From 820105e982e594b1bcee46ab866a7c70e5795b34 Mon Sep 17 00:00:00 2001 From: matt korwel Date: Fri, 25 Jul 2025 12:25:32 -0700 Subject: Safer Shell command Execution (#4795) Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com> Co-authored-by: N. Taylor Mullen --- packages/core/src/utils/shell-utils.test.ts | 583 ++++++++++++++++++++++++++++ packages/core/src/utils/shell-utils.ts | 288 ++++++++++++++ 2 files changed, 871 insertions(+) create mode 100644 packages/core/src/utils/shell-utils.test.ts create mode 100644 packages/core/src/utils/shell-utils.ts (limited to 'packages/core/src/utils') diff --git a/packages/core/src/utils/shell-utils.test.ts b/packages/core/src/utils/shell-utils.test.ts new file mode 100644 index 00000000..a3a2b6c2 --- /dev/null +++ b/packages/core/src/utils/shell-utils.test.ts @@ -0,0 +1,583 @@ +/** + * @license + * Copyright 2025 Google LLC + * SPDX-License-Identifier: Apache-2.0 + */ + +import { expect, describe, it, beforeEach } from 'vitest'; +import { + getCommandRoots, + isCommandAllowed, + stripShellWrapper, +} from './shell-utils.js'; +import { Config } from '../config/config.js'; + +describe('isCommandAllowed', () => { + let config: Config; + + beforeEach(() => { + config = { + getCoreTools: () => undefined, + getExcludeTools: () => undefined, + } as unknown as Config; + }); + + it('should allow a command if no restrictions are provided', async () => { + const result = isCommandAllowed('ls -l', config); + expect(result.allowed).toBe(true); + }); + + it('should allow a command if it is in the allowed list', async () => { + config = { + getCoreTools: () => ['ShellTool(ls -l)'], + getExcludeTools: () => undefined, + } as unknown as Config; + const result = isCommandAllowed('ls -l', config); + expect(result.allowed).toBe(true); + }); + + it('should block a command if it is not in the allowed list', async () => { + config = { + getCoreTools: () => ['ShellTool(ls -l)'], + getExcludeTools: () => undefined, + } as unknown as Config; + const result = isCommandAllowed('rm -rf /', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + "Command 'rm -rf /' is not in the allowed commands list", + ); + }); + + it('should block a command if it is in the blocked list', async () => { + config = { + getCoreTools: () => undefined, + getExcludeTools: () => ['ShellTool(rm -rf /)'], + } as unknown as Config; + const result = isCommandAllowed('rm -rf /', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + "Command 'rm -rf /' is blocked by configuration", + ); + }); + + it('should allow a command if it is not in the blocked list', async () => { + config = { + getCoreTools: () => undefined, + getExcludeTools: () => ['ShellTool(rm -rf /)'], + } as unknown as Config; + const result = isCommandAllowed('ls -l', config); + expect(result.allowed).toBe(true); + }); + + it('should block a command if it is in both the allowed and blocked lists', async () => { + config = { + getCoreTools: () => ['ShellTool(rm -rf /)'], + getExcludeTools: () => ['ShellTool(rm -rf /)'], + } as unknown as Config; + const result = isCommandAllowed('rm -rf /', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + "Command 'rm -rf /' is blocked by configuration", + ); + }); + + it('should allow any command when ShellTool is in coreTools without specific commands', async () => { + config = { + getCoreTools: () => ['ShellTool'], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed('any command', config); + expect(result.allowed).toBe(true); + }); + + it('should block any command when ShellTool is in excludeTools without specific commands', async () => { + config = { + getCoreTools: () => [], + getExcludeTools: () => ['ShellTool'], + } as unknown as Config; + const result = isCommandAllowed('any command', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + 'Shell tool is globally disabled in configuration', + ); + }); + + it('should allow a command if it is in the allowed list using the public-facing name', async () => { + config = { + getCoreTools: () => ['run_shell_command(ls -l)'], + getExcludeTools: () => undefined, + } as unknown as Config; + const result = isCommandAllowed('ls -l', config); + expect(result.allowed).toBe(true); + }); + + it('should block a command if it is in the blocked list using the public-facing name', async () => { + config = { + getCoreTools: () => undefined, + getExcludeTools: () => ['run_shell_command(rm -rf /)'], + } as unknown as Config; + const result = isCommandAllowed('rm -rf /', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + "Command 'rm -rf /' is blocked by configuration", + ); + }); + + it('should block any command when ShellTool is in excludeTools using the public-facing name', async () => { + config = { + getCoreTools: () => [], + getExcludeTools: () => ['run_shell_command'], + } as unknown as Config; + const result = isCommandAllowed('any command', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + 'Shell tool is globally disabled in configuration', + ); + }); + + it('should block any command if coreTools contains an empty ShellTool command list using the public-facing name', async () => { + config = { + getCoreTools: () => ['run_shell_command()'], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed('any command', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + "Command 'any command' is not in the allowed commands list", + ); + }); + + it('should block any command if coreTools contains an empty ShellTool command list', async () => { + config = { + getCoreTools: () => ['ShellTool()'], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed('any command', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + "Command 'any command' is not in the allowed commands list", + ); + }); + + it('should block a command with extra whitespace if it is in the blocked list', async () => { + config = { + getCoreTools: () => undefined, + getExcludeTools: () => ['ShellTool(rm -rf /)'], + } as unknown as Config; + const result = isCommandAllowed(' rm -rf / ', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + "Command 'rm -rf /' is blocked by configuration", + ); + }); + + it('should allow any command when ShellTool is in present with specific commands', async () => { + config = { + getCoreTools: () => ['ShellTool', 'ShellTool(ls)'], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed('any command', config); + expect(result.allowed).toBe(true); + }); + + it('should block a command on the blocklist even with a wildcard allow', async () => { + config = { + getCoreTools: () => ['ShellTool'], + getExcludeTools: () => ['ShellTool(rm -rf /)'], + } as unknown as Config; + const result = isCommandAllowed('rm -rf /', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + "Command 'rm -rf /' is blocked by configuration", + ); + }); + + it('should allow a command that starts with an allowed command prefix', async () => { + config = { + getCoreTools: () => ['ShellTool(gh issue edit)'], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed( + 'gh issue edit 1 --add-label "kind/feature"', + config, + ); + expect(result.allowed).toBe(true); + }); + + it('should allow a command that starts with an allowed command prefix using the public-facing name', async () => { + config = { + getCoreTools: () => ['run_shell_command(gh issue edit)'], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed( + 'gh issue edit 1 --add-label "kind/feature"', + config, + ); + expect(result.allowed).toBe(true); + }); + + it('should not allow a command that starts with an allowed command prefix but is chained with another command', async () => { + config = { + getCoreTools: () => ['run_shell_command(gh issue edit)'], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed('gh issue edit&&rm -rf /', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + "Command 'rm -rf /' is not in the allowed commands list", + ); + }); + + it('should not allow a command that is a prefix of an allowed command', async () => { + config = { + getCoreTools: () => ['run_shell_command(gh issue edit)'], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed('gh issue', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + "Command 'gh issue' is not in the allowed commands list", + ); + }); + + it('should not allow a command that is a prefix of a blocked command', async () => { + config = { + getCoreTools: () => [], + getExcludeTools: () => ['run_shell_command(gh issue edit)'], + } as unknown as Config; + const result = isCommandAllowed('gh issue', config); + expect(result.allowed).toBe(true); + }); + + it('should not allow a command that is chained with a pipe', async () => { + config = { + getCoreTools: () => ['run_shell_command(gh issue list)'], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed('gh issue list | rm -rf /', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + "Command 'rm -rf /' is not in the allowed commands list", + ); + }); + + it('should not allow a command that is chained with a semicolon', async () => { + config = { + getCoreTools: () => ['run_shell_command(gh issue list)'], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed('gh issue list; rm -rf /', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + "Command 'rm -rf /' is not in the allowed commands list", + ); + }); + + it('should block a chained command if any part is blocked', async () => { + config = { + getCoreTools: () => ['run_shell_command(echo "hello")'], + getExcludeTools: () => ['run_shell_command(rm)'], + } as unknown as Config; + const result = isCommandAllowed('echo "hello" && rm -rf /', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + "Command 'rm -rf /' is blocked by configuration", + ); + }); + + it('should block a command if its prefix is on the blocklist, even if the command itself is on the allowlist', async () => { + config = { + getCoreTools: () => ['run_shell_command(git push)'], + getExcludeTools: () => ['run_shell_command(git)'], + } as unknown as Config; + const result = isCommandAllowed('git push', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + "Command 'git push' is blocked by configuration", + ); + }); + + it('should be case-sensitive in its matching', async () => { + config = { + getCoreTools: () => ['run_shell_command(echo)'], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed('ECHO "hello"', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + 'Command \'ECHO "hello"\' is not in the allowed commands list', + ); + }); + + it('should correctly handle commands with extra whitespace around chaining operators', async () => { + config = { + getCoreTools: () => ['run_shell_command(ls -l)'], + getExcludeTools: () => ['run_shell_command(rm)'], + } as unknown as Config; + const result = isCommandAllowed('ls -l ; rm -rf /', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + "Command 'rm -rf /' is blocked by configuration", + ); + }); + + it('should allow a chained command if all parts are allowed', async () => { + config = { + getCoreTools: () => [ + 'run_shell_command(echo)', + 'run_shell_command(ls -l)', + ], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed('echo "hello" && ls -l', config); + expect(result.allowed).toBe(true); + }); + + it('should block a command with command substitution using backticks', async () => { + config = { + getCoreTools: () => ['run_shell_command(echo)'], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed('echo `rm -rf /`', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + 'Command substitution using $(), <(), or >() is not allowed for security reasons', + ); + }); + + it('should block a command with command substitution using $()', async () => { + config = { + getCoreTools: () => ['run_shell_command(echo)'], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed('echo $(rm -rf /)', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + 'Command substitution using $(), <(), or >() is not allowed for security reasons', + ); + }); + + it('should block a command with process substitution using <()', async () => { + config = { + getCoreTools: () => ['run_shell_command(diff)'], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed('diff <(ls) <(ls -a)', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + 'Command substitution using $(), <(), or >() is not allowed for security reasons', + ); + }); + + it('should allow a command with I/O redirection', async () => { + config = { + getCoreTools: () => ['run_shell_command(echo)'], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed('echo "hello" > file.txt', config); + expect(result.allowed).toBe(true); + }); + + it('should not allow a command that is chained with a double pipe', async () => { + config = { + getCoreTools: () => ['run_shell_command(gh issue list)'], + getExcludeTools: () => [], + } as unknown as Config; + const result = isCommandAllowed('gh issue list || rm -rf /', config); + expect(result.allowed).toBe(false); + expect(result.reason).toBe( + "Command 'rm -rf /' is not in the allowed commands list", + ); + }); +}); + +describe('getCommandRoots', () => { + it('should return a single command', () => { + const result = getCommandRoots('ls -l'); + expect(result).toEqual(['ls']); + }); + + it('should return multiple commands', () => { + const result = getCommandRoots('ls -l | grep "test"'); + expect(result).toEqual(['ls', 'grep']); + }); + + it('should handle multiple commands with &&', () => { + const result = getCommandRoots('npm run build && npm test'); + expect(result).toEqual(['npm', 'npm']); + }); + + it('should handle multiple commands with ;', () => { + const result = getCommandRoots('echo "hello"; echo "world"'); + expect(result).toEqual(['echo', 'echo']); + }); + + it('should handle a mix of operators', () => { + const result = getCommandRoots( + 'cat package.json | grep "version" && echo "done"', + ); + expect(result).toEqual(['cat', 'grep', 'echo']); + }); + + it('should handle commands with paths', () => { + const result = getCommandRoots('/usr/local/bin/node script.js'); + expect(result).toEqual(['node']); + }); + + it('should return an empty array for an empty string', () => { + const result = getCommandRoots(''); + expect(result).toEqual([]); + }); +}); + +describe('stripShellWrapper', () => { + it('should strip sh -c from the beginning of the command', () => { + const result = stripShellWrapper('sh -c "ls -l"'); + expect(result).toEqual('ls -l'); + }); + + it('should strip bash -c from the beginning of the command', () => { + const result = stripShellWrapper('bash -c "ls -l"'); + expect(result).toEqual('ls -l'); + }); + + it('should strip zsh -c from the beginning of the command', () => { + const result = stripShellWrapper('zsh -c "ls -l"'); + expect(result).toEqual('ls -l'); + }); + + it('should not strip anything if the command does not start with a shell wrapper', () => { + const result = stripShellWrapper('ls -l'); + expect(result).toEqual('ls -l'); + }); + + it('should handle extra whitespace', () => { + const result = stripShellWrapper(' sh -c "ls -l" '); + expect(result).toEqual('ls -l'); + }); + + it('should handle commands without quotes', () => { + const result = stripShellWrapper('sh -c ls -l'); + expect(result).toEqual('ls -l'); + }); + + it('should strip cmd.exe /c from the beginning of the command', () => { + const result = stripShellWrapper('cmd.exe /c "dir"'); + expect(result).toEqual('dir'); + }); +}); + +describe('getCommandRoots', () => { + it('should handle multiple commands with &', () => { + const result = getCommandRoots('echo "hello" & echo "world"'); + expect(result).toEqual(['echo', 'echo']); + }); +}); + +describe('command substitution', () => { + let config: Config; + + beforeEach(() => { + config = { + getCoreTools: () => ['run_shell_command(echo)', 'run_shell_command(gh)'], + getExcludeTools: () => [], + } as unknown as Config; + }); + + it('should block unquoted command substitution `$(...)`', () => { + const result = isCommandAllowed('echo $(pwd)', config); + expect(result.allowed).toBe(false); + }); + + it('should block unquoted command substitution `<(...)`', () => { + const result = isCommandAllowed('echo <(pwd)', config); + expect(result.allowed).toBe(false); + }); + + it('should allow command substitution in single quotes', () => { + const result = isCommandAllowed("echo '$(pwd)'", config); + expect(result.allowed).toBe(true); + }); + + it('should allow backticks in single quotes', () => { + const result = isCommandAllowed("echo '`rm -rf /`'", config); + expect(result.allowed).toBe(true); + }); + + it('should block command substitution in double quotes', () => { + const result = isCommandAllowed('echo "$(pwd)"', config); + expect(result.allowed).toBe(false); + }); + + it('should allow escaped command substitution', () => { + const result = isCommandAllowed('echo \\$(pwd)', config); + expect(result.allowed).toBe(true); + }); + + it('should allow complex commands with quoted substitution-like patterns', () => { + const command = + "gh pr comment 4795 --body 'This is a test comment with $(pwd) style text'"; + const result = isCommandAllowed(command, config); + expect(result.allowed).toBe(true); + }); + + it('should block complex commands with unquoted substitution-like patterns', () => { + const command = + 'gh pr comment 4795 --body "This is a test comment with $(pwd) style text"'; + const result = isCommandAllowed(command, config); + expect(result.allowed).toBe(false); + }); + + it('should allow a command with markdown content using proper quoting', () => { + // Simple test with safe content in single quotes + const result = isCommandAllowed( + "gh pr comment 4795 --body 'This is safe markdown content'", + config, + ); + expect(result.allowed).toBe(true); + }); +}); + +describe('getCommandRoots with quote handling', () => { + it('should correctly parse a simple command', () => { + const result = getCommandRoots('git status'); + expect(result).toEqual(['git']); + }); + + it('should correctly parse a command with a quoted argument', () => { + const result = getCommandRoots('git commit -m "feat: new feature"'); + expect(result).toEqual(['git']); + }); + + it('should correctly parse a command with single quotes', () => { + const result = getCommandRoots("echo 'hello world'"); + expect(result).toEqual(['echo']); + }); + + it('should correctly parse a chained command with quotes', () => { + const result = getCommandRoots('echo "hello" && git status'); + expect(result).toEqual(['echo', 'git']); + }); + + it('should correctly parse a complex chained command', () => { + const result = getCommandRoots( + 'git commit -m "feat: new feature" && echo "done"', + ); + expect(result).toEqual(['git', 'echo']); + }); + + it('should handle escaped quotes', () => { + const result = getCommandRoots('echo "this is a "quote""'); + expect(result).toEqual(['echo']); + }); + + it('should handle commands with no spaces', () => { + const result = getCommandRoots('command'); + expect(result).toEqual(['command']); + }); + + it('should handle multiple separators', () => { + const result = getCommandRoots('a;b|c&&d||e&f'); + expect(result).toEqual(['a', 'b', 'c', 'd', 'e', 'f']); + }); +}); diff --git a/packages/core/src/utils/shell-utils.ts b/packages/core/src/utils/shell-utils.ts new file mode 100644 index 00000000..7008fb1b --- /dev/null +++ b/packages/core/src/utils/shell-utils.ts @@ -0,0 +1,288 @@ +/** + * @license + * Copyright 2025 Google LLC + * SPDX-License-Identifier: Apache-2.0 + */ + +import { Config } from '../config/config.js'; + +/** + * Splits a shell command into a list of individual commands, respecting quotes. + * This is used to separate chained commands (e.g., using &&, ||, ;). + * @param command The shell command string to parse + * @returns An array of individual command strings + */ +export function splitCommands(command: string): string[] { + const commands: string[] = []; + let currentCommand = ''; + let inSingleQuotes = false; + let inDoubleQuotes = false; + let i = 0; + + while (i < command.length) { + const char = command[i]; + const nextChar = command[i + 1]; + + if (char === '\\' && i < command.length - 1) { + currentCommand += char + command[i + 1]; + i += 2; + continue; + } + + if (char === "'" && !inDoubleQuotes) { + inSingleQuotes = !inSingleQuotes; + } else if (char === '"' && !inSingleQuotes) { + inDoubleQuotes = !inDoubleQuotes; + } + + if (!inSingleQuotes && !inDoubleQuotes) { + if ( + (char === '&' && nextChar === '&') || + (char === '|' && nextChar === '|') + ) { + commands.push(currentCommand.trim()); + currentCommand = ''; + i++; // Skip the next character + } else if (char === ';' || char === '&' || char === '|') { + commands.push(currentCommand.trim()); + currentCommand = ''; + } else { + currentCommand += char; + } + } else { + currentCommand += char; + } + i++; + } + + if (currentCommand.trim()) { + commands.push(currentCommand.trim()); + } + + return commands.filter(Boolean); // Filter out any empty strings +} + +/** + * Extracts the root command from a given shell command string. + * This is used to identify the base command for permission checks. + * @param command The shell command string to parse + * @returns The root command name, or undefined if it cannot be determined + * @example getCommandRoot("ls -la /tmp") returns "ls" + * @example getCommandRoot("git status && npm test") returns "git" + */ +export function getCommandRoot(command: string): string | undefined { + const trimmedCommand = command.trim(); + if (!trimmedCommand) { + return undefined; + } + + // This regex is designed to find the first "word" of a command, + // while respecting quotes. It looks for a sequence of non-whitespace + // characters that are not inside quotes. + const match = trimmedCommand.match(/^"([^"]+)"|^'([^']+)'|^(\S+)/); + if (match) { + // The first element in the match array is the full match. + // The subsequent elements are the capture groups. + // We prefer a captured group because it will be unquoted. + const commandRoot = match[1] || match[2] || match[3]; + if (commandRoot) { + // If the command is a path, return the last component. + return commandRoot.split(/[\\/]/).pop(); + } + } + + return undefined; +} + +export function getCommandRoots(command: string): string[] { + if (!command) { + return []; + } + return splitCommands(command) + .map((c) => getCommandRoot(c)) + .filter((c): c is string => !!c); +} + +export function stripShellWrapper(command: string): string { + const pattern = /^\s*(?:sh|bash|zsh|cmd.exe)\s+(?:\/c|-c)\s+/; + const match = command.match(pattern); + if (match) { + let newCommand = command.substring(match[0].length).trim(); + if ( + (newCommand.startsWith('"') && newCommand.endsWith('"')) || + (newCommand.startsWith("'") && newCommand.endsWith("'")) + ) { + newCommand = newCommand.substring(1, newCommand.length - 1); + } + return newCommand; + } + return command.trim(); +} + +/** + * Detects command substitution patterns in a shell command, following bash quoting rules: + * - Single quotes ('): Everything literal, no substitution possible + * - Double quotes ("): Command substitution with $() and backticks unless escaped with \ + * - No quotes: Command substitution with $(), <(), and backticks + * @param command The shell command string to check + * @returns true if command substitution would be executed by bash + */ +export function detectCommandSubstitution(command: string): boolean { + let inSingleQuotes = false; + let inDoubleQuotes = false; + let inBackticks = false; + let i = 0; + + while (i < command.length) { + const char = command[i]; + const nextChar = command[i + 1]; + + // Handle escaping - only works outside single quotes + if (char === '\\' && !inSingleQuotes) { + i += 2; // Skip the escaped character + continue; + } + + // Handle quote state changes + if (char === "'" && !inDoubleQuotes && !inBackticks) { + inSingleQuotes = !inSingleQuotes; + } else if (char === '"' && !inSingleQuotes && !inBackticks) { + inDoubleQuotes = !inDoubleQuotes; + } else if (char === '`' && !inSingleQuotes) { + // Backticks work outside single quotes (including in double quotes) + inBackticks = !inBackticks; + } + + // Check for command substitution patterns that would be executed + if (!inSingleQuotes) { + // $(...) command substitution - works in double quotes and unquoted + if (char === '$' && nextChar === '(') { + return true; + } + + // <(...) process substitution - works unquoted only (not in double quotes) + if (char === '<' && nextChar === '(' && !inDoubleQuotes && !inBackticks) { + return true; + } + + // Backtick command substitution - check for opening backtick + // (We track the state above, so this catches the start of backtick substitution) + if (char === '`' && !inBackticks) { + return true; + } + } + + i++; + } + + return false; +} + +/** + * Determines whether a given shell command is allowed to execute based on + * the tool's configuration including allowlists and blocklists. + * @param command The shell command string to validate + * @param config The application configuration + * @returns An object with 'allowed' boolean and optional 'reason' string if not allowed + */ +export function isCommandAllowed( + command: string, + config: Config, +): { allowed: boolean; reason?: string } { + // 0. Disallow command substitution + // Parse the command to check for unquoted/unescaped command substitution + const hasCommandSubstitution = detectCommandSubstitution(command); + if (hasCommandSubstitution) { + return { + allowed: false, + reason: + 'Command substitution using $(), <(), or >() is not allowed for security reasons', + }; + } + + const SHELL_TOOL_NAMES = ['run_shell_command', 'ShellTool']; + + const normalize = (cmd: string): string => cmd.trim().replace(/\s+/g, ' '); + + /** + * Checks if a command string starts with a given prefix, ensuring it's a + * whole word match (i.e., followed by a space or it's an exact match). + * e.g., `isPrefixedBy('npm install', 'npm')` -> true + * e.g., `isPrefixedBy('npm', 'npm')` -> true + * e.g., `isPrefixedBy('npminstall', 'npm')` -> false + */ + const isPrefixedBy = (cmd: string, prefix: string): boolean => { + if (!cmd.startsWith(prefix)) { + return false; + } + return cmd.length === prefix.length || cmd[prefix.length] === ' '; + }; + + /** + * Extracts and normalizes shell commands from a list of tool strings. + * e.g., 'ShellTool("ls -l")' becomes 'ls -l' + */ + const extractCommands = (tools: string[]): string[] => + tools.flatMap((tool) => { + for (const toolName of SHELL_TOOL_NAMES) { + if (tool.startsWith(`${toolName}(`) && tool.endsWith(')')) { + return [normalize(tool.slice(toolName.length + 1, -1))]; + } + } + return []; + }); + + const coreTools = config.getCoreTools() || []; + const excludeTools = config.getExcludeTools() || []; + + // 1. Check if the shell tool is globally disabled. + if (SHELL_TOOL_NAMES.some((name) => excludeTools.includes(name))) { + return { + allowed: false, + reason: 'Shell tool is globally disabled in configuration', + }; + } + + const blockedCommands = new Set(extractCommands(excludeTools)); + const allowedCommands = new Set(extractCommands(coreTools)); + + const hasSpecificAllowedCommands = allowedCommands.size > 0; + const isWildcardAllowed = SHELL_TOOL_NAMES.some((name) => + coreTools.includes(name), + ); + + const commandsToValidate = splitCommands(command).map(normalize); + + const blockedCommandsArr = [...blockedCommands]; + + for (const cmd of commandsToValidate) { + // 2. Check if the command is on the blocklist. + const isBlocked = blockedCommandsArr.some((blocked) => + isPrefixedBy(cmd, blocked), + ); + if (isBlocked) { + return { + allowed: false, + reason: `Command '${cmd}' is blocked by configuration`, + }; + } + + // 3. If in strict allow-list mode, check if the command is permitted. + const isStrictAllowlist = hasSpecificAllowedCommands && !isWildcardAllowed; + const allowedCommandsArr = [...allowedCommands]; + if (isStrictAllowlist) { + const isAllowed = allowedCommandsArr.some((allowed) => + isPrefixedBy(cmd, allowed), + ); + if (!isAllowed) { + return { + allowed: false, + reason: `Command '${cmd}' is not in the allowed commands list`, + }; + } + } + } + + // 4. If all checks pass, the command is allowed. + return { allowed: true }; +} -- cgit v1.2.3