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 $flags Array Flags for this report
  67          * @param $logLine String text of log entry
  68          * @param $context Array 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 $report Array 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                         ( isset( $report['blocked-uri'] ) &&
 101                         isset( $falsePositives[$report['blocked-uri']] ) )
 102                         || ( isset( $report['source-file'] ) &&
 103                         isset( $falsePositives[$report['source-file']] ) )
 104                 ) {
 105                         // Report caused by Ad-Ware
 106                         $flags[] = 'false-positive';
 107                 }
 108                 return $flags;
 109         }
 110
 111         /**
 112          * Output an api error if post body is obviously not OK.
 113          */
 114         private function verifyPostBodyOk() {
 115                 $req = $this->getRequest();
 116                 $contentType = $req->getHeader( 'content-type' );
 117                 if ( $contentType !== 'application/json'
 118                         && $contentType !=='application/csp-report'
 119                 ) {
 120                         $this->error( 'wrongformat', __METHOD__ );
 121                 }
 122                 if ( $req->getHeader( 'content-length' ) > self::MAX_POST_SIZE ) {
 123                         $this->error( 'toobig', __METHOD__ );
 124                 }
 125         }
 126
 127         /**
 128          * Get the report from post body and turn into associative array.
 129          *
 130          * @return Array
 131          */
 132         private function getReport() {
 133                 $postBody = $this->getRequest()->getRawInput();
 134                 if ( strlen( $postBody ) > self::MAX_POST_SIZE ) {
 135                         // paranoia, already checked content-length earlier.
 136                         $this->error( 'toobig', __METHOD__ );
 137                 }
 138                 $status = FormatJson::parse( $postBody, FormatJson::FORCE_ASSOC );
 139                 if ( !$status->isGood() ) {
 140                         $msg = $status->getErrors()[0]['message'];
 141                         if ( $msg instanceof Message ) {
 142                                 $msg = $msg->getKey();
 143                         }
 144                         $this->error( $msg, __METHOD__ );
 145                 }
 146
 147                 $report = $status->getValue();
 148
 149                 if ( !isset( $report['csp-report'] ) ) {
 150                         $this->error( 'missingkey', __METHOD__ );
 151                 }
 152                 return $report['csp-report'];
 153         }
 154
 155         /**
 156          * Get text of log line.
 157          *
 158          * @param $flags Array of additional markers for this report
 159          * @param $report Array the csp report
 160          * @return String Text to put in log
 161          */
 162         private function generateLogLine( $flags, $report ) {
 163                 $flagText = '';
 164                 if ( $flags ) {
 165                         $flagText = '[' . implode( $flags, ', ' ) . ']';
 166                 }
 167
 168                 $blockedFile = isset( $report['blocked-uri'] ) ? $report['blocked-uri'] : 'n/a';
 169                 $page = isset( $report['document-uri'] ) ? $report['document-uri'] : 'n/a';
 170                 $line = isset( $report['line-number'] ) ? ':' . $report['line-number'] : '';
 171                 $warningText = $flagText .
 172                         ' Received CSP report: <' . $blockedFile .
 173                         '> blocked from being loaded on <' . $page . '>' . $line;
 174                 return $warningText;
 175         }
 176
 177         /**
 178          * Stop processing the request, and output/log an error
 179          *
 180          * @param $code String error code
 181          * @param $method String method that made error
 182          * @throws ApiUsageException Always
 183          */
 184         private function error( $code, $method ) {
 185                 $this->log->info( 'Error reading CSP report: ' . $code, [
 186                         'method' => $method,
 187                         'user-agent' => $this->getRequest()->getHeader( 'user-agent' )
 188                 ] );
 189                 // Return 400 on error for user agents to display, e.g. to the console.
 190                 $this->dieWithError(
 191                         [ 'apierror-csp-report', wfEscapeWikiText( $code ) ], 'cspreport-' . $code, [], 400
 192                 );
 193         }
 194
 195         public function getAllowedParams() {
 196                 return [
 197                         'reportonly' => [
 198                                 ApiBase::PARAM_TYPE => 'boolean',
 199                                 ApiBase::PARAM_DFLT => false
 200                         ],
 201                         'source' => [
 202                                 ApiBase::PARAM_TYPE => 'string',
 203                                 ApiBase::PARAM_DFLT => 'internal',
 204                                 ApiBase::PARAM_REQUIRED => false
 205                         ]
 206                 ];
 207         }
 208
 209         public function mustBePosted() {
 210                 return true;
 211         }
 212
 213         public function isWriteMode() {
 214                 return false;
 215         }
 216
 217         /**
 218          * Mark as internal. This isn't meant to be used by normal api users
 219          */
 220         public function isInternal() {
 221                 return true;
 222         }
 223
 224         /**
 225          * Even if you don't have read rights, we still want your report.
 226          */
 227         public function isReadMode() {
 228                 return false;
 229         }
 230
 231         /**
 232          * Doesn't touch db, so max lag should be rather irrelavent.
 233          *
 234          * Also, this makes sure that reports aren't lost during lag events.
 235          */
 236         public function shouldCheckMaxLag() {
 237                 return false;
 238         }
 239 }