From: =?utf-8?b?VmxhZGltw61yIMSMdW7DoXQ=?= Date: Mon, 12 Feb 2024 11:16:47 +0100 Subject: validator: refuse to validate answers with more than 8 NSEC3 records --- lib/layer/validate.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/lib/layer/validate.c b/lib/layer/validate.c index 5fea99d..95a7624 100644 --- a/lib/layer/validate.c +++ b/lib/layer/validate.c @@ -1120,6 +1120,24 @@ static int validate(kr_layer_t *ctx, knot_pkt_t *pkt) } } + /* Check for too many NSEC3 records. That's an issue, as some parts of validation + * are quadratic in their count, doing nontrivial computations inside. + * Also there seems to be no use in sending many NSEC3 records. */ + if (!qry->flags.CACHED) { + const knot_pktsection_t *sec = knot_pkt_section(pkt, KNOT_AUTHORITY); + int count = 0; + for (int i = 0; i < sec->count; ++i) + count += (knot_pkt_rr(sec, i)->type == KNOT_RRTYPE_NSEC3); + if (count > 8) { + VERBOSE_MSG(qry, "<= too many NSEC3 records in AUTHORITY (%d)\n", count); + kr_request_set_extended_error(req, KNOT_EDNS_EDE_NSEC3_ITERS, + /* It's not about iteration values per se, but close enough. */ + "DYRH: too many NSEC3 records"); + qry->flags.DNSSEC_BOGUS = true; + return KR_STATE_FAIL; + } + } + if (knot_wire_get_aa(pkt->wire) && qtype == KNOT_RRTYPE_DNSKEY) { const knot_rrset_t *ds = qry->zone_cut.trust_anchor; if (ds && !kr_ds_algo_support(ds)) {