From: Alessio Podda Date: Thu, 4 Jun 2026 14:46:45 +0000 (+0200) Subject: Reproducer for #5970 acceptance of unvalidated NSEC3 X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=fdecacf07a4384a37574e72ad2258ca454f3b047;p=thirdparty%2Fbind9.git Reproducer for #5970 acceptance of unvalidated NSEC3 Add "dnssec_nsec3" system test. Co-Authored-By: Evan Hunt --- diff --git a/bin/tests/system/dnssec_nsec3/ans1/ans.py b/bin/tests/system/dnssec_nsec3/ans1/ans.py new file mode 100644 index 00000000000..d00855bd71f --- /dev/null +++ b/bin/tests/system/dnssec_nsec3/ans1/ans.py @@ -0,0 +1,19 @@ +#!/usr/bin/python3 + +# Copyright (C) Internet Systems Consortium, Inc. ("ISC") +# +# SPDX-License-Identifier: MPL-2.0 + +from dnssec_nsec3.ans1 import common, f055 +from isctest.asyncserver import AsyncDnsServer + + +def main() -> None: + keys = common.load_keys() + server = AsyncDnsServer(default_aa=True) + server.install_response_handler(f055.F055Handler(keys)) + server.run() + + +if __name__ == "__main__": + main() diff --git a/bin/tests/system/dnssec_nsec3/ans1/common.py b/bin/tests/system/dnssec_nsec3/ans1/common.py new file mode 100644 index 00000000000..6d64495e709 --- /dev/null +++ b/bin/tests/system/dnssec_nsec3/ans1/common.py @@ -0,0 +1,111 @@ +#!/usr/bin/python3 + +# Copyright (C) Internet Systems Consortium, Inc. ("ISC") +# +# SPDX-License-Identifier: MPL-2.0 + +from dataclasses import dataclass +from pathlib import Path + +import json + +from cryptography.hazmat.primitives import serialization + +import dns.dnssec +import dns.flags +import dns.message +import dns.name +import dns.rcode +import dns.rdata +import dns.rdataclass +import dns.rdatatype +import dns.rrset + +from isctest.asyncserver import QueryContext + +TTL = 300 + + +@dataclass(frozen=True) +class Key: + zone: dns.name.Name + private_key: object + dnskey: dns.rdata.Rdata + ds: dns.rdata.Rdata + + +def name(text: str) -> dns.name.Name: + return dns.name.from_text(text) + + +def load_keys() -> dict[str, Key]: + path = Path(".") / "keys.json" + keys = raw_keys = {} + + try: + with path.open(encoding="utf-8") as keys_file: + raw_keys = json.load(keys_file) + except Exception: # pylint: disable=broad-except + pass + + for zone, raw_key in raw_keys.items(): + private_key = serialization.load_pem_private_key( + raw_key["private_pem"].encode("ascii"), + password=None, + ) + dnskey = dns.rdata.from_text( + dns.rdataclass.IN, dns.rdatatype.DNSKEY, raw_key["dnskey"] + ) + ds = dns.rdata.from_text(dns.rdataclass.IN, dns.rdatatype.DS, raw_key["ds"]) + keys[zone] = Key(name(zone), private_key, dnskey, ds) + + return keys + + +def rrset(owner: str, rdtype: dns.rdatatype.RdataType, *rdatas: str) -> dns.rrset.RRset: + return dns.rrset.from_text(owner, TTL, dns.rdataclass.IN, rdtype, *rdatas) + + +def rrset_from_rdata(owner: str, rdata: dns.rdata.Rdata) -> dns.rrset.RRset: + return dns.rrset.from_rdata(owner, TTL, rdata) + + +def add_signed( + section: list[dns.rrset.RRset], covered: dns.rrset.RRset, signer: Key +) -> None: + rrsig = dns.dnssec.sign( + covered, + signer.private_key, + signer.zone, + signer.dnskey, + lifetime=86400, + verify=True, + ) + section.append(covered) + section.append(dns.rrset.from_rdata(covered.name, covered.ttl, rrsig)) + + +def soa_rrset(zone) -> dns.rrset.RRset: + return rrset( + zone, + dns.rdatatype.SOA, + f"ns.{zone} hostmaster.{zone} 1 3600 600 86400 300", + ) + + +def prepare_response(qctx: QueryContext) -> dns.message.Message: + qctx.prepare_new_response(with_zone_data=False) + qctx.response.flags |= dns.flags.AA + qctx.response.set_rcode(dns.rcode.NOERROR) + return qctx.response + + +def nsec3_hash(owner: str) -> str: + return dns.dnssec.nsec3_hash(owner, salt=None, iterations=0, algorithm=1).upper() + + +def nsec3_rrset( + zone: str, owner_hash: str, next_hash: str, flags: int, *types: str +) -> dns.rrset.RRset: + rdata = f"1 {flags} 0 - {next_hash} {' '.join(types)}" + return rrset(f"{owner_hash}.{zone}", dns.rdatatype.NSEC3, rdata) diff --git a/bin/tests/system/dnssec_nsec3/ans1/f055.py b/bin/tests/system/dnssec_nsec3/ans1/f055.py new file mode 100644 index 00000000000..1808ec42339 --- /dev/null +++ b/bin/tests/system/dnssec_nsec3/ans1/f055.py @@ -0,0 +1,217 @@ +#!/usr/bin/python3 + +# Copyright (C) Internet Systems Consortium, Inc. ("ISC") +# +# SPDX-License-Identifier: MPL-2.0 + +from collections.abc import AsyncGenerator +from dataclasses import dataclass +from datetime import datetime, timedelta, timezone + +import base64 + +import dns.dnssec +import dns.message +import dns.rcode +import dns.rdata +import dns.rdataclass +import dns.rdatatype +import dns.rrset + +from dnssec_nsec3.ans1.common import ( + Key, + add_signed, + name, + nsec3_hash, + nsec3_rrset, + prepare_response, + rrset, + rrset_from_rdata, + soa_rrset, +) +from isctest.asyncserver import DnsResponseSend, DomainHandler, QueryContext + +TTL = 300 +F055_ZONE = "f055.test." +SAFE = f"safe.{F055_ZONE}" +CUT = f"cut.{F055_ZONE}" +CONTROL = f"ctl.{F055_ZONE}" +ATTACK = f"a.{CUT}" +CONTROL_ATTACK = f"a.{CONTROL}" +SAFE_A = "198.51.100.55" +FORGED_A = "192.0.2.55" + + +def garbage_rrsig(covered: dns.rrset.RRset, signer: Key) -> dns.rrset.RRset: + now = datetime.now(timezone.utc) + inception = (now - timedelta(hours=1)).strftime("%Y%m%d%H%M%S") + expiration = (now + timedelta(days=1)).strftime("%Y%m%d%H%M%S") + signature = base64.b64encode(bytes(64)).decode("ascii") + labels = len(covered.name.labels) - 1 + text = ( + f"{dns.rdatatype.to_text(covered.rdtype)} " + f"13 {labels} {covered.ttl} {expiration} {inception} " + f"{dns.dnssec.key_id(signer.dnskey)} {F055_ZONE} {signature}" + ) + rdata = dns.rdata.from_text(dns.rdataclass.IN, dns.rdatatype.RRSIG, text) + return dns.rrset.from_rdata(covered.name, covered.ttl, rdata) + + +def base32hex_add(hash_text: str, delta: int) -> str: + raw = bytearray(base64.b32hexdecode(hash_text.upper())) + value = int.from_bytes(raw, "big") + delta + value %= 1 << (8 * len(raw)) + return base64.b32hexencode(value.to_bytes(len(raw), "big")).decode("ascii") + + +def forged_cut_nsec3() -> dns.rrset.RRset: + cut_hash = nsec3_hash(CUT) + return nsec3_rrset( + F055_ZONE, + base32hex_add(cut_hash, -1), + base32hex_add(cut_hash, 1), + 1, + "A", + "RRSIG", + ) + + +@dataclass(frozen=True) +class ChainEntry: + owner: str + owner_hash: str + types: tuple[str, ...] + + +class Nsec3Chain: + def __init__(self) -> None: + entries = [ + (F055_ZONE, ("NS", "SOA", "RRSIG", "DNSKEY", "NSEC3PARAM")), + (SAFE, ("A", "RRSIG")), + (CUT, ("A", "RRSIG")), + (CONTROL, ("A", "RRSIG")), + ] + self.entries = sorted( + (ChainEntry(owner, nsec3_hash(owner), types) for owner, types in entries), + key=lambda entry: entry.owner_hash, + ) + self.by_owner = {entry.owner: entry for entry in self.entries} + + def rrset_for(self, owner: str) -> dns.rrset.RRset: + entry = self.by_owner[owner] + index = self.entries.index(entry) + next_hash = self.entries[(index + 1) % len(self.entries)].owner_hash + return nsec3_rrset(F055_ZONE, entry.owner_hash, next_hash, 0, *entry.types) + + def cover_for(self, owner: str) -> dns.rrset.RRset: + owner_hash = nsec3_hash(owner) + for index, entry in enumerate(self.entries): + next_hash = self.entries[(index + 1) % len(self.entries)].owner_hash + if entry.owner_hash < next_hash: + if entry.owner_hash < owner_hash < next_hash: + return self.rrset_for(entry.owner) + elif owner_hash > entry.owner_hash or owner_hash < next_hash: + return self.rrset_for(entry.owner) + return self.rrset_for(self.entries[-1].owner) + + +def add_signed_nsec3( + section: list[dns.rrset.RRset], + chain: Nsec3Chain, + owner: str, + signer: Key, +) -> None: + add_signed(section, chain.rrset_for(owner), signer) + + +def add_nsec3_nxdomain( + response: dns.message.Message, + chain: Nsec3Chain, + closest: str, + qname: str, + signer: Key, +) -> None: + response.set_rcode(dns.rcode.NXDOMAIN) + add_signed(response.authority, soa_rrset(F055_ZONE), signer) + add_signed_nsec3(response.authority, chain, closest, signer) + add_signed(response.authority, chain.cover_for(qname), signer) + add_signed(response.authority, chain.cover_for(f"*.{closest}"), signer) + + +class F055Handler(DomainHandler): + domains = [F055_ZONE] + + def __init__(self, keys: dict[str, Key]) -> None: + super().__init__() + self.keys = keys + + if F055_ZONE not in keys: + return + + self.zone_key = keys[F055_ZONE] + self.chain = Nsec3Chain() + self.zone = name(F055_ZONE) + self.safe = name(SAFE) + self.cut = name(CUT) + self.control = name(CONTROL) + self.attack = name(ATTACK) + self.control_attack = name(CONTROL_ATTACK) + + async def get_responses( + self, qctx: QueryContext + ) -> AsyncGenerator[DnsResponseSend, None]: + response = prepare_response(qctx) + qname = qctx.qname.to_text() + + if qctx.qname == self.zone and qctx.qtype == dns.rdatatype.DNSKEY: + # Priming, zone DNSKEY + add_signed( + response.answer, + rrset_from_rdata(F055_ZONE, self.zone_key.dnskey), + self.zone_key, + ) + elif qctx.qname == self.zone and qctx.qtype == dns.rdatatype.SOA: + # Priming, zone SOA + add_signed(response.answer, soa_rrset(F055_ZONE), self.zone_key) + elif qctx.qname == self.safe and qctx.qtype == dns.rdatatype.A: + # Safe, good answer + add_signed( + response.answer, rrset(SAFE, dns.rdatatype.A, SAFE_A), self.zone_key + ) + elif qctx.qname == self.cut and qctx.qtype == dns.rdatatype.DS: + # Forged DS answer + forged = forged_cut_nsec3() + response.authority.append(forged) + response.authority.append(garbage_rrsig(forged, self.zone_key)) + add_signed_nsec3(response.authority, self.chain, CUT, self.zone_key) + add_signed(response.authority, soa_rrset(F055_ZONE), self.zone_key) + elif qctx.qname == self.control and qctx.qtype == dns.rdatatype.DS: + # Good DS answer + add_signed_nsec3(response.authority, self.chain, CONTROL, self.zone_key) + add_signed(response.authority, soa_rrset(F055_ZONE), self.zone_key) + elif qctx.qname in {self.attack, self.control_attack}: + # Attack query for CUT/CONTROL + if qctx.qtype == dns.rdatatype.A: + response.answer.append(rrset(qname, dns.rdatatype.A, FORGED_A)) + elif qctx.qtype == dns.rdatatype.DS: + closest = CUT if qctx.qname == self.attack else CONTROL + add_nsec3_nxdomain( + response, + self.chain, + closest, + qname, + self.zone_key, + ) + else: + response.authority.append(soa_rrset(F055_ZONE)) + elif qctx.qname.is_subdomain(self.cut): + # NXDOMAIN the rest + add_nsec3_nxdomain(response, self.chain, CUT, qname, self.zone_key) + elif qctx.qname.is_subdomain(self.control): + # NXDOMAIN the rest + add_nsec3_nxdomain(response, self.chain, CONTROL, qname, self.zone_key) + else: + # NXDOMAIN the rest + add_nsec3_nxdomain(response, self.chain, F055_ZONE, qname, self.zone_key) + + yield DnsResponseSend(response, authoritative=True) diff --git a/bin/tests/system/dnssec_nsec3/ns2/named.conf.j2 b/bin/tests/system/dnssec_nsec3/ns2/named.conf.j2 new file mode 100644 index 00000000000..d8d135ee3ab --- /dev/null +++ b/bin/tests/system/dnssec_nsec3/ns2/named.conf.j2 @@ -0,0 +1,35 @@ +// validating resolver + +options { + query-source address 10.53.0.2; + notify-source 10.53.0.2; + transfer-source 10.53.0.2; + port @PORT@; + pid-file "named.pid"; + listen-on { 10.53.0.2; }; + listen-on-v6 { none; }; + recursion yes; + dnssec-validation yes; + minimal-responses no; + qname-minimization off; +}; + +controls { + inet 10.53.0.2 port @CONTROLPORT@ allow { any; } keys { rndc_key; }; +}; + +include "../../_common/rndc.key"; + +zone "." { + type hint; + file "../../_common/root.hint"; +}; + +zone "f055.test" { + type static-stub; + server-addresses { 10.53.0.1; }; +}; + +trust-anchors { + f055.test. static-key 257 3 13 "@ZONE_DNSKEY@"; +}; diff --git a/bin/tests/system/dnssec_nsec3/tests_dnssec_nsec3_delegation.py b/bin/tests/system/dnssec_nsec3/tests_dnssec_nsec3_delegation.py new file mode 100644 index 00000000000..5d52bc8ae2e --- /dev/null +++ b/bin/tests/system/dnssec_nsec3/tests_dnssec_nsec3_delegation.py @@ -0,0 +1,140 @@ +#!/usr/bin/python3 + +# Copyright (C) Internet Systems Consortium, Inc. ("ISC") +# +# SPDX-License-Identifier: MPL-2.0 + +from pathlib import Path + +import json + +from cryptography.hazmat.primitives import serialization +from cryptography.hazmat.primitives.asymmetric import ec + +import dns.dnssec +import dns.name +import dns.rdataclass +import dns.rdatatype +import pytest + +import isctest +import isctest.mark + +F055_ZONE = "f055.test." +SAFE = f"safe.{F055_ZONE}" +CUT = f"cut.{F055_ZONE}" +CONTROL = f"ctl.{F055_ZONE}" +ATTACK = f"a.{CUT}" +CONTROL_ATTACK = f"a.{CONTROL}" +SAFE_A = "198.51.100.55" +FORGED_A = "192.0.2.55" +AUTH = "10.53.0.1" +RESOLVER = "10.53.0.2" + +pytestmark = [ + isctest.mark.with_ecdsa_deterministic, + pytest.mark.extra_artifacts( + [ + "ans*/ans.run", + "ans*/keys.json", + ] + ), +] + + +def _make_key(zone: str): + private_key = ec.generate_private_key(ec.SECP256R1()) + dnskey = dns.dnssec.make_dnskey( + private_key.public_key(), + algorithm="ECDSAP256SHA256", + flags=257, + ) + ds = dns.dnssec.make_ds(dns.name.from_text(zone), dnskey, "SHA256") + private_pem = private_key.private_bytes( + encoding=serialization.Encoding.PEM, + format=serialization.PrivateFormat.PKCS8, + encryption_algorithm=serialization.NoEncryption(), + ).decode("ascii") + return { + "private_pem": private_pem, + "dnskey": dnskey.to_text(), + "ds": ds.to_text(), + } + + +def bootstrap(): + keys = {F055_ZONE: _make_key(F055_ZONE)} + Path("ans1/keys.json").write_text(json.dumps(keys, indent=2), encoding="ascii") + zone_dnskey = "".join(keys[F055_ZONE]["dnskey"].split()[3:]) + return {"ZONE_DNSKEY": zone_dnskey} + + +def _query(server, qname, qtype): + query = isctest.query.create(qname, qtype) + return isctest.query.tcp(query, server) + + +def _rrset(response, section, owner, rdtype, covers=None): + if covers is None: + return response.get_rrset( + section, + dns.name.from_text(owner), + dns.rdataclass.IN, + rdtype, + ) + return response.get_rrset( + section, + dns.name.from_text(owner), + dns.rdataclass.IN, + rdtype, + covers=covers, + ) + + +def _has_a(response, section, owner, address): + rrset = _rrset(response, section, owner, dns.rdatatype.A) + return rrset is not None and any(rdata.address == address for rdata in rrset) + + +def _has_forged_optout_nsec3(response): + for rrset in response.authority: + if rrset.rdtype != dns.rdatatype.NSEC3: + continue + if rrset[0].flags == 1: + rrsig = _rrset( + response, + response.authority, + rrset.name.to_text(), + dns.rdatatype.RRSIG, + covers=dns.rdatatype.NSEC3, + ) + return rrsig is not None and rrsig[0].signer == dns.name.from_text( + F055_ZONE + ) + return False + + +def test_forged_bogus_inner_nsec3(): + cut_ds = _query(AUTH, CUT, "DS") + isctest.check.noerror(cut_ds) + assert _has_forged_optout_nsec3(cut_ds), cut_ds.to_text() + + +def test_resolver_rejects_bogus_inner_nsec3_downgrade(): + # Baseline (proves the trust anchor and NSEC3 chain validate) + response = _query(RESOLVER, SAFE, "A") + isctest.check.noerror(response) + isctest.check.adflag(response) + assert _has_a(response, response.answer, SAFE, SAFE_A) + + # Control (identical DS NODATA without the forged NSEC3) + response = _query(RESOLVER, CONTROL_ATTACK, "A") + isctest.check.servfail(response) + isctest.check.noadflag(response) + assert not _has_a(response, response.answer, CONTROL_ATTACK, FORGED_A) + + # Attack (DS NODATA carries the forged Opt-Out NSEC3) + response = _query(RESOLVER, ATTACK, "A") + isctest.check.servfail(response) + isctest.check.noadflag(response) + assert not _has_a(response, response.answer, ATTACK, FORGED_A)