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  * $FreeBSD: src/usr.sbin/keyserv/crypt_server.c,v 1.6.2.1 2001/07/19 04:21:20 kris Exp $
  33  */
  34
  35 #include <sys/types.h>
  36 #include <sys/param.h>
  37 #include <dirent.h>
  38 #include <dlfcn.h>
  39 #include <err.h>
  40 #include <stdio.h>
  41 #include <stdlib.h>
  42 #include <string.h>
  43 #include <rpc/des_crypt.h>
  44 #include <rpc/des.h>
  45 #include "crypt.h"
  46
  47 /*
  48  * The U.S. government stupidly believes that a) it can keep strong
  49  * crypto code a secret and b) that doing so somehow protects national
  50  * interests. It's wrong on both counts, but until it listens to reason
  51  * we have to make certain compromises so it doesn't have an excuse to
  52  * throw us in federal prison.
  53  *
  54  * Consequently, the core OS ships without DES support, and keyserv
  55  * defaults to using ARCFOUR with only a 40 bit key, just like nutscrape.
  56  * This breaks compatibility with Secure RPC on other systems, but it
  57  * allows Secure RPC to work between FreeBSD systems that don't have the
  58  * DES package installed without throwing security totally out the window.
  59  *
  60  * In order to avoid having to supply two versions of keyserv (one with
  61  * DES and one without), we use dlopen() and friends to load libdes.so
  62  * into our address space at runtime. We check for the presence of
  63  * /usr/lib/libdes.so.3.0 at startup and load it if we find it. If we
  64  * can't find it, or the __des_crypt symbol doesn't exist, we fall back
  65  * to the ARCFOUR encryption code. The user can specify another path using
  66  * the -p flag.
  67  */
  68
  69  /* arcfour.h */
  70 typedef struct arcfour_key
  71 {
  72    unsigned char state[256];
  73    unsigned char x;
  74    unsigned char y;
  75 } arcfour_key;
  76
  77 static void prepare_key(unsigned char *key_data_ptr,int key_data_len,
  78                  arcfour_key *key);
  79 static void arcfour(unsigned char *buffer_ptr,int buffer_len,arcfour_key * key);
  80 static void swap_byte(unsigned char *a, unsigned char *b);
  81
  82 static void
  83 prepare_key(unsigned char *key_data_ptr, int key_data_len, arcfour_key *key)
  84 {
  85    unsigned char index1;
  86    unsigned char index2;
  87    unsigned char* state;
  88    short counter;
  89
  90    state = &key->state[0];
  91    for(counter = 0; counter < 256; counter++)
  92        state[counter] = counter;
  93    key->x = 0;
  94    key->y = 0;
  95    index1 = 0;
  96    index2 = 0;
  97    for(counter = 0; counter < 256; counter++)
  98    {
  99       index2 = (key_data_ptr[index1] + state[counter] +
 100                 index2) % 256;
 101       swap_byte(&state[counter], &state[index2]);
 102
 103       index1 = (index1 + 1) % key_data_len;
 104    }
 105 }
 106
 107 static void
 108 arcfour(unsigned char *buffer_ptr, int buffer_len, arcfour_key *key)
 109 {
 110    unsigned char x;
 111    unsigned char y;
 112    unsigned char* state;
 113    unsigned char xorIndex;
 114    short counter;
 115
 116    x = key->x;
 117    y = key->y;
 118
 119    state = &key->state[0];
 120    for(counter = 0; counter < buffer_len; counter ++)
 121    {
 122       x = (x + 1) % 256;
 123       y = (state[x] + y) % 256;
 124       swap_byte(&state[x], &state[y]);
 125
 126       xorIndex = (state[x] + state[y]) % 256;
 127
 128       buffer_ptr[counter] ^= state[xorIndex];
 129    }
 130    key->x = x;
 131    key->y = y;
 132 }
 133
 134 static void
 135 swap_byte(unsigned char *a, unsigned char *b)
 136 {
 137    unsigned char swapByte;
 138
 139    swapByte = *a;
 140    *a = *b;
 141    *b = swapByte;
 142 }
 143
 144 /* Dummy _des_crypt function that uses ARCFOUR with a 40 bit key */
 145 int
 146 _arcfour_crypt(char *buf, int len, struct desparams *desp)
 147 {
 148         struct arcfour_key arcfourk;
 149
 150         /*
 151          * U.S. government anti-crypto weasels take
 152          * note: although we are supplied with a 64 bit
 153          * key, we're only passing 40 bits to the ARCFOUR
 154          * encryption code. So there.
 155          */
 156         prepare_key(desp->des_key, 5, &arcfourk);
 157         arcfour(buf, len, &arcfourk);
 158
 159         return(DESERR_NOHWDEVICE);
 160 }
 161
 162 int (*_my_crypt)(char *, int, struct desparams *) = NULL;
 163
 164 static void *dlhandle;
 165
 166 #ifndef _PATH_USRLIB
 167 #define _PATH_USRLIB "/usr/lib"
 168 #endif
 169
 170 #ifndef LIBCRYPTO
 171 #define LIBCRYPTO "libcrypto.so.1"
 172 #endif
 173
 174 void
 175 load_des(int warn, char *libpath)
 176 {
 177         char dlpath[MAXPATHLEN];
 178
 179         if (libpath == NULL) {
 180                 snprintf(dlpath, sizeof(dlpath), "%s/%s", _PATH_USRLIB, LIBCRYPTO);
 181         } else
 182                 snprintf(dlpath, sizeof(dlpath), "%s", libpath);
 183
 184         if (dlpath != NULL && (dlhandle = dlopen(dlpath, 0444)) != NULL)
 185                 _my_crypt = (int (*)())dlsym(dlhandle, "_des_crypt");
 186
 187         if (_my_crypt == NULL) {
 188                 if (dlhandle != NULL)
 189                         dlclose(dlhandle);
 190                 _my_crypt = &_arcfour_crypt;
 191                 if (warn) {
 192                         printf ("DES support disabled -- using ARCFOUR instead.\n");
 193                         printf ("Warning: ARCFOUR cipher is not compatible with ");
 194                         printf ("other Secure RPC implementations.\nInstall ");
 195                         printf ("the FreeBSD 'des' distribution to enable");
 196                         printf (" DES encryption.\n");
 197                 }
 198         } else {
 199                 if (warn) {
 200                         printf ("DES support enabled\n");
 201                         printf ("Using %s shared object.\n", dlpath);
 202                 }
 203         }
 204
 205         return;
 206 }
 207
 208 desresp *
 209 des_crypt_1_svc(desargs *argp, struct svc_req *rqstp)
 210 {
 211         static desresp  result;
 212         struct desparams dparm;
 213
 214         if (argp->desbuf.desbuf_len > DES_MAXDATA) {
 215                 result.stat = DESERR_BADPARAM;
 216                 return(&result);
 217         }
 218
 219
 220         bcopy(argp->des_key, dparm.des_key, 8);
 221         bcopy(argp->des_ivec, dparm.des_ivec, 8);
 222         dparm.des_mode = argp->des_mode;
 223         dparm.des_dir = argp->des_dir;
 224 #ifdef BROKEN_DES
 225         dparm.UDES.UDES_buf = argp->desbuf.desbuf_val;
 226 #endif
 227
 228         /*
 229          * XXX This compensates for a bug in the libdes Secure RPC
 230          * compat interface. (Actually, there are a couple.) The
 231          * des_ecb_encrypt() routine in libdes only encrypts 8 bytes
 232          * (64 bits) at a time. However, the Sun Secure RPC ecb_crypt()
 233          * routine is supposed to be able to handle buffers up to 8Kbytes.
 234          * The rpc_enc module in libdes ignores this fact and just drops
 235          * the length parameter on the floor, encrypting only the
 236          * first 64 bits of whatever buffer you feed it. We deal with
 237          * this here: if we're using DES encryption, and we're using
 238          * ECB mode, then we make a pass over the entire buffer
 239          * ourselves. Note: the rpc_enc module incorrectly transposes
 240          * the mode flags, so when you ask for CBC mode, you're really
 241          * getting ECB mode.
 242          */
 243 #ifdef BROKEN_DES
 244         if (_my_crypt != &_arcfour_crypt && argp->des_mode == (des_mode)CBC) {
 245 #else
 246         if (_my_crypt != &_arcfour_crypt && argp->des_mode == ECB) {
 247 #endif
 248                 int                     i;
 249                 char                    *dptr;
 250
 251                 for (i = 0; i < argp->desbuf.desbuf_len / 8; i++) {
 252                         dptr = argp->desbuf.desbuf_val;
 253                         dptr += (i * 8);
 254 #ifdef BROKEN_DES
 255                         dparm.UDES.UDES_buf = dptr;
 256 #endif
 257                         result.stat = _my_crypt(dptr, 8, &dparm);
 258                 }
 259         } else {
 260                 result.stat = _my_crypt(argp->desbuf.desbuf_val,
 261                                         argp->desbuf.desbuf_len,
 262                                         &dparm);
 263         }
 264
 265         if (result.stat == DESERR_NONE || result.stat == DESERR_NOHWDEVICE) {
 266                 bcopy(dparm.des_ivec, result.des_ivec, 8);
 267                 result.desbuf.desbuf_len = argp->desbuf.desbuf_len;
 268                 result.desbuf.desbuf_val = argp->desbuf.desbuf_val;
 269         }
 270
 271         return (&result);
 272 }