allow impersonating user.Info.Extra

pkg/apis/authentication/types.go

@@ -28,6 +28,12 @@ const (
 	// ImpersonateGroupHeader is used to impersonate a particular group during an API server request.
 	// It can be repeated multipled times for multiple groups.
 	ImpersonateGroupHeader = "Impersonate-Group"
+
+	// ImpersonateUserExtraHeaderPrefix is a prefix for any header used to impersonate an entry in the
+	// extra map[string][]string for user.Info.  The key will be every after the prefix.
+	// It can be repeated multipled times for multiple map keys and the same key can be repeated multiple
+	// times to have multiple elements in the slice under a single key
+	ImpersonateUserExtraHeaderPrefix = "Impersonate-Extra-"
 )
 
 // +genclient=true

pkg/apiserver/handler_impersonation.go

@@ -17,7 +17,9 @@ limitations under the License.
 package apiserver
 
 import (
+	"fmt"
 	"net/http"
+	"strings"
 
 	"github.com/golang/glog"
 
@@ -32,20 +34,17 @@ import (
 // WithImpersonation is a filter that will inspect and check requests that attempt to change the user.Info for their requests
 func WithImpersonation(handler http.Handler, requestContextMapper api.RequestContextMapper, a authorizer.Authorizer) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
-		requestedUser := req.Header.Get(authenticationapi.ImpersonateUserHeader)
-		if len(requestedUser) == 0 {
-			if len(req.Header[authenticationapi.ImpersonateGroupHeader]) > 0 {
-				glog.V(4).Infof("attempt to impersonate groups without impersonating a user: %v", req.Header[authenticationapi.ImpersonateGroupHeader])
-				forbidden(w, req)
-				return
-			}
-
+		impersonationRequests, err := buildImpersonationRequests(req.Header)
+		if err != nil {
+			glog.V(4).Infof("%v", err)
+			forbidden(w, req)
+			return
+		}
+		if len(impersonationRequests) == 0 {
 			handler.ServeHTTP(w, req)
 			return
 		}
 
-		impersonationRequests := buildImpersonationRequests(requestedUser, req.Header[authenticationapi.ImpersonateGroupHeader])
-
 		ctx, exists := requestContextMapper.Get(req)
 		if !exists {
 			forbidden(w, req)
@@ -65,6 +64,7 @@ func WithImpersonation(handler http.Handler, requestContextMapper api.RequestCon
 		// and group information
 		username := ""
 		groups := []string{}
+		userExtra := map[string][]string{}
 		for _, impersonationRequest := range impersonationRequests {
 			actingAsAttributes := &authorizer.AttributesRecord{
 				User:            requestor,
@@ -92,8 +92,15 @@ func WithImpersonation(handler http.Handler, requestContextMapper api.RequestCon
 				actingAsAttributes.Resource = "groups"
 				groups = append(groups, impersonationRequest.Name)
 
+			case authenticationapi.Kind("UserExtra"):
+				extraKey := impersonationRequest.FieldPath
+				extraValue := impersonationRequest.Name
+				actingAsAttributes.Resource = "userextras"
+				actingAsAttributes.Subresource = extraKey
+				userExtra[extraKey] = append(userExtra[extraKey], extraValue)
+
 			default:
-				glog.V(4).Infof("unknown impersonation request type: %v", impersonationRequest)
+				glog.V(4).Infof("unknown impersonation request type: %v\n", impersonationRequest)
 				forbidden(w, req)
 				return
 			}
@@ -109,7 +116,7 @@ func WithImpersonation(handler http.Handler, requestContextMapper api.RequestCon
 		newUser := &user.DefaultInfo{
 			Name:   username,
 			Groups: groups,
-			Extra:  map[string][]string{},
+			Extra:  userExtra,
 		}
 		requestContextMapper.Update(req, api.WithUser(ctx, newUser))
 
@@ -121,19 +128,55 @@ func WithImpersonation(handler http.Handler, requestContextMapper api.RequestCon
 }
 
 // buildImpersonationRequests returns a list of objectreferences that represent the different things we're requesting to impersonate.
-// Each request must be authorized against the current user before switching contexts
-func buildImpersonationRequests(requestedUser string, requestedGroups []string) []api.ObjectReference {
+// Also includes a map[string][]string representing user.Info.Extra
+// Each request must be authorized against the current user before switching contexts.
+func buildImpersonationRequests(headers http.Header) ([]api.ObjectReference, error) {
 	impersonationRequests := []api.ObjectReference{}
 
-	if namespace, name, err := serviceaccount.SplitUsername(requestedUser); err == nil {
-		impersonationRequests = append(impersonationRequests, api.ObjectReference{Kind: "ServiceAccount", Namespace: namespace, Name: name})
-	} else {
-		impersonationRequests = append(impersonationRequests, api.ObjectReference{Kind: "User", Name: requestedUser})
+	requestedUser := headers.Get(authenticationapi.ImpersonateUserHeader)
+	hasUser := len(requestedUser) > 0
+	if hasUser {
+		if namespace, name, err := serviceaccount.SplitUsername(requestedUser); err == nil {
+			impersonationRequests = append(impersonationRequests, api.ObjectReference{Kind: "ServiceAccount", Namespace: namespace, Name: name})
+		} else {
+			impersonationRequests = append(impersonationRequests, api.ObjectReference{Kind: "User", Name: requestedUser})
+		}
 	}
 
-	for _, group := range requestedGroups {
+	hasGroups := false
+	for _, group := range headers[authenticationapi.ImpersonateGroupHeader] {
+		hasGroups = true
 		impersonationRequests = append(impersonationRequests, api.ObjectReference{Kind: "Group", Name: group})
 	}
 
-	return impersonationRequests
+	hasUserExtra := false
+	for headerName, values := range headers {
+		if !strings.HasPrefix(headerName, authenticationapi.ImpersonateUserExtraHeaderPrefix) {
+			continue
+		}
+
+		hasUserExtra = true
+		extraKey := strings.ToLower(headerName[len(authenticationapi.ImpersonateUserExtraHeaderPrefix):])
+
+		// make a separate request for each extra value they're trying to set
+		for _, value := range values {
+			impersonationRequests = append(impersonationRequests,
+				api.ObjectReference{
+					Kind: "UserExtra",
+					// we only parse out a group above, but the parsing will fail if there isn't SOME version
+					// using the internal version will help us fail if anyone starts using it
+					APIVersion: authenticationapi.SchemeGroupVersion.String(),
+					Name:       value,
+					// ObjectReference doesn't have a subresource field.  FieldPath is close and available, so we'll use that
+					// TODO fight the good fight for ObjectReference to refer to resources and subresources
+					FieldPath: extraKey,
+				})
+		}
+	}
+
+	if (hasGroups || hasUserExtra) && !hasUser {
+		return nil, fmt.Errorf("requested %v without impersonating a user", impersonationRequests)
+	}
+
+	return impersonationRequests, nil
 }

pkg/apiserver/handler_impersonation_test.go

@@ -62,17 +62,31 @@ func (impersonateAuthorizer) Authorize(a authorizer.Attributes) (authorized bool
 		return true, "", nil
 	}
 
+	if len(user.GetGroups()) > 1 && user.GetGroups()[1] == "extra-setter-scopes" && a.GetVerb() == "impersonate" && a.GetResource() == "userextras" && a.GetSubresource() == "scopes" {
+		return true, "", nil
+	}
+
+	if len(user.GetGroups()) > 1 && user.GetGroups()[1] == "extra-setter-particular-scopes" &&
+		a.GetVerb() == "impersonate" && a.GetResource() == "userextras" && a.GetSubresource() == "scopes" && a.GetName() == "scope-a" {
+		return true, "", nil
+	}
+
+	if len(user.GetGroups()) > 1 && user.GetGroups()[1] == "extra-setter-project" && a.GetVerb() == "impersonate" && a.GetResource() == "userextras" && a.GetSubresource() == "project" {
+		return true, "", nil
+	}
+
 	return false, "deny by default", nil
 }
 
 func TestImpersonationFilter(t *testing.T) {
 	testCases := []struct {
-		name                string
-		user                user.Info
-		impersonationUser   string
-		impersonationGroups []string
-		expectedUser        user.Info
-		expectedCode        int
+		name                    string
+		user                    user.Info
+		impersonationUser       string
+		impersonationGroups     []string
+		impersonationUserExtras map[string][]string
+		expectedUser            user.Info
+		expectedCode            int
 	}{
 		{
 			name: "not-impersonating",
@@ -106,6 +120,17 @@ func TestImpersonationFilter(t *testing.T) {
 			},
 			expectedCode: http.StatusForbidden,
 		},
+		{
+			name: "impersonating-extra-without-user",
+			user: &user.DefaultInfo{
+				Name: "tester",
+			},
+			impersonationUserExtras: map[string][]string{"scopes": {"scope-a"}},
+			expectedUser: &user.DefaultInfo{
+				Name: "tester",
+			},
+			expectedCode: http.StatusForbidden,
+		},
 		{
 			name: "disallowed-group",
 			user: &user.DefaultInfo{
@@ -135,6 +160,66 @@ func TestImpersonationFilter(t *testing.T) {
 			},
 			expectedCode: http.StatusOK,
 		},
+		{
+			name: "disallowed-userextra-1",
+			user: &user.DefaultInfo{
+				Name:   "dev",
+				Groups: []string{"wheel"},
+			},
+			impersonationUser:       "system:admin",
+			impersonationGroups:     []string{"some-group"},
+			impersonationUserExtras: map[string][]string{"scopes": {"scope-a"}},
+			expectedUser: &user.DefaultInfo{
+				Name:   "dev",
+				Groups: []string{"wheel"},
+			},
+			expectedCode: http.StatusForbidden,
+		},
+		{
+			name: "disallowed-userextra-2",
+			user: &user.DefaultInfo{
+				Name:   "dev",
+				Groups: []string{"wheel", "extra-setter-project"},
+			},
+			impersonationUser:       "system:admin",
+			impersonationGroups:     []string{"some-group"},
+			impersonationUserExtras: map[string][]string{"scopes": {"scope-a"}},
+			expectedUser: &user.DefaultInfo{
+				Name:   "dev",
+				Groups: []string{"wheel", "extra-setter-project"},
+			},
+			expectedCode: http.StatusForbidden,
+		},
+		{
+			name: "disallowed-userextra-3",
+			user: &user.DefaultInfo{
+				Name:   "dev",
+				Groups: []string{"wheel", "extra-setter-particular-scopes"},
+			},
+			impersonationUser:       "system:admin",
+			impersonationGroups:     []string{"some-group"},
+			impersonationUserExtras: map[string][]string{"scopes": {"scope-a", "scope-b"}},
+			expectedUser: &user.DefaultInfo{
+				Name:   "dev",
+				Groups: []string{"wheel", "extra-setter-particular-scopes"},
+			},
+			expectedCode: http.StatusForbidden,
+		},
+		{
+			name: "allowed-userextras",
+			user: &user.DefaultInfo{
+				Name:   "dev",
+				Groups: []string{"wheel", "extra-setter-scopes"},
+			},
+			impersonationUser:       "system:admin",
+			impersonationUserExtras: map[string][]string{"scopes": {"scope-a", "scope-b"}},
+			expectedUser: &user.DefaultInfo{
+				Name:   "system:admin",
+				Groups: []string{},
+				Extra:  map[string][]string{"scopes": {"scope-a", "scope-b"}},
+			},
+			expectedCode: http.StatusOK,
+		},
 		{
 			name: "allowed-users-impersonation",
 			user: &user.DefaultInfo{
@@ -238,6 +323,12 @@ func TestImpersonationFilter(t *testing.T) {
 		for _, group := range tc.impersonationGroups {
 			req.Header.Add(authenticationapi.ImpersonateGroupHeader, group)
 		}
+		for extraKey, values := range tc.impersonationUserExtras {
+			for _, value := range values {
+				req.Header.Add(authenticationapi.ImpersonateUserExtraHeaderPrefix+extraKey, value)
+			}
+		}
+
 		resp, err := http.DefaultClient.Do(req)
 		if err != nil {
 			t.Errorf("%s: unexpected error: %v", tc.name, err)

pkg/auth/user/user.go

@@ -36,6 +36,8 @@ type Info interface {
 	// This is a map[string][]string because it needs to be serializeable into
 	// a SubjectAccessReviewSpec.authorization.k8s.io for proper authorization
 	// delegation flows
+	// In order to faithfully round-trip through an impersonation flow, these keys
+	// MUST be lowercase.
 	GetExtra() map[string][]string
 }