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7a1ad33 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 | /**
* @license
* Copyright 2025 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
/**
* Escapes a string for use in a regular expression.
*/
export function escapeRegex(text: string): string {
return text.replace(/[-[\]{}()*+?.,\\^$|#\s"]/g, '\\$&');
}
/**
* Basic validation for regular expressions to prevent common ReDoS patterns.
* This is a heuristic check and not a substitute for a full ReDoS scanner.
*/
export function isSafeRegExp(pattern: string): boolean {
try {
// 1. Ensure it's a valid regex
new RegExp(pattern);
} catch {
return false;
}
// 2. Limit length to prevent extremely long regexes
if (pattern.length > 2048) {
return false;
}
// 3. Heuristic: Check for nested quantifiers which are a primary source of ReDoS.
// Examples: (a+)+, (a|b)*, (.*)*, ([a-z]+)+
// We look for a group (...) followed by a quantifier (+, *, or {n,m})
// where the group itself contains a quantifier.
// This matches a '(' followed by some content including a quantifier, then ')',
// followed by another quantifier.
const nestedQuantifierPattern = /\([^)]*[*+?{].*\)[*+?{]/;
if (nestedQuantifierPattern.test(pattern)) {
return false;
}
return true;
}
/**
* Builds a list of args patterns for policy matching.
*
* This function handles the transformation of command prefixes and regexes into
* the internal argsPattern representation used by the PolicyEngine.
*
* @param argsPattern An optional raw regex string for arguments.
* @param commandPrefix An optional command prefix (or list of prefixes) to allow.
* @param commandRegex An optional command regex string to allow.
* @returns An array of string patterns (or undefined) for the PolicyEngine.
*/
export function buildArgsPatterns(
argsPattern?: string,
commandPrefix?: string | string[],
commandRegex?: string,
): Array<string | undefined> {
if (commandPrefix) {
const prefixes = Array.isArray(commandPrefix)
? commandPrefix
: [commandPrefix];
return prefixes.map((prefix) => {
// JSON.stringify safely encodes the prefix in quotes.
// We remove ONLY the trailing quote to match it as an open prefix string.
const encodedPrefix = JSON.stringify(prefix);
const openQuotePrefix = encodedPrefix.substring(
0,
encodedPrefix.length - 1,
);
// Escape the exact JSON literal segment we expect to see
const matchSegment = escapeRegex(`"command":${openQuotePrefix}`);
// We allow [\s], ["], or the specific sequence [\"] (for escaped quotes
// in JSON). We do NOT allow generic [\\], which would match "git\status"
// -> "gitstatus".
return `${matchSegment}(?:[\\s"]|\\\\")`;
});
}
if (commandRegex) {
return [`"command":"${commandRegex}`];
}
return [argsPattern];
}
/**
* Builds a regex pattern to match a specific parameter and value in tool arguments.
* This is used to narrow tool approvals to specific parameters.
*
* @param paramName The name of the parameter.
* @param value The value to match.
* @returns A regex string that matches "<paramName>":<value> in a JSON string.
*/
export function buildParamArgsPattern(
paramName: string,
value: unknown,
): string {
const encodedValue = JSON.stringify(value);
// We wrap the JSON string in escapeRegex and prepend/append \\0 to explicitly
// match top-level JSON properties generated by stableStringify, preventing
// argument injection bypass attacks.
return `\\\\0${escapeRegex(`"${paramName}":${encodedValue}`)}\\\\0`;
}
/**
* Builds a regex pattern to match a specific file path in tool arguments.
* This is used to narrow tool approvals for edit tools to specific files.
*
* @param filePath The relative path to the file.
* @returns A regex string that matches "file_path":"<path>" in a JSON string.
*/
export function buildFilePathArgsPattern(filePath: string): string {
return buildParamArgsPattern('file_path', filePath);
}
/**
* Builds a regex pattern to match a specific directory path in tool arguments.
* This is used to narrow tool approvals for list_directory tool.
*
* @param dirPath The path to the directory.
* @returns A regex string that matches "dir_path":"<path>" in a JSON string.
*/
export function buildDirPathArgsPattern(dirPath: string): string {
return buildParamArgsPattern('dir_path', dirPath);
}
/**
* Builds a regex pattern to match a specific "pattern" in tool arguments.
* This is used to narrow tool approvals for search tools like glob/grep to specific patterns.
*
* @param pattern The pattern to match.
* @returns A regex string that matches "pattern":"<pattern>" in a JSON string.
*/
export function buildPatternArgsPattern(pattern: string): string {
return buildParamArgsPattern('pattern', pattern);
}
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