ssh-agent.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * The authentication agent program.
   6  *
   7  * As far as I am concerned, the code I have written for this software
   8  * can be used freely for any purpose.  Any derived versions of this
   9  * software must be clearly marked as such, and if the derived work is
  10  * incompatible with the protocol description in the RFC file, it must be
  11  * called by a name other than "ssh" or "Secure Shell".
  12  *
  13  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  14  *
  15  * Redistribution and use in source and binary forms, with or without
  16  * modification, are permitted provided that the following conditions
  17  * are met:
  18  * 1. Redistributions of source code must retain the above copyright
  19  *    notice, this list of conditions and the following disclaimer.
  20  * 2. Redistributions in binary form must reproduce the above copyright
  21  *    notice, this list of conditions and the following disclaimer in the
  22  *    documentation and/or other materials provided with the distribution.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  27  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  28  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  29  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  30  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  31  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  32  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  33  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 #include "includes.h"
  37 RCSID("$OpenBSD: ssh-agent.c,v 1.129 2006/02/20 17:02:44 stevesk Exp $");
  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 "getput.h"
  60 #include "key.h"
  61 #include "authfd.h"
  62 #include "compat.h"
  63 #include "log.h"
  64 #include "misc.h"
  65
  66 #ifdef SMARTCARD
  67 #include "scard.h"
  68 #endif
  69
  70 #if defined(HAVE_SYS_PRCTL_H)
  71 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  72 #endif
  73
  74 typedef enum {
  75         AUTH_UNUSED,
  76         AUTH_SOCKET,
  77         AUTH_CONNECTION
  78 } sock_type;
  79
  80 typedef struct {
  81         int fd;
  82         sock_type type;
  83         Buffer input;
  84         Buffer output;
  85         Buffer request;
  86 } SocketEntry;
  87
  88 u_int sockets_alloc = 0;
  89 SocketEntry *sockets = NULL;
  90
  91 typedef struct identity {
  92         TAILQ_ENTRY(identity) next;
  93         Key *key;
  94         char *comment;
  95         u_int death;
  96         u_int confirm;
  97 } Identity;
  98
  99 typedef struct {
 100         int nentries;
 101         TAILQ_HEAD(idqueue, identity) idlist;
 102 } Idtab;
 103
 104 /* private key table, one per protocol version */
 105 Idtab idtable[3];
 106
 107 int max_fd = 0;
 108
 109 /* pid of shell == parent of agent */
 110 pid_t parent_pid = -1;
 111
 112 /* pathname and directory for AUTH_SOCKET */
 113 char socket_name[1024];
 114 char socket_dir[1024];
 115
 116 /* locking */
 117 int locked = 0;
 118 char *lock_passwd = NULL;
 119
 120 extern char *__progname;
 121
 122 /* Default lifetime (0 == forever) */
 123 static int lifetime = 0;
 124
 125 static void
 126 close_socket(SocketEntry *e)
 127 {
 128         close(e->fd);
 129         e->fd = -1;
 130         e->type = AUTH_UNUSED;
 131         buffer_free(&e->input);
 132         buffer_free(&e->output);
 133         buffer_free(&e->request);
 134 }
 135
 136 static void
 137 idtab_init(void)
 138 {
 139         int i;
 140
 141         for (i = 0; i <=2; i++) {
 142                 TAILQ_INIT(&idtable[i].idlist);
 143                 idtable[i].nentries = 0;
 144         }
 145 }
 146
 147 /* return private key table for requested protocol version */
 148 static Idtab *
 149 idtab_lookup(int version)
 150 {
 151         if (version < 1 || version > 2)
 152                 fatal("internal error, bad protocol version %d", version);
 153         return &idtable[version];
 154 }
 155
 156 static void
 157 free_identity(Identity *id)
 158 {
 159         key_free(id->key);
 160         xfree(id->comment);
 161         xfree(id);
 162 }
 163
 164 /* return matching private key for given public key */
 165 static Identity *
 166 lookup_identity(Key *key, int version)
 167 {
 168         Identity *id;
 169
 170         Idtab *tab = idtab_lookup(version);
 171         TAILQ_FOREACH(id, &tab->idlist, next) {
 172                 if (key_equal(key, id->key))
 173                         return (id);
 174         }
 175         return (NULL);
 176 }
 177
 178 /* Check confirmation of keysign request */
 179 static int
 180 confirm_key(Identity *id)
 181 {
 182         char *p;
 183         int ret = -1;
 184
 185         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 186         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 187             id->comment, p))
 188                 ret = 0;
 189         xfree(p);
 190
 191         return (ret);
 192 }
 193
 194 /* send list of supported public keys to 'client' */
 195 static void
 196 process_request_identities(SocketEntry *e, int version)
 197 {
 198         Idtab *tab = idtab_lookup(version);
 199         Identity *id;
 200         Buffer msg;
 201
 202         buffer_init(&msg);
 203         buffer_put_char(&msg, (version == 1) ?
 204             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 205         buffer_put_int(&msg, tab->nentries);
 206         TAILQ_FOREACH(id, &tab->idlist, next) {
 207                 if (id->key->type == KEY_RSA1) {
 208                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 209                         buffer_put_bignum(&msg, id->key->rsa->e);
 210                         buffer_put_bignum(&msg, id->key->rsa->n);
 211                 } else {
 212                         u_char *blob;
 213                         u_int blen;
 214                         key_to_blob(id->key, &blob, &blen);
 215                         buffer_put_string(&msg, blob, blen);
 216                         xfree(blob);
 217                 }
 218                 buffer_put_cstring(&msg, id->comment);
 219         }
 220         buffer_put_int(&e->output, buffer_len(&msg));
 221         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 222         buffer_free(&msg);
 223 }
 224
 225 /* ssh1 only */
 226 static void
 227 process_authentication_challenge1(SocketEntry *e)
 228 {
 229         u_char buf[32], mdbuf[16], session_id[16];
 230         u_int response_type;
 231         BIGNUM *challenge;
 232         Identity *id;
 233         int i, len;
 234         Buffer msg;
 235         MD5_CTX md;
 236         Key *key;
 237
 238         buffer_init(&msg);
 239         key = key_new(KEY_RSA1);
 240         if ((challenge = BN_new()) == NULL)
 241                 fatal("process_authentication_challenge1: BN_new failed");
 242
 243         (void) buffer_get_int(&e->request);                     /* ignored */
 244         buffer_get_bignum(&e->request, key->rsa->e);
 245         buffer_get_bignum(&e->request, key->rsa->n);
 246         buffer_get_bignum(&e->request, challenge);
 247
 248         /* Only protocol 1.1 is supported */
 249         if (buffer_len(&e->request) == 0)
 250                 goto failure;
 251         buffer_get(&e->request, session_id, 16);
 252         response_type = buffer_get_int(&e->request);
 253         if (response_type != 1)
 254                 goto failure;
 255
 256         id = lookup_identity(key, 1);
 257         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 258                 Key *private = id->key;
 259                 /* Decrypt the challenge using the private key. */
 260                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 261                         goto failure;
 262
 263                 /* The response is MD5 of decrypted challenge plus session id. */
 264                 len = BN_num_bytes(challenge);
 265                 if (len <= 0 || len > 32) {
 266                         logit("process_authentication_challenge: bad challenge length %d", len);
 267                         goto failure;
 268                 }
 269                 memset(buf, 0, 32);
 270                 BN_bn2bin(challenge, buf + 32 - len);
 271                 MD5_Init(&md);
 272                 MD5_Update(&md, buf, 32);
 273                 MD5_Update(&md, session_id, 16);
 274                 MD5_Final(mdbuf, &md);
 275
 276                 /* Send the response. */
 277                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 278                 for (i = 0; i < 16; i++)
 279                         buffer_put_char(&msg, mdbuf[i]);
 280                 goto send;
 281         }
 282
 283 failure:
 284         /* Unknown identity or protocol error.  Send failure. */
 285         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 286 send:
 287         buffer_put_int(&e->output, buffer_len(&msg));
 288         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 289         key_free(key);
 290         BN_clear_free(challenge);
 291         buffer_free(&msg);
 292 }
 293
 294 /* ssh2 only */
 295 static void
 296 process_sign_request2(SocketEntry *e)
 297 {
 298         u_char *blob, *data, *signature = NULL;
 299         u_int blen, dlen, slen = 0;
 300         extern int datafellows;
 301         int ok = -1, flags;
 302         Buffer msg;
 303         Key *key;
 304
 305         datafellows = 0;
 306
 307         blob = buffer_get_string(&e->request, &blen);
 308         data = buffer_get_string(&e->request, &dlen);
 309
 310         flags = buffer_get_int(&e->request);
 311         if (flags & SSH_AGENT_OLD_SIGNATURE)
 312                 datafellows = SSH_BUG_SIGBLOB;
 313
 314         key = key_from_blob(blob, blen);
 315         if (key != NULL) {
 316                 Identity *id = lookup_identity(key, 2);
 317                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 318                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 319         }
 320         key_free(key);
 321         buffer_init(&msg);
 322         if (ok == 0) {
 323                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 324                 buffer_put_string(&msg, signature, slen);
 325         } else {
 326                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 327         }
 328         buffer_put_int(&e->output, buffer_len(&msg));
 329         buffer_append(&e->output, buffer_ptr(&msg),
 330             buffer_len(&msg));
 331         buffer_free(&msg);
 332         xfree(data);
 333         xfree(blob);
 334         if (signature != NULL)
 335                 xfree(signature);
 336 }
 337
 338 /* shared */
 339 static void
 340 process_remove_identity(SocketEntry *e, int version)
 341 {
 342         u_int blen, bits;
 343         int success = 0;
 344         Key *key = NULL;
 345         u_char *blob;
 346
 347         switch (version) {
 348         case 1:
 349                 key = key_new(KEY_RSA1);
 350                 bits = buffer_get_int(&e->request);
 351                 buffer_get_bignum(&e->request, key->rsa->e);
 352                 buffer_get_bignum(&e->request, key->rsa->n);
 353
 354                 if (bits != key_size(key))
 355                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 356                             key_size(key), bits);
 357                 break;
 358         case 2:
 359                 blob = buffer_get_string(&e->request, &blen);
 360                 key = key_from_blob(blob, blen);
 361                 xfree(blob);
 362                 break;
 363         }
 364         if (key != NULL) {
 365                 Identity *id = lookup_identity(key, version);
 366                 if (id != NULL) {
 367                         /*
 368                          * We have this key.  Free the old key.  Since we
 369                          * don't want to leave empty slots in the middle of
 370                          * the array, we actually free the key there and move
 371                          * all the entries between the empty slot and the end
 372                          * of the array.
 373                          */
 374                         Idtab *tab = idtab_lookup(version);
 375                         if (tab->nentries < 1)
 376                                 fatal("process_remove_identity: "
 377                                     "internal error: tab->nentries %d",
 378                                     tab->nentries);
 379                         TAILQ_REMOVE(&tab->idlist, id, next);
 380                         free_identity(id);
 381                         tab->nentries--;
 382                         success = 1;
 383                 }
 384                 key_free(key);
 385         }
 386         buffer_put_int(&e->output, 1);
 387         buffer_put_char(&e->output,
 388             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 389 }
 390
 391 static void
 392 process_remove_all_identities(SocketEntry *e, int version)
 393 {
 394         Idtab *tab = idtab_lookup(version);
 395         Identity *id;
 396
 397         /* Loop over all identities and clear the keys. */
 398         for (id = TAILQ_FIRST(&tab->idlist); id;
 399             id = TAILQ_FIRST(&tab->idlist)) {
 400                 TAILQ_REMOVE(&tab->idlist, id, next);
 401                 free_identity(id);
 402         }
 403
 404         /* Mark that there are no identities. */
 405         tab->nentries = 0;
 406
 407         /* Send success. */
 408         buffer_put_int(&e->output, 1);
 409         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 410 }
 411
 412 static void
 413 reaper(void)
 414 {
 415         u_int now = time(NULL);
 416         Identity *id, *nxt;
 417         int version;
 418         Idtab *tab;
 419
 420         for (version = 1; version < 3; version++) {
 421                 tab = idtab_lookup(version);
 422                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 423                         nxt = TAILQ_NEXT(id, next);
 424                         if (id->death != 0 && now >= id->death) {
 425                                 TAILQ_REMOVE(&tab->idlist, id, next);
 426                                 free_identity(id);
 427                                 tab->nentries--;
 428                         }
 429                 }
 430         }
 431 }
 432
 433 static void
 434 process_add_identity(SocketEntry *e, int version)
 435 {
 436         Idtab *tab = idtab_lookup(version);
 437         int type, success = 0, death = 0, confirm = 0;
 438         char *type_name, *comment;
 439         Key *k = NULL;
 440
 441         switch (version) {
 442         case 1:
 443                 k = key_new_private(KEY_RSA1);
 444                 (void) buffer_get_int(&e->request);             /* ignored */
 445                 buffer_get_bignum(&e->request, k->rsa->n);
 446                 buffer_get_bignum(&e->request, k->rsa->e);
 447                 buffer_get_bignum(&e->request, k->rsa->d);
 448                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 449
 450                 /* SSH and SSL have p and q swapped */
 451                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 452                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 453
 454                 /* Generate additional parameters */
 455                 rsa_generate_additional_parameters(k->rsa);
 456                 break;
 457         case 2:
 458                 type_name = buffer_get_string(&e->request, NULL);
 459                 type = key_type_from_name(type_name);
 460                 xfree(type_name);
 461                 switch (type) {
 462                 case KEY_DSA:
 463                         k = key_new_private(type);
 464                         buffer_get_bignum2(&e->request, k->dsa->p);
 465                         buffer_get_bignum2(&e->request, k->dsa->q);
 466                         buffer_get_bignum2(&e->request, k->dsa->g);
 467                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 468                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 469                         break;
 470                 case KEY_RSA:
 471                         k = key_new_private(type);
 472                         buffer_get_bignum2(&e->request, k->rsa->n);
 473                         buffer_get_bignum2(&e->request, k->rsa->e);
 474                         buffer_get_bignum2(&e->request, k->rsa->d);
 475                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 476                         buffer_get_bignum2(&e->request, k->rsa->p);
 477                         buffer_get_bignum2(&e->request, k->rsa->q);
 478
 479                         /* Generate additional parameters */
 480                         rsa_generate_additional_parameters(k->rsa);
 481                         break;
 482                 default:
 483                         buffer_clear(&e->request);
 484                         goto send;
 485                 }
 486                 break;
 487         }
 488         /* enable blinding */
 489         switch (k->type) {
 490         case KEY_RSA:
 491         case KEY_RSA1:
 492                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 493                         error("process_add_identity: RSA_blinding_on failed");
 494                         key_free(k);
 495                         goto send;
 496                 }
 497                 break;
 498         }
 499         comment = buffer_get_string(&e->request, NULL);
 500         if (k == NULL) {
 501                 xfree(comment);
 502                 goto send;
 503         }
 504         success = 1;
 505         while (buffer_len(&e->request)) {
 506                 switch (buffer_get_char(&e->request)) {
 507                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 508                         death = time(NULL) + buffer_get_int(&e->request);
 509                         break;
 510                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 511                         confirm = 1;
 512                         break;
 513                 default:
 514                         break;
 515                 }
 516         }
 517         if (lifetime && !death)
 518                 death = time(NULL) + lifetime;
 519         if (lookup_identity(k, version) == NULL) {
 520                 Identity *id = xmalloc(sizeof(Identity));
 521                 id->key = k;
 522                 id->comment = comment;
 523                 id->death = death;
 524                 id->confirm = confirm;
 525                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 526                 /* Increment the number of identities. */
 527                 tab->nentries++;
 528         } else {
 529                 key_free(k);
 530                 xfree(comment);
 531         }
 532 send:
 533         buffer_put_int(&e->output, 1);
 534         buffer_put_char(&e->output,
 535             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 536 }
 537
 538 /* XXX todo: encrypt sensitive data with passphrase */
 539 static void
 540 process_lock_agent(SocketEntry *e, int lock)
 541 {
 542         int success = 0;
 543         char *passwd;
 544
 545         passwd = buffer_get_string(&e->request, NULL);
 546         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 547                 locked = 0;
 548                 memset(lock_passwd, 0, strlen(lock_passwd));
 549                 xfree(lock_passwd);
 550                 lock_passwd = NULL;
 551                 success = 1;
 552         } else if (!locked && lock) {
 553                 locked = 1;
 554                 lock_passwd = xstrdup(passwd);
 555                 success = 1;
 556         }
 557         memset(passwd, 0, strlen(passwd));
 558         xfree(passwd);
 559
 560         buffer_put_int(&e->output, 1);
 561         buffer_put_char(&e->output,
 562             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 563 }
 564
 565 static void
 566 no_identities(SocketEntry *e, u_int type)
 567 {
 568         Buffer msg;
 569
 570         buffer_init(&msg);
 571         buffer_put_char(&msg,
 572             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 573             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 574         buffer_put_int(&msg, 0);
 575         buffer_put_int(&e->output, buffer_len(&msg));
 576         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 577         buffer_free(&msg);
 578 }
 579
 580 #ifdef SMARTCARD
 581 static void
 582 process_add_smartcard_key (SocketEntry *e)
 583 {
 584         char *sc_reader_id = NULL, *pin;
 585         int i, version, success = 0, death = 0, confirm = 0;
 586         Key **keys, *k;
 587         Identity *id;
 588         Idtab *tab;
 589
 590         sc_reader_id = buffer_get_string(&e->request, NULL);
 591         pin = buffer_get_string(&e->request, NULL);
 592
 593         while (buffer_len(&e->request)) {
 594                 switch (buffer_get_char(&e->request)) {
 595                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 596                         death = time(NULL) + buffer_get_int(&e->request);
 597                         break;
 598                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 599                         confirm = 1;
 600                         break;
 601                 default:
 602                         break;
 603                 }
 604         }
 605         if (lifetime && !death)
 606                 death = time(NULL) + lifetime;
 607
 608         keys = sc_get_keys(sc_reader_id, pin);
 609         xfree(sc_reader_id);
 610         xfree(pin);
 611
 612         if (keys == NULL || keys[0] == NULL) {
 613                 error("sc_get_keys failed");
 614                 goto send;
 615         }
 616         for (i = 0; keys[i] != NULL; i++) {
 617                 k = keys[i];
 618                 version = k->type == KEY_RSA1 ? 1 : 2;
 619                 tab = idtab_lookup(version);
 620                 if (lookup_identity(k, version) == NULL) {
 621                         id = xmalloc(sizeof(Identity));
 622                         id->key = k;
 623                         id->comment = sc_get_key_label(k);
 624                         id->death = death;
 625                         id->confirm = confirm;
 626                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 627                         tab->nentries++;
 628                         success = 1;
 629                 } else {
 630                         key_free(k);
 631                 }
 632                 keys[i] = NULL;
 633         }
 634         xfree(keys);
 635 send:
 636         buffer_put_int(&e->output, 1);
 637         buffer_put_char(&e->output,
 638             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 639 }
 640
 641 static void
 642 process_remove_smartcard_key(SocketEntry *e)
 643 {
 644         char *sc_reader_id = NULL, *pin;
 645         int i, version, success = 0;
 646         Key **keys, *k = NULL;
 647         Identity *id;
 648         Idtab *tab;
 649
 650         sc_reader_id = buffer_get_string(&e->request, NULL);
 651         pin = buffer_get_string(&e->request, NULL);
 652         keys = sc_get_keys(sc_reader_id, pin);
 653         xfree(sc_reader_id);
 654         xfree(pin);
 655
 656         if (keys == NULL || keys[0] == NULL) {
 657                 error("sc_get_keys failed");
 658                 goto send;
 659         }
 660         for (i = 0; keys[i] != NULL; i++) {
 661                 k = keys[i];
 662                 version = k->type == KEY_RSA1 ? 1 : 2;
 663                 if ((id = lookup_identity(k, version)) != NULL) {
 664                         tab = idtab_lookup(version);
 665                         TAILQ_REMOVE(&tab->idlist, id, next);
 666                         tab->nentries--;
 667                         free_identity(id);
 668                         success = 1;
 669                 }
 670                 key_free(k);
 671                 keys[i] = NULL;
 672         }
 673         xfree(keys);
 674 send:
 675         buffer_put_int(&e->output, 1);
 676         buffer_put_char(&e->output,
 677             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 678 }
 679 #endif /* SMARTCARD */
 680
 681 /* dispatch incoming messages */
 682
 683 static void
 684 process_message(SocketEntry *e)
 685 {
 686         u_int msg_len, type;
 687         u_char *cp;
 688
 689         /* kill dead keys */
 690         reaper();
 691
 692         if (buffer_len(&e->input) < 5)
 693                 return;         /* Incomplete message. */
 694         cp = buffer_ptr(&e->input);
 695         msg_len = GET_32BIT(cp);
 696         if (msg_len > 256 * 1024) {
 697                 close_socket(e);
 698                 return;
 699         }
 700         if (buffer_len(&e->input) < msg_len + 4)
 701                 return;
 702
 703         /* move the current input to e->request */
 704         buffer_consume(&e->input, 4);
 705         buffer_clear(&e->request);
 706         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 707         buffer_consume(&e->input, msg_len);
 708         type = buffer_get_char(&e->request);
 709
 710         /* check wheter agent is locked */
 711         if (locked && type != SSH_AGENTC_UNLOCK) {
 712                 buffer_clear(&e->request);
 713                 switch (type) {
 714                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 715                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 716                         /* send empty lists */
 717                         no_identities(e, type);
 718                         break;
 719                 default:
 720                         /* send a fail message for all other request types */
 721                         buffer_put_int(&e->output, 1);
 722                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 723                 }
 724                 return;
 725         }
 726
 727         debug("type %d", type);
 728         switch (type) {
 729         case SSH_AGENTC_LOCK:
 730         case SSH_AGENTC_UNLOCK:
 731                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 732                 break;
 733         /* ssh1 */
 734         case SSH_AGENTC_RSA_CHALLENGE:
 735                 process_authentication_challenge1(e);
 736                 break;
 737         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 738                 process_request_identities(e, 1);
 739                 break;
 740         case SSH_AGENTC_ADD_RSA_IDENTITY:
 741         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 742                 process_add_identity(e, 1);
 743                 break;
 744         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 745                 process_remove_identity(e, 1);
 746                 break;
 747         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 748                 process_remove_all_identities(e, 1);
 749                 break;
 750         /* ssh2 */
 751         case SSH2_AGENTC_SIGN_REQUEST:
 752                 process_sign_request2(e);
 753                 break;
 754         case SSH2_AGENTC_REQUEST_IDENTITIES:
 755                 process_request_identities(e, 2);
 756                 break;
 757         case SSH2_AGENTC_ADD_IDENTITY:
 758         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 759                 process_add_identity(e, 2);
 760                 break;
 761         case SSH2_AGENTC_REMOVE_IDENTITY:
 762                 process_remove_identity(e, 2);
 763                 break;
 764         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 765                 process_remove_all_identities(e, 2);
 766                 break;
 767 #ifdef SMARTCARD
 768         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 769         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 770                 process_add_smartcard_key(e);
 771                 break;
 772         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 773                 process_remove_smartcard_key(e);
 774                 break;
 775 #endif /* SMARTCARD */
 776         default:
 777                 /* Unknown message.  Respond with failure. */
 778                 error("Unknown message %d", type);
 779                 buffer_clear(&e->request);
 780                 buffer_put_int(&e->output, 1);
 781                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 782                 break;
 783         }
 784 }
 785
 786 static void
 787 new_socket(sock_type type, int fd)
 788 {
 789         u_int i, old_alloc, new_alloc;
 790
 791         set_nonblock(fd);
 792
 793         if (fd > max_fd)
 794                 max_fd = fd;
 795
 796         for (i = 0; i < sockets_alloc; i++)
 797                 if (sockets[i].type == AUTH_UNUSED) {
 798                         sockets[i].fd = fd;
 799                         buffer_init(&sockets[i].input);
 800                         buffer_init(&sockets[i].output);
 801                         buffer_init(&sockets[i].request);
 802                         sockets[i].type = type;
 803                         return;
 804                 }
 805         old_alloc = sockets_alloc;
 806         new_alloc = sockets_alloc + 10;
 807         if (sockets)
 808                 sockets = xrealloc(sockets, new_alloc * sizeof(sockets[0]));
 809         else
 810                 sockets = xmalloc(new_alloc * sizeof(sockets[0]));
 811         for (i = old_alloc; i < new_alloc; i++)
 812                 sockets[i].type = AUTH_UNUSED;
 813         sockets_alloc = new_alloc;
 814         sockets[old_alloc].fd = fd;
 815         buffer_init(&sockets[old_alloc].input);
 816         buffer_init(&sockets[old_alloc].output);
 817         buffer_init(&sockets[old_alloc].request);
 818         sockets[old_alloc].type = type;
 819 }
 820
 821 static int
 822 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
 823 {
 824         u_int i, sz;
 825         int n = 0;
 826
 827         for (i = 0; i < sockets_alloc; i++) {
 828                 switch (sockets[i].type) {
 829                 case AUTH_SOCKET:
 830                 case AUTH_CONNECTION:
 831                         n = MAX(n, sockets[i].fd);
 832                         break;
 833                 case AUTH_UNUSED:
 834                         break;
 835                 default:
 836                         fatal("Unknown socket type %d", sockets[i].type);
 837                         break;
 838                 }
 839         }
 840
 841         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 842         if (*fdrp == NULL || sz > *nallocp) {
 843                 if (*fdrp)
 844                         xfree(*fdrp);
 845                 if (*fdwp)
 846                         xfree(*fdwp);
 847                 *fdrp = xmalloc(sz);
 848                 *fdwp = xmalloc(sz);
 849                 *nallocp = sz;
 850         }
 851         if (n < *fdl)
 852                 debug("XXX shrink: %d < %d", n, *fdl);
 853         *fdl = n;
 854         memset(*fdrp, 0, sz);
 855         memset(*fdwp, 0, sz);
 856
 857         for (i = 0; i < sockets_alloc; i++) {
 858                 switch (sockets[i].type) {
 859                 case AUTH_SOCKET:
 860                 case AUTH_CONNECTION:
 861                         FD_SET(sockets[i].fd, *fdrp);
 862                         if (buffer_len(&sockets[i].output) > 0)
 863                                 FD_SET(sockets[i].fd, *fdwp);
 864                         break;
 865                 default:
 866                         break;
 867                 }
 868         }
 869         return (1);
 870 }
 871
 872 static void
 873 after_select(fd_set *readset, fd_set *writeset)
 874 {
 875         struct sockaddr_un sunaddr;
 876         socklen_t slen;
 877         char buf[1024];
 878         int len, sock;
 879         u_int i;
 880         uid_t euid;
 881         gid_t egid;
 882
 883         for (i = 0; i < sockets_alloc; i++)
 884                 switch (sockets[i].type) {
 885                 case AUTH_UNUSED:
 886                         break;
 887                 case AUTH_SOCKET:
 888                         if (FD_ISSET(sockets[i].fd, readset)) {
 889                                 slen = sizeof(sunaddr);
 890                                 sock = accept(sockets[i].fd,
 891                                     (struct sockaddr *) &sunaddr, &slen);
 892                                 if (sock < 0) {
 893                                         error("accept from AUTH_SOCKET: %s",
 894                                             strerror(errno));
 895                                         break;
 896                                 }
 897                                 if (getpeereid(sock, &euid, &egid) < 0) {
 898                                         error("getpeereid %d failed: %s",
 899                                             sock, strerror(errno));
 900                                         close(sock);
 901                                         break;
 902                                 }
 903                                 if ((euid != 0) && (getuid() != euid)) {
 904                                         error("uid mismatch: "
 905                                             "peer euid %u != uid %u",
 906                                             (u_int) euid, (u_int) getuid());
 907                                         close(sock);
 908                                         break;
 909                                 }
 910                                 new_socket(AUTH_CONNECTION, sock);
 911                         }
 912                         break;
 913                 case AUTH_CONNECTION:
 914                         if (buffer_len(&sockets[i].output) > 0 &&
 915                             FD_ISSET(sockets[i].fd, writeset)) {
 916                                 do {
 917                                         len = write(sockets[i].fd,
 918                                             buffer_ptr(&sockets[i].output),
 919                                             buffer_len(&sockets[i].output));
 920                                         if (len == -1 && (errno == EAGAIN ||
 921                                             errno == EINTR))
 922                                                 continue;
 923                                         break;
 924                                 } while (1);
 925                                 if (len <= 0) {
 926                                         close_socket(&sockets[i]);
 927                                         break;
 928                                 }
 929                                 buffer_consume(&sockets[i].output, len);
 930                         }
 931                         if (FD_ISSET(sockets[i].fd, readset)) {
 932                                 do {
 933                                         len = read(sockets[i].fd, buf, sizeof(buf));
 934                                         if (len == -1 && (errno == EAGAIN ||
 935                                             errno == EINTR))
 936                                                 continue;
 937                                         break;
 938                                 } while (1);
 939                                 if (len <= 0) {
 940                                         close_socket(&sockets[i]);
 941                                         break;
 942                                 }
 943                                 buffer_append(&sockets[i].input, buf, len);
 944                                 process_message(&sockets[i]);
 945                         }
 946                         break;
 947                 default:
 948                         fatal("Unknown type %d", sockets[i].type);
 949                 }
 950 }
 951
 952 static void
 953 cleanup_socket(void)
 954 {
 955         if (socket_name[0])
 956                 unlink(socket_name);
 957         if (socket_dir[0])
 958                 rmdir(socket_dir);
 959 }
 960
 961 void
 962 cleanup_exit(int i)
 963 {
 964         cleanup_socket();
 965         _exit(i);
 966 }
 967
 968 static void
 969 cleanup_handler(int sig)
 970 {
 971         cleanup_socket();
 972         _exit(2);
 973 }
 974
 975 static void
 976 check_parent_exists(int sig)
 977 {
 978         int save_errno = errno;
 979
 980         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 981                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 982                 cleanup_handler(sig); /* safe */
 983         }
 984         mysignal(SIGALRM, check_parent_exists);
 985         alarm(10);
 986         errno = save_errno;
 987 }
 988
 989 static void
 990 usage(void)
 991 {
 992         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 993             __progname);
 994         fprintf(stderr, "Options:\n");
 995         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 996         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 997         fprintf(stderr, "  -k          Kill the current agent.\n");
 998         fprintf(stderr, "  -d          Debug mode.\n");
 999         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1000         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1001         exit(1);
1002 }
1003
1004 int
1005 main(int ac, char **av)
1006 {
1007         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1008         int sock, fd,  ch;
1009         u_int nalloc;
1010         char *shell, *format, *pidstr, *agentsocket = NULL;
1011         fd_set *readsetp = NULL, *writesetp = NULL;
1012         struct sockaddr_un sunaddr;
1013 #ifdef HAVE_SETRLIMIT
1014         struct rlimit rlim;
1015 #endif
1016         int prev_mask;
1017         extern int optind;
1018         extern char *optarg;
1019         pid_t pid;
1020         char pidstrbuf[1 + 3 * sizeof pid];
1021
1022         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1023         sanitise_stdfd();
1024
1025         /* drop */
1026         setegid(getgid());
1027         setgid(getgid());
1028
1029 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1030         /* Disable ptrace on Linux without sgid bit */
1031         prctl(PR_SET_DUMPABLE, 0);
1032 #endif
1033
1034         SSLeay_add_all_algorithms();
1035
1036         __progname = ssh_get_progname(av[0]);
1037         init_rng();
1038         seed_rng();
1039
1040         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1041                 switch (ch) {
1042                 case 'c':
1043                         if (s_flag)
1044                                 usage();
1045                         c_flag++;
1046                         break;
1047                 case 'k':
1048                         k_flag++;
1049                         break;
1050                 case 's':
1051                         if (c_flag)
1052                                 usage();
1053                         s_flag++;
1054                         break;
1055                 case 'd':
1056                         if (d_flag)
1057                                 usage();
1058                         d_flag++;
1059                         break;
1060                 case 'a':
1061                         agentsocket = optarg;
1062                         break;
1063                 case 't':
1064                         if ((lifetime = convtime(optarg)) == -1) {
1065                                 fprintf(stderr, "Invalid lifetime\n");
1066                                 usage();
1067                         }
1068                         break;
1069                 default:
1070                         usage();
1071                 }
1072         }
1073         ac -= optind;
1074         av += optind;
1075
1076         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1077                 usage();
1078
1079         if (ac == 0 && !c_flag && !s_flag) {
1080                 shell = getenv("SHELL");
1081                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1082                         c_flag = 1;
1083         }
1084         if (k_flag) {
1085                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1086                 if (pidstr == NULL) {
1087                         fprintf(stderr, "%s not set, cannot kill agent\n",
1088                             SSH_AGENTPID_ENV_NAME);
1089                         exit(1);
1090                 }
1091                 pid = atoi(pidstr);
1092                 if (pid < 1) {
1093                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
1094                             SSH_AGENTPID_ENV_NAME, pidstr);
1095                         exit(1);
1096                 }
1097                 if (kill(pid, SIGTERM) == -1) {
1098                         perror("kill");
1099                         exit(1);
1100                 }
1101                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1102                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1103                 printf(format, SSH_AGENTPID_ENV_NAME);
1104                 printf("echo Agent pid %ld killed;\n", (long)pid);
1105                 exit(0);
1106         }
1107         parent_pid = getpid();
1108
1109         if (agentsocket == NULL) {
1110                 /* Create private directory for agent socket */
1111                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1112                 if (mkdtemp(socket_dir) == NULL) {
1113                         perror("mkdtemp: private socket dir");
1114                         exit(1);
1115                 }
1116                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1117                     (long)parent_pid);
1118         } else {
1119                 /* Try to use specified agent socket */
1120                 socket_dir[0] = '\0';
1121                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1122         }
1123
1124         /*
1125          * Create socket early so it will exist before command gets run from
1126          * the parent.
1127          */
1128         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1129         if (sock < 0) {
1130                 perror("socket");
1131                 *socket_name = '\0'; /* Don't unlink any existing file */
1132                 cleanup_exit(1);
1133         }
1134         memset(&sunaddr, 0, sizeof(sunaddr));
1135         sunaddr.sun_family = AF_UNIX;
1136         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1137         prev_mask = umask(0177);
1138         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1139                 perror("bind");
1140                 *socket_name = '\0'; /* Don't unlink any existing file */
1141                 umask(prev_mask);
1142                 cleanup_exit(1);
1143         }
1144         umask(prev_mask);
1145         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1146                 perror("listen");
1147                 cleanup_exit(1);
1148         }
1149
1150         /*
1151          * Fork, and have the parent execute the command, if any, or present
1152          * the socket data.  The child continues as the authentication agent.
1153          */
1154         if (d_flag) {
1155                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1156                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1157                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1158                     SSH_AUTHSOCKET_ENV_NAME);
1159                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1160                 goto skip;
1161         }
1162         pid = fork();
1163         if (pid == -1) {
1164                 perror("fork");
1165                 cleanup_exit(1);
1166         }
1167         if (pid != 0) {         /* Parent - execute the given command. */
1168                 close(sock);
1169                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1170                 if (ac == 0) {
1171                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1172                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1173                             SSH_AUTHSOCKET_ENV_NAME);
1174                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1175                             SSH_AGENTPID_ENV_NAME);
1176                         printf("echo Agent pid %ld;\n", (long)pid);
1177                         exit(0);
1178                 }
1179                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1180                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1181                         perror("setenv");
1182                         exit(1);
1183                 }
1184                 execvp(av[0], av);
1185                 perror(av[0]);
1186                 exit(1);
1187         }
1188         /* child */
1189         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1190
1191         if (setsid() == -1) {
1192                 error("setsid: %s", strerror(errno));
1193                 cleanup_exit(1);
1194         }
1195
1196         (void)chdir("/");
1197         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1198                 /* XXX might close listen socket */
1199                 (void)dup2(fd, STDIN_FILENO);
1200                 (void)dup2(fd, STDOUT_FILENO);
1201                 (void)dup2(fd, STDERR_FILENO);
1202                 if (fd > 2)
1203                         close(fd);
1204         }
1205
1206 #ifdef HAVE_SETRLIMIT
1207         /* deny core dumps, since memory contains unencrypted private keys */
1208         rlim.rlim_cur = rlim.rlim_max = 0;
1209         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1210                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1211                 cleanup_exit(1);
1212         }
1213 #endif
1214
1215 skip:
1216         new_socket(AUTH_SOCKET, sock);
1217         if (ac > 0) {
1218                 mysignal(SIGALRM, check_parent_exists);
1219                 alarm(10);
1220         }
1221         idtab_init();
1222         if (!d_flag)
1223                 signal(SIGINT, SIG_IGN);
1224         signal(SIGPIPE, SIG_IGN);
1225         signal(SIGHUP, cleanup_handler);
1226         signal(SIGTERM, cleanup_handler);
1227         nalloc = 0;
1228
1229         while (1) {
1230                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1231                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1232                         if (errno == EINTR)
1233                                 continue;
1234                         fatal("select: %s", strerror(errno));
1235                 }
1236                 after_select(readsetp, writesetp);
1237         }
1238         /* NOTREACHED */
1239 }