Merge branch 'prevent-upgrade'

CHANGELOG.md

@@ -19,6 +19,10 @@ Line wrap the file at 100 chars.                                              Th
 * **Fixed**: for any bug fixes.
 * **Security**: in case of vulnerabilities.
 
+## [1.0.4] - 2024-10-01
+### Changed
+- Prevent upgrading an already upgraded tunnel.
+
 
 ## [1.0.3] - 2024-07-04
 ### Changed

cmd/mullvad-upgrade-tunnel/main.go

@@ -41,6 +41,8 @@ func main() {
 	if err := wgephemeralpeer.Connect(*iface, kems...); err != nil {
 		if err == context.DeadlineExceeded {
 			fmt.Fprintf(os.Stderr, "unable to connect to relay, ensure you are able to connect to 10.64.0.1 on TCP port 1337\n")
+		} else if err == wgephemeralpeer.ErrPeerAlreadyUpgraded {
+			fmt.Fprintf(os.Stderr, "unable to upgrade tunnel, %v\n", err)
 		} else {
 			fmt.Fprintf(os.Stderr, "unable to connect ephemeral peer, %v\n", err)
 		}

wg.go

@@ -11,6 +11,7 @@ import (
 var (
 	ErrDeviceDoesNotExist   = errors.New("device does not exist")
 	ErrInvalidNumberOfPeers = errors.New("invalid number of peers")
+	ErrPeerAlreadyUpgraded  = errors.New("peer has already been upgraded")
 )
 
 func (ep *ephemeralPeer) getPublicKey(iface string) (*wgtypes.Key, error) {
@@ -28,6 +29,13 @@ func (ep *ephemeralPeer) getPublicKey(iface string) (*wgtypes.Key, error) {
 		return nil, err
 	}
 
+	var zeroKey wgtypes.Key
+	for _, p := range device.Peers {
+		if p.PresharedKey != zeroKey {
+			return nil, ErrPeerAlreadyUpgraded
+		}
+	}
+
 	publicKey := device.PrivateKey.PublicKey()
 	return &publicKey, nil
 }