openssh/ssh-agent.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * The authentication agent program.
   6  *
   7  * As far as I am concerned, the code I have written for this software
   8  * can be used freely for any purpose.  Any derived versions of this
   9  * software must be clearly marked as such, and if the derived work is
  10  * incompatible with the protocol description in the RFC file, it must be
  11  * called by a name other than "ssh" or "Secure Shell".
  12  *
  13  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  14  *
  15  * Redistribution and use in source and binary forms, with or without
  16  * modification, are permitted provided that the following conditions
  17  * are met:
  18  * 1. Redistributions of source code must retain the above copyright
  19  *    notice, this list of conditions and the following disclaimer.
  20  * 2. Redistributions in binary form must reproduce the above copyright
  21  *    notice, this list of conditions and the following disclaimer in the
  22  *    documentation and/or other materials provided with the distribution.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  27  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  28  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  29  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  30  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  31  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  32  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  33  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 #include "includes.h"
  37 #include "openbsd-compat/sys-queue.h"
  38 RCSID("$OpenBSD: ssh-agent.c,v 1.124 2005/10/30 08:52:18 djm Exp $");
  39
  40 #include <openssl/evp.h>
  41 #include <openssl/md5.h>
  42
  43 #include "ssh.h"
  44 #include "rsa.h"
  45 #include "buffer.h"
  46 #include "bufaux.h"
  47 #include "xmalloc.h"
  48 #include "getput.h"
  49 #include "key.h"
  50 #include "authfd.h"
  51 #include "compat.h"
  52 #include "log.h"
  53 #include "pathnames.h"
  54 #include "misc.h"
  55
  56 #ifdef SMARTCARD
  57 #include "scard.h"
  58 #endif
  59
  60 #if defined(HAVE_SYS_PRCTL_H)
  61 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  62 #endif
  63
  64 typedef enum {
  65         AUTH_UNUSED,
  66         AUTH_SOCKET,
  67         AUTH_CONNECTION
  68 } sock_type;
  69
  70 typedef struct {
  71         int fd;
  72         sock_type type;
  73         Buffer input;
  74         Buffer output;
  75         Buffer request;
  76 } SocketEntry;
  77
  78 u_int sockets_alloc = 0;
  79 SocketEntry *sockets = NULL;
  80
  81 typedef struct identity {
  82         TAILQ_ENTRY(identity) next;
  83         Key *key;
  84         char *comment;
  85         u_int death;
  86         u_int confirm;
  87 } Identity;
  88
  89 typedef struct {
  90         int nentries;
  91         TAILQ_HEAD(idqueue, identity) idlist;
  92 } Idtab;
  93
  94 /* private key table, one per protocol version */
  95 Idtab idtable[3];
  96
  97 int max_fd = 0;
  98
  99 /* pid of shell == parent of agent */
 100 pid_t parent_pid = -1;
 101
 102 /* pathname and directory for AUTH_SOCKET */
 103 char socket_name[1024];
 104 char socket_dir[1024];
 105
 106 /* locking */
 107 int locked = 0;
 108 char *lock_passwd = NULL;
 109
 110 extern char *__progname;
 111
 112 /* Default lifetime (0 == forever) */
 113 static int lifetime = 0;
 114
 115 static void
 116 close_socket(SocketEntry *e)
 117 {
 118         close(e->fd);
 119         e->fd = -1;
 120         e->type = AUTH_UNUSED;
 121         buffer_free(&e->input);
 122         buffer_free(&e->output);
 123         buffer_free(&e->request);
 124 }
 125
 126 static void
 127 idtab_init(void)
 128 {
 129         int i;
 130
 131         for (i = 0; i <=2; i++) {
 132                 TAILQ_INIT(&idtable[i].idlist);
 133                 idtable[i].nentries = 0;
 134         }
 135 }
 136
 137 /* return private key table for requested protocol version */
 138 static Idtab *
 139 idtab_lookup(int version)
 140 {
 141         if (version < 1 || version > 2)
 142                 fatal("internal error, bad protocol version %d", version);
 143         return &idtable[version];
 144 }
 145
 146 static void
 147 free_identity(Identity *id)
 148 {
 149         key_free(id->key);
 150         xfree(id->comment);
 151         xfree(id);
 152 }
 153
 154 /* return matching private key for given public key */
 155 static Identity *
 156 lookup_identity(Key *key, int version)
 157 {
 158         Identity *id;
 159
 160         Idtab *tab = idtab_lookup(version);
 161         TAILQ_FOREACH(id, &tab->idlist, next) {
 162                 if (key_equal(key, id->key))
 163                         return (id);
 164         }
 165         return (NULL);
 166 }
 167
 168 /* Check confirmation of keysign request */
 169 static int
 170 confirm_key(Identity *id)
 171 {
 172         char *p;
 173         int ret = -1;
 174
 175         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 176         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 177             id->comment, p))
 178                 ret = 0;
 179         xfree(p);
 180
 181         return (ret);
 182 }
 183
 184 /* send list of supported public keys to 'client' */
 185 static void
 186 process_request_identities(SocketEntry *e, int version)
 187 {
 188         Idtab *tab = idtab_lookup(version);
 189         Identity *id;
 190         Buffer msg;
 191
 192         buffer_init(&msg);
 193         buffer_put_char(&msg, (version == 1) ?
 194             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 195         buffer_put_int(&msg, tab->nentries);
 196         TAILQ_FOREACH(id, &tab->idlist, next) {
 197                 if (id->key->type == KEY_RSA1) {
 198                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 199                         buffer_put_bignum(&msg, id->key->rsa->e);
 200                         buffer_put_bignum(&msg, id->key->rsa->n);
 201                 } else {
 202                         u_char *blob;
 203                         u_int blen;
 204                         key_to_blob(id->key, &blob, &blen);
 205                         buffer_put_string(&msg, blob, blen);
 206                         xfree(blob);
 207                 }
 208                 buffer_put_cstring(&msg, id->comment);
 209         }
 210         buffer_put_int(&e->output, buffer_len(&msg));
 211         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 212         buffer_free(&msg);
 213 }
 214
 215 /* ssh1 only */
 216 static void
 217 process_authentication_challenge1(SocketEntry *e)
 218 {
 219         u_char buf[32], mdbuf[16], session_id[16];
 220         u_int response_type;
 221         BIGNUM *challenge;
 222         Identity *id;
 223         int i, len;
 224         Buffer msg;
 225         MD5_CTX md;
 226         Key *key;
 227
 228         buffer_init(&msg);
 229         key = key_new(KEY_RSA1);
 230         if ((challenge = BN_new()) == NULL)
 231                 fatal("process_authentication_challenge1: BN_new failed");
 232
 233         (void) buffer_get_int(&e->request);                     /* ignored */
 234         buffer_get_bignum(&e->request, key->rsa->e);
 235         buffer_get_bignum(&e->request, key->rsa->n);
 236         buffer_get_bignum(&e->request, challenge);
 237
 238         /* Only protocol 1.1 is supported */
 239         if (buffer_len(&e->request) == 0)
 240                 goto failure;
 241         buffer_get(&e->request, session_id, 16);
 242         response_type = buffer_get_int(&e->request);
 243         if (response_type != 1)
 244                 goto failure;
 245
 246         id = lookup_identity(key, 1);
 247         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 248                 Key *private = id->key;
 249                 /* Decrypt the challenge using the private key. */
 250                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 251                         goto failure;
 252
 253                 /* The response is MD5 of decrypted challenge plus session id. */
 254                 len = BN_num_bytes(challenge);
 255                 if (len <= 0 || len > 32) {
 256                         logit("process_authentication_challenge: bad challenge length %d", len);
 257                         goto failure;
 258                 }
 259                 memset(buf, 0, 32);
 260                 BN_bn2bin(challenge, buf + 32 - len);
 261                 MD5_Init(&md);
 262                 MD5_Update(&md, buf, 32);
 263                 MD5_Update(&md, session_id, 16);
 264                 MD5_Final(mdbuf, &md);
 265
 266                 /* Send the response. */
 267                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 268                 for (i = 0; i < 16; i++)
 269                         buffer_put_char(&msg, mdbuf[i]);
 270                 goto send;
 271         }
 272
 273 failure:
 274         /* Unknown identity or protocol error.  Send failure. */
 275         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 276 send:
 277         buffer_put_int(&e->output, buffer_len(&msg));
 278         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 279         key_free(key);
 280         BN_clear_free(challenge);
 281         buffer_free(&msg);
 282 }
 283
 284 /* ssh2 only */
 285 static void
 286 process_sign_request2(SocketEntry *e)
 287 {
 288         u_char *blob, *data, *signature = NULL;
 289         u_int blen, dlen, slen = 0;
 290         extern int datafellows;
 291         int ok = -1, flags;
 292         Buffer msg;
 293         Key *key;
 294
 295         datafellows = 0;
 296
 297         blob = buffer_get_string(&e->request, &blen);
 298         data = buffer_get_string(&e->request, &dlen);
 299
 300         flags = buffer_get_int(&e->request);
 301         if (flags & SSH_AGENT_OLD_SIGNATURE)
 302                 datafellows = SSH_BUG_SIGBLOB;
 303
 304         key = key_from_blob(blob, blen);
 305         if (key != NULL) {
 306                 Identity *id = lookup_identity(key, 2);
 307                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 308                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 309         }
 310         key_free(key);
 311         buffer_init(&msg);
 312         if (ok == 0) {
 313                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 314                 buffer_put_string(&msg, signature, slen);
 315         } else {
 316                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 317         }
 318         buffer_put_int(&e->output, buffer_len(&msg));
 319         buffer_append(&e->output, buffer_ptr(&msg),
 320             buffer_len(&msg));
 321         buffer_free(&msg);
 322         xfree(data);
 323         xfree(blob);
 324         if (signature != NULL)
 325                 xfree(signature);
 326 }
 327
 328 /* shared */
 329 static void
 330 process_remove_identity(SocketEntry *e, int version)
 331 {
 332         u_int blen, bits;
 333         int success = 0;
 334         Key *key = NULL;
 335         u_char *blob;
 336
 337         switch (version) {
 338         case 1:
 339                 key = key_new(KEY_RSA1);
 340                 bits = buffer_get_int(&e->request);
 341                 buffer_get_bignum(&e->request, key->rsa->e);
 342                 buffer_get_bignum(&e->request, key->rsa->n);
 343
 344                 if (bits != key_size(key))
 345                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 346                             key_size(key), bits);
 347                 break;
 348         case 2:
 349                 blob = buffer_get_string(&e->request, &blen);
 350                 key = key_from_blob(blob, blen);
 351                 xfree(blob);
 352                 break;
 353         }
 354         if (key != NULL) {
 355                 Identity *id = lookup_identity(key, version);
 356                 if (id != NULL) {
 357                         /*
 358                          * We have this key.  Free the old key.  Since we
 359                          * don't want to leave empty slots in the middle of
 360                          * the array, we actually free the key there and move
 361                          * all the entries between the empty slot and the end
 362                          * of the array.
 363                          */
 364                         Idtab *tab = idtab_lookup(version);
 365                         if (tab->nentries < 1)
 366                                 fatal("process_remove_identity: "
 367                                     "internal error: tab->nentries %d",
 368                                     tab->nentries);
 369                         TAILQ_REMOVE(&tab->idlist, id, next);
 370                         free_identity(id);
 371                         tab->nentries--;
 372                         success = 1;
 373                 }
 374                 key_free(key);
 375         }
 376         buffer_put_int(&e->output, 1);
 377         buffer_put_char(&e->output,
 378             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 379 }
 380
 381 static void
 382 process_remove_all_identities(SocketEntry *e, int version)
 383 {
 384         Idtab *tab = idtab_lookup(version);
 385         Identity *id;
 386
 387         /* Loop over all identities and clear the keys. */
 388         for (id = TAILQ_FIRST(&tab->idlist); id;
 389             id = TAILQ_FIRST(&tab->idlist)) {
 390                 TAILQ_REMOVE(&tab->idlist, id, next);
 391                 free_identity(id);
 392         }
 393
 394         /* Mark that there are no identities. */
 395         tab->nentries = 0;
 396
 397         /* Send success. */
 398         buffer_put_int(&e->output, 1);
 399         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 400 }
 401
 402 static void
 403 reaper(void)
 404 {
 405         u_int now = time(NULL);
 406         Identity *id, *nxt;
 407         int version;
 408         Idtab *tab;
 409
 410         for (version = 1; version < 3; version++) {
 411                 tab = idtab_lookup(version);
 412                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 413                         nxt = TAILQ_NEXT(id, next);
 414                         if (id->death != 0 && now >= id->death) {
 415                                 TAILQ_REMOVE(&tab->idlist, id, next);
 416                                 free_identity(id);
 417                                 tab->nentries--;
 418                         }
 419                 }
 420         }
 421 }
 422
 423 static void
 424 process_add_identity(SocketEntry *e, int version)
 425 {
 426         Idtab *tab = idtab_lookup(version);
 427         int type, success = 0, death = 0, confirm = 0;
 428         char *type_name, *comment;
 429         Key *k = NULL;
 430
 431         switch (version) {
 432         case 1:
 433                 k = key_new_private(KEY_RSA1);
 434                 (void) buffer_get_int(&e->request);             /* ignored */
 435                 buffer_get_bignum(&e->request, k->rsa->n);
 436                 buffer_get_bignum(&e->request, k->rsa->e);
 437                 buffer_get_bignum(&e->request, k->rsa->d);
 438                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 439
 440                 /* SSH and SSL have p and q swapped */
 441                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 442                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 443
 444                 /* Generate additional parameters */
 445                 rsa_generate_additional_parameters(k->rsa);
 446                 break;
 447         case 2:
 448                 type_name = buffer_get_string(&e->request, NULL);
 449                 type = key_type_from_name(type_name);
 450                 xfree(type_name);
 451                 switch (type) {
 452                 case KEY_DSA:
 453                         k = key_new_private(type);
 454                         buffer_get_bignum2(&e->request, k->dsa->p);
 455                         buffer_get_bignum2(&e->request, k->dsa->q);
 456                         buffer_get_bignum2(&e->request, k->dsa->g);
 457                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 458                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 459                         break;
 460                 case KEY_RSA:
 461                         k = key_new_private(type);
 462                         buffer_get_bignum2(&e->request, k->rsa->n);
 463                         buffer_get_bignum2(&e->request, k->rsa->e);
 464                         buffer_get_bignum2(&e->request, k->rsa->d);
 465                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 466                         buffer_get_bignum2(&e->request, k->rsa->p);
 467                         buffer_get_bignum2(&e->request, k->rsa->q);
 468
 469                         /* Generate additional parameters */
 470                         rsa_generate_additional_parameters(k->rsa);
 471                         break;
 472                 default:
 473                         buffer_clear(&e->request);
 474                         goto send;
 475                 }
 476                 break;
 477         }
 478         /* enable blinding */
 479         switch (k->type) {
 480         case KEY_RSA:
 481         case KEY_RSA1:
 482                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 483                         error("process_add_identity: RSA_blinding_on failed");
 484                         key_free(k);
 485                         goto send;
 486                 }
 487                 break;
 488         }
 489         comment = buffer_get_string(&e->request, NULL);
 490         if (k == NULL) {
 491                 xfree(comment);
 492                 goto send;
 493         }
 494         success = 1;
 495         while (buffer_len(&e->request)) {
 496                 switch (buffer_get_char(&e->request)) {
 497                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 498                         death = time(NULL) + buffer_get_int(&e->request);
 499                         break;
 500                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 501                         confirm = 1;
 502                         break;
 503                 default:
 504                         break;
 505                 }
 506         }
 507         if (lifetime && !death)
 508                 death = time(NULL) + lifetime;
 509         if (lookup_identity(k, version) == NULL) {
 510                 Identity *id = xmalloc(sizeof(Identity));
 511                 id->key = k;
 512                 id->comment = comment;
 513                 id->death = death;
 514                 id->confirm = confirm;
 515                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 516                 /* Increment the number of identities. */
 517                 tab->nentries++;
 518         } else {
 519                 key_free(k);
 520                 xfree(comment);
 521         }
 522 send:
 523         buffer_put_int(&e->output, 1);
 524         buffer_put_char(&e->output,
 525             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 526 }
 527
 528 /* XXX todo: encrypt sensitive data with passphrase */
 529 static void
 530 process_lock_agent(SocketEntry *e, int lock)
 531 {
 532         int success = 0;
 533         char *passwd;
 534
 535         passwd = buffer_get_string(&e->request, NULL);
 536         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 537                 locked = 0;
 538                 memset(lock_passwd, 0, strlen(lock_passwd));
 539                 xfree(lock_passwd);
 540                 lock_passwd = NULL;
 541                 success = 1;
 542         } else if (!locked && lock) {
 543                 locked = 1;
 544                 lock_passwd = xstrdup(passwd);
 545                 success = 1;
 546         }
 547         memset(passwd, 0, strlen(passwd));
 548         xfree(passwd);
 549
 550         buffer_put_int(&e->output, 1);
 551         buffer_put_char(&e->output,
 552             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 553 }
 554
 555 static void
 556 no_identities(SocketEntry *e, u_int type)
 557 {
 558         Buffer msg;
 559
 560         buffer_init(&msg);
 561         buffer_put_char(&msg,
 562             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 563             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 564         buffer_put_int(&msg, 0);
 565         buffer_put_int(&e->output, buffer_len(&msg));
 566         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 567         buffer_free(&msg);
 568 }
 569
 570 #ifdef SMARTCARD
 571 static void
 572 process_add_smartcard_key (SocketEntry *e)
 573 {
 574         char *sc_reader_id = NULL, *pin;
 575         int i, version, success = 0, death = 0, confirm = 0;
 576         Key **keys, *k;
 577         Identity *id;
 578         Idtab *tab;
 579
 580         sc_reader_id = buffer_get_string(&e->request, NULL);
 581         pin = buffer_get_string(&e->request, NULL);
 582
 583         while (buffer_len(&e->request)) {
 584                 switch (buffer_get_char(&e->request)) {
 585                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 586                         death = time(NULL) + buffer_get_int(&e->request);
 587                         break;
 588                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 589                         confirm = 1;
 590                         break;
 591                 default:
 592                         break;
 593                 }
 594         }
 595         if (lifetime && !death)
 596                 death = time(NULL) + lifetime;
 597
 598         keys = sc_get_keys(sc_reader_id, pin);
 599         xfree(sc_reader_id);
 600         xfree(pin);
 601
 602         if (keys == NULL || keys[0] == NULL) {
 603                 error("sc_get_keys failed");
 604                 goto send;
 605         }
 606         for (i = 0; keys[i] != NULL; i++) {
 607                 k = keys[i];
 608                 version = k->type == KEY_RSA1 ? 1 : 2;
 609                 tab = idtab_lookup(version);
 610                 if (lookup_identity(k, version) == NULL) {
 611                         id = xmalloc(sizeof(Identity));
 612                         id->key = k;
 613                         id->comment = sc_get_key_label(k);
 614                         id->death = death;
 615                         id->confirm = confirm;
 616                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 617                         tab->nentries++;
 618                         success = 1;
 619                 } else {
 620                         key_free(k);
 621                 }
 622                 keys[i] = NULL;
 623         }
 624         xfree(keys);
 625 send:
 626         buffer_put_int(&e->output, 1);
 627         buffer_put_char(&e->output,
 628             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 629 }
 630
 631 static void
 632 process_remove_smartcard_key(SocketEntry *e)
 633 {
 634         char *sc_reader_id = NULL, *pin;
 635         int i, version, success = 0;
 636         Key **keys, *k = NULL;
 637         Identity *id;
 638         Idtab *tab;
 639
 640         sc_reader_id = buffer_get_string(&e->request, NULL);
 641         pin = buffer_get_string(&e->request, NULL);
 642         keys = sc_get_keys(sc_reader_id, pin);
 643         xfree(sc_reader_id);
 644         xfree(pin);
 645
 646         if (keys == NULL || keys[0] == NULL) {
 647                 error("sc_get_keys failed");
 648                 goto send;
 649         }
 650         for (i = 0; keys[i] != NULL; i++) {
 651                 k = keys[i];
 652                 version = k->type == KEY_RSA1 ? 1 : 2;
 653                 if ((id = lookup_identity(k, version)) != NULL) {
 654                         tab = idtab_lookup(version);
 655                         TAILQ_REMOVE(&tab->idlist, id, next);
 656                         tab->nentries--;
 657                         free_identity(id);
 658                         success = 1;
 659                 }
 660                 key_free(k);
 661                 keys[i] = NULL;
 662         }
 663         xfree(keys);
 664 send:
 665         buffer_put_int(&e->output, 1);
 666         buffer_put_char(&e->output,
 667             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 668 }
 669 #endif /* SMARTCARD */
 670
 671 /* dispatch incoming messages */
 672
 673 static void
 674 process_message(SocketEntry *e)
 675 {
 676         u_int msg_len, type;
 677         u_char *cp;
 678
 679         /* kill dead keys */
 680         reaper();
 681
 682         if (buffer_len(&e->input) < 5)
 683                 return;         /* Incomplete message. */
 684         cp = buffer_ptr(&e->input);
 685         msg_len = GET_32BIT(cp);
 686         if (msg_len > 256 * 1024) {
 687                 close_socket(e);
 688                 return;
 689         }
 690         if (buffer_len(&e->input) < msg_len + 4)
 691                 return;
 692
 693         /* move the current input to e->request */
 694         buffer_consume(&e->input, 4);
 695         buffer_clear(&e->request);
 696         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 697         buffer_consume(&e->input, msg_len);
 698         type = buffer_get_char(&e->request);
 699
 700         /* check wheter agent is locked */
 701         if (locked && type != SSH_AGENTC_UNLOCK) {
 702                 buffer_clear(&e->request);
 703                 switch (type) {
 704                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 705                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 706                         /* send empty lists */
 707                         no_identities(e, type);
 708                         break;
 709                 default:
 710                         /* send a fail message for all other request types */
 711                         buffer_put_int(&e->output, 1);
 712                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 713                 }
 714                 return;
 715         }
 716
 717         debug("type %d", type);
 718         switch (type) {
 719         case SSH_AGENTC_LOCK:
 720         case SSH_AGENTC_UNLOCK:
 721                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 722                 break;
 723         /* ssh1 */
 724         case SSH_AGENTC_RSA_CHALLENGE:
 725                 process_authentication_challenge1(e);
 726                 break;
 727         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 728                 process_request_identities(e, 1);
 729                 break;
 730         case SSH_AGENTC_ADD_RSA_IDENTITY:
 731         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 732                 process_add_identity(e, 1);
 733                 break;
 734         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 735                 process_remove_identity(e, 1);
 736                 break;
 737         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 738                 process_remove_all_identities(e, 1);
 739                 break;
 740         /* ssh2 */
 741         case SSH2_AGENTC_SIGN_REQUEST:
 742                 process_sign_request2(e);
 743                 break;
 744         case SSH2_AGENTC_REQUEST_IDENTITIES:
 745                 process_request_identities(e, 2);
 746                 break;
 747         case SSH2_AGENTC_ADD_IDENTITY:
 748         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 749                 process_add_identity(e, 2);
 750                 break;
 751         case SSH2_AGENTC_REMOVE_IDENTITY:
 752                 process_remove_identity(e, 2);
 753                 break;
 754         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 755                 process_remove_all_identities(e, 2);
 756                 break;
 757 #ifdef SMARTCARD
 758         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 759         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 760                 process_add_smartcard_key(e);
 761                 break;
 762         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 763                 process_remove_smartcard_key(e);
 764                 break;
 765 #endif /* SMARTCARD */
 766         default:
 767                 /* Unknown message.  Respond with failure. */
 768                 error("Unknown message %d", type);
 769                 buffer_clear(&e->request);
 770                 buffer_put_int(&e->output, 1);
 771                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 772                 break;
 773         }
 774 }
 775
 776 static void
 777 new_socket(sock_type type, int fd)
 778 {
 779         u_int i, old_alloc, new_alloc;
 780
 781         set_nonblock(fd);
 782
 783         if (fd > max_fd)
 784                 max_fd = fd;
 785
 786         for (i = 0; i < sockets_alloc; i++)
 787                 if (sockets[i].type == AUTH_UNUSED) {
 788                         sockets[i].fd = fd;
 789                         buffer_init(&sockets[i].input);
 790                         buffer_init(&sockets[i].output);
 791                         buffer_init(&sockets[i].request);
 792                         sockets[i].type = type;
 793                         return;
 794                 }
 795         old_alloc = sockets_alloc;
 796         new_alloc = sockets_alloc + 10;
 797         if (sockets)
 798                 sockets = xrealloc(sockets, new_alloc * sizeof(sockets[0]));
 799         else
 800                 sockets = xmalloc(new_alloc * sizeof(sockets[0]));
 801         for (i = old_alloc; i < new_alloc; i++)
 802                 sockets[i].type = AUTH_UNUSED;
 803         sockets_alloc = new_alloc;
 804         sockets[old_alloc].fd = fd;
 805         buffer_init(&sockets[old_alloc].input);
 806         buffer_init(&sockets[old_alloc].output);
 807         buffer_init(&sockets[old_alloc].request);
 808         sockets[old_alloc].type = type;
 809 }
 810
 811 static int
 812 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
 813 {
 814         u_int i, sz;
 815         int n = 0;
 816
 817         for (i = 0; i < sockets_alloc; i++) {
 818                 switch (sockets[i].type) {
 819                 case AUTH_SOCKET:
 820                 case AUTH_CONNECTION:
 821                         n = MAX(n, sockets[i].fd);
 822                         break;
 823                 case AUTH_UNUSED:
 824                         break;
 825                 default:
 826                         fatal("Unknown socket type %d", sockets[i].type);
 827                         break;
 828                 }
 829         }
 830
 831         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 832         if (*fdrp == NULL || sz > *nallocp) {
 833                 if (*fdrp)
 834                         xfree(*fdrp);
 835                 if (*fdwp)
 836                         xfree(*fdwp);
 837                 *fdrp = xmalloc(sz);
 838                 *fdwp = xmalloc(sz);
 839                 *nallocp = sz;
 840         }
 841         if (n < *fdl)
 842                 debug("XXX shrink: %d < %d", n, *fdl);
 843         *fdl = n;
 844         memset(*fdrp, 0, sz);
 845         memset(*fdwp, 0, sz);
 846
 847         for (i = 0; i < sockets_alloc; i++) {
 848                 switch (sockets[i].type) {
 849                 case AUTH_SOCKET:
 850                 case AUTH_CONNECTION:
 851                         FD_SET(sockets[i].fd, *fdrp);
 852                         if (buffer_len(&sockets[i].output) > 0)
 853                                 FD_SET(sockets[i].fd, *fdwp);
 854                         break;
 855                 default:
 856                         break;
 857                 }
 858         }
 859         return (1);
 860 }
 861
 862 static void
 863 after_select(fd_set *readset, fd_set *writeset)
 864 {
 865         struct sockaddr_un sunaddr;
 866         socklen_t slen;
 867         char buf[1024];
 868         int len, sock;
 869         u_int i;
 870         uid_t euid;
 871         gid_t egid;
 872
 873         for (i = 0; i < sockets_alloc; i++)
 874                 switch (sockets[i].type) {
 875                 case AUTH_UNUSED:
 876                         break;
 877                 case AUTH_SOCKET:
 878                         if (FD_ISSET(sockets[i].fd, readset)) {
 879                                 slen = sizeof(sunaddr);
 880                                 sock = accept(sockets[i].fd,
 881                                     (struct sockaddr *) &sunaddr, &slen);
 882                                 if (sock < 0) {
 883                                         error("accept from AUTH_SOCKET: %s",
 884                                             strerror(errno));
 885                                         break;
 886                                 }
 887                                 if (getpeereid(sock, &euid, &egid) < 0) {
 888                                         error("getpeereid %d failed: %s",
 889                                             sock, strerror(errno));
 890                                         close(sock);
 891                                         break;
 892                                 }
 893                                 if ((euid != 0) && (getuid() != euid)) {
 894                                         error("uid mismatch: "
 895                                             "peer euid %u != uid %u",
 896                                             (u_int) euid, (u_int) getuid());
 897                                         close(sock);
 898                                         break;
 899                                 }
 900                                 new_socket(AUTH_CONNECTION, sock);
 901                         }
 902                         break;
 903                 case AUTH_CONNECTION:
 904                         if (buffer_len(&sockets[i].output) > 0 &&
 905                             FD_ISSET(sockets[i].fd, writeset)) {
 906                                 do {
 907                                         len = write(sockets[i].fd,
 908                                             buffer_ptr(&sockets[i].output),
 909                                             buffer_len(&sockets[i].output));
 910                                         if (len == -1 && (errno == EAGAIN ||
 911                                             errno == EINTR))
 912                                                 continue;
 913                                         break;
 914                                 } while (1);
 915                                 if (len <= 0) {
 916                                         close_socket(&sockets[i]);
 917                                         break;
 918                                 }
 919                                 buffer_consume(&sockets[i].output, len);
 920                         }
 921                         if (FD_ISSET(sockets[i].fd, readset)) {
 922                                 do {
 923                                         len = read(sockets[i].fd, buf, sizeof(buf));
 924                                         if (len == -1 && (errno == EAGAIN ||
 925                                             errno == EINTR))
 926                                                 continue;
 927                                         break;
 928                                 } while (1);
 929                                 if (len <= 0) {
 930                                         close_socket(&sockets[i]);
 931                                         break;
 932                                 }
 933                                 buffer_append(&sockets[i].input, buf, len);
 934                                 process_message(&sockets[i]);
 935                         }
 936                         break;
 937                 default:
 938                         fatal("Unknown type %d", sockets[i].type);
 939                 }
 940 }
 941
 942 static void
 943 cleanup_socket(void)
 944 {
 945         if (socket_name[0])
 946                 unlink(socket_name);
 947         if (socket_dir[0])
 948                 rmdir(socket_dir);
 949 }
 950
 951 void
 952 cleanup_exit(int i)
 953 {
 954         cleanup_socket();
 955         _exit(i);
 956 }
 957
 958 static void
 959 cleanup_handler(int sig)
 960 {
 961         cleanup_socket();
 962         _exit(2);
 963 }
 964
 965 static void
 966 check_parent_exists(int sig)
 967 {
 968         int save_errno = errno;
 969
 970         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 971                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 972                 cleanup_handler(sig); /* safe */
 973         }
 974         mysignal(SIGALRM, check_parent_exists);
 975         alarm(10);
 976         errno = save_errno;
 977 }
 978
 979 static void
 980 usage(void)
 981 {
 982         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 983             __progname);
 984         fprintf(stderr, "Options:\n");
 985         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 986         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 987         fprintf(stderr, "  -k          Kill the current agent.\n");
 988         fprintf(stderr, "  -d          Debug mode.\n");
 989         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 990         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
 991         exit(1);
 992 }
 993
 994 int
 995 main(int ac, char **av)
 996 {
 997         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
 998         int sock, fd,  ch;
 999         u_int nalloc;
1000         char *shell, *format, *pidstr, *agentsocket = NULL;
1001         fd_set *readsetp = NULL, *writesetp = NULL;
1002         struct sockaddr_un sunaddr;
1003 #ifdef HAVE_SETRLIMIT
1004         struct rlimit rlim;
1005 #endif
1006         int prev_mask;
1007         extern int optind;
1008         extern char *optarg;
1009         pid_t pid;
1010         char pidstrbuf[1 + 3 * sizeof pid];
1011
1012         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1013         sanitise_stdfd();
1014
1015         /* drop */
1016         setegid(getgid());
1017         setgid(getgid());
1018
1019 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1020         /* Disable ptrace on Linux without sgid bit */
1021         prctl(PR_SET_DUMPABLE, 0);
1022 #endif
1023
1024         SSLeay_add_all_algorithms();
1025
1026         __progname = ssh_get_progname(av[0]);
1027         init_pathnames();
1028         init_rng();
1029         seed_rng();
1030
1031         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1032                 switch (ch) {
1033                 case 'c':
1034                         if (s_flag)
1035                                 usage();
1036                         c_flag++;
1037                         break;
1038                 case 'k':
1039                         k_flag++;
1040                         break;
1041                 case 's':
1042                         if (c_flag)
1043                                 usage();
1044                         s_flag++;
1045                         break;
1046                 case 'd':
1047                         if (d_flag)
1048                                 usage();
1049                         d_flag++;
1050                         break;
1051                 case 'a':
1052                         agentsocket = optarg;
1053                         break;
1054                 case 't':
1055                         if ((lifetime = convtime(optarg)) == -1) {
1056                                 fprintf(stderr, "Invalid lifetime\n");
1057                                 usage();
1058                         }
1059                         break;
1060                 default:
1061                         usage();
1062                 }
1063         }
1064         ac -= optind;
1065         av += optind;
1066
1067         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1068                 usage();
1069
1070         if (ac == 0 && !c_flag && !s_flag) {
1071                 shell = getenv("SHELL");
1072                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1073                         c_flag = 1;
1074         }
1075         if (k_flag) {
1076                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1077                 if (pidstr == NULL) {
1078                         fprintf(stderr, "%s not set, cannot kill agent\n",
1079                             SSH_AGENTPID_ENV_NAME);
1080                         exit(1);
1081                 }
1082                 pid = atoi(pidstr);
1083                 if (pid < 1) {
1084                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
1085                             SSH_AGENTPID_ENV_NAME, pidstr);
1086                         exit(1);
1087                 }
1088                 if (kill(pid, SIGTERM) == -1) {
1089                         perror("kill");
1090                         exit(1);
1091                 }
1092                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1093                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1094                 printf(format, SSH_AGENTPID_ENV_NAME);
1095                 printf("echo Agent pid %ld killed;\n", (long)pid);
1096                 exit(0);
1097         }
1098         parent_pid = getpid();
1099
1100         if (agentsocket == NULL) {
1101                 /* Create private directory for agent socket */
1102                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1103                 if (mkdtemp(socket_dir) == NULL) {
1104                         perror("mkdtemp: private socket dir");
1105                         exit(1);
1106                 }
1107                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1108                     (long)parent_pid);
1109         } else {
1110                 /* Try to use specified agent socket */
1111                 socket_dir[0] = '\0';
1112                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1113         }
1114
1115         /*
1116          * Create socket early so it will exist before command gets run from
1117          * the parent.
1118          */
1119         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1120         if (sock < 0) {
1121                 perror("socket");
1122                 *socket_name = '\0'; /* Don't unlink any existing file */
1123                 cleanup_exit(1);
1124         }
1125         memset(&sunaddr, 0, sizeof(sunaddr));
1126         sunaddr.sun_family = AF_UNIX;
1127         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1128         prev_mask = umask(0177);
1129         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1130                 perror("bind");
1131                 *socket_name = '\0'; /* Don't unlink any existing file */
1132                 umask(prev_mask);
1133                 cleanup_exit(1);
1134         }
1135         umask(prev_mask);
1136         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1137                 perror("listen");
1138                 cleanup_exit(1);
1139         }
1140
1141         /*
1142          * Fork, and have the parent execute the command, if any, or present
1143          * the socket data.  The child continues as the authentication agent.
1144          */
1145         if (d_flag) {
1146                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1147                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1148                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1149                     SSH_AUTHSOCKET_ENV_NAME);
1150                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1151                 goto skip;
1152         }
1153         pid = fork();
1154         if (pid == -1) {
1155                 perror("fork");
1156                 cleanup_exit(1);
1157         }
1158         if (pid != 0) {         /* Parent - execute the given command. */
1159                 close(sock);
1160                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1161                 if (ac == 0) {
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(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1166                             SSH_AGENTPID_ENV_NAME);
1167                         printf("echo Agent pid %ld;\n", (long)pid);
1168                         exit(0);
1169                 }
1170                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1171                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1172                         perror("setenv");
1173                         exit(1);
1174                 }
1175                 execvp(av[0], av);
1176                 perror(av[0]);
1177                 exit(1);
1178         }
1179         /* child */
1180         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1181
1182         if (setsid() == -1) {
1183                 error("setsid: %s", strerror(errno));
1184                 cleanup_exit(1);
1185         }
1186
1187         (void)chdir("/");
1188         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1189                 /* XXX might close listen socket */
1190                 (void)dup2(fd, STDIN_FILENO);
1191                 (void)dup2(fd, STDOUT_FILENO);
1192                 (void)dup2(fd, STDERR_FILENO);
1193                 if (fd > 2)
1194                         close(fd);
1195         }
1196
1197 #ifdef HAVE_SETRLIMIT
1198         /* deny core dumps, since memory contains unencrypted private keys */
1199         rlim.rlim_cur = rlim.rlim_max = 0;
1200         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1201                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1202                 cleanup_exit(1);
1203         }
1204 #endif
1205
1206 skip:
1207         new_socket(AUTH_SOCKET, sock);
1208         if (ac > 0) {
1209                 mysignal(SIGALRM, check_parent_exists);
1210                 alarm(10);
1211         }
1212         idtab_init();
1213         if (!d_flag)
1214                 signal(SIGINT, SIG_IGN);
1215         signal(SIGPIPE, SIG_IGN);
1216         signal(SIGHUP, cleanup_handler);
1217         signal(SIGTERM, cleanup_handler);
1218         nalloc = 0;
1219
1220         while (1) {
1221                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1222                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1223                         if (errno == EINTR)
1224                                 continue;
1225                         fatal("select: %s", strerror(errno));
1226                 }
1227                 after_select(readsetp, writesetp);
1228         }
1229         /* NOTREACHED */
1230 }