ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.145 2006/07/22 19:08:54 stevesk 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 #include <sys/socket.h>
  42 #ifdef HAVE_SYS_UN_H
  43 # include <sys/un.h>
  44 #endif
  45 #include "openbsd-compat/sys-queue.h"
  46 #include <sys/resource.h>
  47
  48 #include <errno.h>
  49 #include <fcntl.h>
  50 #ifdef HAVE_PATHS_H
  51 # include <paths.h>
  52 #endif
  53 #include <signal.h>
  54 #include <time.h>
  55 #include <unistd.h>
  56
  57 #include <openssl/evp.h>
  58 #include <openssl/md5.h>
  59
  60 #include "ssh.h"
  61 #include "rsa.h"
  62 #include "buffer.h"
  63 #include "bufaux.h"
  64 #include "xmalloc.h"
  65 #include "key.h"
  66 #include "authfd.h"
  67 #include "compat.h"
  68 #include "log.h"
  69 #include "misc.h"
  70
  71 #ifdef SMARTCARD
  72 #include "scard.h"
  73 #endif
  74
  75 #if defined(HAVE_SYS_PRCTL_H)
  76 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  77 #endif
  78
  79 typedef enum {
  80         AUTH_UNUSED,
  81         AUTH_SOCKET,
  82         AUTH_CONNECTION
  83 } sock_type;
  84
  85 typedef struct {
  86         int fd;
  87         sock_type type;
  88         Buffer input;
  89         Buffer output;
  90         Buffer request;
  91 } SocketEntry;
  92
  93 u_int sockets_alloc = 0;
  94 SocketEntry *sockets = NULL;
  95
  96 typedef struct identity {
  97         TAILQ_ENTRY(identity) next;
  98         Key *key;
  99         char *comment;
 100         u_int death;
 101         u_int confirm;
 102 } Identity;
 103
 104 typedef struct {
 105         int nentries;
 106         TAILQ_HEAD(idqueue, identity) idlist;
 107 } Idtab;
 108
 109 /* private key table, one per protocol version */
 110 Idtab idtable[3];
 111
 112 int max_fd = 0;
 113
 114 /* pid of shell == parent of agent */
 115 pid_t parent_pid = -1;
 116
 117 /* pathname and directory for AUTH_SOCKET */
 118 char socket_name[MAXPATHLEN];
 119 char socket_dir[MAXPATHLEN];
 120
 121 /* locking */
 122 int locked = 0;
 123 char *lock_passwd = NULL;
 124
 125 extern char *__progname;
 126
 127 /* Default lifetime (0 == forever) */
 128 static int lifetime = 0;
 129
 130 static void
 131 close_socket(SocketEntry *e)
 132 {
 133         close(e->fd);
 134         e->fd = -1;
 135         e->type = AUTH_UNUSED;
 136         buffer_free(&e->input);
 137         buffer_free(&e->output);
 138         buffer_free(&e->request);
 139 }
 140
 141 static void
 142 idtab_init(void)
 143 {
 144         int i;
 145
 146         for (i = 0; i <=2; i++) {
 147                 TAILQ_INIT(&idtable[i].idlist);
 148                 idtable[i].nentries = 0;
 149         }
 150 }
 151
 152 /* return private key table for requested protocol version */
 153 static Idtab *
 154 idtab_lookup(int version)
 155 {
 156         if (version < 1 || version > 2)
 157                 fatal("internal error, bad protocol version %d", version);
 158         return &idtable[version];
 159 }
 160
 161 static void
 162 free_identity(Identity *id)
 163 {
 164         key_free(id->key);
 165         xfree(id->comment);
 166         xfree(id);
 167 }
 168
 169 /* return matching private key for given public key */
 170 static Identity *
 171 lookup_identity(Key *key, int version)
 172 {
 173         Identity *id;
 174
 175         Idtab *tab = idtab_lookup(version);
 176         TAILQ_FOREACH(id, &tab->idlist, next) {
 177                 if (key_equal(key, id->key))
 178                         return (id);
 179         }
 180         return (NULL);
 181 }
 182
 183 /* Check confirmation of keysign request */
 184 static int
 185 confirm_key(Identity *id)
 186 {
 187         char *p;
 188         int ret = -1;
 189
 190         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 191         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 192             id->comment, p))
 193                 ret = 0;
 194         xfree(p);
 195
 196         return (ret);
 197 }
 198
 199 /* send list of supported public keys to 'client' */
 200 static void
 201 process_request_identities(SocketEntry *e, int version)
 202 {
 203         Idtab *tab = idtab_lookup(version);
 204         Identity *id;
 205         Buffer msg;
 206
 207         buffer_init(&msg);
 208         buffer_put_char(&msg, (version == 1) ?
 209             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 210         buffer_put_int(&msg, tab->nentries);
 211         TAILQ_FOREACH(id, &tab->idlist, next) {
 212                 if (id->key->type == KEY_RSA1) {
 213                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 214                         buffer_put_bignum(&msg, id->key->rsa->e);
 215                         buffer_put_bignum(&msg, id->key->rsa->n);
 216                 } else {
 217                         u_char *blob;
 218                         u_int blen;
 219                         key_to_blob(id->key, &blob, &blen);
 220                         buffer_put_string(&msg, blob, blen);
 221                         xfree(blob);
 222                 }
 223                 buffer_put_cstring(&msg, id->comment);
 224         }
 225         buffer_put_int(&e->output, buffer_len(&msg));
 226         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 227         buffer_free(&msg);
 228 }
 229
 230 /* ssh1 only */
 231 static void
 232 process_authentication_challenge1(SocketEntry *e)
 233 {
 234         u_char buf[32], mdbuf[16], session_id[16];
 235         u_int response_type;
 236         BIGNUM *challenge;
 237         Identity *id;
 238         int i, len;
 239         Buffer msg;
 240         MD5_CTX md;
 241         Key *key;
 242
 243         buffer_init(&msg);
 244         key = key_new(KEY_RSA1);
 245         if ((challenge = BN_new()) == NULL)
 246                 fatal("process_authentication_challenge1: BN_new failed");
 247
 248         (void) buffer_get_int(&e->request);                     /* ignored */
 249         buffer_get_bignum(&e->request, key->rsa->e);
 250         buffer_get_bignum(&e->request, key->rsa->n);
 251         buffer_get_bignum(&e->request, challenge);
 252
 253         /* Only protocol 1.1 is supported */
 254         if (buffer_len(&e->request) == 0)
 255                 goto failure;
 256         buffer_get(&e->request, session_id, 16);
 257         response_type = buffer_get_int(&e->request);
 258         if (response_type != 1)
 259                 goto failure;
 260
 261         id = lookup_identity(key, 1);
 262         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 263                 Key *private = id->key;
 264                 /* Decrypt the challenge using the private key. */
 265                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 266                         goto failure;
 267
 268                 /* The response is MD5 of decrypted challenge plus session id. */
 269                 len = BN_num_bytes(challenge);
 270                 if (len <= 0 || len > 32) {
 271                         logit("process_authentication_challenge: bad challenge length %d", len);
 272                         goto failure;
 273                 }
 274                 memset(buf, 0, 32);
 275                 BN_bn2bin(challenge, buf + 32 - len);
 276                 MD5_Init(&md);
 277                 MD5_Update(&md, buf, 32);
 278                 MD5_Update(&md, session_id, 16);
 279                 MD5_Final(mdbuf, &md);
 280
 281                 /* Send the response. */
 282                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 283                 for (i = 0; i < 16; i++)
 284                         buffer_put_char(&msg, mdbuf[i]);
 285                 goto send;
 286         }
 287
 288 failure:
 289         /* Unknown identity or protocol error.  Send failure. */
 290         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 291 send:
 292         buffer_put_int(&e->output, buffer_len(&msg));
 293         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 294         key_free(key);
 295         BN_clear_free(challenge);
 296         buffer_free(&msg);
 297 }
 298
 299 /* ssh2 only */
 300 static void
 301 process_sign_request2(SocketEntry *e)
 302 {
 303         u_char *blob, *data, *signature = NULL;
 304         u_int blen, dlen, slen = 0;
 305         extern int datafellows;
 306         int ok = -1, flags;
 307         Buffer msg;
 308         Key *key;
 309
 310         datafellows = 0;
 311
 312         blob = buffer_get_string(&e->request, &blen);
 313         data = buffer_get_string(&e->request, &dlen);
 314
 315         flags = buffer_get_int(&e->request);
 316         if (flags & SSH_AGENT_OLD_SIGNATURE)
 317                 datafellows = SSH_BUG_SIGBLOB;
 318
 319         key = key_from_blob(blob, blen);
 320         if (key != NULL) {
 321                 Identity *id = lookup_identity(key, 2);
 322                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 323                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 324                 key_free(key);
 325         }
 326         buffer_init(&msg);
 327         if (ok == 0) {
 328                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 329                 buffer_put_string(&msg, signature, slen);
 330         } else {
 331                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 332         }
 333         buffer_put_int(&e->output, buffer_len(&msg));
 334         buffer_append(&e->output, buffer_ptr(&msg),
 335             buffer_len(&msg));
 336         buffer_free(&msg);
 337         xfree(data);
 338         xfree(blob);
 339         if (signature != NULL)
 340                 xfree(signature);
 341 }
 342
 343 /* shared */
 344 static void
 345 process_remove_identity(SocketEntry *e, int version)
 346 {
 347         u_int blen, bits;
 348         int success = 0;
 349         Key *key = NULL;
 350         u_char *blob;
 351
 352         switch (version) {
 353         case 1:
 354                 key = key_new(KEY_RSA1);
 355                 bits = buffer_get_int(&e->request);
 356                 buffer_get_bignum(&e->request, key->rsa->e);
 357                 buffer_get_bignum(&e->request, key->rsa->n);
 358
 359                 if (bits != key_size(key))
 360                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 361                             key_size(key), bits);
 362                 break;
 363         case 2:
 364                 blob = buffer_get_string(&e->request, &blen);
 365                 key = key_from_blob(blob, blen);
 366                 xfree(blob);
 367                 break;
 368         }
 369         if (key != NULL) {
 370                 Identity *id = lookup_identity(key, version);
 371                 if (id != NULL) {
 372                         /*
 373                          * We have this key.  Free the old key.  Since we
 374                          * don't want to leave empty slots in the middle of
 375                          * the array, we actually free the key there and move
 376                          * all the entries between the empty slot and the end
 377                          * of the array.
 378                          */
 379                         Idtab *tab = idtab_lookup(version);
 380                         if (tab->nentries < 1)
 381                                 fatal("process_remove_identity: "
 382                                     "internal error: tab->nentries %d",
 383                                     tab->nentries);
 384                         TAILQ_REMOVE(&tab->idlist, id, next);
 385                         free_identity(id);
 386                         tab->nentries--;
 387                         success = 1;
 388                 }
 389                 key_free(key);
 390         }
 391         buffer_put_int(&e->output, 1);
 392         buffer_put_char(&e->output,
 393             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 394 }
 395
 396 static void
 397 process_remove_all_identities(SocketEntry *e, int version)
 398 {
 399         Idtab *tab = idtab_lookup(version);
 400         Identity *id;
 401
 402         /* Loop over all identities and clear the keys. */
 403         for (id = TAILQ_FIRST(&tab->idlist); id;
 404             id = TAILQ_FIRST(&tab->idlist)) {
 405                 TAILQ_REMOVE(&tab->idlist, id, next);
 406                 free_identity(id);
 407         }
 408
 409         /* Mark that there are no identities. */
 410         tab->nentries = 0;
 411
 412         /* Send success. */
 413         buffer_put_int(&e->output, 1);
 414         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 415 }
 416
 417 static void
 418 reaper(void)
 419 {
 420         u_int now = time(NULL);
 421         Identity *id, *nxt;
 422         int version;
 423         Idtab *tab;
 424
 425         for (version = 1; version < 3; version++) {
 426                 tab = idtab_lookup(version);
 427                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 428                         nxt = TAILQ_NEXT(id, next);
 429                         if (id->death != 0 && now >= id->death) {
 430                                 TAILQ_REMOVE(&tab->idlist, id, next);
 431                                 free_identity(id);
 432                                 tab->nentries--;
 433                         }
 434                 }
 435         }
 436 }
 437
 438 static void
 439 process_add_identity(SocketEntry *e, int version)
 440 {
 441         Idtab *tab = idtab_lookup(version);
 442         int type, success = 0, death = 0, confirm = 0;
 443         char *type_name, *comment;
 444         Key *k = NULL;
 445
 446         switch (version) {
 447         case 1:
 448                 k = key_new_private(KEY_RSA1);
 449                 (void) buffer_get_int(&e->request);             /* ignored */
 450                 buffer_get_bignum(&e->request, k->rsa->n);
 451                 buffer_get_bignum(&e->request, k->rsa->e);
 452                 buffer_get_bignum(&e->request, k->rsa->d);
 453                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 454
 455                 /* SSH and SSL have p and q swapped */
 456                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 457                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 458
 459                 /* Generate additional parameters */
 460                 rsa_generate_additional_parameters(k->rsa);
 461                 break;
 462         case 2:
 463                 type_name = buffer_get_string(&e->request, NULL);
 464                 type = key_type_from_name(type_name);
 465                 xfree(type_name);
 466                 switch (type) {
 467                 case KEY_DSA:
 468                         k = key_new_private(type);
 469                         buffer_get_bignum2(&e->request, k->dsa->p);
 470                         buffer_get_bignum2(&e->request, k->dsa->q);
 471                         buffer_get_bignum2(&e->request, k->dsa->g);
 472                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 473                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 474                         break;
 475                 case KEY_RSA:
 476                         k = key_new_private(type);
 477                         buffer_get_bignum2(&e->request, k->rsa->n);
 478                         buffer_get_bignum2(&e->request, k->rsa->e);
 479                         buffer_get_bignum2(&e->request, k->rsa->d);
 480                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 481                         buffer_get_bignum2(&e->request, k->rsa->p);
 482                         buffer_get_bignum2(&e->request, k->rsa->q);
 483
 484                         /* Generate additional parameters */
 485                         rsa_generate_additional_parameters(k->rsa);
 486                         break;
 487                 default:
 488                         buffer_clear(&e->request);
 489                         goto send;
 490                 }
 491                 break;
 492         }
 493         /* enable blinding */
 494         switch (k->type) {
 495         case KEY_RSA:
 496         case KEY_RSA1:
 497                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 498                         error("process_add_identity: RSA_blinding_on failed");
 499                         key_free(k);
 500                         goto send;
 501                 }
 502                 break;
 503         }
 504         comment = buffer_get_string(&e->request, NULL);
 505         if (k == NULL) {
 506                 xfree(comment);
 507                 goto send;
 508         }
 509         success = 1;
 510         while (buffer_len(&e->request)) {
 511                 switch (buffer_get_char(&e->request)) {
 512                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 513                         death = time(NULL) + buffer_get_int(&e->request);
 514                         break;
 515                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 516                         confirm = 1;
 517                         break;
 518                 default:
 519                         break;
 520                 }
 521         }
 522         if (lifetime && !death)
 523                 death = time(NULL) + lifetime;
 524         if (lookup_identity(k, version) == NULL) {
 525                 Identity *id = xmalloc(sizeof(Identity));
 526                 id->key = k;
 527                 id->comment = comment;
 528                 id->death = death;
 529                 id->confirm = confirm;
 530                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 531                 /* Increment the number of identities. */
 532                 tab->nentries++;
 533         } else {
 534                 key_free(k);
 535                 xfree(comment);
 536         }
 537 send:
 538         buffer_put_int(&e->output, 1);
 539         buffer_put_char(&e->output,
 540             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 541 }
 542
 543 /* XXX todo: encrypt sensitive data with passphrase */
 544 static void
 545 process_lock_agent(SocketEntry *e, int lock)
 546 {
 547         int success = 0;
 548         char *passwd;
 549
 550         passwd = buffer_get_string(&e->request, NULL);
 551         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 552                 locked = 0;
 553                 memset(lock_passwd, 0, strlen(lock_passwd));
 554                 xfree(lock_passwd);
 555                 lock_passwd = NULL;
 556                 success = 1;
 557         } else if (!locked && lock) {
 558                 locked = 1;
 559                 lock_passwd = xstrdup(passwd);
 560                 success = 1;
 561         }
 562         memset(passwd, 0, strlen(passwd));
 563         xfree(passwd);
 564
 565         buffer_put_int(&e->output, 1);
 566         buffer_put_char(&e->output,
 567             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 568 }
 569
 570 static void
 571 no_identities(SocketEntry *e, u_int type)
 572 {
 573         Buffer msg;
 574
 575         buffer_init(&msg);
 576         buffer_put_char(&msg,
 577             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 578             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 579         buffer_put_int(&msg, 0);
 580         buffer_put_int(&e->output, buffer_len(&msg));
 581         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 582         buffer_free(&msg);
 583 }
 584
 585 #ifdef SMARTCARD
 586 static void
 587 process_add_smartcard_key (SocketEntry *e)
 588 {
 589         char *sc_reader_id = NULL, *pin;
 590         int i, version, success = 0, death = 0, confirm = 0;
 591         Key **keys, *k;
 592         Identity *id;
 593         Idtab *tab;
 594
 595         sc_reader_id = buffer_get_string(&e->request, NULL);
 596         pin = buffer_get_string(&e->request, NULL);
 597
 598         while (buffer_len(&e->request)) {
 599                 switch (buffer_get_char(&e->request)) {
 600                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 601                         death = time(NULL) + buffer_get_int(&e->request);
 602                         break;
 603                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 604                         confirm = 1;
 605                         break;
 606                 default:
 607                         break;
 608                 }
 609         }
 610         if (lifetime && !death)
 611                 death = time(NULL) + lifetime;
 612
 613         keys = sc_get_keys(sc_reader_id, pin);
 614         xfree(sc_reader_id);
 615         xfree(pin);
 616
 617         if (keys == NULL || keys[0] == NULL) {
 618                 error("sc_get_keys failed");
 619                 goto send;
 620         }
 621         for (i = 0; keys[i] != NULL; i++) {
 622                 k = keys[i];
 623                 version = k->type == KEY_RSA1 ? 1 : 2;
 624                 tab = idtab_lookup(version);
 625                 if (lookup_identity(k, version) == NULL) {
 626                         id = xmalloc(sizeof(Identity));
 627                         id->key = k;
 628                         id->comment = sc_get_key_label(k);
 629                         id->death = death;
 630                         id->confirm = confirm;
 631                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 632                         tab->nentries++;
 633                         success = 1;
 634                 } else {
 635                         key_free(k);
 636                 }
 637                 keys[i] = NULL;
 638         }
 639         xfree(keys);
 640 send:
 641         buffer_put_int(&e->output, 1);
 642         buffer_put_char(&e->output,
 643             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 644 }
 645
 646 static void
 647 process_remove_smartcard_key(SocketEntry *e)
 648 {
 649         char *sc_reader_id = NULL, *pin;
 650         int i, version, success = 0;
 651         Key **keys, *k = NULL;
 652         Identity *id;
 653         Idtab *tab;
 654
 655         sc_reader_id = buffer_get_string(&e->request, NULL);
 656         pin = buffer_get_string(&e->request, NULL);
 657         keys = sc_get_keys(sc_reader_id, pin);
 658         xfree(sc_reader_id);
 659         xfree(pin);
 660
 661         if (keys == NULL || keys[0] == NULL) {
 662                 error("sc_get_keys failed");
 663                 goto send;
 664         }
 665         for (i = 0; keys[i] != NULL; i++) {
 666                 k = keys[i];
 667                 version = k->type == KEY_RSA1 ? 1 : 2;
 668                 if ((id = lookup_identity(k, version)) != NULL) {
 669                         tab = idtab_lookup(version);
 670                         TAILQ_REMOVE(&tab->idlist, id, next);
 671                         tab->nentries--;
 672                         free_identity(id);
 673                         success = 1;
 674                 }
 675                 key_free(k);
 676                 keys[i] = NULL;
 677         }
 678         xfree(keys);
 679 send:
 680         buffer_put_int(&e->output, 1);
 681         buffer_put_char(&e->output,
 682             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 683 }
 684 #endif /* SMARTCARD */
 685
 686 /* dispatch incoming messages */
 687
 688 static void
 689 process_message(SocketEntry *e)
 690 {
 691         u_int msg_len, type;
 692         u_char *cp;
 693
 694         /* kill dead keys */
 695         reaper();
 696
 697         if (buffer_len(&e->input) < 5)
 698                 return;         /* Incomplete message. */
 699         cp = buffer_ptr(&e->input);
 700         msg_len = get_u32(cp);
 701         if (msg_len > 256 * 1024) {
 702                 close_socket(e);
 703                 return;
 704         }
 705         if (buffer_len(&e->input) < msg_len + 4)
 706                 return;
 707
 708         /* move the current input to e->request */
 709         buffer_consume(&e->input, 4);
 710         buffer_clear(&e->request);
 711         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 712         buffer_consume(&e->input, msg_len);
 713         type = buffer_get_char(&e->request);
 714
 715         /* check wheter agent is locked */
 716         if (locked && type != SSH_AGENTC_UNLOCK) {
 717                 buffer_clear(&e->request);
 718                 switch (type) {
 719                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 720                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 721                         /* send empty lists */
 722                         no_identities(e, type);
 723                         break;
 724                 default:
 725                         /* send a fail message for all other request types */
 726                         buffer_put_int(&e->output, 1);
 727                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 728                 }
 729                 return;
 730         }
 731
 732         debug("type %d", type);
 733         switch (type) {
 734         case SSH_AGENTC_LOCK:
 735         case SSH_AGENTC_UNLOCK:
 736                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 737                 break;
 738         /* ssh1 */
 739         case SSH_AGENTC_RSA_CHALLENGE:
 740                 process_authentication_challenge1(e);
 741                 break;
 742         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 743                 process_request_identities(e, 1);
 744                 break;
 745         case SSH_AGENTC_ADD_RSA_IDENTITY:
 746         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 747                 process_add_identity(e, 1);
 748                 break;
 749         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 750                 process_remove_identity(e, 1);
 751                 break;
 752         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 753                 process_remove_all_identities(e, 1);
 754                 break;
 755         /* ssh2 */
 756         case SSH2_AGENTC_SIGN_REQUEST:
 757                 process_sign_request2(e);
 758                 break;
 759         case SSH2_AGENTC_REQUEST_IDENTITIES:
 760                 process_request_identities(e, 2);
 761                 break;
 762         case SSH2_AGENTC_ADD_IDENTITY:
 763         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 764                 process_add_identity(e, 2);
 765                 break;
 766         case SSH2_AGENTC_REMOVE_IDENTITY:
 767                 process_remove_identity(e, 2);
 768                 break;
 769         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 770                 process_remove_all_identities(e, 2);
 771                 break;
 772 #ifdef SMARTCARD
 773         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 774         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 775                 process_add_smartcard_key(e);
 776                 break;
 777         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 778                 process_remove_smartcard_key(e);
 779                 break;
 780 #endif /* SMARTCARD */
 781         default:
 782                 /* Unknown message.  Respond with failure. */
 783                 error("Unknown message %d", type);
 784                 buffer_clear(&e->request);
 785                 buffer_put_int(&e->output, 1);
 786                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 787                 break;
 788         }
 789 }
 790
 791 static void
 792 new_socket(sock_type type, int fd)
 793 {
 794         u_int i, old_alloc, new_alloc;
 795
 796         set_nonblock(fd);
 797
 798         if (fd > max_fd)
 799                 max_fd = fd;
 800
 801         for (i = 0; i < sockets_alloc; i++)
 802                 if (sockets[i].type == AUTH_UNUSED) {
 803                         sockets[i].fd = fd;
 804                         buffer_init(&sockets[i].input);
 805                         buffer_init(&sockets[i].output);
 806                         buffer_init(&sockets[i].request);
 807                         sockets[i].type = type;
 808                         return;
 809                 }
 810         old_alloc = sockets_alloc;
 811         new_alloc = sockets_alloc + 10;
 812         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 813         for (i = old_alloc; i < new_alloc; i++)
 814                 sockets[i].type = AUTH_UNUSED;
 815         sockets_alloc = new_alloc;
 816         sockets[old_alloc].fd = fd;
 817         buffer_init(&sockets[old_alloc].input);
 818         buffer_init(&sockets[old_alloc].output);
 819         buffer_init(&sockets[old_alloc].request);
 820         sockets[old_alloc].type = type;
 821 }
 822
 823 static int
 824 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
 825 {
 826         u_int i, sz;
 827         int n = 0;
 828
 829         for (i = 0; i < sockets_alloc; i++) {
 830                 switch (sockets[i].type) {
 831                 case AUTH_SOCKET:
 832                 case AUTH_CONNECTION:
 833                         n = MAX(n, sockets[i].fd);
 834                         break;
 835                 case AUTH_UNUSED:
 836                         break;
 837                 default:
 838                         fatal("Unknown socket type %d", sockets[i].type);
 839                         break;
 840                 }
 841         }
 842
 843         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 844         if (*fdrp == NULL || sz > *nallocp) {
 845                 if (*fdrp)
 846                         xfree(*fdrp);
 847                 if (*fdwp)
 848                         xfree(*fdwp);
 849                 *fdrp = xmalloc(sz);
 850                 *fdwp = xmalloc(sz);
 851                 *nallocp = sz;
 852         }
 853         if (n < *fdl)
 854                 debug("XXX shrink: %d < %d", n, *fdl);
 855         *fdl = n;
 856         memset(*fdrp, 0, sz);
 857         memset(*fdwp, 0, sz);
 858
 859         for (i = 0; i < sockets_alloc; i++) {
 860                 switch (sockets[i].type) {
 861                 case AUTH_SOCKET:
 862                 case AUTH_CONNECTION:
 863                         FD_SET(sockets[i].fd, *fdrp);
 864                         if (buffer_len(&sockets[i].output) > 0)
 865                                 FD_SET(sockets[i].fd, *fdwp);
 866                         break;
 867                 default:
 868                         break;
 869                 }
 870         }
 871         return (1);
 872 }
 873
 874 static void
 875 after_select(fd_set *readset, fd_set *writeset)
 876 {
 877         struct sockaddr_un sunaddr;
 878         socklen_t slen;
 879         char buf[1024];
 880         int len, sock;
 881         u_int i;
 882         uid_t euid;
 883         gid_t egid;
 884
 885         for (i = 0; i < sockets_alloc; i++)
 886                 switch (sockets[i].type) {
 887                 case AUTH_UNUSED:
 888                         break;
 889                 case AUTH_SOCKET:
 890                         if (FD_ISSET(sockets[i].fd, readset)) {
 891                                 slen = sizeof(sunaddr);
 892                                 sock = accept(sockets[i].fd,
 893                                     (struct sockaddr *)&sunaddr, &slen);
 894                                 if (sock < 0) {
 895                                         error("accept from AUTH_SOCKET: %s",
 896                                             strerror(errno));
 897                                         break;
 898                                 }
 899                                 if (getpeereid(sock, &euid, &egid) < 0) {
 900                                         error("getpeereid %d failed: %s",
 901                                             sock, strerror(errno));
 902                                         close(sock);
 903                                         break;
 904                                 }
 905                                 if ((euid != 0) && (getuid() != euid)) {
 906                                         error("uid mismatch: "
 907                                             "peer euid %u != uid %u",
 908                                             (u_int) euid, (u_int) getuid());
 909                                         close(sock);
 910                                         break;
 911                                 }
 912                                 new_socket(AUTH_CONNECTION, sock);
 913                         }
 914                         break;
 915                 case AUTH_CONNECTION:
 916                         if (buffer_len(&sockets[i].output) > 0 &&
 917                             FD_ISSET(sockets[i].fd, writeset)) {
 918                                 do {
 919                                         len = write(sockets[i].fd,
 920                                             buffer_ptr(&sockets[i].output),
 921                                             buffer_len(&sockets[i].output));
 922                                         if (len == -1 && (errno == EAGAIN ||
 923                                             errno == EINTR))
 924                                                 continue;
 925                                         break;
 926                                 } while (1);
 927                                 if (len <= 0) {
 928                                         close_socket(&sockets[i]);
 929                                         break;
 930                                 }
 931                                 buffer_consume(&sockets[i].output, len);
 932                         }
 933                         if (FD_ISSET(sockets[i].fd, readset)) {
 934                                 do {
 935                                         len = read(sockets[i].fd, buf, sizeof(buf));
 936                                         if (len == -1 && (errno == EAGAIN ||
 937                                             errno == EINTR))
 938                                                 continue;
 939                                         break;
 940                                 } while (1);
 941                                 if (len <= 0) {
 942                                         close_socket(&sockets[i]);
 943                                         break;
 944                                 }
 945                                 buffer_append(&sockets[i].input, buf, len);
 946                                 process_message(&sockets[i]);
 947                         }
 948                         break;
 949                 default:
 950                         fatal("Unknown type %d", sockets[i].type);
 951                 }
 952 }
 953
 954 static void
 955 cleanup_socket(void)
 956 {
 957         if (socket_name[0])
 958                 unlink(socket_name);
 959         if (socket_dir[0])
 960                 rmdir(socket_dir);
 961 }
 962
 963 void
 964 cleanup_exit(int i)
 965 {
 966         cleanup_socket();
 967         _exit(i);
 968 }
 969
 970 /*ARGSUSED*/
 971 static void
 972 cleanup_handler(int sig)
 973 {
 974         cleanup_socket();
 975         _exit(2);
 976 }
 977
 978 /*ARGSUSED*/
 979 static void
 980 check_parent_exists(int sig)
 981 {
 982         int save_errno = errno;
 983
 984         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 985                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 986                 cleanup_handler(sig); /* safe */
 987         }
 988         mysignal(SIGALRM, check_parent_exists);
 989         alarm(10);
 990         errno = save_errno;
 991 }
 992
 993 static void
 994 usage(void)
 995 {
 996         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 997             __progname);
 998         fprintf(stderr, "Options:\n");
 999         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1000         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1001         fprintf(stderr, "  -k          Kill the current agent.\n");
1002         fprintf(stderr, "  -d          Debug mode.\n");
1003         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1004         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1005         exit(1);
1006 }
1007
1008 int
1009 main(int ac, char **av)
1010 {
1011         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1012         int sock, fd,  ch;
1013         u_int nalloc;
1014         char *shell, *format, *pidstr, *agentsocket = NULL;
1015         fd_set *readsetp = NULL, *writesetp = NULL;
1016         struct sockaddr_un sunaddr;
1017 #ifdef HAVE_SETRLIMIT
1018         struct rlimit rlim;
1019 #endif
1020         int prev_mask;
1021         extern int optind;
1022         extern char *optarg;
1023         pid_t pid;
1024         char pidstrbuf[1 + 3 * sizeof pid];
1025
1026         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1027         sanitise_stdfd();
1028
1029         /* drop */
1030         setegid(getgid());
1031         setgid(getgid());
1032
1033 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1034         /* Disable ptrace on Linux without sgid bit */
1035         prctl(PR_SET_DUMPABLE, 0);
1036 #endif
1037
1038         SSLeay_add_all_algorithms();
1039
1040         __progname = ssh_get_progname(av[0]);
1041         init_rng();
1042         seed_rng();
1043
1044         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1045                 switch (ch) {
1046                 case 'c':
1047                         if (s_flag)
1048                                 usage();
1049                         c_flag++;
1050                         break;
1051                 case 'k':
1052                         k_flag++;
1053                         break;
1054                 case 's':
1055                         if (c_flag)
1056                                 usage();
1057                         s_flag++;
1058                         break;
1059                 case 'd':
1060                         if (d_flag)
1061                                 usage();
1062                         d_flag++;
1063                         break;
1064                 case 'a':
1065                         agentsocket = optarg;
1066                         break;
1067                 case 't':
1068                         if ((lifetime = convtime(optarg)) == -1) {
1069                                 fprintf(stderr, "Invalid lifetime\n");
1070                                 usage();
1071                         }
1072                         break;
1073                 default:
1074                         usage();
1075                 }
1076         }
1077         ac -= optind;
1078         av += optind;
1079
1080         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1081                 usage();
1082
1083         if (ac == 0 && !c_flag && !s_flag) {
1084                 shell = getenv("SHELL");
1085                 if (shell != NULL &&
1086                     strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1087                         c_flag = 1;
1088         }
1089         if (k_flag) {
1090                 const char *errstr = NULL;
1091
1092                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1093                 if (pidstr == NULL) {
1094                         fprintf(stderr, "%s not set, cannot kill agent\n",
1095                             SSH_AGENTPID_ENV_NAME);
1096                         exit(1);
1097                 }
1098                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1099                 if (errstr) {
1100                         fprintf(stderr,
1101                             "%s=\"%s\", which is not a good PID: %s\n",
1102                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1103                         exit(1);
1104                 }
1105                 if (kill(pid, SIGTERM) == -1) {
1106                         perror("kill");
1107                         exit(1);
1108                 }
1109                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1110                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1111                 printf(format, SSH_AGENTPID_ENV_NAME);
1112                 printf("echo Agent pid %ld killed;\n", (long)pid);
1113                 exit(0);
1114         }
1115         parent_pid = getpid();
1116
1117         if (agentsocket == NULL) {
1118                 /* Create private directory for agent socket */
1119                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1120                 if (mkdtemp(socket_dir) == NULL) {
1121                         perror("mkdtemp: private socket dir");
1122                         exit(1);
1123                 }
1124                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1125                     (long)parent_pid);
1126         } else {
1127                 /* Try to use specified agent socket */
1128                 socket_dir[0] = '\0';
1129                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1130         }
1131
1132         /*
1133          * Create socket early so it will exist before command gets run from
1134          * the parent.
1135          */
1136         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1137         if (sock < 0) {
1138                 perror("socket");
1139                 *socket_name = '\0'; /* Don't unlink any existing file */
1140                 cleanup_exit(1);
1141         }
1142         memset(&sunaddr, 0, sizeof(sunaddr));
1143         sunaddr.sun_family = AF_UNIX;
1144         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1145         prev_mask = umask(0177);
1146         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1147                 perror("bind");
1148                 *socket_name = '\0'; /* Don't unlink any existing file */
1149                 umask(prev_mask);
1150                 cleanup_exit(1);
1151         }
1152         umask(prev_mask);
1153         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1154                 perror("listen");
1155                 cleanup_exit(1);
1156         }
1157
1158         /*
1159          * Fork, and have the parent execute the command, if any, or present
1160          * the socket data.  The child continues as the authentication agent.
1161          */
1162         if (d_flag) {
1163                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1164                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1165                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1166                     SSH_AUTHSOCKET_ENV_NAME);
1167                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1168                 goto skip;
1169         }
1170         pid = fork();
1171         if (pid == -1) {
1172                 perror("fork");
1173                 cleanup_exit(1);
1174         }
1175         if (pid != 0) {         /* Parent - execute the given command. */
1176                 close(sock);
1177                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1178                 if (ac == 0) {
1179                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1180                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1181                             SSH_AUTHSOCKET_ENV_NAME);
1182                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1183                             SSH_AGENTPID_ENV_NAME);
1184                         printf("echo Agent pid %ld;\n", (long)pid);
1185                         exit(0);
1186                 }
1187                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1188                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1189                         perror("setenv");
1190                         exit(1);
1191                 }
1192                 execvp(av[0], av);
1193                 perror(av[0]);
1194                 exit(1);
1195         }
1196         /* child */
1197         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1198
1199         if (setsid() == -1) {
1200                 error("setsid: %s", strerror(errno));
1201                 cleanup_exit(1);
1202         }
1203
1204         (void)chdir("/");
1205         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1206                 /* XXX might close listen socket */
1207                 (void)dup2(fd, STDIN_FILENO);
1208                 (void)dup2(fd, STDOUT_FILENO);
1209                 (void)dup2(fd, STDERR_FILENO);
1210                 if (fd > 2)
1211                         close(fd);
1212         }
1213
1214 #ifdef HAVE_SETRLIMIT
1215         /* deny core dumps, since memory contains unencrypted private keys */
1216         rlim.rlim_cur = rlim.rlim_max = 0;
1217         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1218                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1219                 cleanup_exit(1);
1220         }
1221 #endif
1222
1223 skip:
1224         new_socket(AUTH_SOCKET, sock);
1225         if (ac > 0) {
1226                 mysignal(SIGALRM, check_parent_exists);
1227                 alarm(10);
1228         }
1229         idtab_init();
1230         if (!d_flag)
1231                 signal(SIGINT, SIG_IGN);
1232         signal(SIGPIPE, SIG_IGN);
1233         signal(SIGHUP, cleanup_handler);
1234         signal(SIGTERM, cleanup_handler);
1235         nalloc = 0;
1236
1237         while (1) {
1238                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1239                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1240                         if (errno == EINTR)
1241                                 continue;
1242                         fatal("select: %s", strerror(errno));
1243                 }
1244                 after_select(readsetp, writesetp);
1245         }
1246         /* NOTREACHED */
1247 }