fix(sdk): prevent list directory path escapes

Author: c8dhjp4tyv-bit

common/src/testing/mocks/filesystem.ts

@@ -2,7 +2,7 @@ import { mock } from 'bun:test'
 
 import type { CodebuffFileSystem } from '../../types/filesystem'
 import type { Mock } from 'bun:test'
-import type { PathLike , Stats } from 'node:fs'
+import type { PathLike, Stats } from 'node:fs'
 
 export interface CreateMockFsOptions {
   files?: Record<string, string>
@@ -14,6 +14,7 @@ export interface CreateMockFsOptions {
     path: string,
     options?: { recursive?: boolean },
   ) => Promise<string | undefined>
+  realpathImpl?: (path: string) => Promise<string>
   statImpl?: (path: string) => Promise<Stats>
 }
 
@@ -31,6 +32,7 @@ export interface MockFsWithMocks {
       options?: { recursive?: boolean },
     ) => Promise<string | undefined>
   >
+  realpath: Mock<(path: PathLike) => Promise<string>>
   stat: Mock<(path: PathLike) => Promise<Stats>>
 }
 
@@ -43,6 +45,7 @@ export function createMockFs(options: CreateMockFsOptions = {}): MockFs {
     readdirImpl,
     writeFileImpl,
     mkdirImpl,
+    realpathImpl,
     statImpl,
   } = options
 
@@ -79,6 +82,20 @@ export function createMockFs(options: CreateMockFsOptions = {}): MockFs {
     return undefined
   }
 
+  const defaultRealpath = async (path: PathLike): Promise<string> => {
+    const pathStr = String(path)
+    const isKnownPath =
+      pathStr in writtenFiles ||
+      pathStr in directories ||
+      createdDirs.has(pathStr)
+
+    if (!isKnownPath) {
+      throw new Error(`Path not found: ${pathStr}`)
+    }
+
+    return pathStr
+  }
+
   const defaultStat = async (path: PathLike): Promise<Stats> => {
     const pathStr = String(path)
     const isFile = pathStr in writtenFiles
@@ -134,6 +151,10 @@ export function createMockFs(options: CreateMockFsOptions = {}): MockFs {
         mkdirImpl(String(path), opts)
     : defaultMkdir
 
+  const realpathFn = realpathImpl
+    ? async (path: PathLike) => realpathImpl(String(path))
+    : defaultRealpath
+
   const statFn = statImpl
     ? async (path: PathLike) => statImpl(String(path))
     : defaultStat
@@ -143,6 +164,7 @@ export function createMockFs(options: CreateMockFsOptions = {}): MockFs {
     readdir: mock(readdirFn),
     writeFile: mock(writeFileFn),
     mkdir: mock(mkdirFn),
+    realpath: mock(realpathFn),
     stat: mock(statFn),
   } as unknown as MockFs
 }
@@ -153,6 +175,7 @@ export function restoreMockFs(mockFs: MockFs): void {
   mocks.readdir.mockRestore()
   mocks.writeFile.mockRestore()
   mocks.mkdir.mockRestore()
+  mocks.realpath.mockRestore()
   mocks.stat.mockRestore()
 }
 
@@ -162,5 +185,6 @@ export function clearMockFs(mockFs: MockFs): void {
   mocks.readdir.mockClear()
   mocks.writeFile.mockClear()
   mocks.mkdir.mockClear()
+  mocks.realpath.mockClear()
   mocks.stat.mockClear()
 }

common/src/types/filesystem.ts

@@ -6,5 +6,11 @@ import type fs from 'fs'
  */
 export type CodebuffFileSystem = Pick<
   typeof fs.promises,
-  'mkdir' | 'readdir' | 'readFile' | 'stat' | 'unlink' | 'writeFile'
+  | 'mkdir'
+  | 'readdir'
+  | 'readFile'
+  | 'realpath'
+  | 'stat'
+  | 'unlink'
+  | 'writeFile'
 >

sdk/src/__tests__/list-directory.test.ts

@@ -0,0 +1,158 @@
+import { describe, expect, it, mock } from 'bun:test'
+
+import { listDirectory } from '../tools/list-directory'
+
+import type { CodebuffFileSystem } from '@codebuff/common/types/filesystem'
+import type { Dirent, PathLike } from 'node:fs'
+
+const PROJECT_ROOT = '/workspace/project'
+
+function createFs(realpaths: Record<string, string>) {
+  const readdir = mock(async (_path: PathLike) => {
+    return [
+      {
+        name: 'index.ts',
+        isDirectory: () => false,
+        isFile: () => true,
+      },
+    ] as Dirent[]
+  })
+
+  const fs = {
+    realpath: mock(async (path: PathLike) => {
+      const pathString = String(path)
+      return realpaths[pathString] ?? pathString
+    }),
+    readdir,
+  } as unknown as CodebuffFileSystem
+
+  return { fs, readdir }
+}
+
+describe('listDirectory', () => {
+  it('allows listing the project root itself', async () => {
+    const { fs, readdir } = createFs({
+      [PROJECT_ROOT]: PROJECT_ROOT,
+    })
+
+    const result = await listDirectory({
+      directoryPath: '.',
+      projectPath: PROJECT_ROOT,
+      fs,
+    })
+
+    expect(result[0]).toEqual({
+      type: 'json',
+      value: {
+        files: ['index.ts'],
+        directories: [],
+        path: '.',
+      },
+    })
+    expect(readdir).toHaveBeenCalledWith(PROJECT_ROOT, {
+      withFileTypes: true,
+    })
+  })
+
+  it('lists a directory inside the project and preserves the requested path', async () => {
+    const { fs, readdir } = createFs({
+      [PROJECT_ROOT]: PROJECT_ROOT,
+      [`${PROJECT_ROOT}/src`]: `${PROJECT_ROOT}/src`,
+    })
+
+    const result = await listDirectory({
+      directoryPath: 'src',
+      projectPath: PROJECT_ROOT,
+      fs,
+    })
+
+    expect(result).toEqual([
+      {
+        type: 'json',
+        value: {
+          files: ['index.ts'],
+          directories: [],
+          path: 'src',
+        },
+      },
+    ])
+    expect(readdir).toHaveBeenCalledWith(`${PROJECT_ROOT}/src`, {
+      withFileTypes: true,
+    })
+  })
+
+  it('rejects sibling paths that only share the project prefix', async () => {
+    const siblingPath = '/workspace/project-evil'
+    const { fs, readdir } = createFs({
+      [PROJECT_ROOT]: PROJECT_ROOT,
+      [siblingPath]: siblingPath,
+    })
+
+    const result = await listDirectory({
+      directoryPath: '../project-evil',
+      projectPath: PROJECT_ROOT,
+      fs,
+    })
+
+    expect(result).toEqual([
+      {
+        type: 'json',
+        value: {
+          errorMessage:
+            "Invalid path: Path '../project-evil' is outside the project directory.",
+        },
+      },
+    ])
+    expect(readdir).not.toHaveBeenCalled()
+  })
+
+  it('rejects the project parent directory', async () => {
+    const parentPath = '/workspace'
+    const { fs, readdir } = createFs({
+      [PROJECT_ROOT]: PROJECT_ROOT,
+      [parentPath]: parentPath,
+    })
+
+    const result = await listDirectory({
+      directoryPath: '..',
+      projectPath: PROJECT_ROOT,
+      fs,
+    })
+
+    expect(result).toEqual([
+      {
+        type: 'json',
+        value: {
+          errorMessage:
+            "Invalid path: Path '..' is outside the project directory.",
+        },
+      },
+    ])
+    expect(readdir).not.toHaveBeenCalled()
+  })
+
+  it('rejects directories that escape through a symlink', async () => {
+    const symlinkPath = `${PROJECT_ROOT}/link`
+    const { fs, readdir } = createFs({
+      [PROJECT_ROOT]: PROJECT_ROOT,
+      [symlinkPath]: '/outside',
+    })
+
+    const result = await listDirectory({
+      directoryPath: 'link',
+      projectPath: PROJECT_ROOT,
+      fs,
+    })
+
+    expect(result).toEqual([
+      {
+        type: 'json',
+        value: {
+          errorMessage:
+            "Invalid path: Path 'link' is outside the project directory.",
+        },
+      },
+    ])
+    expect(readdir).not.toHaveBeenCalled()
+  })
+})

sdk/src/tools/list-directory.ts

@@ -2,6 +2,7 @@ import * as path from 'path'
 
 import type { CodebuffToolOutput } from '@codebuff/common/tools/list'
 import type { CodebuffFileSystem } from '@codebuff/common/types/filesystem'
+import { isPathInside } from '@codebuff/common/util/path'
 
 export async function listDirectory(params: {
   directoryPath: string
@@ -11,9 +12,23 @@ export async function listDirectory(params: {
   const { directoryPath, projectPath, fs } = params
 
   try {
-    const resolvedPath = path.resolve(projectPath, directoryPath)
+    const projectRoot = path.resolve(projectPath)
+    const resolvedPath = path.resolve(projectRoot, directoryPath)
+    const realProjectRoot = await fs.realpath(projectRoot)
+    const realResolvedPath = await fs.realpath(resolvedPath)
 
-    const entries = await fs.readdir(resolvedPath, {
+    if (!isPathInside(realProjectRoot, realResolvedPath)) {
+      return [
+        {
+          type: 'json',
+          value: {
+            errorMessage: `Invalid path: Path '${directoryPath}' is outside the project directory.`,
+          },
+        },
+      ]
+    }
+
+    const entries = await fs.readdir(realResolvedPath, {
       withFileTypes: true,
     })