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 1.107 2003/01/23 13:50:27 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         comment = buffer_get_string(&e->request, NULL);
 487         if (k == NULL) {
 488                 xfree(comment);
 489                 goto send;
 490         }
 491         success = 1;
 492         while (buffer_len(&e->request)) {
 493                 switch (buffer_get_char(&e->request)) {
 494                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 495                         death = time(NULL) + buffer_get_int(&e->request);
 496                         break;
 497                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 498                         confirm = 1;
 499                         break;
 500                 default:
 501                         break;
 502                 }
 503         }
 504         if (lifetime && !death)
 505                 death = time(NULL) + lifetime;
 506         if (lookup_identity(k, version) == NULL) {
 507                 Identity *id = xmalloc(sizeof(Identity));
 508                 id->key = k;
 509                 id->comment = comment;
 510                 id->death = death;
 511                 id->confirm = confirm;
 512                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 513                 /* Increment the number of identities. */
 514                 tab->nentries++;
 515         } else {
 516                 key_free(k);
 517                 xfree(comment);
 518         }
 519 send:
 520         buffer_put_int(&e->output, 1);
 521         buffer_put_char(&e->output,
 522             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 523 }
 524
 525 /* XXX todo: encrypt sensitive data with passphrase */
 526 static void
 527 process_lock_agent(SocketEntry *e, int lock)
 528 {
 529         int success = 0;
 530         char *passwd;
 531
 532         passwd = buffer_get_string(&e->request, NULL);
 533         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 534                 locked = 0;
 535                 memset(lock_passwd, 0, strlen(lock_passwd));
 536                 xfree(lock_passwd);
 537                 lock_passwd = NULL;
 538                 success = 1;
 539         } else if (!locked && lock) {
 540                 locked = 1;
 541                 lock_passwd = xstrdup(passwd);
 542                 success = 1;
 543         }
 544         memset(passwd, 0, strlen(passwd));
 545         xfree(passwd);
 546
 547         buffer_put_int(&e->output, 1);
 548         buffer_put_char(&e->output,
 549             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 550 }
 551
 552 static void
 553 no_identities(SocketEntry *e, u_int type)
 554 {
 555         Buffer msg;
 556
 557         buffer_init(&msg);
 558         buffer_put_char(&msg,
 559             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 560             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 561         buffer_put_int(&msg, 0);
 562         buffer_put_int(&e->output, buffer_len(&msg));
 563         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 564         buffer_free(&msg);
 565 }
 566
 567 #ifdef SMARTCARD
 568 static void
 569 process_add_smartcard_key (SocketEntry *e)
 570 {
 571         char *sc_reader_id = NULL, *pin;
 572         int i, version, success = 0;
 573         Key **keys, *k;
 574         Identity *id;
 575         Idtab *tab;
 576
 577         sc_reader_id = buffer_get_string(&e->request, NULL);
 578         pin = buffer_get_string(&e->request, NULL);
 579         keys = sc_get_keys(sc_reader_id, pin);
 580         xfree(sc_reader_id);
 581         xfree(pin);
 582
 583         if (keys == NULL || keys[0] == NULL) {
 584                 error("sc_get_keys failed");
 585                 goto send;
 586         }
 587         for (i = 0; keys[i] != NULL; i++) {
 588                 k = keys[i];
 589                 version = k->type == KEY_RSA1 ? 1 : 2;
 590                 tab = idtab_lookup(version);
 591                 if (lookup_identity(k, version) == NULL) {
 592                         id = xmalloc(sizeof(Identity));
 593                         id->key = k;
 594                         id->comment = xstrdup("smartcard key");
 595                         id->death = 0;
 596                         id->confirm = 0;
 597                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 598                         tab->nentries++;
 599                         success = 1;
 600                 } else {
 601                         key_free(k);
 602                 }
 603                 keys[i] = NULL;
 604         }
 605         xfree(keys);
 606 send:
 607         buffer_put_int(&e->output, 1);
 608         buffer_put_char(&e->output,
 609             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 610 }
 611
 612 static void
 613 process_remove_smartcard_key(SocketEntry *e)
 614 {
 615         char *sc_reader_id = NULL, *pin;
 616         int i, version, success = 0;
 617         Key **keys, *k = NULL;
 618         Identity *id;
 619         Idtab *tab;
 620
 621         sc_reader_id = buffer_get_string(&e->request, NULL);
 622         pin = buffer_get_string(&e->request, NULL);
 623         keys = sc_get_keys(sc_reader_id, pin);
 624         xfree(sc_reader_id);
 625         xfree(pin);
 626
 627         if (keys == NULL || keys[0] == NULL) {
 628                 error("sc_get_keys failed");
 629                 goto send;
 630         }
 631         for (i = 0; keys[i] != NULL; i++) {
 632                 k = keys[i];
 633                 version = k->type == KEY_RSA1 ? 1 : 2;
 634                 if ((id = lookup_identity(k, version)) != NULL) {
 635                         tab = idtab_lookup(version);
 636                         TAILQ_REMOVE(&tab->idlist, id, next);
 637                         tab->nentries--;
 638                         free_identity(id);
 639                         success = 1;
 640                 }
 641                 key_free(k);
 642                 keys[i] = NULL;
 643         }
 644         xfree(keys);
 645 send:
 646         buffer_put_int(&e->output, 1);
 647         buffer_put_char(&e->output,
 648             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 649 }
 650 #endif /* SMARTCARD */
 651
 652 /* dispatch incoming messages */
 653
 654 static void
 655 process_message(SocketEntry *e)
 656 {
 657         u_int msg_len, type;
 658         u_char *cp;
 659
 660         /* kill dead keys */
 661         reaper();
 662
 663         if (buffer_len(&e->input) < 5)
 664                 return;         /* Incomplete message. */
 665         cp = buffer_ptr(&e->input);
 666         msg_len = GET_32BIT(cp);
 667         if (msg_len > 256 * 1024) {
 668                 close_socket(e);
 669                 return;
 670         }
 671         if (buffer_len(&e->input) < msg_len + 4)
 672                 return;
 673
 674         /* move the current input to e->request */
 675         buffer_consume(&e->input, 4);
 676         buffer_clear(&e->request);
 677         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 678         buffer_consume(&e->input, msg_len);
 679         type = buffer_get_char(&e->request);
 680
 681         /* check wheter agent is locked */
 682         if (locked && type != SSH_AGENTC_UNLOCK) {
 683                 buffer_clear(&e->request);
 684                 switch (type) {
 685                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 686                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 687                         /* send empty lists */
 688                         no_identities(e, type);
 689                         break;
 690                 default:
 691                         /* send a fail message for all other request types */
 692                         buffer_put_int(&e->output, 1);
 693                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 694                 }
 695                 return;
 696         }
 697
 698         debug("type %d", type);
 699         switch (type) {
 700         case SSH_AGENTC_LOCK:
 701         case SSH_AGENTC_UNLOCK:
 702                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 703                 break;
 704         /* ssh1 */
 705         case SSH_AGENTC_RSA_CHALLENGE:
 706                 process_authentication_challenge1(e);
 707                 break;
 708         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 709                 process_request_identities(e, 1);
 710                 break;
 711         case SSH_AGENTC_ADD_RSA_IDENTITY:
 712         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 713                 process_add_identity(e, 1);
 714                 break;
 715         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 716                 process_remove_identity(e, 1);
 717                 break;
 718         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 719                 process_remove_all_identities(e, 1);
 720                 break;
 721         /* ssh2 */
 722         case SSH2_AGENTC_SIGN_REQUEST:
 723                 process_sign_request2(e);
 724                 break;
 725         case SSH2_AGENTC_REQUEST_IDENTITIES:
 726                 process_request_identities(e, 2);
 727                 break;
 728         case SSH2_AGENTC_ADD_IDENTITY:
 729         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 730                 process_add_identity(e, 2);
 731                 break;
 732         case SSH2_AGENTC_REMOVE_IDENTITY:
 733                 process_remove_identity(e, 2);
 734                 break;
 735         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 736                 process_remove_all_identities(e, 2);
 737                 break;
 738 #ifdef SMARTCARD
 739         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 740                 process_add_smartcard_key(e);
 741                 break;
 742         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 743                 process_remove_smartcard_key(e);
 744                 break;
 745 #endif /* SMARTCARD */
 746         default:
 747                 /* Unknown message.  Respond with failure. */
 748                 error("Unknown message %d", type);
 749                 buffer_clear(&e->request);
 750                 buffer_put_int(&e->output, 1);
 751                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 752                 break;
 753         }
 754 }
 755
 756 static void
 757 new_socket(sock_type type, int fd)
 758 {
 759         u_int i, old_alloc;
 760
 761         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 762                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 763
 764         if (fd > max_fd)
 765                 max_fd = fd;
 766
 767         for (i = 0; i < sockets_alloc; i++)
 768                 if (sockets[i].type == AUTH_UNUSED) {
 769                         sockets[i].fd = fd;
 770                         sockets[i].type = type;
 771                         buffer_init(&sockets[i].input);
 772                         buffer_init(&sockets[i].output);
 773                         buffer_init(&sockets[i].request);
 774                         return;
 775                 }
 776         old_alloc = sockets_alloc;
 777         sockets_alloc += 10;
 778         if (sockets)
 779                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 780         else
 781                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 782         for (i = old_alloc; i < sockets_alloc; i++)
 783                 sockets[i].type = AUTH_UNUSED;
 784         sockets[old_alloc].type = type;
 785         sockets[old_alloc].fd = fd;
 786         buffer_init(&sockets[old_alloc].input);
 787         buffer_init(&sockets[old_alloc].output);
 788         buffer_init(&sockets[old_alloc].request);
 789 }
 790
 791 static int
 792 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 793 {
 794         u_int i, sz;
 795         int n = 0;
 796
 797         for (i = 0; i < sockets_alloc; i++) {
 798                 switch (sockets[i].type) {
 799                 case AUTH_SOCKET:
 800                 case AUTH_CONNECTION:
 801                         n = MAX(n, sockets[i].fd);
 802                         break;
 803                 case AUTH_UNUSED:
 804                         break;
 805                 default:
 806                         fatal("Unknown socket type %d", sockets[i].type);
 807                         break;
 808                 }
 809         }
 810
 811         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 812         if (*fdrp == NULL || sz > *nallocp) {
 813                 if (*fdrp)
 814                         xfree(*fdrp);
 815                 if (*fdwp)
 816                         xfree(*fdwp);
 817                 *fdrp = xmalloc(sz);
 818                 *fdwp = xmalloc(sz);
 819                 *nallocp = sz;
 820         }
 821         if (n < *fdl)
 822                 debug("XXX shrink: %d < %d", n, *fdl);
 823         *fdl = n;
 824         memset(*fdrp, 0, sz);
 825         memset(*fdwp, 0, sz);
 826
 827         for (i = 0; i < sockets_alloc; i++) {
 828                 switch (sockets[i].type) {
 829                 case AUTH_SOCKET:
 830                 case AUTH_CONNECTION:
 831                         FD_SET(sockets[i].fd, *fdrp);
 832                         if (buffer_len(&sockets[i].output) > 0)
 833                                 FD_SET(sockets[i].fd, *fdwp);
 834                         break;
 835                 default:
 836                         break;
 837                 }
 838         }
 839         return (1);
 840 }
 841
 842 static void
 843 after_select(fd_set *readset, fd_set *writeset)
 844 {
 845         struct sockaddr_un sunaddr;
 846         socklen_t slen;
 847         char buf[1024];
 848         int len, sock;
 849         u_int i;
 850         uid_t euid;
 851         gid_t egid;
 852
 853         for (i = 0; i < sockets_alloc; i++)
 854                 switch (sockets[i].type) {
 855                 case AUTH_UNUSED:
 856                         break;
 857                 case AUTH_SOCKET:
 858                         if (FD_ISSET(sockets[i].fd, readset)) {
 859                                 slen = sizeof(sunaddr);
 860                                 sock = accept(sockets[i].fd,
 861                                     (struct sockaddr *) &sunaddr, &slen);
 862                                 if (sock < 0) {
 863                                         error("accept from AUTH_SOCKET: %s",
 864                                             strerror(errno));
 865                                         break;
 866                                 }
 867                                 if (getpeereid(sock, &euid, &egid) < 0) {
 868                                         error("getpeereid %d failed: %s",
 869                                             sock, strerror(errno));
 870                                         close(sock);
 871                                         break;
 872                                 }
 873                                 if ((euid != 0) && (getuid() != euid)) {
 874                                         error("uid mismatch: "
 875                                             "peer euid %u != uid %u",
 876                                             (u_int) euid, (u_int) getuid());
 877                                         close(sock);
 878                                         break;
 879                                 }
 880                                 new_socket(AUTH_CONNECTION, sock);
 881                         }
 882                         break;
 883                 case AUTH_CONNECTION:
 884                         if (buffer_len(&sockets[i].output) > 0 &&
 885                             FD_ISSET(sockets[i].fd, writeset)) {
 886                                 do {
 887                                         len = write(sockets[i].fd,
 888                                             buffer_ptr(&sockets[i].output),
 889                                             buffer_len(&sockets[i].output));
 890                                         if (len == -1 && (errno == EAGAIN ||
 891                                             errno == EINTR))
 892                                                 continue;
 893                                         break;
 894                                 } while (1);
 895                                 if (len <= 0) {
 896                                         close_socket(&sockets[i]);
 897                                         break;
 898                                 }
 899                                 buffer_consume(&sockets[i].output, len);
 900                         }
 901                         if (FD_ISSET(sockets[i].fd, readset)) {
 902                                 do {
 903                                         len = read(sockets[i].fd, buf, sizeof(buf));
 904                                         if (len == -1 && (errno == EAGAIN ||
 905                                             errno == EINTR))
 906                                                 continue;
 907                                         break;
 908                                 } while (1);
 909                                 if (len <= 0) {
 910                                         close_socket(&sockets[i]);
 911                                         break;
 912                                 }
 913                                 buffer_append(&sockets[i].input, buf, len);
 914                                 process_message(&sockets[i]);
 915                         }
 916                         break;
 917                 default:
 918                         fatal("Unknown type %d", sockets[i].type);
 919                 }
 920 }
 921
 922 static void
 923 cleanup_socket(void *p)
 924 {
 925         if (socket_name[0])
 926                 unlink(socket_name);
 927         if (socket_dir[0])
 928                 rmdir(socket_dir);
 929 }
 930
 931 static void
 932 cleanup_exit(int i)
 933 {
 934         cleanup_socket(NULL);
 935         exit(i);
 936 }
 937
 938 static void
 939 cleanup_handler(int sig)
 940 {
 941         cleanup_socket(NULL);
 942         _exit(2);
 943 }
 944
 945 static void
 946 check_parent_exists(int sig)
 947 {
 948         int save_errno = errno;
 949
 950         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 951                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 952                 cleanup_handler(sig); /* safe */
 953         }
 954         signal(SIGALRM, check_parent_exists);
 955         alarm(10);
 956         errno = save_errno;
 957 }
 958
 959 static void
 960 usage(void)
 961 {
 962         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 963             __progname);
 964         fprintf(stderr, "Options:\n");
 965         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 966         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 967         fprintf(stderr, "  -k          Kill the current agent.\n");
 968         fprintf(stderr, "  -d          Debug mode.\n");
 969         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 970         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
 971         exit(1);
 972 }
 973
 974 int
 975 main(int ac, char **av)
 976 {
 977         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
 978         int sock, fd,  ch, nalloc;
 979         char *shell, *format, *pidstr, *agentsocket = NULL;
 980         fd_set *readsetp = NULL, *writesetp = NULL;
 981         struct sockaddr_un sunaddr;
 982 #ifdef HAVE_SETRLIMIT
 983         struct rlimit rlim;
 984 #endif
 985 #ifdef HAVE_CYGWIN
 986         int prev_mask;
 987 #endif
 988         extern int optind;
 989         extern char *optarg;
 990         pid_t pid;
 991         char pidstrbuf[1 + 3 * sizeof pid];
 992
 993         /* drop */
 994         setegid(getgid());
 995         setgid(getgid());
 996
 997         SSLeay_add_all_algorithms();
 998
 999         __progname = get_progname(av[0]);
1000         init_rng();
1001         seed_rng();
1002
1003         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1004                 switch (ch) {
1005                 case 'c':
1006                         if (s_flag)
1007                                 usage();
1008                         c_flag++;
1009                         break;
1010                 case 'k':
1011                         k_flag++;
1012                         break;
1013                 case 's':
1014                         if (c_flag)
1015                                 usage();
1016                         s_flag++;
1017                         break;
1018                 case 'd':
1019                         if (d_flag)
1020                                 usage();
1021                         d_flag++;
1022                         break;
1023                 case 'a':
1024                         agentsocket = optarg;
1025                         break;
1026                 case 't':
1027                         if ((lifetime = convtime(optarg)) == -1) {
1028                                 fprintf(stderr, "Invalid lifetime\n");
1029                                 usage();
1030                         }
1031                         break;
1032                 default:
1033                         usage();
1034                 }
1035         }
1036         ac -= optind;
1037         av += optind;
1038
1039         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1040                 usage();
1041
1042         if (ac == 0 && !c_flag && !s_flag) {
1043                 shell = getenv("SHELL");
1044                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1045                         c_flag = 1;
1046         }
1047         if (k_flag) {
1048                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1049                 if (pidstr == NULL) {
1050                         fprintf(stderr, "%s not set, cannot kill agent\n",
1051                             SSH_AGENTPID_ENV_NAME);
1052                         exit(1);
1053                 }
1054                 pid = atoi(pidstr);
1055                 if (pid < 1) {
1056                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
1057                             SSH_AGENTPID_ENV_NAME, pidstr);
1058                         exit(1);
1059                 }
1060                 if (kill(pid, SIGTERM) == -1) {
1061                         perror("kill");
1062                         exit(1);
1063                 }
1064                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1065                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1066                 printf(format, SSH_AGENTPID_ENV_NAME);
1067                 printf("echo Agent pid %ld killed;\n", (long)pid);
1068                 exit(0);
1069         }
1070         parent_pid = getpid();
1071
1072         if (agentsocket == NULL) {
1073                 /* Create private directory for agent socket */
1074                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
1075                 if (mkdtemp(socket_dir) == NULL) {
1076                         perror("mkdtemp: private socket dir");
1077                         exit(1);
1078                 }
1079                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1080                     (long)parent_pid);
1081         } else {
1082                 /* Try to use specified agent socket */
1083                 socket_dir[0] = '\0';
1084                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1085         }
1086
1087         /*
1088          * Create socket early so it will exist before command gets run from
1089          * the parent.
1090          */
1091         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1092         if (sock < 0) {
1093                 perror("socket");
1094                 cleanup_exit(1);
1095         }
1096         memset(&sunaddr, 0, sizeof(sunaddr));
1097         sunaddr.sun_family = AF_UNIX;
1098         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1099 #ifdef HAVE_CYGWIN
1100         prev_mask = umask(0177);
1101 #endif
1102         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1103                 perror("bind");
1104 #ifdef HAVE_CYGWIN
1105                 umask(prev_mask);
1106 #endif
1107                 cleanup_exit(1);
1108         }
1109 #ifdef HAVE_CYGWIN
1110         umask(prev_mask);
1111 #endif
1112         if (listen(sock, 128) < 0) {
1113                 perror("listen");
1114                 cleanup_exit(1);
1115         }
1116
1117         /*
1118          * Fork, and have the parent execute the command, if any, or present
1119          * the socket data.  The child continues as the authentication agent.
1120          */
1121         if (d_flag) {
1122                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1123                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1124                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1125                     SSH_AUTHSOCKET_ENV_NAME);
1126                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1127                 goto skip;
1128         }
1129         pid = fork();
1130         if (pid == -1) {
1131                 perror("fork");
1132                 cleanup_exit(1);
1133         }
1134         if (pid != 0) {         /* Parent - execute the given command. */
1135                 close(sock);
1136                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1137                 if (ac == 0) {
1138                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1139                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1140                             SSH_AUTHSOCKET_ENV_NAME);
1141                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1142                             SSH_AGENTPID_ENV_NAME);
1143                         printf("echo Agent pid %ld;\n", (long)pid);
1144                         exit(0);
1145                 }
1146                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1147                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1148                         perror("setenv");
1149                         exit(1);
1150                 }
1151                 execvp(av[0], av);
1152                 perror(av[0]);
1153                 exit(1);
1154         }
1155         /* child */
1156         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1157
1158         if (setsid() == -1) {
1159                 error("setsid: %s", strerror(errno));
1160                 cleanup_exit(1);
1161         }
1162
1163         (void)chdir("/");
1164         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1165                 /* XXX might close listen socket */
1166                 (void)dup2(fd, STDIN_FILENO);
1167                 (void)dup2(fd, STDOUT_FILENO);
1168                 (void)dup2(fd, STDERR_FILENO);
1169                 if (fd > 2)
1170                         close(fd);
1171         }
1172
1173 #ifdef HAVE_SETRLIMIT
1174         /* deny core dumps, since memory contains unencrypted private keys */
1175         rlim.rlim_cur = rlim.rlim_max = 0;
1176         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1177                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1178                 cleanup_exit(1);
1179         }
1180 #endif
1181
1182 skip:
1183         fatal_add_cleanup(cleanup_socket, NULL);
1184         new_socket(AUTH_SOCKET, sock);
1185         if (ac > 0) {
1186                 signal(SIGALRM, check_parent_exists);
1187                 alarm(10);
1188         }
1189         idtab_init();
1190         if (!d_flag)
1191                 signal(SIGINT, SIG_IGN);
1192         signal(SIGPIPE, SIG_IGN);
1193         signal(SIGHUP, cleanup_handler);
1194         signal(SIGTERM, cleanup_handler);
1195         nalloc = 0;
1196
1197         while (1) {
1198                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1199                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1200                         if (errno == EINTR)
1201                                 continue;
1202                         fatal("select: %s", strerror(errno));
1203                 }
1204                 after_select(readsetp, writesetp);
1205         }
1206         /* NOTREACHED */
1207 }