crypto/openssh-4/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 1.124 2005/10/30 08:52:18 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 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;
 172         int ret = -1;
 173
 174         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 175         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 176             id->comment, p))
 177                 ret = 0;
 178         xfree(p);
 179
 180         return (ret);
 181 }
 182
 183 /* send list of supported public keys to 'client' */
 184 static void
 185 process_request_identities(SocketEntry *e, int version)
 186 {
 187         Idtab *tab = idtab_lookup(version);
 188         Identity *id;
 189         Buffer msg;
 190
 191         buffer_init(&msg);
 192         buffer_put_char(&msg, (version == 1) ?
 193             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 194         buffer_put_int(&msg, tab->nentries);
 195         TAILQ_FOREACH(id, &tab->idlist, next) {
 196                 if (id->key->type == KEY_RSA1) {
 197                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 198                         buffer_put_bignum(&msg, id->key->rsa->e);
 199                         buffer_put_bignum(&msg, id->key->rsa->n);
 200                 } else {
 201                         u_char *blob;
 202                         u_int blen;
 203                         key_to_blob(id->key, &blob, &blen);
 204                         buffer_put_string(&msg, blob, blen);
 205                         xfree(blob);
 206                 }
 207                 buffer_put_cstring(&msg, id->comment);
 208         }
 209         buffer_put_int(&e->output, buffer_len(&msg));
 210         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 211         buffer_free(&msg);
 212 }
 213
 214 /* ssh1 only */
 215 static void
 216 process_authentication_challenge1(SocketEntry *e)
 217 {
 218         u_char buf[32], mdbuf[16], session_id[16];
 219         u_int response_type;
 220         BIGNUM *challenge;
 221         Identity *id;
 222         int i, len;
 223         Buffer msg;
 224         MD5_CTX md;
 225         Key *key;
 226
 227         buffer_init(&msg);
 228         key = key_new(KEY_RSA1);
 229         if ((challenge = BN_new()) == NULL)
 230                 fatal("process_authentication_challenge1: BN_new failed");
 231
 232         (void) buffer_get_int(&e->request);                     /* ignored */
 233         buffer_get_bignum(&e->request, key->rsa->e);
 234         buffer_get_bignum(&e->request, key->rsa->n);
 235         buffer_get_bignum(&e->request, challenge);
 236
 237         /* Only protocol 1.1 is supported */
 238         if (buffer_len(&e->request) == 0)
 239                 goto failure;
 240         buffer_get(&e->request, session_id, 16);
 241         response_type = buffer_get_int(&e->request);
 242         if (response_type != 1)
 243                 goto failure;
 244
 245         id = lookup_identity(key, 1);
 246         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 247                 Key *private = id->key;
 248                 /* Decrypt the challenge using the private key. */
 249                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 250                         goto failure;
 251
 252                 /* The response is MD5 of decrypted challenge plus session id. */
 253                 len = BN_num_bytes(challenge);
 254                 if (len <= 0 || len > 32) {
 255                         logit("process_authentication_challenge: bad challenge length %d", len);
 256                         goto failure;
 257                 }
 258                 memset(buf, 0, 32);
 259                 BN_bn2bin(challenge, buf + 32 - len);
 260                 MD5_Init(&md);
 261                 MD5_Update(&md, buf, 32);
 262                 MD5_Update(&md, session_id, 16);
 263                 MD5_Final(mdbuf, &md);
 264
 265                 /* Send the response. */
 266                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 267                 for (i = 0; i < 16; i++)
 268                         buffer_put_char(&msg, mdbuf[i]);
 269                 goto send;
 270         }
 271
 272 failure:
 273         /* Unknown identity or protocol error.  Send failure. */
 274         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 275 send:
 276         buffer_put_int(&e->output, buffer_len(&msg));
 277         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 278         key_free(key);
 279         BN_clear_free(challenge);
 280         buffer_free(&msg);
 281 }
 282
 283 /* ssh2 only */
 284 static void
 285 process_sign_request2(SocketEntry *e)
 286 {
 287         u_char *blob, *data, *signature = NULL;
 288         u_int blen, dlen, slen = 0;
 289         extern int datafellows;
 290         int ok = -1, flags;
 291         Buffer msg;
 292         Key *key;
 293
 294         datafellows = 0;
 295
 296         blob = buffer_get_string(&e->request, &blen);
 297         data = buffer_get_string(&e->request, &dlen);
 298
 299         flags = buffer_get_int(&e->request);
 300         if (flags & SSH_AGENT_OLD_SIGNATURE)
 301                 datafellows = SSH_BUG_SIGBLOB;
 302
 303         key = key_from_blob(blob, blen);
 304         if (key != NULL) {
 305                 Identity *id = lookup_identity(key, 2);
 306                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 307                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 308         }
 309         key_free(key);
 310         buffer_init(&msg);
 311         if (ok == 0) {
 312                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 313                 buffer_put_string(&msg, signature, slen);
 314         } else {
 315                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 316         }
 317         buffer_put_int(&e->output, buffer_len(&msg));
 318         buffer_append(&e->output, buffer_ptr(&msg),
 319             buffer_len(&msg));
 320         buffer_free(&msg);
 321         xfree(data);
 322         xfree(blob);
 323         if (signature != NULL)
 324                 xfree(signature);
 325 }
 326
 327 /* shared */
 328 static void
 329 process_remove_identity(SocketEntry *e, int version)
 330 {
 331         u_int blen, bits;
 332         int success = 0;
 333         Key *key = NULL;
 334         u_char *blob;
 335
 336         switch (version) {
 337         case 1:
 338                 key = key_new(KEY_RSA1);
 339                 bits = buffer_get_int(&e->request);
 340                 buffer_get_bignum(&e->request, key->rsa->e);
 341                 buffer_get_bignum(&e->request, key->rsa->n);
 342
 343                 if (bits != key_size(key))
 344                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 345                             key_size(key), bits);
 346                 break;
 347         case 2:
 348                 blob = buffer_get_string(&e->request, &blen);
 349                 key = key_from_blob(blob, blen);
 350                 xfree(blob);
 351                 break;
 352         }
 353         if (key != NULL) {
 354                 Identity *id = lookup_identity(key, version);
 355                 if (id != NULL) {
 356                         /*
 357                          * We have this key.  Free the old key.  Since we
 358                          * don't want to leave empty slots in the middle of
 359                          * the array, we actually free the key there and move
 360                          * all the entries between the empty slot and the end
 361                          * of the array.
 362                          */
 363                         Idtab *tab = idtab_lookup(version);
 364                         if (tab->nentries < 1)
 365                                 fatal("process_remove_identity: "
 366                                     "internal error: tab->nentries %d",
 367                                     tab->nentries);
 368                         TAILQ_REMOVE(&tab->idlist, id, next);
 369                         free_identity(id);
 370                         tab->nentries--;
 371                         success = 1;
 372                 }
 373                 key_free(key);
 374         }
 375         buffer_put_int(&e->output, 1);
 376         buffer_put_char(&e->output,
 377             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 378 }
 379
 380 static void
 381 process_remove_all_identities(SocketEntry *e, int version)
 382 {
 383         Idtab *tab = idtab_lookup(version);
 384         Identity *id;
 385
 386         /* Loop over all identities and clear the keys. */
 387         for (id = TAILQ_FIRST(&tab->idlist); id;
 388             id = TAILQ_FIRST(&tab->idlist)) {
 389                 TAILQ_REMOVE(&tab->idlist, id, next);
 390                 free_identity(id);
 391         }
 392
 393         /* Mark that there are no identities. */
 394         tab->nentries = 0;
 395
 396         /* Send success. */
 397         buffer_put_int(&e->output, 1);
 398         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 399 }
 400
 401 static void
 402 reaper(void)
 403 {
 404         u_int now = time(NULL);
 405         Identity *id, *nxt;
 406         int version;
 407         Idtab *tab;
 408
 409         for (version = 1; version < 3; version++) {
 410                 tab = idtab_lookup(version);
 411                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 412                         nxt = TAILQ_NEXT(id, next);
 413                         if (id->death != 0 && now >= id->death) {
 414                                 TAILQ_REMOVE(&tab->idlist, id, next);
 415                                 free_identity(id);
 416                                 tab->nentries--;
 417                         }
 418                 }
 419         }
 420 }
 421
 422 static void
 423 process_add_identity(SocketEntry *e, int version)
 424 {
 425         Idtab *tab = idtab_lookup(version);
 426         int type, success = 0, death = 0, confirm = 0;
 427         char *type_name, *comment;
 428         Key *k = NULL;
 429
 430         switch (version) {
 431         case 1:
 432                 k = key_new_private(KEY_RSA1);
 433                 (void) buffer_get_int(&e->request);             /* ignored */
 434                 buffer_get_bignum(&e->request, k->rsa->n);
 435                 buffer_get_bignum(&e->request, k->rsa->e);
 436                 buffer_get_bignum(&e->request, k->rsa->d);
 437                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 438
 439                 /* SSH and SSL have p and q swapped */
 440                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 441                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 442
 443                 /* Generate additional parameters */
 444                 rsa_generate_additional_parameters(k->rsa);
 445                 break;
 446         case 2:
 447                 type_name = buffer_get_string(&e->request, NULL);
 448                 type = key_type_from_name(type_name);
 449                 xfree(type_name);
 450                 switch (type) {
 451                 case KEY_DSA:
 452                         k = key_new_private(type);
 453                         buffer_get_bignum2(&e->request, k->dsa->p);
 454                         buffer_get_bignum2(&e->request, k->dsa->q);
 455                         buffer_get_bignum2(&e->request, k->dsa->g);
 456                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 457                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 458                         break;
 459                 case KEY_RSA:
 460                         k = key_new_private(type);
 461                         buffer_get_bignum2(&e->request, k->rsa->n);
 462                         buffer_get_bignum2(&e->request, k->rsa->e);
 463                         buffer_get_bignum2(&e->request, k->rsa->d);
 464                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 465                         buffer_get_bignum2(&e->request, k->rsa->p);
 466                         buffer_get_bignum2(&e->request, k->rsa->q);
 467
 468                         /* Generate additional parameters */
 469                         rsa_generate_additional_parameters(k->rsa);
 470                         break;
 471                 default:
 472                         buffer_clear(&e->request);
 473                         goto send;
 474                 }
 475                 break;
 476         }
 477         /* enable blinding */
 478         switch (k->type) {
 479         case KEY_RSA:
 480         case KEY_RSA1:
 481                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 482                         error("process_add_identity: RSA_blinding_on failed");
 483                         key_free(k);
 484                         goto send;
 485                 }
 486                 break;
 487         }
 488         comment = buffer_get_string(&e->request, NULL);
 489         if (k == NULL) {
 490                 xfree(comment);
 491                 goto send;
 492         }
 493         success = 1;
 494         while (buffer_len(&e->request)) {
 495                 switch (buffer_get_char(&e->request)) {
 496                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 497                         death = time(NULL) + buffer_get_int(&e->request);
 498                         break;
 499                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 500                         confirm = 1;
 501                         break;
 502                 default:
 503                         break;
 504                 }
 505         }
 506         if (lifetime && !death)
 507                 death = time(NULL) + lifetime;
 508         if (lookup_identity(k, version) == NULL) {
 509                 Identity *id = xmalloc(sizeof(Identity));
 510                 id->key = k;
 511                 id->comment = comment;
 512                 id->death = death;
 513                 id->confirm = confirm;
 514                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 515                 /* Increment the number of identities. */
 516                 tab->nentries++;
 517         } else {
 518                 key_free(k);
 519                 xfree(comment);
 520         }
 521 send:
 522         buffer_put_int(&e->output, 1);
 523         buffer_put_char(&e->output,
 524             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 525 }
 526
 527 /* XXX todo: encrypt sensitive data with passphrase */
 528 static void
 529 process_lock_agent(SocketEntry *e, int lock)
 530 {
 531         int success = 0;
 532         char *passwd;
 533
 534         passwd = buffer_get_string(&e->request, NULL);
 535         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 536                 locked = 0;
 537                 memset(lock_passwd, 0, strlen(lock_passwd));
 538                 xfree(lock_passwd);
 539                 lock_passwd = NULL;
 540                 success = 1;
 541         } else if (!locked && lock) {
 542                 locked = 1;
 543                 lock_passwd = xstrdup(passwd);
 544                 success = 1;
 545         }
 546         memset(passwd, 0, strlen(passwd));
 547         xfree(passwd);
 548
 549         buffer_put_int(&e->output, 1);
 550         buffer_put_char(&e->output,
 551             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 552 }
 553
 554 static void
 555 no_identities(SocketEntry *e, u_int type)
 556 {
 557         Buffer msg;
 558
 559         buffer_init(&msg);
 560         buffer_put_char(&msg,
 561             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 562             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 563         buffer_put_int(&msg, 0);
 564         buffer_put_int(&e->output, buffer_len(&msg));
 565         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 566         buffer_free(&msg);
 567 }
 568
 569 #ifdef SMARTCARD
 570 static void
 571 process_add_smartcard_key (SocketEntry *e)
 572 {
 573         char *sc_reader_id = NULL, *pin;
 574         int i, version, success = 0, death = 0, confirm = 0;
 575         Key **keys, *k;
 576         Identity *id;
 577         Idtab *tab;
 578
 579         sc_reader_id = buffer_get_string(&e->request, NULL);
 580         pin = buffer_get_string(&e->request, NULL);
 581
 582         while (buffer_len(&e->request)) {
 583                 switch (buffer_get_char(&e->request)) {
 584                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 585                         death = time(NULL) + buffer_get_int(&e->request);
 586                         break;
 587                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 588                         confirm = 1;
 589                         break;
 590                 default:
 591                         break;
 592                 }
 593         }
 594         if (lifetime && !death)
 595                 death = time(NULL) + lifetime;
 596
 597         keys = sc_get_keys(sc_reader_id, pin);
 598         xfree(sc_reader_id);
 599         xfree(pin);
 600
 601         if (keys == NULL || keys[0] == NULL) {
 602                 error("sc_get_keys failed");
 603                 goto send;
 604         }
 605         for (i = 0; keys[i] != NULL; i++) {
 606                 k = keys[i];
 607                 version = k->type == KEY_RSA1 ? 1 : 2;
 608                 tab = idtab_lookup(version);
 609                 if (lookup_identity(k, version) == NULL) {
 610                         id = xmalloc(sizeof(Identity));
 611                         id->key = k;
 612                         id->comment = sc_get_key_label(k);
 613                         id->death = death;
 614                         id->confirm = confirm;
 615                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 616                         tab->nentries++;
 617                         success = 1;
 618                 } else {
 619                         key_free(k);
 620                 }
 621                 keys[i] = NULL;
 622         }
 623         xfree(keys);
 624 send:
 625         buffer_put_int(&e->output, 1);
 626         buffer_put_char(&e->output,
 627             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 628 }
 629
 630 static void
 631 process_remove_smartcard_key(SocketEntry *e)
 632 {
 633         char *sc_reader_id = NULL, *pin;
 634         int i, version, success = 0;
 635         Key **keys, *k = NULL;
 636         Identity *id;
 637         Idtab *tab;
 638
 639         sc_reader_id = buffer_get_string(&e->request, NULL);
 640         pin = buffer_get_string(&e->request, NULL);
 641         keys = sc_get_keys(sc_reader_id, pin);
 642         xfree(sc_reader_id);
 643         xfree(pin);
 644
 645         if (keys == NULL || keys[0] == NULL) {
 646                 error("sc_get_keys failed");
 647                 goto send;
 648         }
 649         for (i = 0; keys[i] != NULL; i++) {
 650                 k = keys[i];
 651                 version = k->type == KEY_RSA1 ? 1 : 2;
 652                 if ((id = lookup_identity(k, version)) != NULL) {
 653                         tab = idtab_lookup(version);
 654                         TAILQ_REMOVE(&tab->idlist, id, next);
 655                         tab->nentries--;
 656                         free_identity(id);
 657                         success = 1;
 658                 }
 659                 key_free(k);
 660                 keys[i] = NULL;
 661         }
 662         xfree(keys);
 663 send:
 664         buffer_put_int(&e->output, 1);
 665         buffer_put_char(&e->output,
 666             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 667 }
 668 #endif /* SMARTCARD */
 669
 670 /* dispatch incoming messages */
 671
 672 static void
 673 process_message(SocketEntry *e)
 674 {
 675         u_int msg_len, type;
 676         u_char *cp;
 677
 678         /* kill dead keys */
 679         reaper();
 680
 681         if (buffer_len(&e->input) < 5)
 682                 return;         /* Incomplete message. */
 683         cp = buffer_ptr(&e->input);
 684         msg_len = GET_32BIT(cp);
 685         if (msg_len > 256 * 1024) {
 686                 close_socket(e);
 687                 return;
 688         }
 689         if (buffer_len(&e->input) < msg_len + 4)
 690                 return;
 691
 692         /* move the current input to e->request */
 693         buffer_consume(&e->input, 4);
 694         buffer_clear(&e->request);
 695         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 696         buffer_consume(&e->input, msg_len);
 697         type = buffer_get_char(&e->request);
 698
 699         /* check wheter agent is locked */
 700         if (locked && type != SSH_AGENTC_UNLOCK) {
 701                 buffer_clear(&e->request);
 702                 switch (type) {
 703                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 704                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 705                         /* send empty lists */
 706                         no_identities(e, type);
 707                         break;
 708                 default:
 709                         /* send a fail message for all other request types */
 710                         buffer_put_int(&e->output, 1);
 711                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 712                 }
 713                 return;
 714         }
 715
 716         debug("type %d", type);
 717         switch (type) {
 718         case SSH_AGENTC_LOCK:
 719         case SSH_AGENTC_UNLOCK:
 720                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 721                 break;
 722         /* ssh1 */
 723         case SSH_AGENTC_RSA_CHALLENGE:
 724                 process_authentication_challenge1(e);
 725                 break;
 726         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 727                 process_request_identities(e, 1);
 728                 break;
 729         case SSH_AGENTC_ADD_RSA_IDENTITY:
 730         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 731                 process_add_identity(e, 1);
 732                 break;
 733         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 734                 process_remove_identity(e, 1);
 735                 break;
 736         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 737                 process_remove_all_identities(e, 1);
 738                 break;
 739         /* ssh2 */
 740         case SSH2_AGENTC_SIGN_REQUEST:
 741                 process_sign_request2(e);
 742                 break;
 743         case SSH2_AGENTC_REQUEST_IDENTITIES:
 744                 process_request_identities(e, 2);
 745                 break;
 746         case SSH2_AGENTC_ADD_IDENTITY:
 747         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 748                 process_add_identity(e, 2);
 749                 break;
 750         case SSH2_AGENTC_REMOVE_IDENTITY:
 751                 process_remove_identity(e, 2);
 752                 break;
 753         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 754                 process_remove_all_identities(e, 2);
 755                 break;
 756 #ifdef SMARTCARD
 757         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 758         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 759                 process_add_smartcard_key(e);
 760                 break;
 761         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 762                 process_remove_smartcard_key(e);
 763                 break;
 764 #endif /* SMARTCARD */
 765         default:
 766                 /* Unknown message.  Respond with failure. */
 767                 error("Unknown message %d", type);
 768                 buffer_clear(&e->request);
 769                 buffer_put_int(&e->output, 1);
 770                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 771                 break;
 772         }
 773 }
 774
 775 static void
 776 new_socket(sock_type type, int fd)
 777 {
 778         u_int i, old_alloc, new_alloc;
 779
 780         set_nonblock(fd);
 781
 782         if (fd > max_fd)
 783                 max_fd = fd;
 784
 785         for (i = 0; i < sockets_alloc; i++)
 786                 if (sockets[i].type == AUTH_UNUSED) {
 787                         sockets[i].fd = fd;
 788                         buffer_init(&sockets[i].input);
 789                         buffer_init(&sockets[i].output);
 790                         buffer_init(&sockets[i].request);
 791                         sockets[i].type = type;
 792                         return;
 793                 }
 794         old_alloc = sockets_alloc;
 795         new_alloc = sockets_alloc + 10;
 796         if (sockets)
 797                 sockets = xrealloc(sockets, new_alloc * sizeof(sockets[0]));
 798         else
 799                 sockets = xmalloc(new_alloc * sizeof(sockets[0]));
 800         for (i = old_alloc; i < new_alloc; i++)
 801                 sockets[i].type = AUTH_UNUSED;
 802         sockets_alloc = new_alloc;
 803         sockets[old_alloc].fd = fd;
 804         buffer_init(&sockets[old_alloc].input);
 805         buffer_init(&sockets[old_alloc].output);
 806         buffer_init(&sockets[old_alloc].request);
 807         sockets[old_alloc].type = type;
 808 }
 809
 810 static int
 811 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
 812 {
 813         u_int i, sz;
 814         int n = 0;
 815
 816         for (i = 0; i < sockets_alloc; i++) {
 817                 switch (sockets[i].type) {
 818                 case AUTH_SOCKET:
 819                 case AUTH_CONNECTION:
 820                         n = MAX(n, sockets[i].fd);
 821                         break;
 822                 case AUTH_UNUSED:
 823                         break;
 824                 default:
 825                         fatal("Unknown socket type %d", sockets[i].type);
 826                         break;
 827                 }
 828         }
 829
 830         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 831         if (*fdrp == NULL || sz > *nallocp) {
 832                 if (*fdrp)
 833                         xfree(*fdrp);
 834                 if (*fdwp)
 835                         xfree(*fdwp);
 836                 *fdrp = xmalloc(sz);
 837                 *fdwp = xmalloc(sz);
 838                 *nallocp = sz;
 839         }
 840         if (n < *fdl)
 841                 debug("XXX shrink: %d < %d", n, *fdl);
 842         *fdl = n;
 843         memset(*fdrp, 0, sz);
 844         memset(*fdwp, 0, sz);
 845
 846         for (i = 0; i < sockets_alloc; i++) {
 847                 switch (sockets[i].type) {
 848                 case AUTH_SOCKET:
 849                 case AUTH_CONNECTION:
 850                         FD_SET(sockets[i].fd, *fdrp);
 851                         if (buffer_len(&sockets[i].output) > 0)
 852                                 FD_SET(sockets[i].fd, *fdwp);
 853                         break;
 854                 default:
 855                         break;
 856                 }
 857         }
 858         return (1);
 859 }
 860
 861 static void
 862 after_select(fd_set *readset, fd_set *writeset)
 863 {
 864         struct sockaddr_un sunaddr;
 865         socklen_t slen;
 866         char buf[1024];
 867         int len, sock;
 868         u_int i;
 869         uid_t euid;
 870         gid_t egid;
 871
 872         for (i = 0; i < sockets_alloc; i++)
 873                 switch (sockets[i].type) {
 874                 case AUTH_UNUSED:
 875                         break;
 876                 case AUTH_SOCKET:
 877                         if (FD_ISSET(sockets[i].fd, readset)) {
 878                                 slen = sizeof(sunaddr);
 879                                 sock = accept(sockets[i].fd,
 880                                     (struct sockaddr *) &sunaddr, &slen);
 881                                 if (sock < 0) {
 882                                         error("accept from AUTH_SOCKET: %s",
 883                                             strerror(errno));
 884                                         break;
 885                                 }
 886                                 if (getpeereid(sock, &euid, &egid) < 0) {
 887                                         error("getpeereid %d failed: %s",
 888                                             sock, strerror(errno));
 889                                         close(sock);
 890                                         break;
 891                                 }
 892                                 if ((euid != 0) && (getuid() != euid)) {
 893                                         error("uid mismatch: "
 894                                             "peer euid %u != uid %u",
 895                                             (u_int) euid, (u_int) getuid());
 896                                         close(sock);
 897                                         break;
 898                                 }
 899                                 new_socket(AUTH_CONNECTION, sock);
 900                         }
 901                         break;
 902                 case AUTH_CONNECTION:
 903                         if (buffer_len(&sockets[i].output) > 0 &&
 904                             FD_ISSET(sockets[i].fd, writeset)) {
 905                                 do {
 906                                         len = write(sockets[i].fd,
 907                                             buffer_ptr(&sockets[i].output),
 908                                             buffer_len(&sockets[i].output));
 909                                         if (len == -1 && (errno == EAGAIN ||
 910                                             errno == EINTR))
 911                                                 continue;
 912                                         break;
 913                                 } while (1);
 914                                 if (len <= 0) {
 915                                         close_socket(&sockets[i]);
 916                                         break;
 917                                 }
 918                                 buffer_consume(&sockets[i].output, len);
 919                         }
 920                         if (FD_ISSET(sockets[i].fd, readset)) {
 921                                 do {
 922                                         len = read(sockets[i].fd, buf, sizeof(buf));
 923                                         if (len == -1 && (errno == EAGAIN ||
 924                                             errno == EINTR))
 925                                                 continue;
 926                                         break;
 927                                 } while (1);
 928                                 if (len <= 0) {
 929                                         close_socket(&sockets[i]);
 930                                         break;
 931                                 }
 932                                 buffer_append(&sockets[i].input, buf, len);
 933                                 process_message(&sockets[i]);
 934                         }
 935                         break;
 936                 default:
 937                         fatal("Unknown type %d", sockets[i].type);
 938                 }
 939 }
 940
 941 static void
 942 cleanup_socket(void)
 943 {
 944         if (socket_name[0])
 945                 unlink(socket_name);
 946         if (socket_dir[0])
 947                 rmdir(socket_dir);
 948 }
 949
 950 void
 951 cleanup_exit(int i)
 952 {
 953         cleanup_socket();
 954         _exit(i);
 955 }
 956
 957 static void
 958 cleanup_handler(int sig)
 959 {
 960         cleanup_socket();
 961         _exit(2);
 962 }
 963
 964 static void
 965 check_parent_exists(int sig)
 966 {
 967         int save_errno = errno;
 968
 969         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 970                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 971                 cleanup_handler(sig); /* safe */
 972         }
 973         mysignal(SIGALRM, check_parent_exists);
 974         alarm(10);
 975         errno = save_errno;
 976 }
 977
 978 static void
 979 usage(void)
 980 {
 981         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 982             __progname);
 983         fprintf(stderr, "Options:\n");
 984         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 985         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 986         fprintf(stderr, "  -k          Kill the current agent.\n");
 987         fprintf(stderr, "  -d          Debug mode.\n");
 988         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 989         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
 990         exit(1);
 991 }
 992
 993 int
 994 main(int ac, char **av)
 995 {
 996         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
 997         int sock, fd,  ch;
 998         u_int nalloc;
 999         char *shell, *format, *pidstr, *agentsocket = NULL;
1000         fd_set *readsetp = NULL, *writesetp = NULL;
1001         struct sockaddr_un sunaddr;
1002 #ifdef HAVE_SETRLIMIT
1003         struct rlimit rlim;
1004 #endif
1005         int prev_mask;
1006         extern int optind;
1007         extern char *optarg;
1008         pid_t pid;
1009         char pidstrbuf[1 + 3 * sizeof pid];
1010
1011         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1012         sanitise_stdfd();
1013
1014         /* drop */
1015         setegid(getgid());
1016         setgid(getgid());
1017
1018 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1019         /* Disable ptrace on Linux without sgid bit */
1020         prctl(PR_SET_DUMPABLE, 0);
1021 #endif
1022
1023         SSLeay_add_all_algorithms();
1024
1025         __progname = ssh_get_progname(av[0]);
1026         init_rng();
1027         seed_rng();
1028
1029         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1030                 switch (ch) {
1031                 case 'c':
1032                         if (s_flag)
1033                                 usage();
1034                         c_flag++;
1035                         break;
1036                 case 'k':
1037                         k_flag++;
1038                         break;
1039                 case 's':
1040                         if (c_flag)
1041                                 usage();
1042                         s_flag++;
1043                         break;
1044                 case 'd':
1045                         if (d_flag)
1046                                 usage();
1047                         d_flag++;
1048                         break;
1049                 case 'a':
1050                         agentsocket = optarg;
1051                         break;
1052                 case 't':
1053                         if ((lifetime = convtime(optarg)) == -1) {
1054                                 fprintf(stderr, "Invalid lifetime\n");
1055                                 usage();
1056                         }
1057                         break;
1058                 default:
1059                         usage();
1060                 }
1061         }
1062         ac -= optind;
1063         av += optind;
1064
1065         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1066                 usage();
1067
1068         if (ac == 0 && !c_flag && !s_flag) {
1069                 shell = getenv("SHELL");
1070                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1071                         c_flag = 1;
1072         }
1073         if (k_flag) {
1074                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1075                 if (pidstr == NULL) {
1076                         fprintf(stderr, "%s not set, cannot kill agent\n",
1077                             SSH_AGENTPID_ENV_NAME);
1078                         exit(1);
1079                 }
1080                 pid = atoi(pidstr);
1081                 if (pid < 1) {
1082                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
1083                             SSH_AGENTPID_ENV_NAME, pidstr);
1084                         exit(1);
1085                 }
1086                 if (kill(pid, SIGTERM) == -1) {
1087                         perror("kill");
1088                         exit(1);
1089                 }
1090                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1091                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1092                 printf(format, SSH_AGENTPID_ENV_NAME);
1093                 printf("echo Agent pid %ld killed;\n", (long)pid);
1094                 exit(0);
1095         }
1096         parent_pid = getpid();
1097
1098         if (agentsocket == NULL) {
1099                 /* Create private directory for agent socket */
1100                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1101                 if (mkdtemp(socket_dir) == NULL) {
1102                         perror("mkdtemp: private socket dir");
1103                         exit(1);
1104                 }
1105                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1106                     (long)parent_pid);
1107         } else {
1108                 /* Try to use specified agent socket */
1109                 socket_dir[0] = '\0';
1110                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1111         }
1112
1113         /*
1114          * Create socket early so it will exist before command gets run from
1115          * the parent.
1116          */
1117         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1118         if (sock < 0) {
1119                 perror("socket");
1120                 *socket_name = '\0'; /* Don't unlink any existing file */
1121                 cleanup_exit(1);
1122         }
1123         memset(&sunaddr, 0, sizeof(sunaddr));
1124         sunaddr.sun_family = AF_UNIX;
1125         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1126         prev_mask = umask(0177);
1127         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1128                 perror("bind");
1129                 *socket_name = '\0'; /* Don't unlink any existing file */
1130                 umask(prev_mask);
1131                 cleanup_exit(1);
1132         }
1133         umask(prev_mask);
1134         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1135                 perror("listen");
1136                 cleanup_exit(1);
1137         }
1138
1139         /*
1140          * Fork, and have the parent execute the command, if any, or present
1141          * the socket data.  The child continues as the authentication agent.
1142          */
1143         if (d_flag) {
1144                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1145                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1146                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1147                     SSH_AUTHSOCKET_ENV_NAME);
1148                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1149                 goto skip;
1150         }
1151         pid = fork();
1152         if (pid == -1) {
1153                 perror("fork");
1154                 cleanup_exit(1);
1155         }
1156         if (pid != 0) {         /* Parent - execute the given command. */
1157                 close(sock);
1158                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1159                 if (ac == 0) {
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(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1164                             SSH_AGENTPID_ENV_NAME);
1165                         printf("echo Agent pid %ld;\n", (long)pid);
1166                         exit(0);
1167                 }
1168                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1169                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1170                         perror("setenv");
1171                         exit(1);
1172                 }
1173                 execvp(av[0], av);
1174                 perror(av[0]);
1175                 exit(1);
1176         }
1177         /* child */
1178         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1179
1180         if (setsid() == -1) {
1181                 error("setsid: %s", strerror(errno));
1182                 cleanup_exit(1);
1183         }
1184
1185         (void)chdir("/");
1186         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1187                 /* XXX might close listen socket */
1188                 (void)dup2(fd, STDIN_FILENO);
1189                 (void)dup2(fd, STDOUT_FILENO);
1190                 (void)dup2(fd, STDERR_FILENO);
1191                 if (fd > 2)
1192                         close(fd);
1193         }
1194
1195 #ifdef HAVE_SETRLIMIT
1196         /* deny core dumps, since memory contains unencrypted private keys */
1197         rlim.rlim_cur = rlim.rlim_max = 0;
1198         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1199                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1200                 cleanup_exit(1);
1201         }
1202 #endif
1203
1204 skip:
1205         new_socket(AUTH_SOCKET, sock);
1206         if (ac > 0) {
1207                 mysignal(SIGALRM, check_parent_exists);
1208                 alarm(10);
1209         }
1210         idtab_init();
1211         if (!d_flag)
1212                 signal(SIGINT, SIG_IGN);
1213         signal(SIGPIPE, SIG_IGN);
1214         signal(SIGHUP, cleanup_handler);
1215         signal(SIGTERM, cleanup_handler);
1216         nalloc = 0;
1217
1218         while (1) {
1219                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1220                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1221                         if (errno == EINTR)
1222                                 continue;
1223                         fatal("select: %s", strerror(errno));
1224                 }
1225                 after_select(readsetp, writesetp);
1226         }
1227         /* NOTREACHED */
1228 }