From 6e8e2bf5083a268a278af5e331d2f0b3f262d157 Mon Sep 17 00:00:00 2001
From: Juan Font Alonso <juanfontalonso@gmail.com>
Date: Sat, 13 Aug 2022 11:14:38 +0200
Subject: [PATCH] Generate and read the Noise private key

---
 app.go              | 27 +++++++++++++++++++--------
 config-example.yaml |  7 +++++++
 config.go           |  4 ++++
 3 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/app.go b/app.go
index 3e00120..8cfaa61 100644
--- a/app.go
+++ b/app.go
@@ -72,12 +72,13 @@ const (
 
 // Headscale represents the base app of the service.
 type Headscale struct {
-	cfg        *Config
-	db         *gorm.DB
-	dbString   string
-	dbType     string
-	dbDebug    bool
-	privateKey *key.MachinePrivate
+	cfg             *Config
+	db              *gorm.DB
+	dbString        string
+	dbType          string
+	dbDebug         bool
+	privateKey      *key.MachinePrivate
+	noisePrivateKey *key.MachinePrivate
 
 	DERPMap    *tailcfg.DERPMap
 	DERPServer *DERPServer
@@ -120,11 +121,20 @@ func LookupTLSClientAuthMode(mode string) (tls.ClientAuthType, bool) {
 }
 
 func NewHeadscale(cfg *Config) (*Headscale, error) {
-	privKey, err := readOrCreatePrivateKey(cfg.PrivateKeyPath)
+	privateKey, err := readOrCreatePrivateKey(cfg.PrivateKeyPath)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read or create private key: %w", err)
 	}
 
+	noisePrivateKey, err := readOrCreatePrivateKey(cfg.NoisePrivateKeyPath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read or create noise private key: %w", err)
+	}
+
+	if privateKey.Equal(*noisePrivateKey) {
+		return nil, fmt.Errorf("private key and noise private key are the same")
+	}
+
 	var dbString string
 	switch cfg.DBtype {
 	case Postgres:
@@ -151,7 +161,8 @@ func NewHeadscale(cfg *Config) (*Headscale, error) {
 		cfg:                cfg,
 		dbType:             cfg.DBtype,
 		dbString:           dbString,
-		privateKey:         privKey,
+		privateKey:         privateKey,
+		noisePrivateKey:    noisePrivateKey,
 		aclRules:           tailcfg.FilterAllowAll, // default allowall
 		registrationCache:  registrationCache,
 		pollNetMapStreamWG: sync.WaitGroup{},
diff --git a/config-example.yaml b/config-example.yaml
index d3d155e..e090d91 100644
--- a/config-example.yaml
+++ b/config-example.yaml
@@ -41,6 +41,13 @@ grpc_allow_insecure: false
 # autogenerated if it's missing
 private_key_path: /var/lib/headscale/private.key
 
+# The Noise private key is used to encrypt the
+# traffic between headscale and Tailscale clients when
+# using the new Noise-based TS2021 protocol.
+# The noise private key file which will be
+# autogenerated if it's missing
+noise_private_key_path: /var/lib/headscale/noise_private.key
+
 # List of IP prefixes to allocate tailaddresses from.
 # Each prefix consists of either an IPv4 or IPv6 address,
 # and the associated prefix length, delimited by a slash.
diff --git a/config.go b/config.go
index 6935840..a792bab 100644
--- a/config.go
+++ b/config.go
@@ -34,6 +34,7 @@ type Config struct {
 	NodeUpdateCheckInterval        time.Duration
 	IPPrefixes                     []netaddr.IPPrefix
 	PrivateKeyPath                 string
+	NoisePrivateKeyPath            string
 	BaseDomain                     string
 	LogLevel                       zerolog.Level
 	DisableUpdateCheck             bool
@@ -487,6 +488,9 @@ func GetHeadscaleConfig() (*Config, error) {
 		PrivateKeyPath: AbsolutePathFromConfigPath(
 			viper.GetString("private_key_path"),
 		),
+		NoisePrivateKeyPath: AbsolutePathFromConfigPath(
+			viper.GetString("noise_private_key_path"),
+		),
 		BaseDomain: baseDomain,
 
 		DERP: derpConfig,