set up DS records and trust anchor to make DNSSEC work

This commit is contained in:
Jorge Aparicio 2024-02-07 20:11:09 +01:00
parent 2bcad2a25c
commit 306ce7a32b
6 changed files with 398 additions and 95 deletions

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@ -2,5 +2,3 @@ FROM ubuntu:22.04
RUN apt-get update && \
apt-get install -y dnsutils unbound nsd iputils-ping tshark vim ldnsutils
COPY ./files/etc/unbound/unbound.conf /etc/unbound/unbound.conf

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@ -16,6 +16,22 @@ impl Client {
})
}
// FIXME this needs to use the same trust anchor as `RecursiveResolver` or validation will fail
pub fn delv(
&self,
server: Ipv4Addr,
record_type: RecordType,
fqdn: &FQDN<'_>,
) -> Result<String> {
self.inner.stdout(&[
"delv",
"+mtrace",
&format!("@{server}"),
record_type.as_str(),
fqdn.as_str(),
])
}
pub fn dig(
&self,
recurse: Recurse,
@ -153,6 +169,7 @@ pub struct DigFlags {
pub recursion_desired: bool,
pub recursion_available: bool,
pub authoritative_answer: bool,
pub authenticated_data: bool,
}
impl FromStr for DigFlags {
@ -163,6 +180,7 @@ impl FromStr for DigFlags {
let mut recursion_desired = false;
let mut recursion_available = false;
let mut authoritative_answer = false;
let mut authenticated_data = false;
for flag in input.split_whitespace() {
match flag {
@ -170,6 +188,7 @@ impl FromStr for DigFlags {
"rd" => recursion_desired = true,
"ra" => recursion_available = true,
"aa" => authoritative_answer = true,
"ad" => authenticated_data = true,
_ => return Err(format!("unknown flag: {flag}").into()),
}
}
@ -179,6 +198,7 @@ impl FromStr for DigFlags {
recursion_desired,
recursion_available,
authoritative_answer,
authenticated_data,
})
}
}

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@ -1,12 +1,10 @@
use core::array;
use core::str::FromStr;
use core::sync::atomic::{self, AtomicUsize};
use std::net::Ipv4Addr;
use std::process::Child;
use crate::container::Container;
use crate::zone_file::{self, SoaSettings, ZoneFile};
use crate::{Error, Result, FQDN};
use crate::zone_file::{self, SoaSettings, ZoneFile, DNSKEY, DS};
use crate::{Result, FQDN};
pub struct NameServer<'a, State> {
container: Container,
@ -68,6 +66,12 @@ impl<'a> NameServer<'a, Stopped> {
self
}
/// Adds a DS record to the zone file
pub fn ds(&mut self, ds: DS) -> &mut Self {
self.zone_file.entry(ds);
self
}
/// Freezes and signs the name server's zone file
pub fn sign(self) -> Result<NameServer<'a, Signed>> {
// TODO do we want to make these settings configurable?
@ -90,13 +94,13 @@ impl<'a> NameServer<'a, Stopped> {
format!("cd {ZONES_DIR} && ldns-keygen -a {ALGORITHM} -b {ZSK_BITS} {zone}");
let zsk_filename = container.stdout(&["sh", "-c", &zsk_keygen])?;
let zsk_path = format!("{ZONES_DIR}/{zsk_filename}.key");
let zsk: Key = container.stdout(&["cat", &zsk_path])?.parse()?;
let zsk: DNSKEY = container.stdout(&["cat", &zsk_path])?.parse()?;
let ksk_keygen =
format!("cd {ZONES_DIR} && ldns-keygen -k -a {ALGORITHM} -b {KSK_BITS} {zone}");
let ksk_filename = container.stdout(&["sh", "-c", &ksk_keygen])?;
let ksk_path = format!("{ZONES_DIR}/{ksk_filename}.key");
let ksk: Key = container.stdout(&["cat", &ksk_path])?.parse()?;
let ksk: DNSKEY = container.stdout(&["cat", &ksk_path])?.parse()?;
// -n = use NSEC3 instead of NSEC
// -p = set the opt-out flag on all nsec3 rrs
@ -105,6 +109,11 @@ impl<'a> NameServer<'a, Stopped> {
);
container.status_ok(&["sh", "-c", &signzone])?;
// TODO do we want to make the hashing algorithm configurable?
// -2 = use SHA256 for the DS hash
let key2ds = format!("cd {ZONES_DIR} && ldns-key2ds -n -2 {ZONE_FILENAME}.signed");
let ds: DS = container.stdout(&["sh", "-c", &key2ds])?.parse()?;
// we have an in-memory representation of the zone file so we just delete the on-disk version
let zone_file_path = zone_file_path();
container.status_ok(&["mv", &format!("{zone_file_path}.signed"), &zone_file_path])?;
@ -115,9 +124,10 @@ impl<'a> NameServer<'a, Stopped> {
container,
zone_file,
state: Signed {
zsk,
ds,
ksk,
signed_zone_file,
zsk,
},
})
}
@ -148,62 +158,6 @@ impl<'a> NameServer<'a, Stopped> {
}
}
#[derive(Debug)]
pub struct Key {
pub bits: u16,
pub encoded: String,
pub id: u32,
}
impl FromStr for Key {
type Err = Error;
fn from_str(input: &str) -> Result<Self> {
let (before, after) = input.split_once(';').ok_or("comment was not found")?;
let mut columns = before.split_whitespace();
let [Some(_zone), Some(class), Some(record_type), Some(_flags), Some(_protocol), Some(_algorithm), Some(encoded), None] =
array::from_fn(|_| columns.next())
else {
return Err("expected 7 columns".into());
};
if record_type != "DNSKEY" {
return Err(format!("tried to parse `{record_type}` record as a DNSKEY record").into());
}
if class != "IN" {
return Err(format!("unknown class: {class}").into());
}
// {id = 24975 (zsk), size = 1024b}
let error = "invalid comment syntax";
let (id_expr, size_expr) = after.split_once(',').ok_or(error)?;
// {id = 24975 (zsk)
let (id_lhs, id_rhs) = id_expr.split_once('=').ok_or(error)?;
if id_lhs.trim() != "{id" {
return Err(error.into());
}
// 24975 (zsk)
let (id, _key_type) = id_rhs.trim().split_once(' ').ok_or(error)?;
// size = 1024b}
let (size_lhs, size_rhs) = size_expr.split_once('=').ok_or(error)?;
if size_lhs.trim() != "size" {
return Err(error.into());
}
let bits = size_rhs.trim().strip_suffix("b}").ok_or(error)?.parse()?;
Ok(Self {
bits,
encoded: encoded.to_string(),
id: id.parse()?,
})
}
}
const ZONES_DIR: &str = "/etc/nsd/zones";
const ZONE_FILENAME: &str = "main.zone";
@ -239,17 +193,21 @@ impl<'a> NameServer<'a, Signed> {
})
}
pub fn key_signing_key(&self) -> &Key {
pub fn key_signing_key(&self) -> &DNSKEY {
&self.state.ksk
}
pub fn zone_signing_key(&self) -> &Key {
pub fn zone_signing_key(&self) -> &DNSKEY {
&self.state.zsk
}
pub fn signed_zone_file(&self) -> &str {
&self.state.signed_zone_file
}
pub fn ds(&self) -> &DS {
&self.state.ds
}
}
impl<'a, S> NameServer<'a, S> {
@ -257,6 +215,7 @@ impl<'a, S> NameServer<'a, S> {
self.container.ipv4_addr()
}
/// Zone file BEFORE signing
pub fn zone_file(&self) -> &ZoneFile<'a> {
&self.zone_file
}
@ -273,8 +232,9 @@ impl<'a, S> NameServer<'a, S> {
pub struct Stopped;
pub struct Signed {
zsk: Key,
ksk: Key,
ds: DS,
zsk: DNSKEY,
ksk: DNSKEY,
signed_zone_file: String,
}
@ -360,21 +320,21 @@ mod tests {
#[test]
fn signed() -> Result<()> {
let tld_ns = NameServer::new(FQDN::ROOT)?.sign()?;
let ns = NameServer::new(FQDN::ROOT)?.sign()?;
eprintln!("KSK: {:?}", tld_ns.key_signing_key());
eprintln!("ZSK: {:?}", tld_ns.zone_signing_key());
eprintln!("root.zone.signed:\n{}", tld_ns.signed_zone_file());
eprintln!("KSK:\n{}", ns.key_signing_key());
eprintln!("ZSK:\n{}", ns.zone_signing_key());
eprintln!("root.zone.signed:\n{}", ns.signed_zone_file());
let tld_ns = tld_ns.start()?;
let tld_ns = ns.start()?;
let ipv4_addr = tld_ns.ipv4_addr();
let ns_addr = tld_ns.ipv4_addr();
let client = Client::new()?;
let output = client.dig(
Recurse::No,
Dnssec::Yes,
ipv4_addr,
ns_addr,
RecordType::SOA,
&FQDN::ROOT,
)?;
@ -392,18 +352,4 @@ mod tests {
Ok(())
}
#[test]
fn can_parse_ldns_keygen_output() -> Result<()> {
let input = "example.com. IN DNSKEY 256 3 7 AwEAAdIpMlio4GJas7GbIZ9xRpzpB2pf4SxBJcsquN/0yNBPGNE2rzcFykqMAKmLwypk1/1q/EdHVa4tQ5RlK0w09CRhgSXfCaph+yLNJKpiPyuVcXKl2k0RnO4p835sgVEUIvx8qGTDo7c7DA9UBje+/3ViFKqVhOBaWyT6gHAmNVpb ;{id = 24975 (zsk), size = 1024b}";
let key: Key = input.parse()?;
assert_eq!(1024, key.bits);
assert_eq!(24975, key.id);
let expected = "AwEAAdIpMlio4GJas7GbIZ9xRpzpB2pf4SxBJcsquN/0yNBPGNE2rzcFykqMAKmLwypk1/1q/EdHVa4tQ5RlK0w09CRhgSXfCaph+yLNJKpiPyuVcXKl2k0RnO4p835sgVEUIvx8qGTDo7c7DA9UBje+/3ViFKqVhOBaWyT6gHAmNVpb";
assert_eq!(expected, key.encoded);
Ok(())
}
}

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@ -3,7 +3,7 @@ use std::net::Ipv4Addr;
use std::process::Child;
use crate::container::Container;
use crate::zone_file::Root;
use crate::zone_file::{Root, DNSKEY};
use crate::Result;
pub struct RecursiveResolver {
@ -12,7 +12,9 @@ pub struct RecursiveResolver {
}
impl RecursiveResolver {
pub fn start(roots: &[Root]) -> Result<Self> {
pub fn start(roots: &[Root], trust_anchors: &[DNSKEY]) -> Result<Self> {
const TRUST_ANCHOR_FILE: &str = "/etc/trusted-key.key";
let container = Container::run()?;
let mut hints = String::new();
@ -22,6 +24,18 @@ impl RecursiveResolver {
container.cp("/etc/unbound/root.hints", &hints)?;
let use_dnssec = !trust_anchors.is_empty();
container.cp("/etc/unbound/unbound.conf", &unbound_conf(use_dnssec))?;
if use_dnssec {
let trust_anchor = trust_anchors.iter().fold(String::new(), |mut buf, ds| {
writeln!(buf, "{ds}").expect("infallible");
buf
});
container.cp(TRUST_ANCHOR_FILE, &trust_anchor)?;
}
let child = container.spawn(&["unbound", "-d"])?;
Ok(Self { child, container })
@ -38,8 +52,13 @@ impl Drop for RecursiveResolver {
}
}
fn unbound_conf(use_dnssec: bool) -> String {
minijinja::render!(include_str!("templates/unbound.conf.jinja"), use_dnssec => use_dnssec)
}
#[cfg(test)]
mod tests {
use crate::{
client::{Client, Dnssec, Recurse},
name_server::NameServer,
@ -81,7 +100,7 @@ mod tests {
eprintln!("root.zone:\n{}", root_ns.zone_file());
let roots = &[Root::new(root_ns.fqdn().clone(), root_ns.ipv4_addr())];
let resolver = RecursiveResolver::start(roots)?;
let resolver = RecursiveResolver::start(roots, &[])?;
let resolver_ip_addr = resolver.ipv4_addr();
let client = Client::new()?;
@ -103,4 +122,115 @@ mod tests {
Ok(())
}
// no DS records are involved; this is a single-link chain of trust
#[test]
fn can_validate_without_delegation() -> Result<()> {
let mut ns = NameServer::new(FQDN::ROOT)?;
ns.a(ns.fqdn().clone(), ns.ipv4_addr());
let ns = ns.sign()?;
let root_ksk = ns.key_signing_key().clone();
let root_zsk = ns.zone_signing_key().clone();
eprintln!("root.zone.signed:\n{}", ns.signed_zone_file());
let ns = ns.start()?;
eprintln!("root.zone:\n{}", ns.zone_file());
let roots = &[Root::new(ns.fqdn().clone(), ns.ipv4_addr())];
let trust_anchor = [root_ksk.clone(), root_zsk.clone()];
let resolver = RecursiveResolver::start(roots, &trust_anchor)?;
let resolver_addr = resolver.ipv4_addr();
let client = Client::new()?;
let output = client.dig(
Recurse::Yes,
Dnssec::Yes,
resolver_addr,
RecordType::SOA,
&FQDN::ROOT,
)?;
assert!(output.status.is_noerror());
assert!(output.flags.authenticated_data);
Ok(())
}
#[test]
fn can_validate_with_delegation() -> Result<()> {
let expected_ipv4_addr = Ipv4Addr::new(1, 2, 3, 4);
let needle = FQDN("example.nameservers.com.")?;
let mut root_ns = NameServer::new(FQDN::ROOT)?;
let mut com_ns = NameServer::new(FQDN::COM)?;
let mut nameservers_ns = NameServer::new(FQDN("nameservers.com.")?)?;
nameservers_ns
.a(root_ns.fqdn().clone(), root_ns.ipv4_addr())
.a(com_ns.fqdn().clone(), com_ns.ipv4_addr())
.a(needle.clone(), expected_ipv4_addr);
let nameservers_ns = nameservers_ns.sign()?;
let nameservers_ds = nameservers_ns.ds().clone();
let nameservers_ns = nameservers_ns.start()?;
eprintln!("nameservers.com.zone:\n{}", nameservers_ns.zone_file());
com_ns
.referral(
nameservers_ns.zone().clone(),
nameservers_ns.fqdn().clone(),
nameservers_ns.ipv4_addr(),
)
.ds(nameservers_ds);
let com_ns = com_ns.sign()?;
let com_ds = com_ns.ds().clone();
let com_ns = com_ns.start()?;
eprintln!("com.zone:\n{}", com_ns.zone_file());
root_ns
.referral(FQDN::COM, com_ns.fqdn().clone(), com_ns.ipv4_addr())
.ds(com_ds);
let root_ns = root_ns.sign()?;
let root_ksk = root_ns.key_signing_key().clone();
let root_zsk = root_ns.zone_signing_key().clone();
eprintln!("root.zone.signed:\n{}", root_ns.signed_zone_file());
let root_ns = root_ns.start()?;
eprintln!("root.zone:\n{}", root_ns.zone_file());
let roots = &[Root::new(root_ns.fqdn().clone(), root_ns.ipv4_addr())];
let resolver = RecursiveResolver::start(roots, &[root_ksk.clone(), root_zsk.clone()])?;
let resolver_ip_addr = resolver.ipv4_addr();
let client = Client::new()?;
let output = client.dig(
Recurse::Yes,
Dnssec::Yes,
resolver_ip_addr,
RecordType::A,
&needle,
)?;
drop(resolver);
assert!(output.status.is_noerror());
assert!(output.flags.authenticated_data);
let [a, _rrsig] = output.answer.try_into().unwrap();
let a = a.try_into_a().unwrap();
assert_eq!(needle, a.fqdn);
assert_eq!(expected_ipv4_addr, a.ipv4_addr);
Ok(())
}
}

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@ -4,6 +4,9 @@ server:
interface: 0.0.0.0
access-control: 172.17.0.0/16 allow
root-hints: /etc/unbound/root.hints
{% if use_dnssec %}
trust-anchor-file: /etc/trusted-key.key
{% endif %}
remote-control:
control-enable: no

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@ -4,10 +4,11 @@
//! - the `@` syntax is not used to avoid relying on the order of the entries
//! - relative domain names are not used; all domain names must be in fully-qualified form
use core::fmt;
use core::{array, fmt};
use std::net::Ipv4Addr;
use std::str::FromStr;
use crate::FQDN;
use crate::{Error, FQDN};
pub struct ZoneFile<'a> {
pub origin: FQDN<'a>,
@ -94,9 +95,17 @@ impl fmt::Display for Root<'_> {
pub enum Entry<'a> {
A(A<'a>),
DNSKEY(DNSKEY),
DS(DS),
NS(NS<'a>),
}
impl<'a> From<DS> for Entry<'a> {
fn from(v: DS) -> Self {
Self::DS(v)
}
}
impl<'a> From<A<'a>> for Entry<'a> {
fn from(v: A<'a>) -> Self {
Self::A(v)
@ -113,6 +122,8 @@ impl fmt::Display for Entry<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Entry::A(a) => a.fmt(f),
Entry::DNSKEY(dnskey) => dnskey.fmt(f),
Entry::DS(ds) => ds.fmt(f),
Entry::NS(ns) => ns.fmt(f),
}
}
@ -132,6 +143,166 @@ impl fmt::Display for A<'_> {
}
}
// integer types chosen based on bit sizes in section 2.1 of RFC4034
#[derive(Clone, Debug)]
pub struct DNSKEY {
zone: FQDN<'static>,
flags: u16,
protocol: u8,
algorithm: u8,
public_key: String,
// extra information in `+multiline` format and `ldns-keygen`'s output
bits: u16,
key_tag: u16,
}
impl DNSKEY {
pub fn bits(&self) -> u16 {
self.bits
}
pub fn key_tag(&self) -> u16 {
self.key_tag
}
}
impl FromStr for DNSKEY {
type Err = Error;
fn from_str(input: &str) -> Result<Self, Self::Err> {
let (before, after) = input.split_once(';').ok_or("comment was not found")?;
let mut columns = before.split_whitespace();
let [Some(zone), Some(class), Some(record_type), Some(flags), Some(protocol), Some(algorithm), Some(public_key), None] =
array::from_fn(|_| columns.next())
else {
return Err("expected 7 columns".into());
};
if record_type != "DNSKEY" {
return Err(format!("tried to parse `{record_type}` record as a DNSKEY record").into());
}
if class != "IN" {
return Err(format!("unknown class: {class}").into());
}
// {id = 24975 (zsk), size = 1024b}
let error = "invalid comment syntax";
let (id_expr, size_expr) = after.split_once(',').ok_or(error)?;
// {id = 24975 (zsk)
let (id_lhs, id_rhs) = id_expr.split_once('=').ok_or(error)?;
if id_lhs.trim() != "{id" {
return Err(error.into());
}
// 24975 (zsk)
let (key_tag, _key_type) = id_rhs.trim().split_once(' ').ok_or(error)?;
// size = 1024b}
let (size_lhs, size_rhs) = size_expr.split_once('=').ok_or(error)?;
if size_lhs.trim() != "size" {
return Err(error.into());
}
let bits = size_rhs.trim().strip_suffix("b}").ok_or(error)?.parse()?;
Ok(Self {
zone: zone.parse()?,
flags: flags.parse()?,
protocol: protocol.parse()?,
algorithm: algorithm.parse()?,
public_key: public_key.to_string(),
key_tag: key_tag.parse()?,
bits,
})
}
}
impl fmt::Display for DNSKEY {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let Self {
zone,
flags,
protocol,
algorithm,
public_key,
bits: _,
key_tag: _,
} = self;
write!(
f,
"{zone}\tIN\tDNSKEY\t{flags}\t{protocol}\t{algorithm}\t{public_key}"
)
}
}
#[derive(Clone)]
pub struct DS {
zone: FQDN<'static>,
_ttl: u32,
key_tag: u16,
algorithm: u8,
digest_type: u8,
digest: String,
}
impl FromStr for DS {
type Err = Error;
fn from_str(input: &str) -> Result<Self, Self::Err> {
let mut columns = input.split_whitespace();
let [Some(zone), Some(ttl), Some(class), Some(record_type), Some(key_tag), Some(algorithm), Some(digest_type), Some(digest), None] =
array::from_fn(|_| columns.next())
else {
return Err("expected 8 columns".into());
};
let expected = "DS";
if record_type != expected {
return Err(
format!("tried to parse `{record_type}` entry as a {expected} entry").into(),
);
}
if class != "IN" {
return Err(format!("unknown class: {class}").into());
}
Ok(Self {
zone: zone.parse()?,
_ttl: ttl.parse()?,
key_tag: key_tag.parse()?,
algorithm: algorithm.parse()?,
digest_type: digest_type.parse()?,
digest: digest.to_string(),
})
}
}
/// NOTE does NOT include the TTL field
impl fmt::Display for DS {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let Self {
zone,
_ttl,
key_tag,
algorithm,
digest_type,
digest,
} = self;
write!(
f,
"{zone}\tIN\tDS\t{key_tag}\t{algorithm}\t{digest_type}\t{digest}"
)
}
}
pub struct NS<'a> {
pub zone: FQDN<'a>,
pub nameserver: FQDN<'a>,
@ -262,6 +433,41 @@ e.gtld-servers.net. IN A 192.12.94.30
Ok(())
}
// not quite roundtrip because we drop the TTL field when doing `to_string`
#[test]
fn ds_roundtrip() -> Result<()> {
let input =
". 1800 IN DS 31153 7 2 7846338aaacde9cc9518f1f450082adc015a207c45a1e69d6e660e6836f4ef3b";
let ds: DS = input.parse()?;
let output = ds.to_string();
let expected =
". IN DS 31153 7 2 7846338aaacde9cc9518f1f450082adc015a207c45a1e69d6e660e6836f4ef3b";
assert_eq!(expected, output);
Ok(())
}
#[test]
fn dnskey_roundtrip() -> Result<()> {
let input = "example.com. IN DNSKEY 256 3 7 AwEAAdIpMlio4GJas7GbIZ9xRpzpB2pf4SxBJcsquN/0yNBPGNE2rzcFykqMAKmLwypk1/1q/EdHVa4tQ5RlK0w09CRhgSXfCaph+yLNJKpiPyuVcXKl2k0RnO4p835sgVEUIvx8qGTDo7c7DA9UBje+/3ViFKqVhOBaWyT6gHAmNVpb ;{id = 24975 (zsk), size = 1024b}";
let dnskey: DNSKEY = input.parse()?;
assert_eq!(256, dnskey.flags);
assert_eq!(3, dnskey.protocol);
assert_eq!(7, dnskey.algorithm);
let expected = "AwEAAdIpMlio4GJas7GbIZ9xRpzpB2pf4SxBJcsquN/0yNBPGNE2rzcFykqMAKmLwypk1/1q/EdHVa4tQ5RlK0w09CRhgSXfCaph+yLNJKpiPyuVcXKl2k0RnO4p835sgVEUIvx8qGTDo7c7DA9UBje+/3ViFKqVhOBaWyT6gHAmNVpb";
assert_eq!(expected, dnskey.public_key);
assert_eq!(1024, dnskey.bits());
assert_eq!(24975, dnskey.key_tag());
let output = dnskey.to_string();
assert!(input.starts_with(&output));
Ok(())
}
fn example_a() -> Result<A<'static>> {
Ok(A {
fqdn: FQDN("e.gtld-servers.net.")?,