ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.146 2006/07/22 20:48:23 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 <openssl/evp.h>
  49 #include <openssl/md5.h>
  50
  51 #include <errno.h>
  52 #include <fcntl.h>
  53 #ifdef HAVE_PATHS_H
  54 # include <paths.h>
  55 #endif
  56 #include <signal.h>
  57 #include <time.h>
  58 #include <string.h>
  59 #include <unistd.h>
  60
  61 #include "ssh.h"
  62 #include "rsa.h"
  63 #include "buffer.h"
  64 #include "bufaux.h"
  65 #include "xmalloc.h"
  66 #include "key.h"
  67 #include "authfd.h"
  68 #include "compat.h"
  69 #include "log.h"
  70 #include "misc.h"
  71
  72 #ifdef SMARTCARD
  73 #include "scard.h"
  74 #endif
  75
  76 #if defined(HAVE_SYS_PRCTL_H)
  77 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  78 #endif
  79
  80 typedef enum {
  81         AUTH_UNUSED,
  82         AUTH_SOCKET,
  83         AUTH_CONNECTION
  84 } sock_type;
  85
  86 typedef struct {
  87         int fd;
  88         sock_type type;
  89         Buffer input;
  90         Buffer output;
  91         Buffer request;
  92 } SocketEntry;
  93
  94 u_int sockets_alloc = 0;
  95 SocketEntry *sockets = NULL;
  96
  97 typedef struct identity {
  98         TAILQ_ENTRY(identity) next;
  99         Key *key;
 100         char *comment;
 101         u_int death;
 102         u_int confirm;
 103 } Identity;
 104
 105 typedef struct {
 106         int nentries;
 107         TAILQ_HEAD(idqueue, identity) idlist;
 108 } Idtab;
 109
 110 /* private key table, one per protocol version */
 111 Idtab idtable[3];
 112
 113 int max_fd = 0;
 114
 115 /* pid of shell == parent of agent */
 116 pid_t parent_pid = -1;
 117
 118 /* pathname and directory for AUTH_SOCKET */
 119 char socket_name[MAXPATHLEN];
 120 char socket_dir[MAXPATHLEN];
 121
 122 /* locking */
 123 int locked = 0;
 124 char *lock_passwd = NULL;
 125
 126 extern char *__progname;
 127
 128 /* Default lifetime (0 == forever) */
 129 static int lifetime = 0;
 130
 131 static void
 132 close_socket(SocketEntry *e)
 133 {
 134         close(e->fd);
 135         e->fd = -1;
 136         e->type = AUTH_UNUSED;
 137         buffer_free(&e->input);
 138         buffer_free(&e->output);
 139         buffer_free(&e->request);
 140 }
 141
 142 static void
 143 idtab_init(void)
 144 {
 145         int i;
 146
 147         for (i = 0; i <=2; i++) {
 148                 TAILQ_INIT(&idtable[i].idlist);
 149                 idtable[i].nentries = 0;
 150         }
 151 }
 152
 153 /* return private key table for requested protocol version */
 154 static Idtab *
 155 idtab_lookup(int version)
 156 {
 157         if (version < 1 || version > 2)
 158                 fatal("internal error, bad protocol version %d", version);
 159         return &idtable[version];
 160 }
 161
 162 static void
 163 free_identity(Identity *id)
 164 {
 165         key_free(id->key);
 166         xfree(id->comment);
 167         xfree(id);
 168 }
 169
 170 /* return matching private key for given public key */
 171 static Identity *
 172 lookup_identity(Key *key, int version)
 173 {
 174         Identity *id;
 175
 176         Idtab *tab = idtab_lookup(version);
 177         TAILQ_FOREACH(id, &tab->idlist, next) {
 178                 if (key_equal(key, id->key))
 179                         return (id);
 180         }
 181         return (NULL);
 182 }
 183
 184 /* Check confirmation of keysign request */
 185 static int
 186 confirm_key(Identity *id)
 187 {
 188         char *p;
 189         int ret = -1;
 190
 191         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 192         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 193             id->comment, p))
 194                 ret = 0;
 195         xfree(p);
 196
 197         return (ret);
 198 }
 199
 200 /* send list of supported public keys to 'client' */
 201 static void
 202 process_request_identities(SocketEntry *e, int version)
 203 {
 204         Idtab *tab = idtab_lookup(version);
 205         Identity *id;
 206         Buffer msg;
 207
 208         buffer_init(&msg);
 209         buffer_put_char(&msg, (version == 1) ?
 210             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 211         buffer_put_int(&msg, tab->nentries);
 212         TAILQ_FOREACH(id, &tab->idlist, next) {
 213                 if (id->key->type == KEY_RSA1) {
 214                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 215                         buffer_put_bignum(&msg, id->key->rsa->e);
 216                         buffer_put_bignum(&msg, id->key->rsa->n);
 217                 } else {
 218                         u_char *blob;
 219                         u_int blen;
 220                         key_to_blob(id->key, &blob, &blen);
 221                         buffer_put_string(&msg, blob, blen);
 222                         xfree(blob);
 223                 }
 224                 buffer_put_cstring(&msg, id->comment);
 225         }
 226         buffer_put_int(&e->output, buffer_len(&msg));
 227         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 228         buffer_free(&msg);
 229 }
 230
 231 /* ssh1 only */
 232 static void
 233 process_authentication_challenge1(SocketEntry *e)
 234 {
 235         u_char buf[32], mdbuf[16], session_id[16];
 236         u_int response_type;
 237         BIGNUM *challenge;
 238         Identity *id;
 239         int i, len;
 240         Buffer msg;
 241         MD5_CTX md;
 242         Key *key;
 243
 244         buffer_init(&msg);
 245         key = key_new(KEY_RSA1);
 246         if ((challenge = BN_new()) == NULL)
 247                 fatal("process_authentication_challenge1: BN_new failed");
 248
 249         (void) buffer_get_int(&e->request);                     /* ignored */
 250         buffer_get_bignum(&e->request, key->rsa->e);
 251         buffer_get_bignum(&e->request, key->rsa->n);
 252         buffer_get_bignum(&e->request, challenge);
 253
 254         /* Only protocol 1.1 is supported */
 255         if (buffer_len(&e->request) == 0)
 256                 goto failure;
 257         buffer_get(&e->request, session_id, 16);
 258         response_type = buffer_get_int(&e->request);
 259         if (response_type != 1)
 260                 goto failure;
 261
 262         id = lookup_identity(key, 1);
 263         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 264                 Key *private = id->key;
 265                 /* Decrypt the challenge using the private key. */
 266                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 267                         goto failure;
 268
 269                 /* The response is MD5 of decrypted challenge plus session id. */
 270                 len = BN_num_bytes(challenge);
 271                 if (len <= 0 || len > 32) {
 272                         logit("process_authentication_challenge: bad challenge length %d", len);
 273                         goto failure;
 274                 }
 275                 memset(buf, 0, 32);
 276                 BN_bn2bin(challenge, buf + 32 - len);
 277                 MD5_Init(&md);
 278                 MD5_Update(&md, buf, 32);
 279                 MD5_Update(&md, session_id, 16);
 280                 MD5_Final(mdbuf, &md);
 281
 282                 /* Send the response. */
 283                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 284                 for (i = 0; i < 16; i++)
 285                         buffer_put_char(&msg, mdbuf[i]);
 286                 goto send;
 287         }
 288
 289 failure:
 290         /* Unknown identity or protocol error.  Send failure. */
 291         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 292 send:
 293         buffer_put_int(&e->output, buffer_len(&msg));
 294         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 295         key_free(key);
 296         BN_clear_free(challenge);
 297         buffer_free(&msg);
 298 }
 299
 300 /* ssh2 only */
 301 static void
 302 process_sign_request2(SocketEntry *e)
 303 {
 304         u_char *blob, *data, *signature = NULL;
 305         u_int blen, dlen, slen = 0;
 306         extern int datafellows;
 307         int ok = -1, flags;
 308         Buffer msg;
 309         Key *key;
 310
 311         datafellows = 0;
 312
 313         blob = buffer_get_string(&e->request, &blen);
 314         data = buffer_get_string(&e->request, &dlen);
 315
 316         flags = buffer_get_int(&e->request);
 317         if (flags & SSH_AGENT_OLD_SIGNATURE)
 318                 datafellows = SSH_BUG_SIGBLOB;
 319
 320         key = key_from_blob(blob, blen);
 321         if (key != NULL) {
 322                 Identity *id = lookup_identity(key, 2);
 323                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 324                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 325                 key_free(key);
 326         }
 327         buffer_init(&msg);
 328         if (ok == 0) {
 329                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 330                 buffer_put_string(&msg, signature, slen);
 331         } else {
 332                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 333         }
 334         buffer_put_int(&e->output, buffer_len(&msg));
 335         buffer_append(&e->output, buffer_ptr(&msg),
 336             buffer_len(&msg));
 337         buffer_free(&msg);
 338         xfree(data);
 339         xfree(blob);
 340         if (signature != NULL)
 341                 xfree(signature);
 342 }
 343
 344 /* shared */
 345 static void
 346 process_remove_identity(SocketEntry *e, int version)
 347 {
 348         u_int blen, bits;
 349         int success = 0;
 350         Key *key = NULL;
 351         u_char *blob;
 352
 353         switch (version) {
 354         case 1:
 355                 key = key_new(KEY_RSA1);
 356                 bits = buffer_get_int(&e->request);
 357                 buffer_get_bignum(&e->request, key->rsa->e);
 358                 buffer_get_bignum(&e->request, key->rsa->n);
 359
 360                 if (bits != key_size(key))
 361                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 362                             key_size(key), bits);
 363                 break;
 364         case 2:
 365                 blob = buffer_get_string(&e->request, &blen);
 366                 key = key_from_blob(blob, blen);
 367                 xfree(blob);
 368                 break;
 369         }
 370         if (key != NULL) {
 371                 Identity *id = lookup_identity(key, version);
 372                 if (id != NULL) {
 373                         /*
 374                          * We have this key.  Free the old key.  Since we
 375                          * don't want to leave empty slots in the middle of
 376                          * the array, we actually free the key there and move
 377                          * all the entries between the empty slot and the end
 378                          * of the array.
 379                          */
 380                         Idtab *tab = idtab_lookup(version);
 381                         if (tab->nentries < 1)
 382                                 fatal("process_remove_identity: "
 383                                     "internal error: tab->nentries %d",
 384                                     tab->nentries);
 385                         TAILQ_REMOVE(&tab->idlist, id, next);
 386                         free_identity(id);
 387                         tab->nentries--;
 388                         success = 1;
 389                 }
 390                 key_free(key);
 391         }
 392         buffer_put_int(&e->output, 1);
 393         buffer_put_char(&e->output,
 394             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 395 }
 396
 397 static void
 398 process_remove_all_identities(SocketEntry *e, int version)
 399 {
 400         Idtab *tab = idtab_lookup(version);
 401         Identity *id;
 402
 403         /* Loop over all identities and clear the keys. */
 404         for (id = TAILQ_FIRST(&tab->idlist); id;
 405             id = TAILQ_FIRST(&tab->idlist)) {
 406                 TAILQ_REMOVE(&tab->idlist, id, next);
 407                 free_identity(id);
 408         }
 409
 410         /* Mark that there are no identities. */
 411         tab->nentries = 0;
 412
 413         /* Send success. */
 414         buffer_put_int(&e->output, 1);
 415         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 416 }
 417
 418 static void
 419 reaper(void)
 420 {
 421         u_int now = time(NULL);
 422         Identity *id, *nxt;
 423         int version;
 424         Idtab *tab;
 425
 426         for (version = 1; version < 3; version++) {
 427                 tab = idtab_lookup(version);
 428                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 429                         nxt = TAILQ_NEXT(id, next);
 430                         if (id->death != 0 && now >= id->death) {
 431                                 TAILQ_REMOVE(&tab->idlist, id, next);
 432                                 free_identity(id);
 433                                 tab->nentries--;
 434                         }
 435                 }
 436         }
 437 }
 438
 439 static void
 440 process_add_identity(SocketEntry *e, int version)
 441 {
 442         Idtab *tab = idtab_lookup(version);
 443         int type, success = 0, death = 0, confirm = 0;
 444         char *type_name, *comment;
 445         Key *k = NULL;
 446
 447         switch (version) {
 448         case 1:
 449                 k = key_new_private(KEY_RSA1);
 450                 (void) buffer_get_int(&e->request);             /* ignored */
 451                 buffer_get_bignum(&e->request, k->rsa->n);
 452                 buffer_get_bignum(&e->request, k->rsa->e);
 453                 buffer_get_bignum(&e->request, k->rsa->d);
 454                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 455
 456                 /* SSH and SSL have p and q swapped */
 457                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 458                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 459
 460                 /* Generate additional parameters */
 461                 rsa_generate_additional_parameters(k->rsa);
 462                 break;
 463         case 2:
 464                 type_name = buffer_get_string(&e->request, NULL);
 465                 type = key_type_from_name(type_name);
 466                 xfree(type_name);
 467                 switch (type) {
 468                 case KEY_DSA:
 469                         k = key_new_private(type);
 470                         buffer_get_bignum2(&e->request, k->dsa->p);
 471                         buffer_get_bignum2(&e->request, k->dsa->q);
 472                         buffer_get_bignum2(&e->request, k->dsa->g);
 473                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 474                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 475                         break;
 476                 case KEY_RSA:
 477                         k = key_new_private(type);
 478                         buffer_get_bignum2(&e->request, k->rsa->n);
 479                         buffer_get_bignum2(&e->request, k->rsa->e);
 480                         buffer_get_bignum2(&e->request, k->rsa->d);
 481                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 482                         buffer_get_bignum2(&e->request, k->rsa->p);
 483                         buffer_get_bignum2(&e->request, k->rsa->q);
 484
 485                         /* Generate additional parameters */
 486                         rsa_generate_additional_parameters(k->rsa);
 487                         break;
 488                 default:
 489                         buffer_clear(&e->request);
 490                         goto send;
 491                 }
 492                 break;
 493         }
 494         /* enable blinding */
 495         switch (k->type) {
 496         case KEY_RSA:
 497         case KEY_RSA1:
 498                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 499                         error("process_add_identity: RSA_blinding_on failed");
 500                         key_free(k);
 501                         goto send;
 502                 }
 503                 break;
 504         }
 505         comment = buffer_get_string(&e->request, NULL);
 506         if (k == NULL) {
 507                 xfree(comment);
 508                 goto send;
 509         }
 510         success = 1;
 511         while (buffer_len(&e->request)) {
 512                 switch (buffer_get_char(&e->request)) {
 513                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 514                         death = time(NULL) + buffer_get_int(&e->request);
 515                         break;
 516                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 517                         confirm = 1;
 518                         break;
 519                 default:
 520                         break;
 521                 }
 522         }
 523         if (lifetime && !death)
 524                 death = time(NULL) + lifetime;
 525         if (lookup_identity(k, version) == NULL) {
 526                 Identity *id = xmalloc(sizeof(Identity));
 527                 id->key = k;
 528                 id->comment = comment;
 529                 id->death = death;
 530                 id->confirm = confirm;
 531                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 532                 /* Increment the number of identities. */
 533                 tab->nentries++;
 534         } else {
 535                 key_free(k);
 536                 xfree(comment);
 537         }
 538 send:
 539         buffer_put_int(&e->output, 1);
 540         buffer_put_char(&e->output,
 541             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 542 }
 543
 544 /* XXX todo: encrypt sensitive data with passphrase */
 545 static void
 546 process_lock_agent(SocketEntry *e, int lock)
 547 {
 548         int success = 0;
 549         char *passwd;
 550
 551         passwd = buffer_get_string(&e->request, NULL);
 552         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 553                 locked = 0;
 554                 memset(lock_passwd, 0, strlen(lock_passwd));
 555                 xfree(lock_passwd);
 556                 lock_passwd = NULL;
 557                 success = 1;
 558         } else if (!locked && lock) {
 559                 locked = 1;
 560                 lock_passwd = xstrdup(passwd);
 561                 success = 1;
 562         }
 563         memset(passwd, 0, strlen(passwd));
 564         xfree(passwd);
 565
 566         buffer_put_int(&e->output, 1);
 567         buffer_put_char(&e->output,
 568             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 569 }
 570
 571 static void
 572 no_identities(SocketEntry *e, u_int type)
 573 {
 574         Buffer msg;
 575
 576         buffer_init(&msg);
 577         buffer_put_char(&msg,
 578             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 579             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 580         buffer_put_int(&msg, 0);
 581         buffer_put_int(&e->output, buffer_len(&msg));
 582         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 583         buffer_free(&msg);
 584 }
 585
 586 #ifdef SMARTCARD
 587 static void
 588 process_add_smartcard_key (SocketEntry *e)
 589 {
 590         char *sc_reader_id = NULL, *pin;
 591         int i, version, success = 0, death = 0, confirm = 0;
 592         Key **keys, *k;
 593         Identity *id;
 594         Idtab *tab;
 595
 596         sc_reader_id = buffer_get_string(&e->request, NULL);
 597         pin = buffer_get_string(&e->request, NULL);
 598
 599         while (buffer_len(&e->request)) {
 600                 switch (buffer_get_char(&e->request)) {
 601                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 602                         death = time(NULL) + buffer_get_int(&e->request);
 603                         break;
 604                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 605                         confirm = 1;
 606                         break;
 607                 default:
 608                         break;
 609                 }
 610         }
 611         if (lifetime && !death)
 612                 death = time(NULL) + lifetime;
 613
 614         keys = sc_get_keys(sc_reader_id, pin);
 615         xfree(sc_reader_id);
 616         xfree(pin);
 617
 618         if (keys == NULL || keys[0] == NULL) {
 619                 error("sc_get_keys failed");
 620                 goto send;
 621         }
 622         for (i = 0; keys[i] != NULL; i++) {
 623                 k = keys[i];
 624                 version = k->type == KEY_RSA1 ? 1 : 2;
 625                 tab = idtab_lookup(version);
 626                 if (lookup_identity(k, version) == NULL) {
 627                         id = xmalloc(sizeof(Identity));
 628                         id->key = k;
 629                         id->comment = sc_get_key_label(k);
 630                         id->death = death;
 631                         id->confirm = confirm;
 632                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 633                         tab->nentries++;
 634                         success = 1;
 635                 } else {
 636                         key_free(k);
 637                 }
 638                 keys[i] = NULL;
 639         }
 640         xfree(keys);
 641 send:
 642         buffer_put_int(&e->output, 1);
 643         buffer_put_char(&e->output,
 644             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 645 }
 646
 647 static void
 648 process_remove_smartcard_key(SocketEntry *e)
 649 {
 650         char *sc_reader_id = NULL, *pin;
 651         int i, version, success = 0;
 652         Key **keys, *k = NULL;
 653         Identity *id;
 654         Idtab *tab;
 655
 656         sc_reader_id = buffer_get_string(&e->request, NULL);
 657         pin = buffer_get_string(&e->request, NULL);
 658         keys = sc_get_keys(sc_reader_id, pin);
 659         xfree(sc_reader_id);
 660         xfree(pin);
 661
 662         if (keys == NULL || keys[0] == NULL) {
 663                 error("sc_get_keys failed");
 664                 goto send;
 665         }
 666         for (i = 0; keys[i] != NULL; i++) {
 667                 k = keys[i];
 668                 version = k->type == KEY_RSA1 ? 1 : 2;
 669                 if ((id = lookup_identity(k, version)) != NULL) {
 670                         tab = idtab_lookup(version);
 671                         TAILQ_REMOVE(&tab->idlist, id, next);
 672                         tab->nentries--;
 673                         free_identity(id);
 674                         success = 1;
 675                 }
 676                 key_free(k);
 677                 keys[i] = NULL;
 678         }
 679         xfree(keys);
 680 send:
 681         buffer_put_int(&e->output, 1);
 682         buffer_put_char(&e->output,
 683             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 684 }
 685 #endif /* SMARTCARD */
 686
 687 /* dispatch incoming messages */
 688
 689 static void
 690 process_message(SocketEntry *e)
 691 {
 692         u_int msg_len, type;
 693         u_char *cp;
 694
 695         /* kill dead keys */
 696         reaper();
 697
 698         if (buffer_len(&e->input) < 5)
 699                 return;         /* Incomplete message. */
 700         cp = buffer_ptr(&e->input);
 701         msg_len = get_u32(cp);
 702         if (msg_len > 256 * 1024) {
 703                 close_socket(e);
 704                 return;
 705         }
 706         if (buffer_len(&e->input) < msg_len + 4)
 707                 return;
 708
 709         /* move the current input to e->request */
 710         buffer_consume(&e->input, 4);
 711         buffer_clear(&e->request);
 712         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 713         buffer_consume(&e->input, msg_len);
 714         type = buffer_get_char(&e->request);
 715
 716         /* check wheter agent is locked */
 717         if (locked && type != SSH_AGENTC_UNLOCK) {
 718                 buffer_clear(&e->request);
 719                 switch (type) {
 720                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 721                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 722                         /* send empty lists */
 723                         no_identities(e, type);
 724                         break;
 725                 default:
 726                         /* send a fail message for all other request types */
 727                         buffer_put_int(&e->output, 1);
 728                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 729                 }
 730                 return;
 731         }
 732
 733         debug("type %d", type);
 734         switch (type) {
 735         case SSH_AGENTC_LOCK:
 736         case SSH_AGENTC_UNLOCK:
 737                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 738                 break;
 739         /* ssh1 */
 740         case SSH_AGENTC_RSA_CHALLENGE:
 741                 process_authentication_challenge1(e);
 742                 break;
 743         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 744                 process_request_identities(e, 1);
 745                 break;
 746         case SSH_AGENTC_ADD_RSA_IDENTITY:
 747         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 748                 process_add_identity(e, 1);
 749                 break;
 750         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 751                 process_remove_identity(e, 1);
 752                 break;
 753         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 754                 process_remove_all_identities(e, 1);
 755                 break;
 756         /* ssh2 */
 757         case SSH2_AGENTC_SIGN_REQUEST:
 758                 process_sign_request2(e);
 759                 break;
 760         case SSH2_AGENTC_REQUEST_IDENTITIES:
 761                 process_request_identities(e, 2);
 762                 break;
 763         case SSH2_AGENTC_ADD_IDENTITY:
 764         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 765                 process_add_identity(e, 2);
 766                 break;
 767         case SSH2_AGENTC_REMOVE_IDENTITY:
 768                 process_remove_identity(e, 2);
 769                 break;
 770         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 771                 process_remove_all_identities(e, 2);
 772                 break;
 773 #ifdef SMARTCARD
 774         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 775         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 776                 process_add_smartcard_key(e);
 777                 break;
 778         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 779                 process_remove_smartcard_key(e);
 780                 break;
 781 #endif /* SMARTCARD */
 782         default:
 783                 /* Unknown message.  Respond with failure. */
 784                 error("Unknown message %d", type);
 785                 buffer_clear(&e->request);
 786                 buffer_put_int(&e->output, 1);
 787                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 788                 break;
 789         }
 790 }
 791
 792 static void
 793 new_socket(sock_type type, int fd)
 794 {
 795         u_int i, old_alloc, new_alloc;
 796
 797         set_nonblock(fd);
 798
 799         if (fd > max_fd)
 800                 max_fd = fd;
 801
 802         for (i = 0; i < sockets_alloc; i++)
 803                 if (sockets[i].type == AUTH_UNUSED) {
 804                         sockets[i].fd = fd;
 805                         buffer_init(&sockets[i].input);
 806                         buffer_init(&sockets[i].output);
 807                         buffer_init(&sockets[i].request);
 808                         sockets[i].type = type;
 809                         return;
 810                 }
 811         old_alloc = sockets_alloc;
 812         new_alloc = sockets_alloc + 10;
 813         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 814         for (i = old_alloc; i < new_alloc; i++)
 815                 sockets[i].type = AUTH_UNUSED;
 816         sockets_alloc = new_alloc;
 817         sockets[old_alloc].fd = fd;
 818         buffer_init(&sockets[old_alloc].input);
 819         buffer_init(&sockets[old_alloc].output);
 820         buffer_init(&sockets[old_alloc].request);
 821         sockets[old_alloc].type = type;
 822 }
 823
 824 static int
 825 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
 826 {
 827         u_int i, sz;
 828         int n = 0;
 829
 830         for (i = 0; i < sockets_alloc; i++) {
 831                 switch (sockets[i].type) {
 832                 case AUTH_SOCKET:
 833                 case AUTH_CONNECTION:
 834                         n = MAX(n, sockets[i].fd);
 835                         break;
 836                 case AUTH_UNUSED:
 837                         break;
 838                 default:
 839                         fatal("Unknown socket type %d", sockets[i].type);
 840                         break;
 841                 }
 842         }
 843
 844         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 845         if (*fdrp == NULL || sz > *nallocp) {
 846                 if (*fdrp)
 847                         xfree(*fdrp);
 848                 if (*fdwp)
 849                         xfree(*fdwp);
 850                 *fdrp = xmalloc(sz);
 851                 *fdwp = xmalloc(sz);
 852                 *nallocp = sz;
 853         }
 854         if (n < *fdl)
 855                 debug("XXX shrink: %d < %d", n, *fdl);
 856         *fdl = n;
 857         memset(*fdrp, 0, sz);
 858         memset(*fdwp, 0, sz);
 859
 860         for (i = 0; i < sockets_alloc; i++) {
 861                 switch (sockets[i].type) {
 862                 case AUTH_SOCKET:
 863                 case AUTH_CONNECTION:
 864                         FD_SET(sockets[i].fd, *fdrp);
 865                         if (buffer_len(&sockets[i].output) > 0)
 866                                 FD_SET(sockets[i].fd, *fdwp);
 867                         break;
 868                 default:
 869                         break;
 870                 }
 871         }
 872         return (1);
 873 }
 874
 875 static void
 876 after_select(fd_set *readset, fd_set *writeset)
 877 {
 878         struct sockaddr_un sunaddr;
 879         socklen_t slen;
 880         char buf[1024];
 881         int len, sock;
 882         u_int i;
 883         uid_t euid;
 884         gid_t egid;
 885
 886         for (i = 0; i < sockets_alloc; i++)
 887                 switch (sockets[i].type) {
 888                 case AUTH_UNUSED:
 889                         break;
 890                 case AUTH_SOCKET:
 891                         if (FD_ISSET(sockets[i].fd, readset)) {
 892                                 slen = sizeof(sunaddr);
 893                                 sock = accept(sockets[i].fd,
 894                                     (struct sockaddr *)&sunaddr, &slen);
 895                                 if (sock < 0) {
 896                                         error("accept from AUTH_SOCKET: %s",
 897                                             strerror(errno));
 898                                         break;
 899                                 }
 900                                 if (getpeereid(sock, &euid, &egid) < 0) {
 901                                         error("getpeereid %d failed: %s",
 902                                             sock, strerror(errno));
 903                                         close(sock);
 904                                         break;
 905                                 }
 906                                 if ((euid != 0) && (getuid() != euid)) {
 907                                         error("uid mismatch: "
 908                                             "peer euid %u != uid %u",
 909                                             (u_int) euid, (u_int) getuid());
 910                                         close(sock);
 911                                         break;
 912                                 }
 913                                 new_socket(AUTH_CONNECTION, sock);
 914                         }
 915                         break;
 916                 case AUTH_CONNECTION:
 917                         if (buffer_len(&sockets[i].output) > 0 &&
 918                             FD_ISSET(sockets[i].fd, writeset)) {
 919                                 do {
 920                                         len = write(sockets[i].fd,
 921                                             buffer_ptr(&sockets[i].output),
 922                                             buffer_len(&sockets[i].output));
 923                                         if (len == -1 && (errno == EAGAIN ||
 924                                             errno == EINTR))
 925                                                 continue;
 926                                         break;
 927                                 } while (1);
 928                                 if (len <= 0) {
 929                                         close_socket(&sockets[i]);
 930                                         break;
 931                                 }
 932                                 buffer_consume(&sockets[i].output, len);
 933                         }
 934                         if (FD_ISSET(sockets[i].fd, readset)) {
 935                                 do {
 936                                         len = read(sockets[i].fd, buf, sizeof(buf));
 937                                         if (len == -1 && (errno == EAGAIN ||
 938                                             errno == EINTR))
 939                                                 continue;
 940                                         break;
 941                                 } while (1);
 942                                 if (len <= 0) {
 943                                         close_socket(&sockets[i]);
 944                                         break;
 945                                 }
 946                                 buffer_append(&sockets[i].input, buf, len);
 947                                 process_message(&sockets[i]);
 948                         }
 949                         break;
 950                 default:
 951                         fatal("Unknown type %d", sockets[i].type);
 952                 }
 953 }
 954
 955 static void
 956 cleanup_socket(void)
 957 {
 958         if (socket_name[0])
 959                 unlink(socket_name);
 960         if (socket_dir[0])
 961                 rmdir(socket_dir);
 962 }
 963
 964 void
 965 cleanup_exit(int i)
 966 {
 967         cleanup_socket();
 968         _exit(i);
 969 }
 970
 971 /*ARGSUSED*/
 972 static void
 973 cleanup_handler(int sig)
 974 {
 975         cleanup_socket();
 976         _exit(2);
 977 }
 978
 979 /*ARGSUSED*/
 980 static void
 981 check_parent_exists(int sig)
 982 {
 983         int save_errno = errno;
 984
 985         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 986                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 987                 cleanup_handler(sig); /* safe */
 988         }
 989         mysignal(SIGALRM, check_parent_exists);
 990         alarm(10);
 991         errno = save_errno;
 992 }
 993
 994 static void
 995 usage(void)
 996 {
 997         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 998             __progname);
 999         fprintf(stderr, "Options:\n");
1000         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1001         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1002         fprintf(stderr, "  -k          Kill the current agent.\n");
1003         fprintf(stderr, "  -d          Debug mode.\n");
1004         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1005         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1006         exit(1);
1007 }
1008
1009 int
1010 main(int ac, char **av)
1011 {
1012         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1013         int sock, fd,  ch;
1014         u_int nalloc;
1015         char *shell, *format, *pidstr, *agentsocket = NULL;
1016         fd_set *readsetp = NULL, *writesetp = NULL;
1017         struct sockaddr_un sunaddr;
1018 #ifdef HAVE_SETRLIMIT
1019         struct rlimit rlim;
1020 #endif
1021         int prev_mask;
1022         extern int optind;
1023         extern char *optarg;
1024         pid_t pid;
1025         char pidstrbuf[1 + 3 * sizeof pid];
1026
1027         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1028         sanitise_stdfd();
1029
1030         /* drop */
1031         setegid(getgid());
1032         setgid(getgid());
1033
1034 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1035         /* Disable ptrace on Linux without sgid bit */
1036         prctl(PR_SET_DUMPABLE, 0);
1037 #endif
1038
1039         SSLeay_add_all_algorithms();
1040
1041         __progname = ssh_get_progname(av[0]);
1042         init_rng();
1043         seed_rng();
1044
1045         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1046                 switch (ch) {
1047                 case 'c':
1048                         if (s_flag)
1049                                 usage();
1050                         c_flag++;
1051                         break;
1052                 case 'k':
1053                         k_flag++;
1054                         break;
1055                 case 's':
1056                         if (c_flag)
1057                                 usage();
1058                         s_flag++;
1059                         break;
1060                 case 'd':
1061                         if (d_flag)
1062                                 usage();
1063                         d_flag++;
1064                         break;
1065                 case 'a':
1066                         agentsocket = optarg;
1067                         break;
1068                 case 't':
1069                         if ((lifetime = convtime(optarg)) == -1) {
1070                                 fprintf(stderr, "Invalid lifetime\n");
1071                                 usage();
1072                         }
1073                         break;
1074                 default:
1075                         usage();
1076                 }
1077         }
1078         ac -= optind;
1079         av += optind;
1080
1081         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1082                 usage();
1083
1084         if (ac == 0 && !c_flag && !s_flag) {
1085                 shell = getenv("SHELL");
1086                 if (shell != NULL &&
1087                     strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1088                         c_flag = 1;
1089         }
1090         if (k_flag) {
1091                 const char *errstr = NULL;
1092
1093                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1094                 if (pidstr == NULL) {
1095                         fprintf(stderr, "%s not set, cannot kill agent\n",
1096                             SSH_AGENTPID_ENV_NAME);
1097                         exit(1);
1098                 }
1099                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1100                 if (errstr) {
1101                         fprintf(stderr,
1102                             "%s=\"%s\", which is not a good PID: %s\n",
1103                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1104                         exit(1);
1105                 }
1106                 if (kill(pid, SIGTERM) == -1) {
1107                         perror("kill");
1108                         exit(1);
1109                 }
1110                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1111                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1112                 printf(format, SSH_AGENTPID_ENV_NAME);
1113                 printf("echo Agent pid %ld killed;\n", (long)pid);
1114                 exit(0);
1115         }
1116         parent_pid = getpid();
1117
1118         if (agentsocket == NULL) {
1119                 /* Create private directory for agent socket */
1120                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1121                 if (mkdtemp(socket_dir) == NULL) {
1122                         perror("mkdtemp: private socket dir");
1123                         exit(1);
1124                 }
1125                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1126                     (long)parent_pid);
1127         } else {
1128                 /* Try to use specified agent socket */
1129                 socket_dir[0] = '\0';
1130                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1131         }
1132
1133         /*
1134          * Create socket early so it will exist before command gets run from
1135          * the parent.
1136          */
1137         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1138         if (sock < 0) {
1139                 perror("socket");
1140                 *socket_name = '\0'; /* Don't unlink any existing file */
1141                 cleanup_exit(1);
1142         }
1143         memset(&sunaddr, 0, sizeof(sunaddr));
1144         sunaddr.sun_family = AF_UNIX;
1145         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1146         prev_mask = umask(0177);
1147         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1148                 perror("bind");
1149                 *socket_name = '\0'; /* Don't unlink any existing file */
1150                 umask(prev_mask);
1151                 cleanup_exit(1);
1152         }
1153         umask(prev_mask);
1154         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1155                 perror("listen");
1156                 cleanup_exit(1);
1157         }
1158
1159         /*
1160          * Fork, and have the parent execute the command, if any, or present
1161          * the socket data.  The child continues as the authentication agent.
1162          */
1163         if (d_flag) {
1164                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1165                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1166                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1167                     SSH_AUTHSOCKET_ENV_NAME);
1168                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1169                 goto skip;
1170         }
1171         pid = fork();
1172         if (pid == -1) {
1173                 perror("fork");
1174                 cleanup_exit(1);
1175         }
1176         if (pid != 0) {         /* Parent - execute the given command. */
1177                 close(sock);
1178                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1179                 if (ac == 0) {
1180                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1181                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1182                             SSH_AUTHSOCKET_ENV_NAME);
1183                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1184                             SSH_AGENTPID_ENV_NAME);
1185                         printf("echo Agent pid %ld;\n", (long)pid);
1186                         exit(0);
1187                 }
1188                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1189                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1190                         perror("setenv");
1191                         exit(1);
1192                 }
1193                 execvp(av[0], av);
1194                 perror(av[0]);
1195                 exit(1);
1196         }
1197         /* child */
1198         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1199
1200         if (setsid() == -1) {
1201                 error("setsid: %s", strerror(errno));
1202                 cleanup_exit(1);
1203         }
1204
1205         (void)chdir("/");
1206         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1207                 /* XXX might close listen socket */
1208                 (void)dup2(fd, STDIN_FILENO);
1209                 (void)dup2(fd, STDOUT_FILENO);
1210                 (void)dup2(fd, STDERR_FILENO);
1211                 if (fd > 2)
1212                         close(fd);
1213         }
1214
1215 #ifdef HAVE_SETRLIMIT
1216         /* deny core dumps, since memory contains unencrypted private keys */
1217         rlim.rlim_cur = rlim.rlim_max = 0;
1218         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1219                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1220                 cleanup_exit(1);
1221         }
1222 #endif
1223
1224 skip:
1225         new_socket(AUTH_SOCKET, sock);
1226         if (ac > 0) {
1227                 mysignal(SIGALRM, check_parent_exists);
1228                 alarm(10);
1229         }
1230         idtab_init();
1231         if (!d_flag)
1232                 signal(SIGINT, SIG_IGN);
1233         signal(SIGPIPE, SIG_IGN);
1234         signal(SIGHUP, cleanup_handler);
1235         signal(SIGTERM, cleanup_handler);
1236         nalloc = 0;
1237
1238         while (1) {
1239                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1240                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1241                         if (errno == EINTR)
1242                                 continue;
1243                         fatal("select: %s", strerror(errno));
1244                 }
1245                 after_select(readsetp, writesetp);
1246         }
1247         /* NOTREACHED */
1248 }