ssh-agent.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * The authentication agent program.
   6  *
   7  * As far as I am concerned, the code I have written for this software
   8  * can be used freely for any purpose.  Any derived versions of this
   9  * software must be clearly marked as such, and if the derived work is
  10  * incompatible with the protocol description in the RFC file, it must be
  11  * called by a name other than "ssh" or "Secure Shell".
  12  *
  13  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  14  *
  15  * Redistribution and use in source and binary forms, with or without
  16  * modification, are permitted provided that the following conditions
  17  * are met:
  18  * 1. Redistributions of source code must retain the above copyright
  19  *    notice, this list of conditions and the following disclaimer.
  20  * 2. Redistributions in binary form must reproduce the above copyright
  21  *    notice, this list of conditions and the following disclaimer in the
  22  *    documentation and/or other materials provided with the distribution.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  27  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  28  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  29  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  30  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  31  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  32  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  33  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 #include "includes.h"
  37 RCSID("$OpenBSD: ssh-agent.c,v 1.83 2002/03/21 22:44:05 rees Exp $");
  38
  39 #if defined(HAVE_SYS_QUEUE_H) && !defined(HAVE_BOGUS_SYS_QUEUE_H)
  40 #include <sys/queue.h>
  41 #else
  42 #include "openbsd-compat/fake-queue.h"
  43 #endif
  44
  45 #include <openssl/evp.h>
  46 #include <openssl/md5.h>
  47
  48 #include "ssh.h"
  49 #include "rsa.h"
  50 #include "buffer.h"
  51 #include "bufaux.h"
  52 #include "xmalloc.h"
  53 #include "getput.h"
  54 #include "key.h"
  55 #include "authfd.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 identity {
  81         TAILQ_ENTRY(identity) next;
  82         Key *key;
  83         char *comment;
  84 } Identity;
  85
  86 typedef struct {
  87         int nentries;
  88         TAILQ_HEAD(idqueue, identity) idlist;
  89 } Idtab;
  90
  91 /* private key table, one per protocol version */
  92 Idtab idtable[3];
  93
  94 int max_fd = 0;
  95
  96 /* pid of shell == parent of agent */
  97 pid_t parent_pid = -1;
  98
  99 /* pathname and directory for AUTH_SOCKET */
 100 char socket_name[1024];
 101 char socket_dir[1024];
 102
 103 #ifdef HAVE___PROGNAME
 104 extern char *__progname;
 105 #else
 106 char *__progname;
 107 #endif
 108
 109 static void
 110 idtab_init(void)
 111 {
 112         int i;
 113         for (i = 0; i <=2; i++) {
 114                 TAILQ_INIT(&idtable[i].idlist);
 115                 idtable[i].nentries = 0;
 116         }
 117 }
 118
 119 /* return private key table for requested protocol version */
 120 static Idtab *
 121 idtab_lookup(int version)
 122 {
 123         if (version < 1 || version > 2)
 124                 fatal("internal error, bad protocol version %d", version);
 125         return &idtable[version];
 126 }
 127
 128 /* return matching private key for given public key */
 129 static Identity *
 130 lookup_identity(Key *key, int version)
 131 {
 132         Identity *id;
 133
 134         Idtab *tab = idtab_lookup(version);
 135         TAILQ_FOREACH(id, &tab->idlist, next) {
 136                 if (key_equal(key, id->key))
 137                         return (id);
 138         }
 139         return (NULL);
 140 }
 141
 142 static void
 143 free_identity(Identity *id)
 144 {
 145         key_free(id->key);
 146         xfree(id->comment);
 147         xfree(id);
 148 }
 149
 150 /* send list of supported public keys to 'client' */
 151 static void
 152 process_request_identities(SocketEntry *e, int version)
 153 {
 154         Idtab *tab = idtab_lookup(version);
 155         Buffer msg;
 156         Identity *id;
 157
 158         buffer_init(&msg);
 159         buffer_put_char(&msg, (version == 1) ?
 160             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 161         buffer_put_int(&msg, tab->nentries);
 162         TAILQ_FOREACH(id, &tab->idlist, next) {
 163                 if (id->key->type == KEY_RSA1) {
 164                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 165                         buffer_put_bignum(&msg, id->key->rsa->e);
 166                         buffer_put_bignum(&msg, id->key->rsa->n);
 167                 } else {
 168                         u_char *blob;
 169                         u_int blen;
 170                         key_to_blob(id->key, &blob, &blen);
 171                         buffer_put_string(&msg, blob, blen);
 172                         xfree(blob);
 173                 }
 174                 buffer_put_cstring(&msg, id->comment);
 175         }
 176         buffer_put_int(&e->output, buffer_len(&msg));
 177         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 178         buffer_free(&msg);
 179 }
 180
 181 /* ssh1 only */
 182 static void
 183 process_authentication_challenge1(SocketEntry *e)
 184 {
 185         Identity *id;
 186         Key *key;
 187         BIGNUM *challenge;
 188         int i, len;
 189         Buffer msg;
 190         MD5_CTX md;
 191         u_char buf[32], mdbuf[16], session_id[16];
 192         u_int response_type;
 193
 194         buffer_init(&msg);
 195         key = key_new(KEY_RSA1);
 196         if ((challenge = BN_new()) == NULL)
 197                 fatal("process_authentication_challenge1: BN_new failed");
 198
 199         buffer_get_int(&e->input);                              /* ignored */
 200         buffer_get_bignum(&e->input, key->rsa->e);
 201         buffer_get_bignum(&e->input, key->rsa->n);
 202         buffer_get_bignum(&e->input, challenge);
 203
 204         /* Only protocol 1.1 is supported */
 205         if (buffer_len(&e->input) == 0)
 206                 goto failure;
 207         buffer_get(&e->input, session_id, 16);
 208         response_type = buffer_get_int(&e->input);
 209         if (response_type != 1)
 210                 goto failure;
 211
 212         id = lookup_identity(key, 1);
 213         if (id != NULL) {
 214                 Key *private = id->key;
 215                 /* Decrypt the challenge using the private key. */
 216                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 217                         goto failure;
 218
 219                 /* The response is MD5 of decrypted challenge plus session id. */
 220                 len = BN_num_bytes(challenge);
 221                 if (len <= 0 || len > 32) {
 222                         log("process_authentication_challenge: bad challenge length %d", len);
 223                         goto failure;
 224                 }
 225                 memset(buf, 0, 32);
 226                 BN_bn2bin(challenge, buf + 32 - len);
 227                 MD5_Init(&md);
 228                 MD5_Update(&md, buf, 32);
 229                 MD5_Update(&md, session_id, 16);
 230                 MD5_Final(mdbuf, &md);
 231
 232                 /* Send the response. */
 233                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 234                 for (i = 0; i < 16; i++)
 235                         buffer_put_char(&msg, mdbuf[i]);
 236                 goto send;
 237         }
 238
 239 failure:
 240         /* Unknown identity or protocol error.  Send failure. */
 241         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 242 send:
 243         buffer_put_int(&e->output, buffer_len(&msg));
 244         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 245         key_free(key);
 246         BN_clear_free(challenge);
 247         buffer_free(&msg);
 248 }
 249
 250 /* ssh2 only */
 251 static void
 252 process_sign_request2(SocketEntry *e)
 253 {
 254         extern int datafellows;
 255         Key *key;
 256         u_char *blob, *data, *signature = NULL;
 257         u_int blen, dlen, slen = 0;
 258         int flags;
 259         Buffer msg;
 260         int ok = -1;
 261
 262         datafellows = 0;
 263
 264         blob = buffer_get_string(&e->input, &blen);
 265         data = buffer_get_string(&e->input, &dlen);
 266
 267         flags = buffer_get_int(&e->input);
 268         if (flags & SSH_AGENT_OLD_SIGNATURE)
 269                 datafellows = SSH_BUG_SIGBLOB;
 270
 271         key = key_from_blob(blob, blen);
 272         if (key != NULL) {
 273                 Identity *id = lookup_identity(key, 2);
 274                 if (id != NULL)
 275                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 276         }
 277         key_free(key);
 278         buffer_init(&msg);
 279         if (ok == 0) {
 280                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 281                 buffer_put_string(&msg, signature, slen);
 282         } else {
 283                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 284         }
 285         buffer_put_int(&e->output, buffer_len(&msg));
 286         buffer_append(&e->output, buffer_ptr(&msg),
 287             buffer_len(&msg));
 288         buffer_free(&msg);
 289         xfree(data);
 290         xfree(blob);
 291         if (signature != NULL)
 292                 xfree(signature);
 293 }
 294
 295 /* shared */
 296 static void
 297 process_remove_identity(SocketEntry *e, int version)
 298 {
 299         Key *key = NULL;
 300         u_char *blob;
 301         u_int blen;
 302         u_int bits;
 303         int success = 0;
 304
 305         switch (version) {
 306         case 1:
 307                 key = key_new(KEY_RSA1);
 308                 bits = buffer_get_int(&e->input);
 309                 buffer_get_bignum(&e->input, key->rsa->e);
 310                 buffer_get_bignum(&e->input, key->rsa->n);
 311
 312                 if (bits != key_size(key))
 313                         log("Warning: identity keysize mismatch: actual %d, announced %d",
 314                             key_size(key), bits);
 315                 break;
 316         case 2:
 317                 blob = buffer_get_string(&e->input, &blen);
 318                 key = key_from_blob(blob, blen);
 319                 xfree(blob);
 320                 break;
 321         }
 322         if (key != NULL) {
 323                 Identity *id = lookup_identity(key, version);
 324                 if (id != NULL) {
 325                         /*
 326                          * We have this key.  Free the old key.  Since we
 327                          * don\'t want to leave empty slots in the middle of
 328                          * the array, we actually free the key there and move
 329                          * all the entries between the empty slot and the end
 330                          * of the array.
 331                          */
 332                         Idtab *tab = idtab_lookup(version);
 333                         if (tab->nentries < 1)
 334                                 fatal("process_remove_identity: "
 335                                     "internal error: tab->nentries %d",
 336                                     tab->nentries);
 337                         TAILQ_REMOVE(&tab->idlist, id, next);
 338                         free_identity(id);
 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         Idtab *tab = idtab_lookup(version);
 353         Identity *id;
 354
 355         /* Loop over all identities and clear the keys. */
 356         for (id = TAILQ_FIRST(&tab->idlist); id;
 357             id = TAILQ_FIRST(&tab->idlist)) {
 358                 TAILQ_REMOVE(&tab->idlist, id, next);
 359                 free_identity(id);
 360         }
 361
 362         /* Mark that there are no identities. */
 363         tab->nentries = 0;
 364
 365         /* Send success. */
 366         buffer_put_int(&e->output, 1);
 367         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 368         return;
 369 }
 370
 371 static void
 372 process_add_identity(SocketEntry *e, int version)
 373 {
 374         Key *k = NULL;
 375         char *type_name;
 376         char *comment;
 377         int type, success = 0;
 378         Idtab *tab = idtab_lookup(version);
 379
 380         switch (version) {
 381         case 1:
 382                 k = key_new_private(KEY_RSA1);
 383                 buffer_get_int(&e->input);                      /* ignored */
 384                 buffer_get_bignum(&e->input, k->rsa->n);
 385                 buffer_get_bignum(&e->input, k->rsa->e);
 386                 buffer_get_bignum(&e->input, k->rsa->d);
 387                 buffer_get_bignum(&e->input, k->rsa->iqmp);
 388
 389                 /* SSH and SSL have p and q swapped */
 390                 buffer_get_bignum(&e->input, k->rsa->q);        /* p */
 391                 buffer_get_bignum(&e->input, k->rsa->p);        /* q */
 392
 393                 /* Generate additional parameters */
 394                 rsa_generate_additional_parameters(k->rsa);
 395                 break;
 396         case 2:
 397                 type_name = buffer_get_string(&e->input, NULL);
 398                 type = key_type_from_name(type_name);
 399                 xfree(type_name);
 400                 switch (type) {
 401                 case KEY_DSA:
 402                         k = key_new_private(type);
 403                         buffer_get_bignum2(&e->input, k->dsa->p);
 404                         buffer_get_bignum2(&e->input, k->dsa->q);
 405                         buffer_get_bignum2(&e->input, k->dsa->g);
 406                         buffer_get_bignum2(&e->input, k->dsa->pub_key);
 407                         buffer_get_bignum2(&e->input, k->dsa->priv_key);
 408                         break;
 409                 case KEY_RSA:
 410                         k = key_new_private(type);
 411                         buffer_get_bignum2(&e->input, k->rsa->n);
 412                         buffer_get_bignum2(&e->input, k->rsa->e);
 413                         buffer_get_bignum2(&e->input, k->rsa->d);
 414                         buffer_get_bignum2(&e->input, k->rsa->iqmp);
 415                         buffer_get_bignum2(&e->input, k->rsa->p);
 416                         buffer_get_bignum2(&e->input, k->rsa->q);
 417
 418                         /* Generate additional parameters */
 419                         rsa_generate_additional_parameters(k->rsa);
 420                         break;
 421                 default:
 422                         buffer_clear(&e->input);
 423                         goto send;
 424                 }
 425                 break;
 426         }
 427         comment = buffer_get_string(&e->input, NULL);
 428         if (k == NULL) {
 429                 xfree(comment);
 430                 goto send;
 431         }
 432         success = 1;
 433         if (lookup_identity(k, version) == NULL) {
 434                 Identity *id = xmalloc(sizeof(Identity));
 435                 id->key = k;
 436                 id->comment = comment;
 437                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 438                 /* Increment the number of identities. */
 439                 tab->nentries++;
 440         } else {
 441                 key_free(k);
 442                 xfree(comment);
 443         }
 444 send:
 445         buffer_put_int(&e->output, 1);
 446         buffer_put_char(&e->output,
 447             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 448 }
 449
 450
 451 #ifdef SMARTCARD
 452 static void
 453 process_add_smartcard_key (SocketEntry *e)
 454 {
 455         Idtab *tab;
 456         Key *n = NULL, *k = NULL;
 457         char *sc_reader_id = NULL, *pin;
 458         int success = 0;
 459
 460         sc_reader_id = buffer_get_string(&e->input, NULL);
 461         pin = buffer_get_string(&e->input, NULL);
 462         k = sc_get_key(sc_reader_id, pin);
 463         xfree(sc_reader_id);
 464         xfree(pin);
 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_identity(k, 1) == NULL) {
 475                 Identity *id = xmalloc(sizeof(Identity));
 476                 n = key_new(KEY_RSA1);
 477                 BN_copy(n->rsa->n, k->rsa->n);
 478                 BN_copy(n->rsa->e, k->rsa->e);
 479                 RSA_set_method(n->rsa, sc_get_engine());
 480                 id->key = n;
 481                 id->comment = xstrdup("rsa1 smartcard");
 482                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 483                 tab->nentries++;
 484         }
 485         k->type = KEY_RSA;
 486         tab = idtab_lookup(2);
 487         if (lookup_identity(k, 2) == NULL) {
 488                 Identity *id = xmalloc(sizeof(Identity));
 489                 n = key_new(KEY_RSA);
 490                 BN_copy(n->rsa->n, k->rsa->n);
 491                 BN_copy(n->rsa->e, k->rsa->e);
 492                 RSA_set_method(n->rsa, sc_get_engine());
 493                 id->key = n;
 494                 id->comment = xstrdup("rsa smartcard");
 495                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 496                 tab->nentries++;
 497         }
 498         key_free(k);
 499 send:
 500         buffer_put_int(&e->output, 1);
 501         buffer_put_char(&e->output,
 502             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 503 }
 504
 505 static void
 506 process_remove_smartcard_key(SocketEntry *e)
 507 {
 508         Key *k = NULL;
 509         int success = 0;
 510         char *sc_reader_id = NULL, *pin;
 511
 512         sc_reader_id = buffer_get_string(&e->input, NULL);
 513         pin = buffer_get_string(&e->input, NULL);
 514         k = sc_get_key(sc_reader_id, pin);
 515         xfree(sc_reader_id);
 516         xfree(pin);
 517
 518         if (k == NULL) {
 519                 error("sc_get_pubkey failed");
 520         } else {
 521                 Identity *id;
 522                 k->type = KEY_RSA1;
 523                 id = lookup_identity(k, 1);
 524                 if (id != NULL) {
 525                         Idtab *tab = idtab_lookup(1);
 526                         TAILQ_REMOVE(&tab->idlist, id, next);
 527                         free_identity(id);
 528                         tab->nentries--;
 529                         success = 1;
 530                 }
 531                 k->type = KEY_RSA;
 532                 id = lookup_identity(k, 2);
 533                 if (id != NULL) {
 534                         Idtab *tab = idtab_lookup(2);
 535                         TAILQ_REMOVE(&tab->idlist, id, next);
 536                         free_identity(id);
 537                         tab->nentries--;
 538                         success = 1;
 539                 }
 540                 key_free(k);
 541         }
 542
 543         buffer_put_int(&e->output, 1);
 544         buffer_put_char(&e->output,
 545             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 546 }
 547 #endif /* SMARTCARD */
 548
 549 /* dispatch incoming messages */
 550
 551 static void
 552 process_message(SocketEntry *e)
 553 {
 554         u_int msg_len;
 555         u_int type;
 556         u_char *cp;
 557         if (buffer_len(&e->input) < 5)
 558                 return;         /* Incomplete message. */
 559         cp = buffer_ptr(&e->input);
 560         msg_len = GET_32BIT(cp);
 561         if (msg_len > 256 * 1024) {
 562                 shutdown(e->fd, SHUT_RDWR);
 563                 close(e->fd);
 564                 e->type = AUTH_UNUSED;
 565                 return;
 566         }
 567         if (buffer_len(&e->input) < msg_len + 4)
 568                 return;
 569         buffer_consume(&e->input, 4);
 570         type = buffer_get_char(&e->input);
 571
 572         debug("type %d", type);
 573         switch (type) {
 574         /* ssh1 */
 575         case SSH_AGENTC_RSA_CHALLENGE:
 576                 process_authentication_challenge1(e);
 577                 break;
 578         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 579                 process_request_identities(e, 1);
 580                 break;
 581         case SSH_AGENTC_ADD_RSA_IDENTITY:
 582                 process_add_identity(e, 1);
 583                 break;
 584         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 585                 process_remove_identity(e, 1);
 586                 break;
 587         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 588                 process_remove_all_identities(e, 1);
 589                 break;
 590         /* ssh2 */
 591         case SSH2_AGENTC_SIGN_REQUEST:
 592                 process_sign_request2(e);
 593                 break;
 594         case SSH2_AGENTC_REQUEST_IDENTITIES:
 595                 process_request_identities(e, 2);
 596                 break;
 597         case SSH2_AGENTC_ADD_IDENTITY:
 598                 process_add_identity(e, 2);
 599                 break;
 600         case SSH2_AGENTC_REMOVE_IDENTITY:
 601                 process_remove_identity(e, 2);
 602                 break;
 603         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 604                 process_remove_all_identities(e, 2);
 605                 break;
 606 #ifdef SMARTCARD
 607         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 608                 process_add_smartcard_key(e);
 609                 break;
 610         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 611                 process_remove_smartcard_key(e);
 612                 break;
 613 #endif /* SMARTCARD */
 614         default:
 615                 /* Unknown message.  Respond with failure. */
 616                 error("Unknown message %d", type);
 617                 buffer_clear(&e->input);
 618                 buffer_put_int(&e->output, 1);
 619                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 620                 break;
 621         }
 622 }
 623
 624 static void
 625 new_socket(sock_type type, int fd)
 626 {
 627         u_int i, old_alloc;
 628         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 629                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 630
 631         if (fd > max_fd)
 632                 max_fd = fd;
 633
 634         for (i = 0; i < sockets_alloc; i++)
 635                 if (sockets[i].type == AUTH_UNUSED) {
 636                         sockets[i].fd = fd;
 637                         sockets[i].type = type;
 638                         buffer_init(&sockets[i].input);
 639                         buffer_init(&sockets[i].output);
 640                         return;
 641                 }
 642         old_alloc = sockets_alloc;
 643         sockets_alloc += 10;
 644         if (sockets)
 645                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 646         else
 647                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 648         for (i = old_alloc; i < sockets_alloc; i++)
 649                 sockets[i].type = AUTH_UNUSED;
 650         sockets[old_alloc].type = type;
 651         sockets[old_alloc].fd = fd;
 652         buffer_init(&sockets[old_alloc].input);
 653         buffer_init(&sockets[old_alloc].output);
 654 }
 655
 656 static int
 657 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 658 {
 659         u_int i, sz;
 660         int n = 0;
 661
 662         for (i = 0; i < sockets_alloc; i++) {
 663                 switch (sockets[i].type) {
 664                 case AUTH_SOCKET:
 665                 case AUTH_CONNECTION:
 666                         n = MAX(n, sockets[i].fd);
 667                         break;
 668                 case AUTH_UNUSED:
 669                         break;
 670                 default:
 671                         fatal("Unknown socket type %d", sockets[i].type);
 672                         break;
 673                 }
 674         }
 675
 676         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 677         if (*fdrp == NULL || sz > *nallocp) {
 678                 if (*fdrp)
 679                         xfree(*fdrp);
 680                 if (*fdwp)
 681                         xfree(*fdwp);
 682                 *fdrp = xmalloc(sz);
 683                 *fdwp = xmalloc(sz);
 684                 *nallocp = sz;
 685         }
 686         if (n < *fdl)
 687                 debug("XXX shrink: %d < %d", n, *fdl);
 688         *fdl = n;
 689         memset(*fdrp, 0, sz);
 690         memset(*fdwp, 0, sz);
 691
 692         for (i = 0; i < sockets_alloc; i++) {
 693                 switch (sockets[i].type) {
 694                 case AUTH_SOCKET:
 695                 case AUTH_CONNECTION:
 696                         FD_SET(sockets[i].fd, *fdrp);
 697                         if (buffer_len(&sockets[i].output) > 0)
 698                                 FD_SET(sockets[i].fd, *fdwp);
 699                         break;
 700                 default:
 701                         break;
 702                 }
 703         }
 704         return (1);
 705 }
 706
 707 static void
 708 after_select(fd_set *readset, fd_set *writeset)
 709 {
 710         u_int i;
 711         int len, sock;
 712         socklen_t slen;
 713         char buf[1024];
 714         struct sockaddr_un sunaddr;
 715
 716         for (i = 0; i < sockets_alloc; i++)
 717                 switch (sockets[i].type) {
 718                 case AUTH_UNUSED:
 719                         break;
 720                 case AUTH_SOCKET:
 721                         if (FD_ISSET(sockets[i].fd, readset)) {
 722                                 slen = sizeof(sunaddr);
 723                                 sock = accept(sockets[i].fd,
 724                                     (struct sockaddr *) &sunaddr, &slen);
 725                                 if (sock < 0) {
 726                                         error("accept from AUTH_SOCKET: %s",
 727                                             strerror(errno));
 728                                         break;
 729                                 }
 730                                 new_socket(AUTH_CONNECTION, sock);
 731                         }
 732                         break;
 733                 case AUTH_CONNECTION:
 734                         if (buffer_len(&sockets[i].output) > 0 &&
 735                             FD_ISSET(sockets[i].fd, writeset)) {
 736                                 do {
 737                                         len = write(sockets[i].fd,
 738                                             buffer_ptr(&sockets[i].output),
 739                                             buffer_len(&sockets[i].output));
 740                                         if (len == -1 && (errno == EAGAIN ||
 741                                             errno == EINTR))
 742                                                 continue;
 743                                         break;
 744                                 } while (1);
 745                                 if (len <= 0) {
 746                                         shutdown(sockets[i].fd, SHUT_RDWR);
 747                                         close(sockets[i].fd);
 748                                         sockets[i].type = AUTH_UNUSED;
 749                                         buffer_free(&sockets[i].input);
 750                                         buffer_free(&sockets[i].output);
 751                                         break;
 752                                 }
 753                                 buffer_consume(&sockets[i].output, len);
 754                         }
 755                         if (FD_ISSET(sockets[i].fd, readset)) {
 756                                 do {
 757                                         len = read(sockets[i].fd, buf, sizeof(buf));
 758                                         if (len == -1 && (errno == EAGAIN ||
 759                                             errno == EINTR))
 760                                                 continue;
 761                                         break;
 762                                 } while (1);
 763                                 if (len <= 0) {
 764                                         shutdown(sockets[i].fd, SHUT_RDWR);
 765                                         close(sockets[i].fd);
 766                                         sockets[i].type = AUTH_UNUSED;
 767                                         buffer_free(&sockets[i].input);
 768                                         buffer_free(&sockets[i].output);
 769                                         break;
 770                                 }
 771                                 buffer_append(&sockets[i].input, buf, len);
 772                                 process_message(&sockets[i]);
 773                         }
 774                         break;
 775                 default:
 776                         fatal("Unknown type %d", sockets[i].type);
 777                 }
 778 }
 779
 780 static void
 781 cleanup_socket(void *p)
 782 {
 783         if (socket_name[0])
 784                 unlink(socket_name);
 785         if (socket_dir[0])
 786                 rmdir(socket_dir);
 787 }
 788
 789 static void
 790 cleanup_exit(int i)
 791 {
 792         cleanup_socket(NULL);
 793         exit(i);
 794 }
 795
 796 static void
 797 cleanup_handler(int sig)
 798 {
 799         cleanup_socket(NULL);
 800         _exit(2);
 801 }
 802
 803 static void
 804 check_parent_exists(int sig)
 805 {
 806         int save_errno = errno;
 807
 808         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 809                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 810                 cleanup_handler(sig); /* safe */
 811         }
 812         signal(SIGALRM, check_parent_exists);
 813         alarm(10);
 814         errno = save_errno;
 815 }
 816
 817 static void
 818 usage(void)
 819 {
 820         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 821             __progname);
 822         fprintf(stderr, "Options:\n");
 823         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 824         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 825         fprintf(stderr, "  -k          Kill the current agent.\n");
 826         fprintf(stderr, "  -d          Debug mode.\n");
 827         exit(1);
 828 }
 829
 830 int
 831 main(int ac, char **av)
 832 {
 833         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 834         struct sockaddr_un sunaddr;
 835 #ifdef HAVE_SETRLIMIT
 836         struct rlimit rlim;
 837 #endif
 838 #ifdef HAVE_CYGWIN
 839         int prev_mask;
 840 #endif
 841         pid_t pid;
 842         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 843         extern int optind;
 844         fd_set *readsetp = NULL, *writesetp = NULL;
 845
 846         SSLeay_add_all_algorithms();
 847
 848         __progname = get_progname(av[0]);
 849         init_rng();
 850         seed_rng();
 851
 852 #ifdef __GNU_LIBRARY__
 853         while ((ch = getopt(ac, av, "+cdks")) != -1) {
 854 #else /* __GNU_LIBRARY__ */
 855         while ((ch = getopt(ac, av, "cdks")) != -1) {
 856 #endif /* __GNU_LIBRARY__ */
 857                 switch (ch) {
 858                 case 'c':
 859                         if (s_flag)
 860                                 usage();
 861                         c_flag++;
 862                         break;
 863                 case 'k':
 864                         k_flag++;
 865                         break;
 866                 case 's':
 867                         if (c_flag)
 868                                 usage();
 869                         s_flag++;
 870                         break;
 871                 case 'd':
 872                         if (d_flag)
 873                                 usage();
 874                         d_flag++;
 875                         break;
 876                 default:
 877                         usage();
 878                 }
 879         }
 880         ac -= optind;
 881         av += optind;
 882
 883         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
 884                 usage();
 885
 886         if (ac == 0 && !c_flag && !k_flag && !s_flag && !d_flag) {
 887                 shell = getenv("SHELL");
 888                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 889                         c_flag = 1;
 890         }
 891         if (k_flag) {
 892                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 893                 if (pidstr == NULL) {
 894                         fprintf(stderr, "%s not set, cannot kill agent\n",
 895                             SSH_AGENTPID_ENV_NAME);
 896                         exit(1);
 897                 }
 898                 pid = atoi(pidstr);
 899                 if (pid < 1) {
 900                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 901                             SSH_AGENTPID_ENV_NAME, pidstr);
 902                         exit(1);
 903                 }
 904                 if (kill(pid, SIGTERM) == -1) {
 905                         perror("kill");
 906                         exit(1);
 907                 }
 908                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 909                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 910                 printf(format, SSH_AGENTPID_ENV_NAME);
 911                 printf("echo Agent pid %d killed;\n", pid);
 912                 exit(0);
 913         }
 914         parent_pid = getpid();
 915
 916         /* Create private directory for agent socket */
 917         strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 918         if (mkdtemp(socket_dir) == NULL) {
 919                 perror("mkdtemp: private socket dir");
 920                 exit(1);
 921         }
 922         snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 923             parent_pid);
 924
 925         /*
 926          * Create socket early so it will exist before command gets run from
 927          * the parent.
 928          */
 929         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 930         if (sock < 0) {
 931                 perror("socket");
 932                 cleanup_exit(1);
 933         }
 934         memset(&sunaddr, 0, sizeof(sunaddr));
 935         sunaddr.sun_family = AF_UNIX;
 936         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 937 #ifdef HAVE_CYGWIN
 938         prev_mask = umask(0177);
 939 #endif
 940         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 941                 perror("bind");
 942 #ifdef HAVE_CYGWIN
 943                 umask(prev_mask);
 944 #endif
 945                 cleanup_exit(1);
 946         }
 947 #ifdef HAVE_CYGWIN
 948         umask(prev_mask);
 949 #endif
 950         if (listen(sock, 5) < 0) {
 951                 perror("listen");
 952                 cleanup_exit(1);
 953         }
 954
 955         /*
 956          * Fork, and have the parent execute the command, if any, or present
 957          * the socket data.  The child continues as the authentication agent.
 958          */
 959         if (d_flag) {
 960                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
 961                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 962                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 963                     SSH_AUTHSOCKET_ENV_NAME);
 964                 printf("echo Agent pid %d;\n", parent_pid);
 965                 goto skip;
 966         }
 967         pid = fork();
 968         if (pid == -1) {
 969                 perror("fork");
 970                 cleanup_exit(1);
 971         }
 972         if (pid != 0) {         /* Parent - execute the given command. */
 973                 close(sock);
 974                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 975                 if (ac == 0) {
 976                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 977                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 978                             SSH_AUTHSOCKET_ENV_NAME);
 979                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 980                             SSH_AGENTPID_ENV_NAME);
 981                         printf("echo Agent pid %d;\n", pid);
 982                         exit(0);
 983                 }
 984                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 985                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 986                         perror("setenv");
 987                         exit(1);
 988                 }
 989                 execvp(av[0], av);
 990                 perror(av[0]);
 991                 exit(1);
 992         }
 993         /* child */
 994         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
 995
 996         if (setsid() == -1) {
 997                 error("setsid: %s", strerror(errno));
 998                 cleanup_exit(1);
 999         }
1000
1001         (void)chdir("/");
1002         close(0);
1003         close(1);
1004         close(2);
1005
1006 #ifdef HAVE_SETRLIMIT
1007         /* deny core dumps, since memory contains unencrypted private keys */
1008         rlim.rlim_cur = rlim.rlim_max = 0;
1009         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1010                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1011                 cleanup_exit(1);
1012         }
1013 #endif
1014
1015 skip:
1016         fatal_add_cleanup(cleanup_socket, NULL);
1017         new_socket(AUTH_SOCKET, sock);
1018         if (ac > 0) {
1019                 signal(SIGALRM, check_parent_exists);
1020                 alarm(10);
1021         }
1022         idtab_init();
1023         if (!d_flag)
1024                 signal(SIGINT, SIG_IGN);
1025         signal(SIGPIPE, SIG_IGN);
1026         signal(SIGHUP, cleanup_handler);
1027         signal(SIGTERM, cleanup_handler);
1028         nalloc = 0;
1029
1030         while (1) {
1031                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1032                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1033                         if (errno == EINTR)
1034                                 continue;
1035                         fatal("select: %s", strerror(errno));
1036                 }
1037                 after_select(readsetp, writesetp);
1038         }
1039         /* NOTREACHED */
1040 }