|
| 1 | +<?php |
| 2 | + |
| 3 | +/* |
| 4 | + * This file is part of the Symfony package. |
| 5 | + * |
| 6 | + * (c) Fabien Potencier <fabien@symfony.com> |
| 7 | + * |
| 8 | + * For the full copyright and license information, please view the LICENSE |
| 9 | + * file that was distributed with this source code. |
| 10 | + */ |
| 11 | + |
| 12 | +namespace Symfony\Bundle\WebProfilerBundle\Csp; |
| 13 | + |
| 14 | +use Symfony\Component\HttpFoundation\Request; |
| 15 | +use Symfony\Component\HttpFoundation\Response; |
| 16 | + |
| 17 | +/** |
| 18 | + * Handles Content-Security-Policy HTTP header for the WebProfiler Bundle. |
| 19 | + * |
| 20 | + * @author Romain Neutron <imprec@gmail.com> |
| 21 | + * |
| 22 | + * @internal |
| 23 | + */ |
| 24 | +class ContentSecurityPolicyHandler |
| 25 | +{ |
| 26 | + private $nonceGenerator; |
| 27 | + private $cspDisabled = false; |
| 28 | + |
| 29 | + public function __construct(NonceGenerator $nonceGenerator) |
| 30 | + { |
| 31 | + $this->nonceGenerator = $nonceGenerator; |
| 32 | + } |
| 33 | + |
| 34 | + /** |
| 35 | + * Returns an array of nonces to be used in Twig templates and Content-Security-Policy headers. |
| 36 | + * |
| 37 | + * Nonce can be provided by; |
| 38 | + * - The request - In case HTML content is fetched via AJAX and inserted in DOM, it must use the same nonce as origin |
| 39 | + * - The response - A call to getNonces() has already been done previously. Same nonce are returned |
| 40 | + * - They are otherwise randomly generated |
| 41 | + * |
| 42 | + * @return array |
| 43 | + */ |
| 44 | + public function getNonces(Request $request, Response $response) |
| 45 | + { |
| 46 | + if ($request->headers->has('X-SymfonyProfiler-Script-Nonce') && $request->headers->has('X-SymfonyProfiler-Style-Nonce')) { |
| 47 | + return array( |
| 48 | + 'csp_script_nonce' => $request->headers->get('X-SymfonyProfiler-Script-Nonce'), |
| 49 | + 'csp_style_nonce' => $request->headers->get('X-SymfonyProfiler-Style-Nonce'), |
| 50 | + ); |
| 51 | + } |
| 52 | + |
| 53 | + if ($response->headers->has('X-SymfonyProfiler-Script-Nonce') && $response->headers->has('X-SymfonyProfiler-Style-Nonce')) { |
| 54 | + return array( |
| 55 | + 'csp_script_nonce' => $response->headers->get('X-SymfonyProfiler-Script-Nonce'), |
| 56 | + 'csp_style_nonce' => $response->headers->get('X-SymfonyProfiler-Style-Nonce'), |
| 57 | + ); |
| 58 | + } |
| 59 | + |
| 60 | + $nonces = array( |
| 61 | + 'csp_script_nonce' => $this->generateNonce(), |
| 62 | + 'csp_style_nonce' => $this->generateNonce(), |
| 63 | + ); |
| 64 | + |
| 65 | + $response->headers->set('X-SymfonyProfiler-Script-Nonce', $nonces['csp_script_nonce']); |
| 66 | + $response->headers->set('X-SymfonyProfiler-Style-Nonce', $nonces['csp_style_nonce']); |
| 67 | + |
| 68 | + return $nonces; |
| 69 | + } |
| 70 | + |
| 71 | + /** |
| 72 | + * Disables Content-Security-Policy. |
| 73 | + * |
| 74 | + * All related headers will be removed. |
| 75 | + */ |
| 76 | + public function disableCsp() |
| 77 | + { |
| 78 | + $this->cspDisabled = true; |
| 79 | + } |
| 80 | + |
| 81 | + /** |
| 82 | + * Cleanup temporary headers and updates Content-Security-Policy headers. |
| 83 | + * |
| 84 | + * @return array Nonces used by the bundle in Content-Security-Policy header |
| 85 | + */ |
| 86 | + public function updateResponseHeaders(Request $request, Response $response) |
| 87 | + { |
| 88 | + if ($this->cspDisabled) { |
| 89 | + $this->removeCspHeaders($response); |
| 90 | + |
| 91 | + return array(); |
| 92 | + } |
| 93 | + |
| 94 | + $nonces = $this->getNonces($request, $response); |
| 95 | + $this->cleanHeaders($response); |
| 96 | + $this->updateCspHeaders($response, $nonces); |
| 97 | + |
| 98 | + return $nonces; |
| 99 | + } |
| 100 | + |
| 101 | + private function cleanHeaders(Response $response) |
| 102 | + { |
| 103 | + $response->headers->remove('X-SymfonyProfiler-Script-Nonce'); |
| 104 | + $response->headers->remove('X-SymfonyProfiler-Style-Nonce'); |
| 105 | + } |
| 106 | + |
| 107 | + private function removeCspHeaders(Response $response) |
| 108 | + { |
| 109 | + $response->headers->remove('X-Content-Security-Policy'); |
| 110 | + $response->headers->remove('Content-Security-Policy'); |
| 111 | + } |
| 112 | + |
| 113 | + /** |
| 114 | + * Updates Content-Security-Policy headers in a response. |
| 115 | + * |
| 116 | + * @return array |
| 117 | + */ |
| 118 | + private function updateCspHeaders(Response $response, array $nonces = array()) |
| 119 | + { |
| 120 | + $nonces = array_replace(array( |
| 121 | + 'csp_script_nonce' => $this->generateNonce(), |
| 122 | + 'csp_style_nonce' => $this->generateNonce(), |
| 123 | + ), $nonces); |
| 124 | + |
| 125 | + $ruleIsSet = false; |
| 126 | + |
| 127 | + $headers = $this->getCspHeaders($response); |
| 128 | + |
| 129 | + foreach ($headers as $header => $directives) { |
| 130 | + foreach (array('script-src' => 'csp_script_nonce', 'style-src' => 'csp_style_nonce') as $type => $tokenName) { |
| 131 | + if ($this->authorizesInline($directives, $type)) { |
| 132 | + continue; |
| 133 | + } |
| 134 | + if (!isset($headers[$header][$type])) { |
| 135 | + if (isset($headers[$header]['default-src'])) { |
| 136 | + $headers[$header][$type] = $headers[$header]['default-src']; |
| 137 | + } else { |
| 138 | + $headers[$header][$type] = array(); |
| 139 | + } |
| 140 | + } |
| 141 | + $ruleIsSet = true; |
| 142 | + if (!in_array('\'unsafe-inline\'', $headers[$header][$type], true)) { |
| 143 | + $headers[$header][$type][] = '\'unsafe-inline\''; |
| 144 | + } |
| 145 | + $headers[$header][$type][] = sprintf('\'nonce-%s\'', $nonces[$tokenName]); |
| 146 | + } |
| 147 | + } |
| 148 | + |
| 149 | + if (!$ruleIsSet) { |
| 150 | + return $nonces; |
| 151 | + } |
| 152 | + |
| 153 | + foreach ($headers as $header => $directives) { |
| 154 | + $response->headers->set($header, $this->generateCspHeader($directives)); |
| 155 | + } |
| 156 | + |
| 157 | + return $nonces; |
| 158 | + } |
| 159 | + |
| 160 | + /** |
| 161 | + * Generates a valid Content-Security-Policy nonce. |
| 162 | + * |
| 163 | + * @return string |
| 164 | + */ |
| 165 | + private function generateNonce() |
| 166 | + { |
| 167 | + return $this->nonceGenerator->generate(); |
| 168 | + } |
| 169 | + |
| 170 | + /** |
| 171 | + * Converts a directive set array into Content-Security-Policy header. |
| 172 | + * |
| 173 | + * @param array $directives The directive set |
| 174 | + * |
| 175 | + * @return string The Content-Security-Policy header |
| 176 | + */ |
| 177 | + private function generateCspHeader(array $directives) |
| 178 | + { |
| 179 | + return array_reduce(array_keys($directives), function ($res, $name) use ($directives) { |
| 180 | + return ($res !== '' ? $res.'; ' : '').sprintf('%s %s', $name, implode(' ', $directiv
97AE
es[$name])); |
| 181 | + }, ''); |
| 182 | + } |
| 183 | + |
| 184 | + /** |
| 185 | + * Converts a Content-Security-Policy header value into a directive set array. |
| 186 | + * |
| 187 | + * @param string $header The header value |
| 188 | + * |
| 189 | + * @return array The directive set |
| 190 | + */ |
| 191 | + private function parseDirectives($header) |
| 192 | + { |
| 193 | + $directives = array(); |
| 194 | + |
| 195 | + foreach (explode(';', $header) as $directive) { |
| 196 | + $parts = explode(' ', trim($directive)); |
| 197 | + if (count($parts) < 1) { |
| 198 | + continue; |
| 199 | + } |
| 200 | + $name = array_shift($parts); |
| 201 | + $directives[$name] = $parts; |
| 202 | + } |
| 203 | + |
| 204 | + return $directives; |
| 205 | + } |
| 206 | + |
| 207 | + /** |
| 208 | + * Detects if the 'unsafe-inline' is prevented for a directive within the directive set. |
| 209 | + * |
| 210 | + * @param array $directivesSet The directive set |
| 211 | + * @param string $type The name of the directive to check |
| 212 | + * |
| 213 | + * @return bool |
| 214 | + */ |
| 215 | + private function authorizesInline(array $directivesSet, $type) |
| 216 | + { |
| 217 | + if (isset($directivesSet[$type])) { |
| 218 | + $directives = $directivesSet[$type]; |
| 219 | + } elseif (isset($directivesSet['default-src'])) { |
| 220 | + $directives = $directivesSet['default-src']; |
| 221 | + } else { |
| 222 | + return false; |
| 223 | + } |
| 224 | + |
| 225 | + return in_array('\'unsafe-inline\'', $directives, true) && !$this->hasHashOrNonce($directives); |
| 226 | + } |
| 227 | + |
| 228 | + private function hasHashOrNonce(array $directives) |
| 229 | + { |
| 230 | + foreach ($directives as $directive) { |
| 231 | + if ('\'' !== substr($directive, -1)) { |
| 232 | + continue; |
| 233 | + } |
| 234 | + if ('\'nonce-' === substr($directive, 0, 7)) { |
| 235 | + return true; |
| 236 | + } |
| 237 | + if (in_array(substr($directive, 0, 8), array('\'sha256-', '\'sha384-', '\'sha512-'), true)) { |
| 238 | + return true; |
| 239 | + } |
| 240 | + } |
| 241 | + |
| 242 | + return false; |
| 243 | + } |
| 244 | + |
| 245 | + /** |
| 246 | + * Retrieves the Content-Security-Policy headers (either X-Content-Security-Policy or Content-Security-Policy) from |
| 247 | + * a response. |
| 248 | + * |
| 249 | + * @return array An associative array of headers |
| 250 | + */ |
| 251 | + private function getCspHeaders(Response $response) |
| 252 | + { |
| 253 | + $headers = array(); |
| 254 | + |
| 255 | + if ($response->headers->has('Content-Security-Policy')) { |
| 256 | + $headers['Content-Security-Policy'] = $this->parseDirectives($response->headers->get('Content-Security-Policy')); |
| 257 | + } |
| 258 | + |
| 259 | + if ($response->headers->has('X-Content-Security-Policy')) { |
| 260 | + $headers['X-Content-Security-Policy'] = $this->parseDirectives($response->headers->get('X-Content-Security-Policy')); |
| 261 | + } |
| 262 | + |
| 263 | + return $headers; |
| 264 | + } |
| 265 | +} |
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