ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.147 2006/07/25 02:59:21 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_TIME_H
  43 # include <sys/time.h>
  44 #endif
  45 #ifdef HAVE_SYS_UN_H
  46 # include <sys/un.h>
  47 #endif
  48 #include "openbsd-compat/sys-queue.h"
  49 #include <sys/resource.h>
  50
  51 #include <openssl/evp.h>
  52 #include <openssl/md5.h>
  53
  54 #include <errno.h>
  55 #include <fcntl.h>
  56 #ifdef HAVE_PATHS_H
  57 # include <paths.h>
  58 #endif
  59 #include <signal.h>
  60 #include <time.h>
  61 #include <string.h>
  62 #include <unistd.h>
  63
  64 #include "ssh.h"
  65 #include "rsa.h"
  66 #include "buffer.h"
  67 #include "bufaux.h"
  68 #include "xmalloc.h"
  69 #include "key.h"
  70 #include "authfd.h"
  71 #include "compat.h"
  72 #include "log.h"
  73 #include "misc.h"
  74
  75 #ifdef SMARTCARD
  76 #include "scard.h"
  77 #endif
  78
  79 #if defined(HAVE_SYS_PRCTL_H)
  80 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  81 #endif
  82
  83 typedef enum {
  84         AUTH_UNUSED,
  85         AUTH_SOCKET,
  86         AUTH_CONNECTION
  87 } sock_type;
  88
  89 typedef struct {
  90         int fd;
  91         sock_type type;
  92         Buffer input;
  93         Buffer output;
  94         Buffer request;
  95 } SocketEntry;
  96
  97 u_int sockets_alloc = 0;
  98 SocketEntry *sockets = NULL;
  99
 100 typedef struct identity {
 101         TAILQ_ENTRY(identity) next;
 102         Key *key;
 103         char *comment;
 104         u_int death;
 105         u_int confirm;
 106 } Identity;
 107
 108 typedef struct {
 109         int nentries;
 110         TAILQ_HEAD(idqueue, identity) idlist;
 111 } Idtab;
 112
 113 /* private key table, one per protocol version */
 114 Idtab idtable[3];
 115
 116 int max_fd = 0;
 117
 118 /* pid of shell == parent of agent */
 119 pid_t parent_pid = -1;
 120
 121 /* pathname and directory for AUTH_SOCKET */
 122 char socket_name[MAXPATHLEN];
 123 char socket_dir[MAXPATHLEN];
 124
 125 /* locking */
 126 int locked = 0;
 127 char *lock_passwd = NULL;
 128
 129 extern char *__progname;
 130
 131 /* Default lifetime (0 == forever) */
 132 static int lifetime = 0;
 133
 134 static void
 135 close_socket(SocketEntry *e)
 136 {
 137         close(e->fd);
 138         e->fd = -1;
 139         e->type = AUTH_UNUSED;
 140         buffer_free(&e->input);
 141         buffer_free(&e->output);
 142         buffer_free(&e->request);
 143 }
 144
 145 static void
 146 idtab_init(void)
 147 {
 148         int i;
 149
 150         for (i = 0; i <=2; i++) {
 151                 TAILQ_INIT(&idtable[i].idlist);
 152                 idtable[i].nentries = 0;
 153         }
 154 }
 155
 156 /* return private key table for requested protocol version */
 157 static Idtab *
 158 idtab_lookup(int version)
 159 {
 160         if (version < 1 || version > 2)
 161                 fatal("internal error, bad protocol version %d", version);
 162         return &idtable[version];
 163 }
 164
 165 static void
 166 free_identity(Identity *id)
 167 {
 168         key_free(id->key);
 169         xfree(id->comment);
 170         xfree(id);
 171 }
 172
 173 /* return matching private key for given public key */
 174 static Identity *
 175 lookup_identity(Key *key, int version)
 176 {
 177         Identity *id;
 178
 179         Idtab *tab = idtab_lookup(version);
 180         TAILQ_FOREACH(id, &tab->idlist, next) {
 181                 if (key_equal(key, id->key))
 182                         return (id);
 183         }
 184         return (NULL);
 185 }
 186
 187 /* Check confirmation of keysign request */
 188 static int
 189 confirm_key(Identity *id)
 190 {
 191         char *p;
 192         int ret = -1;
 193
 194         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 195         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 196             id->comment, p))
 197                 ret = 0;
 198         xfree(p);
 199
 200         return (ret);
 201 }
 202
 203 /* send list of supported public keys to 'client' */
 204 static void
 205 process_request_identities(SocketEntry *e, int version)
 206 {
 207         Idtab *tab = idtab_lookup(version);
 208         Identity *id;
 209         Buffer msg;
 210
 211         buffer_init(&msg);
 212         buffer_put_char(&msg, (version == 1) ?
 213             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 214         buffer_put_int(&msg, tab->nentries);
 215         TAILQ_FOREACH(id, &tab->idlist, next) {
 216                 if (id->key->type == KEY_RSA1) {
 217                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 218                         buffer_put_bignum(&msg, id->key->rsa->e);
 219                         buffer_put_bignum(&msg, id->key->rsa->n);
 220                 } else {
 221                         u_char *blob;
 222                         u_int blen;
 223                         key_to_blob(id->key, &blob, &blen);
 224                         buffer_put_string(&msg, blob, blen);
 225                         xfree(blob);
 226                 }
 227                 buffer_put_cstring(&msg, id->comment);
 228         }
 229         buffer_put_int(&e->output, buffer_len(&msg));
 230         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 231         buffer_free(&msg);
 232 }
 233
 234 /* ssh1 only */
 235 static void
 236 process_authentication_challenge1(SocketEntry *e)
 237 {
 238         u_char buf[32], mdbuf[16], session_id[16];
 239         u_int response_type;
 240         BIGNUM *challenge;
 241         Identity *id;
 242         int i, len;
 243         Buffer msg;
 244         MD5_CTX md;
 245         Key *key;
 246
 247         buffer_init(&msg);
 248         key = key_new(KEY_RSA1);
 249         if ((challenge = BN_new()) == NULL)
 250                 fatal("process_authentication_challenge1: BN_new failed");
 251
 252         (void) buffer_get_int(&e->request);                     /* ignored */
 253         buffer_get_bignum(&e->request, key->rsa->e);
 254         buffer_get_bignum(&e->request, key->rsa->n);
 255         buffer_get_bignum(&e->request, challenge);
 256
 257         /* Only protocol 1.1 is supported */
 258         if (buffer_len(&e->request) == 0)
 259                 goto failure;
 260         buffer_get(&e->request, session_id, 16);
 261         response_type = buffer_get_int(&e->request);
 262         if (response_type != 1)
 263                 goto failure;
 264
 265         id = lookup_identity(key, 1);
 266         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 267                 Key *private = id->key;
 268                 /* Decrypt the challenge using the private key. */
 269                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 270                         goto failure;
 271
 272                 /* The response is MD5 of decrypted challenge plus session id. */
 273                 len = BN_num_bytes(challenge);
 274                 if (len <= 0 || len > 32) {
 275                         logit("process_authentication_challenge: bad challenge length %d", len);
 276                         goto failure;
 277                 }
 278                 memset(buf, 0, 32);
 279                 BN_bn2bin(challenge, buf + 32 - len);
 280                 MD5_Init(&md);
 281                 MD5_Update(&md, buf, 32);
 282                 MD5_Update(&md, session_id, 16);
 283                 MD5_Final(mdbuf, &md);
 284
 285                 /* Send the response. */
 286                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 287                 for (i = 0; i < 16; i++)
 288                         buffer_put_char(&msg, mdbuf[i]);
 289                 goto send;
 290         }
 291
 292 failure:
 293         /* Unknown identity or protocol error.  Send failure. */
 294         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 295 send:
 296         buffer_put_int(&e->output, buffer_len(&msg));
 297         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 298         key_free(key);
 299         BN_clear_free(challenge);
 300         buffer_free(&msg);
 301 }
 302
 303 /* ssh2 only */
 304 static void
 305 process_sign_request2(SocketEntry *e)
 306 {
 307         u_char *blob, *data, *signature = NULL;
 308         u_int blen, dlen, slen = 0;
 309         extern int datafellows;
 310         int ok = -1, flags;
 311         Buffer msg;
 312         Key *key;
 313
 314         datafellows = 0;
 315
 316         blob = buffer_get_string(&e->request, &blen);
 317         data = buffer_get_string(&e->request, &dlen);
 318
 319         flags = buffer_get_int(&e->request);
 320         if (flags & SSH_AGENT_OLD_SIGNATURE)
 321                 datafellows = SSH_BUG_SIGBLOB;
 322
 323         key = key_from_blob(blob, blen);
 324         if (key != NULL) {
 325                 Identity *id = lookup_identity(key, 2);
 326                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 327                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 328                 key_free(key);
 329         }
 330         buffer_init(&msg);
 331         if (ok == 0) {
 332                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 333                 buffer_put_string(&msg, signature, slen);
 334         } else {
 335                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 336         }
 337         buffer_put_int(&e->output, buffer_len(&msg));
 338         buffer_append(&e->output, buffer_ptr(&msg),
 339             buffer_len(&msg));
 340         buffer_free(&msg);
 341         xfree(data);
 342         xfree(blob);
 343         if (signature != NULL)
 344                 xfree(signature);
 345 }
 346
 347 /* shared */
 348 static void
 349 process_remove_identity(SocketEntry *e, int version)
 350 {
 351         u_int blen, bits;
 352         int success = 0;
 353         Key *key = NULL;
 354         u_char *blob;
 355
 356         switch (version) {
 357         case 1:
 358                 key = key_new(KEY_RSA1);
 359                 bits = buffer_get_int(&e->request);
 360                 buffer_get_bignum(&e->request, key->rsa->e);
 361                 buffer_get_bignum(&e->request, key->rsa->n);
 362
 363                 if (bits != key_size(key))
 364                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 365                             key_size(key), bits);
 366                 break;
 367         case 2:
 368                 blob = buffer_get_string(&e->request, &blen);
 369                 key = key_from_blob(blob, blen);
 370                 xfree(blob);
 371                 break;
 372         }
 373         if (key != NULL) {
 374                 Identity *id = lookup_identity(key, version);
 375                 if (id != NULL) {
 376                         /*
 377                          * We have this key.  Free the old key.  Since we
 378                          * don't want to leave empty slots in the middle of
 379                          * the array, we actually free the key there and move
 380                          * all the entries between the empty slot and the end
 381                          * of the array.
 382                          */
 383                         Idtab *tab = idtab_lookup(version);
 384                         if (tab->nentries < 1)
 385                                 fatal("process_remove_identity: "
 386                                     "internal error: tab->nentries %d",
 387                                     tab->nentries);
 388                         TAILQ_REMOVE(&tab->idlist, id, next);
 389                         free_identity(id);
 390                         tab->nentries--;
 391                         success = 1;
 392                 }
 393                 key_free(key);
 394         }
 395         buffer_put_int(&e->output, 1);
 396         buffer_put_char(&e->output,
 397             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 398 }
 399
 400 static void
 401 process_remove_all_identities(SocketEntry *e, int version)
 402 {
 403         Idtab *tab = idtab_lookup(version);
 404         Identity *id;
 405
 406         /* Loop over all identities and clear the keys. */
 407         for (id = TAILQ_FIRST(&tab->idlist); id;
 408             id = TAILQ_FIRST(&tab->idlist)) {
 409                 TAILQ_REMOVE(&tab->idlist, id, next);
 410                 free_identity(id);
 411         }
 412
 413         /* Mark that there are no identities. */
 414         tab->nentries = 0;
 415
 416         /* Send success. */
 417         buffer_put_int(&e->output, 1);
 418         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 419 }
 420
 421 static void
 422 reaper(void)
 423 {
 424         u_int now = time(NULL);
 425         Identity *id, *nxt;
 426         int version;
 427         Idtab *tab;
 428
 429         for (version = 1; version < 3; version++) {
 430                 tab = idtab_lookup(version);
 431                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 432                         nxt = TAILQ_NEXT(id, next);
 433                         if (id->death != 0 && now >= id->death) {
 434                                 TAILQ_REMOVE(&tab->idlist, id, next);
 435                                 free_identity(id);
 436                                 tab->nentries--;
 437                         }
 438                 }
 439         }
 440 }
 441
 442 static void
 443 process_add_identity(SocketEntry *e, int version)
 444 {
 445         Idtab *tab = idtab_lookup(version);
 446         int type, success = 0, death = 0, confirm = 0;
 447         char *type_name, *comment;
 448         Key *k = NULL;
 449
 450         switch (version) {
 451         case 1:
 452                 k = key_new_private(KEY_RSA1);
 453                 (void) buffer_get_int(&e->request);             /* ignored */
 454                 buffer_get_bignum(&e->request, k->rsa->n);
 455                 buffer_get_bignum(&e->request, k->rsa->e);
 456                 buffer_get_bignum(&e->request, k->rsa->d);
 457                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 458
 459                 /* SSH and SSL have p and q swapped */
 460                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 461                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 462
 463                 /* Generate additional parameters */
 464                 rsa_generate_additional_parameters(k->rsa);
 465                 break;
 466         case 2:
 467                 type_name = buffer_get_string(&e->request, NULL);
 468                 type = key_type_from_name(type_name);
 469                 xfree(type_name);
 470                 switch (type) {
 471                 case KEY_DSA:
 472                         k = key_new_private(type);
 473                         buffer_get_bignum2(&e->request, k->dsa->p);
 474                         buffer_get_bignum2(&e->request, k->dsa->q);
 475                         buffer_get_bignum2(&e->request, k->dsa->g);
 476                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 477                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 478                         break;
 479                 case KEY_RSA:
 480                         k = key_new_private(type);
 481                         buffer_get_bignum2(&e->request, k->rsa->n);
 482                         buffer_get_bignum2(&e->request, k->rsa->e);
 483                         buffer_get_bignum2(&e->request, k->rsa->d);
 484                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 485                         buffer_get_bignum2(&e->request, k->rsa->p);
 486                         buffer_get_bignum2(&e->request, k->rsa->q);
 487
 488                         /* Generate additional parameters */
 489                         rsa_generate_additional_parameters(k->rsa);
 490                         break;
 491                 default:
 492                         buffer_clear(&e->request);
 493                         goto send;
 494                 }
 495                 break;
 496         }
 497         /* enable blinding */
 498         switch (k->type) {
 499         case KEY_RSA:
 500         case KEY_RSA1:
 501                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 502                         error("process_add_identity: RSA_blinding_on failed");
 503                         key_free(k);
 504                         goto send;
 505                 }
 506                 break;
 507         }
 508         comment = buffer_get_string(&e->request, NULL);
 509         if (k == NULL) {
 510                 xfree(comment);
 511                 goto send;
 512         }
 513         success = 1;
 514         while (buffer_len(&e->request)) {
 515                 switch (buffer_get_char(&e->request)) {
 516                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 517                         death = time(NULL) + buffer_get_int(&e->request);
 518                         break;
 519                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 520                         confirm = 1;
 521                         break;
 522                 default:
 523                         break;
 524                 }
 525         }
 526         if (lifetime && !death)
 527                 death = time(NULL) + lifetime;
 528         if (lookup_identity(k, version) == NULL) {
 529                 Identity *id = xmalloc(sizeof(Identity));
 530                 id->key = k;
 531                 id->comment = comment;
 532                 id->death = death;
 533                 id->confirm = confirm;
 534                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 535                 /* Increment the number of identities. */
 536                 tab->nentries++;
 537         } else {
 538                 key_free(k);
 539                 xfree(comment);
 540         }
 541 send:
 542         buffer_put_int(&e->output, 1);
 543         buffer_put_char(&e->output,
 544             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 545 }
 546
 547 /* XXX todo: encrypt sensitive data with passphrase */
 548 static void
 549 process_lock_agent(SocketEntry *e, int lock)
 550 {
 551         int success = 0;
 552         char *passwd;
 553
 554         passwd = buffer_get_string(&e->request, NULL);
 555         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 556                 locked = 0;
 557                 memset(lock_passwd, 0, strlen(lock_passwd));
 558                 xfree(lock_passwd);
 559                 lock_passwd = NULL;
 560                 success = 1;
 561         } else if (!locked && lock) {
 562                 locked = 1;
 563                 lock_passwd = xstrdup(passwd);
 564                 success = 1;
 565         }
 566         memset(passwd, 0, strlen(passwd));
 567         xfree(passwd);
 568
 569         buffer_put_int(&e->output, 1);
 570         buffer_put_char(&e->output,
 571             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 572 }
 573
 574 static void
 575 no_identities(SocketEntry *e, u_int type)
 576 {
 577         Buffer msg;
 578
 579         buffer_init(&msg);
 580         buffer_put_char(&msg,
 581             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 582             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 583         buffer_put_int(&msg, 0);
 584         buffer_put_int(&e->output, buffer_len(&msg));
 585         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 586         buffer_free(&msg);
 587 }
 588
 589 #ifdef SMARTCARD
 590 static void
 591 process_add_smartcard_key (SocketEntry *e)
 592 {
 593         char *sc_reader_id = NULL, *pin;
 594         int i, version, success = 0, death = 0, confirm = 0;
 595         Key **keys, *k;
 596         Identity *id;
 597         Idtab *tab;
 598
 599         sc_reader_id = buffer_get_string(&e->request, NULL);
 600         pin = buffer_get_string(&e->request, NULL);
 601
 602         while (buffer_len(&e->request)) {
 603                 switch (buffer_get_char(&e->request)) {
 604                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 605                         death = time(NULL) + buffer_get_int(&e->request);
 606                         break;
 607                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 608                         confirm = 1;
 609                         break;
 610                 default:
 611                         break;
 612                 }
 613         }
 614         if (lifetime && !death)
 615                 death = time(NULL) + lifetime;
 616
 617         keys = sc_get_keys(sc_reader_id, pin);
 618         xfree(sc_reader_id);
 619         xfree(pin);
 620
 621         if (keys == NULL || keys[0] == NULL) {
 622                 error("sc_get_keys failed");
 623                 goto send;
 624         }
 625         for (i = 0; keys[i] != NULL; i++) {
 626                 k = keys[i];
 627                 version = k->type == KEY_RSA1 ? 1 : 2;
 628                 tab = idtab_lookup(version);
 629                 if (lookup_identity(k, version) == NULL) {
 630                         id = xmalloc(sizeof(Identity));
 631                         id->key = k;
 632                         id->comment = sc_get_key_label(k);
 633                         id->death = death;
 634                         id->confirm = confirm;
 635                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 636                         tab->nentries++;
 637                         success = 1;
 638                 } else {
 639                         key_free(k);
 640                 }
 641                 keys[i] = NULL;
 642         }
 643         xfree(keys);
 644 send:
 645         buffer_put_int(&e->output, 1);
 646         buffer_put_char(&e->output,
 647             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 648 }
 649
 650 static void
 651 process_remove_smartcard_key(SocketEntry *e)
 652 {
 653         char *sc_reader_id = NULL, *pin;
 654         int i, version, success = 0;
 655         Key **keys, *k = NULL;
 656         Identity *id;
 657         Idtab *tab;
 658
 659         sc_reader_id = buffer_get_string(&e->request, NULL);
 660         pin = buffer_get_string(&e->request, NULL);
 661         keys = sc_get_keys(sc_reader_id, pin);
 662         xfree(sc_reader_id);
 663         xfree(pin);
 664
 665         if (keys == NULL || keys[0] == NULL) {
 666                 error("sc_get_keys failed");
 667                 goto send;
 668         }
 669         for (i = 0; keys[i] != NULL; i++) {
 670                 k = keys[i];
 671                 version = k->type == KEY_RSA1 ? 1 : 2;
 672                 if ((id = lookup_identity(k, version)) != NULL) {
 673                         tab = idtab_lookup(version);
 674                         TAILQ_REMOVE(&tab->idlist, id, next);
 675                         tab->nentries--;
 676                         free_identity(id);
 677                         success = 1;
 678                 }
 679                 key_free(k);
 680                 keys[i] = NULL;
 681         }
 682         xfree(keys);
 683 send:
 684         buffer_put_int(&e->output, 1);
 685         buffer_put_char(&e->output,
 686             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 687 }
 688 #endif /* SMARTCARD */
 689
 690 /* dispatch incoming messages */
 691
 692 static void
 693 process_message(SocketEntry *e)
 694 {
 695         u_int msg_len, type;
 696         u_char *cp;
 697
 698         /* kill dead keys */
 699         reaper();
 700
 701         if (buffer_len(&e->input) < 5)
 702                 return;         /* Incomplete message. */
 703         cp = buffer_ptr(&e->input);
 704         msg_len = get_u32(cp);
 705         if (msg_len > 256 * 1024) {
 706                 close_socket(e);
 707                 return;
 708         }
 709         if (buffer_len(&e->input) < msg_len + 4)
 710                 return;
 711
 712         /* move the current input to e->request */
 713         buffer_consume(&e->input, 4);
 714         buffer_clear(&e->request);
 715         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 716         buffer_consume(&e->input, msg_len);
 717         type = buffer_get_char(&e->request);
 718
 719         /* check wheter agent is locked */
 720         if (locked && type != SSH_AGENTC_UNLOCK) {
 721                 buffer_clear(&e->request);
 722                 switch (type) {
 723                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 724                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 725                         /* send empty lists */
 726                         no_identities(e, type);
 727                         break;
 728                 default:
 729                         /* send a fail message for all other request types */
 730                         buffer_put_int(&e->output, 1);
 731                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 732                 }
 733                 return;
 734         }
 735
 736         debug("type %d", type);
 737         switch (type) {
 738         case SSH_AGENTC_LOCK:
 739         case SSH_AGENTC_UNLOCK:
 740                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 741                 break;
 742         /* ssh1 */
 743         case SSH_AGENTC_RSA_CHALLENGE:
 744                 process_authentication_challenge1(e);
 745                 break;
 746         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 747                 process_request_identities(e, 1);
 748                 break;
 749         case SSH_AGENTC_ADD_RSA_IDENTITY:
 750         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 751                 process_add_identity(e, 1);
 752                 break;
 753         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 754                 process_remove_identity(e, 1);
 755                 break;
 756         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 757                 process_remove_all_identities(e, 1);
 758                 break;
 759         /* ssh2 */
 760         case SSH2_AGENTC_SIGN_REQUEST:
 761                 process_sign_request2(e);
 762                 break;
 763         case SSH2_AGENTC_REQUEST_IDENTITIES:
 764                 process_request_identities(e, 2);
 765                 break;
 766         case SSH2_AGENTC_ADD_IDENTITY:
 767         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 768                 process_add_identity(e, 2);
 769                 break;
 770         case SSH2_AGENTC_REMOVE_IDENTITY:
 771                 process_remove_identity(e, 2);
 772                 break;
 773         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 774                 process_remove_all_identities(e, 2);
 775                 break;
 776 #ifdef SMARTCARD
 777         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 778         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 779                 process_add_smartcard_key(e);
 780                 break;
 781         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 782                 process_remove_smartcard_key(e);
 783                 break;
 784 #endif /* SMARTCARD */
 785         default:
 786                 /* Unknown message.  Respond with failure. */
 787                 error("Unknown message %d", type);
 788                 buffer_clear(&e->request);
 789                 buffer_put_int(&e->output, 1);
 790                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 791                 break;
 792         }
 793 }
 794
 795 static void
 796 new_socket(sock_type type, int fd)
 797 {
 798         u_int i, old_alloc, new_alloc;
 799
 800         set_nonblock(fd);
 801
 802         if (fd > max_fd)
 803                 max_fd = fd;
 804
 805         for (i = 0; i < sockets_alloc; i++)
 806                 if (sockets[i].type == AUTH_UNUSED) {
 807                         sockets[i].fd = fd;
 808                         buffer_init(&sockets[i].input);
 809                         buffer_init(&sockets[i].output);
 810                         buffer_init(&sockets[i].request);
 811                         sockets[i].type = type;
 812                         return;
 813                 }
 814         old_alloc = sockets_alloc;
 815         new_alloc = sockets_alloc + 10;
 816         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 817         for (i = old_alloc; i < new_alloc; i++)
 818                 sockets[i].type = AUTH_UNUSED;
 819         sockets_alloc = new_alloc;
 820         sockets[old_alloc].fd = fd;
 821         buffer_init(&sockets[old_alloc].input);
 822         buffer_init(&sockets[old_alloc].output);
 823         buffer_init(&sockets[old_alloc].request);
 824         sockets[old_alloc].type = type;
 825 }
 826
 827 static int
 828 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
 829 {
 830         u_int i, sz;
 831         int n = 0;
 832
 833         for (i = 0; i < sockets_alloc; i++) {
 834                 switch (sockets[i].type) {
 835                 case AUTH_SOCKET:
 836                 case AUTH_CONNECTION:
 837                         n = MAX(n, sockets[i].fd);
 838                         break;
 839                 case AUTH_UNUSED:
 840                         break;
 841                 default:
 842                         fatal("Unknown socket type %d", sockets[i].type);
 843                         break;
 844                 }
 845         }
 846
 847         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 848         if (*fdrp == NULL || sz > *nallocp) {
 849                 if (*fdrp)
 850                         xfree(*fdrp);
 851                 if (*fdwp)
 852                         xfree(*fdwp);
 853                 *fdrp = xmalloc(sz);
 854                 *fdwp = xmalloc(sz);
 855                 *nallocp = sz;
 856         }
 857         if (n < *fdl)
 858                 debug("XXX shrink: %d < %d", n, *fdl);
 859         *fdl = n;
 860         memset(*fdrp, 0, sz);
 861         memset(*fdwp, 0, sz);
 862
 863         for (i = 0; i < sockets_alloc; i++) {
 864                 switch (sockets[i].type) {
 865                 case AUTH_SOCKET:
 866                 case AUTH_CONNECTION:
 867                         FD_SET(sockets[i].fd, *fdrp);
 868                         if (buffer_len(&sockets[i].output) > 0)
 869                                 FD_SET(sockets[i].fd, *fdwp);
 870                         break;
 871                 default:
 872                         break;
 873                 }
 874         }
 875         return (1);
 876 }
 877
 878 static void
 879 after_select(fd_set *readset, fd_set *writeset)
 880 {
 881         struct sockaddr_un sunaddr;
 882         socklen_t slen;
 883         char buf[1024];
 884         int len, sock;
 885         u_int i;
 886         uid_t euid;
 887         gid_t egid;
 888
 889         for (i = 0; i < sockets_alloc; i++)
 890                 switch (sockets[i].type) {
 891                 case AUTH_UNUSED:
 892                         break;
 893                 case AUTH_SOCKET:
 894                         if (FD_ISSET(sockets[i].fd, readset)) {
 895                                 slen = sizeof(sunaddr);
 896                                 sock = accept(sockets[i].fd,
 897                                     (struct sockaddr *)&sunaddr, &slen);
 898                                 if (sock < 0) {
 899                                         error("accept from AUTH_SOCKET: %s",
 900                                             strerror(errno));
 901                                         break;
 902                                 }
 903                                 if (getpeereid(sock, &euid, &egid) < 0) {
 904                                         error("getpeereid %d failed: %s",
 905                                             sock, strerror(errno));
 906                                         close(sock);
 907                                         break;
 908                                 }
 909                                 if ((euid != 0) && (getuid() != euid)) {
 910                                         error("uid mismatch: "
 911                                             "peer euid %u != uid %u",
 912                                             (u_int) euid, (u_int) getuid());
 913                                         close(sock);
 914                                         break;
 915                                 }
 916                                 new_socket(AUTH_CONNECTION, sock);
 917                         }
 918                         break;
 919                 case AUTH_CONNECTION:
 920                         if (buffer_len(&sockets[i].output) > 0 &&
 921                             FD_ISSET(sockets[i].fd, writeset)) {
 922                                 do {
 923                                         len = write(sockets[i].fd,
 924                                             buffer_ptr(&sockets[i].output),
 925                                             buffer_len(&sockets[i].output));
 926                                         if (len == -1 && (errno == EAGAIN ||
 927                                             errno == EINTR))
 928                                                 continue;
 929                                         break;
 930                                 } while (1);
 931                                 if (len <= 0) {
 932                                         close_socket(&sockets[i]);
 933                                         break;
 934                                 }
 935                                 buffer_consume(&sockets[i].output, len);
 936                         }
 937                         if (FD_ISSET(sockets[i].fd, readset)) {
 938                                 do {
 939                                         len = read(sockets[i].fd, buf, sizeof(buf));
 940                                         if (len == -1 && (errno == EAGAIN ||
 941                                             errno == EINTR))
 942                                                 continue;
 943                                         break;
 944                                 } while (1);
 945                                 if (len <= 0) {
 946                                         close_socket(&sockets[i]);
 947                                         break;
 948                                 }
 949                                 buffer_append(&sockets[i].input, buf, len);
 950                                 process_message(&sockets[i]);
 951                         }
 952                         break;
 953                 default:
 954                         fatal("Unknown type %d", sockets[i].type);
 955                 }
 956 }
 957
 958 static void
 959 cleanup_socket(void)
 960 {
 961         if (socket_name[0])
 962                 unlink(socket_name);
 963         if (socket_dir[0])
 964                 rmdir(socket_dir);
 965 }
 966
 967 void
 968 cleanup_exit(int i)
 969 {
 970         cleanup_socket();
 971         _exit(i);
 972 }
 973
 974 /*ARGSUSED*/
 975 static void
 976 cleanup_handler(int sig)
 977 {
 978         cleanup_socket();
 979         _exit(2);
 980 }
 981
 982 /*ARGSUSED*/
 983 static void
 984 check_parent_exists(int sig)
 985 {
 986         int save_errno = errno;
 987
 988         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 989                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 990                 cleanup_handler(sig); /* safe */
 991         }
 992         mysignal(SIGALRM, check_parent_exists);
 993         alarm(10);
 994         errno = save_errno;
 995 }
 996
 997 static void
 998 usage(void)
 999 {
1000         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
1001             __progname);
1002         fprintf(stderr, "Options:\n");
1003         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1004         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1005         fprintf(stderr, "  -k          Kill the current agent.\n");
1006         fprintf(stderr, "  -d          Debug mode.\n");
1007         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1008         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1009         exit(1);
1010 }
1011
1012 int
1013 main(int ac, char **av)
1014 {
1015         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1016         int sock, fd,  ch;
1017         u_int nalloc;
1018         char *shell, *format, *pidstr, *agentsocket = NULL;
1019         fd_set *readsetp = NULL, *writesetp = NULL;
1020         struct sockaddr_un sunaddr;
1021 #ifdef HAVE_SETRLIMIT
1022         struct rlimit rlim;
1023 #endif
1024         int prev_mask;
1025         extern int optind;
1026         extern char *optarg;
1027         pid_t pid;
1028         char pidstrbuf[1 + 3 * sizeof pid];
1029
1030         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1031         sanitise_stdfd();
1032
1033         /* drop */
1034         setegid(getgid());
1035         setgid(getgid());
1036
1037 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1038         /* Disable ptrace on Linux without sgid bit */
1039         prctl(PR_SET_DUMPABLE, 0);
1040 #endif
1041
1042         SSLeay_add_all_algorithms();
1043
1044         __progname = ssh_get_progname(av[0]);
1045         init_rng();
1046         seed_rng();
1047
1048         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1049                 switch (ch) {
1050                 case 'c':
1051                         if (s_flag)
1052                                 usage();
1053                         c_flag++;
1054                         break;
1055                 case 'k':
1056                         k_flag++;
1057                         break;
1058                 case 's':
1059                         if (c_flag)
1060                                 usage();
1061                         s_flag++;
1062                         break;
1063                 case 'd':
1064                         if (d_flag)
1065                                 usage();
1066                         d_flag++;
1067                         break;
1068                 case 'a':
1069                         agentsocket = optarg;
1070                         break;
1071                 case 't':
1072                         if ((lifetime = convtime(optarg)) == -1) {
1073                                 fprintf(stderr, "Invalid lifetime\n");
1074                                 usage();
1075                         }
1076                         break;
1077                 default:
1078                         usage();
1079                 }
1080         }
1081         ac -= optind;
1082         av += optind;
1083
1084         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1085                 usage();
1086
1087         if (ac == 0 && !c_flag && !s_flag) {
1088                 shell = getenv("SHELL");
1089                 if (shell != NULL &&
1090                     strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1091                         c_flag = 1;
1092         }
1093         if (k_flag) {
1094                 const char *errstr = NULL;
1095
1096                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1097                 if (pidstr == NULL) {
1098                         fprintf(stderr, "%s not set, cannot kill agent\n",
1099                             SSH_AGENTPID_ENV_NAME);
1100                         exit(1);
1101                 }
1102                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1103                 if (errstr) {
1104                         fprintf(stderr,
1105                             "%s=\"%s\", which is not a good PID: %s\n",
1106                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1107                         exit(1);
1108                 }
1109                 if (kill(pid, SIGTERM) == -1) {
1110                         perror("kill");
1111                         exit(1);
1112                 }
1113                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1114                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1115                 printf(format, SSH_AGENTPID_ENV_NAME);
1116                 printf("echo Agent pid %ld killed;\n", (long)pid);
1117                 exit(0);
1118         }
1119         parent_pid = getpid();
1120
1121         if (agentsocket == NULL) {
1122                 /* Create private directory for agent socket */
1123                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1124                 if (mkdtemp(socket_dir) == NULL) {
1125                         perror("mkdtemp: private socket dir");
1126                         exit(1);
1127                 }
1128                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1129                     (long)parent_pid);
1130         } else {
1131                 /* Try to use specified agent socket */
1132                 socket_dir[0] = '\0';
1133                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1134         }
1135
1136         /*
1137          * Create socket early so it will exist before command gets run from
1138          * the parent.
1139          */
1140         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1141         if (sock < 0) {
1142                 perror("socket");
1143                 *socket_name = '\0'; /* Don't unlink any existing file */
1144                 cleanup_exit(1);
1145         }
1146         memset(&sunaddr, 0, sizeof(sunaddr));
1147         sunaddr.sun_family = AF_UNIX;
1148         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1149         prev_mask = umask(0177);
1150         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1151                 perror("bind");
1152                 *socket_name = '\0'; /* Don't unlink any existing file */
1153                 umask(prev_mask);
1154                 cleanup_exit(1);
1155         }
1156         umask(prev_mask);
1157         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1158                 perror("listen");
1159                 cleanup_exit(1);
1160         }
1161
1162         /*
1163          * Fork, and have the parent execute the command, if any, or present
1164          * the socket data.  The child continues as the authentication agent.
1165          */
1166         if (d_flag) {
1167                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1168                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1169                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1170                     SSH_AUTHSOCKET_ENV_NAME);
1171                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1172                 goto skip;
1173         }
1174         pid = fork();
1175         if (pid == -1) {
1176                 perror("fork");
1177                 cleanup_exit(1);
1178         }
1179         if (pid != 0) {         /* Parent - execute the given command. */
1180                 close(sock);
1181                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1182                 if (ac == 0) {
1183                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1184                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1185                             SSH_AUTHSOCKET_ENV_NAME);
1186                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1187                             SSH_AGENTPID_ENV_NAME);
1188                         printf("echo Agent pid %ld;\n", (long)pid);
1189                         exit(0);
1190                 }
1191                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1192                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1193                         perror("setenv");
1194                         exit(1);
1195                 }
1196                 execvp(av[0], av);
1197                 perror(av[0]);
1198                 exit(1);
1199         }
1200         /* child */
1201         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1202
1203         if (setsid() == -1) {
1204                 error("setsid: %s", strerror(errno));
1205                 cleanup_exit(1);
1206         }
1207
1208         (void)chdir("/");
1209         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1210                 /* XXX might close listen socket */
1211                 (void)dup2(fd, STDIN_FILENO);
1212                 (void)dup2(fd, STDOUT_FILENO);
1213                 (void)dup2(fd, STDERR_FILENO);
1214                 if (fd > 2)
1215                         close(fd);
1216         }
1217
1218 #ifdef HAVE_SETRLIMIT
1219         /* deny core dumps, since memory contains unencrypted private keys */
1220         rlim.rlim_cur = rlim.rlim_max = 0;
1221         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1222                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1223                 cleanup_exit(1);
1224         }
1225 #endif
1226
1227 skip:
1228         new_socket(AUTH_SOCKET, sock);
1229         if (ac > 0) {
1230                 mysignal(SIGALRM, check_parent_exists);
1231                 alarm(10);
1232         }
1233         idtab_init();
1234         if (!d_flag)
1235                 signal(SIGINT, SIG_IGN);
1236         signal(SIGPIPE, SIG_IGN);
1237         signal(SIGHUP, cleanup_handler);
1238         signal(SIGTERM, cleanup_handler);
1239         nalloc = 0;
1240
1241         while (1) {
1242                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1243                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1244                         if (errno == EINTR)
1245                                 continue;
1246                         fatal("select: %s", strerror(errno));
1247                 }
1248                 after_select(readsetp, writesetp);
1249         }
1250         /* NOTREACHED */
1251 }