crypto/openssh/ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.161 2009/03/23 19:38:04 tobias 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 SMARTCARD
  80 #include "scard.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         u_int death;
 109         u_int confirm;
 110 } Identity;
 111
 112 typedef struct {
 113         int nentries;
 114         TAILQ_HEAD(idqueue, identity) idlist;
 115 } Idtab;
 116
 117 /* private key table, one per protocol version */
 118 Idtab idtable[3];
 119
 120 int max_fd = 0;
 121
 122 /* pid of shell == parent of agent */
 123 pid_t parent_pid = -1;
 124 u_int parent_alive_interval = 0;
 125
 126 /* pathname and directory for AUTH_SOCKET */
 127 char socket_name[MAXPATHLEN];
 128 char socket_dir[MAXPATHLEN];
 129
 130 /* locking */
 131 int locked = 0;
 132 char *lock_passwd = NULL;
 133
 134 extern char *__progname;
 135
 136 /* Default lifetime (0 == forever) */
 137 static int lifetime = 0;
 138
 139 static void
 140 close_socket(SocketEntry *e)
 141 {
 142         close(e->fd);
 143         e->fd = -1;
 144         e->type = AUTH_UNUSED;
 145         buffer_free(&e->input);
 146         buffer_free(&e->output);
 147         buffer_free(&e->request);
 148 }
 149
 150 static void
 151 idtab_init(void)
 152 {
 153         int i;
 154
 155         for (i = 0; i <=2; i++) {
 156                 TAILQ_INIT(&idtable[i].idlist);
 157                 idtable[i].nentries = 0;
 158         }
 159 }
 160
 161 /* return private key table for requested protocol version */
 162 static Idtab *
 163 idtab_lookup(int version)
 164 {
 165         if (version < 1 || version > 2)
 166                 fatal("internal error, bad protocol version %d", version);
 167         return &idtable[version];
 168 }
 169
 170 static void
 171 free_identity(Identity *id)
 172 {
 173         key_free(id->key);
 174         xfree(id->comment);
 175         xfree(id);
 176 }
 177
 178 /* return matching private key for given public key */
 179 static Identity *
 180 lookup_identity(Key *key, int version)
 181 {
 182         Identity *id;
 183
 184         Idtab *tab = idtab_lookup(version);
 185         TAILQ_FOREACH(id, &tab->idlist, next) {
 186                 if (key_equal(key, id->key))
 187                         return (id);
 188         }
 189         return (NULL);
 190 }
 191
 192 /* Check confirmation of keysign request */
 193 static int
 194 confirm_key(Identity *id)
 195 {
 196         char *p;
 197         int ret = -1;
 198
 199         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 200         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 201             id->comment, p))
 202                 ret = 0;
 203         xfree(p);
 204
 205         return (ret);
 206 }
 207
 208 /* send list of supported public keys to 'client' */
 209 static void
 210 process_request_identities(SocketEntry *e, int version)
 211 {
 212         Idtab *tab = idtab_lookup(version);
 213         Identity *id;
 214         Buffer msg;
 215
 216         buffer_init(&msg);
 217         buffer_put_char(&msg, (version == 1) ?
 218             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 219         buffer_put_int(&msg, tab->nentries);
 220         TAILQ_FOREACH(id, &tab->idlist, next) {
 221                 if (id->key->type == KEY_RSA1) {
 222                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 223                         buffer_put_bignum(&msg, id->key->rsa->e);
 224                         buffer_put_bignum(&msg, id->key->rsa->n);
 225                 } else {
 226                         u_char *blob;
 227                         u_int blen;
 228                         key_to_blob(id->key, &blob, &blen);
 229                         buffer_put_string(&msg, blob, blen);
 230                         xfree(blob);
 231                 }
 232                 buffer_put_cstring(&msg, id->comment);
 233         }
 234         buffer_put_int(&e->output, buffer_len(&msg));
 235         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 236         buffer_free(&msg);
 237 }
 238
 239 /* ssh1 only */
 240 static void
 241 process_authentication_challenge1(SocketEntry *e)
 242 {
 243         u_char buf[32], mdbuf[16], session_id[16];
 244         u_int response_type;
 245         BIGNUM *challenge;
 246         Identity *id;
 247         int i, len;
 248         Buffer msg;
 249         MD5_CTX md;
 250         Key *key;
 251
 252         buffer_init(&msg);
 253         key = key_new(KEY_RSA1);
 254         if ((challenge = BN_new()) == NULL)
 255                 fatal("process_authentication_challenge1: BN_new failed");
 256
 257         (void) buffer_get_int(&e->request);                     /* ignored */
 258         buffer_get_bignum(&e->request, key->rsa->e);
 259         buffer_get_bignum(&e->request, key->rsa->n);
 260         buffer_get_bignum(&e->request, challenge);
 261
 262         /* Only protocol 1.1 is supported */
 263         if (buffer_len(&e->request) == 0)
 264                 goto failure;
 265         buffer_get(&e->request, session_id, 16);
 266         response_type = buffer_get_int(&e->request);
 267         if (response_type != 1)
 268                 goto failure;
 269
 270         id = lookup_identity(key, 1);
 271         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 272                 Key *private = id->key;
 273                 /* Decrypt the challenge using the private key. */
 274                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 275                         goto failure;
 276
 277                 /* The response is MD5 of decrypted challenge plus session id. */
 278                 len = BN_num_bytes(challenge);
 279                 if (len <= 0 || len > 32) {
 280                         logit("process_authentication_challenge: bad challenge length %d", len);
 281                         goto failure;
 282                 }
 283                 memset(buf, 0, 32);
 284                 BN_bn2bin(challenge, buf + 32 - len);
 285                 MD5_Init(&md);
 286                 MD5_Update(&md, buf, 32);
 287                 MD5_Update(&md, session_id, 16);
 288                 MD5_Final(mdbuf, &md);
 289
 290                 /* Send the response. */
 291                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 292                 for (i = 0; i < 16; i++)
 293                         buffer_put_char(&msg, mdbuf[i]);
 294                 goto send;
 295         }
 296
 297 failure:
 298         /* Unknown identity or protocol error.  Send failure. */
 299         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 300 send:
 301         buffer_put_int(&e->output, buffer_len(&msg));
 302         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 303         key_free(key);
 304         BN_clear_free(challenge);
 305         buffer_free(&msg);
 306 }
 307
 308 /* ssh2 only */
 309 static void
 310 process_sign_request2(SocketEntry *e)
 311 {
 312         u_char *blob, *data, *signature = NULL;
 313         u_int blen, dlen, slen = 0;
 314         extern int datafellows;
 315         int odatafellows;
 316         int ok = -1, flags;
 317         Buffer msg;
 318         Key *key;
 319
 320         datafellows = 0;
 321
 322         blob = buffer_get_string(&e->request, &blen);
 323         data = buffer_get_string(&e->request, &dlen);
 324
 325         flags = buffer_get_int(&e->request);
 326         odatafellows = datafellows;
 327         if (flags & SSH_AGENT_OLD_SIGNATURE)
 328                 datafellows = SSH_BUG_SIGBLOB;
 329
 330         key = key_from_blob(blob, blen);
 331         if (key != NULL) {
 332                 Identity *id = lookup_identity(key, 2);
 333                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 334                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 335                 key_free(key);
 336         }
 337         buffer_init(&msg);
 338         if (ok == 0) {
 339                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 340                 buffer_put_string(&msg, signature, slen);
 341         } else {
 342                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 343         }
 344         buffer_put_int(&e->output, buffer_len(&msg));
 345         buffer_append(&e->output, buffer_ptr(&msg),
 346             buffer_len(&msg));
 347         buffer_free(&msg);
 348         xfree(data);
 349         xfree(blob);
 350         if (signature != NULL)
 351                 xfree(signature);
 352         datafellows = odatafellows;
 353 }
 354
 355 /* shared */
 356 static void
 357 process_remove_identity(SocketEntry *e, int version)
 358 {
 359         u_int blen, bits;
 360         int success = 0;
 361         Key *key = NULL;
 362         u_char *blob;
 363
 364         switch (version) {
 365         case 1:
 366                 key = key_new(KEY_RSA1);
 367                 bits = buffer_get_int(&e->request);
 368                 buffer_get_bignum(&e->request, key->rsa->e);
 369                 buffer_get_bignum(&e->request, key->rsa->n);
 370
 371                 if (bits != key_size(key))
 372                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 373                             key_size(key), bits);
 374                 break;
 375         case 2:
 376                 blob = buffer_get_string(&e->request, &blen);
 377                 key = key_from_blob(blob, blen);
 378                 xfree(blob);
 379                 break;
 380         }
 381         if (key != NULL) {
 382                 Identity *id = lookup_identity(key, version);
 383                 if (id != NULL) {
 384                         /*
 385                          * We have this key.  Free the old key.  Since we
 386                          * don't want to leave empty slots in the middle of
 387                          * the array, we actually free the key there and move
 388                          * all the entries between the empty slot and the end
 389                          * of the array.
 390                          */
 391                         Idtab *tab = idtab_lookup(version);
 392                         if (tab->nentries < 1)
 393                                 fatal("process_remove_identity: "
 394                                     "internal error: tab->nentries %d",
 395                                     tab->nentries);
 396                         TAILQ_REMOVE(&tab->idlist, id, next);
 397                         free_identity(id);
 398                         tab->nentries--;
 399                         success = 1;
 400                 }
 401                 key_free(key);
 402         }
 403         buffer_put_int(&e->output, 1);
 404         buffer_put_char(&e->output,
 405             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 406 }
 407
 408 static void
 409 process_remove_all_identities(SocketEntry *e, int version)
 410 {
 411         Idtab *tab = idtab_lookup(version);
 412         Identity *id;
 413
 414         /* Loop over all identities and clear the keys. */
 415         for (id = TAILQ_FIRST(&tab->idlist); id;
 416             id = TAILQ_FIRST(&tab->idlist)) {
 417                 TAILQ_REMOVE(&tab->idlist, id, next);
 418                 free_identity(id);
 419         }
 420
 421         /* Mark that there are no identities. */
 422         tab->nentries = 0;
 423
 424         /* Send success. */
 425         buffer_put_int(&e->output, 1);
 426         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 427 }
 428
 429 /* removes expired keys and returns number of seconds until the next expiry */
 430 static u_int
 431 reaper(void)
 432 {
 433         u_int deadline = 0, now = time(NULL);
 434         Identity *id, *nxt;
 435         int version;
 436         Idtab *tab;
 437
 438         for (version = 1; version < 3; version++) {
 439                 tab = idtab_lookup(version);
 440                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 441                         nxt = TAILQ_NEXT(id, next);
 442                         if (id->death == 0)
 443                                 continue;
 444                         if (now >= id->death) {
 445                                 debug("expiring key '%s'", id->comment);
 446                                 TAILQ_REMOVE(&tab->idlist, id, next);
 447                                 free_identity(id);
 448                                 tab->nentries--;
 449                         } else
 450                                 deadline = (deadline == 0) ? id->death :
 451                                     MIN(deadline, id->death);
 452                 }
 453         }
 454         if (deadline == 0 || deadline <= now)
 455                 return 0;
 456         else
 457                 return (deadline - now);
 458 }
 459
 460 static void
 461 process_add_identity(SocketEntry *e, int version)
 462 {
 463         Idtab *tab = idtab_lookup(version);
 464         Identity *id;
 465         int type, success = 0, death = 0, confirm = 0;
 466         char *type_name, *comment;
 467         Key *k = NULL;
 468
 469         switch (version) {
 470         case 1:
 471                 k = key_new_private(KEY_RSA1);
 472                 (void) buffer_get_int(&e->request);             /* ignored */
 473                 buffer_get_bignum(&e->request, k->rsa->n);
 474                 buffer_get_bignum(&e->request, k->rsa->e);
 475                 buffer_get_bignum(&e->request, k->rsa->d);
 476                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 477
 478                 /* SSH and SSL have p and q swapped */
 479                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 480                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 481
 482                 /* Generate additional parameters */
 483                 rsa_generate_additional_parameters(k->rsa);
 484                 break;
 485         case 2:
 486                 type_name = buffer_get_string(&e->request, NULL);
 487                 type = key_type_from_name(type_name);
 488                 xfree(type_name);
 489                 switch (type) {
 490                 case KEY_DSA:
 491                         k = key_new_private(type);
 492                         buffer_get_bignum2(&e->request, k->dsa->p);
 493                         buffer_get_bignum2(&e->request, k->dsa->q);
 494                         buffer_get_bignum2(&e->request, k->dsa->g);
 495                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 496                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 497                         break;
 498                 case KEY_RSA:
 499                         k = key_new_private(type);
 500                         buffer_get_bignum2(&e->request, k->rsa->n);
 501                         buffer_get_bignum2(&e->request, k->rsa->e);
 502                         buffer_get_bignum2(&e->request, k->rsa->d);
 503                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 504                         buffer_get_bignum2(&e->request, k->rsa->p);
 505                         buffer_get_bignum2(&e->request, k->rsa->q);
 506
 507                         /* Generate additional parameters */
 508                         rsa_generate_additional_parameters(k->rsa);
 509                         break;
 510                 default:
 511                         buffer_clear(&e->request);
 512                         goto send;
 513                 }
 514                 break;
 515         }
 516         /* enable blinding */
 517         switch (k->type) {
 518         case KEY_RSA:
 519         case KEY_RSA1:
 520                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 521                         error("process_add_identity: RSA_blinding_on failed");
 522                         key_free(k);
 523                         goto send;
 524                 }
 525                 break;
 526         }
 527         comment = buffer_get_string(&e->request, NULL);
 528         if (k == NULL) {
 529                 xfree(comment);
 530                 goto send;
 531         }
 532         while (buffer_len(&e->request)) {
 533                 switch ((type = buffer_get_char(&e->request))) {
 534                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 535                         death = time(NULL) + buffer_get_int(&e->request);
 536                         break;
 537                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 538                         confirm = 1;
 539                         break;
 540                 default:
 541                         error("process_add_identity: "
 542                             "Unknown constraint type %d", type);
 543                         xfree(comment);
 544                         key_free(k);
 545                         goto send;
 546                 }
 547         }
 548         success = 1;
 549         if (lifetime && !death)
 550                 death = time(NULL) + lifetime;
 551         if ((id = lookup_identity(k, version)) == NULL) {
 552                 id = xmalloc(sizeof(Identity));
 553                 id->key = k;
 554                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 555                 /* Increment the number of identities. */
 556                 tab->nentries++;
 557         } else {
 558                 key_free(k);
 559                 xfree(id->comment);
 560         }
 561         id->comment = comment;
 562         id->death = death;
 563         id->confirm = confirm;
 564 send:
 565         buffer_put_int(&e->output, 1);
 566         buffer_put_char(&e->output,
 567             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 568 }
 569
 570 /* XXX todo: encrypt sensitive data with passphrase */
 571 static void
 572 process_lock_agent(SocketEntry *e, int lock)
 573 {
 574         int success = 0;
 575         char *passwd;
 576
 577         passwd = buffer_get_string(&e->request, NULL);
 578         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 579                 locked = 0;
 580                 memset(lock_passwd, 0, strlen(lock_passwd));
 581                 xfree(lock_passwd);
 582                 lock_passwd = NULL;
 583                 success = 1;
 584         } else if (!locked && lock) {
 585                 locked = 1;
 586                 lock_passwd = xstrdup(passwd);
 587                 success = 1;
 588         }
 589         memset(passwd, 0, strlen(passwd));
 590         xfree(passwd);
 591
 592         buffer_put_int(&e->output, 1);
 593         buffer_put_char(&e->output,
 594             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 595 }
 596
 597 static void
 598 no_identities(SocketEntry *e, u_int type)
 599 {
 600         Buffer msg;
 601
 602         buffer_init(&msg);
 603         buffer_put_char(&msg,
 604             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 605             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 606         buffer_put_int(&msg, 0);
 607         buffer_put_int(&e->output, buffer_len(&msg));
 608         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 609         buffer_free(&msg);
 610 }
 611
 612 #ifdef SMARTCARD
 613 static void
 614 process_add_smartcard_key(SocketEntry *e)
 615 {
 616         char *sc_reader_id = NULL, *pin;
 617         int i, type, version, success = 0, death = 0, confirm = 0;
 618         Key **keys, *k;
 619         Identity *id;
 620         Idtab *tab;
 621
 622         sc_reader_id = buffer_get_string(&e->request, NULL);
 623         pin = buffer_get_string(&e->request, NULL);
 624
 625         while (buffer_len(&e->request)) {
 626                 switch ((type = buffer_get_char(&e->request))) {
 627                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 628                         death = time(NULL) + buffer_get_int(&e->request);
 629                         break;
 630                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 631                         confirm = 1;
 632                         break;
 633                 default:
 634                         error("process_add_smartcard_key: "
 635                             "Unknown constraint type %d", type);
 636                         xfree(sc_reader_id);
 637                         xfree(pin);
 638                         goto send;
 639                 }
 640         }
 641         if (lifetime && !death)
 642                 death = time(NULL) + lifetime;
 643
 644         keys = sc_get_keys(sc_reader_id, pin);
 645         xfree(sc_reader_id);
 646         xfree(pin);
 647
 648         if (keys == NULL || keys[0] == NULL) {
 649                 error("sc_get_keys failed");
 650                 goto send;
 651         }
 652         for (i = 0; keys[i] != NULL; i++) {
 653                 k = keys[i];
 654                 version = k->type == KEY_RSA1 ? 1 : 2;
 655                 tab = idtab_lookup(version);
 656                 if (lookup_identity(k, version) == NULL) {
 657                         id = xmalloc(sizeof(Identity));
 658                         id->key = k;
 659                         id->comment = sc_get_key_label(k);
 660                         id->death = death;
 661                         id->confirm = confirm;
 662                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 663                         tab->nentries++;
 664                         success = 1;
 665                 } else {
 666                         key_free(k);
 667                 }
 668                 keys[i] = NULL;
 669         }
 670         xfree(keys);
 671 send:
 672         buffer_put_int(&e->output, 1);
 673         buffer_put_char(&e->output,
 674             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 675 }
 676
 677 static void
 678 process_remove_smartcard_key(SocketEntry *e)
 679 {
 680         char *sc_reader_id = NULL, *pin;
 681         int i, version, success = 0;
 682         Key **keys, *k = NULL;
 683         Identity *id;
 684         Idtab *tab;
 685
 686         sc_reader_id = buffer_get_string(&e->request, NULL);
 687         pin = buffer_get_string(&e->request, NULL);
 688         keys = sc_get_keys(sc_reader_id, pin);
 689         xfree(sc_reader_id);
 690         xfree(pin);
 691
 692         if (keys == NULL || keys[0] == NULL) {
 693                 error("sc_get_keys failed");
 694                 goto send;
 695         }
 696         for (i = 0; keys[i] != NULL; i++) {
 697                 k = keys[i];
 698                 version = k->type == KEY_RSA1 ? 1 : 2;
 699                 if ((id = lookup_identity(k, version)) != NULL) {
 700                         tab = idtab_lookup(version);
 701                         TAILQ_REMOVE(&tab->idlist, id, next);
 702                         tab->nentries--;
 703                         free_identity(id);
 704                         success = 1;
 705                 }
 706                 key_free(k);
 707                 keys[i] = NULL;
 708         }
 709         xfree(keys);
 710 send:
 711         buffer_put_int(&e->output, 1);
 712         buffer_put_char(&e->output,
 713             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 714 }
 715 #endif /* SMARTCARD */
 716
 717 /* dispatch incoming messages */
 718
 719 static void
 720 process_message(SocketEntry *e)
 721 {
 722         u_int msg_len, type;
 723         u_char *cp;
 724
 725         if (buffer_len(&e->input) < 5)
 726                 return;         /* Incomplete message. */
 727         cp = buffer_ptr(&e->input);
 728         msg_len = get_u32(cp);
 729         if (msg_len > 256 * 1024) {
 730                 close_socket(e);
 731                 return;
 732         }
 733         if (buffer_len(&e->input) < msg_len + 4)
 734                 return;
 735
 736         /* move the current input to e->request */
 737         buffer_consume(&e->input, 4);
 738         buffer_clear(&e->request);
 739         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 740         buffer_consume(&e->input, msg_len);
 741         type = buffer_get_char(&e->request);
 742
 743         /* check wheter agent is locked */
 744         if (locked && type != SSH_AGENTC_UNLOCK) {
 745                 buffer_clear(&e->request);
 746                 switch (type) {
 747                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 748                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 749                         /* send empty lists */
 750                         no_identities(e, type);
 751                         break;
 752                 default:
 753                         /* send a fail message for all other request types */
 754                         buffer_put_int(&e->output, 1);
 755                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 756                 }
 757                 return;
 758         }
 759
 760         debug("type %d", type);
 761         switch (type) {
 762         case SSH_AGENTC_LOCK:
 763         case SSH_AGENTC_UNLOCK:
 764                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 765                 break;
 766         /* ssh1 */
 767         case SSH_AGENTC_RSA_CHALLENGE:
 768                 process_authentication_challenge1(e);
 769                 break;
 770         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 771                 process_request_identities(e, 1);
 772                 break;
 773         case SSH_AGENTC_ADD_RSA_IDENTITY:
 774         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 775                 process_add_identity(e, 1);
 776                 break;
 777         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 778                 process_remove_identity(e, 1);
 779                 break;
 780         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 781                 process_remove_all_identities(e, 1);
 782                 break;
 783         /* ssh2 */
 784         case SSH2_AGENTC_SIGN_REQUEST:
 785                 process_sign_request2(e);
 786                 break;
 787         case SSH2_AGENTC_REQUEST_IDENTITIES:
 788                 process_request_identities(e, 2);
 789                 break;
 790         case SSH2_AGENTC_ADD_IDENTITY:
 791         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 792                 process_add_identity(e, 2);
 793                 break;
 794         case SSH2_AGENTC_REMOVE_IDENTITY:
 795                 process_remove_identity(e, 2);
 796                 break;
 797         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 798                 process_remove_all_identities(e, 2);
 799                 break;
 800 #ifdef SMARTCARD
 801         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 802         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 803                 process_add_smartcard_key(e);
 804                 break;
 805         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 806                 process_remove_smartcard_key(e);
 807                 break;
 808 #endif /* SMARTCARD */
 809         default:
 810                 /* Unknown message.  Respond with failure. */
 811                 error("Unknown message %d", type);
 812                 buffer_clear(&e->request);
 813                 buffer_put_int(&e->output, 1);
 814                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 815                 break;
 816         }
 817 }
 818
 819 static void
 820 new_socket(sock_type type, int fd)
 821 {
 822         u_int i, old_alloc, new_alloc;
 823
 824         set_nonblock(fd);
 825
 826         if (fd > max_fd)
 827                 max_fd = fd;
 828
 829         for (i = 0; i < sockets_alloc; i++)
 830                 if (sockets[i].type == AUTH_UNUSED) {
 831                         sockets[i].fd = fd;
 832                         buffer_init(&sockets[i].input);
 833                         buffer_init(&sockets[i].output);
 834                         buffer_init(&sockets[i].request);
 835                         sockets[i].type = type;
 836                         return;
 837                 }
 838         old_alloc = sockets_alloc;
 839         new_alloc = sockets_alloc + 10;
 840         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 841         for (i = old_alloc; i < new_alloc; i++)
 842                 sockets[i].type = AUTH_UNUSED;
 843         sockets_alloc = new_alloc;
 844         sockets[old_alloc].fd = fd;
 845         buffer_init(&sockets[old_alloc].input);
 846         buffer_init(&sockets[old_alloc].output);
 847         buffer_init(&sockets[old_alloc].request);
 848         sockets[old_alloc].type = type;
 849 }
 850
 851 static int
 852 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
 853     struct timeval **tvpp)
 854 {
 855         u_int i, sz, deadline;
 856         int n = 0;
 857         static struct timeval tv;
 858
 859         for (i = 0; i < sockets_alloc; i++) {
 860                 switch (sockets[i].type) {
 861                 case AUTH_SOCKET:
 862                 case AUTH_CONNECTION:
 863                         n = MAX(n, sockets[i].fd);
 864                         break;
 865                 case AUTH_UNUSED:
 866                         break;
 867                 default:
 868                         fatal("Unknown socket type %d", sockets[i].type);
 869                         break;
 870                 }
 871         }
 872
 873         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 874         if (*fdrp == NULL || sz > *nallocp) {
 875                 if (*fdrp)
 876                         xfree(*fdrp);
 877                 if (*fdwp)
 878                         xfree(*fdwp);
 879                 *fdrp = xmalloc(sz);
 880                 *fdwp = xmalloc(sz);
 881                 *nallocp = sz;
 882         }
 883         if (n < *fdl)
 884                 debug("XXX shrink: %d < %d", n, *fdl);
 885         *fdl = n;
 886         memset(*fdrp, 0, sz);
 887         memset(*fdwp, 0, sz);
 888
 889         for (i = 0; i < sockets_alloc; i++) {
 890                 switch (sockets[i].type) {
 891                 case AUTH_SOCKET:
 892                 case AUTH_CONNECTION:
 893                         FD_SET(sockets[i].fd, *fdrp);
 894                         if (buffer_len(&sockets[i].output) > 0)
 895                                 FD_SET(sockets[i].fd, *fdwp);
 896                         break;
 897                 default:
 898                         break;
 899                 }
 900         }
 901         deadline = reaper();
 902         if (parent_alive_interval != 0)
 903                 deadline = (deadline == 0) ? parent_alive_interval :
 904                     MIN(deadline, parent_alive_interval);
 905         if (deadline == 0) {
 906                 *tvpp = NULL;
 907         } else {
 908                 tv.tv_sec = deadline;
 909                 tv.tv_usec = 0;
 910                 *tvpp = &tv;
 911         }
 912         return (1);
 913 }
 914
 915 static void
 916 after_select(fd_set *readset, fd_set *writeset)
 917 {
 918         struct sockaddr_un sunaddr;
 919         socklen_t slen;
 920         char buf[1024];
 921         int len, sock;
 922         u_int i;
 923         uid_t euid;
 924         gid_t egid;
 925
 926         for (i = 0; i < sockets_alloc; i++)
 927                 switch (sockets[i].type) {
 928                 case AUTH_UNUSED:
 929                         break;
 930                 case AUTH_SOCKET:
 931                         if (FD_ISSET(sockets[i].fd, readset)) {
 932                                 slen = sizeof(sunaddr);
 933                                 sock = accept(sockets[i].fd,
 934                                     (struct sockaddr *)&sunaddr, &slen);
 935                                 if (sock < 0) {
 936                                         error("accept from AUTH_SOCKET: %s",
 937                                             strerror(errno));
 938                                         break;
 939                                 }
 940                                 if (getpeereid(sock, &euid, &egid) < 0) {
 941                                         error("getpeereid %d failed: %s",
 942                                             sock, strerror(errno));
 943                                         close(sock);
 944                                         break;
 945                                 }
 946                                 if ((euid != 0) && (getuid() != euid)) {
 947                                         error("uid mismatch: "
 948                                             "peer euid %u != uid %u",
 949                                             (u_int) euid, (u_int) getuid());
 950                                         close(sock);
 951                                         break;
 952                                 }
 953                                 new_socket(AUTH_CONNECTION, sock);
 954                         }
 955                         break;
 956                 case AUTH_CONNECTION:
 957                         if (buffer_len(&sockets[i].output) > 0 &&
 958                             FD_ISSET(sockets[i].fd, writeset)) {
 959                                 do {
 960                                         len = write(sockets[i].fd,
 961                                             buffer_ptr(&sockets[i].output),
 962                                             buffer_len(&sockets[i].output));
 963                                         if (len == -1 && (errno == EAGAIN ||
 964                                             errno == EINTR ||
 965                                             errno == EWOULDBLOCK))
 966                                                 continue;
 967                                         break;
 968                                 } while (1);
 969                                 if (len <= 0) {
 970                                         close_socket(&sockets[i]);
 971                                         break;
 972                                 }
 973                                 buffer_consume(&sockets[i].output, len);
 974                         }
 975                         if (FD_ISSET(sockets[i].fd, readset)) {
 976                                 do {
 977                                         len = read(sockets[i].fd, buf, sizeof(buf));
 978                                         if (len == -1 && (errno == EAGAIN ||
 979                                             errno == EINTR ||
 980                                             errno == EWOULDBLOCK))
 981                                                 continue;
 982                                         break;
 983                                 } while (1);
 984                                 if (len <= 0) {
 985                                         close_socket(&sockets[i]);
 986                                         break;
 987                                 }
 988                                 buffer_append(&sockets[i].input, buf, len);
 989                                 process_message(&sockets[i]);
 990                         }
 991                         break;
 992                 default:
 993                         fatal("Unknown type %d", sockets[i].type);
 994                 }
 995 }
 996
 997 static void
 998 cleanup_socket(void)
 999 {
1000         if (socket_name[0])
1001                 unlink(socket_name);
1002         if (socket_dir[0])
1003                 rmdir(socket_dir);
1004 }
1005
1006 void
1007 cleanup_exit(int i)
1008 {
1009         cleanup_socket();
1010         _exit(i);
1011 }
1012
1013 /*ARGSUSED*/
1014 static void
1015 cleanup_handler(int sig)
1016 {
1017         cleanup_socket();
1018         _exit(2);
1019 }
1020
1021 static void
1022 check_parent_exists(void)
1023 {
1024         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
1025                 /* printf("Parent has died - Authentication agent exiting.\n"); */
1026                 cleanup_socket();
1027                 _exit(2);
1028         }
1029 }
1030
1031 static void
1032 usage(void)
1033 {
1034         fprintf(stderr, "usage: %s [options] [command [arg ...]]\n",
1035             __progname);
1036         fprintf(stderr, "Options:\n");
1037         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1038         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1039         fprintf(stderr, "  -k          Kill the current agent.\n");
1040         fprintf(stderr, "  -d          Debug mode.\n");
1041         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1042         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1043         exit(1);
1044 }
1045
1046 int
1047 main(int ac, char **av)
1048 {
1049         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1050         int sock, fd, ch, result, saved_errno;
1051         u_int nalloc;
1052         char *shell, *format, *pidstr, *agentsocket = NULL;
1053         fd_set *readsetp = NULL, *writesetp = NULL;
1054         struct sockaddr_un sunaddr;
1055 #ifdef HAVE_SETRLIMIT
1056         struct rlimit rlim;
1057 #endif
1058         int prev_mask;
1059         extern int optind;
1060         extern char *optarg;
1061         pid_t pid;
1062         char pidstrbuf[1 + 3 * sizeof pid];
1063         struct timeval *tvp = NULL;
1064         size_t len;
1065
1066         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1067         sanitise_stdfd();
1068
1069         /* drop */
1070         setegid(getgid());
1071         setgid(getgid());
1072
1073 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1074         /* Disable ptrace on Linux without sgid bit */
1075         prctl(PR_SET_DUMPABLE, 0);
1076 #endif
1077
1078         SSLeay_add_all_algorithms();
1079
1080         __progname = ssh_get_progname(av[0]);
1081         init_rng();
1082         seed_rng();
1083
1084         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1085                 switch (ch) {
1086                 case 'c':
1087                         if (s_flag)
1088                                 usage();
1089                         c_flag++;
1090                         break;
1091                 case 'k':
1092                         k_flag++;
1093                         break;
1094                 case 's':
1095                         if (c_flag)
1096                                 usage();
1097                         s_flag++;
1098                         break;
1099                 case 'd':
1100                         if (d_flag)
1101                                 usage();
1102                         d_flag++;
1103                         break;
1104                 case 'a':
1105                         agentsocket = optarg;
1106                         break;
1107                 case 't':
1108                         if ((lifetime = convtime(optarg)) == -1) {
1109                                 fprintf(stderr, "Invalid lifetime\n");
1110                                 usage();
1111                         }
1112                         break;
1113                 default:
1114                         usage();
1115                 }
1116         }
1117         ac -= optind;
1118         av += optind;
1119
1120         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1121                 usage();
1122
1123         if (ac == 0 && !c_flag && !s_flag) {
1124                 shell = getenv("SHELL");
1125                 if (shell != NULL && (len = strlen(shell)) > 2 &&
1126                     strncmp(shell + len - 3, "csh", 3) == 0)
1127                         c_flag = 1;
1128         }
1129         if (k_flag) {
1130                 const char *errstr = NULL;
1131
1132                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1133                 if (pidstr == NULL) {
1134                         fprintf(stderr, "%s not set, cannot kill agent\n",
1135                             SSH_AGENTPID_ENV_NAME);
1136                         exit(1);
1137                 }
1138                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1139                 if (errstr) {
1140                         fprintf(stderr,
1141                             "%s=\"%s\", which is not a good PID: %s\n",
1142                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1143                         exit(1);
1144                 }
1145                 if (kill(pid, SIGTERM) == -1) {
1146                         perror("kill");
1147                         exit(1);
1148                 }
1149                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1150                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1151                 printf(format, SSH_AGENTPID_ENV_NAME);
1152                 printf("echo Agent pid %ld killed;\n", (long)pid);
1153                 exit(0);
1154         }
1155         parent_pid = getpid();
1156
1157         if (agentsocket == NULL) {
1158                 /* Create private directory for agent socket */
1159                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1160                 if (mkdtemp(socket_dir) == NULL) {
1161                         perror("mkdtemp: private socket dir");
1162                         exit(1);
1163                 }
1164                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1165                     (long)parent_pid);
1166         } else {
1167                 /* Try to use specified agent socket */
1168                 socket_dir[0] = '\0';
1169                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1170         }
1171
1172         /*
1173          * Create socket early so it will exist before command gets run from
1174          * the parent.
1175          */
1176         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1177         if (sock < 0) {
1178                 perror("socket");
1179                 *socket_name = '\0'; /* Don't unlink any existing file */
1180                 cleanup_exit(1);
1181         }
1182         memset(&sunaddr, 0, sizeof(sunaddr));
1183         sunaddr.sun_family = AF_UNIX;
1184         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1185         prev_mask = umask(0177);
1186         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1187                 perror("bind");
1188                 *socket_name = '\0'; /* Don't unlink any existing file */
1189                 umask(prev_mask);
1190                 cleanup_exit(1);
1191         }
1192         umask(prev_mask);
1193         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1194                 perror("listen");
1195                 cleanup_exit(1);
1196         }
1197
1198         /*
1199          * Fork, and have the parent execute the command, if any, or present
1200          * the socket data.  The child continues as the authentication agent.
1201          */
1202         if (d_flag) {
1203                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1204                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1205                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1206                     SSH_AUTHSOCKET_ENV_NAME);
1207                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1208                 goto skip;
1209         }
1210         pid = fork();
1211         if (pid == -1) {
1212                 perror("fork");
1213                 cleanup_exit(1);
1214         }
1215         if (pid != 0) {         /* Parent - execute the given command. */
1216                 close(sock);
1217                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1218                 if (ac == 0) {
1219                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1220                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1221                             SSH_AUTHSOCKET_ENV_NAME);
1222                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1223                             SSH_AGENTPID_ENV_NAME);
1224                         printf("echo Agent pid %ld;\n", (long)pid);
1225                         exit(0);
1226                 }
1227                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1228                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1229                         perror("setenv");
1230                         exit(1);
1231                 }
1232                 execvp(av[0], av);
1233                 perror(av[0]);
1234                 exit(1);
1235         }
1236         /* child */
1237         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1238
1239         if (setsid() == -1) {
1240                 error("setsid: %s", strerror(errno));
1241                 cleanup_exit(1);
1242         }
1243
1244         (void)chdir("/");
1245         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1246                 /* XXX might close listen socket */
1247                 (void)dup2(fd, STDIN_FILENO);
1248                 (void)dup2(fd, STDOUT_FILENO);
1249                 (void)dup2(fd, STDERR_FILENO);
1250                 if (fd > 2)
1251                         close(fd);
1252         }
1253
1254 #ifdef HAVE_SETRLIMIT
1255         /* deny core dumps, since memory contains unencrypted private keys */
1256         rlim.rlim_cur = rlim.rlim_max = 0;
1257         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1258                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1259                 cleanup_exit(1);
1260         }
1261 #endif
1262
1263 skip:
1264         new_socket(AUTH_SOCKET, sock);
1265         if (ac > 0)
1266                 parent_alive_interval = 10;
1267         idtab_init();
1268         if (!d_flag)
1269                 signal(SIGINT, SIG_IGN);
1270         signal(SIGPIPE, SIG_IGN);
1271         signal(SIGHUP, cleanup_handler);
1272         signal(SIGTERM, cleanup_handler);
1273         nalloc = 0;
1274
1275         while (1) {
1276                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1277                 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1278                 saved_errno = errno;
1279                 if (parent_alive_interval != 0)
1280                         check_parent_exists();
1281                 (void) reaper();        /* remove expired keys */
1282                 if (result < 0) {
1283                         if (saved_errno == EINTR)
1284                                 continue;
1285                         fatal("select: %s", strerror(saved_errno));
1286                 } else if (result > 0)
1287                         after_select(readsetp, writesetp);
1288         }
1289         /* NOTREACHED */
1290 }