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 1.94 2002/06/15 01:27:48 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         Buffer request;
  70 } SocketEntry;
  71
  72 u_int sockets_alloc = 0;
  73 SocketEntry *sockets = NULL;
  74
  75 typedef struct identity {
  76         TAILQ_ENTRY(identity) next;
  77         Key *key;
  78         char *comment;
  79         u_int death;
  80 } Identity;
  81
  82 typedef struct {
  83         int nentries;
  84         TAILQ_HEAD(idqueue, identity) idlist;
  85 } Idtab;
  86
  87 /* private key table, one per protocol version */
  88 Idtab idtable[3];
  89
  90 int max_fd = 0;
  91
  92 /* pid of shell == parent of agent */
  93 pid_t parent_pid = -1;
  94
  95 /* pathname and directory for AUTH_SOCKET */
  96 char socket_name[1024];
  97 char socket_dir[1024];
  98
  99 /* locking */
 100 int locked = 0;
 101 char *lock_passwd = NULL;
 102
 103 #ifdef HAVE___PROGNAME
 104 extern char *__progname;
 105 #else
 106 char *__progname;
 107 #endif
 108
 109 static void
 110 idtab_init(void)
 111 {
 112         int i;
 113         for (i = 0; i <=2; i++) {
 114                 TAILQ_INIT(&idtable[i].idlist);
 115                 idtable[i].nentries = 0;
 116         }
 117 }
 118
 119 /* return private key table for requested protocol version */
 120 static Idtab *
 121 idtab_lookup(int version)
 122 {
 123         if (version < 1 || version > 2)
 124                 fatal("internal error, bad protocol version %d", version);
 125         return &idtable[version];
 126 }
 127
 128 static void
 129 free_identity(Identity *id)
 130 {
 131         key_free(id->key);
 132         xfree(id->comment);
 133         xfree(id);
 134 }
 135
 136 /* return matching private key for given public key */
 137 static Identity *
 138 lookup_identity(Key *key, int version)
 139 {
 140         Identity *id;
 141
 142         Idtab *tab = idtab_lookup(version);
 143         TAILQ_FOREACH(id, &tab->idlist, next) {
 144                 if (key_equal(key, id->key))
 145                         return (id);
 146         }
 147         return (NULL);
 148 }
 149
 150 /* send list of supported public keys to 'client' */
 151 static void
 152 process_request_identities(SocketEntry *e, int version)
 153 {
 154         Idtab *tab = idtab_lookup(version);
 155         Buffer msg;
 156         Identity *id;
 157
 158         buffer_init(&msg);
 159         buffer_put_char(&msg, (version == 1) ?
 160             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 161         buffer_put_int(&msg, tab->nentries);
 162         TAILQ_FOREACH(id, &tab->idlist, next) {
 163                 if (id->key->type == KEY_RSA1) {
 164                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 165                         buffer_put_bignum(&msg, id->key->rsa->e);
 166                         buffer_put_bignum(&msg, id->key->rsa->n);
 167                 } else {
 168                         u_char *blob;
 169                         u_int blen;
 170                         key_to_blob(id->key, &blob, &blen);
 171                         buffer_put_string(&msg, blob, blen);
 172                         xfree(blob);
 173                 }
 174                 buffer_put_cstring(&msg, id->comment);
 175         }
 176         buffer_put_int(&e->output, buffer_len(&msg));
 177         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 178         buffer_free(&msg);
 179 }
 180
 181 /* ssh1 only */
 182 static void
 183 process_authentication_challenge1(SocketEntry *e)
 184 {
 185         Identity *id;
 186         Key *key;
 187         BIGNUM *challenge;
 188         int i, len;
 189         Buffer msg;
 190         MD5_CTX md;
 191         u_char buf[32], mdbuf[16], session_id[16];
 192         u_int response_type;
 193
 194         buffer_init(&msg);
 195         key = key_new(KEY_RSA1);
 196         if ((challenge = BN_new()) == NULL)
 197                 fatal("process_authentication_challenge1: BN_new failed");
 198
 199         buffer_get_int(&e->request);                            /* ignored */
 200         buffer_get_bignum(&e->request, key->rsa->e);
 201         buffer_get_bignum(&e->request, key->rsa->n);
 202         buffer_get_bignum(&e->request, challenge);
 203
 204         /* Only protocol 1.1 is supported */
 205         if (buffer_len(&e->request) == 0)
 206                 goto failure;
 207         buffer_get(&e->request, session_id, 16);
 208         response_type = buffer_get_int(&e->request);
 209         if (response_type != 1)
 210                 goto failure;
 211
 212         id = lookup_identity(key, 1);
 213         if (id != NULL) {
 214                 Key *private = id->key;
 215                 /* Decrypt the challenge using the private key. */
 216                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 217                         goto failure;
 218
 219                 /* The response is MD5 of decrypted challenge plus session id. */
 220                 len = BN_num_bytes(challenge);
 221                 if (len <= 0 || len > 32) {
 222                         log("process_authentication_challenge: bad challenge length %d", len);
 223                         goto failure;
 224                 }
 225                 memset(buf, 0, 32);
 226                 BN_bn2bin(challenge, buf + 32 - len);
 227                 MD5_Init(&md);
 228                 MD5_Update(&md, buf, 32);
 229                 MD5_Update(&md, session_id, 16);
 230                 MD5_Final(mdbuf, &md);
 231
 232                 /* Send the response. */
 233                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 234                 for (i = 0; i < 16; i++)
 235                         buffer_put_char(&msg, mdbuf[i]);
 236                 goto send;
 237         }
 238
 239 failure:
 240         /* Unknown identity or protocol error.  Send failure. */
 241         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 242 send:
 243         buffer_put_int(&e->output, buffer_len(&msg));
 244         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 245         key_free(key);
 246         BN_clear_free(challenge);
 247         buffer_free(&msg);
 248 }
 249
 250 /* ssh2 only */
 251 static void
 252 process_sign_request2(SocketEntry *e)
 253 {
 254         extern int datafellows;
 255         Key *key;
 256         u_char *blob, *data, *signature = NULL;
 257         u_int blen, dlen, slen = 0;
 258         int flags;
 259         Buffer msg;
 260         int ok = -1;
 261
 262         datafellows = 0;
 263
 264         blob = buffer_get_string(&e->request, &blen);
 265         data = buffer_get_string(&e->request, &dlen);
 266
 267         flags = buffer_get_int(&e->request);
 268         if (flags & SSH_AGENT_OLD_SIGNATURE)
 269                 datafellows = SSH_BUG_SIGBLOB;
 270
 271         key = key_from_blob(blob, blen);
 272         if (key != NULL) {
 273                 Identity *id = lookup_identity(key, 2);
 274                 if (id != NULL)
 275                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 276         }
 277         key_free(key);
 278         buffer_init(&msg);
 279         if (ok == 0) {
 280                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 281                 buffer_put_string(&msg, signature, slen);
 282         } else {
 283                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 284         }
 285         buffer_put_int(&e->output, buffer_len(&msg));
 286         buffer_append(&e->output, buffer_ptr(&msg),
 287             buffer_len(&msg));
 288         buffer_free(&msg);
 289         xfree(data);
 290         xfree(blob);
 291         if (signature != NULL)
 292                 xfree(signature);
 293 }
 294
 295 /* shared */
 296 static void
 297 process_remove_identity(SocketEntry *e, int version)
 298 {
 299         Key *key = NULL;
 300         u_char *blob;
 301         u_int blen;
 302         u_int bits;
 303         int success = 0;
 304
 305         switch (version) {
 306         case 1:
 307                 key = key_new(KEY_RSA1);
 308                 bits = buffer_get_int(&e->request);
 309                 buffer_get_bignum(&e->request, key->rsa->e);
 310                 buffer_get_bignum(&e->request, key->rsa->n);
 311
 312                 if (bits != key_size(key))
 313                         log("Warning: identity keysize mismatch: actual %d, announced %d",
 314                             key_size(key), bits);
 315                 break;
 316         case 2:
 317                 blob = buffer_get_string(&e->request, &blen);
 318                 key = key_from_blob(blob, blen);
 319                 xfree(blob);
 320                 break;
 321         }
 322         if (key != NULL) {
 323                 Identity *id = lookup_identity(key, version);
 324                 if (id != NULL) {
 325                         /*
 326                          * We have this key.  Free the old key.  Since we
 327                          * don\'t want to leave empty slots in the middle of
 328                          * the array, we actually free the key there and move
 329                          * all the entries between the empty slot and the end
 330                          * of the array.
 331                          */
 332                         Idtab *tab = idtab_lookup(version);
 333                         if (tab->nentries < 1)
 334                                 fatal("process_remove_identity: "
 335                                     "internal error: tab->nentries %d",
 336                                     tab->nentries);
 337                         TAILQ_REMOVE(&tab->idlist, id, next);
 338                         free_identity(id);
 339                         tab->nentries--;
 340                         success = 1;
 341                 }
 342                 key_free(key);
 343         }
 344         buffer_put_int(&e->output, 1);
 345         buffer_put_char(&e->output,
 346             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 347 }
 348
 349 static void
 350 process_remove_all_identities(SocketEntry *e, int version)
 351 {
 352         Idtab *tab = idtab_lookup(version);
 353         Identity *id;
 354
 355         /* Loop over all identities and clear the keys. */
 356         for (id = TAILQ_FIRST(&tab->idlist); id;
 357             id = TAILQ_FIRST(&tab->idlist)) {
 358                 TAILQ_REMOVE(&tab->idlist, id, next);
 359                 free_identity(id);
 360         }
 361
 362         /* Mark that there are no identities. */
 363         tab->nentries = 0;
 364
 365         /* Send success. */
 366         buffer_put_int(&e->output, 1);
 367         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 368         return;
 369 }
 370
 371 static void
 372 reaper(void)
 373 {
 374         Idtab *tab;
 375         Identity *id, *nxt;
 376         int version;
 377         u_int now = time(NULL);
 378
 379         for (version = 1; version < 3; version++) {
 380                 tab = idtab_lookup(version);
 381                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 382                         nxt = TAILQ_NEXT(id, next);
 383                         if (id->death != 0 && now >= id->death) {
 384                                 TAILQ_REMOVE(&tab->idlist, id, next);
 385                                 free_identity(id);
 386                                 tab->nentries--;
 387                         }
 388                 }
 389         }
 390 }
 391
 392 static void
 393 process_add_identity(SocketEntry *e, int version)
 394 {
 395         Key *k = NULL;
 396         char *type_name;
 397         char *comment;
 398         int type, success = 0, death = 0;
 399         Idtab *tab = idtab_lookup(version);
 400
 401         switch (version) {
 402         case 1:
 403                 k = key_new_private(KEY_RSA1);
 404                 buffer_get_int(&e->request);                    /* ignored */
 405                 buffer_get_bignum(&e->request, k->rsa->n);
 406                 buffer_get_bignum(&e->request, k->rsa->e);
 407                 buffer_get_bignum(&e->request, k->rsa->d);
 408                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 409
 410                 /* SSH and SSL have p and q swapped */
 411                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 412                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 413
 414                 /* Generate additional parameters */
 415                 rsa_generate_additional_parameters(k->rsa);
 416                 break;
 417         case 2:
 418                 type_name = buffer_get_string(&e->request, NULL);
 419                 type = key_type_from_name(type_name);
 420                 xfree(type_name);
 421                 switch (type) {
 422                 case KEY_DSA:
 423                         k = key_new_private(type);
 424                         buffer_get_bignum2(&e->request, k->dsa->p);
 425                         buffer_get_bignum2(&e->request, k->dsa->q);
 426                         buffer_get_bignum2(&e->request, k->dsa->g);
 427                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 428                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 429                         break;
 430                 case KEY_RSA:
 431                         k = key_new_private(type);
 432                         buffer_get_bignum2(&e->request, k->rsa->n);
 433                         buffer_get_bignum2(&e->request, k->rsa->e);
 434                         buffer_get_bignum2(&e->request, k->rsa->d);
 435                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 436                         buffer_get_bignum2(&e->request, k->rsa->p);
 437                         buffer_get_bignum2(&e->request, k->rsa->q);
 438
 439                         /* Generate additional parameters */
 440                         rsa_generate_additional_parameters(k->rsa);
 441                         break;
 442                 default:
 443                         buffer_clear(&e->request);
 444                         goto send;
 445                 }
 446                 break;
 447         }
 448         comment = buffer_get_string(&e->request, NULL);
 449         if (k == NULL) {
 450                 xfree(comment);
 451                 goto send;
 452         }
 453         success = 1;
 454         while (buffer_len(&e->request)) {
 455                 switch (buffer_get_char(&e->request)) {
 456                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 457                         death = time(NULL) + buffer_get_int(&e->request);
 458                         break;
 459                 default:
 460                         break;
 461                 }
 462         }
 463         if (lookup_identity(k, version) == NULL) {
 464                 Identity *id = xmalloc(sizeof(Identity));
 465                 id->key = k;
 466                 id->comment = comment;
 467                 id->death = death;
 468                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 469                 /* Increment the number of identities. */
 470                 tab->nentries++;
 471         } else {
 472                 key_free(k);
 473                 xfree(comment);
 474         }
 475 send:
 476         buffer_put_int(&e->output, 1);
 477         buffer_put_char(&e->output,
 478             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 479 }
 480
 481 /* XXX todo: encrypt sensitive data with passphrase */
 482 static void
 483 process_lock_agent(SocketEntry *e, int lock)
 484 {
 485         char *passwd;
 486         int success = 0;
 487
 488         passwd = buffer_get_string(&e->request, NULL);
 489         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 490                 locked = 0;
 491                 memset(lock_passwd, 0, strlen(lock_passwd));
 492                 xfree(lock_passwd);
 493                 lock_passwd = NULL;
 494                 success = 1;
 495         } else if (!locked && lock) {
 496                 locked = 1;
 497                 lock_passwd = xstrdup(passwd);
 498                 success = 1;
 499         }
 500         memset(passwd, 0, strlen(passwd));
 501         xfree(passwd);
 502
 503         buffer_put_int(&e->output, 1);
 504         buffer_put_char(&e->output,
 505             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 506         return;
 507 }
 508
 509 static void
 510 no_identities(SocketEntry *e, u_int type)
 511 {
 512         Buffer msg;
 513
 514         buffer_init(&msg);
 515         buffer_put_char(&msg,
 516             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 517             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 518         buffer_put_int(&msg, 0);
 519         buffer_put_int(&e->output, buffer_len(&msg));
 520         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 521         buffer_free(&msg);
 522 }
 523
 524 #ifdef SMARTCARD
 525 static void
 526 process_add_smartcard_key (SocketEntry *e)
 527 {
 528         Identity *id;
 529         Idtab *tab;
 530         Key **keys, *k;
 531         char *sc_reader_id = NULL, *pin;
 532         int i, version, success = 0;
 533
 534         sc_reader_id = buffer_get_string(&e->request, NULL);
 535         pin = buffer_get_string(&e->request, NULL);
 536         keys = sc_get_keys(sc_reader_id, pin);
 537         xfree(sc_reader_id);
 538         xfree(pin);
 539
 540         if (keys == NULL || keys[0] == NULL) {
 541                 error("sc_get_keys failed");
 542                 goto send;
 543         }
 544         for (i = 0; keys[i] != NULL; i++) {
 545                 k = keys[i];
 546                 version = k->type == KEY_RSA1 ? 1 : 2;
 547                 tab = idtab_lookup(version);
 548                 if (lookup_identity(k, version) == NULL) {
 549                         id = xmalloc(sizeof(Identity));
 550                         id->key = k;
 551                         id->comment = xstrdup("smartcard key");
 552                         id->death = 0;
 553                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 554                         tab->nentries++;
 555                         success = 1;
 556                 } else {
 557                         key_free(k);
 558                 }
 559                 keys[i] = NULL;
 560         }
 561         xfree(keys);
 562 send:
 563         buffer_put_int(&e->output, 1);
 564         buffer_put_char(&e->output,
 565             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 566 }
 567
 568 static void
 569 process_remove_smartcard_key(SocketEntry *e)
 570 {
 571         Identity *id;
 572         Idtab *tab;
 573         Key **keys, *k = NULL;
 574         char *sc_reader_id = NULL, *pin;
 575         int i, version, success = 0;
 576
 577         sc_reader_id = buffer_get_string(&e->request, NULL);
 578         pin = buffer_get_string(&e->request, NULL);
 579         keys = sc_get_keys(sc_reader_id, pin);
 580         xfree(sc_reader_id);
 581         xfree(pin);
 582
 583         if (keys == NULL || keys[0] == NULL) {
 584                 error("sc_get_keys failed");
 585                 goto send;
 586         }
 587         for (i = 0; keys[i] != NULL; i++) {
 588                 k = keys[i];
 589                 version = k->type == KEY_RSA1 ? 1 : 2;
 590                 if ((id = lookup_identity(k, version)) != NULL) {
 591                         tab = idtab_lookup(version);
 592                         TAILQ_REMOVE(&tab->idlist, id, next);
 593                         tab->nentries--;
 594                         free_identity(id);
 595                         success = 1;
 596                 }
 597                 key_free(k);
 598                 keys[i] = NULL;
 599         }
 600         xfree(keys);
 601 send:
 602         buffer_put_int(&e->output, 1);
 603         buffer_put_char(&e->output,
 604             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 605 }
 606 #endif /* SMARTCARD */
 607
 608 /* dispatch incoming messages */
 609
 610 static void
 611 process_message(SocketEntry *e)
 612 {
 613         u_int msg_len;
 614         u_int type;
 615         u_char *cp;
 616
 617         /* kill dead keys */
 618         reaper();
 619
 620         if (buffer_len(&e->input) < 5)
 621                 return;         /* Incomplete message. */
 622         cp = buffer_ptr(&e->input);
 623         msg_len = GET_32BIT(cp);
 624         if (msg_len > 256 * 1024) {
 625                 shutdown(e->fd, SHUT_RDWR);
 626                 close(e->fd);
 627                 e->type = AUTH_UNUSED;
 628                 buffer_free(&e->input);
 629                 buffer_free(&e->output);
 630                 buffer_free(&e->request);
 631                 return;
 632         }
 633         if (buffer_len(&e->input) < msg_len + 4)
 634                 return;
 635
 636         /* move the current input to e->request */
 637         buffer_consume(&e->input, 4);
 638         buffer_clear(&e->request);
 639         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 640         buffer_consume(&e->input, msg_len);
 641         type = buffer_get_char(&e->request);
 642
 643         /* check wheter agent is locked */
 644         if (locked && type != SSH_AGENTC_UNLOCK) {
 645                 buffer_clear(&e->request);
 646                 switch (type) {
 647                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 648                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 649                         /* send empty lists */
 650                         no_identities(e, type);
 651                         break;
 652                 default:
 653                         /* send a fail message for all other request types */
 654                         buffer_put_int(&e->output, 1);
 655                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 656                 }
 657                 return;
 658         }
 659
 660         debug("type %d", type);
 661         switch (type) {
 662         case SSH_AGENTC_LOCK:
 663         case SSH_AGENTC_UNLOCK:
 664                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 665                 break;
 666         /* ssh1 */
 667         case SSH_AGENTC_RSA_CHALLENGE:
 668                 process_authentication_challenge1(e);
 669                 break;
 670         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 671                 process_request_identities(e, 1);
 672                 break;
 673         case SSH_AGENTC_ADD_RSA_IDENTITY:
 674         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 675                 process_add_identity(e, 1);
 676                 break;
 677         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 678                 process_remove_identity(e, 1);
 679                 break;
 680         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 681                 process_remove_all_identities(e, 1);
 682                 break;
 683         /* ssh2 */
 684         case SSH2_AGENTC_SIGN_REQUEST:
 685                 process_sign_request2(e);
 686                 break;
 687         case SSH2_AGENTC_REQUEST_IDENTITIES:
 688                 process_request_identities(e, 2);
 689                 break;
 690         case SSH2_AGENTC_ADD_IDENTITY:
 691         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 692                 process_add_identity(e, 2);
 693                 break;
 694         case SSH2_AGENTC_REMOVE_IDENTITY:
 695                 process_remove_identity(e, 2);
 696                 break;
 697         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 698                 process_remove_all_identities(e, 2);
 699                 break;
 700 #ifdef SMARTCARD
 701         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 702                 process_add_smartcard_key(e);
 703                 break;
 704         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 705                 process_remove_smartcard_key(e);
 706                 break;
 707 #endif /* SMARTCARD */
 708         default:
 709                 /* Unknown message.  Respond with failure. */
 710                 error("Unknown message %d", type);
 711                 buffer_clear(&e->request);
 712                 buffer_put_int(&e->output, 1);
 713                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 714                 break;
 715         }
 716 }
 717
 718 static void
 719 new_socket(sock_type type, int fd)
 720 {
 721         u_int i, old_alloc;
 722         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 723                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 724
 725         if (fd > max_fd)
 726                 max_fd = fd;
 727
 728         for (i = 0; i < sockets_alloc; i++)
 729                 if (sockets[i].type == AUTH_UNUSED) {
 730                         sockets[i].fd = fd;
 731                         sockets[i].type = type;
 732                         buffer_init(&sockets[i].input);
 733                         buffer_init(&sockets[i].output);
 734                         buffer_init(&sockets[i].request);
 735                         return;
 736                 }
 737         old_alloc = sockets_alloc;
 738         sockets_alloc += 10;
 739         if (sockets)
 740                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 741         else
 742                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 743         for (i = old_alloc; i < sockets_alloc; i++)
 744                 sockets[i].type = AUTH_UNUSED;
 745         sockets[old_alloc].type = type;
 746         sockets[old_alloc].fd = fd;
 747         buffer_init(&sockets[old_alloc].input);
 748         buffer_init(&sockets[old_alloc].output);
 749         buffer_init(&sockets[old_alloc].request);
 750 }
 751
 752 static int
 753 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 754 {
 755         u_int i, sz;
 756         int n = 0;
 757
 758         for (i = 0; i < sockets_alloc; i++) {
 759                 switch (sockets[i].type) {
 760                 case AUTH_SOCKET:
 761                 case AUTH_CONNECTION:
 762                         n = MAX(n, sockets[i].fd);
 763                         break;
 764                 case AUTH_UNUSED:
 765                         break;
 766                 default:
 767                         fatal("Unknown socket type %d", sockets[i].type);
 768                         break;
 769                 }
 770         }
 771
 772         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 773         if (*fdrp == NULL || sz > *nallocp) {
 774                 if (*fdrp)
 775                         xfree(*fdrp);
 776                 if (*fdwp)
 777                         xfree(*fdwp);
 778                 *fdrp = xmalloc(sz);
 779                 *fdwp = xmalloc(sz);
 780                 *nallocp = sz;
 781         }
 782         if (n < *fdl)
 783                 debug("XXX shrink: %d < %d", n, *fdl);
 784         *fdl = n;
 785         memset(*fdrp, 0, sz);
 786         memset(*fdwp, 0, sz);
 787
 788         for (i = 0; i < sockets_alloc; i++) {
 789                 switch (sockets[i].type) {
 790                 case AUTH_SOCKET:
 791                 case AUTH_CONNECTION:
 792                         FD_SET(sockets[i].fd, *fdrp);
 793                         if (buffer_len(&sockets[i].output) > 0)
 794                                 FD_SET(sockets[i].fd, *fdwp);
 795                         break;
 796                 default:
 797                         break;
 798                 }
 799         }
 800         return (1);
 801 }
 802
 803 static void
 804 after_select(fd_set *readset, fd_set *writeset)
 805 {
 806         u_int i;
 807         int len, sock;
 808         socklen_t slen;
 809         char buf[1024];
 810         struct sockaddr_un sunaddr;
 811
 812         for (i = 0; i < sockets_alloc; i++)
 813                 switch (sockets[i].type) {
 814                 case AUTH_UNUSED:
 815                         break;
 816                 case AUTH_SOCKET:
 817                         if (FD_ISSET(sockets[i].fd, readset)) {
 818                                 slen = sizeof(sunaddr);
 819                                 sock = accept(sockets[i].fd,
 820                                     (struct sockaddr *) &sunaddr, &slen);
 821                                 if (sock < 0) {
 822                                         error("accept from AUTH_SOCKET: %s",
 823                                             strerror(errno));
 824                                         break;
 825                                 }
 826                                 new_socket(AUTH_CONNECTION, sock);
 827                         }
 828                         break;
 829                 case AUTH_CONNECTION:
 830                         if (buffer_len(&sockets[i].output) > 0 &&
 831                             FD_ISSET(sockets[i].fd, writeset)) {
 832                                 do {
 833                                         len = write(sockets[i].fd,
 834                                             buffer_ptr(&sockets[i].output),
 835                                             buffer_len(&sockets[i].output));
 836                                         if (len == -1 && (errno == EAGAIN ||
 837                                             errno == EINTR))
 838                                                 continue;
 839                                         break;
 840                                 } while (1);
 841                                 if (len <= 0) {
 842                                         shutdown(sockets[i].fd, SHUT_RDWR);
 843                                         close(sockets[i].fd);
 844                                         sockets[i].type = AUTH_UNUSED;
 845                                         buffer_free(&sockets[i].input);
 846                                         buffer_free(&sockets[i].output);
 847                                         buffer_free(&sockets[i].request);
 848                                         break;
 849                                 }
 850                                 buffer_consume(&sockets[i].output, len);
 851                         }
 852                         if (FD_ISSET(sockets[i].fd, readset)) {
 853                                 do {
 854                                         len = read(sockets[i].fd, buf, sizeof(buf));
 855                                         if (len == -1 && (errno == EAGAIN ||
 856                                             errno == EINTR))
 857                                                 continue;
 858                                         break;
 859                                 } while (1);
 860                                 if (len <= 0) {
 861                                         shutdown(sockets[i].fd, SHUT_RDWR);
 862                                         close(sockets[i].fd);
 863                                         sockets[i].type = AUTH_UNUSED;
 864                                         buffer_free(&sockets[i].input);
 865                                         buffer_free(&sockets[i].output);
 866                                         buffer_free(&sockets[i].request);
 867                                         break;
 868                                 }
 869                                 buffer_append(&sockets[i].input, buf, len);
 870                                 process_message(&sockets[i]);
 871                         }
 872                         break;
 873                 default:
 874                         fatal("Unknown type %d", sockets[i].type);
 875                 }
 876 }
 877
 878 static void
 879 cleanup_socket(void *p)
 880 {
 881         if (socket_name[0])
 882                 unlink(socket_name);
 883         if (socket_dir[0])
 884                 rmdir(socket_dir);
 885 }
 886
 887 static void
 888 cleanup_exit(int i)
 889 {
 890         cleanup_socket(NULL);
 891         exit(i);
 892 }
 893
 894 static void
 895 cleanup_handler(int sig)
 896 {
 897         cleanup_socket(NULL);
 898         _exit(2);
 899 }
 900
 901 static void
 902 check_parent_exists(int sig)
 903 {
 904         int save_errno = errno;
 905
 906         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 907                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 908                 cleanup_handler(sig); /* safe */
 909         }
 910         signal(SIGALRM, check_parent_exists);
 911         alarm(10);
 912         errno = save_errno;
 913 }
 914
 915 static void
 916 usage(void)
 917 {
 918         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 919             __progname);
 920         fprintf(stderr, "Options:\n");
 921         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 922         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 923         fprintf(stderr, "  -k          Kill the current agent.\n");
 924         fprintf(stderr, "  -d          Debug mode.\n");
 925         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 926         exit(1);
 927 }
 928
 929 int
 930 main(int ac, char **av)
 931 {
 932         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 933         struct sockaddr_un sunaddr;
 934 #ifdef HAVE_SETRLIMIT
 935         struct rlimit rlim;
 936 #endif
 937 #ifdef HAVE_CYGWIN
 938         int prev_mask;
 939 #endif
 940         pid_t pid;
 941         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 942         char *agentsocket = NULL;
 943         extern int optind;
 944         fd_set *readsetp = NULL, *writesetp = NULL;
 945
 946         SSLeay_add_all_algorithms();
 947
 948         __progname = get_progname(av[0]);
 949         init_rng();
 950         seed_rng();
 951
 952 #ifdef __GNU_LIBRARY__
 953         while ((ch = getopt(ac, av, "+cdksa:")) != -1) {
 954 #else /* __GNU_LIBRARY__ */
 955         while ((ch = getopt(ac, av, "cdksa:")) != -1) {
 956 #endif /* __GNU_LIBRARY__ */
 957                 switch (ch) {
 958                 case 'c':
 959                         if (s_flag)
 960                                 usage();
 961                         c_flag++;
 962                         break;
 963                 case 'k':
 964                         k_flag++;
 965                         break;
 966                 case 's':
 967                         if (c_flag)
 968                                 usage();
 969                         s_flag++;
 970                         break;
 971                 case 'd':
 972                         if (d_flag)
 973                                 usage();
 974                         d_flag++;
 975                         break;
 976                 case 'a':
 977                         agentsocket = optarg;
 978                         break;
 979                 default:
 980                         usage();
 981                 }
 982         }
 983         ac -= optind;
 984         av += optind;
 985
 986         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
 987                 usage();
 988
 989         if (ac == 0 && !c_flag && !s_flag) {
 990                 shell = getenv("SHELL");
 991                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 992                         c_flag = 1;
 993         }
 994         if (k_flag) {
 995                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 996                 if (pidstr == NULL) {
 997                         fprintf(stderr, "%s not set, cannot kill agent\n",
 998                             SSH_AGENTPID_ENV_NAME);
 999                         exit(1);
1000                 }
1001                 pid = atoi(pidstr);
1002                 if (pid < 1) {
1003                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
1004                             SSH_AGENTPID_ENV_NAME, pidstr);
1005                         exit(1);
1006                 }
1007                 if (kill(pid, SIGTERM) == -1) {
1008                         perror("kill");
1009                         exit(1);
1010                 }
1011                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1012                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1013                 printf(format, SSH_AGENTPID_ENV_NAME);
1014                 printf("echo Agent pid %ld killed;\n", (long)pid);
1015                 exit(0);
1016         }
1017         parent_pid = getpid();
1018
1019         if (agentsocket == NULL) {
1020                 /* Create private directory for agent socket */
1021                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
1022                 if (mkdtemp(socket_dir) == NULL) {
1023                         perror("mkdtemp: private socket dir");
1024                         exit(1);
1025                 }
1026                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1027                     (long)parent_pid);
1028         } else {
1029                 /* Try to use specified agent socket */
1030                 socket_dir[0] = '\0';
1031                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1032         }
1033
1034         /*
1035          * Create socket early so it will exist before command gets run from
1036          * the parent.
1037          */
1038         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1039         if (sock < 0) {
1040                 perror("socket");
1041                 cleanup_exit(1);
1042         }
1043         memset(&sunaddr, 0, sizeof(sunaddr));
1044         sunaddr.sun_family = AF_UNIX;
1045         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1046 #ifdef HAVE_CYGWIN
1047         prev_mask = umask(0177);
1048 #endif
1049         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1050                 perror("bind");
1051 #ifdef HAVE_CYGWIN
1052                 umask(prev_mask);
1053 #endif
1054                 cleanup_exit(1);
1055         }
1056 #ifdef HAVE_CYGWIN
1057         umask(prev_mask);
1058 #endif
1059         if (listen(sock, 5) < 0) {
1060                 perror("listen");
1061                 cleanup_exit(1);
1062         }
1063
1064         /*
1065          * Fork, and have the parent execute the command, if any, or present
1066          * the socket data.  The child continues as the authentication agent.
1067          */
1068         if (d_flag) {
1069                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1070                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1071                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1072                     SSH_AUTHSOCKET_ENV_NAME);
1073                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1074                 goto skip;
1075         }
1076         pid = fork();
1077         if (pid == -1) {
1078                 perror("fork");
1079                 cleanup_exit(1);
1080         }
1081         if (pid != 0) {         /* Parent - execute the given command. */
1082                 close(sock);
1083                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1084                 if (ac == 0) {
1085                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1086                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1087                             SSH_AUTHSOCKET_ENV_NAME);
1088                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1089                             SSH_AGENTPID_ENV_NAME);
1090                         printf("echo Agent pid %ld;\n", (long)pid);
1091                         exit(0);
1092                 }
1093                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1094                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1095                         perror("setenv");
1096                         exit(1);
1097                 }
1098                 execvp(av[0], av);
1099                 perror(av[0]);
1100                 exit(1);
1101         }
1102         /* child */
1103         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1104
1105         if (setsid() == -1) {
1106                 error("setsid: %s", strerror(errno));
1107                 cleanup_exit(1);
1108         }
1109
1110         (void)chdir("/");
1111         close(0);
1112         close(1);
1113         close(2);
1114
1115 #ifdef HAVE_SETRLIMIT
1116         /* deny core dumps, since memory contains unencrypted private keys */
1117         rlim.rlim_cur = rlim.rlim_max = 0;
1118         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1119                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1120                 cleanup_exit(1);
1121         }
1122 #endif
1123
1124 skip:
1125         fatal_add_cleanup(cleanup_socket, NULL);
1126         new_socket(AUTH_SOCKET, sock);
1127         if (ac > 0) {
1128                 signal(SIGALRM, check_parent_exists);
1129                 alarm(10);
1130         }
1131         idtab_init();
1132         if (!d_flag)
1133                 signal(SIGINT, SIG_IGN);
1134         signal(SIGPIPE, SIG_IGN);
1135         signal(SIGHUP, cleanup_handler);
1136         signal(SIGTERM, cleanup_handler);
1137         nalloc = 0;
1138
1139         while (1) {
1140                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1141                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1142                         if (errno == EINTR)
1143                                 continue;
1144                         fatal("select: %s", strerror(errno));
1145                 }
1146                 after_select(readsetp, writesetp);
1147         }
1148         /* NOTREACHED */
1149 }