do not panic when loading a V2 CA certificate, but don't try to use i…

…t either

cert/ca.go

@@ -30,11 +30,15 @@ func NewCAPoolFromBytes(caPEMs []byte) (*NebulaCAPool, error) {
 	pool := NewCAPool()
 	var err error
 	var expired bool
+	var caTooNew bool
 	for {
 		caPEMs, err = pool.AddCACertificate(caPEMs)
 		if errors.Is(err, ErrExpired) {
 			expired = true
 			err = nil
+		} else if errors.Is(err, ErrInvalidPEMCertificateUnsupported) {
+			caTooNew = true
+			err = nil
 		}
 		if err != nil {
 			return nil, err
@@ -46,6 +50,8 @@ func NewCAPoolFromBytes(caPEMs []byte) (*NebulaCAPool, error) {
 
 	if expired {
 		return pool, ErrExpired
+	} else if caTooNew {
+		return pool, ErrInvalidPEMCertificateUnsupported
 	}
 
 	return pool, nil

cert/cert.go

@@ -28,6 +28,7 @@ const publicKeyLen = 32
 
 const (
 	CertBanner                       = "NEBULA CERTIFICATE"
+	CertificateV2Banner              = "NEBULA CERTIFICATE V2"
 	X25519PrivateKeyBanner           = "NEBULA X25519 PRIVATE KEY"
 	X25519PublicKeyBanner            = "NEBULA X25519 PUBLIC KEY"
 	EncryptedEd25519PrivateKeyBanner = "NEBULA ED25519 ENCRYPTED PRIVATE KEY"
@@ -163,6 +164,9 @@ func UnmarshalNebulaCertificateFromPEM(b []byte) (*NebulaCertificate, []byte, er
 	if p == nil {
 		return nil, r, fmt.Errorf("input did not contain a valid PEM encoded block")
 	}
+	if p.Type == CertificateV2Banner {
+		return nil, r, ErrInvalidPEMCertificateUnsupported
+	}
 	if p.Type != CertBanner {
 		return nil, r, fmt.Errorf("bytes did not contain a proper nebula certificate banner")
 	}

cert/cert_test.go

@@ -572,6 +572,13 @@ CmYKEG5lYnVsYSBQMjU2IHRlc3Qo4s+7mgYw4tXrsAc6QQRkaW2jFmllYvN4+/k2
 76gvQAGgBgESRzBFAiEAib0/te6eMiZOKD8gdDeloMTS0wGuX2t0C7TFdUhAQzgC
 IBNWYMep3ysx9zCgknfG5dKtwGTaqF++BWKDYdyl34KX
 -----END NEBULA CERTIFICATE-----
+`
+
+	v2 := `
+# valid PEM with the V2 header
+-----BEGIN NEBULA CERTIFICATE V2-----
+CmYKEG5lYnVsYSBQMjU2IHRlc3Qo4s+7mgYw4tXrsAc6QQRkaW2jFmllYvN4+/k2
+-----END NEBULA CERTIFICATE V2-----
 `
 
 	rootCA := NebulaCertificate{
@@ -619,6 +626,11 @@ IBNWYMep3ysx9zCgknfG5dKtwGTaqF++BWKDYdyl34KX
 	assert.Nil(t, err)
 	assert.Equal(t, ppppp.CAs[string("a7938893ec8c4ef769b06d7f425e5e46f7a7f5ffa49c3bcf4a86b608caba9159")].Details.Name, rootCAP256.Details.Name)
 	assert.Equal(t, len(ppppp.CAs), 1)
+
+	pppppp, err := NewCAPoolFromBytes(append([]byte(p256), []byte(v2)...))
+	assert.Equal(t, err, ErrInvalidPEMCertificateUnsupported)
+	assert.Equal(t, pppppp.CAs[string("a7938893ec8c4ef769b06d7f425e5e46f7a7f5ffa49c3bcf4a86b608caba9159")].Details.Name, rootCAP256.Details.Name)
+	assert.Equal(t, len(pppppp.CAs), 1)
 }
 
 func appendByteSlices(b ...[]byte) []byte {

cert/errors.go

@@ -5,10 +5,11 @@ import (
 )
 
 var (
-	ErrRootExpired       = errors.New("root certificate is expired")
-	ErrExpired           = errors.New("certificate is expired")
-	ErrNotCA             = errors.New("certificate is not a CA")
-	ErrNotSelfSigned     = errors.New("certificate is not self-signed")
-	ErrBlockListed       = errors.New("certificate is in the block list")
-	ErrSignatureMismatch = errors.New("certificate signature did not match")
+	ErrRootExpired                      = errors.New("root certificate is expired")
+	ErrExpired                          = errors.New("certificate is expired")
+	ErrNotCA                            = errors.New("certificate is not a CA")
+	ErrNotSelfSigned                    = errors.New("certificate is not self-signed")
+	ErrBlockListed                      = errors.New("certificate is in the block list")
+	ErrSignatureMismatch                = errors.New("certificate signature did not match")
+	ErrInvalidPEMCertificateUnsupported = errors.New("bytes contain an unsupported certificate format")
 )

pki.go

@@ -237,6 +237,8 @@ func loadCAPoolFromConfig(l *logrus.Logger, c *config.C) (*cert.NebulaCAPool, er
 			return nil, errors.New("no valid CA certificates present")
 		}
 
+	} else if errors.Is(err, cert.ErrInvalidPEMCertificateUnsupported) {
+		l.WithError(err).Warn("At least one configured CA is unsupported by this version of nebula. It has been ignored.")
 	} else if err != nil {
 		return nil, fmt.Errorf("error while adding CA certificate to CA trust store: %s", err)
 	}