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 1.88 2002/06/05 19:57:12 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 } Identity;
  80
  81 typedef struct {
  82         int nentries;
  83         TAILQ_HEAD(idqueue, identity) idlist;
  84 } Idtab;
  85
  86 /* private key table, one per protocol version */
  87 Idtab idtable[3];
  88
  89 int max_fd = 0;
  90
  91 /* pid of shell == parent of agent */
  92 pid_t parent_pid = -1;
  93
  94 /* pathname and directory for AUTH_SOCKET */
  95 char socket_name[1024];
  96 char socket_dir[1024];
  97
  98 /* locking */
  99 int locked = 0;
 100 char *lock_passwd = NULL;
 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->request);                            /* ignored */
 199         buffer_get_bignum(&e->request, key->rsa->e);
 200         buffer_get_bignum(&e->request, key->rsa->n);
 201         buffer_get_bignum(&e->request, challenge);
 202
 203         /* Only protocol 1.1 is supported */
 204         if (buffer_len(&e->request) == 0)
 205                 goto failure;
 206         buffer_get(&e->request, session_id, 16);
 207         response_type = buffer_get_int(&e->request);
 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->request, &blen);
 264         data = buffer_get_string(&e->request, &dlen);
 265
 266         flags = buffer_get_int(&e->request);
 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->request);
 308                 buffer_get_bignum(&e->request, key->rsa->e);
 309                 buffer_get_bignum(&e->request, 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->request, &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->request);                    /* ignored */
 383                 buffer_get_bignum(&e->request, k->rsa->n);
 384                 buffer_get_bignum(&e->request, k->rsa->e);
 385                 buffer_get_bignum(&e->request, k->rsa->d);
 386                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 387
 388                 /* SSH and SSL have p and q swapped */
 389                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 390                 buffer_get_bignum(&e->request, 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->request, 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->request, k->dsa->p);
 403                         buffer_get_bignum2(&e->request, k->dsa->q);
 404                         buffer_get_bignum2(&e->request, k->dsa->g);
 405                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 406                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 407                         break;
 408                 case KEY_RSA:
 409                         k = key_new_private(type);
 410                         buffer_get_bignum2(&e->request, k->rsa->n);
 411                         buffer_get_bignum2(&e->request, k->rsa->e);
 412                         buffer_get_bignum2(&e->request, k->rsa->d);
 413                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 414                         buffer_get_bignum2(&e->request, k->rsa->p);
 415                         buffer_get_bignum2(&e->request, k->rsa->q);
 416
 417                         /* Generate additional parameters */
 418                         rsa_generate_additional_parameters(k->rsa);
 419                         break;
 420                 default:
 421                         buffer_clear(&e->request);
 422                         goto send;
 423                 }
 424                 break;
 425         }
 426         comment = buffer_get_string(&e->request, 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 /* XXX todo: encrypt sensitive data with passphrase */
 450 static void
 451 process_lock_agent(SocketEntry *e, int lock)
 452 {
 453         char *passwd;
 454         int success = 0;
 455
 456         passwd = buffer_get_string(&e->request, NULL);
 457         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 458                 locked = 0;
 459                 memset(lock_passwd, 0, strlen(lock_passwd));
 460                 xfree(lock_passwd);
 461                 lock_passwd = NULL;
 462                 success = 1;
 463         } else if (!locked && lock) {
 464                 locked = 1;
 465                 lock_passwd = xstrdup(passwd);
 466                 success = 1;
 467         }
 468         memset(passwd, 0, strlen(passwd));
 469         xfree(passwd);
 470
 471         buffer_put_int(&e->output, 1);
 472         buffer_put_char(&e->output,
 473             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 474         return;
 475 }
 476
 477 static void
 478 no_identities(SocketEntry *e, u_int type)
 479 {
 480         Buffer msg;
 481
 482         buffer_init(&msg);
 483         buffer_put_char(&msg,
 484             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 485             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 486         buffer_put_int(&msg, 0);
 487         buffer_put_int(&e->output, buffer_len(&msg));
 488         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 489         buffer_free(&msg);
 490 }
 491
 492 #ifdef SMARTCARD
 493 static void
 494 process_add_smartcard_key (SocketEntry *e)
 495 {
 496         Identity *id;
 497         Idtab *tab;
 498         Key **keys, *k;
 499         char *sc_reader_id = NULL, *pin;
 500         int i, version, success = 0;
 501
 502         sc_reader_id = buffer_get_string(&e->request, NULL);
 503         pin = buffer_get_string(&e->request, 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                 tab = idtab_lookup(version);
 516                 if (lookup_identity(k, version) == NULL) {
 517                         id = xmalloc(sizeof(Identity));
 518                         id->key = k;
 519                         id->comment = xstrdup("smartcard key");
 520                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 521                         tab->nentries++;
 522                         success = 1;
 523                 } else {
 524                         key_free(k);
 525                 }
 526                 keys[i] = NULL;
 527         }
 528         xfree(keys);
 529 send:
 530         buffer_put_int(&e->output, 1);
 531         buffer_put_char(&e->output,
 532             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 533 }
 534
 535 static void
 536 process_remove_smartcard_key(SocketEntry *e)
 537 {
 538         Identity *id;
 539         Idtab *tab;
 540         Key **keys, *k = NULL;
 541         char *sc_reader_id = NULL, *pin;
 542         int i, version, success = 0;
 543
 544         sc_reader_id = buffer_get_string(&e->request, NULL);
 545         pin = buffer_get_string(&e->request, NULL);
 546         keys = sc_get_keys(sc_reader_id, pin);
 547         xfree(sc_reader_id);
 548         xfree(pin);
 549
 550         if (keys == NULL || keys[0] == NULL) {
 551                 error("sc_get_keys failed");
 552                 goto send;
 553         }
 554         for (i = 0; keys[i] != NULL; i++) {
 555                 k = keys[i];
 556                 version = k->type == KEY_RSA1 ? 1 : 2;
 557                 if ((id = lookup_identity(k, version)) != NULL) {
 558                         tab = idtab_lookup(version);
 559                         TAILQ_REMOVE(&tab->idlist, id, next);
 560                         tab->nentries--;
 561                         free_identity(id);
 562                         success = 1;
 563                 }
 564                 key_free(k);
 565                 keys[i] = NULL;
 566         }
 567         xfree(keys);
 568 send:
 569         buffer_put_int(&e->output, 1);
 570         buffer_put_char(&e->output,
 571             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 572 }
 573 #endif /* SMARTCARD */
 574
 575 /* dispatch incoming messages */
 576
 577 static void
 578 process_message(SocketEntry *e)
 579 {
 580         u_int msg_len;
 581         u_int type;
 582         u_char *cp;
 583         if (buffer_len(&e->input) < 5)
 584                 return;         /* Incomplete message. */
 585         cp = buffer_ptr(&e->input);
 586         msg_len = GET_32BIT(cp);
 587         if (msg_len > 256 * 1024) {
 588                 shutdown(e->fd, SHUT_RDWR);
 589                 close(e->fd);
 590                 e->type = AUTH_UNUSED;
 591                 buffer_free(&e->input);
 592                 buffer_free(&e->output);
 593                 buffer_free(&e->request);
 594                 return;
 595         }
 596         if (buffer_len(&e->input) < msg_len + 4)
 597                 return;
 598
 599         /* move the current input to e->request */
 600         buffer_consume(&e->input, 4);
 601         buffer_clear(&e->request);
 602         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 603         buffer_consume(&e->input, msg_len);
 604         type = buffer_get_char(&e->request);
 605
 606         /* check wheter agent is locked */
 607         if (locked && type != SSH_AGENTC_UNLOCK) {
 608                 buffer_clear(&e->request);
 609                 switch (type) {
 610                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 611                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 612                         /* send empty lists */
 613                         no_identities(e, type);
 614                         break;
 615                 default:
 616                         /* send a fail message for all other request types */
 617                         buffer_put_int(&e->output, 1);
 618                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 619                 }
 620                 return;
 621         }
 622
 623         debug("type %d", type);
 624         switch (type) {
 625         case SSH_AGENTC_LOCK:
 626         case SSH_AGENTC_UNLOCK:
 627                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 628                 break;
 629         /* ssh1 */
 630         case SSH_AGENTC_RSA_CHALLENGE:
 631                 process_authentication_challenge1(e);
 632                 break;
 633         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 634                 process_request_identities(e, 1);
 635                 break;
 636         case SSH_AGENTC_ADD_RSA_IDENTITY:
 637                 process_add_identity(e, 1);
 638                 break;
 639         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 640                 process_remove_identity(e, 1);
 641                 break;
 642         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 643                 process_remove_all_identities(e, 1);
 644                 break;
 645         /* ssh2 */
 646         case SSH2_AGENTC_SIGN_REQUEST:
 647                 process_sign_request2(e);
 648                 break;
 649         case SSH2_AGENTC_REQUEST_IDENTITIES:
 650                 process_request_identities(e, 2);
 651                 break;
 652         case SSH2_AGENTC_ADD_IDENTITY:
 653                 process_add_identity(e, 2);
 654                 break;
 655         case SSH2_AGENTC_REMOVE_IDENTITY:
 656                 process_remove_identity(e, 2);
 657                 break;
 658         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 659                 process_remove_all_identities(e, 2);
 660                 break;
 661 #ifdef SMARTCARD
 662         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 663                 process_add_smartcard_key(e);
 664                 break;
 665         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 666                 process_remove_smartcard_key(e);
 667                 break;
 668 #endif /* SMARTCARD */
 669         default:
 670                 /* Unknown message.  Respond with failure. */
 671                 error("Unknown message %d", type);
 672                 buffer_clear(&e->request);
 673                 buffer_put_int(&e->output, 1);
 674                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 675                 break;
 676         }
 677 }
 678
 679 static void
 680 new_socket(sock_type type, int fd)
 681 {
 682         u_int i, old_alloc;
 683         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 684                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 685
 686         if (fd > max_fd)
 687                 max_fd = fd;
 688
 689         for (i = 0; i < sockets_alloc; i++)
 690                 if (sockets[i].type == AUTH_UNUSED) {
 691                         sockets[i].fd = fd;
 692                         sockets[i].type = type;
 693                         buffer_init(&sockets[i].input);
 694                         buffer_init(&sockets[i].output);
 695                         buffer_init(&sockets[i].request);
 696                         return;
 697                 }
 698         old_alloc = sockets_alloc;
 699         sockets_alloc += 10;
 700         if (sockets)
 701                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 702         else
 703                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 704         for (i = old_alloc; i < sockets_alloc; i++)
 705                 sockets[i].type = AUTH_UNUSED;
 706         sockets[old_alloc].type = type;
 707         sockets[old_alloc].fd = fd;
 708         buffer_init(&sockets[old_alloc].input);
 709         buffer_init(&sockets[old_alloc].output);
 710         buffer_init(&sockets[old_alloc].request);
 711 }
 712
 713 static int
 714 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 715 {
 716         u_int i, sz;
 717         int n = 0;
 718
 719         for (i = 0; i < sockets_alloc; i++) {
 720                 switch (sockets[i].type) {
 721                 case AUTH_SOCKET:
 722                 case AUTH_CONNECTION:
 723                         n = MAX(n, sockets[i].fd);
 724                         break;
 725                 case AUTH_UNUSED:
 726                         break;
 727                 default:
 728                         fatal("Unknown socket type %d", sockets[i].type);
 729                         break;
 730                 }
 731         }
 732
 733         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 734         if (*fdrp == NULL || sz > *nallocp) {
 735                 if (*fdrp)
 736                         xfree(*fdrp);
 737                 if (*fdwp)
 738                         xfree(*fdwp);
 739                 *fdrp = xmalloc(sz);
 740                 *fdwp = xmalloc(sz);
 741                 *nallocp = sz;
 742         }
 743         if (n < *fdl)
 744                 debug("XXX shrink: %d < %d", n, *fdl);
 745         *fdl = n;
 746         memset(*fdrp, 0, sz);
 747         memset(*fdwp, 0, sz);
 748
 749         for (i = 0; i < sockets_alloc; i++) {
 750                 switch (sockets[i].type) {
 751                 case AUTH_SOCKET:
 752                 case AUTH_CONNECTION:
 753                         FD_SET(sockets[i].fd, *fdrp);
 754                         if (buffer_len(&sockets[i].output) > 0)
 755                                 FD_SET(sockets[i].fd, *fdwp);
 756                         break;
 757                 default:
 758                         break;
 759                 }
 760         }
 761         return (1);
 762 }
 763
 764 static void
 765 after_select(fd_set *readset, fd_set *writeset)
 766 {
 767         u_int i;
 768         int len, sock;
 769         socklen_t slen;
 770         char buf[1024];
 771         struct sockaddr_un sunaddr;
 772
 773         for (i = 0; i < sockets_alloc; i++)
 774                 switch (sockets[i].type) {
 775                 case AUTH_UNUSED:
 776                         break;
 777                 case AUTH_SOCKET:
 778                         if (FD_ISSET(sockets[i].fd, readset)) {
 779                                 slen = sizeof(sunaddr);
 780                                 sock = accept(sockets[i].fd,
 781                                     (struct sockaddr *) &sunaddr, &slen);
 782                                 if (sock < 0) {
 783                                         error("accept from AUTH_SOCKET: %s",
 784                                             strerror(errno));
 785                                         break;
 786                                 }
 787                                 new_socket(AUTH_CONNECTION, sock);
 788                         }
 789                         break;
 790                 case AUTH_CONNECTION:
 791                         if (buffer_len(&sockets[i].output) > 0 &&
 792                             FD_ISSET(sockets[i].fd, writeset)) {
 793                                 do {
 794                                         len = write(sockets[i].fd,
 795                                             buffer_ptr(&sockets[i].output),
 796                                             buffer_len(&sockets[i].output));
 797                                         if (len == -1 && (errno == EAGAIN ||
 798                                             errno == EINTR))
 799                                                 continue;
 800                                         break;
 801                                 } while (1);
 802                                 if (len <= 0) {
 803                                         shutdown(sockets[i].fd, SHUT_RDWR);
 804                                         close(sockets[i].fd);
 805                                         sockets[i].type = AUTH_UNUSED;
 806                                         buffer_free(&sockets[i].input);
 807                                         buffer_free(&sockets[i].output);
 808                                         buffer_free(&sockets[i].request);
 809                                         break;
 810                                 }
 811                                 buffer_consume(&sockets[i].output, len);
 812                         }
 813                         if (FD_ISSET(sockets[i].fd, readset)) {
 814                                 do {
 815                                         len = read(sockets[i].fd, buf, sizeof(buf));
 816                                         if (len == -1 && (errno == EAGAIN ||
 817                                             errno == EINTR))
 818                                                 continue;
 819                                         break;
 820                                 } while (1);
 821                                 if (len <= 0) {
 822                                         shutdown(sockets[i].fd, SHUT_RDWR);
 823                                         close(sockets[i].fd);
 824                                         sockets[i].type = AUTH_UNUSED;
 825                                         buffer_free(&sockets[i].input);
 826                                         buffer_free(&sockets[i].output);
 827                                         buffer_free(&sockets[i].request);
 828                                         break;
 829                                 }
 830                                 buffer_append(&sockets[i].input, buf, len);
 831                                 process_message(&sockets[i]);
 832                         }
 833                         break;
 834                 default:
 835                         fatal("Unknown type %d", sockets[i].type);
 836                 }
 837 }
 838
 839 static void
 840 cleanup_socket(void *p)
 841 {
 842         if (socket_name[0])
 843                 unlink(socket_name);
 844         if (socket_dir[0])
 845                 rmdir(socket_dir);
 846 }
 847
 848 static void
 849 cleanup_exit(int i)
 850 {
 851         cleanup_socket(NULL);
 852         exit(i);
 853 }
 854
 855 static void
 856 cleanup_handler(int sig)
 857 {
 858         cleanup_socket(NULL);
 859         _exit(2);
 860 }
 861
 862 static void
 863 check_parent_exists(int sig)
 864 {
 865         int save_errno = errno;
 866
 867         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 868                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 869                 cleanup_handler(sig); /* safe */
 870         }
 871         signal(SIGALRM, check_parent_exists);
 872         alarm(10);
 873         errno = save_errno;
 874 }
 875
 876 static void
 877 usage(void)
 878 {
 879         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 880             __progname);
 881         fprintf(stderr, "Options:\n");
 882         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 883         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 884         fprintf(stderr, "  -k          Kill the current agent.\n");
 885         fprintf(stderr, "  -d          Debug mode.\n");
 886         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 887         exit(1);
 888 }
 889
 890 int
 891 main(int ac, char **av)
 892 {
 893         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 894         struct sockaddr_un sunaddr;
 895 #ifdef HAVE_SETRLIMIT
 896         struct rlimit rlim;
 897 #endif
 898 #ifdef HAVE_CYGWIN
 899         int prev_mask;
 900 #endif
 901         pid_t pid;
 902         char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
 903         char *agentsocket = NULL;
 904         extern int optind;
 905         fd_set *readsetp = NULL, *writesetp = NULL;
 906
 907         SSLeay_add_all_algorithms();
 908
 909         __progname = get_progname(av[0]);
 910         init_rng();
 911         seed_rng();
 912
 913 #ifdef __GNU_LIBRARY__
 914         while ((ch = getopt(ac, av, "+cdksa:")) != -1) {
 915 #else /* __GNU_LIBRARY__ */
 916         while ((ch = getopt(ac, av, "cdksa:")) != -1) {
 917 #endif /* __GNU_LIBRARY__ */
 918                 switch (ch) {
 919                 case 'c':
 920                         if (s_flag)
 921                                 usage();
 922                         c_flag++;
 923                         break;
 924                 case 'k':
 925                         k_flag++;
 926                         break;
 927                 case 's':
 928                         if (c_flag)
 929                                 usage();
 930                         s_flag++;
 931                         break;
 932                 case 'd':
 933                         if (d_flag)
 934                                 usage();
 935                         d_flag++;
 936                         break;
 937                 case 'a':
 938                         agentsocket = optarg;
 939                         break;
 940                 default:
 941                         usage();
 942                 }
 943         }
 944         ac -= optind;
 945         av += optind;
 946
 947         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
 948                 usage();
 949
 950         if (ac == 0 && !c_flag && !s_flag) {
 951                 shell = getenv("SHELL");
 952                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
 953                         c_flag = 1;
 954         }
 955         if (k_flag) {
 956                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
 957                 if (pidstr == NULL) {
 958                         fprintf(stderr, "%s not set, cannot kill agent\n",
 959                             SSH_AGENTPID_ENV_NAME);
 960                         exit(1);
 961                 }
 962                 pid = atoi(pidstr);
 963                 if (pid < 1) {
 964                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
 965                             SSH_AGENTPID_ENV_NAME, pidstr);
 966                         exit(1);
 967                 }
 968                 if (kill(pid, SIGTERM) == -1) {
 969                         perror("kill");
 970                         exit(1);
 971                 }
 972                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
 973                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
 974                 printf(format, SSH_AGENTPID_ENV_NAME);
 975                 printf("echo Agent pid %d killed;\n", pid);
 976                 exit(0);
 977         }
 978         parent_pid = getpid();
 979
 980         if (agentsocket == NULL) {
 981                 /* Create private directory for agent socket */
 982                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
 983                 if (mkdtemp(socket_dir) == NULL) {
 984                         perror("mkdtemp: private socket dir");
 985                         exit(1);
 986                 }
 987                 snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
 988                     parent_pid);
 989         } else {
 990                 /* Try to use specified agent socket */
 991                 socket_dir[0] = '\0';
 992                 strlcpy(socket_name, agentsocket, sizeof socket_name);
 993         }
 994
 995         /*
 996          * Create socket early so it will exist before command gets run from
 997          * the parent.
 998          */
 999         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1000         if (sock < 0) {
1001                 perror("socket");
1002                 cleanup_exit(1);
1003         }
1004         memset(&sunaddr, 0, sizeof(sunaddr));
1005         sunaddr.sun_family = AF_UNIX;
1006         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1007 #ifdef HAVE_CYGWIN
1008         prev_mask = umask(0177);
1009 #endif
1010         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1011                 perror("bind");
1012 #ifdef HAVE_CYGWIN
1013                 umask(prev_mask);
1014 #endif
1015                 cleanup_exit(1);
1016         }
1017 #ifdef HAVE_CYGWIN
1018         umask(prev_mask);
1019 #endif
1020         if (listen(sock, 5) < 0) {
1021                 perror("listen");
1022                 cleanup_exit(1);
1023         }
1024
1025         /*
1026          * Fork, and have the parent execute the command, if any, or present
1027          * the socket data.  The child continues as the authentication agent.
1028          */
1029         if (d_flag) {
1030                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1031                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1032                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1033                     SSH_AUTHSOCKET_ENV_NAME);
1034                 printf("echo Agent pid %d;\n", parent_pid);
1035                 goto skip;
1036         }
1037         pid = fork();
1038         if (pid == -1) {
1039                 perror("fork");
1040                 cleanup_exit(1);
1041         }
1042         if (pid != 0) {         /* Parent - execute the given command. */
1043                 close(sock);
1044                 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
1045                 if (ac == 0) {
1046                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1047                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1048                             SSH_AUTHSOCKET_ENV_NAME);
1049                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1050                             SSH_AGENTPID_ENV_NAME);
1051                         printf("echo Agent pid %d;\n", pid);
1052                         exit(0);
1053                 }
1054                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1055                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1056                         perror("setenv");
1057                         exit(1);
1058                 }
1059                 execvp(av[0], av);
1060                 perror(av[0]);
1061                 exit(1);
1062         }
1063         /* child */
1064         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1065
1066         if (setsid() == -1) {
1067                 error("setsid: %s", strerror(errno));
1068                 cleanup_exit(1);
1069         }
1070
1071         (void)chdir("/");
1072         close(0);
1073         close(1);
1074         close(2);
1075
1076 #ifdef HAVE_SETRLIMIT
1077         /* deny core dumps, since memory contains unencrypted private keys */
1078         rlim.rlim_cur = rlim.rlim_max = 0;
1079         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1080                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1081                 cleanup_exit(1);
1082         }
1083 #endif
1084
1085 skip:
1086         fatal_add_cleanup(cleanup_socket, NULL);
1087         new_socket(AUTH_SOCKET, sock);
1088         if (ac > 0) {
1089                 signal(SIGALRM, check_parent_exists);
1090                 alarm(10);
1091         }
1092         idtab_init();
1093         if (!d_flag)
1094                 signal(SIGINT, SIG_IGN);
1095         signal(SIGPIPE, SIG_IGN);
1096         signal(SIGHUP, cleanup_handler);
1097         signal(SIGTERM, cleanup_handler);
1098         nalloc = 0;
1099
1100         while (1) {
1101                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1102                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1103                         if (errno == EINTR)
1104                                 continue;
1105                         fatal("select: %s", strerror(errno));
1106                 }
1107                 after_select(readsetp, writesetp);
1108         }
1109         /* NOTREACHED */
1110 }