1 /* $NetBSD: ns_sign.c,v 1.2 2022/04/19 20:32:17 rillig 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 #include <sys/cdefs.h>
20 #if 0
21 static const char rcsid[] = "Id: ns_sign.c,v 1.6 2006/03/09 23:57:56 marka Exp ";
22 #else
23 __RCSID("$NetBSD: ns_sign.c,v 1.2 2022/04/19 20:32:17 rillig Exp $");
24 #endif
25
26 /* Import. */
27
28 #include "port_before.h"
29 #include "fd_setsize.h"
30
31 #include <sys/types.h>
32 #include <sys/param.h>
33
34 #include <netinet/in.h>
35 #include <arpa/nameser.h>
36 #include <arpa/inet.h>
37
38 #include <errno.h>
39 #include <netdb.h>
40 #include <resolv.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include <time.h>
45 #include <unistd.h>
46
47 #include <isc/dst.h>
48 #include <isc/assertions.h>
49
50 #include "port_after.h"
51
52 #define BOUNDS_CHECK(ptr, count) \
53 do { \
54 if ((ptr) + (count) > eob) { \
55 errno = EMSGSIZE; \
56 return(NS_TSIG_ERROR_NO_SPACE); \
57 } \
58 } while (0)
59
60 /*%
61 * ns_sign
62 *
63 * Parameters:
64 *\li msg message to be sent
65 *\li msglen input - length of message
66 * output - length of signed message
67 *\li msgsize length of buffer containing message
68 *\li error value to put in the error field
69 *\li key tsig key used for signing
70 *\li querysig (response), the signature in the query
71 *\li querysiglen (response), the length of the signature in the query
72 *\li sig a buffer to hold the generated signature
73 *\li siglen input - length of signature buffer
74 * output - length of signature
75 *
76 * Errors:
77 *\li - bad input data (-1)
78 *\li - bad key / sign failed (-BADKEY)
79 *\li - not enough space (NS_TSIG_ERROR_NO_SPACE)
80 */
81 int
ns_sign(u_char * msg,int * msglen,int msgsize,int error,void * k,const u_char * querysig,int querysiglen,u_char * sig,int * siglen,time_t in_timesigned)82 ns_sign(u_char *msg, int *msglen, int msgsize, int error, void *k,
83 const u_char *querysig, int querysiglen, u_char *sig, int *siglen,
84 time_t in_timesigned)
85 {
86 return(ns_sign2(msg, msglen, msgsize, error, k,
87 querysig, querysiglen, sig, siglen,
88 in_timesigned, NULL, NULL));
89 }
90
91 int
ns_sign2(u_char * msg,int * msglen,int msgsize,int error,void * k,const u_char * querysig,int querysiglen,u_char * sig,int * siglen,time_t in_timesigned,u_char ** dnptrs,u_char ** lastdnptr)92 ns_sign2(u_char *msg, int *msglen, int msgsize, int error, void *k,
93 const u_char *querysig, int querysiglen, u_char *sig, int *siglen,
94 time_t in_timesigned, u_char **dnptrs, u_char **lastdnptr)
95 {
96 HEADER *hp = (void *)msg;
97 DST_KEY *key = (DST_KEY *)k;
98 u_char *cp, *eob;
99 u_char *lenp;
100 u_char *alg;
101 int n;
102 time_t timesigned;
103 u_char name[NS_MAXCDNAME];
104
105 dst_init();
106 if (msg == NULL || msglen == NULL || sig == NULL || siglen == NULL)
107 return (-1);
108
109 cp = msg + *msglen;
110 eob = msg + msgsize;
111
112 /* Name. */
113 if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) {
114 n = ns_name_pton(key->dk_key_name, name, sizeof name);
115 if (n != -1)
116 n = ns_name_pack(name, cp, (int)(eob - cp),
117 (void *)dnptrs,
118 (void *)lastdnptr);
119
120 } else {
121 n = ns_name_pton("", name, sizeof name);
122 if (n != -1)
123 n = ns_name_pack(name, cp, (int)(eob - cp), NULL, NULL);
124 }
125 if (n < 0)
126 return (NS_TSIG_ERROR_NO_SPACE);
127 cp += n;
128
129 /* Type, class, ttl, length (not filled in yet). */
130 BOUNDS_CHECK(cp, INT16SZ + INT16SZ + INT32SZ + INT16SZ);
131 PUTSHORT(ns_t_tsig, cp);
132 PUTSHORT(ns_c_any, cp);
133 PUTLONG(0, cp); /*%< TTL */
134 lenp = cp;
135 cp += 2;
136
137 /* Alg. */
138 if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) {
139 if (key->dk_alg != KEY_HMAC_MD5)
140 return (-ns_r_badkey);
141 n = dn_comp(NS_TSIG_ALG_HMAC_MD5, cp, (int)(eob - cp), NULL,
142 NULL);
143 }
144 else
145 n = dn_comp("", cp, (int)(eob - cp), NULL, NULL);
146 if (n < 0)
147 return (NS_TSIG_ERROR_NO_SPACE);
148 alg = cp;
149 cp += n;
150
151 /* Time. */
152 BOUNDS_CHECK(cp, INT16SZ + INT32SZ + INT16SZ);
153 PUTSHORT(0, cp);
154 timesigned = time(NULL);
155 if (error != ns_r_badtime)
156 PUTLONG(timesigned, cp);
157 else
158 PUTLONG(in_timesigned, cp);
159 PUTSHORT(NS_TSIG_FUDGE, cp);
160
161 /* Compute the signature. */
162 if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) {
163 void *ctx;
164 u_char buf[NS_MAXCDNAME], *cp2;
165 int nn;
166
167 dst_sign_data(SIG_MODE_INIT, key, &ctx, NULL, 0, NULL, 0);
168
169 /* Digest the query signature, if this is a response. */
170 if (querysiglen > 0 && querysig != NULL) {
171 u_int16_t len_n = htons(querysiglen);
172 dst_sign_data(SIG_MODE_UPDATE, key, &ctx,
173 (void *)&len_n, INT16SZ, NULL, 0);
174 dst_sign_data(SIG_MODE_UPDATE, key, &ctx,
175 querysig, querysiglen, NULL, 0);
176 }
177
178 /* Digest the message. */
179 dst_sign_data(SIG_MODE_UPDATE, key, &ctx, msg, *msglen,
180 NULL, 0);
181
182 /* Digest the key name. */
183 nn = ns_name_ntol(name, buf, sizeof(buf));
184 INSIST(nn > 0);
185 dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, nn, NULL, 0);
186
187 /* Digest the class and TTL. */
188 cp2 = buf;
189 PUTSHORT(ns_c_any, cp2);
190 PUTLONG(0, cp2);
191 dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, (int)(cp2 - buf),
192 NULL, 0);
193
194 /* Digest the algorithm. */
195 nn = ns_name_ntol(alg, buf, sizeof(buf));
196 INSIST(nn > 0);
197 dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, nn, NULL, 0);
198
199 /* Digest the time signed, fudge, error, and other data */
200 cp2 = buf;
201 PUTSHORT(0, cp2); /*%< Top 16 bits of time */
202 if (error != ns_r_badtime)
203 PUTLONG(timesigned, cp2);
204 else
205 PUTLONG(in_timesigned, cp2);
206 PUTSHORT(NS_TSIG_FUDGE, cp2);
207 PUTSHORT(error, cp2); /*%< Error */
208 if (error != ns_r_badtime)
209 PUTSHORT(0, cp2); /*%< Other data length */
210 else {
211 PUTSHORT(INT16SZ+INT32SZ, cp2); /*%< Other data length */
212 PUTSHORT(0, cp2); /*%< Top 16 bits of time */
213 PUTLONG(timesigned, cp2);
214 }
215 dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, (int)(cp2 - buf),
216 NULL, 0);
217
218 nn = dst_sign_data(SIG_MODE_FINAL, key, &ctx, NULL, 0,
219 sig, *siglen);
220 if (nn < 0)
221 return (-ns_r_badkey);
222 *siglen = nn;
223 } else
224 *siglen = 0;
225
226 /* Add the signature. */
227 BOUNDS_CHECK(cp, INT16SZ + (*siglen));
228 PUTSHORT(*siglen, cp);
229 memcpy(cp, sig, *siglen);
230 cp += (*siglen);
231
232 /* The original message ID & error. */
233 BOUNDS_CHECK(cp, INT16SZ + INT16SZ);
234 PUTSHORT(ntohs(hp->id), cp); /*%< already in network order */
235 PUTSHORT(error, cp);
236
237 /* Other data. */
238 BOUNDS_CHECK(cp, INT16SZ);
239 if (error != ns_r_badtime)
240 PUTSHORT(0, cp); /*%< Other data length */
241 else {
242 PUTSHORT(INT16SZ+INT32SZ, cp); /*%< Other data length */
243 BOUNDS_CHECK(cp, INT32SZ+INT16SZ);
244 PUTSHORT(0, cp); /*%< Top 16 bits of time */
245 PUTLONG(timesigned, cp);
246 }
247
248 /* Go back and fill in the length. */
249 PUTSHORT(cp - lenp - INT16SZ, lenp);
250
251 hp->arcount = htons(ntohs(hp->arcount) + 1);
252 *msglen = (int)(cp - msg);
253 return (0);
254 }
255
256 int
ns_sign_tcp_init(void * k,const u_char * querysig,int querysiglen,ns_tcp_tsig_state * state)257 ns_sign_tcp_init(void *k, const u_char *querysig, int querysiglen,
258 ns_tcp_tsig_state *state)
259 {
260 dst_init();
261 if (state == NULL || k == NULL || querysig == NULL || querysiglen < 0)
262 return (-1);
263 state->counter = -1;
264 state->key = k;
265 if (state->key->dk_alg != KEY_HMAC_MD5)
266 return (-ns_r_badkey);
267 if (querysiglen > (int)sizeof(state->sig))
268 return (-1);
269 memcpy(state->sig, querysig, querysiglen);
270 state->siglen = querysiglen;
271 return (0);
272 }
273
274 int
ns_sign_tcp(u_char * msg,int * msglen,int msgsize,int error,ns_tcp_tsig_state * state,int done)275 ns_sign_tcp(u_char *msg, int *msglen, int msgsize, int error,
276 ns_tcp_tsig_state *state, int done)
277 {
278 return (ns_sign_tcp2(msg, msglen, msgsize, error, state,
279 done, NULL, NULL));
280 }
281
282 int
ns_sign_tcp2(u_char * msg,int * msglen,int msgsize,int error,ns_tcp_tsig_state * state,int done,u_char ** dnptrs,u_char ** lastdnptr)283 ns_sign_tcp2(u_char *msg, int *msglen, int msgsize, int error,
284 ns_tcp_tsig_state *state, int done,
285 u_char **dnptrs, u_char **lastdnptr)
286 {
287 u_char *cp, *eob, *lenp;
288 u_char buf[MAXDNAME], *cp2;
289 HEADER *hp = (void *)msg;
290 time_t timesigned;
291 int n;
292
293 if (msg == NULL || msglen == NULL || state == NULL)
294 return (-1);
295
296 state->counter++;
297 if (state->counter == 0)
298 return (ns_sign2(msg, msglen, msgsize, error, state->key,
299 state->sig, state->siglen,
300 state->sig, &state->siglen, 0,
301 dnptrs, lastdnptr));
302
303 if (state->siglen > 0) {
304 u_int16_t siglen_n = htons(state->siglen);
305 dst_sign_data(SIG_MODE_INIT, state->key, &state->ctx,
306 NULL, 0, NULL, 0);
307 dst_sign_data(SIG_MODE_UPDATE, state->key, &state->ctx,
308 (void *)&siglen_n, INT16SZ, NULL, 0);
309 dst_sign_data(SIG_MODE_UPDATE, state->key, &state->ctx,
310 state->sig, state->siglen, NULL, 0);
311 state->siglen = 0;
312 }
313
314 dst_sign_data(SIG_MODE_UPDATE, state->key, &state->ctx, msg, *msglen,
315 NULL, 0);
316
317 if (done == 0 && (state->counter % 100 != 0))
318 return (0);
319
320 cp = msg + *msglen;
321 eob = msg + msgsize;
322
323 /* Name. */
324 n = dn_comp(state->key->dk_key_name, cp, (int)(eob - cp), dnptrs,
325 lastdnptr);
326 if (n < 0)
327 return (NS_TSIG_ERROR_NO_SPACE);
328 cp += n;
329
330 /* Type, class, ttl, length (not filled in yet). */
331 BOUNDS_CHECK(cp, INT16SZ + INT16SZ + INT32SZ + INT16SZ);
332 PUTSHORT(ns_t_tsig, cp);
333 PUTSHORT(ns_c_any, cp);
334 PUTLONG(0, cp); /*%< TTL */
335 lenp = cp;
336 cp += 2;
337
338 /* Alg. */
339 n = dn_comp(NS_TSIG_ALG_HMAC_MD5, cp, (int)(eob - cp), NULL, NULL);
340 if (n < 0)
341 return (NS_TSIG_ERROR_NO_SPACE);
342 cp += n;
343
344 /* Time. */
345 BOUNDS_CHECK(cp, INT16SZ + INT32SZ + INT16SZ);
346 PUTSHORT(0, cp);
347 timesigned = time(NULL);
348 PUTLONG(timesigned, cp);
349 PUTSHORT(NS_TSIG_FUDGE, cp);
350
351 /*
352 * Compute the signature.
353 */
354
355 /* Digest the time signed and fudge. */
356 cp2 = buf;
357 PUTSHORT(0, cp2); /*%< Top 16 bits of time */
358 PUTLONG(timesigned, cp2);
359 PUTSHORT(NS_TSIG_FUDGE, cp2);
360
361 dst_sign_data(SIG_MODE_UPDATE, state->key, &state->ctx,
362 buf, (int)(cp2 - buf), NULL, 0);
363
364 n = dst_sign_data(SIG_MODE_FINAL, state->key, &state->ctx, NULL, 0,
365 state->sig, (int)sizeof(state->sig));
366 if (n < 0)
367 return (-ns_r_badkey);
368 state->siglen = n;
369
370 /* Add the signature. */
371 BOUNDS_CHECK(cp, INT16SZ + state->siglen);
372 PUTSHORT(state->siglen, cp);
373 memcpy(cp, state->sig, state->siglen);
374 cp += state->siglen;
375
376 /* The original message ID & error. */
377 BOUNDS_CHECK(cp, INT16SZ + INT16SZ);
378 PUTSHORT(ntohs(hp->id), cp); /*%< already in network order */
379 PUTSHORT(error, cp);
380
381 /* Other data. */
382 BOUNDS_CHECK(cp, INT16SZ);
383 PUTSHORT(0, cp);
384
385 /* Go back and fill in the length. */
386 PUTSHORT(cp - lenp - INT16SZ, lenp);
387
388 hp->arcount = htons(ntohs(hp->arcount) + 1);
389 *msglen = (int)(cp - msg);
390 return (0);
391 }
392
393 /*! \file */
394