hyperhive/nix/host-modules/hive-tls.nix
atlas 01680ee962 docs(tls): move the bundle rationale to the CA page
The comment block tripped the 30-line lint, and the lint was right: the
openssl chain-termination explanation had just been written into
docs/swarm/ca.md, so the comment was a second copy of it. What stays is
the part the code cannot say — the inode constraint, why the previous
anchor is not dropped here, and the set -e alternative that was
rejected.
2026-08-05 18:53:51 +02:00

439 lines
20 KiB
Nix

{
lib,
config,
pkgs,
...
}:
let
cfg = config.services.hyperhive.tls;
hyperhiveCfg = config.services.hyperhive;
gatewayCfg = config.services.hyperhive.gateway;
swarmCaCfg = config.services.hyperhive.swarm.ca;
domain = hyperhiveCfg.domain;
# The host-managed hive CA is the trust anchor for self-signed mode.
# It is only stood up when the gateway actually serves a self-signed
# cert: the gateway must be in self-signed mode. `domain` is required
# (asserted in hive-network.nix), so the leaf SANs always have a
# domain to derive from. The self-signed condition is the gateway
# module's single source of truth (`gateway.useSelfSigned`): true when
# neither an operator cert (`tls.certDir`) nor ACME is set.
active = hyperhiveCfg.enable && gatewayCfg.useSelfSigned;
# The leaf-signing action shared by the boot-time `hive-tls-ca`
# generation and the weekly `hive-tls-resign` renewal: fresh key +
# CSR, SAN ext-file, sign under the (stable) CA, tighten modes.
# Takes the TLS state dir as `$1`; each caller keeps its own
# when-to-sign condition. The leaf covers the bare hive domain plus
# `forge.`, `matrix.` and `*.<domain>` so all sub-domains validate
# under the same cert + the hive CA.
# How this hive's CA comes into existence when it is missing — and it
# is one of exactly two things, chosen by config rather than by what
# happens to be on disk.
#
# Issuing a sub-CA requires the swarm root's PRIVATE key, so it can
# only happen where that key legitimately lives: the single-host
# deployment that `swarm.ca.autoConfigure` describes. A host cannot
# infer that it is that host — a swarm's services and its hives can
# sit anywhere — so with the flag off this hive self-signs exactly as
# it always has, and an operator who wants it in the hierarchy
# installs the CA themselves. Falling back to self-signed rather than
# failing keeps a plain hive working out of the box; what it loses is
# membership of a swarm's trust, which is the correct thing to lose
# for a hive nobody has federated.
caGenScript =
if swarmCaCfg.autoConfigure then
''
# The root should exist `swarm-ca.service` runs before this and
# is required by it. If it doesn't, something upstream failed and
# signing with a half-provisioned root would be worse than stopping.
if [ ! -s "$root" ] || [ ! -s "$rootk" ]; then
echo "swarm.ca.autoConfigure is set but there is no root CA key at $rootk" >&2
echo "(swarm-ca.service should have generated it) refusing to issue a hive CA." >&2
exit 1
fi
echo "issuing fresh hive CA at $ca under the swarm root"
cacsr="$(mktemp "$d/ca.csr.XXXXXX")"
caext="$(mktemp "$d/ca.ext.XXXXXX")"
trap 'rm -f "$cacsr" "$caext"' EXIT
openssl req -newkey rsa:4096 -nodes -sha256 \
-keyout "$cak" -out "$cacsr" \
-subj "/CN=hive-ca ${domain}"
# printf (not a heredoc) so the ext-file lines carry no leading
# whitespace once nix has stripped the indented-string indent.
{
printf 'basicConstraints=critical,CA:TRUE,pathlen:0\n'
printf 'keyUsage=critical,keyCertSign,cRLSign\n'
printf 'subjectKeyIdentifier=hash\n'
printf 'authorityKeyIdentifier=keyid:always\n'
# The constraint is the point of the hierarchy, not a
# flourish: without it a leaked hive CA mints any name in
# the swarm, and it is verifiers that enforce this, not our
# good behaviour. The IP exclusions are not redundant a
# DNS constraint says nothing about an iPAddress SAN, and a
# name type nobody constrained is a name type this CA is
# unconstrained for.
printf 'nameConstraints=critical,permitted;DNS:%s,excluded;IP:0.0.0.0/0.0.0.0,excluded;IP:0:0:0:0:0:0:0:0/0:0:0:0:0:0:0:0\n' \
${lib.escapeShellArg domain}
} > "$caext"
openssl x509 -req -in "$cacsr" -CA "$root" -CAkey "$rootk" \
-CAcreateserial -days ${toString cfg.caValidityDays} -sha256 \
-extfile "$caext" -out "$ca"
rm -f "$cacsr" "$caext"
trap - EXIT
''
else
''
echo "generating fresh self-signed hive CA at $ca"
openssl req -x509 -newkey rsa:4096 -nodes -sha256 \
-days ${toString cfg.caValidityDays} \
-keyout "$cak" -out "$ca" \
-subj "/CN=hive-ca ${domain}" \
-addext "basicConstraints=critical,CA:TRUE,pathlen:0" \
-addext "keyUsage=critical,keyCertSign,cRLSign"
'';
signLeafScript = pkgs.writeShellScript "hive-tls-sign-leaf" ''
set -euo pipefail
d="$1"
ca="$d/ca.pem"
cak="$d/ca-key.pem"
leaf="$d/gateway.pem"
leafk="$d/gateway-key.pem"
csr="$(mktemp "$d/gateway.csr.XXXXXX")"
ext="$(mktemp "$d/leaf.ext.XXXXXX")"
only="$(mktemp "$d/gateway.leaf.XXXXXX")"
trap 'rm -f "$csr" "$ext" "$only"' EXIT
openssl req -newkey rsa:4096 -nodes -sha256 \
-keyout "$leafk" -out "$csr" \
-subj "/CN=${domain}"
# printf (not a heredoc) so the ext-file lines carry no leading
# whitespace once nix has stripped the indented-string indent.
{
printf 'subjectAltName=DNS:%s,DNS:forge.%s,DNS:matrix.%s,DNS:*.%s\n' \
${lib.escapeShellArg domain} ${lib.escapeShellArg domain} \
${lib.escapeShellArg domain} ${lib.escapeShellArg domain}
printf 'basicConstraints=critical,CA:FALSE\n'
printf 'keyUsage=critical,digitalSignature,keyEncipherment\n'
printf 'extendedKeyUsage=serverAuth\n'
} > "$ext"
openssl x509 -req -in "$csr" -CA "$ca" -CAkey "$cak" \
-CAcreateserial -days ${toString cfg.leafValidityDays} -sha256 \
-extfile "$ext" -out "$only"
# nginx serves this file verbatim, so it must carry the leaf AND its
# issuer: the hive CA is an intermediate under the swarm root, and a
# client that anchors on the root cannot build the middle of the
# chain by itself. Agents anchor on the hive CA directly and
# validated either way the appended cert is what makes a swarm
# peer, or anything else holding only the root, work.
# Leaf first: both `ssl_certificate` and the `openssl x509 -in`
# expiry checks read the first cert in the file.
cat "$only" "$ca" > "$leaf"
chmod 0600 "$leafk"
chmod 0644 "$leaf"
'';
in
{
# Host-side TLS trust root for the self-signed gateway mode.
#
# A bare self-signed leaf would be its own trust anchor, so every
# regeneration would be a new anchor and every consumer (agents,
# federation peers) would have to re-trust on each rotation — and a
# runtime-generated, in-container cert can't be wired into an agent's
# build-time trust store at all.
#
# So the issuer is a long-lived **hive CA** held on the host. The
# gateway serves a **leaf** signed by that CA (via the `tls.certDir`
# bind-mount path); agents and federation peers trust the *CA* once,
# and leaf rotation never re-breaks them. See `docs/gateway.md`
# ("Self-signed TLS").
#
# That CA is self-signed by default. Under
# `swarm.ca.autoConfigure` — the all-on-one-host case — it is instead
# an intermediate issued under the swarm root (./swarm-ca.nix owns the
# why) and name-constrained to this hive's domain, so it stays the
# anchor agents pin while a peer holding only the root can validate
# everything this hive serves. Either way an existing CA is left
# alone; see the issuance comment below.
options.services.hyperhive.tls = {
stateDir = lib.mkOption {
type = lib.types.str;
default = "/var/lib/hive-tls";
description = ''
Host directory holding the hive CA + gateway leaf cert for the
self-signed gateway mode. `ca.pem` (the anchor agents and
federation peers trust), `ca-key.pem` (0600, never leaves the
host), `gateway.pem` / `gateway-key.pem` (the leaf the gateway
container bind-mounts and nginx serves). Persistent so the CA
survives reboots re-deriving it would re-break every consumer.
'';
};
caValidityDays = lib.mkOption {
type = lib.types.int;
default = 7300;
description = ''
Validity window of the hive CA in days (default ~20y). Kept long
and well beyond `leafValidityDays` so the CA outlives many leaf
rotations the whole point of the CA is to be a stable anchor
that consumers trust once. The CA is regenerated only if missing
or already expired.
'';
};
leafValidityDays = lib.mkOption {
type = lib.types.int;
default = 30;
description = ''
Validity window of the gateway leaf cert in days (default 30).
Short-lived by design ahead of the CA/Browser-Forum's move
toward ~47-day max lifetimes which bounds the blast radius of a
leaf-key compromise. The leaf is re-signed by the (stable) CA
when it is missing or near expiry; because it shares the CA
anchor, a rotation does not disturb consumer trust. Agents and
federation peers validate against the CA, not browser CA/B-forum
limits. The weekly `hive-tls-resign` timer re-signs the leaf once
it is within half its validity of expiry and propagates the new
leaf into the running gateway, so a long-uptime host renews
automatically without a reboot.
'';
};
};
config = lib.mkIf active {
# Generate (and rotate) the hive CA + gateway leaf before the gateway
# container starts. Idempotent: the CA is created once and reused; the
# leaf is re-signed on expiry under the same CA so the anchor is stable.
systemd.services.hive-tls-ca = {
description = "Generate hive CA + gateway leaf TLS cert (self-signed mode)";
wantedBy = [ "multi-user.target" ];
# Gateway nginx reads the leaf from the bind-mount, so the cert must
# exist before the container starts. Declarative nixos-containers are
# instances of the `container@.service` template.
before = [ "container@hive-gateway.service" ];
requiredBy = [ "container@hive-gateway.service" ];
# The issuance below needs the swarm root key on disk. When this
# host generates it (single-host swarm) that unit must have run;
# when the operator provides it there is no unit to wait for, so
# the dependency is conditional rather than a unit that exists and
# does nothing.
after = lib.optional swarmCaCfg.autoConfigure "swarm-ca.service";
requires = lib.optional swarmCaCfg.autoConfigure "swarm-ca.service";
path = [ pkgs.openssl ];
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
UMask = "0077";
# Pin the journal identity (else it's the `script` store-path wrapper).
SyslogIdentifier = "hive-tls-ca";
};
script = ''
set -euo pipefail
d=${lib.escapeShellArg cfg.stateDir}
install -d -m 0755 "$d"
ca="$d/ca.pem"
cak="$d/ca-key.pem"
leaf="$d/gateway.pem"
leafk="$d/gateway-key.pem"
root=${lib.escapeShellArg "${swarmCaCfg.stateDir}/root.pem"}
rootk=${lib.escapeShellArg "${swarmCaCfg.stateDir}/root-key.pem"}
prev="$d/ca-previous.pem"
marker="$d/.swarm-ca-adopted"
# --- Adoption: a hive whose CA predates the swarm root.
#
# Runs ONLY where this host also owns the root (`autoConfigure`),
# because adoption invalidates an anchor that consumers already
# trust and they refresh on their own schedule. On one box that
# schedule is knowable; across hosts it is not, so there the
# operator does it and this unit only says so, loudly.
#
# Guarded by a marker rather than by the state of the world: the
# marker's ABSENCE is the trigger, so this fires once per hive
# instead of re-deciding every activation. That is the difference
# between a migration and a kicking machine.
if [ -s "$root" ] && [ -s "$ca" ] && [ ! -e "$marker" ] \
&& ! openssl verify -CAfile "$root" "$ca" >/dev/null 2>&1; then
${
if swarmCaCfg.autoConfigure then
''
echo "adopting the swarm CA: $ca does not chain to $root" >&2
# Keep the old CA as an anchor across the overlap. Consumers
# read the bundle, so adoption is additive before it is
# subtractive agents pick up new trust only when their
# container restarts, which is a window even on one host.
cp "$ca" "$prev"
chmod 0644 "$prev"
rm -f "$ca" "$cak"
touch "$marker"''
else
''
echo "hive-tls: this hive's CA does not chain to the swarm root." >&2
echo " hive CA: $ca" >&2
echo " swarm root: $root" >&2
echo "Adopting the hierarchy is not automatic here: it invalidates an" >&2
echo "anchor that peers and agents on OTHER hosts still trust, and they" >&2
echo "refresh on their own schedule only you know when that is safe." >&2
echo "To adopt: rm $ca $cak && systemctl restart hive-tls-ca.service" >&2
echo "To keep the current CA deliberately: touch $marker" >&2
exit 1''
}
fi
# --- CA: generated once and reused across leaf rotations, in
# whichever of the two shapes `caGenScript` selected.
# Regenerated only if missing or already expired (checkend 0).
# A new CA means every consumer must re-trust, so the leaf is
# dropped to force a re-sign under the fresh CA.
#
# An existing CA is never re-rooted here. A hive predating the
# swarm root carries a self-signed `ca.pem`, and swapping it for
# a swarm-issued one would break every consumer already trusting
# it including agents, whose trust is refreshed only when their
# container restarts. Adopting the hierarchy on such a hive is
# therefore an operator step (drop the CA, let this unit
# re-issue), which is also what keeps this change non-disruptive
# to hives that never adopt it.
if [ ! -s "$ca" ] || [ ! -s "$cak" ] \
|| ! openssl x509 -in "$ca" -noout -checkend 0 >/dev/null 2>&1; then
${caGenScript}
chmod 0600 "$cak"
chmod 0644 "$ca"
rm -f "$leaf" "$leafk"
fi
# --- Leaf: (re)sign when missing or within 30 days of expiry,
# always under the current (stable) CA.
if [ ! -s "$leaf" ] || [ ! -s "$leafk" ] \
|| ! openssl x509 -in "$leaf" -noout -checkend 2592000 >/dev/null 2>&1; then
echo "signing fresh gateway leaf at $leaf"
${signLeafScript} "$d"
fi
# --- Trust bundle: what a consumer must TRUST, as opposed to
# `ca.pem`, which is what this host SIGNS with. Why they stopped
# being the same file, and why `ca-previous.pem` stays in the set
# after an adoption, are in docs/swarm/ca.md. Three constraints
# the code cannot state:
#
# Written IN PLACE, never renamed into position containers
# bind-mount this file and a bind mount follows the inode, so a
# rename leaves every consumer holding the old one.
#
# Dropping `ca-previous.pem` is deliberately NOT done here:
# "long enough" is a deployment fact, not a unit's call.
#
# Built as an array with `if` guards, not
# `[ -s f ] && anchors+=(f)`: under `set -e` an && list whose test
# fails IS a failing command and kills the unit on exactly the
# hive where the optional file is legitimately absent. The
# reflexive `|| true` is worse; it also swallows a real failure to
# read the hive CA.
bundle="$d/trust-bundle.pem"
anchors=("$ca")
if [ -s "$prev" ]; then anchors+=("$prev"); fi
if [ -s "$root" ]; then anchors+=("$root"); fi
cat "''${anchors[@]}" > "$bundle"
chmod 0644 "$bundle"
'';
};
# Weekly re-sign of the gateway leaf so short-lived leaves renew
# without depending on a reboot.
#
# `hive-tls-ca` only re-signs at service activation (boot/rebuild); a
# long-uptime host would otherwise let a 30-day leaf lapse silently.
# This service re-signs the leaf directly (not by bouncing hive-tls-ca)
# and propagates the new leaf into the running gateway container when
# the file actually changed.
#
# Propagation mechanism: nginx in the gateway container serves a *copy*
# of the leaf written by `hive-gateway-self-signed-cert` (which runs at
# container start). A host-side `systemctl -M hive-gateway` call
# triggers the re-import + reload, mirroring how hive-c0re reloads the
# gateway after each agents.conf write. A path unit *inside* the
# container cannot do this: IN_MOVED_TO from an atomic rename on the
# host does not propagate across the nspawn mount-namespace boundary.
#
# `|| true` on propagation so a stopped gateway never fails the unit —
# its next boot will import the already-rotated leaf anyway.
systemd.services.hive-tls-resign = {
description = "Re-sign the gateway TLS leaf and propagate it into the gateway container";
# hive-tls-ca must have run first so the CA key exists before we try
# to re-sign under it. On first boot `Persistent=true` on the weekly
# timer fires immediately; without this ordering the resign could race
# the CA initialisation and fail with "no such file" on the CA key.
after = [ "hive-tls-ca.service" ];
path = [
pkgs.openssl
pkgs.coreutils
pkgs.systemd
];
serviceConfig = {
Type = "oneshot";
UMask = "0077";
SyslogIdentifier = "hive-tls-resign";
};
script = ''
set -euo pipefail
d=${lib.escapeShellArg cfg.stateDir}
leaf="$d/gateway.pem"
# Re-sign only when the leaf is within half its validity of expiry.
# The weekly cadence catches this window well before the leaf lapses.
halflife=$(( ${toString cfg.leafValidityDays} * 86400 / 2 ))
if [ -s "$leaf" ] && \
openssl x509 -in "$leaf" -noout -checkend "$halflife" >/dev/null 2>&1; then
echo "gateway leaf valid for more than half its lifetime no resign needed"
exit 0
fi
echo "gateway leaf missing or near expiry re-signing under current CA"
before="$(sha256sum "$leaf" 2>/dev/null || true)"
${signLeafScript} "$d"
after="$(sha256sum "$leaf" 2>/dev/null || true)"
if [ "$before" != "$after" ]; then
echo "gateway leaf rotated propagating into hive-gateway"
systemctl -M hive-gateway restart hive-gateway-self-signed-cert.service || true
systemctl -M hive-gateway reload nginx.service || true
else
echo "gateway leaf unchanged (already up to date)"
fi
'';
};
systemd.timers.hive-tls-resign = {
description = "Weekly gateway-leaf re-sign and propagation";
wantedBy = [ "timers.target" ];
timerConfig = {
# Run weekly; Persistent=true fires a missed run on next boot if
# the timer was not active (e.g. the host was off on the scheduled
# day), preventing a dormant timer from letting the leaf lapse.
OnCalendar = "weekly";
Persistent = true;
};
};
# Signal the hive-c0re lifecycle that a hive CA exists: it bind-mounts
# this file (read-only, public certs ONLY — never a key) into each
# agent container so agents + their tools can trust the gateway's
# self-signed leaf, and the meta flake wires the per-agent trust
# bundle. It is the ANCHOR bundle rather than `ca.pem` for the reason
# spelled out where the bundle is written above; no key path is ever
# exposed (an agent that could read one could mint trusted certs).
systemd.services.hive-c0re.environment.HIVE_TLS_CA_PATH = "${cfg.stateDir}/trust-bundle.pem";
};
}