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2b442ac8 LP |
1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ |
2 | ||
3 | /*** | |
4 | This file is part of systemd. | |
5 | ||
6 | Copyright 2015 Lennart Poettering | |
7 | ||
8 | systemd is free software; you can redistribute it and/or modify it | |
9 | under the terms of the GNU Lesser General Public License as published by | |
10 | the Free Software Foundation; either version 2.1 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | systemd is distributed in the hope that it will be useful, but | |
14 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | Lesser General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU Lesser General Public License | |
19 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
20 | ***/ | |
21 | ||
22 | #include <gcrypt.h> | |
23 | ||
24 | #include "alloc-util.h" | |
25 | #include "dns-domain.h" | |
26 | #include "resolved-dns-dnssec.h" | |
27 | #include "resolved-dns-packet.h" | |
24710c48 | 28 | #include "string-table.h" |
2b442ac8 LP |
29 | |
30 | /* Open question: | |
31 | * | |
32 | * How does the DNSSEC canonical form of a hostname with a label | |
33 | * containing a dot look like, the way DNS-SD does it? | |
34 | * | |
2cd87277 LP |
35 | * TODO: |
36 | * | |
37 | * - Iterative validation | |
38 | * - NSEC proof of non-existance | |
39 | * - NSEC3 proof of non-existance | |
bb1fa242 LP |
40 | * - Make trust anchor store read additional DS+DNSKEY data from disk |
41 | * - wildcard zones compatibility | |
42 | * - multi-label zone compatibility | |
d12bf2bd | 43 | * - DNSSEC cname/dname compatibility |
bb1fa242 | 44 | * - per-interface DNSSEC setting |
2cd87277 LP |
45 | * - DSA support |
46 | * - EC support? | |
47 | * | |
2b442ac8 LP |
48 | * */ |
49 | ||
50 | #define VERIFY_RRS_MAX 256 | |
51 | #define MAX_KEY_SIZE (32*1024) | |
52 | ||
896c5672 LP |
53 | /* Permit a maximum clock skew of 1h 10min. This should be enough to deal with DST confusion */ |
54 | #define SKEW_MAX (1*USEC_PER_HOUR + 10*USEC_PER_MINUTE) | |
55 | ||
2b442ac8 LP |
56 | /* |
57 | * The DNSSEC Chain of trust: | |
58 | * | |
59 | * Normal RRs are protected via RRSIG RRs in combination with DNSKEY RRs, all in the same zone | |
60 | * DNSKEY RRs are either protected like normal RRs, or via a DS from a zone "higher" up the tree | |
61 | * DS RRs are protected like normal RRs | |
62 | * | |
63 | * Example chain: | |
64 | * Normal RR → RRSIG/DNSKEY+ → DS → RRSIG/DNSKEY+ → DS → ... → DS → RRSIG/DNSKEY+ → DS | |
65 | */ | |
66 | ||
67 | static bool dnssec_algorithm_supported(int algorithm) { | |
964ef14c LP |
68 | return IN_SET(algorithm, |
69 | DNSSEC_ALGORITHM_RSASHA1, | |
70 | DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1, | |
71 | DNSSEC_ALGORITHM_RSASHA256, | |
72 | DNSSEC_ALGORITHM_RSASHA512); | |
2b442ac8 LP |
73 | } |
74 | ||
75 | static bool dnssec_digest_supported(int digest) { | |
964ef14c LP |
76 | return IN_SET(digest, |
77 | DNSSEC_DIGEST_SHA1, | |
78 | DNSSEC_DIGEST_SHA256); | |
2b442ac8 LP |
79 | } |
80 | ||
81 | uint16_t dnssec_keytag(DnsResourceRecord *dnskey) { | |
82 | const uint8_t *p; | |
83 | uint32_t sum; | |
84 | size_t i; | |
85 | ||
86 | /* The algorithm from RFC 4034, Appendix B. */ | |
87 | ||
88 | assert(dnskey); | |
89 | assert(dnskey->key->type == DNS_TYPE_DNSKEY); | |
90 | ||
91 | sum = (uint32_t) dnskey->dnskey.flags + | |
92 | ((((uint32_t) dnskey->dnskey.protocol) << 8) + (uint32_t) dnskey->dnskey.algorithm); | |
93 | ||
94 | p = dnskey->dnskey.key; | |
95 | ||
96 | for (i = 0; i < dnskey->dnskey.key_size; i++) | |
97 | sum += (i & 1) == 0 ? (uint32_t) p[i] << 8 : (uint32_t) p[i]; | |
98 | ||
99 | sum += (sum >> 16) & UINT32_C(0xFFFF); | |
100 | ||
101 | return sum & UINT32_C(0xFFFF); | |
102 | } | |
103 | ||
104 | static int rr_compare(const void *a, const void *b) { | |
105 | DnsResourceRecord **x = (DnsResourceRecord**) a, **y = (DnsResourceRecord**) b; | |
106 | size_t m; | |
107 | int r; | |
108 | ||
109 | /* Let's order the RRs according to RFC 4034, Section 6.3 */ | |
110 | ||
111 | assert(x); | |
112 | assert(*x); | |
113 | assert((*x)->wire_format); | |
114 | assert(y); | |
115 | assert(*y); | |
116 | assert((*y)->wire_format); | |
117 | ||
118 | m = MIN((*x)->wire_format_size, (*y)->wire_format_size); | |
119 | ||
120 | r = memcmp((*x)->wire_format, (*y)->wire_format, m); | |
121 | if (r != 0) | |
122 | return r; | |
123 | ||
124 | if ((*x)->wire_format_size < (*y)->wire_format_size) | |
125 | return -1; | |
126 | else if ((*x)->wire_format_size > (*y)->wire_format_size) | |
127 | return 1; | |
128 | ||
129 | return 0; | |
130 | } | |
131 | ||
132 | static int dnssec_rsa_verify( | |
133 | const char *hash_algorithm, | |
134 | const void *signature, size_t signature_size, | |
135 | const void *data, size_t data_size, | |
136 | const void *exponent, size_t exponent_size, | |
137 | const void *modulus, size_t modulus_size) { | |
138 | ||
139 | gcry_sexp_t public_key_sexp = NULL, data_sexp = NULL, signature_sexp = NULL; | |
140 | gcry_mpi_t n = NULL, e = NULL, s = NULL; | |
141 | gcry_error_t ge; | |
142 | int r; | |
143 | ||
144 | assert(hash_algorithm); | |
145 | ||
146 | ge = gcry_mpi_scan(&s, GCRYMPI_FMT_USG, signature, signature_size, NULL); | |
147 | if (ge != 0) { | |
148 | r = -EIO; | |
149 | goto finish; | |
150 | } | |
151 | ||
152 | ge = gcry_mpi_scan(&e, GCRYMPI_FMT_USG, exponent, exponent_size, NULL); | |
153 | if (ge != 0) { | |
154 | r = -EIO; | |
155 | goto finish; | |
156 | } | |
157 | ||
158 | ge = gcry_mpi_scan(&n, GCRYMPI_FMT_USG, modulus, modulus_size, NULL); | |
159 | if (ge != 0) { | |
160 | r = -EIO; | |
161 | goto finish; | |
162 | } | |
163 | ||
164 | ge = gcry_sexp_build(&signature_sexp, | |
165 | NULL, | |
166 | "(sig-val (rsa (s %m)))", | |
167 | s); | |
168 | ||
169 | if (ge != 0) { | |
170 | r = -EIO; | |
171 | goto finish; | |
172 | } | |
173 | ||
174 | ge = gcry_sexp_build(&data_sexp, | |
175 | NULL, | |
176 | "(data (flags pkcs1) (hash %s %b))", | |
177 | hash_algorithm, | |
178 | (int) data_size, | |
179 | data); | |
180 | if (ge != 0) { | |
181 | r = -EIO; | |
182 | goto finish; | |
183 | } | |
184 | ||
185 | ge = gcry_sexp_build(&public_key_sexp, | |
186 | NULL, | |
187 | "(public-key (rsa (n %m) (e %m)))", | |
188 | n, | |
189 | e); | |
190 | if (ge != 0) { | |
191 | r = -EIO; | |
192 | goto finish; | |
193 | } | |
194 | ||
195 | ge = gcry_pk_verify(signature_sexp, data_sexp, public_key_sexp); | |
d12bf2bd | 196 | if (gpg_err_code(ge) == GPG_ERR_BAD_SIGNATURE) |
2b442ac8 | 197 | r = 0; |
d12bf2bd LP |
198 | else if (ge != 0) { |
199 | log_debug("RSA signature check failed: %s", gpg_strerror(ge)); | |
2b442ac8 | 200 | r = -EIO; |
d12bf2bd | 201 | } else |
2b442ac8 LP |
202 | r = 1; |
203 | ||
204 | finish: | |
205 | if (e) | |
206 | gcry_mpi_release(e); | |
207 | if (n) | |
208 | gcry_mpi_release(n); | |
209 | if (s) | |
210 | gcry_mpi_release(s); | |
211 | ||
212 | if (public_key_sexp) | |
213 | gcry_sexp_release(public_key_sexp); | |
214 | if (signature_sexp) | |
215 | gcry_sexp_release(signature_sexp); | |
216 | if (data_sexp) | |
217 | gcry_sexp_release(data_sexp); | |
218 | ||
219 | return r; | |
220 | } | |
221 | ||
222 | static void md_add_uint8(gcry_md_hd_t md, uint8_t v) { | |
223 | gcry_md_write(md, &v, sizeof(v)); | |
224 | } | |
225 | ||
226 | static void md_add_uint16(gcry_md_hd_t md, uint16_t v) { | |
227 | v = htobe16(v); | |
228 | gcry_md_write(md, &v, sizeof(v)); | |
229 | } | |
230 | ||
231 | static void md_add_uint32(gcry_md_hd_t md, uint32_t v) { | |
232 | v = htobe32(v); | |
233 | gcry_md_write(md, &v, sizeof(v)); | |
234 | } | |
235 | ||
2a326321 LP |
236 | static int dnssec_rrsig_expired(DnsResourceRecord *rrsig, usec_t realtime) { |
237 | usec_t expiration, inception, skew; | |
238 | ||
239 | assert(rrsig); | |
240 | assert(rrsig->key->type == DNS_TYPE_RRSIG); | |
241 | ||
242 | if (realtime == USEC_INFINITY) | |
243 | realtime = now(CLOCK_REALTIME); | |
244 | ||
245 | expiration = rrsig->rrsig.expiration * USEC_PER_SEC; | |
246 | inception = rrsig->rrsig.inception * USEC_PER_SEC; | |
247 | ||
248 | if (inception > expiration) | |
2a44bec4 | 249 | return -EKEYREJECTED; |
2a326321 | 250 | |
896c5672 LP |
251 | /* Permit a certain amount of clock skew of 10% of the valid |
252 | * time range. This takes inspiration from unbound's | |
253 | * resolver. */ | |
2a326321 | 254 | skew = (expiration - inception) / 10; |
896c5672 LP |
255 | if (skew > SKEW_MAX) |
256 | skew = SKEW_MAX; | |
2a326321 LP |
257 | |
258 | if (inception < skew) | |
259 | inception = 0; | |
260 | else | |
261 | inception -= skew; | |
262 | ||
263 | if (expiration + skew < expiration) | |
264 | expiration = USEC_INFINITY; | |
265 | else | |
266 | expiration += skew; | |
267 | ||
268 | return realtime < inception || realtime > expiration; | |
269 | } | |
270 | ||
271 | int dnssec_verify_rrset( | |
272 | DnsAnswer *a, | |
273 | DnsResourceKey *key, | |
274 | DnsResourceRecord *rrsig, | |
275 | DnsResourceRecord *dnskey, | |
547973de LP |
276 | usec_t realtime, |
277 | DnssecResult *result) { | |
2a326321 | 278 | |
2b442ac8 LP |
279 | uint8_t wire_format_name[DNS_WIRE_FOMAT_HOSTNAME_MAX]; |
280 | size_t exponent_size, modulus_size, hash_size; | |
281 | void *exponent, *modulus, *hash; | |
282 | DnsResourceRecord **list, *rr; | |
283 | gcry_md_hd_t md = NULL; | |
284 | size_t k, n = 0; | |
285 | int r; | |
286 | ||
287 | assert(key); | |
288 | assert(rrsig); | |
289 | assert(dnskey); | |
547973de | 290 | assert(result); |
2a326321 LP |
291 | assert(rrsig->key->type == DNS_TYPE_RRSIG); |
292 | assert(dnskey->key->type == DNS_TYPE_DNSKEY); | |
2b442ac8 LP |
293 | |
294 | /* Verifies the the RRSet matching the specified "key" in "a", | |
295 | * using the signature "rrsig" and the key "dnskey". It's | |
296 | * assumed the RRSIG and DNSKEY match. */ | |
297 | ||
298 | if (!dnssec_algorithm_supported(rrsig->rrsig.algorithm)) | |
299 | return -EOPNOTSUPP; | |
300 | ||
301 | if (a->n_rrs > VERIFY_RRS_MAX) | |
302 | return -E2BIG; | |
303 | ||
2a326321 LP |
304 | r = dnssec_rrsig_expired(rrsig, realtime); |
305 | if (r < 0) | |
306 | return r; | |
547973de LP |
307 | if (r > 0) { |
308 | *result = DNSSEC_SIGNATURE_EXPIRED; | |
309 | return 0; | |
310 | } | |
2a326321 | 311 | |
2b442ac8 LP |
312 | /* Collect all relevant RRs in a single array, so that we can look at the RRset */ |
313 | list = newa(DnsResourceRecord *, a->n_rrs); | |
314 | ||
315 | DNS_ANSWER_FOREACH(rr, a) { | |
316 | r = dns_resource_key_equal(key, rr->key); | |
317 | if (r < 0) | |
318 | return r; | |
319 | if (r == 0) | |
320 | continue; | |
321 | ||
322 | /* We need the wire format for ordering, and digest calculation */ | |
323 | r = dns_resource_record_to_wire_format(rr, true); | |
324 | if (r < 0) | |
325 | return r; | |
326 | ||
327 | list[n++] = rr; | |
328 | } | |
329 | ||
330 | if (n <= 0) | |
331 | return -ENODATA; | |
332 | ||
333 | /* Bring the RRs into canonical order */ | |
6c5e8fbf | 334 | qsort_safe(list, n, sizeof(DnsResourceRecord*), rr_compare); |
2b442ac8 LP |
335 | |
336 | /* OK, the RRs are now in canonical order. Let's calculate the digest */ | |
337 | switch (rrsig->rrsig.algorithm) { | |
338 | ||
339 | case DNSSEC_ALGORITHM_RSASHA1: | |
964ef14c | 340 | case DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1: |
2b442ac8 LP |
341 | gcry_md_open(&md, GCRY_MD_SHA1, 0); |
342 | hash_size = 20; | |
343 | break; | |
344 | ||
345 | case DNSSEC_ALGORITHM_RSASHA256: | |
346 | gcry_md_open(&md, GCRY_MD_SHA256, 0); | |
347 | hash_size = 32; | |
348 | break; | |
349 | ||
350 | case DNSSEC_ALGORITHM_RSASHA512: | |
351 | gcry_md_open(&md, GCRY_MD_SHA512, 0); | |
352 | hash_size = 64; | |
353 | break; | |
354 | ||
355 | default: | |
356 | assert_not_reached("Unknown digest"); | |
357 | } | |
358 | ||
359 | if (!md) | |
360 | return -EIO; | |
361 | ||
362 | md_add_uint16(md, rrsig->rrsig.type_covered); | |
363 | md_add_uint8(md, rrsig->rrsig.algorithm); | |
364 | md_add_uint8(md, rrsig->rrsig.labels); | |
365 | md_add_uint32(md, rrsig->rrsig.original_ttl); | |
366 | md_add_uint32(md, rrsig->rrsig.expiration); | |
367 | md_add_uint32(md, rrsig->rrsig.inception); | |
368 | md_add_uint16(md, rrsig->rrsig.key_tag); | |
369 | ||
370 | r = dns_name_to_wire_format(rrsig->rrsig.signer, wire_format_name, sizeof(wire_format_name), true); | |
371 | if (r < 0) | |
372 | goto finish; | |
373 | gcry_md_write(md, wire_format_name, r); | |
374 | ||
375 | for (k = 0; k < n; k++) { | |
376 | size_t l; | |
377 | rr = list[k]; | |
378 | ||
379 | r = dns_name_to_wire_format(DNS_RESOURCE_KEY_NAME(rr->key), wire_format_name, sizeof(wire_format_name), true); | |
380 | if (r < 0) | |
381 | goto finish; | |
382 | gcry_md_write(md, wire_format_name, r); | |
383 | ||
384 | md_add_uint16(md, rr->key->type); | |
385 | md_add_uint16(md, rr->key->class); | |
386 | md_add_uint32(md, rrsig->rrsig.original_ttl); | |
387 | ||
388 | assert(rr->wire_format_rdata_offset <= rr->wire_format_size); | |
389 | l = rr->wire_format_size - rr->wire_format_rdata_offset; | |
390 | assert(l <= 0xFFFF); | |
391 | ||
392 | md_add_uint16(md, (uint16_t) l); | |
393 | gcry_md_write(md, (uint8_t*) rr->wire_format + rr->wire_format_rdata_offset, l); | |
394 | } | |
395 | ||
396 | hash = gcry_md_read(md, 0); | |
397 | if (!hash) { | |
398 | r = -EIO; | |
399 | goto finish; | |
400 | } | |
401 | ||
402 | if (*(uint8_t*) dnskey->dnskey.key == 0) { | |
403 | /* exponent is > 255 bytes long */ | |
404 | ||
405 | exponent = (uint8_t*) dnskey->dnskey.key + 3; | |
406 | exponent_size = | |
407 | ((size_t) (((uint8_t*) dnskey->dnskey.key)[0]) << 8) | | |
408 | ((size_t) ((uint8_t*) dnskey->dnskey.key)[1]); | |
409 | ||
410 | if (exponent_size < 256) { | |
411 | r = -EINVAL; | |
412 | goto finish; | |
413 | } | |
414 | ||
415 | if (3 + exponent_size >= dnskey->dnskey.key_size) { | |
416 | r = -EINVAL; | |
417 | goto finish; | |
418 | } | |
419 | ||
420 | modulus = (uint8_t*) dnskey->dnskey.key + 3 + exponent_size; | |
421 | modulus_size = dnskey->dnskey.key_size - 3 - exponent_size; | |
422 | ||
423 | } else { | |
424 | /* exponent is <= 255 bytes long */ | |
425 | ||
426 | exponent = (uint8_t*) dnskey->dnskey.key + 1; | |
427 | exponent_size = (size_t) ((uint8_t*) dnskey->dnskey.key)[0]; | |
428 | ||
429 | if (exponent_size <= 0) { | |
430 | r = -EINVAL; | |
431 | goto finish; | |
432 | } | |
433 | ||
434 | if (1 + exponent_size >= dnskey->dnskey.key_size) { | |
435 | r = -EINVAL; | |
436 | goto finish; | |
437 | } | |
438 | ||
439 | modulus = (uint8_t*) dnskey->dnskey.key + 1 + exponent_size; | |
440 | modulus_size = dnskey->dnskey.key_size - 1 - exponent_size; | |
441 | } | |
442 | ||
443 | r = dnssec_rsa_verify( | |
444 | gcry_md_algo_name(gcry_md_get_algo(md)), | |
445 | rrsig->rrsig.signature, rrsig->rrsig.signature_size, | |
446 | hash, hash_size, | |
447 | exponent, exponent_size, | |
448 | modulus, modulus_size); | |
449 | if (r < 0) | |
450 | goto finish; | |
451 | ||
547973de LP |
452 | *result = r ? DNSSEC_VALIDATED : DNSSEC_INVALID; |
453 | r = 0; | |
2b442ac8 LP |
454 | |
455 | finish: | |
456 | gcry_md_close(md); | |
457 | return r; | |
458 | } | |
459 | ||
460 | int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnskey) { | |
461 | ||
462 | assert(rrsig); | |
463 | assert(dnskey); | |
464 | ||
465 | /* Checks if the specified DNSKEY RR matches the key used for | |
466 | * the signature in the specified RRSIG RR */ | |
467 | ||
468 | if (rrsig->key->type != DNS_TYPE_RRSIG) | |
469 | return -EINVAL; | |
470 | ||
471 | if (dnskey->key->type != DNS_TYPE_DNSKEY) | |
472 | return 0; | |
473 | if (dnskey->key->class != rrsig->key->class) | |
474 | return 0; | |
475 | if ((dnskey->dnskey.flags & DNSKEY_FLAG_ZONE_KEY) == 0) | |
476 | return 0; | |
477 | if (dnskey->dnskey.protocol != 3) | |
478 | return 0; | |
479 | if (dnskey->dnskey.algorithm != rrsig->rrsig.algorithm) | |
480 | return 0; | |
481 | ||
482 | if (dnssec_keytag(dnskey) != rrsig->rrsig.key_tag) | |
483 | return 0; | |
484 | ||
15accc27 | 485 | return dns_name_equal(DNS_RESOURCE_KEY_NAME(dnskey->key), rrsig->rrsig.signer); |
2b442ac8 LP |
486 | } |
487 | ||
488 | int dnssec_key_match_rrsig(DnsResourceKey *key, DnsResourceRecord *rrsig) { | |
489 | assert(key); | |
490 | assert(rrsig); | |
491 | ||
492 | /* Checks if the specified RRSIG RR protects the RRSet of the specified RR key. */ | |
493 | ||
494 | if (rrsig->key->type != DNS_TYPE_RRSIG) | |
495 | return 0; | |
496 | if (rrsig->key->class != key->class) | |
497 | return 0; | |
498 | if (rrsig->rrsig.type_covered != key->type) | |
499 | return 0; | |
500 | ||
501 | return dns_name_equal(DNS_RESOURCE_KEY_NAME(rrsig->key), DNS_RESOURCE_KEY_NAME(key)); | |
502 | } | |
503 | ||
2a326321 LP |
504 | int dnssec_verify_rrset_search( |
505 | DnsAnswer *a, | |
506 | DnsResourceKey *key, | |
507 | DnsAnswer *validated_dnskeys, | |
547973de LP |
508 | usec_t realtime, |
509 | DnssecResult *result) { | |
2a326321 | 510 | |
2b442ac8 LP |
511 | bool found_rrsig = false, found_dnskey = false; |
512 | DnsResourceRecord *rrsig; | |
513 | int r; | |
514 | ||
515 | assert(key); | |
547973de | 516 | assert(result); |
2b442ac8 | 517 | |
15accc27 | 518 | /* Verifies all RRs from "a" that match the key "key", against DNSKEY and DS RRs in "validated_dnskeys" */ |
2b442ac8 LP |
519 | |
520 | if (!a || a->n_rrs <= 0) | |
521 | return -ENODATA; | |
522 | ||
523 | /* Iterate through each RRSIG RR. */ | |
524 | DNS_ANSWER_FOREACH(rrsig, a) { | |
525 | DnsResourceRecord *dnskey; | |
526 | ||
527 | r = dnssec_key_match_rrsig(key, rrsig); | |
528 | if (r < 0) | |
529 | return r; | |
530 | if (r == 0) | |
531 | continue; | |
532 | ||
533 | found_rrsig = true; | |
534 | ||
547973de | 535 | /* Look for a matching key */ |
2b442ac8 | 536 | DNS_ANSWER_FOREACH(dnskey, validated_dnskeys) { |
547973de | 537 | DnssecResult one_result; |
2b442ac8 LP |
538 | |
539 | r = dnssec_rrsig_match_dnskey(rrsig, dnskey); | |
540 | if (r < 0) | |
541 | return r; | |
542 | if (r == 0) | |
543 | continue; | |
544 | ||
545 | found_dnskey = true; | |
546 | ||
2a326321 LP |
547 | /* Take the time here, if it isn't set yet, so |
548 | * that we do all validations with the same | |
549 | * time. */ | |
550 | if (realtime == USEC_INFINITY) | |
551 | realtime = now(CLOCK_REALTIME); | |
552 | ||
2b442ac8 LP |
553 | /* Yay, we found a matching RRSIG with a matching |
554 | * DNSKEY, awesome. Now let's verify all entries of | |
555 | * the RRSet against the RRSIG and DNSKEY | |
556 | * combination. */ | |
557 | ||
547973de | 558 | r = dnssec_verify_rrset(a, key, rrsig, dnskey, realtime, &one_result); |
2b442ac8 LP |
559 | if (r < 0 && r != EOPNOTSUPP) |
560 | return r; | |
547973de LP |
561 | if (one_result == DNSSEC_VALIDATED) { |
562 | *result = DNSSEC_VALIDATED; | |
563 | return 0; | |
564 | } | |
2b442ac8 LP |
565 | |
566 | /* If the signature is invalid, or done using | |
567 | an unsupported algorithm, let's try another | |
568 | key and/or signature. After all they | |
569 | key_tags and stuff are not unique, and | |
570 | might be shared by multiple keys. */ | |
571 | } | |
572 | } | |
573 | ||
574 | if (found_dnskey) | |
547973de LP |
575 | *result = DNSSEC_INVALID; |
576 | else if (found_rrsig) | |
577 | *result = DNSSEC_MISSING_KEY; | |
578 | else | |
579 | *result = DNSSEC_NO_SIGNATURE; | |
2b442ac8 | 580 | |
547973de | 581 | return 0; |
2b442ac8 LP |
582 | } |
583 | ||
584 | int dnssec_canonicalize(const char *n, char *buffer, size_t buffer_max) { | |
2b442ac8 LP |
585 | size_t c = 0; |
586 | int r; | |
587 | ||
588 | /* Converts the specified hostname into DNSSEC canonicalized | |
589 | * form. */ | |
590 | ||
591 | if (buffer_max < 2) | |
592 | return -ENOBUFS; | |
593 | ||
594 | for (;;) { | |
595 | size_t i; | |
596 | ||
597 | r = dns_label_unescape(&n, buffer, buffer_max); | |
598 | if (r < 0) | |
599 | return r; | |
600 | if (r == 0) | |
601 | break; | |
602 | if (r > 0) { | |
603 | int k; | |
604 | ||
605 | /* DNSSEC validation is always done on the ASCII version of the label */ | |
606 | k = dns_label_apply_idna(buffer, r, buffer, buffer_max); | |
607 | if (k < 0) | |
608 | return k; | |
609 | if (k > 0) | |
610 | r = k; | |
611 | } | |
612 | ||
613 | if (buffer_max < (size_t) r + 2) | |
614 | return -ENOBUFS; | |
615 | ||
616 | /* The DNSSEC canonical form is not clear on what to | |
617 | * do with dots appearing in labels, the way DNS-SD | |
618 | * does it. Refuse it for now. */ | |
619 | ||
620 | if (memchr(buffer, '.', r)) | |
621 | return -EINVAL; | |
622 | ||
623 | for (i = 0; i < (size_t) r; i ++) { | |
624 | if (buffer[i] >= 'A' && buffer[i] <= 'Z') | |
625 | buffer[i] = buffer[i] - 'A' + 'a'; | |
626 | } | |
627 | ||
628 | buffer[r] = '.'; | |
629 | ||
630 | buffer += r + 1; | |
631 | c += r + 1; | |
632 | ||
633 | buffer_max -= r + 1; | |
634 | } | |
635 | ||
636 | if (c <= 0) { | |
637 | /* Not even a single label: this is the root domain name */ | |
638 | ||
639 | assert(buffer_max > 2); | |
640 | buffer[0] = '.'; | |
641 | buffer[1] = 0; | |
642 | ||
643 | return 1; | |
644 | } | |
645 | ||
646 | return (int) c; | |
647 | } | |
648 | ||
649 | int dnssec_verify_dnskey(DnsResourceRecord *dnskey, DnsResourceRecord *ds) { | |
650 | gcry_md_hd_t md = NULL; | |
651 | char owner_name[DNSSEC_CANONICAL_HOSTNAME_MAX]; | |
652 | void *result; | |
653 | int r; | |
654 | ||
655 | assert(dnskey); | |
656 | assert(ds); | |
657 | ||
658 | /* Implements DNSKEY verification by a DS, according to RFC 4035, section 5.2 */ | |
659 | ||
660 | if (dnskey->key->type != DNS_TYPE_DNSKEY) | |
661 | return -EINVAL; | |
662 | if (ds->key->type != DNS_TYPE_DS) | |
663 | return -EINVAL; | |
664 | if ((dnskey->dnskey.flags & DNSKEY_FLAG_ZONE_KEY) == 0) | |
665 | return -EKEYREJECTED; | |
666 | if (dnskey->dnskey.protocol != 3) | |
667 | return -EKEYREJECTED; | |
668 | ||
2b442ac8 LP |
669 | if (dnskey->dnskey.algorithm != ds->ds.algorithm) |
670 | return 0; | |
671 | if (dnssec_keytag(dnskey) != ds->ds.key_tag) | |
672 | return 0; | |
673 | ||
aa899317 LP |
674 | if (!dnssec_digest_supported(ds->ds.digest_type)) |
675 | return -EOPNOTSUPP; | |
676 | ||
2b442ac8 LP |
677 | switch (ds->ds.digest_type) { |
678 | ||
679 | case DNSSEC_DIGEST_SHA1: | |
680 | ||
681 | if (ds->ds.digest_size != 20) | |
682 | return 0; | |
683 | ||
684 | gcry_md_open(&md, GCRY_MD_SHA1, 0); | |
685 | break; | |
686 | ||
687 | case DNSSEC_DIGEST_SHA256: | |
688 | ||
689 | if (ds->ds.digest_size != 32) | |
690 | return 0; | |
691 | ||
692 | gcry_md_open(&md, GCRY_MD_SHA256, 0); | |
693 | break; | |
694 | ||
695 | default: | |
696 | assert_not_reached("Unknown digest"); | |
697 | } | |
698 | ||
699 | if (!md) | |
700 | return -EIO; | |
701 | ||
702 | r = dnssec_canonicalize(DNS_RESOURCE_KEY_NAME(dnskey->key), owner_name, sizeof(owner_name)); | |
703 | if (r < 0) | |
704 | goto finish; | |
705 | ||
706 | gcry_md_write(md, owner_name, r); | |
707 | md_add_uint16(md, dnskey->dnskey.flags); | |
708 | md_add_uint8(md, dnskey->dnskey.protocol); | |
709 | md_add_uint8(md, dnskey->dnskey.algorithm); | |
710 | gcry_md_write(md, dnskey->dnskey.key, dnskey->dnskey.key_size); | |
711 | ||
712 | result = gcry_md_read(md, 0); | |
713 | if (!result) { | |
714 | r = -EIO; | |
715 | goto finish; | |
716 | } | |
717 | ||
718 | r = memcmp(result, ds->ds.digest, ds->ds.digest_size) != 0; | |
719 | ||
720 | finish: | |
721 | gcry_md_close(md); | |
722 | return r; | |
723 | } | |
24710c48 | 724 | |
547973de LP |
725 | int dnssec_verify_dnskey_search(DnsResourceRecord *dnskey, DnsAnswer *validated_ds) { |
726 | DnsResourceRecord *ds; | |
727 | int r; | |
728 | ||
729 | assert(dnskey); | |
730 | ||
731 | if (dnskey->key->type != DNS_TYPE_DNSKEY) | |
732 | return 0; | |
733 | ||
734 | DNS_ANSWER_FOREACH(ds, validated_ds) { | |
735 | ||
736 | if (ds->key->type != DNS_TYPE_DS) | |
737 | continue; | |
738 | ||
739 | r = dnssec_verify_dnskey(dnskey, ds); | |
740 | if (r < 0) | |
741 | return r; | |
742 | if (r > 0) | |
743 | return 1; | |
744 | } | |
745 | ||
746 | return 0; | |
747 | } | |
748 | ||
24710c48 LP |
749 | static const char* const dnssec_mode_table[_DNSSEC_MODE_MAX] = { |
750 | [DNSSEC_NO] = "no", | |
751 | [DNSSEC_TRUST] = "trust", | |
752 | [DNSSEC_YES] = "yes", | |
753 | }; | |
754 | DEFINE_STRING_TABLE_LOOKUP(dnssec_mode, DnssecMode); | |
547973de LP |
755 | |
756 | static const char* const dnssec_result_table[_DNSSEC_RESULT_MAX] = { | |
757 | [DNSSEC_VALIDATED] = "validated", | |
758 | [DNSSEC_INVALID] = "invalid", | |
759 | [DNSSEC_UNSIGNED] = "unsigned", | |
760 | [DNSSEC_NO_SIGNATURE] = "no-signature", | |
761 | [DNSSEC_MISSING_KEY] = "missing-key", | |
762 | [DNSSEC_SIGNATURE_EXPIRED] = "signature-expired", | |
763 | [DNSSEC_FAILED_AUXILIARY] = "failed-auxiliary", | |
764 | }; | |
765 | DEFINE_STRING_TABLE_LOOKUP(dnssec_result, DnssecResult); |