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 1.118 2004/05/08 00:21:31 djm 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 #ifdef HAVE___PROGNAME
 110 extern char *__progname;
 111 #else
 112 char *__progname;
 113 #endif
 114
 115 /* Default lifetime (0 == forever) */
 116 static int lifetime = 0;
 117
 118 static void
 119 close_socket(SocketEntry *e)
 120 {
 121         close(e->fd);
 122         e->fd = -1;
 123         e->type = AUTH_UNUSED;
 124         buffer_free(&e->input);
 125         buffer_free(&e->output);
 126         buffer_free(&e->request);
 127 }
 128
 129 static void
 130 idtab_init(void)
 131 {
 132         int i;
 133
 134         for (i = 0; i <=2; i++) {
 135                 TAILQ_INIT(&idtable[i].idlist);
 136                 idtable[i].nentries = 0;
 137         }
 138 }
 139
 140 /* return private key table for requested protocol version */
 141 static Idtab *
 142 idtab_lookup(int version)
 143 {
 144         if (version < 1 || version > 2)
 145                 fatal("internal error, bad protocol version %d", version);
 146         return &idtable[version];
 147 }
 148
 149 static void
 150 free_identity(Identity *id)
 151 {
 152         key_free(id->key);
 153         xfree(id->comment);
 154         xfree(id);
 155 }
 156
 157 /* return matching private key for given public key */
 158 static Identity *
 159 lookup_identity(Key *key, int version)
 160 {
 161         Identity *id;
 162
 163         Idtab *tab = idtab_lookup(version);
 164         TAILQ_FOREACH(id, &tab->idlist, next) {
 165                 if (key_equal(key, id->key))
 166                         return (id);
 167         }
 168         return (NULL);
 169 }
 170
 171 /* Check confirmation of keysign request */
 172 static int
 173 confirm_key(Identity *id)
 174 {
 175         char *p, prompt[1024];
 176         int ret = -1;
 177
 178         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 179         snprintf(prompt, sizeof(prompt), "Allow use of key %s?\n"
 180             "Key fingerprint %s.", id->comment, p);
 181         xfree(p);
 182         p = read_passphrase(prompt, RP_ALLOW_EOF);
 183         if (p != NULL) {
 184                 /*
 185                  * Accept empty responses and responses consisting
 186                  * of the word "yes" as affirmative.
 187                  */
 188                 if (*p == '\0' || *p == '\n' || strcasecmp(p, "yes") == 0)
 189                         ret = 0;
 190                 xfree(p);
 191         }
 192         return (ret);
 193 }
 194
 195 /* send list of supported public keys to 'client' */
 196 static void
 197 process_request_identities(SocketEntry *e, int version)
 198 {
 199         Idtab *tab = idtab_lookup(version);
 200         Identity *id;
 201         Buffer msg;
 202
 203         buffer_init(&msg);
 204         buffer_put_char(&msg, (version == 1) ?
 205             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 206         buffer_put_int(&msg, tab->nentries);
 207         TAILQ_FOREACH(id, &tab->idlist, next) {
 208                 if (id->key->type == KEY_RSA1) {
 209                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 210                         buffer_put_bignum(&msg, id->key->rsa->e);
 211                         buffer_put_bignum(&msg, id->key->rsa->n);
 212                 } else {
 213                         u_char *blob;
 214                         u_int blen;
 215                         key_to_blob(id->key, &blob, &blen);
 216                         buffer_put_string(&msg, blob, blen);
 217                         xfree(blob);
 218                 }
 219                 buffer_put_cstring(&msg, id->comment);
 220         }
 221         buffer_put_int(&e->output, buffer_len(&msg));
 222         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 223         buffer_free(&msg);
 224 }
 225
 226 /* ssh1 only */
 227 static void
 228 process_authentication_challenge1(SocketEntry *e)
 229 {
 230         u_char buf[32], mdbuf[16], session_id[16];
 231         u_int response_type;
 232         BIGNUM *challenge;
 233         Identity *id;
 234         int i, len;
 235         Buffer msg;
 236         MD5_CTX md;
 237         Key *key;
 238
 239         buffer_init(&msg);
 240         key = key_new(KEY_RSA1);
 241         if ((challenge = BN_new()) == NULL)
 242                 fatal("process_authentication_challenge1: BN_new failed");
 243
 244         (void) buffer_get_int(&e->request);                     /* ignored */
 245         buffer_get_bignum(&e->request, key->rsa->e);
 246         buffer_get_bignum(&e->request, key->rsa->n);
 247         buffer_get_bignum(&e->request, challenge);
 248
 249         /* Only protocol 1.1 is supported */
 250         if (buffer_len(&e->request) == 0)
 251                 goto failure;
 252         buffer_get(&e->request, session_id, 16);
 253         response_type = buffer_get_int(&e->request);
 254         if (response_type != 1)
 255                 goto failure;
 256
 257         id = lookup_identity(key, 1);
 258         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 259                 Key *private = id->key;
 260                 /* Decrypt the challenge using the private key. */
 261                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 262                         goto failure;
 263
 264                 /* The response is MD5 of decrypted challenge plus session id. */
 265                 len = BN_num_bytes(challenge);
 266                 if (len <= 0 || len > 32) {
 267                         logit("process_authentication_challenge: bad challenge length %d", len);
 268                         goto failure;
 269                 }
 270                 memset(buf, 0, 32);
 271                 BN_bn2bin(challenge, buf + 32 - len);
 272                 MD5_Init(&md);
 273                 MD5_Update(&md, buf, 32);
 274                 MD5_Update(&md, session_id, 16);
 275                 MD5_Final(mdbuf, &md);
 276
 277                 /* Send the response. */
 278                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 279                 for (i = 0; i < 16; i++)
 280                         buffer_put_char(&msg, mdbuf[i]);
 281                 goto send;
 282         }
 283
 284 failure:
 285         /* Unknown identity or protocol error.  Send failure. */
 286         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 287 send:
 288         buffer_put_int(&e->output, buffer_len(&msg));
 289         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 290         key_free(key);
 291         BN_clear_free(challenge);
 292         buffer_free(&msg);
 293 }
 294
 295 /* ssh2 only */
 296 static void
 297 process_sign_request2(SocketEntry *e)
 298 {
 299         u_char *blob, *data, *signature = NULL;
 300         u_int blen, dlen, slen = 0;
 301         extern int datafellows;
 302         int ok = -1, flags;
 303         Buffer msg;
 304         Key *key;
 305
 306         datafellows = 0;
 307
 308         blob = buffer_get_string(&e->request, &blen);
 309         data = buffer_get_string(&e->request, &dlen);
 310
 311         flags = buffer_get_int(&e->request);
 312         if (flags & SSH_AGENT_OLD_SIGNATURE)
 313                 datafellows = SSH_BUG_SIGBLOB;
 314
 315         key = key_from_blob(blob, blen);
 316         if (key != NULL) {
 317                 Identity *id = lookup_identity(key, 2);
 318                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 319                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 320         }
 321         key_free(key);
 322         buffer_init(&msg);
 323         if (ok == 0) {
 324                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 325                 buffer_put_string(&msg, signature, slen);
 326         } else {
 327                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 328         }
 329         buffer_put_int(&e->output, buffer_len(&msg));
 330         buffer_append(&e->output, buffer_ptr(&msg),
 331             buffer_len(&msg));
 332         buffer_free(&msg);
 333         xfree(data);
 334         xfree(blob);
 335         if (signature != NULL)
 336                 xfree(signature);
 337 }
 338
 339 /* shared */
 340 static void
 341 process_remove_identity(SocketEntry *e, int version)
 342 {
 343         u_int blen, bits;
 344         int success = 0;
 345         Key *key = NULL;
 346         u_char *blob;
 347
 348         switch (version) {
 349         case 1:
 350                 key = key_new(KEY_RSA1);
 351                 bits = buffer_get_int(&e->request);
 352                 buffer_get_bignum(&e->request, key->rsa->e);
 353                 buffer_get_bignum(&e->request, key->rsa->n);
 354
 355                 if (bits != key_size(key))
 356                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 357                             key_size(key), bits);
 358                 break;
 359         case 2:
 360                 blob = buffer_get_string(&e->request, &blen);
 361                 key = key_from_blob(blob, blen);
 362                 xfree(blob);
 363                 break;
 364         }
 365         if (key != NULL) {
 366                 Identity *id = lookup_identity(key, version);
 367                 if (id != NULL) {
 368                         /*
 369                          * We have this key.  Free the old key.  Since we
 370                          * don\'t want to leave empty slots in the middle of
 371                          * the array, we actually free the key there and move
 372                          * all the entries between the empty slot and the end
 373                          * of the array.
 374                          */
 375                         Idtab *tab = idtab_lookup(version);
 376                         if (tab->nentries < 1)
 377                                 fatal("process_remove_identity: "
 378                                     "internal error: tab->nentries %d",
 379                                     tab->nentries);
 380                         TAILQ_REMOVE(&tab->idlist, id, next);
 381                         free_identity(id);
 382                         tab->nentries--;
 383                         success = 1;
 384                 }
 385                 key_free(key);
 386         }
 387         buffer_put_int(&e->output, 1);
 388         buffer_put_char(&e->output,
 389             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 390 }
 391
 392 static void
 393 process_remove_all_identities(SocketEntry *e, int version)
 394 {
 395         Idtab *tab = idtab_lookup(version);
 396         Identity *id;
 397
 398         /* Loop over all identities and clear the keys. */
 399         for (id = TAILQ_FIRST(&tab->idlist); id;
 400             id = TAILQ_FIRST(&tab->idlist)) {
 401                 TAILQ_REMOVE(&tab->idlist, id, next);
 402                 free_identity(id);
 403         }
 404
 405         /* Mark that there are no identities. */
 406         tab->nentries = 0;
 407
 408         /* Send success. */
 409         buffer_put_int(&e->output, 1);
 410         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 411 }
 412
 413 static void
 414 reaper(void)
 415 {
 416         u_int now = time(NULL);
 417         Identity *id, *nxt;
 418         int version;
 419         Idtab *tab;
 420
 421         for (version = 1; version < 3; version++) {
 422                 tab = idtab_lookup(version);
 423                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 424                         nxt = TAILQ_NEXT(id, next);
 425                         if (id->death != 0 && now >= id->death) {
 426                                 TAILQ_REMOVE(&tab->idlist, id, next);
 427                                 free_identity(id);
 428                                 tab->nentries--;
 429                         }
 430                 }
 431         }
 432 }
 433
 434 static void
 435 process_add_identity(SocketEntry *e, int version)
 436 {
 437         Idtab *tab = idtab_lookup(version);
 438         int type, success = 0, death = 0, confirm = 0;
 439         char *type_name, *comment;
 440         Key *k = NULL;
 441
 442         switch (version) {
 443         case 1:
 444                 k = key_new_private(KEY_RSA1);
 445                 (void) buffer_get_int(&e->request);             /* ignored */
 446                 buffer_get_bignum(&e->request, k->rsa->n);
 447                 buffer_get_bignum(&e->request, k->rsa->e);
 448                 buffer_get_bignum(&e->request, k->rsa->d);
 449                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 450
 451                 /* SSH and SSL have p and q swapped */
 452                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 453                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 454
 455                 /* Generate additional parameters */
 456                 rsa_generate_additional_parameters(k->rsa);
 457                 break;
 458         case 2:
 459                 type_name = buffer_get_string(&e->request, NULL);
 460                 type = key_type_from_name(type_name);
 461                 xfree(type_name);
 462                 switch (type) {
 463                 case KEY_DSA:
 464                         k = key_new_private(type);
 465                         buffer_get_bignum2(&e->request, k->dsa->p);
 466                         buffer_get_bignum2(&e->request, k->dsa->q);
 467                         buffer_get_bignum2(&e->request, k->dsa->g);
 468                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 469                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 470                         break;
 471                 case KEY_RSA:
 472                         k = key_new_private(type);
 473                         buffer_get_bignum2(&e->request, k->rsa->n);
 474                         buffer_get_bignum2(&e->request, k->rsa->e);
 475                         buffer_get_bignum2(&e->request, k->rsa->d);
 476                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 477                         buffer_get_bignum2(&e->request, k->rsa->p);
 478                         buffer_get_bignum2(&e->request, k->rsa->q);
 479
 480                         /* Generate additional parameters */
 481                         rsa_generate_additional_parameters(k->rsa);
 482                         break;
 483                 default:
 484                         buffer_clear(&e->request);
 485                         goto send;
 486                 }
 487                 break;
 488         }
 489         /* enable blinding */
 490         switch (k->type) {
 491         case KEY_RSA:
 492         case KEY_RSA1:
 493                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 494                         error("process_add_identity: RSA_blinding_on failed");
 495                         key_free(k);
 496                         goto send;
 497                 }
 498                 break;
 499         }
 500         comment = buffer_get_string(&e->request, NULL);
 501         if (k == NULL) {
 502                 xfree(comment);
 503                 goto send;
 504         }
 505         success = 1;
 506         while (buffer_len(&e->request)) {
 507                 switch (buffer_get_char(&e->request)) {
 508                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 509                         death = time(NULL) + buffer_get_int(&e->request);
 510                         break;
 511                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 512                         confirm = 1;
 513                         break;
 514                 default:
 515                         break;
 516                 }
 517         }
 518         if (lifetime && !death)
 519                 death = time(NULL) + lifetime;
 520         if (lookup_identity(k, version) == NULL) {
 521                 Identity *id = xmalloc(sizeof(Identity));
 522                 id->key = k;
 523                 id->comment = comment;
 524                 id->death = death;
 525                 id->confirm = confirm;
 526                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 527                 /* Increment the number of identities. */
 528                 tab->nentries++;
 529         } else {
 530                 key_free(k);
 531                 xfree(comment);
 532         }
 533 send:
 534         buffer_put_int(&e->output, 1);
 535         buffer_put_char(&e->output,
 536             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 537 }
 538
 539 /* XXX todo: encrypt sensitive data with passphrase */
 540 static void
 541 process_lock_agent(SocketEntry *e, int lock)
 542 {
 543         int success = 0;
 544         char *passwd;
 545
 546         passwd = buffer_get_string(&e->request, NULL);
 547         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 548                 locked = 0;
 549                 memset(lock_passwd, 0, strlen(lock_passwd));
 550                 xfree(lock_passwd);
 551                 lock_passwd = NULL;
 552                 success = 1;
 553         } else if (!locked && lock) {
 554                 locked = 1;
 555                 lock_passwd = xstrdup(passwd);
 556                 success = 1;
 557         }
 558         memset(passwd, 0, strlen(passwd));
 559         xfree(passwd);
 560
 561         buffer_put_int(&e->output, 1);
 562         buffer_put_char(&e->output,
 563             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 564 }
 565
 566 static void
 567 no_identities(SocketEntry *e, u_int type)
 568 {
 569         Buffer msg;
 570
 571         buffer_init(&msg);
 572         buffer_put_char(&msg,
 573             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 574             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 575         buffer_put_int(&msg, 0);
 576         buffer_put_int(&e->output, buffer_len(&msg));
 577         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 578         buffer_free(&msg);
 579 }
 580
 581 #ifdef SMARTCARD
 582 static void
 583 process_add_smartcard_key (SocketEntry *e)
 584 {
 585         char *sc_reader_id = NULL, *pin;
 586         int i, version, success = 0, death = 0, confirm = 0;
 587         Key **keys, *k;
 588         Identity *id;
 589         Idtab *tab;
 590
 591         sc_reader_id = buffer_get_string(&e->request, NULL);
 592         pin = buffer_get_string(&e->request, NULL);
 593
 594         while (buffer_len(&e->request)) {
 595                 switch (buffer_get_char(&e->request)) {
 596                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 597                         death = time(NULL) + buffer_get_int(&e->request);
 598                         break;
 599                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 600                         confirm = 1;
 601                         break;
 602                 default:
 603                         break;
 604                 }
 605         }
 606         if (lifetime && !death)
 607                 death = time(NULL) + lifetime;
 608
 609         keys = sc_get_keys(sc_reader_id, pin);
 610         xfree(sc_reader_id);
 611         xfree(pin);
 612
 613         if (keys == NULL || keys[0] == NULL) {
 614                 error("sc_get_keys failed");
 615                 goto send;
 616         }
 617         for (i = 0; keys[i] != NULL; i++) {
 618                 k = keys[i];
 619                 version = k->type == KEY_RSA1 ? 1 : 2;
 620                 tab = idtab_lookup(version);
 621                 if (lookup_identity(k, version) == NULL) {
 622                         id = xmalloc(sizeof(Identity));
 623                         id->key = k;
 624                         id->comment = sc_get_key_label(k);
 625                         id->death = death;
 626                         id->confirm = confirm;
 627                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 628                         tab->nentries++;
 629                         success = 1;
 630                 } else {
 631                         key_free(k);
 632                 }
 633                 keys[i] = NULL;
 634         }
 635         xfree(keys);
 636 send:
 637         buffer_put_int(&e->output, 1);
 638         buffer_put_char(&e->output,
 639             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 640 }
 641
 642 static void
 643 process_remove_smartcard_key(SocketEntry *e)
 644 {
 645         char *sc_reader_id = NULL, *pin;
 646         int i, version, success = 0;
 647         Key **keys, *k = NULL;
 648         Identity *id;
 649         Idtab *tab;
 650
 651         sc_reader_id = buffer_get_string(&e->request, NULL);
 652         pin = buffer_get_string(&e->request, NULL);
 653         keys = sc_get_keys(sc_reader_id, pin);
 654         xfree(sc_reader_id);
 655         xfree(pin);
 656
 657         if (keys == NULL || keys[0] == NULL) {
 658                 error("sc_get_keys failed");
 659                 goto send;
 660         }
 661         for (i = 0; keys[i] != NULL; i++) {
 662                 k = keys[i];
 663                 version = k->type == KEY_RSA1 ? 1 : 2;
 664                 if ((id = lookup_identity(k, version)) != NULL) {
 665                         tab = idtab_lookup(version);
 666                         TAILQ_REMOVE(&tab->idlist, id, next);
 667                         tab->nentries--;
 668                         free_identity(id);
 669                         success = 1;
 670                 }
 671                 key_free(k);
 672                 keys[i] = NULL;
 673         }
 674         xfree(keys);
 675 send:
 676         buffer_put_int(&e->output, 1);
 677         buffer_put_char(&e->output,
 678             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 679 }
 680 #endif /* SMARTCARD */
 681
 682 /* dispatch incoming messages */
 683
 684 static void
 685 process_message(SocketEntry *e)
 686 {
 687         u_int msg_len, type;
 688         u_char *cp;
 689
 690         /* kill dead keys */
 691         reaper();
 692
 693         if (buffer_len(&e->input) < 5)
 694                 return;         /* Incomplete message. */
 695         cp = buffer_ptr(&e->input);
 696         msg_len = GET_32BIT(cp);
 697         if (msg_len > 256 * 1024) {
 698                 close_socket(e);
 699                 return;
 700         }
 701         if (buffer_len(&e->input) < msg_len + 4)
 702                 return;
 703
 704         /* move the current input to e->request */
 705         buffer_consume(&e->input, 4);
 706         buffer_clear(&e->request);
 707         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 708         buffer_consume(&e->input, msg_len);
 709         type = buffer_get_char(&e->request);
 710
 711         /* check wheter agent is locked */
 712         if (locked && type != SSH_AGENTC_UNLOCK) {
 713                 buffer_clear(&e->request);
 714                 switch (type) {
 715                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 716                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 717                         /* send empty lists */
 718                         no_identities(e, type);
 719                         break;
 720                 default:
 721                         /* send a fail message for all other request types */
 722                         buffer_put_int(&e->output, 1);
 723                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 724                 }
 725                 return;
 726         }
 727
 728         debug("type %d", type);
 729         switch (type) {
 730         case SSH_AGENTC_LOCK:
 731         case SSH_AGENTC_UNLOCK:
 732                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 733                 break;
 734         /* ssh1 */
 735         case SSH_AGENTC_RSA_CHALLENGE:
 736                 process_authentication_challenge1(e);
 737                 break;
 738         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 739                 process_request_identities(e, 1);
 740                 break;
 741         case SSH_AGENTC_ADD_RSA_IDENTITY:
 742         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 743                 process_add_identity(e, 1);
 744                 break;
 745         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 746                 process_remove_identity(e, 1);
 747                 break;
 748         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 749                 process_remove_all_identities(e, 1);
 750                 break;
 751         /* ssh2 */
 752         case SSH2_AGENTC_SIGN_REQUEST:
 753                 process_sign_request2(e);
 754                 break;
 755         case SSH2_AGENTC_REQUEST_IDENTITIES:
 756                 process_request_identities(e, 2);
 757                 break;
 758         case SSH2_AGENTC_ADD_IDENTITY:
 759         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 760                 process_add_identity(e, 2);
 761                 break;
 762         case SSH2_AGENTC_REMOVE_IDENTITY:
 763                 process_remove_identity(e, 2);
 764                 break;
 765         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 766                 process_remove_all_identities(e, 2);
 767                 break;
 768 #ifdef SMARTCARD
 769         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 770         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 771                 process_add_smartcard_key(e);
 772                 break;
 773         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 774                 process_remove_smartcard_key(e);
 775                 break;
 776 #endif /* SMARTCARD */
 777         default:
 778                 /* Unknown message.  Respond with failure. */
 779                 error("Unknown message %d", type);
 780                 buffer_clear(&e->request);
 781                 buffer_put_int(&e->output, 1);
 782                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 783                 break;
 784         }
 785 }
 786
 787 static void
 788 new_socket(sock_type type, int fd)
 789 {
 790         u_int i, old_alloc, new_alloc;
 791
 792         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 793                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 794
 795         if (fd > max_fd)
 796                 max_fd = fd;
 797
 798         for (i = 0; i < sockets_alloc; i++)
 799                 if (sockets[i].type == AUTH_UNUSED) {
 800                         sockets[i].fd = fd;
 801                         buffer_init(&sockets[i].input);
 802                         buffer_init(&sockets[i].output);
 803                         buffer_init(&sockets[i].request);
 804                         sockets[i].type = type;
 805                         return;
 806                 }
 807         old_alloc = sockets_alloc;
 808         new_alloc = sockets_alloc + 10;
 809         if (sockets)
 810                 sockets = xrealloc(sockets, new_alloc * sizeof(sockets[0]));
 811         else
 812                 sockets = xmalloc(new_alloc * sizeof(sockets[0]));
 813         for (i = old_alloc; i < new_alloc; i++)
 814                 sockets[i].type = AUTH_UNUSED;
 815         sockets_alloc = new_alloc;
 816         sockets[old_alloc].fd = fd;
 817         buffer_init(&sockets[old_alloc].input);
 818         buffer_init(&sockets[old_alloc].output);
 819         buffer_init(&sockets[old_alloc].request);
 820         sockets[old_alloc].type = type;
 821 }
 822
 823 static int
 824 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 825 {
 826         u_int i, sz;
 827         int n = 0;
 828
 829         for (i = 0; i < sockets_alloc; i++) {
 830                 switch (sockets[i].type) {
 831                 case AUTH_SOCKET:
 832                 case AUTH_CONNECTION:
 833                         n = MAX(n, sockets[i].fd);
 834                         break;
 835                 case AUTH_UNUSED:
 836                         break;
 837                 default:
 838                         fatal("Unknown socket type %d", sockets[i].type);
 839                         break;
 840                 }
 841         }
 842
 843         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 844         if (*fdrp == NULL || sz > *nallocp) {
 845                 if (*fdrp)
 846                         xfree(*fdrp);
 847                 if (*fdwp)
 848                         xfree(*fdwp);
 849                 *fdrp = xmalloc(sz);
 850                 *fdwp = xmalloc(sz);
 851                 *nallocp = sz;
 852         }
 853         if (n < *fdl)
 854                 debug("XXX shrink: %d < %d", n, *fdl);
 855         *fdl = n;
 856         memset(*fdrp, 0, sz);
 857         memset(*fdwp, 0, sz);
 858
 859         for (i = 0; i < sockets_alloc; i++) {
 860                 switch (sockets[i].type) {
 861                 case AUTH_SOCKET:
 862                 case AUTH_CONNECTION:
 863                         FD_SET(sockets[i].fd, *fdrp);
 864                         if (buffer_len(&sockets[i].output) > 0)
 865                                 FD_SET(sockets[i].fd, *fdwp);
 866                         break;
 867                 default:
 868                         break;
 869                 }
 870         }
 871         return (1);
 872 }
 873
 874 static void
 875 after_select(fd_set *readset, fd_set *writeset)
 876 {
 877         struct sockaddr_un sunaddr;
 878         socklen_t slen;
 879         char buf[1024];
 880         int len, sock;
 881         u_int i;
 882         uid_t euid;
 883         gid_t egid;
 884
 885         for (i = 0; i < sockets_alloc; i++)
 886                 switch (sockets[i].type) {
 887                 case AUTH_UNUSED:
 888                         break;
 889                 case AUTH_SOCKET:
 890                         if (FD_ISSET(sockets[i].fd, readset)) {
 891                                 slen = sizeof(sunaddr);
 892                                 sock = accept(sockets[i].fd,
 893                                     (struct sockaddr *) &sunaddr, &slen);
 894                                 if (sock < 0) {
 895                                         error("accept from AUTH_SOCKET: %s",
 896                                             strerror(errno));
 897                                         break;
 898                                 }
 899                                 if (getpeereid(sock, &euid, &egid) < 0) {
 900                                         error("getpeereid %d failed: %s",
 901                                             sock, strerror(errno));
 902                                         close(sock);
 903                                         break;
 904                                 }
 905                                 if ((euid != 0) && (getuid() != euid)) {
 906                                         error("uid mismatch: "
 907                                             "peer euid %u != uid %u",
 908                                             (u_int) euid, (u_int) getuid());
 909                                         close(sock);
 910                                         break;
 911                                 }
 912                                 new_socket(AUTH_CONNECTION, sock);
 913                         }
 914                         break;
 915                 case AUTH_CONNECTION:
 916                         if (buffer_len(&sockets[i].output) > 0 &&
 917                             FD_ISSET(sockets[i].fd, writeset)) {
 918                                 do {
 919                                         len = write(sockets[i].fd,
 920                                             buffer_ptr(&sockets[i].output),
 921                                             buffer_len(&sockets[i].output));
 922                                         if (len == -1 && (errno == EAGAIN ||
 923                                             errno == EINTR))
 924                                                 continue;
 925                                         break;
 926                                 } while (1);
 927                                 if (len <= 0) {
 928                                         close_socket(&sockets[i]);
 929                                         break;
 930                                 }
 931                                 buffer_consume(&sockets[i].output, len);
 932                         }
 933                         if (FD_ISSET(sockets[i].fd, readset)) {
 934                                 do {
 935                                         len = read(sockets[i].fd, buf, sizeof(buf));
 936                                         if (len == -1 && (errno == EAGAIN ||
 937                                             errno == EINTR))
 938                                                 continue;
 939                                         break;
 940                                 } while (1);
 941                                 if (len <= 0) {
 942                                         close_socket(&sockets[i]);
 943                                         break;
 944                                 }
 945                                 buffer_append(&sockets[i].input, buf, len);
 946                                 process_message(&sockets[i]);
 947                         }
 948                         break;
 949                 default:
 950                         fatal("Unknown type %d", sockets[i].type);
 951                 }
 952 }
 953
 954 static void
 955 cleanup_socket(void)
 956 {
 957         if (socket_name[0])
 958                 unlink(socket_name);
 959         if (socket_dir[0])
 960                 rmdir(socket_dir);
 961 }
 962
 963 void
 964 cleanup_exit(int i)
 965 {
 966         cleanup_socket();
 967         _exit(i);
 968 }
 969
 970 static void
 971 cleanup_handler(int sig)
 972 {
 973         cleanup_socket();
 974         _exit(2);
 975 }
 976
 977 static void
 978 check_parent_exists(int sig)
 979 {
 980         int save_errno = errno;
 981
 982         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 983                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 984                 cleanup_handler(sig); /* safe */
 985         }
 986         mysignal(SIGALRM, check_parent_exists);
 987         alarm(10);
 988         errno = save_errno;
 989 }
 990
 991 static void
 992 usage(void)
 993 {
 994         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 995             __progname);
 996         fprintf(stderr, "Options:\n");
 997         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 998         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 999         fprintf(stderr, "  -k          Kill the current agent.\n");
1000         fprintf(stderr, "  -d          Debug mode.\n");
1001         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1002         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1003         exit(1);
1004 }
1005
1006 int
1007 main(int ac, char **av)
1008 {
1009         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1010         int sock, fd,  ch, nalloc;
1011         char *shell, *format, *pidstr, *agentsocket = NULL;
1012         fd_set *readsetp = NULL, *writesetp = NULL;
1013         struct sockaddr_un sunaddr;
1014 #ifdef HAVE_SETRLIMIT
1015         struct rlimit rlim;
1016 #endif
1017 #ifdef HAVE_CYGWIN
1018         int prev_mask;
1019 #endif
1020         extern int optind;
1021         extern char *optarg;
1022         pid_t pid;
1023         char pidstrbuf[1 + 3 * sizeof pid];
1024
1025         /* drop */
1026         setegid(getgid());
1027         setgid(getgid());
1028
1029 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1030         /* Disable ptrace on Linux without sgid bit */
1031         prctl(PR_SET_DUMPABLE, 0);
1032 #endif
1033
1034         SSLeay_add_all_algorithms();
1035
1036         __progname = ssh_get_progname(av[0]);
1037         init_rng();
1038         seed_rng();
1039
1040         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1041                 switch (ch) {
1042                 case 'c':
1043                         if (s_flag)
1044                                 usage();
1045                         c_flag++;
1046                         break;
1047                 case 'k':
1048                         k_flag++;
1049                         break;
1050                 case 's':
1051                         if (c_flag)
1052                                 usage();
1053                         s_flag++;
1054                         break;
1055                 case 'd':
1056                         if (d_flag)
1057                                 usage();
1058                         d_flag++;
1059                         break;
1060                 case 'a':
1061                         agentsocket = optarg;
1062                         break;
1063                 case 't':
1064                         if ((lifetime = convtime(optarg)) == -1) {
1065                                 fprintf(stderr, "Invalid lifetime\n");
1066                                 usage();
1067                         }
1068                         break;
1069                 default:
1070                         usage();
1071                 }
1072         }
1073         ac -= optind;
1074         av += optind;
1075
1076         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1077                 usage();
1078
1079         if (ac == 0 && !c_flag && !s_flag) {
1080                 shell = getenv("SHELL");
1081                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1082                         c_flag = 1;
1083         }
1084         if (k_flag) {
1085                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1086                 if (pidstr == NULL) {
1087                         fprintf(stderr, "%s not set, cannot kill agent\n",
1088                             SSH_AGENTPID_ENV_NAME);
1089                         exit(1);
1090                 }
1091                 pid = atoi(pidstr);
1092                 if (pid < 1) {
1093                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
1094                             SSH_AGENTPID_ENV_NAME, pidstr);
1095                         exit(1);
1096                 }
1097                 if (kill(pid, SIGTERM) == -1) {
1098                         perror("kill");
1099                         exit(1);
1100                 }
1101                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1102                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1103                 printf(format, SSH_AGENTPID_ENV_NAME);
1104                 printf("echo Agent pid %ld killed;\n", (long)pid);
1105                 exit(0);
1106         }
1107         parent_pid = getpid();
1108
1109         if (agentsocket == NULL) {
1110                 /* Create private directory for agent socket */
1111                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1112                 if (mkdtemp(socket_dir) == NULL) {
1113                         perror("mkdtemp: private socket dir");
1114                         exit(1);
1115                 }
1116                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1117                     (long)parent_pid);
1118         } else {
1119                 /* Try to use specified agent socket */
1120                 socket_dir[0] = '\0';
1121                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1122         }
1123
1124         /*
1125          * Create socket early so it will exist before command gets run from
1126          * the parent.
1127          */
1128         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1129         if (sock < 0) {
1130                 perror("socket");
1131                 cleanup_exit(1);
1132         }
1133         memset(&sunaddr, 0, sizeof(sunaddr));
1134         sunaddr.sun_family = AF_UNIX;
1135         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1136 #ifdef HAVE_CYGWIN
1137         prev_mask = umask(0177);
1138 #endif
1139         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1140                 perror("bind");
1141 #ifdef HAVE_CYGWIN
1142                 umask(prev_mask);
1143 #endif
1144                 cleanup_exit(1);
1145         }
1146 #ifdef HAVE_CYGWIN
1147         umask(prev_mask);
1148 #endif
1149         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1150                 perror("listen");
1151                 cleanup_exit(1);
1152         }
1153
1154         /*
1155          * Fork, and have the parent execute the command, if any, or present
1156          * the socket data.  The child continues as the authentication agent.
1157          */
1158         if (d_flag) {
1159                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1160                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1161                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1162                     SSH_AUTHSOCKET_ENV_NAME);
1163                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1164                 goto skip;
1165         }
1166         pid = fork();
1167         if (pid == -1) {
1168                 perror("fork");
1169                 cleanup_exit(1);
1170         }
1171         if (pid != 0) {         /* Parent - execute the given command. */
1172                 close(sock);
1173                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1174                 if (ac == 0) {
1175                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1176                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1177                             SSH_AUTHSOCKET_ENV_NAME);
1178                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1179                             SSH_AGENTPID_ENV_NAME);
1180                         printf("echo Agent pid %ld;\n", (long)pid);
1181                         exit(0);
1182                 }
1183                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1184                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1185                         perror("setenv");
1186                         exit(1);
1187                 }
1188                 execvp(av[0], av);
1189                 perror(av[0]);
1190                 exit(1);
1191         }
1192         /* child */
1193         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1194
1195         if (setsid() == -1) {
1196                 error("setsid: %s", strerror(errno));
1197                 cleanup_exit(1);
1198         }
1199
1200         (void)chdir("/");
1201         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1202                 /* XXX might close listen socket */
1203                 (void)dup2(fd, STDIN_FILENO);
1204                 (void)dup2(fd, STDOUT_FILENO);
1205                 (void)dup2(fd, STDERR_FILENO);
1206                 if (fd > 2)
1207                         close(fd);
1208         }
1209
1210 #ifdef HAVE_SETRLIMIT
1211         /* deny core dumps, since memory contains unencrypted private keys */
1212         rlim.rlim_cur = rlim.rlim_max = 0;
1213         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1214                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1215                 cleanup_exit(1);
1216         }
1217 #endif
1218
1219 skip:
1220         new_socket(AUTH_SOCKET, sock);
1221         if (ac > 0) {
1222                 mysignal(SIGALRM, check_parent_exists);
1223                 alarm(10);
1224         }
1225         idtab_init();
1226         if (!d_flag)
1227                 signal(SIGINT, SIG_IGN);
1228         signal(SIGPIPE, SIG_IGN);
1229         signal(SIGHUP, cleanup_handler);
1230         signal(SIGTERM, cleanup_handler);
1231         nalloc = 0;
1232
1233         while (1) {
1234                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1235                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1236                         if (errno == EINTR)
1237                                 continue;
1238                         fatal("select: %s", strerror(errno));
1239                 }
1240                 after_select(readsetp, writesetp);
1241         }
1242         /* NOTREACHED */
1243 }