Fix CA cert hash for root certs

pkg/clientaccess/token.go

@@ -15,6 +15,7 @@ import (
 	"time"
 
 	"github.com/pkg/errors"
+	certutil "github.com/rancher/dynamiclistener/cert"
 	"github.com/sirupsen/logrus"
 )
 
@@ -40,8 +41,7 @@ var (
 	}
 )
 
-type OverrideURLCallback func(config []byte) (*url.URL, error)
-
+// Info contains fields that track parsed parts of a cluster join token
 type Info struct {
 	CACerts  []byte `json:"cacerts,omitempty"`
 	BaseURL  string `json:"baseurl,omitempty"`
@@ -52,7 +52,8 @@ type Info struct {
 
 // String returns the token data, templated according to the token format
 func (i *Info) String() string {
-	return fmt.Sprintf(tokenFormat, tokenPrefix, hashCA(i.CACerts), i.Username, i.Password)
+	digest, _ := hashCA(i.CACerts)
+	return fmt.Sprintf(tokenFormat, tokenPrefix, digest, i.Username, i.Password)
 }
 
 // ParseAndValidateToken parses a token, downloads and validates the server's CA bundle,
@@ -70,7 +71,7 @@ func ParseAndValidateToken(server string, token string) (*Info, error) {
 	return info, nil
 }
 
-// ParseAndValidateToken parses a token with user override, downloads and
+// ParseAndValidateTokenForUser parses a token with user override, downloads and
 // validates the server's CA bundle, and validates it according to the caHash from the token if set.
 func ParseAndValidateTokenForUser(server, token, username string) (*Info, error) {
 	info, err := parseToken(token)
@@ -95,17 +96,49 @@ func (i *Info) setAndValidateServer(server string) error {
 	return i.validateCAHash()
 }
 
-// validateCACerts returns a boolean indicating whether or not a CA bundle matches the provided hash,
-// and a string containing the hash of the CA bundle.
+// validateCACerts returns a boolean indicating whether or not a CA bundle matches the
+// provided hash, and a string containing the hash of the CA bundle.
 func validateCACerts(cacerts []byte, hash string) (bool, string) {
-	newHash := hashCA(cacerts)
+	newHash, _ := hashCA(cacerts)
 	return hash == newHash, newHash
 }
 
-// hashCA returns the hex-encoded SHA256 digest of a byte array.
-func hashCA(cacerts []byte) string {
-	digest := sha256.Sum256(cacerts)
-	return hex.EncodeToString(digest[:])
+// hashCA returns the hex-encoded SHA256 digest of a CA bundle.
+// If the certificate bundle contains only a single certificate, a legacy hash is generated from
+// the literal bytes of the file; usually a PEM-encoded self-signed cluster CA certificate.
+// If the certificate bundle contains more than one certificate, the hash is instead generated
+// from the DER-encoded root certificate in the bundle. This allows for rotating or renewing the
+// cluster CA, as long as the root CA remains the same.
+func hashCA(b []byte) (string, error) {
+	certs, err := certutil.ParseCertsPEM(b)
+	if err != nil {
+		return "", err
+	}
+
+	if len(certs) > 1 {
+		// Bundle contains more than one cert; find the root for the first cert in the bundle and
+		// hash the DER of this, instead of just hashing the raw bytes of the whole file.
+		roots := x509.NewCertPool()
+		intermediates := x509.NewCertPool()
+		for i, cert := range certs {
+			if i > 0 {
+				if len(cert.AuthorityKeyId) == 0 || bytes.Equal(cert.AuthorityKeyId, cert.SubjectKeyId) {
+					roots.AddCert(cert)
+				} else {
+					intermediates.AddCert(cert)
+				}
+			}
+		}
+		if chains, err := certs[0].Verify(x509.VerifyOptions{Roots: roots, Intermediates: intermediates}); err == nil {
+			// It's possible but unlikely that there could be multiple valid chains back to a root
+			// certificate. Just use the first.
+			chain := chains[0]
+			b = chain[len(chain)-1].Raw
+		}
+	}
+
+	digest := sha256.Sum256(b)
+	return hex.EncodeToString(digest[:]), nil
 }
 
 // ParseUsernamePassword returns the username and password portion of a token string,
@@ -326,19 +359,24 @@ func put(u string, body []byte, client *http.Client, username, password string)
 	return nil
 }
 
-func FormatToken(token, certFile string) (string, error) {
-	if len(token) == 0 {
-		return token, nil
+// FormatToken takes a username:password string, and a path to a certificate bundle, and
+// returns a string containing the full K10 format token string. If the credentials are
+// empty, an empty token is returned. If the certificate bundle does not exist or does not
+// contain a valid bundle, an error is returned.
+func FormatToken(creds, certFile string) (string, error) {
+	if len(creds) == 0 {
+		return "", nil
 	}
 
-	certHash := ""
-	if len(certFile) > 0 {
-		b, err := os.ReadFile(certFile)
-		if err != nil {
-			return "", nil
-		}
-		digest := sha256.Sum256(b)
-		certHash = tokenPrefix + hex.EncodeToString(digest[:]) + "::"
+	b, err := os.ReadFile(certFile)
+	if err != nil {
+		return "", err
+	}
+
+	digest, err := hashCA(b)
+	if err != nil {
+		return "", err
 	}
-	return certHash + token, nil
+
+	return tokenPrefix + digest + "::" + creds, nil
 }

pkg/clientaccess/token_test.go

@@ -29,13 +29,14 @@ func Test_UnitTrustedCA(t *testing.T) {
 	assert := assert.New(t)
 	server := newTLSServer(t, defaultUsername, defaultPassword, false)
 	defer server.Close()
+	digest, _ := hashCA(getServerCA(server))
 
 	testInfo := &Info{
 		CACerts:  getServerCA(server),
 		BaseURL:  server.URL,
 		Username: defaultUsername,
 		Password: defaultPassword,
-		caHash:   hashCA(getServerCA(server)),
+		caHash:   digest,
 	}
 
 	testCases := []struct {
@@ -82,13 +83,14 @@ func Test_UnitUntrustedCA(t *testing.T) {
 	assert := assert.New(t)
 	server := newTLSServer(t, defaultUsername, defaultPassword, false)
 	defer server.Close()
+	digest, _ := hashCA(getServerCA(server))
 
 	testInfo := &Info{
 		CACerts:  getServerCA(server),
 		BaseURL:  server.URL,
 		Username: defaultUsername,
 		Password: defaultPassword,
-		caHash:   hashCA(getServerCA(server)),
+		caHash:   digest,
 	}
 
 	testCases := []struct {
@@ -140,6 +142,7 @@ func Test_UnitInvalidTokens(t *testing.T) {
 	assert := assert.New(t)
 	server := newTLSServer(t, defaultUsername, defaultPassword, false)
 	defer server.Close()
+	digest, _ := hashCA(getServerCA(server))
 
 	testCases := []struct {
 		server   string
@@ -153,7 +156,7 @@ func Test_UnitInvalidTokens(t *testing.T) {
 		{server.URL, "K10XX::x:y", "invalid token CA hash length"},
 		{server.URL,
 			"K10XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX::x:y",
-			"token CA hash does not match the Cluster CA certificate hash: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX != " + hashCA(getServerCA(server))},
+			"token CA hash does not match the Cluster CA certificate hash: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX != " + digest},
 	}
 
 	for _, testCase := range testCases {
@@ -172,13 +175,14 @@ func Test_UnitInvalidCredentials(t *testing.T) {
 	assert := assert.New(t)
 	server := newTLSServer(t, defaultUsername, defaultPassword, false)
 	defer server.Close()
+	digest, _ := hashCA(getServerCA(server))
 
 	testInfo := &Info{
 		CACerts:  getServerCA(server),
 		BaseURL:  server.URL,
 		Username: "nobody",
 		Password: "invalid",
-		caHash:   hashCA(getServerCA(server)),
+		caHash:   digest,
 	}
 
 	testCases := []string{
@@ -381,8 +385,14 @@ func newTLSServer(t *testing.T, username, password string, sendWrongCA bool) *ht
 
 // getServerCA returns a byte slice containing the PEM encoding of the server's CA certificate
 func getServerCA(server *httptest.Server) []byte {
-	certLen := len(server.TLS.Certificates)
-	return pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: server.TLS.Certificates[certLen-1].Certificate[0]})
+	bytes := []byte{}
+	for i, cert := range server.TLS.Certificates {
+		if i == 0 {
+			continue // Just return the chain, not the leaf server cert
+		}
+		bytes = append(bytes, pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: cert.Certificate[0]})...)
+	}
+	return bytes
 }
 
 // writeServerCA writes the PEM-encoded server certificate to a given path

pkg/daemons/control/deps/deps.go

 package deps
 
 import (
+	"bytes"
 	"crypto"
 	cryptorand "crypto/rand"
 	"crypto/sha256"
@@ -573,22 +574,7 @@ func fieldsChanged(certFile string, commonName string, organization []string, sa
 		return false
 	}
 
-	verifyOpts := x509.VerifyOptions{
-		Roots: x509.NewCertPool(),
-		KeyUsages: []x509.ExtKeyUsage{
-			x509.ExtKeyUsageAny,
-		},
-	}
-
-	for _, cert := range caCertificates {
-		verifyOpts.Roots.AddCert(cert)
-	}
-
-	if _, err := certificates[0].Verify(verifyOpts); err != nil {
-		return true
-	}
-
-	return false
+	return !bytes.Equal(certificates[0].AuthorityKeyId, caCertificates[0].SubjectKeyId)
 }
 
 func createClientCertKey(regen bool, commonName string, organization []string, altNames *certutil.AltNames, extKeyUsage []x509.ExtKeyUsage, caCertFile, caKeyFile, certFile, keyFile string) (bool, error) {