IDForwarding: Add service and a local signer (#75423)

* IDForwarding: Add service for handling id token and create a local signer
---------

Co-authored-by: Ieva <ieva.vasiljeva@grafana.com>

pkg/server/wire.go

@@ -43,6 +43,8 @@ import (
 	"github.com/grafana/grafana/pkg/services/annotations/annotationsimpl"
 	"github.com/grafana/grafana/pkg/services/anonymous/anonimpl/anonstore"
 	"github.com/grafana/grafana/pkg/services/apikey/apikeyimpl"
+	"github.com/grafana/grafana/pkg/services/auth"
+	"github.com/grafana/grafana/pkg/services/auth/idimpl"
 	"github.com/grafana/grafana/pkg/services/auth/jwt"
 	"github.com/grafana/grafana/pkg/services/authn/authnimpl"
 	"github.com/grafana/grafana/pkg/services/cleanup"
@@ -361,6 +363,8 @@ var wireBasicSet = wire.NewSet(
 	loggermw.Provide,
 	signingkeysimpl.ProvideEmbeddedSigningKeysService,
 	wire.Bind(new(signingkeys.Service), new(*signingkeysimpl.Service)),
+	idimpl.ProvideService,
+	wire.Bind(new(auth.IDService), new(*idimpl.Service)),
 	grafanaapiserver.WireSet,
 	apiregistry.WireSet,
 )

pkg/server/wireexts_oss.go

@@ -18,6 +18,7 @@ import (
 	"github.com/grafana/grafana/pkg/services/anonymous/anonimpl"
 	"github.com/grafana/grafana/pkg/services/auth"
 	"github.com/grafana/grafana/pkg/services/auth/authimpl"
+	"github.com/grafana/grafana/pkg/services/auth/idimpl"
 	"github.com/grafana/grafana/pkg/services/caching"
 	"github.com/grafana/grafana/pkg/services/datasources/guardian"
 	"github.com/grafana/grafana/pkg/services/encryption"
@@ -91,6 +92,8 @@ var wireExtsBasicSet = wire.NewSet(
 	wire.Bind(new(caching.CachingService), new(*caching.OSSCachingService)),
 	secretsMigrator.ProvideSecretsMigrator,
 	wire.Bind(new(secrets.Migrator), new(*secretsMigrator.SecretsMigrator)),
+	idimpl.ProvideLocalSigner,
+	wire.Bind(new(auth.IDSigner), new(*idimpl.LocalSigner)),
 )
 
 var wireExtsSet = wire.NewSet(

pkg/services/auth/id.go

@@ -0,0 +1,21 @@
+package auth
+
+import (
+	"context"
+
+	"github.com/go-jose/go-jose/v3/jwt"
+	"github.com/grafana/grafana/pkg/services/auth/identity"
+)
+
+type IDService interface {
+	// SignIdentity signs a id token for provided identity that can be forwarded to plugins and external services
+	SignIdentity(ctx context.Context, identity identity.Requester) (string, error)
+}
+
+type IDSigner interface {
+	SignIDToken(ctx context.Context, claims *IDClaims) (string, error)
+}
+
+type IDClaims struct {
+	jwt.Claims
+}

pkg/services/auth/idimpl/service.go

@@ -0,0 +1,74 @@
+package idimpl
+
+import (
+	"context"
+	"fmt"
+	"strconv"
+	"time"
+
+	"github.com/go-jose/go-jose/v3/jwt"
+	"github.com/grafana/grafana/pkg/infra/log"
+	"github.com/grafana/grafana/pkg/infra/remotecache"
+	"github.com/grafana/grafana/pkg/services/auth"
+	"github.com/grafana/grafana/pkg/services/auth/identity"
+	"github.com/grafana/grafana/pkg/setting"
+)
+
+const (
+	cachePrefix = "id-token"
+	tokenTTL    = 1 * time.Hour
+	cacheTTL    = 58 * time.Minute
+)
+
+var _ auth.IDService = (*Service)(nil)
+
+func ProvideService(cfg *setting.Cfg, signer auth.IDSigner, cache remotecache.CacheStorage) *Service {
+	return &Service{cfg, log.New("id-service"), signer, cache}
+}
+
+type Service struct {
+	cfg    *setting.Cfg
+	logger log.Logger
+	signer auth.IDSigner
+	cache  remotecache.CacheStorage
+}
+
+func (s *Service) SignIdentity(ctx context.Context, id identity.Requester) (string, error) {
+	namespace, identifier := id.GetNamespacedID()
+
+	cacheKey := prefixCacheKey(id.GetCacheKey())
+	cachedToken, err := s.cache.Get(ctx, cacheKey)
+	if err == nil {
+		s.logger.Debug("Cached token found", "namespace", namespace, "id", identifier)
+		return string(cachedToken), nil
+	}
+
+	s.logger.Debug("Sign new id token", "namespace", namespace, "id", identifier)
+
+	now := time.Now()
+
+	token, err := s.signer.SignIDToken(ctx, &auth.IDClaims{
+		Claims: jwt.Claims{
+			ID:       identifier,
+			Issuer:   s.cfg.AppURL,
+			Audience: jwt.Audience{strconv.FormatInt(id.GetOrgID(), 10)},
+			Subject:  fmt.Sprintf("%s:%s", namespace, identifier),
+			Expiry:   jwt.NewNumericDate(now.Add(tokenTTL)),
+			IssuedAt: jwt.NewNumericDate(now),
+		},
+	})
+
+	if err != nil {
+		return "", err
+	}
+
+	if err := s.cache.Set(ctx, cacheKey, []byte(token), cacheTTL); err != nil {
+		s.logger.Error("failed to set cache", "error", err)
+	}
+
+	return token, nil
+}
+
+func prefixCacheKey(key string) string {
+	return fmt.Sprintf("%s-%s", cachePrefix, key)
+}

pkg/services/auth/idimpl/signer.go

@@ -0,0 +1,45 @@
+package idimpl
+
+import (
+	"context"
+
+	"github.com/go-jose/go-jose/v3"
+	"github.com/go-jose/go-jose/v3/jwt"
+
+	"github.com/grafana/grafana/pkg/services/auth"
+	"github.com/grafana/grafana/pkg/services/signingkeys"
+)
+
+var _ auth.IDSigner = (*LocalSigner)(nil)
+
+func ProvideLocalSigner(keyService signingkeys.Service) (*LocalSigner, error) {
+	key := keyService.GetServerPrivateKey() // FIXME: replace with signing specific key
+
+	signer, err := jose.NewSigner(jose.SigningKey{Algorithm: jose.ES256, Key: key}, &jose.SignerOptions{
+		ExtraHeaders: map[jose.HeaderKey]interface{}{
+			"kid": "default", // FIXME: replace with specific key id
+		},
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return &LocalSigner{
+		signer: signer,
+	}, nil
+}
+
+type LocalSigner struct {
+	signer jose.Signer
+}
+
+func (s *LocalSigner) SignIDToken(ctx context.Context, claims *auth.IDClaims) (string, error) {
+	builder := jwt.Signed(s.signer).Claims(claims.Claims)
+
+	token, err := builder.CompactSerialize()
+	if err != nil {
+		return "", err
+	}
+
+	return token, nil
+}