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 1.82 2002/03/04 17:27:39 stevesk 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;
 458         int success = 0;
 459
 460         sc_reader_id = buffer_get_string(&e->input, NULL);
 461         k = sc_get_key(sc_reader_id);
 462         xfree(sc_reader_id);
 463
 464         if (k == NULL) {
 465                 error("sc_get_pubkey failed");
 466                 goto send;
 467         }
 468         success = 1;
 469
 470         tab = idtab_lookup(1);
 471         k->type = KEY_RSA1;
 472         if (lookup_identity(k, 1) == NULL) {
 473                 Identity *id = xmalloc(sizeof(Identity));
 474                 n = key_new(KEY_RSA1);
 475                 BN_copy(n->rsa->n, k->rsa->n);
 476                 BN_copy(n->rsa->e, k->rsa->e);
 477                 RSA_set_method(n->rsa, sc_get_engine());
 478                 id->key = n;
 479                 id->comment = xstrdup("rsa1 smartcard");
 480                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 481                 tab->nentries++;
 482         }
 483         k->type = KEY_RSA;
 484         tab = idtab_lookup(2);
 485         if (lookup_identity(k, 2) == NULL) {
 486                 Identity *id = xmalloc(sizeof(Identity));
 487                 n = key_new(KEY_RSA);
 488                 BN_copy(n->rsa->n, k->rsa->n);
 489                 BN_copy(n->rsa->e, k->rsa->e);
 490                 RSA_set_method(n->rsa, sc_get_engine());
 491                 id->key = n;
 492                 id->comment = xstrdup("rsa smartcard");
 493                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 494                 tab->nentries++;
 495         }
 496         key_free(k);
 497 send:
 498         buffer_put_int(&e->output, 1);
 499         buffer_put_char(&e->output,
 500             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 501 }
 502
 503 static void
 504 process_remove_smartcard_key(SocketEntry *e)
 505 {
 506         Key *k = NULL;
 507         int success = 0;
 508         char *sc_reader_id = NULL;
 509
 510         sc_reader_id = buffer_get_string(&e->input, NULL);
 511         k = sc_get_key(sc_reader_id);
 512         xfree(sc_reader_id);
 513
 514         if (k == NULL) {
 515                 error("sc_get_pubkey failed");
 516         } else {
 517                 Identity *id;
 518                 k->type = KEY_RSA1;
 519                 id = lookup_identity(k, 1);
 520                 if (id != NULL) {
 521                         Idtab *tab = idtab_lookup(1);
 522                         TAILQ_REMOVE(&tab->idlist, id, next);
 523                         free_identity(id);
 524                         tab->nentries--;
 525                         success = 1;
 526                 }
 527                 k->type = KEY_RSA;
 528                 id = lookup_identity(k, 2);
 529                 if (id != NULL) {
 530                         Idtab *tab = idtab_lookup(2);
 531                         TAILQ_REMOVE(&tab->idlist, id, next);
 532                         free_identity(id);
 533                         tab->nentries--;
 534                         success = 1;
 535                 }
 536                 key_free(k);
 537         }
 538
 539         buffer_put_int(&e->output, 1);
 540         buffer_put_char(&e->output,
 541             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 542 }
 543 #endif /* SMARTCARD */
 544
 545 /* dispatch incoming messages */
 546
 547 static void
 548 process_message(SocketEntry *e)
 549 {
 550         u_int msg_len;
 551         u_int type;
 552         u_char *cp;
 553         if (buffer_len(&e->input) < 5)
 554                 return;         /* Incomplete message. */
 555         cp = buffer_ptr(&e->input);
 556         msg_len = GET_32BIT(cp);
 557         if (msg_len > 256 * 1024) {
 558                 shutdown(e->fd, SHUT_RDWR);
 559                 close(e->fd);
 560                 e->type = AUTH_UNUSED;
 561                 return;
 562         }
 563         if (buffer_len(&e->input) < msg_len + 4)
 564                 return;
 565         buffer_consume(&e->input, 4);
 566         type = buffer_get_char(&e->input);
 567
 568         debug("type %d", type);
 569         switch (type) {
 570         /* ssh1 */
 571         case SSH_AGENTC_RSA_CHALLENGE:
 572                 process_authentication_challenge1(e);
 573                 break;
 574         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 575                 process_request_identities(e, 1);
 576                 break;
 577         case SSH_AGENTC_ADD_RSA_IDENTITY:
 578                 process_add_identity(e, 1);
 579                 break;
 580         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 581                 process_remove_identity(e, 1);
 582                 break;
 583         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 584                 process_remove_all_identities(e, 1);
 585                 break;
 586         /* ssh2 */
 587         case SSH2_AGENTC_SIGN_REQUEST:
 588                 process_sign_request2(e);
 589                 break;
 590         case SSH2_AGENTC_REQUEST_IDENTITIES:
 591                 process_request_identities(e, 2);
 592                 break;
 593         case SSH2_AGENTC_ADD_IDENTITY:
 594                 process_add_identity(e, 2);
 595                 break;
 596         case SSH2_AGENTC_REMOVE_IDENTITY:
 597                 process_remove_identity(e, 2);
 598                 break;
 599         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 600                 process_remove_all_identities(e, 2);
 601                 break;
 602 #ifdef SMARTCARD
 603         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 604                 process_add_smartcard_key(e);
 605                 break;
 606         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 607                 process_remove_smartcard_key(e);
 608                 break;
 609 #endif /* SMARTCARD */
 610         default:
 611                 /* Unknown message.  Respond with failure. */
 612                 error("Unknown message %d", type);
 613                 buffer_clear(&e->input);
 614                 buffer_put_int(&e->output, 1);
 615                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 616                 break;
 617         }
 618 }
 619
 620 static void
 621 new_socket(sock_type type, int fd)
 622 {
 623         u_int i, old_alloc;
 624         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 625                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 626
 627         if (fd > max_fd)
 628                 max_fd = fd;
 629
 630         for (i = 0; i < sockets_alloc; i++)
 631                 if (sockets[i].type == AUTH_UNUSED) {
 632                         sockets[i].fd = fd;
 633                         sockets[i].type = type;
 634                         buffer_init(&sockets[i].input);
 635                         buffer_init(&sockets[i].output);
 636                         return;
 637                 }
 638         old_alloc = sockets_alloc;
 639         sockets_alloc += 10;
 640         if (sockets)
 641                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 642         else
 643                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 644         for (i = old_alloc; i < sockets_alloc; i++)
 645                 sockets[i].type = AUTH_UNUSED;
 646         sockets[old_alloc].type = type;
 647         sockets[old_alloc].fd = fd;
 648         buffer_init(&sockets[old_alloc].input);
 649         buffer_init(&sockets[old_alloc].output);
 650 }
 651
 652 static int
 653 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 654 {
 655         u_int i, sz;
 656         int n = 0;
 657
 658         for (i = 0; i < sockets_alloc; i++) {
 659                 switch (sockets[i].type) {
 660                 case AUTH_SOCKET:
 661                 case AUTH_CONNECTION:
 662                         n = MAX(n, sockets[i].fd);
 663                         break;
 664                 case AUTH_UNUSED:
 665                         break;
 666                 default:
 667                         fatal("Unknown socket type %d", sockets[i].type);
 668                         break;
 669                 }
 670         }
 671
 672         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 673         if (*fdrp == NULL || sz > *nallocp) {
 674                 if (*fdrp)
 675                         xfree(*fdrp);
 676                 if (*fdwp)
 677                         xfree(*fdwp);
 678                 *fdrp = xmalloc(sz);
 679                 *fdwp = xmalloc(sz);
 680                 *nallocp = sz;
 681         }
 682         if (n < *fdl)
 683                 debug("XXX shrink: %d < %d", n, *fdl);
 684         *fdl = n;
 685         memset(*fdrp, 0, sz);
 686         memset(*fdwp, 0, sz);
 687
 688         for (i = 0; i < sockets_alloc; i++) {
 689                 switch (sockets[i].type) {
 690                 case AUTH_SOCKET:
 691                 case AUTH_CONNECTION:
 692                         FD_SET(sockets[i].fd, *fdrp);
 693                         if (buffer_len(&sockets[i].output) > 0)
 694                                 FD_SET(sockets[i].fd, *fdwp);
 695                         break;
 696                 default:
 697                         break;
 698                 }
 699         }
 700         return (1);
 701 }
 702
 703 static void
 704 after_select(fd_set *readset, fd_set *writeset)
 705 {
 706         u_int i;
 707         int len, sock;
 708         socklen_t slen;
 709         char buf[1024];
 710         struct sockaddr_un sunaddr;
 711
 712         for (i = 0; i < sockets_alloc; i++)
 713                 switch (sockets[i].type) {
 714                 case AUTH_UNUSED:
 715                         break;
 716                 case AUTH_SOCKET:
 717                         if (FD_ISSET(sockets[i].fd, readset)) {
 718                                 slen = sizeof(sunaddr);
 719                                 sock = accept(sockets[i].fd,
 720                                     (struct sockaddr *) &sunaddr, &slen);
 721                                 if (sock < 0) {
 722                                         error("accept from AUTH_SOCKET: %s",
 723                                             strerror(errno));
 724                                         break;
 725                                 }
 726                                 new_socket(AUTH_CONNECTION, sock);
 727                         }
 728                         break;
 729                 case AUTH_CONNECTION:
 730                         if (buffer_len(&sockets[i].output) > 0 &&
 731                             FD_ISSET(sockets[i].fd, writeset)) {
 732                                 do {
 733                                         len = write(sockets[i].fd,
 734                                             buffer_ptr(&sockets[i].output),
 735                                             buffer_len(&sockets[i].output));
 736                                         if (len == -1 && (errno == EAGAIN ||
 737                                             errno == EINTR))
 738                                                 continue;
 739                                         break;
 740                                 } while (1);
 741                                 if (len <= 0) {
 742                                         shutdown(sockets[i].fd, SHUT_RDWR);
 743                                         close(sockets[i].fd);
 744                                         sockets[i].type = AUTH_UNUSED;
 745                                         buffer_free(&sockets[i].input);
 746                                         buffer_free(&sockets[i].output);
 747                                         break;
 748                                 }
 749                                 buffer_consume(&sockets[i].output, len);
 750                         }
 751                         if (FD_ISSET(sockets[i].fd, readset)) {
 752                                 do {
 753                                         len = read(sockets[i].fd, buf, sizeof(buf));
 754                                         if (len == -1 && (errno == EAGAIN ||
 755                                             errno == EINTR))
 756                                                 continue;
 757                                         break;
 758                                 } while (1);
 759                                 if (len <= 0) {
 760                                         shutdown(sockets[i].fd, SHUT_RDWR);
 761                                         close(sockets[i].fd);
 762                                         sockets[i].type = AUTH_UNUSED;
 763                                         buffer_free(&sockets[i].input);
 764                                         buffer_free(&sockets[i].output);
 765                                         break;
 766                                 }
 767                                 buffer_append(&sockets[i].input, buf, len);
 768                                 process_message(&sockets[i]);
 769                         }
 770                         break;
 771                 default:
 772                         fatal("Unknown type %d", sockets[i].type);
 773                 }
 774 }
 775
 776 static void
 777 cleanup_socket(void *p)
 778 {
 779         if (socket_name[0])
 780                 unlink(socket_name);
 781         if (socket_dir[0])
 782                 rmdir(socket_dir);
 783 }
 784
 785 static void
 786 cleanup_exit(int i)
 787 {
 788         cleanup_socket(NULL);
 789         exit(i);
 790 }
 791
 792 static void
 793 cleanup_handler(int sig)
 794 {
 795         cleanup_socket(NULL);
 796         _exit(2);
 797 }
 798
 799 static void
 800 check_parent_exists(int sig)
 801 {
 802         int save_errno = errno;
 803
 804         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 805                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 806                 cleanup_handler(sig); /* safe */
 807         }
 808         signal(SIGALRM, check_parent_exists);
 809         alarm(10);
 810         errno = save_errno;
 811 }
 812
 813 static void
 814 usage(void)
 815 {
 816         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 817             __progname);
 818         fprintf(stderr, "Options:\n");
 819         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 820         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 821         fprintf(stderr, "  -k          Kill the current agent.\n");
 822         fprintf(stderr, "  -d          Debug mode.\n");
 823         exit(1);
 824 }
 825
 826 int
 827 main(int ac, char **av)
 828 {
 829         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 830         struct sockaddr_un sunaddr;
 831 #ifdef HAVE_SETRLIMIT
 832         struct rlimit rlim;
 833 #endif
 834 #ifdef HAVE_CYGWIN
 835         int prev_mask;
 836 #endif
 837         pid_t pid;
 838         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 839         extern int optind;
 840         fd_set *readsetp = NULL, *writesetp = NULL;
 841
 842         SSLeay_add_all_algorithms();
 843
 844         __progname = get_progname(av[0]);
 845         init_rng();
 846         seed_rng();
 847
 848 #ifdef __GNU_LIBRARY__
 849         while ((ch = getopt(ac, av, "+cdks")) != -1) {
 850 #else /* __GNU_LIBRARY__ */
 851         while ((ch = getopt(ac, av, "cdks")) != -1) {
 852 #endif /* __GNU_LIBRARY__ */
 853                 switch (ch) {
 854                 case 'c':
 855                         if (s_flag)
 856                                 usage();
 857                         c_flag++;
 858                         break;
 859                 case 'k':
 860                         k_flag++;
 861                         break;
 862                 case 's':
 863                         if (c_flag)
 864                                 usage();
 865                         s_flag++;
 866                         break;
 867                 case 'd':
 868                         if (d_flag)
 869                                 usage();
 870                         d_flag++;
 871                         break;
 872                 default:
 873                         usage();
 874                 }
 875         }
 876         ac -= optind;
 877         av += optind;
 878
 879         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
 880                 usage();
 881
 882         if (ac == 0 && !c_flag && !k_flag && !s_flag && !d_flag) {
 883                 shell = getenv("SHELL");
 884                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 885                         c_flag = 1;
 886         }
 887         if (k_flag) {
 888                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 889                 if (pidstr == NULL) {
 890                         fprintf(stderr, "%s not set, cannot kill agent\n",
 891                             SSH_AGENTPID_ENV_NAME);
 892                         exit(1);
 893                 }
 894                 pid = atoi(pidstr);
 895                 if (pid < 1) {
 896                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 897                             SSH_AGENTPID_ENV_NAME, pidstr);
 898                         exit(1);
 899                 }
 900                 if (kill(pid, SIGTERM) == -1) {
 901                         perror("kill");
 902                         exit(1);
 903                 }
 904                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 905                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 906                 printf(format, SSH_AGENTPID_ENV_NAME);
 907                 printf("echo Agent pid %d killed;\n", pid);
 908                 exit(0);
 909         }
 910         parent_pid = getpid();
 911
 912         /* Create private directory for agent socket */
 913         strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 914         if (mkdtemp(socket_dir) == NULL) {
 915                 perror("mkdtemp: private socket dir");
 916                 exit(1);
 917         }
 918         snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 919             parent_pid);
 920
 921         /*
 922          * Create socket early so it will exist before command gets run from
 923          * the parent.
 924          */
 925         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 926         if (sock < 0) {
 927                 perror("socket");
 928                 cleanup_exit(1);
 929         }
 930         memset(&sunaddr, 0, sizeof(sunaddr));
 931         sunaddr.sun_family = AF_UNIX;
 932         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 933 #ifdef HAVE_CYGWIN
 934         prev_mask = umask(0177);
 935 #endif
 936         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 937                 perror("bind");
 938 #ifdef HAVE_CYGWIN
 939                 umask(prev_mask);
 940 #endif
 941                 cleanup_exit(1);
 942         }
 943 #ifdef HAVE_CYGWIN
 944         umask(prev_mask);
 945 #endif
 946         if (listen(sock, 5) < 0) {
 947                 perror("listen");
 948                 cleanup_exit(1);
 949         }
 950
 951         /*
 952          * Fork, and have the parent execute the command, if any, or present
 953          * the socket data.  The child continues as the authentication agent.
 954          */
 955         if (d_flag) {
 956                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
 957                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 958                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 959                     SSH_AUTHSOCKET_ENV_NAME);
 960                 printf("echo Agent pid %d;\n", parent_pid);
 961                 goto skip;
 962         }
 963         pid = fork();
 964         if (pid == -1) {
 965                 perror("fork");
 966                 cleanup_exit(1);
 967         }
 968         if (pid != 0) {         /* Parent - execute the given command. */
 969                 close(sock);
 970                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 971                 if (ac == 0) {
 972                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 973                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 974                             SSH_AUTHSOCKET_ENV_NAME);
 975                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 976                             SSH_AGENTPID_ENV_NAME);
 977                         printf("echo Agent pid %d;\n", pid);
 978                         exit(0);
 979                 }
 980                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 981                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 982                         perror("setenv");
 983                         exit(1);
 984                 }
 985                 execvp(av[0], av);
 986                 perror(av[0]);
 987                 exit(1);
 988         }
 989         /* child */
 990         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
 991
 992         if (setsid() == -1) {
 993                 error("setsid: %s", strerror(errno));
 994                 cleanup_exit(1);
 995         }
 996
 997         (void)chdir("/");
 998         close(0);
 999         close(1);
1000         close(2);
1001
1002 #ifdef HAVE_SETRLIMIT
1003         /* deny core dumps, since memory contains unencrypted private keys */
1004         rlim.rlim_cur = rlim.rlim_max = 0;
1005         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1006                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1007                 cleanup_exit(1);
1008         }
1009 #endif
1010
1011 skip:
1012         fatal_add_cleanup(cleanup_socket, NULL);
1013         new_socket(AUTH_SOCKET, sock);
1014         if (ac > 0) {
1015                 signal(SIGALRM, check_parent_exists);
1016                 alarm(10);
1017         }
1018         idtab_init();
1019         if (!d_flag)
1020                 signal(SIGINT, SIG_IGN);
1021         signal(SIGPIPE, SIG_IGN);
1022         signal(SIGHUP, cleanup_handler);
1023         signal(SIGTERM, cleanup_handler);
1024         nalloc = 0;
1025
1026         while (1) {
1027                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1028                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1029                         if (errno == EINTR)
1030                                 continue;
1031                         fatal("select: %s", strerror(errno));
1032                 }
1033                 after_select(readsetp, writesetp);
1034         }
1035         /* NOTREACHED */
1036 }