ssh-agent.c

   1 /*      $OpenBSD: ssh-agent.c,v 1.79 2002/01/18 18:14:17 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 1.79 2002/01/18 18:14:17 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 "packet.h"
  57 #include "getput.h"
  58 #include "mpaux.h"
  59 #include "key.h"
  60 #include "authfd.h"
  61 #include "cipher.h"
  62 #include "kex.h"
  63 #include "compat.h"
  64 #include "log.h"
  65
  66 #ifdef SMARTCARD
  67 #include <openssl/engine.h>
  68 #include "scard.h"
  69 #endif
  70
  71 typedef enum {
  72         AUTH_UNUSED,
  73         AUTH_SOCKET,
  74         AUTH_CONNECTION
  75 } sock_type;
  76
  77 typedef struct {
  78         int fd;
  79         sock_type type;
  80         Buffer input;
  81         Buffer output;
  82 } SocketEntry;
  83
  84 u_int sockets_alloc = 0;
  85 SocketEntry *sockets = NULL;
  86
  87 typedef struct identity {
  88         TAILQ_ENTRY(identity) next;
  89         Key *key;
  90         char *comment;
  91 } Identity;
  92
  93 typedef struct {
  94         int nentries;
  95         TAILQ_HEAD(idqueue, identity) idlist;
  96 } Idtab;
  97
  98 /* private key table, one per protocol version */
  99 Idtab idtable[3];
 100
 101 int max_fd = 0;
 102
 103 /* pid of shell == parent of agent */
 104 pid_t parent_pid = -1;
 105
 106 /* pathname and directory for AUTH_SOCKET */
 107 char socket_name[1024];
 108 char socket_dir[1024];
 109
 110 #ifdef HAVE___PROGNAME
 111 extern char *__progname;
 112 #else
 113 char *__progname;
 114 #endif
 115
 116 static void
 117 idtab_init(void)
 118 {
 119         int i;
 120         for (i = 0; i <=2; i++) {
 121                 TAILQ_INIT(&idtable[i].idlist);
 122                 idtable[i].nentries = 0;
 123         }
 124 }
 125
 126 /* return private key table for requested protocol version */
 127 static Idtab *
 128 idtab_lookup(int version)
 129 {
 130         if (version < 1 || version > 2)
 131                 fatal("internal error, bad protocol version %d", version);
 132         return &idtable[version];
 133 }
 134
 135 /* return matching private key for given public key */
 136 static Identity *
 137 lookup_identity(Key *key, int version)
 138 {
 139         Identity *id;
 140
 141         Idtab *tab = idtab_lookup(version);
 142         TAILQ_FOREACH(id, &tab->idlist, next) {
 143                 if (key_equal(key, id->key))
 144                         return (id);
 145         }
 146         return (NULL);
 147 }
 148
 149 static void
 150 free_identity(Identity *id)
 151 {
 152         key_free(id->key);
 153         xfree(id->comment);
 154         xfree(id);
 155 }
 156
 157 /* send list of supported public keys to 'client' */
 158 static void
 159 process_request_identities(SocketEntry *e, int version)
 160 {
 161         Idtab *tab = idtab_lookup(version);
 162         Buffer msg;
 163         Identity *id;
 164
 165         buffer_init(&msg);
 166         buffer_put_char(&msg, (version == 1) ?
 167             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 168         buffer_put_int(&msg, tab->nentries);
 169         TAILQ_FOREACH(id, &tab->idlist, next) {
 170                 if (id->key->type == KEY_RSA1) {
 171                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 172                         buffer_put_bignum(&msg, id->key->rsa->e);
 173                         buffer_put_bignum(&msg, id->key->rsa->n);
 174                 } else {
 175                         u_char *blob;
 176                         u_int blen;
 177                         key_to_blob(id->key, &blob, &blen);
 178                         buffer_put_string(&msg, blob, blen);
 179                         xfree(blob);
 180                 }
 181                 buffer_put_cstring(&msg, id->comment);
 182         }
 183         buffer_put_int(&e->output, buffer_len(&msg));
 184         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 185         buffer_free(&msg);
 186 }
 187
 188 /* ssh1 only */
 189 static void
 190 process_authentication_challenge1(SocketEntry *e)
 191 {
 192         Identity *id;
 193         Key *key;
 194         BIGNUM *challenge;
 195         int i, len;
 196         Buffer msg;
 197         MD5_CTX md;
 198         u_char buf[32], mdbuf[16], session_id[16];
 199         u_int response_type;
 200
 201         buffer_init(&msg);
 202         key = key_new(KEY_RSA1);
 203         if ((challenge = BN_new()) == NULL)
 204                 fatal("process_authentication_challenge1: BN_new failed");
 205
 206         buffer_get_int(&e->input);                              /* ignored */
 207         buffer_get_bignum(&e->input, key->rsa->e);
 208         buffer_get_bignum(&e->input, key->rsa->n);
 209         buffer_get_bignum(&e->input, challenge);
 210
 211         /* Only protocol 1.1 is supported */
 212         if (buffer_len(&e->input) == 0)
 213                 goto failure;
 214         buffer_get(&e->input, session_id, 16);
 215         response_type = buffer_get_int(&e->input);
 216         if (response_type != 1)
 217                 goto failure;
 218
 219         id = lookup_identity(key, 1);
 220         if (id != NULL) {
 221                 Key *private = id->key;
 222                 /* Decrypt the challenge using the private key. */
 223                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 224                         goto failure;
 225
 226                 /* The response is MD5 of decrypted challenge plus session id. */
 227                 len = BN_num_bytes(challenge);
 228                 if (len <= 0 || len > 32) {
 229                         log("process_authentication_challenge: bad challenge length %d", len);
 230                         goto failure;
 231                 }
 232                 memset(buf, 0, 32);
 233                 BN_bn2bin(challenge, buf + 32 - len);
 234                 MD5_Init(&md);
 235                 MD5_Update(&md, buf, 32);
 236                 MD5_Update(&md, session_id, 16);
 237                 MD5_Final(mdbuf, &md);
 238
 239                 /* Send the response. */
 240                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 241                 for (i = 0; i < 16; i++)
 242                         buffer_put_char(&msg, mdbuf[i]);
 243                 goto send;
 244         }
 245
 246 failure:
 247         /* Unknown identity or protocol error.  Send failure. */
 248         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 249 send:
 250         buffer_put_int(&e->output, buffer_len(&msg));
 251         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 252         key_free(key);
 253         BN_clear_free(challenge);
 254         buffer_free(&msg);
 255 }
 256
 257 /* ssh2 only */
 258 static void
 259 process_sign_request2(SocketEntry *e)
 260 {
 261         extern int datafellows;
 262         Key *key;
 263         u_char *blob, *data, *signature = NULL;
 264         u_int blen, dlen, slen = 0;
 265         int flags;
 266         Buffer msg;
 267         int ok = -1;
 268
 269         datafellows = 0;
 270
 271         blob = buffer_get_string(&e->input, &blen);
 272         data = buffer_get_string(&e->input, &dlen);
 273
 274         flags = buffer_get_int(&e->input);
 275         if (flags & SSH_AGENT_OLD_SIGNATURE)
 276                 datafellows = SSH_BUG_SIGBLOB;
 277
 278         key = key_from_blob(blob, blen);
 279         if (key != NULL) {
 280                 Identity *id = lookup_identity(key, 2);
 281                 if (id != NULL)
 282                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 283         }
 284         key_free(key);
 285         buffer_init(&msg);
 286         if (ok == 0) {
 287                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 288                 buffer_put_string(&msg, signature, slen);
 289         } else {
 290                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 291         }
 292         buffer_put_int(&e->output, buffer_len(&msg));
 293         buffer_append(&e->output, buffer_ptr(&msg),
 294             buffer_len(&msg));
 295         buffer_free(&msg);
 296         xfree(data);
 297         xfree(blob);
 298         if (signature != NULL)
 299                 xfree(signature);
 300 }
 301
 302 /* shared */
 303 static void
 304 process_remove_identity(SocketEntry *e, int version)
 305 {
 306         Key *key = NULL;
 307         u_char *blob;
 308         u_int blen;
 309         u_int bits;
 310         int success = 0;
 311
 312         switch (version) {
 313         case 1:
 314                 key = key_new(KEY_RSA1);
 315                 bits = buffer_get_int(&e->input);
 316                 buffer_get_bignum(&e->input, key->rsa->e);
 317                 buffer_get_bignum(&e->input, key->rsa->n);
 318
 319                 if (bits != key_size(key))
 320                         log("Warning: identity keysize mismatch: actual %d, announced %d",
 321                             key_size(key), bits);
 322                 break;
 323         case 2:
 324                 blob = buffer_get_string(&e->input, &blen);
 325                 key = key_from_blob(blob, blen);
 326                 xfree(blob);
 327                 break;
 328         }
 329         if (key != NULL) {
 330                 Identity *id = lookup_identity(key, version);
 331                 if (id != NULL) {
 332                         /*
 333                          * We have this key.  Free the old key.  Since we
 334                          * don\'t want to leave empty slots in the middle of
 335                          * the array, we actually free the key there and move
 336                          * all the entries between the empty slot and the end
 337                          * of the array.
 338                          */
 339                         Idtab *tab = idtab_lookup(version);
 340                         if (tab->nentries < 1)
 341                                 fatal("process_remove_identity: "
 342                                     "internal error: tab->nentries %d",
 343                                     tab->nentries);
 344                         TAILQ_REMOVE(&tab->idlist, id, next);
 345                         free_identity(id);
 346                         tab->nentries--;
 347                         success = 1;
 348                 }
 349                 key_free(key);
 350         }
 351         buffer_put_int(&e->output, 1);
 352         buffer_put_char(&e->output,
 353             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 354 }
 355
 356 static void
 357 process_remove_all_identities(SocketEntry *e, int version)
 358 {
 359         Idtab *tab = idtab_lookup(version);
 360         Identity *id;
 361
 362         /* Loop over all identities and clear the keys. */
 363         for (id = TAILQ_FIRST(&tab->idlist); id;
 364             id = TAILQ_FIRST(&tab->idlist)) {
 365                 TAILQ_REMOVE(&tab->idlist, id, next);
 366                 free_identity(id);
 367         }
 368
 369         /* Mark that there are no identities. */
 370         tab->nentries = 0;
 371
 372         /* Send success. */
 373         buffer_put_int(&e->output, 1);
 374         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 375         return;
 376 }
 377
 378 static void
 379 process_add_identity(SocketEntry *e, int version)
 380 {
 381         Key *k = NULL;
 382         char *type_name;
 383         char *comment;
 384         int type, success = 0;
 385         Idtab *tab = idtab_lookup(version);
 386
 387         switch (version) {
 388         case 1:
 389                 k = key_new_private(KEY_RSA1);
 390                 buffer_get_int(&e->input);                      /* ignored */
 391                 buffer_get_bignum(&e->input, k->rsa->n);
 392                 buffer_get_bignum(&e->input, k->rsa->e);
 393                 buffer_get_bignum(&e->input, k->rsa->d);
 394                 buffer_get_bignum(&e->input, k->rsa->iqmp);
 395
 396                 /* SSH and SSL have p and q swapped */
 397                 buffer_get_bignum(&e->input, k->rsa->q);        /* p */
 398                 buffer_get_bignum(&e->input, k->rsa->p);        /* q */
 399
 400                 /* Generate additional parameters */
 401                 rsa_generate_additional_parameters(k->rsa);
 402                 break;
 403         case 2:
 404                 type_name = buffer_get_string(&e->input, NULL);
 405                 type = key_type_from_name(type_name);
 406                 xfree(type_name);
 407                 switch (type) {
 408                 case KEY_DSA:
 409                         k = key_new_private(type);
 410                         buffer_get_bignum2(&e->input, k->dsa->p);
 411                         buffer_get_bignum2(&e->input, k->dsa->q);
 412                         buffer_get_bignum2(&e->input, k->dsa->g);
 413                         buffer_get_bignum2(&e->input, k->dsa->pub_key);
 414                         buffer_get_bignum2(&e->input, k->dsa->priv_key);
 415                         break;
 416                 case KEY_RSA:
 417                         k = key_new_private(type);
 418                         buffer_get_bignum2(&e->input, k->rsa->n);
 419                         buffer_get_bignum2(&e->input, k->rsa->e);
 420                         buffer_get_bignum2(&e->input, k->rsa->d);
 421                         buffer_get_bignum2(&e->input, k->rsa->iqmp);
 422                         buffer_get_bignum2(&e->input, k->rsa->p);
 423                         buffer_get_bignum2(&e->input, k->rsa->q);
 424
 425                         /* Generate additional parameters */
 426                         rsa_generate_additional_parameters(k->rsa);
 427                         break;
 428                 default:
 429                         buffer_clear(&e->input);
 430                         goto send;
 431                 }
 432                 break;
 433         }
 434         comment = buffer_get_string(&e->input, NULL);
 435         if (k == NULL) {
 436                 xfree(comment);
 437                 goto send;
 438         }
 439         success = 1;
 440         if (lookup_identity(k, version) == NULL) {
 441                 Identity *id = xmalloc(sizeof(Identity));
 442                 id->key = k;
 443                 id->comment = comment;
 444                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 445                 /* Increment the number of identities. */
 446                 tab->nentries++;
 447         } else {
 448                 key_free(k);
 449                 xfree(comment);
 450         }
 451 send:
 452         buffer_put_int(&e->output, 1);
 453         buffer_put_char(&e->output,
 454             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 455 }
 456
 457
 458 #ifdef SMARTCARD
 459 static void
 460 process_add_smartcard_key (SocketEntry *e)
 461 {
 462         Idtab *tab;
 463         Key *n = NULL, *k = NULL;
 464         char *sc_reader_id = NULL;
 465         int success = 0;
 466
 467         sc_reader_id = buffer_get_string(&e->input, NULL);
 468         k = sc_get_key(sc_reader_id);
 469         xfree(sc_reader_id);
 470
 471         if (k == NULL) {
 472                 error("sc_get_pubkey failed");
 473                 goto send;
 474         }
 475         success = 1;
 476
 477         tab = idtab_lookup(1);
 478         k->type = KEY_RSA1;
 479         if (lookup_identity(k, 1) == NULL) {
 480                 Identity *id = xmalloc(sizeof(Identity));
 481                 n = key_new(KEY_RSA1);
 482                 BN_copy(n->rsa->n, k->rsa->n);
 483                 BN_copy(n->rsa->e, k->rsa->e);
 484                 RSA_set_method(n->rsa, sc_get_engine());
 485                 id->key = n;
 486                 id->comment = xstrdup("rsa1 smartcard");
 487                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 488                 tab->nentries++;
 489         }
 490         k->type = KEY_RSA;
 491         tab = idtab_lookup(2);
 492         if (lookup_identity(k, 2) == NULL) {
 493                 Identity *id = xmalloc(sizeof(Identity));
 494                 n = key_new(KEY_RSA);
 495                 BN_copy(n->rsa->n, k->rsa->n);
 496                 BN_copy(n->rsa->e, k->rsa->e);
 497                 RSA_set_method(n->rsa, sc_get_engine());
 498                 id->key = n;
 499                 id->comment = xstrdup("rsa smartcard");
 500                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 501                 tab->nentries++;
 502         }
 503         key_free(k);
 504 send:
 505         buffer_put_int(&e->output, 1);
 506         buffer_put_char(&e->output,
 507             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 508 }
 509
 510 static void
 511 process_remove_smartcard_key(SocketEntry *e)
 512 {
 513         Key *k = NULL;
 514         int success = 0;
 515         char *sc_reader_id = NULL;
 516
 517         sc_reader_id = buffer_get_string(&e->input, NULL);
 518         k = sc_get_key(sc_reader_id);
 519         xfree(sc_reader_id);
 520
 521         if (k == NULL) {
 522                 error("sc_get_pubkey failed");
 523         } else {
 524                 Identity *id;
 525                 k->type = KEY_RSA1;
 526                 id = lookup_identity(k, 1);
 527                 if (id != NULL) {
 528                         Idtab *tab = idtab_lookup(1);
 529                         TAILQ_REMOVE(&tab->idlist, id, next);
 530                         free_identity(id);
 531                         tab->nentries--;
 532                         success = 1;
 533                 }
 534                 k->type = KEY_RSA;
 535                 id = lookup_identity(k, 2);
 536                 if (id != NULL) {
 537                         Idtab *tab = idtab_lookup(2);
 538                         TAILQ_REMOVE(&tab->idlist, id, next);
 539                         free_identity(id);
 540                         tab->nentries--;
 541                         success = 1;
 542                 }
 543                 key_free(k);
 544         }
 545
 546         buffer_put_int(&e->output, 1);
 547         buffer_put_char(&e->output,
 548             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 549 }
 550 #endif /* SMARTCARD */
 551
 552 /* dispatch incoming messages */
 553
 554 static void
 555 process_message(SocketEntry *e)
 556 {
 557         u_int msg_len;
 558         u_int type;
 559         u_char *cp;
 560         if (buffer_len(&e->input) < 5)
 561                 return;         /* Incomplete message. */
 562         cp = buffer_ptr(&e->input);
 563         msg_len = GET_32BIT(cp);
 564         if (msg_len > 256 * 1024) {
 565                 shutdown(e->fd, SHUT_RDWR);
 566                 close(e->fd);
 567                 e->type = AUTH_UNUSED;
 568                 return;
 569         }
 570         if (buffer_len(&e->input) < msg_len + 4)
 571                 return;
 572         buffer_consume(&e->input, 4);
 573         type = buffer_get_char(&e->input);
 574
 575         debug("type %d", type);
 576         switch (type) {
 577         /* ssh1 */
 578         case SSH_AGENTC_RSA_CHALLENGE:
 579                 process_authentication_challenge1(e);
 580                 break;
 581         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 582                 process_request_identities(e, 1);
 583                 break;
 584         case SSH_AGENTC_ADD_RSA_IDENTITY:
 585                 process_add_identity(e, 1);
 586                 break;
 587         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 588                 process_remove_identity(e, 1);
 589                 break;
 590         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 591                 process_remove_all_identities(e, 1);
 592                 break;
 593         /* ssh2 */
 594         case SSH2_AGENTC_SIGN_REQUEST:
 595                 process_sign_request2(e);
 596                 break;
 597         case SSH2_AGENTC_REQUEST_IDENTITIES:
 598                 process_request_identities(e, 2);
 599                 break;
 600         case SSH2_AGENTC_ADD_IDENTITY:
 601                 process_add_identity(e, 2);
 602                 break;
 603         case SSH2_AGENTC_REMOVE_IDENTITY:
 604                 process_remove_identity(e, 2);
 605                 break;
 606         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 607                 process_remove_all_identities(e, 2);
 608                 break;
 609 #ifdef SMARTCARD
 610         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 611                 process_add_smartcard_key(e);
 612                 break;
 613         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 614                 process_remove_smartcard_key(e);
 615                 break;
 616 #endif /* SMARTCARD */
 617         default:
 618                 /* Unknown message.  Respond with failure. */
 619                 error("Unknown message %d", type);
 620                 buffer_clear(&e->input);
 621                 buffer_put_int(&e->output, 1);
 622                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 623                 break;
 624         }
 625 }
 626
 627 static void
 628 new_socket(sock_type type, int fd)
 629 {
 630         u_int i, old_alloc;
 631         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 632                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 633
 634         if (fd > max_fd)
 635                 max_fd = fd;
 636
 637         for (i = 0; i < sockets_alloc; i++)
 638                 if (sockets[i].type == AUTH_UNUSED) {
 639                         sockets[i].fd = fd;
 640                         sockets[i].type = type;
 641                         buffer_init(&sockets[i].input);
 642                         buffer_init(&sockets[i].output);
 643                         return;
 644                 }
 645         old_alloc = sockets_alloc;
 646         sockets_alloc += 10;
 647         if (sockets)
 648                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 649         else
 650                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 651         for (i = old_alloc; i < sockets_alloc; i++)
 652                 sockets[i].type = AUTH_UNUSED;
 653         sockets[old_alloc].type = type;
 654         sockets[old_alloc].fd = fd;
 655         buffer_init(&sockets[old_alloc].input);
 656         buffer_init(&sockets[old_alloc].output);
 657 }
 658
 659 static int
 660 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 661 {
 662         u_int i, sz;
 663         int n = 0;
 664
 665         for (i = 0; i < sockets_alloc; i++) {
 666                 switch (sockets[i].type) {
 667                 case AUTH_SOCKET:
 668                 case AUTH_CONNECTION:
 669                         n = MAX(n, sockets[i].fd);
 670                         break;
 671                 case AUTH_UNUSED:
 672                         break;
 673                 default:
 674                         fatal("Unknown socket type %d", sockets[i].type);
 675                         break;
 676                 }
 677         }
 678
 679         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 680         if (*fdrp == NULL || sz > *nallocp) {
 681                 if (*fdrp)
 682                         xfree(*fdrp);
 683                 if (*fdwp)
 684                         xfree(*fdwp);
 685                 *fdrp = xmalloc(sz);
 686                 *fdwp = xmalloc(sz);
 687                 *nallocp = sz;
 688         }
 689         if (n < *fdl)
 690                 debug("XXX shrink: %d < %d", n, *fdl);
 691         *fdl = n;
 692         memset(*fdrp, 0, sz);
 693         memset(*fdwp, 0, sz);
 694
 695         for (i = 0; i < sockets_alloc; i++) {
 696                 switch (sockets[i].type) {
 697                 case AUTH_SOCKET:
 698                 case AUTH_CONNECTION:
 699                         FD_SET(sockets[i].fd, *fdrp);
 700                         if (buffer_len(&sockets[i].output) > 0)
 701                                 FD_SET(sockets[i].fd, *fdwp);
 702                         break;
 703                 default:
 704                         break;
 705                 }
 706         }
 707         return (1);
 708 }
 709
 710 static void
 711 after_select(fd_set *readset, fd_set *writeset)
 712 {
 713         u_int i;
 714         int len, sock;
 715         socklen_t slen;
 716         char buf[1024];
 717         struct sockaddr_un sunaddr;
 718
 719         for (i = 0; i < sockets_alloc; i++)
 720                 switch (sockets[i].type) {
 721                 case AUTH_UNUSED:
 722                         break;
 723                 case AUTH_SOCKET:
 724                         if (FD_ISSET(sockets[i].fd, readset)) {
 725                                 slen = sizeof(sunaddr);
 726                                 sock = accept(sockets[i].fd,
 727                                     (struct sockaddr *) &sunaddr, &slen);
 728                                 if (sock < 0) {
 729                                         perror("accept from AUTH_SOCKET");
 730                                         break;
 731                                 }
 732                                 new_socket(AUTH_CONNECTION, sock);
 733                         }
 734                         break;
 735                 case AUTH_CONNECTION:
 736                         if (buffer_len(&sockets[i].output) > 0 &&
 737                             FD_ISSET(sockets[i].fd, writeset)) {
 738                                 do {
 739                                         len = write(sockets[i].fd,
 740                                             buffer_ptr(&sockets[i].output),
 741                                             buffer_len(&sockets[i].output));
 742                                         if (len == -1 && (errno == EAGAIN ||
 743                                             errno == EINTR))
 744                                                 continue;
 745                                         break;
 746                                 } while (1);
 747                                 if (len <= 0) {
 748                                         shutdown(sockets[i].fd, SHUT_RDWR);
 749                                         close(sockets[i].fd);
 750                                         sockets[i].type = AUTH_UNUSED;
 751                                         buffer_free(&sockets[i].input);
 752                                         buffer_free(&sockets[i].output);
 753                                         break;
 754                                 }
 755                                 buffer_consume(&sockets[i].output, len);
 756                         }
 757                         if (FD_ISSET(sockets[i].fd, readset)) {
 758                                 do {
 759                                         len = read(sockets[i].fd, buf, sizeof(buf));
 760                                         if (len == -1 && (errno == EAGAIN ||
 761                                             errno == EINTR))
 762                                                 continue;
 763                                         break;
 764                                 } while (1);
 765                                 if (len <= 0) {
 766                                         shutdown(sockets[i].fd, SHUT_RDWR);
 767                                         close(sockets[i].fd);
 768                                         sockets[i].type = AUTH_UNUSED;
 769                                         buffer_free(&sockets[i].input);
 770                                         buffer_free(&sockets[i].output);
 771                                         break;
 772                                 }
 773                                 buffer_append(&sockets[i].input, buf, len);
 774                                 process_message(&sockets[i]);
 775                         }
 776                         break;
 777                 default:
 778                         fatal("Unknown type %d", sockets[i].type);
 779                 }
 780 }
 781
 782 static void
 783 cleanup_socket(void)
 784 {
 785         if (socket_name[0])
 786                 unlink(socket_name);
 787         if (socket_dir[0])
 788                 rmdir(socket_dir);
 789 }
 790
 791 static void
 792 cleanup_exit(int i)
 793 {
 794         cleanup_socket();
 795         exit(i);
 796 }
 797
 798 static void
 799 cleanup_handler(int sig)
 800 {
 801         cleanup_socket();
 802         _exit(2);
 803 }
 804
 805 static void
 806 check_parent_exists(int sig)
 807 {
 808         int save_errno = errno;
 809
 810         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 811                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 812                 cleanup_handler(sig); /* safe */
 813         }
 814         signal(SIGALRM, check_parent_exists);
 815         alarm(10);
 816         errno = save_errno;
 817 }
 818
 819 static void
 820 usage(void)
 821 {
 822         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 823             __progname);
 824         fprintf(stderr, "Options:\n");
 825         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 826         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 827         fprintf(stderr, "  -k          Kill the current agent.\n");
 828         fprintf(stderr, "  -d          Debug mode.\n");
 829         exit(1);
 830 }
 831
 832 int
 833 main(int ac, char **av)
 834 {
 835         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 836         struct sockaddr_un sunaddr;
 837 #ifdef HAVE_SETRLIMIT
 838         struct rlimit rlim;
 839 #endif
 840 #ifdef HAVE_CYGWIN
 841         int prev_mask;
 842 #endif
 843         pid_t pid;
 844         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 845         extern int optind;
 846         fd_set *readsetp = NULL, *writesetp = NULL;
 847
 848         SSLeay_add_all_algorithms();
 849
 850         __progname = get_progname(av[0]);
 851         init_rng();
 852         seed_rng();
 853
 854 #ifdef __GNU_LIBRARY__
 855         while ((ch = getopt(ac, av, "+cdks")) != -1) {
 856 #else /* __GNU_LIBRARY__ */
 857         while ((ch = getopt(ac, av, "cdks")) != -1) {
 858 #endif /* __GNU_LIBRARY__ */
 859                 switch (ch) {
 860                 case 'c':
 861                         if (s_flag)
 862                                 usage();
 863                         c_flag++;
 864                         break;
 865                 case 'k':
 866                         k_flag++;
 867                         break;
 868                 case 's':
 869                         if (c_flag)
 870                                 usage();
 871                         s_flag++;
 872                         break;
 873                 case 'd':
 874                         if (d_flag)
 875                                 usage();
 876                         d_flag++;
 877                         break;
 878                 default:
 879                         usage();
 880                 }
 881         }
 882         ac -= optind;
 883         av += optind;
 884
 885         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
 886                 usage();
 887
 888         if (ac == 0 && !c_flag && !k_flag && !s_flag && !d_flag) {
 889                 shell = getenv("SHELL");
 890                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 891                         c_flag = 1;
 892         }
 893         if (k_flag) {
 894                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 895                 if (pidstr == NULL) {
 896                         fprintf(stderr, "%s not set, cannot kill agent\n",
 897                             SSH_AGENTPID_ENV_NAME);
 898                         exit(1);
 899                 }
 900                 pid = atoi(pidstr);
 901                 if (pid < 1) {
 902                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 903                             SSH_AGENTPID_ENV_NAME, pidstr);
 904                         exit(1);
 905                 }
 906                 if (kill(pid, SIGTERM) == -1) {
 907                         perror("kill");
 908                         exit(1);
 909                 }
 910                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 911                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 912                 printf(format, SSH_AGENTPID_ENV_NAME);
 913                 printf("echo Agent pid %d killed;\n", pid);
 914                 exit(0);
 915         }
 916         parent_pid = getpid();
 917
 918         /* Create private directory for agent socket */
 919         strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 920         if (mkdtemp(socket_dir) == NULL) {
 921                 perror("mkdtemp: private socket dir");
 922                 exit(1);
 923         }
 924         snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 925             parent_pid);
 926
 927         /*
 928          * Create socket early so it will exist before command gets run from
 929          * the parent.
 930          */
 931         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 932         if (sock < 0) {
 933                 perror("socket");
 934                 cleanup_exit(1);
 935         }
 936         memset(&sunaddr, 0, sizeof(sunaddr));
 937         sunaddr.sun_family = AF_UNIX;
 938         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 939 #ifdef HAVE_CYGWIN
 940         prev_mask = umask(0177);
 941 #endif
 942         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 943                 perror("bind");
 944 #ifdef HAVE_CYGWIN
 945                 umask(prev_mask);
 946 #endif
 947                 cleanup_exit(1);
 948         }
 949 #ifdef HAVE_CYGWIN
 950         umask(prev_mask);
 951 #endif
 952         if (listen(sock, 5) < 0) {
 953                 perror("listen");
 954                 cleanup_exit(1);
 955         }
 956
 957         /*
 958          * Fork, and have the parent execute the command, if any, or present
 959          * the socket data.  The child continues as the authentication agent.
 960          */
 961         if (d_flag) {
 962                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
 963                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 964                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 965                     SSH_AUTHSOCKET_ENV_NAME);
 966                 printf("echo Agent pid %d;\n", parent_pid);
 967                 goto skip;
 968         }
 969         pid = fork();
 970         if (pid == -1) {
 971                 perror("fork");
 972                 exit(1);
 973         }
 974         if (pid != 0) {         /* Parent - execute the given command. */
 975                 close(sock);
 976                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 977                 if (ac == 0) {
 978                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 979                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 980                             SSH_AUTHSOCKET_ENV_NAME);
 981                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 982                             SSH_AGENTPID_ENV_NAME);
 983                         printf("echo Agent pid %d;\n", pid);
 984                         exit(0);
 985                 }
 986                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 987                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 988                         perror("setenv");
 989                         exit(1);
 990                 }
 991                 execvp(av[0], av);
 992                 perror(av[0]);
 993                 exit(1);
 994         }
 995
 996         if (setsid() == -1) {
 997                 perror("setsid");
 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                 perror("setrlimit rlimit_core failed");
1011                 cleanup_exit(1);
1012         }
1013 #endif
1014
1015 skip:
1016         if (atexit(cleanup_socket) < 0) {
1017                 perror("atexit");
1018                 cleanup_exit(1);
1019         }
1020         new_socket(AUTH_SOCKET, sock);
1021         if (ac > 0) {
1022                 signal(SIGALRM, check_parent_exists);
1023                 alarm(10);
1024         }
1025         idtab_init();
1026         if (!d_flag)
1027                 signal(SIGINT, SIG_IGN);
1028         signal(SIGPIPE, SIG_IGN);
1029         signal(SIGHUP, cleanup_handler);
1030         signal(SIGTERM, cleanup_handler);
1031         nalloc = 0;
1032
1033         while (1) {
1034                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1035                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1036                         if (errno == EINTR)
1037                                 continue;
1038                         exit(1);
1039                 }
1040                 after_select(readsetp, writesetp);
1041         }
1042         /* NOTREACHED */
1043 }