Add full IP pinning enforcement

api/client/alpn.go

@@ -55,6 +55,9 @@ type ALPNDialerConfig struct {
 	// CAs when connection upgrade is required. If not provided, it's assumed
 	// the proper CAs are already present in TLSConfig.
 	GetClusterCAs GetClusterCAsFunc
+	// PROXYHeaderGetter is used if present to get signed PROXY headers to propagate client's IP.
+	// Used by proxy's web server to make calls on behalf of connected clients.
+	PROXYHeaderGetter PROXYHeaderGetter
 }
 
 // ALPNDialer is a ContextDialer that dials a connection to the Proxy Service
@@ -132,6 +135,7 @@ func (d *ALPNDialer) DialContext(ctx context.Context, network, addr string) (net
 		WithInsecureSkipVerify(d.cfg.TLSConfig.InsecureSkipVerify),
 		WithALPNConnUpgrade(d.cfg.ALPNConnUpgradeRequired),
 		WithALPNConnUpgradePing(shouldALPNConnUpgradeWithPing(tlsConfig)),
+		WithPROXYHeaderGetter(d.cfg.PROXYHeaderGetter),
 	)
 
 	conn, err := dialer.DialContext(ctx, network, addr)

api/client/alpn_conn_upgrade.go

@@ -34,6 +34,7 @@ import (
 	"github.com/gravitational/teleport/api/defaults"
 	"github.com/gravitational/teleport/api/utils"
 	"github.com/gravitational/teleport/api/utils/pingconn"
+	"github.com/gravitational/teleport/api/utils/tlsutils"
 )
 
 // IsALPNConnUpgradeRequired returns true if a tunnel is required through a HTTP
@@ -162,35 +163,17 @@ func newALPNConnUpgradeDialer(dialer ContextDialer, tlsConfig *tls.Config, withP
 func (d *alpnConnUpgradeDialer) DialContext(ctx context.Context, network, addr string) (net.Conn, error) {
 	logrus.Debugf("ALPN connection upgrade for %v.", addr)
 
-	conn, err := d.dialer.DialContext(ctx, network, addr)
+	tlsConn, err := tlsutils.TLSDial(ctx, d.dialer, network, addr, d.tlsConfig.Clone())
 	if err != nil {
 		return nil, trace.Wrap(err)
 	}
-
-	// matching the behavior of tls.Dial
-	cfg := d.tlsConfig
-	if cfg == nil {
-		cfg = &tls.Config{}
-	}
-	if cfg.ServerName == "" {
-		colonPos := strings.LastIndex(addr, ":")
-		if colonPos == -1 {
-			colonPos = len(addr)
-		}
-		hostname := addr[:colonPos]
-
-		cfg = cfg.Clone()
-		cfg.ServerName = hostname
-	}
-
-	tlsConn := tls.Client(conn, cfg)
 	upgradeURL := url.URL{
 		Host:   addr,
 		Scheme: "https",
 		Path:   constants.WebAPIConnUpgrade,
 	}
 
-	conn, err = upgradeConnThroughWebAPI(tlsConn, upgradeURL, d.upgradeType())
+	conn, err := upgradeConnThroughWebAPI(tlsConn, upgradeURL, d.upgradeType())
 	if err != nil {
 		return nil, trace.NewAggregate(tlsConn.Close(), err)
 	}

api/client/client.go

@@ -338,6 +338,7 @@ func authConnect(ctx context.Context, params connectParams) (*Client, error) {
 		WithInsecureSkipVerify(params.cfg.InsecureAddressDiscovery),
 		WithALPNConnUpgrade(params.cfg.ALPNConnUpgradeRequired),
 		WithALPNConnUpgradePing(true), // Use Ping protocol for long-lived connections.
+		WithPROXYHeaderGetter(params.cfg.PROXYHeaderGetter),
 	)
 
 	clt := newClient(params.cfg, dialer, params.tlsConfig)
@@ -562,6 +563,9 @@ type Config struct {
 	// will perform necessary tests to decide if connection upgrade is
 	// required.
 	ALPNConnUpgradeRequired bool
+	// PROXYHeaderGetter returns signed PROXY header that is sent to allow Proxy to propagate client's real IP to the
+	// auth server from the Proxy's web server, when we create user's client for the web session.
+	PROXYHeaderGetter PROXYHeaderGetter
 }
 
 // CheckAndSetDefaults checks and sets default config values.

api/client/contextdialer.go

@@ -45,6 +45,9 @@ type dialConfig struct {
 	// connection upgrade. This is only effective when alpnConnUpgradeRequired
 	// is true.
 	alpnConnUpgradeWithPing bool
+	// proxyHeaderGetter is used if present to get signed PROXY headers to propagate client's IP.
+	// Used by proxy's web server to make calls on behalf of connected clients.
+	proxyHeaderGetter PROXYHeaderGetter
 }
 
 // WithInsecureSkipVerify specifies if dialing insecure when using an HTTPS proxy.
@@ -71,6 +74,14 @@ func WithALPNConnUpgradePing(alpnConnUpgradeWithPing bool) DialOption {
 	}
 }
 
+// WithPROXYHeaderGetter provides PROXY headers signer so client's real IP could be propagated.
+// Used by proxy's web server to make calls on behalf of connected clients.
+func WithPROXYHeaderGetter(proxyHeaderGetter PROXYHeaderGetter) DialProxyOption {
+	return func(cfg *dialProxyConfig) {
+		cfg.proxyHeaderGetter = proxyHeaderGetter
+	}
+}
+
 // DialOption allows setting options as functional arguments to api.NewDialer.
 type DialOption func(cfg *dialConfig)
 
@@ -96,12 +107,37 @@ func newDirectDialer(keepAlivePeriod, dialTimeout time.Duration) *net.Dialer {
 	}
 }
 
-func newProxyURLDialer(proxyURL *url.URL, dialer *net.Dialer, opts ...DialProxyOption) ContextDialer {
+func newProxyURLDialer(proxyURL *url.URL, dialer ContextDialer, opts ...DialProxyOption) ContextDialer {
 	return ContextDialerFunc(func(ctx context.Context, network, addr string) (net.Conn, error) {
 		return DialProxyWithDialer(ctx, proxyURL, addr, dialer, opts...)
 	})
 }
 
+// NewPROXYHeaderDialer makes a new dialer that can propagate client IP if signed PROXY header getter is present
+func NewPROXYHeaderDialer(dialer ContextDialer, headerGetter PROXYHeaderGetter) ContextDialer {
+	return ContextDialerFunc(func(ctx context.Context, network, addr string) (net.Conn, error) {
+		conn, err := dialer.DialContext(ctx, network, addr)
+		if err != nil {
+			return nil, trace.Wrap(err)
+		}
+
+		if headerGetter != nil {
+			signedHeader, err := headerGetter()
+			if err != nil {
+				conn.Close()
+				return nil, trace.Wrap(err)
+			}
+			_, err = conn.Write(signedHeader)
+			if err != nil {
+				conn.Close()
+				return nil, trace.Wrap(err)
+			}
+		}
+
+		return conn, nil
+	})
+}
+
 // tracedDialer ensures that the provided ContextDialerFunc is given a context
 // which contains tracing information. In the event that a grpc dial occurs without
 // a grpc.WithBlock dialing option, the context provided to the dial function will
@@ -136,9 +172,15 @@ func NewDialer(ctx context.Context, keepAlivePeriod, dialTimeout time.Duration,
 		// Base direct dialer.
 		var dialer ContextDialer = netDialer
 
+		// Wrap with PROXY header dialer if getter is present.
+		// Used by Proxy's web server to propagate real client IP when making calls on behalf of connected clients
+		if cfg.proxyHeaderGetter != nil {
+			dialer = NewPROXYHeaderDialer(dialer, cfg.proxyHeaderGetter)
+		}
+
 		// Wrap with proxy URL dialer if proxy URL is detected.
 		if proxyURL := utils.GetProxyURL(addr); proxyURL != nil {
-			dialer = newProxyURLDialer(proxyURL, netDialer, opts...)
+			dialer = newProxyURLDialer(proxyURL, dialer, opts...)
 		}
 
 		// Wrap with alpnConnUpgradeDialer if upgrade is required for TLS Routing.