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 1.106 2003/01/21 18:14:36 marc 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
  54 #ifdef SMARTCARD
  55 #include "scard.h"
  56 #endif
  57
  58 typedef enum {
  59         AUTH_UNUSED,
  60         AUTH_SOCKET,
  61         AUTH_CONNECTION
  62 } sock_type;
  63
  64 typedef struct {
  65         int fd;
  66         sock_type type;
  67         Buffer input;
  68         Buffer output;
  69         Buffer request;
  70 } SocketEntry;
  71
  72 u_int sockets_alloc = 0;
  73 SocketEntry *sockets = NULL;
  74
  75 typedef struct identity {
  76         TAILQ_ENTRY(identity) next;
  77         Key *key;
  78         char *comment;
  79         u_int death;
  80 } Identity;
  81
  82 typedef struct {
  83         int nentries;
  84         TAILQ_HEAD(idqueue, identity) idlist;
  85 } Idtab;
  86
  87 /* private key table, one per protocol version */
  88 Idtab idtable[3];
  89
  90 int max_fd = 0;
  91
  92 /* pid of shell == parent of agent */
  93 pid_t parent_pid = -1;
  94
  95 /* pathname and directory for AUTH_SOCKET */
  96 char socket_name[1024];
  97 char socket_dir[1024];
  98
  99 /* locking */
 100 int locked = 0;
 101 char *lock_passwd = NULL;
 102
 103 #ifdef HAVE___PROGNAME
 104 extern char *__progname;
 105 #else
 106 char *__progname;
 107 #endif
 108
 109 /* Default lifetime (0 == forever) */
 110 static int lifetime = 0;
 111
 112 static void
 113 close_socket(SocketEntry *e)
 114 {
 115         close(e->fd);
 116         e->fd = -1;
 117         e->type = AUTH_UNUSED;
 118         buffer_free(&e->input);
 119         buffer_free(&e->output);
 120         buffer_free(&e->request);
 121 }
 122
 123 static void
 124 idtab_init(void)
 125 {
 126         int i;
 127
 128         for (i = 0; i <=2; i++) {
 129                 TAILQ_INIT(&idtable[i].idlist);
 130                 idtable[i].nentries = 0;
 131         }
 132 }
 133
 134 /* return private key table for requested protocol version */
 135 static Idtab *
 136 idtab_lookup(int version)
 137 {
 138         if (version < 1 || version > 2)
 139                 fatal("internal error, bad protocol version %d", version);
 140         return &idtable[version];
 141 }
 142
 143 static void
 144 free_identity(Identity *id)
 145 {
 146         key_free(id->key);
 147         xfree(id->comment);
 148         xfree(id);
 149 }
 150
 151 /* return matching private key for given public key */
 152 static Identity *
 153 lookup_identity(Key *key, int version)
 154 {
 155         Identity *id;
 156
 157         Idtab *tab = idtab_lookup(version);
 158         TAILQ_FOREACH(id, &tab->idlist, next) {
 159                 if (key_equal(key, id->key))
 160                         return (id);
 161         }
 162         return (NULL);
 163 }
 164
 165 /* send list of supported public keys to 'client' */
 166 static void
 167 process_request_identities(SocketEntry *e, int version)
 168 {
 169         Idtab *tab = idtab_lookup(version);
 170         Identity *id;
 171         Buffer msg;
 172
 173         buffer_init(&msg);
 174         buffer_put_char(&msg, (version == 1) ?
 175             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 176         buffer_put_int(&msg, tab->nentries);
 177         TAILQ_FOREACH(id, &tab->idlist, next) {
 178                 if (id->key->type == KEY_RSA1) {
 179                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 180                         buffer_put_bignum(&msg, id->key->rsa->e);
 181                         buffer_put_bignum(&msg, id->key->rsa->n);
 182                 } else {
 183                         u_char *blob;
 184                         u_int blen;
 185                         key_to_blob(id->key, &blob, &blen);
 186                         buffer_put_string(&msg, blob, blen);
 187                         xfree(blob);
 188                 }
 189                 buffer_put_cstring(&msg, id->comment);
 190         }
 191         buffer_put_int(&e->output, buffer_len(&msg));
 192         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 193         buffer_free(&msg);
 194 }
 195
 196 /* ssh1 only */
 197 static void
 198 process_authentication_challenge1(SocketEntry *e)
 199 {
 200         u_char buf[32], mdbuf[16], session_id[16];
 201         u_int response_type;
 202         BIGNUM *challenge;
 203         Identity *id;
 204         int i, len;
 205         Buffer msg;
 206         MD5_CTX md;
 207         Key *key;
 208
 209         buffer_init(&msg);
 210         key = key_new(KEY_RSA1);
 211         if ((challenge = BN_new()) == NULL)
 212                 fatal("process_authentication_challenge1: BN_new failed");
 213
 214         (void) buffer_get_int(&e->request);                     /* ignored */
 215         buffer_get_bignum(&e->request, key->rsa->e);
 216         buffer_get_bignum(&e->request, key->rsa->n);
 217         buffer_get_bignum(&e->request, challenge);
 218
 219         /* Only protocol 1.1 is supported */
 220         if (buffer_len(&e->request) == 0)
 221                 goto failure;
 222         buffer_get(&e->request, session_id, 16);
 223         response_type = buffer_get_int(&e->request);
 224         if (response_type != 1)
 225                 goto failure;
 226
 227         id = lookup_identity(key, 1);
 228         if (id != NULL) {
 229                 Key *private = id->key;
 230                 /* Decrypt the challenge using the private key. */
 231                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 232                         goto failure;
 233
 234                 /* The response is MD5 of decrypted challenge plus session id. */
 235                 len = BN_num_bytes(challenge);
 236                 if (len <= 0 || len > 32) {
 237                         log("process_authentication_challenge: bad challenge length %d", len);
 238                         goto failure;
 239                 }
 240                 memset(buf, 0, 32);
 241                 BN_bn2bin(challenge, buf + 32 - len);
 242                 MD5_Init(&md);
 243                 MD5_Update(&md, buf, 32);
 244                 MD5_Update(&md, session_id, 16);
 245                 MD5_Final(mdbuf, &md);
 246
 247                 /* Send the response. */
 248                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 249                 for (i = 0; i < 16; i++)
 250                         buffer_put_char(&msg, mdbuf[i]);
 251                 goto send;
 252         }
 253
 254 failure:
 255         /* Unknown identity or protocol error.  Send failure. */
 256         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 257 send:
 258         buffer_put_int(&e->output, buffer_len(&msg));
 259         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 260         key_free(key);
 261         BN_clear_free(challenge);
 262         buffer_free(&msg);
 263 }
 264
 265 /* ssh2 only */
 266 static void
 267 process_sign_request2(SocketEntry *e)
 268 {
 269         u_char *blob, *data, *signature = NULL;
 270         u_int blen, dlen, slen = 0;
 271         extern int datafellows;
 272         int ok = -1, flags;
 273         Buffer msg;
 274         Key *key;
 275
 276         datafellows = 0;
 277
 278         blob = buffer_get_string(&e->request, &blen);
 279         data = buffer_get_string(&e->request, &dlen);
 280
 281         flags = buffer_get_int(&e->request);
 282         if (flags & SSH_AGENT_OLD_SIGNATURE)
 283                 datafellows = SSH_BUG_SIGBLOB;
 284
 285         key = key_from_blob(blob, blen);
 286         if (key != NULL) {
 287                 Identity *id = lookup_identity(key, 2);
 288                 if (id != NULL)
 289                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 290         }
 291         key_free(key);
 292         buffer_init(&msg);
 293         if (ok == 0) {
 294                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 295                 buffer_put_string(&msg, signature, slen);
 296         } else {
 297                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 298         }
 299         buffer_put_int(&e->output, buffer_len(&msg));
 300         buffer_append(&e->output, buffer_ptr(&msg),
 301             buffer_len(&msg));
 302         buffer_free(&msg);
 303         xfree(data);
 304         xfree(blob);
 305         if (signature != NULL)
 306                 xfree(signature);
 307 }
 308
 309 /* shared */
 310 static void
 311 process_remove_identity(SocketEntry *e, int version)
 312 {
 313         u_int blen, bits;
 314         int success = 0;
 315         Key *key = NULL;
 316         u_char *blob;
 317
 318         switch (version) {
 319         case 1:
 320                 key = key_new(KEY_RSA1);
 321                 bits = buffer_get_int(&e->request);
 322                 buffer_get_bignum(&e->request, key->rsa->e);
 323                 buffer_get_bignum(&e->request, key->rsa->n);
 324
 325                 if (bits != key_size(key))
 326                         log("Warning: identity keysize mismatch: actual %u, announced %u",
 327                             key_size(key), bits);
 328                 break;
 329         case 2:
 330                 blob = buffer_get_string(&e->request, &blen);
 331                 key = key_from_blob(blob, blen);
 332                 xfree(blob);
 333                 break;
 334         }
 335         if (key != NULL) {
 336                 Identity *id = lookup_identity(key, version);
 337                 if (id != NULL) {
 338                         /*
 339                          * We have this key.  Free the old key.  Since we
 340                          * don\'t want to leave empty slots in the middle of
 341                          * the array, we actually free the key there and move
 342                          * all the entries between the empty slot and the end
 343                          * of the array.
 344                          */
 345                         Idtab *tab = idtab_lookup(version);
 346                         if (tab->nentries < 1)
 347                                 fatal("process_remove_identity: "
 348                                     "internal error: tab->nentries %d",
 349                                     tab->nentries);
 350                         TAILQ_REMOVE(&tab->idlist, id, next);
 351                         free_identity(id);
 352                         tab->nentries--;
 353                         success = 1;
 354                 }
 355                 key_free(key);
 356         }
 357         buffer_put_int(&e->output, 1);
 358         buffer_put_char(&e->output,
 359             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 360 }
 361
 362 static void
 363 process_remove_all_identities(SocketEntry *e, int version)
 364 {
 365         Idtab *tab = idtab_lookup(version);
 366         Identity *id;
 367
 368         /* Loop over all identities and clear the keys. */
 369         for (id = TAILQ_FIRST(&tab->idlist); id;
 370             id = TAILQ_FIRST(&tab->idlist)) {
 371                 TAILQ_REMOVE(&tab->idlist, id, next);
 372                 free_identity(id);
 373         }
 374
 375         /* Mark that there are no identities. */
 376         tab->nentries = 0;
 377
 378         /* Send success. */
 379         buffer_put_int(&e->output, 1);
 380         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 381 }
 382
 383 static void
 384 reaper(void)
 385 {
 386         u_int now = time(NULL);
 387         Identity *id, *nxt;
 388         int version;
 389         Idtab *tab;
 390
 391         for (version = 1; version < 3; version++) {
 392                 tab = idtab_lookup(version);
 393                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 394                         nxt = TAILQ_NEXT(id, next);
 395                         if (id->death != 0 && now >= id->death) {
 396                                 TAILQ_REMOVE(&tab->idlist, id, next);
 397                                 free_identity(id);
 398                                 tab->nentries--;
 399                         }
 400                 }
 401         }
 402 }
 403
 404 static void
 405 process_add_identity(SocketEntry *e, int version)
 406 {
 407         Idtab *tab = idtab_lookup(version);
 408         int type, success = 0, death = 0;
 409         char *type_name, *comment;
 410         Key *k = NULL;
 411
 412         switch (version) {
 413         case 1:
 414                 k = key_new_private(KEY_RSA1);
 415                 (void) buffer_get_int(&e->request);             /* ignored */
 416                 buffer_get_bignum(&e->request, k->rsa->n);
 417                 buffer_get_bignum(&e->request, k->rsa->e);
 418                 buffer_get_bignum(&e->request, k->rsa->d);
 419                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 420
 421                 /* SSH and SSL have p and q swapped */
 422                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 423                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 424
 425                 /* Generate additional parameters */
 426                 rsa_generate_additional_parameters(k->rsa);
 427                 break;
 428         case 2:
 429                 type_name = buffer_get_string(&e->request, NULL);
 430                 type = key_type_from_name(type_name);
 431                 xfree(type_name);
 432                 switch (type) {
 433                 case KEY_DSA:
 434                         k = key_new_private(type);
 435                         buffer_get_bignum2(&e->request, k->dsa->p);
 436                         buffer_get_bignum2(&e->request, k->dsa->q);
 437                         buffer_get_bignum2(&e->request, k->dsa->g);
 438                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 439                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 440                         break;
 441                 case KEY_RSA:
 442                         k = key_new_private(type);
 443                         buffer_get_bignum2(&e->request, k->rsa->n);
 444                         buffer_get_bignum2(&e->request, k->rsa->e);
 445                         buffer_get_bignum2(&e->request, k->rsa->d);
 446                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 447                         buffer_get_bignum2(&e->request, k->rsa->p);
 448                         buffer_get_bignum2(&e->request, k->rsa->q);
 449
 450                         /* Generate additional parameters */
 451                         rsa_generate_additional_parameters(k->rsa);
 452                         break;
 453                 default:
 454                         buffer_clear(&e->request);
 455                         goto send;
 456                 }
 457                 break;
 458         }
 459         comment = buffer_get_string(&e->request, NULL);
 460         if (k == NULL) {
 461                 xfree(comment);
 462                 goto send;
 463         }
 464         success = 1;
 465         while (buffer_len(&e->request)) {
 466                 switch (buffer_get_char(&e->request)) {
 467                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 468                         death = time(NULL) + buffer_get_int(&e->request);
 469                         break;
 470                 default:
 471                         break;
 472                 }
 473         }
 474         if (lifetime && !death)
 475                 death = time(NULL) + lifetime;
 476         if (lookup_identity(k, version) == NULL) {
 477                 Identity *id = xmalloc(sizeof(Identity));
 478                 id->key = k;
 479                 id->comment = comment;
 480                 id->death = death;
 481                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 482                 /* Increment the number of identities. */
 483                 tab->nentries++;
 484         } else {
 485                 key_free(k);
 486                 xfree(comment);
 487         }
 488 send:
 489         buffer_put_int(&e->output, 1);
 490         buffer_put_char(&e->output,
 491             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 492 }
 493
 494 /* XXX todo: encrypt sensitive data with passphrase */
 495 static void
 496 process_lock_agent(SocketEntry *e, int lock)
 497 {
 498         int success = 0;
 499         char *passwd;
 500
 501         passwd = buffer_get_string(&e->request, NULL);
 502         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 503                 locked = 0;
 504                 memset(lock_passwd, 0, strlen(lock_passwd));
 505                 xfree(lock_passwd);
 506                 lock_passwd = NULL;
 507                 success = 1;
 508         } else if (!locked && lock) {
 509                 locked = 1;
 510                 lock_passwd = xstrdup(passwd);
 511                 success = 1;
 512         }
 513         memset(passwd, 0, strlen(passwd));
 514         xfree(passwd);
 515
 516         buffer_put_int(&e->output, 1);
 517         buffer_put_char(&e->output,
 518             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 519 }
 520
 521 static void
 522 no_identities(SocketEntry *e, u_int type)
 523 {
 524         Buffer msg;
 525
 526         buffer_init(&msg);
 527         buffer_put_char(&msg,
 528             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 529             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 530         buffer_put_int(&msg, 0);
 531         buffer_put_int(&e->output, buffer_len(&msg));
 532         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 533         buffer_free(&msg);
 534 }
 535
 536 #ifdef SMARTCARD
 537 static void
 538 process_add_smartcard_key (SocketEntry *e)
 539 {
 540         char *sc_reader_id = NULL, *pin;
 541         int i, version, success = 0;
 542         Key **keys, *k;
 543         Identity *id;
 544         Idtab *tab;
 545
 546         sc_reader_id = buffer_get_string(&e->request, NULL);
 547         pin = buffer_get_string(&e->request, NULL);
 548         keys = sc_get_keys(sc_reader_id, pin);
 549         xfree(sc_reader_id);
 550         xfree(pin);
 551
 552         if (keys == NULL || keys[0] == NULL) {
 553                 error("sc_get_keys failed");
 554                 goto send;
 555         }
 556         for (i = 0; keys[i] != NULL; i++) {
 557                 k = keys[i];
 558                 version = k->type == KEY_RSA1 ? 1 : 2;
 559                 tab = idtab_lookup(version);
 560                 if (lookup_identity(k, version) == NULL) {
 561                         id = xmalloc(sizeof(Identity));
 562                         id->key = k;
 563                         id->comment = xstrdup("smartcard key");
 564                         id->death = 0;
 565                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 566                         tab->nentries++;
 567                         success = 1;
 568                 } else {
 569                         key_free(k);
 570                 }
 571                 keys[i] = NULL;
 572         }
 573         xfree(keys);
 574 send:
 575         buffer_put_int(&e->output, 1);
 576         buffer_put_char(&e->output,
 577             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 578 }
 579
 580 static void
 581 process_remove_smartcard_key(SocketEntry *e)
 582 {
 583         char *sc_reader_id = NULL, *pin;
 584         int i, version, success = 0;
 585         Key **keys, *k = NULL;
 586         Identity *id;
 587         Idtab *tab;
 588
 589         sc_reader_id = buffer_get_string(&e->request, NULL);
 590         pin = buffer_get_string(&e->request, NULL);
 591         keys = sc_get_keys(sc_reader_id, pin);
 592         xfree(sc_reader_id);
 593         xfree(pin);
 594
 595         if (keys == NULL || keys[0] == NULL) {
 596                 error("sc_get_keys failed");
 597                 goto send;
 598         }
 599         for (i = 0; keys[i] != NULL; i++) {
 600                 k = keys[i];
 601                 version = k->type == KEY_RSA1 ? 1 : 2;
 602                 if ((id = lookup_identity(k, version)) != NULL) {
 603                         tab = idtab_lookup(version);
 604                         TAILQ_REMOVE(&tab->idlist, id, next);
 605                         tab->nentries--;
 606                         free_identity(id);
 607                         success = 1;
 608                 }
 609                 key_free(k);
 610                 keys[i] = NULL;
 611         }
 612         xfree(keys);
 613 send:
 614         buffer_put_int(&e->output, 1);
 615         buffer_put_char(&e->output,
 616             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 617 }
 618 #endif /* SMARTCARD */
 619
 620 /* dispatch incoming messages */
 621
 622 static void
 623 process_message(SocketEntry *e)
 624 {
 625         u_int msg_len, type;
 626         u_char *cp;
 627
 628         /* kill dead keys */
 629         reaper();
 630
 631         if (buffer_len(&e->input) < 5)
 632                 return;         /* Incomplete message. */
 633         cp = buffer_ptr(&e->input);
 634         msg_len = GET_32BIT(cp);
 635         if (msg_len > 256 * 1024) {
 636                 close_socket(e);
 637                 return;
 638         }
 639         if (buffer_len(&e->input) < msg_len + 4)
 640                 return;
 641
 642         /* move the current input to e->request */
 643         buffer_consume(&e->input, 4);
 644         buffer_clear(&e->request);
 645         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 646         buffer_consume(&e->input, msg_len);
 647         type = buffer_get_char(&e->request);
 648
 649         /* check wheter agent is locked */
 650         if (locked && type != SSH_AGENTC_UNLOCK) {
 651                 buffer_clear(&e->request);
 652                 switch (type) {
 653                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 654                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 655                         /* send empty lists */
 656                         no_identities(e, type);
 657                         break;
 658                 default:
 659                         /* send a fail message for all other request types */
 660                         buffer_put_int(&e->output, 1);
 661                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 662                 }
 663                 return;
 664         }
 665
 666         debug("type %d", type);
 667         switch (type) {
 668         case SSH_AGENTC_LOCK:
 669         case SSH_AGENTC_UNLOCK:
 670                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 671                 break;
 672         /* ssh1 */
 673         case SSH_AGENTC_RSA_CHALLENGE:
 674                 process_authentication_challenge1(e);
 675                 break;
 676         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 677                 process_request_identities(e, 1);
 678                 break;
 679         case SSH_AGENTC_ADD_RSA_IDENTITY:
 680         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 681                 process_add_identity(e, 1);
 682                 break;
 683         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 684                 process_remove_identity(e, 1);
 685                 break;
 686         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 687                 process_remove_all_identities(e, 1);
 688                 break;
 689         /* ssh2 */
 690         case SSH2_AGENTC_SIGN_REQUEST:
 691                 process_sign_request2(e);
 692                 break;
 693         case SSH2_AGENTC_REQUEST_IDENTITIES:
 694                 process_request_identities(e, 2);
 695                 break;
 696         case SSH2_AGENTC_ADD_IDENTITY:
 697         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 698                 process_add_identity(e, 2);
 699                 break;
 700         case SSH2_AGENTC_REMOVE_IDENTITY:
 701                 process_remove_identity(e, 2);
 702                 break;
 703         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 704                 process_remove_all_identities(e, 2);
 705                 break;
 706 #ifdef SMARTCARD
 707         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 708                 process_add_smartcard_key(e);
 709                 break;
 710         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 711                 process_remove_smartcard_key(e);
 712                 break;
 713 #endif /* SMARTCARD */
 714         default:
 715                 /* Unknown message.  Respond with failure. */
 716                 error("Unknown message %d", type);
 717                 buffer_clear(&e->request);
 718                 buffer_put_int(&e->output, 1);
 719                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 720                 break;
 721         }
 722 }
 723
 724 static void
 725 new_socket(sock_type type, int fd)
 726 {
 727         u_int i, old_alloc;
 728
 729         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 730                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 731
 732         if (fd > max_fd)
 733                 max_fd = fd;
 734
 735         for (i = 0; i < sockets_alloc; i++)
 736                 if (sockets[i].type == AUTH_UNUSED) {
 737                         sockets[i].fd = fd;
 738                         sockets[i].type = type;
 739                         buffer_init(&sockets[i].input);
 740                         buffer_init(&sockets[i].output);
 741                         buffer_init(&sockets[i].request);
 742                         return;
 743                 }
 744         old_alloc = sockets_alloc;
 745         sockets_alloc += 10;
 746         if (sockets)
 747                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 748         else
 749                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 750         for (i = old_alloc; i < sockets_alloc; i++)
 751                 sockets[i].type = AUTH_UNUSED;
 752         sockets[old_alloc].type = type;
 753         sockets[old_alloc].fd = fd;
 754         buffer_init(&sockets[old_alloc].input);
 755         buffer_init(&sockets[old_alloc].output);
 756         buffer_init(&sockets[old_alloc].request);
 757 }
 758
 759 static int
 760 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 761 {
 762         u_int i, sz;
 763         int n = 0;
 764
 765         for (i = 0; i < sockets_alloc; i++) {
 766                 switch (sockets[i].type) {
 767                 case AUTH_SOCKET:
 768                 case AUTH_CONNECTION:
 769                         n = MAX(n, sockets[i].fd);
 770                         break;
 771                 case AUTH_UNUSED:
 772                         break;
 773                 default:
 774                         fatal("Unknown socket type %d", sockets[i].type);
 775                         break;
 776                 }
 777         }
 778
 779         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 780         if (*fdrp == NULL || sz > *nallocp) {
 781                 if (*fdrp)
 782                         xfree(*fdrp);
 783                 if (*fdwp)
 784                         xfree(*fdwp);
 785                 *fdrp = xmalloc(sz);
 786                 *fdwp = xmalloc(sz);
 787                 *nallocp = sz;
 788         }
 789         if (n < *fdl)
 790                 debug("XXX shrink: %d < %d", n, *fdl);
 791         *fdl = n;
 792         memset(*fdrp, 0, sz);
 793         memset(*fdwp, 0, sz);
 794
 795         for (i = 0; i < sockets_alloc; i++) {
 796                 switch (sockets[i].type) {
 797                 case AUTH_SOCKET:
 798                 case AUTH_CONNECTION:
 799                         FD_SET(sockets[i].fd, *fdrp);
 800                         if (buffer_len(&sockets[i].output) > 0)
 801                                 FD_SET(sockets[i].fd, *fdwp);
 802                         break;
 803                 default:
 804                         break;
 805                 }
 806         }
 807         return (1);
 808 }
 809
 810 static void
 811 after_select(fd_set *readset, fd_set *writeset)
 812 {
 813         struct sockaddr_un sunaddr;
 814         socklen_t slen;
 815         char buf[1024];
 816         int len, sock;
 817         u_int i;
 818         uid_t euid;
 819         gid_t egid;
 820
 821         for (i = 0; i < sockets_alloc; i++)
 822                 switch (sockets[i].type) {
 823                 case AUTH_UNUSED:
 824                         break;
 825                 case AUTH_SOCKET:
 826                         if (FD_ISSET(sockets[i].fd, readset)) {
 827                                 slen = sizeof(sunaddr);
 828                                 sock = accept(sockets[i].fd,
 829                                     (struct sockaddr *) &sunaddr, &slen);
 830                                 if (sock < 0) {
 831                                         error("accept from AUTH_SOCKET: %s",
 832                                             strerror(errno));
 833                                         break;
 834                                 }
 835                                 if (getpeereid(sock, &euid, &egid) < 0) {
 836                                         error("getpeereid %d failed: %s",
 837                                             sock, strerror(errno));
 838                                         close(sock);
 839                                         break;
 840                                 }
 841                                 if ((euid != 0) && (getuid() != euid)) {
 842                                         error("uid mismatch: "
 843                                             "peer euid %u != uid %u",
 844                                             (u_int) euid, (u_int) getuid());
 845                                         close(sock);
 846                                         break;
 847                                 }
 848                                 new_socket(AUTH_CONNECTION, sock);
 849                         }
 850                         break;
 851                 case AUTH_CONNECTION:
 852                         if (buffer_len(&sockets[i].output) > 0 &&
 853                             FD_ISSET(sockets[i].fd, writeset)) {
 854                                 do {
 855                                         len = write(sockets[i].fd,
 856                                             buffer_ptr(&sockets[i].output),
 857                                             buffer_len(&sockets[i].output));
 858                                         if (len == -1 && (errno == EAGAIN ||
 859                                             errno == EINTR))
 860                                                 continue;
 861                                         break;
 862                                 } while (1);
 863                                 if (len <= 0) {
 864                                         close_socket(&sockets[i]);
 865                                         break;
 866                                 }
 867                                 buffer_consume(&sockets[i].output, len);
 868                         }
 869                         if (FD_ISSET(sockets[i].fd, readset)) {
 870                                 do {
 871                                         len = read(sockets[i].fd, buf, sizeof(buf));
 872                                         if (len == -1 && (errno == EAGAIN ||
 873                                             errno == EINTR))
 874                                                 continue;
 875                                         break;
 876                                 } while (1);
 877                                 if (len <= 0) {
 878                                         close_socket(&sockets[i]);
 879                                         break;
 880                                 }
 881                                 buffer_append(&sockets[i].input, buf, len);
 882                                 process_message(&sockets[i]);
 883                         }
 884                         break;
 885                 default:
 886                         fatal("Unknown type %d", sockets[i].type);
 887                 }
 888 }
 889
 890 static void
 891 cleanup_socket(void *p)
 892 {
 893         if (socket_name[0])
 894                 unlink(socket_name);
 895         if (socket_dir[0])
 896                 rmdir(socket_dir);
 897 }
 898
 899 static void
 900 cleanup_exit(int i)
 901 {
 902         cleanup_socket(NULL);
 903         exit(i);
 904 }
 905
 906 static void
 907 cleanup_handler(int sig)
 908 {
 909         cleanup_socket(NULL);
 910         _exit(2);
 911 }
 912
 913 static void
 914 check_parent_exists(int sig)
 915 {
 916         int save_errno = errno;
 917
 918         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 919                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 920                 cleanup_handler(sig); /* safe */
 921         }
 922         signal(SIGALRM, check_parent_exists);
 923         alarm(10);
 924         errno = save_errno;
 925 }
 926
 927 static void
 928 usage(void)
 929 {
 930         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 931             __progname);
 932         fprintf(stderr, "Options:\n");
 933         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 934         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 935         fprintf(stderr, "  -k          Kill the current agent.\n");
 936         fprintf(stderr, "  -d          Debug mode.\n");
 937         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 938         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
 939         exit(1);
 940 }
 941
 942 int
 943 main(int ac, char **av)
 944 {
 945         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 946         char *shell, *format, *pidstr, *agentsocket = NULL;
 947         fd_set *readsetp = NULL, *writesetp = NULL;
 948         struct sockaddr_un sunaddr;
 949 #ifdef HAVE_SETRLIMIT
 950         struct rlimit rlim;
 951 #endif
 952 #ifdef HAVE_CYGWIN
 953         int prev_mask;
 954 #endif
 955         extern int optind;
 956         extern char *optarg;
 957         pid_t pid;
 958         char pidstrbuf[1 + 3 * sizeof pid];
 959
 960         /* drop */
 961         setegid(getgid());
 962         setgid(getgid());
 963
 964         SSLeay_add_all_algorithms();
 965
 966         __progname = get_progname(av[0]);
 967         init_rng();
 968         seed_rng();
 969
 970         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
 971                 switch (ch) {
 972                 case 'c':
 973                         if (s_flag)
 974                                 usage();
 975                         c_flag++;
 976                         break;
 977                 case 'k':
 978                         k_flag++;
 979                         break;
 980                 case 's':
 981                         if (c_flag)
 982                                 usage();
 983                         s_flag++;
 984                         break;
 985                 case 'd':
 986                         if (d_flag)
 987                                 usage();
 988                         d_flag++;
 989                         break;
 990                 case 'a':
 991                         agentsocket = optarg;
 992                         break;
 993                 case 't':
 994                         if ((lifetime = convtime(optarg)) == -1) {
 995                                 fprintf(stderr, "Invalid lifetime\n");
 996                                 usage();
 997                         }
 998                         break;
 999                 default:
1000                         usage();
1001                 }
1002         }
1003         ac -= optind;
1004         av += optind;
1005
1006         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1007                 usage();
1008
1009         if (ac == 0 && !c_flag && !s_flag) {
1010                 shell = getenv("SHELL");
1011                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1012                         c_flag = 1;
1013         }
1014         if (k_flag) {
1015                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1016                 if (pidstr == NULL) {
1017                         fprintf(stderr, "%s not set, cannot kill agent\n",
1018                             SSH_AGENTPID_ENV_NAME);
1019                         exit(1);
1020                 }
1021                 pid = atoi(pidstr);
1022                 if (pid < 1) {
1023                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
1024                             SSH_AGENTPID_ENV_NAME, pidstr);
1025                         exit(1);
1026                 }
1027                 if (kill(pid, SIGTERM) == -1) {
1028                         perror("kill");
1029                         exit(1);
1030                 }
1031                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1032                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1033                 printf(format, SSH_AGENTPID_ENV_NAME);
1034                 printf("echo Agent pid %ld killed;\n", (long)pid);
1035                 exit(0);
1036         }
1037         parent_pid = getpid();
1038
1039         if (agentsocket == NULL) {
1040                 /* Create private directory for agent socket */
1041                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
1042                 if (mkdtemp(socket_dir) == NULL) {
1043                         perror("mkdtemp: private socket dir");
1044                         exit(1);
1045                 }
1046                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1047                     (long)parent_pid);
1048         } else {
1049                 /* Try to use specified agent socket */
1050                 socket_dir[0] = '\0';
1051                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1052         }
1053
1054         /*
1055          * Create socket early so it will exist before command gets run from
1056          * the parent.
1057          */
1058         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1059         if (sock < 0) {
1060                 perror("socket");
1061                 cleanup_exit(1);
1062         }
1063         memset(&sunaddr, 0, sizeof(sunaddr));
1064         sunaddr.sun_family = AF_UNIX;
1065         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1066 #ifdef HAVE_CYGWIN
1067         prev_mask = umask(0177);
1068 #endif
1069         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1070                 perror("bind");
1071 #ifdef HAVE_CYGWIN
1072                 umask(prev_mask);
1073 #endif
1074                 cleanup_exit(1);
1075         }
1076 #ifdef HAVE_CYGWIN
1077         umask(prev_mask);
1078 #endif
1079         if (listen(sock, 128) < 0) {
1080                 perror("listen");
1081                 cleanup_exit(1);
1082         }
1083
1084         /*
1085          * Fork, and have the parent execute the command, if any, or present
1086          * the socket data.  The child continues as the authentication agent.
1087          */
1088         if (d_flag) {
1089                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1090                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1091                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1092                     SSH_AUTHSOCKET_ENV_NAME);
1093                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1094                 goto skip;
1095         }
1096         pid = fork();
1097         if (pid == -1) {
1098                 perror("fork");
1099                 cleanup_exit(1);
1100         }
1101         if (pid != 0) {         /* Parent - execute the given command. */
1102                 close(sock);
1103                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1104                 if (ac == 0) {
1105                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1106                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1107                             SSH_AUTHSOCKET_ENV_NAME);
1108                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1109                             SSH_AGENTPID_ENV_NAME);
1110                         printf("echo Agent pid %ld;\n", (long)pid);
1111                         exit(0);
1112                 }
1113                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1114                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1115                         perror("setenv");
1116                         exit(1);
1117                 }
1118                 execvp(av[0], av);
1119                 perror(av[0]);
1120                 exit(1);
1121         }
1122         /* child */
1123         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1124
1125         if (setsid() == -1) {
1126                 error("setsid: %s", strerror(errno));
1127                 cleanup_exit(1);
1128         }
1129
1130         (void)chdir("/");
1131         close(0);
1132         close(1);
1133         close(2);
1134
1135 #ifdef HAVE_SETRLIMIT
1136         /* deny core dumps, since memory contains unencrypted private keys */
1137         rlim.rlim_cur = rlim.rlim_max = 0;
1138         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1139                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1140                 cleanup_exit(1);
1141         }
1142 #endif
1143
1144 skip:
1145         fatal_add_cleanup(cleanup_socket, NULL);
1146         new_socket(AUTH_SOCKET, sock);
1147         if (ac > 0) {
1148                 signal(SIGALRM, check_parent_exists);
1149                 alarm(10);
1150         }
1151         idtab_init();
1152         if (!d_flag)
1153                 signal(SIGINT, SIG_IGN);
1154         signal(SIGPIPE, SIG_IGN);
1155         signal(SIGHUP, cleanup_handler);
1156         signal(SIGTERM, cleanup_handler);
1157         nalloc = 0;
1158
1159         while (1) {
1160                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1161                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1162                         if (errno == EINTR)
1163                                 continue;
1164                         fatal("select: %s", strerror(errno));
1165                 }
1166                 after_select(readsetp, writesetp);
1167         }
1168         /* NOTREACHED */
1169 }