ssh-agent.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * The authentication agent program.
   6  *
   7  * As far as I am concerned, the code I have written for this software
   8  * can be used freely for any purpose.  Any derived versions of this
   9  * software must be clearly marked as such, and if the derived work is
  10  * incompatible with the protocol description in the RFC file, it must be
  11  * called by a name other than "ssh" or "Secure Shell".
  12  *
  13  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  14  *
  15  * Redistribution and use in source and binary forms, with or without
  16  * modification, are permitted provided that the following conditions
  17  * are met:
  18  * 1. Redistributions of source code must retain the above copyright
  19  *    notice, this list of conditions and the following disclaimer.
  20  * 2. Redistributions in binary form must reproduce the above copyright
  21  *    notice, this list of conditions and the following disclaimer in the
  22  *    documentation and/or other materials provided with the distribution.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  27  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  28  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  29  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  30  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  31  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  32  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  33  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 #include "includes.h"
  37 RCSID("$OpenBSD: ssh-agent.c,v 1.85 2002/04/02 11:49:39 markus Exp $");
  38
  39 #if defined(HAVE_SYS_QUEUE_H) && !defined(HAVE_BOGUS_SYS_QUEUE_H)
  40 #include <sys/queue.h>
  41 #else
  42 #include "openbsd-compat/fake-queue.h"
  43 #endif
  44
  45 #include <openssl/evp.h>
  46 #include <openssl/md5.h>
  47
  48 #include "ssh.h"
  49 #include "rsa.h"
  50 #include "buffer.h"
  51 #include "bufaux.h"
  52 #include "xmalloc.h"
  53 #include "getput.h"
  54 #include "key.h"
  55 #include "authfd.h"
  56 #include "compat.h"
  57 #include "log.h"
  58
  59 #ifdef SMARTCARD
  60 #include "scard.h"
  61 #endif
  62
  63 typedef enum {
  64         AUTH_UNUSED,
  65         AUTH_SOCKET,
  66         AUTH_CONNECTION
  67 } sock_type;
  68
  69 typedef struct {
  70         int fd;
  71         sock_type type;
  72         Buffer input;
  73         Buffer output;
  74 } SocketEntry;
  75
  76 u_int sockets_alloc = 0;
  77 SocketEntry *sockets = NULL;
  78
  79 typedef struct identity {
  80         TAILQ_ENTRY(identity) next;
  81         Key *key;
  82         char *comment;
  83 } Identity;
  84
  85 typedef struct {
  86         int nentries;
  87         TAILQ_HEAD(idqueue, identity) idlist;
  88 } Idtab;
  89
  90 /* private key table, one per protocol version */
  91 Idtab idtable[3];
  92
  93 int max_fd = 0;
  94
  95 /* pid of shell == parent of agent */
  96 pid_t parent_pid = -1;
  97
  98 /* pathname and directory for AUTH_SOCKET */
  99 char socket_name[1024];
 100 char socket_dir[1024];
 101
 102 #ifdef HAVE___PROGNAME
 103 extern char *__progname;
 104 #else
 105 char *__progname;
 106 #endif
 107
 108 static void
 109 idtab_init(void)
 110 {
 111         int i;
 112         for (i = 0; i <=2; i++) {
 113                 TAILQ_INIT(&idtable[i].idlist);
 114                 idtable[i].nentries = 0;
 115         }
 116 }
 117
 118 /* return private key table for requested protocol version */
 119 static Idtab *
 120 idtab_lookup(int version)
 121 {
 122         if (version < 1 || version > 2)
 123                 fatal("internal error, bad protocol version %d", version);
 124         return &idtable[version];
 125 }
 126
 127 /* return matching private key for given public key */
 128 static Identity *
 129 lookup_identity(Key *key, int version)
 130 {
 131         Identity *id;
 132
 133         Idtab *tab = idtab_lookup(version);
 134         TAILQ_FOREACH(id, &tab->idlist, next) {
 135                 if (key_equal(key, id->key))
 136                         return (id);
 137         }
 138         return (NULL);
 139 }
 140
 141 static void
 142 free_identity(Identity *id)
 143 {
 144         key_free(id->key);
 145         xfree(id->comment);
 146         xfree(id);
 147 }
 148
 149 /* send list of supported public keys to 'client' */
 150 static void
 151 process_request_identities(SocketEntry *e, int version)
 152 {
 153         Idtab *tab = idtab_lookup(version);
 154         Buffer msg;
 155         Identity *id;
 156
 157         buffer_init(&msg);
 158         buffer_put_char(&msg, (version == 1) ?
 159             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 160         buffer_put_int(&msg, tab->nentries);
 161         TAILQ_FOREACH(id, &tab->idlist, next) {
 162                 if (id->key->type == KEY_RSA1) {
 163                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 164                         buffer_put_bignum(&msg, id->key->rsa->e);
 165                         buffer_put_bignum(&msg, id->key->rsa->n);
 166                 } else {
 167                         u_char *blob;
 168                         u_int blen;
 169                         key_to_blob(id->key, &blob, &blen);
 170                         buffer_put_string(&msg, blob, blen);
 171                         xfree(blob);
 172                 }
 173                 buffer_put_cstring(&msg, id->comment);
 174         }
 175         buffer_put_int(&e->output, buffer_len(&msg));
 176         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 177         buffer_free(&msg);
 178 }
 179
 180 /* ssh1 only */
 181 static void
 182 process_authentication_challenge1(SocketEntry *e)
 183 {
 184         Identity *id;
 185         Key *key;
 186         BIGNUM *challenge;
 187         int i, len;
 188         Buffer msg;
 189         MD5_CTX md;
 190         u_char buf[32], mdbuf[16], session_id[16];
 191         u_int response_type;
 192
 193         buffer_init(&msg);
 194         key = key_new(KEY_RSA1);
 195         if ((challenge = BN_new()) == NULL)
 196                 fatal("process_authentication_challenge1: BN_new failed");
 197
 198         buffer_get_int(&e->input);                              /* ignored */
 199         buffer_get_bignum(&e->input, key->rsa->e);
 200         buffer_get_bignum(&e->input, key->rsa->n);
 201         buffer_get_bignum(&e->input, challenge);
 202
 203         /* Only protocol 1.1 is supported */
 204         if (buffer_len(&e->input) == 0)
 205                 goto failure;
 206         buffer_get(&e->input, session_id, 16);
 207         response_type = buffer_get_int(&e->input);
 208         if (response_type != 1)
 209                 goto failure;
 210
 211         id = lookup_identity(key, 1);
 212         if (id != NULL) {
 213                 Key *private = id->key;
 214                 /* Decrypt the challenge using the private key. */
 215                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 216                         goto failure;
 217
 218                 /* The response is MD5 of decrypted challenge plus session id. */
 219                 len = BN_num_bytes(challenge);
 220                 if (len <= 0 || len > 32) {
 221                         log("process_authentication_challenge: bad challenge length %d", len);
 222                         goto failure;
 223                 }
 224                 memset(buf, 0, 32);
 225                 BN_bn2bin(challenge, buf + 32 - len);
 226                 MD5_Init(&md);
 227                 MD5_Update(&md, buf, 32);
 228                 MD5_Update(&md, session_id, 16);
 229                 MD5_Final(mdbuf, &md);
 230
 231                 /* Send the response. */
 232                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 233                 for (i = 0; i < 16; i++)
 234                         buffer_put_char(&msg, mdbuf[i]);
 235                 goto send;
 236         }
 237
 238 failure:
 239         /* Unknown identity or protocol error.  Send failure. */
 240         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 241 send:
 242         buffer_put_int(&e->output, buffer_len(&msg));
 243         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 244         key_free(key);
 245         BN_clear_free(challenge);
 246         buffer_free(&msg);
 247 }
 248
 249 /* ssh2 only */
 250 static void
 251 process_sign_request2(SocketEntry *e)
 252 {
 253         extern int datafellows;
 254         Key *key;
 255         u_char *blob, *data, *signature = NULL;
 256         u_int blen, dlen, slen = 0;
 257         int flags;
 258         Buffer msg;
 259         int ok = -1;
 260
 261         datafellows = 0;
 262
 263         blob = buffer_get_string(&e->input, &blen);
 264         data = buffer_get_string(&e->input, &dlen);
 265
 266         flags = buffer_get_int(&e->input);
 267         if (flags & SSH_AGENT_OLD_SIGNATURE)
 268                 datafellows = SSH_BUG_SIGBLOB;
 269
 270         key = key_from_blob(blob, blen);
 271         if (key != NULL) {
 272                 Identity *id = lookup_identity(key, 2);
 273                 if (id != NULL)
 274                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 275         }
 276         key_free(key);
 277         buffer_init(&msg);
 278         if (ok == 0) {
 279                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 280                 buffer_put_string(&msg, signature, slen);
 281         } else {
 282                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 283         }
 284         buffer_put_int(&e->output, buffer_len(&msg));
 285         buffer_append(&e->output, buffer_ptr(&msg),
 286             buffer_len(&msg));
 287         buffer_free(&msg);
 288         xfree(data);
 289         xfree(blob);
 290         if (signature != NULL)
 291                 xfree(signature);
 292 }
 293
 294 /* shared */
 295 static void
 296 process_remove_identity(SocketEntry *e, int version)
 297 {
 298         Key *key = NULL;
 299         u_char *blob;
 300         u_int blen;
 301         u_int bits;
 302         int success = 0;
 303
 304         switch (version) {
 305         case 1:
 306                 key = key_new(KEY_RSA1);
 307                 bits = buffer_get_int(&e->input);
 308                 buffer_get_bignum(&e->input, key->rsa->e);
 309                 buffer_get_bignum(&e->input, key->rsa->n);
 310
 311                 if (bits != key_size(key))
 312                         log("Warning: identity keysize mismatch: actual %d, announced %d",
 313                             key_size(key), bits);
 314                 break;
 315         case 2:
 316                 blob = buffer_get_string(&e->input, &blen);
 317                 key = key_from_blob(blob, blen);
 318                 xfree(blob);
 319                 break;
 320         }
 321         if (key != NULL) {
 322                 Identity *id = lookup_identity(key, version);
 323                 if (id != NULL) {
 324                         /*
 325                          * We have this key.  Free the old key.  Since we
 326                          * don\'t want to leave empty slots in the middle of
 327                          * the array, we actually free the key there and move
 328                          * all the entries between the empty slot and the end
 329                          * of the array.
 330                          */
 331                         Idtab *tab = idtab_lookup(version);
 332                         if (tab->nentries < 1)
 333                                 fatal("process_remove_identity: "
 334                                     "internal error: tab->nentries %d",
 335                                     tab->nentries);
 336                         TAILQ_REMOVE(&tab->idlist, id, next);
 337                         free_identity(id);
 338                         tab->nentries--;
 339                         success = 1;
 340                 }
 341                 key_free(key);
 342         }
 343         buffer_put_int(&e->output, 1);
 344         buffer_put_char(&e->output,
 345             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 346 }
 347
 348 static void
 349 process_remove_all_identities(SocketEntry *e, int version)
 350 {
 351         Idtab *tab = idtab_lookup(version);
 352         Identity *id;
 353
 354         /* Loop over all identities and clear the keys. */
 355         for (id = TAILQ_FIRST(&tab->idlist); id;
 356             id = TAILQ_FIRST(&tab->idlist)) {
 357                 TAILQ_REMOVE(&tab->idlist, id, next);
 358                 free_identity(id);
 359         }
 360
 361         /* Mark that there are no identities. */
 362         tab->nentries = 0;
 363
 364         /* Send success. */
 365         buffer_put_int(&e->output, 1);
 366         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 367         return;
 368 }
 369
 370 static void
 371 process_add_identity(SocketEntry *e, int version)
 372 {
 373         Key *k = NULL;
 374         char *type_name;
 375         char *comment;
 376         int type, success = 0;
 377         Idtab *tab = idtab_lookup(version);
 378
 379         switch (version) {
 380         case 1:
 381                 k = key_new_private(KEY_RSA1);
 382                 buffer_get_int(&e->input);                      /* ignored */
 383                 buffer_get_bignum(&e->input, k->rsa->n);
 384                 buffer_get_bignum(&e->input, k->rsa->e);
 385                 buffer_get_bignum(&e->input, k->rsa->d);
 386                 buffer_get_bignum(&e->input, k->rsa->iqmp);
 387
 388                 /* SSH and SSL have p and q swapped */
 389                 buffer_get_bignum(&e->input, k->rsa->q);        /* p */
 390                 buffer_get_bignum(&e->input, k->rsa->p);        /* q */
 391
 392                 /* Generate additional parameters */
 393                 rsa_generate_additional_parameters(k->rsa);
 394                 break;
 395         case 2:
 396                 type_name = buffer_get_string(&e->input, NULL);
 397                 type = key_type_from_name(type_name);
 398                 xfree(type_name);
 399                 switch (type) {
 400                 case KEY_DSA:
 401                         k = key_new_private(type);
 402                         buffer_get_bignum2(&e->input, k->dsa->p);
 403                         buffer_get_bignum2(&e->input, k->dsa->q);
 404                         buffer_get_bignum2(&e->input, k->dsa->g);
 405                         buffer_get_bignum2(&e->input, k->dsa->pub_key);
 406                         buffer_get_bignum2(&e->input, k->dsa->priv_key);
 407                         break;
 408                 case KEY_RSA:
 409                         k = key_new_private(type);
 410                         buffer_get_bignum2(&e->input, k->rsa->n);
 411                         buffer_get_bignum2(&e->input, k->rsa->e);
 412                         buffer_get_bignum2(&e->input, k->rsa->d);
 413                         buffer_get_bignum2(&e->input, k->rsa->iqmp);
 414                         buffer_get_bignum2(&e->input, k->rsa->p);
 415                         buffer_get_bignum2(&e->input, k->rsa->q);
 416
 417                         /* Generate additional parameters */
 418                         rsa_generate_additional_parameters(k->rsa);
 419                         break;
 420                 default:
 421                         buffer_clear(&e->input);
 422                         goto send;
 423                 }
 424                 break;
 425         }
 426         comment = buffer_get_string(&e->input, NULL);
 427         if (k == NULL) {
 428                 xfree(comment);
 429                 goto send;
 430         }
 431         success = 1;
 432         if (lookup_identity(k, version) == NULL) {
 433                 Identity *id = xmalloc(sizeof(Identity));
 434                 id->key = k;
 435                 id->comment = comment;
 436                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 437                 /* Increment the number of identities. */
 438                 tab->nentries++;
 439         } else {
 440                 key_free(k);
 441                 xfree(comment);
 442         }
 443 send:
 444         buffer_put_int(&e->output, 1);
 445         buffer_put_char(&e->output,
 446             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 447 }
 448
 449
 450 #ifdef SMARTCARD
 451 static void
 452 process_add_smartcard_key (SocketEntry *e)
 453 {
 454         Identity *id;
 455         Idtab *tab;
 456         Key **keys, *k;
 457         char *sc_reader_id = NULL, *pin;
 458         int i, version, success = 0;
 459
 460         sc_reader_id = buffer_get_string(&e->input, NULL);
 461         pin = buffer_get_string(&e->input, NULL);
 462         keys = sc_get_keys(sc_reader_id, pin);
 463         xfree(sc_reader_id);
 464         xfree(pin);
 465
 466         if (keys == NULL || keys[0] == NULL) {
 467                 error("sc_get_keys failed");
 468                 goto send;
 469         }
 470         for (i = 0; keys[i] != NULL; i++) {
 471                 k = keys[i];
 472                 version = k->type == KEY_RSA1 ? 1 : 2;
 473                 tab = idtab_lookup(version);
 474                 if (lookup_identity(k, version) == NULL) {
 475                         id = xmalloc(sizeof(Identity));
 476                         id->key = k;
 477                         id->comment = xstrdup("smartcard key");
 478                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 479                         tab->nentries++;
 480                         success = 1;
 481                 } else {
 482                         key_free(k);
 483                 }
 484                 keys[i] = NULL;
 485         }
 486         xfree(keys);
 487 send:
 488         buffer_put_int(&e->output, 1);
 489         buffer_put_char(&e->output,
 490             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 491 }
 492
 493 static void
 494 process_remove_smartcard_key(SocketEntry *e)
 495 {
 496         Identity *id;
 497         Idtab *tab;
 498         Key **keys, *k = NULL;
 499         char *sc_reader_id = NULL, *pin;
 500         int i, version, success = 0;
 501
 502         sc_reader_id = buffer_get_string(&e->input, NULL);
 503         pin = buffer_get_string(&e->input, NULL);
 504         keys = sc_get_keys(sc_reader_id, pin);
 505         xfree(sc_reader_id);
 506         xfree(pin);
 507
 508         if (keys == NULL || keys[0] == NULL) {
 509                 error("sc_get_keys failed");
 510                 goto send;
 511         }
 512         for (i = 0; keys[i] != NULL; i++) {
 513                 k = keys[i];
 514                 version = k->type == KEY_RSA1 ? 1 : 2;
 515                 if ((id = lookup_identity(k, version)) != NULL) {
 516                         tab = idtab_lookup(version);
 517                         TAILQ_REMOVE(&tab->idlist, id, next);
 518                         tab->nentries--;
 519                         free_identity(id);
 520                         success = 1;
 521                 }
 522                 key_free(k);
 523                 keys[i] = NULL;
 524         }
 525         xfree(keys);
 526 send:
 527         buffer_put_int(&e->output, 1);
 528         buffer_put_char(&e->output,
 529             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 530 }
 531 #endif /* SMARTCARD */
 532
 533 /* dispatch incoming messages */
 534
 535 static void
 536 process_message(SocketEntry *e)
 537 {
 538         u_int msg_len;
 539         u_int type;
 540         u_char *cp;
 541         if (buffer_len(&e->input) < 5)
 542                 return;         /* Incomplete message. */
 543         cp = buffer_ptr(&e->input);
 544         msg_len = GET_32BIT(cp);
 545         if (msg_len > 256 * 1024) {
 546                 shutdown(e->fd, SHUT_RDWR);
 547                 close(e->fd);
 548                 e->type = AUTH_UNUSED;
 549                 return;
 550         }
 551         if (buffer_len(&e->input) < msg_len + 4)
 552                 return;
 553         buffer_consume(&e->input, 4);
 554         type = buffer_get_char(&e->input);
 555
 556         debug("type %d", type);
 557         switch (type) {
 558         /* ssh1 */
 559         case SSH_AGENTC_RSA_CHALLENGE:
 560                 process_authentication_challenge1(e);
 561                 break;
 562         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 563                 process_request_identities(e, 1);
 564                 break;
 565         case SSH_AGENTC_ADD_RSA_IDENTITY:
 566                 process_add_identity(e, 1);
 567                 break;
 568         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 569                 process_remove_identity(e, 1);
 570                 break;
 571         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 572                 process_remove_all_identities(e, 1);
 573                 break;
 574         /* ssh2 */
 575         case SSH2_AGENTC_SIGN_REQUEST:
 576                 process_sign_request2(e);
 577                 break;
 578         case SSH2_AGENTC_REQUEST_IDENTITIES:
 579                 process_request_identities(e, 2);
 580                 break;
 581         case SSH2_AGENTC_ADD_IDENTITY:
 582                 process_add_identity(e, 2);
 583                 break;
 584         case SSH2_AGENTC_REMOVE_IDENTITY:
 585                 process_remove_identity(e, 2);
 586                 break;
 587         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 588                 process_remove_all_identities(e, 2);
 589                 break;
 590 #ifdef SMARTCARD
 591         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 592                 process_add_smartcard_key(e);
 593                 break;
 594         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 595                 process_remove_smartcard_key(e);
 596                 break;
 597 #endif /* SMARTCARD */
 598         default:
 599                 /* Unknown message.  Respond with failure. */
 600                 error("Unknown message %d", type);
 601                 buffer_clear(&e->input);
 602                 buffer_put_int(&e->output, 1);
 603                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 604                 break;
 605         }
 606 }
 607
 608 static void
 609 new_socket(sock_type type, int fd)
 610 {
 611         u_int i, old_alloc;
 612         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 613                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 614
 615         if (fd > max_fd)
 616                 max_fd = fd;
 617
 618         for (i = 0; i < sockets_alloc; i++)
 619                 if (sockets[i].type == AUTH_UNUSED) {
 620                         sockets[i].fd = fd;
 621                         sockets[i].type = type;
 622                         buffer_init(&sockets[i].input);
 623                         buffer_init(&sockets[i].output);
 624                         return;
 625                 }
 626         old_alloc = sockets_alloc;
 627         sockets_alloc += 10;
 628         if (sockets)
 629                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 630         else
 631                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 632         for (i = old_alloc; i < sockets_alloc; i++)
 633                 sockets[i].type = AUTH_UNUSED;
 634         sockets[old_alloc].type = type;
 635         sockets[old_alloc].fd = fd;
 636         buffer_init(&sockets[old_alloc].input);
 637         buffer_init(&sockets[old_alloc].output);
 638 }
 639
 640 static int
 641 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 642 {
 643         u_int i, sz;
 644         int n = 0;
 645
 646         for (i = 0; i < sockets_alloc; i++) {
 647                 switch (sockets[i].type) {
 648                 case AUTH_SOCKET:
 649                 case AUTH_CONNECTION:
 650                         n = MAX(n, sockets[i].fd);
 651                         break;
 652                 case AUTH_UNUSED:
 653                         break;
 654                 default:
 655                         fatal("Unknown socket type %d", sockets[i].type);
 656                         break;
 657                 }
 658         }
 659
 660         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 661         if (*fdrp == NULL || sz > *nallocp) {
 662                 if (*fdrp)
 663                         xfree(*fdrp);
 664                 if (*fdwp)
 665                         xfree(*fdwp);
 666                 *fdrp = xmalloc(sz);
 667                 *fdwp = xmalloc(sz);
 668                 *nallocp = sz;
 669         }
 670         if (n < *fdl)
 671                 debug("XXX shrink: %d < %d", n, *fdl);
 672         *fdl = n;
 673         memset(*fdrp, 0, sz);
 674         memset(*fdwp, 0, sz);
 675
 676         for (i = 0; i < sockets_alloc; i++) {
 677                 switch (sockets[i].type) {
 678                 case AUTH_SOCKET:
 679                 case AUTH_CONNECTION:
 680                         FD_SET(sockets[i].fd, *fdrp);
 681                         if (buffer_len(&sockets[i].output) > 0)
 682                                 FD_SET(sockets[i].fd, *fdwp);
 683                         break;
 684                 default:
 685                         break;
 686                 }
 687         }
 688         return (1);
 689 }
 690
 691 static void
 692 after_select(fd_set *readset, fd_set *writeset)
 693 {
 694         u_int i;
 695         int len, sock;
 696         socklen_t slen;
 697         char buf[1024];
 698         struct sockaddr_un sunaddr;
 699
 700         for (i = 0; i < sockets_alloc; i++)
 701                 switch (sockets[i].type) {
 702                 case AUTH_UNUSED:
 703                         break;
 704                 case AUTH_SOCKET:
 705                         if (FD_ISSET(sockets[i].fd, readset)) {
 706                                 slen = sizeof(sunaddr);
 707                                 sock = accept(sockets[i].fd,
 708                                     (struct sockaddr *) &sunaddr, &slen);
 709                                 if (sock < 0) {
 710                                         error("accept from AUTH_SOCKET: %s",
 711                                             strerror(errno));
 712                                         break;
 713                                 }
 714                                 new_socket(AUTH_CONNECTION, sock);
 715                         }
 716                         break;
 717                 case AUTH_CONNECTION:
 718                         if (buffer_len(&sockets[i].output) > 0 &&
 719                             FD_ISSET(sockets[i].fd, writeset)) {
 720                                 do {
 721                                         len = write(sockets[i].fd,
 722                                             buffer_ptr(&sockets[i].output),
 723                                             buffer_len(&sockets[i].output));
 724                                         if (len == -1 && (errno == EAGAIN ||
 725                                             errno == EINTR))
 726                                                 continue;
 727                                         break;
 728                                 } while (1);
 729                                 if (len <= 0) {
 730                                         shutdown(sockets[i].fd, SHUT_RDWR);
 731                                         close(sockets[i].fd);
 732                                         sockets[i].type = AUTH_UNUSED;
 733                                         buffer_free(&sockets[i].input);
 734                                         buffer_free(&sockets[i].output);
 735                                         break;
 736                                 }
 737                                 buffer_consume(&sockets[i].output, len);
 738                         }
 739                         if (FD_ISSET(sockets[i].fd, readset)) {
 740                                 do {
 741                                         len = read(sockets[i].fd, buf, sizeof(buf));
 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_append(&sockets[i].input, buf, len);
 756                                 process_message(&sockets[i]);
 757                         }
 758                         break;
 759                 default:
 760                         fatal("Unknown type %d", sockets[i].type);
 761                 }
 762 }
 763
 764 static void
 765 cleanup_socket(void *p)
 766 {
 767         if (socket_name[0])
 768                 unlink(socket_name);
 769         if (socket_dir[0])
 770                 rmdir(socket_dir);
 771 }
 772
 773 static void
 774 cleanup_exit(int i)
 775 {
 776         cleanup_socket(NULL);
 777         exit(i);
 778 }
 779
 780 static void
 781 cleanup_handler(int sig)
 782 {
 783         cleanup_socket(NULL);
 784         _exit(2);
 785 }
 786
 787 static void
 788 check_parent_exists(int sig)
 789 {
 790         int save_errno = errno;
 791
 792         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 793                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 794                 cleanup_handler(sig); /* safe */
 795         }
 796         signal(SIGALRM, check_parent_exists);
 797         alarm(10);
 798         errno = save_errno;
 799 }
 800
 801 static void
 802 usage(void)
 803 {
 804         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 805             __progname);
 806         fprintf(stderr, "Options:\n");
 807         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 808         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 809         fprintf(stderr, "  -k          Kill the current agent.\n");
 810         fprintf(stderr, "  -d          Debug mode.\n");
 811         exit(1);
 812 }
 813
 814 int
 815 main(int ac, char **av)
 816 {
 817         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 818         struct sockaddr_un sunaddr;
 819 #ifdef HAVE_SETRLIMIT
 820         struct rlimit rlim;
 821 #endif
 822 #ifdef HAVE_CYGWIN
 823         int prev_mask;
 824 #endif
 825         pid_t pid;
 826         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 827         extern int optind;
 828         fd_set *readsetp = NULL, *writesetp = NULL;
 829
 830         SSLeay_add_all_algorithms();
 831
 832         __progname = get_progname(av[0]);
 833         init_rng();
 834         seed_rng();
 835
 836 #ifdef __GNU_LIBRARY__
 837         while ((ch = getopt(ac, av, "+cdks")) != -1) {
 838 #else /* __GNU_LIBRARY__ */
 839         while ((ch = getopt(ac, av, "cdks")) != -1) {
 840 #endif /* __GNU_LIBRARY__ */
 841                 switch (ch) {
 842                 case 'c':
 843                         if (s_flag)
 844                                 usage();
 845                         c_flag++;
 846                         break;
 847                 case 'k':
 848                         k_flag++;
 849                         break;
 850                 case 's':
 851                         if (c_flag)
 852                                 usage();
 853                         s_flag++;
 854                         break;
 855                 case 'd':
 856                         if (d_flag)
 857                                 usage();
 858                         d_flag++;
 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         /* Create private directory for agent socket */
 901         strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 902         if (mkdtemp(socket_dir) == NULL) {
 903                 perror("mkdtemp: private socket dir");
 904                 exit(1);
 905         }
 906         snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 907             parent_pid);
 908
 909         /*
 910          * Create socket early so it will exist before command gets run from
 911          * the parent.
 912          */
 913         sock = socket(AF_UNIX, SOCK_STREAM, 0);
 914         if (sock < 0) {
 915                 perror("socket");
 916                 cleanup_exit(1);
 917         }
 918         memset(&sunaddr, 0, sizeof(sunaddr));
 919         sunaddr.sun_family = AF_UNIX;
 920         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
 921 #ifdef HAVE_CYGWIN
 922         prev_mask = umask(0177);
 923 #endif
 924         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
 925                 perror("bind");
 926 #ifdef HAVE_CYGWIN
 927                 umask(prev_mask);
 928 #endif
 929                 cleanup_exit(1);
 930         }
 931 #ifdef HAVE_CYGWIN
 932         umask(prev_mask);
 933 #endif
 934         if (listen(sock, 5) < 0) {
 935                 perror("listen");
 936                 cleanup_exit(1);
 937         }
 938
 939         /*
 940          * Fork, and have the parent execute the command, if any, or present
 941          * the socket data.  The child continues as the authentication agent.
 942          */
 943         if (d_flag) {
 944                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
 945                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 946                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 947                     SSH_AUTHSOCKET_ENV_NAME);
 948                 printf("echo Agent pid %d;\n", parent_pid);
 949                 goto skip;
 950         }
 951         pid = fork();
 952         if (pid == -1) {
 953                 perror("fork");
 954                 cleanup_exit(1);
 955         }
 956         if (pid != 0) {         /* Parent - execute the given command. */
 957                 close(sock);
 958                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
 959                 if (ac == 0) {
 960                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
 961                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
 962                             SSH_AUTHSOCKET_ENV_NAME);
 963                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
 964                             SSH_AGENTPID_ENV_NAME);
 965                         printf("echo Agent pid %d;\n", pid);
 966                         exit(0);
 967                 }
 968                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
 969                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
 970                         perror("setenv");
 971                         exit(1);
 972                 }
 973                 execvp(av[0], av);
 974                 perror(av[0]);
 975                 exit(1);
 976         }
 977         /* child */
 978         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
 979
 980         if (setsid() == -1) {
 981                 error("setsid: %s", strerror(errno));
 982                 cleanup_exit(1);
 983         }
 984
 985         (void)chdir("/");
 986         close(0);
 987         close(1);
 988         close(2);
 989
 990 #ifdef HAVE_SETRLIMIT
 991         /* deny core dumps, since memory contains unencrypted private keys */
 992         rlim.rlim_cur = rlim.rlim_max = 0;
 993         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
 994                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
 995                 cleanup_exit(1);
 996         }
 997 #endif
 998
 999 skip:
1000         fatal_add_cleanup(cleanup_socket, NULL);
1001         new_socket(AUTH_SOCKET, sock);
1002         if (ac > 0) {
1003                 signal(SIGALRM, check_parent_exists);
1004                 alarm(10);
1005         }
1006         idtab_init();
1007         if (!d_flag)
1008                 signal(SIGINT, SIG_IGN);
1009         signal(SIGPIPE, SIG_IGN);
1010         signal(SIGHUP, cleanup_handler);
1011         signal(SIGTERM, cleanup_handler);
1012         nalloc = 0;
1013
1014         while (1) {
1015                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1016                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1017                         if (errno == EINTR)
1018                                 continue;
1019                         fatal("select: %s", strerror(errno));
1020                 }
1021                 after_select(readsetp, writesetp);
1022         }
1023         /* NOTREACHED */
1024 }