ssh-agent.c

   1 /*      $OpenBSD: ssh-agent.c,v 1.75 2001/12/19 07:18:56 deraadt 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 1.75 2001/12/19 07:18:56 deraadt 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         challenge = BN_new();
 190
 191         buffer_get_int(&e->input);                              /* ignored */
 192         buffer_get_bignum(&e->input, key->rsa->e);
 193         buffer_get_bignum(&e->input, key->rsa->n);
 194         buffer_get_bignum(&e->input, challenge);
 195
 196         /* Only protocol 1.1 is supported */
 197         if (buffer_len(&e->input) == 0)
 198                 goto failure;
 199         buffer_get(&e->input, (char *) session_id, 16);
 200         response_type = buffer_get_int(&e->input);
 201         if (response_type != 1)
 202                 goto failure;
 203
 204         private = lookup_private_key(key, NULL, 1);
 205         if (private != NULL) {
 206                 /* Decrypt the challenge using the private key. */
 207                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 208                         goto failure;
 209
 210                 /* The response is MD5 of decrypted challenge plus session id. */
 211                 len = BN_num_bytes(challenge);
 212                 if (len <= 0 || len > 32) {
 213                         log("process_authentication_challenge: bad challenge length %d", len);
 214                         goto failure;
 215                 }
 216                 memset(buf, 0, 32);
 217                 BN_bn2bin(challenge, buf + 32 - len);
 218                 MD5_Init(&md);
 219                 MD5_Update(&md, buf, 32);
 220                 MD5_Update(&md, session_id, 16);
 221                 MD5_Final(mdbuf, &md);
 222
 223                 /* Send the response. */
 224                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 225                 for (i = 0; i < 16; i++)
 226                         buffer_put_char(&msg, mdbuf[i]);
 227                 goto send;
 228         }
 229
 230 failure:
 231         /* Unknown identity or protocol error.  Send failure. */
 232         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 233 send:
 234         buffer_put_int(&e->output, buffer_len(&msg));
 235         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 236         key_free(key);
 237         BN_clear_free(challenge);
 238         buffer_free(&msg);
 239 }
 240
 241 /* ssh2 only */
 242 static void
 243 process_sign_request2(SocketEntry *e)
 244 {
 245         extern int datafellows;
 246         Key *key, *private;
 247         u_char *blob, *data, *signature = NULL;
 248         u_int blen, dlen, slen = 0;
 249         int flags;
 250         Buffer msg;
 251         int ok = -1;
 252
 253         datafellows = 0;
 254
 255         blob = buffer_get_string(&e->input, &blen);
 256         data = buffer_get_string(&e->input, &dlen);
 257
 258         flags = buffer_get_int(&e->input);
 259         if (flags & SSH_AGENT_OLD_SIGNATURE)
 260                 datafellows = SSH_BUG_SIGBLOB;
 261
 262         key = key_from_blob(blob, blen);
 263         if (key != NULL) {
 264                 private = lookup_private_key(key, NULL, 2);
 265                 if (private != NULL)
 266                         ok = key_sign(private, &signature, &slen, data, dlen);
 267         }
 268         key_free(key);
 269         buffer_init(&msg);
 270         if (ok == 0) {
 271                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 272                 buffer_put_string(&msg, signature, slen);
 273         } else {
 274                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 275         }
 276         buffer_put_int(&e->output, buffer_len(&msg));
 277         buffer_append(&e->output, buffer_ptr(&msg),
 278             buffer_len(&msg));
 279         buffer_free(&msg);
 280         xfree(data);
 281         xfree(blob);
 282         if (signature != NULL)
 283                 xfree(signature);
 284 }
 285
 286 /* shared */
 287 static void
 288 process_remove_identity(SocketEntry *e, int version)
 289 {
 290         Key *key = NULL, *private;
 291         u_char *blob;
 292         u_int blen;
 293         u_int bits;
 294         int success = 0;
 295
 296         switch (version) {
 297         case 1:
 298                 key = key_new(KEY_RSA1);
 299                 bits = buffer_get_int(&e->input);
 300                 buffer_get_bignum(&e->input, key->rsa->e);
 301                 buffer_get_bignum(&e->input, key->rsa->n);
 302
 303                 if (bits != key_size(key))
 304                         log("Warning: identity keysize mismatch: actual %d, announced %d",
 305                             key_size(key), bits);
 306                 break;
 307         case 2:
 308                 blob = buffer_get_string(&e->input, &blen);
 309                 key = key_from_blob(blob, blen);
 310                 xfree(blob);
 311                 break;
 312         }
 313         if (key != NULL) {
 314                 int idx;
 315                 private = lookup_private_key(key, &idx, version);
 316                 if (private != NULL) {
 317                         /*
 318                          * We have this key.  Free the old key.  Since we
 319                          * don\'t want to leave empty slots in the middle of
 320                          * the array, we actually free the key there and move
 321                          * all the entries between the empty slot and the end
 322                          * of the array.
 323                          */
 324                         Idtab *tab = idtab_lookup(version);
 325                         key_free(tab->identities[idx].key);
 326                         xfree(tab->identities[idx].comment);
 327                         if (tab->nentries < 1)
 328                                 fatal("process_remove_identity: "
 329                                     "internal error: tab->nentries %d",
 330                                     tab->nentries);
 331                         if (idx != tab->nentries - 1) {
 332                                 int i;
 333                                 for (i = idx; i < tab->nentries - 1; i++)
 334                                         tab->identities[i] = tab->identities[i+1];
 335                         }
 336                         tab->identities[tab->nentries - 1].key = NULL;
 337                         tab->identities[tab->nentries - 1].comment = NULL;
 338                         tab->nentries--;
 339                         success = 1;
 340                 }
 341                 key_free(key);
 342         }
 343         buffer_put_int(&e->output, 1);
 344         buffer_put_char(&e->output,
 345             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 346 }
 347
 348 static void
 349 process_remove_all_identities(SocketEntry *e, int version)
 350 {
 351         u_int i;
 352         Idtab *tab = idtab_lookup(version);
 353
 354         /* Loop over all identities and clear the keys. */
 355         for (i = 0; i < tab->nentries; i++) {
 356                 key_free(tab->identities[i].key);
 357                 xfree(tab->identities[i].comment);
 358         }
 359
 360         /* Mark that there are no identities. */
 361         tab->nentries = 0;
 362
 363         /* Send success. */
 364         buffer_put_int(&e->output, 1);
 365         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 366         return;
 367 }
 368
 369 static void
 370 process_add_identity(SocketEntry *e, int version)
 371 {
 372         Key *k = NULL;
 373         char *type_name;
 374         char *comment;
 375         int type, success = 0;
 376         Idtab *tab = idtab_lookup(version);
 377
 378         switch (version) {
 379         case 1:
 380                 k = key_new_private(KEY_RSA1);
 381                 buffer_get_int(&e->input);                      /* ignored */
 382                 buffer_get_bignum(&e->input, k->rsa->n);
 383                 buffer_get_bignum(&e->input, k->rsa->e);
 384                 buffer_get_bignum(&e->input, k->rsa->d);
 385                 buffer_get_bignum(&e->input, k->rsa->iqmp);
 386
 387                 /* SSH and SSL have p and q swapped */
 388                 buffer_get_bignum(&e->input, k->rsa->q);        /* p */
 389                 buffer_get_bignum(&e->input, k->rsa->p);        /* q */
 390
 391                 /* Generate additional parameters */
 392                 rsa_generate_additional_parameters(k->rsa);
 393                 break;
 394         case 2:
 395                 type_name = buffer_get_string(&e->input, NULL);
 396                 type = key_type_from_name(type_name);
 397                 xfree(type_name);
 398                 switch (type) {
 399                 case KEY_DSA:
 400                         k = key_new_private(type);
 401                         buffer_get_bignum2(&e->input, k->dsa->p);
 402                         buffer_get_bignum2(&e->input, k->dsa->q);
 403                         buffer_get_bignum2(&e->input, k->dsa->g);
 404                         buffer_get_bignum2(&e->input, k->dsa->pub_key);
 405                         buffer_get_bignum2(&e->input, k->dsa->priv_key);
 406                         break;
 407                 case KEY_RSA:
 408                         k = key_new_private(type);
 409                         buffer_get_bignum2(&e->input, k->rsa->n);
 410                         buffer_get_bignum2(&e->input, k->rsa->e);
 411                         buffer_get_bignum2(&e->input, k->rsa->d);
 412                         buffer_get_bignum2(&e->input, k->rsa->iqmp);
 413                         buffer_get_bignum2(&e->input, k->rsa->p);
 414                         buffer_get_bignum2(&e->input, k->rsa->q);
 415
 416                         /* Generate additional parameters */
 417                         rsa_generate_additional_parameters(k->rsa);
 418                         break;
 419                 default:
 420                         buffer_clear(&e->input);
 421                         goto send;
 422                 }
 423                 break;
 424         }
 425         comment = buffer_get_string(&e->input, NULL);
 426         if (k == NULL) {
 427                 xfree(comment);
 428                 goto send;
 429         }
 430         success = 1;
 431         if (lookup_private_key(k, NULL, version) == NULL) {
 432                 if (tab->nentries == 0)
 433                         tab->identities = xmalloc(sizeof(Identity));
 434                 else
 435                         tab->identities = xrealloc(tab->identities,
 436                             (tab->nentries + 1) * sizeof(Identity));
 437                 tab->identities[tab->nentries].key = k;
 438                 tab->identities[tab->nentries].comment = comment;
 439                 /* Increment the number of identities. */
 440                 tab->nentries++;
 441         } else {
 442                 key_free(k);
 443                 xfree(comment);
 444         }
 445 send:
 446         buffer_put_int(&e->output, 1);
 447         buffer_put_char(&e->output,
 448             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 449 }
 450
 451
 452 #ifdef SMARTCARD
 453 static void
 454 process_add_smartcard_key (SocketEntry *e)
 455 {
 456         Idtab *tab;
 457         Key *n = NULL, *k = NULL;
 458         char *sc_reader_id = NULL;
 459         int success = 0;
 460
 461         sc_reader_id = buffer_get_string(&e->input, NULL);
 462         k = sc_get_key(sc_reader_id);
 463         xfree(sc_reader_id);
 464
 465         if (k == NULL) {
 466                 error("sc_get_pubkey failed");
 467                 goto send;
 468         }
 469         success = 1;
 470
 471         tab = idtab_lookup(1);
 472         k->type = KEY_RSA1;
 473         if (lookup_private_key(k, NULL, 1) == NULL) {
 474                 if (tab->nentries == 0)
 475                         tab->identities = xmalloc(sizeof(Identity));
 476                 else
 477                         tab->identities = xrealloc(tab->identities,
 478                             (tab->nentries + 1) * sizeof(Identity));
 479                 n = key_new(KEY_RSA1);
 480                 BN_copy(n->rsa->n, k->rsa->n);
 481                 BN_copy(n->rsa->e, k->rsa->e);
 482                 RSA_set_method(n->rsa, sc_get_engine());
 483                 tab->identities[tab->nentries].key = n;
 484                 tab->identities[tab->nentries].comment =
 485                     xstrdup("rsa1 smartcard");
 486                 tab->nentries++;
 487         }
 488         k->type = KEY_RSA;
 489         tab = idtab_lookup(2);
 490         if (lookup_private_key(k, NULL, 2) == NULL) {
 491                 if (tab->nentries == 0)
 492                         tab->identities = xmalloc(sizeof(Identity));
 493                 else
 494                         tab->identities = xrealloc(tab->identities,
 495                             (tab->nentries + 1) * sizeof(Identity));
 496                 n = key_new(KEY_RSA);
 497                 BN_copy(n->rsa->n, k->rsa->n);
 498                 BN_copy(n->rsa->e, k->rsa->e);
 499                 RSA_set_method(n->rsa, sc_get_engine());
 500                 tab->identities[tab->nentries].key = n;
 501                 tab->identities[tab->nentries].comment =
 502                     xstrdup("rsa smartcard");
 503                 tab->nentries++;
 504         }
 505         key_free(k);
 506 send:
 507         buffer_put_int(&e->output, 1);
 508         buffer_put_char(&e->output,
 509             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 510 }
 511
 512 static void
 513 process_remove_smartcard_key(SocketEntry *e)
 514 {
 515         Key *k = NULL, *private;
 516         int idx;
 517         int success = 0;
 518         char *sc_reader_id = NULL;
 519
 520         sc_reader_id = buffer_get_string(&e->input, NULL);
 521         k = sc_get_key(sc_reader_id);
 522         xfree(sc_reader_id);
 523
 524         if (k == NULL) {
 525                 error("sc_get_pubkey failed");
 526         } else {
 527                 k->type = KEY_RSA1;
 528                 private = lookup_private_key(k, &idx, 1);
 529                 if (private != NULL) {
 530                         Idtab *tab = idtab_lookup(1);
 531                         key_free(tab->identities[idx].key);
 532                         xfree(tab->identities[idx].comment);
 533                         if (idx != tab->nentries)
 534                                 tab->identities[idx] = tab->identities[tab->nentries];
 535                         tab->nentries--;
 536                         success = 1;
 537                 }
 538                 k->type = KEY_RSA;
 539                 private = lookup_private_key(k, &idx, 2);
 540                 if (private != NULL) {
 541                         Idtab *tab = idtab_lookup(2);
 542                         key_free(tab->identities[idx].key);
 543                         xfree(tab->identities[idx].comment);
 544                         if (idx != tab->nentries)
 545                                 tab->identities[idx] = tab->identities[tab->nentries];
 546                         tab->nentries--;
 547                         success = 1;
 548                 }
 549                 key_free(k);
 550         }
 551
 552         buffer_put_int(&e->output, 1);
 553         buffer_put_char(&e->output,
 554             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 555 }
 556 #endif /* SMARTCARD */
 557
 558 /* dispatch incoming messages */
 559
 560 static void
 561 process_message(SocketEntry *e)
 562 {
 563         u_int msg_len;
 564         u_int type;
 565         u_char *cp;
 566         if (buffer_len(&e->input) < 5)
 567                 return;         /* Incomplete message. */
 568         cp = (u_char *) buffer_ptr(&e->input);
 569         msg_len = GET_32BIT(cp);
 570         if (msg_len > 256 * 1024) {
 571                 shutdown(e->fd, SHUT_RDWR);
 572                 close(e->fd);
 573                 e->type = AUTH_UNUSED;
 574                 return;
 575         }
 576         if (buffer_len(&e->input) < msg_len + 4)
 577                 return;
 578         buffer_consume(&e->input, 4);
 579         type = buffer_get_char(&e->input);
 580
 581         debug("type %d", type);
 582         switch (type) {
 583         /* ssh1 */
 584         case SSH_AGENTC_RSA_CHALLENGE:
 585                 process_authentication_challenge1(e);
 586                 break;
 587         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 588                 process_request_identities(e, 1);
 589                 break;
 590         case SSH_AGENTC_ADD_RSA_IDENTITY:
 591                 process_add_identity(e, 1);
 592                 break;
 593         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 594                 process_remove_identity(e, 1);
 595                 break;
 596         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 597                 process_remove_all_identities(e, 1);
 598                 break;
 599         /* ssh2 */
 600         case SSH2_AGENTC_SIGN_REQUEST:
 601                 process_sign_request2(e);
 602                 break;
 603         case SSH2_AGENTC_REQUEST_IDENTITIES:
 604                 process_request_identities(e, 2);
 605                 break;
 606         case SSH2_AGENTC_ADD_IDENTITY:
 607                 process_add_identity(e, 2);
 608                 break;
 609         case SSH2_AGENTC_REMOVE_IDENTITY:
 610                 process_remove_identity(e, 2);
 611                 break;
 612         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 613                 process_remove_all_identities(e, 2);
 614                 break;
 615 #ifdef SMARTCARD
 616         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 617                 process_add_smartcard_key(e);
 618                 break;
 619         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 620                 process_remove_smartcard_key(e);
 621                 break;
 622 #endif /* SMARTCARD */
 623         default:
 624                 /* Unknown message.  Respond with failure. */
 625                 error("Unknown message %d", type);
 626                 buffer_clear(&e->input);
 627                 buffer_put_int(&e->output, 1);
 628                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 629                 break;
 630         }
 631 }
 632
 633 static void
 634 new_socket(sock_type type, int fd)
 635 {
 636         u_int i, old_alloc;
 637         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 638                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 639
 640         if (fd > max_fd)
 641                 max_fd = fd;
 642
 643         for (i = 0; i < sockets_alloc; i++)
 644                 if (sockets[i].type == AUTH_UNUSED) {
 645                         sockets[i].fd = fd;
 646                         sockets[i].type = type;
 647                         buffer_init(&sockets[i].input);
 648                         buffer_init(&sockets[i].output);
 649                         return;
 650                 }
 651         old_alloc = sockets_alloc;
 652         sockets_alloc += 10;
 653         if (sockets)
 654                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 655         else
 656                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 657         for (i = old_alloc; i < sockets_alloc; i++)
 658                 sockets[i].type = AUTH_UNUSED;
 659         sockets[old_alloc].type = type;
 660         sockets[old_alloc].fd = fd;
 661         buffer_init(&sockets[old_alloc].input);
 662         buffer_init(&sockets[old_alloc].output);
 663 }
 664
 665 static int
 666 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 667 {
 668         u_int i, sz;
 669         int n = 0;
 670
 671         for (i = 0; i < sockets_alloc; i++) {
 672                 switch (sockets[i].type) {
 673                 case AUTH_SOCKET:
 674                 case AUTH_CONNECTION:
 675                         n = MAX(n, sockets[i].fd);
 676                         break;
 677                 case AUTH_UNUSED:
 678                         break;
 679                 default:
 680                         fatal("Unknown socket type %d", sockets[i].type);
 681                         break;
 682                 }
 683         }
 684
 685         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 686         if (*fdrp == NULL || sz > *nallocp) {
 687                 if (*fdrp)
 688                         xfree(*fdrp);
 689                 if (*fdwp)
 690                         xfree(*fdwp);
 691                 *fdrp = xmalloc(sz);
 692                 *fdwp = xmalloc(sz);
 693                 *nallocp = sz;
 694         }
 695         if (n < *fdl)
 696                 debug("XXX shrink: %d < %d", n, *fdl);
 697         *fdl = n;
 698         memset(*fdrp, 0, sz);
 699         memset(*fdwp, 0, sz);
 700
 701         for (i = 0; i < sockets_alloc; i++) {
 702                 switch (sockets[i].type) {
 703                 case AUTH_SOCKET:
 704                 case AUTH_CONNECTION:
 705                         FD_SET(sockets[i].fd, *fdrp);
 706                         if (buffer_len(&sockets[i].output) > 0)
 707                                 FD_SET(sockets[i].fd, *fdwp);
 708                         break;
 709                 default:
 710                         break;
 711                 }
 712         }
 713         return (1);
 714 }
 715
 716 static void
 717 after_select(fd_set *readset, fd_set *writeset)
 718 {
 719         u_int i;
 720         int len, sock;
 721         socklen_t slen;
 722         char buf[1024];
 723         struct sockaddr_un sunaddr;
 724
 725         for (i = 0; i < sockets_alloc; i++)
 726                 switch (sockets[i].type) {
 727                 case AUTH_UNUSED:
 728                         break;
 729                 case AUTH_SOCKET:
 730                         if (FD_ISSET(sockets[i].fd, readset)) {
 731                                 slen = sizeof(sunaddr);
 732                                 sock = accept(sockets[i].fd,
 733                                     (struct sockaddr *) &sunaddr, &slen);
 734                                 if (sock < 0) {
 735                                         perror("accept from AUTH_SOCKET");
 736                                         break;
 737                                 }
 738                                 new_socket(AUTH_CONNECTION, sock);
 739                         }
 740                         break;
 741                 case AUTH_CONNECTION:
 742                         if (buffer_len(&sockets[i].output) > 0 &&
 743                             FD_ISSET(sockets[i].fd, writeset)) {
 744                                 do {
 745                                         len = write(sockets[i].fd,
 746                                             buffer_ptr(&sockets[i].output),
 747                                             buffer_len(&sockets[i].output));
 748                                         if (len == -1 && (errno == EAGAIN ||
 749                                             errno == EINTR))
 750                                                 continue;
 751                                         break;
 752                                 } while (1);
 753                                 if (len <= 0) {
 754                                         shutdown(sockets[i].fd, SHUT_RDWR);
 755                                         close(sockets[i].fd);
 756                                         sockets[i].type = AUTH_UNUSED;
 757                                         buffer_free(&sockets[i].input);
 758                                         buffer_free(&sockets[i].output);
 759                                         break;
 760                                 }
 761                                 buffer_consume(&sockets[i].output, len);
 762                         }
 763                         if (FD_ISSET(sockets[i].fd, readset)) {
 764                                 do {
 765                                         len = read(sockets[i].fd, buf, sizeof(buf));
 766                                         if (len == -1 && (errno == EAGAIN ||
 767                                             errno == EINTR))
 768                                                 continue;
 769                                         break;
 770                                 } while (1);
 771                                 if (len <= 0) {
 772                                         shutdown(sockets[i].fd, SHUT_RDWR);
 773                                         close(sockets[i].fd);
 774                                         sockets[i].type = AUTH_UNUSED;
 775                                         buffer_free(&sockets[i].input);
 776                                         buffer_free(&sockets[i].output);
 777                                         break;
 778                                 }
 779                                 buffer_append(&sockets[i].input, buf, len);
 780                                 process_message(&sockets[i]);
 781                         }
 782                         break;
 783                 default:
 784                         fatal("Unknown type %d", sockets[i].type);
 785                 }
 786 }
 787
 788 static void
 789 cleanup_socket(void)
 790 {
 791         if (socket_name[0])
 792                 unlink(socket_name);
 793         if (socket_dir[0])
 794                 rmdir(socket_dir);
 795 }
 796
 797 static void
 798 cleanup_exit(int i)
 799 {
 800         cleanup_socket();
 801         exit(i);
 802 }
 803
 804 static void
 805 cleanup_handler(int sig)
 806 {
 807         cleanup_socket();
 808         _exit(2);
 809 }
 810
 811 static void
 812 check_parent_exists(int sig)
 813 {
 814         int save_errno = errno;
 815
 816         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 817                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 818                 cleanup_handler(sig); /* safe */
 819         }
 820         signal(SIGALRM, check_parent_exists);
 821         alarm(10);
 822         errno = save_errno;
 823 }
 824
 825 static void
 826 usage(void)
 827 {
 828         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 829             __progname);
 830         fprintf(stderr, "Options:\n");
 831         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 832         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 833         fprintf(stderr, "  -k          Kill the current agent.\n");
 834         fprintf(stderr, "  -d          Debug mode.\n");
 835         exit(1);
 836 }
 837
 838 int
 839 main(int ac, char **av)
 840 {
 841         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 842         struct sockaddr_un sunaddr;
 843 #ifdef HAVE_SETRLIMIT
 844         struct rlimit rlim;
 845 #endif
 846 #ifdef HAVE_CYGWIN
 847         int prev_mask;
 848 #endif
 849         pid_t pid;
 850         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 851         extern int optind;
 852         fd_set *readsetp = NULL, *writesetp = NULL;
 853
 854         SSLeay_add_all_algorithms();
 855
 856         __progname = get_progname(av[0]);
 857         init_rng();
 858         seed_rng();
 859
 860 #ifdef __GNU_LIBRARY__
 861         while ((ch = getopt(ac, av, "+cdks")) != -1) {
 862 #else /* __GNU_LIBRARY__ */
 863         while ((ch = getopt(ac, av, "cdks")) != -1) {
 864 #endif /* __GNU_LIBRARY__ */
 865                 switch (ch) {
 866                 case 'c':
 867                         if (s_flag)
 868                                 usage();
 869                         c_flag++;
 870                         break;
 871                 case 'k':
 872                         k_flag++;
 873                         break;
 874                 case 's':
 875                         if (c_flag)
 876                                 usage();
 877                         s_flag++;
 878                         break;
 879                 case 'd':
 880                         if (d_flag)
 881                                 usage();
 882                         d_flag++;
 883                         break;
 884                 default:
 885                         usage();
 886                 }
 887         }
 888         ac -= optind;
 889         av += optind;
 890
 891         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
 892                 usage();
 893
 894         if (ac == 0 && !c_flag && !k_flag && !s_flag && !d_flag) {
 895                 shell = getenv("SHELL");
 896                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 897                         c_flag = 1;
 898         }
 899         if (k_flag) {
 900                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 901                 if (pidstr == NULL) {
 902                         fprintf(stderr, "%s not set, cannot kill agent\n",
 903                             SSH_AGENTPID_ENV_NAME);
 904                         exit(1);
 905                 }
 906                 pid = atoi(pidstr);
 907                 if (pid < 1) {
 908                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 909                             SSH_AGENTPID_ENV_NAME, pidstr);
 910                         exit(1);
 911                 }
 912                 if (kill(pid, SIGTERM) == -1) {
 913                         perror("kill");
 914                         exit(1);
 915                 }
 916                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 917                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 918                 printf(format, SSH_AGENTPID_ENV_NAME);
 919                 printf("echo Agent pid %d killed;\n", pid);
 920                 exit(0);
 921         }
 922         parent_pid = getpid();
 923
 924         /* Create private directory for agent socket */
 925         strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 926         if (mkdtemp(socket_dir) == NULL) {
 927                 perror("mkdtemp: private socket dir");
 928                 exit(1);
 929         }
 930         snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 931             parent_pid);
 932
 933         /*
 934          * Create socket early so it will exist before command gets run from
 935          * the parent.
 936          */
 937         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 938         if (sock < 0) {
 939                 perror("socket");
 940                 cleanup_exit(1);
 941         }
 942         memset(&sunaddr, 0, sizeof(sunaddr));
 943         sunaddr.sun_family = AF_UNIX;
 944         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 945 #ifdef HAVE_CYGWIN
 946         prev_mask = umask(0177);
 947 #endif
 948         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 949                 perror("bind");
 950 #ifdef HAVE_CYGWIN
 951                 umask(prev_mask);
 952 #endif
 953                 cleanup_exit(1);
 954         }
 955 #ifdef HAVE_CYGWIN
 956         umask(prev_mask);
 957 #endif
 958         if (listen(sock, 5) < 0) {
 959                 perror("listen");
 960                 cleanup_exit(1);
 961         }
 962
 963         /*
 964          * Fork, and have the parent execute the command, if any, or present
 965          * the socket data.  The child continues as the authentication agent.
 966          */
 967         if (d_flag) {
 968                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
 969                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 970                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 971                     SSH_AUTHSOCKET_ENV_NAME);
 972                 printf("echo Agent pid %d;\n", parent_pid);
 973                 goto skip;
 974         }
 975         pid = fork();
 976         if (pid == -1) {
 977                 perror("fork");
 978                 exit(1);
 979         }
 980         if (pid != 0) {         /* Parent - execute the given command. */
 981                 close(sock);
 982                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 983                 if (ac == 0) {
 984                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 985                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 986                             SSH_AUTHSOCKET_ENV_NAME);
 987                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 988                             SSH_AGENTPID_ENV_NAME);
 989                         printf("echo Agent pid %d;\n", pid);
 990                         exit(0);
 991                 }
 992                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 993                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 994                         perror("setenv");
 995                         exit(1);
 996                 }
 997                 execvp(av[0], av);
 998                 perror(av[0]);
 999                 exit(1);
1000         }
1001
1002         if (setsid() == -1) {
1003                 perror("setsid");
1004                 cleanup_exit(1);
1005         }
1006
1007         (void)chdir("/");
1008         close(0);
1009         close(1);
1010         close(2);
1011
1012 #ifdef HAVE_SETRLIMIT
1013         /* deny core dumps, since memory contains unencrypted private keys */
1014         rlim.rlim_cur = rlim.rlim_max = 0;
1015         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1016                 perror("setrlimit rlimit_core failed");
1017                 cleanup_exit(1);
1018         }
1019 #endif
1020
1021 skip:
1022         if (atexit(cleanup_socket) < 0) {
1023                 perror("atexit");
1024                 cleanup_exit(1);
1025         }
1026         new_socket(AUTH_SOCKET, sock);
1027         if (ac > 0) {
1028                 signal(SIGALRM, check_parent_exists);
1029                 alarm(10);
1030         }
1031         idtab_init();
1032         if (!d_flag)
1033                 signal(SIGINT, SIG_IGN);
1034         signal(SIGPIPE, SIG_IGN);
1035         signal(SIGHUP, cleanup_handler);
1036         signal(SIGTERM, cleanup_handler);
1037         nalloc = 0;
1038
1039         while (1) {
1040                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1041                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1042                         if (errno == EINTR)
1043                                 continue;
1044                         exit(1);
1045                 }
1046                 after_select(readsetp, writesetp);
1047         }
1048         /* NOTREACHED */
1049 }