fix(cli): respect sandbox path boundaries (#5375)

packages/cli/src/utils/sandbox-path.ts

@@ -0,0 +1,32 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import path from 'node:path';
+
+export function isContainerPathWithinWorkdir(
+  containerWorkdir: string,
+  containerPath: string,
+): boolean {
+  const normalize = (value: string) => {
+    const normalized = path.posix
+      .normalize(value.replace(/\\/g, '/'))
+      .replace(/\/+$/, '')
+      .toLowerCase();
+    return normalized || '/';
+  };
+
+  const normalizedWorkdir = normalize(containerWorkdir);
+  const normalizedPath = normalize(containerPath);
+
+  if (normalizedWorkdir === '/') {
+    return normalizedPath.startsWith('/');
+  }
+
+  return (
+    normalizedPath === normalizedWorkdir ||
+    normalizedPath.startsWith(`${normalizedWorkdir}/`)
+  );
+}

packages/cli/src/utils/sandbox.test.ts

@@ -5,8 +5,42 @@
  */
 
 import { describe, expect, it } from 'vitest';
+import { isContainerPathWithinWorkdir } from './sandbox-path.js';
 import { parseSandboxImageName } from './sandboxImageName.js';
 
+describe('isContainerPathWithinWorkdir', () => {
+  it('allows the workdir itself', () => {
+    expect(isContainerPathWithinWorkdir('/repo/app', '/repo/app')).toBe(true);
+  });
+
+  it('allows paths under the workdir', () => {
+    expect(isContainerPathWithinWorkdir('/repo/app', '/repo/app/bin')).toBe(
+      true,
+    );
+  });
+
+  it('rejects sibling paths with the same prefix', () => {
+    expect(
+      isContainerPathWithinWorkdir('/repo/app', '/repo/app-tools/bin'),
+    ).toBe(false);
+  });
+
+  it('allows absolute paths under the filesystem root workdir', () => {
+    expect(isContainerPathWithinWorkdir('/', '/bin')).toBe(true);
+  });
+
+  it('normalizes trailing slashes and case for container paths', () => {
+    expect(
+      isContainerPathWithinWorkdir('/C/Repo/App/', '/c/repo/app/bin'),
+    ).toBe(true);
+  });
+
+  it('handles converted Windows drive roots without matching sibling drives', () => {
+    expect(isContainerPathWithinWorkdir('/c', '/c/tools')).toBe(true);
+    expect(isContainerPathWithinWorkdir('/c', '/c2/tools')).toBe(false);
+  });
+});
+
 describe('parseSandboxImageName', () => {
   it('uses the image basename and tag for container names', () => {
     expect(parseSandboxImageName('ghcr.io/qwenlm/qwen-code:0.18.3')).toBe(

packages/cli/src/utils/sandbox.ts

@@ -24,6 +24,7 @@ import {
 import { randomBytes } from 'node:crypto';
 import { writeStderrLine } from './stdioHelpers.js';
 import { parseSandboxImageName } from './sandboxImageName.js';
+import { isContainerPathWithinWorkdir } from './sandbox-path.js';
 
 const execAsync = promisify(exec);
 
@@ -121,9 +122,7 @@ function entrypoint(workdir: string, cliArgs: string[]): string[] {
     const paths = process.env['PATH'].split(pathSeparator);
     for (const p of paths) {
       const containerPath = getContainerPath(p);
-      if (
-        containerPath.toLowerCase().startsWith(containerWorkdir.toLowerCase())
-      ) {
+      if (isContainerPathWithinWorkdir(containerWorkdir, containerPath)) {
         pathSuffix += `:${containerPath}`;
       }
     }
@@ -137,9 +136,7 @@ function entrypoint(workdir: string, cliArgs: string[]): string[] {
     const paths = process.env['PYTHONPATH'].split(pathSeparator);
     for (const p of paths) {
       const containerPath = getContainerPath(p);
-      if (
-        containerPath.toLowerCase().startsWith(containerWorkdir.toLowerCase())
-      ) {
+      if (isContainerPathWithinWorkdir(containerWorkdir, containerPath)) {
         pythonPathSuffix += `:${containerPath}`;
       }
     }
@@ -723,8 +720,13 @@ export async function start_sandbox(
   // also mount-replace VIRTUAL_ENV directory with <project_settings>/sandbox.venv
   // sandbox can then set up this new VIRTUAL_ENV directory using sandbox.bashrc (see below)
   // directory will be empty if not set up, which is still preferable to having host binaries
+  const virtualEnv = process.env['VIRTUAL_ENV'];
   if (
-    process.env['VIRTUAL_ENV']?.toLowerCase().startsWith(workdir.toLowerCase())
+    virtualEnv &&
+    isContainerPathWithinWorkdir(
+      getContainerPath(workdir),
+      getContainerPath(virtualEnv),
+    )
   ) {
     const sandboxVenvPath = path.resolve(
       SETTINGS_DIRECTORY_NAME,
@@ -733,14 +735,8 @@ export async function start_sandbox(
     if (!fs.existsSync(sandboxVenvPath)) {
       fs.mkdirSync(sandboxVenvPath, { recursive: true });
     }
-    args.push(
-      '--volume',
-      `${sandboxVenvPath}:${getContainerPath(process.env['VIRTUAL_ENV'])}`,
-    );
-    args.push(
-      '--env',
-      `VIRTUAL_ENV=${getContainerPath(process.env['VIRTUAL_ENV'])}`,
-    );
+    args.push('--volume', `${sandboxVenvPath}:${getContainerPath(virtualEnv)}`);
+    args.push('--env', `VIRTUAL_ENV=${getContainerPath(virtualEnv)}`);
   }
 
   // copy additional environment variables from SANDBOX_ENV