fix: Limit access to files based on regex pattern (#23413)

packages/@n8n/config/src/configs/security.config.ts

@@ -20,6 +20,14 @@ export class SecurityConfig {
 	@Env('N8N_BLOCK_FILE_ACCESS_TO_N8N_FILES')
 	blockFileAccessToN8nFiles: boolean = true;
 
+	/**
+	 * Blocked file and folder regular expression patterns that `ReadWriteFile` and `ReadBinaryFiles` nodes cant access. Separate multiple patterns with with semicolon `;`.
+	 * - `^(.*\/)*\.git(\/.*)*$`
+	 * Set to empty to not block based on file patterns.
+	 */
+	@Env('N8N_BLOCK_FILE_PATTERNS')
+	blockFilePatterns: string = '^(.*\\/)*\\.git(\\/.*)*$';
+
 	/**
 	 * In a [security audit](https://docs.n8n.io/hosting/securing/security-audit/), how many days for a workflow to be considered abandoned if not executed.
 	 */

packages/@n8n/config/test/config.test.ts

@@ -322,6 +322,7 @@ describe('GlobalConfig', () => {
 		security: {
 			restrictFileAccessTo: '~/.n8n-files',
 			blockFileAccessToN8nFiles: true,
+			blockFilePatterns: '^(.*\\/)*\\.git(\\/.*)*$',
 			daysAbandonedWorkflow: 90,
 			contentSecurityPolicy: '{}',
 			contentSecurityPolicyReportOnly: false,

packages/core/src/execution-engine/node-execution-context/utils/__tests__/file-system-helper-functions.test.ts

@@ -24,6 +24,8 @@ const originalProcessEnv = { ...process.env };
 
 let instanceSettings: InstanceSettings;
 let securityConfig: SecurityConfig;
+let originalBlockedFilePatterns: string;
+
 beforeEach(() => {
 	process.env = { ...originalProcessEnv };
 
@@ -36,6 +38,11 @@ beforeEach(() => {
 	instanceSettings = Container.get(InstanceSettings);
 	securityConfig = Container.get(SecurityConfig);
 	securityConfig.restrictFileAccessTo = '';
+	originalBlockedFilePatterns = securityConfig.blockFilePatterns;
+});
+
+afterEach(() => {
+	securityConfig.blockFilePatterns = originalBlockedFilePatterns;
 });
 
 describe('isFilePathBlocked', () => {
@@ -185,6 +192,45 @@ describe('isFilePathBlocked', () => {
 		(fsRealpath as jest.Mock).mockRejectedValueOnce(error);
 		expect(isFilePathBlocked(await resolvePath(filePath))).toBe(true);
 	});
+
+	it.each(['.git', '/.git', '/tmp/.git', '/tmp/.git/config'])(
+		'should per default block access to %s',
+		async (path) => {
+			expect(isFilePathBlocked(await resolvePath(path))).toBe(true);
+		},
+	);
+
+	it('should allow access when pattern matching is disabled', async () => {
+		securityConfig.blockFilePatterns = '';
+		expect(isFilePathBlocked(await resolvePath('/tmp/.git'))).toBe(false);
+	});
+
+	it('should block all access when using invalid pattern', async () => {
+		securityConfig.blockFilePatterns = '(';
+		expect(isFilePathBlocked(await resolvePath('/tmp/xo'))).toBe(true);
+	});
+
+	describe('when multiple file patterns are configured', () => {
+		beforeEach(() => {
+			securityConfig.blockFilePatterns = 'hello; \\/there$; ^where';
+		});
+
+		it.each([
+			'hello',
+			'xhellox',
+			'subpath/hello/',
+			'/there',
+			'/subpath/there',
+			'where',
+			'where-is/it',
+		])('should block access to %s', async (path) => {
+			expect(isFilePathBlocked(await resolvePath(path))).toBe(true);
+		});
+
+		it.each(['/there/is', '/where'])('should not block access to %s', async (path) => {
+			expect(isFilePathBlocked(await resolvePath(path))).toBe(false);
+		});
+	});
 });
 
 describe('getFileSystemHelperFunctions', () => {

packages/core/src/execution-engine/node-execution-context/utils/file-system-helper-functions.ts

@@ -47,6 +47,22 @@ async function resolvePath(path: PathLike): Promise<ResolvedFilePath> {
 	}
 }
 
+function isFilePatternBlocked(resolvedFilePath: ResolvedFilePath): boolean {
+	const { blockFilePatterns } = Container.get(SecurityConfig);
+
+	return blockFilePatterns
+		.split(';')
+		.map((pattern) => pattern.trim())
+		.filter((pattern) => pattern)
+		.some((pattern) => {
+			try {
+				return new RegExp(pattern, 'mi').test(resolvedFilePath);
+			} catch {
+				return true;
+			}
+		});
+}
+
 function isFilePathBlocked(resolvedFilePath: ResolvedFilePath): boolean {
 	const allowedPaths = getAllowedPaths();
 	const blockFileAccessToN8nFiles = process.env[BLOCK_FILE_ACCESS_TO_N8N_FILES] !== 'false';
@@ -58,6 +74,10 @@ function isFilePathBlocked(resolvedFilePath: ResolvedFilePath): boolean {
 		return true;
 	}
 
+	if (isFilePatternBlocked(resolvedFilePath)) {
+		return true;
+	}
+
 	if (allowedPaths.length) {
 		return !allowedPaths.some((allowedPath) => isContainedWithin(allowedPath, resolvedFilePath));
 	}