crypto/openssh-5/ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.157 2007/09/25 23:48:57 canacar Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * The authentication agent program.
   7  *
   8  * As far as I am concerned, the code I have written for this software
   9  * can be used freely for any purpose.  Any derived versions of this
  10  * software must be clearly marked as such, and if the derived work is
  11  * incompatible with the protocol description in the RFC file, it must be
  12  * called by a name other than "ssh" or "Secure Shell".
  13  *
  14  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  15  *
  16  * Redistribution and use in source and binary forms, with or without
  17  * modification, are permitted provided that the following conditions
  18  * are met:
  19  * 1. Redistributions of source code must retain the above copyright
  20  *    notice, this list of conditions and the following disclaimer.
  21  * 2. Redistributions in binary form must reproduce the above copyright
  22  *    notice, this list of conditions and the following disclaimer in the
  23  *    documentation and/or other materials provided with the distribution.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  26  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  27  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  28  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  29  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  30  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  31  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  32  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  33  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  34  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  35  */
  36
  37 #include "includes.h"
  38
  39 #include <sys/types.h>
  40 #include <sys/param.h>
  41 #include <sys/resource.h>
  42 #include <sys/stat.h>
  43 #include <sys/socket.h>
  44 #ifdef HAVE_SYS_TIME_H
  45 # include <sys/time.h>
  46 #endif
  47 #ifdef HAVE_SYS_UN_H
  48 # include <sys/un.h>
  49 #endif
  50 #include "openbsd-compat/sys-queue.h"
  51
  52 #include <openssl/evp.h>
  53 #include <openssl/md5.h>
  54 #include "openbsd-compat/openssl-compat.h"
  55
  56 #include <errno.h>
  57 #include <fcntl.h>
  58 #ifdef HAVE_PATHS_H
  59 # include <paths.h>
  60 #endif
  61 #include <signal.h>
  62 #include <stdarg.h>
  63 #include <stdio.h>
  64 #include <stdlib.h>
  65 #include <time.h>
  66 #include <string.h>
  67 #include <unistd.h>
  68
  69 #include "xmalloc.h"
  70 #include "ssh.h"
  71 #include "rsa.h"
  72 #include "buffer.h"
  73 #include "key.h"
  74 #include "authfd.h"
  75 #include "compat.h"
  76 #include "log.h"
  77 #include "misc.h"
  78
  79 #ifdef SMARTCARD
  80 #include "scard.h"
  81 #endif
  82
  83 #if defined(HAVE_SYS_PRCTL_H)
  84 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  85 #endif
  86
  87 typedef enum {
  88         AUTH_UNUSED,
  89         AUTH_SOCKET,
  90         AUTH_CONNECTION
  91 } sock_type;
  92
  93 typedef struct {
  94         int fd;
  95         sock_type type;
  96         Buffer input;
  97         Buffer output;
  98         Buffer request;
  99 } SocketEntry;
 100
 101 u_int sockets_alloc = 0;
 102 SocketEntry *sockets = NULL;
 103
 104 typedef struct identity {
 105         TAILQ_ENTRY(identity) next;
 106         Key *key;
 107         char *comment;
 108         u_int death;
 109         u_int confirm;
 110 } Identity;
 111
 112 typedef struct {
 113         int nentries;
 114         TAILQ_HEAD(idqueue, identity) idlist;
 115 } Idtab;
 116
 117 /* private key table, one per protocol version */
 118 Idtab idtable[3];
 119
 120 int max_fd = 0;
 121
 122 /* pid of shell == parent of agent */
 123 pid_t parent_pid = -1;
 124 u_int parent_alive_interval = 0;
 125
 126 /* pathname and directory for AUTH_SOCKET */
 127 char socket_name[MAXPATHLEN];
 128 char socket_dir[MAXPATHLEN];
 129
 130 /* locking */
 131 int locked = 0;
 132 char *lock_passwd = NULL;
 133
 134 extern char *__progname;
 135
 136 /* Default lifetime (0 == forever) */
 137 static int lifetime = 0;
 138
 139 static void
 140 close_socket(SocketEntry *e)
 141 {
 142         close(e->fd);
 143         e->fd = -1;
 144         e->type = AUTH_UNUSED;
 145         buffer_free(&e->input);
 146         buffer_free(&e->output);
 147         buffer_free(&e->request);
 148 }
 149
 150 static void
 151 idtab_init(void)
 152 {
 153         int i;
 154
 155         for (i = 0; i <=2; i++) {
 156                 TAILQ_INIT(&idtable[i].idlist);
 157                 idtable[i].nentries = 0;
 158         }
 159 }
 160
 161 /* return private key table for requested protocol version */
 162 static Idtab *
 163 idtab_lookup(int version)
 164 {
 165         if (version < 1 || version > 2)
 166                 fatal("internal error, bad protocol version %d", version);
 167         return &idtable[version];
 168 }
 169
 170 static void
 171 free_identity(Identity *id)
 172 {
 173         key_free(id->key);
 174         xfree(id->comment);
 175         xfree(id);
 176 }
 177
 178 /* return matching private key for given public key */
 179 static Identity *
 180 lookup_identity(Key *key, int version)
 181 {
 182         Identity *id;
 183
 184         Idtab *tab = idtab_lookup(version);
 185         TAILQ_FOREACH(id, &tab->idlist, next) {
 186                 if (key_equal(key, id->key))
 187                         return (id);
 188         }
 189         return (NULL);
 190 }
 191
 192 /* Check confirmation of keysign request */
 193 static int
 194 confirm_key(Identity *id)
 195 {
 196         char *p;
 197         int ret = -1;
 198
 199         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 200         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 201             id->comment, p))
 202                 ret = 0;
 203         xfree(p);
 204
 205         return (ret);
 206 }
 207
 208 /* send list of supported public keys to 'client' */
 209 static void
 210 process_request_identities(SocketEntry *e, int version)
 211 {
 212         Idtab *tab = idtab_lookup(version);
 213         Identity *id;
 214         Buffer msg;
 215
 216         buffer_init(&msg);
 217         buffer_put_char(&msg, (version == 1) ?
 218             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 219         buffer_put_int(&msg, tab->nentries);
 220         TAILQ_FOREACH(id, &tab->idlist, next) {
 221                 if (id->key->type == KEY_RSA1) {
 222                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 223                         buffer_put_bignum(&msg, id->key->rsa->e);
 224                         buffer_put_bignum(&msg, id->key->rsa->n);
 225                 } else {
 226                         u_char *blob;
 227                         u_int blen;
 228                         key_to_blob(id->key, &blob, &blen);
 229                         buffer_put_string(&msg, blob, blen);
 230                         xfree(blob);
 231                 }
 232                 buffer_put_cstring(&msg, id->comment);
 233         }
 234         buffer_put_int(&e->output, buffer_len(&msg));
 235         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 236         buffer_free(&msg);
 237 }
 238
 239 /* ssh1 only */
 240 static void
 241 process_authentication_challenge1(SocketEntry *e)
 242 {
 243         u_char buf[32], mdbuf[16], session_id[16];
 244         u_int response_type;
 245         BIGNUM *challenge;
 246         Identity *id;
 247         int i, len;
 248         Buffer msg;
 249         MD5_CTX md;
 250         Key *key;
 251
 252         buffer_init(&msg);
 253         key = key_new(KEY_RSA1);
 254         if ((challenge = BN_new()) == NULL)
 255                 fatal("process_authentication_challenge1: BN_new failed");
 256
 257         (void) buffer_get_int(&e->request);                     /* ignored */
 258         buffer_get_bignum(&e->request, key->rsa->e);
 259         buffer_get_bignum(&e->request, key->rsa->n);
 260         buffer_get_bignum(&e->request, challenge);
 261
 262         /* Only protocol 1.1 is supported */
 263         if (buffer_len(&e->request) == 0)
 264                 goto failure;
 265         buffer_get(&e->request, session_id, 16);
 266         response_type = buffer_get_int(&e->request);
 267         if (response_type != 1)
 268                 goto failure;
 269
 270         id = lookup_identity(key, 1);
 271         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 272                 Key *private = id->key;
 273                 /* Decrypt the challenge using the private key. */
 274                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 275                         goto failure;
 276
 277                 /* The response is MD5 of decrypted challenge plus session id. */
 278                 len = BN_num_bytes(challenge);
 279                 if (len <= 0 || len > 32) {
 280                         logit("process_authentication_challenge: bad challenge length %d", len);
 281                         goto failure;
 282                 }
 283                 memset(buf, 0, 32);
 284                 BN_bn2bin(challenge, buf + 32 - len);
 285                 MD5_Init(&md);
 286                 MD5_Update(&md, buf, 32);
 287                 MD5_Update(&md, session_id, 16);
 288                 MD5_Final(mdbuf, &md);
 289
 290                 /* Send the response. */
 291                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 292                 for (i = 0; i < 16; i++)
 293                         buffer_put_char(&msg, mdbuf[i]);
 294                 goto send;
 295         }
 296
 297 failure:
 298         /* Unknown identity or protocol error.  Send failure. */
 299         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 300 send:
 301         buffer_put_int(&e->output, buffer_len(&msg));
 302         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 303         key_free(key);
 304         BN_clear_free(challenge);
 305         buffer_free(&msg);
 306 }
 307
 308 /* ssh2 only */
 309 static void
 310 process_sign_request2(SocketEntry *e)
 311 {
 312         u_char *blob, *data, *signature = NULL;
 313         u_int blen, dlen, slen = 0;
 314         extern int datafellows;
 315         int ok = -1, flags;
 316         Buffer msg;
 317         Key *key;
 318
 319         datafellows = 0;
 320
 321         blob = buffer_get_string(&e->request, &blen);
 322         data = buffer_get_string(&e->request, &dlen);
 323
 324         flags = buffer_get_int(&e->request);
 325         if (flags & SSH_AGENT_OLD_SIGNATURE)
 326                 datafellows = SSH_BUG_SIGBLOB;
 327
 328         key = key_from_blob(blob, blen);
 329         if (key != NULL) {
 330                 Identity *id = lookup_identity(key, 2);
 331                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 332                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 333                 key_free(key);
 334         }
 335         buffer_init(&msg);
 336         if (ok == 0) {
 337                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 338                 buffer_put_string(&msg, signature, slen);
 339         } else {
 340                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 341         }
 342         buffer_put_int(&e->output, buffer_len(&msg));
 343         buffer_append(&e->output, buffer_ptr(&msg),
 344             buffer_len(&msg));
 345         buffer_free(&msg);
 346         xfree(data);
 347         xfree(blob);
 348         if (signature != NULL)
 349                 xfree(signature);
 350 }
 351
 352 /* shared */
 353 static void
 354 process_remove_identity(SocketEntry *e, int version)
 355 {
 356         u_int blen, bits;
 357         int success = 0;
 358         Key *key = NULL;
 359         u_char *blob;
 360
 361         switch (version) {
 362         case 1:
 363                 key = key_new(KEY_RSA1);
 364                 bits = buffer_get_int(&e->request);
 365                 buffer_get_bignum(&e->request, key->rsa->e);
 366                 buffer_get_bignum(&e->request, key->rsa->n);
 367
 368                 if (bits != key_size(key))
 369                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 370                             key_size(key), bits);
 371                 break;
 372         case 2:
 373                 blob = buffer_get_string(&e->request, &blen);
 374                 key = key_from_blob(blob, blen);
 375                 xfree(blob);
 376                 break;
 377         }
 378         if (key != NULL) {
 379                 Identity *id = lookup_identity(key, version);
 380                 if (id != NULL) {
 381                         /*
 382                          * We have this key.  Free the old key.  Since we
 383                          * don't want to leave empty slots in the middle of
 384                          * the array, we actually free the key there and move
 385                          * all the entries between the empty slot and the end
 386                          * of the array.
 387                          */
 388                         Idtab *tab = idtab_lookup(version);
 389                         if (tab->nentries < 1)
 390                                 fatal("process_remove_identity: "
 391                                     "internal error: tab->nentries %d",
 392                                     tab->nentries);
 393                         TAILQ_REMOVE(&tab->idlist, id, next);
 394                         free_identity(id);
 395                         tab->nentries--;
 396                         success = 1;
 397                 }
 398                 key_free(key);
 399         }
 400         buffer_put_int(&e->output, 1);
 401         buffer_put_char(&e->output,
 402             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 403 }
 404
 405 static void
 406 process_remove_all_identities(SocketEntry *e, int version)
 407 {
 408         Idtab *tab = idtab_lookup(version);
 409         Identity *id;
 410
 411         /* Loop over all identities and clear the keys. */
 412         for (id = TAILQ_FIRST(&tab->idlist); id;
 413             id = TAILQ_FIRST(&tab->idlist)) {
 414                 TAILQ_REMOVE(&tab->idlist, id, next);
 415                 free_identity(id);
 416         }
 417
 418         /* Mark that there are no identities. */
 419         tab->nentries = 0;
 420
 421         /* Send success. */
 422         buffer_put_int(&e->output, 1);
 423         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 424 }
 425
 426 /* removes expired keys and returns number of seconds until the next expiry */
 427 static u_int
 428 reaper(void)
 429 {
 430         u_int deadline = 0, now = time(NULL);
 431         Identity *id, *nxt;
 432         int version;
 433         Idtab *tab;
 434
 435         for (version = 1; version < 3; version++) {
 436                 tab = idtab_lookup(version);
 437                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 438                         nxt = TAILQ_NEXT(id, next);
 439                         if (id->death == 0)
 440                                 continue;
 441                         if (now >= id->death) {
 442                                 debug("expiring key '%s'", id->comment);
 443                                 TAILQ_REMOVE(&tab->idlist, id, next);
 444                                 free_identity(id);
 445                                 tab->nentries--;
 446                         } else
 447                                 deadline = (deadline == 0) ? id->death :
 448                                     MIN(deadline, id->death);
 449                 }
 450         }
 451         if (deadline == 0 || deadline <= now)
 452                 return 0;
 453         else
 454                 return (deadline - now);
 455 }
 456
 457 static void
 458 process_add_identity(SocketEntry *e, int version)
 459 {
 460         Idtab *tab = idtab_lookup(version);
 461         Identity *id;
 462         int type, success = 0, death = 0, confirm = 0;
 463         char *type_name, *comment;
 464         Key *k = NULL;
 465
 466         switch (version) {
 467         case 1:
 468                 k = key_new_private(KEY_RSA1);
 469                 (void) buffer_get_int(&e->request);             /* ignored */
 470                 buffer_get_bignum(&e->request, k->rsa->n);
 471                 buffer_get_bignum(&e->request, k->rsa->e);
 472                 buffer_get_bignum(&e->request, k->rsa->d);
 473                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 474
 475                 /* SSH and SSL have p and q swapped */
 476                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 477                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 478
 479                 /* Generate additional parameters */
 480                 rsa_generate_additional_parameters(k->rsa);
 481                 break;
 482         case 2:
 483                 type_name = buffer_get_string(&e->request, NULL);
 484                 type = key_type_from_name(type_name);
 485                 xfree(type_name);
 486                 switch (type) {
 487                 case KEY_DSA:
 488                         k = key_new_private(type);
 489                         buffer_get_bignum2(&e->request, k->dsa->p);
 490                         buffer_get_bignum2(&e->request, k->dsa->q);
 491                         buffer_get_bignum2(&e->request, k->dsa->g);
 492                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 493                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 494                         break;
 495                 case KEY_RSA:
 496                         k = key_new_private(type);
 497                         buffer_get_bignum2(&e->request, k->rsa->n);
 498                         buffer_get_bignum2(&e->request, k->rsa->e);
 499                         buffer_get_bignum2(&e->request, k->rsa->d);
 500                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 501                         buffer_get_bignum2(&e->request, k->rsa->p);
 502                         buffer_get_bignum2(&e->request, k->rsa->q);
 503
 504                         /* Generate additional parameters */
 505                         rsa_generate_additional_parameters(k->rsa);
 506                         break;
 507                 default:
 508                         buffer_clear(&e->request);
 509                         goto send;
 510                 }
 511                 break;
 512         }
 513         /* enable blinding */
 514         switch (k->type) {
 515         case KEY_RSA:
 516         case KEY_RSA1:
 517                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 518                         error("process_add_identity: RSA_blinding_on failed");
 519                         key_free(k);
 520                         goto send;
 521                 }
 522                 break;
 523         }
 524         comment = buffer_get_string(&e->request, NULL);
 525         if (k == NULL) {
 526                 xfree(comment);
 527                 goto send;
 528         }
 529         success = 1;
 530         while (buffer_len(&e->request)) {
 531                 switch (buffer_get_char(&e->request)) {
 532                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 533                         death = time(NULL) + buffer_get_int(&e->request);
 534                         break;
 535                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 536                         confirm = 1;
 537                         break;
 538                 default:
 539                         break;
 540                 }
 541         }
 542         if (lifetime && !death)
 543                 death = time(NULL) + lifetime;
 544         if ((id = lookup_identity(k, version)) == NULL) {
 545                 id = xmalloc(sizeof(Identity));
 546                 id->key = k;
 547                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 548                 /* Increment the number of identities. */
 549                 tab->nentries++;
 550         } else {
 551                 key_free(k);
 552                 xfree(id->comment);
 553         }
 554         id->comment = comment;
 555         id->death = death;
 556         id->confirm = confirm;
 557 send:
 558         buffer_put_int(&e->output, 1);
 559         buffer_put_char(&e->output,
 560             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 561 }
 562
 563 /* XXX todo: encrypt sensitive data with passphrase */
 564 static void
 565 process_lock_agent(SocketEntry *e, int lock)
 566 {
 567         int success = 0;
 568         char *passwd;
 569
 570         passwd = buffer_get_string(&e->request, NULL);
 571         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 572                 locked = 0;
 573                 memset(lock_passwd, 0, strlen(lock_passwd));
 574                 xfree(lock_passwd);
 575                 lock_passwd = NULL;
 576                 success = 1;
 577         } else if (!locked && lock) {
 578                 locked = 1;
 579                 lock_passwd = xstrdup(passwd);
 580                 success = 1;
 581         }
 582         memset(passwd, 0, strlen(passwd));
 583         xfree(passwd);
 584
 585         buffer_put_int(&e->output, 1);
 586         buffer_put_char(&e->output,
 587             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 588 }
 589
 590 static void
 591 no_identities(SocketEntry *e, u_int type)
 592 {
 593         Buffer msg;
 594
 595         buffer_init(&msg);
 596         buffer_put_char(&msg,
 597             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 598             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 599         buffer_put_int(&msg, 0);
 600         buffer_put_int(&e->output, buffer_len(&msg));
 601         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 602         buffer_free(&msg);
 603 }
 604
 605 #ifdef SMARTCARD
 606 static void
 607 process_add_smartcard_key (SocketEntry *e)
 608 {
 609         char *sc_reader_id = NULL, *pin;
 610         int i, version, success = 0, death = 0, confirm = 0;
 611         Key **keys, *k;
 612         Identity *id;
 613         Idtab *tab;
 614
 615         sc_reader_id = buffer_get_string(&e->request, NULL);
 616         pin = buffer_get_string(&e->request, NULL);
 617
 618         while (buffer_len(&e->request)) {
 619                 switch (buffer_get_char(&e->request)) {
 620                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 621                         death = time(NULL) + buffer_get_int(&e->request);
 622                         break;
 623                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 624                         confirm = 1;
 625                         break;
 626                 default:
 627                         break;
 628                 }
 629         }
 630         if (lifetime && !death)
 631                 death = time(NULL) + lifetime;
 632
 633         keys = sc_get_keys(sc_reader_id, pin);
 634         xfree(sc_reader_id);
 635         xfree(pin);
 636
 637         if (keys == NULL || keys[0] == NULL) {
 638                 error("sc_get_keys failed");
 639                 goto send;
 640         }
 641         for (i = 0; keys[i] != NULL; i++) {
 642                 k = keys[i];
 643                 version = k->type == KEY_RSA1 ? 1 : 2;
 644                 tab = idtab_lookup(version);
 645                 if (lookup_identity(k, version) == NULL) {
 646                         id = xmalloc(sizeof(Identity));
 647                         id->key = k;
 648                         id->comment = sc_get_key_label(k);
 649                         id->death = death;
 650                         id->confirm = confirm;
 651                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 652                         tab->nentries++;
 653                         success = 1;
 654                 } else {
 655                         key_free(k);
 656                 }
 657                 keys[i] = NULL;
 658         }
 659         xfree(keys);
 660 send:
 661         buffer_put_int(&e->output, 1);
 662         buffer_put_char(&e->output,
 663             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 664 }
 665
 666 static void
 667 process_remove_smartcard_key(SocketEntry *e)
 668 {
 669         char *sc_reader_id = NULL, *pin;
 670         int i, version, success = 0;
 671         Key **keys, *k = NULL;
 672         Identity *id;
 673         Idtab *tab;
 674
 675         sc_reader_id = buffer_get_string(&e->request, NULL);
 676         pin = buffer_get_string(&e->request, NULL);
 677         keys = sc_get_keys(sc_reader_id, pin);
 678         xfree(sc_reader_id);
 679         xfree(pin);
 680
 681         if (keys == NULL || keys[0] == NULL) {
 682                 error("sc_get_keys failed");
 683                 goto send;
 684         }
 685         for (i = 0; keys[i] != NULL; i++) {
 686                 k = keys[i];
 687                 version = k->type == KEY_RSA1 ? 1 : 2;
 688                 if ((id = lookup_identity(k, version)) != NULL) {
 689                         tab = idtab_lookup(version);
 690                         TAILQ_REMOVE(&tab->idlist, id, next);
 691                         tab->nentries--;
 692                         free_identity(id);
 693                         success = 1;
 694                 }
 695                 key_free(k);
 696                 keys[i] = NULL;
 697         }
 698         xfree(keys);
 699 send:
 700         buffer_put_int(&e->output, 1);
 701         buffer_put_char(&e->output,
 702             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 703 }
 704 #endif /* SMARTCARD */
 705
 706 /* dispatch incoming messages */
 707
 708 static void
 709 process_message(SocketEntry *e)
 710 {
 711         u_int msg_len, type;
 712         u_char *cp;
 713
 714         if (buffer_len(&e->input) < 5)
 715                 return;         /* Incomplete message. */
 716         cp = buffer_ptr(&e->input);
 717         msg_len = get_u32(cp);
 718         if (msg_len > 256 * 1024) {
 719                 close_socket(e);
 720                 return;
 721         }
 722         if (buffer_len(&e->input) < msg_len + 4)
 723                 return;
 724
 725         /* move the current input to e->request */
 726         buffer_consume(&e->input, 4);
 727         buffer_clear(&e->request);
 728         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 729         buffer_consume(&e->input, msg_len);
 730         type = buffer_get_char(&e->request);
 731
 732         /* check wheter agent is locked */
 733         if (locked && type != SSH_AGENTC_UNLOCK) {
 734                 buffer_clear(&e->request);
 735                 switch (type) {
 736                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 737                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 738                         /* send empty lists */
 739                         no_identities(e, type);
 740                         break;
 741                 default:
 742                         /* send a fail message for all other request types */
 743                         buffer_put_int(&e->output, 1);
 744                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 745                 }
 746                 return;
 747         }
 748
 749         debug("type %d", type);
 750         switch (type) {
 751         case SSH_AGENTC_LOCK:
 752         case SSH_AGENTC_UNLOCK:
 753                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 754                 break;
 755         /* ssh1 */
 756         case SSH_AGENTC_RSA_CHALLENGE:
 757                 process_authentication_challenge1(e);
 758                 break;
 759         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 760                 process_request_identities(e, 1);
 761                 break;
 762         case SSH_AGENTC_ADD_RSA_IDENTITY:
 763         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 764                 process_add_identity(e, 1);
 765                 break;
 766         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 767                 process_remove_identity(e, 1);
 768                 break;
 769         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 770                 process_remove_all_identities(e, 1);
 771                 break;
 772         /* ssh2 */
 773         case SSH2_AGENTC_SIGN_REQUEST:
 774                 process_sign_request2(e);
 775                 break;
 776         case SSH2_AGENTC_REQUEST_IDENTITIES:
 777                 process_request_identities(e, 2);
 778                 break;
 779         case SSH2_AGENTC_ADD_IDENTITY:
 780         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 781                 process_add_identity(e, 2);
 782                 break;
 783         case SSH2_AGENTC_REMOVE_IDENTITY:
 784                 process_remove_identity(e, 2);
 785                 break;
 786         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 787                 process_remove_all_identities(e, 2);
 788                 break;
 789 #ifdef SMARTCARD
 790         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 791         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 792                 process_add_smartcard_key(e);
 793                 break;
 794         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 795                 process_remove_smartcard_key(e);
 796                 break;
 797 #endif /* SMARTCARD */
 798         default:
 799                 /* Unknown message.  Respond with failure. */
 800                 error("Unknown message %d", type);
 801                 buffer_clear(&e->request);
 802                 buffer_put_int(&e->output, 1);
 803                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 804                 break;
 805         }
 806 }
 807
 808 static void
 809 new_socket(sock_type type, int fd)
 810 {
 811         u_int i, old_alloc, new_alloc;
 812
 813         set_nonblock(fd);
 814
 815         if (fd > max_fd)
 816                 max_fd = fd;
 817
 818         for (i = 0; i < sockets_alloc; i++)
 819                 if (sockets[i].type == AUTH_UNUSED) {
 820                         sockets[i].fd = fd;
 821                         buffer_init(&sockets[i].input);
 822                         buffer_init(&sockets[i].output);
 823                         buffer_init(&sockets[i].request);
 824                         sockets[i].type = type;
 825                         return;
 826                 }
 827         old_alloc = sockets_alloc;
 828         new_alloc = sockets_alloc + 10;
 829         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 830         for (i = old_alloc; i < new_alloc; i++)
 831                 sockets[i].type = AUTH_UNUSED;
 832         sockets_alloc = new_alloc;
 833         sockets[old_alloc].fd = fd;
 834         buffer_init(&sockets[old_alloc].input);
 835         buffer_init(&sockets[old_alloc].output);
 836         buffer_init(&sockets[old_alloc].request);
 837         sockets[old_alloc].type = type;
 838 }
 839
 840 static int
 841 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
 842     struct timeval **tvpp)
 843 {
 844         u_int i, sz, deadline;
 845         int n = 0;
 846         static struct timeval tv;
 847
 848         for (i = 0; i < sockets_alloc; i++) {
 849                 switch (sockets[i].type) {
 850                 case AUTH_SOCKET:
 851                 case AUTH_CONNECTION:
 852                         n = MAX(n, sockets[i].fd);
 853                         break;
 854                 case AUTH_UNUSED:
 855                         break;
 856                 default:
 857                         fatal("Unknown socket type %d", sockets[i].type);
 858                         break;
 859                 }
 860         }
 861
 862         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 863         if (*fdrp == NULL || sz > *nallocp) {
 864                 if (*fdrp)
 865                         xfree(*fdrp);
 866                 if (*fdwp)
 867                         xfree(*fdwp);
 868                 *fdrp = xmalloc(sz);
 869                 *fdwp = xmalloc(sz);
 870                 *nallocp = sz;
 871         }
 872         if (n < *fdl)
 873                 debug("XXX shrink: %d < %d", n, *fdl);
 874         *fdl = n;
 875         memset(*fdrp, 0, sz);
 876         memset(*fdwp, 0, sz);
 877
 878         for (i = 0; i < sockets_alloc; i++) {
 879                 switch (sockets[i].type) {
 880                 case AUTH_SOCKET:
 881                 case AUTH_CONNECTION:
 882                         FD_SET(sockets[i].fd, *fdrp);
 883                         if (buffer_len(&sockets[i].output) > 0)
 884                                 FD_SET(sockets[i].fd, *fdwp);
 885                         break;
 886                 default:
 887                         break;
 888                 }
 889         }
 890         deadline = reaper();
 891         if (parent_alive_interval != 0)
 892                 deadline = (deadline == 0) ? parent_alive_interval :
 893                     MIN(deadline, parent_alive_interval);
 894         if (deadline == 0) {
 895                 *tvpp = NULL;
 896         } else {
 897                 tv.tv_sec = deadline;
 898                 tv.tv_usec = 0;
 899                 *tvpp = &tv;
 900         }
 901         return (1);
 902 }
 903
 904 static void
 905 after_select(fd_set *readset, fd_set *writeset)
 906 {
 907         struct sockaddr_un sunaddr;
 908         socklen_t slen;
 909         char buf[1024];
 910         int len, sock;
 911         u_int i;
 912         uid_t euid;
 913         gid_t egid;
 914
 915         for (i = 0; i < sockets_alloc; i++)
 916                 switch (sockets[i].type) {
 917                 case AUTH_UNUSED:
 918                         break;
 919                 case AUTH_SOCKET:
 920                         if (FD_ISSET(sockets[i].fd, readset)) {
 921                                 slen = sizeof(sunaddr);
 922                                 sock = accept(sockets[i].fd,
 923                                     (struct sockaddr *)&sunaddr, &slen);
 924                                 if (sock < 0) {
 925                                         error("accept from AUTH_SOCKET: %s",
 926                                             strerror(errno));
 927                                         break;
 928                                 }
 929                                 if (getpeereid(sock, &euid, &egid) < 0) {
 930                                         error("getpeereid %d failed: %s",
 931                                             sock, strerror(errno));
 932                                         close(sock);
 933                                         break;
 934                                 }
 935                                 if ((euid != 0) && (getuid() != euid)) {
 936                                         error("uid mismatch: "
 937                                             "peer euid %u != uid %u",
 938                                             (u_int) euid, (u_int) getuid());
 939                                         close(sock);
 940                                         break;
 941                                 }
 942                                 new_socket(AUTH_CONNECTION, sock);
 943                         }
 944                         break;
 945                 case AUTH_CONNECTION:
 946                         if (buffer_len(&sockets[i].output) > 0 &&
 947                             FD_ISSET(sockets[i].fd, writeset)) {
 948                                 do {
 949                                         len = write(sockets[i].fd,
 950                                             buffer_ptr(&sockets[i].output),
 951                                             buffer_len(&sockets[i].output));
 952                                         if (len == -1 && (errno == EAGAIN ||
 953                                             errno == EINTR))
 954                                                 continue;
 955                                         break;
 956                                 } while (1);
 957                                 if (len <= 0) {
 958                                         close_socket(&sockets[i]);
 959                                         break;
 960                                 }
 961                                 buffer_consume(&sockets[i].output, len);
 962                         }
 963                         if (FD_ISSET(sockets[i].fd, readset)) {
 964                                 do {
 965                                         len = read(sockets[i].fd, buf, sizeof(buf));
 966                                         if (len == -1 && (errno == EAGAIN ||
 967                                             errno == EINTR))
 968                                                 continue;
 969                                         break;
 970                                 } while (1);
 971                                 if (len <= 0) {
 972                                         close_socket(&sockets[i]);
 973                                         break;
 974                                 }
 975                                 buffer_append(&sockets[i].input, buf, len);
 976                                 process_message(&sockets[i]);
 977                         }
 978                         break;
 979                 default:
 980                         fatal("Unknown type %d", sockets[i].type);
 981                 }
 982 }
 983
 984 static void
 985 cleanup_socket(void)
 986 {
 987         if (socket_name[0])
 988                 unlink(socket_name);
 989         if (socket_dir[0])
 990                 rmdir(socket_dir);
 991 }
 992
 993 void
 994 cleanup_exit(int i)
 995 {
 996         cleanup_socket();
 997         _exit(i);
 998 }
 999
1000 /*ARGSUSED*/
1001 static void
1002 cleanup_handler(int sig)
1003 {
1004         cleanup_socket();
1005         _exit(2);
1006 }
1007
1008 static void
1009 check_parent_exists(void)
1010 {
1011         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
1012                 /* printf("Parent has died - Authentication agent exiting.\n"); */
1013                 cleanup_socket();
1014                 _exit(2);
1015         }
1016 }
1017
1018 static void
1019 usage(void)
1020 {
1021         fprintf(stderr, "usage: %s [options] [command [arg ...]]\n",
1022             __progname);
1023         fprintf(stderr, "Options:\n");
1024         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1025         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1026         fprintf(stderr, "  -k          Kill the current agent.\n");
1027         fprintf(stderr, "  -d          Debug mode.\n");
1028         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1029         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1030         exit(1);
1031 }
1032
1033 int
1034 main(int ac, char **av)
1035 {
1036         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1037         int sock, fd, ch, result, saved_errno;
1038         u_int nalloc;
1039         char *shell, *format, *pidstr, *agentsocket = NULL;
1040         fd_set *readsetp = NULL, *writesetp = NULL;
1041         struct sockaddr_un sunaddr;
1042 #ifdef HAVE_SETRLIMIT
1043         struct rlimit rlim;
1044 #endif
1045         int prev_mask;
1046         extern int optind;
1047         extern char *optarg;
1048         pid_t pid;
1049         char pidstrbuf[1 + 3 * sizeof pid];
1050         struct timeval *tvp = NULL;
1051
1052         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1053         sanitise_stdfd();
1054
1055         /* drop */
1056         setegid(getgid());
1057         setgid(getgid());
1058         setuid(geteuid());
1059
1060 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1061         /* Disable ptrace on Linux without sgid bit */
1062         prctl(PR_SET_DUMPABLE, 0);
1063 #endif
1064
1065         SSLeay_add_all_algorithms();
1066
1067         __progname = ssh_get_progname(av[0]);
1068         init_rng();
1069         seed_rng();
1070
1071         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1072                 switch (ch) {
1073                 case 'c':
1074                         if (s_flag)
1075                                 usage();
1076                         c_flag++;
1077                         break;
1078                 case 'k':
1079                         k_flag++;
1080                         break;
1081                 case 's':
1082                         if (c_flag)
1083                                 usage();
1084                         s_flag++;
1085                         break;
1086                 case 'd':
1087                         if (d_flag)
1088                                 usage();
1089                         d_flag++;
1090                         break;
1091                 case 'a':
1092                         agentsocket = optarg;
1093                         break;
1094                 case 't':
1095                         if ((lifetime = convtime(optarg)) == -1) {
1096                                 fprintf(stderr, "Invalid lifetime\n");
1097                                 usage();
1098                         }
1099                         break;
1100                 default:
1101                         usage();
1102                 }
1103         }
1104         ac -= optind;
1105         av += optind;
1106
1107         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1108                 usage();
1109
1110         if (ac == 0 && !c_flag && !s_flag) {
1111                 shell = getenv("SHELL");
1112                 if (shell != NULL &&
1113                     strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1114                         c_flag = 1;
1115         }
1116         if (k_flag) {
1117                 const char *errstr = NULL;
1118
1119                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1120                 if (pidstr == NULL) {
1121                         fprintf(stderr, "%s not set, cannot kill agent\n",
1122                             SSH_AGENTPID_ENV_NAME);
1123                         exit(1);
1124                 }
1125                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1126                 if (errstr) {
1127                         fprintf(stderr,
1128                             "%s=\"%s\", which is not a good PID: %s\n",
1129                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1130                         exit(1);
1131                 }
1132                 if (kill(pid, SIGTERM) == -1) {
1133                         perror("kill");
1134                         exit(1);
1135                 }
1136                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1137                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1138                 printf(format, SSH_AGENTPID_ENV_NAME);
1139                 printf("echo Agent pid %ld killed;\n", (long)pid);
1140                 exit(0);
1141         }
1142         parent_pid = getpid();
1143
1144         if (agentsocket == NULL) {
1145                 /* Create private directory for agent socket */
1146                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1147                 if (mkdtemp(socket_dir) == NULL) {
1148                         perror("mkdtemp: private socket dir");
1149                         exit(1);
1150                 }
1151                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1152                     (long)parent_pid);
1153         } else {
1154                 /* Try to use specified agent socket */
1155                 socket_dir[0] = '\0';
1156                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1157         }
1158
1159         /*
1160          * Create socket early so it will exist before command gets run from
1161          * the parent.
1162          */
1163         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1164         if (sock < 0) {
1165                 perror("socket");
1166                 *socket_name = '\0'; /* Don't unlink any existing file */
1167                 cleanup_exit(1);
1168         }
1169         memset(&sunaddr, 0, sizeof(sunaddr));
1170         sunaddr.sun_family = AF_UNIX;
1171         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1172         prev_mask = umask(0177);
1173         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1174                 perror("bind");
1175                 *socket_name = '\0'; /* Don't unlink any existing file */
1176                 umask(prev_mask);
1177                 cleanup_exit(1);
1178         }
1179         umask(prev_mask);
1180         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1181                 perror("listen");
1182                 cleanup_exit(1);
1183         }
1184
1185         /*
1186          * Fork, and have the parent execute the command, if any, or present
1187          * the socket data.  The child continues as the authentication agent.
1188          */
1189         if (d_flag) {
1190                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1191                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1192                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1193                     SSH_AUTHSOCKET_ENV_NAME);
1194                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1195                 goto skip;
1196         }
1197         pid = fork();
1198         if (pid == -1) {
1199                 perror("fork");
1200                 cleanup_exit(1);
1201         }
1202         if (pid != 0) {         /* Parent - execute the given command. */
1203                 close(sock);
1204                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1205                 if (ac == 0) {
1206                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1207                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1208                             SSH_AUTHSOCKET_ENV_NAME);
1209                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1210                             SSH_AGENTPID_ENV_NAME);
1211                         printf("echo Agent pid %ld;\n", (long)pid);
1212                         exit(0);
1213                 }
1214                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1215                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1216                         perror("setenv");
1217                         exit(1);
1218                 }
1219                 execvp(av[0], av);
1220                 perror(av[0]);
1221                 exit(1);
1222         }
1223         /* child */
1224         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1225
1226         if (setsid() == -1) {
1227                 error("setsid: %s", strerror(errno));
1228                 cleanup_exit(1);
1229         }
1230
1231         (void)chdir("/");
1232         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1233                 /* XXX might close listen socket */
1234                 (void)dup2(fd, STDIN_FILENO);
1235                 (void)dup2(fd, STDOUT_FILENO);
1236                 (void)dup2(fd, STDERR_FILENO);
1237                 if (fd > 2)
1238                         close(fd);
1239         }
1240
1241 #ifdef HAVE_SETRLIMIT
1242         /* deny core dumps, since memory contains unencrypted private keys */
1243         rlim.rlim_cur = rlim.rlim_max = 0;
1244         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1245                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1246                 cleanup_exit(1);
1247         }
1248 #endif
1249
1250 skip:
1251         new_socket(AUTH_SOCKET, sock);
1252         if (ac > 0)
1253                 parent_alive_interval = 10;
1254         idtab_init();
1255         if (!d_flag)
1256                 signal(SIGINT, SIG_IGN);
1257         signal(SIGPIPE, SIG_IGN);
1258         signal(SIGHUP, cleanup_handler);
1259         signal(SIGTERM, cleanup_handler);
1260         nalloc = 0;
1261
1262         while (1) {
1263                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1264                 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1265                 saved_errno = errno;
1266                 if (parent_alive_interval != 0)
1267                         check_parent_exists();
1268                 (void) reaper();        /* remove expired keys */
1269                 if (result < 0) {
1270                         if (saved_errno == EINTR)
1271                                 continue;
1272                         fatal("select: %s", strerror(saved_errno));
1273                 } else if (result > 0)
1274                         after_select(readsetp, writesetp);
1275         }
1276         /* NOTREACHED */
1277 }