crypto/openssh/ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.159 2008/06/28 14:05:15 djm 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 __RCSID("$FreeBSD$");
  39
  40 #include <sys/types.h>
  41 #include <sys/param.h>
  42 #include <sys/resource.h>
  43 #include <sys/stat.h>
  44 #include <sys/socket.h>
  45 #ifdef HAVE_SYS_TIME_H
  46 # include <sys/time.h>
  47 #endif
  48 #ifdef HAVE_SYS_UN_H
  49 # include <sys/un.h>
  50 #endif
  51 #include "openbsd-compat/sys-queue.h"
  52
  53 #include <openssl/evp.h>
  54 #include <openssl/md5.h>
  55 #include "openbsd-compat/openssl-compat.h"
  56
  57 #include <errno.h>
  58 #include <fcntl.h>
  59 #ifdef HAVE_PATHS_H
  60 # include <paths.h>
  61 #endif
  62 #include <signal.h>
  63 #include <stdarg.h>
  64 #include <stdio.h>
  65 #include <stdlib.h>
  66 #include <time.h>
  67 #include <string.h>
  68 #include <unistd.h>
  69
  70 #include "xmalloc.h"
  71 #include "ssh.h"
  72 #include "rsa.h"
  73 #include "buffer.h"
  74 #include "key.h"
  75 #include "authfd.h"
  76 #include "compat.h"
  77 #include "log.h"
  78 #include "misc.h"
  79
  80 #ifdef SMARTCARD
  81 #include "scard.h"
  82 #endif
  83
  84 #if defined(HAVE_SYS_PRCTL_H)
  85 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  86 #endif
  87
  88 typedef enum {
  89         AUTH_UNUSED,
  90         AUTH_SOCKET,
  91         AUTH_CONNECTION
  92 } sock_type;
  93
  94 typedef struct {
  95         int fd;
  96         sock_type type;
  97         Buffer input;
  98         Buffer output;
  99         Buffer request;
 100 } SocketEntry;
 101
 102 u_int sockets_alloc = 0;
 103 SocketEntry *sockets = NULL;
 104
 105 typedef struct identity {
 106         TAILQ_ENTRY(identity) next;
 107         Key *key;
 108         char *comment;
 109         u_int death;
 110         u_int confirm;
 111 } Identity;
 112
 113 typedef struct {
 114         int nentries;
 115         TAILQ_HEAD(idqueue, identity) idlist;
 116 } Idtab;
 117
 118 /* private key table, one per protocol version */
 119 Idtab idtable[3];
 120
 121 int max_fd = 0;
 122
 123 /* pid of shell == parent of agent */
 124 pid_t parent_pid = -1;
 125 u_int parent_alive_interval = 0;
 126
 127 /* pathname and directory for AUTH_SOCKET */
 128 char socket_name[MAXPATHLEN];
 129 char socket_dir[MAXPATHLEN];
 130
 131 /* locking */
 132 int locked = 0;
 133 char *lock_passwd = NULL;
 134
 135 extern char *__progname;
 136
 137 /* Default lifetime (0 == forever) */
 138 static int lifetime = 0;
 139
 140 static void
 141 close_socket(SocketEntry *e)
 142 {
 143         close(e->fd);
 144         e->fd = -1;
 145         e->type = AUTH_UNUSED;
 146         buffer_free(&e->input);
 147         buffer_free(&e->output);
 148         buffer_free(&e->request);
 149 }
 150
 151 static void
 152 idtab_init(void)
 153 {
 154         int i;
 155
 156         for (i = 0; i <=2; i++) {
 157                 TAILQ_INIT(&idtable[i].idlist);
 158                 idtable[i].nentries = 0;
 159         }
 160 }
 161
 162 /* return private key table for requested protocol version */
 163 static Idtab *
 164 idtab_lookup(int version)
 165 {
 166         if (version < 1 || version > 2)
 167                 fatal("internal error, bad protocol version %d", version);
 168         return &idtable[version];
 169 }
 170
 171 static void
 172 free_identity(Identity *id)
 173 {
 174         key_free(id->key);
 175         xfree(id->comment);
 176         xfree(id);
 177 }
 178
 179 /* return matching private key for given public key */
 180 static Identity *
 181 lookup_identity(Key *key, int version)
 182 {
 183         Identity *id;
 184
 185         Idtab *tab = idtab_lookup(version);
 186         TAILQ_FOREACH(id, &tab->idlist, next) {
 187                 if (key_equal(key, id->key))
 188                         return (id);
 189         }
 190         return (NULL);
 191 }
 192
 193 /* Check confirmation of keysign request */
 194 static int
 195 confirm_key(Identity *id)
 196 {
 197         char *p;
 198         int ret = -1;
 199
 200         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 201         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 202             id->comment, p))
 203                 ret = 0;
 204         xfree(p);
 205
 206         return (ret);
 207 }
 208
 209 /* send list of supported public keys to 'client' */
 210 static void
 211 process_request_identities(SocketEntry *e, int version)
 212 {
 213         Idtab *tab = idtab_lookup(version);
 214         Identity *id;
 215         Buffer msg;
 216
 217         buffer_init(&msg);
 218         buffer_put_char(&msg, (version == 1) ?
 219             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 220         buffer_put_int(&msg, tab->nentries);
 221         TAILQ_FOREACH(id, &tab->idlist, next) {
 222                 if (id->key->type == KEY_RSA1) {
 223                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 224                         buffer_put_bignum(&msg, id->key->rsa->e);
 225                         buffer_put_bignum(&msg, id->key->rsa->n);
 226                 } else {
 227                         u_char *blob;
 228                         u_int blen;
 229                         key_to_blob(id->key, &blob, &blen);
 230                         buffer_put_string(&msg, blob, blen);
 231                         xfree(blob);
 232                 }
 233                 buffer_put_cstring(&msg, id->comment);
 234         }
 235         buffer_put_int(&e->output, buffer_len(&msg));
 236         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 237         buffer_free(&msg);
 238 }
 239
 240 /* ssh1 only */
 241 static void
 242 process_authentication_challenge1(SocketEntry *e)
 243 {
 244         u_char buf[32], mdbuf[16], session_id[16];
 245         u_int response_type;
 246         BIGNUM *challenge;
 247         Identity *id;
 248         int i, len;
 249         Buffer msg;
 250         MD5_CTX md;
 251         Key *key;
 252
 253         buffer_init(&msg);
 254         key = key_new(KEY_RSA1);
 255         if ((challenge = BN_new()) == NULL)
 256                 fatal("process_authentication_challenge1: BN_new failed");
 257
 258         (void) buffer_get_int(&e->request);                     /* ignored */
 259         buffer_get_bignum(&e->request, key->rsa->e);
 260         buffer_get_bignum(&e->request, key->rsa->n);
 261         buffer_get_bignum(&e->request, challenge);
 262
 263         /* Only protocol 1.1 is supported */
 264         if (buffer_len(&e->request) == 0)
 265                 goto failure;
 266         buffer_get(&e->request, session_id, 16);
 267         response_type = buffer_get_int(&e->request);
 268         if (response_type != 1)
 269                 goto failure;
 270
 271         id = lookup_identity(key, 1);
 272         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 273                 Key *private = id->key;
 274                 /* Decrypt the challenge using the private key. */
 275                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 276                         goto failure;
 277
 278                 /* The response is MD5 of decrypted challenge plus session id. */
 279                 len = BN_num_bytes(challenge);
 280                 if (len <= 0 || len > 32) {
 281                         logit("process_authentication_challenge: bad challenge length %d", len);
 282                         goto failure;
 283                 }
 284                 memset(buf, 0, 32);
 285                 BN_bn2bin(challenge, buf + 32 - len);
 286                 MD5_Init(&md);
 287                 MD5_Update(&md, buf, 32);
 288                 MD5_Update(&md, session_id, 16);
 289                 MD5_Final(mdbuf, &md);
 290
 291                 /* Send the response. */
 292                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 293                 for (i = 0; i < 16; i++)
 294                         buffer_put_char(&msg, mdbuf[i]);
 295                 goto send;
 296         }
 297
 298 failure:
 299         /* Unknown identity or protocol error.  Send failure. */
 300         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 301 send:
 302         buffer_put_int(&e->output, buffer_len(&msg));
 303         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 304         key_free(key);
 305         BN_clear_free(challenge);
 306         buffer_free(&msg);
 307 }
 308
 309 /* ssh2 only */
 310 static void
 311 process_sign_request2(SocketEntry *e)
 312 {
 313         u_char *blob, *data, *signature = NULL;
 314         u_int blen, dlen, slen = 0;
 315         extern int datafellows;
 316         int odatafellows;
 317         int ok = -1, flags;
 318         Buffer msg;
 319         Key *key;
 320
 321         datafellows = 0;
 322
 323         blob = buffer_get_string(&e->request, &blen);
 324         data = buffer_get_string(&e->request, &dlen);
 325
 326         flags = buffer_get_int(&e->request);
 327         odatafellows = datafellows;
 328         if (flags & SSH_AGENT_OLD_SIGNATURE)
 329                 datafellows = SSH_BUG_SIGBLOB;
 330
 331         key = key_from_blob(blob, blen);
 332         if (key != NULL) {
 333                 Identity *id = lookup_identity(key, 2);
 334                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 335                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 336                 key_free(key);
 337         }
 338         buffer_init(&msg);
 339         if (ok == 0) {
 340                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 341                 buffer_put_string(&msg, signature, slen);
 342         } else {
 343                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 344         }
 345         buffer_put_int(&e->output, buffer_len(&msg));
 346         buffer_append(&e->output, buffer_ptr(&msg),
 347             buffer_len(&msg));
 348         buffer_free(&msg);
 349         xfree(data);
 350         xfree(blob);
 351         if (signature != NULL)
 352                 xfree(signature);
 353         datafellows = odatafellows;
 354 }
 355
 356 /* shared */
 357 static void
 358 process_remove_identity(SocketEntry *e, int version)
 359 {
 360         u_int blen, bits;
 361         int success = 0;
 362         Key *key = NULL;
 363         u_char *blob;
 364
 365         switch (version) {
 366         case 1:
 367                 key = key_new(KEY_RSA1);
 368                 bits = buffer_get_int(&e->request);
 369                 buffer_get_bignum(&e->request, key->rsa->e);
 370                 buffer_get_bignum(&e->request, key->rsa->n);
 371
 372                 if (bits != key_size(key))
 373                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 374                             key_size(key), bits);
 375                 break;
 376         case 2:
 377                 blob = buffer_get_string(&e->request, &blen);
 378                 key = key_from_blob(blob, blen);
 379                 xfree(blob);
 380                 break;
 381         }
 382         if (key != NULL) {
 383                 Identity *id = lookup_identity(key, version);
 384                 if (id != NULL) {
 385                         /*
 386                          * We have this key.  Free the old key.  Since we
 387                          * don't want to leave empty slots in the middle of
 388                          * the array, we actually free the key there and move
 389                          * all the entries between the empty slot and the end
 390                          * of the array.
 391                          */
 392                         Idtab *tab = idtab_lookup(version);
 393                         if (tab->nentries < 1)
 394                                 fatal("process_remove_identity: "
 395                                     "internal error: tab->nentries %d",
 396                                     tab->nentries);
 397                         TAILQ_REMOVE(&tab->idlist, id, next);
 398                         free_identity(id);
 399                         tab->nentries--;
 400                         success = 1;
 401                 }
 402                 key_free(key);
 403         }
 404         buffer_put_int(&e->output, 1);
 405         buffer_put_char(&e->output,
 406             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 407 }
 408
 409 static void
 410 process_remove_all_identities(SocketEntry *e, int version)
 411 {
 412         Idtab *tab = idtab_lookup(version);
 413         Identity *id;
 414
 415         /* Loop over all identities and clear the keys. */
 416         for (id = TAILQ_FIRST(&tab->idlist); id;
 417             id = TAILQ_FIRST(&tab->idlist)) {
 418                 TAILQ_REMOVE(&tab->idlist, id, next);
 419                 free_identity(id);
 420         }
 421
 422         /* Mark that there are no identities. */
 423         tab->nentries = 0;
 424
 425         /* Send success. */
 426         buffer_put_int(&e->output, 1);
 427         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 428 }
 429
 430 /* removes expired keys and returns number of seconds until the next expiry */
 431 static u_int
 432 reaper(void)
 433 {
 434         u_int deadline = 0, now = time(NULL);
 435         Identity *id, *nxt;
 436         int version;
 437         Idtab *tab;
 438
 439         for (version = 1; version < 3; version++) {
 440                 tab = idtab_lookup(version);
 441                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 442                         nxt = TAILQ_NEXT(id, next);
 443                         if (id->death == 0)
 444                                 continue;
 445                         if (now >= id->death) {
 446                                 debug("expiring key '%s'", id->comment);
 447                                 TAILQ_REMOVE(&tab->idlist, id, next);
 448                                 free_identity(id);
 449                                 tab->nentries--;
 450                         } else
 451                                 deadline = (deadline == 0) ? id->death :
 452                                     MIN(deadline, id->death);
 453                 }
 454         }
 455         if (deadline == 0 || deadline <= now)
 456                 return 0;
 457         else
 458                 return (deadline - now);
 459 }
 460
 461 static void
 462 process_add_identity(SocketEntry *e, int version)
 463 {
 464         Idtab *tab = idtab_lookup(version);
 465         Identity *id;
 466         int type, success = 0, death = 0, confirm = 0;
 467         char *type_name, *comment;
 468         Key *k = NULL;
 469
 470         switch (version) {
 471         case 1:
 472                 k = key_new_private(KEY_RSA1);
 473                 (void) buffer_get_int(&e->request);             /* ignored */
 474                 buffer_get_bignum(&e->request, k->rsa->n);
 475                 buffer_get_bignum(&e->request, k->rsa->e);
 476                 buffer_get_bignum(&e->request, k->rsa->d);
 477                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 478
 479                 /* SSH and SSL have p and q swapped */
 480                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 481                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 482
 483                 /* Generate additional parameters */
 484                 rsa_generate_additional_parameters(k->rsa);
 485                 break;
 486         case 2:
 487                 type_name = buffer_get_string(&e->request, NULL);
 488                 type = key_type_from_name(type_name);
 489                 xfree(type_name);
 490                 switch (type) {
 491                 case KEY_DSA:
 492                         k = key_new_private(type);
 493                         buffer_get_bignum2(&e->request, k->dsa->p);
 494                         buffer_get_bignum2(&e->request, k->dsa->q);
 495                         buffer_get_bignum2(&e->request, k->dsa->g);
 496                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 497                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 498                         break;
 499                 case KEY_RSA:
 500                         k = key_new_private(type);
 501                         buffer_get_bignum2(&e->request, k->rsa->n);
 502                         buffer_get_bignum2(&e->request, k->rsa->e);
 503                         buffer_get_bignum2(&e->request, k->rsa->d);
 504                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 505                         buffer_get_bignum2(&e->request, k->rsa->p);
 506                         buffer_get_bignum2(&e->request, k->rsa->q);
 507
 508                         /* Generate additional parameters */
 509                         rsa_generate_additional_parameters(k->rsa);
 510                         break;
 511                 default:
 512                         buffer_clear(&e->request);
 513                         goto send;
 514                 }
 515                 break;
 516         }
 517         /* enable blinding */
 518         switch (k->type) {
 519         case KEY_RSA:
 520         case KEY_RSA1:
 521                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 522                         error("process_add_identity: RSA_blinding_on failed");
 523                         key_free(k);
 524                         goto send;
 525                 }
 526                 break;
 527         }
 528         comment = buffer_get_string(&e->request, NULL);
 529         if (k == NULL) {
 530                 xfree(comment);
 531                 goto send;
 532         }
 533         while (buffer_len(&e->request)) {
 534                 switch ((type = buffer_get_char(&e->request))) {
 535                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 536                         death = time(NULL) + buffer_get_int(&e->request);
 537                         break;
 538                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 539                         confirm = 1;
 540                         break;
 541                 default:
 542                         error("process_add_identity: "
 543                             "Unknown constraint type %d", type);
 544                         xfree(comment);
 545                         key_free(k);
 546                         goto send;
 547                 }
 548         }
 549         success = 1;
 550         if (lifetime && !death)
 551                 death = time(NULL) + lifetime;
 552         if ((id = lookup_identity(k, version)) == NULL) {
 553                 id = xmalloc(sizeof(Identity));
 554                 id->key = k;
 555                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 556                 /* Increment the number of identities. */
 557                 tab->nentries++;
 558         } else {
 559                 key_free(k);
 560                 xfree(id->comment);
 561         }
 562         id->comment = comment;
 563         id->death = death;
 564         id->confirm = confirm;
 565 send:
 566         buffer_put_int(&e->output, 1);
 567         buffer_put_char(&e->output,
 568             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 569 }
 570
 571 /* XXX todo: encrypt sensitive data with passphrase */
 572 static void
 573 process_lock_agent(SocketEntry *e, int lock)
 574 {
 575         int success = 0;
 576         char *passwd;
 577
 578         passwd = buffer_get_string(&e->request, NULL);
 579         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 580                 locked = 0;
 581                 memset(lock_passwd, 0, strlen(lock_passwd));
 582                 xfree(lock_passwd);
 583                 lock_passwd = NULL;
 584                 success = 1;
 585         } else if (!locked && lock) {
 586                 locked = 1;
 587                 lock_passwd = xstrdup(passwd);
 588                 success = 1;
 589         }
 590         memset(passwd, 0, strlen(passwd));
 591         xfree(passwd);
 592
 593         buffer_put_int(&e->output, 1);
 594         buffer_put_char(&e->output,
 595             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 596 }
 597
 598 static void
 599 no_identities(SocketEntry *e, u_int type)
 600 {
 601         Buffer msg;
 602
 603         buffer_init(&msg);
 604         buffer_put_char(&msg,
 605             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 606             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 607         buffer_put_int(&msg, 0);
 608         buffer_put_int(&e->output, buffer_len(&msg));
 609         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 610         buffer_free(&msg);
 611 }
 612
 613 #ifdef SMARTCARD
 614 static void
 615 process_add_smartcard_key(SocketEntry *e)
 616 {
 617         char *sc_reader_id = NULL, *pin;
 618         int i, type, version, success = 0, death = 0, confirm = 0;
 619         Key **keys, *k;
 620         Identity *id;
 621         Idtab *tab;
 622
 623         sc_reader_id = buffer_get_string(&e->request, NULL);
 624         pin = buffer_get_string(&e->request, NULL);
 625
 626         while (buffer_len(&e->request)) {
 627                 switch ((type = buffer_get_char(&e->request))) {
 628                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 629                         death = time(NULL) + buffer_get_int(&e->request);
 630                         break;
 631                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 632                         confirm = 1;
 633                         break;
 634                 default:
 635                         error("process_add_smartcard_key: "
 636                             "Unknown constraint type %d", type);
 637                         xfree(sc_reader_id);
 638                         xfree(pin);
 639                         goto send;
 640                 }
 641         }
 642         if (lifetime && !death)
 643                 death = time(NULL) + lifetime;
 644
 645         keys = sc_get_keys(sc_reader_id, pin);
 646         xfree(sc_reader_id);
 647         xfree(pin);
 648
 649         if (keys == NULL || keys[0] == NULL) {
 650                 error("sc_get_keys failed");
 651                 goto send;
 652         }
 653         for (i = 0; keys[i] != NULL; i++) {
 654                 k = keys[i];
 655                 version = k->type == KEY_RSA1 ? 1 : 2;
 656                 tab = idtab_lookup(version);
 657                 if (lookup_identity(k, version) == NULL) {
 658                         id = xmalloc(sizeof(Identity));
 659                         id->key = k;
 660                         id->comment = sc_get_key_label(k);
 661                         id->death = death;
 662                         id->confirm = confirm;
 663                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 664                         tab->nentries++;
 665                         success = 1;
 666                 } else {
 667                         key_free(k);
 668                 }
 669                 keys[i] = NULL;
 670         }
 671         xfree(keys);
 672 send:
 673         buffer_put_int(&e->output, 1);
 674         buffer_put_char(&e->output,
 675             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 676 }
 677
 678 static void
 679 process_remove_smartcard_key(SocketEntry *e)
 680 {
 681         char *sc_reader_id = NULL, *pin;
 682         int i, version, success = 0;
 683         Key **keys, *k = NULL;
 684         Identity *id;
 685         Idtab *tab;
 686
 687         sc_reader_id = buffer_get_string(&e->request, NULL);
 688         pin = buffer_get_string(&e->request, NULL);
 689         keys = sc_get_keys(sc_reader_id, pin);
 690         xfree(sc_reader_id);
 691         xfree(pin);
 692
 693         if (keys == NULL || keys[0] == NULL) {
 694                 error("sc_get_keys failed");
 695                 goto send;
 696         }
 697         for (i = 0; keys[i] != NULL; i++) {
 698                 k = keys[i];
 699                 version = k->type == KEY_RSA1 ? 1 : 2;
 700                 if ((id = lookup_identity(k, version)) != NULL) {
 701                         tab = idtab_lookup(version);
 702                         TAILQ_REMOVE(&tab->idlist, id, next);
 703                         tab->nentries--;
 704                         free_identity(id);
 705                         success = 1;
 706                 }
 707                 key_free(k);
 708                 keys[i] = NULL;
 709         }
 710         xfree(keys);
 711 send:
 712         buffer_put_int(&e->output, 1);
 713         buffer_put_char(&e->output,
 714             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 715 }
 716 #endif /* SMARTCARD */
 717
 718 /* dispatch incoming messages */
 719
 720 static void
 721 process_message(SocketEntry *e)
 722 {
 723         u_int msg_len, type;
 724         u_char *cp;
 725
 726         if (buffer_len(&e->input) < 5)
 727                 return;         /* Incomplete message. */
 728         cp = buffer_ptr(&e->input);
 729         msg_len = get_u32(cp);
 730         if (msg_len > 256 * 1024) {
 731                 close_socket(e);
 732                 return;
 733         }
 734         if (buffer_len(&e->input) < msg_len + 4)
 735                 return;
 736
 737         /* move the current input to e->request */
 738         buffer_consume(&e->input, 4);
 739         buffer_clear(&e->request);
 740         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 741         buffer_consume(&e->input, msg_len);
 742         type = buffer_get_char(&e->request);
 743
 744         /* check wheter agent is locked */
 745         if (locked && type != SSH_AGENTC_UNLOCK) {
 746                 buffer_clear(&e->request);
 747                 switch (type) {
 748                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 749                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 750                         /* send empty lists */
 751                         no_identities(e, type);
 752                         break;
 753                 default:
 754                         /* send a fail message for all other request types */
 755                         buffer_put_int(&e->output, 1);
 756                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 757                 }
 758                 return;
 759         }
 760
 761         debug("type %d", type);
 762         switch (type) {
 763         case SSH_AGENTC_LOCK:
 764         case SSH_AGENTC_UNLOCK:
 765                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 766                 break;
 767         /* ssh1 */
 768         case SSH_AGENTC_RSA_CHALLENGE:
 769                 process_authentication_challenge1(e);
 770                 break;
 771         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 772                 process_request_identities(e, 1);
 773                 break;
 774         case SSH_AGENTC_ADD_RSA_IDENTITY:
 775         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 776                 process_add_identity(e, 1);
 777                 break;
 778         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 779                 process_remove_identity(e, 1);
 780                 break;
 781         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 782                 process_remove_all_identities(e, 1);
 783                 break;
 784         /* ssh2 */
 785         case SSH2_AGENTC_SIGN_REQUEST:
 786                 process_sign_request2(e);
 787                 break;
 788         case SSH2_AGENTC_REQUEST_IDENTITIES:
 789                 process_request_identities(e, 2);
 790                 break;
 791         case SSH2_AGENTC_ADD_IDENTITY:
 792         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 793                 process_add_identity(e, 2);
 794                 break;
 795         case SSH2_AGENTC_REMOVE_IDENTITY:
 796                 process_remove_identity(e, 2);
 797                 break;
 798         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 799                 process_remove_all_identities(e, 2);
 800                 break;
 801 #ifdef SMARTCARD
 802         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 803         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 804                 process_add_smartcard_key(e);
 805                 break;
 806         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 807                 process_remove_smartcard_key(e);
 808                 break;
 809 #endif /* SMARTCARD */
 810         default:
 811                 /* Unknown message.  Respond with failure. */
 812                 error("Unknown message %d", type);
 813                 buffer_clear(&e->request);
 814                 buffer_put_int(&e->output, 1);
 815                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 816                 break;
 817         }
 818 }
 819
 820 static void
 821 new_socket(sock_type type, int fd)
 822 {
 823         u_int i, old_alloc, new_alloc;
 824
 825         set_nonblock(fd);
 826
 827         if (fd > max_fd)
 828                 max_fd = fd;
 829
 830         for (i = 0; i < sockets_alloc; i++)
 831                 if (sockets[i].type == AUTH_UNUSED) {
 832                         sockets[i].fd = fd;
 833                         buffer_init(&sockets[i].input);
 834                         buffer_init(&sockets[i].output);
 835                         buffer_init(&sockets[i].request);
 836                         sockets[i].type = type;
 837                         return;
 838                 }
 839         old_alloc = sockets_alloc;
 840         new_alloc = sockets_alloc + 10;
 841         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 842         for (i = old_alloc; i < new_alloc; i++)
 843                 sockets[i].type = AUTH_UNUSED;
 844         sockets_alloc = new_alloc;
 845         sockets[old_alloc].fd = fd;
 846         buffer_init(&sockets[old_alloc].input);
 847         buffer_init(&sockets[old_alloc].output);
 848         buffer_init(&sockets[old_alloc].request);
 849         sockets[old_alloc].type = type;
 850 }
 851
 852 static int
 853 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
 854     struct timeval **tvpp)
 855 {
 856         u_int i, sz, deadline;
 857         int n = 0;
 858         static struct timeval tv;
 859
 860         for (i = 0; i < sockets_alloc; i++) {
 861                 switch (sockets[i].type) {
 862                 case AUTH_SOCKET:
 863                 case AUTH_CONNECTION:
 864                         n = MAX(n, sockets[i].fd);
 865                         break;
 866                 case AUTH_UNUSED:
 867                         break;
 868                 default:
 869                         fatal("Unknown socket type %d", sockets[i].type);
 870                         break;
 871                 }
 872         }
 873
 874         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 875         if (*fdrp == NULL || sz > *nallocp) {
 876                 if (*fdrp)
 877                         xfree(*fdrp);
 878                 if (*fdwp)
 879                         xfree(*fdwp);
 880                 *fdrp = xmalloc(sz);
 881                 *fdwp = xmalloc(sz);
 882                 *nallocp = sz;
 883         }
 884         if (n < *fdl)
 885                 debug("XXX shrink: %d < %d", n, *fdl);
 886         *fdl = n;
 887         memset(*fdrp, 0, sz);
 888         memset(*fdwp, 0, sz);
 889
 890         for (i = 0; i < sockets_alloc; i++) {
 891                 switch (sockets[i].type) {
 892                 case AUTH_SOCKET:
 893                 case AUTH_CONNECTION:
 894                         FD_SET(sockets[i].fd, *fdrp);
 895                         if (buffer_len(&sockets[i].output) > 0)
 896                                 FD_SET(sockets[i].fd, *fdwp);
 897                         break;
 898                 default:
 899                         break;
 900                 }
 901         }
 902         deadline = reaper();
 903         if (parent_alive_interval != 0)
 904                 deadline = (deadline == 0) ? parent_alive_interval :
 905                     MIN(deadline, parent_alive_interval);
 906         if (deadline == 0) {
 907                 *tvpp = NULL;
 908         } else {
 909                 tv.tv_sec = deadline;
 910                 tv.tv_usec = 0;
 911                 *tvpp = &tv;
 912         }
 913         return (1);
 914 }
 915
 916 static void
 917 after_select(fd_set *readset, fd_set *writeset)
 918 {
 919         struct sockaddr_un sunaddr;
 920         socklen_t slen;
 921         char buf[1024];
 922         int len, sock;
 923         u_int i;
 924         uid_t euid;
 925         gid_t egid;
 926
 927         for (i = 0; i < sockets_alloc; i++)
 928                 switch (sockets[i].type) {
 929                 case AUTH_UNUSED:
 930                         break;
 931                 case AUTH_SOCKET:
 932                         if (FD_ISSET(sockets[i].fd, readset)) {
 933                                 slen = sizeof(sunaddr);
 934                                 sock = accept(sockets[i].fd,
 935                                     (struct sockaddr *)&sunaddr, &slen);
 936                                 if (sock < 0) {
 937                                         error("accept from AUTH_SOCKET: %s",
 938                                             strerror(errno));
 939                                         break;
 940                                 }
 941                                 if (getpeereid(sock, &euid, &egid) < 0) {
 942                                         error("getpeereid %d failed: %s",
 943                                             sock, strerror(errno));
 944                                         close(sock);
 945                                         break;
 946                                 }
 947                                 if ((euid != 0) && (getuid() != euid)) {
 948                                         error("uid mismatch: "
 949                                             "peer euid %u != uid %u",
 950                                             (u_int) euid, (u_int) getuid());
 951                                         close(sock);
 952                                         break;
 953                                 }
 954                                 new_socket(AUTH_CONNECTION, sock);
 955                         }
 956                         break;
 957                 case AUTH_CONNECTION:
 958                         if (buffer_len(&sockets[i].output) > 0 &&
 959                             FD_ISSET(sockets[i].fd, writeset)) {
 960                                 do {
 961                                         len = write(sockets[i].fd,
 962                                             buffer_ptr(&sockets[i].output),
 963                                             buffer_len(&sockets[i].output));
 964                                         if (len == -1 && (errno == EAGAIN ||
 965                                             errno == EINTR ||
 966                                             errno == EWOULDBLOCK))
 967                                                 continue;
 968                                         break;
 969                                 } while (1);
 970                                 if (len <= 0) {
 971                                         close_socket(&sockets[i]);
 972                                         break;
 973                                 }
 974                                 buffer_consume(&sockets[i].output, len);
 975                         }
 976                         if (FD_ISSET(sockets[i].fd, readset)) {
 977                                 do {
 978                                         len = read(sockets[i].fd, buf, sizeof(buf));
 979                                         if (len == -1 && (errno == EAGAIN ||
 980                                             errno == EINTR ||
 981                                             errno == EWOULDBLOCK))
 982                                                 continue;
 983                                         break;
 984                                 } while (1);
 985                                 if (len <= 0) {
 986                                         close_socket(&sockets[i]);
 987                                         break;
 988                                 }
 989                                 buffer_append(&sockets[i].input, buf, len);
 990                                 process_message(&sockets[i]);
 991                         }
 992                         break;
 993                 default:
 994                         fatal("Unknown type %d", sockets[i].type);
 995                 }
 996 }
 997
 998 static void
 999 cleanup_socket(void)
1000 {
1001         if (socket_name[0])
1002                 unlink(socket_name);
1003         if (socket_dir[0])
1004                 rmdir(socket_dir);
1005 }
1006
1007 void
1008 cleanup_exit(int i)
1009 {
1010         cleanup_socket();
1011         _exit(i);
1012 }
1013
1014 /*ARGSUSED*/
1015 static void
1016 cleanup_handler(int sig)
1017 {
1018         cleanup_socket();
1019         _exit(2);
1020 }
1021
1022 static void
1023 check_parent_exists(void)
1024 {
1025         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
1026                 /* printf("Parent has died - Authentication agent exiting.\n"); */
1027                 cleanup_socket();
1028                 _exit(2);
1029         }
1030 }
1031
1032 static void
1033 usage(void)
1034 {
1035         fprintf(stderr, "usage: %s [options] [command [arg ...]]\n",
1036             __progname);
1037         fprintf(stderr, "Options:\n");
1038         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1039         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1040         fprintf(stderr, "  -k          Kill the current agent.\n");
1041         fprintf(stderr, "  -d          Debug mode.\n");
1042         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1043         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1044         exit(1);
1045 }
1046
1047 int
1048 main(int ac, char **av)
1049 {
1050         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1051         int sock, fd, ch, result, saved_errno;
1052         u_int nalloc;
1053         char *shell, *format, *pidstr, *agentsocket = NULL;
1054         fd_set *readsetp = NULL, *writesetp = NULL;
1055         struct sockaddr_un sunaddr;
1056 #ifdef HAVE_SETRLIMIT
1057         struct rlimit rlim;
1058 #endif
1059         int prev_mask;
1060         extern int optind;
1061         extern char *optarg;
1062         pid_t pid;
1063         char pidstrbuf[1 + 3 * sizeof pid];
1064         struct timeval *tvp = NULL;
1065
1066         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1067         sanitise_stdfd();
1068
1069         /* drop */
1070         setegid(getgid());
1071         setgid(getgid());
1072         setuid(geteuid());
1073
1074 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1075         /* Disable ptrace on Linux without sgid bit */
1076         prctl(PR_SET_DUMPABLE, 0);
1077 #endif
1078
1079         SSLeay_add_all_algorithms();
1080
1081         __progname = ssh_get_progname(av[0]);
1082         init_rng();
1083         seed_rng();
1084
1085         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1086                 switch (ch) {
1087                 case 'c':
1088                         if (s_flag)
1089                                 usage();
1090                         c_flag++;
1091                         break;
1092                 case 'k':
1093                         k_flag++;
1094                         break;
1095                 case 's':
1096                         if (c_flag)
1097                                 usage();
1098                         s_flag++;
1099                         break;
1100                 case 'd':
1101                         if (d_flag)
1102                                 usage();
1103                         d_flag++;
1104                         break;
1105                 case 'a':
1106                         agentsocket = optarg;
1107                         break;
1108                 case 't':
1109                         if ((lifetime = convtime(optarg)) == -1) {
1110                                 fprintf(stderr, "Invalid lifetime\n");
1111                                 usage();
1112                         }
1113                         break;
1114                 default:
1115                         usage();
1116                 }
1117         }
1118         ac -= optind;
1119         av += optind;
1120
1121         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1122                 usage();
1123
1124         if (ac == 0 && !c_flag && !s_flag) {
1125                 shell = getenv("SHELL");
1126                 if (shell != NULL &&
1127                     strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1128                         c_flag = 1;
1129         }
1130         if (k_flag) {
1131                 const char *errstr = NULL;
1132
1133                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1134                 if (pidstr == NULL) {
1135                         fprintf(stderr, "%s not set, cannot kill agent\n",
1136                             SSH_AGENTPID_ENV_NAME);
1137                         exit(1);
1138                 }
1139                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1140                 if (errstr) {
1141                         fprintf(stderr,
1142                             "%s=\"%s\", which is not a good PID: %s\n",
1143                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1144                         exit(1);
1145                 }
1146                 if (kill(pid, SIGTERM) == -1) {
1147                         perror("kill");
1148                         exit(1);
1149                 }
1150                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1151                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1152                 printf(format, SSH_AGENTPID_ENV_NAME);
1153                 printf("echo Agent pid %ld killed;\n", (long)pid);
1154                 exit(0);
1155         }
1156         parent_pid = getpid();
1157
1158         if (agentsocket == NULL) {
1159                 /* Create private directory for agent socket */
1160                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1161                 if (mkdtemp(socket_dir) == NULL) {
1162                         perror("mkdtemp: private socket dir");
1163                         exit(1);
1164                 }
1165                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1166                     (long)parent_pid);
1167         } else {
1168                 /* Try to use specified agent socket */
1169                 socket_dir[0] = '\0';
1170                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1171         }
1172
1173         /*
1174          * Create socket early so it will exist before command gets run from
1175          * the parent.
1176          */
1177         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1178         if (sock < 0) {
1179                 perror("socket");
1180                 *socket_name = '\0'; /* Don't unlink any existing file */
1181                 cleanup_exit(1);
1182         }
1183         memset(&sunaddr, 0, sizeof(sunaddr));
1184         sunaddr.sun_family = AF_UNIX;
1185         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1186         prev_mask = umask(0177);
1187         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1188                 perror("bind");
1189                 *socket_name = '\0'; /* Don't unlink any existing file */
1190                 umask(prev_mask);
1191                 cleanup_exit(1);
1192         }
1193         umask(prev_mask);
1194         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1195                 perror("listen");
1196                 cleanup_exit(1);
1197         }
1198
1199         /*
1200          * Fork, and have the parent execute the command, if any, or present
1201          * the socket data.  The child continues as the authentication agent.
1202          */
1203         if (d_flag) {
1204                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1205                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1206                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1207                     SSH_AUTHSOCKET_ENV_NAME);
1208                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1209                 goto skip;
1210         }
1211         pid = fork();
1212         if (pid == -1) {
1213                 perror("fork");
1214                 cleanup_exit(1);
1215         }
1216         if (pid != 0) {         /* Parent - execute the given command. */
1217                 close(sock);
1218                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1219                 if (ac == 0) {
1220                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1221                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1222                             SSH_AUTHSOCKET_ENV_NAME);
1223                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1224                             SSH_AGENTPID_ENV_NAME);
1225                         printf("echo Agent pid %ld;\n", (long)pid);
1226                         exit(0);
1227                 }
1228                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1229                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1230                         perror("setenv");
1231                         exit(1);
1232                 }
1233                 execvp(av[0], av);
1234                 perror(av[0]);
1235                 exit(1);
1236         }
1237         /* child */
1238         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1239
1240         if (setsid() == -1) {
1241                 error("setsid: %s", strerror(errno));
1242                 cleanup_exit(1);
1243         }
1244
1245         (void)chdir("/");
1246         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1247                 /* XXX might close listen socket */
1248                 (void)dup2(fd, STDIN_FILENO);
1249                 (void)dup2(fd, STDOUT_FILENO);
1250                 (void)dup2(fd, STDERR_FILENO);
1251                 if (fd > 2)
1252                         close(fd);
1253         }
1254
1255 #ifdef HAVE_SETRLIMIT
1256         /* deny core dumps, since memory contains unencrypted private keys */
1257         rlim.rlim_cur = rlim.rlim_max = 0;
1258         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1259                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1260                 cleanup_exit(1);
1261         }
1262 #endif
1263
1264 skip:
1265         new_socket(AUTH_SOCKET, sock);
1266         if (ac > 0)
1267                 parent_alive_interval = 10;
1268         idtab_init();
1269         if (!d_flag)
1270                 signal(SIGINT, SIG_IGN);
1271         signal(SIGPIPE, SIG_IGN);
1272         signal(SIGHUP, cleanup_handler);
1273         signal(SIGTERM, cleanup_handler);
1274         nalloc = 0;
1275
1276         while (1) {
1277                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1278                 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1279                 saved_errno = errno;
1280                 if (parent_alive_interval != 0)
1281                         check_parent_exists();
1282                 (void) reaper();        /* remove expired keys */
1283                 if (result < 0) {
1284                         if (saved_errno == EINTR)
1285                                 continue;
1286                         fatal("select: %s", strerror(saved_errno));
1287                 } else if (result > 0)
1288                         after_select(readsetp, writesetp);
1289         }
1290         /* NOTREACHED */
1291 }