crypto/openssh/ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.181 2013/12/19 01:19:41 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 ENABLE_PKCS11
  81 #include "ssh-pkcs11.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         char *provider;
 110         time_t death;
 111         u_int confirm;
 112 } Identity;
 113
 114 typedef struct {
 115         int nentries;
 116         TAILQ_HEAD(idqueue, identity) idlist;
 117 } Idtab;
 118
 119 /* private key table, one per protocol version */
 120 Idtab idtable[3];
 121
 122 int max_fd = 0;
 123
 124 /* pid of shell == parent of agent */
 125 pid_t parent_pid = -1;
 126 time_t parent_alive_interval = 0;
 127
 128 /* pathname and directory for AUTH_SOCKET */
 129 char socket_name[MAXPATHLEN];
 130 char socket_dir[MAXPATHLEN];
 131
 132 /* locking */
 133 int locked = 0;
 134 char *lock_passwd = NULL;
 135
 136 extern char *__progname;
 137
 138 /* Default lifetime in seconds (0 == forever) */
 139 static long lifetime = 0;
 140
 141 /*
 142  * Client connection count; incremented in new_socket() and decremented in
 143  * close_socket().  When it reaches 0, ssh-agent will exit.  Since it is
 144  * normally initialized to 1, it will never reach 0.  However, if the -x
 145  * option is specified, it is initialized to 0 in main(); in that case,
 146  * ssh-agent will exit as soon as it has had at least one client but no
 147  * longer has any.
 148  */
 149 static int xcount = 1;
 150
 151 static void
 152 close_socket(SocketEntry *e)
 153 {
 154         int last = 0;
 155
 156         if (e->type == AUTH_CONNECTION) {
 157                 debug("xcount %d -> %d", xcount, xcount - 1);
 158                 if (--xcount == 0)
 159                         last = 1;
 160         }
 161         close(e->fd);
 162         e->fd = -1;
 163         e->type = AUTH_UNUSED;
 164         buffer_free(&e->input);
 165         buffer_free(&e->output);
 166         buffer_free(&e->request);
 167         if (last)
 168                 cleanup_exit(0);
 169 }
 170
 171 static void
 172 idtab_init(void)
 173 {
 174         int i;
 175
 176         for (i = 0; i <=2; i++) {
 177                 TAILQ_INIT(&idtable[i].idlist);
 178                 idtable[i].nentries = 0;
 179         }
 180 }
 181
 182 /* return private key table for requested protocol version */
 183 static Idtab *
 184 idtab_lookup(int version)
 185 {
 186         if (version < 1 || version > 2)
 187                 fatal("internal error, bad protocol version %d", version);
 188         return &idtable[version];
 189 }
 190
 191 static void
 192 free_identity(Identity *id)
 193 {
 194         key_free(id->key);
 195         free(id->provider);
 196         free(id->comment);
 197         free(id);
 198 }
 199
 200 /* return matching private key for given public key */
 201 static Identity *
 202 lookup_identity(Key *key, int version)
 203 {
 204         Identity *id;
 205
 206         Idtab *tab = idtab_lookup(version);
 207         TAILQ_FOREACH(id, &tab->idlist, next) {
 208                 if (key_equal(key, id->key))
 209                         return (id);
 210         }
 211         return (NULL);
 212 }
 213
 214 /* Check confirmation of keysign request */
 215 static int
 216 confirm_key(Identity *id)
 217 {
 218         char *p;
 219         int ret = -1;
 220
 221         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 222         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 223             id->comment, p))
 224                 ret = 0;
 225         free(p);
 226
 227         return (ret);
 228 }
 229
 230 /* send list of supported public keys to 'client' */
 231 static void
 232 process_request_identities(SocketEntry *e, int version)
 233 {
 234         Idtab *tab = idtab_lookup(version);
 235         Identity *id;
 236         Buffer msg;
 237
 238         buffer_init(&msg);
 239         buffer_put_char(&msg, (version == 1) ?
 240             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 241         buffer_put_int(&msg, tab->nentries);
 242         TAILQ_FOREACH(id, &tab->idlist, next) {
 243                 if (id->key->type == KEY_RSA1) {
 244                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 245                         buffer_put_bignum(&msg, id->key->rsa->e);
 246                         buffer_put_bignum(&msg, id->key->rsa->n);
 247                 } else {
 248                         u_char *blob;
 249                         u_int blen;
 250                         key_to_blob(id->key, &blob, &blen);
 251                         buffer_put_string(&msg, blob, blen);
 252                         free(blob);
 253                 }
 254                 buffer_put_cstring(&msg, id->comment);
 255         }
 256         buffer_put_int(&e->output, buffer_len(&msg));
 257         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 258         buffer_free(&msg);
 259 }
 260
 261 /* ssh1 only */
 262 static void
 263 process_authentication_challenge1(SocketEntry *e)
 264 {
 265         u_char buf[32], mdbuf[16], session_id[16];
 266         u_int response_type;
 267         BIGNUM *challenge;
 268         Identity *id;
 269         int i, len;
 270         Buffer msg;
 271         MD5_CTX md;
 272         Key *key;
 273
 274         buffer_init(&msg);
 275         key = key_new(KEY_RSA1);
 276         if ((challenge = BN_new()) == NULL)
 277                 fatal("process_authentication_challenge1: BN_new failed");
 278
 279         (void) buffer_get_int(&e->request);                     /* ignored */
 280         buffer_get_bignum(&e->request, key->rsa->e);
 281         buffer_get_bignum(&e->request, key->rsa->n);
 282         buffer_get_bignum(&e->request, challenge);
 283
 284         /* Only protocol 1.1 is supported */
 285         if (buffer_len(&e->request) == 0)
 286                 goto failure;
 287         buffer_get(&e->request, session_id, 16);
 288         response_type = buffer_get_int(&e->request);
 289         if (response_type != 1)
 290                 goto failure;
 291
 292         id = lookup_identity(key, 1);
 293         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 294                 Key *private = id->key;
 295                 /* Decrypt the challenge using the private key. */
 296                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 297                         goto failure;
 298
 299                 /* The response is MD5 of decrypted challenge plus session id. */
 300                 len = BN_num_bytes(challenge);
 301                 if (len <= 0 || len > 32) {
 302                         logit("process_authentication_challenge: bad challenge length %d", len);
 303                         goto failure;
 304                 }
 305                 memset(buf, 0, 32);
 306                 BN_bn2bin(challenge, buf + 32 - len);
 307                 MD5_Init(&md);
 308                 MD5_Update(&md, buf, 32);
 309                 MD5_Update(&md, session_id, 16);
 310                 MD5_Final(mdbuf, &md);
 311
 312                 /* Send the response. */
 313                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 314                 for (i = 0; i < 16; i++)
 315                         buffer_put_char(&msg, mdbuf[i]);
 316                 goto send;
 317         }
 318
 319 failure:
 320         /* Unknown identity or protocol error.  Send failure. */
 321         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 322 send:
 323         buffer_put_int(&e->output, buffer_len(&msg));
 324         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 325         key_free(key);
 326         BN_clear_free(challenge);
 327         buffer_free(&msg);
 328 }
 329
 330 /* ssh2 only */
 331 static void
 332 process_sign_request2(SocketEntry *e)
 333 {
 334         u_char *blob, *data, *signature = NULL;
 335         u_int blen, dlen, slen = 0;
 336         extern int datafellows;
 337         int odatafellows;
 338         int ok = -1, flags;
 339         Buffer msg;
 340         Key *key;
 341
 342         datafellows = 0;
 343
 344         blob = buffer_get_string(&e->request, &blen);
 345         data = buffer_get_string(&e->request, &dlen);
 346
 347         flags = buffer_get_int(&e->request);
 348         odatafellows = datafellows;
 349         if (flags & SSH_AGENT_OLD_SIGNATURE)
 350                 datafellows = SSH_BUG_SIGBLOB;
 351
 352         key = key_from_blob(blob, blen);
 353         if (key != NULL) {
 354                 Identity *id = lookup_identity(key, 2);
 355                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 356                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 357                 key_free(key);
 358         }
 359         buffer_init(&msg);
 360         if (ok == 0) {
 361                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 362                 buffer_put_string(&msg, signature, slen);
 363         } else {
 364                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 365         }
 366         buffer_put_int(&e->output, buffer_len(&msg));
 367         buffer_append(&e->output, buffer_ptr(&msg),
 368             buffer_len(&msg));
 369         buffer_free(&msg);
 370         free(data);
 371         free(blob);
 372         free(signature);
 373         datafellows = odatafellows;
 374 }
 375
 376 /* shared */
 377 static void
 378 process_remove_identity(SocketEntry *e, int version)
 379 {
 380         u_int blen, bits;
 381         int success = 0;
 382         Key *key = NULL;
 383         u_char *blob;
 384
 385         switch (version) {
 386         case 1:
 387                 key = key_new(KEY_RSA1);
 388                 bits = buffer_get_int(&e->request);
 389                 buffer_get_bignum(&e->request, key->rsa->e);
 390                 buffer_get_bignum(&e->request, key->rsa->n);
 391
 392                 if (bits != key_size(key))
 393                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 394                             key_size(key), bits);
 395                 break;
 396         case 2:
 397                 blob = buffer_get_string(&e->request, &blen);
 398                 key = key_from_blob(blob, blen);
 399                 free(blob);
 400                 break;
 401         }
 402         if (key != NULL) {
 403                 Identity *id = lookup_identity(key, version);
 404                 if (id != NULL) {
 405                         /*
 406                          * We have this key.  Free the old key.  Since we
 407                          * don't want to leave empty slots in the middle of
 408                          * the array, we actually free the key there and move
 409                          * all the entries between the empty slot and the end
 410                          * of the array.
 411                          */
 412                         Idtab *tab = idtab_lookup(version);
 413                         if (tab->nentries < 1)
 414                                 fatal("process_remove_identity: "
 415                                     "internal error: tab->nentries %d",
 416                                     tab->nentries);
 417                         TAILQ_REMOVE(&tab->idlist, id, next);
 418                         free_identity(id);
 419                         tab->nentries--;
 420                         success = 1;
 421                 }
 422                 key_free(key);
 423         }
 424         buffer_put_int(&e->output, 1);
 425         buffer_put_char(&e->output,
 426             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 427 }
 428
 429 static void
 430 process_remove_all_identities(SocketEntry *e, int version)
 431 {
 432         Idtab *tab = idtab_lookup(version);
 433         Identity *id;
 434
 435         /* Loop over all identities and clear the keys. */
 436         for (id = TAILQ_FIRST(&tab->idlist); id;
 437             id = TAILQ_FIRST(&tab->idlist)) {
 438                 TAILQ_REMOVE(&tab->idlist, id, next);
 439                 free_identity(id);
 440         }
 441
 442         /* Mark that there are no identities. */
 443         tab->nentries = 0;
 444
 445         /* Send success. */
 446         buffer_put_int(&e->output, 1);
 447         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 448 }
 449
 450 /* removes expired keys and returns number of seconds until the next expiry */
 451 static time_t
 452 reaper(void)
 453 {
 454         time_t deadline = 0, now = monotime();
 455         Identity *id, *nxt;
 456         int version;
 457         Idtab *tab;
 458
 459         for (version = 1; version < 3; version++) {
 460                 tab = idtab_lookup(version);
 461                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 462                         nxt = TAILQ_NEXT(id, next);
 463                         if (id->death == 0)
 464                                 continue;
 465                         if (now >= id->death) {
 466                                 debug("expiring key '%s'", id->comment);
 467                                 TAILQ_REMOVE(&tab->idlist, id, next);
 468                                 free_identity(id);
 469                                 tab->nentries--;
 470                         } else
 471                                 deadline = (deadline == 0) ? id->death :
 472                                     MIN(deadline, id->death);
 473                 }
 474         }
 475         if (deadline == 0 || deadline <= now)
 476                 return 0;
 477         else
 478                 return (deadline - now);
 479 }
 480
 481 static void
 482 process_add_identity(SocketEntry *e, int version)
 483 {
 484         Idtab *tab = idtab_lookup(version);
 485         Identity *id;
 486         int type, success = 0, confirm = 0;
 487         char *comment;
 488         time_t death = 0;
 489         Key *k = NULL;
 490
 491         switch (version) {
 492         case 1:
 493                 k = key_new_private(KEY_RSA1);
 494                 (void) buffer_get_int(&e->request);             /* ignored */
 495                 buffer_get_bignum(&e->request, k->rsa->n);
 496                 buffer_get_bignum(&e->request, k->rsa->e);
 497                 buffer_get_bignum(&e->request, k->rsa->d);
 498                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 499
 500                 /* SSH and SSL have p and q swapped */
 501                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 502                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 503
 504                 /* Generate additional parameters */
 505                 rsa_generate_additional_parameters(k->rsa);
 506
 507                 /* enable blinding */
 508                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 509                         error("process_add_identity: RSA_blinding_on failed");
 510                         key_free(k);
 511                         goto send;
 512                 }
 513                 break;
 514         case 2:
 515                 k = key_private_deserialize(&e->request);
 516                 if (k == NULL) {
 517                         buffer_clear(&e->request);
 518                         goto send;
 519                 }
 520                 break;
 521         }
 522         comment = buffer_get_string(&e->request, NULL);
 523         if (k == NULL) {
 524                 free(comment);
 525                 goto send;
 526         }
 527         while (buffer_len(&e->request)) {
 528                 switch ((type = buffer_get_char(&e->request))) {
 529                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 530                         death = monotime() + buffer_get_int(&e->request);
 531                         break;
 532                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 533                         confirm = 1;
 534                         break;
 535                 default:
 536                         error("process_add_identity: "
 537                             "Unknown constraint type %d", type);
 538                         free(comment);
 539                         key_free(k);
 540                         goto send;
 541                 }
 542         }
 543         success = 1;
 544         if (lifetime && !death)
 545                 death = monotime() + lifetime;
 546         if ((id = lookup_identity(k, version)) == NULL) {
 547                 id = xcalloc(1, sizeof(Identity));
 548                 id->key = k;
 549                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 550                 /* Increment the number of identities. */
 551                 tab->nentries++;
 552         } else {
 553                 key_free(k);
 554                 free(id->comment);
 555         }
 556         id->comment = comment;
 557         id->death = death;
 558         id->confirm = confirm;
 559 send:
 560         buffer_put_int(&e->output, 1);
 561         buffer_put_char(&e->output,
 562             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 563 }
 564
 565 /* XXX todo: encrypt sensitive data with passphrase */
 566 static void
 567 process_lock_agent(SocketEntry *e, int lock)
 568 {
 569         int success = 0;
 570         char *passwd;
 571
 572         passwd = buffer_get_string(&e->request, NULL);
 573         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 574                 locked = 0;
 575                 memset(lock_passwd, 0, strlen(lock_passwd));
 576                 free(lock_passwd);
 577                 lock_passwd = NULL;
 578                 success = 1;
 579         } else if (!locked && lock) {
 580                 locked = 1;
 581                 lock_passwd = xstrdup(passwd);
 582                 success = 1;
 583         }
 584         memset(passwd, 0, strlen(passwd));
 585         free(passwd);
 586
 587         buffer_put_int(&e->output, 1);
 588         buffer_put_char(&e->output,
 589             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 590 }
 591
 592 static void
 593 no_identities(SocketEntry *e, u_int type)
 594 {
 595         Buffer msg;
 596
 597         buffer_init(&msg);
 598         buffer_put_char(&msg,
 599             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 600             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 601         buffer_put_int(&msg, 0);
 602         buffer_put_int(&e->output, buffer_len(&msg));
 603         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 604         buffer_free(&msg);
 605 }
 606
 607 #ifdef ENABLE_PKCS11
 608 static void
 609 process_add_smartcard_key(SocketEntry *e)
 610 {
 611         char *provider = NULL, *pin;
 612         int i, type, version, count = 0, success = 0, confirm = 0;
 613         time_t death = 0;
 614         Key **keys = NULL, *k;
 615         Identity *id;
 616         Idtab *tab;
 617
 618         provider = buffer_get_string(&e->request, NULL);
 619         pin = buffer_get_string(&e->request, NULL);
 620
 621         while (buffer_len(&e->request)) {
 622                 switch ((type = buffer_get_char(&e->request))) {
 623                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 624                         death = monotime() + buffer_get_int(&e->request);
 625                         break;
 626                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 627                         confirm = 1;
 628                         break;
 629                 default:
 630                         error("process_add_smartcard_key: "
 631                             "Unknown constraint type %d", type);
 632                         goto send;
 633                 }
 634         }
 635         if (lifetime && !death)
 636                 death = monotime() + lifetime;
 637
 638         count = pkcs11_add_provider(provider, pin, &keys);
 639         for (i = 0; i < count; i++) {
 640                 k = keys[i];
 641                 version = k->type == KEY_RSA1 ? 1 : 2;
 642                 tab = idtab_lookup(version);
 643                 if (lookup_identity(k, version) == NULL) {
 644                         id = xcalloc(1, sizeof(Identity));
 645                         id->key = k;
 646                         id->provider = xstrdup(provider);
 647                         id->comment = xstrdup(provider); /* XXX */
 648                         id->death = death;
 649                         id->confirm = confirm;
 650                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 651                         tab->nentries++;
 652                         success = 1;
 653                 } else {
 654                         key_free(k);
 655                 }
 656                 keys[i] = NULL;
 657         }
 658 send:
 659         free(pin);
 660         free(provider);
 661         free(keys);
 662         buffer_put_int(&e->output, 1);
 663         buffer_put_char(&e->output,
 664             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 665 }
 666
 667 static void
 668 process_remove_smartcard_key(SocketEntry *e)
 669 {
 670         char *provider = NULL, *pin = NULL;
 671         int version, success = 0;
 672         Identity *id, *nxt;
 673         Idtab *tab;
 674
 675         provider = buffer_get_string(&e->request, NULL);
 676         pin = buffer_get_string(&e->request, NULL);
 677         free(pin);
 678
 679         for (version = 1; version < 3; version++) {
 680                 tab = idtab_lookup(version);
 681                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 682                         nxt = TAILQ_NEXT(id, next);
 683                         /* Skip file--based keys */
 684                         if (id->provider == NULL)
 685                                 continue;
 686                         if (!strcmp(provider, id->provider)) {
 687                                 TAILQ_REMOVE(&tab->idlist, id, next);
 688                                 free_identity(id);
 689                                 tab->nentries--;
 690                         }
 691                 }
 692         }
 693         if (pkcs11_del_provider(provider) == 0)
 694                 success = 1;
 695         else
 696                 error("process_remove_smartcard_key:"
 697                     " pkcs11_del_provider failed");
 698         free(provider);
 699         buffer_put_int(&e->output, 1);
 700         buffer_put_char(&e->output,
 701             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 702 }
 703 #endif /* ENABLE_PKCS11 */
 704
 705 /* dispatch incoming messages */
 706
 707 static void
 708 process_message(SocketEntry *e)
 709 {
 710         u_int msg_len, type;
 711         u_char *cp;
 712
 713         if (buffer_len(&e->input) < 5)
 714                 return;         /* Incomplete message. */
 715         cp = buffer_ptr(&e->input);
 716         msg_len = get_u32(cp);
 717         if (msg_len > 256 * 1024) {
 718                 close_socket(e);
 719                 return;
 720         }
 721         if (buffer_len(&e->input) < msg_len + 4)
 722                 return;
 723
 724         /* move the current input to e->request */
 725         buffer_consume(&e->input, 4);
 726         buffer_clear(&e->request);
 727         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 728         buffer_consume(&e->input, msg_len);
 729         type = buffer_get_char(&e->request);
 730
 731         /* check wheter agent is locked */
 732         if (locked && type != SSH_AGENTC_UNLOCK) {
 733                 buffer_clear(&e->request);
 734                 switch (type) {
 735                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 736                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 737                         /* send empty lists */
 738                         no_identities(e, type);
 739                         break;
 740                 default:
 741                         /* send a fail message for all other request types */
 742                         buffer_put_int(&e->output, 1);
 743                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 744                 }
 745                 return;
 746         }
 747
 748         debug("type %d", type);
 749         switch (type) {
 750         case SSH_AGENTC_LOCK:
 751         case SSH_AGENTC_UNLOCK:
 752                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 753                 break;
 754         /* ssh1 */
 755         case SSH_AGENTC_RSA_CHALLENGE:
 756                 process_authentication_challenge1(e);
 757                 break;
 758         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 759                 process_request_identities(e, 1);
 760                 break;
 761         case SSH_AGENTC_ADD_RSA_IDENTITY:
 762         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 763                 process_add_identity(e, 1);
 764                 break;
 765         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 766                 process_remove_identity(e, 1);
 767                 break;
 768         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 769                 process_remove_all_identities(e, 1);
 770                 break;
 771         /* ssh2 */
 772         case SSH2_AGENTC_SIGN_REQUEST:
 773                 process_sign_request2(e);
 774                 break;
 775         case SSH2_AGENTC_REQUEST_IDENTITIES:
 776                 process_request_identities(e, 2);
 777                 break;
 778         case SSH2_AGENTC_ADD_IDENTITY:
 779         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 780                 process_add_identity(e, 2);
 781                 break;
 782         case SSH2_AGENTC_REMOVE_IDENTITY:
 783                 process_remove_identity(e, 2);
 784                 break;
 785         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 786                 process_remove_all_identities(e, 2);
 787                 break;
 788 #ifdef ENABLE_PKCS11
 789         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 790         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 791                 process_add_smartcard_key(e);
 792                 break;
 793         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 794                 process_remove_smartcard_key(e);
 795                 break;
 796 #endif /* ENABLE_PKCS11 */
 797         default:
 798                 /* Unknown message.  Respond with failure. */
 799                 error("Unknown message %d", type);
 800                 buffer_clear(&e->request);
 801                 buffer_put_int(&e->output, 1);
 802                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 803                 break;
 804         }
 805 }
 806
 807 static void
 808 new_socket(sock_type type, int fd)
 809 {
 810         u_int i, old_alloc, new_alloc;
 811
 812         if (type == AUTH_CONNECTION) {
 813                 debug("xcount %d -> %d", xcount, xcount + 1);
 814                 ++xcount;
 815         }
 816         set_nonblock(fd);
 817
 818         if (fd > max_fd)
 819                 max_fd = fd;
 820
 821         for (i = 0; i < sockets_alloc; i++)
 822                 if (sockets[i].type == AUTH_UNUSED) {
 823                         sockets[i].fd = fd;
 824                         buffer_init(&sockets[i].input);
 825                         buffer_init(&sockets[i].output);
 826                         buffer_init(&sockets[i].request);
 827                         sockets[i].type = type;
 828                         return;
 829                 }
 830         old_alloc = sockets_alloc;
 831         new_alloc = sockets_alloc + 10;
 832         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 833         for (i = old_alloc; i < new_alloc; i++)
 834                 sockets[i].type = AUTH_UNUSED;
 835         sockets_alloc = new_alloc;
 836         sockets[old_alloc].fd = fd;
 837         buffer_init(&sockets[old_alloc].input);
 838         buffer_init(&sockets[old_alloc].output);
 839         buffer_init(&sockets[old_alloc].request);
 840         sockets[old_alloc].type = type;
 841 }
 842
 843 static int
 844 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
 845     struct timeval **tvpp)
 846 {
 847         u_int i, sz;
 848         int n = 0;
 849         static struct timeval tv;
 850         time_t deadline;
 851
 852         for (i = 0; i < sockets_alloc; i++) {
 853                 switch (sockets[i].type) {
 854                 case AUTH_SOCKET:
 855                 case AUTH_CONNECTION:
 856                         n = MAX(n, sockets[i].fd);
 857                         break;
 858                 case AUTH_UNUSED:
 859                         break;
 860                 default:
 861                         fatal("Unknown socket type %d", sockets[i].type);
 862                         break;
 863                 }
 864         }
 865
 866         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 867         if (*fdrp == NULL || sz > *nallocp) {
 868                 free(*fdrp);
 869                 free(*fdwp);
 870                 *fdrp = xmalloc(sz);
 871                 *fdwp = xmalloc(sz);
 872                 *nallocp = sz;
 873         }
 874         if (n < *fdl)
 875                 debug("XXX shrink: %d < %d", n, *fdl);
 876         *fdl = n;
 877         memset(*fdrp, 0, sz);
 878         memset(*fdwp, 0, sz);
 879
 880         for (i = 0; i < sockets_alloc; i++) {
 881                 switch (sockets[i].type) {
 882                 case AUTH_SOCKET:
 883                 case AUTH_CONNECTION:
 884                         FD_SET(sockets[i].fd, *fdrp);
 885                         if (buffer_len(&sockets[i].output) > 0)
 886                                 FD_SET(sockets[i].fd, *fdwp);
 887                         break;
 888                 default:
 889                         break;
 890                 }
 891         }
 892         deadline = reaper();
 893         if (parent_alive_interval != 0)
 894                 deadline = (deadline == 0) ? parent_alive_interval :
 895                     MIN(deadline, parent_alive_interval);
 896         if (deadline == 0) {
 897                 *tvpp = NULL;
 898         } else {
 899                 tv.tv_sec = deadline;
 900                 tv.tv_usec = 0;
 901                 *tvpp = &tv;
 902         }
 903         return (1);
 904 }
 905
 906 static void
 907 after_select(fd_set *readset, fd_set *writeset)
 908 {
 909         struct sockaddr_un sunaddr;
 910         socklen_t slen;
 911         char buf[1024];
 912         int len, sock;
 913         u_int i, orig_alloc;
 914         uid_t euid;
 915         gid_t egid;
 916
 917         for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++)
 918                 switch (sockets[i].type) {
 919                 case AUTH_UNUSED:
 920                         break;
 921                 case AUTH_SOCKET:
 922                         if (FD_ISSET(sockets[i].fd, readset)) {
 923                                 slen = sizeof(sunaddr);
 924                                 sock = accept(sockets[i].fd,
 925                                     (struct sockaddr *)&sunaddr, &slen);
 926                                 if (sock < 0) {
 927                                         error("accept from AUTH_SOCKET: %s",
 928                                             strerror(errno));
 929                                         break;
 930                                 }
 931                                 if (getpeereid(sock, &euid, &egid) < 0) {
 932                                         error("getpeereid %d failed: %s",
 933                                             sock, strerror(errno));
 934                                         close(sock);
 935                                         break;
 936                                 }
 937                                 if ((euid != 0) && (getuid() != euid)) {
 938                                         error("uid mismatch: "
 939                                             "peer euid %u != uid %u",
 940                                             (u_int) euid, (u_int) getuid());
 941                                         close(sock);
 942                                         break;
 943                                 }
 944                                 new_socket(AUTH_CONNECTION, sock);
 945                         }
 946                         break;
 947                 case AUTH_CONNECTION:
 948                         if (buffer_len(&sockets[i].output) > 0 &&
 949                             FD_ISSET(sockets[i].fd, writeset)) {
 950                                 len = write(sockets[i].fd,
 951                                     buffer_ptr(&sockets[i].output),
 952                                     buffer_len(&sockets[i].output));
 953                                 if (len == -1 && (errno == EAGAIN ||
 954                                     errno == EWOULDBLOCK ||
 955                                     errno == EINTR))
 956                                         continue;
 957                                 if (len <= 0) {
 958                                         close_socket(&sockets[i]);
 959                                         break;
 960                                 }
 961                                 buffer_consume(&sockets[i].output, len);
 962                         }
 963                         if (FD_ISSET(sockets[i].fd, readset)) {
 964                                 len = read(sockets[i].fd, buf, sizeof(buf));
 965                                 if (len == -1 && (errno == EAGAIN ||
 966                                     errno == EWOULDBLOCK ||
 967                                     errno == EINTR))
 968                                         continue;
 969                                 if (len <= 0) {
 970                                         close_socket(&sockets[i]);
 971                                         break;
 972                                 }
 973                                 buffer_append(&sockets[i].input, buf, len);
 974                                 process_message(&sockets[i]);
 975                         }
 976                         break;
 977                 default:
 978                         fatal("Unknown type %d", sockets[i].type);
 979                 }
 980 }
 981
 982 static void
 983 cleanup_socket(void)
 984 {
 985         if (socket_name[0])
 986                 unlink(socket_name);
 987         if (socket_dir[0])
 988                 rmdir(socket_dir);
 989 }
 990
 991 void
 992 cleanup_exit(int i)
 993 {
 994         cleanup_socket();
 995         _exit(i);
 996 }
 997
 998 /*ARGSUSED*/
 999 static void
1000 cleanup_handler(int sig)
1001 {
1002         cleanup_socket();
1003 #ifdef ENABLE_PKCS11
1004         pkcs11_terminate();
1005 #endif
1006         _exit(2);
1007 }
1008
1009 static void
1010 check_parent_exists(void)
1011 {
1012         /*
1013          * If our parent has exited then getppid() will return (pid_t)1,
1014          * so testing for that should be safe.
1015          */
1016         if (parent_pid != -1 && getppid() != parent_pid) {
1017                 /* printf("Parent has died - Authentication agent exiting.\n"); */
1018                 cleanup_socket();
1019                 _exit(2);
1020         }
1021 }
1022
1023 static void
1024 usage(void)
1025 {
1026         fprintf(stderr, "usage: %s [options] [command [arg ...]]\n",
1027             __progname);
1028         fprintf(stderr, "Options:\n");
1029         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1030         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1031         fprintf(stderr, "  -k          Kill the current agent.\n");
1032         fprintf(stderr, "  -d          Debug mode.\n");
1033         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1034         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1035         fprintf(stderr, "  -x          Exit when the last client disconnects.\n");
1036         exit(1);
1037 }
1038
1039 int
1040 main(int ac, char **av)
1041 {
1042         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1043         int sock, fd, ch, result, saved_errno;
1044         u_int nalloc;
1045         char *shell, *format, *pidstr, *agentsocket = NULL;
1046         fd_set *readsetp = NULL, *writesetp = NULL;
1047         struct sockaddr_un sunaddr;
1048 #ifdef HAVE_SETRLIMIT
1049         struct rlimit rlim;
1050 #endif
1051         int prev_mask;
1052         extern int optind;
1053         extern char *optarg;
1054         pid_t pid;
1055         char pidstrbuf[1 + 3 * sizeof pid];
1056         struct timeval *tvp = NULL;
1057         size_t len;
1058
1059         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1060         sanitise_stdfd();
1061
1062         /* drop */
1063         setegid(getgid());
1064         setgid(getgid());
1065         setuid(geteuid());
1066
1067 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1068         /* Disable ptrace on Linux without sgid bit */
1069         prctl(PR_SET_DUMPABLE, 0);
1070 #endif
1071
1072         OpenSSL_add_all_algorithms();
1073
1074         __progname = ssh_get_progname(av[0]);
1075         seed_rng();
1076
1077         while ((ch = getopt(ac, av, "cdksa:t:x")) != -1) {
1078                 switch (ch) {
1079                 case 'c':
1080                         if (s_flag)
1081                                 usage();
1082                         c_flag++;
1083                         break;
1084                 case 'k':
1085                         k_flag++;
1086                         break;
1087                 case 's':
1088                         if (c_flag)
1089                                 usage();
1090                         s_flag++;
1091                         break;
1092                 case 'd':
1093                         if (d_flag)
1094                                 usage();
1095                         d_flag++;
1096                         break;
1097                 case 'a':
1098                         agentsocket = optarg;
1099                         break;
1100                 case 't':
1101                         if ((lifetime = convtime(optarg)) == -1) {
1102                                 fprintf(stderr, "Invalid lifetime\n");
1103                                 usage();
1104                         }
1105                         break;
1106                 case 'x':
1107                         xcount = 0;
1108                         break;
1109                 default:
1110                         usage();
1111                 }
1112         }
1113         ac -= optind;
1114         av += optind;
1115
1116         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1117                 usage();
1118
1119         if (ac == 0 && !c_flag && !s_flag) {
1120                 shell = getenv("SHELL");
1121                 if (shell != NULL && (len = strlen(shell)) > 2 &&
1122                     strncmp(shell + len - 3, "csh", 3) == 0)
1123                         c_flag = 1;
1124         }
1125         if (k_flag) {
1126                 const char *errstr = NULL;
1127
1128                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1129                 if (pidstr == NULL) {
1130                         fprintf(stderr, "%s not set, cannot kill agent\n",
1131                             SSH_AGENTPID_ENV_NAME);
1132                         exit(1);
1133                 }
1134                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1135                 if (errstr) {
1136                         fprintf(stderr,
1137                             "%s=\"%s\", which is not a good PID: %s\n",
1138                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1139                         exit(1);
1140                 }
1141                 if (kill(pid, SIGTERM) == -1) {
1142                         perror("kill");
1143                         exit(1);
1144                 }
1145                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1146                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1147                 printf(format, SSH_AGENTPID_ENV_NAME);
1148                 printf("echo Agent pid %ld killed;\n", (long)pid);
1149                 exit(0);
1150         }
1151         parent_pid = getpid();
1152
1153         if (agentsocket == NULL) {
1154                 /* Create private directory for agent socket */
1155                 mktemp_proto(socket_dir, sizeof(socket_dir));
1156                 if (mkdtemp(socket_dir) == NULL) {
1157                         perror("mkdtemp: private socket dir");
1158                         exit(1);
1159                 }
1160                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1161                     (long)parent_pid);
1162         } else {
1163                 /* Try to use specified agent socket */
1164                 socket_dir[0] = '\0';
1165                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1166         }
1167
1168         /*
1169          * Create socket early so it will exist before command gets run from
1170          * the parent.
1171          */
1172         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1173         if (sock < 0) {
1174                 perror("socket");
1175                 *socket_name = '\0'; /* Don't unlink any existing file */
1176                 cleanup_exit(1);
1177         }
1178         memset(&sunaddr, 0, sizeof(sunaddr));
1179         sunaddr.sun_family = AF_UNIX;
1180         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1181         prev_mask = umask(0177);
1182         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1183                 perror("bind");
1184                 *socket_name = '\0'; /* Don't unlink any existing file */
1185                 umask(prev_mask);
1186                 cleanup_exit(1);
1187         }
1188         umask(prev_mask);
1189         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1190                 perror("listen");
1191                 cleanup_exit(1);
1192         }
1193
1194         /*
1195          * Fork, and have the parent execute the command, if any, or present
1196          * the socket data.  The child continues as the authentication agent.
1197          */
1198         if (d_flag) {
1199                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1200                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1201                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1202                     SSH_AUTHSOCKET_ENV_NAME);
1203                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1204                 goto skip;
1205         }
1206         pid = fork();
1207         if (pid == -1) {
1208                 perror("fork");
1209                 cleanup_exit(1);
1210         }
1211         if (pid != 0) {         /* Parent - execute the given command. */
1212                 close(sock);
1213                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1214                 if (ac == 0) {
1215                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1216                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1217                             SSH_AUTHSOCKET_ENV_NAME);
1218                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1219                             SSH_AGENTPID_ENV_NAME);
1220                         printf("echo Agent pid %ld;\n", (long)pid);
1221                         exit(0);
1222                 }
1223                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1224                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1225                         perror("setenv");
1226                         exit(1);
1227                 }
1228                 execvp(av[0], av);
1229                 perror(av[0]);
1230                 exit(1);
1231         }
1232         /* child */
1233         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1234
1235         if (setsid() == -1) {
1236                 error("setsid: %s", strerror(errno));
1237                 cleanup_exit(1);
1238         }
1239
1240         (void)chdir("/");
1241         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1242                 /* XXX might close listen socket */
1243                 (void)dup2(fd, STDIN_FILENO);
1244                 (void)dup2(fd, STDOUT_FILENO);
1245                 (void)dup2(fd, STDERR_FILENO);
1246                 if (fd > 2)
1247                         close(fd);
1248         }
1249
1250 #ifdef HAVE_SETRLIMIT
1251         /* deny core dumps, since memory contains unencrypted private keys */
1252         rlim.rlim_cur = rlim.rlim_max = 0;
1253         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1254                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1255                 cleanup_exit(1);
1256         }
1257 #endif
1258
1259 skip:
1260
1261 #ifdef ENABLE_PKCS11
1262         pkcs11_init(0);
1263 #endif
1264         new_socket(AUTH_SOCKET, sock);
1265         if (ac > 0)
1266                 parent_alive_interval = 10;
1267         idtab_init();
1268         signal(SIGPIPE, SIG_IGN);
1269         signal(SIGINT, d_flag ? cleanup_handler : SIG_IGN);
1270         signal(SIGHUP, cleanup_handler);
1271         signal(SIGTERM, cleanup_handler);
1272         nalloc = 0;
1273
1274         while (1) {
1275                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1276                 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1277                 saved_errno = errno;
1278                 if (parent_alive_interval != 0)
1279                         check_parent_exists();
1280                 (void) reaper();        /* remove expired keys */
1281                 if (result < 0) {
1282                         if (saved_errno == EINTR)
1283                                 continue;
1284                         fatal("select: %s", strerror(saved_errno));
1285                 } else if (result > 0)
1286                         after_select(readsetp, writesetp);
1287         }
1288         /* NOTREACHED */
1289 }