ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.183 2014/02/02 03:44:31 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 "openbsd-compat/openssl-compat.h"
  54
  55 #include <errno.h>
  56 #include <fcntl.h>
  57 #ifdef HAVE_PATHS_H
  58 # include <paths.h>
  59 #endif
  60 #include <signal.h>
  61 #include <stdarg.h>
  62 #include <stdio.h>
  63 #include <stdlib.h>
  64 #include <time.h>
  65 #include <string.h>
  66 #include <unistd.h>
  67
  68 #include "xmalloc.h"
  69 #include "ssh.h"
  70 #include "rsa.h"
  71 #include "buffer.h"
  72 #include "key.h"
  73 #include "authfd.h"
  74 #include "compat.h"
  75 #include "log.h"
  76 #include "misc.h"
  77 #include "digest.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         struct ssh_digest_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                 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL ||
 288                     ssh_digest_update(md, buf, 32) < 0 ||
 289                     ssh_digest_update(md, session_id, 16) < 0 ||
 290                     ssh_digest_final(md, mdbuf, sizeof(mdbuf)) < 0)
 291                         fatal("%s: md5 failed", __func__);
 292                 ssh_digest_free(md);
 293
 294                 /* Send the response. */
 295                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 296                 for (i = 0; i < 16; i++)
 297                         buffer_put_char(&msg, mdbuf[i]);
 298                 goto send;
 299         }
 300
 301 failure:
 302         /* Unknown identity or protocol error.  Send failure. */
 303         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 304 send:
 305         buffer_put_int(&e->output, buffer_len(&msg));
 306         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 307         key_free(key);
 308         BN_clear_free(challenge);
 309         buffer_free(&msg);
 310 }
 311
 312 /* ssh2 only */
 313 static void
 314 process_sign_request2(SocketEntry *e)
 315 {
 316         u_char *blob, *data, *signature = NULL;
 317         u_int blen, dlen, slen = 0;
 318         extern int datafellows;
 319         int odatafellows;
 320         int ok = -1, flags;
 321         Buffer msg;
 322         Key *key;
 323
 324         datafellows = 0;
 325
 326         blob = buffer_get_string(&e->request, &blen);
 327         data = buffer_get_string(&e->request, &dlen);
 328
 329         flags = buffer_get_int(&e->request);
 330         odatafellows = datafellows;
 331         if (flags & SSH_AGENT_OLD_SIGNATURE)
 332                 datafellows = SSH_BUG_SIGBLOB;
 333
 334         key = key_from_blob(blob, blen);
 335         if (key != NULL) {
 336                 Identity *id = lookup_identity(key, 2);
 337                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 338                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 339                 key_free(key);
 340         }
 341         buffer_init(&msg);
 342         if (ok == 0) {
 343                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 344                 buffer_put_string(&msg, signature, slen);
 345         } else {
 346                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 347         }
 348         buffer_put_int(&e->output, buffer_len(&msg));
 349         buffer_append(&e->output, buffer_ptr(&msg),
 350             buffer_len(&msg));
 351         buffer_free(&msg);
 352         free(data);
 353         free(blob);
 354         free(signature);
 355         datafellows = odatafellows;
 356 }
 357
 358 /* shared */
 359 static void
 360 process_remove_identity(SocketEntry *e, int version)
 361 {
 362         u_int blen, bits;
 363         int success = 0;
 364         Key *key = NULL;
 365         u_char *blob;
 366
 367         switch (version) {
 368         case 1:
 369                 key = key_new(KEY_RSA1);
 370                 bits = buffer_get_int(&e->request);
 371                 buffer_get_bignum(&e->request, key->rsa->e);
 372                 buffer_get_bignum(&e->request, key->rsa->n);
 373
 374                 if (bits != key_size(key))
 375                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 376                             key_size(key), bits);
 377                 break;
 378         case 2:
 379                 blob = buffer_get_string(&e->request, &blen);
 380                 key = key_from_blob(blob, blen);
 381                 free(blob);
 382                 break;
 383         }
 384         if (key != NULL) {
 385                 Identity *id = lookup_identity(key, version);
 386                 if (id != NULL) {
 387                         /*
 388                          * We have this key.  Free the old key.  Since we
 389                          * don't want to leave empty slots in the middle of
 390                          * the array, we actually free the key there and move
 391                          * all the entries between the empty slot and the end
 392                          * of the array.
 393                          */
 394                         Idtab *tab = idtab_lookup(version);
 395                         if (tab->nentries < 1)
 396                                 fatal("process_remove_identity: "
 397                                     "internal error: tab->nentries %d",
 398                                     tab->nentries);
 399                         TAILQ_REMOVE(&tab->idlist, id, next);
 400                         free_identity(id);
 401                         tab->nentries--;
 402                         success = 1;
 403                 }
 404                 key_free(key);
 405         }
 406         buffer_put_int(&e->output, 1);
 407         buffer_put_char(&e->output,
 408             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 409 }
 410
 411 static void
 412 process_remove_all_identities(SocketEntry *e, int version)
 413 {
 414         Idtab *tab = idtab_lookup(version);
 415         Identity *id;
 416
 417         /* Loop over all identities and clear the keys. */
 418         for (id = TAILQ_FIRST(&tab->idlist); id;
 419             id = TAILQ_FIRST(&tab->idlist)) {
 420                 TAILQ_REMOVE(&tab->idlist, id, next);
 421                 free_identity(id);
 422         }
 423
 424         /* Mark that there are no identities. */
 425         tab->nentries = 0;
 426
 427         /* Send success. */
 428         buffer_put_int(&e->output, 1);
 429         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 430 }
 431
 432 /* removes expired keys and returns number of seconds until the next expiry */
 433 static time_t
 434 reaper(void)
 435 {
 436         time_t deadline = 0, now = monotime();
 437         Identity *id, *nxt;
 438         int version;
 439         Idtab *tab;
 440
 441         for (version = 1; version < 3; version++) {
 442                 tab = idtab_lookup(version);
 443                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 444                         nxt = TAILQ_NEXT(id, next);
 445                         if (id->death == 0)
 446                                 continue;
 447                         if (now >= id->death) {
 448                                 debug("expiring key '%s'", id->comment);
 449                                 TAILQ_REMOVE(&tab->idlist, id, next);
 450                                 free_identity(id);
 451                                 tab->nentries--;
 452                         } else
 453                                 deadline = (deadline == 0) ? id->death :
 454                                     MIN(deadline, id->death);
 455                 }
 456         }
 457         if (deadline == 0 || deadline <= now)
 458                 return 0;
 459         else
 460                 return (deadline - now);
 461 }
 462
 463 static void
 464 process_add_identity(SocketEntry *e, int version)
 465 {
 466         Idtab *tab = idtab_lookup(version);
 467         Identity *id;
 468         int type, success = 0, confirm = 0;
 469         char *comment;
 470         time_t death = 0;
 471         Key *k = NULL;
 472
 473         switch (version) {
 474         case 1:
 475                 k = key_new_private(KEY_RSA1);
 476                 (void) buffer_get_int(&e->request);             /* ignored */
 477                 buffer_get_bignum(&e->request, k->rsa->n);
 478                 buffer_get_bignum(&e->request, k->rsa->e);
 479                 buffer_get_bignum(&e->request, k->rsa->d);
 480                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 481
 482                 /* SSH and SSL have p and q swapped */
 483                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 484                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 485
 486                 /* Generate additional parameters */
 487                 rsa_generate_additional_parameters(k->rsa);
 488
 489                 /* enable blinding */
 490                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 491                         error("process_add_identity: RSA_blinding_on failed");
 492                         key_free(k);
 493                         goto send;
 494                 }
 495                 break;
 496         case 2:
 497                 k = key_private_deserialize(&e->request);
 498                 if (k == NULL) {
 499                         buffer_clear(&e->request);
 500                         goto send;
 501                 }
 502                 break;
 503         }
 504         comment = buffer_get_string(&e->request, NULL);
 505         if (k == NULL) {
 506                 free(comment);
 507                 goto send;
 508         }
 509         while (buffer_len(&e->request)) {
 510                 switch ((type = buffer_get_char(&e->request))) {
 511                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 512                         death = monotime() + buffer_get_int(&e->request);
 513                         break;
 514                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 515                         confirm = 1;
 516                         break;
 517                 default:
 518                         error("process_add_identity: "
 519                             "Unknown constraint type %d", type);
 520                         free(comment);
 521                         key_free(k);
 522                         goto send;
 523                 }
 524         }
 525         success = 1;
 526         if (lifetime && !death)
 527                 death = monotime() + lifetime;
 528         if ((id = lookup_identity(k, version)) == NULL) {
 529                 id = xcalloc(1, sizeof(Identity));
 530                 id->key = k;
 531                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 532                 /* Increment the number of identities. */
 533                 tab->nentries++;
 534         } else {
 535                 key_free(k);
 536                 free(id->comment);
 537         }
 538         id->comment = comment;
 539         id->death = death;
 540         id->confirm = confirm;
 541 send:
 542         buffer_put_int(&e->output, 1);
 543         buffer_put_char(&e->output,
 544             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 545 }
 546
 547 /* XXX todo: encrypt sensitive data with passphrase */
 548 static void
 549 process_lock_agent(SocketEntry *e, int lock)
 550 {
 551         int success = 0;
 552         char *passwd;
 553
 554         passwd = buffer_get_string(&e->request, NULL);
 555         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 556                 locked = 0;
 557                 explicit_bzero(lock_passwd, strlen(lock_passwd));
 558                 free(lock_passwd);
 559                 lock_passwd = NULL;
 560                 success = 1;
 561         } else if (!locked && lock) {
 562                 locked = 1;
 563                 lock_passwd = xstrdup(passwd);
 564                 success = 1;
 565         }
 566         explicit_bzero(passwd, strlen(passwd));
 567         free(passwd);
 568
 569         buffer_put_int(&e->output, 1);
 570         buffer_put_char(&e->output,
 571             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 572 }
 573
 574 static void
 575 no_identities(SocketEntry *e, u_int type)
 576 {
 577         Buffer msg;
 578
 579         buffer_init(&msg);
 580         buffer_put_char(&msg,
 581             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 582             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 583         buffer_put_int(&msg, 0);
 584         buffer_put_int(&e->output, buffer_len(&msg));
 585         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 586         buffer_free(&msg);
 587 }
 588
 589 #ifdef ENABLE_PKCS11
 590 static void
 591 process_add_smartcard_key(SocketEntry *e)
 592 {
 593         char *provider = NULL, *pin;
 594         int i, type, version, count = 0, success = 0, confirm = 0;
 595         time_t death = 0;
 596         Key **keys = NULL, *k;
 597         Identity *id;
 598         Idtab *tab;
 599
 600         provider = buffer_get_string(&e->request, NULL);
 601         pin = buffer_get_string(&e->request, NULL);
 602
 603         while (buffer_len(&e->request)) {
 604                 switch ((type = buffer_get_char(&e->request))) {
 605                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 606                         death = monotime() + buffer_get_int(&e->request);
 607                         break;
 608                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 609                         confirm = 1;
 610                         break;
 611                 default:
 612                         error("process_add_smartcard_key: "
 613                             "Unknown constraint type %d", type);
 614                         goto send;
 615                 }
 616         }
 617         if (lifetime && !death)
 618                 death = monotime() + lifetime;
 619
 620         count = pkcs11_add_provider(provider, pin, &keys);
 621         for (i = 0; i < count; i++) {
 622                 k = keys[i];
 623                 version = k->type == KEY_RSA1 ? 1 : 2;
 624                 tab = idtab_lookup(version);
 625                 if (lookup_identity(k, version) == NULL) {
 626                         id = xcalloc(1, sizeof(Identity));
 627                         id->key = k;
 628                         id->provider = xstrdup(provider);
 629                         id->comment = xstrdup(provider); /* XXX */
 630                         id->death = death;
 631                         id->confirm = confirm;
 632                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 633                         tab->nentries++;
 634                         success = 1;
 635                 } else {
 636                         key_free(k);
 637                 }
 638                 keys[i] = NULL;
 639         }
 640 send:
 641         free(pin);
 642         free(provider);
 643         free(keys);
 644         buffer_put_int(&e->output, 1);
 645         buffer_put_char(&e->output,
 646             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 647 }
 648
 649 static void
 650 process_remove_smartcard_key(SocketEntry *e)
 651 {
 652         char *provider = NULL, *pin = NULL;
 653         int version, success = 0;
 654         Identity *id, *nxt;
 655         Idtab *tab;
 656
 657         provider = buffer_get_string(&e->request, NULL);
 658         pin = buffer_get_string(&e->request, NULL);
 659         free(pin);
 660
 661         for (version = 1; version < 3; version++) {
 662                 tab = idtab_lookup(version);
 663                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 664                         nxt = TAILQ_NEXT(id, next);
 665                         /* Skip file--based keys */
 666                         if (id->provider == NULL)
 667                                 continue;
 668                         if (!strcmp(provider, id->provider)) {
 669                                 TAILQ_REMOVE(&tab->idlist, id, next);
 670                                 free_identity(id);
 671                                 tab->nentries--;
 672                         }
 673                 }
 674         }
 675         if (pkcs11_del_provider(provider) == 0)
 676                 success = 1;
 677         else
 678                 error("process_remove_smartcard_key:"
 679                     " pkcs11_del_provider failed");
 680         free(provider);
 681         buffer_put_int(&e->output, 1);
 682         buffer_put_char(&e->output,
 683             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 684 }
 685 #endif /* ENABLE_PKCS11 */
 686
 687 /* dispatch incoming messages */
 688
 689 static void
 690 process_message(SocketEntry *e)
 691 {
 692         u_int msg_len, type;
 693         u_char *cp;
 694
 695         if (buffer_len(&e->input) < 5)
 696                 return;         /* Incomplete message. */
 697         cp = buffer_ptr(&e->input);
 698         msg_len = get_u32(cp);
 699         if (msg_len > 256 * 1024) {
 700                 close_socket(e);
 701                 return;
 702         }
 703         if (buffer_len(&e->input) < msg_len + 4)
 704                 return;
 705
 706         /* move the current input to e->request */
 707         buffer_consume(&e->input, 4);
 708         buffer_clear(&e->request);
 709         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 710         buffer_consume(&e->input, msg_len);
 711         type = buffer_get_char(&e->request);
 712
 713         /* check wheter agent is locked */
 714         if (locked && type != SSH_AGENTC_UNLOCK) {
 715                 buffer_clear(&e->request);
 716                 switch (type) {
 717                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 718                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 719                         /* send empty lists */
 720                         no_identities(e, type);
 721                         break;
 722                 default:
 723                         /* send a fail message for all other request types */
 724                         buffer_put_int(&e->output, 1);
 725                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 726                 }
 727                 return;
 728         }
 729
 730         debug("type %d", type);
 731         switch (type) {
 732         case SSH_AGENTC_LOCK:
 733         case SSH_AGENTC_UNLOCK:
 734                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 735                 break;
 736         /* ssh1 */
 737         case SSH_AGENTC_RSA_CHALLENGE:
 738                 process_authentication_challenge1(e);
 739                 break;
 740         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 741                 process_request_identities(e, 1);
 742                 break;
 743         case SSH_AGENTC_ADD_RSA_IDENTITY:
 744         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 745                 process_add_identity(e, 1);
 746                 break;
 747         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 748                 process_remove_identity(e, 1);
 749                 break;
 750         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 751                 process_remove_all_identities(e, 1);
 752                 break;
 753         /* ssh2 */
 754         case SSH2_AGENTC_SIGN_REQUEST:
 755                 process_sign_request2(e);
 756                 break;
 757         case SSH2_AGENTC_REQUEST_IDENTITIES:
 758                 process_request_identities(e, 2);
 759                 break;
 760         case SSH2_AGENTC_ADD_IDENTITY:
 761         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 762                 process_add_identity(e, 2);
 763                 break;
 764         case SSH2_AGENTC_REMOVE_IDENTITY:
 765                 process_remove_identity(e, 2);
 766                 break;
 767         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 768                 process_remove_all_identities(e, 2);
 769                 break;
 770 #ifdef ENABLE_PKCS11
 771         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 772         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 773                 process_add_smartcard_key(e);
 774                 break;
 775         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 776                 process_remove_smartcard_key(e);
 777                 break;
 778 #endif /* ENABLE_PKCS11 */
 779         default:
 780                 /* Unknown message.  Respond with failure. */
 781                 error("Unknown message %d", type);
 782                 buffer_clear(&e->request);
 783                 buffer_put_int(&e->output, 1);
 784                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 785                 break;
 786         }
 787 }
 788
 789 static void
 790 new_socket(sock_type type, int fd)
 791 {
 792         u_int i, old_alloc, new_alloc;
 793
 794         set_nonblock(fd);
 795
 796         if (fd > max_fd)
 797                 max_fd = fd;
 798
 799         for (i = 0; i < sockets_alloc; i++)
 800                 if (sockets[i].type == AUTH_UNUSED) {
 801                         sockets[i].fd = fd;
 802                         buffer_init(&sockets[i].input);
 803                         buffer_init(&sockets[i].output);
 804                         buffer_init(&sockets[i].request);
 805                         sockets[i].type = type;
 806                         return;
 807                 }
 808         old_alloc = sockets_alloc;
 809         new_alloc = sockets_alloc + 10;
 810         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 811         for (i = old_alloc; i < new_alloc; i++)
 812                 sockets[i].type = AUTH_UNUSED;
 813         sockets_alloc = new_alloc;
 814         sockets[old_alloc].fd = fd;
 815         buffer_init(&sockets[old_alloc].input);
 816         buffer_init(&sockets[old_alloc].output);
 817         buffer_init(&sockets[old_alloc].request);
 818         sockets[old_alloc].type = type;
 819 }
 820
 821 static int
 822 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
 823     struct timeval **tvpp)
 824 {
 825         u_int i, sz;
 826         int n = 0;
 827         static struct timeval tv;
 828         time_t deadline;
 829
 830         for (i = 0; i < sockets_alloc; i++) {
 831                 switch (sockets[i].type) {
 832                 case AUTH_SOCKET:
 833                 case AUTH_CONNECTION:
 834                         n = MAX(n, sockets[i].fd);
 835                         break;
 836                 case AUTH_UNUSED:
 837                         break;
 838                 default:
 839                         fatal("Unknown socket type %d", sockets[i].type);
 840                         break;
 841                 }
 842         }
 843
 844         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 845         if (*fdrp == NULL || sz > *nallocp) {
 846                 free(*fdrp);
 847                 free(*fdwp);
 848                 *fdrp = xmalloc(sz);
 849                 *fdwp = xmalloc(sz);
 850                 *nallocp = sz;
 851         }
 852         if (n < *fdl)
 853                 debug("XXX shrink: %d < %d", n, *fdl);
 854         *fdl = n;
 855         memset(*fdrp, 0, sz);
 856         memset(*fdwp, 0, sz);
 857
 858         for (i = 0; i < sockets_alloc; i++) {
 859                 switch (sockets[i].type) {
 860                 case AUTH_SOCKET:
 861                 case AUTH_CONNECTION:
 862                         FD_SET(sockets[i].fd, *fdrp);
 863                         if (buffer_len(&sockets[i].output) > 0)
 864                                 FD_SET(sockets[i].fd, *fdwp);
 865                         break;
 866                 default:
 867                         break;
 868                 }
 869         }
 870         deadline = reaper();
 871         if (parent_alive_interval != 0)
 872                 deadline = (deadline == 0) ? parent_alive_interval :
 873                     MIN(deadline, parent_alive_interval);
 874         if (deadline == 0) {
 875                 *tvpp = NULL;
 876         } else {
 877                 tv.tv_sec = deadline;
 878                 tv.tv_usec = 0;
 879                 *tvpp = &tv;
 880         }
 881         return (1);
 882 }
 883
 884 static void
 885 after_select(fd_set *readset, fd_set *writeset)
 886 {
 887         struct sockaddr_un sunaddr;
 888         socklen_t slen;
 889         char buf[1024];
 890         int len, sock;
 891         u_int i, orig_alloc;
 892         uid_t euid;
 893         gid_t egid;
 894
 895         for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++)
 896                 switch (sockets[i].type) {
 897                 case AUTH_UNUSED:
 898                         break;
 899                 case AUTH_SOCKET:
 900                         if (FD_ISSET(sockets[i].fd, readset)) {
 901                                 slen = sizeof(sunaddr);
 902                                 sock = accept(sockets[i].fd,
 903                                     (struct sockaddr *)&sunaddr, &slen);
 904                                 if (sock < 0) {
 905                                         error("accept from AUTH_SOCKET: %s",
 906                                             strerror(errno));
 907                                         break;
 908                                 }
 909                                 if (getpeereid(sock, &euid, &egid) < 0) {
 910                                         error("getpeereid %d failed: %s",
 911                                             sock, strerror(errno));
 912                                         close(sock);
 913                                         break;
 914                                 }
 915                                 if ((euid != 0) && (getuid() != euid)) {
 916                                         error("uid mismatch: "
 917                                             "peer euid %u != uid %u",
 918                                             (u_int) euid, (u_int) getuid());
 919                                         close(sock);
 920                                         break;
 921                                 }
 922                                 new_socket(AUTH_CONNECTION, sock);
 923                         }
 924                         break;
 925                 case AUTH_CONNECTION:
 926                         if (buffer_len(&sockets[i].output) > 0 &&
 927                             FD_ISSET(sockets[i].fd, writeset)) {
 928                                 len = write(sockets[i].fd,
 929                                     buffer_ptr(&sockets[i].output),
 930                                     buffer_len(&sockets[i].output));
 931                                 if (len == -1 && (errno == EAGAIN ||
 932                                     errno == EWOULDBLOCK ||
 933                                     errno == EINTR))
 934                                         continue;
 935                                 if (len <= 0) {
 936                                         close_socket(&sockets[i]);
 937                                         break;
 938                                 }
 939                                 buffer_consume(&sockets[i].output, len);
 940                         }
 941                         if (FD_ISSET(sockets[i].fd, readset)) {
 942                                 len = read(sockets[i].fd, buf, sizeof(buf));
 943                                 if (len == -1 && (errno == EAGAIN ||
 944                                     errno == EWOULDBLOCK ||
 945                                     errno == EINTR))
 946                                         continue;
 947                                 if (len <= 0) {
 948                                         close_socket(&sockets[i]);
 949                                         break;
 950                                 }
 951                                 buffer_append(&sockets[i].input, buf, len);
 952                                 process_message(&sockets[i]);
 953                         }
 954                         break;
 955                 default:
 956                         fatal("Unknown type %d", sockets[i].type);
 957                 }
 958 }
 959
 960 static void
 961 cleanup_socket(void)
 962 {
 963         if (socket_name[0])
 964                 unlink(socket_name);
 965         if (socket_dir[0])
 966                 rmdir(socket_dir);
 967 }
 968
 969 void
 970 cleanup_exit(int i)
 971 {
 972         cleanup_socket();
 973         _exit(i);
 974 }
 975
 976 /*ARGSUSED*/
 977 static void
 978 cleanup_handler(int sig)
 979 {
 980         cleanup_socket();
 981 #ifdef ENABLE_PKCS11
 982         pkcs11_terminate();
 983 #endif
 984         _exit(2);
 985 }
 986
 987 static void
 988 check_parent_exists(void)
 989 {
 990         /*
 991          * If our parent has exited then getppid() will return (pid_t)1,
 992          * so testing for that should be safe.
 993          */
 994         if (parent_pid != -1 && getppid() != parent_pid) {
 995                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 996                 cleanup_socket();
 997                 _exit(2);
 998         }
 999 }
1000
1001 static void
1002 usage(void)
1003 {
1004         fprintf(stderr, "usage: %s [options] [command [arg ...]]\n",
1005             __progname);
1006         fprintf(stderr, "Options:\n");
1007         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1008         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1009         fprintf(stderr, "  -k          Kill the current agent.\n");
1010         fprintf(stderr, "  -d          Debug mode.\n");
1011         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1012         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1013         exit(1);
1014 }
1015
1016 int
1017 main(int ac, char **av)
1018 {
1019         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1020         int sock, fd, ch, result, saved_errno;
1021         u_int nalloc;
1022         char *shell, *format, *pidstr, *agentsocket = NULL;
1023         fd_set *readsetp = NULL, *writesetp = NULL;
1024         struct sockaddr_un sunaddr;
1025 #ifdef HAVE_SETRLIMIT
1026         struct rlimit rlim;
1027 #endif
1028         int prev_mask;
1029         extern int optind;
1030         extern char *optarg;
1031         pid_t pid;
1032         char pidstrbuf[1 + 3 * sizeof pid];
1033         struct timeval *tvp = NULL;
1034         size_t len;
1035
1036         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1037         sanitise_stdfd();
1038
1039         /* drop */
1040         setegid(getgid());
1041         setgid(getgid());
1042
1043 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1044         /* Disable ptrace on Linux without sgid bit */
1045         prctl(PR_SET_DUMPABLE, 0);
1046 #endif
1047
1048         OpenSSL_add_all_algorithms();
1049
1050         __progname = ssh_get_progname(av[0]);
1051         seed_rng();
1052
1053         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1054                 switch (ch) {
1055                 case 'c':
1056                         if (s_flag)
1057                                 usage();
1058                         c_flag++;
1059                         break;
1060                 case 'k':
1061                         k_flag++;
1062                         break;
1063                 case 's':
1064                         if (c_flag)
1065                                 usage();
1066                         s_flag++;
1067                         break;
1068                 case 'd':
1069                         if (d_flag)
1070                                 usage();
1071                         d_flag++;
1072                         break;
1073                 case 'a':
1074                         agentsocket = optarg;
1075                         break;
1076                 case 't':
1077                         if ((lifetime = convtime(optarg)) == -1) {
1078                                 fprintf(stderr, "Invalid lifetime\n");
1079                                 usage();
1080                         }
1081                         break;
1082                 default:
1083                         usage();
1084                 }
1085         }
1086         ac -= optind;
1087         av += optind;
1088
1089         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1090                 usage();
1091
1092         if (ac == 0 && !c_flag && !s_flag) {
1093                 shell = getenv("SHELL");
1094                 if (shell != NULL && (len = strlen(shell)) > 2 &&
1095                     strncmp(shell + len - 3, "csh", 3) == 0)
1096                         c_flag = 1;
1097         }
1098         if (k_flag) {
1099                 const char *errstr = NULL;
1100
1101                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1102                 if (pidstr == NULL) {
1103                         fprintf(stderr, "%s not set, cannot kill agent\n",
1104                             SSH_AGENTPID_ENV_NAME);
1105                         exit(1);
1106                 }
1107                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1108                 if (errstr) {
1109                         fprintf(stderr,
1110                             "%s=\"%s\", which is not a good PID: %s\n",
1111                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1112                         exit(1);
1113                 }
1114                 if (kill(pid, SIGTERM) == -1) {
1115                         perror("kill");
1116                         exit(1);
1117                 }
1118                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1119                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1120                 printf(format, SSH_AGENTPID_ENV_NAME);
1121                 printf("echo Agent pid %ld killed;\n", (long)pid);
1122                 exit(0);
1123         }
1124         parent_pid = getpid();
1125
1126         if (agentsocket == NULL) {
1127                 /* Create private directory for agent socket */
1128                 mktemp_proto(socket_dir, sizeof(socket_dir));
1129                 if (mkdtemp(socket_dir) == NULL) {
1130                         perror("mkdtemp: private socket dir");
1131                         exit(1);
1132                 }
1133                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1134                     (long)parent_pid);
1135         } else {
1136                 /* Try to use specified agent socket */
1137                 socket_dir[0] = '\0';
1138                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1139         }
1140
1141         /*
1142          * Create socket early so it will exist before command gets run from
1143          * the parent.
1144          */
1145         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1146         if (sock < 0) {
1147                 perror("socket");
1148                 *socket_name = '\0'; /* Don't unlink any existing file */
1149                 cleanup_exit(1);
1150         }
1151         memset(&sunaddr, 0, sizeof(sunaddr));
1152         sunaddr.sun_family = AF_UNIX;
1153         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1154         prev_mask = umask(0177);
1155         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1156                 perror("bind");
1157                 *socket_name = '\0'; /* Don't unlink any existing file */
1158                 umask(prev_mask);
1159                 cleanup_exit(1);
1160         }
1161         umask(prev_mask);
1162         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1163                 perror("listen");
1164                 cleanup_exit(1);
1165         }
1166
1167         /*
1168          * Fork, and have the parent execute the command, if any, or present
1169          * the socket data.  The child continues as the authentication agent.
1170          */
1171         if (d_flag) {
1172                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1173                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1174                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1175                     SSH_AUTHSOCKET_ENV_NAME);
1176                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1177                 goto skip;
1178         }
1179         pid = fork();
1180         if (pid == -1) {
1181                 perror("fork");
1182                 cleanup_exit(1);
1183         }
1184         if (pid != 0) {         /* Parent - execute the given command. */
1185                 close(sock);
1186                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1187                 if (ac == 0) {
1188                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1189                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1190                             SSH_AUTHSOCKET_ENV_NAME);
1191                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1192                             SSH_AGENTPID_ENV_NAME);
1193                         printf("echo Agent pid %ld;\n", (long)pid);
1194                         exit(0);
1195                 }
1196                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1197                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1198                         perror("setenv");
1199                         exit(1);
1200                 }
1201                 execvp(av[0], av);
1202                 perror(av[0]);
1203                 exit(1);
1204         }
1205         /* child */
1206         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1207
1208         if (setsid() == -1) {
1209                 error("setsid: %s", strerror(errno));
1210                 cleanup_exit(1);
1211         }
1212
1213         (void)chdir("/");
1214         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1215                 /* XXX might close listen socket */
1216                 (void)dup2(fd, STDIN_FILENO);
1217                 (void)dup2(fd, STDOUT_FILENO);
1218                 (void)dup2(fd, STDERR_FILENO);
1219                 if (fd > 2)
1220                         close(fd);
1221         }
1222
1223 #ifdef HAVE_SETRLIMIT
1224         /* deny core dumps, since memory contains unencrypted private keys */
1225         rlim.rlim_cur = rlim.rlim_max = 0;
1226         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1227                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1228                 cleanup_exit(1);
1229         }
1230 #endif
1231
1232 skip:
1233
1234 #ifdef ENABLE_PKCS11
1235         pkcs11_init(0);
1236 #endif
1237         new_socket(AUTH_SOCKET, sock);
1238         if (ac > 0)
1239                 parent_alive_interval = 10;
1240         idtab_init();
1241         signal(SIGPIPE, SIG_IGN);
1242         signal(SIGINT, d_flag ? cleanup_handler : SIG_IGN);
1243         signal(SIGHUP, cleanup_handler);
1244         signal(SIGTERM, cleanup_handler);
1245         nalloc = 0;
1246
1247         while (1) {
1248                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1249                 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1250                 saved_errno = errno;
1251                 if (parent_alive_interval != 0)
1252                         check_parent_exists();
1253                 (void) reaper();        /* remove expired keys */
1254                 if (result < 0) {
1255                         if (saved_errno == EINTR)
1256                                 continue;
1257                         fatal("select: %s", strerror(saved_errno));
1258                 } else if (result > 0)
1259                         after_select(readsetp, writesetp);
1260         }
1261         /* NOTREACHED */
1262 }