crypto/openssh/ssh-agent.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * The authentication agent program.
   6  *
   7  * As far as I am concerned, the code I have written for this software
   8  * can be used freely for any purpose.  Any derived versions of this
   9  * software must be clearly marked as such, and if the derived work is
  10  * incompatible with the protocol description in the RFC file, it must be
  11  * called by a name other than "ssh" or "Secure Shell".
  12  *
  13  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  14  *
  15  * Redistribution and use in source and binary forms, with or without
  16  * modification, are permitted provided that the following conditions
  17  * are met:
  18  * 1. Redistributions of source code must retain the above copyright
  19  *    notice, this list of conditions and the following disclaimer.
  20  * 2. Redistributions in binary form must reproduce the above copyright
  21  *    notice, this list of conditions and the following disclaimer in the
  22  *    documentation and/or other materials provided with the distribution.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  27  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  28  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  29  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  30  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  31  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  32  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  33  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 #include "includes.h"
  37 #include "openbsd-compat/sys-queue.h"
  38 RCSID("$OpenBSD: ssh-agent.c,v 1.105 2002/10/01 20:34:12 markus Exp $");
  39 RCSID("$FreeBSD: src/crypto/openssh/ssh-agent.c,v 1.2.2.10 2003/02/11 08:27:40 des Exp $");
  40 RCSID("$DragonFly: src/crypto/openssh/Attic/ssh-agent.c,v 1.2 2003/06/17 04:24:36 dillon Exp $");
  41
  42 #include <openssl/evp.h>
  43 #include <openssl/md5.h>
  44
  45 #include "ssh.h"
  46 #include "rsa.h"
  47 #include "buffer.h"
  48 #include "bufaux.h"
  49 #include "xmalloc.h"
  50 #include "getput.h"
  51 #include "key.h"
  52 #include "authfd.h"
  53 #include "compat.h"
  54 #include "log.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 } Identity;
  83
  84 typedef struct {
  85         int nentries;
  86         TAILQ_HEAD(idqueue, identity) idlist;
  87 } Idtab;
  88
  89 /* private key table, one per protocol version */
  90 Idtab idtable[3];
  91
  92 int max_fd = 0;
  93
  94 /* pid of shell == parent of agent */
  95 pid_t parent_pid = -1;
  96
  97 /* pathname and directory for AUTH_SOCKET */
  98 char socket_name[1024];
  99 char socket_dir[1024];
 100
 101 /* locking */
 102 int locked = 0;
 103 char *lock_passwd = NULL;
 104
 105 #ifdef HAVE___PROGNAME
 106 extern char *__progname;
 107 #else
 108 char *__progname;
 109 #endif
 110
 111 static void
 112 close_socket(SocketEntry *e)
 113 {
 114         close(e->fd);
 115         e->fd = -1;
 116         e->type = AUTH_UNUSED;
 117         buffer_free(&e->input);
 118         buffer_free(&e->output);
 119         buffer_free(&e->request);
 120 }
 121
 122 static void
 123 idtab_init(void)
 124 {
 125         int i;
 126
 127         for (i = 0; i <=2; i++) {
 128                 TAILQ_INIT(&idtable[i].idlist);
 129                 idtable[i].nentries = 0;
 130         }
 131 }
 132
 133 /* return private key table for requested protocol version */
 134 static Idtab *
 135 idtab_lookup(int version)
 136 {
 137         if (version < 1 || version > 2)
 138                 fatal("internal error, bad protocol version %d", version);
 139         return &idtable[version];
 140 }
 141
 142 static void
 143 free_identity(Identity *id)
 144 {
 145         key_free(id->key);
 146         xfree(id->comment);
 147         xfree(id);
 148 }
 149
 150 /* return matching private key for given public key */
 151 static Identity *
 152 lookup_identity(Key *key, int version)
 153 {
 154         Identity *id;
 155
 156         Idtab *tab = idtab_lookup(version);
 157         TAILQ_FOREACH(id, &tab->idlist, next) {
 158                 if (key_equal(key, id->key))
 159                         return (id);
 160         }
 161         return (NULL);
 162 }
 163
 164 /* send list of supported public keys to 'client' */
 165 static void
 166 process_request_identities(SocketEntry *e, int version)
 167 {
 168         Idtab *tab = idtab_lookup(version);
 169         Identity *id;
 170         Buffer msg;
 171
 172         buffer_init(&msg);
 173         buffer_put_char(&msg, (version == 1) ?
 174             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 175         buffer_put_int(&msg, tab->nentries);
 176         TAILQ_FOREACH(id, &tab->idlist, next) {
 177                 if (id->key->type == KEY_RSA1) {
 178                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 179                         buffer_put_bignum(&msg, id->key->rsa->e);
 180                         buffer_put_bignum(&msg, id->key->rsa->n);
 181                 } else {
 182                         u_char *blob;
 183                         u_int blen;
 184                         key_to_blob(id->key, &blob, &blen);
 185                         buffer_put_string(&msg, blob, blen);
 186                         xfree(blob);
 187                 }
 188                 buffer_put_cstring(&msg, id->comment);
 189         }
 190         buffer_put_int(&e->output, buffer_len(&msg));
 191         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 192         buffer_free(&msg);
 193 }
 194
 195 /* ssh1 only */
 196 static void
 197 process_authentication_challenge1(SocketEntry *e)
 198 {
 199         u_char buf[32], mdbuf[16], session_id[16];
 200         u_int response_type;
 201         BIGNUM *challenge;
 202         Identity *id;
 203         int i, len;
 204         Buffer msg;
 205         MD5_CTX md;
 206         Key *key;
 207
 208         buffer_init(&msg);
 209         key = key_new(KEY_RSA1);
 210         if ((challenge = BN_new()) == NULL)
 211                 fatal("process_authentication_challenge1: BN_new failed");
 212
 213         (void) buffer_get_int(&e->request);                     /* ignored */
 214         buffer_get_bignum(&e->request, key->rsa->e);
 215         buffer_get_bignum(&e->request, key->rsa->n);
 216         buffer_get_bignum(&e->request, challenge);
 217
 218         /* Only protocol 1.1 is supported */
 219         if (buffer_len(&e->request) == 0)
 220                 goto failure;
 221         buffer_get(&e->request, session_id, 16);
 222         response_type = buffer_get_int(&e->request);
 223         if (response_type != 1)
 224                 goto failure;
 225
 226         id = lookup_identity(key, 1);
 227         if (id != NULL) {
 228                 Key *private = id->key;
 229                 /* Decrypt the challenge using the private key. */
 230                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 231                         goto failure;
 232
 233                 /* The response is MD5 of decrypted challenge plus session id. */
 234                 len = BN_num_bytes(challenge);
 235                 if (len <= 0 || len > 32) {
 236                         log("process_authentication_challenge: bad challenge length %d", len);
 237                         goto failure;
 238                 }
 239                 memset(buf, 0, 32);
 240                 BN_bn2bin(challenge, buf + 32 - len);
 241                 MD5_Init(&md);
 242                 MD5_Update(&md, buf, 32);
 243                 MD5_Update(&md, session_id, 16);
 244                 MD5_Final(mdbuf, &md);
 245
 246                 /* Send the response. */
 247                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 248                 for (i = 0; i < 16; i++)
 249                         buffer_put_char(&msg, mdbuf[i]);
 250                 goto send;
 251         }
 252
 253 failure:
 254         /* Unknown identity or protocol error.  Send failure. */
 255         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 256 send:
 257         buffer_put_int(&e->output, buffer_len(&msg));
 258         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 259         key_free(key);
 260         BN_clear_free(challenge);
 261         buffer_free(&msg);
 262 }
 263
 264 /* ssh2 only */
 265 static void
 266 process_sign_request2(SocketEntry *e)
 267 {
 268         u_char *blob, *data, *signature = NULL;
 269         u_int blen, dlen, slen = 0;
 270         extern int datafellows;
 271         int ok = -1, flags;
 272         Buffer msg;
 273         Key *key;
 274
 275         datafellows = 0;
 276
 277         blob = buffer_get_string(&e->request, &blen);
 278         data = buffer_get_string(&e->request, &dlen);
 279
 280         flags = buffer_get_int(&e->request);
 281         if (flags & SSH_AGENT_OLD_SIGNATURE)
 282                 datafellows = SSH_BUG_SIGBLOB;
 283
 284         key = key_from_blob(blob, blen);
 285         if (key != NULL) {
 286                 Identity *id = lookup_identity(key, 2);
 287                 if (id != NULL)
 288                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 289         }
 290         key_free(key);
 291         buffer_init(&msg);
 292         if (ok == 0) {
 293                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 294                 buffer_put_string(&msg, signature, slen);
 295         } else {
 296                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 297         }
 298         buffer_put_int(&e->output, buffer_len(&msg));
 299         buffer_append(&e->output, buffer_ptr(&msg),
 300             buffer_len(&msg));
 301         buffer_free(&msg);
 302         xfree(data);
 303         xfree(blob);
 304         if (signature != NULL)
 305                 xfree(signature);
 306 }
 307
 308 /* shared */
 309 static void
 310 process_remove_identity(SocketEntry *e, int version)
 311 {
 312         u_int blen, bits;
 313         int success = 0;
 314         Key *key = NULL;
 315         u_char *blob;
 316
 317         switch (version) {
 318         case 1:
 319                 key = key_new(KEY_RSA1);
 320                 bits = buffer_get_int(&e->request);
 321                 buffer_get_bignum(&e->request, key->rsa->e);
 322                 buffer_get_bignum(&e->request, key->rsa->n);
 323
 324                 if (bits != key_size(key))
 325                         log("Warning: identity keysize mismatch: actual %u, announced %u",
 326                             key_size(key), bits);
 327                 break;
 328         case 2:
 329                 blob = buffer_get_string(&e->request, &blen);
 330                 key = key_from_blob(blob, blen);
 331                 xfree(blob);
 332                 break;
 333         }
 334         if (key != NULL) {
 335                 Identity *id = lookup_identity(key, version);
 336                 if (id != NULL) {
 337                         /*
 338                          * We have this key.  Free the old key.  Since we
 339                          * don\'t want to leave empty slots in the middle of
 340                          * the array, we actually free the key there and move
 341                          * all the entries between the empty slot and the end
 342                          * of the array.
 343                          */
 344                         Idtab *tab = idtab_lookup(version);
 345                         if (tab->nentries < 1)
 346                                 fatal("process_remove_identity: "
 347                                     "internal error: tab->nentries %d",
 348                                     tab->nentries);
 349                         TAILQ_REMOVE(&tab->idlist, id, next);
 350                         free_identity(id);
 351                         tab->nentries--;
 352                         success = 1;
 353                 }
 354                 key_free(key);
 355         }
 356         buffer_put_int(&e->output, 1);
 357         buffer_put_char(&e->output,
 358             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 359 }
 360
 361 static void
 362 process_remove_all_identities(SocketEntry *e, int version)
 363 {
 364         Idtab *tab = idtab_lookup(version);
 365         Identity *id;
 366
 367         /* Loop over all identities and clear the keys. */
 368         for (id = TAILQ_FIRST(&tab->idlist); id;
 369             id = TAILQ_FIRST(&tab->idlist)) {
 370                 TAILQ_REMOVE(&tab->idlist, id, next);
 371                 free_identity(id);
 372         }
 373
 374         /* Mark that there are no identities. */
 375         tab->nentries = 0;
 376
 377         /* Send success. */
 378         buffer_put_int(&e->output, 1);
 379         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 380 }
 381
 382 static void
 383 reaper(void)
 384 {
 385         u_int now = time(NULL);
 386         Identity *id, *nxt;
 387         int version;
 388         Idtab *tab;
 389
 390         for (version = 1; version < 3; version++) {
 391                 tab = idtab_lookup(version);
 392                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 393                         nxt = TAILQ_NEXT(id, next);
 394                         if (id->death != 0 && now >= id->death) {
 395                                 TAILQ_REMOVE(&tab->idlist, id, next);
 396                                 free_identity(id);
 397                                 tab->nentries--;
 398                         }
 399                 }
 400         }
 401 }
 402
 403 static void
 404 process_add_identity(SocketEntry *e, int version)
 405 {
 406         Idtab *tab = idtab_lookup(version);
 407         int type, success = 0, death = 0;
 408         char *type_name, *comment;
 409         Key *k = NULL;
 410
 411         switch (version) {
 412         case 1:
 413                 k = key_new_private(KEY_RSA1);
 414                 (void) buffer_get_int(&e->request);             /* ignored */
 415                 buffer_get_bignum(&e->request, k->rsa->n);
 416                 buffer_get_bignum(&e->request, k->rsa->e);
 417                 buffer_get_bignum(&e->request, k->rsa->d);
 418                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 419
 420                 /* SSH and SSL have p and q swapped */
 421                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 422                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 423
 424                 /* Generate additional parameters */
 425                 rsa_generate_additional_parameters(k->rsa);
 426                 break;
 427         case 2:
 428                 type_name = buffer_get_string(&e->request, NULL);
 429                 type = key_type_from_name(type_name);
 430                 xfree(type_name);
 431                 switch (type) {
 432                 case KEY_DSA:
 433                         k = key_new_private(type);
 434                         buffer_get_bignum2(&e->request, k->dsa->p);
 435                         buffer_get_bignum2(&e->request, k->dsa->q);
 436                         buffer_get_bignum2(&e->request, k->dsa->g);
 437                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 438                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 439                         break;
 440                 case KEY_RSA:
 441                         k = key_new_private(type);
 442                         buffer_get_bignum2(&e->request, k->rsa->n);
 443                         buffer_get_bignum2(&e->request, k->rsa->e);
 444                         buffer_get_bignum2(&e->request, k->rsa->d);
 445                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 446                         buffer_get_bignum2(&e->request, k->rsa->p);
 447                         buffer_get_bignum2(&e->request, k->rsa->q);
 448
 449                         /* Generate additional parameters */
 450                         rsa_generate_additional_parameters(k->rsa);
 451                         break;
 452                 default:
 453                         buffer_clear(&e->request);
 454                         goto send;
 455                 }
 456                 break;
 457         }
 458         comment = buffer_get_string(&e->request, NULL);
 459         if (k == NULL) {
 460                 xfree(comment);
 461                 goto send;
 462         }
 463         success = 1;
 464         while (buffer_len(&e->request)) {
 465                 switch (buffer_get_char(&e->request)) {
 466                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 467                         death = time(NULL) + buffer_get_int(&e->request);
 468                         break;
 469                 default:
 470                         break;
 471                 }
 472         }
 473         if (lookup_identity(k, version) == NULL) {
 474                 Identity *id = xmalloc(sizeof(Identity));
 475                 id->key = k;
 476                 id->comment = comment;
 477                 id->death = death;
 478                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 479                 /* Increment the number of identities. */
 480                 tab->nentries++;
 481         } else {
 482                 key_free(k);
 483                 xfree(comment);
 484         }
 485 send:
 486         buffer_put_int(&e->output, 1);
 487         buffer_put_char(&e->output,
 488             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 489 }
 490
 491 /* XXX todo: encrypt sensitive data with passphrase */
 492 static void
 493 process_lock_agent(SocketEntry *e, int lock)
 494 {
 495         int success = 0;
 496         char *passwd;
 497
 498         passwd = buffer_get_string(&e->request, NULL);
 499         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 500                 locked = 0;
 501                 memset(lock_passwd, 0, strlen(lock_passwd));
 502                 xfree(lock_passwd);
 503                 lock_passwd = NULL;
 504                 success = 1;
 505         } else if (!locked && lock) {
 506                 locked = 1;
 507                 lock_passwd = xstrdup(passwd);
 508                 success = 1;
 509         }
 510         memset(passwd, 0, strlen(passwd));
 511         xfree(passwd);
 512
 513         buffer_put_int(&e->output, 1);
 514         buffer_put_char(&e->output,
 515             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 516 }
 517
 518 static void
 519 no_identities(SocketEntry *e, u_int type)
 520 {
 521         Buffer msg;
 522
 523         buffer_init(&msg);
 524         buffer_put_char(&msg,
 525             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 526             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 527         buffer_put_int(&msg, 0);
 528         buffer_put_int(&e->output, buffer_len(&msg));
 529         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 530         buffer_free(&msg);
 531 }
 532
 533 #ifdef SMARTCARD
 534 static void
 535 process_add_smartcard_key (SocketEntry *e)
 536 {
 537         char *sc_reader_id = NULL, *pin;
 538         int i, version, success = 0;
 539         Key **keys, *k;
 540         Identity *id;
 541         Idtab *tab;
 542
 543         sc_reader_id = buffer_get_string(&e->request, NULL);
 544         pin = buffer_get_string(&e->request, NULL);
 545         keys = sc_get_keys(sc_reader_id, pin);
 546         xfree(sc_reader_id);
 547         xfree(pin);
 548
 549         if (keys == NULL || keys[0] == NULL) {
 550                 error("sc_get_keys failed");
 551                 goto send;
 552         }
 553         for (i = 0; keys[i] != NULL; i++) {
 554                 k = keys[i];
 555                 version = k->type == KEY_RSA1 ? 1 : 2;
 556                 tab = idtab_lookup(version);
 557                 if (lookup_identity(k, version) == NULL) {
 558                         id = xmalloc(sizeof(Identity));
 559                         id->key = k;
 560                         id->comment = xstrdup("smartcard key");
 561                         id->death = 0;
 562                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 563                         tab->nentries++;
 564                         success = 1;
 565                 } else {
 566                         key_free(k);
 567                 }
 568                 keys[i] = NULL;
 569         }
 570         xfree(keys);
 571 send:
 572         buffer_put_int(&e->output, 1);
 573         buffer_put_char(&e->output,
 574             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 575 }
 576
 577 static void
 578 process_remove_smartcard_key(SocketEntry *e)
 579 {
 580         char *sc_reader_id = NULL, *pin;
 581         int i, version, success = 0;
 582         Key **keys, *k = NULL;
 583         Identity *id;
 584         Idtab *tab;
 585
 586         sc_reader_id = buffer_get_string(&e->request, NULL);
 587         pin = buffer_get_string(&e->request, NULL);
 588         keys = sc_get_keys(sc_reader_id, pin);
 589         xfree(sc_reader_id);
 590         xfree(pin);
 591
 592         if (keys == NULL || keys[0] == NULL) {
 593                 error("sc_get_keys failed");
 594                 goto send;
 595         }
 596         for (i = 0; keys[i] != NULL; i++) {
 597                 k = keys[i];
 598                 version = k->type == KEY_RSA1 ? 1 : 2;
 599                 if ((id = lookup_identity(k, version)) != NULL) {
 600                         tab = idtab_lookup(version);
 601                         TAILQ_REMOVE(&tab->idlist, id, next);
 602                         tab->nentries--;
 603                         free_identity(id);
 604                         success = 1;
 605                 }
 606                 key_free(k);
 607                 keys[i] = NULL;
 608         }
 609         xfree(keys);
 610 send:
 611         buffer_put_int(&e->output, 1);
 612         buffer_put_char(&e->output,
 613             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 614 }
 615 #endif /* SMARTCARD */
 616
 617 /* dispatch incoming messages */
 618
 619 static void
 620 process_message(SocketEntry *e)
 621 {
 622         u_int msg_len, type;
 623         u_char *cp;
 624
 625         /* kill dead keys */
 626         reaper();
 627
 628         if (buffer_len(&e->input) < 5)
 629                 return;         /* Incomplete message. */
 630         cp = buffer_ptr(&e->input);
 631         msg_len = GET_32BIT(cp);
 632         if (msg_len > 256 * 1024) {
 633                 close_socket(e);
 634                 return;
 635         }
 636         if (buffer_len(&e->input) < msg_len + 4)
 637                 return;
 638
 639         /* move the current input to e->request */
 640         buffer_consume(&e->input, 4);
 641         buffer_clear(&e->request);
 642         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 643         buffer_consume(&e->input, msg_len);
 644         type = buffer_get_char(&e->request);
 645
 646         /* check wheter agent is locked */
 647         if (locked && type != SSH_AGENTC_UNLOCK) {
 648                 buffer_clear(&e->request);
 649                 switch (type) {
 650                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 651                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 652                         /* send empty lists */
 653                         no_identities(e, type);
 654                         break;
 655                 default:
 656                         /* send a fail message for all other request types */
 657                         buffer_put_int(&e->output, 1);
 658                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 659                 }
 660                 return;
 661         }
 662
 663         debug("type %d", type);
 664         switch (type) {
 665         case SSH_AGENTC_LOCK:
 666         case SSH_AGENTC_UNLOCK:
 667                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 668                 break;
 669         /* ssh1 */
 670         case SSH_AGENTC_RSA_CHALLENGE:
 671                 process_authentication_challenge1(e);
 672                 break;
 673         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 674                 process_request_identities(e, 1);
 675                 break;
 676         case SSH_AGENTC_ADD_RSA_IDENTITY:
 677         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 678                 process_add_identity(e, 1);
 679                 break;
 680         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 681                 process_remove_identity(e, 1);
 682                 break;
 683         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 684                 process_remove_all_identities(e, 1);
 685                 break;
 686         /* ssh2 */
 687         case SSH2_AGENTC_SIGN_REQUEST:
 688                 process_sign_request2(e);
 689                 break;
 690         case SSH2_AGENTC_REQUEST_IDENTITIES:
 691                 process_request_identities(e, 2);
 692                 break;
 693         case SSH2_AGENTC_ADD_IDENTITY:
 694         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 695                 process_add_identity(e, 2);
 696                 break;
 697         case SSH2_AGENTC_REMOVE_IDENTITY:
 698                 process_remove_identity(e, 2);
 699                 break;
 700         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 701                 process_remove_all_identities(e, 2);
 702                 break;
 703 #ifdef SMARTCARD
 704         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 705                 process_add_smartcard_key(e);
 706                 break;
 707         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 708                 process_remove_smartcard_key(e);
 709                 break;
 710 #endif /* SMARTCARD */
 711         default:
 712                 /* Unknown message.  Respond with failure. */
 713                 error("Unknown message %d", type);
 714                 buffer_clear(&e->request);
 715                 buffer_put_int(&e->output, 1);
 716                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 717                 break;
 718         }
 719 }
 720
 721 static void
 722 new_socket(sock_type type, int fd)
 723 {
 724         u_int i, old_alloc;
 725
 726         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 727                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 728
 729         if (fd > max_fd)
 730                 max_fd = fd;
 731
 732         for (i = 0; i < sockets_alloc; i++)
 733                 if (sockets[i].type == AUTH_UNUSED) {
 734                         sockets[i].fd = fd;
 735                         sockets[i].type = type;
 736                         buffer_init(&sockets[i].input);
 737                         buffer_init(&sockets[i].output);
 738                         buffer_init(&sockets[i].request);
 739                         return;
 740                 }
 741         old_alloc = sockets_alloc;
 742         sockets_alloc += 10;
 743         if (sockets)
 744                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 745         else
 746                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 747         for (i = old_alloc; i < sockets_alloc; i++)
 748                 sockets[i].type = AUTH_UNUSED;
 749         sockets[old_alloc].type = type;
 750         sockets[old_alloc].fd = fd;
 751         buffer_init(&sockets[old_alloc].input);
 752         buffer_init(&sockets[old_alloc].output);
 753         buffer_init(&sockets[old_alloc].request);
 754 }
 755
 756 static int
 757 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 758 {
 759         u_int i, sz;
 760         int n = 0;
 761
 762         for (i = 0; i < sockets_alloc; i++) {
 763                 switch (sockets[i].type) {
 764                 case AUTH_SOCKET:
 765                 case AUTH_CONNECTION:
 766                         n = MAX(n, sockets[i].fd);
 767                         break;
 768                 case AUTH_UNUSED:
 769                         break;
 770                 default:
 771                         fatal("Unknown socket type %d", sockets[i].type);
 772                         break;
 773                 }
 774         }
 775
 776         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 777         if (*fdrp == NULL || sz > *nallocp) {
 778                 if (*fdrp)
 779                         xfree(*fdrp);
 780                 if (*fdwp)
 781                         xfree(*fdwp);
 782                 *fdrp = xmalloc(sz);
 783                 *fdwp = xmalloc(sz);
 784                 *nallocp = sz;
 785         }
 786         if (n < *fdl)
 787                 debug("XXX shrink: %d < %d", n, *fdl);
 788         *fdl = n;
 789         memset(*fdrp, 0, sz);
 790         memset(*fdwp, 0, sz);
 791
 792         for (i = 0; i < sockets_alloc; i++) {
 793                 switch (sockets[i].type) {
 794                 case AUTH_SOCKET:
 795                 case AUTH_CONNECTION:
 796                         FD_SET(sockets[i].fd, *fdrp);
 797                         if (buffer_len(&sockets[i].output) > 0)
 798                                 FD_SET(sockets[i].fd, *fdwp);
 799                         break;
 800                 default:
 801                         break;
 802                 }
 803         }
 804         return (1);
 805 }
 806
 807 static void
 808 after_select(fd_set *readset, fd_set *writeset)
 809 {
 810         struct sockaddr_un sunaddr;
 811         socklen_t slen;
 812         char buf[1024];
 813         int len, sock;
 814         u_int i;
 815         uid_t euid;
 816         gid_t egid;
 817
 818         for (i = 0; i < sockets_alloc; i++)
 819                 switch (sockets[i].type) {
 820                 case AUTH_UNUSED:
 821                         break;
 822                 case AUTH_SOCKET:
 823                         if (FD_ISSET(sockets[i].fd, readset)) {
 824                                 slen = sizeof(sunaddr);
 825                                 sock = accept(sockets[i].fd,
 826                                     (struct sockaddr *) &sunaddr, &slen);
 827                                 if (sock < 0) {
 828                                         error("accept from AUTH_SOCKET: %s",
 829                                             strerror(errno));
 830                                         break;
 831                                 }
 832                                 if (getpeereid(sock, &euid, &egid) < 0) {
 833                                         error("getpeereid %d failed: %s",
 834                                             sock, strerror(errno));
 835                                         close(sock);
 836                                         break;
 837                                 }
 838                                 if ((euid != 0) && (getuid() != euid)) {
 839                                         error("uid mismatch: "
 840                                             "peer euid %u != uid %u",
 841                                             (u_int) euid, (u_int) getuid());
 842                                         close(sock);
 843                                         break;
 844                                 }
 845                                 new_socket(AUTH_CONNECTION, sock);
 846                         }
 847                         break;
 848                 case AUTH_CONNECTION:
 849                         if (buffer_len(&sockets[i].output) > 0 &&
 850                             FD_ISSET(sockets[i].fd, writeset)) {
 851                                 do {
 852                                         len = write(sockets[i].fd,
 853                                             buffer_ptr(&sockets[i].output),
 854                                             buffer_len(&sockets[i].output));
 855                                         if (len == -1 && (errno == EAGAIN ||
 856                                             errno == EINTR))
 857                                                 continue;
 858                                         break;
 859                                 } while (1);
 860                                 if (len <= 0) {
 861                                         close_socket(&sockets[i]);
 862                                         break;
 863                                 }
 864                                 buffer_consume(&sockets[i].output, len);
 865                         }
 866                         if (FD_ISSET(sockets[i].fd, readset)) {
 867                                 do {
 868                                         len = read(sockets[i].fd, buf, sizeof(buf));
 869                                         if (len == -1 && (errno == EAGAIN ||
 870                                             errno == EINTR))
 871                                                 continue;
 872                                         break;
 873                                 } while (1);
 874                                 if (len <= 0) {
 875                                         close_socket(&sockets[i]);
 876                                         break;
 877                                 }
 878                                 buffer_append(&sockets[i].input, buf, len);
 879                                 process_message(&sockets[i]);
 880                         }
 881                         break;
 882                 default:
 883                         fatal("Unknown type %d", sockets[i].type);
 884                 }
 885 }
 886
 887 static void
 888 cleanup_socket(void *p)
 889 {
 890         if (socket_name[0])
 891                 unlink(socket_name);
 892         if (socket_dir[0])
 893                 rmdir(socket_dir);
 894 }
 895
 896 static void
 897 cleanup_exit(int i)
 898 {
 899         cleanup_socket(NULL);
 900         exit(i);
 901 }
 902
 903 static void
 904 cleanup_handler(int sig)
 905 {
 906         cleanup_socket(NULL);
 907         _exit(2);
 908 }
 909
 910 static void
 911 check_parent_exists(int sig)
 912 {
 913         int save_errno = errno;
 914
 915         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 916                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 917                 cleanup_handler(sig); /* safe */
 918         }
 919         signal(SIGALRM, check_parent_exists);
 920         alarm(10);
 921         errno = save_errno;
 922 }
 923
 924 static void
 925 usage(void)
 926 {
 927         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 928             __progname);
 929         fprintf(stderr, "Options:\n");
 930         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 931         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 932         fprintf(stderr, "  -k          Kill the current agent.\n");
 933         fprintf(stderr, "  -d          Debug mode.\n");
 934         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 935         exit(1);
 936 }
 937
 938 int
 939 main(int ac, char **av)
 940 {
 941         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 942         char *shell, *format, *pidstr, *agentsocket = NULL;
 943         fd_set *readsetp = NULL, *writesetp = NULL;
 944         struct sockaddr_un sunaddr;
 945 #ifdef HAVE_SETRLIMIT
 946         struct rlimit rlim;
 947 #endif
 948 #ifdef HAVE_CYGWIN
 949         int prev_mask;
 950 #endif
 951         extern int optind;
 952         extern char *optarg;
 953         pid_t pid;
 954         char pidstrbuf[1 + 3 * sizeof pid];
 955
 956         /* drop */
 957         setegid(getgid());
 958         setgid(getgid());
 959         setuid(geteuid());
 960
 961         SSLeay_add_all_algorithms();
 962
 963         __progname = get_progname(av[0]);
 964         init_rng();
 965         seed_rng();
 966
 967         while ((ch = getopt(ac, av, "cdksa:")) != -1) {
 968                 switch (ch) {
 969                 case 'c':
 970                         if (s_flag)
 971                                 usage();
 972                         c_flag++;
 973                         break;
 974                 case 'k':
 975                         k_flag++;
 976                         break;
 977                 case 's':
 978                         if (c_flag)
 979                                 usage();
 980                         s_flag++;
 981                         break;
 982                 case 'd':
 983                         if (d_flag)
 984                                 usage();
 985                         d_flag++;
 986                         break;
 987                 case 'a':
 988                         agentsocket = optarg;
 989                         break;
 990                 default:
 991                         usage();
 992                 }
 993         }
 994         ac -= optind;
 995         av += optind;
 996
 997         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
 998                 usage();
 999
1000         if (ac == 0 && !c_flag && !s_flag) {
1001                 shell = getenv("SHELL");
1002                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1003                         c_flag = 1;
1004         }
1005         if (k_flag) {
1006                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1007                 if (pidstr == NULL) {
1008                         fprintf(stderr, "%s not set, cannot kill agent\n",
1009                             SSH_AGENTPID_ENV_NAME);
1010                         exit(1);
1011                 }
1012                 pid = atoi(pidstr);
1013                 if (pid < 1) {
1014                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
1015                             SSH_AGENTPID_ENV_NAME, pidstr);
1016                         exit(1);
1017                 }
1018                 if (kill(pid, SIGTERM) == -1) {
1019                         perror("kill");
1020                         exit(1);
1021                 }
1022                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1023                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1024                 printf(format, SSH_AGENTPID_ENV_NAME);
1025                 printf("echo Agent pid %ld killed;\n", (long)pid);
1026                 exit(0);
1027         }
1028         parent_pid = getpid();
1029
1030         if (agentsocket == NULL) {
1031                 /* Create private directory for agent socket */
1032                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
1033                 if (mkdtemp(socket_dir) == NULL) {
1034                         perror("mkdtemp: private socket dir");
1035                         exit(1);
1036                 }
1037                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1038                     (long)parent_pid);
1039         } else {
1040                 /* Try to use specified agent socket */
1041                 socket_dir[0] = '\0';
1042                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1043         }
1044
1045         /*
1046          * Create socket early so it will exist before command gets run from
1047          * the parent.
1048          */
1049         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1050         if (sock < 0) {
1051                 perror("socket");
1052                 cleanup_exit(1);
1053         }
1054         memset(&sunaddr, 0, sizeof(sunaddr));
1055         sunaddr.sun_family = AF_UNIX;
1056         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1057 #ifdef HAVE_CYGWIN
1058         prev_mask = umask(0177);
1059 #endif
1060         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1061                 perror("bind");
1062 #ifdef HAVE_CYGWIN
1063                 umask(prev_mask);
1064 #endif
1065                 cleanup_exit(1);
1066         }
1067 #ifdef HAVE_CYGWIN
1068         umask(prev_mask);
1069 #endif
1070         if (listen(sock, 128) < 0) {
1071                 perror("listen");
1072                 cleanup_exit(1);
1073         }
1074
1075         /*
1076          * Fork, and have the parent execute the command, if any, or present
1077          * the socket data.  The child continues as the authentication agent.
1078          */
1079         if (d_flag) {
1080                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1081                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1082                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1083                     SSH_AUTHSOCKET_ENV_NAME);
1084                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1085                 goto skip;
1086         }
1087         pid = fork();
1088         if (pid == -1) {
1089                 perror("fork");
1090                 cleanup_exit(1);
1091         }
1092         if (pid != 0) {         /* Parent - execute the given command. */
1093                 close(sock);
1094                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1095                 if (ac == 0) {
1096                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1097                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1098                             SSH_AUTHSOCKET_ENV_NAME);
1099                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1100                             SSH_AGENTPID_ENV_NAME);
1101                         printf("echo Agent pid %ld;\n", (long)pid);
1102                         exit(0);
1103                 }
1104                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1105                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1106                         perror("setenv");
1107                         exit(1);
1108                 }
1109                 execvp(av[0], av);
1110                 perror(av[0]);
1111                 exit(1);
1112         }
1113         /* child */
1114         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1115
1116         if (setsid() == -1) {
1117                 error("setsid: %s", strerror(errno));
1118                 cleanup_exit(1);
1119         }
1120
1121         (void)chdir("/");
1122         close(0);
1123         close(1);
1124         close(2);
1125
1126 #ifdef HAVE_SETRLIMIT
1127         /* deny core dumps, since memory contains unencrypted private keys */
1128         rlim.rlim_cur = rlim.rlim_max = 0;
1129         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1130                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1131                 cleanup_exit(1);
1132         }
1133 #endif
1134
1135 skip:
1136         fatal_add_cleanup(cleanup_socket, NULL);
1137         new_socket(AUTH_SOCKET, sock);
1138         if (ac > 0) {
1139                 signal(SIGALRM, check_parent_exists);
1140                 alarm(10);
1141         }
1142         idtab_init();
1143         if (!d_flag)
1144                 signal(SIGINT, SIG_IGN);
1145         signal(SIGPIPE, SIG_IGN);
1146         signal(SIGHUP, cleanup_handler);
1147         signal(SIGTERM, cleanup_handler);
1148         nalloc = 0;
1149
1150         while (1) {
1151                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1152                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1153                         if (errno == EINTR)
1154                                 continue;
1155                         fatal("select: %s", strerror(errno));
1156                 }
1157                 after_select(readsetp, writesetp);
1158         }
1159         /* NOTREACHED */
1160 }