2 * validator/val_nsec.c - validator NSEC denial of existence functions.
4 * Copyright (c) 2007, NLnet Labs. All rights reserved.
6 * This software is open source.
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9 * modification, are permitted provided that the following conditions
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13 * this list of conditions and the following disclaimer.
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16 * this list of conditions and the following disclaimer in the documentation
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23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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39 * This file contains helper functions for the validator module.
40 * The functions help with NSEC checking, the different NSEC proofs
41 * for denial of existence, and proofs for presence of types.
44 #include "validator/val_nsec.h"
45 #include "validator/val_utils.h"
46 #include "util/data/msgreply.h"
47 #include "util/data/dname.h"
48 #include "util/net_help.h"
49 #include "util/module.h"
50 #include "services/cache/rrset.h"
52 /** get ttl of rrset */
54 rrset_get_ttl(struct ub_packed_rrset_key* k)
56 struct packed_rrset_data* d = (struct packed_rrset_data*)k->entry.data;
61 nsecbitmap_has_type_rdata(uint8_t* bitmap, size_t len, uint16_t type)
63 /* Check type present in NSEC typemap with bitmap arg */
64 /* bitmasks for determining type-lowerbits presence */
65 uint8_t masks[8] = {0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01};
66 uint8_t type_window = type>>8;
67 uint8_t type_low = type&0xff;
69 /* read each of the type bitmap windows and see if the searched
70 * type is amongst it */
72 if(len < 3) /* bad window, at least window# winlen bitmap */
77 if(len < winlen || winlen < 1 || winlen > 32)
78 return 0; /* bad window length */
79 if(win == type_window) {
80 /* search window bitmap for the correct byte */
81 /* mybyte is 0 if we need the first byte */
82 size_t mybyte = type_low>>3;
84 return 0; /* window too short */
85 return (int)(bitmap[mybyte] & masks[type_low&0x7]);
87 /* not the window we are looking for */
92 /* end of bitmap reached, no type found */
97 nsec_has_type(struct ub_packed_rrset_key* nsec, uint16_t type)
99 struct packed_rrset_data* d = (struct packed_rrset_data*)nsec->
102 if(!d || d->count == 0 || d->rr_len[0] < 2+1)
104 len = dname_valid(d->rr_data[0]+2, d->rr_len[0]-2);
107 return nsecbitmap_has_type_rdata(d->rr_data[0]+2+len,
108 d->rr_len[0]-2-len, type);
112 * Get next owner name from nsec record
113 * @param nsec: the nsec RRset.
114 * If there are multiple RRs, then this will only return one of them.
115 * @param nm: the next name is returned.
116 * @param ln: length of nm is returned.
117 * @return false on a bad NSEC RR (too short, malformed dname).
120 nsec_get_next(struct ub_packed_rrset_key* nsec, uint8_t** nm, size_t* ln)
122 struct packed_rrset_data* d = (struct packed_rrset_data*)nsec->
124 if(!d || d->count == 0 || d->rr_len[0] < 2+1) {
129 *nm = d->rr_data[0]+2;
130 *ln = dname_valid(*nm, d->rr_len[0]-2);
140 * For an NSEC that matches the DS queried for, check absence of DS type.
142 * @param nsec: NSEC for proof, must be trusted.
143 * @param qinfo: what is queried for.
144 * @return if secure the nsec proves that no DS is present, or
145 * insecure if it proves it is not a delegation point.
146 * or bogus if something was wrong.
148 static enum sec_status
149 val_nsec_proves_no_ds(struct ub_packed_rrset_key* nsec,
150 struct query_info* qinfo)
152 log_assert(qinfo->qtype == LDNS_RR_TYPE_DS);
153 log_assert(ntohs(nsec->rk.type) == LDNS_RR_TYPE_NSEC);
155 if(nsec_has_type(nsec, LDNS_RR_TYPE_SOA) && qinfo->qname_len != 1) {
156 /* SOA present means that this is the NSEC from the child,
157 * not the parent (so it is the wrong one). */
158 return sec_status_bogus;
160 if(nsec_has_type(nsec, LDNS_RR_TYPE_DS)) {
161 /* DS present means that there should have been a positive
162 * response to the DS query, so there is something wrong. */
163 return sec_status_bogus;
166 if(!nsec_has_type(nsec, LDNS_RR_TYPE_NS)) {
167 /* If there is no NS at this point at all, then this
168 * doesn't prove anything one way or the other. */
169 return sec_status_insecure;
171 /* Otherwise, this proves no DS. */
172 return sec_status_secure;
175 /** check security status from cache or verify rrset, returns true if secure */
177 nsec_verify_rrset(struct module_env* env, struct val_env* ve,
178 struct ub_packed_rrset_key* nsec, struct key_entry_key* kkey,
181 struct packed_rrset_data* d = (struct packed_rrset_data*)
183 if(d->security == sec_status_secure)
185 rrset_check_sec_status(env->rrset_cache, nsec, *env->now);
186 if(d->security == sec_status_secure)
188 d->security = val_verify_rrset_entry(env, ve, nsec, kkey, reason);
189 if(d->security == sec_status_secure) {
190 rrset_update_sec_status(env->rrset_cache, nsec, *env->now);
197 val_nsec_prove_nodata_dsreply(struct module_env* env, struct val_env* ve,
198 struct query_info* qinfo, struct reply_info* rep,
199 struct key_entry_key* kkey, time_t* proof_ttl, char** reason)
201 struct ub_packed_rrset_key* nsec = reply_find_rrset_section_ns(
202 rep, qinfo->qname, qinfo->qname_len, LDNS_RR_TYPE_NSEC,
206 uint8_t* wc = NULL, *ce = NULL;
208 struct ub_packed_rrset_key* wc_nsec = NULL;
210 /* If we have a NSEC at the same name, it must prove one
213 * 1) this is a delegation point and there is no DS
214 * 2) this is not a delegation point */
216 if(!nsec_verify_rrset(env, ve, nsec, kkey, reason)) {
217 verbose(VERB_ALGO, "NSEC RRset for the "
218 "referral did not verify.");
219 return sec_status_bogus;
221 sec = val_nsec_proves_no_ds(nsec, qinfo);
222 if(sec == sec_status_bogus) {
223 /* something was wrong. */
224 *reason = "NSEC does not prove absence of DS";
226 } else if(sec == sec_status_insecure) {
227 /* this wasn't a delegation point. */
229 } else if(sec == sec_status_secure) {
230 /* this proved no DS. */
231 *proof_ttl = ub_packed_rrset_ttl(nsec);
234 /* if unchecked, fall through to next proof */
237 /* Otherwise, there is no NSEC at qname. This could be an ENT.
238 * (ENT=empty non terminal). If not, this is broken. */
240 /* verify NSEC rrsets in auth section */
241 for(i=rep->an_numrrsets; i < rep->an_numrrsets+rep->ns_numrrsets;
243 if(rep->rrsets[i]->rk.type != htons(LDNS_RR_TYPE_NSEC))
245 if(!nsec_verify_rrset(env, ve, rep->rrsets[i], kkey, reason)) {
246 verbose(VERB_ALGO, "NSEC for empty non-terminal "
248 return sec_status_bogus;
250 if(nsec_proves_nodata(rep->rrsets[i], qinfo, &wc)) {
251 verbose(VERB_ALGO, "NSEC for empty non-terminal "
253 *proof_ttl = rrset_get_ttl(rep->rrsets[i]);
254 if(wc && dname_is_wild(rep->rrsets[i]->rk.dname))
255 wc_nsec = rep->rrsets[i];
258 if(val_nsec_proves_name_error(rep->rrsets[i], qinfo->qname)) {
259 ce = nsec_closest_encloser(qinfo->qname,
266 /* ce and wc must match */
267 if(query_dname_compare(wc, ce) != 0)
274 /* check if this is a delegation */
275 *reason = "NSEC for wildcard does not prove absence of DS";
276 return val_nsec_proves_no_ds(wc_nsec, qinfo);
278 /* valid nsec proves empty nonterminal */
279 return sec_status_insecure;
282 /* NSEC proof did not conclusively point to DS or no DS */
283 return sec_status_unchecked;
286 int nsec_proves_nodata(struct ub_packed_rrset_key* nsec,
287 struct query_info* qinfo, uint8_t** wc)
290 if(query_dname_compare(nsec->rk.dname, qinfo->qname) != 0) {
294 /* empty-non-terminal checking.
295 * Done before wildcard, because this is an exact match,
296 * and would prevent a wildcard from matching. */
298 /* If the nsec is proving that qname is an ENT, the nsec owner
299 * will be less than qname, and the next name will be a child
300 * domain of the qname. */
301 if(!nsec_get_next(nsec, &nm, &ln))
302 return 0; /* bad nsec */
303 if(dname_strict_subdomain_c(nm, qinfo->qname) &&
304 dname_canonical_compare(nsec->rk.dname,
306 return 1; /* proves ENT */
309 /* wildcard checking. */
311 /* If this is a wildcard NSEC, make sure that a) it was
312 * possible to have generated qname from the wildcard and
313 * b) the type map does not contain qtype. Note that this
314 * does NOT prove that this wildcard was the applicable
316 if(dname_is_wild(nsec->rk.dname)) {
317 /* the purported closest encloser. */
318 uint8_t* ce = nsec->rk.dname;
319 size_t ce_len = nsec->rk.dname_len;
320 dname_remove_label(&ce, &ce_len);
322 /* The qname must be a strict subdomain of the
323 * closest encloser, for the wildcard to apply
325 if(dname_strict_subdomain_c(qinfo->qname, ce)) {
326 /* here we have a matching NSEC for the qname,
327 * perform matching NSEC checks */
328 if(nsec_has_type(nsec, LDNS_RR_TYPE_CNAME)) {
329 /* should have gotten the wildcard CNAME */
332 if(nsec_has_type(nsec, LDNS_RR_TYPE_NS) &&
333 !nsec_has_type(nsec, LDNS_RR_TYPE_SOA)) {
334 /* wrong parentside (wildcard) NSEC used */
337 if(nsec_has_type(nsec, qinfo->qtype)) {
344 /* See if the next owner name covers a wildcard
345 * empty non-terminal. */
346 while (dname_strict_subdomain_c(nm, nsec->rk.dname)) {
347 /* wildcard does not apply if qname below
348 * the name that exists under the '*' */
349 if (dname_subdomain_c(qinfo->qname, nm))
351 /* but if it is a wildcard and qname is below
352 * it, then the wildcard applies. The wildcard
353 * is an empty nonterminal. nodata proven. */
354 if (dname_is_wild(nm)) {
357 dname_remove_label(&ce, &ce_len);
358 if(dname_strict_subdomain_c(qinfo->qname, ce)) {
363 dname_remove_label(&nm, &ln);
367 /* Otherwise, this NSEC does not prove ENT and is not a
368 * wildcard, so it does not prove NODATA. */
372 /* If the qtype exists, then we should have gotten it. */
373 if(nsec_has_type(nsec, qinfo->qtype)) {
377 /* if the name is a CNAME node, then we should have gotten the CNAME*/
378 if(nsec_has_type(nsec, LDNS_RR_TYPE_CNAME)) {
382 /* If an NS set exists at this name, and NOT a SOA (so this is a
383 * zone cut, not a zone apex), then we should have gotten a
384 * referral (or we just got the wrong NSEC).
385 * The reverse of this check is used when qtype is DS, since that
386 * must use the NSEC from above the zone cut. */
387 if(qinfo->qtype != LDNS_RR_TYPE_DS &&
388 nsec_has_type(nsec, LDNS_RR_TYPE_NS) &&
389 !nsec_has_type(nsec, LDNS_RR_TYPE_SOA)) {
391 } else if(qinfo->qtype == LDNS_RR_TYPE_DS &&
392 nsec_has_type(nsec, LDNS_RR_TYPE_SOA) &&
393 !dname_is_root(qinfo->qname)) {
401 val_nsec_proves_name_error(struct ub_packed_rrset_key* nsec, uint8_t* qname)
403 uint8_t* owner = nsec->rk.dname;
406 if(!nsec_get_next(nsec, &next, &nlen))
409 /* If NSEC owner == qname, then this NSEC proves that qname exists. */
410 if(query_dname_compare(qname, owner) == 0) {
414 /* If NSEC is a parent of qname, we need to check the type map
415 * If the parent name has a DNAME or is a delegation point, then
416 * this NSEC is being misused. */
417 if(dname_subdomain_c(qname, owner) &&
418 (nsec_has_type(nsec, LDNS_RR_TYPE_DNAME) ||
419 (nsec_has_type(nsec, LDNS_RR_TYPE_NS)
420 && !nsec_has_type(nsec, LDNS_RR_TYPE_SOA))
425 if(query_dname_compare(owner, next) == 0) {
426 /* this nsec is the only nsec */
427 /* zone.name NSEC zone.name, disproves everything else */
428 /* but only for subdomains of that zone */
429 if(dname_strict_subdomain_c(qname, next))
432 else if(dname_canonical_compare(owner, next) > 0) {
433 /* this is the last nsec, ....(bigger) NSEC zonename(smaller) */
434 /* the names after the last (owner) name do not exist
435 * there are no names before the zone name in the zone
436 * but the qname must be a subdomain of the zone name(next). */
437 if(dname_canonical_compare(owner, qname) < 0 &&
438 dname_strict_subdomain_c(qname, next))
441 /* regular NSEC, (smaller) NSEC (larger) */
442 if(dname_canonical_compare(owner, qname) < 0 &&
443 dname_canonical_compare(qname, next) < 0) {
450 int val_nsec_proves_insecuredelegation(struct ub_packed_rrset_key* nsec,
451 struct query_info* qinfo)
453 if(nsec_has_type(nsec, LDNS_RR_TYPE_NS) &&
454 !nsec_has_type(nsec, LDNS_RR_TYPE_DS) &&
455 !nsec_has_type(nsec, LDNS_RR_TYPE_SOA)) {
456 /* see if nsec signals an insecure delegation */
457 if(qinfo->qtype == LDNS_RR_TYPE_DS) {
458 /* if type is DS and qname is equal to nsec, then it
459 * is an exact match nsec, result not insecure */
460 if(dname_strict_subdomain_c(qinfo->qname,
464 if(dname_subdomain_c(qinfo->qname, nsec->rk.dname))
472 nsec_closest_encloser(uint8_t* qname, struct ub_packed_rrset_key* nsec)
476 uint8_t* common1, *common2;
477 if(!nsec_get_next(nsec, &next, &nlen))
479 /* longest common with owner or next name */
480 common1 = dname_get_shared_topdomain(nsec->rk.dname, qname);
481 common2 = dname_get_shared_topdomain(next, qname);
482 if(dname_count_labels(common1) > dname_count_labels(common2))
487 int val_nsec_proves_positive_wildcard(struct ub_packed_rrset_key* nsec,
488 struct query_info* qinf, uint8_t* wc)
491 /* 1) prove that qname doesn't exist and
492 * 2) that the correct wildcard was used
493 * nsec has been verified already. */
494 if(!val_nsec_proves_name_error(nsec, qinf->qname))
496 /* check wildcard name */
497 ce = nsec_closest_encloser(qinf->qname, nsec);
500 if(query_dname_compare(wc, ce) != 0) {
507 val_nsec_proves_no_wc(struct ub_packed_rrset_key* nsec, uint8_t* qname,
510 /* Determine if a NSEC record proves the non-existence of a
511 * wildcard that could have produced qname. */
514 uint8_t* ce = nsec_closest_encloser(qname, nsec);
517 uint8_t buf[LDNS_MAX_DOMAINLEN+3];
520 /* we can subtract the closest encloser count - since that is the
521 * largest shared topdomain with owner and next NSEC name,
522 * because the NSEC is no proof for names shorter than the owner
524 labs = dname_count_labels(qname) - dname_count_labels(ce);
526 for(i=labs; i>0; i--) {
527 /* i is number of labels to strip off qname, prepend * wild */
530 dname_remove_labels(&strip, &striplen, i);
531 if(striplen > LDNS_MAX_DOMAINLEN-2)
532 continue; /* too long to prepend wildcard */
534 buf[1] = (uint8_t)'*';
535 memmove(buf+2, strip, striplen);
536 if(val_nsec_proves_name_error(nsec, buf)) {
544 * Find shared topdomain that exists
547 dlv_topdomain(struct ub_packed_rrset_key* nsec, uint8_t* qname,
548 uint8_t** nm, size_t* nm_len)
550 /* make sure reply is part of nm */
551 /* take shared topdomain with left of NSEC. */
553 /* because, if empty nonterminal, then right is subdomain of qname.
554 * and any shared topdomain would be empty nonterminals.
556 * If nxdomain, then the right is bigger, and could have an
557 * interesting shared topdomain, but if it does have one, it is
558 * an empty nonterminal. An empty nonterminal shared with the left
561 uint8_t* common = dname_get_shared_topdomain(qname, nsec->rk.dname);
562 n = dname_count_labels(*nm) - dname_count_labels(common);
563 dname_remove_labels(nm, nm_len, n);
566 int val_nsec_check_dlv(struct query_info* qinfo,
567 struct reply_info* rep, uint8_t** nm, size_t* nm_len)
572 /* we should now have a NOERROR/NODATA or NXDOMAIN message */
573 if(rep->an_numrrsets != 0) {
576 /* is this NOERROR ? */
577 if(FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NOERROR) {
578 /* it can be a plain NSEC match - go up one more level. */
579 /* or its an empty nonterminal - go up to nonempty level */
580 for(i=0; i<rep->ns_numrrsets; i++) {
581 if(htons(rep->rrsets[i]->rk.type)!=LDNS_RR_TYPE_NSEC ||
582 !nsec_get_next(rep->rrsets[i], &next, &nlen))
584 c = dname_canonical_compare(
585 rep->rrsets[i]->rk.dname, qinfo->qname);
588 if(nsec_has_type(rep->rrsets[i],
591 dname_remove_label(nm, nm_len);
594 dname_strict_subdomain_c(next, qinfo->qname)) {
596 dlv_topdomain(rep->rrsets[i], qinfo->qname,
604 /* is this NXDOMAIN ? */
605 if(FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NXDOMAIN) {
606 /* find the qname denial NSEC record. It can tell us
607 * a closest encloser name; or that we not need bother */
608 for(i=0; i<rep->ns_numrrsets; i++) {
609 if(htons(rep->rrsets[i]->rk.type) != LDNS_RR_TYPE_NSEC)
611 if(val_nsec_proves_name_error(rep->rrsets[i],
613 log_nametypeclass(VERB_ALGO, "topdomain on",
614 rep->rrsets[i]->rk.dname,
615 ntohs(rep->rrsets[i]->rk.type), 0);
616 dlv_topdomain(rep->rrsets[i], qinfo->qname,