snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

internal/credentials/spiffe/spiffe.go

@@ -0,0 +1,107 @@
+/*
+ *
+ * Copyright 2025 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package spiffe defines APIs for working with SPIFFE Bundle Maps.
+//
+// All APIs in this package are experimental.
+package spiffe
+
+import (
+	"crypto/x509"
+	"encoding/json"
+	"fmt"
+
+	"github.com/spiffe/go-spiffe/v2/bundle/spiffebundle"
+	"github.com/spiffe/go-spiffe/v2/spiffeid"
+)
+
+type partialParsedSPIFFEBundleMap struct {
+	Bundles map[string]json.RawMessage `json:"trust_domains"`
+}
+
+// BundleMapFromBytes parses bytes into a SPIFFE Bundle Map. 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 BundleMapFromBytes(bundleMapBytes []byte) (map[string]*spiffebundle.Bundle, error) {
+	var result partialParsedSPIFFEBundleMap
+	if err := json.Unmarshal(bundleMapBytes, &result); err != nil {
+		return nil, err
+	}
+	if result.Bundles == nil {
+		return nil, fmt.Errorf("spiffe: BundleMapFromBytes() no bundles parsed from spiffe bundle map bytes")
+	}
+	bundleMap := map[string]*spiffebundle.Bundle{}
+	for td, jsonBundle := range result.Bundles {
+		trustDomain, err := spiffeid.TrustDomainFromString(td)
+		if err != nil {
+			return nil, fmt.Errorf("spiffe: BundleMapFromBytes() invalid trust domain %q found when parsing SPIFFE Bundle Map: %v", td, err)
+		}
+		bundle, err := spiffebundle.Parse(trustDomain, jsonBundle)
+		if err != nil {
+			return nil, fmt.Errorf("spiffe: BundleMapFromBytes() failed to parse bundle for trust domain %q: %v", td, err)
+		}
+		bundleMap[td] = 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
+}