usr.sbin/keyserv/setkey.c

   1 /*
   2  * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
   3  * unrestricted use provided that this legend is included on all tape
   4  * media and as a part of the software program in whole or part.  Users
   5  * may copy or modify Sun RPC without charge, but are not authorized
   6  * to license or distribute it to anyone else except as part of a product or
   7  * program developed by the user.
   8  *
   9  * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
  10  * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
  11  * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
  12  *
  13  * Sun RPC is provided with no support and without any obligation on the
  14  * part of Sun Microsystems, Inc. to assist in its use, correction,
  15  * modification or enhancement.
  16  *
  17  * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
  18  * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
  19  * OR ANY PART THEREOF.
  20  *
  21  * In no event will Sun Microsystems, Inc. be liable for any lost revenue
  22  * or profits or other special, indirect and consequential damages, even if
  23  * Sun has been advised of the possibility of such damages.
  24  *
  25  * Sun Microsystems, Inc.
  26  * 2550 Garcia Avenue
  27  * Mountain View, California  94043
  28  *
  29  * @(#)setkey.c 1.11    94/04/25 SMI
  30  * $FreeBSD: src/usr.sbin/keyserv/setkey.c,v 1.3 1999/08/28 01:16:41 peter Exp $
  31  * $DragonFly: src/usr.sbin/keyserv/setkey.c,v 1.8 2005/01/11 13:22:40 joerg Exp $
  32  */
  33
  34 /*
  35  * Copyright (c) 1986 - 1991 by Sun Microsystems, Inc.
  36  */
  37
  38 /*
  39  * Do the real work of the keyserver.
  40  * Store secret keys. Compute common keys,
  41  * and use them to decrypt and encrypt DES keys.
  42  * Cache the common keys, so the expensive computation is avoided.
  43  */
  44 #include <err.h>
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48 #include <unistd.h>
  49 #include <sys/types.h>
  50 #include <rpc/rpc.h>
  51 #include <rpc/key_prot.h>
  52 #include <rpc/des_crypt.h>
  53 #include <rpc/des.h>
  54 #include <sys/errno.h>
  55 #include "keyserv.h"
  56 #include <openssl/bn.h>
  57 #include <openssl/crypto.h>
  58 #include <openssl/err.h>
  59
  60 static BIGNUM *modulus;
  61 static char *fetchsecretkey( uid_t );
  62 static void writecache( char *, char *, des_block * );
  63 static int readcache( char *, char *, des_block * );
  64 static void extractdeskey ( BIGNUM *, des_block * );
  65 static int storesecretkey( uid_t, keybuf );
  66 static keystatus pk_crypt( uid_t, char *, netobj *, des_block *, int);
  67 static int nodefaultkeys = 0;
  68
  69
  70 /*
  71  * prohibit the nobody key on this machine k (the -d flag)
  72  */
  73 void
  74 pk_nodefaultkeys(void)
  75 {
  76         nodefaultkeys = 1;
  77 }
  78
  79 /*
  80  * Set the modulus for all our Diffie-Hellman operations
  81  */
  82 void
  83 setmodulus(char *modx)
  84 {
  85         if (BN_hex2bn(&modulus, modx) == NULL)
  86                 errx(1, "could not convert modulus to BIGNUM: %s",
  87                      ERR_error_string(ERR_get_error(), 0));
  88 }
  89
  90 /*
  91  * Set the secretkey key for this uid
  92  */
  93 keystatus
  94 pk_setkey(uid_t uid, keybuf skey)
  95 {
  96         if (!storesecretkey(uid, skey)) {
  97                 return (KEY_SYSTEMERR);
  98         }
  99         return (KEY_SUCCESS);
 100 }
 101
 102 /*
 103  * Encrypt the key using the public key associated with remote_name and the
 104  * secret key associated with uid.
 105  */
 106 keystatus
 107 pk_encrypt(uid_t uid, char *remote_name, netobj *remote_key, des_block *key)
 108 {
 109         return (pk_crypt(uid, remote_name, remote_key, key, DES_ENCRYPT));
 110 }
 111
 112 /*
 113  * Decrypt the key using the public key associated with remote_name and the
 114  * secret key associated with uid.
 115  */
 116 keystatus
 117 pk_decrypt(uid_t uid, char *remote_name, netobj *remote_key, des_block *key)
 118 {
 119         return (pk_crypt(uid, remote_name, remote_key, key, DES_DECRYPT));
 120 }
 121
 122 static int store_netname( uid_t, key_netstarg * );
 123 static int fetch_netname( uid_t, key_netstarg * );
 124
 125 keystatus
 126 pk_netput(uid_t uid, key_netstarg *netstore)
 127 {
 128         if (!store_netname(uid, netstore)) {
 129                 return (KEY_SYSTEMERR);
 130         }
 131         return (KEY_SUCCESS);
 132 }
 133
 134 keystatus
 135 pk_netget(uid_t uid, key_netstarg *netstore)
 136 {
 137         if (!fetch_netname(uid, netstore)) {
 138                 return (KEY_SYSTEMERR);
 139         }
 140         return (KEY_SUCCESS);
 141 }
 142
 143
 144 /*
 145  * Do the work of pk_encrypt && pk_decrypt
 146  */
 147 static keystatus
 148 pk_crypt(uid_t uid, char *remote_name, netobj *remote_key, des_block *key,
 149          int mode)
 150 {
 151         char *xsecret;
 152         char xpublic[1024];
 153         char xsecret_hold[1024];
 154         des_block deskey;
 155         int error;
 156         BIGNUM *public, *secret, *common;
 157         BN_CTX *ctx;
 158         char zero[8];
 159
 160         xsecret = fetchsecretkey(uid);
 161         if (xsecret == NULL || xsecret[0] == 0) {
 162                 memset(zero, 0, sizeof (zero));
 163                 xsecret = xsecret_hold;
 164                 if (nodefaultkeys)
 165                         return (KEY_NOSECRET);
 166
 167                 if (!getsecretkey("nobody", xsecret, zero) || xsecret[0] == 0) {
 168                         return (KEY_NOSECRET);
 169                 }
 170         }
 171         if (remote_key) {
 172                 memcpy(xpublic, remote_key->n_bytes, remote_key->n_len);
 173         } else {
 174                 bzero((char *)&xpublic, sizeof(xpublic));
 175                 if (!getpublickey(remote_name, xpublic)) {
 176                         if (nodefaultkeys || !getpublickey("nobody", xpublic))
 177                                 return (KEY_UNKNOWN);
 178                 }
 179         }
 180
 181         if (!readcache(xpublic, xsecret, &deskey)) {
 182                 if ((ctx = BN_CTX_new()) == NULL)
 183                         return (KEY_SYSTEMERR);
 184                 if (BN_hex2bn(&public, xpublic) == NULL) {
 185                         BN_CTX_free(ctx);
 186                         return (KEY_SYSTEMERR);
 187                 }
 188                 if (BN_hex2bn(&secret, xsecret) == NULL) {
 189                         BN_free(public);
 190                         BN_CTX_free(ctx);
 191                         return (KEY_SYSTEMERR);
 192                 }
 193
 194                 if ((common = BN_new()) == NULL) {
 195                         BN_free(secret);
 196                         BN_free(public);
 197                         BN_CTX_free(ctx);
 198                         return (KEY_SYSTEMERR);
 199                 }
 200                 BN_zero(common);
 201                 BN_mod_exp(common, public, secret, modulus, ctx);
 202                 extractdeskey(common, &deskey);
 203                 writecache(xpublic, xsecret, &deskey);
 204                 BN_free(secret);
 205                 BN_free(public);
 206                 BN_free(common);
 207                 BN_CTX_free(ctx);
 208         }
 209         error = ecb_crypt((char *)&deskey, (char *)key, sizeof (des_block),
 210                 DES_HW | mode);
 211         if (DES_FAILED(error)) {
 212                 return (KEY_SYSTEMERR);
 213         }
 214         return (KEY_SUCCESS);
 215 }
 216
 217 keystatus
 218 pk_get_conv_key(uid_t uid, keybuf xpublic, cryptkeyres *result)
 219 {
 220         char *xsecret;
 221         char xsecret_hold[1024];
 222         BIGNUM *public, *secret, *common;
 223         BN_CTX *ctx;
 224         char zero[8];
 225
 226
 227         xsecret = fetchsecretkey(uid);
 228
 229         if (xsecret == NULL || xsecret[0] == 0) {
 230                 memset(zero, 0, sizeof (zero));
 231                 xsecret = xsecret_hold;
 232                 if (nodefaultkeys)
 233                         return (KEY_NOSECRET);
 234
 235                 if (!getsecretkey("nobody", xsecret, zero) ||
 236                         xsecret[0] == 0)
 237                         return (KEY_NOSECRET);
 238         }
 239
 240         if (!readcache(xpublic, xsecret, &result->cryptkeyres_u.deskey)) {
 241                 if ((ctx = BN_CTX_new()) == NULL)
 242                         return (KEY_SYSTEMERR);
 243                 if (BN_hex2bn(&public, xpublic) == NULL) {
 244                         BN_CTX_free(ctx);
 245                         return (KEY_SYSTEMERR);
 246                 }
 247                 if (BN_hex2bn(&secret, xsecret) == NULL) {
 248                         BN_free(public);
 249                         BN_CTX_free(ctx);
 250                         return (KEY_SYSTEMERR);
 251                 }
 252
 253                 if ((common = BN_new()) == NULL) {
 254                         BN_free(secret);
 255                         BN_free(public);
 256                         BN_CTX_free(ctx);
 257                         return (KEY_SYSTEMERR);
 258                 }
 259                 BN_zero(common);
 260                 BN_mod_exp(common, public, secret, modulus, ctx);
 261
 262                 extractdeskey(common, &result->cryptkeyres_u.deskey);
 263                 writecache(xpublic, xsecret, &result->cryptkeyres_u.deskey);
 264                 BN_free(secret);
 265                 BN_free(public);
 266                 BN_free(common);
 267                 BN_CTX_free(ctx);
 268         }
 269
 270         return (KEY_SUCCESS);
 271 }
 272
 273 /*
 274  * Choose middle 64 bits of the common key to use as our des key, possibly
 275  * overwriting the lower order bits by setting parity.
 276  */
 277 static void
 278 extractdeskey(BIGNUM *ck, des_block *deskey)
 279 {
 280         BIGNUM *a;
 281         int i;
 282         BN_ULONG r, base = (1 << 8);
 283         char *k;
 284
 285         if ((a = BN_dup(ck)) == NULL)
 286                 errx(1, "could not copy BIGNUM");
 287
 288         for (i = 0; i < ((KEYSIZE - 64) / 2) / 8; i++) {
 289                 r = BN_div_word(a, base);
 290         }
 291         k = deskey->c;
 292         for (i = 0; i < 8; i++) {
 293                 r = BN_div_word(a, base);
 294                 *k++ = r;
 295         }
 296         BN_free(a);
 297         des_setparity((char *)deskey);
 298 }
 299
 300 /*
 301  * Key storage management
 302  */
 303
 304 #define KEY_ONLY 0
 305 #define KEY_NAME 1
 306 struct secretkey_netname_list {
 307         uid_t uid;
 308         key_netstarg keynetdata;
 309         u_char sc_flag;
 310         struct secretkey_netname_list *next;
 311 };
 312
 313
 314
 315 static struct secretkey_netname_list *g_secretkey_netname;
 316
 317 /*
 318  * Store the keys and netname for this uid
 319  */
 320 static int
 321 store_netname(uid_t uid, key_netstarg *netstore)
 322 {
 323         struct secretkey_netname_list *new;
 324         struct secretkey_netname_list **l;
 325
 326         for (l = &g_secretkey_netname; *l != NULL && (*l)->uid != uid;
 327                         l = &(*l)->next) {
 328         }
 329         if (*l == NULL) {
 330                 new = (struct secretkey_netname_list *)malloc(sizeof (*new));
 331                 if (new == NULL) {
 332                         return (0);
 333                 }
 334                 new->uid = uid;
 335                 new->next = NULL;
 336                 *l = new;
 337         } else {
 338                 new = *l;
 339                 if (new->keynetdata.st_netname)
 340                         free(new->keynetdata.st_netname);
 341         }
 342         memcpy(new->keynetdata.st_priv_key, netstore->st_priv_key,
 343                 HEXKEYBYTES);
 344         memcpy(new->keynetdata.st_pub_key, netstore->st_pub_key, HEXKEYBYTES);
 345
 346         if (netstore->st_netname)
 347                 new->keynetdata.st_netname = strdup(netstore->st_netname);
 348         else
 349                 new->keynetdata.st_netname = (char *)NULL;
 350         new->sc_flag = KEY_NAME;
 351         return (1);
 352
 353 }
 354
 355 /*
 356  * Fetch the keys and netname for this uid
 357  */
 358
 359 static int
 360 fetch_netname(uid_t uid, struct key_netstarg *key_netst)
 361 {
 362         struct secretkey_netname_list *l;
 363
 364         for (l = g_secretkey_netname; l != NULL; l = l->next) {
 365                 if ((l->uid == uid) && (l->sc_flag == KEY_NAME)){
 366
 367                         memcpy(key_netst->st_priv_key,
 368                                 l->keynetdata.st_priv_key, HEXKEYBYTES);
 369
 370                         memcpy(key_netst->st_pub_key,
 371                                 l->keynetdata.st_pub_key, HEXKEYBYTES);
 372
 373                         if (l->keynetdata.st_netname)
 374                                 key_netst->st_netname =
 375                                         strdup(l->keynetdata.st_netname);
 376                         else
 377                                 key_netst->st_netname = NULL;
 378                 return (1);
 379                 }
 380         }
 381
 382         return (0);
 383 }
 384
 385 static char *
 386 fetchsecretkey(uid_t uid)
 387 {
 388         struct secretkey_netname_list *l;
 389
 390         for (l = g_secretkey_netname; l != NULL; l = l->next) {
 391                 if (l->uid == uid) {
 392                         return (l->keynetdata.st_priv_key);
 393                 }
 394         }
 395         return (NULL);
 396 }
 397
 398 /*
 399  * Store the secretkey for this uid
 400  */
 401 static int
 402 storesecretkey(uid_t uid, keybuf key)
 403 {
 404         struct secretkey_netname_list *new;
 405         struct secretkey_netname_list **l;
 406
 407         for (l = &g_secretkey_netname; *l != NULL && (*l)->uid != uid;
 408                         l = &(*l)->next) {
 409         }
 410         if (*l == NULL) {
 411                 new = (struct secretkey_netname_list *) malloc(sizeof (*new));
 412                 if (new == NULL) {
 413                         return (0);
 414                 }
 415                 new->uid = uid;
 416                 new->sc_flag = KEY_ONLY;
 417                 memset(new->keynetdata.st_pub_key, 0, HEXKEYBYTES);
 418                 new->keynetdata.st_netname = NULL;
 419                 new->next = NULL;
 420                 *l = new;
 421         } else {
 422                 new = *l;
 423         }
 424
 425         memcpy(new->keynetdata.st_priv_key, key,
 426                 HEXKEYBYTES);
 427         return (1);
 428 }
 429
 430 static int
 431 hexdigit(int val)
 432 {
 433         return ("0123456789abcdef"[val]);
 434 }
 435
 436 void
 437 bin2hex(unsigned char *bin, unsigned char *hex, int size)
 438 {
 439         int i;
 440
 441         for (i = 0; i < size; i++) {
 442                 *hex++ = hexdigit(*bin >> 4);
 443                 *hex++ = hexdigit(*bin++ & 0xf);
 444         }
 445 }
 446
 447 static int
 448 hexval(char dig)
 449 {
 450         if ('0' <= dig && dig <= '9') {
 451                 return (dig - '0');
 452         } else if ('a' <= dig && dig <= 'f') {
 453                 return (dig - 'a' + 10);
 454         } else if ('A' <= dig && dig <= 'F') {
 455                 return (dig - 'A' + 10);
 456         } else {
 457                 return (-1);
 458         }
 459 }
 460
 461 void
 462 hex2bin(unsigned char *hex, unsigned char *bin, int size)
 463 {
 464         int i;
 465
 466         for (i = 0; i < size; i++) {
 467                 *bin = hexval(*hex++) << 4;
 468                 *bin++ |= hexval(*hex++);
 469         }
 470 }
 471
 472 /*
 473  * Exponential caching management
 474  */
 475 struct cachekey_list {
 476         keybuf secret;
 477         keybuf public;
 478         des_block deskey;
 479         struct cachekey_list *next;
 480 };
 481 static struct cachekey_list *g_cachedkeys;
 482
 483 /*
 484  * cache result of expensive multiple precision exponential operation
 485  */
 486 static void
 487 writecache(char *pub, char *sec, des_block *deskey)
 488 {
 489         struct cachekey_list *new;
 490
 491         new = (struct cachekey_list *) malloc(sizeof (struct cachekey_list));
 492         if (new == NULL) {
 493                 return;
 494         }
 495         memcpy(new->public, pub, sizeof (keybuf));
 496         memcpy(new->secret, sec, sizeof (keybuf));
 497         new->deskey = *deskey;
 498         new->next = g_cachedkeys;
 499         g_cachedkeys = new;
 500 }
 501
 502 /*
 503  * Try to find the common key in the cache
 504  */
 505 static int
 506 readcache(char *pub, char *sec, des_block *deskey)
 507 {
 508         struct cachekey_list *found;
 509         struct cachekey_list **l;
 510
 511 #define cachehit(pub, sec, list)        \
 512                 (memcmp(pub, (list)->public, sizeof (keybuf)) == 0 && \
 513                 memcmp(sec, (list)->secret, sizeof (keybuf)) == 0)
 514
 515         for (l = &g_cachedkeys; (*l) != NULL && !cachehit(pub, sec, *l);
 516                 l = &(*l)->next)
 517                 ;
 518         if ((*l) == NULL) {
 519                 return (0);
 520         }
 521         found = *l;
 522         (*l) = (*l)->next;
 523         found->next = g_cachedkeys;
 524         g_cachedkeys = found;
 525         *deskey = found->deskey;
 526         return (1);
 527 }