[Security] Add support for SPIFFE Bundle Maps in XDS bundles

credentials/tls/certprovider/pemfile/builder.go

@@ -63,19 +63,21 @@ func pluginConfigFromJSON(jd json.RawMessage) (Options, error) {
 	// is that the refresh_interval is represented here as a duration proto,
 	// while in the latter a time.Duration is used.
 	cfg := &struct {
-		CertificateFile   string          `json:"certificate_file,omitempty"`
-		PrivateKeyFile    string          `json:"private_key_file,omitempty"`
-		CACertificateFile string          `json:"ca_certificate_file,omitempty"`
-		RefreshInterval   json.RawMessage `json:"refresh_interval,omitempty"`
+		CertificateFile          string          `json:"certificate_file,omitempty"`
+		PrivateKeyFile           string          `json:"private_key_file,omitempty"`
+		CACertificateFile        string          `json:"ca_certificate_file,omitempty"`
+		SPIFFETrustBundleMapFile string          `json:"spiffe_trust_bundle_map_file,omitempty"`
+		RefreshInterval          json.RawMessage `json:"refresh_interval,omitempty"`
 	}{}
 	if err := json.Unmarshal(jd, cfg); err != nil {
 		return Options{}, fmt.Errorf("pemfile: json.Unmarshal(%s) failed: %v", string(jd), err)
 	}
 
 	opts := Options{
-		CertFile: cfg.CertificateFile,
-		KeyFile:  cfg.PrivateKeyFile,
-		RootFile: cfg.CACertificateFile,
+		CertFile:            cfg.CertificateFile,
+		KeyFile:             cfg.PrivateKeyFile,
+		RootFile:            cfg.CACertificateFile,
+		SPIFFEBundleMapFile: cfg.SPIFFETrustBundleMapFile,
 		// Refresh interval is the only field in the configuration for which we
 		// support a default value. We cannot possibly have valid defaults for
 		// file paths to watch. Also, it is valid to specify an empty path for

credentials/tls/certprovider/pemfile/watcher.go

@@ -115,7 +115,7 @@ func newProvider(o Options) certprovider.Provider {
 	if o.CertFile != "" && o.KeyFile != "" {
 		provider.identityDistributor = newDistributor()
 	}
-	if o.RootFile != "" {
+	if o.RootFile != "" || o.SPIFFEBundleMapFile != "" {
 		provider.rootDistributor = newDistributor()
 	}
 

internal/credentials/spiffe/spiffe.go

@@ -22,6 +22,7 @@
 package spiffe
 
 import (
+	"crypto/x509"
 	"encoding/json"
 	"fmt"
 
@@ -61,3 +62,46 @@ func BundleMapFromBytes(bundleMapBytes []byte) (map[string]*spiffebundle.Bundle,
 	}
 	return bundleMap, nil
 }
+
+// GetRootsFromSPIFFEBundleMap returns the root trust certificates from the
+// SPIFFE bundle map for the given trust domain from the leaf certificate.
+func GetRootsFromSPIFFEBundleMap(bundleMap map[string]*spiffebundle.Bundle, leafCert *x509.Certificate) (*x509.CertPool, error) {
+	// 1. Upon receiving a peer certificate, verify that it is a well-formed SPIFFE
+	//    leaf certificate.  In particular, it must have a single URI SAN containing
+	//    a well-formed SPIFFE ID ([SPIFFE ID format]).
+	spiffeID, err := idFromCert(leafCert)
+	if err != nil {
+		return nil, fmt.Errorf("spiffe: could not get spiffe ID from peer leaf cert but verification with spiffe trust map was configured: %v", err)
+	}
+
+	// 2. Use the trust domain in the peer certificate's SPIFFE ID to lookup
+	//    the SPIFFE trust bundle. If the trust domain is not contained in the
+	//    configured trust map, reject the certificate.
+	spiffeBundle, ok := bundleMap[spiffeID.TrustDomain().Name()]
+	if !ok {
+		return nil, fmt.Errorf("spiffe: no bundle found for peer certificates trust domain %q but verification with a SPIFFE trust map was configured", spiffeID.TrustDomain().Name())
+	}
+	roots := spiffeBundle.X509Authorities()
+	rootPool := x509.NewCertPool()
+	for _, root := range roots {
+		rootPool.AddCert(root)
+	}
+	return rootPool, nil
+}
+
+// idFromCert parses the SPIFFE ID from the x509.Certificate. If the certificate
+// does not have a valid SPIFFE ID, returns an error.
+func idFromCert(cert *x509.Certificate) (*spiffeid.ID, error) {
+	if cert == nil {
+		return nil, fmt.Errorf("input cert is nil")
+	}
+	// A valid SPIFFE Certificate should have exactly one URI.
+	if len(cert.URIs) != 1 {
+		return nil, fmt.Errorf("input cert has %v URIs but should have 1", len(cert.URIs))
+	}
+	id, err := spiffeid.FromURI(cert.URIs[0])
+	if err != nil {
+		return nil, fmt.Errorf("invalid spiffeid: %v", err)
+	}
+	return &id, nil
+}

internal/credentials/spiffe/spiffe_test.go

@@ -22,51 +22,49 @@ import (
 	"crypto/x509"
 	"encoding/pem"
 	"io"
+	"net/url"
 	"os"
+	"strings"
 	"testing"
 
-	"github.com/spiffe/go-spiffe/v2/bundle/spiffebundle"
 	"google.golang.org/grpc/testdata"
 )
 
-// loadSPIFFEBundleMap loads a SPIFFE Bundle Map from a file. See the SPIFFE
-// Bundle Map spec for more detail -
-// https://github.com/spiffe/spiffe/blob/main/standards/SPIFFE_Trust_Domain_and_Bundle.md#4-spiffe-bundle-format
-// If duplicate keys are encountered in the JSON parsing, Go's default unmarshal
-// behavior occurs which causes the last processed entry to be the entry in the
-// parsed map.
-func loadSPIFFEBundleMap(filePath string) (map[string]*spiffebundle.Bundle, error) {
-	bundleMapRaw, err := os.ReadFile(filePath)
+const wantURI = "spiffe://foo.bar.com/client/workload/1"
+
+func loadFileBytes(t *testing.T, filePath string) []byte {
+	bytes, err := os.ReadFile(filePath)
 	if err != nil {
-		return nil, err
+		t.Fatalf("Error reading file: %v", err)
 	}
-	return BundleMapFromBytes(bundleMapRaw)
+	return bytes
 }
 
 func TestKnownSPIFFEBundle(t *testing.T) {
 	spiffeBundleFile := testdata.Path("spiffe/spiffebundle.json")
-	bundles, err := loadSPIFFEBundleMap(spiffeBundleFile)
+	spiffeBundleBytes := loadFileBytes(t, spiffeBundleFile)
+	bundles, err := BundleMapFromBytes(spiffeBundleBytes)
 	if err != nil {
-		t.Fatalf("LoadSPIFFEBundleMap(%v) Error during parsing: %v", spiffeBundleFile, err)
+		t.Fatalf("BundleMapFromBytes(%v) error during parsing: %v", spiffeBundleFile, err)
 	}
-	wantBundleSize := 2
+	const wantBundleSize = 2
 	if len(bundles) != wantBundleSize {
-		t.Fatalf("LoadSPIFFEBundleMap(%v) did not parse correct bundle length. got %v want %v", spiffeBundleFile, len(bundles), wantBundleSize)
+		t.Fatalf("BundleMapFromBytes(%v) did not parse correct bundle length. got %v want %v", spiffeBundleFile, len(bundles), wantBundleSize)
 	}
 	if bundles["example.com"] == nil {
-		t.Fatalf("LoadSPIFFEBundleMap(%v) got no bundle for example.com", spiffeBundleFile)
+		t.Fatalf("BundleMapFromBytes(%v) got no bundle for example.com", spiffeBundleFile)
 	}
 	if bundles["test.example.com"] == nil {
-		t.Fatalf("LoadSPIFFEBundleMap(%v) got no bundle for test.example.com", spiffeBundleFile)
+		t.Fatalf("BundleMapFromBytes(%v) got no bundle for test.example.com", spiffeBundleFile)
 	}
 
-	expectedExampleComCert := loadX509Cert(t, testdata.Path("spiffe/spiffe_cert.pem"))
-	expectedTestExampleComCert := loadX509Cert(t, testdata.Path("spiffe/server1_spiffe.pem"))
-	if !bundles["example.com"].X509Authorities()[0].Equal(expectedExampleComCert) {
-		t.Fatalf("LoadSPIFFEBundleMap(%v) parsed wrong cert for example.com.", spiffeBundleFile)
+	wantExampleComCert := loadX509Cert(t, testdata.Path("spiffe/spiffe_cert.pem"))
+	wantTestExampleComCert := loadX509Cert(t, testdata.Path("spiffe/server1_spiffe.pem"))
+	if !bundles["example.com"].X509Authorities()[0].Equal(wantExampleComCert) {
+		t.Errorf("BundleMapFromBytes(%v) parsed wrong cert for example.com.", spiffeBundleFile)
 	}
-	if !bundles["test.example.com"].X509Authorities()[0].Equal(expectedTestExampleComCert) {
-		t.Fatalf("LoadSPIFFEBundleMap(%v) parsed wrong cert for test.example.com", spiffeBundleFile)
+	if !bundles["test.example.com"].X509Authorities()[0].Equal(wantTestExampleComCert) {
+		t.Errorf("BundleMapFromBytes(%v) parsed wrong cert for test.example.com", spiffeBundleFile)
 	}
 
 }
@@ -86,7 +84,7 @@ func loadX509Cert(t *testing.T, filePath string) *x509.Certificate {
 	return cert
 }
 
-func TestLoadSPIFFEBundleMapFailures(t *testing.T) {
+func TestSPIFFEBundleMapFailures(t *testing.T) {
 	filePaths := []string{
 		testdata.Path("spiffe/spiffebundle_corrupted_cert.json"),
 		testdata.Path("spiffe/spiffebundle_malformed.json"),
@@ -95,28 +93,154 @@ func TestLoadSPIFFEBundleMapFailures(t *testing.T) {
 		testdata.Path("spiffe/spiffebundle_wrong_multi_certs.json"),
 		testdata.Path("spiffe/spiffebundle_wrong_root.json"),
 		testdata.Path("spiffe/spiffebundle_wrong_seq_type.json"),
-		testdata.Path("NOT_A_REAL_FILE"),
 		testdata.Path("spiffe/spiffebundle_invalid_trustdomain.json"),
+		testdata.Path("spiffe/spiffebundle_empty_string_key.json"),
+		testdata.Path("spiffe/spiffebundle_empty_keys.json"),
 	}
 	for _, path := range filePaths {
 		t.Run(path, func(t *testing.T) {
-			if _, err := loadSPIFFEBundleMap(path); err == nil {
-				t.Fatalf("LoadSPIFFEBundleMap(%v) did not fail but should have.", path)
+			bundleBytes := loadFileBytes(t, path)
+			if _, err := BundleMapFromBytes(bundleBytes); err == nil {
+				t.Fatalf("BundleMapFromBytes(%v) did not fail but should have", path)
 			}
 		})
 	}
 }
 
-func TestLoadSPIFFEBundleMapX509Failures(t *testing.T) {
+func TestSPIFFEBundleMapX509Failures(t *testing.T) {
 	// SPIFFE Bundles only support a use of x509-svid and jwt-svid. If a
 	// use other than this is specified, the parser does not fail, it
 	// just doesn't add an x509 authority or jwt authority to the bundle
 	filePath := testdata.Path("spiffe/spiffebundle_wrong_use.json")
-	bundle, err := loadSPIFFEBundleMap(filePath)
+	bundleBytes := loadFileBytes(t, filePath)
+	bundle, err := BundleMapFromBytes(bundleBytes)
 	if err != nil {
-		t.Fatalf("LoadSPIFFEBundleMap(%v) failed with error: %v", filePath, err)
+		t.Fatalf("BundleMapFromBytes(%v) failed with error: %v", filePath, err)
 	}
 	if len(bundle["example.com"].X509Authorities()) != 0 {
-		t.Fatalf("LoadSPIFFEBundleMap(%v) did not have empty bundle but should have.", filePath)
+		t.Fatalf("BundleMapFromBytes(%v) did not have empty bundle but should have", filePath)
+	}
+}
+
+func TestGetRootsFromSPIFFEBundleMapSuccess(t *testing.T) {
+	bundleMapFile := testdata.Path("spiffe/spiffebundle_match_client_spiffe.json")
+	bundleBytes := loadFileBytes(t, bundleMapFile)
+	bundle, err := BundleMapFromBytes(bundleBytes)
+	if err != nil {
+		t.Fatalf("BundleMapFromBytes(%v) failed with error: %v", bundleMapFile, err)
+	}
+
+	cert := loadX509Cert(t, testdata.Path("spiffe/client_spiffe.pem"))
+	gotRoots, err := GetRootsFromSPIFFEBundleMap(bundle, cert)
+	if err != nil {
+		t.Fatalf("GetRootsFromSPIFFEBundleMap() failed with err %v", err)
+	}
+	wantRoot := loadX509Cert(t, testdata.Path("spiffe/spiffe_cert.pem"))
+	wantRoots := x509.NewCertPool()
+	wantRoots.AddCert(wantRoot)
+	if !gotRoots.Equal(wantRoots) {
+		t.Fatalf("GetRootsFromSPIFFEBundleMap() got %v want %v", gotRoots, wantRoots)
+	}
+}
+
+func TestGetRootsFromSPIFFEBundleMapFailures(t *testing.T) {
+	bundleMapFile := testdata.Path("spiffe/spiffebundle.json")
+	bundleBytes := loadFileBytes(t, bundleMapFile)
+	bundle, err := BundleMapFromBytes(bundleBytes)
+	certWithTwoURIs := loadX509Cert(t, testdata.Path("spiffe/client_spiffe.pem"))
+	certWithTwoURIs.URIs = append(certWithTwoURIs.URIs, certWithTwoURIs.URIs[0])
+	certWithNoURIs := loadX509Cert(t, testdata.Path("spiffe/client_spiffe.pem"))
+	certWithNoURIs.URIs = nil
+	if err != nil {
+		t.Fatalf("BundleMapFromBytes(%v) failed with error: %v", bundleMapFile, err)
+	}
+	tests := []struct {
+		name          string
+		bundleMapFile string
+		leafCert      *x509.Certificate
+		wantErr       string
+	}{
+		{
+			name:     "no bundle for peer cert spiffeID",
+			leafCert: loadX509Cert(t, testdata.Path("spiffe/client_spiffe.pem")),
+			wantErr:  "no bundle found for peer certificates",
+		},
+		{
+			name:     "cert has invalid SPIFFE id",
+			leafCert: loadX509Cert(t, testdata.Path("ca.pem")),
+			wantErr:  "could not get spiffe ID from peer leaf cert",
+		},
+		{
+			name:     "nil cert",
+			leafCert: nil,
+			wantErr:  "input cert is nil",
+		},
+		{
+			name:     "cert has multiple URIs",
+			leafCert: certWithTwoURIs,
+			wantErr:  "input cert has 2 URIs but should have 1",
+		},
+		{
+			name:     "cert has no URIs",
+			leafCert: certWithNoURIs,
+			wantErr:  "input cert has 0 URIs but should have 1",
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			_, err = GetRootsFromSPIFFEBundleMap(bundle, tc.leafCert)
+			if err == nil {
+				t.Fatalf("GetRootsFromSPIFFEBundleMap() got no error but want error containing %v.", tc.wantErr)
+			}
+			if !strings.Contains(err.Error(), tc.wantErr) {
+				t.Fatalf("GetRootsFromSPIFFEBundleMap() got error: %v. want error to contain %v", err, tc.wantErr)
+			}
+		})
+	}
+}
+
+func TestIDFromCert(t *testing.T) {
+	cert := loadX509Cert(t, testdata.Path("x509/spiffe_cert.pem"))
+	uri, err := idFromCert(cert)
+	if err != nil {
+		t.Fatalf("idFromCert() failed with err: %v", err)
+	}
+	if uri != nil && uri.String() != wantURI {
+		t.Fatalf("ID not expected, got %s, want %s", uri.String(), wantURI)
+	}
+}
+
+func TestIDFromCertFileFailures(t *testing.T) {
+	certWithNoURIs := loadX509Cert(t, testdata.Path("spiffe/client_spiffe.pem"))
+	certWithNoURIs.URIs = nil
+	certWithInvalidSPIFFEID := loadX509Cert(t, testdata.Path("spiffe/client_spiffe.pem"))
+	certWithInvalidSPIFFEID.URIs = []*url.URL{{Path: "non-spiffe.bad"}}
+	tests := []struct {
+		name string
+		cert *x509.Certificate
+	}{
+		{
+			name: "certificate with multiple URIs",
+			cert: loadX509Cert(t, testdata.Path("x509/multiple_uri_cert.pem")),
+		},
+		{
+			name: "certificate with invalidSPIFFE ID",
+			cert: certWithInvalidSPIFFEID,
+		},
+		{
+			name: "nil cert",
+			cert: nil,
+		},
+		{
+			name: "cert with no URIs",
+			cert: certWithNoURIs,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if _, err := idFromCert(tt.cert); err == nil {
+				t.Fatalf("idFromCert() succeeded but want error")
+			}
+		})
 	}
 }