xref: /dragonfly/usr.sbin/keyserv/crypt_server.c (revision 0ac6bf9d) 
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 }
274