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 #include "openbsd-compat/fake-queue.h"
  38 RCSID("$OpenBSD: ssh-agent.c,v 1.86 2002/06/05 16:08:07 markus Exp $");
  39
  40 #include <openssl/evp.h>
  41 #include <openssl/md5.h>
  42
  43 #include "ssh.h"
  44 #include "rsa.h"
  45 #include "buffer.h"
  46 #include "bufaux.h"
  47 #include "xmalloc.h"
  48 #include "getput.h"
  49 #include "key.h"
  50 #include "authfd.h"
  51 #include "compat.h"
  52 #include "log.h"
  53
  54 #ifdef SMARTCARD
  55 #include "scard.h"
  56 #endif
  57
  58 typedef enum {
  59         AUTH_UNUSED,
  60         AUTH_SOCKET,
  61         AUTH_CONNECTION
  62 } sock_type;
  63
  64 typedef struct {
  65         int fd;
  66         sock_type type;
  67         Buffer input;
  68         Buffer output;
  69 } SocketEntry;
  70
  71 u_int sockets_alloc = 0;
  72 SocketEntry *sockets = NULL;
  73
  74 typedef struct identity {
  75         TAILQ_ENTRY(identity) next;
  76         Key *key;
  77         char *comment;
  78 } Identity;
  79
  80 typedef struct {
  81         int nentries;
  82         TAILQ_HEAD(idqueue, identity) idlist;
  83 } Idtab;
  84
  85 /* private key table, one per protocol version */
  86 Idtab idtable[3];
  87
  88 int max_fd = 0;
  89
  90 /* pid of shell == parent of agent */
  91 pid_t parent_pid = -1;
  92
  93 /* pathname and directory for AUTH_SOCKET */
  94 char socket_name[1024];
  95 char socket_dir[1024];
  96
  97 #ifdef HAVE___PROGNAME
  98 extern char *__progname;
  99 #else
 100 char *__progname;
 101 #endif
 102
 103 static void
 104 idtab_init(void)
 105 {
 106         int i;
 107         for (i = 0; i <=2; i++) {
 108                 TAILQ_INIT(&idtable[i].idlist);
 109                 idtable[i].nentries = 0;
 110         }
 111 }
 112
 113 /* return private key table for requested protocol version */
 114 static Idtab *
 115 idtab_lookup(int version)
 116 {
 117         if (version < 1 || version > 2)
 118                 fatal("internal error, bad protocol version %d", version);
 119         return &idtable[version];
 120 }
 121
 122 /* return matching private key for given public key */
 123 static Identity *
 124 lookup_identity(Key *key, int version)
 125 {
 126         Identity *id;
 127
 128         Idtab *tab = idtab_lookup(version);
 129         TAILQ_FOREACH(id, &tab->idlist, next) {
 130                 if (key_equal(key, id->key))
 131                         return (id);
 132         }
 133         return (NULL);
 134 }
 135
 136 static void
 137 free_identity(Identity *id)
 138 {
 139         key_free(id->key);
 140         xfree(id->comment);
 141         xfree(id);
 142 }
 143
 144 /* send list of supported public keys to 'client' */
 145 static void
 146 process_request_identities(SocketEntry *e, int version)
 147 {
 148         Idtab *tab = idtab_lookup(version);
 149         Buffer msg;
 150         Identity *id;
 151
 152         buffer_init(&msg);
 153         buffer_put_char(&msg, (version == 1) ?
 154             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 155         buffer_put_int(&msg, tab->nentries);
 156         TAILQ_FOREACH(id, &tab->idlist, next) {
 157                 if (id->key->type == KEY_RSA1) {
 158                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 159                         buffer_put_bignum(&msg, id->key->rsa->e);
 160                         buffer_put_bignum(&msg, id->key->rsa->n);
 161                 } else {
 162                         u_char *blob;
 163                         u_int blen;
 164                         key_to_blob(id->key, &blob, &blen);
 165                         buffer_put_string(&msg, blob, blen);
 166                         xfree(blob);
 167                 }
 168                 buffer_put_cstring(&msg, id->comment);
 169         }
 170         buffer_put_int(&e->output, buffer_len(&msg));
 171         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 172         buffer_free(&msg);
 173 }
 174
 175 /* ssh1 only */
 176 static void
 177 process_authentication_challenge1(SocketEntry *e)
 178 {
 179         Identity *id;
 180         Key *key;
 181         BIGNUM *challenge;
 182         int i, len;
 183         Buffer msg;
 184         MD5_CTX md;
 185         u_char buf[32], mdbuf[16], session_id[16];
 186         u_int response_type;
 187
 188         buffer_init(&msg);
 189         key = key_new(KEY_RSA1);
 190         if ((challenge = BN_new()) == NULL)
 191                 fatal("process_authentication_challenge1: BN_new failed");
 192
 193         buffer_get_int(&e->input);                              /* ignored */
 194         buffer_get_bignum(&e->input, key->rsa->e);
 195         buffer_get_bignum(&e->input, key->rsa->n);
 196         buffer_get_bignum(&e->input, challenge);
 197
 198         /* Only protocol 1.1 is supported */
 199         if (buffer_len(&e->input) == 0)
 200                 goto failure;
 201         buffer_get(&e->input, session_id, 16);
 202         response_type = buffer_get_int(&e->input);
 203         if (response_type != 1)
 204                 goto failure;
 205
 206         id = lookup_identity(key, 1);
 207         if (id != NULL) {
 208                 Key *private = id->key;
 209                 /* Decrypt the challenge using the private key. */
 210                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 211                         goto failure;
 212
 213                 /* The response is MD5 of decrypted challenge plus session id. */
 214                 len = BN_num_bytes(challenge);
 215                 if (len <= 0 || len > 32) {
 216                         log("process_authentication_challenge: bad challenge length %d", len);
 217                         goto failure;
 218                 }
 219                 memset(buf, 0, 32);
 220                 BN_bn2bin(challenge, buf + 32 - len);
 221                 MD5_Init(&md);
 222                 MD5_Update(&md, buf, 32);
 223                 MD5_Update(&md, session_id, 16);
 224                 MD5_Final(mdbuf, &md);
 225
 226                 /* Send the response. */
 227                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 228                 for (i = 0; i < 16; i++)
 229                         buffer_put_char(&msg, mdbuf[i]);
 230                 goto send;
 231         }
 232
 233 failure:
 234         /* Unknown identity or protocol error.  Send failure. */
 235         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 236 send:
 237         buffer_put_int(&e->output, buffer_len(&msg));
 238         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 239         key_free(key);
 240         BN_clear_free(challenge);
 241         buffer_free(&msg);
 242 }
 243
 244 /* ssh2 only */
 245 static void
 246 process_sign_request2(SocketEntry *e)
 247 {
 248         extern int datafellows;
 249         Key *key;
 250         u_char *blob, *data, *signature = NULL;
 251         u_int blen, dlen, slen = 0;
 252         int flags;
 253         Buffer msg;
 254         int ok = -1;
 255
 256         datafellows = 0;
 257
 258         blob = buffer_get_string(&e->input, &blen);
 259         data = buffer_get_string(&e->input, &dlen);
 260
 261         flags = buffer_get_int(&e->input);
 262         if (flags & SSH_AGENT_OLD_SIGNATURE)
 263                 datafellows = SSH_BUG_SIGBLOB;
 264
 265         key = key_from_blob(blob, blen);
 266         if (key != NULL) {
 267                 Identity *id = lookup_identity(key, 2);
 268                 if (id != NULL)
 269                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 270         }
 271         key_free(key);
 272         buffer_init(&msg);
 273         if (ok == 0) {
 274                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 275                 buffer_put_string(&msg, signature, slen);
 276         } else {
 277                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 278         }
 279         buffer_put_int(&e->output, buffer_len(&msg));
 280         buffer_append(&e->output, buffer_ptr(&msg),
 281             buffer_len(&msg));
 282         buffer_free(&msg);
 283         xfree(data);
 284         xfree(blob);
 285         if (signature != NULL)
 286                 xfree(signature);
 287 }
 288
 289 /* shared */
 290 static void
 291 process_remove_identity(SocketEntry *e, int version)
 292 {
 293         Key *key = NULL;
 294         u_char *blob;
 295         u_int blen;
 296         u_int bits;
 297         int success = 0;
 298
 299         switch (version) {
 300         case 1:
 301                 key = key_new(KEY_RSA1);
 302                 bits = buffer_get_int(&e->input);
 303                 buffer_get_bignum(&e->input, key->rsa->e);
 304                 buffer_get_bignum(&e->input, key->rsa->n);
 305
 306                 if (bits != key_size(key))
 307                         log("Warning: identity keysize mismatch: actual %d, announced %d",
 308                             key_size(key), bits);
 309                 break;
 310         case 2:
 311                 blob = buffer_get_string(&e->input, &blen);
 312                 key = key_from_blob(blob, blen);
 313                 xfree(blob);
 314                 break;
 315         }
 316         if (key != NULL) {
 317                 Identity *id = lookup_identity(key, version);
 318                 if (id != NULL) {
 319                         /*
 320                          * We have this key.  Free the old key.  Since we
 321                          * don\'t want to leave empty slots in the middle of
 322                          * the array, we actually free the key there and move
 323                          * all the entries between the empty slot and the end
 324                          * of the array.
 325                          */
 326                         Idtab *tab = idtab_lookup(version);
 327                         if (tab->nentries < 1)
 328                                 fatal("process_remove_identity: "
 329                                     "internal error: tab->nentries %d",
 330                                     tab->nentries);
 331                         TAILQ_REMOVE(&tab->idlist, id, next);
 332                         free_identity(id);
 333                         tab->nentries--;
 334                         success = 1;
 335                 }
 336                 key_free(key);
 337         }
 338         buffer_put_int(&e->output, 1);
 339         buffer_put_char(&e->output,
 340             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 341 }
 342
 343 static void
 344 process_remove_all_identities(SocketEntry *e, int version)
 345 {
 346         Idtab *tab = idtab_lookup(version);
 347         Identity *id;
 348
 349         /* Loop over all identities and clear the keys. */
 350         for (id = TAILQ_FIRST(&tab->idlist); id;
 351             id = TAILQ_FIRST(&tab->idlist)) {
 352                 TAILQ_REMOVE(&tab->idlist, id, next);
 353                 free_identity(id);
 354         }
 355
 356         /* Mark that there are no identities. */
 357         tab->nentries = 0;
 358
 359         /* Send success. */
 360         buffer_put_int(&e->output, 1);
 361         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 362         return;
 363 }
 364
 365 static void
 366 process_add_identity(SocketEntry *e, int version)
 367 {
 368         Key *k = NULL;
 369         char *type_name;
 370         char *comment;
 371         int type, success = 0;
 372         Idtab *tab = idtab_lookup(version);
 373
 374         switch (version) {
 375         case 1:
 376                 k = key_new_private(KEY_RSA1);
 377                 buffer_get_int(&e->input);                      /* ignored */
 378                 buffer_get_bignum(&e->input, k->rsa->n);
 379                 buffer_get_bignum(&e->input, k->rsa->e);
 380                 buffer_get_bignum(&e->input, k->rsa->d);
 381                 buffer_get_bignum(&e->input, k->rsa->iqmp);
 382
 383                 /* SSH and SSL have p and q swapped */
 384                 buffer_get_bignum(&e->input, k->rsa->q);        /* p */
 385                 buffer_get_bignum(&e->input, k->rsa->p);        /* q */
 386
 387                 /* Generate additional parameters */
 388                 rsa_generate_additional_parameters(k->rsa);
 389                 break;
 390         case 2:
 391                 type_name = buffer_get_string(&e->input, NULL);
 392                 type = key_type_from_name(type_name);
 393                 xfree(type_name);
 394                 switch (type) {
 395                 case KEY_DSA:
 396                         k = key_new_private(type);
 397                         buffer_get_bignum2(&e->input, k->dsa->p);
 398                         buffer_get_bignum2(&e->input, k->dsa->q);
 399                         buffer_get_bignum2(&e->input, k->dsa->g);
 400                         buffer_get_bignum2(&e->input, k->dsa->pub_key);
 401                         buffer_get_bignum2(&e->input, k->dsa->priv_key);
 402                         break;
 403                 case KEY_RSA:
 404                         k = key_new_private(type);
 405                         buffer_get_bignum2(&e->input, k->rsa->n);
 406                         buffer_get_bignum2(&e->input, k->rsa->e);
 407                         buffer_get_bignum2(&e->input, k->rsa->d);
 408                         buffer_get_bignum2(&e->input, k->rsa->iqmp);
 409                         buffer_get_bignum2(&e->input, k->rsa->p);
 410                         buffer_get_bignum2(&e->input, k->rsa->q);
 411
 412                         /* Generate additional parameters */
 413                         rsa_generate_additional_parameters(k->rsa);
 414                         break;
 415                 default:
 416                         buffer_clear(&e->input);
 417                         goto send;
 418                 }
 419                 break;
 420         }
 421         comment = buffer_get_string(&e->input, NULL);
 422         if (k == NULL) {
 423                 xfree(comment);
 424                 goto send;
 425         }
 426         success = 1;
 427         if (lookup_identity(k, version) == NULL) {
 428                 Identity *id = xmalloc(sizeof(Identity));
 429                 id->key = k;
 430                 id->comment = comment;
 431                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 432                 /* Increment the number of identities. */
 433                 tab->nentries++;
 434         } else {
 435                 key_free(k);
 436                 xfree(comment);
 437         }
 438 send:
 439         buffer_put_int(&e->output, 1);
 440         buffer_put_char(&e->output,
 441             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 442 }
 443
 444
 445 #ifdef SMARTCARD
 446 static void
 447 process_add_smartcard_key (SocketEntry *e)
 448 {
 449         Identity *id;
 450         Idtab *tab;
 451         Key **keys, *k;
 452         char *sc_reader_id = NULL, *pin;
 453         int i, version, success = 0;
 454
 455         sc_reader_id = buffer_get_string(&e->input, NULL);
 456         pin = buffer_get_string(&e->input, NULL);
 457         keys = sc_get_keys(sc_reader_id, pin);
 458         xfree(sc_reader_id);
 459         xfree(pin);
 460
 461         if (keys == NULL || keys[0] == NULL) {
 462                 error("sc_get_keys failed");
 463                 goto send;
 464         }
 465         for (i = 0; keys[i] != NULL; i++) {
 466                 k = keys[i];
 467                 version = k->type == KEY_RSA1 ? 1 : 2;
 468                 tab = idtab_lookup(version);
 469                 if (lookup_identity(k, version) == NULL) {
 470                         id = xmalloc(sizeof(Identity));
 471                         id->key = k;
 472                         id->comment = xstrdup("smartcard key");
 473                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 474                         tab->nentries++;
 475                         success = 1;
 476                 } else {
 477                         key_free(k);
 478                 }
 479                 keys[i] = NULL;
 480         }
 481         xfree(keys);
 482 send:
 483         buffer_put_int(&e->output, 1);
 484         buffer_put_char(&e->output,
 485             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 486 }
 487
 488 static void
 489 process_remove_smartcard_key(SocketEntry *e)
 490 {
 491         Identity *id;
 492         Idtab *tab;
 493         Key **keys, *k = NULL;
 494         char *sc_reader_id = NULL, *pin;
 495         int i, version, success = 0;
 496
 497         sc_reader_id = buffer_get_string(&e->input, NULL);
 498         pin = buffer_get_string(&e->input, NULL);
 499         keys = sc_get_keys(sc_reader_id, pin);
 500         xfree(sc_reader_id);
 501         xfree(pin);
 502
 503         if (keys == NULL || keys[0] == NULL) {
 504                 error("sc_get_keys failed");
 505                 goto send;
 506         }
 507         for (i = 0; keys[i] != NULL; i++) {
 508                 k = keys[i];
 509                 version = k->type == KEY_RSA1 ? 1 : 2;
 510                 if ((id = lookup_identity(k, version)) != NULL) {
 511                         tab = idtab_lookup(version);
 512                         TAILQ_REMOVE(&tab->idlist, id, next);
 513                         tab->nentries--;
 514                         free_identity(id);
 515                         success = 1;
 516                 }
 517                 key_free(k);
 518                 keys[i] = NULL;
 519         }
 520         xfree(keys);
 521 send:
 522         buffer_put_int(&e->output, 1);
 523         buffer_put_char(&e->output,
 524             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 525 }
 526 #endif /* SMARTCARD */
 527
 528 /* dispatch incoming messages */
 529
 530 static void
 531 process_message(SocketEntry *e)
 532 {
 533         u_int msg_len;
 534         u_int type;
 535         u_char *cp;
 536         if (buffer_len(&e->input) < 5)
 537                 return;         /* Incomplete message. */
 538         cp = buffer_ptr(&e->input);
 539         msg_len = GET_32BIT(cp);
 540         if (msg_len > 256 * 1024) {
 541                 shutdown(e->fd, SHUT_RDWR);
 542                 close(e->fd);
 543                 e->type = AUTH_UNUSED;
 544                 return;
 545         }
 546         if (buffer_len(&e->input) < msg_len + 4)
 547                 return;
 548         buffer_consume(&e->input, 4);
 549         type = buffer_get_char(&e->input);
 550
 551         debug("type %d", type);
 552         switch (type) {
 553         /* ssh1 */
 554         case SSH_AGENTC_RSA_CHALLENGE:
 555                 process_authentication_challenge1(e);
 556                 break;
 557         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 558                 process_request_identities(e, 1);
 559                 break;
 560         case SSH_AGENTC_ADD_RSA_IDENTITY:
 561                 process_add_identity(e, 1);
 562                 break;
 563         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 564                 process_remove_identity(e, 1);
 565                 break;
 566         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 567                 process_remove_all_identities(e, 1);
 568                 break;
 569         /* ssh2 */
 570         case SSH2_AGENTC_SIGN_REQUEST:
 571                 process_sign_request2(e);
 572                 break;
 573         case SSH2_AGENTC_REQUEST_IDENTITIES:
 574                 process_request_identities(e, 2);
 575                 break;
 576         case SSH2_AGENTC_ADD_IDENTITY:
 577                 process_add_identity(e, 2);
 578                 break;
 579         case SSH2_AGENTC_REMOVE_IDENTITY:
 580                 process_remove_identity(e, 2);
 581                 break;
 582         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 583                 process_remove_all_identities(e, 2);
 584                 break;
 585 #ifdef SMARTCARD
 586         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 587                 process_add_smartcard_key(e);
 588                 break;
 589         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 590                 process_remove_smartcard_key(e);
 591                 break;
 592 #endif /* SMARTCARD */
 593         default:
 594                 /* Unknown message.  Respond with failure. */
 595                 error("Unknown message %d", type);
 596                 buffer_clear(&e->input);
 597                 buffer_put_int(&e->output, 1);
 598                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 599                 break;
 600         }
 601 }
 602
 603 static void
 604 new_socket(sock_type type, int fd)
 605 {
 606         u_int i, old_alloc;
 607         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 608                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 609
 610         if (fd > max_fd)
 611                 max_fd = fd;
 612
 613         for (i = 0; i < sockets_alloc; i++)
 614                 if (sockets[i].type == AUTH_UNUSED) {
 615                         sockets[i].fd = fd;
 616                         sockets[i].type = type;
 617                         buffer_init(&sockets[i].input);
 618                         buffer_init(&sockets[i].output);
 619                         return;
 620                 }
 621         old_alloc = sockets_alloc;
 622         sockets_alloc += 10;
 623         if (sockets)
 624                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 625         else
 626                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 627         for (i = old_alloc; i < sockets_alloc; i++)
 628                 sockets[i].type = AUTH_UNUSED;
 629         sockets[old_alloc].type = type;
 630         sockets[old_alloc].fd = fd;
 631         buffer_init(&sockets[old_alloc].input);
 632         buffer_init(&sockets[old_alloc].output);
 633 }
 634
 635 static int
 636 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 637 {
 638         u_int i, sz;
 639         int n = 0;
 640
 641         for (i = 0; i < sockets_alloc; i++) {
 642                 switch (sockets[i].type) {
 643                 case AUTH_SOCKET:
 644                 case AUTH_CONNECTION:
 645                         n = MAX(n, sockets[i].fd);
 646                         break;
 647                 case AUTH_UNUSED:
 648                         break;
 649                 default:
 650                         fatal("Unknown socket type %d", sockets[i].type);
 651                         break;
 652                 }
 653         }
 654
 655         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 656         if (*fdrp == NULL || sz > *nallocp) {
 657                 if (*fdrp)
 658                         xfree(*fdrp);
 659                 if (*fdwp)
 660                         xfree(*fdwp);
 661                 *fdrp = xmalloc(sz);
 662                 *fdwp = xmalloc(sz);
 663                 *nallocp = sz;
 664         }
 665         if (n < *fdl)
 666                 debug("XXX shrink: %d < %d", n, *fdl);
 667         *fdl = n;
 668         memset(*fdrp, 0, sz);
 669         memset(*fdwp, 0, sz);
 670
 671         for (i = 0; i < sockets_alloc; i++) {
 672                 switch (sockets[i].type) {
 673                 case AUTH_SOCKET:
 674                 case AUTH_CONNECTION:
 675                         FD_SET(sockets[i].fd, *fdrp);
 676                         if (buffer_len(&sockets[i].output) > 0)
 677                                 FD_SET(sockets[i].fd, *fdwp);
 678                         break;
 679                 default:
 680                         break;
 681                 }
 682         }
 683         return (1);
 684 }
 685
 686 static void
 687 after_select(fd_set *readset, fd_set *writeset)
 688 {
 689         u_int i;
 690         int len, sock;
 691         socklen_t slen;
 692         char buf[1024];
 693         struct sockaddr_un sunaddr;
 694
 695         for (i = 0; i < sockets_alloc; i++)
 696                 switch (sockets[i].type) {
 697                 case AUTH_UNUSED:
 698                         break;
 699                 case AUTH_SOCKET:
 700                         if (FD_ISSET(sockets[i].fd, readset)) {
 701                                 slen = sizeof(sunaddr);
 702                                 sock = accept(sockets[i].fd,
 703                                     (struct sockaddr *) &sunaddr, &slen);
 704                                 if (sock < 0) {
 705                                         error("accept from AUTH_SOCKET: %s",
 706                                             strerror(errno));
 707                                         break;
 708                                 }
 709                                 new_socket(AUTH_CONNECTION, sock);
 710                         }
 711                         break;
 712                 case AUTH_CONNECTION:
 713                         if (buffer_len(&sockets[i].output) > 0 &&
 714                             FD_ISSET(sockets[i].fd, writeset)) {
 715                                 do {
 716                                         len = write(sockets[i].fd,
 717                                             buffer_ptr(&sockets[i].output),
 718                                             buffer_len(&sockets[i].output));
 719                                         if (len == -1 && (errno == EAGAIN ||
 720                                             errno == EINTR))
 721                                                 continue;
 722                                         break;
 723                                 } while (1);
 724                                 if (len <= 0) {
 725                                         shutdown(sockets[i].fd, SHUT_RDWR);
 726                                         close(sockets[i].fd);
 727                                         sockets[i].type = AUTH_UNUSED;
 728                                         buffer_free(&sockets[i].input);
 729                                         buffer_free(&sockets[i].output);
 730                                         break;
 731                                 }
 732                                 buffer_consume(&sockets[i].output, len);
 733                         }
 734                         if (FD_ISSET(sockets[i].fd, readset)) {
 735                                 do {
 736                                         len = read(sockets[i].fd, buf, sizeof(buf));
 737                                         if (len == -1 && (errno == EAGAIN ||
 738                                             errno == EINTR))
 739                                                 continue;
 740                                         break;
 741                                 } while (1);
 742                                 if (len <= 0) {
 743                                         shutdown(sockets[i].fd, SHUT_RDWR);
 744                                         close(sockets[i].fd);
 745                                         sockets[i].type = AUTH_UNUSED;
 746                                         buffer_free(&sockets[i].input);
 747                                         buffer_free(&sockets[i].output);
 748                                         break;
 749                                 }
 750                                 buffer_append(&sockets[i].input, buf, len);
 751                                 process_message(&sockets[i]);
 752                         }
 753                         break;
 754                 default:
 755                         fatal("Unknown type %d", sockets[i].type);
 756                 }
 757 }
 758
 759 static void
 760 cleanup_socket(void *p)
 761 {
 762         if (socket_name[0])
 763                 unlink(socket_name);
 764         if (socket_dir[0])
 765                 rmdir(socket_dir);
 766 }
 767
 768 static void
 769 cleanup_exit(int i)
 770 {
 771         cleanup_socket(NULL);
 772         exit(i);
 773 }
 774
 775 static void
 776 cleanup_handler(int sig)
 777 {
 778         cleanup_socket(NULL);
 779         _exit(2);
 780 }
 781
 782 static void
 783 check_parent_exists(int sig)
 784 {
 785         int save_errno = errno;
 786
 787         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 788                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 789                 cleanup_handler(sig); /* safe */
 790         }
 791         signal(SIGALRM, check_parent_exists);
 792         alarm(10);
 793         errno = save_errno;
 794 }
 795
 796 static void
 797 usage(void)
 798 {
 799         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 800             __progname);
 801         fprintf(stderr, "Options:\n");
 802         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 803         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 804         fprintf(stderr, "  -k          Kill the current agent.\n");
 805         fprintf(stderr, "  -d          Debug mode.\n");
 806         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 807         exit(1);
 808 }
 809
 810 int
 811 main(int ac, char **av)
 812 {
 813         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 814         struct sockaddr_un sunaddr;
 815 #ifdef HAVE_SETRLIMIT
 816         struct rlimit rlim;
 817 #endif
 818 #ifdef HAVE_CYGWIN
 819         int prev_mask;
 820 #endif
 821         pid_t pid;
 822         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 823         char *agentsocket = NULL;
 824         extern int optind;
 825         fd_set *readsetp = NULL, *writesetp = NULL;
 826
 827         SSLeay_add_all_algorithms();
 828
 829         __progname = get_progname(av[0]);
 830         init_rng();
 831         seed_rng();
 832
 833 #ifdef __GNU_LIBRARY__
 834         while ((ch = getopt(ac, av, "+cdksa:")) != -1) {
 835 #else /* __GNU_LIBRARY__ */
 836         while ((ch = getopt(ac, av, "cdksa:")) != -1) {
 837 #endif /* __GNU_LIBRARY__ */
 838                 switch (ch) {
 839                 case 'c':
 840                         if (s_flag)
 841                                 usage();
 842                         c_flag++;
 843                         break;
 844                 case 'k':
 845                         k_flag++;
 846                         break;
 847                 case 's':
 848                         if (c_flag)
 849                                 usage();
 850                         s_flag++;
 851                         break;
 852                 case 'd':
 853                         if (d_flag)
 854                                 usage();
 855                         d_flag++;
 856                         break;
 857                 case 'a':
 858                         agentsocket = optarg;
 859                         break;
 860                 default:
 861                         usage();
 862                 }
 863         }
 864         ac -= optind;
 865         av += optind;
 866
 867         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
 868                 usage();
 869
 870         if (ac == 0 && !c_flag && !s_flag) {
 871                 shell = getenv("SHELL");
 872                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 873                         c_flag = 1;
 874         }
 875         if (k_flag) {
 876                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 877                 if (pidstr == NULL) {
 878                         fprintf(stderr, "%s not set, cannot kill agent\n",
 879                             SSH_AGENTPID_ENV_NAME);
 880                         exit(1);
 881                 }
 882                 pid = atoi(pidstr);
 883                 if (pid < 1) {
 884                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 885                             SSH_AGENTPID_ENV_NAME, pidstr);
 886                         exit(1);
 887                 }
 888                 if (kill(pid, SIGTERM) == -1) {
 889                         perror("kill");
 890                         exit(1);
 891                 }
 892                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 893                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 894                 printf(format, SSH_AGENTPID_ENV_NAME);
 895                 printf("echo Agent pid %d killed;\n", pid);
 896                 exit(0);
 897         }
 898         parent_pid = getpid();
 899
 900         if (agentsocket == NULL) {
 901                 /* Create private directory for agent socket */
 902                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 903                 if (mkdtemp(socket_dir) == NULL) {
 904                         perror("mkdtemp: private socket dir");
 905                         exit(1);
 906                 }
 907                 snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 908                     parent_pid);
 909         } else {
 910                 /* Try to use specified agent socket */
 911                 socket_dir[0] = '\0';
 912                 strlcpy(socket_name, agentsocket, sizeof socket_name);
 913         }
 914
 915         /*
 916          * Create socket early so it will exist before command gets run from
 917          * the parent.
 918          */
 919         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 920         if (sock < 0) {
 921                 perror("socket");
 922                 cleanup_exit(1);
 923         }
 924         memset(&sunaddr, 0, sizeof(sunaddr));
 925         sunaddr.sun_family = AF_UNIX;
 926         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 927 #ifdef HAVE_CYGWIN
 928         prev_mask = umask(0177);
 929 #endif
 930         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 931                 perror("bind");
 932 #ifdef HAVE_CYGWIN
 933                 umask(prev_mask);
 934 #endif
 935                 cleanup_exit(1);
 936         }
 937 #ifdef HAVE_CYGWIN
 938         umask(prev_mask);
 939 #endif
 940         if (listen(sock, 5) < 0) {
 941                 perror("listen");
 942                 cleanup_exit(1);
 943         }
 944
 945         /*
 946          * Fork, and have the parent execute the command, if any, or present
 947          * the socket data.  The child continues as the authentication agent.
 948          */
 949         if (d_flag) {
 950                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
 951                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 952                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 953                     SSH_AUTHSOCKET_ENV_NAME);
 954                 printf("echo Agent pid %d;\n", parent_pid);
 955                 goto skip;
 956         }
 957         pid = fork();
 958         if (pid == -1) {
 959                 perror("fork");
 960                 cleanup_exit(1);
 961         }
 962         if (pid != 0) {         /* Parent - execute the given command. */
 963                 close(sock);
 964                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 965                 if (ac == 0) {
 966                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 967                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 968                             SSH_AUTHSOCKET_ENV_NAME);
 969                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 970                             SSH_AGENTPID_ENV_NAME);
 971                         printf("echo Agent pid %d;\n", pid);
 972                         exit(0);
 973                 }
 974                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 975                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 976                         perror("setenv");
 977                         exit(1);
 978                 }
 979                 execvp(av[0], av);
 980                 perror(av[0]);
 981                 exit(1);
 982         }
 983         /* child */
 984         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
 985
 986         if (setsid() == -1) {
 987                 error("setsid: %s", strerror(errno));
 988                 cleanup_exit(1);
 989         }
 990
 991         (void)chdir("/");
 992         close(0);
 993         close(1);
 994         close(2);
 995
 996 #ifdef HAVE_SETRLIMIT
 997         /* deny core dumps, since memory contains unencrypted private keys */
 998         rlim.rlim_cur = rlim.rlim_max = 0;
 999         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1000                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1001                 cleanup_exit(1);
1002         }
1003 #endif
1004
1005 skip:
1006         fatal_add_cleanup(cleanup_socket, NULL);
1007         new_socket(AUTH_SOCKET, sock);
1008         if (ac > 0) {
1009                 signal(SIGALRM, check_parent_exists);
1010                 alarm(10);
1011         }
1012         idtab_init();
1013         if (!d_flag)
1014                 signal(SIGINT, SIG_IGN);
1015         signal(SIGPIPE, SIG_IGN);
1016         signal(SIGHUP, cleanup_handler);
1017         signal(SIGTERM, cleanup_handler);
1018         nalloc = 0;
1019
1020         while (1) {
1021                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1022                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1023                         if (errno == EINTR)
1024                                 continue;
1025                         fatal("select: %s", strerror(errno));
1026                 }
1027                 after_select(readsetp, writesetp);
1028         }
1029         /* NOTREACHED */
1030 }