openssh/ssh-agent.c

   1 /*      $OpenBSD: ssh-agent.c,v 1.72 2001/08/03 10:31:30 jakob 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 1.72 2001/08/03 10:31:30 jakob 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         char *sc_reader_id = NULL;
 455         int success = 0;
 456
 457         sc_reader_id = buffer_get_string(&e->input, NULL);
 458         k = sc_get_key(sc_reader_id);
 459         xfree(sc_reader_id);
 460
 461         if (k == NULL) {
 462                 error("sc_get_pubkey failed");
 463                 goto send;
 464         }
 465         success = 1;
 466
 467         tab = idtab_lookup(1);
 468         k->type = KEY_RSA1;
 469         if (lookup_private_key(k, NULL, 1) == NULL) {
 470                 if (tab->nentries == 0)
 471                         tab->identities = xmalloc(sizeof(Identity));
 472                 else
 473                         tab->identities = xrealloc(tab->identities,
 474                             (tab->nentries + 1) * sizeof(Identity));
 475                 n = key_new(KEY_RSA1);
 476                 BN_copy(n->rsa->n, k->rsa->n);
 477                 BN_copy(n->rsa->e, k->rsa->e);
 478                 RSA_set_method(n->rsa, sc_get_engine());
 479                 tab->identities[tab->nentries].key = n;
 480                 tab->identities[tab->nentries].comment =
 481                     xstrdup("rsa1 smartcard");
 482                 tab->nentries++;
 483         }
 484         k->type = KEY_RSA;
 485         tab = idtab_lookup(2);
 486         if (lookup_private_key(k, NULL, 2) == NULL) {
 487                 if (tab->nentries == 0)
 488                         tab->identities = xmalloc(sizeof(Identity));
 489                 else
 490                         tab->identities = xrealloc(tab->identities,
 491                             (tab->nentries + 1) * sizeof(Identity));
 492                 n = key_new(KEY_RSA);
 493                 BN_copy(n->rsa->n, k->rsa->n);
 494                 BN_copy(n->rsa->e, k->rsa->e);
 495                 RSA_set_method(n->rsa, sc_get_engine());
 496                 tab->identities[tab->nentries].key = n;
 497                 tab->identities[tab->nentries].comment =
 498                     xstrdup("rsa smartcard");
 499                 tab->nentries++;
 500         }
 501         key_free(k);
 502 send:
 503         buffer_put_int(&e->output, 1);
 504         buffer_put_char(&e->output,
 505             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 506 }
 507
 508 static void
 509 process_remove_smartcard_key(SocketEntry *e)
 510 {
 511         Key *k = NULL, *private;
 512         int idx;
 513         int success = 0;
 514         char *sc_reader_id = NULL;
 515
 516         sc_reader_id = buffer_get_string(&e->input, NULL);
 517         k = sc_get_key(sc_reader_id);
 518         xfree(sc_reader_id);
 519
 520         if (k == NULL) {
 521                 error("sc_get_pubkey failed");
 522         } else {
 523                 k->type = KEY_RSA1;
 524                 private = lookup_private_key(k, &idx, 1);
 525                 if (private != NULL) {
 526                         Idtab *tab = idtab_lookup(1);
 527                         key_free(tab->identities[idx].key);
 528                         xfree(tab->identities[idx].comment);
 529                         if (idx != tab->nentries)
 530                                 tab->identities[idx] = tab->identities[tab->nentries];
 531                         tab->nentries--;
 532                         success = 1;
 533                 }
 534                 k->type = KEY_RSA;
 535                 private = lookup_private_key(k, &idx, 2);
 536                 if (private != NULL) {
 537                         Idtab *tab = idtab_lookup(2);
 538                         key_free(tab->identities[idx].key);
 539                         xfree(tab->identities[idx].comment);
 540                         if (idx != tab->nentries)
 541                                 tab->identities[idx] = tab->identities[tab->nentries];
 542                         tab->nentries--;
 543                         success = 1;
 544                 }
 545                 key_free(k);
 546         }
 547
 548         buffer_put_int(&e->output, 1);
 549         buffer_put_char(&e->output,
 550             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 551 }
 552 #endif /* SMARTCARD */
 553
 554 /* dispatch incoming messages */
 555
 556 static void
 557 process_message(SocketEntry *e)
 558 {
 559         u_int msg_len;
 560         u_int type;
 561         u_char *cp;
 562         if (buffer_len(&e->input) < 5)
 563                 return;         /* Incomplete message. */
 564         cp = (u_char *) buffer_ptr(&e->input);
 565         msg_len = GET_32BIT(cp);
 566         if (msg_len > 256 * 1024) {
 567                 shutdown(e->fd, SHUT_RDWR);
 568                 close(e->fd);
 569                 e->type = AUTH_UNUSED;
 570                 return;
 571         }
 572         if (buffer_len(&e->input) < msg_len + 4)
 573                 return;
 574         buffer_consume(&e->input, 4);
 575         type = buffer_get_char(&e->input);
 576
 577         debug("type %d", type);
 578         switch (type) {
 579         /* ssh1 */
 580         case SSH_AGENTC_RSA_CHALLENGE:
 581                 process_authentication_challenge1(e);
 582                 break;
 583         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 584                 process_request_identities(e, 1);
 585                 break;
 586         case SSH_AGENTC_ADD_RSA_IDENTITY:
 587                 process_add_identity(e, 1);
 588                 break;
 589         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 590                 process_remove_identity(e, 1);
 591                 break;
 592         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 593                 process_remove_all_identities(e, 1);
 594                 break;
 595         /* ssh2 */
 596         case SSH2_AGENTC_SIGN_REQUEST:
 597                 process_sign_request2(e);
 598                 break;
 599         case SSH2_AGENTC_REQUEST_IDENTITIES:
 600                 process_request_identities(e, 2);
 601                 break;
 602         case SSH2_AGENTC_ADD_IDENTITY:
 603                 process_add_identity(e, 2);
 604                 break;
 605         case SSH2_AGENTC_REMOVE_IDENTITY:
 606                 process_remove_identity(e, 2);
 607                 break;
 608         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 609                 process_remove_all_identities(e, 2);
 610                 break;
 611 #ifdef SMARTCARD
 612         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 613                 process_add_smartcard_key(e);
 614                 break;
 615         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 616                 process_remove_smartcard_key(e);
 617                 break;
 618 #endif /* SMARTCARD */
 619         default:
 620                 /* Unknown message.  Respond with failure. */
 621                 error("Unknown message %d", type);
 622                 buffer_clear(&e->input);
 623                 buffer_put_int(&e->output, 1);
 624                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 625                 break;
 626         }
 627 }
 628
 629 static void
 630 new_socket(int type, int fd)
 631 {
 632         u_int i, old_alloc;
 633         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 634                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 635
 636         if (fd > max_fd)
 637                 max_fd = fd;
 638
 639         for (i = 0; i < sockets_alloc; i++)
 640                 if (sockets[i].type == AUTH_UNUSED) {
 641                         sockets[i].fd = fd;
 642                         sockets[i].type = type;
 643                         buffer_init(&sockets[i].input);
 644                         buffer_init(&sockets[i].output);
 645                         return;
 646                 }
 647         old_alloc = sockets_alloc;
 648         sockets_alloc += 10;
 649         if (sockets)
 650                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 651         else
 652                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 653         for (i = old_alloc; i < sockets_alloc; i++)
 654                 sockets[i].type = AUTH_UNUSED;
 655         sockets[old_alloc].type = type;
 656         sockets[old_alloc].fd = fd;
 657         buffer_init(&sockets[old_alloc].input);
 658         buffer_init(&sockets[old_alloc].output);
 659 }
 660
 661 static int
 662 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 663 {
 664         u_int i, sz;
 665         int n = 0;
 666
 667         for (i = 0; i < sockets_alloc; i++) {
 668                 switch (sockets[i].type) {
 669                 case AUTH_SOCKET:
 670                 case AUTH_CONNECTION:
 671                         n = MAX(n, sockets[i].fd);
 672                         break;
 673                 case AUTH_UNUSED:
 674                         break;
 675                 default:
 676                         fatal("Unknown socket type %d", sockets[i].type);
 677                         break;
 678                 }
 679         }
 680
 681         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 682         if (*fdrp == NULL || sz > *nallocp) {
 683                 if (*fdrp)
 684                         xfree(*fdrp);
 685                 if (*fdwp)
 686                         xfree(*fdwp);
 687                 *fdrp = xmalloc(sz);
 688                 *fdwp = xmalloc(sz);
 689                 *nallocp = sz;
 690         }
 691         if (n < *fdl)
 692                 debug("XXX shrink: %d < %d", n, *fdl);
 693         *fdl = n;
 694         memset(*fdrp, 0, sz);
 695         memset(*fdwp, 0, sz);
 696
 697         for (i = 0; i < sockets_alloc; i++) {
 698                 switch (sockets[i].type) {
 699                 case AUTH_SOCKET:
 700                 case AUTH_CONNECTION:
 701                         FD_SET(sockets[i].fd, *fdrp);
 702                         if (buffer_len(&sockets[i].output) > 0)
 703                                 FD_SET(sockets[i].fd, *fdwp);
 704                         break;
 705                 default:
 706                         break;
 707                 }
 708         }
 709         return (1);
 710 }
 711
 712 static void
 713 after_select(fd_set *readset, fd_set *writeset)
 714 {
 715         u_int i;
 716         int len, sock;
 717         socklen_t slen;
 718         char buf[1024];
 719         struct sockaddr_un sunaddr;
 720
 721         for (i = 0; i < sockets_alloc; i++)
 722                 switch (sockets[i].type) {
 723                 case AUTH_UNUSED:
 724                         break;
 725                 case AUTH_SOCKET:
 726                         if (FD_ISSET(sockets[i].fd, readset)) {
 727                                 slen = sizeof(sunaddr);
 728                                 sock = accept(sockets[i].fd,
 729                                     (struct sockaddr *) &sunaddr, &slen);
 730                                 if (sock < 0) {
 731                                         perror("accept from AUTH_SOCKET");
 732                                         break;
 733                                 }
 734                                 new_socket(AUTH_CONNECTION, sock);
 735                         }
 736                         break;
 737                 case AUTH_CONNECTION:
 738                         if (buffer_len(&sockets[i].output) > 0 &&
 739                             FD_ISSET(sockets[i].fd, writeset)) {
 740                                 do {
 741                                         len = write(sockets[i].fd,
 742                                             buffer_ptr(&sockets[i].output),
 743                                             buffer_len(&sockets[i].output));
 744                                         if (len == -1 && (errno == EAGAIN ||
 745                                             errno == EINTR))
 746                                                 continue;
 747                                         break;
 748                                 } while (1);
 749                                 if (len <= 0) {
 750                                         shutdown(sockets[i].fd, SHUT_RDWR);
 751                                         close(sockets[i].fd);
 752                                         sockets[i].type = AUTH_UNUSED;
 753                                         buffer_free(&sockets[i].input);
 754                                         buffer_free(&sockets[i].output);
 755                                         break;
 756                                 }
 757                                 buffer_consume(&sockets[i].output, len);
 758                         }
 759                         if (FD_ISSET(sockets[i].fd, readset)) {
 760                                 do {
 761                                         len = read(sockets[i].fd, buf, sizeof(buf));
 762                                         if (len == -1 && (errno == EAGAIN ||
 763                                             errno == EINTR))
 764                                                 continue;
 765                                         break;
 766                                 } while (1);
 767                                 if (len <= 0) {
 768                                         shutdown(sockets[i].fd, SHUT_RDWR);
 769                                         close(sockets[i].fd);
 770                                         sockets[i].type = AUTH_UNUSED;
 771                                         buffer_free(&sockets[i].input);
 772                                         buffer_free(&sockets[i].output);
 773                                         break;
 774                                 }
 775                                 buffer_append(&sockets[i].input, buf, len);
 776                                 process_message(&sockets[i]);
 777                         }
 778                         break;
 779                 default:
 780                         fatal("Unknown type %d", sockets[i].type);
 781                 }
 782 }
 783
 784 static void
 785 cleanup_socket(void)
 786 {
 787         if (socket_name[0])
 788                 unlink(socket_name);
 789         if (socket_dir[0])
 790                 rmdir(socket_dir);
 791 }
 792
 793 static void
 794 cleanup_exit(int i)
 795 {
 796         cleanup_socket();
 797         exit(i);
 798 }
 799
 800 static void
 801 cleanup_handler(int sig)
 802 {
 803         cleanup_socket();
 804         _exit(2);
 805 }
 806
 807 static void
 808 check_parent_exists(int sig)
 809 {
 810         int save_errno = errno;
 811
 812         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 813                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 814                 cleanup_handler(sig); /* safe */
 815         }
 816         signal(SIGALRM, check_parent_exists);
 817         alarm(10);
 818         errno = save_errno;
 819 }
 820
 821 static void
 822 usage(void)
 823 {
 824         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 825             __progname);
 826         fprintf(stderr, "Options:\n");
 827         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 828         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 829         fprintf(stderr, "  -k          Kill the current agent.\n");
 830         fprintf(stderr, "  -d          Debug mode.\n");
 831         exit(1);
 832 }
 833
 834 int
 835 main(int ac, char **av)
 836 {
 837         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 838         struct sockaddr_un sunaddr;
 839 #ifdef HAVE_SETRLIMIT
 840         struct rlimit rlim;
 841 #endif
 842 #ifdef HAVE_CYGWIN
 843         int prev_mask;
 844 #endif
 845         pid_t pid;
 846         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 847         extern int optind;
 848         fd_set *readsetp = NULL, *writesetp = NULL;
 849
 850         SSLeay_add_all_algorithms();
 851
 852         __progname = get_progname(av[0]);
 853         init_rng();
 854         seed_rng();
 855
 856 #ifdef __GNU_LIBRARY__
 857         while ((ch = getopt(ac, av, "+cdks")) != -1) {
 858 #else /* __GNU_LIBRARY__ */
 859         while ((ch = getopt(ac, av, "cdks")) != -1) {
 860 #endif /* __GNU_LIBRARY__ */
 861                 switch (ch) {
 862                 case 'c':
 863                         if (s_flag)
 864                                 usage();
 865                         c_flag++;
 866                         break;
 867                 case 'k':
 868                         k_flag++;
 869                         break;
 870                 case 's':
 871                         if (c_flag)
 872                                 usage();
 873                         s_flag++;
 874                         break;
 875                 case 'd':
 876                         if (d_flag)
 877                                 usage();
 878                         d_flag++;
 879                         break;
 880                 default:
 881                         usage();
 882                 }
 883         }
 884         ac -= optind;
 885         av += optind;
 886
 887         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
 888                 usage();
 889
 890         if (ac == 0 && !c_flag && !k_flag && !s_flag && !d_flag) {
 891                 shell = getenv("SHELL");
 892                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 893                         c_flag = 1;
 894         }
 895         if (k_flag) {
 896                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 897                 if (pidstr == NULL) {
 898                         fprintf(stderr, "%s not set, cannot kill agent\n",
 899                             SSH_AGENTPID_ENV_NAME);
 900                         exit(1);
 901                 }
 902                 pid = atoi(pidstr);
 903                 if (pid < 1) {
 904                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 905                             SSH_AGENTPID_ENV_NAME, pidstr);
 906                         exit(1);
 907                 }
 908                 if (kill(pid, SIGTERM) == -1) {
 909                         perror("kill");
 910                         exit(1);
 911                 }
 912                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 913                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 914                 printf(format, SSH_AGENTPID_ENV_NAME);
 915                 printf("echo Agent pid %d killed;\n", pid);
 916                 exit(0);
 917         }
 918         parent_pid = getpid();
 919
 920         /* Create private directory for agent socket */
 921         strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 922         if (mkdtemp(socket_dir) == NULL) {
 923                 perror("mkdtemp: private socket dir");
 924                 exit(1);
 925         }
 926         snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 927             parent_pid);
 928
 929         /*
 930          * Create socket early so it will exist before command gets run from
 931          * the parent.
 932          */
 933         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 934         if (sock < 0) {
 935                 perror("socket");
 936                 cleanup_exit(1);
 937         }
 938         memset(&sunaddr, 0, sizeof(sunaddr));
 939         sunaddr.sun_family = AF_UNIX;
 940         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 941 #ifdef HAVE_CYGWIN
 942         prev_mask = umask(0177);
 943 #endif
 944         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 945                 perror("bind");
 946 #ifdef HAVE_CYGWIN
 947                 umask(prev_mask);
 948 #endif
 949                 cleanup_exit(1);
 950         }
 951 #ifdef HAVE_CYGWIN
 952         umask(prev_mask);
 953 #endif
 954         if (listen(sock, 5) < 0) {
 955                 perror("listen");
 956                 cleanup_exit(1);
 957         }
 958
 959         /*
 960          * Fork, and have the parent execute the command, if any, or present
 961          * the socket data.  The child continues as the authentication agent.
 962          */
 963         if (d_flag) {
 964                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
 965                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 966                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 967                     SSH_AUTHSOCKET_ENV_NAME);
 968                 printf("echo Agent pid %d;\n", parent_pid);
 969                 goto skip;
 970         }
 971         pid = fork();
 972         if (pid == -1) {
 973                 perror("fork");
 974                 exit(1);
 975         }
 976         if (pid != 0) {         /* Parent - execute the given command. */
 977                 close(sock);
 978                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 979                 if (ac == 0) {
 980                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 981                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 982                             SSH_AUTHSOCKET_ENV_NAME);
 983                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 984                             SSH_AGENTPID_ENV_NAME);
 985                         printf("echo Agent pid %d;\n", pid);
 986                         exit(0);
 987                 }
 988                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 989                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 990                         perror("setenv");
 991                         exit(1);
 992                 }
 993                 execvp(av[0], av);
 994                 perror(av[0]);
 995                 exit(1);
 996         }
 997
 998         if (setsid() == -1) {
 999                 perror("setsid");
1000                 cleanup_exit(1);
1001         }
1002
1003         (void)chdir("/");
1004         close(0);
1005         close(1);
1006         close(2);
1007
1008 #ifdef HAVE_SETRLIMIT
1009         /* deny core dumps, since memory contains unencrypted private keys */
1010         rlim.rlim_cur = rlim.rlim_max = 0;
1011         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1012                 perror("setrlimit rlimit_core failed");
1013                 cleanup_exit(1);
1014         }
1015 #endif
1016
1017 skip:
1018         if (atexit(cleanup_socket) < 0) {
1019                 perror("atexit");
1020                 cleanup_exit(1);
1021         }
1022         new_socket(AUTH_SOCKET, sock);
1023         if (ac > 0) {
1024                 signal(SIGALRM, check_parent_exists);
1025                 alarm(10);
1026         }
1027         idtab_init();
1028         if (!d_flag)
1029                 signal(SIGINT, SIG_IGN);
1030         signal(SIGPIPE, SIG_IGN);
1031         signal(SIGHUP, cleanup_handler);
1032         signal(SIGTERM, cleanup_handler);
1033         nalloc = 0;
1034
1035         while (1) {
1036                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1037                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1038                         if (errno == EINTR)
1039                                 continue;
1040                         exit(1);
1041                 }
1042                 after_select(readsetp, writesetp);
1043         }
1044         /* NOTREACHED */
1045 }