1 /*	$NetBSD: ns_sign.c,v 1.1.1.1 2009/04/12 15:33:51 christos Exp $	*/
2 
3 /*
4  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
5  * Copyright (c) 1999 by Internet Software Consortium, Inc.
6  *
7  * Permission to use, copy, modify, and distribute this software for any
8  * purpose with or without fee is hereby granted, provided that the above
9  * copyright notice and this permission notice appear in all copies.
10  *
11  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
12  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
14  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
17  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18  */
19 
20 #ifndef lint
21 static const char rcsid[] = "Id: ns_sign.c,v 1.6 2006/03/09 23:57:56 marka Exp";
22 #endif
23 
24 /* Import. */
25 
26 #include "port_before.h"
27 #include "fd_setsize.h"
28 
29 #include <sys/types.h>
30 #include <sys/param.h>
31 
32 #include <netinet/in.h>
33 #include <arpa/nameser.h>
34 #include <arpa/inet.h>
35 
36 #include <errno.h>
37 #include <netdb.h>
38 #include <resolv.h>
39 #include <stdio.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include <time.h>
43 #include <unistd.h>
44 
45 #include <isc/dst.h>
46 #include <isc/assertions.h>
47 
48 #include "port_after.h"
49 
50 #define BOUNDS_CHECK(ptr, count) \
51 	do { \
52 		if ((ptr) + (count) > eob) { \
53 			errno = EMSGSIZE; \
54 			return(NS_TSIG_ERROR_NO_SPACE); \
55 		} \
56 	} while (0)
57 
58 /*%
59  *  ns_sign
60  *
61  * Parameters:
62  *\li	msg		message to be sent
63  *\li	msglen		input - length of message
64  *			output - length of signed message
65  *\li	msgsize		length of buffer containing message
66  *\li	error		value to put in the error field
67  *\li	key		tsig key used for signing
68  *\li	querysig	(response), the signature in the query
69  *\li	querysiglen	(response), the length of the signature in the query
70  *\li	sig		a buffer to hold the generated signature
71  *\li	siglen		input - length of signature buffer
72  *			output - length of signature
73  *
74  * Errors:
75  *\li	- bad input data (-1)
76  *\li	- bad key / sign failed (-BADKEY)
77  *\li	- not enough space (NS_TSIG_ERROR_NO_SPACE)
78  */
79 int
80 ns_sign(u_char *msg, int *msglen, int msgsize, int error, void *k,
81 	const u_char *querysig, int querysiglen, u_char *sig, int *siglen,
82 	time_t in_timesigned)
83 {
84 	return(ns_sign2(msg, msglen, msgsize, error, k,
85 			querysig, querysiglen, sig, siglen,
86 			in_timesigned, NULL, NULL));
87 }
88 
89 int
90 ns_sign2(u_char *msg, int *msglen, int msgsize, int error, void *k,
91 	 const u_char *querysig, int querysiglen, u_char *sig, int *siglen,
92 	 time_t in_timesigned, u_char **dnptrs, u_char **lastdnptr)
93 {
94 	HEADER *hp = (HEADER *)msg;
95 	DST_KEY *key = (DST_KEY *)k;
96 	u_char *cp, *eob;
97 	u_char *lenp;
98 	u_char *alg;
99 	int n;
100 	time_t timesigned;
101         u_char name[NS_MAXCDNAME];
102 
103 	dst_init();
104 	if (msg == NULL || msglen == NULL || sig == NULL || siglen == NULL)
105 		return (-1);
106 
107 	cp = msg + *msglen;
108 	eob = msg + msgsize;
109 
110 	/* Name. */
111 	if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) {
112 		n = ns_name_pton(key->dk_key_name, name, sizeof name);
113 		if (n != -1)
114 			n = ns_name_pack(name, cp, eob - cp,
115 					 (const u_char **)dnptrs,
116 					 (const u_char **)lastdnptr);
117 
118 	} else {
119 		n = ns_name_pton("", name, sizeof name);
120 		if (n != -1)
121 			n = ns_name_pack(name, cp, eob - cp, NULL, NULL);
122 	}
123 	if (n < 0)
124 		return (NS_TSIG_ERROR_NO_SPACE);
125 	cp += n;
126 
127 	/* Type, class, ttl, length (not filled in yet). */
128 	BOUNDS_CHECK(cp, INT16SZ + INT16SZ + INT32SZ + INT16SZ);
129 	PUTSHORT(ns_t_tsig, cp);
130 	PUTSHORT(ns_c_any, cp);
131 	PUTLONG(0, cp);		/*%< TTL */
132 	lenp = cp;
133 	cp += 2;
134 
135 	/* Alg. */
136 	if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) {
137 		if (key->dk_alg != KEY_HMAC_MD5)
138 			return (-ns_r_badkey);
139 		n = dn_comp(NS_TSIG_ALG_HMAC_MD5, cp, eob - cp, NULL, NULL);
140 	}
141 	else
142 		n = dn_comp("", cp, eob - cp, NULL, NULL);
143 	if (n < 0)
144 		return (NS_TSIG_ERROR_NO_SPACE);
145 	alg = cp;
146 	cp += n;
147 
148 	/* Time. */
149 	BOUNDS_CHECK(cp, INT16SZ + INT32SZ + INT16SZ);
150 	PUTSHORT(0, cp);
151 	timesigned = time(NULL);
152 	if (error != ns_r_badtime)
153 		PUTLONG(timesigned, cp);
154 	else
155 		PUTLONG(in_timesigned, cp);
156 	PUTSHORT(NS_TSIG_FUDGE, cp);
157 
158 	/* Compute the signature. */
159 	if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) {
160 		void *ctx;
161 		u_char buf[NS_MAXCDNAME], *cp2;
162 		int n;
163 
164 		dst_sign_data(SIG_MODE_INIT, key, &ctx, NULL, 0, NULL, 0);
165 
166 		/* Digest the query signature, if this is a response. */
167 		if (querysiglen > 0 && querysig != NULL) {
168 			u_int16_t len_n = htons(querysiglen);
169 			dst_sign_data(SIG_MODE_UPDATE, key, &ctx,
170 				      (u_char *)&len_n, INT16SZ, NULL, 0);
171 			dst_sign_data(SIG_MODE_UPDATE, key, &ctx,
172 				      querysig, querysiglen, NULL, 0);
173 		}
174 
175 		/* Digest the message. */
176 		dst_sign_data(SIG_MODE_UPDATE, key, &ctx, msg, *msglen,
177 			      NULL, 0);
178 
179 		/* Digest the key name. */
180 		n = ns_name_ntol(name, buf, sizeof(buf));
181 		INSIST(n > 0);
182 		dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, n, NULL, 0);
183 
184 		/* Digest the class and TTL. */
185 		cp2 = buf;
186 		PUTSHORT(ns_c_any, cp2);
187 		PUTLONG(0, cp2);
188 		dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, cp2-buf,
189 			      NULL, 0);
190 
191 		/* Digest the algorithm. */
192 		n = ns_name_ntol(alg, buf, sizeof(buf));
193 		INSIST(n > 0);
194 		dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, n, NULL, 0);
195 
196 		/* Digest the time signed, fudge, error, and other data */
197 		cp2 = buf;
198 		PUTSHORT(0, cp2);	/*%< Top 16 bits of time */
199 		if (error != ns_r_badtime)
200 			PUTLONG(timesigned, cp2);
201 		else
202 			PUTLONG(in_timesigned, cp2);
203 		PUTSHORT(NS_TSIG_FUDGE, cp2);
204 		PUTSHORT(error, cp2);	/*%< Error */
205 		if (error != ns_r_badtime)
206 			PUTSHORT(0, cp2);	/*%< Other data length */
207 		else {
208 			PUTSHORT(INT16SZ+INT32SZ, cp2);	/*%< Other data length */
209 			PUTSHORT(0, cp2);	/*%< Top 16 bits of time */
210 			PUTLONG(timesigned, cp2);
211 		}
212 		dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, cp2-buf,
213 			      NULL, 0);
214 
215 		n = dst_sign_data(SIG_MODE_FINAL, key, &ctx, NULL, 0,
216 				  sig, *siglen);
217 		if (n < 0)
218 			return (-ns_r_badkey);
219 		*siglen = n;
220 	} else
221 		*siglen = 0;
222 
223 	/* Add the signature. */
224 	BOUNDS_CHECK(cp, INT16SZ + (*siglen));
225 	PUTSHORT(*siglen, cp);
226 	memcpy(cp, sig, *siglen);
227 	cp += (*siglen);
228 
229 	/* The original message ID & error. */
230 	BOUNDS_CHECK(cp, INT16SZ + INT16SZ);
231 	PUTSHORT(ntohs(hp->id), cp);	/*%< already in network order */
232 	PUTSHORT(error, cp);
233 
234 	/* Other data. */
235 	BOUNDS_CHECK(cp, INT16SZ);
236 	if (error != ns_r_badtime)
237 		PUTSHORT(0, cp);	/*%< Other data length */
238 	else {
239 		PUTSHORT(INT16SZ+INT32SZ, cp);	/*%< Other data length */
240 		BOUNDS_CHECK(cp, INT32SZ+INT16SZ);
241 		PUTSHORT(0, cp);	/*%< Top 16 bits of time */
242 		PUTLONG(timesigned, cp);
243 	}
244 
245 	/* Go back and fill in the length. */
246 	PUTSHORT(cp - lenp - INT16SZ, lenp);
247 
248 	hp->arcount = htons(ntohs(hp->arcount) + 1);
249 	*msglen = (cp - msg);
250 	return (0);
251 }
252 
253 int
254 ns_sign_tcp_init(void *k, const u_char *querysig, int querysiglen,
255 		 ns_tcp_tsig_state *state)
256 {
257 	dst_init();
258 	if (state == NULL || k == NULL || querysig == NULL || querysiglen < 0)
259 		return (-1);
260 	state->counter = -1;
261 	state->key = k;
262 	if (state->key->dk_alg != KEY_HMAC_MD5)
263 		return (-ns_r_badkey);
264 	if (querysiglen > (int)sizeof(state->sig))
265 		return (-1);
266 	memcpy(state->sig, querysig, querysiglen);
267 	state->siglen = querysiglen;
268 	return (0);
269 }
270 
271 int
272 ns_sign_tcp(u_char *msg, int *msglen, int msgsize, int error,
273 	    ns_tcp_tsig_state *state, int done)
274 {
275 	return (ns_sign_tcp2(msg, msglen, msgsize, error, state,
276 			     done, NULL, NULL));
277 }
278 
279 int
280 ns_sign_tcp2(u_char *msg, int *msglen, int msgsize, int error,
281 	     ns_tcp_tsig_state *state, int done,
282 	     u_char **dnptrs, u_char **lastdnptr)
283 {
284 	u_char *cp, *eob, *lenp;
285 	u_char buf[MAXDNAME], *cp2;
286 	HEADER *hp = (HEADER *)msg;
287 	time_t timesigned;
288 	int n;
289 
290 	if (msg == NULL || msglen == NULL || state == NULL)
291 		return (-1);
292 
293 	state->counter++;
294 	if (state->counter == 0)
295 		return (ns_sign2(msg, msglen, msgsize, error, state->key,
296 				 state->sig, state->siglen,
297 				 state->sig, &state->siglen, 0,
298 				 dnptrs, lastdnptr));
299 
300 	if (state->siglen > 0) {
301 		u_int16_t siglen_n = htons(state->siglen);
302 		dst_sign_data(SIG_MODE_INIT, state->key, &state->ctx,
303 			      NULL, 0, NULL, 0);
304 		dst_sign_data(SIG_MODE_UPDATE, state->key, &state->ctx,
305 			      (u_char *)&siglen_n, INT16SZ, NULL, 0);
306 		dst_sign_data(SIG_MODE_UPDATE, state->key, &state->ctx,
307 			      state->sig, state->siglen, NULL, 0);
308 		state->siglen = 0;
309 	}
310 
311 	dst_sign_data(SIG_MODE_UPDATE, state->key, &state->ctx, msg, *msglen,
312 		      NULL, 0);
313 
314 	if (done == 0 && (state->counter % 100 != 0))
315 		return (0);
316 
317 	cp = msg + *msglen;
318 	eob = msg + msgsize;
319 
320 	/* Name. */
321 	n = dn_comp(state->key->dk_key_name, cp, eob - cp, dnptrs, lastdnptr);
322 	if (n < 0)
323 		return (NS_TSIG_ERROR_NO_SPACE);
324 	cp += n;
325 
326 	/* Type, class, ttl, length (not filled in yet). */
327 	BOUNDS_CHECK(cp, INT16SZ + INT16SZ + INT32SZ + INT16SZ);
328 	PUTSHORT(ns_t_tsig, cp);
329 	PUTSHORT(ns_c_any, cp);
330 	PUTLONG(0, cp);		/*%< TTL */
331 	lenp = cp;
332 	cp += 2;
333 
334 	/* Alg. */
335 	n = dn_comp(NS_TSIG_ALG_HMAC_MD5, cp, eob - cp, NULL, NULL);
336 	if (n < 0)
337 		return (NS_TSIG_ERROR_NO_SPACE);
338 	cp += n;
339 
340 	/* Time. */
341 	BOUNDS_CHECK(cp, INT16SZ + INT32SZ + INT16SZ);
342 	PUTSHORT(0, cp);
343 	timesigned = time(NULL);
344 	PUTLONG(timesigned, cp);
345 	PUTSHORT(NS_TSIG_FUDGE, cp);
346 
347 	/*
348 	 * Compute the signature.
349 	 */
350 
351 	/* Digest the time signed and fudge. */
352 	cp2 = buf;
353 	PUTSHORT(0, cp2);	/*%< Top 16 bits of time */
354 	PUTLONG(timesigned, cp2);
355 	PUTSHORT(NS_TSIG_FUDGE, cp2);
356 
357 	dst_sign_data(SIG_MODE_UPDATE, state->key, &state->ctx,
358 		      buf, cp2 - buf, NULL, 0);
359 
360 	n = dst_sign_data(SIG_MODE_FINAL, state->key, &state->ctx, NULL, 0,
361 			  state->sig, sizeof(state->sig));
362 	if (n < 0)
363 		return (-ns_r_badkey);
364 	state->siglen = n;
365 
366 	/* Add the signature. */
367 	BOUNDS_CHECK(cp, INT16SZ + state->siglen);
368 	PUTSHORT(state->siglen, cp);
369 	memcpy(cp, state->sig, state->siglen);
370 	cp += state->siglen;
371 
372 	/* The original message ID & error. */
373 	BOUNDS_CHECK(cp, INT16SZ + INT16SZ);
374 	PUTSHORT(ntohs(hp->id), cp);	/*%< already in network order */
375 	PUTSHORT(error, cp);
376 
377 	/* Other data. */
378 	BOUNDS_CHECK(cp, INT16SZ);
379 	PUTSHORT(0, cp);
380 
381 	/* Go back and fill in the length. */
382 	PUTSHORT(cp - lenp - INT16SZ, lenp);
383 
384 	hp->arcount = htons(ntohs(hp->arcount) + 1);
385 	*msglen = (cp - msg);
386 	return (0);
387 }
388 
389 /*! \file */
390