ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.148 2006/07/26 02:35:17 stevesk Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * The authentication agent program.
   7  *
   8  * As far as I am concerned, the code I have written for this software
   9  * can be used freely for any purpose.  Any derived versions of this
  10  * software must be clearly marked as such, and if the derived work is
  11  * incompatible with the protocol description in the RFC file, it must be
  12  * called by a name other than "ssh" or "Secure Shell".
  13  *
  14  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  15  *
  16  * Redistribution and use in source and binary forms, with or without
  17  * modification, are permitted provided that the following conditions
  18  * are met:
  19  * 1. Redistributions of source code must retain the above copyright
  20  *    notice, this list of conditions and the following disclaimer.
  21  * 2. Redistributions in binary form must reproduce the above copyright
  22  *    notice, this list of conditions and the following disclaimer in the
  23  *    documentation and/or other materials provided with the distribution.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  26  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  27  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  28  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  29  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  30  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  31  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  32  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  33  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  34  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  35  */
  36
  37 #include "includes.h"
  38
  39 #include <sys/types.h>
  40 #include <sys/param.h>
  41 #include <sys/resource.h>
  42 #include <sys/stat.h>
  43 #include <sys/socket.h>
  44 #ifdef HAVE_SYS_TIME_H
  45 # include <sys/time.h>
  46 #endif
  47 #ifdef HAVE_SYS_UN_H
  48 # include <sys/un.h>
  49 #endif
  50 #include "openbsd-compat/sys-queue.h"
  51
  52 #include <openssl/evp.h>
  53 #include <openssl/md5.h>
  54
  55 #include <errno.h>
  56 #include <fcntl.h>
  57 #ifdef HAVE_PATHS_H
  58 # include <paths.h>
  59 #endif
  60 #include <signal.h>
  61 #include <time.h>
  62 #include <string.h>
  63 #include <unistd.h>
  64
  65 #include "ssh.h"
  66 #include "rsa.h"
  67 #include "buffer.h"
  68 #include "bufaux.h"
  69 #include "xmalloc.h"
  70 #include "key.h"
  71 #include "authfd.h"
  72 #include "compat.h"
  73 #include "log.h"
  74 #include "misc.h"
  75
  76 #ifdef SMARTCARD
  77 #include "scard.h"
  78 #endif
  79
  80 #if defined(HAVE_SYS_PRCTL_H)
  81 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  82 #endif
  83
  84 typedef enum {
  85         AUTH_UNUSED,
  86         AUTH_SOCKET,
  87         AUTH_CONNECTION
  88 } sock_type;
  89
  90 typedef struct {
  91         int fd;
  92         sock_type type;
  93         Buffer input;
  94         Buffer output;
  95         Buffer request;
  96 } SocketEntry;
  97
  98 u_int sockets_alloc = 0;
  99 SocketEntry *sockets = NULL;
 100
 101 typedef struct identity {
 102         TAILQ_ENTRY(identity) next;
 103         Key *key;
 104         char *comment;
 105         u_int death;
 106         u_int confirm;
 107 } Identity;
 108
 109 typedef struct {
 110         int nentries;
 111         TAILQ_HEAD(idqueue, identity) idlist;
 112 } Idtab;
 113
 114 /* private key table, one per protocol version */
 115 Idtab idtable[3];
 116
 117 int max_fd = 0;
 118
 119 /* pid of shell == parent of agent */
 120 pid_t parent_pid = -1;
 121
 122 /* pathname and directory for AUTH_SOCKET */
 123 char socket_name[MAXPATHLEN];
 124 char socket_dir[MAXPATHLEN];
 125
 126 /* locking */
 127 int locked = 0;
 128 char *lock_passwd = NULL;
 129
 130 extern char *__progname;
 131
 132 /* Default lifetime (0 == forever) */
 133 static int lifetime = 0;
 134
 135 static void
 136 close_socket(SocketEntry *e)
 137 {
 138         close(e->fd);
 139         e->fd = -1;
 140         e->type = AUTH_UNUSED;
 141         buffer_free(&e->input);
 142         buffer_free(&e->output);
 143         buffer_free(&e->request);
 144 }
 145
 146 static void
 147 idtab_init(void)
 148 {
 149         int i;
 150
 151         for (i = 0; i <=2; i++) {
 152                 TAILQ_INIT(&idtable[i].idlist);
 153                 idtable[i].nentries = 0;
 154         }
 155 }
 156
 157 /* return private key table for requested protocol version */
 158 static Idtab *
 159 idtab_lookup(int version)
 160 {
 161         if (version < 1 || version > 2)
 162                 fatal("internal error, bad protocol version %d", version);
 163         return &idtable[version];
 164 }
 165
 166 static void
 167 free_identity(Identity *id)
 168 {
 169         key_free(id->key);
 170         xfree(id->comment);
 171         xfree(id);
 172 }
 173
 174 /* return matching private key for given public key */
 175 static Identity *
 176 lookup_identity(Key *key, int version)
 177 {
 178         Identity *id;
 179
 180         Idtab *tab = idtab_lookup(version);
 181         TAILQ_FOREACH(id, &tab->idlist, next) {
 182                 if (key_equal(key, id->key))
 183                         return (id);
 184         }
 185         return (NULL);
 186 }
 187
 188 /* Check confirmation of keysign request */
 189 static int
 190 confirm_key(Identity *id)
 191 {
 192         char *p;
 193         int ret = -1;
 194
 195         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 196         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 197             id->comment, p))
 198                 ret = 0;
 199         xfree(p);
 200
 201         return (ret);
 202 }
 203
 204 /* send list of supported public keys to 'client' */
 205 static void
 206 process_request_identities(SocketEntry *e, int version)
 207 {
 208         Idtab *tab = idtab_lookup(version);
 209         Identity *id;
 210         Buffer msg;
 211
 212         buffer_init(&msg);
 213         buffer_put_char(&msg, (version == 1) ?
 214             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 215         buffer_put_int(&msg, tab->nentries);
 216         TAILQ_FOREACH(id, &tab->idlist, next) {
 217                 if (id->key->type == KEY_RSA1) {
 218                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 219                         buffer_put_bignum(&msg, id->key->rsa->e);
 220                         buffer_put_bignum(&msg, id->key->rsa->n);
 221                 } else {
 222                         u_char *blob;
 223                         u_int blen;
 224                         key_to_blob(id->key, &blob, &blen);
 225                         buffer_put_string(&msg, blob, blen);
 226                         xfree(blob);
 227                 }
 228                 buffer_put_cstring(&msg, id->comment);
 229         }
 230         buffer_put_int(&e->output, buffer_len(&msg));
 231         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 232         buffer_free(&msg);
 233 }
 234
 235 /* ssh1 only */
 236 static void
 237 process_authentication_challenge1(SocketEntry *e)
 238 {
 239         u_char buf[32], mdbuf[16], session_id[16];
 240         u_int response_type;
 241         BIGNUM *challenge;
 242         Identity *id;
 243         int i, len;
 244         Buffer msg;
 245         MD5_CTX md;
 246         Key *key;
 247
 248         buffer_init(&msg);
 249         key = key_new(KEY_RSA1);
 250         if ((challenge = BN_new()) == NULL)
 251                 fatal("process_authentication_challenge1: BN_new failed");
 252
 253         (void) buffer_get_int(&e->request);                     /* ignored */
 254         buffer_get_bignum(&e->request, key->rsa->e);
 255         buffer_get_bignum(&e->request, key->rsa->n);
 256         buffer_get_bignum(&e->request, challenge);
 257
 258         /* Only protocol 1.1 is supported */
 259         if (buffer_len(&e->request) == 0)
 260                 goto failure;
 261         buffer_get(&e->request, session_id, 16);
 262         response_type = buffer_get_int(&e->request);
 263         if (response_type != 1)
 264                 goto failure;
 265
 266         id = lookup_identity(key, 1);
 267         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 268                 Key *private = id->key;
 269                 /* Decrypt the challenge using the private key. */
 270                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 271                         goto failure;
 272
 273                 /* The response is MD5 of decrypted challenge plus session id. */
 274                 len = BN_num_bytes(challenge);
 275                 if (len <= 0 || len > 32) {
 276                         logit("process_authentication_challenge: bad challenge length %d", len);
 277                         goto failure;
 278                 }
 279                 memset(buf, 0, 32);
 280                 BN_bn2bin(challenge, buf + 32 - len);
 281                 MD5_Init(&md);
 282                 MD5_Update(&md, buf, 32);
 283                 MD5_Update(&md, session_id, 16);
 284                 MD5_Final(mdbuf, &md);
 285
 286                 /* Send the response. */
 287                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 288                 for (i = 0; i < 16; i++)
 289                         buffer_put_char(&msg, mdbuf[i]);
 290                 goto send;
 291         }
 292
 293 failure:
 294         /* Unknown identity or protocol error.  Send failure. */
 295         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 296 send:
 297         buffer_put_int(&e->output, buffer_len(&msg));
 298         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 299         key_free(key);
 300         BN_clear_free(challenge);
 301         buffer_free(&msg);
 302 }
 303
 304 /* ssh2 only */
 305 static void
 306 process_sign_request2(SocketEntry *e)
 307 {
 308         u_char *blob, *data, *signature = NULL;
 309         u_int blen, dlen, slen = 0;
 310         extern int datafellows;
 311         int ok = -1, flags;
 312         Buffer msg;
 313         Key *key;
 314
 315         datafellows = 0;
 316
 317         blob = buffer_get_string(&e->request, &blen);
 318         data = buffer_get_string(&e->request, &dlen);
 319
 320         flags = buffer_get_int(&e->request);
 321         if (flags & SSH_AGENT_OLD_SIGNATURE)
 322                 datafellows = SSH_BUG_SIGBLOB;
 323
 324         key = key_from_blob(blob, blen);
 325         if (key != NULL) {
 326                 Identity *id = lookup_identity(key, 2);
 327                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 328                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 329                 key_free(key);
 330         }
 331         buffer_init(&msg);
 332         if (ok == 0) {
 333                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 334                 buffer_put_string(&msg, signature, slen);
 335         } else {
 336                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 337         }
 338         buffer_put_int(&e->output, buffer_len(&msg));
 339         buffer_append(&e->output, buffer_ptr(&msg),
 340             buffer_len(&msg));
 341         buffer_free(&msg);
 342         xfree(data);
 343         xfree(blob);
 344         if (signature != NULL)
 345                 xfree(signature);
 346 }
 347
 348 /* shared */
 349 static void
 350 process_remove_identity(SocketEntry *e, int version)
 351 {
 352         u_int blen, bits;
 353         int success = 0;
 354         Key *key = NULL;
 355         u_char *blob;
 356
 357         switch (version) {
 358         case 1:
 359                 key = key_new(KEY_RSA1);
 360                 bits = buffer_get_int(&e->request);
 361                 buffer_get_bignum(&e->request, key->rsa->e);
 362                 buffer_get_bignum(&e->request, key->rsa->n);
 363
 364                 if (bits != key_size(key))
 365                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 366                             key_size(key), bits);
 367                 break;
 368         case 2:
 369                 blob = buffer_get_string(&e->request, &blen);
 370                 key = key_from_blob(blob, blen);
 371                 xfree(blob);
 372                 break;
 373         }
 374         if (key != NULL) {
 375                 Identity *id = lookup_identity(key, version);
 376                 if (id != NULL) {
 377                         /*
 378                          * We have this key.  Free the old key.  Since we
 379                          * don't want to leave empty slots in the middle of
 380                          * the array, we actually free the key there and move
 381                          * all the entries between the empty slot and the end
 382                          * of the array.
 383                          */
 384                         Idtab *tab = idtab_lookup(version);
 385                         if (tab->nentries < 1)
 386                                 fatal("process_remove_identity: "
 387                                     "internal error: tab->nentries %d",
 388                                     tab->nentries);
 389                         TAILQ_REMOVE(&tab->idlist, id, next);
 390                         free_identity(id);
 391                         tab->nentries--;
 392                         success = 1;
 393                 }
 394                 key_free(key);
 395         }
 396         buffer_put_int(&e->output, 1);
 397         buffer_put_char(&e->output,
 398             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 399 }
 400
 401 static void
 402 process_remove_all_identities(SocketEntry *e, int version)
 403 {
 404         Idtab *tab = idtab_lookup(version);
 405         Identity *id;
 406
 407         /* Loop over all identities and clear the keys. */
 408         for (id = TAILQ_FIRST(&tab->idlist); id;
 409             id = TAILQ_FIRST(&tab->idlist)) {
 410                 TAILQ_REMOVE(&tab->idlist, id, next);
 411                 free_identity(id);
 412         }
 413
 414         /* Mark that there are no identities. */
 415         tab->nentries = 0;
 416
 417         /* Send success. */
 418         buffer_put_int(&e->output, 1);
 419         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 420 }
 421
 422 static void
 423 reaper(void)
 424 {
 425         u_int now = time(NULL);
 426         Identity *id, *nxt;
 427         int version;
 428         Idtab *tab;
 429
 430         for (version = 1; version < 3; version++) {
 431                 tab = idtab_lookup(version);
 432                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 433                         nxt = TAILQ_NEXT(id, next);
 434                         if (id->death != 0 && now >= id->death) {
 435                                 TAILQ_REMOVE(&tab->idlist, id, next);
 436                                 free_identity(id);
 437                                 tab->nentries--;
 438                         }
 439                 }
 440         }
 441 }
 442
 443 static void
 444 process_add_identity(SocketEntry *e, int version)
 445 {
 446         Idtab *tab = idtab_lookup(version);
 447         int type, success = 0, death = 0, confirm = 0;
 448         char *type_name, *comment;
 449         Key *k = NULL;
 450
 451         switch (version) {
 452         case 1:
 453                 k = key_new_private(KEY_RSA1);
 454                 (void) buffer_get_int(&e->request);             /* ignored */
 455                 buffer_get_bignum(&e->request, k->rsa->n);
 456                 buffer_get_bignum(&e->request, k->rsa->e);
 457                 buffer_get_bignum(&e->request, k->rsa->d);
 458                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 459
 460                 /* SSH and SSL have p and q swapped */
 461                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 462                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 463
 464                 /* Generate additional parameters */
 465                 rsa_generate_additional_parameters(k->rsa);
 466                 break;
 467         case 2:
 468                 type_name = buffer_get_string(&e->request, NULL);
 469                 type = key_type_from_name(type_name);
 470                 xfree(type_name);
 471                 switch (type) {
 472                 case KEY_DSA:
 473                         k = key_new_private(type);
 474                         buffer_get_bignum2(&e->request, k->dsa->p);
 475                         buffer_get_bignum2(&e->request, k->dsa->q);
 476                         buffer_get_bignum2(&e->request, k->dsa->g);
 477                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 478                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 479                         break;
 480                 case KEY_RSA:
 481                         k = key_new_private(type);
 482                         buffer_get_bignum2(&e->request, k->rsa->n);
 483                         buffer_get_bignum2(&e->request, k->rsa->e);
 484                         buffer_get_bignum2(&e->request, k->rsa->d);
 485                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 486                         buffer_get_bignum2(&e->request, k->rsa->p);
 487                         buffer_get_bignum2(&e->request, k->rsa->q);
 488
 489                         /* Generate additional parameters */
 490                         rsa_generate_additional_parameters(k->rsa);
 491                         break;
 492                 default:
 493                         buffer_clear(&e->request);
 494                         goto send;
 495                 }
 496                 break;
 497         }
 498         /* enable blinding */
 499         switch (k->type) {
 500         case KEY_RSA:
 501         case KEY_RSA1:
 502                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 503                         error("process_add_identity: RSA_blinding_on failed");
 504                         key_free(k);
 505                         goto send;
 506                 }
 507                 break;
 508         }
 509         comment = buffer_get_string(&e->request, NULL);
 510         if (k == NULL) {
 511                 xfree(comment);
 512                 goto send;
 513         }
 514         success = 1;
 515         while (buffer_len(&e->request)) {
 516                 switch (buffer_get_char(&e->request)) {
 517                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 518                         death = time(NULL) + buffer_get_int(&e->request);
 519                         break;
 520                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 521                         confirm = 1;
 522                         break;
 523                 default:
 524                         break;
 525                 }
 526         }
 527         if (lifetime && !death)
 528                 death = time(NULL) + lifetime;
 529         if (lookup_identity(k, version) == NULL) {
 530                 Identity *id = xmalloc(sizeof(Identity));
 531                 id->key = k;
 532                 id->comment = comment;
 533                 id->death = death;
 534                 id->confirm = confirm;
 535                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 536                 /* Increment the number of identities. */
 537                 tab->nentries++;
 538         } else {
 539                 key_free(k);
 540                 xfree(comment);
 541         }
 542 send:
 543         buffer_put_int(&e->output, 1);
 544         buffer_put_char(&e->output,
 545             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 546 }
 547
 548 /* XXX todo: encrypt sensitive data with passphrase */
 549 static void
 550 process_lock_agent(SocketEntry *e, int lock)
 551 {
 552         int success = 0;
 553         char *passwd;
 554
 555         passwd = buffer_get_string(&e->request, NULL);
 556         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 557                 locked = 0;
 558                 memset(lock_passwd, 0, strlen(lock_passwd));
 559                 xfree(lock_passwd);
 560                 lock_passwd = NULL;
 561                 success = 1;
 562         } else if (!locked && lock) {
 563                 locked = 1;
 564                 lock_passwd = xstrdup(passwd);
 565                 success = 1;
 566         }
 567         memset(passwd, 0, strlen(passwd));
 568         xfree(passwd);
 569
 570         buffer_put_int(&e->output, 1);
 571         buffer_put_char(&e->output,
 572             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 573 }
 574
 575 static void
 576 no_identities(SocketEntry *e, u_int type)
 577 {
 578         Buffer msg;
 579
 580         buffer_init(&msg);
 581         buffer_put_char(&msg,
 582             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 583             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 584         buffer_put_int(&msg, 0);
 585         buffer_put_int(&e->output, buffer_len(&msg));
 586         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 587         buffer_free(&msg);
 588 }
 589
 590 #ifdef SMARTCARD
 591 static void
 592 process_add_smartcard_key (SocketEntry *e)
 593 {
 594         char *sc_reader_id = NULL, *pin;
 595         int i, version, success = 0, death = 0, confirm = 0;
 596         Key **keys, *k;
 597         Identity *id;
 598         Idtab *tab;
 599
 600         sc_reader_id = buffer_get_string(&e->request, NULL);
 601         pin = buffer_get_string(&e->request, NULL);
 602
 603         while (buffer_len(&e->request)) {
 604                 switch (buffer_get_char(&e->request)) {
 605                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 606                         death = time(NULL) + buffer_get_int(&e->request);
 607                         break;
 608                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 609                         confirm = 1;
 610                         break;
 611                 default:
 612                         break;
 613                 }
 614         }
 615         if (lifetime && !death)
 616                 death = time(NULL) + lifetime;
 617
 618         keys = sc_get_keys(sc_reader_id, pin);
 619         xfree(sc_reader_id);
 620         xfree(pin);
 621
 622         if (keys == NULL || keys[0] == NULL) {
 623                 error("sc_get_keys failed");
 624                 goto send;
 625         }
 626         for (i = 0; keys[i] != NULL; i++) {
 627                 k = keys[i];
 628                 version = k->type == KEY_RSA1 ? 1 : 2;
 629                 tab = idtab_lookup(version);
 630                 if (lookup_identity(k, version) == NULL) {
 631                         id = xmalloc(sizeof(Identity));
 632                         id->key = k;
 633                         id->comment = sc_get_key_label(k);
 634                         id->death = death;
 635                         id->confirm = confirm;
 636                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 637                         tab->nentries++;
 638                         success = 1;
 639                 } else {
 640                         key_free(k);
 641                 }
 642                 keys[i] = NULL;
 643         }
 644         xfree(keys);
 645 send:
 646         buffer_put_int(&e->output, 1);
 647         buffer_put_char(&e->output,
 648             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 649 }
 650
 651 static void
 652 process_remove_smartcard_key(SocketEntry *e)
 653 {
 654         char *sc_reader_id = NULL, *pin;
 655         int i, version, success = 0;
 656         Key **keys, *k = NULL;
 657         Identity *id;
 658         Idtab *tab;
 659
 660         sc_reader_id = buffer_get_string(&e->request, NULL);
 661         pin = buffer_get_string(&e->request, NULL);
 662         keys = sc_get_keys(sc_reader_id, pin);
 663         xfree(sc_reader_id);
 664         xfree(pin);
 665
 666         if (keys == NULL || keys[0] == NULL) {
 667                 error("sc_get_keys failed");
 668                 goto send;
 669         }
 670         for (i = 0; keys[i] != NULL; i++) {
 671                 k = keys[i];
 672                 version = k->type == KEY_RSA1 ? 1 : 2;
 673                 if ((id = lookup_identity(k, version)) != NULL) {
 674                         tab = idtab_lookup(version);
 675                         TAILQ_REMOVE(&tab->idlist, id, next);
 676                         tab->nentries--;
 677                         free_identity(id);
 678                         success = 1;
 679                 }
 680                 key_free(k);
 681                 keys[i] = NULL;
 682         }
 683         xfree(keys);
 684 send:
 685         buffer_put_int(&e->output, 1);
 686         buffer_put_char(&e->output,
 687             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 688 }
 689 #endif /* SMARTCARD */
 690
 691 /* dispatch incoming messages */
 692
 693 static void
 694 process_message(SocketEntry *e)
 695 {
 696         u_int msg_len, type;
 697         u_char *cp;
 698
 699         /* kill dead keys */
 700         reaper();
 701
 702         if (buffer_len(&e->input) < 5)
 703                 return;         /* Incomplete message. */
 704         cp = buffer_ptr(&e->input);
 705         msg_len = get_u32(cp);
 706         if (msg_len > 256 * 1024) {
 707                 close_socket(e);
 708                 return;
 709         }
 710         if (buffer_len(&e->input) < msg_len + 4)
 711                 return;
 712
 713         /* move the current input to e->request */
 714         buffer_consume(&e->input, 4);
 715         buffer_clear(&e->request);
 716         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 717         buffer_consume(&e->input, msg_len);
 718         type = buffer_get_char(&e->request);
 719
 720         /* check wheter agent is locked */
 721         if (locked && type != SSH_AGENTC_UNLOCK) {
 722                 buffer_clear(&e->request);
 723                 switch (type) {
 724                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 725                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 726                         /* send empty lists */
 727                         no_identities(e, type);
 728                         break;
 729                 default:
 730                         /* send a fail message for all other request types */
 731                         buffer_put_int(&e->output, 1);
 732                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 733                 }
 734                 return;
 735         }
 736
 737         debug("type %d", type);
 738         switch (type) {
 739         case SSH_AGENTC_LOCK:
 740         case SSH_AGENTC_UNLOCK:
 741                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 742                 break;
 743         /* ssh1 */
 744         case SSH_AGENTC_RSA_CHALLENGE:
 745                 process_authentication_challenge1(e);
 746                 break;
 747         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 748                 process_request_identities(e, 1);
 749                 break;
 750         case SSH_AGENTC_ADD_RSA_IDENTITY:
 751         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 752                 process_add_identity(e, 1);
 753                 break;
 754         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 755                 process_remove_identity(e, 1);
 756                 break;
 757         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 758                 process_remove_all_identities(e, 1);
 759                 break;
 760         /* ssh2 */
 761         case SSH2_AGENTC_SIGN_REQUEST:
 762                 process_sign_request2(e);
 763                 break;
 764         case SSH2_AGENTC_REQUEST_IDENTITIES:
 765                 process_request_identities(e, 2);
 766                 break;
 767         case SSH2_AGENTC_ADD_IDENTITY:
 768         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 769                 process_add_identity(e, 2);
 770                 break;
 771         case SSH2_AGENTC_REMOVE_IDENTITY:
 772                 process_remove_identity(e, 2);
 773                 break;
 774         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 775                 process_remove_all_identities(e, 2);
 776                 break;
 777 #ifdef SMARTCARD
 778         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 779         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 780                 process_add_smartcard_key(e);
 781                 break;
 782         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 783                 process_remove_smartcard_key(e);
 784                 break;
 785 #endif /* SMARTCARD */
 786         default:
 787                 /* Unknown message.  Respond with failure. */
 788                 error("Unknown message %d", type);
 789                 buffer_clear(&e->request);
 790                 buffer_put_int(&e->output, 1);
 791                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 792                 break;
 793         }
 794 }
 795
 796 static void
 797 new_socket(sock_type type, int fd)
 798 {
 799         u_int i, old_alloc, new_alloc;
 800
 801         set_nonblock(fd);
 802
 803         if (fd > max_fd)
 804                 max_fd = fd;
 805
 806         for (i = 0; i < sockets_alloc; i++)
 807                 if (sockets[i].type == AUTH_UNUSED) {
 808                         sockets[i].fd = fd;
 809                         buffer_init(&sockets[i].input);
 810                         buffer_init(&sockets[i].output);
 811                         buffer_init(&sockets[i].request);
 812                         sockets[i].type = type;
 813                         return;
 814                 }
 815         old_alloc = sockets_alloc;
 816         new_alloc = sockets_alloc + 10;
 817         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 818         for (i = old_alloc; i < new_alloc; i++)
 819                 sockets[i].type = AUTH_UNUSED;
 820         sockets_alloc = new_alloc;
 821         sockets[old_alloc].fd = fd;
 822         buffer_init(&sockets[old_alloc].input);
 823         buffer_init(&sockets[old_alloc].output);
 824         buffer_init(&sockets[old_alloc].request);
 825         sockets[old_alloc].type = type;
 826 }
 827
 828 static int
 829 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
 830 {
 831         u_int i, sz;
 832         int n = 0;
 833
 834         for (i = 0; i < sockets_alloc; i++) {
 835                 switch (sockets[i].type) {
 836                 case AUTH_SOCKET:
 837                 case AUTH_CONNECTION:
 838                         n = MAX(n, sockets[i].fd);
 839                         break;
 840                 case AUTH_UNUSED:
 841                         break;
 842                 default:
 843                         fatal("Unknown socket type %d", sockets[i].type);
 844                         break;
 845                 }
 846         }
 847
 848         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 849         if (*fdrp == NULL || sz > *nallocp) {
 850                 if (*fdrp)
 851                         xfree(*fdrp);
 852                 if (*fdwp)
 853                         xfree(*fdwp);
 854                 *fdrp = xmalloc(sz);
 855                 *fdwp = xmalloc(sz);
 856                 *nallocp = sz;
 857         }
 858         if (n < *fdl)
 859                 debug("XXX shrink: %d < %d", n, *fdl);
 860         *fdl = n;
 861         memset(*fdrp, 0, sz);
 862         memset(*fdwp, 0, sz);
 863
 864         for (i = 0; i < sockets_alloc; i++) {
 865                 switch (sockets[i].type) {
 866                 case AUTH_SOCKET:
 867                 case AUTH_CONNECTION:
 868                         FD_SET(sockets[i].fd, *fdrp);
 869                         if (buffer_len(&sockets[i].output) > 0)
 870                                 FD_SET(sockets[i].fd, *fdwp);
 871                         break;
 872                 default:
 873                         break;
 874                 }
 875         }
 876         return (1);
 877 }
 878
 879 static void
 880 after_select(fd_set *readset, fd_set *writeset)
 881 {
 882         struct sockaddr_un sunaddr;
 883         socklen_t slen;
 884         char buf[1024];
 885         int len, sock;
 886         u_int i;
 887         uid_t euid;
 888         gid_t egid;
 889
 890         for (i = 0; i < sockets_alloc; i++)
 891                 switch (sockets[i].type) {
 892                 case AUTH_UNUSED:
 893                         break;
 894                 case AUTH_SOCKET:
 895                         if (FD_ISSET(sockets[i].fd, readset)) {
 896                                 slen = sizeof(sunaddr);
 897                                 sock = accept(sockets[i].fd,
 898                                     (struct sockaddr *)&sunaddr, &slen);
 899                                 if (sock < 0) {
 900                                         error("accept from AUTH_SOCKET: %s",
 901                                             strerror(errno));
 902                                         break;
 903                                 }
 904                                 if (getpeereid(sock, &euid, &egid) < 0) {
 905                                         error("getpeereid %d failed: %s",
 906                                             sock, strerror(errno));
 907                                         close(sock);
 908                                         break;
 909                                 }
 910                                 if ((euid != 0) && (getuid() != euid)) {
 911                                         error("uid mismatch: "
 912                                             "peer euid %u != uid %u",
 913                                             (u_int) euid, (u_int) getuid());
 914                                         close(sock);
 915                                         break;
 916                                 }
 917                                 new_socket(AUTH_CONNECTION, sock);
 918                         }
 919                         break;
 920                 case AUTH_CONNECTION:
 921                         if (buffer_len(&sockets[i].output) > 0 &&
 922                             FD_ISSET(sockets[i].fd, writeset)) {
 923                                 do {
 924                                         len = write(sockets[i].fd,
 925                                             buffer_ptr(&sockets[i].output),
 926                                             buffer_len(&sockets[i].output));
 927                                         if (len == -1 && (errno == EAGAIN ||
 928                                             errno == EINTR))
 929                                                 continue;
 930                                         break;
 931                                 } while (1);
 932                                 if (len <= 0) {
 933                                         close_socket(&sockets[i]);
 934                                         break;
 935                                 }
 936                                 buffer_consume(&sockets[i].output, len);
 937                         }
 938                         if (FD_ISSET(sockets[i].fd, readset)) {
 939                                 do {
 940                                         len = read(sockets[i].fd, buf, sizeof(buf));
 941                                         if (len == -1 && (errno == EAGAIN ||
 942                                             errno == EINTR))
 943                                                 continue;
 944                                         break;
 945                                 } while (1);
 946                                 if (len <= 0) {
 947                                         close_socket(&sockets[i]);
 948                                         break;
 949                                 }
 950                                 buffer_append(&sockets[i].input, buf, len);
 951                                 process_message(&sockets[i]);
 952                         }
 953                         break;
 954                 default:
 955                         fatal("Unknown type %d", sockets[i].type);
 956                 }
 957 }
 958
 959 static void
 960 cleanup_socket(void)
 961 {
 962         if (socket_name[0])
 963                 unlink(socket_name);
 964         if (socket_dir[0])
 965                 rmdir(socket_dir);
 966 }
 967
 968 void
 969 cleanup_exit(int i)
 970 {
 971         cleanup_socket();
 972         _exit(i);
 973 }
 974
 975 /*ARGSUSED*/
 976 static void
 977 cleanup_handler(int sig)
 978 {
 979         cleanup_socket();
 980         _exit(2);
 981 }
 982
 983 /*ARGSUSED*/
 984 static void
 985 check_parent_exists(int sig)
 986 {
 987         int save_errno = errno;
 988
 989         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 990                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 991                 cleanup_handler(sig); /* safe */
 992         }
 993         mysignal(SIGALRM, check_parent_exists);
 994         alarm(10);
 995         errno = save_errno;
 996 }
 997
 998 static void
 999 usage(void)
1000 {
1001         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
1002             __progname);
1003         fprintf(stderr, "Options:\n");
1004         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1005         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1006         fprintf(stderr, "  -k          Kill the current agent.\n");
1007         fprintf(stderr, "  -d          Debug mode.\n");
1008         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1009         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1010         exit(1);
1011 }
1012
1013 int
1014 main(int ac, char **av)
1015 {
1016         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1017         int sock, fd,  ch;
1018         u_int nalloc;
1019         char *shell, *format, *pidstr, *agentsocket = NULL;
1020         fd_set *readsetp = NULL, *writesetp = NULL;
1021         struct sockaddr_un sunaddr;
1022 #ifdef HAVE_SETRLIMIT
1023         struct rlimit rlim;
1024 #endif
1025         int prev_mask;
1026         extern int optind;
1027         extern char *optarg;
1028         pid_t pid;
1029         char pidstrbuf[1 + 3 * sizeof pid];
1030
1031         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1032         sanitise_stdfd();
1033
1034         /* drop */
1035         setegid(getgid());
1036         setgid(getgid());
1037
1038 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1039         /* Disable ptrace on Linux without sgid bit */
1040         prctl(PR_SET_DUMPABLE, 0);
1041 #endif
1042
1043         SSLeay_add_all_algorithms();
1044
1045         __progname = ssh_get_progname(av[0]);
1046         init_rng();
1047         seed_rng();
1048
1049         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1050                 switch (ch) {
1051                 case 'c':
1052                         if (s_flag)
1053                                 usage();
1054                         c_flag++;
1055                         break;
1056                 case 'k':
1057                         k_flag++;
1058                         break;
1059                 case 's':
1060                         if (c_flag)
1061                                 usage();
1062                         s_flag++;
1063                         break;
1064                 case 'd':
1065                         if (d_flag)
1066                                 usage();
1067                         d_flag++;
1068                         break;
1069                 case 'a':
1070                         agentsocket = optarg;
1071                         break;
1072                 case 't':
1073                         if ((lifetime = convtime(optarg)) == -1) {
1074                                 fprintf(stderr, "Invalid lifetime\n");
1075                                 usage();
1076                         }
1077                         break;
1078                 default:
1079                         usage();
1080                 }
1081         }
1082         ac -= optind;
1083         av += optind;
1084
1085         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1086                 usage();
1087
1088         if (ac == 0 && !c_flag && !s_flag) {
1089                 shell = getenv("SHELL");
1090                 if (shell != NULL &&
1091                     strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1092                         c_flag = 1;
1093         }
1094         if (k_flag) {
1095                 const char *errstr = NULL;
1096
1097                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1098                 if (pidstr == NULL) {
1099                         fprintf(stderr, "%s not set, cannot kill agent\n",
1100                             SSH_AGENTPID_ENV_NAME);
1101                         exit(1);
1102                 }
1103                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1104                 if (errstr) {
1105                         fprintf(stderr,
1106                             "%s=\"%s\", which is not a good PID: %s\n",
1107                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1108                         exit(1);
1109                 }
1110                 if (kill(pid, SIGTERM) == -1) {
1111                         perror("kill");
1112                         exit(1);
1113                 }
1114                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1115                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1116                 printf(format, SSH_AGENTPID_ENV_NAME);
1117                 printf("echo Agent pid %ld killed;\n", (long)pid);
1118                 exit(0);
1119         }
1120         parent_pid = getpid();
1121
1122         if (agentsocket == NULL) {
1123                 /* Create private directory for agent socket */
1124                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1125                 if (mkdtemp(socket_dir) == NULL) {
1126                         perror("mkdtemp: private socket dir");
1127                         exit(1);
1128                 }
1129                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1130                     (long)parent_pid);
1131         } else {
1132                 /* Try to use specified agent socket */
1133                 socket_dir[0] = '\0';
1134                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1135         }
1136
1137         /*
1138          * Create socket early so it will exist before command gets run from
1139          * the parent.
1140          */
1141         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1142         if (sock < 0) {
1143                 perror("socket");
1144                 *socket_name = '\0'; /* Don't unlink any existing file */
1145                 cleanup_exit(1);
1146         }
1147         memset(&sunaddr, 0, sizeof(sunaddr));
1148         sunaddr.sun_family = AF_UNIX;
1149         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1150         prev_mask = umask(0177);
1151         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1152                 perror("bind");
1153                 *socket_name = '\0'; /* Don't unlink any existing file */
1154                 umask(prev_mask);
1155                 cleanup_exit(1);
1156         }
1157         umask(prev_mask);
1158         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1159                 perror("listen");
1160                 cleanup_exit(1);
1161         }
1162
1163         /*
1164          * Fork, and have the parent execute the command, if any, or present
1165          * the socket data.  The child continues as the authentication agent.
1166          */
1167         if (d_flag) {
1168                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1169                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1170                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1171                     SSH_AUTHSOCKET_ENV_NAME);
1172                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1173                 goto skip;
1174         }
1175         pid = fork();
1176         if (pid == -1) {
1177                 perror("fork");
1178                 cleanup_exit(1);
1179         }
1180         if (pid != 0) {         /* Parent - execute the given command. */
1181                 close(sock);
1182                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1183                 if (ac == 0) {
1184                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1185                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1186                             SSH_AUTHSOCKET_ENV_NAME);
1187                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1188                             SSH_AGENTPID_ENV_NAME);
1189                         printf("echo Agent pid %ld;\n", (long)pid);
1190                         exit(0);
1191                 }
1192                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1193                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1194                         perror("setenv");
1195                         exit(1);
1196                 }
1197                 execvp(av[0], av);
1198                 perror(av[0]);
1199                 exit(1);
1200         }
1201         /* child */
1202         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1203
1204         if (setsid() == -1) {
1205                 error("setsid: %s", strerror(errno));
1206                 cleanup_exit(1);
1207         }
1208
1209         (void)chdir("/");
1210         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1211                 /* XXX might close listen socket */
1212                 (void)dup2(fd, STDIN_FILENO);
1213                 (void)dup2(fd, STDOUT_FILENO);
1214                 (void)dup2(fd, STDERR_FILENO);
1215                 if (fd > 2)
1216                         close(fd);
1217         }
1218
1219 #ifdef HAVE_SETRLIMIT
1220         /* deny core dumps, since memory contains unencrypted private keys */
1221         rlim.rlim_cur = rlim.rlim_max = 0;
1222         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1223                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1224                 cleanup_exit(1);
1225         }
1226 #endif
1227
1228 skip:
1229         new_socket(AUTH_SOCKET, sock);
1230         if (ac > 0) {
1231                 mysignal(SIGALRM, check_parent_exists);
1232                 alarm(10);
1233         }
1234         idtab_init();
1235         if (!d_flag)
1236                 signal(SIGINT, SIG_IGN);
1237         signal(SIGPIPE, SIG_IGN);
1238         signal(SIGHUP, cleanup_handler);
1239         signal(SIGTERM, cleanup_handler);
1240         nalloc = 0;
1241
1242         while (1) {
1243                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1244                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1245                         if (errno == EINTR)
1246                                 continue;
1247                         fatal("select: %s", strerror(errno));
1248                 }
1249                 after_select(readsetp, writesetp);
1250         }
1251         /* NOTREACHED */
1252 }