crypto/openssh/ssh-agent.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * The authentication agent program.
   6  *
   7  * As far as I am concerned, the code I have written for this software
   8  * can be used freely for any purpose.  Any derived versions of this
   9  * software must be clearly marked as such, and if the derived work is
  10  * incompatible with the protocol description in the RFC file, it must be
  11  * called by a name other than "ssh" or "Secure Shell".
  12  *
  13  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  14  *
  15  * Redistribution and use in source and binary forms, with or without
  16  * modification, are permitted provided that the following conditions
  17  * are met:
  18  * 1. Redistributions of source code must retain the above copyright
  19  *    notice, this list of conditions and the following disclaimer.
  20  * 2. Redistributions in binary form must reproduce the above copyright
  21  *    notice, this list of conditions and the following disclaimer in the
  22  *    documentation and/or other materials provided with the distribution.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  27  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  28  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  29  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  30  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  31  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  32  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  33  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 #include "includes.h"
  37 #include "openbsd-compat/sys-queue.h"
  38 RCSID("$OpenBSD: ssh-agent.c,v 1.105 2002/10/01 20:34:12 markus Exp $");
  39 RCSID("$FreeBSD: src/crypto/openssh/ssh-agent.c,v 1.2.2.10 2003/02/11 08:27:40 des Exp $");
  40
  41 #include <openssl/evp.h>
  42 #include <openssl/md5.h>
  43
  44 #include "ssh.h"
  45 #include "rsa.h"
  46 #include "buffer.h"
  47 #include "bufaux.h"
  48 #include "xmalloc.h"
  49 #include "getput.h"
  50 #include "key.h"
  51 #include "authfd.h"
  52 #include "compat.h"
  53 #include "log.h"
  54
  55 #ifdef SMARTCARD
  56 #include "scard.h"
  57 #endif
  58
  59 typedef enum {
  60         AUTH_UNUSED,
  61         AUTH_SOCKET,
  62         AUTH_CONNECTION
  63 } sock_type;
  64
  65 typedef struct {
  66         int fd;
  67         sock_type type;
  68         Buffer input;
  69         Buffer output;
  70         Buffer request;
  71 } SocketEntry;
  72
  73 u_int sockets_alloc = 0;
  74 SocketEntry *sockets = NULL;
  75
  76 typedef struct identity {
  77         TAILQ_ENTRY(identity) next;
  78         Key *key;
  79         char *comment;
  80         u_int death;
  81 } Identity;
  82
  83 typedef struct {
  84         int nentries;
  85         TAILQ_HEAD(idqueue, identity) idlist;
  86 } Idtab;
  87
  88 /* private key table, one per protocol version */
  89 Idtab idtable[3];
  90
  91 int max_fd = 0;
  92
  93 /* pid of shell == parent of agent */
  94 pid_t parent_pid = -1;
  95
  96 /* pathname and directory for AUTH_SOCKET */
  97 char socket_name[1024];
  98 char socket_dir[1024];
  99
 100 /* locking */
 101 int locked = 0;
 102 char *lock_passwd = NULL;
 103
 104 #ifdef HAVE___PROGNAME
 105 extern char *__progname;
 106 #else
 107 char *__progname;
 108 #endif
 109
 110 static void
 111 close_socket(SocketEntry *e)
 112 {
 113         close(e->fd);
 114         e->fd = -1;
 115         e->type = AUTH_UNUSED;
 116         buffer_free(&e->input);
 117         buffer_free(&e->output);
 118         buffer_free(&e->request);
 119 }
 120
 121 static void
 122 idtab_init(void)
 123 {
 124         int i;
 125
 126         for (i = 0; i <=2; i++) {
 127                 TAILQ_INIT(&idtable[i].idlist);
 128                 idtable[i].nentries = 0;
 129         }
 130 }
 131
 132 /* return private key table for requested protocol version */
 133 static Idtab *
 134 idtab_lookup(int version)
 135 {
 136         if (version < 1 || version > 2)
 137                 fatal("internal error, bad protocol version %d", version);
 138         return &idtable[version];
 139 }
 140
 141 static void
 142 free_identity(Identity *id)
 143 {
 144         key_free(id->key);
 145         xfree(id->comment);
 146         xfree(id);
 147 }
 148
 149 /* return matching private key for given public key */
 150 static Identity *
 151 lookup_identity(Key *key, int version)
 152 {
 153         Identity *id;
 154
 155         Idtab *tab = idtab_lookup(version);
 156         TAILQ_FOREACH(id, &tab->idlist, next) {
 157                 if (key_equal(key, id->key))
 158                         return (id);
 159         }
 160         return (NULL);
 161 }
 162
 163 /* send list of supported public keys to 'client' */
 164 static void
 165 process_request_identities(SocketEntry *e, int version)
 166 {
 167         Idtab *tab = idtab_lookup(version);
 168         Identity *id;
 169         Buffer msg;
 170
 171         buffer_init(&msg);
 172         buffer_put_char(&msg, (version == 1) ?
 173             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 174         buffer_put_int(&msg, tab->nentries);
 175         TAILQ_FOREACH(id, &tab->idlist, next) {
 176                 if (id->key->type == KEY_RSA1) {
 177                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 178                         buffer_put_bignum(&msg, id->key->rsa->e);
 179                         buffer_put_bignum(&msg, id->key->rsa->n);
 180                 } else {
 181                         u_char *blob;
 182                         u_int blen;
 183                         key_to_blob(id->key, &blob, &blen);
 184                         buffer_put_string(&msg, blob, blen);
 185                         xfree(blob);
 186                 }
 187                 buffer_put_cstring(&msg, id->comment);
 188         }
 189         buffer_put_int(&e->output, buffer_len(&msg));
 190         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 191         buffer_free(&msg);
 192 }
 193
 194 /* ssh1 only */
 195 static void
 196 process_authentication_challenge1(SocketEntry *e)
 197 {
 198         u_char buf[32], mdbuf[16], session_id[16];
 199         u_int response_type;
 200         BIGNUM *challenge;
 201         Identity *id;
 202         int i, len;
 203         Buffer msg;
 204         MD5_CTX md;
 205         Key *key;
 206
 207         buffer_init(&msg);
 208         key = key_new(KEY_RSA1);
 209         if ((challenge = BN_new()) == NULL)
 210                 fatal("process_authentication_challenge1: BN_new failed");
 211
 212         (void) buffer_get_int(&e->request);                     /* ignored */
 213         buffer_get_bignum(&e->request, key->rsa->e);
 214         buffer_get_bignum(&e->request, key->rsa->n);
 215         buffer_get_bignum(&e->request, challenge);
 216
 217         /* Only protocol 1.1 is supported */
 218         if (buffer_len(&e->request) == 0)
 219                 goto failure;
 220         buffer_get(&e->request, session_id, 16);
 221         response_type = buffer_get_int(&e->request);
 222         if (response_type != 1)
 223                 goto failure;
 224
 225         id = lookup_identity(key, 1);
 226         if (id != NULL) {
 227                 Key *private = id->key;
 228                 /* Decrypt the challenge using the private key. */
 229                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 230                         goto failure;
 231
 232                 /* The response is MD5 of decrypted challenge plus session id. */
 233                 len = BN_num_bytes(challenge);
 234                 if (len <= 0 || len > 32) {
 235                         log("process_authentication_challenge: bad challenge length %d", len);
 236                         goto failure;
 237                 }
 238                 memset(buf, 0, 32);
 239                 BN_bn2bin(challenge, buf + 32 - len);
 240                 MD5_Init(&md);
 241                 MD5_Update(&md, buf, 32);
 242                 MD5_Update(&md, session_id, 16);
 243                 MD5_Final(mdbuf, &md);
 244
 245                 /* Send the response. */
 246                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 247                 for (i = 0; i < 16; i++)
 248                         buffer_put_char(&msg, mdbuf[i]);
 249                 goto send;
 250         }
 251
 252 failure:
 253         /* Unknown identity or protocol error.  Send failure. */
 254         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 255 send:
 256         buffer_put_int(&e->output, buffer_len(&msg));
 257         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 258         key_free(key);
 259         BN_clear_free(challenge);
 260         buffer_free(&msg);
 261 }
 262
 263 /* ssh2 only */
 264 static void
 265 process_sign_request2(SocketEntry *e)
 266 {
 267         u_char *blob, *data, *signature = NULL;
 268         u_int blen, dlen, slen = 0;
 269         extern int datafellows;
 270         int ok = -1, flags;
 271         Buffer msg;
 272         Key *key;
 273
 274         datafellows = 0;
 275
 276         blob = buffer_get_string(&e->request, &blen);
 277         data = buffer_get_string(&e->request, &dlen);
 278
 279         flags = buffer_get_int(&e->request);
 280         if (flags & SSH_AGENT_OLD_SIGNATURE)
 281                 datafellows = SSH_BUG_SIGBLOB;
 282
 283         key = key_from_blob(blob, blen);
 284         if (key != NULL) {
 285                 Identity *id = lookup_identity(key, 2);
 286                 if (id != NULL)
 287                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 288         }
 289         key_free(key);
 290         buffer_init(&msg);
 291         if (ok == 0) {
 292                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 293                 buffer_put_string(&msg, signature, slen);
 294         } else {
 295                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 296         }
 297         buffer_put_int(&e->output, buffer_len(&msg));
 298         buffer_append(&e->output, buffer_ptr(&msg),
 299             buffer_len(&msg));
 300         buffer_free(&msg);
 301         xfree(data);
 302         xfree(blob);
 303         if (signature != NULL)
 304                 xfree(signature);
 305 }
 306
 307 /* shared */
 308 static void
 309 process_remove_identity(SocketEntry *e, int version)
 310 {
 311         u_int blen, bits;
 312         int success = 0;
 313         Key *key = NULL;
 314         u_char *blob;
 315
 316         switch (version) {
 317         case 1:
 318                 key = key_new(KEY_RSA1);
 319                 bits = buffer_get_int(&e->request);
 320                 buffer_get_bignum(&e->request, key->rsa->e);
 321                 buffer_get_bignum(&e->request, key->rsa->n);
 322
 323                 if (bits != key_size(key))
 324                         log("Warning: identity keysize mismatch: actual %u, announced %u",
 325                             key_size(key), bits);
 326                 break;
 327         case 2:
 328                 blob = buffer_get_string(&e->request, &blen);
 329                 key = key_from_blob(blob, blen);
 330                 xfree(blob);
 331                 break;
 332         }
 333         if (key != NULL) {
 334                 Identity *id = lookup_identity(key, version);
 335                 if (id != NULL) {
 336                         /*
 337                          * We have this key.  Free the old key.  Since we
 338                          * don\'t want to leave empty slots in the middle of
 339                          * the array, we actually free the key there and move
 340                          * all the entries between the empty slot and the end
 341                          * of the array.
 342                          */
 343                         Idtab *tab = idtab_lookup(version);
 344                         if (tab->nentries < 1)
 345                                 fatal("process_remove_identity: "
 346                                     "internal error: tab->nentries %d",
 347                                     tab->nentries);
 348                         TAILQ_REMOVE(&tab->idlist, id, next);
 349                         free_identity(id);
 350                         tab->nentries--;
 351                         success = 1;
 352                 }
 353                 key_free(key);
 354         }
 355         buffer_put_int(&e->output, 1);
 356         buffer_put_char(&e->output,
 357             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 358 }
 359
 360 static void
 361 process_remove_all_identities(SocketEntry *e, int version)
 362 {
 363         Idtab *tab = idtab_lookup(version);
 364         Identity *id;
 365
 366         /* Loop over all identities and clear the keys. */
 367         for (id = TAILQ_FIRST(&tab->idlist); id;
 368             id = TAILQ_FIRST(&tab->idlist)) {
 369                 TAILQ_REMOVE(&tab->idlist, id, next);
 370                 free_identity(id);
 371         }
 372
 373         /* Mark that there are no identities. */
 374         tab->nentries = 0;
 375
 376         /* Send success. */
 377         buffer_put_int(&e->output, 1);
 378         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 379 }
 380
 381 static void
 382 reaper(void)
 383 {
 384         u_int now = time(NULL);
 385         Identity *id, *nxt;
 386         int version;
 387         Idtab *tab;
 388
 389         for (version = 1; version < 3; version++) {
 390                 tab = idtab_lookup(version);
 391                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 392                         nxt = TAILQ_NEXT(id, next);
 393                         if (id->death != 0 && now >= id->death) {
 394                                 TAILQ_REMOVE(&tab->idlist, id, next);
 395                                 free_identity(id);
 396                                 tab->nentries--;
 397                         }
 398                 }
 399         }
 400 }
 401
 402 static void
 403 process_add_identity(SocketEntry *e, int version)
 404 {
 405         Idtab *tab = idtab_lookup(version);
 406         int type, success = 0, death = 0;
 407         char *type_name, *comment;
 408         Key *k = NULL;
 409
 410         switch (version) {
 411         case 1:
 412                 k = key_new_private(KEY_RSA1);
 413                 (void) buffer_get_int(&e->request);             /* ignored */
 414                 buffer_get_bignum(&e->request, k->rsa->n);
 415                 buffer_get_bignum(&e->request, k->rsa->e);
 416                 buffer_get_bignum(&e->request, k->rsa->d);
 417                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 418
 419                 /* SSH and SSL have p and q swapped */
 420                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 421                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 422
 423                 /* Generate additional parameters */
 424                 rsa_generate_additional_parameters(k->rsa);
 425                 break;
 426         case 2:
 427                 type_name = buffer_get_string(&e->request, NULL);
 428                 type = key_type_from_name(type_name);
 429                 xfree(type_name);
 430                 switch (type) {
 431                 case KEY_DSA:
 432                         k = key_new_private(type);
 433                         buffer_get_bignum2(&e->request, k->dsa->p);
 434                         buffer_get_bignum2(&e->request, k->dsa->q);
 435                         buffer_get_bignum2(&e->request, k->dsa->g);
 436                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 437                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 438                         break;
 439                 case KEY_RSA:
 440                         k = key_new_private(type);
 441                         buffer_get_bignum2(&e->request, k->rsa->n);
 442                         buffer_get_bignum2(&e->request, k->rsa->e);
 443                         buffer_get_bignum2(&e->request, k->rsa->d);
 444                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 445                         buffer_get_bignum2(&e->request, k->rsa->p);
 446                         buffer_get_bignum2(&e->request, k->rsa->q);
 447
 448                         /* Generate additional parameters */
 449                         rsa_generate_additional_parameters(k->rsa);
 450                         break;
 451                 default:
 452                         buffer_clear(&e->request);
 453                         goto send;
 454                 }
 455                 break;
 456         }
 457         comment = buffer_get_string(&e->request, NULL);
 458         if (k == NULL) {
 459                 xfree(comment);
 460                 goto send;
 461         }
 462         success = 1;
 463         while (buffer_len(&e->request)) {
 464                 switch (buffer_get_char(&e->request)) {
 465                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 466                         death = time(NULL) + buffer_get_int(&e->request);
 467                         break;
 468                 default:
 469                         break;
 470                 }
 471         }
 472         if (lookup_identity(k, version) == NULL) {
 473                 Identity *id = xmalloc(sizeof(Identity));
 474                 id->key = k;
 475                 id->comment = comment;
 476                 id->death = death;
 477                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 478                 /* Increment the number of identities. */
 479                 tab->nentries++;
 480         } else {
 481                 key_free(k);
 482                 xfree(comment);
 483         }
 484 send:
 485         buffer_put_int(&e->output, 1);
 486         buffer_put_char(&e->output,
 487             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 488 }
 489
 490 /* XXX todo: encrypt sensitive data with passphrase */
 491 static void
 492 process_lock_agent(SocketEntry *e, int lock)
 493 {
 494         int success = 0;
 495         char *passwd;
 496
 497         passwd = buffer_get_string(&e->request, NULL);
 498         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 499                 locked = 0;
 500                 memset(lock_passwd, 0, strlen(lock_passwd));
 501                 xfree(lock_passwd);
 502                 lock_passwd = NULL;
 503                 success = 1;
 504         } else if (!locked && lock) {
 505                 locked = 1;
 506                 lock_passwd = xstrdup(passwd);
 507                 success = 1;
 508         }
 509         memset(passwd, 0, strlen(passwd));
 510         xfree(passwd);
 511
 512         buffer_put_int(&e->output, 1);
 513         buffer_put_char(&e->output,
 514             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 515 }
 516
 517 static void
 518 no_identities(SocketEntry *e, u_int type)
 519 {
 520         Buffer msg;
 521
 522         buffer_init(&msg);
 523         buffer_put_char(&msg,
 524             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 525             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 526         buffer_put_int(&msg, 0);
 527         buffer_put_int(&e->output, buffer_len(&msg));
 528         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 529         buffer_free(&msg);
 530 }
 531
 532 #ifdef SMARTCARD
 533 static void
 534 process_add_smartcard_key (SocketEntry *e)
 535 {
 536         char *sc_reader_id = NULL, *pin;
 537         int i, version, success = 0;
 538         Key **keys, *k;
 539         Identity *id;
 540         Idtab *tab;
 541
 542         sc_reader_id = buffer_get_string(&e->request, NULL);
 543         pin = buffer_get_string(&e->request, NULL);
 544         keys = sc_get_keys(sc_reader_id, pin);
 545         xfree(sc_reader_id);
 546         xfree(pin);
 547
 548         if (keys == NULL || keys[0] == NULL) {
 549                 error("sc_get_keys failed");
 550                 goto send;
 551         }
 552         for (i = 0; keys[i] != NULL; i++) {
 553                 k = keys[i];
 554                 version = k->type == KEY_RSA1 ? 1 : 2;
 555                 tab = idtab_lookup(version);
 556                 if (lookup_identity(k, version) == NULL) {
 557                         id = xmalloc(sizeof(Identity));
 558                         id->key = k;
 559                         id->comment = xstrdup("smartcard key");
 560                         id->death = 0;
 561                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 562                         tab->nentries++;
 563                         success = 1;
 564                 } else {
 565                         key_free(k);
 566                 }
 567                 keys[i] = NULL;
 568         }
 569         xfree(keys);
 570 send:
 571         buffer_put_int(&e->output, 1);
 572         buffer_put_char(&e->output,
 573             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 574 }
 575
 576 static void
 577 process_remove_smartcard_key(SocketEntry *e)
 578 {
 579         char *sc_reader_id = NULL, *pin;
 580         int i, version, success = 0;
 581         Key **keys, *k = NULL;
 582         Identity *id;
 583         Idtab *tab;
 584
 585         sc_reader_id = buffer_get_string(&e->request, NULL);
 586         pin = buffer_get_string(&e->request, NULL);
 587         keys = sc_get_keys(sc_reader_id, pin);
 588         xfree(sc_reader_id);
 589         xfree(pin);
 590
 591         if (keys == NULL || keys[0] == NULL) {
 592                 error("sc_get_keys failed");
 593                 goto send;
 594         }
 595         for (i = 0; keys[i] != NULL; i++) {
 596                 k = keys[i];
 597                 version = k->type == KEY_RSA1 ? 1 : 2;
 598                 if ((id = lookup_identity(k, version)) != NULL) {
 599                         tab = idtab_lookup(version);
 600                         TAILQ_REMOVE(&tab->idlist, id, next);
 601                         tab->nentries--;
 602                         free_identity(id);
 603                         success = 1;
 604                 }
 605                 key_free(k);
 606                 keys[i] = NULL;
 607         }
 608         xfree(keys);
 609 send:
 610         buffer_put_int(&e->output, 1);
 611         buffer_put_char(&e->output,
 612             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 613 }
 614 #endif /* SMARTCARD */
 615
 616 /* dispatch incoming messages */
 617
 618 static void
 619 process_message(SocketEntry *e)
 620 {
 621         u_int msg_len, type;
 622         u_char *cp;
 623
 624         /* kill dead keys */
 625         reaper();
 626
 627         if (buffer_len(&e->input) < 5)
 628                 return;         /* Incomplete message. */
 629         cp = buffer_ptr(&e->input);
 630         msg_len = GET_32BIT(cp);
 631         if (msg_len > 256 * 1024) {
 632                 close_socket(e);
 633                 return;
 634         }
 635         if (buffer_len(&e->input) < msg_len + 4)
 636                 return;
 637
 638         /* move the current input to e->request */
 639         buffer_consume(&e->input, 4);
 640         buffer_clear(&e->request);
 641         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 642         buffer_consume(&e->input, msg_len);
 643         type = buffer_get_char(&e->request);
 644
 645         /* check wheter agent is locked */
 646         if (locked && type != SSH_AGENTC_UNLOCK) {
 647                 buffer_clear(&e->request);
 648                 switch (type) {
 649                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 650                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 651                         /* send empty lists */
 652                         no_identities(e, type);
 653                         break;
 654                 default:
 655                         /* send a fail message for all other request types */
 656                         buffer_put_int(&e->output, 1);
 657                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 658                 }
 659                 return;
 660         }
 661
 662         debug("type %d", type);
 663         switch (type) {
 664         case SSH_AGENTC_LOCK:
 665         case SSH_AGENTC_UNLOCK:
 666                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 667                 break;
 668         /* ssh1 */
 669         case SSH_AGENTC_RSA_CHALLENGE:
 670                 process_authentication_challenge1(e);
 671                 break;
 672         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 673                 process_request_identities(e, 1);
 674                 break;
 675         case SSH_AGENTC_ADD_RSA_IDENTITY:
 676         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 677                 process_add_identity(e, 1);
 678                 break;
 679         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 680                 process_remove_identity(e, 1);
 681                 break;
 682         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 683                 process_remove_all_identities(e, 1);
 684                 break;
 685         /* ssh2 */
 686         case SSH2_AGENTC_SIGN_REQUEST:
 687                 process_sign_request2(e);
 688                 break;
 689         case SSH2_AGENTC_REQUEST_IDENTITIES:
 690                 process_request_identities(e, 2);
 691                 break;
 692         case SSH2_AGENTC_ADD_IDENTITY:
 693         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 694                 process_add_identity(e, 2);
 695                 break;
 696         case SSH2_AGENTC_REMOVE_IDENTITY:
 697                 process_remove_identity(e, 2);
 698                 break;
 699         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 700                 process_remove_all_identities(e, 2);
 701                 break;
 702 #ifdef SMARTCARD
 703         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 704                 process_add_smartcard_key(e);
 705                 break;
 706         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 707                 process_remove_smartcard_key(e);
 708                 break;
 709 #endif /* SMARTCARD */
 710         default:
 711                 /* Unknown message.  Respond with failure. */
 712                 error("Unknown message %d", type);
 713                 buffer_clear(&e->request);
 714                 buffer_put_int(&e->output, 1);
 715                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 716                 break;
 717         }
 718 }
 719
 720 static void
 721 new_socket(sock_type type, int fd)
 722 {
 723         u_int i, old_alloc;
 724
 725         if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
 726                 error("fcntl O_NONBLOCK: %s", strerror(errno));
 727
 728         if (fd > max_fd)
 729                 max_fd = fd;
 730
 731         for (i = 0; i < sockets_alloc; i++)
 732                 if (sockets[i].type == AUTH_UNUSED) {
 733                         sockets[i].fd = fd;
 734                         sockets[i].type = type;
 735                         buffer_init(&sockets[i].input);
 736                         buffer_init(&sockets[i].output);
 737                         buffer_init(&sockets[i].request);
 738                         return;
 739                 }
 740         old_alloc = sockets_alloc;
 741         sockets_alloc += 10;
 742         if (sockets)
 743                 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
 744         else
 745                 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
 746         for (i = old_alloc; i < sockets_alloc; i++)
 747                 sockets[i].type = AUTH_UNUSED;
 748         sockets[old_alloc].type = type;
 749         sockets[old_alloc].fd = fd;
 750         buffer_init(&sockets[old_alloc].input);
 751         buffer_init(&sockets[old_alloc].output);
 752         buffer_init(&sockets[old_alloc].request);
 753 }
 754
 755 static int
 756 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp)
 757 {
 758         u_int i, sz;
 759         int n = 0;
 760
 761         for (i = 0; i < sockets_alloc; i++) {
 762                 switch (sockets[i].type) {
 763                 case AUTH_SOCKET:
 764                 case AUTH_CONNECTION:
 765                         n = MAX(n, sockets[i].fd);
 766                         break;
 767                 case AUTH_UNUSED:
 768                         break;
 769                 default:
 770                         fatal("Unknown socket type %d", sockets[i].type);
 771                         break;
 772                 }
 773         }
 774
 775         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 776         if (*fdrp == NULL || sz > *nallocp) {
 777                 if (*fdrp)
 778                         xfree(*fdrp);
 779                 if (*fdwp)
 780                         xfree(*fdwp);
 781                 *fdrp = xmalloc(sz);
 782                 *fdwp = xmalloc(sz);
 783                 *nallocp = sz;
 784         }
 785         if (n < *fdl)
 786                 debug("XXX shrink: %d < %d", n, *fdl);
 787         *fdl = n;
 788         memset(*fdrp, 0, sz);
 789         memset(*fdwp, 0, sz);
 790
 791         for (i = 0; i < sockets_alloc; i++) {
 792                 switch (sockets[i].type) {
 793                 case AUTH_SOCKET:
 794                 case AUTH_CONNECTION:
 795                         FD_SET(sockets[i].fd, *fdrp);
 796                         if (buffer_len(&sockets[i].output) > 0)
 797                                 FD_SET(sockets[i].fd, *fdwp);
 798                         break;
 799                 default:
 800                         break;
 801                 }
 802         }
 803         return (1);
 804 }
 805
 806 static void
 807 after_select(fd_set *readset, fd_set *writeset)
 808 {
 809         struct sockaddr_un sunaddr;
 810         socklen_t slen;
 811         char buf[1024];
 812         int len, sock;
 813         u_int i;
 814         uid_t euid;
 815         gid_t egid;
 816
 817         for (i = 0; i < sockets_alloc; i++)
 818                 switch (sockets[i].type) {
 819                 case AUTH_UNUSED:
 820                         break;
 821                 case AUTH_SOCKET:
 822                         if (FD_ISSET(sockets[i].fd, readset)) {
 823                                 slen = sizeof(sunaddr);
 824                                 sock = accept(sockets[i].fd,
 825                                     (struct sockaddr *) &sunaddr, &slen);
 826                                 if (sock < 0) {
 827                                         error("accept from AUTH_SOCKET: %s",
 828                                             strerror(errno));
 829                                         break;
 830                                 }
 831                                 if (getpeereid(sock, &euid, &egid) < 0) {
 832                                         error("getpeereid %d failed: %s",
 833                                             sock, strerror(errno));
 834                                         close(sock);
 835                                         break;
 836                                 }
 837                                 if ((euid != 0) && (getuid() != euid)) {
 838                                         error("uid mismatch: "
 839                                             "peer euid %u != uid %u",
 840                                             (u_int) euid, (u_int) getuid());
 841                                         close(sock);
 842                                         break;
 843                                 }
 844                                 new_socket(AUTH_CONNECTION, sock);
 845                         }
 846                         break;
 847                 case AUTH_CONNECTION:
 848                         if (buffer_len(&sockets[i].output) > 0 &&
 849                             FD_ISSET(sockets[i].fd, writeset)) {
 850                                 do {
 851                                         len = write(sockets[i].fd,
 852                                             buffer_ptr(&sockets[i].output),
 853                                             buffer_len(&sockets[i].output));
 854                                         if (len == -1 && (errno == EAGAIN ||
 855                                             errno == EINTR))
 856                                                 continue;
 857                                         break;
 858                                 } while (1);
 859                                 if (len <= 0) {
 860                                         close_socket(&sockets[i]);
 861                                         break;
 862                                 }
 863                                 buffer_consume(&sockets[i].output, len);
 864                         }
 865                         if (FD_ISSET(sockets[i].fd, readset)) {
 866                                 do {
 867                                         len = read(sockets[i].fd, buf, sizeof(buf));
 868                                         if (len == -1 && (errno == EAGAIN ||
 869                                             errno == EINTR))
 870                                                 continue;
 871                                         break;
 872                                 } while (1);
 873                                 if (len <= 0) {
 874                                         close_socket(&sockets[i]);
 875                                         break;
 876                                 }
 877                                 buffer_append(&sockets[i].input, buf, len);
 878                                 process_message(&sockets[i]);
 879                         }
 880                         break;
 881                 default:
 882                         fatal("Unknown type %d", sockets[i].type);
 883                 }
 884 }
 885
 886 static void
 887 cleanup_socket(void *p)
 888 {
 889         if (socket_name[0])
 890                 unlink(socket_name);
 891         if (socket_dir[0])
 892                 rmdir(socket_dir);
 893 }
 894
 895 static void
 896 cleanup_exit(int i)
 897 {
 898         cleanup_socket(NULL);
 899         exit(i);
 900 }
 901
 902 static void
 903 cleanup_handler(int sig)
 904 {
 905         cleanup_socket(NULL);
 906         _exit(2);
 907 }
 908
 909 static void
 910 check_parent_exists(int sig)
 911 {
 912         int save_errno = errno;
 913
 914         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 915                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 916                 cleanup_handler(sig); /* safe */
 917         }
 918         signal(SIGALRM, check_parent_exists);
 919         alarm(10);
 920         errno = save_errno;
 921 }
 922
 923 static void
 924 usage(void)
 925 {
 926         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
 927             __progname);
 928         fprintf(stderr, "Options:\n");
 929         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
 930         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
 931         fprintf(stderr, "  -k          Kill the current agent.\n");
 932         fprintf(stderr, "  -d          Debug mode.\n");
 933         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
 934         exit(1);
 935 }
 936
 937 int
 938 main(int ac, char **av)
 939 {
 940         int sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc;
 941         char *shell, *format, *pidstr, *agentsocket = NULL;
 942         fd_set *readsetp = NULL, *writesetp = NULL;
 943         struct sockaddr_un sunaddr;
 944 #ifdef HAVE_SETRLIMIT
 945         struct rlimit rlim;
 946 #endif
 947 #ifdef HAVE_CYGWIN
 948         int prev_mask;
 949 #endif
 950         extern int optind;
 951         extern char *optarg;
 952         pid_t pid;
 953         char pidstrbuf[1 + 3 * sizeof pid];
 954
 955         /* drop */
 956         setegid(getgid());
 957         setgid(getgid());
 958         setuid(geteuid());
 959
 960         SSLeay_add_all_algorithms();
 961
 962         __progname = get_progname(av[0]);
 963         init_rng();
 964         seed_rng();
 965
 966         while ((ch = getopt(ac, av, "cdksa:")) != -1) {
 967                 switch (ch) {
 968                 case 'c':
 969                         if (s_flag)
 970                                 usage();
 971                         c_flag++;
 972                         break;
 973                 case 'k':
 974                         k_flag++;
 975                         break;
 976                 case 's':
 977                         if (c_flag)
 978                                 usage();
 979                         s_flag++;
 980                         break;
 981                 case 'd':
 982                         if (d_flag)
 983                                 usage();
 984                         d_flag++;
 985                         break;
 986                 case 'a':
 987                         agentsocket = optarg;
 988                         break;
 989                 default:
 990                         usage();
 991                 }
 992         }
 993         ac -= optind;
 994         av += optind;
 995
 996         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
 997                 usage();
 998
 999         if (ac == 0 && !c_flag && !s_flag) {
1000                 shell = getenv("SHELL");
1001                 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1002                         c_flag = 1;
1003         }
1004         if (k_flag) {
1005                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1006                 if (pidstr == NULL) {
1007                         fprintf(stderr, "%s not set, cannot kill agent\n",
1008                             SSH_AGENTPID_ENV_NAME);
1009                         exit(1);
1010                 }
1011                 pid = atoi(pidstr);
1012                 if (pid < 1) {
1013                         fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
1014                             SSH_AGENTPID_ENV_NAME, pidstr);
1015                         exit(1);
1016                 }
1017                 if (kill(pid, SIGTERM) == -1) {
1018                         perror("kill");
1019                         exit(1);
1020                 }
1021                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1022                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1023                 printf(format, SSH_AGENTPID_ENV_NAME);
1024                 printf("echo Agent pid %ld killed;\n", (long)pid);
1025                 exit(0);
1026         }
1027         parent_pid = getpid();
1028
1029         if (agentsocket == NULL) {
1030                 /* Create private directory for agent socket */
1031                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
1032                 if (mkdtemp(socket_dir) == NULL) {
1033                         perror("mkdtemp: private socket dir");
1034                         exit(1);
1035                 }
1036                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1037                     (long)parent_pid);
1038         } else {
1039                 /* Try to use specified agent socket */
1040                 socket_dir[0] = '\0';
1041                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1042         }
1043
1044         /*
1045          * Create socket early so it will exist before command gets run from
1046          * the parent.
1047          */
1048         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1049         if (sock < 0) {
1050                 perror("socket");
1051                 cleanup_exit(1);
1052         }
1053         memset(&sunaddr, 0, sizeof(sunaddr));
1054         sunaddr.sun_family = AF_UNIX;
1055         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1056 #ifdef HAVE_CYGWIN
1057         prev_mask = umask(0177);
1058 #endif
1059         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
1060                 perror("bind");
1061 #ifdef HAVE_CYGWIN
1062                 umask(prev_mask);
1063 #endif
1064                 cleanup_exit(1);
1065         }
1066 #ifdef HAVE_CYGWIN
1067         umask(prev_mask);
1068 #endif
1069         if (listen(sock, 128) < 0) {
1070                 perror("listen");
1071                 cleanup_exit(1);
1072         }
1073
1074         /*
1075          * Fork, and have the parent execute the command, if any, or present
1076          * the socket data.  The child continues as the authentication agent.
1077          */
1078         if (d_flag) {
1079                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1080                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1081                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1082                     SSH_AUTHSOCKET_ENV_NAME);
1083                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1084                 goto skip;
1085         }
1086         pid = fork();
1087         if (pid == -1) {
1088                 perror("fork");
1089                 cleanup_exit(1);
1090         }
1091         if (pid != 0) {         /* Parent - execute the given command. */
1092                 close(sock);
1093                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1094                 if (ac == 0) {
1095                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1096                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1097                             SSH_AUTHSOCKET_ENV_NAME);
1098                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1099                             SSH_AGENTPID_ENV_NAME);
1100                         printf("echo Agent pid %ld;\n", (long)pid);
1101                         exit(0);
1102                 }
1103                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1104                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1105                         perror("setenv");
1106                         exit(1);
1107                 }
1108                 execvp(av[0], av);
1109                 perror(av[0]);
1110                 exit(1);
1111         }
1112         /* child */
1113         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1114
1115         if (setsid() == -1) {
1116                 error("setsid: %s", strerror(errno));
1117                 cleanup_exit(1);
1118         }
1119
1120         (void)chdir("/");
1121         close(0);
1122         close(1);
1123         close(2);
1124
1125 #ifdef HAVE_SETRLIMIT
1126         /* deny core dumps, since memory contains unencrypted private keys */
1127         rlim.rlim_cur = rlim.rlim_max = 0;
1128         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1129                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1130                 cleanup_exit(1);
1131         }
1132 #endif
1133
1134 skip:
1135         fatal_add_cleanup(cleanup_socket, NULL);
1136         new_socket(AUTH_SOCKET, sock);
1137         if (ac > 0) {
1138                 signal(SIGALRM, check_parent_exists);
1139                 alarm(10);
1140         }
1141         idtab_init();
1142         if (!d_flag)
1143                 signal(SIGINT, SIG_IGN);
1144         signal(SIGPIPE, SIG_IGN);
1145         signal(SIGHUP, cleanup_handler);
1146         signal(SIGTERM, cleanup_handler);
1147         nalloc = 0;
1148
1149         while (1) {
1150                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1151                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1152                         if (errno == EINTR)
1153                                 continue;
1154                         fatal("select: %s", strerror(errno));
1155                 }
1156                 after_select(readsetp, writesetp);
1157         }
1158         /* NOTREACHED */
1159 }