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 == CBC_DES) ? CBC : ECB; 227 dparm.des_dir = (argp->des_dir == ENCRYPT_DES) ? ENCRYPT : DECRYPT; 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 } 277