ssh-agent.c

   1 /*      $OpenBSD: ssh-agent.c,v 1.76 2001/12/27 18:22:16 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 1.76 2001/12/27 18:22:16 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 enum {
  65         AUTH_UNUSED,
  66         AUTH_SOCKET,
  67         AUTH_CONNECTION
  68 } sock_type;
  69
  70 typedef struct {
  71         int fd;
  72         sock_type type;
  73         Buffer input;
  74         Buffer output;
  75 } SocketEntry;
  76
  77 u_int sockets_alloc = 0;
  78 SocketEntry *sockets = NULL;
  79
  80 typedef struct {
  81         Key *key;
  82         char *comment;
  83 } Identity;
  84
  85 typedef struct {
  86         int nentries;
  87         Identity *identities;
  88 } Idtab;
  89
  90 /* private key table, one per protocol version */
  91 Idtab idtable[3];
  92
  93 int max_fd = 0;
  94
  95 /* pid of shell == parent of agent */
  96 pid_t parent_pid = -1;
  97
  98 /* pathname and directory for AUTH_SOCKET */
  99 char socket_name[1024];
 100 char socket_dir[1024];
 101
 102 #ifdef HAVE___PROGNAME
 103 extern char *__progname;
 104 #else
 105 char *__progname;
 106 #endif
 107
 108 static void
 109 idtab_init(void)
 110 {
 111         int i;
 112         for (i = 0; i <=2; i++) {
 113                 idtable[i].identities = NULL;
 114                 idtable[i].nentries = 0;
 115         }
 116 }
 117
 118 /* return private key table for requested protocol version */
 119 static Idtab *
 120 idtab_lookup(int version)
 121 {
 122         if (version < 1 || version > 2)
 123                 fatal("internal error, bad protocol version %d", version);
 124         return &idtable[version];
 125 }
 126
 127 /* return matching private key for given public key */
 128 static Key *
 129 lookup_private_key(Key *key, int *idx, int version)
 130 {
 131         int i;
 132         Idtab *tab = idtab_lookup(version);
 133         for (i = 0; i < tab->nentries; i++) {
 134                 if (key_equal(key, tab->identities[i].key)) {
 135                         if (idx != NULL)
 136                                 *idx = i;
 137                         return tab->identities[i].key;
 138                 }
 139         }
 140         return NULL;
 141 }
 142
 143 /* send list of supported public keys to 'client' */
 144 static void
 145 process_request_identities(SocketEntry *e, int version)
 146 {
 147         Idtab *tab = idtab_lookup(version);
 148         Buffer msg;
 149         int i;
 150
 151         buffer_init(&msg);
 152         buffer_put_char(&msg, (version == 1) ?
 153             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 154         buffer_put_int(&msg, tab->nentries);
 155         for (i = 0; i < tab->nentries; i++) {
 156                 Identity *id = &tab->identities[i];
 157                 if (id->key->type == KEY_RSA1) {
 158                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 159                         buffer_put_bignum(&msg, id->key->rsa->e);
 160                         buffer_put_bignum(&msg, id->key->rsa->n);
 161                 } else {
 162                         u_char *blob;
 163                         u_int blen;
 164                         key_to_blob(id->key, &blob, &blen);
 165                         buffer_put_string(&msg, blob, blen);
 166                         xfree(blob);
 167                 }
 168                 buffer_put_cstring(&msg, id->comment);
 169         }
 170         buffer_put_int(&e->output, buffer_len(&msg));
 171         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 172         buffer_free(&msg);
 173 }
 174
 175 /* ssh1 only */
 176 static void
 177 process_authentication_challenge1(SocketEntry *e)
 178 {
 179         Key *key, *private;
 180         BIGNUM *challenge;
 181         int i, len;
 182         Buffer msg;
 183         MD5_CTX md;
 184         u_char buf[32], mdbuf[16], session_id[16];
 185         u_int response_type;
 186
 187         buffer_init(&msg);
 188         key = key_new(KEY_RSA1);
 189         if ((challenge = BN_new()) == NULL)
 190                 fatal("process_authentication_challenge1: BN_new failed");
 191
 192         buffer_get_int(&e->input);                              /* ignored */
 193         buffer_get_bignum(&e->input, key->rsa->e);
 194         buffer_get_bignum(&e->input, key->rsa->n);
 195         buffer_get_bignum(&e->input, challenge);
 196
 197         /* Only protocol 1.1 is supported */
 198         if (buffer_len(&e->input) == 0)
 199                 goto failure;
 200         buffer_get(&e->input, (char *) session_id, 16);
 201         response_type = buffer_get_int(&e->input);
 202         if (response_type != 1)
 203                 goto failure;
 204
 205         private = lookup_private_key(key, NULL, 1);
 206         if (private != NULL) {
 207                 /* Decrypt the challenge using the private key. */
 208                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 209                         goto failure;
 210
 211                 /* The response is MD5 of decrypted challenge plus session id. */
 212                 len = BN_num_bytes(challenge);
 213                 if (len <= 0 || len > 32) {
 214                         log("process_authentication_challenge: bad challenge length %d", len);
 215                         goto failure;
 216                 }
 217                 memset(buf, 0, 32);
 218                 BN_bn2bin(challenge, buf + 32 - len);
 219                 MD5_Init(&md);
 220                 MD5_Update(&md, buf, 32);
 221                 MD5_Update(&md, session_id, 16);
 222                 MD5_Final(mdbuf, &md);
 223
 224                 /* Send the response. */
 225                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 226                 for (i = 0; i < 16; i++)
 227                         buffer_put_char(&msg, mdbuf[i]);
 228                 goto send;
 229         }
 230
 231 failure:
 232         /* Unknown identity or protocol error.  Send failure. */
 233         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 234 send:
 235         buffer_put_int(&e->output, buffer_len(&msg));
 236         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 237         key_free(key);
 238         BN_clear_free(challenge);
 239         buffer_free(&msg);
 240 }
 241
 242 /* ssh2 only */
 243 static void
 244 process_sign_request2(SocketEntry *e)
 245 {
 246         extern int datafellows;
 247         Key *key, *private;
 248         u_char *blob, *data, *signature = NULL;
 249         u_int blen, dlen, slen = 0;
 250         int flags;
 251         Buffer msg;
 252         int ok = -1;
 253
 254         datafellows = 0;
 255
 256         blob = buffer_get_string(&e->input, &blen);
 257         data = buffer_get_string(&e->input, &dlen);
 258
 259         flags = buffer_get_int(&e->input);
 260         if (flags & SSH_AGENT_OLD_SIGNATURE)
 261                 datafellows = SSH_BUG_SIGBLOB;
 262
 263         key = key_from_blob(blob, blen);
 264         if (key != NULL) {
 265                 private = lookup_private_key(key, NULL, 2);
 266                 if (private != NULL)
 267                         ok = key_sign(private, &signature, &slen, data, dlen);
 268         }
 269         key_free(key);
 270         buffer_init(&msg);
 271         if (ok == 0) {
 272                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 273                 buffer_put_string(&msg, signature, slen);
 274         } else {
 275                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 276         }
 277         buffer_put_int(&e->output, buffer_len(&msg));
 278         buffer_append(&e->output, buffer_ptr(&msg),
 279             buffer_len(&msg));
 280         buffer_free(&msg);
 281         xfree(data);
 282         xfree(blob);
 283         if (signature != NULL)
 284                 xfree(signature);
 285 }
 286
 287 /* shared */
 288 static void
 289 process_remove_identity(SocketEntry *e, int version)
 290 {
 291         Key *key = NULL, *private;
 292         u_char *blob;
 293         u_int blen;
 294         u_int bits;
 295         int success = 0;
 296
 297         switch (version) {
 298         case 1:
 299                 key = key_new(KEY_RSA1);
 300                 bits = buffer_get_int(&e->input);
 301                 buffer_get_bignum(&e->input, key->rsa->e);
 302                 buffer_get_bignum(&e->input, key->rsa->n);
 303
 304                 if (bits != key_size(key))
 305                         log("Warning: identity keysize mismatch: actual %d, announced %d",
 306                             key_size(key), bits);
 307                 break;
 308         case 2:
 309                 blob = buffer_get_string(&e->input, &blen);
 310                 key = key_from_blob(blob, blen);
 311                 xfree(blob);
 312                 break;
 313         }
 314         if (key != NULL) {
 315                 int idx;
 316                 private = lookup_private_key(key, &idx, version);
 317                 if (private != NULL) {
 318                         /*
 319                          * We have this key.  Free the old key.  Since we
 320                          * don\'t want to leave empty slots in the middle of
 321                          * the array, we actually free the key there and move
 322                          * all the entries between the empty slot and the end
 323                          * of the array.
 324                          */
 325                         Idtab *tab = idtab_lookup(version);
 326                         key_free(tab->identities[idx].key);
 327                         xfree(tab->identities[idx].comment);
 328                         if (tab->nentries < 1)
 329                                 fatal("process_remove_identity: "
 330                                     "internal error: tab->nentries %d",
 331                                     tab->nentries);
 332                         if (idx != tab->nentries - 1) {
 333                                 int i;
 334                                 for (i = idx; i < tab->nentries - 1; i++)
 335                                         tab->identities[i] = tab->identities[i+1];
 336                         }
 337                         tab->identities[tab->nentries - 1].key = NULL;
 338                         tab->identities[tab->nentries - 1].comment = NULL;
 339                         tab->nentries--;
 340                         success = 1;
 341                 }
 342                 key_free(key);
 343         }
 344         buffer_put_int(&e->output, 1);
 345         buffer_put_char(&e->output,
 346             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 347 }
 348
 349 static void
 350 process_remove_all_identities(SocketEntry *e, int version)
 351 {
 352         u_int i;
 353         Idtab *tab = idtab_lookup(version);
 354
 355         /* Loop over all identities and clear the keys. */
 356         for (i = 0; i < tab->nentries; i++) {
 357                 key_free(tab->identities[i].key);
 358                 xfree(tab->identities[i].comment);
 359         }
 360
 361         /* Mark that there are no identities. */
 362         tab->nentries = 0;
 363
 364         /* Send success. */
 365         buffer_put_int(&e->output, 1);
 366         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 367         return;
 368 }
 369
 370 static void
 371 process_add_identity(SocketEntry *e, int version)
 372 {
 373         Key *k = NULL;
 374         char *type_name;
 375         char *comment;
 376         int type, success = 0;
 377         Idtab *tab = idtab_lookup(version);
 378
 379         switch (version) {
 380         case 1:
 381                 k = key_new_private(KEY_RSA1);
 382                 buffer_get_int(&e->input);                      /* ignored */
 383                 buffer_get_bignum(&e->input, k->rsa->n);
 384                 buffer_get_bignum(&e->input, k->rsa->e);
 385                 buffer_get_bignum(&e->input, k->rsa->d);
 386                 buffer_get_bignum(&e->input, k->rsa->iqmp);
 387
 388                 /* SSH and SSL have p and q swapped */
 389                 buffer_get_bignum(&e->input, k->rsa->q);        /* p */
 390                 buffer_get_bignum(&e->input, k->rsa->p);        /* q */
 391
 392                 /* Generate additional parameters */
 393                 rsa_generate_additional_parameters(k->rsa);
 394                 break;
 395         case 2:
 396                 type_name = buffer_get_string(&e->input, NULL);
 397                 type = key_type_from_name(type_name);
 398                 xfree(type_name);
 399                 switch (type) {
 400                 case KEY_DSA:
 401                         k = key_new_private(type);
 402                         buffer_get_bignum2(&e->input, k->dsa->p);
 403                         buffer_get_bignum2(&e->input, k->dsa->q);
 404                         buffer_get_bignum2(&e->input, k->dsa->g);
 405                         buffer_get_bignum2(&e->input, k->dsa->pub_key);
 406                         buffer_get_bignum2(&e->input, k->dsa->priv_key);
 407                         break;
 408                 case KEY_RSA:
 409                         k = key_new_private(type);
 410                         buffer_get_bignum2(&e->input, k->rsa->n);
 411                         buffer_get_bignum2(&e->input, k->rsa->e);
 412                         buffer_get_bignum2(&e->input, k->rsa->d);
 413                         buffer_get_bignum2(&e->input, k->rsa->iqmp);
 414                         buffer_get_bignum2(&e->input, k->rsa->p);
 415                         buffer_get_bignum2(&e->input, k->rsa->q);
 416
 417                         /* Generate additional parameters */
 418                         rsa_generate_additional_parameters(k->rsa);
 419                         break;
 420                 default:
 421                         buffer_clear(&e->input);
 422                         goto send;
 423                 }
 424                 break;
 425         }
 426         comment = buffer_get_string(&e->input, NULL);
 427         if (k == NULL) {
 428                 xfree(comment);
 429                 goto send;
 430         }
 431         success = 1;
 432         if (lookup_private_key(k, NULL, version) == NULL) {
 433                 if (tab->nentries == 0)
 434                         tab->identities = xmalloc(sizeof(Identity));
 435                 else
 436                         tab->identities = xrealloc(tab->identities,
 437                             (tab->nentries + 1) * sizeof(Identity));
 438                 tab->identities[tab->nentries].key = k;
 439                 tab->identities[tab->nentries].comment = comment;
 440                 /* Increment the number of identities. */
 441                 tab->nentries++;
 442         } else {
 443                 key_free(k);
 444                 xfree(comment);
 445         }
 446 send:
 447         buffer_put_int(&e->output, 1);
 448         buffer_put_char(&e->output,
 449             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 450 }
 451
 452
 453 #ifdef SMARTCARD
 454 static void
 455 process_add_smartcard_key (SocketEntry *e)
 456 {
 457         Idtab *tab;
 458         Key *n = NULL, *k = NULL;
 459         char *sc_reader_id = NULL;
 460         int success = 0;
 461
 462         sc_reader_id = buffer_get_string(&e->input, NULL);
 463         k = sc_get_key(sc_reader_id);
 464         xfree(sc_reader_id);
 465
 466         if (k == NULL) {
 467                 error("sc_get_pubkey failed");
 468                 goto send;
 469         }
 470         success = 1;
 471
 472         tab = idtab_lookup(1);
 473         k->type = KEY_RSA1;
 474         if (lookup_private_key(k, NULL, 1) == NULL) {
 475                 if (tab->nentries == 0)
 476                         tab->identities = xmalloc(sizeof(Identity));
 477                 else
 478                         tab->identities = xrealloc(tab->identities,
 479                             (tab->nentries + 1) * sizeof(Identity));
 480                 n = key_new(KEY_RSA1);
 481                 BN_copy(n->rsa->n, k->rsa->n);
 482                 BN_copy(n->rsa->e, k->rsa->e);
 483                 RSA_set_method(n->rsa, sc_get_engine());
 484                 tab->identities[tab->nentries].key = n;
 485                 tab->identities[tab->nentries].comment =
 486                     xstrdup("rsa1 smartcard");
 487                 tab->nentries++;
 488         }
 489         k->type = KEY_RSA;
 490         tab = idtab_lookup(2);
 491         if (lookup_private_key(k, NULL, 2) == NULL) {
 492                 if (tab->nentries == 0)
 493                         tab->identities = xmalloc(sizeof(Identity));
 494                 else
 495                         tab->identities = xrealloc(tab->identities,
 496                             (tab->nentries + 1) * sizeof(Identity));
 497                 n = key_new(KEY_RSA);
 498                 BN_copy(n->rsa->n, k->rsa->n);
 499                 BN_copy(n->rsa->e, k->rsa->e);
 500                 RSA_set_method(n->rsa, sc_get_engine());
 501                 tab->identities[tab->nentries].key = n;
 502                 tab->identities[tab->nentries].comment =
 503                     xstrdup("rsa smartcard");
 504                 tab->nentries++;
 505         }
 506         key_free(k);
 507 send:
 508         buffer_put_int(&e->output, 1);
 509         buffer_put_char(&e->output,
 510             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 511 }
 512
 513 static void
 514 process_remove_smartcard_key(SocketEntry *e)
 515 {
 516         Key *k = NULL, *private;
 517         int idx;
 518         int success = 0;
 519         char *sc_reader_id = NULL;
 520
 521         sc_reader_id = buffer_get_string(&e->input, NULL);
 522         k = sc_get_key(sc_reader_id);
 523         xfree(sc_reader_id);
 524
 525         if (k == NULL) {
 526                 error("sc_get_pubkey failed");
 527         } else {
 528                 k->type = KEY_RSA1;
 529                 private = lookup_private_key(k, &idx, 1);
 530                 if (private != NULL) {
 531                         Idtab *tab = idtab_lookup(1);
 532                         key_free(tab->identities[idx].key);
 533                         xfree(tab->identities[idx].comment);
 534                         if (idx != tab->nentries)
 535                                 tab->identities[idx] = tab->identities[tab->nentries];
 536                         tab->nentries--;
 537                         success = 1;
 538                 }
 539                 k->type = KEY_RSA;
 540                 private = lookup_private_key(k, &idx, 2);
 541                 if (private != NULL) {
 542                         Idtab *tab = idtab_lookup(2);
 543                         key_free(tab->identities[idx].key);
 544                         xfree(tab->identities[idx].comment);
 545                         if (idx != tab->nentries)
 546                                 tab->identities[idx] = tab->identities[tab->nentries];
 547                         tab->nentries--;
 548                         success = 1;
 549                 }
 550                 key_free(k);
 551         }
 552
 553         buffer_put_int(&e->output, 1);
 554         buffer_put_char(&e->output,
 555             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 556 }
 557 #endif /* SMARTCARD */
 558
 559 /* dispatch incoming messages */
 560
 561 static void
 562 process_message(SocketEntry *e)
 563 {
 564         u_int msg_len;
 565         u_int type;
 566         u_char *cp;
 567         if (buffer_len(&e->input) < 5)
 568                 return;         /* Incomplete message. */
 569         cp = (u_char *) buffer_ptr(&e->input);
 570         msg_len = GET_32BIT(cp);
 571         if (msg_len > 256 * 1024) {
 572                 shutdown(e->fd, SHUT_RDWR);
 573                 close(e->fd);
 574                 e->type = AUTH_UNUSED;
 575                 return;
 576         }
 577         if (buffer_len(&e->input) < msg_len + 4)
 578                 return;
 579         buffer_consume(&e->input, 4);
 580         type = buffer_get_char(&e->input);
 581
 582         debug("type %d", type);
 583         switch (type) {
 584         /* ssh1 */
 585         case SSH_AGENTC_RSA_CHALLENGE:
 586                 process_authentication_challenge1(e);
 587                 break;
 588         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 589                 process_request_identities(e, 1);
 590                 break;
 591         case SSH_AGENTC_ADD_RSA_IDENTITY:
 592                 process_add_identity(e, 1);
 593                 break;
 594         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 595                 process_remove_identity(e, 1);
 596                 break;
 597         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 598                 process_remove_all_identities(e, 1);
 599                 break;
 600         /* ssh2 */
 601         case SSH2_AGENTC_SIGN_REQUEST:
 602                 process_sign_request2(e);
 603                 break;
 604         case SSH2_AGENTC_REQUEST_IDENTITIES:
 605                 process_request_identities(e, 2);
 606                 break;
 607         case SSH2_AGENTC_ADD_IDENTITY:
 608                 process_add_identity(e, 2);
 609                 break;
 610         case SSH2_AGENTC_REMOVE_IDENTITY:
 611                 process_remove_identity(e, 2);
 612                 break;
 613         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 614                 process_remove_all_identities(e, 2);
 615                 break;
 616 #ifdef SMARTCARD
 617         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 618                 process_add_smartcard_key(e);
 619                 break;
 620         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 621                 process_remove_smartcard_key(e);
 622                 break;
 623 #endif /* SMARTCARD */
 624         default:
 625                 /* Unknown message.  Respond with failure. */
 626                 error("Unknown message %d", type);
 627                 buffer_clear(&e->input);
 628                 buffer_put_int(&e->output, 1);
 629                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 630                 break;
 631         }
 632 }
 633
 634 static void
 635 new_socket(sock_type type, int fd)
 636 {
 637         u_int i, old_alloc;
 638         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 639                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 640
 641         if (fd > max_fd)
 642                 max_fd = fd;
 643
 644         for (i = 0; i < sockets_alloc; i++)
 645                 if (sockets[i].type == AUTH_UNUSED) {
 646                         sockets[i].fd = fd;
 647                         sockets[i].type = type;
 648                         buffer_init(&sockets[i].input);
 649                         buffer_init(&sockets[i].output);
 650                         return;
 651                 }
 652         old_alloc = sockets_alloc;
 653         sockets_alloc += 10;
 654         if (sockets)
 655                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 656         else
 657                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 658         for (i = old_alloc; i < sockets_alloc; i++)
 659                 sockets[i].type = AUTH_UNUSED;
 660         sockets[old_alloc].type = type;
 661         sockets[old_alloc].fd = fd;
 662         buffer_init(&sockets[old_alloc].input);
 663         buffer_init(&sockets[old_alloc].output);
 664 }
 665
 666 static int
 667 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 668 {
 669         u_int i, sz;
 670         int n = 0;
 671
 672         for (i = 0; i < sockets_alloc; i++) {
 673                 switch (sockets[i].type) {
 674                 case AUTH_SOCKET:
 675                 case AUTH_CONNECTION:
 676                         n = MAX(n, sockets[i].fd);
 677                         break;
 678                 case AUTH_UNUSED:
 679                         break;
 680                 default:
 681                         fatal("Unknown socket type %d", sockets[i].type);
 682                         break;
 683                 }
 684         }
 685
 686         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 687         if (*fdrp == NULL || sz > *nallocp) {
 688                 if (*fdrp)
 689                         xfree(*fdrp);
 690                 if (*fdwp)
 691                         xfree(*fdwp);
 692                 *fdrp = xmalloc(sz);
 693                 *fdwp = xmalloc(sz);
 694                 *nallocp = sz;
 695         }
 696         if (n < *fdl)
 697                 debug("XXX shrink: %d < %d", n, *fdl);
 698         *fdl = n;
 699         memset(*fdrp, 0, sz);
 700         memset(*fdwp, 0, sz);
 701
 702         for (i = 0; i < sockets_alloc; i++) {
 703                 switch (sockets[i].type) {
 704                 case AUTH_SOCKET:
 705                 case AUTH_CONNECTION:
 706                         FD_SET(sockets[i].fd, *fdrp);
 707                         if (buffer_len(&sockets[i].output) > 0)
 708                                 FD_SET(sockets[i].fd, *fdwp);
 709                         break;
 710                 default:
 711                         break;
 712                 }
 713         }
 714         return (1);
 715 }
 716
 717 static void
 718 after_select(fd_set *readset, fd_set *writeset)
 719 {
 720         u_int i;
 721         int len, sock;
 722         socklen_t slen;
 723         char buf[1024];
 724         struct sockaddr_un sunaddr;
 725
 726         for (i = 0; i < sockets_alloc; i++)
 727                 switch (sockets[i].type) {
 728                 case AUTH_UNUSED:
 729                         break;
 730                 case AUTH_SOCKET:
 731                         if (FD_ISSET(sockets[i].fd, readset)) {
 732                                 slen = sizeof(sunaddr);
 733                                 sock = accept(sockets[i].fd,
 734                                     (struct sockaddr *) &sunaddr, &slen);
 735                                 if (sock < 0) {
 736                                         perror("accept from AUTH_SOCKET");
 737                                         break;
 738                                 }
 739                                 new_socket(AUTH_CONNECTION, sock);
 740                         }
 741                         break;
 742                 case AUTH_CONNECTION:
 743                         if (buffer_len(&sockets[i].output) > 0 &&
 744                             FD_ISSET(sockets[i].fd, writeset)) {
 745                                 do {
 746                                         len = write(sockets[i].fd,
 747                                             buffer_ptr(&sockets[i].output),
 748                                             buffer_len(&sockets[i].output));
 749                                         if (len == -1 && (errno == EAGAIN ||
 750                                             errno == EINTR))
 751                                                 continue;
 752                                         break;
 753                                 } while (1);
 754                                 if (len <= 0) {
 755                                         shutdown(sockets[i].fd, SHUT_RDWR);
 756                                         close(sockets[i].fd);
 757                                         sockets[i].type = AUTH_UNUSED;
 758                                         buffer_free(&sockets[i].input);
 759                                         buffer_free(&sockets[i].output);
 760                                         break;
 761                                 }
 762                                 buffer_consume(&sockets[i].output, len);
 763                         }
 764                         if (FD_ISSET(sockets[i].fd, readset)) {
 765                                 do {
 766                                         len = read(sockets[i].fd, buf, sizeof(buf));
 767                                         if (len == -1 && (errno == EAGAIN ||
 768                                             errno == EINTR))
 769                                                 continue;
 770                                         break;
 771                                 } while (1);
 772                                 if (len <= 0) {
 773                                         shutdown(sockets[i].fd, SHUT_RDWR);
 774                                         close(sockets[i].fd);
 775                                         sockets[i].type = AUTH_UNUSED;
 776                                         buffer_free(&sockets[i].input);
 777                                         buffer_free(&sockets[i].output);
 778                                         break;
 779                                 }
 780                                 buffer_append(&sockets[i].input, buf, len);
 781                                 process_message(&sockets[i]);
 782                         }
 783                         break;
 784                 default:
 785                         fatal("Unknown type %d", sockets[i].type);
 786                 }
 787 }
 788
 789 static void
 790 cleanup_socket(void)
 791 {
 792         if (socket_name[0])
 793                 unlink(socket_name);
 794         if (socket_dir[0])
 795                 rmdir(socket_dir);
 796 }
 797
 798 static void
 799 cleanup_exit(int i)
 800 {
 801         cleanup_socket();
 802         exit(i);
 803 }
 804
 805 static void
 806 cleanup_handler(int sig)
 807 {
 808         cleanup_socket();
 809         _exit(2);
 810 }
 811
 812 static void
 813 check_parent_exists(int sig)
 814 {
 815         int save_errno = errno;
 816
 817         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 818                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 819                 cleanup_handler(sig); /* safe */
 820         }
 821         signal(SIGALRM, check_parent_exists);
 822         alarm(10);
 823         errno = save_errno;
 824 }
 825
 826 static void
 827 usage(void)
 828 {
 829         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 830             __progname);
 831         fprintf(stderr, "Options:\n");
 832         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 833         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 834         fprintf(stderr, "  -k          Kill the current agent.\n");
 835         fprintf(stderr, "  -d          Debug mode.\n");
 836         exit(1);
 837 }
 838
 839 int
 840 main(int ac, char **av)
 841 {
 842         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 843         struct sockaddr_un sunaddr;
 844 #ifdef HAVE_SETRLIMIT
 845         struct rlimit rlim;
 846 #endif
 847 #ifdef HAVE_CYGWIN
 848         int prev_mask;
 849 #endif
 850         pid_t pid;
 851         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 852         extern int optind;
 853         fd_set *readsetp = NULL, *writesetp = NULL;
 854
 855         SSLeay_add_all_algorithms();
 856
 857         __progname = get_progname(av[0]);
 858         init_rng();
 859         seed_rng();
 860
 861 #ifdef __GNU_LIBRARY__
 862         while ((ch = getopt(ac, av, "+cdks")) != -1) {
 863 #else /* __GNU_LIBRARY__ */
 864         while ((ch = getopt(ac, av, "cdks")) != -1) {
 865 #endif /* __GNU_LIBRARY__ */
 866                 switch (ch) {
 867                 case 'c':
 868                         if (s_flag)
 869                                 usage();
 870                         c_flag++;
 871                         break;
 872                 case 'k':
 873                         k_flag++;
 874                         break;
 875                 case 's':
 876                         if (c_flag)
 877                                 usage();
 878                         s_flag++;
 879                         break;
 880                 case 'd':
 881                         if (d_flag)
 882                                 usage();
 883                         d_flag++;
 884                         break;
 885                 default:
 886                         usage();
 887                 }
 888         }
 889         ac -= optind;
 890         av += optind;
 891
 892         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
 893                 usage();
 894
 895         if (ac == 0 && !c_flag && !k_flag && !s_flag && !d_flag) {
 896                 shell = getenv("SHELL");
 897                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 898                         c_flag = 1;
 899         }
 900         if (k_flag) {
 901                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 902                 if (pidstr == NULL) {
 903                         fprintf(stderr, "%s not set, cannot kill agent\n",
 904                             SSH_AGENTPID_ENV_NAME);
 905                         exit(1);
 906                 }
 907                 pid = atoi(pidstr);
 908                 if (pid < 1) {
 909                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 910                             SSH_AGENTPID_ENV_NAME, pidstr);
 911                         exit(1);
 912                 }
 913                 if (kill(pid, SIGTERM) == -1) {
 914                         perror("kill");
 915                         exit(1);
 916                 }
 917                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 918                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 919                 printf(format, SSH_AGENTPID_ENV_NAME);
 920                 printf("echo Agent pid %d killed;\n", pid);
 921                 exit(0);
 922         }
 923         parent_pid = getpid();
 924
 925         /* Create private directory for agent socket */
 926         strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 927         if (mkdtemp(socket_dir) == NULL) {
 928                 perror("mkdtemp: private socket dir");
 929                 exit(1);
 930         }
 931         snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 932             parent_pid);
 933
 934         /*
 935          * Create socket early so it will exist before command gets run from
 936          * the parent.
 937          */
 938         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 939         if (sock < 0) {
 940                 perror("socket");
 941                 cleanup_exit(1);
 942         }
 943         memset(&sunaddr, 0, sizeof(sunaddr));
 944         sunaddr.sun_family = AF_UNIX;
 945         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 946 #ifdef HAVE_CYGWIN
 947         prev_mask = umask(0177);
 948 #endif
 949         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 950                 perror("bind");
 951 #ifdef HAVE_CYGWIN
 952                 umask(prev_mask);
 953 #endif
 954                 cleanup_exit(1);
 955         }
 956 #ifdef HAVE_CYGWIN
 957         umask(prev_mask);
 958 #endif
 959         if (listen(sock, 5) < 0) {
 960                 perror("listen");
 961                 cleanup_exit(1);
 962         }
 963
 964         /*
 965          * Fork, and have the parent execute the command, if any, or present
 966          * the socket data.  The child continues as the authentication agent.
 967          */
 968         if (d_flag) {
 969                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
 970                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 971                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 972                     SSH_AUTHSOCKET_ENV_NAME);
 973                 printf("echo Agent pid %d;\n", parent_pid);
 974                 goto skip;
 975         }
 976         pid = fork();
 977         if (pid == -1) {
 978                 perror("fork");
 979                 exit(1);
 980         }
 981         if (pid != 0) {         /* Parent - execute the given command. */
 982                 close(sock);
 983                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 984                 if (ac == 0) {
 985                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 986                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 987                             SSH_AUTHSOCKET_ENV_NAME);
 988                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 989                             SSH_AGENTPID_ENV_NAME);
 990                         printf("echo Agent pid %d;\n", pid);
 991                         exit(0);
 992                 }
 993                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 994                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 995                         perror("setenv");
 996                         exit(1);
 997                 }
 998                 execvp(av[0], av);
 999                 perror(av[0]);
1000                 exit(1);
1001         }
1002
1003         if (setsid() == -1) {
1004                 perror("setsid");
1005                 cleanup_exit(1);
1006         }
1007
1008         (void)chdir("/");
1009         close(0);
1010         close(1);
1011         close(2);
1012
1013 #ifdef HAVE_SETRLIMIT
1014         /* deny core dumps, since memory contains unencrypted private keys */
1015         rlim.rlim_cur = rlim.rlim_max = 0;
1016         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1017                 perror("setrlimit rlimit_core failed");
1018                 cleanup_exit(1);
1019         }
1020 #endif
1021
1022 skip:
1023         if (atexit(cleanup_socket) < 0) {
1024                 perror("atexit");
1025                 cleanup_exit(1);
1026         }
1027         new_socket(AUTH_SOCKET, sock);
1028         if (ac > 0) {
1029                 signal(SIGALRM, check_parent_exists);
1030                 alarm(10);
1031         }
1032         idtab_init();
1033         if (!d_flag)
1034                 signal(SIGINT, SIG_IGN);
1035         signal(SIGPIPE, SIG_IGN);
1036         signal(SIGHUP, cleanup_handler);
1037         signal(SIGTERM, cleanup_handler);
1038         nalloc = 0;
1039
1040         while (1) {
1041                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1042                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1043                         if (errno == EINTR)
1044                                 continue;
1045                         exit(1);
1046                 }
1047                 after_select(readsetp, writesetp);
1048         }
1049         /* NOTREACHED */
1050 }