crypto/openssh-3.8.1p1/ssh-agent.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * The authentication agent program.
   6  *
   7  * As far as I am concerned, the code I have written for this software
   8  * can be used freely for any purpose.  Any derived versions of this
   9  * software must be clearly marked as such, and if the derived work is
  10  * incompatible with the protocol description in the RFC file, it must be
  11  * called by a name other than "ssh" or "Secure Shell".
  12  *
  13  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  14  *
  15  * Redistribution and use in source and binary forms, with or without
  16  * modification, are permitted provided that the following conditions
  17  * are met:
  18  * 1. Redistributions of source code must retain the above copyright
  19  *    notice, this list of conditions and the following disclaimer.
  20  * 2. Redistributions in binary form must reproduce the above copyright
  21  *    notice, this list of conditions and the following disclaimer in the
  22  *    documentation and/or other materials provided with the distribution.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  27  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  28  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  29  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  30  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  31  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  32  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  33  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 #include "includes.h"
  37 #include "openbsd-compat/sys-queue.h"
  38 RCSID("$OpenBSD: ssh-agent.c,v 1.117 2003/12/02 17:01:15 markus Exp $");
  39
  40 #include <openssl/evp.h>
  41 #include <openssl/md5.h>
  42
  43 #include "ssh.h"
  44 #include "rsa.h"
  45 #include "buffer.h"
  46 #include "bufaux.h"
  47 #include "xmalloc.h"
  48 #include "getput.h"
  49 #include "key.h"
  50 #include "authfd.h"
  51 #include "compat.h"
  52 #include "log.h"
  53 #include "readpass.h"
  54 #include "misc.h"
  55
  56 #ifdef SMARTCARD
  57 #include "scard.h"
  58 #endif
  59
  60 #if defined(HAVE_SYS_PRCTL_H)
  61 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  62 #endif
  63
  64 typedef enum {
  65         AUTH_UNUSED,
  66         AUTH_SOCKET,
  67         AUTH_CONNECTION
  68 } sock_type;
  69
  70 typedef struct {
  71         int fd;
  72         sock_type type;
  73         Buffer input;
  74         Buffer output;
  75         Buffer request;
  76 } SocketEntry;
  77
  78 u_int sockets_alloc = 0;
  79 SocketEntry *sockets = NULL;
  80
  81 typedef struct identity {
  82         TAILQ_ENTRY(identity) next;
  83         Key *key;
  84         char *comment;
  85         u_int death;
  86         u_int confirm;
  87 } Identity;
  88
  89 typedef struct {
  90         int nentries;
  91         TAILQ_HEAD(idqueue, identity) idlist;
  92 } Idtab;
  93
  94 /* private key table, one per protocol version */
  95 Idtab idtable[3];
  96
  97 int max_fd = 0;
  98
  99 /* pid of shell == parent of agent */
 100 pid_t parent_pid = -1;
 101
 102 /* pathname and directory for AUTH_SOCKET */
 103 char socket_name[1024];
 104 char socket_dir[1024];
 105
 106 /* locking */
 107 int locked = 0;
 108 char *lock_passwd = NULL;
 109
 110 #ifdef HAVE___PROGNAME
 111 extern char *__progname;
 112 #else
 113 char *__progname;
 114 #endif
 115
 116 /* Default lifetime (0 == forever) */
 117 static int lifetime = 0;
 118
 119 static void
 120 close_socket(SocketEntry *e)
 121 {
 122         close(e->fd);
 123         e->fd = -1;
 124         e->type = AUTH_UNUSED;
 125         buffer_free(&e->input);
 126         buffer_free(&e->output);
 127         buffer_free(&e->request);
 128 }
 129
 130 static void
 131 idtab_init(void)
 132 {
 133         int i;
 134
 135         for (i = 0; i <=2; i++) {
 136                 TAILQ_INIT(&idtable[i].idlist);
 137                 idtable[i].nentries = 0;
 138         }
 139 }
 140
 141 /* return private key table for requested protocol version */
 142 static Idtab *
 143 idtab_lookup(int version)
 144 {
 145         if (version < 1 || version > 2)
 146                 fatal("internal error, bad protocol version %d", version);
 147         return &idtable[version];
 148 }
 149
 150 static void
 151 free_identity(Identity *id)
 152 {
 153         key_free(id->key);
 154         xfree(id->comment);
 155         xfree(id);
 156 }
 157
 158 /* return matching private key for given public key */
 159 static Identity *
 160 lookup_identity(Key *key, int version)
 161 {
 162         Identity *id;
 163
 164         Idtab *tab = idtab_lookup(version);
 165         TAILQ_FOREACH(id, &tab->idlist, next) {
 166                 if (key_equal(key, id->key))
 167                         return (id);
 168         }
 169         return (NULL);
 170 }
 171
 172 /* Check confirmation of keysign request */
 173 static int
 174 confirm_key(Identity *id)
 175 {
 176         char *p, prompt[1024];
 177         int ret = -1;
 178
 179         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 180         snprintf(prompt, sizeof(prompt), "Allow use of key %s?\n"
 181             "Key fingerprint %s.", id->comment, p);
 182         xfree(p);
 183         p = read_passphrase(prompt, RP_ALLOW_EOF);
 184         if (p != NULL) {
 185                 /*
 186                  * Accept empty responses and responses consisting
 187                  * of the word "yes" as affirmative.
 188                  */
 189                 if (*p == '\0' || *p == '\n' || strcasecmp(p, "yes") == 0)
 190                         ret = 0;
 191                 xfree(p);
 192         }
 193         return (ret);
 194 }
 195
 196 /* send list of supported public keys to 'client' */
 197 static void
 198 process_request_identities(SocketEntry *e, int version)
 199 {
 200         Idtab *tab = idtab_lookup(version);
 201         Identity *id;
 202         Buffer msg;
 203
 204         buffer_init(&msg);
 205         buffer_put_char(&msg, (version == 1) ?
 206             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 207         buffer_put_int(&msg, tab->nentries);
 208         TAILQ_FOREACH(id, &tab->idlist, next) {
 209                 if (id->key->type == KEY_RSA1) {
 210                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 211                         buffer_put_bignum(&msg, id->key->rsa->e);
 212                         buffer_put_bignum(&msg, id->key->rsa->n);
 213                 } else {
 214                         u_char *blob;
 215                         u_int blen;
 216                         key_to_blob(id->key, &blob, &blen);
 217                         buffer_put_string(&msg, blob, blen);
 218                         xfree(blob);
 219                 }
 220                 buffer_put_cstring(&msg, id->comment);
 221         }
 222         buffer_put_int(&e->output, buffer_len(&msg));
 223         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 224         buffer_free(&msg);
 225 }
 226
 227 /* ssh1 only */
 228 static void
 229 process_authentication_challenge1(SocketEntry *e)
 230 {
 231         u_char buf[32], mdbuf[16], session_id[16];
 232         u_int response_type;
 233         BIGNUM *challenge;
 234         Identity *id;
 235         int i, len;
 236         Buffer msg;
 237         MD5_CTX md;
 238         Key *key;
 239
 240         buffer_init(&msg);
 241         key = key_new(KEY_RSA1);
 242         if ((challenge = BN_new()) == NULL)
 243                 fatal("process_authentication_challenge1: BN_new failed");
 244
 245         (void) buffer_get_int(&e->request);                     /* ignored */
 246         buffer_get_bignum(&e->request, key->rsa->e);
 247         buffer_get_bignum(&e->request, key->rsa->n);
 248         buffer_get_bignum(&e->request, challenge);
 249
 250         /* Only protocol 1.1 is supported */
 251         if (buffer_len(&e->request) == 0)
 252                 goto failure;
 253         buffer_get(&e->request, session_id, 16);
 254         response_type = buffer_get_int(&e->request);
 255         if (response_type != 1)
 256                 goto failure;
 257
 258         id = lookup_identity(key, 1);
 259         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 260                 Key *private = id->key;
 261                 /* Decrypt the challenge using the private key. */
 262                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 263                         goto failure;
 264
 265                 /* The response is MD5 of decrypted challenge plus session id. */
 266                 len = BN_num_bytes(challenge);
 267                 if (len <= 0 || len > 32) {
 268                         logit("process_authentication_challenge: bad challenge length %d", len);
 269                         goto failure;
 270                 }
 271                 memset(buf, 0, 32);
 272                 BN_bn2bin(challenge, buf + 32 - len);
 273                 MD5_Init(&md);
 274                 MD5_Update(&md, buf, 32);
 275                 MD5_Update(&md, session_id, 16);
 276                 MD5_Final(mdbuf, &md);
 277
 278                 /* Send the response. */
 279                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 280                 for (i = 0; i < 16; i++)
 281                         buffer_put_char(&msg, mdbuf[i]);
 282                 goto send;
 283         }
 284
 285 failure:
 286         /* Unknown identity or protocol error.  Send failure. */
 287         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 288 send:
 289         buffer_put_int(&e->output, buffer_len(&msg));
 290         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 291         key_free(key);
 292         BN_clear_free(challenge);
 293         buffer_free(&msg);
 294 }
 295
 296 /* ssh2 only */
 297 static void
 298 process_sign_request2(SocketEntry *e)
 299 {
 300         u_char *blob, *data, *signature = NULL;
 301         u_int blen, dlen, slen = 0;
 302         extern int datafellows;
 303         int ok = -1, flags;
 304         Buffer msg;
 305         Key *key;
 306
 307         datafellows = 0;
 308
 309         blob = buffer_get_string(&e->request, &blen);
 310         data = buffer_get_string(&e->request, &dlen);
 311
 312         flags = buffer_get_int(&e->request);
 313         if (flags & SSH_AGENT_OLD_SIGNATURE)
 314                 datafellows = SSH_BUG_SIGBLOB;
 315
 316         key = key_from_blob(blob, blen);
 317         if (key != NULL) {
 318                 Identity *id = lookup_identity(key, 2);
 319                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 320                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 321         }
 322         key_free(key);
 323         buffer_init(&msg);
 324         if (ok == 0) {
 325                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 326                 buffer_put_string(&msg, signature, slen);
 327         } else {
 328                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 329         }
 330         buffer_put_int(&e->output, buffer_len(&msg));
 331         buffer_append(&e->output, buffer_ptr(&msg),
 332             buffer_len(&msg));
 333         buffer_free(&msg);
 334         xfree(data);
 335         xfree(blob);
 336         if (signature != NULL)
 337                 xfree(signature);
 338 }
 339
 340 /* shared */
 341 static void
 342 process_remove_identity(SocketEntry *e, int version)
 343 {
 344         u_int blen, bits;
 345         int success = 0;
 346         Key *key = NULL;
 347         u_char *blob;
 348
 349         switch (version) {
 350         case 1:
 351                 key = key_new(KEY_RSA1);
 352                 bits = buffer_get_int(&e->request);
 353                 buffer_get_bignum(&e->request, key->rsa->e);
 354                 buffer_get_bignum(&e->request, key->rsa->n);
 355
 356                 if (bits != key_size(key))
 357                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 358                             key_size(key), bits);
 359                 break;
 360         case 2:
 361                 blob = buffer_get_string(&e->request, &blen);
 362                 key = key_from_blob(blob, blen);
 363                 xfree(blob);
 364                 break;
 365         }
 366         if (key != NULL) {
 367                 Identity *id = lookup_identity(key, version);
 368                 if (id != NULL) {
 369                         /*
 370                          * We have this key.  Free the old key.  Since we
 371                          * don\'t want to leave empty slots in the middle of
 372                          * the array, we actually free the key there and move
 373                          * all the entries between the empty slot and the end
 374                          * of the array.
 375                          */
 376                         Idtab *tab = idtab_lookup(version);
 377                         if (tab->nentries < 1)
 378                                 fatal("process_remove_identity: "
 379                                     "internal error: tab->nentries %d",
 380                                     tab->nentries);
 381                         TAILQ_REMOVE(&tab->idlist, id, next);
 382                         free_identity(id);
 383                         tab->nentries--;
 384                         success = 1;
 385                 }
 386                 key_free(key);
 387         }
 388         buffer_put_int(&e->output, 1);
 389         buffer_put_char(&e->output,
 390             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 391 }
 392
 393 static void
 394 process_remove_all_identities(SocketEntry *e, int version)
 395 {
 396         Idtab *tab = idtab_lookup(version);
 397         Identity *id;
 398
 399         /* Loop over all identities and clear the keys. */
 400         for (id = TAILQ_FIRST(&tab->idlist); id;
 401             id = TAILQ_FIRST(&tab->idlist)) {
 402                 TAILQ_REMOVE(&tab->idlist, id, next);
 403                 free_identity(id);
 404         }
 405
 406         /* Mark that there are no identities. */
 407         tab->nentries = 0;
 408
 409         /* Send success. */
 410         buffer_put_int(&e->output, 1);
 411         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 412 }
 413
 414 static void
 415 reaper(void)
 416 {
 417         u_int now = time(NULL);
 418         Identity *id, *nxt;
 419         int version;
 420         Idtab *tab;
 421
 422         for (version = 1; version < 3; version++) {
 423                 tab = idtab_lookup(version);
 424                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 425                         nxt = TAILQ_NEXT(id, next);
 426                         if (id->death != 0 && now >= id->death) {
 427                                 TAILQ_REMOVE(&tab->idlist, id, next);
 428                                 free_identity(id);
 429                                 tab->nentries--;
 430                         }
 431                 }
 432         }
 433 }
 434
 435 static void
 436 process_add_identity(SocketEntry *e, int version)
 437 {
 438         Idtab *tab = idtab_lookup(version);
 439         int type, success = 0, death = 0, confirm = 0;
 440         char *type_name, *comment;
 441         Key *k = NULL;
 442
 443         switch (version) {
 444         case 1:
 445                 k = key_new_private(KEY_RSA1);
 446                 (void) buffer_get_int(&e->request);             /* ignored */
 447                 buffer_get_bignum(&e->request, k->rsa->n);
 448                 buffer_get_bignum(&e->request, k->rsa->e);
 449                 buffer_get_bignum(&e->request, k->rsa->d);
 450                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 451
 452                 /* SSH and SSL have p and q swapped */
 453                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 454                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 455
 456                 /* Generate additional parameters */
 457                 rsa_generate_additional_parameters(k->rsa);
 458                 break;
 459         case 2:
 460                 type_name = buffer_get_string(&e->request, NULL);
 461                 type = key_type_from_name(type_name);
 462                 xfree(type_name);
 463                 switch (type) {
 464                 case KEY_DSA:
 465                         k = key_new_private(type);
 466                         buffer_get_bignum2(&e->request, k->dsa->p);
 467                         buffer_get_bignum2(&e->request, k->dsa->q);
 468                         buffer_get_bignum2(&e->request, k->dsa->g);
 469                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 470                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 471                         break;
 472                 case KEY_RSA:
 473                         k = key_new_private(type);
 474                         buffer_get_bignum2(&e->request, k->rsa->n);
 475                         buffer_get_bignum2(&e->request, k->rsa->e);
 476                         buffer_get_bignum2(&e->request, k->rsa->d);
 477                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 478                         buffer_get_bignum2(&e->request, k->rsa->p);
 479                         buffer_get_bignum2(&e->request, k->rsa->q);
 480
 481                         /* Generate additional parameters */
 482                         rsa_generate_additional_parameters(k->rsa);
 483                         break;
 484                 default:
 485                         buffer_clear(&e->request);
 486                         goto send;
 487                 }
 488                 break;
 489         }
 490         /* enable blinding */
 491         switch (k->type) {
 492         case KEY_RSA:
 493         case KEY_RSA1:
 494                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 495                         error("process_add_identity: RSA_blinding_on failed");
 496                         key_free(k);
 497                         goto send;
 498                 }
 499                 break;
 500         }
 501         comment = buffer_get_string(&e->request, NULL);
 502         if (k == NULL) {
 503                 xfree(comment);
 504                 goto send;
 505         }
 506         success = 1;
 507         while (buffer_len(&e->request)) {
 508                 switch (buffer_get_char(&e->request)) {
 509                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 510                         death = time(NULL) + buffer_get_int(&e->request);
 511                         break;
 512                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 513                         confirm = 1;
 514                         break;
 515                 default:
 516                         break;
 517                 }
 518         }
 519         if (lifetime && !death)
 520                 death = time(NULL) + lifetime;
 521         if (lookup_identity(k, version) == NULL) {
 522                 Identity *id = xmalloc(sizeof(Identity));
 523                 id->key = k;
 524                 id->comment = comment;
 525                 id->death = death;
 526                 id->confirm = confirm;
 527                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 528                 /* Increment the number of identities. */
 529                 tab->nentries++;
 530         } else {
 531                 key_free(k);
 532                 xfree(comment);
 533         }
 534 send:
 535         buffer_put_int(&e->output, 1);
 536         buffer_put_char(&e->output,
 537             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 538 }
 539
 540 /* XXX todo: encrypt sensitive data with passphrase */
 541 static void
 542 process_lock_agent(SocketEntry *e, int lock)
 543 {
 544         int success = 0;
 545         char *passwd;
 546
 547         passwd = buffer_get_string(&e->request, NULL);
 548         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 549                 locked = 0;
 550                 memset(lock_passwd, 0, strlen(lock_passwd));
 551                 xfree(lock_passwd);
 552                 lock_passwd = NULL;
 553                 success = 1;
 554         } else if (!locked && lock) {
 555                 locked = 1;
 556                 lock_passwd = xstrdup(passwd);
 557                 success = 1;
 558         }
 559         memset(passwd, 0, strlen(passwd));
 560         xfree(passwd);
 561
 562         buffer_put_int(&e->output, 1);
 563         buffer_put_char(&e->output,
 564             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 565 }
 566
 567 static void
 568 no_identities(SocketEntry *e, u_int type)
 569 {
 570         Buffer msg;
 571
 572         buffer_init(&msg);
 573         buffer_put_char(&msg,
 574             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 575             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 576         buffer_put_int(&msg, 0);
 577         buffer_put_int(&e->output, buffer_len(&msg));
 578         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 579         buffer_free(&msg);
 580 }
 581
 582 #ifdef SMARTCARD
 583 static void
 584 process_add_smartcard_key (SocketEntry *e)
 585 {
 586         char *sc_reader_id = NULL, *pin;
 587         int i, version, success = 0, death = 0, confirm = 0;
 588         Key **keys, *k;
 589         Identity *id;
 590         Idtab *tab;
 591
 592         sc_reader_id = buffer_get_string(&e->request, NULL);
 593         pin = buffer_get_string(&e->request, NULL);
 594
 595         while (buffer_len(&e->request)) {
 596                 switch (buffer_get_char(&e->request)) {
 597                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 598                         death = time(NULL) + buffer_get_int(&e->request);
 599                         break;
 600                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 601                         confirm = 1;
 602                         break;
 603                 default:
 604                         break;
 605                 }
 606         }
 607         if (lifetime && !death)
 608                 death = time(NULL) + lifetime;
 609
 610         keys = sc_get_keys(sc_reader_id, pin);
 611         xfree(sc_reader_id);
 612         xfree(pin);
 613
 614         if (keys == NULL || keys[0] == NULL) {
 615                 error("sc_get_keys failed");
 616                 goto send;
 617         }
 618         for (i = 0; keys[i] != NULL; i++) {
 619                 k = keys[i];
 620                 version = k->type == KEY_RSA1 ? 1 : 2;
 621                 tab = idtab_lookup(version);
 622                 if (lookup_identity(k, version) == NULL) {
 623                         id = xmalloc(sizeof(Identity));
 624                         id->key = k;
 625                         id->comment = sc_get_key_label(k);
 626                         id->death = death;
 627                         id->confirm = confirm;
 628                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 629                         tab->nentries++;
 630                         success = 1;
 631                 } else {
 632                         key_free(k);
 633                 }
 634                 keys[i] = NULL;
 635         }
 636         xfree(keys);
 637 send:
 638         buffer_put_int(&e->output, 1);
 639         buffer_put_char(&e->output,
 640             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 641 }
 642
 643 static void
 644 process_remove_smartcard_key(SocketEntry *e)
 645 {
 646         char *sc_reader_id = NULL, *pin;
 647         int i, version, success = 0;
 648         Key **keys, *k = NULL;
 649         Identity *id;
 650         Idtab *tab;
 651
 652         sc_reader_id = buffer_get_string(&e->request, NULL);
 653         pin = buffer_get_string(&e->request, NULL);
 654         keys = sc_get_keys(sc_reader_id, pin);
 655         xfree(sc_reader_id);
 656         xfree(pin);
 657
 658         if (keys == NULL || keys[0] == NULL) {
 659                 error("sc_get_keys failed");
 660                 goto send;
 661         }
 662         for (i = 0; keys[i] != NULL; i++) {
 663                 k = keys[i];
 664                 version = k->type == KEY_RSA1 ? 1 : 2;
 665                 if ((id = lookup_identity(k, version)) != NULL) {
 666                         tab = idtab_lookup(version);
 667                         TAILQ_REMOVE(&tab->idlist, id, next);
 668                         tab->nentries--;
 669                         free_identity(id);
 670                         success = 1;
 671                 }
 672                 key_free(k);
 673                 keys[i] = NULL;
 674         }
 675         xfree(keys);
 676 send:
 677         buffer_put_int(&e->output, 1);
 678         buffer_put_char(&e->output,
 679             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 680 }
 681 #endif /* SMARTCARD */
 682
 683 /* dispatch incoming messages */
 684
 685 static void
 686 process_message(SocketEntry *e)
 687 {
 688         u_int msg_len, type;
 689         u_char *cp;
 690
 691         /* kill dead keys */
 692         reaper();
 693
 694         if (buffer_len(&e->input) < 5)
 695                 return;         /* Incomplete message. */
 696         cp = buffer_ptr(&e->input);
 697         msg_len = GET_32BIT(cp);
 698         if (msg_len > 256 * 1024) {
 699                 close_socket(e);
 700                 return;
 701         }
 702         if (buffer_len(&e->input) < msg_len + 4)
 703                 return;
 704
 705         /* move the current input to e->request */
 706         buffer_consume(&e->input, 4);
 707         buffer_clear(&e->request);
 708         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 709         buffer_consume(&e->input, msg_len);
 710         type = buffer_get_char(&e->request);
 711
 712         /* check wheter agent is locked */
 713         if (locked && type != SSH_AGENTC_UNLOCK) {
 714                 buffer_clear(&e->request);
 715                 switch (type) {
 716                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 717                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 718                         /* send empty lists */
 719                         no_identities(e, type);
 720                         break;
 721                 default:
 722                         /* send a fail message for all other request types */
 723                         buffer_put_int(&e->output, 1);
 724                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 725                 }
 726                 return;
 727         }
 728
 729         debug("type %d", type);
 730         switch (type) {
 731         case SSH_AGENTC_LOCK:
 732         case SSH_AGENTC_UNLOCK:
 733                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 734                 break;
 735         /* ssh1 */
 736         case SSH_AGENTC_RSA_CHALLENGE:
 737                 process_authentication_challenge1(e);
 738                 break;
 739         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 740                 process_request_identities(e, 1);
 741                 break;
 742         case SSH_AGENTC_ADD_RSA_IDENTITY:
 743         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 744                 process_add_identity(e, 1);
 745                 break;
 746         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 747                 process_remove_identity(e, 1);
 748                 break;
 749         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 750                 process_remove_all_identities(e, 1);
 751                 break;
 752         /* ssh2 */
 753         case SSH2_AGENTC_SIGN_REQUEST:
 754                 process_sign_request2(e);
 755                 break;
 756         case SSH2_AGENTC_REQUEST_IDENTITIES:
 757                 process_request_identities(e, 2);
 758                 break;
 759         case SSH2_AGENTC_ADD_IDENTITY:
 760         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 761                 process_add_identity(e, 2);
 762                 break;
 763         case SSH2_AGENTC_REMOVE_IDENTITY:
 764                 process_remove_identity(e, 2);
 765                 break;
 766         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 767                 process_remove_all_identities(e, 2);
 768                 break;
 769 #ifdef SMARTCARD
 770         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 771         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 772                 process_add_smartcard_key(e);
 773                 break;
 774         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 775                 process_remove_smartcard_key(e);
 776                 break;
 777 #endif /* SMARTCARD */
 778         default:
 779                 /* Unknown message.  Respond with failure. */
 780                 error("Unknown message %d", type);
 781                 buffer_clear(&e->request);
 782                 buffer_put_int(&e->output, 1);
 783                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 784                 break;
 785         }
 786 }
 787
 788 static void
 789 new_socket(sock_type type, int fd)
 790 {
 791         u_int i, old_alloc, new_alloc;
 792
 793         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 794                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 795
 796         if (fd > max_fd)
 797                 max_fd = fd;
 798
 799         for (i = 0; i < sockets_alloc; i++)
 800                 if (sockets[i].type == AUTH_UNUSED) {
 801                         sockets[i].fd = fd;
 802                         buffer_init(&sockets[i].input);
 803                         buffer_init(&sockets[i].output);
 804                         buffer_init(&sockets[i].request);
 805                         sockets[i].type = type;
 806                         return;
 807                 }
 808         old_alloc = sockets_alloc;
 809         new_alloc = sockets_alloc + 10;
 810         if (sockets)
 811                 sockets = xrealloc(sockets, new_alloc * sizeof(sockets[0]));
 812         else
 813                 sockets = xmalloc(new_alloc * sizeof(sockets[0]));
 814         for (i = old_alloc; i < new_alloc; i++)
 815                 sockets[i].type = AUTH_UNUSED;
 816         sockets_alloc = new_alloc;
 817         sockets[old_alloc].fd = fd;
 818         buffer_init(&sockets[old_alloc].input);
 819         buffer_init(&sockets[old_alloc].output);
 820         buffer_init(&sockets[old_alloc].request);
 821         sockets[old_alloc].type = type;
 822 }
 823
 824 static int
 825 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 826 {
 827         u_int i, sz;
 828         int n = 0;
 829
 830         for (i = 0; i < sockets_alloc; i++) {
 831                 switch (sockets[i].type) {
 832                 case AUTH_SOCKET:
 833                 case AUTH_CONNECTION:
 834                         n = MAX(n, sockets[i].fd);
 835                         break;
 836                 case AUTH_UNUSED:
 837                         break;
 838                 default:
 839                         fatal("Unknown socket type %d", sockets[i].type);
 840                         break;
 841                 }
 842         }
 843
 844         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 845         if (*fdrp == NULL || sz > *nallocp) {
 846                 if (*fdrp)
 847                         xfree(*fdrp);
 848                 if (*fdwp)
 849                         xfree(*fdwp);
 850                 *fdrp = xmalloc(sz);
 851                 *fdwp = xmalloc(sz);
 852                 *nallocp = sz;
 853         }
 854         if (n < *fdl)
 855                 debug("XXX shrink: %d < %d", n, *fdl);
 856         *fdl = n;
 857         memset(*fdrp, 0, sz);
 858         memset(*fdwp, 0, sz);
 859
 860         for (i = 0; i < sockets_alloc; i++) {
 861                 switch (sockets[i].type) {
 862                 case AUTH_SOCKET:
 863                 case AUTH_CONNECTION:
 864                         FD_SET(sockets[i].fd, *fdrp);
 865                         if (buffer_len(&sockets[i].output) > 0)
 866                                 FD_SET(sockets[i].fd, *fdwp);
 867                         break;
 868                 default:
 869                         break;
 870                 }
 871         }
 872         return (1);
 873 }
 874
 875 static void
 876 after_select(fd_set *readset, fd_set *writeset)
 877 {
 878         struct sockaddr_un sunaddr;
 879         socklen_t slen;
 880         char buf[1024];
 881         int len, sock;
 882         u_int i;
 883         uid_t euid;
 884         gid_t egid;
 885
 886         for (i = 0; i < sockets_alloc; i++)
 887                 switch (sockets[i].type) {
 888                 case AUTH_UNUSED:
 889                         break;
 890                 case AUTH_SOCKET:
 891                         if (FD_ISSET(sockets[i].fd, readset)) {
 892                                 slen = sizeof(sunaddr);
 893                                 sock = accept(sockets[i].fd,
 894                                     (struct sockaddr *) &sunaddr, &slen);
 895                                 if (sock < 0) {
 896                                         error("accept from AUTH_SOCKET: %s",
 897                                             strerror(errno));
 898                                         break;
 899                                 }
 900                                 if (getpeereid(sock, &euid, &egid) < 0) {
 901                                         error("getpeereid %d failed: %s",
 902                                             sock, strerror(errno));
 903                                         close(sock);
 904                                         break;
 905                                 }
 906                                 if ((euid != 0) && (getuid() != euid)) {
 907                                         error("uid mismatch: "
 908                                             "peer euid %u != uid %u",
 909                                             (u_int) euid, (u_int) getuid());
 910                                         close(sock);
 911                                         break;
 912                                 }
 913                                 new_socket(AUTH_CONNECTION, sock);
 914                         }
 915                         break;
 916                 case AUTH_CONNECTION:
 917                         if (buffer_len(&sockets[i].output) > 0 &&
 918                             FD_ISSET(sockets[i].fd, writeset)) {
 919                                 do {
 920                                         len = write(sockets[i].fd,
 921                                             buffer_ptr(&sockets[i].output),
 922                                             buffer_len(&sockets[i].output));
 923                                         if (len == -1 && (errno == EAGAIN ||
 924                                             errno == EINTR))
 925                                                 continue;
 926                                         break;
 927                                 } while (1);
 928                                 if (len <= 0) {
 929                                         close_socket(&sockets[i]);
 930                                         break;
 931                                 }
 932                                 buffer_consume(&sockets[i].output, len);
 933                         }
 934                         if (FD_ISSET(sockets[i].fd, readset)) {
 935                                 do {
 936                                         len = read(sockets[i].fd, buf, sizeof(buf));
 937                                         if (len == -1 && (errno == EAGAIN ||
 938                                             errno == EINTR))
 939                                                 continue;
 940                                         break;
 941                                 } while (1);
 942                                 if (len <= 0) {
 943                                         close_socket(&sockets[i]);
 944                                         break;
 945                                 }
 946                                 buffer_append(&sockets[i].input, buf, len);
 947                                 process_message(&sockets[i]);
 948                         }
 949                         break;
 950                 default:
 951                         fatal("Unknown type %d", sockets[i].type);
 952                 }
 953 }
 954
 955 static void
 956 cleanup_socket(void)
 957 {
 958         if (socket_name[0])
 959                 unlink(socket_name);
 960         if (socket_dir[0])
 961                 rmdir(socket_dir);
 962 }
 963
 964 void
 965 cleanup_exit(int i)
 966 {
 967         cleanup_socket();
 968         _exit(i);
 969 }
 970
 971 static void
 972 cleanup_handler(int sig)
 973 {
 974         cleanup_socket();
 975         _exit(2);
 976 }
 977
 978 static void
 979 check_parent_exists(int sig)
 980 {
 981         int save_errno = errno;
 982
 983         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 984                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 985                 cleanup_handler(sig); /* safe */
 986         }
 987         mysignal(SIGALRM, check_parent_exists);
 988         alarm(10);
 989         errno = save_errno;
 990 }
 991
 992 static void
 993 usage(void)
 994 {
 995         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 996             __progname);
 997         fprintf(stderr, "Options:\n");
 998         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 999         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1000         fprintf(stderr, "  -k          Kill the current agent.\n");
1001         fprintf(stderr, "  -d          Debug mode.\n");
1002         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1003         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1004         exit(1);
1005 }
1006
1007 int
1008 main(int ac, char **av)
1009 {
1010         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1011         int sock, fd,  ch, nalloc;
1012         char *shell, *format, *pidstr, *agentsocket = NULL;
1013         fd_set *readsetp = NULL, *writesetp = NULL;
1014         struct sockaddr_un sunaddr;
1015 #ifdef HAVE_SETRLIMIT
1016         struct rlimit rlim;
1017 #endif
1018 #ifdef HAVE_CYGWIN
1019         int prev_mask;
1020 #endif
1021         extern int optind;
1022         extern char *optarg;
1023         pid_t pid;
1024         char pidstrbuf[1 + 3 * sizeof pid];
1025
1026         /* drop */
1027         setegid(getgid());
1028         setgid(getgid());
1029
1030 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1031         /* Disable ptrace on Linux without sgid bit */
1032         prctl(PR_SET_DUMPABLE, 0);
1033 #endif
1034
1035         SSLeay_add_all_algorithms();
1036
1037         __progname = ssh_get_progname(av[0]);
1038         init_rng();
1039         seed_rng();
1040
1041         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1042                 switch (ch) {
1043                 case 'c':
1044                         if (s_flag)
1045                                 usage();
1046                         c_flag++;
1047                         break;
1048                 case 'k':
1049                         k_flag++;
1050                         break;
1051                 case 's':
1052                         if (c_flag)
1053                                 usage();
1054                         s_flag++;
1055                         break;
1056                 case 'd':
1057                         if (d_flag)
1058                                 usage();
1059                         d_flag++;
1060                         break;
1061                 case 'a':
1062                         agentsocket = optarg;
1063                         break;
1064                 case 't':
1065                         if ((lifetime = convtime(optarg)) == -1) {
1066                                 fprintf(stderr, "Invalid lifetime\n");
1067                                 usage();
1068                         }
1069                         break;
1070                 default:
1071                         usage();
1072                 }
1073         }
1074         ac -= optind;
1075         av += optind;
1076
1077         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1078                 usage();
1079
1080         if (ac == 0 && !c_flag && !s_flag) {
1081                 shell = getenv("SHELL");
1082                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1083                         c_flag = 1;
1084         }
1085         if (k_flag) {
1086                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1087                 if (pidstr == NULL) {
1088                         fprintf(stderr, "%s not set, cannot kill agent\n",
1089                             SSH_AGENTPID_ENV_NAME);
1090                         exit(1);
1091                 }
1092                 pid = atoi(pidstr);
1093                 if (pid < 1) {
1094                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
1095                             SSH_AGENTPID_ENV_NAME, pidstr);
1096                         exit(1);
1097                 }
1098                 if (kill(pid, SIGTERM) == -1) {
1099                         perror("kill");
1100                         exit(1);
1101                 }
1102                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1103                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1104                 printf(format, SSH_AGENTPID_ENV_NAME);
1105                 printf("echo Agent pid %ld killed;\n", (long)pid);
1106                 exit(0);
1107         }
1108         parent_pid = getpid();
1109
1110         if (agentsocket == NULL) {
1111                 /* Create private directory for agent socket */
1112                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1113                 if (mkdtemp(socket_dir) == NULL) {
1114                         perror("mkdtemp: private socket dir");
1115                         exit(1);
1116                 }
1117                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1118                     (long)parent_pid);
1119         } else {
1120                 /* Try to use specified agent socket */
1121                 socket_dir[0] = '\0';
1122                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1123         }
1124
1125         /*
1126          * Create socket early so it will exist before command gets run from
1127          * the parent.
1128          */
1129         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1130         if (sock < 0) {
1131                 perror("socket");
1132                 cleanup_exit(1);
1133         }
1134         memset(&sunaddr, 0, sizeof(sunaddr));
1135         sunaddr.sun_family = AF_UNIX;
1136         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1137 #ifdef HAVE_CYGWIN
1138         prev_mask = umask(0177);
1139 #endif
1140         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1141                 perror("bind");
1142 #ifdef HAVE_CYGWIN
1143                 umask(prev_mask);
1144 #endif
1145                 cleanup_exit(1);
1146         }
1147 #ifdef HAVE_CYGWIN
1148         umask(prev_mask);
1149 #endif
1150         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1151                 perror("listen");
1152                 cleanup_exit(1);
1153         }
1154
1155         /*
1156          * Fork, and have the parent execute the command, if any, or present
1157          * the socket data.  The child continues as the authentication agent.
1158          */
1159         if (d_flag) {
1160                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1161                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1162                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1163                     SSH_AUTHSOCKET_ENV_NAME);
1164                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1165                 goto skip;
1166         }
1167         pid = fork();
1168         if (pid == -1) {
1169                 perror("fork");
1170                 cleanup_exit(1);
1171         }
1172         if (pid != 0) {         /* Parent - execute the given command. */
1173                 close(sock);
1174                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1175                 if (ac == 0) {
1176                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1177                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1178                             SSH_AUTHSOCKET_ENV_NAME);
1179                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1180                             SSH_AGENTPID_ENV_NAME);
1181                         printf("echo Agent pid %ld;\n", (long)pid);
1182                         exit(0);
1183                 }
1184                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1185                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1186                         perror("setenv");
1187                         exit(1);
1188                 }
1189                 execvp(av[0], av);
1190                 perror(av[0]);
1191                 exit(1);
1192         }
1193         /* child */
1194         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1195
1196         if (setsid() == -1) {
1197                 error("setsid: %s", strerror(errno));
1198                 cleanup_exit(1);
1199         }
1200
1201         (void)chdir("/");
1202         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1203                 /* XXX might close listen socket */
1204                 (void)dup2(fd, STDIN_FILENO);
1205                 (void)dup2(fd, STDOUT_FILENO);
1206                 (void)dup2(fd, STDERR_FILENO);
1207                 if (fd > 2)
1208                         close(fd);
1209         }
1210
1211 #ifdef HAVE_SETRLIMIT
1212         /* deny core dumps, since memory contains unencrypted private keys */
1213         rlim.rlim_cur = rlim.rlim_max = 0;
1214         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1215                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1216                 cleanup_exit(1);
1217         }
1218 #endif
1219
1220 skip:
1221         new_socket(AUTH_SOCKET, sock);
1222         if (ac > 0) {
1223                 mysignal(SIGALRM, check_parent_exists);
1224                 alarm(10);
1225         }
1226         idtab_init();
1227         if (!d_flag)
1228                 signal(SIGINT, SIG_IGN);
1229         signal(SIGPIPE, SIG_IGN);
1230         signal(SIGHUP, cleanup_handler);
1231         signal(SIGTERM, cleanup_handler);
1232         nalloc = 0;
1233
1234         while (1) {
1235                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1236                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1237                         if (errno == EINTR)
1238                                 continue;
1239                         fatal("select: %s", strerror(errno));
1240                 }
1241                 after_select(readsetp, writesetp);
1242         }
1243         /* NOTREACHED */
1244 }