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  * $DragonFly: src/usr.sbin/keyserv/crypt_server.c,v 1.6 2005/12/05 01:04:01 swildner Exp $
  34  */
  35
  36 #include <sys/types.h>
  37 #include <sys/param.h>
  38 #include <dirent.h>
  39 #include <dlfcn.h>
  40 #include <err.h>
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43 #include <string.h>
  44 #include <rpc/des_crypt.h>
  45 #include <rpc/des.h>
  46 #include "crypt.h"
  47
  48 /*
  49  * The U.S. government stupidly believes that a) it can keep strong
  50  * crypto code a secret and b) that doing so somehow protects national
  51  * interests. It's wrong on both counts, but until it listens to reason
  52  * we have to make certain compromises so it doesn't have an excuse to
  53  * throw us in federal prison.
  54  *
  55  * Consequently, the core OS ships without DES support, and keyserv
  56  * defaults to using ARCFOUR with only a 40 bit key, just like nutscrape.
  57  * This breaks compatibility with Secure RPC on other systems, but it
  58  * allows Secure RPC to work between FreeBSD systems that don't have the
  59  * DES package installed without throwing security totally out the window.
  60  *
  61  * In order to avoid having to supply two versions of keyserv (one with
  62  * DES and one without), we use dlopen() and friends to load libdes.so
  63  * into our address space at runtime. We check for the presence of
  64  * /usr/lib/libdes.so.3.0 at startup and load it if we find it. If we
  65  * can't find it, or the __des_crypt symbol doesn't exist, we fall back
  66  * to the ARCFOUR encryption code. The user can specify another path using
  67  * the -p flag.
  68  */
  69
  70  /* arcfour.h */
  71 typedef struct arcfour_key
  72 {
  73    unsigned char state[256];
  74    unsigned char x;
  75    unsigned char y;
  76 } arcfour_key;
  77
  78 static void prepare_key(unsigned char *key_data_ptr,int key_data_len,
  79                  arcfour_key *key);
  80 static void arcfour(unsigned char *buffer_ptr,int buffer_len,arcfour_key * key);
  81 static void swap_byte(unsigned char *a, unsigned char *b);
  82
  83 static void
  84 prepare_key(unsigned char *key_data_ptr, int key_data_len, arcfour_key *key)
  85 {
  86    unsigned char index1;
  87    unsigned char index2;
  88    unsigned char* state;
  89    short counter;
  90
  91    state = &key->state[0];
  92    for(counter = 0; counter < 256; counter++)
  93    state[counter] = counter;
  94    key->x = 0;
  95    key->y = 0;
  96    index1 = 0;
  97    index2 = 0;
  98    for(counter = 0; counter < 256; counter++)
  99    {
 100       index2 = (key_data_ptr[index1] + state[counter] +
 101                 index2) % 256;
 102       swap_byte(&state[counter], &state[index2]);
 103
 104       index1 = (index1 + 1) % key_data_len;
 105    }
 106 }
 107
 108 static void
 109 arcfour(unsigned char *buffer_ptr, int buffer_len, arcfour_key *key)
 110 {
 111    unsigned char x;
 112    unsigned char y;
 113    unsigned char* state;
 114    unsigned char xorIndex;
 115    short counter;
 116
 117    x = key->x;
 118    y = key->y;
 119
 120    state = &key->state[0];
 121    for(counter = 0; counter < buffer_len; counter ++)
 122    {
 123       x = (x + 1) % 256;
 124       y = (state[x] + y) % 256;
 125       swap_byte(&state[x], &state[y]);
 126
 127       xorIndex = (state[x] + state[y]) % 256;
 128
 129       buffer_ptr[counter] ^= state[xorIndex];
 130    }
 131    key->x = x;
 132    key->y = y;
 133 }
 134
 135 static void
 136 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
 147 _arcfour_crypt(char *buf, int len, struct desparams *desp)
 148 {
 149         struct arcfour_key arcfourk;
 150
 151         /*
 152          * U.S. government anti-crypto weasels take
 153          * note: although we are supplied with a 64 bit
 154          * key, we're only passing 40 bits to the ARCFOUR
 155          * encryption code. So there.
 156          */
 157         prepare_key(desp->des_key, 5, &arcfourk);
 158         arcfour(buf, len, &arcfourk);
 159
 160         return(DESERR_NOHWDEVICE);
 161 }
 162
 163 int (*_my_crypt)(char *, int, struct desparams *) = NULL;
 164
 165 static void *dlhandle;
 166
 167 #ifndef _PATH_USRLIB
 168 #define _PATH_USRLIB "/usr/lib"
 169 #endif
 170
 171 #ifndef LIBCRYPTO
 172 #define LIBCRYPTO "libcrypto.so.1"
 173 #endif
 174
 175 void
 176 load_des(int warn, char *libpath)
 177 {
 178         char dlpath[MAXPATHLEN];
 179
 180         if (libpath == NULL) {
 181                 snprintf(dlpath, sizeof(dlpath), "%s/%s", _PATH_USRLIB, LIBCRYPTO);
 182         } else
 183                 snprintf(dlpath, sizeof(dlpath), "%s", libpath);
 184
 185         if (dlpath != NULL && (dlhandle = dlopen(dlpath, 0444)) != NULL)
 186                 _my_crypt = (int (*)())dlsym(dlhandle, "_des_crypt");
 187
 188         if (_my_crypt == NULL) {
 189                 if (dlhandle != NULL)
 190                         dlclose(dlhandle);
 191                 _my_crypt = &_arcfour_crypt;
 192                 if (warn) {
 193                         printf ("DES support disabled -- using ARCFOUR instead.\n");
 194                         printf ("Warning: ARCFOUR cipher is not compatible with ");
 195                         printf ("other Secure RPC implementations.\nInstall ");
 196                         printf ("the FreeBSD 'des' distribution to enable");
 197                         printf (" DES encryption.\n");
 198                 }
 199         } else {
 200                 if (warn) {
 201                         printf ("DES support enabled\n");
 202                         printf ("Using %s shared object.\n", dlpath);
 203                 }
 204         }
 205
 206         return;
 207 }
 208
 209 desresp *
 210 des_crypt_1_svc(desargs *argp, struct svc_req *rqstp)
 211 {
 212         static desresp  result;
 213         struct desparams dparm;
 214
 215         if (argp->desbuf.desbuf_len > DES_MAXDATA) {
 216                 result.stat = DESERR_BADPARAM;
 217                 return(&result);
 218         }
 219
 220
 221         bcopy(argp->des_key, dparm.des_key, 8);
 222         bcopy(argp->des_ivec, dparm.des_ivec, 8);
 223         dparm.des_mode = argp->des_mode;
 224         dparm.des_dir = argp->des_dir;
 225 #ifdef BROKEN_DES
 226         dparm.UDES.UDES_buf = argp->desbuf.desbuf_val;
 227 #endif
 228
 229         /*
 230          * XXX This compensates for a bug in the libdes Secure RPC
 231          * compat interface. (Actually, there are a couple.) The
 232          * des_ecb_encrypt() routine in libdes only encrypts 8 bytes
 233          * (64 bits) at a time. However, the Sun Secure RPC ecb_crypt()
 234          * routine is supposed to be able to handle buffers up to 8Kbytes.
 235          * The rpc_enc module in libdes ignores this fact and just drops
 236          * the length parameter on the floor, encrypting only the
 237          * first 64 bits of whatever buffer you feed it. We deal with
 238          * this here: if we're using DES encryption, and we're using
 239          * ECB mode, then we make a pass over the entire buffer
 240          * ourselves. Note: the rpc_enc module incorrectly transposes
 241          * the mode flags, so when you ask for CBC mode, you're really
 242          * getting ECB mode.
 243          */
 244 #ifdef BROKEN_DES
 245         if (_my_crypt != &_arcfour_crypt && argp->des_mode == CBC) {
 246 #else
 247         if (_my_crypt != &_arcfour_crypt && argp->des_mode == ECB) {
 248 #endif
 249                 int                     i;
 250                 char                    *dptr;
 251
 252                 for (i = 0; i < argp->desbuf.desbuf_len / 8; i++) {
 253                         dptr = argp->desbuf.desbuf_val;
 254                         dptr += (i * 8);
 255 #ifdef BROKEN_DES
 256                         dparm.UDES.UDES_buf = dptr;
 257 #endif
 258                         result.stat = _my_crypt(dptr, 8, &dparm);
 259                 }
 260         } else {
 261                 result.stat = _my_crypt(argp->desbuf.desbuf_val,
 262                                         argp->desbuf.desbuf_len,
 263                                         &dparm);
 264         }
 265
 266         if (result.stat == DESERR_NONE || result.stat == DESERR_NOHWDEVICE) {
 267                 bcopy(dparm.des_ivec, result.des_ivec, 8);
 268                 result.desbuf.desbuf_len = argp->desbuf.desbuf_len;
 269                 result.desbuf.desbuf_val = argp->desbuf.desbuf_val;
 270         }
 271
 272         return (&result);
 273 }