openssh/ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.155 2007/03/19 12:16:42 dtucker 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
  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 "pathnames.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 ok = -1, flags;
 316         Buffer msg;
 317         Key *key;
 318
 319         datafellows = 0;
 320
 321         blob = buffer_get_string(&e->request, &blen);
 322         data = buffer_get_string(&e->request, &dlen);
 323
 324         flags = buffer_get_int(&e->request);
 325         if (flags & SSH_AGENT_OLD_SIGNATURE)
 326                 datafellows = SSH_BUG_SIGBLOB;
 327
 328         key = key_from_blob(blob, blen);
 329         if (key != NULL) {
 330                 Identity *id = lookup_identity(key, 2);
 331                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 332                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 333                 key_free(key);
 334         }
 335         buffer_init(&msg);
 336         if (ok == 0) {
 337                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 338                 buffer_put_string(&msg, signature, slen);
 339         } else {
 340                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 341         }
 342         buffer_put_int(&e->output, buffer_len(&msg));
 343         buffer_append(&e->output, buffer_ptr(&msg),
 344             buffer_len(&msg));
 345         buffer_free(&msg);
 346         xfree(data);
 347         xfree(blob);
 348         if (signature != NULL)
 349                 xfree(signature);
 350 }
 351
 352 /* shared */
 353 static void
 354 process_remove_identity(SocketEntry *e, int version)
 355 {
 356         u_int blen, bits;
 357         int success = 0;
 358         Key *key = NULL;
 359         u_char *blob;
 360
 361         switch (version) {
 362         case 1:
 363                 key = key_new(KEY_RSA1);
 364                 bits = buffer_get_int(&e->request);
 365                 buffer_get_bignum(&e->request, key->rsa->e);
 366                 buffer_get_bignum(&e->request, key->rsa->n);
 367
 368                 if (bits != key_size(key))
 369                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 370                             key_size(key), bits);
 371                 break;
 372         case 2:
 373                 blob = buffer_get_string(&e->request, &blen);
 374                 key = key_from_blob(blob, blen);
 375                 xfree(blob);
 376                 break;
 377         }
 378         if (key != NULL) {
 379                 Identity *id = lookup_identity(key, version);
 380                 if (id != NULL) {
 381                         /*
 382                          * We have this key.  Free the old key.  Since we
 383                          * don't want to leave empty slots in the middle of
 384                          * the array, we actually free the key there and move
 385                          * all the entries between the empty slot and the end
 386                          * of the array.
 387                          */
 388                         Idtab *tab = idtab_lookup(version);
 389                         if (tab->nentries < 1)
 390                                 fatal("process_remove_identity: "
 391                                     "internal error: tab->nentries %d",
 392                                     tab->nentries);
 393                         TAILQ_REMOVE(&tab->idlist, id, next);
 394                         free_identity(id);
 395                         tab->nentries--;
 396                         success = 1;
 397                 }
 398                 key_free(key);
 399         }
 400         buffer_put_int(&e->output, 1);
 401         buffer_put_char(&e->output,
 402             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 403 }
 404
 405 static void
 406 process_remove_all_identities(SocketEntry *e, int version)
 407 {
 408         Idtab *tab = idtab_lookup(version);
 409         Identity *id;
 410
 411         /* Loop over all identities and clear the keys. */
 412         for (id = TAILQ_FIRST(&tab->idlist); id;
 413             id = TAILQ_FIRST(&tab->idlist)) {
 414                 TAILQ_REMOVE(&tab->idlist, id, next);
 415                 free_identity(id);
 416         }
 417
 418         /* Mark that there are no identities. */
 419         tab->nentries = 0;
 420
 421         /* Send success. */
 422         buffer_put_int(&e->output, 1);
 423         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 424 }
 425
 426 /* removes expired keys and returns number of seconds until the next expiry */
 427 static u_int
 428 reaper(void)
 429 {
 430         u_int deadline = 0, now = time(NULL);
 431         Identity *id, *nxt;
 432         int version;
 433         Idtab *tab;
 434
 435         for (version = 1; version < 3; version++) {
 436                 tab = idtab_lookup(version);
 437                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 438                         nxt = TAILQ_NEXT(id, next);
 439                         if (id->death == 0)
 440                                 continue;
 441                         if (now >= id->death) {
 442                                 debug("expiring key '%s'", id->comment);
 443                                 TAILQ_REMOVE(&tab->idlist, id, next);
 444                                 free_identity(id);
 445                                 tab->nentries--;
 446                         } else
 447                                 deadline = (deadline == 0) ? id->death :
 448                                     MIN(deadline, id->death);
 449                 }
 450         }
 451         if (deadline == 0 || deadline <= now)
 452                 return 0;
 453         else
 454                 return (deadline - now);
 455 }
 456
 457 static void
 458 process_add_identity(SocketEntry *e, int version)
 459 {
 460         Idtab *tab = idtab_lookup(version);
 461         int type, success = 0, death = 0, confirm = 0;
 462         char *type_name, *comment;
 463         Key *k = NULL;
 464
 465         switch (version) {
 466         case 1:
 467                 k = key_new_private(KEY_RSA1);
 468                 (void) buffer_get_int(&e->request);             /* ignored */
 469                 buffer_get_bignum(&e->request, k->rsa->n);
 470                 buffer_get_bignum(&e->request, k->rsa->e);
 471                 buffer_get_bignum(&e->request, k->rsa->d);
 472                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 473
 474                 /* SSH and SSL have p and q swapped */
 475                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 476                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 477
 478                 /* Generate additional parameters */
 479                 rsa_generate_additional_parameters(k->rsa);
 480                 break;
 481         case 2:
 482                 type_name = buffer_get_string(&e->request, NULL);
 483                 type = key_type_from_name(type_name);
 484                 xfree(type_name);
 485                 switch (type) {
 486                 case KEY_DSA:
 487                         k = key_new_private(type);
 488                         buffer_get_bignum2(&e->request, k->dsa->p);
 489                         buffer_get_bignum2(&e->request, k->dsa->q);
 490                         buffer_get_bignum2(&e->request, k->dsa->g);
 491                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 492                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 493                         break;
 494                 case KEY_RSA:
 495                         k = key_new_private(type);
 496                         buffer_get_bignum2(&e->request, k->rsa->n);
 497                         buffer_get_bignum2(&e->request, k->rsa->e);
 498                         buffer_get_bignum2(&e->request, k->rsa->d);
 499                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 500                         buffer_get_bignum2(&e->request, k->rsa->p);
 501                         buffer_get_bignum2(&e->request, k->rsa->q);
 502
 503                         /* Generate additional parameters */
 504                         rsa_generate_additional_parameters(k->rsa);
 505                         break;
 506                 default:
 507                         buffer_clear(&e->request);
 508                         goto send;
 509                 }
 510                 break;
 511         }
 512         /* enable blinding */
 513         switch (k->type) {
 514         case KEY_RSA:
 515         case KEY_RSA1:
 516                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 517                         error("process_add_identity: RSA_blinding_on failed");
 518                         key_free(k);
 519                         goto send;
 520                 }
 521                 break;
 522         }
 523         comment = buffer_get_string(&e->request, NULL);
 524         if (k == NULL) {
 525                 xfree(comment);
 526                 goto send;
 527         }
 528         success = 1;
 529         while (buffer_len(&e->request)) {
 530                 switch (buffer_get_char(&e->request)) {
 531                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 532                         death = time(NULL) + buffer_get_int(&e->request);
 533                         break;
 534                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 535                         confirm = 1;
 536                         break;
 537                 default:
 538                         break;
 539                 }
 540         }
 541         if (lifetime && !death)
 542                 death = time(NULL) + lifetime;
 543         if (lookup_identity(k, version) == NULL) {
 544                 Identity *id = xmalloc(sizeof(Identity));
 545                 id->key = k;
 546                 id->comment = comment;
 547                 id->death = death;
 548                 id->confirm = confirm;
 549                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 550                 /* Increment the number of identities. */
 551                 tab->nentries++;
 552         } else {
 553                 key_free(k);
 554                 xfree(comment);
 555         }
 556 send:
 557         buffer_put_int(&e->output, 1);
 558         buffer_put_char(&e->output,
 559             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 560 }
 561
 562 /* XXX todo: encrypt sensitive data with passphrase */
 563 static void
 564 process_lock_agent(SocketEntry *e, int lock)
 565 {
 566         int success = 0;
 567         char *passwd;
 568
 569         passwd = buffer_get_string(&e->request, NULL);
 570         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 571                 locked = 0;
 572                 memset(lock_passwd, 0, strlen(lock_passwd));
 573                 xfree(lock_passwd);
 574                 lock_passwd = NULL;
 575                 success = 1;
 576         } else if (!locked && lock) {
 577                 locked = 1;
 578                 lock_passwd = xstrdup(passwd);
 579                 success = 1;
 580         }
 581         memset(passwd, 0, strlen(passwd));
 582         xfree(passwd);
 583
 584         buffer_put_int(&e->output, 1);
 585         buffer_put_char(&e->output,
 586             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 587 }
 588
 589 static void
 590 no_identities(SocketEntry *e, u_int type)
 591 {
 592         Buffer msg;
 593
 594         buffer_init(&msg);
 595         buffer_put_char(&msg,
 596             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 597             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 598         buffer_put_int(&msg, 0);
 599         buffer_put_int(&e->output, buffer_len(&msg));
 600         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 601         buffer_free(&msg);
 602 }
 603
 604 #ifdef SMARTCARD
 605 static void
 606 process_add_smartcard_key (SocketEntry *e)
 607 {
 608         char *sc_reader_id = NULL, *pin;
 609         int i, version, success = 0, death = 0, confirm = 0;
 610         Key **keys, *k;
 611         Identity *id;
 612         Idtab *tab;
 613
 614         sc_reader_id = buffer_get_string(&e->request, NULL);
 615         pin = buffer_get_string(&e->request, NULL);
 616
 617         while (buffer_len(&e->request)) {
 618                 switch (buffer_get_char(&e->request)) {
 619                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 620                         death = time(NULL) + buffer_get_int(&e->request);
 621                         break;
 622                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 623                         confirm = 1;
 624                         break;
 625                 default:
 626                         break;
 627                 }
 628         }
 629         if (lifetime && !death)
 630                 death = time(NULL) + lifetime;
 631
 632         keys = sc_get_keys(sc_reader_id, pin);
 633         xfree(sc_reader_id);
 634         xfree(pin);
 635
 636         if (keys == NULL || keys[0] == NULL) {
 637                 error("sc_get_keys failed");
 638                 goto send;
 639         }
 640         for (i = 0; keys[i] != NULL; i++) {
 641                 k = keys[i];
 642                 version = k->type == KEY_RSA1 ? 1 : 2;
 643                 tab = idtab_lookup(version);
 644                 if (lookup_identity(k, version) == NULL) {
 645                         id = xmalloc(sizeof(Identity));
 646                         id->key = k;
 647                         id->comment = sc_get_key_label(k);
 648                         id->death = death;
 649                         id->confirm = confirm;
 650                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 651                         tab->nentries++;
 652                         success = 1;
 653                 } else {
 654                         key_free(k);
 655                 }
 656                 keys[i] = NULL;
 657         }
 658         xfree(keys);
 659 send:
 660         buffer_put_int(&e->output, 1);
 661         buffer_put_char(&e->output,
 662             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 663 }
 664
 665 static void
 666 process_remove_smartcard_key(SocketEntry *e)
 667 {
 668         char *sc_reader_id = NULL, *pin;
 669         int i, version, success = 0;
 670         Key **keys, *k = NULL;
 671         Identity *id;
 672         Idtab *tab;
 673
 674         sc_reader_id = buffer_get_string(&e->request, NULL);
 675         pin = buffer_get_string(&e->request, NULL);
 676         keys = sc_get_keys(sc_reader_id, pin);
 677         xfree(sc_reader_id);
 678         xfree(pin);
 679
 680         if (keys == NULL || keys[0] == NULL) {
 681                 error("sc_get_keys failed");
 682                 goto send;
 683         }
 684         for (i = 0; keys[i] != NULL; i++) {
 685                 k = keys[i];
 686                 version = k->type == KEY_RSA1 ? 1 : 2;
 687                 if ((id = lookup_identity(k, version)) != NULL) {
 688                         tab = idtab_lookup(version);
 689                         TAILQ_REMOVE(&tab->idlist, id, next);
 690                         tab->nentries--;
 691                         free_identity(id);
 692                         success = 1;
 693                 }
 694                 key_free(k);
 695                 keys[i] = NULL;
 696         }
 697         xfree(keys);
 698 send:
 699         buffer_put_int(&e->output, 1);
 700         buffer_put_char(&e->output,
 701             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 702 }
 703 #endif /* SMARTCARD */
 704
 705 /* dispatch incoming messages */
 706
 707 static void
 708 process_message(SocketEntry *e)
 709 {
 710         u_int msg_len, type;
 711         u_char *cp;
 712
 713         if (buffer_len(&e->input) < 5)
 714                 return;         /* Incomplete message. */
 715         cp = buffer_ptr(&e->input);
 716         msg_len = get_u32(cp);
 717         if (msg_len > 256 * 1024) {
 718                 close_socket(e);
 719                 return;
 720         }
 721         if (buffer_len(&e->input) < msg_len + 4)
 722                 return;
 723
 724         /* move the current input to e->request */
 725         buffer_consume(&e->input, 4);
 726         buffer_clear(&e->request);
 727         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 728         buffer_consume(&e->input, msg_len);
 729         type = buffer_get_char(&e->request);
 730
 731         /* check wheter agent is locked */
 732         if (locked && type != SSH_AGENTC_UNLOCK) {
 733                 buffer_clear(&e->request);
 734                 switch (type) {
 735                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 736                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 737                         /* send empty lists */
 738                         no_identities(e, type);
 739                         break;
 740                 default:
 741                         /* send a fail message for all other request types */
 742                         buffer_put_int(&e->output, 1);
 743                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 744                 }
 745                 return;
 746         }
 747
 748         debug("type %d", type);
 749         switch (type) {
 750         case SSH_AGENTC_LOCK:
 751         case SSH_AGENTC_UNLOCK:
 752                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 753                 break;
 754         /* ssh1 */
 755         case SSH_AGENTC_RSA_CHALLENGE:
 756                 process_authentication_challenge1(e);
 757                 break;
 758         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 759                 process_request_identities(e, 1);
 760                 break;
 761         case SSH_AGENTC_ADD_RSA_IDENTITY:
 762         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 763                 process_add_identity(e, 1);
 764                 break;
 765         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 766                 process_remove_identity(e, 1);
 767                 break;
 768         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 769                 process_remove_all_identities(e, 1);
 770                 break;
 771         /* ssh2 */
 772         case SSH2_AGENTC_SIGN_REQUEST:
 773                 process_sign_request2(e);
 774                 break;
 775         case SSH2_AGENTC_REQUEST_IDENTITIES:
 776                 process_request_identities(e, 2);
 777                 break;
 778         case SSH2_AGENTC_ADD_IDENTITY:
 779         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 780                 process_add_identity(e, 2);
 781                 break;
 782         case SSH2_AGENTC_REMOVE_IDENTITY:
 783                 process_remove_identity(e, 2);
 784                 break;
 785         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 786                 process_remove_all_identities(e, 2);
 787                 break;
 788 #ifdef SMARTCARD
 789         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 790         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 791                 process_add_smartcard_key(e);
 792                 break;
 793         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 794                 process_remove_smartcard_key(e);
 795                 break;
 796 #endif /* SMARTCARD */
 797         default:
 798                 /* Unknown message.  Respond with failure. */
 799                 error("Unknown message %d", type);
 800                 buffer_clear(&e->request);
 801                 buffer_put_int(&e->output, 1);
 802                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 803                 break;
 804         }
 805 }
 806
 807 static void
 808 new_socket(sock_type type, int fd)
 809 {
 810         u_int i, old_alloc, new_alloc;
 811
 812         set_nonblock(fd);
 813
 814         if (fd > max_fd)
 815                 max_fd = fd;
 816
 817         for (i = 0; i < sockets_alloc; i++)
 818                 if (sockets[i].type == AUTH_UNUSED) {
 819                         sockets[i].fd = fd;
 820                         buffer_init(&sockets[i].input);
 821                         buffer_init(&sockets[i].output);
 822                         buffer_init(&sockets[i].request);
 823                         sockets[i].type = type;
 824                         return;
 825                 }
 826         old_alloc = sockets_alloc;
 827         new_alloc = sockets_alloc + 10;
 828         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 829         for (i = old_alloc; i < new_alloc; i++)
 830                 sockets[i].type = AUTH_UNUSED;
 831         sockets_alloc = new_alloc;
 832         sockets[old_alloc].fd = fd;
 833         buffer_init(&sockets[old_alloc].input);
 834         buffer_init(&sockets[old_alloc].output);
 835         buffer_init(&sockets[old_alloc].request);
 836         sockets[old_alloc].type = type;
 837 }
 838
 839 static int
 840 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
 841     struct timeval **tvpp)
 842 {
 843         u_int i, sz, deadline;
 844         int n = 0;
 845         static struct timeval tv;
 846
 847         for (i = 0; i < sockets_alloc; i++) {
 848                 switch (sockets[i].type) {
 849                 case AUTH_SOCKET:
 850                 case AUTH_CONNECTION:
 851                         n = MAX(n, sockets[i].fd);
 852                         break;
 853                 case AUTH_UNUSED:
 854                         break;
 855                 default:
 856                         fatal("Unknown socket type %d", sockets[i].type);
 857                         break;
 858                 }
 859         }
 860
 861         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 862         if (*fdrp == NULL || sz > *nallocp) {
 863                 if (*fdrp)
 864                         xfree(*fdrp);
 865                 if (*fdwp)
 866                         xfree(*fdwp);
 867                 *fdrp = xmalloc(sz);
 868                 *fdwp = xmalloc(sz);
 869                 *nallocp = sz;
 870         }
 871         if (n < *fdl)
 872                 debug("XXX shrink: %d < %d", n, *fdl);
 873         *fdl = n;
 874         memset(*fdrp, 0, sz);
 875         memset(*fdwp, 0, sz);
 876
 877         for (i = 0; i < sockets_alloc; i++) {
 878                 switch (sockets[i].type) {
 879                 case AUTH_SOCKET:
 880                 case AUTH_CONNECTION:
 881                         FD_SET(sockets[i].fd, *fdrp);
 882                         if (buffer_len(&sockets[i].output) > 0)
 883                                 FD_SET(sockets[i].fd, *fdwp);
 884                         break;
 885                 default:
 886                         break;
 887                 }
 888         }
 889         deadline = reaper();
 890         if (parent_alive_interval != 0)
 891                 deadline = (deadline == 0) ? parent_alive_interval :
 892                     MIN(deadline, parent_alive_interval);
 893         if (deadline == 0) {
 894                 *tvpp = NULL;
 895         } else {
 896                 tv.tv_sec = deadline;
 897                 tv.tv_usec = 0;
 898                 *tvpp = &tv;
 899         }
 900         return (1);
 901 }
 902
 903 static void
 904 after_select(fd_set *readset, fd_set *writeset)
 905 {
 906         struct sockaddr_un sunaddr;
 907         socklen_t slen;
 908         char buf[1024];
 909         int len, sock;
 910         u_int i;
 911         uid_t euid;
 912         gid_t egid;
 913
 914         for (i = 0; i < sockets_alloc; i++)
 915                 switch (sockets[i].type) {
 916                 case AUTH_UNUSED:
 917                         break;
 918                 case AUTH_SOCKET:
 919                         if (FD_ISSET(sockets[i].fd, readset)) {
 920                                 slen = sizeof(sunaddr);
 921                                 sock = accept(sockets[i].fd,
 922                                     (struct sockaddr *)&sunaddr, &slen);
 923                                 if (sock < 0) {
 924                                         error("accept from AUTH_SOCKET: %s",
 925                                             strerror(errno));
 926                                         break;
 927                                 }
 928                                 if (getpeereid(sock, &euid, &egid) < 0) {
 929                                         error("getpeereid %d failed: %s",
 930                                             sock, strerror(errno));
 931                                         close(sock);
 932                                         break;
 933                                 }
 934                                 if ((euid != 0) && (getuid() != euid)) {
 935                                         error("uid mismatch: "
 936                                             "peer euid %u != uid %u",
 937                                             (u_int) euid, (u_int) getuid());
 938                                         close(sock);
 939                                         break;
 940                                 }
 941                                 new_socket(AUTH_CONNECTION, sock);
 942                         }
 943                         break;
 944                 case AUTH_CONNECTION:
 945                         if (buffer_len(&sockets[i].output) > 0 &&
 946                             FD_ISSET(sockets[i].fd, writeset)) {
 947                                 do {
 948                                         len = write(sockets[i].fd,
 949                                             buffer_ptr(&sockets[i].output),
 950                                             buffer_len(&sockets[i].output));
 951                                         if (len == -1 && (errno == EAGAIN ||
 952                                             errno == EINTR))
 953                                                 continue;
 954                                         break;
 955                                 } while (1);
 956                                 if (len <= 0) {
 957                                         close_socket(&sockets[i]);
 958                                         break;
 959                                 }
 960                                 buffer_consume(&sockets[i].output, len);
 961                         }
 962                         if (FD_ISSET(sockets[i].fd, readset)) {
 963                                 do {
 964                                         len = read(sockets[i].fd, buf, sizeof(buf));
 965                                         if (len == -1 && (errno == EAGAIN ||
 966                                             errno == EINTR))
 967                                                 continue;
 968                                         break;
 969                                 } while (1);
 970                                 if (len <= 0) {
 971                                         close_socket(&sockets[i]);
 972                                         break;
 973                                 }
 974                                 buffer_append(&sockets[i].input, buf, len);
 975                                 process_message(&sockets[i]);
 976                         }
 977                         break;
 978                 default:
 979                         fatal("Unknown type %d", sockets[i].type);
 980                 }
 981 }
 982
 983 static void
 984 cleanup_socket(void)
 985 {
 986         if (socket_name[0])
 987                 unlink(socket_name);
 988         if (socket_dir[0])
 989                 rmdir(socket_dir);
 990 }
 991
 992 void
 993 cleanup_exit(int i)
 994 {
 995         cleanup_socket();
 996         _exit(i);
 997 }
 998
 999 /*ARGSUSED*/
1000 static void
1001 cleanup_handler(int sig)
1002 {
1003         cleanup_socket();
1004         _exit(2);
1005 }
1006
1007 static void
1008 check_parent_exists(void)
1009 {
1010         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
1011                 /* printf("Parent has died - Authentication agent exiting.\n"); */
1012                 cleanup_socket();
1013                 _exit(2);
1014         }
1015 }
1016
1017 static void
1018 usage(void)
1019 {
1020         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
1021             __progname);
1022         fprintf(stderr, "Options:\n");
1023         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1024         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1025         fprintf(stderr, "  -k          Kill the current agent.\n");
1026         fprintf(stderr, "  -d          Debug mode.\n");
1027         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1028         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1029         exit(1);
1030 }
1031
1032 int
1033 main(int ac, char **av)
1034 {
1035         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1036         int sock, fd, ch, result, saved_errno;
1037         u_int nalloc;
1038         char *shell, *format, *pidstr, *agentsocket = NULL;
1039         fd_set *readsetp = NULL, *writesetp = NULL;
1040         struct sockaddr_un sunaddr;
1041 #ifdef HAVE_SETRLIMIT
1042         struct rlimit rlim;
1043 #endif
1044         int prev_mask;
1045         extern int optind;
1046         extern char *optarg;
1047         pid_t pid;
1048         char pidstrbuf[1 + 3 * sizeof pid];
1049         struct timeval *tvp = NULL;
1050
1051         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1052         sanitise_stdfd();
1053
1054         /* drop */
1055         setegid(getgid());
1056         setgid(getgid());
1057
1058 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1059         /* Disable ptrace on Linux without sgid bit */
1060         prctl(PR_SET_DUMPABLE, 0);
1061 #endif
1062
1063         SSLeay_add_all_algorithms();
1064
1065         __progname = ssh_get_progname(av[0]);
1066         init_pathnames();
1067         init_rng();
1068         seed_rng();
1069
1070         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1071                 switch (ch) {
1072                 case 'c':
1073                         if (s_flag)
1074                                 usage();
1075                         c_flag++;
1076                         break;
1077                 case 'k':
1078                         k_flag++;
1079                         break;
1080                 case 's':
1081                         if (c_flag)
1082                                 usage();
1083                         s_flag++;
1084                         break;
1085                 case 'd':
1086                         if (d_flag)
1087                                 usage();
1088                         d_flag++;
1089                         break;
1090                 case 'a':
1091                         agentsocket = optarg;
1092                         break;
1093                 case 't':
1094                         if ((lifetime = convtime(optarg)) == -1) {
1095                                 fprintf(stderr, "Invalid lifetime\n");
1096                                 usage();
1097                         }
1098                         break;
1099                 default:
1100                         usage();
1101                 }
1102         }
1103         ac -= optind;
1104         av += optind;
1105
1106         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1107                 usage();
1108
1109         if (ac == 0 && !c_flag && !s_flag) {
1110                 shell = getenv("SHELL");
1111                 if (shell != NULL &&
1112                     strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1113                         c_flag = 1;
1114         }
1115         if (k_flag) {
1116                 const char *errstr = NULL;
1117
1118                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1119                 if (pidstr == NULL) {
1120                         fprintf(stderr, "%s not set, cannot kill agent\n",
1121                             SSH_AGENTPID_ENV_NAME);
1122                         exit(1);
1123                 }
1124                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1125                 if (errstr) {
1126                         fprintf(stderr,
1127                             "%s=\"%s\", which is not a good PID: %s\n",
1128                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1129                         exit(1);
1130                 }
1131                 if (kill(pid, SIGTERM) == -1) {
1132                         perror("kill");
1133                         exit(1);
1134                 }
1135                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1136                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1137                 printf(format, SSH_AGENTPID_ENV_NAME);
1138                 printf("echo Agent pid %ld killed;\n", (long)pid);
1139                 exit(0);
1140         }
1141         parent_pid = getpid();
1142
1143         if (agentsocket == NULL) {
1144                 /* Create private directory for agent socket */
1145                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1146                 if (mkdtemp(socket_dir) == NULL) {
1147                         perror("mkdtemp: private socket dir");
1148                         exit(1);
1149                 }
1150                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1151                     (long)parent_pid);
1152         } else {
1153                 /* Try to use specified agent socket */
1154                 socket_dir[0] = '\0';
1155                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1156         }
1157
1158         /*
1159          * Create socket early so it will exist before command gets run from
1160          * the parent.
1161          */
1162         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1163         if (sock < 0) {
1164                 perror("socket");
1165                 *socket_name = '\0'; /* Don't unlink any existing file */
1166                 cleanup_exit(1);
1167         }
1168         memset(&sunaddr, 0, sizeof(sunaddr));
1169         sunaddr.sun_family = AF_UNIX;
1170         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1171         prev_mask = umask(0177);
1172         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1173                 perror("bind");
1174                 *socket_name = '\0'; /* Don't unlink any existing file */
1175                 umask(prev_mask);
1176                 cleanup_exit(1);
1177         }
1178         umask(prev_mask);
1179         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1180                 perror("listen");
1181                 cleanup_exit(1);
1182         }
1183
1184         /*
1185          * Fork, and have the parent execute the command, if any, or present
1186          * the socket data.  The child continues as the authentication agent.
1187          */
1188         if (d_flag) {
1189                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1190                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1191                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1192                     SSH_AUTHSOCKET_ENV_NAME);
1193                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1194                 goto skip;
1195         }
1196         pid = fork();
1197         if (pid == -1) {
1198                 perror("fork");
1199                 cleanup_exit(1);
1200         }
1201         if (pid != 0) {         /* Parent - execute the given command. */
1202                 close(sock);
1203                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1204                 if (ac == 0) {
1205                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1206                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1207                             SSH_AUTHSOCKET_ENV_NAME);
1208                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1209                             SSH_AGENTPID_ENV_NAME);
1210                         printf("echo Agent pid %ld;\n", (long)pid);
1211                         exit(0);
1212                 }
1213                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1214                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1215                         perror("setenv");
1216                         exit(1);
1217                 }
1218                 execvp(av[0], av);
1219                 perror(av[0]);
1220                 exit(1);
1221         }
1222         /* child */
1223         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1224
1225         if (setsid() == -1) {
1226                 error("setsid: %s", strerror(errno));
1227                 cleanup_exit(1);
1228         }
1229
1230         (void)chdir("/");
1231         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1232                 /* XXX might close listen socket */
1233                 (void)dup2(fd, STDIN_FILENO);
1234                 (void)dup2(fd, STDOUT_FILENO);
1235                 (void)dup2(fd, STDERR_FILENO);
1236                 if (fd > 2)
1237                         close(fd);
1238         }
1239
1240 #ifdef HAVE_SETRLIMIT
1241         /* deny core dumps, since memory contains unencrypted private keys */
1242         rlim.rlim_cur = rlim.rlim_max = 0;
1243         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1244                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1245                 cleanup_exit(1);
1246         }
1247 #endif
1248
1249 skip:
1250         new_socket(AUTH_SOCKET, sock);
1251         if (ac > 0)
1252                 parent_alive_interval = 10;
1253         idtab_init();
1254         if (!d_flag)
1255                 signal(SIGINT, SIG_IGN);
1256         signal(SIGPIPE, SIG_IGN);
1257         signal(SIGHUP, cleanup_handler);
1258         signal(SIGTERM, cleanup_handler);
1259         nalloc = 0;
1260
1261         while (1) {
1262                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1263                 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1264                 saved_errno = errno;
1265                 if (parent_alive_interval != 0)
1266                         check_parent_exists();
1267                 (void) reaper();        /* remove expired keys */
1268                 if (result < 0) {
1269                         if (saved_errno == EINTR)
1270                                 continue;
1271                         fatal("select: %s", strerror(saved_errno));
1272                 } else if (result > 0)
1273                         after_select(readsetp, writesetp);
1274         }
1275         /* NOTREACHED */
1276 }