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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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,
179 char** reason, struct module_qstate* qstate)
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 LDNS_SECTION_AUTHORITY, qstate);
190 if(d->security == sec_status_secure) {
191 rrset_update_sec_status(env->rrset_cache, nsec, *env->now);
198 val_nsec_prove_nodata_dsreply(struct module_env* env, struct val_env* ve,
199 struct query_info* qinfo, struct reply_info* rep,
200 struct key_entry_key* kkey, time_t* proof_ttl, char** reason,
201 struct module_qstate* qstate)
203 struct ub_packed_rrset_key* nsec = reply_find_rrset_section_ns(
204 rep, qinfo->qname, qinfo->qname_len, LDNS_RR_TYPE_NSEC,
208 uint8_t* wc = NULL, *ce = NULL;
210 struct ub_packed_rrset_key* wc_nsec = NULL;
212 /* If we have a NSEC at the same name, it must prove one
215 * 1) this is a delegation point and there is no DS
216 * 2) this is not a delegation point */
218 if(!nsec_verify_rrset(env, ve, nsec, kkey, reason, qstate)) {
219 verbose(VERB_ALGO, "NSEC RRset for the "
220 "referral did not verify.");
221 return sec_status_bogus;
223 sec = val_nsec_proves_no_ds(nsec, qinfo);
224 if(sec == sec_status_bogus) {
225 /* something was wrong. */
226 *reason = "NSEC does not prove absence of DS";
228 } else if(sec == sec_status_insecure) {
229 /* this wasn't a delegation point. */
231 } else if(sec == sec_status_secure) {
232 /* this proved no DS. */
233 *proof_ttl = ub_packed_rrset_ttl(nsec);
236 /* if unchecked, fall through to next proof */
239 /* Otherwise, there is no NSEC at qname. This could be an ENT.
240 * (ENT=empty non terminal). If not, this is broken. */
242 /* verify NSEC rrsets in auth section */
243 for(i=rep->an_numrrsets; i < rep->an_numrrsets+rep->ns_numrrsets;
245 if(rep->rrsets[i]->rk.type != htons(LDNS_RR_TYPE_NSEC))
247 if(!nsec_verify_rrset(env, ve, rep->rrsets[i], kkey, reason,
249 verbose(VERB_ALGO, "NSEC for empty non-terminal "
251 return sec_status_bogus;
253 if(nsec_proves_nodata(rep->rrsets[i], qinfo, &wc)) {
254 verbose(VERB_ALGO, "NSEC for empty non-terminal "
256 *proof_ttl = rrset_get_ttl(rep->rrsets[i]);
257 if(wc && dname_is_wild(rep->rrsets[i]->rk.dname))
258 wc_nsec = rep->rrsets[i];
261 if(val_nsec_proves_name_error(rep->rrsets[i], qinfo->qname)) {
262 ce = nsec_closest_encloser(qinfo->qname,
269 /* ce and wc must match */
270 if(query_dname_compare(wc, ce) != 0)
277 /* check if this is a delegation */
278 *reason = "NSEC for wildcard does not prove absence of DS";
279 return val_nsec_proves_no_ds(wc_nsec, qinfo);
281 /* valid nsec proves empty nonterminal */
282 return sec_status_insecure;
285 /* NSEC proof did not conclusively point to DS or no DS */
286 return sec_status_unchecked;
289 int nsec_proves_nodata(struct ub_packed_rrset_key* nsec,
290 struct query_info* qinfo, uint8_t** wc)
293 if(query_dname_compare(nsec->rk.dname, qinfo->qname) != 0) {
297 /* empty-non-terminal checking.
298 * Done before wildcard, because this is an exact match,
299 * and would prevent a wildcard from matching. */
301 /* If the nsec is proving that qname is an ENT, the nsec owner
302 * will be less than qname, and the next name will be a child
303 * domain of the qname. */
304 if(!nsec_get_next(nsec, &nm, &ln))
305 return 0; /* bad nsec */
306 if(dname_strict_subdomain_c(nm, qinfo->qname) &&
307 dname_canonical_compare(nsec->rk.dname,
309 return 1; /* proves ENT */
312 /* wildcard checking. */
314 /* If this is a wildcard NSEC, make sure that a) it was
315 * possible to have generated qname from the wildcard and
316 * b) the type map does not contain qtype. Note that this
317 * does NOT prove that this wildcard was the applicable
319 if(dname_is_wild(nsec->rk.dname)) {
320 /* the purported closest encloser. */
321 uint8_t* ce = nsec->rk.dname;
322 size_t ce_len = nsec->rk.dname_len;
323 dname_remove_label(&ce, &ce_len);
325 /* The qname must be a strict subdomain of the
326 * closest encloser, for the wildcard to apply
328 if(dname_strict_subdomain_c(qinfo->qname, ce)) {
329 /* here we have a matching NSEC for the qname,
330 * perform matching NSEC checks */
331 if(nsec_has_type(nsec, LDNS_RR_TYPE_CNAME)) {
332 /* should have gotten the wildcard CNAME */
335 if(nsec_has_type(nsec, LDNS_RR_TYPE_NS) &&
336 !nsec_has_type(nsec, LDNS_RR_TYPE_SOA)) {
337 /* wrong parentside (wildcard) NSEC used */
340 if(nsec_has_type(nsec, qinfo->qtype)) {
347 /* See if the next owner name covers a wildcard
348 * empty non-terminal. */
349 while (dname_canonical_compare(nsec->rk.dname, nm) < 0) {
350 /* wildcard does not apply if qname below
351 * the name that exists under the '*' */
352 if (dname_subdomain_c(qinfo->qname, nm))
354 /* but if it is a wildcard and qname is below
355 * it, then the wildcard applies. The wildcard
356 * is an empty nonterminal. nodata proven. */
357 if (dname_is_wild(nm)) {
360 dname_remove_label(&ce, &ce_len);
361 if(dname_strict_subdomain_c(qinfo->qname, ce)) {
366 dname_remove_label(&nm, &ln);
370 /* Otherwise, this NSEC does not prove ENT and is not a
371 * wildcard, so it does not prove NODATA. */
375 /* If the qtype exists, then we should have gotten it. */
376 if(nsec_has_type(nsec, qinfo->qtype)) {
380 /* if the name is a CNAME node, then we should have gotten the CNAME*/
381 if(nsec_has_type(nsec, LDNS_RR_TYPE_CNAME)) {
385 /* If an NS set exists at this name, and NOT a SOA (so this is a
386 * zone cut, not a zone apex), then we should have gotten a
387 * referral (or we just got the wrong NSEC).
388 * The reverse of this check is used when qtype is DS, since that
389 * must use the NSEC from above the zone cut. */
390 if(qinfo->qtype != LDNS_RR_TYPE_DS &&
391 nsec_has_type(nsec, LDNS_RR_TYPE_NS) &&
392 !nsec_has_type(nsec, LDNS_RR_TYPE_SOA)) {
394 } else if(qinfo->qtype == LDNS_RR_TYPE_DS &&
395 nsec_has_type(nsec, LDNS_RR_TYPE_SOA) &&
396 !dname_is_root(qinfo->qname)) {
404 val_nsec_proves_name_error(struct ub_packed_rrset_key* nsec, uint8_t* qname)
406 uint8_t* owner = nsec->rk.dname;
409 if(!nsec_get_next(nsec, &next, &nlen))
412 /* If NSEC owner == qname, then this NSEC proves that qname exists. */
413 if(query_dname_compare(qname, owner) == 0) {
417 /* If NSEC is a parent of qname, we need to check the type map
418 * If the parent name has a DNAME or is a delegation point, then
419 * this NSEC is being misused. */
420 if(dname_subdomain_c(qname, owner) &&
421 (nsec_has_type(nsec, LDNS_RR_TYPE_DNAME) ||
422 (nsec_has_type(nsec, LDNS_RR_TYPE_NS)
423 && !nsec_has_type(nsec, LDNS_RR_TYPE_SOA))
428 if(query_dname_compare(owner, next) == 0) {
429 /* this nsec is the only nsec */
430 /* zone.name NSEC zone.name, disproves everything else */
431 /* but only for subdomains of that zone */
432 if(dname_strict_subdomain_c(qname, next))
435 else if(dname_canonical_compare(owner, next) > 0) {
436 /* this is the last nsec, ....(bigger) NSEC zonename(smaller) */
437 /* the names after the last (owner) name do not exist
438 * there are no names before the zone name in the zone
439 * but the qname must be a subdomain of the zone name(next). */
440 if(dname_canonical_compare(owner, qname) < 0 &&
441 dname_strict_subdomain_c(qname, next))
444 /* regular NSEC, (smaller) NSEC (larger) */
445 if(dname_canonical_compare(owner, qname) < 0 &&
446 dname_canonical_compare(qname, next) < 0) {
453 int val_nsec_proves_insecuredelegation(struct ub_packed_rrset_key* nsec,
454 struct query_info* qinfo)
456 if(nsec_has_type(nsec, LDNS_RR_TYPE_NS) &&
457 !nsec_has_type(nsec, LDNS_RR_TYPE_DS) &&
458 !nsec_has_type(nsec, LDNS_RR_TYPE_SOA)) {
459 /* see if nsec signals an insecure delegation */
460 if(qinfo->qtype == LDNS_RR_TYPE_DS) {
461 /* if type is DS and qname is equal to nsec, then it
462 * is an exact match nsec, result not insecure */
463 if(dname_strict_subdomain_c(qinfo->qname,
467 if(dname_subdomain_c(qinfo->qname, nsec->rk.dname))
475 nsec_closest_encloser(uint8_t* qname, struct ub_packed_rrset_key* nsec)
479 uint8_t* common1, *common2;
480 if(!nsec_get_next(nsec, &next, &nlen))
482 /* longest common with owner or next name */
483 common1 = dname_get_shared_topdomain(nsec->rk.dname, qname);
484 common2 = dname_get_shared_topdomain(next, qname);
485 if(dname_count_labels(common1) > dname_count_labels(common2))
490 int val_nsec_proves_positive_wildcard(struct ub_packed_rrset_key* nsec,
491 struct query_info* qinf, uint8_t* wc)
494 /* 1) prove that qname doesn't exist and
495 * 2) that the correct wildcard was used
496 * nsec has been verified already. */
497 if(!val_nsec_proves_name_error(nsec, qinf->qname))
499 /* check wildcard name */
500 ce = nsec_closest_encloser(qinf->qname, nsec);
503 if(query_dname_compare(wc, ce) != 0) {
510 val_nsec_proves_no_wc(struct ub_packed_rrset_key* nsec, uint8_t* qname,
513 /* Determine if a NSEC record proves the non-existence of a
514 * wildcard that could have produced qname. */
516 uint8_t* ce = nsec_closest_encloser(qname, nsec);
519 uint8_t buf[LDNS_MAX_DOMAINLEN+3];
522 /* we can subtract the closest encloser count - since that is the
523 * largest shared topdomain with owner and next NSEC name,
524 * because the NSEC is no proof for names shorter than the owner
526 labs = dname_count_labels(qname) - dname_count_labels(ce);
529 /* i is number of labels to strip off qname, prepend * wild */
532 dname_remove_labels(&strip, &striplen, labs);
533 if(striplen > LDNS_MAX_DOMAINLEN-2)
534 return 0; /* too long to prepend wildcard */
536 buf[1] = (uint8_t)'*';
537 memmove(buf+2, strip, striplen);
538 if(val_nsec_proves_name_error(nsec, buf)) {
546 * Find shared topdomain that exists
549 dlv_topdomain(struct ub_packed_rrset_key* nsec, uint8_t* qname,
550 uint8_t** nm, size_t* nm_len)
552 /* make sure reply is part of nm */
553 /* take shared topdomain with left of NSEC. */
555 /* because, if empty nonterminal, then right is subdomain of qname.
556 * and any shared topdomain would be empty nonterminals.
558 * If nxdomain, then the right is bigger, and could have an
559 * interesting shared topdomain, but if it does have one, it is
560 * an empty nonterminal. An empty nonterminal shared with the left
563 uint8_t* common = dname_get_shared_topdomain(qname, nsec->rk.dname);
564 n = dname_count_labels(*nm) - dname_count_labels(common);
565 dname_remove_labels(nm, nm_len, n);
568 int val_nsec_check_dlv(struct query_info* qinfo,
569 struct reply_info* rep, uint8_t** nm, size_t* nm_len)
574 /* we should now have a NOERROR/NODATA or NXDOMAIN message */
575 if(rep->an_numrrsets != 0) {
578 /* is this NOERROR ? */
579 if(FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NOERROR) {
580 /* it can be a plain NSEC match - go up one more level. */
581 /* or its an empty nonterminal - go up to nonempty level */
582 for(i=0; i<rep->ns_numrrsets; i++) {
583 if(htons(rep->rrsets[i]->rk.type)!=LDNS_RR_TYPE_NSEC ||
584 !nsec_get_next(rep->rrsets[i], &next, &nlen))
586 c = dname_canonical_compare(
587 rep->rrsets[i]->rk.dname, qinfo->qname);
590 if(nsec_has_type(rep->rrsets[i],
593 dname_remove_label(nm, nm_len);
596 dname_strict_subdomain_c(next, qinfo->qname)) {
598 dlv_topdomain(rep->rrsets[i], qinfo->qname,
606 /* is this NXDOMAIN ? */
607 if(FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NXDOMAIN) {
608 /* find the qname denial NSEC record. It can tell us
609 * a closest encloser name; or that we not need bother */
610 for(i=0; i<rep->ns_numrrsets; i++) {
611 if(htons(rep->rrsets[i]->rk.type) != LDNS_RR_TYPE_NSEC)
613 if(val_nsec_proves_name_error(rep->rrsets[i],
615 log_nametypeclass(VERB_ALGO, "topdomain on",
616 rep->rrsets[i]->rk.dname,
617 ntohs(rep->rrsets[i]->rk.type), 0);
618 dlv_topdomain(rep->rrsets[i], qinfo->qname,