/* * validator/val_utils.c - validator utility functions. * * Copyright (c) 2007, NLnet Labs. All rights reserved. * * This software is open source. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * Neither the name of the NLNET LABS nor the names of its contributors may * be used to endorse or promote products derived from this software without * specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /** * \file * * This file contains helper functions for the validator module. */ #include "config.h" #include "validator/val_utils.h" #include "validator/validator.h" #include "validator/val_kentry.h" #include "validator/val_sigcrypt.h" #include "validator/val_anchor.h" #include "services/cache/rrset.h" #include "util/data/msgreply.h" #include "util/data/packed_rrset.h" #include "util/data/dname.h" #include "util/net_help.h" #include "util/module.h" #include "util/regional.h" enum val_classification val_classify_response(uint16_t query_flags, struct query_info* origqinf, struct query_info* qinf, struct reply_info* rep, size_t skip) { int rcode = (int)FLAGS_GET_RCODE(rep->flags); size_t i; /* Normal Name Error's are easy to detect -- but don't mistake a CNAME * chain ending in NXDOMAIN. */ if(rcode == LDNS_RCODE_NXDOMAIN && rep->an_numrrsets == 0) return VAL_CLASS_NAMEERROR; /* check for referral: nonRD query and it looks like a nodata */ if(!(query_flags&BIT_RD) && rep->an_numrrsets == 0 && rcode == LDNS_RCODE_NOERROR) { /* SOA record in auth indicates it is NODATA instead. * All validation requiring NODATA messages have SOA in * authority section. */ /* uses fact that answer section is empty */ int saw_ns = 0; for(i=0; ins_numrrsets; i++) { if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_SOA) return VAL_CLASS_NODATA; if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_DS) return VAL_CLASS_REFERRAL; if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_NS) saw_ns = 1; } return saw_ns?VAL_CLASS_REFERRAL:VAL_CLASS_NODATA; } /* root referral where NS set is in the answer section */ if(!(query_flags&BIT_RD) && rep->ns_numrrsets == 0 && rep->an_numrrsets == 1 && rcode == LDNS_RCODE_NOERROR && ntohs(rep->rrsets[0]->rk.type) == LDNS_RR_TYPE_NS && query_dname_compare(rep->rrsets[0]->rk.dname, origqinf->qname) != 0) return VAL_CLASS_REFERRAL; /* dump bad messages */ if(rcode != LDNS_RCODE_NOERROR) return VAL_CLASS_UNKNOWN; log_assert(rcode == LDNS_RCODE_NOERROR); /* next check if the skip into the answer section shows no answer */ if(skip>0 && rep->an_numrrsets <= skip) return VAL_CLASS_CNAMENOANSWER; /* Next is NODATA */ if(rep->an_numrrsets == 0) return VAL_CLASS_NODATA; /* We distinguish between CNAME response and other positive/negative * responses because CNAME answers require extra processing. */ /* We distinguish between ANY and CNAME or POSITIVE because * ANY responses are validated differently. */ if(qinf->qtype == LDNS_RR_TYPE_ANY) return VAL_CLASS_ANY; /* Note that DNAMEs will be ignored here, unless qtype=DNAME. Unless * qtype=CNAME, this will yield a CNAME response. */ for(i=skip; ian_numrrsets; i++) { if(ntohs(rep->rrsets[i]->rk.type) == qinf->qtype) return VAL_CLASS_POSITIVE; if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_CNAME) return VAL_CLASS_CNAME; } log_dns_msg("validator: error. failed to classify response message: ", qinf, rep); return VAL_CLASS_UNKNOWN; } /** Get signer name from RRSIG */ static void rrsig_get_signer(uint8_t* data, size_t len, uint8_t** sname, size_t* slen) { /* RRSIG rdata is not allowed to be compressed, it is stored * uncompressed in memory as well, so return a ptr to the name */ if(len < 21) { /* too short RRSig: * short, byte, byte, long, long, long, short, "." is * 2 1 1 4 4 4 2 1 = 19 * and a skip of 18 bytes to the name. * +2 for the rdatalen is 21 bytes len for root label */ *sname = NULL; *slen = 0; return; } data += 20; /* skip the fixed size bits */ len -= 20; *slen = dname_valid(data, len); if(!*slen) { /* bad dname in this rrsig. */ *sname = NULL; return; } *sname = data; } void val_find_rrset_signer(struct ub_packed_rrset_key* rrset, uint8_t** sname, size_t* slen) { struct packed_rrset_data* d = (struct packed_rrset_data*) rrset->entry.data; /* return signer for first signature, or NULL */ if(d->rrsig_count == 0) { *sname = NULL; *slen = 0; return; } /* get rrsig signer name out of the signature */ rrsig_get_signer(d->rr_data[d->count], d->rr_len[d->count], sname, slen); } /** * Find best signer name in this set of rrsigs. * @param rrset: which rrsigs to look through. * @param qinf: the query name that needs validation. * @param signer_name: the best signer_name. Updated if a better one is found. * @param signer_len: length of signer name. * @param matchcount: count of current best name (starts at 0 for no match). * Updated if match is improved. */ static void val_find_best_signer(struct ub_packed_rrset_key* rrset, struct query_info* qinf, uint8_t** signer_name, size_t* signer_len, int* matchcount) { struct packed_rrset_data* d = (struct packed_rrset_data*) rrset->entry.data; uint8_t* sign; size_t i; int m; for(i=d->count; icount+d->rrsig_count; i++) { sign = d->rr_data[i]+2+18; /* look at signatures that are valid (long enough), * and have a signer name that is a superdomain of qname, * and then check the number of labels in the shared topdomain * improve the match if possible */ if(d->rr_len[i] > 2+19 && /* rdata, sig + root label*/ dname_subdomain_c(qinf->qname, sign)) { (void)dname_lab_cmp(qinf->qname, dname_count_labels(qinf->qname), sign, dname_count_labels(sign), &m); if(m > *matchcount) { *matchcount = m; *signer_name = sign; (void)dname_count_size_labels(*signer_name, signer_len); } } } } void val_find_signer(enum val_classification subtype, struct query_info* qinf, struct reply_info* rep, size_t skip, uint8_t** signer_name, size_t* signer_len) { size_t i; if(subtype == VAL_CLASS_POSITIVE || subtype == VAL_CLASS_ANY) { /* check for the answer rrset */ for(i=skip; ian_numrrsets; i++) { if(query_dname_compare(qinf->qname, rep->rrsets[i]->rk.dname) == 0) { val_find_rrset_signer(rep->rrsets[i], signer_name, signer_len); return; } } *signer_name = NULL; *signer_len = 0; } else if(subtype == VAL_CLASS_CNAME) { /* check for the first signed cname/dname rrset */ for(i=skip; ian_numrrsets; i++) { val_find_rrset_signer(rep->rrsets[i], signer_name, signer_len); if(*signer_name) return; } *signer_name = NULL; *signer_len = 0; } else if(subtype == VAL_CLASS_NAMEERROR || subtype == VAL_CLASS_NODATA) { /*Check to see if the AUTH section NSEC record(s) have rrsigs*/ for(i=rep->an_numrrsets; i< rep->an_numrrsets+rep->ns_numrrsets; i++) { if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_NSEC || ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_NSEC3) { val_find_rrset_signer(rep->rrsets[i], signer_name, signer_len); return; } } } else if(subtype == VAL_CLASS_CNAMENOANSWER) { /* find closest superdomain signer name in authority section * NSEC and NSEC3s */ int matchcount = 0; *signer_name = NULL; *signer_len = 0; for(i=rep->an_numrrsets; ian_numrrsets+rep-> ns_numrrsets; i++) { if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_NSEC || ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_NSEC3) { val_find_best_signer(rep->rrsets[i], qinf, signer_name, signer_len, &matchcount); } } } else if(subtype == VAL_CLASS_REFERRAL) { /* find keys for the item at skip */ if(skip < rep->rrset_count) { val_find_rrset_signer(rep->rrsets[skip], signer_name, signer_len); return; } *signer_name = NULL; *signer_len = 0; } else { verbose(VERB_QUERY, "find_signer: could not find signer name" " for unknown type response"); *signer_name = NULL; *signer_len = 0; } } /** return number of rrs in an rrset */ static size_t rrset_get_count(struct ub_packed_rrset_key* rrset) { struct packed_rrset_data* d = (struct packed_rrset_data*) rrset->entry.data; if(!d) return 0; return d->count; } /** return TTL of rrset */ static uint32_t rrset_get_ttl(struct ub_packed_rrset_key* rrset) { struct packed_rrset_data* d = (struct packed_rrset_data*) rrset->entry.data; if(!d) return 0; return d->ttl; } enum sec_status val_verify_rrset(struct module_env* env, struct val_env* ve, struct ub_packed_rrset_key* rrset, struct ub_packed_rrset_key* keys) { enum sec_status sec; struct packed_rrset_data* d = (struct packed_rrset_data*)rrset-> entry.data; if(d->security == sec_status_secure) { /* re-verify all other statuses, because keyset may change*/ log_nametypeclass(VERB_ALGO, "verify rrset cached", rrset->rk.dname, ntohs(rrset->rk.type), ntohs(rrset->rk.rrset_class)); return d->security; } /* check in the cache if verification has already been done */ rrset_check_sec_status(env->rrset_cache, rrset, *env->now); if(d->security == sec_status_secure) { log_nametypeclass(VERB_ALGO, "verify rrset from cache", rrset->rk.dname, ntohs(rrset->rk.type), ntohs(rrset->rk.rrset_class)); return d->security; } log_nametypeclass(VERB_ALGO, "verify rrset", rrset->rk.dname, ntohs(rrset->rk.type), ntohs(rrset->rk.rrset_class)); sec = dnskeyset_verify_rrset(env, ve, rrset, keys); verbose(VERB_ALGO, "verify result: %s", sec_status_to_string(sec)); regional_free_all(env->scratch); /* update rrset security status * only improves security status * and bogus is set only once, even if we rechecked the status */ if(sec > d->security) { d->security = sec; if(sec == sec_status_secure) d->trust = rrset_trust_validated; else if(sec == sec_status_bogus) { /* update ttl for rrset to fixed value. */ d->ttl = ve->bogus_ttl; /* leave RR specific TTL: not used for determine * if RRset timed out and clients see proper value. */ } /* if status updated - store in cache for reuse */ rrset_update_sec_status(env->rrset_cache, rrset, *env->now); } return sec; } enum sec_status val_verify_rrset_entry(struct module_env* env, struct val_env* ve, struct ub_packed_rrset_key* rrset, struct key_entry_key* kkey) { /* temporary dnskey rrset-key */ struct ub_packed_rrset_key dnskey; struct key_entry_data* kd = (struct key_entry_data*)kkey->entry.data; enum sec_status sec; dnskey.rk.type = htons(kd->rrset_type); dnskey.rk.rrset_class = htons(kkey->key_class); dnskey.rk.flags = 0; dnskey.rk.dname = kkey->name; dnskey.rk.dname_len = kkey->namelen; dnskey.entry.key = &dnskey; dnskey.entry.data = kd->rrset_data; sec = val_verify_rrset(env, ve, rrset, &dnskey); return sec; } /** verify that a DS RR hashes to a key and that key signs the set */ static enum sec_status verify_dnskeys_with_ds_rr(struct module_env* env, struct val_env* ve, struct ub_packed_rrset_key* dnskey_rrset, struct ub_packed_rrset_key* ds_rrset, size_t ds_idx) { enum sec_status sec = sec_status_bogus; size_t i, num; num = rrset_get_count(dnskey_rrset); for(i=0; irk.dname_len != ds_rrset->rk.dname_len || query_dname_compare(dnskey_rrset->rk.dname, ds_rrset->rk.dname) != 0) { verbose(VERB_QUERY, "DNSKEY RRset did not match DS RRset " "by name"); return key_entry_create_bad(region, ds_rrset->rk.dname, ds_rrset->rk.dname_len, ntohs(ds_rrset->rk.rrset_class)); } num = rrset_get_count(ds_rrset); for(i=0; irk.dname, ds_rrset->rk.dname_len, ntohs(ds_rrset->rk.rrset_class), dnskey_rrset, *env->now); } } /* None of the DS's worked out. */ /* If no DSs were understandable, then this is OK. */ if(!has_useful_ds) { verbose(VERB_ALGO, "No usable DS records were found -- " "treating as insecure."); return key_entry_create_null(region, ds_rrset->rk.dname, ds_rrset->rk.dname_len, ntohs(ds_rrset->rk.rrset_class), rrset_get_ttl(ds_rrset), *env->now); } /* If any were understandable, then it is bad. */ verbose(VERB_QUERY, "Failed to match any usable DS to a DNSKEY."); return key_entry_create_bad(region, ds_rrset->rk.dname, ds_rrset->rk.dname_len, ntohs(ds_rrset->rk.rrset_class)); } int val_dsset_isusable(struct ub_packed_rrset_key* ds_rrset) { size_t i; for(i=0; irr_len[sig] < 2+4) return 0; /* bad sig length */ return d->rr_data[sig][2+3]; } int val_rrset_wildcard(struct ub_packed_rrset_key* rrset, uint8_t** wc) { struct packed_rrset_data* d = (struct packed_rrset_data*)rrset-> entry.data; uint8_t labcount; int labdiff; size_t i; if(d->rrsig_count == 0) { return 1; } labcount = rrsig_get_labcount(d, d->count + 0); /* check rest of signatures identical */ for(i=1; irrsig_count; i++) { if(labcount != rrsig_get_labcount(d, d->count + i)) { return 0; } } /* OK the rrsigs check out */ /* if the RRSIG label count is shorter than the number of actual * labels, then this rrset was synthesized from a wildcard. * Note that the RRSIG label count doesn't count the root label. */ labdiff = (dname_count_labels(rrset->rk.dname) - 1) - (int)labcount; if(labdiff > 0) { size_t wl = rrset->rk.dname_len; *wc = rrset->rk.dname; dname_remove_labels(wc, &wl, labdiff); return 1; } return 1; } int val_chase_cname(struct query_info* qchase, struct reply_info* rep, size_t* cname_skip) { size_t i; /* skip any DNAMEs, go to the CNAME for next part */ for(i = *cname_skip; i < rep->an_numrrsets; i++) { if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_CNAME && query_dname_compare(qchase->qname, rep->rrsets[i]-> rk.dname) == 0) { qchase->qname = NULL; get_cname_target(rep->rrsets[i], &qchase->qname, &qchase->qname_len); if(!qchase->qname) return 0; /* bad CNAME rdata */ (*cname_skip) = i+1; return 1; } } return 0; /* CNAME classified but no matching CNAME ?! */ } /** see if rrset has signer name as one of the rrsig signers */ static int rrset_has_signer(struct ub_packed_rrset_key* rrset, uint8_t* name, size_t len) { struct packed_rrset_data* d = (struct packed_rrset_data*)rrset-> entry.data; size_t i; for(i = d->count; i< d->count+d->rrsig_count; i++) { if(d->rr_len[i] > 2+18+len) { /* at least rdatalen + signature + signame (+1 sig)*/ if(query_dname_compare(name, d->rr_data[i]+2+18) == 0) { return 1; } } } return 0; } void val_fill_reply(struct reply_info* chase, struct reply_info* orig, size_t skip, uint8_t* name, size_t len, uint8_t* signer) { size_t i; int seen_dname = 0; chase->rrset_count = 0; chase->an_numrrsets = 0; chase->ns_numrrsets = 0; chase->ar_numrrsets = 0; /* ANSWER section */ for(i=skip; ian_numrrsets; i++) { if(!signer) { if(query_dname_compare(name, orig->rrsets[i]->rk.dname) == 0) chase->rrsets[chase->an_numrrsets++] = orig->rrsets[i]; } else if(seen_dname && ntohs(orig->rrsets[i]->rk.type) == LDNS_RR_TYPE_CNAME) { chase->rrsets[chase->an_numrrsets++] = orig->rrsets[i]; seen_dname = 0; } else if(rrset_has_signer(orig->rrsets[i], name, len)) { chase->rrsets[chase->an_numrrsets++] = orig->rrsets[i]; if(ntohs(orig->rrsets[i]->rk.type) == LDNS_RR_TYPE_DNAME) { seen_dname = 1; } } } /* AUTHORITY section */ for(i = (skip > orig->an_numrrsets)?skip:orig->an_numrrsets; ian_numrrsets+orig->ns_numrrsets; i++) { if(!signer) { if(query_dname_compare(name, orig->rrsets[i]->rk.dname) == 0) chase->rrsets[chase->an_numrrsets+ chase->ns_numrrsets++] = orig->rrsets[i]; } else if(rrset_has_signer(orig->rrsets[i], name, len)) { chase->rrsets[chase->an_numrrsets+ chase->ns_numrrsets++] = orig->rrsets[i]; } } /* ADDITIONAL section */ for(i= (skip>orig->an_numrrsets+orig->ns_numrrsets)? skip:orig->an_numrrsets+orig->ns_numrrsets; irrset_count; i++) { if(!signer) { if(query_dname_compare(name, orig->rrsets[i]->rk.dname) == 0) chase->rrsets[chase->an_numrrsets +orig->ns_numrrsets+chase->ar_numrrsets++] = orig->rrsets[i]; } else if(rrset_has_signer(orig->rrsets[i], name, len)) { chase->rrsets[chase->an_numrrsets+orig->ns_numrrsets+ chase->ar_numrrsets++] = orig->rrsets[i]; } } chase->rrset_count = chase->an_numrrsets + chase->ns_numrrsets + chase->ar_numrrsets; } void val_check_nonsecure(struct val_env* ve, struct reply_info* rep) { size_t i; /* authority */ for(i=rep->an_numrrsets; ian_numrrsets+rep->ns_numrrsets; i++) { if(((struct packed_rrset_data*)rep->rrsets[i]->entry.data) ->security != sec_status_secure) { /* because we want to return the authentic original * message when presented with CD-flagged queries, * we need to preserve AUTHORITY section data. * However, this rrset is not signed or signed * with the wrong keys. Validation has tried to * verify this rrset with the keysets of import. * But this rrset did not verify. * Therefore the message is bogus. */ log_nametypeclass(VERB_QUERY, "message is bogus, " "non secure rrset", rep->rrsets[i]->rk.dname, ntohs(rep->rrsets[i]->rk.type), ntohs(rep->rrsets[i]->rk.rrset_class)); rep->security = sec_status_bogus; return; } } /* additional */ if(!ve->clean_additional) return; for(i=rep->an_numrrsets+rep->ns_numrrsets; irrset_count; i++) { if(((struct packed_rrset_data*)rep->rrsets[i]->entry.data) ->security != sec_status_secure) { /* This does not cause message invalidation. It was * simply unsigned data in the additional. The * RRSIG must have been truncated off the message. * * However, we do not want to return possible bogus * data to clients that rely on this service for * their authentication. */ /* remove this unneeded additional rrset */ memmove(rep->rrsets+i, rep->rrsets+i+1, sizeof(struct ub_packed_rrset_key*)* (rep->rrset_count - i - 1)); rep->ar_numrrsets--; rep->rrset_count--; i--; } } } void val_mark_indeterminate(struct reply_info* rep, struct val_anchors* anchors, struct rrset_cache* r, struct module_env* env) { size_t i; struct packed_rrset_data* d; for(i=0; irrset_count; i++) { d = (struct packed_rrset_data*)rep->rrsets[i]->entry.data; if(d->security == sec_status_unchecked && !anchors_lookup(anchors, rep->rrsets[i]->rk.dname, rep->rrsets[i]->rk.dname_len, ntohs(rep->rrsets[i]->rk.rrset_class))) { /* mark as indeterminate */ d->security = sec_status_indeterminate; rrset_update_sec_status(r, rep->rrsets[i], *env->now); } } } void val_mark_insecure(struct reply_info* rep, struct key_entry_key* kkey, struct rrset_cache* r, struct module_env* env) { size_t i; struct packed_rrset_data* d; log_assert(key_entry_isnull(kkey)); for(i=0; irrset_count; i++) { d = (struct packed_rrset_data*)rep->rrsets[i]->entry.data; if(d->security == sec_status_unchecked && dname_subdomain_c(rep->rrsets[i]->rk.dname, kkey->name)) { /* mark as insecure */ d->security = sec_status_insecure; rrset_update_sec_status(r, rep->rrsets[i], *env->now); } } } size_t val_next_unchecked(struct reply_info* rep, size_t skip) { size_t i; struct packed_rrset_data* d; for(i=skip+1; irrset_count; i++) { d = (struct packed_rrset_data*)rep->rrsets[i]->entry.data; if(d->security == sec_status_unchecked) { return i; } } return rep->rrset_count; } const char* val_classification_to_string(enum val_classification subtype) { switch(subtype) { case VAL_CLASS_UNTYPED: return "untyped"; case VAL_CLASS_UNKNOWN: return "unknown"; case VAL_CLASS_POSITIVE: return "positive"; case VAL_CLASS_CNAME: return "cname"; case VAL_CLASS_NODATA: return "nodata"; case VAL_CLASS_NAMEERROR: return "nameerror"; case VAL_CLASS_CNAMENOANSWER: return "cnamenoanswer"; case VAL_CLASS_REFERRAL: return "referral"; case VAL_CLASS_ANY: return "qtype_any"; default: return "bad_val_classification"; } }