Files
everything-claude-code/scripts/hooks/pre-bash-dev-server-block.js
Jamkris a7e51e8046 fix(hooks): close subshell bypass in pre-bash-dev-server-block
Before this commit the dev-server-block hook ran the leading-command
and dev-pattern check only against the top-level segments returned by
`splitShellSegments`, which doesn't split on `$(...)`, backticks, or
plain `(...)`. That left the policy bypassable by wrapping a dev
command in any of those constructs:

  $(npm run dev)
  `npm run dev`
  echo $(npm run dev)
  (npm run dev)

Each verified by piping a synthetic PreToolUse payload into the hook
on this branch: every form above returned exit 0 (allow) where a plain
`npm run dev` correctly returned exit 2 (block).

Fix: expand the check space before running the leading-command rule.
A small BFS walks the raw command, harvesting bodies from
`extractCommandSubstitutions` (`$(...)` and backticks) and from
`extractSubshellGroups` (plain `(...)`), then splits each harvested
body through `splitShellSegments` and feeds the result into the
existing `isBlockedDevSegment` check.

This preserves every existing allow case (`tmux new-session -d -s dev
"npm run dev"`, quoted-string mentions like `git commit -m "npm run
dev fix"`, `echo hi`) because the leading-command rule is unchanged —
only the set of segments it runs against grew.

Known limitation, not fixed here: `eval "$(echo npm run dev)"` still
slips through because the substitution body's leading command is
`echo`, and statically modeling echo's output to recover the executed
command is out of scope. The same class affects `gateguard-fact-force`
(via `eval "$(echo rm -rf /)"` etc.) and is best addressed in both
hooks together as a follow-up rather than as a one-off here.
2026-05-14 11:21:41 +09:00

224 lines
5.3 KiB
JavaScript
Executable File

#!/usr/bin/env node
'use strict';
const MAX_STDIN = 1024 * 1024;
const path = require('path');
const { splitShellSegments } = require('../lib/shell-split');
const {
extractCommandSubstitutions,
extractSubshellGroups
} = require('../lib/shell-substitution');
const DEV_COMMAND_WORDS = new Set([
'npm',
'pnpm',
'yarn',
'bun',
'npx',
'tmux'
]);
const SKIPPABLE_PREFIX_WORDS = new Set(['env', 'command', 'builtin', 'exec', 'noglob', 'sudo', 'nohup']);
const PREFIX_OPTION_VALUE_WORDS = {
env: new Set(['-u', '-C', '-S', '--unset', '--chdir', '--split-string']),
sudo: new Set([
'-u',
'-g',
'-h',
'-p',
'-r',
'-t',
'-C',
'--user',
'--group',
'--host',
'--prompt',
'--role',
'--type',
'--close-from'
])
};
function readToken(input, startIndex) {
let index = startIndex;
while (index < input.length && /\s/.test(input[index])) index += 1;
if (index >= input.length) return null;
let token = '';
let quote = null;
while (index < input.length) {
const ch = input[index];
if (quote) {
if (ch === quote) {
quote = null;
index += 1;
continue;
}
if (ch === '\\' && quote === '"' && index + 1 < input.length) {
token += input[index + 1];
index += 2;
continue;
}
token += ch;
index += 1;
continue;
}
if (ch === '"' || ch === "'") {
quote = ch;
index += 1;
continue;
}
if (/\s/.test(ch)) break;
if (ch === '\\' && index + 1 < input.length) {
token += input[index + 1];
index += 2;
continue;
}
token += ch;
index += 1;
}
return { token, end: index };
}
function shouldSkipOptionValue(wrapper, optionToken) {
if (!wrapper || !optionToken || optionToken.includes('=')) return false;
const optionSet = PREFIX_OPTION_VALUE_WORDS[wrapper];
return Boolean(optionSet && optionSet.has(optionToken));
}
function isOptionToken(token) {
return token.startsWith('-') && token.length > 1;
}
function normalizeCommandWord(token) {
if (!token) return '';
const base = path.basename(token).toLowerCase();
return base.replace(/\.(cmd|exe|bat)$/i, '');
}
function getLeadingCommandWord(segment) {
let index = 0;
let activeWrapper = null;
let skipNextValue = false;
while (index < segment.length) {
const parsed = readToken(segment, index);
if (!parsed) return null;
index = parsed.end;
const token = parsed.token;
if (!token) continue;
if (skipNextValue) {
skipNextValue = false;
continue;
}
if (token === '--') {
activeWrapper = null;
continue;
}
if (/^[A-Za-z_][A-Za-z0-9_]*=.*/.test(token)) continue;
const normalizedToken = normalizeCommandWord(token);
if (SKIPPABLE_PREFIX_WORDS.has(normalizedToken)) {
activeWrapper = normalizedToken;
continue;
}
if (activeWrapper && isOptionToken(token)) {
if (shouldSkipOptionValue(activeWrapper, token)) {
skipNextValue = true;
}
continue;
}
return normalizedToken;
}
return null;
}
let raw = '';
process.stdin.setEncoding('utf8');
process.stdin.on('data', chunk => {
if (raw.length < MAX_STDIN) {
const remaining = MAX_STDIN - raw.length;
raw += chunk.substring(0, remaining);
}
});
const TMUX_LAUNCHER = /^\s*tmux\s+(new|new-session|new-window|split-window)\b/;
const DEV_PATTERN = /\b(npm\s+run\s+dev|pnpm(?:\s+run)?\s+dev|yarn\s+dev|bun\s+run\s+dev)\b/;
/**
* Collect every command-line segment we should evaluate. Returns the top-level
* segments first, then segments harvested from `$(...)` / backtick command
* substitutions and plain `(...)` subshell groups, recursively.
*
* Without this expansion the leading-command and dev-pattern check below only
* sees the outermost command, so wrappers like `$(npm run dev)` and
* `(npm run dev)` (which still spawn a dev server) sneak past.
*/
function collectCheckSegments(cmd) {
const segments = [...splitShellSegments(cmd)];
const queue = [cmd];
const seen = new Set();
while (queue.length) {
const current = queue.shift();
if (seen.has(current)) continue;
seen.add(current);
for (const body of extractCommandSubstitutions(current)) {
for (const seg of splitShellSegments(body)) segments.push(seg);
queue.push(body);
}
for (const body of extractSubshellGroups(current)) {
for (const seg of splitShellSegments(body)) segments.push(seg);
queue.push(body);
}
}
return segments;
}
function isBlockedDevSegment(segment) {
const commandWord = getLeadingCommandWord(segment);
if (!commandWord || !DEV_COMMAND_WORDS.has(commandWord)) return false;
return DEV_PATTERN.test(segment) && !TMUX_LAUNCHER.test(segment);
}
process.stdin.on('end', () => {
try {
const input = JSON.parse(raw);
const cmd = String(input.tool_input?.command || '');
if (process.platform !== 'win32') {
const segments = collectCheckSegments(cmd);
const hasBlockedDev = segments.some(isBlockedDevSegment);
if (hasBlockedDev) {
console.error('[Hook] BLOCKED: Dev server must run in tmux for log access');
console.error('[Hook] Use: tmux new-session -d -s dev "npm run dev"');
console.error('[Hook] Then: tmux attach -t dev');
process.exit(2);
}
}
} catch {
// ignore parse errors and pass through
}
process.stdout.write(raw);
});