Implement FindCertificateChain function to find certificate chain

Certificate chain is found by following algorithm: * find first certificate either by id or/and label or/and serial (same as existing FindCertificate does); * if issuer is not nil, find next certificate by CKA_SUBJECT (issuer should be equal subject); * if certificate with required subject not found then read all certificates and try to find next certificate by AuthorityKeyId (AuthorityKeyId should be equal to SubjectKeyId); * finding stops if last found certificate is selfsigned (issuer is nil or equals to subject). Signed-off-by: Oleksandr Grytsov <oleksandr_grytsov@epam.com>
ThalesGroup · Feb 4, 2022 · 1bd9b57 · 1bd9b57
1 parent 5ef4a2e
commit 1bd9b57
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Showing 3 changed files with 195 additions and 9 deletions.
diff --git a/certificates.go b/certificates.go
@@ -22,6 +22,7 @@
 package crypto11
 
 import (
+	"bytes"
 	"crypto/tls"
 	"crypto/x509"
 	"encoding/asn1"
@@ -111,6 +112,67 @@ func findCertificatesWithAttributes(session *pkcs11Session, template []*pkcs11.A
 	return handles, nil
 }
 
+func findCertificateByKeyID(session *pkcs11Session, keyID []byte) (cert *x509.Certificate, err error) {
+	handles, err := findCertificatesWithAttributes(session, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, handle := range handles {
+		if cert, err = getX509Certificate(session, handle); err != nil {
+			return nil, err
+		}
+
+		if bytes.Equal(cert.SubjectKeyId, keyID) {
+			return cert, nil
+		}
+	}
+
+	return nil, errors.New("no certificate with required subject key ID found")
+}
+
+func findCertificateChain(session *pkcs11Session, cert *x509.Certificate) (certs []*x509.Certificate, err error) {
+	if len(cert.RawIssuer) == 0 || bytes.Equal(cert.RawIssuer, cert.RawSubject) {
+		return nil, nil
+	}
+
+	template := []*pkcs11.Attribute{pkcs11.NewAttribute(pkcs11.CKA_SUBJECT, cert.RawIssuer)}
+
+	handles, err := findCertificatesWithAttributes(session, template)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(handles) == 0 {
+		if cert, err = findCertificateByKeyID(session, cert.AuthorityKeyId); err != nil {
+			return nil, err
+		}
+	} else {
+		if cert, err = getX509Certificate(session, handles[0]); err != nil {
+			return nil, err
+		}
+	}
+
+	for _, foundCert := range certs {
+		if bytes.Equal(cert.RawSubject, foundCert.RawSubject) {
+			return certs, nil
+		}
+	}
+
+	certs = append(certs, cert)
+
+	certChain, err := findCertificateChain(session, cert)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(certChain) != 0 {
+		certs = append(certs, certChain...)
+	}
+
+	return certs, nil
+}
+
 // FindCertificate retrieves a previously imported certificate. Any combination of id, label
 // and serial can be provided. An error is return if all are nil.
 func (c *Context) FindCertificate(id []byte, label []byte, serial *big.Int) (*x509.Certificate, error) {
@@ -128,6 +190,42 @@ func (c *Context) FindCertificate(id []byte, label []byte, serial *big.Int) (*x5
 	return cert, err
 }
 
+// FindCertificateChain retrieves a previously imported certificate chain. Any combination of id, label
+// and serial can be provided. An error is return if all are nil.
+func (c *Context) FindCertificateChain(id []byte, label []byte, serial *big.Int) (certs []*x509.Certificate, err error) {
+	if c.closed.Get() {
+		return nil, errClosed
+	}
+
+	err = c.withSession(func(session *pkcs11Session) (err error) {
+		cert, err := findCertificate(session, id, label, serial)
+		if err != nil {
+			return err
+		}
+
+		if cert == nil {
+			return nil
+		}
+
+		certs = append(certs, cert)
+
+		certChain, err := findCertificateChain(session, cert)
+		if err != nil {
+			return err
+		}
+
+		if len(certChain) == 0 {
+			return nil
+		}
+
+		certs = append(certs, certChain...)
+
+		return nil
+	})
+
+	return certs, err
+}
+
 func (c *Context) FindAllPairedCertificates() (certificates []tls.Certificate, err error) {
 	if c.closed.Get() {
 		return nil, errClosed

diff --git a/certificates_test.go b/certificates_test.go
@@ -48,7 +48,7 @@ func TestCertificate(t *testing.T) {
 	id := randomBytes()
 	label := randomBytes()
 
-	cert := generateRandomCert(t)
+	cert := generateRandomCert(t, nil, "Foo", nil, nil)
 
 	err = ctx.ImportCertificateWithLabel(id, label, cert)
 	require.NoError(t, err)
@@ -81,7 +81,7 @@ func TestCertificateAttributes(t *testing.T) {
 		require.NoError(t, ctx.Close())
 	}()
 
-	cert := generateRandomCert(t)
+	cert := generateRandomCert(t, nil, "Foo", nil, nil)
 
 	// We import this with a different serial number, to test this is obeyed
 	ourSerial := new(big.Int)
@@ -116,7 +116,7 @@ func TestCertificateRequiredArgs(t *testing.T) {
 		require.NoError(t, ctx.Close())
 	}()
 
-	cert := generateRandomCert(t)
+	cert := generateRandomCert(t, nil, "Foo", nil, nil)
 
 	val := randomBytes()
 
@@ -143,7 +143,7 @@ func TestDeleteCertificate(t *testing.T) {
 	randomCert := func() ([]byte, []byte, *x509.Certificate) {
 		id := randomBytes()
 		label := randomBytes()
-		cert := generateRandomCert(t)
+		cert := generateRandomCert(t, nil, "Foo", nil, nil)
 		return id, label, cert
 	}
 	importCertificate := func() ([]byte, []byte, *big.Int) {
@@ -207,14 +207,98 @@ func TestDeleteCertificate(t *testing.T) {
 	require.Nil(t, cert)
 }
 
-func generateRandomCert(t *testing.T) *x509.Certificate {
+func TestCertificateChain(t *testing.T) {
+	skipTest(t, skipTestCert)
+
+	ctx, err := ConfigureFromFile("config")
+	require.NoError(t, err)
+
+	defer func() {
+		require.NoError(t, ctx.Close())
+	}()
+
+	certNames := []string{"Cert0", "Cert1", "Cert2"}
+
+	var (
+		parent                       *x509.Certificate
+		originCertChain              []*x509.Certificate
+		authorityKeyId, subjectKeyID []byte
+		ids                          [][]byte
+	)
+
+	for _, name := range certNames {
+		subjectKeyID = randomBytes()
+
+		cert := generateRandomCert(t, parent, name, authorityKeyId, subjectKeyID)
+
+		id := randomBytes()
+		ids = append([][]byte{id}, ids...)
+
+		err = ctx.ImportCertificate(id, cert)
+		require.NoError(t, err)
+
+		originCertChain = append([]*x509.Certificate{cert}, originCertChain...)
+
+		parent = cert
+		authorityKeyId = subjectKeyID
+	}
+
+	foundCertChain, err := ctx.FindCertificateChain(ids[0], nil, nil)
+	require.NoError(t, err)
+	require.NotNil(t, foundCertChain)
+
+	assert.Equal(t, len(foundCertChain), len(originCertChain))
+
+	for i := 0; i < len(foundCertChain); i++ {
+		assert.Equal(t, foundCertChain[i].Signature, originCertChain[i].Signature)
+	}
+
+	err = ctx.DeleteCertificate(ids[len(ids)-1], nil, nil)
+	require.NoError(t, err)
+
+	oldCert := originCertChain[len(originCertChain)-1]
+	newCert := generateRandomCert(t, nil, "NewCert", oldCert.AuthorityKeyId, oldCert.SubjectKeyId)
+
+	originCertChain[len(originCertChain)-1] = newCert
+
+	id := randomBytes()
+
+	err = ctx.ImportCertificate(id, newCert)
+	require.NoError(t, err)
+
+	ids[len(ids)-1] = id
+
+	foundCertChain, err = ctx.FindCertificateChain(ids[0], nil, nil)
+	require.NoError(t, err)
+	require.NotNil(t, foundCertChain)
+
+	assert.Equal(t, len(foundCertChain), len(originCertChain))
+
+	for i := 0; i < len(foundCertChain); i++ {
+		assert.Equal(t, foundCertChain[i].Signature, originCertChain[i].Signature)
+	}
+
+	for _, id := range ids {
+		err = ctx.DeleteCertificate(id, nil, nil)
+		require.NoError(t, err)
+	}
+
+	foundCertChain, err = ctx.FindCertificateChain([]byte("test2"), nil, nil)
+	require.NoError(t, err)
+	assert.Nil(t, foundCertChain)
+}
+
+func generateRandomCert(t *testing.T, parent *x509.Certificate, commonName string,
+	authorityKeyId, subjectKeyID []byte) *x509.Certificate {
 	serial, err := rand.Int(rand.Reader, big.NewInt(20000))
 	require.NoError(t, err)
 
-	ca := &x509.Certificate{
+	template := &x509.Certificate{
 		Subject: pkix.Name{
-			CommonName: "Foo",
+			CommonName: commonName,
 		},
+		AuthorityKeyId:        authorityKeyId,
+		SubjectKeyId:          subjectKeyID,
 		SerialNumber:          serial,
 		NotAfter:              time.Now().Add(365 * 24 * time.Hour),
 		IsCA:                  true,
@@ -223,11 +307,15 @@ func generateRandomCert(t *testing.T) *x509.Certificate {
 		BasicConstraintsValid: true,
 	}
 
+	if parent == nil {
+		parent = template
+	}
+
 	key, err := rsa.GenerateKey(rand.Reader, 4096)
 	require.NoError(t, err)
 
 	csr := &key.PublicKey
-	certBytes, err := x509.CreateCertificate(rand.Reader, ca, ca, csr, key)
+	certBytes, err := x509.CreateCertificate(rand.Reader, template, parent, csr, key)
 	require.NoError(t, err)
 
 	cert, err := x509.ParseCertificate(certBytes)

diff --git a/close_test.go b/close_test.go
@@ -85,7 +85,7 @@ func TestErrorAfterClosed(t *testing.T) {
 	_, err = ctx.NewRandomReader()
 	assert.Equal(t, errClosed, err)
 
-	cert := generateRandomCert(t)
+	cert := generateRandomCert(t, nil, "Foo", nil, nil)
 
 	err = ctx.ImportCertificate(bytes, cert)
 	assert.Equal(t, errClosed, err)