                                     tab->nentries);
 327                         if (idx != tab->nentries - 1) {
 328                                 int i;
 329                                 for (i = idx; i < tab->nentries - 1; i++)
 330                                         tab->identities[i] = tab->identities[i+1];
 331                         }
 332                         tab->identities[tab->nentries - 1].key = NULL;
 333                         tab->identities[tab->nentries - 1].comment = NULL;
 334                         tab->nentries--;
 335                         success = 1;
 336                 }
 337                 key_free(key);
 338         }
 339         buffer_put_int(&e->output, 1);
 340         buffer_put_char(&e->output,
 341             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 342 }
 343
 344 static void
 345 process_remove_all_identities(SocketEntry *e, int version)
 346 {
 347         u_int i;
 348         Idtab *tab = idtab_lookup(version);
 349
 350         /* Loop over all identities and clear the keys. */
 351         for (i = 0; i < tab->nentries; i++) {
 352                 key_free(tab->identities[i].key);
 353                 xfree(tab->identities[i].comment);
 354         }
 355
 356         /* Mark that there are no identities. */
 357         tab->nentries = 0;
 358
 359         /* Send success. */
 360         buffer_put_int(&e->output, 1);
 361         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 362         return;
 363 }
 364
 365 static void
 366 process_add_identity(SocketEntry *e, int version)
 367 {
 368         Key *k = NULL;
 369         char *type_name;
 370         char *comment;
 371         int type, success = 0;
 372         Idtab *tab = idtab_lookup(version);
 373
 374         switch (version) {
 375         case 1:
 376                 k = key_new_private(KEY_RSA1);
 377                 buffer_get_int(&e->input);                      /* ignored */
 378                 buffer_get_bignum(&e->input, k->rsa->n);
 379                 buffer_get_bignum(&e->input, k->rsa->e);
 380                 buffer_get_bignum(&e->input, k->rsa->d);
 381                 buffer_get_bignum(&e->input, k->rsa->iqmp);
 382
 383                 /* SSH and SSL have p and q swapped */
 384                 buffer_get_bignum(&e->input, k->rsa->q);        /* p */
 385                 buffer_get_bignum(&e->input, k->rsa->p);        /* q */
 386
 387                 /* Generate additional parameters */
 388                 rsa_generate_additional_parameters(k->rsa);
 389                 break;
 390         case 2:
 391                 type_name = buffer_get_string(&e->input, NULL);
 392                 type = key_type_from_name(type_name);
 393                 xfree(type_name);
 394                 switch(type) {
 395                 case KEY_DSA:
 396                         k = key_new_private(type);
 397                         buffer_get_bignum2(&e->input, k->dsa->p);
 398                         buffer_get_bignum2(&e->input, k->dsa->q);
 399                         buffer_get_bignum2(&e->input, k->dsa->g);
 400                         buffer_get_bignum2(&e->input, k->dsa->pub_key);
 401                         buffer_get_bignum2(&e->input, k->dsa->priv_key);
 402                         break;
 403                 case KEY_RSA:
 404                         k = key_new_private(type);
 405                         buffer_get_bignum2(&e->input, k->rsa->n);
 406                         buffer_get_bignum2(&e->input, k->rsa->e);
 407                         buffer_get_bignum2(&e->input, k->rsa->d);
 408                         buffer_get_bignum2(&e->input, k->rsa->iqmp);
 409                         buffer_get_bignum2(&e->input, k->rsa->p);
 410                         buffer_get_bignum2(&e->input, k->rsa->q);
 411
 412                         /* Generate additional parameters */
 413                         rsa_generate_additional_parameters(k->rsa);
 414                         break;
 415                 default:
 416                         buffer_clear(&e->input);
 417                         goto send;
 418                 }
 419                 break;
 420         }
 421         comment = buffer_get_string(&e->input, NULL);
 422         if (k == NULL) {
 423                 xfree(comment);
 424                 goto send;
 425         }
 426         success = 1;
 427         if (lookup_private_key(k, NULL, version) == NULL) {
 428                 if (tab->nentries == 0)
 429                         tab->identities = xmalloc(sizeof(Identity));
 430                 else
 431                         tab->identities = xrealloc(tab->identities,
 432                             (tab->nentries + 1) * sizeof(Identity));
 433                 tab->identities[tab->nentries].key = k;
 434                 tab->identities[tab->nentries].comment = comment;
 435                 /* Increment the number of identities. */
 436                 tab->nentries++;
 437         } else {
 438                 key_free(k);
 439                 xfree(comment);
 440         }
 441 send:
 442         buffer_put_int(&e->output, 1);
 443         buffer_put_char(&e->output,
 444             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 445 }
 446
 447
 448 #ifdef SMARTCARD
 449 static void
 450 process_add_smartcard_key (SocketEntry *e)
 451 {
 452         Idtab *tab;
 453         Key *n = NULL, *k = NULL;
 454         int success = 0;
 455         int sc_reader_num = 0;
 456
 457         sc_reader_num = buffer_get_int(&e->input);
 458
 459         k = sc_get_key(sc_reader_num);
 460         if (k == NULL) {
 461                 error("sc_get_pubkey failed");
 462                 goto send;
 463         }
 464         success = 1;
 465
 466         tab = idtab_lookup(1);
 467         k->type = KEY_RSA1;
 468         if (lookup_private_key(k, NULL, 1) == NULL) {
 469                 if (tab->nentries == 0)
 470                         tab->identities = xmalloc(sizeof(Identity));
 471                 else
 472                         tab->identities = xrealloc(tab->identities,
 473                             (tab->nentries + 1) * sizeof(Identity));
 474                 n = key_new(KEY_RSA1);
 475                 BN_copy(n->rsa->n, k->rsa->n);
 476                 BN_copy(n->rsa->e, k->rsa->e);
 477                 RSA_set_method(n->rsa, sc_get_engine());
 478                 tab->identities[tab->nentries].key = n;
 479                 tab->identities[tab->nentries].comment =
 480                     xstrdup("rsa1 smartcard");
 481                 tab->nentries++;
 482         }
 483         k->type = KEY_RSA;
 484         tab = idtab_lookup(2);
 485         if (lookup_private_key(k, NULL, 2) == NULL) {
 486                 if (tab->nentries == 0)
 487                         tab->identities = xmalloc(sizeof(Identity));
 488                 else
 489                         tab->identities = xrealloc(tab->identities,
 490                             (tab->nentries + 1) * sizeof(Identity));
 491                 n = key_new(KEY_RSA);
 492                 BN_copy(n->rsa->n, k->rsa->n);
 493                 BN_copy(n->rsa->e, k->rsa->e);
 494                 RSA_set_method(n->rsa, sc_get_engine());
 495                 tab->identities[tab->nentries].key = n;
 496                 tab->identities[tab->nentries].comment =
 497                     xstrdup("rsa smartcard");
 498                 tab->nentries++;
 499         }
 500         key_free(k);
 501 send:
 502         buffer_put_int(&e->output, 1);
 503         buffer_put_char(&e->output,
 504             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 505 }
 506
 507 static void
 508 process_remove_smartcard_key(SocketEntry *e)
 509 {
 510         Key *k = NULL, *private;
 511         int idx;
 512         int success = 0;
 513         int sc_reader_num = 0;
 514
 515         sc_reader_num = buffer_get_int(&e->input);
 516
 517         if ((k = sc_get_key(sc_reader_num)) == NULL) {
 518                 error("sc_get_pubkey failed");
 519         } else {
 520                 k->type = KEY_RSA1;
 521                 private = lookup_private_key(k, &idx, 1);
 522                 if (private != NULL) {
 523                         Idtab *tab = idtab_lookup(1);
 524                         key_free(tab->identities[idx].key);
 525                         xfree(tab->identities[idx].comment);
 526                         if (idx != tab->nentries)
 527                                 tab->identities[idx] = tab->identities[tab->nentries];
 528                         tab->nentries--;
 529                         success = 1;
 530                 }
 531                 k->type = KEY_RSA;
 532                 private = lookup_private_key(k, &idx, 2);
 533                 if (private != NULL) {
 534                         Idtab *tab = idtab_lookup(2);
 535                         key_free(tab->identities[idx].key);
 536                         xfree(tab->identities[idx].comment);
 537                         if (idx != tab->nentries)
 538                                 tab->identities[idx] = tab->identities[tab->nentries];
 539                         tab->nentries--;
 540                         success = 1;
 541                 }
 542                 key_free(k);
 543         }
 544
 545         buffer_put_int(&e->output, 1);
 546         buffer_put_char(&e->output,
 547             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 548 }
 549 #endif
 550
 551 /* dispatch incoming messages */
 552
 553 static void
 554 process_message(SocketEntry *e)
 555 {
 556         u_int msg_len;
 557         u_int type;
 558         u_char *cp;
 559         if (buffer_len(&e->input) < 5)
 560                 return;         /* Incomplete message. */
 561         cp = (u_char *) buffer_ptr(&e->input);
 562         msg_len = GET_32BIT(cp);
 563         if (msg_len > 256 * 1024) {
 564                 shutdown(e->fd, SHUT_RDWR);
 565                 close(e->fd);
 566                 e->type = AUTH_UNUSED;
 567                 return;
 568         }
 569         if (buffer_len(&e->input) < msg_len + 4)
 570                 return;
 571         buffer_consume(&e->input, 4);
 572         type = buffer_get_char(&e->input);
 573
 574         debug("type %d", type);
 575         switch (type) {
 576         /* ssh1 */
 577         case SSH_AGENTC_RSA_CHALLENGE:
 578                 process_authentication_challenge1(e);
 579                 break;
 580         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 581                 process_request_identities(e, 1);
 582                 break;
 583         case SSH_AGENTC_ADD_RSA_IDENTITY:
 584                 process_add_identity(e, 1);
 585                 break;
 586         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 587                 process_remove_identity(e, 1);
 588                 break;
 589         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 590                 process_remove_all_identities(e, 1);
 591                 break;
 592         /* ssh2 */
 593         case SSH2_AGENTC_SIGN_REQUEST:
 594                 process_sign_request2(e);
 595                 break;
 596         case SSH2_AGENTC_REQUEST_IDENTITIES:
 597                 process_request_identities(e, 2);
 598                 break;
 599         case SSH2_AGENTC_ADD_IDENTITY:
 600                 process_add_identity(e, 2);
 601                 break;
 602         case SSH2_AGENTC_REMOVE_IDENTITY:
 603                 process_remove_identity(e, 2);
 604                 break;
 605         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 606                 process_remove_all_identities(e, 2);
 607                 break;
 608 #ifdef SMARTCARD
 609         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 610                 process_add_smartcard_key(e);
 611                 break;
 612         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 613                 process_remove_smartcard_key(e);
 614                 break;
 615 #endif
 616         default:
 617                 /* Unknown message.  Respond with failure. */
 618                 error("Unknown message %d", type);
 619                 buffer_clear(&e->input);
 620                 buffer_put_int(&e->output, 1);
 621                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 622                 break;
 623         }
 624 }
 625
 626 static void
 627 new_socket(int type, int fd)
 628 {
 629         u_int i, old_alloc;
 630         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 631                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 632
 633         if (fd > max_fd)
 634                 max_fd = fd;
 635
 636         for (i = 0; i < sockets_alloc; i++)
 637                 if (sockets[i].type == AUTH_UNUSED) {
 638                         sockets[i].fd = fd;
 639                         sockets[i].type = type;
 640                         buffer_init(&sockets[i].input);
 641                         buffer_init(&sockets[i].output);
 642                         return;
 643                 }
 644         old_alloc = sockets_alloc;
 645         sockets_alloc += 10;
 646         if (sockets)
 647                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 648         else
 649                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 650         for (i = old_alloc; i < sockets_alloc; i++)
 651                 sockets[i].type = AUTH_UNUSED;
 652         sockets[old_alloc].type = type;
 653         sockets[old_alloc].fd = fd;
 654         buffer_init(&sockets[old_alloc].input);
 655         buffer_init(&sockets[old_alloc].output);
 656 }
 657
 658 static int
 659 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 660 {
 661         u_int i, sz;
 662         int n = 0;
 663
 664         for (i = 0; i < sockets_alloc; i++) {
 665                 switch (sockets[i].type) {
 666                 case AUTH_SOCKET:
 667                 case AUTH_CONNECTION:
 668                         n = MAX(n, sockets[i].fd);
 669                         break;
 670                 case AUTH_UNUSED:
 671                         break;
 672                 default:
 673                         fatal("Unknown socket type %d", sockets[i].type);
 674                         break;
 675                 }
 676         }
 677
 678         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 679         if (*fdrp == NULL || sz > *nallocp) {
 680                 if (*fdrp)
 681                         xfree(*fdrp);
 682                 if (*fdwp)
 683                         xfree(*fdwp);
 684                 *fdrp = xmalloc(sz);
 685                 *fdwp = xmalloc(sz);
 686                 *nallocp = sz;
 687         }
 688         if (n < *fdl)
 689                 debug("XXX shrink: %d < %d", n, *fdl);
 690         *fdl = n;
 691         memset(*fdrp, 0, sz);
 692         memset(*fdwp, 0, sz);
 693
 694         for (i = 0; i < sockets_alloc; i++) {
 695                 switch (sockets[i].type) {
 696                 case AUTH_SOCKET:
 697                 case AUTH_CONNECTION:
 698                         FD_SET(sockets[i].fd, *fdrp);
 699                         if (buffer_len(&sockets[i].output) > 0)
 700                                 FD_SET(sockets[i].fd, *fdwp);
 701                         break;
 702                 default:
 703                         break;
 704                 }
 705         }
 706         return (1);
 707 }
 708
 709 static void
 710 after_select(fd_set *readset, fd_set *writeset)
 711 {
 712         u_int i;
 713         int len, sock;
 714         socklen_t slen;
 715         char buf[1024];
 716         struct sockaddr_un sunaddr;
 717
 718         for (i = 0; i < sockets_alloc; i++)
 719                 switch (sockets[i].type) {
 720                 case AUTH_UNUSED:
 721                         break;
 722                 case AUTH_SOCKET:
 723                         if (FD_ISSET(sockets[i].fd, readset)) {
 724                                 slen = sizeof(sunaddr);
 725                                 sock = accept(sockets[i].fd,
 726                                     (struct sockaddr *) &sunaddr, &slen);
 727                                 if (sock < 0) {
 728                                         perror("accept from AUTH_SOCKET");
 729                                         break;
 730                                 }
 731                                 new_socket(AUTH_CONNECTION, sock);
 732                         }
 733                         break;
 734                 case AUTH_CONNECTION:
 735                         if (buffer_len(&sockets[i].output) > 0 &&
 736                             FD_ISSET(sockets[i].fd, writeset)) {
 737                                 do {
 738                                         len = write(sockets[i].fd,
 739                                             buffer_ptr(&sockets[i].output),
 740                                             buffer_len(&sockets[i].output));
 741                                         if (len == -1 && (errno == EAGAIN ||
 742                                             errno == EINTR))
 743                                                 continue;
 744                                         break;
 745                                 } while (1);
 746                                 if (len <= 0) {
 747                                         shutdown(sockets[i].fd, SHUT_RDWR);
 748                                         close(sockets[i].fd);
 749                                         sockets[i].type = AUTH_UNUSED;
 750                                         buffer_free(&sockets[i].input);
 751                                         buffer_free(&sockets[i].output);
 752                                         break;
 753                                 }
 754                                 buffer_consume(&sockets[i].output, len);
 755                         }
 756                         if (FD_ISSET(sockets[i].fd, readset)) {
 757                                 do {
 758                                         len = read(sockets[i].fd, buf, sizeof(buf));
 759                                         if (len == -1 && (errno == EAGAIN ||
 760                                             errno == EINTR))
 761                                                 continue;
 762                                         break;
 763                                 } while (1);
 764                                 if (len <= 0) {
 765                                         shutdown(sockets[i].fd, SHUT_RDWR);
 766                                         close(sockets[i].fd);
 767                                         sockets[i].type = AUTH_UNUSED;
 768                                         buffer_free(&sockets[i].input);
 769                                         buffer_free(&sockets[i].output);
 770                                         break;
 771                                 }
 772                                 buffer_append(&sockets[i].input, buf, len);
 773                                 process_message(&sockets[i]);
 774                         }
 775                         break;
 776                 default:
 777                         fatal("Unknown type %d", sockets[i].type);
 778                 }
 779 }
 780
 781 static void
 782 check_parent_exists(int sig)
 783 {
 784         int save_errno = errno;
 785
 786         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 787                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 788                 exit(1);
 789         }
 790         signal(SIGALRM, check_parent_exists);
 791         alarm(10);
 792         errno = save_errno;
 793 }
 794
 795 static void
 796 cleanup_socket(void)
 797 {
 798         if (socket_name[0])
 799                 unlink(socket_name);
 800         if (socket_dir[0])
 801                 rmdir(socket_dir);
 802 }
 803
 804 static void
 805 cleanup_exit(int i)
 806 {
 807         cleanup_socket();
 808         exit(i);
 809 }
 810
 811 static void
 812 cleanup_handler(int sig)
 813 {
 814         cleanup_socket();
 815         _exit(2);
 816 }
 817
 818 static void
 819 usage(void)
 820 {
 821         fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION);
 822         fprintf(stderr, "Usage: %s [-c | -s] [-k] [-d] [command [args...]]\n",
 823             __progname);
 824         exit(1);
 825 }
 826
 827 int
 828 main(int ac, char **av)
 829 {
 830         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 831         struct sockaddr_un sunaddr;
 832 #ifdef HAVE_SETRLIMIT
 833         struct rlimit rlim;
 834 #endif
 835 #ifdef HAVE_CYGWIN
 836         int prev_mask;
 837 #endif
 838         pid_t pid;
 839         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 840         extern int optind;
 841         fd_set *readsetp = NULL, *writesetp = NULL;
 842
 843         SSLeay_add_all_algorithms();
 844
 845         __progname = get_progname(av[0]);
 846         init_rng();
 847         seed_rng();
 848
 849 #ifdef __GNU_LIBRARY__
 850         while ((ch = getopt(ac, av, "+cdks")) != -1) {
 851 #else /* __GNU_LIBRARY__ */
 852         while ((ch = getopt(ac, av, "cdks")) != -1) {
 853 #endif /* __GNU_LIBRARY__ */
 854                 switch (ch) {
 855                 case 'c':
 856                         if (s_flag)
 857                                 usage();
 858                         c_flag++;
 859                         break;
 860                 case 'k':
 861                         k_flag++;
 862                         break;
 863                 case 's':
 864                         if (c_flag)
 865                                 usage();
 866                         s_flag++;
 867                         break;
 868                 case 'd':
 869                         if (d_flag)
 870                                 usage();
 871                         d_flag++;
 872                         break;
 873                 default:
 874                         usage();
 875                 }
 876         }
 877         ac -= optind;
 878         av += optind;
 879
 880         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
 881                 usage();
 882
 883         if (ac == 0 && !c_flag && !k_flag && !s_flag && !d_flag) {
 884                 shell = getenv("SHELL");
 885                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 886                         c_flag = 1;
 887         }
 888         if (k_flag) {
 889                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 890                 if (pidstr == NULL) {
 891                         fprintf(stderr, "%s not set, cannot kill agent\n",
 892                             SSH_AGENTPID_ENV_NAME);
 893                         exit(1);
 894                 }
 895                 pid = atoi(pidstr);
 896                 if (pid < 1) {
 897                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 898                             SSH_AGENTPID_ENV_NAME, pidstr);
 899                         exit(1);
 900                 }
 901                 if (kill(pid, SIGTERM) == -1) {
 902                         perror("kill");
 903                         exit(1);
 904                 }
 905                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 906                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 907                 printf(format, SSH_AGENTPID_ENV_NAME);
 908                 printf("echo Agent pid %d killed;\n", pid);
 909                 exit(0);
 910         }
 911         parent_pid = getpid();
 912
 913         /* Create private directory for agent socket */
 914         strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 915         if (mkdtemp(socket_dir) == NULL) {
 916                 perror("mkdtemp: private socket dir");
 917                 exit(1);
 918         }
 919         snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 920             parent_pid);
 921
 922         /*
 923          * Create socket early so it will exist before command gets run from
 924          * the parent.
 925          */
 926         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 927         if (sock < 0) {
 928                 perror("socket");
 929                 cleanup_exit(1);
 930         }
 931         memset(&sunaddr, 0, sizeof(sunaddr));
 932         sunaddr.sun_family = AF_UNIX;
 933         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 934 #ifdef HAVE_CYGWIN
 935         prev_mask = umask(0177);
 936 #endif
 937         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 938                 perror("bind");
 939 #ifdef HAVE_CYGWIN
 940                 umask(prev_mask);
 941 #endif
 942                 cleanup_exit(1);
 943         }
 944 #ifdef HAVE_CYGWIN
 945         umask(prev_mask);
 946 #endif
 947         if (listen(sock, 5) < 0) {
 948                 perror("listen");
 949                 cleanup_exit(1);
 950         }
 951
 952         /*
 953          * Fork, and have the parent execute the command, if any, or present
 954          * the socket data.  The child continues as the authentication agent.
 955          */
 956         if (d_flag) {
 957                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
 958                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 959                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 960                     SSH_AUTHSOCKET_ENV_NAME);
 961                 printf("echo Agent pid %d;\n", parent_pid);
 962                 goto skip;
 963         }
 964         pid = fork();
 965         if (pid == -1) {
 966                 perror("fork");
 967                 exit(1);
 968         }
 969         if (pid != 0) {         /* Parent - execute the given command. */
 970                 close(sock);
 971                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 972                 if (ac == 0) {
 973                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 974                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 975                             SSH_AUTHSOCKET_ENV_NAME);
 976                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 977                             SSH_AGENTPID_ENV_NAME);
 978                         printf("echo Agent pid %d;\n", pid);
 979                         exit(0);
 980                 }
 981                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 982                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 983                         perror("setenv");
 984                         exit(1);
 985                 }
 986                 execvp(av[0], av);
 987                 perror(av[0]);
 988                 exit(1);
 989         }
 990         close(0);
 991         close(1);
 992         close(2);
 993
 994 #ifdef HAVE_SETRLIMIT
 995         /* deny core dumps, since memory contains unencrypted private keys */
 996         rlim.rlim_cur = rlim.rlim_max = 0;
 997         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
 998                 perror("setrlimit rlimit_core failed");
 999                 cleanup_exit(1);
1000         }
1001 #endif
1002         if (setsid() == -1) {
1003                 perror("setsid");
1004                 cleanup_exit(1);
1005         }
1006
1007 skip:
1008         if (atexit(cleanup_socket) < 0) {
1009                 perror("atexit");
1010                 cleanup_exit(1);
1011         }
1012         new_socket(AUTH_SOCKET, sock);
1013         if (ac > 0) {
1014                 signal(SIGALRM, check_parent_exists);
1015                 alarm(10);
1016         }
1017         idtab_init();
1018         if (!d_flag)
1019                 signal(SIGINT, SIG_IGN);
1020         signal(SIGPIPE, SIG_IGN);
1021         signal(SIGHUP, cleanup_handler);
1022         signal(SIGTERM, cleanup_handler);
1023         nalloc = 0;
1024
1025         while (1) {
1026                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1027                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1028                         if (errno == EINTR)
1029                                 continue;
1030                         exit(1);
1031                 }
1032                 after_select(readsetp, writesetp);
1033         }
1034         /* NOTREACHED */
1035 }