includes/api/ApiCSPReport.php

   1 <?php
   2 /**
   3  * Copyright © 2015 Brian Wolff
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  */
  22
  23 use MediaWiki\Logger\LoggerFactory;
  24
  25 /**
  26  * Api module to receive and log CSP violation reports
  27  *
  28  * @ingroup API
  29  */
  30 class ApiCSPReport extends ApiBase {
  31
  32         private $log;
  33
  34         /**
  35          * These reports should be small. Ignore super big reports out of paranoia
  36          */
  37         const MAX_POST_SIZE = 8192;
  38
  39         /**
  40          * Logs a content-security-policy violation report from web browser.
  41          */
  42         public function execute() {
  43                 $reportOnly = $this->getParameter( 'reportonly' );
  44                 $logname = $reportOnly ? 'csp-report-only' : 'csp';
  45                 $this->log = LoggerFactory::getInstance( $logname );
  46                 $userAgent = $this->getRequest()->getHeader( 'user-agent' );
  47
  48                 $this->verifyPostBodyOk();
  49                 $report = $this->getReport();
  50                 $flags = $this->getFlags( $report );
  51
  52                 $warningText = $this->generateLogLine( $flags, $report );
  53                 $this->logReport( $flags, $warningText, [
  54                         // XXX Is it ok to put untrusted data into log??
  55                         'csp-report' => $report,
  56                         'method' => __METHOD__,
  57                         'user' => $this->getUser()->getName(),
  58                         'user-agent' => $userAgent,
  59                         'source' => $this->getParameter( 'source' ),
  60                 ] );
  61                 $this->getResult()->addValue( null, $this->getModuleName(), 'success' );
  62         }
  63
  64         /**
  65          * Log CSP report, with a different severity depending on $flags
  66          * @param array $flags Flags for this report
  67          * @param string $logLine text of log entry
  68          * @param array $context logging context
  69          */
  70         private function logReport( $flags, $logLine, $context ) {
  71                 if ( in_array( 'false-positive', $flags ) ) {
  72                         // These reports probably don't matter much
  73                         $this->log->debug( $logLine, $context );
  74                 } else {
  75                         // Normal report.
  76                         $this->log->warning( $logLine, $context );
  77                 }
  78         }
  79
  80         /**
  81          * Get extra notes about the report.
  82          *
  83          * @param array $report The CSP report
  84          * @return array
  85          */
  86         private function getFlags( $report ) {
  87                 $reportOnly = $this->getParameter( 'reportonly' );
  88                 $source = $this->getParameter( 'source' );
  89                 $falsePositives = $this->getConfig()->get( 'CSPFalsePositiveUrls' );
  90
  91                 $flags = [];
  92                 if ( $source !== 'internal' ) {
  93                         $flags[] = 'source=' . $source;
  94                 }
  95                 if ( $reportOnly ) {
  96                         $flags[] = 'report-only';
  97                 }
  98
  99                 if (
 100                         (
 101                                 ContentSecurityPolicy::falsePositiveBrowser( $userAgent ) &&
 102                                 $report['blocked-uri'] === "self"
 103                         ) ||
 104                         (
 105                                 isset( $report['blocked-uri'] ) &&
 106                                 isset( $falsePositives[$report['blocked-uri']] )
 107                         ) ||
 108                         (
 109                                 isset( $report['source-file'] ) &&
 110                                 isset( $falsePositives[$report['source-file']] )
 111                         )
 112                 ) {
 113                         // False positive due to:
 114                         // https://bugzilla.mozilla.org/show_bug.cgi?id=1026520
 115
 116                         $flags[] = 'false-positive';
 117                 }
 118                 return $flags;
 119         }
 120
 121         /**
 122          * Output an api error if post body is obviously not OK.
 123          */
 124         private function verifyPostBodyOk() {
 125                 $req = $this->getRequest();
 126                 $contentType = $req->getHeader( 'content-type' );
 127                 if ( $contentType !== 'application/json'
 128                         && $contentType !== 'application/csp-report'
 129                 ) {
 130                         $this->error( 'wrongformat', __METHOD__ );
 131                 }
 132                 if ( $req->getHeader( 'content-length' ) > self::MAX_POST_SIZE ) {
 133                         $this->error( 'toobig', __METHOD__ );
 134                 }
 135         }
 136
 137         /**
 138          * Get the report from post body and turn into associative array.
 139          *
 140          * @return Array
 141          */
 142         private function getReport() {
 143                 $postBody = $this->getRequest()->getRawInput();
 144                 if ( strlen( $postBody ) > self::MAX_POST_SIZE ) {
 145                         // paranoia, already checked content-length earlier.
 146                         $this->error( 'toobig', __METHOD__ );
 147                 }
 148                 $status = FormatJson::parse( $postBody, FormatJson::FORCE_ASSOC );
 149                 if ( !$status->isGood() ) {
 150                         $msg = $status->getErrors()[0]['message'];
 151                         if ( $msg instanceof Message ) {
 152                                 $msg = $msg->getKey();
 153                         }
 154                         $this->error( $msg, __METHOD__ );
 155                 }
 156
 157                 $report = $status->getValue();
 158
 159                 if ( !isset( $report['csp-report'] ) ) {
 160                         $this->error( 'missingkey', __METHOD__ );
 161                 }
 162                 return $report['csp-report'];
 163         }
 164
 165         /**
 166          * Get text of log line.
 167          *
 168          * @param array $flags of additional markers for this report
 169          * @param array $report the csp report
 170          * @return string Text to put in log
 171          */
 172         private function generateLogLine( $flags, $report ) {
 173                 $flagText = '';
 174                 if ( $flags ) {
 175                         $flagText = '[' . implode( ', ', $flags ) . ']';
 176                 }
 177
 178                 $blockedFile = isset( $report['blocked-uri'] ) ? $report['blocked-uri'] : 'n/a';
 179                 $page = isset( $report['document-uri'] ) ? $report['document-uri'] : 'n/a';
 180                 $line = isset( $report['line-number'] ) ? ':' . $report['line-number'] : '';
 181                 $warningText = $flagText .
 182                         ' Received CSP report: <' . $blockedFile .
 183                         '> blocked from being loaded on <' . $page . '>' . $line;
 184                 return $warningText;
 185         }
 186
 187         /**
 188          * Stop processing the request, and output/log an error
 189          *
 190          * @param string $code error code
 191          * @param string $method method that made error
 192          * @throws ApiUsageException Always
 193          */
 194         private function error( $code, $method ) {
 195                 $this->log->info( 'Error reading CSP report: ' . $code, [
 196                         'method' => $method,
 197                         'user-agent' => $this->getRequest()->getHeader( 'user-agent' )
 198                 ] );
 199                 // Return 400 on error for user agents to display, e.g. to the console.
 200                 $this->dieWithError(
 201                         [ 'apierror-csp-report', wfEscapeWikiText( $code ) ], 'cspreport-' . $code, [], 400
 202                 );
 203         }
 204
 205         public function getAllowedParams() {
 206                 return [
 207                         'reportonly' => [
 208                                 ApiBase::PARAM_TYPE => 'boolean',
 209                                 ApiBase::PARAM_DFLT => false
 210                         ],
 211                         'source' => [
 212                                 ApiBase::PARAM_TYPE => 'string',
 213                                 ApiBase::PARAM_DFLT => 'internal',
 214                                 ApiBase::PARAM_REQUIRED => false
 215                         ]
 216                 ];
 217         }
 218
 219         public function mustBePosted() {
 220                 return true;
 221         }
 222
 223         public function isWriteMode() {
 224                 return false;
 225         }
 226
 227         /**
 228          * Mark as internal. This isn't meant to be used by normal api users
 229          * @return bool
 230          */
 231         public function isInternal() {
 232                 return true;
 233         }
 234
 235         /**
 236          * Even if you don't have read rights, we still want your report.
 237          * @return bool
 238          */
 239         public function isReadMode() {
 240                 return false;
 241         }
 242
 243         /**
 244          * Doesn't touch db, so max lag should be rather irrelavent.
 245          *
 246          * Also, this makes sure that reports aren't lost during lag events.
 247          * @return bool
 248          */
 249         public function shouldCheckMaxLag() {
 250                 return false;
 251         }
 252 }