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 1.9 2005/07/17 19:16:35 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         modulus = NULL;
  86         if (BN_hex2bn(&modulus, modx) == NULL)
  87                 errx(1, "could not convert modulus to BIGNUM: %s",
  88                      ERR_error_string(ERR_get_error(), 0));
  89 }
  90
  91 /*
  92  * Set the secretkey key for this uid
  93  */
  94 keystatus
  95 pk_setkey(uid_t uid, keybuf skey)
  96 {
  97         if (!storesecretkey(uid, skey)) {
  98                 return (KEY_SYSTEMERR);
  99         }
 100         return (KEY_SUCCESS);
 101 }
 102
 103 /*
 104  * Encrypt the key using the public key associated with remote_name and the
 105  * secret key associated with uid.
 106  */
 107 keystatus
 108 pk_encrypt(uid_t uid, char *remote_name, netobj *remote_key, des_block *key)
 109 {
 110         return (pk_crypt(uid, remote_name, remote_key, key, DES_ENCRYPT));
 111 }
 112
 113 /*
 114  * Decrypt the key using the public key associated with remote_name and the
 115  * secret key associated with uid.
 116  */
 117 keystatus
 118 pk_decrypt(uid_t uid, char *remote_name, netobj *remote_key, des_block *key)
 119 {
 120         return (pk_crypt(uid, remote_name, remote_key, key, DES_DECRYPT));
 121 }
 122
 123 static int store_netname( uid_t, key_netstarg * );
 124 static int fetch_netname( uid_t, key_netstarg * );
 125
 126 keystatus
 127 pk_netput(uid_t uid, key_netstarg *netstore)
 128 {
 129         if (!store_netname(uid, netstore)) {
 130                 return (KEY_SYSTEMERR);
 131         }
 132         return (KEY_SUCCESS);
 133 }
 134
 135 keystatus
 136 pk_netget(uid_t uid, key_netstarg *netstore)
 137 {
 138         if (!fetch_netname(uid, netstore)) {
 139                 return (KEY_SYSTEMERR);
 140         }
 141         return (KEY_SUCCESS);
 142 }
 143
 144
 145 /*
 146  * Do the work of pk_encrypt && pk_decrypt
 147  */
 148 static keystatus
 149 pk_crypt(uid_t uid, char *remote_name, netobj *remote_key, des_block *key,
 150          int mode)
 151 {
 152         char *xsecret;
 153         char xpublic[1024];
 154         char xsecret_hold[1024];
 155         des_block deskey;
 156         int error;
 157         BIGNUM *public, *secret, *common;
 158         BN_CTX *ctx;
 159         char zero[8];
 160
 161         xsecret = fetchsecretkey(uid);
 162         if (xsecret == NULL || xsecret[0] == 0) {
 163                 memset(zero, 0, sizeof (zero));
 164                 xsecret = xsecret_hold;
 165                 if (nodefaultkeys)
 166                         return (KEY_NOSECRET);
 167
 168                 if (!getsecretkey("nobody", xsecret, zero) || xsecret[0] == 0) {
 169                         return (KEY_NOSECRET);
 170                 }
 171         }
 172         if (remote_key) {
 173                 memcpy(xpublic, remote_key->n_bytes, remote_key->n_len);
 174         } else {
 175                 bzero((char *)&xpublic, sizeof(xpublic));
 176                 if (!getpublickey(remote_name, xpublic)) {
 177                         if (nodefaultkeys || !getpublickey("nobody", xpublic))
 178                                 return (KEY_UNKNOWN);
 179                 }
 180         }
 181
 182         if (!readcache(xpublic, xsecret, &deskey)) {
 183                 if ((ctx = BN_CTX_new()) == NULL)
 184                         return (KEY_SYSTEMERR);
 185                 public = NULL;
 186                 if (BN_hex2bn(&public, xpublic) == NULL) {
 187                         BN_CTX_free(ctx);
 188                         return (KEY_SYSTEMERR);
 189                 }
 190                 secret = NULL;
 191                 if (BN_hex2bn(&secret, xsecret) == NULL) {
 192                         BN_free(public);
 193                         BN_CTX_free(ctx);
 194                         return (KEY_SYSTEMERR);
 195                 }
 196
 197                 if ((common = BN_new()) == NULL) {
 198                         BN_free(secret);
 199                         BN_free(public);
 200                         BN_CTX_free(ctx);
 201                         return (KEY_SYSTEMERR);
 202                 }
 203                 BN_zero(common);
 204                 BN_mod_exp(common, public, secret, modulus, ctx);
 205                 extractdeskey(common, &deskey);
 206                 writecache(xpublic, xsecret, &deskey);
 207                 BN_free(secret);
 208                 BN_free(public);
 209                 BN_free(common);
 210                 BN_CTX_free(ctx);
 211         }
 212         error = ecb_crypt((char *)&deskey, (char *)key, sizeof (des_block),
 213                 DES_HW | mode);
 214         if (DES_FAILED(error)) {
 215                 return (KEY_SYSTEMERR);
 216         }
 217         return (KEY_SUCCESS);
 218 }
 219
 220 keystatus
 221 pk_get_conv_key(uid_t uid, keybuf xpublic, cryptkeyres *result)
 222 {
 223         char *xsecret;
 224         char xsecret_hold[1024];
 225         BIGNUM *public, *secret, *common;
 226         BN_CTX *ctx;
 227         char zero[8];
 228
 229
 230         xsecret = fetchsecretkey(uid);
 231
 232         if (xsecret == NULL || xsecret[0] == 0) {
 233                 memset(zero, 0, sizeof (zero));
 234                 xsecret = xsecret_hold;
 235                 if (nodefaultkeys)
 236                         return (KEY_NOSECRET);
 237
 238                 if (!getsecretkey("nobody", xsecret, zero) ||
 239                         xsecret[0] == 0)
 240                         return (KEY_NOSECRET);
 241         }
 242
 243         if (!readcache(xpublic, xsecret, &result->cryptkeyres_u.deskey)) {
 244                 if ((ctx = BN_CTX_new()) == NULL)
 245                         return (KEY_SYSTEMERR);
 246                 public = NULL;
 247                 if (BN_hex2bn(&public, xpublic) == NULL) {
 248                         BN_CTX_free(ctx);
 249                         return (KEY_SYSTEMERR);
 250                 }
 251                 secret = NULL;
 252                 if (BN_hex2bn(&secret, xsecret) == NULL) {
 253                         BN_free(public);
 254                         BN_CTX_free(ctx);
 255                         return (KEY_SYSTEMERR);
 256                 }
 257
 258                 if ((common = BN_new()) == NULL) {
 259                         BN_free(secret);
 260                         BN_free(public);
 261                         BN_CTX_free(ctx);
 262                         return (KEY_SYSTEMERR);
 263                 }
 264                 BN_zero(common);
 265                 BN_mod_exp(common, public, secret, modulus, ctx);
 266
 267                 extractdeskey(common, &result->cryptkeyres_u.deskey);
 268                 writecache(xpublic, xsecret, &result->cryptkeyres_u.deskey);
 269                 BN_free(secret);
 270                 BN_free(public);
 271                 BN_free(common);
 272                 BN_CTX_free(ctx);
 273         }
 274
 275         return (KEY_SUCCESS);
 276 }
 277
 278 /*
 279  * Choose middle 64 bits of the common key to use as our des key, possibly
 280  * overwriting the lower order bits by setting parity.
 281  */
 282 static void
 283 extractdeskey(BIGNUM *ck, des_block *deskey)
 284 {
 285         BIGNUM *a;
 286         int i;
 287         BN_ULONG r, base = (1 << 8);
 288         char *k;
 289
 290         if ((a = BN_dup(ck)) == NULL)
 291                 errx(1, "could not copy BIGNUM");
 292
 293         for (i = 0; i < ((KEYSIZE - 64) / 2) / 8; i++) {
 294                 r = BN_div_word(a, base);
 295         }
 296         k = deskey->c;
 297         for (i = 0; i < 8; i++) {
 298                 r = BN_div_word(a, base);
 299                 *k++ = r;
 300         }
 301         BN_free(a);
 302         des_setparity((char *)deskey);
 303 }
 304
 305 /*
 306  * Key storage management
 307  */
 308
 309 #define KEY_ONLY 0
 310 #define KEY_NAME 1
 311 struct secretkey_netname_list {
 312         uid_t uid;
 313         key_netstarg keynetdata;
 314         u_char sc_flag;
 315         struct secretkey_netname_list *next;
 316 };
 317
 318
 319
 320 static struct secretkey_netname_list *g_secretkey_netname;
 321
 322 /*
 323  * Store the keys and netname for this uid
 324  */
 325 static int
 326 store_netname(uid_t uid, key_netstarg *netstore)
 327 {
 328         struct secretkey_netname_list *new;
 329         struct secretkey_netname_list **l;
 330
 331         for (l = &g_secretkey_netname; *l != NULL && (*l)->uid != uid;
 332                         l = &(*l)->next) {
 333         }
 334         if (*l == NULL) {
 335                 new = (struct secretkey_netname_list *)malloc(sizeof (*new));
 336                 if (new == NULL) {
 337                         return (0);
 338                 }
 339                 new->uid = uid;
 340                 new->next = NULL;
 341                 *l = new;
 342         } else {
 343                 new = *l;
 344                 if (new->keynetdata.st_netname)
 345                         free(new->keynetdata.st_netname);
 346         }
 347         memcpy(new->keynetdata.st_priv_key, netstore->st_priv_key,
 348                 HEXKEYBYTES);
 349         memcpy(new->keynetdata.st_pub_key, netstore->st_pub_key, HEXKEYBYTES);
 350
 351         if (netstore->st_netname)
 352                 new->keynetdata.st_netname = strdup(netstore->st_netname);
 353         else
 354                 new->keynetdata.st_netname = (char *)NULL;
 355         new->sc_flag = KEY_NAME;
 356         return (1);
 357
 358 }
 359
 360 /*
 361  * Fetch the keys and netname for this uid
 362  */
 363
 364 static int
 365 fetch_netname(uid_t uid, struct key_netstarg *key_netst)
 366 {
 367         struct secretkey_netname_list *l;
 368
 369         for (l = g_secretkey_netname; l != NULL; l = l->next) {
 370                 if ((l->uid == uid) && (l->sc_flag == KEY_NAME)){
 371
 372                         memcpy(key_netst->st_priv_key,
 373                                 l->keynetdata.st_priv_key, HEXKEYBYTES);
 374
 375                         memcpy(key_netst->st_pub_key,
 376                                 l->keynetdata.st_pub_key, HEXKEYBYTES);
 377
 378                         if (l->keynetdata.st_netname)
 379                                 key_netst->st_netname =
 380                                         strdup(l->keynetdata.st_netname);
 381                         else
 382                                 key_netst->st_netname = NULL;
 383                 return (1);
 384                 }
 385         }
 386
 387         return (0);
 388 }
 389
 390 static char *
 391 fetchsecretkey(uid_t uid)
 392 {
 393         struct secretkey_netname_list *l;
 394
 395         for (l = g_secretkey_netname; l != NULL; l = l->next) {
 396                 if (l->uid == uid) {
 397                         return (l->keynetdata.st_priv_key);
 398                 }
 399         }
 400         return (NULL);
 401 }
 402
 403 /*
 404  * Store the secretkey for this uid
 405  */
 406 static int
 407 storesecretkey(uid_t uid, keybuf key)
 408 {
 409         struct secretkey_netname_list *new;
 410         struct secretkey_netname_list **l;
 411
 412         for (l = &g_secretkey_netname; *l != NULL && (*l)->uid != uid;
 413                         l = &(*l)->next) {
 414         }
 415         if (*l == NULL) {
 416                 new = (struct secretkey_netname_list *) malloc(sizeof (*new));
 417                 if (new == NULL) {
 418                         return (0);
 419                 }
 420                 new->uid = uid;
 421                 new->sc_flag = KEY_ONLY;
 422                 memset(new->keynetdata.st_pub_key, 0, HEXKEYBYTES);
 423                 new->keynetdata.st_netname = NULL;
 424                 new->next = NULL;
 425                 *l = new;
 426         } else {
 427                 new = *l;
 428         }
 429
 430         memcpy(new->keynetdata.st_priv_key, key,
 431                 HEXKEYBYTES);
 432         return (1);
 433 }
 434
 435 static int
 436 hexdigit(int val)
 437 {
 438         return ("0123456789abcdef"[val]);
 439 }
 440
 441 void
 442 bin2hex(unsigned char *bin, unsigned char *hex, int size)
 443 {
 444         int i;
 445
 446         for (i = 0; i < size; i++) {
 447                 *hex++ = hexdigit(*bin >> 4);
 448                 *hex++ = hexdigit(*bin++ & 0xf);
 449         }
 450 }
 451
 452 static int
 453 hexval(char dig)
 454 {
 455         if ('0' <= dig && dig <= '9') {
 456                 return (dig - '0');
 457         } else if ('a' <= dig && dig <= 'f') {
 458                 return (dig - 'a' + 10);
 459         } else if ('A' <= dig && dig <= 'F') {
 460                 return (dig - 'A' + 10);
 461         } else {
 462                 return (-1);
 463         }
 464 }
 465
 466 void
 467 hex2bin(unsigned char *hex, unsigned char *bin, int size)
 468 {
 469         int i;
 470
 471         for (i = 0; i < size; i++) {
 472                 *bin = hexval(*hex++) << 4;
 473                 *bin++ |= hexval(*hex++);
 474         }
 475 }
 476
 477 /*
 478  * Exponential caching management
 479  */
 480 struct cachekey_list {
 481         keybuf secret;
 482         keybuf public;
 483         des_block deskey;
 484         struct cachekey_list *next;
 485 };
 486 static struct cachekey_list *g_cachedkeys;
 487
 488 /*
 489  * cache result of expensive multiple precision exponential operation
 490  */
 491 static void
 492 writecache(char *pub, char *sec, des_block *deskey)
 493 {
 494         struct cachekey_list *new;
 495
 496         new = (struct cachekey_list *) malloc(sizeof (struct cachekey_list));
 497         if (new == NULL) {
 498                 return;
 499         }
 500         memcpy(new->public, pub, sizeof (keybuf));
 501         memcpy(new->secret, sec, sizeof (keybuf));
 502         new->deskey = *deskey;
 503         new->next = g_cachedkeys;
 504         g_cachedkeys = new;
 505 }
 506
 507 /*
 508  * Try to find the common key in the cache
 509  */
 510 static int
 511 readcache(char *pub, char *sec, des_block *deskey)
 512 {
 513         struct cachekey_list *found;
 514         struct cachekey_list **l;
 515
 516 #define cachehit(pub, sec, list)        \
 517                 (memcmp(pub, (list)->public, sizeof (keybuf)) == 0 && \
 518                 memcmp(sec, (list)->secret, sizeof (keybuf)) == 0)
 519
 520         for (l = &g_cachedkeys; (*l) != NULL && !cachehit(pub, sec, *l);
 521                 l = &(*l)->next)
 522                 ;
 523         if ((*l) == NULL) {
 524                 return (0);
 525         }
 526         found = *l;
 527         (*l) = (*l)->next;
 528         found->next = g_cachedkeys;
 529         g_cachedkeys = found;
 530         *deskey = found->deskey;
 531         return (1);
 532 }