Merge pull request #26 from progressive-kiwi/feat-mtls-support

Feat: mTLS support
2025-05-12 21:20:39 +01:00 · 2025-04-02 21:23:17 -04:00 · 2025-04-02 21:23:17 -04:00 · e7c8dbc1c8
commit e7c8dbc1c8
parent 72e0adc1bf d28e3ca5e8
9 changed files with 290 additions and 31 deletions
--- a/.gitignore
+++ b/.gitignore
@ -1,3 +1,6 @@
 newt
 .DS_Store
-bin/
+bin/
+.idea
+*.iml
+certs/
--- a/README.md
+++ b/README.md
@ -37,8 +37,9 @@ When Newt receives WireGuard control messages, it will use the information encod
 - `dns`: DNS server to use to resolve the endpoint
 - `log-level` (optional): The log level to use. Default: INFO
 - `updown` (optional): A script to be called when targets are added or removed.
- 
-Example:
+- `tls-client-cert` (optional): Client certificate (p12 or pfx) for mTLS. See [mTLS](#mtls)
+
+- Example:

 ```bash
 ./newt \
@ -107,6 +108,38 @@ Returning a string from the script in the format of a target (`ip:dst` so `10.0.

 You can look at updown.py as a reference script to get started!

+### mTLS
+Newt supports mutual TLS (mTLS) authentication, if the server has been configured to request a client certificate.
+* Only PKCS12 (.p12 or .pfx) file format is accepted
+* The PKCS12 file must contain: 
+  * Private key
+  * Public certificate
+  * CA certificate
+* Encrypted PKCS12 files are currently not supported
+
+Examples:
+
+```bash
+./newt \
+--id 31frd0uzbjvp721 \
+--secret h51mmlknrvrwv8s4r1i210azhumt6isgbpyavxodibx1k2d6 \
+--endpoint https://example.com \
+--tls-client-cert ./client.p12
+```
+
+```yaml
+services:
+  newt:
+    image: fosrl/newt
+    container_name: newt
+    restart: unless-stopped
+    environment:
+      - PANGOLIN_ENDPOINT=https://example.com
+      - NEWT_ID=2ix2t8xk22ubpfy 
+      - NEWT_SECRET=nnisrfsdfc7prqsp9ewo1dvtvci50j5uiqotez00dgap0ii2 
+      - TLS_CLIENT_CERT=./client.p12 
+```
+
 ## Build

 ### Container 
--- a/go.mod
+++ b/go.mod
@ -10,6 +10,7 @@ require (
 	golang.zx2c4.com/wireguard v0.0.0-20231211153847-12269c276173
 	golang.zx2c4.com/wireguard/wgctrl v0.0.0-20230429144221-925a1e7659e6
 	gvisor.dev/gvisor v0.0.0-20230927004350-cbd86285d259
+	software.sslmate.com/src/go-pkcs12 v0.5.0
 )

 require (
--- a/go.sum
+++ b/go.sum
@ -20,3 +20,5 @@ golang.zx2c4.com/wireguard/wgctrl v0.0.0-20230429144221-925a1e7659e6 h1:CawjfCvY
 golang.zx2c4.com/wireguard/wgctrl v0.0.0-20230429144221-925a1e7659e6/go.mod h1:3rxYc4HtVcSG9gVaTs2GEBdehh+sYPOwKtyUWEOTb80=
 gvisor.dev/gvisor v0.0.0-20230927004350-cbd86285d259 h1:TbRPT0HtzFP3Cno1zZo7yPzEEnfu8EjLfl6IU9VfqkQ=
 gvisor.dev/gvisor v0.0.0-20230927004350-cbd86285d259/go.mod h1:AVgIgHMwK63XvmAzWG9vLQ41YnVHN0du0tEC46fI7yY=
+software.sslmate.com/src/go-pkcs12 v0.5.0 h1:EC6R394xgENTpZ4RltKydeDUjtlM5drOYIG9c6TVj2M=
+software.sslmate.com/src/go-pkcs12 v0.5.0/go.mod h1:Qiz0EyvDRJjjxGyUQa2cCNZn/wMyzrRJ/qcDXOQazLI=
--- a/main.go
+++ b/main.go
@ -340,16 +340,17 @@ func resolveDomain(domain string) (string, error) {
 }

 var (
-	endpoint     string
-	id           string
-	secret       string
-	mtu          string
-	mtuInt       int
-	dns          string
-	privateKey   wgtypes.Key
-	err          error
-	logLevel     string
-	updownScript string
+	endpoint      string
+	id            string
+	secret        string
+	mtu           string
+	mtuInt        int
+	dns           string
+	privateKey    wgtypes.Key
+	err           error
+	logLevel      string
+	updownScript  string
+	tlsPrivateKey string
 )

 func main() {
@ -361,6 +362,7 @@ func main() {
 	dns = os.Getenv("DNS")
 	logLevel = os.Getenv("LOG_LEVEL")
 	updownScript = os.Getenv("UPDOWN_SCRIPT")
+	tlsPrivateKey = os.Getenv("TLS_CLIENT_CERT")

 	if endpoint == "" {
 		flag.StringVar(&endpoint, "endpoint", "", "Endpoint of your pangolin server")
@ -383,6 +385,9 @@ func main() {
 	if updownScript == "" {
 		flag.StringVar(&updownScript, "updown", "", "Path to updown script to be called when targets are added or removed")
 	}
+	if tlsPrivateKey == "" {
+		flag.StringVar(&tlsPrivateKey, "tls-client-cert", "", "Path to client certificate used for mTLS")
+	}

 	// do a --version check
 	version := flag.Bool("version", false, "Print the version")
@ -408,12 +413,16 @@ func main() {
 	if err != nil {
 		logger.Fatal("Failed to generate private key: %v", err)
 	}
-
+	var opt websocket.ClientOption
+	if tlsPrivateKey != "" {
+		opt = websocket.WithTLSConfig(tlsPrivateKey)
+	}
 	// Create a new client
 	client, err := websocket.NewClient(
 		id,     // CLI arg takes precedence
 		secret, // CLI arg takes precedence
 		endpoint,
+		opt,
 	)
 	if err != nil {
 		logger.Fatal("Failed to create client: %v", err)
@ -642,10 +651,13 @@ persistent_keepalive_interval=5`, fixKey(fmt.Sprintf("%s", privateKey)), fixKey(
 	// Wait for interrupt signal
 	sigCh := make(chan os.Signal, 1)
 	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
-	<-sigCh
+	sigReceived := <-sigCh

 	// Cleanup
-	dev.Close()
+	logger.Info("Received %s signal, stopping", sigReceived.String())
+	if dev != nil {
+		dev.Close()
+	}
 }

 func parseTargetData(data interface{}) (TargetData, error) {
--- a/self-signed-certs-for-mtls.sh
+++ b/self-signed-certs-for-mtls.sh
@ -0,0 +1,125 @@
+#!/usr/bin/env bash
+set -eu
+
+echo -n "Enter username for certs (eg alice): "
+read CERT_USERNAME
+echo
+
+echo -n "Enter domain of user (eg example.com): "
+read DOMAIN
+echo
+
+# Prompt for password at the start
+echo -n "Enter password for certificate: "
+read -s PASSWORD
+echo
+echo -n "Confirm password: "
+read -s PASSWORD2
+echo
+
+if [ "$PASSWORD" != "$PASSWORD2" ]; then
+    echo "Passwords don't match!"
+    exit 1
+fi
+CA_DIR="./certs/ca"
+CLIENT_DIR="./certs/clients"
+FILE_PREFIX=$(echo "$CERT_USERNAME-at-$DOMAIN" | sed 's/\./-/')
+
+mkdir -p "$CA_DIR"
+mkdir -p "$CLIENT_DIR"
+
+if [ ! -f "$CA_DIR/ca.crt" ]; then
+# Generate CA private key
+  openssl genrsa -out "$CA_DIR/ca.key" 4096
+  echo "CA key ✅"
+
+  # Generate CA root certificate
+  openssl req -x509 -new -nodes \
+    -key "$CA_DIR/ca.key" \
+    -sha256 \
+    -days 3650 \
+    -out "$CA_DIR/ca.crt" \
+    -subj "/C=US/ST=State/L=City/O=Organization/OU=Unit/CN=ca.$DOMAIN"
+
+  echo "CA cert ✅"
+fi
+
+# Generate client private key
+openssl genrsa -aes256 -passout pass:"$PASSWORD" -out "$CLIENT_DIR/$FILE_PREFIX.key" 2048
+echo "Client key ✅"
+
+# Generate client Certificate Signing Request (CSR)
+openssl req -new \
+  -key "$CLIENT_DIR/$FILE_PREFIX.key" \
+  -out "$CLIENT_DIR/$FILE_PREFIX.csr" \
+  -passin pass:"$PASSWORD" \
+  -subj "/C=US/ST=State/L=City/O=Organization/OU=Unit/CN=$CERT_USERNAME@$DOMAIN"
+echo "Client cert ✅"
+
+echo -n "Signing client cert..."
+# Create client certificate configuration file
+cat > "$CLIENT_DIR/$FILE_PREFIX.ext" << EOF
+authorityKeyIdentifier=keyid,issuer
+basicConstraints=CA:FALSE
+keyUsage = digitalSignature, nonRepudiation, keyEncipherment, dataEncipherment
+subjectAltName = @alt_names
+
+[alt_names]
+DNS.1 = $DOMAIN
+EOF
+
+# Generate client certificate signed by CA
+openssl x509 -req \
+  -in "$CLIENT_DIR/$FILE_PREFIX.csr" \
+  -CA "$CA_DIR/ca.crt" \
+  -CAkey "$CA_DIR/ca.key" \
+  -CAcreateserial \
+  -out "$CLIENT_DIR/$FILE_PREFIX.crt" \
+  -days 365 \
+  -sha256 \
+  -extfile "$CLIENT_DIR/$FILE_PREFIX.ext"
+
+# Verify the client certificate
+openssl verify -CAfile "$CA_DIR/ca.crt" "$CLIENT_DIR/$FILE_PREFIX.crt"
+echo "Signed ✅"
+
+# Create encrypted PEM bundle
+openssl rsa -in "$CLIENT_DIR/$FILE_PREFIX.key" -passin pass:"$PASSWORD" \
+    | cat "$CLIENT_DIR/$FILE_PREFIX.crt" - > "$CLIENT_DIR/$FILE_PREFIX-bundle.enc.pem"
+
+
+# Convert to PKCS12
+echo "Converting to PKCS12 format..."
+openssl pkcs12 -export \
+  -out "$CLIENT_DIR/$FILE_PREFIX.enc.p12" \
+  -inkey "$CLIENT_DIR/$FILE_PREFIX.key" \
+  -in "$CLIENT_DIR/$FILE_PREFIX.crt" \
+  -certfile "$CA_DIR/ca.crt" \
+  -name "$CERT_USERNAME@$DOMAIN" \
+  -passin pass:"$PASSWORD" \
+  -passout pass:"$PASSWORD"
+echo "Converted to encrypted p12 for macOS ✅"
+
+# Convert to PKCS12 format without encryption
+echo "Converting to non-encrypted PKCS12 format..."
+openssl pkcs12 -export \
+  -out "$CLIENT_DIR/$FILE_PREFIX.p12" \
+  -inkey "$CLIENT_DIR/$FILE_PREFIX.key" \
+  -in "$CLIENT_DIR/$FILE_PREFIX.crt" \
+  -certfile "$CA_DIR/ca.crt" \
+  -name "$CERT_USERNAME@$DOMAIN" \
+  -passin pass:"$PASSWORD" \
+  -passout pass:""
+echo "Converted to non-encrypted p12  ✅"
+
+# Clean up intermediate files
+rm "$CLIENT_DIR/$FILE_PREFIX.csr" "$CLIENT_DIR/$FILE_PREFIX.ext" "$CA_DIR/ca.srl"
+echo
+echo
+
+echo "CA certificate:     $CA_DIR/ca.crt"
+echo "CA private key:     $CA_DIR/ca.key"
+echo "Client certificate: $CLIENT_DIR/$FILE_PREFIX.crt"
+echo "Client private key: $CLIENT_DIR/$FILE_PREFIX.key"
+echo "Client cert bundle: $CLIENT_DIR/$FILE_PREFIX.p12"
+echo "Client cert bundle (encrypted): $CLIENT_DIR/$FILE_PREFIX.enc.p12"
--- a/websocket/client.go
+++ b/websocket/client.go
@ -2,27 +2,29 @@ package websocket

 import (
 	"bytes"
+	"crypto/tls"
+	"crypto/x509"
 	"encoding/json"
 	"fmt"
 	"net/http"
 	"net/url"
+	"os"
+	"software.sslmate.com/src/go-pkcs12"
 	"strings"
 	"sync"
 	"time"

 	"github.com/fosrl/newt/logger"
-
 	"github.com/gorilla/websocket"
 )

 type Client struct {
-	conn        *websocket.Conn
-	config      *Config
-	baseURL     string
-	handlers    map[string]MessageHandler
-	done        chan struct{}
-	handlersMux sync.RWMutex
-
+	conn              *websocket.Conn
+	config            *Config
+	baseURL           string
+	handlers          map[string]MessageHandler
+	done              chan struct{}
+	handlersMux       sync.RWMutex
 	reconnectInterval time.Duration
 	isConnected       bool
 	reconnectMux      sync.RWMutex
@ -41,6 +43,12 @@ func WithBaseURL(url string) ClientOption {
 	}
 }

+func WithTLSConfig(tlsClientCertPath string) ClientOption {
+	return func(c *Client) {
+		c.config.TlsClientCert = tlsClientCertPath
+	}
+}
+
 func (c *Client) OnConnect(callback func() error) {
 	c.onConnect = callback
 }
@ -63,8 +71,13 @@ func NewClient(newtID, secret string, endpoint string, opts ...ClientOption) (*C
 	}

 	// Apply options before loading config
-	for _, opt := range opts {
-		opt(client)
+	if opts != nil {
+		for _, opt := range opts {
+			if opt == nil {
+				continue
+			}
+			opt(client)
+		}
 	}

 	// Load existing config if available
@ -149,6 +162,14 @@ func (c *Client) getToken() (string, error) {
 	// Ensure we have the base URL without trailing slashes
 	baseEndpoint := strings.TrimRight(baseURL.String(), "/")

+	var tlsConfig *tls.Config = nil
+	if c.config.TlsClientCert != "" {
+		tlsConfig, err = loadClientCertificate(c.config.TlsClientCert)
+		if err != nil {
+			return "", fmt.Errorf("failed to load certificate %s: %w", c.config.TlsClientCert, err)
+		}
+	}
+
 	// If we already have a token, try to use it
 	if c.config.Token != "" {
 		tokenCheckData := map[string]interface{}{
@ -177,6 +198,11 @@ func (c *Client) getToken() (string, error) {

 		// Make the request
 		client := &http.Client{}
+		if tlsConfig != nil {
+			client.Transport = &http.Transport{
+				TLSClientConfig: tlsConfig,
+			}
+		}
 		resp, err := client.Do(req)
 		if err != nil {
 			return "", fmt.Errorf("failed to check token validity: %w", err)
@ -220,6 +246,11 @@ func (c *Client) getToken() (string, error) {

 	// Make the request
 	client := &http.Client{}
+	if tlsConfig != nil {
+		client.Transport = &http.Transport{
+			TLSClientConfig: tlsConfig,
+		}
+	}
 	resp, err := client.Do(req)
 	if err != nil {
 		return "", fmt.Errorf("failed to request new token: %w", err)
@ -295,7 +326,16 @@ func (c *Client) establishConnection() error {
 	u.RawQuery = q.Encode()

 	// Connect to WebSocket
-	conn, _, err := websocket.DefaultDialer.Dial(u.String(), nil)
+	dialer := websocket.DefaultDialer
+	if c.config.TlsClientCert != "" {
+		logger.Info("Adding tls to req")
+		tlsConfig, err := loadClientCertificate(c.config.TlsClientCert)
+		if err != nil {
+			return fmt.Errorf("failed to load certificate %s: %w", c.config.TlsClientCert, err)
+		}
+		dialer.TLSClientConfig = tlsConfig
+	}
+	conn, _, err := dialer.Dial(u.String(), nil)
 	if err != nil {
 		return fmt.Errorf("failed to connect to WebSocket: %w", err)
 	}
@ -353,3 +393,42 @@ func (c *Client) setConnected(status bool) {
 	defer c.reconnectMux.Unlock()
 	c.isConnected = status
 }
+
+// LoadClientCertificate Helper method to load client certificates
+func loadClientCertificate(p12Path string) (*tls.Config, error) {
+	logger.Info("Loading tls-client-cert %s", p12Path)
+	// Read the PKCS12 file
+	p12Data, err := os.ReadFile(p12Path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read PKCS12 file: %w", err)
+	}
+
+	// Parse PKCS12 with empty password for non-encrypted files
+	privateKey, certificate, caCerts, err := pkcs12.DecodeChain(p12Data, "")
+	if err != nil {
+		return nil, fmt.Errorf("failed to decode PKCS12: %w", err)
+	}
+
+	// Create certificate
+	cert := tls.Certificate{
+		Certificate: [][]byte{certificate.Raw},
+		PrivateKey:  privateKey,
+	}
+
+	// Optional: Add CA certificates if present
+	rootCAs, err := x509.SystemCertPool()
+	if err != nil {
+		return nil, fmt.Errorf("failed to load system cert pool: %w", err)
+	}
+	if len(caCerts) > 0 {
+		for _, caCert := range caCerts {
+			rootCAs.AddCert(caCert)
+		}
+	}
+
+	// Create TLS configuration
+	return &tls.Config{
+		Certificates: []tls.Certificate{cert},
+		RootCAs:      rootCAs,
+	}, nil
+}
--- a/websocket/config.go
+++ b/websocket/config.go
@ -54,6 +54,9 @@ func (c *Client) loadConfig() error {
 	if c.config.Secret == "" {
 		c.config.Secret = config.Secret
 	}
+	if c.config.TlsClientCert == "" {
+		c.config.TlsClientCert = config.TlsClientCert
+	}
 	if c.config.Endpoint == "" {
 		c.config.Endpoint = config.Endpoint
 		c.baseURL = config.Endpoint
--- a/websocket/types.go
+++ b/websocket/types.go
@ -1,10 +1,11 @@
 package websocket

 type Config struct {
-	NewtID   string `json:"newtId"`
-	Secret   string `json:"secret"`
-	Token    string `json:"token"`
-	Endpoint string `json:"endpoint"`
+	NewtID        string `json:"newtId"`
+	Secret        string `json:"secret"`
+	Token         string `json:"token"`
+	Endpoint      string `json:"endpoint"`
+	TlsClientCert string `json:"tlsClientCert"`
 }

 type TokenResponse struct {