ssh-agent.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * The authentication agent program.
   6  *
   7  * As far as I am concerned, the code I have written for this software
   8  * can be used freely for any purpose.  Any derived versions of this
   9  * software must be clearly marked as such, and if the derived work is
  10  * incompatible with the protocol description in the RFC file, it must be
  11  * called by a name other than "ssh" or "Secure Shell".
  12  *
  13  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  14  *
  15  * Redistribution and use in source and binary forms, with or without
  16  * modification, are permitted provided that the following conditions
  17  * are met:
  18  * 1. Redistributions of source code must retain the above copyright
  19  *    notice, this list of conditions and the following disclaimer.
  20  * 2. Redistributions in binary form must reproduce the above copyright
  21  *    notice, this list of conditions and the following disclaimer in the
  22  *    documentation and/or other materials provided with the distribution.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  27  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  28  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  29  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  30  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  31  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  32  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  33  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 #include "includes.h"
  37 #include "openbsd-compat/sys-queue.h"
  38 RCSID("$OpenBSD: ssh-agent.c,v 1.126 2006/02/08 12:15:27 stevesk Exp $");
  39
  40 #ifdef HAVE_PATHS_H
  41 # include <paths.h>
  42 #endif
  43 #include <openssl/evp.h>
  44 #include <openssl/md5.h>
  45
  46 #include "ssh.h"
  47 #include "rsa.h"
  48 #include "buffer.h"
  49 #include "bufaux.h"
  50 #include "xmalloc.h"
  51 #include "getput.h"
  52 #include "key.h"
  53 #include "authfd.h"
  54 #include "compat.h"
  55 #include "log.h"
  56 #include "misc.h"
  57
  58 #ifdef SMARTCARD
  59 #include "scard.h"
  60 #endif
  61
  62 #if defined(HAVE_SYS_PRCTL_H)
  63 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  64 #endif
  65
  66 typedef enum {
  67         AUTH_UNUSED,
  68         AUTH_SOCKET,
  69         AUTH_CONNECTION
  70 } sock_type;
  71
  72 typedef struct {
  73         int fd;
  74         sock_type type;
  75         Buffer input;
  76         Buffer output;
  77         Buffer request;
  78 } SocketEntry;
  79
  80 u_int sockets_alloc = 0;
  81 SocketEntry *sockets = NULL;
  82
  83 typedef struct identity {
  84         TAILQ_ENTRY(identity) next;
  85         Key *key;
  86         char *comment;
  87         u_int death;
  88         u_int confirm;
  89 } Identity;
  90
  91 typedef struct {
  92         int nentries;
  93         TAILQ_HEAD(idqueue, identity) idlist;
  94 } Idtab;
  95
  96 /* private key table, one per protocol version */
  97 Idtab idtable[3];
  98
  99 int max_fd = 0;
 100
 101 /* pid of shell == parent of agent */
 102 pid_t parent_pid = -1;
 103
 104 /* pathname and directory for AUTH_SOCKET */
 105 char socket_name[1024];
 106 char socket_dir[1024];
 107
 108 /* locking */
 109 int locked = 0;
 110 char *lock_passwd = NULL;
 111
 112 extern char *__progname;
 113
 114 /* Default lifetime (0 == forever) */
 115 static int lifetime = 0;
 116
 117 static void
 118 close_socket(SocketEntry *e)
 119 {
 120         close(e->fd);
 121         e->fd = -1;
 122         e->type = AUTH_UNUSED;
 123         buffer_free(&e->input);
 124         buffer_free(&e->output);
 125         buffer_free(&e->request);
 126 }
 127
 128 static void
 129 idtab_init(void)
 130 {
 131         int i;
 132
 133         for (i = 0; i <=2; i++) {
 134                 TAILQ_INIT(&idtable[i].idlist);
 135                 idtable[i].nentries = 0;
 136         }
 137 }
 138
 139 /* return private key table for requested protocol version */
 140 static Idtab *
 141 idtab_lookup(int version)
 142 {
 143         if (version < 1 || version > 2)
 144                 fatal("internal error, bad protocol version %d", version);
 145         return &idtable[version];
 146 }
 147
 148 static void
 149 free_identity(Identity *id)
 150 {
 151         key_free(id->key);
 152         xfree(id->comment);
 153         xfree(id);
 154 }
 155
 156 /* return matching private key for given public key */
 157 static Identity *
 158 lookup_identity(Key *key, int version)
 159 {
 160         Identity *id;
 161
 162         Idtab *tab = idtab_lookup(version);
 163         TAILQ_FOREACH(id, &tab->idlist, next) {
 164                 if (key_equal(key, id->key))
 165                         return (id);
 166         }
 167         return (NULL);
 168 }
 169
 170 /* Check confirmation of keysign request */
 171 static int
 172 confirm_key(Identity *id)
 173 {
 174         char *p;
 175         int ret = -1;
 176
 177         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 178         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 179             id->comment, p))
 180                 ret = 0;
 181         xfree(p);
 182
 183         return (ret);
 184 }
 185
 186 /* send list of supported public keys to 'client' */
 187 static void
 188 process_request_identities(SocketEntry *e, int version)
 189 {
 190         Idtab *tab = idtab_lookup(version);
 191         Identity *id;
 192         Buffer msg;
 193
 194         buffer_init(&msg);
 195         buffer_put_char(&msg, (version == 1) ?
 196             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 197         buffer_put_int(&msg, tab->nentries);
 198         TAILQ_FOREACH(id, &tab->idlist, next) {
 199                 if (id->key->type == KEY_RSA1) {
 200                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 201                         buffer_put_bignum(&msg, id->key->rsa->e);
 202                         buffer_put_bignum(&msg, id->key->rsa->n);
 203                 } else {
 204                         u_char *blob;
 205                         u_int blen;
 206                         key_to_blob(id->key, &blob, &blen);
 207                         buffer_put_string(&msg, blob, blen);
 208                         xfree(blob);
 209                 }
 210                 buffer_put_cstring(&msg, id->comment);
 211         }
 212         buffer_put_int(&e->output, buffer_len(&msg));
 213         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 214         buffer_free(&msg);
 215 }
 216
 217 /* ssh1 only */
 218 static void
 219 process_authentication_challenge1(SocketEntry *e)
 220 {
 221         u_char buf[32], mdbuf[16], session_id[16];
 222         u_int response_type;
 223         BIGNUM *challenge;
 224         Identity *id;
 225         int i, len;
 226         Buffer msg;
 227         MD5_CTX md;
 228         Key *key;
 229
 230         buffer_init(&msg);
 231         key = key_new(KEY_RSA1);
 232         if ((challenge = BN_new()) == NULL)
 233                 fatal("process_authentication_challenge1: BN_new failed");
 234
 235         (void) buffer_get_int(&e->request);                     /* ignored */
 236         buffer_get_bignum(&e->request, key->rsa->e);
 237         buffer_get_bignum(&e->request, key->rsa->n);
 238         buffer_get_bignum(&e->request, challenge);
 239
 240         /* Only protocol 1.1 is supported */
 241         if (buffer_len(&e->request) == 0)
 242                 goto failure;
 243         buffer_get(&e->request, session_id, 16);
 244         response_type = buffer_get_int(&e->request);
 245         if (response_type != 1)
 246                 goto failure;
 247
 248         id = lookup_identity(key, 1);
 249         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 250                 Key *private = id->key;
 251                 /* Decrypt the challenge using the private key. */
 252                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 253                         goto failure;
 254
 255                 /* The response is MD5 of decrypted challenge plus session id. */
 256                 len = BN_num_bytes(challenge);
 257                 if (len <= 0 || len > 32) {
 258                         logit("process_authentication_challenge: bad challenge length %d", len);
 259                         goto failure;
 260                 }
 261                 memset(buf, 0, 32);
 262                 BN_bn2bin(challenge, buf + 32 - len);
 263                 MD5_Init(&md);
 264                 MD5_Update(&md, buf, 32);
 265                 MD5_Update(&md, session_id, 16);
 266                 MD5_Final(mdbuf, &md);
 267
 268                 /* Send the response. */
 269                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 270                 for (i = 0; i < 16; i++)
 271                         buffer_put_char(&msg, mdbuf[i]);
 272                 goto send;
 273         }
 274
 275 failure:
 276         /* Unknown identity or protocol error.  Send failure. */
 277         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 278 send:
 279         buffer_put_int(&e->output, buffer_len(&msg));
 280         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 281         key_free(key);
 282         BN_clear_free(challenge);
 283         buffer_free(&msg);
 284 }
 285
 286 /* ssh2 only */
 287 static void
 288 process_sign_request2(SocketEntry *e)
 289 {
 290         u_char *blob, *data, *signature = NULL;
 291         u_int blen, dlen, slen = 0;
 292         extern int datafellows;
 293         int ok = -1, flags;
 294         Buffer msg;
 295         Key *key;
 296
 297         datafellows = 0;
 298
 299         blob = buffer_get_string(&e->request, &blen);
 300         data = buffer_get_string(&e->request, &dlen);
 301
 302         flags = buffer_get_int(&e->request);
 303         if (flags & SSH_AGENT_OLD_SIGNATURE)
 304                 datafellows = SSH_BUG_SIGBLOB;
 305
 306         key = key_from_blob(blob, blen);
 307         if (key != NULL) {
 308                 Identity *id = lookup_identity(key, 2);
 309                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 310                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 311         }
 312         key_free(key);
 313         buffer_init(&msg);
 314         if (ok == 0) {
 315                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 316                 buffer_put_string(&msg, signature, slen);
 317         } else {
 318                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 319         }
 320         buffer_put_int(&e->output, buffer_len(&msg));
 321         buffer_append(&e->output, buffer_ptr(&msg),
 322             buffer_len(&msg));
 323         buffer_free(&msg);
 324         xfree(data);
 325         xfree(blob);
 326         if (signature != NULL)
 327                 xfree(signature);
 328 }
 329
 330 /* shared */
 331 static void
 332 process_remove_identity(SocketEntry *e, int version)
 333 {
 334         u_int blen, bits;
 335         int success = 0;
 336         Key *key = NULL;
 337         u_char *blob;
 338
 339         switch (version) {
 340         case 1:
 341                 key = key_new(KEY_RSA1);
 342                 bits = buffer_get_int(&e->request);
 343                 buffer_get_bignum(&e->request, key->rsa->e);
 344                 buffer_get_bignum(&e->request, key->rsa->n);
 345
 346                 if (bits != key_size(key))
 347                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 348                             key_size(key), bits);
 349                 break;
 350         case 2:
 351                 blob = buffer_get_string(&e->request, &blen);
 352                 key = key_from_blob(blob, blen);
 353                 xfree(blob);
 354                 break;
 355         }
 356         if (key != NULL) {
 357                 Identity *id = lookup_identity(key, version);
 358                 if (id != NULL) {
 359                         /*
 360                          * We have this key.  Free the old key.  Since we
 361                          * don't want to leave empty slots in the middle of
 362                          * the array, we actually free the key there and move
 363                          * all the entries between the empty slot and the end
 364                          * of the array.
 365                          */
 366                         Idtab *tab = idtab_lookup(version);
 367                         if (tab->nentries < 1)
 368                                 fatal("process_remove_identity: "
 369                                     "internal error: tab->nentries %d",
 370                                     tab->nentries);
 371                         TAILQ_REMOVE(&tab->idlist, id, next);
 372                         free_identity(id);
 373                         tab->nentries--;
 374                         success = 1;
 375                 }
 376                 key_free(key);
 377         }
 378         buffer_put_int(&e->output, 1);
 379         buffer_put_char(&e->output,
 380             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 381 }
 382
 383 static void
 384 process_remove_all_identities(SocketEntry *e, int version)
 385 {
 386         Idtab *tab = idtab_lookup(version);
 387         Identity *id;
 388
 389         /* Loop over all identities and clear the keys. */
 390         for (id = TAILQ_FIRST(&tab->idlist); id;
 391             id = TAILQ_FIRST(&tab->idlist)) {
 392                 TAILQ_REMOVE(&tab->idlist, id, next);
 393                 free_identity(id);
 394         }
 395
 396         /* Mark that there are no identities. */
 397         tab->nentries = 0;
 398
 399         /* Send success. */
 400         buffer_put_int(&e->output, 1);
 401         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 402 }
 403
 404 static void
 405 reaper(void)
 406 {
 407         u_int now = time(NULL);
 408         Identity *id, *nxt;
 409         int version;
 410         Idtab *tab;
 411
 412         for (version = 1; version < 3; version++) {
 413                 tab = idtab_lookup(version);
 414                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 415                         nxt = TAILQ_NEXT(id, next);
 416                         if (id->death != 0 && now >= id->death) {
 417                                 TAILQ_REMOVE(&tab->idlist, id, next);
 418                                 free_identity(id);
 419                                 tab->nentries--;
 420                         }
 421                 }
 422         }
 423 }
 424
 425 static void
 426 process_add_identity(SocketEntry *e, int version)
 427 {
 428         Idtab *tab = idtab_lookup(version);
 429         int type, success = 0, death = 0, confirm = 0;
 430         char *type_name, *comment;
 431         Key *k = NULL;
 432
 433         switch (version) {
 434         case 1:
 435                 k = key_new_private(KEY_RSA1);
 436                 (void) buffer_get_int(&e->request);             /* ignored */
 437                 buffer_get_bignum(&e->request, k->rsa->n);
 438                 buffer_get_bignum(&e->request, k->rsa->e);
 439                 buffer_get_bignum(&e->request, k->rsa->d);
 440                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 441
 442                 /* SSH and SSL have p and q swapped */
 443                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 444                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 445
 446                 /* Generate additional parameters */
 447                 rsa_generate_additional_parameters(k->rsa);
 448                 break;
 449         case 2:
 450                 type_name = buffer_get_string(&e->request, NULL);
 451                 type = key_type_from_name(type_name);
 452                 xfree(type_name);
 453                 switch (type) {
 454                 case KEY_DSA:
 455                         k = key_new_private(type);
 456                         buffer_get_bignum2(&e->request, k->dsa->p);
 457                         buffer_get_bignum2(&e->request, k->dsa->q);
 458                         buffer_get_bignum2(&e->request, k->dsa->g);
 459                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 460                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 461                         break;
 462                 case KEY_RSA:
 463                         k = key_new_private(type);
 464                         buffer_get_bignum2(&e->request, k->rsa->n);
 465                         buffer_get_bignum2(&e->request, k->rsa->e);
 466                         buffer_get_bignum2(&e->request, k->rsa->d);
 467                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 468                         buffer_get_bignum2(&e->request, k->rsa->p);
 469                         buffer_get_bignum2(&e->request, k->rsa->q);
 470
 471                         /* Generate additional parameters */
 472                         rsa_generate_additional_parameters(k->rsa);
 473                         break;
 474                 default:
 475                         buffer_clear(&e->request);
 476                         goto send;
 477                 }
 478                 break;
 479         }
 480         /* enable blinding */
 481         switch (k->type) {
 482         case KEY_RSA:
 483         case KEY_RSA1:
 484                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 485                         error("process_add_identity: RSA_blinding_on failed");
 486                         key_free(k);
 487                         goto send;
 488                 }
 489                 break;
 490         }
 491         comment = buffer_get_string(&e->request, NULL);
 492         if (k == NULL) {
 493                 xfree(comment);
 494                 goto send;
 495         }
 496         success = 1;
 497         while (buffer_len(&e->request)) {
 498                 switch (buffer_get_char(&e->request)) {
 499                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 500                         death = time(NULL) + buffer_get_int(&e->request);
 501                         break;
 502                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 503                         confirm = 1;
 504                         break;
 505                 default:
 506                         break;
 507                 }
 508         }
 509         if (lifetime && !death)
 510                 death = time(NULL) + lifetime;
 511         if (lookup_identity(k, version) == NULL) {
 512                 Identity *id = xmalloc(sizeof(Identity));
 513                 id->key = k;
 514                 id->comment = comment;
 515                 id->death = death;
 516                 id->confirm = confirm;
 517                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 518                 /* Increment the number of identities. */
 519                 tab->nentries++;
 520         } else {
 521                 key_free(k);
 522                 xfree(comment);
 523         }
 524 send:
 525         buffer_put_int(&e->output, 1);
 526         buffer_put_char(&e->output,
 527             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 528 }
 529
 530 /* XXX todo: encrypt sensitive data with passphrase */
 531 static void
 532 process_lock_agent(SocketEntry *e, int lock)
 533 {
 534         int success = 0;
 535         char *passwd;
 536
 537         passwd = buffer_get_string(&e->request, NULL);
 538         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 539                 locked = 0;
 540                 memset(lock_passwd, 0, strlen(lock_passwd));
 541                 xfree(lock_passwd);
 542                 lock_passwd = NULL;
 543                 success = 1;
 544         } else if (!locked && lock) {
 545                 locked = 1;
 546                 lock_passwd = xstrdup(passwd);
 547                 success = 1;
 548         }
 549         memset(passwd, 0, strlen(passwd));
 550         xfree(passwd);
 551
 552         buffer_put_int(&e->output, 1);
 553         buffer_put_char(&e->output,
 554             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 555 }
 556
 557 static void
 558 no_identities(SocketEntry *e, u_int type)
 559 {
 560         Buffer msg;
 561
 562         buffer_init(&msg);
 563         buffer_put_char(&msg,
 564             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 565             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 566         buffer_put_int(&msg, 0);
 567         buffer_put_int(&e->output, buffer_len(&msg));
 568         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 569         buffer_free(&msg);
 570 }
 571
 572 #ifdef SMARTCARD
 573 static void
 574 process_add_smartcard_key (SocketEntry *e)
 575 {
 576         char *sc_reader_id = NULL, *pin;
 577         int i, version, success = 0, death = 0, confirm = 0;
 578         Key **keys, *k;
 579         Identity *id;
 580         Idtab *tab;
 581
 582         sc_reader_id = buffer_get_string(&e->request, NULL);
 583         pin = buffer_get_string(&e->request, NULL);
 584
 585         while (buffer_len(&e->request)) {
 586                 switch (buffer_get_char(&e->request)) {
 587                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 588                         death = time(NULL) + buffer_get_int(&e->request);
 589                         break;
 590                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 591                         confirm = 1;
 592                         break;
 593                 default:
 594                         break;
 595                 }
 596         }
 597         if (lifetime && !death)
 598                 death = time(NULL) + lifetime;
 599
 600         keys = sc_get_keys(sc_reader_id, pin);
 601         xfree(sc_reader_id);
 602         xfree(pin);
 603
 604         if (keys == NULL || keys[0] == NULL) {
 605                 error("sc_get_keys failed");
 606                 goto send;
 607         }
 608         for (i = 0; keys[i] != NULL; i++) {
 609                 k = keys[i];
 610                 version = k->type == KEY_RSA1 ? 1 : 2;
 611                 tab = idtab_lookup(version);
 612                 if (lookup_identity(k, version) == NULL) {
 613                         id = xmalloc(sizeof(Identity));
 614                         id->key = k;
 615                         id->comment = sc_get_key_label(k);
 616                         id->death = death;
 617                         id->confirm = confirm;
 618                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 619                         tab->nentries++;
 620                         success = 1;
 621                 } else {
 622                         key_free(k);
 623                 }
 624                 keys[i] = NULL;
 625         }
 626         xfree(keys);
 627 send:
 628         buffer_put_int(&e->output, 1);
 629         buffer_put_char(&e->output,
 630             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 631 }
 632
 633 static void
 634 process_remove_smartcard_key(SocketEntry *e)
 635 {
 636         char *sc_reader_id = NULL, *pin;
 637         int i, version, success = 0;
 638         Key **keys, *k = NULL;
 639         Identity *id;
 640         Idtab *tab;
 641
 642         sc_reader_id = buffer_get_string(&e->request, NULL);
 643         pin = buffer_get_string(&e->request, NULL);
 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                 if ((id = lookup_identity(k, version)) != NULL) {
 656                         tab = idtab_lookup(version);
 657                         TAILQ_REMOVE(&tab->idlist, id, next);
 658                         tab->nentries--;
 659                         free_identity(id);
 660                         success = 1;
 661                 }
 662                 key_free(k);
 663                 keys[i] = NULL;
 664         }
 665         xfree(keys);
 666 send:
 667         buffer_put_int(&e->output, 1);
 668         buffer_put_char(&e->output,
 669             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 670 }
 671 #endif /* SMARTCARD */
 672
 673 /* dispatch incoming messages */
 674
 675 static void
 676 process_message(SocketEntry *e)
 677 {
 678         u_int msg_len, type;
 679         u_char *cp;
 680
 681         /* kill dead keys */
 682         reaper();
 683
 684         if (buffer_len(&e->input) < 5)
 685                 return;         /* Incomplete message. */
 686         cp = buffer_ptr(&e->input);
 687         msg_len = GET_32BIT(cp);
 688         if (msg_len > 256 * 1024) {
 689                 close_socket(e);
 690                 return;
 691         }
 692         if (buffer_len(&e->input) < msg_len + 4)
 693                 return;
 694
 695         /* move the current input to e->request */
 696         buffer_consume(&e->input, 4);
 697         buffer_clear(&e->request);
 698         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 699         buffer_consume(&e->input, msg_len);
 700         type = buffer_get_char(&e->request);
 701
 702         /* check wheter agent is locked */
 703         if (locked && type != SSH_AGENTC_UNLOCK) {
 704                 buffer_clear(&e->request);
 705                 switch (type) {
 706                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 707                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 708                         /* send empty lists */
 709                         no_identities(e, type);
 710                         break;
 711                 default:
 712                         /* send a fail message for all other request types */
 713                         buffer_put_int(&e->output, 1);
 714                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 715                 }
 716                 return;
 717         }
 718
 719         debug("type %d", type);
 720         switch (type) {
 721         case SSH_AGENTC_LOCK:
 722         case SSH_AGENTC_UNLOCK:
 723                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 724                 break;
 725         /* ssh1 */
 726         case SSH_AGENTC_RSA_CHALLENGE:
 727                 process_authentication_challenge1(e);
 728                 break;
 729         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 730                 process_request_identities(e, 1);
 731                 break;
 732         case SSH_AGENTC_ADD_RSA_IDENTITY:
 733         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 734                 process_add_identity(e, 1);
 735                 break;
 736         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 737                 process_remove_identity(e, 1);
 738                 break;
 739         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 740                 process_remove_all_identities(e, 1);
 741                 break;
 742         /* ssh2 */
 743         case SSH2_AGENTC_SIGN_REQUEST:
 744                 process_sign_request2(e);
 745                 break;
 746         case SSH2_AGENTC_REQUEST_IDENTITIES:
 747                 process_request_identities(e, 2);
 748                 break;
 749         case SSH2_AGENTC_ADD_IDENTITY:
 750         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 751                 process_add_identity(e, 2);
 752                 break;
 753         case SSH2_AGENTC_REMOVE_IDENTITY:
 754                 process_remove_identity(e, 2);
 755                 break;
 756         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 757                 process_remove_all_identities(e, 2);
 758                 break;
 759 #ifdef SMARTCARD
 760         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 761         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 762                 process_add_smartcard_key(e);
 763                 break;
 764         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 765                 process_remove_smartcard_key(e);
 766                 break;
 767 #endif /* SMARTCARD */
 768         default:
 769                 /* Unknown message.  Respond with failure. */
 770                 error("Unknown message %d", type);
 771                 buffer_clear(&e->request);
 772                 buffer_put_int(&e->output, 1);
 773                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 774                 break;
 775         }
 776 }
 777
 778 static void
 779 new_socket(sock_type type, int fd)
 780 {
 781         u_int i, old_alloc, new_alloc;
 782
 783         set_nonblock(fd);
 784
 785         if (fd > max_fd)
 786                 max_fd = fd;
 787
 788         for (i = 0; i < sockets_alloc; i++)
 789                 if (sockets[i].type == AUTH_UNUSED) {
 790                         sockets[i].fd = fd;
 791                         buffer_init(&sockets[i].input);
 792                         buffer_init(&sockets[i].output);
 793                         buffer_init(&sockets[i].request);
 794                         sockets[i].type = type;
 795                         return;
 796                 }
 797         old_alloc = sockets_alloc;
 798         new_alloc = sockets_alloc + 10;
 799         if (sockets)
 800                 sockets = xrealloc(sockets, new_alloc * sizeof(sockets[0]));
 801         else
 802                 sockets = xmalloc(new_alloc * sizeof(sockets[0]));
 803         for (i = old_alloc; i < new_alloc; i++)
 804                 sockets[i].type = AUTH_UNUSED;
 805         sockets_alloc = new_alloc;
 806         sockets[old_alloc].fd = fd;
 807         buffer_init(&sockets[old_alloc].input);
 808         buffer_init(&sockets[old_alloc].output);
 809         buffer_init(&sockets[old_alloc].request);
 810         sockets[old_alloc].type = type;
 811 }
 812
 813 static int
 814 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
 815 {
 816         u_int i, sz;
 817         int n = 0;
 818
 819         for (i = 0; i < sockets_alloc; i++) {
 820                 switch (sockets[i].type) {
 821                 case AUTH_SOCKET:
 822                 case AUTH_CONNECTION:
 823                         n = MAX(n, sockets[i].fd);
 824                         break;
 825                 case AUTH_UNUSED:
 826                         break;
 827                 default:
 828                         fatal("Unknown socket type %d", sockets[i].type);
 829                         break;
 830                 }
 831         }
 832
 833         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 834         if (*fdrp == NULL || sz > *nallocp) {
 835                 if (*fdrp)
 836                         xfree(*fdrp);
 837                 if (*fdwp)
 838                         xfree(*fdwp);
 839                 *fdrp = xmalloc(sz);
 840                 *fdwp = xmalloc(sz);
 841                 *nallocp = sz;
 842         }
 843         if (n < *fdl)
 844                 debug("XXX shrink: %d < %d", n, *fdl);
 845         *fdl = n;
 846         memset(*fdrp, 0, sz);
 847         memset(*fdwp, 0, sz);
 848
 849         for (i = 0; i < sockets_alloc; i++) {
 850                 switch (sockets[i].type) {
 851                 case AUTH_SOCKET:
 852                 case AUTH_CONNECTION:
 853                         FD_SET(sockets[i].fd, *fdrp);
 854                         if (buffer_len(&sockets[i].output) > 0)
 855                                 FD_SET(sockets[i].fd, *fdwp);
 856                         break;
 857                 default:
 858                         break;
 859                 }
 860         }
 861         return (1);
 862 }
 863
 864 static void
 865 after_select(fd_set *readset, fd_set *writeset)
 866 {
 867         struct sockaddr_un sunaddr;
 868         socklen_t slen;
 869         char buf[1024];
 870         int len, sock;
 871         u_int i;
 872         uid_t euid;
 873         gid_t egid;
 874
 875         for (i = 0; i < sockets_alloc; i++)
 876                 switch (sockets[i].type) {
 877                 case AUTH_UNUSED:
 878                         break;
 879                 case AUTH_SOCKET:
 880                         if (FD_ISSET(sockets[i].fd, readset)) {
 881                                 slen = sizeof(sunaddr);
 882                                 sock = accept(sockets[i].fd,
 883                                     (struct sockaddr *) &sunaddr, &slen);
 884                                 if (sock < 0) {
 885                                         error("accept from AUTH_SOCKET: %s",
 886                                             strerror(errno));
 887                                         break;
 888                                 }
 889                                 if (getpeereid(sock, &euid, &egid) < 0) {
 890                                         error("getpeereid %d failed: %s",
 891                                             sock, strerror(errno));
 892                                         close(sock);
 893                                         break;
 894                                 }
 895                                 if ((euid != 0) && (getuid() != euid)) {
 896                                         error("uid mismatch: "
 897                                             "peer euid %u != uid %u",
 898                                             (u_int) euid, (u_int) getuid());
 899                                         close(sock);
 900                                         break;
 901                                 }
 902                                 new_socket(AUTH_CONNECTION, sock);
 903                         }
 904                         break;
 905                 case AUTH_CONNECTION:
 906                         if (buffer_len(&sockets[i].output) > 0 &&
 907                             FD_ISSET(sockets[i].fd, writeset)) {
 908                                 do {
 909                                         len = write(sockets[i].fd,
 910                                             buffer_ptr(&sockets[i].output),
 911                                             buffer_len(&sockets[i].output));
 912                                         if (len == -1 && (errno == EAGAIN ||
 913                                             errno == EINTR))
 914                                                 continue;
 915                                         break;
 916                                 } while (1);
 917                                 if (len <= 0) {
 918                                         close_socket(&sockets[i]);
 919                                         break;
 920                                 }
 921                                 buffer_consume(&sockets[i].output, len);
 922                         }
 923                         if (FD_ISSET(sockets[i].fd, readset)) {
 924                                 do {
 925                                         len = read(sockets[i].fd, buf, sizeof(buf));
 926                                         if (len == -1 && (errno == EAGAIN ||
 927                                             errno == EINTR))
 928                                                 continue;
 929                                         break;
 930                                 } while (1);
 931                                 if (len <= 0) {
 932                                         close_socket(&sockets[i]);
 933                                         break;
 934                                 }
 935                                 buffer_append(&sockets[i].input, buf, len);
 936                                 process_message(&sockets[i]);
 937                         }
 938                         break;
 939                 default:
 940                         fatal("Unknown type %d", sockets[i].type);
 941                 }
 942 }
 943
 944 static void
 945 cleanup_socket(void)
 946 {
 947         if (socket_name[0])
 948                 unlink(socket_name);
 949         if (socket_dir[0])
 950                 rmdir(socket_dir);
 951 }
 952
 953 void
 954 cleanup_exit(int i)
 955 {
 956         cleanup_socket();
 957         _exit(i);
 958 }
 959
 960 static void
 961 cleanup_handler(int sig)
 962 {
 963         cleanup_socket();
 964         _exit(2);
 965 }
 966
 967 static void
 968 check_parent_exists(int sig)
 969 {
 970         int save_errno = errno;
 971
 972         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 973                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 974                 cleanup_handler(sig); /* safe */
 975         }
 976         mysignal(SIGALRM, check_parent_exists);
 977         alarm(10);
 978         errno = save_errno;
 979 }
 980
 981 static void
 982 usage(void)
 983 {
 984         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 985             __progname);
 986         fprintf(stderr, "Options:\n");
 987         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 988         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 989         fprintf(stderr, "  -k          Kill the current agent.\n");
 990         fprintf(stderr, "  -d          Debug mode.\n");
 991         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 992         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
 993         exit(1);
 994 }
 995
 996 int
 997 main(int ac, char **av)
 998 {
 999         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1000         int sock, fd,  ch;
1001         u_int nalloc;
1002         char *shell, *format, *pidstr, *agentsocket = NULL;
1003         fd_set *readsetp = NULL, *writesetp = NULL;
1004         struct sockaddr_un sunaddr;
1005 #ifdef HAVE_SETRLIMIT
1006         struct rlimit rlim;
1007 #endif
1008         int prev_mask;
1009         extern int optind;
1010         extern char *optarg;
1011         pid_t pid;
1012         char pidstrbuf[1 + 3 * sizeof pid];
1013
1014         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1015         sanitise_stdfd();
1016
1017         /* drop */
1018         setegid(getgid());
1019         setgid(getgid());
1020
1021 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1022         /* Disable ptrace on Linux without sgid bit */
1023         prctl(PR_SET_DUMPABLE, 0);
1024 #endif
1025
1026         SSLeay_add_all_algorithms();
1027
1028         __progname = ssh_get_progname(av[0]);
1029         init_rng();
1030         seed_rng();
1031
1032         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1033                 switch (ch) {
1034                 case 'c':
1035                         if (s_flag)
1036                                 usage();
1037                         c_flag++;
1038                         break;
1039                 case 'k':
1040                         k_flag++;
1041                         break;
1042                 case 's':
1043                         if (c_flag)
1044                                 usage();
1045                         s_flag++;
1046                         break;
1047                 case 'd':
1048                         if (d_flag)
1049                                 usage();
1050                         d_flag++;
1051                         break;
1052                 case 'a':
1053                         agentsocket = optarg;
1054                         break;
1055                 case 't':
1056                         if ((lifetime = convtime(optarg)) == -1) {
1057                                 fprintf(stderr, "Invalid lifetime\n");
1058                                 usage();
1059                         }
1060                         break;
1061                 default:
1062                         usage();
1063                 }
1064         }
1065         ac -= optind;
1066         av += optind;
1067
1068         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1069                 usage();
1070
1071         if (ac == 0 && !c_flag && !s_flag) {
1072                 shell = getenv("SHELL");
1073                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1074                         c_flag = 1;
1075         }
1076         if (k_flag) {
1077                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1078                 if (pidstr == NULL) {
1079                         fprintf(stderr, "%s not set, cannot kill agent\n",
1080                             SSH_AGENTPID_ENV_NAME);
1081                         exit(1);
1082                 }
1083                 pid = atoi(pidstr);
1084                 if (pid < 1) {
1085                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
1086                             SSH_AGENTPID_ENV_NAME, pidstr);
1087                         exit(1);
1088                 }
1089                 if (kill(pid, SIGTERM) == -1) {
1090                         perror("kill");
1091                         exit(1);
1092                 }
1093                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1094                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1095                 printf(format, SSH_AGENTPID_ENV_NAME);
1096                 printf("echo Agent pid %ld killed;\n", (long)pid);
1097                 exit(0);
1098         }
1099         parent_pid = getpid();
1100
1101         if (agentsocket == NULL) {
1102                 /* Create private directory for agent socket */
1103                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1104                 if (mkdtemp(socket_dir) == NULL) {
1105                         perror("mkdtemp: private socket dir");
1106                         exit(1);
1107                 }
1108                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1109                     (long)parent_pid);
1110         } else {
1111                 /* Try to use specified agent socket */
1112                 socket_dir[0] = '\0';
1113                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1114         }
1115
1116         /*
1117          * Create socket early so it will exist before command gets run from
1118          * the parent.
1119          */
1120         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1121         if (sock < 0) {
1122                 perror("socket");
1123                 *socket_name = '\0'; /* Don't unlink any existing file */
1124                 cleanup_exit(1);
1125         }
1126         memset(&sunaddr, 0, sizeof(sunaddr));
1127         sunaddr.sun_family = AF_UNIX;
1128         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1129         prev_mask = umask(0177);
1130         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1131                 perror("bind");
1132                 *socket_name = '\0'; /* Don't unlink any existing file */
1133                 umask(prev_mask);
1134                 cleanup_exit(1);
1135         }
1136         umask(prev_mask);
1137         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1138                 perror("listen");
1139                 cleanup_exit(1);
1140         }
1141
1142         /*
1143          * Fork, and have the parent execute the command, if any, or present
1144          * the socket data.  The child continues as the authentication agent.
1145          */
1146         if (d_flag) {
1147                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1148                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1149                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1150                     SSH_AUTHSOCKET_ENV_NAME);
1151                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1152                 goto skip;
1153         }
1154         pid = fork();
1155         if (pid == -1) {
1156                 perror("fork");
1157                 cleanup_exit(1);
1158         }
1159         if (pid != 0) {         /* Parent - execute the given command. */
1160                 close(sock);
1161                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1162                 if (ac == 0) {
1163                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1164                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1165                             SSH_AUTHSOCKET_ENV_NAME);
1166                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1167                             SSH_AGENTPID_ENV_NAME);
1168                         printf("echo Agent pid %ld;\n", (long)pid);
1169                         exit(0);
1170                 }
1171                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1172                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1173                         perror("setenv");
1174                         exit(1);
1175                 }
1176                 execvp(av[0], av);
1177                 perror(av[0]);
1178                 exit(1);
1179         }
1180         /* child */
1181         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1182
1183         if (setsid() == -1) {
1184                 error("setsid: %s", strerror(errno));
1185                 cleanup_exit(1);
1186         }
1187
1188         (void)chdir("/");
1189         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1190                 /* XXX might close listen socket */
1191                 (void)dup2(fd, STDIN_FILENO);
1192                 (void)dup2(fd, STDOUT_FILENO);
1193                 (void)dup2(fd, STDERR_FILENO);
1194                 if (fd > 2)
1195                         close(fd);
1196         }
1197
1198 #ifdef HAVE_SETRLIMIT
1199         /* deny core dumps, since memory contains unencrypted private keys */
1200         rlim.rlim_cur = rlim.rlim_max = 0;
1201         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1202                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1203                 cleanup_exit(1);
1204         }
1205 #endif
1206
1207 skip:
1208         new_socket(AUTH_SOCKET, sock);
1209         if (ac > 0) {
1210                 mysignal(SIGALRM, check_parent_exists);
1211                 alarm(10);
1212         }
1213         idtab_init();
1214         if (!d_flag)
1215                 signal(SIGINT, SIG_IGN);
1216         signal(SIGPIPE, SIG_IGN);
1217         signal(SIGHUP, cleanup_handler);
1218         signal(SIGTERM, cleanup_handler);
1219         nalloc = 0;
1220
1221         while (1) {
1222                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1223                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1224                         if (errno == EINTR)
1225                                 continue;
1226                         fatal("select: %s", strerror(errno));
1227                 }
1228                 after_select(readsetp, writesetp);
1229         }
1230         /* NOTREACHED */
1231 }