usr.sbin/keyserv/crypt_server.c

   1 /*
   2  * Copyright (c) 1996
   3  *      Bill Paul <wpaul@ctr.columbia.edu>.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by Bill Paul.
  16  * 4. Neither the name of the author nor the names of any co-contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL Bill Paul OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #include <sys/types.h>
  34 #include <sys/param.h>
  35 #include <dirent.h>
  36 #include <dlfcn.h>
  37 #include <err.h>
  38 #include <stdio.h>
  39 #include <stdlib.h>
  40 #include <string.h>
  41 #include <rpc/des_crypt.h>
  42 #include <rpc/des.h>
  43 #include "crypt.h"
  44
  45 #ifndef lint
  46 static const char rcsid[] =
  47   "$FreeBSD$";
  48 #endif /* not lint */
  49
  50 /*
  51  * The U.S. government stupidly believes that a) it can keep strong
  52  * crypto code a secret and b) that doing so somehow protects national
  53  * interests. It's wrong on both counts, but until it listens to reason
  54  * we have to make certain compromises so it doesn't have an excuse to
  55  * throw us in federal prison.
  56  *
  57  * Consequently, the core OS ships without DES support, and keyserv
  58  * defaults to using ARCFOUR with only a 40 bit key, just like nutscrape.
  59  * This breaks compatibility with Secure RPC on other systems, but it
  60  * allows Secure RPC to work between FreeBSD systems that don't have the
  61  * DES package installed without throwing security totally out the window.
  62  *
  63  * In order to avoid having to supply two versions of keyserv (one with
  64  * DES and one without), we use dlopen() and friends to load libdes.so
  65  * into our address space at runtime. We check for the presence of
  66  * /usr/lib/libdes.so.3.0 at startup and load it if we find it. If we
  67  * can't find it, or the __des_crypt symbol doesn't exist, we fall back
  68  * to the ARCFOUR encryption code. The user can specify another path using
  69  * the -p flag.
  70  */
  71
  72  /* arcfour.h */
  73 typedef struct arcfour_key
  74 {
  75    unsigned char state[256];
  76    unsigned char x;
  77    unsigned char y;
  78 } arcfour_key;
  79
  80 static void prepare_key(unsigned char *key_data_ptr,int key_data_len,
  81                  arcfour_key *key);
  82 static void arcfour(unsigned char *buffer_ptr,int buffer_len,arcfour_key * key);
  83 static void swap_byte(unsigned char *a, unsigned char *b);
  84
  85 static void prepare_key(unsigned char *key_data_ptr, int key_data_len,
  86                  arcfour_key *key)
  87 {
  88    unsigned char index1;
  89    unsigned char index2;
  90    unsigned char* state;
  91    short counter;
  92
  93    state = &key->state[0];
  94    for(counter = 0; counter < 256; counter++)
  95    state[counter] = counter;
  96    key->x = 0;
  97    key->y = 0;
  98    index1 = 0;
  99    index2 = 0;
 100    for(counter = 0; counter < 256; counter++)
 101    {
 102       index2 = (key_data_ptr[index1] + state[counter] +
 103                 index2) % 256;
 104       swap_byte(&state[counter], &state[index2]);
 105
 106       index1 = (index1 + 1) % key_data_len;
 107    }
 108 }
 109
 110 static void arcfour(unsigned char *buffer_ptr, int buffer_len, arcfour_key *key)
 111 {
 112    unsigned char x;
 113    unsigned char y;
 114    unsigned char* state;
 115    unsigned char xorIndex;
 116    short counter;
 117
 118    x = key->x;
 119    y = key->y;
 120
 121    state = &key->state[0];
 122    for(counter = 0; counter < buffer_len; counter ++)
 123    {
 124       x = (x + 1) % 256;
 125       y = (state[x] + y) % 256;
 126       swap_byte(&state[x], &state[y]);
 127
 128       xorIndex = (state[x] + state[y]) % 256;
 129
 130       buffer_ptr[counter] ^= state[xorIndex];
 131    }
 132    key->x = x;
 133    key->y = y;
 134 }
 135
 136 static void swap_byte(unsigned char *a, unsigned char *b)
 137 {
 138    unsigned char swapByte;
 139
 140    swapByte = *a;
 141    *a = *b;
 142    *b = swapByte;
 143 }
 144
 145 /* Dummy _des_crypt function that uses ARCFOUR with a 40 bit key */
 146 int _arcfour_crypt(buf, len, desp)
 147         char *buf;
 148         int len;
 149         struct desparams *desp;
 150 {
 151         struct arcfour_key arcfourk;
 152
 153         /*
 154          * U.S. government anti-crypto weasels take
 155          * note: although we are supplied with a 64 bit
 156          * key, we're only passing 40 bits to the ARCFOUR
 157          * encryption code. So there.
 158          */
 159         prepare_key(desp->des_key, 5, &arcfourk);
 160         arcfour(buf, len, &arcfourk);
 161
 162         return(DESERR_NOHWDEVICE);
 163 }
 164
 165 int (*_my_crypt)(char *, int, struct desparams *) = NULL;
 166
 167 static void *dlhandle;
 168
 169 #ifndef _PATH_USRLIB
 170 #define _PATH_USRLIB "/usr/lib"
 171 #endif
 172
 173 #ifndef LIBCRYPTO
 174 #define LIBCRYPTO "libcrypto.so.2"
 175 #endif
 176
 177 void load_des(warn, libpath)
 178         int warn;
 179         char *libpath;
 180 {
 181         char dlpath[MAXPATHLEN];
 182
 183         if (libpath == NULL) {
 184                 snprintf(dlpath, sizeof(dlpath), "%s/%s", _PATH_USRLIB, LIBCRYPTO);
 185         } else
 186                 snprintf(dlpath, sizeof(dlpath), "%s", libpath);
 187
 188         if (dlpath != NULL && (dlhandle = dlopen(dlpath, 0444)) != NULL)
 189                 _my_crypt = (int (*)())dlsym(dlhandle, "_des_crypt");
 190
 191         if (_my_crypt == NULL) {
 192                 if (dlhandle != NULL)
 193                         dlclose(dlhandle);
 194                 _my_crypt = &_arcfour_crypt;
 195                 if (warn) {
 196                         printf ("DES support disabled -- using ARCFOUR instead.\n");
 197                         printf ("Warning: ARCFOUR cipher is not compatible with ");
 198                         printf ("other Secure RPC implementations.\nInstall ");
 199                         printf ("the FreeBSD 'des' distribution to enable");
 200                         printf (" DES encryption.\n");
 201                 }
 202         } else {
 203                 if (warn) {
 204                         printf ("DES support enabled\n");
 205                         printf ("Using %s shared object.\n", dlpath);
 206                 }
 207         }
 208
 209         return;
 210 }
 211
 212 desresp *
 213 des_crypt_1_svc(desargs *argp, struct svc_req *rqstp)
 214 {
 215         static desresp  result;
 216         struct desparams dparm;
 217
 218         if (argp->desbuf.desbuf_len > DES_MAXDATA) {
 219                 result.stat = DESERR_BADPARAM;
 220                 return(&result);
 221         }
 222
 223
 224         bcopy(argp->des_key, dparm.des_key, 8);
 225         bcopy(argp->des_ivec, dparm.des_ivec, 8);
 226         dparm.des_mode = argp->des_mode;
 227         dparm.des_dir = argp->des_dir;
 228 #ifdef BROKEN_DES
 229         dparm.UDES.UDES_buf = argp->desbuf.desbuf_val;
 230 #endif
 231
 232         /*
 233          * XXX This compensates for a bug in the libdes Secure RPC
 234          * compat interface. (Actually, there are a couple.) The
 235          * des_ecb_encrypt() routine in libdes only encrypts 8 bytes
 236          * (64 bits) at a time. However, the Sun Secure RPC ecb_crypt()
 237          * routine is supposed to be able to handle buffers up to 8Kbytes.
 238          * The rpc_enc module in libdes ignores this fact and just drops
 239          * the length parameter on the floor, encrypting only the
 240          * first 64 bits of whatever buffer you feed it. We deal with
 241          * this here: if we're using DES encryption, and we're using
 242          * ECB mode, then we make a pass over the entire buffer
 243          * ourselves. Note: the rpc_enc module incorrectly transposes
 244          * the mode flags, so when you ask for CBC mode, you're really
 245          * getting ECB mode.
 246          */
 247 #ifdef BROKEN_DES
 248         if (_my_crypt != &_arcfour_crypt && argp->des_mode == CBC) {
 249 #else
 250         if (_my_crypt != &_arcfour_crypt && argp->des_mode == ECB) {
 251 #endif
 252                 int                     i;
 253                 char                    *dptr;
 254
 255                 for (i = 0; i < argp->desbuf.desbuf_len / 8; i++) {
 256                         dptr = argp->desbuf.desbuf_val;
 257                         dptr += (i * 8);
 258 #ifdef BROKEN_DES
 259                         dparm.UDES.UDES_buf = dptr;
 260 #endif
 261                         result.stat = _my_crypt(dptr, 8, &dparm);
 262                 }
 263         } else {
 264                 result.stat = _my_crypt(argp->desbuf.desbuf_val,
 265                                         argp->desbuf.desbuf_len,
 266                                         &dparm);
 267         }
 268
 269         if (result.stat == DESERR_NONE || result.stat == DESERR_NOHWDEVICE) {
 270                 bcopy(dparm.des_ivec, result.des_ivec, 8);
 271                 result.desbuf.desbuf_len = argp->desbuf.desbuf_len;
 272                 result.desbuf.desbuf_val = argp->desbuf.desbuf_val;
 273         }
 274
 275         return (&result);
 276 }