crypto/openssh-4/ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.155 2007/03/19 12:16:42 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 u_int parent_alive_interval = 0;
 124
 125 /* pathname and directory for AUTH_SOCKET */
 126 char socket_name[MAXPATHLEN];
 127 char socket_dir[MAXPATHLEN];
 128
 129 /* locking */
 130 int locked = 0;
 131 char *lock_passwd = NULL;
 132
 133 extern char *__progname;
 134
 135 /* Default lifetime (0 == forever) */
 136 static int lifetime = 0;
 137
 138 static void
 139 close_socket(SocketEntry *e)
 140 {
 141         close(e->fd);
 142         e->fd = -1;
 143         e->type = AUTH_UNUSED;
 144         buffer_free(&e->input);
 145         buffer_free(&e->output);
 146         buffer_free(&e->request);
 147 }
 148
 149 static void
 150 idtab_init(void)
 151 {
 152         int i;
 153
 154         for (i = 0; i <=2; i++) {
 155                 TAILQ_INIT(&idtable[i].idlist);
 156                 idtable[i].nentries = 0;
 157         }
 158 }
 159
 160 /* return private key table for requested protocol version */
 161 static Idtab *
 162 idtab_lookup(int version)
 163 {
 164         if (version < 1 || version > 2)
 165                 fatal("internal error, bad protocol version %d", version);
 166         return &idtable[version];
 167 }
 168
 169 static void
 170 free_identity(Identity *id)
 171 {
 172         key_free(id->key);
 173         xfree(id->comment);
 174         xfree(id);
 175 }
 176
 177 /* return matching private key for given public key */
 178 static Identity *
 179 lookup_identity(Key *key, int version)
 180 {
 181         Identity *id;
 182
 183         Idtab *tab = idtab_lookup(version);
 184         TAILQ_FOREACH(id, &tab->idlist, next) {
 185                 if (key_equal(key, id->key))
 186                         return (id);
 187         }
 188         return (NULL);
 189 }
 190
 191 /* Check confirmation of keysign request */
 192 static int
 193 confirm_key(Identity *id)
 194 {
 195         char *p;
 196         int ret = -1;
 197
 198         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 199         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 200             id->comment, p))
 201                 ret = 0;
 202         xfree(p);
 203
 204         return (ret);
 205 }
 206
 207 /* send list of supported public keys to 'client' */
 208 static void
 209 process_request_identities(SocketEntry *e, int version)
 210 {
 211         Idtab *tab = idtab_lookup(version);
 212         Identity *id;
 213         Buffer msg;
 214
 215         buffer_init(&msg);
 216         buffer_put_char(&msg, (version == 1) ?
 217             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 218         buffer_put_int(&msg, tab->nentries);
 219         TAILQ_FOREACH(id, &tab->idlist, next) {
 220                 if (id->key->type == KEY_RSA1) {
 221                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 222                         buffer_put_bignum(&msg, id->key->rsa->e);
 223                         buffer_put_bignum(&msg, id->key->rsa->n);
 224                 } else {
 225                         u_char *blob;
 226                         u_int blen;
 227                         key_to_blob(id->key, &blob, &blen);
 228                         buffer_put_string(&msg, blob, blen);
 229                         xfree(blob);
 230                 }
 231                 buffer_put_cstring(&msg, id->comment);
 232         }
 233         buffer_put_int(&e->output, buffer_len(&msg));
 234         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 235         buffer_free(&msg);
 236 }
 237
 238 /* ssh1 only */
 239 static void
 240 process_authentication_challenge1(SocketEntry *e)
 241 {
 242         u_char buf[32], mdbuf[16], session_id[16];
 243         u_int response_type;
 244         BIGNUM *challenge;
 245         Identity *id;
 246         int i, len;
 247         Buffer msg;
 248         MD5_CTX md;
 249         Key *key;
 250
 251         buffer_init(&msg);
 252         key = key_new(KEY_RSA1);
 253         if ((challenge = BN_new()) == NULL)
 254                 fatal("process_authentication_challenge1: BN_new failed");
 255
 256         (void) buffer_get_int(&e->request);                     /* ignored */
 257         buffer_get_bignum(&e->request, key->rsa->e);
 258         buffer_get_bignum(&e->request, key->rsa->n);
 259         buffer_get_bignum(&e->request, challenge);
 260
 261         /* Only protocol 1.1 is supported */
 262         if (buffer_len(&e->request) == 0)
 263                 goto failure;
 264         buffer_get(&e->request, session_id, 16);
 265         response_type = buffer_get_int(&e->request);
 266         if (response_type != 1)
 267                 goto failure;
 268
 269         id = lookup_identity(key, 1);
 270         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 271                 Key *private = id->key;
 272                 /* Decrypt the challenge using the private key. */
 273                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 274                         goto failure;
 275
 276                 /* The response is MD5 of decrypted challenge plus session id. */
 277                 len = BN_num_bytes(challenge);
 278                 if (len <= 0 || len > 32) {
 279                         logit("process_authentication_challenge: bad challenge length %d", len);
 280                         goto failure;
 281                 }
 282                 memset(buf, 0, 32);
 283                 BN_bn2bin(challenge, buf + 32 - len);
 284                 MD5_Init(&md);
 285                 MD5_Update(&md, buf, 32);
 286                 MD5_Update(&md, session_id, 16);
 287                 MD5_Final(mdbuf, &md);
 288
 289                 /* Send the response. */
 290                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 291                 for (i = 0; i < 16; i++)
 292                         buffer_put_char(&msg, mdbuf[i]);
 293                 goto send;
 294         }
 295
 296 failure:
 297         /* Unknown identity or protocol error.  Send failure. */
 298         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 299 send:
 300         buffer_put_int(&e->output, buffer_len(&msg));
 301         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 302         key_free(key);
 303         BN_clear_free(challenge);
 304         buffer_free(&msg);
 305 }
 306
 307 /* ssh2 only */
 308 static void
 309 process_sign_request2(SocketEntry *e)
 310 {
 311         u_char *blob, *data, *signature = NULL;
 312         u_int blen, dlen, slen = 0;
 313         extern int datafellows;
 314         int ok = -1, flags;
 315         Buffer msg;
 316         Key *key;
 317
 318         datafellows = 0;
 319
 320         blob = buffer_get_string(&e->request, &blen);
 321         data = buffer_get_string(&e->request, &dlen);
 322
 323         flags = buffer_get_int(&e->request);
 324         if (flags & SSH_AGENT_OLD_SIGNATURE)
 325                 datafellows = SSH_BUG_SIGBLOB;
 326
 327         key = key_from_blob(blob, blen);
 328         if (key != NULL) {
 329                 Identity *id = lookup_identity(key, 2);
 330                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 331                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 332                 key_free(key);
 333         }
 334         buffer_init(&msg);
 335         if (ok == 0) {
 336                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 337                 buffer_put_string(&msg, signature, slen);
 338         } else {
 339                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 340         }
 341         buffer_put_int(&e->output, buffer_len(&msg));
 342         buffer_append(&e->output, buffer_ptr(&msg),
 343             buffer_len(&msg));
 344         buffer_free(&msg);
 345         xfree(data);
 346         xfree(blob);
 347         if (signature != NULL)
 348                 xfree(signature);
 349 }
 350
 351 /* shared */
 352 static void
 353 process_remove_identity(SocketEntry *e, int version)
 354 {
 355         u_int blen, bits;
 356         int success = 0;
 357         Key *key = NULL;
 358         u_char *blob;
 359
 360         switch (version) {
 361         case 1:
 362                 key = key_new(KEY_RSA1);
 363                 bits = buffer_get_int(&e->request);
 364                 buffer_get_bignum(&e->request, key->rsa->e);
 365                 buffer_get_bignum(&e->request, key->rsa->n);
 366
 367                 if (bits != key_size(key))
 368                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 369                             key_size(key), bits);
 370                 break;
 371         case 2:
 372                 blob = buffer_get_string(&e->request, &blen);
 373                 key = key_from_blob(blob, blen);
 374                 xfree(blob);
 375                 break;
 376         }
 377         if (key != NULL) {
 378                 Identity *id = lookup_identity(key, version);
 379                 if (id != NULL) {
 380                         /*
 381                          * We have this key.  Free the old key.  Since we
 382                          * don't want to leave empty slots in the middle of
 383                          * the array, we actually free the key there and move
 384                          * all the entries between the empty slot and the end
 385                          * of the array.
 386                          */
 387                         Idtab *tab = idtab_lookup(version);
 388                         if (tab->nentries < 1)
 389                                 fatal("process_remove_identity: "
 390                                     "internal error: tab->nentries %d",
 391                                     tab->nentries);
 392                         TAILQ_REMOVE(&tab->idlist, id, next);
 393                         free_identity(id);
 394                         tab->nentries--;
 395                         success = 1;
 396                 }
 397                 key_free(key);
 398         }
 399         buffer_put_int(&e->output, 1);
 400         buffer_put_char(&e->output,
 401             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 402 }
 403
 404 static void
 405 process_remove_all_identities(SocketEntry *e, int version)
 406 {
 407         Idtab *tab = idtab_lookup(version);
 408         Identity *id;
 409
 410         /* Loop over all identities and clear the keys. */
 411         for (id = TAILQ_FIRST(&tab->idlist); id;
 412             id = TAILQ_FIRST(&tab->idlist)) {
 413                 TAILQ_REMOVE(&tab->idlist, id, next);
 414                 free_identity(id);
 415         }
 416
 417         /* Mark that there are no identities. */
 418         tab->nentries = 0;
 419
 420         /* Send success. */
 421         buffer_put_int(&e->output, 1);
 422         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 423 }
 424
 425 /* removes expired keys and returns number of seconds until the next expiry */
 426 static u_int
 427 reaper(void)
 428 {
 429         u_int deadline = 0, now = time(NULL);
 430         Identity *id, *nxt;
 431         int version;
 432         Idtab *tab;
 433
 434         for (version = 1; version < 3; version++) {
 435                 tab = idtab_lookup(version);
 436                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 437                         nxt = TAILQ_NEXT(id, next);
 438                         if (id->death == 0)
 439                                 continue;
 440                         if (now >= id->death) {
 441                                 debug("expiring key '%s'", id->comment);
 442                                 TAILQ_REMOVE(&tab->idlist, id, next);
 443                                 free_identity(id);
 444                                 tab->nentries--;
 445                         } else
 446                                 deadline = (deadline == 0) ? id->death :
 447                                     MIN(deadline, id->death);
 448                 }
 449         }
 450         if (deadline == 0 || deadline <= now)
 451                 return 0;
 452         else
 453                 return (deadline - now);
 454 }
 455
 456 static void
 457 process_add_identity(SocketEntry *e, int version)
 458 {
 459         Idtab *tab = idtab_lookup(version);
 460         int type, success = 0, death = 0, confirm = 0;
 461         char *type_name, *comment;
 462         Key *k = NULL;
 463
 464         switch (version) {
 465         case 1:
 466                 k = key_new_private(KEY_RSA1);
 467                 (void) buffer_get_int(&e->request);             /* ignored */
 468                 buffer_get_bignum(&e->request, k->rsa->n);
 469                 buffer_get_bignum(&e->request, k->rsa->e);
 470                 buffer_get_bignum(&e->request, k->rsa->d);
 471                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 472
 473                 /* SSH and SSL have p and q swapped */
 474                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 475                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 476
 477                 /* Generate additional parameters */
 478                 rsa_generate_additional_parameters(k->rsa);
 479                 break;
 480         case 2:
 481                 type_name = buffer_get_string(&e->request, NULL);
 482                 type = key_type_from_name(type_name);
 483                 xfree(type_name);
 484                 switch (type) {
 485                 case KEY_DSA:
 486                         k = key_new_private(type);
 487                         buffer_get_bignum2(&e->request, k->dsa->p);
 488                         buffer_get_bignum2(&e->request, k->dsa->q);
 489                         buffer_get_bignum2(&e->request, k->dsa->g);
 490                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 491                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 492                         break;
 493                 case KEY_RSA:
 494                         k = key_new_private(type);
 495                         buffer_get_bignum2(&e->request, k->rsa->n);
 496                         buffer_get_bignum2(&e->request, k->rsa->e);
 497                         buffer_get_bignum2(&e->request, k->rsa->d);
 498                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 499                         buffer_get_bignum2(&e->request, k->rsa->p);
 500                         buffer_get_bignum2(&e->request, k->rsa->q);
 501
 502                         /* Generate additional parameters */
 503                         rsa_generate_additional_parameters(k->rsa);
 504                         break;
 505                 default:
 506                         buffer_clear(&e->request);
 507                         goto send;
 508                 }
 509                 break;
 510         }
 511         /* enable blinding */
 512         switch (k->type) {
 513         case KEY_RSA:
 514         case KEY_RSA1:
 515                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 516                         error("process_add_identity: RSA_blinding_on failed");
 517                         key_free(k);
 518                         goto send;
 519                 }
 520                 break;
 521         }
 522         comment = buffer_get_string(&e->request, NULL);
 523         if (k == NULL) {
 524                 xfree(comment);
 525                 goto send;
 526         }
 527         success = 1;
 528         while (buffer_len(&e->request)) {
 529                 switch (buffer_get_char(&e->request)) {
 530                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 531                         death = time(NULL) + buffer_get_int(&e->request);
 532                         break;
 533                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 534                         confirm = 1;
 535                         break;
 536                 default:
 537                         break;
 538                 }
 539         }
 540         if (lifetime && !death)
 541                 death = time(NULL) + lifetime;
 542         if (lookup_identity(k, version) == NULL) {
 543                 Identity *id = xmalloc(sizeof(Identity));
 544                 id->key = k;
 545                 id->comment = comment;
 546                 id->death = death;
 547                 id->confirm = confirm;
 548                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 549                 /* Increment the number of identities. */
 550                 tab->nentries++;
 551         } else {
 552                 key_free(k);
 553                 xfree(comment);
 554         }
 555 send:
 556         buffer_put_int(&e->output, 1);
 557         buffer_put_char(&e->output,
 558             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 559 }
 560
 561 /* XXX todo: encrypt sensitive data with passphrase */
 562 static void
 563 process_lock_agent(SocketEntry *e, int lock)
 564 {
 565         int success = 0;
 566         char *passwd;
 567
 568         passwd = buffer_get_string(&e->request, NULL);
 569         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 570                 locked = 0;
 571                 memset(lock_passwd, 0, strlen(lock_passwd));
 572                 xfree(lock_passwd);
 573                 lock_passwd = NULL;
 574                 success = 1;
 575         } else if (!locked && lock) {
 576                 locked = 1;
 577                 lock_passwd = xstrdup(passwd);
 578                 success = 1;
 579         }
 580         memset(passwd, 0, strlen(passwd));
 581         xfree(passwd);
 582
 583         buffer_put_int(&e->output, 1);
 584         buffer_put_char(&e->output,
 585             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 586 }
 587
 588 static void
 589 no_identities(SocketEntry *e, u_int type)
 590 {
 591         Buffer msg;
 592
 593         buffer_init(&msg);
 594         buffer_put_char(&msg,
 595             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 596             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 597         buffer_put_int(&msg, 0);
 598         buffer_put_int(&e->output, buffer_len(&msg));
 599         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 600         buffer_free(&msg);
 601 }
 602
 603 #ifdef SMARTCARD
 604 static void
 605 process_add_smartcard_key (SocketEntry *e)
 606 {
 607         char *sc_reader_id = NULL, *pin;
 608         int i, version, success = 0, death = 0, confirm = 0;
 609         Key **keys, *k;
 610         Identity *id;
 611         Idtab *tab;
 612
 613         sc_reader_id = buffer_get_string(&e->request, NULL);
 614         pin = buffer_get_string(&e->request, NULL);
 615
 616         while (buffer_len(&e->request)) {
 617                 switch (buffer_get_char(&e->request)) {
 618                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 619                         death = time(NULL) + buffer_get_int(&e->request);
 620                         break;
 621                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 622                         confirm = 1;
 623                         break;
 624                 default:
 625                         break;
 626                 }
 627         }
 628         if (lifetime && !death)
 629                 death = time(NULL) + lifetime;
 630
 631         keys = sc_get_keys(sc_reader_id, pin);
 632         xfree(sc_reader_id);
 633         xfree(pin);
 634
 635         if (keys == NULL || keys[0] == NULL) {
 636                 error("sc_get_keys failed");
 637                 goto send;
 638         }
 639         for (i = 0; keys[i] != NULL; i++) {
 640                 k = keys[i];
 641                 version = k->type == KEY_RSA1 ? 1 : 2;
 642                 tab = idtab_lookup(version);
 643                 if (lookup_identity(k, version) == NULL) {
 644                         id = xmalloc(sizeof(Identity));
 645                         id->key = k;
 646                         id->comment = sc_get_key_label(k);
 647                         id->death = death;
 648                         id->confirm = confirm;
 649                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 650                         tab->nentries++;
 651                         success = 1;
 652                 } else {
 653                         key_free(k);
 654                 }
 655                 keys[i] = NULL;
 656         }
 657         xfree(keys);
 658 send:
 659         buffer_put_int(&e->output, 1);
 660         buffer_put_char(&e->output,
 661             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 662 }
 663
 664 static void
 665 process_remove_smartcard_key(SocketEntry *e)
 666 {
 667         char *sc_reader_id = NULL, *pin;
 668         int i, version, success = 0;
 669         Key **keys, *k = NULL;
 670         Identity *id;
 671         Idtab *tab;
 672
 673         sc_reader_id = buffer_get_string(&e->request, NULL);
 674         pin = buffer_get_string(&e->request, NULL);
 675         keys = sc_get_keys(sc_reader_id, pin);
 676         xfree(sc_reader_id);
 677         xfree(pin);
 678
 679         if (keys == NULL || keys[0] == NULL) {
 680                 error("sc_get_keys failed");
 681                 goto send;
 682         }
 683         for (i = 0; keys[i] != NULL; i++) {
 684                 k = keys[i];
 685                 version = k->type == KEY_RSA1 ? 1 : 2;
 686                 if ((id = lookup_identity(k, version)) != NULL) {
 687                         tab = idtab_lookup(version);
 688                         TAILQ_REMOVE(&tab->idlist, id, next);
 689                         tab->nentries--;
 690                         free_identity(id);
 691                         success = 1;
 692                 }
 693                 key_free(k);
 694                 keys[i] = NULL;
 695         }
 696         xfree(keys);
 697 send:
 698         buffer_put_int(&e->output, 1);
 699         buffer_put_char(&e->output,
 700             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 701 }
 702 #endif /* SMARTCARD */
 703
 704 /* dispatch incoming messages */
 705
 706 static void
 707 process_message(SocketEntry *e)
 708 {
 709         u_int msg_len, type;
 710         u_char *cp;
 711
 712         if (buffer_len(&e->input) < 5)
 713                 return;         /* Incomplete message. */
 714         cp = buffer_ptr(&e->input);
 715         msg_len = get_u32(cp);
 716         if (msg_len > 256 * 1024) {
 717                 close_socket(e);
 718                 return;
 719         }
 720         if (buffer_len(&e->input) < msg_len + 4)
 721                 return;
 722
 723         /* move the current input to e->request */
 724         buffer_consume(&e->input, 4);
 725         buffer_clear(&e->request);
 726         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 727         buffer_consume(&e->input, msg_len);
 728         type = buffer_get_char(&e->request);
 729
 730         /* check wheter agent is locked */
 731         if (locked && type != SSH_AGENTC_UNLOCK) {
 732                 buffer_clear(&e->request);
 733                 switch (type) {
 734                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 735                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 736                         /* send empty lists */
 737                         no_identities(e, type);
 738                         break;
 739                 default:
 740                         /* send a fail message for all other request types */
 741                         buffer_put_int(&e->output, 1);
 742                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 743                 }
 744                 return;
 745         }
 746
 747         debug("type %d", type);
 748         switch (type) {
 749         case SSH_AGENTC_LOCK:
 750         case SSH_AGENTC_UNLOCK:
 751                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 752                 break;
 753         /* ssh1 */
 754         case SSH_AGENTC_RSA_CHALLENGE:
 755                 process_authentication_challenge1(e);
 756                 break;
 757         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 758                 process_request_identities(e, 1);
 759                 break;
 760         case SSH_AGENTC_ADD_RSA_IDENTITY:
 761         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 762                 process_add_identity(e, 1);
 763                 break;
 764         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 765                 process_remove_identity(e, 1);
 766                 break;
 767         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 768                 process_remove_all_identities(e, 1);
 769                 break;
 770         /* ssh2 */
 771         case SSH2_AGENTC_SIGN_REQUEST:
 772                 process_sign_request2(e);
 773                 break;
 774         case SSH2_AGENTC_REQUEST_IDENTITIES:
 775                 process_request_identities(e, 2);
 776                 break;
 777         case SSH2_AGENTC_ADD_IDENTITY:
 778         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 779                 process_add_identity(e, 2);
 780                 break;
 781         case SSH2_AGENTC_REMOVE_IDENTITY:
 782                 process_remove_identity(e, 2);
 783                 break;
 784         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 785                 process_remove_all_identities(e, 2);
 786                 break;
 787 #ifdef SMARTCARD
 788         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 789         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 790                 process_add_smartcard_key(e);
 791                 break;
 792         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 793                 process_remove_smartcard_key(e);
 794                 break;
 795 #endif /* SMARTCARD */
 796         default:
 797                 /* Unknown message.  Respond with failure. */
 798                 error("Unknown message %d", type);
 799                 buffer_clear(&e->request);
 800                 buffer_put_int(&e->output, 1);
 801                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 802                 break;
 803         }
 804 }
 805
 806 static void
 807 new_socket(sock_type type, int fd)
 808 {
 809         u_int i, old_alloc, new_alloc;
 810
 811         set_nonblock(fd);
 812
 813         if (fd > max_fd)
 814                 max_fd = fd;
 815
 816         for (i = 0; i < sockets_alloc; i++)
 817                 if (sockets[i].type == AUTH_UNUSED) {
 818                         sockets[i].fd = fd;
 819                         buffer_init(&sockets[i].input);
 820                         buffer_init(&sockets[i].output);
 821                         buffer_init(&sockets[i].request);
 822                         sockets[i].type = type;
 823                         return;
 824                 }
 825         old_alloc = sockets_alloc;
 826         new_alloc = sockets_alloc + 10;
 827         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 828         for (i = old_alloc; i < new_alloc; i++)
 829                 sockets[i].type = AUTH_UNUSED;
 830         sockets_alloc = new_alloc;
 831         sockets[old_alloc].fd = fd;
 832         buffer_init(&sockets[old_alloc].input);
 833         buffer_init(&sockets[old_alloc].output);
 834         buffer_init(&sockets[old_alloc].request);
 835         sockets[old_alloc].type = type;
 836 }
 837
 838 static int
 839 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
 840     struct timeval **tvpp)
 841 {
 842         u_int i, sz, deadline;
 843         int n = 0;
 844         static struct timeval tv;
 845
 846         for (i = 0; i < sockets_alloc; i++) {
 847                 switch (sockets[i].type) {
 848                 case AUTH_SOCKET:
 849                 case AUTH_CONNECTION:
 850                         n = MAX(n, sockets[i].fd);
 851                         break;
 852                 case AUTH_UNUSED:
 853                         break;
 854                 default:
 855                         fatal("Unknown socket type %d", sockets[i].type);
 856                         break;
 857                 }
 858         }
 859
 860         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 861         if (*fdrp == NULL || sz > *nallocp) {
 862                 if (*fdrp)
 863                         xfree(*fdrp);
 864                 if (*fdwp)
 865                         xfree(*fdwp);
 866                 *fdrp = xmalloc(sz);
 867                 *fdwp = xmalloc(sz);
 868                 *nallocp = sz;
 869         }
 870         if (n < *fdl)
 871                 debug("XXX shrink: %d < %d", n, *fdl);
 872         *fdl = n;
 873         memset(*fdrp, 0, sz);
 874         memset(*fdwp, 0, sz);
 875
 876         for (i = 0; i < sockets_alloc; i++) {
 877                 switch (sockets[i].type) {
 878                 case AUTH_SOCKET:
 879                 case AUTH_CONNECTION:
 880                         FD_SET(sockets[i].fd, *fdrp);
 881                         if (buffer_len(&sockets[i].output) > 0)
 882                                 FD_SET(sockets[i].fd, *fdwp);
 883                         break;
 884                 default:
 885                         break;
 886                 }
 887         }
 888         deadline = reaper();
 889         if (parent_alive_interval != 0)
 890                 deadline = (deadline == 0) ? parent_alive_interval :
 891                     MIN(deadline, parent_alive_interval);
 892         if (deadline == 0) {
 893                 *tvpp = NULL;
 894         } else {
 895                 tv.tv_sec = deadline;
 896                 tv.tv_usec = 0;
 897                 *tvpp = &tv;
 898         }
 899         return (1);
 900 }
 901
 902 static void
 903 after_select(fd_set *readset, fd_set *writeset)
 904 {
 905         struct sockaddr_un sunaddr;
 906         socklen_t slen;
 907         char buf[1024];
 908         int len, sock;
 909         u_int i;
 910         uid_t euid;
 911         gid_t egid;
 912
 913         for (i = 0; i < sockets_alloc; i++)
 914                 switch (sockets[i].type) {
 915                 case AUTH_UNUSED:
 916                         break;
 917                 case AUTH_SOCKET:
 918                         if (FD_ISSET(sockets[i].fd, readset)) {
 919                                 slen = sizeof(sunaddr);
 920                                 sock = accept(sockets[i].fd,
 921                                     (struct sockaddr *)&sunaddr, &slen);
 922                                 if (sock < 0) {
 923                                         error("accept from AUTH_SOCKET: %s",
 924                                             strerror(errno));
 925                                         break;
 926                                 }
 927                                 if (getpeereid(sock, &euid, &egid) < 0) {
 928                                         error("getpeereid %d failed: %s",
 929                                             sock, strerror(errno));
 930                                         close(sock);
 931                                         break;
 932                                 }
 933                                 if ((euid != 0) && (getuid() != euid)) {
 934                                         error("uid mismatch: "
 935                                             "peer euid %u != uid %u",
 936                                             (u_int) euid, (u_int) getuid());
 937                                         close(sock);
 938                                         break;
 939                                 }
 940                                 new_socket(AUTH_CONNECTION, sock);
 941                         }
 942                         break;
 943                 case AUTH_CONNECTION:
 944                         if (buffer_len(&sockets[i].output) > 0 &&
 945                             FD_ISSET(sockets[i].fd, writeset)) {
 946                                 do {
 947                                         len = write(sockets[i].fd,
 948                                             buffer_ptr(&sockets[i].output),
 949                                             buffer_len(&sockets[i].output));
 950                                         if (len == -1 && (errno == EAGAIN ||
 951                                             errno == EINTR))
 952                                                 continue;
 953                                         break;
 954                                 } while (1);
 955                                 if (len <= 0) {
 956                                         close_socket(&sockets[i]);
 957                                         break;
 958                                 }
 959                                 buffer_consume(&sockets[i].output, len);
 960                         }
 961                         if (FD_ISSET(sockets[i].fd, readset)) {
 962                                 do {
 963                                         len = read(sockets[i].fd, buf, sizeof(buf));
 964                                         if (len == -1 && (errno == EAGAIN ||
 965                                             errno == EINTR))
 966                                                 continue;
 967                                         break;
 968                                 } while (1);
 969                                 if (len <= 0) {
 970                                         close_socket(&sockets[i]);
 971                                         break;
 972                                 }
 973                                 buffer_append(&sockets[i].input, buf, len);
 974                                 process_message(&sockets[i]);
 975                         }
 976                         break;
 977                 default:
 978                         fatal("Unknown type %d", sockets[i].type);
 979                 }
 980 }
 981
 982 static void
 983 cleanup_socket(void)
 984 {
 985         if (socket_name[0])
 986                 unlink(socket_name);
 987         if (socket_dir[0])
 988                 rmdir(socket_dir);
 989 }
 990
 991 void
 992 cleanup_exit(int i)
 993 {
 994         cleanup_socket();
 995         _exit(i);
 996 }
 997
 998 /*ARGSUSED*/
 999 static void
1000 cleanup_handler(int sig)
1001 {
1002         cleanup_socket();
1003         _exit(2);
1004 }
1005
1006 static void
1007 check_parent_exists(void)
1008 {
1009         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
1010                 /* printf("Parent has died - Authentication agent exiting.\n"); */
1011                 cleanup_socket();
1012                 _exit(2);
1013         }
1014 }
1015
1016 static void
1017 usage(void)
1018 {
1019         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
1020             __progname);
1021         fprintf(stderr, "Options:\n");
1022         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1023         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1024         fprintf(stderr, "  -k          Kill the current agent.\n");
1025         fprintf(stderr, "  -d          Debug mode.\n");
1026         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1027         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1028         exit(1);
1029 }
1030
1031 int
1032 main(int ac, char **av)
1033 {
1034         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1035         int sock, fd, ch, result, saved_errno;
1036         u_int nalloc;
1037         char *shell, *format, *pidstr, *agentsocket = NULL;
1038         fd_set *readsetp = NULL, *writesetp = NULL;
1039         struct sockaddr_un sunaddr;
1040 #ifdef HAVE_SETRLIMIT
1041         struct rlimit rlim;
1042 #endif
1043         int prev_mask;
1044         extern int optind;
1045         extern char *optarg;
1046         pid_t pid;
1047         char pidstrbuf[1 + 3 * sizeof pid];
1048         struct timeval *tvp = NULL;
1049
1050         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1051         sanitise_stdfd();
1052
1053         /* drop */
1054         setegid(getgid());
1055         setgid(getgid());
1056
1057 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1058         /* Disable ptrace on Linux without sgid bit */
1059         prctl(PR_SET_DUMPABLE, 0);
1060 #endif
1061
1062         SSLeay_add_all_algorithms();
1063
1064         __progname = ssh_get_progname(av[0]);
1065         init_rng();
1066         seed_rng();
1067
1068         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1069                 switch (ch) {
1070                 case 'c':
1071                         if (s_flag)
1072                                 usage();
1073                         c_flag++;
1074                         break;
1075                 case 'k':
1076                         k_flag++;
1077                         break;
1078                 case 's':
1079                         if (c_flag)
1080                                 usage();
1081                         s_flag++;
1082                         break;
1083                 case 'd':
1084                         if (d_flag)
1085                                 usage();
1086                         d_flag++;
1087                         break;
1088                 case 'a':
1089                         agentsocket = optarg;
1090                         break;
1091                 case 't':
1092                         if ((lifetime = convtime(optarg)) == -1) {
1093                                 fprintf(stderr, "Invalid lifetime\n");
1094                                 usage();
1095                         }
1096                         break;
1097                 default:
1098                         usage();
1099                 }
1100         }
1101         ac -= optind;
1102         av += optind;
1103
1104         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1105                 usage();
1106
1107         if (ac == 0 && !c_flag && !s_flag) {
1108                 shell = getenv("SHELL");
1109                 if (shell != NULL &&
1110                     strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1111                         c_flag = 1;
1112         }
1113         if (k_flag) {
1114                 const char *errstr = NULL;
1115
1116                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1117                 if (pidstr == NULL) {
1118                         fprintf(stderr, "%s not set, cannot kill agent\n",
1119                             SSH_AGENTPID_ENV_NAME);
1120                         exit(1);
1121                 }
1122                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1123                 if (errstr) {
1124                         fprintf(stderr,
1125                             "%s=\"%s\", which is not a good PID: %s\n",
1126                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1127                         exit(1);
1128                 }
1129                 if (kill(pid, SIGTERM) == -1) {
1130                         perror("kill");
1131                         exit(1);
1132                 }
1133                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1134                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1135                 printf(format, SSH_AGENTPID_ENV_NAME);
1136                 printf("echo Agent pid %ld killed;\n", (long)pid);
1137                 exit(0);
1138         }
1139         parent_pid = getpid();
1140
1141         if (agentsocket == NULL) {
1142                 /* Create private directory for agent socket */
1143                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1144                 if (mkdtemp(socket_dir) == NULL) {
1145                         perror("mkdtemp: private socket dir");
1146                         exit(1);
1147                 }
1148                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1149                     (long)parent_pid);
1150         } else {
1151                 /* Try to use specified agent socket */
1152                 socket_dir[0] = '\0';
1153                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1154         }
1155
1156         /*
1157          * Create socket early so it will exist before command gets run from
1158          * the parent.
1159          */
1160         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1161         if (sock < 0) {
1162                 perror("socket");
1163                 *socket_name = '\0'; /* Don't unlink any existing file */
1164                 cleanup_exit(1);
1165         }
1166         memset(&sunaddr, 0, sizeof(sunaddr));
1167         sunaddr.sun_family = AF_UNIX;
1168         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1169         prev_mask = umask(0177);
1170         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1171                 perror("bind");
1172                 *socket_name = '\0'; /* Don't unlink any existing file */
1173                 umask(prev_mask);
1174                 cleanup_exit(1);
1175         }
1176         umask(prev_mask);
1177         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1178                 perror("listen");
1179                 cleanup_exit(1);
1180         }
1181
1182         /*
1183          * Fork, and have the parent execute the command, if any, or present
1184          * the socket data.  The child continues as the authentication agent.
1185          */
1186         if (d_flag) {
1187                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1188                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1189                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1190                     SSH_AUTHSOCKET_ENV_NAME);
1191                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1192                 goto skip;
1193         }
1194         pid = fork();
1195         if (pid == -1) {
1196                 perror("fork");
1197                 cleanup_exit(1);
1198         }
1199         if (pid != 0) {         /* Parent - execute the given command. */
1200                 close(sock);
1201                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1202                 if (ac == 0) {
1203                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1204                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1205                             SSH_AUTHSOCKET_ENV_NAME);
1206                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1207                             SSH_AGENTPID_ENV_NAME);
1208                         printf("echo Agent pid %ld;\n", (long)pid);
1209                         exit(0);
1210                 }
1211                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1212                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1213                         perror("setenv");
1214                         exit(1);
1215                 }
1216                 execvp(av[0], av);
1217                 perror(av[0]);
1218                 exit(1);
1219         }
1220         /* child */
1221         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1222
1223         if (setsid() == -1) {
1224                 error("setsid: %s", strerror(errno));
1225                 cleanup_exit(1);
1226         }
1227
1228         (void)chdir("/");
1229         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1230                 /* XXX might close listen socket */
1231                 (void)dup2(fd, STDIN_FILENO);
1232                 (void)dup2(fd, STDOUT_FILENO);
1233                 (void)dup2(fd, STDERR_FILENO);
1234                 if (fd > 2)
1235                         close(fd);
1236         }
1237
1238 #ifdef HAVE_SETRLIMIT
1239         /* deny core dumps, since memory contains unencrypted private keys */
1240         rlim.rlim_cur = rlim.rlim_max = 0;
1241         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1242                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1243                 cleanup_exit(1);
1244         }
1245 #endif
1246
1247 skip:
1248         new_socket(AUTH_SOCKET, sock);
1249         if (ac > 0)
1250                 parent_alive_interval = 10;
1251         idtab_init();
1252         if (!d_flag)
1253                 signal(SIGINT, SIG_IGN);
1254         signal(SIGPIPE, SIG_IGN);
1255         signal(SIGHUP, cleanup_handler);
1256         signal(SIGTERM, cleanup_handler);
1257         nalloc = 0;
1258
1259         while (1) {
1260                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1261                 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1262                 saved_errno = errno;
1263                 if (parent_alive_interval != 0)
1264                         check_parent_exists();
1265                 (void) reaper();        /* remove expired keys */
1266                 if (result < 0) {
1267                         if (saved_errno == EINTR)
1268                                 continue;
1269                         fatal("select: %s", strerror(saved_errno));
1270                 } else if (result > 0)
1271                         after_select(readsetp, writesetp);
1272         }
1273         /* NOTREACHED */
1274 }