Add impersonated user to system:authenticated group

Currently if a group is specified for an impersonated user,
'system:authenticated' is not added to the 'Groups' list inside the
request context.
This causes priority and fairness match to fail. The catch-all flow
schema needs the user to be in the 'system:authenticated' or in the
'system:unauthenticated' group. An impersonated user with a specified
group is in neither.

As a general rule, if an impersonated user has passed authorization
checks, we should consider him authenticated.

Kubernetes-commit: 01619cfaf6d2b1bcd96c65239e40add5c046f1e4

pkg/endpoints/filters/impersonation.go

@@ -117,10 +117,37 @@ func WithImpersonation(handler http.Handler, a authorizer.Authorizer, s runtime.
 			}
 		}
 
-		if !groupsSpecified && username != user.Anonymous {
-			// When impersonating a non-anonymous user, if no groups were specified
-			// include the system:authenticated group in the impersonated user info
-			groups = append(groups, user.AllAuthenticated)
+		if username != user.Anonymous {
+			// When impersonating a non-anonymous user, include the 'system:authenticated' group
+			// in the impersonated user info:
+			// - if no groups were specified
+			// - if a group has been specified other than 'system:authenticated'
+			//
+			// If 'system:unauthenticated' group has been specified we should not include
+			// the 'system:authenticated' group.
+			addAuthenticated := true
+			for _, group := range groups {
+				if group == user.AllAuthenticated || group == user.AllUnauthenticated {
+					addAuthenticated = false
+					break
+				}
+			}
+
+			if addAuthenticated {
+				groups = append(groups, user.AllAuthenticated)
+			}
+		} else {
+			addUnauthenticated := true
+			for _, group := range groups {
+				if group == user.AllUnauthenticated {
+					addUnauthenticated = false
+					break
+				}
+			}
+
+			if addUnauthenticated {
+				groups = append(groups, user.AllUnauthenticated)
+			}
 		}
 
 		newUser := &user.DefaultInfo{

pkg/endpoints/filters/impersonation_test.go

@@ -163,7 +163,7 @@ func TestImpersonationFilter(t *testing.T) {
 			impersonationGroups: []string{"some-group"},
 			expectedUser: &user.DefaultInfo{
 				Name:   "system:admin",
-				Groups: []string{"some-group"},
+				Groups: []string{"some-group", "system:authenticated"},
 				Extra:  map[string][]string{},
 			},
 			expectedCode: http.StatusOK,
@@ -308,7 +308,7 @@ func TestImpersonationFilter(t *testing.T) {
 			impersonationUser: "system:anonymous",
 			expectedUser: &user.DefaultInfo{
 				Name:   "system:anonymous",
-				Groups: []string{},
+				Groups: []string{"system:unauthenticated"},
 				Extra:  map[string][]string{},
 			},
 			expectedCode: http.StatusOK,
@@ -341,6 +341,48 @@ func TestImpersonationFilter(t *testing.T) {
 			},
 			expectedCode: http.StatusOK,
 		},
+		{
+			name: "specified-authenticated-group-prevents-double-adding-authenticated-group",
+			user: &user.DefaultInfo{
+				Name:   "dev",
+				Groups: []string{"wheel", "group-impersonater"},
+			},
+			impersonationUser:   "system:admin",
+			impersonationGroups: []string{"some-group", "system:authenticated"},
+			expectedUser: &user.DefaultInfo{
+				Name:   "system:admin",
+				Groups: []string{"some-group", "system:authenticated"},
+				Extra:  map[string][]string{},
+			},
+			expectedCode: http.StatusOK,
+		},
+		{
+			name: "anonymous-user-should-include-unauthenticated-group",
+			user: &user.DefaultInfo{
+				Name: "system:admin",
+			},
+			impersonationUser: "system:anonymous",
+			expectedUser: &user.DefaultInfo{
+				Name:   "system:anonymous",
+				Groups: []string{"system:unauthenticated"},
+				Extra:  map[string][]string{},
+			},
+			expectedCode: http.StatusOK,
+		},
+		{
+			name: "anonymous-user-prevents-double-adding-unauthenticated-group",
+			user: &user.DefaultInfo{
+				Name: "system:admin",
+			},
+			impersonationUser:   "system:anonymous",
+			impersonationGroups: []string{"system:unauthenticated"},
+			expectedUser: &user.DefaultInfo{
+				Name:   "system:anonymous",
+				Groups: []string{"system:unauthenticated"},
+				Extra:  map[string][]string{},
+			},
+			expectedCode: http.StatusOK,
+		},
 	}
 
 	var ctx context.Context
@@ -398,42 +440,44 @@ func TestImpersonationFilter(t *testing.T) {
 	defer server.Close()
 
 	for _, tc := range testCases {
-		func() {
-			lock.Lock()
-			defer lock.Unlock()
-			ctx = request.WithUser(request.NewContext(), tc.user)
-		}()
+		t.Run(tc.name, func(t *testing.T) {
+			func() {
+				lock.Lock()
+				defer lock.Unlock()
+				ctx = request.WithUser(request.NewContext(), tc.user)
+			}()
 
-		req, err := http.NewRequest("GET", server.URL, nil)
-		if err != nil {
-			t.Errorf("%s: unexpected error: %v", tc.name, err)
-			continue
-		}
-		if len(tc.impersonationUser) > 0 {
-			req.Header.Add(authenticationapi.ImpersonateUserHeader, tc.impersonationUser)
-		}
-		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)
+			req, err := http.NewRequest("GET", server.URL, nil)
+			if err != nil {
+				t.Errorf("%s: unexpected error: %v", tc.name, err)
+				return
+			}
+			if len(tc.impersonationUser) > 0 {
+				req.Header.Add(authenticationapi.ImpersonateUserHeader, tc.impersonationUser)
+			}
+			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)
-			continue
-		}
-		if resp.StatusCode != tc.expectedCode {
-			t.Errorf("%s: expected %v, actual %v", tc.name, tc.expectedCode, resp.StatusCode)
-			continue
-		}
+			resp, err := http.DefaultClient.Do(req)
+			if err != nil {
+				t.Errorf("%s: unexpected error: %v", tc.name, err)
+				return
+			}
+			if resp.StatusCode != tc.expectedCode {
+				t.Errorf("%s: expected %v, actual %v", tc.name, tc.expectedCode, resp.StatusCode)
+				return
+			}
 
-		if !reflect.DeepEqual(actualUser, tc.expectedUser) {
-			t.Errorf("%s: expected %#v, actual %#v", tc.name, tc.expectedUser, actualUser)
-			continue
-		}
+			if !reflect.DeepEqual(actualUser, tc.expectedUser) {
+				t.Errorf("%s: expected %#v, actual %#v", tc.name, tc.expectedUser, actualUser)
+				return
+			}
+		})
 	}
 }