ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.137 2006/03/30 09:58:16 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * The authentication agent program.
   7  *
   8  * As far as I am concerned, the code I have written for this software
   9  * can be used freely for any purpose.  Any derived versions of this
  10  * software must be clearly marked as such, and if the derived work is
  11  * incompatible with the protocol description in the RFC file, it must be
  12  * called by a name other than "ssh" or "Secure Shell".
  13  *
  14  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  15  *
  16  * Redistribution and use in source and binary forms, with or without
  17  * modification, are permitted provided that the following conditions
  18  * are met:
  19  * 1. Redistributions of source code must retain the above copyright
  20  *    notice, this list of conditions and the following disclaimer.
  21  * 2. Redistributions in binary form must reproduce the above copyright
  22  *    notice, this list of conditions and the following disclaimer in the
  23  *    documentation and/or other materials provided with the distribution.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  26  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  27  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  28  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  29  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  30  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  31  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  32  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  33  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  34  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  35  */
  36
  37 #include "includes.h"
  38
  39 #include <sys/types.h>
  40 #include <sys/stat.h>
  41 #ifdef HAVE_SYS_UN_H
  42 # include <sys/un.h>
  43 #endif
  44 #include "openbsd-compat/sys-queue.h"
  45 #include <sys/resource.h>
  46 #ifdef HAVE_PATHS_H
  47 # include <paths.h>
  48 #endif
  49 #include <signal.h>
  50
  51 #include <openssl/evp.h>
  52 #include <openssl/md5.h>
  53
  54 #include "ssh.h"
  55 #include "rsa.h"
  56 #include "buffer.h"
  57 #include "bufaux.h"
  58 #include "xmalloc.h"
  59 #include "key.h"
  60 #include "authfd.h"
  61 #include "compat.h"
  62 #include "log.h"
  63 #include "misc.h"
  64
  65 #ifdef SMARTCARD
  66 #include "scard.h"
  67 #endif
  68
  69 #if defined(HAVE_SYS_PRCTL_H)
  70 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  71 #endif
  72
  73 typedef enum {
  74         AUTH_UNUSED,
  75         AUTH_SOCKET,
  76         AUTH_CONNECTION
  77 } sock_type;
  78
  79 typedef struct {
  80         int fd;
  81         sock_type type;
  82         Buffer input;
  83         Buffer output;
  84         Buffer request;
  85 } SocketEntry;
  86
  87 u_int sockets_alloc = 0;
  88 SocketEntry *sockets = NULL;
  89
  90 typedef struct identity {
  91         TAILQ_ENTRY(identity) next;
  92         Key *key;
  93         char *comment;
  94         u_int death;
  95         u_int confirm;
  96 } Identity;
  97
  98 typedef struct {
  99         int nentries;
 100         TAILQ_HEAD(idqueue, identity) idlist;
 101 } Idtab;
 102
 103 /* private key table, one per protocol version */
 104 Idtab idtable[3];
 105
 106 int max_fd = 0;
 107
 108 /* pid of shell == parent of agent */
 109 pid_t parent_pid = -1;
 110
 111 /* pathname and directory for AUTH_SOCKET */
 112 char socket_name[MAXPATHLEN];
 113 char socket_dir[MAXPATHLEN];
 114
 115 /* locking */
 116 int locked = 0;
 117 char *lock_passwd = NULL;
 118
 119 extern char *__progname;
 120
 121 /* Default lifetime (0 == forever) */
 122 static int lifetime = 0;
 123
 124 static void
 125 close_socket(SocketEntry *e)
 126 {
 127         close(e->fd);
 128         e->fd = -1;
 129         e->type = AUTH_UNUSED;
 130         buffer_free(&e->input);
 131         buffer_free(&e->output);
 132         buffer_free(&e->request);
 133 }
 134
 135 static void
 136 idtab_init(void)
 137 {
 138         int i;
 139
 140         for (i = 0; i <=2; i++) {
 141                 TAILQ_INIT(&idtable[i].idlist);
 142                 idtable[i].nentries = 0;
 143         }
 144 }
 145
 146 /* return private key table for requested protocol version */
 147 static Idtab *
 148 idtab_lookup(int version)
 149 {
 150         if (version < 1 || version > 2)
 151                 fatal("internal error, bad protocol version %d", version);
 152         return &idtable[version];
 153 }
 154
 155 static void
 156 free_identity(Identity *id)
 157 {
 158         key_free(id->key);
 159         xfree(id->comment);
 160         xfree(id);
 161 }
 162
 163 /* return matching private key for given public key */
 164 static Identity *
 165 lookup_identity(Key *key, int version)
 166 {
 167         Identity *id;
 168
 169         Idtab *tab = idtab_lookup(version);
 170         TAILQ_FOREACH(id, &tab->idlist, next) {
 171                 if (key_equal(key, id->key))
 172                         return (id);
 173         }
 174         return (NULL);
 175 }
 176
 177 /* Check confirmation of keysign request */
 178 static int
 179 confirm_key(Identity *id)
 180 {
 181         char *p;
 182         int ret = -1;
 183
 184         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 185         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 186             id->comment, p))
 187                 ret = 0;
 188         xfree(p);
 189
 190         return (ret);
 191 }
 192
 193 /* send list of supported public keys to 'client' */
 194 static void
 195 process_request_identities(SocketEntry *e, int version)
 196 {
 197         Idtab *tab = idtab_lookup(version);
 198         Identity *id;
 199         Buffer msg;
 200
 201         buffer_init(&msg);
 202         buffer_put_char(&msg, (version == 1) ?
 203             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 204         buffer_put_int(&msg, tab->nentries);
 205         TAILQ_FOREACH(id, &tab->idlist, next) {
 206                 if (id->key->type == KEY_RSA1) {
 207                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 208                         buffer_put_bignum(&msg, id->key->rsa->e);
 209                         buffer_put_bignum(&msg, id->key->rsa->n);
 210                 } else {
 211                         u_char *blob;
 212                         u_int blen;
 213                         key_to_blob(id->key, &blob, &blen);
 214                         buffer_put_string(&msg, blob, blen);
 215                         xfree(blob);
 216                 }
 217                 buffer_put_cstring(&msg, id->comment);
 218         }
 219         buffer_put_int(&e->output, buffer_len(&msg));
 220         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 221         buffer_free(&msg);
 222 }
 223
 224 /* ssh1 only */
 225 static void
 226 process_authentication_challenge1(SocketEntry *e)
 227 {
 228         u_char buf[32], mdbuf[16], session_id[16];
 229         u_int response_type;
 230         BIGNUM *challenge;
 231         Identity *id;
 232         int i, len;
 233         Buffer msg;
 234         MD5_CTX md;
 235         Key *key;
 236
 237         buffer_init(&msg);
 238         key = key_new(KEY_RSA1);
 239         if ((challenge = BN_new()) == NULL)
 240                 fatal("process_authentication_challenge1: BN_new failed");
 241
 242         (void) buffer_get_int(&e->request);                     /* ignored */
 243         buffer_get_bignum(&e->request, key->rsa->e);
 244         buffer_get_bignum(&e->request, key->rsa->n);
 245         buffer_get_bignum(&e->request, challenge);
 246
 247         /* Only protocol 1.1 is supported */
 248         if (buffer_len(&e->request) == 0)
 249                 goto failure;
 250         buffer_get(&e->request, session_id, 16);
 251         response_type = buffer_get_int(&e->request);
 252         if (response_type != 1)
 253                 goto failure;
 254
 255         id = lookup_identity(key, 1);
 256         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 257                 Key *private = id->key;
 258                 /* Decrypt the challenge using the private key. */
 259                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 260                         goto failure;
 261
 262                 /* The response is MD5 of decrypted challenge plus session id. */
 263                 len = BN_num_bytes(challenge);
 264                 if (len <= 0 || len > 32) {
 265                         logit("process_authentication_challenge: bad challenge length %d", len);
 266                         goto failure;
 267                 }
 268                 memset(buf, 0, 32);
 269                 BN_bn2bin(challenge, buf + 32 - len);
 270                 MD5_Init(&md);
 271                 MD5_Update(&md, buf, 32);
 272                 MD5_Update(&md, session_id, 16);
 273                 MD5_Final(mdbuf, &md);
 274
 275                 /* Send the response. */
 276                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 277                 for (i = 0; i < 16; i++)
 278                         buffer_put_char(&msg, mdbuf[i]);
 279                 goto send;
 280         }
 281
 282 failure:
 283         /* Unknown identity or protocol error.  Send failure. */
 284         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 285 send:
 286         buffer_put_int(&e->output, buffer_len(&msg));
 287         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 288         key_free(key);
 289         BN_clear_free(challenge);
 290         buffer_free(&msg);
 291 }
 292
 293 /* ssh2 only */
 294 static void
 295 process_sign_request2(SocketEntry *e)
 296 {
 297         u_char *blob, *data, *signature = NULL;
 298         u_int blen, dlen, slen = 0;
 299         extern int datafellows;
 300         int ok = -1, flags;
 301         Buffer msg;
 302         Key *key;
 303
 304         datafellows = 0;
 305
 306         blob = buffer_get_string(&e->request, &blen);
 307         data = buffer_get_string(&e->request, &dlen);
 308
 309         flags = buffer_get_int(&e->request);
 310         if (flags & SSH_AGENT_OLD_SIGNATURE)
 311                 datafellows = SSH_BUG_SIGBLOB;
 312
 313         key = key_from_blob(blob, blen);
 314         if (key != NULL) {
 315                 Identity *id = lookup_identity(key, 2);
 316                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 317                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 318         }
 319         key_free(key);
 320         buffer_init(&msg);
 321         if (ok == 0) {
 322                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 323                 buffer_put_string(&msg, signature, slen);
 324         } else {
 325                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 326         }
 327         buffer_put_int(&e->output, buffer_len(&msg));
 328         buffer_append(&e->output, buffer_ptr(&msg),
 329             buffer_len(&msg));
 330         buffer_free(&msg);
 331         xfree(data);
 332         xfree(blob);
 333         if (signature != NULL)
 334                 xfree(signature);
 335 }
 336
 337 /* shared */
 338 static void
 339 process_remove_identity(SocketEntry *e, int version)
 340 {
 341         u_int blen, bits;
 342         int success = 0;
 343         Key *key = NULL;
 344         u_char *blob;
 345
 346         switch (version) {
 347         case 1:
 348                 key = key_new(KEY_RSA1);
 349                 bits = buffer_get_int(&e->request);
 350                 buffer_get_bignum(&e->request, key->rsa->e);
 351                 buffer_get_bignum(&e->request, key->rsa->n);
 352
 353                 if (bits != key_size(key))
 354                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 355                             key_size(key), bits);
 356                 break;
 357         case 2:
 358                 blob = buffer_get_string(&e->request, &blen);
 359                 key = key_from_blob(blob, blen);
 360                 xfree(blob);
 361                 break;
 362         }
 363         if (key != NULL) {
 364                 Identity *id = lookup_identity(key, version);
 365                 if (id != NULL) {
 366                         /*
 367                          * We have this key.  Free the old key.  Since we
 368                          * don't want to leave empty slots in the middle of
 369                          * the array, we actually free the key there and move
 370                          * all the entries between the empty slot and the end
 371                          * of the array.
 372                          */
 373                         Idtab *tab = idtab_lookup(version);
 374                         if (tab->nentries < 1)
 375                                 fatal("process_remove_identity: "
 376                                     "internal error: tab->nentries %d",
 377                                     tab->nentries);
 378                         TAILQ_REMOVE(&tab->idlist, id, next);
 379                         free_identity(id);
 380                         tab->nentries--;
 381                         success = 1;
 382                 }
 383                 key_free(key);
 384         }
 385         buffer_put_int(&e->output, 1);
 386         buffer_put_char(&e->output,
 387             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 388 }
 389
 390 static void
 391 process_remove_all_identities(SocketEntry *e, int version)
 392 {
 393         Idtab *tab = idtab_lookup(version);
 394         Identity *id;
 395
 396         /* Loop over all identities and clear the keys. */
 397         for (id = TAILQ_FIRST(&tab->idlist); id;
 398             id = TAILQ_FIRST(&tab->idlist)) {
 399                 TAILQ_REMOVE(&tab->idlist, id, next);
 400                 free_identity(id);
 401         }
 402
 403         /* Mark that there are no identities. */
 404         tab->nentries = 0;
 405
 406         /* Send success. */
 407         buffer_put_int(&e->output, 1);
 408         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 409 }
 410
 411 static void
 412 reaper(void)
 413 {
 414         u_int now = time(NULL);
 415         Identity *id, *nxt;
 416         int version;
 417         Idtab *tab;
 418
 419         for (version = 1; version < 3; version++) {
 420                 tab = idtab_lookup(version);
 421                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 422                         nxt = TAILQ_NEXT(id, next);
 423                         if (id->death != 0 && now >= id->death) {
 424                                 TAILQ_REMOVE(&tab->idlist, id, next);
 425                                 free_identity(id);
 426                                 tab->nentries--;
 427                         }
 428                 }
 429         }
 430 }
 431
 432 static void
 433 process_add_identity(SocketEntry *e, int version)
 434 {
 435         Idtab *tab = idtab_lookup(version);
 436         int type, success = 0, death = 0, confirm = 0;
 437         char *type_name, *comment;
 438         Key *k = NULL;
 439
 440         switch (version) {
 441         case 1:
 442                 k = key_new_private(KEY_RSA1);
 443                 (void) buffer_get_int(&e->request);             /* ignored */
 444                 buffer_get_bignum(&e->request, k->rsa->n);
 445                 buffer_get_bignum(&e->request, k->rsa->e);
 446                 buffer_get_bignum(&e->request, k->rsa->d);
 447                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 448
 449                 /* SSH and SSL have p and q swapped */
 450                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 451                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 452
 453                 /* Generate additional parameters */
 454                 rsa_generate_additional_parameters(k->rsa);
 455                 break;
 456         case 2:
 457                 type_name = buffer_get_string(&e->request, NULL);
 458                 type = key_type_from_name(type_name);
 459                 xfree(type_name);
 460                 switch (type) {
 461                 case KEY_DSA:
 462                         k = key_new_private(type);
 463                         buffer_get_bignum2(&e->request, k->dsa->p);
 464                         buffer_get_bignum2(&e->request, k->dsa->q);
 465                         buffer_get_bignum2(&e->request, k->dsa->g);
 466                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 467                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 468                         break;
 469                 case KEY_RSA:
 470                         k = key_new_private(type);
 471                         buffer_get_bignum2(&e->request, k->rsa->n);
 472                         buffer_get_bignum2(&e->request, k->rsa->e);
 473                         buffer_get_bignum2(&e->request, k->rsa->d);
 474                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 475                         buffer_get_bignum2(&e->request, k->rsa->p);
 476                         buffer_get_bignum2(&e->request, k->rsa->q);
 477
 478                         /* Generate additional parameters */
 479                         rsa_generate_additional_parameters(k->rsa);
 480                         break;
 481                 default:
 482                         buffer_clear(&e->request);
 483                         goto send;
 484                 }
 485                 break;
 486         }
 487         /* enable blinding */
 488         switch (k->type) {
 489         case KEY_RSA:
 490         case KEY_RSA1:
 491                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 492                         error("process_add_identity: RSA_blinding_on failed");
 493                         key_free(k);
 494                         goto send;
 495                 }
 496                 break;
 497         }
 498         comment = buffer_get_string(&e->request, NULL);
 499         if (k == NULL) {
 500                 xfree(comment);
 501                 goto send;
 502         }
 503         success = 1;
 504         while (buffer_len(&e->request)) {
 505                 switch (buffer_get_char(&e->request)) {
 506                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 507                         death = time(NULL) + buffer_get_int(&e->request);
 508                         break;
 509                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 510                         confirm = 1;
 511                         break;
 512                 default:
 513                         break;
 514                 }
 515         }
 516         if (lifetime && !death)
 517                 death = time(NULL) + lifetime;
 518         if (lookup_identity(k, version) == NULL) {
 519                 Identity *id = xmalloc(sizeof(Identity));
 520                 id->key = k;
 521                 id->comment = comment;
 522                 id->death = death;
 523                 id->confirm = confirm;
 524                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 525                 /* Increment the number of identities. */
 526                 tab->nentries++;
 527         } else {
 528                 key_free(k);
 529                 xfree(comment);
 530         }
 531 send:
 532         buffer_put_int(&e->output, 1);
 533         buffer_put_char(&e->output,
 534             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 535 }
 536
 537 /* XXX todo: encrypt sensitive data with passphrase */
 538 static void
 539 process_lock_agent(SocketEntry *e, int lock)
 540 {
 541         int success = 0;
 542         char *passwd;
 543
 544         passwd = buffer_get_string(&e->request, NULL);
 545         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 546                 locked = 0;
 547                 memset(lock_passwd, 0, strlen(lock_passwd));
 548                 xfree(lock_passwd);
 549                 lock_passwd = NULL;
 550                 success = 1;
 551         } else if (!locked && lock) {
 552                 locked = 1;
 553                 lock_passwd = xstrdup(passwd);
 554                 success = 1;
 555         }
 556         memset(passwd, 0, strlen(passwd));
 557         xfree(passwd);
 558
 559         buffer_put_int(&e->output, 1);
 560         buffer_put_char(&e->output,
 561             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 562 }
 563
 564 static void
 565 no_identities(SocketEntry *e, u_int type)
 566 {
 567         Buffer msg;
 568
 569         buffer_init(&msg);
 570         buffer_put_char(&msg,
 571             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 572             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 573         buffer_put_int(&msg, 0);
 574         buffer_put_int(&e->output, buffer_len(&msg));
 575         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 576         buffer_free(&msg);
 577 }
 578
 579 #ifdef SMARTCARD
 580 static void
 581 process_add_smartcard_key (SocketEntry *e)
 582 {
 583         char *sc_reader_id = NULL, *pin;
 584         int i, version, success = 0, death = 0, confirm = 0;
 585         Key **keys, *k;
 586         Identity *id;
 587         Idtab *tab;
 588
 589         sc_reader_id = buffer_get_string(&e->request, NULL);
 590         pin = buffer_get_string(&e->request, NULL);
 591
 592         while (buffer_len(&e->request)) {
 593                 switch (buffer_get_char(&e->request)) {
 594                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 595                         death = time(NULL) + buffer_get_int(&e->request);
 596                         break;
 597                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 598                         confirm = 1;
 599                         break;
 600                 default:
 601                         break;
 602                 }
 603         }
 604         if (lifetime && !death)
 605                 death = time(NULL) + lifetime;
 606
 607         keys = sc_get_keys(sc_reader_id, pin);
 608         xfree(sc_reader_id);
 609         xfree(pin);
 610
 611         if (keys == NULL || keys[0] == NULL) {
 612                 error("sc_get_keys failed");
 613                 goto send;
 614         }
 615         for (i = 0; keys[i] != NULL; i++) {
 616                 k = keys[i];
 617                 version = k->type == KEY_RSA1 ? 1 : 2;
 618                 tab = idtab_lookup(version);
 619                 if (lookup_identity(k, version) == NULL) {
 620                         id = xmalloc(sizeof(Identity));
 621                         id->key = k;
 622                         id->comment = sc_get_key_label(k);
 623                         id->death = death;
 624                         id->confirm = confirm;
 625                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 626                         tab->nentries++;
 627                         success = 1;
 628                 } else {
 629                         key_free(k);
 630                 }
 631                 keys[i] = NULL;
 632         }
 633         xfree(keys);
 634 send:
 635         buffer_put_int(&e->output, 1);
 636         buffer_put_char(&e->output,
 637             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 638 }
 639
 640 static void
 641 process_remove_smartcard_key(SocketEntry *e)
 642 {
 643         char *sc_reader_id = NULL, *pin;
 644         int i, version, success = 0;
 645         Key **keys, *k = NULL;
 646         Identity *id;
 647         Idtab *tab;
 648
 649         sc_reader_id = buffer_get_string(&e->request, NULL);
 650         pin = buffer_get_string(&e->request, NULL);
 651         keys = sc_get_keys(sc_reader_id, pin);
 652         xfree(sc_reader_id);
 653         xfree(pin);
 654
 655         if (keys == NULL || keys[0] == NULL) {
 656                 error("sc_get_keys failed");
 657                 goto send;
 658         }
 659         for (i = 0; keys[i] != NULL; i++) {
 660                 k = keys[i];
 661                 version = k->type == KEY_RSA1 ? 1 : 2;
 662                 if ((id = lookup_identity(k, version)) != NULL) {
 663                         tab = idtab_lookup(version);
 664                         TAILQ_REMOVE(&tab->idlist, id, next);
 665                         tab->nentries--;
 666                         free_identity(id);
 667                         success = 1;
 668                 }
 669                 key_free(k);
 670                 keys[i] = NULL;
 671         }
 672         xfree(keys);
 673 send:
 674         buffer_put_int(&e->output, 1);
 675         buffer_put_char(&e->output,
 676             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 677 }
 678 #endif /* SMARTCARD */
 679
 680 /* dispatch incoming messages */
 681
 682 static void
 683 process_message(SocketEntry *e)
 684 {
 685         u_int msg_len, type;
 686         u_char *cp;
 687
 688         /* kill dead keys */
 689         reaper();
 690
 691         if (buffer_len(&e->input) < 5)
 692                 return;         /* Incomplete message. */
 693         cp = buffer_ptr(&e->input);
 694         msg_len = get_u32(cp);
 695         if (msg_len > 256 * 1024) {
 696                 close_socket(e);
 697                 return;
 698         }
 699         if (buffer_len(&e->input) < msg_len + 4)
 700                 return;
 701
 702         /* move the current input to e->request */
 703         buffer_consume(&e->input, 4);
 704         buffer_clear(&e->request);
 705         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 706         buffer_consume(&e->input, msg_len);
 707         type = buffer_get_char(&e->request);
 708
 709         /* check wheter agent is locked */
 710         if (locked && type != SSH_AGENTC_UNLOCK) {
 711                 buffer_clear(&e->request);
 712                 switch (type) {
 713                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 714                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 715                         /* send empty lists */
 716                         no_identities(e, type);
 717                         break;
 718                 default:
 719                         /* send a fail message for all other request types */
 720                         buffer_put_int(&e->output, 1);
 721                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 722                 }
 723                 return;
 724         }
 725
 726         debug("type %d", type);
 727         switch (type) {
 728         case SSH_AGENTC_LOCK:
 729         case SSH_AGENTC_UNLOCK:
 730                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 731                 break;
 732         /* ssh1 */
 733         case SSH_AGENTC_RSA_CHALLENGE:
 734                 process_authentication_challenge1(e);
 735                 break;
 736         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 737                 process_request_identities(e, 1);
 738                 break;
 739         case SSH_AGENTC_ADD_RSA_IDENTITY:
 740         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 741                 process_add_identity(e, 1);
 742                 break;
 743         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 744                 process_remove_identity(e, 1);
 745                 break;
 746         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 747                 process_remove_all_identities(e, 1);
 748                 break;
 749         /* ssh2 */
 750         case SSH2_AGENTC_SIGN_REQUEST:
 751                 process_sign_request2(e);
 752                 break;
 753         case SSH2_AGENTC_REQUEST_IDENTITIES:
 754                 process_request_identities(e, 2);
 755                 break;
 756         case SSH2_AGENTC_ADD_IDENTITY:
 757         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 758                 process_add_identity(e, 2);
 759                 break;
 760         case SSH2_AGENTC_REMOVE_IDENTITY:
 761                 process_remove_identity(e, 2);
 762                 break;
 763         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 764                 process_remove_all_identities(e, 2);
 765                 break;
 766 #ifdef SMARTCARD
 767         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 768         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 769                 process_add_smartcard_key(e);
 770                 break;
 771         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 772                 process_remove_smartcard_key(e);
 773                 break;
 774 #endif /* SMARTCARD */
 775         default:
 776                 /* Unknown message.  Respond with failure. */
 777                 error("Unknown message %d", type);
 778                 buffer_clear(&e->request);
 779                 buffer_put_int(&e->output, 1);
 780                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 781                 break;
 782         }
 783 }
 784
 785 static void
 786 new_socket(sock_type type, int fd)
 787 {
 788         u_int i, old_alloc, new_alloc;
 789
 790         set_nonblock(fd);
 791
 792         if (fd > max_fd)
 793                 max_fd = fd;
 794
 795         for (i = 0; i < sockets_alloc; i++)
 796                 if (sockets[i].type == AUTH_UNUSED) {
 797                         sockets[i].fd = fd;
 798                         buffer_init(&sockets[i].input);
 799                         buffer_init(&sockets[i].output);
 800                         buffer_init(&sockets[i].request);
 801                         sockets[i].type = type;
 802                         return;
 803                 }
 804         old_alloc = sockets_alloc;
 805         new_alloc = sockets_alloc + 10;
 806         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 807         for (i = old_alloc; i < new_alloc; i++)
 808                 sockets[i].type = AUTH_UNUSED;
 809         sockets_alloc = new_alloc;
 810         sockets[old_alloc].fd = fd;
 811         buffer_init(&sockets[old_alloc].input);
 812         buffer_init(&sockets[old_alloc].output);
 813         buffer_init(&sockets[old_alloc].request);
 814         sockets[old_alloc].type = type;
 815 }
 816
 817 static int
 818 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
 819 {
 820         u_int i, sz;
 821         int n = 0;
 822
 823         for (i = 0; i < sockets_alloc; i++) {
 824                 switch (sockets[i].type) {
 825                 case AUTH_SOCKET:
 826                 case AUTH_CONNECTION:
 827                         n = MAX(n, sockets[i].fd);
 828                         break;
 829                 case AUTH_UNUSED:
 830                         break;
 831                 default:
 832                         fatal("Unknown socket type %d", sockets[i].type);
 833                         break;
 834                 }
 835         }
 836
 837         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 838         if (*fdrp == NULL || sz > *nallocp) {
 839                 if (*fdrp)
 840                         xfree(*fdrp);
 841                 if (*fdwp)
 842                         xfree(*fdwp);
 843                 *fdrp = xmalloc(sz);
 844                 *fdwp = xmalloc(sz);
 845                 *nallocp = sz;
 846         }
 847         if (n < *fdl)
 848                 debug("XXX shrink: %d < %d", n, *fdl);
 849         *fdl = n;
 850         memset(*fdrp, 0, sz);
 851         memset(*fdwp, 0, sz);
 852
 853         for (i = 0; i < sockets_alloc; i++) {
 854                 switch (sockets[i].type) {
 855                 case AUTH_SOCKET:
 856                 case AUTH_CONNECTION:
 857                         FD_SET(sockets[i].fd, *fdrp);
 858                         if (buffer_len(&sockets[i].output) > 0)
 859                                 FD_SET(sockets[i].fd, *fdwp);
 860                         break;
 861                 default:
 862                         break;
 863                 }
 864         }
 865         return (1);
 866 }
 867
 868 static void
 869 after_select(fd_set *readset, fd_set *writeset)
 870 {
 871         struct sockaddr_un sunaddr;
 872         socklen_t slen;
 873         char buf[1024];
 874         int len, sock;
 875         u_int i;
 876         uid_t euid;
 877         gid_t egid;
 878
 879         for (i = 0; i < sockets_alloc; i++)
 880                 switch (sockets[i].type) {
 881                 case AUTH_UNUSED:
 882                         break;
 883                 case AUTH_SOCKET:
 884                         if (FD_ISSET(sockets[i].fd, readset)) {
 885                                 slen = sizeof(sunaddr);
 886                                 sock = accept(sockets[i].fd,
 887                                     (struct sockaddr *)&sunaddr, &slen);
 888                                 if (sock < 0) {
 889                                         error("accept from AUTH_SOCKET: %s",
 890                                             strerror(errno));
 891                                         break;
 892                                 }
 893                                 if (getpeereid(sock, &euid, &egid) < 0) {
 894                                         error("getpeereid %d failed: %s",
 895                                             sock, strerror(errno));
 896                                         close(sock);
 897                                         break;
 898                                 }
 899                                 if ((euid != 0) && (getuid() != euid)) {
 900                                         error("uid mismatch: "
 901                                             "peer euid %u != uid %u",
 902                                             (u_int) euid, (u_int) getuid());
 903                                         close(sock);
 904                                         break;
 905                                 }
 906                                 new_socket(AUTH_CONNECTION, sock);
 907                         }
 908                         break;
 909                 case AUTH_CONNECTION:
 910                         if (buffer_len(&sockets[i].output) > 0 &&
 911                             FD_ISSET(sockets[i].fd, writeset)) {
 912                                 do {
 913                                         len = write(sockets[i].fd,
 914                                             buffer_ptr(&sockets[i].output),
 915                                             buffer_len(&sockets[i].output));
 916                                         if (len == -1 && (errno == EAGAIN ||
 917                                             errno == EINTR))
 918                                                 continue;
 919                                         break;
 920                                 } while (1);
 921                                 if (len <= 0) {
 922                                         close_socket(&sockets[i]);
 923                                         break;
 924                                 }
 925                                 buffer_consume(&sockets[i].output, len);
 926                         }
 927                         if (FD_ISSET(sockets[i].fd, readset)) {
 928                                 do {
 929                                         len = read(sockets[i].fd, buf, sizeof(buf));
 930                                         if (len == -1 && (errno == EAGAIN ||
 931                                             errno == EINTR))
 932                                                 continue;
 933                                         break;
 934                                 } while (1);
 935                                 if (len <= 0) {
 936                                         close_socket(&sockets[i]);
 937                                         break;
 938                                 }
 939                                 buffer_append(&sockets[i].input, buf, len);
 940                                 process_message(&sockets[i]);
 941                         }
 942                         break;
 943                 default:
 944                         fatal("Unknown type %d", sockets[i].type);
 945                 }
 946 }
 947
 948 static void
 949 cleanup_socket(void)
 950 {
 951         if (socket_name[0])
 952                 unlink(socket_name);
 953         if (socket_dir[0])
 954                 rmdir(socket_dir);
 955 }
 956
 957 void
 958 cleanup_exit(int i)
 959 {
 960         cleanup_socket();
 961         _exit(i);
 962 }
 963
 964 /*ARGSUSED*/
 965 static void
 966 cleanup_handler(int sig)
 967 {
 968         cleanup_socket();
 969         _exit(2);
 970 }
 971
 972 /*ARGSUSED*/
 973 static void
 974 check_parent_exists(int sig)
 975 {
 976         int save_errno = errno;
 977
 978         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 979                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 980                 cleanup_handler(sig); /* safe */
 981         }
 982         mysignal(SIGALRM, check_parent_exists);
 983         alarm(10);
 984         errno = save_errno;
 985 }
 986
 987 static void
 988 usage(void)
 989 {
 990         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 991             __progname);
 992         fprintf(stderr, "Options:\n");
 993         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 994         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 995         fprintf(stderr, "  -k          Kill the current agent.\n");
 996         fprintf(stderr, "  -d          Debug mode.\n");
 997         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 998         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
 999         exit(1);
1000 }
1001
1002 int
1003 main(int ac, char **av)
1004 {
1005         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1006         int sock, fd,  ch;
1007         u_int nalloc;
1008         char *shell, *format, *pidstr, *agentsocket = NULL;
1009         fd_set *readsetp = NULL, *writesetp = NULL;
1010         struct sockaddr_un sunaddr;
1011 #ifdef HAVE_SETRLIMIT
1012         struct rlimit rlim;
1013 #endif
1014         int prev_mask;
1015         extern int optind;
1016         extern char *optarg;
1017         pid_t pid;
1018         char pidstrbuf[1 + 3 * sizeof pid];
1019
1020         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1021         sanitise_stdfd();
1022
1023         /* drop */
1024         setegid(getgid());
1025         setgid(getgid());
1026
1027 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1028         /* Disable ptrace on Linux without sgid bit */
1029         prctl(PR_SET_DUMPABLE, 0);
1030 #endif
1031
1032         SSLeay_add_all_algorithms();
1033
1034         __progname = ssh_get_progname(av[0]);
1035         init_rng();
1036         seed_rng();
1037
1038         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1039                 switch (ch) {
1040                 case 'c':
1041                         if (s_flag)
1042                                 usage();
1043                         c_flag++;
1044                         break;
1045                 case 'k':
1046                         k_flag++;
1047                         break;
1048                 case 's':
1049                         if (c_flag)
1050                                 usage();
1051                         s_flag++;
1052                         break;
1053                 case 'd':
1054                         if (d_flag)
1055                                 usage();
1056                         d_flag++;
1057                         break;
1058                 case 'a':
1059                         agentsocket = optarg;
1060                         break;
1061                 case 't':
1062                         if ((lifetime = convtime(optarg)) == -1) {
1063                                 fprintf(stderr, "Invalid lifetime\n");
1064                                 usage();
1065                         }
1066                         break;
1067                 default:
1068                         usage();
1069                 }
1070         }
1071         ac -= optind;
1072         av += optind;
1073
1074         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1075                 usage();
1076
1077         if (ac == 0 && !c_flag && !s_flag) {
1078                 shell = getenv("SHELL");
1079                 if (shell != NULL &&
1080                     strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1081                         c_flag = 1;
1082         }
1083         if (k_flag) {
1084                 const char *errstr = NULL;
1085
1086                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1087                 if (pidstr == NULL) {
1088                         fprintf(stderr, "%s not set, cannot kill agent\n",
1089                             SSH_AGENTPID_ENV_NAME);
1090                         exit(1);
1091                 }
1092                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1093                 if (errstr) {
1094                         fprintf(stderr,
1095                             "%s=\"%s\", which is not a good PID: %s\n",
1096                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1097                         exit(1);
1098                 }
1099                 if (kill(pid, SIGTERM) == -1) {
1100                         perror("kill");
1101                         exit(1);
1102                 }
1103                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1104                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1105                 printf(format, SSH_AGENTPID_ENV_NAME);
1106                 printf("echo Agent pid %ld killed;\n", (long)pid);
1107                 exit(0);
1108         }
1109         parent_pid = getpid();
1110
1111         if (agentsocket == NULL) {
1112                 /* Create private directory for agent socket */
1113                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1114                 if (mkdtemp(socket_dir) == NULL) {
1115                         perror("mkdtemp: private socket dir");
1116                         exit(1);
1117                 }
1118                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1119                     (long)parent_pid);
1120         } else {
1121                 /* Try to use specified agent socket */
1122                 socket_dir[0] = '\0';
1123                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1124         }
1125
1126         /*
1127          * Create socket early so it will exist before command gets run from
1128          * the parent.
1129          */
1130         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1131         if (sock < 0) {
1132                 perror("socket");
1133                 *socket_name = '\0'; /* Don't unlink any existing file */
1134                 cleanup_exit(1);
1135         }
1136         memset(&sunaddr, 0, sizeof(sunaddr));
1137         sunaddr.sun_family = AF_UNIX;
1138         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1139         prev_mask = umask(0177);
1140         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1141                 perror("bind");
1142                 *socket_name = '\0'; /* Don't unlink any existing file */
1143                 umask(prev_mask);
1144                 cleanup_exit(1);
1145         }
1146         umask(prev_mask);
1147         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1148                 perror("listen");
1149                 cleanup_exit(1);
1150         }
1151
1152         /*
1153          * Fork, and have the parent execute the command, if any, or present
1154          * the socket data.  The child continues as the authentication agent.
1155          */
1156         if (d_flag) {
1157                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1158                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1159                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1160                     SSH_AUTHSOCKET_ENV_NAME);
1161                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1162                 goto skip;
1163         }
1164         pid = fork();
1165         if (pid == -1) {
1166                 perror("fork");
1167                 cleanup_exit(1);
1168         }
1169         if (pid != 0) {         /* Parent - execute the given command. */
1170                 close(sock);
1171                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1172                 if (ac == 0) {
1173                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1174                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1175                             SSH_AUTHSOCKET_ENV_NAME);
1176                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1177                             SSH_AGENTPID_ENV_NAME);
1178                         printf("echo Agent pid %ld;\n", (long)pid);
1179                         exit(0);
1180                 }
1181                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1182                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1183                         perror("setenv");
1184                         exit(1);
1185                 }
1186                 execvp(av[0], av);
1187                 perror(av[0]);
1188                 exit(1);
1189         }
1190         /* child */
1191         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1192
1193         if (setsid() == -1) {
1194                 error("setsid: %s", strerror(errno));
1195                 cleanup_exit(1);
1196         }
1197
1198         (void)chdir("/");
1199         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1200                 /* XXX might close listen socket */
1201                 (void)dup2(fd, STDIN_FILENO);
1202                 (void)dup2(fd, STDOUT_FILENO);
1203                 (void)dup2(fd, STDERR_FILENO);
1204                 if (fd > 2)
1205                         close(fd);
1206         }
1207
1208 #ifdef HAVE_SETRLIMIT
1209         /* deny core dumps, since memory contains unencrypted private keys */
1210         rlim.rlim_cur = rlim.rlim_max = 0;
1211         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1212                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1213                 cleanup_exit(1);
1214         }
1215 #endif
1216
1217 skip:
1218         new_socket(AUTH_SOCKET, sock);
1219         if (ac > 0) {
1220                 mysignal(SIGALRM, check_parent_exists);
1221                 alarm(10);
1222         }
1223         idtab_init();
1224         if (!d_flag)
1225                 signal(SIGINT, SIG_IGN);
1226         signal(SIGPIPE, SIG_IGN);
1227         signal(SIGHUP, cleanup_handler);
1228         signal(SIGTERM, cleanup_handler);
1229         nalloc = 0;
1230
1231         while (1) {
1232                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1233                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1234                         if (errno == EINTR)
1235                                 continue;
1236                         fatal("select: %s", strerror(errno));
1237                 }
1238                 after_select(readsetp, writesetp);
1239         }
1240         /* NOTREACHED */
1241 }