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 1.108 2003/03/13 11:44:50 markus 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 "readpass.h"
  54 #include "misc.h"
  55
  56 #ifdef SMARTCARD
  57 #include "scard.h"
  58 #endif
  59
  60 typedef enum {
  61         AUTH_UNUSED,
  62         AUTH_SOCKET,
  63         AUTH_CONNECTION
  64 } sock_type;
  65
  66 typedef struct {
  67         int fd;
  68         sock_type type;
  69         Buffer input;
  70         Buffer output;
  71         Buffer request;
  72 } SocketEntry;
  73
  74 u_int sockets_alloc = 0;
  75 SocketEntry *sockets = NULL;
  76
  77 typedef struct identity {
  78         TAILQ_ENTRY(identity) next;
  79         Key *key;
  80         char *comment;
  81         u_int death;
  82         u_int confirm;
  83 } Identity;
  84
  85 typedef struct {
  86         int nentries;
  87         TAILQ_HEAD(idqueue, identity) idlist;
  88 } Idtab;
  89
  90 /* private key table, one per protocol version */
  91 Idtab idtable[3];
  92
  93 int max_fd = 0;
  94
  95 /* pid of shell == parent of agent */
  96 pid_t parent_pid = -1;
  97
  98 /* pathname and directory for AUTH_SOCKET */
  99 char socket_name[1024];
 100 char socket_dir[1024];
 101
 102 /* locking */
 103 int locked = 0;
 104 char *lock_passwd = NULL;
 105
 106 #ifdef HAVE___PROGNAME
 107 extern char *__progname;
 108 #else
 109 char *__progname;
 110 #endif
 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, prompt[1024];
 173         int ret = -1;
 174
 175         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 176         snprintf(prompt, sizeof(prompt), "Allow use of key %s?\n"
 177             "Key fingerprint %s.", id->comment, p);
 178         xfree(p);
 179         p = read_passphrase(prompt, RP_ALLOW_EOF);
 180         if (p != NULL) {
 181                 /*
 182                  * Accept empty responses and responses consisting
 183                  * of the word "yes" as affirmative.
 184                  */
 185                 if (*p == '\0' || *p == '\n' || strcasecmp(p, "yes") == 0)
 186                         ret = 0;
 187                 xfree(p);
 188         }
 189         return (ret);
 190 }
 191
 192 /* send list of supported public keys to 'client' */
 193 static void
 194 process_request_identities(SocketEntry *e, int version)
 195 {
 196         Idtab *tab = idtab_lookup(version);
 197         Identity *id;
 198         Buffer msg;
 199
 200         buffer_init(&msg);
 201         buffer_put_char(&msg, (version == 1) ?
 202             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 203         buffer_put_int(&msg, tab->nentries);
 204         TAILQ_FOREACH(id, &tab->idlist, next) {
 205                 if (id->key->type == KEY_RSA1) {
 206                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 207                         buffer_put_bignum(&msg, id->key->rsa->e);
 208                         buffer_put_bignum(&msg, id->key->rsa->n);
 209                 } else {
 210                         u_char *blob;
 211                         u_int blen;
 212                         key_to_blob(id->key, &blob, &blen);
 213                         buffer_put_string(&msg, blob, blen);
 214                         xfree(blob);
 215                 }
 216                 buffer_put_cstring(&msg, id->comment);
 217         }
 218         buffer_put_int(&e->output, buffer_len(&msg));
 219         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 220         buffer_free(&msg);
 221 }
 222
 223 /* ssh1 only */
 224 static void
 225 process_authentication_challenge1(SocketEntry *e)
 226 {
 227         u_char buf[32], mdbuf[16], session_id[16];
 228         u_int response_type;
 229         BIGNUM *challenge;
 230         Identity *id;
 231         int i, len;
 232         Buffer msg;
 233         MD5_CTX md;
 234         Key *key;
 235
 236         buffer_init(&msg);
 237         key = key_new(KEY_RSA1);
 238         if ((challenge = BN_new()) == NULL)
 239                 fatal("process_authentication_challenge1: BN_new failed");
 240
 241         (void) buffer_get_int(&e->request);                     /* ignored */
 242         buffer_get_bignum(&e->request, key->rsa->e);
 243         buffer_get_bignum(&e->request, key->rsa->n);
 244         buffer_get_bignum(&e->request, challenge);
 245
 246         /* Only protocol 1.1 is supported */
 247         if (buffer_len(&e->request) == 0)
 248                 goto failure;
 249         buffer_get(&e->request, session_id, 16);
 250         response_type = buffer_get_int(&e->request);
 251         if (response_type != 1)
 252                 goto failure;
 253
 254         id = lookup_identity(key, 1);
 255         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 256                 Key *private = id->key;
 257                 /* Decrypt the challenge using the private key. */
 258                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 259                         goto failure;
 260
 261                 /* The response is MD5 of decrypted challenge plus session id. */
 262                 len = BN_num_bytes(challenge);
 263                 if (len <= 0 || len > 32) {
 264                         log("process_authentication_challenge: bad challenge length %d", len);
 265                         goto failure;
 266                 }
 267                 memset(buf, 0, 32);
 268                 BN_bn2bin(challenge, buf + 32 - len);
 269                 MD5_Init(&md);
 270                 MD5_Update(&md, buf, 32);
 271                 MD5_Update(&md, session_id, 16);
 272                 MD5_Final(mdbuf, &md);
 273
 274                 /* Send the response. */
 275                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 276                 for (i = 0; i < 16; i++)
 277                         buffer_put_char(&msg, mdbuf[i]);
 278                 goto send;
 279         }
 280
 281 failure:
 282         /* Unknown identity or protocol error.  Send failure. */
 283         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 284 send:
 285         buffer_put_int(&e->output, buffer_len(&msg));
 286         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 287         key_free(key);
 288         BN_clear_free(challenge);
 289         buffer_free(&msg);
 290 }
 291
 292 /* ssh2 only */
 293 static void
 294 process_sign_request2(SocketEntry *e)
 295 {
 296         u_char *blob, *data, *signature = NULL;
 297         u_int blen, dlen, slen = 0;
 298         extern int datafellows;
 299         int ok = -1, flags;
 300         Buffer msg;
 301         Key *key;
 302
 303         datafellows = 0;
 304
 305         blob = buffer_get_string(&e->request, &blen);
 306         data = buffer_get_string(&e->request, &dlen);
 307
 308         flags = buffer_get_int(&e->request);
 309         if (flags & SSH_AGENT_OLD_SIGNATURE)
 310                 datafellows = SSH_BUG_SIGBLOB;
 311
 312         key = key_from_blob(blob, blen);
 313         if (key != NULL) {
 314                 Identity *id = lookup_identity(key, 2);
 315                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 316                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 317         }
 318         key_free(key);
 319         buffer_init(&msg);
 320         if (ok == 0) {
 321                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 322                 buffer_put_string(&msg, signature, slen);
 323         } else {
 324                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 325         }
 326         buffer_put_int(&e->output, buffer_len(&msg));
 327         buffer_append(&e->output, buffer_ptr(&msg),
 328             buffer_len(&msg));
 329         buffer_free(&msg);
 330         xfree(data);
 331         xfree(blob);
 332         if (signature != NULL)
 333                 xfree(signature);
 334 }
 335
 336 /* shared */
 337 static void
 338 process_remove_identity(SocketEntry *e, int version)
 339 {
 340         u_int blen, bits;
 341         int success = 0;
 342         Key *key = NULL;
 343         u_char *blob;
 344
 345         switch (version) {
 346         case 1:
 347                 key = key_new(KEY_RSA1);
 348                 bits = buffer_get_int(&e->request);
 349                 buffer_get_bignum(&e->request, key->rsa->e);
 350                 buffer_get_bignum(&e->request, key->rsa->n);
 351
 352                 if (bits != key_size(key))
 353                         log("Warning: identity keysize mismatch: actual %u, announced %u",
 354                             key_size(key), bits);
 355                 break;
 356         case 2:
 357                 blob = buffer_get_string(&e->request, &blen);
 358                 key = key_from_blob(blob, blen);
 359                 xfree(blob);
 360                 break;
 361         }
 362         if (key != NULL) {
 363                 Identity *id = lookup_identity(key, version);
 364                 if (id != NULL) {
 365                         /*
 366                          * We have this key.  Free the old key.  Since we
 367                          * don\'t want to leave empty slots in the middle of
 368                          * the array, we actually free the key there and move
 369                          * all the entries between the empty slot and the end
 370                          * of the array.
 371                          */
 372                         Idtab *tab = idtab_lookup(version);
 373                         if (tab->nentries < 1)
 374                                 fatal("process_remove_identity: "
 375                                     "internal error: tab->nentries %d",
 376                                     tab->nentries);
 377                         TAILQ_REMOVE(&tab->idlist, id, next);
 378                         free_identity(id);
 379                         tab->nentries--;
 380                         success = 1;
 381                 }
 382                 key_free(key);
 383         }
 384         buffer_put_int(&e->output, 1);
 385         buffer_put_char(&e->output,
 386             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 387 }
 388
 389 static void
 390 process_remove_all_identities(SocketEntry *e, int version)
 391 {
 392         Idtab *tab = idtab_lookup(version);
 393         Identity *id;
 394
 395         /* Loop over all identities and clear the keys. */
 396         for (id = TAILQ_FIRST(&tab->idlist); id;
 397             id = TAILQ_FIRST(&tab->idlist)) {
 398                 TAILQ_REMOVE(&tab->idlist, id, next);
 399                 free_identity(id);
 400         }
 401
 402         /* Mark that there are no identities. */
 403         tab->nentries = 0;
 404
 405         /* Send success. */
 406         buffer_put_int(&e->output, 1);
 407         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 408 }
 409
 410 static void
 411 reaper(void)
 412 {
 413         u_int now = time(NULL);
 414         Identity *id, *nxt;
 415         int version;
 416         Idtab *tab;
 417
 418         for (version = 1; version < 3; version++) {
 419                 tab = idtab_lookup(version);
 420                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 421                         nxt = TAILQ_NEXT(id, next);
 422                         if (id->death != 0 && now >= id->death) {
 423                                 TAILQ_REMOVE(&tab->idlist, id, next);
 424                                 free_identity(id);
 425                                 tab->nentries--;
 426                         }
 427                 }
 428         }
 429 }
 430
 431 static void
 432 process_add_identity(SocketEntry *e, int version)
 433 {
 434         Idtab *tab = idtab_lookup(version);
 435         int type, success = 0, death = 0, confirm = 0;
 436         char *type_name, *comment;
 437         Key *k = NULL;
 438
 439         switch (version) {
 440         case 1:
 441                 k = key_new_private(KEY_RSA1);
 442                 (void) buffer_get_int(&e->request);             /* ignored */
 443                 buffer_get_bignum(&e->request, k->rsa->n);
 444                 buffer_get_bignum(&e->request, k->rsa->e);
 445                 buffer_get_bignum(&e->request, k->rsa->d);
 446                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 447
 448                 /* SSH and SSL have p and q swapped */
 449                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 450                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 451
 452                 /* Generate additional parameters */
 453                 rsa_generate_additional_parameters(k->rsa);
 454                 break;
 455         case 2:
 456                 type_name = buffer_get_string(&e->request, NULL);
 457                 type = key_type_from_name(type_name);
 458                 xfree(type_name);
 459                 switch (type) {
 460                 case KEY_DSA:
 461                         k = key_new_private(type);
 462                         buffer_get_bignum2(&e->request, k->dsa->p);
 463                         buffer_get_bignum2(&e->request, k->dsa->q);
 464                         buffer_get_bignum2(&e->request, k->dsa->g);
 465                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 466                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 467                         break;
 468                 case KEY_RSA:
 469                         k = key_new_private(type);
 470                         buffer_get_bignum2(&e->request, k->rsa->n);
 471                         buffer_get_bignum2(&e->request, k->rsa->e);
 472                         buffer_get_bignum2(&e->request, k->rsa->d);
 473                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 474                         buffer_get_bignum2(&e->request, k->rsa->p);
 475                         buffer_get_bignum2(&e->request, k->rsa->q);
 476
 477                         /* Generate additional parameters */
 478                         rsa_generate_additional_parameters(k->rsa);
 479                         break;
 480                 default:
 481                         buffer_clear(&e->request);
 482                         goto send;
 483                 }
 484                 break;
 485         }
 486         /* enable blinding */
 487         switch (k->type) {
 488         case KEY_RSA:
 489         case KEY_RSA1:
 490                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 491                         error("process_add_identity: RSA_blinding_on failed");
 492                         key_free(k);
 493                         goto send;
 494                 }
 495                 break;
 496         }
 497         comment = buffer_get_string(&e->request, NULL);
 498         if (k == NULL) {
 499                 xfree(comment);
 500                 goto send;
 501         }
 502         success = 1;
 503         while (buffer_len(&e->request)) {
 504                 switch (buffer_get_char(&e->request)) {
 505                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 506                         death = time(NULL) + buffer_get_int(&e->request);
 507                         break;
 508                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 509                         confirm = 1;
 510                         break;
 511                 default:
 512                         break;
 513                 }
 514         }
 515         if (lifetime && !death)
 516                 death = time(NULL) + lifetime;
 517         if (lookup_identity(k, version) == NULL) {
 518                 Identity *id = xmalloc(sizeof(Identity));
 519                 id->key = k;
 520                 id->comment = comment;
 521                 id->death = death;
 522                 id->confirm = confirm;
 523                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 524                 /* Increment the number of identities. */
 525                 tab->nentries++;
 526         } else {
 527                 key_free(k);
 528                 xfree(comment);
 529         }
 530 send:
 531         buffer_put_int(&e->output, 1);
 532         buffer_put_char(&e->output,
 533             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 534 }
 535
 536 /* XXX todo: encrypt sensitive data with passphrase */
 537 static void
 538 process_lock_agent(SocketEntry *e, int lock)
 539 {
 540         int success = 0;
 541         char *passwd;
 542
 543         passwd = buffer_get_string(&e->request, NULL);
 544         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 545                 locked = 0;
 546                 memset(lock_passwd, 0, strlen(lock_passwd));
 547                 xfree(lock_passwd);
 548                 lock_passwd = NULL;
 549                 success = 1;
 550         } else if (!locked && lock) {
 551                 locked = 1;
 552                 lock_passwd = xstrdup(passwd);
 553                 success = 1;
 554         }
 555         memset(passwd, 0, strlen(passwd));
 556         xfree(passwd);
 557
 558         buffer_put_int(&e->output, 1);
 559         buffer_put_char(&e->output,
 560             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 561 }
 562
 563 static void
 564 no_identities(SocketEntry *e, u_int type)
 565 {
 566         Buffer msg;
 567
 568         buffer_init(&msg);
 569         buffer_put_char(&msg,
 570             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 571             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 572         buffer_put_int(&msg, 0);
 573         buffer_put_int(&e->output, buffer_len(&msg));
 574         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 575         buffer_free(&msg);
 576 }
 577
 578 #ifdef SMARTCARD
 579 static void
 580 process_add_smartcard_key (SocketEntry *e)
 581 {
 582         char *sc_reader_id = NULL, *pin;
 583         int i, version, success = 0;
 584         Key **keys, *k;
 585         Identity *id;
 586         Idtab *tab;
 587
 588         sc_reader_id = buffer_get_string(&e->request, NULL);
 589         pin = buffer_get_string(&e->request, NULL);
 590         keys = sc_get_keys(sc_reader_id, pin);
 591         xfree(sc_reader_id);
 592         xfree(pin);
 593
 594         if (keys == NULL || keys[0] == NULL) {
 595                 error("sc_get_keys failed");
 596                 goto send;
 597         }
 598         for (i = 0; keys[i] != NULL; i++) {
 599                 k = keys[i];
 600                 version = k->type == KEY_RSA1 ? 1 : 2;
 601                 tab = idtab_lookup(version);
 602                 if (lookup_identity(k, version) == NULL) {
 603                         id = xmalloc(sizeof(Identity));
 604                         id->key = k;
 605                         id->comment = xstrdup("smartcard key");
 606                         id->death = 0;
 607                         id->confirm = 0;
 608                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 609                         tab->nentries++;
 610                         success = 1;
 611                 } else {
 612                         key_free(k);
 613                 }
 614                 keys[i] = NULL;
 615         }
 616         xfree(keys);
 617 send:
 618         buffer_put_int(&e->output, 1);
 619         buffer_put_char(&e->output,
 620             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 621 }
 622
 623 static void
 624 process_remove_smartcard_key(SocketEntry *e)
 625 {
 626         char *sc_reader_id = NULL, *pin;
 627         int i, version, success = 0;
 628         Key **keys, *k = NULL;
 629         Identity *id;
 630         Idtab *tab;
 631
 632         sc_reader_id = buffer_get_string(&e->request, NULL);
 633         pin = buffer_get_string(&e->request, NULL);
 634         keys = sc_get_keys(sc_reader_id, pin);
 635         xfree(sc_reader_id);
 636         xfree(pin);
 637
 638         if (keys == NULL || keys[0] == NULL) {
 639                 error("sc_get_keys failed");
 640                 goto send;
 641         }
 642         for (i = 0; keys[i] != NULL; i++) {
 643                 k = keys[i];
 644                 version = k->type == KEY_RSA1 ? 1 : 2;
 645                 if ((id = lookup_identity(k, version)) != NULL) {
 646                         tab = idtab_lookup(version);
 647                         TAILQ_REMOVE(&tab->idlist, id, next);
 648                         tab->nentries--;
 649                         free_identity(id);
 650                         success = 1;
 651                 }
 652                 key_free(k);
 653                 keys[i] = NULL;
 654         }
 655         xfree(keys);
 656 send:
 657         buffer_put_int(&e->output, 1);
 658         buffer_put_char(&e->output,
 659             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 660 }
 661 #endif /* SMARTCARD */
 662
 663 /* dispatch incoming messages */
 664
 665 static void
 666 process_message(SocketEntry *e)
 667 {
 668         u_int msg_len, type;
 669         u_char *cp;
 670
 671         /* kill dead keys */
 672         reaper();
 673
 674         if (buffer_len(&e->input) < 5)
 675                 return;         /* Incomplete message. */
 676         cp = buffer_ptr(&e->input);
 677         msg_len = GET_32BIT(cp);
 678         if (msg_len > 256 * 1024) {
 679                 close_socket(e);
 680                 return;
 681         }
 682         if (buffer_len(&e->input) < msg_len + 4)
 683                 return;
 684
 685         /* move the current input to e->request */
 686         buffer_consume(&e->input, 4);
 687         buffer_clear(&e->request);
 688         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 689         buffer_consume(&e->input, msg_len);
 690         type = buffer_get_char(&e->request);
 691
 692         /* check wheter agent is locked */
 693         if (locked && type != SSH_AGENTC_UNLOCK) {
 694                 buffer_clear(&e->request);
 695                 switch (type) {
 696                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 697                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 698                         /* send empty lists */
 699                         no_identities(e, type);
 700                         break;
 701                 default:
 702                         /* send a fail message for all other request types */
 703                         buffer_put_int(&e->output, 1);
 704                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 705                 }
 706                 return;
 707         }
 708
 709         debug("type %d", type);
 710         switch (type) {
 711         case SSH_AGENTC_LOCK:
 712         case SSH_AGENTC_UNLOCK:
 713                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 714                 break;
 715         /* ssh1 */
 716         case SSH_AGENTC_RSA_CHALLENGE:
 717                 process_authentication_challenge1(e);
 718                 break;
 719         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 720                 process_request_identities(e, 1);
 721                 break;
 722         case SSH_AGENTC_ADD_RSA_IDENTITY:
 723         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 724                 process_add_identity(e, 1);
 725                 break;
 726         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 727                 process_remove_identity(e, 1);
 728                 break;
 729         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 730                 process_remove_all_identities(e, 1);
 731                 break;
 732         /* ssh2 */
 733         case SSH2_AGENTC_SIGN_REQUEST:
 734                 process_sign_request2(e);
 735                 break;
 736         case SSH2_AGENTC_REQUEST_IDENTITIES:
 737                 process_request_identities(e, 2);
 738                 break;
 739         case SSH2_AGENTC_ADD_IDENTITY:
 740         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 741                 process_add_identity(e, 2);
 742                 break;
 743         case SSH2_AGENTC_REMOVE_IDENTITY:
 744                 process_remove_identity(e, 2);
 745                 break;
 746         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 747                 process_remove_all_identities(e, 2);
 748                 break;
 749 #ifdef SMARTCARD
 750         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 751                 process_add_smartcard_key(e);
 752                 break;
 753         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 754                 process_remove_smartcard_key(e);
 755                 break;
 756 #endif /* SMARTCARD */
 757         default:
 758                 /* Unknown message.  Respond with failure. */
 759                 error("Unknown message %d", type);
 760                 buffer_clear(&e->request);
 761                 buffer_put_int(&e->output, 1);
 762                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 763                 break;
 764         }
 765 }
 766
 767 static void
 768 new_socket(sock_type type, int fd)
 769 {
 770         u_int i, old_alloc;
 771
 772         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 773                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 774
 775         if (fd > max_fd)
 776                 max_fd = fd;
 777
 778         for (i = 0; i < sockets_alloc; i++)
 779                 if (sockets[i].type == AUTH_UNUSED) {
 780                         sockets[i].fd = fd;
 781                         sockets[i].type = type;
 782                         buffer_init(&sockets[i].input);
 783                         buffer_init(&sockets[i].output);
 784                         buffer_init(&sockets[i].request);
 785                         return;
 786                 }
 787         old_alloc = sockets_alloc;
 788         sockets_alloc += 10;
 789         if (sockets)
 790                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 791         else
 792                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 793         for (i = old_alloc; i < sockets_alloc; i++)
 794                 sockets[i].type = AUTH_UNUSED;
 795         sockets[old_alloc].type = type;
 796         sockets[old_alloc].fd = fd;
 797         buffer_init(&sockets[old_alloc].input);
 798         buffer_init(&sockets[old_alloc].output);
 799         buffer_init(&sockets[old_alloc].request);
 800 }
 801
 802 static int
 803 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 804 {
 805         u_int i, sz;
 806         int n = 0;
 807
 808         for (i = 0; i < sockets_alloc; i++) {
 809                 switch (sockets[i].type) {
 810                 case AUTH_SOCKET:
 811                 case AUTH_CONNECTION:
 812                         n = MAX(n, sockets[i].fd);
 813                         break;
 814                 case AUTH_UNUSED:
 815                         break;
 816                 default:
 817                         fatal("Unknown socket type %d", sockets[i].type);
 818                         break;
 819                 }
 820         }
 821
 822         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 823         if (*fdrp == NULL || sz > *nallocp) {
 824                 if (*fdrp)
 825                         xfree(*fdrp);
 826                 if (*fdwp)
 827                         xfree(*fdwp);
 828                 *fdrp = xmalloc(sz);
 829                 *fdwp = xmalloc(sz);
 830                 *nallocp = sz;
 831         }
 832         if (n < *fdl)
 833                 debug("XXX shrink: %d < %d", n, *fdl);
 834         *fdl = n;
 835         memset(*fdrp, 0, sz);
 836         memset(*fdwp, 0, sz);
 837
 838         for (i = 0; i < sockets_alloc; i++) {
 839                 switch (sockets[i].type) {
 840                 case AUTH_SOCKET:
 841                 case AUTH_CONNECTION:
 842                         FD_SET(sockets[i].fd, *fdrp);
 843                         if (buffer_len(&sockets[i].output) > 0)
 844                                 FD_SET(sockets[i].fd, *fdwp);
 845                         break;
 846                 default:
 847                         break;
 848                 }
 849         }
 850         return (1);
 851 }
 852
 853 static void
 854 after_select(fd_set *readset, fd_set *writeset)
 855 {
 856         struct sockaddr_un sunaddr;
 857         socklen_t slen;
 858         char buf[1024];
 859         int len, sock;
 860         u_int i;
 861         uid_t euid;
 862         gid_t egid;
 863
 864         for (i = 0; i < sockets_alloc; i++)
 865                 switch (sockets[i].type) {
 866                 case AUTH_UNUSED:
 867                         break;
 868                 case AUTH_SOCKET:
 869                         if (FD_ISSET(sockets[i].fd, readset)) {
 870                                 slen = sizeof(sunaddr);
 871                                 sock = accept(sockets[i].fd,
 872                                     (struct sockaddr *) &sunaddr, &slen);
 873                                 if (sock < 0) {
 874                                         error("accept from AUTH_SOCKET: %s",
 875                                             strerror(errno));
 876                                         break;
 877                                 }
 878                                 if (getpeereid(sock, &euid, &egid) < 0) {
 879                                         error("getpeereid %d failed: %s",
 880                                             sock, strerror(errno));
 881                                         close(sock);
 882                                         break;
 883                                 }
 884                                 if ((euid != 0) && (getuid() != euid)) {
 885                                         error("uid mismatch: "
 886                                             "peer euid %u != uid %u",
 887                                             (u_int) euid, (u_int) getuid());
 888                                         close(sock);
 889                                         break;
 890                                 }
 891                                 new_socket(AUTH_CONNECTION, sock);
 892                         }
 893                         break;
 894                 case AUTH_CONNECTION:
 895                         if (buffer_len(&sockets[i].output) > 0 &&
 896                             FD_ISSET(sockets[i].fd, writeset)) {
 897                                 do {
 898                                         len = write(sockets[i].fd,
 899                                             buffer_ptr(&sockets[i].output),
 900                                             buffer_len(&sockets[i].output));
 901                                         if (len == -1 && (errno == EAGAIN ||
 902                                             errno == EINTR))
 903                                                 continue;
 904                                         break;
 905                                 } while (1);
 906                                 if (len <= 0) {
 907                                         close_socket(&sockets[i]);
 908                                         break;
 909                                 }
 910                                 buffer_consume(&sockets[i].output, len);
 911                         }
 912                         if (FD_ISSET(sockets[i].fd, readset)) {
 913                                 do {
 914                                         len = read(sockets[i].fd, buf, sizeof(buf));
 915                                         if (len == -1 && (errno == EAGAIN ||
 916                                             errno == EINTR))
 917                                                 continue;
 918                                         break;
 919                                 } while (1);
 920                                 if (len <= 0) {
 921                                         close_socket(&sockets[i]);
 922                                         break;
 923                                 }
 924                                 buffer_append(&sockets[i].input, buf, len);
 925                                 process_message(&sockets[i]);
 926                         }
 927                         break;
 928                 default:
 929                         fatal("Unknown type %d", sockets[i].type);
 930                 }
 931 }
 932
 933 static void
 934 cleanup_socket(void *p)
 935 {
 936         if (socket_name[0])
 937                 unlink(socket_name);
 938         if (socket_dir[0])
 939                 rmdir(socket_dir);
 940 }
 941
 942 static void
 943 cleanup_exit(int i)
 944 {
 945         cleanup_socket(NULL);
 946         exit(i);
 947 }
 948
 949 static void
 950 cleanup_handler(int sig)
 951 {
 952         cleanup_socket(NULL);
 953         _exit(2);
 954 }
 955
 956 static void
 957 check_parent_exists(int sig)
 958 {
 959         int save_errno = errno;
 960
 961         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 962                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 963                 cleanup_handler(sig); /* safe */
 964         }
 965         signal(SIGALRM, check_parent_exists);
 966         alarm(10);
 967         errno = save_errno;
 968 }
 969
 970 static void
 971 usage(void)
 972 {
 973         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 974             __progname);
 975         fprintf(stderr, "Options:\n");
 976         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 977         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 978         fprintf(stderr, "  -k          Kill the current agent.\n");
 979         fprintf(stderr, "  -d          Debug mode.\n");
 980         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 981         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
 982         exit(1);
 983 }
 984
 985 int
 986 main(int ac, char **av)
 987 {
 988         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
 989         int sock, fd,  ch, nalloc;
 990         char *shell, *format, *pidstr, *agentsocket = NULL;
 991         fd_set *readsetp = NULL, *writesetp = NULL;
 992         struct sockaddr_un sunaddr;
 993 #ifdef HAVE_SETRLIMIT
 994         struct rlimit rlim;
 995 #endif
 996 #ifdef HAVE_CYGWIN
 997         int prev_mask;
 998 #endif
 999         extern int optind;
1000         extern char *optarg;
1001         pid_t pid;
1002         char pidstrbuf[1 + 3 * sizeof pid];
1003
1004         /* drop */
1005         setegid(getgid());
1006         setgid(getgid());
1007
1008         SSLeay_add_all_algorithms();
1009
1010         __progname = get_progname(av[0]);
1011         init_rng();
1012         seed_rng();
1013
1014         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1015                 switch (ch) {
1016                 case 'c':
1017                         if (s_flag)
1018                                 usage();
1019                         c_flag++;
1020                         break;
1021                 case 'k':
1022                         k_flag++;
1023                         break;
1024                 case 's':
1025                         if (c_flag)
1026                                 usage();
1027                         s_flag++;
1028                         break;
1029                 case 'd':
1030                         if (d_flag)
1031                                 usage();
1032                         d_flag++;
1033                         break;
1034                 case 'a':
1035                         agentsocket = optarg;
1036                         break;
1037                 case 't':
1038                         if ((lifetime = convtime(optarg)) == -1) {
1039                                 fprintf(stderr, "Invalid lifetime\n");
1040                                 usage();
1041                         }
1042                         break;
1043                 default:
1044                         usage();
1045                 }
1046         }
1047         ac -= optind;
1048         av += optind;
1049
1050         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1051                 usage();
1052
1053         if (ac == 0 && !c_flag && !s_flag) {
1054                 shell = getenv("SHELL");
1055                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1056                         c_flag = 1;
1057         }
1058         if (k_flag) {
1059                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1060                 if (pidstr == NULL) {
1061                         fprintf(stderr, "%s not set, cannot kill agent\n",
1062                             SSH_AGENTPID_ENV_NAME);
1063                         exit(1);
1064                 }
1065                 pid = atoi(pidstr);
1066                 if (pid < 1) {
1067                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
1068                             SSH_AGENTPID_ENV_NAME, pidstr);
1069                         exit(1);
1070                 }
1071                 if (kill(pid, SIGTERM) == -1) {
1072                         perror("kill");
1073                         exit(1);
1074                 }
1075                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1076                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1077                 printf(format, SSH_AGENTPID_ENV_NAME);
1078                 printf("echo Agent pid %ld killed;\n", (long)pid);
1079                 exit(0);
1080         }
1081         parent_pid = getpid();
1082
1083         if (agentsocket == NULL) {
1084                 /* Create private directory for agent socket */
1085                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
1086                 if (mkdtemp(socket_dir) == NULL) {
1087                         perror("mkdtemp: private socket dir");
1088                         exit(1);
1089                 }
1090                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1091                     (long)parent_pid);
1092         } else {
1093                 /* Try to use specified agent socket */
1094                 socket_dir[0] = '\0';
1095                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1096         }
1097
1098         /*
1099          * Create socket early so it will exist before command gets run from
1100          * the parent.
1101          */
1102         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1103         if (sock < 0) {
1104                 perror("socket");
1105                 cleanup_exit(1);
1106         }
1107         memset(&sunaddr, 0, sizeof(sunaddr));
1108         sunaddr.sun_family = AF_UNIX;
1109         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1110 #ifdef HAVE_CYGWIN
1111         prev_mask = umask(0177);
1112 #endif
1113         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1114                 perror("bind");
1115 #ifdef HAVE_CYGWIN
1116                 umask(prev_mask);
1117 #endif
1118                 cleanup_exit(1);
1119         }
1120 #ifdef HAVE_CYGWIN
1121         umask(prev_mask);
1122 #endif
1123         if (listen(sock, 128) < 0) {
1124                 perror("listen");
1125                 cleanup_exit(1);
1126         }
1127
1128         /*
1129          * Fork, and have the parent execute the command, if any, or present
1130          * the socket data.  The child continues as the authentication agent.
1131          */
1132         if (d_flag) {
1133                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1134                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1135                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1136                     SSH_AUTHSOCKET_ENV_NAME);
1137                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1138                 goto skip;
1139         }
1140         pid = fork();
1141         if (pid == -1) {
1142                 perror("fork");
1143                 cleanup_exit(1);
1144         }
1145         if (pid != 0) {         /* Parent - execute the given command. */
1146                 close(sock);
1147                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1148                 if (ac == 0) {
1149                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1150                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1151                             SSH_AUTHSOCKET_ENV_NAME);
1152                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1153                             SSH_AGENTPID_ENV_NAME);
1154                         printf("echo Agent pid %ld;\n", (long)pid);
1155                         exit(0);
1156                 }
1157                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1158                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1159                         perror("setenv");
1160                         exit(1);
1161                 }
1162                 execvp(av[0], av);
1163                 perror(av[0]);
1164                 exit(1);
1165         }
1166         /* child */
1167         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1168
1169         if (setsid() == -1) {
1170                 error("setsid: %s", strerror(errno));
1171                 cleanup_exit(1);
1172         }
1173
1174         (void)chdir("/");
1175         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1176                 /* XXX might close listen socket */
1177                 (void)dup2(fd, STDIN_FILENO);
1178                 (void)dup2(fd, STDOUT_FILENO);
1179                 (void)dup2(fd, STDERR_FILENO);
1180                 if (fd > 2)
1181                         close(fd);
1182         }
1183
1184 #ifdef HAVE_SETRLIMIT
1185         /* deny core dumps, since memory contains unencrypted private keys */
1186         rlim.rlim_cur = rlim.rlim_max = 0;
1187         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1188                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1189                 cleanup_exit(1);
1190         }
1191 #endif
1192
1193 skip:
1194         fatal_add_cleanup(cleanup_socket, NULL);
1195         new_socket(AUTH_SOCKET, sock);
1196         if (ac > 0) {
1197                 signal(SIGALRM, check_parent_exists);
1198                 alarm(10);
1199         }
1200         idtab_init();
1201         if (!d_flag)
1202                 signal(SIGINT, SIG_IGN);
1203         signal(SIGPIPE, SIG_IGN);
1204         signal(SIGHUP, cleanup_handler);
1205         signal(SIGTERM, cleanup_handler);
1206         nalloc = 0;
1207
1208         while (1) {
1209                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1210                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1211                         if (errno == EINTR)
1212                                 continue;
1213                         fatal("select: %s", strerror(errno));
1214                 }
1215                 after_select(readsetp, writesetp);
1216         }
1217         /* NOTREACHED */
1218 }