Explicitly require that delegate API keys have no privileges

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/security/authz/RoleDescriptor.java

@@ -212,6 +212,16 @@ public int hashCode() {
         return result;
     }
 
+
+    public boolean isEmpty() {
+        return clusterPrivileges.length == 0
+            && configurableClusterPrivileges.length == 0
+            && indicesPrivileges.length == 0
+            && applicationPrivileges.length == 0
+            && runAs.length == 0
+            && metadata.size() == 0;
+    }
+
     @Override
     public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
         return toXContent(builder, params, false);

x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/action/TransportCreateApiKeyAction.java

@@ -18,6 +18,7 @@
 import org.elasticsearch.xpack.core.security.action.CreateApiKeyRequest;
 import org.elasticsearch.xpack.core.security.action.CreateApiKeyResponse;
 import org.elasticsearch.xpack.core.security.authc.Authentication;
+import org.elasticsearch.xpack.core.security.authz.RoleDescriptor;
 import org.elasticsearch.xpack.security.authc.ApiKeyService;
 import org.elasticsearch.xpack.security.authc.support.ApiKeyGenerator;
 import org.elasticsearch.xpack.security.authz.store.CompositeRolesStore;
@@ -44,7 +45,18 @@ protected void doExecute(Task task, CreateApiKeyRequest request, ActionListener<
         if (authentication == null) {
             listener.onFailure(new IllegalStateException("authentication is required"));
         } else {
+            if (Authentication.AuthenticationType.API_KEY == authentication.getAuthenticationType() && grantsAnyPrivileges(request)) {
+                listener.onFailure(new IllegalArgumentException(
+                    "creating derived api keys requires an explicit role descriptor that is empty (has no privileges)"));
+                return;
+            }
             generator.generateApiKey(authentication, request, listener);
         }
     }
+
+    private boolean grantsAnyPrivileges(CreateApiKeyRequest request) {
+        return request.getRoleDescriptors() == null
+            || request.getRoleDescriptors().isEmpty()
+            || false == request.getRoleDescriptors().stream().allMatch(RoleDescriptor::isEmpty);
+    }
 }

x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authc/ApiKeyIntegTests.java

@@ -9,6 +9,8 @@
 import com.google.common.collect.Sets;
 import org.elasticsearch.ElasticsearchSecurityException;
 import org.elasticsearch.action.DocWriteResponse;
+import org.elasticsearch.action.admin.indices.refresh.RefreshAction;
+import org.elasticsearch.action.admin.indices.refresh.RefreshRequestBuilder;
 import org.elasticsearch.action.admin.indices.refresh.RefreshResponse;
 import org.elasticsearch.action.support.PlainActionFuture;
 import org.elasticsearch.action.support.WriteRequest;
@@ -758,6 +760,75 @@ public void testApiKeyWithManageOwnPrivilegeIsAbleToInvalidateItselfButNotAnyOth
         assertThat(invalidateResponse.getErrors().size(), equalTo(0));
     }
 
+    public void testDerivedKeys() throws ExecutionException, InterruptedException {
+        Client client = client().filterWithHeader(Collections.singletonMap("Authorization",
+            UsernamePasswordToken.basicAuthHeaderValue(SecuritySettingsSource.TEST_SUPERUSER,
+                SecuritySettingsSourceField.TEST_PASSWORD_SECURE_STRING)));
+        final CreateApiKeyResponse response = new CreateApiKeyRequestBuilder(client)
+            .setName("key-1")
+            .setRoleDescriptors(Collections.singletonList(
+                new RoleDescriptor("role", new String[] { "manage_api_key" }, null, null)))
+            .get();
+
+        assertEquals("key-1", response.getName());
+        assertNotNull(response.getId());
+        assertNotNull(response.getKey());
+
+        // use the first ApiKey for authorized action
+        final String base64ApiKeyKeyValue = Base64.getEncoder().encodeToString(
+            (response.getId() + ":" + response.getKey().toString()).getBytes(StandardCharsets.UTF_8));
+        final Client clientKey1 = client().filterWithHeader(Collections.singletonMap("Authorization", "ApiKey " + base64ApiKeyKeyValue));
+
+        final String expectedMessage = "creating derived api keys requires an explicit role descriptor that is empty";
+
+        final IllegalArgumentException e1 = expectThrows(IllegalArgumentException.class,
+                () -> new CreateApiKeyRequestBuilder(clientKey1).setName("key-2").get());
+        assertThat(e1.getMessage(), containsString(expectedMessage));
+
+        final IllegalArgumentException e2 = expectThrows(IllegalArgumentException.class,
+            () -> new CreateApiKeyRequestBuilder(clientKey1).setName("key-3")
+                .setRoleDescriptors(Collections.emptyList()).get());
+        assertThat(e2.getMessage(), containsString(expectedMessage));
+
+        final IllegalArgumentException e3 = expectThrows(IllegalArgumentException.class,
+            () -> new CreateApiKeyRequestBuilder(clientKey1).setName("key-4")
+                .setRoleDescriptors(Collections.singletonList(
+                    new RoleDescriptor("role", new String[] {"manage_own_api_key"}, null, null)
+                )).get());
+        assertThat(e3.getMessage(), containsString(expectedMessage));
+
+        final List<RoleDescriptor> roleDescriptors = randomList(2, 10,
+            () -> new RoleDescriptor("role", null, null, null));
+        roleDescriptors.set(randomInt(roleDescriptors.size() - 1),
+            new RoleDescriptor("role", new String[] {"manage_own_api_key"}, null, null));
+
+        final IllegalArgumentException e4 = expectThrows(IllegalArgumentException.class,
+            () -> new CreateApiKeyRequestBuilder(clientKey1).setName("key-5")
+                .setRoleDescriptors(roleDescriptors).get());
+        assertThat(e4.getMessage(), containsString(expectedMessage));
+
+        final CreateApiKeyResponse key100Response = new CreateApiKeyRequestBuilder(clientKey1).setName("key-100")
+            .setRoleDescriptors(Collections.singletonList(
+                new RoleDescriptor("role", null, null, null)
+            )).get();
+        assertEquals("key-100", key100Response.getName());
+        assertNotNull(key100Response.getId());
+        assertNotNull(key100Response.getKey());
+
+        // Check at the end to allow sometime for the operation to happen. Since an erroneous creation is
+        // asynchronous so that the document is not available immediately.
+        assertApiKeyNotCreated(client, "key-2");
+        assertApiKeyNotCreated(client, "key-3");
+        assertApiKeyNotCreated(client, "key-4");
+        assertApiKeyNotCreated(client, "key-5");
+    }
+
+    private void assertApiKeyNotCreated(Client client, String keyName) throws ExecutionException, InterruptedException {
+        new RefreshRequestBuilder(client, RefreshAction.INSTANCE).setIndices(SECURITY_MAIN_ALIAS).execute().get();
+        assertEquals(0, client.execute(GetApiKeyAction.INSTANCE,
+            GetApiKeyRequest.usingApiKeyName(keyName, false)).get().getApiKeyInfos().length);
+    }
+
     private void verifyGetResponse(int expectedNumberOfApiKeys, List<CreateApiKeyResponse> responses,
                                    GetApiKeyResponse response, Set<String> validApiKeyIds, List<String> invalidatedApiKeyIds) {
         verifyGetResponse(SecuritySettingsSource.TEST_SUPERUSER, expectedNumberOfApiKeys, responses, response, validApiKeyIds,

x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authz/RoleDescriptorTests.java

@@ -32,7 +32,9 @@
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.LinkedHashSet;
+import java.util.List;
 import java.util.Map;
 
 import static org.elasticsearch.common.xcontent.XContentFactory.jsonBuilder;
@@ -325,4 +327,55 @@ public void testParseIndicesPrivilegesFailsWhenExceptFieldsAreNotSubsetOfGranted
         assertThat(epe, TestMatchers.throwableWithMessage(containsString("f2")));
         assertThat(epe, TestMatchers.throwableWithMessage(containsString("f3")));
     }
+
+    public void testIsEmpty() {
+        assertTrue(new RoleDescriptor(
+            randomAlphaOfLengthBetween(1, 10), null, null, null, null, null, null, null)
+            .isEmpty());
+
+        assertTrue(new RoleDescriptor(
+            randomAlphaOfLengthBetween(1, 10),
+            new String[0],
+            new RoleDescriptor.IndicesPrivileges[0],
+            new RoleDescriptor.ApplicationResourcePrivileges[0],
+            new ConfigurableClusterPrivilege[0],
+            new String[0],
+            new HashMap<>(),
+            new HashMap<>())
+            .isEmpty());
+
+        final List<Boolean> booleans = Arrays.asList(
+            randomBoolean(),
+            randomBoolean(),
+            randomBoolean(),
+            randomBoolean(),
+            randomBoolean(),
+            randomBoolean());
+
+        final RoleDescriptor roleDescriptor = new RoleDescriptor(
+            randomAlphaOfLengthBetween(1, 10),
+            booleans.get(0) ? new String[0] : new String[] { "foo" },
+            booleans.get(1) ?
+                new RoleDescriptor.IndicesPrivileges[0] :
+                new RoleDescriptor.IndicesPrivileges[] {
+                    RoleDescriptor.IndicesPrivileges.builder().indices("idx").privileges("foo").build() },
+            booleans.get(2) ?
+                new RoleDescriptor.ApplicationResourcePrivileges[0] :
+                new RoleDescriptor.ApplicationResourcePrivileges[] {
+                    RoleDescriptor.ApplicationResourcePrivileges.builder()
+                        .application("app").privileges("foo").resources("res").build() },
+            booleans.get(3) ?
+                new ConfigurableClusterPrivilege[0] :
+                new ConfigurableClusterPrivilege[] {
+                    new ConfigurableClusterPrivileges.ManageApplicationPrivileges(Collections.singleton("foo")) },
+            booleans.get(4) ? new String[0] : new String[] { "foo" },
+            booleans.get(5) ? new HashMap<>() : Collections.singletonMap("foo", "bar"),
+            Collections.singletonMap("foo", "bar"));
+
+        if (booleans.stream().anyMatch(e -> e.equals(false))) {
+            assertFalse(roleDescriptor.isEmpty());
+        } else {
+            assertTrue(roleDescriptor.isEmpty());
+        }
+    }
 }