PSK support for v2

nbrownus · nbrownus · commit 2c78b0dfde14 · 2024-11-13T17:03:35.000-06:00
diff --git a/connection_state.go b/connection_state.go
@@ -27,7 +27,7 @@ type ConnectionState struct {
 	writeLock      sync.Mutex
 }
 
-func NewConnectionState(l *logrus.Logger, cs *CertState, crt cert.Certificate, initiator bool, pattern noise.HandshakePattern) (*ConnectionState, error) {
+func NewConnectionState(l *logrus.Logger, cs *CertState, crt cert.Certificate, initiator bool, pattern noise.HandshakePattern, psk []byte) (*ConnectionState, error) {
 	var dhFunc noise.DHFunc
 	switch crt.Curve() {
 	case cert.Curve_CURVE25519:
@@ -56,13 +56,12 @@ func NewConnectionState(l *logrus.Logger, cs *CertState, crt cert.Certificate, i
 	b.Update(l, 0)
 
 	hs, err := noise.NewHandshakeState(noise.Config{
-		CipherSuite:   ncs,
-		Random:        rand.Reader,
-		Pattern:       pattern,
-		Initiator:     initiator,
-		StaticKeypair: static,
-		//NOTE: These should come from CertState (pki.go) when we finally implement it
-		PresharedKey:          []byte{},
+		CipherSuite:           ncs,
+		Random:                rand.Reader,
+		Pattern:               pattern,
+		Initiator:             initiator,
+		StaticKeypair:         static,
+		PresharedKey:          psk,
 		PresharedKeyPlacement: 0,
 	})
 	if err != nil {
diff --git a/e2e/handshakes_test.go b/e2e/handshakes_test.go
@@ -1105,6 +1105,138 @@ func TestV2NonPrimaryWithLighthouse(t *testing.T) {
 	theirControl.Stop()
 }
 
+func TestPSK(t *testing.T) {
+	tests := []struct {
+		name         string
+		myPskMode    nebula.PskMode
+		theirPskMode nebula.PskMode
+	}{
+		// All accepting
+		{
+			name:         "both accepting",
+			myPskMode:    nebula.PskAccepting,
+			theirPskMode: nebula.PskAccepting,
+		},
+
+		// accepting and sending both ways
+		{
+			name:         "accepting to sending",
+			myPskMode:    nebula.PskAccepting,
+			theirPskMode: nebula.PskSending,
+		},
+		{
+			name:         "sending to accepting",
+			myPskMode:    nebula.PskSending,
+			theirPskMode: nebula.PskAccepting,
+		},
+
+		// All sending
+		{
+			name:         "sending to sending",
+			myPskMode:    nebula.PskSending,
+			theirPskMode: nebula.PskSending,
+		},
+
+		// enforced and sending both ways
+		{
+			name:         "enforced to sending",
+			myPskMode:    nebula.PskEnforced,
+			theirPskMode: nebula.PskSending,
+		},
+		{
+			name:         "sending to enforced",
+			myPskMode:    nebula.PskSending,
+			theirPskMode: nebula.PskEnforced,
+		},
+
+		// All enforced
+		{
+			name:         "both enforced",
+			myPskMode:    nebula.PskEnforced,
+			theirPskMode: nebula.PskEnforced,
+		},
+
+		// Enforced can technically handshake with an accepting node, but it is bad to be in this state
+		{
+			name:         "enforced to accepting",
+			myPskMode:    nebula.PskEnforced,
+			theirPskMode: nebula.PskAccepting,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			var myPskSettings, theirPskSettings m
+
+			switch test.myPskMode {
+			case nebula.PskAccepting:
+				myPskSettings = m{"psk": &m{"mode": "accepting", "keys": []string{"garbage0", "this is a key"}}}
+			case nebula.PskSending:
+				myPskSettings = m{"psk": &m{"mode": "sending", "keys": []string{"this is a key", "garbage1"}}}
+			case nebula.PskEnforced:
+				myPskSettings = m{"psk": &m{"mode": "enforced", "keys": []string{"this is a key", "garbage2"}}}
+			}
+
+			switch test.theirPskMode {
+			case nebula.PskAccepting:
+				theirPskSettings = m{"psk": &m{"mode": "accepting", "keys": []string{"garbage3", "this is a key"}}}
+			case nebula.PskSending:
+				theirPskSettings = m{"psk": &m{"mode": "sending", "keys": []string{"this is a key", "garbage4"}}}
+			case nebula.PskEnforced:
+				theirPskSettings = m{"psk": &m{"mode": "enforced", "keys": []string{"this is a key", "garbage5"}}}
+			}
+
+			ca, _, caKey, _ := cert_test.NewTestCaCert(cert.Version2, cert.Curve_CURVE25519, time.Now(), time.Now().Add(10*time.Minute), nil, nil, nil)
+			myControl, myVpnIp, myUdpAddr, _ := newSimpleServer(cert.Version2, ca, caKey, "me", "10.0.0.1/24", myPskSettings)
+			theirControl, theirVpnIp, theirUdpAddr, _ := newSimpleServer(cert.Version2, ca, caKey, "them", "10.0.0.2/24", theirPskSettings)
+
+			myControl.InjectLightHouseAddr(theirVpnIp[0].Addr(), theirUdpAddr)
+			r := router.NewR(t, myControl, theirControl)
+
+			// Start the servers
+			myControl.Start()
+			theirControl.Start()
+
+			t.Log("Route until we see our cached packet flow")
+			myControl.InjectTunUDPPacket(theirVpnIp[0].Addr(), 80, myVpnIp[0].Addr(), 80, []byte("Hi from me"))
+			r.RouteForAllExitFunc(func(p *udp.Packet, c *nebula.Control) router.ExitType {
+				h := &header.H{}
+				err := h.Parse(p.Data)
+				if err != nil {
+					panic(err)
+				}
+
+				// If this is the stage 1 handshake packet and I am configured to send with a psk, my cert name should
+				// not appear. It would likely be more obvious to unmarshal the payload and check but this works fine for now
+				if test.myPskMode == nebula.PskEnforced || test.myPskMode == nebula.PskSending {
+					if h.Type == 0 && h.MessageCounter == 1 {
+						assert.NotContains(t, string(p.Data), "test me")
+					}
+				}
+
+				if p.To == theirUdpAddr && h.Type == 1 {
+					return router.RouteAndExit
+				}
+
+				return router.KeepRouting
+			})
+
+			t.Log("My cached packet should be received by them")
+			myCachedPacket := theirControl.GetFromTun(true)
+			assertUdpPacket(t, []byte("Hi from me"), myCachedPacket, myVpnIp[0].Addr(), theirVpnIp[0].Addr(), 80, 80)
+
+			t.Log("Test the tunnel with them")
+			assertHostInfoPair(t, myUdpAddr, theirUdpAddr, myVpnIp, theirVpnIp, myControl, theirControl)
+			assertTunnel(t, myVpnIp[0].Addr(), theirVpnIp[0].Addr(), myControl, theirControl, r)
+
+			myControl.Stop()
+			theirControl.Stop()
+			//TODO: assert hostmaps
+		})
+	}
+
+}
+
 //TODO: test
 // Race winner renews and handshakes
 // Race loser renews and handshakes
diff --git a/e2e/router/router.go b/e2e/router/router.go
@@ -111,10 +111,6 @@ type ExitFunc func(packet *udp.Packet, receiver *nebula.Control) ExitType
 func NewR(t testing.TB, controls ...*nebula.Control) *R {
 	ctx, cancel := context.WithCancel(context.Background())
 
-	if err := os.MkdirAll("mermaid", 0755); err != nil {
-		panic(err)
-	}
-
 	r := &R{
 		controls:     make(map[netip.AddrPort]*nebula.Control),
 		vpnControls:  make(map[netip.Addr]*nebula.Control),
@@ -194,6 +190,9 @@ func (r *R) renderFlow() {
 		return
 	}
 
+	if err := os.MkdirAll(filepath.Dir(r.fn), 0755); err != nil {
+		panic(err)
+	}
 	f, err := os.OpenFile(r.fn, os.O_CREATE|os.O_TRUNC|os.O_RDWR, 0644)
 	if err != nil {
 		panic(err)
diff --git a/examples/config.yml b/examples/config.yml
@@ -19,6 +19,38 @@ pki:
   # After all hosts in the mesh are using a v2 certificate then v1 certificates are no longer needed.
   # default_version: 1
 
+  # psk can be used to mask the contents of handshakes.
+  psk:
+    # `mode` defines how the pre shared keys can be used in a handshake.
+    # `accepting` (the default) will initiate handshakes using an empty key and will try to use any keys provided when
+    # receiving handshakes, including an empty key.
+    # `sending` will initiate handshakes with the first key provided and will try to use any keys provided when
+    # receiving handshakes, including an empty key.
+    # `enforced` will initiate handshakes with the first psk key provided and will try to use any keys provided when
+    # responding to handshakes. An empty key will not be allowed.
+    #
+    # To change a mesh from not using a psk to enforcing psk:
+    # 1. Leave `mode` as `accepting` and configure `psk.keys` to match on all nodes in the mesh and reload.
+    # 2. Change `mode` to `sending` on all nodes in the mesh and reload.
+    # 3. Change `mode` to `enforced` on all nodes in the mesh and reload.
+    #mode: accepting
+
+    # The keys provided are sent through hkdf to ensure the shared secret used in the noise protocol is the
+    # correct byte length.
+    #
+    # Only the first key is used for outbound handshakes but all keys provided will be tried in the order specified, on
+    # incoming handshakes. This is to allow for psk rotation.
+    #
+    # To rotate a primary key:
+    # 1. Put the new key in the 2nd slot on every node in the mesh and reload.
+    # 2. Move the key from the 2nd slot to the 1st slot, the old primary key is now in the 2nd slot, reload.
+    # 3. Remove the old primary key once it is no longer in use on every node in the mesh and reload.
+    #keys:
+    # - shared secret string, this one is used in all outbound handshakes # This is the primary key used when sending handshakes
+    # - this is a fallback key, received handshakes can use this
+    # - another fallback, received handshakes can use this one too
+    # - "\x68\x65\x6c\x6c\x6f\x20\x66\x72\x69\x65\x6e\x64\x73" # for raw bytes if you desire
+
 # The static host map defines a set of hosts with fixed IP addresses on the internet (or any network).
 # A host can have multiple fixed IP addresses defined here, and nebula will try each when establishing a tunnel.
 # The syntax is:
@@ -309,7 +341,6 @@ logging:
   # after receiving the response for lighthouse queries
   #trigger_buffer: 64
 
-
 # Nebula security group configuration
 firewall:
   # Action to take when a packet is not allowed by the firewall rules.
diff --git a/handshake_ix.go b/handshake_ix.go
@@ -50,7 +50,7 @@ func ixHandshakeStage0(f *Interface, hh *HandshakeHostInfo) bool {
 			Error("Unable to handshake with host because no certificate handshake bytes is available")
 	}
 
-	ci, err := NewConnectionState(f.l, cs, crt, true, noise.HandshakeIX)
+	ci, err := NewConnectionState(f.l, cs, crt, true, noise.HandshakeIX, cs.psk.primary)
 	if err != nil {
 		f.l.WithError(err).WithField("vpnAddrs", hh.hostinfo.vpnAddrs).
 			WithField("handshake", m{"stage": 0, "style": "ix_psk0"}).
@@ -104,34 +104,53 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 			Error("Unable to handshake with host because no certificate is available")
 	}
 
-	ci, err := NewConnectionState(f.l, cs, crt, false, noise.HandshakeIX)
-	if err != nil {
-		f.l.WithError(err).WithField("udpAddr", addr).
-			WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).
-			Error("Failed to create connection state")
-		return
-	}
+	var (
+		err error
+		ci  *ConnectionState
+		msg []byte
+	)
 
-	// Mark packet 1 as seen so it doesn't show up as missed
-	ci.window.Update(f.l, 1)
+	hs := &NebulaHandshake{}
 
-	msg, _, _, err := ci.H.ReadMessage(nil, packet[header.Len:])
-	if err != nil {
-		f.l.WithError(err).WithField("udpAddr", addr).
-			WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).
-			Error("Failed to call noise.ReadMessage")
-		return
+	for _, psk := range cs.psk.keys {
+		ci, err = NewConnectionState(f.l, cs, crt, false, noise.HandshakeIX, psk)
+		if err != nil {
+			//TODO: should be bother logging this, if we have multiple psks and the error is unrelated it will be verbose.
+			f.l.WithError(err).WithField("udpAddr", addr).
+				WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).
+				Error("Failed to create connection state")
+			continue
+		}
+
+		msg, _, _, err = ci.H.ReadMessage(nil, packet[header.Len:])
+		if err != nil {
+			// Calls to ReadMessage with an incorrect psk should fail, try the next one if we have one
+			continue
+		}
+
+		// Sometimes ReadMessage returns fine with a nil psk even if the handshake is using a psk, ensure our protobuf
+		// comes out clean as well
+		err = hs.Unmarshal(msg)
+		if err == nil {
+			// There was no error, we can continue with this handshake
+			break
+		}
+
+		// The unmarshal failed, try the next psk if we have one
 	}
 
-	hs := &NebulaHandshake{}
-	err = hs.Unmarshal(msg)
+	// We finished with an error, log it and get out
 	if err != nil || hs.Details == nil {
-		f.l.WithError(err).WithField("udpAddr", addr).
+		// We aren't logging the error here because we can't be sure of the failure when using psk
+		f.l.WithField("udpAddr", addr).
 			WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).
-			Error("Failed unmarshal handshake message")
+			Error("Was unable to decrypt the handshake")
 		return
 	}
 
+	// Mark packet 1 as seen so it doesn't show up as missed
+	ci.window.Update(f.l, 1)
+
 	remoteCert, err := cert.RecombineAndValidate(cert.Version(hs.Details.CertVersion), hs.Details.Cert, ci.H.PeerStatic(), ci.Curve(), f.pki.GetCAPool())
 	if err != nil {
 		e := f.l.WithError(err).WithField("udpAddr", addr).
diff --git a/pki.go b/pki.go
@@ -38,6 +38,8 @@ type CertState struct {
 	pkcs11Backed   bool
 	cipher         string
 
+	psk *Psk
+
 	myVpnNetworks            []netip.Prefix
 	myVpnNetworksTable       *bart.Table[struct{}]
 	myVpnAddrs               []netip.Addr
@@ -97,6 +99,14 @@ func (p *PKI) reload(c *config.C, initial bool) error {
 		err.Log(p.l)
 	}
 
+	err = p.reloadCAPool(c)
+	if err != nil {
+		if initial {
+			return err
+		}
+		err.Log(p.l)
+	}
+
 	return nil
 }
 
@@ -181,6 +191,16 @@ func (p *PKI) reloadCerts(c *config.C, initial bool) *util.ContextualError {
 		}
 	}
 
+	psk, err := NewPskFromConfig(c)
+	if err != nil {
+		return util.NewContextualError("Failed to load psk from config", nil, err)
+	}
+	if len(psk.keys) > 0 {
+		p.l.WithField("pskMode", psk.mode).WithField("keysLen", len(psk.keys)).
+			Info("pre shared keys are in use")
+	}
+	newState.psk = psk
+
 	p.cs.Store(newState)
 
 	//TODO: newState needs a stringer that does json
diff --git a/psk.go b/psk.go
diff --git a/psk_test.go b/psk_test.go
