Add allowedExtensions setting (#17695)

docs/cli/settings.md

@@ -107,13 +107,14 @@ they appear in the UI.
 
 ### Security
 
-| UI Label                              | Setting                                         | Description                                                                     | Default |
+| UI Label                              | Setting                                         | Description                                                                                                                                                             | Default |
-| ------------------------------------- | ----------------------------------------------- | ------------------------------------------------------------------------------- | ------- |
+| ------------------------------------- | ----------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------- |
-| Disable YOLO Mode                     | `security.disableYoloMode`                      | Disable YOLO mode, even if enabled by a flag.                                   | `false` |
+| Disable YOLO Mode                     | `security.disableYoloMode`                      | Disable YOLO mode, even if enabled by a flag.                                                                                                                           | `false` |
-| Allow Permanent Tool Approval         | `security.enablePermanentToolApproval`          | Enable the "Allow for all future sessions" option in tool confirmation dialogs. | `false` |
+| Allow Permanent Tool Approval         | `security.enablePermanentToolApproval`          | Enable the "Allow for all future sessions" option in tool confirmation dialogs.                                                                                         | `false` |
-| Blocks extensions from Git            | `security.blockGitExtensions`                   | Blocks installing and loading extensions from Git.                              | `false` |
+| Blocks extensions from Git            | `security.blockGitExtensions`                   | Blocks installing and loading extensions from Git.                                                                                                                      | `false` |
-| Folder Trust                          | `security.folderTrust.enabled`                  | Setting to track whether Folder trust is enabled.                               | `false` |
+| Extension Source Regex Allowlist      | `security.allowedExtensions`                    | List of Regex patterns for allowed extensions. If nonempty, only extensions that match the patterns in this list are allowed. Overrides the blockGitExtensions setting. | `[]`    |
-| Enable Environment Variable Redaction | `security.environmentVariableRedaction.enabled` | Enable redaction of environment variables that may contain secrets.             | `false` |
+| Folder Trust                          | `security.folderTrust.enabled`                  | Setting to track whether Folder trust is enabled.                                                                                                                       | `false` |
+| Enable Environment Variable Redaction | `security.environmentVariableRedaction.enabled` | Enable redaction of environment variables that may contain secrets.                                                                                                     | `false` |
 
 ### Experimental
 

docs/get-started/configuration.md

@@ -773,6 +773,13 @@ their corresponding top-level category object in your `settings.json` file.
   - **Default:** `false`
   - **Requires restart:** Yes
 
+- **`security.allowedExtensions`** (array):
+  - **Description:** List of Regex patterns for allowed extensions. If nonempty,
+    only extensions that match the patterns in this list are allowed. Overrides
+    the blockGitExtensions setting.
+  - **Default:** `[]`
+  - **Requires restart:** Yes
+
 - **`security.folderTrust.enabled`** (boolean):
   - **Description:** Setting to track whether Folder trust is enabled.
   - **Default:** `false`

packages/cli/src/config/extension-manager.ts

@@ -144,6 +144,26 @@ export class ExtensionManager extends ExtensionLoader {
     previousExtensionConfig?: ExtensionConfig,
   ): Promise<GeminiCLIExtension> {
     if (
+      this.settings.security?.allowedExtensions &&
+      this.settings.security?.allowedExtensions.length > 0
+    ) {
+      const extensionAllowed = this.settings.security?.allowedExtensions.some(
+        (pattern) => {
+          try {
+            return new RegExp(pattern).test(installMetadata.source);
+          } catch (e) {
+            throw new Error(
+              `Invalid regex pattern in allowedExtensions setting: "${pattern}. Error: ${getErrorMessage(e)}`,
+            );
+          }
+        },
+      );
+      if (!extensionAllowed) {
+        throw new Error(
+          `Installing extension from source "${installMetadata.source}" is not allowed by the "allowedExtensions" security setting.`,
+        );
+      }
+    } else if (
       (installMetadata.type === 'git' ||
         installMetadata.type === 'github-release') &&
       this.settings.security.blockGitExtensions
@@ -152,6 +172,7 @@ export class ExtensionManager extends ExtensionLoader {
         'Installing extensions from remote sources is disallowed by your current settings.',
       );
     }
+
     const isUpdate = !!previousExtensionConfig;
     let newExtensionConfig: ExtensionConfig | null = null;
     let localSourcePath: string | undefined;
@@ -522,10 +543,39 @@ Would you like to attempt to install via "git clone" instead?`,
     const installMetadata = loadInstallMetadata(extensionDir);
     let effectiveExtensionPath = extensionDir;
     if (
+      this.settings.security?.allowedExtensions &&
+      this.settings.security?.allowedExtensions.length > 0
+    ) {
+      if (!installMetadata?.source) {
+        throw new Error(
+          `Failed to load extension ${extensionDir}. The ${INSTALL_METADATA_FILENAME} file is missing or misconfigured.`,
+        );
+      }
+      const extensionAllowed = this.settings.security?.allowedExtensions.some(
+        (pattern) => {
+          try {
+            return new RegExp(pattern).test(installMetadata?.source);
+          } catch (e) {
+            throw new Error(
+              `Invalid regex pattern in allowedExtensions setting: "${pattern}. Error: ${getErrorMessage(e)}`,
+            );
+          }
+        },
+      );
+      if (!extensionAllowed) {
+        debugLogger.warn(
+          `Failed to load extension ${extensionDir}. This extension is not allowed by the "allowedExtensions" security setting.`,
+        );
+        return null;
+      }
+    } else if (
       (installMetadata?.type === 'git' ||
         installMetadata?.type === 'github-release') &&
       this.settings.security.blockGitExtensions
     ) {
+      debugLogger.warn(
+        `Failed to load extension ${extensionDir}. Extensions from remote sources is disallowed by your current settings.`,
+      );
       return null;
     }
 

packages/cli/src/config/extension.test.ts

@@ -622,6 +622,7 @@ describe('extension tests', () => {
     });
 
     it('should not load github extensions if blockGitExtensions is set', async () => {
+      const consoleSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
       createExtension({
         extensionsDir: userExtensionsDir,
         name: 'my-ext',
@@ -645,6 +646,73 @@ describe('extension tests', () => {
       const extension = extensions.find((e) => e.name === 'my-ext');
 
       expect(extension).toBeUndefined();
+      expect(consoleSpy).toHaveBeenCalledWith(
+        expect.stringContaining(
+          'Extensions from remote sources is disallowed by your current settings.',
+        ),
+      );
+      consoleSpy.mockRestore();
+    });
+
+    it('should load allowed extensions if the allowlist is set.', async () => {
+      createExtension({
+        extensionsDir: userExtensionsDir,
+        name: 'my-ext',
+        version: '1.0.0',
+        installMetadata: {
+          type: 'git',
+          source: 'http://allowed.com/foo/bar',
+        },
+      });
+      const extensionAllowlistSetting = createTestMergedSettings({
+        security: {
+          allowedExtensions: ['\\b(https?:\\/\\/)?(www\\.)?allowed\\.com\\S*'],
+        },
+      });
+      extensionManager = new ExtensionManager({
+        workspaceDir: tempWorkspaceDir,
+        requestConsent: mockRequestConsent,
+        requestSetting: mockPromptForSettings,
+        settings: extensionAllowlistSetting,
+      });
+      const extensions = await extensionManager.loadExtensions();
+
+      expect(extensions).toHaveLength(1);
+      expect(extensions[0].name).toBe('my-ext');
+    });
+
+    it('should not load disallowed extensions if the allowlist is set.', async () => {
+      const consoleSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
+      createExtension({
+        extensionsDir: userExtensionsDir,
+        name: 'my-ext',
+        version: '1.0.0',
+        installMetadata: {
+          type: 'git',
+          source: 'http://notallowed.com/foo/bar',
+        },
+      });
+      const extensionAllowlistSetting = createTestMergedSettings({
+        security: {
+          allowedExtensions: ['\\b(https?:\\/\\/)?(www\\.)?allowed\\.com\\S*'],
+        },
+      });
+      extensionManager = new ExtensionManager({
+        workspaceDir: tempWorkspaceDir,
+        requestConsent: mockRequestConsent,
+        requestSetting: mockPromptForSettings,
+        settings: extensionAllowlistSetting,
+      });
+      const extensions = await extensionManager.loadExtensions();
+      const extension = extensions.find((e) => e.name === 'my-ext');
+
+      expect(extension).toBeUndefined();
+      expect(consoleSpy).toHaveBeenCalledWith(
+        expect.stringContaining(
+          'This extension is not allowed by the "allowedExtensions" security setting',
+        ),
+      );
+      consoleSpy.mockRestore();
     });
 
     it('should not load any extensions if admin.extensions.enabled is false', async () => {
@@ -1116,6 +1184,30 @@ describe('extension tests', () => {
       );
     });
 
+    it('should not install a disallowed extension if the allowlist is set', async () => {
+      const gitUrl = 'https://somehost.com/somerepo.git';
+      const allowedExtensionsSetting = createTestMergedSettings({
+        security: {
+          allowedExtensions: ['\\b(https?:\\/\\/)?(www\\.)?allowed\\.com\\S*'],
+        },
+      });
+      extensionManager = new ExtensionManager({
+        workspaceDir: tempWorkspaceDir,
+        requestConsent: mockRequestConsent,
+        requestSetting: mockPromptForSettings,
+        settings: allowedExtensionsSetting,
+      });
+      await extensionManager.loadExtensions();
+      await expect(
+        extensionManager.installOrUpdateExtension({
+          source: gitUrl,
+          type: 'git',
+        }),
+      ).rejects.toThrow(
+        `Installing extension from source "${gitUrl}" is not allowed by the "allowedExtensions" security setting.`,
+      );
+    });
+
     it('should prompt for trust if workspace is not trusted', async () => {
       vi.mocked(isWorkspaceTrusted).mockReturnValue({
         isTrusted: false,

packages/cli/src/config/settingsSchema.ts

@@ -1268,6 +1268,17 @@ const SETTINGS_SCHEMA = {
         description: 'Blocks installing and loading extensions from Git.',
         showInDialog: true,
       },
+      allowedExtensions: {
+        type: 'array',
+        label: 'Extension Source Regex Allowlist',
+        category: 'Security',
+        requiresRestart: true,
+        default: [] as string[],
+        description:
+          'List of Regex patterns for allowed extensions. If nonempty, only extensions that match the patterns in this list are allowed. Overrides the blockGitExtensions setting.',
+        showInDialog: true,
+        items: { type: 'string' },
+      },
       folderTrust: {
         type: 'object',
         label: 'Folder Trust',

schemas/settings.schema.json

@@ -1273,6 +1273,16 @@
           "default": false,
           "type": "boolean"
         },
+        "allowedExtensions": {
+          "title": "Extension Source Regex Allowlist",
+          "description": "List of Regex patterns for allowed extensions. If nonempty, only extensions that match the patterns in this list are allowed. Overrides the blockGitExtensions setting.",
+          "markdownDescription": "List of Regex patterns for allowed extensions. If nonempty, only extensions that match the patterns in this list are allowed. Overrides the blockGitExtensions setting.\n\n- Category: `Security`\n- Requires restart: `yes`\n- Default: `[]`",
+          "default": [],
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        },
         "folderTrust": {
           "title": "Folder Trust",
           "description": "Settings for folder trust.",