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/sys-queue.h"
  38 RCSID("$OpenBSD: ssh-agent.c,v 1.104 2002/09/12 19:11:52 stevesk 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 close_socket(SocketEntry *e)
 111 {
 112         close(e->fd);
 113         e->fd = -1;
 114         e->type = AUTH_UNUSED;
 115         buffer_free(&e->input);
 116         buffer_free(&e->output);
 117         buffer_free(&e->request);
 118 }
 119
 120 static void
 121 idtab_init(void)
 122 {
 123         int i;
 124
 125         for (i = 0; i <=2; i++) {
 126                 TAILQ_INIT(&idtable[i].idlist);
 127                 idtable[i].nentries = 0;
 128         }
 129 }
 130
 131 /* return private key table for requested protocol version */
 132 static Idtab *
 133 idtab_lookup(int version)
 134 {
 135         if (version < 1 || version > 2)
 136                 fatal("internal error, bad protocol version %d", version);
 137         return &idtable[version];
 138 }
 139
 140 static void
 141 free_identity(Identity *id)
 142 {
 143         key_free(id->key);
 144         xfree(id->comment);
 145         xfree(id);
 146 }
 147
 148 /* return matching private key for given public key */
 149 static Identity *
 150 lookup_identity(Key *key, int version)
 151 {
 152         Identity *id;
 153
 154         Idtab *tab = idtab_lookup(version);
 155         TAILQ_FOREACH(id, &tab->idlist, next) {
 156                 if (key_equal(key, id->key))
 157                         return (id);
 158         }
 159         return (NULL);
 160 }
 161
 162 /* send list of supported public keys to 'client' */
 163 static void
 164 process_request_identities(SocketEntry *e, int version)
 165 {
 166         Idtab *tab = idtab_lookup(version);
 167         Identity *id;
 168         Buffer msg;
 169
 170         buffer_init(&msg);
 171         buffer_put_char(&msg, (version == 1) ?
 172             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 173         buffer_put_int(&msg, tab->nentries);
 174         TAILQ_FOREACH(id, &tab->idlist, next) {
 175                 if (id->key->type == KEY_RSA1) {
 176                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 177                         buffer_put_bignum(&msg, id->key->rsa->e);
 178                         buffer_put_bignum(&msg, id->key->rsa->n);
 179                 } else {
 180                         u_char *blob;
 181                         u_int blen;
 182                         key_to_blob(id->key, &blob, &blen);
 183                         buffer_put_string(&msg, blob, blen);
 184                         xfree(blob);
 185                 }
 186                 buffer_put_cstring(&msg, id->comment);
 187         }
 188         buffer_put_int(&e->output, buffer_len(&msg));
 189         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 190         buffer_free(&msg);
 191 }
 192
 193 /* ssh1 only */
 194 static void
 195 process_authentication_challenge1(SocketEntry *e)
 196 {
 197         u_char buf[32], mdbuf[16], session_id[16];
 198         u_int response_type;
 199         BIGNUM *challenge;
 200         Identity *id;
 201         int i, len;
 202         Buffer msg;
 203         MD5_CTX md;
 204         Key *key;
 205
 206         buffer_init(&msg);
 207         key = key_new(KEY_RSA1);
 208         if ((challenge = BN_new()) == NULL)
 209                 fatal("process_authentication_challenge1: BN_new failed");
 210
 211         (void) buffer_get_int(&e->request);                     /* ignored */
 212         buffer_get_bignum(&e->request, key->rsa->e);
 213         buffer_get_bignum(&e->request, key->rsa->n);
 214         buffer_get_bignum(&e->request, challenge);
 215
 216         /* Only protocol 1.1 is supported */
 217         if (buffer_len(&e->request) == 0)
 218                 goto failure;
 219         buffer_get(&e->request, session_id, 16);
 220         response_type = buffer_get_int(&e->request);
 221         if (response_type != 1)
 222                 goto failure;
 223
 224         id = lookup_identity(key, 1);
 225         if (id != NULL) {
 226                 Key *private = id->key;
 227                 /* Decrypt the challenge using the private key. */
 228                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 229                         goto failure;
 230
 231                 /* The response is MD5 of decrypted challenge plus session id. */
 232                 len = BN_num_bytes(challenge);
 233                 if (len <= 0 || len > 32) {
 234                         log("process_authentication_challenge: bad challenge length %d", len);
 235                         goto failure;
 236                 }
 237                 memset(buf, 0, 32);
 238                 BN_bn2bin(challenge, buf + 32 - len);
 239                 MD5_Init(&md);
 240                 MD5_Update(&md, buf, 32);
 241                 MD5_Update(&md, session_id, 16);
 242                 MD5_Final(mdbuf, &md);
 243
 244                 /* Send the response. */
 245                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 246                 for (i = 0; i < 16; i++)
 247                         buffer_put_char(&msg, mdbuf[i]);
 248                 goto send;
 249         }
 250
 251 failure:
 252         /* Unknown identity or protocol error.  Send failure. */
 253         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 254 send:
 255         buffer_put_int(&e->output, buffer_len(&msg));
 256         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 257         key_free(key);
 258         BN_clear_free(challenge);
 259         buffer_free(&msg);
 260 }
 261
 262 /* ssh2 only */
 263 static void
 264 process_sign_request2(SocketEntry *e)
 265 {
 266         u_char *blob, *data, *signature = NULL;
 267         u_int blen, dlen, slen = 0;
 268         extern int datafellows;
 269         int ok = -1, flags;
 270         Buffer msg;
 271         Key *key;
 272
 273         datafellows = 0;
 274
 275         blob = buffer_get_string(&e->request, &blen);
 276         data = buffer_get_string(&e->request, &dlen);
 277
 278         flags = buffer_get_int(&e->request);
 279         if (flags & SSH_AGENT_OLD_SIGNATURE)
 280                 datafellows = SSH_BUG_SIGBLOB;
 281
 282         key = key_from_blob(blob, blen);
 283         if (key != NULL) {
 284                 Identity *id = lookup_identity(key, 2);
 285                 if (id != NULL)
 286                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 287         }
 288         key_free(key);
 289         buffer_init(&msg);
 290         if (ok == 0) {
 291                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 292                 buffer_put_string(&msg, signature, slen);
 293         } else {
 294                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 295         }
 296         buffer_put_int(&e->output, buffer_len(&msg));
 297         buffer_append(&e->output, buffer_ptr(&msg),
 298             buffer_len(&msg));
 299         buffer_free(&msg);
 300         xfree(data);
 301         xfree(blob);
 302         if (signature != NULL)
 303                 xfree(signature);
 304 }
 305
 306 /* shared */
 307 static void
 308 process_remove_identity(SocketEntry *e, int version)
 309 {
 310         u_int blen, bits;
 311         int success = 0;
 312         Key *key = NULL;
 313         u_char *blob;
 314
 315         switch (version) {
 316         case 1:
 317                 key = key_new(KEY_RSA1);
 318                 bits = buffer_get_int(&e->request);
 319                 buffer_get_bignum(&e->request, key->rsa->e);
 320                 buffer_get_bignum(&e->request, key->rsa->n);
 321
 322                 if (bits != key_size(key))
 323                         log("Warning: identity keysize mismatch: actual %u, announced %u",
 324                             key_size(key), bits);
 325                 break;
 326         case 2:
 327                 blob = buffer_get_string(&e->request, &blen);
 328                 key = key_from_blob(blob, blen);
 329                 xfree(blob);
 330                 break;
 331         }
 332         if (key != NULL) {
 333                 Identity *id = lookup_identity(key, version);
 334                 if (id != NULL) {
 335                         /*
 336                          * We have this key.  Free the old key.  Since we
 337                          * don\'t want to leave empty slots in the middle of
 338                          * the array, we actually free the key there and move
 339                          * all the entries between the empty slot and the end
 340                          * of the array.
 341                          */
 342                         Idtab *tab = idtab_lookup(version);
 343                         if (tab->nentries < 1)
 344                                 fatal("process_remove_identity: "
 345                                     "internal error: tab->nentries %d",
 346                                     tab->nentries);
 347                         TAILQ_REMOVE(&tab->idlist, id, next);
 348                         free_identity(id);
 349                         tab->nentries--;
 350                         success = 1;
 351                 }
 352                 key_free(key);
 353         }
 354         buffer_put_int(&e->output, 1);
 355         buffer_put_char(&e->output,
 356             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 357 }
 358
 359 static void
 360 process_remove_all_identities(SocketEntry *e, int version)
 361 {
 362         Idtab *tab = idtab_lookup(version);
 363         Identity *id;
 364
 365         /* Loop over all identities and clear the keys. */
 366         for (id = TAILQ_FIRST(&tab->idlist); id;
 367             id = TAILQ_FIRST(&tab->idlist)) {
 368                 TAILQ_REMOVE(&tab->idlist, id, next);
 369                 free_identity(id);
 370         }
 371
 372         /* Mark that there are no identities. */
 373         tab->nentries = 0;
 374
 375         /* Send success. */
 376         buffer_put_int(&e->output, 1);
 377         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 378 }
 379
 380 static void
 381 reaper(void)
 382 {
 383         u_int now = time(NULL);
 384         Identity *id, *nxt;
 385         int version;
 386         Idtab *tab;
 387
 388         for (version = 1; version < 3; version++) {
 389                 tab = idtab_lookup(version);
 390                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 391                         nxt = TAILQ_NEXT(id, next);
 392                         if (id->death != 0 && now >= id->death) {
 393                                 TAILQ_REMOVE(&tab->idlist, id, next);
 394                                 free_identity(id);
 395                                 tab->nentries--;
 396                         }
 397                 }
 398         }
 399 }
 400
 401 static void
 402 process_add_identity(SocketEntry *e, int version)
 403 {
 404         Idtab *tab = idtab_lookup(version);
 405         int type, success = 0, death = 0;
 406         char *type_name, *comment;
 407         Key *k = NULL;
 408
 409         switch (version) {
 410         case 1:
 411                 k = key_new_private(KEY_RSA1);
 412                 (void) buffer_get_int(&e->request);             /* ignored */
 413                 buffer_get_bignum(&e->request, k->rsa->n);
 414                 buffer_get_bignum(&e->request, k->rsa->e);
 415                 buffer_get_bignum(&e->request, k->rsa->d);
 416                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 417
 418                 /* SSH and SSL have p and q swapped */
 419                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 420                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 421
 422                 /* Generate additional parameters */
 423                 rsa_generate_additional_parameters(k->rsa);
 424                 break;
 425         case 2:
 426                 type_name = buffer_get_string(&e->request, NULL);
 427                 type = key_type_from_name(type_name);
 428                 xfree(type_name);
 429                 switch (type) {
 430                 case KEY_DSA:
 431                         k = key_new_private(type);
 432                         buffer_get_bignum2(&e->request, k->dsa->p);
 433                         buffer_get_bignum2(&e->request, k->dsa->q);
 434                         buffer_get_bignum2(&e->request, k->dsa->g);
 435                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 436                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 437                         break;
 438                 case KEY_RSA:
 439                         k = key_new_private(type);
 440                         buffer_get_bignum2(&e->request, k->rsa->n);
 441                         buffer_get_bignum2(&e->request, k->rsa->e);
 442                         buffer_get_bignum2(&e->request, k->rsa->d);
 443                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 444                         buffer_get_bignum2(&e->request, k->rsa->p);
 445                         buffer_get_bignum2(&e->request, k->rsa->q);
 446
 447                         /* Generate additional parameters */
 448                         rsa_generate_additional_parameters(k->rsa);
 449                         break;
 450                 default:
 451                         buffer_clear(&e->request);
 452                         goto send;
 453                 }
 454                 break;
 455         }
 456         comment = buffer_get_string(&e->request, NULL);
 457         if (k == NULL) {
 458                 xfree(comment);
 459                 goto send;
 460         }
 461         success = 1;
 462         while (buffer_len(&e->request)) {
 463                 switch (buffer_get_char(&e->request)) {
 464                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 465                         death = time(NULL) + buffer_get_int(&e->request);
 466                         break;
 467                 default:
 468                         break;
 469                 }
 470         }
 471         if (lookup_identity(k, version) == NULL) {
 472                 Identity *id = xmalloc(sizeof(Identity));
 473                 id->key = k;
 474                 id->comment = comment;
 475                 id->death = death;
 476                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 477                 /* Increment the number of identities. */
 478                 tab->nentries++;
 479         } else {
 480                 key_free(k);
 481                 xfree(comment);
 482         }
 483 send:
 484         buffer_put_int(&e->output, 1);
 485         buffer_put_char(&e->output,
 486             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 487 }
 488
 489 /* XXX todo: encrypt sensitive data with passphrase */
 490 static void
 491 process_lock_agent(SocketEntry *e, int lock)
 492 {
 493         int success = 0;
 494         char *passwd;
 495
 496         passwd = buffer_get_string(&e->request, NULL);
 497         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 498                 locked = 0;
 499                 memset(lock_passwd, 0, strlen(lock_passwd));
 500                 xfree(lock_passwd);
 501                 lock_passwd = NULL;
 502                 success = 1;
 503         } else if (!locked && lock) {
 504                 locked = 1;
 505                 lock_passwd = xstrdup(passwd);
 506                 success = 1;
 507         }
 508         memset(passwd, 0, strlen(passwd));
 509         xfree(passwd);
 510
 511         buffer_put_int(&e->output, 1);
 512         buffer_put_char(&e->output,
 513             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 514 }
 515
 516 static void
 517 no_identities(SocketEntry *e, u_int type)
 518 {
 519         Buffer msg;
 520
 521         buffer_init(&msg);
 522         buffer_put_char(&msg,
 523             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 524             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 525         buffer_put_int(&msg, 0);
 526         buffer_put_int(&e->output, buffer_len(&msg));
 527         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 528         buffer_free(&msg);
 529 }
 530
 531 #ifdef SMARTCARD
 532 static void
 533 process_add_smartcard_key (SocketEntry *e)
 534 {
 535         char *sc_reader_id = NULL, *pin;
 536         int i, version, success = 0;
 537         Key **keys, *k;
 538         Identity *id;
 539         Idtab *tab;
 540
 541         sc_reader_id = buffer_get_string(&e->request, NULL);
 542         pin = buffer_get_string(&e->request, NULL);
 543         keys = sc_get_keys(sc_reader_id, pin);
 544         xfree(sc_reader_id);
 545         xfree(pin);
 546
 547         if (keys == NULL || keys[0] == NULL) {
 548                 error("sc_get_keys failed");
 549                 goto send;
 550         }
 551         for (i = 0; keys[i] != NULL; i++) {
 552                 k = keys[i];
 553                 version = k->type == KEY_RSA1 ? 1 : 2;
 554                 tab = idtab_lookup(version);
 555                 if (lookup_identity(k, version) == NULL) {
 556                         id = xmalloc(sizeof(Identity));
 557                         id->key = k;
 558                         id->comment = xstrdup("smartcard key");
 559                         id->death = 0;
 560                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 561                         tab->nentries++;
 562                         success = 1;
 563                 } else {
 564                         key_free(k);
 565                 }
 566                 keys[i] = NULL;
 567         }
 568         xfree(keys);
 569 send:
 570         buffer_put_int(&e->output, 1);
 571         buffer_put_char(&e->output,
 572             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 573 }
 574
 575 static void
 576 process_remove_smartcard_key(SocketEntry *e)
 577 {
 578         char *sc_reader_id = NULL, *pin;
 579         int i, version, success = 0;
 580         Key **keys, *k = NULL;
 581         Identity *id;
 582         Idtab *tab;
 583
 584         sc_reader_id = buffer_get_string(&e->request, NULL);
 585         pin = buffer_get_string(&e->request, NULL);
 586         keys = sc_get_keys(sc_reader_id, pin);
 587         xfree(sc_reader_id);
 588         xfree(pin);
 589
 590         if (keys == NULL || keys[0] == NULL) {
 591                 error("sc_get_keys failed");
 592                 goto send;
 593         }
 594         for (i = 0; keys[i] != NULL; i++) {
 595                 k = keys[i];
 596                 version = k->type == KEY_RSA1 ? 1 : 2;
 597                 if ((id = lookup_identity(k, version)) != NULL) {
 598                         tab = idtab_lookup(version);
 599                         TAILQ_REMOVE(&tab->idlist, id, next);
 600                         tab->nentries--;
 601                         free_identity(id);
 602                         success = 1;
 603                 }
 604                 key_free(k);
 605                 keys[i] = NULL;
 606         }
 607         xfree(keys);
 608 send:
 609         buffer_put_int(&e->output, 1);
 610         buffer_put_char(&e->output,
 611             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 612 }
 613 #endif /* SMARTCARD */
 614
 615 /* dispatch incoming messages */
 616
 617 static void
 618 process_message(SocketEntry *e)
 619 {
 620         u_int msg_len, type;
 621         u_char *cp;
 622
 623         /* kill dead keys */
 624         reaper();
 625
 626         if (buffer_len(&e->input) < 5)
 627                 return;         /* Incomplete message. */
 628         cp = buffer_ptr(&e->input);
 629         msg_len = GET_32BIT(cp);
 630         if (msg_len > 256 * 1024) {
 631                 close_socket(e);
 632                 return;
 633         }
 634         if (buffer_len(&e->input) < msg_len + 4)
 635                 return;
 636
 637         /* move the current input to e->request */
 638         buffer_consume(&e->input, 4);
 639         buffer_clear(&e->request);
 640         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 641         buffer_consume(&e->input, msg_len);
 642         type = buffer_get_char(&e->request);
 643
 644         /* check wheter agent is locked */
 645         if (locked && type != SSH_AGENTC_UNLOCK) {
 646                 buffer_clear(&e->request);
 647                 switch (type) {
 648                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 649                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 650                         /* send empty lists */
 651                         no_identities(e, type);
 652                         break;
 653                 default:
 654                         /* send a fail message for all other request types */
 655                         buffer_put_int(&e->output, 1);
 656                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 657                 }
 658                 return;
 659         }
 660
 661         debug("type %d", type);
 662         switch (type) {
 663         case SSH_AGENTC_LOCK:
 664         case SSH_AGENTC_UNLOCK:
 665                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 666                 break;
 667         /* ssh1 */
 668         case SSH_AGENTC_RSA_CHALLENGE:
 669                 process_authentication_challenge1(e);
 670                 break;
 671         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 672                 process_request_identities(e, 1);
 673                 break;
 674         case SSH_AGENTC_ADD_RSA_IDENTITY:
 675         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 676                 process_add_identity(e, 1);
 677                 break;
 678         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 679                 process_remove_identity(e, 1);
 680                 break;
 681         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 682                 process_remove_all_identities(e, 1);
 683                 break;
 684         /* ssh2 */
 685         case SSH2_AGENTC_SIGN_REQUEST:
 686                 process_sign_request2(e);
 687                 break;
 688         case SSH2_AGENTC_REQUEST_IDENTITIES:
 689                 process_request_identities(e, 2);
 690                 break;
 691         case SSH2_AGENTC_ADD_IDENTITY:
 692         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 693                 process_add_identity(e, 2);
 694                 break;
 695         case SSH2_AGENTC_REMOVE_IDENTITY:
 696                 process_remove_identity(e, 2);
 697                 break;
 698         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 699                 process_remove_all_identities(e, 2);
 700                 break;
 701 #ifdef SMARTCARD
 702         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 703                 process_add_smartcard_key(e);
 704                 break;
 705         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 706                 process_remove_smartcard_key(e);
 707                 break;
 708 #endif /* SMARTCARD */
 709         default:
 710                 /* Unknown message.  Respond with failure. */
 711                 error("Unknown message %d", type);
 712                 buffer_clear(&e->request);
 713                 buffer_put_int(&e->output, 1);
 714                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 715                 break;
 716         }
 717 }
 718
 719 static void
 720 new_socket(sock_type type, int fd)
 721 {
 722         u_int i, old_alloc;
 723
 724         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 725                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 726
 727         if (fd > max_fd)
 728                 max_fd = fd;
 729
 730         for (i = 0; i < sockets_alloc; i++)
 731                 if (sockets[i].type == AUTH_UNUSED) {
 732                         sockets[i].fd = fd;
 733                         sockets[i].type = type;
 734                         buffer_init(&sockets[i].input);
 735                         buffer_init(&sockets[i].output);
 736                         buffer_init(&sockets[i].request);
 737                         return;
 738                 }
 739         old_alloc = sockets_alloc;
 740         sockets_alloc += 10;
 741         if (sockets)
 742                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 743         else
 744                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 745         for (i = old_alloc; i < sockets_alloc; i++)
 746                 sockets[i].type = AUTH_UNUSED;
 747         sockets[old_alloc].type = type;
 748         sockets[old_alloc].fd = fd;
 749         buffer_init(&sockets[old_alloc].input);
 750         buffer_init(&sockets[old_alloc].output);
 751         buffer_init(&sockets[old_alloc].request);
 752 }
 753
 754 static int
 755 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 756 {
 757         u_int i, sz;
 758         int n = 0;
 759
 760         for (i = 0; i < sockets_alloc; i++) {
 761                 switch (sockets[i].type) {
 762                 case AUTH_SOCKET:
 763                 case AUTH_CONNECTION:
 764                         n = MAX(n, sockets[i].fd);
 765                         break;
 766                 case AUTH_UNUSED:
 767                         break;
 768                 default:
 769                         fatal("Unknown socket type %d", sockets[i].type);
 770                         break;
 771                 }
 772         }
 773
 774         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 775         if (*fdrp == NULL || sz > *nallocp) {
 776                 if (*fdrp)
 777                         xfree(*fdrp);
 778                 if (*fdwp)
 779                         xfree(*fdwp);
 780                 *fdrp = xmalloc(sz);
 781                 *fdwp = xmalloc(sz);
 782                 *nallocp = sz;
 783         }
 784         if (n < *fdl)
 785                 debug("XXX shrink: %d < %d", n, *fdl);
 786         *fdl = n;
 787         memset(*fdrp, 0, sz);
 788         memset(*fdwp, 0, sz);
 789
 790         for (i = 0; i < sockets_alloc; i++) {
 791                 switch (sockets[i].type) {
 792                 case AUTH_SOCKET:
 793                 case AUTH_CONNECTION:
 794                         FD_SET(sockets[i].fd, *fdrp);
 795                         if (buffer_len(&sockets[i].output) > 0)
 796                                 FD_SET(sockets[i].fd, *fdwp);
 797                         break;
 798                 default:
 799                         break;
 800                 }
 801         }
 802         return (1);
 803 }
 804
 805 static void
 806 after_select(fd_set *readset, fd_set *writeset)
 807 {
 808         struct sockaddr_un sunaddr;
 809         socklen_t slen;
 810         char buf[1024];
 811         int len, sock;
 812         u_int i;
 813         uid_t euid;
 814         gid_t egid;
 815
 816         for (i = 0; i < sockets_alloc; i++)
 817                 switch (sockets[i].type) {
 818                 case AUTH_UNUSED:
 819                         break;
 820                 case AUTH_SOCKET:
 821                         if (FD_ISSET(sockets[i].fd, readset)) {
 822                                 slen = sizeof(sunaddr);
 823                                 sock = accept(sockets[i].fd,
 824                                     (struct sockaddr *) &sunaddr, &slen);
 825                                 if (sock < 0) {
 826                                         error("accept from AUTH_SOCKET: %s",
 827                                             strerror(errno));
 828                                         break;
 829                                 }
 830                                 if (getpeereid(sock, &euid, &egid) < 0) {
 831                                         error("getpeereid %d failed: %s",
 832                                             sock, strerror(errno));
 833                                         close(sock);
 834                                         break;
 835                                 }
 836                                 if (getuid() != euid) {
 837                                         error("uid mismatch: "
 838                                             "peer euid %u != uid %u",
 839                                             (u_int) euid, (u_int) getuid());
 840                                         close(sock);
 841                                         break;
 842                                 }
 843                                 new_socket(AUTH_CONNECTION, sock);
 844                         }
 845                         break;
 846                 case AUTH_CONNECTION:
 847                         if (buffer_len(&sockets[i].output) > 0 &&
 848                             FD_ISSET(sockets[i].fd, writeset)) {
 849                                 do {
 850                                         len = write(sockets[i].fd,
 851                                             buffer_ptr(&sockets[i].output),
 852                                             buffer_len(&sockets[i].output));
 853                                         if (len == -1 && (errno == EAGAIN ||
 854                                             errno == EINTR))
 855                                                 continue;
 856                                         break;
 857                                 } while (1);
 858                                 if (len <= 0) {
 859                                         close_socket(&sockets[i]);
 860                                         break;
 861                                 }
 862                                 buffer_consume(&sockets[i].output, len);
 863                         }
 864                         if (FD_ISSET(sockets[i].fd, readset)) {
 865                                 do {
 866                                         len = read(sockets[i].fd, buf, sizeof(buf));
 867                                         if (len == -1 && (errno == EAGAIN ||
 868                                             errno == EINTR))
 869                                                 continue;
 870                                         break;
 871                                 } while (1);
 872                                 if (len <= 0) {
 873                                         close_socket(&sockets[i]);
 874                                         break;
 875                                 }
 876                                 buffer_append(&sockets[i].input, buf, len);
 877                                 process_message(&sockets[i]);
 878                         }
 879                         break;
 880                 default:
 881                         fatal("Unknown type %d", sockets[i].type);
 882                 }
 883 }
 884
 885 static void
 886 cleanup_socket(void *p)
 887 {
 888         if (socket_name[0])
 889                 unlink(socket_name);
 890         if (socket_dir[0])
 891                 rmdir(socket_dir);
 892 }
 893
 894 static void
 895 cleanup_exit(int i)
 896 {
 897         cleanup_socket(NULL);
 898         exit(i);
 899 }
 900
 901 static void
 902 cleanup_handler(int sig)
 903 {
 904         cleanup_socket(NULL);
 905         _exit(2);
 906 }
 907
 908 static void
 909 check_parent_exists(int sig)
 910 {
 911         int save_errno = errno;
 912
 913         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 914                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 915                 cleanup_handler(sig); /* safe */
 916         }
 917         signal(SIGALRM, check_parent_exists);
 918         alarm(10);
 919         errno = save_errno;
 920 }
 921
 922 static void
 923 usage(void)
 924 {
 925         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 926             __progname);
 927         fprintf(stderr, "Options:\n");
 928         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 929         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 930         fprintf(stderr, "  -k          Kill the current agent.\n");
 931         fprintf(stderr, "  -d          Debug mode.\n");
 932         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 933         exit(1);
 934 }
 935
 936 int
 937 main(int ac, char **av)
 938 {
 939         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 940         char *shell, *format, *pidstr, *agentsocket = NULL;
 941         fd_set *readsetp = NULL, *writesetp = NULL;
 942         struct sockaddr_un sunaddr;
 943 #ifdef HAVE_SETRLIMIT
 944         struct rlimit rlim;
 945 #endif
 946 #ifdef HAVE_CYGWIN
 947         int prev_mask;
 948 #endif
 949         extern int optind;
 950         extern char *optarg;
 951         pid_t pid;
 952         char pidstrbuf[1 + 3 * sizeof pid];
 953
 954         /* drop */
 955         setegid(getgid());
 956         setgid(getgid());
 957
 958         SSLeay_add_all_algorithms();
 959
 960         __progname = get_progname(av[0]);
 961         init_rng();
 962         seed_rng();
 963
 964         while ((ch = getopt(ac, av, "cdksa:")) != -1) {
 965                 switch (ch) {
 966                 case 'c':
 967                         if (s_flag)
 968                                 usage();
 969                         c_flag++;
 970                         break;
 971                 case 'k':
 972                         k_flag++;
 973                         break;
 974                 case 's':
 975                         if (c_flag)
 976                                 usage();
 977                         s_flag++;
 978                         break;
 979                 case 'd':
 980                         if (d_flag)
 981                                 usage();
 982                         d_flag++;
 983                         break;
 984                 case 'a':
 985                         agentsocket = optarg;
 986                         break;
 987                 default:
 988                         usage();
 989                 }
 990         }
 991         ac -= optind;
 992         av += optind;
 993
 994         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
 995                 usage();
 996
 997         if (ac == 0 && !c_flag && !s_flag) {
 998                 shell = getenv("SHELL");
 999                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1000                         c_flag = 1;
1001         }
1002         if (k_flag) {
1003                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1004                 if (pidstr == NULL) {
1005                         fprintf(stderr, "%s not set, cannot kill agent\n",
1006                             SSH_AGENTPID_ENV_NAME);
1007                         exit(1);
1008                 }
1009                 pid = atoi(pidstr);
1010                 if (pid < 1) {
1011                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
1012                             SSH_AGENTPID_ENV_NAME, pidstr);
1013                         exit(1);
1014                 }
1015                 if (kill(pid, SIGTERM) == -1) {
1016                         perror("kill");
1017                         exit(1);
1018                 }
1019                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1020                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1021                 printf(format, SSH_AGENTPID_ENV_NAME);
1022                 printf("echo Agent pid %ld killed;\n", (long)pid);
1023                 exit(0);
1024         }
1025         parent_pid = getpid();
1026
1027         if (agentsocket == NULL) {
1028                 /* Create private directory for agent socket */
1029                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
1030                 if (mkdtemp(socket_dir) == NULL) {
1031                         perror("mkdtemp: private socket dir");
1032                         exit(1);
1033                 }
1034                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1035                     (long)parent_pid);
1036         } else {
1037                 /* Try to use specified agent socket */
1038                 socket_dir[0] = '\0';
1039                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1040         }
1041
1042         /*
1043          * Create socket early so it will exist before command gets run from
1044          * the parent.
1045          */
1046         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1047         if (sock < 0) {
1048                 perror("socket");
1049                 cleanup_exit(1);
1050         }
1051         memset(&sunaddr, 0, sizeof(sunaddr));
1052         sunaddr.sun_family = AF_UNIX;
1053         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1054 #ifdef HAVE_CYGWIN
1055         prev_mask = umask(0177);
1056 #endif
1057         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1058                 perror("bind");
1059 #ifdef HAVE_CYGWIN
1060                 umask(prev_mask);
1061 #endif
1062                 cleanup_exit(1);
1063         }
1064 #ifdef HAVE_CYGWIN
1065         umask(prev_mask);
1066 #endif
1067         if (listen(sock, 128) < 0) {
1068                 perror("listen");
1069                 cleanup_exit(1);
1070         }
1071
1072         /*
1073          * Fork, and have the parent execute the command, if any, or present
1074          * the socket data.  The child continues as the authentication agent.
1075          */
1076         if (d_flag) {
1077                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1078                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1079                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1080                     SSH_AUTHSOCKET_ENV_NAME);
1081                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1082                 goto skip;
1083         }
1084         pid = fork();
1085         if (pid == -1) {
1086                 perror("fork");
1087                 cleanup_exit(1);
1088         }
1089         if (pid != 0) {         /* Parent - execute the given command. */
1090                 close(sock);
1091                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1092                 if (ac == 0) {
1093                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1094                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1095                             SSH_AUTHSOCKET_ENV_NAME);
1096                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1097                             SSH_AGENTPID_ENV_NAME);
1098                         printf("echo Agent pid %ld;\n", (long)pid);
1099                         exit(0);
1100                 }
1101                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1102                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1103                         perror("setenv");
1104                         exit(1);
1105                 }
1106                 execvp(av[0], av);
1107                 perror(av[0]);
1108                 exit(1);
1109         }
1110         /* child */
1111         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1112
1113         if (setsid() == -1) {
1114                 error("setsid: %s", strerror(errno));
1115                 cleanup_exit(1);
1116         }
1117
1118         (void)chdir("/");
1119         close(0);
1120         close(1);
1121         close(2);
1122
1123 #ifdef HAVE_SETRLIMIT
1124         /* deny core dumps, since memory contains unencrypted private keys */
1125         rlim.rlim_cur = rlim.rlim_max = 0;
1126         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1127                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1128                 cleanup_exit(1);
1129         }
1130 #endif
1131
1132 skip:
1133         fatal_add_cleanup(cleanup_socket, NULL);
1134         new_socket(AUTH_SOCKET, sock);
1135         if (ac > 0) {
1136                 signal(SIGALRM, check_parent_exists);
1137                 alarm(10);
1138         }
1139         idtab_init();
1140         if (!d_flag)
1141                 signal(SIGINT, SIG_IGN);
1142         signal(SIGPIPE, SIG_IGN);
1143         signal(SIGHUP, cleanup_handler);
1144         signal(SIGTERM, cleanup_handler);
1145         nalloc = 0;
1146
1147         while (1) {
1148                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1149                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1150                         if (errno == EINTR)
1151                                 continue;
1152                         fatal("select: %s", strerror(errno));
1153                 }
1154                 after_select(readsetp, writesetp);
1155         }
1156         /* NOTREACHED */
1157 }