ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.144 2006/07/17 01:31:10 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 <unistd.h>
  55
  56 #include <openssl/evp.h>
  57 #include <openssl/md5.h>
  58
  59 #include "ssh.h"
  60 #include "rsa.h"
  61 #include "buffer.h"
  62 #include "bufaux.h"
  63 #include "xmalloc.h"
  64 #include "key.h"
  65 #include "authfd.h"
  66 #include "compat.h"
  67 #include "log.h"
  68 #include "misc.h"
  69
  70 #ifdef SMARTCARD
  71 #include "scard.h"
  72 #endif
  73
  74 #if defined(HAVE_SYS_PRCTL_H)
  75 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  76 #endif
  77
  78 typedef enum {
  79         AUTH_UNUSED,
  80         AUTH_SOCKET,
  81         AUTH_CONNECTION
  82 } sock_type;
  83
  84 typedef struct {
  85         int fd;
  86         sock_type type;
  87         Buffer input;
  88         Buffer output;
  89         Buffer request;
  90 } SocketEntry;
  91
  92 u_int sockets_alloc = 0;
  93 SocketEntry *sockets = NULL;
  94
  95 typedef struct identity {
  96         TAILQ_ENTRY(identity) next;
  97         Key *key;
  98         char *comment;
  99         u_int death;
 100         u_int confirm;
 101 } Identity;
 102
 103 typedef struct {
 104         int nentries;
 105         TAILQ_HEAD(idqueue, identity) idlist;
 106 } Idtab;
 107
 108 /* private key table, one per protocol version */
 109 Idtab idtable[3];
 110
 111 int max_fd = 0;
 112
 113 /* pid of shell == parent of agent */
 114 pid_t parent_pid = -1;
 115
 116 /* pathname and directory for AUTH_SOCKET */
 117 char socket_name[MAXPATHLEN];
 118 char socket_dir[MAXPATHLEN];
 119
 120 /* locking */
 121 int locked = 0;
 122 char *lock_passwd = NULL;
 123
 124 extern char *__progname;
 125
 126 /* Default lifetime (0 == forever) */
 127 static int lifetime = 0;
 128
 129 static void
 130 close_socket(SocketEntry *e)
 131 {
 132         close(e->fd);
 133         e->fd = -1;
 134         e->type = AUTH_UNUSED;
 135         buffer_free(&e->input);
 136         buffer_free(&e->output);
 137         buffer_free(&e->request);
 138 }
 139
 140 static void
 141 idtab_init(void)
 142 {
 143         int i;
 144
 145         for (i = 0; i <=2; i++) {
 146                 TAILQ_INIT(&idtable[i].idlist);
 147                 idtable[i].nentries = 0;
 148         }
 149 }
 150
 151 /* return private key table for requested protocol version */
 152 static Idtab *
 153 idtab_lookup(int version)
 154 {
 155         if (version < 1 || version > 2)
 156                 fatal("internal error, bad protocol version %d", version);
 157         return &idtable[version];
 158 }
 159
 160 static void
 161 free_identity(Identity *id)
 162 {
 163         key_free(id->key);
 164         xfree(id->comment);
 165         xfree(id);
 166 }
 167
 168 /* return matching private key for given public key */
 169 static Identity *
 170 lookup_identity(Key *key, int version)
 171 {
 172         Identity *id;
 173
 174         Idtab *tab = idtab_lookup(version);
 175         TAILQ_FOREACH(id, &tab->idlist, next) {
 176                 if (key_equal(key, id->key))
 177                         return (id);
 178         }
 179         return (NULL);
 180 }
 181
 182 /* Check confirmation of keysign request */
 183 static int
 184 confirm_key(Identity *id)
 185 {
 186         char *p;
 187         int ret = -1;
 188
 189         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 190         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 191             id->comment, p))
 192                 ret = 0;
 193         xfree(p);
 194
 195         return (ret);
 196 }
 197
 198 /* send list of supported public keys to 'client' */
 199 static void
 200 process_request_identities(SocketEntry *e, int version)
 201 {
 202         Idtab *tab = idtab_lookup(version);
 203         Identity *id;
 204         Buffer msg;
 205
 206         buffer_init(&msg);
 207         buffer_put_char(&msg, (version == 1) ?
 208             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 209         buffer_put_int(&msg, tab->nentries);
 210         TAILQ_FOREACH(id, &tab->idlist, next) {
 211                 if (id->key->type == KEY_RSA1) {
 212                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 213                         buffer_put_bignum(&msg, id->key->rsa->e);
 214                         buffer_put_bignum(&msg, id->key->rsa->n);
 215                 } else {
 216                         u_char *blob;
 217                         u_int blen;
 218                         key_to_blob(id->key, &blob, &blen);
 219                         buffer_put_string(&msg, blob, blen);
 220                         xfree(blob);
 221                 }
 222                 buffer_put_cstring(&msg, id->comment);
 223         }
 224         buffer_put_int(&e->output, buffer_len(&msg));
 225         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 226         buffer_free(&msg);
 227 }
 228
 229 /* ssh1 only */
 230 static void
 231 process_authentication_challenge1(SocketEntry *e)
 232 {
 233         u_char buf[32], mdbuf[16], session_id[16];
 234         u_int response_type;
 235         BIGNUM *challenge;
 236         Identity *id;
 237         int i, len;
 238         Buffer msg;
 239         MD5_CTX md;
 240         Key *key;
 241
 242         buffer_init(&msg);
 243         key = key_new(KEY_RSA1);
 244         if ((challenge = BN_new()) == NULL)
 245                 fatal("process_authentication_challenge1: BN_new failed");
 246
 247         (void) buffer_get_int(&e->request);                     /* ignored */
 248         buffer_get_bignum(&e->request, key->rsa->e);
 249         buffer_get_bignum(&e->request, key->rsa->n);
 250         buffer_get_bignum(&e->request, challenge);
 251
 252         /* Only protocol 1.1 is supported */
 253         if (buffer_len(&e->request) == 0)
 254                 goto failure;
 255         buffer_get(&e->request, session_id, 16);
 256         response_type = buffer_get_int(&e->request);
 257         if (response_type != 1)
 258                 goto failure;
 259
 260         id = lookup_identity(key, 1);
 261         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 262                 Key *private = id->key;
 263                 /* Decrypt the challenge using the private key. */
 264                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 265                         goto failure;
 266
 267                 /* The response is MD5 of decrypted challenge plus session id. */
 268                 len = BN_num_bytes(challenge);
 269                 if (len <= 0 || len > 32) {
 270                         logit("process_authentication_challenge: bad challenge length %d", len);
 271                         goto failure;
 272                 }
 273                 memset(buf, 0, 32);
 274                 BN_bn2bin(challenge, buf + 32 - len);
 275                 MD5_Init(&md);
 276                 MD5_Update(&md, buf, 32);
 277                 MD5_Update(&md, session_id, 16);
 278                 MD5_Final(mdbuf, &md);
 279
 280                 /* Send the response. */
 281                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 282                 for (i = 0; i < 16; i++)
 283                         buffer_put_char(&msg, mdbuf[i]);
 284                 goto send;
 285         }
 286
 287 failure:
 288         /* Unknown identity or protocol error.  Send failure. */
 289         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 290 send:
 291         buffer_put_int(&e->output, buffer_len(&msg));
 292         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 293         key_free(key);
 294         BN_clear_free(challenge);
 295         buffer_free(&msg);
 296 }
 297
 298 /* ssh2 only */
 299 static void
 300 process_sign_request2(SocketEntry *e)
 301 {
 302         u_char *blob, *data, *signature = NULL;
 303         u_int blen, dlen, slen = 0;
 304         extern int datafellows;
 305         int ok = -1, flags;
 306         Buffer msg;
 307         Key *key;
 308
 309         datafellows = 0;
 310
 311         blob = buffer_get_string(&e->request, &blen);
 312         data = buffer_get_string(&e->request, &dlen);
 313
 314         flags = buffer_get_int(&e->request);
 315         if (flags & SSH_AGENT_OLD_SIGNATURE)
 316                 datafellows = SSH_BUG_SIGBLOB;
 317
 318         key = key_from_blob(blob, blen);
 319         if (key != NULL) {
 320                 Identity *id = lookup_identity(key, 2);
 321                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 322                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 323                 key_free(key);
 324         }
 325         buffer_init(&msg);
 326         if (ok == 0) {
 327                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 328                 buffer_put_string(&msg, signature, slen);
 329         } else {
 330                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 331         }
 332         buffer_put_int(&e->output, buffer_len(&msg));
 333         buffer_append(&e->output, buffer_ptr(&msg),
 334             buffer_len(&msg));
 335         buffer_free(&msg);
 336         xfree(data);
 337         xfree(blob);
 338         if (signature != NULL)
 339                 xfree(signature);
 340 }
 341
 342 /* shared */
 343 static void
 344 process_remove_identity(SocketEntry *e, int version)
 345 {
 346         u_int blen, bits;
 347         int success = 0;
 348         Key *key = NULL;
 349         u_char *blob;
 350
 351         switch (version) {
 352         case 1:
 353                 key = key_new(KEY_RSA1);
 354                 bits = buffer_get_int(&e->request);
 355                 buffer_get_bignum(&e->request, key->rsa->e);
 356                 buffer_get_bignum(&e->request, key->rsa->n);
 357
 358                 if (bits != key_size(key))
 359                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 360                             key_size(key), bits);
 361                 break;
 362         case 2:
 363                 blob = buffer_get_string(&e->request, &blen);
 364                 key = key_from_blob(blob, blen);
 365                 xfree(blob);
 366                 break;
 367         }
 368         if (key != NULL) {
 369                 Identity *id = lookup_identity(key, version);
 370                 if (id != NULL) {
 371                         /*
 372                          * We have this key.  Free the old key.  Since we
 373                          * don't want to leave empty slots in the middle of
 374                          * the array, we actually free the key there and move
 375                          * all the entries between the empty slot and the end
 376                          * of the array.
 377                          */
 378                         Idtab *tab = idtab_lookup(version);
 379                         if (tab->nentries < 1)
 380                                 fatal("process_remove_identity: "
 381                                     "internal error: tab->nentries %d",
 382                                     tab->nentries);
 383                         TAILQ_REMOVE(&tab->idlist, id, next);
 384                         free_identity(id);
 385                         tab->nentries--;
 386                         success = 1;
 387                 }
 388                 key_free(key);
 389         }
 390         buffer_put_int(&e->output, 1);
 391         buffer_put_char(&e->output,
 392             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 393 }
 394
 395 static void
 396 process_remove_all_identities(SocketEntry *e, int version)
 397 {
 398         Idtab *tab = idtab_lookup(version);
 399         Identity *id;
 400
 401         /* Loop over all identities and clear the keys. */
 402         for (id = TAILQ_FIRST(&tab->idlist); id;
 403             id = TAILQ_FIRST(&tab->idlist)) {
 404                 TAILQ_REMOVE(&tab->idlist, id, next);
 405                 free_identity(id);
 406         }
 407
 408         /* Mark that there are no identities. */
 409         tab->nentries = 0;
 410
 411         /* Send success. */
 412         buffer_put_int(&e->output, 1);
 413         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 414 }
 415
 416 static void
 417 reaper(void)
 418 {
 419         u_int now = time(NULL);
 420         Identity *id, *nxt;
 421         int version;
 422         Idtab *tab;
 423
 424         for (version = 1; version < 3; version++) {
 425                 tab = idtab_lookup(version);
 426                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 427                         nxt = TAILQ_NEXT(id, next);
 428                         if (id->death != 0 && now >= id->death) {
 429                                 TAILQ_REMOVE(&tab->idlist, id, next);
 430                                 free_identity(id);
 431                                 tab->nentries--;
 432                         }
 433                 }
 434         }
 435 }
 436
 437 static void
 438 process_add_identity(SocketEntry *e, int version)
 439 {
 440         Idtab *tab = idtab_lookup(version);
 441         int type, success = 0, death = 0, confirm = 0;
 442         char *type_name, *comment;
 443         Key *k = NULL;
 444
 445         switch (version) {
 446         case 1:
 447                 k = key_new_private(KEY_RSA1);
 448                 (void) buffer_get_int(&e->request);             /* ignored */
 449                 buffer_get_bignum(&e->request, k->rsa->n);
 450                 buffer_get_bignum(&e->request, k->rsa->e);
 451                 buffer_get_bignum(&e->request, k->rsa->d);
 452                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 453
 454                 /* SSH and SSL have p and q swapped */
 455                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 456                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 457
 458                 /* Generate additional parameters */
 459                 rsa_generate_additional_parameters(k->rsa);
 460                 break;
 461         case 2:
 462                 type_name = buffer_get_string(&e->request, NULL);
 463                 type = key_type_from_name(type_name);
 464                 xfree(type_name);
 465                 switch (type) {
 466                 case KEY_DSA:
 467                         k = key_new_private(type);
 468                         buffer_get_bignum2(&e->request, k->dsa->p);
 469                         buffer_get_bignum2(&e->request, k->dsa->q);
 470                         buffer_get_bignum2(&e->request, k->dsa->g);
 471                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 472                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 473                         break;
 474                 case KEY_RSA:
 475                         k = key_new_private(type);
 476                         buffer_get_bignum2(&e->request, k->rsa->n);
 477                         buffer_get_bignum2(&e->request, k->rsa->e);
 478                         buffer_get_bignum2(&e->request, k->rsa->d);
 479                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 480                         buffer_get_bignum2(&e->request, k->rsa->p);
 481                         buffer_get_bignum2(&e->request, k->rsa->q);
 482
 483                         /* Generate additional parameters */
 484                         rsa_generate_additional_parameters(k->rsa);
 485                         break;
 486                 default:
 487                         buffer_clear(&e->request);
 488                         goto send;
 489                 }
 490                 break;
 491         }
 492         /* enable blinding */
 493         switch (k->type) {
 494         case KEY_RSA:
 495         case KEY_RSA1:
 496                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 497                         error("process_add_identity: RSA_blinding_on failed");
 498                         key_free(k);
 499                         goto send;
 500                 }
 501                 break;
 502         }
 503         comment = buffer_get_string(&e->request, NULL);
 504         if (k == NULL) {
 505                 xfree(comment);
 506                 goto send;
 507         }
 508         success = 1;
 509         while (buffer_len(&e->request)) {
 510                 switch (buffer_get_char(&e->request)) {
 511                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 512                         death = time(NULL) + buffer_get_int(&e->request);
 513                         break;
 514                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 515                         confirm = 1;
 516                         break;
 517                 default:
 518                         break;
 519                 }
 520         }
 521         if (lifetime && !death)
 522                 death = time(NULL) + lifetime;
 523         if (lookup_identity(k, version) == NULL) {
 524                 Identity *id = xmalloc(sizeof(Identity));
 525                 id->key = k;
 526                 id->comment = comment;
 527                 id->death = death;
 528                 id->confirm = confirm;
 529                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 530                 /* Increment the number of identities. */
 531                 tab->nentries++;
 532         } else {
 533                 key_free(k);
 534                 xfree(comment);
 535         }
 536 send:
 537         buffer_put_int(&e->output, 1);
 538         buffer_put_char(&e->output,
 539             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 540 }
 541
 542 /* XXX todo: encrypt sensitive data with passphrase */
 543 static void
 544 process_lock_agent(SocketEntry *e, int lock)
 545 {
 546         int success = 0;
 547         char *passwd;
 548
 549         passwd = buffer_get_string(&e->request, NULL);
 550         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 551                 locked = 0;
 552                 memset(lock_passwd, 0, strlen(lock_passwd));
 553                 xfree(lock_passwd);
 554                 lock_passwd = NULL;
 555                 success = 1;
 556         } else if (!locked && lock) {
 557                 locked = 1;
 558                 lock_passwd = xstrdup(passwd);
 559                 success = 1;
 560         }
 561         memset(passwd, 0, strlen(passwd));
 562         xfree(passwd);
 563
 564         buffer_put_int(&e->output, 1);
 565         buffer_put_char(&e->output,
 566             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 567 }
 568
 569 static void
 570 no_identities(SocketEntry *e, u_int type)
 571 {
 572         Buffer msg;
 573
 574         buffer_init(&msg);
 575         buffer_put_char(&msg,
 576             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 577             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 578         buffer_put_int(&msg, 0);
 579         buffer_put_int(&e->output, buffer_len(&msg));
 580         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 581         buffer_free(&msg);
 582 }
 583
 584 #ifdef SMARTCARD
 585 static void
 586 process_add_smartcard_key (SocketEntry *e)
 587 {
 588         char *sc_reader_id = NULL, *pin;
 589         int i, version, success = 0, death = 0, confirm = 0;
 590         Key **keys, *k;
 591         Identity *id;
 592         Idtab *tab;
 593
 594         sc_reader_id = buffer_get_string(&e->request, NULL);
 595         pin = buffer_get_string(&e->request, NULL);
 596
 597         while (buffer_len(&e->request)) {
 598                 switch (buffer_get_char(&e->request)) {
 599                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 600                         death = time(NULL) + buffer_get_int(&e->request);
 601                         break;
 602                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 603                         confirm = 1;
 604                         break;
 605                 default:
 606                         break;
 607                 }
 608         }
 609         if (lifetime && !death)
 610                 death = time(NULL) + lifetime;
 611
 612         keys = sc_get_keys(sc_reader_id, pin);
 613         xfree(sc_reader_id);
 614         xfree(pin);
 615
 616         if (keys == NULL || keys[0] == NULL) {
 617                 error("sc_get_keys failed");
 618                 goto send;
 619         }
 620         for (i = 0; keys[i] != NULL; i++) {
 621                 k = keys[i];
 622                 version = k->type == KEY_RSA1 ? 1 : 2;
 623                 tab = idtab_lookup(version);
 624                 if (lookup_identity(k, version) == NULL) {
 625                         id = xmalloc(sizeof(Identity));
 626                         id->key = k;
 627                         id->comment = sc_get_key_label(k);
 628                         id->death = death;
 629                         id->confirm = confirm;
 630                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 631                         tab->nentries++;
 632                         success = 1;
 633                 } else {
 634                         key_free(k);
 635                 }
 636                 keys[i] = NULL;
 637         }
 638         xfree(keys);
 639 send:
 640         buffer_put_int(&e->output, 1);
 641         buffer_put_char(&e->output,
 642             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 643 }
 644
 645 static void
 646 process_remove_smartcard_key(SocketEntry *e)
 647 {
 648         char *sc_reader_id = NULL, *pin;
 649         int i, version, success = 0;
 650         Key **keys, *k = NULL;
 651         Identity *id;
 652         Idtab *tab;
 653
 654         sc_reader_id = buffer_get_string(&e->request, NULL);
 655         pin = buffer_get_string(&e->request, NULL);
 656         keys = sc_get_keys(sc_reader_id, pin);
 657         xfree(sc_reader_id);
 658         xfree(pin);
 659
 660         if (keys == NULL || keys[0] == NULL) {
 661                 error("sc_get_keys failed");
 662                 goto send;
 663         }
 664         for (i = 0; keys[i] != NULL; i++) {
 665                 k = keys[i];
 666                 version = k->type == KEY_RSA1 ? 1 : 2;
 667                 if ((id = lookup_identity(k, version)) != NULL) {
 668                         tab = idtab_lookup(version);
 669                         TAILQ_REMOVE(&tab->idlist, id, next);
 670                         tab->nentries--;
 671                         free_identity(id);
 672                         success = 1;
 673                 }
 674                 key_free(k);
 675                 keys[i] = NULL;
 676         }
 677         xfree(keys);
 678 send:
 679         buffer_put_int(&e->output, 1);
 680         buffer_put_char(&e->output,
 681             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 682 }
 683 #endif /* SMARTCARD */
 684
 685 /* dispatch incoming messages */
 686
 687 static void
 688 process_message(SocketEntry *e)
 689 {
 690         u_int msg_len, type;
 691         u_char *cp;
 692
 693         /* kill dead keys */
 694         reaper();
 695
 696         if (buffer_len(&e->input) < 5)
 697                 return;         /* Incomplete message. */
 698         cp = buffer_ptr(&e->input);
 699         msg_len = get_u32(cp);
 700         if (msg_len > 256 * 1024) {
 701                 close_socket(e);
 702                 return;
 703         }
 704         if (buffer_len(&e->input) < msg_len + 4)
 705                 return;
 706
 707         /* move the current input to e->request */
 708         buffer_consume(&e->input, 4);
 709         buffer_clear(&e->request);
 710         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 711         buffer_consume(&e->input, msg_len);
 712         type = buffer_get_char(&e->request);
 713
 714         /* check wheter agent is locked */
 715         if (locked && type != SSH_AGENTC_UNLOCK) {
 716                 buffer_clear(&e->request);
 717                 switch (type) {
 718                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 719                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 720                         /* send empty lists */
 721                         no_identities(e, type);
 722                         break;
 723                 default:
 724                         /* send a fail message for all other request types */
 725                         buffer_put_int(&e->output, 1);
 726                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 727                 }
 728                 return;
 729         }
 730
 731         debug("type %d", type);
 732         switch (type) {
 733         case SSH_AGENTC_LOCK:
 734         case SSH_AGENTC_UNLOCK:
 735                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 736                 break;
 737         /* ssh1 */
 738         case SSH_AGENTC_RSA_CHALLENGE:
 739                 process_authentication_challenge1(e);
 740                 break;
 741         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 742                 process_request_identities(e, 1);
 743                 break;
 744         case SSH_AGENTC_ADD_RSA_IDENTITY:
 745         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 746                 process_add_identity(e, 1);
 747                 break;
 748         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 749                 process_remove_identity(e, 1);
 750                 break;
 751         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 752                 process_remove_all_identities(e, 1);
 753                 break;
 754         /* ssh2 */
 755         case SSH2_AGENTC_SIGN_REQUEST:
 756                 process_sign_request2(e);
 757                 break;
 758         case SSH2_AGENTC_REQUEST_IDENTITIES:
 759                 process_request_identities(e, 2);
 760                 break;
 761         case SSH2_AGENTC_ADD_IDENTITY:
 762         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 763                 process_add_identity(e, 2);
 764                 break;
 765         case SSH2_AGENTC_REMOVE_IDENTITY:
 766                 process_remove_identity(e, 2);
 767                 break;
 768         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 769                 process_remove_all_identities(e, 2);
 770                 break;
 771 #ifdef SMARTCARD
 772         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 773         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 774                 process_add_smartcard_key(e);
 775                 break;
 776         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 777                 process_remove_smartcard_key(e);
 778                 break;
 779 #endif /* SMARTCARD */
 780         default:
 781                 /* Unknown message.  Respond with failure. */
 782                 error("Unknown message %d", type);
 783                 buffer_clear(&e->request);
 784                 buffer_put_int(&e->output, 1);
 785                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 786                 break;
 787         }
 788 }
 789
 790 static void
 791 new_socket(sock_type type, int fd)
 792 {
 793         u_int i, old_alloc, new_alloc;
 794
 795         set_nonblock(fd);
 796
 797         if (fd > max_fd)
 798                 max_fd = fd;
 799
 800         for (i = 0; i < sockets_alloc; i++)
 801                 if (sockets[i].type == AUTH_UNUSED) {
 802                         sockets[i].fd = fd;
 803                         buffer_init(&sockets[i].input);
 804                         buffer_init(&sockets[i].output);
 805                         buffer_init(&sockets[i].request);
 806                         sockets[i].type = type;
 807                         return;
 808                 }
 809         old_alloc = sockets_alloc;
 810         new_alloc = sockets_alloc + 10;
 811         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 812         for (i = old_alloc; i < new_alloc; i++)
 813                 sockets[i].type = AUTH_UNUSED;
 814         sockets_alloc = new_alloc;
 815         sockets[old_alloc].fd = fd;
 816         buffer_init(&sockets[old_alloc].input);
 817         buffer_init(&sockets[old_alloc].output);
 818         buffer_init(&sockets[old_alloc].request);
 819         sockets[old_alloc].type = type;
 820 }
 821
 822 static int
 823 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
 824 {
 825         u_int i, sz;
 826         int n = 0;
 827
 828         for (i = 0; i < sockets_alloc; i++) {
 829                 switch (sockets[i].type) {
 830                 case AUTH_SOCKET:
 831                 case AUTH_CONNECTION:
 832                         n = MAX(n, sockets[i].fd);
 833                         break;
 834                 case AUTH_UNUSED:
 835                         break;
 836                 default:
 837                         fatal("Unknown socket type %d", sockets[i].type);
 838                         break;
 839                 }
 840         }
 841
 842         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 843         if (*fdrp == NULL || sz > *nallocp) {
 844                 if (*fdrp)
 845                         xfree(*fdrp);
 846                 if (*fdwp)
 847                         xfree(*fdwp);
 848                 *fdrp = xmalloc(sz);
 849                 *fdwp = xmalloc(sz);
 850                 *nallocp = sz;
 851         }
 852         if (n < *fdl)
 853                 debug("XXX shrink: %d < %d", n, *fdl);
 854         *fdl = n;
 855         memset(*fdrp, 0, sz);
 856         memset(*fdwp, 0, sz);
 857
 858         for (i = 0; i < sockets_alloc; i++) {
 859                 switch (sockets[i].type) {
 860                 case AUTH_SOCKET:
 861                 case AUTH_CONNECTION:
 862                         FD_SET(sockets[i].fd, *fdrp);
 863                         if (buffer_len(&sockets[i].output) > 0)
 864                                 FD_SET(sockets[i].fd, *fdwp);
 865                         break;
 866                 default:
 867                         break;
 868                 }
 869         }
 870         return (1);
 871 }
 872
 873 static void
 874 after_select(fd_set *readset, fd_set *writeset)
 875 {
 876         struct sockaddr_un sunaddr;
 877         socklen_t slen;
 878         char buf[1024];
 879         int len, sock;
 880         u_int i;
 881         uid_t euid;
 882         gid_t egid;
 883
 884         for (i = 0; i < sockets_alloc; i++)
 885                 switch (sockets[i].type) {
 886                 case AUTH_UNUSED:
 887                         break;
 888                 case AUTH_SOCKET:
 889                         if (FD_ISSET(sockets[i].fd, readset)) {
 890                                 slen = sizeof(sunaddr);
 891                                 sock = accept(sockets[i].fd,
 892                                     (struct sockaddr *)&sunaddr, &slen);
 893                                 if (sock < 0) {
 894                                         error("accept from AUTH_SOCKET: %s",
 895                                             strerror(errno));
 896                                         break;
 897                                 }
 898                                 if (getpeereid(sock, &euid, &egid) < 0) {
 899                                         error("getpeereid %d failed: %s",
 900                                             sock, strerror(errno));
 901                                         close(sock);
 902                                         break;
 903                                 }
 904                                 if ((euid != 0) && (getuid() != euid)) {
 905                                         error("uid mismatch: "
 906                                             "peer euid %u != uid %u",
 907                                             (u_int) euid, (u_int) getuid());
 908                                         close(sock);
 909                                         break;
 910                                 }
 911                                 new_socket(AUTH_CONNECTION, sock);
 912                         }
 913                         break;
 914                 case AUTH_CONNECTION:
 915                         if (buffer_len(&sockets[i].output) > 0 &&
 916                             FD_ISSET(sockets[i].fd, writeset)) {
 917                                 do {
 918                                         len = write(sockets[i].fd,
 919                                             buffer_ptr(&sockets[i].output),
 920                                             buffer_len(&sockets[i].output));
 921                                         if (len == -1 && (errno == EAGAIN ||
 922                                             errno == EINTR))
 923                                                 continue;
 924                                         break;
 925                                 } while (1);
 926                                 if (len <= 0) {
 927                                         close_socket(&sockets[i]);
 928                                         break;
 929                                 }
 930                                 buffer_consume(&sockets[i].output, len);
 931                         }
 932                         if (FD_ISSET(sockets[i].fd, readset)) {
 933                                 do {
 934                                         len = read(sockets[i].fd, buf, sizeof(buf));
 935                                         if (len == -1 && (errno == EAGAIN ||
 936                                             errno == EINTR))
 937                                                 continue;
 938                                         break;
 939                                 } while (1);
 940                                 if (len <= 0) {
 941                                         close_socket(&sockets[i]);
 942                                         break;
 943                                 }
 944                                 buffer_append(&sockets[i].input, buf, len);
 945                                 process_message(&sockets[i]);
 946                         }
 947                         break;
 948                 default:
 949                         fatal("Unknown type %d", sockets[i].type);
 950                 }
 951 }
 952
 953 static void
 954 cleanup_socket(void)
 955 {
 956         if (socket_name[0])
 957                 unlink(socket_name);
 958         if (socket_dir[0])
 959                 rmdir(socket_dir);
 960 }
 961
 962 void
 963 cleanup_exit(int i)
 964 {
 965         cleanup_socket();
 966         _exit(i);
 967 }
 968
 969 /*ARGSUSED*/
 970 static void
 971 cleanup_handler(int sig)
 972 {
 973         cleanup_socket();
 974         _exit(2);
 975 }
 976
 977 /*ARGSUSED*/
 978 static void
 979 check_parent_exists(int sig)
 980 {
 981         int save_errno = errno;
 982
 983         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 984                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 985                 cleanup_handler(sig); /* safe */
 986         }
 987         mysignal(SIGALRM, check_parent_exists);
 988         alarm(10);
 989         errno = save_errno;
 990 }
 991
 992 static void
 993 usage(void)
 994 {
 995         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 996             __progname);
 997         fprintf(stderr, "Options:\n");
 998         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 999         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1000         fprintf(stderr, "  -k          Kill the current agent.\n");
1001         fprintf(stderr, "  -d          Debug mode.\n");
1002         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1003         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1004         exit(1);
1005 }
1006
1007 int
1008 main(int ac, char **av)
1009 {
1010         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1011         int sock, fd,  ch;
1012         u_int nalloc;
1013         char *shell, *format, *pidstr, *agentsocket = NULL;
1014         fd_set *readsetp = NULL, *writesetp = NULL;
1015         struct sockaddr_un sunaddr;
1016 #ifdef HAVE_SETRLIMIT
1017         struct rlimit rlim;
1018 #endif
1019         int prev_mask;
1020         extern int optind;
1021         extern char *optarg;
1022         pid_t pid;
1023         char pidstrbuf[1 + 3 * sizeof pid];
1024
1025         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1026         sanitise_stdfd();
1027
1028         /* drop */
1029         setegid(getgid());
1030         setgid(getgid());
1031
1032 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1033         /* Disable ptrace on Linux without sgid bit */
1034         prctl(PR_SET_DUMPABLE, 0);
1035 #endif
1036
1037         SSLeay_add_all_algorithms();
1038
1039         __progname = ssh_get_progname(av[0]);
1040         init_rng();
1041         seed_rng();
1042
1043         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1044                 switch (ch) {
1045                 case 'c':
1046                         if (s_flag)
1047                                 usage();
1048                         c_flag++;
1049                         break;
1050                 case 'k':
1051                         k_flag++;
1052                         break;
1053                 case 's':
1054                         if (c_flag)
1055                                 usage();
1056                         s_flag++;
1057                         break;
1058                 case 'd':
1059                         if (d_flag)
1060                                 usage();
1061                         d_flag++;
1062                         break;
1063                 case 'a':
1064                         agentsocket = optarg;
1065                         break;
1066                 case 't':
1067                         if ((lifetime = convtime(optarg)) == -1) {
1068                                 fprintf(stderr, "Invalid lifetime\n");
1069                                 usage();
1070                         }
1071                         break;
1072                 default:
1073                         usage();
1074                 }
1075         }
1076         ac -= optind;
1077         av += optind;
1078
1079         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1080                 usage();
1081
1082         if (ac == 0 && !c_flag && !s_flag) {
1083                 shell = getenv("SHELL");
1084                 if (shell != NULL &&
1085                     strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1086                         c_flag = 1;
1087         }
1088         if (k_flag) {
1089                 const char *errstr = NULL;
1090
1091                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1092                 if (pidstr == NULL) {
1093                         fprintf(stderr, "%s not set, cannot kill agent\n",
1094                             SSH_AGENTPID_ENV_NAME);
1095                         exit(1);
1096                 }
1097                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1098                 if (errstr) {
1099                         fprintf(stderr,
1100                             "%s=\"%s\", which is not a good PID: %s\n",
1101                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1102                         exit(1);
1103                 }
1104                 if (kill(pid, SIGTERM) == -1) {
1105                         perror("kill");
1106                         exit(1);
1107                 }
1108                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1109                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1110                 printf(format, SSH_AGENTPID_ENV_NAME);
1111                 printf("echo Agent pid %ld killed;\n", (long)pid);
1112                 exit(0);
1113         }
1114         parent_pid = getpid();
1115
1116         if (agentsocket == NULL) {
1117                 /* Create private directory for agent socket */
1118                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1119                 if (mkdtemp(socket_dir) == NULL) {
1120                         perror("mkdtemp: private socket dir");
1121                         exit(1);
1122                 }
1123                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1124                     (long)parent_pid);
1125         } else {
1126                 /* Try to use specified agent socket */
1127                 socket_dir[0] = '\0';
1128                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1129         }
1130
1131         /*
1132          * Create socket early so it will exist before command gets run from
1133          * the parent.
1134          */
1135         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1136         if (sock < 0) {
1137                 perror("socket");
1138                 *socket_name = '\0'; /* Don't unlink any existing file */
1139                 cleanup_exit(1);
1140         }
1141         memset(&sunaddr, 0, sizeof(sunaddr));
1142         sunaddr.sun_family = AF_UNIX;
1143         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1144         prev_mask = umask(0177);
1145         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1146                 perror("bind");
1147                 *socket_name = '\0'; /* Don't unlink any existing file */
1148                 umask(prev_mask);
1149                 cleanup_exit(1);
1150         }
1151         umask(prev_mask);
1152         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1153                 perror("listen");
1154                 cleanup_exit(1);
1155         }
1156
1157         /*
1158          * Fork, and have the parent execute the command, if any, or present
1159          * the socket data.  The child continues as the authentication agent.
1160          */
1161         if (d_flag) {
1162                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1163                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1164                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1165                     SSH_AUTHSOCKET_ENV_NAME);
1166                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1167                 goto skip;
1168         }
1169         pid = fork();
1170         if (pid == -1) {
1171                 perror("fork");
1172                 cleanup_exit(1);
1173         }
1174         if (pid != 0) {         /* Parent - execute the given command. */
1175                 close(sock);
1176                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1177                 if (ac == 0) {
1178                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1179                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1180                             SSH_AUTHSOCKET_ENV_NAME);
1181                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1182                             SSH_AGENTPID_ENV_NAME);
1183                         printf("echo Agent pid %ld;\n", (long)pid);
1184                         exit(0);
1185                 }
1186                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1187                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1188                         perror("setenv");
1189                         exit(1);
1190                 }
1191                 execvp(av[0], av);
1192                 perror(av[0]);
1193                 exit(1);
1194         }
1195         /* child */
1196         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1197
1198         if (setsid() == -1) {
1199                 error("setsid: %s", strerror(errno));
1200                 cleanup_exit(1);
1201         }
1202
1203         (void)chdir("/");
1204         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1205                 /* XXX might close listen socket */
1206                 (void)dup2(fd, STDIN_FILENO);
1207                 (void)dup2(fd, STDOUT_FILENO);
1208                 (void)dup2(fd, STDERR_FILENO);
1209                 if (fd > 2)
1210                         close(fd);
1211         }
1212
1213 #ifdef HAVE_SETRLIMIT
1214         /* deny core dumps, since memory contains unencrypted private keys */
1215         rlim.rlim_cur = rlim.rlim_max = 0;
1216         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1217                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1218                 cleanup_exit(1);
1219         }
1220 #endif
1221
1222 skip:
1223         new_socket(AUTH_SOCKET, sock);
1224         if (ac > 0) {
1225                 mysignal(SIGALRM, check_parent_exists);
1226                 alarm(10);
1227         }
1228         idtab_init();
1229         if (!d_flag)
1230                 signal(SIGINT, SIG_IGN);
1231         signal(SIGPIPE, SIG_IGN);
1232         signal(SIGHUP, cleanup_handler);
1233         signal(SIGTERM, cleanup_handler);
1234         nalloc = 0;
1235
1236         while (1) {
1237                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1238                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1239                         if (errno == EINTR)
1240                                 continue;
1241                         fatal("select: %s", strerror(errno));
1242                 }
1243                 after_select(readsetp, writesetp);
1244         }
1245         /* NOTREACHED */
1246 }