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
  39 #include <sys/types.h>
  40 #include <sys/param.h>
  41 #include <sys/resource.h>
  42 #include <sys/stat.h>
  43 #include <sys/socket.h>
  44 #ifdef HAVE_SYS_TIME_H
  45 # include <sys/time.h>
  46 #endif
  47 #ifdef HAVE_SYS_UN_H
  48 # include <sys/un.h>
  49 #endif
  50 #include "openbsd-compat/sys-queue.h"
  51
  52 #include <openssl/evp.h>
  53 #include <openssl/md5.h>
  54 #include "openbsd-compat/openssl-compat.h"
  55
  56 #include <errno.h>
  57 #include <fcntl.h>
  58 #ifdef HAVE_PATHS_H
  59 # include <paths.h>
  60 #endif
  61 #include <signal.h>
  62 #include <stdarg.h>
  63 #include <stdio.h>
  64 #include <stdlib.h>
  65 #include <time.h>
  66 #include <string.h>
  67 #include <unistd.h>
  68
  69 #include "xmalloc.h"
  70 #include "ssh.h"
  71 #include "rsa.h"
  72 #include "buffer.h"
  73 #include "key.h"
  74 #include "authfd.h"
  75 #include "compat.h"
  76 #include "log.h"
  77 #include "misc.h"
  78
  79 #ifdef ENABLE_PKCS11
  80 #include "ssh-pkcs11.h"
  81 #endif
  82
  83 #if defined(HAVE_SYS_PRCTL_H)
  84 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  85 #endif
  86
  87 typedef enum {
  88         AUTH_UNUSED,
  89         AUTH_SOCKET,
  90         AUTH_CONNECTION
  91 } sock_type;
  92
  93 typedef struct {
  94         int fd;
  95         sock_type type;
  96         Buffer input;
  97         Buffer output;
  98         Buffer request;
  99 } SocketEntry;
 100
 101 u_int sockets_alloc = 0;
 102 SocketEntry *sockets = NULL;
 103
 104 typedef struct identity {
 105         TAILQ_ENTRY(identity) next;
 106         Key *key;
 107         char *comment;
 108         char *provider;
 109         time_t 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 time_t 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 in seconds (0 == forever) */
 138 static long 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         free(id->provider);
 176         free(id->comment);
 177         free(id);
 178 }
 179
 180 /* return matching private key for given public key */
 181 static Identity *
 182 lookup_identity(Key *key, int version)
 183 {
 184         Identity *id;
 185
 186         Idtab *tab = idtab_lookup(version);
 187         TAILQ_FOREACH(id, &tab->idlist, next) {
 188                 if (key_equal(key, id->key))
 189                         return (id);
 190         }
 191         return (NULL);
 192 }
 193
 194 /* Check confirmation of keysign request */
 195 static int
 196 confirm_key(Identity *id)
 197 {
 198         char *p;
 199         int ret = -1;
 200
 201         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 202         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 203             id->comment, p))
 204                 ret = 0;
 205         free(p);
 206
 207         return (ret);
 208 }
 209
 210 /* send list of supported public keys to 'client' */
 211 static void
 212 process_request_identities(SocketEntry *e, int version)
 213 {
 214         Idtab *tab = idtab_lookup(version);
 215         Identity *id;
 216         Buffer msg;
 217
 218         buffer_init(&msg);
 219         buffer_put_char(&msg, (version == 1) ?
 220             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 221         buffer_put_int(&msg, tab->nentries);
 222         TAILQ_FOREACH(id, &tab->idlist, next) {
 223                 if (id->key->type == KEY_RSA1) {
 224                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 225                         buffer_put_bignum(&msg, id->key->rsa->e);
 226                         buffer_put_bignum(&msg, id->key->rsa->n);
 227                 } else {
 228                         u_char *blob;
 229                         u_int blen;
 230                         key_to_blob(id->key, &blob, &blen);
 231                         buffer_put_string(&msg, blob, blen);
 232                         free(blob);
 233                 }
 234                 buffer_put_cstring(&msg, id->comment);
 235         }
 236         buffer_put_int(&e->output, buffer_len(&msg));
 237         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 238         buffer_free(&msg);
 239 }
 240
 241 /* ssh1 only */
 242 static void
 243 process_authentication_challenge1(SocketEntry *e)
 244 {
 245         u_char buf[32], mdbuf[16], session_id[16];
 246         u_int response_type;
 247         BIGNUM *challenge;
 248         Identity *id;
 249         int i, len;
 250         Buffer msg;
 251         MD5_CTX md;
 252         Key *key;
 253
 254         buffer_init(&msg);
 255         key = key_new(KEY_RSA1);
 256         if ((challenge = BN_new()) == NULL)
 257                 fatal("process_authentication_challenge1: BN_new failed");
 258
 259         (void) buffer_get_int(&e->request);                     /* ignored */
 260         buffer_get_bignum(&e->request, key->rsa->e);
 261         buffer_get_bignum(&e->request, key->rsa->n);
 262         buffer_get_bignum(&e->request, challenge);
 263
 264         /* Only protocol 1.1 is supported */
 265         if (buffer_len(&e->request) == 0)
 266                 goto failure;
 267         buffer_get(&e->request, session_id, 16);
 268         response_type = buffer_get_int(&e->request);
 269         if (response_type != 1)
 270                 goto failure;
 271
 272         id = lookup_identity(key, 1);
 273         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 274                 Key *private = id->key;
 275                 /* Decrypt the challenge using the private key. */
 276                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 277                         goto failure;
 278
 279                 /* The response is MD5 of decrypted challenge plus session id. */
 280                 len = BN_num_bytes(challenge);
 281                 if (len <= 0 || len > 32) {
 282                         logit("process_authentication_challenge: bad challenge length %d", len);
 283                         goto failure;
 284                 }
 285                 memset(buf, 0, 32);
 286                 BN_bn2bin(challenge, buf + 32 - len);
 287                 MD5_Init(&md);
 288                 MD5_Update(&md, buf, 32);
 289                 MD5_Update(&md, session_id, 16);
 290                 MD5_Final(mdbuf, &md);
 291
 292                 /* Send the response. */
 293                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 294                 for (i = 0; i < 16; i++)
 295                         buffer_put_char(&msg, mdbuf[i]);
 296                 goto send;
 297         }
 298
 299 failure:
 300         /* Unknown identity or protocol error.  Send failure. */
 301         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 302 send:
 303         buffer_put_int(&e->output, buffer_len(&msg));
 304         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 305         key_free(key);
 306         BN_clear_free(challenge);
 307         buffer_free(&msg);
 308 }
 309
 310 /* ssh2 only */
 311 static void
 312 process_sign_request2(SocketEntry *e)
 313 {
 314         u_char *blob, *data, *signature = NULL;
 315         u_int blen, dlen, slen = 0;
 316         extern int datafellows;
 317         int odatafellows;
 318         int ok = -1, flags;
 319         Buffer msg;
 320         Key *key;
 321
 322         datafellows = 0;
 323
 324         blob = buffer_get_string(&e->request, &blen);
 325         data = buffer_get_string(&e->request, &dlen);
 326
 327         flags = buffer_get_int(&e->request);
 328         odatafellows = datafellows;
 329         if (flags & SSH_AGENT_OLD_SIGNATURE)
 330                 datafellows = SSH_BUG_SIGBLOB;
 331
 332         key = key_from_blob(blob, blen);
 333         if (key != NULL) {
 334                 Identity *id = lookup_identity(key, 2);
 335                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 336                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 337                 key_free(key);
 338         }
 339         buffer_init(&msg);
 340         if (ok == 0) {
 341                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 342                 buffer_put_string(&msg, signature, slen);
 343         } else {
 344                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 345         }
 346         buffer_put_int(&e->output, buffer_len(&msg));
 347         buffer_append(&e->output, buffer_ptr(&msg),
 348             buffer_len(&msg));
 349         buffer_free(&msg);
 350         free(data);
 351         free(blob);
 352         free(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                 free(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 time_t
 432 reaper(void)
 433 {
 434         time_t deadline = 0, now = monotime();
 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, confirm = 0;
 467         char *comment;
 468         time_t death = 0;
 469         Key *k = NULL;
 470
 471         switch (version) {
 472         case 1:
 473                 k = key_new_private(KEY_RSA1);
 474                 (void) buffer_get_int(&e->request);             /* ignored */
 475                 buffer_get_bignum(&e->request, k->rsa->n);
 476                 buffer_get_bignum(&e->request, k->rsa->e);
 477                 buffer_get_bignum(&e->request, k->rsa->d);
 478                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 479
 480                 /* SSH and SSL have p and q swapped */
 481                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 482                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 483
 484                 /* Generate additional parameters */
 485                 rsa_generate_additional_parameters(k->rsa);
 486
 487                 /* enable blinding */
 488                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 489                         error("process_add_identity: RSA_blinding_on failed");
 490                         key_free(k);
 491                         goto send;
 492                 }
 493                 break;
 494         case 2:
 495                 k = key_private_deserialize(&e->request);
 496                 if (k == NULL) {
 497                         buffer_clear(&e->request);
 498                         goto send;
 499                 }
 500                 break;
 501         }
 502         comment = buffer_get_string(&e->request, NULL);
 503         if (k == NULL) {
 504                 free(comment);
 505                 goto send;
 506         }
 507         while (buffer_len(&e->request)) {
 508                 switch ((type = buffer_get_char(&e->request))) {
 509                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 510                         death = monotime() + buffer_get_int(&e->request);
 511                         break;
 512                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 513                         confirm = 1;
 514                         break;
 515                 default:
 516                         error("process_add_identity: "
 517                             "Unknown constraint type %d", type);
 518                         free(comment);
 519                         key_free(k);
 520                         goto send;
 521                 }
 522         }
 523         success = 1;
 524         if (lifetime && !death)
 525                 death = monotime() + lifetime;
 526         if ((id = lookup_identity(k, version)) == NULL) {
 527                 id = xcalloc(1, sizeof(Identity));
 528                 id->key = k;
 529                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 530                 /* Increment the number of identities. */
 531                 tab->nentries++;
 532         } else {
 533                 key_free(k);
 534                 free(id->comment);
 535         }
 536         id->comment = comment;
 537         id->death = death;
 538         id->confirm = confirm;
 539 send:
 540         buffer_put_int(&e->output, 1);
 541         buffer_put_char(&e->output,
 542             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 543 }
 544
 545 /* XXX todo: encrypt sensitive data with passphrase */
 546 static void
 547 process_lock_agent(SocketEntry *e, int lock)
 548 {
 549         int success = 0;
 550         char *passwd;
 551
 552         passwd = buffer_get_string(&e->request, NULL);
 553         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 554                 locked = 0;
 555                 memset(lock_passwd, 0, strlen(lock_passwd));
 556                 free(lock_passwd);
 557                 lock_passwd = NULL;
 558                 success = 1;
 559         } else if (!locked && lock) {
 560                 locked = 1;
 561                 lock_passwd = xstrdup(passwd);
 562                 success = 1;
 563         }
 564         memset(passwd, 0, strlen(passwd));
 565         free(passwd);
 566
 567         buffer_put_int(&e->output, 1);
 568         buffer_put_char(&e->output,
 569             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 570 }
 571
 572 static void
 573 no_identities(SocketEntry *e, u_int type)
 574 {
 575         Buffer msg;
 576
 577         buffer_init(&msg);
 578         buffer_put_char(&msg,
 579             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 580             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 581         buffer_put_int(&msg, 0);
 582         buffer_put_int(&e->output, buffer_len(&msg));
 583         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 584         buffer_free(&msg);
 585 }
 586
 587 #ifdef ENABLE_PKCS11
 588 static void
 589 process_add_smartcard_key(SocketEntry *e)
 590 {
 591         char *provider = NULL, *pin;
 592         int i, type, version, count = 0, success = 0, confirm = 0;
 593         time_t death = 0;
 594         Key **keys = NULL, *k;
 595         Identity *id;
 596         Idtab *tab;
 597
 598         provider = buffer_get_string(&e->request, NULL);
 599         pin = buffer_get_string(&e->request, NULL);
 600
 601         while (buffer_len(&e->request)) {
 602                 switch ((type = buffer_get_char(&e->request))) {
 603                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 604                         death = monotime() + buffer_get_int(&e->request);
 605                         break;
 606                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 607                         confirm = 1;
 608                         break;
 609                 default:
 610                         error("process_add_smartcard_key: "
 611                             "Unknown constraint type %d", type);
 612                         goto send;
 613                 }
 614         }
 615         if (lifetime && !death)
 616                 death = monotime() + lifetime;
 617
 618         count = pkcs11_add_provider(provider, pin, &keys);
 619         for (i = 0; i < count; i++) {
 620                 k = keys[i];
 621                 version = k->type == KEY_RSA1 ? 1 : 2;
 622                 tab = idtab_lookup(version);
 623                 if (lookup_identity(k, version) == NULL) {
 624                         id = xcalloc(1, sizeof(Identity));
 625                         id->key = k;
 626                         id->provider = xstrdup(provider);
 627                         id->comment = xstrdup(provider); /* XXX */
 628                         id->death = death;
 629                         id->confirm = confirm;
 630                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 631                         tab->nentries++;
 632                         success = 1;
 633                 } else {
 634                         key_free(k);
 635                 }
 636                 keys[i] = NULL;
 637         }
 638 send:
 639         free(pin);
 640         free(provider);
 641         free(keys);
 642         buffer_put_int(&e->output, 1);
 643         buffer_put_char(&e->output,
 644             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 645 }
 646
 647 static void
 648 process_remove_smartcard_key(SocketEntry *e)
 649 {
 650         char *provider = NULL, *pin = NULL;
 651         int version, success = 0;
 652         Identity *id, *nxt;
 653         Idtab *tab;
 654
 655         provider = buffer_get_string(&e->request, NULL);
 656         pin = buffer_get_string(&e->request, NULL);
 657         free(pin);
 658
 659         for (version = 1; version < 3; version++) {
 660                 tab = idtab_lookup(version);
 661                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 662                         nxt = TAILQ_NEXT(id, next);
 663                         /* Skip file--based keys */
 664                         if (id->provider == NULL)
 665                                 continue;
 666                         if (!strcmp(provider, id->provider)) {
 667                                 TAILQ_REMOVE(&tab->idlist, id, next);
 668                                 free_identity(id);
 669                                 tab->nentries--;
 670                         }
 671                 }
 672         }
 673         if (pkcs11_del_provider(provider) == 0)
 674                 success = 1;
 675         else
 676                 error("process_remove_smartcard_key:"
 677                     " pkcs11_del_provider failed");
 678         free(provider);
 679         buffer_put_int(&e->output, 1);
 680         buffer_put_char(&e->output,
 681             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 682 }
 683 #endif /* ENABLE_PKCS11 */
 684
 685 /* dispatch incoming messages */
 686
 687 static void
 688 process_message(SocketEntry *e)
 689 {
 690         u_int msg_len, type;
 691         u_char *cp;
 692
 693         if (buffer_len(&e->input) < 5)
 694                 return;         /* Incomplete message. */
 695         cp = buffer_ptr(&e->input);
 696         msg_len = get_u32(cp);
 697         if (msg_len > 256 * 1024) {
 698                 close_socket(e);
 699                 return;
 700         }
 701         if (buffer_len(&e->input) < msg_len + 4)
 702                 return;
 703
 704         /* move the current input to e->request */
 705         buffer_consume(&e->input, 4);
 706         buffer_clear(&e->request);
 707         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 708         buffer_consume(&e->input, msg_len);
 709         type = buffer_get_char(&e->request);
 710
 711         /* check wheter agent is locked */
 712         if (locked && type != SSH_AGENTC_UNLOCK) {
 713                 buffer_clear(&e->request);
 714                 switch (type) {
 715                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 716                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 717                         /* send empty lists */
 718                         no_identities(e, type);
 719                         break;
 720                 default:
 721                         /* send a fail message for all other request types */
 722                         buffer_put_int(&e->output, 1);
 723                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 724                 }
 725                 return;
 726         }
 727
 728         debug("type %d", type);
 729         switch (type) {
 730         case SSH_AGENTC_LOCK:
 731         case SSH_AGENTC_UNLOCK:
 732                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 733                 break;
 734         /* ssh1 */
 735         case SSH_AGENTC_RSA_CHALLENGE:
 736                 process_authentication_challenge1(e);
 737                 break;
 738         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 739                 process_request_identities(e, 1);
 740                 break;
 741         case SSH_AGENTC_ADD_RSA_IDENTITY:
 742         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 743                 process_add_identity(e, 1);
 744                 break;
 745         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 746                 process_remove_identity(e, 1);
 747                 break;
 748         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 749                 process_remove_all_identities(e, 1);
 750                 break;
 751         /* ssh2 */
 752         case SSH2_AGENTC_SIGN_REQUEST:
 753                 process_sign_request2(e);
 754                 break;
 755         case SSH2_AGENTC_REQUEST_IDENTITIES:
 756                 process_request_identities(e, 2);
 757                 break;
 758         case SSH2_AGENTC_ADD_IDENTITY:
 759         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 760                 process_add_identity(e, 2);
 761                 break;
 762         case SSH2_AGENTC_REMOVE_IDENTITY:
 763                 process_remove_identity(e, 2);
 764                 break;
 765         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 766                 process_remove_all_identities(e, 2);
 767                 break;
 768 #ifdef ENABLE_PKCS11
 769         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 770         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 771                 process_add_smartcard_key(e);
 772                 break;
 773         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 774                 process_remove_smartcard_key(e);
 775                 break;
 776 #endif /* ENABLE_PKCS11 */
 777         default:
 778                 /* Unknown message.  Respond with failure. */
 779                 error("Unknown message %d", type);
 780                 buffer_clear(&e->request);
 781                 buffer_put_int(&e->output, 1);
 782                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 783                 break;
 784         }
 785 }
 786
 787 static void
 788 new_socket(sock_type type, int fd)
 789 {
 790         u_int i, old_alloc, new_alloc;
 791
 792         set_nonblock(fd);
 793
 794         if (fd > max_fd)
 795                 max_fd = fd;
 796
 797         for (i = 0; i < sockets_alloc; i++)
 798                 if (sockets[i].type == AUTH_UNUSED) {
 799                         sockets[i].fd = fd;
 800                         buffer_init(&sockets[i].input);
 801                         buffer_init(&sockets[i].output);
 802                         buffer_init(&sockets[i].request);
 803                         sockets[i].type = type;
 804                         return;
 805                 }
 806         old_alloc = sockets_alloc;
 807         new_alloc = sockets_alloc + 10;
 808         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 809         for (i = old_alloc; i < new_alloc; i++)
 810                 sockets[i].type = AUTH_UNUSED;
 811         sockets_alloc = new_alloc;
 812         sockets[old_alloc].fd = fd;
 813         buffer_init(&sockets[old_alloc].input);
 814         buffer_init(&sockets[old_alloc].output);
 815         buffer_init(&sockets[old_alloc].request);
 816         sockets[old_alloc].type = type;
 817 }
 818
 819 static int
 820 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
 821     struct timeval **tvpp)
 822 {
 823         u_int i, sz;
 824         int n = 0;
 825         static struct timeval tv;
 826         time_t deadline;
 827
 828         for (i = 0; i < sockets_alloc; i++) {
 829                 switch (sockets[i].type) {
 830                 case AUTH_SOCKET:
 831                 case AUTH_CONNECTION:
 832                         n = MAX(n, sockets[i].fd);
 833                         break;
 834                 case AUTH_UNUSED:
 835                         break;
 836                 default:
 837                         fatal("Unknown socket type %d", sockets[i].type);
 838                         break;
 839                 }
 840         }
 841
 842         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 843         if (*fdrp == NULL || sz > *nallocp) {
 844                 free(*fdrp);
 845                 free(*fdwp);
 846                 *fdrp = xmalloc(sz);
 847                 *fdwp = xmalloc(sz);
 848                 *nallocp = sz;
 849         }
 850         if (n < *fdl)
 851                 debug("XXX shrink: %d < %d", n, *fdl);
 852         *fdl = n;
 853         memset(*fdrp, 0, sz);
 854         memset(*fdwp, 0, sz);
 855
 856         for (i = 0; i < sockets_alloc; i++) {
 857                 switch (sockets[i].type) {
 858                 case AUTH_SOCKET:
 859                 case AUTH_CONNECTION:
 860                         FD_SET(sockets[i].fd, *fdrp);
 861                         if (buffer_len(&sockets[i].output) > 0)
 862                                 FD_SET(sockets[i].fd, *fdwp);
 863                         break;
 864                 default:
 865                         break;
 866                 }
 867         }
 868         deadline = reaper();
 869         if (parent_alive_interval != 0)
 870                 deadline = (deadline == 0) ? parent_alive_interval :
 871                     MIN(deadline, parent_alive_interval);
 872         if (deadline == 0) {
 873                 *tvpp = NULL;
 874         } else {
 875                 tv.tv_sec = deadline;
 876                 tv.tv_usec = 0;
 877                 *tvpp = &tv;
 878         }
 879         return (1);
 880 }
 881
 882 static void
 883 after_select(fd_set *readset, fd_set *writeset)
 884 {
 885         struct sockaddr_un sunaddr;
 886         socklen_t slen;
 887         char buf[1024];
 888         int len, sock;
 889         u_int i, orig_alloc;
 890         uid_t euid;
 891         gid_t egid;
 892
 893         for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++)
 894                 switch (sockets[i].type) {
 895                 case AUTH_UNUSED:
 896                         break;
 897                 case AUTH_SOCKET:
 898                         if (FD_ISSET(sockets[i].fd, readset)) {
 899                                 slen = sizeof(sunaddr);
 900                                 sock = accept(sockets[i].fd,
 901                                     (struct sockaddr *)&sunaddr, &slen);
 902                                 if (sock < 0) {
 903                                         error("accept from AUTH_SOCKET: %s",
 904                                             strerror(errno));
 905                                         break;
 906                                 }
 907                                 if (getpeereid(sock, &euid, &egid) < 0) {
 908                                         error("getpeereid %d failed: %s",
 909                                             sock, strerror(errno));
 910                                         close(sock);
 911                                         break;
 912                                 }
 913                                 if ((euid != 0) && (getuid() != euid)) {
 914                                         error("uid mismatch: "
 915                                             "peer euid %u != uid %u",
 916                                             (u_int) euid, (u_int) getuid());
 917                                         close(sock);
 918                                         break;
 919                                 }
 920                                 new_socket(AUTH_CONNECTION, sock);
 921                         }
 922                         break;
 923                 case AUTH_CONNECTION:
 924                         if (buffer_len(&sockets[i].output) > 0 &&
 925                             FD_ISSET(sockets[i].fd, writeset)) {
 926                                 len = write(sockets[i].fd,
 927                                     buffer_ptr(&sockets[i].output),
 928                                     buffer_len(&sockets[i].output));
 929                                 if (len == -1 && (errno == EAGAIN ||
 930                                     errno == EWOULDBLOCK ||
 931                                     errno == EINTR))
 932                                         continue;
 933                                 if (len <= 0) {
 934                                         close_socket(&sockets[i]);
 935                                         break;
 936                                 }
 937                                 buffer_consume(&sockets[i].output, len);
 938                         }
 939                         if (FD_ISSET(sockets[i].fd, readset)) {
 940                                 len = read(sockets[i].fd, buf, sizeof(buf));
 941                                 if (len == -1 && (errno == EAGAIN ||
 942                                     errno == EWOULDBLOCK ||
 943                                     errno == EINTR))
 944                                         continue;
 945                                 if (len <= 0) {
 946                                         close_socket(&sockets[i]);
 947                                         break;
 948                                 }
 949                                 buffer_append(&sockets[i].input, buf, len);
 950                                 process_message(&sockets[i]);
 951                         }
 952                         break;
 953                 default:
 954                         fatal("Unknown type %d", sockets[i].type);
 955                 }
 956 }
 957
 958 static void
 959 cleanup_socket(void)
 960 {
 961         if (socket_name[0])
 962                 unlink(socket_name);
 963         if (socket_dir[0])
 964                 rmdir(socket_dir);
 965 }
 966
 967 void
 968 cleanup_exit(int i)
 969 {
 970         cleanup_socket();
 971         _exit(i);
 972 }
 973
 974 /*ARGSUSED*/
 975 static void
 976 cleanup_handler(int sig)
 977 {
 978         cleanup_socket();
 979 #ifdef ENABLE_PKCS11
 980         pkcs11_terminate();
 981 #endif
 982         _exit(2);
 983 }
 984
 985 static void
 986 check_parent_exists(void)
 987 {
 988         /*
 989          * If our parent has exited then getppid() will return (pid_t)1,
 990          * so testing for that should be safe.
 991          */
 992         if (parent_pid != -1 && getppid() != parent_pid) {
 993                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 994                 cleanup_socket();
 995                 _exit(2);
 996         }
 997 }
 998
 999 static void
1000 usage(void)
1001 {
1002         fprintf(stderr, "usage: %s [options] [command [arg ...]]\n",
1003             __progname);
1004         fprintf(stderr, "Options:\n");
1005         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1006         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1007         fprintf(stderr, "  -k          Kill the current agent.\n");
1008         fprintf(stderr, "  -d          Debug mode.\n");
1009         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1010         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1011         exit(1);
1012 }
1013
1014 int
1015 main(int ac, char **av)
1016 {
1017         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1018         int sock, fd, ch, result, saved_errno;
1019         u_int nalloc;
1020         char *shell, *format, *pidstr, *agentsocket = NULL;
1021         fd_set *readsetp = NULL, *writesetp = NULL;
1022         struct sockaddr_un sunaddr;
1023 #ifdef HAVE_SETRLIMIT
1024         struct rlimit rlim;
1025 #endif
1026         int prev_mask;
1027         extern int optind;
1028         extern char *optarg;
1029         pid_t pid;
1030         char pidstrbuf[1 + 3 * sizeof pid];
1031         struct timeval *tvp = NULL;
1032         size_t len;
1033
1034         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1035         sanitise_stdfd();
1036
1037         /* drop */
1038         setegid(getgid());
1039         setgid(getgid());
1040
1041 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1042         /* Disable ptrace on Linux without sgid bit */
1043         prctl(PR_SET_DUMPABLE, 0);
1044 #endif
1045
1046         OpenSSL_add_all_algorithms();
1047
1048         __progname = ssh_get_progname(av[0]);
1049         seed_rng();
1050
1051         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1052                 switch (ch) {
1053                 case 'c':
1054                         if (s_flag)
1055                                 usage();
1056                         c_flag++;
1057                         break;
1058                 case 'k':
1059                         k_flag++;
1060                         break;
1061                 case 's':
1062                         if (c_flag)
1063                                 usage();
1064                         s_flag++;
1065                         break;
1066                 case 'd':
1067                         if (d_flag)
1068                                 usage();
1069                         d_flag++;
1070                         break;
1071                 case 'a':
1072                         agentsocket = optarg;
1073                         break;
1074                 case 't':
1075                         if ((lifetime = convtime(optarg)) == -1) {
1076                                 fprintf(stderr, "Invalid lifetime\n");
1077                                 usage();
1078                         }
1079                         break;
1080                 default:
1081                         usage();
1082                 }
1083         }
1084         ac -= optind;
1085         av += optind;
1086
1087         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1088                 usage();
1089
1090         if (ac == 0 && !c_flag && !s_flag) {
1091                 shell = getenv("SHELL");
1092                 if (shell != NULL && (len = strlen(shell)) > 2 &&
1093                     strncmp(shell + len - 3, "csh", 3) == 0)
1094                         c_flag = 1;
1095         }
1096         if (k_flag) {
1097                 const char *errstr = NULL;
1098
1099                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1100                 if (pidstr == NULL) {
1101                         fprintf(stderr, "%s not set, cannot kill agent\n",
1102                             SSH_AGENTPID_ENV_NAME);
1103                         exit(1);
1104                 }
1105                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1106                 if (errstr) {
1107                         fprintf(stderr,
1108                             "%s=\"%s\", which is not a good PID: %s\n",
1109                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1110                         exit(1);
1111                 }
1112                 if (kill(pid, SIGTERM) == -1) {
1113                         perror("kill");
1114                         exit(1);
1115                 }
1116                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1117                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1118                 printf(format, SSH_AGENTPID_ENV_NAME);
1119                 printf("echo Agent pid %ld killed;\n", (long)pid);
1120                 exit(0);
1121         }
1122         parent_pid = getpid();
1123
1124         if (agentsocket == NULL) {
1125                 /* Create private directory for agent socket */
1126                 mktemp_proto(socket_dir, sizeof(socket_dir));
1127                 if (mkdtemp(socket_dir) == NULL) {
1128                         perror("mkdtemp: private socket dir");
1129                         exit(1);
1130                 }
1131                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1132                     (long)parent_pid);
1133         } else {
1134                 /* Try to use specified agent socket */
1135                 socket_dir[0] = '\0';
1136                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1137         }
1138
1139         /*
1140          * Create socket early so it will exist before command gets run from
1141          * the parent.
1142          */
1143         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1144         if (sock < 0) {
1145                 perror("socket");
1146                 *socket_name = '\0'; /* Don't unlink any existing file */
1147                 cleanup_exit(1);
1148         }
1149         memset(&sunaddr, 0, sizeof(sunaddr));
1150         sunaddr.sun_family = AF_UNIX;
1151         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1152         prev_mask = umask(0177);
1153         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1154                 perror("bind");
1155                 *socket_name = '\0'; /* Don't unlink any existing file */
1156                 umask(prev_mask);
1157                 cleanup_exit(1);
1158         }
1159         umask(prev_mask);
1160         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1161                 perror("listen");
1162                 cleanup_exit(1);
1163         }
1164
1165         /*
1166          * Fork, and have the parent execute the command, if any, or present
1167          * the socket data.  The child continues as the authentication agent.
1168          */
1169         if (d_flag) {
1170                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1171                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1172                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1173                     SSH_AUTHSOCKET_ENV_NAME);
1174                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1175                 goto skip;
1176         }
1177         pid = fork();
1178         if (pid == -1) {
1179                 perror("fork");
1180                 cleanup_exit(1);
1181         }
1182         if (pid != 0) {         /* Parent - execute the given command. */
1183                 close(sock);
1184                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1185                 if (ac == 0) {
1186                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1187                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1188                             SSH_AUTHSOCKET_ENV_NAME);
1189                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1190                             SSH_AGENTPID_ENV_NAME);
1191                         printf("echo Agent pid %ld;\n", (long)pid);
1192                         exit(0);
1193                 }
1194                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1195                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1196                         perror("setenv");
1197                         exit(1);
1198                 }
1199                 execvp(av[0], av);
1200                 perror(av[0]);
1201                 exit(1);
1202         }
1203         /* child */
1204         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1205
1206         if (setsid() == -1) {
1207                 error("setsid: %s", strerror(errno));
1208                 cleanup_exit(1);
1209         }
1210
1211         (void)chdir("/");
1212         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1213                 /* XXX might close listen socket */
1214                 (void)dup2(fd, STDIN_FILENO);
1215                 (void)dup2(fd, STDOUT_FILENO);
1216                 (void)dup2(fd, STDERR_FILENO);
1217                 if (fd > 2)
1218                         close(fd);
1219         }
1220
1221 #ifdef HAVE_SETRLIMIT
1222         /* deny core dumps, since memory contains unencrypted private keys */
1223         rlim.rlim_cur = rlim.rlim_max = 0;
1224         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1225                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1226                 cleanup_exit(1);
1227         }
1228 #endif
1229
1230 skip:
1231
1232 #ifdef ENABLE_PKCS11
1233         pkcs11_init(0);
1234 #endif
1235         new_socket(AUTH_SOCKET, sock);
1236         if (ac > 0)
1237                 parent_alive_interval = 10;
1238         idtab_init();
1239         signal(SIGPIPE, SIG_IGN);
1240         signal(SIGINT, d_flag ? cleanup_handler : SIG_IGN);
1241         signal(SIGHUP, cleanup_handler);
1242         signal(SIGTERM, cleanup_handler);
1243         nalloc = 0;
1244
1245         while (1) {
1246                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1247                 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1248                 saved_errno = errno;
1249                 if (parent_alive_interval != 0)
1250                         check_parent_exists();
1251                 (void) reaper();        /* remove expired keys */
1252                 if (result < 0) {
1253                         if (saved_errno == EINTR)
1254                                 continue;
1255                         fatal("select: %s", strerror(saved_errno));
1256                 } else if (result > 0)
1257                         after_select(readsetp, writesetp);
1258         }
1259         /* NOTREACHED */
1260 }