ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.149 2006/07/26 13:57:17 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/param.h>
  41 #include <sys/resource.h>
  42 #include <sys/stat.h>
  43 #include <sys/socket.h>
  44 #ifdef HAVE_SYS_TIME_H
  45 # include <sys/time.h>
  46 #endif
  47 #ifdef HAVE_SYS_UN_H
  48 # include <sys/un.h>
  49 #endif
  50 #include "openbsd-compat/sys-queue.h"
  51
  52 #include <openssl/evp.h>
  53 #include <openssl/md5.h>
  54
  55 #include <errno.h>
  56 #include <fcntl.h>
  57 #ifdef HAVE_PATHS_H
  58 # include <paths.h>
  59 #endif
  60 #include <signal.h>
  61 #include <stdlib.h>
  62 #include <time.h>
  63 #include <string.h>
  64 #include <unistd.h>
  65
  66 #include "ssh.h"
  67 #include "rsa.h"
  68 #include "buffer.h"
  69 #include "bufaux.h"
  70 #include "xmalloc.h"
  71 #include "key.h"
  72 #include "authfd.h"
  73 #include "compat.h"
  74 #include "log.h"
  75 #include "misc.h"
  76
  77 #ifdef SMARTCARD
  78 #include "scard.h"
  79 #endif
  80
  81 #if defined(HAVE_SYS_PRCTL_H)
  82 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  83 #endif
  84
  85 typedef enum {
  86         AUTH_UNUSED,
  87         AUTH_SOCKET,
  88         AUTH_CONNECTION
  89 } sock_type;
  90
  91 typedef struct {
  92         int fd;
  93         sock_type type;
  94         Buffer input;
  95         Buffer output;
  96         Buffer request;
  97 } SocketEntry;
  98
  99 u_int sockets_alloc = 0;
 100 SocketEntry *sockets = NULL;
 101
 102 typedef struct identity {
 103         TAILQ_ENTRY(identity) next;
 104         Key *key;
 105         char *comment;
 106         u_int death;
 107         u_int confirm;
 108 } Identity;
 109
 110 typedef struct {
 111         int nentries;
 112         TAILQ_HEAD(idqueue, identity) idlist;
 113 } Idtab;
 114
 115 /* private key table, one per protocol version */
 116 Idtab idtable[3];
 117
 118 int max_fd = 0;
 119
 120 /* pid of shell == parent of agent */
 121 pid_t parent_pid = -1;
 122
 123 /* pathname and directory for AUTH_SOCKET */
 124 char socket_name[MAXPATHLEN];
 125 char socket_dir[MAXPATHLEN];
 126
 127 /* locking */
 128 int locked = 0;
 129 char *lock_passwd = NULL;
 130
 131 extern char *__progname;
 132
 133 /* Default lifetime (0 == forever) */
 134 static int lifetime = 0;
 135
 136 static void
 137 close_socket(SocketEntry *e)
 138 {
 139         close(e->fd);
 140         e->fd = -1;
 141         e->type = AUTH_UNUSED;
 142         buffer_free(&e->input);
 143         buffer_free(&e->output);
 144         buffer_free(&e->request);
 145 }
 146
 147 static void
 148 idtab_init(void)
 149 {
 150         int i;
 151
 152         for (i = 0; i <=2; i++) {
 153                 TAILQ_INIT(&idtable[i].idlist);
 154                 idtable[i].nentries = 0;
 155         }
 156 }
 157
 158 /* return private key table for requested protocol version */
 159 static Idtab *
 160 idtab_lookup(int version)
 161 {
 162         if (version < 1 || version > 2)
 163                 fatal("internal error, bad protocol version %d", version);
 164         return &idtable[version];
 165 }
 166
 167 static void
 168 free_identity(Identity *id)
 169 {
 170         key_free(id->key);
 171         xfree(id->comment);
 172         xfree(id);
 173 }
 174
 175 /* return matching private key for given public key */
 176 static Identity *
 177 lookup_identity(Key *key, int version)
 178 {
 179         Identity *id;
 180
 181         Idtab *tab = idtab_lookup(version);
 182         TAILQ_FOREACH(id, &tab->idlist, next) {
 183                 if (key_equal(key, id->key))
 184                         return (id);
 185         }
 186         return (NULL);
 187 }
 188
 189 /* Check confirmation of keysign request */
 190 static int
 191 confirm_key(Identity *id)
 192 {
 193         char *p;
 194         int ret = -1;
 195
 196         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 197         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 198             id->comment, p))
 199                 ret = 0;
 200         xfree(p);
 201
 202         return (ret);
 203 }
 204
 205 /* send list of supported public keys to 'client' */
 206 static void
 207 process_request_identities(SocketEntry *e, int version)
 208 {
 209         Idtab *tab = idtab_lookup(version);
 210         Identity *id;
 211         Buffer msg;
 212
 213         buffer_init(&msg);
 214         buffer_put_char(&msg, (version == 1) ?
 215             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 216         buffer_put_int(&msg, tab->nentries);
 217         TAILQ_FOREACH(id, &tab->idlist, next) {
 218                 if (id->key->type == KEY_RSA1) {
 219                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 220                         buffer_put_bignum(&msg, id->key->rsa->e);
 221                         buffer_put_bignum(&msg, id->key->rsa->n);
 222                 } else {
 223                         u_char *blob;
 224                         u_int blen;
 225                         key_to_blob(id->key, &blob, &blen);
 226                         buffer_put_string(&msg, blob, blen);
 227                         xfree(blob);
 228                 }
 229                 buffer_put_cstring(&msg, id->comment);
 230         }
 231         buffer_put_int(&e->output, buffer_len(&msg));
 232         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 233         buffer_free(&msg);
 234 }
 235
 236 /* ssh1 only */
 237 static void
 238 process_authentication_challenge1(SocketEntry *e)
 239 {
 240         u_char buf[32], mdbuf[16], session_id[16];
 241         u_int response_type;
 242         BIGNUM *challenge;
 243         Identity *id;
 244         int i, len;
 245         Buffer msg;
 246         MD5_CTX md;
 247         Key *key;
 248
 249         buffer_init(&msg);
 250         key = key_new(KEY_RSA1);
 251         if ((challenge = BN_new()) == NULL)
 252                 fatal("process_authentication_challenge1: BN_new failed");
 253
 254         (void) buffer_get_int(&e->request);                     /* ignored */
 255         buffer_get_bignum(&e->request, key->rsa->e);
 256         buffer_get_bignum(&e->request, key->rsa->n);
 257         buffer_get_bignum(&e->request, challenge);
 258
 259         /* Only protocol 1.1 is supported */
 260         if (buffer_len(&e->request) == 0)
 261                 goto failure;
 262         buffer_get(&e->request, session_id, 16);
 263         response_type = buffer_get_int(&e->request);
 264         if (response_type != 1)
 265                 goto failure;
 266
 267         id = lookup_identity(key, 1);
 268         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 269                 Key *private = id->key;
 270                 /* Decrypt the challenge using the private key. */
 271                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 272                         goto failure;
 273
 274                 /* The response is MD5 of decrypted challenge plus session id. */
 275                 len = BN_num_bytes(challenge);
 276                 if (len <= 0 || len > 32) {
 277                         logit("process_authentication_challenge: bad challenge length %d", len);
 278                         goto failure;
 279                 }
 280                 memset(buf, 0, 32);
 281                 BN_bn2bin(challenge, buf + 32 - len);
 282                 MD5_Init(&md);
 283                 MD5_Update(&md, buf, 32);
 284                 MD5_Update(&md, session_id, 16);
 285                 MD5_Final(mdbuf, &md);
 286
 287                 /* Send the response. */
 288                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 289                 for (i = 0; i < 16; i++)
 290                         buffer_put_char(&msg, mdbuf[i]);
 291                 goto send;
 292         }
 293
 294 failure:
 295         /* Unknown identity or protocol error.  Send failure. */
 296         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 297 send:
 298         buffer_put_int(&e->output, buffer_len(&msg));
 299         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 300         key_free(key);
 301         BN_clear_free(challenge);
 302         buffer_free(&msg);
 303 }
 304
 305 /* ssh2 only */
 306 static void
 307 process_sign_request2(SocketEntry *e)
 308 {
 309         u_char *blob, *data, *signature = NULL;
 310         u_int blen, dlen, slen = 0;
 311         extern int datafellows;
 312         int ok = -1, flags;
 313         Buffer msg;
 314         Key *key;
 315
 316         datafellows = 0;
 317
 318         blob = buffer_get_string(&e->request, &blen);
 319         data = buffer_get_string(&e->request, &dlen);
 320
 321         flags = buffer_get_int(&e->request);
 322         if (flags & SSH_AGENT_OLD_SIGNATURE)
 323                 datafellows = SSH_BUG_SIGBLOB;
 324
 325         key = key_from_blob(blob, blen);
 326         if (key != NULL) {
 327                 Identity *id = lookup_identity(key, 2);
 328                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 329                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 330                 key_free(key);
 331         }
 332         buffer_init(&msg);
 333         if (ok == 0) {
 334                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 335                 buffer_put_string(&msg, signature, slen);
 336         } else {
 337                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 338         }
 339         buffer_put_int(&e->output, buffer_len(&msg));
 340         buffer_append(&e->output, buffer_ptr(&msg),
 341             buffer_len(&msg));
 342         buffer_free(&msg);
 343         xfree(data);
 344         xfree(blob);
 345         if (signature != NULL)
 346                 xfree(signature);
 347 }
 348
 349 /* shared */
 350 static void
 351 process_remove_identity(SocketEntry *e, int version)
 352 {
 353         u_int blen, bits;
 354         int success = 0;
 355         Key *key = NULL;
 356         u_char *blob;
 357
 358         switch (version) {
 359         case 1:
 360                 key = key_new(KEY_RSA1);
 361                 bits = buffer_get_int(&e->request);
 362                 buffer_get_bignum(&e->request, key->rsa->e);
 363                 buffer_get_bignum(&e->request, key->rsa->n);
 364
 365                 if (bits != key_size(key))
 366                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 367                             key_size(key), bits);
 368                 break;
 369         case 2:
 370                 blob = buffer_get_string(&e->request, &blen);
 371                 key = key_from_blob(blob, blen);
 372                 xfree(blob);
 373                 break;
 374         }
 375         if (key != NULL) {
 376                 Identity *id = lookup_identity(key, version);
 377                 if (id != NULL) {
 378                         /*
 379                          * We have this key.  Free the old key.  Since we
 380                          * don't want to leave empty slots in the middle of
 381                          * the array, we actually free the key there and move
 382                          * all the entries between the empty slot and the end
 383                          * of the array.
 384                          */
 385                         Idtab *tab = idtab_lookup(version);
 386                         if (tab->nentries < 1)
 387                                 fatal("process_remove_identity: "
 388                                     "internal error: tab->nentries %d",
 389                                     tab->nentries);
 390                         TAILQ_REMOVE(&tab->idlist, id, next);
 391                         free_identity(id);
 392                         tab->nentries--;
 393                         success = 1;
 394                 }
 395                 key_free(key);
 396         }
 397         buffer_put_int(&e->output, 1);
 398         buffer_put_char(&e->output,
 399             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 400 }
 401
 402 static void
 403 process_remove_all_identities(SocketEntry *e, int version)
 404 {
 405         Idtab *tab = idtab_lookup(version);
 406         Identity *id;
 407
 408         /* Loop over all identities and clear the keys. */
 409         for (id = TAILQ_FIRST(&tab->idlist); id;
 410             id = TAILQ_FIRST(&tab->idlist)) {
 411                 TAILQ_REMOVE(&tab->idlist, id, next);
 412                 free_identity(id);
 413         }
 414
 415         /* Mark that there are no identities. */
 416         tab->nentries = 0;
 417
 418         /* Send success. */
 419         buffer_put_int(&e->output, 1);
 420         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 421 }
 422
 423 static void
 424 reaper(void)
 425 {
 426         u_int now = time(NULL);
 427         Identity *id, *nxt;
 428         int version;
 429         Idtab *tab;
 430
 431         for (version = 1; version < 3; version++) {
 432                 tab = idtab_lookup(version);
 433                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 434                         nxt = TAILQ_NEXT(id, next);
 435                         if (id->death != 0 && now >= id->death) {
 436                                 TAILQ_REMOVE(&tab->idlist, id, next);
 437                                 free_identity(id);
 438                                 tab->nentries--;
 439                         }
 440                 }
 441         }
 442 }
 443
 444 static void
 445 process_add_identity(SocketEntry *e, int version)
 446 {
 447         Idtab *tab = idtab_lookup(version);
 448         int type, success = 0, death = 0, confirm = 0;
 449         char *type_name, *comment;
 450         Key *k = NULL;
 451
 452         switch (version) {
 453         case 1:
 454                 k = key_new_private(KEY_RSA1);
 455                 (void) buffer_get_int(&e->request);             /* ignored */
 456                 buffer_get_bignum(&e->request, k->rsa->n);
 457                 buffer_get_bignum(&e->request, k->rsa->e);
 458                 buffer_get_bignum(&e->request, k->rsa->d);
 459                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 460
 461                 /* SSH and SSL have p and q swapped */
 462                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 463                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 464
 465                 /* Generate additional parameters */
 466                 rsa_generate_additional_parameters(k->rsa);
 467                 break;
 468         case 2:
 469                 type_name = buffer_get_string(&e->request, NULL);
 470                 type = key_type_from_name(type_name);
 471                 xfree(type_name);
 472                 switch (type) {
 473                 case KEY_DSA:
 474                         k = key_new_private(type);
 475                         buffer_get_bignum2(&e->request, k->dsa->p);
 476                         buffer_get_bignum2(&e->request, k->dsa->q);
 477                         buffer_get_bignum2(&e->request, k->dsa->g);
 478                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 479                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 480                         break;
 481                 case KEY_RSA:
 482                         k = key_new_private(type);
 483                         buffer_get_bignum2(&e->request, k->rsa->n);
 484                         buffer_get_bignum2(&e->request, k->rsa->e);
 485                         buffer_get_bignum2(&e->request, k->rsa->d);
 486                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 487                         buffer_get_bignum2(&e->request, k->rsa->p);
 488                         buffer_get_bignum2(&e->request, k->rsa->q);
 489
 490                         /* Generate additional parameters */
 491                         rsa_generate_additional_parameters(k->rsa);
 492                         break;
 493                 default:
 494                         buffer_clear(&e->request);
 495                         goto send;
 496                 }
 497                 break;
 498         }
 499         /* enable blinding */
 500         switch (k->type) {
 501         case KEY_RSA:
 502         case KEY_RSA1:
 503                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 504                         error("process_add_identity: RSA_blinding_on failed");
 505                         key_free(k);
 506                         goto send;
 507                 }
 508                 break;
 509         }
 510         comment = buffer_get_string(&e->request, NULL);
 511         if (k == NULL) {
 512                 xfree(comment);
 513                 goto send;
 514         }
 515         success = 1;
 516         while (buffer_len(&e->request)) {
 517                 switch (buffer_get_char(&e->request)) {
 518                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 519                         death = time(NULL) + buffer_get_int(&e->request);
 520                         break;
 521                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 522                         confirm = 1;
 523                         break;
 524                 default:
 525                         break;
 526                 }
 527         }
 528         if (lifetime && !death)
 529                 death = time(NULL) + lifetime;
 530         if (lookup_identity(k, version) == NULL) {
 531                 Identity *id = xmalloc(sizeof(Identity));
 532                 id->key = k;
 533                 id->comment = comment;
 534                 id->death = death;
 535                 id->confirm = confirm;
 536                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 537                 /* Increment the number of identities. */
 538                 tab->nentries++;
 539         } else {
 540                 key_free(k);
 541                 xfree(comment);
 542         }
 543 send:
 544         buffer_put_int(&e->output, 1);
 545         buffer_put_char(&e->output,
 546             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 547 }
 548
 549 /* XXX todo: encrypt sensitive data with passphrase */
 550 static void
 551 process_lock_agent(SocketEntry *e, int lock)
 552 {
 553         int success = 0;
 554         char *passwd;
 555
 556         passwd = buffer_get_string(&e->request, NULL);
 557         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 558                 locked = 0;
 559                 memset(lock_passwd, 0, strlen(lock_passwd));
 560                 xfree(lock_passwd);
 561                 lock_passwd = NULL;
 562                 success = 1;
 563         } else if (!locked && lock) {
 564                 locked = 1;
 565                 lock_passwd = xstrdup(passwd);
 566                 success = 1;
 567         }
 568         memset(passwd, 0, strlen(passwd));
 569         xfree(passwd);
 570
 571         buffer_put_int(&e->output, 1);
 572         buffer_put_char(&e->output,
 573             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 574 }
 575
 576 static void
 577 no_identities(SocketEntry *e, u_int type)
 578 {
 579         Buffer msg;
 580
 581         buffer_init(&msg);
 582         buffer_put_char(&msg,
 583             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 584             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 585         buffer_put_int(&msg, 0);
 586         buffer_put_int(&e->output, buffer_len(&msg));
 587         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 588         buffer_free(&msg);
 589 }
 590
 591 #ifdef SMARTCARD
 592 static void
 593 process_add_smartcard_key (SocketEntry *e)
 594 {
 595         char *sc_reader_id = NULL, *pin;
 596         int i, version, success = 0, death = 0, confirm = 0;
 597         Key **keys, *k;
 598         Identity *id;
 599         Idtab *tab;
 600
 601         sc_reader_id = buffer_get_string(&e->request, NULL);
 602         pin = buffer_get_string(&e->request, NULL);
 603
 604         while (buffer_len(&e->request)) {
 605                 switch (buffer_get_char(&e->request)) {
 606                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 607                         death = time(NULL) + buffer_get_int(&e->request);
 608                         break;
 609                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 610                         confirm = 1;
 611                         break;
 612                 default:
 613                         break;
 614                 }
 615         }
 616         if (lifetime && !death)
 617                 death = time(NULL) + lifetime;
 618
 619         keys = sc_get_keys(sc_reader_id, pin);
 620         xfree(sc_reader_id);
 621         xfree(pin);
 622
 623         if (keys == NULL || keys[0] == NULL) {
 624                 error("sc_get_keys failed");
 625                 goto send;
 626         }
 627         for (i = 0; keys[i] != NULL; i++) {
 628                 k = keys[i];
 629                 version = k->type == KEY_RSA1 ? 1 : 2;
 630                 tab = idtab_lookup(version);
 631                 if (lookup_identity(k, version) == NULL) {
 632                         id = xmalloc(sizeof(Identity));
 633                         id->key = k;
 634                         id->comment = sc_get_key_label(k);
 635                         id->death = death;
 636                         id->confirm = confirm;
 637                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 638                         tab->nentries++;
 639                         success = 1;
 640                 } else {
 641                         key_free(k);
 642                 }
 643                 keys[i] = NULL;
 644         }
 645         xfree(keys);
 646 send:
 647         buffer_put_int(&e->output, 1);
 648         buffer_put_char(&e->output,
 649             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 650 }
 651
 652 static void
 653 process_remove_smartcard_key(SocketEntry *e)
 654 {
 655         char *sc_reader_id = NULL, *pin;
 656         int i, version, success = 0;
 657         Key **keys, *k = NULL;
 658         Identity *id;
 659         Idtab *tab;
 660
 661         sc_reader_id = buffer_get_string(&e->request, NULL);
 662         pin = buffer_get_string(&e->request, NULL);
 663         keys = sc_get_keys(sc_reader_id, pin);
 664         xfree(sc_reader_id);
 665         xfree(pin);
 666
 667         if (keys == NULL || keys[0] == NULL) {
 668                 error("sc_get_keys failed");
 669                 goto send;
 670         }
 671         for (i = 0; keys[i] != NULL; i++) {
 672                 k = keys[i];
 673                 version = k->type == KEY_RSA1 ? 1 : 2;
 674                 if ((id = lookup_identity(k, version)) != NULL) {
 675                         tab = idtab_lookup(version);
 676                         TAILQ_REMOVE(&tab->idlist, id, next);
 677                         tab->nentries--;
 678                         free_identity(id);
 679                         success = 1;
 680                 }
 681                 key_free(k);
 682                 keys[i] = NULL;
 683         }
 684         xfree(keys);
 685 send:
 686         buffer_put_int(&e->output, 1);
 687         buffer_put_char(&e->output,
 688             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 689 }
 690 #endif /* SMARTCARD */
 691
 692 /* dispatch incoming messages */
 693
 694 static void
 695 process_message(SocketEntry *e)
 696 {
 697         u_int msg_len, type;
 698         u_char *cp;
 699
 700         /* kill dead keys */
 701         reaper();
 702
 703         if (buffer_len(&e->input) < 5)
 704                 return;         /* Incomplete message. */
 705         cp = buffer_ptr(&e->input);
 706         msg_len = get_u32(cp);
 707         if (msg_len > 256 * 1024) {
 708                 close_socket(e);
 709                 return;
 710         }
 711         if (buffer_len(&e->input) < msg_len + 4)
 712                 return;
 713
 714         /* move the current input to e->request */
 715         buffer_consume(&e->input, 4);
 716         buffer_clear(&e->request);
 717         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 718         buffer_consume(&e->input, msg_len);
 719         type = buffer_get_char(&e->request);
 720
 721         /* check wheter agent is locked */
 722         if (locked && type != SSH_AGENTC_UNLOCK) {
 723                 buffer_clear(&e->request);
 724                 switch (type) {
 725                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 726                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 727                         /* send empty lists */
 728                         no_identities(e, type);
 729                         break;
 730                 default:
 731                         /* send a fail message for all other request types */
 732                         buffer_put_int(&e->output, 1);
 733                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 734                 }
 735                 return;
 736         }
 737
 738         debug("type %d", type);
 739         switch (type) {
 740         case SSH_AGENTC_LOCK:
 741         case SSH_AGENTC_UNLOCK:
 742                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 743                 break;
 744         /* ssh1 */
 745         case SSH_AGENTC_RSA_CHALLENGE:
 746                 process_authentication_challenge1(e);
 747                 break;
 748         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 749                 process_request_identities(e, 1);
 750                 break;
 751         case SSH_AGENTC_ADD_RSA_IDENTITY:
 752         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 753                 process_add_identity(e, 1);
 754                 break;
 755         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 756                 process_remove_identity(e, 1);
 757                 break;
 758         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 759                 process_remove_all_identities(e, 1);
 760                 break;
 761         /* ssh2 */
 762         case SSH2_AGENTC_SIGN_REQUEST:
 763                 process_sign_request2(e);
 764                 break;
 765         case SSH2_AGENTC_REQUEST_IDENTITIES:
 766                 process_request_identities(e, 2);
 767                 break;
 768         case SSH2_AGENTC_ADD_IDENTITY:
 769         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 770                 process_add_identity(e, 2);
 771                 break;
 772         case SSH2_AGENTC_REMOVE_IDENTITY:
 773                 process_remove_identity(e, 2);
 774                 break;
 775         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 776                 process_remove_all_identities(e, 2);
 777                 break;
 778 #ifdef SMARTCARD
 779         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 780         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 781                 process_add_smartcard_key(e);
 782                 break;
 783         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 784                 process_remove_smartcard_key(e);
 785                 break;
 786 #endif /* SMARTCARD */
 787         default:
 788                 /* Unknown message.  Respond with failure. */
 789                 error("Unknown message %d", type);
 790                 buffer_clear(&e->request);
 791                 buffer_put_int(&e->output, 1);
 792                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 793                 break;
 794         }
 795 }
 796
 797 static void
 798 new_socket(sock_type type, int fd)
 799 {
 800         u_int i, old_alloc, new_alloc;
 801
 802         set_nonblock(fd);
 803
 804         if (fd > max_fd)
 805                 max_fd = fd;
 806
 807         for (i = 0; i < sockets_alloc; i++)
 808                 if (sockets[i].type == AUTH_UNUSED) {
 809                         sockets[i].fd = fd;
 810                         buffer_init(&sockets[i].input);
 811                         buffer_init(&sockets[i].output);
 812                         buffer_init(&sockets[i].request);
 813                         sockets[i].type = type;
 814                         return;
 815                 }
 816         old_alloc = sockets_alloc;
 817         new_alloc = sockets_alloc + 10;
 818         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 819         for (i = old_alloc; i < new_alloc; i++)
 820                 sockets[i].type = AUTH_UNUSED;
 821         sockets_alloc = new_alloc;
 822         sockets[old_alloc].fd = fd;
 823         buffer_init(&sockets[old_alloc].input);
 824         buffer_init(&sockets[old_alloc].output);
 825         buffer_init(&sockets[old_alloc].request);
 826         sockets[old_alloc].type = type;
 827 }
 828
 829 static int
 830 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
 831 {
 832         u_int i, sz;
 833         int n = 0;
 834
 835         for (i = 0; i < sockets_alloc; i++) {
 836                 switch (sockets[i].type) {
 837                 case AUTH_SOCKET:
 838                 case AUTH_CONNECTION:
 839                         n = MAX(n, sockets[i].fd);
 840                         break;
 841                 case AUTH_UNUSED:
 842                         break;
 843                 default:
 844                         fatal("Unknown socket type %d", sockets[i].type);
 845                         break;
 846                 }
 847         }
 848
 849         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 850         if (*fdrp == NULL || sz > *nallocp) {
 851                 if (*fdrp)
 852                         xfree(*fdrp);
 853                 if (*fdwp)
 854                         xfree(*fdwp);
 855                 *fdrp = xmalloc(sz);
 856                 *fdwp = xmalloc(sz);
 857                 *nallocp = sz;
 858         }
 859         if (n < *fdl)
 860                 debug("XXX shrink: %d < %d", n, *fdl);
 861         *fdl = n;
 862         memset(*fdrp, 0, sz);
 863         memset(*fdwp, 0, sz);
 864
 865         for (i = 0; i < sockets_alloc; i++) {
 866                 switch (sockets[i].type) {
 867                 case AUTH_SOCKET:
 868                 case AUTH_CONNECTION:
 869                         FD_SET(sockets[i].fd, *fdrp);
 870                         if (buffer_len(&sockets[i].output) > 0)
 871                                 FD_SET(sockets[i].fd, *fdwp);
 872                         break;
 873                 default:
 874                         break;
 875                 }
 876         }
 877         return (1);
 878 }
 879
 880 static void
 881 after_select(fd_set *readset, fd_set *writeset)
 882 {
 883         struct sockaddr_un sunaddr;
 884         socklen_t slen;
 885         char buf[1024];
 886         int len, sock;
 887         u_int i;
 888         uid_t euid;
 889         gid_t egid;
 890
 891         for (i = 0; i < sockets_alloc; i++)
 892                 switch (sockets[i].type) {
 893                 case AUTH_UNUSED:
 894                         break;
 895                 case AUTH_SOCKET:
 896                         if (FD_ISSET(sockets[i].fd, readset)) {
 897                                 slen = sizeof(sunaddr);
 898                                 sock = accept(sockets[i].fd,
 899                                     (struct sockaddr *)&sunaddr, &slen);
 900                                 if (sock < 0) {
 901                                         error("accept from AUTH_SOCKET: %s",
 902                                             strerror(errno));
 903                                         break;
 904                                 }
 905                                 if (getpeereid(sock, &euid, &egid) < 0) {
 906                                         error("getpeereid %d failed: %s",
 907                                             sock, strerror(errno));
 908                                         close(sock);
 909                                         break;
 910                                 }
 911                                 if ((euid != 0) && (getuid() != euid)) {
 912                                         error("uid mismatch: "
 913                                             "peer euid %u != uid %u",
 914                                             (u_int) euid, (u_int) getuid());
 915                                         close(sock);
 916                                         break;
 917                                 }
 918                                 new_socket(AUTH_CONNECTION, sock);
 919                         }
 920                         break;
 921                 case AUTH_CONNECTION:
 922                         if (buffer_len(&sockets[i].output) > 0 &&
 923                             FD_ISSET(sockets[i].fd, writeset)) {
 924                                 do {
 925                                         len = write(sockets[i].fd,
 926                                             buffer_ptr(&sockets[i].output),
 927                                             buffer_len(&sockets[i].output));
 928                                         if (len == -1 && (errno == EAGAIN ||
 929                                             errno == EINTR))
 930                                                 continue;
 931                                         break;
 932                                 } while (1);
 933                                 if (len <= 0) {
 934                                         close_socket(&sockets[i]);
 935                                         break;
 936                                 }
 937                                 buffer_consume(&sockets[i].output, len);
 938                         }
 939                         if (FD_ISSET(sockets[i].fd, readset)) {
 940                                 do {
 941                                         len = read(sockets[i].fd, buf, sizeof(buf));
 942                                         if (len == -1 && (errno == EAGAIN ||
 943                                             errno == EINTR))
 944                                                 continue;
 945                                         break;
 946                                 } while (1);
 947                                 if (len <= 0) {
 948                                         close_socket(&sockets[i]);
 949                                         break;
 950                                 }
 951                                 buffer_append(&sockets[i].input, buf, len);
 952                                 process_message(&sockets[i]);
 953                         }
 954                         break;
 955                 default:
 956                         fatal("Unknown type %d", sockets[i].type);
 957                 }
 958 }
 959
 960 static void
 961 cleanup_socket(void)
 962 {
 963         if (socket_name[0])
 964                 unlink(socket_name);
 965         if (socket_dir[0])
 966                 rmdir(socket_dir);
 967 }
 968
 969 void
 970 cleanup_exit(int i)
 971 {
 972         cleanup_socket();
 973         _exit(i);
 974 }
 975
 976 /*ARGSUSED*/
 977 static void
 978 cleanup_handler(int sig)
 979 {
 980         cleanup_socket();
 981         _exit(2);
 982 }
 983
 984 /*ARGSUSED*/
 985 static void
 986 check_parent_exists(int sig)
 987 {
 988         int save_errno = errno;
 989
 990         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 991                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 992                 cleanup_handler(sig); /* safe */
 993         }
 994         mysignal(SIGALRM, check_parent_exists);
 995         alarm(10);
 996         errno = save_errno;
 997 }
 998
 999 static void
1000 usage(void)
1001 {
1002         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
1003             __progname);
1004         fprintf(stderr, "Options:\n");
1005         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1006         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1007         fprintf(stderr, "  -k          Kill the current agent.\n");
1008         fprintf(stderr, "  -d          Debug mode.\n");
1009         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1010         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1011         exit(1);
1012 }
1013
1014 int
1015 main(int ac, char **av)
1016 {
1017         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1018         int sock, fd,  ch;
1019         u_int nalloc;
1020         char *shell, *format, *pidstr, *agentsocket = NULL;
1021         fd_set *readsetp = NULL, *writesetp = NULL;
1022         struct sockaddr_un sunaddr;
1023 #ifdef HAVE_SETRLIMIT
1024         struct rlimit rlim;
1025 #endif
1026         int prev_mask;
1027         extern int optind;
1028         extern char *optarg;
1029         pid_t pid;
1030         char pidstrbuf[1 + 3 * sizeof pid];
1031
1032         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1033         sanitise_stdfd();
1034
1035         /* drop */
1036         setegid(getgid());
1037         setgid(getgid());
1038
1039 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1040         /* Disable ptrace on Linux without sgid bit */
1041         prctl(PR_SET_DUMPABLE, 0);
1042 #endif
1043
1044         SSLeay_add_all_algorithms();
1045
1046         __progname = ssh_get_progname(av[0]);
1047         init_rng();
1048         seed_rng();
1049
1050         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1051                 switch (ch) {
1052                 case 'c':
1053                         if (s_flag)
1054                                 usage();
1055                         c_flag++;
1056                         break;
1057                 case 'k':
1058                         k_flag++;
1059                         break;
1060                 case 's':
1061                         if (c_flag)
1062                                 usage();
1063                         s_flag++;
1064                         break;
1065                 case 'd':
1066                         if (d_flag)
1067                                 usage();
1068                         d_flag++;
1069                         break;
1070                 case 'a':
1071                         agentsocket = optarg;
1072                         break;
1073                 case 't':
1074                         if ((lifetime = convtime(optarg)) == -1) {
1075                                 fprintf(stderr, "Invalid lifetime\n");
1076                                 usage();
1077                         }
1078                         break;
1079                 default:
1080                         usage();
1081                 }
1082         }
1083         ac -= optind;
1084         av += optind;
1085
1086         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1087                 usage();
1088
1089         if (ac == 0 && !c_flag && !s_flag) {
1090                 shell = getenv("SHELL");
1091                 if (shell != NULL &&
1092                     strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1093                         c_flag = 1;
1094         }
1095         if (k_flag) {
1096                 const char *errstr = NULL;
1097
1098                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1099                 if (pidstr == NULL) {
1100                         fprintf(stderr, "%s not set, cannot kill agent\n",
1101                             SSH_AGENTPID_ENV_NAME);
1102                         exit(1);
1103                 }
1104                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1105                 if (errstr) {
1106                         fprintf(stderr,
1107                             "%s=\"%s\", which is not a good PID: %s\n",
1108                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1109                         exit(1);
1110                 }
1111                 if (kill(pid, SIGTERM) == -1) {
1112                         perror("kill");
1113                         exit(1);
1114                 }
1115                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1116                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1117                 printf(format, SSH_AGENTPID_ENV_NAME);
1118                 printf("echo Agent pid %ld killed;\n", (long)pid);
1119                 exit(0);
1120         }
1121         parent_pid = getpid();
1122
1123         if (agentsocket == NULL) {
1124                 /* Create private directory for agent socket */
1125                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1126                 if (mkdtemp(socket_dir) == NULL) {
1127                         perror("mkdtemp: private socket dir");
1128                         exit(1);
1129                 }
1130                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1131                     (long)parent_pid);
1132         } else {
1133                 /* Try to use specified agent socket */
1134                 socket_dir[0] = '\0';
1135                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1136         }
1137
1138         /*
1139          * Create socket early so it will exist before command gets run from
1140          * the parent.
1141          */
1142         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1143         if (sock < 0) {
1144                 perror("socket");
1145                 *socket_name = '\0'; /* Don't unlink any existing file */
1146                 cleanup_exit(1);
1147         }
1148         memset(&sunaddr, 0, sizeof(sunaddr));
1149         sunaddr.sun_family = AF_UNIX;
1150         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1151         prev_mask = umask(0177);
1152         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1153                 perror("bind");
1154                 *socket_name = '\0'; /* Don't unlink any existing file */
1155                 umask(prev_mask);
1156                 cleanup_exit(1);
1157         }
1158         umask(prev_mask);
1159         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1160                 perror("listen");
1161                 cleanup_exit(1);
1162         }
1163
1164         /*
1165          * Fork, and have the parent execute the command, if any, or present
1166          * the socket data.  The child continues as the authentication agent.
1167          */
1168         if (d_flag) {
1169                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1170                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1171                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1172                     SSH_AUTHSOCKET_ENV_NAME);
1173                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1174                 goto skip;
1175         }
1176         pid = fork();
1177         if (pid == -1) {
1178                 perror("fork");
1179                 cleanup_exit(1);
1180         }
1181         if (pid != 0) {         /* Parent - execute the given command. */
1182                 close(sock);
1183                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1184                 if (ac == 0) {
1185                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1186                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1187                             SSH_AUTHSOCKET_ENV_NAME);
1188                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1189                             SSH_AGENTPID_ENV_NAME);
1190                         printf("echo Agent pid %ld;\n", (long)pid);
1191                         exit(0);
1192                 }
1193                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1194                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1195                         perror("setenv");
1196                         exit(1);
1197                 }
1198                 execvp(av[0], av);
1199                 perror(av[0]);
1200                 exit(1);
1201         }
1202         /* child */
1203         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1204
1205         if (setsid() == -1) {
1206                 error("setsid: %s", strerror(errno));
1207                 cleanup_exit(1);
1208         }
1209
1210         (void)chdir("/");
1211         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1212                 /* XXX might close listen socket */
1213                 (void)dup2(fd, STDIN_FILENO);
1214                 (void)dup2(fd, STDOUT_FILENO);
1215                 (void)dup2(fd, STDERR_FILENO);
1216                 if (fd > 2)
1217                         close(fd);
1218         }
1219
1220 #ifdef HAVE_SETRLIMIT
1221         /* deny core dumps, since memory contains unencrypted private keys */
1222         rlim.rlim_cur = rlim.rlim_max = 0;
1223         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1224                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1225                 cleanup_exit(1);
1226         }
1227 #endif
1228
1229 skip:
1230         new_socket(AUTH_SOCKET, sock);
1231         if (ac > 0) {
1232                 mysignal(SIGALRM, check_parent_exists);
1233                 alarm(10);
1234         }
1235         idtab_init();
1236         if (!d_flag)
1237                 signal(SIGINT, SIG_IGN);
1238         signal(SIGPIPE, SIG_IGN);
1239         signal(SIGHUP, cleanup_handler);
1240         signal(SIGTERM, cleanup_handler);
1241         nalloc = 0;
1242
1243         while (1) {
1244                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1245                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1246                         if (errno == EINTR)
1247                                 continue;
1248                         fatal("select: %s", strerror(errno));
1249                 }
1250                 after_select(readsetp, writesetp);
1251         }
1252         /* NOTREACHED */
1253 }