ssh-agent.c

   1 /*      $OpenBSD: ssh-agent.c,v 1.80 2002/02/04 00:53:39 stevesk 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 1.80 2002/02/04 00:53:39 stevesk Exp $");
  40
  41 #if defined(HAVE_SYS_QUEUE_H) && !defined(HAVE_BOGUS_SYS_QUEUE_H)
  42 #include <sys/queue.h>
  43 #else
  44 #include "openbsd-compat/fake-queue.h"
  45 #endif
  46
  47
  48 #include <openssl/evp.h>
  49 #include <openssl/md5.h>
  50
  51 #include "ssh.h"
  52 #include "rsa.h"
  53 #include "buffer.h"
  54 #include "bufaux.h"
  55 #include "xmalloc.h"
  56 #include "getput.h"
  57 #include "key.h"
  58 #include "authfd.h"
  59 #include "compat.h"
  60 #include "log.h"
  61
  62 #ifdef SMARTCARD
  63 #include <openssl/engine.h>
  64 #include "scard.h"
  65 #endif
  66
  67 typedef enum {
  68         AUTH_UNUSED,
  69         AUTH_SOCKET,
  70         AUTH_CONNECTION
  71 } sock_type;
  72
  73 typedef struct {
  74         int fd;
  75         sock_type type;
  76         Buffer input;
  77         Buffer output;
  78 } SocketEntry;
  79
  80 u_int sockets_alloc = 0;
  81 SocketEntry *sockets = NULL;
  82
  83 typedef struct identity {
  84         TAILQ_ENTRY(identity) next;
  85         Key *key;
  86         char *comment;
  87 } Identity;
  88
  89 typedef struct {
  90         int nentries;
  91         TAILQ_HEAD(idqueue, identity) idlist;
  92 } Idtab;
  93
  94 /* private key table, one per protocol version */
  95 Idtab idtable[3];
  96
  97 int max_fd = 0;
  98
  99 /* pid of shell == parent of agent */
 100 pid_t parent_pid = -1;
 101
 102 /* pathname and directory for AUTH_SOCKET */
 103 char socket_name[1024];
 104 char socket_dir[1024];
 105
 106 #ifdef HAVE___PROGNAME
 107 extern char *__progname;
 108 #else
 109 char *__progname;
 110 #endif
 111
 112 static void
 113 idtab_init(void)
 114 {
 115         int i;
 116         for (i = 0; i <=2; i++) {
 117                 TAILQ_INIT(&idtable[i].idlist);
 118                 idtable[i].nentries = 0;
 119         }
 120 }
 121
 122 /* return private key table for requested protocol version */
 123 static Idtab *
 124 idtab_lookup(int version)
 125 {
 126         if (version < 1 || version > 2)
 127                 fatal("internal error, bad protocol version %d", version);
 128         return &idtable[version];
 129 }
 130
 131 /* return matching private key for given public key */
 132 static Identity *
 133 lookup_identity(Key *key, int version)
 134 {
 135         Identity *id;
 136
 137         Idtab *tab = idtab_lookup(version);
 138         TAILQ_FOREACH(id, &tab->idlist, next) {
 139                 if (key_equal(key, id->key))
 140                         return (id);
 141         }
 142         return (NULL);
 143 }
 144
 145 static void
 146 free_identity(Identity *id)
 147 {
 148         key_free(id->key);
 149         xfree(id->comment);
 150         xfree(id);
 151 }
 152
 153 /* send list of supported public keys to 'client' */
 154 static void
 155 process_request_identities(SocketEntry *e, int version)
 156 {
 157         Idtab *tab = idtab_lookup(version);
 158         Buffer msg;
 159         Identity *id;
 160
 161         buffer_init(&msg);
 162         buffer_put_char(&msg, (version == 1) ?
 163             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 164         buffer_put_int(&msg, tab->nentries);
 165         TAILQ_FOREACH(id, &tab->idlist, next) {
 166                 if (id->key->type == KEY_RSA1) {
 167                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 168                         buffer_put_bignum(&msg, id->key->rsa->e);
 169                         buffer_put_bignum(&msg, id->key->rsa->n);
 170                 } else {
 171                         u_char *blob;
 172                         u_int blen;
 173                         key_to_blob(id->key, &blob, &blen);
 174                         buffer_put_string(&msg, blob, blen);
 175                         xfree(blob);
 176                 }
 177                 buffer_put_cstring(&msg, id->comment);
 178         }
 179         buffer_put_int(&e->output, buffer_len(&msg));
 180         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 181         buffer_free(&msg);
 182 }
 183
 184 /* ssh1 only */
 185 static void
 186 process_authentication_challenge1(SocketEntry *e)
 187 {
 188         Identity *id;
 189         Key *key;
 190         BIGNUM *challenge;
 191         int i, len;
 192         Buffer msg;
 193         MD5_CTX md;
 194         u_char buf[32], mdbuf[16], session_id[16];
 195         u_int response_type;
 196
 197         buffer_init(&msg);
 198         key = key_new(KEY_RSA1);
 199         if ((challenge = BN_new()) == NULL)
 200                 fatal("process_authentication_challenge1: BN_new failed");
 201
 202         buffer_get_int(&e->input);                              /* ignored */
 203         buffer_get_bignum(&e->input, key->rsa->e);
 204         buffer_get_bignum(&e->input, key->rsa->n);
 205         buffer_get_bignum(&e->input, challenge);
 206
 207         /* Only protocol 1.1 is supported */
 208         if (buffer_len(&e->input) == 0)
 209                 goto failure;
 210         buffer_get(&e->input, session_id, 16);
 211         response_type = buffer_get_int(&e->input);
 212         if (response_type != 1)
 213                 goto failure;
 214
 215         id = lookup_identity(key, 1);
 216         if (id != NULL) {
 217                 Key *private = id->key;
 218                 /* Decrypt the challenge using the private key. */
 219                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 220                         goto failure;
 221
 222                 /* The response is MD5 of decrypted challenge plus session id. */
 223                 len = BN_num_bytes(challenge);
 224                 if (len <= 0 || len > 32) {
 225                         log("process_authentication_challenge: bad challenge length %d", len);
 226                         goto failure;
 227                 }
 228                 memset(buf, 0, 32);
 229                 BN_bn2bin(challenge, buf + 32 - len);
 230                 MD5_Init(&md);
 231                 MD5_Update(&md, buf, 32);
 232                 MD5_Update(&md, session_id, 16);
 233                 MD5_Final(mdbuf, &md);
 234
 235                 /* Send the response. */
 236                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 237                 for (i = 0; i < 16; i++)
 238                         buffer_put_char(&msg, mdbuf[i]);
 239                 goto send;
 240         }
 241
 242 failure:
 243         /* Unknown identity or protocol error.  Send failure. */
 244         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 245 send:
 246         buffer_put_int(&e->output, buffer_len(&msg));
 247         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 248         key_free(key);
 249         BN_clear_free(challenge);
 250         buffer_free(&msg);
 251 }
 252
 253 /* ssh2 only */
 254 static void
 255 process_sign_request2(SocketEntry *e)
 256 {
 257         extern int datafellows;
 258         Key *key;
 259         u_char *blob, *data, *signature = NULL;
 260         u_int blen, dlen, slen = 0;
 261         int flags;
 262         Buffer msg;
 263         int ok = -1;
 264
 265         datafellows = 0;
 266
 267         blob = buffer_get_string(&e->input, &blen);
 268         data = buffer_get_string(&e->input, &dlen);
 269
 270         flags = buffer_get_int(&e->input);
 271         if (flags & SSH_AGENT_OLD_SIGNATURE)
 272                 datafellows = SSH_BUG_SIGBLOB;
 273
 274         key = key_from_blob(blob, blen);
 275         if (key != NULL) {
 276                 Identity *id = lookup_identity(key, 2);
 277                 if (id != NULL)
 278                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 279         }
 280         key_free(key);
 281         buffer_init(&msg);
 282         if (ok == 0) {
 283                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 284                 buffer_put_string(&msg, signature, slen);
 285         } else {
 286                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 287         }
 288         buffer_put_int(&e->output, buffer_len(&msg));
 289         buffer_append(&e->output, buffer_ptr(&msg),
 290             buffer_len(&msg));
 291         buffer_free(&msg);
 292         xfree(data);
 293         xfree(blob);
 294         if (signature != NULL)
 295                 xfree(signature);
 296 }
 297
 298 /* shared */
 299 static void
 300 process_remove_identity(SocketEntry *e, int version)
 301 {
 302         Key *key = NULL;
 303         u_char *blob;
 304         u_int blen;
 305         u_int bits;
 306         int success = 0;
 307
 308         switch (version) {
 309         case 1:
 310                 key = key_new(KEY_RSA1);
 311                 bits = buffer_get_int(&e->input);
 312                 buffer_get_bignum(&e->input, key->rsa->e);
 313                 buffer_get_bignum(&e->input, key->rsa->n);
 314
 315                 if (bits != key_size(key))
 316                         log("Warning: identity keysize mismatch: actual %d, announced %d",
 317                             key_size(key), bits);
 318                 break;
 319         case 2:
 320                 blob = buffer_get_string(&e->input, &blen);
 321                 key = key_from_blob(blob, blen);
 322                 xfree(blob);
 323                 break;
 324         }
 325         if (key != NULL) {
 326                 Identity *id = lookup_identity(key, version);
 327                 if (id != NULL) {
 328                         /*
 329                          * We have this key.  Free the old key.  Since we
 330                          * don\'t want to leave empty slots in the middle of
 331                          * the array, we actually free the key there and move
 332                          * all the entries between the empty slot and the end
 333                          * of the array.
 334                          */
 335                         Idtab *tab = idtab_lookup(version);
 336                         if (tab->nentries < 1)
 337                                 fatal("process_remove_identity: "
 338                                     "internal error: tab->nentries %d",
 339                                     tab->nentries);
 340                         TAILQ_REMOVE(&tab->idlist, id, next);
 341                         free_identity(id);
 342                         tab->nentries--;
 343                         success = 1;
 344                 }
 345                 key_free(key);
 346         }
 347         buffer_put_int(&e->output, 1);
 348         buffer_put_char(&e->output,
 349             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 350 }
 351
 352 static void
 353 process_remove_all_identities(SocketEntry *e, int version)
 354 {
 355         Idtab *tab = idtab_lookup(version);
 356         Identity *id;
 357
 358         /* Loop over all identities and clear the keys. */
 359         for (id = TAILQ_FIRST(&tab->idlist); id;
 360             id = TAILQ_FIRST(&tab->idlist)) {
 361                 TAILQ_REMOVE(&tab->idlist, id, next);
 362                 free_identity(id);
 363         }
 364
 365         /* Mark that there are no identities. */
 366         tab->nentries = 0;
 367
 368         /* Send success. */
 369         buffer_put_int(&e->output, 1);
 370         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 371         return;
 372 }
 373
 374 static void
 375 process_add_identity(SocketEntry *e, int version)
 376 {
 377         Key *k = NULL;
 378         char *type_name;
 379         char *comment;
 380         int type, success = 0;
 381         Idtab *tab = idtab_lookup(version);
 382
 383         switch (version) {
 384         case 1:
 385                 k = key_new_private(KEY_RSA1);
 386                 buffer_get_int(&e->input);                      /* ignored */
 387                 buffer_get_bignum(&e->input, k->rsa->n);
 388                 buffer_get_bignum(&e->input, k->rsa->e);
 389                 buffer_get_bignum(&e->input, k->rsa->d);
 390                 buffer_get_bignum(&e->input, k->rsa->iqmp);
 391
 392                 /* SSH and SSL have p and q swapped */
 393                 buffer_get_bignum(&e->input, k->rsa->q);        /* p */
 394                 buffer_get_bignum(&e->input, k->rsa->p);        /* q */
 395
 396                 /* Generate additional parameters */
 397                 rsa_generate_additional_parameters(k->rsa);
 398                 break;
 399         case 2:
 400                 type_name = buffer_get_string(&e->input, NULL);
 401                 type = key_type_from_name(type_name);
 402                 xfree(type_name);
 403                 switch (type) {
 404                 case KEY_DSA:
 405                         k = key_new_private(type);
 406                         buffer_get_bignum2(&e->input, k->dsa->p);
 407                         buffer_get_bignum2(&e->input, k->dsa->q);
 408                         buffer_get_bignum2(&e->input, k->dsa->g);
 409                         buffer_get_bignum2(&e->input, k->dsa->pub_key);
 410                         buffer_get_bignum2(&e->input, k->dsa->priv_key);
 411                         break;
 412                 case KEY_RSA:
 413                         k = key_new_private(type);
 414                         buffer_get_bignum2(&e->input, k->rsa->n);
 415                         buffer_get_bignum2(&e->input, k->rsa->e);
 416                         buffer_get_bignum2(&e->input, k->rsa->d);
 417                         buffer_get_bignum2(&e->input, k->rsa->iqmp);
 418                         buffer_get_bignum2(&e->input, k->rsa->p);
 419                         buffer_get_bignum2(&e->input, k->rsa->q);
 420
 421                         /* Generate additional parameters */
 422                         rsa_generate_additional_parameters(k->rsa);
 423                         break;
 424                 default:
 425                         buffer_clear(&e->input);
 426                         goto send;
 427                 }
 428                 break;
 429         }
 430         comment = buffer_get_string(&e->input, NULL);
 431         if (k == NULL) {
 432                 xfree(comment);
 433                 goto send;
 434         }
 435         success = 1;
 436         if (lookup_identity(k, version) == NULL) {
 437                 Identity *id = xmalloc(sizeof(Identity));
 438                 id->key = k;
 439                 id->comment = comment;
 440                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 441                 /* Increment the number of identities. */
 442                 tab->nentries++;
 443         } else {
 444                 key_free(k);
 445                 xfree(comment);
 446         }
 447 send:
 448         buffer_put_int(&e->output, 1);
 449         buffer_put_char(&e->output,
 450             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 451 }
 452
 453
 454 #ifdef SMARTCARD
 455 static void
 456 process_add_smartcard_key (SocketEntry *e)
 457 {
 458         Idtab *tab;
 459         Key *n = NULL, *k = NULL;
 460         char *sc_reader_id = NULL;
 461         int success = 0;
 462
 463         sc_reader_id = buffer_get_string(&e->input, NULL);
 464         k = sc_get_key(sc_reader_id);
 465         xfree(sc_reader_id);
 466
 467         if (k == NULL) {
 468                 error("sc_get_pubkey failed");
 469                 goto send;
 470         }
 471         success = 1;
 472
 473         tab = idtab_lookup(1);
 474         k->type = KEY_RSA1;
 475         if (lookup_identity(k, 1) == NULL) {
 476                 Identity *id = xmalloc(sizeof(Identity));
 477                 n = key_new(KEY_RSA1);
 478                 BN_copy(n->rsa->n, k->rsa->n);
 479                 BN_copy(n->rsa->e, k->rsa->e);
 480                 RSA_set_method(n->rsa, sc_get_engine());
 481                 id->key = n;
 482                 id->comment = xstrdup("rsa1 smartcard");
 483                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 484                 tab->nentries++;
 485         }
 486         k->type = KEY_RSA;
 487         tab = idtab_lookup(2);
 488         if (lookup_identity(k, 2) == NULL) {
 489                 Identity *id = xmalloc(sizeof(Identity));
 490                 n = key_new(KEY_RSA);
 491                 BN_copy(n->rsa->n, k->rsa->n);
 492                 BN_copy(n->rsa->e, k->rsa->e);
 493                 RSA_set_method(n->rsa, sc_get_engine());
 494                 id->key = n;
 495                 id->comment = xstrdup("rsa smartcard");
 496                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 497                 tab->nentries++;
 498         }
 499         key_free(k);
 500 send:
 501         buffer_put_int(&e->output, 1);
 502         buffer_put_char(&e->output,
 503             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 504 }
 505
 506 static void
 507 process_remove_smartcard_key(SocketEntry *e)
 508 {
 509         Key *k = NULL;
 510         int success = 0;
 511         char *sc_reader_id = NULL;
 512
 513         sc_reader_id = buffer_get_string(&e->input, NULL);
 514         k = sc_get_key(sc_reader_id);
 515         xfree(sc_reader_id);
 516
 517         if (k == NULL) {
 518                 error("sc_get_pubkey failed");
 519         } else {
 520                 Identity *id;
 521                 k->type = KEY_RSA1;
 522                 id = lookup_identity(k, 1);
 523                 if (id != NULL) {
 524                         Idtab *tab = idtab_lookup(1);
 525                         TAILQ_REMOVE(&tab->idlist, id, next);
 526                         free_identity(id);
 527                         tab->nentries--;
 528                         success = 1;
 529                 }
 530                 k->type = KEY_RSA;
 531                 id = lookup_identity(k, 2);
 532                 if (id != NULL) {
 533                         Idtab *tab = idtab_lookup(2);
 534                         TAILQ_REMOVE(&tab->idlist, id, next);
 535                         free_identity(id);
 536                         tab->nentries--;
 537                         success = 1;
 538                 }
 539                 key_free(k);
 540         }
 541
 542         buffer_put_int(&e->output, 1);
 543         buffer_put_char(&e->output,
 544             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 545 }
 546 #endif /* SMARTCARD */
 547
 548 /* dispatch incoming messages */
 549
 550 static void
 551 process_message(SocketEntry *e)
 552 {
 553         u_int msg_len;
 554         u_int type;
 555         u_char *cp;
 556         if (buffer_len(&e->input) < 5)
 557                 return;         /* Incomplete message. */
 558         cp = buffer_ptr(&e->input);
 559         msg_len = GET_32BIT(cp);
 560         if (msg_len > 256 * 1024) {
 561                 shutdown(e->fd, SHUT_RDWR);
 562                 close(e->fd);
 563                 e->type = AUTH_UNUSED;
 564                 return;
 565         }
 566         if (buffer_len(&e->input) < msg_len + 4)
 567                 return;
 568         buffer_consume(&e->input, 4);
 569         type = buffer_get_char(&e->input);
 570
 571         debug("type %d", type);
 572         switch (type) {
 573         /* ssh1 */
 574         case SSH_AGENTC_RSA_CHALLENGE:
 575                 process_authentication_challenge1(e);
 576                 break;
 577         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 578                 process_request_identities(e, 1);
 579                 break;
 580         case SSH_AGENTC_ADD_RSA_IDENTITY:
 581                 process_add_identity(e, 1);
 582                 break;
 583         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 584                 process_remove_identity(e, 1);
 585                 break;
 586         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 587                 process_remove_all_identities(e, 1);
 588                 break;
 589         /* ssh2 */
 590         case SSH2_AGENTC_SIGN_REQUEST:
 591                 process_sign_request2(e);
 592                 break;
 593         case SSH2_AGENTC_REQUEST_IDENTITIES:
 594                 process_request_identities(e, 2);
 595                 break;
 596         case SSH2_AGENTC_ADD_IDENTITY:
 597                 process_add_identity(e, 2);
 598                 break;
 599         case SSH2_AGENTC_REMOVE_IDENTITY:
 600                 process_remove_identity(e, 2);
 601                 break;
 602         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 603                 process_remove_all_identities(e, 2);
 604                 break;
 605 #ifdef SMARTCARD
 606         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 607                 process_add_smartcard_key(e);
 608                 break;
 609         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 610                 process_remove_smartcard_key(e);
 611                 break;
 612 #endif /* SMARTCARD */
 613         default:
 614                 /* Unknown message.  Respond with failure. */
 615                 error("Unknown message %d", type);
 616                 buffer_clear(&e->input);
 617                 buffer_put_int(&e->output, 1);
 618                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 619                 break;
 620         }
 621 }
 622
 623 static void
 624 new_socket(sock_type type, int fd)
 625 {
 626         u_int i, old_alloc;
 627         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 628                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 629
 630         if (fd > max_fd)
 631                 max_fd = fd;
 632
 633         for (i = 0; i < sockets_alloc; i++)
 634                 if (sockets[i].type == AUTH_UNUSED) {
 635                         sockets[i].fd = fd;
 636                         sockets[i].type = type;
 637                         buffer_init(&sockets[i].input);
 638                         buffer_init(&sockets[i].output);
 639                         return;
 640                 }
 641         old_alloc = sockets_alloc;
 642         sockets_alloc += 10;
 643         if (sockets)
 644                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 645         else
 646                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 647         for (i = old_alloc; i < sockets_alloc; i++)
 648                 sockets[i].type = AUTH_UNUSED;
 649         sockets[old_alloc].type = type;
 650         sockets[old_alloc].fd = fd;
 651         buffer_init(&sockets[old_alloc].input);
 652         buffer_init(&sockets[old_alloc].output);
 653 }
 654
 655 static int
 656 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 657 {
 658         u_int i, sz;
 659         int n = 0;
 660
 661         for (i = 0; i < sockets_alloc; i++) {
 662                 switch (sockets[i].type) {
 663                 case AUTH_SOCKET:
 664                 case AUTH_CONNECTION:
 665                         n = MAX(n, sockets[i].fd);
 666                         break;
 667                 case AUTH_UNUSED:
 668                         break;
 669                 default:
 670                         fatal("Unknown socket type %d", sockets[i].type);
 671                         break;
 672                 }
 673         }
 674
 675         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 676         if (*fdrp == NULL || sz > *nallocp) {
 677                 if (*fdrp)
 678                         xfree(*fdrp);
 679                 if (*fdwp)
 680                         xfree(*fdwp);
 681                 *fdrp = xmalloc(sz);
 682                 *fdwp = xmalloc(sz);
 683                 *nallocp = sz;
 684         }
 685         if (n < *fdl)
 686                 debug("XXX shrink: %d < %d", n, *fdl);
 687         *fdl = n;
 688         memset(*fdrp, 0, sz);
 689         memset(*fdwp, 0, sz);
 690
 691         for (i = 0; i < sockets_alloc; i++) {
 692                 switch (sockets[i].type) {
 693                 case AUTH_SOCKET:
 694                 case AUTH_CONNECTION:
 695                         FD_SET(sockets[i].fd, *fdrp);
 696                         if (buffer_len(&sockets[i].output) > 0)
 697                                 FD_SET(sockets[i].fd, *fdwp);
 698                         break;
 699                 default:
 700                         break;
 701                 }
 702         }
 703         return (1);
 704 }
 705
 706 static void
 707 after_select(fd_set *readset, fd_set *writeset)
 708 {
 709         u_int i;
 710         int len, sock;
 711         socklen_t slen;
 712         char buf[1024];
 713         struct sockaddr_un sunaddr;
 714
 715         for (i = 0; i < sockets_alloc; i++)
 716                 switch (sockets[i].type) {
 717                 case AUTH_UNUSED:
 718                         break;
 719                 case AUTH_SOCKET:
 720                         if (FD_ISSET(sockets[i].fd, readset)) {
 721                                 slen = sizeof(sunaddr);
 722                                 sock = accept(sockets[i].fd,
 723                                     (struct sockaddr *) &sunaddr, &slen);
 724                                 if (sock < 0) {
 725                                         perror("accept from AUTH_SOCKET");
 726                                         break;
 727                                 }
 728                                 new_socket(AUTH_CONNECTION, sock);
 729                         }
 730                         break;
 731                 case AUTH_CONNECTION:
 732                         if (buffer_len(&sockets[i].output) > 0 &&
 733                             FD_ISSET(sockets[i].fd, writeset)) {
 734                                 do {
 735                                         len = write(sockets[i].fd,
 736                                             buffer_ptr(&sockets[i].output),
 737                                             buffer_len(&sockets[i].output));
 738                                         if (len == -1 && (errno == EAGAIN ||
 739                                             errno == EINTR))
 740                                                 continue;
 741                                         break;
 742                                 } while (1);
 743                                 if (len <= 0) {
 744                                         shutdown(sockets[i].fd, SHUT_RDWR);
 745                                         close(sockets[i].fd);
 746                                         sockets[i].type = AUTH_UNUSED;
 747                                         buffer_free(&sockets[i].input);
 748                                         buffer_free(&sockets[i].output);
 749                                         break;
 750                                 }
 751                                 buffer_consume(&sockets[i].output, len);
 752                         }
 753                         if (FD_ISSET(sockets[i].fd, readset)) {
 754                                 do {
 755                                         len = read(sockets[i].fd, buf, sizeof(buf));
 756                                         if (len == -1 && (errno == EAGAIN ||
 757                                             errno == EINTR))
 758                                                 continue;
 759                                         break;
 760                                 } while (1);
 761                                 if (len <= 0) {
 762                                         shutdown(sockets[i].fd, SHUT_RDWR);
 763                                         close(sockets[i].fd);
 764                                         sockets[i].type = AUTH_UNUSED;
 765                                         buffer_free(&sockets[i].input);
 766                                         buffer_free(&sockets[i].output);
 767                                         break;
 768                                 }
 769                                 buffer_append(&sockets[i].input, buf, len);
 770                                 process_message(&sockets[i]);
 771                         }
 772                         break;
 773                 default:
 774                         fatal("Unknown type %d", sockets[i].type);
 775                 }
 776 }
 777
 778 static void
 779 cleanup_socket(void)
 780 {
 781         if (socket_name[0])
 782                 unlink(socket_name);
 783         if (socket_dir[0])
 784                 rmdir(socket_dir);
 785 }
 786
 787 static void
 788 cleanup_exit(int i)
 789 {
 790         cleanup_socket();
 791         exit(i);
 792 }
 793
 794 static void
 795 cleanup_handler(int sig)
 796 {
 797         cleanup_socket();
 798         _exit(2);
 799 }
 800
 801 static void
 802 check_parent_exists(int sig)
 803 {
 804         int save_errno = errno;
 805
 806         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 807                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 808                 cleanup_handler(sig); /* safe */
 809         }
 810         signal(SIGALRM, check_parent_exists);
 811         alarm(10);
 812         errno = save_errno;
 813 }
 814
 815 static void
 816 usage(void)
 817 {
 818         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 819             __progname);
 820         fprintf(stderr, "Options:\n");
 821         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 822         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 823         fprintf(stderr, "  -k          Kill the current agent.\n");
 824         fprintf(stderr, "  -d          Debug mode.\n");
 825         exit(1);
 826 }
 827
 828 int
 829 main(int ac, char **av)
 830 {
 831         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 832         struct sockaddr_un sunaddr;
 833 #ifdef HAVE_SETRLIMIT
 834         struct rlimit rlim;
 835 #endif
 836 #ifdef HAVE_CYGWIN
 837         int prev_mask;
 838 #endif
 839         pid_t pid;
 840         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 841         extern int optind;
 842         fd_set *readsetp = NULL, *writesetp = NULL;
 843
 844         SSLeay_add_all_algorithms();
 845
 846         __progname = get_progname(av[0]);
 847         init_rng();
 848         seed_rng();
 849
 850 #ifdef __GNU_LIBRARY__
 851         while ((ch = getopt(ac, av, "+cdks")) != -1) {
 852 #else /* __GNU_LIBRARY__ */
 853         while ((ch = getopt(ac, av, "cdks")) != -1) {
 854 #endif /* __GNU_LIBRARY__ */
 855                 switch (ch) {
 856                 case 'c':
 857                         if (s_flag)
 858                                 usage();
 859                         c_flag++;
 860                         break;
 861                 case 'k':
 862                         k_flag++;
 863                         break;
 864                 case 's':
 865                         if (c_flag)
 866                                 usage();
 867                         s_flag++;
 868                         break;
 869                 case 'd':
 870                         if (d_flag)
 871                                 usage();
 872                         d_flag++;
 873                         break;
 874                 default:
 875                         usage();
 876                 }
 877         }
 878         ac -= optind;
 879         av += optind;
 880
 881         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
 882                 usage();
 883
 884         if (ac == 0 && !c_flag && !k_flag && !s_flag && !d_flag) {
 885                 shell = getenv("SHELL");
 886                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 887                         c_flag = 1;
 888         }
 889         if (k_flag) {
 890                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 891                 if (pidstr == NULL) {
 892                         fprintf(stderr, "%s not set, cannot kill agent\n",
 893                             SSH_AGENTPID_ENV_NAME);
 894                         exit(1);
 895                 }
 896                 pid = atoi(pidstr);
 897                 if (pid < 1) {
 898                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 899                             SSH_AGENTPID_ENV_NAME, pidstr);
 900                         exit(1);
 901                 }
 902                 if (kill(pid, SIGTERM) == -1) {
 903                         perror("kill");
 904                         exit(1);
 905                 }
 906                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 907                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 908                 printf(format, SSH_AGENTPID_ENV_NAME);
 909                 printf("echo Agent pid %d killed;\n", pid);
 910                 exit(0);
 911         }
 912         parent_pid = getpid();
 913
 914         /* Create private directory for agent socket */
 915         strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 916         if (mkdtemp(socket_dir) == NULL) {
 917                 perror("mkdtemp: private socket dir");
 918                 exit(1);
 919         }
 920         snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 921             parent_pid);
 922
 923         /*
 924          * Create socket early so it will exist before command gets run from
 925          * the parent.
 926          */
 927         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 928         if (sock < 0) {
 929                 perror("socket");
 930                 cleanup_exit(1);
 931         }
 932         memset(&sunaddr, 0, sizeof(sunaddr));
 933         sunaddr.sun_family = AF_UNIX;
 934         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 935 #ifdef HAVE_CYGWIN
 936         prev_mask = umask(0177);
 937 #endif
 938         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 939                 perror("bind");
 940 #ifdef HAVE_CYGWIN
 941                 umask(prev_mask);
 942 #endif
 943                 cleanup_exit(1);
 944         }
 945 #ifdef HAVE_CYGWIN
 946         umask(prev_mask);
 947 #endif
 948         if (listen(sock, 5) < 0) {
 949                 perror("listen");
 950                 cleanup_exit(1);
 951         }
 952
 953         /*
 954          * Fork, and have the parent execute the command, if any, or present
 955          * the socket data.  The child continues as the authentication agent.
 956          */
 957         if (d_flag) {
 958                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
 959                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 960                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 961                     SSH_AUTHSOCKET_ENV_NAME);
 962                 printf("echo Agent pid %d;\n", parent_pid);
 963                 goto skip;
 964         }
 965         pid = fork();
 966         if (pid == -1) {
 967                 perror("fork");
 968                 exit(1);
 969         }
 970         if (pid != 0) {         /* Parent - execute the given command. */
 971                 close(sock);
 972                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 973                 if (ac == 0) {
 974                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 975                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 976                             SSH_AUTHSOCKET_ENV_NAME);
 977                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 978                             SSH_AGENTPID_ENV_NAME);
 979                         printf("echo Agent pid %d;\n", pid);
 980                         exit(0);
 981                 }
 982                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 983                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 984                         perror("setenv");
 985                         exit(1);
 986                 }
 987                 execvp(av[0], av);
 988                 perror(av[0]);
 989                 exit(1);
 990         }
 991
 992         if (setsid() == -1) {
 993                 perror("setsid");
 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                 perror("setrlimit rlimit_core failed");
1007                 cleanup_exit(1);
1008         }
1009 #endif
1010
1011 skip:
1012         if (atexit(cleanup_socket) < 0) {
1013                 perror("atexit");
1014                 cleanup_exit(1);
1015         }
1016         new_socket(AUTH_SOCKET, sock);
1017         if (ac > 0) {
1018                 signal(SIGALRM, check_parent_exists);
1019                 alarm(10);
1020         }
1021         idtab_init();
1022         if (!d_flag)
1023                 signal(SIGINT, SIG_IGN);
1024         signal(SIGPIPE, SIG_IGN);
1025         signal(SIGHUP, cleanup_handler);
1026         signal(SIGTERM, cleanup_handler);
1027         nalloc = 0;
1028
1029         while (1) {
1030                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1031                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1032                         if (errno == EINTR)
1033                                 continue;
1034                         exit(1);
1035                 }
1036                 after_select(readsetp, writesetp);
1037         }
1038         /* NOTREACHED */
1039 }