crypto/openssh-4/ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.154 2007/02/28 00:55:30 dtucker 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
  55 #include <errno.h>
  56 #include <fcntl.h>
  57 #ifdef HAVE_PATHS_H
  58 # include <paths.h>
  59 #endif
  60 #include <signal.h>
  61 #include <stdarg.h>
  62 #include <stdio.h>
  63 #include <stdlib.h>
  64 #include <time.h>
  65 #include <string.h>
  66 #include <unistd.h>
  67
  68 #include "xmalloc.h"
  69 #include "ssh.h"
  70 #include "rsa.h"
  71 #include "buffer.h"
  72 #include "key.h"
  73 #include "authfd.h"
  74 #include "compat.h"
  75 #include "log.h"
  76 #include "misc.h"
  77
  78 #ifdef SMARTCARD
  79 #include "scard.h"
  80 #endif
  81
  82 #if defined(HAVE_SYS_PRCTL_H)
  83 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  84 #endif
  85
  86 typedef enum {
  87         AUTH_UNUSED,
  88         AUTH_SOCKET,
  89         AUTH_CONNECTION
  90 } sock_type;
  91
  92 typedef struct {
  93         int fd;
  94         sock_type type;
  95         Buffer input;
  96         Buffer output;
  97         Buffer request;
  98 } SocketEntry;
  99
 100 u_int sockets_alloc = 0;
 101 SocketEntry *sockets = NULL;
 102
 103 typedef struct identity {
 104         TAILQ_ENTRY(identity) next;
 105         Key *key;
 106         char *comment;
 107         u_int death;
 108         u_int confirm;
 109 } Identity;
 110
 111 typedef struct {
 112         int nentries;
 113         TAILQ_HEAD(idqueue, identity) idlist;
 114 } Idtab;
 115
 116 /* private key table, one per protocol version */
 117 Idtab idtable[3];
 118
 119 int max_fd = 0;
 120
 121 /* pid of shell == parent of agent */
 122 pid_t parent_pid = -1;
 123
 124 /* pathname and directory for AUTH_SOCKET */
 125 char socket_name[MAXPATHLEN];
 126 char socket_dir[MAXPATHLEN];
 127
 128 /* locking */
 129 int locked = 0;
 130 char *lock_passwd = NULL;
 131
 132 extern char *__progname;
 133
 134 /* Default lifetime (0 == forever) */
 135 static int lifetime = 0;
 136
 137 static void
 138 close_socket(SocketEntry *e)
 139 {
 140         close(e->fd);
 141         e->fd = -1;
 142         e->type = AUTH_UNUSED;
 143         buffer_free(&e->input);
 144         buffer_free(&e->output);
 145         buffer_free(&e->request);
 146 }
 147
 148 static void
 149 idtab_init(void)
 150 {
 151         int i;
 152
 153         for (i = 0; i <=2; i++) {
 154                 TAILQ_INIT(&idtable[i].idlist);
 155                 idtable[i].nentries = 0;
 156         }
 157 }
 158
 159 /* return private key table for requested protocol version */
 160 static Idtab *
 161 idtab_lookup(int version)
 162 {
 163         if (version < 1 || version > 2)
 164                 fatal("internal error, bad protocol version %d", version);
 165         return &idtable[version];
 166 }
 167
 168 static void
 169 free_identity(Identity *id)
 170 {
 171         key_free(id->key);
 172         xfree(id->comment);
 173         xfree(id);
 174 }
 175
 176 /* return matching private key for given public key */
 177 static Identity *
 178 lookup_identity(Key *key, int version)
 179 {
 180         Identity *id;
 181
 182         Idtab *tab = idtab_lookup(version);
 183         TAILQ_FOREACH(id, &tab->idlist, next) {
 184                 if (key_equal(key, id->key))
 185                         return (id);
 186         }
 187         return (NULL);
 188 }
 189
 190 /* Check confirmation of keysign request */
 191 static int
 192 confirm_key(Identity *id)
 193 {
 194         char *p;
 195         int ret = -1;
 196
 197         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 198         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 199             id->comment, p))
 200                 ret = 0;
 201         xfree(p);
 202
 203         return (ret);
 204 }
 205
 206 /* send list of supported public keys to 'client' */
 207 static void
 208 process_request_identities(SocketEntry *e, int version)
 209 {
 210         Idtab *tab = idtab_lookup(version);
 211         Identity *id;
 212         Buffer msg;
 213
 214         buffer_init(&msg);
 215         buffer_put_char(&msg, (version == 1) ?
 216             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 217         buffer_put_int(&msg, tab->nentries);
 218         TAILQ_FOREACH(id, &tab->idlist, next) {
 219                 if (id->key->type == KEY_RSA1) {
 220                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 221                         buffer_put_bignum(&msg, id->key->rsa->e);
 222                         buffer_put_bignum(&msg, id->key->rsa->n);
 223                 } else {
 224                         u_char *blob;
 225                         u_int blen;
 226                         key_to_blob(id->key, &blob, &blen);
 227                         buffer_put_string(&msg, blob, blen);
 228                         xfree(blob);
 229                 }
 230                 buffer_put_cstring(&msg, id->comment);
 231         }
 232         buffer_put_int(&e->output, buffer_len(&msg));
 233         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 234         buffer_free(&msg);
 235 }
 236
 237 /* ssh1 only */
 238 static void
 239 process_authentication_challenge1(SocketEntry *e)
 240 {
 241         u_char buf[32], mdbuf[16], session_id[16];
 242         u_int response_type;
 243         BIGNUM *challenge;
 244         Identity *id;
 245         int i, len;
 246         Buffer msg;
 247         MD5_CTX md;
 248         Key *key;
 249
 250         buffer_init(&msg);
 251         key = key_new(KEY_RSA1);
 252         if ((challenge = BN_new()) == NULL)
 253                 fatal("process_authentication_challenge1: BN_new failed");
 254
 255         (void) buffer_get_int(&e->request);                     /* ignored */
 256         buffer_get_bignum(&e->request, key->rsa->e);
 257         buffer_get_bignum(&e->request, key->rsa->n);
 258         buffer_get_bignum(&e->request, challenge);
 259
 260         /* Only protocol 1.1 is supported */
 261         if (buffer_len(&e->request) == 0)
 262                 goto failure;
 263         buffer_get(&e->request, session_id, 16);
 264         response_type = buffer_get_int(&e->request);
 265         if (response_type != 1)
 266                 goto failure;
 267
 268         id = lookup_identity(key, 1);
 269         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 270                 Key *private = id->key;
 271                 /* Decrypt the challenge using the private key. */
 272                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 273                         goto failure;
 274
 275                 /* The response is MD5 of decrypted challenge plus session id. */
 276                 len = BN_num_bytes(challenge);
 277                 if (len <= 0 || len > 32) {
 278                         logit("process_authentication_challenge: bad challenge length %d", len);
 279                         goto failure;
 280                 }
 281                 memset(buf, 0, 32);
 282                 BN_bn2bin(challenge, buf + 32 - len);
 283                 MD5_Init(&md);
 284                 MD5_Update(&md, buf, 32);
 285                 MD5_Update(&md, session_id, 16);
 286                 MD5_Final(mdbuf, &md);
 287
 288                 /* Send the response. */
 289                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 290                 for (i = 0; i < 16; i++)
 291                         buffer_put_char(&msg, mdbuf[i]);
 292                 goto send;
 293         }
 294
 295 failure:
 296         /* Unknown identity or protocol error.  Send failure. */
 297         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 298 send:
 299         buffer_put_int(&e->output, buffer_len(&msg));
 300         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 301         key_free(key);
 302         BN_clear_free(challenge);
 303         buffer_free(&msg);
 304 }
 305
 306 /* ssh2 only */
 307 static void
 308 process_sign_request2(SocketEntry *e)
 309 {
 310         u_char *blob, *data, *signature = NULL;
 311         u_int blen, dlen, slen = 0;
 312         extern int datafellows;
 313         int ok = -1, flags;
 314         Buffer msg;
 315         Key *key;
 316
 317         datafellows = 0;
 318
 319         blob = buffer_get_string(&e->request, &blen);
 320         data = buffer_get_string(&e->request, &dlen);
 321
 322         flags = buffer_get_int(&e->request);
 323         if (flags & SSH_AGENT_OLD_SIGNATURE)
 324                 datafellows = SSH_BUG_SIGBLOB;
 325
 326         key = key_from_blob(blob, blen);
 327         if (key != NULL) {
 328                 Identity *id = lookup_identity(key, 2);
 329                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 330                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 331                 key_free(key);
 332         }
 333         buffer_init(&msg);
 334         if (ok == 0) {
 335                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 336                 buffer_put_string(&msg, signature, slen);
 337         } else {
 338                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 339         }
 340         buffer_put_int(&e->output, buffer_len(&msg));
 341         buffer_append(&e->output, buffer_ptr(&msg),
 342             buffer_len(&msg));
 343         buffer_free(&msg);
 344         xfree(data);
 345         xfree(blob);
 346         if (signature != NULL)
 347                 xfree(signature);
 348 }
 349
 350 /* shared */
 351 static void
 352 process_remove_identity(SocketEntry *e, int version)
 353 {
 354         u_int blen, bits;
 355         int success = 0;
 356         Key *key = NULL;
 357         u_char *blob;
 358
 359         switch (version) {
 360         case 1:
 361                 key = key_new(KEY_RSA1);
 362                 bits = buffer_get_int(&e->request);
 363                 buffer_get_bignum(&e->request, key->rsa->e);
 364                 buffer_get_bignum(&e->request, key->rsa->n);
 365
 366                 if (bits != key_size(key))
 367                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 368                             key_size(key), bits);
 369                 break;
 370         case 2:
 371                 blob = buffer_get_string(&e->request, &blen);
 372                 key = key_from_blob(blob, blen);
 373                 xfree(blob);
 374                 break;
 375         }
 376         if (key != NULL) {
 377                 Identity *id = lookup_identity(key, version);
 378                 if (id != NULL) {
 379                         /*
 380                          * We have this key.  Free the old key.  Since we
 381                          * don't want to leave empty slots in the middle of
 382                          * the array, we actually free the key there and move
 383                          * all the entries between the empty slot and the end
 384                          * of the array.
 385                          */
 386                         Idtab *tab = idtab_lookup(version);
 387                         if (tab->nentries < 1)
 388                                 fatal("process_remove_identity: "
 389                                     "internal error: tab->nentries %d",
 390                                     tab->nentries);
 391                         TAILQ_REMOVE(&tab->idlist, id, next);
 392                         free_identity(id);
 393                         tab->nentries--;
 394                         success = 1;
 395                 }
 396                 key_free(key);
 397         }
 398         buffer_put_int(&e->output, 1);
 399         buffer_put_char(&e->output,
 400             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 401 }
 402
 403 static void
 404 process_remove_all_identities(SocketEntry *e, int version)
 405 {
 406         Idtab *tab = idtab_lookup(version);
 407         Identity *id;
 408
 409         /* Loop over all identities and clear the keys. */
 410         for (id = TAILQ_FIRST(&tab->idlist); id;
 411             id = TAILQ_FIRST(&tab->idlist)) {
 412                 TAILQ_REMOVE(&tab->idlist, id, next);
 413                 free_identity(id);
 414         }
 415
 416         /* Mark that there are no identities. */
 417         tab->nentries = 0;
 418
 419         /* Send success. */
 420         buffer_put_int(&e->output, 1);
 421         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 422 }
 423
 424 static void
 425 reaper(void)
 426 {
 427         u_int now = time(NULL);
 428         Identity *id, *nxt;
 429         int version;
 430         Idtab *tab;
 431
 432         for (version = 1; version < 3; version++) {
 433                 tab = idtab_lookup(version);
 434                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 435                         nxt = TAILQ_NEXT(id, next);
 436                         if (id->death != 0 && now >= id->death) {
 437                                 debug("expiring key '%s'", id->comment);
 438                                 TAILQ_REMOVE(&tab->idlist, id, next);
 439                                 free_identity(id);
 440                                 tab->nentries--;
 441                         }
 442                 }
 443         }
 444 }
 445
 446 static void
 447 process_add_identity(SocketEntry *e, int version)
 448 {
 449         Idtab *tab = idtab_lookup(version);
 450         int type, success = 0, death = 0, confirm = 0;
 451         char *type_name, *comment;
 452         Key *k = NULL;
 453
 454         switch (version) {
 455         case 1:
 456                 k = key_new_private(KEY_RSA1);
 457                 (void) buffer_get_int(&e->request);             /* ignored */
 458                 buffer_get_bignum(&e->request, k->rsa->n);
 459                 buffer_get_bignum(&e->request, k->rsa->e);
 460                 buffer_get_bignum(&e->request, k->rsa->d);
 461                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 462
 463                 /* SSH and SSL have p and q swapped */
 464                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 465                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 466
 467                 /* Generate additional parameters */
 468                 rsa_generate_additional_parameters(k->rsa);
 469                 break;
 470         case 2:
 471                 type_name = buffer_get_string(&e->request, NULL);
 472                 type = key_type_from_name(type_name);
 473                 xfree(type_name);
 474                 switch (type) {
 475                 case KEY_DSA:
 476                         k = key_new_private(type);
 477                         buffer_get_bignum2(&e->request, k->dsa->p);
 478                         buffer_get_bignum2(&e->request, k->dsa->q);
 479                         buffer_get_bignum2(&e->request, k->dsa->g);
 480                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 481                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 482                         break;
 483                 case KEY_RSA:
 484                         k = key_new_private(type);
 485                         buffer_get_bignum2(&e->request, k->rsa->n);
 486                         buffer_get_bignum2(&e->request, k->rsa->e);
 487                         buffer_get_bignum2(&e->request, k->rsa->d);
 488                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 489                         buffer_get_bignum2(&e->request, k->rsa->p);
 490                         buffer_get_bignum2(&e->request, k->rsa->q);
 491
 492                         /* Generate additional parameters */
 493                         rsa_generate_additional_parameters(k->rsa);
 494                         break;
 495                 default:
 496                         buffer_clear(&e->request);
 497                         goto send;
 498                 }
 499                 break;
 500         }
 501         /* enable blinding */
 502         switch (k->type) {
 503         case KEY_RSA:
 504         case KEY_RSA1:
 505                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 506                         error("process_add_identity: RSA_blinding_on failed");
 507                         key_free(k);
 508                         goto send;
 509                 }
 510                 break;
 511         }
 512         comment = buffer_get_string(&e->request, NULL);
 513         if (k == NULL) {
 514                 xfree(comment);
 515                 goto send;
 516         }
 517         success = 1;
 518         while (buffer_len(&e->request)) {
 519                 switch (buffer_get_char(&e->request)) {
 520                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 521                         death = time(NULL) + buffer_get_int(&e->request);
 522                         break;
 523                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 524                         confirm = 1;
 525                         break;
 526                 default:
 527                         break;
 528                 }
 529         }
 530         if (lifetime && !death)
 531                 death = time(NULL) + lifetime;
 532         if (lookup_identity(k, version) == NULL) {
 533                 Identity *id = xmalloc(sizeof(Identity));
 534                 id->key = k;
 535                 id->comment = comment;
 536                 id->death = death;
 537                 id->confirm = confirm;
 538                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 539                 /* Increment the number of identities. */
 540                 tab->nentries++;
 541         } else {
 542                 key_free(k);
 543                 xfree(comment);
 544         }
 545 send:
 546         buffer_put_int(&e->output, 1);
 547         buffer_put_char(&e->output,
 548             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 549 }
 550
 551 /* XXX todo: encrypt sensitive data with passphrase */
 552 static void
 553 process_lock_agent(SocketEntry *e, int lock)
 554 {
 555         int success = 0;
 556         char *passwd;
 557
 558         passwd = buffer_get_string(&e->request, NULL);
 559         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 560                 locked = 0;
 561                 memset(lock_passwd, 0, strlen(lock_passwd));
 562                 xfree(lock_passwd);
 563                 lock_passwd = NULL;
 564                 success = 1;
 565         } else if (!locked && lock) {
 566                 locked = 1;
 567                 lock_passwd = xstrdup(passwd);
 568                 success = 1;
 569         }
 570         memset(passwd, 0, strlen(passwd));
 571         xfree(passwd);
 572
 573         buffer_put_int(&e->output, 1);
 574         buffer_put_char(&e->output,
 575             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 576 }
 577
 578 static void
 579 no_identities(SocketEntry *e, u_int type)
 580 {
 581         Buffer msg;
 582
 583         buffer_init(&msg);
 584         buffer_put_char(&msg,
 585             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 586             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 587         buffer_put_int(&msg, 0);
 588         buffer_put_int(&e->output, buffer_len(&msg));
 589         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 590         buffer_free(&msg);
 591 }
 592
 593 #ifdef SMARTCARD
 594 static void
 595 process_add_smartcard_key (SocketEntry *e)
 596 {
 597         char *sc_reader_id = NULL, *pin;
 598         int i, version, success = 0, death = 0, confirm = 0;
 599         Key **keys, *k;
 600         Identity *id;
 601         Idtab *tab;
 602
 603         sc_reader_id = buffer_get_string(&e->request, NULL);
 604         pin = buffer_get_string(&e->request, NULL);
 605
 606         while (buffer_len(&e->request)) {
 607                 switch (buffer_get_char(&e->request)) {
 608                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 609                         death = time(NULL) + buffer_get_int(&e->request);
 610                         break;
 611                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 612                         confirm = 1;
 613                         break;
 614                 default:
 615                         break;
 616                 }
 617         }
 618         if (lifetime && !death)
 619                 death = time(NULL) + lifetime;
 620
 621         keys = sc_get_keys(sc_reader_id, pin);
 622         xfree(sc_reader_id);
 623         xfree(pin);
 624
 625         if (keys == NULL || keys[0] == NULL) {
 626                 error("sc_get_keys failed");
 627                 goto send;
 628         }
 629         for (i = 0; keys[i] != NULL; i++) {
 630                 k = keys[i];
 631                 version = k->type == KEY_RSA1 ? 1 : 2;
 632                 tab = idtab_lookup(version);
 633                 if (lookup_identity(k, version) == NULL) {
 634                         id = xmalloc(sizeof(Identity));
 635                         id->key = k;
 636                         id->comment = sc_get_key_label(k);
 637                         id->death = death;
 638                         id->confirm = confirm;
 639                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 640                         tab->nentries++;
 641                         success = 1;
 642                 } else {
 643                         key_free(k);
 644                 }
 645                 keys[i] = NULL;
 646         }
 647         xfree(keys);
 648 send:
 649         buffer_put_int(&e->output, 1);
 650         buffer_put_char(&e->output,
 651             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 652 }
 653
 654 static void
 655 process_remove_smartcard_key(SocketEntry *e)
 656 {
 657         char *sc_reader_id = NULL, *pin;
 658         int i, version, success = 0;
 659         Key **keys, *k = NULL;
 660         Identity *id;
 661         Idtab *tab;
 662
 663         sc_reader_id = buffer_get_string(&e->request, NULL);
 664         pin = buffer_get_string(&e->request, NULL);
 665         keys = sc_get_keys(sc_reader_id, pin);
 666         xfree(sc_reader_id);
 667         xfree(pin);
 668
 669         if (keys == NULL || keys[0] == NULL) {
 670                 error("sc_get_keys failed");
 671                 goto send;
 672         }
 673         for (i = 0; keys[i] != NULL; i++) {
 674                 k = keys[i];
 675                 version = k->type == KEY_RSA1 ? 1 : 2;
 676                 if ((id = lookup_identity(k, version)) != NULL) {
 677                         tab = idtab_lookup(version);
 678                         TAILQ_REMOVE(&tab->idlist, id, next);
 679                         tab->nentries--;
 680                         free_identity(id);
 681                         success = 1;
 682                 }
 683                 key_free(k);
 684                 keys[i] = NULL;
 685         }
 686         xfree(keys);
 687 send:
 688         buffer_put_int(&e->output, 1);
 689         buffer_put_char(&e->output,
 690             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 691 }
 692 #endif /* SMARTCARD */
 693
 694 /* dispatch incoming messages */
 695
 696 static void
 697 process_message(SocketEntry *e)
 698 {
 699         u_int msg_len, type;
 700         u_char *cp;
 701
 702         if (buffer_len(&e->input) < 5)
 703                 return;         /* Incomplete message. */
 704         cp = buffer_ptr(&e->input);
 705         msg_len = get_u32(cp);
 706         if (msg_len > 256 * 1024) {
 707                 close_socket(e);
 708                 return;
 709         }
 710         if (buffer_len(&e->input) < msg_len + 4)
 711                 return;
 712
 713         /* move the current input to e->request */
 714         buffer_consume(&e->input, 4);
 715         buffer_clear(&e->request);
 716         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 717         buffer_consume(&e->input, msg_len);
 718         type = buffer_get_char(&e->request);
 719
 720         /* check wheter agent is locked */
 721         if (locked && type != SSH_AGENTC_UNLOCK) {
 722                 buffer_clear(&e->request);
 723                 switch (type) {
 724                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 725                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 726                         /* send empty lists */
 727                         no_identities(e, type);
 728                         break;
 729                 default:
 730                         /* send a fail message for all other request types */
 731                         buffer_put_int(&e->output, 1);
 732                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 733                 }
 734                 return;
 735         }
 736
 737         debug("type %d", type);
 738         switch (type) {
 739         case SSH_AGENTC_LOCK:
 740         case SSH_AGENTC_UNLOCK:
 741                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 742                 break;
 743         /* ssh1 */
 744         case SSH_AGENTC_RSA_CHALLENGE:
 745                 process_authentication_challenge1(e);
 746                 break;
 747         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 748                 process_request_identities(e, 1);
 749                 break;
 750         case SSH_AGENTC_ADD_RSA_IDENTITY:
 751         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 752                 process_add_identity(e, 1);
 753                 break;
 754         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 755                 process_remove_identity(e, 1);
 756                 break;
 757         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 758                 process_remove_all_identities(e, 1);
 759                 break;
 760         /* ssh2 */
 761         case SSH2_AGENTC_SIGN_REQUEST:
 762                 process_sign_request2(e);
 763                 break;
 764         case SSH2_AGENTC_REQUEST_IDENTITIES:
 765                 process_request_identities(e, 2);
 766                 break;
 767         case SSH2_AGENTC_ADD_IDENTITY:
 768         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 769                 process_add_identity(e, 2);
 770                 break;
 771         case SSH2_AGENTC_REMOVE_IDENTITY:
 772                 process_remove_identity(e, 2);
 773                 break;
 774         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 775                 process_remove_all_identities(e, 2);
 776                 break;
 777 #ifdef SMARTCARD
 778         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 779         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 780                 process_add_smartcard_key(e);
 781                 break;
 782         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 783                 process_remove_smartcard_key(e);
 784                 break;
 785 #endif /* SMARTCARD */
 786         default:
 787                 /* Unknown message.  Respond with failure. */
 788                 error("Unknown message %d", type);
 789                 buffer_clear(&e->request);
 790                 buffer_put_int(&e->output, 1);
 791                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 792                 break;
 793         }
 794 }
 795
 796 static void
 797 new_socket(sock_type type, int fd)
 798 {
 799         u_int i, old_alloc, new_alloc;
 800
 801         set_nonblock(fd);
 802
 803         if (fd > max_fd)
 804                 max_fd = fd;
 805
 806         for (i = 0; i < sockets_alloc; i++)
 807                 if (sockets[i].type == AUTH_UNUSED) {
 808                         sockets[i].fd = fd;
 809                         buffer_init(&sockets[i].input);
 810                         buffer_init(&sockets[i].output);
 811                         buffer_init(&sockets[i].request);
 812                         sockets[i].type = type;
 813                         return;
 814                 }
 815         old_alloc = sockets_alloc;
 816         new_alloc = sockets_alloc + 10;
 817         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 818         for (i = old_alloc; i < new_alloc; i++)
 819                 sockets[i].type = AUTH_UNUSED;
 820         sockets_alloc = new_alloc;
 821         sockets[old_alloc].fd = fd;
 822         buffer_init(&sockets[old_alloc].input);
 823         buffer_init(&sockets[old_alloc].output);
 824         buffer_init(&sockets[old_alloc].request);
 825         sockets[old_alloc].type = type;
 826 }
 827
 828 static int
 829 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
 830 {
 831         u_int i, sz;
 832         int n = 0;
 833
 834         for (i = 0; i < sockets_alloc; i++) {
 835                 switch (sockets[i].type) {
 836                 case AUTH_SOCKET:
 837                 case AUTH_CONNECTION:
 838                         n = MAX(n, sockets[i].fd);
 839                         break;
 840                 case AUTH_UNUSED:
 841                         break;
 842                 default:
 843                         fatal("Unknown socket type %d", sockets[i].type);
 844                         break;
 845                 }
 846         }
 847
 848         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 849         if (*fdrp == NULL || sz > *nallocp) {
 850                 if (*fdrp)
 851                         xfree(*fdrp);
 852                 if (*fdwp)
 853                         xfree(*fdwp);
 854                 *fdrp = xmalloc(sz);
 855                 *fdwp = xmalloc(sz);
 856                 *nallocp = sz;
 857         }
 858         if (n < *fdl)
 859                 debug("XXX shrink: %d < %d", n, *fdl);
 860         *fdl = n;
 861         memset(*fdrp, 0, sz);
 862         memset(*fdwp, 0, sz);
 863
 864         for (i = 0; i < sockets_alloc; i++) {
 865                 switch (sockets[i].type) {
 866                 case AUTH_SOCKET:
 867                 case AUTH_CONNECTION:
 868                         FD_SET(sockets[i].fd, *fdrp);
 869                         if (buffer_len(&sockets[i].output) > 0)
 870                                 FD_SET(sockets[i].fd, *fdwp);
 871                         break;
 872                 default:
 873                         break;
 874                 }
 875         }
 876         return (1);
 877 }
 878
 879 static void
 880 after_select(fd_set *readset, fd_set *writeset)
 881 {
 882         struct sockaddr_un sunaddr;
 883         socklen_t slen;
 884         char buf[1024];
 885         int len, sock;
 886         u_int i;
 887         uid_t euid;
 888         gid_t egid;
 889
 890         for (i = 0; i < sockets_alloc; i++)
 891                 switch (sockets[i].type) {
 892                 case AUTH_UNUSED:
 893                         break;
 894                 case AUTH_SOCKET:
 895                         if (FD_ISSET(sockets[i].fd, readset)) {
 896                                 slen = sizeof(sunaddr);
 897                                 sock = accept(sockets[i].fd,
 898                                     (struct sockaddr *)&sunaddr, &slen);
 899                                 if (sock < 0) {
 900                                         error("accept from AUTH_SOCKET: %s",
 901                                             strerror(errno));
 902                                         break;
 903                                 }
 904                                 if (getpeereid(sock, &euid, &egid) < 0) {
 905                                         error("getpeereid %d failed: %s",
 906                                             sock, strerror(errno));
 907                                         close(sock);
 908                                         break;
 909                                 }
 910                                 if ((euid != 0) && (getuid() != euid)) {
 911                                         error("uid mismatch: "
 912                                             "peer euid %u != uid %u",
 913                                             (u_int) euid, (u_int) getuid());
 914                                         close(sock);
 915                                         break;
 916                                 }
 917                                 new_socket(AUTH_CONNECTION, sock);
 918                         }
 919                         break;
 920                 case AUTH_CONNECTION:
 921                         if (buffer_len(&sockets[i].output) > 0 &&
 922                             FD_ISSET(sockets[i].fd, writeset)) {
 923                                 do {
 924                                         len = write(sockets[i].fd,
 925                                             buffer_ptr(&sockets[i].output),
 926                                             buffer_len(&sockets[i].output));
 927                                         if (len == -1 && (errno == EAGAIN ||
 928                                             errno == EINTR))
 929                                                 continue;
 930                                         break;
 931                                 } while (1);
 932                                 if (len <= 0) {
 933                                         close_socket(&sockets[i]);
 934                                         break;
 935                                 }
 936                                 buffer_consume(&sockets[i].output, len);
 937                         }
 938                         if (FD_ISSET(sockets[i].fd, readset)) {
 939                                 do {
 940                                         len = read(sockets[i].fd, buf, sizeof(buf));
 941                                         if (len == -1 && (errno == EAGAIN ||
 942                                             errno == EINTR))
 943                                                 continue;
 944                                         break;
 945                                 } while (1);
 946                                 if (len <= 0) {
 947                                         close_socket(&sockets[i]);
 948                                         break;
 949                                 }
 950                                 buffer_append(&sockets[i].input, buf, len);
 951                                 process_message(&sockets[i]);
 952                         }
 953                         break;
 954                 default:
 955                         fatal("Unknown type %d", sockets[i].type);
 956                 }
 957 }
 958
 959 static void
 960 cleanup_socket(void)
 961 {
 962         if (socket_name[0])
 963                 unlink(socket_name);
 964         if (socket_dir[0])
 965                 rmdir(socket_dir);
 966 }
 967
 968 void
 969 cleanup_exit(int i)
 970 {
 971         cleanup_socket();
 972         _exit(i);
 973 }
 974
 975 /*ARGSUSED*/
 976 static void
 977 cleanup_handler(int sig)
 978 {
 979         cleanup_socket();
 980         _exit(2);
 981 }
 982
 983 /*ARGSUSED*/
 984 static void
 985 check_parent_exists(int sig)
 986 {
 987         int save_errno = errno;
 988
 989         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 990                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 991                 cleanup_handler(sig); /* safe */
 992         }
 993         mysignal(SIGALRM, check_parent_exists);
 994         alarm(10);
 995         errno = save_errno;
 996 }
 997
 998 static void
 999 usage(void)
1000 {
1001         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
1002             __progname);
1003         fprintf(stderr, "Options:\n");
1004         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1005         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1006         fprintf(stderr, "  -k          Kill the current agent.\n");
1007         fprintf(stderr, "  -d          Debug mode.\n");
1008         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1009         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1010         exit(1);
1011 }
1012
1013 int
1014 main(int ac, char **av)
1015 {
1016         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1017         int sock, fd, ch, result, saved_errno;
1018         u_int nalloc;
1019         char *shell, *format, *pidstr, *agentsocket = NULL;
1020         fd_set *readsetp = NULL, *writesetp = NULL;
1021         struct sockaddr_un sunaddr;
1022 #ifdef HAVE_SETRLIMIT
1023         struct rlimit rlim;
1024 #endif
1025         int prev_mask;
1026         extern int optind;
1027         extern char *optarg;
1028         pid_t pid;
1029         char pidstrbuf[1 + 3 * sizeof pid];
1030         struct timeval tv;
1031
1032         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1033         sanitise_stdfd();
1034
1035         /* drop */
1036         setegid(getgid());
1037         setgid(getgid());
1038
1039 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1040         /* Disable ptrace on Linux without sgid bit */
1041         prctl(PR_SET_DUMPABLE, 0);
1042 #endif
1043
1044         SSLeay_add_all_algorithms();
1045
1046         __progname = ssh_get_progname(av[0]);
1047         init_rng();
1048         seed_rng();
1049
1050         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1051                 switch (ch) {
1052                 case 'c':
1053                         if (s_flag)
1054                                 usage();
1055                         c_flag++;
1056                         break;
1057                 case 'k':
1058                         k_flag++;
1059                         break;
1060                 case 's':
1061                         if (c_flag)
1062                                 usage();
1063                         s_flag++;
1064                         break;
1065                 case 'd':
1066                         if (d_flag)
1067                                 usage();
1068                         d_flag++;
1069                         break;
1070                 case 'a':
1071                         agentsocket = optarg;
1072                         break;
1073                 case 't':
1074                         if ((lifetime = convtime(optarg)) == -1) {
1075                                 fprintf(stderr, "Invalid lifetime\n");
1076                                 usage();
1077                         }
1078                         break;
1079                 default:
1080                         usage();
1081                 }
1082         }
1083         ac -= optind;
1084         av += optind;
1085
1086         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1087                 usage();
1088
1089         if (ac == 0 && !c_flag && !s_flag) {
1090                 shell = getenv("SHELL");
1091                 if (shell != NULL &&
1092                     strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1093                         c_flag = 1;
1094         }
1095         if (k_flag) {
1096                 const char *errstr = NULL;
1097
1098                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1099                 if (pidstr == NULL) {
1100                         fprintf(stderr, "%s not set, cannot kill agent\n",
1101                             SSH_AGENTPID_ENV_NAME);
1102                         exit(1);
1103                 }
1104                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1105                 if (errstr) {
1106                         fprintf(stderr,
1107                             "%s=\"%s\", which is not a good PID: %s\n",
1108                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1109                         exit(1);
1110                 }
1111                 if (kill(pid, SIGTERM) == -1) {
1112                         perror("kill");
1113                         exit(1);
1114                 }
1115                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1116                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1117                 printf(format, SSH_AGENTPID_ENV_NAME);
1118                 printf("echo Agent pid %ld killed;\n", (long)pid);
1119                 exit(0);
1120         }
1121         parent_pid = getpid();
1122
1123         if (agentsocket == NULL) {
1124                 /* Create private directory for agent socket */
1125                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1126                 if (mkdtemp(socket_dir) == NULL) {
1127                         perror("mkdtemp: private socket dir");
1128                         exit(1);
1129                 }
1130                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1131                     (long)parent_pid);
1132         } else {
1133                 /* Try to use specified agent socket */
1134                 socket_dir[0] = '\0';
1135                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1136         }
1137
1138         /*
1139          * Create socket early so it will exist before command gets run from
1140          * the parent.
1141          */
1142         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1143         if (sock < 0) {
1144                 perror("socket");
1145                 *socket_name = '\0'; /* Don't unlink any existing file */
1146                 cleanup_exit(1);
1147         }
1148         memset(&sunaddr, 0, sizeof(sunaddr));
1149         sunaddr.sun_family = AF_UNIX;
1150         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1151         prev_mask = umask(0177);
1152         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1153                 perror("bind");
1154                 *socket_name = '\0'; /* Don't unlink any existing file */
1155                 umask(prev_mask);
1156                 cleanup_exit(1);
1157         }
1158         umask(prev_mask);
1159         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1160                 perror("listen");
1161                 cleanup_exit(1);
1162         }
1163
1164         /*
1165          * Fork, and have the parent execute the command, if any, or present
1166          * the socket data.  The child continues as the authentication agent.
1167          */
1168         if (d_flag) {
1169                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1170                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1171                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1172                     SSH_AUTHSOCKET_ENV_NAME);
1173                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1174                 goto skip;
1175         }
1176         pid = fork();
1177         if (pid == -1) {
1178                 perror("fork");
1179                 cleanup_exit(1);
1180         }
1181         if (pid != 0) {         /* Parent - execute the given command. */
1182                 close(sock);
1183                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1184                 if (ac == 0) {
1185                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1186                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1187                             SSH_AUTHSOCKET_ENV_NAME);
1188                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1189                             SSH_AGENTPID_ENV_NAME);
1190                         printf("echo Agent pid %ld;\n", (long)pid);
1191                         exit(0);
1192                 }
1193                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1194                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1195                         perror("setenv");
1196                         exit(1);
1197                 }
1198                 execvp(av[0], av);
1199                 perror(av[0]);
1200                 exit(1);
1201         }
1202         /* child */
1203         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1204
1205         if (setsid() == -1) {
1206                 error("setsid: %s", strerror(errno));
1207                 cleanup_exit(1);
1208         }
1209
1210         (void)chdir("/");
1211         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1212                 /* XXX might close listen socket */
1213                 (void)dup2(fd, STDIN_FILENO);
1214                 (void)dup2(fd, STDOUT_FILENO);
1215                 (void)dup2(fd, STDERR_FILENO);
1216                 if (fd > 2)
1217                         close(fd);
1218         }
1219
1220 #ifdef HAVE_SETRLIMIT
1221         /* deny core dumps, since memory contains unencrypted private keys */
1222         rlim.rlim_cur = rlim.rlim_max = 0;
1223         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1224                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1225                 cleanup_exit(1);
1226         }
1227 #endif
1228
1229 skip:
1230         new_socket(AUTH_SOCKET, sock);
1231         if (ac > 0) {
1232                 mysignal(SIGALRM, check_parent_exists);
1233                 alarm(10);
1234         }
1235         idtab_init();
1236         if (!d_flag)
1237                 signal(SIGINT, SIG_IGN);
1238         signal(SIGPIPE, SIG_IGN);
1239         signal(SIGHUP, cleanup_handler);
1240         signal(SIGTERM, cleanup_handler);
1241         nalloc = 0;
1242
1243         while (1) {
1244                 tv.tv_sec = 10;
1245                 tv.tv_usec = 0;
1246                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1247                 result = select(max_fd + 1, readsetp, writesetp, NULL, &tv);
1248                 saved_errno = errno;
1249                 reaper();       /* remove expired keys */
1250                 if (result < 0) {
1251                         if (saved_errno == EINTR)
1252                                 continue;
1253                         fatal("select: %s", strerror(saved_errno));
1254                 } else if (result > 0)
1255                         after_select(readsetp, writesetp);
1256         }
1257         /* NOTREACHED */
1258 }