ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.143 2006/07/11 20:07:25 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/stat.h>
  41 #include <sys/socket.h>
  42 #ifdef HAVE_SYS_UN_H
  43 # include <sys/un.h>
  44 #endif
  45 #include "openbsd-compat/sys-queue.h"
  46 #include <sys/resource.h>
  47
  48 #include <errno.h>
  49 #include <fcntl.h>
  50 #ifdef HAVE_PATHS_H
  51 # include <paths.h>
  52 #endif
  53 #include <signal.h>
  54
  55 #include <openssl/evp.h>
  56 #include <openssl/md5.h>
  57
  58 #include "ssh.h"
  59 #include "rsa.h"
  60 #include "buffer.h"
  61 #include "bufaux.h"
  62 #include "xmalloc.h"
  63 #include "key.h"
  64 #include "authfd.h"
  65 #include "compat.h"
  66 #include "log.h"
  67 #include "misc.h"
  68
  69 #ifdef SMARTCARD
  70 #include "scard.h"
  71 #endif
  72
  73 #if defined(HAVE_SYS_PRCTL_H)
  74 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  75 #endif
  76
  77 typedef enum {
  78         AUTH_UNUSED,
  79         AUTH_SOCKET,
  80         AUTH_CONNECTION
  81 } sock_type;
  82
  83 typedef struct {
  84         int fd;
  85         sock_type type;
  86         Buffer input;
  87         Buffer output;
  88         Buffer request;
  89 } SocketEntry;
  90
  91 u_int sockets_alloc = 0;
  92 SocketEntry *sockets = NULL;
  93
  94 typedef struct identity {
  95         TAILQ_ENTRY(identity) next;
  96         Key *key;
  97         char *comment;
  98         u_int death;
  99         u_int confirm;
 100 } Identity;
 101
 102 typedef struct {
 103         int nentries;
 104         TAILQ_HEAD(idqueue, identity) idlist;
 105 } Idtab;
 106
 107 /* private key table, one per protocol version */
 108 Idtab idtable[3];
 109
 110 int max_fd = 0;
 111
 112 /* pid of shell == parent of agent */
 113 pid_t parent_pid = -1;
 114
 115 /* pathname and directory for AUTH_SOCKET */
 116 char socket_name[MAXPATHLEN];
 117 char socket_dir[MAXPATHLEN];
 118
 119 /* locking */
 120 int locked = 0;
 121 char *lock_passwd = NULL;
 122
 123 extern char *__progname;
 124
 125 /* Default lifetime (0 == forever) */
 126 static int lifetime = 0;
 127
 128 static void
 129 close_socket(SocketEntry *e)
 130 {
 131         close(e->fd);
 132         e->fd = -1;
 133         e->type = AUTH_UNUSED;
 134         buffer_free(&e->input);
 135         buffer_free(&e->output);
 136         buffer_free(&e->request);
 137 }
 138
 139 static void
 140 idtab_init(void)
 141 {
 142         int i;
 143
 144         for (i = 0; i <=2; i++) {
 145                 TAILQ_INIT(&idtable[i].idlist);
 146                 idtable[i].nentries = 0;
 147         }
 148 }
 149
 150 /* return private key table for requested protocol version */
 151 static Idtab *
 152 idtab_lookup(int version)
 153 {
 154         if (version < 1 || version > 2)
 155                 fatal("internal error, bad protocol version %d", version);
 156         return &idtable[version];
 157 }
 158
 159 static void
 160 free_identity(Identity *id)
 161 {
 162         key_free(id->key);
 163         xfree(id->comment);
 164         xfree(id);
 165 }
 166
 167 /* return matching private key for given public key */
 168 static Identity *
 169 lookup_identity(Key *key, int version)
 170 {
 171         Identity *id;
 172
 173         Idtab *tab = idtab_lookup(version);
 174         TAILQ_FOREACH(id, &tab->idlist, next) {
 175                 if (key_equal(key, id->key))
 176                         return (id);
 177         }
 178         return (NULL);
 179 }
 180
 181 /* Check confirmation of keysign request */
 182 static int
 183 confirm_key(Identity *id)
 184 {
 185         char *p;
 186         int ret = -1;
 187
 188         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 189         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 190             id->comment, p))
 191                 ret = 0;
 192         xfree(p);
 193
 194         return (ret);
 195 }
 196
 197 /* send list of supported public keys to 'client' */
 198 static void
 199 process_request_identities(SocketEntry *e, int version)
 200 {
 201         Idtab *tab = idtab_lookup(version);
 202         Identity *id;
 203         Buffer msg;
 204
 205         buffer_init(&msg);
 206         buffer_put_char(&msg, (version == 1) ?
 207             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 208         buffer_put_int(&msg, tab->nentries);
 209         TAILQ_FOREACH(id, &tab->idlist, next) {
 210                 if (id->key->type == KEY_RSA1) {
 211                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 212                         buffer_put_bignum(&msg, id->key->rsa->e);
 213                         buffer_put_bignum(&msg, id->key->rsa->n);
 214                 } else {
 215                         u_char *blob;
 216                         u_int blen;
 217                         key_to_blob(id->key, &blob, &blen);
 218                         buffer_put_string(&msg, blob, blen);
 219                         xfree(blob);
 220                 }
 221                 buffer_put_cstring(&msg, id->comment);
 222         }
 223         buffer_put_int(&e->output, buffer_len(&msg));
 224         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 225         buffer_free(&msg);
 226 }
 227
 228 /* ssh1 only */
 229 static void
 230 process_authentication_challenge1(SocketEntry *e)
 231 {
 232         u_char buf[32], mdbuf[16], session_id[16];
 233         u_int response_type;
 234         BIGNUM *challenge;
 235         Identity *id;
 236         int i, len;
 237         Buffer msg;
 238         MD5_CTX md;
 239         Key *key;
 240
 241         buffer_init(&msg);
 242         key = key_new(KEY_RSA1);
 243         if ((challenge = BN_new()) == NULL)
 244                 fatal("process_authentication_challenge1: BN_new failed");
 245
 246         (void) buffer_get_int(&e->request);                     /* ignored */
 247         buffer_get_bignum(&e->request, key->rsa->e);
 248         buffer_get_bignum(&e->request, key->rsa->n);
 249         buffer_get_bignum(&e->request, challenge);
 250
 251         /* Only protocol 1.1 is supported */
 252         if (buffer_len(&e->request) == 0)
 253                 goto failure;
 254         buffer_get(&e->request, session_id, 16);
 255         response_type = buffer_get_int(&e->request);
 256         if (response_type != 1)
 257                 goto failure;
 258
 259         id = lookup_identity(key, 1);
 260         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 261                 Key *private = id->key;
 262                 /* Decrypt the challenge using the private key. */
 263                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 264                         goto failure;
 265
 266                 /* The response is MD5 of decrypted challenge plus session id. */
 267                 len = BN_num_bytes(challenge);
 268                 if (len <= 0 || len > 32) {
 269                         logit("process_authentication_challenge: bad challenge length %d", len);
 270                         goto failure;
 271                 }
 272                 memset(buf, 0, 32);
 273                 BN_bn2bin(challenge, buf + 32 - len);
 274                 MD5_Init(&md);
 275                 MD5_Update(&md, buf, 32);
 276                 MD5_Update(&md, session_id, 16);
 277                 MD5_Final(mdbuf, &md);
 278
 279                 /* Send the response. */
 280                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 281                 for (i = 0; i < 16; i++)
 282                         buffer_put_char(&msg, mdbuf[i]);
 283                 goto send;
 284         }
 285
 286 failure:
 287         /* Unknown identity or protocol error.  Send failure. */
 288         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 289 send:
 290         buffer_put_int(&e->output, buffer_len(&msg));
 291         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 292         key_free(key);
 293         BN_clear_free(challenge);
 294         buffer_free(&msg);
 295 }
 296
 297 /* ssh2 only */
 298 static void
 299 process_sign_request2(SocketEntry *e)
 300 {
 301         u_char *blob, *data, *signature = NULL;
 302         u_int blen, dlen, slen = 0;
 303         extern int datafellows;
 304         int ok = -1, flags;
 305         Buffer msg;
 306         Key *key;
 307
 308         datafellows = 0;
 309
 310         blob = buffer_get_string(&e->request, &blen);
 311         data = buffer_get_string(&e->request, &dlen);
 312
 313         flags = buffer_get_int(&e->request);
 314         if (flags & SSH_AGENT_OLD_SIGNATURE)
 315                 datafellows = SSH_BUG_SIGBLOB;
 316
 317         key = key_from_blob(blob, blen);
 318         if (key != NULL) {
 319                 Identity *id = lookup_identity(key, 2);
 320                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 321                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 322                 key_free(key);
 323         }
 324         buffer_init(&msg);
 325         if (ok == 0) {
 326                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 327                 buffer_put_string(&msg, signature, slen);
 328         } else {
 329                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 330         }
 331         buffer_put_int(&e->output, buffer_len(&msg));
 332         buffer_append(&e->output, buffer_ptr(&msg),
 333             buffer_len(&msg));
 334         buffer_free(&msg);
 335         xfree(data);
 336         xfree(blob);
 337         if (signature != NULL)
 338                 xfree(signature);
 339 }
 340
 341 /* shared */
 342 static void
 343 process_remove_identity(SocketEntry *e, int version)
 344 {
 345         u_int blen, bits;
 346         int success = 0;
 347         Key *key = NULL;
 348         u_char *blob;
 349
 350         switch (version) {
 351         case 1:
 352                 key = key_new(KEY_RSA1);
 353                 bits = buffer_get_int(&e->request);
 354                 buffer_get_bignum(&e->request, key->rsa->e);
 355                 buffer_get_bignum(&e->request, key->rsa->n);
 356
 357                 if (bits != key_size(key))
 358                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 359                             key_size(key), bits);
 360                 break;
 361         case 2:
 362                 blob = buffer_get_string(&e->request, &blen);
 363                 key = key_from_blob(blob, blen);
 364                 xfree(blob);
 365                 break;
 366         }
 367         if (key != NULL) {
 368                 Identity *id = lookup_identity(key, version);
 369                 if (id != NULL) {
 370                         /*
 371                          * We have this key.  Free the old key.  Since we
 372                          * don't want to leave empty slots in the middle of
 373                          * the array, we actually free the key there and move
 374                          * all the entries between the empty slot and the end
 375                          * of the array.
 376                          */
 377                         Idtab *tab = idtab_lookup(version);
 378                         if (tab->nentries < 1)
 379                                 fatal("process_remove_identity: "
 380                                     "internal error: tab->nentries %d",
 381                                     tab->nentries);
 382                         TAILQ_REMOVE(&tab->idlist, id, next);
 383                         free_identity(id);
 384                         tab->nentries--;
 385                         success = 1;
 386                 }
 387                 key_free(key);
 388         }
 389         buffer_put_int(&e->output, 1);
 390         buffer_put_char(&e->output,
 391             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 392 }
 393
 394 static void
 395 process_remove_all_identities(SocketEntry *e, int version)
 396 {
 397         Idtab *tab = idtab_lookup(version);
 398         Identity *id;
 399
 400         /* Loop over all identities and clear the keys. */
 401         for (id = TAILQ_FIRST(&tab->idlist); id;
 402             id = TAILQ_FIRST(&tab->idlist)) {
 403                 TAILQ_REMOVE(&tab->idlist, id, next);
 404                 free_identity(id);
 405         }
 406
 407         /* Mark that there are no identities. */
 408         tab->nentries = 0;
 409
 410         /* Send success. */
 411         buffer_put_int(&e->output, 1);
 412         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 413 }
 414
 415 static void
 416 reaper(void)
 417 {
 418         u_int now = time(NULL);
 419         Identity *id, *nxt;
 420         int version;
 421         Idtab *tab;
 422
 423         for (version = 1; version < 3; version++) {
 424                 tab = idtab_lookup(version);
 425                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 426                         nxt = TAILQ_NEXT(id, next);
 427                         if (id->death != 0 && now >= id->death) {
 428                                 TAILQ_REMOVE(&tab->idlist, id, next);
 429                                 free_identity(id);
 430                                 tab->nentries--;
 431                         }
 432                 }
 433         }
 434 }
 435
 436 static void
 437 process_add_identity(SocketEntry *e, int version)
 438 {
 439         Idtab *tab = idtab_lookup(version);
 440         int type, success = 0, death = 0, confirm = 0;
 441         char *type_name, *comment;
 442         Key *k = NULL;
 443
 444         switch (version) {
 445         case 1:
 446                 k = key_new_private(KEY_RSA1);
 447                 (void) buffer_get_int(&e->request);             /* ignored */
 448                 buffer_get_bignum(&e->request, k->rsa->n);
 449                 buffer_get_bignum(&e->request, k->rsa->e);
 450                 buffer_get_bignum(&e->request, k->rsa->d);
 451                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 452
 453                 /* SSH and SSL have p and q swapped */
 454                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 455                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 456
 457                 /* Generate additional parameters */
 458                 rsa_generate_additional_parameters(k->rsa);
 459                 break;
 460         case 2:
 461                 type_name = buffer_get_string(&e->request, NULL);
 462                 type = key_type_from_name(type_name);
 463                 xfree(type_name);
 464                 switch (type) {
 465                 case KEY_DSA:
 466                         k = key_new_private(type);
 467                         buffer_get_bignum2(&e->request, k->dsa->p);
 468                         buffer_get_bignum2(&e->request, k->dsa->q);
 469                         buffer_get_bignum2(&e->request, k->dsa->g);
 470                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 471                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 472                         break;
 473                 case KEY_RSA:
 474                         k = key_new_private(type);
 475                         buffer_get_bignum2(&e->request, k->rsa->n);
 476                         buffer_get_bignum2(&e->request, k->rsa->e);
 477                         buffer_get_bignum2(&e->request, k->rsa->d);
 478                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 479                         buffer_get_bignum2(&e->request, k->rsa->p);
 480                         buffer_get_bignum2(&e->request, k->rsa->q);
 481
 482                         /* Generate additional parameters */
 483                         rsa_generate_additional_parameters(k->rsa);
 484                         break;
 485                 default:
 486                         buffer_clear(&e->request);
 487                         goto send;
 488                 }
 489                 break;
 490         }
 491         /* enable blinding */
 492         switch (k->type) {
 493         case KEY_RSA:
 494         case KEY_RSA1:
 495                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 496                         error("process_add_identity: RSA_blinding_on failed");
 497                         key_free(k);
 498                         goto send;
 499                 }
 500                 break;
 501         }
 502         comment = buffer_get_string(&e->request, NULL);
 503         if (k == NULL) {
 504                 xfree(comment);
 505                 goto send;
 506         }
 507         success = 1;
 508         while (buffer_len(&e->request)) {
 509                 switch (buffer_get_char(&e->request)) {
 510                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 511                         death = time(NULL) + buffer_get_int(&e->request);
 512                         break;
 513                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 514                         confirm = 1;
 515                         break;
 516                 default:
 517                         break;
 518                 }
 519         }
 520         if (lifetime && !death)
 521                 death = time(NULL) + lifetime;
 522         if (lookup_identity(k, version) == NULL) {
 523                 Identity *id = xmalloc(sizeof(Identity));
 524                 id->key = k;
 525                 id->comment = comment;
 526                 id->death = death;
 527                 id->confirm = confirm;
 528                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 529                 /* Increment the number of identities. */
 530                 tab->nentries++;
 531         } else {
 532                 key_free(k);
 533                 xfree(comment);
 534         }
 535 send:
 536         buffer_put_int(&e->output, 1);
 537         buffer_put_char(&e->output,
 538             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 539 }
 540
 541 /* XXX todo: encrypt sensitive data with passphrase */
 542 static void
 543 process_lock_agent(SocketEntry *e, int lock)
 544 {
 545         int success = 0;
 546         char *passwd;
 547
 548         passwd = buffer_get_string(&e->request, NULL);
 549         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 550                 locked = 0;
 551                 memset(lock_passwd, 0, strlen(lock_passwd));
 552                 xfree(lock_passwd);
 553                 lock_passwd = NULL;
 554                 success = 1;
 555         } else if (!locked && lock) {
 556                 locked = 1;
 557                 lock_passwd = xstrdup(passwd);
 558                 success = 1;
 559         }
 560         memset(passwd, 0, strlen(passwd));
 561         xfree(passwd);
 562
 563         buffer_put_int(&e->output, 1);
 564         buffer_put_char(&e->output,
 565             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 566 }
 567
 568 static void
 569 no_identities(SocketEntry *e, u_int type)
 570 {
 571         Buffer msg;
 572
 573         buffer_init(&msg);
 574         buffer_put_char(&msg,
 575             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 576             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 577         buffer_put_int(&msg, 0);
 578         buffer_put_int(&e->output, buffer_len(&msg));
 579         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 580         buffer_free(&msg);
 581 }
 582
 583 #ifdef SMARTCARD
 584 static void
 585 process_add_smartcard_key (SocketEntry *e)
 586 {
 587         char *sc_reader_id = NULL, *pin;
 588         int i, version, success = 0, death = 0, confirm = 0;
 589         Key **keys, *k;
 590         Identity *id;
 591         Idtab *tab;
 592
 593         sc_reader_id = buffer_get_string(&e->request, NULL);
 594         pin = buffer_get_string(&e->request, NULL);
 595
 596         while (buffer_len(&e->request)) {
 597                 switch (buffer_get_char(&e->request)) {
 598                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 599                         death = time(NULL) + buffer_get_int(&e->request);
 600                         break;
 601                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 602                         confirm = 1;
 603                         break;
 604                 default:
 605                         break;
 606                 }
 607         }
 608         if (lifetime && !death)
 609                 death = time(NULL) + lifetime;
 610
 611         keys = sc_get_keys(sc_reader_id, pin);
 612         xfree(sc_reader_id);
 613         xfree(pin);
 614
 615         if (keys == NULL || keys[0] == NULL) {
 616                 error("sc_get_keys failed");
 617                 goto send;
 618         }
 619         for (i = 0; keys[i] != NULL; i++) {
 620                 k = keys[i];
 621                 version = k->type == KEY_RSA1 ? 1 : 2;
 622                 tab = idtab_lookup(version);
 623                 if (lookup_identity(k, version) == NULL) {
 624                         id = xmalloc(sizeof(Identity));
 625                         id->key = k;
 626                         id->comment = sc_get_key_label(k);
 627                         id->death = death;
 628                         id->confirm = confirm;
 629                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 630                         tab->nentries++;
 631                         success = 1;
 632                 } else {
 633                         key_free(k);
 634                 }
 635                 keys[i] = NULL;
 636         }
 637         xfree(keys);
 638 send:
 639         buffer_put_int(&e->output, 1);
 640         buffer_put_char(&e->output,
 641             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 642 }
 643
 644 static void
 645 process_remove_smartcard_key(SocketEntry *e)
 646 {
 647         char *sc_reader_id = NULL, *pin;
 648         int i, version, success = 0;
 649         Key **keys, *k = NULL;
 650         Identity *id;
 651         Idtab *tab;
 652
 653         sc_reader_id = buffer_get_string(&e->request, NULL);
 654         pin = buffer_get_string(&e->request, NULL);
 655         keys = sc_get_keys(sc_reader_id, pin);
 656         xfree(sc_reader_id);
 657         xfree(pin);
 658
 659         if (keys == NULL || keys[0] == NULL) {
 660                 error("sc_get_keys failed");
 661                 goto send;
 662         }
 663         for (i = 0; keys[i] != NULL; i++) {
 664                 k = keys[i];
 665                 version = k->type == KEY_RSA1 ? 1 : 2;
 666                 if ((id = lookup_identity(k, version)) != NULL) {
 667                         tab = idtab_lookup(version);
 668                         TAILQ_REMOVE(&tab->idlist, id, next);
 669                         tab->nentries--;
 670                         free_identity(id);
 671                         success = 1;
 672                 }
 673                 key_free(k);
 674                 keys[i] = NULL;
 675         }
 676         xfree(keys);
 677 send:
 678         buffer_put_int(&e->output, 1);
 679         buffer_put_char(&e->output,
 680             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 681 }
 682 #endif /* SMARTCARD */
 683
 684 /* dispatch incoming messages */
 685
 686 static void
 687 process_message(SocketEntry *e)
 688 {
 689         u_int msg_len, type;
 690         u_char *cp;
 691
 692         /* kill dead keys */
 693         reaper();
 694
 695         if (buffer_len(&e->input) < 5)
 696                 return;         /* Incomplete message. */
 697         cp = buffer_ptr(&e->input);
 698         msg_len = get_u32(cp);
 699         if (msg_len > 256 * 1024) {
 700                 close_socket(e);
 701                 return;
 702         }
 703         if (buffer_len(&e->input) < msg_len + 4)
 704                 return;
 705
 706         /* move the current input to e->request */
 707         buffer_consume(&e->input, 4);
 708         buffer_clear(&e->request);
 709         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 710         buffer_consume(&e->input, msg_len);
 711         type = buffer_get_char(&e->request);
 712
 713         /* check wheter agent is locked */
 714         if (locked && type != SSH_AGENTC_UNLOCK) {
 715                 buffer_clear(&e->request);
 716                 switch (type) {
 717                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 718                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 719                         /* send empty lists */
 720                         no_identities(e, type);
 721                         break;
 722                 default:
 723                         /* send a fail message for all other request types */
 724                         buffer_put_int(&e->output, 1);
 725                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 726                 }
 727                 return;
 728         }
 729
 730         debug("type %d", type);
 731         switch (type) {
 732         case SSH_AGENTC_LOCK:
 733         case SSH_AGENTC_UNLOCK:
 734                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 735                 break;
 736         /* ssh1 */
 737         case SSH_AGENTC_RSA_CHALLENGE:
 738                 process_authentication_challenge1(e);
 739                 break;
 740         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 741                 process_request_identities(e, 1);
 742                 break;
 743         case SSH_AGENTC_ADD_RSA_IDENTITY:
 744         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 745                 process_add_identity(e, 1);
 746                 break;
 747         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 748                 process_remove_identity(e, 1);
 749                 break;
 750         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 751                 process_remove_all_identities(e, 1);
 752                 break;
 753         /* ssh2 */
 754         case SSH2_AGENTC_SIGN_REQUEST:
 755                 process_sign_request2(e);
 756                 break;
 757         case SSH2_AGENTC_REQUEST_IDENTITIES:
 758                 process_request_identities(e, 2);
 759                 break;
 760         case SSH2_AGENTC_ADD_IDENTITY:
 761         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 762                 process_add_identity(e, 2);
 763                 break;
 764         case SSH2_AGENTC_REMOVE_IDENTITY:
 765                 process_remove_identity(e, 2);
 766                 break;
 767         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 768                 process_remove_all_identities(e, 2);
 769                 break;
 770 #ifdef SMARTCARD
 771         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 772         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 773                 process_add_smartcard_key(e);
 774                 break;
 775         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 776                 process_remove_smartcard_key(e);
 777                 break;
 778 #endif /* SMARTCARD */
 779         default:
 780                 /* Unknown message.  Respond with failure. */
 781                 error("Unknown message %d", type);
 782                 buffer_clear(&e->request);
 783                 buffer_put_int(&e->output, 1);
 784                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 785                 break;
 786         }
 787 }
 788
 789 static void
 790 new_socket(sock_type type, int fd)
 791 {
 792         u_int i, old_alloc, new_alloc;
 793
 794         set_nonblock(fd);
 795
 796         if (fd > max_fd)
 797                 max_fd = fd;
 798
 799         for (i = 0; i < sockets_alloc; i++)
 800                 if (sockets[i].type == AUTH_UNUSED) {
 801                         sockets[i].fd = fd;
 802                         buffer_init(&sockets[i].input);
 803                         buffer_init(&sockets[i].output);
 804                         buffer_init(&sockets[i].request);
 805                         sockets[i].type = type;
 806                         return;
 807                 }
 808         old_alloc = sockets_alloc;
 809         new_alloc = sockets_alloc + 10;
 810         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 811         for (i = old_alloc; i < new_alloc; i++)
 812                 sockets[i].type = AUTH_UNUSED;
 813         sockets_alloc = new_alloc;
 814         sockets[old_alloc].fd = fd;
 815         buffer_init(&sockets[old_alloc].input);
 816         buffer_init(&sockets[old_alloc].output);
 817         buffer_init(&sockets[old_alloc].request);
 818         sockets[old_alloc].type = type;
 819 }
 820
 821 static int
 822 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
 823 {
 824         u_int i, sz;
 825         int n = 0;
 826
 827         for (i = 0; i < sockets_alloc; i++) {
 828                 switch (sockets[i].type) {
 829                 case AUTH_SOCKET:
 830                 case AUTH_CONNECTION:
 831                         n = MAX(n, sockets[i].fd);
 832                         break;
 833                 case AUTH_UNUSED:
 834                         break;
 835                 default:
 836                         fatal("Unknown socket type %d", sockets[i].type);
 837                         break;
 838                 }
 839         }
 840
 841         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 842         if (*fdrp == NULL || sz > *nallocp) {
 843                 if (*fdrp)
 844                         xfree(*fdrp);
 845                 if (*fdwp)
 846                         xfree(*fdwp);
 847                 *fdrp = xmalloc(sz);
 848                 *fdwp = xmalloc(sz);
 849                 *nallocp = sz;
 850         }
 851         if (n < *fdl)
 852                 debug("XXX shrink: %d < %d", n, *fdl);
 853         *fdl = n;
 854         memset(*fdrp, 0, sz);
 855         memset(*fdwp, 0, sz);
 856
 857         for (i = 0; i < sockets_alloc; i++) {
 858                 switch (sockets[i].type) {
 859                 case AUTH_SOCKET:
 860                 case AUTH_CONNECTION:
 861                         FD_SET(sockets[i].fd, *fdrp);
 862                         if (buffer_len(&sockets[i].output) > 0)
 863                                 FD_SET(sockets[i].fd, *fdwp);
 864                         break;
 865                 default:
 866                         break;
 867                 }
 868         }
 869         return (1);
 870 }
 871
 872 static void
 873 after_select(fd_set *readset, fd_set *writeset)
 874 {
 875         struct sockaddr_un sunaddr;
 876         socklen_t slen;
 877         char buf[1024];
 878         int len, sock;
 879         u_int i;
 880         uid_t euid;
 881         gid_t egid;
 882
 883         for (i = 0; i < sockets_alloc; i++)
 884                 switch (sockets[i].type) {
 885                 case AUTH_UNUSED:
 886                         break;
 887                 case AUTH_SOCKET:
 888                         if (FD_ISSET(sockets[i].fd, readset)) {
 889                                 slen = sizeof(sunaddr);
 890                                 sock = accept(sockets[i].fd,
 891                                     (struct sockaddr *)&sunaddr, &slen);
 892                                 if (sock < 0) {
 893                                         error("accept from AUTH_SOCKET: %s",
 894                                             strerror(errno));
 895                                         break;
 896                                 }
 897                                 if (getpeereid(sock, &euid, &egid) < 0) {
 898                                         error("getpeereid %d failed: %s",
 899                                             sock, strerror(errno));
 900                                         close(sock);
 901                                         break;
 902                                 }
 903                                 if ((euid != 0) && (getuid() != euid)) {
 904                                         error("uid mismatch: "
 905                                             "peer euid %u != uid %u",
 906                                             (u_int) euid, (u_int) getuid());
 907                                         close(sock);
 908                                         break;
 909                                 }
 910                                 new_socket(AUTH_CONNECTION, sock);
 911                         }
 912                         break;
 913                 case AUTH_CONNECTION:
 914                         if (buffer_len(&sockets[i].output) > 0 &&
 915                             FD_ISSET(sockets[i].fd, writeset)) {
 916                                 do {
 917                                         len = write(sockets[i].fd,
 918                                             buffer_ptr(&sockets[i].output),
 919                                             buffer_len(&sockets[i].output));
 920                                         if (len == -1 && (errno == EAGAIN ||
 921                                             errno == EINTR))
 922                                                 continue;
 923                                         break;
 924                                 } while (1);
 925                                 if (len <= 0) {
 926                                         close_socket(&sockets[i]);
 927                                         break;
 928                                 }
 929                                 buffer_consume(&sockets[i].output, len);
 930                         }
 931                         if (FD_ISSET(sockets[i].fd, readset)) {
 932                                 do {
 933                                         len = read(sockets[i].fd, buf, sizeof(buf));
 934                                         if (len == -1 && (errno == EAGAIN ||
 935                                             errno == EINTR))
 936                                                 continue;
 937                                         break;
 938                                 } while (1);
 939                                 if (len <= 0) {
 940                                         close_socket(&sockets[i]);
 941                                         break;
 942                                 }
 943                                 buffer_append(&sockets[i].input, buf, len);
 944                                 process_message(&sockets[i]);
 945                         }
 946                         break;
 947                 default:
 948                         fatal("Unknown type %d", sockets[i].type);
 949                 }
 950 }
 951
 952 static void
 953 cleanup_socket(void)
 954 {
 955         if (socket_name[0])
 956                 unlink(socket_name);
 957         if (socket_dir[0])
 958                 rmdir(socket_dir);
 959 }
 960
 961 void
 962 cleanup_exit(int i)
 963 {
 964         cleanup_socket();
 965         _exit(i);
 966 }
 967
 968 /*ARGSUSED*/
 969 static void
 970 cleanup_handler(int sig)
 971 {
 972         cleanup_socket();
 973         _exit(2);
 974 }
 975
 976 /*ARGSUSED*/
 977 static void
 978 check_parent_exists(int sig)
 979 {
 980         int save_errno = errno;
 981
 982         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 983                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 984                 cleanup_handler(sig); /* safe */
 985         }
 986         mysignal(SIGALRM, check_parent_exists);
 987         alarm(10);
 988         errno = save_errno;
 989 }
 990
 991 static void
 992 usage(void)
 993 {
 994         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 995             __progname);
 996         fprintf(stderr, "Options:\n");
 997         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 998         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 999         fprintf(stderr, "  -k          Kill the current agent.\n");
1000         fprintf(stderr, "  -d          Debug mode.\n");
1001         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1002         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1003         exit(1);
1004 }
1005
1006 int
1007 main(int ac, char **av)
1008 {
1009         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1010         int sock, fd,  ch;
1011         u_int nalloc;
1012         char *shell, *format, *pidstr, *agentsocket = NULL;
1013         fd_set *readsetp = NULL, *writesetp = NULL;
1014         struct sockaddr_un sunaddr;
1015 #ifdef HAVE_SETRLIMIT
1016         struct rlimit rlim;
1017 #endif
1018         int prev_mask;
1019         extern int optind;
1020         extern char *optarg;
1021         pid_t pid;
1022         char pidstrbuf[1 + 3 * sizeof pid];
1023
1024         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1025         sanitise_stdfd();
1026
1027         /* drop */
1028         setegid(getgid());
1029         setgid(getgid());
1030
1031 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1032         /* Disable ptrace on Linux without sgid bit */
1033         prctl(PR_SET_DUMPABLE, 0);
1034 #endif
1035
1036         SSLeay_add_all_algorithms();
1037
1038         __progname = ssh_get_progname(av[0]);
1039         init_rng();
1040         seed_rng();
1041
1042         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1043                 switch (ch) {
1044                 case 'c':
1045                         if (s_flag)
1046                                 usage();
1047                         c_flag++;
1048                         break;
1049                 case 'k':
1050                         k_flag++;
1051                         break;
1052                 case 's':
1053                         if (c_flag)
1054                                 usage();
1055                         s_flag++;
1056                         break;
1057                 case 'd':
1058                         if (d_flag)
1059                                 usage();
1060                         d_flag++;
1061                         break;
1062                 case 'a':
1063                         agentsocket = optarg;
1064                         break;
1065                 case 't':
1066                         if ((lifetime = convtime(optarg)) == -1) {
1067                                 fprintf(stderr, "Invalid lifetime\n");
1068                                 usage();
1069                         }
1070                         break;
1071                 default:
1072                         usage();
1073                 }
1074         }
1075         ac -= optind;
1076         av += optind;
1077
1078         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1079                 usage();
1080
1081         if (ac == 0 && !c_flag && !s_flag) {
1082                 shell = getenv("SHELL");
1083                 if (shell != NULL &&
1084                     strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1085                         c_flag = 1;
1086         }
1087         if (k_flag) {
1088                 const char *errstr = NULL;
1089
1090                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1091                 if (pidstr == NULL) {
1092                         fprintf(stderr, "%s not set, cannot kill agent\n",
1093                             SSH_AGENTPID_ENV_NAME);
1094                         exit(1);
1095                 }
1096                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1097                 if (errstr) {
1098                         fprintf(stderr,
1099                             "%s=\"%s\", which is not a good PID: %s\n",
1100                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1101                         exit(1);
1102                 }
1103                 if (kill(pid, SIGTERM) == -1) {
1104                         perror("kill");
1105                         exit(1);
1106                 }
1107                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1108                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1109                 printf(format, SSH_AGENTPID_ENV_NAME);
1110                 printf("echo Agent pid %ld killed;\n", (long)pid);
1111                 exit(0);
1112         }
1113         parent_pid = getpid();
1114
1115         if (agentsocket == NULL) {
1116                 /* Create private directory for agent socket */
1117                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1118                 if (mkdtemp(socket_dir) == NULL) {
1119                         perror("mkdtemp: private socket dir");
1120                         exit(1);
1121                 }
1122                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1123                     (long)parent_pid);
1124         } else {
1125                 /* Try to use specified agent socket */
1126                 socket_dir[0] = '\0';
1127                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1128         }
1129
1130         /*
1131          * Create socket early so it will exist before command gets run from
1132          * the parent.
1133          */
1134         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1135         if (sock < 0) {
1136                 perror("socket");
1137                 *socket_name = '\0'; /* Don't unlink any existing file */
1138                 cleanup_exit(1);
1139         }
1140         memset(&sunaddr, 0, sizeof(sunaddr));
1141         sunaddr.sun_family = AF_UNIX;
1142         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1143         prev_mask = umask(0177);
1144         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1145                 perror("bind");
1146                 *socket_name = '\0'; /* Don't unlink any existing file */
1147                 umask(prev_mask);
1148                 cleanup_exit(1);
1149         }
1150         umask(prev_mask);
1151         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1152                 perror("listen");
1153                 cleanup_exit(1);
1154         }
1155
1156         /*
1157          * Fork, and have the parent execute the command, if any, or present
1158          * the socket data.  The child continues as the authentication agent.
1159          */
1160         if (d_flag) {
1161                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1162                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1163                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1164                     SSH_AUTHSOCKET_ENV_NAME);
1165                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1166                 goto skip;
1167         }
1168         pid = fork();
1169         if (pid == -1) {
1170                 perror("fork");
1171                 cleanup_exit(1);
1172         }
1173         if (pid != 0) {         /* Parent - execute the given command. */
1174                 close(sock);
1175                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1176                 if (ac == 0) {
1177                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1178                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1179                             SSH_AUTHSOCKET_ENV_NAME);
1180                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1181                             SSH_AGENTPID_ENV_NAME);
1182                         printf("echo Agent pid %ld;\n", (long)pid);
1183                         exit(0);
1184                 }
1185                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1186                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1187                         perror("setenv");
1188                         exit(1);
1189                 }
1190                 execvp(av[0], av);
1191                 perror(av[0]);
1192                 exit(1);
1193         }
1194         /* child */
1195         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1196
1197         if (setsid() == -1) {
1198                 error("setsid: %s", strerror(errno));
1199                 cleanup_exit(1);
1200         }
1201
1202         (void)chdir("/");
1203         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1204                 /* XXX might close listen socket */
1205                 (void)dup2(fd, STDIN_FILENO);
1206                 (void)dup2(fd, STDOUT_FILENO);
1207                 (void)dup2(fd, STDERR_FILENO);
1208                 if (fd > 2)
1209                         close(fd);
1210         }
1211
1212 #ifdef HAVE_SETRLIMIT
1213         /* deny core dumps, since memory contains unencrypted private keys */
1214         rlim.rlim_cur = rlim.rlim_max = 0;
1215         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1216                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1217                 cleanup_exit(1);
1218         }
1219 #endif
1220
1221 skip:
1222         new_socket(AUTH_SOCKET, sock);
1223         if (ac > 0) {
1224                 mysignal(SIGALRM, check_parent_exists);
1225                 alarm(10);
1226         }
1227         idtab_init();
1228         if (!d_flag)
1229                 signal(SIGINT, SIG_IGN);
1230         signal(SIGPIPE, SIG_IGN);
1231         signal(SIGHUP, cleanup_handler);
1232         signal(SIGTERM, cleanup_handler);
1233         nalloc = 0;
1234
1235         while (1) {
1236                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1237                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1238                         if (errno == EINTR)
1239                                 continue;
1240                         fatal("select: %s", strerror(errno));
1241                 }
1242                 after_select(readsetp, writesetp);
1243         }
1244         /* NOTREACHED */
1245 }