TUN-1196: Allow TLS config client CA and root CA to be constructed from multiple certificates

cmd/cloudflared/tunnel/cmd.go

@@ -438,7 +438,7 @@ func tunnelFlags(shouldHide bool) []cli.Flag {
 		}),
 		altsrc.NewStringFlag(&cli.StringFlag{
 			Name:    "cacert",
-			Usage:   "Certificate Authority authenticating the Cloudflare tunnel connection.",
+			Usage:   "Certificate Authority authenticating connections with Cloudflare's edge network.",
 			EnvVars: []string{"TUNNEL_CACERT"},
 			Hidden:  true,
 		}),

cmd/cloudflared/tunnel/configuration.go

@@ -198,12 +198,18 @@ func prepareTunnelConfig(c *cli.Context, buildInfo *origin.BuildInfo, version st
 		return nil, errors.Wrap(err, "unable to connect to the origin")
 	}
 
+	toEdgeTLSConfig, err := createTunnelConfig(c)
+	if err != nil {
+		logger.WithError(err).Error("unable to create TLS config to connect with edge")
+		return nil, errors.Wrap(err, "unable to create TLS config to connect with edge")
+	}
+
 	return &origin.TunnelConfig{
 		EdgeAddrs:          c.StringSlice("edge"),
 		OriginUrl:          originURL,
 		Hostname:           hostname,
 		OriginCert:         originCert,
-		TlsConfig:          tlsconfig.CreateTunnelConfig(c, c.StringSlice("edge")),
+		TlsConfig:          toEdgeTLSConfig,
 		ClientTlsConfig:    httpTransport.TLSClientConfig,
 		Retries:            c.Uint("retries"),
 		HeartbeatInterval:  c.Duration("heartbeat-interval"),
@@ -240,7 +246,7 @@ func loadCertPool(c *cli.Context, logger *logrus.Logger) (*x509.CertPool, error)
 		}
 	}
 
-	originCertPool, err := tlsconfig.LoadOriginCertPool(originCustomCAPool)
+	originCertPool, err := loadOriginCertPool(originCustomCAPool)
 	if err != nil {
 		return nil, errors.Wrap(err, "error loading the certificate pool")
 	}
@@ -253,6 +259,86 @@ func loadCertPool(c *cli.Context, logger *logrus.Logger) (*x509.CertPool, error)
 	return originCertPool, nil
 }
 
+func loadOriginCertPool(originCAPoolPEM []byte) (*x509.CertPool, error) {
+	// Get the global pool
+	certPool, err := loadGlobalCertPool()
+	if err != nil {
+		return nil, err
+	}
+
+	// Then, add any custom origin CA pool the user may have passed
+	if originCAPoolPEM != nil {
+		if !certPool.AppendCertsFromPEM(originCAPoolPEM) {
+			logger.Warn("could not append the provided origin CA to the cloudflared certificate pool")
+		}
+	}
+
+	return certPool, nil
+}
+
+func loadGlobalCertPool() (*x509.CertPool, error) {
+	// First, obtain the system certificate pool
+	certPool, err := x509.SystemCertPool()
+	if err != nil {
+		if runtime.GOOS != "windows" {
+			logger.WithError(err).Warn("error obtaining the system certificates")
+		}
+		certPool = x509.NewCertPool()
+	}
+
+	// Next, append the Cloudflare CAs into the system pool
+	cfRootCA, err := tlsconfig.GetCloudflareRootCA()
+	if err != nil {
+		return nil, errors.Wrap(err, "could not append Cloudflare Root CAs to cloudflared certificate pool")
+	}
+	for _, cert := range cfRootCA {
+		certPool.AddCert(cert)
+	}
+
+	// Finally, add the Hello certificate into the pool (since it's self-signed)
+	helloCert, err := tlsconfig.GetHelloCertificateX509()
+	if err != nil {
+		return nil, errors.Wrap(err, "could not append Hello server certificate to cloudflared certificate pool")
+	}
+	certPool.AddCert(helloCert)
+
+	return certPool, nil
+}
+
+func createTunnelConfig(c *cli.Context) (*tls.Config, error) {
+	var rootCAs []string
+	if c.String("cacert") != "" {
+		rootCAs = append(rootCAs, c.String("cacert"))
+	}
+	edgeAddrs := c.StringSlice("edge")
+
+	userConfig := &tlsconfig.TLSParameters{RootCAs: rootCAs}
+	tlsConfig, err := tlsconfig.GetConfig(userConfig)
+	if err != nil {
+		return nil, err
+	}
+	if tlsConfig.RootCAs == nil {
+		rootCAPool := x509.NewCertPool()
+		cfRootCA, err := tlsconfig.GetCloudflareRootCA()
+		if err != nil {
+			return nil, errors.Wrap(err, "could not append Cloudflare Root CAs to cloudflared certificate pool")
+		}
+		for _, cert := range cfRootCA {
+			rootCAPool.AddCert(cert)
+		}
+		tlsConfig.RootCAs = rootCAPool
+		tlsConfig.ServerName = "cftunnel.com"
+	} else if len(edgeAddrs) > 0 {
+		// Set for development environments and for testing specific origintunneld instances
+		tlsConfig.ServerName, _, _ = net.SplitHostPort(edgeAddrs[0])
+	}
+
+	if tlsConfig.ServerName == "" && !tlsConfig.InsecureSkipVerify {
+		return nil, fmt.Errorf("either ServerName or InsecureSkipVerify must be specified in the tls.Config")
+	}
+	return tlsConfig, nil
+}
+
 func isRunningFromTerminal() bool {
 	return terminal.IsTerminal(int(os.Stdout.Fd()))
 }

cmd/cloudflared/tunnel/configuration_test.go

@@ -0,0 +1,214 @@
+// +build ignore
+// TODO: Remove the above build tag and include this test when we start compiling with Golang 1.10.0+
+
+package tunnel
+
+import (
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/asn1"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// Generated using `openssl req -newkey rsa:512 -nodes -x509 -days 3650`
+var samplePEM = []byte(`
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
+`)
+
+var systemCertPoolSubjects []*pkix.Name
+
+type certificateFixture struct {
+	ou string
+	cn string
+}
+
+func TestMain(m *testing.M) {
+	systemCertPool, err := x509.SystemCertPool()
+	if isUnrecoverableError(err) {
+		os.Exit(1)
+	}
+
+	if systemCertPool == nil {
+		// On Windows, let's just assume the system cert pool was empty
+		systemCertPool = x509.NewCertPool()
+	}
+
+	systemCertPoolSubjects, err = getCertPoolSubjects(systemCertPool)
+	if err != nil {
+		os.Exit(1)
+	}
+
+	os.Exit(m.Run())
+}
+
+func TestLoadOriginCertPoolJustSystemPool(t *testing.T) {
+	certPoolSubjects := loadCertPoolSubjects(t, nil)
+	extraSubjects := subjectSubtract(systemCertPoolSubjects, certPoolSubjects)
+
+	// Remove extra subjects from the cert pool
+	var filteredSystemCertPoolSubjects []*pkix.Name
+
+	t.Log(extraSubjects)
+
+OUTER:
+	for _, subject := range certPoolSubjects {
+		for _, extraSubject := range extraSubjects {
+			if subject == extraSubject {
+				t.Log(extraSubject)
+				continue OUTER
+			}
+		}
+
+		filteredSystemCertPoolSubjects = append(filteredSystemCertPoolSubjects, subject)
+	}
+
+	assert.Equal(t, len(filteredSystemCertPoolSubjects), len(systemCertPoolSubjects))
+
+	difference := subjectSubtract(systemCertPoolSubjects, filteredSystemCertPoolSubjects)
+	assert.Equal(t, 0, len(difference))
+}
+
+func TestLoadOriginCertPoolCFCertificates(t *testing.T) {
+	certPoolSubjects := loadCertPoolSubjects(t, nil)
+
+	extraSubjects := subjectSubtract(systemCertPoolSubjects, certPoolSubjects)
+
+	expected := []*certificateFixture{
+		{ou: "CloudFlare Origin SSL ECC Certificate Authority"},
+		{ou: "CloudFlare Origin SSL Certificate Authority"},
+		{cn: "origin-pull.cloudflare.net"},
+		{cn: "Argo Tunnel Sample Hello Server Certificate"},
+	}
+
+	assertFixturesMatchSubjects(t, expected, extraSubjects)
+}
+
+func TestLoadOriginCertPoolWithExtraPEMs(t *testing.T) {
+	certPoolWithoutPEMSubjects := loadCertPoolSubjects(t, nil)
+	certPoolWithPEMSubjects := loadCertPoolSubjects(t, samplePEM)
+
+	difference := subjectSubtract(certPoolWithoutPEMSubjects, certPoolWithPEMSubjects)
+
+	assert.Equal(t, 2, len(difference))
+
+	expected := []*certificateFixture{
+		{cn: "Test One"},
+		{cn: "Test Two"},
+	}
+
+	assertFixturesMatchSubjects(t, expected, difference)
+}
+
+func loadCertPoolSubjects(t *testing.T, originCAPoolPEM []byte) []*pkix.Name {
+	certPool, err := loadOriginCertPool(originCAPoolPEM)
+	if isUnrecoverableError(err) {
+		t.Fatal(err)
+	}
+	assert.NotEmpty(t, certPool.Subjects())
+	certPoolSubjects, err := getCertPoolSubjects(certPool)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return certPoolSubjects
+}
+
+func assertFixturesMatchSubjects(t *testing.T, fixtures []*certificateFixture, subjects []*pkix.Name) {
+	assert.Equal(t, len(fixtures), len(subjects))
+
+	for _, fixture := range fixtures {
+		found := false
+		for _, subject := range subjects {
+			found = found || fixtureMatchesSubjectPredicate(fixture, subject)
+		}
+
+		if !found {
+			t.Fail()
+		}
+	}
+}
+
+func fixtureMatchesSubjectPredicate(fixture *certificateFixture, subject *pkix.Name) bool {
+	cnMatch := true
+	if fixture.cn != "" {
+		cnMatch = fixture.cn == subject.CommonName
+	}
+
+	ouMatch := true
+	if fixture.ou != "" {
+		ouMatch = len(subject.OrganizationalUnit) > 0 && fixture.ou == subject.OrganizationalUnit[0]
+	}
+
+	return cnMatch && ouMatch
+}
+
+func subjectSubtract(left []*pkix.Name, right []*pkix.Name) []*pkix.Name {
+	var difference []*pkix.Name
+
+	var found bool
+	for _, r := range right {
+		found = false
+		for _, l := range left {
+			if (*l).String() == (*r).String() {
+				found = true
+			}
+		}
+
+		if !found {
+			difference = append(difference, r)
+		}
+	}
+
+	return difference
+}
+
+func getCertPoolSubjects(certPool *x509.CertPool) ([]*pkix.Name, error) {
+	var subjects []*pkix.Name
+
+	for _, subject := range certPool.Subjects() {
+		var sequence pkix.RDNSequence
+		_, err := asn1.Unmarshal(subject, &sequence)
+		if err != nil {
+			return nil, err
+		}
+
+		name := pkix.Name{}
+		name.FillFromRDNSequence(&sequence)
+
+		subjects = append(subjects, &name)
+	}
+
+	return subjects, nil
+}
+
+func isUnrecoverableError(err error) bool {
+	return err != nil && err.Error() != "crypto/x509: system root pool is not available on Windows"
+}