crypto/openssh-3.9p1/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 1.120 2004/08/11 21:43:05 avsm Exp $");
  39
  40 #include <openssl/evp.h>
  41 #include <openssl/md5.h>
  42
  43 #include "ssh.h"
  44 #include "rsa.h"
  45 #include "buffer.h"
  46 #include "bufaux.h"
  47 #include "xmalloc.h"
  48 #include "getput.h"
  49 #include "key.h"
  50 #include "authfd.h"
  51 #include "compat.h"
  52 #include "log.h"
  53 #include "misc.h"
  54
  55 #ifdef SMARTCARD
  56 #include "scard.h"
  57 #endif
  58
  59 #if defined(HAVE_SYS_PRCTL_H)
  60 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  61 #endif
  62
  63 typedef enum {
  64         AUTH_UNUSED,
  65         AUTH_SOCKET,
  66         AUTH_CONNECTION
  67 } sock_type;
  68
  69 typedef struct {
  70         int fd;
  71         sock_type type;
  72         Buffer input;
  73         Buffer output;
  74         Buffer request;
  75 } SocketEntry;
  76
  77 u_int sockets_alloc = 0;
  78 SocketEntry *sockets = NULL;
  79
  80 typedef struct identity {
  81         TAILQ_ENTRY(identity) next;
  82         Key *key;
  83         char *comment;
  84         u_int death;
  85         u_int confirm;
  86 } Identity;
  87
  88 typedef struct {
  89         int nentries;
  90         TAILQ_HEAD(idqueue, identity) idlist;
  91 } Idtab;
  92
  93 /* private key table, one per protocol version */
  94 Idtab idtable[3];
  95
  96 int max_fd = 0;
  97
  98 /* pid of shell == parent of agent */
  99 pid_t parent_pid = -1;
 100
 101 /* pathname and directory for AUTH_SOCKET */
 102 char socket_name[1024];
 103 char socket_dir[1024];
 104
 105 /* locking */
 106 int locked = 0;
 107 char *lock_passwd = NULL;
 108
 109 extern char *__progname;
 110
 111 /* Default lifetime (0 == forever) */
 112 static int lifetime = 0;
 113
 114 static void
 115 close_socket(SocketEntry *e)
 116 {
 117         close(e->fd);
 118         e->fd = -1;
 119         e->type = AUTH_UNUSED;
 120         buffer_free(&e->input);
 121         buffer_free(&e->output);
 122         buffer_free(&e->request);
 123 }
 124
 125 static void
 126 idtab_init(void)
 127 {
 128         int i;
 129
 130         for (i = 0; i <=2; i++) {
 131                 TAILQ_INIT(&idtable[i].idlist);
 132                 idtable[i].nentries = 0;
 133         }
 134 }
 135
 136 /* return private key table for requested protocol version */
 137 static Idtab *
 138 idtab_lookup(int version)
 139 {
 140         if (version < 1 || version > 2)
 141                 fatal("internal error, bad protocol version %d", version);
 142         return &idtable[version];
 143 }
 144
 145 static void
 146 free_identity(Identity *id)
 147 {
 148         key_free(id->key);
 149         xfree(id->comment);
 150         xfree(id);
 151 }
 152
 153 /* return matching private key for given public key */
 154 static Identity *
 155 lookup_identity(Key *key, int version)
 156 {
 157         Identity *id;
 158
 159         Idtab *tab = idtab_lookup(version);
 160         TAILQ_FOREACH(id, &tab->idlist, next) {
 161                 if (key_equal(key, id->key))
 162                         return (id);
 163         }
 164         return (NULL);
 165 }
 166
 167 /* Check confirmation of keysign request */
 168 static int
 169 confirm_key(Identity *id)
 170 {
 171         char *p, prompt[1024];
 172         int ret = -1;
 173
 174         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 175         snprintf(prompt, sizeof(prompt), "Allow use of key %s?\n"
 176             "Key fingerprint %s.", id->comment, p);
 177         xfree(p);
 178         p = read_passphrase(prompt, RP_ALLOW_EOF);
 179         if (p != NULL) {
 180                 /*
 181                  * Accept empty responses and responses consisting
 182                  * of the word "yes" as affirmative.
 183                  */
 184                 if (*p == '\0' || *p == '\n' || strcasecmp(p, "yes") == 0)
 185                         ret = 0;
 186                 xfree(p);
 187         }
 188         return (ret);
 189 }
 190
 191 /* send list of supported public keys to 'client' */
 192 static void
 193 process_request_identities(SocketEntry *e, int version)
 194 {
 195         Idtab *tab = idtab_lookup(version);
 196         Identity *id;
 197         Buffer msg;
 198
 199         buffer_init(&msg);
 200         buffer_put_char(&msg, (version == 1) ?
 201             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 202         buffer_put_int(&msg, tab->nentries);
 203         TAILQ_FOREACH(id, &tab->idlist, next) {
 204                 if (id->key->type == KEY_RSA1) {
 205                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 206                         buffer_put_bignum(&msg, id->key->rsa->e);
 207                         buffer_put_bignum(&msg, id->key->rsa->n);
 208                 } else {
 209                         u_char *blob;
 210                         u_int blen;
 211                         key_to_blob(id->key, &blob, &blen);
 212                         buffer_put_string(&msg, blob, blen);
 213                         xfree(blob);
 214                 }
 215                 buffer_put_cstring(&msg, id->comment);
 216         }
 217         buffer_put_int(&e->output, buffer_len(&msg));
 218         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 219         buffer_free(&msg);
 220 }
 221
 222 /* ssh1 only */
 223 static void
 224 process_authentication_challenge1(SocketEntry *e)
 225 {
 226         u_char buf[32], mdbuf[16], session_id[16];
 227         u_int response_type;
 228         BIGNUM *challenge;
 229         Identity *id;
 230         int i, len;
 231         Buffer msg;
 232         MD5_CTX md;
 233         Key *key;
 234
 235         buffer_init(&msg);
 236         key = key_new(KEY_RSA1);
 237         if ((challenge = BN_new()) == NULL)
 238                 fatal("process_authentication_challenge1: BN_new failed");
 239
 240         (void) buffer_get_int(&e->request);                     /* ignored */
 241         buffer_get_bignum(&e->request, key->rsa->e);
 242         buffer_get_bignum(&e->request, key->rsa->n);
 243         buffer_get_bignum(&e->request, challenge);
 244
 245         /* Only protocol 1.1 is supported */
 246         if (buffer_len(&e->request) == 0)
 247                 goto failure;
 248         buffer_get(&e->request, session_id, 16);
 249         response_type = buffer_get_int(&e->request);
 250         if (response_type != 1)
 251                 goto failure;
 252
 253         id = lookup_identity(key, 1);
 254         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 255                 Key *private = id->key;
 256                 /* Decrypt the challenge using the private key. */
 257                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 258                         goto failure;
 259
 260                 /* The response is MD5 of decrypted challenge plus session id. */
 261                 len = BN_num_bytes(challenge);
 262                 if (len <= 0 || len > 32) {
 263                         logit("process_authentication_challenge: bad challenge length %d", len);
 264                         goto failure;
 265                 }
 266                 memset(buf, 0, 32);
 267                 BN_bn2bin(challenge, buf + 32 - len);
 268                 MD5_Init(&md);
 269                 MD5_Update(&md, buf, 32);
 270                 MD5_Update(&md, session_id, 16);
 271                 MD5_Final(mdbuf, &md);
 272
 273                 /* Send the response. */
 274                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 275                 for (i = 0; i < 16; i++)
 276                         buffer_put_char(&msg, mdbuf[i]);
 277                 goto send;
 278         }
 279
 280 failure:
 281         /* Unknown identity or protocol error.  Send failure. */
 282         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 283 send:
 284         buffer_put_int(&e->output, buffer_len(&msg));
 285         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 286         key_free(key);
 287         BN_clear_free(challenge);
 288         buffer_free(&msg);
 289 }
 290
 291 /* ssh2 only */
 292 static void
 293 process_sign_request2(SocketEntry *e)
 294 {
 295         u_char *blob, *data, *signature = NULL;
 296         u_int blen, dlen, slen = 0;
 297         extern int datafellows;
 298         int ok = -1, flags;
 299         Buffer msg;
 300         Key *key;
 301
 302         datafellows = 0;
 303
 304         blob = buffer_get_string(&e->request, &blen);
 305         data = buffer_get_string(&e->request, &dlen);
 306
 307         flags = buffer_get_int(&e->request);
 308         if (flags & SSH_AGENT_OLD_SIGNATURE)
 309                 datafellows = SSH_BUG_SIGBLOB;
 310
 311         key = key_from_blob(blob, blen);
 312         if (key != NULL) {
 313                 Identity *id = lookup_identity(key, 2);
 314                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 315                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 316         }
 317         key_free(key);
 318         buffer_init(&msg);
 319         if (ok == 0) {
 320                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 321                 buffer_put_string(&msg, signature, slen);
 322         } else {
 323                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 324         }
 325         buffer_put_int(&e->output, buffer_len(&msg));
 326         buffer_append(&e->output, buffer_ptr(&msg),
 327             buffer_len(&msg));
 328         buffer_free(&msg);
 329         xfree(data);
 330         xfree(blob);
 331         if (signature != NULL)
 332                 xfree(signature);
 333 }
 334
 335 /* shared */
 336 static void
 337 process_remove_identity(SocketEntry *e, int version)
 338 {
 339         u_int blen, bits;
 340         int success = 0;
 341         Key *key = NULL;
 342         u_char *blob;
 343
 344         switch (version) {
 345         case 1:
 346                 key = key_new(KEY_RSA1);
 347                 bits = buffer_get_int(&e->request);
 348                 buffer_get_bignum(&e->request, key->rsa->e);
 349                 buffer_get_bignum(&e->request, key->rsa->n);
 350
 351                 if (bits != key_size(key))
 352                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 353                             key_size(key), bits);
 354                 break;
 355         case 2:
 356                 blob = buffer_get_string(&e->request, &blen);
 357                 key = key_from_blob(blob, blen);
 358                 xfree(blob);
 359                 break;
 360         }
 361         if (key != NULL) {
 362                 Identity *id = lookup_identity(key, version);
 363                 if (id != NULL) {
 364                         /*
 365                          * We have this key.  Free the old key.  Since we
 366                          * don\'t want to leave empty slots in the middle of
 367                          * the array, we actually free the key there and move
 368                          * all the entries between the empty slot and the end
 369                          * of the array.
 370                          */
 371                         Idtab *tab = idtab_lookup(version);
 372                         if (tab->nentries < 1)
 373                                 fatal("process_remove_identity: "
 374                                     "internal error: tab->nentries %d",
 375                                     tab->nentries);
 376                         TAILQ_REMOVE(&tab->idlist, id, next);
 377                         free_identity(id);
 378                         tab->nentries--;
 379                         success = 1;
 380                 }
 381                 key_free(key);
 382         }
 383         buffer_put_int(&e->output, 1);
 384         buffer_put_char(&e->output,
 385             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 386 }
 387
 388 static void
 389 process_remove_all_identities(SocketEntry *e, int version)
 390 {
 391         Idtab *tab = idtab_lookup(version);
 392         Identity *id;
 393
 394         /* Loop over all identities and clear the keys. */
 395         for (id = TAILQ_FIRST(&tab->idlist); id;
 396             id = TAILQ_FIRST(&tab->idlist)) {
 397                 TAILQ_REMOVE(&tab->idlist, id, next);
 398                 free_identity(id);
 399         }
 400
 401         /* Mark that there are no identities. */
 402         tab->nentries = 0;
 403
 404         /* Send success. */
 405         buffer_put_int(&e->output, 1);
 406         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 407 }
 408
 409 static void
 410 reaper(void)
 411 {
 412         u_int now = time(NULL);
 413         Identity *id, *nxt;
 414         int version;
 415         Idtab *tab;
 416
 417         for (version = 1; version < 3; version++) {
 418                 tab = idtab_lookup(version);
 419                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 420                         nxt = TAILQ_NEXT(id, next);
 421                         if (id->death != 0 && now >= id->death) {
 422                                 TAILQ_REMOVE(&tab->idlist, id, next);
 423                                 free_identity(id);
 424                                 tab->nentries--;
 425                         }
 426                 }
 427         }
 428 }
 429
 430 static void
 431 process_add_identity(SocketEntry *e, int version)
 432 {
 433         Idtab *tab = idtab_lookup(version);
 434         int type, success = 0, death = 0, confirm = 0;
 435         char *type_name, *comment;
 436         Key *k = NULL;
 437
 438         switch (version) {
 439         case 1:
 440                 k = key_new_private(KEY_RSA1);
 441                 (void) buffer_get_int(&e->request);             /* ignored */
 442                 buffer_get_bignum(&e->request, k->rsa->n);
 443                 buffer_get_bignum(&e->request, k->rsa->e);
 444                 buffer_get_bignum(&e->request, k->rsa->d);
 445                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 446
 447                 /* SSH and SSL have p and q swapped */
 448                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 449                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 450
 451                 /* Generate additional parameters */
 452                 rsa_generate_additional_parameters(k->rsa);
 453                 break;
 454         case 2:
 455                 type_name = buffer_get_string(&e->request, NULL);
 456                 type = key_type_from_name(type_name);
 457                 xfree(type_name);
 458                 switch (type) {
 459                 case KEY_DSA:
 460                         k = key_new_private(type);
 461                         buffer_get_bignum2(&e->request, k->dsa->p);
 462                         buffer_get_bignum2(&e->request, k->dsa->q);
 463                         buffer_get_bignum2(&e->request, k->dsa->g);
 464                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 465                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 466                         break;
 467                 case KEY_RSA:
 468                         k = key_new_private(type);
 469                         buffer_get_bignum2(&e->request, k->rsa->n);
 470                         buffer_get_bignum2(&e->request, k->rsa->e);
 471                         buffer_get_bignum2(&e->request, k->rsa->d);
 472                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 473                         buffer_get_bignum2(&e->request, k->rsa->p);
 474                         buffer_get_bignum2(&e->request, k->rsa->q);
 475
 476                         /* Generate additional parameters */
 477                         rsa_generate_additional_parameters(k->rsa);
 478                         break;
 479                 default:
 480                         buffer_clear(&e->request);
 481                         goto send;
 482                 }
 483                 break;
 484         }
 485         /* enable blinding */
 486         switch (k->type) {
 487         case KEY_RSA:
 488         case KEY_RSA1:
 489                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 490                         error("process_add_identity: RSA_blinding_on failed");
 491                         key_free(k);
 492                         goto send;
 493                 }
 494                 break;
 495         }
 496         comment = buffer_get_string(&e->request, NULL);
 497         if (k == NULL) {
 498                 xfree(comment);
 499                 goto send;
 500         }
 501         success = 1;
 502         while (buffer_len(&e->request)) {
 503                 switch (buffer_get_char(&e->request)) {
 504                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 505                         death = time(NULL) + buffer_get_int(&e->request);
 506                         break;
 507                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 508                         confirm = 1;
 509                         break;
 510                 default:
 511                         break;
 512                 }
 513         }
 514         if (lifetime && !death)
 515                 death = time(NULL) + lifetime;
 516         if (lookup_identity(k, version) == NULL) {
 517                 Identity *id = xmalloc(sizeof(Identity));
 518                 id->key = k;
 519                 id->comment = comment;
 520                 id->death = death;
 521                 id->confirm = confirm;
 522                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 523                 /* Increment the number of identities. */
 524                 tab->nentries++;
 525         } else {
 526                 key_free(k);
 527                 xfree(comment);
 528         }
 529 send:
 530         buffer_put_int(&e->output, 1);
 531         buffer_put_char(&e->output,
 532             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 533 }
 534
 535 /* XXX todo: encrypt sensitive data with passphrase */
 536 static void
 537 process_lock_agent(SocketEntry *e, int lock)
 538 {
 539         int success = 0;
 540         char *passwd;
 541
 542         passwd = buffer_get_string(&e->request, NULL);
 543         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 544                 locked = 0;
 545                 memset(lock_passwd, 0, strlen(lock_passwd));
 546                 xfree(lock_passwd);
 547                 lock_passwd = NULL;
 548                 success = 1;
 549         } else if (!locked && lock) {
 550                 locked = 1;
 551                 lock_passwd = xstrdup(passwd);
 552                 success = 1;
 553         }
 554         memset(passwd, 0, strlen(passwd));
 555         xfree(passwd);
 556
 557         buffer_put_int(&e->output, 1);
 558         buffer_put_char(&e->output,
 559             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 560 }
 561
 562 static void
 563 no_identities(SocketEntry *e, u_int type)
 564 {
 565         Buffer msg;
 566
 567         buffer_init(&msg);
 568         buffer_put_char(&msg,
 569             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 570             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 571         buffer_put_int(&msg, 0);
 572         buffer_put_int(&e->output, buffer_len(&msg));
 573         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 574         buffer_free(&msg);
 575 }
 576
 577 #ifdef SMARTCARD
 578 static void
 579 process_add_smartcard_key (SocketEntry *e)
 580 {
 581         char *sc_reader_id = NULL, *pin;
 582         int i, version, success = 0, death = 0, confirm = 0;
 583         Key **keys, *k;
 584         Identity *id;
 585         Idtab *tab;
 586
 587         sc_reader_id = buffer_get_string(&e->request, NULL);
 588         pin = buffer_get_string(&e->request, NULL);
 589
 590         while (buffer_len(&e->request)) {
 591                 switch (buffer_get_char(&e->request)) {
 592                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 593                         death = time(NULL) + buffer_get_int(&e->request);
 594                         break;
 595                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 596                         confirm = 1;
 597                         break;
 598                 default:
 599                         break;
 600                 }
 601         }
 602         if (lifetime && !death)
 603                 death = time(NULL) + lifetime;
 604
 605         keys = sc_get_keys(sc_reader_id, pin);
 606         xfree(sc_reader_id);
 607         xfree(pin);
 608
 609         if (keys == NULL || keys[0] == NULL) {
 610                 error("sc_get_keys failed");
 611                 goto send;
 612         }
 613         for (i = 0; keys[i] != NULL; i++) {
 614                 k = keys[i];
 615                 version = k->type == KEY_RSA1 ? 1 : 2;
 616                 tab = idtab_lookup(version);
 617                 if (lookup_identity(k, version) == NULL) {
 618                         id = xmalloc(sizeof(Identity));
 619                         id->key = k;
 620                         id->comment = sc_get_key_label(k);
 621                         id->death = death;
 622                         id->confirm = confirm;
 623                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 624                         tab->nentries++;
 625                         success = 1;
 626                 } else {
 627                         key_free(k);
 628                 }
 629                 keys[i] = NULL;
 630         }
 631         xfree(keys);
 632 send:
 633         buffer_put_int(&e->output, 1);
 634         buffer_put_char(&e->output,
 635             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 636 }
 637
 638 static void
 639 process_remove_smartcard_key(SocketEntry *e)
 640 {
 641         char *sc_reader_id = NULL, *pin;
 642         int i, version, success = 0;
 643         Key **keys, *k = NULL;
 644         Identity *id;
 645         Idtab *tab;
 646
 647         sc_reader_id = buffer_get_string(&e->request, NULL);
 648         pin = buffer_get_string(&e->request, NULL);
 649         keys = sc_get_keys(sc_reader_id, pin);
 650         xfree(sc_reader_id);
 651         xfree(pin);
 652
 653         if (keys == NULL || keys[0] == NULL) {
 654                 error("sc_get_keys failed");
 655                 goto send;
 656         }
 657         for (i = 0; keys[i] != NULL; i++) {
 658                 k = keys[i];
 659                 version = k->type == KEY_RSA1 ? 1 : 2;
 660                 if ((id = lookup_identity(k, version)) != NULL) {
 661                         tab = idtab_lookup(version);
 662                         TAILQ_REMOVE(&tab->idlist, id, next);
 663                         tab->nentries--;
 664                         free_identity(id);
 665                         success = 1;
 666                 }
 667                 key_free(k);
 668                 keys[i] = NULL;
 669         }
 670         xfree(keys);
 671 send:
 672         buffer_put_int(&e->output, 1);
 673         buffer_put_char(&e->output,
 674             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 675 }
 676 #endif /* SMARTCARD */
 677
 678 /* dispatch incoming messages */
 679
 680 static void
 681 process_message(SocketEntry *e)
 682 {
 683         u_int msg_len, type;
 684         u_char *cp;
 685
 686         /* kill dead keys */
 687         reaper();
 688
 689         if (buffer_len(&e->input) < 5)
 690                 return;         /* Incomplete message. */
 691         cp = buffer_ptr(&e->input);
 692         msg_len = GET_32BIT(cp);
 693         if (msg_len > 256 * 1024) {
 694                 close_socket(e);
 695                 return;
 696         }
 697         if (buffer_len(&e->input) < msg_len + 4)
 698                 return;
 699
 700         /* move the current input to e->request */
 701         buffer_consume(&e->input, 4);
 702         buffer_clear(&e->request);
 703         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 704         buffer_consume(&e->input, msg_len);
 705         type = buffer_get_char(&e->request);
 706
 707         /* check wheter agent is locked */
 708         if (locked && type != SSH_AGENTC_UNLOCK) {
 709                 buffer_clear(&e->request);
 710                 switch (type) {
 711                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 712                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 713                         /* send empty lists */
 714                         no_identities(e, type);
 715                         break;
 716                 default:
 717                         /* send a fail message for all other request types */
 718                         buffer_put_int(&e->output, 1);
 719                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 720                 }
 721                 return;
 722         }
 723
 724         debug("type %d", type);
 725         switch (type) {
 726         case SSH_AGENTC_LOCK:
 727         case SSH_AGENTC_UNLOCK:
 728                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 729                 break;
 730         /* ssh1 */
 731         case SSH_AGENTC_RSA_CHALLENGE:
 732                 process_authentication_challenge1(e);
 733                 break;
 734         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 735                 process_request_identities(e, 1);
 736                 break;
 737         case SSH_AGENTC_ADD_RSA_IDENTITY:
 738         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 739                 process_add_identity(e, 1);
 740                 break;
 741         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 742                 process_remove_identity(e, 1);
 743                 break;
 744         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 745                 process_remove_all_identities(e, 1);
 746                 break;
 747         /* ssh2 */
 748         case SSH2_AGENTC_SIGN_REQUEST:
 749                 process_sign_request2(e);
 750                 break;
 751         case SSH2_AGENTC_REQUEST_IDENTITIES:
 752                 process_request_identities(e, 2);
 753                 break;
 754         case SSH2_AGENTC_ADD_IDENTITY:
 755         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 756                 process_add_identity(e, 2);
 757                 break;
 758         case SSH2_AGENTC_REMOVE_IDENTITY:
 759                 process_remove_identity(e, 2);
 760                 break;
 761         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 762                 process_remove_all_identities(e, 2);
 763                 break;
 764 #ifdef SMARTCARD
 765         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 766         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 767                 process_add_smartcard_key(e);
 768                 break;
 769         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 770                 process_remove_smartcard_key(e);
 771                 break;
 772 #endif /* SMARTCARD */
 773         default:
 774                 /* Unknown message.  Respond with failure. */
 775                 error("Unknown message %d", type);
 776                 buffer_clear(&e->request);
 777                 buffer_put_int(&e->output, 1);
 778                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 779                 break;
 780         }
 781 }
 782
 783 static void
 784 new_socket(sock_type type, int fd)
 785 {
 786         u_int i, old_alloc, new_alloc;
 787
 788         set_nonblock(fd);
 789
 790         if (fd > max_fd)
 791                 max_fd = fd;
 792
 793         for (i = 0; i < sockets_alloc; i++)
 794                 if (sockets[i].type == AUTH_UNUSED) {
 795                         sockets[i].fd = fd;
 796                         buffer_init(&sockets[i].input);
 797                         buffer_init(&sockets[i].output);
 798                         buffer_init(&sockets[i].request);
 799                         sockets[i].type = type;
 800                         return;
 801                 }
 802         old_alloc = sockets_alloc;
 803         new_alloc = sockets_alloc + 10;
 804         if (sockets)
 805                 sockets = xrealloc(sockets, new_alloc * sizeof(sockets[0]));
 806         else
 807                 sockets = xmalloc(new_alloc * sizeof(sockets[0]));
 808         for (i = old_alloc; i < new_alloc; i++)
 809                 sockets[i].type = AUTH_UNUSED;
 810         sockets_alloc = new_alloc;
 811         sockets[old_alloc].fd = fd;
 812         buffer_init(&sockets[old_alloc].input);
 813         buffer_init(&sockets[old_alloc].output);
 814         buffer_init(&sockets[old_alloc].request);
 815         sockets[old_alloc].type = type;
 816 }
 817
 818 static int
 819 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
 820 {
 821         u_int i, sz;
 822         int n = 0;
 823
 824         for (i = 0; i < sockets_alloc; i++) {
 825                 switch (sockets[i].type) {
 826                 case AUTH_SOCKET:
 827                 case AUTH_CONNECTION:
 828                         n = MAX(n, sockets[i].fd);
 829                         break;
 830                 case AUTH_UNUSED:
 831                         break;
 832                 default:
 833                         fatal("Unknown socket type %d", sockets[i].type);
 834                         break;
 835                 }
 836         }
 837
 838         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 839         if (*fdrp == NULL || sz > *nallocp) {
 840                 if (*fdrp)
 841                         xfree(*fdrp);
 842                 if (*fdwp)
 843                         xfree(*fdwp);
 844                 *fdrp = xmalloc(sz);
 845                 *fdwp = xmalloc(sz);
 846                 *nallocp = sz;
 847         }
 848         if (n < *fdl)
 849                 debug("XXX shrink: %d < %d", n, *fdl);
 850         *fdl = n;
 851         memset(*fdrp, 0, sz);
 852         memset(*fdwp, 0, sz);
 853
 854         for (i = 0; i < sockets_alloc; i++) {
 855                 switch (sockets[i].type) {
 856                 case AUTH_SOCKET:
 857                 case AUTH_CONNECTION:
 858                         FD_SET(sockets[i].fd, *fdrp);
 859                         if (buffer_len(&sockets[i].output) > 0)
 860                                 FD_SET(sockets[i].fd, *fdwp);
 861                         break;
 862                 default:
 863                         break;
 864                 }
 865         }
 866         return (1);
 867 }
 868
 869 static void
 870 after_select(fd_set *readset, fd_set *writeset)
 871 {
 872         struct sockaddr_un sunaddr;
 873         socklen_t slen;
 874         char buf[1024];
 875         int len, sock;
 876         u_int i;
 877         uid_t euid;
 878         gid_t egid;
 879
 880         for (i = 0; i < sockets_alloc; i++)
 881                 switch (sockets[i].type) {
 882                 case AUTH_UNUSED:
 883                         break;
 884                 case AUTH_SOCKET:
 885                         if (FD_ISSET(sockets[i].fd, readset)) {
 886                                 slen = sizeof(sunaddr);
 887                                 sock = accept(sockets[i].fd,
 888                                     (struct sockaddr *) &sunaddr, &slen);
 889                                 if (sock < 0) {
 890                                         error("accept from AUTH_SOCKET: %s",
 891                                             strerror(errno));
 892                                         break;
 893                                 }
 894                                 if (getpeereid(sock, &euid, &egid) < 0) {
 895                                         error("getpeereid %d failed: %s",
 896                                             sock, strerror(errno));
 897                                         close(sock);
 898                                         break;
 899                                 }
 900                                 if ((euid != 0) && (getuid() != euid)) {
 901                                         error("uid mismatch: "
 902                                             "peer euid %u != uid %u",
 903                                             (u_int) euid, (u_int) getuid());
 904                                         close(sock);
 905                                         break;
 906                                 }
 907                                 new_socket(AUTH_CONNECTION, sock);
 908                         }
 909                         break;
 910                 case AUTH_CONNECTION:
 911                         if (buffer_len(&sockets[i].output) > 0 &&
 912                             FD_ISSET(sockets[i].fd, writeset)) {
 913                                 do {
 914                                         len = write(sockets[i].fd,
 915                                             buffer_ptr(&sockets[i].output),
 916                                             buffer_len(&sockets[i].output));
 917                                         if (len == -1 && (errno == EAGAIN ||
 918                                             errno == EINTR))
 919                                                 continue;
 920                                         break;
 921                                 } while (1);
 922                                 if (len <= 0) {
 923                                         close_socket(&sockets[i]);
 924                                         break;
 925                                 }
 926                                 buffer_consume(&sockets[i].output, len);
 927                         }
 928                         if (FD_ISSET(sockets[i].fd, readset)) {
 929                                 do {
 930                                         len = read(sockets[i].fd, buf, sizeof(buf));
 931                                         if (len == -1 && (errno == EAGAIN ||
 932                                             errno == EINTR))
 933                                                 continue;
 934                                         break;
 935                                 } while (1);
 936                                 if (len <= 0) {
 937                                         close_socket(&sockets[i]);
 938                                         break;
 939                                 }
 940                                 buffer_append(&sockets[i].input, buf, len);
 941                                 process_message(&sockets[i]);
 942                         }
 943                         break;
 944                 default:
 945                         fatal("Unknown type %d", sockets[i].type);
 946                 }
 947 }
 948
 949 static void
 950 cleanup_socket(void)
 951 {
 952         if (socket_name[0])
 953                 unlink(socket_name);
 954         if (socket_dir[0])
 955                 rmdir(socket_dir);
 956 }
 957
 958 void
 959 cleanup_exit(int i)
 960 {
 961         cleanup_socket();
 962         _exit(i);
 963 }
 964
 965 static void
 966 cleanup_handler(int sig)
 967 {
 968         cleanup_socket();
 969         _exit(2);
 970 }
 971
 972 static void
 973 check_parent_exists(int sig)
 974 {
 975         int save_errno = errno;
 976
 977         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 978                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 979                 cleanup_handler(sig); /* safe */
 980         }
 981         mysignal(SIGALRM, check_parent_exists);
 982         alarm(10);
 983         errno = save_errno;
 984 }
 985
 986 static void
 987 usage(void)
 988 {
 989         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 990             __progname);
 991         fprintf(stderr, "Options:\n");
 992         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 993         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 994         fprintf(stderr, "  -k          Kill the current agent.\n");
 995         fprintf(stderr, "  -d          Debug mode.\n");
 996         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 997         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
 998         exit(1);
 999 }
1000
1001 int
1002 main(int ac, char **av)
1003 {
1004         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1005         int sock, fd,  ch;
1006         u_int nalloc;
1007         char *shell, *format, *pidstr, *agentsocket = NULL;
1008         fd_set *readsetp = NULL, *writesetp = NULL;
1009         struct sockaddr_un sunaddr;
1010 #ifdef HAVE_SETRLIMIT
1011         struct rlimit rlim;
1012 #endif
1013 #ifdef HAVE_CYGWIN
1014         int prev_mask;
1015 #endif
1016         extern int optind;
1017         extern char *optarg;
1018         pid_t pid;
1019         char pidstrbuf[1 + 3 * sizeof pid];
1020
1021         /* drop */
1022         setegid(getgid());
1023         setgid(getgid());
1024
1025 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1026         /* Disable ptrace on Linux without sgid bit */
1027         prctl(PR_SET_DUMPABLE, 0);
1028 #endif
1029
1030         SSLeay_add_all_algorithms();
1031
1032         __progname = ssh_get_progname(av[0]);
1033         init_rng();
1034         seed_rng();
1035
1036         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1037                 switch (ch) {
1038                 case 'c':
1039                         if (s_flag)
1040                                 usage();
1041                         c_flag++;
1042                         break;
1043                 case 'k':
1044                         k_flag++;
1045                         break;
1046                 case 's':
1047                         if (c_flag)
1048                                 usage();
1049                         s_flag++;
1050                         break;
1051                 case 'd':
1052                         if (d_flag)
1053                                 usage();
1054                         d_flag++;
1055                         break;
1056                 case 'a':
1057                         agentsocket = optarg;
1058                         break;
1059                 case 't':
1060                         if ((lifetime = convtime(optarg)) == -1) {
1061                                 fprintf(stderr, "Invalid lifetime\n");
1062                                 usage();
1063                         }
1064                         break;
1065                 default:
1066                         usage();
1067                 }
1068         }
1069         ac -= optind;
1070         av += optind;
1071
1072         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1073                 usage();
1074
1075         if (ac == 0 && !c_flag && !s_flag) {
1076                 shell = getenv("SHELL");
1077                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1078                         c_flag = 1;
1079         }
1080         if (k_flag) {
1081                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1082                 if (pidstr == NULL) {
1083                         fprintf(stderr, "%s not set, cannot kill agent\n",
1084                             SSH_AGENTPID_ENV_NAME);
1085                         exit(1);
1086                 }
1087                 pid = atoi(pidstr);
1088                 if (pid < 1) {
1089                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
1090                             SSH_AGENTPID_ENV_NAME, pidstr);
1091                         exit(1);
1092                 }
1093                 if (kill(pid, SIGTERM) == -1) {
1094                         perror("kill");
1095                         exit(1);
1096                 }
1097                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1098                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1099                 printf(format, SSH_AGENTPID_ENV_NAME);
1100                 printf("echo Agent pid %ld killed;\n", (long)pid);
1101                 exit(0);
1102         }
1103         parent_pid = getpid();
1104
1105         if (agentsocket == NULL) {
1106                 /* Create private directory for agent socket */
1107                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1108                 if (mkdtemp(socket_dir) == NULL) {
1109                         perror("mkdtemp: private socket dir");
1110                         exit(1);
1111                 }
1112                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1113                     (long)parent_pid);
1114         } else {
1115                 /* Try to use specified agent socket */
1116                 socket_dir[0] = '\0';
1117                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1118         }
1119
1120         /*
1121          * Create socket early so it will exist before command gets run from
1122          * the parent.
1123          */
1124         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1125         if (sock < 0) {
1126                 perror("socket");
1127                 cleanup_exit(1);
1128         }
1129         memset(&sunaddr, 0, sizeof(sunaddr));
1130         sunaddr.sun_family = AF_UNIX;
1131         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1132 #ifdef HAVE_CYGWIN
1133         prev_mask = umask(0177);
1134 #endif
1135         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1136                 perror("bind");
1137 #ifdef HAVE_CYGWIN
1138                 umask(prev_mask);
1139 #endif
1140                 cleanup_exit(1);
1141         }
1142 #ifdef HAVE_CYGWIN
1143         umask(prev_mask);
1144 #endif
1145         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1146                 perror("listen");
1147                 cleanup_exit(1);
1148         }
1149
1150         /*
1151          * Fork, and have the parent execute the command, if any, or present
1152          * the socket data.  The child continues as the authentication agent.
1153          */
1154         if (d_flag) {
1155                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1156                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1157                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1158                     SSH_AUTHSOCKET_ENV_NAME);
1159                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1160                 goto skip;
1161         }
1162         pid = fork();
1163         if (pid == -1) {
1164                 perror("fork");
1165                 cleanup_exit(1);
1166         }
1167         if (pid != 0) {         /* Parent - execute the given command. */
1168                 close(sock);
1169                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1170                 if (ac == 0) {
1171                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1172                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1173                             SSH_AUTHSOCKET_ENV_NAME);
1174                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1175                             SSH_AGENTPID_ENV_NAME);
1176                         printf("echo Agent pid %ld;\n", (long)pid);
1177                         exit(0);
1178                 }
1179                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1180                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1181                         perror("setenv");
1182                         exit(1);
1183                 }
1184                 execvp(av[0], av);
1185                 perror(av[0]);
1186                 exit(1);
1187         }
1188         /* child */
1189         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1190
1191         if (setsid() == -1) {
1192                 error("setsid: %s", strerror(errno));
1193                 cleanup_exit(1);
1194         }
1195
1196         (void)chdir("/");
1197         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1198                 /* XXX might close listen socket */
1199                 (void)dup2(fd, STDIN_FILENO);
1200                 (void)dup2(fd, STDOUT_FILENO);
1201                 (void)dup2(fd, STDERR_FILENO);
1202                 if (fd > 2)
1203                         close(fd);
1204         }
1205
1206 #ifdef HAVE_SETRLIMIT
1207         /* deny core dumps, since memory contains unencrypted private keys */
1208         rlim.rlim_cur = rlim.rlim_max = 0;
1209         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1210                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1211                 cleanup_exit(1);
1212         }
1213 #endif
1214
1215 skip:
1216         new_socket(AUTH_SOCKET, sock);
1217         if (ac > 0) {
1218                 mysignal(SIGALRM, check_parent_exists);
1219                 alarm(10);
1220         }
1221         idtab_init();
1222         if (!d_flag)
1223                 signal(SIGINT, SIG_IGN);
1224         signal(SIGPIPE, SIG_IGN);
1225         signal(SIGHUP, cleanup_handler);
1226         signal(SIGTERM, cleanup_handler);
1227         nalloc = 0;
1228
1229         while (1) {
1230                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1231                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1232                         if (errno == EINTR)
1233                                 continue;
1234                         fatal("select: %s", strerror(errno));
1235                 }
1236                 after_select(readsetp, writesetp);
1237         }
1238         /* NOTREACHED */
1239 }