Sanitize session id by default, can add more strings

README.md

@@ -16,3 +16,17 @@ An example usage with Nette Framework (can be used with other frameworks or stan
 ```php
 $this->template->phpinfo = Html::el()->setHtml($this->phpInfo->getHtml());
 ```
+
+## Sanitization
+By default, session id (as returned by `session_id()`) will be sanitized and replaced by `[***]` in the output.
+This is to prevent some session hijacking attacks that would read the session id from the cookie value reflected in the `phpinfo()` output.
+You can disable that by calling `doNotSanitizeSessionId()` but it's totally not recommended. Do not disable that. Please.
+
+You can add own strings to be sanitized in the output with
+```php
+addSanitization(string $sanitize, ?string $with = null): self
+```
+If found, the string in `$sanitize` will be replaced with the string `$with`, if `$with` is null then the default `[***]` will be used instead.
+
+Some of the values in `phpinfo()` output are printed URL-encoded, so the `$sanitize` value will also be searched URL-encoded automatically.
+This means that both `foo,bar` and `foo%2Cbar` would be replaced.

src/PhpInfo.php

@@ -6,15 +6,57 @@
 class PhpInfo
 {
 
+	private bool $sanitizeSessionId = true;
+
+	private string $sanitizeWith = '[***]';
+
+	/** @var array<string, string> */
+	private array $sanitize = [];
+
+
 	public function getHtml(): string
 	{
 		$error = 'Cannot get phpinfo() output';
 		ob_start();
 		phpinfo();
 		$info = preg_replace('~^.*?(<table[^>]*>.*</table>).*$~s', '$1', ob_get_clean() ?: $error) ?? $error;
 		// Convert inline styles to classes defined in admin/info.css so we can drop CSP style-src 'unsafe-inline'
-		$info = str_replace('style="color: #', 'class="color-', $info);
+		$replacements['style="color: #'] = 'class="color-';
+		$sanitize = [];
+		if ($this->sanitizeSessionId && $this->getSessionId() !== null) {
+			$sanitize[$this->getSessionId()] = $this->sanitizeWith;
+		}
+		$sanitize = $this->sanitize + $sanitize;
+		foreach ($sanitize as $search => $replace) {
+			$replacements[$search] = $replace;
+			$replacements[urlencode($search)] = $replace;
+		}
+		$info = strtr($info, $replacements);
 		return sprintf('<div id="phpinfo">%s</div>', $info);
 	}
 
+
+	private function getSessionId(): ?string
+	{
+		return session_id() ?: null;
+	}
+
+
+	/**
+	 * WARNING: Not recommended, disabling session id sanitization may allow
+	 * session stealing attacks that read the cookie from the output of phpinfo().
+	 */
+	public function doNotSanitizeSessionId(): self
+	{
+		$this->sanitizeSessionId = false;
+		return $this;
+	}
+
+
+	public function addSanitization(string $sanitize, ?string $with = null): self
+	{
+		$this->sanitize[$sanitize] = $with ?? $this->sanitizeWith;
+		return $this;
+	}
+
 }

tests/PhpInfoTest.phpt

@@ -11,14 +11,71 @@ require __DIR__ . '/bootstrap.php';
 class PhpInfoTest extends TestCase
 {
 
+	private const SESSION_ID = 'foobar,baz';
+	private const WALDO_1337 = 'waldo-fred-1337';
+	private const WALDO_1338 = 'waldo-quux-1338';
+
+
+	protected function setUp(): void
+	{
+		$_SERVER['HTTP_WALDO_FRED'] = self::WALDO_1337;
+		$_SERVER['HTTP_COOKIE'] = 'PHPSESSID=' . urlencode(self::SESSION_ID);
+		$_COOKIE['PHPSESSID'] = self::SESSION_ID;
+
+		session_set_save_handler(new TestSessionHandler(self::SESSION_ID));
+		session_start();
+	}
+
+
+	protected function tearDown(): void
+	{
+		session_destroy();
+	}
+
+
 	public function testGetHtml(): void
 	{
-		$phpInfo = new PhpInfo();
-		$html = $phpInfo->getHtml();
+		$html = (new PhpInfo())->getHtml();
 		Assert::contains('<div id="phpinfo">', $html);
 		Assert::contains('disable_functions', $html);
 	}
 
+
+	public function testGetHtmlSessionIdSanitization(): void
+	{
+		$html = (new PhpInfo())->getHtml();
+		Assert::notContains(self::SESSION_ID, $html);
+		Assert::notContains(urlencode(self::SESSION_ID), $html);
+		Assert::contains('[***]', $html);
+	}
+
+
+	public function testGetHtmlSessionIdSanitizationCustomReplacement(): void
+	{
+		$phpInfo = new PhpInfo();
+		$phpInfo->addSanitization(self::SESSION_ID, 'yeah, sure');
+		Assert::contains('yeah, sure', $phpInfo->getHtml());
+	}
+
+
+	public function testGetHtmlDoNotSanitizeSessionIdButWhy(): void
+	{
+		$phpInfo = new PhpInfo();
+		$html = $phpInfo->doNotSanitizeSessionId()->getHtml();
+		Assert::contains(self::SESSION_ID, $html);
+		Assert::contains(urlencode(self::SESSION_ID), $html);
+	}
+
+
+	public function testGetHtmlAddSanitization(): void
+	{
+		$phpInfo = new PhpInfo();
+		Assert::contains(self::WALDO_1337, $phpInfo->getHtml());
+		$html = $phpInfo->addSanitization(self::WALDO_1337, self::WALDO_1338)->getHtml();
+		Assert::notContains(self::WALDO_1337, $html);
+		Assert::contains(self::WALDO_1338, $html);
+	}
+
 }
 
 (new PhpInfoTest())->run();

tests/TestSessionHandler.php

@@ -0,0 +1,61 @@
+<?php
+declare(strict_types = 1);
+
+namespace Spaze\PhpInfo;
+
+use SessionHandlerInterface;
+use SessionIdInterface;
+
+class TestSessionHandler implements SessionHandlerInterface, SessionIdInterface
+{
+
+	public function __construct(
+		private string $sessionId,
+		private array $data = [],
+	) {
+	}
+
+
+	public function create_sid(): string
+	{
+		return $this->sessionId;
+	}
+
+
+	public function open(string $path, string $name): bool
+	{
+		return true;
+	}
+
+
+	public function close(): bool
+	{
+		return true;
+	}
+
+
+	public function destroy(string $id): bool
+	{
+		return true;
+	}
+
+
+	public function gc(int $max_lifetime): int|false
+	{
+		return 0;
+	}
+
+
+	public function read(string $id): string|false
+	{
+		return $this->data[$id] ?? '';
+	}
+
+
+	public function write(string $id, string $data): bool
+	{
+		$this->data[$id] = $data;
+		return true;
+	}
+
+}

tests/bootstrap.php

@@ -1,8 +1,11 @@
 <?php
 declare(strict_types = 1);
 
+use Composer\Autoload\ClassLoader;
 use Tester\Environment;
 
-require __DIR__ . '/../vendor/autoload.php';
+/** @var ClassLoader $loader */
+$loader = require __DIR__ . '/../vendor/autoload.php';
+$loader->addPsr4('Spaze\\PhpInfo\\', __DIR__);
 
 Environment::setup();